JP2008257231A - Manufacturing method of negative a plate, negative a plate, polarizing plate and liquid crystal display apparatus using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a novel method for manufacturing a negative A plate with high productivity. <P>SOLUTION: The manufacturing method of the negative A plate is characterized by containing stretching of a film in a width direction which orthogonally crosses a transportation direction and also performing contraction in the transportation direction while transporting the film formed of one layer or two layers or more containing a material with negative proper double refraction value. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a novel method for producing a negative A plate. The present invention also relates to a novel negative A plate, a polarizing plate, and a liquid crystal display device using the same.

A liquid crystal display (LCD) has a liquid crystal cell and a polarizing plate. The polarizing plate generally has a protective film made of cellulose acetate and a polarizing layer. For example, a polarizing layer made of a polyvinyl alcohol film is dyed with iodine, stretched, and both surfaces thereof are laminated with a protective film. Obtained.
In a transmissive liquid crystal display device, polarizing plates are attached to both sides of a liquid crystal cell, and one or more retardation films (hereinafter sometimes referred to as optical compensation films) may be disposed.
In a reflection type liquid crystal display device, usually, a reflector, a liquid crystal cell, one or more retardation films, and a polarizing plate are arranged in this order. The liquid crystal cell includes a liquid crystal molecule, two substrates for encapsulating the liquid crystal molecule, and an electrode layer for applying a voltage to the liquid crystal molecule.
The liquid crystal cell performs ON / OFF display depending on the alignment state of liquid crystal molecules, and can be applied to both transmission and reflection types. TN (Twisted Nematic), IPS (In-Plane Switching), OCB (Optically Compensatory Bend). ), VA (Vertically Aligned), and ECB (Electrically Controlled Birefringence) have been proposed.

Among such LCDs, for applications that require high display quality, a 90 degree twisted nematic liquid crystal display device (hereinafter referred to as TN mode) that uses nematic liquid crystal molecules having positive dielectric anisotropy and is driven by a thin film transistor. Is mainly used.
However, although the TN mode has excellent display characteristics when viewed from the front, the contrast is lowered when viewed from an oblique direction, and display is caused by gradation inversion in which the brightness is reversed in gradation display. There is a viewing angle characteristic that the characteristic is deteriorated, and this improvement is strongly desired.

  On the other hand, the liquid crystal systems with wide viewing angles such as the IPS system, OCB system, and VA system have expanded their share with the recent increase in demand for liquid crystal televisions. Each system has improved display quality year by year, but the problem of color misregistration that occurs when viewed obliquely has not been solved.

  In order to solve such a problem of color misregistration, an optical compensation method using a negative A plate in the IPS method is disclosed. For example, Patent Document 1 discloses an optical compensation method using a negative A plate having an in-plane retardation Re of 90 nm. Patent Document 2 discloses another optical compensation method using a negative A plate having an in-plane retardation Re of 195 nm.

  As the negative A plate that can be used in such an optical compensation system, a negative A plate using a stretched film and a negative A plate using a coating film are mainly cited. A negative A plate using a stretched film is formed by stretching an unstretched film formed of a polymer material having a negative intrinsic birefringence value. A negative A plate using a coating film is formed by applying discotic liquid crystal molecules having a polymerizable group on a substrate film, and then immobilizing it after homogenous alignment.

  Regarding the IPS method for solving the color misregistration, various optical compensation methods using other retardation films have already been proposed in addition to the negative A plate. Among them, a specific optical compensation method is adopted especially for TV applications, and in order to survive without being deceived, the optical compensation method can improve color shift more accurately and at the same time has high productivity. It is necessary to be.

When a retardation film including a negative A plate is used for optical compensation such as an IPS system, it is disposed between a liquid crystal cell and a polarizer. At this time, it is preferable that the retardation film also serves as a protective film for the polarizing layer from the viewpoint of productivity as well as thinning and resource saving of the panel on which the retardation film is mounted.
When the retardation film is used as a protective film for the polarizer, it is necessary to continuously bond the polarizing layer and the protective film with a roll-to-roll, and when using a negative A plate as the protective film, optical compensation From this point of view, the slow axis must be parallel to the absorption axis of the polarizer.
At present, the polarizing layer is mainly produced by stretching a polyvinyl alcohol film dyed with iodine in the length direction, and the absorption axis is parallel to the length direction. Therefore, it is necessary that the slow axis of the negative A plate is also parallel to the length direction. However, the negative A plate having the slow axis in the length direction and capable of precisely performing optical compensation is provided. It is difficult to make.

In Patent Document 3, at least one surface of a layer containing a material having a negative intrinsic birefringence value as a main component is at least 20 ° C. lower than the glass transition temperature Tg _A of the material having a negative intrinsic birefringence value. A layer comprising a transparent resin having a glass transition temperature Tg _B as a main component is laminated to obtain an unstretched laminate, which is stretched at a temperature of Tg _A −10 (° C.) to Tg _A +20 (° C.). A method for producing an optical laminate having excellent retardation control characteristics and predetermined optical characteristics is disclosed.

Patent Document 4 relates to a liquid crystal display device having a negative uniaxial retardation film, and the negative uniaxial retardation film is produced by stretching an unstretched film having negative intrinsic birefringence. It is described that it is possible, and above all, it is possible to bond the retardation film and the polarizing layer by roll-to-roll by stretching in the free end longitudinal uniaxial direction, which is preferable from the viewpoint of productivity (Patent Literature). 4 [0054]). However, when an unstretched film having negative intrinsic birefringence is stretched uniaxially at the free end, the in-plane slow axis of the film appears in the transverse direction, and the in-plane slow axis of the retardation film and the absorption axis of the polarizing film It is difficult to match with a roll-to-roll.
In addition, in order to make the in-plane slow axis of the retardation film in the longitudinal direction, free end transverse stretching is required, but in the case of a long film, the lateral end is fixed in order to transport the film in the longitudinal direction. Therefore, it does not become a free end, and therefore it is extremely difficult to produce a free end transverse stretch with a long film.
JP-A-2005-173584 JP 2005-309379 A JP 2004-133313 A JP 2005-221532 A

An object of the present invention is to solve the conventional problems and achieve the following objects. That is, an object of the present invention is to provide a novel method capable of producing a negative A plate with high productivity.
In addition, the present invention is a negative A plate that is highly productive, can accurately compensate the liquid crystal cell optically, and can contribute to improving contrast and reducing color shift depending on the viewing angle direction during black display. And providing a polarizing plate.
It is another object of the present invention to provide a liquid crystal display device, in particular, an IPS mode liquid crystal display device with improved contrast and improved color shift depending on the viewing angle direction during black display.

Means for solving the above-mentioned problems are as follows.
[1] Negative including stretching a film in a width direction perpendicular to the transport direction while contracting in the transport direction while transporting a film composed of one or more layers containing a material having a negative intrinsic birefringence value. A plate manufacturing method.
[2] The method according to [1], wherein the film is stretched in the width direction while being gripped and conveyed by a tenter clip and contracted by narrowing the interval between the tenter clips along the conveyance direction.
[3] The method according to [1] or [2], wherein the following mathematical formula (Z) is satisfied when the stretching ratio in the width direction is X% and the shrinkage ratio in the transport direction is Y%.

