JP2017187617A - Method of manufacturing optical film, and manufacturing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing an optical film principally made of a polyimide resin, which reduces scaly irregularity that may be caused when separating a casting film from a film-forming support body.SOLUTION: An optical film manufacturing method of the present invention involves forming a casting film by casting dope containing a soluble polyimide resin as a principal component and dichloromethane as a principal solvent onto a film-forming support body, the dope having a solution haze of 1.0% or less, and includes a step of feeding a polar solvent to a boundary surface between the casting film and the film-forming support body.SELECTED DRAWING: None

Description

  The present invention relates to a method and an apparatus for producing an optical film, and more specifically, an optical film mainly composed of a polyimide resin, which reduces scaly unevenness that occurs when a casting film is peeled from a film-forming support. The present invention relates to a film manufacturing method and a manufacturing apparatus.

  A general-purpose polyimide film is generally formed by casting a dope containing a polyamic acid on a belt or a drum and subjecting the polyamic acid to an imidization reaction such as heating to form a solution casting film (for example, a patent Reference 1). However, general-purpose polyimides are strongly colored when imidized, and cannot be applied to optical films that require transparency and non-colorability as they are.

  Taking advantage of the high heat resistance characteristics of polyimide film, we tried to produce high heat resistance and high transparency polyimide film by solution casting film using solvent-soluble and transparent polyimide resin for application to optical film. As a result, scaly unevenness at the time of peeling, which was not a problem in the production of a general-purpose polyimide film, occurred, and sufficient quality for use as an optical film could not be obtained.

  As a result of diligent investigation of this problem, in the process of forming a general-purpose polyimide resin, the casting film (also referred to as web) contracts due to the imidization reaction on the film-forming support, and at the same time, water precipitates due to the reaction. For this reason, the separation between the casting membrane and the film-forming support was easy, whereas when a soluble and transparent polyimide resin was used, the imidization reaction on the belt occurred. Therefore, there is no shrinkage of the casting film and no precipitation of water, so that peeling between the casting film and the film-forming support becomes difficult, and as a result, the scaly unevenness occurs due to peeling force. I found.

  Patent Document 2 includes a polyamic acid having a specific structure and two or more kinds of mixed solvents selected from a water-soluble ether compound, a water-soluble ketone compound, a water-soluble alcohol compound, and water, or an ether group in the same molecule. Although a method for preparing a polyimide film by preparing a polyamic acid solution with a compound having an alcoholic hydroxyl group and casting it on a substrate is disclosed, when the casting film is peeled off from the film-forming support No mention is made of the scaly unevenness that occurs in.

JP 2010-1000067 A Japanese Patent Laid-Open No. 10-195295

  The present invention has been made in view of the above-mentioned problems and situations, and its solution is to solve the problem of a soluble polyimide resin with reduced scaly unevenness that occurs when the casting film is peeled off from the film-forming support. It is providing the manufacturing method and manufacturing apparatus of the optical film which makes a main component.

  In order to solve the above-mentioned problems, the present inventor has cast a dope containing a soluble polyimide resin as a main component and dichloromethane as a main solvent on a film-forming support in the process of examining the cause of the above-mentioned problem. An optical film having a step of supplying a polar solvent to an interface between the casting film and the film-forming support, wherein the dope solution haze is 1.0% or less when forming the casting film. It has been found that a method for producing an optical film with reduced scaly unevenness can be provided by the production method.

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

1. A method for producing an optical film comprising a soluble polyimide resin as a main component and casting a dope containing dichloromethane as a main solvent on a film-forming support,
The solution haze of the dope is 1.0% or less, and
A method for producing an optical film, comprising a step of supplying a polar solvent to an interface between the casting film and the film-forming support.

2. The dope contains an alcohol solvent as an auxiliary solvent so that the alcohol mass ratio in the total solvent is 3.0% or less, and
2. The method for producing an optical film according to claim 1, wherein the step of supplying the polar solvent is a step of exposing the cast film in an atmosphere of water or an alcohol solvent.

3. The dope contains an alcohol solvent as an auxiliary solvent so that the alcohol mass ratio in the total solvent is 3.0% or less, and
Item 1 is characterized in that the step of supplying the polar solvent is a step of spraying water or an alcohol solvent on the casting film or immersing the casting film in the water or alcohol solvent. The manufacturing method of the optical film of description.

4). The dope contains an alcohol solvent as an auxiliary solvent so that the alcohol mass ratio in the total solvent exceeds 3.0%, and
2. The method for producing an optical film according to item 1, wherein the step of supplying the polar solvent is a step of containing water in the dope.

5. An apparatus for producing an optical film comprising a soluble polyimide resin as a main component and casting a dope containing dichloromethane as a main solvent on a film-forming support to form a cast film,
The solution haze of the dope is 1.0% or less, and
An apparatus for producing an optical film, comprising: a polar solvent supply unit that supplies a polar solvent to an interface between the casting film and the film-forming support.

  Provided is a method and an apparatus for producing an optical film mainly composed of a polyimide resin, in which scaly unevenness that occurs when a casting film is peeled from a film-forming support by the above-described means of the present invention is reduced. Can do.

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

  In the present invention, when forming a cast film by casting a dope containing a soluble polyimide resin as a main component and dichloromethane as a main solvent on a film-forming support, the dope solution haze is 1.0. %, And by supplying a polar solvent to the interface between the casting membrane and the film-forming support, water that has been precipitated by the imidation reaction while ensuring transparency that can be used as an optical film. In addition to producing the same effect as above, the polar solvent acts as a poor solvent on the polyimide resin dope, which can also cause shrinkage of the cast film, resulting in reduced peeling force at the interface and transparent optical film applications. It is presumed that the scaly unevenness, which is a problem when used as a solution, could be solved.

Sectional drawing which shows the schematic structure of the manufacturing apparatus used for manufacture of the polyimide film which concerns on embodiment of this invention. Schematic diagram of exposure device for polar solvent added to cast film forming part Schematic diagram of polar solvent spraying device and dipping device to be added to cast film forming part or peeling part Sectional drawing which shows the detailed structure of the 1st extending | stretching apparatus with which the said manufacturing apparatus is equipped. Sectional drawing which shows the other structure of the said 1st extending | stretching apparatus. Sectional drawing which shows typically the example of arrangement | positioning of the upstream and downstream roller of the said 1st extending | stretching apparatus. Sectional drawing which shows typically the other example of arrangement | positioning of the roller of the upstream of the said 1st extending | stretching apparatus, and a downstream. Sectional drawing which shows the other structural example of the roller of the upstream of the said 1st extending | stretching apparatus.

  The method for producing an optical film of the present invention is a method for producing an optical film in which a dope containing a soluble polyimide resin as a main component and dichloromethane as a main solvent is cast on a film-forming support to form a cast film. The dope has a solution haze of 1.0% or less and a step of supplying a polar solvent to the interface between the cast film and the film-forming support. This feature is a technical feature common to or corresponding to the claimed invention.

  As an embodiment of the present invention, from the viewpoint of expression of the effect of the present invention, the dope contains an alcohol solvent as an auxiliary solvent so that an alcohol mass ratio in the total solvent is 3.0% or less, and In the step of supplying the polar solvent, exposing the cast film in water or an alcohol solvent atmosphere has the same effect as water precipitated in the imidization reaction, and the polar solvent is a poor solvent. By acting on the polyimide resin dope and causing shrinkage of the cast film, it is preferable from the viewpoint of reducing the peeling force at the interface and reducing scaly unevenness.

  The dope contains an alcohol solvent as an auxiliary solvent so that an alcohol mass ratio in the total solvent is 3.0% or less, and the step of supplying the polar solvent includes water or an alcohol solvent. Spraying the casting film or immersing the casting film in the water or an alcohol-based solvent has the same effect as the water precipitated in the imidization reaction, and the polar solvent is a poor solvent. It is preferable from the viewpoint of reducing peeling force at the interface and reducing scaly unevenness by causing shrinkage of the cast film by acting on the resin dope.

  The dope contains an alcohol solvent as an auxiliary solvent so that the alcohol mass ratio in the total solvent exceeds 3.0%, and the step of supplying the polar solvent includes water in the dope. This has the same effect as water precipitated by imidization reaction without requiring a special device, and also causes contraction of the cast film by the polar solvent acting on the polyimide resin dope as a poor solvent. This is preferable from the viewpoint of reducing peeling force at the interface and reducing scaly unevenness.

  The optical film manufacturing apparatus of the present invention is an optical film manufacturing apparatus that forms a cast film by casting a dope containing a soluble polyimide resin as a main component and dichloromethane as a main solvent on a film-forming support. In addition, it is preferable that the dope has a solution haze of 1.0% or less and a polar solvent supply unit that supplies a polar solvent to an interface between the casting film and the film-forming support.

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

<< Outline of Manufacturing Method of Optical Film of the Present Invention >>
The method for producing an optical film of the present invention is a method for producing an optical film in which a dope containing a soluble polyimide resin as a main component and dichloromethane as a main solvent is cast on a film-forming support to form a cast film. A method for producing the dope, wherein the dope has a solution haze of 1.0% or less, and a step of supplying a polar solvent to an interface between the casting film and the film-forming support. Thus, the present invention provides a method for producing an optical film containing a soluble polyimide resin as a main component, in which scaly unevenness generated when the cast film is peeled off from the support is reduced.

  The optical film of the present invention contains a soluble polyimide resin as a main component. The “main component” means that the total amount of polyimide resin is 50% by mass or more with respect to the total amount of resin constituting the optical film. It is preferably 80% by mass or more, particularly preferably 90% by mass or more.

  The soluble polyimide resin according to the present invention is defined as a polyimide resin that dissolves 1 g or more in 100 g of dichloromethane at 25 ° C.

  In addition, the dope according to the present invention is a dope containing dichloromethane as a main solvent, and the “main solvent” means that the content in the total solvent is 55% by mass or more. , Preferably 70% by mass or more, more preferably 80% by mass or more.

  The solution haze according to the present invention serves as an index of transparency of the optical film after film formation. If the solution haze is 1% or less, transparency as an optical film can be secured even after film formation. The soluble polyimide resin and other additives used in the production method of the present invention are made with dichloromethane as a main solvent, and after adding an auxiliary solvent as necessary, a dope is prepared, and then the dope is compliant with JIS K 7136. The haze was measured with a haze meter NDH-2000 (manufactured by Nippon Denshoku Industries Co., Ltd.). Specifically, measurement is performed under the conditions of 23 ° C., 55% RH, and optical path length of 1 cm. The light source of the haze meter is a halogen bulb of 5 V and 9 W, and the light receiving part is a silicon photocell (with a relative visibility filter). The haze of the dope is measured.

  The present invention is characterized by supplying a polar solvent to the interface between the casting membrane and the film-forming support, shrinking the casting membrane, and reducing the peeling force by allowing the polar solvent to exist at the interface. However, the “shrinkage” of the casting film means the width of the casting film on the film-forming support when the dope is solution-cast on the film-forming support to form the casting film. A state in which the hand length contracts by 1% or more as a contraction rate represented by the following formula.

As the cast film sample for measuring the width, the cast film 10 seconds after the dope was cast on the film-forming support was sampled in the width direction as the L ₀ measurement sample, and the cast film was measured. after the casting film immediately before the peeling from the film for support is taken in the width direction as a sample for L ₁ measured, collected samples were each allowed to stand for 1 hour under an environment of 25 ℃ · 55% RH, respectively Measure the lateral length of the.

(Expression) Shrinkage rate (%) = (L ₀ −L ₁ ) / (L ₀ ) × 100
(In the formula, L ₀ is a cast film formed by casting a dope on a film-forming support to form a cast film 10 seconds later, and L ₁ is the cast film. (This refers to the width of the cast film just before peeling off from the film support.)
The “polar solvent” is classified into a protic polar solvent and an aprotic polar solvent. Examples of the protic polar solvent include water, ethanol, acetic acid, and the like. Examples include acetonitrile and acetone.

  In addition, the optical film manufactured by the manufacturing method of the optical film of this invention may be simply called a polyimide film.

[1] Manufacturing method and manufacturing apparatus of optical film The manufacturing method of the optical film of the present invention includes a step of preparing a dope containing the soluble polyimide resin as a main component and dichloromethane as a main solvent (dope preparation step), the dope Forming a cast film on the support (casting process), evaporating the solvent from the cast film on the support (solvent evaporation process), peeling the cast film from the support A step of performing (peeling step), a step of stretching the peeled cast film (stretching step), a step of drying the stretched film (drying step), a step of winding up the obtained optical film (winding step), Furthermore, if necessary, it is preferable to include a step of heating the film to imidize it (heating step).

  The “step of supplying a polar solvent to the interface between the casting membrane and the film-forming support” according to the present invention is at least the dope preparation step, the casting step, the solvent evaporation step, or the peeling step. Preferably there is.

[1.1] Optical film manufacturing apparatus The optical film manufacturing apparatus of the present invention includes a dope preparation unit for preparing a dope containing the soluble polyimide resin as a main component and dichloromethane as a main solvent, and the dope on a support. A casting film forming part for casting a film on the support, a solvent evaporation part for evaporating the solvent from the casting film on the support, a peeling part for peeling the casting film from the support, a peeled flow It is preferable to include a stretching unit for stretching the stretched film, a drying unit for drying the stretched film, and a winding unit for winding the obtained optical film.

  A feature of the production apparatus of the present invention is that it has a polar solvent supply unit that supplies a polar solvent to an interface between the casting membrane and the film-forming support, and the polar solvent supply unit includes at least the dope preparation. Part, the cast film forming part, the solvent evaporation part, or the peeling part.

  FIG. 1 is a cross-sectional view showing a schematic configuration of a manufacturing apparatus 1 used for manufacturing the optical film of the present embodiment. The manufacturing apparatus 1 is an example, and the present invention is not limited to this. The first extending unit 3 and the second extending unit 4 shown in the manufacturing apparatus 1 may also serve as the same.

  The manufacturing apparatus 1 includes a casting film forming unit 2, a first stretching unit 3, a second stretching unit 4, a drying unit 5, and a winding unit 6, and is formed by the casting film forming unit 2. While transporting the casting film (web) 22, the first stretching section 3 stretches in the MD (casting) direction or TD (width) direction, and the second stretching section 4 additionally stretches in the MD direction or TD direction. Then, it is dried (heat treated) in the drying unit 5 and wound up as the optical film F in the winding unit 6. The cast film 22 is a film formed by casting a resin solution (dope) containing a resin and a solvent on a traveling support and drying it. Note that a drying unit may be disposed between the first stretching unit 3 and the second stretching unit 4 to dry the casting film 22.

(Casting film forming part)
The cast film forming unit 2 includes an endless belt 11 as a support, a die 12, a heating unit 13, and a peeling roller 14.

  The endless belt 11 is a metal belt having a mirror-finished surface. As such a belt, for example, a stainless steel whose surface is mirror finished or a metal endless belt whose surface is plated with a casting is used. The endless belt 11 is wound around a driving roller 11a and a driven roller 11b, and can travel in the direction of an arrow in the figure. The width of the endless belt 11 varies depending on the size of the optical film to be manufactured, but is preferably in the range of 1700 to 2700 mm, for example. And the width | variety which casts the dope 21 has the preferable range of 80 to 99% among the width | variety of the endless belt 11, for example. In place of the endless belt 11, a metal cylindrical drum having a mirror-finished surface may be used as the film-forming support.

  The die 12 casts the dope 21 on the endless belt 11. The heating unit 13 is provided to heat the dope 21 (cast film 22) cast on the endless belt 11 and reduce the solvent contained in the dope 21 (cast film 22). Details thereof will be described later. The peeling roller 14 is provided for peeling the casting film 22 formed on the endless belt 11 from the endless belt 11.

  The casting film forming unit 2 includes a casting process of casting a dope 21 containing a resin and a solvent on the endless belt 11 as a traveling support to form a casting film 22 and a solvent. In the state, a peeling step of peeling the casting film 22 from the endless belt 11 is performed.

  In the casting process, the dope 21 is cast on the endless belt 11 from the die 12 and dried by the heating unit 13. As a result, the dope 21 is dried and gelated on the endless belt 11 to form a cast film 22.

  The thickness of the casting film 22 on the endless belt 11 can be changed to various values so that the thickness of the optical film wound up by the winding unit 6 becomes a predetermined thickness. Is adjusted according to the casting amount of the belt, the traveling speed of the endless belt 11, and the like.

  In the peeling step, the casting film 22 formed on the endless belt 11 is peeled from the endless belt 11 by the peeling roller 14.

  The time from casting the dope 21 onto the endless belt 11 to peeling the casting film 22 from the endless belt 11 varies depending on the thickness of the manufactured optical film, the type of solvent, etc. Considering good peelability from the belt 11, for example, a range of 0.5 to 5 minutes is preferable.

