JP2017076046A - Optical film, polarizing plate, and display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical film using a cycloolefin copolymer that is highly suitable for display on a curved surface and suppresses the occurrence of display unevenness when the optical film is made into a curved surface, and a polarizing plate and a liquid crystal display using the same.SOLUTION: An optical film of the present invention is an optical film that contains at least a cycloolefin copolymer having a structure derived from a cycloolefin monomer including a carboxy group; when the optical film is impregnated with decarbonated water at a solution temperature of 23°C for 15 minutes under nitrogen atmosphere, the pH value of a resulting liquid is measured to be in a range of 5.7 to 7.3.SELECTED DRAWING: None

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, and a polarizing plate and a display device using the optical film.

  In recent years, display applications such as liquid crystals and organic electroluminescence elements (hereinafter also referred to as organic EL elements) have been required to have curved surface display suitability as the applications expand.

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

  However, even in the retardation film using the cycloolefin-based resin in which display unevenness does not occur in the conventional flat display device, there is a problem that display unevenness occurs when arranged in a curved shape. I understood that.

  As a result of investigating the cause of the occurrence of display unevenness, by arranging the retardation film in a curved surface, local stress is generated in the retardation film, resulting in partial distortion in the film, and the polarizer and It was ascertained that this was caused by the loss of uniform adhesion of the film.

  In Patent Document 1, for the purpose of optical disc use, a cycloolefin-based resin has been studied focusing on the effect of improving the adhesion to the recording layer. However, film properties, suitability for polarizing plates, and suitability for display devices have been studied. There is no examination or suggestion about the problem when it is arranged in a curved surface. Therefore, the appearance of an optical film using a cycloolefin resin as a member of a display device that improves uniform adhesion with the polarizer when arranged in the curved surface shape and suppresses the occurrence of display unevenness is awaited. Yes.

JP 2001-187815 A

  The present invention has been made in view of the above-mentioned problems and situations, and a solution to that problem is a cycloolefin copolymer that has high curved surface display suitability and suppresses display unevenness when the optical film is curved. It is providing the optical film using this, a polarizing plate using the same, and a display apparatus.

  In order to solve the above problems, the present inventor is an optical film containing a cycloolefin copolymer having a structure derived from a cycloolefin monomer having a specific group in the process of studying the cause of the above problems. Thus, the present inventors have found that the above problems can be solved by an optical film in which the pH value of a solution obtained by immersing the film in decarbonated water is within a specific range, and the present invention has been achieved.

  That is, the said subject which concerns on this invention is solved by the following means.

  1. An optical film containing at least a cycloolefin copolymer having a structure derived from a cycloolefin monomer having a carboxy group, wherein the optical film is immersed in decarbonated water at a liquid temperature of 23 ° C. in a nitrogen atmosphere for 15 minutes. An optical film having a pH value of 5.7 to 7.3 when the measured liquid is measured.

  2. 2. The optical film as described in item 1, wherein the cycloolefin monomer has a structure represented by the following general formula (a).

（式中、Ｂ^１〜Ｂ^３は各々独立に水素原子；ハロゲン原子；酸素、窒素、イオウ若しく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。Ｂ^４はＣＯＯＨを表す。ｐは０〜２の自然数を表す。）
３．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であることを特徴とする第２項に記載の光学フィルム。

(In the formula, B ^{1 to} B ³ are each independently a hydrogen atom; a halogen atom; a substituted or unsubstituted carbon atom having 1 to 30 carbon atoms which may have a linking group containing oxygen, nitrogen, sulfur or silicon. Represents a hydrogen group; or represents a polar group, B ⁴ represents COOH, and p represents a natural number of 0 to 2.)
3. ^3. The optical film as described in item 2, wherein, in the general formula (a), p = 1, B ¹ and B ² = H, B ³ = Me and B ⁴ = COOH.

  4). The copolymerization ratio of the cycloolefin 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 copolymer. Item 2. The optical film according to item 3 or 3.

  5. A polarizing plate, wherein the optical film according to any one of items 1 to 4 is disposed on at least one surface of a polarizer.

  6). A display device comprising the polarizing plate according to Item 5.

  7). Item 7. The display device according to item 6, wherein the radius of curvature of the display unit of the display device is in the range of 1 to 5000 mm.

  An optical film using a cycloolefin copolymer that suppresses the occurrence of display unevenness when the curved surface of the optical film is highly curved by the above means of the present invention, and a polarizing plate and a display device using the same Can be provided.

  The expression mechanism or action mechanism of the effect of the present invention is not clear, but is presumed as follows.

  Although the optical film using the cycloolefin copolymer according to the present invention has low moisture permeability, it can contain a slight amount of moisture. The cycloolefin copolymer having a specific structure according to the present invention is obtained by measuring a liquid obtained by immersing an optical film containing the copolymer in decarbonated water at a liquid temperature of 23 ° C. in a nitrogen atmosphere for 15 minutes. By controlling the copolymerization ratio of the monomer having a carboxy group so as to adjust the pH value from weakly acidic to near neutral, or adjusting the content of the monomer having a carboxy group into the optical film. It is presumed that the water content can be adjusted, and as a result, the water in the film can exhibit a function similar to that of a plasticizer.

  As a result, the stress generated when the optical film is arranged in a curved shape can be relaxed inside the film, so that the uniformity of adhesion with the polarizer is improved, and optical functions such as retardation are provided. It is assumed that the occurrence of display unevenness can be suppressed without damage.

  In addition, when the pH value of the optical film is smaller than the numerical value range of the present application rule, the acidity is strong, and thus polarizer deterioration occurs in the normal durability evaluation, whereas when the pH value of the optical film is larger than the numerical value range of the present application rule. Does not exhibit a plastic effect and causes 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 for this invention, a casting process, a drying process, and a winding-up process

  The optical film of the present invention is an optical film containing at least a cycloolefin copolymer having a structure derived from a cycloolefin monomer having a carboxy group, wherein the optical film is decarboxylated at a liquid temperature of 23 ° C. The pH value when measuring a solution immersed in water for 15 minutes in a nitrogen atmosphere is in the range of 5.7 to 7.3. This feature is a technical feature common to the inventions according to claims 1 to 7.

As an embodiment of the present invention, it is preferable that the cycloolefin-based monomer has a structure represented by the general formula (a) from the viewpoint of manifesting the effects of the present invention. In the formula, P = 1, B ¹ and B ² = H, B ³ = Me and B ⁴ = COOH adjust the water content contained by controlling the pH value of the optical film to a specific range. From the viewpoint, it is preferable that the copolymerization ratio of the cycloolefin monomer having the structure is in the range of 1 to 70 mol% with respect to the entire cycloolefin copolymer, so that the effect of the present invention is exhibited. Therefore, it is a preferred embodiment.

  The optical film of the present invention can be suitably used for polarizing plates and display devices. In particular, this makes it possible to provide a display device in which the occurrence of display unevenness is suppressed even for a display device having a curved surface shape.

  Moreover, it is a preferable display apparatus when applying the optical film of this invention that the curvature radius of the display part of the said display apparatus is in the range of 1-5000 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 behind that as a lower limit and an upper limit.

<< Outline of Optical Film of the Present Invention >>
The optical film of the present invention is an optical film containing at least a cycloolefin copolymer having a structure derived from a cycloolefin monomer having a carboxy group, and the optical film is subjected to decarbonated water at a liquid temperature of 23 ° C. The pH value when measuring the liquid immersed for 15 minutes in a nitrogen atmosphere is in the range of 5.7 to 7.3.

