JP2018156829A - Transparent polyimide film for flexible display front plate, method for manufacturing the same, and organic electroluminescence display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transparent polyimide film for a flexible display front plate, which can suppress the distortion of an image and is superior in scratch resistance.SOLUTION: A transparent polyimide film for a flexible display front plate according to the present invention comprises: metal oxide particles; a silane coupling agent; and polyimide. The metal oxide particles have an average primary particle diameter within a range of 10-100 nm. When a projection image of the transparent polyimide film is evaluated, a gray value standard deviation σ in a 8 bit gray scale is adjusted to fall within a range of 0.50-1.10, and the percentage of an area occupied by a black portion in a binarized image is adjusted to be 50% or less.SELECTED DRAWING: None

Description

  The present invention relates to a transparent polyimide film for a flexible display front plate, a method for producing the same, and an organic electroluminescence display. The present invention also relates to an organic electroluminescence display.

  Conventionally, glass has been used as a front plate of an organic electroluminescence display (organic EL display). However, with the recent trend toward flexibility, alternative technologies (materials) are desired.

  Transparency, bending resistance, and hardness (scratch resistance) are required for the front panel of flexible displays typified by flexible smartphones. A technology that adds a large amount of silica particles to transparent polyimide is the focus of attention. (For example, refer to 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 oblique direction.
In general, there are many problems in the flatness of the front member as a cause of the distortion of the image on the display. Therefore, the film was re-formed to reduce the surface roughness (Ra) and evaluated again. The distortion did not improve.

US Pat. No. 8,207,256 Japanese Patent Laid-Open No. 2006-93992

  The present invention has been made in view of the above-described problems and circumstances, and its solution is to suppress image distortion and to provide a transparent polyimide film for a flexible display front plate excellent in scratch resistance, a method for producing the same, and organic An electroluminescent display is provided.

  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 the standard deviation σ of the gray value in the 8-bit gray scale is within a specific range. Moreover, a transparent polyimide film for a flexible display front plate, which suppresses image distortion and is excellent in scratch resistance by adjusting the occupied area ratio of a black portion in a binarized image to a specific value or less, and a method for producing the same As a result, the inventors have found that an organic electroluminescence display can be provided, and have reached the present invention.

  That is, the said subject which concerns on this invention is solved by the following means.

1. A transparent polyimide film for a flexible display front plate containing metal oxide particles, a silane coupling agent and a polyimide,
The metal oxide particles have an average primary particle size in the range of 10 to 100 nm and a content of 20 to 70% by mass with respect to the total solid content (100% by mass) in the transparent polyimide film. Is in range,
When evaluating the projected image of the transparent polyimide film, 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 transparent polyimide film for a flexible display front plate, characterized by being adjusted to the above.

  2. 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, further comprising an aromatic compound.

  4). The silane coupling agent has at least one group selected from an acryl group, a methacryl group, an isocyanurate group, a phenyl group, and a fluoro group. Transparent polyimide film for flexible display front plate as described in 1.

  5. The said polyimide is a fluorinated polyimide, The transparent polyimide film for flexible display front plates as described in any one of Claim 1- 4 characterized by the above-mentioned.

6). A method for producing a transparent polyimide film for a flexible display front plate containing metal oxide particles, a silane coupling agent and a polyimide,
Preparing a dope containing the metal oxide particles, the silane coupling agent, the polyimide, and a solvent;
Casting the dope on a support to form a web;
Have
The metal oxide particles have an average primary particle size in the range of 10 to 100 nm and a content of 20 to 70% by mass with respect to the total solid content (100% by mass) in the transparent polyimide film. Is in range,
When evaluating the projected image of the transparent polyimide film, 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. The manufacturing method of the transparent polyimide film for flexible display front plates characterized by adjusting to.

  7). The method for producing a transparent polyimide film for a flexible display front plate according to claim 6, wherein the dope further comprises 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.

  By the above-mentioned means of the present invention, it is possible to provide a transparent polyimide film for a flexible display front plate, a method for producing the same, and an organic electroluminescence display, which suppress image distortion and are excellent in scratch resistance.

  The expression mechanism / action mechanism of the effect of the present invention is not clear, but is presumed 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 a front panel of a flexible display, there is a problem that an image is distorted when the screen is viewed from an oblique direction. Even if the film was re-formed so that Ra) was small, it was not improved.
Therefore, when this polyimide film was observed through a point light source, unevenness was found in the projected image.
This is because water is generated in the reaction when metal oxide particles such as silica particles are introduced into the polyimide, and this causes a partial change in the morphology of the film during film formation. It is presumed that the projection image was observed as unevenness, that is, as distortion of the image on the display.

  Therefore, in the present invention, when the projection 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 black portion in the binarized image is By adopting a transparent polyimide film with an occupied area ratio adjusted to 50% or less as the front plate, it is possible to suppress unevenness of the projected image when viewed with a point light source, that is, distortion of the display image. ing.

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

The schematic diagram which shows the analysis method of the projection image of the transparent polyimide film of this invention

  The transparent polyimide film for a flexible display front plate of the present invention contains metal oxide particles, a silane coupling agent and polyimide, and the metal oxide particles have an average primary particle size in the range of 10 to 100 nm. And, when 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 the projection image of the transparent polyimide film is evaluated, the gray value in an 8-bit gray scale is evaluated. 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 the claimed invention.

  As an embodiment of the present invention, the metal oxide particles are preferably silica particles. Scattering is less likely to occur due to the close refractive index of transparent polyimide and silica, making it more transparent.

  Further, from the viewpoint of effectively removing water generated by dehydration condensation, it is preferable that an aromatic compound is further contained, or that the polyimide is a fluorinated polyimide.

  On the other hand, from the viewpoint of reducing the influence at the time 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 group having a catalytic effect such as an amino group. preferable. Furthermore, considering compatibility with polyimide, the silane coupling agent preferably has at least one group selected from an acrylic group, a methacryl 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 a polyimide, wherein the metal oxide particles, the silane coupling agent, the polyimide, And a step of preparing a dope containing a solvent, and a step of casting a dope on a support to form a web, wherein the metal oxide particles have an average primary particle size of 10 to 100 nm. 8 bit gray when the projection image of the transparent polyimide film is evaluated within the range, and the content is within the range of 20 to 70% by mass with respect to the total solid content (100% by mass) in the transparent polyimide film. The standard deviation σ of the gray value in the scale is in the range of 0.50 to 1.10, and the black area occupation ratio in the binarized image of the rectangular area is 50%. It is possible to provide a method for producing a transparent polyimide film for flexible display front plate is adjusted to below.

  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 comprising the transparent polyimide film.

  Hereinafter, the present invention, its components, and modes and modes for carrying out the present invention will be described in detail. In addition, in this application, "-" showing a numerical range is used by the meaning containing the numerical value described before and behind that as a lower limit and an upper limit.

<Transparent polyimide film>
The transparent polyimide film for a flexible display front plate of the present invention (hereinafter also simply referred to as a polyimide film or film) contains metal oxide particles, a silane coupling agent, and polyimide, and is an average primary of metal oxide particles. When the projected image of a transparent polyimide film having a particle size in the range of 10 to 100 nm is evaluated, the gray value standard deviation σ in the 8-bit gray scale is in the range of 0.50 to 1.10. The occupied area ratio of the black portion in the image is adjusted to 50% or less.
Here, the term “transparent” 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 black area occupation ratio in binarized image>

FIG. 1 is a schematic view showing a method for analyzing a projected image of a 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 Technical Center Co., Ltd.) is adjusted to 60 cm, and the light from the white light source 2 to the film sample 1 is obliquely viewed from a 45 ° direction. Irradiate. The distance between the film sample 1 and the projection surface 3 arranged in parallel with 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 KISS50, lens EF-S 18 = 55 mm, ISO sensitivity 100, aperture 5.6, shutter speed) disposed at a distance of 80 cm in the direction of 90 ° from the projection plane 3. 1/10 seconds, white balance (manual setting))
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, the standard deviation σ of the gray value and the occupied area ratio K (%) of the black portion in the binarized image are calculated for the obtained projection image according to the following procedures 1 to 7.

1. The captured image is read into a personal computer using free software ImageJ.
2. A rectangular evaluation area of 1 cm × 5 cm is set in an actual captured image. At this time, the long side of the rectangle is set to the film sample transport direction.
3. Using the free software ImageJ, 8-bit gray scale is performed.
4). Background correction is performed by the free software ImageJ.
5. A standard deviation σ and an average value m of gray values (pixel values) in a gray scale are calculated.
6). The binarization of the rectangular evaluation area is performed using the average value m as a threshold value.
7. Divide the area of the black part (dark part) obtained by binarization by the entire area to calculate the occupation ratio K (%) of the black part.

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

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

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

The gray value N pieces of data x ₁ , x ₂ ,..., X _N are defined as a population, and an arithmetic average (population average) m of the population is obtained by the following formula (1).

Next, the variance σ ² is obtained by the following mathematical formula (2) using the population average m obtained above.

The positive square root of the variance σ ² is defined as a standard deviation σ.

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

  Moreover, although the occupied area ratio of the black part in the binarized image of the rectangular area of the transparent polyimide film of the present invention is adjusted to 50% or less, considering the range that is not visually recognized as unevenness and the productivity, 40 to 50 % Is 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 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 part containing (—C (═O)) ₂ —R— (C (═O) —) ₂ is a part derived from an acid anhydride or a derivative thereof, and ═N—A— The portion containing N = is a portion derived from diamine or a derivative thereof.

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

When R is a combination of any two or more of the above, these 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 consisting of

In addition, at least one hydrogen atom in the aromatic hydrocarbon ring, aromatic heterocyclic ring, aliphatic hydrocarbon having 4 to 39 carbon atoms or alicyclic hydrocarbon represented by R is a halogen atom (for example, 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 and the like, or a halogenated alkyl group 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, may be substituted with -CH 2 -CHF _2), etc.).

  Examples of the aromatic hydrocarbon ring represented by R include fluorene ring, benzene ring, biphenyl ring, naphthalene ring, azulene ring, anthracene ring, phenanthrene ring, pyrene ring, chrysene ring, naphthacene ring, triphenylene ring, o- Terphenyl ring, m-terphenyl ring, p-terphenyl ring, acenaphthene ring, coronene ring, fluoranthrene ring, naphthacene ring, pentacene ring, perylene ring, pentaphen ring, picene ring, pyrene ring, pyranthrene ring, anthraanthre Ring.

  Examples of the aromatic heterocycle represented by R include a silole 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 oxadiazole ring, and a triazole. 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 Any one or more of carbon atoms to be replaced by nitrogen atoms), dibenzosilole ring, dibenzofuran ring, dibenzothiophene ring, benzothiophene ring or dibenzofuran ring Replaced ring Benzodifuran ring, benzodithiophene ring, acridine ring, benzoquinoline ring, phenazine ring, phenanthridine ring, phenanthroline ring, cyclazine ring, kindlin ring, tepenidine ring, quinindrine ring, triphenodithiazine ring, triphenodioxazine ring, phenodine Nantrazine ring, anthrazine ring, perimidine ring, naphthofuran ring, naphthothiophene ring, naphthodifuran ring, naphthodithiophene ring, anthrafuran ring, anthradifuran ring, anthrathiophene ring, anthradithiophene ring, thianthrene ring, phenoxathiin ring , Dibenzocarbazole ring, indolocarbazole ring, dithienobenzene ring and the like.

  Examples of the tetravalent aliphatic hydrocarbon group having 4 to 39 carbon atoms represented by R include a butane-1,1,4,4-triyl group, an octane-1,1,8,8-triyl group, Examples include decane-1,1,10,10-triyl group.

  Examples of the tetravalent alicyclic hydrocarbon group having 4 to 39 carbon atoms represented by R include a cyclobutane-1,2,3,4-tetrayl group and a cyclopentane-1,2,4,5-tetrayl group. Group, cyclohexane-1,2,4,5-tetrayl group, bicyclo [2.2.2] oct-7-ene-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 Examples include -1,2,4,5-tetrayl group.

  Among these, R is preferably a group R-1 to R-4 represented by the following structural formula.

  R is preferably a group R-1 to R-3, particularly preferably a group R-1.

When A is a combination of any two or more of the above, these 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 C1-C3 divalent aliphatic hydrocarbon group, alicyclic hydrocarbon group or aromatic hydrocarbon ring group represented by A 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 and the like, or a halogenated alkyl group thereof (for example, monofluoromethyl group (—CFH ₂₎ ), difluoromethyl group _(-CF 2 H), trifluoromethyl group _(-CF 3), monofluoroethyl group (-CHF-C _{3, -CH 2 -CH 2 F)} , difluoroethyl group _{(-CF 2 -CH 3, -CHF-} CH 2 F, may be substituted with -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, 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 above linking group represented by A include groups A3-1 to A3-12 represented by the following structural formulas, for example. Is mentioned.

  Examples of the group consisting of a combination of an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, and an aromatic hydrocarbon ring group represented by A include groups A4-1 to A4-26 represented by the following structural formula. Can be mentioned.

  Among them, A is preferably a group A4-7, A4-23, A4-25, or A4-26, more preferably a group A4-7 or A4-25, or a group A4-25. Particularly preferred.

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 the silane coupling agent.
From the above, the polyimide preferably has a structure in which R is a group R-1 and A is a group A4-25.

  In addition, when a polyimide is a fluorinated polyimide, the content rate of a fluorine atom is although it does not restrict | limit in particular, It is preferable that it is about 1-40 mass% in a film. If it is such quantity, the film obtained is excellent in transparency and is easy to perform heat correction by heat shrink.

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%, still more preferably 80 to 100 mol% with respect to all the repeating units. 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. In this range, the glass transition temperature is further 230 to 350 ° C. Is preferably within 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, a polyimide is synthesized 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 do.

  Examples of the aromatic tetracarboxylic acid include 4,4′-biphthalic anhydride, 4,4 ′-(hexafluoroisopropylidene) diphthalic anhydride, and 2,3,3 ′, 4′-biphenyltetracarboxylic acid. Dianhydride, 4,4'-oxydiphthalic anhydride, 3,3 ', 4,4'-benzophenonetetracarboxylic dianhydride, 4- (2,5-dioxotetrahydrofuran-3-yl) -1, 2,3,4-tetrahydronaphthalene-1,2-dicarboxylic anhydride, 3,3 ', 4,4'-diphenylsulfone tetracarboxylic dianhydride, 3,4'-oxydiphthalic anhydride, 3,4 , 9,10-perylenetetracarboxylic dianhydride (Pigment Red 224), 2,3,6,7-naphthalenetetracarboxylic dianhydride, 2,2-bis (4- (3,4-dicarbo) Ciphenoxy) phenyl) propane dianhydride, 9,9-bis (3,4-dicarboxyphenyl) fluorene, 9,9-bis [4- (3,4-dicarboxyphenoxy) -phenyl] fluorene anhydride, etc. Is mentioned.

