JP6682797B2 - Optical film, polarizing plate and display device - Google Patents

Description

  The present invention relates to an optical film, a polarizing plate and a display device. More specifically, the present invention relates to an optical film that suppresses the occurrence of display unevenness when the optical film is curved, a polarizing plate using the same, and a display device.

  2. Description of the Related Art In recent years, display devices such as liquid crystals and organic electroluminescence elements (hereinafter, also referred to as organic EL elements) are required to have curved surface display suitability as their applications are expanded.

  Examples of the member of the display device include an optical film having a specific retardation to adjust the viewing angle (hereinafter, also referred to as a retardation film). As a typical material of the retardation film, a cycloolefin resin is used, and in addition to high transparency, it is attracting attention as a film material having excellent stability in moisture absorption resistance and moisture permeability. .

  However, even a retardation film using the cycloolefin-based resin, in which display unevenness did not occur in the conventional flat-panel display device, has a problem that display unevenness occurs when arranged in a curved shape. I found out.

  By investigating the cause of the occurrence of display unevenness, by arranging the retardation film in a curved surface shape, a local stress is generated in the retardation film to cause partial distortion in the film, It was found that the cause was the loss of uniform adhesion of the.

  In Patent Document 1, a cycloolefin-based resin has been studied for the purpose of optical disk use, focusing on the effect of improving the adhesion to the recording layer. However, physical properties of the film, suitability for a polarizing plate, suitability for a display device No consideration or suggestion has been made regarding the problems and the like when arranged in a curved surface shape. Therefore, as a member of the display device, the appearance of an optical film using a cycloolefin resin that improves uniform adhesion with a polarizer when arranged in the curved surface shape and suppresses the occurrence of display unevenness is awaited. There is.

JP 2001-187815 A

  The present invention has been made in view of the above problems and circumstances, and a problem to be solved is a cycloolefin-based copolymer having high suitability for curved surface display and suppressing the occurrence of display unevenness when the optical film is curved. An optical film using the above, a polarizing plate using the same, and a display device.

  The present inventor, in order to solve the above problems, in the process of examining the cause of the above problems, an optical film containing a cycloolefin-based copolymer having a structure derived from a cycloolefin-based nomer having a specific group. Then, they have found that the above problems can be solved by an optical film in which the pH value of a liquid obtained by immersing the film in decarbonated water is within a specific range, and have reached the present invention.

  That is, the above-mentioned subject concerning the present invention is solved by the following means.

（式中、ｐ＝１、Ｂ^１及びＢ^２＝Ｈ、Ｂ^３＝Ｍｅ、及びＢ^４＝ＣＯＯＨである。） 1. At least an optical film containing a cycloolefin-based copolymer having a structure derived from a cycloolefin-based monomer having a carboxy group,
The cycloolefin-based monomer has a structure represented by the following general formula (a),
The pH value when a solution obtained by immersing the entire optical film cut into 5 cm squares in 15 mL of decarbonated water at a liquid temperature of 23 ° C. for 15 minutes in a nitrogen atmosphere was within the range of 5.7 to 7.3. Yes, and
An optical film having an equilibrium water content of 4% or less at 25 ° C. and 60% relative humidity.

(In the formula, p = 1, B ¹ and B ² = H, B ³ = Me, and B ⁴ = COOH.)

2 . The copolymerization ratio of the cycloolefin-based monomer having the structure represented by the general formula (a) is in the range of 1 to 70 mol% with respect to the entire cycloolefin-based copolymer. The optical film according to item 1 .

3 . A polarizing plate comprising the optical film according to item 1 or 2 arranged on at least one surface of a polarizer.

4 . A display device comprising the polarizing plate according to item 3 .

5 . 5. The display device according to item 4 , wherein the radius of curvature of the display portion of the display device is within a range of 1 to 5000 mm.

  By the above means of the present invention, the curved film display suitability is high, and when the optical film is curved, an optical film using a cycloolefin copolymer that suppresses the occurrence of display unevenness, a polarizing plate and a display device using the same. Can be provided.

  Although the mechanism of action or mechanism of action of the present invention has not been clarified, it is presumed as follows.

The optical film using the cycloolefin copolymer according to the present invention has a low moisture permeability, but can contain a small amount of water. The cycloolefin-based copolymer having a specific structure according to the present invention is obtained by immersing the entire optical film containing the copolymer cut in 5 cm square in 15 mL of decarbonated water having a liquid temperature of 23 ° C. under a nitrogen atmosphere for 15 minutes. Controlling the copolymerization ratio of the monomer having a carboxy group or adjusting the content rate of the monomer having a carboxy group so as to adjust the pH value when measuring the solution from weakly acidic to near neutral. It is presumed that the water content in the optical film can be adjusted, and as a result, the water content in the film can exhibit a function similar to that of the plasticizer.

  Thereby, it becomes possible to relieve the stress generated when the optical film is arranged in a curved shape inside the film, so that the uniformity of the adhesion with the polarizer is increased and the optical function such as the phase difference is improved. It is presumed that the occurrence of display unevenness can be suppressed without impairing it.

  In addition, when the pH value of the optical film is smaller than the numerical range of the present application, the deterioration of the polarizer occurs in the usual durability evaluation due to strong acidity, while when the pH value of the optical film is larger than the numerical range of the present application. Does not exhibit the plasticizing effect, resulting in poor adhesion with the polarizer.

The figure which showed typically an example of the dope preparation process of the solution casting film forming method preferable in this invention, a casting process, a drying process, and a winding process.

The optical film of the present invention is an optical film containing at least a cycloolefin-based copolymer having a structure derived from a cycloolefin-based monomer having a carboxy group, wherein the cycloolefin-based monomer has the following general formula (a). The pH value of a solution obtained by immersing the entire optical film cut into 5 cm squares in 15 mL of decarbonated water having a structure of 23 ° C. at a liquid temperature of 23 ° C. for 15 minutes in a nitrogen atmosphere is 5. It is within the range of 7 to 7.3, and the equilibrium water content at 25 ° C. and 60% relative humidity is 4% or less. This feature is a technical feature common to the inventions according to claims 1 to 5.

The embodiments of the present invention, from the viewpoint of the effect expression of the present invention, the cycloolefin-based monomer is, have a structure represented by the general formula (a), where, P = 1, B ¹ and B ^{2 =} H, it B 3 = is ^Me and B ^{4 =} COOH is can adjust the amount of water contained by controlling the pH value to a specific range of the optical film, co cycloolefin monomer having the structure It is a preferred embodiment that the polymerization ratio is within the range of 1 to 70 mol% with respect to the entire cycloolefin-based copolymer, in order to exhibit the effect of the present invention.

  The optical film of the present invention can be suitably provided in a polarizing plate or a display device. In particular, this makes it possible to provide a display device in which the occurrence of display unevenness is suppressed even if the display device has a curved shape.

  Further, it is a preferable display device for applying the optical film of the present invention that the radius of curvature of the display portion of the display device is within a range of 1 to 5000 mm.

  Hereinafter, the present invention, its components, and modes and modes for carrying out the present invention will be described in detail. In addition, in this application, "-" is used in the meaning which includes the numerical value described before and after that as a lower limit and an upper limit.

<< Outline of the optical film of the present invention >>
The optical film of the present invention is an optical film containing at least a cycloolefin-based copolymer having a structure derived from a cycloolefin-based monomer having a carboxy group, wherein the cycloolefin-based monomer has the following general formula (a). The pH value of a solution obtained by immersing the entire optical film cut into 5 cm squares in 15 mL of decarbonated water having a structure of 23 ° C. at a liquid temperature of 23 ° C. for 15 minutes in a nitrogen atmosphere is 5. It is within the range of 7 to 7.3, and the equilibrium water content at 25 ° C. and 60% relative humidity is 4% or less.

<Measurement of pH value of optical film>
The pH value of the optical film of the present invention can be measured as follows.

"Decarbonated water" is "deionized water" prepared by the method specified in JIS K 8001: 2009 using "ion-exchanged water" or "distilled water" of type A2 or A3 specified in JIS K 0557. use.
Specifically, for example, “ion-exchanged water” specified in JIS K 0557 is bubbled with nitrogen gas for 15 minutes or more to prepare decarbonated water in a nitrogen gas atmosphere. The entire optical film cut into 5 cm squares was immersed in 15 mL of the prepared decarbonated water having a liquid temperature of 23 ° C. for 15 minutes in a nitrogen atmosphere, and a pH electrode was placed in the solution for measurement. A commercially available electrode can be used as the pH electrode, and for example, HM-30R manufactured by Toa DKK Co., Ltd. can be used.

  The cycloolefin-based copolymer having a specific structure according to the present invention is a liquid in which a film containing the copolymer is immersed, by controlling the copolymerization so as to adjust from weakly acidic to near neutral. The amount of water contained in the optical film can be adjusted, and the water in the optical film exhibits a function similar to that of the plasticizer, so that the stress generated when the optical film is arranged in a curved shape is relaxed inside the film. It is presumed that it is possible to improve the uniformity of the adhesion with the polarizer and suppress the occurrence of display unevenness.

  When the pH value of the optical film is less than 5.7, the acidity is strong, so that the deterioration of the polarizer occurs in the durability evaluation. On the other hand, when the pH value of the optical film is more than 7.3, the plasticizing effect is exerted. The pH value is required to be within the range of the present invention, because the poor adhesion with the polarizer may occur.

<Structure of the optical film of the present invention>
[1] Cycloolefin-Based Copolymer The cycloolefin-based copolymer according to the present invention is characterized by being a cycloolefin-based copolymer having a structure derived from a cycloolefin-based monomer having a carboxy group, and a carboxy group It is a resin obtained by copolymerizing a cycloolefin-based monomer having OH and another monomer, or can be obtained by adjusting the content of the cycloolefin-based monomer having a carboxy group.

  Examples of the structure of the cycloolefin-based monomer include norbornene, dicyclopentadiene, tetracyclododecene, ethyltetracyclododecene, ethylidenetetracyclododecene, and tetracyclo [7.4.0.110,13.02,7]. Polycyclic unsaturated hydrocarbons such as trideca-2,4,6,11-tetraene and derivatives thereof; cyclobutene, cyclopentene, cyclohexene, 3,4-dimethylcyclopentene, 3-methylcyclohexene, 2- (2-methylbutyl) Unsaturated hydrocarbons having a monocyclic structure such as -1-cyclohexene, cyclooctene, 3a, 5,6,7a-tetrahydro-4,7-methano-1H-indene, cycloheptene, cyclopentadiene and cyclohexadiene, and derivatives thereof Can be mentioned. The structure of these monomers may have a polar group. Examples of the polar group include a hydroxy group, an alkoxyl group, an epoxy group, a glycidyl group, an oxycarbonyl group, a carbonyl group, an amino group, an ester group and a carboxylic acid anhydride group.

  The cycloolefin-based monomer according to the present invention has a carboxy group (—COOH) as a substituent in the structure of the above-mentioned monomers.

Cycloolefin-based monomer having a carboxyl group according to the present invention, Ru cycloolefin monomer der having a structure represented by the following general formula (a).