  Further, the tension (peeling tension) acting on the casting film 22 when the casting film 22 is peeled from the endless belt 11, and the tension (transporting) acting on the casting film 22 when the casting film 22 is transported after peeling. Due to the tension), the casting film 22 is stretched in the MD direction. In consideration of this, the above-described peeling tension and conveying tension are preferably in the range of 20 to 400 N / m, for example.

  Next, the heating unit 13 will be described. The heating unit 13 heats the casting film 22 with heating air to remove the solvent, and includes a drying box 31, a first heating air supply unit 32 and a second heating air supply provided in the drying box 31. A portion 33 and an exhaust port 34 are provided. The first heating air supply unit 32 and the second heating air supply unit 33 include heating air supply pipes 32a and 33a and headers 32b and 33b, respectively, and the endless belt 11 is transported in the transport direction of the casting film 22. It is arranged so as to be sandwiched from above and below in the vertical direction.

  The temperature of the casting film 22 on the endless belt 11 on the first heating air supply unit 32 side and the temperature of the casting film 22 on the endless belt 11 on the second heating air supply unit 33 side are respectively responsible for the evaporation of the solvent. Considering the traveling speed of the endless belt 11 determined based on the time required, and when the fine particles are added to the dope 21, the range of −5 to 70 ° C. is preferable in consideration of the degree of dispersion of fine particles, productivity, and the like. The range of 0-60 degreeC is more preferable.

  The wind pressure of the heating air supplied from the first heating air supply unit 32 and the second heating air supply unit 33 is, for example, 50 to 50 in consideration of the uniformity of evaporation of the solvent, the degree of dispersion of the fine particles in the dope 21, and the like. A range of 5000 Pa is preferred.

  The first heating air supply unit 32 and the second heating air supply unit 33 may supply only the heating air having a constant temperature, or stepwise the heating air having a plurality of temperatures along the traveling direction of the endless belt 11. You may supply.

  The heating unit 13 is not limited to the one that heats the casting film 22 with heating air as described above. For example, the heating part 13 heats the casting film 22 with an infrared heater, or blows heating air on the back surface of the endless belt 11. What casts the casting film 22 from the back surface etc. may be used.

<Polar solvent supply unit>
The polar solvent supply unit according to the present invention is preferably included in at least the dope preparation unit, the cast film formation unit, the solvent evaporation unit, or the peeling unit.

  In particular, in the present invention, the casting film forming unit 2 is water or alcohol as a polar solvent supplying unit that supplies a polar solvent to a part of the endless belt 11 at the interface between the casting film and the film-forming support. It is preferable to have a gas exposure apparatus that exposes the cast film in a system solvent atmosphere (gas).

  An example of the gas exposure apparatus which exposes the said cast film in the said water or alcohol solvent atmosphere is shown in FIG.

  FIG. 2 is a schematic view of a polar solvent gas exposure apparatus added to the cast film forming section. This figure is an example, and the present invention is not limited to this. The installation position of the gas exposure device can be set as appropriate in the casting process.

  A polar solvent gas exposure device 35 is installed adjacent to the second heating air supply unit 33, and a slit (not shown) is provided in the gas exposure device 35 so that the casting film 22 can pass through the gas exposure device. ). The gas exposure device 35 has a polar solvent gas supply pipe 35a on one side and a polar solvent gas exhaust port 35b on the other side, and a monitor and pump (not shown) so that the gas concentration of the polar solvent is constant. The gas circulates in the gas exposure device 35 while being controlled by.

  The polar solvent can be supplied to the interface between the casting film 22 and the endless belt 11 by passing the casting film 22 through the gas exposure device 35 in which the gas concentration is controlled to be constant. The adjustment of the supply amount is preferably set as appropriate by monitoring the degree of contraction of the above-described casting film or measuring the content of the polar solvent in the casting film immediately after peeling described later.

  It is preferable to control the temperature of the polar solvent gas in addition to the gas concentration, and it is preferable to set the temperature appropriately by monitoring the degree of shrinkage of the cast film.

  The specification of the gas exposure apparatus as an example is as follows.

(Gas exposure device)
Case size: Width; casting film width + set within 100 mm, length: 100-1000 mm, height: 10-500 mm
Gas pressure control: 10 to 2000 Pa
Gas temperature control: 0-80 ° C
Casting film passage time: 1 second to 10 minutes In addition, the step of supplying the polar solvent is to spray water or an alcohol solvent on the casting film or immerse the casting film in the water or alcohol solvent. It is preferable to have a device that performs the above.

  FIG. 3 shows an example of an apparatus for spraying the water or alcohol solvent or immersing the cast film in the water or alcohol solvent.

  FIG. 3 is a schematic view of a polar solvent spraying device and a dipping device to be added to the cast film forming part or the peeling part.

  In the step of supplying the polar solvent, when water or an alcohol-based solvent is sprayed onto the casting film, the polar solvent droplet 39 is flowed from the spray nozzle 38 installed immediately before the peeling of the peeling roller 14 in FIG. The polar solvent can be supplied to the interface between the casting film 22 and the endless belt 11 by spraying on the casting film 22. A compressor (not shown) and a solvent supply tank (not shown) are connected to the spray nozzle 38 so that the solvent can be sprayed and sprayed from the nozzle.

  Adjustment of the supply amount of the polar solvent spraying amount, etc. is by monitoring the degree of shrinkage of the above-mentioned casting film, or by measuring the content of the polar solvent in the casting film immediately after peeling, which will be described later, It is preferable to set appropriately.

  Further, the position of the spray nozzle is not limited to that shown in FIG. 3 and may be any time from casting the cast film to peeling it off. Preferably, it is during the period from the latter half of the entire conveying process of the endless belt 11 until peeling, and more preferably, the period from the latter half of the entire conveying process of the endless belt 11 until peeling. It is.

  Moreover, it is preferable to control the temperature of the polar solvent in addition to the injection amount, and it is preferable to appropriately set the temperature by monitoring the degree of shrinkage of the cast film.

  The specification of the spraying apparatus as an example is as follows.

(Blowing device)
Nozzle size: width; set within casting film width + 100 mm Spraying distance: 5-200 mm
Solvent temperature: 0-70 ° C
Spraying time: 0.5 seconds to 3 minutes When the step of supplying the polar solvent immerses the cast film in water or an alcohol solvent, the polar solvent is adjacent to the second heating air supply unit 33 described above. The immersion device 36 is provided with a slit (not shown) so that the casting film 22 can pass through the immersion device. The immersion device 36 has a polar solvent supply pipe 36a on one side and a polar solvent discharge port 36b on the other side, and is controlled by a monitor and a pump (not shown) so that the amount of the polar solvent is constant. However, the liquid circulates in the dipping device 36.

  The casting film 22 and the endless belt 11 are immersed in the polar solvent by the conveying rollers 37a and 37b so that the casting film 22 passes through the immersion device 36 in which the liquid amount is controlled to be constant. A polar solvent can be supplied to the interface. The adjustment of the supply amount is preferably set as appropriate by monitoring the degree of contraction of the above-described casting film or measuring the content of the polar solvent in the casting film immediately after peeling described later.

  It is preferable to control the temperature of the polar solvent in addition to the concentration, and it is preferable to set the temperature appropriately by monitoring the degree of shrinkage of the cast film.

  The specification of the immersion apparatus as an example is as follows.

(Immersion device)
Case size: width: set within casting film width + 100 mm, length: 1-200 mm, height: 5-200 mm
Solution temperature: 0 to 70 ° C
Casting film immersion time: 0.5 seconds to 3 minutes In order to determine whether an appropriate amount of polar solvent was supplied to the casting film in order to express the effect of the present invention by supplying the polar solvent. In addition to monitoring the degree of shrinkage of the cast film, the following method can be employed.

  That is, the cast film immediately after peeling is collected from the support, and the composition of the sample scraped in the depth direction in the range of 10 μm from the surface on the support is analyzed by gas chromatography. This is performed by using the sample with or without the supply of the polar solvent, and an appropriate supply range can be estimated from the comparison with the effect of the present invention (the presence or absence of scaly unevenness). It is preferable to adjust each condition setting of the supply process according to the result.

(First stretching part)
The 1st extending | stretching part 3 performs the 1st extending | stretching process of extending the casting film 22 peeled from the endless belt 11 in MD direction or TD direction, for example, heating the casting film 22 and extending | stretching. Stretching in the MD direction (MD stretching step) while removing the solvent while controlling the temperature conditions. Here, heating air (drying air) is used as the solvent removing means, but there is no particular limitation, and other heating means such as an infrared heater may be used.

  The drying in the 1st extending | stretching part 3 may be dried at fixed temperature, may be divided into the temperature of 3-4 steps, and may be dried at the temperature of several steps.

  About temperature control at the time of performing MD extending | stretching in the 1st extending | stretching part 3, a conventionally well-known system, typically a heater heating system and an oven heating system can be used.

  In the heater heating method, the temperature is instantaneously increased to the stretching temperature by a heater installed between the low-speed roller group that transports the casting film 22 before stretching and the high-speed roller group that transports the casting film 22 after stretching. In this method, stretching is performed with a relatively short stretching span. Since the width shrinkage due to stretching is reduced as the stretching span is shortened, it is preferable that the distance between the low speed roller group and the high speed roller group be as short as possible. In the low-speed roller group, it is preferable to preheat to a temperature as close to the stretching temperature as possible within a range in which film adhesion and scratches do not occur.

  The oven heating method is a method in which an oven is installed between a low-speed roller group and a high-speed roller group, and a preheating zone, a stretching zone, and a cooling zone are provided in the oven, and stretching is performed with a relatively long stretching span.

  The heater heating method is advantageous in that the amount of width shrinkage can be kept small, which is advantageous for forming a wide film, and that it can be installed in a relatively small space. On the other hand, the oven heating method has advantages such as high uniformity of the phase difference, less scratches and adhesive failure. The above-described two heating methods may be appropriately selected in consideration of the material to be used, necessary physical properties, etc. In this embodiment, from the viewpoint of suppressing surface defects of the casting film 22, an oven heating method is used. At this time, the oven is transported in a non-contact manner while floating the film so that the hot air blown from the nozzles arranged above and below the film (casting film) passage does not come into contact with the nozzle. However, floating that extends while stretching is preferred. Hereinafter, the detail of the 1st extending | stretching part 3 which employ | adopted the oven heating system is demonstrated.

  FIG. 8 is a cross-sectional view showing the detailed configuration of the first extending portion 3 along the transport direction. The 1st extending | stretching part 3 has the preheating zone Z1, the extending | stretching zone Z2, and the cooling zone Z3 in order from the conveyance direction upstream of the casting film 22. As shown in FIG. In the preheating zone Z1, the casting film 22 is heated before stretching. In the stretching zone Z2, the casting film 22 conveyed from the preheating zone Z1 may be stretched in the MD direction by a roller (not shown). In the cooling zone Z3, the stretched casting film 22 is cooled. When the temperature is changed in such a zone, the temperature of the preheating zone Z1 is, for example, 200 ° C., the temperature of the stretching zone Z2 is, for example, 180 ° C., and the temperature of the cooling zone Z3 is, for example, 130 ° C. These temperatures may be appropriately set depending on the material of the casting film 22 (material of the optical film to be manufactured) and stretching conditions such as the stretching ratio.

  In the preheating zone Z1 and the stretching zone Z2, nozzles 41 for blowing heated air are arranged in a zigzag pattern in the up and down direction in the transport direction of the casting film 22, and cast between the upper and lower nozzles 41 and 41. The film 22 is conveyed. In addition, in FIG. 8, illustration of the nozzle 41 in the preheating zone Z1 is abbreviate | omitted for convenience. In addition, as shown in FIG. 7, the some nozzle 41 may be opposingly arranged by the up-down direction.

  Above or below the casting film 22, the arrangement pitch p of the nozzles 41 in the transport direction is 100 to 1000 mm, more preferably 250 to 500 mm. Further, the distance d between the upper and lower nozzles 41 and 41 is −50 to 50 mm, more preferably 10 to 30 mm. When the nozzles 41 and 41 are arranged to face each other as shown in FIG. 7, the distance d between the nozzles 41 and 41 is set to be larger than 0 mm. Moreover, the blowing speed (wind speed) at the time of blowing a heating wind from the nozzle 41 is 10-40 m / sec, More preferably, it is 20-30 m / sec.

  In the present embodiment, when the length in the transport direction of the stretching zone Z2 is L (m) and the length in the width direction is W (m), from the viewpoint of obtaining uniform quality in the width direction, L / W Is preferably 1 or more, more preferably 3 or more. If L / W is 3 or more, there is a concern that the stretching zone Z2 becomes longer in the transport direction and the entire apparatus becomes larger in the transport direction. However, a high wind speed (= high heat transfer in the stretching zone Z2). ), The preheating zone Z1 and the cooling zone Z3 can be shortened in the transport direction, and the entire apparatus can be made compact in the transport direction.

  When the heating air is at high wind speed, the end of the casting film 22 may flutter, and the surface of the casting film 22 may be scratched due to contact with the nozzle 41 or may break. However, by adjusting the arrangement pitch p of the nozzles 41 and the distance d between the upper and lower nozzles 41 and 41 according to the elasticity of the casting film 22 in the above range, the fluttering of the casting film 22 is suppressed and surface defects are reduced. High wind speed can be realized while suppressing.

  In the present embodiment, the air curtain C1 is generated between the preheating zone Z1 and the stretching zone Z2, and the casting film 22 is preheated while generating the air curtain C2 between the stretching zone Z2 and the cooling zone Z3. The zone Z1, the stretching zone Z2, and the cooling zone Z3 are passed in this order. Here, the air curtains C1 and C2 are a kind of wall generated by blowing air from a nozzle (not shown), and the air (heating air) in adjacent zones mixes to change the temperature, or the casting film. 22 is generated for the purpose of preventing the accompanying air accompanying the conveyance of 22 from flowing into the downstream zone.

  When the adjacent zones of the first extending portion 3 are partitioned by, for example, partition walls, depending on the partition wall gaps (gap through which the casting film 22 passes), if the casting film 22 flutters during transportation, the casting film 22 is separated from the partition walls. Touching the surface may scratch or damage the surface. However, by generating the air curtains C1 and C2 as described above, there is no fear of surface damage due to fluttering of the casting film 22.

  In addition, it is also possible to avoid damage to the surface due to fluttering of the casting film 22 by forming a large gap through which the casting film 22 passes in the partition wall. However, in this case, when the casting film 22 is transported, the accompanying air easily flows downstream through the gap between the partition walls, so that the air curtains C1 and C2 are generated and the casting film 22 is transported as described above. It is desirable to do.

  In addition, on the upstream side of the inlet of the oven (first extending portion 3) and the downstream side of the outlet, the peripheral surface is a holding angle capable of stably transporting a film (casting film) such as a suction roller or a guide roller. A roller that is wound around, held, and conveyed is disposed. Hereinafter, this point will be described.

  FIG. 8 is a cross-sectional view schematically showing an arrangement example of rollers on the upstream side and the downstream side in the transport direction of the first stretching unit 3. At least one tension regulating roller 51 is provided on the upstream side of the first stretching unit 3 in the transport direction. In the present embodiment, three tension regulating rollers 51 are provided. These tension regulating rollers 51 correspond to the above-described low-speed roller group.

  The tension regulating roller 51 is provided for regulating (relaxing) the tension in the conveying direction applied to the peeling portion of the casting film 22 from the endless belt 11 by MD stretching of the casting film 22 by the first stretching unit 3. Yes. By providing such a tension regulating roller 51, the tension applied to the peeling portion during MD stretching is relaxed, and the casting film 22 is not forcibly pulled in the transport direction at the peeling portion. Thereby, the fluctuation | variation of the peeling position of the casting film 22 can be suppressed, and the casting film 22 can be peeled and conveyed with a predetermined residual solvent amount (described later).

  The holding angle α of the casting film 22 in the tension regulating roller 51 is preferably set to 180 ° or more. In FIG. 8, the holding angle α is approximately 270 °. The holding angle α is the upstream contact on the circumferential surface, the central axis of the roller, and the downstream side on the circumferential surface in a state where the casting film 22 is in contact with the circumferential surface of the tension regulating roller 51. Refers to the angle between contact points. In FIG. 8, auxiliary rollers 52 and 53 are arranged on the upstream side and the downstream side of the tension regulating roller 51, respectively, and pass between the auxiliary roller 52 and the tension regulating roller 51 and between the tension regulating roller 51 and the auxiliary roller 53. Thus, the holding angle (270 °) is realized by allowing the casting film 22 to wrap around the circumferential surface of the tension regulating roller 51.

  Thus, by ensuring the holding angle α of 180 ° or more, the casting film 22 is reliably held on the peripheral surface of the tension regulating roller 51, so that the tension during MD stretching is surely secured by the tension regulating roller 51. It can cut and the fluctuation | variation of the peeling position of the casting film 22 can be suppressed reliably.

