JPWO2008108199A1 - Retardation film, method for producing the same, and polarizing plate - Google Patents

Abstract

It is an object of the present invention to provide a retardation film having an NZ coefficient close to 1 and less warping after bonding with a polarizing film, a method for producing the same, and a polarizing plate using the film. The retardation film of the present invention is made of a cyclic olefin polymer and satisfies the following formulas (1) to (5). (1) 70 nm ≦ Re ≦ 300 nm, (2) 1.1 ≦ NZ ≦ 1.7, (3) α (MD) ≦ 90 ppm / ° C., (4) α (TD) ≦ 90 ppm / ° C., (5) | α (MD) −α (TD) | ≦ 30 ppm / ° C.

Description

  The present invention relates to a retardation film made of a cyclic olefin polymer, a method for producing the same, and a polarizing plate using the retardation film.

  Cyclic olefin resins have a high glass transition temperature due to the rigidity of the main chain structure, a bulky group in the main chain structure, so that they are amorphous, have high light transmittance, and have an anisotropic refractive index. It has features such as low birefringence due to its low properties, and has attracted attention as a transparent thermoplastic resin excellent in heat resistance, transparency and optical properties.

  In recent years, application of the above-mentioned cyclic olefin-based resins to fields such as optical materials such as optical disks, optical lenses, and optical fibers, and sealing materials such as optical semiconductor sealing has been studied. In addition, an attempt has been made to improve the problems of conventional optical films as shown below by applying to optical films.

  Polycarbonate, polyester, or triacetyl cellulose films that have been used for optical films have a large photoelastic coefficient, so that a phase difference may appear or change due to minute stress changes, and heat resistance and water absorption deformation Because of such problems as inferior properties, films made of cyclic olefin resins have been proposed as various optical films. For example, Patent Documents 1 and 2 describe retardation plates made of a cyclic olefin resin film. Patent Documents 3 to 5 describe the use of a cyclic olefin resin film as a protective film for a polarizing plate.

  These publications describe that the film of the cyclic olefin resin has a water absorption of 0.05% or less and is excellent in this low water absorption. However, when such a low water-absorbing cyclic olefin-based resin film is used as, for example, a retardation plate or a substrate for a liquid crystal display element, adhesion of a hard coat, an antireflection film or a transparent conductive layer, or a polarizing plate There may be problems with adhesion to glass and glass. When used as a protective film for a polarizing plate, in addition to the above problem, the water permeability of the water-based adhesive usually used for bonding to the polarizing film is difficult to dry because the moisture permeability is low as well as the water absorption rate. Problems also arise.

  On the other hand, various kinds of cyclic olefin resins are known, and the water absorption rate of all cyclic olefin resins is not necessarily 0.05% or less. In order to make the water absorption rate 0.05% or less, the cyclic olefin-based resin needs to have a polyolefin structure consisting of only carbon atoms and hydrogen atoms or a structure containing a part of halogen.

  Then, in order to solve the problem originating in the said low water absorption, the optical film containing the cyclic olefin resin which introduce | transduced the polar group in the molecule | numerator is described in patent documents 6-7. These optical films are excellent in optical properties such as high transparency, low retardation of transmitted light, and uniform and stable retardation when stretched and oriented, heat resistance, adhesion to other materials, adhesion, etc. It has the advantage of being good and having little water absorption deformation, and is used in many liquid crystal display elements.

However, with the recent increase in the size of liquid crystal display elements, improvement in brightness contrast ratio, and improvement in viewing angle recognition, etc., the optical film used does not disturb the visibility of the image. Further uniformity and stability are desired. For this reason, the appearance of a retardation film and a polarizing plate excellent in bonding with a polarizing film has been demanded. For example, Patent Document 8 discloses a polarizing plate with reduced warpage after bonding a protective film, which is a problem in manufacturing and mounting on a liquid crystal display element. These combinations are limited, and further improvements have been demanded.
JP-A-5-2108 Japanese Patent Laid-Open No. 5-64865 Japanese Patent Laid-Open No. 5-212828 JP-A-6-511117 JP-A-7-77608 JP 7-287122 A JP 7-287123 A JP-A-2005-215700

  An object of the present invention is to provide a retardation film having an NZ coefficient close to 1 and less warping after bonding with a polarizing film, a method for producing the same, and a polarizing plate using the film.

The retardation film of the present invention is composed of a cyclic olefin polymer and satisfies the following formulas (1) to (5).
(1) 70 nm ≦ Re ≦ 300 nm
(2) 1.1 ≦ NZ ≦ 1.7
(In the formulas (1) and (2), Re is an in-plane retardation of the film at a wavelength of 589 nm, and is represented by Re = (nx−ny) × d, and NZ is NZ = (nx−nz) / ( nx-ny) where nx is the maximum refractive index in the film plane, ny is the refractive index in the direction perpendicular to nx in the film plane, and nz is orthogonal to nx and ny. The refractive index in the film thickness direction, d represents the thickness (nm) of the film.)
(3) α (MD) ≦ 90 ppm / ° C.
(4) α (TD) ≦ 90 ppm / ° C.
(5) | α (MD) −α (TD) | ≦ 30 ppm / ° C.
(In the formulas (3) to (5), α (MD) represents an average linear expansion coefficient in the film longitudinal direction, and α (TD) represents an average linear expansion coefficient in the film width direction. However, the average linear expansion coefficient Are all values at −40 ° C. to 85 ° C.)
In the retardation film of the present invention, the cyclic olefin polymer preferably has a structural unit represented by the following formula (I).

［式（Ｉ）中、ｍは１以上の整数であり、ｐは０または１以上の整数であり、Ｄは−ＣＨ＝ＣＨ−または−ＣＨ_２ＣＨ_２−で表される基であり、Ｒ^１〜Ｒ^４はそれぞれ独立に水素原子；ハロゲン原子；酸素原子、硫黄原子、窒素原子もしくはケイ素原子を含む連結基；置換もしくは非置換の炭素原子数１〜３０の炭化水素基；極性基よりなる群から選ばれる原子もしくは基を表し、Ｒ^１およびＲ^２は一体化して２価の炭化水素基を形成してもよく、Ｒ^３およびＲ^４は一体化して２価の炭化水素基を形成してもよい。Ｒ^１およびＲ^２は互いに結合して炭素環または複素環を形成してもよく、Ｒ^３およびＲ^４は互いに結合して炭素環または複素環を形成してもよく、該炭素環または複素環は単環でも多環でもよい。］
本発明の位相差フィルムは、フィルム厚みが２０〜１００μｍであり、フィルムの最大厚みと最小厚みとの差が３μｍ以内であることが好ましい。

[In the formula (I), m is an integer of 1 or more, p is 0 or an integer of 1 or more, D is a group represented by —CH═CH— or —CH ₂ CH ₂ —, R ^{1 to} R ⁴ are each independently a hydrogen atom; a halogen atom; a linking group containing an oxygen atom, a sulfur atom, a nitrogen atom or a silicon atom; a substituted or unsubstituted hydrocarbon group having 1 to 30 carbon atoms; a polar group Represents an atom or group selected from the group, R ¹ and R ² may be combined to form a divalent hydrocarbon group, and R ³ and R ⁴ may be combined to form a divalent hydrocarbon group. May be. R ¹ and R ² may be bonded to each other to form a carbocyclic or heterocyclic ring, and R ³ and R ⁴ may be bonded to each other to form a carbocyclic or heterocyclic ring. May be monocyclic or polycyclic. ]
The retardation film of the present invention has a film thickness of 20 to 100 μm, and the difference between the maximum thickness and the minimum thickness of the film is preferably 3 μm or less.

  The method for producing a retardation film of the present invention is a cyclic olefin polymer film (raw film) having a film thickness of 100 to 250 μm and a difference between the maximum thickness and the minimum thickness of the film of 3 μm or less. The retardation film is obtained by transversely uniaxially stretching so as to be 2.5 to 5.5 times.

  The polarizing plate of the present invention is characterized in that the retardation film is laminated on at least one side of a polarizing film.

  When the retardation film made of the cyclic olefin polymer of the present invention is stretched transversely at a draw ratio of 2.5 to 5.5 times, a film having a NZ coefficient close to 1 and less warping after bonding with a polarizing film is obtained. It is suitably used for a vertical alignment type liquid crystal display element.

