JP2008208357A - Process for producing optical film, optical film, retardation film and polarizing plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical film that has no spot defects, good durability and excellent workability with the occurrence of no deposits during the film-forming process, by melt-extruding a composition excellent in heat resistance produced by blending a specific cycloolefin polymer in combination with a specific antioxidant and a specific ultraviolet absorber. <P>SOLUTION: The optical film suitable for a retardation film and a polarizing plate is produced by melt-extruding a composition which comprises, based on (1) 100 pts.wt. polymer comprising a hydrogenation product of a cycloolefin (co)polymer having a specific structural unit, (2) 0.1-4 pts.wt. alkyl group-substituted phenol compound having a melting point in the range of (Tg)-35°C to (Tg)+75°C, wherein Tg is a glass transition temperature of the polymer (1), and (3) 0.1-4 pts.wt. benzotriazole compound having a melting point in the range of (Tg)-35°C to (Tg)+75°C, wherein Tg is a glass transition temperature of the polymer (1). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing an optical film and an optical film, in which a composition excellent in heat resistance prepared by combining a specific cyclic olefin polymer in combination with a specific antioxidant and an ultraviolet absorber is melt-extruded.

  Conventionally, polymethyl methacrylate, polycarbonate, polystyrene, 3-methylpentene resin, and the like are known as transparent resins. These resins are produced in large quantities industrially and are used in large quantities in various fields by taking advantage of their good transparency. However, these resins do not necessarily have sufficient heat resistance. For example, even in the polycarbonate that is the most heat-resistant resin among the above resins, the glass transition temperature that is an index of the heat resistance is about 150 ° C., Development of a resin having higher heat resistance is desired.

  As a resin having excellent transparency and higher heat resistance, a ring-opening polymer of a norbornene derivative having a polar substituent has been proposed. However, the ring-opening polymer of norbornene derivative has a carbon-carbon double bond in its main chain, so it undergoes oxidative degradation at high temperatures and is practical as a heat-resistant polymer despite having a high glass transition temperature. It was not converted. For this reason, attempts have been made to improve the oxidative degradation by hydrogenating the ring-opening polymer. This improvement in oxidative degradation due to hydrogenation can greatly improve the oxidative degradation resistance compared to conventional non-hydrogenated polymers, but in the case of a high heat resistant resin having a high glass transition temperature, it is unavoidable. In particular, it is necessary to increase the processing temperature. For this reason, deterioration during processing, particularly yellowing coloring, still remains a problem.

For this reason, Patent Document 1 (WO99 / 38918) proposes a cyclic olefin thermoplastic resin composition in which an ultraviolet absorber or an antioxidant is blended with a cyclic olefin thermoplastic resin. However, for an optical film using a cyclic olefin-based thermoplastic resin, it is necessary to further improve weather resistance in order to prevent surface defects caused by deterioration of the resin called point defects at a high level. For this reason, it may be necessary to increase the amount of ultraviolet absorbers and antioxidants. However, if these additives are simply increased, the additives sublimate or decompose in the film forming process and adhere to the film surface or molding machine. And the problem of aging changes that the additive in the film bleeds out. The film surface adhesion or bleed-out of the additive causes a point-like defect derived from the deposit or causes the optical properties of the film to deteriorate.
WO99 / 38918

  In the present invention, a composition excellent in heat resistance prepared by combining a specific cyclic olefin-based polymer in combination with a specific antioxidant and an ultraviolet absorber is melt-extruded, so that there is no point defect and durability. In addition, an object of the present invention is to provide an optical film that is free from deposits during film formation and excellent in workability.

The present invention relates to (1) 100 parts by weight of a polymer having a structural unit represented by the following general formula (I) (hereinafter also referred to as “polymer (1)” or “resin (1)”).
(2) 0.1 to 4 parts by weight of an alkyl group-substituted phenolic compound (hereinafter also referred to as “compound (2)”) having a melting point in the range of the glass transition temperature (Tg) of the polymer to −35 ° C. to Tg + 75 ° C. And (3) 0.1 to 4 parts by weight of a benzotriazole-based compound (hereinafter also referred to as “compound (3)”) having a melting point in the range of glass transition temperature (Tg) of the polymer to 35 ° C. to Tg + 75 ° C. The present invention relates to a method for producing an optical film, wherein the composition is melt-extruded.

(In the general formula (I), R ^{1 to} R ⁴ are a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 30 carbon atoms, 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.)
Here, the compound (2) and the compound (3) preferably each have a thermal weight loss rate of 20% by weight or less when held at 280 ° C. for 1 hour.
Moreover, in the manufacturing method of the optical film of this invention, it is preferable to film-form by melt-transferring the melt of the said composition to a transfer roll.
Next, this invention relates to the optical film obtained by the manufacturing method of the said optical film.
Here, when the optical film is uniaxially stretched at a stretch ratio of 1.3 to 2.7 times at a temperature of Tg + 5 ° C. or higher of the polymer (1), the optical film is given to the transmitted light of the stretched film. It is preferable that the phase difference (Re) satisfies the following formula.
[(Re / film thickness) / stretch ratio]> 3.0 × 10 ⁻³
(Re: retardation value expressed in nm, film thickness: nm)
Next, the present invention relates to a retardation film comprising the above optical film.
Next, this invention relates to the polarizing plate characterized by using the said optical film as a protective film in at least one surface.

  According to the present invention, by melting and extruding a composition excellent in heat resistance blended with a specific cyclic olefin-based polymer in combination with a specific antioxidant and an ultraviolet absorber, there are no point defects, An optical film having good durability and having no work of deposits during film formation and excellent workability can be obtained.

