JP2007296726A - Method for manufacturing optical film, optical film, and method for manufacturing oriented film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a long cyclic olefin optical film with any phase difference and a small optical fluctuation with ease, an optical film useful as a material for an oriented film and a method for manufacturing an oriented film using the optical film. <P>SOLUTION: In a manufacturing process for the optical film, a molten cyclic olefin resin is extruded from a die and is press-stuck on a substrate to make a film, and the film is released from the substrate to take it up into a rolled shape, or alternatively the cyclic olefin resin is dissolved or dispersed in an organic solvent and is cast on a substrate, a part of the organic solvent is removed to form a film-like composition, and the film-like composition is released from the substrate and furthermore, the organic solvent is removed to take it up into a rolled shape. The method for manufacturing the optical film is characterized in that when the film is released from the substrate, the film is released at a temperature of Tg of the cyclic olefin resin -30°C to Tg+20°C by 1-30 kgf/cm<SP>2</SP>. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing an optical film from which an optical film having an arbitrary retardation is obtained by a simple method, an optical film suitable as a raw film for a stretched film, and a method for producing a stretched film using the optical film. .

Since the cyclic olefin is excellent in transparency, heat resistance, moisture resistance and the like, it is suitably used for optical film applications. Usually, a film made of a cyclic olefin resin is produced by a solution casting method (solution casting method), a melt extrusion method, or the like, and is subjected to stretching or the like as necessary.
An optical film is required to have excellent optical properties such as transparency, and it is important that the film is homogeneous and has little optical unevenness. Examples of the optical unevenness that occurs during the production of the optical film include retardation unevenness that occurs during stretching. Examples of the stretching method without such retardation unevenness include a method of adjusting the clip interval and the temperature condition in the tenter stretching method, and a method for producing a film with less optical unevenness by a simpler method is required. Yes.

JP 2005-254812 A

  The present invention provides a method for producing a long cyclic olefin-based optical film having an arbitrary phase difference and small optical unevenness by a simple method, an optical film useful as a raw material for a stretched film, and the optical film. It is an object to provide a method for producing a stretched film.

The optical film manufacturing method of the present invention (hereinafter also referred to as “manufacturing method 1”) is a method in which a molten cyclic olefin-based resin is extruded from a die and pressed onto a substrate to form a film, and the film is peeled off from the substrate. In the manufacturing process of the optical film wound up in a roll shape, in any step from peeling the film from the base material and winding it up into a roll shape, the cyclic olefin resin is subjected to a temperature of Tg-30 ° C. to Tg + 20 ° C. And having a step of applying a stress of 1 to 30 kgf / cm ² . (Tg represents the glass transition temperature. The same shall apply hereinafter.)
In the manufacturing method 1, when peeling a film from a base material, it is preferable to peel from a base material by the stress of 1-30 kgf / cm < ² > under the temperature of Tg-30 degreeC-Tg + 20 degreeC of cyclic olefin resin.

The method for producing an optical film of the present invention (hereinafter also referred to as “Production Method 2”) involves dissolving or dispersing a cyclic olefin-based resin in an organic solvent and casting it on a substrate to remove a part of the organic solvent. In the manufacturing process of the optical film, the film-like composition is peeled off from the base material and the organic solvent is further removed and wound into a roll shape. In any process until winding up into a shape, the film-shaped composition has a process of applying a stress of 1 to 30 kgf / cm ² at an apparent temperature of Tg−30 ° C. to Tg + 20 ° C. . (However, the apparent Tg of the film-like composition means a Tg measured by a DSC curve obtained by measuring the film-like composition under a temperature rising condition of 20 ° C./min. The same applies hereinafter.)
In the production method 2, when the film-like composition is peeled from the substrate, the film-like composition is exposed from the substrate at a stress of 1 to 30 kgf / cm ² under the apparent temperature of Tg−30 ° C. to Tg + 20 ° C. Peeling is preferable.

The optical film of the present invention comprises a cyclic olefin resin,
When the refractive index in the direction showing the maximum refractive index in the film plane at a light wavelength of 550 nm is nx, the refractive index in the direction perpendicular to nx in the film plane is ny, and the film thickness is d [nm],
A phase difference R0 (550) [nm] = (nx−ny) × d in the film plane is 20 nm or more and 300 nm or less, a variation in R0 is within ± 10%, and a direction showing the maximum refractive index in the film plane The maximum value of the angle formed by the film longitudinal direction is 0 ° to 10 °.
The cyclic olefin resin is preferably a resin obtained by polymerizing or copolymerizing at least one compound represented by the following formula (1).

(In Formula (1), R < ¹ > -R < ⁴ > is a hydrogen atom, a halogen atom, a C1-C30 hydrocarbon group, or another monovalent organic group, and may be the same or different. Further, any two of R ^{1 to} R ⁴ may be bonded to each other to form a monocyclic or polycyclic structure, m is 0 or a positive integer, and p is 0 or a positive integer. .)

The method for producing a stretched film of the present invention is characterized by stretching the optical film of the present invention in the film width direction or the film longitudinal direction.
The stretched film production method of the present invention is characterized by stretching the obtained optical film in the film width direction following the production method 1 or 2.

  According to the present invention, a long cyclic olefin-based optical film having an arbitrary phase difference and small optical unevenness can be produced by a simple method. In addition, an optical film that has little optical unevenness and is useful as a raw material for a stretched film can be obtained. Since the optical film and stretched film according to the present invention have very little thickness variation and little optical unevenness, a large-screen liquid crystal display using the optical film can achieve high performance without distortion and unevenness over the entire surface.