  When the number of the tension regulating rollers 51 is large, the apparatus is increased in size, so that 1 to 10 tension regulating rollers 51 are preferably provided, and more preferably 1 to 3 tension regulating rollers 51 are provided.

  On the other hand, at least one transport roller 54 is provided on the downstream side of the first stretching unit 3 in the transport direction, and in the present embodiment, three transport rollers 54 are provided. These transport rollers 54 correspond to the above-described high-speed roller group, and transport the casting film 22 at a speed corresponding to the stretching ratio in the MD direction in the first stretching section 3. For example, if the stretching ratio in the MD direction is twice, the transport roller 54 transports the casting film 22 at twice the speed before stretching.

  The holding angle α of the casting film 22 in the transport roller 54 is set to 180 ° or more, similarly to the tension regulating roller 51 on the upstream side. In FIG. 8, auxiliary rollers 55 and 56 are arranged on the upstream side and the downstream side of the conveyance roller 54, respectively, and are cast between the auxiliary roller 55 and the conveyance roller 54 and between the conveyance roller 54 and the auxiliary roller 56. By holding the film 22 around the circumferential surface of the transport roller 54, the holding angle α is set to 270 °. With such a holding angle α of 180 ° or more, the cast film 22 after MD stretching can be reliably held and transported by the peripheral surface of the transport roller 54.

  When the number of the transport rollers 54 is large, the apparatus is increased in size, so that 1 to 10 transport rollers 54 are preferably provided, and more preferably 1 to 3 transport rollers 54 are provided.

  FIG. 7 is a cross-sectional view schematically illustrating another arrangement example of the rollers on the upstream side and the downstream side in the transport direction of the first stretching unit 3. As shown in the figure, the tension regulating rollers 51 are alternately arranged up and down from the upstream side to the downstream side, and the conveyance rollers 54 are alternately arranged up and down from the upstream side to the downstream side, thereby regulating the tension. The casting film 22 may be transported by setting the holding angle α of the roller 51 and the transport roller 54 to 180 °. Even in this case, the same effect as described above can be obtained.

  FIG. 8 is a cross-sectional view along the width direction showing another configuration example of the roller on the upstream side in the transport direction of the first stretching unit 3. As shown in the figure, one tension regulating roller 51 is disposed on the upstream side in the transport direction of the first stretching unit 3, and both end portions in the width direction of the casting film 22 between the tension regulating roller 51. Auxiliary rollers 57 and 57 for niping may be arranged.

  In this way, the tension in the transport direction of the casting film 22 during MD stretching can also be achieved by niping the end part in the width direction of the casting film 22 with the tension regulating roller 51 and the auxiliary roller 57 (side nip). Therefore, the fluctuation of the peeling position of the casting film 22 can be suppressed. In addition, since the edge part of the casting film 22 is not normally used as a product, a defect such as a scratch may occur on the surface of the edge part of the casting film 22 due to the nip.

  Note that the configuration of the roller shown in FIG. 8 can of course be applied to a roller on the downstream side of the first extending portion 3.

  In the first stretching step, when stretching in the TD direction, it is preferable to use a tenter as disclosed in JP-A-62-46625. The tenter used is not particularly limited and is versatile. From the viewpoint of ease of operation, for example, a clip tenter, a pin tenter and the like can be mentioned, and can be selected and used as necessary. Among these, a tenter method using a clip is preferably used.

(Second stretched part)
The 2nd extending | stretching part 4 shown in FIG. 1 performs the 2nd extending | stretching process of additionally extending the casting film 22 extended | stretched in the 1st extending | stretching part 3 to MD direction or TD direction as needed. It is. For example, the first stretching portion 3 can be stretched in the MD direction, and the second stretching portion 4 can be stretched in the TD direction. Therefore, depending on the extending direction, the first extending portion 3 or the second extending portion 4 can be omitted.

  In this embodiment, the 2nd extending | stretching part 4 is extended | stretched to a TD direction, heating the casting film 22 and removing a solvent. As the solvent removing means, dry air can be used, but there is no particular limitation. In addition, for example, a heating means such as an infrared heater can also be used.

  The drying conditions in the second stretching section 4 vary depending on the amount of residual solvent in the casting film 22 at the start of stretching by the second stretching section 4, but drying time, shrinkage unevenness, stability of the amount of stretching, etc. In addition, it achieves a reasonable stretching, and from the viewpoint of ensuring good dryness, flatness and film thickness uniformity without voids in the manufactured optical film, and ensuring elastic modulus and optical properties. You may dry at the temperature of this, and it may divide into the temperature of 3-4 steps, and may divide into the temperature of several steps, and may dry.

  In any case, it is necessary to perform the temperature conditions for stretching within the range of the characteristics of the present invention.

(Drying part)
For example, the drying unit 5 performs drying of the cast film 22 that has been MD-stretched in the first stretching step and TD-stretched in the second stretching step. The drying unit 5 includes a drying box 5a having a drying air inlet 5b and an outlet 5c, an upper transport roller 5d that transports the casting film 22, and a lower transport roller 5e. The upper transport roller 5d and the lower transport roller 5e are composed of a plurality of sets, one set for the upper and lower sides.

  The number of transport rollers 5d and 5e disposed in the drying unit 5 varies depending on the drying conditions, the drying method, the length of the optical film to be manufactured, and the like, and may be set as appropriate. The upper conveyance roller 5d and the lower conveyance roller 5e are free rotation rollers that are not rotationally driven by a drive source. In addition, a transport roller that freely rotates is not used between the drying unit 5 and the winding unit 6, and usually one to several transport drive rollers (roller that is rotationally driven by a drive source). Requires installation. Basically, the purpose of the driving roller for conveyance is to convey the casting film 22 by its driving, so that the casting film 22 is conveyed and the driving roller is rotated by nip, suction (air suction) or the like. With a mechanism to synchronize with.

  In the drying part 5, you may dry using heating air, infrared rays, etc. independently, and you may dry using heating air and infrared rays together. It is preferable to use heated air from the viewpoint of simplicity. FIG. 1 shows a case where heated air is used. A suitable drying temperature varies depending on the amount of residual solvent in the casting film 22 when entering the drying process, but in consideration of drying time, shrinkage unevenness, stability of the stretch amount, etc., for example, in the range of 30 to 180 ° C. What is necessary is just to select and decide suitably by the amount of residual solvents. Moreover, it may be dried at a constant temperature, or may be divided into three to four stages of temperature and may be divided into several stages of temperature.

  The residual solvent amount of the cast film 22 after the drying process in the drying unit 5 is in the range of 0.01 to 0.5% by mass in consideration of the load of the drying process, the dimensional stability during storage and the expansion / contraction rate. Is preferred. In the present embodiment, the casting film 22 formed by the casting film forming unit 2 is gradually removed of the solvent by the drying unit 5, and the total remaining solvent amount becomes, for example, 2% by mass or less. May be referred to as a film.

(Winding part)
The winding unit 6 is a drying unit 5 that winds an optical film having a predetermined residual solvent amount in a roll shape around a core to a required length. The temperature at the time of winding is preferably cooled to room temperature in order to prevent abrasion, loosening, etc. due to shrinkage after winding. The winder to be used can be used without particular limitation, and may be a commonly used one. For example, a winder that winds by a winding method such as a constant tension method, a constant torque method, a taper tension method, or a program tension controller method with a constant internal stress can be used.

  The casting film 22 is dried and wound up as the optical film F by the drying unit 5 and the winding unit 6 described above.

[1.2] Manufacturing method of optical film The manufacturing method of the optical film of the present invention supplies the polar solvent according to the present invention to the interface between the casting film and the film-forming support, and deposits it by imidization reaction. In addition to producing the same effect as water, the polar solvent acts as a poor solvent on the polyimide resin dope and also causes shrinkage of the cast film, thereby reducing the peel force at the interface and as a transparent optical film application. It solves scaly unevenness, which becomes a problem when used.

  In the present invention, in addition to the above-described method of exposing the cast film in a polar solvent gas atmosphere, the method of spraying the polar solvent, and the method of immersing in the polar solvent, the dope described later is an alcohol solvent as an auxiliary solvent. It is also preferable that the step of supplying the polar solvent contains water in the dope so that the alcohol mass ratio in the total solvent exceeds 3.0%.

(Dope preparation process)
In the method for producing an optical film of the present invention, a soluble and transparent polyimide resin and, if necessary, an additive are dissolved in a solvent to prepare a dope, and the dope is used to form a film by a solution casting film forming method. .

  It is preferable in terms of production cost that the dope is mixed with a crushed recycled material. The return material may be contained in a mass ratio of 10 to 70% by mass with respect to the optical film. If it is 10% by mass or more, it is advantageous in terms of production cost, and if it is 70% by mass or less, it is preferable from the viewpoint of reducing failures (occurrence of foreign matter and gouge) caused by the recycled material.

  Recycled material refers to material generated on the web or film that has not been turned into a product due to accidental accidents during the drying of the optical film or at the final stage, scraping off both ends of the film roll, loss immediately after starting work or adjusting conditions, etc. .

  As the solvent, it is preferable to use a low-boiling solvent having a boiling point of 80 ° C. or lower as the main solvent because the film manufacturing process temperature (particularly the drying temperature) can be reduced, the thermal shrinkage can be reduced, and the film flatness can be improved. . Here, “used as a main solvent” means that if it is a mixed solvent, 55% by mass or more is used with respect to the total amount of the solvent, preferably 70% by mass or more, more preferably 80% by mass or more, and particularly preferably. Is 90% by mass or more. Of course, if it is used alone, it becomes 100% by mass.

  In the case of the present invention, the low boiling point solvent uses dichloromethane as the main solvent, but as other solvents, as non-chlorine solvents, methyl acetate, ethyl acetate, amyl acetate, acetone, methyl ethyl ketone, tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, cyclohexanone, ethyl formate, 2,2,2-trifluoroethanol, 2,2,3,3-hexafluoro-1-propanol, 1,3-difluoro-2-propanol, 1,1, 1,3,3,3-hexafluoro-2-methyl-2-propanol, 1,1,1,3,3,3-hexafluoro-2-propanol, 2,2,3,3,3-pentafluoro -1-propanol, nitroethane, methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec Butanol, tert- butanol and the like.

  Among them, as the low boiling point solvent having a boiling point of 80 ° C. or lower, among the above solvents, preferred solvents to be used with dichloromethane (40 ° C.) are ethyl acetate (77 ° C.), methyl ethyl ketone (79 ° C.), tetrahydrofuran (66 ° C.), It is at least one selected from acetone (56.5 ° C.) and 1,3-dioxolane (75 ° C.) (the parentheses represent boiling points).

  Moreover, as a solvent contained in the case of a mixed solvent, as long as it can dissolve the polyimide resin according to the present invention, it can be used within a range that does not impair the effects of the present invention. For example, N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-diethylacetamide, N, N-dimethylformamide, N, N-diethylformamide, N-methylcaprolactam, hexamethylphosphoramide, tetra Uses methylene sulfone, dimethyl sulfoxide, m-cresol, phenol, p-chlorophenol, 2-chloro-4-hydroxytoluene, diglyme, triglyme, tetraglyme, dioxane, γ-butyrolactone, cyclopentanone, epsilon caprolactam, chloroform, etc. Is possible, It may be used in combination with more species. In addition to these solvents, a poor solvent such as hexane, heptane, benzene, toluene, xylene, chlorobenzene, or o-dichlorobenzene may be used to such an extent that the polyimide resin and additives according to the present invention do not precipitate. .

  Further, when preparing the dope according to the present invention, it is preferable to use an auxiliary solvent, and as the auxiliary solvent, it is preferable to use an alcohol solvent as a polar solvent, and the alcohol solvent is composed of methanol, ethanol and butanol. It is preferable to be selected from the viewpoint of improving peelability, reducing scaly unevenness and enabling high-speed casting. Of these, methanol or ethanol is preferably used. When the ratio of the alcohol in the dope increases, the cast film gels, and the peeling force from the film-forming support can be reduced.

  When the step of supplying the polar solvent uses the aforementioned gas exposure device, spraying device, or immersion device, an alcohol solvent is used as the polar solvent added to the dope, and the total amount of the solvent is. It is preferable to contain in the range of 3.0 mass% or less, and it is more preferable to contain in the range of 1.0-3.0 mass%. If it is 1.0% by mass or more, it is preferable from the viewpoint of further promoting the shrinkage of the cast film and improving the peelability, and if 3.0% by mass or less, from the viewpoint of adjusting the solution haze to 1.0% or less, preferable.

  Moreover, when the process of supplying a polar solvent contains water in a dope, it is preferable to contain 1.0-5.0 mass% of water with respect to the whole amount of solvent of a dope preparation part. 1.0 mass% or more is preferable because it is easy to interact with other alcohol solvents and polyimide resins, and if it is within 5.0 mass%, the solution haze is easily adjusted to 1.0% or less, Moreover, the effect of reducing scaly unevenness is high and preferable. When adding water to the dope, if only water is added to dichloromethane as the main solvent, the solution haze is likely to increase, so it is preferable to use an alcohol solvent as an auxiliary solvent, and the content of the alcohol solvent is The amount is preferably more than 3.0% by mass, and preferably in the range of 3.1 to 4.0% by mass because the solution haze can be reduced.

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

  The prepared dope is guided to a filter by a liquid feed pump or the like and filtered. For example, when the main solvent of the dope is dichloromethane, the gel-like foreign matter in the dope can be removed by filtering the dope at a temperature of boiling point at 1 atm of the dichloromethane + 5 ° C. or more. A preferable temperature range is 45 to 120 ° C, more preferably 45 to 70 ° C, and still more preferably within a range of 45 to 55 ° C.

  Moreover, as a raw material of resin used for dope preparation, what pelletized polyimide resin and other compounds beforehand can be used preferably.

(Casting process)
The prepared dope is fed to a die through a feed pump (for example, a pressurized metering gear pump), and transferred to an endless film-forming support, for example, a metal support such as a stainless steel belt or a rotating metal drum. The dope is cast from the die at the casting position.

  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 width of the cast can be in the range of 1 to 4 m, preferably in the range of 1.5 to 3 m, more preferably in the range of 2 to 2.8 m. The support may not be made of metal, for example, polyethylene terephthalate (PET) film, polyethylene naphthalate (PEN) film, polybutylene terephthalate (PBT) film, nylon 6 film, nylon 6,6 film, polypropylene film. A belt made of polytetrafluoroethylene or the like can be used. For example, when a polyimide resin is used as the flexible substrate, the polyimide resin may be wound together with the metal support on which the polyimide resin is cast.

  The running speed of the metal support is not particularly limited, but is usually 5 m / min or more, preferably 10 to 180 m / min, particularly preferably 80 to 150 m / min. As the traveling speed of the metal support increases, 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 preferable because the higher the temperature, the faster the casting film can be dried. However, if the surface temperature is too high, the casting film may foam or the flatness may deteriorate. It is preferable to set the temperature range appropriately with respect to the boiling point of the solvent.

  In the present invention, the surface temperature of the metal support in the casting step is preferably set in the range of −50 ° C. to the boiling point of the main solvent, more preferably −30 to the boiling point of the main solvent. Higher temperatures are preferred because the drying rate of the cast film can be increased. However, if the temperature is too high, the planarity may deteriorate due to foaming of the web or the like. The preferable support temperature is appropriately determined from 0 ° C. to the boiling point of the main solvent, and more preferably in the range of 5 to 30 ° C.

  The die has a shape that becomes gradually narrower toward the discharge port in a vertical cross section with respect to the width direction. Specifically, the die 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 and titanium. In the present invention, when manufacturing films having different thicknesses, it is not necessary to change to dies having different slit gaps.

  It is preferable to use a pressure die that can adjust the slit shape of the die base portion and can easily make the film thickness uniform. Examples of the pressure die include a coat hanger die and a T die, and any of them is preferably used. Even when films with different thicknesses are continuously manufactured, the discharge rate of the dies is maintained at a substantially constant value. Therefore, when a pressure die is used, conditions such as extrusion pressure and shear rate are also substantially reduced. Maintained at a constant value. In order to increase the film forming speed, two or more pressure dies may be provided on the metal support, and the dope amount may be divided and laminated.

(Solvent evaporation process)
The solvent evaporation step is performed on the metal support, and the cast film is heated on the metal support to evaporate the solvent.

  To evaporate the solvent, for example, a method of blowing heated air from the casting membrane side and the back side of the metal support by a dryer, a method of transferring heat from the back side of the metal support by a heating liquid, a method of transferring heat from the front and back by radiant heat Etc. A method of appropriately selecting and combining them is also preferable. The surface temperature of the metal support may be the same as a whole or may be different depending on the position. The temperature of the heating air is preferably in the range of 10 to 220 ° C.

  The temperature of the heating air (drying temperature) is preferably 200 ° C. or less, more preferably 140 ° C. or less, and further preferably 120 ° C. or less.