Polymer (1)
Examples of the polymer (1) used in the optical film of the present invention include the following (co) polymers.
(A) A (co) polymer obtained by hydrogenating a ring-opening (co) polymer of a specific monomer represented by the following general formula (II).
(B) A copolymer obtained by hydrogenating a ring-opening copolymer of a specific monomer represented by the following general formula (II) and a copolymerizable monomer.

(In the general formula (II), R ^{1 to} R ⁴ , m and p are the same as those in the general formula (I).)

<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 (II), 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
Is a hydrogen atom or a monovalent organic group, at least one of R ² and R ⁴ represents a polar group having a polarity other than a hydrogen atom or a hydrocarbon group, m is an integer of 0 to 3, and p is 0 It is an integer of -3, More preferably, m + p = 0-4, More preferably, it is 0-2, Most preferably, m = 1, p = 0. The specific monomer having m = 1 and p = 0 is preferable in that the obtained polymer (1) 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, a 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 polymer having a high glass transition temperature, low hygroscopicity, and various properties. It is preferable at the point which has the outstanding adhesiveness with material. 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 a smaller n value is preferable in terms of heat resistance because the glass transition temperature of the resulting polymer (1) does not decrease, and n is 0. The specific monomer is preferable in that its synthesis is easy.

In the general formula (II), R1 or R3 is preferably an alkyl group, preferably an alkyl group having 1 to 4 carbon atoms, more preferably an alkyl group having 1 to 2 carbon atoms, particularly preferably a methyl group, In particular, this alkyl group is bonded to the same 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, (A) a ring-opening (co) polymer of a specific monomer, and (B) a ring-opening polymerization reaction for obtaining a ring-opening copolymer of a specific monomer and a copolymerizable monomer Is carried out in the presence of a metathesis 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.

(A) Representative examples of suitable W, the compounds of Mo or Re as a _component, WCl6, MoCl 6, ReOCl ₃ JP 1-132626 page 8, lower left column, line 6 - page 8, right upper column, such as Mention may be made of the compounds described in line 17.
(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 carboxylic acid esters such as ethyl acetate, n-butyl acetate, iso-butyl acetate and methyl propionate, di Chirueteru, 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.

  (B) 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. Further, polybutadiene, polyisoprene, etc. In the presence of an unsaturated hydrocarbon polymer containing two or more carbon-carbon double bonds in the main chain, such as a conjugated diene compound, a styrene-butadiene copolymer, an ethylene-nonconjugated diene copolymer, or polynorbornene. The specific monomer may be subjected to ring-opening polymerization.

The ring-opening (co) polymer obtained as described above is further hydrogenated to obtain a polymer (1) suitable for optical applications used in the present invention.
<Hydrogenation catalyst>
In the hydrogenation reaction, a hydrogenation catalyst is added to a usual method, that is, a solution of a ring-opening (co) polymer, and hydrogen gas at normal pressure to 300 atm, preferably 3 to 200 atm, is added to 0 to 200 ° C., Preferably it is performed by operating at 20 to 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.
Thus, the polymer (1) obtained by hydrogenation has excellent thermal stability, and its characteristics are not deteriorated by heating during molding or use as a product. . Here, the hydrogenation rate is usually 50% or more, preferably 70% or more, and more preferably 90% or more.

Further, the hydrogenation rate of the polymer (1) is 50% or more, preferably 90% or more, more preferably 98% or more, particularly preferably 99% or more, most measured by 500 MHz and ¹ H-NMR. Preferably it is 99.5% or more. The higher the hydrogenation rate, the better the stability to heat and light.
In the polymer (1) used in the present invention, the gel content contained in the polymer (1) is preferably 5% by weight or less, more preferably 1% by weight or less.

The glass transition temperature (Tg) of the polymer (1) thus obtained is usually 100 ° C to 250 ° C, preferably 110 ° C to 200 ° C, more preferably 120 ° C to 180 ° C. If Tg is less than 100 ° C, the heat distortion resistance may be insufficient. On the other hand, if Tg exceeds 250 ° C, it is necessary to perform melt extrusion at a very high temperature. Resin is thermally deteriorated, mechanical properties are reduced, and foreign materials such as burns and gels are generated on the surface or inside, resulting in reduced surface uniformity and coloration. It can be difficult.
In addition, the glass transition temperature of a polymer (1) can be easily adjusted with methods, such as using a specific monomer from which a structure differs combining in combination with a copolymerizable monomer.

The intrinsic viscosity (η _inh ) at 30 ° C. of the polymer (1) measured with a Ubbelohde viscometer using a chloroform solution is usually 0.35 to 2.0 dl / g, preferably 0.4. It is -1.5 dl / g, More preferably, it is 0.45-1.0 dl / g.
Furthermore, the polystyrene-equivalent number average molecular weight (Mn) measured by gel permeation chromatography (GPC: tetrahydrofuran solvent) is usually 1,000 to 500,000, preferably 2,000 to 300,000, more preferably 5, The weight average molecular weight (Mw) is usually 5,000 to 2,000,000, preferably 10,000 to 1,000,000, and more preferably 30,000 to 500,000.
When the intrinsic viscosity (η _inh ) is less than 0.35 dl / g, the number average molecular weight (Mn) is less than 1,000, or the weight average molecular weight (Mw) is less than 5,000. The polymer (1) may have extremely low strength. On the other hand, when the intrinsic viscosity (η _inh ) exceeds 2.0 dl / g, the number average molecular weight (Mn) exceeds 500,000 or the weight average molecular weight (Mw) exceeds 2 million. (1) The melt viscosity becomes too high, and it becomes difficult to remove foreign substances with a polymer filter, or because of deterioration of resin due to shear heat generation, thermal deterioration due to high-temperature processing, etc., a high-quality film suitable for optics is required. It can be difficult to obtain.