[4] The method according to any one of [1] to [3], wherein the material having a negative intrinsic birefringence value is a vinyl aromatic polymer.
[5] The method according to [4], wherein the vinyl aromatic polymer is a copolymer of styrene and / or a styrene derivative and maleic anhydride.
[6] The method according to any one of [1] to [3], wherein the material having a negative intrinsic birefringence is a polycarbonate having a fluorene skeleton.
[7] The method according to any one of [1] to [6], wherein a negative A plate having a width of 0.2 to 3 m and a length of 20 to 10,000 m is obtained.
[8] While transporting a film composed of one layer or two or more layers containing a material having a negative intrinsic birefringence value, the film is stretched in the width direction orthogonal to the transport direction, and contracted in the transport direction so as to be negative. The manufacturing method of a polarizing plate including the process made into A plate, and the lamination process which laminates | stacks this negative A plate and a polarizer in a elongate state.

[9] A negative A plate produced by any one of the methods [1] to [7].
[10] It has at least one layer containing a material having a negative intrinsic birefringence value, an in-plane slow axis is parallel to the longitudinal direction, and satisfies the following formulas (1) and (2): A long negative A plate:
Formula (1): 50 nm ≦ Re (550) ≦ 300 nm
Formula (2): -0.6 <= Rth (550) / Re (550) <=-0.4.
[11] Further, the negative A plate according to [10], wherein the following formula (3) is satisfied:
Formula (3): −0.55 ≦ Rth (550) / Re (550) ≦ −0.45.
[12] The negative A plate according to [10] or [11], further comprising a transparent polymer layer.
[13] The negative A plate of any one of [10] to [12], which is cut to a size that can be incorporated into a liquid crystal display device.
[14] A polarizing plate having at least the negative A plate of any one of [10] to [13] and a polarizer.

[15] The polarizing plate according to [14], wherein only a substantially isotropic adhesive layer and / or a substantially isotropic protective film is included between the negative A plate and the polarizer. .
[16] A pair of first and second polarizers arranged with their absorption axes orthogonal to each other, a pair of substrates, and liquid crystal molecules sandwiched between the pair of substrates with respect to the substrate during black display A liquid crystal display device comprising: a liquid crystal cell having a liquid crystal layer aligned substantially in parallel; and the negative A plate of [13] between the first polarizer and the liquid crystal cell,
A liquid crystal display device, wherein a slow axis of the negative A plate and a major axis direction of liquid crystal molecules during black display of the liquid crystal layer are substantially parallel or orthogonal.
[17] Only the isotropic adhesive layer and / or the substantially isotropic protective film is included between the second polarizer and the liquid crystal cell. ] Liquid crystal display device.
[18] A pair of first and second polarizers arranged with their absorption axes orthogonal to each other, a pair of substrates, and liquid crystal molecules held between the pair of substrates with respect to the substrate during black display A liquid crystal display device comprising: a liquid crystal cell having a liquid crystal layer aligned substantially vertically; and the negative A plate of [13] between the first polarizer and the liquid crystal cell.

ADVANTAGE OF THE INVENTION According to this invention, the novel method which can manufacture a negative A plate with high productivity can be provided.
In addition, according to the present invention, the productivity is high, and the liquid crystal cell is optically compensated accurately, which can contribute to improving the contrast and reducing the color shift depending on the viewing angle direction during black display. An A plate and a polarizing plate can be provided.
Further, according to the present invention, it is possible to provide a liquid crystal display device, in particular, an IPS mode liquid crystal display device with improved contrast and improved color shift depending on the viewing angle direction during black display.

  Hereinafter, the present invention will be described in detail. In the present specification, a numerical range represented by using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.

  In the present specification, “45 °”, “parallel” or “orthogonal” means that the angle is within a range of strictly less than ± 5 °. The error from the exact angle is preferably less than 4 °, more preferably less than 3 °. Regarding the angle, “+” means the clockwise direction, and “−” means the counterclockwise direction. Further, the “slow axis” means a direction in which the refractive index is maximized. The “visible light region” means 380 to 780 nm. Further, the measurement wavelength of the refractive index is a value at λ = 550 nm in the visible light region unless otherwise specified.

  Further, in this specification, the “polarizing plate” is cut into a size to be incorporated into a long polarizing plate and a liquid crystal device unless otherwise specified (in this specification, “cutting” includes “punching” and The term “includes“ cutout ”and the like” is used to include both polarizing plates. In this specification, “polarizing film” and “polarizing plate” are distinguished from each other. “Polarizing plate” means a laminate having a transparent protective film for protecting the polarizing film on at least one side of the “polarizing film”. It shall be.

In this specification, Re (λ) and Rth (λ) represent in-plane retardation and retardation in the thickness direction at the wavelength λ, respectively. Re (λ) is measured by making light having a wavelength of λ nm incident in the normal direction of the film in KOBRA 21ADH or WR (manufactured by Oji Scientific Instruments).
When the film to be measured is represented by a uniaxial or biaxial refractive index ellipsoid, Rth (λ) is calculated by the following method. In selecting the measurement wavelength λnm, the wavelength selection filter can be exchanged manually, or the measurement value can be converted by a program or the like.
Rth (λ) is Re (λ), with the in-plane slow axis (determined by KOBRA 21ADH or WR) as the tilt axis (rotation axis) (if there is no slow axis, any in-plane film The light of wavelength λ nm is incident from each of the inclined directions in steps of 10 degrees from the normal direction to 50 degrees on one side with respect to the film normal direction (with the direction of the rotation axis as the rotation axis). KOBRA 21ADH or WR is calculated based on the measured retardation value, the assumed value of the average refractive index, and the input film thickness value.
In the above case, in the case of a film having a direction in which the retardation value is zero at a certain tilt angle with the in-plane slow axis from the normal direction as the rotation axis, retardation at a tilt angle larger than the tilt angle. The value is changed to KOBRA 21ADH or WR after changing its sign to negative.
The retardation value is measured from two inclined directions with the slow axis as the tilt axis (rotation axis) (if there is no slow axis, the arbitrary direction in the film plane is the rotation axis). Based on the value, the assumed value of the average refractive index, and the input film thickness value, Rth can also be calculated from the following formulas (I) and (II).

式中、Ｒｅ（θ）は法線方向から角度θ傾斜した方向におけるレターデーション値をあらわす。
また、ｎｘは、面内における遅相軸方向の屈折率を表し、ｎｙは面内においてｎｘに直交する方向の屈折率を表し、ｎｚはｎｘ及びｎｙに直交する方向の屈折率を表し、ｄは膜厚を表す。

In the formula, Re (θ) represents a retardation value in a direction inclined by an angle θ from the normal direction.
Further, nx represents the refractive index in the slow axis direction in the plane, ny represents the refractive index in the direction orthogonal to nx in the plane, nz represents the refractive index in the direction orthogonal to nx and ny, and d Represents the film thickness.

When the film to be measured is a film that cannot be expressed by a uniaxial or biaxial refractive index ellipsoid, that is, a film without a so-called optical axis, Rth (λ) is calculated by the following method.
Rth (λ) is the above-mentioned Re (λ), and the in-plane slow axis (determined by KOBRA 21ADH or WR) is the tilt axis (rotary axis), and −50 degrees to +50 degrees with respect to the film normal direction. Measured at 11 points by making light of wavelength λ nm incident from each tilted direction in 10 degree steps, and based on the measured retardation value, assumed value of average refractive index, and input film thickness value KOBRA 21ADH or WR is calculated.
In the above measurement, as the assumed value of the average refractive index, the values in the polymer handbook (John Wiley & Sons, Inc.) and catalogs of various optical compensation films can be used.
Moreover, about the thing whose average refractive index value is not known, it can measure with an Abbe refractometer. Examples of the average refractive index values of main optical compensation films are as follows:
Cellulose acylate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49), and polystyrene (1.59).
The KOBRA 21ADH or WR calculates nx, ny, and nz by inputting the assumed average refractive index and the film thickness. Nz = (nx−nz) / (nx−ny) is further calculated from the calculated nx, ny, and nz.

