JP7139715B2 - Polyimide film, laminate, display surface material, touch panel member, liquid crystal display device, and organic electroluminescence display device - Google Patents

Description

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

Thin plate glass is excellent in hardness and heat resistance, but has drawbacks such as being difficult to bend, being easily broken if dropped, and having problems with workability, and being heavier than plastic products. For this reason, in recent years, resin products such as resin substrates and resin films have been replacing glass products in terms of workability and weight reduction, and research has been conducted on resin products that can serve as substitutes for glass.

On the other hand, with the rapid progress of displays such as liquid crystal and organic EL, and electronics such as touch panels, there has been a demand for thinner, lighter, and more flexible devices. Conventionally, these devices have various electronic elements, such as thin transistors and transparent electrodes, formed on thin sheet glass. By replacing this thin sheet glass with a resin film, the impact resistance of the panel itself is enhanced. , flexibility, thinness and weight reduction can be achieved.

Polyimide resin is widely used as an insulating material for electronic components, such as chip coating films in semiconductor devices and base materials for flexible printed wiring boards, due to its excellent heat resistance, dimensional stability, and insulating properties. In recent years, research has also been conducted on resin products using polyimide resins with improved transparency as substitutes for glass.
However, since polyimide resins generally have absorption in the ultraviolet region, there is a problem that they tend to discolor when used outdoors, and there is a demand for improved weather resistance.
Patent Document 1 describes that, as a resin film having high transparency even after a light irradiation test, for example, a polyimide-based polymer having high transparency is used and an ultraviolet absorber is included in the resin film. ing.

WO2017/014279

However, a conventional polyimide film containing an ultraviolet absorber may have an increased haze value when stored for a long period of time.
In addition, the flexible displays installed in mobile devices with foldable screens are required to have no display defects even when repeatedly bent. Bending resistance (hereinafter sometimes referred to as dynamic bending resistance) is required.

The present invention has been made in view of the above problems, and provides a resin film that has excellent weather resistance, suppresses an increase in haze value after long-term storage, and has excellent bending resistance when repeatedly bent. The main purpose is to provide
Further, the present invention provides a laminate having the resin film, a display surface material that is the resin film or the laminate, and a touch panel member, a liquid crystal display device, and an organic electroluminescence display having the resin film or the laminate. The purpose is to provide an apparatus.

The polyimide film of the present invention comprises a polyimide having a structure represented by the following general formula (1),
and an ultraviolet absorber having a linear or branched saturated aliphatic hydrocarbon group having 1 to 8 carbon atoms,
The total light transmittance measured according to JIS K7361-1 is 80% or more.

（一般式（１）において、Ｒ^１は芳香族環又は脂肪族環を有するテトラカルボン酸残基である４価の基を表し、Ｒ^２はジアミン残基である２価の基を表し、Ｒ^２の総量の２．５モル％以上５０モル％以下が、下記一般式（Ａ）で表されるジアミンから２つのアミノ基を除いた残基であり、Ｒ^２の総量の５０モル％以上９７．５モル％以下が、ケイ素原子を有さず、芳香族環又は脂肪族環を有するジアミン残基である。ｎは繰り返し単位数を表す。）

(In 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, and R ^2.5 mol% or more and 50 mol% or less of the total amount of R ² is a residue obtained by removing two amino groups from the diamine represented by the following general formula (A), and 50 mol% or more of the total amount of R 2 97 0.5 mol % or less is a diamine residue having no silicon atom and having an aromatic ring or an aliphatic ring.n represents the number of repeating units.)

（一般式（Ａ）において、Ｌはそれぞれ独立して、直接結合又は－Ｏ－結合を表し、Ｒ^１０はそれぞれ独立して、炭素数１以上８以下の直鎖状又は分岐状の１価の飽和脂肪族炭化水素基を表し、Ｒ^１１はそれぞれ独立して、炭素数１以上８以下の直鎖状又は分岐状の２価の飽和脂肪族炭化水素基を表す。ｋは０～２００の数である。複数あるＬ、Ｒ^１０及びＲ^１１は、それぞれ同一であっても異なっていても良い。）

(In the general formula (A), each L independently represents a direct bond or -O- bond, each R ¹⁰ independently represents a linear or branched monovalent represents a saturated aliphatic hydrocarbon group, each R ¹¹ independently represents a linear or branched divalent saturated aliphatic hydrocarbon group having 1 to 8 carbon atoms, k is a number from 0 to 200; A plurality of L, R ¹⁰ and R ¹¹ may be the same or different.)

In the polyimide film of the present invention, the ultraviolet absorber is at least one selected from benzotriazole-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers and benzoate-based ultraviolet absorbers, and at least one on at least one aromatic ring. A structure in which one hydrogen atom is substituted by a linear or branched monovalent saturated aliphatic hydrocarbon group having 1 to 8 carbon atoms which may contain an -O- bond or -CO-O- bond It is preferable from the viewpoint of suppressing an increase in the haze value of the polyimide film after long-term storage.

The polyimide film of the present invention is a polyimide having a structure represented by the general formula (1), wherein 2.5 mol% or more and less than 10 mol% of the total amount of R ² is represented by the general formula (A). A residue obtained by removing ^two amino groups from a diamine, the remaining R ² being a diamine residue having no silicon atom and having an aromatic ring or an aliphatic ring, more than half are 1,4-cyclohexanediamine residues, trans-1,4-bismethylenecyclohexanediamine residues, 4,4′-diaminodiphenylsulfone residues, 3,4′-diaminodiphenylsulfone residues, A group consisting of a 2,2-bis(4-aminophenyl)propane residue, a 2,2-bis(4-aminophenyl)hexafluoropropane residue, and a divalent group represented by the following general formula (2) At least one divalent group selected from is preferable from the viewpoint of improving bending resistance when repeatedly bent and suppressing a decrease in surface hardness.

（一般式（２）において、Ｒ^３及びＲ^４はそれぞれ独立に、水素原子、アルキル基、またはパーフルオロアルキル基を表す。）

(In 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, k in the general formula (A) in the diamine represented by the general formula (A) is preferably 0 or 1 from the viewpoint of achieving both bending resistance and surface hardness.

The polyimide film of the present invention has a yellowness index of 20.0 or less calculated according to JIS K7373:2006,
The haze value measured in accordance with JIS K7136:2000 is 2.0% or less,
It is preferable that the birefringence in the thickness direction at a wavelength of 590 nm is 0.040 or less from the viewpoint of light transmittance and reduction of optical distortion.

The polyimide film of the present invention, on at least one surface, has an arithmetic mean roughness Ra of 10 nm or less measured in accordance with JIS B0601 to prevent a decrease in transparency, and the polyimide film of the present invention is used for displays. It is preferable from the viewpoint of excellent display visibility when used as a surface material.

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′-oxydiphthalic anhydride At least one tetravalent group selected from the group consisting of residues and 3,4'-oxydiphthalic anhydride residues is preferable from the viewpoint of light transmittance, bending resistance and surface hardness. .

The laminate of the present invention is a laminate comprising the polyimide film of the present invention and a hard coat layer containing at least one polymer of a radical polymerizable compound and a cationically polymerizable compound.

In the laminate of the present invention, the radically polymerizable compound is a compound having two or more (meth)acryloyl groups in one molecule, and the cationically polymerizable compound contains at least one of an epoxy group and an oxetanyl group in one molecule. A compound having two or more groups is preferred from the viewpoints of adhesion, light transmittance and surface hardness.

The present invention provides a display surface material which is the polyimide film of the present invention or the laminate of the present invention.
The display surface material of the present invention can be used for flexible displays.

The present invention, the polyimide film of the present invention, or the laminate of the present invention,
A transparent electrode having a plurality of conductive parts disposed on one surface side of the polyimide film or the laminate;
and a plurality of take-out lines electrically connected to at least one end of the conductive portion.

The present invention, the polyimide film of the present invention, or the laminate of the present invention,
a liquid crystal display portion having a liquid crystal layer between opposing substrates arranged on one surface side of the polyimide film or the laminate;
To provide a liquid crystal display device having

The present invention, the polyimide film of the present invention, or the laminate of the present invention,
an organic electroluminescence display portion having an organic electroluminescence layer between opposing substrates arranged on one side of the polyimide film or the laminate;
To provide an organic electroluminescent display device having

According to the present invention, it is possible to provide a resin film that has excellent weather resistance, suppresses an increase in haze value after long-term storage, and has excellent bending resistance when repeatedly bent.
Further, according to the present invention, there are provided a laminate having the resin film, a surface material for a display that is the resin film or the laminate, and a touch panel member, a liquid crystal display device, and an organic electronic device having the resin film or the laminate. A luminescent display device can be provided.

It is a schematic sectional drawing which shows an example of the laminated body of this invention. 1 is a schematic plan view of one surface of an example of a 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; FIG. FIG. 4 is a cross-sectional view of the touch panel member shown in FIGS. 2 and 3 taken along line A-A'; 1 is a schematic plan view showing an example of a conductive member provided with a laminate of the present invention; FIG. FIG. 4 is a schematic plan view showing another example of a conductive member provided with the laminate of the present invention; It is a schematic sectional drawing which shows another example of the touch-panel member of this invention. 1 is a schematic cross-sectional view showing an example of a liquid crystal display device of the present invention; FIG. 3 is a schematic cross-sectional view showing another example of the liquid crystal display device of the present invention; FIG. 1 is a schematic cross-sectional view showing an example of an organic electroluminescence display device of the present invention; FIG. FIG. 4 is a schematic cross-sectional view showing another example of the organic electroluminescence display device of the present invention;

I. Polyimide film The polyimide film of the present invention comprises a polyimide having a structure represented by the following general formula (1),
and an ultraviolet absorber having a linear or branched saturated aliphatic hydrocarbon group having 1 to 8 carbon atoms,
A polyimide film having a total light transmittance of 80% or more as measured according to JIS K7361-1.

（一般式（１）において、Ｒ^１は芳香族環又は脂肪族環を有するテトラカルボン酸残基である４価の基を表し、Ｒ^２はジアミン残基である２価の基を表し、Ｒ^２の総量の２．５モル％以上５０モル％以下が、下記一般式（Ａ）で表されるジアミンから２つのアミノ基を除いた残基であり、Ｒ^２の総量の５０モル％以上９７．５モル％以下が、ケイ素原子を有さず、芳香族環又は脂肪族環を有するジアミン残基である。ｎは繰り返し単位数を表す。）

(In 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, and R ^2.5 mol% or more and 50 mol% or less of the total amount of R ² is a residue obtained by removing two amino groups from the diamine represented by the following general formula (A), and 50 mol% or more of the total amount of R 2 97 0.5 mol % or less is a diamine residue having no silicon atom and having an aromatic ring or an aliphatic ring.n represents the number of repeating units.)

（一般式（Ａ）において、Ｌはそれぞれ独立して、直接結合又は－Ｏ－結合を表し、Ｒ^１０はそれぞれ独立して、炭素数１以上８以下の直鎖状又は分岐状の１価の飽和脂肪族炭化水素基を表し、Ｒ^１１はそれぞれ独立して、炭素数１以上８以下の直鎖状又は分岐状の２価の飽和脂肪族炭化水素基を表す。ｋは０～２００の数である。複数あるＬ、Ｒ^１０及びＲ^１１は、それぞれ同一であっても異なっていても良い。）

(In the general formula (A), each L independently represents a direct bond or -O- bond, each R ¹⁰ independently represents a linear or branched monovalent monovalent represents a saturated aliphatic hydrocarbon group, each R ¹¹ independently represents a linear or branched divalent saturated aliphatic hydrocarbon group having 1 to 8 carbon atoms, k is a number from 0 to 200; A plurality of L, R ¹⁰ and R ¹¹ may be the same or different.)

In the present invention, the tetracarboxylic acid residue refers to a residue obtained by removing four carboxyl groups from a tetracarboxylic acid, and is the same as a residue obtained by removing an acid dianhydride structure from a tetracarboxylic dianhydride. Represent structure. A diamine residue refers to a residue obtained by removing two amino groups from a diamine.

The polyimide film of the present invention comprises a polyimide having a structure represented by the general formula (1) and an ultraviolet absorber having a linear or branched saturated aliphatic hydrocarbon group having 1 to 8 carbon atoms. By containing them in combination, the increase in haze value after long-term storage is suppressed while having excellent weather resistance, and the dynamic bending resistance is excellent. The reason for this is presumed as follows.
The polyimide film of the present invention has improved weather resistance by containing an ultraviolet absorber. Among them, the polyimide film of the present invention introduces a specific amount of a skeleton derived from the diamine represented by the general formula (A) having a linear or branched saturated aliphatic hydrocarbon group having 1 to 8 carbon atoms. and a combination of a polyimide and an ultraviolet absorber having a linear or branched saturated aliphatic hydrocarbon group having 1 to 8 carbon atoms, the compatibility between the polyimide and the ultraviolet absorber in the polyimide film is considered to be superior. In the polyimide film of the present invention, the excellent compatibility between the polyimide and the ultraviolet absorber makes it difficult for the ultraviolet absorber to bleed out, and the bleedout of the ultraviolet absorber is suppressed even when stored for a long period of time. Therefore, it is considered that the increase in haze value after long-term storage is suppressed.
Further, the polyimide film of the present invention is a polyimide in which a specific amount of a flexible skeleton derived from a diamine represented by the general formula (A) is introduced between rigid molecular skeletons containing an aromatic ring or an aliphatic ring. It is presumed that the inclusion of the film enables stress relaxation due to molecular motion and reduces the stress applied to the film during bending, resulting in excellent dynamic bending resistance.
Furthermore, the polyimide film of the present invention maintains surface hardness by having a rigid molecular skeleton containing an aromatic ring or an alicyclic ring in the polyimide. It can be compatible with bending resistance.

The polyimide film according to the present invention will be described in detail below.
The polyimide film according to the present invention includes a polyimide having a structure represented by the general formula (1), and an ultraviolet absorber having a linear or branched saturated aliphatic hydrocarbon group having 1 to 8 carbon atoms. contains As long as the effect of the present invention is not impaired, it may further contain other components and may have other constitutions.

1. Polyimide Polyimide is obtained by reacting a tetracarboxylic acid component and a diamine component. As the polyimide used in the present invention, a polyimide obtained by obtaining a polyamic acid by polymerization of a tetracarboxylic acid component and a diamine component and then imidizing the polyamic acid is preferable.
A polyimide film according to the present invention contains a polyimide having a structure represented by the general formula (1).
The tetracarboxylic acid residue in R ¹ of the general formula (1) is a residue obtained by removing the 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 the 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-dicarboxyphenyl)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}ketone 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 dianhydride, bis{4-[4-(1,2-dicarboxy)phenoxy]phenyl}sulfide dianhydride, bis{4-[3 -(1,2-dicarboxy)phenoxy]phenyl}sulf dianhydride, 4,4'-(hexafluoroisopropylidene)diphthalic anhydride, 3,4'-(hexafluoroisopropylidene)diphthalic anhydride, 3,3'-(hexafluoroisopropylidene)diphthalic anhydride Acid anhydride, 4,4'-oxydiphthalic anhydride, 3,4'-oxydiphthalic anhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetra Carboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 1,2,3,4-benzenetetracarboxylic dianhydride, 3,4,9,10-perylenetetracarboxylic acid dianhydride, 2,3,6,7-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.
These may be used alone or in combination of two or more.

Among the polyimides having the structure represented by the general formula (1), R ¹ in the general formula (1) is cyclohexanetetracarboxylic acid di anhydride residue, cyclopentanetetracarboxylic dianhydride residue, dicyclohexane-3,4,3′,4′-tetracarboxylic dianhydride residue, cyclobutanetetracarboxylic dianhydride residue, pyromellit acid 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 , 4,4'-oxydiphthalic anhydride residue, and 3,4'-oxydiphthalic anhydride residue.
In R ¹ , the total content of these suitable residues is preferably 50 mol % or more, more preferably 70 mol % or more, and even more preferably 90 mol % or more.
In particular, from the viewpoint of a good balance between light transmittance and surface hardness, R ¹ in the general formula (1) is a 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 More preferably, at least one tetravalent group selected from the group consisting of acid anhydride residues, 4,4'-(hexafluoroisopropylidene) diphthalic anhydride residue, and 4,4'- More preferably, it is at least one tetravalent group selected from oxydiphthalic anhydride residues.

