JP6981423B2 - Optical film manufacturing method - Google Patents

Description

The present invention relates to a method for producing an optical film containing any one of a polyimide resin, a cycloolefin resin, and a polyarylate resin.

In recent years, as display devices have become more flexible and bendable, there is a demand for further thinning of optical films mounted on display devices. As a method for producing a thin film optical film (hereinafter, also referred to as a thin film film), a solution casting film forming method is generally known, and among them, a manufacturing method using a cellulose acylate resin has been widely proposed. .. When producing a thin film with high productivity, for example, in the melt casting film forming method, it is impossible to cast the diluted resin, and it is difficult to eliminate web unevenness (film thickness unevenness). .. However, in the solution casting film forming method, since the resin can be diluted and cast, the leveling effect is obtained even under the influence of environmental changes (temperature, wind) immediately after casting, and the surface is good ( It is possible to manufacture a thin film (with reduced defects such as streaks and uneven film thickness).

Here, as a method for producing an optical film having a good planar shape using a cellulose acylate resin, for example, there is a method disclosed in Patent Documents 1 to 3. In Patent Document 1, when the speed at which the dope of the optical film is discharged from the casting die is V1 (m / min) and the moving speed of the support is V2 (m / min), the speed difference (V2-V1) is obtained. By setting the above to a specific range, it is possible to manufacture an optical film with good flatness with almost no unevenness in the width direction (streak-like unevenness) or unevenness in the longitudinal direction (thickness unevenness called horizontal stage). It has become. Further, in Patent Document 2, the extensional stress applied to the ribbon-like dope at the tip of the lip of the casting die is set in ^{the range of 0 to 39 × 10 2} Pa, so that the thickness unevenness occurs in the casting direction of the film. This prevents streaks and makes it possible to manufacture photosensitive materials for photographs with good flatness and films used for optical applications. Further, in Patent Document 3, foam is caught in the end portion of the resin film due to a difference in the ejection speed of the dope ejected from the ejection port depending on the position in the longitudinal direction of the ejection port of the casting die. Based on the speculation that a failure (horizontal unevenness) may occur due to the vibration of the support, the dope discharge speed at both ends of the discharge port of the casting die and the dope discharge speed at the center of the discharge port of the casting die. The ratio of is close to 1.

Japanese Patent No. 4517671 (see claim 1, paragraphs [0007], [0011], etc.) Japanese Unexamined Patent Publication No. 2001-71338 (see claim 1, paragraph [0009], etc.) WO2012-0566619 (see claim 1, paragraphs [0025] to [0040], etc.)

By the way, conventionally, a cellulose acylate resin (for example, a cellulose triacetate resin) has been used as a material for an optical film from the viewpoint of adhesion to a polarizing element at the time of producing a polarizing plate (see Patent Documents 1 to 3). However, due to recent improvements in adhesive technology, optical films using resins other than cellulose ester resins are now being adopted. In particular, from the viewpoint of low moisture permeability and electrode processability, there is an increasing need for a thin film using a polyimide resin, a cycloolefin resin, and a polyarylate resin.

Here, when the methods of Patent Documents 1 to 3 were applied when producing a thin film using a polyimide resin, a cycloolefin resin, and a polyarylate resin, the position due to uneven peeling of the cast film from the support was observed. It was found that the phase difference unevenness occurred and the horizontal step unevenness occurred in the flow film. The inventor of the present application speculates the reason as follows.

In the solution casting method, the casting film is dried on the support and peeled off from the support, but the casting film shrinks when it is dried on the support. At this time, in the film formation using the cellulose acylate resin, the adhesive force between the support and the hypersalivation film is larger than the contraction force of the flow film, so that the flow film is less likely to be peeled off from the support. For this reason, although a large tension is required when the cast film is peeled off, the peeling of the cast film is stable, and the peeling position in the width direction of the cast film varies in the transport direction of the cast film, so-called peeling unevenness. It rarely happens.

On the other hand, in the film formation using the polyimide resin or the polyarylate resin, the adhesive force between the support and the hypersalivation film is much smaller than the contraction force of the hypersalivation film, so that the peeling is not stable. Therefore, as shown in FIG. 9, the end portion 101b, which is more likely to flutter than the central portion 101a in the width direction of the casting film 101, is more likely to be peeled off from the support 100 before the central portion 101a, resulting in uneven peeling. .. The same applies to the film formation using the cycloolefin resin, and the adhesion between the support 100 and the hypersalivation film 101 is smaller than the contraction force of the hypersalivation film 101, so that the peeling is not stable and the same peeling as described above is performed. Unevenness occurs. In this way, when the peeling unevenness of the casting film 101 occurs, the peeling tension is not evenly applied in the width direction of the casting film 101, so that the orientation direction of the molecules is at the central portion 101a and the end portion 101b of the casting film 101. Disperses. As a result, phase difference unevenness occurs in the width direction of the casting film 101.

Further, the discharge of the dope containing the polyimide resin, the cycloolefin resin, and the polyarylate resin is less stable than the discharge of the dope containing the cellulose acylate resin due to the difference in the resin type, and the disturbance (for example, vibration of the support) during the discharge is caused. It is affected and easily shakes. As a result, as shown in FIG. 10, horizontal unevenness (film thickness unevenness in the casting direction) is likely to occur in the casting film 101 on the support 100.

The present invention has been made to solve the above problems, and an object thereof is to cast an optical film using any of a polyimide resin, a cycloolefin resin, and a polyarylate resin. To provide a method for manufacturing an optical film capable of stabilizing peeling of a film from a support and reducing peeling unevenness, thereby reducing phase difference unevenness in the width direction and reducing horizontal unevenness. be.

The above object of the present invention is achieved by the following manufacturing method.

That is, the method for producing an optical film according to one aspect of the present invention is a method for producing an optical film by a solution casting film forming method.
A dope containing any of a polyimide resin, a cycloolefin resin, and a polyarylate resin and a solvent is discharged from a casting die, cast on a moving support, and the cast dope is dried and poured. The casting process to form a film and
Including a peeling step of peeling the cast film from the support.
The dope ejection speed from the end of the casting width of the casting die is V _1E (m / min), and the ejection speed of the dope from the center of the casting width of the casting die is V _1C (m / min). When the moving speed of the support is V ₂ (m / min), the method for producing an optical film is characterized by simultaneously satisfying the following conditional equations (1) and (2);
(1) V ₂ > V _1C
(2) (V ₂ / V _1E )> (V ₂ / V _1C )
Is.

According to the above manufacturing method, in the film formation of an optical film using any of a polyimide resin, a cycloolefin resin, and a polyarylate resin, uneven peeling of the cast film from the support is reduced in the width direction. The phase difference unevenness of the above can be reduced, and the horizontal step unevenness can be reduced.

It is explanatory drawing which shows the schematic structure of the optical film manufacturing apparatus which concerns on embodiment of this invention. It is a flowchart which shows the flow of the manufacturing process of the said optical film. It is explanatory drawing which enlarges and shows the main part of FIG. It is a vertical sectional view which shows one structural example of the casting die of the said manufacturing apparatus. It is explanatory drawing which shows the other structural example of the above-mentioned flow-through die schematically. It is a horizontal sectional view which shows the other structure of the above-mentioned flow-through die. It is explanatory drawing which shows typically the difference of the dope discharge rate by the difference of the slit gap of the casting die. It is explanatory drawing for demonstrating the calculation method of a dope discharge rate. It is explanatory drawing which shows the mode that peeling unevenness occurs when peeling from a support of a casting film. It is a perspective view schematically showing the flow-through film in which horizontal unevenness occurred.

An embodiment of the present invention will be described below with reference to the drawings. In this specification, when the numerical range is expressed as A to B, the numerical range includes the values of the lower limit A and the upper limit B.

The method for producing an optical film of the present embodiment is a method for producing an optical film by a solution casting film forming method, in which a dope containing any one of a polyimide resin, a cycloolefin resin, and a polyarylate resin and a solvent is used. A casting step of discharging from a casting die, spreading on a moving support, and drying the spread dope to form a casting film, and a peeling step of peeling the casting film from the support. And include. The dope discharge rate from the end of the flow width of the flow die is V _1E (m / min), and the discharge rate of the dope from the center of the flow width of the flow die is V _1C (m / min). When the moving speed of the support is V ₂ (m / min), the following conditional equations (1) and (2) are satisfied at the same time. That is,
(1) V ₂ > V _1C
(2) (V ₂ / V _1E )> (V ₂ / V _1C )
Is.

In addition, in this specification, the casting width end portion of the casting die is the end portion in the width direction including the edge of the casting film on the support (the width is the full width of the casting film). Refers to the region where the dope forming (10% or less) is discharged. Further, the central portion of the casting width of the casting die refers to a region in the casting die that discharges the dope forming the central portion including the center in the width direction of the casting film. The width of the central portion of the casting width in the casting direction is not particularly limited, but here, for example, a width of 10% or less of the total width of the casting film is considered.

By satisfying the conditional expression (1), the dope discharged from the center of the casting width of the casting die is pulled (stretched) in the casting direction (moving direction of the support) by the movement of the support. .. Then, by satisfying the conditional expression (2), the dope discharged from the casting width end portion of the casting die is pulled further in the casting direction than the dope discharged from the casting width central portion. As a result, even when an optical film is formed using any of a polyimide resin, a cycloolefin resin, and a polyarylate resin, the strength of the widthwise end portion of the cast film increases on the support. When the cast film is peeled off from the support, the end portion is less likely to flutter. Therefore, the end portion of the cast film is less likely to be peeled off from the support before the central portion, and variation in the peeling position in the width direction of the cast film, that is, peeling unevenness can be reduced. By reducing such peeling unevenness, the peeling tension is evenly applied in the width direction of the casting film, so that the orientation direction of the molecules is reduced between the end and the center of the casting film. Therefore, it is possible to reduce the occurrence of retardation unevenness in the width direction of the casting film.

Further, the conditional expression (2) is satisfied, that is, the dope discharged from the spreading width end of the casting die is pulled further in the casting direction than the dope discharged from the center of the casting width. , The dope discharged from the end of the flow width is stable and less likely to shake. As a result, even when a dope containing any of a polyimide resin, a cycloolefin resin, and a polyarylate resin is cast on the support, the entire dope shakes due to the influence of disturbance (for example, vibration of the support). It is possible to suppress the unevenness of the film thickness that occurs in the flow direction, that is, the unevenness of the horizontal step.

In the manufacturing method of the present embodiment, by satisfying the conditional equations (1) and (2), the dope discharged from the casting die is slightly pulled in the casting direction (discharge direction) in the entire width. By positively differentizing the dope discharge rate in the width direction, horizontal unevenness may occur even in film formation using resins other than cellulose ester resin, such as polyimide resin, cycloolefin resin, and polyarylate resin. And phase difference unevenness can be reduced. From this, the manufacturing method of the present embodiment in which the dope discharge rate is positively different in the width direction is a film forming using a cellulose ester resin, and the dope discharge rate is made uniform in the width direction. It can be said that the technical idea is completely different from the manufacturing method of 3.

From the viewpoint of surely reducing the phase difference unevenness and the horizontal step unevenness, it is desirable that the manufacturing method of the present embodiment further satisfies the following conditional expression (3). That is,
(3) 3 <(V ₂ / V _1C ) ≤ 10
Is.

When _{the value of V 2} / V _1C is lower than the lower limit, the action of stretching the dope discharged from the center of the casting width of the casting die in the casting direction by the movement of the support becomes smaller, so that the casting film It becomes difficult to increase the strength of the central part. For this reason, the central portion of the cast film tends to flutter when peeled from the support, causing peeling unevenness, and it becomes difficult to obtain the effect of reducing the phase difference unevenness. On the other hand, when _{the value of V 2} / V _1C exceeds the upper limit, the moving speed of the support becomes too fast with respect to the ejection speed of the dope, and the support tends to vibrate, and as a result, the casting die The dope discharged from the surface is likely to shake, and horizontal unevenness is likely to occur.