Hereinafter, the present invention will be specifically described.
<Phase difference film>
The retardation film of the present invention is made of a cyclic olefin polymer and satisfies the following formulas (1) to (5).
(1) 70 nm ≦ Re ≦ 300 nm
(2) 1.1 ≦ NZ ≦ 1.7
(In the formulas (1) and (2), Re is the in-plane retardation of the film at a wavelength of 589 nm, and is represented by Re = (nx−ny) × d, and NZ is NZ = (nx−nz). / (Nx−ny) where nx is the maximum refractive index in the film plane, ny is the refractive index in the direction perpendicular to nx in the film plane, and nz is relative to nx and ny. The refractive index in the film thickness direction orthogonal to each other, d represents the thickness (nm) of the film.)
(3) α (MD) ≦ 90 ppm / ° C.
(4) α (TD) ≦ 90 ppm / ° C.
(5) | α (MD) −α (TD) | ≦ 30 ppm / ° C.
(In the formulas (3) to (5), α (MD) represents an average linear expansion coefficient in the film longitudinal direction, and α (TD) represents an average linear expansion coefficient in the film width direction. However, the average linear expansion coefficient Are all values at −40 ° C. to 85 ° C.)
(1) and (2) are optical characteristics that affect the viewing angle compensation performance of the liquid crystal element, and preferred values differ depending on the type and display format of the liquid crystal used in the liquid crystal element. The value of Re is preferably 75 nm to 200 nm, more preferably 75 nm to 150 nm in order to prevent light leakage when viewed from an oblique direction during black display of the liquid crystal element and to obtain good viewing angle compensation. preferable. The NZ value of (2) is preferably closer to 1 for viewing angle compensation of the vertical alignment type liquid crystal element, preferably 1.1 to 1.5, more preferably 1.1 to 1.4.

When performing viewing angle compensation of a vertical alignment type liquid crystal device using the polarizing plate of the present invention, it is preferable to provide a retardation layer of Re ≦ 60 nm and NZ ≧ 3 on the paired polarizing plate side. This is preferable in view angle compensation. (Definition formulas for the in-plane retardation Re and NZ of the retardation layer are as described above, nx is the maximum refractive index in the retardation layer surface, and ny is the refraction in the direction perpendicular to nx in the retardation layer surface. The refractive index in the thickness direction of the retardation layer orthogonal to nx and ny, and d (nm) represents the thickness of the retardation layer.
As for (3) and (4), it means that the smaller the α value, the smaller the dimensional change due to temperature change. However, except for heat-resistant resins such as polyimide, polyethersulfone, polyphenylene sulfide, etc., thermoplastic resins generally have a larger coefficient of linear expansion than glass or metal, and the resin alone cannot have a coefficient of linear expansion approaching zero. Absent. Moreover, there is a possibility that the balance of dimensional changes with other resins such as polyvinyl alcohol constituting the polarizing plate may be lost, and the lower the linear expansion coefficient, the better. However, a dimensional change of a certain level or more is not preferable because it causes warping and undulation by heating during drying of the polarizing plate. Therefore, both α (MD) and α (TD) are more realistically 30 ppm / ° C. to 90 ppm / ° C.

  (5) represents the anisotropy of dimensional change due to temperature change. The larger the difference between α (MD) and α (TD), the greater the difference in dimensional change depending on the direction of the film, and warpage tends to occur. Preferably, | α (MD) −α (TD) | ≦ 25 ppm / ° C., more preferably | α (MD) −α (TD) | ≦ 20 ppm / ° C.

<Cyclic olefin polymer>
The cyclic olefin polymer used in the present invention is not particularly limited, and the ring-opening (co) polymer of a cyclic olefin monomer as represented by the following formula (I ′) and formula (II ′): Hydrides of the ring-opening (co) polymers, addition (co) polymers, addition copolymers of cyclic olefin monomers and α-olefins, and the like. Among these, a hydride of a ring-opening (co) polymer is preferable, and a polymer having a structural unit represented by the following general formula (I) is particularly preferable. The polymer may be a homopolymer having a structural unit represented by the following general formula (I), or a copolymer having a structural unit represented by the following general formula (II) together with the formula (I). It may be a coalescence.

［式（Ｉ）中、ｍは１以上の整数であり、ｐは０または１以上の整数であり、Ｄは−ＣＨ＝ＣＨ−または−ＣＨ_２ＣＨ_２−で表される基であり、Ｒ^１〜Ｒ^４はそれぞれ独立に水素原子；ハロゲン原子；酸素原子、硫黄原子、窒素原子もしくはケイ素原子を含む連結基；置換もしくは非置換の炭素原子数１〜３０の炭化水素基；極性基よりなる群から選ばれる原子もしくは基を表し、Ｒ^１およびＲ^２は一体化して２価の炭化水素基を形成してもよく、Ｒ^３およびＲ^４は一体化して２価の炭化水素基を形成してもよい。Ｒ^１およびＲ^２は互いに結合して炭素環または複素環を形成してもよく、Ｒ^３およびＲ^４は互いに結合して炭素環または複素環を形成してもよく、該炭素環または複素環は単環でも多環でもよい。］

[In the formula (I), m is an integer of 1 or more, p is 0 or an integer of 1 or more, D is a group represented by —CH═CH— or —CH ₂ CH ₂ —, R ^{1 to} R ⁴ are each independently a hydrogen atom; a halogen atom; a linking group containing an oxygen atom, a sulfur atom, a nitrogen atom or a silicon atom; a substituted or unsubstituted hydrocarbon group having 1 to 30 carbon atoms; a polar group Represents an atom or group selected from the group, R ¹ and R ² may be combined to form a divalent hydrocarbon group, and R ³ and R ⁴ may be combined to form a divalent hydrocarbon group. May be. R ¹ and R ² may be bonded to each other to form a carbocyclic or heterocyclic ring, and R ³ and R ⁴ may be bonded to each other to form a carbocyclic or heterocyclic ring. May be monocyclic or polycyclic. ]

［式（ＩＩ）中、Ｅは、独立に−ＣＨ＝ＣＨ−または−ＣＨ_２ＣＨ_２−で表される基であり、Ｒ^５〜Ｒ^８は、各々独立に水素原子；ハロゲン原子；酸素原子、硫黄原子、窒素原子もしくはケイ素原子を含む連結基；置換もしくは非置換の炭素原子数１〜３０の炭化水素基；極性基を表し、Ｒ^５とＲ^６は一体化して２価の炭化水素基を形成してもよく、Ｒ^７とＲ^８は一体化して２価の炭化水素基を形成してもよい。Ｒ^５またはＲ^６と、Ｒ^７またはＲ^８とは相互に結合して炭素環または複素環を形成してもよく、該炭素環または複素環は、単環構造でも多環構造でもよい。］
環状オレフィン系重合体のガラス転移温度をフィルム加工に適した領域にし、同時に複屈折制御性を確保するため、上記一般式（Ｉ）におけるｍは好ましくは１〜５、より好ましくは１〜３、さらに好ましくは１〜２であり、ｐは好ましくは０〜４、より好ましくは０〜２、さらに好ましくは０〜１である。また、Ｒ^１〜Ｒ^４の炭素原子数は好ましくは１〜２５、より好ましくは１〜２０、さらに好ましくは１〜１０である。さらに、上記一般式（ＩＩ）におけるＲ^５〜Ｒ^８の炭素原子数は好ましくは１〜２５、より好ましくは１〜２０、さらに好ましくは１〜１０である。

[In Formula (II), E is a group independently represented by —CH═CH— or —CH ₂ CH ₂ —, and R ^{5 to} R ⁸ each independently represents a hydrogen atom; a halogen atom; an oxygen atom. , A linking group containing a sulfur atom, a nitrogen atom or a silicon atom; a substituted or unsubstituted hydrocarbon group having 1 to 30 carbon atoms; a polar group, wherein R ⁵ and R ⁶ are a divalent hydrocarbon group R ⁷ and R ⁸ may be integrated to form a divalent hydrocarbon group. R ⁵ or R ⁶ and R ⁷ or R ⁸ may be bonded to each other to form a carbocyclic or heterocyclic ring, and the carbocyclic or heterocyclic ring may be a monocyclic structure or a polycyclic structure. ]
In order to make the glass transition temperature of the cyclic olefin polymer suitable for film processing and at the same time to ensure birefringence controllability, m in the general formula (I) is preferably 1 to 5, more preferably 1 to 3, More preferably, it is 1-2, p becomes like this. Preferably it is 0-4, More preferably, it is 0-2, More preferably, it is 0-1. The number of carbon atoms of R ^{1 to} R ⁴ is preferably 1 to 25, more preferably 1 to 20, and still more preferably 1 to 10. Furthermore, the number of carbon atoms of R ^{5 to} R ⁸ in the general formula (II) is preferably 1 to 25, more preferably 1 to 20, and still more preferably 1 to 10.