  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 acid, 1,2,4,5-cyclopentanetetracarboxylic acid, 1,2,4,5-cyclohexanetetracarboxylic acid. Bicyclo [2.2.2] oct-7-ene-2,3,5,6-tetracarboxylic acid, bicyclo [2.2.2] octane-2,3,5,6-tetracarboxylic acid, and the like. Can be mentioned.

Examples of the aliphatic or alicyclic tetracarboxylic acid derivatives include aliphatic or alicyclic tetracarboxylic acid esters, aliphatic or alicyclic tetracarboxylic dianhydrides, and the like.
Of the aliphatic or alicyclic tetracarboxylic acids or derivatives thereof, alicyclic tetracarboxylic dianhydrides are preferred.

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 dianhydride, a compound having two carboxy groups instead of the anhydride A compound in which one or both of these two carboxy groups is an esterified product, 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), it is possible to obtain a polyimide film having high heat resistance and excellent optical properties and less coloring (yellowing).

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

  Examples of the alicyclic tetracarboxylic acid esters include monoalkyl esters, dialkyl esters, trialkyl esters, and tetraalkyl esters of the above alicyclic tetracarboxylic acids. In addition, it is preferable that an alkyl group site | part is a C1-C5 alkyl group, and it is more preferable that it is a C1-C3 alkyl group.

  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 include octane-2,3,5,6-tetracarboxylic dianhydride and 2,3,5-tricarboxycyclopentylacetic acid dianhydride. Particularly preferred is 1,2,4,5-cyclohexanetetracarboxylic dianhydride.

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

  Other examples include 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 acid anhydride or 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 unique 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 acid dianhydride, 9,9-bis [4- (3,4-dicarboxyphenoxy) -3-phenylphenyl] fluoric acid dianhydride, and the like can be used.

Aromatic, aliphatic or alicyclic tetracarboxylic acid, or a derivative thereof may be used alone or in combination of two or more.
Further, other tetracarboxylic acids or derivatives thereof (particularly acid dianhydrides) may be used in combination as long as the solvent solubility of polyimide, the flexibility of the polyimide film, thermocompression bonding, and 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, 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′-benzophenonetetracarboxylic acid, 2,2 , 3,3'-benzophenonetetracarboxylic acid, 4,4- (p-phenylenedioxy) diphthalic acid, 4,4- (m-phenylenedioxy) diphthalic acid, 1,1-bis (2,3-di Aromatic tetracarboxylic acids such as carboxyphenyl) ethane, bis (2,3-dicarboxyphenyl) methane, bis (3,4-dicarboxyphenyl) methane and their derivatives (particularly acid dianhydrides), ethylenetetra Examples thereof include aliphatic tetracarboxylic acids having 1 to 3 carbon atoms such as carboxylic acids and derivatives thereof (particularly acid dianhydrides).

  Examples of acid dianhydrides include 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride, biphenyltetracarboxylic dianhydride, pyromellitic acid anhydride, 4,4'-oxydiphthalic acid anhydride It is preferable from the viewpoint of excellent transparency and easy thermal correction by heat shrinkage. In addition, from the viewpoint of further suppressing yellowing and turbidity in an environment where temperature and humidity fluctuate (especially high temperature and high humidity environment), 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dian More preferred is hydride.

A part containing (—C (═O)) ₂ —R— (C (═O) —) ₂ in the above general formula (1) (part derived from an acid anhydride or a derivative thereof) is arbitrarily mixed and used. However, the content of the preferable portion derived from the acid dianhydride is preferably in the range of 50 to 100 mol%, and more preferably in the range of 80 to 100 mol%.

The diamine or derivative thereof may be, for example, an aromatic diamine, an aliphatic diamine, an isocyanate, or a mixture thereof, and is preferably an aromatic diamine 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, and other substitutions are part of the structure. A group (for example, a halogen atom, a sulfonyl group, a carbonyl group, an oxygen atom, etc.) may be contained. The 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 or other substituent (for example, a part of the structure) , A halogen atom, a sulfonyl group, a carbonyl group, an oxygen atom, etc.).

  Examples of aromatic diamines include, for example, p-phenylenediamine, m-phenylenediamine, 2,4-diaminotoluene, 2,6-diaminotoluene, benzidine, o-tolidine, m-tolidine, 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'-di Minodiphenylsulfone, 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, -Dimethyl-4-aminophenoxy) biphenyl, 4,4'-bis (3-aminophenoxy) biphenyl, bis (4- (4-aminophenoxy) phenyl) sulfone, bis (4- (2-methyl-4-amino) Phenoxy) 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, 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) Xafluoropropane, 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-amino) Phenyl) 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) norbornane, 1,1-bis (2-methyl-4-aminophenyl) norbornane, 1,1-bis (2,6-dimethyl-4) -Aminophenyl) norbornane, 1,1-bis (4-aminophenyl) adamantane, 1,1-bis (2-methyl-4-aminophenyl) adamanta 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-amino Phenoxy) 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'-diamidine -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 ′-[isopropylidenebis [(4,1-phenylene) oxy]] bisaniline, bis (aminomethyl) norbornane, and the like.

  Examples of the aliphatic diamine include ethylene diamine, hexamethylene diamine, polyethylene glycol bis (3-aminopropyl) ether, polypropylene glycol bis (3-aminopropyl) ether, 1,3-bis (aminomethyl) cyclohexane, 1,4. -Bis (aminomethyl) cyclohexane, m-xylylenediamine, p-xylylenediamine, 1,4-bis (2-amino-isopropyl) benzene, 1,3-bis (2-amino-isopropyl) benzene, isophoronediamine , Norbornanediamine, siloxane diamine, 4,4′-diaminodicyclohexylmethane, 3,3′-dimethyl-4,4′-diaminodicyclohexylmethane, 3,3′-diethyl-4,4′-diaminodicyclohexylmethane, 3, 3 ', , 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-bis (4 4'-diaminomethylcyclohexyl) propane and the like.

Moreover, you may use the diamine which has a fluorene skeleton, or its derivative (s) for the purpose of improving coloring peculiar to a polyimide.
Examples of the diamine having a fluorene skeleton or derivatives thereof include 9,9-bis [4- (4-aminophenoxy) phenyl] fluorene and 9,9-bis [4- (4-aminophenoxy) -3-phenylphenyl. Fluorene, 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.

  Moreover, you may use the diamine which has a structure represented by following General formula (2) which has a triazine mother nucleus.

In 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 having 1 to 12 carbon atoms or an aryl group. 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, more preferably an alkyl group having 1 to 6 carbon atoms.
The 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, 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 bonded to the two NH groups of triazine is 4-aminoanilino or 3-aminoanilino, which may be the same or different, but 4-aminoanilino is preferred.

  As the diamine having the structure represented by the above general formula (2) having a triazine mother nucleus, specifically, 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 -Amino Nilino) -6-diphenylamino-1,3,5-triazine, 2,4-bis (4-aminoanilino) -6-dibenzylamino-1,3,5-triazine, 2,4-bis (4-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) − -Ethylamino-1,3,5-triazine, 2,4-bis (4-aminoanilino) -6-dimethylamino-1,3,5-triazine, 2,4-bis (3-aminoanilino) -6-dimethyl Amino-1,3,5-triazine, 2,4-bis (4-aminoanilino) -6-diethylamino-1,3,5-triazine, 2,4-bis (4-aminoanilino) -6-dibutylamino-1 , 3,5-triazine, 2,4-bis (4-aminoanilino) -6-amino-1,3,5-triazine, 2,4-bis (3-aminoanilino) -6-amino-1,3,5 -Triazine etc. are mentioned.

  As isocyanate ester which is a diamine derivative, the diisocyanate obtained by making the said aromatic or aliphatic diamine and phosgene react is mentioned, for example.

  Examples of other diamine derivatives include diaminodisilanes, such as trimethylsilylated aromatic or aliphatic diamine obtained by reacting the above aromatic or aliphatic diamine with chlorotrimethylsilane.

  Examples of the diamine include 2,2′-bis (trifluoromethyl) -4,4′-diaminobiphenyl, 2,5-diethyl-4,6-dimethylbenzene-1,3-diamine, 4,4 ′-[isopropylate. Redenbis [(4,1-phenylene) oxy]] bisaniline and bis (aminomethyl) norbornane are preferred. From the viewpoint of further suppressing yellowing and turbidity in an environment where temperature and humidity vary (particularly high temperature and high humidity), 2,2'-bis (trifluoromethyl) -4,4'-diamino Biphenyl and bis (aminomethyl) norbornane are more preferred, and 2,2′-bis (trifluoromethyl) -4,4′-diaminobiphenyl is particularly preferred.

  In the above general formula (1), a portion containing ═N—A—N═ (a portion derived from a diamine or a derivative thereof) may be arbitrarily mixed and used. The total content is preferably in the range of 20 to 80 mol%, and more preferably in the range of 40 to 60 mol%.

Polyamic acid is synthesized by reacting tetracarboxylic acid or a derivative thereof with diamine or a derivative thereof. Specifically, the polyamic acid is obtained by polymerizing at least one tetracarboxylic acid and at least one diamine in a suitable solvent.
The polyamic acid ester is diesterified by opening the tetracarboxylic dianhydride with an alcohol such as methanol, ethanol, isopropanol, or n-propanol, and the resulting diester is reacted with a diamine in an appropriate solvent. Can be obtained. Furthermore, the polyamic acid ester can also be obtained by esterification by reacting the carboxylic acid group of the polyamic acid obtained as described above with an alcohol as described above.

The reaction of tetracarboxylic dianhydride and diamine can be carried out under conventionally known conditions. There are no particular limitations on the order and method of addition of tetracarboxylic dianhydride and diamine. For example, tetracarboxylic dianhydride and diamine are sequentially added to a solvent, and a polyamic acid can be obtained by stirring at an appropriate temperature.
The amount of diamine is not particularly limited, and is preferably such an amount that provides the preferred 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 making the amount of diamine within such a range, the yield of the polyamic acid obtained can be improved.

  Examples of the polymerization solvent used in this reaction include hydrocarbon solvents such as hexane, cyclohexane, heptane, benzene, toluene, xylene and mesitylene, carbon tetrachloride, dichloromethane, chloroform, 1,2-dichloroethane, chlorobenzene and dichlorobenzene. Halogenated hydrocarbon solvents such as fluorobenzene, ether solvents such as diethyl ether, tetrahydrofuran, 1,4-dioxane and methoxybenzene, ketone solvents such as acetone and methyl ethyl ketone, N, N-dimethylformamide, N, N- Amide solvents such as dimethylacetamide and N-methyl-2-pyrrolidone, aprotic polar solvents such as dimethyl sulfoxide and γ-butyrolactone, heterocyclic solvents such as pyridine, picoline, lutidine, quinoline and isoquinoline, Phenol, phenolic solvents such as cresol, and the like, but not particularly limited. As a polymerization solvent, only 1 type can also be used and 2 or more types of solvents can also be mixed and used.

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

  The reaction temperature is not particularly limited, but is usually 0 ° C. or higher, preferably 20 ° C. or higher, and is usually 100 ° C. or lower, preferably 80 ° C. or lower. The reaction time is not particularly limited, but is usually 1 hour or longer, preferably 2 hours or longer, and is usually 100 hours or shorter, preferably 24 hours or shorter. By performing the reaction under such conditions, the polyamic acid can be obtained at a low cost and in a high yield.

As the terminal group of the polyamic acid, an acid anhydride group or an amino group can be arbitrarily selected by using either one of tetracarboxylic dianhydride and diamine in the polymerization reaction in excess.
When the terminal group is an acid anhydride group, the terminal of the acid anhydride may be left without performing the subsequent treatment, or may be hydrolyzed to form a dicarboxylic acid. Moreover, it is good also as ester using C4 or less alcohol. Furthermore, you may seal a terminal | end using monofunctional amine or isocyanate. 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, phenyl isocyanate, xylylene isocyanate, cyclohexyl isocyanate, Examples thereof include methylphenyl isocyanate and trifluoromethylphenyl isocyanate.

  When the terminal group is an amino group, it is possible to avoid the amino group remaining at the terminal by sealing the terminal amino group with a monofunctional acid anhydride. As an acid anhydride used here, if it is a monofunctional acid anhydride which becomes dicarboxylic acid or tricarboxylic acid when hydrolyzed, it can be used without particular limitation. For example, maleic anhydride, methyl maleic anhydride, dimethyl maleic anhydride, succinic anhydride, norbornene dicarboxylic anhydride, 4- (phenylethynyl) phthalic anhydride, 4-ethynyl phthalic anhydride, phthalate Acid anhydride, methylphthalic anhydride, dimethylphthalic anhydride, trimellitic anhydride, naphthalenedicarboxylic anhydride, 7-oxabicyclo [2.2.1] heptane-2,3-dicarboxylic anhydride, bicyclo [2.2.1] Heptane-2,3-dicarboxylic anhydride, bicyclo [2.2.2] oct-5-ene-2,3-dicarboxylic anhydride, 4-oxatricyclo [5.2 2.02,6] undecane-3,5-dione, octahydro-1,3-dioxoisobenzofuran-5-carboxylic acid, hexahydrophthalic anhydride Methyl hexahydrophthalic anhydride, dimethyl cyclohexane dicarboxylic acid anhydride, 1,2,3,6-tetrahydrophthalic anhydride, methyl-4-cyclohexene-1,2-dicarboxylic anhydride and the like.

Next, the polyamic acid (preferably in the form of a solution) obtained as described above is heated to imidize the polyamic acid (thermal imidization method), or a ring-closing catalyst (imidization catalyst) is added to the polyamic acid solution. A polyimide can be obtained by a method of adding and imidizing polyamic acid (chemical imidization method).
In the thermal imidization method or chemical imidization method, a reaction vessel for polymerizing polyamic acid from an acid anhydride and a diamine may be continued as it is and imidized in the reaction vessel.

