JP2022011501A - Polyimide precursor resin, manufacturing method of polyimide film, manufacturing method of laminate, polyimide film, laminate, member for display, member for touch panel, liquid crystal display unit and organic electroluminescent display unit - Google Patents

Abstract

To provide a manufacturing method of a polyimide film capable of inhibiting a deterioration of a flexure resistance and further reducing a phase difference while securing sufficient transparency.SOLUTION: A manufacturing method of a polyimide film includes a step of imidization by heating using a polyimide precursor resin composition containing a polyimide precursor resin including a general formula (1-1) or a general formula (1-2), in which 95.0% or more with regard to all R included the general formula (1-1) and the general formula (1-2) is a 1-10C alkyl group, and weight average molecular weight in terms of polystyrene by gel permeation chromatography is 108,000 or more. (Each symbol in the formula is as stated in the description.)SELECTED DRAWING: None

Description

The present invention relates to a polyimide precursor resin, a method for producing a polyimide film using the polyimide precursor resin, a method for producing a laminate, a polyimide film, a laminate, a display member, a touch panel member, a liquid crystal display device, and an organic electroluminescence. It is related to the display device.

While thin flat glass is excellent in hardness, heat resistance, etc., it is difficult to bend, easily breaks when dropped, has problems in workability, and is heavier than plastic products. For this reason, in recent years, resin products such as resin base materials and resin films are being replaced with glass products from the viewpoint of workability and weight reduction, and research on resin products that can be used as glass substitute products has been conducted.

For example, with the rapid progress of displays such as liquid crystals and organic EL and electronics such as touch panels, it has become necessary to make devices thinner, lighter, and more flexible. Conventionally, various electronic elements such as thin transistors and transparent electrodes are formed on a thin plate glass in these devices, but by changing the thin plate glass to a resin film, the impact resistance of the panel itself is enhanced. , Flexible, thinner and lighter.

As a resin material that can replace glass, for example, polyimide is being studied. In general, polyimide is colored yellow or brown, so it is difficult to use it in fields where transparency is required, such as display applications and optical applications, but polyimides with improved transparency have been studied.
As the polyimide with improved transparency, for example, a polyimide obtained by polymerizing 4,4'-(hexafluoroisopropylidene) diphthalic acid anhydride and 4,4'-diamino-2,2'-bis (trifluoromethyl) biphenyl. Is known (for example, Patent Document 1).
Further, Patent Document 2 describes that the tetracarboxylic acid dianhydride having a specific structure has excellent transparency, high heat resistance and a low coefficient of linear thermal expansion, and exhibits solvent processability with a low hygroscopic solvent. A polyimide obtained by polymerizing 4,4'-diamino-2,2'-bis (trifluoromethyl) biphenyl is disclosed.

Japanese Unexamined Patent Publication No. 4-288331 International Publication No. 2014/046180

Resin products that can be used as glass substitutes are required to have low optical strain in addition to high elastic modulus because of not only transparency but also surface hardness and impact resistance.
However, in a polyimide film, a component that imparts a high elastic modulus tends to be easily colored and tends to have a low transparency, and a component that is difficult to color and imparts a high transparency tends to have a low elastic modulus. High transparency was a trade-off characteristic relationship. Further, the conventional polyimide film has a problem that the optical distortion is large, and the phase difference in the film thickness direction is particularly large.
Furthermore, mobile devices with foldable screens should be in a folded state when carried and in an unfolded state when used. Therefore, it is required that the flexible display mounted on the mobile device does not cause display defects even if it is repeatedly bent, and the base material and surface material for the flexible display are resistant to bending when repeatedly bent (hereinafter referred to as "bending resistance"). , Sometimes referred to as dynamic flexion resistance) is required.
The polyimide films described in Patent Documents 1 and 2 have sufficient transparency and a relatively good elastic modulus, but have a problem that optical strain is large and a phase difference in the film thickness direction is particularly large. Therefore, there has been a demand for a method for producing a polyimide film that suppresses a decrease in bending resistance and further reduces a phase difference.
Further, there has been a demand for a film that simultaneously satisfies transparency, low phase difference, high elastic modulus, and good bending resistance.

The present invention has been made in view of the above problems, and provides a method for producing a polyimide film which has sufficient transparency, suppresses a decrease in bending resistance, and further reduces a phase difference. The first purpose. Another object of the present invention is to provide a polyimide precursor resin used in the method for producing a polyimide film, and a method for producing a laminate using the method for producing the polyimide film.
Further, the present invention has been made in view of the above problems, and a polyimide film and a laminate having a low phase difference, a high elastic modulus, and improved bending resistance while having sufficient transparency are provided. The second purpose is to provide. Another object of the present invention is to provide a display member which is the polyimide film or the laminate, and a touch panel member, a liquid crystal display device, and an organic electroluminescence display device provided with the polyimide film or the laminate. do.

The first invention for solving the first object is the following general formula (1-1) or the following general formula (1-2).

（一般式（１－１）及び（１－２）において、Ａは、下記グループＡ１及び下記グループＡ２からなる群から選択される少なくとも１種のテトラカルボン酸二無水物の残基である４価の基を表し、Ｂは下記グループＢ１及び下記グループＢ２からなる群から選択される少なくとも１種のジアミンの残基である２価の基を表し、Ｒは水素原子又は炭素数１～１０のアルキル基を表す。）で表される構成単位を有し、
＜グループＡ１：４，４’－（ヘキサフルオロイソプロピリデン）ジフタル酸二無水物、４，４’－オキシジフタル酸二無水物、シクロブタンテトラカルボン酸二無水物、及び下記化学式（ａ－１）で表される酸二無水物＞

(In the general formulas (1-1) and (1-2), A is a tetravalent residue of at least one tetracarboxylic acid dianhydride selected from the group consisting of the following groups A1 and the following groups A2. B represents a divalent group which is a residue of at least one diamine selected from the group consisting of the following group B1 and the following group B2, and R represents a hydrogen atom or an alkyl having 1 to 10 carbon atoms. It has a structural unit represented by () and is represented by a group.
<Group A1: 4,4'-(hexafluoroisopropyridene) diphthalic acid dianhydride, 4,4'-oxydiphthalic acid dianhydride, cyclobutanetetracarboxylic acid dianhydride, and the following chemical formula (a-1). Acid dianhydride>

＜グループＡ２：ピロメリット酸二無水物、３，３’，４，４’－ビフェニルテトラカルボン酸二無水物、及びｐ－フェニレンビス（トリメリテート無水物）＞
＜グループＢ１：２，２’－ビス（トリフルオロメチル）ベンジジン、４，４’－ジアミノジフェニルエーテル、ビス（４－アミノフェニル）スルホン、及びビス［４－（４－アミノフェノキシ）フェニル］スルホン＞
＜グループＢ２：フェニレンジアミン、４－アミノ安息香酸４－アミノフェニル、ビス（４－アミノフェニル）テレフタレート、４，４’－ジアミノベンズアニリド、及びＮ，Ｎ’－ビス（４－アミノフェニル）テレフタルアミド＞
前記一般式（１－１）及び（１－２）において、前記グループＡ１からなる群から選択される少なくとも１種のテトラカルボン酸二無水物の残基であるＡ、及び、前記グループＢ１からなる群から選択される少なくとも１種のジアミンの残基であるＢの少なくとも一方を含有し、
前記一般式（１－１）及び（１－２）中に含まれる全てのＲに対する９５．０％以上が炭素数１～１０のアルキル基であり、
更に、下記一般式（２）

<Group A2: pyromellitic acid dianhydride, 3,3', 4,4'-biphenyltetracarboxylic dianhydride, and p-phenylenebis (trimeritate anhydride)>
<Group B1: 2,2'-bis (trifluoromethyl) benzidine, 4,4'-diaminodiphenyl ether, bis (4-aminophenyl) sulfone, and bis [4- (4-aminophenoxy) phenyl] sulfone>
<Group B2: Phenylene diamine, 4-aminophenyl 4-aminobenzoic acid, bis (4-aminophenyl) terephthalate, 4,4'-diaminobenzanilide, and N, N'-bis (4-aminophenyl) terephthalamide. ＞
In the general formulas (1-1) and (1-2), it consists of A which is a residue of at least one tetracarboxylic dianhydride selected from the group consisting of the group A1 and the group B1. Containing at least one of B, which is a residue of at least one diamine selected from the group,
95.0% or more of all R contained in the general formulas (1-1) and (1-2) are alkyl groups having 1 to 10 carbon atoms.
Furthermore, the following general formula (2)

{一般式（２）において、Ｘは下記式（ｘ１）～（ｘ４）

{In the general formula (2), X is the following formulas (x1) to (x4).

（式（ｘ３）において、Ｌは、－Ｏ－、－Ｓ－、－ＣＨ_２－、－ＣＨ（ＣＨ_３）－、－Ｃ（ＣＨ_３）_２－、－Ｃ（ＣＦ_３）_２－、又は－ＣＯ－を表し、＊は結合手を表す。）で表される構造からなる群から選択される少なくとも１つの２価の基を表し、Ｂは前記グループＢ１及び前記グループＢ２からなる群から選択される少なくとも１種のジアミンの残基である２価の基を表す。}で表される構成単位を有していてもよく、
ゲル浸透クロマトグラフィーのポリスチレン換算による重量平均分子量が１０８，０００以上である、ポリイミド前駆体樹脂を提供する。

(In equation (x3), L is -O-, -S-, -CH _2- , -CH (CH ₃ )-, -C (CH ₃ ) _2- , -C (CF ₃ ) _2- , or. -CO-, * represents at least one divalent group selected from the group consisting of the structures represented by), and B represents the group consisting of the group B1 and the group B2. Represents a divalent group that is a residue of at least one diamine to be made. } May have a structural unit represented by
Provided is a polyimide precursor resin having a weight average molecular weight of 108,000 or more in terms of polystyrene in gel permeation chromatography.

In the polyimide precursor resin according to the first embodiment of the present invention, in the general formulas (1-1) and (1-2), A is 4,4'-(hexafluoroisopropyridene) diphthalic acid anhydride. A tetravalent residue of at least one tetracarboxylic acid dianhydride selected from the group consisting of a substance, a cyclobutane tetracarboxylic acid dianhydride, and an acid dianhydride represented by the chemical formula (a-1). It is preferable to represent the group of the above from the viewpoint of transparency and imparting solubility.

In the polyimide precursor resin according to the first embodiment of the present invention, in the general formulas (1-1) and (1-2), B is the residue of 2,2'-bis (trifluoromethyl) benzidine. It is preferable to represent a divalent group which is a group from the viewpoint of imparting transparency.

The first invention also comprises a step of preparing a polyimide precursor resin composition containing the polyimide precursor resin according to the first embodiment of the present invention and an organic solvent.
A step of applying the polyimide precursor resin composition to a support to form a polyimide precursor resin coating film, and a step of forming the polyimide precursor resin coating film.
Provided is a method for producing a polyimide film, which comprises a step of imidizing the polyimide precursor resin by heating the polyimide precursor resin coating film.

Further, the first invention relates to a step of manufacturing a polyimide film by the method of manufacturing a polyimide film according to the first embodiment of the present invention.
A step of applying a composition for a hard coat layer containing at least one of a radically polymerizable compound and a cationically polymerizable compound to at least one surface of the polyimide film to form a coating film for forming a hard coat layer.
A method for producing a laminate including a step of forming a hard coat layer containing at least one polymer of a radically polymerizable compound and a cationically polymerizable compound by curing the coating film for forming a hard coat layer. offer.

The second invention for solving the second object is described in the following general formula (1').

（一般式（１’）において、Ａは、下記グループＡ１及び下記グループＡ２からなる群から選択される少なくとも１種のテトラカルボン酸二無水物の残基である４価の基を表し、Ｂは下記グループＢ１及び下記グループＢ２からなる群から選択される少なくとも１種のジアミンの残基である２価の基を表す。）で表される構成単位を有し、
＜グループＡ１：４，４’－（ヘキサフルオロイソプロピリデン）ジフタル酸二無水物、４，４’－オキシジフタル酸二無水物、シクロブタンテトラカルボン酸二無水物、及び下記化学式（ａ－１）で表される酸二無水物＞

(In the general formula (1'), A represents a tetravalent group which is a residue of at least one tetracarboxylic acid dianhydride selected from the group consisting of the following groups A1 and the following groups A2, and B is. It has a structural unit represented by (representing a divalent group which is a residue of at least one diamine selected from the group consisting of the following group B1 and the following group B2).
<Group A1: 4,4'-(hexafluoroisopropyridene) diphthalic acid dianhydride, 4,4'-oxydiphthalic acid dianhydride, cyclobutanetetracarboxylic acid dianhydride, and the following chemical formula (a-1). Acid dianhydride>

＜グループＡ２：ピロメリット酸二無水物、３，３’，４，４’－ビフェニルテトラカルボン酸ニ無水物、及びｐ－フェニレンビス（トリメリテート無水物）＞
＜グループＢ１：２，２’－ビス（トリフルオロメチル）ベンジジン、４，４’－ジアミノジフェニルエーテル、ビス（４－アミノフェニル）スルホン、及びビス［４－（４－アニノフェノキシ）フェニル］スルホン＞
＜グループＢ２：フェニレンジアミン、４－アミノ安息香酸４－アミノフェニル、ビス（４－アミノフェニル）テレフタレート、４，４’－ジアミノベンズアニリド、及びＮ，Ｎ’－ビス（４－アミノフェニル）テレフタルアミド＞
前記一般式（１’）において、Ａは、少なくとも前記化学式（ａ－１）で表される酸二無水物の残基である４価の基を含有し、
更に、下記一般式（２）

<Group A2: pyromellitic dianhydride, 3,3', 4,4'-biphenyltetracarboxylic dianhydride, and p-phenylenebis (trimeritate anhydride)>
<Group B1: 2,2'-bis (trifluoromethyl) benzidine, 4,4'-diaminodiphenyl ether, bis (4-aminophenyl) sulfone, and bis [4- (4-aninophenoxy) phenyl] sulfone>
<Group B2: Phenylene diamine, 4-aminophenyl 4-aminobenzoic acid, bis (4-aminophenyl) terephthalate, 4,4'-diaminobenzanilide, and N, N'-bis (4-aminophenyl) terephthalamide. ＞
In the general formula (1'), A contains at least a tetravalent group which is a residue of the acid dianhydride represented by the chemical formula (a-1).
Furthermore, the following general formula (2)

{一般式（２）において、Ｘは下記式（ｘ１）～（ｘ４）

{In the general formula (2), X is the following formulas (x1) to (x4).

（式（ｘ３）において、Ｌは、－Ｏ－、－Ｓ－、－ＣＨ_２－、－ＣＨ（ＣＨ_３）－、－Ｃ（ＣＨ_３）_２－、－Ｃ（ＣＦ_３）_２－、又は－ＣＯ－を表し、＊は結合手を表す。）で表される構造からなる群から選択される少なくとも１つの２価の基を表し、Ｂは前記グループＢ１及び前記グループＢ２からなる群から選択される少なくとも１種のジアミンの残基である２価の基を表す。}で表される構成単位を有していてもよいポリイミド樹脂を含有し、
ＪＩＳ Ｋ７３６１－１に準拠して測定する全光線透過率が、膜厚４０μｍの換算値で８５．０％以上であり、ＪＩＳ Ｋ７３７３－２００６に準拠して算出される黄色度を膜厚（μｍ）で除した値が、０．１５未満であり、
波長５９０ｎｍにおける厚み方向の複屈折率が、０．０２５未満であり、
１０ｍｍ×１５０ｍｍの試験片を、ＪＩＳ Ｋ７１２７に準拠し、引張り速度を５０ｍｍ／分、チャック間距離を１００ｍｍとして、２５℃で測定する引張試験における引張弾性率が４．０ＧＰａ以上であり、且つ、下記動的屈曲試験において、屈曲回数が、１０万回以上である、ポリイミドフィルムを提供する。
（動的屈曲試験）
２０ｍｍ×１００ｍｍの試験片を、長辺の半分の位置で湾曲させて、平行に配置した金属板で挟み、両側の金属板間の距離が６０ｍｍから２．５ｍｍとなるように２５℃、６０％相対湿度（ＲＨ）の環境下で、１分間に９０回の屈曲回数で繰り返し変化させ、試験片の屈曲を繰り返す。

(In equation (x3), L is -O-, -S-, -CH _2- , -CH (CH ₃ )-, -C (CH ₃ ) _2- , -C (CF ₃ ) _2- , or. -CO-, * represents at least one divalent group selected from the group consisting of the structures represented by), and B represents the group consisting of the group B1 and the group B2. Represents a divalent group that is a residue of at least one diamine to be made. Contains a polyimide resin that may have a structural unit represented by }.
The total light transmittance measured according to JIS K7361-1 is 85.0% or more in terms of the film thickness of 40 μm, and the yellowness calculated according to JIS K7373-2006 is the film thickness (μm). The value divided by is less than 0.15,
The birefringence in the thickness direction at a wavelength of 590 nm is less than 0.025.
A test piece of 10 mm × 150 mm has a tensile elastic modulus of 4.0 GPa or more in a tensile test measured at 25 ° C., with a tensile speed of 50 mm / min and a distance between chucks of 100 mm, in accordance with JIS K7127, and is as follows. Provided is a polyimide film having a bending frequency of 100,000 times or more in a dynamic bending test.
(Dynamic bending test)
A 20 mm × 100 mm test piece is curved at the half position of the long side, sandwiched between metal plates arranged in parallel, and 25 ° C., 60% so that the distance between the metal plates on both sides is 60 mm to 2.5 mm. In a relative humidity (RH) environment, the test piece is repeatedly bent 90 times per minute.

Further, the second invention has a polyimide film according to one embodiment of the second invention and a hard coat layer containing at least one polymer of a radically polymerizable compound and a cationically polymerizable compound. , Provide a laminate.

The second invention also provides a display member which is the polyimide film of the second invention or the laminate of the second invention.

Further, the second invention is the polyimide film according to the second embodiment of the present invention, or the laminate according to the second embodiment of the present invention.
A transparent electrode composed of a plurality of conductive portions arranged on one surface side of the polyimide film or the laminated body, and the like.
Provided is a touch panel member having a plurality of take-out wires electrically connected on at least one side of an end portion of the conductive portion.

Further, the second invention is the polyimide film according to the second embodiment of the present invention, or the laminate according to the second embodiment of the present invention.
Provided is a liquid crystal display device having the polyimide film or a liquid crystal display unit having a liquid crystal layer between facing substrates arranged on one surface side of the laminated body.

Further, the second invention is the polyimide film according to the second embodiment of the present invention, or the laminate according to the second embodiment of the present invention.
Provided is an organic electroluminescence display device having an organic electroluminescence display unit having an organic electroluminescence layer between facing substrates arranged on one surface side of the polyimide film or the laminate.

According to the first aspect of the present invention, it is possible to provide a method for producing a polyimide film which has sufficient transparency, suppresses a decrease in bending resistance, and further reduces a phase difference. In addition, the first invention can provide a polyimide precursor resin used in the method for producing a polyimide film and a method for producing a laminate using the method for producing a polyimide film.
Further, according to the second invention, it is possible to provide a polyimide film and a laminate having a low phase difference, a high elastic modulus, and improved bending resistance while having sufficient transparency. Further, according to the second invention, there is provided a display member which is the polyimide film or the laminate, a touch panel member provided with the polyimide film or the laminate, a liquid crystal display device, and an organic electroluminescence display device. can do.

It is a figure for demonstrating the method of a dynamic bending test. It is a schematic plan view of one surface of an example of the touch panel member of this invention. It is a schematic plan view of the other side of the touch panel member shown in FIG. 2 is a cross-sectional view taken along the line AA'of the touch panel member shown in FIGS. 2 and 3. It is a schematic plan view which shows an example of the conductive member provided with the laminated body of this invention. It is a schematic plan view which shows another example of the conductive member provided with the laminated body of this invention. It is a schematic sectional drawing which shows another example of the touch panel member of this invention. It is a schematic sectional drawing which shows an example of the liquid crystal display device of this invention. It is a schematic sectional drawing which shows another example of the liquid crystal display device of this invention. It is a schematic sectional drawing which shows an example of the organic electroluminescence display device of this invention. It is schematic cross-sectional view which shows another example of the organic electroluminescence display device of this invention.

