JP2008137175A - Manufacturing method of optical film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing an optical film having no repeated dents and excellent surface uniformity.
A method for producing an optical film, comprising melting a cyclic olefin-based resin, extruding from a die, and pressing into a cooling roll by a method satisfying the following conditions (1) to (3): I will provide a.
(1) The material of the surface of the cooling roll is a ceramic selected from aluminum oxide, tungsten carbide, and chromium oxide.
(2) The surface roughness of the cooling roll surface is 0.1 to 0.5 s.
(3) The pressure bonding of the molten resin to the cooling roll is performed by electrostatically applying to the film at a voltage of 2 to 8 kV for 0.5 to 5 seconds.
[Selection figure] None

Description

  The present invention relates to a method for producing an optical film made of a cyclic olefin resin.

Cyclic olefin-based resins are excellent in transparency, heat resistance, moisture resistance, and the like, and are therefore suitably used for optical film applications. Usually, a film made of a cyclic olefin resin is formed by a solution casting method (solution casting method) or a melt extrusion method, and the melt extrusion method is particularly preferably used from the viewpoint of productivity.
However, even with liquid crystal panels that have been used perfectly, there are cases where the above-mentioned increases in size and image quality cannot be fully achieved when conventional optical films and polarizing plates are used. There was a problem to do. In particular, in addition to leakage of light in the black display state, color change (color shift) and uniformity of these characteristics in large displays are becoming problems.
In particular, when a film is formed by melt extrusion, the film extruded from the die is pressed onto a cooling roll to form a film. At this time, due to unevenness or scratches on the surface of the cooling roll, the optical film has a period. Scratches (repeated dents) may occur. When a polarizing plate is manufactured using such an optical film, the uniformity of optical characteristics is impaired, and thus the yield of a polarizing plate used for, for example, a large-sized television is deteriorated.
JP-A-2005-99097 JP 2004-258188 A

  An object of the present invention is to provide a method for producing an optical film having no repeated dents and excellent surface uniformity.

The present invention is a method for producing an optical film, comprising melting a cyclic olefin-based resin, extruding it from a die, and pressing it onto a cooling roll by a method that satisfies the following conditions (1) to (3): About.
(1) The material of the surface of the cooling roll is a ceramic selected from aluminum oxide, tungsten carbide, and chromium oxide.
(2) The surface roughness of the cooling roll surface is 0.1 to 0.5 s.
(3) The pressure bonding of the molten resin to the cooling roll is performed by electrostatically applying to the film at a voltage of 2 to 8 kV for 0.5 to 5 seconds.
Next, this invention relates to the manufacturing method of an optical film characterized by further extending | stretching.

  According to the present invention, it is possible to provide a method for producing an optical film having no repeated dents and excellent surface uniformity. The retardation film obtained by stretching the optical film is stable with no variation in phase difference or optical axis, and large-screen liquid crystal displays using this have high performance without distortion or unevenness on the entire surface. Can be achieved.

<Cyclic olefin resin>
Examples of the cyclic olefin resin used in the method for producing an optical film of the present invention include a resin having a structural unit derived from a compound represented by the following general formula (1) (hereinafter also referred to as “specific monomer”). be able to.

(In General 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. 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. is there.)

Examples of the cyclic olefin resin include the following (co) polymers.
(1) A ring-opening polymer of a specific monomer represented by the general formula (1).
(2) A ring-opening copolymer of the specific monomer represented by the general formula (1) and a copolymerizable monomer.
(3) A hydrogenated (co) polymer of the ring-opening (co) polymer of (1) or (2) above.
(4) A (co) polymer obtained by cyclizing the ring-opening (co) polymer of (1) or (2) above by a Friedel-Craft reaction and then hydrogenating it.
(5) A saturated copolymer of the specific monomer represented by the general formula (1) and an unsaturated double bond-containing compound.
(6) Addition type (co) of one or more monomers selected from the specific monomer represented by the general formula (1), the vinyl-based cyclic hydrocarbon-based monomer, and the cyclopentadiene-based monomer Polymers and their hydrogenated (co) polymers.
(7) An alternating copolymer of the specific monomer represented by the general formula (1) and an acrylate.

  Of these (co) polymers, the hydrogenated (co) polymer of the ring-opening (co) polymer of the above (3) is particularly preferably used from the viewpoint of transparency, light resistance, moldability and the like. The structure of the polymer has a structural unit represented by the following general formula (2).

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

<Specific monomer>
Specific examples of the specific monomer include the following compounds, but the present invention is not limited to these specific examples.
Bicyclo [2.2.1] hept-2-ene,
Tricyclo [4.3.0.1 ^2,5 ] -8-decene,
Tricyclo [4.4.0.1 ^2,5 ] -3-undecene,
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,
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-ethoxycarbonyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-n-propoxycarbonyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-isopropoxycarbonyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-n-butoxycarbonyltetracyclo [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-ethoxycarbonyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-methyl-8-n-propoxycarbonyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-methyl-8-isopropoxycarbonyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-methyl-8-n-butoxycarbonyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
5-ethylidenebicyclo [2.2.1] hept-2-ene,
8-ethylidenetetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
5-phenylbicyclo [2.2.1] hept-2-ene,
8-phenyltetracyclo [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-fluorotetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-fluoromethyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-difluoromethyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-trifluoromethyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-pentafluoroethyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8,8-difluorotetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8,9-difluorotetracyclo [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-trifluoromethyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8,8,9-trifluorotetracyclo [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-tetrafluorotetracyclo [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-trifluoromethyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8,8,9-trifluoro-9-trifluoromethoxytetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8,8,9-trifluoro-9-pentafluoropropoxytetracyclo [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-heptafluoroiso-propyl-9-trifluoromethyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-chloro-8,9,9-trifluorotetracyclo [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-trifluoroethoxycarbonyl) tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-methyl-8- (2,2,2-trifluoroethoxycarbonyl) tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene.
These can be used alone or in combination of two or more.