[Method for producing negative A plate]
The present invention relates to a method for manufacturing a negative A plate. The negative A plate generally refers to a retardation film having an in-plane slow axis and a property that Rth / Re at a wavelength of 550 nm is about −0.5. In the present invention, the “negative A plate” does not necessarily require that Rth / Re be −0.5, Re is 50 nm or more, and Rth / Re is −0.60−−. All of 0.40 shall be included.

The method for producing a negative A plate of the present invention, while transporting a film composed of one or more layers containing a material having a negative intrinsic birefringence value, stretches in the width direction perpendicular to the transport direction, and It is characterized by contracting in the transport direction.
The production method of the present invention can be carried out using, for example, a tenter that operates in the biaxial direction of the film conveyance direction and the width direction perpendicular thereto, such as a chain type, a screw type, a pantograph type, and a linear motor type. . The film is transported in the transport direction by gradually narrowing the distance between the clips while stretching the film in the width direction while gripping and transporting the lateral end of the film with the clip of the tenter. Can be shrunk.

  While stretching the width direction of the film as described above, as a stretching apparatus capable of concretely carrying out a stretching step that increases the film thickness by shrinking the width direction of the film, a FITZ machine manufactured by Ichikin Kogyo Co., Ltd. is desirable. Can be used. This apparatus is described in Japanese Patent Laid-Open No. 2001-38802.

  In the method using the tenter that operates in the biaxial direction of the film conveyance direction and the width direction described above, at least a part of the stretching step and the shrinking step are performed simultaneously. As a result of the inventors' research, when the stretching process and the shrinking process are carried out at the same time, stretching in the film plane called bowing is performed by adjusting the timing, magnification, and speed of stretching / shrinking. -It has been found that it has the advantage of easily reducing non-uniform shrinkage.

  Further, as a result of intensive studies by the present inventors, Rth / Re at a wavelength of 550 nm is about −0. 0 while exhibiting in-plane retardation (for example, Re (550) of 50 to 200 nm) as a negative A plate. 5 (for example, −0.6 to −0.4), the relationship between the stretching ratio X% in the width direction and the shrinkage ratio Y% in the transport direction is expressed by the following formula (Z). It was found that satisfying this is effective.

  Even if the relationship between the stretching ratio and the shrinkage ratio is below the lower limit of the formula (Z), a negative A plate can be produced, but a special additive is added to the film. Or a technique of blending different polymers is required, which causes other problems such as crying of the additive from the film and an increase in manufacturing cost during the above-mentioned processing. On the other hand, similarly, even when the relationship between the stretching ratio and the shrinkage ratio exceeds the upper limit of the mathematical formula (Z), it is possible to produce a negative A plate. May occur and may not be suitable for use as a retardation film or the like.

  In the range satisfying the above formula (Z), the stretching ratio is preferably 5 to 100%, more preferably 10 to 80%. Moreover, as a shrinkage rate, 3 to 30% is preferable and 5 to 20% is more preferable.

In addition, the stretch rate as used in the field of this invention means the ratio of the length of the film after extending | stretching with respect to the length of the film before extending | stretching in a extending direction, and a shrinkage rate is the film before shrinking | contracting in a shrinking direction. It means the ratio of the contracted length of the film after contraction to the length.
In the production method of the present invention, the onset of shrinkage means the time when the film dimension starts to substantially decrease, and the decrease in the film dimension is caused by, for example, application of a physical external force to the film or heat shrinkage. This includes the case where physical external force is not applied to the film. By the end of the shrinking process is meant when the reduction of the film dimensions is substantially completed.
Similarly, the beginning of the stretching process means that the film dimension starts to increase substantially. The increase in the film dimension is, for example, applying a force to the film to physically stretch the film. Is due to. The end of the stretching process means a time when the application of force to the film is stopped and the stretching process is physically terminated.

The stretching and shrinking may be performed under heating. It is preferable to carry out at Tg-30 degreeC-Tg + 50 degreeC with respect to the glass transition temperature Tg of the film at the time of a process, and it is more preferable that it is Tg-10 degreeC-Tg + 20 degreeC. Heating is preferably performed with a heat roll, a radiant heat source (such as an IR heater), or warm air.
The glass transition temperature can be measured by “DSC2920 Modulated DSC” manufactured by TA Instruments. The glass transition temperature was measured not after film formation but after resin polymerization in the form of flakes or chips.

  In the production method of the present invention, the stretching / shrinking of the film may be performed in one stage or in multiple stages. When performing in multiple stages, it is preferable that the draw ratio and shrinkage rate in each step satisfy the above relationship.

  In the production method of the present invention, the film conveyance speed is not particularly limited. The conveying speed is preferably set so that the stretching speed is preferably 5 to 1,000% / min, more preferably 10 to 500% / min.

  According to the production method of the present invention, a negative A plate having an in-plane slow axis in the longitudinal direction can be continuously produced in a long shape. Examples of the long form include a shape having a width of about 0.2 to 3 m and a length of about 20 to 10,000 m.

  The film used in the production method of the present invention may be produced by any film production method such as a melt film production method substantially free of a solvent and a solution casting method containing a solvent. When the film is a multilayer film, it can be produced using a melt coextrusion method or a co-casting method. After the film forming step, the stretching / shrinking treatment may be performed continuously. For example, when a film formed by the solution casting method is used, the above stretching / shrinking treatment may be performed as an alternative to the wet stretching performed during the drying process of the solution casting method. Moreover, you may perform the said extending | stretching / shrinkage | contraction process continuously to the film formed by the melt extrusion method, or the film after drying produced by the solution casting method. Of course, the above-described stretching / shrinking treatment can be carried out separately after being wound into a roll or the like.

In the production method of the present invention, a film having a layer composed of one layer or two or more layers including a material having a negative intrinsic birefringence value is used.
The intrinsic birefringence value Δn ⁰ of the material is a value calculated by the equation [1].
Δn ⁰ = (2π / 9) (Nd / M) {(n _a +2) ² / n _a } (α ₁ −α ₂ ) ... [1]
Where π is the circumference, N is the Avogadro number, d is the density, M is the molecular weight, n _a is the average refractive index, α ₁ is the polarizability of the polymer in the molecular chain axis direction, and α ₂ is the polymer molecular chain. The polarizability in the direction perpendicular to the axis.
The material having a negative intrinsic birefringence value is preferably a polymer material, and the film includes a negative intrinsic birefringence polymer material as a main component (which means that the solid content is 50% by mass or more). Or it consists of two or more layers.

  Examples of the polymer having a negative intrinsic birefringence value include vinyl aromatic polymers. Examples of the vinyl aromatic polymer include polystyrene, styrene, α-methylstyrene, o-methylstyrene, p-methylstyrene, p-chlorostyrene, p-nitrostyrene, p-aminostyrene, and p-carboxy. Vinyl aromatic monomers such as styrene and p-phenylstyrene, ethylene, propylene, butadiene, isoprene, (meth) acrylonitrile, α-chloroacrylonitrile, methyl (meth) acrylate, ethyl (meth) acrylate, (meth ) Copolymers with other monomers such as acrylic acid, maleic anhydride and vinyl acetate. Among these, polystyrene or a copolymer of styrene and maleic anhydride is preferable. In addition, as long as the negative intrinsic birefringence is not impaired, other functions may be added by controlling physical properties such as glass transition temperature and photoelasticity as copolymerization with other monomers.