Production Method The cyclic olefin polymer according to the present invention has a structural unit represented by the above formula (I) and, if necessary, a structural unit represented by the above formula (II).

  The structural unit represented by the above formula (I) is derived from a cyclic olefin monomer represented by the following formula (I ′) by ring-opening (co) polymerization.

（式（Ｉ’）中、ｍ、ｐおよびＲ^１〜Ｒ^４は、前記式（Ｉ）と同様である。）
式（Ｉ）または式（Ｉ’）において、極性基としては、たとえば、水酸基、炭素原子数１〜１０のアルコキシ基、カルボニルオキシ基、アルコキシカルボニル基、アリーロキシカルボニル基、シアノ基、アミド基、イミド基、トリオルガノシロキシ基、トリオルガノシリル基、アミノ基、アシル基、アルコキシシリル基、スルホニル基、およびカルボキシル基などが挙げられる。さらに具体的には、上記アルコキシ基としては、たとえばメトキシ基、エトキシ基などが挙げられ；カルボニルオキシ基としては、たとえばアセトキシ基、プロピオニルオキシ基などのアルキルカルボニルオキシ基、およびベンゾイルオキシ基などのアリールカルボニルオキシ基が挙げられ；アルコキシカルボニル基としては、たとえばメトキシカルボニル基、エトキシカルボニル基などが挙げられ；アリーロキシカルボニル基としては、たとえばフェノキシカルボニル基、ナフチルオキシカルボニル基、フルオレニルオキシカルボニル基、ビフェニリルオキシカルボニル基などが挙げられ；トリオルガノシロキシ基としては、たとえばトリメチルシロキシ基、トリエチルシロキシ基などが挙げられ；トリオルガノシリル基としてはトリメチルシリル基、トリエチルシリル基などが挙げられ；アミノ基としては第１級アミノ基が挙げられ、アルコキシシリル基としては、たとえばトリメトキシシリル基、トリエトキシシリル基などが挙げられる。

(In formula (I ′), m, p and R ^{1 to} R ⁴ are the same as those in formula (I).)
In the formula (I) or the formula (I ′), examples of the polar group include a hydroxyl group, an alkoxy group having 1 to 10 carbon atoms, a carbonyloxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, a cyano group, an amide group, Examples thereof include an imide group, a triorganosiloxy group, a triorganosilyl group, an amino group, an acyl group, an alkoxysilyl group, a sulfonyl group, and a carboxyl group. More specifically, examples of the alkoxy group include a methoxy group and an ethoxy group; examples of the carbonyloxy group include an alkylcarbonyloxy group such as an acetoxy group and a propionyloxy group, and an aryl such as a benzoyloxy group. Examples of the alkoxycarbonyl group include a methoxycarbonyl group and an ethoxycarbonyl group; examples of the aryloxycarbonyl group include a phenoxycarbonyl group, a naphthyloxycarbonyl group, a fluorenyloxycarbonyl group, Examples of the triorganosiloxy group include trimethylsiloxy group and triethylsiloxy group; examples of the triorganosilyl group include trimethyl Silyl groups, such as triethylsilyl group and the like; examples of the amino group include primary amino group, the alkoxysilyl group, for example a trimethoxysilyl group, a triethoxysilyl group.

Examples of the halogen atom include a fluorine atom, a chlorine atom, and a bromine atom.
Examples of the hydrocarbon group having 1 to 10 carbon atoms include alkyl groups such as methyl group, ethyl group, and propyl group; cycloalkyl groups such as cyclopentyl group and cyclohexyl group; alkenyl groups such as vinyl group, allyl group, and propenyl group. Groups and the like.

In addition, the substituted or unsubstituted hydrocarbon group may be directly bonded to the ring structure, or may be bonded via a linking group. As the linking group, for example, a divalent hydrocarbon group having 1 to 10 carbon atoms (for example, an alkylene group represented by — (CH ₂ ) _m — (wherein m is an integer of 1 to 10)); oxygen , A linking group containing nitrogen, sulfur or silicon (for example, a carbonyl group (—CO—), an oxycarbonyl group (—O (CO) —), a sulfone group (—SO ₂ —), an ether bond (—O—), Thioether bond (—S—), imino group (—NH—), amide bond (—NHCO—, —CONH—), siloxane bond (—OSi (R ₂ ) — (wherein R is an alkyl such as methyl or ethyl) Group)) and the like, and a linking group containing a plurality of these may be used.

Specific examples of the cyclic olefin monomer (I ′) include the following compounds.
Tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
Pentacyclo [6.5.1.1 ^3,6 . 0 ^2,7 . 0 ^9,13 ] -4-pentadecene,
8-methyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-ethyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-methoxycarbonyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-ethoxycarbonyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-n-propoxycarbonyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-Isopropoxycarbonyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-n-butoxycarbonyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-methyl-8-methoxycarbonyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-methyl-8-ethoxycarbonyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-methyl-8-n-propoxycarbonyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-methyl-8-isopropoxycarbonyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-methyl-8-n-butoxycarbonyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-cyanotetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-cyano-8-methyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-ethylidenetetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-phenyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-fluorotetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-fluoromethyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-difluoromethyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-trifluoromethyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-pentafluoroethyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8,8-difluorotetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8,9-difluorotetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8,8-bis (trifluoromethyl) tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8,9-bis (trifluoromethyl) tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-methyl-8-trifluoromethyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8,8,9-trifluorotetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8,8,9-tris (trifluoromethyl) tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8,8,9,9-tetrafluorotetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8,8,9,9-tetrakis (trifluoromethyl) tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8,8-difluoro-9,9-bis (trifluoromethyl) tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8,9-difluoro-8,9-bis (trifluoromethyl) tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8,8,9-trifluoro-9-trifluoromethyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8,8,9-trifluoro-9-trifluoromethoxytetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8,8,9-trifluoro-9-pentafluoropropoxytetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-fluoro-8-pentafluoroethyl-9,9-bis (trifluoromethyl) tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8,9-difluoro-8-heptafluoroisopropyl-9-trifluoromethyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-chloro-8,9,9-trifluorotetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8,9-dichloro-8,9-bis (trifluoromethyl) tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8- (2,2,2-trifluoroethoxycarbonyl) tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-methyl-8- (2,2,2-trifluoroethoxycarbonyl) tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene.

These can be used alone or in combination of two or more.
In the present invention, the structural unit represented by the formula (I) preferably has a polar group, and the polar group is preferably a group represented by the following formula (III). That is, in the structural unit represented by the formula (I) or the cyclic olefin monomer represented by the formula (I ′), at least one of R ^{1 to} R ⁴ is represented by the following formula (III). It is preferably a group.

_{- (CH 2) n COOR '} ... (III)
(In formula (III), n is 0 or an integer of 1 to 5, and R ′ is a hydrocarbon group having 1 to 15 carbon atoms.)
In the above formula (III), the smaller the value of n and the smaller the R ′ is, the higher the glass transition temperature of the copolymer obtained and the better the heat resistance. That is, n is usually 0 or an integer of 1 to 5, preferably 0 or 1, and particularly preferably 0. R ′ is usually a hydrocarbon group having 1 to 15 carbon atoms, preferably an alkyl group having 1 to 3 carbon atoms, more preferably an alkyl group having 1 to 2 carbon atoms.

  Furthermore, in the above formula (I) or (I ′), when an alkyl group is further bonded to the carbon atom to which the polar group represented by the general formula (III) is bonded, the heat resistance of the resulting copolymer is reduced. This is preferable for achieving a balance between the property and water absorption (wet) property. Moreover, it is preferable that the carbon atom number of an alkyl group is 1-5, More preferably, it is 1-2, Most preferably, it is 1.

  The structural unit represented by the formula (II) is derived from a cyclic olefin monomer (II) represented by the following formula (II ′) by ring-opening copolymerization.

（式（ＩＩ’）中、Ｒ^５〜Ｒ^８は前記式（ＩＩ）と同様である。）
このような環状オレフィン系単量体としては、具体的には次のような化合物が挙げられる。

(In formula (II ′), R ^{5 to} R ⁸ are the same as those in formula (II).)
Specific examples of such cyclic olefin monomers include the following compounds.