Alkyl group-substituted phenol compounds (2)
Next, the alkyl-substituted phenolic compound (2) used in the present invention reacts with active radicals that cause deterioration of the polymer (1) by preventing the deterioration of the polymer (1) and generating heat or ultraviolet rays. Thus, the active species is changed to a stable form to prevent deterioration of the polymer.
The melting point of the alkyl-substituted phenol compound (2) is the glass transition temperature (Tg) of the polymer (1) -35 ° C to Tg + 75 ° C, preferably Tg-30 ° C to Tg + 70 ° C. When the temperature is lower than Tg-35 ° C., the vapor pressure of the compound increases and the volatility increases, so that the compound itself, production, heat during processing, decomposition products due to oxygen are generated, and cooling (casting) rolls and films There is a problem of sticking to. On the other hand, when the temperature is higher than Tg + 75 ° C., a compound whose fluidity has increased due to high heat during production and processing bleeds to the surface of the resin composition, and since it has a high melting point in the cooling process, it cannot be compatible and solidifies on the surface. There is a problem of adhering to the roll or film surface.
The alkyl-substituted phenol compound (2) has a thermal weight loss rate of preferably 20% by weight or less, more preferably 10% by weight or less when the compound is held at 280 ° C. for 1 hour. If it exceeds 20% by weight, the amount of volatiles during processing by applying heat, such as during production of the film of the present invention, and by-products that may be generated by thermal decomposition may increase, and film formation It is not preferable because it may adhere to the machine or the film surface.
The above alkyl group-substituted phenol compound (2) is, for example, represented by the following general formula (III).

(In the general formula (III), R ⁵ represents an a-valent organic group having at least one ester bond, amide bond or ether bond, and R ⁶ and R ⁷ each independently represents an alkyl group. ⁶ and R ⁷ may be the same or different, and a represents an integer of 2 to 4.)
In the general formula (III), the organic group represented by R ⁵ is preferably a group represented by the following formula (III-1).

(In the general formula (III-1), R ⁸ represents a hydrocarbon group obtained by removing a hydrogen atom from a hydrocarbon; or a heterocyclic-containing organic group obtained by removing a hydrogen atom from a heterocyclic compound, A represents at least one linking group selected from —COO—, —OCO—, —O—, —CONH—, and —NHCO—, and R ⁹ represents a monovalent hydrocarbon group or a heterocyclic-containing organic group. )
In formula (III-1), as R ⁸ ,
Alkanes having 1 to 10 carbon atoms such as methane, ethane, propane, i-propane, n-butane, i-butane, t-butane, n-heptane, n-hexane;
C3-C10 cycloalkane such as cyclopentane, cyclohexane, cyclooctane;
C6-C20 aromatic hydrocarbons such as benzene, naphthalene, bisphenol, anthracene, toluene;
A hydrocarbon group obtained by removing a hydrogen atom from a hydrocarbon compound such as
Examples thereof include heterocyclic-containing organic groups in which a hydrogen atom is removed from a heterocyclic-containing compound such as pyrrolidine, piperidine, imidazolidine, piperazine, morpholine, pyrrole, imidazole, pyridine, pyrazine, and pyrimidine.
In formula (III-1), examples of R ⁹ include a hydrocarbon group or a heterocyclic ring-containing organic group obtained by removing one hydrogen atom from the hydrocarbon compound or heterocyclic group-containing compound.

Specific examples of the alkyl group-substituted phenol compound (2) include pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, 1- [2- [3-3]. , 5-Di-tert-butyl-4-hydroxyphenyl) propionyloxy] ethyl] -4- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy] 2,2,6 6-tetramethylpiperidine, 3,9-bis [2- {3 (3-tert-butyl-4-hydroxy5-methylphenyl) propionyloxy} -1,1-dimethylethyl] -2,4,8, 10-tetraoxaspiro [5.5] undecane, bis- [3,3-bis- (4′-hydroxy-3′-t-butylphenyl) butanoic acid] glycol ester, and the like. Used in selecting compounds having a glass transition temperature (Tg) -35 ℃ ~Tg + 75 ℃ melting point of the polymer (1) used in.
These alkyl group-substituted phenolic compounds (2) can be used alone or in combination of two or more.

  The addition amount of the alkyl group-substituted phenol compound (2) is 0.1 to 4 parts by weight, preferably 0.2 to 3 parts by weight with respect to 100 parts by weight of the polymer (1). If the amount is less than 0.1 parts by weight, the amount of the processed product is insufficient because the amount is insufficient, such as coloring during production of the composition or processing such as film formation, and frequent occurrence of point defects in the film due to gelation. There is a problem of lowering. On the other hand, when the amount exceeds 4 parts by weight, there is a problem that the hue of the film deteriorates due to the effect of coloring by quinone generated by the deterioration of the compound, or the compound itself and a decomposition product are liable to adhere due to bleeding from the composition. .

