WO2016152459A1

WO2016152459A1 - Polyimide-based optical film, process for producing same, and organic electroluminescent display

Info

Publication number: WO2016152459A1
Application number: PCT/JP2016/056756
Authority: WO
Inventors: 健太間島; 梅田　博紀; 康敏伊藤; 直矢岩上
Original assignee: コニカミノルタ株式会社
Priority date: 2015-03-24
Filing date: 2016-03-04
Publication date: 2016-09-29
Also published as: TW201638153A; JP6635110B2; KR20170110704A; KR102046699B1; JPWO2016152459A1

Abstract

The present invention addresses the problem of providing a polyimide-based optical film which has improved flatness. When this optical film is used in a surface of an organic electroluminescent display and viewed through polarizing sunglasses, film unevenness is less conspicuous and excellent image visibility is attained. The polyimide-based optical film according to the present invention includes a transparent heat-resistant resin having an imide structure, and is characterized in that a rectangular area cut out of a projected image of the polyimide-based optical film has a standard deviation σ of gray-scale values of 0.50-1.10 and that a binarization image of the rectangular area has black portions in an areal proportion regulated to a value in the range of 10-50%.

Description

POLYIMIDE OPTICAL FILM, PROCESS FOR PRODUCING THE SAME, AND ORGANIC ELECTROLUMINESCENT DISPLAY

The present invention relates to a polyimide-based optical film, a method for producing the same, and an organic electroluminescence display. More specifically, the present invention relates to a polyimide-based optical film that has improved planarity, and when used on the surface of an organic electroluminescence display device, the unevenness of the film when viewed through polarized sunglasses is not noticeable and is excellent in visibility. .

Conventionally, glass has been used for the outermost surface of an organic electroluminescence display, but in recent years, a material having both folding resistance and transparency has been demanded as a substitute for glass as it becomes flexible.

One of the materials is a compound having an imide structure, and a polyimide-based optical film as disclosed in Patent Document 1 is known, but a solution casting using a high-boiling solvent such as dimethylacetamide is known. The polyimide optical film formed by the film method has poor flatness, and organic electroluminescence displays using this optical film as the outermost surface show that the unevenness of the film becomes noticeable when viewed through polarized sunglasses. It was.

Japanese Patent No. 5589384

The present invention has been made in view of the above-mentioned problems and situations, and its solution is to improve the flatness and to prevent unevenness of the film when viewed through polarized sunglasses when used on the surface of an organic electroluminescence display. Is an inconspicuous and excellent visibility of a polyimide optical film, a method for producing the same, and an organic electroluminescence display using the same.

In order to solve the above problems, the present inventor, in the process of examining the cause of the above problems, in the rectangular area cut out from the projected image of the optical film, the grayscale standard deviation σ and the binarized image of the rectangular area The area occupied by the black portion of the film is improved by the polyimide-based optical film adjusted to a specific range, and when used on the surface of an organic electroluminescence display device, the film is viewed through polarized sunglasses. It has been found that a polyimide-based optical film in which unevenness is not noticeable can be obtained.

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

1. A polyimide optical film containing a transparent heat resistant resin having an imide structure,
In a predetermined rectangular area cut out from the projected image of the polyimide optical film, the standard deviation σ of the gray scale is in the range of 0.50 to 1.10, and the black portion in the binarized image of the rectangular area The polyimide-based optical film is characterized in that the area occupied by is adjusted to 50% or less.

2. The transparent heat resistant resin having the imide structure is a polyimide having a structure represented by the following formula (1), a polyimide having a structure represented by the following formula (2) or the following formula (3), a polyesterimide, a polyamideimide. And a polyimide-based optical film according to item 1, wherein the polyimide-based optical film is selected from polyetherimide and polyetherimide.

(In the formula (3), X is a divalent aliphatic group having 2 to 39 carbon atoms, a divalent alicyclic group having 3 to 39 carbon atoms, or a divalent aromatic group having 6 to 39 carbon atoms. A divalent group consisting of a group or a combination thereof, and the main chain of X includes —O—, —SO ₂ —, —CH ₂ —, —C (CH ₃ ) ₂ —, —OSi (CH ₃ ) _At least one linking group selected from the group consisting of ₂ —, —C ₂ H ₄ O— and —S— may be interposed, and X is selected from the group consisting of a carboxy group, a hydroxy group or a carbonyl group. And may have at least one functional group.)
3. A method for producing a polyimide-based optical film for producing the polyimide-based optical film according to

item

1 or 2, wherein a dope containing the transparent heat-resistant resin having the imide structure and dichloromethane is prepared, and the solution flow A method for producing a polyimide-based optical film, wherein the film is formed by a film-forming method.

4. In the film forming process, the film is stretched at a magnification of 1.05 times or more in at least one direction of the longitudinal direction or the width direction, and then the (glass transition temperature Tg-150) to (glass transition temperature Tg-30) of the film. The method for producing a polyimide-based optical film according to item 3, wherein the bending treatment is performed 150 times or more while being conveyed by a roller at a drying temperature in the range of ° C.

5. 5. The method for producing a polyimide-based optical film according to

item

3 or 4, wherein the film thickness is adjusted within a range of 25 to 100 μm.

6. An organic electroluminescence display comprising the polyimide-based optical film according to

item

1 or 2.

By the above means of the present invention, the planarity is improved, and when used on the surface of an organic electroluminescence display, the unevenness of the film when viewed through polarized sunglasses is not noticeable, and the polyimide optical film having excellent visibility, and its production A method and an organic electroluminescent display using the method can be provided.

The expression mechanism or action mechanism of the effect of the present invention is not clear, but is presumed as follows.

According to the study by the present inventors, a polyimide-based optical film that is commercially available or disclosed in Patent Document 1 has poor flatness, and an organic electroluminescence display (hereinafter referred to as organic) using the optical film as the outermost surface. When it was viewed through polarized sunglasses, it was found that the unevenness of the film was conspicuous, and the visibility was inferior to optical films of other materials.

In the visibility analysis, when the polyimide-based optical film was projected using a white light source and the image was observed, for example, there were more unevenness such as horizontal rows and spots than a general-purpose triacetyl cellulose (TAC) film. I understood. That is, a polyimide-based optical film with a lot of unevenness cuts the projected image into a predetermined rectangular area and takes the standard deviation σ of the gray scale of the area, and the σ value is large, and the image in the area is binarized. It was found that the area of the black part was large.

In the present invention, when producing a polyimide-based optical film, a compound having an imide structure is cast by solution casting using a low boiling point solvent (for example, dichloromethane or the like), and further bent by a predetermined number of times while being conveyed by a roller. By applying the above, the gray scale standard deviation σ and the area of the black portion when binarized can be reduced. As a result, the flatness of the polyimide optical film is improved, and the film is used as the outermost surface. It has been found that unevenness can be made inconspicuous even when the organic EL display is viewed through polarized sunglasses.

Schematic diagram for analyzing a film projection image according to the present invention Schematic diagram of a bending processing apparatus preferably applicable to the present invention Schematic diagram of organic EL display Projected image of the polyimide-based optical film of the present invention Binary image of polyimide optical film of the present invention Gray scale standard deviation of the polyimide-based optical film of the present invention Projected image of comparative example polyimide optical film Binarized image of comparative polyimide-based optical film Gray scale standard deviation of polyimide optical film of comparative example Projected image of comparative example polyimide optical film Binarized image of comparative polyimide-based optical film Gray scale standard deviation of polyimide optical film of comparative example Projected image of comparative example polyimide optical film Binarized image of comparative polyimide-based optical film Gray scale standard deviation of polyimide optical film of comparative example

The polyimide-based optical film of the present invention is a polyimide-based optical film containing a transparent heat-resistant resin having an imide structure, and has a grayscale standard deviation σ in a rectangular area cut out from the projected image of the polyimide-based optical film. , 0.50 to 1.10, and the area occupied by the black portion in the binarized image of the rectangular area is adjusted to 50% or less. This feature is a technical feature common to the inventions according to claims 1 to 6.

As an embodiment of the present invention, from the viewpoint of manifesting the effects of the present invention, the transparent heat-resistant resin having the imide structure is a polyimide having a structure represented by the formula (1), the formula (2) or the formula ( From the viewpoint of obtaining a polyimide-based optical film excellent in smoothness, heat resistance, and transparency, it is preferable to select from polyimide, polyesterimide, polyamideimide and polyetherimide having the repeating unit represented by 3).

The method for producing a polyimide-based optical film of the present invention is preferably prepared by preparing a dope containing the transparent heat-resistant resin having the imide structure and dichloromethane and forming the dope by a solution casting film forming method. In the process, the film is stretched at a magnification of 1.05 times or more in at least one direction of the longitudinal direction or the width direction, and then the (glass transition temperature Tg-150) to (glass transition temperature Tg-30) ° C. of the film. Performing the bending process 150 times or more while transporting the roller at a drying temperature within the range improves the smoothness, and when used on the surface of the organic electroluminescence display, unevenness of the film when viewed through polarized sunglasses is observed. From the viewpoint of obtaining a polyimide-based optical film that is not conspicuous and has excellent visibility, this is a preferred production method.

The polyimide optical film of the present invention is a preferred embodiment from the viewpoint of obtaining an optical film having a thin film and good flatness by adjusting the film thickness within a range of 25 to 100 μm.

The polyimide-based optical film of the present invention is preferably provided in an electroluminescence display, and is preferable from the viewpoint of excellent visibility when viewed through sunglasses.

Hereinafter, the present invention, its components, and modes and modes for carrying out the present invention will be described in detail. In the present application, “˜” is used to mean that the numerical values described before and after it are included as a lower limit value and an upper limit value.

<< Outline of Polyimide Optical Film of the Present Invention >>
The polyimide-based optical film of the present invention (hereinafter sometimes referred to as polyimide film) is a polyimide-based optical film containing a transparent heat-resistant resin having an imide structure, and was cut out from the projected image of the polyimide-based optical film. In a predetermined rectangular area, the grayscale standard deviation σ is in the range of 0.50 to 1.10, and the area occupied by the black portion in the binarized image of the rectangular area is adjusted to 50% or less. It is characterized by that.

Here, a method for analyzing a film projection image according to the present invention will be described.

FIG. 1 is a schematic diagram for analyzing a film projection image according to the present invention.

The white light source 2 (S-light, manufactured by Japan Technical Center Co., Ltd.) is irradiated at an angle of 45 ° with respect to the film sample 1 while adjusting the distance between the film sample 1 and the white light source 2 to 60 cm. The distance to the surface 3 is projected as 70 cm. Camera 4 (for example, Canon EOS KISS50, lens EF-S 18 = 55 mm, ISO sensitivity 100, aperture 5.6, shutter speed 1/10 second, white balance at a distance of 80 cm in the direction of 90 ° from the projection plane 3 The projection image is photographed by manual setting) to obtain a photographed image.

Next, the photographed image is analyzed according to the following procedure.

[Mura numerical procedure for smoothness]
1. The captured image is read into a personal computer using the free software ImageJ.

2. A rectangular evaluation area that is 1 cm × 5 cm in an actual captured image is set. At that time, the long side of the rectangle is set to be in the transport direction of the film sample.

3. Using free software ImageJ, 8-bit conversion (gray scale) is performed.

4. Background correction is performed by the free software ImageJ.

5. The standard deviation σ and the average value m of the gray value in the gray scale are calculated.

6. The rectangular evaluation area is binarized using the average value m as a threshold.

7. The black portion area ratio K (%) is calculated by dividing the area of the black portion (dark portion) obtained by the binarization by the entire area.

Here, free software ImageJ refers to ImageJ1.32S created by Wayne Rasband.

In addition, the background correction is output as different brightness even when the right half area and the left half area of the image have the same brightness, or as the image moves from the left side to the right side of the image. When it is output as a result of gradually brightening, background correction is performed, histogram calculation, average gradation calculation, and binarization processing are performed to obtain the area ratio K (%) of the black part (dark part) Is preferred.

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

Gray data N pieces of data x1, x2,... XN is a population, and an arithmetic mean (population average) m of the population is obtained by the following formula 1.

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

The positive square root σ of this variance (σ ² ) is taken as the standard deviation σ.
The standard deviation σ of the gray value in the gray scale of the polyimide-based optical 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. More preferably, it is in the range of ˜1.05.