Tricyclo [4.3.0.1 ^2,5 ] deca-3,7-diene,
Bicyclo [2.2.1] hept-2-ene,
Bicyclo [2.2.1] hepta-2,5-diene,
5-methylbicyclo [2.2.1] hept-2-ene,
5-ethylbicyclo [2.2.1] hept-2-ene,
5-propylbicyclo [2.2.1] hept-2-ene,
5-butylbicyclo [2.2.1] hept-2-ene,
5-pentylbicyclo [2.2.1] hept-2-ene,
5-hexylbicyclo [2.2.1] hept-2-ene,
5-heptylbicyclo [2.2.1] hept-2-ene,
5-octylbicyclo [2.2.1] hept-2-ene,
5-nonylbicyclo [2.2.1] hept-2-ene,
5-decylbicyclo [2.2.1] hept-2-ene,
5-undecylbicyclo [2.2.1] hept-2-ene,
5-dodecylbicyclo [2.2.1] hept-2-ene,
5-tridecylbicyclo [2.2.1] hept-2-ene,
5-tetradecylbicyclo [2.2.1] hept-2-ene,
5-pentadecylbicyclo [2.2.1] hept-2-ene,
5-hexadecylbicyclo [2.2.1] hept-2-ene,
5-heptadecylbicyclo [2.2.1] hept-2-ene,
5-octadecylbicyclo [2.2.1] hept-2-ene,
5-nonadecylbicyclo [2.2.1] hept-2-ene,
5-icosylbicyclo [2.2.1] hept-2-ene,
5-phenylbicyclo [2.2.1] hept-2-ene,
5-cyanobicyclo [2.2.1] hept-2-ene,
5-methoxycarbonylbicyclo [2.2.1] hept-2-ene,
5-ethoxycarbonylbicyclo [2.2.1] hept-2-ene,
5-methoxycarbonyl-5-methylbicyclo [2.2.1] hept-2-ene,
5-ethoxycarbonyl-5-methylbicyclo [2.2.1] hept-2-ene,
5-cyano-5-methylbicyclo [2.2.1] hept-2-ene 5-ethylidenebicyclo [2.2.1] hept-2-enespiro [fluorene-9,8'-tricyclo [4.3. 0.1 ^2.5] [3] decene].

These can be used alone or in combination of two or more. Of these, bicyclo [2.2.1] hept-2-ene and tricyclo [4.3.0.1 ^2,5 ] deca-3,7-diene are preferably used in the present invention.

The cyclic olefin polymer of the present invention can be produced by ring-opening copolymerization of one or more cyclic olefin monomers (I ′) and cyclic olefin monomers (II ′). . In order to make the cyclic olefin polymer of the present invention have heat resistance and appropriate water absorption, 8-methyl-8-methoxycarbonyltetracyclo [4.4.0.1 ^2,5 . It is particularly preferable that the copolymer be composed of ^{17, 10} ] -3-dodecene and bicyclo [2.2.1] hept-2-ene.

  In the present invention, the copolymerization ratio of the cyclic olefin monomer (compound represented by formula (I ′)) and the cyclic olefin monomer (compound represented by formula (II ′)) is the sum of these. Is usually 0 to 40 parts by weight, preferably 3 to 30 parts by weight, based on 100 parts by weight of the cyclic olefin monomer (II ′). If the copolymerization ratio of the cyclic olefin monomer (II ′) exceeds 30 parts by weight, the glass transition temperature may be lowered, and the heat resistance stability of various film properties such as retardation and dimensions may be lowered. On the other hand, if it is less than 3 parts by weight, the slidability, toughness, stretching workability and retardation development property of the resulting molded article, film or sheet may be lowered.

  In the present invention, in addition to these cyclic olefin monomers (I ′) and (II ′), other cyclic olefin monomers or other copolymerizable monomers may be used as long as the object of the present invention is not impaired. A small amount of a monomer can be used as a copolymer raw material monomer, and the cyclic olefin polymer of the present invention can contain structural units other than the structural units represented by the formulas (I) and (II). Such a structural unit is formed, for example, by ring-opening copolymerization of a cycloolefin monomer such as cyclobutene, cyclopentene, cycloheptene, or cyclooctene together with the cyclic olefin monomers (I ′) and (II ′). can do. In addition, in the presence of an unsaturated hydrocarbon polymer having an olefinically unsaturated bond in the main chain, such as polybutadiene, polyisoprene, styrene-butadiene copolymer, ethylene-nonconjugated diene copolymer, polynorbornene, etc. It can also be formed by ring-opening copolymerization of the olefinic monomers (I ′) and (II ′), and when having such a structural unit, the impact resistance of the copolymer of the present invention is as follows. Tend to be improved.

  However, in the present invention, it is preferable to carry out copolymerization using only the cyclic olefinic monomers (I ′) and (II ′). That is, the cyclic olefin polymer of the present invention may have other structural units in addition to the structural units represented by the formulas (I) and (II) as long as the object of the present invention is not impaired. However, it is preferable that there is no structural unit other than the structural units represented by the formulas (I) and (II).

  A ring-opening copolymer obtained by ring-opening copolymerization of each cyclic olefin monomer has an olefinic unsaturated bond in the molecule and has problems such as heat-resistant coloring. The olefinically unsaturated bond is preferably hydrogenated, but a known method can be applied to the hydrogenation reaction.

  For example, the catalyst, solvent, temperature conditions, etc. described in JP-A-63-218726, JP-A-1-132626, JP-A-1-240517, JP-A-2-10221 and the like are applied. The ring-opening polymerization reaction and the hydrogenation reaction can be carried out.

  The hydrogenation rate of the olefinically unsaturated bond is usually 80 mol% or more, preferably 90 mol% or more, more preferably 95 mol% or more, and particularly preferably 99 mol% or more. The hydrogenation reaction in the present invention is for olefinic unsaturated bonds in the molecule as described above. When the cyclic olefin polymer of the present invention has an aromatic group, the aromatic group is refracted. Since there may be an advantageous effect on optical characteristics such as the rate and heat resistance, hydrogenation is not necessarily required.

As the molecular weight of the cyclic olefin polymer of the present invention, the polystyrene-equivalent number average molecular weight (Mn) measured by gel permeation chromatography (GPC) is usually 3 × 10 ^{3 to} 5 × 10 ⁵ , preferably 5 × 10 ^{3 to} 3 × 10 ⁵ , more preferably 1 × 10 ⁴ to 2 × 10 ⁵ , and the weight average molecular weight (Mw) in terms of polystyrene is usually 5 × 10 ³ to 1 × 10 ⁶ , preferably It is desirable to be in the range of 1 × 10 ^{4 to} 5 × 10 ⁵ , more preferably 2 × 10 ⁴ to 4 × 10 ⁵ .

  If the molecular weight is too small, the strength of the resulting film may be low, or the retardation development property during stretching may be reduced. On the other hand, when the molecular weight is excessive, the solution viscosity and the melt viscosity become too high, and the productivity and processability of the copolymer of the present invention may be deteriorated.

Further, the molecular weight distribution (Mw / Mn) of the cyclic olefin polymer of the present invention is usually 1.5 to 10, preferably 2 to 7, and more preferably 2 to 5.
The cyclic olefin polymer of the present invention has a saturated water absorption at 23 ° C. of usually 0.05 to 1% by weight, preferably 0.07 to 0.8% by weight, more preferably 0.1 to 0.7% by weight. % Is desirable. When the saturated water absorption rate of the cyclic olefin polymer of the present invention is within the above range, various optical properties, transparency, retardation and uniformity of retardation, or dimensional accuracy of the obtained film are high temperature and high humidity. In addition to being stably maintained even under such conditions, it is excellent in adhesion and adhesion to other materials, so that peeling does not occur during use, and it is compatible with additives such as antioxidants. Since solubility is also favorable, the freedom degree of selection of the kind and addition amount of an additive becomes large.

  When this saturated water absorption is less than 0.05% by weight, the resulting film has low adhesion and adhesiveness to other materials, tends to cause peeling during use, and an antioxidant. The amount of additives such as these may be limited. On the other hand, when the saturated water absorption exceeds 1% by weight, the water absorption tends to cause changes in optical characteristics and dimensional changes.

Here, the saturated water absorption is a value obtained by immersing in water at 23 ° C. for 1 week and measuring an increased weight in accordance with ASTM D570.
The glass transition temperature (Tg) of the cyclic olefin polymer of the present invention is usually 70 to 250 ° C, preferably 90 to 200 ° C, more preferably 100 to 180 ° C. A Tg of 120 ° C. or higher is preferable because of having excellent heat resistance. When Tg is less than 90 ° C., the heat distortion temperature becomes low, which may cause a problem in heat resistance, and a problem that a change in optical characteristics due to temperature in the obtained film becomes large may occur. is there. On the other hand, when Tg exceeds 200 ° C., the processing temperature becomes too high during the stretching process, and the copolymer of the present invention may be thermally deteriorated, and productivity and workability may be deteriorated.

