JP6862956B2 - Transparent polyimide film for flexible display front plate and its manufacturing method, and organic electroluminescence display - Google Patents

Description

The present invention relates to a transparent polyimide film for a flexible display front plate, a method for manufacturing the same, and an organic electroluminescence display. More specifically, the present invention is a transparent polyimide film for a flexible display front plate that suppresses image distortion and has excellent scratch resistance. And its manufacturing method, and an organic polyimide display.

Conventionally, glass has been used as a front plate of an organic electroluminescence display (organic EL display), but with the recent increase in flexibility, an alternative technology (material) is desired.

The front plate of a flexible display represented by a flexible smartphone is required to have transparency, bending resistance, and hardness (scratch resistance), and as a technology to achieve this, a technology of adding a large amount of silica particles to transparent polyimide is attracting attention. (See, for example, Patent Documents 1 and 2).

However, when a flexible smartphone is actually manufactured using a front plate using this technology, there is a problem that the image is distorted when the screen is viewed from an angle.
In general, there is often a problem with the flatness of the front member as a cause of distortion of the image on the display, so the film was re-formed so that the surface roughness (Ra) became small, and the evaluation was performed again. Distortion did not improve.

U.S. Pat. No. 8,207,256 Japanese Unexamined Patent Publication No. 2016-9392

The present invention has been made in view of the above problems and situations, and the problems to be solved are a transparent polyimide film for a flexible display front plate which suppresses image distortion and has excellent scratch resistance, a method for producing the same, and an organic material. It is to provide an electroluminescence display.

In order to solve the above problems, the present inventor evaluated the projected image of the transparent polyimide film in the process of examining the cause of the above problems, and found that the standard deviation σ of the gray value at the 8-bit gray scale was within a specific range. In addition, by adjusting the occupied area ratio of the black part in the binarized image to a specific value or less, the transparent polyimide film for the flexible display front plate, which suppresses image distortion and has excellent scratch resistance, and its manufacturing method. , And also found that it is possible to provide an organic polyimide display, and came to the present invention.

That is, the above-mentioned problem according to the present invention is solved by the following means.

1. 1. A transparent polyimide film for a flexible display front plate containing metal oxide particles, a silane coupling agent, and polyimide.
The polyimide is one of a polyimide obtained by polymerizing the following acid anhydride B and the following diamine B, and a polyimide obtained by polymerizing the following acid anhydride C, the following diamine C and the following diamine D.
The metal oxide particles have an average primary particle size in the range of 10 to 100 nm, and the content is 20 to 70% by mass with respect to the total solid content (100% by mass) in the transparent polyimide film. Within range,
When the projected image of the transparent polyimide film is analyzed, the standard deviation σ of the gray value in the 8-bit gray scale is within the range of 0.50 to 1.10, and the occupied area ratio of the black part in the binarized image is 50% or less. A transparent polyimide film for the front plate of a flexible display, which is characterized by being adjusted to.

2 . The transparent polyimide film for a flexible display front plate according to item 1, wherein the metal oxide particles are silica particles.

3 . The transparent polyimide film for a flexible display front plate according to item (1) or (2) , which further contains an aromatic compound.
4 . The aromatic compound is any one of the following aromatic compounds A, the following aromatic compounds B, and the following aromatic compounds C (where n in the formula is 1). The transparent polyimide film for the front plate of a flexible display according to the third item.

5 . Any one of items 1 to 4, wherein the silane coupling agent has at least one group selected from an acrylic group, a methacryl group, an isocyanurate group, a phenyl group and a fluoro group. The transparent polyimide film for the flexible display front plate described in.

6 . A method for producing a transparent polyimide film for a flexible display front plate, which contains metal oxide particles, a silane coupling agent, and polyimide.
A step of preparing a dope containing the metal oxide particles, the silane coupling agent, the polyimide, and a solvent.
The step of casting the dope on the support to form a web, and
Have,
The polyimide is one of a polyimide obtained by polymerizing the following acid anhydride B and the following diamine B, and a polyimide obtained by polymerizing the following acid anhydride C, the following diamine C and the following diamine D.
The metal oxide particles have an average primary particle size in the range of 10 to 100 nm, and the content is 20 to 70% by mass with respect to the total solid content (100% by mass) in the transparent polyimide film. Within range,
When the projected image of the transparent polyimide film is evaluated, the standard deviation σ of the gray value in the 8-bit gray scale is within the range of 0.50 to 1.10, and the occupied area ratio of the black portion in the binarized image is 50% or less. A method for producing a transparent polyimide film for a flexible display front plate, which is characterized by adjusting to.

7 . The method for producing a transparent polyimide film for a flexible display front plate according to Item 6 , wherein the dope further contains an azeotropic dehydrating agent in the step of preparing the dope.

8 . An organic electroluminescence display comprising the transparent polyimide film according to any one of items 1 to 5.

According to the above means of the present invention, it is possible to provide a transparent polyimide film for a flexible display front plate which suppresses image distortion and has excellent scratch resistance, a method for producing the same, and an organic electroluminescence display.

Although the mechanism of expression and the mechanism of action of the effects of the present invention have not been clarified, it is inferred as follows.

As described above, when a transparent polyimide film obtained by adding a large amount of silica particles to transparent polyimide is used as the front plate of a flexible display, there is a problem that the image is distorted when the screen is viewed from an angle, which is caused by surface roughness ( It was not improved even if the film was re-formed so that Ra) became smaller.
Therefore, when this polyimide film was observed through a point light source, unevenness was observed in the projected image.
This is because water is generated by the reaction when metal oxide particles such as silica particles are introduced into the polyimide, and due to this, the morphology in the film is partially changed during film formation, and when viewed with a point light source. It is presumed that it was observed as unevenness of the projected image, that is, distortion of the image on the display.

Therefore, in the present invention, when the projected image of the transparent polyimide film is evaluated, the standard deviation σ of the gray value at the 8-bit gray scale is within the range of 0.50 to 1.10, and the black portion in the binarized image. By adopting a transparent polyimide film whose occupied area ratio is adjusted to 50% or less as the front plate, it is considered that unevenness of the projected image when viewed with a point light source, that is, distortion of the display image can be suppressed. ing.

Further, since the transparent polyimide film contains metal oxide particles having an average primary particle size of 10 to 100 nm in the range of 20 to 70% by mass, the scratch resistance of the film can be improved. thinking.

Schematic diagram showing the analysis method of the projected image of the transparent polyimide film of the present invention.

The transparent polyimide film for the flexible display front plate of the present invention contains a metal oxide particle, a silane coupling agent, and a polyimide, and the polyimide is obtained by polymerizing the acid anhydride B and the diamine B. Further, it is any of the polyimides obtained by polymerizing the acid anhydride C, the diamine C and the diamine D , and the metal oxide particles have an average primary particle size in the range of 10 to 100 nm. , The content is in the range of 20 to 70% by mass with respect to the total solid content (100% by mass) in the transparent polyimide film, and when the projected image of the transparent polyimide film is evaluated, the standard of gray value in 8 bit gray scale. The deviation σ is within the range of 0.50 to 1.10, and the occupied area ratio of the black portion in the binarized image is adjusted to 50% or less. This feature is a technical feature common to or corresponding to the following embodiments .

In an embodiment of the present invention, it is preferable that the metal oxide particles are silica particles. Since the refractive indexes of transparent polyimide and silica are close to each other, scattering is less likely to occur, and higher transparency can be achieved.

Further, from the viewpoint of effectively removing water generated by dehydration condensation, it is preferable that an aromatic compound is further contained, and the aromatic compound is the following aromatic compound A and the following aromatic compound B. , And any of the following aromatic compounds C is more preferable.

On the other hand, from the viewpoint of reducing the influence of polyimide film formation by sufficiently slowing the reaction rate of dehydration condensation, it is possible to use a silane coupling agent that does not contain a catalytic group such as an amino group. preferable. Further, considering compatibility with polyimide, it is preferable that the silane coupling agent has at least one group selected from an acrylic group, a methacrylic group, an isocyanurate group, a phenyl group and a fluoro group.

The present invention is a method for producing a transparent polyimide film for a flexible display front plate containing metal oxide particles, a silane coupling agent, and polyimide, wherein the metal oxide particles, a silane coupling agent, and polyimide are used. The polyimide comprises a step of preparing a dope containing the solvent and a step of casting the dope onto a support to form a web, and the polyimide polymerizes the acid anhydride B and the diamine B. The polyimide is any of the polyimide obtained by polymerizing the acid anhydride C, the diamine C and the diamine D , and the metal oxide particles have an average primary particle size in the range of 10 to 100 nm. And the content is in the range of 20 to 70% by mass with respect to the total solid content (100% by mass) in the transparent polyimide film, and when the projected image of the transparent polyimide film is evaluated, it is on an 8-bit gray scale. A transparent polyimide film for the front plate of a flexible display that adjusts the standard deviation σ of gray value within the range of 0.50 to 1.10 and the occupied area ratio of the black part in the binarized image of the rectangular area to 50% or less. Manufacturing method can be provided .

Further, from the viewpoint of effectively removing water generated by dehydration condensation, it is preferable that the dope further contains an azeotropic dehydrating agent in the step of preparing the dope.

The present invention can provide an organic electroluminescence display including the transparent polyimide film.

Hereinafter, the present invention, its constituent elements, and modes and modes for carrying out the present invention will be described in detail. In the present application, "~" representing a numerical range is used to mean that the numerical values described before and after the numerical range are included as the lower limit value and the upper limit value.

《Transparent polyimide film》
The transparent polyimide film for the front plate of a flexible display of the present invention (hereinafter, also simply referred to as a polyimide film or a film) contains metal oxide particles, a silane coupling agent, and a polyimide, and the polyimide is the acid anhydride. A polyimide obtained by polymerizing B and the diamine B, and a polyimide obtained by polymerizing the acid anhydride C, the diamine C and the diamine D , and the average primary particle size of the metal oxide particles. Is in the range of 10 to 100 nm, and when the projected image of the transparent polyimide film is evaluated, the standard deviation σ of the gray value on the 8-bit gray scale is in the range of 0.50 to 1.10, and in the binarized image. It is characterized in that the occupied area ratio of the black portion is adjusted to 50% or less.
Here, "transparency" means that the total light transmittance of the film is 50% or more, preferably 70% or more, and more preferably 85% or more.

Hereinafter, a method for measuring the standard deviation σ of the gray value and the occupied area ratio of the black portion in the binarized image will be described.

<Standard deviation σ of gray value and occupied area ratio of black part in binarized image>

FIG. 1 is a schematic view showing a method for analyzing a projected image of the transparent polyimide film of the present invention.
First, the distance between the film sample 1 (transparent polyimide film) and the white light source 2 (S-light manufactured by Japan Technology Center Co., Ltd.) is adjusted to 60 cm, and the light from the white light source 2 with respect to the film sample 1 is emitted from an oblique direction of 45 °. Irradiate. The distance between the film sample 1 and the projection surface 3 arranged parallel to the film sample 1 is adjusted to 70 cm, and the shadow of the film sample 1 is projected onto the projection surface 3.
A camera 4 (for example, Canon EOS KISS 50, lens EF-S 18 = 55 mm, ISO sensitivity 100, aperture 5.6, shutter speed) arranged at a distance of 80 cm in a direction of 90 ° from the projection surface 3 of this projected image. Take a picture with 1/10 second, white balance manual setting) and obtain a shot image.
The white light source 2, the film sample 1, the projection surface 3, and the camera 4 are set to have the same height.
Next, for the obtained projected image, the standard deviation σ of the gray value and the occupied area ratio K (%) of the black portion in the binarized image are calculated according to the following procedures 1 to 7.

1. 1. The captured image is read into a personal computer using the free software ImageJ.
2. A rectangular evaluation area of 1 cm × 5 cm is set in the actual photographed image. At this time, the long side of the rectangle should be in the transport direction of the film sample.
3. 3. 8-bit grayscale is performed by free software ImageJ.
4. Background correction is performed by the free software ImageJ.
5. The standard deviation σ and the average value m of the gray value (pixel value) in the gray scale are calculated.
6. The rectangular evaluation area is binarized with the average value m as the threshold value.
7.2 The area of the black part (dark part) obtained by digitization is divided by the total area to calculate the occupied area ratio K (%) of the black part.

Here, the free software ImageJ is ImageJ1.32S created by WayneRasband.

Background correction is, for example, output as different brightness even though the right half and left half of the image have the same brightness, or gradually from the left side to the right side of the image. It is preferable to obtain the occupied area ratio K (%) of the black portion (dark portion) by performing histogram formation, average gradation calculation, and binarization processing when the output is performed as a result of brightening.

The standard deviation σ of the gray value on the gray scale is calculated by the following method.

N pieces of gray value data x ₁ , x ₂ , ..., X _N are used as a population, and the arithmetic mean (population average) m of the population is calculated by the following mathematical formula (1).

^{Next, the variance σ 2} is obtained by the following mathematical formula (2) using the population mean m obtained above.

Let the positive square root of this variance σ ^{2 be the standard deviation σ.}

The standard deviation σ of the gray value of the transparent polyimide film of the present invention on the gray scale is in the range of 0.50 to 1.10, but considering the range not visually recognized as unevenness and the productivity, 0.70 to 1. It is more preferably in the range of 05.

Further, the occupied area ratio of the black portion in the binarized image of the rectangular area of the transparent polyimide film of the present invention is adjusted to 50% or less, but considering the range not visually recognized as unevenness and the productivity, 40 to 50 It is preferably in the range of%, and more preferably in the range of 40 to 45%.

<Polyimide>
The polyimide according to the present invention is a resin having an imide structure, and is a polymer containing an imide bond in a repeating unit. The polyimide is preferably formed from a diamine or a derivative thereof and an acid anhydride or a derivative thereof.
Specifically, the polyimide is preferably a polyimide having a repeating unit represented by the following general formula (1). In the following general formula (1), the _{portion containing (-C (= O)) 2-} R- (C (= O)-) ₂ is a portion derived from an acid anhydride or a derivative thereof, and = NA-. The portion containing N = is a portion derived from diamine or a derivative thereof.

In the general formula (1), R consists of an aromatic hydrocarbon ring, an aromatic heterocycle, an aliphatic hydrocarbon having 4 to 39 carbon atoms, a tetravalent group derived from an alicyclic hydrocarbon, or a combination thereof. Represents a tetravalent group. A represents a divalent group consisting of a divalent aliphatic hydrocarbon having 1 to 39 carbon atoms, an alicyclic hydrocarbon or an aromatic hydrocarbon ring, or a combination thereof.

If R is a combination of any two or more of the above, they are -O-, -SO _2- , -CO-, -CH _2- , -C (CH ₃ ) _2- , -OSi (CH). ₃ ) From ₂ -,-(CH ₂ ) ₂ O-, -CF _2- , -C (CF ₃ ) _2- , -OSI (CF ₃ ) ₂ -,-(CF ₂ ) ₂ O- and -S- It may be linked via at least one linking group selected from the group.

Further, at least one hydrogen atom in the aromatic hydrocarbon ring represented by R, the aromatic heterocycle, the aliphatic hydrocarbon having 4 to 39 carbon atoms or the alicyclic hydrocarbon is a halogen atom (for example, a fluorine atom). , Chlorine atom, iodine atom, bromine atom, preferably fluorine atom), alkyl group having 1 to 8 carbon atoms (for example, methyl group, ethyl group, propyl group, isopropyl group, butyl group, sec-butyl group, tert-butyl Group, isobutyl group, isobutyl group, pentyl group, isopentyl group, neopentyl group, hexyl group, heptyl group, octyl group, 2-ethylhexyl group, etc.) or alkyl halide groups thereof (for example, monofluoromethyl group (-CFH)). ₂ ), difluoromethyl group (-CF ₂ H), trifluoromethyl group (-CF ₃ ), monofluoroethyl group (-CHF-CH ₃ , -CH _{2 -CH 2} F), difluoroethyl group (-CF ₂₎ -CH ₃ , -CHF-CH ₂ F, -CH _2- CHF ₂ ), etc.) may be substituted.

Examples of the aromatic hydrocarbon ring represented by R include a fluorene ring, a benzene ring, a biphenyl ring, a naphthalene ring, an azulene ring, an anthracene ring, a phenanthrene ring, a pyrene ring, a chrysene ring, a naphthacene ring, a triphenylene ring, o-. Terphenyl ring, m-terphenyl ring, p-terphenyl ring, acenaphthene ring, coronen ring, fluorantrene ring, naphthacene ring, pentacene ring, perylene ring, pentaphene ring, picene ring, pyrene ring, pyranthrene ring, anthra entre Rings and the like can be mentioned.

Examples of the aromatic heterocycle represented by R include a silol ring, a furan ring, a thiophene ring, an oxazole ring, a pyrrole ring, a pyridine ring, a pyridazine ring, a pyrimidine ring, a pyrazine ring, a triazine ring, an oxaziazole ring and a triazole ring. Ring, imidazole ring, pyrazole ring, thiazole ring, indole ring, benzimidazole ring, benzthiazole ring, benzoxazole ring, quinoxaline ring, quinazoline ring, phthalazine ring, thienothiophene ring, carbazole ring, azacarbazole ring (consisting of carbazole ring) Any one or more of the carbon atoms that make up the dibenzosilol ring, dibenzofuran ring, dibenzothiophene ring, benzothiophene ring or dibenzofuran ring are nitrogen atoms. Replaced ring, benzodifuran ring, benzodithiophene ring, aclysine ring, benzoquinoline ring, phenazine ring, phenanthridine ring, phenanthroline ring, cyclazine ring, kindrin ring, tepenidin ring, quinindrin ring, triphenodithiazine ring, triphenodi Oxazine ring, phenanthrazine ring, anthrazine ring, perimidine ring, naphthofuran ring, naphthophene ring, naphthodifuran ring, naphthodithiophene ring, anthrafran ring, anthradifuran ring, anthrathiophene ring, anthradithiophene ring, thianthene ring, Examples thereof include a phenoxatiin ring, a dibenzocarbazole ring, an indolocarbazole ring, and a dithienobenzene ring.

Examples of the tetravalent aliphatic hydrocarbon group having 4 to 39 carbon atoms represented by R include butane-1,1,4,4-triyl group and octane-1,1,8,8-triyl group. Decane-1,1,10,10-triyl groups and the like can be mentioned.

Examples of the tetravalent alicyclic hydrocarbon group having 4 to 39 carbon atoms represented by R include cyclobutane-1,2,3,4-tetrayl group and cyclopentane-1,2,4,5-tetrayl. Group, cyclohexane-1,2,4,5-tetrayl group, bicyclo [2.2.2] octo-7-en-2,3,5,6-tetrayl group, bicyclo [2.2.2] octane- 2,3,5,6-tetrayl group, 3,3', 4,4'-dicyclohexyltetrayl group, 3,6-dimethylcyclohexane-1,2,4,5-tetrayl group, 3,6-diphenylcyclohexane -1,2,4,5-tetrayl group and the like can be mentioned.

Above all, R is preferably groups R-1 to R-4 represented by the following structural formulas.

R is preferably groups R-1 to R-3, and particularly preferably groups R-1.

If A is a combination of any two or more of the above, they are -O-, -SO _2- , -CO-, -CH _2- , -C (CH ₃ ) _2- , -OSi (CH _3). ) ₂ -,-(CH ₂ ) ₂ O-, -CF _2- , -C (CF ₃ ) _2- , -OSI (CF ₃ ) ₂ -,-(CF ₂ ) ₂ O- and -S- It may be linked via at least one linking group selected from the group.

At least one hydrogen atom in the divalent aliphatic hydrocarbon group having 1 to 39 carbon atoms represented by A, the alicyclic hydrocarbon group or the aromatic hydrocarbon ring group is a halogen atom (for example, a fluorine atom, Chlorine atom, iodine atom, bromine atom, preferably fluorine atom), alkyl group with 1 to 8 carbon atoms (eg, methyl group, ethyl group, propyl group, isopropyl group, butyl group, sec-butyl group, tert-butyl group , Isobutyl group, isobutyl group, pentyl group, isopentyl group, neopentyl group, hexyl group, heptyl group, octyl group, 2-ethylhexyl group, etc.), or alkyl halide groups thereof (for example, monofluoromethyl group (-CFH _2)). ), Difluoromethyl group (-CF ₂ H), trifluoromethyl group (-CF ₃ ), monofluoroethyl group (-CHF-CH ₃ , -CH _{2 -CH 2} F), difluoroethyl group (-CF _2- It _{may be replaced with CH 3} , -CHF-CH ₂ F, -CH _2- CHF ₂ ), etc.).

Examples of the divalent aliphatic hydrocarbon group having 1 to 39 carbon atoms having or not having the linking group represented by A include groups A1-1 to A1-4 represented by the following structural formula. Can be mentioned.

In the above structural formula, m and n represent the number of repeating units. X represents an alkanediyl group having 1 to 3 carbon atoms.

The number of repeating units n is preferably an integer of 1 to 5, and more preferably an integer of 1 to 3.
X represents an alkanediyl group having 1 to 3 carbon atoms (methylene group, ethylene group, trimethylene group, propane-1,2-diyl group), and is preferably a methylene group.

Examples of the divalent alicyclic hydrocarbon group having 1 to 39 carbon atoms represented by A include groups A2-1 to A2-8 represented by the following structural formula.

Examples of the divalent aromatic hydrocarbon ring group having 1 to 39 carbon atoms having or not having the linking group represented by A include groups A3-1 to A3-12 represented by the following structural formula. Can be mentioned.

As a group composed of a combination of an aliphatic hydrocarbon group represented by A, an alicyclic hydrocarbon group and an aromatic hydrocarbon ring group, for example, groups A4-1 to A4-26 represented by the following structural formula are used. Can be mentioned.

Among them, A is preferably groups A4-7, A4-23, A4-25, A4-26, more preferably groups A4-7, A4-25, and preferably groups A4-25. Especially preferable.

Of these, the polyimide according to the present invention preferably has a fluorine atom from the viewpoint of efficiently removing water generated by dehydration condensation of the polyimide and a silane coupling agent.
From the above, it is preferable that the polyimide has a structure in which R is a group R-1 and A is a group A4-25.

When the polyimide is a fluoride polyimide, the content of fluorine atoms is not particularly limited, but is preferably about 1 to 40% by mass in the film. With such an amount, the obtained film has excellent transparency and is easy to perform heat correction by heat shrinkage.

The repeating unit represented by the general formula (1) is preferably in the range of 10 to 100 mol%, more preferably in the range of 50 to 100 mol%, and further preferably in the range of 80 to 100 mol% with respect to all the repeating units. It is within the range, particularly preferably within the range of 90 to 100 mol%.
The number of repeating units of the general formula (1) in one molecule of polyimide is in the range of 10 to 2000, preferably in the range of 20 to 200, and in this range, the glass transition temperature is further in the range of 230 to 350 ° C. It is preferably in the range of 250 to 330 ° C., and more preferably in the range of 250 to 330 ° C.

<Polyimide synthesis method>
The method for synthesizing the polyimide having the repeating unit represented by the general formula (1) is not particularly limited, and a known method can be applied. For example, to synthesize a polyimide by reacting an aromatic, aliphatic or alicyclic tetracarboxylic acid or a derivative thereof with a diamine or a derivative thereof to synthesize a polyamic acid, and imidizing the polyamic acid. Can be done.