Other examples of the polymer having a negative intrinsic birefringence value include polycarbonate having a fluorene skeleton. Since the fluorene skeleton is oriented perpendicular to the polymer main chain by a stretching operation or the like, it exhibits a large negative polarizability.
Preferable examples of the polycarbonate having a fluorene skeleton include a polymer containing a repeating unit represented by the following formula (I).

ここで、Ｒ¹〜Ｒ⁸は、互いに独立に、水素原子、ハロゲン原子、炭素数１〜６の炭化水素基及び炭素数１〜６の炭化水素−Ｏ−基よりなる群から選ばれる基であり、そしてＸは、下記式（１）−１：

Here, R ^{1 to} R ⁸ are each independently a group selected from the group consisting of a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 6 carbon atoms, and a hydrocarbon-O— group having 1 to 6 carbon atoms. And X is the following formula (1) -1:

で表わされる基であり、Ｒ³⁰及びＲ³¹は、互いに独立に、ハロゲン原子又は炭素数１〜３のアルキル基であり、そしてｎ及びｍは互いに独立に、０〜４の整数である。
上記式（Ｉ）で表される繰返し単位を全繰返し単位の５０〜９５モル％含有するものが好ましく、より好ましくは６０〜９５モル％、さらに好ましくは７０〜９０モル％である。

R ³⁰ and R ³¹ are each independently a halogen atom or an alkyl group having 1 to 3 carbon atoms, and n and m are each independently an integer of 0 to 4.
Those containing 50 to 95 mol% of the repeating units represented by the above formula (I) are preferred, more preferably 60 to 95 mol%, still more preferably 70 to 90 mol%.

  These polycarbonates having a fluorene skeleton exhibit a high glass transition temperature, and have excellent physical properties in terms of handling and stretch moldability.

  A more preferable example of the polycarbonate is a polymer containing a repeating unit represented by the above formula (I) and a repeating unit represented by the following formula (II).

上記式（ＩＩ）中、Ｒ⁹〜Ｒ¹⁶は、それぞれ独立に、水素原子、ハロゲン原子及び炭素数１〜２２の炭化水素基よりなる群から選ばれる少なくとも一種の基であり、Ｙは下記式群のそれぞれで表わされる基：

In the above formula (II), R ^{9 to} R ¹⁶ are each independently at least one group selected from the group consisting of a hydrogen atom, a halogen atom and a hydrocarbon group having 1 to 22 carbon atoms, and Y represents the following formula: Groups represented by each of the groups:

よりなる群から選ばれる少なくとも一種の基である。ここで、Ｙ中のＲ¹⁷〜Ｒ¹⁹、Ｒ²¹及びＲ²²は、それぞれ独立に、水素原子、ハロゲン原子、又はアルキル基、アリール基の如き炭素数１〜２２の炭化水素基であり、Ｒ²⁰及びＲ²³はアルキル基、アリール基の如き炭素数１〜２０の炭化水素基であり、また、Ａｒ¹〜Ａｒ³は、それぞれ独立に、フェニル基の如き炭素数６〜１０のアリール基である。

And at least one group selected from the group consisting of: Here, R ^{17 to} R ¹⁹ , R ²¹ and R ²² in Y are each independently a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 22 carbon atoms such as an alkyl group or an aryl group, and R ²⁰ and R ²³ are each a hydrocarbon group having 1 to 20 carbon atoms such as an alkyl group or an aryl group, and Ar ^{1 to} Ar ³ are each independently an aryl group having 6 to 10 carbon atoms such as a phenyl group. is there.

  The polymer containing the repeating units of the above formulas (I) and (II) preferably contains 50 to 95 mol% of the repeating units represented by the above formula (I) with respect to the total, more preferably 60 It is -95 mol%, More preferably, it is 70-90 mol%.

  The polycarbonate can be produced by a known method. Polycarbonate is suitably produced by a polycondensation method of a dihydroxy compound and phosgene, a melt polycondensation method, a solid phase polymerization method or the like.

  Other examples of the polymer having a negative intrinsic birefringence value that can be used in the present invention include a norbornene-based ring-opening (co) polymer represented by the following formula (III) and containing the structural unit (III). . In the present specification, “(co) polymer” means both a homopolymer and a copolymer. In the present specification, the “norbornene-based ring-opening (co) polymer” means any of (co) polymers obtained by polymerizing or copolymerizing norbornene-based compounds and compounds obtained by hydrogenating these compounds. is there.

In formula (III), m and n are each independently an integer of 0 to 2;
X is a group represented by the formula: —CH═CH— or a group represented by the formula: —CH ₂ CH ₂ —;
R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ and R ⁹ are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted carbon atom having 1 to 30 carbon atoms. Represents an atom or group selected from the group consisting of a hydrogen group (which may have a linking group containing an oxygen atom, a nitrogen atom, a sulfur atom or a silicon atom) and a polar group;
s, t, and u are each independently an integer of 0 to 3.

  The norbornene-based ring-opening (co) polymer may contain a structural unit (IV) represented by the following general formula (IV) as necessary.

In the formula (IV), X, R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , m, n, s and t have the same meanings as in the above formula (III), respectively. is there.
In the formula (IV), R ¹⁰ , R ¹¹ , R ¹² and R ¹³ are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted hydrocarbon group having 1 to 30 carbon atoms (however, an oxygen atom, a nitrogen atom) An atom, a sulfur atom or a linking group containing a silicon atom), and an atom or group selected from the group consisting of polar groups, A polycyclic group may be formed, and R ¹⁰ and R ¹¹ , or R ¹² and R ¹³ may be integrated to form a divalent hydrocarbon group.

Here, as a halogen atom, a fluorine atom, a chlorine atom, and a bromine atom are mentioned.
Examples of the hydrocarbon group having 1 to 30 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 and allyl group; Groups, alkylidene groups such as propylidene groups; aromatic groups such as phenyl groups, naphthyl groups, anthracenyl groups, and the like. These hydrocarbon groups may be substituted, and examples of the substituent include halogen atoms such as fluorine, chlorine and bromine, phenylsulfonyl group and cyano group.

Further, the substituted or unsubstituted hydrocarbon group may be directly bonded to the ring structure or may be bonded via a linking group. Examples of the linking group include a divalent hydrocarbon group having 1 to 10 carbon atoms (for example, — (CH ₂ ) _q —, q is an alkylene group represented by an integer of 1 to 10); an oxygen atom, a nitrogen atom, A linking group containing a sulfur atom or a silicon atom (for example, a carbonyl group (—CO—), a carbonyloxy group (—COO—), a sulfonyl group (—SO ₂ —), a sulfonyl ester group (—SO ₂ —O—), Ether bond (—O—), thioether bond (—S—), imino group (—NH—), amide bond (—NHCO—), siloxane bond (—Si (R ₂ ) O— (where R is methyl And alkyl groups such as ethyl))); or a combination of two or more of these groups.

  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, an imide group, a triorganosiloxy group, a triorganosilyl group, Examples thereof include 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, Biphenylyloxycarbonyl group and the like; examples of the triorganosiloxy group include trimethylsiloxy group and triethylsiloxy group; examples of the triorganosilyl group include trimethylsilyl group and triethylsilyl group. Group and the like; examples of the amino group include primary amino groups such as, alkoxysilyl The group for example a trimethoxysilyl group, triethoxysilyl group, and the like.