  In the solvent evaporation step, it is preferable to dry the cast film until the residual solvent amount falls within the range of 10 to 150% by mass at the time of peeling 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 (web), 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.

(Peeling process)
The cast film from which the solvent has evaporated on the metal support is peeled off at the peeling position.

  The peeling tension at the time of peeling the metal support and the cast film is usually in the range of 60 to 400 N / m. However, if wrinkles easily occur at the time of peeling, the peeling is carried out 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 the solvent evaporates in a short time for casting. From the viewpoint of reducing the peeling force by shrinking the film, it is most preferably in the range of 15 to 40 ° C.

  The peeled film may be sent directly to the stretching step, or may be sent to the stretching step after being sent to the preliminary drying step so as to achieve a desired residual solvent amount. In the present invention, from the viewpoint of adjustment of the residual solvent amount in the stretching step and stable conveyance, the film is preferably sequentially sent to the preliminary drying step and the stretching step after the peeling step.

(Preliminary drying process)
The preliminary drying step (not shown) is a drying step in which the film is heated to further evaporate the solvent. The preliminary drying step may be the zone Z1 of the first drying step. The drying means is not particularly limited, and for example, hot air, infrared rays, a heating roller, microwaves and the like can be used. From the viewpoint of simplicity, it is preferable to dry with hot air or the like while transporting the film with rollers arranged in a staggered manner. The drying temperature is preferably in the range of 30 to 200 ° C. in consideration of the amount of residual solvent and the expansion / contraction rate in conveyance.

  The drying temperature is preferably 200 ° C. or lower, more preferably 140 ° C. or lower, and further preferably 120 ° C. or lower.

(Stretching process)
By stretching the film peeled from the metal support, the film thickness, flatness, orientation and the like of the film can be controlled.

  The stretching temperature in the stretching step is appropriately set. In the present invention, when the glass transition temperature of the polyimide resin is Tg (° C.), the range is (Tg−250 ° C.) to (Tg + 50 ° C.). Preferably it is done.

  The “stretching temperature” refers to the atmospheric temperature in the stretching process. Usually, since the casting film is a thin film, the atmospheric temperature and the temperature of the casting film are almost the same. The measurement can be performed by a thermometer installed in each zone in the stretching process.

  When the stretching temperature is Tg−250 ° C. or higher, the tension at the time of stretching of the optical film does not become too large, the retardation development property with respect to stretching can be easily controlled, and dangers such as breakage can be avoided.

  When the stretching temperature is Tg + 50 ° C. or less, the optical film does not stretch too much and a desired retardation value is easily obtained.

  In addition, the glass transition temperature Tg here is measured at a temperature rising rate of 20 ° C./min using a commercially available differential scanning calorimeter, and is determined at an intermediate glass transition temperature (Tmg) determined according to JIS K7121 (1987). It is. The specific method for measuring the glass transition temperature Tg of the film is measured using a differential scanning calorimeter DSC220 manufactured by Seiko Instruments Inc. according to JIS K7121 (1987).

  Here, the “stretching temperature” refers to a temperature when the temperature during stretching is constant, and refers to an average temperature during stretching when the stretching temperature is changed during the stretching.

  From the viewpoint of obtaining an optical film having good flatness, the change in the stretching temperature from the start of stretching to the end of stretching in the stretching step is preferably within 70 ° C. When changing the temperature, the temperature history may be such that the temperature is gradually increased, the temperature is gradually decreased, or the temperature is increased and then decreased. In any case, the temperature change width should not exceed 70 ° C. Is preferred.

The stretching ratio in the stretching process (first stretching process) by the first stretching section 3 is the definition of the stretching ratio,
Stretch ratio (%) = (dimension after stretching−dimension before stretching) / dimension before stretching × 100
Then, the draw ratio in the MD direction is preferably in the range of 0 (dimension retention) to 100%, and more preferably in the range of 0 (dimension retention) to 30%.

  The draw ratio in the TD direction is preferably in the range of 0 (width retention) to 100%, and more preferably in the range of 5) to 50%.

  The stretching operation may be performed in multiple stages. When biaxial stretching is performed, simultaneous biaxial stretching may be performed or may be performed stepwise. In this case, stepwise means that, for example, stretching in different stretching directions can be sequentially performed, stretching in the same direction is divided into multiple stages, and stretching in different directions is added to any one of the stages. Is also possible.

Thus, for example, the following stretching steps are possible:
-Stretch in MD direction-> Stretch in TD direction-> Stretch in MD direction-> Stretch in MD direction-Stretch in TD direction-> Stretch in TD direction-> Stretch in MD direction-> Stretch in MD direction The case where the film is stretched in the direction and the other is contracted by relaxing the tension is also included.

  It is preferable to control the amount of residual solvent at the time of extending | stretching in the range of 3-100 mass%. Here, “at the time of stretching” means from the start of stretching to the end of stretching.

  If the residual solvent amount is 3% by mass or more, the effect of improving the flatness by stretching can be obtained, and if it is 100% or less, the bowing phenomenon can be suppressed and the in-plane retardation unevenness can be reduced. it can. The residual solvent amount refers to the solvent residual amount from the start of stretching to the end of stretching, and the history thereof is not questioned. For example, it may be 100% by mass at the start of stretching, gradually decrease during stretching, and 3% by mass at the end of stretching.

  From the viewpoint of improving the flatness of the film, it is preferable to stretch the film in the width direction at a stretching speed in the range of 50 to 1000% / min.

  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.

  A 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 stage may be performed at a temperature lower than the stretching temperature in the stretching stage.

(Drying process)
Next, the stretched film is heated and dried. In the case of heating the film with hot air or the like, a means for preventing the mixing of used hot air by installing a nozzle capable of exhausting used hot air (air containing 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, and more preferably 10 seconds to 15 minutes.

  Further, the heating and drying means is not limited to hot air, and for example, infrared rays, heating rollers, microwaves, and the like can be used. From the viewpoint of simplicity, it is preferable to dry with hot air or the like while transporting the film with rollers arranged in a staggered manner. The drying temperature is preferably in the range of 40 to 150 ° C. from the viewpoint of easy heat shrinkage. Furthermore, it is more preferable that it is 40-120 degreeC.

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

(Winding process)
A winding process is a process of winding up the obtained optical film and cooling 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 in particular of an optical film is not restrict | limited, For example, it is preferable to exist in the range of 1-200 micrometers, especially 1-100 micrometers.

  In the winding process, both ends of the optical film sandwiched between tenter clips when stretched and conveyed may be slit. The slit optical film end is preferably cut into a width of 1 to 30 mm and then dissolved in a solvent and reused as a recycled material.

  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.

(Heating process)
After the winding step, a heating step for further heat-treating the optical film dried in the drying step may be performed in order to improve imidization in the polymer chain molecules and between the polymer chain molecules to improve mechanical properties. .

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

  A heating means is performed using well-known means, such as a hot air, an electric heater, and a microwave, for example. As the electric heater, the above-described infrared heater can be used.

  In the heating step, when the optical 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, the process of slitting the end in the width direction of the optical film, or the process of neutralizing the optical film if it is charged, etc. It is good.

<Shape of optical film>
The optical film of the present invention is preferably long, specifically, preferably has a length in the range of about 100 to 10,000 m, and is wound up in a roll shape. The width of the optical film of the present invention is preferably 1 m or more, more preferably 1.4 m or more, and particularly preferably 1.4 to 4 m.

[2] Polyimide resin The polyimide resin according to the present invention is soluble, and the “soluble” is a polyimide resin that is dissolved in 1 g or more in 25 g at 100 ° C. in dichloromethane as described above. Further, the film formed by solution casting using the polyimide resin as a main component is a polyimide which forms a film having a total light transmittance of 80% or more and a yellow index value (YI value) of 6.0 or less, which will be described later. A resin is preferred.

  The polyimide resin according to the present invention is a resin having an imide structure, and is a resin including an imide bond in a repeating unit. The polyimide resin (hereinafter simply referred to as polyimide) is preferably formed from diamine or a derivative thereof and an acid anhydride or a derivative thereof.

[2.1] Polyimide resin having a structure represented by formula (1.1) (1) Structure of acid anhydride The polyimide that can be used in the present invention is particularly represented by the following formula (1.1). A polyimide having a repeating unit (hereinafter referred to as polyimide (A)) is preferred.

In formula (1.1), R represents an aromatic hydrocarbon ring or an aromatic heterocyclic ring, or a tetravalent aliphatic hydrocarbon group or alicyclic hydrocarbon group having 4 to 39 carbon atoms. A represents a group composed of a divalent aliphatic hydrocarbon group having 2 to 39 carbon atoms, an alicyclic hydrocarbon group, an aromatic hydrocarbon group, or a combination thereof, and -O-,- At least one selected from the group consisting of SO ₂ —, —CO—, —CH ₂ —, —C (CH ₃ ) ₂ —, —OSi (CH ₃ ) ₂ —, —C ₂ H ₄ O— and —S—. One group may be contained.

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

  Similarly, examples of the aromatic heterocycle represented by R include a silole ring, a furan ring, a thiophene ring, an oxazole ring, a pyrrole ring, a pyridine ring, a pyridazine ring, a pyrimidine ring, a pyrazine ring, a triazine ring, and an oxadiene ring. Azole ring, triazole ring, imidazole ring, pyrazole ring, thiazole ring, indole ring, benzimidazole ring, benzthiazole ring, benzoxazole ring, quinoxaline ring, quinazoline ring, phthalazine ring, thienothiophene ring, carbazole ring, azacarbazole ring ( Any one of the carbon atoms constituting the dicarbosyl ring, dibenzofuran ring, dibenzothiophene ring, benzothiophene ring or dibenzofuran ring. More than one nitrogen source Ring substituted with Nodioxazine ring, phenanthrazine ring, anthrazine ring, perimidine ring, naphthofuran ring, naphthothiophene ring, naphthodifuran ring, naphthodithiophene ring, anthrafuran ring, anthradifuran ring, anthrathiophene ring, anthradithiophene ring, thianthrene ring Phenoxathiin ring, dibenzocarbazole ring, indolocarbazole ring, dithienobenzene ring and the like.

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

  Examples of the tetravalent alicyclic hydrocarbon group having 4 to 39 carbon atoms represented by R include cyclobutane-1,2,3,4-tetrayl group, cyclopentane-1,2,4,5. -Tetrayl group, cyclohexane-1,2,4,5-tetrayl group, bicyclo [2.2.2] oct-7-ene-2,3,5,6-tetrayl group, bicyclo [2.2.2] Octane-2,3,5,6-tetrayl group, 3,3 ′, 4,4′-dicyclohexyltetrayl group, 3,6-dimethylcyclohexane-1,2,4,5-tetrayl group, 3,6- Examples include diphenylcyclohexane-1,2,4,5-tetrayl group.

  Examples of the divalent aliphatic hydrocarbon group having 2 to 39 carbon atoms which may or may not have the above linking group represented by A include groups represented by the following structural formulas.

  In the above structural formula, n represents the number of repeating units, preferably 1 to 5, and more preferably 1 to 3. X is an alkanediyl group having 1 to 3 carbon atoms, that is, a methylene group, an ethylene group, a trimethylene group, or a propane-1,2-diyl group, and a methylene group is preferable.

  Examples of the divalent alicyclic hydrocarbon group having 2 to 39 carbon atoms which has or does not have the above linking group represented by A include groups represented by the following structural formulas.

  Examples of the divalent aromatic hydrocarbon group having 2 to 39 carbon atoms which has or does not have the above linking group represented by A include groups represented by the following structural formulas.

  Examples of the group consisting of a combination of an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, and an aromatic hydrocarbon group represented by A include groups represented by the following structural formulas.

  The group represented by A is preferably a divalent aromatic hydrocarbon group having 2 to 39 carbon atoms having a bonding group, or a combination of the aromatic hydrocarbon group and an aliphatic hydrocarbon group. A group represented by the following structural formula is preferred.

  The acid anhydride used in the present invention is a carboxylic acid anhydride and is preferably a derivative of an aliphatic or alicyclic tetracarboxylic acid, such as an aliphatic or alicyclic tetracarboxylic acid ester, aliphatic or An alicyclic tetracarboxylic dianhydride etc. are mentioned. Of the aliphatic or alicyclic tetracarboxylic acids or derivatives thereof, alicyclic tetracarboxylic dianhydrides are preferred.

  Here, the derivative is a compound that can be changed to an aliphatic or alicyclic tetracarboxylic acid. For example, in the case of an aliphatic tetracarboxylic dianhydride, a compound having two carboxy groups instead of the anhydride A compound in which one or both of these two carboxy groups is an esterified product, or an acid chloride in which one or both of these two carboxy groups are chlorinated is preferably used.

  By using such an acyl compound, a polyimide film having high heat resistance and excellent optical properties and less coloring (yellowing) can be obtained.

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

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

  Examples of the aliphatic tetracarboxylic dianhydride include 1,2,3,4-butanetetracarboxylic dianhydride. Examples of the alicyclic tetracarboxylic dianhydride include 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,4,5-cyclopentanetetracarboxylic dianhydride, 1,2 , 4,5-cyclohexanetetracarboxylic dianhydride, bicyclo [2.2.2] oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, bicyclo [2.2.2] Examples include octane-2,3,5,6-tetracarboxylic dianhydride. Particularly preferred is 1,2,4,5-cyclohexanetetracarboxylic dianhydride. Generally, a polyimide having an aliphatic diamine as a constituent component forms a strong salt between the polyamic acid, which is an intermediate product, and a diamine. Therefore, in order to increase the molecular weight, a solvent having a relatively high salt solubility (for example, cresol). N, N-dimethylacetamide, γ-butyrolactone, N-methyl-2-pyrrolidone, etc.) are preferably used. However, even with polyimides containing aliphatic diamine as a constituent, when 1,2,4,5-cyclohexanetetracarboxylic dianhydride is used as a constituent, the salt of polyamic acid and diamine is bound by a relatively weak bond. Therefore, high molecular weight is easy and a flexible film is easily obtained.

Other examples include 4,4′-biphthalic anhydride, 4,4 ′-(hexafluoroisopropylidene) diphthalic anhydride, 2,3,3 ′, 4′-biphenyltetracarboxylic dianhydride, 4,4'-oxydiphthalic anhydride, 3,3 ', 4,4'-benzophenone tetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 4- (2, 5-Dioxotetrahydrofuran-3-yl) -1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic anhydride, 5- (2,5-dioxotetrahydrofuryl) -3-methyl-3- Cyclohexene-1,2-dicarboxylic anhydride, 3,3 ', 4,4'-diphenylsulfone tetracarboxylic dianhydride, 3,4'-oxydiphthalic anhydride, 3,4,9,10-perylenetate Dianhydride (Pigment Red 224) 1,2,3,4-tetramethyl-1,2,3,4-cyclobutane tetracarboxylic dianhydride tricyclo [6.4.0.0 ^{2, 7]} dodecane -1,8: 2,7-tetracarboxylic dianhydride and the like can be used.

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

  Aromatic, aliphatic or alicyclic tetracarboxylic acids or derivatives thereof may be used alone or in combination of two or more. Further, other tetracarboxylic acids or derivatives thereof (particularly dianhydrides) may be used in combination as long as the solvent solubility of polyimide, the flexibility of the polyimide film, thermocompression bonding, and transparency are not impaired.

  Examples of such other tetracarboxylic acids or derivatives thereof include pyromellitic acid, 3,3 ′, 4,4′-biphenyltetracarboxylic acid, 2,3,3 ′, 4′-biphenyltetracarboxylic acid, 2, 2-bis (3,4-dicarboxyphenyl) propane, 2,2-bis (2,3-dicarboxyphenyl) propane, 2,2-bis (3,4-dicarboxyphenyl) -1,1,1 , 3,3,3-hexafluoropropane, 2,2-bis (2,3-dicarboxyphenyl) -1,1,1,3,3,3-hexafluoropropane, bis (3,4-dicarboxy) Phenyl) sulfone, bis (3,4-dicarboxyphenyl) ether, bis (2,3-dicarboxyphenyl) ether, 3,3 ′, 4,4′-benzophenonetetracarboxylic acid, 2,2 ′, , 3'-benzophenonetetracarboxylic acid, 4,4- (p-phenylenedioxy) diphthalic acid, 4,4- (m-phenylenedioxy) diphthalic acid, 1,1-bis (2,3-dicarboxyphenyl) ) Aromatic tetracarboxylic acids such as ethane, bis (2,3-dicarboxyphenyl) methane, bis (3,4-dicarboxyphenyl) methane and their derivatives (particularly dianhydrides); ethylenetetracarboxylic acid, etc. And an aliphatic tetracarboxylic acid having 1 to 3 carbon atoms and derivatives thereof (particularly dianhydrides).