In addition, the area occupied by the black portion in the binarized image of the rectangular area of the polyimide-based optical film of the present invention is adjusted to 50% or less. A range of 50% is preferable, and a range of 40 to 45% is more preferable.

<Configuration of polyimide optical film of the present invention>
The polyimide-based optical film of the present invention contains a compound having an imide structure, and the transparent heat-resistant resin having the imide structure has a structure represented by the following formula (1), the following formula (2) or It is preferably selected from polyimide, polyesterimide, polyamideimide, and polyetherimide having a structure represented by the following formula (3).

[1] Transparent heat-resistant resin having an imide structure [1.1] Polyimide having a structure represented by the formula (1) The transparent heat-resistant resin having an imide structure according to the present invention (hereinafter also referred to as polyimide resin). It is preferable that it is a polyimide resin represented by following formula (1) obtained by chemically imidizing a polyimide precursor.

[Polymerization of polyimide precursor]
An example of the manufacturing method of the manufacturing method of the polyimide precursor which has a structure represented by Formula (1) used by this invention is shown below.

First, 2,2′-bis (trifluoromethyl) -4,4′-diaminobiphenyl (TFMB), which is a diamine, is dissolved in a polymerization solvent in a polymerization vessel. To this diamine solution, a powder of 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropanoic acid dianhydride (6FDA) was gradually added, and the temperature was −20 to 100 ° C. using a mechanical stirrer. The mixture is stirred in the range, preferably in the range of 20 to 60 ° C. for 1 to 72 hours. By using TFMB and 6FDA, visible light permeability and solubility are improved. The number of moles of diamine and the number of moles of tetracarboxylic dianhydride are charged at substantially equal moles. The total monomer concentration during the polymerization is 5 to 40% by mass, preferably 10 to 30% by mass. By carrying out polymerization in this monomer concentration range, a polyimide precursor solution having a uniform and high degree of polymerization can be obtained.重合 If the polymerization is carried out at a concentration lower than the above monomer concentration range, the degree of polymerization of the polyimide precursor is not sufficiently high, and the finally obtained polyimide resin film may be brittle, which is not preferable.

The polymerization solvent is not particularly limited, but N, N-dimethylacetamide, N, N-diethylacetamide, N, N-dimethylformamide, N-methyl-2-pyrrolidone, hexamethylphosphoramide, dimethylsulfoxide, γ- Butyrolactone, 1,3-dimethyl-2-imidazolidinone, 1,2-dimethoxyethane-bis (2-methoxyethyl) ether, terahydrofuran, 1,4-dioxane, picoline, pyridine, acetone, chloroform, toluene, Aprotic solvents such as xylene and protic solvents such as phenol, o-cresol, m-cresol, p-cresol, o-chlorophenol, m-chlorophenol, and p-chlorophenol can be used. These solvents may be used alone or in combination of two or more.

[Production method of polyimide resin]
The polyimide resin represented by the formula (1) can be produced by a dehydration ring-closing reaction (imidation reaction) of the polyimide precursor obtained by the above method. For the imidization reaction, chemical imidization is used in which the resulting polyimide resin exhibits better dimensional stability. Chemical imidization can be performed using a dehydrating cyclization agent (chemical imidization agent) comprising an acid anhydride of an organic acid and an organic tertiary amine. For example, by using the polyimide precursor varnish as it is or after appropriately diluting with a solvent, a dehydration cyclization reagent is added thereto and stirred at 0 to 100 ° C., preferably 20 to 60 ° C. for 0.5 to 48 hours. It can be easily imidized.

The acid anhydride of the organic acid used at that time is not particularly limited, and acetic anhydride, propionic anhydride, maleic anhydride, phthalic anhydride, etc. can be used, but the cost and ease of post-treatment are not limited. In view of the above, acetic anhydride is preferably used. The organic tertiary amine is not particularly limited, and pyridine, 1,5-dimethylpyridine, β-picoline, γ-picoline, lutidine, isoquinoline, triethylamine, N, N-dimethylaniline and the like can be used.

In the chemical imidation reaction, the amount of the acid anhydride used in the dehydration cyclization reagent is preferably in the range of 1 to 10 times mol of the theoretical dehydration amount of the polyimide precursor. The amount of catalyst used is preferably in the range of 0.1 to 2 moles relative to the acid anhydride. If the chemical imidization is carried out outside these ranges, the imidation reaction may not be completed, or the imidization may not be completed in the reaction solution and the imidization may be insufficient.
After completion of imidation, the reaction solution can be used for coating as it is, or the reaction solution is dropped into a large amount of poor solvent, or a poor solvent is added to the reaction solution, and the polyimide resin is precipitated and washed. In the case of a solvent or chemical imidization, an excess chemical imidizing agent is removed, and then dried under reduced pressure to obtain a polyimide resin powder. The poor solvent that can be used is not particularly limited as long as it does not dissolve the polyimide resin, but water, methanol, ethanol, from the viewpoint of affinity with the reaction solvent and chemical imidizing agent and ease of removal by drying. n-propanol, isopropanol and the like are preferably used.

The weight average molecular weight of the polyimide resin is not particularly limited, but is preferably from 5,000 to 2,000,000, more preferably from 10,000 to 1,000,000, and further preferably from 50,000 to 500,000. When the weight average molecular weight is 5000 or more, sufficient strength can be obtained in the case of a film, and dimensional stability tends to be improved, so that sufficient dimensional stability can be obtained. On the other hand, if it is 2000000 or less, the solution viscosity does not become too high and it is easy to handle. In addition, the said weight average molecular weight means the value of polyethyleneglycol conversion by size exclusion chromatography (SEC).

[1.2] Polyimide having structure represented by formula (2) or formula (3) The transparent heat resistant resin according to the present invention is a polyimide having a repeating unit represented by the following formula (2) (hereinafter, polyimide). P)) or a polyimide composed of a repeating unit represented by the formula (2) and a repeating unit represented by the following formula (3) is preferable.

(In the formula (3), X is a divalent aliphatic group having 2 to 39 carbon atoms, a divalent alicyclic group having 3 to 39 carbon atoms, or a divalent aromatic group having 6 to 39 carbon atoms. A divalent group consisting of a group or a combination thereof, and the main chain of X includes —O—, —SO ₂ —, —CH ₂ —, —C (CH ₃ ) ₂ —, —OSi (CH ₃ ) _At least one linking group selected from the group consisting of ₂ —, —C ₂ H ₄ O— and —S— may be interposed, and X is selected from the group consisting of a carboxy group, a hydroxy group or a carbonyl group. And may have at least one functional group.)
The polyimide resin is composed of a repeating unit represented by the formula (2), or a repeating unit represented by the formula (2) and a repeating unit represented by the formula (3). The ratio of the repeating units to be used is more than 50 mol% of all repeating units, preferably 70 mol% or more, more preferably 80 mol% or more (each including 100 mol%). When the proportion of the repeating unit represented by the formula (2) exceeds 50 mol% of all the repeating units, low water absorption can be achieved. Get higher. The polyimide P may be either a block copolymer or a random copolymer.

X in the above formula (3) is the following formula (4);

2 is composed of a divalent aliphatic group having 2 to 39 carbon atoms, a divalent alicyclic group having 3 to 39 carbon atoms, a divalent aromatic group having 6 to 39 carbon atoms, or a combination thereof. Is a valent group. The main chain of X includes —O—, —SO ₂ —, —CH ₂ —, —C (CH ₃ ) ₂ —, —OSi (CH ₃ ) ₂ —, —C ₂ H ₄ O—, and —S. At least one linking group selected from the group consisting of — may intervene. X may have at least one functional group selected from the group consisting of a carboxy group, a hydroxy group, and a carbonyl group (included in the main chain of X). Specific examples of X include polyalkylene, polyoxyalkylene, xylylene and their alkyl-substituted, halogen-substituted, carboxy-substituted, and hydroxy-substituted divalent aliphatic groups; cyclohexane, dicyclohexylmethane, dimethylcyclohexane, Divalent alicyclic groups derived from isophorone, norbornane and their alkyl-substituted, halogen-substituted, carboxy-substituted, hydroxy-substituted, etc .; and benzene, naphthalene, biphenyl, diphenylmethane, diphenyl ether, diphenylsulfone, benzophenone And divalent aromatic groups derived from these alkyl-substituted, halogen-substituted, carboxy-substituted, hydroxy-substituted and the like. Moreover, it is preferable that the structure represented by Formula (4) is a structure represented by following formula (5) from a viewpoint of resin strength.

When polyimide P is used as a solution, its molecular weight is preferably expressed by viscosity, particularly logarithmic viscosity. The logarithmic viscosity η (measured at 30 ° C. using a 0.5 g / dL N-methyl-2-pyrrolidone solution) of the polyimide P is preferably 0.3 to 2 dL / g. If it is less than 0.3 dL / g, the strength of the polyimide resin itself is weak, and an optical film having sufficient peel strength cannot be obtained. If it exceeds 2.0 dL / g, the solution will become highly viscous and difficult to cast, requiring significant dilution, making handling difficult.

Usually, the molecular end of polyimide P is an amino group, a carboxy group, or a carboxylic anhydride group. By reacting a compound having a carboxylic acid anhydride group or an amino group at the molecular end, the functional group at the molecular end is reduced as much as possible, or an intentionally functional group such as an amino group or a carboxy group is present at the molecular end. Groups and other substituents can be introduced. In order to reduce the water absorption rate, a substituent having a small polarity (substituent having no functionality) may be introduced at the molecular end. The water absorption of the polyimide P measured by the method described later is preferably 2.5% or less. The minimum value of water absorption that can be achieved industrially is usually about 1%.

Polyimide P consists of 1,2,4,5-cyclohexanetetracarboxylic acid, 1,2,4,5-cyclohexanetetracarboxylic dianhydride (HPMDA) and 1,2,4,5-cyclohexanetetracarboxylic acid esters. It is obtained by reacting at least one tetracarboxylic acid component (Y) selected from reactive derivatives such as diamine and at least one diamine component (Z) selected from diamines and reactive derivatives thereof. As the tetracarboxylic acid component (Y), HPMDA is preferable. In addition, the tetracarboxylic acid component (Y) and the diamine component (Z) include isomers.

Examples of the diamine component (Z) include diamine, diisocyanate, and diaminodisilane, and diamine is preferred. The diamine component (diamine component (Z1)) for forming the repeating unit of the above formula (1) is 4,4′-bis (4-aminophenoxy) biphenyl (BAPB) and a reactive derivative thereof. The diamine component (diamine component (Z2)) for forming the repeating unit (3) is NH ₂ —X—NH ₂ (X is the same as described above) and reactive derivatives thereof.

The diamine component (Z2) may be an aromatic diamine, an aliphatic diamine, an alicyclic diamine, a reactive derivative of the above diamine, or a mixture thereof, including a carboxy group, a hydroxy group, and a carbonyl group (in the main chain of X). It may have at least one functional group selected from the group consisting of: In the present invention, “aromatic diamine” means a diamine in which an amino group is directly bonded to an aromatic ring, and an aliphatic group, an alicyclic group, an aromatic group, other It may contain a substituent. “Aliphatic diamine” refers to a diamine in which an amino group is directly bonded to an aliphatic group, and the structure includes an aliphatic group, an alicyclic group, an aromatic group, and other substituents. May be. “Alicyclic diamine” refers to a diamine in which an amino group is directly bonded to an alicyclic group, and an aliphatic group, an alicyclic group, an aromatic group, and other substituents are partly included in the structure. It may be included. For example, 2,2-bis [4- (4-aminophenoxy) phenyl] propane (BAPP) is an aromatic diamine because an amino group is directly bonded to an aromatic ring (benzene ring), and m-xylyl Range amine (MXDA) is an aliphatic diamine because the amino group is directly bonded to an aliphatic group (methylene group).

In general, when tetracarboxylic dianhydride is reacted with an aliphatic diamine or alicyclic diamine, the polyamic acid as an intermediate product and the amino group derived from the aliphatic diamine or alicyclic diamine form a strong salt. In addition, it is difficult to obtain a high molecular weight polyimide. Therefore, it is necessary to devise such as using a solvent having a relatively high salt solubility, such as cresol. However, when 1,2,4,5-cyclohexanetetracarboxylic dianhydride is used as the tetracarboxylic dianhydride, a polyamic acid and a salt having a relatively weak bond between an amino group derived from an aliphatic diamine or an alicyclic diamine. Thus, the imidization reaction proceeds relatively easily and can be easily increased in molecular weight.