Hereinafter, the present invention will be specifically described.
Cyclic Olefin Resin The optical film according to the present invention comprises a cyclic olefin resin. As the cyclic olefin-based resin, a cyclic olefin-based compound having a norbornene skeleton represented by the above formula (1) is used alone or in combination of two or more, or together with a copolymerizable monomer other than the cyclic olefin-based compound, as a polymerization or copolymerization monomer. Any of the used addition (co) polymers, ring-opening (co) polymers, or (co) polymers obtained by hydrogenating double bonds in the main chain after ring-opening (co) polymerization are used. .
The cyclic olefin resin constituting the optical film according to the present invention is a (co) polymer obtained from a monomer represented by the following general formula (1) (hereinafter also referred to as “specific monomer”). Specifically, the following polymers (a) to (e) or copolymers (hereinafter referred to as “(co) polymers”) can be preferably used.
(A) Ring-opening polymer of specific monomer (hereinafter also referred to as “specific ring-opening polymer”)
(B) a ring-opening copolymer (hereinafter, referred to as “copolymerizable cyclic monomer”), which is a specific monomer and a cyclic monomer copolymerizable with the specific monomer (hereinafter, also referred to as “copolymerizable cyclic monomer”). , Also referred to as “specific ring-opening copolymer”.)
(C) Saturated copolymer of specific monomer and unsaturated double bond-containing compound (hereinafter also referred to as “specific saturated copolymer”)
(D) Hydrogenated (co) polymer (e) specific ring-opening polymer or specific ring-opening copolymer (hereinafter also referred to as “specific ring-opening (co) polymer”) Hydrogenated (co) polymer obtained by cyclization of ring-opened (co) polymer by Friedel-Craft reaction and hydrogenation

  Among these, the hydrogenated (co) polymer of (d) or (e) is preferably used because it has higher transparency, and more preferably, in the following general formula (1 ′) corresponding to (d) A (co) polymer having a structural unit represented, particularly preferably a (co) polymer having a structural unit represented by the following general formula (2).

(In formula (1 ′), the definitions of R ^{1 to} R ⁴ , p, and m are the same as in formula (1) above.)

(In formula (2), the definitions of R ^{1 to} R ⁴ are the same as in formula (1) above.)

[Specific monomer]
As a preferable specific monomer, in the above formula (1), R ¹ and R ³ are a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms, and R ² and R ⁴ are a hydrogen atom or a monovalent organic group. And at least one of R ² and R ⁴ represents a polar group other than a hydrogen atom and a hydrocarbon group, m is an integer of 0 to 3, p is an integer of 0 to 3, and the value of m + p is 0. -4, more preferably 0-2, particularly preferably 1.

Among the specific monomers, the specific monomer in which R ² and R ⁴ have a polar group represented by the following formula (3) has a high glass transition temperature (hereinafter also referred to as “Tg”), and moisture absorption. It is preferable at the point from which low cyclic olefin type thermoplastic resin is obtained.
^{_{- (CH 2) n COOR 5}} (3)
(Wherein, R ⁵ represents a hydrocarbon group having 1 to 12 carbon atoms, n is an integer from 0 to 5.)
In the above formula (3), R ⁵ is preferably an alkyl group. Moreover, the smaller the value of n, the higher the Tg of the resulting cyclic olefin-based resin, which is preferable. In particular, a specific monomer having n of 0 is preferable in terms of easy synthesis.

In the above formula (1), R ¹ or R ³ is preferably an alkyl group, more preferably an alkyl group having 1 to 4 carbon atoms, still more preferably an alkyl group having 1 to 2 carbon atoms, particularly A methyl group is preferred. Furthermore, it is preferable that this alkyl group is bonded to the same carbon atom as the carbon atom to which the polar group represented by the above formula (3) is bonded.
Moreover, the specific monomer whose m is 1 in the said Formula (1) is preferable at the point from which the thermoplastic resin composition with higher Tg is obtained.

As a specific example of the specific monomer represented by the above formula (1),
Bicyclo [2.2.1] hept-2-ene,
Tricyclo [5.2.1.0 ^2,6 ] -8-decene,
Tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
Pentacyclo ^{[6.5.1.1 3,6 .0 2,7 .0 9,13]} -4- pentadecene,
Pentacyclo ^{[7.4.0.1 2,5 .19 9,12 .0 8,13]} -3- pentadecene,
Tricyclo [4.4.0.1 ^2,5 ] -3-undecene,
5-methylbicyclo [2.2.1] hept-2-ene,
5-ethylbicyclo [2.2.1] hept-2-ene,
5-methoxycarbonylbicyclo [2.2.1] hept-2-ene,
5-methyl-5-methoxycarbonylbicyclo [2.2.1] hept-2-ene,
5-cyanobicyclo [2.2.1] hept-2-ene,
8 methoxycarbonyltetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8-ethoxycarbonyl tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8-n-propoxycarbonyl tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8 isopropoxycarbonyl tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8-n-butoxycarbonyl tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8-methyl-8-methoxycarbonyltetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8-methyl-8-ethoxycarbonyl tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8-methyl -8-n-propoxycarbonyl tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8-methyl-8-isopropoxycarbonyl tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8-methyl -8-n-butoxycarbonyl tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
Dimethanooctahydronaphthalene,
Ethyltetracyclododecene,
6-ethylidene-2-tetracyclododecene,
Trimethanooctahydronaphthalene,
Pentacyclo ^{[8.4.0.1 2,5 .1 9,12 .0 8,13]} -3- hexadecene,
Heptacyclo ^{[8.7.0.1 3,6 .1 10,17 .1 12,15 .0} 2,7 .0 11,16] -4- eicosene,
Heptacyclo ^{[8.8.0.1 4,7 .1 11,18 .1 13,16 .0} 3,8 .0 12,17] -5- heneicosene,
5-ethylidenebicyclo [2.2.1] hept-2-ene,
8 ethylidene tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
5-phenylbicyclo [2.2.1] hept-2-ene,
8-phenyl tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
5-fluorobicyclo [2.2.1] hept-2-ene,
5-fluoromethylbicyclo [2.2.1] hept-2-ene,
5-trifluoromethylbicyclo [2.2.1] hept-2-ene,
5-pentafluoroethylbicyclo [2.2.1] hept-2-ene,
5,5-difluorobicyclo [2.2.1] hept-2-ene,
5,6-difluorobicyclo [2.2.1] hept-2-ene,
5,5-bis (trifluoromethyl) bicyclo [2.2.1] hept-2-ene,
5,6-bis (trifluoromethyl) bicyclo [2.2.1] hept-2-ene,
5-methyl-5-trifluoromethylbicyclo [2.2.1] hept-2-ene,
5,5,6-trifluorobicyclo [2.2.1] hept-2-ene,
5,5,6-tris (fluoromethyl) bicyclo [2.2.1] hept-2-ene,
5,5,6,6-tetrafluorobicyclo [2.2.1] hept-2-ene,
5,5,6,6-tetrakis (trifluoromethyl) bicyclo [2.2.1] hept-2-ene,
5,5-difluoro-6,6-bis (trifluoromethyl) bicyclo [2.2.1] hept-2-ene,
5,6-difluoro-5,6-bis (trifluoromethyl) bicyclo [2.2.1] hept-2-ene,
5,5,6-trifluoro-5-trifluoromethylbicyclo [2.2.1] hept-2-ene,
5-fluoro-5-pentafluoroethyl-6,6-bis (trifluoromethyl) bicyclo [2.2.1] hept-2-ene,
5,6-difluoro-5-heptafluoro-iso-propyl-6-trifluoromethylbicyclo [2.2.1] hept-2-ene,
5-chloro-5,6,6-trifluorobicyclo [2.2.1] hept-2-ene,
5,6-dichloro-5,6-bis (trifluoromethyl) bicyclo [2.2.1] hept-2-ene,
5,5,6-trifluoro-6-trifluoromethoxybicyclo [2.2.1] hept-2-ene,
5,5,6-trifluoro-6-heptafluoropropoxybicyclo [2.2.1] hept-2-ene,
8-fluoro-tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene, 8-fluoromethyl-tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3-dodecene,
8 difluoromethyl tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8-trifluoromethyl-tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8 pentafluoroethyl tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8,8-difluoro-tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8,9-difluoro-tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8,8-bis (trifluoromethyl) tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8,9-bis (trifluoromethyl) tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8-methyl-8-trifluoromethyl-tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8,8,9- trifluoro-tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8,8,9- tris (trifluoromethyl) tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8,8,9,9- tetrafluoro-tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8,8,9,9- tetrakis (trifluoromethyl) tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8,8-difluoro-9,9-bis (trifluoromethyl) tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8,9-difluoro-8,9-bis (trifluoromethyl) tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8,8,9- trifluoro-9-trifluoromethyl-tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8,8,9- trifluoro-9-trifluoromethoxy-tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8,8,9- trifluoro-9-pentafluoro propoxy tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8-Fluoro-8-pentafluoroethyl-9,9-bis (trifluoromethyl) tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8,9-difluoro-8-heptafluoro-iso- propyl-9-trifluoromethyl-tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8-Chloro -8,9,9- trifluoro tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8,9-dichloro-8,9-bis (trifluoromethyl) tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
8- (2,2,2-trifluoroethoxy-carbonyl) tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene,
, And the like 8-methyl-8- (2,2,2-trifluoroethoxy-carbonyl) tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene.