Hereinafter, the polyimide precursor resin according to the present invention, the method for producing a polyimide film, the method for producing a laminate, the second polyimide film according to the present invention, a laminate, a display member, a touch panel member, a liquid crystal display device, and the like. And the organic polyimide display device will be described in detail.
In addition, the terms such as "parallel", "orthogonal", and "identical" and the values of length and angle, etc., which specify the shape and geometric conditions and their degrees as used in the present specification, are strictly referred to. Without being bound by the meaning, we will interpret it including the range where similar functions can be expected.
Further, in the present specification, (meth) acrylic represents each of acrylic and methacrylic.
Further, in the present specification, "light" means active light or radiation, and for example, the emission line spectrum of a mercury lamp, far ultraviolet rays typified by an excimer laser, extreme ultraviolet rays (EUV light), X-rays, electron beams and the like. It is included.
Further, in the drawings attached to the present specification, the scale, the aspect ratio, and the like may be appropriately changed from those of the actual product and exaggerated for the convenience of illustration and comprehension.
Further, in the present specification, "-" indicating a numerical range is used in the sense that the numerical values described before and after the numerical range are included as the lower limit value and the upper limit value.

I. Polyimide precursor resin The polyimide precursor resin according to the first embodiment of the present invention has the following general formula (1-1) or the following general formula (1-2).

（一般式（１－１）及び（１－２）において、Ａは、下記グループＡ１及び下記グループＡ２からなる群から選択される少なくとも１種のテトラカルボン酸二無水物の残基である４価の基を表し、Ｂは下記グループＢ１及び下記グループＢ２からなる群から選択される少なくとも１種のジアミンの残基である２価の基を表し、Ｒは水素原子又は炭素数１～１０のアルキル基を表す。）で表される構成単位を有し、
＜グループＡ１：４，４’－（ヘキサフルオロイソプロピリデン）ジフタル酸二無水物、４，４’－オキシジフタル酸二無水物、シクロブタンテトラカルボン酸二無水物、及び下記化学式（ａ－１）で表される酸二無水物＞

(In the general formulas (1-1) and (1-2), A is a tetravalent residue of at least one tetracarboxylic acid dianhydride selected from the group consisting of the following groups A1 and the following groups A2. B represents a divalent group which is a residue of at least one diamine selected from the group consisting of the following group B1 and the following group B2, and R represents a hydrogen atom or an alkyl having 1 to 10 carbon atoms. It has a structural unit represented by () and is represented by a group.
<Group A1: 4,4'-(hexafluoroisopropyridene) diphthalic acid dianhydride, 4,4'-oxydiphthalic acid dianhydride, cyclobutanetetracarboxylic acid dianhydride, and the following chemical formula (a-1). Acid dianhydride>

＜グループＡ２：ピロメリット酸二無水物、３，３’，４，４’－ビフェニルテトラカルボン酸二無水物、及びｐ－フェニレンビス（トリメリテート無水物）＞
＜グループＢ１：２，２’－ビス（トリフルオロメチル）ベンジジン、４，４’－ジアミノジフェニルエーテル、ビス（４－アミノフェニル）スルホン、及びビス［４－（４－アミノフェノキシ）フェニル］スルホン＞
＜グループＢ２：フェニレンジアミン、４－アミノ安息香酸４－アミノフェニル、ビス（４－アミノフェニル）テレフタレート、４，４’－ジアミノベンズアニリド、及びＮ，Ｎ’－ビス（４－アミノフェニル）テレフタルアミド＞
前記一般式（１－１）及び（１－２）において、前記グループＡ１からなる群から選択される少なくとも１種のテトラカルボン酸二無水物の残基であるＡ、及び、前記グループＢ１からなる群から選択される少なくとも１種のジアミンの残基であるＢの少なくとも一方を含有し、
前記一般式（１－１）及び（１－２）中に含まれる全てのＲに対する９５．０％以上が炭素数１～１０のアルキル基であり、
更に、下記一般式（２）

<Group A2: pyromellitic acid dianhydride, 3,3', 4,4'-biphenyltetracarboxylic dianhydride, and p-phenylenebis (trimeritate anhydride)>
<Group B1: 2,2'-bis (trifluoromethyl) benzidine, 4,4'-diaminodiphenyl ether, bis (4-aminophenyl) sulfone, and bis [4- (4-aminophenoxy) phenyl] sulfone>
<Group B2: Phenylene diamine, 4-aminophenyl 4-aminobenzoic acid, bis (4-aminophenyl) terephthalate, 4,4'-diaminobenzanilide, and N, N'-bis (4-aminophenyl) terephthalamide. ＞
In the general formulas (1-1) and (1-2), it consists of A which is a residue of at least one tetracarboxylic dianhydride selected from the group consisting of the group A1 and the group B1. Containing at least one of B, which is a residue of at least one diamine selected from the group,
95.0% or more of all R contained in the general formulas (1-1) and (1-2) are alkyl groups having 1 to 10 carbon atoms.
Furthermore, the following general formula (2)

{一般式（２）において、Ｘは下記式（ｘ１）～（ｘ４）

{In the general formula (2), X is the following formulas (x1) to (x4).

（式（ｘ３）において、Ｌは、－Ｏ－、－Ｓ－、－ＣＨ_２－、－ＣＨ（ＣＨ_３）－、－Ｃ（ＣＨ_３）_２－、－Ｃ（ＣＦ_３）_２－、又は－ＣＯ－を表し、＊は結合手を表す。）で表される構造からなる群から選択される少なくとも１つの２価の基を表し、Ｂは前記グループＢ１及び前記グループＢ２からなる群から選択される少なくとも１種のジアミンの残基である２価の基を表す。}で表される構成単位を有していてもよく、
ゲル浸透クロマトグラフィーのポリスチレン換算による重量平均分子量が１０８，０００以上である。

(In equation (x3), L is -O-, -S-, -CH _2- , -CH (CH ₃ )-, -C (CH ₃ ) _2- , -C (CF ₃ ) _2- , or. -CO-, * represents at least one divalent group selected from the group consisting of the structures represented by), and B represents the group consisting of the group B1 and the group B2. Represents a divalent group that is a residue of at least one diamine to be made. } May have a structural unit represented by
The polystyrene-equivalent weight average molecular weight of gel permeation chromatography is 108,000 or more.

Conventionally, as a method for producing a polyimide film, a method for producing a polyimide film by forming a coating film using a polyimide varnish in which soluble polyimide is dissolved in a solvent and drying the solvent, and a method for producing a polyimide film using a polyimide precursor solution are used. There are two methods for producing a polyimide film by forming a body coating film and imidizing the polyimide precursor coating film by heating.
However, the polyimide film produced by the manufacturing method using soluble polyimide has a problem that the optical strain is large and the phase difference in the film thickness direction is particularly large, and this tendency is particularly felt when a polyimide having a rigid skeleton having a high elastic modulus is used. Was strong.
On the other hand, the polyimide film produced by the manufacturing method using the polyimide precursor has a problem that the bending resistance is lowered although the optical strain is improved.

The phase difference is caused by the anisotropy of the refractive index. In the case of polymers, the anisotropy of the refractive index generally occurs when the polymer chains are not randomly present in the solid and are arranged in a directional and regular manner. Compared with other resins, polyimide has few bendable bond points in the chemical structure, so that linear molecular structures tend to increase in the polymer chain. In particular, when a polyimide varnish having a rigid skeleton with a high elastic modulus was used, the linear molecular structure was easily folded regularly in a state of being oriented in the film thickness direction at the time of forming the coating film, and was formed by drying the solvent. It is assumed that the phase difference in the film thickness direction becomes large in the polyimide film.
On the other hand, the polyimide precursor has a higher skeleton flexibility than the polyimide, and tends to be present in an irregular shape in the coating film. By imidizing the polyimide precursor existing in such an irregular state in a substantially solid layer, it is easy to take an irregular structure even after the polyimide is formed. As a result, it is presumed that the phase difference tends to be lower in the manufacturing method of forming the polyimide film by heating after forming the polyimide precursor.

When the decomposition temperature of about 140 ° C. is exceeded, polyamic acid, which is a general polyimide precursor, undergoes a decomposition reaction and an equilibrium reaction that return to the raw material tetracarboxylic acid dianhydride and diamine. When polyamic acid, which is a general polyimide precursor, is heated and imidized, it is heated at a temperature higher than the decomposition temperature of polyamic acid. Therefore, heating for imidization always causes a decomposition reaction and causes a decrease in molecular weight. Therefore, the molecular weight of the polyimide precursor is not maintained after imidization and is lowered. It is presumed that due to this decrease in molecular weight, the polyimide film produced by the production method using the polyimide precursor has a decrease in bending resistance.

On the other hand, the polyimide precursor resin according to one embodiment of the present invention is 95 with respect to R of all −COOR groups (R is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms) contained in the polyimide precursor resin. .0% or more are alkyl groups having 1 to 10 carbon atoms, that is, 95.0% or more of all -COOR groups contained in the polyimide precursor resin are alkyl ester groups, and polystyrene for gel penetration chromatography is used. The converted weight average molecular weight is 108,000 or more. Therefore, the polyimide precursor resin according to one embodiment of the present invention suppresses decomposition even when heated at a high temperature for imidization, is unlikely to cause a decrease in molecular weight, and maintains a weight average molecular weight of 106,000 or more. It can be done.
Further, since the polyimide precursor resin according to one embodiment of the present invention is a polyimide precursor resin having the specific structural unit, it is possible to provide a polyimide film having sufficient transparency and high elasticity. Moreover, since the molecular weight does not decrease even if the heat imidization is performed as described above and the high molecular weight above a specific level can be maintained, the decrease in bending resistance due to the heat imidization is suppressed and the phase difference is further reduced. It is possible to provide a method for producing a polyimide film.

In addition, polyamic acid, which is a conventional polyimide precursor, is easily decomposed in the presence of water and has poor storage stability. On the other hand, the polyimide precursor resin according to one embodiment of the present invention has good storage stability because most of the carboxy groups are esterified and the decomposition reaction due to moisture is suppressed.
Further, the polyamic acid, which is a conventional polyimide precursor, has low solubility in a low-polarity solvent due to hydrogen bonds between the carboxylic acids of the polyamic acid. On the other hand, the polyimide precursor resin according to one embodiment of the present invention has good solubility in a low-polarity solvent because the carboxy group is esterified, and when the dissolution concentration of the resin is the same, It has the advantage of being able to have a lower viscosity than polyamic acid.
Hereinafter, the details of the polyimide precursor resin according to the embodiment of the present invention will be described.

In the general formulas (1-1) and (1-2), A is a tetravalent residue of at least one tetracarboxylic dianhydride selected from the group consisting of the group A1 and the group A2. Represents the basis of.
The group A1 is a 4,4'-(hexafluoroisopropyridene) diphthalic acid dianhydride, a 4,4'-oxydiphthalic acid dianhydride, a cyclobutanetetracarboxylic dianhydride, and the chemical formula (a-1). It is composed of the represented acid dianhydride, and all of them provide a structural unit having improved transparency and good elastic coefficient. Including a structure in which aromatic rings are linked with an alkylene group or an ether group which may be substituted with fluorine can inhibit the transfer of charges in the skeleton by breaking the conjugation of π electrons in the polyimide skeleton. Transparency is improved from the point of view. In addition, when an aliphatic ring is included, transparency is improved in that the transfer of charges in the skeleton can be inhibited by breaking the conjugation of π electrons in the polyimide skeleton. Further, in the acid dianhydride represented by the chemical formula (a-1), since the main chain contains a parabiphenylene group having a twisted dihedral angle via an ester bond, the skeleton is formed by breaking the conjugation of π electrons. Transparency is improved in that it can inhibit the movement of charges within. Further, when an aromatic ring or an aliphatic ring is contained, the elastic modulus becomes good.
In the group A1, 4,4'-(hexafluoroisopropyridene) diphthalic acid dianhydride, 4,4'-oxydiphthalic acid dianhydride and the acid dianhydride represented by the chemical formula (a-1) are used. And, there is a tendency to further improve the solvent solubility of the polyimide from the point that it has a bending site between the aromatic rings, and when cyclobutanetetracarboxylic acid dianhydride is used, the optical strain of the polyimide film is further improved from the point that it is an aliphatic skeleton. Tends to reduce.

Group A2 consists of pyromellitic acid dianhydride, 3,3', 4,4'-bifertetracarboxylic dianhydride, and p-phenylenebis (trimeritate anhydride), all of which increase the elastic modulus. Give a constituent unit. Since all of these contain an aromatic ring and have a rigid structure, the polymers can easily form a stacking structure by π-π interaction and improve the elastic modulus.

In the general formulas (1-1) and (1-2), B represents a divalent group which is a residue of at least one diamine selected from the group consisting of the group B1 and the group B2.
Group B1 consists of 2,2'-bis (trifluoromethyl) benzidine, 4,4'-diaminodiphenyl ether, bis (4-aminophenyl) sulfone, and bis [4- (4-aminophenoxy) phenyl] sulfone. , Both provide a structural unit that improves transparency and has a good elastic modulus. When a fluorine atom is contained, the electronic state in the polyimide skeleton can be made difficult to transfer charge, and the transparency is improved. Including a structure in which aromatic rings are linked to each other with a sulfonyl group or an ether group improves transparency in that the transfer of charges in the skeleton can be inhibited by breaking the conjugation of π electrons in the polyimide skeleton. Further, when an aromatic ring is contained, the elastic modulus becomes good.
In Group B1, 2,2'-bis (trifluoromethyl) benzidine, 4,4'-diaminodiphenyl ether, and bis (4-aminophenyl) sulfone have twisting and bending sites between aromatic rings. Therefore, there is a tendency to further reduce the optical distortion of the polyimide film from the point that the stacking of the polymer can be suppressed. Further, when bis [4- (4-aminophenoxy) phenyl] sulfone is used, the number of bending portions is increased, and the stacking structure can be suppressed, so that the solvent solubility of polyimide tends to be further improved.

Group B2 includes phenylenediamine, 4-aminophenyl 4-aminobenzoic acid, bis (4-aminophenyl) terephthalate, 4,4'-diaminobenzanilide, and N, N'-bis (4-aminophenyl) terephthalamide. In each case, a structural unit that increases the elastic ratio is given. Since all of these contain an aromatic ring and have a rigid structure, the intermolecular force due to π-π interaction or hydrogen bond becomes strong, and the elastic modulus is improved.

The polyimide precursor resin according to one embodiment of the present invention is at least one tetracarboxylic acid dianhydride selected from the group consisting of the group A1 in the general formulas (1-1) and (1-2). Since it contains at least one of A, which is a residue of the above, and B, which is a residue of at least one diamine selected from the group consisting of the group B1, the transparency is improved and the elastic modulus is good. As described above, a polyimide film having a high elastic modulus while having sufficient transparency by a combination of these constituent units, which always contains the constituent units and may further contain a constituent unit for improving the elastic modulus. Can be provided.

The polyimide precursor resin according to one embodiment of the present invention is 50% or more, more 60% or more, more than 70% with respect to all A contained in the general formulas (1-1) and (1-2). % Or more is preferably a residue of at least one tetracarboxylic dianhydride selected from the group consisting of the group A1.
On the other hand, the polyimide precursor resin according to one embodiment of the present invention is 50% or less, more 40% or less, based on all A contained in the general formulas (1-1) and (1-2). Further, 30% or less may be residues of at least one tetracarboxylic dianhydride selected from the group consisting of the group A2.

The polyimide precursor resin according to one embodiment of the present invention is 50% or more, more 60% or more, more than 70% with respect to all B contained in the general formulas (1-1) and (1-2). % Or more is preferably a residue of at least one tetracarboxylic dianhydride selected from the group consisting of the group B1.
On the other hand, the polyimide precursor resin according to one embodiment of the present invention is 50% or less, more 40% or less, with respect to all B contained in the general formulas (1-1) and (1-2). Further, 30% or less may be residues of at least one tetracarboxylic dianhydride selected from the group consisting of the group B2.

In the polyimide precursor resin according to one embodiment of the present invention, A is used in the general formulas (1-1) and (1-2) from the viewpoint of the characteristic balance of transparency and elasticity and the solubility in a solvent. At least one selected from the group consisting of 4,4'-(hexafluoroisopropylidene) diphthalic acid anhydride, cyclobutanetetracarboxylic acid dianhydride, and acid dianhydride represented by the above chemical formula (a-1). It is preferable to represent a tetravalent group which is a residue of the tetracarboxylic acid dianhydride, and further comprises a cyclobutane tetracarboxylic acid dianhydride and an acid dianhydride represented by the chemical formula (a-1). More preferably, it is a tetravalent group that is a residue of at least one tetracarboxylic acid dianhydride selected from the group.

Further, in the polyimide precursor resin according to one embodiment of the present invention, B is 2,2'-bis in the general formulas (1-1) and (1-2) from the viewpoint of transparency and solvent solubility. It preferably represents a divalent group that is a residue of (trifluoromethyl) benzidine.

The polyimide precursor resin according to one embodiment of the present invention has an alkyl group having 1 to 10 carbon atoms in an amount of 95.0% or more with respect to all R contained in the general formulas (1-1) and (1-2). Is.
The alkyl group having 1 to 10 carbon atoms may be linear, branched or cyclic, and may be, for example, a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group or a t-butyl group. Examples thereof include an n-pentyl group, a cyclopentyl group, an n-hexyl group, a cyclohexyl group, and an n-octyl group.
The alkyl group having 1 to 10 carbon atoms in R is preferably an alkyl group having 1 to 6 carbon atoms and having 1 to 4 carbon atoms from the viewpoint of enhancing the desorption performance of alcohol during thermal imidization. It is more preferably a methyl group, an ethyl group, an n-propyl group, or an i-propyl group, and even more preferably a methyl group or an ethyl group.

The polyimide precursor resin according to one embodiment of the present invention has an alkyl group having 1 to 10 carbon atoms having 95.0% or more of all R contained in the general formulas (1-1) and (1-2). However, from the viewpoint of the stability of the polyimide precursor in the atmosphere, the ratio of the alkyl group having 1 to 10 carbon atoms to all R is preferably 98.0% or more, more preferably 99.0% or more. , 100%.

The structural units represented by the general formulas (1-1) and (1-2) in the polyimide precursor resin according to one embodiment of the present invention may contain one kind or two or more kinds, respectively.
The total content of the structural units represented by the general formulas (1-1) and (1-2) is 100 mol% with respect to the total of the structural units in the polyimide precursor resin according to the embodiment of the present invention. However, the polyimide resin according to the embodiment of the present invention contains the configurations represented by the general formulas (1-1) and (1-2) as long as the effects of the present invention are not impaired. It may contain a constituent unit different from the unit.
Even when different structural units are contained, they are represented by the general formulas (1-1) and (1-2) with respect to all the structural units of the polyimide precursor resin according to one embodiment of the present invention. The total content ratio of the constituent units is preferably 80 mol% or more, more preferably 90 mol% or more.

The polyimide precursor resin according to one embodiment of the present invention is further represented by the following general formula (2) from the viewpoint that a polyamide-imide film having a high elastic modulus while having sufficient transparency can be provided. It may have a structural unit.

{一般式（２）において、Ｘは下記式（ｘ１）～（ｘ４）で表される構造からなる群から選択される少なくとも１つの２価の基を表し、Ｂは前記グループＢ１及び前記グループＢ２からなる群から選択される少なくとも１種のジアミンの残基である２価の基を表す。

{In the general formula (2), X represents at least one divalent group selected from the group consisting of the structures represented by the following formulas (x1) to (x4), and B represents the group B1 and the group B2. Represents a divalent group that is a residue of at least one diamine selected from the group consisting of.

（式（ｘ３）において、Ｌは、－Ｏ－、－Ｓ－、－ＣＨ_２－、－ＣＨ（ＣＨ_３）－、－Ｃ（ＣＨ_３）_２－、－Ｃ（ＣＦ_３）_２－、又は－ＣＯ－を表し、＊は結合手を表す。）}

(In equation (x3), L is -O-, -S-, -CH _2- , -CH (CH ₃ )-, -C (CH ₃ ) _2- , -C (CF ₃ ) _2- , or. -CO-, * represents a bond.)}

Among the structures represented by the formulas (x1) to (x4), select from the group consisting of the structures represented by the formulas (x1) to (x3) from the viewpoint of improving high elasticity and bending resistance. One or more of the above formulas are preferable, the structure represented by the formula (x1) or the formula (x2) is more preferable, and the structure represented by the formula (x2) is even more preferable.

