JP2020002353A - Polyimide film, polyimide material, layered body, member for display, touch panel member, liquid crystal display device, and organic electroluminescent display device - Google Patents

Abstract

To provide a film having excellent transparency and improved resistance to bending.SOLUTION: A polyimide film comprises a polyimide having the structure represented by the general formula (1) in the figure. As residual solvents within the film, the content of organic solvents having a boiling point lower than 100°C under 1 atmosphere is 2000 ppm or less, and the content of organic solvents having a boiling point higher than or equal to 100°C under 1 atmosphere is 100 ppm or less. The total light transmittance as measured according to JIS K7361-1 is 85% or more. In the formula (1), the symbols are as described in the specification.SELECTED DRAWING: None

Description

  The present invention relates to a polyimide film, a polyimide material, a laminate, a member for a display, a touch panel member, a liquid crystal display device, and an organic electroluminescence display device.

  Although thin sheet glass is excellent in hardness, heat resistance, etc., it is difficult to bend, easily breaks when dropped, has a problem in workability, and has a disadvantage that it is heavier than plastic products. Therefore, in recent years, resin products such as a resin base material and a resin film are being replaced with glass products from the viewpoint of workability and weight reduction, and research on resin products as glass substitute products has been conducted.

  For example, with the rapid progress of displays such as liquid crystals and organic EL, and electronics such as touch panels, devices have been required to be thinner and lighter and more flexible. In these devices, various electronic elements, such as thin transistors and transparent electrodes, are conventionally formed on a thin sheet glass. By changing this thin sheet glass to a resin film, the impact resistance of the panel itself is enhanced. In addition, flexibility, thinness and weight reduction can be achieved.

  Generally, polyimide is a highly heat-resistant resin obtained by subjecting a polyamic acid obtained by a condensation reaction between an aromatic tetracarboxylic anhydride and an aromatic diamine to a dehydration and ring-closing reaction. However, since polyimide generally shows yellow or brown coloring, it has been difficult to use it in fields requiring transparency, such as display applications and optical applications. Therefore, application of a polyimide with improved transparency to a display member has been studied. For example, Patent Document 1 discloses 1,2,4,5-cyclohexanetetracarboxylic acid and 1,2,4,5-cyclohexanetetracarboxylic acid as polyimide resins having high heat resistance, high transparency, and low water absorption. At least one acyl-containing compound selected from the group consisting of anhydrides and reactive derivatives thereof and at least one compound selected from compounds having at least one phenylene group and isopropylidene group represented by a specific formula A polyimide obtained by reacting with an imino-forming compound is disclosed, and is described as being suitable for a substrate material of a flat panel display, a mobile phone device, and the like.

  Further, Patent Document 2 includes a unit structure derived from an aromatic dianhydride and an aromatic diamine, an additive for improving tear strength, or a functional group selected from the group consisting of a hexafluoro group, a sulfone group, and an oxy group. A transparent polyimide film further including a unit structure derived from a monomer having the same is disclosed.

  In addition, Patent Document 3 discloses a polyimide film used for a substrate of a flexible device, which is a colorless and transparent polyimide film having a low residual stress generated between the film and an inorganic film and having excellent mechanical and thermal properties. For this purpose, a polyimide film in which a polyimide precursor using a specific fluorine-based aromatic diamine and a silicone compound having a siloxane skeleton having 3 to 200 silicon atoms as a monomer component is imidized is disclosed. . In Patent Document 3, when a polyimide film with an inorganic film (SiN film) was formed using the polyimide precursor, no crack or peeling was observed after a bending test in which bending was repeated 10 times (O), or cracks were observed. It is described as observed (△).

  Further, Patent Document 4 describes that as a polyimide having a low refractive index and high folding resistance, a silicone diamine having 2 to 21 silicon atoms is contained in an amount of 10% by weight or more based on the weight of the diamine raw material.

  Further, the inventors have disclosed in Patent Document 5 a diamine residue having one or two silicon atoms in the main chain as a resin film in which a decrease in surface hardness is suppressed while improving bending resistance. Discloses a polyimide film having a specific total light transmittance, a specific yellowness, a specific glass transition temperature, and a specific tensile modulus, comprising a polyimide containing 10 mol% or more and 50 mol% or less of the total amount of .

JP 2006-199945 A JP 2014-501301 A International Publication No. 2014/098235 JP 2008-64905 A JP 2018-28073 A

In the first place, resin products as glass substitute products are required to have excellent transparency.
The mobile device whose screen can be folded is in a folded state when being carried, and is in an opened state when being used. Therefore, it is required that a flexible display mounted on a mobile device does not cause display defects even if it is repeatedly bent. , Dynamic bending resistance). Furthermore, since mobile devices that can fold the screen are often carried in a folded state, the flexible display mounted on the mobile device will not return to its original state when it is folded back even if it is folded for a long time. It is also required that the substrate and the surface material for a flexible display have resilience after being folded for a long time (hereinafter, sometimes referred to as static bending resistance).
However, the bending resistance of the transparent polyimide film of the prior art has been required to be further improved.

The present invention has been made in view of the above problems, and has as its main object to provide a polyimide film having excellent transparency and improved bending resistance.
Further, the present invention provides a polyimide material for producing the polyimide film, a laminate having the polyimide, a display member that is the polyimide film or the laminate, and a touch panel member including the polyimide film or the laminate. , A liquid crystal display device, and an organic electroluminescence display device.

The polyimide film of the present invention contains a polyimide having a structure represented by the following general formula (1),
As a residual solvent in the film, the content of the organic solvent having a boiling point under 1 atm of less than 100 ° C. is 2000 ppm or less, and the content of the organic solvent having a boiling point at 1 atm of 100 ° C. or more is 100 ppm or less. Yes,
The total light transmittance measured according to JIS K7361-1 is 85% or more.

(In the general formula (1), R ¹ represents a tetravalent group that is a tetracarboxylic acid residue having an aromatic ring or an aliphatic ring; R ² represents a divalent group that is a diamine residue; 2.5 to 50 mol% of the total amount of ² are diamine residues having a silicon atom in the main chain, and 50 to 97.5 mol% do not have a silicon atom and are aromatic. A diamine residue having a ring or an aliphatic ring, and n represents the number of repeating units.)

  The polyimide film of the present invention has a tensile modulus of 1.8 GPa or more at 25 ° C. measured on a test piece of 15 mm × 40 mm according to JIS K7127 at a tensile speed of 10 mm / min and a distance between chucks of 20 mm. It is preferable from the viewpoint of excellent surface hardness.

  The polyimide film of the present invention preferably has a value obtained by dividing the yellowness calculated according to JIS K7373-2006 by the film thickness (μm) of 0.10 or less from the viewpoint of excellent transparency.

The polyimide film of the present invention is a polyimide having a structure represented by the general formula (1), wherein R ¹ in the general formula (1) is a cyclohexanetetracarboxylic dianhydride residue, cyclopentanetetracarboxylic acid Dianhydride residue, dicyclohexane-3,4,3 ', 4'-tetracarboxylic dianhydride residue, cyclobutanetetracarboxylic dianhydride residue, pyromellitic dianhydride residue, 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride residue, 2,2', 3,3'-biphenyltetracarboxylic dianhydride residue, 4,4 '-(hexafluoroisopropylidene) diphthalic acid Anhydride residue, 3,4 ′-(hexafluoroisopropylidene) diphthalic anhydride residue, 3,3 ′-(hexafluoroisopropylidene) diphthalic anhydride residue, 4,4′-oxydiene Talic anhydride residue, and that it is at least one tetravalent group selected from the group consisting of 3,4′-oxydiphthalic anhydride residue, light transmittance, bending resistance and surface hardness It is preferable from the point of view.

In the polyimide film of the present invention, in the polyimide having a structure represented by the general formula (1), R ² in the general formula (1) does not have the silicon atom and has an aromatic ring or an aliphatic ring. A diamine residue having a ring is trans-cyclohexanediamine residue, trans-1,4-bismethylenecyclohexanediamine residue, 4,4′-diaminodiphenylsulfone residue, 3,4′-diaminodiphenylsulfone residue, 2,2-bis (4-aminophenyl) propane residue, 3,3′-bis (trifluoromethyl) -4,4 ′-[(1,1,1,3,3,3-hexafluoropropane- 2,2-diyl) bis (4,1-phenyleneoxy)] dianiline residue, 2,2-bis [3- (3-aminophenoxy) phenyl] -1,1,1,3,3 A hexafluoropropane residue, a 2,2-bis [4- (4-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane residue, and a compound represented by the following general formula (2) It is preferable that it is at least one kind of divalent group selected from the group consisting of the divalent groups represented in view of light transmittance, bending resistance and surface hardness.

(In the general formula (2), R ³ and R ⁴ each independently represent a hydrogen atom, an alkyl group, or a perfluoroalkyl group.)

In the polyimide film of the present invention, in the polyimide having a structure represented by the general formula (1), R ² has a diamine residue having no silicon atom and one or two silicon atoms in a main chain. Represents a divalent group of at least one kind selected from diamine residues, wherein 2.5 to 50 mol% of the total amount of R ² is a diamine residue having one or two silicon atoms in the main chain. It is preferable from the viewpoint of improving bending resistance and surface hardness that 50 mol% or more and 97.5 mol% or less are a diamine residue having no silicon atom and having an aromatic ring or an aliphatic ring. .

Further, the present invention is a polyimide material for producing a polyimide film of the present invention,
It has a structure represented by the general formula (1), and has a content of an organic solvent having a boiling point of less than 100 ° C. under 1 atm at 2000 ppm or less as a residual solvent, and a boiling point at 100 atm. Provided is a polyimide material having an organic solvent content of 100 ° C. or higher and 100 ppm or lower.

  The present invention also provides a laminate having the polyimide film of the present invention and a hard coat layer containing at least one polymer of a radically polymerizable compound and a cationically polymerizable compound.

  The present invention also provides a display member, which is the polyimide film of the present invention or the laminate of the present invention. The display member can be for a flexible display.

Further, the present invention, the polyimide film of the present invention or the laminate of the present invention,
A transparent electrode composed of a plurality of conductive portions, disposed on one surface side of the polyimide film or the laminate,
And a plurality of lead wires electrically connected to at least one of the ends of the conductive portion.

Further, the present invention, the polyimide film of the present invention or the laminate of the present invention,
A liquid crystal display device, comprising: a liquid crystal display portion having a liquid crystal layer between opposing substrates, the liquid crystal display portion being disposed on one surface side of the polyimide film or the laminate.

Further, the present invention, the polyimide film of the present invention or the laminate of the present invention,
An organic electroluminescence display device comprising: an organic electroluminescence display portion having an organic electroluminescence layer between opposing substrates, the organic electroluminescence display portion being disposed on one surface side of the polyimide film or the laminate.

According to the present invention, it is possible to provide a polyimide film having excellent transparency and improved bending resistance.
Further, the present invention provides a polyimide material for producing the polyimide film, a laminate having the polyimide, a display member that is the polyimide film or the laminate, and a touch panel member including the polyimide film or the laminate. , A liquid crystal display device, and an organic electroluminescence display device.

It is a figure for explaining the method of a static bending test. It is an outline top view of one side of an example of the touch panel member of the present invention. FIG. 3 is a schematic plan view of another surface of the touch panel member shown in FIG. 2. FIG. 4 is a sectional view taken along line A-A ′ of the touch panel member shown in FIGS. 2 and 3. It is a schematic plan view showing an example of a conductive member provided with a layered product of the present invention. It is a schematic plan view which shows another example of the conductive member provided with the laminated body of this invention. It is an outline sectional view showing another example of the touch panel member of the present invention. FIG. 1 is a schematic sectional view illustrating an example of a liquid crystal display device of the present invention. FIG. 4 is a schematic sectional view showing another example of the liquid crystal display device of the present invention. FIG. 1 is a schematic cross-sectional view illustrating an example of the organic electroluminescence display device of the present invention. FIG. 2 is a schematic sectional view showing another example of the organic electroluminescence display device of the present invention.

Hereinafter, the polyimide film according to the present invention, a polyimide material for producing the polyimide film, a laminate using the polyimide film, a display member, a touch panel member, a liquid crystal display device, and an organic electroluminescence display device will be described in detail.
Further, in this specification, to specify the shape and geometric conditions and the degree thereof, for example, such as "parallel", "orthogonal", "identical" and the like, and the value of the length and angle, etc., strict Without being constrained by the meaning, it should be interpreted to include a range in which a similar function can be expected.
Moreover, in this specification, (meth) acryl represents each of acryl and methacryl.
Further, in the present specification, “light” means actinic rays or radiation, for example, a bright line spectrum of a mercury lamp, far ultraviolet represented by excimer laser, extreme ultraviolet (EUV light), X-ray, electron beam and the like. Included.
Further, in the drawings attached to this specification, for convenience of illustration and ease of understanding, the scale and vertical / horizontal ratio may be appropriately changed from those of the actual product and exaggerated.
In this specification, "ppm" used as a unit of the content of the organic solvent in the polyimide film represents ppm by mass.

I. Polyimide film The polyimide film of the present invention contains a polyimide having a structure represented by the following general formula (1),
As a residual solvent in the film, the content of the organic solvent having a boiling point under 1 atm of less than 100 ° C. is 2000 ppm or less, and the content of the organic solvent having a boiling point at 1 atm of 100 ° C. or more is 100 ppm or less. Yes,
The total light transmittance measured according to JIS K7361-1 is 85% or more.

(In the general formula (1), R ¹ represents a tetravalent group that is a tetracarboxylic acid residue having an aromatic ring or an aliphatic ring; R ² represents a divalent group that is a diamine residue; 2.5 to 50 mol% of the total amount of ² are diamine residues having a silicon atom in the main chain, and 50 to 97.5 mol% do not have a silicon atom and are aromatic. A diamine residue having a ring or an aliphatic ring, and n represents the number of repeating units.)

  According to the present invention, the polyimide contained in the polyimide film has a tetracarboxylic acid residue having an aromatic ring or an aliphatic ring, and a diamine residue having a silicon atom in a main chain as a diamine residue. It has a specific structure containing from 5 mol% to 50 mol%, and containing from 50 mol% to 97.5 mol% of a diamine residue having an aromatic ring or an aliphatic ring without a silicon atom, As a residual solvent, the content of the organic solvent having a boiling point of less than 100 ° C. at 1 atm is 2,000 ppm or less, and the content of the organic solvent having a boiling point of 100 ° C. or more at 1 atm is 100 ppm or less. By using a polyimide film having a total light transmittance, a polyimide film having excellent transparency and improved bending resistance can be provided.

  As described in Patent Document 5, the present inventors have found that when a diamine residue having one or two silicon atoms in the main chain is contained at an appropriate ratio in the total amount of diamine residues, the bending resistance is improved. Is disclosed. Further, as described in Patent Document 4, it is described that a polyimide film containing silicone diamine having 2 to 21 silicon atoms in an amount of 10% by weight or more based on the weight of the diamine raw material has high folding resistance. However, it has been found that even when the structure of the polyimide constituting the polyimide film is the same, the bending resistance changes depending on the method of manufacturing the polyimide film.

The present inventors, in a polyimide film containing a diamine residue having a silicon atom in the main chain at an appropriate ratio of the total amount of the diamine residue, among the residual solvent in the film, the boiling point at 1 atm (hereinafter, referred to as The content of an organic solvent having a boiling point of less than 100 ° C. is 2,000 ppm or less, and the content of an organic solvent having a boiling point of 100 ° C. or more at 1 atm is 100 ppm or less. Thereby, it was found that the bending resistance of the polyimide film was improved.
Since the residual solvent is a solvent used for producing the polyimide film, it is often a good solvent for the polyimide film. When the organic solvent having a boiling point of 100 ° C. or more exceeds 100 ppm as a residual solvent amount in the film, a part of the polyimide constituting the film is dissolved in the residual solvent, and the film is easily damaged during dynamic bending. It is presumed that it may be easily broken.
On the other hand, the organic solvent having a boiling point of less than 100 ° C. is not yet clear, but is less likely to affect the dynamic bending resistance of the film than the organic solvent having a boiling point of 100 ° C. or more, and a larger residual amount is acceptable. Is done. An organic solvent having a boiling point of less than 100 ° C. is more likely to affect the static bending resistance of the film than an organic solvent having a boiling point of 100 ° C. or more. This is because, when a large amount of the organic solvent having a boiling point of less than 100 ° C. remains in the film, a part of the organic solvent having a boiling point of less than 100 ° C. volatilizes in a state where the film is bent for a long time. It is presumed that a part of the part shrinks, and it becomes difficult to restore when it is returned to the flat state.
In the present invention, regarding the content of the residual solvent in the polyimide film, the organic solvent having a boiling point of less than 100 ° C. and the organic solvent having a boiling point of 100 ° C. or more are respectively set to a specific content ratio or less. It is presumed that a polyimide film that is hardly damaged at times and can be easily restored during static bending can be obtained.

In Examples and Comparative Examples described below, even when a polyimide film is manufactured using a polyimide precursor having the same molecular structure, the manufacturing method of the polyimide and the manufacturing method of the polyimide film are different and the state of the film is different. It shows that the amount of residual solvent changes and the bending resistance changes. This indicates that the bending resistance of the polyimide film does not depend only on the chemical structure of the polyimide, and that the amount of the residual solvent indicates the state of the polyimide film related to the bending resistance.
Further, by using the polyimide film having the specific total light transmittance, a polyimide film having excellent transparency and improved bending resistance can be provided.

Hereinafter, the polyimide film according to the present invention will be described in detail.
The polyimide film according to the present invention contains polyimide and has the specific characteristics described above. As long as the effects of the present invention are not impaired, the composition may further contain other components or may have other configurations.
1. Polyimide Polyimide is obtained by reacting a tetracarboxylic acid component with a diamine component. It is preferable to obtain a polyamic acid by polymerization of a tetracarboxylic acid component and a diamine component and imidize the polyamic acid. The imidation may be performed by thermal imidization or chemical imidization. Further, it can also be produced by a method using both thermal imidization and chemical imidization.
The polyimide used in the present invention contains a polyimide having a structure represented by the following general formula (1).

(In the general formula (1), R ¹ represents a tetravalent group that is a tetracarboxylic acid residue having an aromatic ring or an aliphatic ring; R ² represents a divalent group that is a diamine residue; 2.5 to 50 mol% of the total amount of ² are diamine residues having a silicon atom in the main chain, and 50 to 97.5 mol% do not have a silicon atom and are aromatic. A diamine residue having a ring or an aliphatic ring, and n represents the number of repeating units.)

Here, the tetracarboxylic acid residue means a residue obtained by removing four carboxyl groups from tetracarboxylic acid, and represents the same structure as the residue obtained by removing the acid dianhydride structure from tetracarboxylic dianhydride. .
The diamine residue refers to a residue obtained by removing two amino groups from a diamine.

The tetracarboxylic acid residue in R ¹ of the general formula (1) is a residue obtained by removing an acid dianhydride structure from a tetracarboxylic dianhydride having an aromatic ring, or a tetracarboxylic acid having an aliphatic ring. It can be a residue obtained by removing the acid dianhydride structure from dianhydride.
Examples of the tetracarboxylic dianhydride having an aromatic ring include pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, 2,2 ′, 3,3 ′ -Benzophenonetetracarboxylic dianhydride, 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, 2,2', 3,3'-biphenyltetracarboxylic dianhydride, 2,2-bis (3,4-dicarboxyphenyl) propane dianhydride, 2,2-bis (2,3-dicarboxyphenyl) propane dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, bis ( 3,4-dicarboxyphenyl) sulfone dianhydride, 1,1-bis (2,3-dicarboxyphenyl) ethane dianhydride, bis (2,3-dicarboxyphenyl) methane dianhydride, bis (3 , 4-Zika Boxyphenyl) methane dianhydride, 2,2-bis (3,4-dicarboxyphenyl) -1,1,1,3,3,3-hexafluoropropane dianhydride, 2,2-bis (2,3 -Dicarboxyphenyl) -1,1,1,3,3,3-hexafluoropropane dianhydride, 1,3-bis [(3,4-dicarboxy) benzoyl] benzene dianhydride, 1,4- Bis [(3,4-dicarboxy) benzoyl] benzene dianhydride, 2,2-bis {4- [4- (1,2-dicarboxy) phenoxy] phenyl} propane dianhydride, 2,2-bis {4- [3- (1,2-dicarboxy) phenoxy] phenyl} propane dianhydride, bis {4- [4- (1,2-dicarboxy) phenoxy] phenyl} ketone dianhydride, bis {4 -[3- (1,2-dicarboxy) Phenoxy] phenyl diketone dianhydride, 4,4'-bis [4- (1,2-dicarboxy) phenoxy] biphenyl dianhydride, 4,4'-bis [3- (1,2-dicarboxy) Phenoxy] biphenyl dianhydride, bis {4- [4- (1,2-dicarboxy) phenoxy] phenyl} ketone dianhydride, bis {4- [3- (1,2-dicarboxy) phenoxy] phenyl} Ketone dianhydride, bis {4- [4- (1,2-dicarboxy) phenoxy] phenyl} sulfone dianhydride, bis {4- [3- (1,2-dicarboxy) phenoxy] phenyl} sulfone Anhydride, bis {4- [4- (1,2-dicarboxy) phenoxy] phenyl} sulfide dianhydride, bis {4- [3- (1,2-dicarboxy) phenoxy] phenyl} sulfide dianhydride 4,4 ′-(hexafluoroisopropylidene) diphthalic anhydride, 3,4 ′-(hexafluoroisopropylidene) diphthalic anhydride, 3,3 ′-(hexafluoroisopropylidene) diphthalic anhydride, 4, 4'-oxydiphthalic anhydride, 3,4'-oxydiphthalic anhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 1,2,3,4-benzenetetracarboxylic dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, , 3,6,7-anthracenetetracarboxylic dianhydride, 1,2,7,8-phenanthrenetetracarboxylic dianhydride and the like.
Examples of the tetracarboxylic dianhydride having an aliphatic ring include cyclohexanetetracarboxylic dianhydride, cyclopentanetetracarboxylic dianhydride, dicyclohexane-3,4,3 ′, 4′-tetracarboxylic dianhydride. Anhydride, cyclobutanetetracarboxylic dianhydride and the like can be mentioned.
These can be used alone or in combination of two or more.

The diamine residue having a silicon atom in the main chain in R ² of the general formula (1) may be a residue obtained by removing two amino groups from a diamine having a silicon atom in the main chain. The polyimide film used in the present invention, as described above, by introducing a specific amount of a flexible molecular skeleton having a silicon atom in the main chain between molecular skeletons containing an aromatic ring or an aliphatic ring as a main component. In addition, the bending resistance can be improved. Further, when a functional layer such as a hard coat layer to be described later is laminated, the adhesiveness between the functional layer such as a hard coat layer and the like can be improved.