（式中、ｐ＝１、Ｂ ^１ 及びＢ ^２ ＝Ｈ、Ｂ ^３ ＝Ｍｅ、及びＢ ^４ ＝ＣＯＯＨである。）
前記シクロオレフィン系モノマーは、前記一般式（ａ）において、ｐ＝１、Ｂ ^１ 及びＢ ^２ ＝Ｈ、Ｂ ^３ ＝Ｍｅ、及びＢ ^４ ＝ＣＯＯＨであることが、他のモノマーと共重合体を形成し、光学フィルムの前記ｐＨ値の制御性を高めることができる構造である。

(In the formula, p = 1, B ¹ and B ² = H, B ³ = Me, and B ⁴ = COOH. )
In the general formula (a), the cycloolefin-based monomer has p = 1, B ¹ and B ² = H, B ³ = Me, and B ⁴ = COOH, and is a copolymer with another monomer. It is a structure that can be formed to enhance the controllability of the pH value of the optical film.

  By using a cycloolefin-based monomer in which the substituent is substituted on one side of the carbon, the symmetry of the molecule is broken, which promotes the diffusion movement of the resin when the solvent volatilizes, and enhances the plastic effect by the water content in the film. Since it is possible to improve the function of relaxing the stress generated when the optical film is arranged in a curved shape inside the film, it is possible to further improve the uniformity of the adhesiveness with the polarizer.

  Specific examples of the compound of the cycloolefin-based monomer having the structure represented by the general formula (a) are shown below, but the invention is not limited to the following specific examples.

  Examples of the copolymerizable monomer copolymerized with the cycloolefin-based monomer according to the present invention include ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, C2-C20 α-olefins such as 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene and their derivatives; norbornene, dicyclopentadiene, tetracyclododecene, ethyltetracyclododecene, ethylidenetetra Polycyclic unsaturated hydrocarbons such as cyclododecene and tetracyclo [7.4.0.110,13.02,7] trideca-2,4,6,11-tetraene and derivatives thereof; cyclobutene, cyclopentene, cyclohexene , 3,4-dimethylcyclopentene, 3-methylcyclohexene , 2- (2-methylbutyl) -1-cyclohexene, cyclooctene, 3a, 5,6,7a-tetrahydro-4,7-methano-1H-indene, cycloheptene, cyclopentadiene, cyclohexadiene and the like. Saturated hydrocarbons and their derivatives; non-conjugated dienes such as 1,4-hexadiene, 4-methyl-1,4-hexadiene, 5-methyl-1,4-hexadiene and 1,7-octadiene;

  Among the copolymerizable monomers, a cycloolefin-based monomer having a structure represented by the following general formula (b-1) or general formula (b-2) is preferable.

（一般式（ｂ−１）中、Ｒ^１〜Ｒ^４は、それぞれ独立に水素原子、ハロゲン原子、酸素、窒素、イオウ又はケイ素を含む連結基を有していてもよい置換又は非置換の炭素原子数１〜３０の炭化水素基；又は極性基を表す。ｐは、０〜２の自然数を表す。）
上記極性基としては、ヒドロキシ基、アルコキシカルボニル基、アリルオキシカルボニル基、アミノ基、アミド基、シアノ基などが挙げられ、これら極性基はメチレン基などの連結基を介して結合していてもよい。また、カルボニル基、エーテル基、シリルエーテル基、チオエーテル基、イミノ基など極性を有する２価の有機基が連結基となって結合している炭化水素基なども極性基として挙げられる。これらの中では、ヒドロキシ基、アルコキシカルボニル基又はアリルオキシカルボニル基が好ましく、特にアルコキシカルボニル基又はアリルオキシカルボニル基であることが、溶液製膜時の溶解性を確保する観点で好ましい。

(In the general formula (b-1), R ^{1 to} R ⁴ are each independently a substituted or unsubstituted carbon which may have a linking group containing a hydrogen atom, a halogen atom, oxygen, nitrogen, sulfur or silicon. Represents a hydrocarbon group having 1 to 30 atoms; or a polar group, and p represents a natural number of 0 to 2.)
Examples of the polar group include a hydroxy group, an alkoxycarbonyl group, an allyloxycarbonyl group, an amino group, an amide group, and a cyano group. These polar groups may be bonded via a linking group such as a methylene group. . 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, and an imino group is bonded as a linking group is also included as the polar group. Of these, a hydroxy group, an alkoxycarbonyl group or an allyloxycarbonyl group is preferable, and an alkoxycarbonyl group or an allyloxycarbonyl group is particularly preferable from the viewpoint of ensuring the solubility during solution film formation.

（一般式（ｂ−２）中、Ｒ^５は、独立に水素原子、炭素数１〜５の炭化水素基、又は炭素数１〜５のアルキル基を有するアルキルシリル基を表す。Ｒ^６は、ヒドロキシ基、アルコキシカルボニル基、アリルオキシカルボニル基、アミノ基、アミド基、シアノ基、フッ素原子、塩素原子、臭素原子、又はヨウ素原子を表す。ｐは、０〜２の整数を表す。）
本発明においては、一般式（ｂ−２）で表されるように、置換基Ｒ^５及びＲ^６が片側炭素に置換されたシクロオレフィンモノマーを用いることで、分子の対称性が崩れたためか溶媒揮発時の樹脂の拡散運動を促進し、均一な膜を形成する観点から好ましい。

(In formula (b-2), R ⁵ independently represents a hydrogen atom, a hydrocarbon group having 1 to 5 carbon atoms, or an alkylsilyl group having an alkyl group having 1 to 5 carbon atoms. R ⁶ represents A hydroxy group, an alkoxycarbonyl group, an allyloxycarbonyl group, an amino group, an amido group, a cyano group, a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom, and p represents an integer of 0 to 2.)
In the present invention, as represented by the general formula (b-2), by using a cycloolefin monomer in which the substituents R ⁵ and R ⁶ are substituted on one side carbon, the symmetry of the molecule is broken or the solvent is used. It is preferable from the viewpoint of promoting the diffusion movement of the resin during volatilization and forming a uniform film.

R ⁵ is preferably a hydrocarbon group having 1 to 3 carbon atoms, and R ⁶ is preferably a hydroxy group, an alkoxycarbonyl group or an allyloxycarbonyl group, and particularly preferably an alkoxycarbonyl group or an allyloxycarbonyl group during solution casting. It is also preferable from the viewpoint of ensuring the solubility.

  The structures of the cycloolefin-based monomers having the structures represented by the general formulas (b-1) and (b-2) are specifically shown below, but not limited to the following specific examples.

  These other monomers copolymerizable with the cycloolefin-based monomer having a carboxy group according to the present invention can be used alone or in combination of two or more kinds.

  When a cycloolefin-based monomer having a carboxy group according to the present invention is copolymerized with another monomer copolymerizable with the same, the copolymerization ratio of the cycloolefin-based monomer having a carboxylic group to the entire copolymer obtained is Is preferably in the range of 1 to 70 mol% in order to exert the effect of the present invention, and more preferably in the range of 10 to 50 mol% and is appropriately selected.

  The cycloolefin-based copolymer according to the present invention is a copolymer obtained by copolymerizing with a cycloolefin-based monomer having a structure represented by the general formula (a) having a norbornene skeleton, and for example, A saturated polymer of the cycloolefin-based monomer and an unsaturated double bond-containing compound, an addition-type copolymer of the cycloolefin-based monomer, a hydrogenated copolymer thereof, and the cycloolefin-based monomer ( It may be an alternating copolymer of a) and methacrylate or acrylate.

  Preferred cycloolefin copolymers according to the present invention include those having a structural unit represented by the following general formula (c-1) or general formula (c-2). Such a cycloolefin-based copolymer has only the structural unit represented by the general formula (c-1), only the structural unit represented by the general formula (c-2), and the general formula (c-1). It may be a copolymer containing each structural unit of the formula (c-2).

  Preferably, it is a copolymer containing the structural unit of the general formula (c-2) alone or a structural unit of both the general formula (c-1) and the general formula (c-2). It is preferable because the obtained cycloolefin copolymer has a high glass transition temperature and an excellent transmittance.

（一般式（ｃ−１）中、Ｘは、−ＣＨ＝ＣＨ−で表される基又は式：−ＣＨ_２ＣＨ_２−で表される基である。Ｒ^１〜Ｒ^３は、それぞれ独立に水素原子；ハロゲン原子；酸素、窒素、イオウ又はケイ素を含む連結基を有していてもよい置換又は非置換の炭素原子数１〜３０の炭化水素基；又は極性基を表す。Ｒ^４はＣＯＯＨを表す。ｐは、０〜２の自然数を表す。）

（一般式（ｃ−２）中、Ｘは、−ＣＨ＝ＣＨ−で表される基又は式：−ＣＨ_２ＣＨ_２−で表される基である。Ｒ^５は、それぞれ独立に水素原子、炭素数１〜５の炭化水素基、又は炭素数１〜５のアルキル基を有するアルキルシリル基、ヒドロキシ基、アルコキシカルボニル基、アリルオキシカルボニル基、アミノ基、アミド基、シアノ基、フッ素原子、塩素原子、臭素原子、又はヨウ素原子を表す。Ｒ^６はＣＯＯＨを表す。ｐは、０〜２の整数を表す。）
本発明に係るシクロオレフィン系共重合体を作製する際の詳細な条件等については、特開２００８−１０７５３４号公報段落００１９〜００３９の記載を参照することができるが、例えば付加重合反応又は開環メタセシス重合反応によって得ることが好ましい（下記合成スキーム１参照。）。重合は触媒の存在下で行われる。付加重合用触媒として、例えば、バナジウム化合物と有機アルミニウム化合物とからなる重合触媒などが挙げられる。開環重合用触媒として、ルテニウム、ロジウム、パラジウム、オスミウム、イリジウム、白金などの金属のハロゲン化物、硝酸塩又はアセチルアセトン化合物と、還元剤とからなる重合触媒；又は、チタン、バナジウム、ジルコニウム、タングステン、モリブデンなどの金属のハロゲン化物又はアセチルアセトン化合物と、有機アルミニウム化合物とからなる重合触媒などが挙げられる。重合温度、圧力等は特に限定されないが、通常−５０〜１００℃の重合温度、０〜４９０Ｎ／ｃｍ^２の重合圧力で重合させる。

(In the formula (c-1), X is a group or the formula represented by _{-CH = CH-: -CH 2 CH 2} - .R 1 ~R 3 is a group represented by are each independently A hydrogen atom; a halogen atom; a substituted or unsubstituted hydrocarbon group having 1 to 30 carbon atoms which may have a linking group containing oxygen, nitrogen, sulfur or silicon; or a polar group, and R ⁴ represents COOH. Represents, and p represents a natural number of 0 to 2.)