Of these specific monomers, 8-methyl-8-methoxycarbonyltetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3- dodecene, 8-ethylidene tetracyclo [4.4 .0.1 ^2,5 .1 ^7,10] -3-dodecene, 8-ethyl tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] -3-dodecene, pentacyclo [7.4 .0.1 ^2,5 .1 ^9,12 .0 ^8,13] -3-pentadecene are preferred in that the cyclic olefin resin having excellent heat resistance is obtained.

[Copolymerizable cyclic monomer]
As the copolymerizable cyclic monomer for obtaining a specific ring-opening copolymer, it is preferable to use a cycloolefin having 4 to 20 carbon atoms, particularly 5 to 12 carbon atoms. Specific examples thereof include cyclobutene and cyclopentene. , Cycloheptene, cyclooctene, tricyclo [5.2.1.0 ^2,6 ] -3-decene, 5-ethylidene-2-norbornene, dicyclopentadiene, and the like.

[Unsaturated double bond-containing compound]
Examples of the unsaturated double bond-containing compound for obtaining a specific saturated copolymer include polybutadiene, polyisoprene, styrene-butadiene copolymer, ethylene-nonconjugated diene copolymer, and carbon- An unsaturated hydrocarbon polymer containing a carbon-carbon double bond can be used.

The ratio of the specific monomer and the copolymerizable cyclic monomer or unsaturated double bond-containing compound used is the weight ratio of the specific monomer: copolymerizable cyclic monomer or unsaturated double bond-containing compound. It is preferably 100: 0 to 50:50, and more preferably 100: 0 to 60:40.
When the proportion of the copolymerizable cyclic monomer or unsaturated double bond-containing compound is excessive, the Tg of the resulting copolymer is lowered, and as a result, the heat resistance of the resin is lowered. It becomes difficult to obtain a film with high properties.

(Ring-opening polymerization catalyst)
The ring-opening polymerization reaction of the specific monomer is performed in the presence of a metathesis catalyst. The metathesis catalyst includes at least one metal compound selected from a tungsten compound, a molybdenum compound, and a rhenium compound (hereinafter referred to as “component (a)”), and a Group 1 element (for example, Li, Na, K) of the periodic table. Etc.), Group 2 elements (eg Mg, Ca etc.), Group 12 elements (eg Zn, Cd, Hg etc.), Group 13 elements (eg B, Al etc.), Group 4 elements (eg Ti, Zr etc.) Or at least one compound selected from those having at least one element-carbon bond or the element-hydrogen bond (hereinafter referred to as a compound of a Group 14 element (for example, Si, Sn, Pb, etc.)). And “(b) component”), and may contain an additive (hereinafter referred to as “(c) component”) in order to enhance the catalytic activity. There.

Specific examples of suitable metal compounds constituting the component (a) include metal compounds described in JP-A-1-240517 such as WCl ₆ , MoCl ₅ , and ReOCl ₃ .
Specific examples of the compound constituting the component (b) include n-C ₄ H ₉ Li, (C ₂ H ₅ ) ₃ Al, (C ₂ H ₅ ) ₂ AlCl, (C ₂ H ₅ ) _1.5 AlCl _1.5 , (C ₂ H ₅ ) AlCl ₂ , methylalumoxane, LiH and the like, compounds described in JP-A-1-240517 can be mentioned.
As the component (c), alcohols, aldehydes, ketones, amines and the like can be preferably used, but other compounds shown in JP-A-1-240517 can be used.