B may be similar to the residue of at least one diamine selected from the group consisting of the group B1 and the group B2, and from the viewpoint of transparency, at least one selected from the group consisting of the group B1. It is preferably a residue of the seed diamine, and B may represent a divalent group which is a residue of 2,2'-bis (trifluoromethyl) benzidine in terms of transparency and high modulus. preferable.

In the structural unit represented by the general formula (2), X and B may be independently contained in one type or two or more types.

The total content ratio of the structural units represented by the general formula (2) is preferably 60 mol% or less, further 40, with respect to all the structural units of the polyimide precursor resin according to one embodiment of the present invention. It is more preferably mol% or less.
That is, in the polyimide precursor resin according to one embodiment of the present invention, the total content ratio of the dicarboxylic acid residues may be 0 mol%, but the total tetracarboxylic acid residues and the total dicarboxylic acid residues. It is preferably 60 mol% or less, more preferably 40 mol% or less, based on the total.
Since the dicarboxylic acid residue does not affect the decomposition of the polyimide precursor resin, it can be contained even if it exceeds 50 mol% with respect to all the constituent units of the polyimide precursor resin according to one embodiment of the present invention. be.

Further, the polyimide precursor resin according to one embodiment of the present invention does not have to upset the balance of transparency, double modulus and elastic modulus, and further, in the above general formulas (1-1) and (1-2). , A represents a tetravalent group which is a residue of another tetracarboxylic acid dianhydride different from the group A1 and the group A2, or B is different from the group B1 and the group B2. It may contain a structural unit different from the general formulas (1-1) and (1-2), such as representing a divalent group which is a residue of the diamine of.
Other tetracarboxylic acid dianhydrides different from the group A1 and the group A2, and other diamines different from the group B1 and the group B2 are appropriately selected from the tetracarboxylic acid dianhydrides and diamines used for the polyimide. Examples thereof include tetracarboxylic acid dianhydrides and diamines described in International Publication No. 2018/030410, International Publication No. 2019/078051, International Publication No. 2019/013169 and the like.
Even when the polyimide precursor structural unit different from the general formulas (1-1) and (1-2) is contained, 95.0% of all the −COOR groups contained in the polyimide precursor resin. The above is preferably an alkyl ester group having 1 to 10 carbon atoms.

Remaining of other tetracarboxylic acid dianhydrides different from the group A1 and the group A2 even when the polyimide precursor constituent units different from the general formulas (1-1) and (1-2) are contained. The total content of the groups is preferably 20 mol% or less, more preferably 10 mol% or less, and 5 mol% with respect to the total of all tetracarboxylic acid residues and all dicarboxylic acid residues. It is more preferably less than or equal to, and even more preferably 2 mol% or less.
Further, the total content ratio of the residues of other diamines different from the group B1 and the group B2 is preferably 20 mol% or less, more preferably 10 mol% or less, based on the total of all diamine residues. It is more preferably 5 mol% or less, and even more preferably 2 mol% or less.

The polyimide precursor resin according to one embodiment of the present invention has a structural unit represented by the general formula (1-1), a structural unit represented by the general formula (1-2), and the general formula (2). ), The total of the structural units represented by) is preferably 95% or more, more preferably 98% or more, and even more preferably 100% of all the structural units of the polyimide precursor resin.

The polystyrene-equivalent weight average molecular weight of the polyimide precursor resin according to one embodiment of the present invention is 108,000 or more, preferably 120,000 or more, and more preferably 150,000 or more. It is preferably 1,000,000 or less, more preferably 500,000 or less, and even more preferably 300,000 or less.
When the weight average molecular weight of the polyimide precursor resin is at least the lower limit, bending resistance is good, appearance defects such as cracks and whitening are unlikely to occur after firing, and a film with good transparency can be easily obtained. Is preferable. On the other hand, when it is at least the above upper limit value, it is preferable from the viewpoint that high viscosity is suppressed during synthesis, varnish preparation, and film formation, and it becomes easy to form a film.

The weight average molecular weight of the polyimide precursor resin is such that the polyimide precursor resin is prepared as an N-methylpyrrolidone (NMP) solution having a concentration of 0.5% by weight, and the solution is passed through a syringe filter (pore size: 0.45 μm). After filtering, a 10 mmol% LiBr-NMP solution having a water content of 500 ppm or less was used as a developing solvent, and a GPC device (HLC-8120 manufactured by Toso Co., Ltd., column used: GPC LF-804 manufactured by SHODEX) was used. The measurement is performed under the conditions of a flow rate of 0.5 mL / min and 40 ° C. The weight average molecular weight of the polyimide precursor resin is a polystyrene standard sample having 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) as a reference value for standard polystyrene. Compare the elution time with the calibration curve to determine the weight average molecular weight.

(Manufacturing method of polyimide precursor resin)
The method for producing the polyimide precursor resin according to the embodiment of the present invention is not particularly limited, and for example, one or more kinds of tetracarboxylic acid dianhydrides containing the specific tetracarboxylic acid dianhydride and two or more kinds of tetracarboxylic acid dianhydrides. A step of obtaining a polyamic acid by reacting with one or more kinds of diamines containing the specific diamine, and if necessary, the obtained polyamic acid and a dicarboxylic acid component having an aromatic ring. It has a step of obtaining a polyamide-polyamic acid copolymer by reacting, and can be produced through a step of alkyl esterifying the carboxy group of the obtained polyamic acid or the polyamide-polyamic acid copolymer. can.

The polyamic acid is obtained by reacting the above-mentioned tetracarboxylic dianhydride with the above-mentioned diamine in a solvent. The solvent used for synthesizing the polyamic acid is not particularly limited as long as the above-mentioned tetracarboxylic acid dianhydride and diamine can be dissolved, and for example, an aprotic polar solvent or a water-soluble alcohol-based solvent can be used. In the present invention, among others, N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide, hexamethylphosphoramide, 1,3-dimethyl-2-imidazolidinone, etc. It is preferable to use an organic solvent containing a nitrogen atom; γ-butyrolactone or the like. The organic solvent is a solvent containing a carbon atom.

When the polyamic acid is prepared by combining at least two types of tetracarboxylic dianhydride, at least two types of tetracarboxylic dianhydride are added at once to the polymerization solvent in which the diamine is dissolved to obtain the polyamic acid. At least two tetracarboxylic dianhydrides 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. May be good.
For example, by adding the acid dianhydride represented by the chemical formula (a-1) to the reaction solution in which the diamine is dissolved and reacting the reaction solution, the acid dianhydride represented by the chemical formula (a-1) can be obtained. An amic acid reacted with a diamine is synthesized, a tetracarboxylic acid dianhydride different from the acid dianhydride represented by the chemical formula (a-1) is added thereto, and if necessary, further diamine is added. Polyamic acid may be polymerized. When polymerized by this method, the acid dianhydride represented by the chemical formula (a-1) is introduced into the polyamic acid in a linked form via one diamine.
Polymerizing polyamic acid by such a method is preferable because the positional relationship of tetracarboxylic acid residues having a specific structure can be specified to some extent, and a polyimide film having good surface hardness and excellent bending resistance can be easily obtained.

When a polyamide-polyamic acid copolymer is obtained as required, in the step of obtaining the polyamic acid, for example, 100 mol% of the diamine component is reacted with a mol% of the tetracarboxylic acid dianhydride component in the solvent. Thereby, a polyamic acid can be obtained, and then the polyamic acid is reacted with a (100-a) mol% dicarboxylic acid component in the reaction solution to obtain a polyamide-polyamic acid copolymer. , It is preferable from the viewpoint that a higher molecular weight substance can be obtained.

When the number of moles of diamine in the polyamic acid solution is X and the number of moles of tetracarboxylic acid dianhydride is Y, Y / X is preferably 0.9 or more and 1.1 or less, preferably 0.95 or more. It is more preferably 1.05 or less, further preferably 0.97 or more and 1.03 or less, and particularly preferably 0.99 or more and 1.01 or less. Within such a range, the molecular weight (degree of polymerization) of the polyamic acid obtained can be appropriately adjusted.

In the step of alkyl esterifying the carboxy group of the obtained polyamic acid or the polyamide-polyamic acid copolymer, the alkyl esterification having 1 to 10 carbon atoms is, for example, N, N-dimethylformamide dimethylacetal, N, This can be carried out using N, N-dimethylformamide dialkyl acetals such as N-dimethylformamide diethyl acetal, N, N-dimethylformamide dipropyl acetal. Above all, it is preferable to use N, N-dimethylformamide dimethylacetal from the viewpoint of the reactivity of the esterifying agent and the ease of ring closure during thermal imidization.
For esterification, N, N-dimethylformamide dialkylacetal was added to the polyamic acid solution at 25 ° C. so that the number of moles of the tetracarboxylic acid dianhydride constituting the polyamic acid was doubled. It is preferable to stir for about an hour. It is more preferable to use N, N-dimethylacetamide as the solvent of the polyamic acid solution from the viewpoint of improving transparency.

The structure of the polyimide precursor resin according to one embodiment of the present invention can be obtained by using NMR analysis, various mass spectrometry, elemental analysis, IR analysis and the like.

II. Method for Producing Polyimide Film In the method for producing a polyimide film according to the first embodiment of the present invention, a polyimide precursor resin composition containing the polyimide precursor resin according to the first embodiment of the present invention and an organic solvent is used. The process of preparation and
A step of applying the polyimide precursor resin composition to a support to form a polyimide precursor resin coating film, and a step of forming the polyimide precursor resin coating film.
The step of imidizing the polyimide precursor resin by heating the polyimide precursor resin coating film is included.

In the method for producing a polyimide film according to an embodiment of the present invention, the polyimide film is produced by thermal imidization using a polyimide precursor resin having a specific structure and molecular weight according to the embodiment of the present invention. Therefore, as described above, the polyimide tends to have an irregular structure in the film, and the polyimide maintains a specific high molecular weight without being decomposed in the process of thermal imidization, so that it is sufficiently transparent. It is possible to produce a polyimide film having properties, suppressing a decrease in bending resistance, and further reducing a phase difference.

In the method for producing a polyimide film according to one embodiment of the present invention, at least one of the polyimide precursor resin coating film and the imidized coating film obtained by imidizing the polyimide precursor resin coating film is further stretched. It may have a step (hereinafter referred to as a stretching step).
Hereinafter, an example of a method for manufacturing a polyimide film will be described in detail for each process.

1. 1. Polyimide precursor resin composition preparation step The polyimide precursor resin composition may contain the polyimide precursor resin according to one embodiment of the present invention and an organic solvent, and may contain additives and the like as necessary. good.
The polyimide precursor resin according to the embodiment of the present invention may be the same as described above, and thus the description thereof is omitted here.
The polyimide precursor resin solution obtained by the synthesis reaction may be used as it is, and other components may be mixed therewith, if necessary, or the solvent of the polyimide precursor resin solution obtained by the synthesis reaction is dried and separated. It may be used by dissolving it in the solvent of.

The organic solvent used in the polyimide precursor resin composition is not particularly limited as long as the polyimide precursor resin can be dissolved. For example, it contains nitrogen atoms such as N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide, hexamethylphosphoramide, and 1,3-dimethyl-2-imidazolidinone. Organic solvent; γ-butyrolactone and the like can be used.

Examples of the additive that may be contained if necessary include a silica filler for facilitating winding, a surfactant for improving film forming property and defoaming property, and the like.

The content of the polyimide precursor resin in the polyimide precursor resin composition is 50% by mass or more in the solid content of the resin composition from the viewpoint of forming a polyimide film having a uniform coating film and handleable strength. It is preferably 60% by mass or more, and the upper limit may be appropriately adjusted depending on the contained components.
The organic solvent in the polyimide precursor resin composition is preferably 40% by mass or more, and more preferably 50% by mass or more in the resin composition from the viewpoint of forming a uniform coating film and a polyimide film. It is preferable, and it is preferably 99% by mass or less.

Further, it is preferable that the water content of the polyimide precursor resin composition is 1000 ppm or less because 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 be easily decomposed.
The water content of the polyimide precursor resin composition can be determined using a Karl Fisher Moisture Meter (for example, Mitsubishi Chemical Corporation, trace moisture measuring device CA-200 type).

The polyimide precursor resin composition has a viscosity at 25 ° C. measured by a rotational viscometer of preferably 1000 mPa · s or more, more preferably 3000 mPa · s or more, preferably 15,000 mPa · s or less, and more preferably 10,000 mPa · s. Below, it is more preferably 6000 Pa · s or less.
When the viscosity of the polyimide precursor resin composition is at least the above lower limit value at the time of producing the polyimide film, it is preferable from the viewpoint that uneven film thickness and uneven drying at the time of film formation are less likely to occur, and when it is at least the above upper limit value, it is preferable. Filtration is performed to remove foreign substances as a preparation before coating, which is preferable because the resin composition has good permeability.
Here, the viscosity of the polyimide precursor resin composition is determined by the method described in JIS K7117-1 using a single cylindrical rotary viscometer (for example, TVB-10 type viscometer manufactured by Toki Sangyo Co., Ltd.). It can be measured at 25 ° C.

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

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

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

The drying time may be appropriately adjusted according to the film thickness of the polyimide precursor resin coating film, the type of solvent, the drying temperature, etc., but is usually 1 minute to 60 minutes, preferably 2 minutes to 30 minutes. If it exceeds the upper limit, it is not preferable from the viewpoint of the production efficiency of the polyimide film. On the other hand, if it is below the lower limit, the appearance of the obtained polyimide film may be affected by the rapid drying of the solvent.

The method for drying the solvent is not particularly limited as long as the solvent can be dried at the above temperature, and for example, an oven, a drying oven, a hot plate, infrared heating, or the like can be used.
When a high degree of control of optical properties is required, the atmosphere of the solvent when it is dried is preferably an inert gas atmosphere. The inert gas atmosphere is preferably a nitrogen atmosphere, preferably an oxygen concentration of 100 ppm or less, and more preferably 50 ppm or less. Heat treatment in the atmosphere can oxidize the film, causing it to color or reduce its performance.

3. 3. Thermal imidization step In the method for producing a polyimide film according to the embodiment of the present invention, imidization is performed by heating.
As described above, in thermal imidization, the coating film is formed and then imidized in the state of the polyimide precursor, but in the film-formed state, the amide bond of the polyimide precursor is bent due to the influence of the movement of the molecular chain due to heat. This is because the polymer chains in the obtained polyimide are likely to have a bent molecular structure, and a polyimide film having a low phase difference can be obtained.

In order to reduce the amount of residual solvent in the polyimide film and improve bending resistance, the polyimide precursor resin coating film is peeled off from the support used for coating and then heated to imide the polyimide precursor. It is preferable to carry out the step of converting. By peeling from the support used for coating and heating in a state where both surfaces of the film are not in contact with the support or the like, the solvent can be volatilized from both surfaces of the film, and the residual solvent can be sufficiently removed. Can be reduced.
Further, it is preferable to heat the polyimide precursor resin coating film after peeling from the support after fixing the end portion from the viewpoint of preventing shrinkage during heating.
As a method of fixing the end portion of the polyimide precursor resin coating, for example, when the polyimide precursor resin coating is sheet-like, a metal having substantially the same outer dimensions and appropriate inner dimensions as the polyimide precursor resin coating. A method of sandwiching the polyimide precursor resin coating film by using two frames and fixing the two metal frames and the polyimide precursor resin coating film with a fixing jig can be mentioned.
Further, for example, when the polyimide precursor resin coating film is in the form of a roll, for example, a polyimide precursor is used by using a device capable of transporting the resin film by grasping the left and right ends of the continuous resin film with a fixing jig such as a clip. A method of fixing the end portion of the resin coating film can be mentioned.

When the manufacturing method has a stretching step, the thermal imidization step may be performed on the polyimide precursor in the polyimide precursor resin coating film before the stretching step, or the polyimide precursor after the stretching step. This may be performed on the polyimide precursor in the resin coating film, or on both the polyimide precursor in the polyimide precursor resin coating film before the stretching step and the polyimide precursor existing in the film after the stretching step. You may go there.

The imidization temperature may be appropriately selected according to the structure of the polyimide precursor so that the polymer chain in the polyimide precursor can easily take a bent molecular structure.
Usually, the temperature rise start temperature is preferably 30 ° C. or higher, and more preferably 100 ° C. or higher. On the other hand, the temperature rise end temperature is preferably 250 ° C. or higher.

The temperature rising rate is preferably appropriately selected depending on the film thickness of the obtained polyimide film, and when the film thickness of the polyimide film is thick, it is preferable to slow down the temperature rising rate.
From the viewpoint of the production efficiency of the polyimide film, it is preferably 5 ° C./min or more. On the other hand, the upper limit of the temperature rising rate is usually 50 ° C./min or less, preferably 40 ° C./min or less, and more preferably 30 ° C./min or less. It is preferable to set the temperature rise rate from the viewpoints of suppressing poor appearance and decrease in strength of the film, controlling whitening due to the imidization reaction, and improving light transmission.

The temperature rise may be continuous or stepwise, but it is preferable to raise the temperature continuously because the polymer chain in the obtained polyimide tends to have a bent molecular structure. Further, the temperature rising rate may be constant or may be changed in the middle of the above-mentioned entire temperature range.

The atmosphere at the time of temperature rise of imidization is preferably an inert gas atmosphere. The inert gas atmosphere is preferably a nitrogen atmosphere, preferably an oxygen concentration of 500 ppm or less, more preferably 200 ppm or less, and even more preferably 100 ppm or less. Heat treatment in the atmosphere can oxidize the film, causing it to color or reduce its performance.

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

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

In order to obtain the final polyimide film, it is preferable to proceed the reaction to 90% or more, further 95% or more, and further 100% of imidization.
In order to allow the reaction to proceed to 90% or more and even 100% of imidization, it is preferable to keep the temperature at the end temperature for a certain period of time, and the holding time is usually 1 minute to 180 minutes, further 5 minutes to 150 minutes. It is preferably a minute.

4. Stretching Step It may have 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. When the stretching step is provided, it is particularly preferable to include a step of stretching the coating film after imidization from the viewpoint of improving the surface hardness of the polyimide film.

It is preferable to carry out the step of stretching 101% or more and 10000% or less while heating at 80 ° C. or higher when the initial dimension before carrying out the stretching is 100%.
The heating temperature during stretching is preferably in the range of the glass transition temperature of the polyimide or the polyimide precursor ± 50 ° C., and preferably in 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 stretching step may be performed at the same time as the imidization step. Stretching the imidized coating film after imidization of 80% or more, further 90% or more, further 95% or more, particularly substantially 100% imidization improves the surface hardness of the polyimide film. It is preferable from the point of view.

The draw ratio of the polyimide film is preferably 101% or more and 10000% or less, and 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 at the time of stretching is not particularly limited, and is selected according to the type of stretching device and the like. Further, the stretching method is not particularly limited, and it is possible to stretch while passing through a heating furnace by using a stretching device having a transporting device such as a tenter. The polyimide film may be stretched in only one direction (longitudinal stretching or transverse stretching), or may be stretched in two directions by simultaneous biaxial stretching, sequential biaxial stretching, diagonal stretching, or the like.

5. Manufactured Polyimide Film The polyimide film produced by the method for producing the polyimide film according to the first embodiment of the present invention is described in the following general formula (1).