(In the formula (c-2), X is a group or the formula represented by _{-CH = CH-: -CH 2 CH 2} - is a group represented by .R ⁵ each independently represent a hydrogen atom, Alkylsilyl group having a hydrocarbon group having 1 to 5 carbon atoms or an alkyl group having 1 to 5 carbon atoms, hydroxy group, alkoxycarbonyl group, allyloxycarbonyl group, amino group, amide group, cyano group, fluorine atom, chlorine Represents an atom, a bromine atom, or an iodine atom, R ⁶ represents COOH, and p represents an integer of 0 to 2.)
The detailed conditions for producing the cycloolefin copolymer according to the present invention can be referred to the descriptions in paragraphs [0019] to [0039] of JP 2008-107534 A, for example, addition polymerization reaction or ring opening. It is preferably obtained by a metathesis polymerization reaction (see Synthesis Scheme 1 below). The polymerization is carried out in the presence of a catalyst. Examples of the addition polymerization catalyst include a polymerization catalyst composed of a vanadium compound and an organic aluminum compound. As a catalyst for ring-opening polymerization, a polymerization catalyst comprising a metal halide such as ruthenium, rhodium, palladium, osmium, iridium or platinum, a nitrate or an acetylacetone compound and a reducing agent; or titanium, vanadium, zirconium, tungsten or molybdenum. And a metal halide or an acetylacetone compound, and a polymerization catalyst composed of an organoaluminum compound. The polymerization temperature, pressure and the like are not particularly limited, but the polymerization is usually performed at a polymerization temperature of -50 to 100 ° C and a polymerization pressure of 0 to 490 N / cm ² .

  Further, the cycloolefin-based copolymer as the film material is preferably one obtained by copolymerizing a cycloolefin-based monomer and then subjecting it to a hydrogenation reaction to convert unsaturated bonds in the molecule into saturated bonds. The hydrogenation reaction is carried out by blowing hydrogen in the presence of a known hydrogenation catalyst. As the hydrogenation catalyst, transition metal compounds / alkyl such as cobalt acetate / triethylaluminum, nickel acetylacetonate / triisobutylaluminum, titanocene dichloride / n-butyllithium, zirconocene dichloride / sec-butyllithium, tetrabutoxytitanate / dimethylmagnesium. Homogeneous catalyst composed of a combination of metal compounds; Heterogeneous metal catalyst such as nickel, palladium, platinum; nickel / silica, nickel / diatomaceous earth, nickel / alumina, palladium / carbon, palladium / silica, palladium / diatomaceous earth , A heterogeneous solid-supported catalyst in which a metal catalyst such as palladium / alumina is supported on a carrier.

  When the unsaturated bond remaining in the molecular chain of the copolymer is saturated by a hydrogenation reaction, the hydrogenation rate is 90% or more, preferably 95% or more, particularly from the viewpoint of light resistance deterioration and weather resistance. It is preferably 99% or more.

  In addition, as another method, the cycloolefin copolymer according to the present invention is obtained by subjecting the cycloolefin monomer to a polymer by a usual ring-opening metathesis polymerization reaction, followed by hydrolysis and acid treatment, It can also be obtained by modifying a part of the ester into a carboxylic acid (see Synthesis Scheme 2).

  For example, in Synthesis Scheme 2, 100 g of the polymer A obtained by the ring-opening metathesis polymerization reaction is dissolved in 500 mL of toluene by stirring at room temperature for 1 hour, and a 10.8 mol / L NaOH aqueous solution is added thereto, and the mixture is heated to 80 ° C. While vigorously stirring for 12 hours (hydrolysis) and allowing to cool, hydrochloric acid was added (acid treatment) for neutralization. After separating the organic phase and the aqueous phase, the operation of adding pure water to the organic phase and removing impurities in the organic phase is repeated twice, and calcium carbonate is added to the obtained organic phase as a desiccant to remove residual water. The desiccant was removed by filtration, and the organic phase was heated and dried under reduced pressure, whereby the target polymer B having a carboxy group can be obtained with a yield of 95%.

<Measurement of carboxylic acid modification rate>
The carboxylic acid modification rate is analyzed by H-NMR according to the following procedure.

  The sample is dissolved in a deuterated chloroform solvent and H-NMR measurement is performed.

  In the polymer B as compared with the polymer A, the peak derived from the methyl group hydrogen of the ester moiety observed at around 3.6 ppm is different from the peak derived from alkyl hydrogen other than the above which appears over 0.5 to 2.5 ppm. The ratio was decreased, and the carboxylic acid-modified monomer ratio of the polymer B having a carboxy group was calculated from the ratio, and it was 25%.

The cycloolefin-based copolymer according to the present invention has a preferable molecular weight of 0.2 to ⁵ cm ³ / g, more preferably 0.3 to ³ cm ³ / g, and particularly preferably 0.4 to 10 in intrinsic viscosity [η] inh. was 1.5 cm ³ / g, number average molecular weight in terms of polystyrene measured by gel permeation chromatography (GPC) (Mn) is 8,000 to 100,000, more preferably 10,000 to 80,000, particularly preferably from 12,000 to 50,000, The weight average molecular weight (Mw) is preferably 20,000 to 300,000, more preferably 30,000 to 250,000, particularly preferably 40,000 to 200,000.

  When the intrinsic viscosity [η] inh, the number average molecular weight and the weight average molecular weight are in the above ranges, the heat resistance, water resistance, chemical resistance, mechanical properties of the cycloolefin copolymer and the optical film of the present invention are obtained. The molding processability of is improved.

  The glass transition temperature (Tg) of the cycloolefin copolymer according to the present invention is usually 110 ° C or higher, preferably 110 to 350 ° C, more preferably 120 to 250 ° C, and particularly preferably 120 to 220 ° C. . It is preferable that the Tg is 110 ° C. or higher because deformation is less likely to occur due to use under high temperature conditions or secondary processing such as coating and printing.

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

  In the cycloolefin-based copolymer, a specific hydrocarbon-based resin or a known hydrocarbon-based resin described in, for example, JP-A-9-221577 and JP-A-10-287732, as long as the effects of the present invention are not impaired. Thermoplastic resin, thermoplastic elastomer, rubbery polymer, organic fine particles, inorganic fine particles, etc. may be blended, and a specific wavelength dispersant, sugar ester compound, antioxidant, peeling accelerator, rubber particles, plasticizer It may also contain additives such as an ultraviolet absorber.

[2] Other Additives The optical film of the present invention may contain a matting agent, a retardation increasing agent, a plasticizer, an antioxidant, a light stabilizer, an antistatic agent, a release agent and the like. The details of major additives are described below.

[2.1] Matting Agent The optical film of the present invention contains a matting agent in order to impart irregularities to the surface of the film during film formation, ensure slipperiness, and achieve a stable winding shape. It is preferable.

  In addition, the matting agent can also function in order to prevent scratches and deterioration in transportability when the produced film is handled.

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

  The average particle diameter of the primary particles of the fine particles is preferably in the range of 5 to 400 nm, and more preferably in the range of 10 to 300 nm. These may be contained mainly as secondary agglomerates having a particle size of 0.05 to 0.3 μm, and particles having an average particle size of 80 to 400 nm do not agglomerate and are treated as primary particles. It is also preferable that it is included.

  The content of these fine particles in the film is preferably in the range of 0.01 to 1% by mass, and particularly preferably in the range of 0.05 to 0.5% by mass.

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

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

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

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

  In the optical film of the present invention, the coefficient of dynamic friction of at least one surface is preferably within the range of 0.2 to 1.0.

[2.2] Retardation enhancer The retardation enhancer referred to in the present application means a retardation value Rt in the thickness direction of an optical film containing 3 parts by mass of the compound with respect to 100 parts by mass of the cycloolefin copolymer. It means a compound having a function (measured at a light wavelength of 590 nm) of 1.1 times or more as compared with an optical film without addition.

  The retardation increasing agent used in the present invention is not particularly limited and is, for example, a conventionally known disk having an aromatic ring described in paragraphs [0143] to [0179] of JP-A-2006-113239. Compounds (1,3,5-triazine compounds, etc.), rod-shaped compounds described in JP-A 2006-113239, paragraphs [0106] to [0112], JP-A-2012-214682, paragraphs [0118] to [0133]. The described pyrimidine compounds can be used.

[2.3] Plasticizer In the present invention, a polyester resin can be further used as a plasticizer. The polyester resin is obtained by polymerizing a dicarboxylic acid and a diol, and 70% or more of the dicarboxylic acid structural unit (a structural unit derived from the dicarboxylic acid) is derived from an aromatic dicarboxylic acid and the diol structural unit (derived from the diol). 70% or more of the constituent units are derived from the aliphatic diol.

  The ratio of the structural unit derived from the aromatic dicarboxylic acid is 70% or more, preferably 80% or more, more preferably 90% or more.

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

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

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

  Examples of the aliphatic diol include ethylene glycol, 1,3-propylene diol, 1,4-butane diol, 1,4-cyclohexane dimethanol, 1,6-hexane diol, and ester-forming derivatives thereof.

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

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

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

  More preferable polyester resins include polyethylene terephthalate resin, polyethylene terephthalate-isophthalate copolymer resin, polyethylene-1,4-cyclohexanedimethylene-terephthalate copolymer resin, polybutylene terephthalate resin and polyethylene-2,6-naphthalene dicarboxylate. Resins may be mentioned.

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

[2.4] Ultraviolet Absorber The optical film of the present invention preferably contains an ultraviolet absorber in order to shield unnecessary ultraviolet rays applied to the polarizing plate and the display device.

  Examples of the ultraviolet absorber include oxybenzophenone-based compounds, benzotriazole-based compounds, salicylate-based compounds, benzophenone-based compounds, cyanoacrylate-based compounds, nickel complex salt-based compounds, and the like, but less colored benzotriazole-based compounds Compounds are preferred. Further, the UV absorbers described in JP-A-10-182621 and JP-A-8-337574, and the polymer UV absorber described in JP-A-6-148430 are also preferably used.

  When the optical film of the present invention is used as a protective film for a polarizing plate in addition to an optical compensation film, the ultraviolet absorber has an excellent ability to absorb ultraviolet rays having a wavelength of 370 nm or less from the viewpoint of preventing deterioration of a polarizer or liquid crystal. In addition, from the viewpoint of the displayability of the liquid crystal, it is preferable that the liquid crystal display device has a property of absorbing less visible light having a wavelength of 400 nm or more.

  The addition amount of the ultraviolet absorber is preferably in the range of 0.1 to 5.0 mass% with respect to the polymer composition, and more preferably in the range of 0.5 to 5.0 mass%. preferable.

  Examples of the benzotriazole-based UV absorber useful in the present invention include 2- (2'-hydroxy-5'-methylphenyl) benzotriazole and 2- (2'-hydroxy-3 ', 5'-di-t. -Butylphenyl) benzotriazole, 2- (2'-hydroxy-3'-t-butyl-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'-di-t-butyl Phenyl) -5-chlorobenzotriazole, 2- [2'-hydroxy-3 '-(3 ", 4", 5 ", 6" -tetrahydrophthalimidomethyl) -5'-methylphenyl] benzotriazole, 2,2 -Methylenebis [4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol], 2- (2'-hydroxy-3 -T-Butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2- (2H-benzotriazol-2-yl) -6- (linear and side chain dodecyl) -4-methylphenol, octyl-3 -[3-t-Butyl-4-hydroxy-5- (chloro-2H-benzotriazol-2-yl) phenyl] propionate and 2-ethylhexyl-3- [3-t-butyl-4-hydroxy-5- ( Examples thereof include a mixture of 5-chloro-2H-benzotriazol-2-yl) phenyl] propionate, but are not limited thereto.