Among the specific monomers, in the general formula (1), R ¹ and R ³ are each a hydrogen atom or a hydrocarbon group having 1 to 10, more preferably 1 to 4, particularly preferably 1 to 2 carbon atoms. 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 having a polarity other than a hydrogen atom and a hydrocarbon group, and m is 0 An integer of ˜3, p is an integer of 0 to 3, more preferably m + p = 0 to 4, more preferably 0 to 2, particularly preferably m = 1 and p = 0. The specific monomer in which m = 1 and p = 0 is preferable in that the cyclic olefin resin obtained has a high glass transition temperature and excellent mechanical strength.
Examples of the polar group of the specific monomer include a carboxyl group, a hydroxyl group, an alkoxycarbonyl group, an allyloxycarbonyl group, an amino group, an amide group, and a cyano group. These polar groups are connected via a linking group such as a methylene group. May be combined. In addition, a hydrocarbon group in which a divalent organic group having a polarity such as a carbonyl group, an ether group, a silyl ether group, a thioether group, or an imino group is bonded as a linking group can also be exemplified. Among these, a carboxyl group, a hydroxyl group, an alkoxycarbonyl group or an allyloxycarbonyl group is preferable, and an alkoxycarbonyl group or an allyloxycarbonyl group is particularly preferable.

Furthermore, 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 is a material in which the obtained cyclic olefin-based resin has a high glass transition temperature, a low hygroscopic property, and various materials. It is preferable at the point from which it has the outstanding adhesiveness. In the formula relating to 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, and preferably an alkyl group. In addition, n is usually 0 to 5, but the smaller the value of n, the higher the glass transition temperature of the resulting cyclic olefin resin, which is preferable, and the specific monomer having n of 0 is It is preferable in that the synthesis is easy.

In the general formula (1), R ¹ or R ³ is preferably an alkyl group, more preferably an alkyl group having 1 to 4 carbon atoms, more preferably an alkyl group having 1 to 2 carbon atoms, particularly a methyl group. In particular, it is preferable that the alkyl group is bonded to the same carbon atom as the carbon atom to which the specific polar group represented by the above formula — (CH ₂ ) _n COOR is bonded. This is preferable in that the hygroscopicity can be lowered.

<Copolymerizable monomer>
Specific examples of the copolymerizable monomer include cycloolefins such as cyclobutene, cyclopentene, cycloheptene, cyclooctene, and dicyclopentadiene.
The number of carbon atoms of the cycloolefin is preferably 4-20, and more preferably 5-12. These can be used alone or in combination of two or more.
A preferred use range of the specific monomer / copolymerizable monomer is 100/0 to 50/50, more preferably 100/0 to 60/40, in weight ratio.

<Ring-opening polymerization catalyst>
In the present invention, (1) a ring-opening polymer of a specific monomer, and (2) a ring-opening polymerization reaction for obtaining a ring-opening copolymer of a specific monomer and a copolymerizable monomer are metathesis It is carried out in the presence of a catalyst.
This metathesis catalyst comprises (a) at least one selected from W, Mo and Re compounds, (b) Deming periodic table group IA elements (for example, Li, Na, K, etc.), IIA group elements (for example, , Mg, Ca, etc.), Group IIB elements (eg, Zn, Cd, Hg, etc.), Group IIIA elements (eg, B, Al, etc.), Group IVA elements (eg, Si, Sn, Pb, etc.), or Group IVB A catalyst comprising a combination of at least one element selected from compounds having elements (for example, Ti, Zr, etc.) and having at least one element-carbon bond or the element-hydrogen bond. In this case, in order to increase the activity of the catalyst, an additive (c) described later may be added.

As typical examples of W, Mo or Re compounds suitable as the component (a), WCl ₆ , MoCl ₆ , ReOCl _{3 and the} like are disclosed in JP-A-1-132626, page 8, lower left column, line 6 to page 8, upper right. The compounds described in column 17th line can be mentioned.
(B) Specific examples of the _{component, 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, the compounds described in JP-A-1-132626, page 8, upper right column, line 18 to page 8, lower right column, line 3 can be exemplified.
As typical examples of the component (c) which is an additive, alcohols, aldehydes, ketones, amines and the like can be suitably used, but further, JP-A-1-132626, page 8, lower right column, The compounds shown in line 16 to page 9, upper left column, line 17 can be used.

The amount of the metathesis catalyst used is a range in which “(a) component: specific monomer” is usually 1: 500 to 1: 50,000 in terms of the molar ratio of the component (a) to the specific monomer. The range is preferably 1: 1,000 to 1: 10,000.
The ratio of the component (a) to the component (b) is such that (a) :( b) is 1: 1 to 1:50, preferably 1: 2 to 1:30 in terms of metal atomic ratio.
The ratio of the component (a) to the component (c) is such that the molar ratio (c) :( a) is in the range of 0.005: 1 to 15: 1, preferably 0.05: 1 to 7: 1. The

<Solvent for polymerization reaction>
Examples of the solvent used in the ring-opening polymerization reaction (solvent constituting the molecular weight modifier solution, solvent for the specific monomer and / or metathesis catalyst) include alkanes such as pentane, hexane, heptane, octane, nonane, decane, Cycloalkanes such as cyclohexane, cycloheptane, cyclooctane, decalin, norbornane, aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, cumene, chlorobutane, bromohexane, methylene chloride, dichloroethane, hexamethylene dibromide, chlorobenzene, Compounds such as halogenated alkanes and aryl halides such as chloroform and tetrachloroethylene, saturated carbohydrates such as ethyl acetate, n-butyl acetate, iso-butyl acetate, methyl propionate, and dimethoxyethane Esters, dibutyl ether, tetrahydrofuran, and the like can be illustrated ethers such as dimethoxyethane, it can be used singly or in combination. Of these, aromatic hydrocarbons are preferred.
As the amount of the solvent used, “solvent: specific monomer (weight ratio)” is usually in an amount of 1: 1 to 10: 1, preferably in an amount of 1: 1 to 5: 1. The

<Molecular weight regulator>
The molecular weight of the resulting ring-opening (co) polymer can be adjusted by the polymerization temperature, the type of catalyst, and the type of solvent. In the present invention, the molecular weight is adjusted by allowing the molecular weight regulator to coexist in the reaction system. To do.
Here, suitable molecular weight regulators include, for example, α-olefins such as ethylene, propene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, and the like. Styrene can be mentioned, and among these, 1-butene and 1-hexene are particularly preferable.
These molecular weight regulators can be used alone or in admixture of two or more.
The amount of the molecular weight regulator used is 0.005 to 0.6 mol, preferably 0.02 to 0.5 mol, per 1 mol of the specific monomer subjected to the ring-opening polymerization reaction.