Examples of the aromatic tetracarboxylic dian include 4,4'-biphthalic dianhydride, 4,4'-(hexafluoroisopropyridene) diphthalic acid anhydride, and 2,3,3', 4'-biphenyltetracarboxylic dian. Dianoxide, 4,4'-oxydiphthalic acid anhydride, 3,3', 4,4'-benzophenonetetracarboxylic dianhydride, 4- (2,5-dioxotetracarboxylic dianhydride) -1, 2,3,4-Tetrahydronaphthalene-1,2-dicarboxylic dianhydride, 3,3', 4,4'-diphenylsulfonetetracarboxylic dianhydride, 3,4'-oxydiphthalic dianhydride, 3,4 , 9,10-Perylenetetracarboxylic dianhydride (Pigment Red 224), 2,3,6,7-naphthalenetetracarboxylic dianhydride, 2,2-bis (4- (3,4-dicarboxyphenoxy) ) Phenyl) Propane dianhydride, 9,9-bis (3,4-dicarboxyphenyl) fluorene, 9,9-bis [4- (3,4-dicarboxyphenoxy) -phenyl] fluorene anhydride and the like. Be done.

Examples of the aliphatic tetracarboxylic acid include 1,2,3,4-butanetetracarboxylic acid.

Examples of the alicyclic tetracarboxylic acid include 1,2,3,4-cyclobutanetetracarboxylic dian, 1,2,4,5-cyclopentanetetracarboxylic dian, and 1,2,4,5-cyclohexanetetracarboxylic dian. , Bicyclo [2.2.2] Oct-7-ene-2,3,5,6-tetracarboxylic acid, Bicyclo [2.2.2] octane-2,3,5,6-tetracarboxylic acid, etc. Can be mentioned.

Examples of the aliphatic or alicyclic tetracarboxylic dian derivative include aliphatic or alicyclic tetracarboxylic acid esters, aliphatic or alicyclic tetracarboxylic dianhydride and the like.
Of the aliphatic or alicyclic tetracarboxylic acid, or a derivative thereof, an alicyclic tetracarboxylic dianhydride is preferable.

Here, the derivative is a compound that can be changed to an aliphatic or alicyclic tetracarboxylic acid. For example, in the case of an aliphatic tetracarboxylic acid dianhydride, a compound having two carboxy groups instead of the anhydride. , A compound in which one or both of these two carboxy groups are esterified, an acid chloride in which one or both of these two carboxy groups are chlorinated, and the like are preferably used.
By using such a compound (acyl compound), a polyimide film having high heat resistance and excellent optical properties and less coloring (yellowing) can be obtained.

Examples of the aliphatic tetracarboxylic acid esters include monoalkyl esters, dialkyl esters, trialkyl esters, and tetraalkyl esters of the above-mentioned aliphatic tetracarboxylic acids.

Examples of the alicyclic tetracarboxylic acid ester include monoalkyl ester, dialkyl ester, trialkyl ester and tetraalkyl ester of the alicyclic tetracarboxylic acid. The alkyl group moiety is preferably an alkyl group having 1 to 5 carbon atoms, and more preferably an alkyl group having 1 to 3 carbon atoms.

Examples of the aliphatic tetracarboxylic dianhydride include 1,2,3,4-butanetetracarboxylic dianhydride.

Examples of the alicyclic tetracarboxylic dianhydride include 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,4,5-cyclopentanetetracarboxylic dianhydride, 1,2. , 4,5-Cyclohexanetetracarboxylic dianhydride, Bicyclo [2.2.2] Oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, Bicyclo [2.2.2] Examples thereof include octane-2,3,5,6-tetracarboxylic dianhydride and 2,3,5-tricarboxycyclopentylacetic dianhydride. Particularly preferred is 1,2,4,5-cyclohexanetetracarboxylic dianhydride.

In general, in polyimide containing an aliphatic diamine as a constituent component, polyamic acid and diamine, which are intermediate products, form a strong salt. Therefore, in order to increase the molecular weight, a solvent having a relatively high salt solubility (for example, for example). Cresol, N, N-dimethylacetamide, γ-butyrolactone, N-methyl-2-pyrrolidone, etc.) are preferably used. However, even in the case of polyimide containing an aliphatic diamine as a constituent component, when 1,2,4,5-cyclohexanetetracarboxylic dianhydride is used as a constituent component, the polyamic acid and the diamine salt have a relatively weak bond. Since it is tied with, it is easy to increase the molecular weight and it is easy to obtain a flexible film.

In addition, for example, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 1,2,3,4-tetramethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, Tricyclo [6.4.0.02,7] dodecane-1,8: 2,7-tetracarboxylic dianhydride, 5- (2,5-dioxotetrahydrofuryl) -3-methyl-3-cyclohexene- 1,2-dicarboxylic dianhydride and the like can be used.

Further, an acid anhydride having a fluorene skeleton or a derivative thereof may be used. It has the effect of improving the coloring peculiar to polyimide. Examples of the acid anhydride having a fluorene skeleton include 9,9-bis (3,4-dicarboxyphenyl) fluorenic dianhydride and 9,9-bis [4- (3,4-dicarboxyphenoxy) phenyl. ] Fluorenic dianhydride, 9,9-bis [4- (3,4-dicarboxyphenoxy) -3-phenylphenyl] fluorenic dianhydride and the like can be used.

As the aromatic, aliphatic or alicyclic tetracarboxylic acid, or a derivative thereof, one type may be used alone, or two or more types may be used in combination.
Further, other tetracarboxylic dians or derivatives thereof (particularly acid dianhydride) may be used in combination as long as the solvent solubility of the polyimide, the flexibility of the polyimide film, the thermocompression bonding property, and the transparency are not impaired.

Examples of such other tetracarboxylic acids or derivatives thereof include pyromellitic acid, 3,3', 4,4'-biphenyltetracarboxylic acid, 2,3,3', 4'-biphenyltetracarboxylic acid, and the like. 2,2-bis (3,4-dicarboxyphenyl) propane, 2,2-bis (2,3-dicarboxyphenyl) propane, 2,2-bis (3,4-dicarboxyphenyl) -1,1 , 1,3,3,3-hexafluoropropane, 2,2-bis (2,3-dicarboxyphenyl) -1,1,1,3,3,3-hexafluoropropane, bis (3,4- Dicarboxyphenyl) sulfone, bis (3,4-dicarboxyphenyl) ether, bis (2,3-dicarboxyphenyl) ether, 3,3', 4,4'-benzophenone tetracarboxylic acid, 2,2', 3,3'-benzophenone tetracarboxylic acid, 4,4- (p-phenylenedioxy) diphthalic acid, 4,4- (m-phenylenedioxy) diphthalic acid, 1,1-bis (2,3-dicarboxy) Aromatic tetracarboxylic acids such as phenyl) ethane, bis (2,3-dicarboxyphenyl) methane, bis (3,4-dicarboxyphenyl) methane and their derivatives (particularly acid dianhydride), ethylene tetracarboxylic Examples thereof include aliphatic tetracarboxylic acids having 1 to 3 carbon atoms such as acids and derivatives thereof (particularly acid dianhydride).

Acid dianhydrides include 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropanedianhydride, biphenyltetracarboxylic dianhydride, pyromellitic dianhydride, and 4,4'-oxydiphthalic anhydride. Is preferable from the viewpoint of excellent transparency and easy heat correction by heat shrinkage. In addition, from the viewpoint of further suppressing yellowing and turbidity in an environment where temperature and humidity fluctuate (particularly in a high temperature and high humidity environment), 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropandian. Hydride is more preferred.

The portion (part derived from acid anhydride or its derivative) containing (-C (= O)) _2- R- (C (= O)-) _{2 in the above general formula (1) is used by being arbitrarily mixed.} However, the content of the above-mentioned preferable acid dianhydride-derived portion is preferably in the range of 50 to 100 mol%, and more preferably in the range of 80 to 100 mol%.

The diamine or a derivative thereof may be, for example, any of aromatic diamines, aliphatic diamines, isocyanic acid esters, and mixtures thereof, and aromatic diamines are preferable from the viewpoint of suppressing whitening of the polyimide film.
In the present invention, the aromatic diamine represents a diamine in which an amino group is directly bonded to an aromatic ring, and an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, or other substitutions are part of the structure thereof. It may contain a group (for example, a halogen atom, a sulfonyl group, a carbonyl group, an oxygen atom, etc.). Aliphatic diamine represents a diamine in which an amino group is directly bonded to an aliphatic hydrocarbon group or an alicyclic hydrocarbon group, and an aromatic hydrocarbon ring group and other substituents (for example, for example) are part of the structure thereof. , Halogen atom, sulfonyl group, carbonyl group, oxygen atom, etc.) may be contained.

Examples of aromatic diamines include, for example, p-phenylenediamine, m-phenylenediamine, 2,4-diaminotoluene, 2,6-diaminotoluene, benzidine, o-trizine, m-trizine, bis (trifluoromethyl). Benzidine, Octafluorobenzidine, 3,3'-dihydroxy-4,4'-diaminobiphenyl, 3,3'-dimethoxy-4,4'-diaminobiphenyl, 3,3'-dichloro-4,4'-diaminobiphenyl , 3,3'-difluoro-4,4'-diaminobiphenyl, 2,6-diaminonaphthalene, 1,5-diaminonaphthalene, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4' −Diaminodiphenylmethane, 4,4′-diaminodiphenylsulfone, 3,4′-diaminodiphenylsulfone, 4,4′-diaminobenzophenone, 2,2-bis (4- (4-aminophenoxy) phenyl) propane, 2, 2-Bis (4- (2-methyl-4-aminophenoxy) phenyl) propane, 2,2-bis (4- (2,6-dimethyl-4-aminophenoxy) phenyl) propane, 2,2-bis ( 4- (4-Aminophenoxy) phenyl) hexafluoropropane, 2,2-bis (4- (2-methyl-4-aminophenoxy) phenyl) hexafluoropropane, 2,2-bis (4- (2,6) -Dimethyl-4-aminophenoxy) phenyl) hexafluoropropane, 4,4'-bis (4-aminophenoxy) biphenyl, 4,4'-bis (2-methyl-4-aminophenoxy) biphenyl, 4,4' -Bis (2,6-dimethyl-4-aminophenoxy) biphenyl, 4,4'-bis (3-aminophenoxy) biphenyl, bis (4- (4-aminophenoxy) phenyl) sulfone, bis (4- (2) −Methyl-4-aminophenoxy) phenyl) sulfone, bis (4- (2,6-dimethyl-4-aminophenoxy) phenyl) sulfone, bis (4- (4-aminophenoxy) phenyl) ether, bis (4-) (2-Methyl-4-aminophenoxy) phenyl) ether, bis (4- (2,6-dimethyl-4-aminophenoxy) phenyl) ether, 1,4-bis (4-aminophenoxy) benzene, 1,4 -Bis (2-methyl-4-aminophenoxy) benzene, 1,4-bis (2,6-dimethyl-4-aminophenoxy) benzene, 1,3-bis (4-) Aminophenoxy) benzene, 1,3-bis (2-methyl-4-aminophenoxy) benzene, 1,3-bis (2,6-dimethyl-4-aminophenoxy) benzene, 2,2-bis (4-amino) Phenyl) propane, 2,2-bis (2-methyl-4-aminophenyl) propane, 2,2-bis (3-methyl-4-aminophenyl) propane, 2,2-bis (3-ethyl-4-aminophenyl) propane Aminophenyl) propane, 2,2-bis (3,5-dimethyl-4-aminophenyl) propane, 2,2-bis (2,6-dimethyl-4-aminophenyl) propane, 2,2-bis (4) -Aminophenyl) Hexafluoropropane, 2,2-bis (2-methyl-4-aminophenyl) hexafluoropropane, 2,2-bis (2,6-dimethyl-4-aminophenyl) hexafluoropropane, α, α'-bis (4-aminophenyl) -1,4-diisopropylbenzene, α, α'-bis (2-methyl-4-aminophenyl) -1,4-diisopropylbenzene, α, α'-bis (2) , 6-Dimethyl-4-aminophenyl) -1,4-diisopropylbenzene, α, α'-bis (3-aminophenyl) -1,4-diisopropylbenzene, α, α'-bis (4-aminophenyl) -1,3-diisopropylbenzene, α, α'-bis (2-methyl-4-aminophenyl) -1,3-diisopropylbenzene, α, α'-bis (2,6-dimethyl-4-aminophenyl) -1,3-diisopropylbenzene, α, α'-bis (3-aminophenyl) -1,3-diisopropylbenzene, 1,1-bis (4-aminophenyl) cyclopentane, 1,1-bis (2-) Methyl-4-aminophenyl) cyclopentane, 1,1-bis (2,6-dimethyl-4-aminophenyl) cyclopentane, 1,1-bis (4-aminophenyl) cyclohexane, 1,1-bis (2) -Methyl-4-aminophenyl) cyclohexane, 1,1-bis (2,6-dimethyl-4-aminophenyl) cyclohexane, 1,1-bis (4-aminophenyl) 4-methyl-cyclohexane, 1,1- Bis (4-aminophenyl) norbornan, 1,1-bis (2-methyl-4-aminophenyl) norbornan, 1,1-bis (2,6-dimethyl-4-aminophenyl) norbornan, 1,1-bis (4-Aminophenyl) Adamantane, 1,1-bis (2-methyl-4-aminophenyl) Adamantane, 1,1-bis (2,6-dimethyl-4-aminophenyl) Adamantane, 1,4-phenylenediamine, 3,3'-diaminobenzophenone, 2,2-bis (3-aminophenyl) hexafluoropropane , 3-Aminobenzylamine, 2,2-bis (3-amino-4-methylphenyl) hexafluoropropane, 1,3-bis (3-aminophenoxy) benzene, 2,2-bis [4- (4- (4- (4- (4-) 4-) Aminophenoxy) phenyl] propane, bis [4- (3-aminophenoxy) phenyl] sulfone, 1,3-bis [2- (4-aminophenyl) -2-propyl] benzene, bis (2-aminophenyl) sulfide , Bis (4-aminophenyl) sulfide, 1,3-bis (3-aminopropyl) tetramethyldisiloxane, 4,4'-diamino-3,3'-dimethyldiphenylmethane, 3,3'-diaminodiphenylmethane, 4 , 4'-ethylenedianiline, 4,4'-methylenebis (cyclohexylamine), 4,4'-methylenebis (2,6-diethylaniline), 4,4'-methylenebis (2-methylcyclohexylamine), 2, 2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl, 2,5-diethyl-4,6-dimethylbenzene-1,3-diamine, 4,4'-[isopropyridenebis [(4,4) 1-Phenylene) oxy]] Bisaniline, bis (aminomethyl) norbornan and the like can be mentioned.

Examples of the aliphatic diamine include ethylenediamine, hexamethylenediamine, polyethylene glycol bis (3-aminopropyl) ether, polypropylene glycol bis (3-aminopropyl) ether, 1,3-bis (aminomethyl) cyclohexane, and 1,4. -Bis (aminomethyl) cyclohexane, m-xylylene diamine, p-xylylene diamine, 1,4-bis (2-amino-isopropyl) benzene, 1,3-bis (2-amino-isopropyl) benzene, isophoronediamine , Norbornanamine, siloxanediamine, 4,4'-diaminodicyclohexylmethane, 3,3′-dimethyl-4,4′-diaminodicyclohexylmethane, 3,3′-diethyl-4,4′-diaminodicyclohexylmethane, 3, 3', 5,5'-Tetramethyl-4,4'-diaminodicyclohexylmethane, 2,3-bis (aminomethyl) -bicyclo [2.2.1] heptane, 2,5-bis (aminomethyl)- Bicyclo [2.2.1] heptane, 2,6-bis (aminomethyl) -bicyclo [2.2.1] heptane, 2,2-bis (4,4'-diaminocyclohexyl) propane, 2,2- Examples thereof include bis (4,4'-diaminomethylcyclohexyl) propane.

Further, a diamine having a fluorene skeleton or a derivative thereof may be used for the purpose of improving the coloring peculiar to polyimide.
Examples of the diamine having a fluorene skeleton or a derivative thereof include 9,9-bis [4- (4-aminophenoxy) phenyl] fluorene and 9,9-bis [4- (4-aminophenoxy) -3-phenylphenyl. ] Fluoren, 9,9-bis [4- (3-aminophenoxy) -3-phenylphenyl] fluorene, 9,9-bis [4- (2-aminophenoxy) -3-phenylphenyl] fluorene, 9,9 -Bis [4- (4-amino-3-methylphenoxy) -3-phenylphenyl] fluorene, 9,9-bis [4- (4-amino-2-methylphenoxy) -3-phenylphenyl] fluorene, 9 , 9-Bis [4- (4-amino-3-ethylphenoxy) -3-phenylphenyl] fluorene and the like.

Further, a diamine having a structure represented by the following general formula (2) having a triazine mother nucleus may be used.

In the general formula (2), R ¹ represents a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, or an aryl group. R ² represents an alkyl group or an aryl group having 1 to 12 carbon atoms. R ¹ and R ² may be the same or different.

The alkyl group having 1 to 12 carbon atoms represented by R ¹ is preferably an alkyl group having 1 to 10 carbon atoms, and more preferably an alkyl group having 1 to 6 carbon atoms.
An alkyl group having 1 to 12 carbon atoms represented by R ² is preferably an alkyl group having 1 to 10 carbon atoms, more preferably an alkyl group having 1 to 6 carbon atoms.

Specific examples of the alkyl group or aryl group having 1 to 12 carbon atoms represented by R ¹ and R ² include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, and a t-butyl group. Examples thereof include a phenyl group, a benzyl group, a naphthyl group, a methylphenyl group and a biphenyl group.

The aminoanilino group attached to the two NH groups of triazine is 4-aminoanilino or 3-aminoanilino, which may be the same or different, but 4-aminoanilino is preferable.

Specific examples of the diamine having a triazine mother nucleus and having a structure represented by the above general formula (2) include 2,4-bis (4-aminoanilino) -6-anilino-1,3,5-triazine. 2,4-bis (3-aminoanilino) -6-anilino-1,3,5-triazine, 2,4-bis (4-aminoanilino) -6-benzylamino-1,3,5-triazine, 2,4 -Bis (3-aminoanilino) -6-benzylamino-1,3,5-triazine, 2,4-bis (4-aminoanilino) -6-naphthylamino-1,3,5-triazine, 2,4-bis (4-Aminoanilino) -6-biphenylamino-1,3,5-triazine, 2,4-bis (4-aminoanilino) -6-diphenylamino-1,3,5-triazine, 2,4-bis (3) -Aminoanilino) -6-diphenylamino-1,3,5-triazine, 2,4-bis (4-aminoanilino) -6-dibenzylamino-1,3,5-triazine, 2,4-bis (4-aminoanilino) Aminoanilino) -6-Dinaphthylamino-1,3,5-triazine, 2,4-bis (4-aminoanilino) -6-N-methylanilino-1,3,5-triazine, 2,4-bis (4-) Aminoanilino) -6-N-methylnaphthylamino-1,3,5-triazine, 2,4-bis (4-aminoanilino) -6-methylamino-1,3,5-triazine, 2,4-bis (3) -Aminoanilino) -6-methylamino-1,3,5-triazine, 2,4-bis (4-aminoanilino) -6-ethylamino-1,3,5-triazine, 2,4-bis (3-aminoanilino) ) -6-Ethylamino-1,3,5-triazine, 2,4-bis (4-aminoanilino) -6-dimethylamino-1,3,5-triazine, 2,4-bis (3-aminoanilino)- 6-Dimethylamino-1,3,5-triazine, 2,4-bis (4-aminoanilino) -6-diethylamino-1,3,5-triazine, 2,4-bis (4-aminoanilino) -6-dibutyl Amino-1,3,5-triazine, 2,4-bis (4-aminoanilino) -6-amino-1,3,5-triazine, 2,4-bis (3-aminoanilino) -6-amino-1, Examples include 3,5-triazine.

Examples of the isocyanic acid ester which is a diamine derivative include diisocyanate obtained by reacting the above aromatic or aliphatic diamine with phosgene.

Examples of other diamine derivatives include diaminodisilanes, and examples thereof include trimethylsilylated aromatic or aliphatic diamines obtained by reacting the above aromatic or aliphatic diamines with chlorotrimethylsilane.

Diamines include 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl, 2,5-diethyl-4,6-dimethylbenzene-1,3-diamine, 4,4'-[isopropi]. Redenbis [(4,1-phenylene) oxy]] Bisaniline, bis (aminomethyl) norbornane is preferable. In addition, from the viewpoint of further suppressing yellowing and turbidity in an environment where temperature and humidity fluctuate (particularly in a high temperature and high humidity environment), 2,2'-bis (trifluoromethyl) -4,4'-diamino Biphenyl and bis (aminomethyl) norbornane are more preferable, and 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl is particularly preferable.

The portion (part derived from diamine or a derivative thereof) containing = N-AN = in the general formula (1) may be arbitrarily mixed and used, but the content of the preferred portion derived from diamine is It is preferably in the range of 20 to 80 mol% of the whole, and more preferably in the range of 40 to 60 mol%.

Polyamic acid is synthesized by reacting tetracarboxylic acid or its derivative with diamine or its derivative. Specifically, the polyamic acid is obtained by polymerizing at least one of the tetracarboxylic acids and at least one of the diamines in a suitable solvent.
The polyamic acid ester is formed by diesterifying tetracarboxylic dianhydride with an alcohol such as methanol, ethanol, isopropanol, or n-propanol, and reacting the obtained diester with a diamine in a suitable solvent. Can be obtained by Further, the polyamic acid ester can also be obtained by esterifying the carboxylic acid group of the polyamic acid obtained as described above by reacting with the alcohol as described above.

The reaction between the tetracarboxylic dianhydride and the diamine can be carried out under conventionally known conditions. The order and method of adding the tetracarboxylic dianhydride and the diamine are not particularly limited. For example, polycarboxylic acid can be obtained by adding tetracarboxylic dianhydride and diamine to a solvent in order and stirring at an appropriate temperature.
The amount of diamine is not particularly limited, and is preferably an amount that gives the above-mentioned preferable polyimide composition. Specifically, the amount of diamine is usually 0.8 mol or more, preferably 1 mol or more, with respect to 1 mol of tetracarboxylic dianhydride. On the other hand, it is usually 1.2 mol or less, preferably 1.1 mol or less. By setting the amount of diamine in such a range, the yield of the obtained polyamic acid can be improved.

Examples of the polymerization solvent used in this reaction include hydrocarbon solvents such as hexane, cyclohexane, heptane, benzene, toluene, xylene and mesitylen, carbon tetrachloride, dichloromethane, chloroform, 1,2-dichloroethane, chlorobenzene and dichlorobenzene. , Halogened hydrocarbon solvent such as fluorobenzene, ether solvent such as diethyl ether, tetrahydrofuran, 1,4-dioxane, methoxybenzene, ketone solvent such as acetone and methyl ethyl ketone, N, N-dimethylformamide, N, N- Amido solvents such as dimethylacetamide and N-methyl-2-pyrrolidone, aproton polar solvents such as dimethylsulfoxide and γ-butyrolactone, heterocyclic solvents such as pyridine, picolin, lutidine, quinoline and isoquinolin, phenols, cresols and the like. Examples thereof include, but are not particularly limited to. As the polymerization solvent, only one kind may be used, or two or more kinds of solvents may be mixed and used.