In the thermal imidization method in the reaction kettle, the polyamic acid in the polymerization solvent is, for example, in the temperature range of 80 to 300 ° C. for 0.1 to 200 hours (preferably 1 to 100 hours, more preferably 3 to 50 hours). Time) Heat treatment is performed to advance imidization. Moreover, it is preferable that the said temperature range shall be 150-200 degreeC, By making it 150 degreeC or more, imidation can be made to advance reliably and can be completed, On the other hand, by making it 200 degrees C or less, a solvent and It is possible to prevent an increase in the resin concentration due to oxidation of unreacted raw materials and volatilization of the solvent.
Furthermore, in the thermal imidization method, an azeotropic solvent can be added to the polymerization solvent in order to efficiently remove water generated by the imidization reaction. As the azeotropic 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 using an azeotropic solvent, the addition amount is about 1 to 30% by mass, preferably 5 to 20% by mass in the total amount of 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 advance 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 picoline. Examples thereof include 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, particularly 1,2-dimethyl. Lower alkyl imidazole such as imidazole, N-methylimidazole, N-benzyl-2-methylimidazole, 2-methylimidazole, 2-ethyl-4-methylimidazole, 5-methylbenzimidazole, N-benzyl-2-methylimidazole, etc. Imidazole derivatives, isoquinoline, 3,5-dimethylpi Jin, 3,4-dimethylpyridine, 2,5-dimethylpyridine, 2,4-dimethylpyridine, substituted pyridine, such as 4-n-propyl pyridine, can be suitably used p- toluenesulfonic acid and the like.
The addition amount of the ring-closing catalyst is preferably within a range of 0.01 to 2 equivalents, particularly preferably within a range of 0.02 to 1 equivalents with respect to the amic acid unit of the polyamic acid. By using a ring-closing catalyst, the properties of the resulting polyimide, particularly elongation and breaking resistance, may be improved.

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

  Thus, the polyimide solution imidized in the reaction kettle is advantageous because it is less likely to cause a decrease in molecular weight due to hydrolysis over time than the polyimide solution. In addition, since the imidization reaction has progressed in advance, for example, in the case of a polyimide having an imidization rate of 100%, imidization on the web is 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 obtain a solid, then dissolved in a solvent and cast and dried to form a film.
According to this method, the polymerization solvent and the solvent to be cast can be made different types, and the performance of the polyimide film can be further extracted by selecting an optimum solvent for each.
For example, in order to increase the molecular weight of polyamic acid, it is polymerized and cyclized with dimethylacetamide, solidified with methanol, dried, then redissolved in dichloromethane, cast, and dried to increase the molecular weight. And low temperature drying.
Moreover, when using dichloromethane as a solvent, it can be used in combination with other solvents. For example, an auxiliary solvent such as tetrahydrofuran (THF), dioxolane, cyclohexanone, cyclopentanone, γ-butyrolactone, ethanol, methanol, butanol, or isopropyl alcohol can be appropriately used.

In addition to the polyimide described above, polyimide containing atoms such as phosphorus, silicon, and sulfur can also be used.
For example, as polyimide containing phosphorus, use polyimides described in paragraphs [0010]-[0021] of JP2011-74209A and paragraphs [0011]-[0025] of JP2011-074177A, respectively. Can do.
As a polyimide containing silicon, a polyimide obtained by imidizing a polyimide precursor described in paragraphs [0030]-[0045] of JP2013-028796A can be used.
Examples of the polyimide containing sulfur include paragraphs [0009]-[0025] of JP 2010-189322 A, paragraphs [0012]-[0025] of JP 2008-274234 A, and paragraphs of JP 2008-274229 A. Polyimides obtained by imidizing a polyimide precursor described in each of [0012]-[0023] can be used.
In addition, the alicyclic polyimide described in paragraphs [0008]-[0012] of JP-A-2009-256590 and paragraphs [0008]-[0012] of JP-A-2009-256589 are preferably used. it can.

  In addition to the polyimide described above, polyamideimide can also be used. Polyamideimide contains tricarboxylic acid, tetracarboxylic acid or dicarboxylic acid as an acid component, and diamine as a structural 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 -1,2,4-tricarboxylic acid, monoanhydrides such as tricarboxylic acid such as butane-1,2,4-tricarboxylic acid, esterified compounds, or a mixture of two or more

  b) Tetracarboxylic acid: 3,3,4 ', 4'-benzophenonetetracarboxylic acid, 3,3,4', 4'-biphenyltetracarboxylic acid, diphenylsulfone-3,3 ', 4,4'-tetra Carboxylic 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 acid monoanhydride, dianhydride, esterified compound or the like, or a mixture of two or more thereof

  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 component includes 3,3'-dimethyl-4,4'-diaminobiphenyl, 3,3'-diethyl-4,4'-diaminobiphenyl, 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'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, 3,4'-diaminobiphenyl, 3 , 3'-diaminobiphenyl, 3,3'-diaminobenzanilide, 4,4'-diaminobenzanilide, 4,4 ' Diaminobenzophenone, 3,3'-diaminobenzophenone, 3,4'-diaminobenzophenone, 2,6-tolylenediamine, 2,4-tolylenediamine, 4,4'-diaminodiphenyl sulfide, 3,3'-diamino Diphenyl sulfide, 4,4'-diaminodiphenylpropane, 3,3'-diaminodiphenylpropane, 3,3'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, p-xylenediamine, m-xylenediamine, 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, bi [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, tetramethylenediamine, hexamethylenediamine, isophoronediamine, 4,4′-dicyclohexylmethanediamine, cyclohexane-1,4-diamine, diaminosiloxane, 1,5-naphthalenediamine or the corresponding diisocyanate alone or a mixture of two or more thereof may be mentioned.

  In particular, trimellitic anhydride (TMA), 3,3,4 ', 4'-benzophenonetetracarboxylic dianhydride (BTDA), and 3,3,4', 4'-biphenyltetracarboxylic acid as acid components Polyamideimide polymerized with a raw material containing dianhydride (BPDA) and 1,5-naphthalene diisocyanate (NDI) as an isocyanate component is preferable.

  The value of the molar ratio between the imide bond and the amide bond of the polyamideimide is preferably in the range of 99/1 to 60/40, more preferably in the range of 99/1 to 75/25, and still more preferably 90 / It is in the range of 10-80 / 20. When the value of the molar ratio of the imide bond to the amide bond is 60/40 or more, the heat resistance, moisture resistance reliability, and heat resistance reliability are improved. On the other hand, if it is 99/1 or less, the elastic modulus tends to be low, and the folding resistance and bending characteristics tend to be improved.

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

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

In 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 More preferably, = 0.

  In 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-naphthalene diisocyanate, general formula (4) is a repeating unit from terephthalic acid and 1,5-naphthalene diisocyanate, (5) is a repeating unit from biphenyltetracarboxylic dianhydride or benzophenone tetracarboxylic dianhydride and 1,5-naphthalene diisocyanate, and the content ratio is represented by formula (3) / {general formula (4) + general The formula (5) + the formula (6)} = 1/99 to 40/60 mol ratio, and the general formula (4) / general formula (5) = 10/90 to 90/10 mol ratio is preferable.

  The higher the imidization rate, the better. The upper limit is 100%. The polyamideimide 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.), etc. In the present invention, the polyamideimide 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 polyimide described above, a polyamideimide containing a repeating unit represented by the following general formula (7) can also be used.

In General Formula (7), R ⁴ represents an aryl group or a cycloalkane group.
In this case, the aryl group or 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 can be included in the polyamideimide include p-phenylenediamine, 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-tolylenediamine, 2,4-tolylenediamine, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfide, 4,4 '-Diaminodiphenylpropane, 3,3'-dia Nodiphenylpropane, 3,3'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, p-xylenediamine, m-xylenediamine, 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, dicyclohexylmethane-4,4′-diamine (trans isomer, cis isomer) , 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-diaminoadamantane, 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, 1, -Propanediamine, 1,4-tetramethylenediamine, 1,5-pentamethylenediamine, 1,6-hexamethylenediamine, 1,7-heptamethylenediamine, 1,8-octamethylenediamine, 1,9-nonamethylene A single or a mixture of two or more of diamines, or a single or a mixture of two or more of the corresponding diisocyanates can be used as the diamine component.
Preferably, 3,3′-dimethyl-4,4′-diaminobiphenyl, dicyclohexylmethane-4,4′-diamine (trans isomer, cis isomer, trans / cis mixture), 4,4′-diaminodiphenyl ether, p -Phenylenediamine, 4-methyl-1,3-phenylenediamine and the like alone or a mixture of two or more thereof, or diisocyanates corresponding to these alone or a mixture of two or more can be used as the diamine component.
More preferably, 3,3′-dimethyl-4,4′-diaminobiphenyl, dicyclohexylmethane-4,4′-diamine (trans isomer, cis isomer, trans / cis mixture), 4,4′-diaminodiphenyl ether, A single or a mixture of two or more of 4-methyl-1,3-phenylenediamine or the like, or a single or a mixture of two or more of the corresponding diisocyanates can be used as the diamine component.
More preferably, 3,3′-dimethyl-4,4′-diaminobiphenyl, dicyclohexylmethane-4,4′-diamine (trans isomer, cis isomer, trans / cis mixture), 4-methyl-1,3- A single or a mixture of two or more of phenylenediamine or the like, or a single or a mixture of two or more of the corresponding diisocyanates can be used as the diamine component.

Among the above acid component and diamine component, the following components are preferable from the viewpoint of heat resistance, solvent resistance, and durability in the process of forming a film, and heat resistance, surface smoothness, and transparency of the produced polyamideimide film. Used.
As the acid component, cyclohexane-1,2,4-tricarboxylic acid-1,2-anhydride 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-tolidine diisocyanate) and 4-methyl-1,3-phenylene diisocyanate (tolylene diisocyanate) can be used. .

  Moreover, as a preferable polyamideimide, a compound containing a repeating unit represented by the following general formula (8) can be used.

In General Formula (8), R ⁵ and R ⁶ each independently represent a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or an aryl group.
In this case, the alkyl group or 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, and a biphenyl group.

When the total acid component is 100 mol%, the exemplified acid component is preferably contained within a range of 50 to 100 mol%, and more preferably within a range of 70 to 100 mol%.
Moreover, when all the diamine components are made into 100 mol%, it is preferable that the illustrated diamine component is contained in the range of 50-100 mol%, and it is more preferable that it is contained in the range of 70-100 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 resulting polyamideimide film are particularly improved.

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 to be reduced are preferable, and more preferably those having a molecular weight corresponding to the range of 0.5 to 2.0 cm ³ / g. When the logarithmic viscosity is 0.3 cm ³ / g or more, mechanical properties are sufficient when formed into a molded product such as a film. 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 polyimide described above, polyetherimide can also be used. Here, the polyetherimide is a thermoplastic resin having an aromatic nucleus bond and an imide bond in its structural unit, and is not particularly limited. Specifically, the polyetherimide is represented by the following formula (9) or (10). It is preferable that it is a polyetherimide which has a repeating unit.

  As polyetherimide having a repeating unit represented by the above formula (9), trade names “Ultem 1000” (glass transition temperature: 216 ° C.) and “Ultem 1010” (glass transition temperature: 216 ° C.) manufactured by General Electric Co., Ltd. ), Polyetherimide having a repeating unit represented by the above formula (10) includes “Ultem CRS5001” (glass transition temperature Tg 226 ° C.), and other specific examples are trade names of Mitsui Chemicals, Inc. “Aurum (registered trademark) PL500AM” (glass transition temperature: 258 ° C.).

The method for synthesizing the polyetherimide is not particularly limited. Usually, the amorphous polyetherimide having the repeating unit represented by the above formula (9) is 4,4 ′-[isopropylidenebis (p -Phenyleneoxy)] diphthalic acid dianhydride and m-phenylenediamine as a polycondensate, and polyetherimide having a repeating unit represented by the above formula (10) is 4,4 '-[isopropylidene It is synthesized by a known method as a polycondensate of bis (p-phenyleneoxy)] diphthalic 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 within the range not exceeding the gist of the present invention. In addition, polyetherimide can be used individually by 1 type or in combination of 2 or more types.

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

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

  A divalent chain aliphatic group, a divalent cycloaliphatic group or a divalent aromatic group is a chain aliphatic compound having a divalent hydroxy group, and a cyclic fat having a divalent hydroxy group, respectively. It is desirable that the residue be derived from a diol such as an aromatic compound having a divalent hydroxy group. Moreover, the residue derived from the polycarbonate diol which can be polymerized from the said diol, carbonate ester, phosgene, etc. may be sufficient.

  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, 1,6-hexanediol, 1,8-octanediol, 2-methyl-1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,4-cyclohexanediol, 1,4- And cyclohexanedimethanol.

  Examples of the polyoxyalkylene diol include dimethylolpropionic acid (2,2-bis (hydroxymethyl) propionic acid), dimethylolbutanoic acid (2,2-bis (hydroxymethyl) butanoic acid), polyethylene glycol, polypropylene glycol, Examples include polytetramethylene glycol, polyoxytetramethylene glycol, and a random copolymer of tetramethylene glycol and neopentyl glycol. Polyoxytetramethylene glycol is preferable.

Examples of the polyester diol include polyester diols obtained by reacting polyhydric alcohols and polybasic acids exemplified below.
As the “polyhydric alcohol component” used in the polyester diol, any of 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 , 1,10-dodecane diol, 2-butyl-2-ethyl-1,3-propanediol, tricyclodecane dimethanol, polyethylene glycol, polypropylene glycol, polyether polyol such as polytetramethylene glycol may be used.
Arbitrary various polybasic acids can be used as a polybasic acid component used for polyester diol. 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, 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. Aliphatic and alicyclic dibasic acids can be used.
As a commercially available product of polyester diol, specifically, ODX-688 (DIC Co., Ltd. aliphatic polyester diol: 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).

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

  Examples of the cycloaliphatic 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, two phenols or an alicyclic alcohol. A compound bonded with a divalent functional group, a compound having one hydroxy group in both nuclei of the biphenyl structure, a compound having two hydroxy groups in the naphthalene skeleton, and the like are used.