The diamine residue having a silicon atom in the main chain can be a residue obtained by removing two amino groups from a diamine having a silicon atom in the main chain.
Examples of the diamine residue having a silicon atom in the main chain include a diamine represented by the following general formula (A).

(In the general formula (A), L is each independently a direct bond or —O— bond, R ¹⁰ is each independently a substituent, and may contain an oxygen atom or a nitrogen atom. Represents a monovalent hydrocarbon group having 1 to 20 carbon atoms, each of which may be independently represented by R ¹¹ is a carbon atom which may independently have a substituent and may contain an oxygen atom or a nitrogen atom; Represents a divalent hydrocarbon group having a number of 1 to 20. k is a number from 0 to 200. A plurality of L, R ¹⁰ and R ¹¹ may be the same or different.

Examples of the monovalent hydrocarbon group represented by R ¹⁰ include an alkyl group having 1 to 20 carbon atoms, an aryl group, and a combination thereof. The alkyl group may be linear, branched, or cyclic, or may be a combination of linear or branched and cyclic.
The alkyl group having 1 to 20 carbon atoms is preferably an alkyl group having 1 to 10 carbon atoms, and specifically, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, Examples include a t-butyl group, a pentyl group, and a hexyl group. The cyclic alkyl group is preferably a cycloalkyl group having 3 to 10 carbon atoms, and specific examples thereof include a cyclopentyl group and a cyclohexyl group. The aryl group is preferably an aryl group having 6 to 12 carbon atoms, and specific examples include a phenyl group, a tolyl group, and a naphthyl group. Further, the monovalent hydrocarbon group represented by R ¹⁰ may be an aralkyl group, and examples thereof include a benzyl group, a phenylethyl group, and a phenylpropyl group.
Examples of the hydrocarbon group which may contain an oxygen atom or a nitrogen atom include, for example, an ether bond, a carbonyl bond, an ester bond, an amide bond, and an imino bond between a divalent hydrocarbon group described below and the monovalent hydrocarbon group. And a group bonded by at least one of the bonds (—NH—).
The substituent that the monovalent hydrocarbon group represented by R ¹⁰ may have is not particularly limited as long as the effects of the present invention are not impaired, and examples thereof include a halogen atom such as a fluorine atom and a chlorine atom. And a hydroxyl group.

As the monovalent hydrocarbon group represented by R ¹⁰ , an alkyl group having 1 to 3 carbon atoms or an aryl group having 6 to 10 carbon atoms is preferable from the viewpoint of improvement in bending resistance and compatibility of surface hardness. Preferably, it is an alkyl group having 1 to 3 carbon atoms. The alkyl group having 1 to 3 carbon atoms is more preferably a methyl group, and the aryl group having 6 to 10 carbon atoms is more preferably a phenyl group.

Examples of the divalent hydrocarbon group represented by R ¹¹ include an alkylene group having 1 to 20 carbon atoms, an arylene group, and a combination thereof. The alkylene group may be linear, branched, or cyclic, or may be a combination of linear, branched, and cyclic.
The alkylene group having 1 or more and 20 or less carbon atoms is preferably an alkylene group having 1 or more and 10 or less carbon atoms. And the like, and a combination of a cyclic or branched alkylene group and a cyclic alkylene group.
The arylene group is preferably an arylene group having 6 to 12 carbon atoms, and examples of the arylene group include a phenylene group, a biphenylene group, and a naphthylene group. You may have.
As the divalent hydrocarbon group which may contain an oxygen atom or a nitrogen atom, the divalent hydrocarbon group may be an ether bond, a carbonyl bond, an ester bond, an amide bond, or an imino bond (-NH-). A group bonded by at least one is exemplified.
The substituent that the divalent hydrocarbon group represented by R ¹¹ may have is the same as the substituent that the monovalent hydrocarbon group represented by R ¹⁰ may have. Good.

As the divalent hydrocarbon group represented by R ¹¹ , an alkylene group having 1 to 6 carbon atoms or an arylene group having 6 to 10 carbon atoms is preferable from the viewpoint of improvement in bending resistance and compatibility of surface hardness. The alkylene group is more preferably an alkylene group having 2 to 4 carbon atoms, and the alkylene group is preferably linear or branched.

  k is a number from 0 to 200. The average of k is preferably 0 or more and 6 or less, and more preferably 0 or more and 4 or less from the viewpoint of improvement in bending resistance and surface hardness compatibility. Among them, k is preferably 0 or 1.

As the diamine residue having a silicon atom in the main chain in R ² , among others, it has one or two silicon atoms in the main chain from the viewpoint of excellent bending resistance and excellent compatibility with surface hardness. Preferably, it is a diamine residue.

  Examples of the diamine having one silicon atom in the main chain include, among the diamines represented by the general formula (A), a diamine represented by the following general formula (A-1) where k = 0. . Examples of the diamine having two silicon atoms in the main chain include, among the diamines represented by the general formula (A), a diamine represented by the following general formula (A-2) where k = 1. No.

(In the general formula (A-1) and the general formula (A-2), L is each independently a direct bond or -O-bond, and R ¹⁰ is each independently a substituent. And represents a monovalent hydrocarbon group having 1 to 20 carbon atoms which may contain an oxygen atom or a nitrogen atom, wherein R ¹¹ each independently may have a substituent, and Or a divalent hydrocarbon group having 1 to 20 carbon atoms which may contain a nitrogen atom. A plurality of L, R ¹⁰ and R ¹¹ may be the same or different.)

From the viewpoint of imparting bending resistance while suppressing the mobility of the molecule and the compatibility of surface hardness, the molecular weight of the diamine residue having a silicon atom in the main chain is preferably 3,000 or less, and is 2,000 or less. Is preferably 1,000 or less, more preferably 800 or less, even more preferably 500 or less, and particularly preferably 300 or less.
Furthermore, the molecular weight of the diamine residue having one or two silicon atoms in the main chain is preferably 1,000 or less, more preferably 800 or less, even more preferably 500 or less, and 300 or less. Is particularly preferred.
The molecular weight of the diamine residue is calculated by subtracting the molecular weight (32) of _two amino groups (-NH2) from the molecular weight of the diamine.
Diamine residues having a silicon atom in the main chain can be used alone or in combination of two or more.

In the polyimide having the structure represented by the general formula (1), the diamine residue having a silicon atom in the main chain of R ² in the general formula (1) is a diamine residue having two silicon atoms. Is preferable in terms of light transmittance, bending resistance and surface hardness. Further, 1,3-bis (3-aminopropyl) tetramethyldisiloxane residue and 1,3-bis (4- Aminobutyl) tetramethyldisiloxane, 1,3-bis (5-aminopentyl) tetramethyldisiloxane, and the like are preferable from the viewpoint of easy availability and compatibility between light transmittance and surface hardness.

The diamine residue having an aromatic ring without a silicon atom in R ² of the general formula (1) is a residue obtained by removing two amino groups from a diamine having an aromatic ring without a silicon atom. can do.
Examples of the diamine having no silicon atom and having an aromatic ring include, for example, p-phenylenediamine, m-phenylenediamine, o-phenylenediamine, 3,3′-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether, 4, 4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl sulfide, 3,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfone 4,4'-diaminodiphenylsulfone, 3,3'-diaminobenzophenone, 4,4'-diaminobenzophenone, 3,4'-diaminobenzophenone, 4,4'-diaminobenzanilide, 3,3'-diaminodiphenylmethane , 4,4'-diaminodiphenylmethane 3,4'-diaminodiphenylmethane, 2,2-di (3-aminophenyl) propane, 2,2-di (4-aminophenyl) propane, 2- (3-aminophenyl) -2- (4-aminophenyl ) Propane, 2,2-di (3-aminophenyl) -1,1,1,3,3,3-hexafluoropropane, 2,2-di (4-aminophenyl) -1,1,1,3 , 3,3-hexafluoropropane, 2- (3-aminophenyl) -2- (4-aminophenyl) -1,1,1,3,3,3-hexafluoropropane, 1,1-di (3 -Aminophenyl) -1-phenylethane, 1,1-di (4-aminophenyl) -1-phenylethane, 1- (3-aminophenyl) -1- (4-aminophenyl) -1-phenylethane, 1,3-bis (3-aminopheno B) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,4-bis (3-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) benzene, 1,3-bis (3 -Aminobenzoyl) benzene, 1,3-bis (4-aminobenzoyl) benzene, 1,4-bis (3-aminobenzoyl) benzene, 1,4-bis (4-aminobenzoyl) benzene, 1,3-bis (3-amino-α, α-dimethylbenzyl) benzene, 1,3-bis (4-amino-α, α-dimethylbenzyl) benzene, 1,4-bis (3-amino-α, α-dimethylbenzyl) Benzene, 1,4-bis (4-amino-α, α-dimethylbenzyl) benzene, 1,3-bis (3-amino-α, α-ditrifluoromethylbenzyl) benzene, 1,3-bis ( 4-amino-α, α-ditrifluoromethylbenzyl) benzene, 1,4-bis (3-amino-α, α-ditrifluoromethylbenzyl) benzene, 1,4-bis (4-amino-α, α- Ditrifluoromethylbenzyl) benzene, 2,6-bis (3-aminophenoxy) benzonitrile, 2,6-bis (3-aminophenoxy) pyridine, N, N′-bis (4-aminophenyl) terephthalamide, 9 , 9-bis (4-aminophenyl) fluorene, 2,2′-dimethyl-4,4′-diaminobiphenyl, 2,2′-ditrifluoromethyl-4,4′-diaminobiphenyl (2,2-bis ( Trifluoromethyl) benzidine), 3,3'-dichloro-4,4'-diaminobiphenyl, 3,3'-dimethoxy-4,4'-diaminobiphenyl, 3,3'-dimethyl -4,4'-diaminobiphenyl, 4,4'-bis (3-aminophenoxy) biphenyl, 4,4'-bis (4-aminophenoxy) biphenyl, bis [4- (3-aminophenoxy) phenyl] Ketone, bis [4- (4-aminophenoxy) phenyl] ketone, bis [4- (3-aminophenoxy) phenyl] sulfide, bis [4- (4-aminophenoxy) phenyl] sulfide, bis [4- (3 -Aminophenoxy) phenyl] sulfone, bis [4- (4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] ether, bis [4- (4-aminophenoxy) phenyl] ether, 2,2-bis [4- (3-aminophenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) Enyl] propane, 2,2-bis [3- (3-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, 2,2-bis [4- (4-aminophenoxy) ) Phenyl] -1,1,1,3,3,3-hexafluoropropane, 1,3-bis [4- (3-aminophenoxy) benzoyl] benzene, 1,3-bis [4- (4-amino Phenoxy) benzoyl] benzene, 1,4-bis [4- (3-aminophenoxy) benzoyl] benzene, 1,4-bis [4- (4-aminophenoxy) benzoyl] benzene, 1,3-bis [4- (3-aminophenoxy) -α, α-dimethylbenzyl] benzene, 1,3-bis [4- (4-aminophenoxy) -α, α-dimethylbenzyl] benzene, 1,4-bis [4- (3 -Amino Phenoxy) -α, α-dimethylbenzyl] benzene, 1,4-bis [4- (4-aminophenoxy) -α, α-dimethylbenzyl] benzene, 4,4′-bis [4- (4-aminophenoxy) ) Benzoyl] diphenyl ether, 4,4′-bis [4- (4-amino-α, α-dimethylbenzyl) phenoxy] benzophenone, 4,4′-bis [4- (4-amino-α, α-dimethylbenzyl) ) Phenoxy] diphenylsulfone, 4,4′-bis [4- (4-aminophenoxy) phenoxy] diphenylsulfone, 3,3′-diamino-4,4′-diphenoxybenzophenone, 3,3′-diamino-4 4,4'-dibiphenoxybenzophenone, 3,3'-diamino-4-phenoxybenzophenone, 3,3'-diamino-4-biphenoxybenzophenone, 6 6'-bis (3-aminophenoxy) -3,3,3 ', 3'-tetramethyl-1,1'-spirobiindane, 6,6'-bis (4-aminophenoxy) -3,3,3' , 3′-tetramethyl-1,1′-spirobiindane and the like, and a part or all of hydrogen atoms on an aromatic ring of the diamine is a fluoro group, a methyl group, a methoxy group, a trifluoromethyl group, or a trifluoromethoxy group. Diamines substituted with a substituent selected from the groups can also be used.
These can be used alone or in combination of two or more.

The diamine residue having an aliphatic ring without a silicon atom in R ² of the general formula (1) may be a residue obtained by removing two amino groups from a diamine having an aliphatic ring.
Examples of the diamine having an aliphatic ring include 1,4-cyclohexanediamine, trans-1,4-bismethylenecyclohexanediamine, 2,6-bis (aminomethyl) bicyclo [2,2,1] heptane, 5-bis (aminomethyl) bicyclo [2,2,1] heptane and the like.
These can be used alone or in combination of two or more.

In the polyimide film used in the present invention, in R ² of the general formula (1), 2.5 mol% or more and 50 mol% or less of the total amount of R ² are diamine residues having a silicon atom in a main chain, When 50 mol% or more and 97.5 mol% or less are a diamine residue having no aromatic atom or an aromatic ring having no silicon atom, static bending resistance and dynamic bending resistance are improved.
R ^{2 in the} general formula (1) is preferably 3 mol% or more, more preferably 4 mol% or more of the total amount of R ² , from the viewpoint of bending resistance, the diamine residue having a silicon atom in the main chain. Preferably, it is more preferably 5 mol% or more. Further, from the viewpoint of reducing optical distortion, the diamine residue having a silicon atom in the main chain may be at least 10 mol% or at least 15 mol% of the total amount of R ² . On the other hand, in the case of R ^{2 in the} general formula (1), the diamine residue having a silicon atom in the main chain is 45 mol% or less of the total amount of R ² from the viewpoint of improving surface hardness and light transmittance. It is more preferably at most 40 mol%, and from the viewpoint of compatibility between excellent surface hardness and dynamic bending resistance, it is also preferably less than 10 mol%.
On the other hand, the diamine residue having an aromatic ring or an aliphatic ring having no silicon atom is preferably 55 mol% or more of the total amount of R ² from the viewpoint of improving surface hardness and light transmittance. And more preferably 60 mol% or more, and may be more than 90 mol% from the viewpoint of excellent surface hardness. In addition, the diamine residue having no aromatic atom or an aromatic ring having no silicon atom is preferably 97 mol% or less, more preferably 96 mol% or less of the total amount of R ² from the viewpoint of bending resistance. It is more preferable that the content is even more preferably 95 mol% or less.
Incidentally, 50 mol% 2.5 mol% or more of the total amount of ^{R 2} or less, a diamine residue having a silicon atom in the main chain, 97.5 mol% to 50 mol% or less, having no silicon atom If it is a diamine residue having an aromatic ring or an aliphatic ring, R ² in the general formula (1) may be a diamine residue having a silicon atom in the main chain or an aromatic group having no silicon atom. It does not prevent including other diamine residues different from the diamine residue having a ring or an aliphatic ring. The other diamine residue is preferably at most 10 mol%, more preferably at most 5 mol%, further preferably at most 3 mol%, particularly preferably at most 1 mol% of the total amount of R ^2. The following is preferred. Examples of the other diamine residue include a diamine residue having no silicon atom and not having an aromatic ring and an aliphatic ring.

Among them, R ² in the general formula (1) is a diamine residue having no silicon atom, and has one or two silicon atoms in the main chain, from the viewpoint of improving both bending resistance and surface hardness. Represents a divalent group of at least one kind selected from diamine residues, wherein 2.5 to 50 mol% of the total amount of R ² is a diamine residue having one or two silicon atoms in the main chain. It is preferable that 50 mol% or more and 97.5 mol% or less are diamine residues having no silicon atom and having an aromatic ring or an aliphatic ring.
R ^{2 in the} general formula (1) is preferably a diamine residue having one or two silicon atoms in the main chain at 3 mol% or more of the total amount of R ² from the viewpoint of improving the bending resistance. And more preferably 4 mol% or more, and further preferably 5 mol% or more. From the viewpoint of reducing optical distortion, the diamine residue having one or two silicon atoms in the main chain may be at least 10 mol% or at least 15 mol% of the total amount of R ^2. Is also good. On the other hand, R ^{2 in the} general formula (1) is a diamine residue having one or two silicon atoms in the main chain in an amount of 45 mol% of the total amount of R ² from the viewpoint of improving surface hardness and light transmittance. It is preferably at most 40 mol%, more preferably at most 40 mol%, and in view of compatibility between excellent surface hardness and dynamic bending resistance, it is also preferably at most 10 mol%.
Above all, 2.5 mol% or more and 50 mol% or less of the total amount of R ² are diamine residues having one or two silicon atoms in the main chain, and among the total amount of R ² (100 mol%), The remainder (100% -x%) of the mol% (x mol%) of the diamine residue having one or two silicon atoms in the main chain is 50 mol% or more and 97.5 mol% or less and has a silicon atom. Instead, it is preferably a diamine residue having an aromatic ring or an aliphatic ring.
In addition, from the viewpoint of compatibility between excellent surface hardness and dynamic bending resistance, the diamine residue having one or two silicon atoms in the main chain accounts for 2.5 mol% or more and less than 10 mol% of the total amount of R ^2. a group, of the total amount of ^{R 2} (100 mol%), in mole% of the diamine residues having one or two silicon atoms in the main chain remaining (100% -x%) of (x mol%) It is also preferable that a certain excess of 90 mol% to 97.5 mol% or less is a diamine residue having no aromatic atom or an aromatic ring or an aliphatic ring.

In addition, the polyimide used in the present invention preferably has a silicon atom content ratio (% by mass) of 0.7% by mass or more and 6.5% by mass or less from the viewpoint of bending resistance and surface hardness. It is more preferably from 0.7% by mass to 5.5% by mass, and still more preferably from 0.7% by mass to 4.2% by mass.
Here, the content ratio (% by mass) of silicon atoms in the polyimide refers to the content ratio (% by mass) of silicon atoms in the total of two or more types of polyimide when two or more types of polyimides are used. At the time of polyimide production, it can be determined from the molecular weight of the charge. The content (% by mass) of the silicon atom in the polyimide was determined by decomposing the polyimide in the same manner as described below, using a high-performance liquid chromatography, gas chromatograph mass spectrometer, NMR, elemental analysis, XPS / ESCA and TOF. -It can be determined using SIMS.
(Silicon atom content of polyimide (% by mass))
For example, 2,2'-bis (trifluoromethyl) benzidine (TFMB) is used as a diamine component per 1 mol of 4,4 '-(hexafluoroisopropylidene) diphthalic anhydride (6FDA) as an acid dianhydride component. When 0.9 mol and 0.1 mol of 1,3-bis (3-aminopropyl) tetramethyldisiloxane (AprTMOS) are used, it can be calculated as follows.
The molecular weight of one mole of the polyimide repeating unit is
From 6FDA: (C) 12.01 × 19 + (F) 19.00 × 6 + (O) 16.00 × 4 + (H) 1.01 × 6 = 412.25
From TFMB: {(C) 12.01 × 14 + (F) 19.00 × 6 + (N) 14.01 × 2 + (H) 1.01 × 6} × 0.9 = 284.60
From AprTMOS: {(C) 12.01 × 10 + (O) 16.00 × 1 + (N) 14.01 × 2 + (Si) 28.09 × 2 + (H) 1.01 × 24} × 0.1 = 24.45
Is calculated as 412.25 + 284.60 + 24.45 = 721.30.
The silicon atom content ratio (% by mass) in 1 mol of the polyimide repeating unit is
(28.09 × 2 × 0.1) /721.30×100=0.8 (% by mass).

As the polyimide having the structure represented by the general formula (1), from the viewpoint of improving light transmittance and improving surface hardness, among others, an aromatic ring is contained, and (i) a fluorine atom; A polyimide containing at least one selected from the group consisting of (ii) an aliphatic ring and (iii) a structure in which aromatic rings are connected to each other by a sulfonyl group or an alkylene group which may be substituted by fluorine. Is preferred. The polyimide having the structure represented by the general formula (1) has a rigid molecular skeleton by containing at least one selected from tetracarboxylic acid residues having an aromatic ring and diamine residues having an aromatic ring. Although the orientation property is enhanced and the surface hardness is improved, the rigid aromatic ring skeleton tends to increase the absorption wavelength to a longer wavelength, and the transmittance in the visible light region tends to decrease.
When the polyimide contains (i) a fluorine atom, light transmission is improved because charge transfer of the electronic state in the polyimide skeleton can be made difficult.
When the polyimide contains (ii) an aliphatic ring, light transmission is improved because the transfer of charges in the skeleton can be inhibited by cutting off the conjugation of π electrons in the polyimide skeleton.
When the polyimide contains (iii) a structure in which aromatic rings are connected to each other by a sulfonyl group or an alkylene group which may be substituted with fluorine, the transfer of electric charge in the skeleton is prevented by cutting off the conjugation of π electrons in the polyimide skeleton. The light transmittance is improved because it can be inhibited.

As the polyimide having the structure represented by the general formula (1), a polyimide containing a fluorine atom is particularly preferably used from the viewpoint of improving light transmittance and improving surface hardness.
The content ratio of fluorine atoms is preferably such that the ratio (F / C) of the number of fluorine atoms (F) to the number of carbon atoms (C) of the polyimide surface measured by X-ray photoelectron spectroscopy is 0.01 or more, Further, it is preferably 0.05 or more. On the other hand, if the content ratio of fluorine atoms is too high, the inherent heat resistance of the polyimide may be reduced. Therefore, the ratio (F / C) of the number of fluorine atoms (F) to the number of carbon atoms (C) is 1 or less. And more preferably 0.8 or less.
Here, the above ratio determined by X-ray photoelectron spectroscopy (XPS) can be determined from the value of atomic% of each atom measured using an X-ray photoelectron spectroscopy apparatus (for example, Thermo Probe, Theta Probe). .

In addition, polyimide having a structure represented by the general formula (1) has a higher aromaticity when the total of R ¹ and R ² in the general formula (1) is 100 mol% from the viewpoint of improving the surface hardness. The total of the tetracarboxylic acid residue having an aromatic ring and the diamine residue having an aromatic ring is preferably 50 mol% or more, more preferably 60 mol% or more, and preferably 75 mol% or more. Even more preferred.