Benzotriazole compounds (3)
The benzotriazole-based compound (3) suppresses generation of active radical species that cause deterioration of the polymer (1) by absorbing ultraviolet rays, and is mainly effective when using the formed optical film. To prevent coloring and transparency deterioration caused by deterioration.
The melting point of the benzotriazole compound (3) is the glass transition temperature (Tg) of the polymer (1) -35 ° C to Tg + 75 ° C, preferably Tg-30 ° C to Tg + 70 ° C, like the compound (2). If it is lower than Tg-35 ° C., the vapor pressure of the compound increases and the volatility increases, so that the compound itself, production, heat during processing, decomposition products due to oxygen are generated, and cooling (casting) rolls and films There is a problem of sticking. on the other hand. When the temperature is higher than Tg + 75 ° C., a compound having increased fluidity due to high heat during production and processing bleeds to the surface of the composition, and since it has a high melting point in the process of molding and cooling, it cannot be compatible and solidifies on the surface. There is a problem of adhering to the surface.
The benzotriazole compound (3) preferably has a thermal weight loss rate of 20% by weight or less, similar to the alkyl group-substituted phenol compound (2), when the compound is held at 280 ° C. for 1 hour. Preferably it is 10 weight% or less. If it exceeds 20% by weight, the amount of volatiles during processing by applying heat, such as during production of the film of the present invention, and by-products that may be generated by thermal decomposition may increase, and film formation It is not preferable because it may adhere to the machine or the film surface.

  Specific examples of the benzotriazole compound (3) include 2,2′-methylenebis [4- [1,1,3,3-tetramethylbutyl] -6- (2H-benzotriazol-2-yl). Phenol], 2- (3,5-di-tert-butyl-2-hydroxyphenyl) benzotriazole, 2- [2′-hydroxy-3 ′, 5′-bis- (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole, 2- [2′-hydroxy-3 ′-(1-methyl-1-phenylethyl) -5 ′-(1,1,3,3-tetramethylbutyl) -benzotriazole and the like. These can be used alone or in combination of two or more.

  The addition amount of the benzotriazole-based compound (3) is 0.1 to 4 parts by weight, preferably 0.2 to 3 parts by weight with respect to 100 parts by weight of the polymer (1). If the amount is less than 0.1 parts by weight, there is a problem that the effect of addition may not be seen. On the other hand, if the amount exceeds 4 parts by weight, the influence of the light absorption wavelength of the compound increases, and the formed optical film has a problem. There is a problem that the light transmittance in the visible light region, which is indispensable for the quality of the film, is also lowered.

Other Additives In the present invention, additives other than the above essential (2) to (3) components such as a lubricant, other ultraviolet absorbers, dyes or pigments are used within a range not impairing the effects of the present invention. be able to. Of course, even in this case, in the case of an additive having a melting point, the melting point is preferably in the range of the melting points of the essential components (2) to (3) of the present invention.

Hereinafter, although an example is given and demonstrated about installations, such as an extruder used by this invention, the present invention is not limited to these examples.
In the melt extrusion method in the present invention, usually, before the polymer (1) (and the above components (2) to (3)) is charged into an extruder, the moisture and gas contained in the polymer ( The resin is dried at an appropriate temperature of Tg or less for the purpose of removing oxygen and the like) and residual solvent in advance.
Although the dryer used for drying is not specifically limited, Usually, an inert gas circulating dryer such as a hot air circulating dryer, a dehumidifying dryer, a vacuum dryer, or nitrogen is used as the polymer (1). It is particularly preferable to use an inert gas circulation drier or a vacuum drier from the viewpoint of efficiently removing volatile components or dissolved oxygen. In order to suppress moisture absorption and oxygen absorption in the hopper, it is also preferable to seal the hopper with an inert gas such as nitrogen or argon, or to use a vacuum hopper that can be kept under reduced pressure. Furthermore, the extruder cylinder may be provided with a vent function to remove volatile components generated during melt extrusion and a function to seal with an inert gas such as nitrogen or argon in order to push the deterioration of the polymer due to oxygen contamination. preferable.

As an extrusion molding method, the resin is melted by an extruder, and a fixed amount is supplied by a gear pump, impurities are removed by filtration with a metal filter, the film is shaped by a die, and the film is drawn by using a take-up machine. A method is generally used in which the is cooled and wound using a winder.
As an extruder used for extrusion molding, any of a single screw, a twin screw, a planetary type, a kneader, a Banbury mixer type and the like may be used, but a single screw extruder is preferably used. In addition, there are vent type, tip dull mage type, double flight type, full flight type, etc. as extruder screw shape, and compression type includes slow compression type, quick compression type, etc., but full flight type slow compression. Type is preferred.
For gear pumps used for metering, there are internal lubrication systems in which the resin returned from the downstream side between the gears enters the system and external lubrication systems that are discharged to the outside. preferable. As for the gear teeth of the gear pump, the helical type is more preferable than the direction parallel to the shaft from the viewpoint of stabilization of measurement.
Regarding the filter used for filtering foreign matter, there are leaf disc type, candle filter type, leaf type, screen mesh, etc., but leaf disc type with relatively small residence time distribution and large filtration area. Are preferred. Examples of the filter element include a metal fiber sintered type, a metal powder sintered type, and a metal fiber / powder laminated type.
The shape of the center pole of the filter includes external flow type, hexagonal column internal flow type, cylindrical internal flow type, etc., but any shape can be selected as long as the retention part is small, The external flow type is preferable.