<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” refers to “decarbonated water” prepared by the method defined in JIS K 8001: 2009 using “ion-exchanged water” or “distilled water” of type A2 or A3 defined in JIS K0557. use.
Specifically, for example, “ion-exchanged water” defined 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 a 5 cm square is immersed in 15 mL of prepared decarbonated water at 23 ° C. for 15 minutes under a nitrogen atmosphere, and a pH electrode is placed in the solution for measurement. In addition, a commercially available electrode can be used for a pH electrode, for example, HM-30R of Toa DKK Corporation can be used.

  The cycloolefin copolymer having a specific structure according to the present invention is controlled by controlling the copolymer so that the liquid in which the film containing the copolymer is immersed is adjusted from weak acidity to near neutrality. The amount of moisture contained in the optical film can be adjusted, and the moisture generated in the optical film can be reduced by reducing the stress generated when the optical film is arranged in a curved shape by exhibiting a function similar to that of a plasticizer. It is assumed that the uniformity of adhesion with the polarizer can be improved and the occurrence of display unevenness can be suppressed.

  In addition, when the pH value of the optical film is less than 5.7, the acidity is strong, and thus polarizer deterioration occurs in durability evaluation. On the other hand, when the pH value of the optical film is greater than 7.3, the plastic effect is exhibited. In this case, the pH value needs to be within the range of the present invention.

<Configuration of optical film of the present invention>
[1] Cycloolefin copolymer The cycloolefin copolymer according to the present invention is a cycloolefin copolymer having a structure derived from a cycloolefin monomer having a carboxy group. It can be obtained by adjusting the content of cycloolefin monomer having a carboxyl group.

  As the structure of the cycloolefin monomer, for example, norbornene, dicyclopentadiene, tetracyclododecene, ethyltetracyclododecene, ethylidenetetracyclododecene, tetracyclo [7.4.0.110, 13.02, 7] Unsaturated hydrocarbons having a polycyclic structure such as 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 other monocyclic unsaturated hydrocarbons and derivatives thereof Can be mentioned. These monomer structures 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 anhydride group.

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

  The cycloolefin monomer having a carboxy group according to the present invention is preferably a cycloolefin monomer having a structure represented by the following general formula (a).

（式中、Ｂ¹〜Ｂ^３は各々独立に水素原子；ハロゲン原子；酸素、窒素、イオウ若しく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。Ｂ^４はＣＯＯＨを表す。ｐは０〜２の自然数を表す。）
Ｂ¹〜Ｂ^３である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。

(Wherein B ^{1 to} B ³ are each independently a hydrogen atom; a halogen atom; a substituted or unsubstituted carbon atom having 1 to 30 carbon atoms which may have a linking group containing oxygen, nitrogen, sulfur or silicon) Represents a hydrogen group; or represents a polar group, B ⁴ represents COOH, and p represents a natural number of 0 to 2.)
Examples of the polar group that is B ^{1 to} B ³ include a hydroxy group, an alkoxycarbonyl group, an allyloxycarbonyl group, an amino group, an amide group, a cyano group, and the like. May be combined. In addition, a hydrocarbon group in which a divalent organic group having a polarity such as a carbonyl group, an ether group, a silyl ether group, a thioether group, or an imino group is bonded as a linking group can also be exemplified. Among these, a 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 solubility during solution film formation.

The cycloolefin monomer is a copolymer with other monomers in the general formula (a) such that p = 1, B ¹ and B ² = H, B ³ = Me and B ⁴ = COOH. From the viewpoint of increasing the controllability of the pH value of the optical film, the structure is preferable.

  By using a cycloolefin-based monomer in which the substituent is substituted on one side of carbon, the symmetry of the molecule is lost, or the diffusion movement of the resin during solvent volatilization is promoted, and the plastic effect due to moisture contained in the film is enhanced. It is possible to improve the function of relieving the stress generated when the optical film is arranged in a curved shape inside the film, so that the uniformity of adhesion with the polarizer can be further improved.

  Although the compound example of the cycloolefin type monomer which has a structure represented by general formula (a) is shown concretely, it is not limited at all by the following specific examples.

  Examples of the copolymerizable monomer copolymerized with the cycloolefin monomer according to the present invention include ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, Α-olefins having 2 to 20 carbon atoms such as 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene and derivatives thereof; norbornene, dicyclopentadiene, tetracyclododecene, ethyltetracyclododecene, ethylidenetetra Polycyclic unsaturated hydrocarbons such as cyclododecene, tetracyclo [7.4.0.110, 13.02,7] trideca-2,4,6,11-tetraene and derivatives thereof; cyclobutene, cyclopentene, cyclohexene 3,4-dimethylcyclopentene, 3-methylcyclohexe , 2- (2-methylbutyl) -1-cyclohexene, cyclooctene, 3a, 5,6,7a-tetrahydro-4,7-methano-1H-indene, cycloheptene, cyclopentadiene, cyclohexadiene, etc. Saturated hydrocarbons and derivatives thereof; 1,4-hexadiene, 4-methyl-1,4-hexadiene, 5-methyl-1,4-hexadiene, non-conjugated dienes such as 1,7-octadiene; and the like are used.

  Among the copolymerizable monomers, a cycloolefin monomer having a structure represented by the following general formula (b-1) and 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 General Formula (b-1), R ^{1 to} R ⁴ are each independently 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 represents 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, and 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, or an imino group is bonded as a linking group can also be exemplified. Among 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 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 General 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 amide 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), the use of a cycloolefin monomer in which the substituents R ⁵ and R ⁶ are substituted on one side carbon may cause the symmetry of the molecule to be lost or the solvent. This 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 at the time of solution film formation. It is also preferable from the viewpoint of securing the solubility of

  Although the structure of the cycloolefin type monomer which has a structure represented by general formula (b-1) and general formula (b-2) below is shown concretely, it is not limited by the following specific examples.

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

  When copolymerizing a cycloolefin monomer having a carboxy group according to the present invention and another monomer copolymerizable therewith, the copolymerization ratio of the cycloolefin monomer having a carboxylic group to the entire copolymer obtained is From the standpoint of exhibiting the effects of the present invention, it is preferably in the range of 1 to 70 mol%, more preferably in the range of 10 to 50 mol%, and is appropriately selected.

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

  Preferred cycloolefin copolymers according to the present invention include those having structural units represented by the following general formula (c-1) and general formula (c-2). Such a cycloolefin-based copolymer includes 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). The copolymer containing each structural unit of Formula (c-2) may be sufficient.

  Preferably, it is a copolymer containing only the structure of the general formula (c-2) or the structural units of both the general formula (c-1) and the general formula (c-2). The obtained cycloolefin copolymer is preferable in that it has an excellent glass transition temperature and high 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 General Formula (c-1), X is a group represented by —CH═CH— or a group represented by the formula: —CH ₂ CH ₂ —. R ^{1 to} R ³ 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, R ⁴ represents COOH P represents a natural number of 0 to 2.)