Further, from the viewpoint of reducing phase difference unevenness and horizontal step unevenness in a well-balanced manner, it is desirable that the manufacturing method of the present embodiment further satisfies the following conditional expression (4). That is,
(4) 1.05 ≦ (V ₂ / V _1E ) / (V ₂ / V _1C ) ≦ 1.5
Is.

When the value of (V ₂ / V _1E ) / (V ₂ / V _1C ) is below the lower limit, _{the difference between V 1E} and V _1C becomes small, and V _1E is relatively slower than V _{1C and spreads.} It becomes difficult to obtain the effect of the present embodiment in which the strength of the edge portion of the film is increased to reduce the peeling unevenness and the phase difference unevenness is reduced. On the other hand, if the value of (V ₂ / V _1E ) / (V ₂ / V _1C ) exceeds the upper limit, _{the difference between V 1E} and V _1C becomes too large, and the dope discharged from the casting die tends to shake. Therefore, horizontal unevenness is likely to occur.

A more desirable range of V ₂ / V _1C is indicated by the following conditional expression (3'), and a more desirable range of (V ₂ / V _1E ) / (V ₂ / V _1C ) is given by the following conditional expression (4). '). That is, from the viewpoint of surely reducing both the phase difference unevenness and the horizontal step unevenness, it is desirable that the manufacturing method of the present embodiment further satisfies the following conditional expressions (3') and (4'). That is,
(3') 4.6 ≤ (V ₂ / V _1C ) ≤ 5.0
(4') 1.2 ≤ (V ₂ / V _1E ) / (V ₂ / V _1C ) ≤ 1.3
Is.

_{The ejection speed V 1E of the} dope may be made slower than the ejection speed V _1C by changing the gap of the slit of the casting die in which the dope is discharged in the casting width direction. _{That is, V 1E} <V _1C may be realized by widening the slit gap of the casting die at the casting width end portion rather than the casting width central portion. _{Since V 1E} <V _1C can be easily realized by controlling the slit gap, it becomes easy to satisfy the above-mentioned conditional expression (2), (4) or (4'), and the effect of the above-mentioned embodiment can be achieved. It will be easy to obtain.

[Solution casting film formation method]
Hereinafter, the method for manufacturing the optical film of the present embodiment will be specifically described. FIG. 1 is an explanatory diagram showing a schematic configuration of the optical film manufacturing apparatus 1 of the present embodiment. Further, FIG. 2 is a flowchart showing the flow of the manufacturing process of the optical film. The method for producing an optical film of the present embodiment is a method for producing an optical film by a solution casting film forming method, and as shown in FIG. 2, a stirring preparation step (S1), a casting step (S2), and a peeling step. (S3), a first drying step (S4), a stretching step (S5), a second drying step (S6), a cutting step (S7), an embossing step (S8), and a winding step (S9) are included. Hereinafter, each step will be described.

<Stirring preparation process>
In the stirring preparation step, at least the resin and the solvent are stirred in the stirring tank 51 of the stirring device 50 to prepare a dope to be cast on the support 3 (endless belt). Here, as the resin, any one of a polyimide resin, a cycloolefin resin, and a polyarylate resin is used. As the solvent, a mixed solvent of a good solvent and a poor solvent is used.

<Hypersalivation process>
In the casting step, the dope prepared in the stirring preparation step is sent to the casting die 2 by a conduit through a pressurized metering gear pump or the like, and is transferred indefinitely on the support 3 made of a rotary drive stainless steel endless belt. Dope is spread from the casting die 2 to the casting position. Then, the cast dope is dried on the support 3 to form the cast film 5 (web). The inclination of the casting die 2, that is, the ejection direction of the dope from the casting die 2 to the support 3, is 0 ° to 90 ° at an angle with respect to the normal of the surface of the support 3 (the surface on which the dope is spread). It may be appropriately set so as to be within the range of. The details of the hypersalivation die 2 will be described later.

The support 3 is held by a pair of rolls 3a and 3b and a plurality of rolls (not shown) located between them. One or both of the rolls 3a and 3b is provided with a drive device (not shown) for applying tension to the support 3, whereby the support 3 is used in a tensioned state.

In the casting step, the casting film 5 formed by the dope spread on the support 3 is heated on the support 3, and the casting film 5 can be peeled from the support 3 by the peeling roll 4. Evaporate the solvent until. To evaporate the solvent, there are a method of blowing wind from the web side, a method of transferring heat from the back surface of the support 3 with a liquid, a method of transferring heat from the front and back surfaces by radiant heat, and the like, which are used individually or in combination as appropriate. Just do it.

<Peeling process>
In the above casting step, the casting film 5 is dried and solidified or cooled and solidified on the support 3 until the casting film 5 has a peelable film strength, and then in the peeling step, the casting film 5 has self-supporting property. It is peeled off by the peeling roll 4 while it is left in place.

The amount of residual solvent in the cast film 5 on the support 3 at the time of peeling is preferably in the range of 50 to 120% by mass depending on the strength of the drying conditions, the length of the support 3, and the like. When peeling at a time when the amount of residual solvent is larger, if the casting film 5 is too soft, the flatness at the time of peeling is impaired, and wrinkles and vertical streaks are likely to occur due to the peeling tension. The amount of residual solvent is determined. The amount of residual solvent is defined by the following formula.

Residual solvent amount (mass%) = (mass before heat treatment of web-mass after heat treatment of web) / (mass after heat treatment of web) × 100
Here, the heat treatment when measuring the residual solvent amount means that the heat treatment is performed at 115 ° C. for 1 hour.

<First drying step>
The cast film 5 peeled off from the support 3 is dried by the drying device 6. In the drying device 6, the cast film 5 is transported by a plurality of transport rolls arranged in a staggered pattern when viewed from the side surface, and the cast film 5 is dried between them. The drying method in the drying device 6 is not particularly limited, and the cast film 5 is generally dried using hot air, infrared rays, a heating roll, microwaves, or the like. From the viewpoint of simplicity, a method of drying the cast film 5 with hot air is preferable. The first drying step may be performed as needed.

<Stretching process>
In the stretching step, the cast film 5 dried by the drying device 6 is stretched by the tenter 7. The stretching direction at this time is one of a film transport direction (MD direction; Machine Direction), a width direction perpendicular to the transport direction in the film surface (TD direction; Transverse Direction), and both of these directions. In the stretching step, a tenter method in which both side edges of the casting film 5 are fixed with clips or the like and stretched is preferable in order to improve the flatness and dimensional stability of the film. In the tenter 7, drying may be performed in addition to stretching. In the stretching step, by stretching the casting film 5 in both the MD direction and the TD direction, the casting film 5 can be stretched (diagonally stretched) in a direction diagonally intersecting the MD direction and the TD direction. ..

<Second drying process>
The cast film 5 stretched by the tenter 7 is dried by the drying device 8. In the drying device 8, the cast film 5 is transported by a plurality of transport rolls arranged in a staggered pattern when viewed from the side surface, and the cast film 5 is dried between them. The drying method in the drying device 8 is not particularly limited, and the cast film 5 is generally dried using hot air, infrared rays, a heating roll, microwaves, or the like. From the viewpoint of simplicity, a method of drying the cast film 5 with hot air is preferable.

The flow film 5 is dried by the drying device 8 and then conveyed as an optical film F toward the winding device 11.

<Cutting process, embossing process>
A cutting portion 9 and an embossing portion 10 are arranged in this order between the drying device 8 and the winding device 11. In the cutting portion 9, a cutting step is performed in which both ends in the width direction thereof are cut by a slitter while conveying the formed optical film F. In the optical film F, the portion remaining after cutting both ends constitutes a product portion to be a film product. On the other hand, the portion cut from the optical film F is recovered by a shooter and reused as a part of the raw material for film formation.

After the cutting step, both ends of the optical film F in the width direction are embossed (knurled) by the embossing portion 10. The embossing process is performed by pressing a heated embossing roller against both ends of the optical film F. Fine irregularities are formed on the surface of the embossing roller, and by pressing the embossing roller against both ends of the optical film F, the irregularities are formed on both ends. By such embossing, winding misalignment and blocking (sticking between films) in the next winding process can be suppressed as much as possible.

<Winling process>
Finally, the optical film F having been embossed is wound by the winding device 11 to obtain the original winding (film roll) of the optical film F. That is, in the winding step, a film roll is manufactured by winding the optical film F around the winding core while conveying it. As the winding method of the optical film F, a commonly used winder may be used, and there are methods for controlling the tension such as a constant torque method, a constant tension method, a taper tension method, and a program tension control method with a constant internal stress. You can use them properly. The winding length of the optical film F is preferably 1000 to 7200 m. Further, the width at that time is preferably 1000 to 3200 mm, and the film thickness is preferably 10 to 60 μm.

[Details of hypersalivation die]
Next, the details of the casting die 2 that discharges the dope in the casting step will be described. The dope discharge rate from the end of the flow width of the flow die 2 is V _1E (m / min), and the discharge rate of the dope from the center of the flow width of the flow die 2 is V _1C (m / min). When the moving speed of the support 3 is V ₂ (m / min), in the present embodiment, the casting die is satisfied so as to satisfy the above-mentioned conditional equations (1) to (4) in the casting step. The dope is discharged from 2 toward the support 3, and the support 3 is moved (running). Thereby, the phase difference unevenness and the horizontal step unevenness can be reduced, and the detailed reason thereof is as described above.

Here, FIG. 3 schematically shows the relationship between _{the dope discharge rates V 1E} and V _1C in the casting process of the present embodiment and the moving speed V _{2 of the support 3.} The length of the arrow in the figure corresponds to the magnitude of the velocity. In the present embodiment, the dope discharge speeds V _1E and V _1C are slower than the moving speed of the support 3, and the dope discharge speed V _1E is further slower than the dope discharge speed V _1C. As a result, the draw ratio indicating the ratio between the moving speed of the support 3 and the dope discharge speed is different in the flow width direction. That is, in this embodiment, (V ₂ / V _1E )> (V ₂ / V _1C ). In the present embodiment, V ₂ / V _1E is also referred to as a draw ratio VA, and V ₂ / V _1C is also referred to as a draw ratio VB.

As a method of making the draw ratio VA and the draw ratio VB different in the flow width direction, for example, any one of the following three methods can be adopted.

(A) Method of changing the internal structure of the casting die FIG. 4 is a vertical cross-sectional view showing a configuration example of the casting die 2. The dope prepared in the dope preparation kettle is supplied to the casting die 2 via, for example, a pump (not shown), and is housed in a recess inside the casting die 2, that is, in a manifold 2 m. The above manifold 2m is originally designed so that the dope spreads uniformly inside the casting die 2 from the casting width center portion 2a to the casting width end portion 2b, but in the present embodiment, the flow is performed. The shape of the manifold 2m is designed so that the dope is concentrated and flows in the center portion 2a of the spread width rather than the end portion 2b of the spread width. With such a design of the manifold 2m, it is possible to realize _{V 1C} > V _1E by increasing the discharge amount per unit time of the dope from the flow width center portion 2a as compared with the flow spread width end portion 2b. Thereby, the draw ratio VA and the draw ratio VB can be made different (VA> VB can be satisfied).

(B) Method Using Pumps with Different Dope Supply Capabilities FIG. 5 is an explanatory diagram schematically showing another configuration example of the flow casting die 2. The flow die 2 flows through _{two types of dope supply ports 2A 1} and dope supply ports 2A ₂ corresponding to the flow width center portion 2a and the flow extension width end portion 2b, and each dope supply port 2A ₁ and 2A _{2. Dope communication passages 2B 1} and 2B ₂ for guiding the dope into the manifold 2 m are provided. The dope supply port 2A ₁ is connected to the first pump P _1, and the dope supply port 2A ₂ is connected to the second pump P _2.