  (2) In order to obtain a ring-opening copolymer, a specific monomer and a copolymerizable monomer may be subjected to ring-opening copolymerization in the ring-opening polymerization step, and further, polybutadiene, polyisoprene, etc. In the presence of unsaturated hydrocarbon polymers such as conjugated diene compounds, styrene-butadiene copolymers, ethylene-nonconjugated diene copolymers, polynorbornene and the like containing two or more carbon-carbon double bonds in the main chain. The specific monomer may be subjected to ring-opening polymerization.

Although the ring-opening (co) polymer obtained as described above can be used as it is, (3) the hydrogenated (co) polymer obtained by further hydrogenation is a resin having high impact resistance. It is useful as a raw material.
<Hydrogenation catalyst>
In the hydrogenation reaction, a hydrogenation catalyst is added to a usual method, that is, a solution of a ring-opening polymer, and hydrogen gas at normal pressure to 300 atm, preferably 3 to 200 atm, is added thereto at 0 to 200 ° C., preferably 20 It is carried out by operating at ~ 180 ° C.
As a hydrogenation catalyst, what is used for the hydrogenation reaction of a normal olefinic compound can be used. Examples of the hydrogenation catalyst include a heterogeneous catalyst and a homogeneous catalyst.

  Examples of the heterogeneous catalyst include a solid catalyst in which a noble metal catalyst material such as palladium, platinum, nickel, rhodium, and ruthenium is supported on a carrier such as carbon, silica, alumina, and titania. In addition, homogeneous catalysts include nickel naphthenate / triethylaluminum, nickel acetylacetonate / triethylaluminum, cobalt octenoate / n-butyllithium, titanocene dichloride / diethylaluminum monochloride, rhodium acetate, chlorotris (triphenylphosphine) rhodium. Dichlorotris (triphenylphosphine) ruthenium, chlorohydrocarbonyltris (triphenylphosphine) ruthenium, dichlorocarbonyltris (triphenylphosphine) ruthenium, and the like. The form of the catalyst may be powder or granular.

These hydrogenation catalysts are used in such a ratio that the ring-opening (co) polymer: hydrogenation catalyst (weight ratio) is 1: 1 × 10 ⁻⁶ to 1: 2.
As described above, the hydrogenated (co) polymer obtained by hydrogenation has excellent thermal stability, and its characteristics deteriorate due to heating during molding and use as a product. There is no. Here, the hydrogenation rate is usually 50% or more, preferably 70% or more, more preferably 90% or more, and particularly preferably 99% or more.

The hydrogenation rate of the hydrogenated (co) polymer is 50% or more, preferably 90% or more, more preferably 98% or more, most preferably 99% or more, as measured by 500 MHz and ¹ H-NMR. is there. The higher the hydrogenation rate, the better the stability to heat and light, and when used as the wave plate of the present invention, stable characteristics can be obtained over a long period of time.
The hydrogenated (co) polymer used as the cyclic olefin resin preferably has a gel content contained in the hydrogenated (co) polymer of 5% by weight or less, more preferably 1% by weight or less. It is particularly preferred that

As the cyclic olefin-based resin, (4) a (co) polymer obtained by cyclizing the ring-opened (co) polymer of the above (1) or (2) by Friedel-Craft reaction and then hydrogenating it can also be used.
<Cyclization by Friedel-Craft reaction>
The method for cyclizing the ring-opened (co) polymer of (1) or (2) by Friedel-Craft reaction is not particularly limited, but the acidic compound described in JP-A-50-154399 is used. Any known method can be employed. Specifically, Lewis acids such as AlCl ₃ , BF ₃ , FeCl ₃ , Al ₂ O ₃ , HCl, CH ₂ ClCOOH, zeolite, activated clay, and Bronsted acid are used as the acidic compound.
The cyclized ring-opening (co) polymer can be hydrogenated in the same manner as the ring-opening (co) polymer (1) or (2).

Further, as the cyclic olefin resin, (5) a saturated copolymer of the specific monomer and the unsaturated double bond-containing compound can also be used.
<Unsaturated double bond-containing compound>
As an unsaturated double bond containing compound, ethylene, propylene, butene etc., Preferably it is C2-C12, More preferably, C2-C8 olefin type compound can be mentioned.
The preferred use range of the specific monomer / unsaturated double bond-containing compound is 90/10 to 40/60, more preferably 85/15 to 50/50, in weight ratio.

In the present invention, in order to obtain a saturated copolymer of (5) a specific monomer and an unsaturated double bond-containing compound, a usual addition polymerization method can be used.
<Addition polymerization catalyst>
As the catalyst for synthesizing the (5) saturated copolymer, at least one selected from a titanium compound, a zirconium compound and a vanadium compound and an organoaluminum compound as a promoter are used.
Here, examples of the titanium compound include titanium tetrachloride and titanium trichloride, and examples of the zirconium compound include bis (cyclopentadienyl) zirconium chloride and bis (cyclopentadienyl) zirconium dichloride.

Moreover, as the vanadium compound, the general formula VO _(OR) a _{X b} or V _(OR) c _{X d,}
[Wherein R is a hydrocarbon group, X is a halogen atom, and 0 ≦ a ≦ 3, 0 ≦ b ≦ 3, 2 ≦ (a + b) ≦ 3, 0 ≦ c ≦ 4, 0 ≦ d ≦ 4, 3, ≦ (c + d) ≦ 4. ]
Or an electron-donating adduct of these compounds.
Examples of the electron donor include alcohols, phenols, ketones, aldehydes, carboxylic acids, esters of organic acids or inorganic acids, ethers, acid amides, acid anhydrides, oxygen-containing electron donors such as alkoxysilanes, ammonia, amines, Examples thereof include nitrogen-containing electron donors such as nitrile and isocyanate.

