JP2003131006A - Optical film and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical film not only whose residual phase difference is small but also whose dispersion of optical axis is little and which is made of a noncrystalline thermoplastic resin, and manufacturing method therefor. SOLUTION: This is an optical film extrusion-molded by using a noncrystalline thermoplastic resin. When an optical film whose thickness is less than 100 μm whose residual phase difference is 10 nm or less, and whose dispersion of optical axis is ±10 deg. or lower, and a film which is extruded in a sheet shape from a die installed at an extruding machine made of the noncrystalline thermoplastic resin, are adhered to a cooling roll. (1) When the glass transition temperature of the resin is given as Tg, the film temperature immediately before the point of contact with the cooling roll is Tg+50 deg.C or higher, or (2) when the thickness immediately after the film is adhered to the cooling roll is given as A, the lip clearance of the die is given as B, B/A is to be within the prescribed range according to the thickness of the film, and the temperature of the film immediately before the point of contact with the cooling roll is Tg+30 deg.C or higher.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical film used for optical applications and display fields, and a method for producing the same, and more specifically, an optical film obtained by extrusion molding and having a small optical distortion (birefringence) and the same. It relates to a manufacturing method.

[0002]

2. Description of the Related Art In recent years, a film having excellent transparency and a small residual retardation has been required for optical applications and displays. However, when a film is manufactured by melt extrusion, there is a problem that stress distortion occurs due to deformation during film formation, and optical distortion remains.

Since this optical distortion remains in the film as a phase difference, it becomes a serious problem when the film is used for a substrate of an optical disk or a liquid crystal display.

As a means for reducing this optical distortion, for example,
For example, Japanese Patent Laid-Open No. 4-275129 discloses a polycarbonate.
Resin, using a resin temperature of 300 to 330 ° C.
Lass transition temperature (Tg) + 150 ° C to Tg + 180 ° C
The air gap is 80 to 100 mm and the
Extrusion is performed with the temperature of the waste roll set to 100 to 140 ° C.
A method of making an optical film is disclosed. here,
The shear strain during extrusion and the cooling shrinkage force of the film are
Lance, which results in an optical distortion of 5 × 10 ^-Fivebelow
It is said that an optical film can be obtained.

Further, in Japanese Patent Laid-Open No. 2000-280268, as a method for producing a sheet having a thickness of 0.1 to 2 mm and a residual phase difference of 10 nm or less, when the glass transition temperature of the resin constituting the sheet is Tg, A method for producing an optical film is disclosed in which the temperature of the extrusion belt and the roll is Tg to Tg + 50 ° C. and the extrusion molding is performed.

However, in the manufacturing method described in Japanese Patent Laid-Open No. 4-275129, when a resin other than polycarbonate, such as a norbornene-based resin, is used,
Since the resin temperature becomes too high, the film may be deteriorated.

Further, according to the manufacturing method described in Japanese Patent Laid-Open No. 2000-280268, it was not possible to obtain a thin optical film having a thickness of less than 100 μm. Further, when the film is peeled off from the belt, there is a concern that the film may be stretched and optical distortion may remain. The residual optical strain in the film causes a phase difference when light passes through the film, and is not suitable for optical applications and display fields.

The phenomenon that the retardation (optical strain) remains in the film occurs because the molecules in the film are oriented in one direction. The residual retardation occurs when the resin is deformed at a temperature of Tg or higher in proportion to the magnitude of stress at the time of deformation. Since the stress at the time of deformation depends on the temperature of the resin and the amount of deformation, when the amount of deformation is the same, the stress changes depending on the temperature of the resin.

When a film is obtained by an extrusion molding method, usually, the resin extruded from a die is drawn down to a target film thickness in an air gap.
At this time, the resin temperature decreases. When the resin temperature drops,
The lower the temperature is, the larger stress is generated during the deformation, and the large phase difference based on the stress remains.

Further, in optical films used for optical applications and display fields, not only the residual phase difference indicating the magnitude of optical distortion but also the optical axis that is the direction of optical distortion is a problem. .