For example, (doped supply amount per unit time) first pump P ₁ of the dope supply capacity is higher than the second doped supply capacity of the pump P _2, doped supply ports 2A ₁ and doped with each other by the first pump P ₁ The amount of dope supplied into the manifold 2 m via the passage 2B _{1 per unit time is supplied into the manifold 2 m by the second pump P 2} via the dope supply port 2A ₂ and the dope _{communication passage 2B 2.} More than the amount of dope supplied per unit time. Therefore, by setting the dope supply capacity of the first pump P ₁ and the second pump P _{2 as described above, V 1C} > V _1E is realized as the relationship of the dope discharge rate from the flow die 2. , The draw ratio VA and the draw ratio VB can be made different.

In FIG. 5, in the casting die 2, the inner diameters of the dope communication passages 2B ₁ and 2B _{2 communicating with the dope supply ports 2A 1} and 2A _{2 are set to the dope supply of the first pump P 1} and the second pump P ₂ . The inner diameters of the _{dope communication passages 2B 1} and 2B ₂ may be the same as long as the dope supply capacities of _{the first pump P 1} and the second pump P ₂ are different, although they are different to correspond to the capacities. ..

(C) Method for Controlling Slit Gap of Casting Die FIG. 6 is a horizontal cross-sectional view showing still another configuration of the casting die 2. The casting die 2 has a slit 31 that serves as a doping port. The slit 31 is formed of a pair of lips. One lip is a flexible lip 32 having low rigidity and being easily deformed, and the other lip is a fixed lip 33. The slit 31 includes a casting width central portion 2a and a casting width end portion 2b for discharging the dope.

Further, the casting die 2 is provided with a plurality of heat bolts 34 for adjusting the width of the slit 31 (the opening length in the dope casting direction, hereinafter also referred to as “slit gap”). The plurality of heat bolts 34 are arranged side by side at substantially constant intervals in the casting width direction (longitudinal direction of the slit 31) of the casting die 2.

The casting die 2 is provided with a block (not shown) provided with an embedded electric heater and a cooling medium passage corresponding to each heat bolt 34, and each heat bolt 34 penetrates each block. While the block is constantly air-cooled, the input of the embedded electric heater is increased or decreased to raise or lower the temperature of the block, and the heat bolt 34 is thermally expanded or contracted, whereby the flexible lip 32 can be displaced to adjust the slit gap.

Here, FIG. 7 schematically shows the difference in the dope discharge rate due to the difference in the slit gap of the casting die 2. When the dope flow rate within a unit time is constant (the moving speed of the support 3 is _{constant at V 2} ), if the slit gap is wide, the dope discharge speed V _1-1 becomes slow and the slit gap becomes large. If it is narrow, the dope discharge rate V _1-2 becomes high (V _1-2 > V _1-1 ). Therefore, as shown in FIG. 6, each heat bolt 34 is controlled to control the slit gap so that the slit gap of the casting die 2 is wider at the casting width end portion 2b than at the casting width central portion 2a. _{As a result, V 1C} > V _1E can be easily realized as the discharge rate of the dope, whereby the draw ratio VA and the draw ratio VB can be made different.

〔resin〕
In the present embodiment, as the resin used for producing the optical film, that is, the resin contained in the dope, any resin of polyimide resin, cycloolefin resin, and polyarylate resin can be used.

<Polyimide resin>
As the polyimide, a polyimide having a repeating unit represented by the following general formula (I) (hereinafter referred to as polyimide (A)) can be used. The polyimide (A) can be obtained by imidizing a polyamic acid having a repeating unit represented by the following general formula (I') (hereinafter referred to as polyamic acid (A')).

In the general formula (I), R is an aromatic hydrocarbon ring or an aromatic heterocycle, or a tetravalent aliphatic hydrocarbon group or an alicyclic hydrocarbon group having 4 to 39 carbon atoms. Φ is a divalent aliphatic hydrocarbon group having 2 to 39 carbon atoms, an alicyclic hydrocarbon group, an aromatic hydrocarbon group, or a group consisting of a combination thereof, and as a linking group, −O−, At least 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-} It may contain one group.

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

Examples of the aromatic heterocycle represented by R include a silol ring, a furan ring, a thiophene ring, an oxazole ring, a pyrrole ring, a pyridine ring, a pyridazine ring, a pyrimidine ring, a pyrazine ring, a triazine ring, and an oxadiazole 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 (carbazole ring) Any one or more of the carbon atoms constituting the dibenzosilol ring, dibenzofuran ring, dibenzothiophene ring, benzothiophene ring or dibenzofuran ring), any one or more of the carbon atoms constituting the Ring replaced with a nitrogen atom, benzodifuran ring, benzodithiophene ring, aclysine ring, benzoquinoline ring, phenazine ring, phenanthridine ring, phenanthroline ring, cyclazine ring, kindrin ring, tepenidine ring, quinindrin ring, triphenodithiadin Ring, triphenodioxazine ring, phenanthrazine ring, anthrazine ring, perimidine ring, naphthofranc ring, naphthothiophene ring, naphthodifuran ring, naphthodithiophene ring, anthrafuran ring, anthradifuran ring, anthrathiophene ring, anthradithiophene ring , Thiophene ring, phenoxatiin 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 butane-1,1,4,4-triyl group and octane-1,1,8,8-triyl group. Examples include groups such as decane-1,1,10,10-triyl groups.

Examples of the tetravalent alicyclic hydrocarbon group having 4 to 39 carbon atoms represented by R include cyclobutane-1,2,3,4-tetrayl group and cyclopentane-1,2,4,5. -Tetrayl group, cyclohexane-1,2,4,5-tetrayl group, bicyclo [2.2.2] octo-7-en-2,3,5,6-tetrayl group, bicyclo [2.2.2] Octane-2,3,5,6-tetrayl group, 3,3', 4,4'-dicyclohexyltetrayl group, 3,6-dimethylcyclohexane-1,2,4,5-tetrayl group, 3,6- Examples thereof include groups such as diphenylcyclohexane-1,2,4,5-tetrayl group.

Examples of the divalent aliphatic hydrocarbon group having 2 to 39 carbon atoms having or not having the above-mentioned bonding group represented by Φ include a group represented by the following structural formula.

In the above structural formula, n represents the number of repeating units, preferably 1 to 5, and more preferably 1 to 3. Further, X is an alkanediyl group having 1 to 3 carbon atoms, that is, a methylene group, an ethylene group, a trimethylene group and 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 having or not having the above-mentioned bonding group represented by Φ include a group represented by the following structural formula.

Examples of the divalent aromatic hydrocarbon group having 2 to 39 carbon atoms having or not having the above-mentioned bonding group represented by Φ include a group represented by the following structural formula.

Examples of the group composed of a combination of an aliphatic hydrocarbon group represented by Φ, an alicyclic hydrocarbon group and an aromatic hydrocarbon group include a group represented by the following structural formula.

The group represented by Φ is preferably a divalent aromatic hydrocarbon group having 2-39 carbon atoms or a combination of the aromatic hydrocarbon group and the aliphatic hydrocarbon group, particularly preferably. , A group represented by the following structural formula is preferable.

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

The polyimide (A) is prepared by reacting an aromatic, aliphatic or alicyclic tetracarboxylic acid or a derivative thereof with a diamine or a derivative thereof to prepare a polyamic acid (A'), and the polyamic acid (A') is used. Obtained by imidization.

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

Examples of the derivative of diamine include diisocyanate and diaminodisilanes. Of the diamines or derivatives thereof, diamines are preferable.

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, and 1,2,4,5-cyclohexanetetracarboxylic acid. , Bicyclo [2.2.2] Oct-7-en-2,3,5,6-tetracarboxylic acid, Bicyclo [2.2.2] Octane-2,3,5,6-tetracarboxylic acid, etc. Can be mentioned.

Examples of the aliphatic 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 alicyclic tetracarboxylic acids. The alkyl group moiety is preferably an alkyl group having 1 to 5 carbon atoms, and more preferably an alkyl group having 1 to 3 carbon atoms.

Examples of the aliphatic tetracarboxylic dianhydride include 1,2,3,4-butanetetracarboxylic dianhydride. Examples of the alicyclic tetracarboxylic dianhydride include 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,4,5-cyclopentanetetracarboxylic dianhydride, 1,2. , 4,5-Cyclohexanetetracarboxylic dianhydride, Bicyclo [2.2.2] Oct-7-en-2,3,5,6-tetracarboxylic dianhydride, Bicyclo [2.2.2] Examples thereof include octane-2,3,5,6-tetracarboxylic dianhydride and 2,3,5-tricarboxycyclopentylacetichydride dianhydride. Particularly preferred is 1,2,4,5-cyclohexanetetracarboxylic dianhydride. In general, in polyimide containing an aliphatic diamine as a constituent component, polyamic acid and diamine, which are intermediate products, form a strong salt, so that a solvent having a relatively high salt solubility (for example, cresol) is used to increase the molecular weight. , N, N-dimethylacetamide, γ-butyrolactone, N-methyl-2-pyrrolidone, etc.). However, even in a polyimide containing an aliphatic diamine as a component, when 1,2,4,5-cyclohexanetetracarboxylic acid dianhydride is a component, the polyamic acid and the salt of the diamine are bound by a relatively weak bond. Therefore, it is easy to increase the molecular weight, and it is easy to obtain a flexible film.

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

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

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

Examples of such other tetracarboxylic acids or derivatives thereof include pyromellitic acid, 3,3', 4,4'-biphenyltetracarboxylic acid, 2,3,3', 4'-biphenyltetracarboxylic acid, 2, 2-bis (3,4-dicarboxyphenyl) propane, 2,2-bis (2,3-dicarboxyphenyl) propane, 2,2-bis (3,4-dicarboxyphenyl) -1,1,1 , 3,3,3-hexafluoropropane, 2,2-bis (2,3-dicarboxyphenyl) -1,1,1,3,3,3-hexafluoropropane, bis (3,4-dicarboxyphenyl) Phenyl) sulfone, bis (3,4-dicarboxyphenyl) ether, bis (2,3-dicarboxyphenyl) ether, 3,3', 4,4'-benzophenone tetracarboxylic acid, 2,2', 3, 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 derivatives thereof (particularly dianhydride); ethylene tetracarboxylic acid and the like. Examples thereof include aliphatic tetracarboxylic acids having 1 to 3 carbon atoms and derivatives thereof (particularly dianhydride).

The diamine may be an aromatic diamine, an aliphatic diamine, or a mixture thereof. In the present embodiment, the "aromatic diamine" represents a diamine in which an amino group is directly bonded to an aromatic ring, and an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, or the like is part of the structure thereof. (For example, a halogen atom, a sulfonyl group, a carbonyl group, an oxygen atom, etc.) may be contained. The "aliphatic diamine" represents a diamine in which an amino group is directly bonded to an aliphatic hydrocarbon group or an alicyclic hydrocarbon group, and an aromatic hydrocarbon group or other substituent (a part of the structure thereof) is represented. For example, it may contain a halogen atom, a sulfonyl group, a carbonyl group, an oxygen atom, etc.).