The concentrations of tetracarboxylic dianhydride and diamine in the solvent are appropriately set according to the reaction conditions and the viscosity of the polyamic acid solution. For example, the total mass of the tetracarboxylic dianhydride and the diamine is not particularly limited, but is usually 1% by mass or more, preferably 5% by mass or more, while usually 70% by mass, based on the total amount of the solution. Hereinafter, it is preferably 35% by mass or less. By setting the amount of the reaction substrate in such a range, polyamic acid can be obtained at low cost and in good yield.

The reaction temperature is not particularly limited, but is usually 0 ° C. or higher, preferably 20 ° C. or higher, while it is usually 100 ° C. or lower, preferably 80 ° C. or lower. The reaction time is not particularly limited, but is usually 1 hour or more, preferably 2 hours or more, while it is usually 100 hours or less, preferably 24 hours or less. By carrying out the reaction under such conditions, polyamic acid can be obtained at low cost and in good yield.

As the terminal group of the polyamic acid, the acid anhydride group and the amino group can be arbitrarily selected by excessively using either one of the tetracarboxylic dianhydride and the diamine at the time of the polymerization reaction.
When the terminal group is an acid anhydride group, the acid anhydride terminal may be left as it is without further treatment, or it may be hydrolyzed to obtain a dicarboxylic acid. Further, an alcohol having 4 or less carbon atoms may be used as an ester. In addition, monofunctional amines or isocyanates may be used to seal the ends. The amine or isocyanate used here is not particularly limited as long as it is a monofunctional primary amine or isocyanate. For example, aniline, methylaniline, dimethylaniline, trimethylaniline, ethylaniline, diethylaniline, triethylaniline, aminophenol, methoxyaniline, aminobenzoic acid, biphenylamine, naphthylamine, cyclohexylamine, phenylisocyanate, xylylene isocyanate, cyclohexylamine, Examples thereof include methylphenyl isocyanate and trifluoromethylphenyl isocyanate.

When the terminal group is an amino group, the terminal amino group can be sealed with a monofunctional acid anhydride to prevent the amino group from remaining at the terminal. The acid anhydride used here is not particularly limited as long as it is a monofunctional acid anhydride that becomes a dicarboxylic acid or a tricarboxylic acid when hydrolyzed. For example, maleic anhydride, methylmaleic anhydride, dimethylmaleic anhydride, succinic anhydride, norbornendicarboxylic acid anhydride, 4- (phenylethynyl) phthalic anhydride, 4-ethynylphthalic anhydride, phthalate. Acid anhydride, methylphthalic anhydride, dimethylphthalic anhydride, trimellitic anhydride, naphthalenedicarboxylic acid anhydride, 7-oxabicyclo [2.2.1] heptane-2,3-dicarboxylic acid anhydride, bicyclo [2.2.1] Heptane-2,3-dicarboxylic acid anhydride, bicyclo [2.2.2] Octa-5-ene-2,3-dicarboxylic acid anhydride, 4-oxatricyclo [5.2] .2.02,6] Undecane-3,5-dione, octahydro-1,3-dioxoisobenzofuran-5-carboxylic acid, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, dimethylcyclohexanedicarboxylic acid Anhydrides, 1,2,3,6-tetrahydrophthalic anhydrides, methyl-4-cyclohexene-1,2-dicarboxylic acid anhydrides and the like can be mentioned.

Next, a method of heating the polyamic acid (preferably in the form of a solution) obtained as described above to imidize the polyamic acid (thermal imidization method), or a ring-closing catalyst (imidization catalyst) in the polyamic acid solution. Polyimide can be obtained by a method of adding and imidizing a polyamic acid (chemical imidization method).
In the above thermal imidization method or chemical imidization method, the reaction kettle for polymerizing polyamic acid from the acid anhydride and diamine may be continuously imidized in the reaction kettle.

In the thermal imidization method in the reaction vessel, the polyamic acid in the polymerization solvent is used in a temperature range of, for example, 80 to 300 ° C. for 0.1 to 200 hours (preferably 1 to 100 hours, more preferably 3 to 50 hours). Time) Heat treatment to allow imidization to proceed. Further, the temperature range is preferably 150 to 200 ° C., and by setting the temperature to 150 ° C. or higher, imidization can be reliably advanced and completed, while by setting the temperature to 200 ° C. or lower, the solvent or the like can be used. It is possible to prevent an increase in resin concentration due to oxidation of unreacted raw materials and volatilization of a solvent.
Further, in the thermal imidization method, an azeotropic solvent can be added to the above-mentioned polymerization solvent in order to efficiently remove water generated by the imidization reaction. As the co-boiling solvent, for example, aromatic hydrocarbons such as toluene, xylene and solvent naphtha, and alicyclic hydrocarbons such as cyclohexane, methylcyclohexane and dimethylcyclohexane can be used. When an azeotropic solvent is used, the amount added is in the range of about 1 to 30% by mass, preferably 5 to 20% by mass, based on the total amount of the organic solvent.

On the other hand, in the chemical imidization method, a known ring closure catalyst is added to the polyamic acid in the polymerization solvent to promote imidization.
Specific examples of the ring-closing catalyst include aliphatic tertiary amines such as trimethylamine and triethylenediamine, and heterocyclic tertiary amines such as isoquinoline, pyridine, and picolin. Other examples thereof include substitution or absence. Substituted nitrogen-containing heterocyclic compounds, N-oxide compounds of nitrogen-containing heterocyclic compounds, substituted or unsubstituted amino acids, aromatic hydrocarbons having a hydroxy group or aromatic heterocyclic compounds, in particular 1,2-dimethyl. Lower alkyl imidazoles such as imidazole, N-methyl imidazole, N-benzyl-2-methyl imidazole, 2-methyl imidazole, 2-ethyl-4-methyl imidazole, 5-methylbenz imidazole, N-benzyl-2-methyl imidazole and the like. Imidazole derivative, isoquinoline, 3,5-dimethylpyridine, 3,4-dimethylpyridine, 2,5-dimethylpyridine, 2,4-dimethylpyridine, 4-n-propylpyridine and other substituted pyridines, p-toluenesulfonic acid. Etc. can be preferably used.
The amount of the ring-closing catalyst added is preferably in the range of 0.01 to 2 times equivalent, particularly in the range of 0.02 to 1 times equivalent with respect to the amic acid unit of the polyamic acid. By using a ring-closing catalyst, the physical characteristics of the obtained polyimide, particularly elongation and breaking resistance, may be improved.

Further, in the above thermal imidization method or chemical imidization method, a dehydrating agent may be added to the polyamic acid solution, and examples of such a dehydrating agent include an aliphatic acid anhydride such as acetic anhydride and phthal. Examples thereof include aromatic acid anhydrides such as acid anhydrides, which can be used alone or in combination. Further, it is preferable to use a dehydrating agent because the reaction can proceed at a low temperature. Although it is possible to imidize the polyamic acid only by adding a dehydrating agent to the polyamic acid solution, it is preferable to imidize the polyamic acid by heating or adding a ring-closing catalyst as described above because the reaction rate is slow. ..

The polyimide solution imidized in the reaction vessel in this way is advantageous because the molecular weight is less likely to decrease due to hydrolysis over time as compared with the polyimide solution. Further, since the imidization reaction has proceeded in advance, for example, in the case of polyimide having an imidization rate of 100%, imidization on the web becomes unnecessary and the drying temperature can be lowered.

Alternatively, the ring-closed polyimide may be reprecipitated and purified using a poor solvent such as methanol to form a solid, then dissolved in a solvent and cast-dried to form a film.
According to this method, it is possible to use different types of the polymerization solvent and the casting solvent, and by selecting the optimum solvent for each, it is possible to further bring out the performance of the polyimide film.
For example, in order to increase the molecular weight of polyamic acid, the polyamic acid is polymerized with dimethylacedamide, the ring is closed, solidified with methanol, dried, then redissolved in dichloromethane, cast and dried to increase the molecular weight. And low temperature drying is possible.
When dichloromethane is used as the solvent, it can be used in combination with other solvents. For example, auxiliary solvents such as tetrahydrofuran (THF), dioxolane, cyclohexanone, cyclopentanone, γ-butyrolactone, ethanol, methanol, butanol, and iropropanol can be appropriately used.

In addition to the above-mentioned polyimide, a polyimide containing atoms such as phosphorus, silicon, and sulfur can also be used.
For example, as the polyimide containing phosphorus, the polyimides described in paragraphs [0010]-[0021] of JP2011-74209A and paragraphs [0011]-[0025] of JP2011-074177 are used. Can be done.
As the polyimide containing silicon, the polyimide obtained by imidizing the polyimide precursor described in paragraphs [0030]-[0045] of JP2013-028996A can be used.
Examples of the polyimide containing sulfur include paragraphs [0009]-[0025] of JP2010-189322A, paragraphs [0012]-[0025] of JP2008-274234, and paragraphs of JP2008-274229. The polyimide obtained by imidizing the polyimide precursor described in [0012]-[0023] can be used.
In addition, the alicyclic polyimide described in paragraphs [0008]-[0012] of JP2009-256590 and paragraphs [0008]-[0012] of JP2009-256589 are preferably used. it can.

In addition to the above-mentioned polyimide, polyamide-imide can also be used. Polyamideimide contains a tricarboxylic acid, a tetracarboxylic acid or a dicarboxylic acid as an acid component, and a diamine as a constituent unit as an amine component.

Polyamideimide has the following a) to c) as acid components.

a) Tricarboxylic acid: trimellitic acid, diphenyl ether-3,3', 4'-tricarboxylic acid, diphenylsulfone-3,3', 4'-tricarboxylic acid, benzophenone-3,3', 4'-tricarboxylic acid, naphthalene Monoanhydrides such as -1,2,4-tricarboxylic acids, tricarboxylic acids such as butane-1,2,4-tricarboxylic acids, singles such as esterified products, or a mixture of two or more.

b) Tetetracarboxylic acid: 3,3,4', 4'-benzophenonetetracarboxylic acid, 3,3,4', 4'-biphenyltetracarboxylic acid, diphenylsulfone-3,3', 4,4'-tetra Carcarboxylic acid, naphthalene-2,3,6,7-tetracarboxylic acid, naphthalene-1,2,4,5-tetracarboxylic acid, naphthalene-1,4,5,8-tetracarboxylic acid, butane-1,2 , 3,4-tetracarboxylic acid, cyclopentane-1,2,3,4-tetracarboxylic dianhydride, dianhydride, esterified product, etc. alone or a mixture of two or more kinds.

c) Dicarboxylic acid: adipic acid, azelaic acid, sebacic acid, dicarboxylic acid of cyclohexane-4,4'-dicarboxylic acid, and their monoanhydrides and esterified products.

The amine components include 3,3'-dimethyl-4,4'-diaminobiphenyl, 3,3'-diethyl-4,4'-diaminobiphenyl, and 2,2'-dimethyl-4,4'-diamino. Biphenyl, 2,2'-diethyl-4,4'-diaminobiphenyl, 3,3'-dimethoxy-4,4'-diaminobiphenyl, 3,3'-diethoxy-4,4'-diaminobiphenyl, p-phenylene Diamine, m-phenylenediamine, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylsulfone, 3,3′-diaminodiphenylsulfone, 3,4′-diaminobiphenyl, 3 , 3'-diaminobiphenyl, 3,3'-diaminobenzanilide, 4,4'-diaminobenzanilide, 4,4'-diaminobenzophenone, 3,3'-diaminobenzophenone, 3,4'-diaminobenzophenone, 2 , 6-Tolylene diamine, 2,4-Tolylene diamine, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfide, 4,4'-diaminodiphenylpropane, 3,3'-diaminodiphenylpropane , 3,3'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, p-xylene diamine, m-xylene diamine, 2,2'-bis (4-aminophenyl) propane, 1,3-bis (3-amino) Phenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) benzene, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, bis [ 4- (4-Aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] propane, 4,4'-bis (4-amino) Phenoxy) biphenyl, 4,4'-bis (3-aminophenoxy) biphenyl, tetramethylenediamine, hexamethylenediamine, isophoronediamine, 4,4'-dicyclohexylmethanediamine, cyclohexane-1,4-diamine, diaminosiloxane, 1 , 5-Naphthalenediamine or the corresponding diisocyanates alone or in admixture of two or more.

In particular, as acid components, trimellitic anhydride (TMA), 3,3,4', 4'-benzophenonetetracarboxylic dianhydride (BTDA), and 3,3,4', 4'-biphenyltetracarboxylic acid. It is preferably a polyamide-imide polymerized with a raw material containing dianhydride (BPDA) and 1,5-naphthalenedi isocyanate (NDI) as an isocyanate component.

The value of the mol ratio of the imide bond to the amide bond of the polyamide-imide is preferably in the range of 99/1 to 60/40, more preferably in the range of 99/1 to 75/25, and further preferably in the range of 90 /. It is in the range of 10 to 80/20. When the mol ratio value of the imide bond and the amide bond is 60/40 or more, the heat resistance, the moisture resistance reliability, and the heat resistance reliability are improved. Further, when it is 99/1 or less, the elastic modulus tends to be low, and the folding resistance characteristics and the bending characteristics tend to be improved.

In addition to the above-mentioned polyimide, a repeating unit represented by the following formula (3) is an essential component, and at least one selected from the groups represented by the following general formulas (4), (5) and (6). Polyamideimide contained in the molecular chain with the seed structure as a repeating unit can also be used.

In the general formula (4), X represents an oxygen atom, CO, SO ₂ or a single bond. n is 0 or 1.

In the general formula (5), Y represents an oxygen atom, CO, OOC-R ^3- COO or a single bond. R ³ represents a divalent organic group. n is 0 or 1.

Here, in the general formula (4), X _{is preferably SO 2} or a single bond (biphenyl bond), or n = 0, and X is a bond (biphenyl bond), or n. It is more preferable that = 0.

In the formula (6), Y is preferably a benzophenone type (Y = CO) or a single bond type (biphenyl bond type, Y = single bond).

In one preferred embodiment, formula (3) is a repeating unit from trimellitic anhydride and 1,5-naphthalenediocyanate, general formula (4) is a repeating unit from terephthalic acid and 1,5-naphthalenediocyanate, a general formula. (5) is a repeating unit from biphenyltetracarboxylic dianhydride or benzophenonetetracarboxylic dianhydride and 1,5-naphthalenediocyanate, and the content ratio is the formula (3) / {general formula (4) + general. Formula (5) + formula (6)} = 1/99 to 40/60 mol ratio, and general formula (4) / general formula (5) = 10/90 to 90/10 mol ratio is preferable.

The higher the imidization rate is, the more preferable it is, and the upper limit thereof is 100%. The above-mentioned polyamide-imide can be synthesized by a usual method. For example, the isocyanate method, the amine method (acid chloride method, low temperature solution polymerization method, room temperature solution polymerization method, etc.) are used. In the present invention, the polyamide-imide is preferably soluble in an organic solvent, and is preferably synthesized by the isocyanate method. .. Also, industrially, it is preferable because the solution at the time of polymerization can be applied as it is.

In addition to the above-mentioned polyimide, a polyamide-imide containing a repeating unit represented by the following general formula (7) can also be used.

In the general formula (7), R ⁴ represents an aryl group or a cycloalkane radical.
At this time, the aryl group or the cycloalkane group may further contain at least one atom of a nitrogen atom, an oxygen atom, a sulfur atom and a halogen atom.

Examples of the diamine component that the polyamideimide can contain include p-phenylenediamine, m-phenylenediamine, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfone, and 3,3'. −Diaminodiphenylsulfone, 3,4′-diaminobiphenyl, 3,3′-diaminobiphenyl, 3,3′-diaminobenzanilide, 4,4′-diaminobenzanilide, 4,4′-diaminobenzophenone, 3,3 ′ -Diaminobenzophenone, 3,4′-diaminobenzophenone, 2,6-tolylene diamine, 2,4-tolylene diamine, 4,4′-diaminodiphenylsulfide, 3,3′-diaminodiphenylsulfide, 4,4 ′ -Diaminodiphenylpropane, 3,3′-diaminodiphenylpropane, 3,3′-diaminodiphenylmethane, 4,4′-diaminodiphenylmethane, p-xylene diamine, m-xylene diamine, 1,4-naphthalenediamine, 1, 5-naphthalenediamine, 2,6-naphthalenediamine, 2,7-naphthalenediamine, 2,2'-bis (4-aminophenyl) propane, 1,3-bis (3-aminophenoxy) benzene, 1,3- Bis (4-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) benzene, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, bis [4- (4-aminophenoxy) Phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] propane, 4,4'-bis (4-aminophenoxy) biphenyl, 4,4' -Bis (3-aminophenoxy) biphenyl, 3,3'-dimethyl-4,4'-diaminobiphenyl, 4-methyl-1,3-phenylenediamine, 3,3'-diethyl-4,4'-diaminobiphenyl , 2,2'-dimethyl-4,4'-diaminobiphenyl, 2,2'-diethyl-4,4'-diaminobiphenyl, 3,3'-dimethoxy-4,4'-diaminobiphenyl, 3,3'-Diethoxy-4,4'-diaminobiphenyl, trans-1,4-diaminocyclohexane, cis-1,4-diaminocyclohexane, 1,4-diaminocyclohexane (trans / cis mixture), 1,3-diaminocyclohexane, dicyclohexyl Methan-4,4'-diamine (trans form, cis form) , Trans / cis mixture), isophoronediamine, 1,4-cyclohexanebis (methylamine), 2,5-bis (aminomethyl) bicyclo [2.2.1] heptane, 2,6-bis (aminomethyl) bicyclo [2.2.1] Heptan, 3,8-bis (aminomethyl) tricyclo [5.2.1.0] Decane, 1,3-diaminoadamantan, 4,4'-methylenebis (2-methylcyclohexylamine) , 4,4'-Methylenebis (2-ethylcyclohexamamine), 4,4'-Methylenebis (2,6-dimethylcyclohexamine), 4,4'-Methylenebis (2,6-diethylcyclohexylamine), 2,2 -Bis (4-aminocyclohexyl) propane, 2,2-bis (4-aminocyclohexyl) hexafluoropropane, 1,3-propanediamine, 1,4-tetramethylenediamine, 1,5-pentamethylenediamine, 1, 6-Hexamethylenediamine, 1,7-Heptamethylenediamine, 1,8-octamethylenediamine, 1,9-nonamethylenediamine, etc. alone or a mixture of two or more, or the corresponding diisocyanate, etc. alone or 2 A mixture of seeds or more can be used as the diamine component.
Preferably, 3,3'-dimethyl-4,4'-diaminobiphenyl, dicyclohexylmethane-4,4'-diamine (trans-form, cis-form, trans / cis mixture), 4,4'-diaminodiphenyl ether, p. -A single or a mixture of two or more kinds of phenylenediamine, 4-methyl-1,3-phenylenediamine and the like, or a single or a mixture of two or more kinds of diisocyanates corresponding thereto can be used as a diamine component.
More preferably, 3,3'-dimethyl-4,4'-diaminobiphenyl, dicyclohexylmethane-4,4'-diamine (trans-form, cis-form, trans / cis mixture), 4,4'-diaminodiphenyl ether, A single or a mixture of two or more kinds such as 4-methyl-1,3-phenylenediamine, or a single or a mixture of two or more kinds such as diisocyanate corresponding thereto can be used as a diamine component.
More preferably, 3,3'-dimethyl-4,4'-diaminobiphenyl, dicyclohexylmethane-4,4'-diamine (trans-form, cis-form, trans / cis mixture), 4-methyl-1,3- A single or a mixture of two or more kinds such as phenylenediamine, or a single or a mixture of two or more kinds such as diisocyanate corresponding thereto can be used as a diamine component.

Among the above acid components and diamine components, the following components are preferable from the viewpoint of heat resistance, solvent resistance, and durability in the film forming process, and heat resistance, surface smoothness, and transparency of the produced polyamide-imide film. Used.
As the acid component, cyclohexane-1,2,4-tricarboxylic acid-1,2-anhydrous can be used.
As the diamine component, at least one or two compounds selected from the group consisting of 3,3'-dimethyl-4,4'-diaminobiphenyl and 4-methyl-1,3-phenylenediamine, or 3,3'-. At least one or two compounds selected from the group consisting of dimethyl-4,4'-diisocyanate biphenyl (o-trizine diisocyanate) and 4-methyl-1,3-phenylenediocyanate (tolylene diisocyanate) can be used. ..

Further, as a preferable polyamide-imide, a compound containing a repeating unit represented by the following general formula (8) can be used.

In the general formula (8), R ⁵ and R ⁶ independently represent a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or an aryl group, respectively.
At this time, the alkyl group or the aryl group may further contain at least one atom of a nitrogen atom, an oxygen atom, a sulfur atom and a halogen atom.

^{Examples of the aryl group represented by R 5} and R ⁶ in the general formula (8) include a phenyl group, a benzyl group, a naphthyl group, a methylphenyl group, a biphenyl group and the like.

When the total acid component is 100 mol%, the exemplified acid component is preferably contained in the range of 50 to 100 mol%, and more preferably contained in the range of 70 to 100 mol%.
When the total diamine component is 100 mol%, the illustrated diamine component is preferably contained in the range of 50 to 100 mol%, and more preferably contained in the range of 70 to 100 mol%.
Within these ranges, the heat resistance and durability in the film forming process are good, and the heat resistance, surface smoothness and transparency of the obtained polyamide-imide film are particularly good.

The molecular weight of the polyamide-imide used is, N- methyl-2-pyrrolidone (polymer concentration 0.5g ^/ cm 3), corresponds to the range of 0.3~2.5cm ³ / g and a logarithmic viscosity at 30 ° C. Those having a molecular weight of the above are preferable, and those having a molecular weight corresponding to the range of ^{0.5 to 2.0 cm 3 / g are more preferable.} If the logarithmic viscosity is 0.3 cm ³ / g or more, the mechanical properties will be sufficient when a molded product such as a film is formed. Further, when the logarithmic clay is 2.5 cm ³ / g or less, the solution viscosity does not become too high and the molding process becomes easy.

In addition to the above-mentioned polyimide, polyetherimide can also be used. Here, the polyetherimide is a thermoplastic resin containing an aromatic nucleus bond and an imide bond in its structural unit, and is not particularly limited. Specifically, it is represented by the following formula (9) or (10). It is preferably a polyetherimide having a repeating unit to be used.

Examples of the polyetherimide having a repeating unit represented by the above formula (9) include trade names "Ultem 1000" (glass transition temperature: 216 ° C.) and "Ultem 1010" (glass transition temperature: 216 ° C.) manufactured by General Electric Co., Ltd. ), Examples of the polyetherimide having a repeating unit represented by the above formula (10) include "Ultem CRS5001" (glass transition temperature Tg226 ° C.), and as another specific example, a trade name manufactured by Mitsui Kagaku Co., Ltd. Examples thereof include "Aurum (registered trademark) PL500AM" (glass transition temperature 258 ° C.).

The method for synthesizing the polyetherimide is not particularly limited, but usually, the amorphous polyetherimide having the repeating unit represented by the above formula (9) is 4,4'-[isopropyridenebis (p.). -Phenyleneoxy)] As a polycondensate of diphthalic acid dianhydride and m-phenylenediamine, and the polyetherimide having a repeating unit represented by the above formula (10) is 4,4'-[isopropylidene. Bis (p-phenyleneoxy)] It is synthesized by a method known as a polycondensate of diphthalic acid dianhydride and p-phenylenediamine.
Further, the polyetherimide may contain other copolymerizable monomer units such as an amide group, an ester group and a sulfonyl group as long as the gist of the present invention is not exceeded. As the polyetherimide, one type may be used alone or two or more types may be used in combination.