Conventionally, in order to stabilize the contact point between the cooling roll and the resin and suppress the occurrence of optical axis deviation, a method of pressing a film such as an air chamber, a touch roll, and full-face pinning to the cooling roll is generally used. Is used for. However, when these methods were used, more stress was likely to remain on the film at the contact, leaving more retardation.

Further, although amorphous thermoplastic resins are mainly used in optical applications, among them, saturated norbornene resins are excellent in heat resistance and transparency, have a small intrinsic birefringence and a small photoelastic coefficient. Has the advantage. Therefore, a film made of a saturated norbornene-based resin is suitable as an optical film, and therefore, in an optical film made of a saturated norbornene-based resin, it is strongly demanded to reduce the residual retardation and suppress the optical axis shift. There is.

[0013]

SUMMARY OF THE INVENTION In view of the above-mentioned state of the art, an object of the present invention is to provide an optical film made of an amorphous thermoplastic resin which has a small residual retardation and a small variation in the optical axis. And to provide a manufacturing method thereof.

[0014]

The optical film according to the first invention of the present application is an optical film extruded using an amorphous thermoplastic resin, has a thickness of less than 100 μm, and has a residual phase difference. Is 10 nm or less, and the optical axis deviation is ± 10 ° or less.

The optical film according to the second invention of the present application is an optical film extruded using an amorphous thermoplastic resin, having a thickness of less than 100 μm and a residual retardation of 3 nm or less. Yes, and the optical axis shift is ± 10 °
It is characterized by the following.

An optical film having a residual retardation of 10 nm or less, particularly an optical film having a residual retardation of 3 nm or less is suitable for optical applications such as optical discs and liquid crystal displays. In particular, in liquid crystal displays, for example, a raw film of a retardation plate or a protective film of a polarizing plate is required to have a particularly low retardation. Therefore, the optical film according to the present invention has a very small residual retardation, and is particularly effectively used for such applications.

The optical axis deviation of the optical film is ± 10 °.
In the following cases, since the directions of retardation are aligned, when the optical film according to the present invention is used for optical applications, the non-defective rate can be increased. Furthermore, the thickness of the optical film is 1
Since the thickness is less than 00 μm, it is possible to reduce the size of an optical disc, a liquid crystal display, or the like.

The optical film according to the third invention of the present application is
In the optical film according to the first or second invention of the present application, a norbornene-based resin described later is used as the amorphous thermoplastic resin. As a result, by utilizing the advantages of norbornene-based resin having excellent heat resistance and transparency, and having a small intrinsic birefringence and photoelastic coefficient, it is possible to provide an optical film having a smaller residual retardation and less variation in the optical axis. You can

The optical film according to the first or third invention of the present application is not particularly limited, but the fourth film described below is used.
Alternatively, it can be manufactured according to the manufacturing method of the sixth invention.

The optical film according to the first to third inventions of the present application is not particularly limited, but can be manufactured by the manufacturing method according to the fifth invention described below.

In the method for producing an optical film according to the fourth aspect of the present invention, assuming that the glass transition temperature of the amorphous thermoplastic resin is Tg, the amorphous thermoplastic resin extruded into a sheet form from a die attached to an extruder. When the resin film is brought into close contact with the cooling roll, the film temperature immediately before the contact between the cooling roll and the film is set to Tg + 50 ° C. or higher.

As shown in FIG. 1, by setting the film temperature immediately before the contact of the film extruded from the die with the cooling roll to Tg + 50 ° C. or more, even if the film is deformed in this state, stress strain in the resin Becomes smaller, and the residual retardation in the film can be 10 nm or less.

In the method for producing an optical film according to the fifth aspect of the invention, the glass transition temperature of the amorphous thermoplastic resin is set to T
When g is set, the film temperature immediately before the contact point between the cooling roll and the film is Tg + 80 ° C. or higher when the film extruded in a sheet shape from the die attached to the extruder is brought into close contact with the cooling roll.