Examples of the aromatic diamine include p-phenylenediamine, m-phenylenediamine, 2,4-diaminotoluene, 2,6-diaminotoluene, benzidine, o-tridin, m-trizine, and 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'-diamino Diphenylmethane, 4,4'-diaminodiphenylsulfone, 3,4'-diaminodiphenylsulfone, 4,4'-diaminobenzophenone, 2,2-bis (4- (4-aminophenoxy) phenyl) propane, 2,2- Bis (4- (2-methyl-4-aminophenoxy) phenyl) propane, 2,2-bis (4- (2,6-dimethyl-4-aminophenoxy) phenyl) propane, 2,2-bis (4- (4-Aminophenoxy) phenyl) hexafluoropropane, 2,2-bis (4- (2-methyl-4-aminophenoxy) phenyl) hexafluoropropane, 2,2-bis (4- (2,6-dimethyl) dimethyl) -4-Aminophenoxy) phenyl) hexafluoropropane, 4,4'-bis (4-aminophenoxy) biphenyl, 4,4'-bis (2-methyl-4-aminophenoxy) biphenyl, 4,4'-bis (2,6-dimethyl-4-aminophenoxy) biphenyl, 4,4'-bis (3-aminophenoxy) biphenyl, bis (4- (4-aminophenoxy) phenyl) sulfone, bis (4- (2-methyl) -4-Aminophenoxy) phenyl) sulfone, bis (4- (2,6-dimethyl-4-aminophenoxy) phenyl) sulfone, bis (4- (4-aminophenoxy) phenyl) ether, bis (4- (2) -Methyl-4-aminophenoxy) phenyl) ether, bis (4- (2,6-dimethyl-4-aminophenoxy) phenyl) ether, 1,4-bis (4-aminophenoxy) benzene, 1,4-bis (2-Methyl-4-aminophenoxy) benzene, 1,4-bis (2,6-dimethyl-4-aminophenoxy) benzene, 1,3-bis (4-ami) Nophenoxy) Benzene, 1,3-bis (2-methyl-4-aminophenoxy) benzene, 1,3-bis (2,6-dimethyl-4-aminophenoxy) benzene, 2,2-bis (4-amino) Benzene) propane, 2,2-bis (2-methyl-4-aminophenyl) propane, 2,2-bis (3-methyl-4-aminophenyl) propane, 2,2-bis (3-ethyl-4-aminophenyl) propane Aminophenyl) propane, 2,2-bis (3,5-dimethyl-4-aminophenyl) propane, 2,2-bis (2,6-dimethyl-4-aminophenyl) propane, 2,2-bis (4) -Aminophenyl) Hexafluoropropane, 2,2-bis (2-methyl-4-aminophenyl) hexafluoropropane, 2,2-bis (2,6-dimethyl-4-aminophenyl) hexafluoropropane, α, α'-bis (4-aminophenyl) -1,4-diisopropylbenzene (bisaniline P), 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 (bisaniline M), 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, 9,9-bis (4-aminophenyl) fluorene, 9 , 9-bis (2-methyl-4-aminophenyl) fluorene, 9,9-bis (2,6-dimethyl-4-aminophenyl) fluorene, 1,1-bis (4-aminophenyl) cyclopentane, 1, , 1-bis (2-methyl-4-aminophenyl) cyclopentane, 1,1-bis (2,6-dimethyl-4-aminophenyl) cyclopentane, 1,1-bis (4-aminophenyl) cyclohexane, 1,1-bis (2-methyl-4-aminophenyl) cyclohexane, 1,1-bis (2,6-dimethyl-4-aminophenyl) cyclohexane, 1,1-bis (4-aminophenyl) 4-methyl -Cyclohexane, 1,1-bis (4-aminophenyl) norbornane, 1,1-bis (2-me) Chill-4-aminophenyl) norbornan, 1,1-bis (2,6-dimethyl-4-aminophenyl) norbornan, 1,1-bis (4-aminophenyl) adamantan, 1,1-bis (2-methyl) -4-Aminophenyl) adamantan, 1,1-bis (2,6-dimethyl-4-aminophenyl) adamantan, 1,4-phenylenediamine, 3,3'-diaminobenzophenone, 2,2-bis (3-2-bis) Aminophenyl) Hexafluoropropane, 3-aminobenzylamine, 9,9-bis (4-amino-3-fluorophenyl) fluorene, 2,2-bis (3-amino-4-methylphenyl) hexafluoropropane, 1 , 3-bis (3-aminophenoxy) benzene, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, bis [4- (3-aminophenoxy) phenyl] sulfone, 1,3-bis [ 2- (4-Aminophenyl) -2-propyl] benzene, bis (2-aminophenyl) sulfide, bis (4-aminophenyl) sulfide, 1,3-bis (3-aminopropyl) tetramethyldisiloxane, 4 , 4'-diamino-3,3'-dimethyldiphenylmethane, 3,3'-diaminodiphenylmethane, 4,4'-ethylenedianiline, 4,4'-methylenebis (2,6-diethylaniline), 2,2- Bis [4- (4-aminophenoxy) phenyl] hexafluoropropane, bis [4- (4-aminophenoxy) phenyl] sulfone, 2,2-bis (3-amino-4-hydroxyphenyl) hexafluoropropane, 5 , 5'-(hexafluoroisopropylidene) di-o-toluidine, 2,2'-bis (trifluoromethyl) benzidine, 4,4'-diaminooctafluorobiphenyl, resorcinolbis (3-aminophenyl) ether, Resolsinol bis (4-aminophenyl) ether, bis (3-aminophenyl) sulfone, bis (4-aminophenyl) sulfone (trade name: SEIKACURE-S, manufactured by Seika Co., Ltd.), 4,4'-thiodianiline, 3,4'-Diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenylmethane, 2,7-diaminofluorene, 2,5-dimethyl-1,4-phenylenediamine, 4,4'-methylenebis (2-Ethyl-6-methylaniline), 2,3,5,6-tetramethyl-1,4-phenylenediami , M-xylylene diamine, p-xylylene diamine, 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl, 4,4'-diamino-3,3', 5,5' -Tetraisopropyldiphenylmethane, 3,3-diaminodiphenylsulfone, 1- (4-aminophenyl) -2,3-dihydro-1,3,3-trimethyl-1H-inden-5-amine, 1,4-bis ( Examples thereof include 2-amino-isopropyl) benzene and 1,3-bis (2-amino-isopropyl) benzene.

Examples of the aliphatic diamine include ethylenediamine, hexamethylenediamine, polyethylene glycol bis (3-aminopropyl) ether, polypropylene glycol bis (3-aminopropyl) ether, 1,3-bis (aminomethyl) cyclohexane (cis form and cis form). Mix of trans form), 1,4-bis (aminomethyl) cyclohexane (mixture of cis form and trans form), isophoronediamine, norbornandiamine, siloxanediamine, 4,4'-diaminodicyclohexylmethane, 3,3'- Dimethyl-4,4'-diaminodicyclohexylmethane, 3,3'-diethyl-4,4'-diaminodicyclohexylmethane, 3,3', 5,5'-tetramethyl-4,4'-diaminodicyclohexylmethane, 2 , 3-Bis (aminomethyl) -bicyclo [2.2.1] heptane, 2,5-bis (aminomethyl) -bicyclo [2.2.1] heptane, 2,6-bis (aminomethyl) -bicyclo [2.2.1] Heptane, 2,2-bis (4,4'-diaminocyclohexyl) propane, 2,2-bis (4,4'-diaminomethylcyclohexyl) propane, bis (aminomethyl) norbornan (heterosexual) Bicyclo [2.2.1] heptanedimethaneamine (isomer mixture), 4,4'-methylenebis (2-methylcyclohexylamine) (isomer mixture), 4,4'-methylenebis (cyclohexylamine) ) (Isomeric mixture) and the like.

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

Examples of the diaminodisilanes that are diamine derivatives include trimethylsilylated aromatic or aliphatic diamines obtained by reacting the above aromatic or aliphatic diamines with chlorotrimethylsilane.

The above diamines and their derivatives 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%.

The polyamic acid can be obtained by polymerizing at least one of the tetracarboxylic acids and at least one of the diamines in a suitable solvent.

The polyamic acid ester is formed by diesterifying the tetracarboxylic acid dianhydride with an alcohol such as methanol, ethanol, isopropanol, or n-propanol, and the obtained diester is used in an appropriate solvent. It can be obtained by reacting with a diamine compound. Further, the polyamic acid ester can also be obtained by esterifying the carboxylic acid group of the polyamic acid obtained as described above by reacting with the alcohol as described above.

The reaction between the tetracarboxylic dianhydride and the diamine compound can be carried out under conventionally known conditions. The order and method of adding the tetracarboxylic dianhydride and the diamine compound are not particularly limited. For example, a polyamic acid can be obtained by sequentially adding a tetracarboxylic dianhydride and a diamine compound to a solvent and stirring the mixture at an appropriate temperature.

The amount of the diamine compound is usually 0.8 mol or more, preferably 1 mol or more, relative to 1 mol of the tetracarboxylic dianhydride. On the other hand, it is usually 1.2 mol or less, preferably 1.1 mol or less. By setting the amount of the diamine compound in such a range, the yield of the obtained polyamic acid can be improved.

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

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

Examples of the polymerization solvent used in this reaction include hydrocarbon solvents such as hexane, cyclohexane, heptane, benzene, toluene, xylene and mesitylen; carbon tetrachloride, methylene chloride, chloroform, 1,2-dichloroethane, chlorobenzene and di. Halogenated hydrocarbon solvents such as chlorobenzene and fluorobenzene; ether solvents such as diethyl ether, tetrahydrofuran, 1,4-dioxane, methoxybenzene, alkylene glycol monoalkyl ethers and alkylene glycol dialkyl ethers; ketone solvents such as acetone and methyl ethyl ketone Amid solvents such as N, N-dimethylformamide, N, N-dimethylacetamide, N, N-diethylacetamide and N-methyl-2-pyrrolidone; Aproton polar solvents such as dimethylsulfoxide and γ-butyrolactone; , Picolin, lutidine, quinoline, isoquinolin, sulfolane and other heterocyclic solvents; phenolic solvents such as phenol and cresol; other solvents such as alkylcarbitol acetate and benzoic acid ester, but are particularly limited. is not it. As the polymerization solvent, only one kind may be used, or two or more kinds of solvents may be mixed and used.

As the terminal group of the polyamic acid, an acid anhydride group and an amino group can be arbitrarily selected by excessively using either a tetracarboxylic acid dianhydride or a diamine compound at the time of the polymerization reaction.

When the terminal group is an acid anhydride terminal, the acid anhydride terminal may be left as it is without further treatment, or it may be hydrolyzed to obtain a dicarboxylic acid. Further, an alcohol having 4 or less carbon atoms may be used as an ester. Further, a monofunctional amine compound and / or an isocyanate compound may be used to seal the ends. The amine compound and / or isocyanate compound used here is not particularly limited as long as it is a monofunctional primary amine compound and / or isocyanate compound. For example, aniline, methylaniline, dimethylaniline, trimethylaniline, ethylaniline, diethylaniline, triethylaniline, aminophenol, methoxyaniline, aminobenzoic acid, biphenylamine, naphthylamine, cyclohexylamine, phenylisocyanate, xylylene isocyanate, cyclohexyl isocyanate. , Methylphenyl isocyanate, trifluoromethylphenyl isocyanate and the like.

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

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

In the thermal imidization method, the polyamic acid in the polymerization solvent is heat-treated in a temperature range of, for example, 80 to 300 ° C. for 1 to 200 hours to proceed with imidization. Further, the temperature range is preferably 150 to 200 ° C., and by setting the temperature to 150 ° C. or higher, imidization can be reliably advanced and completed, while by setting the temperature to 200 ° C. or lower, the solvent or the like can be used. It is possible to prevent an increase in resin concentration due to oxidation of unreacted raw materials and volatilization of 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 co-boiling solvent, for example, aromatic hydrocarbons such as toluene, xylene and solvent naphtha, and alicyclic hydrocarbons such as cyclohexane, methylcyclohexane and dimethylcyclohexane can be used. When an azeotropic solvent is used, the amount added thereof is about 1 to 30% by mass, preferably 5 to 20% by mass, based on the total amount of the organic solvent.

On the other hand, in the chemical imidization method, a known ring-closing catalyst is added to the polyamic acid in the polymerization solvent to promote imidization. As the ring-closing catalyst, pyridine may usually be used, but in addition to this, for example, a substituted or unsubstituted nitrogen-containing heterocyclic compound, an N-oxide compound of a nitrogen-containing heterocyclic compound, a substituted or unsubstituted amino acid compound, etc. Examples include aromatic hydrocarbon compounds or aromatic heterocyclic compounds having a hydroxy group, in particular 1,2-dimethylimidazole, N-methylimidazole, N-benzyl-2-methylimidazole, 2-methylimidazole, 2-ethyl-. Lower alkyl imidazoles such as 4-methylimidazole and 5-methylbenzimidazole, imidazole derivatives such as N-benzyl-2-methylimidazole, isoquinoline, 3,5-dimethylpyridine, 3,4-dimethylpyridine, 2,5-dimethyl Substituted pyridines such as pyridine, 2,4-dimethylpyridine and 4-n-propylpyridine, p-toluenesulfonic acid and the like can be preferably used. The amount of the ring closure catalyst added is preferably 0.01 to 2 times equivalent, particularly about 0.02 to 1 times equivalent with respect to the amic acid unit of the polyamic acid. By using a ring-closing catalyst, the physical characteristics of the obtained polyimide, particularly elongation and breaking resistance, may be improved.