  The compounds having two hydroxy groups in the aromatic ring or cyclohexane ring include hydroquinone, 2-methylhydroquinone, resorcinol, catechol, 2-phenylhydroquinone, cyclohexanedimethanol, tricyclodecanedimethanol, 1,4-dihydroxycyclohexane, 1 , 3-dihydroxycyclohexane, 1,2-dihydroxycyclohexane, 1,3-adamantanediol, 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.

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

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

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

  The number average molecular weight of the diol is preferably in the range of 100 to 30000, more preferably in the range of 150 to 20000, and still more preferably in the range of 200 to 10,000. When the number average molecular weight is in the above range, it is possible to sufficiently exhibit hygroscopicity, flexibility, mechanical properties, and colorless transparency.

  The polycarbonate diol may be a polycarbonate diol having a plurality of types of alkylene groups in the skeleton (copolymerized polycarbonate diol). 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, 1,5-pentanediol and 1 Copolycarbonate diols that can be synthesized by a combination of 1,6-hexanediol and the like. A copolymer polycarbonate diol that can be synthesized from a combination of 2-methyl-1,8-octanediol and 1,9-nonanediol is preferable. Two or more of these polycarbonate diols can be used in combination.

  Commercially available polycarbonate diols include Kuraray Kuraray Polyol C Series, Asahi Kasei Chemicals Duranol Series, and the like. For example, Kuraray polyol C-1015N, Kuraray polyol C-1065N (Kuraray Co., Ltd. carbonate diol: 2-methyl-1,8-octanediol / 1,9-nonanediol, number average molecular weight about 1000), Kuraray polyol C -2015N, Kuraray polyol C2065N (Kuraray Co., Ltd. carbonate diol: 2-methyl-1,8-octanediol / 1,9-nonanediol, number average molecular weight of about 2000), Kuraray polyol C-1050, Kuraray polyol C- 1090 (Kuraray Co., Ltd. carbonate diol: 3-methyl-1,5-pentanediol / 1,6-hexanediol, number average molecular weight about 1000), Kuraray polyol C-2050, Kuraray polyol C-2090 (Corporation) Kuraray carbonate diol: 3 Methyl-1,5-pentanediol / 1,6-hexanediol, number average molecular weight of about 2000), Duranol T5650E (Asahi Kasei Chemicals Corporation polycarbonate diol: 1,5-pentanediol / 1,6-hexanediol, number Average molecular weight of about 500), Duranol T5651 (Asahi Kasei Chemicals Corporation polycarbonate diol: 1,5-pentanediol / 1,6-hexanediol, number average molecular weight of about 1000), Duranol T5652 (Asahi Kasei Chemicals Corporation polycarbonate diol) : 1,5-pentanediol / 1,6-hexanediol, number average molecular weight of about 2000). Kuraray polyol C-1015N is preferred.

  Examples of the method for synthesizing the polycarbonate diol include transesterification between a raw material diol and a carbonate, 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 formula (12), (13) or (14).

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

In General Formula (12), R ⁹ and R ¹⁰ each independently represent a divalent chain aliphatic group, a divalent cycloaliphatic group, or a divalent aromatic group, and a plurality of R ⁹ are These may be the same or different. n is an integer of 1 or more.

The divalent chain aliphatic group, divalent cycloaliphatic group or divalent aromatic group represented by R ⁹ and R ¹⁰ is a divalent group represented by R ⁸ in the general formula (11). And the same as the chain aliphatic group, divalent cycloaliphatic group or divalent aromatic group.
The divalent chain aliphatic group, divalent cycloaliphatic group or divalent aromatic group represented by R ⁹ and R ¹⁰ can be used alone or in combination of two or more.
m is a positive integer of 1 or more, preferably 2 or more, more preferably 3 or more, and still more preferably 4 or more. Moreover, although the upper limit of m is not specifically limited, Preferably it is 25 or less, More preferably, it is 20 or less, More preferably, it is 10 or less. If it is 25 or less, a heat resistant fall can be suppressed.

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

In General Formula (13), R ¹¹ represents a single bond, an alkylene group (—C _n H _2n —), a perfluoroalkylene group (—C _n F _2n —), an 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 to} X ⁸ each independently represent a hydrogen atom, a halogen atom, or an alkyl group, and may be the same as or different from each other.

  Although the upper limit of n in General formula (13) is not specifically limited, Preferably it is 10 or less, More preferably, it is 5 or less, More preferably, it is 3 or less.

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

The group having the structure represented by the general formula (13) is preferably a residue derived from a compound having one hydroxy group on each of the two benzene rings in the general formula (13).
Examples of the raw material for the divalent group having the structure represented by the general formula (13) include 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxydiphenyl sulfone, 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.
Preferred are 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxydiphenyl sulfone, 4,4 '-(9-fluorenylidene) diphenol or bisphenol A ethylene oxide adduct. More preferred is 4,4'-dihydroxydiphenyl ether or bisphenol A ethylene oxide adduct.
These compounds can be used individually or in combination of 2 or more types.
By using these raw materials, a diphenyl ether skeleton or the like can be introduced into the R ⁷ position of the general formula (11).

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

In General Formula (14), R ^{11 ′} is a single bond, an alkylene group (—C _n H _2n —), a perfluoroalkylene group (—C _n F _2n —), an 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 a fluorenylidene group. n is an integer of 1 or more. X ^{1 ′ to} X ^{8 ′} each independently represent a hydrogen atom, a halogen atom or an alkyl group, and may be the same as or different from each other.

  Although the upper limit of n in General formula (14) is not specifically limited, Preferably it is 10 or less, More preferably, it is 5 or less, More preferably, it is 3 or less.

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

The divalent group having a 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). As raw materials for the divalent group having the structure represented by the general formula (14), 4,4′-dihydroxydicyclohexyl ether, 4,4′-dihydroxydicyclohexylsulfone, hydrogenated bisphenol A, hydrogenated bisphenol F, water An ethylene oxide adduct of hydrogenated bisphenol A, a propylene oxide adduct of hydrogenated bisphenol A, or the like can be used.
Preferred is 4,4'-dihydroxydicyclohexyl ether or 4,4'-dihydroxydicyclohexyl sulfone.
These compounds can be used individually or in combination of 2 or more types.
By using these raw materials, a dicyclohexyl ether skeleton or the like can be introduced at the R ⁷ position of the general formula (11).

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

  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 cycloaliphatic group, or a divalent aromatic group.

As the divalent chain aliphatic group represented by R ¹² , the divalent cycloaliphatic group or the divalent aromatic group, the divalent chain formula represented by R ⁸ in the general formula (11) Examples thereof include the same as the aliphatic group, divalent cycloaliphatic group or divalent aromatic group, and R ⁸ in the general formula (11) and R ¹² in the general formula (15) are the same. Or different.

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

From the viewpoint of balance between heat resistance, flexibility, low hygroscopicity and the like, R ⁸ in the general formula (11) is preferably a divalent group having a structure represented by the following general formula (16). R ¹² in the general formula (15) is preferably a divalent group having a structure represented by the following general formula (17).

In General Formula (16), R ¹³ is a single bond, an alkylene group (—C _n H _2n —), a perfluoroalkylene group (—C _n F _2n —), an ether bond (—O—), an ester bond (— 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 each independently represent a hydrogen atom, a halogen atom or an alkyl group, and may be the same or different.

  N in the general formula (16) is an integer of 1 or more, preferably an integer of 1 to 10, more preferably an integer of 1 to 5, and further preferably an integer of 1 to 3. .

In the general formula (17), R ^{13 ′} represents a single bond, an alkylene group (—C _n H _2n —), a perfluoroalkylene group (—C _n F _2n —), an ether bond (—O—), an ester bond ( -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 ′} each independently represent a hydrogen atom, a halogen atom or an alkyl group, and may be the same or different.

  N in the general formula (17) is an integer of 1 or more, preferably an integer of 1 to 10, more preferably an integer of 1 to 5, and further preferably an integer of 1 to 3. .

In the general formula (11) and the general formula (15), a divalent chain aliphatic group, a divalent cycloaliphatic group or a divalent aromatic group is represented by the R ⁸ position of the general formula (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, by appropriately selecting a chain aliphatic diamine or a corresponding chain aliphatic diisocyanate, a cycloaliphatic diamine or a corresponding cycloaliphatic diisocyanate, an aromatic diamine or a corresponding aromatic diisocyanate, Polyesterimide having excellent properties, flexibility and low hygroscopicity can be obtained.
The diamine component of R ^{8 in the} general formula (11) and the diamine component of R ^{12 in} the general formula (15) or the corresponding diisocyanate component may be the same or different, but are preferably the same.

A diamine component having R ^{8 in the} general formula (11) and R ¹² in the general formula (15) as a basic skeleton or a diisocyanate component corresponding thereto will be described.

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

Examples of the cycloaliphatic diamine or the corresponding cycloaliphatic diisocyanate include trans-1,4-diaminocyclohexane, cis-1,4-diaminocyclohexane, 1,4-diaminocyclohexane (trans / cis). Mixture), 1,3-diaminocyclohexane, 4,4'-methylenebis (cyclohexylamine) (trans isomer, cis isomer, trans / cis mixture), isophorone diamine, 1,4-cyclohexane bis (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-diaminoadamantane, 4,4'-methylenebis (2-mes (Lucyclohexylamine), 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 the like.
Two or more of these can be used in combination.

Specific examples of the aromatic diamine or the corresponding aromatic diisocyanate include 2,2′-bis (trifluoromethyl) benzidine, p-phenylenediamine, m-phenylenediamine, and 2,4- Diaminotoluene, 2,5-diaminotoluene, 2,4-diaminoxylene, 2,4-diaminodurene, 4,4'-diaminodiphenylmethane, 4,4'-methylenebis (2-methylaniline), 4,4'- Methylene bis (2-ethylaniline), 4,4′-methylene bis (2,6-dimethylaniline), 4,4′-methylene bis (2,6-diethylaniline), 4,4′-diaminodiphenyl ether, 3,4 ′ -Diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, 2,4'-diamino Phenyl ether, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, 4,4'-diaminobenzophenone, 3,3'-diaminobenzophenone, 4,4'-diaminodiphenyl sulfide, 3,3 ' -Diaminodiphenyl sulfide, 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-tolidine, m-tolidine, 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 include safluoropropane, 2,2-bis (4-aminophenyl) hexafluoropropane, diaminoterphenyl, and the like.
Two or more of these can be used in combination.

From the standpoint of balance between heat resistance, flexibility, low hygroscopicity, and the like, a preferred component as the diamine component of R ⁸ of general formula (11) and R ¹² of 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-tolidine, diaminoterphenyl, 4,4'-methylenebis ( Cyclohexylamine), isophoronediamine and the like. More preferred are residues derived from 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether, 1,5-naphthalenediamine, o-tolidine, and even more preferred is 4,4'-diaminodiphenylmethane. 4,4'-diaminodiphenyl ether, a residue derived from o-tolidine, and most preferably a residue derived from 4,4'-diaminodiphenylmethane, o-tolidine.

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

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 are aggregated, and if it is larger than 100 nm, the transparency of the film is lowered.
For the average primary particle size, the particle itself is observed using a laser diffraction scattering method, a dynamic light scattering method, or an electron microscope, or a particle image appearing on the cross section or surface of the refractive index layer is observed using an electron microscope. Although it can be measured using a conventionally known method such as a method, for example, the particle diameter of 1000 arbitrary particles is measured by a laser diffraction scattering method defined in ISO 13320, and d ₁ , d ₂ , _{···, 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 When the volume per piece is v _i , the volume average particle diameter mv = average particle diameter weighted by the volume represented by {Σ (v _i · d _i )} / {Σ (v _i )} is calculated. can do.

  Content of a metal oxide particle is in the range of 20-70 mass% with respect to the total solid (100 mass%) in a polyimide film, Preferably it exists in the range of 30-50 mass%. 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 equipment load increases because the viscosity becomes too high during dope preparation. It 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, silicic acid. Fine particles such as aluminum, magnesium silicate, and calcium phosphate are included. Among these, it is preferable that silica is contained. This is because the refractive index of polyimide and silica is close and scattering is less likely to occur, so that transparency is easily obtained.

  As silica, a synthetic product or a commercially available product may be used. Examples of commercially available products include 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., and Nissan. Snowtex series (Snowtex OS, OXS, S, OS, 20, 30, 40, O, N, C, etc., Snowtex is a registered trademark) sold by Chemical Industry Co., Ltd. can be mentioned.

<Silane coupling agent>
The transparent polyimide film of the present invention contains a silane coupling agent.

As the silane coupling agent, a commercial product or a synthetic product may be used.
Examples of commercially available products include KBM series (KBM-1003, 303, 402, 1403, 502, 602, 903, etc.) and KBE series (KBE-1003, 402, 502) sold by Shin-Etsu Chemical Co., Ltd. , 903, 585, etc.), and those sold by Toray Dow Corning Co., Ltd. and Momentive Performance Material 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 the method for producing a reaction product of a polymerizable monomer and a reactive silane compound disclosed in JP-A-11-116240.