Further, the polyimide having the structure represented by the general formula (1) has a tetracarboxylic acid residue of R ^{1 and} an aromatic compound having no silicon atom of R ² because the surface hardness and light transmittance are improved. At least one of the diamine residues having an aromatic ring or an aliphatic ring preferably contains an aromatic ring and a fluorine atom, and further has no tetracarboxylic acid residue of R ¹ and no silicon atom of R ² It is preferable that both of the diamine residue having an aromatic ring or an aliphatic ring include an aromatic ring and a fluorine atom.
The polyimide having the structure represented by the general formula (1) has a surface hardness and a light transmittance that are improved, and when the total of R ¹ and R ² in the general formula (1) is 100 mol%. The total of tetracarboxylic acid residues having an aromatic ring and a fluorine atom and diamine residues having an aromatic ring and a fluorine atom is preferably at least 50 mol%, more preferably at least 60 mol%, Even more preferably, it is at least 75 mol%.

The polyimide having a structure represented by the general formula (1) is a polyimide in which 50% or more of the hydrogen atoms bonded to carbon atoms contained in the polyimide are hydrogen atoms directly bonded to an aromatic ring. Is preferably used in terms of improving light transmittance and improving surface hardness. The proportion of the hydrogen atoms (number) directly bonded to the aromatic ring in the total hydrogen atoms (number) bonded to the carbon atoms contained in the polyimide is preferably 60% or more, more preferably 70% or more. It is preferable that
When 50% or more of the hydrogen atoms bonded to the carbon atoms contained in the polyimide is a polyimide which is a hydrogen atom directly bonded to an aromatic ring, the polyimide is stretched at, for example, 200 ° C. or more even after a heating step in the air. Is preferable because the change in optical characteristics, particularly the total light transmittance and the yellowness YI value, is small. When at least 50% of the hydrogen atoms bonded to carbon atoms contained in the polyimide are hydrogen atoms directly bonded to the aromatic ring, the polyimide has a low chemical reactivity due to low reactivity with oxygen. It is presumed to be difficult. Polyimide films use their high heat resistance and are often used for devices that require processing steps involving heating, but more than 50% of the hydrogen atoms bonded to carbon atoms contained in the polyimide are converted to aromatic rings. In the case of polyimide, which is a hydrogen atom directly bonded, there is no need to perform these post-processes in an inert atmosphere to maintain transparency, so that there is an advantage in that equipment costs and costs for atmosphere control can be suppressed. There is.
Here, the ratio of the hydrogen atoms (number) directly bonded to the aromatic ring in the total hydrogen atoms (number) bonded to the carbon atoms contained in the polyimide is determined by decomposing the polyimide by high-performance liquid chromatography or gas chromatography. It can be determined using an analyzer and NMR. For example, the sample is decomposed with an aqueous alkali solution or supercritical methanol, and the decomposed product of the obtained polyimide is separated by high performance liquid chromatography, and the qualitative analysis of each separated peak is performed by gas chromatography mass spectrometry and NMR. The ratio of hydrogen atoms (number) directly bonded to the aromatic ring in all the hydrogen atoms (number) contained in the polyimide can be determined by quantification using high performance liquid chromatography.

Among the polyimides having the structure represented by the general formula (1), R ¹ in the general formula (1) is preferably cyclohexanetetracarboxylic acid from the viewpoints of light transmittance, bending resistance, and surface hardness. Dianhydride residue, cyclopentanetetracarboxylic dianhydride residue, dicyclohexane-3,4,3 ', 4'-tetracarboxylic dianhydride residue, cyclobutanetetracarboxylic dianhydride residue, pyro Melitic dianhydride residue, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride residue, 2,2 ′, 3,3′-biphenyltetracarboxylic dianhydride residue, 4, 4 ′-(hexafluoroisopropylidene) diphthalic anhydride residue, 3,4 ′-(hexafluoroisopropylidene) diphthalic anhydride residue, 3,3 ′-(hexafluoroisopropylidene) diphthalic anhydride residue Group It is preferably at least one tetravalent group selected from the group consisting of 1,4,4'-oxydiphthalic anhydride residue and 3,4'-oxydiphthalic anhydride residue.
In the R ^1, these preferred residues in total, preferably contains more than 50 mol%, preferably contains more than 70 mol%, it is preferable to include even more than 90 mol%.
In particular, R ¹ in the general formula (1) is a 4,4 ′-(hexafluoroisopropylidene) diphthalic anhydride residue and 3,4 ′-( (Hexafluoroisopropylidene) diphthalic anhydride residue, 3,3 ′-(hexafluoroisopropylidene) diphthalic anhydride residue, 4,4′-oxydiphthalic anhydride residue, and 3,4′-oxydiphthalic acid residue More preferably, it is at least one tetravalent group selected from the group consisting of acid anhydride residues.

As R ^{1 in the} general formula (1), pyromellitic dianhydride residue, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride residue, and 2,2 ′, 3 A group of tetracarboxylic acid residues (Group A) suitable for improving rigidity, such as at least one selected from the group consisting of 3'-biphenyltetracarboxylic dianhydride residues; Anhydride residue, cyclopentanetetracarboxylic dianhydride residue, dicyclohexane-3,4,3 ′, 4′-tetracarboxylic dianhydride residue, cyclobutanetetracarboxylic dianhydride residue, 4, 4 ′-(hexafluoroisopropylidene) diphthalic anhydride residue, 3,4 ′-(hexafluoroisopropylidene) diphthalic anhydride residue, 3,3 ′-(hexafluoroisopropylidene) diphthalic acid residue An acid anhydride residue, 4,4'-oxydiphthalic anhydride residue, and at least one selected from the group consisting of 3,4'-oxydiphthalic anhydride residue to improve light transmittance. It is also preferable to use a mixture with a tetracarboxylic acid residue group (group B) suitable for the above. In this case, the content ratio of the tetracarboxylic acid residue group (group A) suitable for improving the rigidity and the tetracarboxylic acid residue group (group B) suitable for improving the light transmittance is as follows. The amount of the tetracarboxylic acid residue group (Group A) suitable for improving the rigidity is 0.1 mol per 1 mol of the tetracarboxylic acid residue group (Group B) suitable for improving the light transmittance. It is preferably from 05 mol to 9 mol, more preferably from 0.1 mol to 5 mol, even more preferably from 0.3 mol to 4 mol.
Among them, the group B includes a 4,4 ′-(hexafluoroisopropylidene) diphthalic anhydride residue and a 3,4 ′-(hexafluoroisopropylidene) diphthalic anhydride residue containing a fluorine atom. It is preferable to use at least one kind from the viewpoint of improving surface hardness and light transmittance.

In the polyimide having the structure represented by the general formula (1), a diamine residue having an aromatic ring or an aliphatic ring without the silicon atom in R ² in the general formula (1) has trans -Cyclohexanediamine residue, trans-1,4-bismethylenecyclohexanediamine residue, 4,4′-diaminodiphenylsulfone residue, 3,4′-diaminodiphenylsulfone residue, 2,2-bis (4-amino Phenyl) propane residue, 3,3′-bis (trifluoromethyl) -4,4 ′-[(1,1,1,3,3,3-hexafluoropropane-2,2-diyl) bis (4 , 1-phenyleneoxy)] dianiline residue, 2,2-bis [3- (3-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane residue, 2,2- Screw[ -(4-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane residue and at least one selected from the group consisting of divalent groups represented by the following general formula (2) One kind of divalent group is preferable from the viewpoint of light transmittance and bending resistance and surface hardness. In particular, from the viewpoint of compatibility between light transmittance and surface hardness, 4,4′-diamino is further preferred. A group consisting of a diphenylsulfone residue, a 3,4′-diaminodiphenylsulfone residue, a 2,2-bis (4-aminophenyl) propane residue, and a divalent group represented by the following general formula (2) It is preferably at least one kind of divalent group selected from the following, and more preferably a divalent group represented by the following general formula (2). As the divalent group represented by the following general formula (2), R ³ and R ⁴ are more preferably perfluoroalkyl groups, and among them, a perfluoroalkyl group having 1 to 3 carbon atoms is preferable, More preferably, it is a trifluoromethyl group or a perfluoroethyl group. Further, as the alkyl group for R ³ and R ⁴ in the following general formula (2), an alkyl group having 1 to 3 carbon atoms is preferable, and a methyl group or an ethyl group is more preferable.

(In the general formula (2), R ³ and R ⁴ each independently represent a hydrogen atom, an alkyl group, or a perfluoroalkyl group.)

  The content ratio of each repeating unit and the content ratio (mol%) of each tetracarboxylic acid residue and each diamine residue in the polyimide can be determined from the molecular weight charged during the production of the polyimide. In addition, the content ratio (mol%) of each tetracarboxylic acid residue and each diamine residue in the polyimide was determined by using a high-performance liquid chromatography, gas chromatograph mass spectrometer, NMR , Elemental analysis, XPS / ESCA and TOF-SIMS.

In the structure represented by the general formula (1), n represents the number of repeating units, and is 1 or more.
The number n of repeating units in the polyimide is preferably appropriately selected according to the structure so as to exhibit a preferable glass transition temperature described later, but is not particularly limited.
The average number of repeating units is usually from 10 to 2,000, and preferably from 15 to 1,000.
Note that R ¹ in each repeating unit may be the same or different, and R ² in each repeating unit may be the same or different.

Further, the polyimide having the structure represented by the general formula (1) preferably has a number average molecular weight of 10,000 or more, more preferably 20,000 or more, from the viewpoint of strength and bending resistance when formed into a film. Preferably, it is still more preferably 30,000 or more, and particularly preferably 50,000 or more. The upper limit is not particularly limited, but is preferably 1000000 or less, more preferably 500,000 or less, from the viewpoint of easy synthesis and availability.
In addition, the number average molecular weight of the polyimide can be measured in the same manner as the number average molecular weight of the polyimide precursor described later.

Further, the polyimide having the structure represented by the general formula (1) preferably has a weight average molecular weight of 20,000 or more, and more preferably 30,000 or more, from the viewpoint of strength and bending resistance when formed into a film. More preferably, it is still more preferably 40,000 or more, and particularly preferably 80,000 or more. The upper limit is not particularly limited, but is preferably 1000000 or less, more preferably 500,000 or less, from the viewpoint of easy synthesis and availability.
The weight average molecular weight of the polyimide can be measured by gel permeation chromatography (GPC). Specifically, a polyimide was used as an N-methylpyrrolidone (NMP) solution having a concentration of 0.1% by weight, and a developing solvent used was a 30 mmol% LiBr-NMP solution having a water content of 500 ppm or less. 8120, column used: GPC LF-804 manufactured by SHODEX), and measurement is performed under the conditions of a sample injection amount of 50 μL, a solvent flow rate of 0.4 mL / min, and 37 ° C. The weight average molecular weight is determined based on a polystyrene standard sample having the same concentration as the sample.

The polyimide used in the present invention may partially have a structure different from the structure represented by the general formula (1) as long as the effects of the present invention are not impaired. In the polyimide used in the present invention, the structure represented by the general formula (1) is preferably 95% or more, more preferably 98% or more, and more preferably 100% or more of the total number of repeating units of the polyimide. It is even more preferred.
Examples of the structure different from the structure represented by the general formula (1) include a case where a tetracarboxylic acid residue having no aromatic ring or aliphatic ring is included, and a polyamide structure.
Examples of the polyamide structure that may be included include a polyamideimide structure containing a tricarboxylic acid residue such as trimellitic anhydride and a polyamide structure containing a dicarboxylic acid residue such as terephthalic acid.

The polyimide used in the present invention, in the tan δ curve which is a value obtained by dividing the loss elastic modulus by the storage elastic modulus, that having a peak apex only in a temperature region of 150 ° C. or more, improves flex resistance. Is preferred. The polyimide used in the present invention preferably has a peak apex only in a temperature region of 200 ° C. or higher in the tan δ curve from the viewpoint of improving bending resistance and surface hardness, and has a temperature of 220 ° C. or higher. It is even more preferred that it is provided only in the region. On the other hand, from the viewpoint that the baking temperature can be reduced, the peak of the peak in the tan δ curve is preferably in a temperature range of 380 ° C. or less. Further, the polyimide used in the present invention preferably has one peak of a tan δ curve in a temperature range of 150 ° C. or more and 400 ° C. or less.
In addition, the polyimide used in the present invention preferably has no tan δ curve peak in a temperature region of −150 ° C. or more and 0 ° C. or less in a temperature region of −150 ° C. or more and less than 150 ° C., whereby the polyimide The surface hardness of the film at room temperature can be improved.
The tan δ curve of the polyimide used in the present invention can be measured in the same manner as the tan δ curve of a polyimide film described later.

2. Additives In addition to the polyimide, the polyimide film of the present invention may further contain additives as necessary. Examples of the additive include inorganic particles, a silica filler for facilitating winding, and a surfactant for improving film forming property and defoaming property.

3. Characteristics of Polyimide Film The polyimide film of the present invention has the specific residual solvent amount and the specific total light transmittance. It is preferable that the polyimide film of the present invention further has characteristics described later.

(1) Residual Solvent Amount The polyimide film of the present invention has, as a residual solvent in the film, a content of an organic solvent having a boiling point under 1 atm of less than 100 ° C. is 2000 ppm or less, and a boiling point under 1 atm. The content of the organic solvent at 100 ° C. or higher is 100 ppm or lower.
The content of the organic solvent having a boiling point of less than 100 ° C. is preferably 1000 ppm or less, more preferably 400 ppm or less, and even more preferably 100 ppm or less, from the viewpoint of improving static flex resistance and dynamic flex resistance. Among them, the content of the organic solvent having a boiling point of 60 ° C. or less may be 2000 ppm or less, preferably 1000 ppm or less, more preferably 400 ppm or less, and even more preferably 100 ppm or less. The content of the organic solvent having a boiling point of less than 100 ° C. is preferably as small as possible and may be 0 ppm from the viewpoint of improving the static bending resistance and the dynamic bending resistance.
On the other hand, the content of the organic solvent having a boiling point of 100 ° C. or more is preferably 80 ppm or less, more preferably 50 ppm or less, still more preferably 30 ppm or less, and even more preferably 20 ppm or less, from the viewpoint of improving the dynamic bending resistance. The content of the organic solvent having a boiling point of 100 ° C. or higher is preferably as small as possible from the viewpoint of improving the dynamic bending resistance, and may be 0 ppm.
The content of the organic solvent having a boiling point under 1 atm of 70 ° C. or less may be 2000 ppm or less, and the content of the organic solvent having a boiling point under 1 atm of more than 70 ° C. may be 100 ppm or less. The content of the organic solvent having a boiling point at 1 atm of 60 ° C. or less may be 2000 ppm or less, and the content of the organic solvent having a boiling point at 1 atm of more than 60 ° C. may be 100 ppm or less, and furthermore The content of the organic solvent having a boiling point of 50 ° C. or less at 1 atm may be 2000 ppm or less, and the content of the organic solvent having a boiling point of more than 50 ° C. at 1 atm may be 100 ppm or less.

Examples of the organic solvent having a boiling point of less than 100 ° C. at 1 atm contained as a residual solvent include organic solvents used in the process of producing a polyimide film. Examples of the organic solvent include chloroform, carbon tetrachloride, 1,2-dichloroethane, and 1,2-dichloroethane. , 2-dichloroethylene, trichloroethylene, acetone, isopropyl alcohol, diethyl ether, isopropyl acetate, ethyl acetate, methyl acetate, dichloromethane, tetrahydrofuran, 1,1,1-trichloroethane, normal hexane, 2-butanol, methanol, methyl ethyl ketone and the like. Among them, as the organic solvent having a boiling point of 70 ° C. or less at 1 atm, chloroform, 1,2-dichloroethylene, acetone, diethyl ether, methyl acetate, dichloromethane, tetrahydrofuran, normal hexane, meta Lumpur, and the like.
Examples of the organic solvent having a boiling point of 100 ° C. or more at 1 atm included in the residual solvent include organic solvents used in the process of producing a polyimide film. Examples thereof include N-methyl-2-pyrrolidone and N, N-dimethyl. Formamide, N, N-dimethylacetamide, dimethylsulfoxide, hexamethylphosphoramide, 1,3-dimethyl-2-imidazolidinone, γ-butyrolactone, propylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether, ethylene glycol monoethyl Ether acetate, ethylene glycol mono-normal-butyl ether, ethylene glycol monomethyl ether, ortho-dichlorobenzene, xylene, ortho-cresol, chlorobenzene, isobutyl acetate, isopentyl acetate Normal-butyl acetate, normal-propyl acetate, normal-pentyl acetate, normal-butyl acetate, cyclohexanol, cyclohexanone, 1,4-dioxane, tetrachloroethylene, toluene, methyl isobutyl ketone, methylcyclohexanol, methylcyclohexanone, methyl-normal- Butyl ketone and the like.

The residual solvent amount of the polyimide film can be measured as follows.
[Specification of residual solvent type]
First, the type of the residual solvent is specified using a GC-MS to which a purge & trap device (heat desorption device) is connected.
A sample tube containing 10 mg of a polyimide film was set in a purge & trap device (product name: JTD505-III, Nippon Kagaku Kogyo Co., Ltd.), and the gas generated by heating at 200 ° C. for 30 minutes was heated to −60 ° C. Are collected at a temperature of 315 ° C. and are then sent to a GC-MS for qualitative analysis of the components of the generated organic gas.
(Purge & trap equipment conditions)
1:10 total split ratio (introduction / displacement)
Carrier gas helium 1.0ml / min quantitative (GC-MS condition)
Apparatus name: GC-MS apparatus (Agilent, 6890/5973 GC / MS)
Column: UA-5 Inner diameter 250 μm × Length 30 m × Film thickness 0.25 μm (Frontier Lab) )

[Quantification of residual solvent]
A polyimide film is added to N, N-dimethylformamide (DMF) so that the concentration of the polyimide film is 5% by mass, and a polyimide film / N, N-dimethylformamide (DMF) solution is prepared. , An internal standard solution (0.2% by mass anisole / DMF solution) is added to prepare a sample solution. The sample solution is subjected to a GC-MS measurement using a GC-MS device (for example, Agilent, 6890/5973 GC / MS) under the following conditions. The GC-MS measurement is performed three times, and the measurement result is an average value of the three measurements.
(GC conditions)
Column: InertCapWax inner diameter 250 μm × length 30 m × film thickness 0.25 μm (manufactured by GL Sciences)
Sample injection amount 0.2uL, split ratio (introduction amount / evacuation amount) 1:50, carrier gas helium 94.3kPa constant pressure, injection port temperature 250 ° C, heating condition 40 ° C (5 minutes holding) → 5 ° C / min → 120 ° C → 20 ° C / min → 240 ° C (hold for 6 minutes), transfer line temperature 250 ° C
(MS condition)
Ionization method EI, measurement mode SIM, ion source temperature 250 ° C, quadrupole temperature 150 ° C, ionization voltage 70eV

A calibration curve is created for each residual solvent specified as described above, and the amount of each residual solvent is quantified based on the calibration curve.
For example, when the contained residual solvent is N, N-dimethylacetamide (DMAc), the DMAc content was adjusted to, for example, 0.01% by mass, 0.05% by mass, and 0.1% by mass, respectively. A GC-MS measurement is performed on each calibration curve solution prepared by adding an internal standard solution to each DMAc (measurement target compound) / DMF solution in the same manner as the above-mentioned sample solution, and a calibration curve is created. Note that the GC-MS measurement is performed three times, and the measurement result is an average value of the three measurements.
Then, based on the calibration curve, the content of DMAc is calculated as a mass ratio to the polyimide film. Note that the calibration curve is re-created as appropriate based on the detected amount.
When there are two or more kinds of residual solvents contained, a calibration curve solution is prepared for each residual solvent as in the above-mentioned DMAc, and a calibration curve created from the measurement results of each calibration curve solution by GC-MS measurement. Based on line.
When N, N-dimethylformamide (DMF) is contained as a residual solvent, a sample solution is prepared using a good polyimide solvent not contained as a residual solvent, for example, N-methyl-2-pyrrolidone. .

(2) Total light transmittance
In addition, the polyimide film of the present invention has a total light transmittance of 85% or more as measured according to JIS K7361-1. Since the transmittance is high as described above, the transparency is improved and the glass can be used as a substitute material for glass. The total light transmittance of the polyimide film of the present invention measured in accordance with JIS K7361-1 is preferably 88% or more, more preferably 89% or more, and particularly preferably 90% or more. Is preferred.

The total light transmittance measured according to JIS K7361-1 can be measured by, for example, a haze meter (for example, HM150 manufactured by Murakami Color Research Laboratory). In addition, from the measured value of the total light transmittance of a certain thickness, the converted value of the total light transmittance of a different thickness can be obtained by Lambert-Beer's law and can be used.
Specifically, according to Lambert-Beer's law, the transmittance T is
Log ₁₀ (1 / T) = kcb
(K = constant peculiar to the substance, c = concentration, b = optical path length).
For the transmittance of the film, so even if the film thickness is changed density is also constant c assuming a constant, the above formula, Log 10 using constants f _{(1 / T)} = fb
(F = kc). Here, if the transmittance at a certain film thickness is known, a unique constant f of each substance can be obtained. Therefore, the transmittance at a desired film thickness can be obtained by substituting a constant specific to f and a target film thickness into b using the equation of T = 1/10 ^{f · b} .

(3) Yellowness The polyimide film of the present invention preferably has a yellowness (YI value) of 12 or less, calculated based on JIS K7373-2006. When the degree of yellowness is low as described above, coloring of yellowish color is suppressed, light transmittance is improved, and the glass can be used as a glass substitute material. The yellowness (YI value) calculated according to JIS K7373-2006 is preferably 10 or less, more preferably 7 or less, and even more preferably 5 or less.
In addition, the yellowness (YI value) is measured by a spectrophotometric method using an ultraviolet-visible-near-infrared spectrophotometer (for example, JASCO Corporation V-7100) in accordance with JIS K7373-2006. Using the illuminant C and a two-degree visual field, tristimulus values X, Y, and Z in the XYZ color system are obtained based on the transmittance measured in the range of 250 nm or more and 800 nm or less at 1 nm intervals. , Z can be calculated from the following equation.
YI = 100 (1.2767X-1.0592Z) / Y
In addition, from the measured value of the yellowness of a certain thickness, the yellowness of a different thickness is obtained by measuring the total transmittance at each wavelength measured at 1 nm intervals between 250 nm and 800 nm of a sample having a specific thickness. As in the case of the light transmittance, a converted value of each transmittance at each wavelength having a different thickness is obtained by Lambert-Beer's law, and can be calculated and used based on the converted value.