R ¹ in the general formula (1) includes a pyromellitic dianhydride residue, a 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 and cyclohexanetetracarboxylic acid 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 anhydride residue 4,4'-oxydiphthalic anhydride residue, and at least one selected from the group consisting of 3,4'-oxydiphthalic anhydride residue. It is also preferred to use a mixture with a group of carboxylic acid residues (group B). In this case, the content ratio of the tetracarboxylic acid residue group (group A) suitable for improving rigidity and the tetracarboxylic acid residue group (group B) suitable for improving light transmittance is , 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 light transmittance. It is preferably 0.5 mol or more and 9 mol or less, more preferably 0.1 mol or more and 5 mol or less, and still more preferably 0.3 mol or more and 4 mol or less.
Among them, Group B includes fluorine atom-containing 4,4′-(hexafluoroisopropylidene)diphthalic anhydride residues and 3,4′-(hexafluoroisopropylidene)diphthalic anhydride residues. It is preferable to use at least one of them from the viewpoint of improving surface hardness and light transmittance.

In R ² of the general formula (1), the content of residues obtained by removing two amino groups from the diamine represented by the general formula (A) is 2.5 mol% or more of the total amount of R ² and 50 mol. % or less, preferably 2.5 mol % or more and 40 mol % or less from the viewpoint of dynamic bending resistance and surface hardness, and from the viewpoint of dynamic bending resistance and surface hardness and optical properties, It is more preferably 2.5 mol% or more and 20 mol% or less, and from the viewpoint of improving dynamic bending resistance in a high-temperature and high-humidity environment and improving surface hardness, it is still more preferably 2.5 mol% or more and 10 less than mol %.

As the linear or branched monovalent saturated aliphatic hydrocarbon group having 1 to 8 carbon atoms represented by R ¹⁰ in the general formula (A), a straight chain having 1 to 6 carbon atoms Alternatively, it is preferably a branched alkyl group such as methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, t-butyl group, pentyl group, hexyl group and the like. Among them, from the viewpoint of bending resistance, surface hardness and optical properties, R ¹⁰ is preferably a linear or branched alkyl group having 1 to 3 carbon atoms, more preferably a methyl group or an ethyl group.

As the linear or branched divalent saturated aliphatic hydrocarbon group having 1 to 8 carbon atoms represented by R ¹¹ in the general formula (A), a straight chain having 1 to 6 carbon atoms or a branched alkylene group, such as a methylene group, an ethylene group, various propylene groups, and various butylene groups. ¹¹ is preferably a linear or branched alkylene group having 2 to 6 carbon atoms, more preferably a linear or branched alkylene group having 2 to 4 carbon atoms.

k in the general formula (A) is a number of 0 or more and 200 or less, preferably a number of 0 or more and 8 or less, more preferably a number of 0 or more and 2 or less, from the viewpoint of bending resistance, and more It is more preferably 0 or 1. In the case where 2.5 mol% or more and less than 10 mol% of the total amount of R ² in the general formula (1) is a residue obtained by removing two amino groups from the diamine represented by the general formula (A) , When k in the general formula (A) is 0 or 1, it improves dynamic bending resistance in a high-temperature and high-humidity environment while suppressing a decrease in surface hardness, and improves film formability. This is preferable in that irregularities are less likely to occur on the film surface.

L in the general formula (A) is a direct bond or an —O— bond, and is not particularly limited, but is a direct bond from the viewpoint of availability and suppression of an increase in the haze value of the film. is preferred.

The molecular weight of the diamine represented by the general formula (A) is preferably 3000 or less, more preferably 2000 or less, and 1000 or less, from the viewpoint of compatibility between improvement in bending resistance and surface hardness. It is even more preferably 800 or less, even more preferably 500 or less, and particularly preferably 300 or less.
Diamine residues having one or two silicon atoms in the main chain may be used alone or in combination of two or more.

Specific examples of the diamine represented by the general formula (A) include 1,3-bis(3-aminopropyl)tetramethyldisiloxane residue, 1,3-bis(4-aminobutyl)tetramethyl Disiloxane and 1,3-bis (5-aminopentyl) tetramethyldisiloxane is at least one selected from the viewpoint of compatibility between availability and light transmittance and surface hardness, the viewpoint of bending resistance and the film is preferable from the viewpoint of suppressing an increase in the haze value of

The diamine residue having no silicon atom and having an aromatic ring in R ² of the general formula (1) is a residue obtained by removing two amino groups from a diamine having no silicon atom and having an aromatic ring. can do.
Examples of the diamine having an aromatic ring include p-phenylenediamine, m-phenylenediamine, o-phenylenediamine, 3,3′-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether, and 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′ -diaminodiphenyl sulfone, 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-aminophenoxy)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-ditrifluoro methylbenzyl)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-amino phenyl)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-amino phenoxy)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)phenyl]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-aminophenoxy)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]be benzene, 1,4-bis[4-(3-aminophenoxy)-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'-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 part or all of the hydrogen atoms on the aromatic ring of the diamine are fluoro, methyl, methoxy, trifluoromethyl, or trifluoromethoxy groups Diamines substituted with substituents selected from can also be used.
These may be used alone or in combination of two or more.

The diamine residue having no silicon atom and having an alicyclic ring in R ² of the general formula (1) can be a residue obtained by removing two amino groups from a diamine having an alicyclic ring.
Examples of diamines having an aliphatic ring include trans-cyclohexanediamine, trans-1,4-bismethylenecyclohexanediamine, 2,6-bis(aminomethyl)bicyclo[2,2,1]heptane, 2,5 -bis(aminomethyl)bicyclo[2,2,1]heptane and the like.
These may be used alone or in combination of two or more.

50 mol% or more and 97.5 mol% or less of the ^{total amount of R 2 in} the general formula (1) is a diamine residue having no silicon atom and having an aromatic ring or an aliphatic ring. be. In addition, in R ² of the general formula (1), another diamine residue different from the diamine represented by the general formula (A) and the diamine having an aromatic ring or an aliphatic ring and not having a silicon atom does not preclude inclusion. The other diamine residue is preferably 10 mol% or less, more preferably 5 mol% or less, even more preferably 3 mol% or less, particularly 1 mol% of the total amount of R ² The following are preferred. Examples of the other diamine residue include diamine residues having no silicon atoms and no aromatic rings or aliphatic rings.
Among the total amount of R ² (100 mol %), if the residue obtained by removing two amino groups from the diamine represented by the general formula (A) is x mol % (2.5 ≤ x ≤ 50) , 50 mol % or more and 97.5 mol % or less of (100-x mol %) of R ² is preferably a diamine residue having no silicon atom and having an aromatic ring or an aliphatic ring.

As the diamine residue having no silicon atom and having an aromatic ring or an aliphatic ring, among other 1,4-cyclohexanediamine residue, trans-1,4-bismethylenecyclohexanediamine residue, 4,4′-diaminodiphenylsulfone residue, 3,4′-diaminodiphenylsulfone residue, 2,2 -bis (4-aminophenyl) propane residue, 2,2-bis (4-aminophenyl) hexafluoropropane residue, and selected from the group consisting of a divalent group represented by the following general formula (2) At least one divalent group is preferred. In the polyimide having the structure represented by the general formula (1), the total of the preferred diamine residues does not have a silicon atom in the R ² and has an aromatic ring or an aliphatic ring. It is preferably at least 50 mol %, more preferably at least 70 mol %, still more preferably at least 90 mol % of the total amount of the groups.

（一般式（２）において、Ｒ^３及びＲ^４はそれぞれ独立に、水素原子、アルキル基、またはパーフルオロアルキル基を表す。）

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

The polyimide having the structure represented by the general formula (1) improves the dynamic bending resistance of the polyimide film in a high temperature and high humidity environment while suppressing the decrease in surface hardness, and improves the film formability. 2.5 mol % or more and less than 10 mol % of the ^total amount of R A residue obtained by removing two amino groups from the diamine represented, the remaining R ² being a diamine residue having no silicon atom and having an aromatic ring or an aliphatic ring, and the remaining R ² of which more than half are 1,4-cyclohexanediamine residues, trans-1,4-bismethylenecyclohexanediamine residues, 4,4'-diaminodiphenylsulfone residues, 3,4'-diaminodiphenylsulfone residue, 2,2-bis(4-aminophenyl)propane residue, 2,2-bis(4-aminophenyl)hexafluoropropane residue, and a divalent group represented by the general formula (2) It is preferably at least one divalent group selected from the group consisting of (hereinafter sometimes referred to as "at least one divalent group selected from the above group").

Here, the remaining R ² is x mol % ( ² . 5≦x<10), it means that the (100−x) mol% of R ² is more than 90 mol% and 97.5 mol% or less, and more than half of the remaining R ² , R ² in excess of {(100−x)/2} mol %. That is, (100-x) mol% of R ² is ^more than 90 mol% and 97.5 mol% or less is a diamine residue having no silicon atom and having an aromatic ring or an aliphatic ring, More than {(100−x)/2} mol % is preferably at least one divalent group selected from the above group. Among them, the ratio of at least one divalent group selected from the group among the remaining R ² , i.e., the total amount of diamine residues having no silicon atoms and having an aromatic ring or an aliphatic ring The ratio of at least one divalent group selected from the above group when is 100 mol% is preferably 70 mol% or more, and 85 mol% or more, from the viewpoint of surface hardness and light transparency. It is more preferably 95 mol % or more, and particularly preferably 100 mol %. Note that R ² may contain other diamine residues having no silicon atom and having an aromatic ring or an aliphatic ring, different from at least one divalent group selected from the above group. good.

At least one divalent group selected from the above group includes trans-1,4-bismethylenecyclohexanediamine residue, 4,4'-diaminodiphenylsulfone residue, from the viewpoint of surface hardness and light transparency. group, 3,4′-diaminodiphenylsulfone residue, 2,2-bis(4-aminophenyl)propane residue, 2,2-bis(4-aminophenyl)hexafluoropropane residue, and the general formula ( It is preferably at least one divalent group selected from the group consisting of the divalent groups represented by 2). Among the divalent groups represented by the 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 A trifluoromethyl group or a perfluoroethyl group is more preferred. Moreover, as the alkyl group for R ³ and R ⁴ in the 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. As at least one divalent group selected from the group, trans-1,4-bismethylenecyclohexanediamine residue, 4,4'-diaminodiphenylsulfone residue, and the above-mentioned At least one divalent group selected from the group consisting of divalent groups represented by the general formula (2) in which R ³ and R ⁴ in the general formula (2) are perfluoroalkyl groups is more preferable, and in the divalent group represented by the general formula (2), a divalent group in which R ³ and R ⁴ in the general formula (2) are perfluoroalkyl groups is even more preferable.

R ² in the general formula (1) contains a diamine residue having no silicon atom and having an aromatic ring or an aliphatic ring, different from at least one divalent group selected from the group In this case, the content is not particularly limited, but from the viewpoint of surface hardness and light transmittance, it is preferably 30 mol% or less of the total amount (100 mol%) of R ² , and 20 mol% or less. more preferably 10 mol % or less.

The polyimide having a structure represented by the general formula (1) contains an aromatic ring, and (i) a fluorine atom, (ii) an aliphatic ring, and (iii) a structure in which aromatic rings are linked by a sulfonyl group or an alkylene group optionally substituted with fluorine, being a polyimide containing at least one selected from the group consisting of is preferred. The polyimide having the structure represented by the general formula (1) contains at least one selected from a tetracarboxylic acid residue having an aromatic ring and a diamine residue having an aromatic ring, so that the molecular skeleton becomes rigid. Although the orientation is enhanced and the surface hardness is improved, the rigid aromatic ring skeleton tends to extend the absorption wavelength to longer wavelengths, and the transmittance in the visible light region tends to decrease.
When (i) the polyimide contains a fluorine atom, the electron state in the polyimide skeleton can be made difficult to transfer, and thus the light transmittance is improved.
When (ii) an alicyclic ring is included in the polyimide, the transmissivity of the polyimide is improved because the transfer of charges in the skeleton can be inhibited by breaking the conjugation of the π electrons in the skeleton of the polyimide.
If the polyimide contains (iii) a structure in which the aromatic rings are linked by a sulfonyl group or an alkylene group that may be substituted with fluorine, the charge transfer in the skeleton is prevented by breaking the conjugation of the π electrons in the polyimide skeleton. Light transmittance is improved from the point that it can be inhibited.

Among the polyimides having the structure represented by the general formula (1), polyimides containing fluorine atoms are preferably used from the viewpoint of improving light transmittance and surface hardness.
Regarding the content of fluorine atoms, the ratio (F/C) between the number of fluorine atoms (F) and the number of carbon atoms (C) measured on the polyimide surface by X-ray photoelectron spectroscopy is preferably 0.01 or more, Furthermore, it is preferable that it is 0.05 or more. On the other hand, if the content of fluorine atoms is too high, the inherent heat resistance of polyimide may deteriorate, so the ratio (F/C) between the number of fluorine atoms (F) and the number of carbon atoms (C) is 1 or less is preferable, and more preferably 0.8 or less.
Here, the above ratio measured by X-ray photoelectron spectroscopy (XPS) can be obtained from the atomic % value of each atom measured using an X-ray photoelectron spectrometer (for example, Thermo Scientific Theta Probe). .

In addition, since the polyimide having the structure represented by the general formula (1) has improved surface hardness, when the total of R ¹ and R ² in the general formula (1) is 100 mol%, aromatic The total amount 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 75 mol% or more. Even more preferred.

In addition, the polyimide having the structure represented by the general formula (1) does not have a tetracarboxylic acid residue of R ¹ and a silicon atom of R ² from the viewpoint of improving surface hardness and optical transparency. At least one of the diamine residues having an aliphatic ring or an aliphatic ring preferably contains an aromatic ring and a fluorine atom, and does not have a tetracarboxylic acid residue of R ¹ and a silicon atom of R ² Both diamine residues with aromatic or aliphatic rings preferably contain aromatic rings and fluorine atoms.
Polyimide having a structure represented by the general formula (1), from the viewpoint of improving surface hardness and optical transparency, when the total of R ¹ and R ² in the general formula (1) is 100 mol% , the total of the tetracarboxylic acid residue having an aromatic ring and a fluorine atom and the diamine residue having an aromatic ring and a fluorine atom is preferably 50 mol% or more, more preferably 60 mol% or more, It is even more preferably 75 mol % or more.

In addition, since the polyimide having the structure represented by the general formula (1) has improved light transmittance and tends to reduce the haze value, the tetracarboxylic acid residue of R ¹ and the silicon atom of R ² are added. It is preferable that at least one of the diamine residues having an aromatic ring or an aliphatic ring without having an aromatic ring has an aromatic ring having a perfluoroalkyl group, and furthermore, a tetracarboxylic acid residue of R ¹ and R ² of Both of the diamine residues having an aromatic ring or an aliphatic ring without silicon atoms preferably have an aromatic ring with a perfluoroalkyl group.
When the polyimide contains an aromatic ring having a perfluoroalkyl group, the compatibility between the polyimide and the ultraviolet absorber is improved, the haze value when formed into a film is easily reduced, and the properties as an optical film can be improved. can. By including an aromatic ring having a perfluoroalkyl group in the polyimide, the structure tends to be bulky and sparse (low density), the distance between the molecular chains of the polyimide resin tends to increase, and the mutual interaction between the molecular chains of the polyimide resin tends to increase. Since the action tends to decrease, the UV absorber is likely to exist in the gaps generated between the molecular chains of the polyimide resin, and the compatibility between the polyimide and the UV absorber is improved, so the haze value when formed into a film. is presumed to decrease.
Although the perfluoroalkyl group is not particularly limited, a perfluoroalkyl group having 1 to 3 carbon atoms is preferable.
Among the polyimides having the structure represented by the general formula (1), when the total of R ¹ and R ² in the general formula (1) is 100 mol%, an aromatic ring having a perfluoroalkyl group The total of the diamine residue having an aromatic ring having a tetracarboxylic acid residue and a perfluoroalkyl group is preferably 50 mol% or more, more preferably 60 mol% or more, 75 mol% or more is even more preferable.