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, , 4-bis (aminomethyl) cyclohexane, p-xylylenediamine, m-xylylenediamine, siloxane diamines and the like.

Examples of the alicyclic diamine include 4,4′-diaminodicyclohexylmethane, isophorone diamine, norbornane diamine, and the like.

Examples of the aromatic diamine include 1,4-phenylene diamine, 1,3-phenylene diamine, 2,4-toluene diamine, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'- Diaminodiphenylmethane, 1,4-bis (4-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,3-bis (3-aminophenoxy) benzene, α, α'-bis (4 -Aminophenyl) -1,4-diisopropylbenzene, α, α'-bis (3-aminophenyl) -1,4-diisopropylbenzene, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 4,4'-diaminodiphenylsulfone, bis [4- (4-aminophenoxy) phenyl] sulfone, bis [4- ( - aminophenoxy) phenyl] sulfone, 2,6-diaminonaphthalene, 1,5-diaminonaphthalene and the like.

Examples of the diamine having a functional group include 3,3′-dicarboxy-4,4′-diaminodiphenylmethane, 3,5-diaminobenzoic acid, 3,3′-dihydroxy-4,4′-diaminobiphenyl, 2,4-diaminophenol, 4,4'-diaminobenzophenone, 3,3'-diaminobenzophenone, and in particular, 3,3'-dicarboxy-4,4'-diaminodiphenylmethane (MBAA), 3,5 -Diaminobenzoic acid (DBA), 3,3'-dihydroxy-4,4'-diaminobiphenyl (HAB), 4,4'-diaminobenzophenone (4,4'-DBP) are preferred.

It is preferable to use MXDA or BAPP as the diamine component (Z2).

The polyimide P contains the tetracarboxylic acid component (Y) with respect to 1 mol of the diamine component (Z) (diamine component (Z1) or diamine component (Z1) + diamine component (Z2)), preferably 0.00. It is produced by reacting 66 to 1.5 mol, more preferably 0.9 to 1.1 mol, and still more preferably 0.97 to 1.03 mol.

For example, a polyimide P having a logarithmic viscosity η within the above range is produced by adjusting at least one of the conditions such as the use ratio of raw materials, reaction temperature and time, presence / absence and use of a terminal terminator, and the amount of catalyst. can do. Those skilled in the art can easily adjust the conditions by performing a preliminary reaction or the like. For example, when the logarithmic viscosity η is adjusted by the molar ratio of the tetracarboxylic acid component (Y) and the diamine component (Z) and the reaction time, the closer the molar ratio is to 1, the longer the reaction time, The logarithmic viscosity η increases within the above range. As the molar ratio is far from 1 in the range of 0.66 to 1.5 and the reaction time is shorter, the logarithmic viscosity η is smaller in the range. In the solution polymerization method, the relationship between the viscosity of the reaction solution, the reaction time, and other reaction conditions, and the logarithmic viscosity corresponding thereto is obtained in advance, and the end point of the reaction is determined based on this relationship. A polyimide P having a logarithmic viscosity η can be produced. The reaction time is preferably 2 to 12 hours, and the reaction temperature is preferably 180 to 205 ° C.

The polyimide P is usually produced as an organic solvent solution.
The organic solvent is not particularly limited. For example, N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-diethylacetamide, N, N-dimethylformamide, N, N-diethylformamide, N-methyl Caprolactam, hexamethylphosphoramide, tetramethylenesulfone, dimethylsulfoxide, m-cresol, phenol, p-chlorophenol, 2-chloro-4-hydroxytoluene, diglyme, triglyme, tetraglyme, dioxane, γ- Butyrolactone, dioxolane, cyclohexanone, cyclopentanone and the like can be used, and two or more kinds may be used in combination. However, considering the performance of polyimide varnish composed of polyimide P and solvent, N-methyl-2-pyrrolidone (NMP), N, N-dimethylacetamide (DMAC), and γ-butyrolactone (GBL) may be used alone or in combination. preferable. The organic solvent is used in such an amount that the polyimide P concentration in the obtained organic solvent solution is preferably 1 to 50% by mass, more preferably 5 to 40% by mass. In the case of production by solution polymerization, a poor solvent such as hexane, heptane, benzene, toluene, xylene, chlorobenzene, o-dichlorobenzene and the like can be used together with the above solvent to such an extent that the polymer does not precipitate.

Polyimide P is obtained by (1) solution polymerization method, (2) preparing a polyamic acid solution, forming a film and imidizing it, and (3) obtaining a salt or imide oligomer such as HPMDA half ester salt, It can be produced by a method of performing phase polymerization, (4) a method of reacting tetracarboxylic dianhydride and diisocyanate, or other conventionally known methods. You may use each method together. The reaction between the tetracarboxylic acid component (Y) and the diamine component (Z) may be carried out in the presence of a conventionally known catalyst such as an acid, a tertiary amine or an anhydride.

Among these methods, since an organic solvent solution of polyimide P can be obtained directly, the following solution polymerization methods (1) to (3) are preferable.
(1) A mixture containing a diamine component (Z), an organic solvent and, if necessary, a catalyst is stirred at 10 to 600 rpm to obtain a homogeneous solution, which is maintained at a temperature of 30 to 90 ° C., and the tetracarboxylic acid component (Y) And if necessary, a catalyst is added.
(2) A mixture containing a tetracarboxylic acid component (Y), an organic solvent, and, if necessary, a catalyst is stirred at 10 to 600 rpm to obtain a homogeneous solution, which is kept at a temperature of 30 to 90 ° C., and a diamine component (Z) And if necessary, a catalyst is added.
(3) After the method (1) or (2), the temperature is raised to 160 to 230 ° C., preferably 180 to 205 ° C. over 0.1 to 6 hours. This temperature depends on the boiling point of the organic solvent used. While collecting the components to be removed outside the reaction system, the temperature is kept substantially constant for 0.5 to 24 hours, preferably 2 to 12 hours. Thereafter, if necessary, an organic solvent is further added and cooled to an appropriate temperature.

Solution polymerization for producing polyimide P includes trimethylamine, triethylamine (TEA), tripropylamine, tributylamine, triethanolamine, N, N-dimethylethanolamine, N, N-diethylethanolamine, triethylenediamine, N- The reaction may be performed in the presence of at least one catalyst selected from tertiary amine compounds such as methylpyrrolidine, N-ethylpyrrolidine, N-methylpiperidine, N-ethylpiperidine, imidazole, pyridine, quinoline and isoquinoline. When used, the catalyst is preferably used in an amount of 0.1 to 100 mol%, more preferably 1 to 10 mol% of the tetracarboxylic acid component (Y).

[1.3] Polyesterimide The polyesterimide according to the present invention is preferably a compound having a structure represented by the following formula (6).

[Compound having structure represented by formula (6)]
The polyesterimide resin which concerns on this invention contains the structure represented by Formula (6) in a structural unit.

In Formula (6), R1 is a compound having a structure represented by Formula (7), a compound having a structure represented by Formula (8), or a compound having a structure represented by Formula (9).

The compound having the structure represented by formula (7) will be described.

In the formula (7), R represents a chain aliphatic group, a cycloaliphatic group or an aromatic group, and a plurality of R may be the same as or different from each other. These chain aliphatic groups, cycloaliphatic groups or aromatic groups 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. When it exceeds 25, the heat resistance tends to decrease.

The chain aliphatic group, cycloaliphatic group or aromatic group is “chain aliphatic compound having a divalent hydroxy group”, “cycloaliphatic compound having a divalent hydroxy group” or “2 A residue derived from a “diol compound” such as an “aromatic compound having a valent hydroxy group” is desirable. Further, it may be a residue derived from the above “diol compound” and “polycarbonate diol compound” which can be polymerized from carbonates, phosgene and the like.

As the “chain aliphatic compound having a divalent hydroxy group”, a branched or linear diol compound having two hydroxy groups can be used. Examples thereof include an alkylene diol compound, a polyoxyalkylene diol compound, a polyester diol compound, and a polycaprolactone diol compound. Examples of branched or linear diol compounds having two hydroxy groups that can be used as the “chain aliphatic compound having a divalent hydroxy group” are given below.

Examples of the alkylene diol compound include ethylene glycol, diethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, and 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 -Cyclohexanedimethanol and the like.

Examples of polyoxyalkylenediol compounds include dimethylolpropionic acid (2,2-bis (hydroxymethyl) propionic acid), dimethylolbutanoic acid (2,2-bis (hydroxymethyl) butanoic acid), polyethylene glycol, polypropylene glycol , Polytetramethylene glycol, polyoxytetramethylene glycol, random copolymers of tetramethylene glycol and neopentyl glycol, and the like. Polyoxytetramethylene glycol is preferable.

Examples of polyester diol compounds include polyester diol compounds obtained by reacting polyhydric alcohols and polybasic acids exemplified below.

Any “polyhydric alcohol” can be used as the “polyhydric alcohol component” used in the polyester diol compound. 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, cyclohexanemethanol, Neopentylhydroxypiparic acid ester, ethylene oxide adduct and propylene oxide adduct of bisphenol A, ethylene oxide adduct and propylene oxide adduct of water-added bisphenol A, 1,9-nonanediol, 2-methyloctanediol , 1,10-dodecane diol, 2-butyl-2-ethyl-1,3-propanediol, tricyclodecane methanol, polyethylene glycol, polypropylene glycol, polyether polyol such as polytetramethylene glycol or the like can be used.

As the “polybasic acid component” used in the polyester diol compound, any of various polybasic acids can be used. For example, terephthalic acid, isophthalic acid, orthophthalic acid, 1,5-naphthalic acid, 2,6-naphthalic acid, 4,4'-diphenyldicarboxylic acid, 2,2'-diphenyldicarboxylic acid, 4,4'-diphenylether dicarboxylic acid Acids, 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 polyester diol compound that can be used in the present invention, specifically, OD-X-688 (aliphatic polyester diol manufactured by DIC Corporation: adipic acid / neopentyl glycol / 1,6-hexanediol, number average Molecular weight of about 2000), Byron (registered trademark) 220 (manufactured by Toyobo Co., Ltd., polyester diol, number average molecular weight of about 2000), and the like.

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

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

“Cycloaliphatic compound having a divalent hydroxy group” or “aromatic compound having a divalent hydroxy group” includes “a compound having two hydroxy groups in an aromatic ring or cyclohexane ring”, “two "Compounds in which phenol or alicyclic alcohol is bonded with a divalent functional group", "Compounds having one hydroxy group in both nuclei of the biphenyl structure", "Compounds having two hydroxy groups in the naphthalene skeleton", etc. Is used.

Examples of the “compound having two hydroxy groups in the aromatic ring or cyclohexane ring” include hydroquinone, 2-methylhydroquinone, resorcinol, catechol, 2-phenylhydroquinone, cyclohexanedimethanol, tricyclodecanemethanol, 1,4-dihydroxycyclohexane, , 3-dihydroxycyclohexane, 1,2-dihydroxycyclohexane, 1,3-adamantanediol, dicyclopentadiene dihydrate, 2,3-dihydroxybenzoic acid, 2,4-dihydroxybenzoic acid, 2,5-dihydroxy Carboxy group-containing diol compounds such as benzoic acid, 2,6-dihydroxybenzoic acid, 3,4-dihydroxybenzoic acid, and 3,5-dihydroxybenzoic acid can be used.

Examples of “two phenols” or “a compound in which an alicyclic alcohol is bonded with a divalent functional group” include 4,4′-dihydroxydiphenyl ether, 4,4′-dihydroxydiphenylsulfone, 4, 4 '-(9-fluorenylidene) diphenol, 4,4'-dihydroxydicyclohexyl ether, 4,4'-dihydroxydicyclohexyl sulfone, bisphenol A, bisphenol F, hydrogenated bisphenol A, hydrogenated bisphenol F, and the like can be used.

Examples of “compound having one hydroxy group in both nuclei of biphenyl structure” include 4,4′-biphenol, 3,4′-biphenol, 2,2′-biphenol, 3,3 ′, 5. 5,5'-tetramethyl-4,4'-biphenol and the like can be used.