（一般式（１）において、Ａは、下記グループＡ１及び下記グループＡ２からなる群から選択される少なくとも１種のテトラカルボン酸二無水物の残基である４価の基を表し、Ｂは下記グループＢ１及び下記グループＢ２からなる群から選択される少なくとも１種のジアミンの残基である２価の基を表す。）で表される構成単位を有し、
＜グループＡ１：４，４’－（ヘキサフルオロイソプロピリデン）ジフタル酸二無水物、４，４’－オキシジフタル酸二無水物、シクロブタンテトラカルボン酸二無水物、及び下記化学式（ａ－１）で表される酸二無水物＞

(In the general formula (1), A represents a tetravalent group which is a residue of at least one tetracarboxylic acid dianhydride selected from the group consisting of the following groups A1 and the following groups A2, and B is the following. It has a structural unit represented by a divalent group which is a residue of at least one diamine selected from the group consisting of group B1 and the following group B2).
<Group A1: 4,4'-(hexafluoroisopropyridene) diphthalic acid dianhydride, 4,4'-oxydiphthalic acid dianhydride, cyclobutanetetracarboxylic acid dianhydride, and the following chemical formula (a-1). Acid dianhydride>

＜グループＡ２：ピロメリット酸二無水物、３，３’，４，４’－ビフェニルテトラカルボン酸ニ無水物、及びｐ－フェニレンビス（トリメリテート無水物）＞
＜グループＢ１：２，２’－ビス（トリフルオロメチル）ベンジジン、４，４’－ジアミノジフェニルエーテル、ビス（４－アミノフェニル）スルホン、及びビス［４－（４－アニノフェノキシ）フェニル］スルホン＞
＜グループＢ２：フェニレンジアミン、４－アミノ安息香酸４－アミノフェニル、ビス（４－アミノフェニル）テレフタレート、４，４’－ジアミノベンズアニリド、及びＮ，Ｎ’－ビス（４－アミノフェニル）テレフタルアミド＞
前記一般式（１）において、前記グループＡ１からなる群から選択される少なくとも１種のテトラカルボン酸二無水物の残基であるＡ、及び、前記グループＢ１からなる群から選択される少なくとも１種のジアミンの残基であるＢの少なくとも一方を含有し、
更に、下記一般式（２）

<Group A2: pyromellitic dianhydride, 3,3', 4,4'-biphenyltetracarboxylic dianhydride, and p-phenylenebis (trimeritate anhydride)>
<Group B1: 2,2'-bis (trifluoromethyl) benzidine, 4,4'-diaminodiphenyl ether, bis (4-aminophenyl) sulfone, and bis [4- (4-aninophenoxy) phenyl] sulfone>
<Group B2: Phenylene diamine, 4-aminophenyl 4-aminobenzoic acid, bis (4-aminophenyl) terephthalate, 4,4'-diaminobenzanilide, and N, N'-bis (4-aminophenyl) terephthalamide. ＞
In the general formula (1), A which is a residue of at least one tetracarboxylic dianhydride selected from the group consisting of the group A1 and at least one selected from the group consisting of the group B1. Containing at least one of B, which is a residue of the diamine of
Furthermore, the following general formula (2)

{一般式（２）において、Ｘは下記式（ｘ１）～（ｘ４）

{In the general formula (2), X is the following formulas (x1) to (x4).

（式（ｘ３）において、Ｌは、－Ｏ－、－Ｓ－、－ＣＨ_２－、－ＣＨ（ＣＨ_３）－、－Ｃ（ＣＨ_３）_２－、－Ｃ（ＣＦ_３）_２－、又は－ＣＯ－を表し、＊は結合手を表す。）で表される構造からなる群から選択される少なくとも１つの２価の基を表し、Ｂは前記グループＢ１及び前記グループＢ２からなる群から選択される少なくとも１種のジアミンの残基である２価の基を表す。}で表される構成単位を有していてもよいポリイミド樹脂を含有する。

(In equation (x3), L is -O-, -S-, -CH _2- , -CH (CH ₃ )-, -C (CH ₃ ) _2- , -C (CF ₃ ) _2- , or. -CO-, * represents at least one divalent group selected from the group consisting of the structures represented by), and B represents the group consisting of the group B1 and the group B2. Represents a divalent group that is a residue of at least one diamine to be made. } Contains a polyimide resin which may have a structural unit represented by.

A, which is a residue of tetracarboxylic acid dianhydride in the structural unit represented by the general formula (1), and B, which is a residue of diamine, are in the polyimide precursor resin of one embodiment of the present invention. It is the same as A which is a residue of tetracarboxylic acid dianhydride and B which is a residue of diamine in the structural unit represented by the general formula (1-1) or the general formula (1-2). Good.
Further, the structural unit represented by the general formula (2) may be the same as the structural unit represented by the general formula (2) in the polyimide precursor resin of one embodiment of the present invention.
It is preferable that the polyimide film of the first embodiment of the present invention has the same characteristics as the polyimide film of the second embodiment of the present invention described later.

III. Method of manufacturing a laminate
The first method for producing a laminate of the present invention is
A step of manufacturing a polyimide film by the method of manufacturing a polyimide film according to the first embodiment of the present invention.
A step of applying a composition for a hard coat layer containing at least one of a radically polymerizable compound and a cationically polymerizable compound to at least one surface of the polyimide film to form a coating film for forming a hard coat layer.
The present invention comprises a step of forming a hard coat layer containing at least one polymer of a radically polymerizable compound and a cationically polymerizable compound by curing the coating film for forming the hard coat layer.

Regarding the step of manufacturing the polyimide film by the method of manufacturing the polyimide film of the first embodiment of the present invention, the above II. Since the method may be the same as that described in the method for manufacturing a polyimide film, the description thereof is omitted here.

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, regarding the radically polymerizable compound, the cationically polymerizable compound, the polymerization initiator and the additive contained in the composition for forming the hard coat layer, the hard coat of the laminate of the second embodiment of the present invention described later will be described. The same ones described in the layer can be used, and 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 the polyimide film produced by the method for producing a polyimide film according to the first embodiment of the present invention, for example, polyimide is used. A method of applying the composition for forming a hard coat layer to at least one surface of a film by a known coating means can be mentioned.
The coating means is not particularly limited as long as it can be applied with a desired film thickness, and examples thereof include the same means as those for applying the polyimide precursor resin composition to 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 vacuum drying, heat drying, and a method of combining these drying methods. When drying at normal pressure, it is preferable to dry at 30 ° C. or higher and 110 ° C. or lower.

Depending on the polymerizable group 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 to the coating film and dried as necessary. 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 cationically polymerizable compound is formed on at least one surface of the polyimide film. Can be formed.

Ultraviolet rays, visible light, electron beams, ionizing radiation and the like are mainly used for light irradiation. In the case of ultraviolet curing, ultraviolet rays emitted from light rays such as 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 radiation source is about 50 to 5000 mJ / cm ² as the integrated exposure amount at the ultraviolet wavelength of 365 nm.
When heating, it is usually treated at a temperature of 40 ° C. or higher and 120 ° C. or lower. Further, the reaction may be carried out by leaving it at room temperature (25 ° C.) for 24 hours or more.

IV. Polyimide film The polyimide film of the second embodiment of the present invention has the following general formula (1').

（一般式（１’）において、Ａは、下記グループＡ１及び下記グループＡ２からなる群から選択される少なくとも１種のテトラカルボン酸二無水物の残基である４価の基を表し、Ｂは下記グループＢ１及び下記グループＢ２からなる群から選択される少なくとも１種のジアミンの残基である２価の基を表す。）で表される構成単位を有し、
＜グループＡ１：４，４’－（ヘキサフルオロイソプロピリデン）ジフタル酸二無水物、４，４’－オキシジフタル酸二無水物、シクロブタンテトラカルボン酸二無水物、及び下記化学式（ａ－１）で表される酸二無水物＞

(In the general formula (1'), A represents a tetravalent group which is a residue of at least one tetracarboxylic acid dianhydride selected from the group consisting of the following groups A1 and the following groups A2, and B is. It has a structural unit represented by (representing a divalent group which is a residue of at least one diamine selected from the group consisting of the following group B1 and the following group B2).
<Group A1: 4,4'-(hexafluoroisopropyridene) diphthalic acid dianhydride, 4,4'-oxydiphthalic acid dianhydride, cyclobutanetetracarboxylic acid dianhydride, and the following chemical formula (a-1). Acid dianhydride>

＜グループＡ２：ピロメリット酸二無水物、３，３’，４，４’－ビフェニルテトラカルボン酸ニ無水物、及びｐ－フェニレンビス（トリメリテート無水物）＞
＜グループＢ１：２，２’－ビス（トリフルオロメチル）ベンジジン、４，４’－ジアミノジフェニルエーテル、ビス（４－アミノフェニル）スルホン、及びビス［４－（４－アニノフェノキシ）フェニル］スルホン＞
＜グループＢ２：フェニレンジアミン、４－アミノ安息香酸４－アミノフェニル、ビス（４－アミノフェニル）テレフタレート、４，４’－ジアミノベンズアニリド、及びＮ，Ｎ’－ビス（４－アミノフェニル）テレフタルアミド＞
前記一般式（１’）において、Ａは、少なくとも前記化学式（ａ－１）で表される酸二無水物の残基である４価の基を含有し、
更に、下記一般式（２）

<Group A2: pyromellitic dianhydride, 3,3', 4,4'-biphenyltetracarboxylic dianhydride, and p-phenylenebis (trimeritate anhydride)>
<Group B1: 2,2'-bis (trifluoromethyl) benzidine, 4,4'-diaminodiphenyl ether, bis (4-aminophenyl) sulfone, and bis [4- (4-aninophenoxy) phenyl] sulfone>
<Group B2: Phenylene diamine, 4-aminophenyl 4-aminobenzoic acid, bis (4-aminophenyl) terephthalate, 4,4'-diaminobenzanilide, and N, N'-bis (4-aminophenyl) terephthalamide. ＞
In the general formula (1'), A contains at least a tetravalent group which is a residue of the acid dianhydride represented by the chemical formula (a-1).
Furthermore, the following general formula (2)

{一般式（２）において、Ｘは下記式（ｘ１）～（ｘ４）

{In the general formula (2), X is the following formulas (x1) to (x4).

（式（ｘ３）において、Ｌは、－Ｏ－、－Ｓ－、－ＣＨ_２－、－ＣＨ（ＣＨ_３）－、－Ｃ（ＣＨ_３）_２－、－Ｃ（ＣＦ_３）_２－、又は－ＣＯ－を表し、＊は結合手を表す。）で表される構造からなる群から選択される少なくとも１つの２価の基を表し、Ｂは前記グループＢ１及び前記グループＢ２からなる群から選択される少なくとも１種のジアミンの残基である２価の基を表す。}で表される構成単位を有していてもよいポリイミド樹脂を含有し、
ＪＩＳ Ｋ７３６１－１に準拠して測定する全光線透過率が、膜厚４０μｍの換算値で８５．０％以上であり、ＪＩＳ Ｋ７３７３－２００６に準拠して算出される黄色度を膜厚（μｍ）で除した値が、０．１５未満であり、
波長５９０ｎｍにおける厚み方向の複屈折率が、０．０２５未満であり、
１０ｍｍ×１５０ｍｍの試験片を、ＪＩＳ Ｋ７１２７に準拠し、引張り速度を５０ｍｍ／分、チャック間距離を１００ｍｍとして、２５℃で測定する引張試験における引張弾性率が４．０ＧＰａ以上であり、且つ、下記動的屈曲試験において、屈曲回数が、１０万回以上である、ポリイミドフィルムである。
（動的屈曲試験）
２０ｍｍ×１００ｍｍの試験片を、長辺の半分の位置で湾曲させて、平行に配置した金属板で挟み、両側の金属板間の距離が６０ｍｍから２．５ｍｍとなるように２５℃、６０％相対湿度（ＲＨ）の環境下で、１分間に９０回の屈曲回数で繰り返し変化させ、試験片の屈曲を繰り返す。

(In equation (x3), L is -O-, -S-, -CH _2- , -CH (CH ₃ )-, -C (CH ₃ ) _2- , -C (CF ₃ ) _2- , or. -CO-, * represents at least one divalent group selected from the group consisting of the structures represented by), and B represents the group consisting of the group B1 and the group B2. Represents a divalent group that is a residue of at least one diamine to be made. Contains a polyimide resin that may have a structural unit represented by }.
The total light transmittance measured according to JIS K7361-1 is 85.0% or more in terms of the film thickness of 40 μm, and the yellowness calculated according to JIS K7373-2006 is the film thickness (μm). The value divided by is less than 0.15,
The birefringence in the thickness direction at a wavelength of 590 nm is less than 0.025.
A test piece of 10 mm × 150 mm has a tensile elastic modulus of 4.0 GPa or more in a tensile test measured at 25 ° C., with a tensile speed of 50 mm / min and a distance between chucks of 100 mm, in accordance with JIS K7127, and is as follows. A polyimide film having a bending count of 100,000 or more in a dynamic bending test.
(Dynamic bending test)
A 20 mm × 100 mm test piece is curved at the half position of the long side, sandwiched between metal plates arranged in parallel, and 25 ° C., 60% so that the distance between the metal plates on both sides is 60 mm to 2.5 mm. In a relative humidity (RH) environment, the test piece is repeatedly bent 90 times per minute.

The polyimide film of the second embodiment of the present invention is produced by thermally imidizing using a polyimide precursor resin having a specific structure in the first embodiment of the present invention. May be.
According to the first invention, as described above, the polyimide tends to have an irregular structure in the film, and the polyimide is not decomposed in the process of thermal imidization, and a specific high molecular weight is maintained. Therefore, it is possible to produce a polyimide film having sufficient transparency, suppressing a decrease in bending resistance, and further reducing a phase difference. Above all, by using the polyimide precursor resin having a specific structure, the polyimide film of the second embodiment of the present invention has a good balance of transparency, phase difference, elastic modulus and bending resistance. It is possible to achieve a polyimide film having a low phase difference, a high elastic modulus, and an improved bending resistance while having sufficient transparency.

1. 1. Polyimide resin The polyimide resin contained in the polyimide film of the second embodiment of the present invention has a structural unit represented by the general formula (1'), and in the general formula (1'), A is. It may contain at least a tetravalent group which is a residue of the acid dianhydride represented by the chemical formula (a-1), and may further have a structural unit represented by the general formula (2). It is a polyimide resin.

A, which is a residue of tetracarboxylic acid dianhydride in the structural unit represented by the general formula (1'), and B, which is a residue of diamine, are the polyimide precursor resin of one embodiment of the present invention. Similar to A, which is a residue of tetracarboxylic acid dianhydride in the structural unit represented by the general formula (1-1) or the general formula (1-2), and B, which is a residue of diamine. It's okay to have it.
Further, the structural unit represented by the general formula (2) may be the same as the structural unit represented by the general formula (2) in the polyimide precursor resin of one embodiment of the present invention.

In the general formula (1'), A contains at least a tetravalent group which is a residue of the acid dianhydride represented by the chemical formula (a-1).
The polyimide resin according to one embodiment of the present invention has the chemical formula (1') of 50% or more, 60% or more, and 70% or more with respect to all A in the structural unit represented by the general formula (1'). It is preferably a tetravalent group which is a residue of the acid dianhydride represented by a-1), and may be 100%.
On the other hand, the polyimide resin according to one embodiment of the present invention contains 50% or less, further 40% or less, and further 30% or less with respect to all A in the structural unit represented by the general formula (1'). It may be a residue of at least one tetracarboxylic dianhydride selected from the group consisting of the group A1 and the group A2, which is different from the acid dianhydride represented by the chemical formula (a-1).

The polyimide resin according to one embodiment of the present invention has 50% or more, more 60% or more, and further 70% or more with respect to all B in the structural unit represented by the general formula (1'). It is preferably a residue of at least one tetracarboxylic dianhydride selected from the group consisting of.
On the other hand, the polyimide resin according to one embodiment of the present invention is 50% or less, further 40% or less, and further 30% or less with respect to all B in the structural unit represented by the general formula (1'). It may be a residue of at least one tetracarboxylic dianhydride selected from the group consisting of group B2.

Even when the polyimide resin contains a polyimide structural unit different from the structural unit represented by the general formula (1'), the general polyimide structural unit of the polyimide resin used in the present invention is referred to. The total content of the structural units represented by the formula (1') is preferably 80 mol% or more, more preferably 90 mol% or more, further preferably 95 mol% or more, and 98 mol. % Or more is even more preferable.

Further, the total content ratio of the structural units represented by the general formula (2) is preferably 60 mol% or less, more preferably 40 mol% or less, with respect to all the structural units of the polyimide resin used in the present invention. Is more preferable.
That is, in the polyimide resin used in the present invention, the total content of dicarboxylic acid residues may be 0 mol%, but with respect to the total of all tetracarboxylic acid residues and all dicarboxylic acid residues. It is preferably 60 mol% or less, and more preferably 40 mol% or less.

Further, the polyimide resin used in the present invention may contain the polyimide resin as long as the effect of the present invention is not impaired. In the general formula (1'), A is another tetra different from the group A1 and the group A2. The said, wherein B represents a tetravalent group that is a residue of the carboxylic acid dianhydride, or B represents a divalent group that is a residue of another diamine different from said group B1 and said group B2. The structural unit different from the general formula (1') may be the same as that of the above-mentioned polyimide precursor resin. Even when such a structural unit different from the general formula (1') is contained, the total content ratio of the residues of other tetracarboxylic acid dianhydrides different from the group A1 and the group A2 is , 20 mol% or less, more preferably 10 mol% or less, still more preferably 5 mol% or less, based on the total of all tetracarboxylic acid residues and all dicarboxylic acid residues. It is more preferably 2 mol% or less.
Further, the total content ratio of the residues of other diamines different from the group B1 and the group B2 is preferably 20 mol% or less, more preferably 10 mol% or less, based on the total of all diamine residues. It is more preferably 5 mol% or less, and even more preferably 2 mol% or less.

In the polyimide resin used in the present invention, the total of the structural units represented by the general formula (1') and the structural units represented by the general formula (2) is 95% or more of the total structural units of the polyimide. It is preferably present, more preferably 98% or more, and even more preferably 100%.

The polyimide resin used in the present invention has a polystyrene-equivalent weight average molecular weight of gel permeation chromatography preferably 106,000 or more, more preferably 120,000 or more, still more preferably 150,000 or more, and is preferable. Is 1,000,000 or less, more preferably 500,000 or less, still more preferably 300,000 or less.
When the weight average molecular weight of the polyimide is at least the lower limit value, bending resistance tends to be good, which is preferable. On the other hand, when it is at least the above upper limit value, the viscosity of the varnish can be suppressed and the coating on the support can be easily performed, which is preferable.

The weight average molecular weight of the polyimide resin can be measured by gel permeation chromatography (GPC). Specifically, a polyimide resin is used as an N-methylpyrrolidone (NMP) solution having a concentration of 0.1% by mass, and a 30 mmol% LiBr-NMP solution having a water content of 500 ppm or less is used as a developing solvent. -8120, column used: GPC LF-804 manufactured by SHODEX), the sample injection amount is 50 μL, the solvent flow rate is 0.4 mL / min, and the measurement is performed at 37 ° C. The weight average molecular weight is determined based on a polystyrene standard sample having the same concentration as the sample.

In the polyimide resin used in the present invention, the ratio of the raw material composition can be confirmed and the content ratio (mol%) of each residue can be determined by the following method.
First, a sodium hydroxide solution prepared by mixing 2.0 g of sodium hydroxide, 25 mL of water, and 25 mL of methanol is prepared, and 200 mg of the resin is dissolved in 10 mL of the sodium hydroxide solution. Depolymerization of the polyimide resin is promoted by heating the solution in a pressure-resistant container at 250 ° C. for 1 hour. The obtained solution is extracted with chloroform and water, and the decomposition product (raw material monomer) is separated. The ratio of the raw material composition is measured by gas chromatography (HP6890 / HP5793 manufactured by Agilent Technologies) (the column uses "InertCap 5MS / Sil (30m x 250μm x 0.25μm, manufactured by GL Sciences)". The measurement condition is 50. Hold at ° C for 5 min, then raise to 320 ° C at 10 ° C / min and hold for 3 min.) The composition ratio of each raw material can be calculated from the area ratio of gas chromatography.
The content ratio (mol%) of each residue in the polyimide resin can also be obtained from the charging ratio of the raw materials at the time of resin production. Further, the structure of the polyimide resin can be obtained by using NMR, various mass spectrometry, elemental analysis, XPS / ESCA, TOF-SIMS and the like.

2. 2. Total light transmittance The polyimide film of one embodiment of the present invention has a total light transmittance of 85.0% in terms of a film thickness of 40 μm, as measured in accordance with JIS K7631-1 from the viewpoint of good transparency. That is all. The total light transmittance measured according to JIS K7361-1 of the polyimide film of one embodiment of the present invention is more preferably 87.0% or more, more preferably 89.0% or more in terms of a film thickness of 40 μm. It is more preferably 89.2% or more, and even more preferably 89.2% or more.