In addition to the above-mentioned polyimide, polyesterimide can also be used. Here, the polyesterimide is not particularly limited, but from the viewpoint of transparency and heat resistance, it is preferable that the polyesterimide structure represented by the following general formula (11) is contained in the constituent unit.

In the general formula (11), R ⁷ represents a divalent group. R ⁸ represents a divalent chain aliphatic group, a divalent cyclic aliphatic group or a divalent aromatic group.

The divalent chain aliphatic group, the divalent cyclic aliphatic group or the divalent aromatic group is a chain aliphatic compound having a divalent hydroxy group, respectively, and a ring fat having a divalent hydroxy group. It is desirable that the residue is derived from a diol such as a group compound or an aromatic compound having a divalent hydroxy group. Further, it may be a residue derived from a polycarbonate diol that can be polymerized from the above diol and carbonic acid esters, phosgene, or the like.

As the chain aliphatic compound having a divalent hydroxy group, a branched or linear diol having two hydroxy groups can be used. For example, alkylene diol, polyoxyalkylene diol, polyester diol, polycaprolactone diol and the like can be mentioned.

Examples of the alkylene diol include ethylene glycol, diethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, and the like. 1,6-Hexanediol, 1,8-octanediol, 2-methyl-1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,4-cyclohexanediol, 1,4- Cyclohexanedimethanol and the like can be mentioned.

Examples of the polyoxyalkylene diol include dimethylol propionic acid (2,2-bis (hydroxymethyl) propionic acid), dimethylolbutanoic acid (2,2-bis (hydroxymethyl) butanoic acid), polyethylene glycol, polypropylene glycol, and the like. Examples thereof include polytetramethylene glycol, polyoxytetramethylene glycol, and random copolymers of tetramethylene glycol and neopentyl glycol. Preferably, polyoxytetramethylene glycol is preferable.

Examples of the polyester diol include a polyester diol obtained by reacting a polyhydric alcohol exemplified below with a polybasic acid.
As the "multihydric alcohol component" used for the polyester diol, any various polyhydric alcohols can be used. For example, ethylene glycol, propylene glycol, 1,3-propanediol, 2-methyl-1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5. -Pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, diethylene glycol, dipropylene glycol, 2,2,4-trimethyl-1,3-pentanediol, cyclohexanedimethanol , Neopentyl hydroxypiparic acid ester, ethylene oxide adduct and propylene oxide adduct of bisphenol A, ethylene oxide adduct and propylene oxide adduct of hydrogenated bisphenol A, 1,9-nonanediol, 2-methyloctanediol, Polyether polyols such as 1,10-dodecanediol, 2-butyl-2-ethyl-1,3-propanediol, tricyclodecanedimethanol, polyethylene glycol, polypropylene glycol, and polytetramethylene glycol can be used.
As the polybasic acid component used in the polyester diol, any various polybasic acids can be used. For example, terephthalic acid, isophthalic acid, orthophthalic acid, 1,5-naphthalic acid, 2,6-naphthalic acid, 4,4'-diphenyldicarboxylic acid, 2,2'-diphenyldicarboxylic acid, 4,4'-diphenyletherdicarboxylic acid. Acid, adipic acid, sebacic acid, azelaic acid, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 4-methyl-1,2-cyclohexanedicarboxylic acid, dimer acid, etc. Fat group and alicyclic dibasic acids can be used.
Specific examples of commercially available polyester diols include ODX-688 (aliphatic polyester diol manufactured by DIC Co., Ltd .: adipic acid / neopentyl glycol / 1,6-hexanediol, number average molecular weight of about 2000), Vylon (registered). Trademark) 220 (polyester diol manufactured by Toyobo Co., Ltd., number average molecular weight of about 2000) and the like can be mentioned.

Examples of the polycaprolactone diol include polycaprolactone diol obtained by ring-opening addition reaction of lactones such as γ-butyllactone, ε-caprolactone and δ-valerolactone.

The above-mentioned chain aliphatic compounds having a divalent hydroxy group can be used alone or in combination of two or more.

Examples of the cyclic aliphatic compound having a divalent hydroxy group or the aromatic compound having a divalent hydroxy group include a compound having two hydroxy groups in an aromatic ring or a cyclohexane ring, and two phenols or an alicyclic alcohol. Compounds bonded with a divalent functional group, compounds having one hydroxy group in both nuclei of the biphenyl structure, compounds having two hydroxy groups in the naphthalene skeleton, and the like are used.

Compounds having two hydroxy groups on the aromatic ring and cyclohexane ring include hydroquinone, 2-methylhydroquinone, resorcinol, catechol, 2-phenylhydroquinone, cyclohexanedimethanol, tricyclodecanedimethanol, 1,4-dihydroxycyclohexane, and 1 , 3-Dihydroxycyclohexane, 1,2-dihydroxycyclohexane, 1,3-adamantandiol, dicyclopentadiene dihydrate, 2,3-dihydroxybenzoic acid, 2,4-dihydroxybenzoic acid, 2,5-dihydroxy Examples thereof include carboxyl group-containing diols such as benzoic acid, 2,6-dihydroxybenzoic acid, 3,4-dihydroxybenzoic acid, and 3,5-dihydroxybenzoic acid.

Compounds in which two phenols or alicyclic alcohols are bonded with a divalent functional group include 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxydiphenyl sulfone, and 4,4'-(9-fluorenylidene). Examples thereof include diphenol, 4,4'-dihydroxydicyclohexyl ether, 4,4'-dihydroxydicyclohexylsulfone, bisphenol A, bisphenol F, hydrogenated bisphenol A, hydrogenated bisphenol F and the like.

Compounds having one hydroxy group in both nuclei of the biphenyl structure include 4,4'-biphenol, 3,4'-biphenol, 2,2'-biphenol, 3,3', 5,5'-tetra. Examples thereof include methyl-4,4'-biphenol.

As the compound having two hydroxy groups in the naphthalene skeleton, 2,6-naphthalene diol, 1,4-naphthalene diol, 1,5-naphthalene diol, 1,8-naphthalene diol and the like can be used.

The number average molecular weight of the diol is preferably in the range of 100 to 30,000, more preferably in the range of 150 to 20,000, and even more preferably in the range of 200 to 10,000. When the number average molecular weight is in the above range, hygroscopicity, flexibility, mechanical properties, and colorless transparency can be sufficiently exhibited.

The polycarbonate diol may be a polycarbonate diol (copolymerized polycarbonate diol) having a plurality of types of alkylene groups in its skeleton. For example, a combination of 2-methyl-1,8-octanediol and 1,9-nonanediol, a combination of 3-methyl-1,5-pentanediol and 1,6-hexanediol, a combination of 1,5-pentanediol and 1 , Copolymerized polycarbonate diol that can be synthesized by a combination of 6-hexanediol and the like can be mentioned. Preferably, it is a copolymerized polycarbonate diol that can be synthesized from a combination of 2-methyl-1,8-octanediol and 1,9-nonanediol. Two or more of these polycarbonate diols can be used in combination.

Examples of commercially available polycarbonate diols that can be used include Kuraray polyol C series manufactured by Kuraray Co., Ltd. and Duranol series manufactured by Asahi Kasei Chemicals Co., Ltd. For example, Clare polyol C-1015N, Clare polyol C-1065N (carbonate diol manufactured by Clare Co., Ltd .: 2-methyl-1,8-octanediol / 1,9-nonanediol, number average molecular weight of about 1000), Clare polyol C -2015N, Clare Polyol C2065N (Carlate Diol Co., Ltd .: 2-Methyl-1,8-octanediol / 1,9-nonanediol, number average molecular weight about 2000), Clare polyol C-1050, Clare polyol C- 1090 (Carlate carbonate diol manufactured by Clare Co., Ltd .: 3-methyl-1,5-pentanediol / 1,6-hexanediol, number average molecular weight of about 1000), Clare polyol C-2050, Clare polyol C-2090 (Co., Ltd.) Claret carbonate diol: 3-methyl-1,5-pentanediol / 1,6-hexanediol, number average molecular weight: about 2000), Duranol T5650E (Polycarbonate diol manufactured by Asahi Kasei Chemicals Co., Ltd .: 1,5-pentanediol / 1) , 6-Hexanediol, number average molecular weight about 500), Duranol T5651 (Polycarbonate diol manufactured by Asahi Kasei Chemicals Co., Ltd .: 1,5-pentanediol / 1,6-hexanediol, number average molecular weight about 1000), Duranol T5652 (Asahi Kasei) Polycarbonate diols manufactured by Chemicals Co., Ltd .: 1,5-pentanediol / 1,6-hexanediol, number average molecular weight of about 2000) and the like can be mentioned. Preferably, it is Kuraray polyol C-1015N.

Examples of the method for synthesizing the polycarbonate diol include transesterification of the raw material diol and carbonic acid esters, and a dehydrochlorination reaction between the raw material diol and phosgene. Examples of the carbonic acid ester as a raw material include dialkyl carbonates such as dimethyl carbonate and diethyl carbonate, diaryl carbonates such as diphenyl carbonate, and alkylene carbonates such as ethylene carbonate and propylene carbonate.

^{The divalent group represented by R 7} in the general formula (11) is preferably a divalent group having a structure represented by the following general formulas (12), (13) or (14).

First, a divalent group having a structure represented by the general formula (12) will be described.

In the general formula (12), R ⁹ and R ¹⁰ each independently represent a divalent chain aliphatic group, a divalent cyclic aliphatic group or a divalent aromatic group, and a plurality of R ^9s are used. , They may be the same or different from each other. n is an integer of 1 or more.

The ^{divalent chain aliphatic group represented by R 9} and R ¹⁰ or the divalent ring aliphatic group or the divalent aromatic group is a divalent group represented by ^{R 8 in the general formula (11).} Examples thereof include chain aliphatic groups, divalent cyclic aliphatic groups, and divalent aromatic groups.
The ^{divalent chain aliphatic group represented by R 9} and R ¹⁰ or the divalent cyclic aliphatic group or the divalent aromatic group may be used alone or in combination of two or more.
m is a positive integer of 1 or more, but 2 or more is preferable, 3 or more is more preferable, and 4 or more is further preferable. The upper limit of m is not particularly limited, but is preferably 25 or less, more preferably 20 or less, and further preferably 10 or less. If it is 25 or less, the decrease in heat resistance can be suppressed.

Next, a divalent group having a structure represented by the general formula (13) will be described.

In the general formula (13), R ¹¹ has a single bond, an alkylene group (-C _n H _2n- ), a perfluoroalkylene group (-C _n F _2n- ), an ether bond (-O-), and an ester bond (-O-). COO-), carbonyl group (-CO-), sulfonyl group (-S (= O) _2- ), sulfinyl group (-SO-), sulfenyl group (-S-), carbonate group (-OCOO-) or Represents a fluorenylidene group. n is an integer of 1 or more. X ^{1 to} X ⁸ independently represent a hydrogen atom, a halogen atom or an alkyl group, and may be the same as or different from each other.

The upper limit of n in the general formula (13) is not particularly limited, but is preferably 10 or less, more preferably 5 or less, and further preferably 3 or less.

Specific examples of the divalent group having the structure represented by the general formula (13) are not particularly limited, but are diphenyl ether skeleton, diphenyl sulfone skeleton, 9-fluorenylidene diphenol skeleton, bisphenol A skeleton, and bisphenol F skeleton. , Ethylene oxide skeleton of bisphenol A, propylene oxide skeleton of bisphenol A, biphenyl skeleton, naphthalene skeleton and the like.

The group having the structure represented by the general formula (13) is preferably a residue derived from the compound having one hydroxy group in each of the two benzene rings in the general formula (13).
Examples of the raw material of the divalent group having the structure represented by the general formula (13) include 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxydiphenyl sulfone, and 4,4'-(9-fluorenylidene) diphenol. , Bisphenol A, bisphenol F, ethylene oxide adduct of bisphenol A, propylene oxide adduct of bisphenol A, 4,4'-biphenol, 3,4'-biphenol, 2,2'-biphenol, 3,3', 5 , 5'-Tetramethyl-4,4'-biphenol, 2,6-naphthalenediol, 1,4-naphthalenediol, 1,5-naphthalenediol, 1,8-naphthalenediol and the like can be used.
Preferably, it is an ethylene oxide adduct of 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxydiphenyl sulfone, 4,4'-(9-fluorenylidene) diphenol or bisphenol A. More preferably, it is an ethylene oxide adduct of 4,4'-dihydroxydiphenyl ether or bisphenol A.
These compounds can be used alone or in combination of two or more.
By using these materials, the R ⁷ position in Formula (11) can be introduced diphenyl ether skeleton or the like.

Next, a divalent group having a structure represented by the general formula (14) will be described.

In the general formula ^{(14), R 11 'is} a single bond, an alkylene group _{(-C n H 2n} -), perfluoroalkylene group _{(-C n F 2n} -), ether bond (-O-), an ester bond ( -COO-), carbonyl group (-CO-), sulfonyl group (-S (= O) _2- ), sulfinyl group (-SO-), sulfenyl group (-S-), carbonate group (-OCOO-) , Or represents a fluorenylidene group. n is an integer of 1 or more. ^X 1 ^{'~X 8'} are each independently a hydrogen atom, a halogen atom or an alkyl group, it may be the same as each other or may be different.

The upper limit of n in the general formula (14) is not particularly limited, but is preferably 10 or less, more preferably 5 or less, and further preferably 3 or less.

Specific examples of the divalent group having the structure represented by the general formula (14) are not particularly limited, but are dicyclohexyl ether skeleton, dicyclohexylsulfone skeleton, hydrogenated bisphenol A skeleton, hydrogenated bisphenol F skeleton, hydrogenated bisphenol skeleton. Examples thereof include the ethylene oxide adduct skeleton of A and the propylene oxide adduct skeleton of hydrogenated bisphenol A.

The divalent group having the structure represented by the general formula (14) is preferably a residue derived from a compound having one hydroxy group on each of the two cyclohexane rings in the general formula (14). Examples of the raw material of the divalent group having the structure represented by the general formula (14) include 4,4′-dihydroxydicyclohexyl ether, 4,4′-dihydroxydicyclohexylsulfone, hydrogenated bisphenol A, hydrogenated bisphenol F, and water. An ethylene oxide adduct of hydrogenated bisphenol A, a propylene oxide adduct of hydrogenated bisphenol A, and the like can be used.
Preferably, it is 4,4'-dihydroxydicyclohexyl ether or 4,4'-dihydroxydicyclohexylsulfone.
These compounds can be used alone or in combination of two or more.
By using these materials, the R ⁷ position in Formula (11), can be introduced dicyclohexyl ether skeleton or the like.

The polyesterimide having an esterimide structure represented by the general formula (11) is obtained, for example, by reacting a halide of cyclohexanetricarboxylic acid anhydride with diols to obtain an ester group-containing tetracarboxylic acid dianhydride, and then the ester group-containing tetracarboxylic acid dianhydride. It can be obtained by subjecting an ester group-containing tetracarboxylic acid dianhydride to a diamine, diisocyanate, or the like by a condensation reaction (imidization).

The polyesterimide may further contain a repeating unit represented by the following general formula (15).

In the general formula (15), R ¹² represents a divalent chain aliphatic group, a divalent cyclic aliphatic group or a divalent aromatic group.

The ^{divalent chain aliphatic group represented by R 12} or the divalent cyclic aliphatic group or the divalent aromatic group is a divalent chain formula represented by ^{R 8 in the general formula (11).} Examples thereof include an aliphatic group, a divalent cyclic aliphatic group or a divalent aromatic group, and R ^{8 in the general formula (11) and R 12} in the general formula (15) are the same. Or it may be different.

As R ¹² , a divalent chain aliphatic group, a divalent cyclic aliphatic group, or a divalent aromatic group may be used alone or in combination of two or more.

Heat resistance, flexibility, from the viewpoint of the balance of the low hygroscopicity, it is preferred that R ⁸ in the general formula (11) is a divalent group having a structure represented by the following general formula (16), also, ^{R 12} in the general formula (15) is preferably a divalent group having a structure represented by the following general formula (17).

In the general formula (16), R ¹³ has a single bond, an alkylene group (-C _n H _2n- ), a perfluoroalkylene group (-C _n F _2n- ), an ether bond (-O-), and an ester bond (-O-). It represents a COO−), a carbonyl group (−CO−), a sulfonyl group (−S (= O) ₂₋ ), a sulfinyl group (−SO−) or a sulfenyl group (−S−). n is an integer of 1 or more. X ^{9 to} X ¹⁶ independently represent a hydrogen atom, a halogen atom or an alkyl group, and may be the same or different.

Although n in the general formula (16) is an integer of 1 or more, it is preferably an integer of 1 to 10, more preferably an integer of 1 to 5, and even more preferably an integer of 1 to 3. ..

In the general formula ^{(17), R 13 'is} a single bond, an alkylene group _{(-C n H 2n} -), perfluoroalkylene group _{(-C n F 2n} -), ether bond (-O-), an ester bond ( Represents −COO−), carbonyl group (−CO−), sulfonyl group (−S (= O) ₂₋ ), sulfinyl group (−SO−) or sulfenyl group (−S−). n is an integer of 1 or more. ^X 9 ^{'~X 16'} are independently a hydrogen atom, a halogen atom or an alkyl group, it may be different even in the same.

Although n in the general formula (17) is an integer of 1 or more, it is preferably an integer of 1 to 10, more preferably an integer of 1 to 5, and even more preferably an integer of 1 to 3. ..

Formula (11) and the general formula (15), a divalent chain aliphatic group, R ⁸ positions of the general formula a divalent cycloaliphatic radical, or a divalent aromatic group (11) and the general formula in order to introduce the R ¹² position (15), it is preferable to use the corresponding diamine or diisocyanate component. That is, heat resistance is obtained by appropriately selecting a chain aliphatic diamine or a corresponding chain aliphatic diamine, a cyclic aliphatic diamine or a corresponding cyclic aliphatic diamine, an aromatic diamine or a corresponding aromatic diisocyanate. A polyesterimide having excellent properties, flexibility, and low moisture absorption can be obtained.
^{The diamine component of R 8} of the general formula (11) ^{and the diamine component of R 12} of the general formula (15) or the corresponding diisocyanate component may be the same or different, but are preferably the same.

Formula (11) R ⁸ and Formula (15) with R ¹² on the diamine component or the corresponding diisocyanate component thereto a basic skeleton of explaining.

Examples of the chain aliphatic diamine or the corresponding chain aliphatic diamine are 1,3-propanediamine, 1,4-tetramethylenediamine, 1,5-pentamethylenediamine, and 1,6-hexa. Examples thereof include methylenediamine, 1,7-heptamethylenediamine, 1,8-octamethylenediamine, and 1,9-nonamethylenediamine.
These can be used in combination of two or more.

Examples of the cyclic aliphatic diamine or the corresponding cyclic aliphatic diisocyanate include trans-1,4-diaminocyclohexane, cis-1,4-diaminocyclohexane, and 1,4-diaminocyclohexane (trans / cis). Mixture), 1,3-diaminocyclohexane, 4,4'-methylenebis (cyclohexylamine) (trans-form, cis-form, trans / cis mixture), isophoronediamine, 1,4-cyclohexanebis (methylamine), 2,5 -Bis (aminomethyl) bicyclo [2.2.1] heptane, 2,6-bis (aminomethyl) bicyclo [2.2.1] heptane, 3,8-bis (aminomethyl) tricyclo [5.2. 1.0] Decane, 1,3-diaminoadamantan, 4,4'-methylenebis (2-methylcyclohexylamine), 4,4'-methylenebis (2-ethylcyclohexylamine), 4,4'-methylenebis (2, 6-Dimethylcyclohexylamine), 4,4'-methylenebis (2,6-diethylcyclohexylamine), 2,2-bis (4-aminocyclohexyl) propane, 2,2-bis (4-aminocyclohexyl) hexafluoropropane And so on.
These can be used in combination of two or more.

Specific examples of the aromatic diamine or the corresponding aromatic diisocyanate include 2,2'-bis (trifluoromethyl) benzidine, p-phenylenediamine, m-phenylenediamine, 2,4- Diaminotoluene, 2,5-diaminotoluene, 2,4-diaminoxylene, 2,4-diaminodurene, 4,4'-diaminodiphenylmethane, 4,4'-methylenebis (2-methylaniline), 4,4'- Methylenebis (2-ethylaniline), 4,4'-methylenebis (2,6-dimethylaniline), 4,4'-methylenebis (2,6-diethylaniline), 4,4'-diaminodiphenyl ether, 3,4' −Diaminodiphenyl ether, 3,3′-diaminodiphenyl ether, 2,4′-diaminodiphenyl ether, 4,4′-diaminodiphenylsulfone, 3,3′-diaminodiphenylsulfone, 4,4′-diaminobenzophenone, 3,3′ −Diaminobenzophenone, 4,4′-diaminodiphenylsulfide, 3,3′-diaminodiphenylsulfide, 4,4′-diaminodiphenylpropane, 3,3′-diaminodiphenylpropane, 4,4′-diaminobenzanilide, p. -Xylenediamine, m-xylenediamine, 1,4-naphthalenediamine, 1,5-naphthalenediamine, 2,6-naphthalenediamine, 2,7-naphthalenediamine, benzidine, 3,3'-dihydroxybenzidine, 3,3 ′ -Dimethoxybenzidine, 3,3′-dimethyl-4,4′-diaminobiphenyl, 3,3′-diethyl-4,4′-diaminobiphenyl, 2,2′-dimethyl-4,4′-diaminobiphenyl, 2,2'-diethyl-4,4'-diaminobiphenyl, 3,3'-dimethoxy-4,4'-diaminobiphenyl, 3,3'-diethoxy-4,4'-diaminobiphenyl, o-trizine, m -Tridin, 1,4-bis (4-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,3-bis (3-aminophenoxy) benzene, 4,4'-bis (4) -Aminophenoxy) biphenyl, bis (4- (3-aminophenoxy) phenyl) sulfone, bis (4- (4-aminophenoxy) phenyl) sulfone, 2,2-bis (4- (4-aminophenoxy) phenyl) Propane, 2,2-bis (4- (4-aminophenoxy) phenyl) hex Examples thereof include safluoropropane, 2,2-bis (4-aminophenyl) hexafluoropropane, and diaminoterphenyl.
These can be used in combination of two or more.

From the viewpoint of the balance of heat resistance, flexibility, low moisture absorption, etc., the ^{preferred diamine component of R 8 of the general formula (11) and R 12} of the general formula (15) or the corresponding diisocyanate component is exemplified as a diamine. p-phenylenediamine, 2,4-diaminotoluene, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether, 1,5-naphthalenediamine, o-trizine, diaminoterphenyl, 4,4'-methylenebis ( Cyclohexylamine), a residue derived from isophorone diamine, etc. More preferably, it is a residue derived from 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether, 1,5-naphthalenediamine, o-tolidine, and even more preferably 4,4'-diaminodiphenylmethane. , 4,4'-Diaminodiphenyl ether, a residue derived from o-tolidine, most preferably a residue derived from 4,4'-diaminodiphenylmethane, o-tolidine.