As examples of “compounds 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 compound is preferably 100 or more and 30000 or less, more preferably 150 or more and 20000 or less, and further preferably 200 or more and 10,000 or less. When the number average molecular weight is less than 100, low hygroscopicity and flexibility cannot be sufficiently exhibited. When the number average molecular weight is more than 30000, the composition and structure of the “diol compound”, and the composition and structure of the diamine component (or isocyanate component) described later. Depending on the case, phase separation may occur and the mechanical properties may not be sufficiently exhibited.

The polycarbonate diol compound may be a polycarbonate diol (copolymerized polycarbonate diol) having a plurality of types of alkylene groups as described above in its skeleton. For example, a combination of 2-methyl-1,8-octanediol and 1,9-nonanediol, a combination of 3-methyl-1,5-pentanediol and 1,6-hexanediol, 1,5-pentanediol and 1 , 6-hexanediol, and the like can be synthesized as a copolymerized polycarbonate diol. 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 diol compounds can be used in combination.

Examples of commercially available polycarbonate diol compounds that can be used in the present invention include Kuraray Kuraray Polyol C series manufactured by Kuraray Co., Ltd., Asahi Kasei Chemicals Co., Ltd. Duranol (registered trademark) 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 1,000), Kuraray Polyol C-2015N, Kuraray polyol C2065N (Kuraray Co., Ltd. carbonate diol: 2-methyl-1,8-octanediol / 1,9-nonanediol, number average molecular weight about 2,000), 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 of about 1,000), Kuraray polyol C-2050, Kuraray polyol C -2090 (Kuraray Co., Ltd.) : 3-methyl-1,5-pentanediol / 1,6-hexanediol, number average molecular weight of about 2,000), DURANOL (registered trademark) -T5650E (polycarbonate diol manufactured by Asahi Kasei Chemicals Corporation): 1,5-pentane Diol / 1,6-hexanediol, number average molecular weight of about 500), DURANOL (registered trademark) -T5651 (Asahi Kasei Chemicals Co., Ltd. polycarbonate diol: 1,5-pentanediol / 1,6-hexanediol, number average molecular weight About 1,000), DURANOL (registered trademark) -T5652 (polycarbonate diol manufactured by Asahi Kasei Chemicals Corporation: 1,5-pentanediol / 1,6-hexanediol, number average molecular weight about 2,000), and the like. it can. Preferably, Kuraray polyol C-1015N is used.

Examples of the method for producing the polycarbonate diol include transesterification between the raw diol and carbonates, and dehydrochlorination reaction between the raw 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.

[Compound having structure represented by formula (8)]
The compound having the structure represented by formula (8) will be described.

In the formula (8), R3 is a direct bond (bond) (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 a positive integer of 1 or more. The upper limit of n is not particularly limited, but is preferably 10 or less, more preferably 5 or less, and still more preferably 3 or less. X1 to X8 may be the same or different and each represents hydrogen, a halogen or an alkyl group.

Specific examples of the compound having the structure represented by the formula (8) are not particularly limited, but include diphenyl ether skeleton, diphenyl sulfone skeleton, 9-fluorenylidene diphenol skeleton, bisphenol A skeleton, bisphenol F skeleton, and bisphenol A. Examples thereof include an ethylene oxide adduct skeleton, a propylene oxide adduct skeleton of bisphenol A, a biphenyl skeleton, and a naphthalene skeleton.

The skeleton is preferably a residue derived from a compound having one hydroxy group on each of the benzene rings in the formula (8). The raw materials for the compound having the structure represented by the formula (8) 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.

Preferably, 4,4′-dihydroxydiphenyl ether, 4,4′-dihydroxydiphenyl sulfone, 4,4 ′-(9-fluorenylidene) diphenol or bisphenol A ethylene oxide adduct is preferred. More preferably, 4,4′-dihydroxydiphenyl ether or ethylene oxide adduct of bisphenol A is used.

These compounds can be used alone or in combination of two or more. By using these raw materials, the diphenyl ether skeleton or the like can be introduced at the R1 position of the formula (6).

[Compound having structure represented by formula (9)]
The compound having the structure represented by formula (9) will be described.

In the formula (9), R4 ′ is a direct bond (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 a positive integer of 1 or more. The upper limit of n is not particularly limited, but is preferably 10 or less, more preferably 5 or less, and still more preferably 3 or less. X1 ′ to X8 ′ may be the same or different and each represents hydrogen, a halogen or an alkyl group.
Specific examples of the compound having the structure represented by the formula (9) are not particularly limited, but include dicyclohexyl ether skeleton, dicyclohexyl sulfone skeleton, hydrogenated bisphenol A skeleton, hydrogenated bisphenol F skeleton, and hydrogenated bisphenol A ethylene oxide. Examples include an adduct skeleton or a propylene oxide adduct skeleton of hydrogenated bisphenol A.

The skeleton is preferably a residue derived from a compound having one hydroxy group in each of the cyclohexane rings of the formula (9). Examples of the raw material for the compound having the structure represented by the formula (9) include 4,4′-dihydroxydicyclohexyl ether, 4,4′-dihydroxydicyclohexylsulfone, hydrogenated bisphenol A, hydrogenated bisphenol F, and hydrogenated bisphenol A. An ethylene oxide adduct or a propylene oxide adduct of hydrogenated bisphenol A can be used.

Preferably, 4,4′-dihydroxydicyclohexyl ether or 4,4′-dihydroxydicyclohexyl sulfone is used.

These compounds can be used alone or in combination of two or more. By using these raw materials, the dicyclohexyl ether skeleton or the like can be introduced at the R1 position of the formula (6).

For example, the structure of formula (6) is obtained by reacting a halide of trimellitic anhydride with diols to obtain an ester group-containing tetracarboxylic dianhydride, and then the ester group-containing tetracarboxylic acid. It can be obtained by condensation reaction (polyimidation) of dianhydride and diamine or diisocyanate.

[Compound having structure represented by formula (10)]
The polyesterimide resin according to the present invention preferably further contains the structure represented by the formula (10) in the structural unit.

[R2 in Formula (6) and R2 ′ in Formula (10)]
R2 and R2 ′ will be described. R2 and R2 ′ are not particularly limited as long as they are independently a divalent chain aliphatic group, a divalent cycloaliphatic group, or a divalent aromatic group. These “divalent chain aliphatic group”, “divalent cycloaliphatic group”, and “divalent aromatic group” can be used alone or in combination of two or more.

Preferably, R2 is a compound having a structure represented by the following formula (11), and R2 ′ is a compound having a structure represented by the following formula (12).

[Compound having structure represented by formula (11)]
R2 in Formula (6) is preferably a compound having a structure represented by Formula (11) from the viewpoint of balance between heat resistance, flexibility, low hygroscopicity, and the like.

In the formula (11), R5 represents a direct bond (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 preferably a positive integer of 1 to 10, more preferably 1 to 5, and still more preferably 1 to 3. X9 to 16 may be the same or different and each represents hydrogen, a halogen or an alkyl group.

[Compound having structure represented by formula (12)]
R2 ′ in the formula (10) is preferably a compound having a structure represented by the formula (12) from the balance of heat resistance, flexibility, low hygroscopicity, and the like.

In the formula (12), R5 ′ is a direct bond (bond), an alkylene group (—C _n H _2n —), a perfluoroalkylene group (—C _n F _2n —), an ether bond (—O—), an ester bond ( And represents a carbonyl group (—CO—), a sulfonyl group (—S (═O) ₂ —), a sulfinyl group (—SO—) or a sulfenyl group (—S—). n is preferably a positive integer of 1 to 10, more preferably 1 to 5, and still more preferably 1 to 3. X9 ′ to 16 ′ may be the same or different and each represents a hydrogen, halogen or alkyl group.

In the formula (6) and the formula (10), “a divalent chain aliphatic group”, “a divalent cycloaliphatic group” or “a divalent aromatic group” is represented by the R2 position in the formula (6) and In order to introduce at the R2 ′ position of the formula (10), it is preferable to use a corresponding diamine component or diisocyanate component, respectively. That is, “aromatic diamine or the corresponding aromatic diisocyanate”, “cycloaliphatic diamine or the corresponding cycloaliphatic diisocyanate”, “chain aliphatic diamine or the corresponding chain aliphatic diisocyanate” are appropriately used. By selecting, a polyesterimide resin excellent in heat resistance, flexibility and low hygroscopicity can be obtained.

R2 in formula (6) and R2 ′ ジアミン in formula (10) or the corresponding diisocyanate component may be the same or different. If based on the preferable manufacturing method mentioned later, it is preferable that it is the same.

A diamine component having R2 and R2 ′ as a basic skeleton or a diisocyanate component corresponding thereto will be described.

Specific examples of the “aromatic diamine or the corresponding aromatic diisocyanate” include 2,2′-bis (trifluoromethyl) benzidine, p-phenylenediamine, m-phenylenediamine, , 4-diaminotoluene, 2,5-diaminotoluene, 2,4-diaminoxylene, 2,4-diaminodurene, 4,4'-diaminodiphenylmethane, 4,4'-methylenebis (2-methylaniline), 4, 4'-methylenebis (2-ethylaniline), 4,4'-methylenebis (2,6-dimethylaniline), 4,4'-methylenebis (2,6-diethylaniline), 4,4'-diaminodiphenyl ether, 3 , 4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, 2,4 -Diaminodiphenyl ether, 4,4'-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 Yl) hexafluoropropane, 2,2-bis (4-aminophenyl) hexafluoropropane, diamino terphenyl, and the like. These can be used in combination of two or more.

Examples of the “cycloaliphatic diamine or the corresponding cycloaliphatic diisocyanate” include trans-1,4-diaminocyclohexane, cis-1,4-diaminocyclohexane, 1,4-diamino, as diamine compounds. Cyclohexane (trans / cis mixture), 1,3-diaminocyclohexane, 4,4'-methylenebis (cyclohexylamine) (tonthus, cis, 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'-methyl Bis (2-methylcyclohexylamine), 4,4'-methylenebis (2-ethylcyclohexylamine), 4,4'-methylenebis (2,6-dimethylcyclohexylamine), 4,4'-methylenebis (2,6- Diethyl cyclohexylamine), 2,2-bis (4-aminocyclohexyl) propane, 2,2-bis (4-aminocyclohexyl) hexafluoropropane and the like. These can be used in combination of two or more.

Examples of the “chain aliphatic diamine or the corresponding chain aliphatic diisocyanate” include 1,3-propanediamine, 1,4-tetramethylenediamine, 1,5-pentamethylenediamine, 1, Examples include 6-hexamethylene diamine, 1,7-heptamethylene diamine, 1,8-octamethylene diamine, and 1,9-nonamethylene diamine. These can be used in combination of two or more.

In view of the balance of heat resistance, flexibility, low hygroscopicity, and the like, the preferred component as the diamine component of R2 ′ in formula (6) and R2 ′ in formula (12) or the corresponding diisocyanate component is exemplified as the diamine compound. 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 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenyl ether, 1,5-naphthalenediamine, o-tolidine, and further preferred is 4,4′-diaminodiphenylmethane, 4,4 ′. -Diaminodiphenyl ether, o-tolidine. Most preferred is a residue derived from 4,4'-diaminodiphenylmethane, o-tolidine.

When all the structural units constituting the polyesterimide resin are 100 mol%, the structure represented by the formula (6), or the sum of the structure represented by the formula (6) and the structure represented by the formula (10) Is preferably contained in an amount of 20 mol% or more, more preferably 50 mol% or more, and even more preferably 70 mol% or more. Resin composition having both flexibility and low hygroscopicity when the structure represented by formula (6) and formula (10) is less than 20 mol% when the total constitutional units constituting the polyesterimide resin are 100 mol% Manufacture of things may be difficult.

In the polyesterimide resin according to the present invention, the molar ratio of the structure represented by the formula (6) and the structure represented by the formula (10) is formula (6) / formula (10) = 99/1 to 1/99. Preferably, there is a formula (6) / formula (10) = 90/10 to 10/90, more preferably a formula (6) / formula (10) = 80/20 to 20/80. More preferably, formula (6) / formula (10) = 70/30 to 30/70 is particularly preferable.

If the structure represented by formula (6) is within 99, depending on the chemical structure of the R1 component, heat resistance and thermal dimensional accuracy are good. In addition, when the molar ratio of the structure represented by the formula (10) is within 99, depending on the R2 component and / or the R2 ′ component, low hygroscopicity and flexibility are generally improved. It also has good solubility.