As shown in FIG. 2, by setting the film temperature immediately before the contact of the film extruded from the die with the cooling roll to Tg + 80 ° C. or more, even if the film is deformed in this state, the stress in the resin is It becomes remarkably small, and it is possible to set the residual retardation in the film to 3 nm or less as well as 10 nm or less.

This is because the amorphous thermoplastic resin does not generate stress during deformation as the temperature of the resin becomes higher. Therefore, when the resin is deformed during film formation,
By performing appropriate temperature control, it is possible to reduce the stress strain of the resin that is generated, and it is possible to make it difficult for the residual phase difference to occur.

However, the film temperature immediately before the contact between the cooling roll and the film is Tg + 50 ° C. or higher or Tg.
Even if the temperature is controlled to + 80 ° C or higher, if the temperature varies in the width direction of the film, the stress due to the deformation of the resin will vary. Therefore, the residual phase difference may vary depending on the resin, and the stress applied to a specific part There is a possibility that the optical axis may be displaced due to concentration. Therefore, it is preferable that the temperature variation in the width direction of the film immediately before the contact between the cooling roll and the film is within 10 ° C.

The film temperature immediately before the contact between the cooling roll and the film is set to Tg + 50 ° C. or higher or Tg + 80 ° C.
As a specific method described above, for example, a method of controlling the temperature of the mold can be considered. In this case, if the mold temperature is raised excessively, some resins are thermally deteriorated, but by adopting a temperature condition that does not cause thermal deterioration, it is possible to reliably obtain an optical film that can satisfy the above-mentioned residual retardation.
In addition, the film temperature immediately before the contact is Tg + 50
A method of narrowing the air gap can be used in order to set the temperature to not less than 0 ° C or Tg + 80 ° C. In this case, the size of the air gap may be set in consideration of the thickness accuracy of the die line and the film.

On the other hand, a specific method for keeping the temperature variation in the width direction of the film within 10 ° C. immediately before the contact between the cooling roll and the film is not particularly limited, but, for example, the accuracy of the mold temperature is accurate. It is conceivable to raise the temperature, to maintain a uniform resin temperature in the width direction by using a heater whose output is variable in the width direction in the air gap, or to enclose the resin in a heat insulation box to prevent disturbance.

In the method for producing an optical film according to the sixth aspect of the invention, the thickness immediately after the film made of the amorphous thermoplastic resin extruded in a sheet shape from the die attached to the extruder is adhered to the cooling roll is adjusted. When A and the lip clearance of the die are B, the value of B / A is 10 or less when the thickness of the film is 70 μm or more and less than 100 μm, and 15 or less when 50 μm or more and less than 70 μm. If it is 50 μm or less, it is 20 or less, and, assuming that the glass transition temperature of the amorphous thermoplastic resin is Tg, the contact point between the cooling roll and the film when the film is brought into close contact with the cooling roll. The film temperature immediately before is set to Tg + 30 ° C. or higher.

As shown in FIG. 4, in this manufacturing method, the molten resin composed of the amorphous thermoplastic resin is extruded from the die 11 having the lip clearance B, and the cooling roll 1
3 is supplied. Film 1 on the outer surface of the cooling roll 13
When the glass transition temperature of the amorphous thermoplastic resin is set to Tg, the film temperature immediately before 2 is adhered is set to Tg + 30 ° C. or higher. When the thickness of the film immediately after being brought into close contact with the cooling roll is A, the value of B / A is set as described above. In order to set the above B / A to the above specific range, with respect to the target thickness of the optical film,
A method of adjusting the lip clearance B of the die 11 can be used.

However, when the amorphous thermoplastic resin having a high melt viscosity is extruded, the lip clearance B may not be reduced due to the resin pressure applied to the lip of the die 11. In that case, the lip clearance B may be reduced by increasing the resin temperature to reduce the melt viscosity or reducing the resin extrusion rate.

When the B / A ratio, that is, the draw ratio becomes larger than the above specific value, the temperature of the resin becomes low in the air gap, and when the resin is stretched, the residual retardation in the obtained optical film tends to become large. .