<Metal oxide particles>
In the transparent polyimide film of the present invention, metal oxide particles having an average primary particle size in the range of 10 to 100 nm are contained in an amount of 20 to 70% by mass based on the total solid content (100% by mass) in the transparent polyimide film. It is characterized that it is contained within the range of.

The average primary particle size of the metal oxide particles is preferably in the range of 10 to 100 nm, and more preferably in the range of 30 to 100 nm. If the average primary particle size is smaller than 10 nm, the particles will aggregate, and if it is larger than 100 nm, the transparency of the film will decrease.
The average primary particle size is determined by observing the particles themselves using a laser diffraction scattering method, a dynamic light scattering method, or an electron microscope, or observing the particle image appearing on the cross section or surface of the refractive index layer with an electron microscope. It can be measured by using a conventionally known method such as a method. For example, the particle size of 1000 arbitrary particles is measured by the laser diffraction / scattering method specified in ISO13320, and d ₁ , d ₂ , and d 2, respectively. _{···, d i, ···, n} 1, n 2 particles having a particle size of _{d k,} respectively, · · _·, n i, · · ·, in a population of _{n k-number} the particles present, the particles 1 If the volume per individual was _{v i,} a volume average particle diameter _{mv = {Σ (v i ·} d i)} / {Σ (v i)} is calculated an average particle size weighted by the volume represented by can do.

The content of the metal oxide particles is in the range of 20 to 70% by mass, preferably in the range of 30 to 50% by mass, based on the total solid content (100% by mass) in the polyimide film. If the content is less than 20% by mass, the hardness (scratch resistance) of the film is insufficient, and if it is more than 70% by mass, the viscosity becomes too high during doping preparation, and the equipment load becomes large, resulting in film formation. Becomes difficult.

Examples of the metal oxide particles include silicon dioxide (silica), titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, and silicic acid. Examples thereof include fine particles such as aluminum, magnesium silicate, and calcium phosphate. Above all, it is preferable that silica is contained. This is because the refractive indexes of polyimide and silica are close to each other, and scattering is unlikely to occur, so that transparency is easily obtained.

As the silica, a synthetic product or a commercially available product may be used. Commercially available products include, for example, AEROSIL hydrophobic fumed silica series (AEROSIL R972, R974, R104, R106, R202, R208, R805, etc., AEROSIL is a registered trademark) sold by Nippon Aerosil Co., Ltd. Examples include the Snowtex series sold by Kagaku Kogyo Co., Ltd. (Snowtex OS, OXS, S, OS, 20, 30, 40, O, N, C, etc. Snowtex is a registered trademark).

<Silane coupling agent>
The transparent polyimide film of the present invention is characterized by containing a silane coupling agent.

As the silane coupling agent, a commercially available product or a synthetic product may be used.
Examples of commercially available products include the KBM series (KBM-1003, 303, 402, 1403, 502, 602, 903, etc.) and the KBE series (KBE-1003, 402, 502, etc.) sold by Shin-Etsu Chemical Co., Ltd. , 903, 585, etc.), and those sold by Toray Dow Corning Co., Ltd. and Momentive Performance Materials Co., Ltd.

Moreover, you may use a polymer silane coupling agent as a silane coupling agent. The polymer silane coupling agent refers to a reaction product of a polymerizable monomer and a silane coupling agent (silane compound). Such a polymer silane coupling agent can be obtained, for example, according to a method for producing a reaction product of a polymerizable monomer and a reactive silane compound disclosed in JP-A-11-116240.

Specifically, as the polymerizable monomer, (meth) acrylic acid, methyl (meth) acrylic acid, ethyl (meth) acrylic acid, (meth) acrylic acid-n-propyl, isopropyl (meth) acrylic acid, (meth)- n-butyl, isobutyl (meth) acrylate, -n-hexyl (meth) acrylate, cyclohexyl (meth) acrylate, -n-heptyl (meth) acrylate, -n-octyl (meth) acrylate, (meth) ) -2-ethylhexyl acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, phenyl (meth) acrylate, toluyl (meth) acrylate, benzyl (meth) acrylate, -2-methoxyethyl (meth) acrylate, -3-methoxybutyl (meth) acrylate, -2-hydroxyethyl (meth) acrylate, -2-hydroxypropyl (meth) acrylate, stearyl (meth) acrylate , (Meta) glycidyl acrylate, (meth) 2-aminoethyl acrylate, ethylene oxide adduct of (meth) acrylic acid, trifluoromethyl methyl (meth) acrylate, 2-trifluoromethyl ethyl (meth) acrylate , (Meta) 2-perfluoroethyl ethyl acrylate, (meth) 2-perfluoroethyl acrylate-2-perfluorobutyl ethyl, (meth) 2-perfluoroethyl acrylate, (meth) perfluoromethyl acrylate , (Meta) diverfluoromethylmethyl acrylate, (meth) 2-perfluoromethyl-2-perfluoroethylmethyl acrylate, 2-perfluorohexylethyl (meth) acrylate, 2-perfluoro (meth) acrylate (Meta) acrylic acid-based monomers such as decylethyl and 2-perfluorohexadecylethyl (meth) acrylate; styrene-based monomers such as styrene, vinyltoluene, α-methylcitylene, chlorostyrene, styrenesulfonic acid and salts thereof, per Fluorine-containing vinyl monomers such as fluoroethylene, perfluoropropylene and vinylidene fluoride, silicon-containing vinyl monomers such as vinyltrimethoxysilane and vinyltriethoxysilane, maleic anhydride, maleic acid, monoalkyl esters and dialkyl esters of maleic acid. , Fumaric acid, monoalkyl and dialkyl esters of fumaric acid, maleimide, methylmaleimide, ethylmaleimide, propylmaleimide, butylmaleimide, hexylmalei Nitrigen-containing vinyl monomers such as mid, octyl maleimide, dodecyl maleimide, stearyl maleimide, phenyl maleimide, cyclohexyl maleimide, amide group-containing vinyl monomers such as acrylamide and methacrylic, vinyl acetate, vinyl propionate, vinyl pivalate, benzoate Vinyl esters such as vinyl acid and vinyl silicate, alkenes such as ethylene and propylene, conjugated dienes such as butadiene and isoprene, vinyl chloride, vinylidene chloride, allyl chloride, allyl alcohol, acrylic resin monomers, pentaerythritol tri Acrylate, Pentaerythritol Tetraacrylate, Trimethylol Propantri (Meta) Acrylate, Pentaerythritol Tetraacrylate, Ditrimethylol Propanetetra (Meta) Acrylate, Dipentaerythritol Hexaacrylate, Methyl methacrylate, Ethyl methacrylate, Butyl methacrylate, Isobutyl methacrylate, 2- Ethylhexyl metecrylate, isodecyl metecrylate, n-lauryl acrylate, n-stearyl acrylate, 1,6-hexanediol dimethacrylate, perfluorooctyl ethyl methacrylate, trifluoroethyl metecrylate, urethane acrylate and the like, and mixtures thereof. Can be mentioned.
It is also possible to use polymers (oligomers, prepolymers) of these polymerizable monomers.
As the polymerizable monomer, one type may be used alone, or a plurality of types may be used. In the present invention, (meth) acrylic means acrylic or methacrylic, and (meth) acrylate means acrylate or methacrylate.

As the reactive silane compound, it is preferable to use an organosilicon compound having a structure represented by the following general formula (A).

General formula (A)
X-R-Si (OR) ₃

In the general formula (A), R represents an organic group having 1 to 10 carbon atoms selected from a substituted or unsubstituted hydrocarbon group. X represents one or more functional groups selected from (meth) acryloyl group, epoxy group (glycid group), urethane group, amino group and fluoro group.

Specific examples of the organic silicon compound having a structure represented by the general formula (A) include 3,3,3-trifluoropropyltrimethoxysilane and methyl-3,3,3-trifluoropropyldimethoxysilane. β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxymethyltrimethoxysilane, γ-glycidoxymethyltrioxysilane, γ-glycidoxyethyltrimethoxysilane, γ-glycidoxy Ethyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltriethoxysilane, γ- (β-) Glycydoxyethoxy) Propyltrimethoxysilane, γ- (meth) acrylooxymethyltrimethoxysilane, γ- (meth) acrylooxymethyltrioxysilane, γ- (meth) acrylooxyethyltrimethoxysilane, γ -(Meta) acrylooxyethyltriethoxysilane, γ- (meth) acrylooxypropyltrimethoxysilane, γ- (meth) acrylooxypropyltrimethoxysilane, γ- (meth) acrylooxypropyltriethoxysilane , Γ- (Meta) acrylooxypropyltriethoxysilane, 3-ureidoisopropylpropyltriethoxysilane, perfluorooctylethyltrimethoxysilane, perfluorooctylethyltriethoxysilane, perfluorooctylethyltriisopropoxysilane, trifluoro Propyltrimethoxysilane, N-β (aminoethyl) γ-aminopropylmethyldimethoxysilane, N-β (aminoethyl) γ-aminopropyltrimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, etc. and their products. Examples include mixtures.

A polymer silane coupling agent is synthesized by reacting a polymerizable monomer with a reactive silane compound.
As an example, an organic solvent solution prepared by mixing a reactive silane compound in the range of 0.5 to 20 parts by mass and further in the range of 1 to 10 parts by mass with respect to 100 parts by mass of the polymerizable monomer is prepared and polymerized. It can be obtained by adding an initiator and heating.

Examples of the organic solvent include aromatic hydrocarbons such as benzene, toluene and xylene, esters such as ethyl acetate and ethylene glycol monomethyl ether, ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone, and ethers such as tetrahydrofuran and dioxane. , Alcohols such as methanol and isopropanol, and halogenated hydrocarbons such as chloroform. These can also be mixed and used. The total concentration of the polymerizable monomer and the reactive silane compound at this time is preferably in the range of 1 to 40% by mass, more preferably in the range of 2 to 30% by mass as the solid content.

Examples of the polymerization initiator include azoisobutylnitrile, lauroyl peroxide, benzoyl peroxide, di-t-butyl peroxide, t-butylperoxy-2-ethylhexanoate, t-butylperoxyisobutyrate, and t-. Peroxide polymerization initiators such as butylperoxypivalate, t-butylperoxybenzoate, t-butylperoxyacetate, 2,2-azobisisobutyronitrile, 2,2-azobis (2,4-dimethyl) Valeronitrile), azo compounds such as 2,2-azobis (4-methoxy-2,4-dimethylvaleronitrile) and the like.

The reaction temperature is preferably in the range of 30 to 100 ° C., more preferably in the range of 50 to 95 ° C. If the reaction temperature is low, the reaction is slow and it may take too long to synthesize a polymer silane coupling agent having a large molecular weight, and if the reaction temperature is too high, the reaction rate becomes too fast, which is desired. It may not be possible to control the molecular weight of.

Further, from the viewpoint of reducing the influence during polyimide film formation by sufficiently slowing down the reaction rate of dehydration condensation, it is preferable to use a silane coupling agent that does not contain a group having a catalytic effect such as an amino group. ..
Further, it is preferable that the silane coupling agent has at least one group selected from an acrylic group, a methacrylic group, an isocyanurate group, a phenyl group and a fluoro group from the viewpoint of the effect of the present invention.

The content of the silane coupling agent is preferably in the range of 0.01 to 5 parts by mass, more preferably in the range of 0.1 to 3 parts by mass with respect to 100 parts by mass of the metal oxide particles.

<Aromatic compounds>
The transparent polyimide film of the present invention preferably further contains an aromatic compound.
The aromatic compound according to the present invention is a compound other than polyimide, which may have an aromatic ring in the molecule, and the parent (main) portion of the molecule has aromaticity. It does not have to be.

By containing an aromatic compound, a polyimide film having good production stability and reduced surface deformation failures can be obtained. Further, the retardation value Rt (nm) in the film thickness direction of the film can be reduced.

Aromatic compounds are compounds having a molecular weight or weight average molecular weight in the range of 300 to 10,000 and having an aromatic ring in the molecule. When the aromatic compound is a compound having a single structure, the molecular weight is used, and when it is an aggregate of compounds having a plurality of structures such as a polymer or an oligomer, the weight average molecular weight is used. If the molecular weight or the weight average molecular weight is less than 300, the amount of volatile components becomes too large during the production of the polyimide film, and the film itself tends to be impossible to produce. On the other hand, if the molecular weight or the weight average molecular weight is larger than 10,000, a large amount of aggregated foreign matter of the aromatic compound itself is generated, and the film itself tends to be impossible to produce.
Therefore, the fact that the molecular weight or weight average molecular weight of the aromatic compound is in the range of 300 to 10,000 indicates that a polyimide film can be substantially produced.

The weight average molecular weight of the aromatic compound can be measured by gel permeation chromatography. The measurement conditions are as follows.

Solvent: Dichloromethane Column: Shodex K806, K805, K803G (Three from Showa Denko KK are connected and used)
Column temperature: 25 ° C
Sample concentration: 0.1% by mass
Detector: RI Model 504 (manufactured by GL Science)
Pump: L6000 (manufactured by Hitachi, Ltd.)
Flow rate: 1.0 mL / min
Calibration curve: Standard polystyrene STK standard polystyrene (manufactured by Tosoh Corporation) A calibration curve with 13 samples in the range of Mw = 500 to 2800000 was used. The 13 samples are preferably used at approximately equal intervals.

The weight average molecular weight of the aromatic compound is preferably in the range of 400 to 10000, and more preferably in the range of 1000 to 5000.

The aromatic compound according to the present invention has an aromatic ring in the molecule. The aromatic compound preferably has two or more aromatic rings in the molecule, and more preferably four or more from the viewpoint of the effect of the present invention.

The content of the aromatic compound in the polyimide film is preferably in the range of 1 to 30% by mass from the viewpoint of the effect of the present invention. It is more preferable to contain it in the range of 15 to 30% by mass from the viewpoint that the retardation value Rt (nm) in the film thickness direction is small.

The aromatic compound is preferably a compound having an ether bond, an ester bond or an amide bond in the molecule from the viewpoint of improving compatibility with polyimide.

Further, a compound having a fluorene structure in the molecule is preferable from the viewpoint of the effect of the present invention.

Further, it is preferable that the compound has a structure represented by the following general formula (III) (details will be described later) from the viewpoint of the effect of the present invention.

(Aromatic compounds having an ether bond in the molecule)
As the aromatic compound having an ether bond in the molecule, a sugar ester having an aromatic ring in the molecule is preferable from the viewpoint of the effect of the present invention.
The sugar ester that can be used in the present invention is a compound having 1 to 12 furanose structures or pyranose structures, in which all or a part of the hydroxy groups in the compound are esterified, and an aromatic ring is formed in the molecule. It is preferably a compound having.

Preferred examples of such sugar esters include sucrose esters having a structure represented by the following general formula (I).

In the above general formula (I), R ^{14 to} R ²¹ each independently represent a hydrogen atom, a substituted or unsubstituted alkylcarbonyl group, or a substituted or unsubstituted arylcarbonyl group. R ^{14 to} R ²¹ may be the same as or different from each other. However, at least one substituent of ^{R 14 to} R ^{21 has an aromatic ring.}

^{The substituted or unsubstituted alkylcarbonyl group of R 14 to} R ²¹ of the general formula (I) is preferably a substituted or unsubstituted alkylcarbonyl group having 2 or more carbon atoms. Examples of the substituted or unsubstituted alkylcarbonyl group include a methylcarbonyl group (acetyl group). Examples of the substituent contained in the alkyl group include an aryl group such as a phenyl group.

The substituted or unsubstituted arylcarbonyl group is preferably a substituted or unsubstituted arylcarbonyl group having 7 or more carbon atoms. Examples of the arylcarbonyl group include a phenylcarbonyl group. Examples of the substituent contained in the aryl group include an alkyl group such as a methyl group and an alkoxy group such as a methoxy group.

The average degree of substitution of the acyl group in the sucrose ester is preferably in the range of 3.0 to 7.5.

Examples of other sugar esters include compounds described in JP-A No. 62-42996 and JP-A No. 10-237084.

(Aromatic compounds having an ester bond in the molecule)
As the aromatic compound having an intramolecular ester bond, the above-mentioned sugar ester and polyester are preferable from the viewpoint of compatibility.

As the polyester that can be used in the present invention, a polyester having a structure represented by the following general formula (II) is more preferable from the viewpoint of compatibility.

General formula (II)
B- (GA _{) n-GB}

In general formula (II), B represents a hydroxy group or a carboxylic acid residue. G represents an alkylene glycol residue having 2 to 12 carbon atoms, an aryl glycol residue having 6 to 12 carbon atoms, or an oxyalkylene glycol residue having 4 to 12 carbon atoms. A represents an alkylene dicarboxylic acid residue having 4 to 12 carbon atoms or an aryl dicarboxylic acid residue having 6 to 12 carbon atoms. n is an integer of 1 or more. However, at least one of A, B or G has an aromatic ring. )

Examples of the carboxylic acid component of the polyester having the structure represented by the general formula (II) include acetic acid, propionic acid, butyric acid, benzoic acid, paratarsial butyl benzoic acid, orthotoluic acid, metatoluic acid, paratoluic acid, and dimethyl benzoic acid. Acids, ethyl benzoic acid, normal propyl benzoic acid, amino benzoic acid, acetoxy benzoic acid, aliphatic acids and the like can be mentioned, and these can be used as one kind or a mixture of two or more kinds, respectively.

Examples of the alkylene glycol component having 2 to 12 carbon atoms of the polyester having the structure represented by the general formula (II) include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, and the like. 1,3-Butanediol, 1,2-propanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl-1,3-propane Diol (neopentyl glycol), 2,2-diethyl-1,3-propanediol (3,3-dimethylolpentane), 2-n-butyl-2-ethyl-1,3 propanediol (3,3-di) Methylol heptane), 3-methyl-1,5-pentanediol, 1,6-hexanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl-1,3-hexanediol, 2- Methyl-1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-octadecanediol and the like can be mentioned, and these glycols should be used as one kind or a mixture of two or more kinds. Can be done.

The aryl glycol component having 6 to 12 carbon atoms of the polyester having the structure represented by the general formula (II) includes 1,4-dihydroxybenzene, 1,3-dihydroxybenzene, 1,2-dihydroxybenzene, and 1,4. Examples thereof include −dihydroxynaphthalene, 1,3-dihydroxynaphthalene, 1,2-dihydroxynaphthalene, 1,4-benzenedimethanol, 1,3-benzenedimethanol, 1,2-benzenedimethanol and the like.

Examples of the oxyalkylene glycol component having 4 to 12 carbon atoms of the polyester having the structure represented by the general formula (II) include diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol and the like. , These glycols can be used as one or a mixture of two or more.

Examples of the alkylene dicarboxylic acid component having a structure represented by the general formula (II) and having 4 to 12 carbon atoms include succinic acid, maleic acid, fumaric acid, glutaric acid, adipic acid, azelaic acid, and sebacic acid. Dodecandicarboxylic acid and the like can be mentioned, and these can be used as one kind or a mixture of two or more kinds, respectively.

Examples of the aryldicarboxylic acid component of the polyester having a structure represented by the general formula (II) having 6 to 12 carbon atoms include phthalic acid, terephthalic acid, isophthalic acid, 1,5-naphthalenedicarboxylic acid, and 1,4-naphthalenedicarboxylic acid. Examples include acid.

The weight average molecular weight of the polyester having the structure represented by the general formula (II) is preferably in the range of 300 to 1500, more preferably in the range of 400 to 1000.
The acid value is 0.5 mgKOH / g or less, the hydroxy group (hydroxyl group) value is 25 mgKOH / g or less, more preferably the acid value is 0.3 mgKOH / g or less, and the hydroxy group (hydroxyl group) value is 15 mgKOH / g or less. ..

Hereinafter, specific compounds of polyester having a structure represented by the general formula (II) that can be used in the present invention are shown, but the present invention is not limited thereto.

(Aromatic compounds having an amide bond in the molecule)
It is preferable that the polyimide film of the present invention contains an aromatic compound having an amide bond in the molecule from the viewpoint of the effect of the present invention.
As the aromatic compound having an amide bond in the molecule, the compounds described in paragraphs 0136 to 0138 of JP-A-2014-153444 can be used.

(Aromatic compounds having a fluorene structure in the molecule)
It is preferable that the polyimide film of the present invention contains an aromatic compound having a fluorene structure in the molecule from the viewpoint of the effect of the present invention.
In particular, a compound having a 9,9-bisarylfluorene skeleton is more preferable from the viewpoint of improving the mechanical strength of the polyimide film.
As the aromatic compound having a fluorene structure in the molecule, the compounds described in paragraphs 0048 to 0053 of JP-A-2014-218657 can be used.

(Compound represented by general formula (III))
As the aromatic compound, it is preferable to use a compound having a structure represented by the following general formula (III) from the viewpoint of the effect of the present invention.

In the general formula (III), X represents a hetero atom or a carbon atom. Q represents a group of atoms required to form a substituted or unsubstituted aromatic heterocycle with a nitrogen atom and X. R ^{22 to} R ²⁵ each independently represent a hydrogen atom or a substituent.

Aromatic heterocycles are generally unsaturated heterocycles, preferably heterocycles with the most double bonds. The aromatic heterocycle is preferably a 5-membered ring, a 6-membered ring or a 7-membered ring, and more preferably a 5-membered ring or a 6-membered ring. The heteroatom of the aromatic heterocycle (including the heteroatom represented by X) is preferably N, S or O, and particularly preferably N.
The aromatic heterocycle is preferably a pyrrole ring, a pyrazole ring, an imidazole ring, a 1,2,3-triazole ring, a 1,2,4-triazole ring, or a 1,3,5-triazole ring. Of these, 1,2,3-triazole ring, 1,2,4-triazole ring, and 1,3,5-triazine ring are more preferable.

The aromatic heterocycle may have a substituent, and if a plurality of aromatic heterocycles are present, they may be the same or different, and they may be condensed to form a ring.