  In addition, as commercially available products, "TINUVIN 109", "TINUVIN 171", "TINUVIN 326", "TINUVIN 328" (above, product name, manufactured by BASF Japan Ltd.) are preferable. Can be used.

[2.5] Antioxidant The antioxidant delays or prevents the decomposition of the base film due to, for example, halogen as a residual solvent in the base film or phosphoric acid as a phosphoric acid plasticizer. Therefore, it is preferable to incorporate it in the film.

  As such an antioxidant, a hindered phenol-based compound is preferably used, and examples thereof include 2,6-di-t-butyl-p-cresol and pentaerythrityl-tetrakis [3- (3,5-di). -T-Butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis [3 -(3,5-di-t-butyl-4-hydroxyphenyl) propionate], 2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-t-butylanilino)- 1,3,5-triazine, 2,2-thio-diethylenebis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], octa Syl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, N, N'-hexamethylenebis (3,5-di-t-butyl-4-hydroxy-hydrocinnamamide) 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, tris- (3,5-di-t-butyl-4-hydroxy) Benzyl) -isocyanurate and the like.

  In particular, 2,6-di-t-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3 -(3-t-butyl-5-methyl-4-hydroxyphenyl) propionate] is preferred. Further, for example, a hydrazine-based metal deactivator such as N, N'-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyl] hydrazine or tris (2,4-di-). A phosphorus-based processing stabilizer such as t-butylphenyl) phosphite may be used in combination.

[3] Method for producing optical film The optical film of the present invention is preferably a film produced by a solution casting film forming method.

  The optical film of the present invention comprises a step of preparing a dope containing at least a cycloolefin copolymer and an organic solvent (dope preparing step), and casting the dope on a support to form a web (also referred to as a casting film). .) Forming step (casting step), a step of evaporating the solvent from the web on the support (solvent evaporation step), a step of peeling the web from the support (peeling step), and drying the obtained film. Manufactured by a step (first drying step), a step of stretching the film (stretching step), a step of further drying the stretched film (second drying step), and a step of winding the obtained optical film (winding step) Preferably.

  The above steps will be described with reference to the drawings.

  FIG. 1 is a diagram schematically showing an example of a dope preparing step, a casting step, a drying step and a winding step of a solution casting film forming method preferable for the present invention.

  When the matting agent is used, the fine particle dispersion liquid in which the solvent and the matting agent are dispersed by the disperser passes from the charging pot 41 through the filter 44 and is stocked in the stock pot 42. On the other hand, the cycloolefin-based copolymer, which is the main dope, is dissolved together with the solvent in the dissolution pot 1, and the matting agent stored in the stock pot 42 is appropriately added and mixed to form the main dope. The obtained main dope is filtered from the filter 3 and the stock kettle 4 by the filter 6, the additive is added by the merging pipe 20, mixed by the mixer 21, and sent to the pressure die 30.

  On the other hand, an additive (for example, an ultraviolet absorber, a retardation increasing agent, etc.) is dissolved in a solvent, passes through a filter 12 from an additive charging pot 10 and is stocked in a stock pot 13. Then, it is mixed with the main dope by the confluence pipe 20 and the mixer 21 through the filter 15 and the conduit 16.

  The main dope liquid-fed to the pressure die 30 is cast on a metal support 31 in the form of a metal belt to form a web 32, which is peeled at a peeling position 33 after predetermined drying to obtain a film. The peeled web 32 is dried by a first drying device 34 while passing through a number of conveying rollers until a predetermined residual solvent amount is reached, and then stretched by a stretching device 35 in the longitudinal direction or the width direction. After the stretching, the second drying device 36 dries it while passing it through the transport roller 37 until it reaches a predetermined residual solvent amount, and the winding device 38 winds it into a roll.

  Hereinafter, each step will be described.

(1) Dope preparation step The cycloolefin-based copolymer, and in some cases, a retardation increasing agent, a matting agent, or other compound, in an organic solvent mainly containing a good solvent for the cycloolefin-based copolymer, in a dissolution pot. In the step of dissolving to prepare a dope while stirring, or in the step of preparing the dope as the main solution by mixing the cycloolefin copolymer solution with the retardation increasing agent, the matting agent or other compound solution is there.

  When the optical film of the present invention is produced by the solution casting method, the organic solvent useful for forming the dope is one that simultaneously dissolves the cycloolefin copolymer, the retardation increasing agent and other compounds. Is preferred.

  The following solvents are preferably used as the organic solvent used.

  Examples of the solvent used in the solution casting method include chlorine-based solvents such as chloroform and dichloromethane; aromatic solvents such as toluene, xylene, benzene, and mixed solvents thereof; methanol, ethanol, isopropanol, n-butanol, and the like. Alcohol solvents such as 2-butanol; methyl cellosolve, ethyl cellosolve, butyl cellosolve, dimethylformamide, dimethyl sulfoxide, dioxane, cyclohexanone, tetrahydrofuran, acetone, methyl ethyl ketone (MEK), ethyl acetate, diethyl ether; These solvents may be used alone or in combination of two or more.

When the solvent according to the present invention is a mixed solvent of a good solvent and a poor solvent, the good solvent is, for example, dichloromethane as a chlorine-based organic solvent, methyl acetate, ethyl acetate, amyl acetate as a non-chlorine-based organic solvent. , Acetone, methyl ethyl ketone, tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, cyclohexanone, ethyl formate, 2,2,2-trifluoroethanol, 2,2,3,3-hexafluoro-1-propanol, 1 , 3-difluoro-2-propanol, 1,1,1,3,3,3-hexafluoro-2-methyl-2-propanol, 1,1,1,3,3,3-hexafluoro-2-propanol , 2,2,3,3,3-pentafluoro-1-propanol, nitroethane, methanol, ethanol, n-propanol, is - propanol, n- butanol, sec- butanol, tert- butanol and the like, is preferably Among them, dichloromethane.
The poor solvent is preferably an alcohol solvent, and the alcohol solvent is preferably selected from methanol, ethanol and butanol from the viewpoints of improving the peelability and enabling high speed casting.

  In the present invention, in the case of a mixed solvent, it is preferable to use 55% by mass or more, more preferably 70% by mass or more, and further preferably 80% by mass or more of the good solvent with respect to the total amount of the solvent.

  Cycloolefin-based copolymer, in some cases a retardation increasing agent, to dissolve other compounds, a method carried out at normal pressure, a method carried out below the boiling point of the main solvent, a method carried out under pressure above the boiling point of the main solvent, A method performed by a cooling and melting method as described in JP-A-9-95544, JP-A-9-95557, or JP-A-9-95538, and a high pressure described in JP-A-11-21379. Various dissolution methods such as a method can be used, but a method performed at normal pressure is preferable.

  The concentration of the cycloolefin copolymer in the dope is preferably in the range of 10-40% by mass. After the compound is added to the dope during or after the dissolution to dissolve and disperse, the dope is filtered with a filter medium, defoamed, and sent to the next step by a liquid sending pump.

  Regarding the filtration of the dope, it is preferable to filter the dope with a filter medium having a leaf disk filter preferably having a 90% collection particle size of 10 to 100 times the average particle size of the fine particles. .

  In the present invention, the filter material used for filtration preferably has a small absolute filtration accuracy, but if the absolute filtration accuracy is too small, clogging of the filter material easily occurs, and the filter material must be frequently replaced. However, there is a problem of reducing productivity.

  Therefore, in the present invention, the filter medium used for the cycloolefin copolymer dope preferably has an absolute filtration accuracy of 0.008 mm or less, more preferably 0.001 to 0.008 mm, and more preferably 0.003 to 0.003 mm. A filter medium in the range of 0.006 mm is more preferable.

  There is no particular limitation on the material of the filter medium, and a normal filter medium can be used. However, a filter medium made of plastic fiber such as polypropylene or Teflon (registered trademark) or a metal filter medium such as stainless fiber may be removed. There is no and is preferable.

In the present invention, the dope flow rate during filtration is preferably 10 to 80 kg / (h · m ² ), and more preferably 20 to 60 kg / (h · m ² ). Here, if the dope flow rate during filtration is 10 kg / (h · m ² ) or more, efficient productivity is achieved, and the dope flow rate during filtration is within 80 kg / (h · m ² ). If so, the pressure applied to the filter medium becomes appropriate, and the filter medium is not damaged, which is preferable.

  The filtration pressure is preferably 3500 kPa or less, more preferably 3000 kPa or less, still more preferably 2500 kPa or less. The filtration pressure can be controlled by appropriately selecting the filtration flow rate and filtration area.

  In many cases, the main dope may contain about 10 to 50% by mass of recycled material.

  Recycled material is, for example, a finely crushed optical film, which is generated when the optical film is formed, and has both side parts cut off, or an optical film original that exceeds the specified value of the film due to scratches etc. Anti is used.

  Further, as the raw material of the resin used for preparing the dope, those obtained by pelletizing the cycloolefin copolymer and other compounds in advance can also be preferably used.

(2) Casting step (2-1) Casting of dope An endless metal support 31 that feeds the dope to the pressure die 30 through a liquid feed pump (for example, a pressurization type fixed gear pump) and infinitely transfers it. For example, it is a step of casting the dope from a pressure die slit at a casting position on a metal support such as a stainless belt or a rotating metal drum.

  The metal support in the casting step is preferably one whose surface is mirror-finished, and a stainless belt or a drum whose surface is plated with a casting is preferably used as the metal support. The cast width can be in the range of 1 to 4 m, preferably 1.3 to 3 m, and more preferably 1.5 to 2.8 m. The surface temperature of the metal support in the casting step is set in the range of -50 ° C to a temperature at which the solvent does not boil and foam, more preferably -30 to 0 ° C. A higher temperature is preferable because the drying speed of the web (the dope is cast on the casting support and the formed dope film is referred to as the web) can be increased, but if the temperature is too high, the web foams, The flatness may deteriorate. The temperature of the metal support is preferably 0 to 100 ° C, and more preferably 5 to 30 ° C. Alternatively, it is also a preferable method that the web is gelated by cooling and peeled from the drum in a state of containing a large amount of residual solvent.

  The method of controlling the temperature of the metal support is not particularly limited, but there are a method of blowing hot air or cold air and a method of bringing hot water into contact with the back side of the metal support. It is preferable to use warm water because the heat can be efficiently transferred, so that the time until the temperature of the metal support becomes constant is short. When using hot air, in consideration of the temperature drop of the web due to the latent heat of evaporation of the solvent, while using hot air above the boiling point of the solvent, while preventing foaming, there may be a case where the air temperature is higher than the target temperature. . In particular, it is preferable to change the temperature of the metal support and the temperature of the drying air during the period from casting to peeling to efficiently perform the drying.

  The temperature of the dope to be cast (cast) is preferably 20 to 35 ° C. from the viewpoint of evenness of the film flatness, drying property, additives and mat material.