In the formula (III), four R ⁸ and R ⁹ are each an independent atom or group.
In the formula (IV), R ¹⁰ , R ¹¹ , R ¹² , and R ¹³ may be bonded to each other to form a monocyclic or polycyclic group that may have a hetero atom as described above. Alternatively, R ¹⁰ and R ¹¹ , or R ¹² and R ¹³ may be integrated to form a divalent hydrocarbon group. However, the structural unit (IV) represented by the general formula (IV) does not include the structural unit (III) represented by the general formula (III).

In the formula (IV), when R ¹⁰ , R ¹¹ , R ¹² and R ¹³ are bonded to each other to form a monocyclic or polycyclic group which may have a hetero atom, The polycycle may be an aromatic ring or a non-aromatic ring. In the formula (IV), examples in which R ¹⁰ , R ¹¹ , R ¹² and R ¹³ are bonded to each other to form a ring structure are partially shown below.

  Specific examples of the structural unit (III) constituting the norbornene-based ring-opening (co) polymer and optionally the structural unit (IV) include, for example, a monomer (IIIm) and a monomer described later And structural units derived from (IVm).

  The norbornene-based ring-opening (co) polymer contains the structural unit (III) represented by the general formula (III) in a total amount of usually 2 mol% or more, preferably 5 mol% or more. desirable.

  When the norbornene-based ring-opening copolymer has the structural unit (III) represented by the general formula (III) and the structural unit (IV) represented by the general formula (IV) The proportion of the structural unit (IV) is preferably 98 mol% or less in all the structural units. In the norbornene-based ring-opening (co) polymer, the ratio of the structural unit (III) to the structural unit (IV) is usually a molar ratio of structural unit (III) / structural unit (IV) and is usually 100/0. ˜2 / 98, preferably 100/0 to 5/95, more preferably 100/0 to 10/90.

  The norbornene-based ring-opening (co) polymer may have another structural unit in addition to the structural unit (III) and the structural unit (IV). Such a norbornene-based ring-opening (co) polymer has the structural unit (III) and the structural unit (IV) in total, preferably 10 mol% or more, more preferably 15 mol% in all the structural units. It is desirable to have the above.

  As the structural unit other than the structural unit (III) and the structural unit (IV) that the norbornene-based ring-opening (co) polymer may have, a monomer (IIIm) to be described later for deriving the structural unit (III) is used. And a structural unit derived from a copolymerizable monomer together with a monomer (IVm) to be described later which derives the structural unit (IV). Specifically, for example, cyclic olefins such as cyclobutene, cyclopentene, cyclooctene and cyclododecene; non-conjugated cyclic polyenes such as 1,4-cyclooctadiene, dicyclopentadiene and cyclododecatriene; polybutadiene, polyisoprene, polyisoprene, Structural units derived from low polymers having double bonds such as styrene-butadiene, ethylene-nonconjugated diene polymers, and ring-opening (co) polymers of norbornene monomers; It is done.

In the norbornene-based ring-opening (co) polymer, 90 mol% or more, preferably 95 mol% or more, more preferably 97 mol% or more of the total of X in the structural unit (III) and the structural unit (IV) is − A group represented by CH ₂ CH ₂ — is preferable. That is, the norbornene-based ring-opening (co) polymer is preferably a (co) polymer that is sufficiently hydrogenated and has few double bonds in the main chain. The norbornene-based ring-opening (co) polymer has a more stable (co) weight as the ratio of X in the general formula is a group represented by —CH ₂ CH ₂ —, that is, as the hydrogenation ratio increases. It is preferable because it becomes a coalescence and coloration and deterioration due to heat are suppressed.

  The norbornene-based ring-opening (co) polymer is represented by a norbornene-based monomer (IIIm) represented by the following general formula (IIIm) alone or, if necessary, the following general formula (IVm) The norbornene-based ring-opening (co) polymer can be produced by ring-opening (co) polymerization with the norbornene-based monomer (IVm).

In formula (IIIm), m and n are each independently an integer of 0 to 2;
R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , and R ⁹ are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted carbon atom having 1 to 30 carbon atoms. Represents an atom or group selected from the group consisting of a hydrocarbon group (which may have a linking group containing an oxygen atom, a nitrogen atom, a sulfur atom or a silicon atom) and a polar group;
s, t, and u are each independently an integer of 0 to 3.

In formula (IVm), m and n are each independently an integer of 0 to 2;
R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ and R ⁷ are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted hydrocarbon group having 1 to 30 carbon atoms (oxygen atom, A nitrogen atom, a sulfur atom or a linking group containing a silicon atom), and an atom or group selected from the group consisting of polar groups;
R ¹⁰ , R ¹¹ , R ¹² and R ¹³ are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted hydrocarbon group having 1 to 30 carbon atoms (however, an oxygen atom, a nitrogen atom, a sulfur atom or silicon Represents an atom or group selected from the group consisting of a polar group, and may be bonded to each other to form a monocyclic or polycyclic group that may have a hetero atom R ¹⁰ and R ¹¹ , or R ¹² and R ¹³ may be integrated to form a divalent hydrocarbon group;
s and t are each independently an integer of 0 to 3.
In the norbornene monomer (IIIm), m, n, X, R ^{1 to} R ⁹ , s, t, and u have the same meanings as those in the structural unit (III). In the monomer (IVm), m, n, X, R ^{1 to} R ⁷ , R ^{10 to} R ¹³ , s and t have the same meanings as those in the structural unit (IV).

  In the norbornene-based monomer (IIIm), there are exo and endo isomers as the stereoisomers at the site where the spiroaromatic structure and the cyclo ring structure are linked, but these compositions are not particularly limited. None can be selected according to the desired characteristics.

  The material having a negative intrinsic birefringence value may contain two or more of the polymers exemplified above, or may contain other polymers. When blending polymers, compatible blends are preferred to maintain transparency, but even if they are not completely compatible, if the refractive index between the components is matched, light scattering between components is suppressed and transparency is improved. It is possible to make it.