The substituents that the aromatic heterocycle may have and the ^{substituents represented by R 22 to} R ²⁵ include a halogen atom (for example, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom) and an alkyl group (preferably). Is an alkyl group having 1 to 30 carbon atoms, for example, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, a tert-butyl group, an n-octyl group, a 2-ethylhexyl group), a cycloalkyl group (preferably). , A substituted or unsubstituted cycloalkyl group having 3 to 30 carbon atoms, for example, a cyclohexyl group, a cyclopentyl group, a 4-n-dodecylcyclohexyl group), a bicycloalkyl group (preferably substituted or absent of 5 to 30 carbon atoms). It is a substituted bicycloalkyl group (a monovalent group obtained by removing one hydrogen atom from a bicycloalkane having 5 to 30 carbon atoms), for example, bicyclo [1,2,2] heptane-2-yl, bicyclo. [2,2,2] octane-3-yl), alkenyl group (preferably a substituted or unsubstituted alkenyl group having 2 to 30 carbon atoms, for example, vinyl group), cycloalkenyl group (preferably having 3 carbon atoms). It is a substituted or unsubstituted cycloalkenyl group of ~ 30 (a monovalent group obtained by removing one hydrogen atom of cycloalkene having 3 to 30 carbon atoms), for example, 2-cyclopenten-1-yl, 2-cyclohexene-. 1-yl group), bicycloalkenyl group (substituted or unsubstituted bicycloalkenyl group, preferably substituted or unsubstituted bicycloalkenyl group having 5 to 30 carbon atoms (1 hydrogen atom of bicycloalkene having one double bond) The monovalent group removed), for example, a bicyclo [2,2,1] hept-2-ene-1-yl group and a bicyclo [2,2,2] octo-2-en-4-yl group. ), An alkynyl group (preferably a substituted or unsubstituted alkynyl group having 2 to 30 carbon atoms, for example, an ethynyl group or a propargyl group), an aryl group (preferably a substituted or unsubstituted aryl group having 6 to 30 carbon atoms). One hydrogen atom from, for example, a phenyl group, a p-tolyl group, a naphthyl group), a heterocyclic group (preferably a 5- or 6-membered substituted or unsubstituted aromatic or non-aromatic heterocyclic compound. The removed monovalent group, more preferably a 5- or 6-membered aromatic heterocyclic group having 3 to 30 carbon atoms, such as 2-furyl group, 2-thienyl group, 2-pyrimidinyl group, 2-benzothiazolyl. Group), cyano group, hydroxy group, nitro group, carboxy group, alkoxy group (preferably 1 to 30 carbon atoms) An exchangeable or unsubstituted alkoxy group, for example, a methoxy group, an ethoxy group, an isopropoxy group, a tert-butoxy group, an n-octyloxy group, a 2-methoxyethoxy group), an aryloxy group (preferably having 6 to 6 carbon atoms). 30 substituted or unsubstituted aryloxy groups, for example, phenoxy group, 2-methylphenoxy group, 4-tert-butylphenoxy group, 3-nitrophenoxy group, 2-tetradecanoylaminophenoxy group), silyloxy group. (Preferably a silyloxy group having 3 to 20 carbon atoms, for example, a trimethylsilyloxy group, a tert-butyldimethylsilyloxy group), a heterocyclic oxy group (preferably a substituted or unsubstituted heterocyclic oxy group having 2 to 30 carbon atoms). Group, 1-phenyltetrazole-5-oxy group, 2-tetrahydropyranyloxy group), acyloxy group (preferably formyloxy group, substituted or unsubstituted alkylcarbonyloxy group having 2 to 30 carbon atoms, 6 to 6 carbon atoms. It is a substituted or unsubstituted arylcarbonyloxy group of 30, for example, a formyloxy group, an acetyloxy group, a pivaloyloxy group, a stearoyloxy group, a benzoyloxy group, a p-methoxyphenylcarbonyloxy group), a carbamoyloxy group (preferably). It is a substituted or unsubstituted carbamoyloxy group having 1 to 30 carbon atoms, for example, N, N-dimethylcarbamoyloxy group, N, N-diethylcarbamoyloxy group, morpholinocarbonyloxy group, N, N-di-n-. An octylaminocarbonyloxy group, an Nn-octylcarbamoyloxy group), an alkoxycarbonyloxy group (preferably a substituted or unsubstituted alkoxycarbonyloxy group having 2 to 30 carbon atoms, for example, a methoxycarbonyloxy group, an ethoxycarbonyloxy group). A group, a tert-butoxycarbonyloxy group, an n-octylcarbonyloxy group), an aryloxycarbonyloxy group (preferably a substituted or unsubstituted aryloxycarbonyloxy group having 7 to 30 carbon atoms, for example, a phenoxycarbonyloxy group. , P-methoxyphenoxycarbonyloxy group, pn-hexadecyloxyphenoxycarbonyloxy group), amino group (preferably amino group, substituted or unsubstituted alkylamino group having 1 to 30 carbon atoms, 6 to 30 carbon atoms). Substituent or unsubstituted anilino group, for example, amino group, methylamino group, dimethylamino group, anilino group, N-methyl-anili No group, diphenylamino group), acylamino group (preferably formylamino group, substituted or unsubstituted alkylcarbonylamino group having 1 to 30 carbon atoms, substituted or unsubstituted arylcarbonylamino group having 6 to 30 carbon atoms. , For example, formylamino group, acetylamino group, pivaloylamino group, lauroylamino group, benzoylamino group), aminocarbonylamino group (preferably substituted or unsubstituted aminocarbonylamino group having 1 to 30 carbon atoms, for example, carbamoylamino. A group, an N, N-dimethylaminocarbonylamino group, an N, N-diethylaminocarbonylamino group, a morpholinocarbonylamino group), an alkoxycarbonylamino group (preferably a substituted or unsubstituted alkoxycarbonylamino group having 2 to 30 carbon atoms). For example, methoxycarbonylamino group, ethoxycarbonylamino group, tert-butoxycarbonylamino group, n-octadecyloxycarbonylamino group, N-methyl-methoxycarbonylamino group), aryloxycarbonylamino group (preferably 7 to 7 carbon atoms). 30 substituted or unsubstituted aryloxycarbonylamino groups, for example, phenoxycarbonylamino group, p-chlorophenoxycarbonylamino group, mn-octyloxyphenoxycarbonylamino group), sulfamoylamino group (preferably). Substituent or unsubstituted sulfamoylamino groups having 0 to 30 carbon atoms, for example, sulfamoylamino groups, N, N-dimethylaminosulfonylamino groups, Nn-octylaminosulfonylamino groups), alkyl and An arylsulfonylamino group (preferably a substituted or unsubstituted alkylsulfonylamino having 1 to 30 carbon atoms, a substituted or unsubstituted arylsulfonylamino group having 6 to 30 carbon atoms, for example, a methylsulfonylamino group or a butylsulfonylamino group. Group, phenylsulfonylamino group, 2,3,5-trichlorophenylsulfonylamino group, p-methylphenylsulfonylamino group), mercapto group, alkylthio group (preferably substituted or unsubstituted alkylthio group having 1 to 30 carbon atoms). Yes, for example, a methylthio group, an ethylthio group, an n-hexadecylthio group), an arylthio group (preferably a substituted or unsubstituted arylthio group having 6 to 30 carbon atoms, for example, a phenylthio group, a p-chlorophenylthio group, m- Methoxyphenyl thio group), heterocyclic thio group (preferably 2 carbon atoms) ~ 30 substituted or unsubstituted heterocyclic thio group, for example, 2-benzothiazolylthio group, 1-phenyltetrazole-5-ylthio group), sulfamoyl group (preferably substituted or absence of 0 to 30 carbon atoms). Substituted sulfamoyl groups, such as N-ethylsulfamoyl group, N- (3-dodecyloxypropyl) sulfamoyl group, N, N-dimethylsulfamoyl group, N-acetylsulfamoyl group, N-benzoyl. Sulfamoyl group, N- (N'phenylcarbamoyl) sulfamoyl group), sulfo group, alkyl and arylsulfinyl groups (preferably substituted or unsubstituted alkylsulfinyl groups with 1 to 30 carbon atoms, substituted or absent from 6 to 30). Substituted arylsulfinyl groups, such as methylsulfinyl groups, ethylsulfinyl groups, phenylsulfinyl groups, p-methylphenylsulfinyl groups), alkyl and arylsulfonyl groups (preferably substituted or unsubstituted alkyls having 1 to 30 carbon atoms). A sulfonyl group, a 6-30 substituted or unsubstituted arylsulfonyl group, for example, a methylsulfonyl group, an ethylsulfonyl group, a phenylsulfonyl group, a p-methylphenylsulfonyl group), an acyl group (preferably a formyl group, carbon number of carbons). A 2 to 30 substituted or unsubstituted alkylcarbonyl group, a 7 to 30 carbon number substituted or unsubstituted arylcarbonyl group, for example, an acetyl group, a pivaloylbenzoyl group), an aryloxycarbonyl group (preferably carbon). Numbers 7 to 30 substituted or unsubstituted aryloxycarbonyl groups, for example, phenoxycarbonyl group, o-chlorophenoxycarbonyl group, m-nitrophenoxycarbonyl group, p-tert-butylphenoxycarbonyl group), alkoxycarbonyl group. (Preferably a substituted or unsubstituted alkoxycarbonyl group having 2 to 30 carbon atoms, for example, a methoxycarbonyl group, an ethoxycarbonyl group, a tert-butoxycarbonyl group, an n-octadecyloxycarbonyl group), a carbamoyl group (preferably a benzoyl group). 1 to 30 substituted or unsubstituted carbamoyl groups, for example, carbamoyl group, N-methylcarbamoyl group, N, N-dimethylcarbamoyl group, N, N-di-n-octylcarbamoyl group, N- (methylsulfonyl). ) Carbamoyl groups), aryl and heterocyclic azo groups (preferably substituted or unsubstituted arylazo groups having 6 to 30 carbon atoms, substituted or unsubstituted having 3 to 30 carbon atoms). Heterocyclic azo group, for example, phenylazo group, p-chlorophenylazo group, 5-ethylthio-1,3,4-thiadiazol-2-ylazo group), imide group (preferably N-succinimide group, N-phthalimide group). Group), phosphino group (preferably a substituted or unsubstituted phosphino group having 2 to 30 carbon atoms, for example, dimethylphosphino group, diphenylphosphino group, methylphenoxyphosphino group), phosphinyl group (preferably carbon number 2 to 30 substituted or unsubstituted phosphinyl groups, for example, phosphinyl group, dioctyloxyphosphinyl group, diethoxyphosphinyl group, phosphinyloxy group (preferably substituted or substituted with 2 to 30 carbon atoms). It is an unsubstituted phosphinyloxy group, for example, a diphenoxyphosphinyloxy group, a dioctyloxyphosphinyloxy group, a phosphinylamino group (preferably a substituted or unsubstituted phos having 2 to 30 carbon atoms). It is a finylamino group, for example, a dimethoxyphosphinylamino group, a dimethylaminophosphinylamino group), a silyl group (preferably a substituted or unsubstituted silyl group having 3 to 30 carbon atoms, for example, a trimethylsilyl group. , Tert-butyldimethylsilyl group, phenyldimethylsilyl group).

The compound having the structure represented by the general formula (III) preferably has a 1,2,3-triazole ring as the aromatic heterocycle represented by Q, and has a structure represented by the following general formula (IV). It is more preferable that it is a benzotriazole-based compound having.

In general formula (IV), G ¹ represents a hydrogen atom. G ² represents a hydrogen atom, a cyano group, a chlorine atom, a fluorine atom, -CF ₃ , -CO-G ³ , -SOE ³ or -SO ₂ E ³ . G ³ is a linear or branched alkyl group having 1 to 24 carbon atoms, a linear or branched alkenyl group having 2 to 18 carbon atoms, a cycloalkyl group having 5 to 12 carbon atoms, and a carbon number of carbon atoms. Represents a phenyl group or a phenylalkyl group having 1 to 4 alkyl groups having 1 to 4 carbon atoms as a phenylalkyl group, a phenyl group, or a substituent of 7 to 15.

E ¹ represents a phenyl alkyl group having 7 to 15 carbon atoms, a phenyl group, or a phenyl group or a phenyl alkyl group having 1 to 4 alkyl groups having 1 to 4 carbon atoms as a substituent.

E ² is a linear or branched alkyl group having 1 to 24 carbon atoms, a linear or branched alkenyl group having 2 to 18 carbon atoms, a cycloalkyl group having 5 to 12 carbon atoms, and a carbon number of carbon atoms. It represents a phenyl alkyl group of 7 to 15, a phenyl group, or a phenyl group or a phenylalkyl group having 1 to 3 alkyl groups having 1 to 4 carbon atoms as a substituent.
Alternatively, E ² has at least one -OH group, -OCOE ⁵ groups, -OE ⁴ groups, -NCO group, -NH ₂ groups, -NHCOE ⁵ groups, -NHE ⁴ groups or -N (E ^{4) as substituents.} ) Represents an alkyl group having 1 to 24 carbon atoms or an alkenyl group having 2 to 18 carbon atoms having _{two groups or a group combining them.}
Or at least one -O- group, -NH- group, or -NE ⁴ - groups, or are linked by a group composed of a combination of them, and at least one -OH group as a substituted or unsubstituted group, -OE ⁴ group , -NH represents an alkyl group having 1 to 24 carbon atoms or an alkenyl group having 2 to 18 carbon atoms having a group having _{two groups or a combination thereof.}
E ⁴ represents a linear or branched alkyl group having 1 to 24 carbon atoms.
E ⁵ is a hydrogen atom, a linear or branched alkylene group having 1 to 18 carbon atoms, a cycloalkyl group having 5 to 12 carbon atoms, and a linear or branched alkenyl group having 2 to 18 carbon atoms. Represents an aryl group having 6 to 14 carbon atoms or an aralkyl group having 7 to 15 carbon atoms.

E ³ is an alkyl group having 1 to 20 carbon atoms, a hydroxyalkyl group having 2 to 20 carbon atoms, an alkenyl group having 3 to 18 carbon atoms, a cycloalkyl group having 5 to 12 carbon atoms, and a phenylalkyl group having 7 to 15 carbon atoms. A group, an aryl group having 6 to 10 carbon atoms, an aryl group having one or two alkyl groups having 1 to 4 carbon atoms as a substituent, or a 1,1,2,2-tetrahydroperfluoroalkyl group (perfluoro of this group). The alkyl moiety represents 6 to 16 carbon atoms).

Alternatively, in the general formula (2), G ¹ represents a hydrogen atom, G ² represents a chlorine atom, a fluorine atom, -CF ₃ groups, -SOE ³ groups or -SO ₂ E ³ groups, and E ¹ represents a hydrogen atom. Alternatively, it represents a linear or branched alkyl group having 1 to 24 carbon atoms, E ² represents the same group as ^{E 2} defined above, ^{and E 3} represents a linear or branched alkyl group having 1 to 7 carbon atoms. It is a benzotriazole-based compound having a structure represented by a chain-like alkyl group.

The benzotriazole-based compound particularly preferably used in the present invention is a compound having a structure represented by the general formula (III) in which at least one substituent of ^{R 22 to} R ^{25 has an aromatic ring.}

Hereinafter, benzotriazole-based compounds (exemplified compounds 1 to 6) suitable for the present invention will be shown, but the present invention is not limited thereto.

Among the above benzotriazole compounds, the most preferable compound is Exemplified Compound 1.

The compound having a structure represented by the general formula (III) is preferably a compound having a structure represented by the following general formula (V).

In the general formula ^{(V), R 26} is a linear or branched alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 8 carbon atoms, an alkenyl group having 3 to 8 carbon atoms, aryl having 6 to 18 carbon atoms Represents a group, an alkylaryl group having 7 to 18 carbon atoms or an arylalkyl group having 7 to 18 carbon atoms. However, these alkyl groups, cycloalkyl groups, alkenyl groups, aryl groups, alkylaryl groups or arylalkyl groups are hydroxy groups, halogen atoms, alkyl groups having 1 to 12 carbon atoms or 1 to 12 carbon atoms as substituents. It may have an alkoxy group of, or may be linked with an oxygen atom, a sulfur atom, a carbonyl group, an ester group, an amide group or an imino group, and these substituents and linking groups may be used in combination. Good. R ²⁷ represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms or an alkenyl group having 3 to 8 carbon atoms. R ²⁸ represents a hydrogen atom or a hydroxy group, and at least one is a hydroxy group. R ²⁹ represents a hydrogen atom or -OR ²⁶ .

The linear or branched alkyl group having 1 to 12 carbon atoms represented by ^{R 26} in the general formula (V), for example, a methyl group, an ethyl group, a propyl group, an isopropyl group, butyl group, isobutyl group, sec- Butyl group, tert-butyl group, amyl group, isoamyl group, tert-amyl group, hexyl group, heptyl group, n-octyl group, isooctyl group, tert-octyl group, 2-ethylhexyl group, nonyl group, isononyl group, decyl Examples include a group, an undecyl group, and a dodecyl group.

The cycloalkyl group having 3 to 8 carbon atoms represented by R ²⁶ in the general formula (V), for example, cyclopropyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group and the like.

The alkenyl group having 3 to 8 carbon atoms represented by R ²⁶ in the general formula (V), for example, straight-chain or branched propenyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl unsaturated It can be mentioned regardless of the position of the bond.

The aryl group or an alkylaryl group having 7 to 18 carbon atoms having 6 to 18 carbon atoms represented by ^{R 26} in the general formula (V), for example, a phenyl group, a naphthyl group, 2-methylphenyl group, 3-methyl Phenyl group, 4-methylphenyl group, 4-vinylphenyl group, 3-isopropylphenyl group, 4-isopropylphenyl group, 4-butylphenyl group, 4-isobutylphenyl group, 4-tert-butylphenyl group, 4-hexyl Phenyl group, 4-cyclohexylphenyl group, 4-octylphenyl group, 4- (2-ethylhexyl) phenyl group, 2,3-dimethylphenyl group, 2,4-dimethylphenyl group, 2,5-dimethylphenyl group, 2 , 6-Dimethylphenyl group, 3,4-dimethylphenyl group, 3,5-dimethylphenyl group, 2,4-di-tert-butylphenyl group, 2,5-di-tert-butylphenyl group, 2,6 -Di-tert-butylphenyl group, 2,4-di-tert-pentylphenyl group, 2,5-di-tert-amylphenyl group, 2,5-di-tert-octylphenyl group, biphenyl group, 2 , 4,5-trimethylphenyl group and the like.

The aryl alkyl group having 7 to 18 carbon atoms represented by ^{R 26} in the general formula (V), for example, benzyl group, phenethyl group, 2-phenyl-2-yl group, diphenylmethyl group and the like.

Examples of the alkyl group having 1 to 8 carbon atoms represented by ^{R 27} in the general formula (V), for example, a methyl group, an ethyl group, a propyl group, an isopropyl group, butyl group, sec--butyl, tert- butyl group, Examples thereof include an isobutyl group, an amyl group, a tert-amyl group, an octyl group and a tert-octyl group. Among them, a methyl group is preferable because it has an excellent ability to absorb ultraviolet rays.

Examples of the alkenyl group having 3 to 8 carbon atoms represented by R ²⁷ of the general formula (V) include those similar to the alkenyl group having 3 to 8 carbon atoms represented by ^{R 26 of the general formula (V).} ..

Hereinafter, triazine compounds (exemplified compounds 7 to 17) represented by the general formula (V) will be shown, but the present invention is not limited thereto.

In the present invention, the compound having the structure represented by the general formula (III) can be used alone or in combination of two or more.

The molecular weight of the compound having the structure represented by the general formula (III) is preferably in the range of 100 to 3000, more preferably 100 to 800, from the viewpoint of compatibility between the compound and the solvent or polyimide. It is within the range. When it is in the range of 100 to 800, the precipitation of the compound itself and the occurrence of bleed-out can be suppressed, and the compound can be uniformly dispersed in the dope.

The method for adding the compound having the structure represented by the general formula (III) is to dissolve it in an alcohol such as methanol, ethanol or butanol described later, an organic solvent such as dichloromethane, methyl acetate, acetone or dioxolane, or a mixed solvent thereof. It may be added to the dope from or directly into the dope composition. Further, as the organic solvent, one kind of organic solvent may be used alone, or two or more kinds of organic solvents may be mixed and used in an arbitrary ratio.

The amount of the compound having the structure represented by the general formula (III) is not particularly limited as long as the effect of the present invention is exhibited, but from the viewpoint of preventing bleed-out and precipitation, 2 to 20% by mass with respect to polyimide. The range of 3 to 10% by mass is preferable, and the range of 3 to 10% by mass is more preferable.

<Other additives>
(Inorganic filler)
Inorganic fillers can be mixed with the polyimide film of the present invention as long as the effects of the present invention are not impaired.
As the inorganic filler, it is preferable to use inorganic compound particles. Inorganic compound particles include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate, Calcium phosphate and the like can be mentioned. As the inorganic compound particles, those containing silicon are preferable in that the turbidity is low, and silicon dioxide is particularly preferable.

The average particle size of the primary particles of the inorganic compound particles is preferably in the range of 5 to 400 nm, more preferably in the range of 10 to 300 nm. These may be mainly contained as secondary aggregates having a particle size in the range of 0.05 to 0.3 μm, and particles having an average particle size in the range of 80 to 400 nm do not aggregate. It is also preferable that it is contained as a secondary particle.

The content of these particles in the film is preferably in the range of 0.01 to 1% by mass, and particularly preferably in the range of 0.05 to 0.5% by mass.
In the case of a multi-layered film produced by the cocurrent spreading method, it is preferable that the surface contains particles in this amount.

Silicon dioxide particles are commercially available under the trade names of Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, and TT600 (all manufactured by Nippon Aerosil Co., Ltd.) and should be used. Can be done.

Zirconium oxide particles are commercially available under the trade names of Aerosil R976 and R811 (all manufactured by Nippon Aerosil Co., Ltd.) and can be used.

Examples of the resin particles include silicone resin, fluororesin, and acrylic resin. Of these, silicone resins are preferable, and those having a three-dimensional network structure are particularly preferable. For example, Tospearl 103, 105, 108, 120, 145, 3120 and 240 (all manufactured by Toshiba Silicone Co., Ltd.). It is commercially available under the trade name and can be used.

Among these, Aerosil 200V and Aerosil R972V are particularly preferably used because they have a large effect of lowering the friction coefficient while keeping the haze of the film low.

(UV absorber)
It is preferable that the polyimide film of the present invention contains an ultraviolet absorber from the viewpoint of improving light resistance. The ultraviolet absorber aims to improve the light resistance by absorbing ultraviolet rays of 400 nm or less, and in particular, the transmittance at a wavelength of 370 nm is preferably in the range of 0.1 to 30%, which is more preferable. Is in the range of 1 to 20%, more preferably in the range of 2 to 10%.

The ultraviolet absorber preferably used in the present invention is a benzotriazole-based ultraviolet absorber, a benzophenone-based ultraviolet absorber, and a triazine-based ultraviolet absorber, and particularly preferably a benzotriazole-based ultraviolet absorber and a benzophenone-based ultraviolet absorber.

For example, 5-chloro-2- (3,5-di-sec-butyl-2-hydroxylphenyl) -2H-benzotriazole, (2-2H-benzotriazole-2-yl) -6- (linear or side chain). Chain dodecyl) -4-methylphenol, 2-hydroxy-4-benzyloxybenzophenone, 2,4-benzyloxybenzophenone, etc., as well as chinubin 109, chinubin 171, chinubin 234, chinubin 326, chinubin 327, chinubin 328, There are chinubins such as chinubin 928, all of which are commercially available products manufactured by BASF Japan Co., Ltd. and can be preferably used. Of these, halogen-free ones are preferable.

In addition, a disk-shaped compound such as a compound having a 1,3,5-triazine ring is also preferably used as an ultraviolet absorber.

The polyimide film of the present invention preferably contains two or more types of ultraviolet absorbers.

Further, as the ultraviolet absorber, a polymer ultraviolet absorber can also be preferably used, and in particular, the polymer type ultraviolet absorber described in JP-A-6-148430 is preferably used. Moreover, it is preferable that the ultraviolet absorber does not have a halogen group.

The method of adding the ultraviolet absorber is to dissolve the ultraviolet absorber in an alcohol such as methanol, ethanol or butanol, an organic solvent such as dichloromethane, methyl acetate, acetone or dioxolane, or a mixed solvent thereof, and then add the ultraviolet absorber to the dope. It may be added directly into the dope composition.

Those that do not dissolve in an organic solvent, such as inorganic powder, are dispersed in an organic solvent and a polyimide film using a dissolver or sand mill, and then added to the dope.

The amount of the UV absorber used is not uniform depending on the type of UV absorber, usage conditions, etc., but when the dry film thickness of the polyimide film is within the range of 15 to 50 μm, it is 0.5 with respect to the polyimide film. The range of 10% by mass is preferable, and the range of 0.6 to 4% by mass is more preferable.