[Hydrogenation]
The cyclic olefin-based resin used in the present invention is obtained by hydrogenating a specific (co) ring-opening polymer in addition to the specific (co) ring-opening polymer and the specific saturated copolymer. A hydrogenated (co) polymer obtained by cyclizing a hydrogenated (co) polymer and a specific (co) ring-opened polymer by Friedel-Craft reaction and then hydrogenating it can be used.
Since such a hydrogenated (co) polymer has excellent thermal stability, it can prevent its properties from being deteriorated by heating when it is molded or used as a product. it can.
Here, the hydrogenation rate in the hydrogenated (co) polymer is usually 50% or more, preferably 70% or more, more preferably 90% or more, still more preferably 95% or more, and particularly preferably 97% or more.

The cyclic olefin resin used in the present invention preferably has an intrinsic viscosity (η _inh ) measured in chloroform at 30 ° C. of 0.2 to 5.0 dl / g.
The average molecular weight of the cyclic olefin resin is 8,000 to 100,000 in terms of polystyrene-equivalent number average molecular weight (Mn) measured by gel permeation chromatography (GPC), and 20,200 in weight average molecular weight (Mw). The thing of the range of 000-300,000 is suitable.
Furthermore, it is preferable that the Vicat softening point of cyclic olefin resin is 110 degreeC or more.
Moreover, the cyclic olefin resin film used by this invention may be formed from the resin composition containing the above cyclic olefin resins. In addition to the cyclic olefin-based resin, various additives that can be blended with resins such as resin components other than the cyclic olefin-based resin, stabilizers and processability improvers can be blended in the resin composition.

Manufacturing method of optical film The optical film according to the present invention is obtained by forming the above-mentioned cyclic olefin-based resin into a film, and is usually a continuous film, preferably a length in the longitudinal direction. Is a form of a film roll obtained by winding a film of 50 m or more into a roll.
The method for forming the cyclic olefin-based resin into a film is not particularly limited, but a melt molding method such as a melt extrusion method, or a solution casting method (solvent casting method) is preferable. In any case, in the process until the film is wound into a roll, the film (the cyclic olefin resin itself in the case of the melt extrusion method, the cyclic olefin resin and the organic solvent in the case of the solution casting method). Including a step of applying a stress of 1 to 30 kgf / cm ² at a temperature of Tg−30 ° C. to Tg + 20 ° C. By having this step, the phase difference in the film plane at a light wavelength of 550 nm is 20 nm or more and 300 nm or less, the variation of R0 is within ± 10%, and the direction indicating the maximum refractive index in the film plane and the film length It becomes possible to easily obtain an optical film with a minimum of optical unevenness in which the maximum value of the angle formed by the direction is 0 ° to 10 °.

[Melt extrusion method]
The melt extrusion method is not particularly limited. For example, a known uniaxial extruder or biaxial extruder is used as a melt extruder to melt a cyclic olefin-based resin that is a molded resin material. A method can be used in which a cyclic olefin resin (hereinafter also referred to as “molten resin”) in a state is quantitatively measured with a gear pump and extruded into a film form from a die having a slit-like outlet.
Further, the extruder is preferably provided with a polymer filter for removing foreign matters in the molding resin material quantified by the gear pump, and foreign matters such as burns and gels generated during the melt extrusion process.

Here, as an extruder, that whose L / D is 28-40 is preferable, and the screw diameter is 30-125 mm normally, although it changes with extrusion amounts. If the screw diameter is less than 30 mm, the metering stability and film productivity may be reduced. On the other hand, if the screw diameter is more than 125 mm, the measured molten resin stays and is attributed to this. May cause thermal degradation.
As the gear pump, since the molten resin can be discharged smoothly, the external pump is preferably used. As the die, a T die is usually used. Examples of the T die include a coat hanger die and a fish tail die. Among these, a coat hanger die is preferable. In addition, the manifold is not particularly limited, but a manifold having a structure in which stagnation hardly occurs is preferably used from the viewpoint of suppressing thermal deterioration of the molded resin material.
As the polymer filter, since a molten resin can be prevented from staying, a leaf disk type filter is preferably used. The filtration accuracy of the polymer filter is usually 20 μm or less, preferably 10 μm or less. When the filtration accuracy exceeds 20 μm, impurities may pass through the polymer filter, and the resulting specific laminate may have poor appearance such as black defects.

  The film-like resin extruded from the die is usually formed into a film by cooling the pressure bonding to the substrate. As the substrate, a metal roll or a belt-shaped substrate, or a roll-shaped substrate whose surface is coated with a ceramic such as aluminum oxide or chromium oxide is preferably used. Examples of the film forming method include a nip roll method, an electrostatic application method, an air knife method, a calendar method, a single-sided belt method, a double-sided belt method, a three-roll method, and the like. A three-roll system or a single-sided belt system is preferably used. In the single-sided belt type, a film manufacturing apparatus called a sleeve type is preferably used. For example, there is a film manufacturing apparatus in which a mirror roll and a metal belt are arranged below the discharge port of the die, and a peeling roll is arranged in parallel with the mirror roll. The metal belt is held in a state where tension is applied by two holding rolls provided so as to be in contact with the inner surface thereof. The resin discharged from the discharge port is pressed between the mirror roll and the metal belt, transferred to the mirror roll and cooled, and then peeled off by the peeling roll to form a film.

In the production method 1 of the present invention, in any step from peeling the film from the substrate to winding it into a roll by melt extrusion, the cyclic olefin-based resin is subjected to a temperature of Tg-30 ° C to Tg + 20 ° C. And having a step of applying a stress of 1 to 30 kgf / cm ² . Preferably, when peeling a film from a base material, it peels from a base material with the stress of 1-30 kgf / cm < ² > under the temperature of Tg-30 degreeC-Tg + 20 degreeC of cyclic olefin resin. The temperature condition is preferably Tg−20 ° C. to Tg + 10 ° C., more preferably Tg−10 ° C. to Tg + 5 ° C., and the stress is preferably 5 to 30 kgf / cm ² , more preferably 10 to 20 kgf / cm ² . is there.