  As the acid dianhydride, 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride or biphenyltetracarboxylic dianhydride has excellent transparency and heat due to heat shrinkage. This is preferable from the viewpoint of easy correction.

  The repeating unit represented by the formula (1.1) is preferably 10 to 100 mol%, more preferably 50 to 100 mol%, still more preferably 80 to 100 mol%, particularly preferably based on all repeating units. Is 90 to 100 mol%. The number of repeating units of formula (1.1) in one molecule of polyimide (A) is 10 to 2000, preferably 20 to 200. In this range, the glass transition temperature is 230 to 350 ° C. It is preferable that it is 250-330 degreeC.

(2) Structure of diamine or derivative thereof As the diamine or derivative thereof, for example, aromatic diamine or isocyanate ester is preferable, and aromatic diamine is preferable.

  The diamine or derivative thereof used in the present invention may be an aromatic diamine, an aliphatic diamine, or a mixture thereof, and is preferably an aromatic diamine from the viewpoint of suppressing whitening of the polyimide film.

  In the present invention, the term “aromatic diamine” refers to a diamine in which an amino group is directly bonded to an aromatic ring, and an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, or any other part of its structure. It may contain a substituent (for example, a halogen atom, a sulfonyl group, a carbonyl group, an oxygen atom, etc.). The term “aliphatic diamine” refers to a diamine in which an amino group is directly bonded to an aliphatic hydrocarbon group or an alicyclic hydrocarbon group, and an aromatic hydrocarbon group or other substituent ( For example, it may contain a halogen atom, a sulfonyl group, a carbonyl group, an oxygen atom, etc.).

  Examples of aromatic diamines include, for example, p-phenylenediamine, m-phenylenediamine, 2,4-diaminotoluene, 2,6-diaminotoluene, benzidine, o-tolidine, m-tolidine, bis (trifluoromethyl). Benzidine, octafluorobenzidine, 3,3'-dihydroxy-4,4'-diaminobiphenyl, 3,3'-dimethoxy-4,4'-diaminobiphenyl, 3,3'-dichloro-4,4'-diaminobiphenyl 3,3'-difluoro-4,4'-diaminobiphenyl, 2,6-diaminonaphthalene, 1,5-diaminonaphthalene, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4 ' -Diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, 3,4'-di Minodiphenylsulfone, 4,4'-diaminobenzophenone, 2,2-bis (4- (4-aminophenoxy) phenyl) propane, 2,2-bis (4- (2-methyl-4-aminophenoxy) phenyl) Propane, 2,2-bis (4- (2,6-dimethyl-4-aminophenoxy) phenyl) propane, 2,2-bis (4- (4-aminophenoxy) phenyl) hexafluoropropane, 2,2- Bis (4- (2-methyl-4-aminophenoxy) phenyl) hexafluoropropane, 2,2-bis (4- (2,6-dimethyl-4-aminophenoxy) phenyl) hexafluoropropane, 4,4 ′ -Bis (4-aminophenoxy) biphenyl, 4,4'-bis (2-methyl-4-aminophenoxy) biphenyl, 4,4'-bis (2, -Dimethyl-4-aminophenoxy) biphenyl, 4,4'-bis (3-aminophenoxy) biphenyl, bis (4- (4-aminophenoxy) phenyl) sulfone, bis (4- (2-methyl-4-amino) Phenoxy) phenyl) sulfone, bis (4- (2,6-dimethyl-4-aminophenoxy) phenyl) sulfone, bis (4- (4-aminophenoxy) phenyl) ether, bis (4- (2-methyl-4) -Aminophenoxy) phenyl) ether, bis (4- (2,6-dimethyl-4-aminophenoxy) phenyl) ether, 1,4-bis (4-aminophenoxy) benzene, 1,4-bis (2-methyl) -4-aminophenoxy) benzene, 1,4-bis (2,6-dimethyl-4-aminophenoxy) benzene, 1,3-bis (4- Aminophenoxy) benzene, 1,3-bis (2-methyl-4-aminophenoxy) benzene, 1,3-bis (2,6-dimethyl-4-aminophenoxy) benzene, 2,2-bis (4-amino) Phenyl) propane, 2,2-bis (2-methyl-4-aminophenyl) propane, 2,2-bis (3-methyl-4-aminophenyl) propane, 2,2-bis (3-ethyl-4-) Aminophenyl) propane, 2,2-bis (3,5-dimethyl-4-aminophenyl) propane, 2,2-bis (2,6-dimethyl-4-aminophenyl) propane, 2,2-bis (4 -Aminophenyl) hexafluoropropane, 2,2-bis (2-methyl-4-aminophenyl) hexafluoropropane, 2,2-bis (2,6-dimethyl-4-aminophenyl) Xafluoropropane, α, α′-bis (4-aminophenyl) -1,4-diisopropylbenzene, α, α′-bis (2-methyl-4-aminophenyl) -1,4-diisopropylbenzene, α, α'-bis (2,6-dimethyl-4-aminophenyl) -1,4-diisopropylbenzene, α, α'-bis (3-aminophenyl) -1,4-diisopropylbenzene, α, α'-bis (4-aminophenyl) -1,3-diisopropylbenzene, α, α'-bis (2-methyl-4-aminophenyl) -1,3-diisopropylbenzene, α, α'-bis (2,6-dimethyl) -4-aminophenyl) -1,3-diisopropylbenzene, α, α'-bis (3-aminophenyl) -1,3-diisopropylbenzene, 1,1-bis (4-aminophenyl) Cyclopentane, 1,1-bis (2-methyl-4-aminophenyl) cyclopentane, 1,1-bis (2,6-dimethyl-4-aminophenyl) cyclopentane, 1,1-bis (4-amino) Phenyl) cyclohexane, 1,1-bis (2-methyl-4-aminophenyl) cyclohexane, 1,1-bis (2,6-dimethyl-4-aminophenyl) cyclohexane, 1,1-bis (4-aminophenyl) ) 4-methyl-cyclohexane, 1,1-bis (4-aminophenyl) norbornane, 1,1-bis (2-methyl-4-aminophenyl) norbornane, 1,1-bis (2,6-dimethyl-4) -Aminophenyl) norbornane, 1,1-bis (4-aminophenyl) adamantane, 1,1-bis (2-methyl-4-aminophenyl) adamanta 1,1-bis (2,6-dimethyl-4-aminophenyl) adamantane, 1,4-phenylenediamine, 3,3′-diaminobenzophenone, 2,2-bis (3-aminophenyl) hexafluoropropane, 3-aminobenzylamine, 2,2-bis (3-amino-4-methylphenyl) hexafluoropropane, 1,3-bis (3-aminophenoxy) benzene, 2,2-bis [4- (4-amino Phenoxy) phenyl] propane, bis [4- (3-aminophenoxy) phenyl] sulfone, 1,3-bis [2- (4-aminophenyl) -2-propyl] benzene, bis (2-aminophenyl) sulfide, Bis (4-aminophenyl) sulfide, 1,3-bis (3-aminopropyl) tetramethyldisiloxane, 4,4'-diamidine -3,3'-dimethyldiphenylmethane, 3,3'-diaminodiphenylmethane, 4,4'-ethylenedianiline, 4,4'-methylenebis (cyclohexylamine), 4,4'-methylenebis (2,6-diethylaniline) ), 4,4'-methylenebis (2-methylcyclohexylamine), and the like.

  Examples of the aliphatic diamine include ethylene diamine, hexamethylene diamine, polyethylene glycol bis (3-aminopropyl) ether, polypropylene glycol bis (3-aminopropyl) ether, 1,3-bis (aminomethyl) cyclohexane, 1,4. -Bis (aminomethyl) cyclohexane, m-xylylenediamine, p-xylylenediamine, 1,4-bis (2-amino-isopropyl) benzene, 1,3-bis (2-amino-isopropyl) benzene, isophorone Diamine, norbornane diamine, siloxane diamine, 4,4'-diaminodicyclohexylmethane, 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane, 3,3'-diethyl-4,4'-diaminodicyclohexylmethane, 3, , 3 ' 5,5'-tetramethyl-4,4'-diaminodicyclohexylmethane, 2,3-bis (aminomethyl) -bicyclo [2.2.1] heptane, 2,5-bis (aminomethyl) -bicyclo [2 2.1] heptane, 2,6-bis (aminomethyl) -bicyclo [2.2.1] heptane, 2,2-bis (4,4'-diaminocyclohexyl) propane, 2,2-bis (4 , 4'-diaminomethylcyclohexyl) propane and the like.

  Moreover, you may use the diamine which has a fluorene skeleton, or its derivative (s) for the purpose of improving coloring peculiar to a polyimide. For example, 9,9-bis [4- (4-aminophenoxy) phenyl] fluorene, 9,9-bis [4- (4-aminophenoxy) -3-phenylphenyl] fluorene, 9,9-bis [4- (3-aminophenoxy) -3-phenylphenyl] fluorene, 9,9-bis [4- (2-aminophenoxy) -3-phenylphenyl] fluorene, 9,9-bis [4- (4-amino-3) -Methylphenoxy) -3-phenylphenyl] fluorene, 9,9-bis [4- (4-amino-2-methylphenoxy) -3-phenylphenyl] fluorene, 9,9-bis [4- (4-amino) -3-ethylphenoxy) -3-phenylphenyl] fluorene and the like can be used.

  A diamine compound having a triazine mother nucleus represented by the following formula can be preferably used.

In the diamine compound of the above formula having a triazine mother nucleus, R ¹ represents a hydrogen atom or an alkyl group or aryl group having 1 to 12 carbon atoms (preferably 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms), R ² represents an alkyl group or an aryl group having 1 to 12 carbon atoms (preferably 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms), and R ¹ and R ² may be different or the same. May be.

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

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

  Specific examples of the diamine compound represented by the above formula having a triazine mother nucleus include 2,4-bis (4-aminoanilino) -6-anilino-1,3,5-triazine, 2,4-bis ( 3-aminoanilino) -6-anilino-1,3,5-triazine, 2,4-bis (4-aminoanilino) -6-benzylamino-1,3,5-triazine, 2,4-bis (3-aminoanilino) ) -6-Benzylamino-1,3,5-triazine, 2,4-bis (4-aminoanilino) -6-naphthylamino-1,3,5-triazine, 2,4-bis (4-aminoanilino)- 6-biphenylamino-1,3,5-triazine, 2,4-bis (4-aminoanilino) -6-diphenylamino-1,3,5-triazine, 2,4-bis (3-aminoanilino) -6 Phenylamino-1,3,5-triazine, 2,4-bis (4-aminoanilino) -6-dibenzylamino-1,3,5-triazine, 2,4-bis (4-aminoanilino) -6-di Naphtylamino-1,3,5-triazine, 2,4-bis (4-aminoanilino) -6-N-methylanilino-1,3,5-triazine, 2,4-bis (4-aminoanilino) -6-N -Methylnaphthylamino-1,3,5-triazine, 2,4-bis (4-aminoanilino) -6-methylamino-1,3,5-triazine, 2,4-bis (3-aminoanilino) -6 Methylamino-1,3,5-triazine, 2,4-bis (4-aminoanilino) -6-ethylamino-1,3,5-triazine, 2,4-bis (3-aminoanilino) -6-ethylamino 1,3,5-triazine, 2,4-bis (4-aminoanilino) -6-dimethylamino-1,3,5-triazine, 2,4-bis (3-aminoanilino) -6-dimethylamino-1, 3,5-triazine, 2,4-bis (4-aminoanilino) -6-diethylamino-1,3,5-triazine, 2,4-bis (4-aminoanilino) -6-dibutylamino-1,3,5 -Triazine, 2,4-bis (4-aminoanilino) -6-amino-1,3,5-triazine, 2,4-bis (3-aminoanilino) -6-amino-1,3,5-triazine, etc. Can be mentioned.

  Examples of the isocyanate ester which is a diamine derivative include diisocyanates obtained by reacting the above aromatic or aliphatic diamines with phosgene.

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

  As the diamine, 2,2′-bis (trifluoromethyl) -4,4′-diaminobiphenyl is preferable from the viewpoint of excellent transparency and easy thermal correction by heat shrinkage.

  The above diamines and derivatives thereof may be arbitrarily mixed and used, but the amount of diamine in them is preferably 50 to 100 mol%, more preferably 80 to 100 mol%.

[2.2] Synthesis method and imidization of polyamic acid (1) Synthesis of polyamic acid In a suitable solvent, polyamic acid is a polymerization reaction of at least one of the tetracarboxylic acids and at least one of the diamines. Is obtained.

  The polyamic acid ester is diesterified by ring-opening the tetracarboxylic dianhydride with an alcohol such as methanol, ethanol, isopropanol, or n-propanol, and the obtained diester is converted into the above-mentioned diester in an appropriate solvent. It can be obtained by reacting with a diamine compound. Furthermore, the polyamic acid ester can also be obtained by esterification by reacting the carboxylic acid group of the polyamic acid obtained as described above with an alcohol as described above.

  The reaction between the tetracarboxylic dianhydride and the diamine compound can be carried out under conventionally known conditions. There are no particular limitations on the order of addition or addition method of the tetracarboxylic dianhydride and the diamine compound. For example, a polycarboxylic acid can be obtained by sequentially adding a tetracarboxylic dianhydride and a diamine compound to a solvent and stirring at an appropriate temperature.

  The amount of the diamine compound is usually 0.8 mol or more, preferably 1 mol or more with respect to 1 mol of tetracarboxylic dianhydride. On the other hand, it is 1.2 mol or less normally, Preferably it is 1.1 mol or less. The yield of the polyamic acid obtained can be improved by making the quantity of a diamine compound into such a range.

  The concentration of the tetracarboxylic dianhydride and the diamine compound in the solvent is appropriately set according to the reaction conditions and the viscosity of the polyamic acid solution. For example, the total mass of the tetracarboxylic dianhydride and the diamine compound is not particularly limited, but is usually 1% by mass or more, preferably 5% by mass or more with respect to the total amount of the solution, while usually 70%. It is not more than mass%, preferably not more than 30 mass%. By setting the amount of the reaction substrate in such a range, the polyamic acid can be obtained at a low cost and in a high yield.

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

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

  As the terminal group of the polyamic acid, an acid anhydride group or an amino group can be arbitrarily selected by using either one of a tetracarboxylic dianhydride or a diamine compound in excess during the polymerization reaction.

  When the terminal group is an acid anhydride terminal, the acid anhydride terminal may be left without performing the subsequent treatment, or may be hydrolyzed to form a dicarboxylic acid. Moreover, it is good also as ester using C4 or less alcohol. Furthermore, you may seal a terminal | end using a monofunctional amine compound or an isocyanate compound. The amine compound or isocyanate compound used here is not particularly limited as long as it is a monofunctional primary amine compound or isocyanate compound. For example, aniline, methylaniline, dimethylaniline, trimethylaniline, ethylaniline, diethylaniline, triethylaniline, aminophenol, methoxyaniline, aminobenzoic acid, biphenylamine, naphthylamine, cyclohexylamine, phenyl isocyanate, xylylene isocyanate, cyclohexyl isocyanate , Methylphenyl isocyanate, trifluoromethylphenyl isocyanate, and the like.

Further, when the terminal group is an amine terminal, it is possible to prevent the amino group from remaining at the terminal by sealing the terminal amino group with a monofunctional acid anhydride. As an acid anhydride used here, if it is a monofunctional acid anhydride which becomes dicarboxylic acid or tricarboxylic acid when hydrolyzed, it can be used without particular limitation. For example, maleic anhydride, methyl maleic anhydride, dimethyl maleic anhydride, succinic anhydride, norbornene dicarboxylic anhydride, 4- (phenylethynyl) phthalic anhydride, 4-ethynyl phthalic anhydride, phthalate Acid anhydride, methylphthalic anhydride, dimethylphthalic anhydride, trimellitic anhydride, naphthalenedicarboxylic anhydride, 7-oxabicyclo [2.2.1] heptane-2,3-dicarboxylic anhydride, bicyclo [2.2.1] Heptane-2,3-dicarboxylic anhydride, bicyclo [2.2.2] oct-5-ene-2,3-dicarboxylic anhydride, 4-oxatricyclo [5.2 .2.0 ^2,6] undecane-3,5-dione, octahydro-1,3-dioxo-isobenzofuran-5-carboxylic acid, hexahydrophthalic anhydride , Methylhexahydrophthalic anhydride, dimethylcyclohexanedicarboxylic anhydride, 1,2,3,6-tetrahydrophthalic anhydride, methyl-4-cyclohexene-1,2-dicarboxylic anhydride, and the like. .

(2) Imidization method Here, the polyimide is prepared by heating a polyamic acid solution to imidize the polyamic acid (thermal imidization method), or adding a ring-closing catalyst (imidation catalyst) to the polyamic acid solution. It can be obtained by a method of imidizing polyamic acid (chemical imidization method).