To give an example of a method for producing a polyesterimide resin, a trimellitic anhydride halide and a diol are reacted to obtain an ester group-containing tetracarboxylic dianhydride, and then the ester group-containing tetracarboxylic acid dianhydride. It can be obtained by condensation reaction (polyimidation) of an anhydride with diamine or diisocyanate.

The molecular weight of the polyesterimide resin used in the present invention corresponds to a logarithmic viscosity at 30 ° C. in 0.1-2.5 dL / g in N-methyl-2-pyrrolidone (polymer concentration 0.5 g / dL). Those having a molecular weight are preferred, more preferably those having a molecular weight corresponding to 0.3 to 1.5 dL / g. If it is in the said range, mechanical characteristics will be enough, and the shaping | molding process at the time of processing to a film etc. will become easy.

[1.4] Polyamideimide The polyamideimide according to the present invention is an acid component,
a) Tricarboxylic 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, butan-1,2,4-tricarboxylic acid and other tricarboxylic acid monoanhydrides, esterified products and the like, or a mixture of two or more.

b) Tetracarboxylic acid; diphenylsulfone-3,3 ′, 4,4′-tetracarboxylic 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 compounds alone, or a mixture of two or more.

c) Dicarboxylic acid; adipic acid, azelaic acid, sebacic acid, dicarboxylic acid of cyclohexane-4,4'-dicarboxylic acid, and monoanhydrides and esterified products thereof.
As an amine component,
d) Amine component 3,3'-dimethyl-4,4'-diaminobiphenyl, 3,3'-diethyl-4,4'-diaminobiphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, 2 2,2'-diethyl-4,4'-diaminobiphenyl, 3,3'-dimethoxy-4,4'-diaminobiphenyl, 3,3'-diethoxy-4,4'-diaminobiphenyl, p-phenylenediamine, 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'-diaminobenzene Nzophenone, 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'-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, 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, tetramethylenediamine, hexamethylenediamine, isophoronediamine, 4,4'-dicyclohexylmethanediamine, cyclohexane-1,4-diamine, diaminosiloxane, or their corresponding diisocyanates These may be used alone or in combination of two or more.

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

The molar ratio between the imide bond and the amide bond of the polyamideimide is preferably 99/1 to 60/40, more preferably 99/1 to 75/25, and even more preferably 90/10 to 80/20. is there. When 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 one preferred embodiment, the unit represented by the formula (13) is an essential component, and at least one selected from the group represented by the formula (14), the formula (15), and the formula (16) is used. Is a polyamidoimide resin containing as a repeating unit in the molecular chain.

(X represents an oxygen atom, CO, SO ₂ , or a bond, and n represents 0 or 1.)

(Y represents an oxygen atom, CO, or OOC—R—COO, n represents 0 or 1, and R represents a divalent organic group.)

Here, in formula (14), SO ₂ or a bond (biphenyl bond) or n = 0 is preferable, and a bond (biphenyl bond) or n = 0 is more preferable. In formula (14), Y is preferably a benzophenone type (CO) or a bond type (biphenyl bond).

One preferred embodiment is that formula (13) is a repeating unit from trimellitic anhydride and 1,5-naphthalene diisocyanate, formula (14) is a repeating unit from terephthalic acid and 1,5-naphthalene diisocyanate, formula (15) Is a repeating unit from biphenyltetracarboxylic dianhydride and / or benzophenonetetracarboxylic dianhydride and 1,5-naphthalene diisocyanate, the content ratio of which is the formula (13) / {formula (14) + formula ( 15) + formula (16)} = 1/99 to 40/60 molar ratio, and formula (14) / formula (15) = 10/90 to 90/10 molar ratio is preferable.

The imide bond of the polyamide-imide resin preferably has an imidation ratio of 50% or more, more preferably 90% or more, and still more preferably 95% or more. The higher the imidization rate, the more preferable the upper limit is 100%. The polyamideimide resin can be synthesized by a usual method. For example, the isocyanate method, amine method (acid chloride method, low temperature solution polymerization method, room temperature solution polymerization method, etc.), etc., but the polyamideimide resin used in the present invention is preferably soluble in an organic solvent. For reasons such as ensuring the reliability of strength (adhesive strength), production by the isocyanate method is preferred. Also, industrially, it is preferable because the solution at the time of polymerization can be applied as it is.

The molecular weight of the polyamideimide resin of the present invention is a molecular weight corresponding to 0.3 to 2.5 dL / g in N-methyl-2-pyrrolidone (polymer concentration 0.5 g / dL) and logarithmic viscosity at 30 ° C. Those having a molecular weight corresponding to 0.5 to 2.0 dL / g are more preferable. When the logarithmic viscosity is 0.3 dL / g or more, mechanical properties are sufficient when formed into a molded product such as a film. On the other hand, if it is 2.0 dL / g or less, the solution viscosity does not become too high, and the molding process becomes easy.

[1.5] Polyetherimide The polyetherimide according to the present invention is a thermoplastic resin containing an aromatic nucleus bond and an imide bond in its structural unit, and is not particularly limited. It is a polyetherimide having a repeating unit represented by (17) or the following formula (18).

Polyetherimides having a repeating unit represented by the above formula (17) are trade names “Ultem 1000” (glass transition temperature: 216 ° C.) and “Ultem 1010” (glass transition temperature: 216 ° C.) manufactured by General Electric Co., Ltd. ], A polyetherimide having a repeating unit represented by the above formula (18) is “Ultem CRS5001” (glass transition temperature Tg 226 ° C.)], and other specific examples include products manufactured by Mitsui Chemicals, Inc. The name “Aurum PL500AM” (glass transition temperature 258 ° C.) and the like.

The method for producing the polyetherimide is not particularly limited. Usually, the amorphous polyetherimide having the above formula (17) is 4,4 ′-[isopropylidenebis (p-phenyleneoxy) diphthalate. As a polycondensate of acid dianhydride and m-phenylenediamine, and polyetherimide having the above structural formula (18), 4,4 ′-[isopropylidenebis (p-phenyleneoxy) diphthalic dianhydride It is synthesized by a known method as a polycondensate of benzene and p-phenylenediamine.

Further, the polyetherimide used in the present invention may contain other monomer units capable of copolymerization such as amide group, ester group and 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.

[2] Additives Various additives can be added to the dope containing the transparent heat-resistant resin having the imide structure according to the present invention. Additives that can be used are described below.

A heat conductive filler may be added to the dope containing the transparent heat resistant resin as long as the effect of the present invention is not impaired. Thereby, the thermal conductivity of a polyimide-type optical film can be raised.

The thermally conductive filler is preferably a highly thermally conductive filler, and specifically includes aluminum, copper, nickel, silica, diamond, alumina, magnesia, beryllia, boron nitride, aluminum nitride, silicon nitride, and silicon carbide. The filler shape is not particularly limited to a spherical or plate-like material, or a needle shape. Among these, at least one filler selected from silica, alumina, aluminum nitride, boron nitride, silicon nitride, and magnesia is preferable.

Further, a dehydrating agent may be added to the dope containing the transparent heat resistant resin according to the present invention. Specific examples of the dehydrating agent include aliphatic carboxylic acid anhydrides such as acetic anhydride, propionic anhydride and butyric anhydride, and aromatic carboxylic acid anhydrides such as benzoic anhydride, but acetic anhydride and / or anhydrous Benzoic acid is preferred. The content of the dehydrating agent relative to the polyamic acid or polyimide is preferably in the range where the dehydrating agent content (mole) / polyamic acid or polyimide content (mole) is 0.1 to 5.0. In this case, a gelation retarder such as acetylacetone may be used in combination.

Further, for example, a fluorine-based or polysiloxane-based surfactant may be added to the dope containing the transparent heat-resistant resin according to the present invention. When a surfactant is added, a film with good surface smoothness can be easily obtained. A commercially available product may be used as the surfactant, and examples of the fluorosurfactant include a mega-fac (registered trademark) series manufactured by DIC Corporation and a footer such as Neos Corporation's Footgent (registered trademark) series. GENT (registered trademark) 251, 212MH, 250, 222F, 212D, FTX-218, and the like. Examples of the polysiloxane surfactant include BYK-307, BYK-315, BYK-320, BYK-325, BYK-330, BYK-331, BYK-332, BYK-333, BYK manufactured by BYK-Chemie Japan Co., Ltd. -344 and the like.

Further, for example, a phenol-based, sulfur-based, phosphoric acid-based or phosphorous acid-based antioxidant may be added to the dope containing the transparent heat-resistant resin according to the present invention.

Various other functional materials may be added to the dope containing the transparent heat-resistant resin according to the present invention. Various functional materials include, for example, conductive materials such as carbon nanotubes and nano metal materials, ferroelectric materials such as barium titanate, and phosphors such as ZnS: Ag, ZnS: Cu, and Y ₂ O ₂ S: Eu. UV absorbers and the like.

Furthermore, a phosphorus flame retardant may be added to the dope containing the transparent heat resistant resin according to the present invention. Thereby, a flame retardance can be provided to a polyimide-type optical film. Examples of the phosphorus-based flame retardant include ammonium polyphosphate, phosphate ester, condensed phosphate ester, phenoxyphosphazene compound, phosphate ester amide, and the like. Among these phosphorus flame retardants, it is preferable to use a phenoxyphosphazene compound. As the phenoxyphosphazene compound, for example, SPS-100 manufactured by Otsuka Chemical Co., Ltd. can be used. Although a flame retardant can be imparted by mixing a halogen type flame retardant, it is preferable to use a phosphorus-based flame retardant.

[3] Imidization treatment of film When a cast film is formed using a polyamic acid, a polyimide film can be produced by applying an imidization treatment to the obtained film.

When the film is subjected to appropriate heat treatment, imidization in the polymer chain molecules and between the polymer chain molecules proceeds to improve the mechanical properties. However, as the heat treatment is performed, the optical film using polyimide changes in the absorption wavelength. The color changes with color. In particular, in an optical film using a polyimide with a thickness of 4.0 to 15.0 μm, the higher the L ^* value, the lighter the color, so that the horizontal unevenness due to thickness unevenness is less visible and the appearance is better. Since the progress of imidization is not sufficient, mechanical properties such as flex resistance and breaking strength of the polyimide film are deteriorated. On the other hand, if the L ^* value is too low, the color contrast due to the thickness unevenness becomes clear and the horizontal unevenness deteriorates, and the optical film using polyimide partially carbonizes and becomes brittle. Characteristics are significantly regressed. For the above reasons, in the method for producing an optical film using the polyimide of the present invention, an L ^* value of 30 to 55 is good for maintaining good mechanical properties, and more preferably, the L ^* value is 38 to 54 is preferable.

The L ^* value of the film was measured using SM-7-CH manufactured by Suga Test Instruments. About each sample divided into 5 in the film width direction, the range of 30 mm x 30 mm centering on the center position of the width direction was cut out and measured, and it was set as the 5-point average value. In addition, since the sensitivity of a detector becomes dull and the appropriate evaluation cannot be performed when the film thickness is thin, the L ^* value is one for a film having a thickness of 50 μm or more, and 50 μm or more for a film having a thickness of less than 50 μm. It is a value measured by overlapping the minimum number of sheets.

Regarding a heat treatment method for obtaining a film having an L ^* value of 30 to 55, for example, a method of adjusting the heat treatment amount using a known means such as hot air or an electric heater (for example, an infrared heater). Can be mentioned.

In the method for producing an optical film using the polyimide according to the present invention, a solution of a polyamic acid not containing a ring-closing catalyst and a dehydrating agent is cast, formed into a film, heated and dried on the support, and then from the support. A thermal ring closure method in which the film is peeled and further imidized by a drying heat treatment at a high temperature can be used. In addition, a solution of a polyamic acid containing a ring-closing catalyst and a dehydrating agent is cast to form a film, and after partially imidizing on the support to form a film, the film is peeled off from the support. Alternatively, a chemical ring closure method in which heat drying / imidization and heat treatment are performed can also be used. As the ring-closing catalyst, the above-mentioned tertiary amine or the like can be used.

In the thermal ring closure method, heat treatment can be performed by using, for example, an infrared heater.