[Solution casting method]
As the solution casting method (solvent casting method), for example, a cyclic olefin-based resin is dissolved or dispersed in an organic solvent to obtain a liquid having an appropriate concentration, and poured or applied onto a suitable substrate (carrier). The method of making it peel from a base material after drying is mentioned.
When the cyclic olefin-based resin is dissolved or dispersed in a solvent, the concentration of the resin is usually 0.1 to 90% by weight, preferably 1 to 50% by weight, and more preferably 10 to 35% by weight. If the concentration of the resin is less than the above, it is difficult to ensure the thickness of the film. Moreover, problems such as difficulty in obtaining the surface smoothness of the film due to foaming associated with solvent evaporation occur. On the other hand, a concentration exceeding the above is not preferable because the viscosity and the surface of the optical film obtained due to the solution viscosity becoming too high become difficult to be uniform.
The viscosity of the solution at room temperature is usually 1 to 1,000,000 (mPa · s), preferably 10 to 100,000 (mPa · s), more preferably 100 to 100,000 (mPa · s). s), particularly preferably 1,000 to 10,000 (mPa · s).

Solvents used here include aromatic solvents such as benzene, toluene, xylene, cellosolve solvents such as methyl cellosolve, ethyl cellosolve, 1-methoxy-2-propanol, diacetone alcohol, acetone, cyclohexanone, methyl ethyl ketone, 4 -Ketone solvents such as methyl-2-pentanone, cyclohexanone, ethylcyclohexanone, 1,2-dimethylcyclohexane, ester solvents such as methyl lactate and ethyl lactate, 2,2,3,3-tetrafluoro-1-propanol, Examples thereof include halogen-containing solvents such as methylene chloride and chloroform, ether solvents such as tetrahydrofuran and dioxane, and alcohol solvents such as 1-pentanol and 1-butanol.
In addition to the above, the SP value (solubility parameter) is usually 10 to 30 (MPa ^1/2 ), preferably 10 to 25 (MPa ^1/2 ), more preferably 15 to 25 (MPa ^1/2 ), particularly Preferably, if a solvent in the range of 15 to 20 (MPa ^1/2 ) is used, a film with good surface uniformity and optical properties can be obtained.
The said solvent can be used individually or in combination of 2 or more types. When two or more solvents are used in combination, the SP value as a mixture can be determined from the weight ratio. For example, in the case of two mixtures, the weight fraction of each solvent is W1, W2, and SP The SP value of the mixed solvent having values SP1 and SP2 is represented by the following formula:
SP value = W1 · SP1 + W2 · SP2
It can obtain | require as a value calculated by.

In the preparation of the cyclic olefin resin solution, the temperature for dissolving the cyclic olefin resin with a solvent may be room temperature or high temperature. A uniform solution can be obtained by thorough stirring. In addition, when coloring as needed, the coloring agent of a dye and a pigment can also be suitably added to a solution.
Further, a leveling agent may be added to improve the surface smoothness of the film. Any general leveling agent can be used. For example, a fluorine nonionic surfactant, a special acrylic resin leveling agent, a silicone leveling agent, and the like can be used.

  As a method for producing the film used in the present invention by the solution casting method, the solution is used by using a die or a coater, such as a metal drum (cast drum), a steel belt, a belt such as a polytetrafluoroethylene belt, polyethylene terephthalate ( Generally, a method of coating on a substrate such as a polyester film (base film) such as PET) or polyethylene naphthalate (PEN), and then drying and removing the solvent to peel from the substrate is generally used. In the present invention, all the solvent is not removed before peeling from the base material, and the film-like composition containing the resin and the solvent is peeled off from the base material and further dried to remove the solvent to obtain an optical film. It is preferable. The film-like composition is preferably peeled from the base material in a state of containing 5 to 30% by weight, preferably 5 to 20% by weight of the solvent. Moreover, it can also manufacture by apply | coating a resin solution to a base material using means, such as spray, brush, roll spin coating, and dipping, and drying and removing a solvent after that, and peeling from a base material. The thickness and surface smoothness may be controlled by repeating the coating.

  Moreover, when using base films, such as a polyester film, as a base material, you may use the film by which surface treatment was carried out. As a surface treatment method, a hydrophilic treatment method generally performed, for example, a method of laminating an acrylic resin or a sulfonate group-containing resin by coating or lamination, or a hydrophilic property of the film surface by corona discharge treatment or the like. The method etc. which improve are mentioned. In the present invention, a cast drum, a belt or a base film is preferably used as the substrate.

  There is no particular limitation on the drying (solvent removal) step of the film-like composition after peeling from the substrate or from the substrate, and there is no particular limitation. For example, a method of passing through a drying furnace through a number of rollers. However, if bubbles are generated as the solvent evaporates in the drying process, the film properties will be significantly reduced. To avoid this, the drying process is divided into two or more stages, and the temperature in each process. Alternatively, it is preferable to control the air volume.

The amount of residual solvent in the finally obtained optical film is usually 10% by weight or less, preferably 5% by weight or less, more preferably 1% by weight or less, and particularly preferably 0.5% by weight or less. Here, if the amount of residual solvent is more than 10% by weight, the dimensional change with time becomes large when the film is actually used, which is not preferable. Further, the residual solvent is not preferable because Tg is lowered and heat resistance is also lowered. In addition, the film peeled off from the base material and dried is usually wound up in a roll shape.
In addition, in order to perform the extending | stretching process mentioned later suitably, it is necessary to adjust the said residual solvent amount suitably within the said range. Specifically, in order to stably and evenly express the phase difference during stretching orientation, the residual solvent amount is usually 10 to 0.1% by weight, preferably 5 to 0.1% by weight, more preferably 1 May be -0.1 wt%. By leaving a trace amount of the solvent, stretching may be facilitated or phase difference may be easily controlled.

In the production method 2 of the present invention, the cyclic olefin-based resin is dissolved or dispersed in an organic solvent and cast onto a base material, and a part of the organic solvent is removed to obtain a film composition. In the production process of an optical film that peels off the film-like composition and further removes the organic solvent and winds up in a roll shape, in any step until the film-like composition is peeled off from the substrate and wound up in a roll shape, It has the process of applying the stress of 1-30 kgf / cm < ² > under the temperature of the apparent Tg-30 degreeC-Tg + 20 degreeC of the said film-form composition. The apparent Tg of the film-like composition referred to here is a Tg measured by a DSC curve obtained by measuring the film-like composition under a temperature rising condition of 20 ° C./min. Specifically, the DSC measured under the above conditions. The temperature at the inflection point of the curve. In the production method 2, preferably, when the film-like composition is peeled from the substrate, the film-like composition has an apparent temperature of Tg-30 ° C. to Tg + 20 ° C. and a stress of 1 to 30 kgf / cm ² . Peel from the substrate. The temperature condition is preferably Tg−20 ° C. to Tg + 10 ° C., more preferably Tg−10 ° C. to Tg + 5 ° C., and the stress is preferably 5 to 30 kgf / cm ² , more preferably 10 to 20 kgf / cm ² . is there.