Specific examples of polymerizable monomers include (meth) acrylic acid, methyl (meth) acrylate, ethyl (meth) acrylate, (meth) acrylic acid-n-propyl, (meth) acrylic acid isopropyl, (meth)- n-butyl, isobutyl (meth) acrylate, (meth) acrylic acid-n-hexyl, (meth) acrylic acid cyclohexyl, (meth) acrylic acid-n-heptyl, (meth) acrylic acid-n-octyl, (meta ) -2-ethylhexyl acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, phenyl (meth) acrylate, toluyl (meth) acrylate, benzyl (meth) acrylate, (Meth) acrylic acid-2-methoxyethyl, (meth) acrylic acid-3-methoxybutyl, (meth) acrylic acid-2- Droxyethyl, 2-hydroxypropyl (meth) acrylate, stearyl (meth) acrylate, glycidyl (meth) acrylate, 2-aminoethyl (meth) acrylate, ethylene oxide adduct of (meth) acrylic acid, (meta ) Trifluoromethylmethyl acrylate, 2-trifluoromethylethyl (meth) acrylate, 2-perfluoroethylethyl (meth) acrylate, 2-perfluoroethyl-2-perfluorobutylethyl (meth) acrylate, (Meth) acrylic acid 2-perfluoroethyl, (meth) acrylic acid perfluoromethyl, (meth) acrylic acid diverfluoromethyl methyl, (meth) acrylic acid 2-perfluoromethyl-2-perfluoroethyl methyl, (meth) ) 2-perfluorohexylethyl acrylate, ( And (meth) acrylic acid monomers such as 2-perfluorodecylethyl acrylate and 2-perfluorohexadecylethyl methacrylate; styrene, vinyltoluene, α-methylstyrene, chlorostyrene, styrenesulfonic acid and the like Styrene monomers such as salts, fluorine-containing vinyl monomers such as perfluoroethylene, perfluoropropylene and vinylidene fluoride, silicon-containing vinyl monomers such as vinyltrimethoxysilane and vinyltriethoxysilane, maleic anhydride, maleic acid, malein Monoalkyl and dialkyl esters of acids, fumaric acid, monoalkyl and dialkyl esters of fumaric acid, maleimide, methylmaleimide, ethylmaleimide, propylmaleimide, butylmaleimide, hexylmale Nitrile group-containing vinyl monomers such as dode, octylmaleimide, dodecylmaleimide, stearylmaleimide, phenylmaleimide and cyclohexylmaleimide, amide group-containing vinyl monomers such as acrylamide and methacrylamide, vinyl acetate, vinyl propionate, vinyl pivalate, benzoate Vinyl esters such as vinyl acrylate and vinyl cinnamate, 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 tris Acrylate, pentaerythritol tetraacrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tetraacrylate, ditrimethylolpropante La (meth) acrylate, dipentaerythritol hexaacrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, isobutyl methacrylate, 2-ethylhexyl methacrylate, isodecyl methacrylate, n-lauryl acrylate, n-stearyl acrylate, 1,6 -Hexanediol dimethacrylate, perfluorooctylethyl methacrylate, trifluoroethyl methacrylate, urethane acrylate and the like, and mixtures thereof.
It is also possible to use a polymer (oligomer or prepolymer) 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) acryl means acryl or methacryl, and (meth) acrylate means acrylate or methacrylate.

  As the reactive silane compound, an organosilicon compound having a structure represented by the following general formula (A) is preferably used.

Formula (A)
X-R-Si (OR) ₃

  In general formula (A), R represents a C1-C10 organic group selected from a substituted or unsubstituted hydrocarbon group. X represents one or more functional groups selected from a (meth) acryloyl group, an epoxy group (glycid group), a urethane group, an amino group, and a fluoro group.

  Specific examples of the organosilicon compound having a structure represented by the general formula (A) include 3,3,3-trifluoropropyltrimethoxysilane, 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- Glycidoxyethoxy) propyltrimethoxysilane, γ- (meth) acrylooxy Tiltrimethoxysilane, γ- (meth) acrylooxymethyltriethoxysilane, γ- (meth) acrylooxyethyltrimethoxysilane, γ- (meth) acrylooxyethyltriethoxysilane, γ- (meth) acryl Rooxypropyltrimethoxysilane, γ- (meth) acrylooxypropyltrimethoxysilane, γ- (meth) acryloxypropyltriethoxysilane, γ- (meth) acryloxypropyltriethoxysilane, 3-ureidoisopropyl Propyltriethoxysilane, perfluorooctylethyltrimethoxysilane, perfluorooctylethyltriethoxysilane, perfluorooctylethyltriisopropoxysilane, trifluoropropyltrimethoxysilane, N-β (aminoethyl) γ-aminopropyl Chill dimethoxysilane, N-β (aminoethyl) .gamma.-aminopropyltrimethoxysilane, N- phenyl--γ- aminopropyltrimethoxysilane and mixtures thereof.

A polymeric silane coupling agent is synthesized by reacting a polymerizable monomer with a reactive silane compound.
As an example, an organic solvent solution in which a reactive silane compound is mixed within a range of 0.5 to 20 parts by mass and further within a 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. In this case, the total concentration of the polymerizable monomer and the reactive silane compound 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.

  As the polymerization initiator, azoisobutyl nitrile, lauroyl peroxide, benzoyl peroxide, di-t-butyl peroxide, t-butyl peroxy-2-ethylhexinoate, t-butyl peroxyisobutyrate, t- Peroxide polymerization initiators such as butyl peroxypivalate, t-butyl peroxybenzoate, t-butyl peroxyacetate, 2,2-azobisisobutyronitrile, 2,2-azobis (2,4-dimethyl) Azo compounds such as valeronitrile) and 2,2-azobis (4-methoxy-2,4-dimethylvaleronitrile).

  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 much time to synthesize a polymer silane coupling agent having a large molecular weight. On the other hand, if the reaction temperature is too high, the reaction rate is too high, and the desired reaction rate is too high. In some cases, the molecular weight cannot be controlled.

In addition, from the viewpoint of reducing the influence at the time of polyimide film formation by sufficiently slowing 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. .
Furthermore, the silane coupling agent preferably has at least one group selected from an acryl group, a methacryl group, an isocyanurate group, a phenyl group and a fluoro group from the viewpoint of the effect of the present invention.

  It is preferable that content of a silane coupling agent exists in the range of 0.01-5 mass parts with respect to 100 mass parts of metal oxide particles, and also in the range of 0.1-3 mass parts.

<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, as long as it has an aromatic ring in the molecule, and the matrix (main) part of the molecule has aromaticity. It does not have to be.

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

The aromatic compound is a compound having a molecular weight or a weight average molecular weight in the range of 300 to 10,000 and having an aromatic ring in the molecule. The molecular weight is used when the aromatic compound is a compound having a single structure, and the weight average molecular weight is used when the aromatic compound is an aggregate of compounds having a plurality of structures such as polymers and oligomers. When the molecular weight or the weight average molecular weight is less than 300, the volatile components are excessive when the polyimide film is produced, and the film itself is not easily produced. On the other hand, if the molecular weight or the weight average molecular weight is greater than 10,000, agglomerated foreign matter of the aromatic compound itself is generated so much that the film itself cannot be produced easily.
Accordingly, the fact that the molecular weight or weight average molecular weight of the aromatic compound is in the range of 300 to 10,000 is an indication that a polyimide film can be produced substantially.

  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 (Used by connecting three Showa Denko Co., Ltd.)
Column temperature: 25 ° C
Sample concentration: 0.1% by mass
Detector: RI Model 504 (GL Science Co., Ltd.)
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 10,000, 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 from the viewpoint of the effect of the present invention, and more preferably has four or more.

  It is preferable from a viewpoint of the effect of this invention that content of an aromatic compound exists in the range of 1-30 mass% in a polyimide film. It is more preferable to contain within the range of 15-30 mass% from a viewpoint with small retardation value Rt (nm) of a film thickness direction.

  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 the compatibility with the polyimide.

  Moreover, it is preferable from a viewpoint of the effect of this invention that it is a compound which has a fluorene structure in a molecule | numerator.

  Moreover, it is preferable from a viewpoint of the effect of this invention that it is a compound (it mentions later for details) which has a structure represented with the following general formula (III).

(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, wherein all or part of the hydroxy groups in the compound are esterified, and an aromatic ring is formed in the molecule. It is preferable that it is a compound which has.

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

In the general formula (I), R ^{14 to} R ²¹ each independently represents 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 in} 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). As a substituent which an alkyl group has, aryl groups, such as a phenyl group, are mentioned.

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

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

  Other sugar esters include compounds described in JP-A Nos. 62-42996 and 10-237084.

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

  As polyester which can be used for this invention, the polyester which has a structure represented by the following general formula (II) is more preferable from a compatible viewpoint.

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, p-tert-butylbenzoic acid, orthotoluic acid, metatoluic acid, p-toluic acid, and dimethylbenzoic acid. Examples include acids, ethyl benzoic acid, normal propyl benzoic acid, amino benzoic acid, acetoxy benzoic acid, aliphatic acids and the like, and these can be used as one kind or a mixture of two or more kinds.

  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, 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- Nthanediol, 2-ethyl-1,3-hexanediol, 2-methyl-1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-octadecanediol, etc. These glycols can be used as one kind or a mixture of two or more kinds.

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

  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, and tripropylene glycol. These glycols can be used as one kind or a mixture of two or more kinds.

  Examples of the alkylene dicarboxylic acid component having 4 to 12 carbon atoms of the polyester having the structure represented by the general formula (II) include succinic acid, maleic acid, fumaric acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, Dodecane dicarboxylic 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 aryl dicarboxylic acid component having 6 to 12 carbon atoms of the polyester having the structure represented by the general formula (II) include phthalic acid, terephthalic acid, isophthalic acid, 1,5-naphthalenedicarboxylic acid, and 1,4-naphthalenedicarboxylic acid. An acid etc. are mentioned.

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. .

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

(Aromatic compounds having an amide bond in the molecule)
The polyimide film of the present invention preferably 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, compounds described in paragraphs 0136 to 0138 of JP-A No. 2014-153444 can be used.

(Aromatic compounds having a fluorene structure in the molecule)
It is preferable from the viewpoint of the effect of the present invention that the polyimide film of the present invention contains an aromatic compound having a fluorene structure in the molecule.
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, compounds described in paragraphs 0048 to 0053 of JP-A No. 2014-218659 can be used.

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

In general formula (III), X represents a hetero atom or a carbon atom. Q represents an atomic group necessary for forming 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.

The aromatic heterocycle is generally an unsaturated heterocycle, preferably a heterocycle having the largest number of double bonds. The aromatic heterocycle is preferably a 5-membered ring, 6-membered ring or 7-membered ring, more preferably a 5-membered ring or 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 hetero ring 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-triazine ring. Among these, a 1,2,3-triazole ring, a 1,2,4-triazole ring, and a 1,3,5-triazine ring are more preferable.