(In General Formula (c-2), X is a group represented by —CH═CH— or a group represented by the formula: —CH ₂ CH ₂ —. R ⁵ is independently a hydrogen atom, C1-C5 hydrocarbon group or alkylsilyl group having a C1-C5 alkyl group, 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.)
Regarding the detailed conditions for producing the cycloolefin copolymer according to the present invention, the description in paragraphs 0019 to 0039 of JP-A-2008-107534 can be referred to. 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 organoaluminum compound. As a catalyst for ring-opening polymerization, a polymerization catalyst comprising a metal halide such as ruthenium, rhodium, palladium, osmium, iridium, platinum, nitrate or acetylacetone compound and a reducing agent; or titanium, vanadium, zirconium, tungsten, molybdenum And a polymerization catalyst composed of a metal halide such as acetylacetone compound and an organoaluminum compound. The polymerization temperature, pressure and the like are not particularly limited, but the polymerization is usually carried out at a polymerization temperature of −50 to 100 ° C. and a polymerization pressure of 0 to 490 N / cm ² .

  Moreover, it is preferable that the cycloolefin copolymer as a film material is obtained by copolymerizing a cycloolefin monomer and then hydrogenating it to change the unsaturated bond in the molecule to a saturated bond. The hydrogenation reaction is performed by blowing hydrogen in the presence of a known hydrogenation catalyst. Hydrogenation catalysts include cobalt acetate / triethylaluminum, nickel acetylacetonate / triisobutylaluminum, transition metal compounds such as titanocene dichloride / n-butyllithium, zirconocene dichloride / sec-butyllithium, tetrabutoxytitanate / dimethylmagnesium / alkyl 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 And 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, weather resistance deterioration, etc. Preferably it is 99% or more.

  As another method, the cycloolefin copolymer according to the present invention is obtained by subjecting a cycloolefin monomer to a polymer by a normal ring-opening metathesis polymerization reaction, followed by hydrolysis and acid treatment. It can also be obtained by modifying a part of the ester to 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 by stirring in 500 mL of toluene at room temperature for 1 hour, to which 10.8 mol / L NaOH aqueous solution is added and heated to 80 ° C. While stirring vigorously for 12 hours (hydrolysis), the mixture was allowed to cool and then neutralized with hydrochloric acid (acid treatment). 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 resulting organic phase as a desiccant to remove residual moisture. Then, the desiccant was removed by filtration, and the organic phase was heated and dried under reduced pressure. As a result, the desired polymer B having a carboxy group can be obtained in 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.

  Dissolve the sample in deuterated chloroform solvent and perform H-NMR measurement.

  Compared to polymer A, in polymer B, the peak derived from the methyl group hydrogen of the ester moiety observed near 3.6 ppm is higher than the peak derived from alkyl hydrogen other than the above appearing from 0.5 to 2.5 ppm. The ratio was reduced, and the carboxylic acid-modified monomer ratio of the polymer B having a carboxy group was calculated from the ratio and found to be 25%.

The preferred molecular weight of the cycloolefin copolymer according to the present invention is 0.2 to ⁵ cm ³ / g, more preferably 0.3 to ³ cm ³ / g, particularly preferably 0.4 to 0.5 in terms of 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 12,000 to 50,000, The weight average molecular weight (Mw) is preferably in the range of 20000 to 300,000, more preferably 30000 to 250,000, particularly preferably 40000 to 200000.

  As the intrinsic viscosity [η] inh, number average molecular weight and 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 as follows. 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. . The case where Tg is 110 ° C. or higher is preferred because deformation hardly occurs due to use under high temperature conditions or secondary processing such as coating or printing.

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

  For the cycloolefin copolymer, a specific hydrocarbon resin described in, for example, JP-A-9-221577 and JP-A-10-287732, or a known one, as long as the effects of the present invention are not impaired. Thermoplastic resins, thermoplastic elastomers, rubber polymers, organic fine particles, inorganic fine particles, etc. may be blended, specific wavelength dispersing agents, sugar ester compounds, antioxidants, release accelerators, rubber particles, plasticizers In addition, additives such as ultraviolet absorbers may be included.

[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. Details of the main additives are described below.

[2.1] Matting Agent The optical film of the present invention contains a matting agent for imparting irregularities to the film surface during film formation, ensuring slipperiness, and achieving a stable winding shape. It is preferable.

  In addition, the matting agent can function in order to prevent the produced film from being scratched or having deteriorated transportability when 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, silicic acid Examples thereof include magnesium and calcium phosphate. Fine particles containing silicon are preferable in terms of low turbidity, and silicon dioxide is particularly preferable.

  The average primary particle size 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 mainly contained as secondary aggregates having a particle size in the range of 0.05 to 0.3 μm. If the particles have an average particle size in the range of 80 to 400 nm, the primary particles are not aggregated. It is also preferable that it is contained.

  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.

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

  Zirconium oxide fine particles are commercially available, for example, under the names of Aerosil R976 and R811 (manufactured by Nippon Aerosil Co., Ltd.) and can be used.

  Examples of 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 (manufactured by Toshiba Silicone Co., Ltd.) Are commercially available and can be used.

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

  In the optical film of the present invention, it is preferable that the dynamic friction coefficient of at least one surface is in the range of 0.2 to 1.0.

[2.2] Retardation increasing agent In the present application, the retardation increasing agent is 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 a cycloolefin copolymer. (Light wavelength 590 nm measurement) means the compound which has a function which shows a 1.1 times or more value compared with an unadded optical film.

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

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

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

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

  As the polyester resin, aliphatic dicarboxylic acids such as adipic acid, azelaic acid, and sebacic acid, and monocarboxylic acids such as benzoic acid, propionic acid, and butyric acid can be used without departing from the object of the present invention.

  Examples of the aliphatic diol include ethylene glycol, 1,3-propylene diol, 1,4-butanediol, 1,4-cyclohexanedimethanol, 1,6-hexanediol, and the like, 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.

  A known esterification method or transesterification method can be applied to the production of the polyester resin. Examples of polycondensation catalysts used in the production of polyester resins include known antimony compounds such as antimony trioxide and antimony pentoxide, germanium compounds such as germanium oxide, titanium compounds such as titanium acetate, and aluminum compounds such as aluminum chloride. Although it can, it is not limited to these.

  Preferred polyester resins include polyethylene terephthalate resin, polyethylene terephthalate-isophthalate copolymer resin, polyethylene-1,4-cyclohexanedimethylene-terephthalate copolymer resin, polyethylene-2,6-naphthalene dicarboxylate 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. Resin.

The intrinsic viscosity of the polyester resin (phenol / 1,1,2,2-tetrachloroethane = value measured at 25 ° C. in a 60/40 mass ratio mixed solvent) is in the range of 0.7 to 2.0 cm ³ / g. Is more preferable, and it is in the range of 0.8 to 1.5 cm ³ / g. Since the molecular weight of the polyester resin is sufficiently high when the intrinsic viscosity is 0.7 cm ³ / g or more, a molded product comprising the polyester resin composition obtained by using the polyester resin has mechanical properties necessary as a molded product. At the same time, transparency is improved. When the intrinsic viscosity is 2.0 cm ³ / g or less, the moldability is good. As other plasticizers, compounds described in the general formulas (PEI) and (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 irradiated to the polarizing plate and the display device.

  Examples of ultraviolet absorbers include oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, nickel complex compounds, and the like, but less benzotriazole compounds. Compounds are preferred. In addition, ultraviolet absorbers described in JP-A-10-182621 and JP-A-8-337574 and polymer ultraviolet absorbers 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 is excellent in the ability to absorb ultraviolet rays having a wavelength of 370 nm or less from the viewpoint of preventing deterioration of a polarizer and liquid crystal. In addition, from the viewpoint of the display properties of the liquid crystal, it is preferable that the liquid crystal display device has a characteristic that absorbs 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% by mass and more preferably in the range of 0.5 to 5.0% by mass with respect to the polymer composition. preferable.