  Also, a method of imidizing polyamic acid by heating the polyamic acid solution (thermal imidization method), or a method of imidizing polyamic acid by adding a ring-closing catalyst (imidation catalyst) to the polyamic acid solution (chemical imide) As for the conversion method), a reaction vessel for polymerizing polyamic acid from an acid anhydride and a diamine may be continued as it is and imidized in the reaction vessel.

  In the thermal imidization method in the reaction kettle, the polyamic acid in the polymerization solvent is heat-treated in a temperature range of, for example, 80 to 300 ° C. for 0.1 to 200 hours to advance imidization. Moreover, it is preferable that the said temperature range shall be 150-200 degreeC, By making it 150 degreeC or more, imidation can be made to advance reliably and can be completed, On the other hand, by making it 200 degrees C or less, a solvent and It is possible to prevent the resin concentration from increasing due to oxidation of unreacted raw materials and volatilization of the solvent.

  Further, in the thermal imidization method, an azeotropic solvent can be added to the polymerization solvent in order to efficiently remove water generated by the imidization reaction. As the azeotropic solvent, for example, aromatic hydrocarbons such as toluene, xylene and solvent naphtha, and alicyclic hydrocarbons such as cyclohexane, methylcyclohexane and dimethylcyclohexane can be used. When using an azeotropic solvent, the addition amount is about 1 to 30% by mass, preferably 5 to 20% by mass, based on the total amount of organic solvent.

  On the other hand, in the chemical imidization method, a known ring closure catalyst is added to the polyamic acid in the polymerization solvent to advance imidization. Specific examples of the ring-closing catalyst include aliphatic tertiary amines such as trimethylamine and triethylenediamine, and heterocyclic tertiary amines such as isoquinoline, pyridine and picoline. Examples thereof include substituted nitrogen-containing heterocyclic compounds, N-oxide compounds of nitrogen-containing heterocyclic compounds, substituted or unsubstituted amino acid compounds, aromatic hydrocarbon compounds having an hydroxy group, or aromatic heterocyclic compounds. -Lower alkyl imidazole such as dimethylimidazole, N-methylimidazole, N-benzyl-2-methylimidazole, 2-methylimidazole, 2-ethyl-4-methylimidazole, 5-methylbenzimidazole, N-benzyl-2-methyl Imidazole derivatives such as imidazole, isoquinoline, 3 It is preferable to use a substituted pyridine such as 5-dimethylpyridine, 3,4-dimethylpyridine, 2,5-dimethylpyridine, 2,4-dimethylpyridine, 4-n-propylpyridine, p-toluenesulfonic acid, etc. it can. The addition amount of the ring closure catalyst is preferably about 0.01 to 2 times equivalent, particularly about 0.02 to 1 time equivalent to the amic acid unit of the polyamic acid. By using a ring-closing catalyst, the properties of the resulting polyimide, particularly elongation and breaking resistance, may be improved.

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

  Thus, the polyimide solution imidized in the reaction kettle is advantageous because it is less likely to cause a decrease in molecular weight due to hydrolysis over time than the polyimide solution.

  Further, since the imidization reaction has progressed in advance, for example, in the case of a polyimide having an imidization rate of 100%, imidization on the cast film is unnecessary, and the drying temperature can be lowered.

  Alternatively, the ring-closed polyimide may be reprecipitated and purified using a poor solvent or the like to obtain a solid, and then dissolved in a solvent and cast and dried to form a film.

  According to this method, the polymerization solvent and the solvent to be cast can be made different types, and the performance of the polyimide film can be further extracted by selecting an optimum solvent for each.

  For example, in order to increase the molecular weight of polyamic acid, it is polymerized and cyclized with dimethylacetamide, solidified with methanol, dried, then made into a solution containing an additive with dichloromethane, then cast and dried. Thus, high molecular weight and low temperature drying are possible.

  Moreover, when using dichloromethane as a solvent, it can be used in combination with other solvents. A co-solvent such as tetrahydrofuran (THF), 1,3-dioxolane, cyclohexanone, cyclopentanone, γ-butyrolactone, ethanol, methanol, butanol, or isopropyl alcohol can be used as appropriate.

(3) Other polyimides In addition to the polyimides described above, polyimides containing atoms such as phosphorus, silicon, and sulfur can also be used.

  For example, as polyimide containing phosphorus, use polyimides described in paragraphs [0010]-[0021] of JP2011-74209A and paragraphs [0011]-[0025] of JP2011-074177A, respectively. Can do.

  As a polyimide containing silicon, a polyimide obtained by imidizing a polyimide precursor described in paragraphs [0030]-[0045] of JP2013-028796A can be used.

  Examples of the polyimide containing sulfur include paragraphs [0009]-[0025] of JP 2010-189322 A, paragraphs [0012]-[0025] of JP 2008-274234 A, and paragraphs of JP 2008-274229 A. Polyimides obtained by imidizing a polyimide precursor described in each of [0012]-[0023] can be used.

  In addition, the alicyclic polyimide described in paragraphs [0008]-[0012] of JP-A-2009-256590 and paragraphs [0008]-[0012] of JP-A-2009-256589 are preferably used. it can.

[2.3] Polyamideimide The polyamideimide used is a polyamideimide containing tricarboxylic acid or tetracarboxylic acid, dicarboxylic acid as an acid component, and diamine as a structural unit as an amine component.

The polyamideimide used 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, monoanhydrides such as tricarboxylic acid such as butane-1,2,4-tricarboxylic acid, esterified compounds, or a mixture of two or more.

  b) Tetracarboxylic acid; 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'-benzophenonetetracarboxylic 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.

(1) Polyamideimide having a structure represented by the formula (2) as an essential component One preferred embodiment has a structure represented by the formula (2) as an essential component, and further includes formulas (3) and (4). ) And at least one structure selected from the group represented by formula (5) is a polyamide-imide resin containing in the molecular chain as a repeating unit.

（Ｘは、酸素原子、ＣＯ、ＳＯ_２、又は、結合を表す。ｎは０又は１を表す。）

(X represents an oxygen atom, CO, SO ₂ , or a bond. 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 (3), X is preferably SO ₂ or a bond (biphenyl bond), or n = 0. More preferably, X is a bond (biphenyl bond) or n = 0. In formula (4), Y is preferably a benzophenone type (CO) or a bond type (biphenyl bond).

  In formula (4), Y is preferably a benzophenone type (CO) or a bond type (biphenyl bond).

  One preferred embodiment is that formula (2) is a repeating unit from trimellitic anhydride and 1,5-naphthalene diisocyanate, formula (3) is a repeating unit from terephthalic acid and 1,5-naphthalene diisocyanate, formula (4) Is a repeating unit from biphenyltetracarboxylic dianhydride or benzophenonetetracarboxylic dianhydride and 1,5-naphthalene diisocyanate, the content ratio of which is represented by formula (2) / {formula (3) + formula (4) + Formula (5)} = 1/99 to 40/60 molar ratio, and Formula (3) / Formula (4) = 10/90 to 90/10 molar ratio is preferable.

  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, an isocyanate method, an 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, as described above. For reasons such as ensuring the reliability of peel 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.

(2) Polyamideimide having a structure represented by formula (6) or formula (7) As a preferred polyamideimide resin, a compound containing the following formula (6) as a structural unit can be preferably used. Hereinafter, the compound having a structure represented by the formula (6) will be described.

(In the formula, R ₁ is an aryl group or a cycloalkane group, and may contain nitrogen, oxygen, sulfur, or halogen.)
(Diamine component of polyamideimide resin)
Examples of the diamine component include p-phenylenediamine, m-phenylenediamine, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfone, and 3,3'-diaminodiphenyl sulfone. 3,4'-diaminobiphenyl, 3,3'-diaminobiphenyl, 3,3'-diaminobenzanilide, 4,4'-diaminobenzanilide, 4,4'-diaminobenzophenone, 3,3'-diaminobenzophenone 3,4'-diaminobenzophenone, 2,6-tolylenediamine, 2,4-tolylenediamine, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl Propane, 3,3'-diaminodiphenylpropane, , 3'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, P-xylenediamine, m-xylenediamine, 1,4-naphthalenediamine, 1,5-naphthalenediamine, 2,6-naphthalenediamine, 2,7- Naphthalenediamine, 2,2'-bis (4-aminophenyl) propane, 1,3-bis (3-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,4-bis (4 -Aminophenoxy) benzene, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, bis [4- (4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] Sulfone, bis [4- (3-aminophenoxy) phenyl] propane, 4,4′-bis (4-aminophene) Xyl) biphenyl, 4,4'-bis (3-aminophenoxy) biphenyl, 3,3'-dimethyl-4,4'-diaminobiphenyl, 4-methyl-1,3-phenylenediamine, 3,3'-diethyl -4,4'-diaminobiphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, 2,2'-diethyl-4,4'-diaminobiphenyl, 3,3'-dimethoxy-4,4 ' -Diaminobiphenyl, 3,3'-diethoxy-4,4'-diaminobiphenyl, trans-1,4-diaminocyclohexane, cis-1,4-diaminocyclohexane, 1,4-diaminocyclohexane (trans / cis mixture), 1,3-diaminocyclohexane, dicyclohexylmethane-4,4'-diamine (trans isomer, cis isomer, trans / cis mixture) , Isophoronediamine, 1,4-cyclohexanebis (methylamine), 2,5-bis (aminomethyl) bicyclo [2.2.1] heptane, 2,6-bis (aminomethyl) bicyclo [2.2.1] ] Heptane, 3,8-bis (aminomethyl) tricyclo [5.2.1.0] decane, 1,3-diaminoadamantane, 4,4'-methylenebis (2-methylcyclohexylamine), 4,4'- Methylenebis (2-ethylcyclohexylamine), 4,4'-methylenebis (2,6-dimethylcyclohexylamine), 4,4'-methylenebis (2,6-diethylcyclohexylamine), 2,2-bis (4-amino) Cyclohexyl) propane, 2,2-bis (4-aminocyclohexyl) hexafluoropropane, 1,3-propanediamine, 4-tetramethylenediamine, 1,5-pentamethylenediamine, 1,6-hexamethylenediamine, 1,7-heptamethylenediamine, 1,8-octamethylenediamine, 1,9-nonamethylenediamine alone, or A mixture of two or more, or a diisocyanate corresponding to these, or a mixture of two or more can be used as the diamine component.

  Preferably, 3,3′-dimethyl-4,4′-diaminobiphenyl, dicyclohexylmethane-4,4′-diamine (trans isomer, cis isomer, trans / cis mixture), 4,4′-diaminodiphenyl ether, p- Using phenylenediamine, 4-methyl-1,3-phenylenediamine, or the like alone, or a mixture of two or more, or a diisocyanate corresponding to these alone, or a mixture of two or more, as the diamine component. it can.

  More preferably, 3,3′-dimethyl-4,4′-diaminobiphenyl, dicyclohexylmethane-4,4′-diamine (trans isomer, cis isomer, trans / cis mixture), 4,4′-diaminodiphenyl ether, 4 -Methyl-1,3-phenylenediamine or the like alone, or a mixture of two or more kinds, or a diisocyanate corresponding to these alone or a mixture of two or more kinds can be used as the diamine component.

  More preferably, 3,3′-dimethyl-4,4′-diaminobiphenyl, dicyclohexylmethane-4,4′-diamine (trans isomer, cis isomer, trans / cis mixture), 4-methyl-1,3-phenylene A diamine or the like alone, or a mixture of two or more kinds, or a diisocyanate corresponding to these alone or a mixture of two or more kinds can be used as the diamine component.

(Preferable combination of acid component and diamine component)
Among the above acid components and diamine components, the following components are obtained from the heat resistance, solvent resistance, and durability in the process of forming a film, and the heat resistance, surface smoothness, and transparency of the produced polyamideimide film. Is preferably used.

  As the acid component, cyclohexane-1,2,4-tricarboxylic acid-1,2-anhydride can be used. Polyamideimide resin containing cyclohexane-1,2,4-tricarboxylic acid-1,2-anhydride as an acid component can be used.

  As the diamine component, at least one or two compounds selected from the group consisting of 3,3′-dimethyl-4,4′-diaminobiphenyl and 4-methyl-1,3-phenylenediamine, or 3,3 At least one or two compounds selected from the group consisting of '-dimethyl-4,4'-diisocyanate biphenyl (o-tolidine diisocyanate) and 4-methyl-1,3-phenylene diisocyanate (tolylene diisocyanate); Can be used.

  Moreover, as a preferable polyamideimide resin, a compound containing a structure represented by the following formula (7) as a structural unit can be used.

(Wherein R ₂ and R ₃ each represent hydrogen, an alkyl group having 1 to 3 carbon atoms or an aryl group, and may contain nitrogen, oxygen, sulfur or halogen.)
When the total acid component is 100 mol%, the exemplified acid component is preferably contained in an amount of 50 mol% to 100%, more preferably 70 mol% to 100%. Further, when the total diamine component is 100 mol%, the exemplified diamine component may be contained in an amount of 50 mol% to 100%, more preferably 70 mol% to 100%. Within these ranges, the heat resistance and durability in the process of forming a film are good, and the heat resistance, surface smoothness, and transparency of the resulting polyamideimide film are particularly improved.

The molecular weight of the polyamide-imide resin used is a molecular weight corresponding to 0.3 to 2.5 cm ³ / g in N-methyl-2-pyrrolidone (polymer concentration 0.5 g / cm ³ ) with a logarithmic viscosity at 30 ° C. And more preferably those having a molecular weight corresponding to 0.5 to 2.0 cm ³ / g. When the logarithmic viscosity is 0.3 cm ³ / g or more, mechanical properties are sufficient when formed into a molded product such as a film. On the other hand, if it is 2.0 cm ³ / g or less, the solution viscosity does not become too high and the molding process becomes easy.

[2.4] Polyetherimide The polyetherimide used is a thermoplastic resin containing an aromatic nucleus bond and an imide bond in its structural unit, and is not particularly limited. Specifically, the following formula (8 Or a polyetherimide having a repeating unit having a structure represented by the following formula (9).

  Polyetherimides having a repeating unit having the structure represented by the above formula (8) are trade names “Ultem 1000” (glass transition temperature: 216 ° C.) and “Ultem 1010” (glass transition temperature: 216) manufactured by General Electric Co., Ltd. ° C), polyetherimide having a repeating unit having the structure represented by the above formula (9) includes “Ultem CRS5001” (glass transition temperature Tg 226 ° C.), and other specific examples are manufactured by Mitsui Chemicals, Inc. Trade name “Aurum PL500AM” (glass transition temperature 258 ° C.).

  Although the manufacturing method of the said polyetherimide is not specifically limited, Usually, the amorphous polyetherimide which has a structure represented by the said Formula (8) is 4,4 '-[isopropylidenebis (p -Phenyleneoxy)] diphthalic acid dianhydride and m-phenylenediamine as a polycondensate, and polyetherimide having the structure represented by the above structural formula (9) is 4,4 '-[isopropylidenebis (P-phenyleneoxy)] diphthalic acid dianhydride and p-phenylenediamine are synthesized by a known method.

  Further, the polyetherimide may contain other copolymerizable monomer units such as an amide group, an ester group, and a sulfonyl group within the range not exceeding the gist of the present invention. In addition, polyetherimide can be used individually by 1 type or in combination of 2 or more types.

[2.5] Polyesterimide The transparent heat-resistant resin having an imide structure preferably contains a polyesterimide structure represented by the formula (10) in the structural unit.

(In formula (10), R ₁ represents a divalent group having a specific structure. R ₂ represents a divalent chain aliphatic group, a divalent cycloaliphatic group or a divalent aromatic group. Represents.)
In Formula (10), R ₁ represents a divalent group having a structure represented by Formula (11), Formula (12), or Formula (13), respectively.

(Divalent group having a structure represented by the formula (11))

  In formula (11), R represents a divalent chain aliphatic group, cycloaliphatic group or aromatic group, and a plurality of R may be the same 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 such as an “aromatic compound having a valent hydroxy group” is desirable. Further, it may be a residue derived from “polycarbonate diol” which can be polymerized from the diol and carbonates or phosgene.

  As the “chain aliphatic compound having a divalent hydroxy group”, a branched or linear diol having two hydroxy groups can be used. For example, alkylene diol, polyoxyalkylene diol, polyester diol, polycaprolactone diol and the like can be mentioned. Examples of branched or linear diols having two hydroxy groups that can be used as the “chain aliphatic compound having a divalent hydroxy group” are listed below.

  Examples of the alkylene diol include ethylene glycol, diethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 2-methyl-1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,4-cyclohexanediol, 1,4- And cyclohexanedimethanol.