Further, the polyimide having the structure represented by the general formula (1) is a polyimide in which 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. is preferably used from the viewpoint of improving light transmittance and improving surface hardness. The proportion of hydrogen atoms (number) directly bonded to aromatic rings in all hydrogen atoms (number) bonded to carbon atoms contained in the polyimide is preferably 60% or more, more preferably 70% or more. is preferably
If 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, even after the heating process in the atmosphere, for example, stretching at 200 ° C. or higher is preferable because there is little change in optical properties, particularly in total light transmittance and yellowness YI value. If 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 chemical structure of the polyimide changes due to low reactivity with oxygen. It is presumed that it is difficult to Utilizing its high heat resistance, polyimide film is often used in devices that require processing steps that involve heating. In the case of polyimide, which is a hydrogen atom that directly bonds, there is no need to perform these post-processes in an inert atmosphere to maintain transparency, so there is an advantage that equipment costs and atmosphere control costs can be suppressed. There is
Here, the ratio of hydrogen atoms (number) directly bonded to aromatic rings in all hydrogen atoms (number) bonded to carbon atoms contained in the polyimide is determined by high-performance liquid chromatography and gas chromatograph mass It can be determined using an analyzer and NMR. For example, the sample is decomposed with an alkaline aqueous solution or supercritical methanol, the polyimide decomposition product obtained is separated by high performance liquid chromatography, and the qualitative analysis of each separated peak is performed by gas chromatograph mass spectrometer and NMR. etc., and quantified using high-performance liquid chromatography to determine the ratio of hydrogen atoms (number) directly bonded to aromatic rings in all hydrogen atoms (number) contained in the polyimide.

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 not particularly limited, but is preferably selected appropriately according to the structure so as to exhibit a preferable glass transition temperature, which will be described later.
The average number of repeating units is usually 10 to 2,000, preferably 15 to 1,000.
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.

The polyimide used in the present invention can contain one or more polyimides having a structure represented by the general formula (1).
Moreover, 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) preferably accounts for 95% or more of the total number of repeating units of the polyimide, more preferably 98% or more, and 100% It is even more preferable to have
Structures different from the structure represented by the general formula (1) include, for example, cases in which a tetracarboxylic acid residue having no aromatic ring or aliphatic ring is included, and a polyamide structure.
Polyamide structures that may be included include, for example, polyamideimide structures containing tricarboxylic acid residues such as trimellitic anhydride, and polyamide structures containing dicarboxylic acid residues such as terephthalic acid.
The content ratio of each repeating unit in the polyimide, and the content ratio (mol %) of each tetracarboxylic acid residue and each diamine residue can be obtained from the molecular weight of the preparation when producing the polyimide. The content ratio (mol%) of each tetracarboxylic acid residue and each diamine residue in the polyimide is obtained by high performance liquid chromatography, gas chromatograph mass spectrometer, NMR, elemental It can be determined using analysis, XPS/ESCA and TOF-SIMS.

The polyimide used in the polyimide film of the present invention preferably has a weight average molecular weight of 60,000 or more, more preferably 100,000 or more, more preferably 130,000 or more, from the viewpoint of dynamic bending resistance of the polyimide film. More preferably, it is particularly preferably 160,000 or more. When the weight-average molecular weight of the polyimide is at least the lower limit, the strength of the polyimide film is improved, and deformation or breakage due to repeated bending is less likely to occur. The upper limit of the weight-average molecular weight of the polyimide used in the polyimide film of the present invention is not particularly limited, but is usually 10,000,000 or less, preferably 500,000 or less.
The weight average molecular weight of the polyimide can be measured by gel permeation chromatography (GPC) using a solution in which polyimide is dissolved. Specifically, 15 mg of polyimide powder was immersed in 15000 mg of N-methylpyrrolidone (NMP), heated to 60° C. in a water bath, and rotated at a rotation speed of 200 rpm using a stirrer until dissolution was visually confirmed. By stirring for 3 to 60 hours, an NMP solution in which polyimide is dissolved is obtained. Using the obtained NMP solution, the weight average molecular weight is measured by GPC. In GPC, the developing solvent is a 30 mmol% LiBr-NMP solution with a water content of 500 ppm or less, and a Tosoh GPC device (HLC-8120, detector: differential refractive index (RID) detector, column used: SHODEX GPC LF- 804 are connected in series), and the measurement is performed under the conditions of a sample injection amount of 50 µL, a solvent flow rate of 0.4 mL/min, a column temperature of 37°C, and a detector temperature of 37°C. The weight average molecular weight is determined based on a polystyrene standard sample having the same concentration as the sample.
As the polyimide used for the polyimide film of the present invention, a polyimide that does not dissolve in NMP is also preferable from the viewpoint of dynamic bending resistance. That is, the polyimide used in the polyimide film of the present invention is one or more selected from the group consisting of polyimides that are soluble in NMP and have a weight average molecular weight of the lower limit or more, and polyimides that are insoluble in NMP. is preferable from the viewpoint of dynamic bending resistance. Here, whether it is soluble or insoluble in NMP can be determined by dissolving the polyimide in NMP in the same manner as the method for preparing the NMP solution in the GPC measurement method described above. A polyimide that does not dissolve in a solvent can suppress a decrease in the strength of the polyimide film, and therefore tends to make it difficult for the film to deform or break due to repeated bending.

Moreover, the polyimide used in the present invention preferably has a glass transition temperature in the temperature range of 150°C or higher and 400°C or lower. When the glass transition temperature is 150° C. or higher, the heat resistance is excellent. Moreover, the glass transition temperature of 400° C. or lower enables the baking temperature to be reduced, and is preferably 380° C. or lower.
In addition, the polyimide used in the present invention preferably does not have a peak of the tan δ curve in the temperature range of −150° C. or higher and 0° C. or lower, thereby improving the surface hardness of the polyimide film at room temperature. Moreover, the polyimide used in the present invention may further have a peak of the tan δ curve in the temperature range of more than 0°C and less than 150°C.
The glass transition temperature of the polyimide used in the present invention is determined from the peak temperature of the temperature-tan δ (tan δ = loss elastic modulus (E'') / storage elastic modulus (E')) curve obtained by dynamic viscoelasticity measurement. It is a thing. The glass transition temperature of polyimide refers to the temperature of the peak at which the maximum value of the peak is maximum when there are multiple peaks in the tan δ curve. As the dynamic viscoelasticity measurement, for example, a dynamic viscoelasticity measuring device RSA III (TA Instrument Japan Co., Ltd.) is used, with a measurement range of -150 ° C. to 400 ° C., a frequency of 1 Hz, and a temperature increase. It can be done at a rate of 5°C/min. Also, the measurement can be performed with a sample width of 5 mm and a chuck-to-chuck distance of 20 mm.
In the present invention, the peak of the tan δ curve has an inflection point that is a maximum value, and the peak width between the valleys of the peak is 3 ° C. or more. Minor vertical fluctuations are not interpreted as the peak.

The content of the polyimide contained in the polyimide film used in the present invention is appropriately adjusted so as to sufficiently contain the ultraviolet absorber described later, and is not particularly limited, but from the viewpoint of bending resistance and surface hardness, 90 mass % or more, and on the other hand, it is preferably 99.9 mass % or less from the viewpoint of sufficiently containing the ultraviolet absorber and improving the weather resistance.

2. Ultraviolet Absorber The polyimide film according to the present invention contains an ultraviolet absorber having a linear or branched saturated aliphatic hydrocarbon group having 1 to 8 carbon atoms. The ultraviolet absorber is preferably contained so that the polyimide film has a transmittance of 18% or less at a wavelength of 380 nm and a transmittance of 85% or more at a wavelength of 450 nm. In addition, as the ultraviolet absorber, as long as it has a maximum absorption wavelength at a wavelength of 250 nm or more and 380 nm or less and satisfies either one of the following conditions (i) and (ii), it is generally classified as an ultraviolet absorber. It can be used regardless of what is available.
Condition (i) The absorbance at a wavelength of 380 nm is 0.005 or more, the absorbance in the visible light region of more than 380 nm and 780 nm or less is less than the absorbance at a wavelength of 380 nm, and the absorbance at a wavelength of 450 nm is 0.1 or less Condition (ii) The molar absorption coefficient at a wavelength of 380 nm is 50 or more and 500,000 or less, and the molar absorption coefficient at a wavelength of 450 nm is 10 or more and 500,000 or less. Absorbers can be dissolved in a solvent and determined using ultraviolet-visible spectroscopy (UV-vis). As a solvent for dissolving the ultraviolet absorber when determining the absorbance, a solvent capable of dissolving the ultraviolet absorber can be appropriately selected and used from among solvents in which the absorbance is not detected at a wavelength of 380 nm or more and 780 nm or less. Specifically, a solvent having an absorption wavelength on the short wavelength side in the ultraviolet region, such as acetonitrile, can be preferably used, and dimethylacetamide (DMAc) or the like may be used as appropriate. Also, the concentration when determining the absorbance is usually adjusted so that 100 ml of the solvent is used per 1 mg of the ultraviolet absorber.

Examples of the ultraviolet absorber used in the present invention include benzotriazole ultraviolet absorbers, benzophenone ultraviolet absorbers, benzoate ultraviolet absorbers, triazine ultraviolet absorbers, cyanocreate ultraviolet absorbers, and hindered amine ultraviolet absorbers. , malonic acid ester-based UV absorbers, oxalic acid anilide-based UV absorbers, etc., and commercially available products may be used.

Commercially available ultraviolet absorbers used in the present invention include, specifically, benzotriazole-based ultraviolet rays such as Sumisorb 200, Sumisorb 250, Sumisorb 300, Sumisorb 340, and Sumisorb 350 (manufactured by Sumika Chemtex Co., Ltd.). Absorbent: Benzophenones such as Sumisorb 130 (manufactured by Sumika Chemtex Co., Ltd.), Ubinal 3049 (manufactured by Ozeki Co., Ltd.), KEMIISORB 11, KEMIISORB 11S, KEMIISORB 12, and KEMIISORB 111 (manufactured by Chemipro Kasei Co., Ltd.) UV absorber: Benzoate-based UV absorber such as Sumisorb 400 (manufactured by Sumika Chemtex Co., Ltd.), KEMIISORB 112, KEMIISORB 113, KEMIISORB 114 (manufactured by Chemipro Kasei Co., Ltd.); ); cyanocreate UV absorbers such as Uvinal 3035, Uvinal 3039 and Uvinal 3030 (manufactured by Ozeki Co., Ltd.); hindered amines such as KEMISTAB 29, KEMISTAB 62, KEMISTAB 77 and KEMISTAB 94. -based UV absorbers; Malonic ester-based UV absorbers such as Hostavin PR-25 and Hostavin B-CAP (manufactured by Clariant Chemicals Co., Ltd.); An ultraviolet absorber etc. are mentioned.

The ultraviolet absorber used in the present invention is a linear or branched monovalent saturated fat having 1 to 8 carbon atoms, among others, from the viewpoint of the weather resistance of the polyimide film and the suppression of the increase in the haze value. It is preferred to have a group hydrocarbon group.

Among the UV absorbers used in the present invention, benzotriazole has good compatibility with polyimide having a structure represented by the general formula (1) and suppresses an increase in the haze value of the polyimide film. is at least one selected from UV absorbers, benzophenone UV absorbers and benzoate UV absorbers, and at least one hydrogen atom on at least one aromatic ring is a -O- bond or -CO-O- A UV absorber having a structure substituted by a linear or branched monovalent saturated aliphatic hydrocarbon group having 1 to 8 carbon atoms which may contain a bond is preferable, and among them, a benzotriazole-based UV absorber. At least one selected from UV absorbers and benzophenone-based UV absorbers is preferred.
Such preferred UV absorbers include, for example, 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl). Phenyl)-5-chlorobenzotriazole, 2-(2′-hydroxy-5′-tert-octylphenyl)benzotriazole, 2,2′-methylenebis[6-(2H-benzotriazol-2-yl)-4- tert-octylphenol], 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol, 2-(2′-hydroxy-5′-tert-butylphenyl )-2H-benzotriazole, 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol, 2-(2H-benzotriazol-2-yl)- 6-(1-methyl-1-phenylethyl)-4-(1,1,3,3,-tetramethylbutyl)phenol, 2,2′-methylenebis[4-(1,1,3,3-tetra methylbutyl)-6-(2H-benzotriazol-2-yl)phenol], 2-(3,5-di-tert-butyl-2-hydroxyphenyl)-5-chlorobenzotriazole, 2-(2H-benzo triazol-2-yl)-p-cresol, 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol, 2-benzotriazol-2-yl- 4,6-di-tert-butylphenol, 2-[5-chloro(2H)-benzotriazol-2-yl]-4-methyl-6-(tert-butyl)phenol, 2-(2H-benzotriazole-2 -yl)-4,6-di-tert-butylphenol, 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol, 2-(2H-benzo Benzotriazole UV absorbers such as triazol-2-yl)-4-methyl-6-(3,4,5,6-tetrahydrophthalimidylmethyl)phenol; 2-hydroxy-4-n-octoxybenzophenone, Benzophenone UV absorbers such as 2-hydroxy-4-methoxybenzophenone and 2,2′-dihydroxy-4,4′-dimethoxybenzophenone; 2,4-di-tert-butylphenyl 3,5-di-tert-butyl -4-hydroxybenzoe Benzoate-based UV absorbers such as hexadecyl 3,5-di-tert-butyl-4-hydroxybenzoate, 2,4-di-tert-pentylphenyl 3,5-di-tert-butyl-4-hydroxybenzoate, and hexadecyl 3,5-di-tert-butyl-4-hydroxybenzoate can be mentioned.

As the ultraviolet absorber used in the present invention, at least one selected from ultraviolet absorbers represented by the following general formula (3) and ultraviolet absorbers represented by the following general formula (4) is more preferable.

（一般式（３）及び一般式（４）において、Ｌ^１はそれぞれ独立して直接結合又は－Ｏ－結合を表し、Ｒ^２０はそれぞれ独立して、炭素数１以上８以下の直鎖状又は分岐状の１価の飽和脂肪族炭化水素基を表す。）

(In the general formulas (3) and (4), L ¹ each independently represents a direct bond or -O- bond, and R ²⁰ each independently represents a linear or represents a branched monovalent saturated aliphatic hydrocarbon group.)

In addition, the number of carbon atoms in the linear or branched saturated aliphatic hydrocarbon group having 1 to 8 carbon atoms in the ultraviolet absorber used in the present invention is the weather resistance of the polyimide film, and an increase in the haze value. From the viewpoint of suppressing, it is preferably 4 or more and 8 or less, more preferably 6 or more and 8 or less.

The UV absorber preferably has a melting point of 100° C. or higher from the standpoint of drying the solvent during production, while the melting point of the UV absorber is preferably 200° C. or lower from the standpoint of solubility.

In addition, the ultraviolet absorber has a maximum absorption wavelength at a wavelength of 250 nm or more and 380 nm or less, an absorbance at a wavelength of 380 nm of 0.005 or more, and an absorbance in the visible light region with a wavelength of more than 380 nm and 780 nm or less. It is preferably smaller than the absorbance and has an absorbance of 0.1 or less at a wavelength of 450 nm. The absorbance of the ultraviolet absorber at a wavelength of 380 nm is more preferably 0.01 or more, and even more preferably 0.02 or more. Further, the absorbance of the ultraviolet absorbent at a wavelength of 450 nm is more preferably 0.01 or less, and even more preferably 0.005 or less.

The content of the ultraviolet absorber contained in the polyimide film used in the present invention is not particularly limited, but from the viewpoint of improving weather resistance, it is preferably 0.5% by mass or more, and 1% by mass or more. It is more preferably 3% by mass or more, and on the other hand, from the viewpoint of suppressing an increase in the haze value of the polyimide film, it is preferably 15% by mass or less, and 10% by mass or less. is more preferable, and 8% by mass or less is even more preferable.

3. Additives The polyimide film of the present invention may further contain additives in addition to the polyimide and the ultraviolet absorber, if necessary. Examples of the additive include inorganic particles, a silica filler for smooth winding, and a surfactant for improving film-forming properties and defoaming properties.
When the polyimide film used in the present invention contains the additive, the content of the additive in the polyimide film is appropriately adjusted depending on the type of the additive, and is not particularly limited, but is 30% by mass or less. is preferably 10% by mass or less, and even more preferably 5% by mass or less.