  Here, the Tg of the cyclic olefin polymer is the maximum peak temperature of the differential differential scanning calorimetry curve obtained when measured in a nitrogen atmosphere using a differential scanning calorimeter (DSC) at a heating rate of 20 ° C./min. (Point A) and a temperature of −20 ° C. from the maximum peak temperature (Point B) are plotted on the differential scanning calorimetry curve, and the intersection of the tangent line on the baseline starting from Point B and the tangent line starting from Point A As required.

Polymerization Catalyst Examples of the catalyst used in the production of the cyclic olefin polymer of the present invention include the catalysts described in Olefin Metathesis and Metathesis Polymerization (KJ IVIN, JC MOL, Academic Press 1997). Preferably used. Examples of such a catalyst include (i) (a) at least one selected from compounds of W, Mo, Re, V and Ti, and (b) an alkali metal element (for example, Li, Na, K). , Alkaline earth metal elements (for example, Mg, Ca), Group 12 elements (for example, Zn, Cd, Hg), Group 13 elements (for example, B, Al), Group 14 elements (for example, Si, Sn) , Pd) and the like, and a metathesis catalyst comprising a combination with at least one selected from those having at least one of the element-carbon bond or the element-hydrogen bond. In order to enhance the activity of the catalyst, the additive (c) described later may be added.

Specific examples of the component (a) include compounds described in JP-A-1-240517 such as WCl ₆ , MoCl ₅ , ReOCl ₃ , VOCl ₃ and TiCl ₄ . These can be used singly or in combination of two or more.

Specific examples of the component (b), for _{example, n-C 4 H 9 Li} , (C 2 H 5) 3 Al, (C 2 H 5) 2 AlCl, (C 2 H 5) 1.5 AlCl 1 And compounds described in JP-A-1-240517 such as _.5 , (C ₂ H ₅ ) AlCl ₂ , methylaluminoxane, and LiH. These can be used singly or in combination of two or more.

  As the additive of the component (c), for example, alcohols, aldehydes, ketones, amines and the like can be preferably used, and further, compounds described in JP-A-1-240517 can be used. Can do. These can be used singly or in combination of two or more.

  The amount of the metathesis catalyst used in combination with the component (a) is such that the molar ratio of the component (a) to the total monomer is usually 1 : 500 to 1: 500,000, preferably 1: 1,000 to 1: 100,000. Further, the ratio of the component (a) to the component (b) is such that the metal atom (mole) ratio of “(a) :( b)” is usually 1: 1 to 1:50, preferably 1: 2. It is in the range of ˜1: 30. When the additive (c) is added to the metathesis catalyst, the ratio of the component (a) to the component (c) is such that the molar ratio of “(c) :( a)” is usually 0.005: 1 to The range is 15: 1, preferably 0.05: 1 to 7: 1.

As other catalysts,
(Ii) A metathesis catalyst comprising a transition metal-carbene complex or a metallacyclobutane complex belonging to Groups 4 to 8 of the periodic table can be used.

Specific examples of the catalyst (ii), for _{^{example, W (= N-2,6-}} C 6 H 3 i Pr 2) (= CH tert Bu) (O tert Bu) 2, Mo (= N-2, 6-C ₆ H ₃ ⁱ Pr ₂ ) (= CH ^tert Bu) (O ^tert Bu) ₂ , Ru (= CHCH = CPh ₂ ) (PPh ₃ ) ₂ Cl ₂ , Ru (= CHPh) [P (C ₆ H ₁₁ ) ₃ ] ₂ Cl _{2 and the} like. These can be used singly or in combination of two or more.

  The amount of the catalyst (ii) used is such that the molar ratio of “catalyst (ii): total monomer” is usually 1: 500 to 1: 50,000, preferably 1: 100 to 1:10, 000.

The catalysts (i) and (ii) may be used in combination.
The molecular weight of the copolymer used in the present invention can be adjusted by adjusting the polymerization temperature, the type of catalyst, the type of solvent, etc., but the molecular weight regulator is allowed to coexist in the reaction system for ring-opening copolymerization. It is preferable to adjust by this. As the molecular weight regulator, for example, α-olefins such as ethylene, propene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene and styrene are preferable, Of these, 1-butene and 1-hexene are particularly preferred. These molecular weight regulators can be used singly or in combination of two or more. The amount of the molecular weight regulator used is usually 0.005 to 0.6 mol, preferably 0.02 to 0.5 mol, per mol of all monomers.

  Examples of the solvent used in the ring-opening copolymerization reaction (that is, a solvent that dissolves a monomer, a ring-opening polymerization catalyst, a molecular weight regulator, etc.) include alkanes such as pentane, hexane, heptane, octane, nonane, and decane. ; Cycloalkanes such as cyclohexane, cycloheptane, cyclooctane, decalin, norbornane; aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, cumene; chlorobutane, bromohexane, methylene chloride, dichloroethane, hexamethylene dibromide, chlorobenzene , Compounds such as halogenated alkanes such as chloroform and tetrachloroethylene, aryl halides; saturated carboxylic acid esters such as ethyl acetate, n-butyl acetate, isobutyl acetate, methyl propionate; dibutyl ether Tetrahydrofuran, include ethers such as dimethoxyethane, aromatic hydrocarbons are preferred among these. These can be used singly or in combination of two or more. The use amount of the solvent for the ring-opening polymerization reaction is such that the weight ratio of “solvent: total monomer” is usually 1: 1 to 10: 1, preferably 1: 1 to 5: 1. Is desirable.

  The temperature of the monomer solution when adding the catalyst is preferably 30 to 200 ° C, more preferably 50 to 180 ° C. When the temperature is lower than 30 ° C, the yield of the polymer may be lowered, and when it exceeds 200 ° C, it may be difficult to control the molecular weight.

The reaction time for carrying out the ring-opening copolymerization reaction is usually 0.1 to 10 hours, preferably 0.1 to 9 hours, more preferably 0.1 to 8 hours.
A ring-opening copolymer obtained by ring-opening copolymerization of each cyclic olefin monomer has an olefinic unsaturated bond in the molecule and has problems such as heat-resistant coloring. The olefinically unsaturated bond is preferably hydrogenated. The hydrogenation method and the preferred hydrogenation rate are as described above.

<Additives>
Various additives can be blended with the cyclic olefin polymer of the present invention as required. For example, an antioxidant selected from a phenolic antioxidant, a lactone antioxidant, a phosphorus antioxidant and a sulfur antioxidant may be added to improve oxidation stability and prevent coloring and deterioration. it can. The antioxidant may be blended at a ratio of 0.001 to 5 parts by weight per 100 parts by weight of the polymer. Specific examples of antioxidants include
1) 2,6-di-tert-butyl-4-methylphenol, 4,4′-thiobis- (6-tert-butyl-3-methyl-phenyl), 1,1-bis (4-hydroxyphenyl) cyclohexane 2,2′-methylenebis (4-ethyl-6-tert-butylphenol), tetrakis [methylene-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] methane, 3- (3 5-di-tert-butyl-4-hydroxyphenyl) propionic acid stearate, 2,5-di-tert-butylhydroquinone and pentaerythrityl-tetrakis [3- (3,5-di-tert-butyl-4- Hydroxyphenyl)] propionate and other phenolic antioxidants or hydroquinone antioxidants,
2) Bis (2,6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphite, tris (2,4-di-tert-butylphenyl) phosphite, tetrakis (2,4-di-tert) -Butyl-5-methylphenyl) 4,4'-biphenylenediphosphonite, 3,5-di-tert-butyl-4-hydroxybenzylphosphonate-diethyl ester, bis (2,4-di-tert-butylphenyl) Phosphorous secondary antioxidants such as pentaerythritol diphosphite, tris (4-methoxy-3,5-diphenyl) phosphite and tris (nonylphenyl) phosphite, and 3) dilauryl-3,3′-thiodipro Sulfur-based secondary antioxidants such as pionate and 2-mercaptobenzimidazole It can gel.