  The die is preferably a pressure die capable of adjusting the slit shape of the die base portion and easily making the film thickness uniform. The pressure die includes a coat hanger die and a T die, and any of them is preferably used. The surface of the metal support is a mirror surface. Two or more pressure dies may be provided on the metal support in order to increase the film formation rate, and the dope amount may be divided and laminated.

(2-2) Solvent Evaporation Step This is a step of heating the web on the casting metal support to evaporate the solvent, and a step of controlling the residual solvent amount at the time of peeling described later.

  To evaporate the solvent, there are a method of blowing air from the web side, a method of transferring heat from the back surface of the metal support by a liquid, a method of transferring heat from the front and back sides by radiant heat, etc. It is efficient and preferable. A method of combining them is also preferably used. The web on the metal support after casting is preferably dried on the metal support in an atmosphere of 30 to 100 ° C. In order to maintain the atmosphere at 30 to 100 ° C., it is preferable to apply hot air of this temperature to the upper surface of the web or heat it by means such as infrared rays.

  From the viewpoint of surface quality, moisture permeability, and peelability, it is preferable to peel the web from the metal support within 30 to 180 seconds.

(2-3) Peeling step This is a step of peeling the web, in which the solvent is evaporated on the metal support, at the peeling position. The peeled web is sent to the next step as a film.

  The temperature at the peeling position on the metal support is preferably in the range of 10 to 40 ° C, more preferably 11 to 30 ° C.

  In the present invention, the solvent in the web is evaporated in the solvent evaporation step, but the residual solvent amount of the web on the metal support at the time of peeling is preferably in the range of 15 to 100% by mass. The amount of residual solvent is preferably controlled by the drying temperature and the drying time in the solvent evaporation step.

  When the amount of the residual solvent is 15% by mass or more, the matting agent does not have a distribution in the thickness direction and is uniformly dispersed in the film during the drying process on the metal support. It is possible to prevent deformation of the winding shape. Further, the drying time is not lengthened and the productivity is improved.

  Further, when the residual solvent amount is 100% by mass or less, the film has self-supporting property, it is possible to avoid peeling failure of the film, and the mechanical strength of the web can be maintained, so that the flatness at the time of peeling is improved, It is possible to suppress the generation of cracks and vertical stripes due to peeling tension.

  The amount of residual solvent in the web or film is defined by the following formula (Z).

Formula (Z)
Amount of residual solvent (%) = (mass before heat treatment of web or film-mass after heat treatment of web or film) / (mass after heat treatment of web or film) × 100
Note that the heat treatment for measuring the amount of residual solvent means performing heat treatment at 115 ° C. for 1 hour.

  The peeling tension when peeling the web from the metal support to form a film is usually in the range of 196 to 245 N / m, but when wrinkles are easily formed during peeling, peeling is performed with a tension of 190 N / m or less. Preferably.

  In the present invention, the temperature at the peeling position on the metal support is preferably within the range of -50 to 40 ° C, more preferably within the range of 10 to 40 ° C, and within the range of 15 to 30 ° C. Is most preferred.

(3) Drying and Stretching Step The drying step may be divided into a preliminary drying step (first drying step) and a main drying step (second drying step).

(3-1) Preliminary Drying Step The film obtained by peeling the web from the metal support is predried by the first drying device 34. The pre-drying of the film may be carried out by transporting the film with a number of rollers arranged above and below, or by carrying it while transporting by fixing both ends of the film with clips like a tenter dryer. Good.

  The means for drying the web is not particularly limited, and generally, hot air, infrared rays, a heating roller, microwaves or the like can be used, but hot air is preferable in terms of simplicity.

  The drying temperature in the pre-drying step of the web is preferably the glass transition point of the film of -5 ° C or lower, and it is effective to perform heat treatment at a temperature of 30 ° C or higher for 1 minute to 30 minutes. The drying temperature is in the range of 40 to 150 ° C, more preferably 50 to 100 ° C.

(3-2) Stretching Step The optical film of the present invention is stretched in a stretching device 35 under a residual solvent amount to improve the flatness of the film and control the orientation of molecules in the film. Thus, desired phase difference values Ro and Rt can be obtained.

  In the method for producing an optical film of the present invention, in the step of stretching the film, the residual solvent amount at the start of stretching is preferably 1% by mass or more and less than 15% by mass. More preferably, it is in the range of 2 to 10% by mass.

  The optical film of the present invention is preferably stretched in the longitudinal direction (also referred to as MD direction and casting direction) and / or in the width direction (also referred to as TD direction), and is stretched in the width direction by at least a stretching device. It is preferable to manufacture it.

  The stretching operation may be performed in multiple stages. When biaxial stretching is carried out, simultaneous biaxial stretching may be carried out or may be carried out stepwise. In this case, stepwise means that, for example, stretching in different stretching directions can be sequentially performed, or stretching in the same direction can be divided into multiple stages, and stretching in different directions can be added to any of the stages. Is also possible.

Thus, for example, the following stretching steps are possible:
・ Stretching in the longitudinal direction → Stretching in the width direction → Stretching in the longitudinal direction → Stretching in the longitudinal direction ・ Stretching in the width direction → Stretching in the width direction → Stretching in the longitudinal direction → Stretching in the longitudinal direction Simultaneous biaxial stretching Includes a case where the film is stretched in one direction and the other is contracted by relaxing the tension.

  The optical film of the present invention, when the glass transition temperature of the film is set to Tg in the longitudinal direction and / or the width direction, preferably in the width direction so that the film thickness after stretching is in a desired range, ( It is preferable to stretch in the temperature range of Tg + 5) to (Tg + 50) ° C. When the film is stretched in the above temperature range, the retardation can be easily adjusted and the stretching stress can be lowered, so that the haze becomes low. Further, it is possible to obtain an optical film which suppresses the occurrence of breakage and is excellent in flatness and colorability of the film itself. The stretching temperature is preferably in the range of (Tg + 10) to (Tg + 40) ° C.

  The glass transition temperature Tg referred to here is the midpoint glass transition temperature (Tmg) measured according to JIS K7121 (1987) by measuring at a temperature rising rate of 20 ° C./min using a commercially available differential scanning calorimeter. Is. A specific method for measuring the glass transition temperature Tg of the optical film is measured using a differential scanning calorimeter DSC220 manufactured by Seiko Instruments Inc. according to JIS K7121 (1987).

  The optical film of the present invention is preferably stretched at least in the width direction at a stretching ratio within the range of 5 to 40% with respect to the original width, and further, in the longitudinal direction and the width direction of the film, respectively. It is more preferable to stretch at a stretching ratio in the range of -40%. In particular, the stretching ratio is more preferably within the range of 10 to 30% with respect to the original width. Within the above range, not only a desired retardation value can be obtained, but also a film can be thinned, particularly when a retardation increasing agent is included. The stretching ratio in the present invention means the ratio (%) of the length or width of the film after stretching to the length or width of the film before stretching.

  The method of stretching in the longitudinal direction is not particularly limited. For example, a method in which the peripheral speed difference is applied to multiple rolls and the roll peripheral speed difference is used to stretch in the machine direction, or both ends of the web are fixed with clips or pins and the distance between the clips or pins is widened in the traveling direction. And a method of stretching in the longitudinal direction, or a method of simultaneously stretching in the longitudinal and lateral directions and stretching in both the longitudinal and lateral directions. Of course, these methods may be used in combination.

  In order to stretch in the width direction, for example, the entire drying process or a part of the process as disclosed in JP-A-62-46625 is held in the width direction with clips or pins at both width ends of the web. While drying (called a tenter method), among them, a tenter method using clips and a pin tenter method using pins are preferably used.

  When stretching in the width direction, it is preferable to stretch in the width direction of the film at a stretching speed of 250 to 500% / min from the viewpoint of improving the flatness of the film.

  When the stretching speed is 250% / min or more, the flatness is improved, and the film can be processed at a high speed, which is preferable from the viewpoint of production suitability, and when it is 500% / min or less, the film breaks. It is preferable because it can be processed without any treatment.

  A preferable stretching speed is in the range of 300 to 400% / min, and it is effective when stretching at a low magnification. The stretching speed is defined by the following formula 1.

Formula 1 Stretching speed (% / min) = [(d ₁ / d ₂ ) −1] × 100 (%) / t
(In Formula 1, d ₁ is the width dimension of the optical film of the present invention after stretching in the stretching direction, d ₂ is the width dimension of the optical film before stretching in the stretching direction, and t is the time required for stretching. (Min).)
The optical film of the present invention can impart a desired retardation value, for example, by containing a retardation increasing agent and stretching. The in-plane retardation value Ro and the retardation value Rt in the thickness direction are measured using an automatic birefringence meter Axoscan (Axo Scan Mueller Matrix Polarimeter: manufactured by Axometrics Co., Ltd.) under an environment of 23 ° C. and 55% RH. It is possible to perform three-dimensional refractive index measurement at a wavelength of 590 nm and calculate from the obtained refractive indexes nx, ny and nz.

Formula _{(i): Ro = (n} x -n y) × d (nm)
Formula _{(ii): Rt = {(} n x + n y) / 2-n z} × d (nm)
[In the formulas (i) and (ii), n _x represents the refractive index in the direction x in which the refractive index is maximized in the in-plane direction of the film. n _y represents the refractive index in the direction y orthogonal to the direction x in the in-plane direction of the film. _nz represents the refractive index in the thickness direction z of the film. d represents the thickness (nm) of the film. ]
The retardation value of the optical film of the present invention is not particularly limited, but when Ro is in the range of 0 to 70 nm and Rt is in the range of 50 to 200 nm, it is preferably used in a VA liquid crystal display device. it can. Further, when Ro is in the range of 90 to 160 nm and Rt is in the range of 0 to 200 nm, it can be preferably used as a retardation film for a circularly polarizing plate in a display device equipped with a circularly polarizing plate.

  When the circularly polarizing plate is produced by roll-to-roll, the optical film of the present invention is preferably formed by a solution casting film forming method using the dope, and then the casting film is preferably formed in the width direction. Is obliquely stretched in the direction of 45 ± 30 °, more preferably in the direction of 45 ± 10 °, and the slow axis is 45 ± 30 ° with respect to the width direction, more preferably 45 ± 10 °, and particularly preferably. Is preferably applied in the direction of 45 ± 5 °.

  For the stretching method and stretching apparatus in the oblique direction, reference can be made to JP-A-2005-321543, JP-A-2013-120208, and JP-A-2014-194484.

  In the stretching step, holding / relaxation is usually performed after stretching. That is, in this step, it is preferable to perform a stretching step of stretching the film, a holding step of holding the film in a stretched state, and a relaxation step of relaxing in the stretching direction of the film in this order. In the holding step, the drawing at the drawing rate achieved in the drawing step is held at the drawing temperature in the drawing step. In the relaxation step, the stretching in the stretching step is held in the holding step, and then the tension for stretching is released to relax the stretching. The relaxation step may be performed at a temperature equal to or lower than the drawing temperature in the drawing step.

(3-3) Main Drying Step In the main drying step, the stretched film is heated and dried by the second drying device 36.