4. Characteristics of Polyimide Film The polyimide film of the present invention preferably has a total light transmittance of 80% or more as measured according to JIS K7361-1. If the transmittance is high, the transparency is good, and it can be suitably used as a glass substitute material. The total light transmittance of the polyimide film of the present invention measured according to JIS K7361-1 is preferably 83% or more, more preferably 85% or more, particularly 90% or more. is preferred.
The polyimide film of the present invention preferably has a total light transmittance of 80% or more, more preferably 83% or more at a thickness of 5 μm or more and 100 μm or less, measured according to JIS K7361-1. Furthermore, it is preferably 85% or more, and particularly preferably 90% or more.
Further, the polyimide film of the present invention preferably has a total light transmittance of 80% or more, more preferably 83% or more, measured in accordance with JIS K7361-1 at a thickness of 55 μm ± 5 μm. More preferably, it is 85% or more, and particularly preferably 90% or more.
The total light transmittance measured according to JIS K7361-1 can be measured, for example, with a haze meter (eg HM150 manufactured by Murakami Color Research Laboratory). From the measured value of the total light transmittance of a certain thickness, the total light transmittance of a different thickness can be obtained as a conversion value according to Beer-Lambert's law, which can be used.

Moreover, the polyimide film of the present invention preferably has a yellowness index (YI value) of 20.0 or less calculated according to JIS K7373:2006. When the degree of yellowness is low, yellowish coloring is suppressed, light transmittance is improved, and it can be suitably used as a glass substitute material. The yellowness index (YI value) calculated according to JIS K7373:2006 is preferably 11.0 or less, more preferably 7.0 or less, and further preferably 5.0 or less. It is preferably 4.0 or less, more preferably 3.0 or less.
In the polyimide film of the present invention, the yellowness index (YI value) calculated according to JIS K7373: 2006 is preferably 20.0 or less at a thickness of 5 μm or more and 100 μm or less, and is preferably 11.0 or less. It is more preferably 7.0 or less, even more preferably 5.0 or less, particularly preferably 4.0 or less, and most preferably 3.0 or less.
Further, the polyimide film of the present invention has a yellowness index (YI value) calculated according to JIS K7373: 2006 at a thickness of 55 μm ± 5 μm, preferably 20.0 or less, and 11.0 or less. is more preferably 7.0 or less, even more preferably 5.0 or less, particularly preferably 4.0 or less, and most preferably 3.0 or less.
In addition, the polyimide film of the present invention was tested either before or after a weather resistance test conducted by irradiating for 24 hours using a UVB 313 nm lamp with an output set to 1 W/m ² /nm using a QUV weather resistance tester. Also, the yellowness index (YI value) calculated according to JIS K7373: 2006 is preferably 20.0 or less, more preferably 11.0 or less, and 7.0 or less. is more preferably 5.0 or less, particularly preferably 4.0 or less, and most preferably 3.0 or less.
In addition, the yellowness (YI value) is measured in accordance with JIS K7373: 2006 using an ultraviolet-visible-near-infrared spectrophotometer (e.g., JASCO Corporation V-7100), using a spectrophotometric method, the auxiliary illuminant C, using a 2-degree field of view, based on the transmittance measured at intervals of 1 nm in the range of 250 nm or more and 800 nm or less, tristimulus values X, Y, Z in the XYZ color system are obtained, and the X, Y, It can be calculated from the value of Z using the following formula.
YI=100(1.2769X−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 transmittance at each wavelength between 250 nm and 800 nm at intervals of 1 nm for a sample with a certain thickness. As with the light transmittance, the conversion value of each transmittance at each wavelength of different thicknesses is obtained according to Beer-Lambert's law, and it can be calculated and used based on it.

In addition, the polyimide film of the present invention suppresses yellowish coloring, improves light transmittance, and can be suitably used as a glass substitute material. The value obtained by dividing the degree (YI value) by the film thickness (μm) (YI value/film thickness (μm)) is preferably 0.60 or less, more preferably 0.25 or less, and 0.05 It is more preferably 0.04 or less, particularly preferably 0.04 or less.
In the present invention, the value obtained by dividing the yellowness index (YI value) by the film thickness (μm) (YI value/film thickness (μm)) is to the second decimal place according to rule B of JIS Z8401:1999. Rounded value.
The polyimide film of the present invention has a value (YI value/ It is preferable that the film thickness (μm) is equal to or less than the above upper limit.

In the polyimide film of the present invention, the difference in YI value (ΔYI) before and after the weather resistance test is preferably 3.0 or less, more preferably 2.5 or less, and 2.0 The following are even more preferable.

The haze value of the polyimide film of the present invention is preferably 2.0% or less, more preferably 1.5% or less, and more preferably 1.0% or less from the viewpoint of light transparency. More preferred. It is preferable that the haze value can be achieved when the thickness of the polyimide film is 5 μm or more and 100 μm or less.
In addition, the polyimide film of the present invention has a haze It is preferable that the value is equal to or less than the upper limit.
In the polyimide film of the present invention, the difference in haze value (Δhaze value) before and after the long-term reliability test is preferably 0.5% or less, more preferably 0.3% or less. It is preferably 0.2% or less, and more preferably 0.2% or less.
The haze value can be measured by a method conforming to JIS K7136:2000, for example, by a haze meter HM150 manufactured by Murakami Color Research Laboratory.

Moreover, the polyimide film of the present invention preferably has a glass transition temperature in the temperature range of 150°C or higher and 400°C or lower. The temperature range having the glass transition temperature is more preferably 200° C. or higher, still more preferably 250° C. or higher, from the viewpoint of excellent heat resistance. °C or less is more preferable.
From the viewpoint of surface hardness, the polyimide film of the present invention preferably does not have a peak of the tan δ curve in the temperature range of −150° C. or higher and 0° C. or lower.
The glass transition temperature can be measured in the same manner as the glass transition temperature of polyimide described above.

In addition, the polyimide film of the present invention has a tensile modulus of 0.8 GPa or more at 25 ° C. when measuring a 15 mm × 40 mm test piece in accordance with JIS K7127 at a tensile speed of 8 mm / min and a distance between chucks of 20 mm. From the viewpoint of dynamic bending resistance and surface hardness, it is preferably 2 GPa or less, more preferably 1.3 GPa or more and 5.0 GPa or less, and more preferably 1.8 GPa or more and 4.5 GPa or less. , 2.0 GPa or more and 4.0 GPa or less. The polyimide film of the present invention contains a specific amount of at least one divalent group selected from the above group as a diamine residue in the polyimide, so that the molecular chains are packed with each other, so when the tensile modulus is low Even if it is, it is presumed that the decrease in surface hardness can be suppressed.
The tensile modulus is measured by using a tensile tester (for example, Shimadzu Corporation: Autograph AG-X 1N, load cell: SBL-1KN), and cutting out a test piece of width 15 mm × length 40 mm from a polyimide film at 25 ° C. , 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.

Further, the polyimide film of the present invention preferably has a birefringence in the thickness direction at a wavelength of 590 nm of 0.040 or less, more preferably 0.035 or less, from the viewpoint of reducing optical distortion. It is preferably 0.030 or less, more preferably 0.025 or less, and even more preferably 0.020 or less. When the polyimide film of the present invention is used as a surface material for a display, the reduction in optical distortion of the polyimide film of the present invention can suppress deterioration of the display quality of the display. In particular, when the birefringence in the thickness direction of the polyimide film of the present invention at a wavelength of 590 nm is 0.040 or less, the polyimide film of the present invention is placed on the display surface and the display is viewed with polarized sunglasses. , is preferable from the point of being able to suppress the occurrence of iridescent unevenness. Furthermore, when the birefringence in the thickness direction of the polyimide film of the invention at a wavelength of 590 nm is 0.020 or less, the polyimide film of the invention is placed on the surface of the display and the color reproducibility is improved when the display is viewed from an angle. It is preferable from the viewpoint of improvement.
The birefringence in the thickness direction at the wavelength of 590 nm of the polyimide film of the present invention can be obtained as follows.
First, using a retardation measuring device (for example, manufactured by Oji Scientific Instruments Co., Ltd., product name "KOBRA-WR"), the thickness direction retardation value (Rth) of the polyimide film is measured at 25 ° C. and light with a wavelength of 590 nm. do. The thickness direction retardation value (Rth) is obtained by measuring the retardation value at 0-degree incidence and the retardation value at oblique 40-degree incidence, and calculating the thickness direction retardation value Rth from these retardation values. The retardation value of the oblique incidence of 40 degrees is measured by irradiating the polyimide film with light having a wavelength of 590 nm from a direction inclined by 40 degrees from the normal line of the polyimide film.
The birefringence in the thickness direction of the polyimide film can be obtained by substituting it into the formula: Rth/d. The d represents the film thickness (nm) of the polyimide film.
In addition, the thickness direction retardation value is defined by nx as the refractive index in the slow axis direction in the in-plane direction of the film (the direction in which the refractive index in the in-plane direction of the film is maximized) and the fast axis direction in the film plane (film plane Rth [nm] = {(nx + ny) / 2-nz} × d where ny is the refractive index in the direction in which the refractive index in the inner direction is the minimum, and nz is the refractive index in the thickness direction of the film. be able to.

Further, the polyimide film of the present invention preferably has an arithmetic mean roughness Ra of 10 nm or less, more preferably 5 nm or less, measured in accordance with JIS B0601 on at least one surface, and 2 nm or less. is even more preferred. When the arithmetic mean roughness Ra is equal to or less than the upper limit, it is possible to prevent deterioration of the transparency of the film, and when the polyimide film of the present invention is used as a surface material for a display, the arithmetic mean roughness Ra The visibility of the display can be improved by arranging the surface having Ra equal to or less than the upper limit so as to be on the visible side.

In the polyimide film of the present invention, the pencil hardness is preferably 3B or more, more preferably B or more, further preferably HB or more, further preferably F or more, further H or more is preferred.
The pencil hardness of the polyimide film was determined by conditioning the measurement sample for 2 hours under conditions of a temperature of 25 ° C. and a relative humidity of 60%, and then using a test pencil specified by JIS-S-6006, JIS K5600-5-4. (1999), a pencil hardness test (0.98 N load) is performed on the film surface to evaluate the highest pencil hardness that does not cause scratches. As a tester, for example, a pencil scratch coating film hardness tester manufactured by Toyo Seiki Co., Ltd. can be used.

Further, in the polyimide film of the present invention, in view of its excellent dynamic bending resistance, a dynamic bending test was performed in an environment of 25 ° C. and 50% relative humidity (RH) according to the following dynamic bending test method. The number of times until the polyimide film breaks is preferably over 800,000 times, more preferably 900,000 times or more, and even more preferably 1,000,000 times or more.
In addition, in the polyimide film of the present invention, from the viewpoint of being excellent in dynamic bending resistance in a high temperature and high humidity environment, in an environment of 60 ° C. and 93% relative humidity (RH), dynamic bending according to the following dynamic bending test method When the bending test is performed, the number of times until the polyimide film breaks is preferably over 800,000 times, more preferably 900,000 times or more, and even more preferably 1,000,000 times or more.
[Dynamic bending test method]
A test piece of polyimide film cut into a size of 20 mm × 100 mm is fixed with tape to a durability test system in a constant temperature and humidity chamber (manufactured by Yuasa System Equipment, U-shaped stretching test jig DMX-FS with no load on a planar body). . In addition, the test piece was folded at half of the long side so that the distance between both ends of the long side of the folded test piece was 6 mm, and the radius of curvature of the bent portion of the test piece was 3 mm. state. After that, bending from the flatly opened state to the folded state is regarded as one bending, and bending is repeated at 90 bending times in 1 minute until breakage, and the number of bends until the test piece breaks is measured. do.

Further, the atomic% of silicon atoms (Si) on the film surface measured by X-ray photoelectron spectroscopy of the polyimide film is preferably 0.1 atomic% or more and 10 atomic% or less, and 0.2 atomic% or more and 5 atomic% or less. More preferred.
Here, the above ratio measured by X-ray photoelectron spectroscopy (XPS) can be obtained from the atomic % value of each atom measured using an X-ray photoelectron spectrometer (for example, Thermo Scientific Theta Probe). .

In a preferred embodiment, the ratio (F/C) between the number of fluorine atoms (F) and the number of carbon atoms (C) on the surface of the polyimide film measured by X-ray photoelectron spectroscopy is 0.01 or more and 1 or less. and more preferably 0.05 or more and 0.8 or less.
In addition, the ratio (F/N) of the number of fluorine atoms (F) and the number of nitrogen atoms (N) on the surface of the polyimide film measured by X-ray photoelectron spectroscopy is preferably 0.1 or more and 20 or less. , and more preferably 0.5 or more and 15 or less.
Further, the ratio (F / Si) of the number of fluorine atoms (F) and the number of silicon atoms (Si) on the surface of the film, measured by X-ray photoelectron spectroscopy of the polyimide film, is preferably 1 or more and 50 or less. It is preferably 3 or more and 30 or less. Within these ranges, good adhesion is obtained when a functional layer such as a hard coat layer is formed on the surface of the polyimide film of the present invention.

5. Structure of Polyimide Film The thickness of the polyimide film of the present invention may be appropriately selected depending on the application, but from the viewpoint of strength, it is preferably 1 μm or more, more preferably 5 μm or more, and furthermore 10 μm or more. is preferably On the other hand, from the viewpoint of bending resistance, the thickness of the polyimide film is preferably 200 μm or less, more preferably 150 μm or less, and even more preferably 100 μm or less. If the thickness of the film is large, the difference between the inner diameter and the outer diameter when bending becomes large, and the load on the film increases, so the bending resistance tends to decrease, but the polyimide film of the present invention is used even when the thickness is large. Dynamic bending resistance can be improved, and the effect of improving dynamic bending resistance is particularly high when the thickness is 30 μm or more and 100 μm or less.

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

6. Method for producing polyimide film The method for producing the polyimide film of the present invention is not particularly limited as long as it is a method capable of producing the polyimide film of the present invention described above, but the polyimide and the ultraviolet absorber are combined. A method using a containing polyimide resin composition is preferred. According to the method using a polyimide resin composition, the decomposition of the ultraviolet absorber in the polyimide film can be suppressed, the weather resistance of the polyimide film can be improved, and the yellowness of the polyimide film (YI value) is reduced. Furthermore, it is easy to reduce the arithmetic mean roughness Ra of at least one surface of the polyimide film.

<First manufacturing method>
As a method for producing the polyimide film of the present invention using the polyimide resin composition, for example, as a first production method,
Polyimide resin containing a polyimide having a structure represented by the general formula (1), an ultraviolet absorber having a linear or branched saturated aliphatic hydrocarbon group having 1 to 8 carbon atoms, and an organic solvent A step of preparing a composition (hereinafter referred to as a polyimide resin composition preparation step);
After coating the polyimide resin composition on a support, the solvent is dried to form a polyimide resin coating film (hereinafter referred to as a polyimide resin coating film forming step).
The first manufacturing method may further include a step of stretching the polyimide resin coating (hereinafter referred to as a stretching step).
Each step of the first manufacturing method will be described in detail below.

(1) Polyimide resin composition preparation step The polyimide resin composition prepared in the first production method includes a polyimide having a structure represented by the general formula (1) and a linear chain having 1 to 8 carbon atoms Alternatively, it may contain an ultraviolet absorber having a branched saturated aliphatic hydrocarbon group, an organic solvent, and, if necessary, additives and the like.
As the polyimide having the structure represented by the general formula (1), the same polyimide as described in the polyimide film can be used. A polyimide having a structure represented by the general formula (1) can be obtained, for example, by imidating a polyimide precursor having a structure represented by the following general formula (1′).

（一般式（１’）において、Ｒ^１、Ｒ^２及びｎは、前記一般式（１）と同様である。）

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

Polyimide precursor having a structure represented by the general formula (1 '), a tetracarboxylic acid component to be the tetracarboxylic acid residue in R ¹ of the general formula (1 '), the general formula (1 ') is a polyamic acid obtained by polymerization with a diamine component that becomes a diamine residue in R ² of .
Here, R ¹ , R ² and n in the general formula (1′) can be the same as R ¹ , R ² and n in the general formula (1) explained in the polyimide.