  Benzotriazole-based UV absorbers useful in the present invention include, for example, 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 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- ( A mixture of 5-chloro-2H-benzotriazol-2-yl) phenyl] propionate can be mentioned, but is not limited thereto.

  Further, as a commercial product, “TINUVIN 109”, “TINUVIN 171”, “TINUVIN 326”, “TINUVIN 328” (above, trade name, manufactured by BASF Japan Ltd.) are preferable. Can be used.

[2.5] Antioxidant Antioxidant plays a role of delaying or preventing the base film from decomposing 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 make it contain in a film.

  As such an antioxidant, a hindered phenol compound is preferably used. For example, 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], 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-tert-butyl-4-hydroxyphenyl) propionate], octa Sil-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, hydrazine-based metal deactivators such as N, N′-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyl] hydrazine and tris (2,4-di- A phosphorus processing stabilizer such as t-butylphenyl) phosphite may be used in combination.

[3] Manufacturing method of optical film The optical film of the present invention is preferably a film manufactured by a solution casting 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 preparation step), and casting the dope onto a support to form a web (also referred to as a cast film). )), 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. Produced 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 up the obtained optical film (winding step) It is preferred that

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

  FIG. 1 is a diagram schematically showing an example of a dope preparation 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 in which the solvent and the matting agent are dispersed by the disperser passes from the charging tank 41 through the filter 44 and is stocked in the stock tank 42. On the other hand, the cycloolefin copolymer as the main dope is dissolved in the dissolving pot 1 together with the solvent, and a matting agent stored in the stock pot 42 is added and mixed as appropriate 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 merge pipe 20, mixed by the mixer 21, and fed to the pressure die 30.

  On the other hand, an additive (for example, an ultraviolet absorber, a phase difference increasing agent, etc.) is dissolved in a solvent, and is passed from the additive charging vessel 10 through the filter 12 and stocked in the stock vessel 13. After that, the main dope is mixed by the merge pipe 20 and the mixer 21 through the conduit 15 through the filter 15.

  The main dope 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, and is peeled at a peeling position 33 after predetermined drying to obtain a film. The peeled web 32 is dried until it reaches a predetermined residual solvent amount while passing through a number of conveying rollers in the first drying device 34, and then stretched in the longitudinal direction or the width direction by the stretching device 35. After the stretching, the film is dried while passing through the conveying roller 37 until it reaches a predetermined residual solvent amount by the second drying device 36, and is wound into a roll by the winding device 38.

  Hereinafter, each step will be described.

(1) Dope preparation step In an organic solvent mainly composed of a good solvent for the cycloolefin copolymer, the cycloolefin copolymer, and optionally a phase difference increasing agent, matting agent or other compound in a dissolving kettle. In the step of dissolving with stirring to prepare a dope, or in the step of preparing a dope which is a main solution by mixing the cycloolefin copolymer solution with the retardation increasing agent, matting agent or other compound solution. is there.

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

  As the organic solvent used, the following solvents are preferably used.

  Examples of the solvent used in the solution casting method include chlorinated solvents such as chloroform and dichloromethane; aromatic solvents such as toluene, xylene, benzene, and mixed solvents thereof; methanol, ethanol, isopropanol, n-butanol, Examples include 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, and 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 chlorinated organic solvent, methyl acetate, ethyl acetate, or amyl acetate as a non-chlorine 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 viewpoint of improving peelability and enabling high-speed casting.

  In the present invention, if the solvent is a mixed solvent, the good solvent is preferably used in an amount of 55% by mass or more, more preferably 70% by mass or more, still more preferably 80% by mass or more based on the total amount of the solvent.

  For dissolving a cycloolefin copolymer, in some cases a retardation increasing agent, other compounds, a method performed at normal pressure, a method performed below the boiling point of the main solvent, a method performed under pressure above the boiling point of the main solvent, A method using a cooling dissolution 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.

  It is preferable that the density | concentration of the cycloolefin type copolymer in dope is the range of 10-40 mass%. After the compound is added to the dope during or after dissolution and dissolved and dispersed, it is filtered through a filter medium, defoamed, and sent to the next step with a liquid feed pump.

  For dope filtration, it is preferable to filter the dope with a filter medium having a collection particle diameter of 90%, for example, 10 to 100 times the average particle diameter of the fine particles, preferably with a main filter 3 having a leaf disk filter. .

  In the present invention, the filter medium used for filtration preferably has a low absolute filtration accuracy. However, if the absolute filtration accuracy is too small, the filter medium is likely to be clogged, and the filter medium must be frequently replaced. There is a problem of lowering 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 in the range of 0.001 to 0.008 mm, and 0.003 to 0.003. A filter medium in the range of 0.006 mm is more preferable.

  There are no particular restrictions on the material of the filter medium, and normal filter media can be used. However, plastic fiber filter media such as polypropylene and Teflon (registered trademark), and metal filter media such as stainless steel fibers are used to remove fibers. This is preferable.

In the present invention, the dope flow rate during filtration is preferably 10 to 80 kg / (h · m ² ), more preferably 20 to 60 kg / (h · m ² ). Here, if the flow rate of the dope at the time of filtration is 10 kg / (h · m ² ) or more, it becomes efficient productivity, and the flow rate of the dope at the time of filtration is within 80 kg / (h · m ² ). If so, the pressure applied to the filter medium is 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, and even more preferably 2500 kPa or less. The filtration pressure can be controlled by appropriately selecting the filtration flow rate and the filtration area.

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

  The return material is, for example, a finely pulverized optical film, which is generated when the optical film is formed, and is obtained by cutting off both sides of the film, or an optical film original that exceeds the specified value of the film due to scratches, etc. Anti is used.

  Moreover, as a raw material of resin used for dope preparation, what pelletized the cycloolefin type copolymer and other compounds previously can be used preferably.

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

  The metal support in the casting (casting) step preferably has a mirror-finished surface, and a stainless steel 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 1-4 m, preferably in the range of 1.3-3 m, more preferably in the range of 1.5-2.8 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 boils and does not foam, more preferably in the range of −30 to 0 ° C. A higher temperature is preferable because the web (the dope is cast on a casting support and the formed dope film is called a web) can be dried at a high speed, but if the temperature is too high, the web foams, The flatness may deteriorate. A preferable metal support temperature is appropriately determined at 0 to 100 ° C, and more preferably 5 to 30 ° C. Alternatively, it is also a preferable method that the web is gelled by cooling and peeled from the drum in a state containing a large amount of residual solvent.

  The method for controlling the temperature of the metal support is not particularly limited, and there are a method of blowing warm air or cold air, and a method of contacting hot water with the back side of the metal support. It is preferable to use warm water because heat transfer is performed efficiently, so that the time until the temperature of the metal support becomes constant is short. When using warm air, considering the temperature drop of the web due to the latent heat of vaporization of the solvent, while using warm air above the boiling point of the solvent, there may be cases where wind at a temperature higher than the target temperature is used while preventing foaming. . In particular, it is preferable to efficiently dry by changing the temperature of the metal support and the temperature of the drying air during the period from casting to peeling.

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

  The die is preferably a pressure die that can adjust the slit shape of the die portion of the die and easily make the film thickness uniform. Examples of the pressure die include 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. In order to increase the film forming speed, two or more pressure dies may be provided on the metal support, and the dope amount may be divided and laminated.