The film may be a multilayer structure having two or more layers including a material having a negative intrinsic birefringence value. Furthermore, the film may have a layer including a layer made of another material together with a layer containing a material having a negative intrinsic birefringence value. The other layer is preferably laminated on at least one side of the layer containing a material having a negative intrinsic birefringence value, and it is particularly preferred that a transparent resin layer is laminated on both sides of the layer. By laminating a transparent resin layer on a layer containing a material having a negative intrinsic birefringence value, the layer containing a material having a negative intrinsic birefringence value can be prevented from being broken, and wavelength dispersion can be easily achieved as a laminate. It becomes possible to control. In this case, the transparent resin layer is preferably substantially non-oriented from the viewpoint of efficiently using the phase difference of the layer containing a material having a negative intrinsic birefringence value. The transparent resin layer is not particularly limited as long as it has a thickness of 1 mm and a total light transmittance of 80% or more. For example, a polymer having an alicyclic structure, a chain olefin polymer such as polyethylene or polypropylene Polycarbonate polymer, polyester polymer, polysulfone polymer, polyethersulfone polymer, polystyrene polymer, polyvinyl alcohol polymer, polymethacrylate polymer, and the like. Among these, a polymer having an alicyclic structure or a chain olefin polymer is preferable, and a polymer having an alicyclic structure is preferable from the viewpoint of transparency, low hygroscopicity, dimensional stability, lightness, and the like. Particularly preferred.
Examples of the polymer having an alicyclic structure include those having an alicyclic structure in the main chain and / or side chain. Among these, from the viewpoints of mechanical strength, heat resistance, etc., a polymer having an alicyclic structure in the main chain can be particularly preferably used.
Examples of the alicyclic structure of the polymer include a saturated cyclic hydrocarbon (cycloalkane) structure and an unsaturated cyclic hydrocarbon (cycloalkene) structure. From the viewpoint of mechanical strength and heat resistance, A cycloalkene structure is preferred, and a cycloalkane structure is most preferred. The number of carbon atoms constituting the alicyclic structure is not particularly limited, but is usually 4 to 30, preferably 5 to 20, more preferably 5 to 15 in the mechanical strength, The properties of heat resistance and film formability are highly balanced and suitable. The ratio of the repeating unit containing the alicyclic structure in the alicyclic structure-containing polymer used in the present invention may be appropriately selected according to the purpose of use, but is preferably 50% by mass or more, More preferably, it is 70 mass% or more, Most preferably, it is 90 mass% or more. When the ratio of the repeating unit containing the alicyclic structure in the alicyclic structure-containing polymer is within this range, it is preferable from the viewpoint of transparency and heat resistance of the film.
Examples of the polymer having an alicyclic structure include a ring-opening polymer or a ring-opening copolymer of a norbornene monomer or a hydrogenated product thereof; an addition polymer or an addition copolymer of a norbornene monomer Or a hydrogenated product thereof; a polymer of a monocyclic cycloolefin monomer or a hydrogenated product thereof; a polymer of a cyclic conjugated diene monomer or a hydrogenated product thereof; a vinyl alicyclic hydrocarbon monomer A polymer or copolymer of a polymer or a hydrogenated product thereof; a polymer or copolymer of a vinyl aromatic hydrocarbon monomer or a hydrogenated product of an unsaturated bond containing an aromatic ring thereof; Can do.
The polymer having an alicyclic structure is selected from known polymers disclosed in, for example, JP-A-2002-321302.
In addition, for transparent resins, antioxidants, heat stabilizers, light stabilizers, UV absorbers, antistatic agents, dispersants, chlorine scavengers, flame retardants, crystallization nucleating agents, and antiblocking agents are used as necessary. Agents, antifogging agents, release agents, pigments, organic or inorganic fillers, neutralizing agents, lubricants, decomposing agents, metal deactivators, antifouling agents, antibacterial agents and other resins, thermoplastic elastomers, etc. Known additives can be added as long as the effects of the invention are not impaired.

  Moreover, when using a polymer as a raw material of the film, it is preferable to use a polymer having a water content of 1.0% or less. Use of such a polymer is preferable because the influence of temperature and humidity (particularly humidity) on the optical characteristics of the negative A plate obtained can be reduced.

In order to produce a negative A plate by the production method of the present invention, the film before stretching / shrinking treatment preferably satisfies the following formulas (5) and (6).
(5): −20 nm ≦ Re (550) ≦ 20 nm
(6): −20 nm ≦ Rth (550) ≦ 20 nm

The film having the above optical characteristics can be easily produced by the above-described exemplified extrusion molding method and solution casting method. In addition, in order to obtain a film that satisfies the above formula, a film subjected to stretching treatment may be used for production of a negative A plate. It is preferable to perform a pre-heat treatment step in which preheating is performed before the stretching step, since optical characteristics that satisfy the above formulas (5) and (6) are easily expressed. In this pre-heat treatment process, it is preferable to heat to Tg + (25-100) degreeC with respect to the glass transition point temperature Tg of the film before extending | stretching. The heat treatment time is preferably about 1 second to 3 minutes.
Moreover, you may perform the post-heat treatment process which heat-processes the obtained film after an extending process. The post-heat treatment temperature is preferably performed at a temperature of Tg−20 ° C. to Tg + 10 ° C. with respect to the glass transition temperature Tg of the obtained film. The post heat treatment time is preferably 1 second to 3 minutes.
Further, the heating method in these pre- and post-heat treatment steps may be zone heating or partial heating using an infrared heater.

  Moreover, you may slit the both ends of a film in the middle of the manufacturing process of the film used as the said raw material, or the last. These slit scraps are preferably recovered and reused as raw materials.

Hereinafter, various techniques that can be used when producing a film as a raw material by the solution casting method and the melt film forming method will be described.
-Production of film by solution casting method A tenter is disclosed in Japanese Patent Application Laid-Open No. 11-077718. When a web is dried while maintaining a width with a tenter, a dry gas blowing method, a blowing angle, a wind speed distribution, a wind speed Air flow, temperature difference, air flow difference, upper and lower blown air flow ratio, use of high specific heat drying gas, etc. are controlled appropriately to increase the speed by the solution casting method, flatness when expanding the web width, etc. A technique for ensuring the prevention of quality degradation is disclosed.

  Japanese Patent Application Laid-Open No. 11-077782 describes an invention in which a stretched thermoplastic resin film is heat treated by providing a temperature gradient in the width direction of the film in the thermal relaxation process after the stretching process in order to prevent unevenness. Yes.

  Furthermore, in order to prevent the occurrence of unevenness, Japanese Patent Application Laid-Open No. 4-204503 describes an invention in which the film is stretched with the solvent content of 2 to 10% based on the solid content.

  Further, in order to suppress curling due to the regulation of the clip biting width, Japanese Patent Application Laid-Open No. 2002-248680 discloses stretching with a tenter clip biting width D ≦ (33 / (log stretch rate × log volatile content)). Describes an invention that suppresses curling and facilitates film conveyance after the stretching step.

  Furthermore, in order to achieve both high-speed soft film conveyance and stretching, Japanese Patent Application Laid-Open No. 2002-337224 describes an invention in which tenter conveyance is switched between a first half pin and a second half clip.

  Japanese Patent Application Laid-Open No. 2002-187960 discloses that a polymer dope solution is cast on a casting support for the purpose of easily improving the viewing angle characteristics and improving the viewing angle. The web (film) peeled from the support for stretching is stretched 1.0 to 4.0 times in at least one direction while the amount of residual solvent in the web is 100% by mass or less, particularly 10 to 100% by mass. An optically biaxial invention obtained by doing so is described. As a more preferred embodiment, it is described that the film is stretched 1.0 to 4.0 times in at least one direction while the amount of residual solvent in the web is in the range of 100% by mass or less, particularly 10 to 100% by mass. .