The polyimide precursor having the structure represented by the general formula (1′) preferably has a number average molecular weight of 60,000 or more, preferably 100,000 or more, from the viewpoint of strength and dynamic bending resistance when formed into a film. is more preferably 130,000 or more, and particularly preferably 160,000 or more. On the other hand, if the number average molecular weight is too large, the viscosity becomes high, and workability such as filtration may deteriorate.
The number average molecular weight of the polyimide precursor can be determined by NMR (eg AVANCE III manufactured by BRUKER). For example, after applying the polyimide precursor solution to a glass plate and drying at 100 ° C. for 5 minutes, 10 mg of solid content is dissolved in 7.5 ml of dimethyl sulfoxide-d6 solvent, NMR measurement is performed, and it is bonded to the aromatic ring. The number average molecular weight can be calculated from the peak intensity ratio of hydrogen atoms.

Further, the polyimide precursor having the structure represented by the general formula (1′) preferably has a weight average molecular weight of 60,000 or more, preferably 100,000, from the viewpoint of strength and dynamic bending resistance when formed into a film. It is more preferably 130,000 or more, and particularly preferably 160,000 or more. On the other hand, if the weight average molecular weight is too large, the viscosity becomes high, and workability such as filtration may be lowered.
The weight average molecular weight of polyimide precursors can be measured by gel permeation chromatography (GPC).

The polyimide precursor solution is obtained by reacting the above tetracarboxylic dianhydride and the above diamine in a solvent. The solvent used for synthesizing the polyimide precursor (polyamic acid) is not particularly limited as long as it can dissolve the above-mentioned tetracarboxylic dianhydride and diamine. 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, etc. γ-butyrolactone or the like is preferably used, and among these, it is preferable to use an organic solvent containing a nitrogen atom, such as N,N-dimethylacetamide, N-methyl-2-pyrrolidone, or a combination thereof. is more preferred. In addition, an organic solvent is a solvent containing a carbon atom.

The polyimide precursor solution is prepared by combining at least two kinds of diamines, and an acid dianhydride may be added to a mixed solution of at least two kinds of diamines to synthesize polyamic acid, or at least two kinds of polyamic acids may be synthesized. may be added stepwise to the reaction solution 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 equivalents of the diamine represented by the general formula (A) is added to the reaction solution in which the diamine represented by the general formula (A) is dissolved, and the reaction is performed. to synthesize an amic acid in which the diamine represented by the general formula (A) is reacted at both ends of the acid dianhydride, all or part of the remaining diamine is added thereto, and the acid dianhydride is may be added to polymerize the polyamic acid. When polymerized by this method, the diamine represented by the general formula (A) is introduced into the polyamic acid in a linked form via one acid dianhydride.
By polymerizing the polyamic acid by such a method, the positional relationship of the amic acid having the diamine residue represented by the general formula (A) is specified to some extent, and the compatibility with the ultraviolet absorber is improved. is preferable from the viewpoint that it is easy to obtain a film having excellent bending resistance while maintaining surface hardness.

When the number of moles of diamine in the polyimide precursor solution (polyamic acid solution) is X and the number of moles of tetracarboxylic dianhydride is Y, Y/X can be 0.9 or more and 1.1 or less. It is preferably 0.95 or more and 1.05 or less, more 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 polyamic acid to be obtained can be appropriately adjusted by setting it to such a range.
The procedure of the polymerization reaction is not particularly limited, and a known method can be appropriately selected and used.

The viscosity of the polyimide precursor solution at 25° C. is preferably 500 cps or more and 200000 cps or less from the viewpoint of handleability.
In the present invention, the viscosity of the solution or composition can be measured at 25° C. using a viscometer (eg, TVE-22HT, Toki Sangyo Co., Ltd.).

In the first production method, the method for imidating the polyimide precursor having the structure represented by the general formula (1′) is preferably chemical imidization using a chemical imidization agent. When chemical imidization is performed, 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 dehydration catalysts. The acid anhydride is not limited to acetic anhydride, and includes propionic anhydride, n-butyric anhydride, benzoic anhydride, trifluoroacetic anhydride and the like, but is not particularly limited. At that time, a tertiary amine such as pyridine or β-picolinic acid may be used together. However, if these amines remain in the film, the optical properties, particularly the yellowness index (YI value), will be reduced. It is preferable to purify by reprecipitation or the like to remove components other than polyimide to 100 ppm or less based on the total weight of polyimide, and then form the film.
As the organic solvent used in the reaction liquid for chemical imidization of the polyimide precursor, for example, the same solvents as those used in the synthesis of the polyimide precursor can be used.

In the polyimide resin composition preparation step, as the organic solvent used for redissolving the polyimide having the structure represented by the general formula (1) purified from the reaction solution, the polyimide is 5% by mass or more at 25 ° C. An organic solvent having solvent solubility such that it dissolves can be appropriately selected and used, and there is no particular limitation. For example, ethylene glycol monoethyl ether, ethylene glycol monoethyl ether acetate, ethylene glycol mono-normal-butyl ether, ethylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, ortho-dichlorobenzene, xylene, cresol, chlorobenzene, isobutyl acetate, isopentyl acetate, normal-butyl acetate, normal-propyl acetate, normal-pentyl acetate, cyclohexanol, cyclohexanone, 1,4-dioxane, tetrachloroethylene, toluene, methyl isobutyl ketone, methylcyclohexanol, methylcyclohexanone, methyl-normal- Examples include butyl ketone, dichloromethane, dichloroethane and mixed solvents thereof. Among them, at least one selected from the group consisting of dichloromethane, normal-butyl acetate, propylene glycol monomethyl ether acetate and mixed solvents thereof can be preferably used.

In the polyimide resin composition preparation step, the polyimide having the structure represented by the general formula (1), after preparing a polyimide solution dissolved in the organic solvent, the polyimide solution, the ultraviolet absorber, It is preferable to prepare the polyimide resin composition by further containing an additive or the like as necessary.
The viscosity of the polyimide solution is preferably 500 cps or more and 50000 cps or less, and preferably 1000 cps or more and 10000 cps or less from the viewpoint of ease of handling and easy formation of a uniform coating film when the polyimide resin composition is formed. more preferred.
As the ultraviolet absorber and the additive, the same ones as those described for the polyimide film can be used.

The content of the polyimide having the structure represented by the general formula (1) in the total solid content of the polyimide resin composition is 70 from the viewpoint of forming a uniform coating and a polyimide film having a strength that can be handled. It is preferably at least 80% by mass, more preferably at least 80% by mass, even more preferably at least 90% by mass, and the upper limit may be appropriately adjusted depending on the components.
The content of the ultraviolet absorber in the total solid content of the polyimide resin composition is preferably 0.5% by mass or more from the viewpoint of improving the weather resistance of the polyimide film, and is 1% by mass or more. is more preferably 3% by mass or more, and on the other hand, from the viewpoint of suppressing an increase in the haze value of the polyimide film, it is preferably 15% by mass or less, and 10% by mass or less. More preferably, it is 8% by mass or less.
In addition, in this invention, solid content means all the components other than a solvent.
The content of the organic solvent in the polyimide resin composition is preferably 60% by mass or more, more preferably 70% by mass or more, from the viewpoint of forming a uniform coating film and polyimide film. % or less is preferable.

Moreover, it is preferable that the polyimide resin composition has a water content of 1000 ppm or less, since the storage stability of the polyimide resin composition is improved and the productivity can be improved.
In the present invention, the water content in the composition can be determined using a Karl Fischer moisture meter (for example, trace moisture measuring device CA-200, manufactured by Mitsubishi Chemical Corporation).
In order to reduce the moisture content to 1000 ppm or less as described above, it is preferable to dehydrate the organic solvent used or to use an organic solvent whose moisture content is controlled, and to handle it in an environment with a humidity of 5% or less.

(2) Polyimide resin coating film forming step The polyimide resin composition is applied to a support to form a polyimide resin coating film. There is no particular limitation as long as it is a certain material. For example, an inorganic material such as a glass plate, a metal plate having a mirror-finished surface, and the like can be used. The shape of the support is selected according to the coating method, and may be, for example, a plate shape, a drum shape, a belt shape, a sheet shape that can be wound around a roll, or the like.

The coating means is not particularly limited as long as it is a method capable of coating with the desired film thickness. .
Coating may be performed using a sheet-fed type coating device, or may be performed using a roll-to-roll type coating device.

In the polyimide resin coating film forming step, the method for drying the solvent is appropriately prepared according to the boiling point of the organic solvent contained in the polyimide resin composition, and is not particularly limited, but suppresses the decomposition of the ultraviolet absorber. From the point of view, it is preferable to dry at 200° C. or less.
In addition, in the polyimide resin coating film forming step, after drying the coating film until it becomes tack-free, drying the coating film at a higher temperature to further reduce the residual solvent improves the bending resistance of the polyimide film. preferred from
For example, if the boiling point of the organic solvent contained in the polyimide resin composition is less than 100 ° C., the drying conditions for drying until the polyimide resin coating film becomes tack-free are normal pressure, 30 ° C. to 80 ° C. It can be less than or it can be air dried. When the boiling point of the organic solvent contained in the polyimide resin composition is less than 100 ° C., in order to further reduce the amount of residual solvent in the polyimide resin coating, the polyimide resin coating is dried until it becomes tack-free. After that, it is preferably dried at 150° C. or higher and 200° C. or lower for preferably 60 seconds to 180 minutes, more preferably 90 seconds to 120 minutes.

The drying method of the organic solvent is not particularly limited as long as the solvent can be dried at the above temperature, but when drying by heating, for example, an oven, a drying furnace, a hot plate, infrared heating, etc. can be used. It is possible.
When the optical properties need to be highly controlled, the atmosphere during drying of the solvent is preferably 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 100 ppm or less, most preferably 50 ppm or less. Heat treatment in air may oxidize the film, resulting in discoloration and reduced performance.

(3) Stretching step The first manufacturing method may further include a step of stretching the polyimide resin coating film. By including the stretching step, the surface hardness of the polyimide film can be improved.

In the first manufacturing method, the step of stretching 101% or more and 10000% or less when the initial dimension before stretching is taken as 100% is preferably performed 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 ±50°C, 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 sufficient orientation may not be induced. On the other hand, if the stretching temperature is too high, the orientation obtained by stretching may be relaxed by the temperature, and sufficient orientation may not be obtained.

The draw ratio of the polyimide film is preferably 101% or more and 10000% or less, more preferably 101% or more and 500% or less. By stretching in the above range, the surface hardness of the obtained polyimide film can be further improved.

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

<Second manufacturing method>
As a method for producing the polyimide film of the present invention, as a second production method,
A polyimide precursor having a structure represented by the general formula (1′), an ultraviolet absorber having a linear or branched saturated aliphatic hydrocarbon group having 1 to 8 carbon atoms, and an organic solvent A step of preparing a polyimide precursor resin composition containing (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 (hereinafter referred to as a polyimide precursor resin coating film forming step);
A process for imidizing the polyimide precursor by heating (hereinafter referred to as imidization process) can also be mentioned.
The second manufacturing method is preferable because the birefringence of the polyimide film can be easily reduced.
Each step of the second manufacturing method will be described in detail below.

(1) Polyimide precursor resin composition preparation step In the polyimide precursor resin composition preparation step of the second production method, a polyimide precursor solution is produced in the polyimide resin composition preparation step of the first production method. A polyimide precursor resin composition can be prepared by adding the UV absorber and, if necessary, an additive to a polyimide precursor solution produced by a method similar to the method described above.

The content of the polyimide precursor in the total solid content of the polyimide precursor resin composition is preferably 70% by mass or more from the viewpoint of forming a uniform coating film and a polyimide film having a strength that can be handled. , more preferably 80% by mass or more, and even more preferably 90% by mass or more, and the upper limit may be appropriately adjusted depending on the components.
The content of the ultraviolet absorber in the total solid content of the polyimide precursor resin composition is preferably 0.5% by mass or more from the viewpoint of improving the weather resistance of the polyimide film, and 1% by mass or more. It is more preferably 3% by mass or more, and on the other hand, from the viewpoint of suppressing an increase in the haze value of the polyimide film, it is preferably 15% by mass or less, and 10% by mass or less. is more preferable, and 8% by mass or less is even more preferable.
The content of the organic solvent in the polyimide precursor resin composition is preferably 50% by mass or more, more preferably 60% by mass or more, from the viewpoint of forming a uniform coating film and polyimide film. Moreover, it is preferable that it is 99 mass % or less.

It is preferable that the polyimide precursor resin composition has a water content of 1000 ppm or less from the viewpoint that the storage stability of the polyimide precursor resin composition is improved and the productivity can be improved. If the polyimide precursor resin composition contains a large amount of water, the polyimide precursor may easily decompose. As a method for making the water content of the polyimide precursor resin composition 1000 ppm or less, the same method as the method of making the water content of the polyimide resin composition 1000 ppm or less in the first production method. can be done.

The viscosity of the polyimide precursor resin composition at 25° C. is preferably 500 cps or more and 200000 cps or less from the viewpoint of forming a uniform coating film and polyimide film.

(2) Polyimide precursor resin coating film forming step In the polyimide precursor resin coating film forming step in the second manufacturing method, the support and the coating method are the same as those in the polyimide resin coating film forming step in the first manufacturing method. Anything similar to that described can be used.

After applying the polyimide precursor resin composition to the support, the solvent in the coating film is dried at a temperature of 150° C. or less, preferably 30° C. to 120° C., until the coating film becomes 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, etc., but is usually 30 seconds to 240 minutes, preferably 1 minute to 180 minutes, more preferably. is preferably 90 seconds to 120 minutes. When the upper limit is exceeded, it is not preferable from the viewpoint of the production efficiency of the polyimide film. On the other hand, when it is less than the lower limit, there is a possibility that the external appearance of the resulting polyimide film may be affected by rapid drying of the solvent.

(3) Imidization step In the second manufacturing method, the polyimide precursor is imidized by heating.
In the second production method, when the stretching step is included, the imidization step may be performed on the polyimide precursor in the polyimide precursor resin coating before the stretching step, or the polyimide after the stretching step. It may be performed on the polyimide precursor in the precursor resin coating, or both the polyimide precursor in the polyimide precursor resin coating before the stretching step and the polyimide precursor present in the film after the stretching step. You can go to

The imidization temperature may be appropriately selected according to the structure of the polyimide precursor.
Generally, the temperature at which the temperature rise starts is preferably 30° C. or higher, more preferably 100° C. or higher. On the other hand, it is preferable that the heating end temperature is 250° C. or higher.

It is preferable to appropriately select the heating rate depending on the thickness of the polyimide film to be obtained. When the thickness of the polyimide film is thick, the heating rate is preferably slowed.
From the viewpoint of production efficiency of the polyimide film, the rate 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 temperature increase rate is preferable from the viewpoint of suppressing poor appearance and strength reduction of the film, controlling whitening due to imidization reaction, and improving light transmittance.

The temperature may be raised continuously or stepwise, but it is preferable to raise the temperature continuously from the viewpoints of suppressing poor appearance and strength reduction of the film and controlling whitening caused by the imidization reaction. In addition, the rate of temperature increase may be constant over the entire temperature range described above, or may be changed in the middle.

The atmosphere during the temperature rise for imidization is preferably 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. Heat treatment in air may oxidize the film, resulting in discoloration and reduced 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 the optical properties is small and an inert gas atmosphere must be used. A polyimide having high light transmittance can also be obtained.

A heating method for imidization is not particularly limited as long as the temperature can be raised to the above temperature.

Above all, it is more preferable to set the imidization ratio of the polyimide precursor to 50% or more before the stretching step. By setting the imidization rate to 50% or more before the stretching process, stretching is performed after the process, and then heating is performed at a higher temperature for a certain period of time to imidize the film. Whitening is suppressed. Among them, from the viewpoint of improving the surface hardness of the polyimide film, the imidization rate is preferably 80% or more in the imidization step before the stretching step, and the reaction is allowed to proceed to 90% or more and even 100%. is preferred. It is presumed that stretching after imidization improves the surface hardness because rigid polymer chains are easily oriented.
Incidentally, the imidization rate can be measured by spectrum analysis by infrared measurement (IR), or the like.