As the infrared heater, for example, a heater main body formed so that a filament is surrounded by an inner tube is covered with an outer tube, and a cooling fluid can be circulated between the heater main body and the outer tube. The filament is energized and heated to 700 to 1200 ° C., and emits infrared light having a peak at a wavelength of about 3 μm. The inner tube and the outer tube are made of quartz glass, borosilicate crown glass, or the like, and function as a filter that passes infrared rays having a wavelength of 3.5 μm or less and absorbs infrared rays having a wavelength exceeding 3.5 μm. Such infrared heaters irradiate the film with infrared light having a wavelength of 3.5 μm or less through an inner tube or an outer tube when infrared light having a peak near 3 μm is emitted from the filament. By irradiating with infrared rays having this wavelength, the mixed solvent in the film can be efficiently evaporated and the polyamic acid in the film can be imidized. The inner tube and the outer tube absorb infrared rays having a wavelength exceeding 3.5 μm, but are cooled by the cooling fluid flowing through the flow path, so that the temperature can be maintained below the ignition point of the mixed solvent evaporating from the film. Is possible.

In the method for producing an optical film using the polyimide according to the present invention, any of the above ring closure methods may be adopted, but the chemical ring closure method requires equipment for containing a ring closure catalyst and a dehydrating agent in the polyamic acid solution. However, it can be said to be a more preferable method in that a film having self-supporting properties can be obtained in a short time.

[4] Method for Producing Optical Film Using Transparent Heat Resistant Resin Having Imide Structure A specific example of a method for producing a polyimide optical film (hereinafter also referred to as polyimide film) of the present invention will be described below.

A step of preparing a dope by dissolving the transparent heat-resistant resin having an imide structure according to the present invention in a mixed solvent containing 50% by mass or more of dichloromethane described later (dope preparation step), and flowing the dope onto a support. Extending the casting film to form a casting film (casting process), evaporating the solvent from the casting film on the support (solvent evaporation process), and peeling the casting film from the support (peeling process) A step of drying the obtained film (first drying step), a step of stretching the film (stretching step), a step of performing a bending treatment while further drying the stretched film (second drying step), and It is preferably performed by a step of winding a polyimide film (winding step), a step of heating the film to imidize (heating step), or the like.

Hereinafter, each process will be described in detail.

[4.1] Dope preparation step In the dope preparation step, the transparent heat-resistant resin having an imide structure according to the present invention is dissolved in dichloromethane as a main solvent, preferably a mixed solvent containing dichloromethane at 50% by mass or more of the solvent. It is preferable to prepare a new dope.

Thereafter, the prepared dope is guided to a filter by a liquid feed pump or the like and filtered.

That is, by filtering the dope at a temperature of boiling point at 1 atm of dichloromethane, which is the main solvent of the dope, at a temperature of 5 ° C. or higher, gel-like foreign matters in the dope are removed. A preferred temperature range is 45 to 120 ° C, more preferably 45 to 70 ° C, and even more preferably 45 to 55 ° C.

Here, it is preferable to use a solvent containing 50% by mass or more of dichloromethane from the viewpoint of improving the smoothness of the optical film.

The solvent contained together with dichloromethane may be any solvent that can dissolve the transparent heat-resistant resin having an imide structure according to the present invention, such as ethanol, butanol, N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-diethylacetamide, N, N-dimethylformamide, N, N-diethylformamide, N-methylcaprolactam, hexamethylphosphoramide, tetramethylenesulfone, dimethylsulfoxide, m-cresol, Phenol, p-chlorophenol, 2-chloro-4-hydroxytoluene, diglyme, triglyme, tetraglyme, dioxane, γ-butyrolactone, dioxolane, cyclohexanone, cyclopentanone, 1,4-dioxane, epsilon caprol Tam, chloroform and the like can be used, and may be used in combination of two or more. In addition to these solvents, a poor solvent such as hexane, heptane, benzene, toluene, xylene, chlorobenzene, or o-dichlorobenzene may be used to the extent that polyamic acid or polyimide does not precipitate.

Moreover, the solvent contained in the mixed solvent together with the dichloromethane is preferably a solvent having a boiling point higher than that of dichloromethane. Thereby, the curling of the cast film after peeling from the support can be effectively suppressed.

[4.2] Casting film forming step An endless support such as a stainless steel belt or a rotating metal that feeds the prepared dope to a die through a feed pump (for example, a pressurized metering gear pump) and transfers it infinitely A dope is cast from a die at a casting position on a metal support such as a drum.

The metal support in casting (cast) is preferably a mirror-finished surface, and the support is a stainless steel belt or a drum whose surface is plated with a casting, or a metal support such as a stainless steel belt or a stainless steel belt. Is 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, more preferably in the range of 2 to 2.8 m. Note that the support may not be made of metal.

The traveling 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, entrained gas is more likely to be generated, and the occurrence of film thickness unevenness due to disturbance is more pronounced.

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 not particularly limited, but is usually 0 ° C. or higher, preferably 20 to 60 ° C., more preferably 20 to 25 ° C.

The die has a shape that becomes gradually narrower toward the discharge port in the 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 portion of the die and 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.

Discharge rate of the dope from the die is preferably 200 ~ 720g / ^{m 2,} more preferably 400 ~ 650g / ^{m 2.} In the present invention, even when films having different thicknesses are continuously produced, it is preferable that the dope discharge amount from the die is maintained at a substantially constant value within the above range. When the discharge amount is 200 g / m ² or more, the cast film is not easily affected by disturbances such as vibration and wind, so that the film thickness unevenness can be sufficiently prevented. When the discharge amount is 720 g / m ² or less, the shrinkage does not occur excessively and the film thickness unevenness due to the contraction does not occur, and thus the film thickness unevenness can be sufficiently prevented.

[4.3] Solvent evaporation process The solvent evaporation process is a preliminary drying process in which a cast film (also referred to as a web) is heated on a 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 vary depending on the position. The temperature of the heating air is preferably 10 to 80 ° C.

In the method of heating the metal support, a higher temperature is preferable 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 planarity may deteriorate. Therefore, it is preferably performed at 10 to 30 ° C.

In the solvent evaporation step, it is preferable to dry the cast film until the residual solvent amount is 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 can be expressed by the following formula.

Residual solvent amount (% by mass) = {(MN) / N} × 100
Here, M is the mass at a predetermined point of the casting membrane (film), and 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.

[4.4] Peeling Step The cast film having the solvent evaporated on the metal support is peeled off at the peeling position.

The peeling tension when peeling the metal support from 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.

In the present invention, 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. Is most preferred.

The peeled film may be sent directly to the stretching process, or may be sent to the stretching process after being sent to the first drying process 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.

[4.5] 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., taking into account the amount of residual solvent and the stretching ratio during transportation.

[4.6] Stretching Step By stretching the film peeled from the metal support, the film thickness, flatness, orientation, etc. of the film can be controlled.

In the method for producing a polyimide film of the present invention, it is preferable to stretch in the longitudinal direction and / or the width direction.

The stretching operation may be performed in multiple stages. Moreover, when performing biaxial stretching, simultaneous biaxial stretching may be performed and you may implement in steps. 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.

Thus, for example, the following stretching steps are possible:
-Stretch in the longitudinal direction-> Stretch in the width direction-> Stretch in the longitudinal direction-> Stretch in the longitudinal direction-Stretch in the width direction-> Stretch in the width direction-> Stretch in the longitudinal direction-> Stretch in the longitudinal direction Includes stretching in one direction and contracting the other while relaxing the tension.

The residual solvent amount at the start of stretching is preferably in the range of 2 to 50% by mass.

If the amount of the residual solvent is 2% by mass or more, the film thickness deviation is small and is preferable from the viewpoint of flatness, and if it is within 10% by mass, the unevenness of the surface is reduced and the flatness is improved.

In the method for producing a polyimide film according to the present invention, the film may be stretched in the longitudinal direction and / or the lateral direction, preferably in the lateral direction so that the film thickness after stretching is in a desired range. The film is preferably stretched in a temperature range of (TgL−200) to (TgH + 50) ° C., where TgL is the lowest Tg of the glass transition point (Tg) and TgH is the highest Tg. 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 range of (TgL−150) to (TgH + 40) ° C.

In the method for producing a polyimide film of the present invention, the self-supporting film peeled from the support can be stretched in the longitudinal direction by regulating the running speed with a stretching roller. The draw ratio in the longitudinal direction is preferably 1.05 to 1.90 times, more preferably 1.10 to 1.60 times, still more preferably 1.10 to 1.50 times in a temperature range of 30 to 250 ° C. is there.

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 in 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 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 tenter clip. The draw ratio in the width direction is not particularly limited, but is preferably 1.05 to 1.90 times, more preferably 1.10 to 1.60 times, and still more preferably 1.10 to 1.000 in the temperature range of 30 to 300 ° C. 1.50 times.

When stretching in the width direction, stretching in the width direction of the film at a stretching speed 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 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.

More preferable stretching speed is in the range of 100 to 500% / min. The stretching speed is defined by the following formula.

Stretching speed (% / min) = [(d ₁ / d ₂ ) −1] × 100 (%) / t
(In the above formula, d ₁ is the width dimension in the stretching direction of the resin film after stretching, d ₂ is the width dimension in the stretching direction of the resin film before stretching, and 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 step may be performed at a temperature lower than the stretching temperature in the stretching step.

[4.7] Second drying step Subsequently, the stretched film is 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 more preferably in the range of 40 to 350 ° C. The drying time is preferably about 5 seconds to 30 minutes, more preferably 10 seconds to 15 minutes.

Further, the heating and drying means is not limited to hot air, and for example, infrared rays, heating rollers, microwaves, etc. can be used. The drying temperature is more preferably in the range of 40 to 350 ° C. in consideration of the residual solvent amount, the stretching ratio during conveyance, 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.

[Bending process]
In the second drying step in which the polyimide film of the present invention is dried in the dryer zone, the dryer zone has a drying temperature within the range of (glass transition temperature Tg-150) to (glass transition temperature Tg-30) ° C. of the film. If the bending process is performed 150 times or more while transporting the roller, the standard deviation σ of the gray scale is adjusted within a predetermined range, and the area occupied by the black portion in the binarized image is within the range of 10 to 50%. It is a preferable production method from the viewpoint of adjusting and improving the smoothness of the film.

The bending process is a B surface (for example, a casting support) that is opposed to the A surface (for example, the air surface side of the web on the casting support) of the web by a conveying roller while being held at a predetermined drying temperature. This is a process in which the belt is bent by a roller in the conveying process so that the belt surface side of the upper web is alternately inside. The bending process, when the radius when bending the web was a (mm), the value of 1 / a is in the range of 0.035 mm ^-1 ~ 0.050 mm ^-1, and 150 times the bending It is preferable that the drying is carried out by repeating the steps less than 500 times. Preferably, the number is in the range of 200 to 400 times in order to satisfy the effect of improving smoothness and productivity. The film folding interval is preferably in the range of 1 second to 1 minute, and more preferably in the range of 2 to 30 seconds.

The above bending process preferable for the present invention will be described with reference to the drawings. However, it is not limited to this.

FIG. 2 is a schematic diagram of a bending processing apparatus that can be preferably applied to the present invention.

A dope solution is cast from a die 101 onto a metal support 102 and continuously dried on the metal support by a driving roller 103 to obtain a web (referred to as a dope film after casting on the metal support. Form). The web is dried so that the residual solvent amount becomes a desired value, peeled into a film at the peeling point 104, subjected to preliminary drying and stretching treatment (not shown), conveyed to the bending zone 106, The transport roller 105 continuously conveys the A surface (the surface opposite to the surface where the web contacts the metal support) and the B surface (the surface where the web contacts the metal support) alternately inside the transport roller 105. The bending process is repeated. The bending process is performed in a bending zone 106 having an intake port 107 and an exhaust port 108, and is adjusted so that the film is bent at a desired atmospheric temperature. A cooling zone 109 for cooling the film to a predetermined temperature may be provided after the bending zone 106.

The diameter of the transport roller is preferably in the range of 90 to 108 mm, and the distance between the rollers is preferably about 1800 mm. The roller diameter may be determined so that the value of 1 / a is in the range of 0.035 to 0.050 mm ⁻¹ when the radius when the film is bent is a (mm).

In the bending zone 106, hot air whose temperature has been adjusted is introduced from the intake port 107, and the inside of the bending zone 106 is maintained at a constant atmospheric temperature and is exhausted from the exhaust port 108. In order to adjust the atmospheric temperature in the bending zone 106, it may be performed by infrared rays, a heating roller, or the like, but it is preferably performed by hot air in terms of simplicity. The atmosphere in the drying apparatus may be air, but may be performed in an inert gas atmosphere such as nitrogen gas, carbon dioxide gas, or argon.