  Above all, in the present invention, in order to adjust the amount of the organic solvent contained in the optical film of the present invention, it is preferable to appropriately adjust the conditions of the main drying step.

  When the film is heated with hot air or the like, a means for preventing the mixing of the used hot air by installing a nozzle capable of exhausting the used hot air (air containing solvent or wet air) is also preferably used. The hot air temperature is more preferably in the range of 40 to 350 ° C. The drying time is preferably about 5 seconds to 60 minutes, more preferably 10 seconds to 30 minutes.

  The heating and drying means is not limited to hot air, and infrared rays, heating rollers, microwaves or the like can be used, for example. From the viewpoint of simplicity, it is preferable to dry the film with hot air or the like while transporting the film with the transport rollers 37 arranged in a staggered manner. The drying temperature is more preferably in the range of 40 to 350 ° C. in consideration of the amount of residual solvent, the expansion and contraction rate during transportation and the like.

  In the drying step, the film is preferably dried until the residual solvent amount is generally 0.5% by mass or less.

(4) Winding Step (4-1) Knurling After a predetermined heat treatment or cooling treatment, it is preferable to provide a slitter to cut off the end portion before winding, in order to obtain a good winding shape. Furthermore, it is preferable to perform knurling on both ends of the width.

  The knurling process can be formed by pressing a heated embossing roller against the widthwise end of the film. Fine embossments are formed on the embossing roller, and by pressing this, embossments can be formed on the film and the edges can be made bulky.

  The height of the knurling at both widthwise end portions of the optical film of the present invention is preferably 4 to 20 μm and the width is 5 to 20 mm.

  Further, in the present invention, it is preferable that the above-mentioned knurling process is provided after completion of drying in the film forming step of the film and before winding.

(4-2) Winding step This is a step of winding the film as a film after the amount of residual solvent in the film becomes 2% by mass or less. It is possible to obtain a good film.

  As a winding method, a generally used one may be used, and there are a constant torque method, a constant tension method, a taper tension method, a program tension control method with a constant internal stress, and the like, and these may be used properly.

[4] Physical properties of optical film <haze>
The optical film of the present invention preferably has a haze of less than 1%, more preferably less than 0.5%. By setting the haze to less than 1%, there is an advantage that the transparency of the film becomes higher and it becomes easier to use as a film for optical use.

  The haze value was measured at an equal interval in the width direction of the film at 10 points with a haze meter (NDH2000 manufactured by Nippon Denshoku Industries Co., Ltd.) under an environment of 23 ° C. and 50% RH, and the average value was calculated. I asked for haze.

<Equilibrium water content>
The optical film of the present invention, 25 ° C., the equilibrium moisture content at a relative humidity of 60% Ri der 4% or less, more preferably 3% or less. By setting the equilibrium water content to 4% or less, it is easy to respond to changes in humidity, and it is more difficult for optical characteristics and dimensions to change, which is preferable.

  The equilibrium water content is determined by leaving the sample film in a room conditioned at 23 ° C. and a relative humidity of 20% for 4 hours or more, and then in a room conditioned at 23 ° C. 80% RH for 24 hours. Using a meter (for example, CA-20 type manufactured by Mitsubishi Chemical Analytech Co., Ltd.), water is dried and vaporized at a temperature of 150 ° C., and then quantified by the Karl Fischer method.

<Film length, width, film thickness>
The optical film of the present invention preferably has a long length, specifically, a length of about 100 to 10,000 m, and is wound into a roll. The width of the optical film of the present invention is preferably 1 m or more, more preferably 1.3 m or more, and particularly preferably 1.3 to 4 m.

  The film thickness of the stretched film is preferably in the range of 10 to 50 μm from the viewpoint of thinning the display device and productivity. When the film thickness is 10 μm or more, it is possible to exhibit a film strength or retardation of a certain level or more. When the film thickness is 50 μm or less, it has a desired retardation and can be applied to thinning the polarizing plate and the display device. Preferably, the thickness of the film is in the range 15-35 μm.

[5] Application of Optical Film The optical film of the present invention is preferably a functional film used for various display devices such as liquid crystal display devices and organic EL display devices and touch panels. Specifically, the optical film of the present invention is a polarizing plate protective film for a liquid crystal display device or an organic EL display device, a retardation film, an antireflection film, a brightness enhancement film, a hard coat film, an antiglare film, an antistatic film. , An optical compensation film for expanding the viewing angle, etc. Typically, the optical film of the present invention is a polarizing plate protective film. The optical film of the present invention can also be used as a polarizing plate protective film that doubles as the retardation film.

  Further, the optical film of the present invention is suitable for a display device in which the radius of curvature of the display portion of the display device is in the range of 1 to 5000 mm. In a curved surface display device having a radius of curvature of preferably 5 to 4500 mm, a good display unevenness improving effect can be obtained.

  A curved surface display device having a radius of curvature of less than 1 mm may not be able to obtain a sufficient effect. Further, in a curved display device having a radius of curvature of more than 5000 mm, even a conventional optical film and a polarizing plate using the same, which have been used in a conventional flat display device, are notable for display unevenness. However, depending on the user or application, it is presumed that the display quality at that level can be used.

[5.1] Polarizing Plate [5.1.1] Polarizer A polarizer is an element that allows only light having a polarization plane in a certain direction to pass therethrough, and examples thereof include a polyvinyl alcohol-based polarizing film.

  As the polyvinyl alcohol-based polarizing film, there are a polyvinyl alcohol-based film dyed with iodine and a polyvinyl alcohol-based film dyed with a dichroic dye.

  The polarizer can be obtained by uniaxially stretching a polyvinyl alcohol film, followed by dyeing, or by dyeing a polyvinyl alcohol film, then uniaxially stretching, and preferably further subjected to a durability treatment with a boron compound.

  The film thickness of the polarizer is preferably in the range of 5 to 30 μm, and more preferably in the range of 5 to 15 μm.

  As the polyvinyl alcohol film, the content of ethylene units described in JP-A-2003-248123 and JP-A-2003-342322 is 1 to 4 mol%, the degree of polymerization is 2000 to 4000, and the degree of saponification is 99.0 to 99. An ethylene-modified polyvinyl alcohol of .99 mol% is preferably used. In addition, it is preferable that a polarizer is produced by the method described in JP 2011-100161 A, JP 4691205 A, and JP 4804589 A, and a polarizer is produced by bonding the polarizer to the optics of the present invention.

[5.1.2] Adhesive [Water glue]
In the polarizing plate of the present invention, it is preferable that the optical film of the present invention is attached to a polarizer using a completely saponified polyvinyl alcohol aqueous solution (water glue). Another polarizing plate protective film can be attached to the other surface. When the optical film of the present invention is used as a liquid crystal display device, it is preferably provided on the liquid crystal cell side of the polarizer, and the film outside the polarizer is the optical film of the present invention and a conventional polarizing plate protective film. Either can be used.

  For example, the conventional polarizing plate protective film, commercially available cellulose ester film (for example, Konica Minolta TAC KC8UX, KC5UX, KC8UCR3, KC8UCR4, KC8UCR5, KC8UY, KC6UY, KC6UA, KC4UY, KC4UE, KC8UE, KC8UY-HA, KC8UX- RHA, KC8UXW-RHA-C, KC8UXW-RHA-NC, KC4UXW-RHA-NC, manufactured by Konica Minolta Co., Ltd. are preferably used.

[Active energy ray curable adhesive]
Further, in the polarizing plate of the present invention, it is preferable that the optical film of the present invention and the polarizer are attached to each other with an active energy ray-curable adhesive.

  As the active energy ray curable adhesive, it is preferable to use the ultraviolet curable adhesive described below.

  In the present invention, a polarizing plate having high strength and excellent flatness can be obtained even if it is a thin film, by applying an ultraviolet-curable adhesive for bonding the optical film and the polarizer.

<Composition of UV curable adhesive>
As the ultraviolet curable adhesive composition for a polarizing plate, a photoradical polymerization type composition utilizing photoradical polymerization, a photocationic polymerization type composition utilizing photocationic polymerization, and a combination of photoradical polymerization and photocationic polymerization are used. Hybrid type compositions are known.

  The radical photopolymerizable composition contains a radical polymerizable compound containing a polar group such as a hydroxy group or a carboxy group and a radical polymerizable compound containing no polar group described in JP-A-2008-009329 in a specific ratio. Composition) and the like are known. Particularly, the radically polymerizable compound is preferably a compound having a radically polymerizable ethylenically unsaturated bond. Preferred examples of the compound having a radically polymerizable ethylenic unsaturated bond include a compound having a (meth) acryloyl group. Examples of the compound having a (meth) acryloyl group include N-substituted (meth) acrylamide compounds and (meth) acrylate compounds. (Meth) acrylamide means acrylamide or methacrylamide.

  Further, as the cationic photopolymerization type composition, (α) cationically polymerizable compound, (β) photocationic polymerization initiator, and (γ) wavelength longer than 380 nm as disclosed in JP 2011-028234A. An ultraviolet-curable adhesive composition containing each component of the photosensitizer that exhibits maximum absorption for light and (δ) naphthalene-based photosensitization aid. However, other UV curable adhesives may be used.

(1) Pretreatment Step The pretreatment step is a step of subjecting the adhesive surface of the optical film to the polarizer to an easy adhesion treatment. Examples of the easy-adhesion treatment include corona treatment and plasma treatment.

(Application process of UV curable adhesive)
In the step of applying the ultraviolet curable adhesive, the ultraviolet curable adhesive is applied to at least one of the bonding surfaces of the polarizer and the optical film. When the ultraviolet curable adhesive is applied directly to the surface of the polarizer or the optical film, the application method is not particularly limited. For example, various wet coating methods such as doctor blade, wire bar, die coater, comma coater and gravure coater can be used. Alternatively, a method in which an ultraviolet-curable adhesive is cast between the polarizer and the optical film and then pressed by a roller or the like to uniformly spread it can be used.

(2) Bonding Step After applying the ultraviolet-curable adhesive by the above method, it is processed in the bonding step. In this laminating step, for example, when the surface of the polarizer is coated with the ultraviolet curable adhesive in the previous coating step, the optical film is superposed thereon. Further, in the case of a method in which an ultraviolet curable adhesive is first applied to the surface of the optical film, the polarizer is superposed thereon. Further, when the ultraviolet curable adhesive is cast between the polarizer and the optical film, the polarizer and the optical film are superposed in that state. Then, normally, in this state, pressure is applied from both sides of the optical film by sandwiching it with a pressure roller or the like. The pressure roller can be made of metal, rubber, or the like. The pressure rollers arranged on both sides may be made of the same material or different materials.

(3) Curing Step In the curing step, the uncured ultraviolet curable adhesive is irradiated with ultraviolet rays to generate a cationically polymerizable compound (eg, epoxy compound or oxetane compound) or a radically polymerizable compound (eg, acrylate compound, acrylamide). The ultraviolet curable adhesive layer containing a compound or the like) is cured, and the laminated polarizer and the optical film are adhered via the ultraviolet curable adhesive. When the optical film is attached to one surface of the polarizer, the active energy ray may be irradiated from either the polarizer side or the optical film side. When the optical films are attached to both sides of the polarizer, the optical films are superposed on both sides of the polarizer with the ultraviolet-curing adhesives interposed therebetween, and the ultraviolet rays are irradiated to the ultraviolet-curing adhesives on both sides. It is advantageous to cure the two simultaneously.