(Antioxidant)
Antioxidants are also called anti-deterioration agents.
When an electronic device or the like is placed in a high humidity and high temperature state, the polyimide film may deteriorate.
Since the antioxidant has a role of delaying or preventing the decomposition of the polyimide film due to, for example, halogen in the residual solvent in the polyimide film or phosphoric acid of the phosphoric acid-based plasticizer, the polyimide film of the present invention has a role of delaying or preventing decomposition of the polyimide film. It is preferable to contain it in.

As such an antioxidant, a hindered phenol-based compound is preferably used, for example, 2,6-di-t-butyl-p-cresol, pentaerythrityl-tetrax [3- (3,5-di). -T-Butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis [3] -(3,5-di-t-butyl-4-hydroxyphenyl) propionate], 2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-t-butylanilino)- 1,3,5-triazine, 2,2-thio-diethylenebis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], octadecyl-3- (3,5-di-t) -Butyl-4-hydroxyphenyl) propionate, N, N'-hexamethylenebis (3,5-di-t-butyl-4-hydroxy-hydrocinnamamide), 1,3,5-trimethyl-2,4 , 6-Tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, Tris- (3,5-di-t-butyl-4-hydroxybenzyl) -isocyanurate and the like.
In particular, 2,6-di-t-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3 -(3-T-Butyl-5-methyl-4-hydroxyphenyl) propionate] is preferred.
Further, for example, a hydrazine-based metal inactivating agent such as N, N'-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyl] hydrazine or tris (2,4-di-). A phosphorus-based processing stabilizer such as t-butylphenyl) phosphite may be used in combination.

The amount of these compounds added is preferably in the range of 1 to 10000 ppm, more preferably 10 to 1000 ppm in terms of mass ratio with respect to the polyimide film.

(Peeling accelerator)
Many of the additives that reduce the peeling resistance of the polyimide film have a remarkable effect on the surfactant, and the preferable peeling agent is a phosphoric acid ester-based surfactant, a carboxylic acid or a carboxylate-based surfactant. , Sulfonic acid or sulfonate-based surfactants, and sulfate ester-based surfactants are effective. Further, a fluorine-based surfactant in which a part of hydrogen atoms bonded to the hydrocarbon chain of the above-mentioned surfactant is replaced with a fluorine atom is also effective. The release agent is illustrated below.

RZ-1: C ₈ H ₁₇ OP (= O)-(OH) ₂
RZ-2: C ₁₂ H ₂₅ OP (= O)-(OK) ₂
RZ-3: C ₁₂ H ₂₅ OCH ₂ CH ₂ OP (= O)-(OK) ₂
RZ-4: C ₁₅ H ₃₁ (OCH ₂ CH ₂ ) ₅ OP (= O)-(OK) ₂
RZ-5: {C ₁₂ H ₂₅ O (CH ₂ CH ₂ O) ₅ } _2- P (= O) -OH
RZ-6: {C ₁₈ H ₃₅ (OCH ₂ CH ₂ ) ₈ O} _2- P (= O) -ONH ₄
RZ-7: (t-C ₄ H ₉ ) _3- C ₆ H _2- OCH ₂ CH ₂ OP (= O)-(OK) ₂
RZ-8: (iso-C ₉ H _19- C ₆ H _4- O- (CH ₂ CH ₂ O) _5- P (= O)-(OK) (OH)
RZ-9: C ₁₂ H ₂₅ SO ₃ Na
RZ-10: C ₁₂ H ₂₅ OSO ₃ Na
RZ-11: C ₁₇ H ₃₃ COOH
RZ-12: C ₁₇ H ₃₃ COOH · N (CH ₂ CH ₂ OH) ₃
RZ-13: iso-C ₈ H _17- C ₆ H _4- O- (CH ₂ CH ₂ O) _3- (CH ₂ ) ₂ SO ₃ Na
RZ-14: (iso-C ₉ H ₁₉ ) _2- C ₆ H _3- O- (CH ₂ CH ₂ O) _3- (CH ₂ ) ₄ SO ₃ Na
RZ-15: Sodium triisopropylnaphthalene sulphonate RZ-16: Sodium tri-t-butylnaphthalene sulphonate RZ-17: C ₁₇ H ₃₃ CON (CH ₃ ) CH ₂ CH ₂ SO ₃ Na
RZ-18: C ₁₂ H _25- C ₆ H ₄ SO ₃・ NH ₄

The amount of the peeling accelerator added is preferably in the range of 0.05 to 5 parts by mass, more preferably in the range of 0.1 to 2 parts by mass, and 0.1 to 0 with respect to the polyimide (100 parts by mass). Most preferably, it is in the range of 5.5 parts by mass.

The additives contained in the polyimide film of the present invention are not limited to those described above.

<Manufacturing method of polyimide film>
Hereinafter, a specific example of the method for producing the polyimide film of the present invention will be described. The following form is a preferable form, and the present invention is not limited thereto.

The method for producing a polyimide film is a step of dissolving polyimide in a solvent, adding metal oxide particles and a silane coupling agent to prepare a dope (dope preparation step), and casting the dope on a support. A step of forming a film (casting step), a step of evaporating a solvent from the casting film on a support (solvent evaporation step), a step of peeling the casting film from a support (peeling step), and a step of peeling the obtained film. A step of drying (first drying step), a step of stretching the film (stretching step), a step of further drying the stretched film (second drying step), a step of winding the obtained polyimide film (winding step). including.
When polyamic acid is used instead of polyimide, it is preferable to further have a step (heating step) of heat-treating the stretched film to imidize it.

Further, in the method for producing a transparent polyimide film of the present invention, the standard deviation σ of the gray value in an 8-bit gray scale is in the range of 0.50 to 1.10 in a predetermined rectangular area cut out from the projected image of the transparent polyimide film. The ratio of the occupied area of the black portion in the binarized image of the rectangular area is adjusted to 50% or less, and the occurrence of unevenness in the projected image when observed through a point light source is suppressed.
Specific means for achieving this include the following methods (i) to (iii).

(I) The reaction rate of dehydration condensation when the metal oxide particles are connected via the silane coupling agent is controlled.
For example, a silane coupling agent having a slow reaction rate is selected so that the water gradually generated after the film is cured is drained. Since the reaction rate is often accelerated when the pH of the dope comes into contact with the basic side, a silane coupling agent having no such group, for example, a silane coupling agent having no amino group is used. select.

(Ii) Make sure that the water generated before the phase separation between the polyimide and the solvent occurs is drained.
As a means for achieving this, one is to add an additive having aromaticity such as the above-mentioned aromatic compound. Aromatic compounds are highly hydrophobic, so they repel water and allow water to escape quickly.
Another method is to add an azeotropic dehydrating agent that is miscible with water, stop the vaporization of the azeotropic dehydrating agent, and quickly drain the water.

(Iii) Change the order in which the polyimide solution, the metal oxide particles, and the silane coupling agent are added to the solvent.
That is, in order to reduce the influence of water generated by the dehydration condensation of the metal oxide particles and the silane coupling agent as much as possible (reduce the contact time with water), the metal oxide particles and the silane coupling agent are added to the solvent. After a lapse of a predetermined time, the polyimide (solution) is mixed.

Hereinafter, each step of the method for producing a polyimide film according to this embodiment will be described.

(Dope preparation process)
In the dope preparation step, at least polyimide, metal oxide particles, a silane coupling agent and a solvent are mixed to prepare the dope. If necessary, other additives such as aromatic compounds and an azeotropic dehydrating agent (details will be described later) may be mixed. Since the polyimide, metal oxide particles, silane coupling agent and other additives are the same as those described above, description thereof will be omitted here.

The solvent may be any solvent as long as it dissolves polyimide and other additives at the same time and the metal oxide particles are well dispersed. For example, dichloromethane, methyl acetate, ethyl acetate, amyl acetate, acetone, methyl ethyl ketone, tetrahydrofuran, 1 , 3-Dioxolane, 1,4-dioxane, cyclohexanone, ethyl formate, nitroethane, N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-diethylacetamide, N, N-dimethylformamide, N, N -Diethylformamide, N-methylcaprolactam, hexamethylphosphoramide, tetramethylenesulfone, dimethyl sulfoxide, m-cresol, phenol, p-chlorophenol, 2-chloro-4-hydroxytoluene, diglime, triglime, tetraglime, dioxane , Γ-Butyrolactone, dioxolane, cyclopentanone, epsilon caprolactam, chloroform and the like.
In addition to these solvents, a poor solvent such as hexane, heptane, benzene, toluene, xylene, chlorobenzene, or o-dichlorobenzene may be used to the extent that the polyimide and additives according to the present invention do not precipitate.

Alcohol-based solvents can also be used, for example, 2,2,2-trifluoroethanol, 2,2,3,3-hexafluoro-1-propanol, 1,3-difluoro-2-propanol, 1, 1,1,3,3,3-hexafluoro-2-methyl-2-propanol, 1,1,1,3,3,3-hexafluoro-2-propanol, 2,2,3,3-3 Examples thereof include pentafluoro-1-propanol, nitroethane, methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol, tert-butanol and the like. Among them, it is preferable to select from methanol, ethanol and butanol from the viewpoint of improving the peelability and enabling high-speed casting, and it is more preferable to use methanol or ethanol. Higher proportions of alcohol in the dope gels the web, facilitating delamination from the metal support.

These solvents may be used alone or in combination of two or more.

In order to azeotropically dehydrate the water generated when the metal oxide particles and the silane coupling agent are dehydrated and condensed in the film drying step, the azeotropic dehydrating agent may be added in advance in the dope adjustment step.
As the co-boiling dehydrating agent, for example, aromatic hydrocarbons such as toluene, xylene and solvent naphtha, alicyclic hydrocarbons such as cyclohexane, methylcyclohexane and dimethylcyclohexane can be used.
When an azeotropic dehydrating agent is used, the amount added is about 1 to 30% by mass based on the total amount of the organic solvent.

For dissolution of polyimide and other additives (when added), a method performed at normal pressure, a method performed below the boiling point of the main solvent, a method performed by pressurizing above the boiling point of the main solvent, JP-A-9-95544. Various melting methods are used, such as the method performed by the cooling dissolution method described in JP-A, JP-A-9-95557 or JP-A-9-95538, and the method performed at high pressure described in JP-A-11-21379. be able to.

The prepared dope may be guided to a filter by a liquid feed pump or the like and filtered. As the filter medium used for filtration, a metal firing filter, a metal non-woven fabric filter, a cotton cloth filter, a paper filter and the like can be appropriately used. Further, the dope and the metal oxide particles may be filtered separately before the addition, or may be filtered after the addition. Regarding the temperature at the time of filtration, for example, when the main solvent of the dope is dichloromethane, the gel-like foreign matter in the dope is removed by filtering the dope at a temperature of + 5 ° C. or higher at 1 atm of the dichloromethane. Can be done. The preferred temperature range is 45 to 120 ° C, more preferably 45 to 70 ° C, and even more preferably 45 to 55 ° C.

Further, in many cases, the main dope may contain a return material in the range of 10 to 50% by mass. The return material is a part that is reused as a raw material for some reason. For example, it is a finely crushed polyimide film, and both side parts of the film that are generated when the polyimide film is formed are cut off. Polyimide film raw material that exceeds the specified value of the film due to objects or scratches is used.
Further, as the raw material of the resin used for the dope preparation, a resin obtained by pelletizing polyimide or other compounds in advance can also be used.

(Collecting film forming process)
In the casting film forming step, the dope (main dope) prepared in the dope preparation step is cast on the support to form a casting film. For example, the flow position on a metal support such as a stainless belt, a rotating metal drum, etc., which feeds the dope to a die through a liquid feed pump (for example, a pressurized metering gear pump) and transfers it indefinitely. (For example, an endless belt casting device) is cast with a dope from a die.
The metal support in casting is preferably a mirror-finished surface, and the support includes a stainless steel belt, a drum whose surface is plated with a casting, a stainless belt, a stainless steel belt, or the like. It is preferably used. The width of the cast can be in the range of 1 to 4 m, preferably in the range of 1.5 to 3 m, more preferably in the range of 2 to 2.8 m.

The support does not have to be made of metal, for example, polyethylene terephthalate (PET) film, polyethylene naphthalate (PEN) film, polybutylene terephthalate (PBT) film, nylon 6 film, nylon 6,6 film, polypropylene film. , A belt such as polytetrafluoroethylene can be used. When polyimide is used as the flexible substrate, the polyimide may be wound together with the metal support in which the polyimide is cast.

The traveling speed of the metal support is not particularly limited, but is usually 5 m / min or more, preferably in the range of 10 to 180 m / min, and particularly preferably in the range of 80 to 150 m / min. As the traveling speed of the metal support is higher, the accompanying gas is more likely to be generated, and the occurrence of film thickness unevenness due to disturbance becomes remarkable. The traveling speed of the metal support is the moving speed of the outer surface of the metal support.

The surface temperature of the metal support is preferably higher because the drying rate of the casting film can be increased, but if it is too high, the casting film may foam or the flatness may deteriorate. It is preferably carried out within a temperature range of −50 to −10 ° C. with respect to the boiling point of the solvent.

The die has a shape that gradually becomes thinner toward the discharge port in a cross section perpendicular to the width direction. Specifically, the die usually has tapered surfaces on the downstream side and the upstream side in the traveling direction of the lower portion, and a discharge port is formed in a slit shape between the tapered surfaces. A metal die is preferably used, and specific examples thereof include stainless steel and titanium. In the present invention, when producing films having different thicknesses, it is not necessary to change to dies having different slit gaps.
It is preferable to use a pressure die that can adjust the slit shape of the die base portion and can easily make the film thickness uniform. The pressure die includes a coat hanger die, a T die, and the like, and any of them is preferably used. Even when films of different thickness are continuously produced, the discharge rate of the die is maintained at a substantially constant value. Therefore, when a pressure die is used, conditions such as extrusion pressure and shear rate are also omitted. It is maintained at a constant value. Further, in order to increase the film forming speed, two or more pressure dies may be provided on the metal support, and the doping amount may be divided and laminated.

(Solvent evaporation step)
In the solvent evaporation step, the solvent is evaporated from the casting film on the support. That is, this step is a pre-drying step performed on the metal support, heating the cast film on the metal support and evaporating the solvent.
To evaporate the solvent, for example, a method of blowing heating air from the casting film side and the back side of the metal support with a dryer, a method of transferring heat from the back surface of the metal support with a heating liquid, and a method of transferring heat from the front and back by radiant heat. And so on. A method of appropriately selecting and combining them is also preferable. The surface temperature of the metal support may be the same as a whole or may differ depending on the position. The temperature of the heating air is preferably in the range of 10 to 220 ° C.

In the solvent evaporation step, it is preferable to dry the casting film until the residual solvent amount is in the range of 10 to 150% by mass from the viewpoint of the peelability of the casting film and the transportability after peeling. In the present invention, the amount of residual solvent is represented by the following mathematical formula (3).

Formula (3)
Residual solvent amount (mass%) = {(MN) / N} x 100

In the above mathematical formula (3), M is the mass of the casting film (film) at a predetermined time point. N is the mass of M at 200 ° C. for 3 hours. In particular, M when calculating the amount of residual solvent achieved in the solvent evaporation step is the mass of the cast film immediately before the peeling step.

(Peeling process)
In the peeling step, the cast film in which the solvent is evaporated on the metal support in the solvent evaporation step is peeled from the support at the peeling position.
The peeling tension when peeling the metal support and the casting film is usually in the range of 60 to 400 N / m, but if wrinkles are likely to occur during peeling, the metal support is peeled at a tension of 190 N / m or less. Is preferable.
The temperature at the peeling position on the metal support is preferably in the range of -50 to 60 ° C, more preferably in the range of 10 to 40 ° C, and preferably in the range of 15 to 40 ° C. Most preferred.
The peeled film may be sent directly to the stretching step, or may be sent to the stretching step after being sent to the first drying step so as to achieve a desired residual solvent amount. In the present invention, from the viewpoint of stable transport in the stretching step, it is preferable that the film is sequentially fed to the first drying step and the stretching step after the peeling step.

(1st drying step)
The first drying step is a drying step of heating the film and further evaporating the solvent. The drying means is not particularly limited, and for example, hot air, infrared rays, a heating roller, microwaves, or the like can be used. From the viewpoint of convenience, it is preferable to dry the film with hot air or the like while transporting the film with rollers arranged in a staggered pattern. The drying temperature is preferably in the range of 30 to 200 ° C. in consideration of the amount of residual solvent, the expansion / contraction rate during transportation, and the like.

(Stretching process)
In the stretching step, the film is stretched. By stretching the film peeled from the metal support in this way, the film thickness, flatness, orientation, etc. of the film can be controlled.
In the manufacturing method according to this embodiment, the film is stretched in the longitudinal direction and / or the lateral direction. The stretching operation may be performed in multiple stages. Further, when biaxial stretching is performed, simultaneous biaxial stretching may be performed, or biaxial stretching may be performed step by step. In this case, the term “stepwise” means, for example, that stretching in different stretching directions can be sequentially performed, stretching in the same direction is divided into multiple stages, and stretching in different directions is added to any of the steps. Is also possible.

That is, for example, the following stretching step is also possible.
・ Stretching in the longitudinal direction → Stretching in the width direction → Stretching in the longitudinal direction → Stretching in the longitudinal direction ・ Stretching in the width direction → Stretching in the width direction → Stretching in the longitudinal direction → Stretching in the longitudinal direction

Further, the simultaneous biaxial stretching includes a case where the drawing is performed in one direction and the other is contracted by relaxing the tension.

The amount of residual solvent at the start of stretching is preferably in the range of 0.1 to 200% by mass. When the amount of the residual solvent is in the above range, the effect of improving the flatness by stretching can be obtained, and sufficient film strength can be obtained.

In the production method according to the present embodiment, the film may be stretched in the longitudinal direction and / or the width direction, preferably in the width direction, so that the film thickness after stretching is within a desired range. It is preferable to stretch the film in a temperature range of (Tg-200) to (Tg + 100) ° C. with respect to the glass transition temperature (Tg) of the film. When stretched in the above temperature range, the stretching stress can be reduced and the haze becomes low. Further, it is possible to obtain a polyimide film which suppresses the occurrence of breakage and has excellent flatness and colorability of the film itself. The stretching temperature is more preferably carried out in the temperature range of (Tg-150) to (Tg + 50) ° C. In addition, this step may be performed (simultaneously) in the same step as the first drying step.

In the manufacturing method according to the present embodiment, the self-supporting film peeled from the support can be stretched in the longitudinal direction by regulating the traveling speed with a stretching roller.
In order to stretch in the width direction, for example, the width of both ends of the width of the film is held by a clip or a pin in the width direction by performing a total drying treatment or a part of the treatment as shown in JP-A-62-46625. A method of drying while drying (called a tenter method), in particular, a tenter method using a clip is preferably used. It is preferable that the film stretched in the longitudinal direction or the unstretched film is introduced into the tenter with both ends in the width direction gripped by the clip, and is stretched in the width direction while traveling together with the clip-type tenter.

When stretching in the width direction, it is preferable to stretch the film at a stretching speed in the range of 50 to 1000% / min in the width direction from the viewpoint of improving the flatness of the film. When the stretching speed is 50% / min or more, the flatness is improved and the film can be processed at high speed, which is preferable from the viewpoint of production suitability. When the stretching speed is 1000% / min or less, the film breaks. It is preferable because it can be processed without any problem. A more preferred stretching rate is in the range of 100-500% / min. The stretching speed is defined by the following mathematical formula (4).

Formula (4)
Stretching rate (% / min) = {(d ₁ / d ₂ ) -1} x 100 (%) / t

In the above mathematical formula (4), d ₁ is the width dimension of the film after stretching in the stretching direction. d ₂ is the width dimension in the stretching direction of the film before stretching. t is the time (min) required for stretching.

In the stretching step, holding / relaxation is usually performed after stretching. That is, in this step, it is preferable to perform a stretching step of stretching the film, a holding step of holding the film in a stretched state, and a relaxing step of relaxing the film in the stretching direction in these orders. In the holding step, stretching at the stretching ratio achieved in the stretching step is held at the stretching temperature in the stretching step. In the relaxation step, the stretching in the stretching step is held in the holding step, and then the tension for stretching is released to relax the stretching. The relaxation step may be performed at a temperature equal to or lower than the stretching temperature in the stretching step.

(Second drying step)
In the second drying step, the stretched film is further heated and dried. When the film is heated by hot air or the like, a means for preventing the mixing of used hot air by installing a nozzle capable of exhausting used hot air (air containing a solvent or wet air) is also preferably used. The hot air temperature is preferably in the range of 40 to 350 ° C. The drying time is preferably about 5 seconds to 30 minutes, more preferably 10 seconds to 15 minutes.

Further, the heating and drying means is not limited to hot air, and for example, infrared rays, heating rollers, microwaves, and the like can be used. From the viewpoint of convenience, it is preferable to dry the film with hot air or the like while transporting the film with rollers arranged in a staggered pattern. The drying temperature is preferably in the range of 40 to 350 ° C. in consideration of the amount of residual solvent, the expansion / contraction rate during transportation, and the like.

In the second drying step, it is preferable to dry the film until the residual solvent amount becomes 0.5% by mass or less.

(Winding process)
In the winding step, the film obtained above is wound. Preferably, in the winding step, the obtained film is wound and then cooled to room temperature. The winder may be a generally used one, and can be wound by a winding method such as a constant tension method, a constant torque method, a taper tension method, or a program tension control method with a constant internal stress.

Here, the thickness of the obtained film is not particularly limited, and is preferably in the range of 1 to 200 μm, particularly preferably in the range of 10 to 100 μm.

In the winding step, both ends of the film sandwiched by a clip-type tenter (tenter clip) or the like when stretched and conveyed may be slit. It is preferable that the slit end of the film is finely cut within a width of 1 to 30 mm, then dissolved in a solvent and reused as a return material.
The ratio of the portion of the molded film that is reused as the return material is preferably in the range of 10 to 90% by mass, more preferably 20 to 80% by mass, and further preferably 30 to 70% by mass.
The input amount varies slightly depending on the amount of the return material generated during or finally in the film forming process, but usually, the mixing ratio of the return material with respect to the total solid content in the dope is about 10 to 50% by mass, preferably 15. It is about 40% by mass. It is preferable that the mixing ratio of the return material is as constant as possible from the viewpoint of production stability.

Each step from the solvent evaporation step to the winding step described above may be carried out in an air atmosphere or an inert gas atmosphere such as nitrogen gas. Further, it is preferable that each step, particularly the drying step and the stretching step, is performed in consideration of the explosive limit concentration of the solvent in the atmosphere.

(Heating process)
As described above, when polyamic acid is used instead of polyimide, it is preferable to heat-treat the stretched film to imidize it. Specifically, after the winding step, the film dried in the second drying step is further heat-treated in order to promote imidization within the polymer chain molecule and between the polymer chain molecules to improve the mechanical properties. Perform the process.
Further, even when the dope is prepared using polyimide (imidization rate 100%) or the film imidization rate becomes 100% by performing the second drying step, the residual stress of the film is obtained. A heating process is performed for the purpose of alleviating the problem. The second drying step may also serve as a heating step.