In addition, the polyimide film of the present invention has a yellow color calculated based on JIS K7373-2006 from the viewpoint that coloring of yellow tint is suppressed, light transmittance is improved, and it can be suitably used as a glass substitute material. The value (YI value / film thickness (μm)) obtained by dividing the degree (YI value) by the film thickness (μm) is preferably 0.10 or less, more preferably 0.04 or less, and 0.03 or less. It is even more preferred that:
In the present invention, the value obtained by dividing the yellowness (YI value) by the film thickness (μm) (YI value / film thickness (μm)) is in the second decimal place according to JIS Z8401: 1999 Rule B. Use the rounded value.

(4) Tensile modulus
The polyimide film of the present invention has a tensile modulus at 25 ° C. of 1.8 GPa or more when a 15 mm × 40 mm test piece is measured according to JIS K7127 at a tensile speed of 10 mm / min and a distance between chucks of 20 mm. Is preferred. When the tensile modulus at 25 ° C. (room temperature) is high, sufficient surface hardness as a protective film can be maintained even at room temperature, and the protective film can be used as a surface material or a substrate. The tensile modulus is preferably 2.0 GPa or more, more preferably 2.1 GPa or more, and even more preferably 2.3 GPa or more. On the other hand, the tensile modulus is preferably 5.2 GPa or less from the viewpoint of improving the bending resistance. From the viewpoint of improving the bending resistance, the tensile modulus may be 4.0 GPa or less, 3.5 GPa or less, or 2.9 GPa or less.
The tensile elasticity was determined by cutting a 15 mm wide × 40 mm long test piece from a polyimide film using a tensile tester (for example, Autograph AG-X 1N, load cell: SBL-1KN, manufactured by Shimadzu Corporation) at 25 ° C. It can be measured with a pulling speed of 8 mm / min and a distance between chucks of 20 mm. It is preferable that the polyimide film for determining the tensile modulus has a thickness of 55 μm ± 5 μm.

(5) Tan δ Curve The polyimide film of the present invention preferably has a peak apex only in a temperature region of 150 ° C. or higher in a tan δ curve obtained by dividing a loss elastic modulus by a storage elastic modulus. In the tan δ curve, when the peak apex is present at less than 150 ° C., the molecular chain of the polyimide is likely to move, plastic deformation is likely to occur, and the bending resistance may be deteriorated, whereas the peak apex is less than 150 ° C. This is because, if it does not exist, the mobility of the molecular chain is suppressed, plastic deformation becomes difficult, and bending resistance can be improved.
Further, in the tan δ curve, when the peak apex is located only in a temperature region of 150 ° C. or higher, even under a high temperature environment, for example, in a summer car, the bending resistance is suppressed from being impaired by thermal deformation. Bending resistance is improved even under an environment.
When the peak of the tan δ curve has a peak only in a temperature range of 150 ° C. or higher, the tensile modulus tends to increase, and the surface hardness tends to increase.
From the viewpoint of improving the bending resistance and surface hardness, the polyimide film of the present invention more preferably has the peak apex only in the temperature region of 200 ° C. or higher in the tan δ curve, and has a temperature region of 220 ° C. or higher. It is even more preferred that the compound has only On the other hand, from the viewpoint that the baking temperature can be reduced, the peak of the peak in the tan δ curve is preferably in a temperature range of 380 ° C. or less.
Further, the polyimide film of the present invention, among others, in a temperature region of -150 ° C or more and less than 150 ° C, further, in a temperature region of -70 ° C or more and less than 150 ° C, preferably does not have a peak apex in the tan δ curve. Further, it is preferable that the tan δ curve has no peak apex in a temperature range of 100 ° C. or less, and it is more preferable that the tan δ curve has no peak apex in a temperature range of 0 ° C. or less. When the main chain has a diamine residue having a long siloxane bond or when the main chain contains a large amount of a diamine residue having a silicon atom, when the peak of the peak in the tan δ curve is in such a low temperature region There is.
The tan δ curve is obtained from the relationship between temperature and tan δ (tan δ = loss modulus (E ″) / storage modulus (E ′)) by dynamic viscoelasticity measurement, and the maximum value of the peak is the maximum. Can be used as an index of the glass transition temperature. The dynamic viscoelasticity measurement is performed by, for example, using a dynamic viscoelasticity measuring device RSA-G2 (TA Instruments Japan Co., Ltd.), setting the measurement range to −150 ° C. or more and 490 ° C. or less, and increasing the frequency to 1 Hz. It can be performed at a temperature rate of 5 ° C./min. The measurement can be performed with a sample width of 5 mm and a chuck-to-chuck distance of 20 mm. When analyzing peaks and inflection points, data is digitized and analyzed from numerical values without visual evaluation.
In the curve of temperature (horizontal axis) and tan δ (tan δ = loss modulus (E ″) / storage modulus (E ′)) (vertical axis), the peak means that the value of tan δ is 0.2 or more, It is preferably 0.3 or more and has a maximum value, and a peak width between valleys of peaks is 3 ° C. or more. , Is not observed as the peak at the top of the peak.
As a sample for measuring a tan δ curve, a polyimide film which was left standing for 24 hours in an environment of 23 ° C. ± 2 ° C. RH 30 to 50% was sampled into a square of 10 cm or more. Using a cutting jig with a slit, a cutout having a width of 5 mm and a length of 50 mm (so that the sample length becomes 20 mm at the time of chucking) is used. The width is measured using a caliper, and the average value measured three times at different positions is recorded. At this time, if a part of the width measurement has a fluctuation width of 3% or more of the average value, the sample is not used.

(6) Pencil hardness In the polyimide film of the present invention, the pencil hardness is preferably 2B or more, more preferably B or more, and even more preferably HB or more.
The pencil hardness of the polyimide film is determined by adjusting the humidity of a measurement sample at a temperature of 25 ° C. and a relative humidity of 60% for 2 hours, and then using a test pencil specified by JIS-S-6006 according to JIS K5600-5-4. This can be performed by performing a pencil hardness test (load of 0.98 N) specified in (1999) on the film surface and evaluating the highest pencil hardness that does not damage the film. For example, a pencil scratching film hardness tester manufactured by Toyo Seiki Co., Ltd. can be used.

(7) Adhesion of Film Also, in the polyimide film of the present invention, when the adhesion test is carried out according to the following adhesion test method, the peeling of the coating film does not occur. From the viewpoint of adhesion and the surface hardness of a laminate in which a hard coat layer is laminated adjacent to a polyimide film.
[Adhesion test method]
Adhesion evaluation resin composition prepared by adding 10 parts by mass of 1-hydroxy-cyclohexyl-phenyl-ketone to 100 parts by mass of pentaerythritol triacrylate to a 40% by mass solution of pentaerythritol triacrylate in methyl isobutyl ketone Is applied on a test piece of a polyimide film cut into a size of 10 cm × 10 cm, and is cured by irradiating ultraviolet rays at a light exposure of 200 mJ / cm ² under a nitrogen stream to form a cured film having a thickness of 10 μm. The cured film is subjected to a cross-cut test in accordance with JIS K 5600-5-6, and a peeling operation using a tape is repeated five times, and then the presence or absence of peeling of the coating film is observed.

4. Structure of the polyimide film The thickness of the polyimide film of the present invention may be appropriately selected depending on the application, but is preferably 1 μm or more, more preferably 5 μm or more, and still more preferably 10 μm or more. . On the other hand, it is preferably 200 μm or less, more preferably 150 μm or less, further more preferably 100 μm or less, and still more preferably 90 μm or less.
If the thickness is small, the strength is reduced. If the thickness is large, the difference between the inner diameter and the outer diameter at the time of bending is increased, and the load on the film is increased, so that the bending resistance may be reduced.

  Further, the polyimide film of the present invention may be subjected to a surface treatment such as a saponification treatment, a glow discharge treatment, a corona discharge treatment, an ultraviolet treatment, a flame treatment, and the like.

5. Method for Producing Polyimide Film The method for producing the polyimide film of the present invention is not particularly limited as long as it can produce the polyimide film of the present invention.
<First manufacturing method>
As a method for producing the polyimide film of the present invention, for example, as a first production method,
A step of preparing a polyimide precursor resin composition containing a polyamic acid that is a polyimide precursor and an organic solvent (hereinafter, referred to as a polyimide precursor resin composition preparation step),
A step of applying the polyimide precursor resin composition to a support to form a polyimide precursor resin coating film (hereinafter, referred to as a polyimide precursor resin coating film forming step);
A step of imidizing the polyimide precursor by heating (hereinafter, referred to as an imidation step);
And a method for producing a polyimide film containing the same.
In the method for producing a polyimide film of the present invention, further, the residual solvent amount of the obtained polyimide film is measured, and as a residual solvent in the film, the content of an organic solvent having a boiling point under 1 atmosphere of less than 100 ° C. It is preferable to include a step of determining whether or not the content of the organic solvent having a boiling point of not more than 2000 ppm and a pressure of not less than 100 ° C. under 1 atm is not more than 100 ppm. If the residual solvent amount of the obtained polyimide film exceeds the value specified in the present invention, by further performing a step of heating the polyimide film, the residual solvent amount of the polyimide film was specified in the present invention. It is preferable to set the value equal to or less than the value.

In the first manufacturing method, further, a step of stretching at least one of the polyimide precursor resin coating film and an imidized coating film obtained by imidizing the polyimide precursor resin coating film (hereinafter referred to as a stretching step) ) May be included.
Hereinafter, each step will be described in detail.

(1) Polyimide precursor resin composition preparation step The polyimide precursor resin composition prepared in the first production method contains a polyimide precursor and an organic solvent, and optionally contains additives and the like. May be. Examples of the polyimide precursor include a polyimide precursor represented by the following general formula (1 ′). The polyimide precursor represented by the general formula (1 ′) includes a tetracarboxylic acid component serving as a tetracarboxylic acid residue in R ¹ of the general formula (1 ′) and R ^{2 of the} general formula (1 ′). Is a polyamic acid obtained by polymerization with a diamine component to be a diamine residue in the above.

(In the general formula (1 ′), R ¹ , R ² and n are the same as those in the general formula (1).)

Here, as R ¹ , R ² and n in the general formula (1 ′), those similar to R ¹ , R ² and n in the general formula (1) described in the polyimide can be used.

The polyimide precursor represented by the general formula (1 ′) preferably has at least one of a number average molecular weight and a weight average molecular weight of 10,000 or more from the viewpoint of strength when formed into a film, and more preferably 20,000. It is preferable that it is above. Further, the polyimide precursor represented by the general formula (1 ′) preferably has a weight average molecular weight of 70,000 or more, more preferably 80,000 or more, from the viewpoint of improving bending resistance. It is preferably 85,000 or more.
On the other hand, if the average molecular weight is too large, the viscosity is high, and the workability such as filtration may be reduced. Therefore, the average molecular weight is preferably 1000000 or less, more preferably 500,000 or less.
The number average molecular weight of the polyimide precursor can be determined by NMR (for example, AVANCE III manufactured by BRUKER). For example, after applying a polyimide precursor solution to a glass plate and drying at 100 ° C. for 5 minutes, 10 mg of a solid content is dissolved in 7.5 ml of dimethyl sulfoxide-d6 solvent, NMR measurement is performed, and the compound is bonded to an aromatic ring. The number average molecular weight can be calculated from the peak intensity ratio of hydrogen atoms.
The weight average molecular weight of the polyimide precursor can be measured by gel permeation chromatography (GPC).
The polyimide precursor was an N-methylpyrrolidone (NMP) solution having a concentration of 0.5% by weight, and a developing solvent was a 10 mmol% LiBr-NMP solution having a water content of 500 ppm or less. Column: GPC LF-804 manufactured by SHOdex), and measurement is performed under the conditions of a sample injection amount of 50 μL, a solvent flow rate of 0.5 mL / min, and 40 ° C. The weight average molecular weight is determined based on a polystyrene standard sample having the same concentration as the sample.

  The polyimide precursor solution is obtained by reacting the above-mentioned tetracarboxylic dianhydride with the above-mentioned diamine in a solvent. The solvent used for the synthesis of the polyimide precursor (polyamic acid) is not particularly limited as long as it can dissolve the above-mentioned tetracarboxylic dianhydride and diamine. For example, an aprotic polar solvent or a water-soluble alcohol solvent can be used. Can be used. In the present invention, among others, N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, dimethylsulfoxide, hexamethylphosphoramide, 1,3-dimethyl-2-imidazolidinone and the like It is preferable to use an organic solvent containing a nitrogen atom of γ-butyrolactone. In particular, when the polyimide precursor solution (polyamic acid solution) is used as it is for the preparation of the polyimide precursor resin composition, it is preferable to use an organic solvent containing a nitrogen atom, among which N, N-dimethylacetamide, N- It is preferable to use methyl-2-pyrrolidone or a combination thereof. Note that the organic solvent is a solvent containing a carbon atom.

When the polyimide precursor solution is prepared by combining at least two diamines, an acid dianhydride may be added to a mixed solution of at least two diamines to synthesize a polyamic acid, The two diamine components may be added to the reaction solution stepwise at an appropriate molar ratio to control the sequence in which each raw material is incorporated into the polymer chain to some extent.
For example, an acid dianhydride having a molar ratio of 0.5 equivalent of a diamine having a silicon atom in the main chain is added to a reaction solution in which a diamine having a silicon atom in the main chain is dissolved, and the reaction is performed. Synthesize an amic acid in which a diamine having a silicon atom in the main chain at both ends of the anhydride is reacted, and then, all or a part of the remaining diamine is added thereto, and an acid dianhydride is added to polymerize the polyamic acid. Is also good. When polymerized by this method, a diamine having a silicon atom in the main chain is introduced into the polyamic acid in a linked form via one acid dianhydride.
Polymerizing the polyamic acid by such a method is preferable because the positional relationship of the amic acid having a silicon atom in the main chain is specified to some extent, and it is easy to obtain a film having excellent bending resistance while maintaining the surface hardness.

When the number of moles of diamine in the polyimide precursor solution (polyamic acid solution) is a and the number of moles of tetracarboxylic dianhydride is b, b / a may be 0.9 or more and 1.1 or less. It is more preferably 0.95 or more and 1.05 or less, further preferably 0.97 or more and 1.03 or less, and particularly preferably 0.99 or more and 1.01 or less. The molecular weight (degree of polymerization) of the obtained polyamic acid can be appropriately adjusted by setting the content in such a range.
The procedure of the polymerization reaction can be appropriately selected from known methods, and is not particularly limited.
Alternatively, the polyimide precursor solution obtained by the synthesis reaction may be used as it is, and other components may be mixed as necessary, or the solvent of the polyimide precursor solution may be dried and dissolved in another solvent. May be used.

The viscosity of the polyimide precursor solution at 25 ° C. is preferably 500 cps to 200,000 cps from the viewpoint of forming a uniform coating film and a polyimide film.
The viscosity of the polyimide precursor solution can be measured at 25 ° C. using a viscometer (for example, TVE-22HT, Toki Sangyo Co., Ltd.).

  The polyimide precursor resin composition may contain an additive as needed. Examples of the additive include, for example, inorganic particles for reducing optical distortion of the polyimide film, silica filler for smooth winding, and a surfactant for improving film forming property and defoaming property. Thus, the same one as described in the above-mentioned polyimide film can be used.

  The organic solvent used for the polyimide precursor resin composition is not particularly limited as long as the polyimide precursor can be dissolved. For example, it contains a nitrogen atom such as N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, dimethylsulfoxide, hexamethylphosphoramide, 1,3-dimethyl-2-imidazolidinone and the like. Organic solvent; γ-butyrolactone and the like can be used, and among them, it is preferable to use an organic solvent containing a nitrogen atom for the above-mentioned reason.

The content of the polyimide precursor in the polyimide precursor resin composition is 50% by mass or more in the solid content of the resin composition from the viewpoint of forming a uniform coating film and a polyimide film having handleable strength. It is preferable that the content is not less than 60% by mass, and the upper limit may be appropriately adjusted depending on the contained components.
From the viewpoint of forming a uniform coating film and a polyimide film, the organic solvent in the polyimide precursor resin composition is preferably 40% by mass or more in the resin composition, and more preferably 50% by mass or more. It is preferably 99% by mass or less.

Further, the polyimide precursor resin composition preferably has a water content of 1000 ppm or less from the viewpoint that the storage stability of the polyimide precursor resin composition becomes good and the productivity can be improved. If the polyimide precursor resin composition contains a large amount of water, the polyimide precursor may be easily decomposed.
The moisture content of the polyimide precursor resin composition can be determined using a Karl Fischer moisture meter (for example, a trace moisture meter CA-200, manufactured by Mitsubishi Chemical Corporation).

The viscosity of the polyimide precursor resin composition at a solid content of 15% by weight at 25 ° C. is preferably 500 cps to 100,000 cps from the viewpoint of forming a uniform coating film and a polyimide film.
The viscosity of the polyimide precursor resin composition can be measured using a viscometer (for example, TVE-22HT, Toki Sangyo Co., Ltd.) at 25 ° C. with a sample volume of 0.8 ml.

(2) Polyimide precursor resin coating film forming step In the step of applying the polyimide precursor resin composition to a support to form a polyimide precursor resin coating film, the support used has a smooth surface and heat resistance. There is no particular limitation as long as the material has water resistance and solvent resistance. For example, an inorganic material such as a glass plate, a metal plate whose surface is mirror-finished, and the like can be given. The shape of the support is selected according to the coating method, and may be, for example, a plate, a drum, a belt, a sheet that can be wound up on a roll, or the like.

The coating means is not particularly limited as long as it is a method capable of coating with a desired film thickness. For example, a known means such as a die coater, a comma coater, a roll coater, a gravure coater, a curtain coater, a spray coater, and a lip coater can be used. .
The coating may be performed by a single-wafer coating device or a roll-to-roll coating device.

  After applying the polyimide precursor resin composition to the support, the solvent in the coating is dried at a temperature of 150 ° C. or lower, preferably 30 ° C. or higher and 120 ° C. or lower until the coating is tack-free. By setting the drying temperature of the solvent to 150 ° C. or lower, imidization of the polyamic acid can be suppressed.

  The drying time may be appropriately adjusted according to the thickness of the polyimide precursor resin coating film, the type of solvent, the drying temperature, and the like, and is usually 1 minute to 60 minutes, preferably 2 minutes to 30 minutes. Is preferred. Exceeding the upper limit is not preferable from the viewpoint of the production efficiency of the polyimide film. On the other hand, when the value is below the lower limit, rapid drying of the solvent may affect the appearance and the like of the obtained polyimide film.

The method for drying the solvent is not particularly limited as long as the solvent can be dried at the above temperature. For example, an oven, a drying furnace, a hot plate, infrared heating, or the like can be used.
When a high degree of control of the optical properties is required, the atmosphere at the time of drying the solvent is preferably an inert gas atmosphere. The inert gas atmosphere is preferably a nitrogen atmosphere, and the oxygen concentration is preferably 100 ppm or less, more preferably 50 ppm or less. When heat treatment is performed in the atmosphere, the film may be oxidized, colored, or deteriorate in performance.

(3) Imidation step In the first production method, the polyimide precursor is imidized by heating.
In the present invention, to reduce the residual solvent amount of the polyimide film to the value specified in the present invention or less, by peeling the polyimide precursor resin coating from the support used when applying, by heating, It is preferable to perform a step of imidizing the polyimide precursor. By peeling off from the support used at the time of coating and heating the film in a state where both surfaces of the film are not in contact with the support or the like, the solvent can be volatilized from both surfaces of the film, and the residual solvent is removed by the present invention. Can be sufficiently reduced below the value specified in.
Further, the polyimide precursor resin coating film after peeling from the support is preferably heated after fixing the end portion in order to prevent shrinkage during heating.
As a method of fixing the end of the polyimide precursor resin coating, for example, if the polyimide precursor resin coating is sheet-like, metal having approximately the same outer dimensions and appropriate inner dimensions as the polyimide precursor resin coating There is a method in which two frames are used to sandwich the polyimide precursor resin coating film, and the two metal frames and the polyimide precursor resin coating film are fixed with a fixing jig.
Further, for example, when the polyimide precursor resin coating film is in the form of a roll, for example, using a device capable of transporting the resin film by holding the left and right ends of a continuous resin film with a fixing jig such as a clip, the polyimide precursor There is a method of fixing the end of the resin coating film.

  In the manufacturing method, when a stretching step is included, the imidization step may be performed on the polyimide precursor in the polyimide precursor resin coating film before the stretching step, or the polyimide precursor resin after the stretching step It may be performed on the polyimide precursor in the coating film, and both the polyimide precursor in the polyimide precursor resin coating film before the stretching step and the polyimide precursor present in the film after the stretching step You may go.

The imidization temperature may be appropriately selected according to the structure of the polyimide precursor.
Usually, the temperature rise start temperature is preferably 30 ° C. or higher, more preferably 100 ° C. or higher. On the other hand, the temperature rise end temperature is preferably set to 250 ° C. or higher, more preferably 270 ° C. or higher. On the other hand, from the viewpoint of suppressing the appearance failure and the decrease in strength of the film and improving the light transmittance, the temperature raising end temperature is preferably 400 ° C. or lower, more preferably 350 ° C. or lower.

The rate of temperature rise is preferably selected as appropriate depending on the thickness of the polyimide film to be obtained. When the thickness of the polyimide film is large, the rate of temperature rise is preferably reduced.
From the viewpoint of the production efficiency of the polyimide film, the temperature is preferably 5 ° C / min or more, more preferably 10 ° C / min or more. On the other hand, the upper limit of the heating rate is usually 50 ° C./min, preferably 40 ° C./min or less, more preferably 30 ° C./min or less. The above-mentioned rate of temperature increase is preferable from the viewpoint that the appearance of the film and the reduction in the strength of the film can be suppressed, the whitening accompanying the imidization reaction can be controlled, and the light transmittance is improved.

  The temperature may be raised continuously or stepwise. However, it is preferable that the temperature be raised continuously from the viewpoint of suppressing the poor appearance and the decrease in the strength of the film and controlling the whitening accompanying the imidization reaction. Further, in the above-mentioned entire temperature range, the heating rate may be constant or may be changed in the middle.

It is preferable that the atmosphere at the time of the temperature rise of the imidization is an inert gas atmosphere. The inert gas atmosphere is preferably a nitrogen atmosphere, and the oxygen concentration is preferably 500 ppm or less, more preferably 200 ppm or less, and even more preferably 100 ppm or less. When heat treatment is performed in the atmosphere, the film may be oxidized, colored, or deteriorate in performance.
However, when 50% or more of the hydrogen atoms bonded to the carbon atoms contained in the polyimide are hydrogen atoms directly bonded to the aromatic ring, the influence of oxygen on optical characteristics is small, and an inert gas atmosphere can be used. Also, a polyimide having high light transmittance can be obtained.