As described above, the B / A ratio is set to 20 or less,
Moreover, when the film is brought into close contact with the cooling roll, the film temperature immediately before the contact point between the cooling roll and the film is Tg + 3.
By setting the temperature to 0 ° C. or higher, the stress generated in the resin in the air gap is reduced, whereby an optical film having a small residual retardation can be provided.

The method for producing an optical film according to the seventh invention of the present application is the sheet manufacturing method according to any one of the fourth to sixth inventions of the present application, in which the film is extruded from a die attached to an extruder. When the film made of the amorphous thermoplastic resin is brought into close contact with the cooling roll, the film is kept warm in the air gap from the die outlet to immediately before the contact point with the cooling roll.

That is, the film temperature is controlled just before the contact with the cooling roll by keeping the film warm in the air gap. In this case,
As shown in, the temperature control can be performed with higher accuracy compared to the method of changing the mold temperature, and the temperature variation in the width direction of the film is reduced. Especially, the temperature control can be performed with high accuracy like the norbornene resin. It is effective for the resin required to be performed. Further, since it is not necessary to raise the mold temperature excessively, there is an advantage that the deterioration of the resin is suppressed.

The heat retention in the air gap is preferably such that the resin has a temperature of Tg + 30 ° C. or higher, more preferably Tg + 50 ° C. or higher, and particularly preferably Tg + 50 ° C. or higher.
It is + 80 ° C or higher. In particular, by setting the heat retention to a temperature of Tg + 80 ° C. or higher, the residual retardation of the optical film can be suppressed to 3 nm or less.

The means for keeping heat in the air gap is as follows.
An appropriate heating source such as a heater or a heat retaining box or a heat retaining device may be attached in the air gap without changing the conditions of the die and the air gap. The length of the air gap to be kept warm may be appropriately designed usually in the range of 30 to 150 mm.

The method for producing an optical film according to an eighth aspect of the present invention is the method for producing an optical film according to any one of the fourth to seventh aspects of the present application, wherein the film is attached to the cooling roll at the contact point with the cooling roll. The film is brought into close contact with the cooling roll by being pressed by or being sucked from the cooling roll side.

By forcibly bringing the film into close contact with the cooling roll at the contact point between the cooling roll and the film, the contact point of the film with respect to the cooling roll is stabilized over the entire surface, resulting in further variation in the optical axis. Can be made smaller.

In the method for producing an optical film according to the present invention, the contact stabilizing method for forming a film by forcing the molten resin discharged from the die into close contact with a cooling roll to form a film is not limited, For example, an ordinary device that can apply a uniform force in the width direction, such as an air chamber, a vacuum nozzle, electrostatic pinning, and a touch roll may be used.

Although the temperature of the cooling roll in the method for producing an optical film according to the present invention varies depending on the resin used, it is preferably in the range of Tg to Tg-100 ° C. of the resin as a whole.

The amorphous thermoplastic resin used in the optical film according to the present invention is a polymer that maintains an amorphous state with almost no crystal structure, and its Tg varies depending on the resin, but is not particularly limited. Generally, the temperature is 100 ° C or higher.

Examples of the above-mentioned amorphous thermoplastic resin include polysulfone, polymethylmethacrylate, polystyrene, polycarbonate, polyvinyl chloride, norbornene-based resin and the like, and among them, saturated norbornene-based resin is preferable. Used for. These amorphous thermoplastic resins may be used alone or in combination of two or more kinds.

Examples of the saturated norbornene-based resin include ring-opening polymer hydrogenated products of norbornene-based monomers, addition-type polymers of norbornene-based monomers and olefins, addition polymers of norbornene-based monomers and their derivatives, and the like. Is mentioned. These saturated norbornene-based resins may be used alone or in combination of two or more kinds.