In order to obtain the final polyimide film, it is preferable to proceed the reaction to imidization of 90% or more, further 95% or more, furthermore 100%.
In order to allow the reaction to progress to 90% or more of imidization, and further to 100%, it is preferable to hold the heating end temperature for a certain period of time. minutes is preferred.

(4) Stretching step In the second manufacturing method, a stretching step of stretching at least one of the polyimide precursor resin coating film and the imidized coating film obtained by imidizing the polyimide precursor resin coating film. may have In the case of including the stretching step, 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 stretching step in the second production method, the method of stretching the coating film can be the same as the method explained in the stretching step in the first production method.
In the second manufacturing method, the stretching step may be performed simultaneously with the imidization step. The imidization rate is 80% or more, further 90% or more, further 95% or more, especially substantially 100% imidization. Stretching the coating film after imidization improves the surface hardness of the polyimide film. It is preferable from the point of view.

7. Use of polyimide film The use of the polyimide film of the present invention is not particularly limited, and it can be used as a member such as a base material or a surface material for which glass products such as thin plate glass have been conventionally used. The polyimide film of the present invention has excellent weather resistance, suppresses an increase in haze value after long-term storage, and has excellent dynamic bending resistance, so that it can be suitably used as a display surface material. It can be suitably used as a surface material for flexible displays, and can also be suitably used as a surface material for foldable displays.
Further, the polyimide film of the present invention is specifically, for example, a thin and bendable flexible organic EL display, mobile terminals such as smartphones and wristwatch-type terminals, display devices inside automobiles, flexible panels used for wristwatches, etc. etc. can be suitably used. Further, the polyimide film of the present invention can be used for image display device members such as liquid crystal display devices and organic EL display devices, touch panel members, flexible printed circuit boards, solar cell panel members such as surface protective films and substrate materials, and optical waveguides. It can also be applied to members, other semiconductor-related members, and the like.

II. Laminate The laminate of the present invention is a laminate comprising the polyimide film of the present invention described above and a hard coat layer containing at least one polymer of a radical polymerizable compound and a cationically polymerizable compound.

FIG. 1 shows a schematic cross-sectional view of an example of the laminate of the present invention. A laminate 10 shown in FIG. 1 has the polyimide film 1 of the present invention and a hard coat layer 2 .
Since the laminate of the present invention has the polyimide film of the present invention described above, it has excellent weather resistance, suppresses an increase in haze value after long-term storage, and has improved dynamic bending resistance. Since it has a hard coat layer, the surface hardness is further improved.

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, so the description thereof is omitted here.

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) Radically polymerizable compound A radically polymerizable compound is a compound having a radically polymerizable group. The radically polymerizable group possessed by the radically polymerizable compound is not particularly limited as long as it is a functional group capable of causing a radical polymerization reaction. Examples thereof include a group containing 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, more preferably three or more, from the viewpoint of improving the hardness of the hard coat layer.
As the radically polymerizable compound, a compound having a (meth)acryloyl group is preferable from the viewpoint of high reactivity. Compounds having two or more groups in one molecule are preferred. For example, compounds called multifunctional acrylate monomers having 2 to 6 (meth)acryloyl groups in one molecule, molecules called urethane (meth)acrylates, polyester (meth)acrylates, and epoxy (meth)acrylates Oligomers having several (meth)acryloyl groups within and having a molecular weight of several hundred to several thousand can preferably be used.
In addition, in this specification, (meth)acryloyl represents each of acryloyl and methacryloyl, and (meth)acrylate represents each of acrylate and methacrylate.

Specific examples of the radically polymerizable compound include, for example, vinyl compounds 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 (e.g., ethoxylated (ethylene oxide-modified) bisphenol A di(meth)acrylate), trimethylolpropane tri(meth)acrylate, tri Methylol ethane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol tri(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate , polyol polyacrylates such as dipentaerythritol hexa (meth) acrylate, diacrylate of bisphenol A diglycidyl ether, epoxy acrylates such as diacrylate of hexanediol diglycidyl ether, hydroxyl groups such as polyisocyanate and hydroxyethyl acrylate Urethane acrylate obtained by reaction of contained acrylate, etc. can be mentioned.

(2) Cationically polymerizable compound A cationically polymerizable compound is a compound having a cationically polymerizable group. The cationically polymerizable group of the cationically polymerizable compound is not particularly limited as long as it is a functional group capable of causing a cationic polymerization reaction. 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 cationically polymerizable groups in one molecule of the cationically polymerizable compound is preferably two or more, more preferably three or more, from the viewpoint of improving the hardness of the hard coat layer.
As the cationically polymerizable compound, among others, a compound having at least one of an epoxy group and an oxetanyl group as a cationically polymerizable group is preferable. A compound having two or more at least one oxetanyl group in one molecule is more preferable. A cyclic ether group such as an epoxy group or an oxetanyl group is preferable from the viewpoint that shrinkage accompanying a polymerization reaction is small. In addition, among the cyclic ether groups, compounds having epoxy groups are readily available in various structures, do not adversely affect the durability of the resulting hard coat layer, and are easy to control compatibility with radically polymerizable compounds. There is an advantage. In addition, among the cyclic ether groups, the oxetanyl group has a higher degree of polymerization and is less toxic than the epoxy group. There are advantages such as increasing the network formation rate obtained from the polymerizable compound and forming an independent network without leaving unreacted monomers in the film even in a region mixed with the radically polymerizable compound.

Examples of cationic polymerizable compounds having an epoxy group include polyglycidyl ethers of polyhydric alcohols having an alicyclic ring, or compounds containing cyclohexene rings or cyclopentene rings, which are treated with a suitable 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 derivatives such as alkylene oxide adducts and caprolactone adducts thereof, and glycidyl ethers produced by reaction with epichlorohydrin, and glycidyl ether type epoxy resins derived from bisphenols such as novolac epoxy resins.

The alicyclic epoxy resins include 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate (UVR-6105, UVR-6107, UVR-6110), bis-3,4-epoxycyclohexylmethyl adipate. (UVR-6128) (the trade names in parentheses are 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 glycol 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 (Denacol) 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 product names in parentheses are manufactured by Nagase ChemteX Corporation.).

Other commercially available epoxy resins include trade names of Epicoat 825, Epicote 827, Epicote 828, Epicote 828EL, Epicote 828XA, Epicote 834, Epicote 801, Epicote 801P, Epicote 802, Epicote 815, Epicote 815XA, Epicote 816A, Epikote 819, Epikote 834X90, Epikote 1001B80, Epikote 1001X70, Epikote 1001X75, Epikote 1001T75, Epikote 806, Epikote 806P, Epikote 807, Epikote 152, Epikote 154, Epikote 871, Epikote 191P, Epikote YX310, Epikote DX255, Epikote YX8000, 34 Epikote YX8000 etc. (the above are trade names, manufactured by Japan Epoxy Resin).

Examples of cationic polymerizable compounds having an oxetanyl group include 3-ethyl-3-hydroxymethyloxetane (OXT-101) and 1,4-bis-3-ethyloxetan-3-ylmethoxymethylbenzene (OXT-121). , bis-1-ethyl-3-oxetanyl methyl ether (OXT-221), 3-ethyl-3-2-ethylhexyloxymethyloxetane (OXT-212), 3-ethyl-3-phenoxymethyloxetane (OXT- 211) (the product names in parentheses are those of Toagosei Co., Ltd.), and the product names of Etanacol EHO, Etanacol OXBP, Etanacol OXTP, and Etanacol OXMA (all of these are product names of 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, the radically polymerizable compound and the cationically polymerizable compound. It can be obtained by adding a polymerization initiator to at least one of them, if necessary, and carrying out a polymerization reaction by a known method.

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

Any radical polymerization initiator may be used as long as it can release a substance that initiates radical polymerization by at least one of light irradiation and heating. Examples of photoradical polymerization initiators include imidazole derivatives, bisimidazole derivatives, N-arylglycine derivatives, organic azide compounds, titanocenes, aluminate complexes, organic peroxides, N-alkoxypyridinium salts, thioxanthone derivatives and the like. 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.) ), 1-hydroxy-cyclohexyl-phenyl-ketone (trade name Irgacure 184, manufactured by Ciba Japan Co., Ltd.), 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butane-1- On (trade name Irgacure 369, manufactured by 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, manufactured by Ciba Japan Co., Ltd.), but 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 Co., Ltd. 、イルガキュアＯＸＥ０１、ＤＡＲＯＣＵＲ ＴＰＯ、ＤＡＲＯＣＵＲ１１７３、日本シイベルヘグナー（株）製のＳｐｅｅｄｃｕｒｅＭＢＢ、ＳｐｅｅｄｃｕｒｅＰＢＺ、ＳｐｅｅｄｃｕｒｅＩＴＸ、ＳｐｅｅｄｃｕｒｅＣＴＸ、ＳｐｅｅｄｃｕｒｅＥＤＢ、Ｅｓａｃｕｒｅ ＯＮＥ、Ｅｓａｃｕｒｅ ＫＩＰ１５０、Ｅｓａｃｕｒｅ ＫＴＯ４６、日本化薬（株）製のＫＡＹＡＣＵＲＥ ＤＥＴＸ－Ｓ、ＫＡＹＡＣＵＲＥ ＣＴＸ , KAYACURE BMS, KAYACURE DMBI, and the like.

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

Examples of radical polymerization initiators and cationic polymerization initiators include aromatic iodonium salts, aromatic sulfonium salts, aromatic diazonium salts, aromatic phosphonium salts, triazine compounds, iron arene complexes, and the like. More specifically, iodonium chlorides, bromides, borofluorides, hexafluorophosphate salts, hexafluoro Iodonium salts such as antimonate salts, sulfonium chlorides such as triphenylsulfonium, 4-tert-butyltriphenylsulfonium, tris(4-methylphenyl)sulfonium, bromides, borofluorides, hexafluorophosphate salts, hexafluoroantimonates sulfonium salts such as salts, 2,4,6-tris(trichloromethyl)-1,3,5-triazine, 2-phenyl-4,6-bis(trichloromethyl)-1,3,5-triazine, 2- Examples include, but are not limited to, 2,4,6-substituted-1,3,5-triazine compounds such as methyl-4,6-bis(trichloromethyl)-1,3,5-triazine. .

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

3. Structure of Laminate The laminate of the present invention is not particularly limited as long as it has the polyimide film and the hard coat layer, and as shown in FIG. A hard coat layer may be laminated, or the hard coat layer may be laminated on both sides of the polyimide film. Further, the laminate of the present invention includes, in addition to the polyimide film and the hard coat layer, for example, a layer for improving adhesion between the polyimide film and the hard coat layer, as long as the effects of the present invention are not impaired. It may have other layers such as a primer layer. Further, in the laminate of the present invention, the polyimide film and the hard coat layer may be positioned adjacent to each other.

The total thickness of the laminate of the present invention may be appropriately selected depending on the application, but from the viewpoint of strength, it is preferably 10 μm or more, more preferably 40 μm or more. On the other hand, from the viewpoint of bending resistance, the thickness is preferably 300 μm or less, more preferably 250 μm or less.
In addition, 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. From the viewpoint of curl prevention, hard coat layers may be formed on both sides of the polyimide film.

4. Characteristics of Laminate In the laminate of the present invention, the hard coat layer side surface preferably has a pencil hardness of H or more, more preferably 2H or more, and 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 9.8N.

The laminate of the present invention preferably has a total light transmittance measured in accordance with JIS K7361-1 of 80% or more, more preferably 83% or more, and further preferably 85% or more. Preferably, it is more preferably 90% or more. Since the transmittance is high in this way, the transparency is good, and it can be used as a substitute 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 index (YI value) calculated according to JIS K7373: 2006 of preferably 30 or less, more preferably 20 or less, and more preferably 15 or less. More preferably, it is particularly preferably 10 or less.
The yellowness index (YI value) of the laminate of the present invention can be measured in the same manner as the yellowness index (YI value) of the polyimide film calculated according to JIS K7373:2006.

The haze value of the laminate of the present invention is preferably 10% or less, more preferably 8% or less, and even more preferably 5% or less from the viewpoint of light transmittance.
The haze value of the laminate of the present invention can be measured in the same manner as the haze value of the polyimide film.

The birefringence in the thickness direction of the laminate of the present invention at a wavelength of 590 nm is preferably 0.040 or less, preferably 0.035 or less, further preferably 0.030 or less, and more It is preferably 0.020 or less.
The birefringence of the laminate of the present invention can be measured in the same manner as the birefringence of the polyimide film in the thickness direction at a wavelength of 590 nm.

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

6. Method for manufacturing a laminate As a method for manufacturing a laminate of the present invention, for example,
a step of forming a coating film of a composition for forming a hard coat layer containing at least one of a radically polymerizable compound and a cationic 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 radically polymerizable compound, the cationic polymerizable compound, the polymerization initiator and the additive contained in the composition for forming the hard coat layer may be the same as those described for the hard coat layer. , the solvent can be appropriately selected from known solvents and used.

As a method for 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 is applied to at least one surface of the polyimide film by a known method. A method of coating with a coating means may be mentioned.
The coating means is not particularly limited as long as it is a method capable of coating with the desired film thickness, and examples thereof include the same means as those for coating the polyimide resin composition on the support.

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

According to the polymerizable groups of the radically polymerizable compound and the cationically polymerizable compound contained in the curable resin composition, the curable resin composition for the hard coat layer is applied and, if necessary, dried. , By curing the coating film by at least one of light irradiation and heating, a hard coat layer containing at least one polymer of a radically 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 beams such as ultra-high pressure mercury lamps, high pressure mercury lamps, low pressure mercury lamps, carbon arcs, xenon arcs and metal halide lamps are used. The irradiation amount of the energy beam source is about 50 to 5000 mJ/cm ² as an integrated exposure amount at an ultraviolet wavelength of 365 nm.
When heating, it is usually treated at a temperature of 40° C. or higher and 120° C. or lower. Alternatively, the reaction may be carried out by allowing to stand at room temperature (25° C.) for 24 hours or longer.

III. Display Surface Material The display surface material of the present invention is the aforementioned polyimide film of the present invention or the laminate of the present invention.

The display surface material of the present invention is used by arranging it so as to be positioned on the surface of various displays. The display surface material of the present invention, like the polyimide film of the present invention and the laminate of the present invention described above, has excellent weather resistance, suppresses an increase in haze value after long-term storage, and has excellent dynamic bending resistance. It can be used particularly suitably for flexible displays.

The display surface material of the present invention can be used for various known displays, and is not particularly limited, but can be used, for example, for the displays described in the use of the polyimide film of the present invention.

When the display surface material of the present invention is the laminate of the present invention, the surface that becomes the outermost surface after being placed on the surface of the display may be the surface on the side of the polyimide film, or the hard coat layer. It may be the surface of the side. Above all, it is preferable to dispose the surface material for a display of the present invention so that the surface on the hard coat layer side faces the front side. Further, the display surface material of the present invention may have an anti-fingerprint layer on the outermost surface.

The method of disposing the surface material for display of the present invention on the surface of the display is not particularly limited, but an example thereof includes a method of interposing an adhesive layer. As the adhesive layer, a conventionally known adhesive layer that can be used for adhesion of surface materials for displays can be used.

IV. 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 having a plurality of conductive parts disposed on one surface side of the polyimide film or the laminate;
and a plurality of extraction lines electrically connected to at least one side of the end of the conductive portion.

Since 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, it has excellent weather resistance, suppresses an increase in haze value after long-term storage, and It has excellent resistance and can be used particularly suitably for flexible displays.
The touch panel member of the present invention is not particularly limited, but preferably includes a laminate having hard coat layers on both sides of the polyimide film of the present invention in terms of surface hardness.
Moreover, 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 of the present invention.
The touch panel member of the present invention can be used, for example, by arranging it so as to be positioned on the surface of various displays. Also, the touch panel member of the present invention and the laminate of the present invention as a surface material can be arranged in this order on the surface of various displays.