  Moreover, a flame retardant can also be mix | blended with the cyclic olefin type polymer of this invention. A well-known thing can be used as a flame retardant, For example, a halogen flame retardant, an antimony flame retardant, a phosphate ester flame retardant, a metal hydroxide, etc. can be mentioned. Among these, phosphate ester-based flame retardants that are effective with a small amount of blending and can minimize deterioration of water absorption, low dielectric constant, and transparency are preferable, and 1,3-bis (phenylphosphoryl) benzene, 1 , 3-bis (diphenylphosphoryl) benzene, 1,3-bis [di (alkylphenyl) phosphoryl] benzene, 1,3-bis [di (2 ′, 6′-dimethylphenyl) phosphoryl] benzene, 1,3- Bis [di (2 ′, 6′-diethylphenyl) phosphoryl] benzene, 1,3-bis [di (2 ′, 6′-diisopropylphenyl) phosphoryl] benzene, 1,3-bis [di (2 ′, 6) '-Dibutylphenyl) phosphoryl] benzene, 1,3-bis [di (2'-tert-butylphenyl) phosphoryl] benzene, 1,3-bis [di (2'-isopropyl) Ruphenyl) phosphoryl] benzene 1,3-bis [di (2′-methylphenyl) phosphoryl] benzene, 1,4-bis (diphenylphosphoryl) benzene, 1,4-bis [di (2 ′, 6′-dimethylphenyl) ) Phosphoryl] benzene, 1,4-bis [di (2 ′, 6′-diethylphenyl) phosphoryl] benzene, 1,4-bis [di (2 ′, 6′-diisopropylphenyl) phosphoryl] benzene, 1,4 -Bis [di (2'-tert-butylphenyl) phosphoryl] benzene, 1,4-bis [di (2'-isopropylphenyl) phosphoryl] benzene, 1,4-bis [di (2'-methylphenyl) phosphoryl ] Condensed phosphoric acid such as benzene and 4,4′-bis [di (2 ″, 6 ″ -dimethylphenyl) phosphorylphenyl] dimethylmethane Ester-based flame retardant is more preferable. The blending amount depends on the selected flame retardant and the required degree of flame retardancy, but is preferably 0.5 to 40 parts by weight, more preferably 2 to 30 parts by weight, based on 100 parts by weight of the cyclic olefin polymer. -20 parts by weight is particularly preferred. When the amount of the flame retardant is less than 0.5 parts by weight, the effect is insufficient. On the other hand, when the amount exceeds 40 parts by weight, transparency is impaired, and electrical characteristics such as dielectric constant are deteriorated. Or the water absorption increases or the heat resistance deteriorates.

  If necessary, the cyclic olefin polymer of the present invention further includes an antioxidant, a heat stabilizer, a light stabilizer, a phase difference adjusting agent, an ultraviolet absorber, an antistatic agent, a dispersant, a processability improver, Chlorine scavenger, flame retardant, crystallization nucleating agent, anti-blocking agent, anti-fogging agent, mold release agent, pigment, organic or inorganic filler, neutralizing agent, lubricant, decomposition agent, metal deactivator, contamination prevention Known additives such as materials, antibacterial agents, other resins, and thermoplastic elastomers can be added as long as the effects of the invention are not impaired.

<Manufacture of raw film>
The raw film used for producing the retardation film of the present invention is obtained by forming a film, a sheet, or the like by dissolving the cyclic olefin polymer in an appropriate solvent and casting it. It can also be obtained by forming a film by a known method such as a melt extrusion method.

The obtained raw film is excellent in balance in optical properties such as transparency, chemical resistance, heat resistance, water resistance and moisture resistance.
The raw film has a film thickness of 100 to 250 μm, preferably 120 to 200 μm, and the difference between the maximum thickness and the minimum thickness of the film is within 3 μm, preferably within 2 μm.

<Manufacture of retardation film>
The retardation film of the present invention can be suitably obtained by transversely uniaxially stretching a raw film at the above stretching ratio.

In order to obtain the retardation film of the present invention, a step of subjecting the raw film to a heat stretching treatment is required.
The temperature at which the heat-stretching treatment is performed is usually in the range of (Tg-10 ° C.) to (Tg + 70 ° C.) based on the glass transition temperature (Tg) of the raw film made of the cyclic olefin polymer used in the present invention. Yes, preferably in the range of (Tg ± 0 ° C.) to (Tg + 50 ° C.). The above range is preferable because the film can be stretched without causing thermal deterioration and without breaking. Here, Tg is a value obtained using the above-described differential scanning calorimeter (DSC).

  The stretching is desirably tenter transverse uniaxial stretching (uniaxial stretching in the width direction). By extending the film uniaxially, the in-plane maximum refractive index becomes the film width direction, and roll-to-roll bonding is possible when bonding with a polarizer, thereby improving productivity. The transverse uniaxial stretching is performed in an oven in which the temperature distribution is controlled within a set temperature ± 0.5 ° C, preferably within a set temperature ± 0.3 ° C, more preferably within a set temperature ± 0.2 ° C. , NZ and the optical axis are desirable for accurately controlling the optical characteristics.

  Here, the set temperature of the horizontal uniaxial stretching may be the same temperature in all regions in the oven, or may be a temperature in which distribution is provided stepwise or in a gradient manner. When the set temperature is a temperature having a distribution, the actual temperature distribution in the oven and the set temperature distribution are within ± 0.5 ° C, preferably within ± 0.3 ° C, more preferably It is desirable to be within ± 0.2 ° C.

  The stretching speed of the lateral uniaxial stretching is, for example, in the range of 2 to 100 m / min, preferably 5 to 50 m / min. The draw ratio and the number of draws are appropriately selected depending on the desired retardation value. The draw ratio is 2.5 to 5.5 times, preferably 2.8 to 5.4 times, particularly preferably 3.0 to 5.3 times.

The number of stretching is 1 to 2 times.
In the present invention, it is preferable to perform transverse uniaxial stretching twice, for example, when the stretching ratio exceeds 4 times at a high magnification, in order to ensure the uniformity of thickness and retardation after stretching, When the uniformity of thickness and retardation can be obtained, it is more preferable that the number of stretching is one. In addition, the draw ratio in the case of performing transverse uniaxial stretching twice is represented by the product of the first draw ratio and the second draw ratio.

The thickness of the retardation film of the present invention is 20 to 100 μm, preferably 25 to 90 μm. Further, the difference between the maximum thickness and the minimum thickness of the film is within 3 μm.
As mentioned above, selection of copolymerization monomers (I ′) and (II ′) and copolymerization ratio, adjustment of molecular weight in polymerization reaction, Tg of copolymer, film thickness and stretching ratio are within the above preferred ranges. Thus, α (MD) and α (TD) of the retardation film can be controlled within a preferable range, an excessive dimensional change during heating and anisotropy of the dimensional change are prevented, and the retardation film is used as a polarizing film. It is possible to reduce warpage and undulation of the polarizing plate laminated on at least one side of the film.

<Application>
The retardation film of the present invention has excellent transparency and heat resistance and low water absorption, and the polarizing plate formed by laminating the retardation film has little warpage and undulation, so that the polarizing plate can be manufactured and the liquid crystal In addition to being easy to handle in the manufacture of display elements, the liquid crystal display elements are excellent in uniformity, stability and high definition. Therefore, it can be suitably used for various liquid crystal display elements, in particular, a vertical alignment type liquid crystal display element, and enables good viewing angle compensation.

  Specific examples of the present invention will be described below, but the present invention is not limited to these examples. In the following, “parts” and “%” mean “parts by weight” and “% by weight” unless otherwise specified.

Moreover, each evaluation item in the following Examples was measured by the following method.
<Glass transition temperature (Tg)>
Maximum differential peak temperature (point A) and maximum peak temperature of differential differential scanning calorimetry curve obtained when measured in a nitrogen atmosphere using a differential scanning calorimeter (DSC) manufactured by Seiko Instruments Inc. Further, a temperature of −20 ° C. (point B) was plotted on the differential scanning calorific value curve, and obtained as an intersection of a tangent line on the base line starting from point B and a tangent line starting from point A.

<Saturated water absorption>
In accordance with ASTM D570, the sample was immersed in water at 23 ° C. for 1 week, the change in the weight of the sample before and after immersion was measured, and the saturated water absorption was determined from the value.

<Total light transmittance>
Measurement was performed using a haze meter “HGM-2DP type” manufactured by Suga Test Instruments Co., Ltd.
<Phase difference of transmitted light>
The phase differences Re and NZ at a wavelength of 589 nm were measured using “KOBRA-21ADH” manufactured by Oji Scientific Instruments.

<Logarithmic viscosity>
Using an Ubbelohde viscometer, measurement was performed at 30 ° C. in chloroform or cyclohexane (sample concentration: 0.5 g / dL).

<Weight average molecular weight and number average molecular weight>
By gel permeation chromatography (GPC) (HLC-8020, manufactured by Tosoh Corporation), using tetrahydrofuran (THF) solvent, polystyrene equivalent weight average molecular weight (Mw), number average molecular weight (Mn), molecular weight distribution (Mw / Mn) was measured.

<Average linear expansion coefficient>
Using an “TMA-SS6000” manufactured by Seiko Instruments Inc., an average linear expansion coefficient (−40 ° C. to 85 ° C.) at an elongation mode, a load of 1 g, a film width of 4 mm, a chuck width of 20 mm, and a temperature increase of 10 ° C./min ( α (MD) and α (TD)) were measured.