Furthermore, as the organoaluminum compound as the promoter, at least one selected from those having at least one aluminum-carbon bond or aluminum-hydrogen bond is used.
In the above, for example, when the vanadium compound is used, the ratio of the vanadium compound to the organoaluminum compound is such that the ratio of aluminum atom to vanadium atom (Al / V) is 2 or more, preferably 2 to 50, particularly preferably 3 to 20. Range.

  As the solvent for the polymerization reaction used for the addition polymerization, the same solvent as that used for the ring-opening polymerization reaction can be used. Moreover, adjustment of the molecular weight of the (5) saturated copolymer obtained is normally performed using hydrogen.

Furthermore, as the cyclic olefin-based resin, (6) an addition copolymer of the above specific monomer and one or more monomers selected from the vinyl-based cyclic hydrocarbon monomer or the cyclopentadiene monomer And hydrogenated copolymers thereof can also be used.
<Vinyl cyclic hydrocarbon monomer>
Examples of the vinyl cyclic hydrocarbon monomer include vinyl cyclopentene monomers such as 4-vinylcyclopentene and 2-methyl-4-isopropenylcyclopentene, 4-vinylcyclopentane, 4-isopropenylcyclopentane and the like. Vinylated 5-membered hydrocarbon monomers such as vinylcyclopentane monomers, 4-vinylcyclohexene, 4-isopropenylcyclohexene, 1-methyl-4-isopropenylcyclohexene, 2-methyl-4-vinyl Vinylcyclohexene monomers such as cyclohexene and 2-methyl-4-isopropenylcyclohexene, vinylcyclohexane monomers such as 4-vinylcyclohexane and 2-methyl-4-isopropenylcyclohexane, styrene, α-methylstyrene, 2-methylstyrene, 3- Styrenic monomers such as styrene styrene, 4-methylstyrene, 1-vinylnaphthalene, 2-vinylnaphthalene, 4-phenylstyrene, p-methoxystyrene, d-terpene, 1-terpene, diterpene, d-limonene, 1- Terpene monomers such as limonene and dipentene, vinylcycloheptene monomers such as 4-vinylcycloheptene and 4-isopropenylcycloheptene, 4-vinylcycloheptane, 4-isopropenylcycloheptane, etc. And vinyl cycloheptane monomers. Styrene and α-methylstyrene are preferable. These can be used alone or in combination of two or more.

<Cyclopentadiene monomer>
Examples of the cyclopentadiene monomer used as the monomer of the addition copolymer (6) of the present invention include, for example, cyclopentadiene, 1-methylcyclopentadiene, 2-methylcyclopentadiene, 2-ethylcyclopentadiene, Examples include 5-methylcyclopentadiene and 5,5-methylcyclopentadiene. Cyclopentadiene is preferred. These can be used alone or in combination of two or more.

The addition type (co) polymer of at least one monomer selected from the above specific monomer, vinyl cyclic hydrocarbon monomer and cyclopentadiene monomer is the above (5) specific monomer. It can be obtained by the same addition polymerization method as the saturated copolymer of the unsaturated double bond-containing compound.
The hydrogenated (co) polymer of the addition type (co) polymer can be obtained by the same hydrogenation method as the hydrogenated (co) polymer of the above (3) ring-opening (co) polymer. .

Further, as the cyclic olefin resin, (7) an alternating copolymer of the specific monomer and acrylate can also be used.
<Acrylate>
(7) Examples of the acrylate used for the production of the alternating copolymer of the specific monomer and the acrylate include, for example, straight chain having 1 to 20 carbon atoms such as methyl acrylate, 2-ethylhexyl acrylate, and cyclohexyl acrylate, C2-C20 heterocyclic group-containing acrylate such as branched or cyclic alkyl acrylate, glycidyl acrylate, 2-tetrahydrofurfuryl acrylate, C6-C20 aromatic ring group-containing acrylate such as benzyl acrylate, Examples thereof include acrylates having a polycyclic structure having 7 to 30 carbon atoms such as boronyl acrylate and dicyclopentanyl acrylate.

In the present invention, (7) In order to obtain an alternating copolymer of the specific monomer and acrylate, when the total of the specific monomer and acrylate is 100 mol in the presence of Lewis acid, The specific monomer is 30 to 70 mol, the acrylate is 70 to 30 mol, preferably the specific monomer is 40 to 60 mol, and the acrylate is 60 to 40 mol, particularly preferably the specific monomer. The body undergoes radical polymerization at a rate of 45 to 55 mol and acrylate at a rate of 55 to 45 mol.
(7) The amount of Lewis acid used to obtain the alternating copolymer of the specific monomer and acrylate is 0.001 to 1 mol per 100 mol of acrylate. Also, known organic peroxides or azobis radical polymerization initiators that generate free radicals can be used, and the polymerization reaction temperature is usually -20 ° C to 80 ° C, preferably 5 ° C to 60 ° C. . Moreover, the same solvent as used for the ring-opening polymerization reaction can be used as the solvent for the polymerization reaction.
The “alternate copolymer” as used herein refers to a structure in which the structural unit derived from the specific monomer is not adjacent, that is, the structural unit derived from the acrylate is always adjacent to the structural unit derived from the specific monomer. It means a copolymer having a structure as a unit, and does not deny a structure in which structural units derived from acrylate are adjacent to each other.

The preferred molecular weight of the cyclic olefin resin used in the present invention is 0.2 to 5 dl / g, more preferably 0.3 to 3 dl / g, particularly preferably 0.4 to 1.5 dl in terms of intrinsic viscosity [η] _inh. The polystyrene-reduced number average molecular weight (Mn) measured by gel permeation chromatography (GPC) after dissolving in tetrahydrofuran is 8,000 to 100,000, more preferably 10,000 to 80,000, Particularly preferred is 12,000 to 50,000, and the weight average molecular weight (Mw) is 20,000 to 300,000, more preferably 30,000 to 250,000, particularly preferably 40,000 to 200,000. A range is preferred.
Inherent viscosity [η] _inh , number average molecular weight and weight average molecular weight are in the above ranges, so that the heat resistance, water resistance, chemical resistance, mechanical properties of the cyclic olefin resin and molding as the optical film of the present invention Workability is improved.