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

Further, in the polyimide, a film in which a polyamic acid solution is cast is heat-treated (thermal imidization method), or a polyamic acid solution mixed with a ring-closing catalyst is cast on a support to imidize the film. It can also be obtained in the form of a film by (chemical imidization method). Specific examples of the ring-closed catalyst include aliphatic tertiary amines such as trimethylamine and triethylenediamine and heterocyclic tertiary amines such as isoquinoline, pyridine and picoline, which are selected from heterocyclic tertiary amines. It is preferable to use at least one amine. The content of the ring-closing catalyst with respect to the polyamic acid is preferably in the range of 0.5 to 8.0 in the content (mol) of the ring-closing catalyst / the content (mol) of the polyamic acid.

As the polyamic acid or polyimide configured as described above, those having a weight average molecular weight of 30,000 to 1,000,000 are used from the viewpoint of forming a film.

Further, when the polyimide obtained by imidizing the polyamic acid as described above is cast, the imidization ratio of the polyamic acid at the time of casting is preferably 10 to 100%. Here, the imidization ratio can be obtained from the peak obtained by Fourier transform infrared spectroscopy by the following equation.
Equation (A): (C / D) × 100 / (E / F)
In the above formula (A), C ^{represents the absorption peak height of 1370 cm -1} of the polyamic acid or polyimide dope, D represents the absorption peak height ^{of 1500 cm -1 of the polyamic acid or polyimide dope, and E.} Represents the absorption peak height of 1370 cm ^-1 of the polyimide film, and F represents the absorption peak height ^{of 1500 cm -1 of the polyimide film.}

By setting the imidization rate of the polyamic acid at the time of casting to 10 to 100%, a polyimide film having a lower elastic modulus than the method of forming a casting film using a polyamic acid having an imidization rate of 0% and then imidizing the film. Can be obtained.

<Cycloolefin resin>
Examples of the cycloolefin resin (cycloolefin polymer) include a monomer polymer or a copolymer having a structure represented by the following general formula (S).

In the formula, R ^{1 to} R ⁴ are independently hydrogen atom, hydrocarbon group, halogen atom, hydroxy group, carboxy group, acyloxy group, aryloxycarbonyl group, alkoxycarbonyl group, alkoxy group, cyano group and amide group, respectively. , An imide group, a silyl group, or a polar group (ie, a halogen atom, a hydroxy group, an acyloxy group, an aryloxycarbonyl group, an alkoxycarbonyl group, an alkoxy group, a cyano group, an amide group, an imide group, or a silyl group). It is a hydrocarbon group.

However, in R ^{1 to} R ⁴ , two or more of them may be bonded to each other to form an unsaturated bond, a monocyclic ring or a polycyclic ring, and the monocyclic or polycyclic ring has a double bond. Alternatively, an aromatic ring may be formed. R ¹ and R ² or R ³ and R ⁴ may form an alkylidene group. p and m are integers greater than or equal to 0.

In the above general formula (S), the ^{hydrocarbon group represented by R 1} and R ³ is preferably a hydrocarbon group having 1 to 10 carbon atoms, more preferably 1 to 4, and particularly preferably 1 to 2 carbon atoms.

It is preferable that R ² and R ⁴ are hydrogen atoms or monovalent organic groups, ^{and at least one of R 2} and R ⁴ shows a polar group having a polarity other than a hydrogen atom and a hydrocarbon group, and m is 0. The integer of ~ 3 and p are integers of 0 to 3, more preferably m + p = 0 to 4, still more preferably 0 to 2, and particularly preferably m = 1 and p = 0.

The specific monomer having m = 1 and p = 0 is preferable in that the obtained cycloolefin resin has a high glass transition temperature and excellent mechanical strength. The glass transition temperature referred to here is a value obtained by a method based on JIS K 7121-2012 using DSC (Differential Scanning Colorimetry).

Examples of the polar group of the specific monomer include a carboxy group, a hydroxy group, an alkoxycarbonyl group, an allyloxycarbonyl group, an amino group, an amide group, a cyano group and the like, and these polar groups include a linking group such as a methylene group. It may be bonded via.

Further, a hydrocarbon group to which a divalent organic group having a polarity such as a carbonyl group, an ether group, a silyl ether group, a thioether group and an imino group is bonded as a linking group is also mentioned as a polar group.

Among these, a carboxy group, a hydroxy group, an alkoxycarbonyl group or an allyloxycarbonyl group is preferable, and an alkoxycarbonyl group or an allyloxycarbonyl group is particularly preferable.

Further, as the monomer in which at least one of ^{R 2} and R ⁴ _{is a polar group represented by the formula − (CH 2} ) _n COOR, the obtained cycloolefin resin has a high glass transition temperature, low hygroscopicity, and various materials. It is preferable in that it has excellent adhesion to and from.

In the above formula for the specific polar group, R is a hydrocarbon group having 1 to 12 carbon atoms, more preferably 1 to 4, particularly preferably 1 to 2 hydrocarbon groups, preferably an alkyl group.

Specific examples of the copolymerizable monomer include cycloolefin resins such as cyclobutene, cyclopentene, cycloheptene, cyclooctene, and dicyclopentadiene.

The number of carbon atoms of the cycloolefin is preferably 4 to 20, and more preferably 5 to 12.

In the present embodiment, the cycloolefin resin may be used alone or in combination of two or more.

The preferred molecular weight of the cycloolefin resin is 0.2 to ⁵ _{cm 3 / g at intrinsic viscosity [η] inh} , more preferably 0.3 to ³ cm 3 / g, and particularly preferably 0.4 to 1.5 cm ³ / g. The polystyrene-equivalent number average molecular weight (Mn) measured by gel permeation chromatography (GPC) is 8,000 to 100,000, more preferably 1,000 to 80,000, and particularly preferably 12,000 to 50,000, and the weight average molecular weight (Mw). Is 2000 to 300,000, more preferably 30,000 to 250,000, and particularly preferably 40,000 to 200,000.

Since the intrinsic viscosity [η] _inh , the number average molecular weight and the weight average molecular weight are within the above ranges, the heat resistance, water resistance, chemical resistance and mechanical properties of the cycloolefin resin and the molding process of the optical film of the present embodiment are obtained. The sex is good.

The glass transition temperature (Tg) of the cycloolefin resin is usually 110 ° C. or higher, preferably 110 to 350 ° C., more preferably 120 to 250 ° C., and particularly preferably 120 to 220 ° C. A case where the Tg is 110 ° C. or higher is preferable because deformation is unlikely to occur due to use under high temperature conditions or secondary processing such as coating and printing.

On the other hand, when the Tg is 350 ° C. or lower, it is possible to avoid the case where the molding process becomes difficult and reduce the possibility that the resin is deteriorated by the heat during the molding process.

For the cycloolefin resin, for example, a specific hydrocarbon-based resin described in JP-A-9-221577 and JP-A-10-287732, or a known heat, as long as the effect of the present embodiment is not impaired. Plastic resins, thermoplastic elastomers, rubbery polymers, organic fine particles, inorganic fine particles, etc. may be blended, and specific wavelength dispersants, sugar ester compounds, antioxidants, peeling accelerators, rubber particles, plasticizers, ultraviolet rays, etc. may be blended. It may contain an additive such as an absorbent.

Further, as the cycloolefin resin, a commercially available product can be preferably used. Examples of commercially available products are sold by JSR Corporation under the trade names of ARTON (registered trademark) G, ARTON F, ARTON R, and ARTON RX. Further, it is commercially available from Nippon Zeon Corporation under the trade name of ZEONOR (registered trademark) ZF14, ZF16, ZEONEX (registered trademark) 250 or ZEONEX 280, and these can be used.

<Polyarylate resin>
The polyarylate resin contains at least an aromatic dialcohol component unit and an aromatic dicarboxylic acid component unit.

(Aromatic dialcohol component unit)
The aromatic dialcohol for obtaining the aromatic dialcohol component unit is preferably a bisphenol represented by the following formula (1), and more preferably a bisphenol represented by the following formula (1').

L in the general formulas (1) and (1') is a divalent organic group. The divalent organic group is preferably a single bond, an alkylene group, -S-, -SO-, -SO _2- , -O-, -CO- or -CR _{1 R 2-} (R ₁ and R ₂ are each other. Combine to form an aliphatic or aromatic ring).

The alkylene group is preferably an alkylene group having 1 to 10 carbon atoms, and examples thereof include a methylene group, an ethylene group, an isopropanol group and the like. The alkylene group may further have a substituent such as a halogen atom or an aryl group.

-CR ₁ R _2- R ₁ and R ₂ of − are bonded to each other to form an aliphatic ring or an aromatic ring, respectively. The aliphatic ring is preferably an aliphatic hydrocarbon ring having 5 to 20 carbon atoms, and preferably a cyclohexane ring which may have a substituent. The aromatic ring is an aromatic hydrocarbon ring having 6 to 20 carbon atoms, and is preferably a fluorene ring which may have a substituent. _{Examples of −CR 1} R ₂ − forming a cyclohexane ring which may have a substituent include cyclohexane-1,1-diyl group, 3,3,5-trimethylcyclohexane-1,1-diyl group and the like. included. _{Examples of −CR 1} R ₂ − forming a fluorene ring which may have a substituent include a fluoreneyl group represented by the following formula.

The R of the general formulas (1) and (1') can independently be an alkyl group having 1 to 5 carbon atoms or an aryl group having 6 to 10 carbon atoms. n is an independently integer of 0 to 4, preferably an integer of 0 to 3.

Examples of bisphenols in which L is an alkylene group include 1,1-bis (4-hydroxyphenyl) methane, 1,1-bis (4-hydroxyphenyl) ethane, and 1,1-bis (4-methyl-2). -Hydroxyphenyl) methane, 1,1-bis (3,5-dimethyl-4-hydroxyphenyl) methane, 2,2-bis (4-hydroxyphenyl) -4-methylpentane, 2,2-bis (4-) Hydroxyphenyl) propane (BPA), 2,2-bis (3-methyl-4-hydroxyphenyl) propane (BPC), 2,2-bis (3,5-dimethyl-4-hydroxyphenyl) propane (TMBPA), etc. Is included. Among them, 2,2-bis (4-hydroxyphenyl) propane (BPA), 2,2-bis (3-methyl-4-hydroxyphenyl) propane (BPC), 2,2-bis (3,5-dimethyl-). Isopropyridene-containing bisphenols such as 4-hydroxyphenyl) propane (TMBPA) are preferred.

Examples of bisphenols with L of -S-, -SO- or -SO _2- are bis (4-hydroxyphenyl) sulfone, bis (2-hydroxyphenyl) sulfone, bis (3,5-dimethyl-4). -Hydroxyphenyl) sulfone (TMBPS), bis (3,5-diethyl-4-hydroxyphenyl) sulfone, bis (3-methyl-4-hydroxyphenyl) sulfone, bis (3-ethyl-4-hydroxyphenyl) sulfone, Bis (4-hydroxyphenyl) sulfide, bis (3,5-dimethyl-4-hydroxyphenyl) sulfide, bis (3,5-diethyl-4-hydroxyphenyl) sulfide, bis (3-methyl-4-hydroxyphenyl) Includes sulfide, bis (3-ethyl-4-hydroxyphenyl) sulfide, 2,4-dihydroxydiphenyl sulfone and the like. Examples of bisphenols with L -O- include 4,4'-dihydroxydiphenyl ethers. Examples of bisphenols with L -CO- include 4,4'-dihydroxydiphenylketones.

An example of bisphenols in which L is −CR ₁ R ₂₋ and R ₁ and R ₂ bind to each other to form an aliphatic ring is 1,1-bis (4-hydroxyphenyl) cyclohexane (BPZ). , And bisphenols having a cyclohexane skeleton such as 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane (BPTMC).