The atmospheric temperature during the bending treatment of the polyimide film of the present invention is preferably carried out at a drying temperature within the range of (glass transition temperature Tg-150) to (glass transition temperature Tg-30) ° C. of the film. A range of 180 to 250 ° C. is more preferable for obtaining the effects of the present invention.

The conveyance speed of the polyimide film of the present invention in the bending zone is preferably 10 to 150 m / min, more preferably 15 to 100 m / min in terms of productivity and breakage.

[4.8] Winding step The winding step is a step of winding the obtained film and cooling it 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, a program tension control method with a constant internal stress, or the like.

The thickness of the film is not particularly limited, and is preferably 5 to 200 μm, particularly 5 to 100 μm.

In the winding process, both ends of the film sandwiched between tenter clips when stretched and conveyed may be slit. The slit end is preferably reused as a return material. Here, the recycled material refers to a portion that is formed into a film and is reused as a raw material for some reason, and the slit end (also referred to as an ear), or the feeding / termination of production. In addition, a film that is not suitable as a product due to an appearance problem such as a scratch or a streak is exemplified. The slit film edge is finely cut to a width of 1 to 30 mm, then dissolved in a solvent and reused.

The ratio of the portion of the formed film that is reused as a recycled material 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 return material generated during the film forming process or finally, but the mixing ratio of the returned material to the total solid content in the dope is usually about 10 to 50% by mass, preferably It is about 15 to 40% by mass. The mixing ratio of the recycled materials is preferably as constant as possible for production stability.

Each step 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, each process, especially a drying process and a extending process, are performed in consideration of the explosion limit concentration of the solvent in the atmosphere.

[4.9] Heating step After the winding step, the film dried in the second drying step is further heat-treated in order to improve imidization in the polymer chain molecules and between the polymer chain molecules to improve mechanical properties. It is preferable to perform the heating 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 For the purpose of relaxing, it is preferable to perform a heating step.

In addition, the said 2nd drying process may serve as a heating process.

The heating means is performed using a known means such as hot air, an electric heater, or a microwave. As the electric heater, the above-described infrared heater can be used.

The heat treatment conditions are such that the heater output and hot air temperature are adjusted so that the film L ^* value is 30 to 55, and the final treatment condition is within the temperature range of 200 to 450 ° C., and the range of 30 seconds to 1 hour. It is preferable to carry out as appropriate. 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, resulting in an increase in manufacturing cost and an increase in environmental load. 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 also good.

[5] Physical properties of polyimide optical film [5.1] Haze, total light transmittance The polyimide film of the present invention preferably has a haze of less than 1%, more preferably less than 0.5%. More preferably, it is less than 0.3%. By setting the haze to less than 1%, there is an advantage that the transparency of the film becomes higher and it becomes easier to use as a film for optical applications.

Using a haze meter (NDH2000 type, manufactured by Nippon Denshoku Industries Co., Ltd.) according to JIS K-7136, a film sample was conditioned for 24 hours at 23 ° C and 55RH air conditioning quality. The light transmittance is measured.

The total light transmittance is preferably 50% or more, more preferably 70% or more, and particularly preferably 85% or more from the viewpoint of providing the organic EL display with the optical film of the present invention. .

[5.2] Film Length, Width, Film Thickness The polyimide film according to the present invention is preferably long, specifically, preferably has a length of about 100 to 10,000 m and wound in a roll shape. Taken. The width of the polyimide film according to the present invention is preferably 1 m or more, more preferably 1.4 m or more, and particularly preferably 1.4 to 4 m.

The film thickness is preferably in the range of 5 to 200 μm from the viewpoint of strength and transparency, and more preferably in the range of 25 to 100 μm from the viewpoint of providing a thin film device. If the film thickness is 5 μm or more, a certain level of film strength can be developed. If the film thickness is 200 μm or less, flexibility can be exhibited.

[6] Organic electroluminescence display The organic EL display of the present invention preferably includes the polyimide optical film of the present invention. The polyimide optical film of the present invention has improved planarity, and When used on the surface, it is possible to provide an organic EL display that is not noticeably uneven when viewed through polarized sunglasses and has excellent visibility.

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 Patent Application Laid-Open No. 2014-017493, JP 20 It can be mentioned arrangement described in 4-017494 Patent Publication.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, although the display of "part" or "%" is used in an Example, unless otherwise indicated, "mass part" or "mass%" is represented.

Example 1
First, a method for producing the polyimide resin used in the examples will be described.

[Polyimide resin A: polyimide having a structure represented by the formula (1)]
(Polymerization of polyimide precursor)
Using a reactor equipped with a stainless separable flask as a reaction vessel, two paddle blades as a stirring device in the separable flask, and a device having a cooling capacity of 20.9 kJ / min as a cooling device A polyamic acid was produced. During the polymerization reaction, in order to prevent moisture from being mixed, the polymerization reaction was carried out by flowing nitrogen gas dehydrated by passing through silica gel at 0.05 L / min.

In the above separable flask, 223.5 g of N, N-dimethylformamide (DMF) is charged as a polymerization solvent, and 40.0 g (0.125 mol) of trifluoromethylbenzene (TFMB) is dissolved therein. To this solution, 55.5 g (0.125 mol) of 1,1,1,3,3,3-hexafluoro-2,2-di (3,4-dicarboxyphenyl) propane dianhydride (6FDA) Added and stirred to dissolve completely. After complete dissolution, the mixture was stirred to increase the polymerization viscosity to 80 Pa · s. The viscosity of the polyamic acid solution was kept for 1 hour in an aqueous solution kept at 23 ° C., and the viscosity at that time was measured with a B-type viscometer. 7 was measured at a rotational speed of 4 rpm. In addition, the preparation density | concentration of the aromatic diamine compound and aromatic tetracarboxylic dianhydride in this reaction solution is 30 mass% with respect to all the reaction liquids.

(Chemical imidation to polyimide resin)
DMF was added to the above solution to adjust the solid concentration to 15% by mass, and 60 g of pyridine (pkBH +; 5.17) as an imidization accelerator (molar ratio of imidization accelerator / amide group in polyamic acid = 3) was added. Disperse completely. To the dispersed solution, 30.6 g of acetic anhydride (dehydrating agent / molar ratio of amide group in polyamic acid = 1.2) was added at a rate of 1 g per minute and stirred for another 30 minutes. After stirring, the internal temperature was raised to 100 ° C. and superheated stirring was performed for 5 hours.

(Extraction of polyimide resin)
The polyimide resin solution was placed in a funnel having a hole diameter of about 5 mm and extracted by dropping in 5 L of methanol. At the time of extraction, extraction was performed while stirring methanol at high speed with a stirring blade rotated at 1500 rpm or more. The polyimide in the solution was hung in the methanol solution so that the diameter of the dripped polyimide solution was 1 mm or less near the methanol interface while adjusting the height between the funnel and the liquid surface of the methanol so as to form a fiber. The resin may be in a fibrous form, but by continuing stirring, what once becomes a fibrous form in the solution is decomposed and divided into fibers of 5 mm or less in the solution.

Further, 5 L of methanol was added to the divided resin solid solution, and the solid content was completely extracted and taken out. The solid content was washed with isopropanol in a Soxhlet extractor, and then 100 ° C. in a vacuum dryer. And dried as a polyimide resin.

[Synthesis of polyimide resin B: polyimide having repeating units represented by formulas (2) and (3)]
A 300 mL 5-neck separable flask equipped with a Dean-Stark apparatus equipped with a thermometer, a stirrer, a nitrogen inlet tube, and a condenser tube and a dropping funnel was charged with 4,4′-bis (4-aminophenoxy) biphenyl (BAPB). ) 26.48 g (0.07187 mol), γ-butyrolactone (GBL) 51.11 g, and triethylamine (TEA) 0.364 g were added and stirred under a nitrogen atmosphere to obtain a solution.

To this solution, 16.11 g (0.07187 mol) of 1,2,4,5-cyclohexanetetracarboxylic dianhydride (HPMDA) and 12.78 g of dimethylacetamide (DMAC) were added all at once, The reaction system was heated by a bath to raise the temperature inside the reaction system to 180 ° C. And the temperature in reaction system was maintained at 180 degreeC for 3.5 hours, collecting the component distilled off.

Next, after further adding 96.11 g of DMAC, the reaction system was stirred for about 30 minutes at a temperature in the vicinity of 130 ° C. to obtain a uniform solution. Got. The obtained polyimide solution was allowed to cool and then poured into methanol to precipitate a polyimide, and the precipitate was further washed and dried to obtain a polyimide resin solid.

[Synthesis of Polyimide Resin C: Polyesterimide]
41.3 g of diester tetracarboxylic dianhydride obtained by reacting trimellitic anhydride and 3,3 ′, 5,5′-tetramethyl-4,4′-biphenol as a diol compound in a reaction vessel. 07 mol), trimellitic anhydride 5.76 g (0.03 mol), diisocyanate 4,4'-diphenylmethane diisocyanate 25.03 g (0.1 mol), potassium fluoride 0.1 g, N-methyl After dissolving in 134.57 g of -2-pyrrolidone, the mixture was reacted at 80 ° C. to 190 ° C. for 8 hours with stirring in a nitrogen stream to obtain a transparent and viscous polyesterimide solution.

The polyesterimide solution was allowed to cool and then poured into methanol to precipitate the polyesterimide. This was again washed and dried to obtain a solid content of polyesterimide.

[Synthesis of Polyimide Resin D: Polyamideimide]
In a reaction vessel, 172 g of trimellitic anhydride (90 mol%, manufactured by Mitsubishi Gas Chemical Co., Ltd.), 29 g of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (10 mol%, Mitsubishi Chemical Corporation) 1,5-naphthalene diisocyanate 210 g (100 mol%, manufactured by Sumika Bayer Urethane Co., Ltd.), diazabicycloundecene 1 g (manufactured by San Apro), and N-methyl-2-pyrrolidone (NMP) ) 1836 g (Mitsubishi Chemical Corporation) (polymer concentration 15%) was added, the temperature was raised to 100 ° C. over 2 hours, and the reaction was allowed to proceed for 5 hours. Subsequently, NMP534g (polymer concentration 12 mass%) was added, and it cooled to room temperature.

The obtained polyamideimide solution was allowed to cool and then poured into methanol to precipitate polyamideimide. This was again washed and dried to obtain a solid content of polyamideimide.

[Preparation of polyimide resin E: polyetherimide]
The product name “Ultem 1000” manufactured by General Electric Co., Ltd. was used as the polyetherimide.

A polyimide film was prepared by the following method using the above polyimide resin.

<Preparation of polyimide film 101>
<Preparation of dope>
A main dope having the following composition was prepared. First, dichloromethane (MC) and ethanol (EtOH) were added to the pressure dissolution tank. The prepared polyimide resin A was added to a pressure dissolution tank containing a solvent while stirring. While this was heated and stirred, it was completely dissolved, and this was dissolved in Azumi Filter Paper No. After filtration using 244, the remaining components were added and stirred to dissolve to prepare the main dope.

<Composition of main dope>
Dichloromethane (abbreviated as MC in the table) 340 parts by mass Ethanol (abbreviated as EtOH in the table) 10 parts by mass Polyimide resin A 100 parts by mass <Casting step>
Next, using an endless belt casting apparatus, the dope was cast uniformly on a stainless steel belt support at a temperature of 30 ° C. and a width of 1500 mm. The temperature of the stainless steel belt was controlled at 30 ° C.

<Peeling process>
On the stainless steel belt support held at 40 ° C., the solvent was evaporated until the amount of residual solvent in the cast (cast) film reached 75%, and then from the stainless steel belt support at a peeling tension of 180 N / m. It peeled.

<Extension process>
The peeled polyimide film is 1.1 times in the MD direction (longitudinal direction) using the peripheral speed difference of the transport roller while applying heat at 200 ° C., and 1 in the TD direction (width direction) using a clip type tenter. The film was stretched 1 time. The residual solvent amount at the start of stretching was 20% by mass.