  The heating method for imidization is not particularly limited as long as the temperature can be raised at the above temperature, and for example, an oven, a heating furnace, infrared heating, electromagnetic induction heating, or the like can be used.

Above all, it is more preferable that the imidation ratio of the polyimide precursor be 50% or more before the stretching step. By setting the imidation ratio to 50% or more before the stretching step, stretching is performed after the step, and then heating is performed at a higher temperature for a certain period of time. Whitening is suppressed. Above all, from the viewpoint of improving the surface hardness of the polyimide film, it is preferable that the imidization ratio is set to 80% or more in the imidization step before the stretching step, and the reaction proceeds to 90% or more, and further to 100%. Is preferred. It is presumed that the surface hardness is improved by stretching after imidization because the rigid polymer chains are easily oriented.
The imidation ratio can be measured by analyzing the spectrum by infrared measurement (IR) or the like.

In order to obtain a final polyimide film, it is preferable that the reaction proceeds to 90% or more, more preferably 95% or more, and even 100% of imidization.
In order to allow the reaction to proceed to 90% or more, and more preferably to 100% of the imidization, it is preferable to keep the temperature at the end of the heating for a certain period of time. Minutes.

(4) Stretching Step The first manufacturing method includes a stretching step of stretching at least one of the polyimide precursor resin coating film and a post-imidation coating film obtained by imidizing the polyimide precursor resin coating film. It may be. In the case where the stretching step is provided, it is particularly preferable to include a step of stretching the coating film after imidization from the viewpoint of improving the surface hardness of the polyimide film.

In the first manufacturing method, it is preferable to perform the step of stretching from 101% to 10000% when the initial size before stretching is set to 100% while heating at 80 ° C or more.
The heating temperature during stretching is preferably within the range of the glass transition temperature of the polyimide or the polyimide precursor ± 50 ° C., and more preferably within the range of the glass transition temperature ± 40 ° C. If the stretching temperature is too low, the film may not be deformed and orientation may not be sufficiently induced. On the other hand, if the stretching temperature is too high, the orientation obtained by the stretching may be relaxed at the temperature, and a sufficient orientation may not be obtained.
The stretching step may be performed simultaneously with the imidization step. Stretching the coating film after imidization after imidization ratio of 80% or more, further 90% or more, even more 95% or more, particularly substantially 100%, improves the surface hardness of the polyimide film. Preferred from the point.

  The stretch ratio of the polyimide film is preferably from 101% to 10,000%, more preferably from 101% to 500%. By performing stretching within the above range, the surface hardness of the obtained polyimide film can be further improved.

  The method of fixing the polyimide film at the time of stretching is not particularly limited, and is selected according to the type of the stretching apparatus. The stretching method is not particularly limited. For example, it is possible to perform stretching while passing through a heating furnace using a stretching apparatus having a transport device such as a tenter. The polyimide film may be stretched in only one direction (longitudinal stretching or transverse stretching), or may be stretched in two directions by simultaneous biaxial stretching, sequential biaxial stretching, oblique stretching, or the like.

<Second manufacturing method>
Further, as a method for producing a polyimide film of the present invention, as a second production method,
A step of preparing a polyimide resin composition containing polyimide and an organic solvent (hereinafter, referred to as a polyimide resin composition preparation step);
A method of forming a polyimide resin coating film by applying the polyimide resin composition to a support and drying a solvent (hereinafter, referred to as a polyimide resin coating film forming step).

When the polyimide is well dissolved in an organic solvent, not the polyimide precursor resin composition, the polyimide is dissolved in an organic solvent, and a polyimide resin composition containing an additive as needed is preferably used. be able to.
When the polyimide has a solvent solubility of 5% by mass or more in an organic solvent at 25 ° C., the production method can be preferably used.
In the present invention, a polyimide used for producing a polyimide film may be referred to as a polyimide material. The polyimide material is a polyimide that may contain a residual solvent in a predetermined amount or less.

In the second method for producing a polyimide film of the present invention, before the step of preparing the polyimide resin composition, the residual solvent amount of the polyimide (polyimide material) used is measured, and the boiling point at 1 atm. It is preferable to have a step of determining whether the content of the organic solvent having a boiling point of less than 100 ° C. is 2000 ppm or less and the content of the organic solvent having a boiling point at 100 ° C. or more at 1 atm is 100 ppm or less. When the residual solvent amount of the polyimide (polyimide material) used exceeds the value specified in the present invention, the residual solvent amount of the polyimide (polyimide material) used is further reduced by using a washing step described later. It is preferable to include a step of reducing the value to the value specified in or less.
The polyimide used in the step of preparing the polyimide resin composition has a structure represented by the general formula (1), and as a residual solvent, an organic solvent having a boiling point of less than 100 ° C. at 1 atm. It is preferable to use a polyimide material having a content of 2000 ppm or less and an organic solvent having a boiling point of 100 ° C. or more at 1 atm or less of 100 ppm or less.
In the polyimide material, the content of the organic solvent having a boiling point of less than 100 ° C. is preferably 1,000 ppm or less, more preferably 400 ppm or less, and still more preferably 100 ppm or less, from the viewpoint of improving static flex resistance and dynamic flex resistance. . On the other hand, the content of the organic solvent having a boiling point of 100 ° C. or more is preferably 80 ppm or less, more preferably 50 ppm or less, still more preferably 30 ppm or less, and even more preferably 20 ppm or less, from the viewpoint of improving the dynamic bending resistance.
Even in the polyimide material, the content of the organic solvent having a boiling point of 70 ° C. or less at 1 atm is 2,000 ppm or less, and the content of the organic solvent having a boiling point of more than 70 ° C. at 1 atm is 100 ppm or less. Further, the content of the organic solvent having a boiling point under 1 atm of 60 ° C. or less is 2000 ppm or less, and the content of the organic solvent having a boiling point under 1 atm of more than 60 ° C. is 100 ppm or less, Further, the content of the organic solvent having a boiling point at 1 atm of 50 ° C. or less is 2,000 ppm or less, and the content of the organic solvent having a boiling point at 1 atm of more than 50 ° C. is 100 ppm or less. You may.
Further, in the second method for producing a polyimide film of the present invention, the amount of the residual solvent in the obtained polyimide film is further measured, and the residual solvent in the film is an organic solvent having a boiling point under 1 atm. It is preferable to include a step of determining whether the content of the solvent is 2000 ppm or less and the content of the organic solvent having a boiling point at 100 ° C. or more at 1 atm is 100 ppm or less. If the residual solvent amount of the obtained polyimide film exceeds the value specified in the present invention, by further performing a step of heating the polyimide film, the residual solvent amount of the polyimide film was specified in the present invention. It is preferable to set the value equal to or less than the value.

In the polyimide resin composition preparation step, the polyimide having the above-mentioned solvent solubility can be selected from the same polyimides as those described for the polyimide film.
As a method of imidization, it is preferable to use chemical imidization using a chemical imidizing agent instead of heat dehydration for the dehydration ring closure reaction of the polyimide precursor. In the case of performing chemical imidization, known compounds such as amines such as pyridine and β-picolinic acid, carbodiimides such as dicyclohexylcarbodiimide, and acid anhydrides such as acetic anhydride may be used as a dehydration catalyst. The acid anhydride is not limited to acetic anhydride, and includes, but is not particularly limited to, propionic anhydride, n-butyric anhydride, benzoic anhydride, trifluoroacetic anhydride and the like. In this case, a tertiary amine such as pyridine or β-picolinic acid may be used in combination. However, these amines reduce optical properties, particularly yellowness (YI value) when remaining in the film. It is preferable to purify by reprecipitation or the like, and to remove the components other than the polyimide to 100 ppm or less of the total weight of the polyimide before forming the film.

  In the polyimide resin composition preparing step, as the organic solvent used in the reaction solution for chemically imidizing the polyimide precursor, for example, those described in the polyimide precursor resin composition preparing step in the first production method Similar ones can be used.

Further, as the organic solvent used when purifying the reaction solution reacted with the polyimide by reprecipitation or the like, a poor solvent for the polyimide for depositing the polyimide from the reaction solution reacted with the polyimide, if necessary, And a good solvent for polyimide for diluting the reaction solution by using a suitable solvent.
The solid concentration of the reaction solution (polyimide solution) when the poor solvent is added dropwise to precipitate polyimide is 0.1% by mass or more and 30% by mass from the viewpoint of yield and efficient removal of impurities. %, More preferably 1% by mass or more and 10% by mass or less.
In order to make the solid content concentration of the polyimide solution suitable for polyimide deposition, the polyimide solution may be appropriately diluted with a good polyimide solvent.
In addition, as a guide, a good solvent for polyimide can be appropriately selected from solvents having a polyimide solubility of 20 g / 100 g or more at 25 ° C. and used.
As a guide, the poor solvent for polyimide can be appropriately selected from solvents having a polyimide solubility of less than 20 g / 100 g at 25 ° C.

For example, to a reaction solution reacted with polyimide, for example, an organic solvent which is a good solvent for polyimide such as normal-butyl acetate is added and stirred until uniform to dilute the reaction solution, and then t-butanol, methanol Then, an alcohol-based organic solvent such as ethanol, isopropyl alcohol, 2-butanol, cyclohexanol, and t-amyl alcohol is gradually added to precipitate a polyimide, a white slurry is obtained, and the slurry is filtered to obtain a polyimide. As the alcohol-based organic solvent, a secondary or tertiary alcohol is preferably used, and more preferably a tertiary alcohol is used, from the viewpoint of excellent polyimide stability.
It is preferable to measure the amount of residual solvent in the polyimide obtained by reprecipitation as described above. The residual solvent amount of the polyimide can be measured in the same manner as in the above-mentioned method for measuring the residual solvent amount of the polyimide film except that polyimide is used instead of the polyimide film. When measuring the residual solvent amount of the polyimide (polyimide material), the polyimide (polyimide material) is dried at 100 ° C. to 120 ° C. using a vacuum dryer. The drying time may be appropriately adjusted according to the amount of the polyimide (polyimide material). For example, in the case of polyimide (polyimide material) having a solid content of 100 g, drying may be performed for about 3 hours, and if drying is insufficient, an additional drying time may be appropriately added for one hour. The drying of the polyimide (polyimide material) using a vacuum dryer can be performed as a guide until the mass change of the polyimide (polyimide material) before and after the drying becomes 0.1% by mass or less.

It is preferable that the polyimide obtained by reprecipitation as described above repeats a washing step using an organic solvent in order to further remove the residual solvent.
For example, a washing process of washing a polyimide obtained by reprecipitation and washing with a beaker containing an organic solvent for washing and then filtering the same is repeated, and dried at 100 ° C. to 120 ° C. using a vacuum drier to obtain a polyimide ( Polyimide material).
As the organic solvent for washing, it is highly compatible with the residual solvent contained in the polyimide obtained by reprecipitation, is a poor solvent for polyimide, and is dried at 100 ° C to 120 ° C using a vacuum dryer. The organic solvent is selected from organic solvents having a boiling point lower than the drying temperature of the vacuum dryer so that all can be volatilized.
For example, when the residual solvent is N, N-dimethylacetamide, N-methyl-2-pyrrolidone, or the like used when preparing a polyimide precursor, isopropyl alcohol, methanol, or the like is suitably used as the organic solvent for washing. As the organic solvent for washing, one or more kinds can be used.
The polyimide obtained after the washing step as described above, the residual solvent amount is measured, it is determined whether the value is equal to or less than the value specified in the present invention, if it exceeds the value specified in the present invention, further washing It is preferable to include a step of reducing the residual solvent amount of the used polyimide (polyimide material) to a value equal to or less than the value specified in the present invention by using the step.
In this way, the content of the organic solvent having a boiling point of less than 100 ° C. is 2000 ppm or less, and the content of the organic solvent having a boiling point of 100 ° C. or more is 100 ppm or less, which is used for preparing the polyimide resin composition. (Polyimide material) can be obtained.

The polyimide material used for preparing the polyimide resin composition is preferably a polyimide powder, and the average particle size of the polyimide powder is 50 μm to 1000 μm from the viewpoint of easy handling as a powder. It is more preferable that the thickness be 100 μm to 500 μm.
The average particle diameter of the polyimide material (polyimide powder) in the present invention is obtained by observing the polyimide material (polyimide powder) with an optical microscope (Digital Microscope VHX-5000 manufactured by KEYENCE) at a magnification of 100 times, Randomly extract 150 particles of polyimide material, measure the particle diameter of each of the extracted particles, and calculate the average value. When the particle shape of the polyimide material is not spherical, the major axis is measured.

In the step of preparing the polyimide resin composition, examples of the organic solvent used when redissolving the polyimide (polyimide material) purified from the reaction solution include ethylene glycol monoethyl ether, ethylene glycol monoethyl ether acetate, and ethylene glycol mono- Normal-butyl ether, ethylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, ortho-dichlorobenzene, xylene, cresol, chlorobenzene, ethyl acetate, isobutyl acetate, isopentyl acetate, normal-butyl acetate, normal-propyl acetate, normal acetate Pentyl, cyclohexanol, cyclohexanone, 1.4-dioxane, tetrachloroethylene, toluene, methyl isobutyl ketone, methyl cycle Hexanol, methyl cyclohexanone, methyl - n - butyl ketone, dichloromethane, dichloroethane, chloroform, tetrahydrofuran, and a mixed solvent thereof and the like.
In the polyimide resin coating film forming step described below, when coating is performed in an open environment, the organic solvent for re-dissolving the polyimide is normal-butyl acetate, ethyl acetate, and propylene because the amount of the residual solvent is easily reduced. It is preferably at least one selected from the group consisting of glycol monomethyl ether acetate.
In the polyimide resin coating film forming step described below, the organic solvent for re-dissolving the polyimide, especially from the point that it is easy to reduce the residual solvent amount at the time of film production, the organic solvent having a boiling point of less than 100 ° C, especially the boiling point is 70 ° C or less It is preferable to use the organic solvent of the above. When an organic solvent having a boiling point of less than 100 ° C., particularly an organic solvent having a boiling point of 70 ° C. or less, is used, the amount of the residual solvent is easily reduced even when the coating is performed in a closed system environment.
Among them, it is easy to reduce the amount of the residual solvent, and from the viewpoint of being advantageous in a film-forming step such as a drying step, at least one selected from the group consisting of dichloromethane, ethyl acetate, chloroform, tetrahydrofuran, normal-butyl acetate, and propylene glycol monomethyl ether acetate. One type can be preferably used. Among them, at least one selected from the group consisting of dichloromethane, chloroform, tetrahydrofuran, and ethyl acetate is preferable in that the amount of the residual solvent is easily reduced and the film formation step such as a drying step is advantageous. Can be preferably used.

The polyimide resin composition may contain an additive as needed. As the additive, the same additives as those described in the step of preparing the polyimide precursor resin composition in the first manufacturing method can be used.
In addition, in the second production method, the method of reducing the water content of the polyimide resin composition to 1000 ppm or less, and the method of dispersing the inorganic particles in an organic solvent include the polyimide precursor in the first production method. The same method as the method described in the resin composition preparation step can be used.

  Further, in the polyimide resin coating film forming step in the second manufacturing method, the support and the coating method are the same as those described in the polyimide precursor resin coating film forming step in the first manufacturing method. be able to.

The drying step in the polyimide resin coating film forming step of the second manufacturing method includes the drying step and the heating during the imidization step described in the polyimide precursor resin coating film forming step of the first manufacturing method. It can be performed in the same manner as the process.
That is, first, the solvent in the polyimide resin composition is dried on the support in the same manner as in the drying step of the polyimide precursor resin coating film forming step of the first manufacturing method, and then the polyimide resin coating film is supported. It is preferable to have a step of further drying after peeling from the body, from the viewpoint that the amount of the residual solvent in the polyimide film is made equal to or less than the value specified in the present invention and the bending resistance is improved.
The temperature at which the polyimide resin coating is further dried after peeling from the support does not need to be as high as the heating temperature for imidization in the first production method, and the type of the organic solvent and the residual solvent used at the time of forming the coating and The amount may be appropriately adjusted. Under normal pressure, the temperature is preferably in the range of 80 ° C to 250 ° C, more preferably in the range of 100 ° C to 220 ° C. Under reduced pressure, the temperature is preferably in the range of 10 ° C to 200 ° C, and more preferably in the range of 30 ° C to 160 ° C. The drying time may be appropriately adjusted depending on the amount of the organic solvent and the amount of the residual solvent used at the time of forming the coating film. The drying time is usually from 2 minutes to 60 minutes, preferably from 5 minutes to 40 minutes. Exceeding the upper limit is not preferable from the viewpoint of the production efficiency of the polyimide film. On the other hand, when the value is below the lower limit, the residual solvent may not be sufficiently reduced, and further, rapid drying of the solvent may affect the appearance and the like of the obtained polyimide film.
In the step of further drying after peeling from the support, it is preferable to fix and dry the end portion of the polyimide resin coating film after peeling from the support from the viewpoint of preventing shrinkage during heating. The method of fixing the end portion of the polyimide resin coating film after peeling from the support can be performed in the same manner as the above-mentioned polyimide precursor resin coating film.

  Further, the second manufacturing method may include a stretching step of stretching the polyimide resin coating film after the polyimide resin coating film forming step. The stretching step can be the same as the stretching step in the first manufacturing method.

  The second manufacturing method is preferable because the yellowness (YI value) of the polyimide film is easily reduced. According to the second manufacturing method, it is possible to suitably form a polyimide film in which the value obtained by dividing the yellowness calculated based on JIS K7373-2006 by the film thickness (μm) is 0.04 or less. is there.

10. Use of Polyimide Film The use of the polyimide film of the present invention is not particularly limited, and the polyimide film can be used as a base material, a surface material, or the like, in which a glass product such as a thin plate glass is conventionally used. The polyimide film of the present invention has improved bending resistance, has a sufficient surface hardness as a protective film, and has a reduced optical distortion, and among others, it is preferably used as a display member capable of dealing with a curved surface. it can.
The polyimide film of the present invention, specifically, for example, a thin and flexible organic EL display of a flexible type, a mobile terminal such as a smartphone or a wristwatch-type terminal, a display device inside an automobile, a flexible panel used for a wristwatch or the like, It can be suitably used as a substrate or surface material for a flexible display. In addition, the polyimide film of the present invention may be used for a member for an image display device such as a liquid crystal display device or an organic EL display device, a member for a touch panel, a flexible printed circuit board, a member for a solar cell panel such as a surface protective film or a substrate material, and an optical waveguide. And other semiconductor-related members.

III. Laminate The laminate of the present invention is a laminate having the above-described polyimide film of the present invention and a hard coat layer containing at least one polymer of a radically polymerizable compound and a cationically polymerizable compound.
Since the laminate of the present invention uses the polyimide film of the present invention described above, it is excellent in transparency and has improved bending resistance, and further has a hard coat layer, so that the surface hardness is further improved. Film or resin film.

In addition, the laminate of the present invention is preferable because the polyimide contained in the polyimide film contains a diamine residue having a silicon atom in the main chain, so that the adhesion between the polyimide film and the hard coat layer is excellent. . This is presumed to be due to excellent mixing between the specific polyimide film and the hard coat layer.
Further, in the laminate of the present invention, the polyimide contained in the polyimide film is preferable in that optical distortion is reduced because the polyimide contains a diamine residue having a silicon atom in the main chain. In this case, when the laminate of the present invention is used as a display member such as a display surface material or a base material, it is possible to suppress a decrease in display quality of the display.

1. Polyimide Film As the polyimide film used in the laminate of the present invention, the above-described polyimide film of the present invention can be used, and a description thereof will be omitted.

2. Hard coat layer The hard coat layer used in the laminate of the present invention contains at least one polymer of a radically polymerizable compound and a cationically polymerizable compound.

(1) Radical polymerizable compound A radical polymerizable compound is a compound having a radical polymerizable group. The radical polymerizable group of the radical polymerizable compound may be any functional group capable of causing a radical polymerization reaction, and is not particularly limited. Examples thereof include a group including a carbon-carbon unsaturated double bond. Specific examples include a vinyl group and a (meth) acryloyl group. When the radically polymerizable compound has two or more radically polymerizable groups, these radically polymerizable groups may be the same or different.

The number of radically polymerizable groups in one molecule of the radically polymerizable compound is preferably two or more, and more preferably three or more, from the viewpoint of improving the hardness of the hard coat layer.
As the radical polymerizable compound, from the viewpoint of high reactivity, a compound having a (meth) acryloyl group is preferable, and a polyfunctional acrylate monomer having 2 to 6 (meth) acryloyl groups in one molecule is preferably used. Oligomers having several (meth) acryloyl groups in a molecule called a compound or urethane (meth) acrylate, polyester (meth) acrylate or epoxy (meth) acrylate having a molecular weight of several hundred to several thousand are preferable. Can be used.
In addition, in this specification, (meth) acryloyl represents each of acryloyl and methacryloyl, and (meth) acrylate represents each of acrylate and methacrylate.

  As the radical polymerizable compound, specifically, for example, a vinyl compound such as divinylbenzene; ethylene glycol di (meth) acrylate, bisphenol A epoxy di (meth) acrylate, 9,9-bis [4- (2- ( (Meth) acryloyloxyethoxy) phenyl] fluorene, alkylene oxide-modified bisphenol A di (meth) acrylate (eg, ethoxylated (ethylene oxide-modified) bisphenol A di (meth) acrylate, etc.), trimethylolpropane tri (meth) acrylate, trimethyl Methylolethane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol tri (meth) acrylate, dipentaeryth Polyol polyacrylates such as tall tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, bisphenol A diglycidyl ether diacrylate, hexanediol diglycidyl ether diacrylate and the like Examples include epoxy acrylates, urethane acrylates obtained by the reaction of polyisocyanates with hydroxyl-containing acrylates such as hydroxyethyl acrylate, and the like.

(2) Cationic polymerizable compound The cationic polymerizable compound is a compound having a cationic polymerizable group. The cationically polymerizable group contained in the cationically polymerizable compound is not particularly limited as long as it is a functional group capable of causing a cationic polymerization reaction, and examples thereof include an epoxy group, an oxetanyl group, and a vinyl ether group. When the cationically polymerizable compound has two or more cationically polymerizable groups, these cationically polymerizable groups may be the same or different.