Any appropriate conditions can be adopted as the ultraviolet irradiation conditions as long as they can cure the ultraviolet curable adhesive applied to the present invention. Preferably the dose of ultraviolet rays in the range of 50~1500mJ / cm ² in accumulated light quantity, and even more preferably in the range of 100 to 500 mJ / cm ^2.

  When the production process of the polarizing plate is performed in a continuous line, the line speed depends on the curing time of the adhesive, but is preferably in the range of 1 to 500 m / min, more preferably 5 to 300 m / min, and further preferably 10 It is in the range of 100 m / min. When the line speed is 1 m / min or more, productivity can be secured, or damage to the optical film can be suppressed, and a polarizing plate with excellent durability can be manufactured. If the line speed is 500 m / min or less, the ultraviolet curable adhesive will be sufficiently cured, and the ultraviolet curable adhesive layer having the desired hardness and excellent adhesiveness can be formed.

[5.1.3]
The film arranged on the opposite side of the polarizer from the optical film of the present invention is preferably a film which functions as a protective film for the polarizer.

  As such a protective film, the optical film of the present invention may be used. For example, a commercially available cellulose ester film (for example, Konica Minolta Tuck KC8UX, KC5UX, KC4UX, KC8UCR3, KC4SR, KC4BR, KC4CR, KC4DR, KC4FR). , KC4KR, KC8UY, KC6UY, KC4UY, KC4UE, KC8UE, KC8UY-HA, KC2UA, KC4UA, KC6UAKC, 2UAH, KC4UAH, KC6UAH, or Konica Minolta Co., FUJITAC T40UZ, FUJITAC T60UZ, FUJITAC T80UZ, FUJITAC TD80UL, Fujitac TD60UL, FUJI TAC TD40UL, FUJI TAC R02, FUJI TAC R06, manufactured by Fuji Film Co., Ltd. are also preferably used. Can.

  In addition, for example, resin films such as polyethylene terephthalate, polyethylene naphthalate, and polycarbonate, alicyclic polyolefins (for example, Zeonor (registered trademark) manufactured by Nippon Zeon Co., Ltd., polyarylate, polyether sulfone, polysulfone, cycloolefin copolymer, polyimide ( For example, resin films made of Mitsubishi Gas Chemical Co., Inc., Neoprim (registered trademark), fluorene ring-modified polycarbonate, alicyclic-modified polycarbonate, acryloyl compound and the like can be mentioned (the glass transition temperature Tg is shown in parentheses). Among the materials, in terms of cost and availability, polyethylene terephthalate (abbreviation: PET), polybutylene terephthalate, polyethylene naphthalate (abbreviation: PEN), polycarbonate (abbreviation: PC), etc. Film preferably used as the resin base material flexibility.

  The thickness of the protective film B is not particularly limited, but may be about 10 to 200 μm, preferably 10 to 100 μm, and more preferably 10 to 70 μm.

[5.2] Liquid crystal display device By using the polarizing plate to which the optical film of the present invention is attached for a liquid crystal display device, various liquid crystal display devices of the present invention having excellent visibility can be manufactured.

  The polarizing plate of the present invention can be used in liquid crystal display devices of various drive systems such as STN, TN, OCB, HAN, VA (MVA, PVA), IPS, OCB. Preferred are a VA (MVA, PVA) type liquid crystal display device and an IPS type liquid crystal display device.

  A liquid crystal display device usually uses two polarizing plates, a polarizing plate on the viewing side and a polarizing plate on the backlight side, but it is also preferable to use the polarizing plate of the present invention as both polarizing plates, and one polarizing plate. It is also preferable to use In particular, the polarizing plate of the present invention is preferably used as a polarizing plate on the visible side that directly contacts the external environment, and in that case, when the optical film of the present invention is an optical compensation film, it may be arranged on the liquid crystal cell side. preferable.

  Further, the polarizing plate on the backlight side may be a polarizing plate other than the present invention, and in this case, both surfaces of the polarizer are, for example, commercially available cellulose ester films (for example, Konica Minolta Tuck KC8UX, KC5UX, KC4UX, KC8UCR3, KC4SR, KC4BR, KC4CR, KC4DR, KC4FR, KC4KR, KC8UY, KC6UY, KC4UY, KC4UE, KC8UE, KC8UY-HA, KC2UA, KC4UA, KC6UA, KC2UAH, KC4UAH, KC6UAH, or Konica Minolta Co., FUJITAC T40UZ, FUJITAC Fujifilm Co., Ltd. T60UZ, Fujitac T80UZ, Fujitac TD80UL, Fujitac TD60UL, Fujitac TD40UL, Fujitac R02, Fujitac R06 Polarizing plate stuck etc.) is preferably used.

  Further, as the polarizing plate on the backlight side, the optical film of the present invention is used on the liquid crystal cell side of the polarizer, and the commercially available protective film or retardation film, polyester film, acrylic film, polycarbonate film, or on the opposite surface. A polarizing plate laminated with a cycloolefin polymer film can also be preferably used.

  By using the polarizing plate of the present invention, it is possible to obtain a liquid crystal display device having excellent visibility such as display unevenness and front contrast even when the liquid crystal display device has a large screen of 30 inches or more.

[5.3] Organic electroluminescence display device The optical film using the cycloolefin-based copolymer of the present invention is suitable for an organic electroluminescence display device having a curved shape.

  Regarding the outline of the organic EL element applicable to the organic electroluminescence display device used in the present invention, for example, JP 2013-157634 A, JP 2013-168552 A, JP 2013-177361 A, JP 2013-187211, JP2013-191644A, JP2013-191804A, JP2013-225678A, JP2013-235994A, JP2013-243234A, JP2013-2013A. No. 243236, No. 2013-242366, No. 2013-243371, No. 2013-245179, No. 2014-003249, No. 2014-003299, No. 2014-013910. Japanese Patent Laid-Open No. 2014-01 493 JP include a configuration described in JP-2014-017494 Patent Publication.

  Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In the examples, “part” or “%” is used, but unless otherwise specified, “part by mass” or “% by mass” is indicated.

Example 1
<Production of optical film>
(Synthesis of Cycloolefin Copolymer 1)
A cycloolefin-based monomer having a carboxy group (Exemplified monomer No. 16) and a copolymerizable monomer (Exemplified monomer No. 45) were used in a molar ratio of 70:30 to 100 parts, and 1-hexene as a molecular weight modifier (3.6 parts). 200 parts of toluene was charged into a reaction vessel purged with nitrogen and heated to 80 ° C. To this, 0.17 parts of a toluene solution containing 1.5 mol / L of triethylaluminum ((C ₂ H ₅ ) ₃ Al) as a polymerization catalyst and tungsten hexachloride (WCl ₆ ) modified with t-butanol and methanol were modified. Then, 1.0 part of a WCl ₆ solution (concentration 0.05 mol / L) in which the molar ratio of t-butanol to methanol and tungsten was 0.35: 0.3: 1 was added, and the mixture was heated at 80 ° C. for 3 hours. A ring-opening polymerization reaction was carried out by stirring to obtain a polymer solution. The polymerization conversion rate in this polymerization reaction was 98%.

4000 parts of the obtained polymer solution was placed in an autoclave, 0.48 part of RuHCl (CO) [P (C ₆ H ₅ ) ₃ ] ₃ was added to the polymer solution, the hydrogen gas pressure was 10 MPa, and the reaction temperature was 10 MPa. The mixture was heated and stirred at 160 ° C. for 3 hours to carry out a hydrogenation reaction.

  After cooling the obtained reaction solution, the hydrogen gas was released, and the reaction solution was poured into a large amount of methanol to separate and collect a coagulated product. The recovered coagulated product was dried to obtain a cycloolefin-based copolymer 1 having a structure derived from a cycloolefin-based monomer having a carboxy group.

  The weight average molecular weight of the cycloolefin copolymer 1 was 130000 as Mw in terms of polystyrene measured by gel permeation chromatography (GPC).

Similarly, the ratio of the above-mentioned monomers added is changed so that the copolymer 2 (molar ratio 50:50), the copolymer 3 (molar ratio 10:90), the copolymer 4 (molar ratio 1:99), the copolymer Polymer 5 (molar ratio 80:20 ) was prepared.

  Also, as a comparative example, JSR's Arton G7810 was prepared.

  The weight average molecular weights of the copolymers 2 to 5 and Arton G7810 were 130000 as Mw in terms of polystyrene measured by gel permeation chromatography (GPC).

<Production of optical film 101>
(Preparation of fine particle added liquid)
Fine particles (Aerosil R812: manufactured by Nippon Aerosil Co., Ltd., primary average particle diameter: 7 nm, apparent specific gravity 50 g / L) 4 parts by mass Dichloromethane 48 parts by mass Ethanol 48 parts by mass After stirring and mixing the above with a dissolver for 50 minutes, the mixture is dispersed with Manton-Gaulin. I went.

  Furthermore, dispersion was performed using an attritor so that the particle size of the secondary particles would be a predetermined size. This was filtered through Finemet NF manufactured by Nippon Seisen Co., Ltd. to prepare a fine particle added liquid.

  Then, a main dope 1 having the following composition was prepared. First, dichloromethane was added to the pressure dissolution tank at a flow rate of 400 kg / min and ethanol was added at a flow rate of 20 kg / min. Three minutes after the start of the addition of the solvent, the cycloolefin copolymer 1 was charged into the pressure dissolution tank while stirring at a flow rate of 200 kg / min. Next, 5 minutes after the start of the solvent addition, the fine particle additive liquid was added, and this was heated to 80 ° C. and completely dissolved while stirring. The heating temperature was raised from room temperature at 5 ° C / min, dissolved in 30 minutes, and then lowered at 3 ° C / min.

The dope viscosity was 10,000 CP and the water content was 0.50%. This is Azumi Filter Paper No. manufactured by Azumi Filter Paper Co., Ltd. The main dope 1 was prepared by using 244 (filtration accuracy 0.005 mm) at a filtration flow rate of 300 L / m ² · h and a filtration pressure of 1.0 × 10 ⁶ Pa.

<Composition of main dope 1>
Cycloolefin copolymer 1 100 parts by mass Dichloromethane 200 parts by mass Ethanol 10 parts by mass Fine particle additive liquid 15 parts by mass Then, using an endless belt casting device, the above dope was heated at a temperature of 33 ° C. and a stainless belt support at a width of 1.5 m. Cast evenly on top. The temperature of the stainless belt was controlled at 30 ° C.

  The solvent was evaporated on the stainless belt support until the amount of residual solvent in the cast film reached 75%, and then the film was peeled off from the stainless belt support with a peeling tension of 130 N / m.