(2-2) Solvent evaporation process It is the process of heating a web on the metal support body for casting, and evaporating a solvent.

  To evaporate the solvent, there are a method of blowing air from the web side, a method of transferring heat from the back side of the metal support by a liquid, a method of transferring heat from the front and back by radiant heat, and the like. High efficiency 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 at this temperature to the upper surface of the web or heat 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 where the solvent has evaporated on the metal support at the peeling position. The peeled web is sent to the next process 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 in the range of 11 to 30 ° C.

  In this invention, although the solvent in a web is evaporated in the said solvent evaporation process, it is preferable that the residual solvent amount of the web on the metal support body in the time of peeling shall be in the range of 15-100 mass%. The residual solvent amount is preferably controlled by the drying temperature and drying time in the solvent evaporation step.

  When the residual solvent amount 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 in the drying process on the metal support. It is easy to suppress the deformation of the winding shape. Also, the drying time is not lengthened and productivity is improved.

  Further, if the amount of the residual solvent is within 100% by mass, the film has self-supporting properties, can avoid poor peeling of the film, and can maintain the mechanical strength of the web, so that the flatness at the time of peeling is improved, Generation of slippage and vertical stripes due to peeling tension can be suppressed.

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

Formula (Z)
Residual solvent amount (%) = (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 residual solvent amount represents 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. However, if wrinkles easily occur during peeling, the peeling tension is 190 N / m or less. It is preferable to do.

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

(3) Drying and stretching step The drying step can be divided into a preliminary drying step (first drying step) and a main drying step (second drying step).

(3-1) Pre-drying step The film obtained by peeling the web from the metal support is pre-dried by the first drying device 34. Preliminary drying of the film may be performed while the film is being transported by a number of rollers arranged above and below, or may be dried while being transported 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 can be generally performed with hot air, infrared rays, a heating roller, microwaves, or the like, but it is preferably performed with hot air in terms of simplicity.

  The drying temperature in the web pre-drying step is preferably a 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 or longer and 30 minutes or shorter. Drying is carried out at a drying temperature in the range of 40 to 150 ° C, more preferably in the range of 50 to 100 ° C.

(3-2) Stretching process The optical film of the present invention is subjected to stretching treatment under the residual solvent amount by the stretching device 35, thereby improving the flatness of the film or controlling 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 exists in the range of 2-10 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 lateral direction (also referred to as TD direction), and at least stretched in the lateral direction by a stretching device. It is preferable to manufacture it.

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

Thus, for example, the following stretching steps are possible:
-Stretch in the longitudinal direction-> Stretch in the width direction-> Stretch in the longitudinal direction-> Stretch in the longitudinal direction-Stretch in the width direction-> Stretch in the width direction-> Stretch in the longitudinal direction-> Stretch in the longitudinal direction Includes stretching in one direction and contracting the other while relaxing the tension.

  The optical film of the present invention has a glass transition temperature Tg of the film 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 a temperature range of Tg + 5) to (Tg + 50) ° C. When stretched in the above temperature range, the retardation can be easily adjusted, and the stretching stress can be reduced, so that the haze is lowered. Moreover, generation | occurrence | production of a fracture | rupture is suppressed and the optical film excellent in planarity and the coloring property of the film itself is obtained. The stretching temperature is preferably in the range of (Tg + 10) to (Tg + 40) ° C.

  In addition, the glass transition temperature Tg here is measured at a temperature rising rate of 20 ° C./min using a commercially available differential scanning calorimeter, and is determined at an intermediate glass transition temperature (Tmg) determined according to JIS K7121 (1987). It 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).

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

  There is no particular limitation on the method of stretching in the longitudinal direction. For example, a method in which a difference in peripheral speed is applied to a plurality of rolls, and the roll peripheral speed difference is used to stretch in the longitudinal direction, the both ends of the web are fixed with clips and pins, and the interval between the clips and pins is increased in the traveling direction. And a method of stretching in the longitudinal direction or a method of stretching in the longitudinal and lateral directions at the same time in 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 shown in Japanese Patent Application Laid-Open No. 62-46625 is held in the width direction by holding the width ends of the web with clips or pins. A method of drying while drying (called a tenter method), among them, a tenter method using a clip and a pin tenter method using a pin are preferably used.

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

  If the stretching speed is 250% / min or more, the planarity is improved and the film can be processed at a high speed, which is preferable from the viewpoint of production aptitude, and if it is within 500% / min, the film is broken. Can be processed without any problem.

  A preferable stretching speed is in a range of 300 to 400% / min, and is effective at the time of 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 in the stretching direction of the optical film of the present invention after stretching, d ₂ is the width dimension in the stretching direction of the optical film before stretching, and t is the time required for stretching. (Min).)
The optical film of the present invention contains a retardation increasing agent, for example, and can give a desired retardation value by stretching. The in-plane retardation value Ro and the thickness direction retardation value Rt were measured using an automatic birefringence meter Axoscan (Axo Scan Mueller Matrix Polarimeter: manufactured by Axometrics) in an environment of 23 ° C. and 55% RH. A three-dimensional refractive index measurement is performed at a wavelength of 590 nm, and the refractive indexes nx, ny, and nz obtained can be calculated.

Formula _{(i): Ro = (n} x -n y) × d (nm)
Formula (ii): Rt = {(n _x + n _y ) / 2−n _z } × d (nm)
In [Equation (i) and Formula (ii), n _x represents a refractive index in the direction x in which the refractive index is maximized in the plane direction of the film. n _y, in-plane direction of the film, the refractive index in the direction y perpendicular to the direction x. _nz represents the refractive index in the thickness direction z of the film. d represents the thickness (nm) of the film. ]
Although the retardation value of the optical film of the present invention is not particularly limited, when the Ro is in the range of 0 to 70 nm and the Rt is in the range of 50 to 200 nm, it is preferably used for the 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 provided with the circularly polarizing plate.

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

  JP, 2005-321543, JP, 2013-120208, and JP, 2014-194484, A can be referred to for the method and apparatus for extending in the slanting direction.

  In the stretching step, usually, after stretching, holding and relaxation are performed. That is, in this step, it is preferable to perform a stretching step for stretching the film, a holding step for holding the film in a stretched state, and a relaxation step for relaxing the film in the stretched direction 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 stage, the stretching in the stretching stage is held in the holding stage, and then the stretching is relaxed by releasing the tension for stretching. The relaxation step may be performed at a temperature lower than the stretching temperature in the stretching step.

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

  Especially in this invention, in order to adjust the amount of organic solvents to contain in the optical film of this invention, it is preferable to adjust suitably the conditions of this drying process.

  When the film is heated with hot air or the like, a means for preventing the mixing of used hot air by installing a nozzle that can exhaust 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.

  Further, the heating and drying means is not limited to hot air, and for example, infrared rays, heating rollers, microwaves, and the like can be used. From the viewpoint of simplicity, it is preferable to dry 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 residual solvent amount, the expansion / contraction rate in conveyance, and the like.

  In the drying step, it is preferable to dry the film until the residual solvent amount is generally 0.5% by mass or less.

(4) Winding step (4-1) Knurling processing It is preferable to provide a slitter after the predetermined heat treatment or cooling treatment and cut off the end portion before winding to obtain a good winding shape. Furthermore, it is preferable to knurling both ends of the width.

  The knurling process can be formed by pressing a heated embossing roller against the film width end. Fine embossing is formed on the embossing roller, and by pressing the embossing roller, unevenness can be formed on the film and the end can be made bulky.