The total light transmittance measured according to JIS K7361-1 can be measured by, for example, a haze meter (for example, HM150 manufactured by Murakami Color Technology Laboratory). From the measured value of the total light transmittance of a certain thickness, the converted value of the total light transmittance of different thickness can be obtained by Lambertbert's law, and it can be used.
Specifically, according to Lambert-Beer's law, the transmittance T is
Log ₁₀ (1 / T) = kcb
It is represented by (k = substance-specific constant, c = concentration, b = optical path length).
In the case of the transmittance of the film, c is also a constant assuming that the density is constant even if the film thickness changes. Therefore, in the above equation, Log ₁₀ (1 / T) = fb using the constant f.
It can be expressed as (f = kc). Here, if the transmittance at a certain film thickness is known, the unique constant f of each substance can be obtained. Therefore, by substituting a constant unique to f and a target film thickness into b using the equation of T = 1/10 ^{f · b} , the transmittance at a desired film thickness can be obtained.

3. 3. Yellowness The polyimide film of one embodiment of the present invention is based on JIS K7373-2006 because it suppresses yellowish coloring, improves light transmission, and can be suitably used as a glass substitute material. The value (YI value / film thickness (μm)) obtained by dividing the calculated yellowness (YI value) by the film thickness (μm) of the polyimide film is 0.15 or less, and 0.13 or less. It is preferably 0.10 or less, and even more preferably 0.10 or less.
In the present invention, the value (YI value / film thickness (μm)) obtained by dividing the yellowness (YI value) by the film thickness (μm) of the polyimide film is below the decimal point in accordance with Rule B of JIS Z8401: 1999. The value is rounded to the second decimal place.

Further, in the polyimide film of one embodiment of the present invention, the yellowness (YI value) calculated in accordance with JIS K7373-2006 is calculated in accordance with JIS K7373-2006. However, it is preferably 10.0 or less in terms of a film thickness of 40 μm. Such a low degree of yellowness is preferable from the viewpoint that yellowish coloring is suppressed and light transmission is improved. The yellowness (YI value) calculated in accordance with JIS K7373-2006 is more preferably 5.0 or less, and further preferably 4.0 or less, in terms of a film thickness of 40 μm.
The yellowness (YI value) is assisted by a spectrophotometric method using an ultraviolet-visible near-infrared spectrophotometer (for example, JASCO Corporation V-7100) in accordance with the JIS K7373-2006. The tristimulus values X, Y, Z in the XYZ colorimetric system are obtained based on the transmittance measured at 1 nm intervals in the range of 250 nm or more and 800 nm or less using the Illuminant C and the two-degree field, and the X, Y are obtained. , Z can be calculated from the following formula.
YI = 100 (1.2769X-1.592Z) / Y
From the measured value of the yellowness of a certain thickness, the yellowness of a different thickness is the above-mentioned total for each transmittance at each wavelength measured at 1 nm intervals between 250 nm and 800 nm or less of a sample of a specific film thickness. Similar to the light transmittance, the converted value of each transmittance at each wavelength having a different thickness can be obtained by Lambertvale's law, and can be calculated and used based on the converted value.

4. Birefringence The polyimide film of one embodiment of the present invention can realize a low phase difference, and the birefringence in the thickness direction at a wavelength of 590 nm is less than 0.025.
Since it has such a birefringence, the polyimide film of this embodiment has reduced optical strain. The birefringence at the wavelength of 590 nm is preferably smaller, preferably 0.023 or less, more preferably 0.022 or less, and even more preferably 0.021 or less.
The birefringence in the thickness direction of the polyimide film of one embodiment of the present invention at a wavelength of 590 nm can be determined as follows.
First, the thickness direction retardation value (Rth) of the polyimide film is measured with light at 23 ° C. and a wavelength of 590 nm using a phase difference measuring device (for example, manufactured by Oji Measuring Instruments Co., Ltd., product name “KOBRA-WR”). do. For the thickness direction retardation value (Rth), the phase difference value incident at 0 degrees and the phase difference value incident at an angle of 40 degrees are measured, and the thickness direction retardation value Rth is calculated from these phase difference values. The retardation value of the oblique 40-degree incident is measured by injecting light having a wavelength of 590 nm onto the retardation film from a direction inclined by 40 degrees from the normal of the retardation 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.
The thickness direction retardation value is nx for the refractive index in the slow-phase axial direction (the direction in which the refractive index is maximized in the in-plane direction of the film) in the in-plane direction of the film, and the phase-advancing axial direction (the film surface) in the film surface. Calculated according to Rth [nm] = {(nx + ny) /2-nz} × d, where ny is the refractive index (in the direction in which the refractive index is minimized in the inward direction) and nz is the refractive index in the thickness direction of the film. Is to be done.
The in-plane retardation value (Re) at a wavelength of 590 nm is preferably 200 nm or less, more preferably 150 nm or less, further preferably 50 nm or less, still more preferably 30 nm or less. .. It is calculated according to Re [nm] = (nx-ny) × d.

5. Elastic modulus The polyimide film of one embodiment of the present invention is a tensile test in a tensile test in which a 10 mm × 150 mm test piece is measured at 25 ° C. in accordance with JIS K7127 with a tensile speed of 50 mm / min and a chuck distance of 100 mm. The elastic modulus is 4.0 GPa or more. As described above, when the tensile elastic modulus at 25 ° C. (room temperature) is high, sufficient surface hardness as a protective film can be maintained even at room temperature, and it can be used as a surface material or a base material. The tensile elastic modulus is more preferably 4.3 GPa or more. On the other hand, the tensile elastic modulus may be 15.0 GPa or less from the viewpoint of improving bending resistance.
The tensile elastic modulus was determined by cutting a test piece having a width of 10 mm and a length of 150 mm from a polyimide film using a tensile tester (for example, manufactured by Shimadzu Corporation: Autograph AG-X 1N, load cell: SBL-1KN) and at 25 ° C. The tensile speed can be measured as 50 mm / min, and the distance between chucks can be measured as 100 mm. The thickness of the polyimide film used to determine the tensile elastic modulus is preferably 40 μm ± 5 μm.

6. Dynamic bending test The polyimide film of one embodiment of the present invention has a bending count of 100,000 times or more and 11,000,000 times or more in the following dynamic bending test from the viewpoint of bending resistance. It is preferable, and more preferably 125,000 times or more.
(Dynamic bending test)
The method of the dynamic bending test will be described with reference to FIG.
Two movable metal plates 11 (100 mm × 30 mm) having a movable portion 11a and a non-movable portion 11b are prepared, and the two metal plates 11 are parallel so that the distance between the non-movable portions 11b is 60 mm. Place in. As shown in FIG. 1A, the movable portion 11a of the metal plate 11 is bent so as to be perpendicular to the non-movable portion 11b, and the polyimide film cut out on the movable portion 11a to a size of 20 mm × 100 mm is formed. The test piece 1 is placed, and both ends of the test piece 1 are fixed to the movable portion 11a with Kapton (registered trademark) tape so that the center of the test piece 1 is located at the center of the distance between the metal plates. Next, the movable portion 11a and the non-movable portion 11b are arranged in a straight line so as to be in the state shown in FIG. 1 (B), that is, the test piece 1 curved at the position of half of the long side is placed from both sides. It is sandwiched between the metal plates 11 and the metal plates 11 on both sides are arranged in parallel so that the distance between the metal plates 11 on both sides is 60 mm. In such a state and in a state where the metal plates on both sides are arranged in parallel so that the distance between the metal plates 11 on both sides is 2.5 mm as shown in FIG. 1 (C), the temperature is 25 ° C. and 60%. In a relative humidity (RH) environment, the bending is repeated 90 times per minute. As the test jig, a constant temperature and humidity constant humidity test system (manufactured by Yuasa System Equipment Co., Ltd., surface-shaped no-load U-shaped expansion and contraction test jig DMX-FS) can be used.
Measure the number of bends (number of breaks) before breaking.

7. Pencil hardness The polyimide film of one embodiment of the present invention preferably has a surface pencil hardness of B or higher, preferably HB or higher, in the pencil hardness test specified in JIS 5600-5-4 (1999). More preferably, it is more preferably F or more.
The pencil hardness of the polyimide film is determined by adjusting the humidity of the measurement sample for 2 hours under the 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. It can be performed by performing a pencil hardness test (0.98 N load) specified in (1999) on the film surface and evaluating the highest pencil hardness that does not damage the film. As the testing machine, for example, a pencil scratch coating film hardness testing machine manufactured by Toyo Seiki Co., Ltd. can be used.

8. Film Thickness The thickness of the polyimide film according to the embodiment of the present invention may be appropriately selected depending on the intended use, but may be 1 μm or more, preferably 5 μm or more, and preferably 10 μm or more. , 20 μm or more. On the other hand, it is preferably 300 μm or less, more preferably 200 μm or less, further preferably 150 μm or less, and further preferably 100 μm or less.
If the thickness is thin, the strength is lowered, and if the thickness is thick, the difference between the inner diameter and the outer diameter at the time of bending becomes large, and the load on the film becomes large, so that the bending resistance may decrease.

9. Surface treatment Further, the polyimide film of one embodiment 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.

10. Uses of Polyimide Film The use of the polyimide film of the present invention is not particularly limited, but it has a low phase difference, a high elastic modulus, and an improved bending resistance while having sufficient transparency. It can be used as a member such as a base material or a surface material for which a glass product such as a thin plate glass has been used.
Specifically, the polyimide film of the present invention includes, for example, a thin and bendable flexible type organic EL display, a mobile terminal such as a smartphone or a wristwatch type terminal, a display device inside an automobile, a flexible panel used for a wristwatch, or the like. It can be suitably used as a base material or a surface material for a flexible display. Further, the polyimide film of the present invention is a member for an image display device such as a liquid crystal display device or an organic EL display device, a member for a touch panel, a flexible printed substrate, a member for a solar cell panel such as a surface protective film or a substrate material, and an optical waveguide. It can also be applied to members and other semiconductor-related members.

V. Laminate The laminate of the second embodiment of the present invention contains the polyimide film of the second embodiment of the present invention and at least one polymer of a radically polymerizable compound and a cationically polymerizable compound. It is a laminate having a hard coat layer.
Here, the "hard coat layer" is a layer for improving the surface hardness, and specifically, the hardness of "H" or higher in the pencil hardness test specified in JIS 5600-5-4 (1999). Indicates something that indicates.
Since the laminate of the second embodiment of the present invention uses the polyimide film of the second embodiment of the present invention, it has sufficient transparency, low phase difference, and high. It is a film having an elastic modulus and improved bending resistance, and further has a hard coat layer, so that the surface hardness is further improved.

1. 1. Polyimide film As the polyimide film used for the laminate of the second embodiment of the present invention, the same polyimide film as the above-mentioned second polyimide film of the first embodiment of the present invention can be used. The explanation is omitted.

2. 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. If necessary, an optional additive component may be contained as long as the effect of the present invention is not impaired.

(At least one polymer of a radically polymerizable compound and a cationically polymerizable compound)
For the polymer of at least one of the radically polymerizable compound and the cationically polymerizable compound, at least one of the radically polymerizable compound and the cationically polymerizable compound is polymerized by a known method using a polymerization initiator, if necessary. Can be obtained by

The radically polymerizable compound is a compound having a radically polymerizable group. The radically polymerizable group contained in the radically polymerizable compound may be any functional group capable of causing a radical polymerization reaction, and is not particularly limited, and examples thereof include a group containing a carbon-carbon unsaturated double bond. Specific examples thereof 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 from each other.

The number of radically polymerizable groups contained in one molecule of the radically polymerizable compound is preferably two or more, and more preferably three or more, from the viewpoint of improving the hardness of the hard coat layer.
As the radically polymerizable compound, a compound having a (meth) acryloyl group is preferable from the viewpoint of high reactivity, and for example, urethane (meth) acrylate, polyester (meth) acrylate, epoxy (meth) acrylate, and melamine. Polyfunctional (meth) acrylates having several (meth) acryloyl groups in molecules called (meth) acrylates, polyfluoroalkyl (meth) acrylates, silicone (meth) acrylates, etc. and having a molecular weight of hundreds to thousands. Monomers and oligomers can be preferably used, and polyfunctional (meth) acrylate polymers having two or more (meth) acryloyl groups in the side chains of the acrylate polymer can also be preferably used. Among them, a polyfunctional (meth) acrylate monomer having two or more (meth) acryloyl groups in one molecule can be preferably used. By including the polymer of the polyfunctional (meth) acrylate monomer in the hard coat layer, the hardness of the hard coat layer can be improved, and the adhesion can be further improved. Further, a polyfunctional (meth) acrylate oligomer or polymer having two or more (meth) acryloyl groups in one molecule can also be preferably used. When the hard coat layer contains a polymer of the polyfunctional (meth) acrylate oligomer or polymer, the hardness and bending resistance of the hard coat layer can be improved, and the adhesion can be further improved.
In addition, in this specification, (meth) acryloyl represents each of acryloyl and methacryloyl, and (meth) acrylate represents each of acrylate and methacrylate.

Examples of the polyfunctional (meth) acrylate monomer include trimethyl propantri (meth) acrylate, tripropylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, and pentaerythritol tri. (Meta) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, trimethyl propantri (meth) Acrylate, ditrimethylol propanetetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, tripentaerythritol octa (meth) acrylate, tetrapentaerythritol deca (meth) acrylate, isocyanuric acid tri (meth) acrylate, isocyanuric acid di ( Meta) acrylate, polyester tri (meth) acrylate, polyester di (meth) acrylate, bisphenol di (meth) acrylate, diglycerin tetra (meth) acrylate, adamantyldi (meth) acrylate, isoboroldi (meth) acrylate, dicyclopentanedi Examples thereof include (meth) acrylate, tricyclodecandi (meth) acrylate, ditrimethylolpropanetetra (meth) acrylate, and those modified with PO, EO, caprolactone and the like. Among them, those having 3 or more and 6 or less (meth) acryloyl groups in one molecule are preferable from the viewpoint of high reactivity, improvement of the hardness of the hard coat layer, and adhesion, for example, pentaerythritol. Triacrylate (PETA), Dipentaerythritol Hexaacrylate (DPHA), Pentaerythritol Tetraacrylate (PETTA), Dipentaerythritol Pentaacrylate (DPPA), Trimethylol Propantri (meth) Acrylate, Trypentaerythritol Octa (Meta) Acrylate, Tetrapentaerythritol deca (meth) acrylate and the like can be preferably used, and in particular, at least one selected from pentaerythritol tri (meth) acrylate and dipentaerythritol penta (meth) acrylate is preferable.

In the present invention, the radically polymerizable compound may contain a monofunctional (meth) acrylate monomer in order to adjust the hardness, the viscosity of the composition for a hard coat layer, improve the adhesion, and the like. Examples of the monofunctional (meth) acrylate monomer include hydroxyethyl acrylate (HEA), glycidyl methacrylate, methoxypolyethylene glycol (meth) acrylate, isostearyl (meth) acrylate, 2-acryloyloxyethyl succinate, acryloyl morpholine, and N. -Acryloyloxyethyl hexahydrophthalimide, cyclohexyl acrylate, tetrahydrofuryl acrylate, isobornyl acrylate, phenoxyethyl acrylate, adamantyl acrylate and the like can be mentioned.

The cationically polymerizable compound is a compound having a cationically polymerizable group. The cationically polymerizable group contained in the cationically polymerizable compound may be any functional group capable of causing a cationically polymerizable reaction, and is not particularly limited, and examples thereof include an epoxy group, an oxetanyl group, and a vinyl ether group. When the cationically polymerizable compound has two or more cationically polymerizable groups, the cationically polymerizable groups may be the same or different from each other.

The number of cationically polymerizable groups contained in one molecule of the cationically polymerizable compound is preferably two or more, and more preferably three or more, from the viewpoint of improving the hardness of the hard coat layer.
Further, as the cationically polymerizable compound, a compound having at least one of an epoxy group and an oxetanyl group as a cationically polymerizable group is preferable, and at least one of an epoxy group and an oxetanyl group is contained in one molecule. Compounds are more preferred. A cyclic ether group such as an epoxy group or an oxetanyl group is preferable because the shrinkage associated with the polymerization reaction is small. Further, among the cyclic ether groups, compounds having an epoxy group are easily available, compounds having various structures are easily available, the durability of the obtained hard coat layer is not adversely affected, and compatibility with radically polymerizable compounds is easily controlled. There is an advantage. Further, among the cyclic ether groups, the oxetanyl group has a higher degree of polymerization than the epoxy group and has low toxicity, and when the obtained hard coat layer is combined with a compound having an epoxy group, it is contained in the coating film. There are advantages such as increasing the network formation rate obtained from the cationically polymerizable compound and forming an independent network without leaving an unreacted monomer in the film even in a region mixed with the radically polymerizable compound.

Examples of the cationically polymerizable compound having an epoxy group include polyglycidyl ether of a polyhydric alcohol having an alicyclic ring, or a cyclohexene ring or cyclopentene ring-containing compound with an appropriate oxidizing agent such as hydrogen peroxide or peracid. Alicyclic epoxy resin obtained by epoxidation; polyglycidyl ether of aliphatic polyhydric alcohol or its alkylene oxide adduct, polyglycidyl ester of aliphatic long chain polybasic acid, homopolymer of glycidyl (meth) acrylate, An aliphatic epoxy resin such as a copolymer; a glycidyl ether produced by reacting bisphenols such as bisphenol A, bisphenol F and hydrogenated bisphenol A, or derivatives such as alkylene oxide adducts and caprolactone adducts thereof with epichlorohydrin. And novolak epoxy resin and the like, and examples thereof include glycidyl ether type epoxy resin derived from bisphenols.

Examples of the alicyclic epoxy resin include 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, bis-3,4-epoxycyclohexylmethyl adipate and the like.

Examples of the glycidyl ether type epoxy resin include sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaeryth little polyglycidyl ether, diglycerol polyglycidyl ether, glycerol polyglycidyl ether, trimethylolpropane polyglycidyl ether, and reso. Lutinol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6 hexanediol diglycidyl ether, hydrodibisphenol A diglycidyl ether, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol glycidyl ether, polypropylene glycol glycidyl ether , Allyl glycidyl ether, 2-ethylhexyl glycidyl ether, phenyl glycidyl ether, phenol glycidyl ether, butyl phenyl glycidyl ether, diglycidyl phthalate, hydroquinone diglycidyl ether, diglycidyl terephthalate, glycidyl phthalimide, dibromophenyl glycidyl ether, dibromoneopentyl glycol di Examples include glycidyl ether and the like.
Further, other commercially available epoxy resins may be used.

Examples of the cationically polymerizable compound having an oxetanyl group include 3-ethyl-3-hydroxymethyloxetane, 1,4-bis-3-ethyloxetane-3-ylmethoxymethylbenzene, and bis-1-ethyl-3-oxetanyl. Examples thereof include methyl ether, 3-ethyl-3-2-ethylhexyloxymethyloxetane, 3-ethyl-3-phenoxymethyloxetane and the like.

(Polymer initiator)
The polymer of at least one of the radically polymerizable compound and the cationically polymerizable compound contained in the hard coat layer used in the present invention is required for, for example, at least one of the radically polymerizable compound and the cationically polymerizable compound. It can be obtained by adding a polymerization initiator and carrying out a polymerization reaction by a known method.

As the polymerization initiator, a radical polymerization initiator, a cationic polymerization initiator, a radical, a cationic polymerization initiator 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 cation polymerization.

The radical polymerization initiator may be any kind as long as it can release a substance that initiates radical polymerization by at least one of light irradiation and heating. For example, examples of the photoradical polymerization initiator include imidazole derivatives, bisimidazole derivatives, N-arylglycine derivatives, organic azide compounds, titanocenes, aluminate complexes, organic peroxides, N-alkoxypyridinium salts, thioxanthone derivatives and the like. More specifically, 1,3-di (tert-butyldioxycarbonyl) benzophenone, 3,3', 4,4'-tetrakis (tert-butyldioxycarbonyl) benzophenone, 3-phenyl-5-. Isooxazolone, 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-cyclopentadiene-1-yl) -bis (2,6-difluoro-3- (1H-pyrrole-1-yl) ) -Phenyl) Titanium) (trade name: Irgacure 784, manufactured by Ciba Japan Co., Ltd.), etc., but is not limited thereto.
In addition to the above, commercially available products can be used by appropriately selecting them.

Further, the cationic polymerization initiator may be any material as long as it can release a substance that initiates cationic polymerization by at least one of light irradiation and heating. Examples of the cationic polymerization initiator include sulfonic acid ester, imide sulfonate, dialkyl-4-hydroxysulfonium salt, aryl sulfonic acid-p-nitrobenzyl ester, silanol-aluminum complex, (η ⁶ -benzene) (η ⁵ -cyclopentadi). Enyl) iron (II) and the like are exemplified, and more specific examples thereof include, but are not limited to, benzointosylate, 2,5-dinitrobenzyltosylate, N-tosiphthalateimide and the like.