Optical film The optical film of the present invention is composed of the above-mentioned cyclic olefin resin, and the refractive index in the direction showing the maximum refractive index in the film plane at a light wavelength of 550 nm is nx, and the refractive index in the direction orthogonal to nx in the film plane. When the refractive index is ny and the film thickness is d [nm], the in-plane retardation R0 (550) [nm] = (nx−ny) × d is 20 nm or more and 270 nm or less, and R0 variation is ± 10%. And the maximum value of the angle (hereinafter also referred to as “θ ₁ ”) formed by the direction indicating the maximum refractive index within the film plane and the film longitudinal direction is 0 ° to 10 °.

The in-plane retardation (R0 (550)) at a light wavelength of 550 nm is 20 nm to 300 nm, preferably 50 nm to 280 nm, and particularly preferably 100 nm to 280 nm. When the retardation in the film plane is less than 20 nm, the properties as a retardation film are insufficient, and when it exceeds 300 nm, there is a problem that the performance cannot be exhibited when the retardation film is used. Further, the variation of R0 is within ± 10%, preferably within ± 5%, particularly preferably within ± 3%.
The θ ₁ is 0 ° to 10 °, preferably 0 ° to 5 °, and particularly preferably 0 ° to 1 °. When θ ₁ exceeds 10 °, there arises a problem that when the optical film is used as a polarizing plate or the like and incorporated in a display element such as a liquid crystal panel, a change in contrast ratio varies depending on the direction in which the display element is observed.

The optical film of the present invention further has a film thickness direction retardation Rth (550) = {(nx + ny) / 2−nz} × d (where nz is a refractive index in the film thickness direction) of 30 nm to 200 nm. It is preferable that it is 50 nm-200 nm. Moreover, it is preferable that the maximum value of the angle (henceforth "(theta) ₂ ") which the direction which shows the refractive index of a film thickness direction and the normal with respect to a film surface make is 0 degrees-5 degrees, and 0 degrees-1 More preferably, it is °.
The optical film of the present invention can be suitably obtained by the production method 1 or the production method 2 described above. The obtained optical film may be subjected to stretching as described below as it is to be a stretched film, or may be wound up into a roll once to be a film roll.

The thickness of the optical film used in the present invention is usually 1 to 500 μm, preferably 1 to 300 μm, and more preferably 2 to 200 μm. When the thickness is less than 2 μm, handling becomes substantially difficult. On the other hand, in the case of 500 μm or more, when the film is wound up in a roll shape, a so-called “winding” is attached, and handling in post-processing or the like may be difficult.
The thickness distribution of the optical film used in the present invention is usually within ± 20% of the average value, preferably within ± 10%, more preferably within ± 5%, and particularly preferably within ± 1%. The thickness variation per 1 cm is usually 10% or less, preferably 5% or less, more preferably 1% or less, and particularly preferably 0.5% or less. By controlling the thickness in this way, an optical film having a smaller in-plane retardation distribution and uniform optical properties and a stretched film obtained therefrom can be obtained.
The optical film of the present invention is excellent in properties such as transparency, heat resistance, water resistance, chemical resistance and optical uniformity, and thus can be used for optical film applications such as a protective film as it is. Furthermore, it can be suitably used for the purpose of producing a highly uniform retardation film by performing stretching for expressing the retardation.

Method for Producing Stretched Film The method for producing a stretched film of the present invention is characterized by further stretching the optical film of the present invention in the film width direction or the film longitudinal direction. In addition, by adjusting the in-plane retardation in the optical film of the present invention to an arbitrary value, a stretched film obtained by performing biaxial stretching in the normal longitudinal direction and the width direction is stretched only in the width direction. It becomes possible to get in. Further, the optical film of the present invention may be further stretched in the longitudinal direction to further develop an in-plane retardation.
As stretching conditions, the cyclic olefin resin constituting the optical film is maintained at a temperature of Tg-10 ° C to Tg + 20 ° C, preferably Tg-5 ° C to Tg + 15 ° C, and 1.1 to 5.0 in the width direction or the longitudinal direction. An optically uniform film is produced by stretching within a range of 1.5 times, preferably 1.5 to 2.5 times.
As an apparatus used for stretching the film in the present invention, a tenter type transverse stretching machine is preferably used, but a simultaneous biaxial stretching machine can also be used.
The speed at which the film is stretched is usually 1 to 5,000% / min, preferably 50 to 1,000% / min, more preferably 100 to 1,000% / min, particularly preferably. 100-500% / min.
The stretched film may be cooled as it is, but it is heat set by holding it in a temperature atmosphere of Tg-20 ° C. to Tg for at least 10 seconds, preferably 30 seconds to 60 minutes, more preferably 1 minute to 60 minutes. It is preferable to do. Thereby, a stable stretched film with little change over time in the retardation of transmitted light can be obtained.

  The stretched film according to the present invention is suitably used as a retardation film. For example, the stretched film can be laminated on at least one surface of a polarizing film (polarizer) to form a polarizing plate. The stretched film according to the present invention and the polarizing plate can be used for various optical components. For example, various liquid crystal displays according to the present invention, such as mobile phones, digital information terminals, pagers, navigation, in-vehicle liquid crystal displays, liquid crystal monitors, dimming panels, displays for OA devices, displays for AV devices, electroluminescence display elements or It can be used for touch panels. It is also useful as a wave plate used in an optical disk recording / reproducing apparatus such as a CD, CD-R, MD, MO, and DVD.

EXAMPLES Hereinafter, although this invention is demonstrated further more concretely based on an Example, this invention is not limited to these Examples. In the following, “parts” and “%” mean “parts by weight” and “% by weight” unless otherwise specified.
In the following examples, glass transition temperature, saturated water absorption, total light transmittance, in-plane retardation of transmitted light, optical axis tilt angle in the film thickness direction, transmittance and polarization degree of polarizing plate, reflectance, The number of bright spots and scratch resistance were measured by the following methods.