  As glass transition temperature (Tg) of cyclic olefin resin used for this invention, it is 110 degreeC or more normally, Preferably it is 110-350 degreeC, More preferably, it is 120-250 degreeC, Most preferably, it is 120-200 degreeC. When Tg is less than 110 ° C., it is not preferable because it is deformed by use under a high temperature condition or by secondary processing such as coating or printing. On the other hand, when Tg exceeds 350 ° C., the molding process becomes difficult, and the possibility that the resin deteriorates due to heat during the molding process increases.

  The above cyclic olefin-based resins are not limited to the specific hydrocarbon-based resins described in, for example, JP-A-9-221577 and JP-A-10-287732 or publicly known, as long as the effects of the present invention are not impaired. These thermoplastic resins, thermoplastic elastomers, rubber polymers, organic fine particles, inorganic fine particles and the like may be blended.

  In addition, additives such as known antioxidants and ultraviolet absorbers are added to the cyclic olefin resin used in the present invention in order to improve heat resistance and light resistance within a range not impairing the effects of the present invention. can do. For example, at least one compound selected from the group consisting of a phenol compound, a thiol compound, a sulfide compound, a disulfide compound, and a phosphorus compound is 0.01 to 10 weights with respect to 100 parts by weight of the cyclic olefin resin. By adding a part, the heat deterioration resistance can be improved. In addition, when the cyclic olefin-based resin according to the present invention is formed into a film or the like by melt extrusion, an antioxidant is added to prevent the resin from being thermally deteriorated due to a heat history at the time of melt extrusion. Also good. As the antioxidant, when a film obtained by melt extrusion is stretched, a glass of a cyclic olefin resin to be melt-extruded in order to prevent the retardation from being lowered or to minimize the degree of reduction. It is preferable to use a hindered phenol compound having a melting point in the temperature range of −30 ° C. to Tg + 130 ° C., preferably Tg−25 ° C. to Tg + 130 ° C., than the transition temperature (Tg).

<Method for producing optical film>
As a method for producing the optical film of the present invention, a melt extrusion method is used in which a cyclic olefin-based resin is melted, extruded from a die, and pressed into a cooling roll to form a film.
As a method of melting the cyclic olefin-based resin, a method of melting the resin by an extruder is preferable, and the molten resin is quantitatively supplied by a gear pump, and this is filtered through a metal filter or the like to remove impurities, and then is die-cast. A method of extruding while forming into a film shape is preferable.
As a method for cooling the film extruded from the die to form a sheet, for example, a first cooling roll is disposed below the discharge port of the die, and a second cooling roll is adjacent to the first cooling roll. The film manufacturing apparatus which is arrange | positioned, the 3rd cooling roll is arrange | positioned adjacent to the said 2nd cooling roll as needed, and the peeling roll is arrange | positioned in parallel with the said 3rd (or 2nd) cooling roll. Or the film manufacturing apparatus by which a cooling roll and a metal belt are arrange | positioned and the peeling roll is arrange | positioned in parallel with the said cooling roll is mentioned. In addition, the said metal belt is hold | maintained in the state in which tension | tensile_strength was acted by the two holding rolls provided so that the inner surface might be contact | connected. The resin discharged from the discharge port is pressure-bonded to the (first) cooling roll by electrostatic application at a voltage of 2 to 8 kV for 0.5 to 5 seconds. Thereafter, the sheet is sandwiched between the first cooling roll and the second cooling roll or between the cooling roll and the metal belt, transferred to the (first) cooling roll, cooled, and then peeled off. Is peeled to form a film. In addition, by using the charging electrode placed at the both ends of the discharged film so as to face the cooling roll below the discharge port of the die, the film is stuck to the cooling roll side, so that optical distortion is not given. It is also preferable to use a method for improving the surface property of the film or to stick both ends of the film using the ear height portion using a pressing roll.

  As the extruder, any of a single screw, a twin screw, a planetary type, a kneader and the like may be used, but a single screw extruder is preferably used. In addition, the screw shape of the extruder is bent type, subflight type, tip dull mage type, full flight type, etc., with large compression ratio, small one, slow compression with long compression part length, short compression Although a compression type etc. are mentioned, gel becomes easy to generate | occur | produce in resin by mixing of oxygen and shear heat_generation | fever inside an extruder. Since this gel causes point-like defects called fish eyes in the film and burns, it is preferable to have a flight shape / compression type that can suppress dissolution of oxygen and suppress shearing heat generation, and a preferable compression ratio is 1.5 to 4.5, particularly preferably 1.8 to 3.6. The gear pump used for measuring the resin may use either an internal lubrication type or an external lubrication type, but an external lubrication type is preferred.

  Examples of the filter used for filtering foreign substances include a leaf disc type, a candle filter type, a leaf type, and a screen mesh. Among them, the leaf disk type is most preferable for the purpose of reducing the residence time distribution of the resin, and the nominal opening means the opening of the filter is 20 μm or less, preferably 10 μm or less, more preferably 5 μm or less. It is. Most preferably, it is 3 μm or less. When the nominal opening is larger than 20 μm, it is difficult to remove gels and the like in addition to visible foreign substances, so that it is not preferable as a filter for making an optical film.

  As a die, it is essential to make the resin flow inside the die uniform, and in order to keep the film thickness uniform, it is essential that the pressure distribution inside the die near the die exit is constant in the width direction. It is. Manifold dies, fishtail dies, coat hanger dies, and the like can be used to satisfy such conditions, and among these, coat hanger dies are preferable. A bending lip type is preferable for adjusting the flow rate of the die. A die having a function of adjusting thickness by automatic control by a heat bolt method is particularly preferable. Installing a choke bar to adjust the flow rate or attaching a lip block to adjust the thickness creates a step in the mounting part, or traps air or the like in the gap of the mounting part. This is not preferable because it may cause generation or die line. The discharge port of the die is preferably coated with a carbide coating such as tungsten carbide. Examples of the material of the die include SCM steel and stainless steel such as SUS, but are not limited thereto. In addition, the surface is plated with chromium, nickel, titanium, etc., and the film such as TiN, TiAlN, TiC, CrN, DLC (diamond-like carbon) is formed by PVD (Physical Vapor Deposition) method, etc. Further, a ceramic sprayed one, a surface nitrided one, etc. can be used. Since such a die has high surface hardness and low friction with the resin, it is possible to prevent burnt dust and the like from being mixed into the transparent resin sheet obtained and to prevent the occurrence of die lines. It is preferable at the point which can do.