Examples of the norbornene-based monomer include bicyclo [2,2,1] hept-2-ene (norbornene), 6-methylbicyclo [2,2,1] hept-2-ene, 5,6. -Dimethylbicyclo [2,2,2
1] hept-2-ene, 1-methylbicyclo [2,2,2]
1] hept-2-ene, 6-ethylbicyclo [2,2,2]
1] hept-2-ene, 6-n-butylbicyclo [2,2]
Norbornene such as 2,1] hept-2-ene, 6-isobutylbicyclo [2,2,1] hept-2-ene, and 7-methylbicyclo [2,2,1] hept-2-ene, and their substitution products Examples thereof include, but are not limited to, bicyclic compounds such as tricyclic or higher norbornene-based monomers and substituted compounds thereof.

As the hydrogenated product of the ring-opening polymer of the norbornene-based monomer, those obtained by subjecting the norbornene-based monomer to ring-opening polymerization by a known method and then hydrogenating the remaining double bond are widely used. Used. This may be a homopolymer or a copolymer of norbornene-based monomers, or a copolymer of norbornene-based monomers and other cyclic olefin-based monomers.

Further, examples of the addition type polymer of the norbornene-based monomer and the olefin include a copolymer of the norbornene-based monomer and the α-olefin. The α-olefin has 2 to 20 carbon atoms, preferably 2 to 10 carbon atoms, for example, ethylene, propylene, 1-butene, 3-methyl-1-butene, 1-pentene, 3-methyl-1. -Pentene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-decene, 1
-Dodecene, 1-tetradecene, 1-hexadecene, and the like. Among them, ethylene is preferable because of high copolymerizability, and ethylene is present even when other α-olefin is copolymerized with a norbornene-based monomer. The copolymerizability is improved by increasing the temperature.

[0048]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the embodiments and specific examples of the optical film according to the present invention will be explained.
The present invention will be clarified.

In the following, the residual phase difference and the optical axis shift are referred to as "KOBRA-21A" manufactured by Oji Scientific Instruments.
DH "is a value measured at a measurement wavelength of 590 nm. Specifically, the residual retardation was measured at all points at a 50 mm pitch after cutting both ends in the width direction of the obtained film by 10% of the width direction dimension respectively, and also in the flow direction (length direction). ) Is measured at 1m pitch at 3 points,
The average of these measurements is shown. Further, the optical axis shift was set to 0 ° in the average optical axis direction.

Resin used: saturated norbornene resin (manufactured by Nippon Zeon Co., Ltd., trade name "Zeonor 1600", T
g = 168 ° C.), polysulfone resin (manufactured by Teijin Amoco Engineering Plastics, trade name “Udel 35”)
00 ", Tg = 193 ° C).

Extruder: Internal diameter 50 mm, L / D = 2
8. Single screw extruder, the extrusion temperature was adjusted at 270 to 320 ° C. T-die: A coat hanger type with a width of 500 mm was used. Cooling roll: A roll equipped with an air chamber was used, and the temperature was 140 ° C.

In the following examples and comparative examples, a film having a width of 430 mm and a thickness of 40 μm was produced using the above apparatus.

(Example 1) A saturated norbornene-based resin was used and extruded with a mold temperature of 310 ° C and an air gap of 80 mm. When the film temperature immediately before the contact with the cooling roll was measured with a radiation thermometer, it was 220 ° C., the average residual phase difference was 9.50 nm, and the optical axis deviation was ± 7 °.
Met.

Example 2 A saturated norbornene resin was extruded at a mold temperature of 310 ° C. and an air gap of 70 mm.
The film temperature immediately before contact with the cooling roll was 250 ° C, the residual phase difference was 2.75 nm on average, and the optical axis deviation was ± 7 °.
Met.

Example 3 Saturated norbornene-based resin was extruded at a mold temperature of 290 ° C. with an air gap of 80 mm, and a heater was placed at a distance of 30 mm from the film in the air gap to keep the film warm. The film temperature immediately before the contact was 232 ° C, the average residual retardation was 9.00 nm, and the optical axis deviation was ± 7 °.
Met.

Example 4 A saturated norbornene resin was extruded with a mold temperature of 290 ° C. and an air gap of 70 mm, and a heater was installed at a position 30 mm away from the film in the air gap to keep the film warm.
The film temperature immediately before contact with the cooling roll was 258 ° C, the residual phase difference was 2.50 nm on average, and the optical axis deviation was ± 7 °.
Met.