[Glass transition temperature (Tg)]
Using a differential scanning calorimeter (DSC) manufactured by Seiko Instruments Inc., the glass transition temperature was measured in a nitrogen atmosphere under a temperature rising rate of 20 ° C./min.
[Saturated water absorption]
In accordance with ASTM D570, the sample was immersed in water at 23 ° C. for 1 week, the change in the weight of the sample before and after immersion was measured, and the saturated water absorption was determined from the value.
[Total light transmittance]
The total light transmittance was measured using a haze meter “HM-150 type” manufactured by Murakami Color Research Laboratory.
[Optical characteristics (R0, Rth, θ ₁ , θ ₂ )]
Measurement was performed at a wavelength of 550 nm using “KOBRA-21ADH” manufactured by Oji Scientific Instruments.
[Transmissivity and degree of polarization of polarizing plate]
Using “KOBRA-21ADH” manufactured by Oji Scientific Instruments, the transmittance and degree of polarization of the polarizing plate were measured. The measurement wavelength was 550 nm.

<Synthesis Example 1>
In a reaction vessel purged with nitrogen, 8-methyl-8-carboxymethyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene, 225 parts, 25 parts of bicyclo [2.2.1] hept-2-ene as a specific monomer, 27 parts of 1-hexene as a molecular weight regulator, and toluene 750 as a solvent. The solution was heated to 60 ° C. Next, 0.62 parts of a toluene solution containing 1.5 mol / l of triethylaluminum as a polymerization catalyst and tungsten hexachloride modified with t-butanol and methanol (t-butanol: methanol: tungsten) were added to the solution in the reaction vessel. = 0.35 mol: 0.3 mol: 1 mol) containing 3.7 parts of a 0.05 mol / l toluene solution, and heating and stirring the system at 80 ° C. for 3 hours. A ring-opening copolymer solution was obtained by a ring copolymerization reaction.
1,000 parts of the ring-opening polymer solution thus obtained was charged into an autoclave, and 0.12 part of RuHCl (CO) [P (C ₆ H ₅ ) ₃ ] ₃ was added to the ring-opening polymer solution. Then, under the conditions of a hydrogen gas pressure of 100 kg / cm ² and a reaction temperature of 165 ° C., the mixture was heated and stirred for 3 hours to carry out a hydrogenation reaction, and after cooling the resulting reaction solution (hydrogenated polymer solution), hydrogen gas Was released. This reaction solution was put into a solvent removal apparatus, and the solvent was removed so as to be 500 ppm or less to obtain a pellet-shaped hydrogenated polymer (hereinafter referred to as “resin A1”). The hydrogenation rate measured using ¹ H-NMR of the resin A was 99.9%.
About resin A1, when the number average molecular weight (Mn) and weight average molecular weight (Mw) in terms of polystyrene were measured by gel permeation chromatography (GPC, solvent: tetrahydrofuran), the number average molecular weight (Mn) was 20,800, The weight average molecular weight (Mw) was 62,000, and the molecular weight distribution (Mw / Mn) was 3.00. In addition, the glass transition temperature (Tg) of Resin A was 130 ° C., and the saturated water absorption rate at 23 ° C. was 0.3%. Moreover, it was 0.51 dl / g when intrinsic viscosity ((eta) _inh ) was measured in 30 degreeC chloroform.

<Preparation Example 1>
The reaction vessel was charged with 250 parts of distilled water, and after adding 90 parts of butyl acrylate, 8 parts of 2-hydroxyethyl methacrylate, 2 parts of divinylbenzene, and 0.1 part of potassium oleate, The system was dispersed by stirring with a stirring blade made of polytetrafluoroethylene. Thereafter, the inside of the reaction vessel was purged with nitrogen, and then the temperature of the system was raised to 50 ° C., and 0.2 part of potassium persulfate was added to initiate polymerization. After 2 hours from the start of the polymerization, 0.1 part of potassium persulfate was further added to the polymerization reaction system, and then the system was heated to 80 ° C. and the polymerization reaction was continued for 1 hour to obtain a polymer dispersion. Got.
Next, by using an evaporator, the aqueous dispersion (adhesive having a polar group) composed of an aqueous dispersion of an acrylic ester polymer is obtained by concentrating the polymer dispersion until the solid content becomes 70%. Obtained.
The acrylic ester polymer constituting the aqueous adhesive (hereinafter referred to as “aqueous adhesive A”) thus obtained is subjected to gel permeation chromatography (GPC, solvent: tetrahydrofuran) and converted into polystyrene. When the average molecular weight (Mn) and the weight average molecular weight (Mw) were measured, the number average molecular weight (Mn) was 69,000 and the weight average molecular weight (Mw) was 135,000.
Moreover, about the water-based adhesive A, when intrinsic viscosity ((eta) _inh ) was measured in 30 degreeC chloroform, it was 1.2 dl / g.

[Example 1]
Resin A was extruded downstream with a gear pump using a twin screw extruder (manufactured by Toshiba Machine Co., Ltd .; TEM-48), and a metal fiber sintered filter made by Nippon Seisen with a nominal aperture of 10 μm was used. Then, melt filtration was performed, and a coat hanger type T die (650 mm width) was used to extrude into a film at 280 ° C. with a gap of 0.5 mm at the exit of the T die.
The extruded film is sandwiched between a cooling roll whose surface roughness Rs has a surface roughness Rs maximum value Rmax (μm) of 0.1 and a metal belt having a thickness of 0.3 mm. Transcribed to.
Then, it peeled using the peeling roll whose surface roughness Rs maximum value Rmax (micrometer) which coat | covered the aluminum oxide was 0.1. At this time, the rotational speed of both rolls was adjusted so that the stress at the time of peeling was 23 kgf / cm ² while confirming with a temperature sensor that the temperature of the resin would be Tg + 3 ° C. by adjusting the roll temperature.
Thereafter, the resin film peeled from the mirror roll is bonded to a polyethylene protective film having a thickness of 50 μm, and a resin film having a thickness of 100 μm and a length of 2000 m (hereinafter also referred to as “resin film (a-1)”). Obtained. Table 1 shows the results of various evaluations on the resin film (a-1). Moreover, the total light transmittance of the obtained resin film (a-1) was 93%.