The heating means is performed by using known means such as hot air, an electric heater, and a microwave. As the electric heater, the infrared heater described above can be used.
The heat treatment conditions are preferably carried out within a temperature range of 200 to 450 ° C. and within a range of 30 seconds to 1 hour. Thereby, the dimensional stability of the polyimide film can be improved. In the heating step, if the film is rapidly heated, problems such as an increase in surface defects occur. Therefore, it is preferable to appropriately select the heating method. Further, the heating step is preferably performed in a low oxygen atmosphere.
If the heating temperature in the second drying step and the heating step exceeds 450 ° C., the energy required for heating becomes very large, so that the manufacturing cost increases and the environmental load further increases. Therefore, the heating temperature is 450 ° C. It is preferable to make the following.
After the winding step, before or after the heating step, a step of slitting the widthwise end portion of the polyimide film, a step of removing static electricity from the polyimide film when it is charged, and the like are further performed. May be.

<< Organic EL display >>
The transparent polyimide film of the present invention can be used as a front plate of various flexible displays, and examples thereof include an organic electroluminescence display (organic EL display).
By providing the transparent polyimide film of the present invention in the organic EL display of the present invention, unevenness of the film when viewed through polarized sunglasses is not noticeable, and visibility can be improved.

Regarding the outline of the organic EL element applicable to the organic EL display of the present invention, for example, Japanese Patent Application Laid-Open No. 2013-157634, Japanese Patent Application Laid-Open No. 2013-168552, Japanese Patent Application Laid-Open No. 2013-177361, Japanese Patent Application Laid-Open No. 2013-187211 Japanese Patent Application Laid-Open No. 2013-191644, Japanese Patent Application Laid-Open No. 2013-191804, Japanese Patent Application Laid-Open No. 2013-225678, Japanese Patent Application Laid-Open No. 2013-235994, Japanese Patent Application Laid-Open No. 2013-243234, Japanese Patent Application Laid-Open No. 2013-243236, JP-A-2013-242366, JP-A-2013-243371, JP-A-2013-245179, JP-A-2014-003249, JP-A-2014-003299, JP-A-2014-013910, JP-A-2014. Examples thereof include configurations described in Japanese Patent Application Laid-Open No. 2014-017493, Japanese Patent Application Laid-Open No. 2014-017494, and the like.

Further, the polyimide film of the present invention may further have various known functional layers applicable to the front plate when used as the front plate of a flexible display. Examples of the functional layer include layers having functions such as ultraviolet absorption, surface hardness, adhesiveness, hue adjustment, and refractive index adjustment.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited thereto.

[Example 1]
<< Preparation of polyimide solution >>
Polyimide solutions A to C were prepared as follows.

<Preparation of polyimide solution A>
2,2-Bis (3,4-dicarboxyphenyl) -1,1,1, in a four-necked flask equipped with a dry nitrogen gas introduction tube, a cooler, a Dean-Stark aggregator filled with toluene, and a stirrer. Add 25.59 g (57.6 mmol) of 3,3,3-hexafluoropropane dianhydride (acid anhydride A) (manufactured by Daikin Industries, Ltd.) to N, N-dimethylacetamide (DMAc) (134 g), and add a nitrogen stream. Below, it was stirred at room temperature.

To this, 19.2 g (60 mmol) of 4,4'-diamino-2,2'-bis (trifluoromethyl) biphenyl (diamine A) (manufactured by Daikin Industries, Ltd.) was added, and the mixture was heated and stirred at 80 ° C. for 6 hours. Then, the outside temperature was heated to 190 ° C., and the water generated by imidization was azeotropically distilled off together with toluene. After continuing heating, refluxing and stirring for 6 hours, no water was generated. Subsequently, the mixture was heated for 7 hours while distilling off toluene, and after distilling off toluene, methanol was added to reprecipitate, and after drying the solid content, a 20% by mass N, N-dimethylacetamide solution was prepared to prepare a polyimide solution A. ..

<Preparation of polyimide solution B>
3,3', 4,4'-diphenyl ether tetracarboxylic dianhydride (acid anhydride) in a four-necked flask equipped with a dry nitrogen gas introduction tube, a cooler, a Dean-Stark aggregator filled with toluene, and a stirrer. B) 17.87 g (57.6 mmol) (manufactured by Daikin Industries, Ltd.) was added to N, N-dimethylacetamide (134 g), and the mixture was stirred at room temperature under a nitrogen stream.

To this, 11.5 g (60 mmol) of 2,5-diethyl-4,6-dimethylbenzene-1,3-diamine (diamine B) (manufactured by Daikin Industries, Ltd.) was added, and the mixture was heated and stirred at 80 ° C. for 6 hours. Then, the outside temperature was heated to 190 ° C., and the water generated by imidization was azeotropically distilled off together with toluene. After continuing heating, refluxing and stirring for 6 hours, no water was generated. Subsequently, the mixture was heated for 7 hours while distilling off toluene, and after distilling off toluene, methanol was added to reprecipitate, and after drying the solid content, a 20% by mass N, N-dimethylacetamide solution was prepared to prepare a polyimide solution B. ..

<Preparation of polyimide solution C>
A four-necked flask equipped with a dry nitrogen gas introduction tube, a cooler, a Dean-Stark aggregator filled with toluene, and a stirrer was placed in a bicyclo [2.2.2] octa-7-en-2,3,5,6. -Tetracarboxylic acid 2,3: 5,6-dianoxide (acid anhydride C) (manufactured by Daikin Industries, Ltd.) 14.30 g (57.6 mmol) was added to N, N-dimethylacetamide (134 g), and a nitrogen stream was added. Below, it was stirred at room temperature.

To this, 12.3 g (30 mmol) of 4,4'-[isopropyridenebis [(4,1-phenylene) oxy]] bisaniline (diamine C) (manufactured by Daikin Industries, Ltd.) and 4,4'-[(4,1-phenylene) 4'-Biphenylylene) bisoxy] bisaniline (diamine D) (manufactured by Daikin Industries, Ltd.) 11.1 g (30 mmol) was added, and the mixture was heated and stirred at 80 ° C. for 6 hours. Then, the outside temperature was heated to 190 ° C., and the water generated by imidization was azeotropically distilled off together with toluene. After continuing heating, refluxing and stirring for 6 hours, no water was generated. Subsequently, the mixture was heated for 7 hours while distilling off toluene, and after distilling off toluene, methanol was added to reprecipitate, and after drying the solid content, a 20% by mass N, N-dimethylacetamide solution was prepared to prepare a polyimide solution C. ..

<< Preparation of metal oxide particle dispersion liquid >>
Metal oxide particle dispersions A to C were prepared as follows.

<Preparation of metal oxide particle dispersion liquid A>
100 g of an acidic aqueous solution (spherical, particle size 20 nm) of 20% by mass of silica sol gel, 80 g of isopropanol, and 80 g of N, N-dimethylacetamide are placed in a 500 ml reaction flask and heated to 25 to 40 ° C. to distill water and isopropanol. did. This was dried under reduced pressure to obtain a metal oxide particle dispersion A which is an N, N-dimethylacetamide dispersion of 20% by mass silica particles.

<Preparation of metal oxide particle dispersion liquids B and C>
In the preparation of the metal oxide particle dispersion liquid A, the metal oxide particle dispersion liquid B and the metal oxide particle dispersion liquid B and the metal oxide particle dispersion liquid B and C was prepared.

《Preparation of doping》
Dope 101-119 was prepared as follows.

<Preparation of dope 101>
The polyimide solution A, the metal oxide particle dispersion A, the silane coupling agent A below, and the N, N-dimethylacetamide solution of the aromatic compound A below were mixed and stirred for 30 minutes to prepare a dope 101.

The amount of the metal oxide particles (silica particles) and the aromatic compound A added was 20% by mass and 3% by mass, respectively, with respect to the total solid content (100% by mass) in the dope.
The amount of the silane coupling agent A added was 1.67 parts by mass with respect to the total of the metal oxide particles (silica particles) and the polyimide (100 parts by mass).

<Preparation of Dope 102-119>
In the preparation of the dope 101, the polyimide solution, the metal oxide particle dispersion liquid and its addition amount, the aromatic compound and its addition amount, and the solvent were changed as shown in Table I, but the dope 102 to 102 to 119 was prepared.

<< Production of polyimide film >>
The obtained dope 101-119 was applied with a coater on a smooth glass plate on which a very small amount of a release agent was sprayed, and then heated on a hot plate at 160 ° C. for 30 minutes to prepare a self-supporting film. did. After fixing the film peeled off from the glass plate to a stainless steel mold with clips at several points, the organic solvent was almost completely removed (less than 1% by mass) by placing it in a vacuum dryer at 200 ° C. for 2 hours, and the polyimide film. 101-119 were obtained.

《Evaluation》
With respect to the produced polyimide films 101 to 119, the standard deviation σ of the gray value, the occupied area ratio of the black portion in the binarized image, the scratch resistance, and the distortion of the image were evaluated as follows.
The evaluation results are shown in Table I.

<Standard deviation σ of gray value and occupied area ratio of black part in binarized image>
According to the analysis method of the projected image of the film shown in FIG. 1, the standard deviation σ of the gray value and the occupied area ratio of the black portion in the binarized image were calculated.
Specifically, the distance between the film sample 1 (polyimide film 101 to 119) and the white light source 2 (S-light manufactured by Japan Technology Center Co., Ltd.) is adjusted to 60 cm, and the white light source 2 is oblique to the film sample 1. Light was irradiated from the 45 ° direction. The distance between the film sample 1 and the projection surface 3 arranged parallel to the film sample 1 was adjusted to 70 cm, and the shadow of the film sample 1 was projected onto the projection surface 3.
A camera 4 (Canon EOS KISS 50, lens EF-S 18 = 55 mm, ISO sensitivity 100, aperture 5.6, shutter speed 1 /) arranged in a direction of 90 ° from the projection surface 3 at a distance of 80 cm. A photograph was taken with a white balance manual setting for 10 seconds) to obtain a photographed image.

Next, for the obtained projected image, the standard deviation σ of the gray value and the occupied area ratio K (%) of the black portion in the binarized image were calculated according to the following procedures 1 to 7.

1. 1. The captured image was read into a personal computer using the free software ImageJ.
2. A rectangular evaluation area of 1 cm × 5 cm was set in the actual photographed image. At this time, the long side of the rectangle was set to be the transport direction of the film sample.
3. 3. 8-bit grayscale was performed by free software ImageJ.
4. Background correction was performed by the free software ImageJ.
5. The standard deviation σ and the average value m of the gray value (pixel value) in the gray scale were calculated.
6. The rectangular evaluation area was binarized with the average value m as the threshold value.
7.2 The area of the black part (dark part) obtained by digitization was divided by the total area to calculate the occupied area ratio K (%) of the black part.

Here, the free software ImageJ is ImageJ1.32S created by WayneRasband.

<Evaluation of scratch resistance>
The surface scratch resistance of the produced polyimide films 101 to 119 was evaluated by a steel wool scratch resistance test. Specifically, using a Gakushin type abrasion resistance tester (manufactured by Tester Sangyo Co., Ltd.), # 0000 steel wool with a load of 200 g is reciprocated 10 times on the film, and the scratched state on the surface of the film is visually observed. And evaluated according to the following evaluation criteria.

◯: 0 to 5 scratches ×: 6 or more scratches

<Evaluation of image distortion>
Using the produced polyimide films 101 to 119, organic EL display devices 101 to 119 were produced, respectively, and the image distortion was visually evaluated.

Specifically, the above-mentioned polyimide films 101 to 119 are used as a transparent substrate, and a reflective electrode made of chromium is formed on the polyimide film, and a metal electrode is formed on the reflective electrode by using ITO (tin-doped indium oxide) as a metal electrode (anode). did.
As an organic functional layer, poly (3,4-ethylenedioxythiophene) -polystyrene sulfonate (PEDOT: PSS) as a hole transport layer was formed on the anode by a sputtering method to a thickness of 80 nm, and then on the hole transport layer. The light emitting layers R, G, and B of RGB were formed with a layer thickness of 100 nm by using a shadow mask. The red light emitting layer R includes tris (8-hydroxyquinolinate) aluminum (Alq ₃ ) as a host compound and [4-dicyanomethylene-2-methyl-6 (4-dimethylaminostyryl) -4H as a light emitting compound. -Pyran] (DCM) was co-deposited (mass ratio 99: 1) to form a thickness of 100 nm. As the green light emitting layer G, Alq ₃ as a host compound and coumarin 6 (3- (2-benzothiazolyl) -7- (diethylamino) coumarin) as a luminescent compound are co-deposited (mass ratio 99: 1) to 100 nm. Formed with the thickness of. The blue light emitting layer B was formed to have a thickness of 100 nm by co-depositing BAlq as a host compound and perylene as a light emitting compound (mass ratio 90:10).

Further, as a first cathode having a low work function so that electrons can be efficiently injected into the organic functional layer, calcium is deposited to a thickness of 4 nm by a vacuum deposition method, and as a second cathode on the first cathode. Aluminum was formed to a thickness of 2 nm. Here, the aluminum used as the second cathode has a role of preventing the calcium, which is the first cathode, from causing chemical alteration when a transparent conductive film is formed on the transparent conductive film by a sputtering method. Next, a transparent conductive film having a thickness of 80 nm was formed on the cathode by a sputtering method to obtain a transparent electrode. Here, ITO was used as the transparent conductive film. Further, a silicon nitride film of 200 nm was formed on the transparent electrode by the CVD method to form an insulating layer, and a 20 cm × 20 cm organic EL element unit was produced.

Next, as a gas barrier film, a polyethylene terephthalate film with a gas barrier layer having a thickness of 20 μm was used, and a thermosetting liquid adhesive (epoxy resin) was applied to one side of the gas barrier film to a thickness of 25 μm. A sealing unit was produced.

Next, under the reduced pressure conditions of 90 ° C. and 0.1 MPa, the organic EL element unit formed from the transparent substrate to the insulating layer and the sealing unit were laminated and held under pressure for 5 minutes. Subsequently, the laminate was returned to the atmospheric pressure environment and further heated at 90 ° C. for 30 minutes to cure the adhesive, thereby producing organic EL display devices 101 to 119.

Each of the produced organic EL display devices was visually observed from an angle of 45 ° and evaluated according to the following evaluation criteria.

◯: Level at which image distortion is not an issue ×: Level at which image distortion is anxious

<Summary>
As is clear from Table I, it can be seen that the polyimide film of the present invention is superior to the polyimide film of the comparative example in terms of scratch resistance and image distortion.
From the above, the metal oxide particles, the silane coupling agent, and the polyimide are contained, and the metal oxide particles have an average primary particle size in the range of 10 to 100 nm and a content in the transparent polyimide film. It is in the range of 20 to 70% by mass with respect to the total solid content (100% by mass), and when the projected image of the transparent polyimide film is evaluated, the standard deviation σ of the gray value on the 8-bit gray scale is 0.50 to 1. A transparent polyimide film for the front plate of a flexible display that suppresses image distortion and has excellent scratch resistance because the occupied area ratio of the black part in the binarized image is adjusted to 50% or less within the range of 10. It was confirmed that it is useful for providing.

[Example 2]
《Preparation of doping》
Dopes 2001-211 were prepared as follows.

<Preparation of dope 201>
Dope 201 was prepared by mixing a polyimide solution A, a metal oxide particle dispersion liquid A, and an N, N-dimethylacetamide solution of a silane coupling agent A, and stirring for 30 minutes.

The amount of the metal oxide particles (silica particles) added was 50% by mass with respect to the total solid content (100% by mass) in the dope.
The amount of the silane coupling agent A added was 1.67 parts by mass with respect to the total of the metal oxide particles (silica particles) and the polyimide (100 parts by mass).

<Preparation of Dope 202-211>
In the preparation of the dope 201, the dope 202 to 211 were prepared in the same manner except that the polyimide solution, the amount of the metal oxide particles added, and the silane coupling agent were changed as shown in Table II. KR-511 manufactured by Shin-Etsu Silicone Co., Ltd. was used as the silane coupling agent B, KBM-5103 manufactured by Shin-Etsu Silicone Co., Ltd. was used as the silane coupling agent E, and KBM-502 manufactured by Shin-Etsu Silicone Co., Ltd. was used as the silane coupling agent F.

<< Production of polyimide film >>
The obtained dope 201 to 211 is applied with a coater on a smooth glass plate on which a very small amount of a release agent is sprayed, and then heated on a hot plate at 160 ° C. for 30 minutes to prepare a self-supporting film. did. After fixing the film peeled off from the glass plate to a stainless steel mold with clips at several points, the organic solvent was almost completely removed (less than 1% by mass) by placing it in a vacuum dryer at 200 ° C. for 2 hours, and the polyimide film. 2001-211 were obtained.

《Evaluation》
With respect to the produced polyimide films 2001 to 211, the standard deviation σ of the gray value, the occupied area ratio of the black portion in the binarized image, the scratch resistance, and the distortion of the image were evaluated in the same manner as in Example 1.
The evaluation results are shown in Table II.

<Summary>
As is clear from Table II, the polyimide film of the present invention is superior to the polyimide film of the comparative example in terms of scratch resistance and image distortion.
From the above, the metal oxide particles, the silane coupling agent, and the polyimide are contained, and the metal oxide particles have an average primary particle size in the range of 10 to 100 nm and a content in the transparent polyimide film. It is in the range of 20 to 70% by mass with respect to the total solid content (100% by mass), and when the projected image of the transparent polyimide film is evaluated, the standard deviation σ of the gray value on the 8-bit gray scale is 0.50 to 1. A transparent polyimide film for the front plate of a flexible display that suppresses image distortion and has excellent scratch resistance because the occupied area ratio of the black part in the binarized image is adjusted to 50% or less within the range of 10. It was confirmed that it is useful for providing.

[Example 3]
《Preparation of doping》
Dopes 301-309 were prepared as follows.

<Preparation of dope 301>
The polyimide solution A, the metal oxide particle dispersion liquid A, and the silane coupling agent A were mixed and stirred for 30 minutes to prepare a dope 301.

The amount of the metal oxide particles (silica particles) added was 50% by mass with respect to the total solid content (100% by mass) in the dope.
The amount of the silane coupling agent A added was 1.67 parts by mass with respect to the total of the metal oxide particles (silica particles) and the polyimide (100 parts by mass).

<Preparation of dope 302>
Dope 302 was prepared by mixing polyimide solution A, metal oxide particle dispersion liquid A, silane coupling agent A, and toluene as an azeotropic dehydrating agent, and stirring for 30 minutes.

The amount of the metal oxide particles (silica particles) added was 50% by mass with respect to the total solid content (100% by mass) in the dope.
The amount of the silane coupling agent A added was 1.67 parts by mass with respect to the total of the metal oxide particles (silica particles) and the polyimide (100 parts by mass).
The azeotropic dehydrating agent was mixed at a ratio of 1.00 parts by mass with respect to 100 parts by mass of N, N-dimethylacetamide as the main solvent.

<Preparation of Dope 303-309>
In the preparation of the dope 302, the dope 302 to 309 were prepared in the same manner except that the addition amount of the polyimide solution and the metal oxide particle dispersion and the azeotropic dehydrating agent were changed as shown in Table III.

<< Production of polyimide film >>
The obtained dope 301 to 309 was applied with a coater on a smooth glass plate on which a very small amount of a release agent was sprayed, and then heated on a hot plate at 160 ° C. for 30 minutes to prepare a self-supporting film. did. After fixing the film peeled off from the glass plate to a stainless steel mold with clips at several points, the organic solvent was almost completely removed (less than 1% by mass) by placing it in a vacuum dryer at 200 ° C. for 2 hours, and the polyimide film. 301-309 were obtained.

《Evaluation》
With respect to the produced polyimide films 301 to 309, the standard deviation σ of the gray value, the occupied area ratio of the black portion in the binarized image, the scratch resistance, and the distortion of the image were evaluated in the same manner as in Example 1.
The evaluation results are shown in Table III.

<Summary>
As is clear from Table III, it can be seen that the polyimide film of the present invention is superior to the polyimide film of the comparative example in terms of scratch resistance and image distortion.
From the above, the metal oxide particles, the silane coupling agent, and the polyimide are contained, and the metal oxide particles have an average primary particle size in the range of 10 to 100 nm and a content in the transparent polyimide film. It is in the range of 20 to 70% by mass with respect to the total solid content (100% by mass), and when the projected image of the transparent polyimide film is evaluated, the standard deviation σ of the gray value on the 8-bit gray scale is 0.50 to 1. A transparent polyimide film for the front plate of a flexible display that suppresses image distortion and has excellent scratch resistance because the occupied area ratio of the black part in the binarized image is adjusted to 50% or less within the range of 10. It was confirmed that it is useful for providing.

1 Film sample (polyimide film)
2 White light source 3 Projection surface 4 Camera

Claims (8)

A transparent polyimide film for a flexible display front plate containing metal oxide particles, a silane coupling agent, and polyimide.
The polyimide is one of a polyimide obtained by polymerizing the following acid anhydride B and the following diamine B, and a polyimide obtained by polymerizing the following acid anhydride C, the following diamine C and the following diamine D.
The metal oxide particles have an average primary particle size in the range of 10 to 100 nm, and the content is 20 to 70% by mass with respect to the total solid content (100% by mass) in the transparent polyimide film. Within range,
When the projected image of the transparent polyimide film is analyzed, the standard deviation σ of the gray value in the 8-bit gray scale is within the range of 0.50 to 1.10, and the occupied area ratio of the black part in the binarized image is 50% or less. A transparent polyimide film for the front plate of a flexible display, which is characterized by being adjusted to.

The transparent polyimide film for a flexible display front plate according to claim 1, wherein the metal oxide particles are silica particles. The transparent polyimide film for a flexible display front plate according to claim 1 or 2 , wherein an aromatic compound is further contained. The aromatic compound is any one of the following aromatic compounds A, the following aromatic compounds B, and the following aromatic compounds C (where n in the formula is 1). The transparent polyimide film for a flexible display front plate according to claim 3.

Any one of claims 1 to 4, wherein the silane coupling agent has at least one group selected from an acrylic group, a methacryl group, an isocyanurate group, a phenyl group and a fluoro group. The transparent polyimide film for the flexible display front plate described in. A method for producing a transparent polyimide film for a flexible display front plate, which contains metal oxide particles, a silane coupling agent, and polyimide.
A step of preparing a dope containing the metal oxide particles, the silane coupling agent, the polyimide, and a solvent.
The step of casting the dope on the support to form a web, and
Have,
The polyimide is one of a polyimide obtained by polymerizing the following acid anhydride B and the following diamine B, and a polyimide obtained by polymerizing the following acid anhydride C, the following diamine C and the following diamine D.
The metal oxide particles have an average primary particle size in the range of 10 to 100 nm, and the content is 20 to 70% by mass with respect to the total solid content (100% by mass) in the transparent polyimide film. Within range,
When the projected image of the transparent polyimide film is evaluated, the standard deviation σ of the gray value in the 8-bit gray scale is within the range of 0.50 to 1.10, and the occupied area ratio of the black portion in the binarized image is 50% or less. A method for producing a transparent polyimide film for a flexible display front plate, which is characterized by adjusting to.

The method for producing a transparent polyimide film for a flexible display front plate according to claim 6 , wherein in the step of preparing the dope, the dope further contains an azeotropic dehydrating agent. An organic electroluminescence display comprising the transparent polyimide film according to any one of claims 1 to 5.

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