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

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

  As the “polyhydric alcohol component” used in the polyester diol, any of various polyhydric alcohols can be used. For example, ethylene glycol, propylene glycol, 1,3-propanediol, 2-methyl-1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5 -Pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, diethylene glycol, dipropylene glycol, 2,2,4-trimethyl-1,3-pentanediol, cyclohexanemethanol, Neopentyl hydroxypiparic 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, 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'-diphenyletherdicarboxylic Acid, adipic acid, sebacic acid, azelaic acid, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 4-methyl-1,2-cyclohexanedicarboxylic acid, dimer acid, etc. Aliphatic and alicyclic dibasic acids can be used.

  As a commercially available product of polyester diol, specifically, ODX-688 (DIC Co., Ltd. aliphatic polyester diol: adipic acid / neopentyl glycol / 1,6-hexanediol, number average molecular weight of about 2000), Vylon (registered) (Trademark) 220 (polyester diol manufactured by Toyobo Co., Ltd., number average molecular weight of about 2000).

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

  The above-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 “compounds having two hydroxy groups in an aromatic ring or cyclohexane ring” include hydroquinone, 2-methylhydroquinone, resorcinol, catechol, 2-phenylhydroquinone, cyclohexanedimethanol, tricyclodecanemethanol, 1,4-dihydroxycyclohexane, 1 , 3-dihydroxycyclohexane, 1,2-dihydroxycyclohexane, 1,3-adamantanediol, dicyclopentadiene dihydrate, 2,3-dihydroxybenzoic acid, 2,4-dihydroxybenzoic acid, 2,5-dihydroxy Carboxy group-containing diols 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'-tetramethyl-4,4'-biphenol, etc. can be used.

  Examples of the “compound having two hydroxy groups in the naphthalene skeleton” include 2,6-naphthalenediol, 1,4-naphthalenediol, 1,5-naphthalenediol, 1,8-naphthalenediol, and the like.

  The number average molecular weight of the diol 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.

  On the other hand, if it is greater than 30000, depending on the composition and structure of the “diol” and the composition and structure of the diamine component (or isocyanate component), which will be described later, phase separation may occur and the mechanical properties and colorless transparency may not be fully exhibited. .

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

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

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

(Divalent group having a structure represented by the formula (12))
A divalent group having a structure represented by the formula (12) will be described.

In Formula (12), R ₃ is a direct 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 fluorenylidene Represents a 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. X _{1 to} X ₈ may be the same as or different from each other, and each represents hydrogen, a halogen, or an alkyl group.

  Specific examples of the divalent group having a structure represented by the formula (12) are not particularly limited, but include diphenyl ether skeleton, diphenyl sulfone skeleton, 9-fluorenylidene diphenol skeleton, bisphenol A skeleton, bisphenol F skeleton, Examples thereof include an ethylene oxide adduct skeleton of bisphenol A, 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 (12). As raw materials for the divalent group having the structure represented by the formula (12), 4,4′-dihydroxydiphenyl ether, 4,4′-dihydroxydiphenylsulfone, 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 preferred is 4,4'-dihydroxydiphenyl ether or bisphenol A ethylene oxide adduct.

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 into the R ₁ position of the formula (10).

(Divalent group having a structure represented by the formula (13))

In formula (13), R ₄ represents a direct 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 fluorenylidene Represents a 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. X ₁ ′ to X ₈ ′ may be the same or different and each represents a hydrogen, halogen or alkyl group.

  Specific examples of the divalent group having the structure represented by the formula (13) are not particularly limited, but include a dicyclohexyl ether skeleton, a dicyclohexyl sulfone skeleton, a hydrogenated bisphenol A skeleton, a hydrogenated bisphenol F skeleton, and a hydrogenated bisphenol A. And the 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 both cyclohexane rings of the formula (13). As raw materials for the divalent group having the structure represented by the formula (13), 4,4′-dihydroxydicyclohexyl ether, 4,4′-dihydroxydicyclohexylsulfone, hydrogenated bisphenol A, hydrogenated bisphenol F, hydrogenated An ethylene oxide adduct of bisphenol A 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 R ₁ position of the formula (10).

  As an example of the structure of formula (10), a halide of cyclohexanetricarboxylic anhydride and a diol are reacted 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.

(Divalent group having a structure represented by formula (14))
The polyesterimide resin may further contain a structure represented by the formula (14) in the structural unit.

R _{2 in} Formula (10) and R ₂ ′ in Formula (14) will be described. R ₂ and R ₂ ′ are not particularly limited as long as they are each 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, R ₂ is a divalent group having a structure represented by the following formula (15), and R ₂ ′ is a divalent group having a structure represented by the following formula (16).

(Divalent group having a structure represented by the formula (15))
R ₂ in the formula (10) is preferably a divalent group having a structure represented by the formula (15) from the balance of heat resistance, flexibility, low hygroscopicity, and the like.

In formula (15), R ₅ is a direct 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. X _{9 to} X ₁₆ may be the same or different and each represents a hydrogen atom, a halogen atom, or an alkyl group.

(Divalent group having a structure represented by the formula (16))
R ₂ ′ in the formula (14) is preferably a divalent group having a structure represented by the formula (16) from the viewpoint of heat resistance, flexibility, low hygroscopic balance, and the like.

In Formula (16), R ₅ ′ is a direct 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. X ₉ ′ to X ₁₆ ′ may be the same or different and each represents a hydrogen, halogen or alkyl group.

In the formula (10) and the formula (14), “a divalent chain aliphatic group”, “a divalent cyclic aliphatic group”, or “a divalent aromatic group” is represented by the R ₂ position of the formula (10) And a corresponding diamine component or diisocyanate component is preferably used for introduction into the R ₂ ′ position of the formula (14). 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.

The diamine component of R _{2 of} formula (10) and R ₂ ′ of formula (14) 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 R ₂ and R ₂ ′ as a basic skeleton or a corresponding diisocyanate component 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) phene Nyl) hexafluoropropane, 2,2-bis (4-aminophenyl) hexafluoropropane, diaminoterphenyl and the like. These can be used in combination of two or more.

  The “cycloaliphatic diamine or the corresponding cycloaliphatic diisocyanate” is exemplified by a diamine compound such as trans-1,4-diaminocyclohexane, cis-1,4-diaminocyclohexane, 1,4-diamino. Cyclohexane (trans / cis mixture), 1,3-diaminocyclohexane, 4,4'-methylenebis (cyclohexylamine) (trans isomer, cis isomer, trans / cis mixture), isophorone diamine, 1,4-cyclohexane bis (methylamine) ), 2,5-bis (aminomethyl) bicyclo [2.2.1] heptane, 2,6-bis (aminomethyl) bicyclo [2.2.1] heptane, 3,8-bis (aminomethyl) tricyclo [5.2.1.0] decane, 1,3-diaminoadamantane, 4,4'-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, R ₂ in formula (10) and R ₂ ′ in formula (14) or a preferred diisocyanate component corresponding thereto are exemplified as diamine compounds. Then, p-phenylenediamine, 2,4-diaminotoluene, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether, 1,5-naphthalenediamine, o-tolidine, diaminoterphenyl, 4,4'- It is a residue derived from methylenebis (cyclohexylamine), isophoronediamine or 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.

  The polyimide according to the present invention preferably contains a fluorinated polyimide from the viewpoint of excellent transparency of the polyimide film and easy thermal correction by thermal shrinkage. As a content rate of a fluorine, it is more preferable that it is contained in the range of 1-40 mass% in a film, since the effect of this invention is large.

[2.6] Physical properties of optical film (total light transmittance)
The optical film of the present invention is a transparent polyimide film, and as a measure of transparency, the total light transmittance when a sample having a thickness of 100 μm is prepared is 80% or more. The total light transmittance is more preferably 85% or more, and still more preferably 90% or more. A higher total light transmittance is preferable because transparency increases. The description of the numerical value that the total light transmittance is 80% or more shows the preferable range.

  The total light transmittance of the optical film can be measured according to JIS K 7375-2008 for one optical film sample conditioned for 24 hours in an air-conditioned room at 23 ° C. and 55% RH. The measurement can measure the transmittance | permeability of visible region (range of 400-700 nm) using the spectrophotometer U-3300 of Hitachi High-Technologies Corporation.

  In order to make the total light transmittance 80% or more, it can be adjusted by selecting the kind of the polyimide.

(Yellow index value (YI value))
The optical film according to the present invention is a colorless polyimide film. As a measure of being colorless, the yellow index value (YI value) when a sample having a thickness of 100 μm is produced is 6.0 or less. More preferably, it exists in the range of 0.3-4.0, Most preferably, it exists in the range of 0.3-2.0. A smaller yellow index value (YI value) is preferable because coloring is less. The description of the numerical value that the yellow index value (YI value) is 6.0 or less indicates the preferable range.

  The YI value can be adjusted by selecting the type of polyimide.

  The yellow index value can be obtained according to YI (yellow index: yellowness index) of the film defined in JIS K 7103.

  As a method for measuring the yellow index value, a sample of a film is prepared, and a light source defined in JIS Z 8701 using a spectrophotometer U-3300 of Hitachi High-Technologies Corporation and the attached saturation calculation program, etc. The tristimulus values X, Y and Z of the color are obtained, and the yellow index value is obtained according to the definition of the following formula.

Yellow index value (YI value) = 100 (1.28X-1.06Z) / Y
(solubility)
The polyimide resin which concerns on this invention is a polyimide resin which melt | dissolves 1g or more in 100 g of dichloromethane at 25 degreeC. If the solubility is 1 g or more, it can be easily produced by the solution casting method. Higher solubility is preferred because it facilitates production by the solution casting method. The description of the numerical value that the solubility is 1 g or more shows an indication of a preferable range as the soluble polyimide resin.

  The solubility of the polyimide according to the present invention can be adjusted by selecting the type of polyimide resin used in the present invention.

  In order to make the polyimide resin soluble, it is effective to reduce the ratio of the structure of imide groups and aromatic hydrocarbons that work in the direction of increasing the planarity of the molecular skeleton of the polyimide. It is also effective to introduce structural isomers, bending groups, aliphatic groups or alicyclic groups instead of aromatic groups, and bulky skeletons such as fluorine atoms and fluorenes.

  Examples of compounds include alicyclic, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 1,2,3,4, 5-cyclohexanetetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentylacetic acid dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, (bicyclo [4.2.0] octane -3,4,7,8-tetracarboxylic dianhydride) bicyclo [2.2.1] heptanedimethanamine, the structure having a bending group is 2,3 ', 3,4'-biphenyltetracarboxylic Acid dianhydride, 3,4'-oxydiphthalic anhydride, 4,4 'oxydiphthalic anhydride, 3,3', 4,4'-benzophenone tetracarboxylic dianhydride, 3,3 ', 4,4 '-Diphenyl Lufone tetracarboxylic dianhydride, 2,2-bis (4- (3,4-dicarboxyphenoxy) phenyl) propane dianhydride, bis [4- (4-aminophenoxy) phenyl] sulfone, 2,2- Bis [4- (4-aminophenoxy) phenyl] propane, 1,3-bis (3-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) ) Benzene, bis (3-aminophenyl) sulfone, 3,3'-diaminobenzophenone, 3,4'-diaminodiphenyl ether.

  Examples of the compound containing a fluorine atom include 4,4 '-(hexafluoroisopropylidene) diphthalic anhydride, 2,2'-bis (trifluoromethyl) benzidine 2,2-bis (3-amino-4 -Hydroxyphenyl) hexafluoropropane, a compound containing a fluorene group includes 9,9-bis (4-amino-3-fluorophenyl) fluorene, 9,9-bis [4- (3,4-dicarboxyphenoxy). ) -Phenyl] fluorene anhydride, 9,9-bis [4- (3,4-dicarboxyphenoxy) -phenyl] fluorene anhydride, 9,9-Bis (3,4-dicarboxylicphenyl) fluorene Pilot fluorane Dihydride It is done.

(Haze value)
The optical film of the present invention preferably has a haze value of 4% or less from the viewpoint of high transparency of the optical film.

  The haze can be measured according to JIS K 7136 using a haze meter NDH-2000 (manufactured by Nippon Denshoku Industries Co., Ltd.). Measured under the conditions of 23 ° C. and 55% RH, the light source of the haze meter is a 5V · 9W halogen bulb, and the light receiving part is a silicon photocell (with a relative sensitivity filter).

[3] Additives of optical film The following additives can be further added to the optical film of the present invention.

(Inorganic fine particles)
The optical film of the present invention is preferably mixed with inorganic fine particles.

  When the mixing ratio of the inorganic fine particles into the optical film is 0.01% by mass or more, the slipperiness is improved. Accordingly, the flatness of the long-winding optical film is hardly deteriorated. Moreover, there exists an effect which prevents the haze increase of an optical film by setting it as 2.0 mass% or less.

  As the inorganic fine particles, the following inorganic compound fine particles are preferably used. Examples of fine particles of inorganic compounds include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate and calcium phosphate. Etc. Fine particles containing silicon are preferable in terms of low turbidity, and silicon dioxide is particularly preferable.

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

  A smaller average particle size of the primary particles of the inorganic fine particles is preferable from the viewpoint of less variation in haze value in the surface direction, which is an effect of the present invention. The average particle size of the primary particles is preferably 30 nm or less, and more preferably 10 nm or less.

  In addition, it is preferable that the inorganic fine particles are subjected to surface modification, and the surface is more hydrophobic from the viewpoint of improving the degree of dispersion in the film and less variation in haze value.

  As the hydrophobic treatment, the surface is modified with at least one compound selected from alkylsilanes having 5 to 21 carbon atoms, dimethylsiloxane, dimethylsiloxane cyclics, methacryloxysilane, and aminosilane. preferable.

  Inclusion of silica particles whose surface is modified with a compound having such a long-chain functional group or cyclic functional group improves the entanglement and interaction with the polyimide resin and facilitates the formation of secondary aggregates. Thus, the matte effect of the optical film itself can be enhanced.

  The content of these fine particles in the optical film is more preferably in the range of 0.01 to 1% by mass, and particularly preferably in the range of 0.05 to 0.5% by mass.

  In the case of an optical film having a multilayer structure formed by the co-casting method, it is preferable that the surface contains this amount of fine particles.

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

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

  Examples of resin fine particles include silicone resin, fluororesin, and acrylic resin. Silicone resins are preferable, and those having a three-dimensional network structure are particularly preferable. For example, Tospearl 103, 105, 108, 120, 145, 3120, and 240 (above, Momentive Performance Materials Japan) It is commercially available under the trade name (made by a limited liability company) and can be used.

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

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

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

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

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

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

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

  Add UV absorber to dope after dissolving UV absorber in alcohol such as methanol, ethanol, butanol, organic solvent such as dichloromethane, methyl acetate, acetone, 1,3-dioxolane or mixed solvent. Or may be added directly into the dope composition.

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

(Antioxidant)
Antioxidants are also referred to as deterioration inhibitors. When an electronic device or the like is placed in a high humidity and high temperature state, the optical film may be deteriorated.

  The antioxidant has a role of delaying or preventing the optical film from being decomposed by, for example, halogen remaining in the optical film or phosphoric acid of a phosphoric acid plasticizer. It is preferable to contain.

  As such an antioxidant, the compounds described in paragraph numbers 0108 to 0119 of JP2010-271619A can be preferably used.

  The addition amount of these compounds is preferably in the range of 1 ppm to 1.0% by mass ratio with respect to the optical film, and more preferably in the range of 10 to 1000 ppm.

(Phase difference control agent)
In order to improve the display quality of an image display device such as a liquid crystal display device, a retardation control agent is added to the optical film or an alignment film is formed to provide a liquid crystal layer. By combining the phase difference, the optical compensation ability can be imparted to the optical film.

  Examples of the phase difference controlling agent include aromatic compounds having two or more aromatic rings as described in European Patent No. 91656A2, and rod-shaped compounds described in JP-A-2006-2025. Two or more aromatic compounds may be used in combination. The aromatic ring of the aromatic compound is preferably an aromatic heterocyclic ring including an aromatic heterocyclic ring in addition to the aromatic hydrocarbon ring. The aromatic heterocycle is generally an unsaturated heterocycle. Of these, the 1,3,5-triazine ring described in JP-A-2006-2026 is preferable.

  The addition amount of these retardation control agents is preferably in the range of 0.5 to 20% by mass and preferably in the range of 1 to 10% by mass with respect to 100% by mass of the polyimide film resin. More preferred.

(Peeling accelerator)
A peeling accelerator may be added to the optical film of the present invention in order to improve the peelability during film production.