The number of the cationically polymerizable groups in one molecule of the cationically polymerizable compound is preferably two or more, and more preferably three or more from the viewpoint of improving the hardness of the hard coat layer.
Further, as the cationic polymerizable compound, among others, a compound having at least one of an epoxy group and an oxetanyl group as a cationic polymerizable group is preferable, and from the viewpoint of adhesion and light transmittance and surface hardness, an epoxy group and Compounds having two or more oxetanyl groups in one molecule are more preferred. Cyclic ether groups such as an epoxy group and an oxetanyl group are preferred in that shrinkage due to the polymerization reaction is small. Compounds having an epoxy group among the cyclic ether groups are easily available in compounds having various structures, do not adversely affect the durability of the obtained hard coat layer, and are easily controlled in compatibility with the radical polymerizable compound. There is an advantage that. The oxetanyl group among the cyclic ether groups has a higher degree of polymerization than the epoxy group, has low toxicity, and has a cation in the coating film when the obtained hard coat layer is combined with a compound having an epoxy group. There are advantages such as increasing the rate of network formation obtained from the polymerizable compound and forming an independent network without leaving unreacted monomer in the film even in a region where the radical polymerizable compound is mixed.

  Examples of the cationically polymerizable compound having an epoxy group include, for example, a polyglycidyl ether of a polyhydric alcohol having an alicyclic ring, or a cyclohexene ring or a cyclopentene ring-containing compound, with an appropriate oxidizing agent such as hydrogen peroxide or peracid. Alicyclic epoxy resin obtained by epoxidation; polyglycidyl ether of aliphatic polyhydric alcohol or its alkylene oxide adduct, polyglycidyl ester of aliphatic long-chain polybasic acid, homopolymer of glycidyl (meth) acrylate, Aliphatic epoxy resins such as copolymers; bisphenols such as bisphenol A, bisphenol F and hydrogenated bisphenol A, or their derivatives such as alkylene oxide adducts and caprolactone adducts, and glycidyl ether produced by reaction with epichlorohydrin Ether, and novolac epoxy resins such as a and glycidyl ether type epoxy resins derived from bisphenols are exemplified.

  Examples of the alicyclic epoxy resin include 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate (UVR-6105, UVR-6107, UVR-6110) and bis-3,4-epoxycyclohexylmethyl adipate. (UVR-6128) (both in parentheses are trade names and manufactured by Dow Chemical).

  Examples of the glycidyl ether type epoxy resin include sorbitol polyglycidyl ether (Denacol EX-611, Denacol EX-612, Denacol EX-614, Denacol EX-614B, Denacol EX-622), polyglycerol polyglycidyl ether (Denacol EX) -512, denacol EX-521), pentaerythritol polyglycidyl ether (denacol EX-411), diglycerol polyglycidyl ether (denacol EX-421), glycerol polyglycidyl ether (denacol EX-313, denacol EX-314), Trimethylolpropane polyglycidyl ether (Denacol EX-321), resortinol diglycidyl ether (Denacol EX-201), neopentyl Recohol diglycidyl ether (Denacol EX- 211), 1,6 hexanediol diglycidyl ether (Denacol EX-212), hydrodibisphenol A diglycidyl ether (Denacol EX-252), ethylene glycol diglycidyl ether (Denacol EX-810) , Denacol EX-811), polyethylene glycol diglycidyl ether (Denacol EX-850, Denacol EX-851, Denacol EX-821), propylene glycol glycidyl ether (Denacol EX-911), polypropylene glycol glycidyl ether (Denacol EX-941, Denacol EX-920), allyl glycidyl ether (denacol EX-111), 2-ethylhexyl glycidyl ether (denaco EX-121), phenyl glycidyl ether (Denacol EX-141), phenol glycidyl ether (Denacol EX-145), butylphenyl glycidyl ether (Denacol EX-146), diglycidyl phthalate (Denacol EX-721), hydroquinone diglycidyl ether (Denacol EX-203), diglycidyl terephthalate (denacol EX-711), glycidyl phthalimide (denacol EX-731), dibromophenyl glycidyl ether (denacol EX-147), dibromoneopentyl glycol diglycidyl ether (denacol EX-221) (The above is the product name in parentheses, manufactured by Nagase ChemteX.).

  Other commercially available epoxy resins include trade names Epicoat 825, Epicoat 827, Epicoat 828, Epicoat 828EL, Epicoat 828XA, Epicoat 834, Epicoat 801 and Epicoat 801P, Epicoat 802, Epicoat 815, Epicoat 815XA, Epicoat 816A, Epicoat 819, Epicoat 834X90, Epicoat 1001B80, Epicoat 1001X70, Epicoat 1001X75, Epicoat 1001T75, Epicoat 806, Epicoat 806P, Epicoat 807, Epicoat 152, Epicoat 154, Epicoat 871, Epicoat 191P, Epicoat YX310, Epicoat DX255, Epicoat YX8000 Etc. (More than product name, Bread epoxy resin) and the like.

  Examples of the cationically polymerizable compound having an oxetanyl group include 3-ethyl-3-hydroxymethyloxetane (OXT-101) and 1,4-bis-3-ethyloxetane-3-ylmethoxymethylbenzene (OXT-121). , Bis-1-ethyl-3-oxetanyl methyl ether (OXT-221), 3-ethyl-3--2-ethylhexyloxymethyl oxetane (OXT-212), 3-ethyl-3-phenoxymethyl oxetane (OXT- 211) (both in parentheses are trade names of Toagosei Co., Ltd.) and trade names of etanacol EHO, etanacol OXBP, etanacol OXTP, and etanacol OXMA (trade names, manufactured by Ube Industries).

(3) Polymerization initiator At least one polymer of the radically polymerizable compound and the cationically polymerizable compound contained in the hard coat layer used in the present invention is, for example, one of the radically polymerizable compound and the cationically polymerizable compound. It can be obtained by adding a polymerization initiator to at least one kind as necessary and conducting a polymerization reaction by a known method.

  As the polymerization initiator, a radical polymerization initiator, a cationic polymerization initiator, a radical and cationic polymerization initiator, or the like can be appropriately selected and used. These polymerization initiators are decomposed by at least one of light irradiation and heating, and generate radicals or cations to promote radical polymerization and cationic polymerization.

  The radical polymerization initiator only needs to be capable of releasing a substance that initiates radical polymerization by at least one of light irradiation and heating. For example, examples of the photoradical polymerization initiator include imidazole derivatives, bisimidazole derivatives, N-arylglycine derivatives, organic azide compounds, titanocenes, aluminate complexes, organic peroxides, N-alkoxypyridinium salts, and thioxanthone derivatives. More specifically, 1,3-di (tert-butyldioxycarbonyl) benzophenone, 3,3 ′, 4,4′-tetrakis (tert-butyldioxycarbonyl) benzophenone, 3-phenyl-5- Isoxazolone, 2-mercaptobenzimidazole, bis (2,4,5-triphenyl) imidazole, 2,2-dimethoxy-1,2-diphenylethan-1-one (trade name Irgacure 651, Ciba Japan Co., Ltd.) Manufactured), 1-hydroxy-cyclohexyl-phenyl Ketone (trade name Irgacure 184, manufactured by Ciba Japan KK), 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butan-1-one (trade name Irgacure 369, Ciba Japan ( Co., Ltd.), bis (η5-2,4-cyclopentadien-1-yl) -bis (2,6-difluoro-3- (1H-pyrrol-1-yl) -phenyl) titanium) (trade name Irgacure 784) And Ciba Japan K.K.) and the like, but are not limited thereto.

  In addition to the above, commercially available products can be used. Specifically, Irgacure 907, Irgacure 379, Irgacure 819, Irgacure 127, Irgacure 500, Irgacure 754, Irgacure 250, Irgacure 1800, and Irgacure 1870 manufactured by Ciba Japan KK , Irgacure OXE01, DAROCUR TPO, DAROCUR1173, Japan Siber Hegner Co., Ltd. of SpeedcureMBB, SpeedcurePBZ, SpeedcureITX, SpeedcureCTX, SpeedcureEDB, Esacure ONE, Esacure KIP150, Esacure KTO46, manufactured by Nippon Kayaku Co., of (stock) KAYACURE DETX-S, KAYACURE CTX , KAYACURE BMS, K YACURE DMBI, and the like.

The cationic polymerization initiator only needs to be capable of releasing a substance that initiates cationic polymerization by at least one of light irradiation and heating. Examples of the cationic polymerization initiator include sulfonic acid esters, imidosulfonates, dialkyl-4-hydroxysulfonium salts, arylsulfonic acid-p-nitrobenzyl esters, silanol-aluminum complexes, (η ⁶ -benzene) (η ⁵ -cyclopentadiene) Enyl) iron (II) and the like, and more specifically, include, but are not limited to, benzoin tosylate, 2,5-dinitrobenzyl tosylate, N-tosiphthalimide, and the like.

  As the radical polymerization initiator, those used as the cationic polymerization initiator include aromatic iodonium salts, aromatic sulfonium salts, aromatic diazonium salts, aromatic phosphonium salts, triazine compounds, iron arene complexes, and the like. More specifically, chlorides, bromides, fluorinated salts, hexafluorophosphate salts, hexafluorophosphate salts of iodonium such as diphenyliodonium, ditolyliodonium, bis (p-tert-butylphenyl) iodonium, bis (p-chlorophenyl) iodonium, etc. Iodonium salts such as antimonate salts; triphenylsulfonium; 4-tert-butyltriphenylsulfonium; tris (4-methylphenyl) sulfonium; Sulfonium salts such as olophosphate salts and hexafluoroantimonate salts, 2,4,6-tris (trichloromethyl) -1,3,5-triazine, 2-phenyl-4,6-bis (trichloromethyl) -1, Examples include 2,4,6-substituted-1,3,5 triazine compounds such as 3,5-triazine and 2-methyl-4,6-bis (trichloromethyl) -1,3,5-triazine. It is not limited to these.

(4) Additives In addition to the polymer, the hard coat layer used in the present invention may optionally contain an antistatic agent, an antiglare agent, an antifouling agent, inorganic or organic fine particles for improving hardness, Additives such as a leveling agent and various sensitizers may be contained.

  In addition, at least one kind of a polymerizable compound of a radical polymerizable compound and a cationic polymerizable compound contained in the hard coat layer used in the present invention is obtained by a Fourier transform infrared spectrophotometer (FTIR), a pyrolysis gas chromatograph (GC) -MS) or a decomposition product of a polymer can be analyzed using a combination of high-performance liquid chromatography, gas chromatography / mass spectrometer, NMR, elemental analysis, XPS / ESCA, TOF-SIMS, and the like.

3. The laminate of the present invention is not particularly limited as long as it has the polyimide film and the hard coat layer, and the hard coat layer is laminated on one surface side of the polyimide film. And the hard coat layer may be laminated on both sides of the polyimide film. In addition, the laminate of the present invention, in a range that does not impair the effects of the present invention, in addition to the polyimide film and the hard coat layer, for example, to improve the adhesion between the polyimide film and the hard coat layer It may have another layer such as a primer layer, or may have the polyimide film and the hard coat layer laminated via another layer such as a primer layer. Further, the laminate of the present invention may be one in which the polyimide film and the hard coat layer are located adjacent to each other. Further, the laminate of the present invention may further have an impact resistant layer, a fingerprint adhesion preventing layer, an adhesive or adhesive layer, and the like.

The total thickness of the laminate of the present invention may be appropriately selected depending on the application, but is preferably 10 μm or more, and more preferably 40 μm or more from the viewpoint of strength. On the other hand, from the viewpoint of bending resistance, the thickness is preferably 300 μm or less, and more preferably 250 μm or less.
In the laminate of the present invention, the thickness of each hard coat layer may be appropriately selected depending on the application, but is preferably 2 μm or more and 80 μm or less, more preferably 3 μm or more and 50 μm or less. Further, from the viewpoint of curling prevention, a hard coat layer may be formed on both sides of the polyimide film.

4. Characteristics of Laminate In the laminate of the present invention, the pencil hardness of the surface on the hard coat layer side is preferably H or more, more preferably 2H or more, even more preferably 3H or more.
The pencil hardness of the laminate of the present invention can be measured in the same manner as in the method for measuring the pencil hardness of the polyimide film, except that the load is set to 9.8 N.

The laminate of the present invention preferably has a total light transmittance of 85% or more, more preferably 88% or more, and still more preferably 90% or more, measured in accordance with JIS K7361-1. Is preferred. Since the transmittance is high as described above, the transparency is improved and the glass can be used as a substitute material for glass.
The total light transmittance of the laminate of the present invention can be measured in the same manner as the total light transmittance of the polyimide film measured according to JIS K7361-1.

The laminate of the present invention has a yellowness (YI value) calculated in accordance with JIS K7373-2006 of preferably 20 or less, more preferably 15 or less, and more preferably 10 or less. More preferably, it is particularly preferably 5 or less.
In addition, since the laminate of the present invention suppresses coloring of yellowish tint, improves light transmittance, and can be suitably used as a glass substitute material, the yellowish color calculated based on JIS K7373-2006 is used. The value obtained by dividing the degree (YI value) by the film thickness (μm) (YI value / film thickness (μm)) is preferably 0.10 or less, more preferably 0.04 or less, and 0.03 or less. It is even more preferred that:
The yellowness (YI value) of the laminate of the present invention can be measured in the same manner as the yellowness (YI value) calculated based on JIS K7373-2006 of the polyimide film.

5. Use of Laminate The use of the laminate of the present invention is not particularly limited, and for example, can be used for the same uses as the above-mentioned use of the polyimide film of the present invention.

6. Production method of laminate The production method of the laminate of the present invention, for example,
Forming a coating film of a composition for forming a hard coat layer containing at least one of a radically polymerizable compound and a cationically polymerizable compound on at least one surface of the polyimide film of the present invention;
And a step of curing the coating film.

The composition for forming a hard coat layer contains at least one of a radically polymerizable compound and a cationically polymerizable compound, and may further contain a polymerization initiator, a solvent, an additive, and the like, if necessary.
Here, the radical polymerizable compound, the cationic polymerizable compound, the polymerization initiator and the additive contained in the hard coat layer forming composition may be the same as those described in the hard coat layer. The solvent can be appropriately selected and used from known solvents.

As a method of forming a coating film of the composition for forming a hard coat layer on at least one surface of a polyimide film, for example, the composition for forming a hard coat layer on at least one surface of the polyimide film may be a known method. A method of applying by a coating means is exemplified.
The application unit is not particularly limited as long as it is a method capable of applying a desired film thickness, and examples thereof include the same units as those for applying the polyimide precursor resin composition to a support.

  The coating film of the curable resin composition for a hard coat layer is dried as necessary to remove the solvent. Examples of the drying method include a method of drying under reduced pressure or drying by heating, and a method of combining these drying methods. When drying at normal pressure, it is preferable to dry at 30 ° C. or higher and 110 ° C. or lower.

  The curable resin composition for the hard coat layer is applied and, if necessary, for the dried coating film, depending on the polymerizable groups of the radically polymerizable compound and the cationically polymerizable compound contained in the curable resin composition. By curing the coating by at least one of light irradiation and heating, a hard coat layer containing at least one polymer of a radical polymerizable compound and a cationic polymerizable compound is formed on at least one surface of the polyimide film. Can be formed.

Ultraviolet rays, visible light, electron beams, ionizing radiation, and the like are mainly used for light irradiation. In the case of ultraviolet curing, ultraviolet rays emitted from light rays such as an ultrahigh-pressure mercury lamp, a high-pressure mercury lamp, a low-pressure mercury lamp, a carbon arc, a xenon arc, and a metal halide lamp are used. The irradiation amount of the energy ray source is about 50 to 5000 mJ / cm ² as an integrated exposure amount at an ultraviolet wavelength of 365 nm.
When heating, the treatment is usually performed at a temperature of 40 ° C. or more and 120 ° C. or less. Alternatively, the reaction may be carried out by leaving at room temperature (25 ° C.) for 24 hours or more.

IV. Display member The display member of the present invention includes the above-described polyimide film of the present invention or the laminate of the present invention.
Examples of the display member of the present invention include a display surface material and a display substrate.
The display member of the present invention may be the above-described polyimide film of the present invention or the laminate of the present invention.

  The display member of the present invention is used, for example, as a display surface material so as to be located on the surface of various displays. The display member of the present invention is excellent in transparency, improved in bending resistance, and has a sufficient surface hardness as a protective film, like the above-described polyimide film of the present invention and the laminate of the present invention. Can be particularly preferably used.

  The display member of the present invention can be used for various known displays, and is not particularly limited. For example, it can be used for the display described in the application of the polyimide film of the present invention.

  When the display member of the present invention is the laminate of the present invention, the surface that becomes the outermost surface after disposing the laminate on the surface of the display may be the surface on the polyimide film side, or may be hard. It may be the surface on the coat layer side. Above all, it is preferable to arrange the display member of the present invention such that the surface on the hard coat layer side is a more front side surface. Further, the display member of the present invention may have a fingerprint adhesion preventing layer on the outermost surface.

  Further, the method for arranging the display member of the present invention on the surface of the display is not particularly limited, and examples thereof include a method via an adhesive layer. As the adhesive layer, a conventionally known adhesive layer that can be used for bonding a display member can be used.

V. Touch panel member The touch panel member of the present invention includes the polyimide film of the present invention described above or the laminate of the present invention described above,
A transparent electrode composed of a plurality of conductive portions, disposed on one surface side of the polyimide film or the laminate,
And a plurality of extraction lines electrically connected to at least one of the ends of the conductive portion.

Since the touch panel member of the present invention is provided with the above-described polyimide film or laminate of the present invention and has excellent bending resistance, it can be particularly suitably used for a flexible display and has optical characteristics. Excellent.
The laminate of the present invention used for the touch panel member of the present invention has a hard coat layer containing at least one polymer of a radically polymerizable compound and a cationically polymerizable compound adjacent to both surfaces of a polyimide film. Preferably, there is.
Further, the touch panel member of the present invention is not particularly limited, but it is preferable that the transparent electrode is laminated in contact with one surface side of the laminate.
The touch panel member of the present invention can be arranged and used, for example, so as to be located on the surface of various displays. In addition, the touch panel member of the present invention and the polyimide film or laminate of the present invention as a surface material may be arranged and used in this order on the surface of various displays.

Hereinafter, the touch panel member of the present invention will be described using an example using the above-described laminate of the present invention. Instead of the above-described laminate of the present invention, the above-described polyimide film of the present invention can be used in the same manner. .
FIG. 2 is a schematic plan view of one surface of an example of the touch panel member of the present invention, FIG. 3 is a schematic plan view of the other surface of the touch panel member shown in FIG. 2, and FIG. FIG. 4 is a sectional view of the touch panel member taken along line AA ′ of FIG. 3. The touch panel member 20 shown in FIGS. 2, 3 and 4 includes a laminate 10 of the present invention, the first transparent electrode 4 arranged in contact with one surface of the laminate 10, and the other of the laminate 10. And a second transparent electrode 5 disposed in contact with the surface of the second transparent electrode 5. In the first transparent electrode 4, a plurality of first conductive portions 41, which are strip-shaped electrode pieces extending so as to extend in the x-axis direction, are arranged at predetermined intervals. The first lead wire 7 electrically connected to the first conductive portion 41 is connected to the first conductive portion 41 at one of the ends in the longitudinal direction. A first terminal 71 for electrically connecting to an external circuit may be provided at an end of the first extraction line 7 extending to the edge 21 of the laminate 10. In general, the first conductive portion 41 and the first extraction line 7 are connected in an inactive area 23 located outside the active area 22 that can be visually recognized by a user of the touch panel.
The connection between the first conductive portion 41 and the first extraction line 7 can adopt, for example, a connection structure in which the connection portion 24 is interposed as shown in FIG. Specifically, the connection portion 24 can be formed by extending a layer of a conductive material from a longitudinal end of the first conductive portion 41 to a predetermined position in the inactive area 23. Furthermore, a connection structure between the first conductive portion 41 and the first extraction line 7 can be formed by overlapping at least a part of the first extraction line 7 on the connection portion 24.
The connection between the first conductive portion 41 and the first extraction line 7 is not limited to the structure forming the connection portion 24 as shown in FIG. For example, although not shown, the longitudinal end of the first conductive portion 41 is extended to the inactive area 23, and the first conductive portion 41 extended to the inactive area 23 in the inactive area 23. May be electrically connected to each other by riding the first wire 7 on the end of the wire.
Note that FIG. 2 shows an embodiment in which one of the longitudinal ends of the first conductive portion 41 is connected to the first extraction line 7. However, in the present invention, one first conductive portion 41 is connected to the first conductive portion 41. The first extraction line 7 may be electrically connected to both ends of the portion 41 in the longitudinal direction.

As shown in FIG. 3, the touch panel member 20 includes the second transparent electrode 5 disposed in contact with the other surface of the multilayer body 10. In the second transparent electrode 5, the second conductive portions 51, which are a plurality of strip-shaped electrode pieces extending so as to extend in the y-axis direction, are arranged at predetermined intervals in the x-axis direction. I have.
At one end of the second conductive portion 51 in the longitudinal direction, a second extraction line 8 that is electrically connected to the second conductive portion 51 is connected.
The second extraction line 8 extends from the edge of the stacked body 10 to a position on the edge 21 where the above-described first extraction line 7 extends so as not to overlap the first terminal 71. .
A second terminal 81 for electrically connecting to an external circuit may be provided at an end of the second extraction line 8 extending to the edge 21 of the laminate 10.
As for the electrical connection between the second conductive portion 51 and the second extraction line 8, the same form as the electrical connection between the first extraction line 7 and the first conductive portion 41 can be applied. .

  The pattern in which the first extraction line 7 is a long wiring and the second extraction line 8 is a short wiring as shown in FIGS. 2 and 3 is only an embodiment of the touch panel member of the present invention, It is also possible to use a pattern in which the first extraction line 7 is a short wiring and the second extraction line 8 is a long wiring. Further, the extension direction of the first extraction line 7 and the extension direction of the second extraction line 8 are not limited to the directions shown in FIGS. 2 and 3 and can be arbitrarily designed.