The molten polymer (1) (and components (2) to (3)) is discharged from a die, and is solidified on a cooling drum to be formed into a target film. Regarding the die shape, it is essential to make the resin flow inside the die uniform, and in order to maintain the uniformity of the film thickness, the pressure distribution inside the die near the die outlet must be constant in the width direction. Is essential. In addition, the flow rate of the resin in the width direction is almost constant, and the fine adjustment of the flow rate at the die outlet is constant within a range that can be adjusted by the lip opening. It is. In order to satisfy the above conditions, the coat hanger type is preferable for the manifold shape, and the straight manifold, fishtail type and the like are not preferable because the flow rate distribution in the width direction is likely to occur.
Further, in order to make the thickness distribution of the film uniform, it is important to make the temperature distribution at the die exit constant in the width direction, and the temperature distribution is preferably ± 1 ° C. or less, more preferably ± 0.5 ° C. or less. If temperature unevenness occurs in the width direction exceeding ± 1 ° C, a difference in melt viscosity of the resin occurs, resulting in uneven thickness, uneven stress distribution, etc., resulting in uneven retardation during the stretching operation. It becomes easy and it is not preferable.
Furthermore, the amount of lip opening at the die outlet (hereinafter referred to as “lip gap”) is usually 0.05 to 1 mm, preferably 0.3 to 0.8 mm, and more preferably 0.35 to 0 mm. 0.7 mm. If the lip gap is less than 0.05 mm, the resin pressure inside the die becomes too high, and the resin is liable to cause resin leakage from a place other than the lip of the die. On the other hand, if the lip gap exceeds 1 mm, it is difficult to increase the resin pressure of the die, which is not preferable because the uniformity of the thickness in the width direction of the film is deteriorated.

Examples of the method for tightly solidifying the film extruded from the die include a nip roll method, an electrostatic application method, an air knife method, a vacuum chamber method, and a calendar method, and an appropriate method is selected according to the film thickness and application. Is done.
The surface of the cooling roll for solidifying the film extruded from the die is also preferably subjected to various surface treatments as in the case of the extruder cylinder and the inner surface of the die. These surface treatments prevent the adhesion of the extruded film to the roll surface and prevent the occurrence of uneven thickness of the film. Also, the surface accuracy of the cooling roll is increased, and the surface hardness is high, so that the film is not easily scratched. Even if it manufactures, it is preferable at the point which can maintain the film surface precision stably and can manufacture a film without a thickness spot.
In addition, when the melt melt-extruded from the die is closely adhered and solidified, a double-sided transfer type device called a sleeve touch type is used in which a cooling belt that is elastically deformable is disposed on the opposite side of the first cooling roll to the melt. For example, film transfer by double-sided transfer has the effect of improving the surface smoothness of the film, and because the film is in contact with the surface, the molecular orientation at the time of take-up is reduced, which is problematic for melt-extruded films. It is preferable at the point which can manufacture a film with few die lines or optical distortion. In addition, in the production of a resin composition film containing the above components (2) and (3) and other additives as necessary, the temperature change on the film surface is gentle, so the volatiles of the additives are unevenly distributed. Thus, it is difficult to solidify by cooling, which is preferable in that the deposits on the die, roll or film are suppressed.

  Examples of the material of the extruder (cylinder, screw, etc.) and the die include, but are not limited to, SCM steel and stainless steel such as SUS. Also, the inner surface of the extruder cylinder, the die and the screw surface of the extruder are plated with chromium, nickel, titanium, etc., and PVD (Physical Vapor Deposition) method, etc., TiN, TiAlN, TiCN, CrN, DLC It is preferable to use a material in which a film such as (diamond-like carbon) is formed, a tungsten-based material such as WC, a material sprayed with ceramic such as cermet, or a material whose surface is nitrided. Such a surface treatment is preferable in that a uniform molten state of the resin can be obtained because the coefficient of friction with the resin is small.

The resin temperature (extruder cylinder temperature) for producing the optical film of the present invention is usually 200 to 350 ° C., preferably 220 to 320 ° C. If the resin temperature is less than 200 ° C., the resin cannot be melted uniformly. On the other hand, if the resin temperature exceeds 350 ° C., the resin is thermally deteriorated during melting, making it difficult to produce a high-quality film with excellent surface properties. . Furthermore, it is particularly preferable that the temperature is within the above-mentioned temperature range and within the range of Tg + 120 ° C. to Tg + 160 ° C. with respect to the glass transition temperature (Tg) of the resin. For example, if the Tg of the resin is 130 ° C., a particularly preferable temperature range for film production is 250 ° C. to 290 ° C.
The shear rate during melt extrusion is usually 1 to 500 (1 / sec), preferably 2 to 350 (1 / sec), more preferably 5 to 200 (1 / sec). If the shear rate at the time of extrusion is less than 1 (1 / sec), the resin composition cannot be uniformly melted, so that an extruded film with small thickness unevenness cannot be obtained, while it exceeds 500 (1 / sec). If the shear force is too large, the resin composition and additives may be decomposed and deteriorated, and defects such as foaming, die lines, and deposits may occur on the surface of the extruded film.

The thickness of the optical film of the present invention is usually 10 to 800 μm, preferably 20 to 500 μm, more preferably 40 to 500 μm. When the thickness is less than 10 μm, it may be difficult to perform post-processing such as stretching due to insufficient mechanical strength. On the other hand, when the thickness exceeds 800 μm, a film having uniform thickness and surface properties is produced. In addition to being difficult, it may be difficult to wind up the resulting film.
The thickness distribution of the optical film of the present invention is usually within ± 5%, preferably within ± 3%, more preferably within ± 1% with respect to the average value. If the thickness distribution exceeds ± 5%, retardation unevenness may easily occur when a retardation film is obtained by performing a stretching treatment.
The optical film of the present invention has a thermal weight loss rate of 2% by weight or less, preferably 1% by weight or less when heated at 260 ° C. for 1 hour. When the thermal weight reduction rate is 2% by weight or less, it is preferable in that the volatile matter is small and no deposit is generated during film formation, and the weather resistance is excellent.