Examples of bisphenols in which L is −CR ₁ R ₂ − and R ₁ and R ₂ are bonded to each other to form an aromatic ring are 9,9 − bis (3-methyl-4-hydroxyphenyl). Includes bisphenols having a fluorene skeleton such as fluorene (BCF), 9,9-bis (3,5-dimethyl-4-hydroxyphenyl) fluorene (BXF).

The aromatic dialcohol component constituting the polyarylate may be one kind or two or more kinds.

Among these, from the viewpoint of increasing the solubility of the resin in the solvent and improving the adhesion of the film to the metal, for example, a sulfur atom (-S-, -SO- or -SO _2- ) is added to the main chain. The contained bisphenols are preferable. From the viewpoint of increasing the heat resistance of the film, for example, bisphenols containing a sulfur atom in the main chain and bisphenols having a cycloalkylene skeleton are preferable. Bisphenols having a fluorene skeleton are preferable from the viewpoint of reducing birefringence of the film and increasing wear resistance.

Bisphenols having a cyclohexane skeleton and bisphenols having a fluorene skeleton are preferably used in combination with bisphenols containing an isopropanol group. In that case, the content ratio of the bisphenols having a cyclohexane skeleton or the bisphenols having a fluorene skeleton to the bisphenols containing an isopropylidene group is 10/90 to 90/10 (molar ratio), preferably 20/80 to 20/80. It can be 80/20 (molar ratio).

The polyarylate may further contain an aromatic polyhydric alcohol component unit other than the aromatic dialcohol component as long as the effect of the present embodiment is not impaired. Examples of aromatic polyhydric alcohol components include the compounds described in paragraph [0015] of Japanese Patent No. 4551503. Specifically, Tris (4-hydroxyphenyl) methane, 4,4'-[1- [4- [1- (4-hydroxyphenyl) -1- (4-methylethyl] phenyl] ethylidene] bisphenol, 2,3. Includes 4,4'-tetrahydroxybenzophenone, 4- [bis (4-hydroxyphenyl) methyl] -2-methoxyphenol, tris (3-methyl-4-hydroxyphenyl) methane and the like. The content ratio of these aromatic polyhydric alcohol component units can be appropriately set according to the required characteristics, and is, for example, 5 with respect to the total of the aromatic dialcohol component units and the other aromatic polyhydric alcohol component units. It can be less than or equal to mol%.

(Aromatic dicarboxylic acid component unit)
The aromatic dicarboxylic acid constituting the aromatic dicarboxylic acid component unit can be terephthalic acid, isophthalic acid or a mixture thereof.

A mixture of terephthalic acid and isophthalic acid is preferable from the viewpoint of enhancing the mechanical properties of the film. The content ratio of terephthalic acid and isophthalic acid is preferably terephthalic acid / isophthalic acid = 90/10 to 10/90 (molar ratio), more preferably 70/30 to 30/70, and further preferably 50/50. When the content ratio of terephthalic acid is in the above range, a polyarylate having a sufficient degree of polymerization can be easily obtained, and a film having sufficient mechanical properties can be easily obtained.

The polyarylate may further contain an aromatic dicarboxylic acid component unit other than terephthalic acid and isophthalic acid as long as the effect of the present embodiment is not impaired. Examples of such aromatic dicarboxylic acid components are orthophthalic acid, 2,6-naphthalenedicarboxylic acid, diphenylic acid, 4,4'-dicarboxydiphenyl ether, bis (p-carboxyphenyl) alkane, 4,4'-. Dicarboxyphenyl sulfone and the like are included. The content ratio of the aromatic dicarboxylic acid component unit other than terephthalic acid and isophthalic acid can be appropriately set according to the required characteristics, but is the total of the terephthalic acid component, the isophthalic acid component unit and the other aromatic dicarboxylic acid component units. For example, it can be 5 mol% or less.

(Glass-transition temperature)
The glass transition temperature of the polyarylate is preferably 260 ° C. or higher and 350 ° C. or lower, more preferably 265 ° C. or higher and lower than 300 ° C., and further preferably 270 ° C. or higher and lower than 300 ° C.

The glass transition temperature of polyarylate can be measured according to JIS K7121 (1987). Specifically, using a DSC6220 manufactured by Seiko Instruments Co., Ltd. as a measuring device, measurement can be performed under the conditions of a polyarylate sample of 10 mg and a heating rate of 20 ° C./min.

The glass transition temperature of the polyarylate can be adjusted by the type of aromatic dialcohol component constituting the polyarylate and the like. In order to raise the glass transition temperature, for example, it is preferable to include "a unit derived from bisphenols containing a sulfur atom in the main chain" as an aromatic dialcohol component unit.

(Intrinsic viscosity)
The intrinsic viscosity of the polyarylate is preferably 0.3 to 1.0 dl / g, more preferably 0.4 to 0.9 dl / g, still more preferably 0.45 to 0.8 dl / g, and 0. It is more preferably 5 to 0.7 dl / g. When the intrinsic viscosity of polyarylate is 0.3 dl / g or more, the molecular weight of the resin composition tends to be constant or higher, and a film having sufficient mechanical properties and heat resistance can be easily obtained. When the intrinsic viscosity of polyarylate is 1.0 dl / g or less, it is possible to suppress the excessive increase in the viscosity of the solution during film formation.

Intrinsic viscosity can be measured according to ISO 1628-1. Specifically, a solution prepared by dissolving a polyarylate sample in 1,1,2,2-tetrachloroethane so as to have a concentration of 1 g / dl is prepared. The intrinsic viscosity of this solution at 25 ° C. is measured using an Ubbelohde viscous tube.

The method for producing the polyarylate may be a known method, preferably an interface in which an aromatic dicarboxylic acid halide dissolved in an organic solvent incompatible with water and an aromatic dialcohol dissolved in an alkaline aqueous solution are mixed. It may be a polymerization method (WM EARECKSON, J. Poly. Sci. XL399, 1959, Japanese Patent Publication No. 40-1959).

The content of the polyarylate may be 50% by mass or more, preferably 60% by mass or more, and more preferably 80% by mass or more with respect to the entire polyarylate film.

〔solvent〕
In the present embodiment, the solvent contained in the casting dope includes a good solvent and a poor solvent. As a good solvent, any solvent that dissolves a polyimide resin, a cycloolefin resin, and a polyarylate resin can be used without limitation.

For example, the chlorine-based organic solvent is dichloromethane (methylene chloride, methylene chloride), and the non-chlorine-based organic solvent is methyl acetate, ethyl acetate, amyl acetate, acetone, tetrahydrofuran (THF), 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, etc. can be mentioned. For example, dichloromethane, methyl acetate, ethyl acetate and acetone can be preferably used as the main solvent, and dichloromethane or ethyl acetate is particularly preferable.

As the poor solvent, a polyimide resin, a cycloolefin resin, or a polyarylate resin can be used without limitation as long as it swells alone or does not dissolve. For example, as the poor solvent, a linear or branched aliphatic alcohol having 1 to 4 carbon atoms can be used. Examples of the linear or branched aliphatic alcohol having 1 to 4 carbon atoms include methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol, and tert-butanol. Of these, methanol and ethanol are preferably used because of the stability of the dope, the relatively low boiling point, and the good drying property. Further, a poor solvent such as hexane, heptane, benzene, toluene, xylene, chlorobenzene and o-dichlorobenzene may be used in combination.

When a polyimide resin, a cycloolefin resin, a polyarylate resin, or the like is contained in the dope as in the present embodiment, if the ratio of the poor solvent to the mixed solvent in the dope increases, the cast film gels and is supported. Adhesion to the body (peeling force) decreases, and peeling becomes unstable. Therefore, the ratio of the poor solvent to the mixed solvent is preferably 16% by mass or less, and more preferably 10% by mass or less. The ratio (% or mass%) of the poor solvent to the mixed solvent is defined by the following formula.
Poor solvent ratio = {b / (a + b)} × 100
here,
a: Mass of good solvent in mixed solvent (g)
b: Mass (g) of the poor solvent in the mixed solvent
Is.

〔Additive〕
In the production of the optical film of the present embodiment, as additives to be contained in the dope, fine particles, a plasticizer, an ultraviolet absorber, an antioxidant, a sugar ester compound, a phase difference adjuster, a light stabilizer, an antistatic agent, and a release agent. , Thickener and the like may be used. Hereinafter, only the main additives will be described.

<Fine particles (matting agent)>
It is desirable that the optical film of the present embodiment contains a matting agent in order to impart irregularities on the film surface during film formation, ensure slipperiness, and achieve a stable winding shape. By containing the matting agent, it is possible to prevent the produced optical film from being scratched or deteriorated in transportability when it is handled.

Examples of the matting agent include fine particles of an inorganic compound and fine particles of a resin. Examples of fine particles of inorganic compounds are silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, silicic acid. Examples thereof include magnesium and calcium phosphate. The fine particles containing silicon are preferable in that the turbidity is low, and silicon dioxide is particularly preferable.

The average particle size of the primary particles of the fine particles is preferably in the range of 5 to 400 nm, more preferably in the range of 10 to 300 nm. These may be mainly contained as secondary aggregates having a particle size in the range of 0.05 to 0.3 μm, and particles having an average particle size in the range of 80 to 400 nm are primary particles without agglutination. It is also preferable that it is contained as.

The content of these fine particles in the optical film is preferably in the range of 0.01 to 3.0% by mass, and particularly preferably in the range of 0.01 to 2.0% by mass.

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

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

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

Among these, Aerosil 200V, Aerosil R972V, and Aerosil R812 are particularly preferably used because they have a large effect of lowering the friction coefficient while keeping the haze of the optical film low.

<Plasticizer>
A polyester resin can be used as the plasticizer to be added to the optical film. The polyester resin is obtained by polymerizing a dicarboxylic acid and a diol, and 70% or more of the dicarboxylic acid constituent unit (constituent unit derived from the dicarboxylic acid) is derived from the aromatic dicarboxylic acid and the diol constituent unit (derived from the diol). More than 70% of the constituent units) are derived from aliphatic diols.

The proportion of the constituent unit derived from the aromatic dicarboxylic acid is 70% or more, preferably 80% or more, and more preferably 90% or more. The proportion of the constituent units derived from the aliphatic diol is 70% or more, preferably 80% or more, and more preferably 90% or more. Two or more kinds of polyester resins may be used in combination.

Examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, naphthalenedicarboxylic acid such as 2,7-naphthalenedicarboxylic acid, 4,4'-biphenyldicarboxylic acid, and the like. Examples thereof include 3,4'-biphenyldicarboxylic acid and the like and ester-forming derivatives thereof.

As the polyester resin, aliphatic dicarboxylic acids such as adipic acid, azelaic acid and sebacic acid and monocarboxylic acids such as benzoic acid, propionic acid and butyric acid can be used as long as the object of the present invention is not impaired.

Examples of the aliphatic diol include ethylene glycol, 1,3-propylene diol, 1,4-butanediol, 1,4-cyclohexanedimethanol, 1,6-hexanediol and the like, and ester-forming derivatives thereof.

As the polyester resin, monoalcohols such as butyl alcohol, hexyl alcohol, and octyl alcohol, and polyhydric alcohols such as trimethylolpropane, glycerin, and pentaerythritol can be used as long as the object of the present embodiment is not impaired. ..

A known method such as a direct esterification method or a transesterification method can be applied to the production of the polyester resin. Examples of the polycondensation catalyst used in the production of the polyester resin include known antimony trioxide, antimony pentoxide and other antimony compounds, germanium oxide and other germanium compounds, titanium acetate and other titanium compounds, and aluminum chloride and other aluminum compounds. Yes, but not limited to these.

Preferred polyester resins include polyethylene terephthalate resin, polyethylene terephthalate-isophthalate copolymer resin, polyethylene-1,4-cyclohexanedimethylene-terephthalate copolymer resin, polyethylene-2,6-naphthalenedicarbochelate resin, polyethylene-2, 6-Naphthalenedicarboxylate-terephthalate copolymer resin, polyethylene-terephthalate-4,4'-biphenyldicarboxylate resin, poly-1,3-propylene-terephthalate resin, polybutylene terephthalate resin, polybutylene-2,6-naphthalene There are dicarboxylate resins and the like.