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

  In the present invention, the knurling process is preferably provided after the drying in the film forming step and before the winding.

(4-2) Winding step This is a step of winding the film as a film after the residual solvent amount in the film is 2% by mass or less, and the dimensional stability is preferably set to 0.4% by mass or less. Can be obtained.

  As a winding method, a generally used method 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.

[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 applications.

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

<Equilibrium moisture content>
In the optical film of the present invention, the equilibrium water content at 25 ° C. and 60% relative humidity is preferably 4% or less, more preferably 3% or less. By setting the equilibrium moisture content to 4% or less, it is preferable to easily cope with a change in humidity and to hardly change the optical characteristics and dimensions.

  Equilibrium moisture content is determined by leaving the sample film in a room conditioned at 23 ° C. and 20% relative humidity for 4 hours or more and then leaving it in a room conditioned at 23 ° C. and 80% RH for 24 hours. Using a meter (for example, CA-20 model manufactured by Mitsubishi Chemical Analytech Co., Ltd.), moisture 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 is preferably long, specifically, preferably has a length of about 100 to 10,000 m, and is wound up in a roll shape. 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. If the film thickness is 10 μm or more, a certain level of film strength and retardation can be expressed. When the film thickness is 50 μm or less, the film has a desired retardation and can be applied to make the polarizing plate and the display device thinner. Preferably, the film thickness is in the range of 15 to 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 includes a polarizing plate protective film, a retardation film, an antireflection film, a brightness enhancement film, a hard coat film, an antiglare film, and an antistatic film for a liquid crystal display device or an organic EL display device. Or an optical compensation film for widening the viewing angle. 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 also serves as the retardation film.

  Moreover, the optical film of this invention is suitable for the display apparatus whose curvature radius of the display part of a display apparatus exists in the range of 1-5000 mm. In a curved display device having a curvature radius of preferably 5 to 4500 mm, a good display unevenness improvement effect can be obtained.

  A curved surface display device having a curvature radius 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 larger than 5000 mm, even in a conventional optical film and a polarizing plate using the same used in a conventional flat display device, display unevenness is significantly deteriorated. However, depending on the user and application, it is assumed that the display quality can be used even at that level.

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

  The polyvinyl alcohol polarizing film includes those obtained by dyeing iodine on a polyvinyl alcohol film and those obtained by dyeing a dichroic dye.

  The polarizer can be obtained by uniaxially stretching a polyvinyl alcohol film and then dyeing or dyeing the polyvinyl alcohol film, and then uniaxially stretching, and preferably by further performing 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.

  Examples of the polyvinyl alcohol film include ethylene unit content of 1 to 4 mol%, polymerization degree of 2000 to 4000, and saponification degree of 99.0 to 99 described in JP2003-248123A, JP2003-342322A, and the like. 99 mol% ethylene-modified polyvinyl alcohol is preferably used. Moreover, it is preferable to produce a polarizing plate by producing a polarizer by the method described in JP 2011-1000016 A, JP 4691205 A, and JP 4804589 A, and laminating it with the optics of the present invention.

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

  For example, as a conventional polarizing plate protective film, a commercially available cellulose ester film (for example, Konica Minoltak KC8UX, KC5UX, KC8UCR3, KC8UCR4, KC8UCR5, KC8UY, KC6UY, KC6UA, KC4UY, KC4UE, KC8UE, KC8UE, KC8UE, KC8UE, KC8UE, RHA, KC8UXW-RHA-C, KC8UXW-RHA-NC, KC4UXW-RHA-NC, manufactured by Konica Minolta, Inc.) are preferably used.

[Active energy ray curable adhesive]
Moreover, in the polarizing plate of this invention, it is preferable that the optical film and polarizer of this invention are bonded by the active energy ray hardening adhesive.

  As the active energy ray curable adhesive, the following ultraviolet curable adhesive is preferably used.

  In the present invention, by applying an ultraviolet curable adhesive to the bonding of the optical film and the polarizer, it is possible to obtain a polarizing plate having high strength and excellent planarity even in a thin film.

<Composition of UV curable adhesive>
As the UV curable adhesive composition for polarizing plates, a photo radical polymerization composition using photo radical polymerization, a photo cation polymerization composition using photo cation polymerization, and photo radical polymerization and photo cation polymerization are used in combination. Hybrid type compositions are known.

  As a radical photopolymerization type composition, a radical polymerizable compound containing a polar group such as a hydroxy group or a carboxy group described in JP-A-2008-009329 and a radical polymerizable compound not containing a polar group are contained in a specific ratio. Composition) and the like are known. In particular, the radical polymerizable compound is preferably a compound having a radical polymerizable ethylenically unsaturated bond. Preferable examples of the compound having an ethylenically unsaturated bond capable of radical polymerization include a compound having a (meth) acryloyl group. Examples of the compound having a (meth) acryloyl group include an N-substituted (meth) acrylamide compound and a (meth) acrylate compound. (Meth) acrylamide means acrylamide or methacrylamide.

  Moreover, as a photocationic polymerization type composition, as disclosed in JP 2011-08234 A, (α) a cationic polymerizable compound, (β) a photocationic polymerization initiator, and (γ) a wavelength longer than 380 nm. And an ultraviolet curable adhesive composition containing each component of a photosensitizer exhibiting maximum absorption in the light of (δ) and a naphthalene-based photosensitization aid. However, other ultraviolet curable adhesives may be used.

(1) Pre-processing process A pre-processing process is a process of performing an easily bonding process to the adhesive surface with the polarizer of an optical film. 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 adhesive 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 a doctor blade, a wire bar, a die coater, a comma coater, and a gravure coater can be used. Moreover, after casting an ultraviolet curable adhesive between a polarizer and an optical film, it is possible to use a method of applying pressure by a roller or the like and spreading it uniformly.

(2) Bonding process After apply | coating an ultraviolet curable adhesive by said method, it processes by a bonding process. In this bonding step, for example, when an ultraviolet curable adhesive is applied to the surface of the polarizer in the previous application step, an optical film is superimposed thereon. In the case of a system in which an ultraviolet curable adhesive is first applied to the surface of the optical film, a polarizer is superimposed thereon. In addition, when an ultraviolet curable adhesive is cast between the polarizer and the optical film, the polarizer and the optical film are superposed in that state. In this state, the pressure is usually sandwiched between pressure optical rollers from both sides with a pressure roller. Metal, rubber, or the like can be used as the material of the pressure roller. The pressure rollers arranged on both sides may be made of the same material or different materials.

(3) Curing step In the curing step, an uncured UV curable adhesive is irradiated with UV rays, and a cationic polymerizable compound (for example, an epoxy compound or an oxetane compound) or a radical polymerizable compound (for example, an acrylate compound, acrylamide). The ultraviolet curable adhesive layer containing the compound and the like is cured, and the laminated polarizer and the optical film are bonded via the ultraviolet curable adhesive. When bonding an optical film to the single side | surface of a polarizer, you may irradiate an active energy ray from either a polarizer side or an optical film side. In addition, when an optical film is pasted on both sides of a polarizer, both sides of the polarizer are irradiated with ultraviolet rays in a state where the optical films are superimposed on each other via an ultraviolet curable adhesive, and both sides of the ultraviolet curable adhesive are applied. It is advantageous to cure the two simultaneously.