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

Examples of the substituent that the aromatic heterocyclic ring may have and the substituent represented by R ^{22 to} R ²⁵ include a halogen atom (for example, a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom), an alkyl group (preferably Is an alkyl group having 1 to 30 carbon atoms, for example, methyl group, ethyl group, n-propyl group, isopropyl group, tert-butyl group, n-octyl group, 2-ethylhexyl group), cycloalkyl group (preferably A substituted or unsubstituted cycloalkyl group having 3 to 30 carbon atoms, for example, a cyclohexyl group, a cyclopentyl group, 4-n-dodecylcyclohexyl group), a bicycloalkyl group (preferably a substituted or unsubstituted group having 5 to 30 carbon atoms). 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] heptan-2-yl, bicyclo [2,2,2] octan-3-yl), an alkenyl group (preferably a substituted or unsubstituted alkenyl group having 2 to 30 carbon atoms) For example, a vinyl group), a cycloalkenyl group (preferably a substituted or unsubstituted cycloalkenyl group having 3 to 30 carbon atoms (a monovalent group obtained by removing one hydrogen atom of a cycloalkene having 3 to 30 carbon atoms). Yes, for example, 2-cyclopenten-1-yl, 2-cyclohexen-1-yl group), bicycloalkenyl group (substituted or unsubstituted bicycloalkenyl group, preferably substituted or unsubstituted bicycloalkenyl having 5 to 30 carbon atoms) Group (a monovalent group obtained by removing one hydrogen atom of a bicycloalkene having one double bond), for example, bicyclo [2,2,1] hept-2-ene-1 Yl group, bicyclo [2,2,2] oct-2-en-4-yl group), alkynyl group (preferably a substituted or unsubstituted alkynyl group having 2 to 30 carbon atoms, such as ethynyl group, propargyl group) Group), an aryl group (preferably a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, for example, a phenyl group, a p-tolyl group, a naphthyl group), a heterocyclic group (preferably a 5- or 6-membered substitution) Or a monovalent group obtained by removing one hydrogen atom from an unsubstituted aromatic or non-aromatic heterocyclic compound, more preferably a 5- or 6-membered aromatic heterocyclic group having 3 to 30 carbon atoms. For example, 2-furyl group, 2-thienyl group, 2-pyrimidinyl group, 2-benzothiazolyl group), cyano group, hydroxy group, nitro group, carboxy group, alkoxy group (preferably substituted or substituted with 1 to 30 carbon atoms). Is an unsubstituted alkoxy group, for example, methoxy group, ethoxy group, isopropoxy group, tert-butoxy group, n-octyloxy group, 2-methoxyethoxy group), aryloxy group (preferably having 6 to 30 carbon atoms). Substituted or unsubstituted aryloxy groups such as phenoxy group, 2-methylphenoxy group, 4-tert-butylphenoxy group, 3-nitrophenoxy group, 2-tetradecanoylaminophenoxy group), silyloxy group ( Preferred are silyloxy groups having 3 to 20 carbon atoms, such as trimethylsilyloxy group and tert-butyldimethylsilyloxy group), heterocyclic oxy groups (preferably substituted or unsubstituted heterocyclic oxy groups having 2 to 30 carbon atoms). 1-phenyltetrazole-5-oxy group, 2-tetrahydropyranyloxy Group), acyloxy group (preferably formyloxy group, substituted or unsubstituted alkylcarbonyloxy group having 2 to 30 carbon atoms, substituted or unsubstituted arylcarbonyloxy group having 6 to 30 carbon atoms, such as formyloxy Group, acetyloxy group, pivaloyloxy group, stearoyloxy group, benzoyloxy group, p-methoxyphenylcarbonyloxy group), carbamoyloxy group (preferably a substituted or unsubstituted carbamoyloxy group having 1 to 30 carbon atoms, N, N-dimethylcarbamoyloxy group, N, N-diethylcarbamoyloxy group, morpholinocarbonyloxy group, N, N-di-n-octylaminocarbonyloxy group, Nn-octylcarbamoyloxy group), alkoxycarbonyl Oxy group (preferably carbon 2-30 substituted or unsubstituted alkoxycarbonyloxy groups, such as methoxycarbonyloxy group, ethoxycarbonyloxy group, tert-butoxycarbonyloxy group, n-octylcarbonyloxy group), aryloxycarbonyloxy group (preferably A substituted or unsubstituted aryloxycarbonyloxy group having 7 to 30 carbon atoms, such as a phenoxycarbonyloxy group, p-methoxyphenoxycarbonyloxy group, pn-hexadecyloxyphenoxycarbonyloxy group), amino group ( Preferred are an amino group, a substituted or unsubstituted alkylamino group having 1 to 30 carbon atoms, and a substituted or unsubstituted anilino group having 6 to 30 carbon atoms, such as an amino group, a methylamino group, a dimethylamino group, and an anilino group. Group, N-methyl-anilino group A diphenylamino group), an acylamino group (preferably a formylamino group, a substituted or unsubstituted alkylcarbonylamino group having 1 to 30 carbon atoms, a 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 a substituted or unsubstituted aminocarbonylamino group having 1 to 30 carbon atoms such as carbamoylamino group, N, N-dimethylaminocarbonylamino group, N, N-diethylaminocarbonylamino group, morpholinocarbonylamino group), alkoxycarbonylamino group (preferably a substituted or unsubstituted alkoxycarbonylamino group having 2 to 30 carbon atoms, , Methoxycal Nylamino group, ethoxycarbonylamino group, tert-butoxycarbonylamino group, n-octadecyloxycarbonylamino group, N-methyl-methoxycarbonylamino group), aryloxycarbonylamino group (preferably having 7 to 30 carbon atoms) Substituted aryloxycarbonylamino group, for example, phenoxycarbonylamino group, p-chlorophenoxycarbonylamino group, mn-octyloxyphenoxycarbonylamino group), sulfamoylamino group (preferably having 0 to 30 carbon atoms) Substituted or unsubstituted sulfamoylamino groups such as sulfamoylamino group, N, N-dimethylaminosulfonylamino group, Nn-octylaminosulfonylamino group), alkyl and arylsulfonylamino groups Preferred are substituted or unsubstituted alkylsulfonylamino having 1 to 30 carbon atoms and substituted or unsubstituted arylsulfonylamino groups having 6 to 30 carbon atoms, such as methylsulfonylamino group, butylsulfonylamino group, phenylsulfonylamino Group, 2,3,5-trichlorophenylsulfonylamino group, p-methylphenylsulfonylamino group), mercapto group, alkylthio group (preferably a substituted or unsubstituted alkylthio group having 1 to 30 carbon atoms, for example, methylthio Group, ethylthio group, n-hexadecylthio group), arylthio group (preferably a substituted or unsubstituted arylthio group having 6 to 30 carbon atoms, such as phenylthio group, p-chlorophenylthio group, m-methoxyphenylthio group) A heterocyclic thio group (preferably having 2 to 3 carbon atoms) 0 substituted or unsubstituted heterocyclic thio group, for example, 2-benzothiazolylthio group, 1-phenyltetrazol-5-ylthio group), sulfamoyl group (preferably a substituted or unsubstituted group having 0 to 30 carbon atoms) For example, N-ethylsulfamoyl group, N- (3-dodecyloxypropyl) sulfamoyl group, N, N-dimethylsulfamoyl group, N-acetylsulfamoyl group, N-benzoylsulfur group Famoyl group, N- (N′phenylcarbamoyl) sulfamoyl group), sulfo group, alkyl and arylsulfinyl group (preferably substituted or unsubstituted alkylsulfinyl group having 1 to 30 carbon atoms, substituted or unsubstituted 6 to 30 carbon atoms) Arylsulfinyl group of, for example, methylsulfinyl group, ethylsulfinyl group, A rusulfinyl group, a p-methylphenylsulfinyl group), an alkyl and an arylsulfonyl group (preferably a substituted or unsubstituted alkylsulfonyl group having 1 to 30 carbon atoms, a substituted or unsubstituted arylsulfonyl group having 6 to 30 carbon atoms, For example, methylsulfonyl group, ethylsulfonyl group, phenylsulfonyl group, p-methylphenylsulfonyl group), acyl group (preferably formyl group, substituted or unsubstituted alkylcarbonyl group having 2 to 30 carbon atoms, 7 to 30 carbon atoms) A substituted or unsubstituted arylcarbonyl group, for example, an acetyl group, a pivaloylbenzoyl group), an aryloxycarbonyl group (preferably a substituted or unsubstituted aryloxycarbonyl group having 7 to 30 carbon atoms, , Phenoxycarbonyl group, o-chlorophenoxycarbo Group, m-nitrophenoxycarbonyl group, p-tert-butylphenoxycarbonyl group), alkoxycarbonyl group (preferably a substituted or unsubstituted alkoxycarbonyl group having 2 to 30 carbon atoms, such as methoxycarbonyl group, ethoxycarbonyl Group, tert-butoxycarbonyl group, n-octadecyloxycarbonyl group), carbamoyl group (preferably a substituted or unsubstituted carbamoyl group having 1 to 30 carbon atoms, such as carbamoyl group, N-methylcarbamoyl group, N, N-dimethylcarbamoyl group, N, N-di-n-octylcarbamoyl group, N- (methylsulfonyl) carbamoyl group), aryl and heterocyclic azo group (preferably a substituted or unsubstituted arylazo group having 6 to 30 carbon atoms) , Substituted or unsubstituted C 3-30 carbon atoms A terocyclic 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) ), A phosphino group (preferably a substituted or unsubstituted phosphino group having 2 to 30 carbon atoms, such as dimethylphosphino group, diphenylphosphino group, methylphenoxyphosphino group), phosphinyl group (preferably 2 carbon atoms) A substituted or unsubstituted phosphinyl group having ˜30, for example, a phosphinyl group, a dioctyloxyphosphinyl group, a diethoxyphosphinyl group), a phosphinyloxy group (preferably a substituted or unsubstituted group having 2 to 30 carbon atoms). Substituted phosphinyloxy groups such as diphenoxyphosphinyloxy group, dioctyl Xyphosphinyloxy group), phosphinylamino group (preferably substituted or unsubstituted phosphinylamino group having 2 to 30 carbon atoms, such as dimethoxyphosphinylamino group, dimethylaminophosphinylamino group) Group) and a silyl group (preferably a substituted or unsubstituted silyl group having 3 to 30 carbon atoms, such as a trimethylsilyl group, a tert-butyldimethylsilyl group, and a phenyldimethylsilyl group).

  In the compound having the structure represented by the general formula (III), the aromatic heterocycle represented by Q is preferably a 1,2,3-triazole ring, and the structure represented by the following general formula (IV) More preferred is a benzotriazole-based compound having

In the 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, or a carbon number. It represents a phenyl group or a phenylalkyl group having 7 to 15 phenylalkyl groups, phenyl groups, or 1 to 4 alkyl groups having 1 to 4 carbon atoms as substituents.

E ¹ represents a phenylalkyl group having 7 to 15 carbon atoms, a phenyl group, or a phenyl group or phenylalkyl 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, or a carbon number. A 7-15 phenylalkyl group, a phenyl group, or a phenyl group having 1 to 3 alkyl groups having 1 to 4 carbon atoms as a substituent or a phenylalkyl group is represented.
Alternatively, E ² represents at least one —OH group, —OCOE ⁵ group, —OE ⁴ group, —NCO group, —NH ₂ group, —NHCOE ⁵ group, —NHE ⁴ group or —N (E ^{4) as a} substituent. ) An alkyl group having 1 to 24 carbon atoms or an alkenyl group having 2 to 18 carbon atoms having _two groups or a combination thereof.
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 represents a -NH ₂ group, or an alkyl group or an alkenyl group having 2 to 18 carbon atoms having 1 to 24 carbon atoms having a group composed of a combination of them.
E ⁴ represents a linear or branched alkyl group having 1 to 24 carbon atoms.
E ⁵ represents a hydrogen atom, a linear or branched alkylene group having 1 to 18 carbon atoms, a cycloalkyl group having 5 to 12 carbon atoms, or 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, or a phenylalkyl having 7 to 15 carbon atoms. Group, an aryl group having 6 to 10 carbon atoms, an aryl group having 1 or 2 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 consists of 6 to 16 carbon atoms).

Alternatively, in general formula (2), G ¹ represents a hydrogen atom, G ² represents a chlorine atom, a fluorine atom, a —CF ₃ group, a —SOE ³ group, or a —SO ₂ E ³ group, 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 group having 1 to 7 carbon atoms. It is a benzotriazole compound having a structure represented by a chain alkyl group.

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

  Hereinafter, preferred benzotriazole compounds (Exemplary Compounds 1 to 6) suitable for the present invention will be shown, but the present invention is not limited thereto.

  Of the benzotriazole compounds, the most preferred compound is Exemplified Compound 1.

  Moreover, it is preferable that the compound which has a structure represented by general formula (III) is a compound which has a structure represented by the following general formula (V).

In 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, or an aryl having 6 to 18 carbon atoms. 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 have a hydroxy group, a halogen atom, an alkyl group having 1 to 12 carbon atoms, or 1 to 12 carbon atoms as a substituent. May be linked by 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 or an alkenyl group having 3 to 8 carbon atoms of 1 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 —O—R ²⁶ .

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

As a C3-C8 cycloalkyl group represented by R < ²⁶ > of general formula (V), a cyclopropyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group etc. are mentioned, for example.

Examples of the alkenyl group having 3 to 8 carbon atoms represented by R ²⁶ in the general formula (V) include unsaturated linear or branched propenyl group, butenyl group, pentenyl group, hexenyl group, heptenyl group, and octenyl group. It is mentioned regardless of the position of the bond.

Examples of the aryl group having 6 to 18 carbon atoms or the alkylaryl group having 7 to 18 carbon atoms represented by R ²⁶ in the general formula (V) include a phenyl group, a naphthyl group, a 2-methylphenyl group, and 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-amyl A phenyl group, 2,5-di-tert-octylphenyl group, biphenyl group, 2,4,5-trimethylphenyl group and the like can be mentioned.

Examples of the arylalkyl group having 7 to 18 carbon atoms represented by R ²⁶ in the general formula (V) include a benzyl group, a phenethyl group, a 2-phenylpropan-2-yl group, and a diphenylmethyl group.

Examples of the alkyl group having 1 to 8 carbon atoms represented by R ²⁷ in the general formula (V) include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a sec-dibutyl group, a tert-butyl group, An isobutyl group, an amyl group, a tert-amyl group, an octyl group, a tert-octyl group and the like can be mentioned. Among them, a methyl group is preferable because of its excellent ultraviolet absorption ability.

The alkenyl group having 3 to 8 carbon atoms represented by R ²⁷ in the general formula (V), those similar to the alkenyl group having 3 to 8 carbon atoms represented by R ²⁶ in the general formula (V) .

  Hereinafter, although the triazine type compound (Exemplary compounds 7 to 17) represented by the general formula (V) is shown, it is not limited thereto.

  In this invention, the compound which has a structure represented by general formula (III) can be used individually by 1 type or in combination of 2 or more types.

  The molecular weight of the compound having a 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. Within range. If it exists in the range of 100-800, generation | occurrence | production of precipitation and bleed-out of compound itself can be suppressed, and a compound can be disperse | distributed uniformly within dope.

  The compound having the structure represented by the general formula (III) can be added by dissolving 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. To the dope or directly into the dope composition. 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 effects of the present invention are achieved, but 2 to 20% by mass with respect to polyimide from the viewpoint of preventing bleeding out and precipitation. The range of 3-10 mass% is still more preferable.

<Other additives>
(Inorganic filler)
The polyimide film of the present invention can be mixed with an inorganic filler as long as the effects of the present invention are not impaired.
As the inorganic filler, it is preferable to use inorganic compound particles. As inorganic compound particles, 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, Examples thereof include calcium phosphate. As the inorganic compound particles, those containing silicon are preferable from the viewpoint of low turbidity, 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 of 0.05 to 0.3 μm. If the particles have an average particle size of 80 to 400 nm, 1 It is also preferable that it is contained as secondary particles.

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 film having a multilayer structure by the co-casting method, it is preferable to contain particles of this addition amount on the surface.

  Silicon dioxide particles are commercially available, for example, under the trade names Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600 (above, Nippon Aerosil Co., Ltd.). Can do.

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

  Examples of the resin particles include silicone resin, fluorine resin, and acrylic resin. Among them, 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 (above, 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 reducing the friction coefficient while keeping the haze of the film low.

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

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

  For example, 5-chloro-2- (3,5-di-sec-butyl-2-hydroxylphenyl) -2H-benzotriazole, (2-2H-benzotriazol-2-yl) -6- (linear or side Chain dodecyl) -4-methylphenol, 2-hydroxy-4-benzyloxybenzophenone, 2,4-benzyloxybenzophenone, etc., and tinuvin 109, tinuvin 171, tinuvin 234, tinuvin 326, tinuvin 327, tinuvin 328, There are tinuvins such as tinuvin 928, and these are all commercial products manufactured by BASF Japan Ltd. and can be preferably used. Among these, halogen-free ones are preferable.

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

  It is preferable that the polyimide film of this invention contains 2 or more types of ultraviolet absorbers.

  As the UV absorber, a polymer UV absorber can be preferably used, and in particular, a polymer type UV 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 UV absorber is to add the dope after dissolving the UV absorber in an alcohol such as methanol, ethanol, butanol, an organic solvent such as dichloromethane, methyl acetate, acetone, dioxolane, or a mixed solvent thereof, or You may add directly in dope composition.

  For an inorganic powder that does not dissolve in an organic solvent, a dissolver or a sand mill is used in the organic solvent and the polyimide film to be dispersed and then added to the dope.

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

(Antioxidant)
Antioxidants are also referred to as deterioration inhibitors.
When an electronic device or the like is placed in a high humidity and high temperature state, the polyimide film may be deteriorated.
Since the antioxidant has a role of delaying or preventing the polyimide film from being decomposed by, for example, halogen in the residual solvent in the polyimide film or phosphoric acid of the phosphoric acid plasticizer, the polyimide film of the present invention is used. It is preferable to make it contain in.

As such an antioxidant, a hindered phenol compound is preferably used. For example, 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], 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-tert-butyl-4-hydroxyphenyl) propionate], octa Sil-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-hydroxy Benzyl) -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, hydrazine-based metal deactivators such as N, N′-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyl] hydrazine and tris (2,4-di- A phosphorus 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 in the range of 10 to 1000 ppm by mass ratio with respect to the polyimide film.

(Peeling accelerator)
As additives for reducing the peeling resistance of the polyimide film, there are many that have a remarkable effect on surfactants, and preferred release agents include phosphate ester type surfactants, carboxylic acid or carboxylate type surfactants. A sulfonic acid or sulfonate surfactant and a sulfate ester surfactant are effective. A fluorine-based surfactant in which part of the hydrogen atoms bonded to the hydrocarbon chain of the surfactant is substituted with fluorine atoms is also effective. Examples of the release agent are given below.