Furthermore, in order to produce a retardation film having little additive bleed-out, no delamination phenomenon between layers, good slipperiness and excellent transparency, it is described in JP-A-2003-014933. In addition, a dope A containing a resin, an additive and an organic solvent, and a dope B containing no additive or a resin having a lower additive content than the dope A, an additive and an organic solvent are prepared. The co-cast on the support so that the dope A is the core layer and the dope B is the surface layer, the organic solvent is evaporated until it can be peeled, and then the web is peeled off from the support and further stretched. The invention describes that the residual solvent in the resin film is stretched 1.1 to 1.3 times in at least one axial direction in the range of 3 to 50% by mass.
Furthermore, as a preferred embodiment, the web is peeled from the support, and further, the dope containing a resin and an organic solvent is stretched 1.1 to 3.0 times in a uniaxial direction at a stretching temperature of 140 to 200 ° C. A dope B containing A, resin, fine particles and an organic solvent is prepared, and the dope A is co-cast on the support so that the dope A becomes a core layer and the dope B becomes a surface layer, and the organic solvent is made peelable. After evaporating the web, the web is peeled from the support and further stretched 1.1 to 3.0 times in the uniaxial direction in the range of 3 to 50% by mass of the residual solvent in the resin film during stretching. Further, the film is stretched 1.1 to 3.0 times in at least one axial direction at a stretching temperature in the range of 140 to 200 ° C., dope A containing a resin, an organic solvent and an additive, and no additive or additive. Resin, additive and presence of less than dope A A dope B containing a solvent, a dope C containing a resin, fine particles, and an organic solvent are prepared so that the dope A becomes a core layer, the dope B becomes a surface layer, and the dope C becomes a surface layer opposite to the dope B. The organic solvent is evaporated until it can be peeled off, the web is peeled off from the support, and the amount of residual solvent in the resin film during stretching is 3 to 50% by mass. Stretching at least uniaxially in a range of 1.1 to 3.0 times, stretching at a stretching temperature of 140 to 200 ° C. at least uniaxially in a direction of 1.1 to 3.0 times, The additive amount is 1 to 30% by mass with respect to the resin, the additive amount in the dope B is 0 to 5% by mass with respect to the resin, and the additive is a plasticizer, an ultraviolet absorber, or a retardation preparation agent. The organic solvent in dope A and dope B is Renkuroraido, or methyl acetate with respect to the total organic solvents can be utilized to contain more than 50 wt% are described.

  Furthermore, in order to prevent foaming of the tenter-dried web, improve detachability, and prevent dust generation, Japanese Patent Application Laid-Open No. 2003-004374 discloses that the hot air from the dryer is applied to both edges of the web. The invention is described in which the width of the dryer is formed shorter than the width of the web so as not to hit.

  Further, in order to prevent foaming of the tenter-dried web, improve releasability, and prevent dust generation, Japanese Patent Application Laid-Open No. 2003-019775 discloses that both ends of the web are prevented from hitting the holding portion of the tenter. An invention is described in which a wind shield is provided on the inside of the part.

  Furthermore, in order to stably carry and dry, JP-A-2003-053749 discloses that the thickness after drying of both ends of the film supported by the pin tenter is X μm, the average after drying of the product part of the film When the thickness is T μm, the relationship between X and T is 40 + X ≦ 200 when Formula (1) T ≦ 60, and 40+ (T−60) × when Formula (2) 60 <T ≦ 120. An invention that satisfies the relationship of 52+ (T−120) × 0.2 ≦ X ≦ 400 when 0.2 ≦ X ≦ 300 or Formula (3) 120 <T is described.

  Further, in order to prevent wrinkles from occurring in the multistage tenter, JP-A-2-182654 discloses a tenter device in which a heating chamber and a cooling chamber are provided in a dryer of the multistage tenter, and left and right clip chains are provided. A separate cooling invention is described.

  Furthermore, in order to prevent web breakage, wrinkles, and conveyance failure, Japanese Patent Application Laid-Open No. 9-077315 describes an invention in which the inner pin density is increased and the outer pin density is decreased in the pin tenter pin. Yes.

  In addition, in order to prevent foaming of the web itself and adhesion of the web to the holding means in the tenter, Japanese Patent Application Laid-Open No. 9-085846 discloses that both side edge holding pins of the web are blown-type cooled in the tenter drying apparatus. An invention is described in which a pin is cooled to below the foaming temperature of the web and the pin immediately before the web is entrapped is cooled to a gelation temperature of the dope in the duct type cooler + 15 ° C. or lower.

  Further, in order to prevent pin tenter losing and improve foreign matter, Japanese Patent Application Laid-Open No. 2003-103542 discloses a web surface that cools the insertion structure and contacts the insertion structure in the pin tenter. An invention relating to a solution casting method in which the temperature does not exceed the gelling temperature of the web is described.

In order to prevent deterioration in quality such as flatness when the speed is increased by the solution casting method or the width of the web is widened by a tenter, JP-A-11-0777718 discloses a web in the tenter. Is dried, the wind speed is 0.5-20 (40) m / s, the transverse temperature distribution is 10% or less, the web up-down air volume ratio is 0.2-1 and the dry gas ratio is 30-250 J /. The invention of Kmol is described.
Furthermore, preferable drying conditions are disclosed depending on the amount of residual solvent in drying in the tenter.
Specifically, after the web is peeled off from the support, the angle of the air blown from the air outlet is in the range of 30 to 150 ° with respect to the film plane until the amount of residual solvent in the web reaches 4% by mass. And when the wind speed distribution on the film surface located in the direction in which the drying gas is blown out is based on the upper limit value of the wind speed, the difference between the upper limit value and the lower limit value is within 20% of the upper limit value. When blowing, drying the web, and when the residual solvent amount in the web is 130% by mass or less and 70% by mass or more, the wind speed on the web surface of the dry gas blown from the blow type dryer is 0.5 m / sec or more. When the residual solvent amount is less than 70% by mass and 4% by mass or more when the residual solvent amount is less than 70% by mass, the drying gas is blown by the dry gas wind blown at a wind speed of 0.5m / sec to 40m / sec. When the temperature distribution of the drying gas in the width direction of the web is based on the upper limit value of the gas temperature, the difference between the upper limit value and the lower limit value should be within 10% of the upper limit value, the amount of residual solvent in the web Is 4 mass% or more and 200 mass% or less, it is described that the air volume ratio q of the dry gas blown out from the blow-out port of the blow-type dryer located above and below the conveyed web is 0.2 ≦ q ≦ 1. ing.
Furthermore, as a preferred embodiment, at least one kind of gas is used for the drying gas, the average specific heat is 31.0 J / K · mol or more and 250 J / K · mol or less, and the room temperature contained in the drying gas during drying. And the concentration of the liquid organic compound is dried with a drying gas having a saturated vapor pressure of 50% or less.

In order to prevent deterioration of flatness and coating due to the generation of contaminants, Japanese Patent Application Laid-Open No. 11-0777719 discloses a TAC (triacetyl cellulose) manufacturing apparatus in which a tenter clip incorporates a heating portion. The invention is described.
As a more preferable aspect, a device for removing foreign matter generated at the contact portion between the clip and the web between the time when the tenter clip releases the web and the time when the web is carried again, a jetting gas or liquid, and The removal of foreign matter using a brush, the residual amount at the time of contact between the clip or pin and the web is 12% by mass or more and 50% by mass or less, and the surface temperature of the contact part between the clip or pin and the web is 60%. It is disclosed that the temperature is not lower than 200 ° C. and lower than 200 ° C. (more preferably, not lower than 80 ° C. and not higher than 120 ° C.)

  In order to improve flatness, improve quality deterioration due to tearing in the tenter, and increase productivity, Japanese Patent Application Laid-Open No. 11-090943 discloses an arbitrary transport length Lt (m) of the tenter. The ratio Lr = Ltt / Lt of the total length Ltt (m) in the conveying direction of the portion where the clip of the tenter having the same length as Lt holds the web is 1.0 ≦ Lr ≦ 1.99 The invention is described. Furthermore, as a preferable aspect, it is disclosed that the portion for holding the web is arranged without a gap when viewed from the web width direction.

In addition, when introducing a web into a tenter, in order to improve flatness deterioration and instability due to web sagging, Japanese Patent Application Laid-Open No. 11-090944 discloses a plastic film manufacturing apparatus in front of a tenter entrance. Describes an invention having a sag suppressing device in the web width direction.
Further, as a more preferable aspect, the sag suppressing device is a rotating roller that rotates in the direction range of 2 to 60 ° in the width direction, has an air intake device on the top of the web, and can blow air from under the web. Having a blower is also disclosed.