More preferable polyester resins include polyethylene terephthalate resin, polyethylene terephthalate-isophthalate copolymer resin, polyethylene-1,4-cyclohexanedimethylene-terephthalate copolymer resin, polybutylene terephthalate resin and polyethylene-2,6-naphthalenedicarboxylate. Resin is mentioned.

The intrinsic viscosity of the polyester resin (phenol / 1,1,2,2-tetrachloroethane = 60/40 mass ratio measured at 25 ° C. in a mixed solvent) is in the range of ^{0.7 to 2.0 cm 3 / g.} Is preferable, and more preferably, it is in the range of ^{0.8 to 1.5 cm 3 / g.} When the intrinsic viscosity is 0.7 cm ³ / g or more, the molecular weight of the polyester resin is sufficiently high, so that the molded product made of the polyester resin composition obtained by using the intrinsic viscosity has the necessary mechanical properties as the molded product. And the transparency is good. When the intrinsic viscosity is 2.0 cm ³ / g or less, the moldability is good. As the other plasticizer, the compounds described in the general formulas (PEI) and the general formula (PEII) of paragraphs [0056] to [0080] of JP2013-97279A may be used.

〔Example〕
Hereinafter, specific examples of the present invention will be described, but the present invention is not limited to these examples.

<Manufacturing of optical film 1>
(Synthesis of polyimideA)
2,2-Bis (3,4-dicarboxyphenyl) -1,1,1, in a four-necked flask equipped with a dry nitrogen gas introduction tube, a cooler, a Dean-Stark aggregator filled with toluene, and a stirrer. 25.59 g (57.6 mmol) of 3,3,3-hexafluoropropane dianhydride was added to N, N-dimethylacetamide (134 g), and the mixture was stirred at room temperature under a nitrogen stream. To it, 19.2 g (60 mmol) of 4,4'-diamino-2,2'-bis (trifluoromethyl) biphenyl was added, and the mixture was heated and stirred at 80 ° C. for 6 hours. Then, the outside temperature was heated to 190 ° C., and the water generated by imidization was azeotropically distilled off together with toluene. After continuing heating, refluxing and stirring for 6 hours, no water was observed. Subsequently, the mixture was heated for 7 hours while distilling off toluene, and after distilling off toluene, methanol was added and reprecipitated to obtain polyimide A represented by the following formula.

(Preparation of doping)
A main dope having the following composition was prepared. First, tetrahydrofuran (THF) and ethanol (EtOH) were added as mixed solvents to the pressure dissolution tank. The content of THF in the mixed solvent was 99% by mass. The polyimide A prepared above was put into the pressurized dissolution tank containing the mixed solvent with stirring. This was heated and completely dissolved while stirring, and this was dissolved in Azumi Filter Paper No. 1 manufactured by Azumi Filter Paper Co., Ltd. After filtering using 244, the remaining components were added and stirred to dissolve to prepare the main dope.

<Composition of main dope>
Polyimide A 250.0 parts by mass Tetrahydrofuran 720 parts by mass Ethanol 80 parts by mass Fine particles: Nippon Aerodil Co., Ltd. R812 (primary particle size 7 nm)
2.63 parts by mass

(Hypersalivation process)
Then, using an endless belt spreading device, the dope was uniformly cast on the stainless belt support at a temperature of 30 ° C. and a width of 1500 mm. Then, the temperature of the stainless steel belt was controlled to 30 ° C., and the solvent was evaporated on the stainless steel belt support until the residual solvent amount became 75% to form a cast film on the support. At this time, the moving speed V ₂ of the stainless steel belt support and 8m / min, the discharge speed V _1E of the dope from the casting width end portion of the casting die and 10 m / min, the dope from the casting width central portion The discharge speed V _1C was set to 12 m / min. Regarding the dope discharge rates V _1E and V _1C , the slit gap of the casting die is changed in the casting width direction (more specifically, the slit gap is spread wider than the central portion of the casting width). Adjusted (by spreading at the edges).

Here, the specific values of the dope discharge rates V _1E and V _1C can be obtained by the following method. First, as shown in FIG. 8, the film thickness D1 (μm) of the dope in the portion 1 mm or less in the ejection direction of the dope from the casting die 2 is measured by the film thickness meter 60a (for example, the spectroscopic interference laser displacement meter SI manufactured by KEYENCE CORPORATION). -Measure by F80). Then, the film thickness D2 (μm) of the dope in the portion within 1 mm after the dope lands on the support 3 is measured by a film thickness meter 60b (for example, a spectroscopic interference laser displacement meter SI-F80 manufactured by KEYENCE CORPORATION). The effect of film thickness reduction due to drying can be ignored.

When the moving speed of the support 3 is V2 (m / min) and the ejection speed of the dope is V1 (m / min), the film thickness ratio D1 / D2 has the same relationship as the draw ratio V2 / V1. Since the moving speed V2 of the support 3 is known in advance, the discharge speed V1 can be obtained from V1 = (D2 / D1) × V2. Therefore, by measuring the film thickness of the dope discharged from the end of the casting width 2 and the film thickness of the dope discharged from the center of the casting width, and substituting into the above equation, the dope Discharge speeds V _1E and V _1C can be obtained.

(Peeling process)
Then, the cast film was peeled off from the stainless belt support at a peeling tension of 180 N / m. The amount of residual solvent at that time was 22% by mass.

(Drying process)
The peeled cast film was dried at a drying temperature at which the residual solvent amount was less than 0.1% by mass under a transport tension of 100 N / m and a drying time of 15 minutes to obtain a film having a dry film thickness of 25 μm. Then, the obtained film was wound up and heat-treated at 300 ° C. for 5 minutes with an infrared heater to obtain an optical film 1 which is a polyimide film having a width of 1500 mm.

<Manufacturing of optical films 2 to 18>
In the casting process, the moving speed V _{2 of the stainless belt support, the dope ejection speed V 1E} from the casting width end from the casting die, and the dope ejection speed V _1C from the casting width center are shown. Optical films 2 to 18 were produced in the same manner as in the production of optical film 1, except that the changes were made as in 1. _{In the film formation of the optical films 2 to 18, the dope ejection speed V 1E} and the ejection speed V _1C are changed by changing the gap of the slit of the casting die in which the dope is discharged in the casting width direction. I let you. _{That is, V 1E} <V _1C is realized by widening the slit gap of the flow die at the end of the flow width rather than the center of the flow width, and the slit gap is narrowed at the end of the flow width rather than the center of the flow width. As a result, V _1E > V _1C was realized.

<Manufacturing of optical film 19>
The optical film 19 was produced in the same manner as the optical film 1 except that the resin contained in the dope was changed to a polyarylate resin and the film forming conditions were slightly changed. Hereinafter, a method for producing the polyarylate resin and film forming conditions different from those of the optical film 1 will be described.

(Making polyarylate resin)
After adding 2514 parts by weight of water to the reaction vessel, 22.7 parts by weight of sodium hydroxide and 9,9-bis (3,5-dimethyl-4-hydroxyphenyl) fluorene (BCF) as an aromatic dialcohol component. 35.6 parts by weight, 2,2-bis (3,5-dimethyl-4-hydroxyphenyl) propane (TMBPA) 18.5 parts by weight, p-tert-butylphenol (PTBP) 0.049 parts by weight as a molecular weight modifier Was dissolved, 0.34 parts by weight of a polymerization catalyst (tributylbenzylammonium chloride) was added, and the mixture was stirred.

On the other hand, 26.8 parts by weight of an equal amount mixture of terephthalic acid chloride and isophthalic acid chloride as an aromatic dicarboxylic acid component was weighed and dissolved in 945 parts by weight of methylene chloride. This methylene chloride solution was added to the alkaline aqueous solution prepared above under stirring to initiate polymerization. The polymerization reaction temperature was adjusted to be 15 ° C. or higher and 20 ° C. or lower. The polymerization was carried out for 2 hours, and then acetic acid was added into the system to stop the polymerization reaction, and the organic phase and the aqueous phase were separated.

The obtained organic phase was washed with twice the amount of ion-exchanged water as the organic phase in each washing, and then the operation of separating into the organic phase and the aqueous phase was repeated. Washing was completed when the electrical conductivity of the wash water became less than 50 μS / cm. The washed organic phase was put into a warm water tank equipped with a homomixer at 50 ° C. to evaporate methylene chloride to obtain a powdery polymer. Further dehydration and drying were carried out to obtain a polyarylate resin.

(Film formation of optical film)
The dope containing the polyarylate resin was uniformly cast from the casting die onto the stainless steel belt of the belt casting device. A stainless steel belt having a length of 20 m was used. At this time, the moving speed V ₂ of the stainless steel belt support to a 25 m / min, to control the slit gap of the casting die in the casting width direction, the discharge speed of the dope from the casting width end portion of the casting die V _1E was set to 30 m / min, and the dope discharge rate V _1C from the central portion of the flow width was set to 35 m / min. Then, the surface temperature of the stainless steel belt is set to 35 ° C., and the casting film is blown with a wind of 35 ° C. to evaporate the solvent until the residual solvent amount becomes 38%, and then the film is peeled off from the stainless steel belt and the casting film is formed. Got

The obtained cast film was stretched 1.2 times at 170 ° C. in the MD direction by utilizing the difference in peripheral speed between the rolls, and then stretched 1.2 times at 230 ° C. in the TD direction with a tenter.

The stretched film (film) after stretching was dried for 30 minutes while being conveyed in a drying device at 125 ° C. with a large number of rolls, and then nerling with a width of 15 mm and a height of 10 μm was applied to both ends of the film in the width direction. As a polyarylate film, an optical film 19 having a film thickness of 40 μm and a width of 1500 mm was obtained.

<Manufacturing of optical films 20 to 24>
In the casting process, the moving speed V _{2 of the stainless belt support, the dope ejection speed V 1E} from the casting width end from the casting die, and the dope ejection speed V _1C from the casting width center are shown. Optical films 20 to 24 were produced in the same manner as in the production of the optical film 19, except that the changes were made as in 1. The dope discharge rates V _1E and V _1C were adjusted by controlling the slit gap of the casting die in the casting width direction.

<Manufacturing of optical film 25>
The optical film 25 was produced in the same manner as the optical film 1 except that the resin contained in the dope was changed to a cycloolefin resin and the film forming conditions were slightly changed. Hereinafter, a method for producing a cycloolefin resin and film forming conditions different from those of the optical film 1 will be described.

(Preparation of cycloolefin resin)
8-Methoxycarbonyl-8-methyltetracyclo [4.4.0.12,5.17,10] -3-dodecene represented by the following structural formula, 50 g of dodecene, 2.3 g of molecular weight regulator 1-hexene and 100 g of toluene was placed in a reaction vessel substituted with nitrogen and heated to 80 ° C. To this, 0.09 ml of a toluene solution of triethylaluminum (0.6 mol / L) and _{0.29 ml of a toluene solution of methanol-modified WCl 6} (0.025 mol / L) were added, and the mixture was reacted at 80 ° C. for 3 hours to make it heavy. I got a coalescence. Then, the obtained ring-opening copolymer solution was put into an autoclave, and 100 g of toluene was further added. Add 2500 ppm of RuHCl (CO) [P (C ₆ H ₅ )] ₃ which is a hydrogenation catalyst to the amount of monomer charged, set the hydrogen gas pressure to 9 to 10 MPa, and react at 160 to 165 ° C for 3 hours. gone. After completion of the reaction, a hydrogenated product was obtained by precipitating in a large amount of methanol solution. The cycloolefin resin which is a hydrogenated additive of the obtained ring-opening polymer has a glass transition temperature (Tg) = 167 ° C., a weight average molecular weight (Mw) = 13.5 × 10 ⁴ , and a molecular weight distribution (Mw / Mn) =. It was 3.06.