<Synthesis Example 1>
8-methyl-8-methoxycarbonyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene (specific monomer) 250 parts, 1-hexene (molecular weight regulator) 18 parts, toluene (ring-opening polymerization reaction solvent) 750 parts, a nitrogen-substituted reaction vessel The solution was heated to 60 ° C. Next, in the solution in the reaction vessel, as a polymerization catalyst, 0.62 part of a toluene solution of triethylaluminum (1.5 mol / liter), tungsten hexachloride modified with tert-butanol and methanol (tert-butanol: methanol: tungsten) = 3.75 mol: 0.3 mol: 1 mol) of a toluene solution (concentration 0.05 mol / liter) 3.7 parts was added, and this solution was heated and stirred at 80 ° C. for 3 hours to cause a ring-opening polymerization reaction. A ring-opening polymer solution was obtained. The polymerization conversion rate in this polymerization reaction was 97%.

1,000 parts of the ring-opening polymer solution thus obtained was charged into an autoclave, and 0.12 part of RuHCl (CO) [P (C ₆ H ₅ ) ₃ ] ₃ was added to the ring-opening polymer solution. Then, the hydrogenation reaction was performed by heating and stirring for 3 hours under the conditions of a hydrogen gas pressure of 100 kg / cm ² and a reaction temperature of 165 ° C. After cooling the obtained reaction solution (hydrogenated polymer solution), the hydrogen gas was released. This reaction solution was poured into a large amount of methanol to separate and recover a coagulated product, which was dried to obtain a hydrogenated polymer (hereinafter referred to as “resin A”).

The hydrogenation rate measured by ¹ H-NMR of the resin A thus obtained was 99.9%, the glass transition temperature (Tg) measured by the DSC method was 165 ° C., and the number in terms of polystyrene measured by the GPC method. The average molecular weight (Mn) is 32,000, the weight average molecular weight (Mw) is 137,000, the molecular weight distribution (Mw / Mn) is 4.29, the saturated water absorption at 23 ° C. is 0.3%, and in chloroform at 30 ° C. The logarithmic viscosity was 0.78 dl / g.

<Synthesis Example 2>
8-methyl-8-methoxycarbonyltetracyclo [4.4.0.1 ^2,5 . Synthesis Example, except that 215 parts of ^{17, 10} ] -3-dodecene and 35 parts of bicyclo [2.2.1] hept-2-ene were used and the addition amount of 1-hexene was 30 parts. In the same manner as in Example 1, a hydrogenated polymer (hereinafter referred to as “resin B”) was obtained.

The hydrogenation rate measured by ¹ H-NMR of the resin B thus obtained was 99.9%, the Tg measured by the DSC method was 125 ° C., the Mn in terms of polystyrene measured by the GPC method was 46,000, The Mw was 190,000 and the Mw / Mn was 4.15, the saturated water absorption at 23 ° C. was 0.18%, and the logarithmic viscosity in chloroform at 30 ° C. was 0.53 dl / g.

<Synthesis Example 3>
Tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene 53 parts and 8-ethylidenetetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene 46 parts and tricyclo [4.3.0.1 ^2,5 ] -deca-3,7-diene 66 parts, the addition amount of 1-hexene is 18 parts A hydrogenated polymer (hereinafter referred to as “resin C”) was obtained in the same manner as in Synthesis Example 1 except that cyclohexane was used in place of toluene as a solvent for the ring-opening polymerization reaction.

  The hydrogenation rate of the obtained resin C was 99.9%, Tg measured by DSC method was 137 ° C., Mn measured by GPC method (solvent: o-dichlorobenzene) was 39,000, Mw was 158,000 and Mw / Mn was 4.05, the saturated water absorption at 23 ° C. was 0.01%, and the logarithmic viscosity in chloroform at 30 ° C. was 0.70 dl / g.

<Production Example 1>
Production of Resin Film (A-1) Resin A is dissolved in toluene at a concentration of 30% (solution viscosity at room temperature is 30,000 mPa · s), and pentaerythrityl tetrakis [3- ( 3,5-di-tert-butyl-4-hydroxyphenyl) propionate] is added in an amount of 0.1 part by weight based on 100 parts by weight of the resin, and a differential pressure using a metal fiber sintered filter made by Nippon Pole with a pore diameter of 5 μm is used. The solution was filtered while controlling the flow rate of the solution so as to be within 0.4 MPa. A PET film (100 μm thick) obtained by subjecting the resulting solution to a hydrophilic (easy-to-adhesive) surface treatment with an acrylic acid system using “INVEX Lab Coater” manufactured by Inoue Metal Industry installed in a Class 1000 clean room ( The film was dried on Toray Co., Ltd. “Lumirror U94” so that the film thickness after drying was 130 μm, and this was subjected to primary drying at 50 ° C. and then secondary drying at 90 ° C. When the PET film was peeled off, a resin film (A-1) was obtained. The total light transmittance of the obtained resin film (A-1) was 93%.

<Production Example 2>
Production of Resin Film (B-1) A resin film (B-1) having a thickness of 150 μm was obtained in the same manner as in Production Example 1 except that resin B was used instead of resin A. The total light transmittance of the obtained resin film (B-1) was 93%.

<Production Example 3>
Production of Resin Film (C-1) A resin film (C-1) having a thickness of 150 μm was prepared in the same manner as in Production Example 1 except that resin C was used instead of resin A and cyclohexane was used instead of toluene. ) The total light transmittance of the obtained resin film (C-1) was 93%.

<Production Example 4>
Production of Resin Film (B-2) Resin A was extruded downstream with a gear pump using a twin screw extruder (TEM-48, manufactured by Toshiba Machine Co., Ltd.) and Nippon Seisen with a nominal opening of 10 μm Using a metal fiber sintered filter, melt filtration is performed, and a coat hanger type T die (650 mm width) is used to extrude into a film at 280 ° C. with a gap of 0.5 mm at the exit of the T die, and a cooling roll The film (B-2) having a thickness of 150 μm was obtained. The total light transmittance of the obtained film (B-2) was 93%.

<Production Example 5>
Production of Resin Film (C-2) A resin film (C-2) having a thickness of 150 μm was obtained by the same method as in Production Example 4 except that Resin C was used instead of Resin A. The total resin transmittance of the obtained resin film (C-2) was 93%.

[Example 1]
Production of Retardation Film (A-11) The resin film (A-1) is stretched uniaxially at 180 ° C. and 2.5 times by a tenter-type transverse stretching machine, thereby having a film thickness of 51 to 53 μm. A retardation film (A-11) was obtained. Re of the obtained stretched film was 155 nm, and NZ was 1.40. The average linear expansion coefficient (α (TD)) in the stretching direction (film width direction) is 60 ppm / ° C., and the average linear expansion coefficient (α (MD)) in the direction orthogonal to the stretching direction (film longitudinal direction) is 72 ppm / ° C. ° C.

[Example 2]
Production of Retardation Film (B-11) The resin film (B-1) is uniaxially stretched at 147 ° C. and 3.0 times to obtain a retardation film (B-11) having a film thickness of 47 to 50 μm. Obtained. The stretched film obtained had Re of 105 nm and NZ of 1.35. Further, α (TD) was 74 ppm / ° C., and α (MD) was 85 ppm / ° C.

[Example 3]
Production of Retardation Film (B-21) Retardation with a film thickness of 48 to 51 μm by the same method as in Example 2 except that resin film (B-2) was used instead of resin film (B-1). A film (B-21) was obtained. Moreover, Re of the obtained stretched film was 155 nm, and NZ was 1.35. α (TD) was 72 ppm / ° C., and α (MD) was 86 ppm / ° C.

[Example 4]
Production of Retardation Film (B-22) The resin film (B-2) is transversely uniaxially stretched at 133 ° C. and 2.0 times, and this film is further transversely uniaxially stretched at 147 ° C. and 2.4 times. Thus, a retardation film (B-22) having a net stretching of 4.8 times and a film thickness of 30 to 33 μm was obtained. Re of the obtained stretched film was 150 nm, and NZ was 1.20. Further, α (TD) was 74 ppm / ° C., and α (MD) was 87 ppm / ° C.

[Example 5]
Production of Retardation Film (C-11) The resin film (C-1) was horizontally stretched at 157 ° C. and 3.0 times to obtain a stretched film (C-11) having a film thickness of 49 to 52 μm. . Re of the obtained stretched film was 160 nm, and NZ was 1.33. Further, α (TD) was 63 ppm / ° C., and α (MD) was 70 ppm / ° C.