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. 4 is a schematic plan view of FIG. and FIG. 4 is an AA′ cross-sectional view of the touch panel member shown in FIG. The touch panel member 20 shown in FIGS. 2, 3 and 4 is arranged in contact with the laminate 10 having the hard coat layers 2a and 2b on both sides of the polyimide film 1 of the present invention and one surface of the laminate 10. A first transparent electrode 4 and a second transparent electrode 5 arranged in contact with the other surface of the laminate 10 are provided. In the first transparent electrode 4, a plurality of first conductive portions 41, which are strip-shaped electrode pieces extending in the x-axis direction, are arranged at predetermined intervals. A first lead-out line 7 electrically connected to the first conductive portion 41 is connected to the first conductive portion 41 at one of its longitudinal ends. A first terminal 71 for electrical connection with an external circuit is preferably provided at the end of the first lead-out line 7 extending to the edge 21 of the laminate 10 . The first conductive portion 41 and the first lead-out line 7 are generally connected within the non-active area 23 located outside the active area 22 visible to the user of the touch panel.
For the connection between the first conductive portion 41 and the first lead-out line 7, for example, as shown in FIG. Specifically, the connection portion 24 can be formed by extending a layer of conductive material from the longitudinal end portion of the first conductive portion 41 to a predetermined position within the non-active area 23 . Furthermore, by overlapping at least a portion of the first lead-out line 7 on the connection part 24, a connection structure between the first conductive part 41 and the first lead-out line 7 can be formed.
The connection between the first conductive portion 41 and the first lead-out line 7 is not limited to the structure forming the connecting portion 24 as shown in FIG. For example, although not shown, the longitudinal end portion of the first conductive portion 41 is extended to the non-active area 23, and within the non-active area 23, the first conductive portion 41 is extended to the non-active area 23. Both may be electrically connected by running the first lead-out line 7 on the end of the .
Note that FIG. 2 shows a mode in which one of the longitudinal ends of the first conductive portion 41 is connected to the first lead-out line 7, but in the present invention, one first conductive portion is provided. A configuration may be adopted in which the first extraction lines 7 are electrically connected to both ends of the portion 41 in the longitudinal direction.

As shown in FIG. 3 , the touch panel member 20 includes a second transparent electrode 5 arranged in contact with the other surface of the laminate 10 . In the second transparent electrode 5, second conductive portions 51, which are a plurality of strip-shaped electrode pieces extending in the y-axis direction, are arranged at predetermined intervals in the x-axis direction. there is
A second lead-out line 8 electrically connected to the second conductive portion 51 is connected to the second conductive portion 51 at one of its longitudinal ends.
The second lead-out line 8 extends to a position where it does not overlap the first terminal 71 at the edge 21 of the laminate 10 from which the first lead-out line 7 extends. .
A second terminal 81 for electrical connection with an external circuit is preferably provided at the end of the second lead-out line 8 extending to the edge 21 of the laminate 10 .
For the electrical connection between the second conductive portion 51 and the second lead-out line 8, the same form as the electrical connection between the first lead-out line 7 and the first conductive portion 41 can be applied. .

The pattern in which the first lead-out line 7 is a long wire and the second lead-out line 8 is a short wire, as shown in FIGS. 2 and 3, is merely an embodiment of the touch panel member of the present invention. For example, it is possible to adopt 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 extending direction of the first lead-out line 7 and the extending direction of the second lead-out line 8 are not limited to the directions shown in FIGS. 2 and 3, and can be arbitrarily designed.

The conductive part provided in the touch panel member of the present invention can be applied by appropriately selecting the one that constitutes the transparent electrode in the touch panel member, and the pattern of the conductive part is not limited to those shown in FIGS. For example, it is possible to appropriately select and apply a transparent electrode pattern capable of detecting a change in electric capacitance due to contact or close contact with a finger, etc., by a capacitance method.
The material of the conductive portion is preferably a light-transmitting material, for example, an indium oxide-based transparent electrode material mainly composed of indium tin oxide (ITO), indium oxide, indium zinc oxide (IZO), or the like. , tin oxide (SnO ₂ ), zinc oxide (ZnO), etc., and conductive polymer compounds such as polyaniline and polyacetylene. Also, the first conductive portion 41 and the second conductive portion 51 may be formed using the same conductive material, or may be formed using different materials. In particular, forming the first conductive portion 41 and the second conductive portion 51 using the same type of conductive material is preferable from the viewpoint of more effectively suppressing the occurrence of warpage and distortion of the touch panel member.
The thickness of the conductive portion is not particularly limited, but when the conductive portion is formed by photolithography, it can generally be formed to a thickness of about 10 nm to 500 nm.

It does not matter whether or not the conductive material that constitutes the extraction line included in the touch panel member of the present invention is light transmissive. In general, the extraction line can be formed using a highly conductive metal material such as silver or copper. Specific examples include simple metals, composites of metals, composites of metals and metal compounds, and metal alloys. Examples of simple metals include simple substances of silver, copper, gold, chromium, platinum, and aluminum. Examples of metal composites include MAM (three-layer structure of molybdenum, aluminum, and molybdenum). A laminate of chromium oxide and chromium can be exemplified as a composite of a metal and a metal compound. Silver alloys and copper alloys are commonly used as metal alloys. Moreover, APC (alloy of silver, palladium, and copper) etc. can be illustrated as a metal alloy. Further, in the lead-out line, a suitable resin component may be mixed with the metal material described above.
In the touch panel member of the present invention, the terminals provided at the ends of the lead-out lines can be made of the same material as the lead-out lines, for example.
The thickness and width of the lead-out line are not particularly limited, but when the lead-out line is formed by photolithography, it is generally formed to have a thickness of about 10 nm to 1000 nm and a width of 5 μm to 5 μm. It is formed to have a thickness of about 200 μm. On the other hand, when the lead-out line is formed by printing such as screen printing, it is generally formed with a thickness of about 5 μm to 20 μm and a width of 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. For example, the first transparent electrode and the second transparent electrode are laminated on separate laminates. can be anything.
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 has the laminate 10 of the present invention and the first transparent electrode 4 arranged in contact with one surface of the laminate 10, and the first conductive member 201 The transparent electrode 4 has a plurality of first conductive parts 41 . A second conductive member 202 shown in FIG. 6 has a laminate 10′ of the present invention and a 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 showing another example of the touch panel member of the present invention. A touch panel member 20' shown in FIG. 7 includes a first conductive member 201 shown in FIG. and a conductive member 202 . In the touch panel member 20′, the surface of the first conductive member 201 which does not have the first transparent electrode 4 and the surface of the second conductive member 202 which has the transparent electrode 5 are connected via the adhesive layer 6. are pasted together. In the present invention, for example, an adhesive layer for adhering the laminate of the present invention and the touch panel member of the present invention, an adhesive layer for adhering the touch panel members of the present invention, and the touch panel member of the present invention and the display device. As the adhesive layer for adhering, etc., conventionally known adhesive layers used for optical members can be appropriately selected and used. In the conductive member used for the touch panel member of the present invention, the configuration and materials of the transparent electrodes, lead lines and terminals may be the same as those of the transparent electrodes, lead lines and terminals used for the touch panel member of the present invention described above. can.

V. Liquid crystal display device The liquid crystal 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,
a liquid crystal display section having a liquid crystal layer between opposing substrates arranged on one side of the polyimide film or the laminate.

Since the liquid crystal display device of the present invention includes the polyimide film of the present invention or the laminate of the present invention described above, it has excellent weather resistance, suppresses an increase in haze value after long-term storage, and can be repeatedly bent. It has excellent resistance to bending when bending, and can be particularly preferably used as a flexible display.
From the viewpoint of surface hardness, the liquid crystal display device of the present invention preferably includes a laminate having hard coat layers on both sides of the polyimide film of the present invention.
Further, the liquid crystal display device of the present invention may include the touch panel member of the present invention described above.
Moreover, the counter substrate of the liquid crystal display device of the present invention may be provided with the polyimide film of the present invention or the laminate of the present invention.

FIG. 8 is a schematic cross-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 a laminate 10 having a hard coat layer 2 on one side of the polyimide film 1 of the present invention and a laminate having hard coat layers 2a and 2b on both sides of the polyimide film 1 of the present invention. It has a touch panel member 20 having a first transparent electrode 4 on one side of the body 10 ′ and a second transparent electrode 5 on the other side, and a liquid crystal display section 30 . In the liquid crystal display device 100 , the layered body 10 is used as a surface material, and the layered body 10 and the touch panel member 20 are bonded together with the adhesive layer 6 interposed therebetween.

The liquid crystal display portion used in the liquid crystal display device of the present invention has a liquid crystal layer formed between substrates arranged opposite to each other, and may employ a configuration used in conventionally known liquid crystal display devices. 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 liquid crystal display devices can be adopted. etc. can be mentioned.
The counter substrate used in the liquid crystal display device of the present invention can be appropriately selected and used according to the driving method of the liquid crystal display device, etc., and the one provided with 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 mixtures thereof can be used depending on the driving method of the liquid crystal display device of the present invention.
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 the liquid crystal layer is formed by the above method, the liquid crystal cell is gradually cooled to room temperature, thereby aligning the enclosed liquid crystal.
The liquid crystal display device of the present invention may further have colored layers of a plurality of colors and a light-shielding portion defining pixels between the opposing substrates. Further, the liquid crystal display section may have a backlight section having a light-emitting element and a fluorescent material on the outside of the opposing substrates, on the opposite side of the touch panel member. Polarizing plates may be provided on the outer surfaces of the opposing substrates.

FIG. 9 is a schematic cross-sectional view showing another example of the liquid crystal display device of the present invention. A liquid crystal display device 200 shown in FIG. 9 includes a laminate 10 having a hard coat layer 2 on one side of the polyimide film 1 of the present invention and a laminate having hard coat layers 2a and 2b on both sides of the polyimide film 1 of the present invention. A first conductive member 201 having a first transparent electrode 4 on one side of the body 10' and one side of a laminate 10'' having hard coat layers 2a and 2b on both sides of the polyimide film 1 of the present invention. and a liquid crystal display section 30. In the liquid crystal display device 200, the laminate 10 and the first conductive member 201 , and the first conductive member 201 and the second conductive member 202 are bonded together via the adhesive layer 6. The configuration of the touch panel member 20′ is, for example, the touch panel member 20 shown in FIG. The conductive member used in the liquid crystal display device of the present invention may be the same as the conductive member used in the touch panel member of the present invention, for example.

VI. Organic electroluminescence display device The organic electroluminescence display device of the present invention comprises the polyimide film of the present invention described above or the laminate of the present invention described above,
and an organic electroluminescence display section having an organic electroluminescence layer between opposing substrates arranged on one side of the polyimide film or the laminate.

Since the organic electroluminescence display device of the present invention includes the polyimide film of the present invention or the laminate of the present invention described above, it has excellent weather resistance, suppresses an increase in haze value after long-term storage, and can be repeatedly bent. It is excellent in bending resistance when folded, and can be particularly preferably used as a flexible display.
From the viewpoint of surface hardness, the organic electroluminescence display device of the present invention preferably comprises a laminate having hard coat layers on both sides of the polyimide film of the present invention.
Moreover, the organic electroluminescence display device of the present invention may be provided with the above-described touch panel member of the present invention.
Moreover, the counter substrate of the organic electroluminescence display device of the present invention may comprise the polyimide film of the present invention or the laminate of the present invention.

FIG. 10 is a schematic cross-sectional view showing an example of the organic electroluminescence display device of the present invention. The organic electroluminescence display device 300 shown in FIG. 10 includes a laminate 10 having a hard coat layer 2 on one side of the polyimide film 1 of the present invention, and hard coat layers 2a and 2b on both sides of the polyimide film 1 of the present invention. A touch panel member 20 having a first transparent electrode 4 on one surface of a laminate 10 ′ and a second transparent electrode 5 on the other surface, and an organic electroluminescence display section 40 . In the organic electroluminescence display device 300 , the layered body 10 is used as a surface material, and the layered body 10 and the touch panel member 20 are bonded together with the adhesive layer 6 interposed therebetween.

The organic electroluminescence display portion (organic EL display portion) used in the organic electroluminescence display device (organic EL display device) of the present invention includes an organic electroluminescence layer (organic EL layer) formed between substrates arranged opposite to each other. , and a configuration used in conventionally known organic EL display devices can be adopted.
The organic EL display section 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, a hole injection layer, a hole transport layer, an organic EL light-emitting layer, an electron transport layer and an electron injection A material having a structure in which layers are laminated 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 counter 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, etc., and the one provided with the laminate of the present invention may be used.

FIG. 11 is a schematic cross-sectional view showing another example of the organic electroluminescence display device of the present invention. The organic electroluminescence display device 400 shown in FIG. 11 comprises a laminate 10 having a hard coat layer 2 on one side of the polyimide film 1 of the present invention, and hard coat layers 2a and 2b on both sides of the polyimide film 1 of the present invention. A first conductive member 201 having a first transparent electrode 4 on one surface of the laminate 10' having and an organic electroluminescence display section 40. In the organic electroluminescence display device 400, the laminate 10 and the second One conductive member 201, the first conductive member 201, and the second conductive member 202 are bonded together via an adhesive layer 6. The structure of the touch panel member 20' is shown in FIG. The configuration of the touch panel member 20' can be the same as that shown in 1. As the conductive member used in the organic electroluminescence display device of the present invention, for example, the same conductive member as used in the touch panel member of the present invention can be used. can be used.

Hereinafter, measurement or evaluation was performed at 25° C. unless otherwise specified.
[Evaluation method]
<Weight average molecular weight of polyimide>
The weight average molecular weight of polyimide is determined by immersing 15 mg of polyimide powder in 15000 mg of N-methylpyrrolidone (NMP), heating it to 60 ° C. in a water bath, and using a stirrer at a rotation speed of 200 rpm to visually confirm dissolution. An NMP solution with a concentration of 0.1% by weight was obtained by stirring for 3 to 60 hours until the mixture was warmed up. The solution is filtered through a syringe filter (pore size: 0.45 μm), a 30 mmol% LiBr-NMP solution with a water content of 500 ppm or less is used as a developing solvent, and a GPC device (manufactured by Tosoh, HLC-8120, detector: differential Refractive index (RID) detector, column used: 2 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. Measurement was performed under the conditions of The weight-average molecular weight of the polyimide was measured using a polystyrene standard sample with the same concentration as the sample (weight-average molecular weight: 364,700, 204,000, 103,500, 44,360, 27,500, 13,030, 6,300, 3, 070) was converted to standard polystyrene. The elution time was compared with the calibration curve to obtain the weight average molecular weight.
<Viscosity of polyimide solution>
The viscosity of the polyimide solution was measured using a viscometer (eg, TVE-22HT, Toki Sangyo Co., Ltd.) at 25° C. with a sample volume of 0.8 ml.

<Film thickness measurement method>
The thickness of the polyimide film test piece cut into a size of 10 cm × 10 cm was measured at a total of 5 points, the four corners and the center, using a digital linear gauge (manufactured by Ozaki Seisakusho Co., Ltd., model PDN12 digital gauge). was taken as the film thickness of the polyimide film.

<Total light transmittance>
The total light transmittance was measured according to JIS K7361-1 with a haze meter (HM150, manufactured by Murakami Color Research Laboratory).

<Birefringence>
Using a retardation measuring device (manufactured by Oji Scientific Instruments Co., Ltd., product name “KOBRA-WR”), the thickness direction retardation value (Rth) of the polyimide film was measured at 25° C. with light having a wavelength of 590 nm. For the thickness direction retardation value (Rth), the retardation value at 0-degree incidence and the retardation value at oblique 40-degree incidence were measured, and the thickness direction retardation value Rth was calculated from these retardation values. The retardation value of the oblique incidence of 40 degrees was measured by irradiating the polyimide film with light having a wavelength of 590 nm from a direction inclined by 40 degrees from the normal line of the polyimide film.
The birefringence of the polyimide film was obtained by substituting it into the formula: Rth/d (film thickness (nm) of polyimide film).

<Tensile modulus>
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. , the tensile modulus at 25° C. was measured. A tensile tester (manufactured by Shimadzu Corporation: Autograph AG-X 1N, load cell: SBL-1KN) was used.

<Pencil hardness>
The pencil hardness is measured by conditioning the measurement sample for 2 hours under conditions of a temperature of 25 ° C. and a relative humidity of 60%, and then using a test pencil specified by JIS-S-6006. Using a hardness tester, a pencil hardness test (0.98 N load) specified in JIS K5600-5-4 (1999) was performed on the film surface to evaluate the highest pencil hardness that does not cause scratches.