_{RZ-1: C 8 H 17} O-P (= O) - (OH) 2
_{RZ-2: C 12 H 25} O-P (= O) - (OK) 2
_{RZ-3: C 12 H 25} OCH 2 CH 2 O-P (= O) - (OK) 2
_{RZ-4: C 15 H 31} (OCH 2 CH 2) 5 O-P (= 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 O-P (= 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 triisopropyl naphthalene sulfonate RZ-16: Sodium tri-t-butyl naphthalene sulfonate 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 addition amount of the peeling accelerator 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 polyimide (100 parts by mass). It is most preferably within the range of 5 parts by mass.

  In addition, the additive contained in the polyimide film of the present invention is not limited to the above.

<Production method of polyimide film>
Below, the specific example of the manufacturing method of the polyimide film of this invention is demonstrated. In addition, the following form is a preferable form and this invention is not limited to this.

A method for producing a polyimide film includes a step of dissolving a 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. The step of forming a film (casting step), the step of evaporating the solvent from the cast film on the support (solvent evaporation step), the step of peeling the cast film from the support (peeling step), and the obtained film Step of drying (first drying step), step of stretching the film (stretching step), step of further drying the stretched film (second drying step), step of winding up the obtained polyimide film (winding step) including.
In addition, when using a polyamic acid instead of a polyimide, it is preferable to further have the process (heating process) etc. which heat-process the film after the said extending | stretching, and imidize.

Further, in the method for producing the transparent polyimide film of the present invention, the standard deviation σ of the gray value in the 8-bit gray scale in a predetermined rectangular area cut out from the projected image of the transparent polyimide film is in the range of 0.50 to 1.10. The black area occupying area ratio in the binarized image of the rectangular area is adjusted to 50% or less to suppress the occurrence of unevenness in the projected image when observed through a point light source.
As specific achievement means, the following methods (i) to (iii) may be mentioned.

(I) The reaction rate of dehydration condensation when the metal oxide particles are connected via a silane coupling agent is controlled.
For example, a silane coupling agent having a slow reaction rate is selected so that water generated gradually after the film is cured is removed. Since the reaction rate is often accelerated when the pH in the dope touches 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) The water generated before the phase separation between the polyimide and the solvent is allowed to escape.
As a means for achieving this, an additive having aromaticity such as an aromatic compound as described above is added. Since the compound having aromaticity has high hydrophobicity, it repels water and the water is quickly removed.
The other is a method in which an azeotropic dehydrating agent that is miscible with water is added, the vaporization of the azeotropic dehydrating agent is stopped, and water is quickly removed.

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

  Hereinafter, each process of the manufacturing method of the polyimide film which concerns on this form is demonstrated.

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

Any solvent may be used 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, tetramethylene sulfone, dimethyl sulfoxide, m-cresol, phenol, p-chlorophenol, 2-chloro-4-hydroxytoluene, diglyme, triglyme, te Raguraimu, dioxane, .gamma.-butyrolactone, dioxolane, cyclopentanone, epsilon-caprolactam and chloroform.
In addition to these solvents, a poor solvent such as hexane, heptane, benzene, toluene, xylene, chlorobenzene, or o-dichlorobenzene may be used to such an extent that the polyimide and the additive according to the present invention do not precipitate.

  Alcohol solvents can also be used, such as 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 include pentafluoro-1-propanol, nitroethane, methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol, and tert-butanol. Especially, it is preferable to select from methanol, ethanol, and butanol from a viewpoint which improves peelability and enables high-speed casting, and it is more preferable to use methanol or ethanol. When the ratio of the alcohol in the dope increases, the web gels and peeling from the metal support becomes easy.

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

In order to azeotropically dehydrate water generated when the metal oxide particles and the silane coupling agent undergo dehydration condensation in the film drying step, an azeotropic dehydrating agent may be added in advance in the dope adjustment step.
Examples of the azeotropic dehydrating agent include aromatic hydrocarbons such as toluene, xylene, and solvent naphtha, and alicyclic hydrocarbons such as cyclohexane, methylcyclohexane, and dimethylcyclohexane.
When using an azeotropic dehydrating agent, the addition amount is about 1 to 30% by mass in the total amount of organic solvent.

  For dissolving 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 under pressure above the boiling point of the main solvent, JP-A-9-95544 Various dissolution methods such as a method performed by the cooling dissolution method described in JP-A-9-95557 or JP-A-9-95538 and a method performed at high pressure described in JP-A-11-21379 are used. be able to.

  The prepared dope may be guided to a filter by a liquid feed pump or the like and filtered. As a filter medium used for filtration, a metal fired filter, a metal nonwoven fabric filter, a cotton cloth filter, a paper filter, or the like can be used as appropriate. Moreover, you may filter separately before adding dope and a metal oxide particle, and may filter after adding. 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 the boiling point at 1 atm of the dichloromethane + 5 ° C. or more. Can do. A preferred temperature range is 45 to 120 ° C, more preferably 45 to 70 ° C, and still more preferably 45 to 55 ° C.

In many cases, the main dope may contain a recycle material in the range of 10 to 50% by mass. Return material refers to a part that is reused as a raw material for some reason, for example, a product obtained by finely pulverizing a polyimide film, where both sides of the film are cut off. A polyimide film raw material or the like exceeding the specified value of the film due to an object or an abrasion is used.
Moreover, as a raw material of resin used for dope preparation, what pelletized a polyimide, another compound, etc. previously can also be used.

(Casting film forming process)
In the cast film forming step, the dope (main dope) prepared in the dope preparing step is cast on a support to form a cast film. For example, an endless support that feeds the dope to a die through a feed pump (for example, a pressurized metering gear pump) and moves it infinitely, such as a casting position on a metal support such as a stainless steel belt or a rotating metal drum The dope is cast from a die (for example, an endless belt casting apparatus).
The metal support in casting (casting) is preferably a mirror-finished surface. The support is a metal support such as a stainless steel belt, a drum whose surface is plated with a casting, a stainless steel belt, or a stainless steel belt. Preferably used. The cast width can be in the range of 1 to 4 m, preferably in the range of 1.5 to 3 m, and more preferably in the range of 2 to 2.8 m.

  The support may not 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 made of polytetrafluoroethylene or the like can be used. When using a polyimide as a flexible substrate, you may wind up a polyimide with the metal support body which cast the polyimide.

  The running speed of the metal support is not particularly limited, but is usually 5 m / min or more, preferably 10 to 180 m / min, particularly preferably 80 to 150 m / min. As the traveling speed of the metal support increases, the accompanying gas is more likely to be generated, and the occurrence of film thickness unevenness due to the 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 speed of the cast film can be increased. However, if the temperature is too high, the cast film may foam or the flatness may deteriorate. It is preferable to carry out within a temperature range of −50 to −10 ° C. relative to the boiling point of the solvent.

The die has a shape that becomes gradually narrower toward the discharge port in a vertical cross section with respect to the width direction. In general, the die usually has tapered surfaces on the downstream side and the upstream side in the lower traveling direction, and a discharge port is formed in a slit shape between the tapered surfaces. A die made of metal is preferably used, and specific examples include stainless steel, titanium, and the like. In the present invention, when manufacturing 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. Examples of the pressure die include a coat hanger die and a T die, and any of them is preferably used. Even when films with different thicknesses are continuously manufactured, the discharge rate of the dies is maintained at a substantially constant value. Therefore, when a pressure die is used, conditions such as extrusion pressure and shear rate are also substantially reduced. Maintained at a constant value. In order to increase the film forming speed, two or more pressure dies may be provided on the metal support, and the dope amount may be divided and laminated.

(Solvent evaporation process)
In the solvent evaporation step, the solvent is evaporated from the cast film on the support. That is, this step is a pre-drying step that is performed on a metal support and the cast film is heated on the metal support to evaporate the solvent.
In order to evaporate the solvent, for example, a method of blowing heated air from the casting membrane side and the back side of the metal support by a dryer, a method of transferring heat from the back side of the metal support by a heating liquid, a method of transferring heat from the front and back by radiant heat Etc. 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 be different 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 cast film until the residual solvent amount is in the range of 10 to 150% by mass from the viewpoint of the peelability of the cast film and the transportability after peeling. In the present invention, the residual solvent amount is represented by the following mathematical formula (3).

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

  In the above mathematical formula (3), M is the mass of the casting membrane (film) at a predetermined time. N is the mass when M is dried 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 having the solvent 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. However, if wrinkles are likely to occur during peeling, peeling is performed with a tension of 190 N / m or less. It 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 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 conveyance in the stretching step, it is preferable that the film is sequentially sent to the first drying step and the stretching step after the peeling step.

(First drying step)
The first drying step is a drying step in which the film is heated and the solvent is further evaporated. The drying means is not particularly limited, and for example, hot air, infrared rays, a heating roller, microwaves and the like can be used. From the viewpoint of simplicity, it is preferable to dry with hot air or the like while transporting the film with rollers arranged in a staggered manner. The drying temperature is preferably in the range of 30 to 200 ° C. in consideration of the residual solvent amount and the stretching ratio in transportation.

(Stretching process)
In the stretching step, the film is stretched. Thus, the film thickness, flatness, orientation, etc. of the film can be controlled by stretching the film peeled from the metal support.
In the manufacturing method which concerns on this form, it extends | stretches in a longitudinal direction and / or a lateral direction. The stretching operation may be performed in multiple stages. When biaxial stretching is performed, simultaneous biaxial stretching may be performed or may be performed stepwise. In this case, stepwise means that, for example, 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 one of the stages. Is also possible.

That is, for example, the following stretching steps are possible.
-Stretch in longitudinal direction-> Stretch in width direction-> Stretch in longitudinal direction-> Stretch in longitudinal direction-Stretch in width direction-> Stretch in width direction-> Stretch in longitudinal direction-> Stretch in longitudinal direction

  Simultaneous biaxial stretching includes stretching in one direction and contracting the other while 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. If the amount of the residual solvent is within the above range, the effect of improving the flatness by stretching can be obtained, and sufficient film strength can be obtained.

  In the manufacturing method according to this 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 in a desired range. It is preferable to extend | stretch in the temperature range of (Tg-200)-(Tg + 100) degreeC with respect to the glass transition temperature (Tg) of a film. If it extends in the said temperature range, since a extending | stretching stress can be reduced, haze will become low. Moreover, generation | occurrence | production of a fracture | rupture is suppressed and the polyimide film excellent in planarity and the coloring property of the film itself is obtained. The stretching temperature is more preferably in the temperature range of (Tg−150) to (Tg + 50) ° C. In addition, you may perform this process at the same process as the 1st drying process (at the same time).

In the manufacturing method according to the present embodiment, the film having self-supporting property peeled from the support can be stretched in the longitudinal direction by regulating the running speed with a stretching roller.
In order to stretch the film in the width direction, for example, the entire width of the film is held with clips or pins in the width direction for the entire drying process or a part of the process as disclosed in JP-A-62-46625. A method of drying while drying (referred to as a tenter method), among which a tenter method using a clip is preferably used. The film stretched in the longitudinal direction or the unstretched film is preferably introduced into the tenter in a state where both ends in the width direction are gripped by the clip, and stretched in the width direction while running with the clip type tenter.

  In stretching in the width direction, stretching in the width direction of the film at a stretching speed in the range of 50 to 1000% / min is preferable from the viewpoint of improving the flatness of the film. If the stretching speed is 50% / min or more, the planarity is improved and the film can be processed at a high speed, which is preferable from the viewpoint of production aptitude, and if it is within 1000% / min, the film is broken. Can be processed without any problem. A more preferable stretching speed is in the range of 100 to 500% / min. The stretching speed is defined by the following mathematical formula (4).

Formula (4)
Stretching speed (% / min) = {(d ₁ / d ₂ ) −1} × 100 (%) / t

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

  In the stretching step, usually, after stretching, holding and relaxation are performed. That is, in this step, it is preferable to perform a stretching step for stretching the film, a holding step for holding the film in a stretched state, and a relaxation step for relaxing the film in the stretched direction in this order. In the holding step, the drawing at the draw ratio achieved in the drawing step is held at the drawing temperature in the drawing step. In the relaxation stage, the stretching in the stretching stage is held in the holding stage, and then the stretching is relaxed by releasing the tension for stretching. The relaxation stage may be performed at a temperature lower than the stretching temperature in the stretching stage.

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

  Moreover, as a heat drying means, it is not restricted to a hot air, For example, infrared rays, a heating roller, a microwave etc. can be used. From the viewpoint of simplicity, it is preferable to dry with hot air or the like while transporting the film with rollers arranged in a staggered manner. The drying temperature is preferably in the range of 40 to 350 ° C. in consideration of the residual solvent amount, the stretching ratio in transportation, and the like.

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

(Winding process)
In the winding process, the film obtained above is wound. Preferably, in the winding step, the obtained film is wound and then cooled to room temperature. The winding machine may be a commonly 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 for example, it is preferably in the range of 1 to 200 μm, particularly in the range of 10 to 100 μm.

In the winding process, both ends of the film sandwiched between clip-type tenters (tenter clips) when stretched and conveyed may be slit. The slit film end is preferably cut into a width of 1 to 30 mm, then dissolved in a solvent and reused as a recycled material.
The ratio of the portion reused as a recycled material in the formed film is preferably 10 to 90% by mass, more preferably 20 to 80% by mass, and still more preferably 30 to 70% by mass.
The input amount varies slightly depending on the amount of the recycled material generated during the film forming process or finally, but the mixing ratio of the recycled material with respect to the total solid content in the dope is usually about 10 to 50% by mass, preferably 15 About 40% by mass. The mixing ratio of the recycled materials is preferably as constant as possible for production stability.

  Each of the steps from the solvent evaporation step to the winding step described above may be performed in an air atmosphere or an inert gas atmosphere such as nitrogen gas. Moreover, it is preferable to perform each process, especially a drying process and an extending | stretching process in consideration of the explosion limit concentration of the solvent in atmosphere.

(Heating process)
As described above, when using polyamic acid instead of polyimide, it is preferable to imidize the film after stretching by heat treatment. Specifically, after the winding step, heating to further heat-treat the film dried in the second drying step in order to improve imidization in the polymer chain molecules and between the polymer chain molecules to improve mechanical properties. Perform the process.
Moreover, even when the dope is prepared using polyimide (imidation rate 100%) or when the imidation rate of the film becomes 100% by performing the second drying step, the residual stress of the film A heating process is performed for the purpose of relaxing the above. In addition, the said 2nd drying process may serve as a heating process.