Any appropriate conditions can be adopted as the ultraviolet irradiation conditions as long as the ultraviolet curable adhesive applied to the present invention can be cured. 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 performing the manufacturing process of a polarizing plate by a continuous line, although line speed is based on the hardening time of an adhesive agent, Preferably it is the range of 1-500 m / min, More preferably, it is the range of 5-300 m / min, More preferably, it is 10- The range is 100 m / min. When the line speed is 1 m / min or more, productivity can be ensured, or damage to the optical film can be suppressed, and a polarizing plate having excellent durability can be produced. If the line speed is 500 m / min or less, the ultraviolet curable adhesive is sufficiently cured, and an ultraviolet curable adhesive layer having a desired hardness and excellent adhesiveness can be formed.

[5.1.3]
It is preferable that the film arrange | positioned on the opposite side to the optical film of this invention of a polarizer is a film which functions as a protective film of a polarizer.

  As such a protective film, the optical film of the present invention may be used. , KC4KR, KC8UY, KC6UY, KC4UY, KC4UE, KC8UE, KC8UY-HA, KC2UA, KC4UA, KC6UAKC, 2UAH, KC4UAH, KC6UAH, Z TD60UL, FUJITAC TD40UL, FUJITAC R02, FUJI TAC R06, or more from FUJIFILM Corporation) 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, polyethersulfone, polysulfone, cycloolefin copolymer, polyimide ( Examples thereof include resin films such as Neoprim (registered trademark) manufactured by Mitsubishi Gas Chemical Co., Ltd., fluorene ring-modified polycarbonate, alicyclic modified polycarbonate, acryloyl compound, etc. (in parentheses indicate glass transition temperature Tg). 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.

  Although the thickness in particular of the said protective film B is not restrict | limited, It can be set as about 10-200 micrometers, Preferably it exists in the range of 10-100 micrometers, More preferably, it exists in the range of 10-70 micrometers.

[5.2] Liquid crystal display device By using the polarizing plate on which the optical film of the present invention is bonded to a liquid crystal display device, the liquid crystal display device of the present invention excellent in various visibility can be produced.

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

  In the liquid crystal display device, usually two polarizing plates, a polarizing plate on the viewing side and a polarizing plate on the backlight side, are used, but it is also preferable to use the polarizing plate of the present invention as both polarizing plates. It is also preferable to use as. In particular, the polarizing plate of the present invention is preferably used as a viewing-side polarizing plate that directly touches the external environment. In this case, when the optical film of the present invention is an optical compensation film, the polarizing plate may be disposed 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. In that case, both sides of the polarizer may be, for example, a commercially available cellulose ester film (for example, Konica Minoltack KC8UX, KC5UX, KC4UX, KC8UCR3, KC4SR, KC4BR, KC4CR, KC4DR, KC4FR, KC4KR, KC8UY, KC6UY, KC4UY, KC4UE, KC8UE, KC8UY-HA, KC2UA, KC4UA, KC6UA, KC4UAH, KC2UAH, KC4UAH, KC4UAH, KC4UAH, KC4UAH T60UZ, Fujitac T80UZ, Fujitac TD80UL, Fujitac TD60UL, Fujitac TD40UL, Fujitac R02, Fujitac R06, Fujifilm Corporation Polarizing plate stuck etc.) is preferably used.

  In addition, 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, retardation film, polyester film, acrylic film, polycarbonate film, or A polarizing plate on which a cycloolefin polymer film is bonded can also be preferably used.

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

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

  Regarding the outline of the organic EL element applicable to the organic electroluminescence display device used in the present invention, for example, JP2013-157634A, JP2013-168552A, JP2013-177361A, JP JP 2013-187221 A, JP 2013-191644 A, JP 2013-191804 A, JP 2013-225678 A, JP 2013-235994 A, JP 2013-243234 A, JP 2013-2013 A. JP 243236, JP 2013-242366, JP 2013-243371, JP 2013-245179, JP 2014-003249, JP 2014-003299, JP 2014-013910 JP, 2014-01 493 JP include a configuration described in JP-2014-017494 Patent Publication.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, although the display of "part" or "%" is used in an Example, unless otherwise indicated, "mass part" or "mass%" is represented.

Example 1
<Production of optical film>
(Synthesis of cycloolefin copolymer 1)
100 parts of a cycloolefin monomer (exemplary monomer No. 16) and a copolymerizable monomer (exemplary monomer No. 45) having a carboxy group at a molar ratio of 70:30, 3.6 parts of 1-hexene as a molecular weight regulator, 200 parts of toluene was charged into a nitrogen-substituted reaction vessel and heated to 80 ° C. To this, 0.17 part of a 1.5 mol / L toluene solution 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 heated at 80 ° C. for 3 hours. By stirring, a ring-opening polymerization reaction was performed to obtain a polymer solution. The polymerization conversion rate in this polymerization reaction was 98%.

4000 parts of the obtained polymer solution was put in an autoclave, 0.48 parts of RuHCl (CO) [P (C ₆ H ₅ ) ₃ ] ₃ was added to the polymer solution, the hydrogen gas pressure was 10 MPa, the reaction temperature. Hydrogenation reaction was performed by heating and stirring for 3 hours at 160 ° C.

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

  Moreover, the weight average molecular weight of the said cycloolefin type copolymer 1 was 130,000 as Mw of polystyrene conversion measured by the gel permeation chromatography (GPC).

  In the same manner, the ratio of the monomer to be added was changed, and copolymer 2 (molar ratio 50:50), copolymer 3 (molar ratio 10:90), copolymer 4 (molar ratio 1:99), copolymer Polymer 5 (molar ratio 20:80) was produced.

  As a comparative example, Arton G7810 manufactured by JSR was prepared.

  The weight average molecular weights of the copolymers 2 to 5 and Arton G7810 were 130,000 as Mw in terms of polystyrene measured by gel permeation chromatography (GPC).

<Preparation of optical film 101>
(Preparation of fine particle additive solution)
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 with a dissolver for 50 minutes, dispersed with Manton Gorin Went.

  Further, the particles were dispersed by an attritor so that the secondary particles had a predetermined particle size. This was filtered through Finemet NF manufactured by Nippon Seisen Co., Ltd. to prepare a fine particle additive solution.

  Next, 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 at a flow rate of 20 kg / min. Three minutes after the start of the addition of the solvent, the cycloolefin copolymer 1 was added to the pressurized dissolution tank with stirring at a flow rate of 200 kg / min. Next, 5 minutes after the start of solvent addition, the fine particle additive solution 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 was designated as Azumi Filter Paper No. The main dope 1 was prepared by using 244 (filtration accuracy 0.005 mm) and filtering 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 solution 15 parts by mass Next, using an endless belt casting apparatus, the dope is a stainless steel belt support at a temperature of 33 ° C. and a width of 1.5 m. Cast evenly on top. The temperature of the stainless steel belt was controlled at 30 ° C.

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

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

<Preparation of optical films 102-106>
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), and the copolymer 4 (molar ratio 1:99). ), Copolymer 5 (molar ratio 20:80) and Arton G7810 manufactured by JSR Corporation were used in the same manner to prepare optical films 102 to 106, respectively.

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

<Preparation of cycloolefin copolymer 6>
Exemplified monomer no. 45, 100 g of 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, to which 10.8 mol / L NaOH aqueous solution was added, and heated to 80 ° C. The mixture was stirred vigorously for 12 hours (hydrolysis), allowed to cool, and then added with hydrochloric acid (acid treatment) to neutralize. 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 resulting organic phase is dried by heating under reduced pressure, and a cycloolefin having a carboxy group A polymer B having a monomer-derived structure was obtained at a yield of 95%.