Retardation film The processing conditions for obtaining the retardation film of the present invention are shown below.
The stretching temperature is usually Tg ± 20 ° C., preferably Tg ± 15 ° C., more preferably Tg + 5 to Tg + 15 ° C., based on the Tg of the polymer (1) contained in the melt-extruded film of the present invention.
The draw ratio is appropriately selected depending on the desired retardation value, and depends on whether it is uniaxial or biaxial, but in the case of uniaxial stretching, it is usually 1.01 to 5 times, preferably 1.1 to Three times, more preferably 1.3 to 2.7 times.

In addition, the melt-extruded film of the present invention has a stretching temperature of Tg + 5 ° C. or higher of the polymer (1) contained in the melt-extruded film, for example, Tg + 10 ° C., and a stretch ratio of 1.3 to 2.7 times. When axially stretched, it is preferable to satisfy the relationship represented by the following formula.
[(Re / film thickness) / stretch ratio]> 3.0 × 10 ⁻³
(Re: retardation value expressed in nm, film thickness: nm)
Here, Tg is a value of Tig (extrapolated glass transition start temperature) obtained by DSC (differential scanning calorimetry) at a temperature rising rate of 10 ° C./min in accordance with JIS K7121.
In addition, the above-described uniaxial stretching method for preliminarily examining the retardation development property during the stretching process of the melt-extruded film has a strain rate of 400% / min during stretching and is substantially perpendicular to the stretching direction. It refers to the case where both ends of the film in the direction are not fixed.
When the melt-extruded film satisfies the relationship represented by the above formula, it is easy to obtain a retardation film having a desired retardation by stretching, with a high yield. On the other hand, when the relationship represented by the above formula is not satisfied, it may be difficult to obtain a desired retardation, and problems such as whitening of the film surface and in-plane variation of retardation may occur. .

In the case of a film obtained by melt-extruding the polymer (1) without using the essential components of the present invention (components (2) to (3) above), the above relationship is often not satisfied and the melt-extruded film is stretched. When it is intended to obtain a desired retardation value, particularly a retardation value of 250 nm or more with a thickness of 20 to 100 μm by processing, severe stretching conditions are often required and are difficult.
On the other hand, in the case of a melt-extruded film obtained using the components (2) to (3) that are essential components of the present invention, the above relationship is often satisfied. A retardation film having a thickness of 20 to 100 μm having a retardation value of 500 nm can be easily obtained.
Note that λ / 2 of 550 nm, which is generally used as a reference wavelength in liquid crystal display technology, is 275 nm, and that a retardation film having such a retardation is very useful as a so-called “λ / 2” plate. well known.

Polarizing plate The polarizing plate of the present invention is a water-based adhesive composed of an aqueous solution mainly composed of PVA resin, the optical film of the present invention obtained as described above on at least one surface of a polarizer composed of a PVA-based film, By sticking together using polar group-containing adhesives, photo-curing adhesives, etc., and heating or exposing them as necessary, pressing them, and bonding (laminating) the polarizer and optical film Can be manufactured.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated more concretely, this invention is not limited to a following example, unless the summary is exceeded. In the following, “part” and “%” are based on weight unless otherwise specified.

<Glass transition temperature: Tg>
Using a DSC6200 manufactured by Seiko Instruments Inc., the temperature increase rate was measured at 20 ° C. per minute under a nitrogen stream.
<Weight average molecular weight and molecular weight distribution>
The weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn) in terms of polystyrene were measured using HLC-8020 gel permeation chromatography (GPC) manufactured by Tosoh Corporation and using tetrahydrofuran (THF) solvent. In addition, Mn represents the number average molecular weight of polystyrene conversion.
<Intrinsic viscosity ([η] _inh )>
A chloroform solvent was used as the solvent, and the measurement was performed with an Ubbelohde viscometer at a polymer concentration of 0.5 g / dl at 30 ° C.

<Thermal weight reduction>
The thermogravimetric decrease of the compound and the film was measured under a nitrogen flow (200 ml / min) using a differential thermothermal gravimetric simultaneous measurement device TG / DTA320 manufactured by Seiko Electronics Industry Co., Ltd. The temperature was raised to a predetermined temperature at 40 ° C./min, and the amount of decrease after 60 min after reaching the temperature was evaluated.
<Total light transmittance / haze>
The total light transmittance and haze of the film were measured using a haze meter HM-150 manufactured by Murakami Color Research Laboratory Co., Ltd.
<Hue (YI)>
The hue (YI) of the film was measured using an X-rite8200 manufactured by Murakami Color Research Laboratory Co., Ltd.
<Phase difference of transmitted light>
The phase difference of the sample was measured using KOBRA-21DH manufactured by Oji Scientific Instruments. The measurement was carried out on a sample obtained by cutting any 10 points from a film having a total width of 1 m, and the average value was used as a retardation value.

<Roll deposit>
In order to investigate the presence or absence of deposits during film formation (additives and their decomposition products, etc.), the presence or absence of the deposits on the casting roll was visually checked. ○: No deposits, ×: There was a deposit.
<Number of point defects>
In order to examine the presence or absence of point-like defects (fluidity, solubility, etc. changed due to resin degradation (gels, those that are about to become gels), five 500 mm square samples were cut from the center of the film, The sample was placed on a table in a dark room, and the number of point defects on the film confirmed by reflected light was counted for a 500 mm square or 200 mm square range.The average value of the above 5 samples was converted into the number per 1 m 2. Expressed.
<Durability evaluation>
Using a sunshine fade meter manufactured by Suga Test Instruments Co., Ltd., the test was conducted under conditions of no rain at 63 ° C., and the surface state, hue (YI) and haze after 500 hours were observed. The surface condition was visually observed and evaluated according to the following criteria.
○: No change Δ: Within 10 mm × 100 mm field of view, no more than 10 microcracks have occurred.
X: Remarkable cracks are generated.