Examples of those used as both the radical polymerization initiator and the cationic polymerization initiator include aromatic iodonium salts, aromatic sulfonium salts, aromatic diazonium salts, aromatic phosphonium salts, triazine compounds, and iron arene complexes. However, it is not limited to these.

(Optional additive component)
The hard coat layer used in the present invention may further contain an optional additive component, if necessary, in addition to the polymer.
The optional additive component is appropriately selected depending on the function to be imparted to the hard coat layer, and is not particularly limited, but for example, an inorganic or organic fine particle for adjusting the hardness and the refractive index, an ultraviolet absorber, an infrared absorber, and the like. Anti-glare agents, antifouling agents, antistatic agents, etc., as well as leveling agents, surfactants, anti-slip agents, various sensitizers, flame-retardant agents, adhesion-imparting agents, polymerization inhibitors, antioxidants, surface modifications. It may contain a pledge agent or the like.

The polymer of at least one of the radically polymerizable compound and the cationically polymerizable compound contained in the hard coat layer used in the present invention includes a Fourier transform infrared spectrophotometer (FTIR) and a thermal decomposition gas chromatograph device (GC). -MS) and the decomposition products of the polymer can be analyzed using a combination of high-speed liquid chromatography, gas chromatograph mass spectrometer, NMR, elemental analysis, XPS / ESCA, TOF-SIMS and the like.

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

The overall thickness of the laminate of the present invention may be appropriately selected depending on the intended use, but is preferably 10 μm or more, and more preferably 40 μm or more from the viewpoint of strength. On the other hand, from the viewpoint of bending resistance, it is preferably 300 μm or less, and more preferably 250 μm or less.
Further, in the laminated body of the present invention, the thickness of each hardcoat layer may be appropriately selected depending on the intended use, but is preferably 2 μm or more and 80 μm or less, and more preferably 3 μm or more and 50 μm or less. Further, from the viewpoint of curl prevention, a hard coat layer may be formed on both sides of the polyimide film.

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

From the viewpoint of good transparency, the laminated body of one embodiment of the present invention has a total light transmittance of 85.0% or more in terms of a film thickness of 50 μm, which is measured according to JIS K7361-1. The total light transmittance measured according to JIS K7361-1 of the laminate of one embodiment of the present invention is more preferably 87.0% or more, more preferably 89.0% or more in terms of a film thickness of 40 μm. It is more preferably 89.3% or more, and even more preferably 89.3% or more.
The total light transmittance of the laminate of the present invention can be measured in the same manner as the total light transmittance measured in accordance with JIS K7361-1 of the polyimide film.

The laminate of one embodiment of the present invention is calculated in accordance with JIS K7373-2006 because yellowish coloring is suppressed, light transmission is improved, and it can be suitably used as a glass substitute material. The value (YI value / film thickness (μm)) obtained by dividing the yellowness (YI value) by the total film thickness (μm) of the polyimide film and the hard coat layer is 0.15 or less, and is 0.10 or less. Is more preferable, and 0.08 or less is even more preferable.
In the present invention, the value (YI value / film thickness (μm)) obtained by dividing the yellowness (YI value) by the total film thickness (μm) of the polyimide film and the hard coat layer is determined by Rule B of JIS Z8401: 1999. Therefore, the value is rounded to the second decimal place.
The yellowness (YI value) of the laminate of the present invention can be measured in the same manner as the yellowness (YI value) calculated in accordance with JIS K7373-2006 of the polyimide film.

Further, in the laminated body of one embodiment of the present invention, the yellowness (YI value) calculated in accordance with JIS K7373-2006 is calculated in accordance with JIS K7373-2006. However, it is preferably 10.0 or less in terms of a film thickness of 50 μm. Such a low degree of yellowness is preferable from the viewpoint that yellowish coloring is suppressed and light transmission is improved. The yellowness (YI value) calculated in accordance with JIS K7373-2006 is more preferably 5.0 or less, and further preferably 4.0 or less, in terms of a film thickness of 50 μm.

The laminate of one embodiment of the present invention can realize a low phase difference, and the birefringence in the thickness direction at a wavelength of 590 nm is less than 0.025.
Since it has such a birefringence index, the laminated body of this embodiment has reduced optical strain. The birefringence at the wavelength of 590 nm is preferably smaller, preferably 0.023 or less, more preferably 0.022 or less, and even more preferably 0.021 or less.
The birefringence in the thickness direction of the laminate of the present invention at a wavelength of 590 nm can be measured in the same manner as the birefringence in the thickness direction of the polyimide film at a wavelength of 590 nm.

The laminated body of one embodiment of the present invention is a tensile elastic modulus in a tensile test in which a test piece of 10 mm × 150 mm is measured at 25 ° C. in accordance with JIS K7127, with a tensile speed of 50 mm / min and a distance between chucks of 100 mm. Is 4.0 GPa or more. As described above, when the tensile elastic modulus at 25 ° C. (room temperature) is high, sufficient surface hardness as a protective film can be maintained even at room temperature, and it can be used as a surface material or a base material. The tensile elastic modulus is more preferably 4.3 GPa or more. On the other hand, the tensile elastic modulus may be 15.0 GPa or less from the viewpoint of improving bending resistance.
The tensile elastic modulus of the laminate of the present invention can be measured in the same manner as the tensile elastic modulus of the polyimide film.

From the viewpoint of bending resistance, the laminated body of one embodiment of the present invention has a bending frequency of 100,000 times or more, preferably 110,000 times or more, and preferably 125,000 times or more in the dynamic bending test. Is more preferable.
The dynamic bending test of the laminate of the present invention can be measured in the same manner as the dynamic bending test of the polyimide film.

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

VI. Display member The display member of one embodiment of the present invention includes the polyimide film of one embodiment of the present invention described above, or the laminate of one embodiment of the present invention.
Examples of the display member according to one embodiment of the present invention include a display surface material and a display base material.
The display member of one embodiment of the present invention may be the polyimide film of one embodiment of the present invention described above, or the laminated body of one embodiment of the present invention.

The display member of one embodiment of the present invention is used, for example, as a surface material for a display by arranging it so as to be located on the surface of various displays. Similar to the polyimide film of the present invention and the laminate of the present invention described above, the display member of one embodiment of the present invention has sufficient transparency, but has improved low phase difference and high elastic modulus. Since it has bending resistance, it can be particularly preferably used for flexible displays.

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

When the display member of one embodiment of the present invention is the laminate of one embodiment of the present invention, the surface that becomes the outermost surface after arranging the laminate on the surface of the display is the surface on the polyimide film side. It may be the surface on the hard coat layer side. Above all, it is preferable to arrange the display member of the present invention so that the surface on the hard coat layer side becomes the surface on the front side. Further, the display member of one embodiment of the present invention may have a fingerprint adhesion prevention layer on the outermost surface.

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

VII. Touch panel member The touch panel member of one embodiment of the present invention includes the polyimide film of one embodiment of the present invention described above or the laminate of one embodiment of the present invention described above.
A transparent electrode composed of a plurality of conductive portions arranged on one surface side of the polyimide film or the laminate,
It has a plurality of take-out wires that are electrically connected on at least one side of the end of the conductive portion.

Since the touch panel member of one embodiment of the present invention includes the polyimide film of one embodiment of the present invention or the laminated body described above, the touch panel member has sufficient transparency, low phase difference, and high. Since it has an elastic modulus and improved bending resistance, it can be particularly preferably used for a flexible display and has excellent optical characteristics.
The laminate of the present invention used for the touch panel member of one embodiment of the present invention is a hard coat containing at least one polymer of a radically polymerizable compound and a cationically polymerizable compound adjacent to both sides of the polyimide film. It preferably has a layer.
Further, the touch panel member of one embodiment 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 laminated body.
The touch panel member of one embodiment of the present invention can be arranged and used, for example, so as to be located on the surface of various displays. Further, the touch panel member of the present invention and the polyimide film or laminate of one embodiment of the present invention as a surface material can be arranged and used in this order on the surface of various displays.

Hereinafter, the touch panel member of one embodiment of the present invention will be described with an example using the above-mentioned laminate of one embodiment of the present invention, but instead of the above-mentioned laminate of the present invention, the above-mentioned polyimide of the present invention will be described. Films can be used as well.
FIG. 2 is a schematic plan view of one surface of an example of the touch panel member according to the embodiment of the present invention, and FIG. 3 is a schematic plan view of the other surface of the touch panel member shown in FIG. 2. FIG. Is a cross-sectional view taken along the line AA'of the touch panel member shown in FIGS. 2 and 3. The touch panel member 20 shown in FIGS. 2, 3 and 4 has a laminated body 10 of the present invention, a first transparent electrode 4 arranged in contact with one surface of the laminated body 10, and the other of the laminated body 10. It is provided with a second transparent electrode 5 arranged in contact with the surface of the above. In the first transparent electrode 4, a plurality of first conductive portions 41, which are strip-shaped electrode pieces extending so as to extend in the x-axis direction, are arranged at predetermined intervals. A first take-out wire 7 electrically connected to the first conductive portion 41 is connected to the first conductive portion 41 at any one of its longitudinal end portions. A first terminal 71 for electrically connecting to an external circuit may be provided at the end of the first take-out wire 7 extending to the end edge 21 of the laminated body 10. The first conductive portion 41 and the first take-out wire 7 are generally connected in an inactive 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 take-out wire 7, for example, as shown in FIG. 2, a connection structure in which the connecting portion 24 is interposed can be adopted. Specifically, the connecting portion 24 can be formed by extending a layer of the conductive material from the longitudinal end portion of the first conductive portion 41 to a predetermined position in the inactive area 23. Further, by superimposing at least a part of the first take-out wire 7 on the connection portion 24, a connection structure between the first conductive portion 41 and the first take-out wire 7 can be formed.
The connection between the first conductive portion 41 and the first take-out wire 7 is not limited to the structure forming the connecting portion 24 as shown in FIG. For example, although not shown, the longitudinal end of the first conductive portion 41 is extended to the inactive area 23, and the first conductive portion 41 is extended to the inactive area 23 in the inactive area 23. The two may be electrically connected by riding the first take-out line 7 on the end portion of the above.
Note that FIG. 2 shows a form in which either one of the longitudinal end portions of the first conductive portion 41 is connected to the first take-out wire 7, but in the present invention, one first conductive portion is shown. The first take-out wire 7 may be electrically connected to both ends of the portion 41 in the longitudinal direction.

As shown in FIG. 3, the touch panel member 20 includes a second transparent electrode 5 arranged in contact with the other surface of the laminated body 10. In the second transparent electrode 5, a second conductive portion 51, which is a plurality of strip-shaped electrode pieces extending so as to extend in the y-axis direction, is arranged at a predetermined interval in the x-axis direction. There is.
A second take-out wire 8 electrically connected to the second conductive portion 51 is connected to the second conductive portion 51 at one of its longitudinal end portions.
The second take-out line 8 extends to a position of the end edge of the laminated body 10 that does not overlap with the first terminal 71 on the end edge 21 on which the above-mentioned first take-out line 7 is extended. ..
A second terminal 81 for electrically connecting to an external circuit may be provided at the end of the second take-out wire 8 extending to the end edge 21 of the laminated body 10.
As for the electrical connection between the second conductive portion 51 and the second take-out wire 8, the same form as the electrical connection between the first take-out wire 7 and the first conductive portion 41 can be applied. ..

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

As the conductive portion included in the touch panel member according to the first embodiment of the present invention, a touch panel member constituting a transparent electrode can be appropriately selected and applied, and the pattern of the conductive portion is as shown in FIGS. 2 and 3. Not limited. For example, by the capacitance method, a pattern of a transparent electrode capable of detecting a change in electric capacity due to contact with a finger or the like or a state close to contact can be appropriately selected and applied.
The material of the conductive portion is preferably a light-transmitting material, and for example, an indium oxide-based transparent electrode material containing indium tin oxide (ITO), indium oxide, indium zinc oxide (IZO), or the like as a main component. , Transparent conductive film containing tin oxide (SnO ₂ ), zinc oxide (ZnO) and the like as main constituents, conductive polymer compounds such as polyaniline and polyacetylene, and the like, but the present invention is not limited thereto. Further, the first conductive portion 41 and the second conductive portion 51 may be formed by using the same kind of conductive materials as each other, or may be formed by using different materials. In particular, it is preferable to form the first conductive portion 41 and the second conductive portion 51 using the same kind of conductive material 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, for example, a photolithography method, it can generally be formed to be about 10 nm to 500 nm.

The conductive material constituting the take-out wire included in the touch panel member according to the first embodiment of the present invention may or may not have light transmission. In general, the take-out wire can be formed by using a metal material such as silver or copper having high conductivity. Specific examples thereof include elemental metals, composites of metals, composites of metals and metal compounds, and metal alloys. Examples of the simple substance of metal include silver, copper, gold, chromium, platinum, and simple substance of aluminum. As the metal complex, MAM (three-layer structure of molybdenum, aluminum, and molybdenum) and the like can be exemplified. Examples of the composite of the metal and the metal compound include a laminate of chromium oxide and chromium. As the metal alloy, silver alloys and copper alloys are widely used. Further, as the metal alloy, APC (alloy of silver, palladium and copper) and the like can be exemplified. Further, the take-out wire may appropriately contain a resin component in the above-mentioned metal material.
In the touch panel member of one embodiment of the present invention, the terminal provided at the end of the take-out wire can be formed, for example, by using the same material as the take-out wire.
The thickness and width of the take-out line are not particularly limited, but when the take-out line is formed by, for example, a photolithography method, the thickness is generally formed to be about 10 nm to 1000 nm, and the width dimension is from 5 μm. It is formed to about 200 μm. On the other hand, when the take-out line is formed by printing such as screen printing, the thickness is generally formed to be about 5 μm to 20 μm, and the width dimension is formed to be about 20 μm to 300 μm.

The touch panel member of one embodiment of the present invention is not limited to the embodiments shown in FIGS. 2 to 4, and for example, a first transparent electrode and a second transparent electrode are laminated on separate laminated bodies. It may be configured to be.
5 and 6 are schematic plan views showing an example of a conductive member provided with the laminate of the present invention, respectively. The first conductive member 201 shown in FIG. 5 has a laminated body 10 of the present invention and a first transparent electrode 4 arranged in contact with one surface of the laminated body 10. The transparent electrode 4 has a plurality of first conductive portions 41. The second conductive member 202 shown in FIG. 6 has a laminated body 10'of the present invention and a second transparent electrode 5 arranged in contact with one surface of the laminated body 10'. The second transparent electrode 5 has a plurality of second conductive portions 51.
FIG. 7 is a schematic cross-sectional view showing another example of the touch panel member according to the embodiment of the present invention, and the touch panel member 20'shown in FIG. 7 has the first conductive member 201 shown in FIG. 5 and FIG. The second conductive member 202 shown in the above is provided. In the touch panel member 20', the surface of the first conductive member 201 not having the first transparent electrode 4 and the surface of the second conductive member 202 having the transparent electrode 5 are interposed via the adhesive layer 6. It is pasted together. In the present invention, for example, an adhesive layer for adhering the laminate of one embodiment of the present invention and the touch panel member of the first embodiment of the present invention, and an adhesive layer for adhering the touch panel members of the present invention to each other. As the adhesive layer for adhering the touch panel member of the present invention to the display device or the like, a conventionally known adhesive layer used for the optical member can be appropriately selected and used. In the conductive member used for the touch panel member of the present invention, the configuration and material of the transparent electrode, the take-out wire and the terminal may be the same as those of the transparent electrode, the take-out wire and the terminal used for the touch panel member of the present invention described above. can.

VIII. Liquid crystal display device The liquid crystal display device of one embodiment of the present invention is the polyimide film of one embodiment of the present invention described above, or the laminate of the above-mentioned one embodiment of the present invention, and the polyimide film or the laminate. It has a liquid crystal display unit having a liquid crystal layer between facing substrates, which is arranged on one surface side.

Since the liquid crystal display device of one embodiment of the present invention includes the polyimide film or laminate of the above-mentioned one embodiment of the present invention, it has sufficient transparency, low phase difference, and high. It has elastic modulus and improved bending resistance, can be used particularly preferably for flexible displays, and has excellent optical characteristics.
The laminate of one embodiment of the present invention used in the liquid crystal display device of one embodiment of the present invention is adjacent to both sides of the polyimide film and is a polymer of at least one of a radically polymerizable compound and a cationically polymerizable compound. It is preferable to have a hard coat layer containing.
Further, the liquid crystal display device according to the embodiment of the present invention may include the touch panel member according to the embodiment of the present invention described above.
Further, the opposed substrate of the liquid crystal display device according to the first embodiment of the present invention may include the polyimide film or the laminate according to the first embodiment of the present invention.

Hereinafter, the liquid crystal display device according to the first embodiment of the present invention will be described with an example using the above-mentioned laminate of the first embodiment of the present invention, but instead of the above-mentioned laminate of the first embodiment of the present invention, the above-mentioned The polyimide film of one embodiment of the present invention can also be used in the same manner.
FIG. 8 is a schematic cross-sectional view showing an example of the liquid crystal display device according to the embodiment of the present invention. The liquid crystal display device 100 shown in FIG. 8 is provided with a first transparent electrode 4 on one surface of the laminate 10 of one embodiment of the present invention and the laminate 10'of one embodiment of the present invention, and the other. It has a touch panel member 20 having a second transparent electrode 5 on the surface, and a liquid crystal display unit 30. In the liquid crystal display device 100, the laminated body 10 is used as a surface material, and the laminated body 10 and the touch panel member 20 are bonded to each other via an adhesive layer 6.

The liquid crystal display unit used in the liquid crystal display device of one embodiment of the present invention has a liquid crystal layer formed between the substrates arranged so as to face each other, and has a configuration used in a conventionally known liquid crystal display device. Can be adopted.
The drive method of the liquid crystal display device according to the first embodiment of the present invention is not particularly limited, and a drive method generally used for a liquid crystal display device can be adopted. For example, a TN method, an IPS method, or an OCB method can be adopted. , And the MVA method and the like.
The facing substrate used in the liquid crystal display device according to the first embodiment of the present invention can be appropriately selected and used according to the drive method of the liquid crystal display device and the like, and the polyimide film or the laminate according to the first embodiment of the present invention can be used. You may use what is provided.
As the liquid crystal constituting the liquid crystal layer, various liquid crystals having different dielectric anisotropy and a mixture 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 producing a liquid crystal cell can be used, and examples thereof include a vacuum injection method and a liquid crystal dropping method. After forming the liquid crystal layer by the above method, the enclosed liquid crystal can be oriented by slowly cooling the liquid crystal cell to room temperature.
In the liquid crystal display device of one embodiment of the present invention, a colored layer of a plurality of colors and a light-shielding portion for defining pixels may be further provided between the substrates arranged to face each other. Further, the liquid crystal display unit may have a backlight unit having a light emitting element or a phosphor at a position opposite to the side where the touch panel member is located on the outside of the substrate arranged so as to face each other. Further, a polarizing plate may be provided on the outer surface of the substrates arranged so as to face each other.

FIG. 9 is a schematic cross-sectional view showing another example of the liquid crystal display device according to the embodiment of the present invention. The liquid crystal display device 200 shown in FIG. 9 has a first conductive body having a first transparent electrode 4 on one surface of the laminated body 10 of one embodiment of the present invention and the laminated body 10'of one embodiment of the present invention. A touch panel member 20'having a sex member 201 and a second conductive member 202 provided with a second transparent electrode 5 on one surface of the laminate 10 "of one embodiment of the present invention, and a liquid crystal display unit 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 to each other via the adhesive layer 6. The configuration of the touch panel member 20'can be, for example, the same as the configuration of the touch panel member 20'shown in FIG. 7. As the conductive member used in the liquid crystal display device of one embodiment of the present invention, the conductive member is used. The same conductive member as that used for the touch panel member according to the embodiment of the present invention can be used.

IX. Organic electroluminescence display device The organic electroluminescence display device of one embodiment of the present invention is the polyimide film of one embodiment of the present invention described above, or the above-mentioned laminate of one embodiment of the present invention and the polyimide film, or the polyimide film. It has an organic electroluminescence display unit having an organic electroluminescence layer between facing substrates arranged on one surface side of the laminate.