The cooling roll preferably has a heating means and a cooling means inside, and a material whose surface material is ceramic selected from aluminum oxide, tungsten carbide and chromium oxide is used. Of these, aluminum oxide is particularly preferable from the viewpoint of surface hardness and strength. When using a plurality of cooling rolls, it is necessary that at least one of the cooling rolls be made of the above ceramics, and in particular, the first cooling roll surface where the resin discharged from the die first contacts is made of the above ceramics. Preferably there is.
The said cooling roll is suitably obtained by coating the said ceramic on the said ceramic roll, for example, and methods, such as thermal spraying, sputtering, PVD, CVD, are mentioned as a coating method. Of these, a thermal spraying method that can uniformly coat a large area is particularly preferably used.
The thermal spraying thickness is 30 to 150 μm, preferably 35 to 120 μm, and more preferably 40 to 100 μm. When the coating thickness is less than 30 μm, the sprayed surface is likely to be scraped, and when the coating thickness exceeds 150 μm, cracking tends to occur due to the difference in shrinkage from the underlying metal.
The surface roughness of the cooling roll is 0.1 to 0.5 s, particularly preferably 0.2 to 0.4 S or less in terms of the maximum roughness Rs. When the surface roughness exceeds 0.5S, the roll surface becomes rough, and the unevenness is transferred to the film, which is not preferable. On the other hand, when the surface roughness is less than 0.1 s, the film is too close to the cooling roll, which is not preferable because the peel tension becomes too high and the residual phase difference becomes high.
Further, the cooling roll is a cyclic olefin resin film having a thickness of 40 to 140 μm at a temperature of Tg−15 ° C. to Tg of the resin and an electrostatic applied voltage of 2 to 8 kV for 0.5 to 5 seconds. The film peel strength after pressure bonding is preferably 5 kgf or less. When a cooling roll having such a peel strength is used, an effect of preventing cross marks orthogonal to the flow direction can be obtained.

  As a metal belt used for a single-sided belt type device or a sleeve type take-up device, it is preferable to use a seamless endless belt. As a material constituting the metal belt, stainless steel, nickel, or the like can be used. Moreover, it is preferable that the surface of the holding roll for holding the metal belt is coated with silicone rubber or other heat-resistant elastomer. The thickness of the metal belt is preferably 0.1 to 0.4 mm, and if it is less than 0.1 mm, the deflection is large and the belt may be damaged immediately, which is not preferable. On the other hand, if it is thicker than 0.4 mm, it is not preferable because it does not deform following the film during processing.

With the above apparatus, for example, a film is produced as follows.
Usually, before introducing the cyclic olefin-based resin into the extruder, water, gas (oxygen, etc.), residual solvent, etc. contained in the resin are removed in advance so as to have an appropriate Tg or less of the resin. Dry the resin at temperature.
As the dryer used for drying, an inert gas circulation dryer or a vacuum dryer is preferably used. It is also preferable to use a vacuum hopper that can absorb moisture in the hopper or seal the hopper with an inert gas such as nitrogen or argon, or can be kept in a reduced pressure state in order to suppress oxygen absorption.
The extruder cylinder is preferably sealed with an inert gas such as nitrogen or argon in order to prevent the resin from being oxidized during the melt extrusion and generating a gel or the like.
The cyclic olefin-based resin melted by the extruder is extruded in a sheet shape from the die discharge port toward the lower side which is the vertical direction. The temperature distribution at the die outlet is preferably controlled to be ± 1 ° C. or less, more preferably ± 0.5 ° C. or less in order to reduce the difference in melt viscosity of the resin.

The processing temperature of the resin, that is, the set temperature of the extruder and the die, is such that the molten resin having a uniform fluidity can be discharged from the die and the deterioration of the resin can be suppressed. It is preferable that it is Tg + 200 degrees C or less. Also, the shorter the distance from when the resin is discharged from the die discharge port to the contact with the cooling roll, the better the film thickness unevenness of the resulting film can be suppressed. This distance is preferably 100 mm or less. More preferably, it is 80 mm or less.

Thereafter, the extruded resin is clamped and cooled by the first cooling roll and the second cooling roll or metal belt. The resin transferred to the surface of the cooling roll is peeled off from the surface of the first roll by the peeling roll, passes through the surface of the second cooling roll, and is then cooled by the third cooling roll. Here, the surface temperature of the first cooling roll is preferably Tg-15 ° C to Tg of the resin, and more preferably Tg-12 to Tg-5 ° C.
Furthermore, as conditions at the time of film peeling, when setting it as peeling temperature _Tt (degreeC) and peeling stress _TF (MPa), the range of Tg-30 degreeC <= _Tt <= Tg + 5 degreeC, 0.01MPa < _TF <5MPa, respectively It is preferable that

  The total light transmittance of the optical film according to the present invention is preferably 90% or more, particularly preferably 95% or more.

<Extension process>
In the method for producing an optical film of the present invention, the optical film obtained as described above may be further stretched. Specific examples of the stretching method in this case include a known uniaxial stretching method or biaxial stretching method. That is, the horizontal uniaxial stretching method by the tenter method, the inter-roll compression stretching method, the longitudinal uniaxial stretching method using two sets of rolls with different circumferences, or the biaxial stretching method combining the horizontal uniaxial and the longitudinal uniaxial, inflation method The stretching method by, for example, can be used.
In the case of the uniaxial stretching method, the stretching speed is usually 1 to 5,000% / minute, preferably 50 to 1,000% / minute, more preferably 100 to 1,000% / minute, Preferably, it is 100 to 500% / min.
In the case of the biaxial stretching method, stretching may be performed in two directions at the same time, or the stretching may be performed in a direction different from the first stretching direction after uniaxial stretching. At this time, the intersecting angle of the two stretching axes for controlling the shape of the refractive index ellipsoid of the stretched film is not particularly limited because it is determined by desired characteristics, but is usually in the range of 120 to 60 degrees. It is. The stretching speed may be the same or different in each stretching direction, and is usually 1 to 5,000% / min, preferably 50 to 1,000% / min, more preferably Is from 100 to 1,000% / min, particularly preferably from 100 to 500% / min.