<Synthesis of raw resin>
Synthesis Example 1 <Resin A>
8-methyl-8-methoxycarbonyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene 227.5 parts, bicyclo [2.2.1] hept-2-ene 22.5 parts, 1-hexene (molecular weight regulator) 18 parts, toluene (for ring-opening polymerization reaction) (Solvent) 750 parts were charged into a nitrogen-substituted reaction vessel, and this solution was heated to 60 ° C. Next, 0.62 part of a toluene solution of triethylaluminum (1.5 mol / l) and tungsten hexachloride modified with t-butanol / methanol (t-butanol: methanol: tungsten) were added to the solution in the reaction vessel. 37 parts of a toluene solution (concentration 0.05 mol / l) of 35 mol: 0.3 mol: 1 mol) was added, and this system was heated and stirred at 80 ° C. for 3 hours to cause a ring-opening polymerization reaction. Thus, a ring-opening copolymer solution was obtained. The polymerization conversion rate in this polymerization reaction was 97%.

The autoclave was charged with 4,000 parts of the ring-opening copolymer solution thus obtained, and RuHCl (CO) [P (C ₆ H ₅ ) ₃ ] ₃ 0.48 part was added to the ring-opening copolymer solution. And a hydrogenation reaction was carried out by heating and stirring for 3 hours under the conditions of a hydrogen gas pressure of 100 kg / cm 2 and a reaction temperature of 160 ° C.
After cooling the obtained reaction solution (hydrogenated polymer solution), the hydrogen gas was released. The reaction solution was poured into a large amount of methanol to separate and collect the coagulated product, and dried to obtain a hydrogenated cyclic olefin resin A. The Tg of Resin A was 140 ° C. Moreover, Mn, Mw, and Mw / Mn in terms of polystyrene measured by the GPC method were 24,000, 67,000, and 2.8, respectively, and the intrinsic viscosity (η _inh ) was 0.49 dl / g. .

Synthesis Example-2 <Resin B>
8-methoxycarbonyl-8-methyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene 185.5 parts, dicyclopentadiene (DCP) 62.5 parts, bicyclo [2.2.1] hept-2-ene 2 parts, and 1-hexene (molecular weight adjustment) The same procedure as in Synthesis Example 1 was conducted except that 15 parts of the agent was heated to 100 ° C. to obtain a ring-opening copolymer. The reaction rate was 96%. Further, a hydrogenation reaction was performed in the same manner to obtain a hydrogenated resin B. The glass transition temperature (Tg) of Resin B was 145.0 ° C.
The number average molecular weight (Mn) = 22,000, the weight average molecular weight (Mw) = 66,000, the molecular weight distribution (Mw / Mn) = 3.0, and the intrinsic viscosity (η _inh ) = 0.52.

<Film formation>
Example 1 (Film A-1)
Using a twin-screw extruder, i) (pentaerythrityltetrakis-3- (3,5-di-t-butyl-4-) as an essential alkyl group-substituted phenol compound (2) with respect to 100 parts of resin A Hydroxyphenyl) propionate: melting point 115 ° C. 0.3 part as benzotriazole compound (3) v) (2,2′-methylenebis [4- (1,1,3,3-tetramethylbutyl) -6- ( 2H-benzotriazol-2-yl) phenol]: melting point 199 ° C. After melt-kneading at 270 ° C. at a blending ratio of 1.5 parts, the mixture was extruded onto a strand, cooled to water, and then pellets were obtained through a feeder ruder. The obtained pellets were circulated and dehumidified and dried at 100 ° C. for 3 hours under nitrogen, then sent to a hopper and melted at a resin temperature of 270 ° C. using a single screw extruder having a screw diameter of 75 mmφ.
This molten resin was guided to a 700 mm wide coat hanger die through a polymer filter (aperture 5 μm) heated to 280 ° C. at a rate of 30 kg / hr by a double shaft discharge type gear pump. The differential pressure between the inlet and outlet of the filter was 3 MPa. The die heater was set to 250 ° C. using an aluminum cast heater, and a lip heater was installed in addition to the front lip portion to control the die lip temperature to 250 ± 0.4 ° C.
The lip opening was set to 0.5 mm in the width direction, and fine adjustment was performed by measuring thickness unevenness with an on-line thickness gauge installed on the downstream side of melt extrusion. The resin coming out of the die was dropped in the lead direct wire direction of a 250 mmφ cast roll (surface roughness: 0.1 μm) and crimped, and then pressed in order with two cooling rolls installed horizontally to the cast roll axis, and then peeled off. The tension was controlled at 4 kgf and the sample was taken up. At this time, the peripheral speed of the cast roll was 7.6 m / min, and the distance from the die to the film pressing point of the cast roll was 65 mm. The obtained film having a thickness of 100 μm was designated as film A-1. The state of adhesion of the resin and the like at the die lip outlet after production was confirmed by visual observation, but no deposit was observed.

Example 2 (Film A-2)
Compound (2) is converted to ii) 1- [2- {3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy} ethyl] -4- [3- (3,5-di-t -Butyl-4-hydroxyphenyl) propionyloxy] -2,2,6,6-tetramethylpiperidine Except for changing to 0.3 part, the same operation as in Example 1 was performed to obtain a film A-2.