The conductive portion included in the touch panel member of the present invention can be appropriately selected from those that constitute the transparent electrode in the touch panel member, and the pattern of the conductive portion is not limited to those shown in FIGS. 2 and 3. For example, a pattern of a transparent electrode capable of detecting a change in electric capacitance due to contact or close contact with a finger or the like can be appropriately selected and applied by a capacitance method.
The material of the conductive portion is preferably a light transmissive material, for example, an indium oxide-based transparent electrode material containing indium tin oxide (ITO), indium oxide, indium zinc oxide (IZO), or the like as a main component. , Tin oxide (SnO ₂ ), zinc oxide (ZnO), etc., and a transparent conductive film, and a conductive polymer compound such as polyaniline and polyacetylene, etc., but are not limited thereto. Further, the first conductive portion 41 and the second conductive portion 51 may be formed using the same kind of conductive material, or may be formed using different kinds of materials. In particular, it is preferable to form the first conductive portion 41 and the second conductive portion 51 using the same type of conductive material from the viewpoint that the occurrence of warpage and distortion of the touch panel member can be more effectively suppressed.
The thickness of the conductive portion is not particularly limited. For example, when the conductive portion is formed by a photolithography technique, the thickness can be generally about 10 nm to 500 nm.

The conductive material constituting the lead wire included in the touch panel member of the present invention may or may not have light transmittance. In general, the lead wire can be formed using a metal material having high conductivity, such as silver or copper. Specific examples include a metal simple substance, a composite of a metal, a composite of a metal and a metal compound, and a metal alloy. Examples of the simple metal include simple silver, copper, gold, chromium, platinum, and aluminum. Examples of the metal composite include MAM (three-layer structure of molybdenum, aluminum, and molybdenum). Examples of the composite of a metal and a metal compound include a laminate of chromium oxide and chromium. Silver alloys and copper alloys are commonly used as metal alloys. Further, examples of the metal alloy include APC (alloy of silver, palladium, and copper) and the like. Further, in the lead-out line, a resin component may be appropriately mixed with the above-described metal material.
In the touch panel member of the present invention, the terminal provided at the end of the wire may be formed using, for example, the same material as the wire.
The thickness and width of the extraction line are not particularly limited. For example, when the extraction line is formed by a photolithography method, the thickness is generally formed to about 10 nm to 1000 nm, and the width is 5 μm to It is formed to about 200 μm. On the other hand, when forming the extraction line by printing such as screen printing, the thickness is generally formed to about 5 μm to 20 μm, and the width is formed to about 20 μm to 300 μm.

The touch panel member of the present invention is not limited to the forms shown in FIGS. 2 to 4, and is configured by, for example, laminating a first transparent electrode and a second transparent electrode on separate laminates. May be used.
5 and 6 are schematic plan views each showing an example of a conductive member provided with the laminate of the present invention. The first conductive member 201 shown in FIG. 5 includes the laminate 10 of the present invention, and the first transparent electrode 4 arranged in contact with one surface of the laminate 10, The transparent electrode 4 has a plurality of first conductive portions 41. The second conductive member 202 shown in FIG. 6 includes the laminate 10 ′ of the present invention and the second transparent electrode 5 arranged in contact with one surface of the laminate 10 ′. The two transparent electrodes 5 have a plurality of second conductive portions 51.
FIG. 7 is a schematic cross-sectional view illustrating another example of the touch panel member of the present invention. The touch panel member 20 ′ illustrated in FIG. 7 includes a first conductive member 201 illustrated in FIG. And a conductive member 202. In the touch panel member 20 ′, the surface of the first conductive member 201 that does not have the first transparent electrode 4 and the surface of the second conductive member 202 that has the transparent electrode 5 are disposed via the adhesive layer 6. Laminated. In the present invention, for example, an adhesive layer for bonding the laminate of the present invention to the touch panel member of the present invention, an adhesive layer for bonding the touch panel members of the present invention to each other, the touch panel member of the present invention and a display device As an adhesive layer for adhering to the like, a conventionally known adhesive layer used for an optical member can be appropriately selected and used. In the conductive member used in the touch panel member of the present invention, the configuration and material of the transparent electrode, the lead wire and the terminal may be the same as those of the transparent electrode, the lead wire and the terminal used in the touch panel member of the present invention described above. it can.

VI. Liquid crystal display device The liquid crystal display device of the present invention includes the above-described polyimide film of the present invention or the above-described laminate of the present invention, and a liquid crystal between a counter substrate disposed on one surface side of the polyimide film or the laminate. And a liquid crystal display portion having a layer.

Since the liquid crystal display device of the present invention includes the above-described polyimide film of the present invention or the above-described laminate of the present invention, the liquid crystal display device has excellent bending resistance, and can be particularly suitably used for a flexible display, and has an optical characteristic. Excellent.
The laminate of the present invention used in the liquid crystal display device of the present invention has a hard coat layer containing at least one polymer of a radically polymerizable compound and a cationically polymerizable compound adjacent to both sides of a polyimide film. It is preferable that
Further, the liquid crystal display device of the present invention may include the touch panel member of the present invention described above.
The counter substrate of the liquid crystal display device of the present invention may include the polyimide film or the laminate of the present invention.

Hereinafter, the liquid crystal display device of the present invention will be described using an example using the above-described laminate of the present invention. Instead of the above-described laminate of the present invention, the above-described polyimide film of the present invention may be similarly used. it can.
FIG. 8 is a schematic sectional view showing an example of the liquid crystal display device of the present invention. The liquid crystal display device 100 shown in FIG. 8 includes the laminate 10 of the present invention and the first transparent electrode 4 on one surface of the laminate 10 ′ of the present invention, and the second transparent electrode 5 on the other surface. , And a liquid crystal display unit 30. In the liquid crystal display device 100, the laminate 10 is used as a surface material, and the laminate 10 and the touch panel member 20 are bonded to each other via the adhesive layer 6.

The liquid crystal display portion used in the liquid crystal display device of the present invention has a liquid crystal layer formed between substrates disposed opposite to each other, and may employ a configuration used in a conventionally known liquid crystal display device. it can.
The driving method of the liquid crystal display device of the present invention is not particularly limited, and a driving method generally used for a liquid crystal display device can be employed. For example, a TN method, an IPS method, an OCB method, and an MVA method And the like.
The counter substrate used in the liquid crystal display device of the present invention can be appropriately selected and used depending on the driving method of the liquid crystal display device and the like, and a substrate provided with the polyimide film or the laminate of the present invention may be used.
As the liquid crystal constituting the liquid crystal layer, various liquid crystals having different dielectric anisotropy and a mixture thereof can be used according to the driving method of the liquid crystal display device of the present invention and the like.
As a method for forming the liquid crystal layer, a method generally used as a method for manufacturing a liquid crystal cell can be used, and examples thereof include a vacuum injection method and a liquid crystal dropping method. After forming the liquid crystal layer by the above method, the sealed liquid crystal can be oriented by gradually cooling the liquid crystal cell to room temperature.
In the liquid crystal display device of the present invention, a colored layer of a plurality of colors and a light-shielding portion for defining pixels may be further provided between the opposed substrates. Further, the liquid crystal display section may have a backlight section having a light emitting element and a phosphor at a position on the opposite side to the side where the touch panel member is located outside the substrate disposed opposite to the liquid crystal display section. Further, a polarizing plate may be provided on each of the outer surfaces of the substrates arranged to face each other.

  FIG. 9 is a schematic sectional view showing another example of the liquid crystal display device of the present invention. The liquid crystal display device 200 shown in FIG. 9 includes a laminate 10 of the present invention, a first conductive member 201 including the first transparent electrode 4 on one surface of the laminate 10 ′ of the present invention, The liquid crystal display unit 30 includes a touch panel member 20 ′ having a second conductive member 202 having the second transparent electrode 5 on one surface of the laminate 10 ″, and a liquid crystal display unit 30. And the first conductive member 201, and the first conductive member 201 and the second conductive member 202 are respectively bonded via the adhesive layer 6. The configuration of the touch panel member 20 'is, for example, The configuration can be the same as the configuration of the touch panel member 20 'shown in Fig. 7. As the conductive member used for the liquid crystal display device of the present invention, the same conductive member used for the touch panel member of the present invention can be used. Can be used Kill.

VII. Organic electroluminescent display device The organic electroluminescent display device of the present invention includes the polyimide film of the present invention described above or the laminate of the present invention described above, and the polyimide film or the laminate of the present invention is disposed on one surface side of the polyimide film or the laminate. And an organic electroluminescence display section having an organic electroluminescence layer between the substrates.

Since the organic electroluminescent display device of the present invention includes the polyimide film of the present invention described above or the laminate of the present invention described above, it is excellent in bending resistance, so that it is particularly suitably used for a flexible display. It can be used and has excellent optical properties.
The laminate of the present invention used in the organic electroluminescent display device of the present invention includes a hard coat layer containing at least one polymer of a radically polymerizable compound and a cationically polymerizable compound adjacent to both surfaces of a polyimide film. It is preferable to have one.
Further, the organic electroluminescent display device of the present invention may include the above-mentioned touch panel member of the present invention.
Further, the opposing substrate of the organic electroluminescent display device of the present invention may include the polyimide film or the laminate of the present invention.

  FIG. 10 is a schematic sectional view showing an example of the organic electroluminescent display device of the present invention. The organic electroluminescence display device 300 shown in FIG. 10 includes the laminate 10 of the present invention and the first transparent electrode 4 on one surface of the laminate 10 ′ of the present invention, and the second transparent electrode 4 on the other surface. It has a touch panel member 20 having the electrode 5 and an organic electroluminescence display section 40. In the organic electroluminescence display device 300, the laminate 10 is used as a surface material, and the laminate 10 and the touch panel member 20 are bonded together via the adhesive layer 6.

The organic electroluminescence display unit (organic EL display unit) used in the organic electroluminescence display device (organic EL display device) of the present invention is an organic electroluminescence layer (organic EL layer) formed between opposed substrates. And a configuration used in a conventionally known organic EL display device can be adopted.
The organic EL display unit further includes a support substrate, an organic EL element including an organic EL layer, an anode layer and a cathode layer sandwiching the organic EL layer, and a sealing base material for sealing the organic EL element. May be. The organic EL layer may have at least an organic EL light emitting layer. For example, from the anode layer side, a hole injection layer, a hole transport layer, an organic EL light emitting layer, an electron transport layer, and an electron injection A layer having a structure in which layers are stacked in this order can be used.
The organic EL display device of the present invention can be applied to, for example, a passive drive type organic EL display and an active drive type organic EL display. The opposing substrate used in the organic EL display device of the present invention can be appropriately selected and used according to the driving method of the organic EL display device, and a substrate provided with the laminate of the present invention may be used.

  FIG. 11 is a schematic sectional view showing another example of the organic electroluminescent display device of the present invention. An organic electroluminescence display device 400 shown in FIG. 11 includes a laminate 10 of the present invention, a first conductive member 201 including the first transparent electrode 4 on one surface of the laminate 10 ′ of the present invention, It has a touch panel member 20 ′ having a second conductive member 202 provided with the second transparent electrode 5 on one surface of the laminate 10 ″ of the present invention, and an organic electroluminescence display section 40. An organic electroluminescence display device In 400, the laminate 10 and the first conductive member 201, and the first conductive member 201 and the second conductive member 202 are bonded to each other via the adhesive layer 6. The touch panel member 20 ' Can be the same as, for example, the configuration of the touch panel member 20 ′ shown in Fig. 7. The configuration is used for the organic electroluminescence display device of the present invention. As the conductive member, it can be the same as the conductive member for use in a touch panel member of the present invention.

[Evaluation method]
Hereinafter, unless otherwise specified, measurement or evaluation was performed at 25 ° C.
A test piece of the film was cut out from near the center of the film. A total of five film thicknesses at the four corners and the center of the cut film were measured by the above-described film thickness measurement method. A test piece was used.

<Weight average molecular weight of polyimide precursor>
The weight average molecular weight of the polyimide precursor is determined by developing the polyimide precursor into a 0.5% by weight N-methylpyrrolidone (NMP) solution, filtering the solution through a syringe filter (pore size: 0.45 μm), and developing the solution. As a solvent, a 10 mmol% LiBr-NMP solution having a water content of 500 ppm or less was used, a GPC apparatus (manufactured by Tosoh, HLC-8120, column used: GPC LF-804 manufactured by SHOdex) was used, a sample injection amount was 50 μL, and a solvent flow rate was 0.5 mL. / Min at 40 ° C. The weight average molecular weight of the polyimide precursor was the same as that of the sample, and the polystyrene standard sample (weight average molecular weight: 364,700, 204,000, 103,500, 44,360, 27,500, 13,030, 6,300, 3,070) as the standard polystyrene conversion value. The elution time was compared with a calibration curve to determine a weight average molecular weight.
<Viscosity of polyimide precursor solution>
The viscosity of the polyimide precursor solution was measured using a viscometer (for example, TVE-22HT, Toki Sangyo Co., Ltd.) at 25 ° C. with a sample volume of 0.8 ml.

<Weight average molecular weight of polyimide>
15 mg of the polyimide powder is immersed in 15000 mg of N-methylpyrrolidone (NMP) and stirred for 3 to 60 hours at a rotation speed of 200 rpm with a stirrer while heating to 60 ° C. in a water bath until visual confirmation of dissolution. As a result, an NMP solution having a concentration of 0.1% by weight was obtained. The solution was filtered through a syringe filter (pore size: 0.45 μm), and using a 30 mmol% LiBr-NMP solution having a water content of 500 ppm or less as a developing solvent, a GPC device (manufactured by Tosoh, HLC-8120, detector: differential) Refractive index (RID) detector, column used: two GPC LF-804 manufactured by SHODEX connected in series), sample injection amount 50 μL, solvent flow rate 0.4 mL / min, column temperature 37 ° C., detector temperature 37 ° C. The measurement was performed under the following conditions. The weight average molecular weight of the polyimide was the same as that of the polystyrene standard sample (weight average molecular weight: 364,700, 204,000, 103,500, 44,360,27,500, 13,030, 6,300,3, 070) as a standard polystyrene conversion value. The elution time was compared with a calibration curve to determine a weight average molecular weight.
<Viscosity of polyimide solution>
The viscosity of the polyimide solution was measured using a viscometer (for example, TVE-22HT, Toki Sangyo Co., Ltd.) at 25 ° C. with a sample volume of 0.8 ml.

<Average particle size of polyimide material (polyimide powder)>
The polyimide material (polyimide powder) was observed with an optical microscope (manufactured by Keyence, Digital Microscope VHX-5000) at a magnification of 100 times, and randomly extracted 150 polyimide material particles from the observed image, The particle diameter of each of the extracted particles was measured, and the average value was calculated to be the average particle diameter of the polyimide material.
In addition, when the particle shape of the polyimide material was not spherical, the major axis was measured.

<Amount of residual solvent in polyimide film>
After specifying the type of residual solvent in the polyimide film, the content of the specified residual solvent was quantified.
[Specification of residual solvent type]
The type of the residual solvent was identified using a GC-MS connected to a purge & trap device (heat desorption device).
A sample tube containing 10 mg of a polyimide film was set in a purge & trap device (product name: JTD505-III, Nippon Kagaku Kogyo Co., Ltd.), and the gas generated by heating at 200 ° C. for 30 minutes and heating at −60 ° C. Was collected at a temperature of 315 ° C. and sent to a GC-MS for qualitative analysis of the components of the generated organic gas.
(Purge & trap equipment conditions)
1:10 total split ratio (introduction / displacement)
Carrier gas helium 1.0ml / min quantitative (GC-MS condition)
Apparatus name: GC-MS apparatus (Agilent, 6890/5973 GC / MS)
Column: UA-5 Inner diameter 250 μm × Length 30 m × Film thickness 0.25 μm (Frontier Lab) )
[Quantification of residual solvent]
A polyimide film is added to N, N-dimethylformamide (DMF) so that the concentration of the polyimide film is 5% by mass, and a polyimide film / N, N-dimethylformamide (DMF) solution is prepared. , An internal standard solution (0.2% by mass anisole / DMF solution) was added to prepare a sample solution. The sample solution was subjected to a GC-MS measurement under the following conditions using a GC-MS device (for example, Agilent, 6890/5973 GC / MS). The GC-MS measurement was performed three times, and the measurement result was an average value of the three measurements.
(GC conditions)
Column: InertCapWax inner diameter 250 μm × length 30 m × film thickness 0.25 μm (manufactured by GL Sciences)
Sample injection amount 0.2uL, split ratio 50: 1, carrier gas helium 94.3kPa constant pressure, injection port temperature 250 ° C, heating condition 40 ° C (holding 5 minutes) → 5 ° C / min → 120 ° C → 20 ° C / min → 240 ° C (hold for 6 minutes), transfer line temperature 250 ° C
(MS condition)
Ionization method EI, measurement mode SIM, ion source temperature 250 ° C, quadrupole temperature 150 ° C, ionization voltage 70eV
(Quantitative ion)
DMAc m / z = 72,87
Dichloromethane m / z = 49,84
Ethyl acetate m / z = 43,88
Butyl acetate m / z = 43,56,73
PGMEA m / z = 45,90
Anisole m / z = 93,108

For example, when the residual solvent is DMAc, each DMAc (measurement target compound) / DMF solution prepared so that the DMAc content is 0.01% by mass, 0.05% by mass, and 0.1% by mass, respectively. GC-MS measurement was performed on each calibration curve solution prepared by adding an internal standard solution in the same manner as in the sample solution described above, and a calibration curve was created. Note that the GC-MS measurement was performed three times, and the measurement result was an average value of the three measurements.
Then, based on the calibration curve, the content of DMAc was calculated as a mass ratio to the polyimide film.
When two or more kinds of residual solvents are contained, a calibration curve solution is prepared for each residual solvent as in the above-mentioned DMAc, and a calibration curve created from the measurement results of each calibration curve solution by GC-MS measurement. The line was referenced.

<Residual solvent amount of polyimide material>
The amount of the residual solvent in the polyimide material was measured in the same manner as in the above-mentioned method for measuring the amount of the residual solvent in the polyimide film except that the polyimide material was used instead of the polyimide film.

<Total light transmittance of polyimide film>
According to JIS K7361-1, it was measured by a haze meter (HM150, manufactured by Murakami Color Research Laboratory).

<Static bending test (2mm, 24 hours standing)>
Hereinafter, the method of the static bending test will be described with reference to FIG.
A test piece 1 of a polyimide film cut into a size of 15 mm × 40 mm was bent at a position corresponding to half of the long side, and both ends of the long side of the test piece 1 were sandwiched between metal pieces 2 (100 mm × 30 mm × 2 mm) having a thickness of 2 mm from above and below. The test piece 1 and the metal piece 2 were fixed with tape so that the overlap between the upper and lower surfaces of the metal piece 2 was 10 mm each. The metal piece 2 to which the test piece 1 was fixed was sandwiched between glass plates (100 mm × 100 mm × 0.7 mm) 3 a and 3 b from above and below, and the test piece 1 was fixed in a state of being bent at an inner diameter of 2 mm. At that time, dummy test pieces 4a and 4b were sandwiched between portions of the metal piece 2 where the test piece 1 was not provided, and fixed with tape so that the glass plates 3a and 3b were parallel.
The test piece fixed in the bent state in this manner was allowed to stand for 24 hours in an environment of 60 ± 2 ° C. and 93 ± 2% relative humidity (RH), and then the glass plate and the tape for fixing the test piece were removed. The force on the specimen was released. Thereafter, one end of the test piece was fixed, and the internal angle of the test piece was measured 30 minutes after the force applied to the test piece was released.
In addition, when the film completely returns to the original state without being affected by the static bending test, the internal angle is 180 °.
(Evaluation criteria)
It was fixed in a state of bending at an inner diameter of 2 mm, and was subjected to a static bending test under a more severe condition than the conventional technology of standing for 24 hours in an environment of 60 ± 2 ° C. and 93 ± 2% relative humidity (RH). The interior angles of the test pieces were evaluated as follows. A and B have good static bending resistance, but A is more excellent.
A: 110 ° or more B: 90 ° or more and less than 110 ° C: less than 90 °

<Dynamic bending test (MIT reciprocating bending test)>
A MIT tester (manufactured by Toyo Seiki Seisaku-sho, MIT D-2) was used to cut a polyimide film test piece cut into a size of 15.0 mm wide × 110 mm long in accordance with JIS 8115-2001. Under the conditions of a bending radius of 1 mm and a load of 500 g, the number of reciprocating bendings until the test piece was broken was measured. The reciprocating bending test was performed three times, and an average value of the number of reciprocating bendings of the three test results was obtained.
(Evaluation criteria)
AA, A and B have good dynamic bending resistance, but AA and A are more excellent.
AA: 50,000 or more times A: 45,000 to less than 50,000 times B: 35,000 to less than 45,000 times C: less than 35,000 times

<YI value (yellowness) of polyimide film>
The YI value was measured using an auxiliary illuminant C and a two-degree visual field by a spectral colorimetric method using an ultraviolet-visible near-infrared spectrophotometer (JASCO Corporation V-7100) according to JIS K7373-2006. , Tristimulus values X, Y, and Z in the XYZ color system are determined based on the transmittance measured in the range of 250 nm or more and 800 nm or less at 1 nm intervals, and the values of X, Y, and Z are calculated from the following equations. Calculated.
YI = 100 (1.2767X-1.0592Z) / Y

<Thickness measurement method>
A total of 5 film thicknesses at the four corners and the center of a polyimide film test piece cut into a size of 10 cm × 10 cm were measured using a digital linear gauge (model PDN12 digital gauge manufactured by Ozaki Corporation), and the measured values were measured. Was taken as the thickness of the polyimide film.

<Tensile modulus of polyimide film>
A test piece of a polyimide film cut into a size of 15 mm × 40 mm was conditioned at a temperature of 25 ° C. and a relative humidity of 60% for 2 hours, and the tensile speed was set to 10 mm / min and the distance between chucks was set to 20 mm in accordance with JIS K7127. And the tensile modulus at 25 ° C. were measured. A tensile tester (Shimadzu Corporation: Autograph AG-X 1N, load cell: SBL-1KN) was used.

<Pencil hardness>
The pencil hardness was determined by conditioning a measurement sample at a temperature of 25 ° C. and a relative humidity of 60% for 2 hours, and then using a pencil for test specified by JIS-S-6006, using a pencil scratching film made by Toyo Seiki Co., Ltd. A pencil hardness test (a load of 0.98 N) specified in JIS K5600-5-4 (1999) was performed on the film surface using a tester to evaluate the highest pencil hardness without scratching.

(Synthesis example 1)
Dissolved N, N-dimethylacetamide (DMAc) (2903 g) and 1,3-bis (3-aminopropyl) tetramethyldisiloxane (AprTMOS) (15.9 g) in a 5 L separable flask The solution was put into the solution, and the temperature of the solution was controlled at 30 ° C., and 4,4 ′-(hexafluoroisopropylidene) diphthalic anhydride (6FDA) (14.6 g) was added. And gradually stirred for 30 minutes with a mechanical stirrer. Thereto, 2,2′-bis (trifluoromethyl) benzidine (TFMB) (387 g) was added, and after confirming complete dissolution, 4,4 ′-(hexafluoroisopropylidene) diphthalic anhydride ( 6FDA) (548 g) was gradually added in several portions so that the temperature rise was 2 ° C. or less, to synthesize a polyimide precursor A solution (solid content: 25% by mass) in which the polyimide precursor A was dissolved. The molar ratio of TFMB and AprTMOS (TFMB: AprTMOS) used for the polyimide precursor A was 95: 5.