(Film formation of optical film)
A dope containing a cycloolefin resin was cast from a casting die onto a stainless band support at a temperature of 22 ° C. and a width of 2 m using a belt casting device. At this time, the moving speed V ₂ of the stainless steel belt support to a 25 m / min, to control the slit gap of the casting die in the casting width direction, the discharge speed of the dope from the casting width end portion of the casting die V _1E was set to 30 m / min, and the dope discharge rate V _1C from the central portion of the flow width was set to 35 m / min. Then, the solvent was evaporated on the stainless band support until the residual solvent amount reached 30%, and the obtained casting film was peeled from the stainless band support at a peeling tension of 162 N / m.

Next, the peeled cast film was dried at a drying temperature of 160 ° C. while evaporating the solvent at 35 ° C. and stretching it 1.25 times in the width direction (TD direction) by tenter stretching. The amount of residual solvent when stretching by zone stretching was started was 10.0%, and the amount of residual solvent when stretching by tenter was started was 5.0%.

After stretching with a tenter, a relaxation treatment was performed at 160 ° C. for 5 minutes, and then drying was completed while transporting the drying zone at 120 ° C. with a large number of rollers. The obtained film was slit to a width of 1.5 m, both ends of the film were knurled with a width of 10 mm and a height of 5 μm, and then wound around a core to obtain an optical film 25 as a cycloolefin film. The film thickness of the optical film 25 was 40 μm, the winding length was 4000 m, and the width was 1500 mm.

<Manufacturing of optical films 26 to 30>
In the casting process, the moving speed V _{2 of the stainless belt support, the dope ejection speed V 1E} from the casting width end from the casting die, and the dope ejection speed V _1C from the casting width center are shown. Optical films 26 to 30 were produced in the same manner as in the production of the optical film 25, except that the changes were made as in 1. The dope discharge rates V _1E and V _1C were adjusted by controlling the slit gap of the casting die in the casting width direction.

<Evaluation>
(Evaluation of phase difference unevenness)
The peeling step is performed under the same film-forming conditions as when each optical film was manufactured as described above. The central part (here, the area including the center of the width and having a width of 10% of the total width) and the end part (here, the area including the edge of the width and having a width of 10% of the total width) are cut out and automatically cut out. A birefringence index was obtained by measuring the three-dimensional refractive index at a wavelength of 590 nm in an environment of 23 ° C. and 55% RH (relative humidity) using an Axoscan Mueller Matrix Polarimeter (manufactured by Axometrics). By substituting the average refractive indexes nx, ny, and nz into the following equations (i) and (ii), the in-plane retardation Ro and the thickness direction retardation Rth were obtained.
Equation (i): Ro = (nx-ny) × d (nm)
Equation (ii): Rth = {(nx + ny) /2-nz} × d (nm)
[In the formula (i) and the formula (ii), nx represents the refractive index in the direction x in which the refractive index is maximized in the in-plane direction of the film. ny represents the refractive index in the in-plane direction of the film in the direction y orthogonal to the direction x. nz represents the refractive index in the thickness direction z of the film. d represents the thickness (nm) of the film. ]

Then, the difference ΔRth (= Rth1-Rth2) of the retardation is obtained from the retardation Rth1 in the thickness direction of the central portion of the cast film and the retardation Rth2 in the thickness direction of the end portion of the cast film, and the following evaluation criteria are obtained. The phase difference unevenness was evaluated based on the above, and this was used as the evaluation for each optical film 1 to 30.
"Evaluation criteria"
⊚ ... ΔRth is less than 1 nm, and there is no phase difference unevenness.
◯ ... ΔRth is 1 nm or more and less than 3 nm, and there is almost no phase difference unevenness.
ΔRth is 3 nm or more and less than 5 nm, and there is some phase difference unevenness, but there is no problem.
X ... ΔRth is 5 nm or more, and there is considerable phase difference unevenness.

(Evaluation of horizontal unevenness)
A film was formed by the above-mentioned manufacturing method, and each wound optical film was unwound by a predetermined length and visually observed, and horizontal unevenness (film thickness unevenness) was evaluated based on the following criteria. Since the horizontal unevenness once occurred during casting, it does not disappear even if the film forming conditions are changed. Therefore, as described above, the horizontal unevenness was evaluated by visually observing the wound film after the film formation.
"Evaluation criteria"
◎ ・ ・ ・ No horizontal unevenness is observed, and it can be used as an optical film without any problem.
◯ ・ ・ ・ There is partial horizontal unevenness, but by stacking easy-adhesive layers and hard coats, the applicable applications are not limited, and it can be used as an optical film without problems.
Δ: There is partial horizontal unevenness, but by stacking easy-adhesive layers and hard coats, the applicable applications are limited, but it is a level that can be used as an optical film.
×: There is a lot of horizontal unevenness visually, and it is a level that cannot be used as an optical film.

The evaluation results for each optical film 1 to 30 are shown in Table 1. In Table 1, PI is a polyimide resin, PAR is a polyarylate resin, and COP is a cycloolefin resin. Table 1 also shows the correspondence between each optical film and the examples or comparative examples. It should be noted that Examples 1, 5, 12, and 13 are merely reference examples of the present invention and do not belong to the scope of the present invention.

From Table 1, in Comparative Examples 1 to 13, in the film formation of the optical film using any of the polyimide resin, the cycloolefin resin, and the polyarylate resin, both the evaluation of the phase difference unevenness and the horizontal stage unevenness were poor (×). It has become. It is considered that this is because in Comparative Examples 1 to 13, at least one of the following conditional expressions (1) and (2) is not satisfied in the casting step.
(1) V ₂ > V _1C
(2) (V ₂ / V _1E )> (V ₂ / V _1C )

That is, since both the conditional expressions (1) and (2) are not satisfied, the strength of the end portion in the width direction of the casting film cannot be increased by stretching in the casting direction. As a result, when the cast film is peeled from the support, the end portion flutters and peeling unevenness occurs, and the peeling tension is not evenly applied in the width direction of the casting film, so that it is considered that the phase difference unevenness occurs. Be done. Further, since the conditional expression (2) is not satisfied, the dope discharged from the end of the casting width of the casting die is not stable, and the entire dope tends to vibrate due to disturbance such as vibration of the support, resulting in the result. It is probable that horizontal unevenness occurred.

On the other hand, in Examples 1 to 17, both of the above conditional formulas (1) and (2) are satisfied in the film formation of the optical film using any of the polyimide resin, the cycloolefin resin, and the polyarylate resin. is doing. In the casting process, the dope discharged from the casting width end of the casting die is stretched in the casting direction, and the strength of the widthwise end of the casting film increases, so that when peeling from the support, The edges of the flow film are less likely to flutter, reducing uneven peeling. As a result, the peeling tension is evenly applied in the width direction of the flow film, the orientation direction of the molecules is less likely to vary between the end and center of the flow film, and the phase difference unevenness is reduced. it is conceivable that. Further, by satisfying the conditional expression (2), the dope discharged from the end of the casting width of the casting die is stable and less likely to shake, so that the entire dope can be suppressed from shaking due to disturbance. It is considered that the horizontal unevenness was reduced by this.

In particular, from the results of Examples 1 to 5, 14 and 16, it can be said that it is desirable to further satisfy the following conditional expression (3) in that the phase difference unevenness and the horizontal step unevenness can be further reduced. That is,
(3) 3 <(V ₂ / V _1C ) ≤ 10
Is.

Further, from the results of Comparative Example 3, Examples 6 to 11 and 14 to 17, satisfying the following conditional expression (4) further reduces phase difference unevenness and horizontal step unevenness in a well-balanced manner. It can be said that it is desirable. That is,
(4) 1.05 ≦ (V ₂ / V _1E ) / (V ₂ / V _1C ) ≦ 1.5
Is.

Above all, from the results of Examples 3, 7, 14 to 17, satisfying the following conditional expressions (3') and (4') ensures that both phase difference unevenness and horizontal step unevenness are reduced. It can be said that it is even more desirable in that it can be done. That is,
(3') 4.6 ≤ (V ₂ / V _1C ) ≤ 5.0
(4') 1.2 ≤ (V ₂ / V _1E ) / (V ₂ / V _1C ) ≤ 1.3
Is.

〔supplement〕
Although the embodiments of the present invention have been described above, the scope of the present invention is not limited to this, and various modifications can be made without departing from the gist of the invention.

The method for manufacturing the optical film of the present embodiment described above can be expressed as follows.

1. 1. It is a method of manufacturing an optical film by a solution casting film forming method.
A dope containing any of a polyimide resin, a cycloolefin resin, and a polyarylate resin and a solvent is discharged from a casting die, cast on a moving support, and the cast dope is dried and poured. The casting process to form a film and
Including a peeling step of peeling the cast film from the support.
The dope ejection speed from the end of the casting width of the casting die is V _1E (m / min), and the ejection speed of the dope from the center of the casting width of the casting die is V _1C (m / min). When the moving speed of the support is V ₂ (m / min), the method for producing an optical film is characterized by simultaneously satisfying the following conditional equations (1) and (2);
(1) V ₂ > V _1C
(2) (V ₂ / V _1E )> (V ₂ / V _1C )
Is.

2. 2. The method for producing an optical film according to 1 above, which further satisfies the following conditional expression (3);
(3) 3 <(V ₂ / V _1C ) ≤ 10
Is.

3. 3. The method for producing an optical film according to 2 above, which further satisfies the following conditional expression (4);
(4) 1.05 ≦ (V ₂ / V _1E ) / (V ₂ / V _1C ) ≦ 1.5
Is.

4. The method for producing an optical film according to any one of 1 to 3 above, which further satisfies the following conditional formulas (3') and (4');
(3') 4.6 ≤ (V ₂ / V _1C ) ≤ 5.0
(4') 1.2 ≤ (V ₂ / V _1E ) / (V ₂ / V _1C ) ≤ 1.3
Is.

5. Of the casting die, by changing the gap of the slit where the dope is ejected in the casting width direction, from the 1, characterized by slower than the discharge velocity V _1C discharge rate V _1E of the dope 4. The method for manufacturing an optical film according to any one of 4.

INDUSTRIAL APPLICABILITY The present invention can be used for producing an optical film containing any of a polyimide resin, a cycloolefin resin, and a polyarylate resin by a solution casting film forming method.

2 Dispersion die 2a Dispersion width center 2b Dispersion width end 3 Support 5 Dispersion film 31 Slit

Claims (3)

It is a method of manufacturing an optical film by a solution casting film forming method.
A dope containing any of a polyimide resin, a cycloolefin resin, and a polyarylate resin and a solvent is discharged from a casting die, cast on a moving support, and the cast dope is dried and poured. The casting process to form a film and
Including a peeling step of peeling the cast film from the support.
In the casting die, the region for discharging the dope forming the end portion in the width direction including the edge of the casting film (the width is 10% or less of the total width of the casting film) on the support is described. As the end of the flow width of the flow die,
In the casting die, the region for discharging the dope forming the central portion (the width is 10% or less of the total width of the casting film) including the center in the width direction of the casting die is the flow of the casting die. The central part of the total width
The dope ejection speed from the end of the casting width of the casting die is V _1E (m / min), and the ejection speed of the dope from the center of the casting width of the casting die is V _1C (m / min). When the moving speed of the support is V ₂ (m / min), an optical film manufacturing method that simultaneously satisfies the following conditional equations (1), (2) and (3);
(1) V ₂ > V _1C
(2) (V ₂ / V _1E )> (V ₂ / V _1C )
(3) 3 <(V ₂ / V _1C ) ≤ 10
Is. The method for producing an optical film according to claim 1, further satisfying the following conditional expression (4);
(4) 1.05 ≦ (V) ₂ / V _1E ) / (V ₂ / V _1C ) ≤ 1.5
Is. The method for producing an optical film according to claim 1 or 2, further satisfying the following conditional formulas (3') and (4');
(3') 4.6 ≤ (V) ₂ / V _1C ) ≤ 5.0
(4') 1.2 ≤ (V) ₂ / V _1E ) / (V ₂ / V _1C ) ≤ 1.3
Is.

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