Example 3 (Film B-1)
A film B-1 was obtained in the same manner as in Example 1 except that the resin A was changed to the resin B and the die temperature was changed to 260 ° C.

Example 4 (Film A-3)
Using a twin-screw extruder, 0) i) pentaerythrityltetrakis-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate as an essential compound (2) is added to 100 parts of resin A. 5 parts, v) 2,2′-methylenebis [4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol] as compound (3) 2 A pellet was obtained in the same manner as in Example 1 at a blending ratio of .5. The obtained pellets were melted in the same manner as in Example 1 and extruded from a 700 mm coat hanger die, pressed onto a 250 mmφ cast roll from the direction of the direct lead wire, and the surface was mirror-finished from the opposite side of the cast roll (surface Roughness: 0.1μ) sleeve-type roll manufactured by Chiba Machine Industry Co., Ltd. (Two holding rolls are inscribed inside, and a 300-μm-thick pipe-shaped metal thin film) has torque against the peripheral speed of the cast roll. The film was driven in a range of 10% of the rating, and the film was elastically deformed and pressed on the cast roll, so that both surfaces of the film were pressed on the surface. The film was sequentially pressure-bonded by the second and third cooling rolls and taken up with a tension of 4 kgf. At this time, the peripheral speed of the cast roll was 7.6 m / min, and the distance from the die to the film pressing point of the cast roll was 65 mm. The obtained film having a thickness of 100 μm was wound up as a film A-3.

Comparative Examples 1-7
Hereinafter, each film (A-4 to 10) of Comparative Examples 1 to 7 was obtained in the same manner as Example 1. Table 1 summarizes each film composition and physical property values shown in the Examples. The physical properties of the compounds used as compounds (2) and (3) are shown in Table 2.

<Stretching of film>
Example 5 (Film A-21)
After heating the film A-1 in a tenter to 143 ° C. and stretching it 1.5 times at a stretching speed of 400% / min, the film A-1 was cooled while being held in this state for about 2 minutes at 110 ° C. The film was further cooled to room temperature and taken out, and both ends were slit to obtain a stretched film A-21 having a width of 300 mm. The obtained film has a light transmittance of 92%, a haze of 0.2%, and a retardation expression calculated by [retardation (nm) / film thickness (nm)] / stretch ratio is 3.21 × 10−. 3. Table 3 shows the stretching conditions and property evaluation results of A-21.

Examples 6-9, Comparative Examples 8-14
Each of the stretched films (A-21 to 31 and B-21) is subjected to the same operation as in Example 5 at the predetermined temperature described in Table 3 using the extruded films mentioned in the examples and comparative examples. Got. The stretching conditions and the property evaluation results are shown in Table 3.

  Comparing Examples 1 to 4 with Comparative Example 1, Comparative Example 1 is poor in thermal stability because it contains few components (2) essential in the present invention, and has many point defects in the extruded film. In Comparative Examples 2 and 7, on the contrary, since the component (2) or (3) is too much, it is affected by decomposition products and the like, deposits on the cast roll are generated, and the point defects of the film also increase. . In Comparative Examples 3 and 4, since the melting point of the compound (2) is too low or too high with respect to the polymer (1), deposits increase due to volatilization and decomposition of the compound. In Comparative Examples 5 and 6, since only one of the essential compounds (2) and (3) is contained, the number of point-like defects is increased and the durability of the film obtained by stretching the film (Comparative Example 8) is deteriorated. . Moreover, in Comparative Example 12, it can be seen that the retardation development property of a film obtained by stretching a film having a too low melting point of the compound (2) is deteriorated, and the effect of the present invention is not obtained.

  The optical film obtained by the present invention includes various liquid crystals such as mobile phones, digital information terminals, pagers, navigation, in-vehicle liquid crystal displays, liquid crystal monitors, liquid crystal televisions, light control panels, displays for OA devices, and displays for AV devices. It can be used for retardation films such as display elements, electroluminescence display elements or touch panels, polarizing plate protective films, viewing angle compensation films, light diffusion plates, display substrates, and the like. 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 (7)

(1) For 100 parts by weight of a polymer having a structural unit represented by the following general formula (I):
(2) 0.1-4 parts by weight of an alkyl group-substituted phenolic compound having a melting point in the range of the glass transition temperature (Tg) of -35 ° C to Tg + 75 ° C of the polymer, and (3) a melting point of the glass of the polymer. A method for producing an optical film, comprising melt-extruding a composition having 0.1 to 4 parts by weight of a benzotriazole-based compound having a transition temperature (Tg) in the range of -35 ° C to Tg + 75 ° C.

(In the general formula (I), R ^{1 to} R ⁴ are a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 30 carbon atoms, 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.)   The method for producing an optical film according to claim 1, wherein the (2) phenolic compound and (3) benzotriazole compound each have a thermal weight loss rate of 20% by weight or less when held at 280 ° C. for 1 hour.   The method for producing an optical film according to claim 1, wherein the melt of the composition is transferred onto a transfer roll on both sides to form a film.   The optical film obtained by the manufacturing method of the optical film in any one of Claims 1-3. When the polymer (1) is uniaxially stretched at a stretch ratio of 1.3 to 2.7 at a temperature of Tg + 5 ° C. or higher, the retardation (Re) given to the transmitted light of the obtained stretched film satisfies the following formula. The optical film according to claim 4.
[(Re / film thickness) / stretch ratio]> 3.0 × 10 ⁻³
(Re: retardation value expressed in nm, film thickness: nm)   A retardation film comprising the optical film according to claim 4.   A polarizing plate comprising the optical film according to claim 4 or 5 as a protective film on at least one surface.