Example 5 Using polysulfone resin,
Extrusion was performed with the mold temperature set at 310 ° C. and the air gap set at 80 mm. 30 mm from the film in the air gap
When a heater is installed at a remote place to keep the film warm, the film temperature immediately before contact with the cooling roll is 250 ° C.
The average residual phase difference is 8.90 nm, and the optical axis deviation is ±
It was 7 °.

Example 6 Polysulfone resin was extruded with a mold temperature of 320 ° C. and an air gap of 70 mm, and a heater was installed at a position 30 mm away from the film in the air gap to keep the film warm. The film temperature immediately before was 278 ° C., the average residual retardation was 2.90 nm, and the optical axis deviation was ± 7 °.

(Embodiment 7) The lip clearance is set to 500.
μm, film thickness after adhesion to the cooling roll is 50μ
A film was obtained in the same manner as in Example 1 except that m (draw ratio B / A = 10). The resulting film had an average residual retardation of 5.20 nm and an optical axis shift of ± 4 °. The film temperature immediately before contact with the cooling roll at this time was 212 ° C.

(Embodiment 8) Lip clearance of 500
μm, film thickness after adhesion to the cooling roll is 30μ
A film was obtained in the same manner as in Example 1 except that m (draw ratio B / A = 17). The resulting film had an average residual retardation of 8.80 nm and an optical axis shift of ± 3 °. The film temperature immediately before the contact with the cooling roll at this time was 203 ° C.

(Example 9) Using the resin used in Example 5, the lip clearance was 500 μm, and the film thickness after being adhered to a cooling roll was 50 μm (draw ratio B / A).
= 10), and other conditions were the same as in Example 1 to obtain a film. The residual retardation of the obtained film is 6.00n on average.
m, optical axis deviation was ± 5 °. The film temperature immediately before contact with the cooling roll was 235 ° C.

Comparative Example 1 The resin used in Example 1 was extruded with a mold temperature of 290 ° C. and an air gap of 80 mm. The film temperature immediately before contact with the cooling roll was 207 ° C. The average residual retardation of the film was 12.10 nm, and the optical axis deviation was ± 7 °.

(Comparative Example 2) Using the resin used in Example 1, the lip clearance was 1000 μm, and the film thickness after being adhered to the cooling roll was 50 μm (draw ratio B).
/ A = 20), and otherwise a film was obtained in the same manner as in Example 1. The residual retardation of the obtained film is 11.6 on average.
The optical axis deviation was 0 nm and the deviation was ± 3 °. The film temperature immediately before contact with the cooling roll at this time was 195 ° C.

[0064]

In the optical film according to the first invention, the thickness is less than 100 μm, the residual retardation is 10 nm or less, and the optical axis deviation is ± 10 ° or less, so that the optical distortion is small, It is possible to provide a film suitable for optical applications such as optical disks and liquid crystal displays.

In the optical film according to the second invention, since the thickness is less than 100 μm, the residual retardation is 3 nm or less, and the optical axis deviation is ± 10 ° or less, the optical distortion is very small, It is possible to provide a film extremely suitable for optical applications such as an optical disk and a liquid crystal display.

In the manufacturing method according to the fourth aspect of the invention, since the temperature of the film from the die exit to immediately before the contact point between the cooling roll and the film is set to Tg + 50 ° C. or higher, the film with small optical distortion according to the first aspect of the invention. Can be provided.

In the manufacturing method according to the fifth aspect of the invention, the temperature of the film from the die exit to immediately before the contact point between the cooling roll and the film is set to Tg + 80 ° C. or higher. That is, it is possible to provide a film having very small optical distortion according to the second invention.

In the manufacturing method according to the sixth aspect of the invention, the draw ratio B / A is set to a specific value, and the temperature immediately before the film is brought into close contact with the cooling roll is Tg + 30 ° C. or higher. The thickness is less than 100 μm, the residual phase difference is 10 nm or less, and the optical axis shift is ± 10 °.
It is possible to reliably provide the following optical film according to the first invention.