  The peeled optical film was stretched by 35% in the casting direction between the rolls while applying heat of 140 ° C., and continuously stretched by 5% in the width direction using a tenter. The residual solvent at the start of stretching was 5% by mass. Then, the drying was completed while the drying zone was conveyed by a large number of rollers. The drying temperature was 90 ° C. and the transport tension was 100 N / m. After drying, the film was slit into a width of 1.5 m, knurled with a width of 10 mm and a height of 10 μm on both ends of the film, and wound into a roll to obtain an optical film 101 having a dry film thickness of 40 μm.

<Production of optical films 102 to 106>
Similar to the optical film 101, instead of the copolymer 1, the copolymer 2 (molar ratio 50:50), the copolymer 3 (molar ratio 10:90), the copolymer 4 (molar ratio 1:99). ), Copolymer 5 (molar ratio 80:20 ) and JSR's Arton G7810 were used respectively, and optical films 102 to 106 were produced in the same manner.

<Production of optical film 107>
An optical film 107 was produced in the same manner as the optical film 101, except that the cycloolefin-based copolymer 6 synthesized by the synthesis scheme 2 was used instead of the copolymer 1.

<Preparation of Cycloolefin Copolymer 6>
Exemplary monomer No. 45 g of the polymer A obtained by the ring-opening metathesis polymerization reaction was dissolved in 500 mL of toluene by stirring at room temperature for 1 hour, and a 10.8 mol / L NaOH aqueous solution was added thereto and heated to 80 ° C. While vigorously stirring for 12 hours (hydrolysis), the mixture was allowed to cool, and hydrochloric acid was added (acid treatment) for neutralization. After separating the organic phase and the aqueous phase, the operation of adding pure water to the organic phase and removing impurities in the organic phase is repeated twice, and the obtained organic phase is dried under reduced pressure by heating to obtain a cycloolefin system having a carboxy group. Polymer B having a structure derived from a monomer was obtained with a yield of 95%.

  The weight average molecular weight of the copolymer 6 was 130000 as Mw in terms of polystyrene measured by gel permeation chromatography (GPC).

<Measurement of carboxylic acid modification rate>
The carboxylic acid modification rate was analyzed by H-NMR according to the following procedure.

  The sample was dissolved in a deuterated chloroform solvent and H-NMR measurement was performed.

  In the polymer B as compared with the polymer A, the peak derived from the methyl group hydrogen of the ester moiety observed at around 3.6 ppm is different from the peak derived from alkyl hydrogen other than the above which appears over 0.5 to 2.5 ppm. The ratio was decreased, and the carboxylic acid-modified monomer ratio of the polymer B having a structure derived from a cycloolefin-based monomer having a carboxy group was calculated from the ratio, and it was 25%.

<< Evaluation >>
[1] Measurement of pH value of optical film As for the pH value of the optical film, "ion-exchanged water" specified in JIS K 0557 is bubbled with nitrogen gas for 15 minutes or more by a method specified in JIS K 8001: 2009, Decarbonated water was prepared under a nitrogen gas atmosphere. The entire optical film cut into 5 cm squares was immersed in 15 mL of the prepared decarbonated water having a liquid temperature of 23 ° C. for 15 minutes in a nitrogen atmosphere, and a pH electrode was placed in the solution for measurement. As the pH electrode, HM-30R manufactured by Toa DKK Co., Ltd. was used.

[2] Polarizer Adhesiveness A polarizing plate was produced using the optical films 101 to 107 produced above.

  A roll-shaped polyvinyl alcohol film having a thickness of 80 μm was continuously stretched 5 times in an aqueous iodine solution and dried to obtain a polarizer having a thickness of 20 μm.

  Then, the above-prepared polarizer is sandwiched between the above-prepared optical films 101 to 107 and Konica Minolta Tuck KC4UA (manufactured by Konica Minolta Co., Ltd.) as a polarizer protective film to obtain the following ultraviolet curable adhesive liquid. A polarizing plate was produced by adhering via the above.

  At that time, the lamination was performed so that the absorption axis of the polarizer and the slow axis of the optical film of the present invention were orthogonal to each other.

[Preparation of UV curable adhesive liquid 1]
After mixing the following components, defoaming was performed to prepare an ultraviolet curable adhesive liquid 1. The triarylsulfonium hexafluorophosphate was added as a 50% propylene carbonate solution, and the solid content of triarylsulfonium hexafluorophosphate is shown below.

3,4-Epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate 45 parts by mass Epolide GT-301 (alicyclic epoxy resin manufactured by Daicel) 40 parts by mass 1,4-butanediol diglycidyl ether 15 parts by mass Tria Reel sulfonium hexafluorophosphate 2.3 parts by mass 9,10-dibutoxyanthracene 0.1 parts by mass 1,4-diethoxynaphthalene 2.0 parts by mass It should be noted that the production of a polarizing plate was performed by corona output strength of 2. Corona discharge treatment was performed at 0 kW and a line speed of 18 m / min, and the prepared ultraviolet curable adhesive liquid 1 was applied to the corona discharge treated surface with a bar coater so that the film thickness after curing was about 3 μm. To form an ultraviolet curable adhesive layer.

The above-mentioned polarizing plate was irradiated with ultraviolet rays from the optical film side of the present invention so as to have an integrated light quantity of 750 mJ / cm ² by using an ultraviolet irradiation device with a belt conveyor (the lamp uses a D bulb manufactured by Fusion UV Systems Co., Ltd.). Irradiation was performed to cure the ultraviolet curable adhesive layer.

  100 square-shaped cuts were made on the optical film surface of the above-prepared polarizing plate so as to penetrate the film using a cutter guide having a gap of 1 mm. Next, the optical film was placed on the outside and attached to a cylinder having a diameter of 80 mm with a double-sided tape. In that state, an 18 mm tape (Cellotape (registered trademark) CT-18 manufactured by Nichiban Co., Ltd.) was attached to the cut surface on the square, and a 2.0 kg roller was reciprocated 20 times from above to remove air remaining at the interface. Pressed with an eraser to ensure complete contact. Then, the peeling angle was maintained at 180 ° C., and the peeling was performed rapidly. After peeling off, the work of attaching a new tape and peeling off was repeated 10 times in the same manner as above. The peeling rate of the optical film at that time was evaluated according to the following criteria.

⊚: Peeling area is less than 3% ◯: Peeling area is 3% or more and less than 5% ×: Peeling area is 5% or more [3] Optical unevenness Liquid crystal display device with curved display (SAMSUNG 55HU9000, radius of curvature 4200 mm) The polarizing plate was peeled off from the liquid crystal panel of 1), and the above-prepared polarizing plate was attached so that the absorption axis of the polarizing plate and the optical axis of the retardation film were in the same positions as the original positions.

  In a dark room, the appearance of display unevenness due to light leakage of the curved surface portion during black display was visually observed and evaluated according to the following criteria.

◯: No display unevenness was generated x: Display unevenness was generated As described above, Table 1 shows the configurations and evaluation results of the optical film.

  It can be seen from Table 1 that the optical films 101 to 104 and 107 of the present invention have excellent polarizer adhesion and are excellent in suppressing the occurrence of display unevenness even when mounted on a liquid crystal display device having a curved display portion. Do you get it.

  In the optical film 105 of Comparative Example, since the pH value of the film was on the acidic side, deterioration due to dye decomposition of the polarizer was observed and display unevenness was poor.

  The optical film 106 of the comparative example lacked the plasticizing effect, resulting in poor adhesion and display unevenness.

Example 2
<Preparation of optical films 201 to 207 for circularly polarizing plate>
In the production of the optical films 101 to 107 of Example 1, instead of the stretching process in the width direction, the oblique stretching method and the stretching device described in JP-A-2005-321543 are used, and And optical films 201 to 207 for circularly polarizing plates whose slow axes are oblique to the long direction with respect to the longitudinal direction are produced by making the optical films 101 to 107 respectively correspond to the optical films 101 to 107. did.

  The optical film has Ro = 140 nm and Rt = 90 nm when measured at a light wavelength of 550 nm in an environment of 23 ° C. and 55% RH by the above-described method for measuring the retardation values Ro and Rt, and is a λ / 4 plate. there were.

<Application to organic EL display device having curved surface shape>
The produced polarizer is sandwiched between the produced optical films 201 to 207 and a polarizer protective film (Konica Minolta Tuck KC4UA (manufactured by Konica Minolta Co., Ltd.)), and the ultraviolet curable adhesive liquid 1 is interposed therebetween. Then, they were laminated so that the absorption axis of the polarizer and the slow axis of the optical film were 45 ° to form a circularly polarizing plate.

  The PET film for depolarizing was peeled off from the organic EL panel of the smartphone (GALAXY NOTE EDGE: radius of curvature: 7 mm, manufactured by SAMSUNG) having a curved display, and the circular polarizing plate prepared above was attached to the obtained circular polarizing plate. It was

  When optical unevenness was evaluated in the same manner as in Example 1, the optical films 201 to 204 and 207 of the present invention reproduce Example 1 and have excellent polarizer adhesion, so that the display portion has a curved surface. It was found that even when mounted on a shaped organic EL display device, it was excellent in suppressing the occurrence of display unevenness.

  Further, the tint when the display screen was viewed through the polarized sunglasses was better when the circular polarizing plate of the present invention was used than when the original PET film was used. This is because the original PET film eliminates the polarization due to the ultra-high retardation, whereas the circularly polarizing plate of the present invention optically compensates as a λ / 4 retardation film. It has been found that the optical film of the present invention is suitable for curved surface display applications.

DESCRIPTION OF SYMBOLS 1 Melting kettle 3, 6, 12, 15 Filtration machine 4, 13 Stock kettle 2, 5, 11, 14 Liquid feed pump 8, 16 Conduit 10 Additive charging kettle 20 Combiner pipe 21 Mixer 30 Pressing die 31 Metal support 32 Web 33 Peeling Position 34 First Drying Device 35 Stretching Device 36 Second Drying Device 37 Conveying Roller 38 Winding Device 41 Charging Pot 42 Stock Pot 43 Pump 44 Filter

Claims (5)

At least an optical film containing a cycloolefin-based copolymer having a structure derived from a cycloolefin-based monomer having a carboxy group,
The cycloolefin-based monomer has a structure represented by the following general formula (a),
The pH value when a solution obtained by immersing the entire optical film cut into 5 cm squares in 15 mL of decarbonated water at a liquid temperature of 23 ° C. for 15 minutes in a nitrogen atmosphere was within the range of 5.7 to 7.3. Yes, and
An optical film having an equilibrium water content of 4% or less at 25 ° C. and 60% relative humidity.

(In the formula, p = 1, B ¹ and B ² = H, B ³ = Me, and B ⁴ = COOH.)   The copolymerization ratio of the cycloolefin-based monomer having the structure represented by the general formula (a) is in the range of 1 to 70 mol% with respect to the entire cycloolefin-based copolymer. Item 2. The optical film according to Item 1.   A polarizing plate comprising the optical film according to claim 1 or 2 disposed on at least one surface of a polarizer.   A display device comprising the polarizing plate according to claim 3.   The display device according to claim 4, wherein a radius of curvature of a display portion of the display device is within a range of 1 to 5000 mm.

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