As additives for reducing the peel resistance of the optical film, there are many remarkable effects on surfactants, and preferable release agents include phosphate ester type surfactants, carboxylic acid or carboxylate type surfactants, A sulfonic acid or sulfonate surfactant and a sulfate ester surfactant are effective. A fluorine-based surfactant in which part of the hydrogen atoms bonded to the hydrocarbon chain of the surfactant is substituted with fluorine atoms is also effective. Examples of the release agent are given below.
_{RZ-1 C 8 H 17 O} -P (= O) - (OH) 2
_{RZ-2 C 12 H 25 O} -P (= O) - (OK) 2
_{RZ-3 C 12 H 25 OCH} 2 CH 2 O-P (= O) - (OK) 2
_{RZ-4 C 15 H 31 (} OCH 2 CH 2) 5 O-P (= O) - (OK) 2
_{RZ-5 {C 12 H 25} O (CH 2 CH 2 O) 5} 2 -P (= O) -OH
_{RZ-6 {C 18 H 35} (OCH 2 CH 2) 8 O} 2 -P (= O) -ONH 4
_{RZ-7 (t-C 4} H 9) 3 -C 6 H 2 -OCH 2 CH 2 O-P (= O) - (OK) 2
_{RZ-8 (iso-C 9} H 19 -C 6 H 4 -O- (CH 2 CH 2 O) 5 -P (= O) - (OK) (OH)
RZ-9 C ₁₂ H ₂₅ SO ₃ Na
RZ-10 C ₁₂ H ₂₅ OSO ₃ Na
RZ-11 C ₁₇ H ₃₃ COOH
RZ-12 C ₁₇ H ₃₃ COOH · N (CH ₂ CH ₂ OH) _{3
RZ-13 iso-C 8 H} 17 -C 6 H 4 -O- (CH 2 CH 2 O) 3 - (CH 2) 2 SO 3 Na
_{RZ-14 (iso-C 9} H 19) 2 -C 6 H 3 -O- (CH 2 CH 2 O) 3 - (CH 2) 4 SO 3 Na
RZ-15 sodium triisopropyl naphthalene sulfonate RZ-16 sodium tri-t-butyl naphthalene sulfonate RZ-17 C ₁₇ H ₃₃ CON (CH ₃ ) CH ₂ CH ₂ SO ₃ Na
_{RZ-18 C 12 H 25 -C} 6 H 4 SO 3 · NH 4
The addition amount of the peeling accelerator is preferably 0.05 to 5% by mass, more preferably 0.1 to 2% by mass, and most preferably 0.1 to 0.5% by mass with respect to the polyimide resin.

[4] Use of optical film The optical film containing the polyimide resin of the present invention can be used as a transparent film of an image display device. In particular, it can be preferably applied to a flexible image display device. The device to be applied is not particularly limited, and examples thereof include an organic electroluminescence (EL) image display device, a liquid crystal image display device (LCD), an organic photoelectric conversion device, a touch panel, a polarizing plate, and a retardation film. . From the viewpoint that the effect of the present invention can be obtained more efficiently, it is preferably used for a flexible television receiver such as an organic electroluminescence (EL) image display device and a liquid crystal image display device (LCD), and a front member for flexible display.

  EXAMPLES 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
<Preparation of polyimide film 101>
<Synthesis of general-purpose polyimide resin P>
The following tetracarboxylic dianhydride and diamine are reacted to obtain a polyamic acid which is an intermediate shown below. Then, the polyamic acid is dissolved in dichloromethane to prepare a dope, and then the dope is flowed on a film-forming support. It was dehydrated by heating on a support and imidized according to the following scheme. The weight average molecular weight of the polyimide resin P was 100,000.

(Main dope composition)
Dichloromethane 350 parts by weight Polyamic acid 100 parts by weight Matting agent (Aerosil R812, manufactured by Nippon Aerosil Co., Ltd.) 0.5 parts by weight (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. It was dehydrated and imidized at a drying temperature of 300 ° C. between casting and peeling.

(Peeling process)
On the stainless steel belt support, the solvent was evaporated until the residual solvent amount in the cast film (web) cast was 75% by mass, and then from the stainless steel belt support at a peeling tension of 180 N / m. It peeled.

(Preliminary drying process)
While the peeled cast film was conveyed by a roller, it was pre-dried so that the residual solvent amount was 15% by mass immediately before entering the tenter.

(Stretching process)
The pre-dried cast film was stretched 1.50 times in the width direction using a clip-type tenter while maintaining the temperature from the start of stretching to the end of stretching at 250 ° C. The residual solvent amount at the start of stretching was 15% by mass.

(Drying process)
The stretched film is dried at a drying temperature of 120 ° C. until the residual solvent amount is less than 0.5% by mass with a conveying tension of 100 N / m and a drying time of 15 minutes while being conveyed by a large number of rollers. A polyimide film 101 having a long film shape with a width of 1900 mm and a length of 5000 m was obtained.

<Preparation of polyimide film 102>

In addition, the acquisition place of the commercial item of said compound is as follows.
Acid anhydride 1: Daikin Industries, Ltd. Acid anhydride 2: Manac Co., Ltd. diamine 1: Daikin Industries, Ltd. diamine 2: Mitsui Chemicals Fine, Inc. (Preparation of polyimide solution A)
To a 4-necked flask equipped with a dry nitrogen gas inlet tube, a condenser, a Dean-Stark aggregator filled with toluene, and a stirrer, 2,2-bis (3,4-dicarboxyphenyl) -1,1,1, 25,59 g (57.6 mmol) of 3,3,3-hexafluoropropane dianhydride (acid anhydride 1) (manufactured by Daikin Industries, Ltd.) was added to N, N-dimethylacetamide (134 g) at room temperature under a nitrogen stream. Stir with.

  To this, 19.2 g (60 mmol) of 4,4′-diamino-2,2′-bis (trifluoromethyl) biphenyl (diamine 1) (manufactured by Daikin Industries, Ltd.) was added, and the mixture was stirred with heating at 80 ° C. for 6 hours. Thereafter, the external temperature was heated to 190 ° C., and water generated along with imidization was distilled off azeotropically with toluene. When heating, refluxing, and stirring were continued for 6 hours, generation of water was not observed. Subsequently, the mixture was heated for 7 hours while distilling off toluene. Further, after distilling off toluene, methanol was added for reprecipitation, and after drying the solid content, an 8% by mass dichloromethane solution was prepared to obtain polyimide solution A containing polyimide resin A. Prepared. The weight average molecular weight of the polyimide resin A was 140,000.

(Preparation of dope)
A main dope having the following composition was prepared. First, dichloromethane (boiling point 40 ° C.) was added to the pressure dissolution tank. The prepared polyimide solution A was charged into 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. The main dope was prepared by filtration using 244.

(Main dope composition)
Dichloromethane 350 parts by weight Polyimide solution A 100 parts by weight Matting agent (Aerosil R812, manufactured by Nippon Aerosil Co., Ltd.) 0.5 parts by weight (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 10 ° C.

(Peeling process)
On the stainless steel belt support, the solvent was evaporated until the residual solvent amount in the cast film (web) cast was 75% by mass, and then from the stainless steel belt support at a peeling tension of 180 N / m. It peeled.

(Preliminary drying process)
While the peeled cast film was conveyed by a roller, it was pre-dried so that the residual solvent amount was 15% by mass immediately before entering the tenter.

(Stretching process)
The pre-dried cast film was stretched 1.50 times in the width direction using a clip-type tenter while maintaining the temperature from the start of stretching to the end of stretching at 250 ° C. The residual solvent amount at the start of stretching was 15% by mass.

(Drying process)
The stretched film is dried at a drying temperature of 120 ° C. until the residual solvent amount is less than 0.5% by mass with a conveying tension of 100 N / m and a drying time of 15 minutes while being conveyed by a large number of rollers. A polyimide film 102 having a long film shape with a width of 1900 mm and a length of 5000 m was obtained.

<Preparation of polyimide film 103>
In the production of the polyimide film 102, a polyimide film 103 was produced in the same manner except that the main dope was changed to the following main dope.

(Main dope composition)
Dichloromethane 346.5 parts by mass Ethanol 3.5 parts by mass Polyimide solution A 100 parts by mass Matting agent (Aerosil R812, manufactured by Nippon Aerosil Co., Ltd.) 0.5 parts by mass <Preparation of polyimide films 104 to 106>
In the production of the polyimide film 103, polyimide films 104 to 106 were produced in the same manner except that the mass ratio of ethanol as the auxiliary solvent in the main dope was changed as shown in Table 1.

<Preparation of polyimide film 107>
In the production of the polyimide film 103, a polyimide film 107 was produced in the same manner except that methanol gas was circulated through the gas exposure device 35 shown in FIG. 2 and the casting film passed therethrough.

(Gas exposure device a)
Methanol gas: 500Pa, 300 ° C
Passing time: 90 seconds <Preparation of polyimide films 108-118>
In the production of the polyimide film 107, the polyimide film 107 was similarly changed except that the mass ratio of the auxiliary solvent used in combination with the main solvent and the type of gas in the gas exposure device 35 shown in FIG. 2 were changed as shown in Table 1. 108-118 were produced.

(Gas exposure device b)
Ethanol gas: 500Pa, 300 ° C
Passing time: 90 seconds (gas exposure device c)
Water vapor: 500Pa, 340 ° C
Passing time: 90 seconds <Preparation of polyimide film 119>
In the production of the polyimide film 103, a polyimide film 119 was produced in the same manner except that the blowing nozzle 38 shown in FIG.

(Blowing device a)
Ethanol: Liquid temperature 30 ° C
Spray distance: 15mm
Spraying time: 20 seconds <Production of polyimide films 120 to 130>
In the production of the polyimide film 119, the polyimide film 120 was similarly prepared except that the mass ratio of the auxiliary solvent used in combination with the main solvent and the type of the solution in the spray nozzle 38 shown in FIG. 3 were changed as shown in Table 1. ~ 130 were made.

(Blowing device b)
Methanol: Liquid temperature 30 ° C
Spray distance: 15mm
Spraying time: 20 seconds (Blowing device c)
Water: Liquid temperature 30 ° C
Spray distance: 15mm
Spraying time: 20 seconds <Preparation of polyimide film 131>
In the production of the polyimide film 103, a polyimide film 131 was produced in the same manner except that the casting film was immersed in a tank in which water was circulated by the immersion device 36 shown in FIG.

(Immersion device a)
Water: Liquid temperature 30 ° C
Immersion time: 90 seconds <Preparation of polyimide films 132 to 142>
In the production of the polyimide film 131, the polyimide film 132 was similarly changed except that the mass ratio of the auxiliary solvent used in combination with the main solvent and the type of the solution in the immersion device 36 shown in FIG. 3 were changed as shown in Table 2. -142 were made.

(Immersion device b)
Ethanol: Liquid temperature 30 ° C
Immersion time: 90 seconds (immersion device c)
Methanol: Liquid temperature 30 ° C
Immersion time: 90 seconds <Preparation of polyimide films 143 to 151>
In the production of the polyimide film 107, the auxiliary solvent used in combination with the main solvent is changed from ethanol to methanol, and as shown in Table 2, using the exposure device, spraying device, and immersion device, methanol exposure, ethanol exposure, water vapor exposure Polyimide films 143 to 151 were produced in the same manner except that ethanol spraying, methanol spraying, water spraying, water soaking, ethanol soaking and methanol soaking were performed.

<Preparation of polyimide films 152-160>
In the production of the polyimide film 107, the polyimide resin was changed to the following resin B, and as shown in Table 2, using the exposure device, spraying device, and immersion device, methanol exposure, ethanol exposure, water vapor exposure, ethanol spraying, methanol Polyimide films 152 to 160 were produced in the same manner except that spraying, water spraying, water immersion, ethanol immersion and methanol immersion were performed.

(Preparation of polyimide solution B)
In a four-necked flask equipped with a dry nitrogen gas introduction tube, a condenser, a Dean-Stark aggregator filled with toluene, and a stirrer, 17.87 g (57.6 mmol) of the acid anhydride 2 (manac) was added. , N-dimethylacetamide (134 g) and stirred at room temperature under a nitrogen stream.

  11.53 g (60 mmol) of the diamine 2 (manufactured by Mitsui Chemical Fine Co., Ltd.) was added thereto, and the mixture was heated and stirred at 80 ° C. for 6 hours. Thereafter, the external temperature was heated to 190 ° C., and water generated along with imidization was distilled off azeotropically with toluene. When heating, refluxing, and stirring were continued for 6 hours, generation of water was not observed. Subsequently, the mixture is heated for 7 hours while distilling off toluene. Further, after distilling off toluene, methanol is added for reprecipitation, and after drying the solid content, an 8% by mass dichloromethane solution is prepared to obtain polyimide solution B containing polyimide resin B. Prepared. The weight average molecular weight of the polyimide resin B was 130,000.

≪Evaluation≫
The following evaluation was implemented using the produced polyimide films 101-160.

(1) Measurement of solution haze Solution haze measured the haze with the haze meter NDH-2000 (made by Nippon Denshoku Industries Co., Ltd.) after producing the said main dope based on JISK7136. . Specifically, measurement is performed under the conditions of 23 ° C., 55% RH, and optical path length of 1 cm. The light source of the haze meter is a halogen bulb of 5 V and 9 W, and the light receiving part is a silicon photocell (with a relative visibility filter). As a result, the haze of the dope was measured.

(2) Scaly unevenness The polyimide film after film formation was visually observed, and the degree of occurrence of scaly unevenness was evaluated according to the following evaluation criteria.

○: Scaly unevenness is not observed ×: Scaly unevenness is observed (3) Film haze A polyimide film after film formation is subjected to haze meter NDH-2000 (Nippon Denshoku Industries Co., Ltd.) in accordance with JIS K 7136. Haze was measured. Specifically, the measurement was performed under conditions of 23 ° C. and 55% RH, the light source of the haze meter was a halogen bulb of 5 V and 9 W, the light receiving portion was a silicon photocell (with a relative visibility filter), and a polyimide film The haze was measured.

  Tables 1 and 2 show the configuration of the polyimide film and the evaluation results.

  From the results of Tables 1 and 2, the method for producing a polyimide film of the present invention produced no film-like unevenness when the cast film was peeled off, and the film haze was low. It turns out that it is excellent as a method.

  Further, a polyimide film using a general-purpose polyimide resin is strongly colored due to imidization by heating, has a yellow index value exceeding 6.0, and is not suitable for an optical film.

Example 2
<Preparation of polyimide film 201>
A polyimide film 201 was produced in the same manner as in the production of the polyimide film 105 of Example 1, except that the dry film thickness was adjusted to 40 μm.

<Preparation of polyimide film 202>
In the production of the polyimide film 201, a polyimide film 202 was produced in the same manner except that the main dope was changed to the following.

(Main dope composition)
Dichloromethane 339 parts by mass Ethanol 11 parts by mass Water 1.0 part by mass Polyimide solution A 100 parts by mass Matting agent (Aerosil R812, manufactured by Nippon Aerosil Co., Ltd.) 0.5 parts by mass <Preparation of polyimide films 203 to 222>
In the production of the polyimide film 202, polyimide films 203 to 222 were produced in the same manner except that the type and amount of the auxiliary solvent and the amount of water contained in the dope were changed.

  Using the produced polyimide films 201 to 222, evaluation of solution haze, scaly unevenness and film haze was performed in the same manner as in Example 1.

  Table 3 shows the composition and evaluation results of the polyimide film.

  From the results in Table 3, the method for producing a polyimide film of the present invention is excellent as a method for producing a film for optical use because the unevenness of scaly generated when peeling a cast film is not observed and the film haze is low. I understand that

11 Endless belt (support)
21 Dope 22 Casting film 35 Exposure device 36 Immersion device 38 Spray nozzle (spray device)
51 Tension regulating roller 57 Auxiliary roller C1 Air curtain C2 Air curtain Z1 Preheating zone Z2 Stretching zone Z3 Cooling zone

Claims (5)

A method for producing an optical film comprising a soluble polyimide resin as a main component and casting a dope containing dichloromethane as a main solvent on a film-forming support,
The solution haze of the dope is 1.0% or less, and
A method for producing an optical film, comprising a step of supplying a polar solvent to an interface between the casting film and the film-forming support. The dope contains an alcohol solvent as an auxiliary solvent so that the alcohol mass ratio in the total solvent is 3.0% or less, and
The method for producing an optical film according to claim 1, wherein the step of supplying the polar solvent is a step of exposing the cast film in an atmosphere of water or an alcohol solvent. The dope contains an alcohol solvent as an auxiliary solvent so that the alcohol mass ratio in the total solvent is 3.0% or less, and
The step of supplying the polar solvent is a step of spraying water or an alcohol solvent on the casting film or immersing the casting film in the water or an alcohol solvent. The manufacturing method of the optical film of description. The dope contains an alcohol solvent as an auxiliary solvent so that the alcohol mass ratio in the total solvent exceeds 3.0%, and
The method for producing an optical film according to claim 1, wherein the step of supplying the polar solvent is a step of containing water in the dope. An apparatus for producing an optical film comprising a soluble polyimide resin as a main component and casting a dope containing dichloromethane as a main solvent on a film-forming support to form a cast film,
The solution haze of the dope is 1.0% or less, and
An apparatus for producing an optical film, comprising: a polar solvent supply unit that supplies a polar solvent to an interface between the casting film and the film-forming support.

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