(Synthesis example 2)
A polyimide precursor A solution was obtained in the same manner as in Synthesis Example 1.
Under a nitrogen atmosphere, the above polyimide precursor A solution (400 g) cooled to room temperature was added to a 5 L separable flask. Thereto, dehydrated N, N-dimethylacetamide (109 g) was added, and the mixture was stirred until it became uniform. Next, pyridine (41.4 g) as a catalyst and acetic anhydride (53.4 g) were added, and the mixture was stirred at room temperature for 24 hours to synthesize a polyimide A solution.
Butyl acetate (406 g) was added to the obtained polyimide A solution, and the mixture was stirred until it became uniform. Then, t-butanol (3000 g) was gradually added to obtain a white slurry. The process of filtering the slurry, washing the slurry in a beaker containing isopropyl alcohol (130 g), and then filtering is repeated 18 times, and dried at 110 ° C. using a vacuum dryer to obtain polyimide A1 (polyimide material, polyimide material). Powder).
The white slurry obtained by gradually adding t-butanol (3000 g) was filtered to obtain a polyimide powder (0 th time), and the isopropyl alcohol was washed 5 times, 10 times, 13 times, and 15 times. When the amount of residual solvent was confirmed for each of the polyimide powders obtained after the repetition, 0 times: 16754 ppm, after 5 times: 2500 ppm, after 10 times: 220 ppm, after 13 times: 95 ppm, after 15 times, 50 ppm Met.
The weight average molecular weight of the polyimide A1 measured by GPC was 175,000. The average particle size of the polyimide A1 was 250 μm.
When the residual solvent amount of the polyimide A1 was confirmed, the type of the residual solvent was only DMAc, and the residual solvent amount was 17 ppm for DMAc.

(Comparative Synthesis Example 1)
A polyimide A solution was obtained in the same manner as in Synthesis Example 2.
The obtained polyimide A solution (346.4 g) was transferred to a 5 L separable flask, and normal-butyl acetate (hereinafter, referred to as butyl acetate) (235.3 g) was added and stirred until uniform. Next, methanol (523.5 g) was gradually added to obtain a slightly turbid solution. Methanol (1.221 kg) was added all at once to the turbid solution to obtain a white slurry. The slurry was filtered and washed five times with methanol to obtain polyimide CA1 (65.8 g).
The average particle size of the polyimide CA1 was 230 μm.
When the residual solvent amount of the polyimide CA1 was confirmed, the type of the residual solvent was only DMAc, and the residual solvent amount was 2500 ppm for DMAc.

(Synthesis Examples 3 and 4, Comparative Synthesis Examples 2 and 3)
A polyimide A solution was obtained in the same manner as in Synthesis Example 2.
Butyl acetate (406 g) was added to the obtained polyimide A solution, and the mixture was stirred until it became uniform. Then, t-butanol (3000 g) was gradually added to obtain a white slurry. Filtering the slurry, washing the slurry in a beaker containing IPA (130 g), and then filtering, was repeated in the same manner as in Synthesis Example 1 except that the steps of polyimide A2 and A3, In addition, polyimides CA2 and CA3 were obtained.
Polyimide A2 had an average particle size of 240 μm and a residual solvent amount of DMAc of 50 ppm.
The polyimide A3 had an average particle size of 230 μm and a residual solvent content of 95 ppm DMAc.
The polyimide CA2 had an average particle size of 250 μm and a residual solvent amount of DMAc of 220 ppm.
The polyimide CA3 had an average particle size of 240 μm and a residual solvent amount of DMAc of 2500 ppm.

(Examples 1-4, Comparative Examples 1-2)
By using the polyimide A1 of Synthesis Example 2 and performing the following procedures (C1) to (C3), polyimide films having the thicknesses shown in Table 1 were produced.
(C1) Dichloromethane was added to the polyimide A1 so that the solid concentration of the polyimide A1 was 17% by mass to prepare a polyimide A1 dichloromethane solution having a solid content of 17% by mass. The viscosity at 25 ° C. of the polyimide A1 dichloromethane solution (solid content: 17% by mass) was 4,600 cps.
(C2) A polyimide oven A1 dichloromethane solution (solid content concentration: 17% by mass) is circulated on a sheet-like support (thickness: 100 μm, SUS304, SUS304 CSP-H-TA, manufactured by Nisshin Steel Co., Ltd.) to be described below in a circulating oven. The film was dried so as to have a film thickness as shown in Table 1 after drying in the air, and after natural drying, the polyimide resin coating film was peeled off.
(C3) The peeled polyimide resin coating film was cut into a size of 150 mm × 200 mm. Using two metal frames (external dimensions 150 mm × 200 mm, internal dimensions 130 mm × 180 mm), the cut polyimide resin coating was sandwiched, and the metal frame and the polyimide resin coating were fixed with a fixing jig. The fixed polyimide resin coating film was dried in a circulating oven at a heating temperature (° C.) and a time (minute) shown in Table 1 to produce a polyimide film.
Table 1 shows the evaluation results of the obtained polyimide films.

(Examples 5 to 6, Comparative Examples 3 to 5)
By using the polyimide precursor A solution of Synthesis Example 1 and performing the following procedures (H1) to (H2), polyimide films having the thicknesses shown in Table 1 were produced.
(H1) The polyimide precursor A solution (solid content 25% by mass) of Synthesis Example 1 was applied to a sheet-like support (SUS304 CSP-H-TA, thickness: 100 μm, SUS304, manufactured by Nissin Steel Co., Ltd.). The film was heated so that the film thickness after heating under a nitrogen stream described below was applied to the film thickness shown in Table 1, and the support and the applied polyimide precursor A solution were heated at 40 ° C. for 60 minutes in a circulation oven. After drying, the coating was dried at 120 ° C. for 15 minutes to form a polyimide precursor resin coating, and the polyimide precursor resin coating was peeled off.
(H2) The peeled polyimide precursor resin coating film was cut into a size of 150 mm × 200 mm. Using two metal frames (external dimensions 150 mm x 200 mm, internal dimensions 130 mm x 180 mm), the cut polyimide precursor resin coating was sandwiched, and the metal frame and the polyimide precursor resin coating were fixed with a fixing jig. . The immobilized polyimide precursor resin coating film was heated in an oven under a nitrogen stream (oxygen concentration: 100 ppm or less) at a heating rate of 10 ° C./min to a heating temperature (° C.) shown in Table 1, and at that temperature. Heating was performed for the time (minute) shown in Table 1 to form a polyimide film.

* 1: Boiling point of less than 100 ° C * 2: Boiling point of 100 ° C or more dichloromethane: Boiling point of 40 ° C
DMAc (dimethylacetamide): Boiling point 165.5 ° C

(Comparative Example 6)
Polyimide CA1 of Comparative Synthesis Example 1 was dissolved in a mixed solvent of butyl acetate and PGMEA (8: 2, volume ratio) to prepare a polyimide CA1 solution having a solid content of 25% by mass. The viscosity at 25 ° C. of the polyimide CA1 solution (solid content: 25% by weight) was 40,000 cps.
Using the polyimide CA1 solution obtained as described above, the following procedures (iv) to (vi) were performed to produce a polyimide film having a thickness of 50 μm.
(Iv) The polyimide CA1 solution was applied on glass and dried in a circulating oven at 120 ° C. for 10 minutes.
(V) Under a nitrogen stream (oxygen concentration: 100 ppm or less), the temperature was raised to 250 ° C. at a rate of 10 ° C./min, kept at 250 ° C. for 1 hour, and then cooled to room temperature.
(Vi) The polyimide film was peeled off from the glass to obtain a polyimide film.

(Comparative Example 7)
By using the polyimide precursor A solution of Synthesis Example 1 and performing the following procedures (i) to (iii), polyimide films having the thicknesses shown in Table 2 were produced.
(I) The polyimide precursor A solution was applied on glass and dried in a circulating oven at 120 ° C. for 10 minutes.
(Ii) Under a nitrogen stream (oxygen concentration: 100 ppm or less), the temperature was raised to 300 ° C. at a rate of 10 ° C./min, kept at 300 ° C. for 60 minutes, and then cooled to room temperature.
(Iii) It was peeled off from the glass to obtain each polyimide film.

* 2: DMAc (dimethylacetamide) having a boiling point of 100 ° C. or higher: 165.5 ° C. boiling point
Butyl acetate: Boiling point 126 ° C
PGMEA (propylene glycol monomethyl ether acetate): Boiling point 145 ° C

(Examples 7-8, Comparative Examples 8-9)
In Example 1, instead of using the polyimide A1 of Synthesis Example 2, the same as Example 1 except that the polyimides A2 and A3 of Synthesis Examples 3 to 4 and the polyimides CA2 and CA3 of Comparative Synthesis Examples 2 to 3 were used, respectively. Then, polyimide films having the thicknesses shown in Table 3 were produced.
Table 3 shows the evaluation results of the obtained polyimide films.

(Examples 9 to 11)
By using the polyimide A1 of Synthesis Example 2 and performing the following procedures (C1 ′) to (C3 ′), polyimide films having the thicknesses shown in Table 4 were produced.
(C1 ′) Ethyl acetate (boiling point: 77 ° C.) was added to the polyimide A1 so that the solid concentration of the polyimide A1 was 17% by mass to prepare a polyimide A1 ethyl acetate solution having a solid content of 17% by mass. The viscosity at 25 ° C. of the polyimide A1 ethyl acetate solution (solid content: 17% by mass) was 4,800 cps.
(C2 ′) A polyimide A1 ethyl acetate solution (solid content: 17% by mass) is circulated on a sheet-shaped support (thickness: 100 μm, SUS304, SUS304 CSP-H-TA, manufactured by Nissin Steel Co., Ltd.) to be described later. The coating was performed so that the film thickness after drying in the oven was as shown in Table 4, and after natural drying, the polyimide resin coating film was peeled off.
(C3 ′) The peeled polyimide resin coating film was cut into a size of 150 mm × 200 mm. Using two metal frames (external dimensions: 150 mm × 200 mm, internal dimensions: 130 mm × 180 mm), the cut polyimide resin coating film was sandwiched, and the metal frame and the polyimide resin coating film were fixed with a fixing jig. The fixed polyimide resin coating film was dried in a circulation oven at a heating temperature (° C.) and a time (minute) shown in Table 4 to produce a polyimide film.
Table 4 shows the evaluation results of the obtained polyimide films.

(Examples 12 to 14, Comparative Example 10)
By using the polyimide A1 of Synthesis Example 2 and performing the following procedures (C1 ″) to (C3 ″), polyimide films having the thicknesses shown in Table 4 were produced.
(C1 ″) Butyl acetate (boiling point: 126 ° C.) was added to the polyimide A1 so that the solid concentration of the polyimide A1 was 17% by mass to prepare a polyimide A1 butyl acetate solution having a solid content of 17% by mass. The viscosity at 25 ° C. of the A1 butyl acetate solution (solid content 17% by mass) was 5000 cps.
(C2 ″) A polyimide butyl acetate solution (solid content: 17% by mass) is circulated on a sheet-like support (thickness: 100 μm, SUS304, SUS304 CSP-H-TA, manufactured by Nissin Steel Co., Ltd.) as described below. The coating was performed so that the film thickness after drying in the oven was as shown in Table 4, and after natural drying, the polyimide resin coating film was peeled off.
(C3 ″) The peeled polyimide resin coating film was cut out to a size of 150 mm × 200 mm. The polyimide resin coating film cut out using two metal frames (outer size 150 mm × 200 mm, inner size 130 mm × 180 mm). The metal frame and the polyimide resin coating were fixed with a fixing jig, and the fixed polyimide resin coating was dried in a circulating oven at a heating temperature (° C.) and a time (minute) shown in Table 4 to obtain a polyimide. A film was prepared.
Table 4 shows the evaluation results of the obtained polyimide films.

* 1: Boiling point of less than 100 ° C * 2: Boiling point of 100 ° C or more ethyl acetate: Boiling point of 77 ° C
Butyl acetate: Boiling point 126 ° C
DMAc (dimethylacetamide): Boiling point 165.5 ° C

(Synthesis Examples 5 to 10)
The same procedure as in Synthesis Example 1 was carried out except that the molar ratio of TFMB and AprTMOS (TFMB: AprTMOS) used for synthesis of the polyimide precursor A of Synthesis Example 1 was changed from 95: 5 as shown in Table 5. Thus, polyimide precursor A4 to A9 solutions were obtained.
In the synthesis of the polyimide of Synthesis Example 2, polyimide A4 to A9 (polyimide material, polyimide powder) were prepared in the same manner as in Synthesis Example 2 except that the polyimide precursor A solution was used instead of the polyimide precursor A solution. Body).
Table 5 shows the weight average molecular weight and residual solvent (DMAc) amount of each of the polyimides A4 to A9 measured by GPC.

(Examples 15 to 20)
Instead of using the polyimide A1 in Example 1, except that each of the polyimides A4 to A9 obtained in Synthesis Examples 5 to 10 was used, the same procedure as in Example 1 was performed to obtain the thickness shown in Table 6. Polyimide films were prepared respectively.
Table 6 shows the evaluation results of the obtained polyimide films.

(Synthesis Examples 11 to 17)
Synthesis Example 1 except that in the synthesis of the polyimide precursor A of Synthesis Example 1, TFMB used as a diamine containing no Si was changed to use an equimolar amount of diamine 1 shown in Table 7 with TFMB. In the same manner as in, polyimide precursor A10 to A16 solutions were obtained, respectively.
In the synthesis of the polyimide of Synthesis Example 2, polyimide A10 to A16 (polyimide material, polyimide powder) were prepared in the same manner as in Synthesis Example 2 except that the polyimide precursor A solution was used instead of the polyimide precursor A solution. Body).
Table 7 shows the weight average molecular weight and residual solvent (DMAc) amount of each of the polyimides A10 to A16 measured by GPC.

(Examples 21 to 27)
Instead of using the polyimide A1 in Example 1, except that each of the polyimides A10 to A16 obtained in Synthesis Examples 11 to 17 was used, the same procedure as in Example 1 was performed to obtain the thickness shown in Table 8. Polyimide films were prepared respectively.
Table 8 shows the evaluation results of the obtained polyimide films.

(Synthesis Example 18)
In the synthesis of the polyimide precursor A of Synthesis Example 1, except that half of 6FDA used as the acid dianhydride was changed to use pyromellitic dianhydride in an equimolar amount to 6FDA. Similarly, a polyimide precursor A17 solution (solid content: 25% by mass) was synthesized.
The molar ratio of TFMB and AprTMOS (TFMB: AprTMOS) used for the polyimide precursor A17 was 95: 5.
In the synthesis of polyimide of Synthesis Example 2, polyimide A17 (polyimide material, polyimide powder) was obtained in the same manner as in Synthesis Example 2 except that a polyimide precursor A17 solution was used instead of the polyimide precursor A solution. Was.
The weight average molecular weight of the polyimide A17 measured by GPC was 176,000.
When the residual solvent amount of the polyimide A17 was confirmed, the type of the residual solvent was only DMAc, and the residual solvent amount was 22 ppm for DMAc.

(Synthesis Example 19)
In the synthesis of the polyimide precursor A of Synthesis Example 1, except that 6FDA used as an acid dianhydride was changed to use an equimolar amount of 4,4′-oxydiphthalic anhydride with 6FDA, In the same manner as in Example 1, a polyimide precursor A18 solution was obtained. The molar ratio of TFMB and AprTMOS (TFMB: AprTMOS) used for the polyimide precursor A18 was 95: 5.
In the synthesis of the polyimide of Synthesis Example 2, polyimide A18 (polyimide material, polyimide powder) was obtained in the same manner as in Synthesis Example 2 except that the polyimide precursor A18 solution was used instead of the polyimide precursor A solution. Was.
The weight average molecular weight of the polyimide A18 measured by GPC was 178,000.
When the residual solvent amount of the polyimide A18 was confirmed, the type of the residual solvent was only DMAc, and the residual solvent amount was 20 ppm of DMAc.

(Examples 28 to 29)
Instead of using the polyimide A1 in Example 1, except that each of the polyimides A17 to A18 obtained in Synthesis Examples 18 to 19 was used, the same procedure as in Example 1 was performed, so that the thicknesses shown in Table 8 were obtained. Polyimide films were prepared respectively.
Table 9 shows the evaluation results of the obtained polyimide films.

(Examples 30 to 58: Production of laminate)
To a 40% by mass solution of pentaerythritol triacrylate in methyl isobutyl ketone, 10 parts by mass of 1-hydroxy-cyclohexyl-phenyl-ketone (Irgacure 184, manufactured by BASF) was added based on 100 parts by mass of pentaerythritol triacrylate. A resin composition for a coat layer was prepared.
The resin composition for a hard coat layer was applied on each of the polyimide films of Examples 1 to 29, and was irradiated with ultraviolet rays at a light exposure of 200 mJ / cm ² under a nitrogen stream to be cured to form a cured film having a thickness of 10 μm. The laminated body was manufactured.
Since the polyimide film contains silicon atoms, the adhesion to the hard coat layer was also good.

Claims (13)

Containing a polyimide having a structure represented by the following general formula (1),
As a residual solvent in the film, the content of the organic solvent having a boiling point under 1 atm of less than 100 ° C. is 2000 ppm or less, and the content of the organic solvent having a boiling point at 1 atm of 100 ° C. or more is 100 ppm or less. Yes,
A polyimide film having a total light transmittance of 85% or more as measured according to JIS K7361-1.
(In the general formula (1), R ¹ represents a tetravalent group that is a tetracarboxylic acid residue having an aromatic ring or an aliphatic ring; R ² represents a divalent group that is a diamine residue; 2.5 to 50 mol% of the total amount of ² are diamine residues having a silicon atom in the main chain, and 50 to 97.5 mol% do not have a silicon atom and are aromatic. A diamine residue having a ring or an aliphatic ring, and n represents the number of repeating units.)   2. The polyimide film according to claim 1, wherein a tensile modulus at 25 ° C. of a 15 mm × 40 mm test piece measured at 25 ° C. based on JIS K7127 at a tensile speed of 10 mm / min and a distance between chucks of 20 mm is 1.8 GPa or more. .   3. The polyimide film according to claim 1, wherein a value obtained by dividing a yellowness calculated according to JIS K7373-2006 by a film thickness (μm) is 0.10 or less. 4. R ¹ in the general formula (1) is a cyclohexanetetracarboxylic dianhydride residue, a cyclopentanetetracarboxylic dianhydride residue, dicyclohexane-3,4,3 ′, 4′-tetracarboxylic dianhydride residue. Anhydride residue, cyclobutanetetracarboxylic dianhydride residue, pyromellitic dianhydride residue, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride residue, 2,2 ′, 3 3,3′-biphenyltetracarboxylic dianhydride residue, 4,4 ′-(hexafluoroisopropylidene) diphthalic anhydride residue, 3,4 ′-(hexafluoroisopropylidene) diphthalic anhydride residue, 3,3 ′-(hexafluoroisopropylidene) diphthalic anhydride residue, 4,4′-oxydiphthalic anhydride residue, and 3,4′-oxydiphthalic anhydride residue Polyimide film is also one tetravalent group, according to any one of claims 1 to 3. In R ² in the general formula (1), a diamine residue having no aromatic atom or an aromatic ring without the silicon atom is a trans-cyclohexanediamine residue, trans-1,4-bismethylenecyclohexane. Diamine residue, 4,4'-diaminodiphenylsulfone residue, 3,4'-diaminodiphenylsulfone residue, 2,2-bis (4-aminophenyl) propane residue, 3,3'-bis (trifluoro Methyl) -4,4 ′-[(1,1,1,3,3,3-hexafluoropropane-2,2-diyl) bis (4,1-phenyleneoxy)] dianiline residue, 2,2- Bis [3- (3-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane residue, 2,2-bis [4- (4-aminophenoxy) phenyl] -1, 1,1 5. The compound according to claim 1, which is at least one divalent group selected from the group consisting of a 3,3,3-hexafluoropropane residue and a divalent group represented by the following general formula (2). The polyimide film according to any one of the preceding claims.
(In the general formula (2), R ³ and R ⁴ each independently represent a hydrogen atom, an alkyl group, or a perfluoroalkyl group.) In the general formula (1), R ² is a divalent group that is at least one selected from a diamine residue having no silicon atom and a diamine residue having one or two silicon atoms in the main chain. Wherein 2.5 mol% or more and 50 mol% or less of the total amount of R ² are diamine residues having one or two silicon atoms in the main chain, and 50 mol% or more and 97.5 mol% or less The polyimide film according to any one of claims 1 to 5, wherein the polyimide film does not have a silicon atom and is a diamine residue having an aromatic ring or an aliphatic ring. It is a polyimide material for producing a polyimide film according to any one of claims 1 to 6,
It has a structure represented by the general formula (1), and has a content of an organic solvent having a boiling point of less than 100 ° C. under 1 atm at 2000 ppm or less as a residual solvent and a boiling point at 1 atm of 100. A polyimide material having an organic solvent content of 100 ° C or higher at 100 ° C or lower.   A laminate comprising the polyimide film according to claim 1 and a hard coat layer containing at least one polymer of a radically polymerizable compound and a cationically polymerizable compound.   A display member, which is the polyimide film according to any one of claims 1 to 6, or the laminate according to claim 8.   The display member according to claim 9, which is for a flexible display. The polyimide film according to any one of claims 1 to 6 or the laminate according to claim 8,
A transparent electrode composed of a plurality of conductive portions, disposed on one surface side of the polyimide film or the laminate,
A touch panel member comprising: a plurality of extraction lines electrically connected to at least one side of an end of the conductive portion. The polyimide film according to any one of claims 1 to 6 or the laminate according to claim 8,
A liquid crystal display device comprising: a liquid crystal display portion having a liquid crystal layer between opposing substrates, which is disposed on one surface side of the polyimide film or the laminate. The polyimide film according to any one of claims 1 to 6 or the laminate according to claim 8,
An organic electroluminescent display device, comprising: an organic electroluminescent display portion having an organic electroluminescent layer between opposing substrates, the organic electroluminescent display portion being arranged on one surface side of the polyimide film or the laminate.