  The weight average molecular weight of the copolymer 6 was 130,000 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 deuterated chloroform solvent, and H-NMR measurement was performed.

  Compared to polymer A, in polymer B, the peak derived from the methyl group hydrogen of the ester moiety observed near 3.6 ppm is higher than the peak derived from alkyl hydrogen other than the above appearing from 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 the cycloolefin-based monomer having a carboxy group was calculated from the ratio, which was 25%.

≪Evaluation≫
[1] Measurement of pH value of optical film The pH value of the optical film is obtained by bubbling “ion-exchanged water” specified in JIS K 0557 with nitrogen gas for 15 minutes or more by the method specified in JIS K 8001: 2009. Decarbonated water was prepared under a nitrogen gas atmosphere. The entire optical film cut into 5 cm square was immersed in 15 mL of prepared decarbonated water at 23 ° C. for 15 minutes under a nitrogen atmosphere, and a pH electrode was placed in the liquid and measured. The pH electrode used was HM-30R manufactured by Toa DK Corporation.

[2] Polarizer adhesion A polarizing plate was prepared using the optical films 101 to 107 prepared 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.

  Subsequently, the produced polarizer is sandwiched between the produced optical films 101 to 107 and Konica Minoltak KC4UA (manufactured by Konica Minolta Co., Ltd.) as a polarizer protective film, and the following ultraviolet curable adhesive liquid is used. And bonded to each other to produce a polarizing plate.

  In that case, it bonded so that the absorption axis of a polarizer and the slow axis of the optical film of this invention might orthogonally cross.

[Preparation of UV curable adhesive solution 1]
After mixing the following components, defoaming was performed to prepare an ultraviolet curable adhesive liquid 1. Triarylsulfonium hexafluorophosphate was blended as a 50% propylene carbonate solution, and the solid content of triarylsulfonium hexafluorophosphate was 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 In addition, the polarizing plate was prepared on the surface of the film with a corona output strength of 2. Corona discharge treatment was performed at 0 kW and a line speed of 18 m / min, and the prepared UV curable adhesive liquid 1 was applied to the corona discharge treatment surface with a bar coater so that the film thickness after curing was about 3 μm. Thus, an ultraviolet curable adhesive layer was formed.

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

  100 grid-shaped cuts were made on the optical film surface of the produced polarizing plate so as to penetrate the film using a cutter guide having a gap interval 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 (Cello Tape (registered trademark) CT-18 manufactured by Nichiban Co., Ltd.) was applied to the cut surface of the grid, and a 2.0 kg roller was reciprocated 20 times from above to remove the air remaining at the interface. Pressed with an eraser to ensure complete contact. And it peeled off rapidly, keeping the peeling angle at 180 degreeC. After peeling off, the operation of applying a new tape and peeling off was repeated 10 times in the same manner as described above. The peeling rate of the optical film at that time was evaluated according to the following criteria.

A: Peeling area is less than 3% B: Peeling area is 3% or more and less than 5% X: Peeling area is 5% or more [3] Optical unevenness Liquid crystal display device with curved display section (55HU9000, manufactured by Samsunung Corporation, curvature radius 4200 mm The polarizing plate was peeled off from the liquid crystal panel and the prepared polarizing plate was attached so that the absorption axis of the polarizing plate and the position of the optical axis of the retardation film were the same as the original.

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

○: No display unevenness occurred. ×: Display unevenness occurred. Table 1 shows the configuration and evaluation results of the optical film.

  From Table 1, the optical films 101 to 104 and 107 of the present invention are excellent in polarizer adhesion and excellent in suppressing the occurrence of display unevenness even when the display unit is mounted on a curved liquid crystal display device. I understood.

  In the optical film 105 of the comparative example, since the pH value of the film is on the acidic side, deterioration due to pigment decomposition of the polarizer was observed, and display unevenness was inferior.

  The optical film 106 of the comparative example was insufficient in the plastic effect, causing poor adhesion and display unevenness.

Example 2
<Preparation of Optical Film 201-207 for Circular Polarizing Plate>
In preparation of the optical films 101-107 of Example 1, instead of the extending | stretching process to the width direction, using the extending | stretching method and extending | stretching apparatus to the diagonal direction of Unexamined-Japanese-Patent No. 2005-321543, with respect to a conveyance direction. The optical films 201 to 207 for circularly polarizing plates that are stretched in an oblique 45 ° direction and the slow axis is in an oblique 45 ° direction with respect to the longitudinal direction are produced so as to correspond to the optical films 101 to 107, respectively. did.

  When the optical film was measured at an optical wavelength of 550 nm under the environment of 23 ° C. and 55% RH by the above-described method of measuring the retardation values Ro and Rt, Ro = 140 nm, Rt = 90 nm, and 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 Tack KC4UA (manufactured by Konica Minolta Co., Ltd.)), and the ultraviolet curable adhesive liquid 1 is interposed therebetween. Then, the polarizer was bonded so that the absorption axis of the polarizer and the slow axis of the optical film were 45 ° to form a circularly polarizing plate.

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

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

  Moreover, the state when the display screen was viewed through the polarized sunglasses was better in the state using the circularly polarizing plate of the present invention than in the state where the original PET film was used. This is because the original PET film has been depolarized due to the ultrahigh retardation, whereas the circularly polarizing plate of the present invention is optically compensated as a λ / 4 retardation film. It has been found that the optical film of the present invention is suitable for curved display applications.

DESCRIPTION OF SYMBOLS 1 Melting pot 3, 6, 12, 15 Filter 4, 13 Stock pot 2, 5, 11, 14 Liquid feed pump 8, 16 Conduit 10 Additive charging tank 20 Merge pipe 21 Mixer 30 Pressure die 31 Metal support 32 Web 33 Peeling position 34 1st drying device 35 Stretching device 36 2nd drying device 37 Conveying roller 38 Winding device 41 Preparation kettle 42 Stock kettle 43 Pump 44 Filter

Claims (7)

  An optical film containing at least a cycloolefin copolymer having a structure derived from a cycloolefin monomer having a carboxy group, wherein the optical film is immersed in decarbonated water at a liquid temperature of 23 ° C. in a nitrogen atmosphere for 15 minutes. An optical film having a pH value of 5.7 to 7.3 when the measured liquid is measured. The optical film according to claim 1, wherein the cycloolefin monomer has a structure represented by the following general formula (a).

(In the formula, B ^{1 to} B ³ are each independently a hydrogen atom; a halogen atom; a substituted or unsubstituted carbon atom having 1 to 30 carbon atoms which may have a linking group containing oxygen, nitrogen, sulfur or silicon. Represents a hydrogen group; or represents a polar group, B ⁴ represents COOH, and p represents a natural number of 0 to 2.) ^3. The optical film according to claim 2, wherein in the general formula (a), p = 1, B ¹ and B ² = H, B ³ = Me, and B ⁴ = COOH.   The copolymerization ratio of the cycloolefin 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 copolymer. Item 4. The optical film according to Item 2 or Item 3.   A polarizing plate, wherein the optical film according to any one of claims 1 to 4 is disposed on at least one surface of a polarizer.   A display device comprising the polarizing plate according to claim 5.   The display device according to claim 6, wherein a radius of curvature of a display unit of the display device is in a range of 1 to 5000 mm.

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