A heating means is performed using well-known means, such as a hot air, an electric heater, and a microwave, for example. As the electric heater, the above-described infrared heater can be used.
It is preferable that the heat treatment conditions are appropriately performed within a temperature range of 200 to 450 ° C. and within a range of 30 seconds to 1 hour. Thereby, the dimensional stability of a polyimide film can be improved. In the heating step, if the film is heated rapidly, defects such as an increase in surface defects occur, and therefore it is preferable to select the heating method as appropriate. The heating step is preferably performed in a low oxygen atmosphere.
When the heating temperature in the second drying step and the heating step exceeds 450 ° C., the energy required for heating becomes very large, which increases the manufacturing cost and further increases the environmental load. Therefore, the heating temperature is 450 ° C. The following is preferable.
In addition, after the winding process, before or after the heating process, a process of slitting the width direction end of the polyimide film, or a process of neutralizing the polyimide film if charged, etc. It is good.

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

  Regarding the outline of the organic EL element applicable to the organic EL display of the present invention, for example, JP2013-157634A, JP2013-168552A, JP2013-177361A, JP2013-187221A. JP, 2013-191644, JP 2013-191804, JP 2013-225678, JP 2013-235994, JP 2013-243234, JP 2013-243236, JP 2013-242366 A, JP 2013-243371 A, JP 2013-245179 A, JP 2014-003249 A, JP 2014-003299 A, JP 2014-013910 A, JP Japanese Laid-Open Patent Publication No. 2014-017493, JP It can be mentioned arrangement described in -017494 Patent Publication.

  Moreover, when using the polyimide film of this invention as a front plate of a flexible display, you may further have a well-known various functional layer applicable to a front plate. As a functional layer, the layer which has functions, such as ultraviolet absorption, surface hardness, adhesiveness, hue adjustment, refractive index adjustment, is mentioned, for example.

  EXAMPLES 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>
To a 4-necked flask equipped with a dry nitrogen gas inlet tube, a condenser, a Dean-Stark aggregator filled with toluene, and a stirrer, 2,2-bis (3,4-dicarboxyphenyl) -1,1,1, 25,59 g (57.6 mmol) of 3,3,3-hexafluoropropane dianhydride (anhydride A) (manufactured by Daikin Industries) was added to N, N-dimethylacetamide (DMAc) (134 g), and a nitrogen stream Under stirring at room temperature.

  To this was added 19.2 g (60 mmol) of 4,4′-diamino-2,2′-bis (trifluoromethyl) biphenyl (diamine A) (manufactured by Daikin Industries, Ltd.), and the mixture was heated and stirred at 80 ° C. for 6 hours. Thereafter, the external temperature was heated to 190 ° C., and water generated along with imidization was distilled off azeotropically with toluene. When heating, refluxing, and stirring were continued for 6 hours, generation of water was not observed. Subsequently, the mixture was heated for 7 hours while distilling off toluene. Further, after distilling off toluene, methanol was added for reprecipitation, and after drying the solid content, a 20% by mass N, N-dimethylacetamide solution was prepared to prepare polyimide solution A. .

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

  To this was added 11.5 g (60 mmol) of 2,5-diethyl-4,6-dimethylbenzene-1,3-diamine (diamine B) (manufactured by Daikin Industries), and the mixture was heated and stirred at 80 ° C. for 6 hours. Thereafter, the external temperature was heated to 190 ° C., and water generated along with imidization was distilled off azeotropically with toluene. When heating, refluxing, and stirring were continued for 6 hours, generation of water was not observed. Subsequently, the mixture was heated for 7 hours while distilling off toluene. Further, after distilling off toluene, methanol was added for reprecipitation, and after drying the solid content, a 20% by mass N, N-dimethylacetamide solution was prepared to prepare polyimide solution B. .

<Preparation of polyimide solution C>
A bicyclo [2.2.2] oct-7-ene-2,3,5,6 was added to a four-necked flask equipped with a dry nitrogen gas inlet tube, a condenser, a Dean-Stark aggregator filled with toluene, and a stirrer. -Tetracarboxylic acid 2,3: 5,6-dianhydride (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 Under stirring at room temperature.

  To this, 12.4 g (30 mmol) of 4,4 ′-[isopropylidenebis [(4,1-phenylene) oxy]] bisaniline (diamine C) (produced by Daikin Industries) and 4,4 ′-[(4 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. Thereafter, the external temperature was heated to 190 ° C., and water generated along with imidization was distilled off azeotropically with toluene. When heating, refluxing, and stirring were continued for 6 hours, generation of water was not observed. Subsequently, the mixture was heated for 7 hours while distilling off toluene. Further, after distilling off toluene, methanol was added for reprecipitation, and after drying the solid content, a 20% by mass N, N-dimethylacetamide solution was prepared to prepare polyimide solution C. .

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

<Preparation of metal oxide particle dispersion A>
100 g of 20% by weight silica sol gel aqueous solution (spherical, particle size 20 nm), 80 g of isopropanol, 80 g of N, N-dimethylacetamide were put into 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 of silica particles.

<Preparation of metal oxide particle dispersions B and C>
In the preparation of the metal oxide particle dispersion A, the silica sol gel was similarly changed to alumina (spherical, particle size 30 nm) and titanium dioxide (spherical, particle size 50 nm), respectively. C was prepared.

<< Preparation of dope >>
Dopes 101 to 119 were prepared as follows.

<Preparation of dope 101>
The dope 101 was prepared by mixing the polyimide solution A, the metal oxide particle dispersion A, the following silane coupling agent A, and the following N, N-dimethylacetamide solution of the aromatic compound A and stirring for 30 minutes.

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

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

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

<Evaluation>
For the prepared polyimide films 101 to 119, the gray value standard deviation σ, the occupied area ratio of the black portion in the binarized image, scratch resistance, and image distortion were evaluated.
The evaluation results are shown in Table I.

<Standard deviation σ of gray value and black area occupation ratio in binarized image>
In accordance with the analysis method of the projected image of the film shown in FIG. 1, the standard deviation σ of 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 films 101 to 119) and the white light source 2 (S-light manufactured by Japan Technical Center Co., Ltd.) is adjusted to 60 cm. Light was irradiated from the 45 ° direction. The distance between the film sample 1 and the projection surface 3 arranged in parallel with the film sample 1 was adjusted to 70 cm, and the shadow of the film sample 1 was projected onto the projection surface 3.
The projected image is arranged at a distance of 80 cm from the projection plane 3 at a distance of 80 cm (EOS KISS50 manufactured by Canon, lens EF-S 18 = 55 mm, ISO sensitivity 100, aperture 5.6, shutter speed 1 / 10 seconds, white balance manual setting) to obtain a photographed image.

  Next, for the obtained projection 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. The photographed image was read into a personal computer using free software ImageJ.
2. A rectangular evaluation area of 1 cm × 5 cm was set in the actual captured image. At this time, the long side of the rectangle was set to the film sample transport direction.
3. The 8-bit gray scale was performed with free software ImageJ.
4). Background correction was performed with the free software ImageJ.
5. A standard deviation σ and an average value m of gray values (pixel values) in a gray scale were calculated.
6). The binarization of the rectangular evaluation area was performed using the average value m as a threshold value.
7. The area of the black part (dark part) obtained by binarization 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 Wayne Rasband.

<Scratch resistance evaluation>
About the produced polyimide films 101-119, the surface scratch resistance was evaluated by a steel wool scratch resistance test. Specifically, using a Gakushin type wear resistance tester (manufactured by Tester Sangyo Co., Ltd.), # 0000 steel wool loaded with 200 g was reciprocated 10 times on the film, and the film surface was visually checked for damage. 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, and image distortion was visually evaluated.

Specifically, using the polyimide films 101 to 119 as a transparent substrate, a reflective electrode made of chromium is formed thereon, and a metal electrode is formed on the reflective electrode using ITO (tin-doped indium oxide) as a metal electrode (anode). did.
As the organic functional layer, poly (3,4-ethylenedioxythiophene) -polystyrene sulfonate (PEDOT: PSS) is formed as a hole transport layer on the anode with a thickness of 80 nm by sputtering, 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 using a shadow mask. As the red light emitting layer R, 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-evaporated (mass ratio 99: 1) to 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 light emitting compound were co-evaporated (mass ratio 99: 1) to 100 nm. The thickness was formed. The blue light-emitting layer B was formed with a thickness of 100 nm by co-evaporating 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, a film of calcium is formed with a thickness of 4 nm by a vacuum deposition method, and a second cathode is formed on the first cathode. Aluminum was formed with a thickness of 2 nm. Here, the aluminum used as the second cathode has a role of preventing the calcium as the first cathode from causing chemical alteration when a transparent conductive film is formed thereon by a sputtering method. Next, a transparent conductive film having a thickness of 80 nm was formed on the cathode by sputtering to form a transparent electrode. Here, ITO was used as the transparent conductive film. Furthermore, a silicon nitride film having a thickness of 200 nm was formed on the transparent electrode by a CVD method to form an insulating layer, and a 20 cm × 20 cm organic EL element unit was produced.

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

  Next, under a reduced pressure condition 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 the pressure was applied and held 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 produced organic EL display device was visually observed from an oblique angle of 45 °, and evaluated according to the following evaluation criteria.

○: Level at which image distortion is not a concern ×: Level at which image distortion is a concern

<Summary>
As is apparent from Table I, it can be seen that the polyimide film of the present invention is superior in terms of scratch resistance and image distortion as compared with the polyimide film of the comparative example.
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 the content is in the transparent polyimide film. When the projection image of the transparent polyimide film is evaluated with respect to the total solid content (100% by mass), the gray value standard deviation σ in an 8-bit gray scale is 0.50 to 1. A transparent polyimide film for a flexible display front plate that is within the range of 10 and the image area of the black portion in the binarized image is adjusted to 50% or less while suppressing image distortion and excellent scratch resistance. Was found to be useful in providing

[Example 2]
<< Preparation of dope >>
Dopes 201 to 211 were prepared as follows.

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

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

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

<< Preparation of polyimide film >>
The obtained dopes 201 to 211 are each coated on a smooth glass plate on which a small amount of a release agent has been dispersed with a coater, and then heated on a hot plate at 160 ° C. for 30 minutes to produce a self-supporting film. did. After fixing the film peeled from the glass plate to a stainless steel mold with clips, the organic solvent is almost completely removed (less than 1% by mass) by placing it in a vacuum dryer at 200 ° C. for 2 hours, and a polyimide film 201 to 211 were obtained.

<Evaluation>
For the produced polyimide films 201 to 211, the gray value standard deviation σ, the occupied area ratio of the black portion in the binarized image, scratch resistance, and image distortion were evaluated in the same manner as in Example 1.
The evaluation results are shown in Table II.

<Summary>
As is apparent from Table II, it can be seen that the polyimide film of the present invention is superior in terms of scratch resistance and image distortion as compared with the polyimide film of the comparative example.
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 the content is in the transparent polyimide film. When the projection image of the transparent polyimide film is evaluated with respect to the total solid content (100% by mass), the gray value standard deviation σ in an 8-bit gray scale is 0.50 to 1. A transparent polyimide film for a flexible display front plate that is within the range of 10 and the image area of the black portion in the binarized image is adjusted to 50% or less while suppressing image distortion and excellent scratch resistance. Was found to be useful in providing

[Example 3]
<< Preparation of dope >>
Dopes 301 to 309 were prepared as follows.

<Preparation of dope 301>
The dope 301 was prepared by mixing the polyimide solution A, the metal oxide particle dispersion A, and the silane coupling agent A, and stirring for 30 minutes.

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

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

The amount of metal oxide particles (silica particles) added was 50% by mass relative to the total solid content (100% by mass) in the dope.
Moreover, the addition amount of the silane coupling agent A was 1.67 mass parts with respect to the sum total (100 mass parts) of a metal oxide particle (silica particle) and a polyimide.
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 dopes 303 to 309>
Dopes 302 to 309 were prepared in the same manner as in the preparation of the dope 302 except that the addition amount of the polyimide solution, the metal oxide particle dispersion, and the azeotropic dehydrating agent were changed as shown in Table III.

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

<Evaluation>
For the produced polyimide films 301 to 309, the gray value standard deviation σ, the black area occupation ratio, scratch resistance, and image distortion were evaluated in the same manner as in Example 1.
The evaluation results are shown in Table III.

<Summary>
As is apparent from Table III, it can be seen that the polyimide film of the present invention is superior in terms of scratch resistance and image distortion as compared with the polyimide film of the comparative example.
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 the content is in the transparent polyimide film. When the projection image of the transparent polyimide film is evaluated with respect to the total solid content (100% by mass), the gray value standard deviation σ in an 8-bit gray scale is 0.50 to 1. A transparent polyimide film for a flexible display front plate that is within the range of 10 and the image area of the black portion in the binarized image is adjusted to 50% or less while suppressing image distortion and excellent scratch resistance. Was found to be useful in providing

1 Film sample (Polyimide film)
2 White light source 3 Projection plane 4 Camera

Claims (8)

A transparent polyimide film for a flexible display front plate containing metal oxide particles, a silane coupling agent and a polyimide,
The metal oxide particles have an average primary particle size in the range of 10 to 100 nm and a content of 20 to 70% by mass with respect to the total solid content (100% by mass) in the transparent polyimide film. Is in range,
When analyzing the projected image of the transparent polyimide film, the standard deviation σ of the gray value in the 8-bit gray scale is in 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 transparent polyimide film for a flexible display front plate, characterized by being adjusted to the above.   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, further comprising an aromatic compound.   The said silane coupling agent has at least 1 group selected from an acryl group, a methacryl group, an isocyanurate group, a phenyl group, and a fluoro group, It is any one of Claim 1 to 3 characterized by the above-mentioned. Transparent polyimide film for flexible display front plate as described in 1.   The said polyimide is a fluorinated polyimide, The transparent polyimide film for flexible display front plates as described in any one of Claim 1- Claim 4 characterized by the above-mentioned. A method for producing a transparent polyimide film for a flexible display front plate containing metal oxide particles, a silane coupling agent and a polyimide,
Preparing a dope containing the metal oxide particles, the silane coupling agent, the polyimide, and a solvent;
Casting the dope on a support to form a web;
Have
The metal oxide particles have an average primary particle size in the range of 10 to 100 nm and a content of 20 to 70% by mass with respect to the total solid content (100% by mass) in the transparent polyimide film. Is in range,
When evaluating the projected image of the transparent polyimide film, 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. The manufacturing method of the transparent polyimide film for flexible display front plates 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.

Images