[Example 2]
Using the resin film (a-1) obtained in Example 1, the resin film (a-2) was obtained by stretching 1.5 times using a tenter-type lateral stretching machine at Tg + 10 ° C. Various evaluation results are summarized in Table 1. The total light transmittance of the resin film (a-2) was 93%.
[Example 3]
A polyvinyl alcohol film having a thickness of 50 μm was uniaxially stretched up to 4 times in about 5 minutes while being immersed in a 40 ° C. bath composed of 5 g of iodine, 250 g of potassium iodide, 10 g of boric acid, and 1000 g of water to obtain a polarizing film. The resin film (a-1) produced in Example 1 was used for the surface of this polarizing film, and the resin film (a-1) produced in Example 1 was used for the surface of this polarizing film. -2) was bonded to the other surface of the polarizing film to obtain a polarizing plate (1) having a transmittance of 40% and a polarization degree of 99.9%. This polarizing plate (1) was subjected to a durability test for 500 hours under the conditions of 80 ° C. and 90% relative humidity, and when the appearance change was visually observed, no appearance abnormality such as whitening or blistering was observed. Further, the degree of polarization was also confirmed to have a good degree of durability since the degree of polarization was maintained at 95% or more with respect to the initial value. In addition, when the polarizing plate (1) was placed in a crossed Nicols state and bonded to a cell of a VA type liquid crystal television to confirm the visibility, a good viewing angle compensation effect could be confirmed without unevenness. .

[Comparative Example 1]
In Example 1, a resin film (b-1) was obtained in the same manner as in Example 1 except that it was carried out without adjusting the rotation speeds of the cooling roll and the peeling roll. Various evaluation results of the resin film (b-1) are summarized in Table 1. Moreover, the total light transmittance of the resin film (b-1) was 92%.
[Comparative Example 2]
Except having used the resin film (b-1), it extended | stretched similarly to Example 2 and obtained the resin film (b-2). Various evaluation results of the resin film (b-2) are shown in Table 1. The total light transmittance of the resin film (b-2) was 92%.
[Comparative Example 3]
Resin film (b-1) was used instead of resin film (a-1), and resin film (b-2) was used instead of resin film (a-2). Thus, a polarizing plate (2) having a transmittance of 40% and a polarization degree of 99.9% was obtained. When this polarizing plate (2) was subjected to a durability test for 500 hours under the conditions of 80 ° C. and 90% relative humidity, and the appearance change was visually observed, none of the appearance abnormalities such as whitening or blistering were observed. Further, the degree of polarization was also confirmed to have a good degree of durability since the degree of polarization was maintained at 95% or more with respect to the initial value. However, when the polarizing plate (2) is placed in a crossed Nicols state and attached to a VA type liquid crystal television to confirm the visibility, light leakage is confirmed as a whole and partial strong light leakage is recognized. The viewing angle compensation effect was insufficient.

Claims (9)

In the process of manufacturing an optical film, a molten cyclic olefin-based resin is extruded from a die and pressed onto a base material to form a film, and the film is peeled off from the base material and wound into a roll. In any of the steps until winding up in a roll shape, the cyclic olefin resin has a step of applying a stress of 1 to 30 kgf / cm ² at a temperature of Tg−30 ° C. to Tg + 20 ° C. Manufacturing method of optical film. The film is peeled from the substrate at a stress of 1 to 30 kgf / cm ² at a temperature of Tg-30 ° C to Tg + 20 ° C of the cyclic olefin resin when the film is peeled from the substrate. Manufacturing method of the optical film. A cyclic olefin-based resin is dissolved or dispersed in an organic solvent and cast onto a base material, a part of the organic solvent is removed to form a film-like composition, and the film-like composition is peeled off from the base material. In the manufacturing process of the optical film that removes the organic solvent and winds up into a roll shape, the apparent Tg of the film-shaped composition in any step from peeling the film-shaped composition from the substrate and winding up into a roll shape A method for producing an optical film, comprising a step of applying a stress of 1 to 30 kgf / cm ² at a temperature of −30 ° C. to Tg + 20 ° C. (However, the apparent Tg of the film-like composition means Tg measured by a DSC curve obtained by measuring the film-like composition under a temperature rising condition of 20 ° C./min.) When the film-like composition is peeled from the substrate, the film-like composition is peeled from the substrate with a stress of 1 to 30 kgf / cm ² under the apparent temperature of Tg−30 ° C. to Tg + 20 ° C. The method for producing an optical film according to claim 3. (However, the apparent Tg of the film-like composition means Tg measured by a DSC curve obtained by measuring the film-like composition under a temperature rising condition of 20 ° C./min.) Made of cyclic olefin resin,
When the refractive index in the direction showing the maximum refractive index in the film plane at a light wavelength of 550 nm is nx, the refractive index in the direction perpendicular to nx in the film plane is ny, and the film thickness is d [nm],
A phase difference R0 (550) [nm] = (nx−ny) × d in the film plane is 20 nm or more and 300 nm or less, a variation in R0 is within ± 10%, and a direction showing the maximum refractive index in the film plane An optical film, wherein the maximum value of the angle formed by the film longitudinal direction is 0 ° to 10 °. The optical film according to claim 5, wherein the cyclic olefin-based resin is a resin obtained by polymerizing or copolymerizing at least one compound represented by the following formula (1):

(In Formula (1), R < ¹ > -R < ⁴ > is a hydrogen atom, a halogen atom, a C1-C30 hydrocarbon group, or another monovalent organic group, and may be the same or different. Further, any two of R ^{1 to} R ⁴ may be bonded to each other to form a monocyclic or polycyclic structure, m is 0 or a positive integer, and p is 0 or a positive integer. .)   A method for producing a stretched film, wherein the optical film according to claim 5 is stretched in the film width direction.   A method for producing a stretched film, wherein the optical film according to claim 5 is stretched in the longitudinal direction of the film. The manufacturing method of the stretched film characterized by extending | stretching the obtained optical film to a film width direction following the method of Claims 1 thru | or 4.