The stretching temperature is not particularly limited, but is usually Tg ± 30 ° C., preferably Tg ± 15 ° C., more preferably Tg−5 ° C. to Tg + 15 based on the glass transition temperature Tg of the resin of the present invention. It is in the range of ° C. Within the above range, it is possible to suppress the occurrence of phase difference unevenness, and it is preferable because the control of the refractive index ellipsoid becomes easy.
The draw ratio is not particularly limited because it is determined by desired properties, but is usually 1.01 to 10 times, preferably 1.03 to 5 times, and more preferably 1.03 to 3 times. When the draw ratio is 10 times or more, it may be difficult to control the phase difference.

  Although the stretched film may be cooled as it is, 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. As a result, a stable retardation film can be obtained with little change over time in the retardation of transmitted light.

The obtained stretched film has a haze value of 1% or less, preferably 0.8% or less when the thickness measured in accordance with ASTM D1003 is 3 mm. The average roughness Ra of the film is preferably 0.2 μm or less, more preferably 0.15 μm or less, and particularly preferably 0.1 μm or less.
The dimensional shrinkage ratio due to heating of the retardation film of the present invention is usually 10% or less, preferably 5% or less, more preferably 3% or less, particularly preferably 1 when heating at 100 ° C. for 500 hours. % Or less.

In the optical film obtained in the present invention, molecules are oriented by stretching to give a retardation to transmitted light. This retardation can be controlled by a stretching ratio, a stretching temperature, a film thickness, or the like. For example, when the thickness of the film before stretching is the same, the larger the stretching ratio, the larger the absolute value of the retardation of transmitted light tends to increase. Therefore, the desired retardation can be transmitted by changing the stretching ratio. A retardation film applied to light can be obtained. On the other hand, when the stretch ratio is the same, the greater the thickness of the film before stretching, the greater the absolute value of the retardation of transmitted light tends to increase. Therefore, by changing the thickness of the film before stretching, the desired value can be obtained. A retardation film that imparts retardation to transmitted light can be obtained. Further, in the above stretching processing temperature range, the lower the stretching temperature, the larger the absolute value of the retardation of the transmitted light tends to increase. Therefore, the retardation film gives the desired retardation to the transmitted light by changing the stretching temperature. Can be obtained.

  The thickness of the retardation film obtained by stretching as described above is usually 100 μm or less, preferably 100 to 20 μm, and more preferably 80 to 20 μm. By reducing the thickness, it is possible to greatly meet the demands for miniaturization and thinning required for products in the field where retardation films are used. Here, the thickness of the retardation film can be controlled by controlling the thickness of the optical film before stretching or by controlling the stretching ratio. For example, the thickness of the retardation film can be further reduced by thinning the optical film before stretching or by relatively increasing the stretching ratio.

<Use of optical film>
The optical film obtained by the production method of the present invention is a water-based adhesive composed of an aqueous solution mainly composed of PVA resin, a polar group-containing adhesive, photocuring property on at least one surface of a polarizer composed of a PVA-based film. A polarizing plate can be obtained by laminating using an adhesive or the like, heating or exposing as necessary, and pressing and adhering (laminating) the polarizer and the optical film.
In addition, a liquid crystal panel is manufactured by adhering (laminating) the liquid crystal display element and the polarizing plate to at least one surface of a liquid crystal display element in which liquid crystal is sandwiched between two glass substrates. can do.

Specific examples of the present invention will be described below, but the present invention is not limited to these examples. In the following, “parts” and “%” mean “parts by weight” and “% by weight” unless otherwise specified.
Further, in the following examples, various evaluations 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.
[Total light transmittance, haze]
Using a haze meter “HM-150 type” manufactured by Murakami Color Research Laboratory, total light transmittance and haze were measured.
[In-plane retardation of transmitted light (R0) and optical axis]
Using “KOBRA-21ADH” manufactured by Oji Scientific Instruments Co., Ltd., the in-plane retardation (R0) when light is incident on the film perpendicularly is at a wavelength of 550 nm, and the optical axis is directed downstream in the longitudinal direction of the film. Measured at 0 degree. In the ± 90 degrees direction, the optical axis is oriented in the TD direction (width direction).
[Transmissivity and degree of polarization of polarizing plate]
Using “RETS” manufactured by Otsuka Electronics Co., Ltd., the transmittance and polarization degree of the polarizing plate were measured. The measurement wavelength was 550 nm.
[Film thickness distribution]
It measured in the film longitudinal direction using the film thickness distribution measuring apparatus (MOCON).

Example 1
As the resin, a cyclic olefin-based resin (manufactured by JSR Corporation: trade name “ARTON D4531”, glass transition temperature 130 ° C.) is used and transported to a nitrogen circulation dryer (manufactured by Nissui Processing Co., Ltd .: model number NS-200). Then, dehumidification drying was performed at a drying temperature of 100 ° C. for 180 minutes in a nitrogen atmosphere. Then, it is guided to an extruder (GM Engineering Co., Ltd .: GM-90), melted at 260 ° C., fed in a fixed amount using a gear pump, removed foreign matter using a 5 μm leaf disc filter, and set to 250 ° C. The resin was extruded from a T-die having an opening width of 0.85 mm heated to 260 ° C. by the cast aluminum heater. The distance between the T-die outlet and the film crimping point in the first cooling roll is set to 65 mm, and the extruded resin is applied with a voltage of 5 kV at positions 50 mm from both ends in the film width direction for 1.5 seconds. Electrostatic pressure-bonded to the cooling roll. The cooling roll was grounded.
The film pressure-bonded to the first cooling roll is taken up at a film surface temperature of 128 ° C., and the taken-up film is pressure-bonded to a second cooling roll having a surface temperature of 125 ° C., and further, a third cooling roll having a surface temperature of 120 ° C., After pressure-bonding sequentially to a fourth cooling roll having a surface temperature of 115 ° C, the film surface temperature was 109 ° C and the film was peeled off with a tension of 4 kgf. The cooling rolls were all 250 mmφ, and the first and second cooling rolls were obtained by spraying a 75 μm thick aluminum oxide film on the roll surface. Further, the surface roughness of the first cooling roll was 0.3 s. Moreover, the peripheral speed of each cooling roll at this time was 7.60 m / min, 7.55 m / min, 7.50 m / min, and 7.47 m / min in this order. The film thickness of the obtained optical film (hereinafter also referred to as “film 1”) was 100 μm.
Moreover, when the optical axis of the obtained film 1 was confirmed, when the flow direction (longitudinal direction of the film) was 0 degree, it was -5 to 7 degrees, and the range where the optical axis was ± 5 degrees in the longitudinal direction was It was 85% with respect to the whole film width. Moreover, when the haze value of this film was measured, the haze value was 0.2%.