The optical film according to the present invention and the optical film obtained by the production method according to the present invention have a small optical strain, and thus are used as a raw film uniaxially or biaxially or in an oblique direction. It can also be suitably used for various retardation compensation films formed by stretching and orientation.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between a distance from an exit of a die and a film temperature in the present invention.

FIG. 2 is a diagram showing a relationship between a distance from an exit of a die and a film temperature in the present invention.

FIG. 3 is a diagram showing the relationship between the distance from the die exit and the film temperature when the film is kept warm in the air gap in the present invention.

FIG. 4 is a schematic cross-sectional view for explaining an optical film molding step between a die slip and a cooling roll in the manufacturing method according to the sixth aspect of the invention.

[Explanation of symbols]

11 ... Dice 12 ... film 13 ... Cooling roll

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) // B29K 45:00 B29K 45:00 B29L 11:00 B29L 11:00 (72) Inventor Katsumi Nishimura Kyoto City 2-2 Kamitobagami-chochocho, Minami-ku Sekisui Kagaku Kogyo Co., Ltd. F-term (reference) 2H090 JB03 JB06 JB13 JC06 JC07 JD01 JD05 LA05 LA06 LA07 LA08 LA09 2H091 FA08X FA08Z FA11X FA11Z FB02 FC07 FC22 GA01 GA07 GA16 KA10 LA03 LA16 LA16 LA16 LA207 AA12 AG01 AH73 AR06 AR12 KA01 KA17 KK64 KL76 KL84 KM15 KM16

Claims (8)

[Claims] 1. An optical film extruded using an amorphous thermoplastic resin, having a thickness of less than 100 μm, a residual retardation of 10 nm or less, and an optical axis deviation of ± 10 ° or less. Is an optical film. 2. An optical film extruded using an amorphous thermoplastic resin, having a thickness of less than 100 μm, a residual retardation of 3 nm or less, and an optical axis deviation of ± 10 ° or less. Is an optical film. 3. The optical film according to claim 1, wherein the amorphous thermoplastic resin is a saturated norbornene-based resin. 4. When the glass transition temperature of the amorphous thermoplastic resin is Tg, a film made of the amorphous thermoplastic resin extruded in a sheet form from a die attached to an extruder is closely attached to a cooling roll. The film temperature immediately before the contact between the cooling roll and the film is Tg + 50
The temperature is set to not less than 0 ° C, and the method for producing an optical film according to claim 1 or 3, wherein. 5. When the glass transition temperature of the amorphous thermoplastic resin is Tg, a film made of the amorphous thermoplastic resin extruded in a sheet form from a die attached to an extruder is brought into close contact with a cooling roll. The temperature of the film just before the contact between the cooling roll and the film is Tg + 80
4. The method for producing an optical film according to any one of claims 1 to 3, wherein the temperature is not lower than 0 ° C. 6. A is a thickness immediately after a film made of the amorphous thermoplastic resin extruded in a sheet shape from a die attached to an extruder is closely attached to a cooling roll, and A is a lip clearance of the die. Then, the value of B / A is 10 or less when the thickness of the film is 70 μm or more and less than 100 μm, and 50 μm or more, 70 μm
If it is less than 15, it is not more than 15; if it is less than 50 μm, it is not more than 20; The film temperature immediately before the contact between the cooling roll and the film is Tg + 30 ° C. or higher, and the method for producing an optical film according to claim 1, wherein 7. When a film made of an amorphous thermoplastic resin extruded in a sheet form from a die attached to an extruder is brought into close contact with a cooling roll, the contact between the cooling roll and the film comes out from the die outlet. The method for producing an optical film according to any one of claims 4 to 6, wherein the film is kept warm in the air gap immediately before. 8. At the contact point between the cooling roll and the film, the film is pressed against the cooling roll, or sucked from the cooling roll side,
The method for producing an optical film according to claim 4, wherein the film is closely attached to the cooling roll.