Since the organic electroluminescence display device of one embodiment of the present invention includes the polyimide film or laminate of one embodiment of the present invention described above, it has sufficient transparency and a low phase difference. Since it has a high elastic modulus and improved bending resistance, it can be particularly preferably used for a flexible display and has excellent optical characteristics.
The laminate of one embodiment of the present invention used in the organic electroluminescence display device of one embodiment of the present invention is adjacent to both sides of the polyimide film and is at least one of a radically polymerizable compound and a cationically polymerizable compound. It preferably has a hard coat layer containing a polymer.
Further, the organic electroluminescence display device according to the embodiment of the present invention may include the touch panel member according to the embodiment of the present invention described above.
Further, the facing substrate included in the organic electroluminescence display device according to the embodiment of the present invention may include the polyimide film or the laminate according to the embodiment of the present invention.

FIG. 10 is a schematic cross-sectional view showing an example of an organic electroluminescence display device according to an embodiment of the present invention. The organic electroluminescence display device 300 shown in FIG. 10 includes a first transparent electrode 4 on one surface of the laminate 10 of one embodiment of the present invention and the laminate 10'of one embodiment of the present invention. It has a touch panel member 20 having a second transparent electrode 5 on one surface, and an organic electroluminescence display unit 40. In the organic electroluminescence display device 300, the laminated body 10 is used as a surface material, and the laminated body 10 and the touch panel member 20 are bonded to each other via an adhesive layer 6.

The organic electroluminescence display unit (organic EL display unit) used in the organic electroluminescence display device (organic EL display device) according to the first embodiment of the present invention is an organic electroluminescence layer (organic electroluminescence layer) formed between substrates arranged opposite to each other. It has an organic EL layer), and a configuration used in a conventionally known organic EL display device can be adopted.
The organic EL display unit further includes a support substrate, an organic EL element including an 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 be any one having at least an organic EL light emitting layer, and for example, from the anode layer side, a hole injection layer, a hole transport layer, an organic EL light emitting layer, an electron transport layer, and an electron injection. Those having a structure in which the layers are laminated in this order can be used.
The organic EL display device of the present invention can be applied to, for example, both a passive drive type organic EL display and an active drive type organic EL display. As the facing substrate used in the organic EL display device of the present invention, it can be appropriately selected and used according to the driving method of the organic EL display device and the like, 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 according to the embodiment of the present invention. The organic electroluminescence display device 400 shown in FIG. 11 includes a first transparent electrode 4 on one surface of the laminate 10 of one embodiment of the present invention and the laminate 10'of one embodiment of the present invention. The touch panel member 20'having the conductive member 201 of the above, the second conductive member 202 provided with the second transparent electrode 5 on one surface of the laminate 10 "of one embodiment of the present invention, and organic electroluminescence. In the organic electroluminescence display device 400 having a display unit 40, the laminate 10 and the first conductive member 201, and the first conductive member 201 and the second conductive member 202 each have an adhesive layer 6. The configuration of the touch panel member 20'that is bonded to each other can be the same as the configuration of the touch panel member 20'shown in FIG. 7. Used in the organic electroluminescence display device of one embodiment of the present invention. As the conductive member to be used, the same conductive member as that used for the touch panel member according to the embodiment of the present invention can be used.

[Evaluation methods]
Hereinafter, unless otherwise specified, measurements or evaluations were performed at 25 ° C.
The test piece of the film was cut out from the vicinity of the center of the film.
Unless otherwise specified, the test piece of the film was used for evaluation after adjusting the humidity for 2 hours under the conditions of a temperature of 25 ° C. and a relative humidity of 60%.

<Esterification rate of polyimide precursor resin>
The esterification rate of the polyimide precursor resin was measured by ¹ H NMR measurement for the polyimide precursor resin, and the peak derived from the proton carboxylate present at 11 to 15 ppm and 1.0 to 1.4 ppm and 3.5 to 4. It is calculated from the intensity ratio of the peak derived from the alkyl part of the substituted ester present at 5 ppm. As a calculation formula, when the peak integrated value derived from the carboxylic acid proton of the polyamic acid is "a", the peak integrated value of the terminal alkyl proton of the polyamic acid ester is "b", and the number of alkyl protons is "n". , "Esterification rate (%) = (b / n) / (a + b / n) × 100". For example, when the alkyl portion of the ester is methyl, the "esterification rate" is set when the peak integrated value derived from the carboxylic acid proton of the polyamic acid is "a" and the peak integrated value of the terminal methyl proton of the polyamic acid ester is "b". (%) = (B / 3) / (a + b / 3) × 100 ”.

<Weight average molecular weight of polyimide precursor resin>
The weight average molecular weight of the polyimide precursor resin is such that the polyimide precursor resin is prepared as a N-methylpyrrolidone (NMP) solution having a concentration of 0.5% by weight, and the solution is filtered through a syringe filter (pore size: 0.45 μm). As a developing solvent, a 10 mmol% LiBr-NMP solution having a water content of 500 ppm or less was used, and a GPC device (HLC-8120 manufactured by Tosoh Co., Ltd., column used: GPC LF-804 manufactured by SHODEX) was used, the sample injection amount was 50 μL, and the solvent flow rate was 0. The measurement was performed under the conditions of .5 mL / min and 40 ° C. The weight average molecular weight of the polyimide precursor resin is a polystyrene standard sample having 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) as a reference value for standard polystyrene. The elution time was compared with the calibration curve to determine the weight average molecular weight.

<Weight average molecular weight of polyimide>
Immerse 15 mg of polyimide powder or polyimide film in 15000 mg of N-methylpyrrolidone (NMP), heat to 60 ° C in a water bath, and use a stirrer at a rotation speed of 200 rpm until the dissolution is visually confirmed. Stirring for 3 to 60 hours gave an NMP solution having a concentration of 0.1% by mass. The solution is filtered through a syringe filter (pore size: 0.45 μm), and a 30 mmol% LiBr-NMP solution having 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) is used. Refractometer (RID) detector, column used: SHODEX GPC LF-804 connected in series), sample injection amount 50 μL, solvent flow rate 0.4 mL / min, column temperature 37 ° C, detector temperature 37 ° C The measurement was performed under the conditions of. The weight average molecular weight of the polyimide is a polystyrene standard sample having 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, It was used as a conversion value with respect to standard polystyrene measured based on 070). The elution time was compared with the calibration curve to determine the weight average molecular weight.

<Film thickness measurement method>
A total of 5 film thicknesses at the four corners and the center of the test piece of the polyimide film or laminate cut out to a size of 10 cm x 10 cm were measured using a digital linear gauge (manufactured by Ozaki Seisakusho Co., Ltd., model PDN12 digital gauge). The average of the measured values was taken as the film thickness of the polyimide film or the laminate.

<Total light transmittance>
The total light transmittance was measured by a haze meter (HM150 manufactured by Murakami Color Technology Research Institute) in accordance with JIS K7361-1.

<YI value (yellowness)>
The YI value is based on JIS K7373-2006, using an ultraviolet-visible near-infrared spectrophotometer (JASCO Corporation V-7100), and using an auxiliary illuminant C and a two-degree field of view by the spectrophotometric method. Based on the transmittance measured at intervals of 1 nm in the range of 250 nm or more and 800 nm or less, the tristimulus values X, Y, Z in the XYZ colorimetric system are obtained, and the values of X, Y, Z are obtained from the following equation. Calculated.
YI = 100 (1.2769X-1.592Z) / Y

<Tension modulus>
A test piece of a film cut into a size of 10 mm × 150 mm was measured for a tensile elastic modulus at 25 ° C. in accordance with JIS K7127, with a tensile speed of 50 mm / min and a distance between chucks of 100 mm. A tensile tester (manufactured by Shimadzu Corporation: Autograph AG-X 1N, load cell: SBL-1KN) was used.

<Birerefringence>
The birefringence in the thickness direction at a wavelength of 590 nm was determined as follows.
First, using a phase difference measuring device (for example, manufactured by Oji Measuring Instruments Co., Ltd., product name "KOBRA-WR"), the in-plane retardation value (Re) and thickness of the polyimide film are used with light at 23 ° C. and a wavelength of 590 nm. The directional retardation value (Rth) was measured. For the thickness direction retardation value (Rth), the phase difference value incident at 0 degrees and the phase difference value incident at an angle of 40 degrees were measured, and the thickness direction retardation value Rth was calculated from these phase difference values. The retardation value of the oblique 40-degree incident was measured by injecting light having a wavelength of 590 nm onto the retardation film from a direction inclined by 40 degrees from the normal of the retardation film.
The birefringence in the thickness direction of the polyimide film was obtained by substituting it into the formula: Rth / d (film thickness (nm) of the polyimide film).
The birefringence of the laminate was also determined in the same manner as for the polyimide film.

<Dynamic bending test (φ2.5 mm)>
Hereinafter, the method of the dynamic bending test will be described with reference to FIG.
Two movable metal plates 11 (100 mm × 30 mm) having a movable portion 11a and a non-movable portion 11b are prepared, and the two metal plates 11 are parallel so that the distance between the non-movable portions 11b is 60 mm. Place in. As shown in FIG. 1A, the movable portion 11a of the metal plate 11 is bent so as to be perpendicular to the non-movable portion 11b, and the polyimide film cut out on the movable portion 11a to a size of 20 mm × 100 mm is formed. The test piece 1 is placed, and both ends of the test piece 1 are fixed to the movable portion 11a with Kapton (registered trademark) tape so that the center of the test piece 1 is located at the center of the distance between the metal plates. Next, the movable portion 11a and the non-movable portion 11b are arranged in a straight line so as to be in the state shown in FIG. 1 (B), that is, the test piece 1 curved at the position of half of the long side is placed from both sides. It is sandwiched between the metal plates 11 and the metal plates 11 on both sides are arranged in parallel so that the distance between the metal plates 11 on both sides is 60 mm. In such a state and in a state where the metal plates on both sides are arranged in parallel so that the distance between the metal plates 11 on both sides is 2.5 mm as shown in FIG. 1 (C), the temperature is 25 ° C. and 60%. In a relative humidity (RH) environment, the bending is repeated 90 times per minute. As the test jig, a constant temperature and humidity constant humidity test system (manufactured by Yuasa System Equipment Co., Ltd., surface-shaped no-load U-shaped expansion and contraction test jig DMX-FS) can be used.
The number of bends (number of breaks) before breaking was measured.

<Pencil hardness>
The pencil hardness of the polyimide film is determined by adjusting the humidity of the measurement sample for 2 hours under the 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 ( The pencil hardness test (0.98 N load) specified in 1999) was performed on the surface of the film to evaluate the highest pencil hardness that does not damage the film. As a testing machine, a pencil scratch coating film hardness testing machine manufactured by Toyo Seiki Co., Ltd. was used.
The pencil hardness of the laminate was measured in the same manner as in the method for measuring the pencil hardness of the polyimide film except that the load was 9.8 N.

(Example 1)
<Synthesis of tetracarboxylic dianhydride represented by formula (a-1)>
With reference to Synthesis Example 1 of WO2014 / 046180, a tetracarboxylic dianhydride (TMPBPTME) represented by the following formula (a-1) was synthesized.

<Synthesis of polyimide precursor resin>
A 500 mL separable flask was replaced with nitrogen to dissolve 396.14 g of dehydrated dimethylacetamide (DMAc) and 29.66 g (92.7 mmol) of 2,2'-bis (trifluoromethyl) benzidine (TFMB). When the solution was controlled to have a liquid temperature of 30 ° C, 56.98 g (92.1 mmol) of TMPBPTME was gradually added so that the temperature rise was 2 ° C or less, and the mixture was stirred with a mechanical stirrer for 3 hours to obtain polyamic acid. A solution was obtained. Then, 22.04 g (185 mmol) of N, N-dimethylformamide dimethylacetal (manufactured by Tokyo Kasei) was added to the polyamic acid solution, and the mixture was further stirred for 3 hours to obtain a polyamic acid ester solution. 216.40 g of water was gradually added to the obtained polyamic acid ester solution to obtain a solution in which slight turbidity was observed. 649.19 g of water was added to the turbid solution at once to obtain a white slurry. The slurry was filtered, washed with water 5 times, and then dried in an oven heated to 100 ° C. under reduced pressure for 10 hours to obtain 61.9 g of a powder of the polyimide precursor resin 1.
In the polyimide precursor resin 1, 99.9% of all carboxy groups were methyl esterified.

<Manufacturing of polyimide film>
N, N-dimethylacetamide (DMAc) was added to the polyimide precursor resin 1 to prepare a polyimide precursor resin composition 1 having a solid content of 12%.
Using the polyimide precursor resin composition 1 having a solid content of 12%, the following steps (1) and (2) were carried out to produce a single-layer polyimide film having a thickness of 40 μm.
(1) The polyimide precursor resin composition is applied onto a glass plate, dried in a circulation oven at 120 ° C. for 10 minutes, cooled to 25 ° C. to form a polyimide precursor resin coating film, and the polyimide precursor resin is formed. The coating film was peeled off.
(2) The peeled polyimide precursor resin coating film was cut out to a size of 150 mm × 200 mm. Using two metal frames (outer dimensions 150 mm x 200 mm, inner dimensions 130 mm x 180 mm), the cut out polyamic acid ester resin coating film is sandwiched, and the metal frame and the polyamic acid ester resin coating film are fixed with a fixing jig. did. The fixed polyimide precursor resin coating film was heated to 300 ° C. at a heating rate of 10 ° C./min in a circulation oven under a nitrogen stream (oxygen concentration 100 ppm or less), held at 300 ° C. for 1 hour, and then 25 ° C. It was cooled to the above to produce a single-layer polyimide film.
Table 1 shows the evaluation results of the obtained polyimide film.

(Example 2)
In Example 1, instead of adding 22.04 g (185 mmol) of N, N-dimethylformamide dimethylacetal (manufactured by Tokyo Kasei) when producing the polyimide precursor resin, N, N-dimethylformamide dimethylacetal (Tokyo). The polyimide precursor resin 2 was produced in the same manner as in Example 1 except that the amount was 20.94 g (176 mmol). In the polyimide precursor resin 2, 95.0% of all carboxy groups were methyl esterified.
Using the obtained polyimide precursor resin 2, a polyimide film was produced in the same manner as in Example 1.
Table 1 shows the evaluation results of the obtained polyimide film.

(Example 3)
In Example 1, when producing the polyimide precursor resin, instead of adding 22.04 g (185 mmol) of N, N-dimethylformamide dimethylacetal (manufactured by Tokyo Kasei), N, N-dimethylformamide diethylacetal (Tokyo). The polyimide precursor resin 3 was produced in the same manner as in Example 1 except that the amount was 25.90 g (176 mmol). In the polyimide precursor resin 3, 95.1% of all carboxy groups were methyl esterified.
Using the obtained polyimide precursor resin 3, a polyimide film was produced in the same manner as in Example 1.
Table 1 shows the evaluation results of the obtained polyimide film.

(Example 4)
In Example 1, N, N-dimethylformamide din-propyl instead of adding 22.04 g (185 mmol) of N, N-dimethylformamide dimethylacetal (manufactured by Tokyo Kasei) when producing the polyimide precursor resin. The polyimide precursor resin 4 was produced in the same manner as in Example 1 except that acetal (manufactured by Tokyo Kasei Co., Ltd.) weighed 30.79 g (176 mmol). In the polyimide precursor resin 4, 95.0% of all carboxy groups were methyl esterified.
Using the obtained polyimide precursor resin 4, a polyimide film was produced in the same manner as in Example 1.
Table 1 shows the evaluation results of the obtained polyimide film.

(Example 5)
A 500 mL separable flask was replaced with nitrogen to dissolve 402.41 g of dehydrated dimethylacetamide (DMAc) and 30.13 g (94.1 mmol) of 2,2'-bis (trifluoromethyl) benzidine (TFMB). When the temperature of the solution was controlled to be 30 ° C, 57.91 g (93.6 mmol) of TMPBPTME was gradually added so that the temperature rise was 2 ° C or less, and the mixture was stirred with a mechanical stirrer for 3 hours to obtain polyamic acid. A solution was obtained. Then, 22.4 g (189 mmol) of N, N-dimethylformamide dimethylacetal (manufactured by Tokyo Kasei) was added to the polyamic acid solution, and the mixture was further stirred for 3 hours to obtain a polyamic acid ester solution. 220.23 g of water was gradually added to the obtained polyamic acid ester solution to obtain a solution in which slight turbidity was observed. 668.81 g of water was added to the turbid solution at once to obtain a white slurry. The slurry was filtered, washed with water 5 times, and then dried in an oven heated to 100 ° C. under reduced pressure for 10 hours to obtain 65.2 g of a powder of the polyimide precursor resin 5.
In the polyimide precursor resin 5, 95.1% of all carboxy groups were methyl esterified.
Using the obtained polyimide precursor resin 5, a polyimide film was produced in the same manner as in Example 1.
Table 1 shows the evaluation results of the obtained polyimide film.

(Example 6)
A 500 mL separable flask was replaced with nitrogen to dissolve 388.37 g of dehydrated dimethylacetamide (DMAc) and 29.08 g (90.8 mmol) of 2,2'-bis (trifluoromethyl) benzidine (TFMB). When the solution was controlled to have a liquid temperature of 30 ° C., 55.27 g (89.3 mmol) of TMPBPTME was gradually added so that the temperature rise was 2 ° C. or less, and the mixture was stirred with a mechanical stirrer for 3 hours to obtain polyamic acid. A solution was obtained. Then, 20.36 g (171 mmol) of N, N-dimethylformamide dimethylacetal (manufactured by Tokyo Kasei) was added to the polyamic acid solution, and the mixture was further stirred for 3 hours to obtain a polyamic acid ester solution. 211.40 g of water was gradually added to the obtained polyamic acid ester solution to obtain a solution in which slight turbidity was observed. 635.2 g of water was added to the turbid solution at once to obtain a white slurry. The slurry was filtered, washed with water 5 times, and then dried in an oven heated to 100 ° C. under reduced pressure for 10 hours to obtain 57.6 g of a powder of the polyimide precursor resin 6.
In the polyimide precursor resin 6, 95.2% of all carboxy groups were methyl esterified.
Using the obtained polyimide precursor resin 6, a polyimide film was produced in the same manner as in Example 1.
Table 1 shows the evaluation results of the obtained polyimide film.

(Comparative Example 1)
In Example 1, instead of adding 22.04 g (185 mmol) of N, N-dimethylformamide dimethylacetal (manufactured by Tokyo Kasei) when producing the polyimide precursor resin, N, N-dimethylformamide dimethylacetal (Tokyo). A comparative polyimide precursor resin 1 was produced in the same manner as in Example 1 except that the amount was 20.71 g (173 mmol). In the comparative polyimide precursor resin 1, 94.0% of all carboxy groups were methyl esterified.
Using the obtained comparative polyimide precursor resin 1, a polyimide film C1 was produced in the same manner as in Example 1.
Table 1 shows the evaluation results of the obtained polyimide film.

(Comparative Example 2)
<Synthesis of polyamic acid>
A 500 mL separable flask was substituted with nitrogen to dissolve 396.14 g of dehydrated dimethylacetamide (DMAc) and 29.66 g (92.7 mmol) of 2,2'-bis (trifluoromethyl) benzidine (TFMB). When the solution was controlled to have a liquid temperature of 30 ° C., 56.98 g (92.1 mmol) of TMPBPTME was gradually added so that the temperature rise was 2 ° C. or lower, and the mixture was stirred with a mechanical stirrer for 3 hours. , A polyamic acid solution was obtained.

<Manufacturing of polyimide film>
By adding N, N-dimethylacetamide (DMAc) to the polyamic acid solution, a comparative polyimide precursor resin composition C2 having a solid content of 12% was prepared.
In the production of the polyimide film of Example 1, the polyimide film of Comparative Example 2 was used in the same manner as in Example 1 except that the comparative polyimide precursor resin composition C2 was used instead of the polyimide precursor resin composition 1. I got C2.
Table 1 shows the evaluation results of the obtained polyimide film.