<Drying process>
The stretched film was subjected to bending processing 400 times by a large number of conveying rollers at a drying temperature of 220 ° C. in the bending zone 106 shown in FIG. The film was dried at a conveyance tension of 100 N / m and a drying time of 20 minutes so that the amount of residual solvent was less than 0.1% by mass to obtain a film having a dry film thickness of 80 μm. The obtained film was wound up to obtain a polyimide film 101.

<Preparation of polyimide films 102-105>
In the production of the polyimide film 101, polyimide films 102 to 105 were produced in the same manner except that the polyimide resins B to E were used instead of the polyimide resin A and the bending temperature was changed as shown in Table 1. did.

<Preparation of polyimide films 106-109>
In the production of the polyimide film 101, polyimide resins A to D are used, and γ-butyrolactone (indicated in the table as GBL) and dimethylacetamide (in the table as DMAc) are used as solvents, and stretching and bending treatments are performed. Comparative polyimide films 106 to 109 were produced in the same manner except that was not performed.

≪Evaluation≫
Using the produced polyimide films 101 to 109, the following evaluation was performed.

(1) Flatness evaluation Film projection images were analyzed using the apparatus and layout shown in FIG.

The white light source 2 is irradiated with the distance from the film sample 1 to the white light source 2 adjusted to 60 cm from an oblique 45 ° direction with respect to the film sample 1, and the distance from the film sample 1 to the projection plane 3 is projected to 70 cm. Camera 4 (Canon EOS KISS50, Lens EF-S 18 = 55 mm, ISO sensitivity 100, Aperture 5.6, Shutter speed 1/10 sec, White balance manual setting at a distance of 80 cm in the direction of 90 ° from the projection plane 3 ) And a projected image was photographed to obtain a photographed image.

Then, the standard deviation σ of the gray scale and the area ratio K (%) of the black part (dark part) of the binarized image were obtained for the photographed image by the following procedure.

1. The photographed image was read into a personal computer using free software ImageJ.

2. A rectangular evaluation area was set to be 1 cm × 5 cm in the actual captured image. At that time, the long side of the rectangle was set to be the film sample transport direction.

3. 8-bit conversion (gray scale conversion) was performed using free software ImageJ.

4. Background correction was performed with the free software ImageJ.

5. The standard deviation σ and the average value m of the gray value in the gray scale were calculated.

6. The rectangular evaluation area was binarized using the average value m as a threshold.

7. The area of the black part (dark part) obtained by the binarization was divided by the total area to calculate the black part area ratio K (%).

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

FIG. 4 shows a projected image, a binarized image, and a gray scale standard deviation of the polyimide optical film of the present invention for the polyimide film of the example. Further, projection images, binarized images, and gray scale standard deviations of the polyimide film of the comparative example are shown in FIGS.

(2) Visibility evaluation with polarized sunglasses Using the prepared polyimide films 101 to 109, the following visibility evaluation with polarized sunglasses was performed.

<Production of organic EL display>
Using the polyimide films 101 to 109 produced as described above, organic EL displays 101 to 109 were produced with the following configuration.

(Production of organic EL display)
An organic EL display having the configuration shown in FIG. 3 was produced.

[Production of organic EL display]
In the configuration shown in FIG. 3, a PET film is used as the transparent substrate 11, a reflective electrode made of chromium is formed thereon, a metal electrode 12 is formed on the reflective electrode using ITO as a metal electrode (anode), and the organic light emitting layer 13 is formed. As a hole transport layer, poly (3,4-ethylenedioxythiophene) -polystyrene sulfonate (PEDOT: PSS) is formed with a thickness of 80 nm on the anode by a sputtering method, and then a shadow mask is formed on the hole transport layer. In this way, RGB light emitting layers 13R, 13G, and 13B (all not shown) were formed to a thickness of 100 nm. As the red light emitting layer 13R, tris (8-hydroxyquinolinate) aluminum (Alq ₃ ) as a host and a light emitting compound [4- (dicyanomethylene) -2-methyl-6 (p-dimethylaminostyryl) -4H-pyran] ( DCM) were co-evaporated (mass ratio 99: 1) to form a thickness of 100 nm. As the green light emitting layer 13G, Alq ₃ as a host and the light emitting compound coumarin 6 (3- (2-benzothiazolyl) -7- (diethylamino) coumarin) are co-evaporated (mass ratio 99: 1) to a thickness of 100 nm. Formed. The blue light emitting layer 13B was formed with a thickness of 100 nm by co-evaporating BAlq and a light emitting compound Perylene as a host (mass ratio 90:10).

Further, calcium is deposited in a thickness of 4 nm by vacuum deposition as a first cathode having a low work function so that electrons can be efficiently injected onto the organic light emitting layer, and a second cathode is formed on the first cathode. As a result, aluminum was formed to a thickness of 2 nm. Here, the aluminum used as the second cathode has a role to prevent calcium as the first cathode from being chemically altered when the transparent conductive film formed thereon is formed by sputtering. . As described above, an organic light emitting layer was obtained. Next, a transparent conductive film was formed to a thickness of 80 nm on the cathode by sputtering to form a transparent electrode 14. Here, ITO was used as the transparent conductive film. Furthermore, 200 nm of silicon nitride was deposited on the transparent electrode 14 by the CVD method to form the insulating film 15 and an organic EL element unit was fabricated.

Next, a polyethylene terephthalate film with a gas barrier layer having a thickness of 20 μm is used as the gas barrier film 17, and a thermosetting liquid adhesive (epoxy resin) is used as the sealing layer 16 on one side of the gas barrier film 17. A sealing unit having a thickness of 25 μm was produced.

Next, the organic EL element unit formed from the transparent substrate 11 to the insulating layer 15 and the sealing unit were pressed and held for 5 minutes under a reduced pressure of 0.1 MPa at 90 ° C. Subsequently, the laminate was returned to the atmospheric pressure environment, and further heated at 90 ° C. for 30 minutes to cure the adhesive, whereby an organic EL display device B was produced.

The light-emitting area of the produced organic EL display device B was 1296 mm × 784 mm. Further, the front luminance when a DC voltage of 6 V was applied to the organic EL display device B was 1200 cd / m ² . The front luminance is measured using a spectral radiance meter CS-1000 manufactured by Konica Minolta Co., Ltd., with the front luminance at 2 ° viewing angle and the optical axis of the spectral radiance meter aligned with the normal from the light emitting surface. The range of visible light wavelength of 430 to 480 nm was measured, and the integrated intensity was taken.

[Production of organic EL displays 101 to 109]
A circularly polarizing plate C on which the λ / 4 retardation film 18, the polarizer 19, and the protective film 20 are mounted on the produced organic EL display device B so as to face each other so as to have the configuration shown in FIG. 3. Further, the polyimide films 101 to 109 produced as the upper layer were laminated as the outermost layer 21b as the front plate 21 via the adhesive layer 21a to produce the organic EL displays 101 to 109.

<Visibility evaluation using polarized sunglasses>
The produced organic EL displays 101 to 109 are observed through polarized sunglasses. The display unevenness at that time was visually evaluated by 10 observers in the following five stages. For practical use, 4 or more is not a problem.

5: It is determined that display unevenness is not conspicuous for all 10 observers. 4: 8 observers determine that display unevenness is not conspicuous. 3: 5 observers determine that display unevenness is conspicuous. 2: 8 observers. Determines that display unevenness is conspicuous 1: All observers determine that display unevenness is conspicuous

From Table 1, the polyimide films 101 to 105 made of polyimide resin by the preferred production method of the present invention have the gray scale standard deviation σ and the area ratio of the black portion of the binarized image within the range defined by the present invention. When the organic EL display using the same was observed with polarized sunglasses, it was found that display unevenness was not noticeable and visibility was good.

Example 2
<Preparation of polyimide films 201-204>
In the production of the polyimide film 101 of Example 1, polyimide films 201 to 204 were produced in the same manner except that the number of bending treatments was changed as shown in Table 2.

The same evaluation as in Example 1 was performed using the produced polyimide films 201 to 204.

In the preferable manufacturing method of the present invention, when the preferable temperature and number of bending processes are satisfied, the grayscale standard deviation σ and the area ratio of the black portion of the binarized image satisfy the range defined in the present invention, and It was found that when the organic EL display using was observed with polarized sunglasses, display unevenness was not noticeable and visibility was good.

Example 3
<Preparation of polyimide films 301 to 304>
Polyimide films 301 to 304 were produced in the same manner as in the production of the polyimide film 101 of Example 1, except that the draw ratio was changed as shown in Table 3.

The same evaluation as in Example 1 was performed using the produced polyimide films 301 to 305.

In the preferred production method of the present invention, when stretching at a preferred stretch ratio, the grayscale standard deviation σ and the area ratio of the black portion of the binarized image satisfy the range defined in the present invention and used. When the organic EL display was observed with polarized sunglasses, it was found that display unevenness was not noticeable and visibility was good.

Example 4
<Preparation of polyimide films 401-404>
Polyimide films 401 to 404 were produced in the same manner as in the production of the polyimide film 101 of Example 1, except that the film thickness was changed as shown in Table 4.

The same evaluation as in Example 1 was performed using the produced polyimide films 401 to 404.

In the preferred production method of the present invention, when produced with a preferred film thickness, the grayscale standard deviation σ and the area ratio of the black portion of the binarized image satisfy the range defined in the present invention and used. When the organic EL display was observed with polarized sunglasses, it was found that display unevenness was not noticeable and visibility was good.

The polyimide-based optical film of the present invention has improved flatness, and when used on the surface of an organic electroluminescence display, the unevenness of the film when viewed through polarized sunglasses is not noticeable and has excellent visibility. It can be suitably used as a display application.

DESCRIPTION OF SYMBOLS 1 Polyimide type optical film 2 White light source 3 Projection surface 4 Camera A Organic EL display B Organic EL display device C Circular polarizing plate 11 Substrate, transparent substrate 12 Metal electrode 13 Organic light emitting layer 14 Transparent electrode 15 Insulating layer 16 Sealing layer 17 Gas Barrier film 18 λ / 4 retardation film 19 Polarizer 20 Protective film 21 Polyimide film 21a Polyimide film 21b Adhesive layer 100 Die 102 Metal support 103 Driving roller 104 Peeling point 105 Conveying roller 106 Bending zone 107 Air inlet 108 Air outlet 109 Cooling zone

Claims

A polyimide optical film containing a transparent heat resistant resin having an imide structure,
In a predetermined rectangular area cut out from the projected image of the polyimide optical film, the standard deviation σ of the gray scale is in the range of 0.50 to 1.10, and the black portion in the binarized image of the rectangular area The polyimide-based optical film is characterized in that the area occupied by is adjusted to 50% or less.
The transparent heat resistant resin having the imide structure is a polyimide having a structure represented by the formula (1), a polyimide having a structure represented by the formula (2) or the formula (3), a polyesterimide, a polyamideimide, and a polyether. The polyimide-based optical film according to claim 1, wherein the polyimide-based optical film is selected from imides.

(In the formula (3), X is a divalent aliphatic group having 2 to 39 carbon atoms, a divalent alicyclic group having 3 to 39 carbon atoms, or a divalent aromatic group having 6 to 39 carbon atoms. A divalent group consisting of a group or a combination thereof, and the main chain of X includes —O—, —SO 2 —, —CH 2 —, —C (CH 3 ) 2 —, —OSi (CH 3 ) At least one linking group selected from the group consisting of 2 —, —C 2 H 4 O— and —S— may be interposed, and X is selected from the group consisting of a carboxy group, a hydroxy group or a carbonyl group. And may have at least one functional group.)
A method for producing a polyimide optical film for producing the polyimide optical film according to claim 1, wherein a dope containing the transparent heat-resistant resin having the imide structure and dichloromethane is prepared, and a solution flow is prepared. A method for producing a polyimide-based optical film, wherein the film is formed by a film-forming method.
In the film forming process, the film is stretched at a magnification of 1.05 times or more in at least one direction of the longitudinal direction or the width direction, and then the (glass transition temperature Tg-150) to (glass transition temperature Tg-30) of the film. The method for producing a polyimide-based optical film according to claim 3, wherein the bending treatment is performed 150 times or more while being conveyed by a roller at a drying temperature in a range of ° C.
5. The method for producing a polyimide-based optical film according to claim 3, wherein the film thickness is adjusted within a range of 25 to 100 μm.
An organic electroluminescence display comprising the polyimide-based optical film according to claim 1.