Example 2
In Example 1 above, when the film was transferred to the roll, it was installed so that both ends of the film were pressure-bonded to the roll using a press roll having a diameter of 100 mmφ, and the surface temperature of the press roll was 122 ° C. A film 2 was obtained in the same manner as in Example 1 except that the voltage applied to 4 kV was changed to 4 kV. When the optical axis of the film 2 was confirmed, the portion hitting the pressing roll was 80 to 90 degrees, and the absolute value of the optical axis inside the pressing rolls at both ends was 3 degrees or less. The range in which the optical axis is ± 5 ° in the longitudinal direction was 80% with respect to the entire film width. The haze value of the film 2 was 0.3%.

Comparative Example 1
A similar device was used using the same material as in Example 1 above. The distance between the outlets of the T die used for resin extrusion was 0.45 mm, and no voltage was applied to the film. A film was produced in the same manner as in Example 1 under other conditions. The obtained film was designated as film 3. The optical axis of the film 3 is 75 to 90 degrees in the distribution in the width direction, and the range in which the optical axis is ± 5 ° in the longitudinal direction is 82% with respect to the entire width of the film. Moreover, the haze value of the film 3 was 0.3%.

Comparative Example 2
In Example 1 above, the material of the cooling roll and the first peeling roll was changed to that of a hard chrome plating material without thermal spraying treatment of aluminum oxide on the surface, and the extruded film was cooled at the same temperature setting. The film could not be peeled uniformly from the cooling roll, and a film having a good appearance could not be obtained.

<Preparation Example 1>
It consists of 94.8 parts of butyl acrylate, 5 parts of acrylic acid, and 0.2 part of 2-hydroxyethyl methacrylate, and has a weight average molecular weight (Mw) of 1,200,000, and a ratio of weight average molecular weight to number average molecular weight (Mn) (Mw / Mn ) Toluene was added to an ethyl acetate solution of 3.9 acrylic polymer to dilute to obtain a 13% toluene solution of the above acrylic polymer, and 2.0 parts of an isocyanate cross-linking agent [Coronate L (manufactured by Nippon Polyurethane)] was added. Then, the stirred solution was applied onto the release film and dried in two steps of 60 ° C. × 5 minutes and 100 ° C. × 5 minutes so as not to foam, and then a light release type release film was further applied to the adhesive surface. The laminate was temporarily fixed, and a non-support film having an adhesive thickness (average value) of 25 μm after drying was produced.

Example 3
The film 1 obtained in Example 1 was stretched 1.2 times using a roll nip type longitudinal uniaxial stretching machine at 135 ° C. to obtain a retardation film 1 having a thickness of 90 μm. The retardation of the retardation film 1 was such that the in-plane retardation (R0) was 60 nm, and the optical axis was −1 to + 1 ° over the entire width. Further, the retardation film 1 had a total light transmittance of 93% and a haze of 0.2%.

Example 4
In Example 3, the retardation film 2 was obtained in the same manner as in Example 3 except that the film 2 was used instead of the film 1 and the stretching temperature was 135 ° C. As for the phase difference of the retardation film 2, the in-plane retardation (R0) was 63 nm. The retardation film 2 had a total light transmittance of 93% and a haze of 0.2%.

Comparative Example 3
A retardation film 3 was obtained in the same manner as in Example 3 except that the film 3 was used. The retardation of the retardation film 3 was such that the in-plane retardation (R0) was 63 nm, and the optical axis was −1 to + 1 ° over the entire width. Further, the retardation film 3 had a total light transmittance of 93% and a haze of 1.5%, and fogging occurred on the film surface.

Example 5
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. On the surface of this polarizing film, using the water-based pressure-sensitive adhesive obtained in Preparation Example 1, the film 1 prepared in Example 1 and the stretched film 1 prepared in Example 3 were each adhered to the polarizing film one side at a time. 1) was obtained. The transmittance and polarization degree of this polarizing plate (1) were measured and found to be 43% and 99.99%, respectively. In addition, when the polarizing plate (1) is placed in a crossed Nicols state and irradiated from one side with a backlight having a luminance of 10000 cd, even if observed from the other side, striped unevenness due to light leakage is completely confirmed. Was not.

Comparative Example 5
A polarizing plate (2) was obtained in the same manner as in Example 5 except that the film 3 was used instead of the film 1 and the stretched film 3 was used instead of the stretched film 1. The transmittance and polarization degree of the polarizing plate were measured and found to be 42% and 99.89%, respectively. Moreover, when the polarizing plate (2) was placed in a crossed Nicol state with two sheets and irradiated from one side with a backlight having a luminance of 10000 cd, light leakage that was attributed to diffused light was observed when observed from the other side.

  The optical film and polarizing plate of the present invention are various liquid crystal display elements such as mobile phones, digital information terminals, pagers, navigation, liquid crystal displays for vehicles, liquid crystal monitors, light control panels, displays for OA equipment, and displays for AV equipment. Or an electroluminescence display element or a touch panel. 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.

Claims (2)

A method for producing an optical film, comprising melting a cyclic olefin-based resin, extruding the resin from a die, and pressing into a cooling roll by a method satisfying the following conditions (1) to (3).
(1) The material of the surface of the cooling roll is a ceramic selected from aluminum oxide, tungsten carbide, and chromium oxide.
(2) The surface roughness of the cooling roll surface is 0.1 to 0.5 s.
(3) The pressure bonding of the molten resin to the cooling roll is performed by electrostatically applying to the film at a voltage of 2 to 8 kV for 0.5 to 5 seconds. The method for producing an optical film according to claim 1, further comprising stretching.