[Example 6]
Manufacture of retardation film (C-21) Using resin film (C-2) instead of resin film (C-1), by transverse stretching at 160 ° C. and 3.0 times setting, film thickness 48-51 μm Of retardation film (C-21) was obtained. Re of the obtained stretched film was 142 nm, and NZ was 1.34. Further, α (TD) was 68 ppm / ° C., and α (MD) was 74 ppm / ° C.

[Comparative Example 1]
Stretched film (A-12)
The resin film (A-1) was longitudinally stretched 2.7 times at 185 ° C. to obtain a stretched film (A-12) having a thickness of 75 to 77 μm. The obtained stretched film had Re of 400 nm and NZ of 1.03. Further, α (TD) was 92 ppm / ° C., and α (MD) was 58 ppm / ° C.

<Production Example 6>
Production of Polarizing Film Polyvinyl alcohol (hereinafter referred to as “PVA”) was dyed in a dyeing bath comprising an aqueous solution having an iodine concentration of 0.03% and a potassium iodide concentration of 0.5% (temperature: 30 ° C.). A pre-stretching process is performed at a stretching ratio of 3 times, and then a post-stretching process is performed at a stretching ratio of 2 in a cross-linking bath composed of an aqueous solution having a boric acid concentration of 5% and a potassium iodide concentration of 8%. Then, a polarizing film (hereinafter also referred to as “polarizer”) was obtained by performing a drying treatment.

<Preparation example>
Preparation of aqueous adhesive 4% aqueous solution of PVA resin (trade name: 163-03045 (molecular weight 500, saponification degree: about 88 mol%), manufactured by Wako Pure Chemical Industries, Ltd.) was prepared . On the other hand, 100 parts of polyurethane adhesive (trade name: WLS-201 (non-volatile content 35%), manufactured by Dainippon Ink & Chemicals, Inc.) is added to a polyepoxy curing agent (trade name: CR-5L (active ingredient 100). % Product), Dainippon Ink & Chemicals, Inc.) 5 parts. The obtained PVA aqueous solution and polyurethane resin were mixed at a solid weight ratio of 20:80, and then diluted with water to prepare a 15% mixed aqueous solution (aqueous adhesive).

[Example 7]
Production of Polarizing Plate (A-111) One side of an A4-size retardation film (A-11) is subjected to corona treatment at an output of 60 W / m ² / min, and the corona-treated surface and the polarizer are stretched with respect to each other. The above water-based adhesive was applied so that the directions were orthogonal to each other, and the polarizer was dried at 50 ° C. for 3 minutes and then at 80 ° C. for 20 minutes with the drawing direction fixed by a mold. Subsequently, a triacetyl cellulose (TAC) film was attached to the other surface of the polarizer using a PVA adhesive and dried in the same manner to obtain a polarizing plate (A-111).

The transmittance of the obtained polarizing plate was 43.7%, and the degree of polarization was 99.9%. When it was removed from the mold and this polarizing plate was allowed to stand on a flat surface, the float at the end of the film was about 7 mm.
[Example 8]
Production of Polarizing Plate (B-111) A polarizing plate (B-111) was obtained in the same manner as in Example 7 except that the oriented film (B-11) was used instead of the oriented film (A-11). It was.

The transmittance of the obtained polarizing plate was 43.5%, and the degree of polarization was 99.9%. When the film was removed from the mold and the polarizing plate was allowed to stand on a flat surface, the film edge lifted about 8 mm.
[Example 9]
Production of Polarizing Plate (B-211) A polarizing plate (B-211) was obtained in the same manner as in Example 7 except that the oriented film (B-21) was used instead of the oriented film (A-11). It was.

The transmittance of the obtained polarizing plate was 43.6%, and the degree of polarization was 99.9%. When the film was removed from the mold and the polarizing plate was allowed to stand on a flat surface, the float at the end of the film was about 10 mm.
[Example 10]
Preparation of Polarizing Plate (B-221) A polarizing plate (B--) was prepared in the same manner as the polarizing plate (A-111) except that the oriented film (B-22) was used instead of the oriented film (A-11). 221) was obtained.

The transmittance of the obtained polarizing plate was 43.6%, and the degree of polarization was 99.9%. When the film was removed from the mold and the polarizing plate was allowed to stand on a flat surface, the float at the end of the film was about 15 mm.
[Example 11]
Production of Polarizing Plate (C-111) A polarizing plate (C-111) was obtained in the same manner as in Example 7 except that the oriented film (C-11) was used instead of the oriented film (A-11). It was.

The polarizing plate obtained had a transmittance of 43.4% and a degree of polarization of 99.9%. When it was removed from the mold and this polarizing plate was allowed to stand on a flat surface, the float at the end of the film was about 7 mm.
[Example 12]
Production of Polarizing Plate (C-211) A polarizing plate (C-211) was obtained in the same manner as in Example 7 except that the oriented film (C-21) was used instead of the oriented film (A-11). It was.

The transmittance of the obtained polarizing plate was 43.6%, and the degree of polarization was 99.9%. When it was removed from the mold and this polarizing plate was allowed to stand on a flat surface, the float at the end of the film was about 7 mm.
[Comparative Example 2]
Production of Polarizing Plate (A-121) A polarizing plate (A-121) was obtained in the same manner as in Example 7 except that the oriented film (A-12) was used instead of the oriented film (A-11). It was.

  The transmittance of the obtained polarizing plate was 43.7%, and the degree of polarization was 99.9%. When the film was removed from the mold and the polarizing plate was allowed to stand on a flat surface, the film curled and became cylindrical.

Industrial applicability

  The retardation film of the present invention is excellent in uniformity and stability, and has little warpage after bonding with a polarizing film, etc., so it is suitably used for the production of polarizing plates, mobile phones, notebook computers, car navigation systems, It can be suitably used for various liquid crystal display devices such as portable game machines, liquid crystal televisions, and liquid crystal monitors with large displays.

Claims (5)

A retardation film comprising a cyclic olefin polymer and satisfying the following formulas (1) to (5).
(1) 70 nm ≦ Re ≦ 300 nm
(2) 1.1 ≦ NZ ≦ 1.7
(In the formulas (1) and (2), Re is the in-plane retardation of the film at a wavelength of 589 nm, and is represented by Re = (nx−ny) × d, and NZ is NZ = (nx−nz). / (Nx−ny) where nx is the maximum refractive index in the film plane, ny is the refractive index in the direction perpendicular to nx in the film plane, and nz is relative to nx and ny. The refractive index in the film thickness direction orthogonal to each other, d represents the thickness (nm) of the film.)
(3) α (MD) ≦ 90 ppm / ° C.
(4) α (TD) ≦ 90 ppm / ° C.
(5) | α (MD) −α (TD) | ≦ 30 ppm / ° C.
(In the formulas (3) to (5), α (MD) represents an average linear expansion coefficient in the film longitudinal direction, and α (TD) represents an average linear expansion coefficient in the film width direction. However, the average linear expansion coefficient Are all values at −40 ° C. to 85 ° C.) The retardation film according to claim 1, wherein the cyclic olefin polymer has a structural unit represented by the following formula (I).

[In the formula (I), m is an integer of 1 or more, p is 0 or an integer of 1 or more, D is a group represented by —CH═CH— or —CH ₂ CH ₂ —, R ^{1 to} R ⁴ are each independently a hydrogen atom; a halogen atom; a linking group containing an oxygen atom, a sulfur atom, a nitrogen atom or a silicon atom; a substituted or unsubstituted hydrocarbon group having 1 to 30 carbon atoms; a polar group Represents an atom or group selected from the group, R ¹ and R ² may be combined to form a divalent hydrocarbon group, and R ³ and R ⁴ may be combined to form a divalent hydrocarbon group. May be. R ¹ and R ² may be bonded to each other to form a carbocyclic or heterocyclic ring, and R ³ and R ⁴ may be bonded to each other to form a carbocyclic or heterocyclic ring. May be monocyclic or polycyclic. ]   2. The retardation film according to claim 1, wherein the film thickness is 20 to 100 μm, and the difference between the maximum thickness and the minimum thickness of the film is within 3 μm.   A raw film of a cyclic olefin polymer having a film thickness of 100 to 250 μm and a difference between the maximum thickness and the minimum thickness of the film within 3 μm is placed so that the draw ratio is 2.5 to 5.5 times. A method for producing a retardation film, wherein the retardation film according to claim 1 is obtained by uniaxial stretching.   A retardation film according to claim 1, wherein the retardation film according to claim 1 is laminated on at least one side of the polarizing film.