(Comparative Example 3)
<Synthesis of polyimide>
A 500 mL separable flask was substituted with nitrogen to dissolve 396.14 g of dehydrated dimethylacetamide (DMAc) and 29.66 g (92.7 mmol) of 2,2'-bis (trifluoromethyl) benzidine (TFMB). When the temperature of the solution was controlled to be 30 ° C, 56.98 g (92.1 mmol) of TMPBPTME was gradually added so that the temperature rise was 2 ° C or less, and the mixture was stirred with a mechanical stirrer for 3 hours. A polyamic acid solution was obtained. Next, 1.69 g (16.6 mmol) of pyridine and 32.20 g (412.8 mmol) of acetic anhydride as catalysts were added, and the mixture was further stirred for 3 hours to obtain a polyimide solution. Then, 216.40 g of 2-propyl alcohol (IPA) was gradually added to the solution cooled to room temperature to obtain a solution in which slight turbidity was observed. IPA324.59 g was added to the turbid solution at once to obtain a white slurry. The slurry was filtered and washed with IPA 5 times, and then dried in an oven heated to 100 ° C. under reduced pressure for 6 hours to obtain 60.4 g of polyimide C3 powder.

<Manufacturing of polyimide film>
DMAc was added to the polyimide C3 so that the solid content concentration of the polyimide C3 was 19% by mass to prepare a polyimide varnish C3 in which the polyimide C3 was 19% by mass in the varnish.
By performing the following procedures (i) to (ii) using the polyimide varnish C3, a single-layer polyimide film C3 having a thickness of 40 μm was produced.
(I) Polyimide varnish C3 was applied onto a glass plate, dried in a circulation oven at 120 ° C. for 10 minutes, cooled to 25 ° C., and the polyimide resin coating film was peeled off.
(Ii) The peeled polyimide resin coating film was cut out to a size of 150 mm × 200 mm. Two metal frames (outer dimensions 150 mm × 200 mm, inner dimensions 130 mm × 180 mm) were used to sandwich the cut out polyimide resin coating film, and the metal frame and the polyimide resin coating film were fixed with a fixing jig. The fixed polyimide resin coating film is heated to 300 ° C. at a heating rate of 10 ° C./min in a circulation oven under a nitrogen stream (oxygen concentration 100 ppm or less), held at 300 ° C. for 1 hour, and then cooled to 25 ° C. Then, a single-layer polyimide film C3 was produced.
Table 1 shows the evaluation results of the obtained polyimide film.

[Summary of Table 1]
The polyimide film of Comparative Example 2 produced by thermally imidizing using polyamic acid, which is a conventional polyimide precursor, has a low molecular weight of polyimide after film production, has poor bending resistance, and has high transparency. It has dropped.
The polyimide film of Comparative Example 1 produced by thermal imidization using the comparative polyimide precursor resin 1 having a low esterification rate also has a decrease in the molecular weight of the polyimide after the film is produced, which deteriorates bending resistance and transparency. It has dropped.
The polyimide film of Comparative Example 3 corresponding to Patent Document 2 had a high elastic modulus and good bending resistance, but had a high phase difference and a large birefringence.
On the other hand, the polyimide films of Examples 1 and 2 produced by thermal imidization using the esterified polyimide precursor resin of the present invention have bending resistance without reducing the molecular weight of the polyimide after film production. The polyimide film was good, had good transparency without deterioration, had a high elastic modulus, and had a phase difference even lower than that of Comparative Examples 1 and 2.

(Example 7)
<Synthesis of polyimide precursor resin>
A 500 mL separable flask was replaced with nitrogen to dissolve 392.37 g of dehydrated dimethylacetamide (DMAc) and 36.08 g (112.7 mmol) of 2,2'-bis (trifluoromethyl) benzidine (TFMB). When the temperature of the solution was controlled to be 30 ° C, 49.19 g (110.7 mmol) of 4,4'-(hexafluoroisopropylidene) diphthalic acid anhydride (6FDA) was added, and the temperature rise became 2 ° C or less. The mixture was gradually added and stirred with a mechanical stirrer for 3 hours to obtain a polyamic acid solution. Then, 24.99 g (209.7 mmol) of N, N-dimethylformamide dimethylacetal (manufactured by Tokyo Kasei) was added to the polyamic acid solution, and the mixture was further stirred for 3 hours to obtain a polyamic acid ester solution. 226.55 g of water was gradually added to the obtained polyamic acid ester solution to obtain a solution in which slight turbidity was observed. 453.1 g of water was added to the turbid solution at once to obtain a white slurry. The slurry was filtered, washed with water 5 times, and then dried in an oven heated to 100 ° C. under reduced pressure for 10 hours to obtain 62.9 g of a powder of the polyimide precursor resin 7.
In the polyimide precursor resin 7, 95.1% of all carboxy groups were methyl esterified.
Using the obtained polyimide precursor resin 7, a polyimide film was produced in the same manner as in Example 1.
Table 2 shows the evaluation results of the obtained polyimide film.

(Comparative Example 4)
<Synthesis of polyamic acid>
A 500 mL separable flask was replaced with nitrogen to dissolve 402.4 g of dehydrated dimethylacetamide (DMAc) and 37.0 g (115.5 mmol) of 2,2'-bis (trifluoromethyl) benzidine (TFMB). When the temperature of the solution was controlled to be 30 ° C, 50.92 g (114.6 mmol) of 6FDA was gradually added so that the temperature rise was 2 ° C or less, and the mixture was stirred with a mechanical stirrer for 3 hours to prepare the polyamic acid solution. Obtained.

<Manufacturing of polyimide film>
By adding N, N-dimethylacetamide (DMAc) to the polyamic acid solution, a comparative polyimide precursor resin composition C4 having a solid content of 12% was prepared.
In the production of the polyimide film of Example 1, the polyimide film of Comparative Example 4 was used in the same manner as in Example 1 except that the comparative polyimide precursor resin composition C4 was used instead of the polyimide precursor resin composition 1. Obtained C4.
Table 2 shows the evaluation results of the obtained polyimide film.

(Comparative Example 5)
<Synthesis of polyimide>
A 500 mL separable flask was substituted with nitrogen to dissolve 398.58 g of dehydrated dimethylacetamide (DMAc) and 36.65 g (114.4 mmol) of 2,2'-bis (trifluoromethyl) benzidine (TFMB). When the temperature of the solution was controlled to be 30 ° C, 50.54 g (113.8 mmol) of 6FDA was gradually added so that the temperature rise was 2 ° C or less, and the mixture was stirred with a mechanical stirrer for 3 hours. A polyamic acid solution was obtained. Next, 1.73 g (79.1 mmol) of pyridine and 55.85 g (547.1 mmol) of acetic anhydride as catalysts were added, and the mixture was further stirred for 3 hours to obtain a polyimide solution. Then, 233.65 g of 2-propyl alcohol (IPA) was gradually added to the solution cooled to room temperature to obtain a solution in which slight turbidity was observed. IPA467.5 g was added to the turbid solution at once to obtain a white slurry. The slurry was filtered and washed with IPA 5 times, and then dried in an oven heated to 100 ° C. under reduced pressure for 6 hours to obtain 66.1 g of polyimide C5 powder.

<Manufacturing of polyimide film>
In Comparative Example 3, a single-layer polyimide film C5 was produced in the same manner as in Comparative Example 3 except that the polyimide C5 was used instead of the polyimide C3.
Table 2 shows the evaluation results of the obtained polyimide film.

(Example 8)
<Synthesis of polyimide precursor resin>
A 500 mL separable flask was replaced with nitrogen to dissolve 385.52 g of dehydrated dimethylacetamide (DMAc) and 50.34 g (157.2 mmol) of 2,2'-bis (trifluoromethyl) benzidine (TFMB). When the temperature of the solution was controlled to be 30 ° C, 24.15 g (110.7 mmol) of pyromellitic dianhydride (PMDA) was gradually added so that the temperature rise was 2 ° C or less, and a mechanical stirrer was added. Was stirred for 3 hours to obtain a polyamic acid solution. Then, 53.53 g (449.2 mmol) of N, N-dimethylformamide dimethylacetal (manufactured by Tokyo Kasei) was added to the polyamic acid solution, and the mixture was further stirred for 3 hours to obtain a polyamic acid ester solution. 223.3 g of water was gradually added to the obtained polyamic acid ester solution to obtain a solution in which slight turbidity was observed. 446.2 g of water was added to the turbid solution at once to obtain a white slurry. The slurry was filtered, washed with water 5 times, and then dried in an oven heated to 100 ° C. under reduced pressure for 10 hours to obtain 66.7 g of a powder of the polyimide precursor resin 8.
In the polyimide precursor resin 8, 95.0% of all carboxy groups were methyl esterified.
Using the obtained polyimide precursor resin 8, a polyimide film was produced in the same manner as in Example 1.
Table 2 shows the evaluation results of the obtained polyimide film.

(Comparative Example 6)
<Synthesis of polyamic acid>
A 500 mL separable flask was replaced with nitrogen to dissolve 398.19 g of dehydrated dimethylacetamide (DMAc) and 51.99 g (162.4 mmol) of 2,2'-bis (trifluoromethyl) benzidine (TFMB). When the temperature of the solution was controlled to be 30 ° C, 35.13 g (161.1 mmol) of PMDA was gradually added so that the temperature rise was 2 ° C or less, and the mixture was stirred with a mechanical stirrer for 3 hours to prepare a polyamic acid solution. Got

<Manufacturing of polyimide film>
By adding N, N-dimethylacetamide (DMAc) to the polyamic acid solution, a comparative polyimide precursor resin composition C6 having a solid content of 12% was prepared.
In the production of the polyimide film of Example 1, the polyimide film of Comparative Example 6 was used in the same manner as in Example 1 except that the comparative polyimide precursor resin composition C6 was used instead of the polyimide precursor resin composition 1. I got C6.
Table 2 shows the evaluation results of the obtained polyimide film.

(Comparative Example 7)
<Synthesis of polyimide>
A 500 mL separable flask was substituted with nitrogen to dissolve 405.60 g of dehydrated dimethylacetamide (DMAc) and 52.96 g (165.4 mmol) of 2,2'-bis (trifluoromethyl) benzidine (TFMB). When the temperature of the solution was controlled to be 30 ° C, 35.82 g (164.2 mmol) of PMDA was gradually added so that the temperature rise was 2 ° C or less, and the mixture was stirred with a mechanical stirrer for 3 hours. A polyamic acid solution was obtained. Next, 2.598 g (32.8 mmol) of pyridine and 83.83 g (821.1 mmol) of acetic anhydride as catalysts were added, and the mixture was further stirred for 3 hours to obtain a polyimide solution. Then, 247.3 g of 2-propyl alcohol (IPA) was gradually added to the solution cooled to room temperature to obtain a solution in which slight turbidity was observed. IPA494.6 g was added to the turbid solution at once to obtain a white slurry. The slurry was filtered and washed with IPA 5 times, and then dried in an oven heated to 100 ° C. under reduced pressure for 6 hours to obtain 69.9 g of polyimide C7 powder.

<Manufacturing of polyimide film>
In Comparative Example 3, a single-layer polyimide film C7 was produced in the same manner as in Comparative Example 3 except that the polyimide C7 was used instead of the polyimide C3.
Table 2 shows the evaluation results of the obtained polyimide film.

(Examples 9 to 14, Comparative Examples 8 to 10: Production of laminated body)
A resin composition for a hard coat layer having the following composition was prepared.
(Resin composition for hard coat layer)
・ 40% by mass methyl isobutyl ketone solution of pentaerythritol triacrylate: 65 parts by mass of solid content ・ Silica fine particles (MIBK-SD-L manufactured by Nissan Chemical Co., Ltd., methyl isobutyl ketone dispersed silica sol, SiO ² 30% by mass): 30% by mass of solid content Part 1-Hydroxy-cyclohexyl-phenyl-ketone (BASF, Irgacure 184) 5 parts by mass solid content The resin composition for the hard coat layer is placed on each of the polyimide films of Examples 1 to 6 and Comparative Examples 1 to 3. It was applied and cured by irradiating it with ultraviolet rays at an exposure amount of 200 mJ / cm ² under a nitrogen stream to form a cured film (hard coat layer) having a film thickness of about 10 μm, and a laminate was produced.
Table 3 shows the evaluation results of the obtained laminate.

(Examples 15 to 16: Production of laminated body)
Polyimide films were produced in the same manner as in Examples 7 and 8. Then, the same resin composition for a hard coat layer as in Example 9 is applied onto each of the obtained polyimide films to form a coating film for forming a hard coat layer, and ultraviolet rays are applied to the coating film for forming the hard coat layer. It was cured by irradiating it with an exposure amount of 200 mJ / cm ² under an air stream to form a cured film (hardcoat layer) having a film thickness of about 10 μm, and a laminate was produced.
Table 4 shows the evaluation results of the obtained laminate.

Claims (13)

The following general formula (1-1) or the following general formula (1-2)

(In the general formulas (1-1) and (1-2), A is a tetravalent residue of at least one tetracarboxylic acid dianhydride selected from the group consisting of the following groups A1 and the following groups A2. B represents a divalent group which is a residue of at least one diamine selected from the group consisting of the following group B1 and the following group B2, and R represents a hydrogen atom or an alkyl having 1 to 10 carbon atoms. It has a structural unit represented by () and is represented by a group.
<Group A1: 4,4'-(hexafluoroisopropyridene) diphthalic acid dianhydride, 4,4'-oxydiphthalic acid dianhydride, cyclobutanetetracarboxylic acid dianhydride, and the following chemical formula (a-1). Acid dianhydride>

<Group A2: pyromellitic acid dianhydride, 3,3', 4,4'-biphenyltetracarboxylic dianhydride, and p-phenylenebis (trimeritate anhydride)>
<Group B1: 2,2'-bis (trifluoromethyl) benzidine, 4,4'-diaminodiphenyl ether, bis (4-aminophenyl) sulfone, and bis [4- (4-aminophenoxy) phenyl] sulfone>
<Group B2: Phenylene diamine, 4-aminophenyl 4-aminobenzoic acid, bis (4-aminophenyl) terephthalate, 4,4'-diaminobenzanilide, and N, N'-bis (4-aminophenyl) terephthalamide. ＞
In the general formulas (1-1) and (1-2), it consists of A which is a residue of at least one tetracarboxylic dianhydride selected from the group consisting of the group A1 and the group B1. Containing at least one of B, which is a residue of at least one diamine selected from the group,
95.0% or more of all R contained in the general formulas (1-1) and (1-2) are alkyl groups having 1 to 10 carbon atoms.
Furthermore, the following general formula (2)

{In the general formula (2), X is the following formulas (x1) to (x4).

(In equation (x3), L is -O-, -S-, -CH _2- , -CH (CH ₃ )-, -C (CH ₃ ) _2- , -C (CF ₃ ) _2- , or. -CO-, * represents at least one divalent group selected from the group consisting of the structures represented by), and B represents the group consisting of the group B1 and the group B2. Represents a divalent group that is a residue of at least one diamine to be made. } May have a structural unit represented by
A polyimide precursor resin having a weight average molecular weight of 108,000 or more in terms of polystyrene in gel permeation chromatography. In the general formulas (1-1) and (1-2), A is 4,4'-(hexafluoroisopropyridene) diphthalic acid anhydride, cyclobutanetetracarboxylic acid dianhydride, and the chemical formula (a-1). The polyimide precursor resin according to claim 1, which represents a tetravalent group which is a residue of at least one tetracarboxylic acid anhydride selected from the group consisting of. The second aspect of claim 1 or 2, wherein in the general formulas (1-1) and (1-2), B represents a divalent group which is a residue of 2,2'-bis (trifluoromethyl) benzidine. Polyimide precursor resin. A step of preparing a polyimide precursor resin composition containing the polyimide precursor resin according to any one of claims 1 to 3 and an organic solvent.
A step of applying the polyimide precursor resin composition to a support to form a polyimide precursor resin coating film, and a step of forming the polyimide precursor resin coating film.
A method for producing a polyimide film, comprising a step of imidizing the polyimide precursor resin by heating the polyimide precursor resin coating film. A step of manufacturing a polyimide film by the method for manufacturing a polyimide film according to claim 4;
A step of applying a composition for a hard coat layer containing at least one of a radically polymerizable compound and a cationically polymerizable compound to at least one surface of the polyimide film to form a coating film for forming a hard coat layer.
A method for producing a laminate, comprising a step of forming a hard coat layer containing at least one polymer of a radically polymerizable compound and a cationically polymerizable compound by curing the coating film for forming a hard coat layer. The following general formula (1')

(In the general formula (1'), A represents a tetravalent group which is a residue of at least one tetracarboxylic acid dianhydride selected from the group consisting of the following groups A1 and the following groups A2, and B is. It has a structural unit represented by a divalent group which is a residue of at least one diamine selected from the group consisting of the following group B1 and the following group B2).
<Group A1: 4,4'-(hexafluoroisopropyridene) diphthalic acid dianhydride, 4,4'-oxydiphthalic acid dianhydride, cyclobutanetetracarboxylic acid dianhydride, and the following chemical formula (a-1). Acid dianhydride>

<Group A2: pyromellitic dianhydride, 3,3', 4,4'-biphenyltetracarboxylic dianhydride, and p-phenylenebis (trimeritate anhydride)>
<Group B1: 2,2'-bis (trifluoromethyl) benzidine, 4,4'-diaminodiphenyl ether, bis (4-aminophenyl) sulfone, and bis [4- (4-aminophenoxy) phenyl] sulfone>
<Group B2: Phenylene diamine, 4-aminophenyl 4-aminobenzoic acid, bis (4-aminophenyl) terephthalate, 4,4'-diaminobenzanilide, and N, N'-bis (4-aminophenyl) terephthalamide. ＞
In the general formula (1'), A contains at least a tetravalent group which is a residue of the acid dianhydride represented by the chemical formula (a-1).
Furthermore, the following general formula (2)

{In the general formula (2), X is the following formulas (x1) to (x4).

(In equation (x3), L is -O-, -S-, -CH _2- , -CH (CH ₃ )-, -C (CH ₃ ) _2- , -C (CF ₃ ) _2- , or. -CO-, * represents at least one divalent group selected from the group consisting of the structures represented by), and B represents the group consisting of the group B1 and the group B2. Represents a divalent group that is a residue of at least one diamine to be made. Contains a polyimide resin that may have a structural unit represented by }.
The total light transmittance measured according to JIS K7361-1 is 85.0% or more in terms of the film thickness of 40 μm, and the yellowness calculated according to JIS K7373-2006 is the film thickness (μm). The value divided by is less than 0.15,
The birefringence in the thickness direction at a wavelength of 590 nm is less than 0.025.
A test piece of 10 mm × 150 mm has a tensile elastic modulus of 4.0 GPa or more in a tensile test measured at 25 ° C., with a tensile speed of 50 mm / min and a distance between chucks of 100 mm, in accordance with JIS K7127, and is as follows. A polyimide film having a bending count of 100,000 or more in a dynamic bending test.
(Dynamic bending test)
A 20 mm × 100 mm test piece is curved at the half position of the long side, sandwiched between metal plates arranged in parallel, and 25 ° C., 60% so that the distance between the metal plates on both sides is 60 mm to 2.5 mm. In a relative humidity (RH) environment, the test piece is repeatedly bent 90 times per minute. In the general formula (1), A consists of a group consisting of 4,4'-(hexafluoroisopropyridene) diphthalic acid anhydride, cyclobutanetetracarboxylic acid dianhydride, and the chemical formula (a-1). The polyimide film according to claim 6, which represents a tetravalent group which is a residue of at least one tetracarboxylic acid anhydride selected. The polyimide film according to claim 6 or 7, wherein in the general formula (1), B represents a divalent group which is a residue of 2,2'-bis (trifluoromethyl) benzidine. A laminate having the polyimide film according to any one of claims 6 to 8 and a hard coat layer containing at least one polymer of a radically polymerizable compound and a cationically polymerizable compound. A display member which is the polyimide film according to any one of claims 6 to 8 or the laminate according to claim 9. The polyimide film according to any one of claims 6 to 8 or the laminate according to claim 9 and the laminate.
A transparent electrode composed of a plurality of conductive portions arranged on one surface side of the polyimide film or the laminate,
A touch panel member having a plurality of take-out wires electrically connected on at least one side of the end of the conductive portion. The polyimide film according to any one of claims 6 to 8 or the laminate according to claim 9 and the laminate.
A liquid crystal display device having a liquid crystal display unit having a liquid crystal layer between facing substrates, which is arranged on one surface side of the polyimide film or the laminated body. The polyimide film according to any one of claims 6 to 8 or the laminate according to claim 9 and the laminate.
An organic electroluminescence display device having an organic electroluminescence display unit having an organic electroluminescence layer between facing substrates arranged on one surface side of the polyimide film or the laminate.

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