<Arithmetic mean roughness Ra>
The surface of the side not in contact with the substrate (glass plate) during film production of the polyimide film was observed in tapping mode using an atomic force microscope (AFM) (manufactured by Bruker, MultiMode 8 HR), and JIS B0601: 2013. The arithmetic average roughness Ra was obtained by observing a 10 μm square visual field four times, and the average value thereof was taken as the arithmetic average roughness Ra of the polyimide film. .

<Dynamic bending test>
A test piece of polyimide film cut into a size of 20 mm × 100 mm was fixed with tape to a durability test system in a constant temperature and humidity chamber (manufactured by Yuasa System Equipment, U-shaped stretching test jig DMX-FS with no load on a planar body). . In addition, the test piece was folded at half of the long side so that the distance between both ends of the long side of the folded test piece was 6 mm, and the radius of curvature of the bent portion of the test piece was 3 mm. set the state. After that, under an environment of 25 ° C. and 50% relative humidity (RH), bending from the flatly opened state to the folded state is regarded as one bending, and bending is performed 90 times per minute until it breaks. was repeated, and the number of times of bending until the test piece broke was measured.

<Haze value>
The haze value of the polyimide film was measured immediately after the production of the polyimide film and after the long-term reliability test described below. Also, the Δhaze value was calculated by subtracting the haze value immediately after the production of the polyimide film from the haze value after the long-term reliability test described below. The haze value of the polyimide film was measured using a haze meter (HM150, manufactured by Murakami Color Research Laboratory) in accordance with JIS K7136:2000.
(Long-term reliability test)
The polyimide film was placed in an environment of 70° C.±2° C. using a hot air circulating heating device and allowed to stand for 240 hours.

<YI value (yellowness)>
Immediately after the production of the polyimide film and after the following weather resistance test, the YI value of the polyimide film was determined, and ΔYI was calculated by subtracting the YI value immediately after the production of the polyimide film from the YI value after the weather resistance test.
In addition, the YI value is measured by a spectrophotometric method using an ultraviolet-visible-near-infrared spectrophotometer (JASCO Corporation V-7100) in accordance with JIS K7373:2006. Tristimulus values X, Y, Z in the XYZ color system are obtained based on the transmittance measured at intervals of 1 nm in the range of 250 nm or more and 800 nm or less, and from the values of X, Y, Z, the following Calculated from the formula.
YI=100(1.2769X−1.0592Z)/Y
(Weather resistance test)
A test piece cut out of a polyimide film to 55 mm × 75 mm is used with a QUV weather resistance tester (QUV Accelerated Weathering Tester manufactured by Q-LAB) with an output set to 1 W / m ² / nm, using a UVB 313 nm lamp. A weatherability test was performed by irradiating for 24 hours.

(Synthesis Examples 1 to 6, Comparative Synthesis Example 1)
A polyimide was synthesized using the diamine and acid dianhydride described in Table 1, and the resulting polyimide was dissolved in dichloromethane so as to have the viscosity described in Table 1, and polyimide solutions 1 to 6 and comparative polyimide solution 1. got Table 1 shows the weight average molecular weight of each polyimide measured by GPC. As a specific example of the method for synthesizing polyimide, the method for synthesizing polyimide 2 used in polyimide solution 2 will be described below.
A solution of dehydrated N,N-dimethylacetamide (2903 g) and 1,3-bis(3-aminopropyl)tetramethyldisiloxane (AprTMOS) (15.9 g) dissolved in a 5 L separable flask. 4,4'-(Hexafluoroisopropylidene)diphthalic anhydride (6FDA) (14.6 g) was added to the liquid temperature controlled at 30°C so that the temperature rise was 2°C or less. and stirred with a mechanical stirrer for 30 minutes. 2,2′-Bis(trifluoromethyl)benzidine (TFMB) (387 g) was added thereto, and after confirming that it was completely dissolved, 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 solution (solid content: 25% by mass) in which the polyimide precursor was dissolved. The molar ratio of TFMB to AprTMOS (TFMB:AprTMOS) used in the polyimide precursor was 95:5.
In a nitrogen atmosphere, the polyimide precursor solution (400 g) cooled to room temperature was added to a 5 L separable flask. Dehydrated dimethylacetamide (109 g) was added thereto and stirred until uniform. Next, pyridine (41.4 g) and acetic anhydride (53.4 g) as catalysts were added and stirred at room temperature for 24 hours to synthesize a polyimide solution. Butyl acetate (406 g) was added to the resulting polyimide solution and stirred until uniform, and then methanol (902 g) was gradually added to obtain a slightly turbid solution. Methanol (2105 g) was added at once to the turbid solution to obtain a white slurry. The slurry was filtered and washed with methanol five times to obtain polyimide 2 (91 g).

Abbreviations in the table are as follows.
TFMB: 2,2′-bis(trifluoromethyl)benzidine AprTMOS: 1,3-bis(3-aminopropyl)tetramethyldisiloxane 6FDA: 4,4′-(hexafluoroisopropylidene)diphthalic anhydride

(Synthesis Examples 7-13)
In the procedure for synthesizing polyimide 2, instead of 2,2'-bis(trifluoromethyl)benzidine (TFMB), diamine 1 listed in Table 2 was used to synthesize each polyimide, and the polyimides listed in Table 2 were used. Polyimide solutions 7 to 13 were obtained by dissolving the obtained polyimide in dichloromethane so as to obtain a viscosity.

(Examples 1 to 6, Comparative Example 1)
To the polyimide solutions 1 to 6 obtained in Synthesis Examples 1 to 6, Comparative Synthesis Example 1, and Comparative Polyimide Solution 1, an ultraviolet absorber represented by the following chemical formula (1) (Sumisorb 130, Sumika Chemtex Co., Ltd.) was blended in an amount of 5% by mass in the solid content to obtain a polyimide resin composition.
Using the resulting polyimide resin composition, the following procedures (i) to (iii) were performed to prepare polyimide films having the thicknesses shown in Table 3.
(i) A polyimide resin composition was applied onto a glass plate, dried naturally, and then the film was peeled off from the glass plate.
(ii) The film was dried in a circulating oven at 50°C for 10 minutes.
(iii) The film was heated to 200°C at a heating rate of 10°C/min under a nitrogen stream (oxygen concentration of 100 ppm or less), held at 200°C for 1 hour, and then cooled to room temperature to obtain a polyimide film. .

(Examples 7 to 12, Comparative Example 2)
To the polyimide solutions 1 to 6 obtained in Synthesis Examples 1 to 6, Comparative Synthesis Example 1, and Comparative Polyimide Solution 1, an ultraviolet absorber represented by the following chemical formula (2) (Sumisorb 340, Sumika Chemtex Co., Ltd.) was blended in an amount of 5% by mass in the solid content to obtain a polyimide resin composition.
A polyimide film having a thickness shown in Table 4 was produced by performing the procedures (i) to (iii) using the obtained polyimide resin composition.

(Examples 13-19)
In the polyimide solutions 7 to 13 obtained in Synthesis Examples 7 to 13, an ultraviolet absorber represented by the chemical formula (2) (Sumisorb 340, manufactured by Sumika Chemtex Co., Ltd.) is added as an ultraviolet absorber in the solid content. was blended in an amount of 5% by mass to obtain a polyimide resin composition.
A polyimide film having a thickness shown in Table 5 was produced by performing the procedures (i) to (iii) using the obtained polyimide resin composition.

(Comparative Examples 3-9)
In Examples 1 to 6 and Comparative Example 1, except that the polyimide resin composition was not blended with an ultraviolet absorber, in the same manner as in Examples 1 to 6 and Comparative Example 1, a polyimide film having a thickness shown in Table 6. was made.

Each polyimide film obtained in Examples 1 to 19 and Comparative Examples 1 to 9 was evaluated using the evaluation method described above. The evaluation results are shown in Tables 3-6.

Comparison between Examples 1 to 6 described in Table 3 and Comparative Example 1, comparison between Examples 7 to 12 described in Table 4 and Comparative Example 2, and Examples 1 to 12 described in Tables 3 and 4 From the comparison with Comparative Examples 3 to 9 shown in Table 6, the polyimide films of Examples 1 to 12 corresponding to the polyimide film of the present invention are polyimide having a structure represented by the general formula (1), By containing in combination with an ultraviolet absorber having a linear or branched saturated aliphatic hydrocarbon group having 1 to 8 carbon atoms, while having excellent weather resistance, haze value after long-term storage The rise was suppressed, indicating that the resin film had improved dynamic bending resistance. In addition, the polyimide films of Examples 1 to 12 had good light transmittance and had optical properties that could be used as surface materials for displays. In addition, the polyimide films of Examples 1 to 12 had a sufficiently small arithmetic mean roughness Ra on at least one surface, and suppressed deterioration of visibility when used as a display surface material.
Furthermore, from the comparison between Examples 1 to 3 and Examples 4 to 6 described in Table 3, and the comparison between Examples 7 to 9 and Examples 10 to 12 described in Table 4, the polyimide film contains the In the polyimide having a structure represented by the general formula (1), 2.5 mol% or more and less than 10 mol% of the total amount of R ² is the diamine represented by the general formula (A) except for two amino groups. It was found that the lower residue is more inhibited from lowering the surface hardness.

Further, from Table 5, the polyimide films of Examples 13 to 19, which correspond to the polyimide films of the present invention, also have excellent weather resistance, while suppressing the increase in haze value after long-term storage, and have dynamic bending resistance. It has been shown that it has excellent light transmittance, has a sufficiently small arithmetic mean roughness Ra on at least one surface, and suppresses a decrease in visibility when used as a surface material for a display. Among them, the polyimide films of Examples 13 to 18 were more inhibited from lowering the surface hardness than the polyimide film of Example 19. As a result, in the polyimide having the structure represented by the general formula (1) contained in the polyimide film, among R ² , the residue obtained by removing two amino groups from the diamine represented by the general formula (A) are diamine residues having no silicon atoms and having aromatic or aliphatic rings, and more than ^{half of said remaining R 2 are} 1,4-cyclohexanediamine residues, trans-1,4-bismethylenecyclohexanediamine residues, 4,4′-diaminodiphenylsulfone residues, 3,4′-diaminodiphenylsulfone residues, 2,2-bis(4-aminophenyl)propane at least one divalent group selected from the group consisting of residues, 2,2-bis(4-aminophenyl)hexafluoropropane residues, and divalent groups represented by the general formula (2) It has become clear that the decrease in surface hardness is further suppressed when there is

Furthermore, the polyimide films obtained in Examples 1 to 6 were subjected to the dynamic bending test in an environment of 60 ° C. and 93% RH. It was superior in dynamic bending resistance compared to the polyimide film of As a result, in the polyimide having the structure represented by the general formula (1) contained in the polyimide film, 2.5 mol% or more and less than 10 mol% of the total amount of R ² is represented by the general formula (A) It was clarified that a residue obtained by removing two amino groups from the diamine from which the compound is formed suppresses a decrease in dynamic bending resistance in a high-temperature, high-humidity environment.

REFERENCE SIGNS LIST 1 polyimide film 2, 2a, 2b hard coat layer 10, 10′, 10″ laminate 4 first transparent electrode 41 first conductive portion 5 second transparent electrode 51 second conductive portion 6 adhesive layer 7 first lead-out line 71 first terminal 8 second lead-out line 81 second terminal 20, 20' touch panel member 21 edge of laminate 22 active area 23 non-active area 24 connection portion 201 first conductive member 202 second Second conductive member 30 liquid crystal display section 40 organic electroluminescence display section 100, 200 liquid crystal display device 300, 400 organic electroluminescence display device

Claims (13)

A polyimide having a structure represented by the following general formula (1);
At least one selected from an ultraviolet absorber represented by the following general formula (3) and an ultraviolet absorber represented by the following general formula (4) ,
A polyimide film having a total light transmittance of 80% or more as measured according to JIS K7361-1.

(In 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, and R ^2.5 mol% or more and 50 mol% or less of the total amount of R ² is a residue obtained by removing two amino groups from the diamine represented by the following general formula (A), and 50 mol% or more of the total amount of R 2 97 0.5 mol % or less is a diamine residue having no silicon atom and having an aromatic ring or an aliphatic ring.n represents the number of repeating units.)

(In the general formula (A), each L independently represents a direct bond or -O- bond, each R ¹⁰ independently represents a linear or branched monovalent monovalent represents a saturated aliphatic hydrocarbon group, each R ¹¹ independently represents a linear or branched divalent saturated aliphatic hydrocarbon group having 1 to 8 carbon atoms, k is a number from 0 to 200; A plurality of L, R ¹⁰ and R ¹¹ may be the same or different.)

(In the general formulas (3) and (4), L ¹ each independently represents a direct bond or -O- bond, and R ²⁰ each independently represents a linear or represents a branched monovalent saturated aliphatic hydrocarbon group.) In the polyimide having a structure represented by the general formula (1), 2.5 mol% or more and less than 10 mol% of the total amount of R ² is two amino groups from the diamine represented by the general formula (A). and the remaining R ² are diamine residues having no silicon atoms and having an aromatic or aliphatic ring, and more than half of said remaining R ² are 1 ,4-cyclohexanediamine residue, trans-1,4-bismethylenecyclohexanediamine residue, 4,4′-diaminodiphenylsulfone residue, 3,4′-diaminodiphenylsulfone residue, 2,2-bis(4 -Aminophenyl)propane residue, 2,2-bis(4-aminophenyl)hexafluoropropane residue, and at least one selected from the group consisting of a divalent group represented by the following general formula (2) The polyimide film according to claim 1 , which is a divalent group.

(In general formula (2), R ³ and R ⁴ each independently represent a hydrogen atom, an alkyl group, or a perfluoroalkyl group.) The polyimide film according to claim 1 or 2 , wherein k in the general formula (A) is 0 or 1 in the diamine represented by the general formula (A). The yellowness calculated in accordance with JIS K7373: 2006 is 20.0 or less,
The haze value measured in accordance with JIS K7136:2000 is 2.0% or less,
The birefringence in the thickness direction at a wavelength of 590 nm is 0.040 or less,
The polyimide film according to any one of claims 1 to 3 . 5. The polyimide film according to any one of claims 1 to 4 , wherein at least one surface has an arithmetic mean roughness Ra of 10 nm or less as measured according to JIS B0601. In the polyimide having a structure represented by the general formula (1), R ¹ in the general formula (1) is a cyclohexanetetracarboxylic dianhydride residue, a cyclopentanetetracarboxylic dianhydride residue, a di Cyclohexane-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 anhydride residue, 3, 4′-(hexafluoroisopropylidene)diphthalic anhydride residue, 3,3′-(hexafluoroisopropylidene)diphthalic anhydride residue, 4,4′-oxydiphthalic anhydride residue, and 3, 6. The polyimide film according to any one of claims 1 to 5 , which is at least one tetravalent group selected from the group consisting of 4'-oxydiphthalic anhydride residues. A laminate comprising the polyimide film according to any one of claims 1 to 6 and a hard coat layer containing at least one polymer of a radical polymerizable compound and a cationically polymerizable compound. The radically polymerizable compound is a compound having two or more (meth)acryloyl groups in one molecule, and the cationically polymerizable compound is a compound having two or more at least one of an epoxy group and an oxetanyl group in one molecule. A laminate according to claim 7 , wherein: A surface material for a display, which is the polyimide film according to any one of claims 1 to 6 or the laminate according to claim 7 or 8 . The display surface material according to claim 9 , which is for flexible displays. The polyimide film according to any one of claims 1 to 6 , or the laminate according to claim 7 or 8 ,
A transparent electrode having a plurality of conductive parts disposed on one surface side of the polyimide film or the laminate;
A touch panel member comprising: a plurality of take-out lines electrically connected on 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 7 or 8 ,
a liquid crystal display portion having a liquid crystal layer between opposing substrates arranged on one surface side of the polyimide film or the laminate;
A liquid crystal display device having The polyimide film according to any one of claims 1 to 6 , or the laminate according to claim 7 or 8 ,
an organic electroluminescence display portion having an organic electroluminescence layer between opposing substrates arranged on one side of the polyimide film or the laminate;
An organic electroluminescence display device having

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