  In order to prevent deterioration of quality and sagging that hinders productivity, Japanese Patent Application Laid-Open No. 11-090945 discloses that a web peeled from a support has an angle with respect to the horizontal in the TAC manufacturing method. The invention to be introduced into the tenter is described.

  In order to make a film having stable physical properties, Japanese Patent Application Laid-Open No. 2000-289903 discloses a transport device that transports while applying tension in the width direction of the web when the solvent content is 50 to 12% by mass. A web width detecting means, a web holding means, and an invention that has two or more variable bending points, calculates the web width from a detection signal in web width detection, and changes the position of the bending point. Has been.

Furthermore, in order to improve the clipping property, prevent web breakage for a long period of time, and obtain a film with excellent quality, Japanese Patent Application Laid-Open No. 2003-033933 discloses the right and left sides of the web on the left and right sides near the entrance of the tenter. A web side edge curl prevention guide plate is disposed at least below the upper and lower side edges, and the web facing surface of the guide plate is arranged in the web conveying direction and the web. It is described that it comprises a contact metal part.
As a more preferred embodiment, the web contact resin portion of the web facing surface of the guide plate is disposed on the upstream side in the web conveyance direction, and the web contact metal portion is disposed on the downstream side, the web contact resin portion of the guide plate and The level difference (including the inclination) between the web contact metal parts is within 500 μm, and the width of the guide plate web contact resin part and the web contact metal part contacting the web is 2 to 2, respectively. It is 150 mm, the distance of the web contact direction of the web contact resin part of the guide plate and the web contact metal part in the web conveyance direction is 5 to 120 mm, respectively, and the web contact resin part of the guide plate is made of metal. It is provided on the guide board by surface resin processing or resin coating, the web contact resin part of the guide plate is made of a single resin, on the left and right side edges of the web The distance between the web facing surfaces of the guide plates disposed above and below is 3 to 30 mm, and the distance between the web facing surfaces of the upper and lower guide plates at the left and right side edges of the web is In the width direction of the web and inward, it is enlarged at a rate of 2 mm or more per 100 mm width, and both the upper and lower guide plates have a length of 10 to 300 mm at the left and right side edges of the web. The upper and lower guide plates are arranged so as to be displaced back and forth along the web conveyance direction, and the distance of the deviation between the upper and lower guide plates is −200 to +200 mm, the upper guide plate The web facing surface of the guide plate is made of resin or metal only, the web contact resin portion of the guide plate is made of Teflon (registered trademark), and the web contact metal portion is It is disclosed that it is made of stainless steel, the web facing surface of the guide plate, or the surface roughness of the web contact resin portion and / or the web contact metal portion provided on the guide plate is 3 μm or less. Has been.
Further, it is also described that the installation position of the upper and lower guide plates for preventing web side edge curl generation is preferably between the peeling side end portion of the support and the tenter introduction portion, and more preferably installed near the tenter entrance. Has been.

Furthermore, in order to prevent the cutting and unevenness of the web that occurs during drying in the tenter, Japanese Patent Application Laid-Open No. 11-048271 discloses that after the peeling, the width of the web is increased by 50-12 wt%. An invention is described in which the film is stretched and dried, and a pressure of 0.2 to 10 KPa is applied from both sides of the web by a pressure device when the solvent content of the web is 10 wt% or less.
As a more preferred embodiment, when applying pressure using a nip roll as a method of finishing applying tension when the solvent content is 4% by mass or more or applying pressure from both sides of the web (film), the number of nip roll pairs is from 1. It is also disclosed that about 8 sets are preferable, and the temperature when pressurizing is preferably 100 to 200 ° C.

Japanese Patent Laid-Open No. 2002-036266, which is an invention for obtaining a high-quality thin TAC having a thickness of 20 to 85 μm, has, as a preferred mode, tension acting on the web along the conveying direction before and after the tenter. The difference of 8 N / mm ² or less, after the peeling process, a preheating process for preheating the web, a stretching process for stretching the web using a tenter after the preheating process, and after the stretching process, And a relaxation step of relaxing the web by an amount smaller than the stretching amount in the stretching step.
The temperature T ₁ in the preheating step and the stretching step is (glass transition temperature Tg-60 of the film) ° C. or higher, and the temperature T ₂ in the relaxation step is (T ₁ −10) ° C. or lower, the stretching step The ratio of the web stretched in the step is 0-30% in terms of the web width immediately before entering the stretching step, the web stretch ratio in the relaxation step is made -10-10%, etc. .

  Further, JP 2002-225054 A, which aims to have a dry film thickness of 10 to 60 μm and a low durability that is lightweight and moisture-permeable, has a residual solvent amount of 10 mass after peeling. %, Gripping both ends of the web with clips, suppressing drying shrinkage by holding the width, and / or stretching in the width direction, S = {(Nx + Ny) / 2} Form a film having a plane orientation degree (S) represented by -Nz of 0.0008 to 0.0020 (where Nx is the refractive index in the direction of highest refractive index in the plane of the film, and Ny is Nx The refractive index in the direction perpendicular to the surface, Nz is the refractive index in the film thickness direction), the time from casting to peeling is set to 30 to 90 seconds, the web after peeling in the width direction and Stretching in the longitudinal direction is disclosed.

  Japanese Patent Application Laid-Open No. 2002-341144 discloses a solution having a stretching process in which the mass concentration of the retardation control (raising) agent has a higher optical distribution toward the center in the film width direction in order to suppress optical unevenness. A membrane method is described.

Furthermore, in Japanese Patent Application Laid-Open No. 2003-071863, which is an invention for obtaining a film that does not cause fogging, the draw ratio in the width direction is preferably 0 to 100%, and when used as a polarizing plate protective film 5 to 20% is more preferable, and 8 to 15% is further preferable.
On the other hand, the stretching ratio in the lateral direction when used as a retardation film is more preferably 10 to 40%, still more preferably 20 to 30%, and Ro can be controlled by the stretching ratio. It is disclosed that the higher one is preferable because the flatness of the finished film is excellent.
Further, when the tenter is used, the residual solvent amount of the film is preferably 20 to 100% by mass at the start of the tenter, and drying is performed while the tenter is applied until the residual solvent amount of the film becomes 10% by mass or less. It is shown that 5 mass% or less is more preferable.
Moreover, 30-150 degreeC is preferable for the drying temperature in the case of performing a tenter, 50-120 degreeC is more preferable, 70-100 degreeC is still more preferable, and the one where a drying temperature is lower has transpiration of a ultraviolet absorber, a plasticizer, etc. It is also disclosed that the process contamination can be reduced, but the higher the drying temperature, the better the flatness of the film.

Japanese Patent Laid-Open No. 2002-248639, which is an invention that reduces vertical and horizontal dimensional fluctuations during storage under high temperature and high humidity conditions, continuously casts a cellulose ester solution on a support. In the manufacturing method of the film peeled and dried, the invention is dried so that the drying shrinkage rate satisfies the following formula: 0 ≦ dry shrinkage rate (%) ≦ 0.1 × residual solvent amount (%) when peeling Is described.
Furthermore, as a preferred embodiment, when the residual solvent amount of the cellulose ester film after peeling is in the range of 40 to 100% by mass, at least the residual solvent amount is 30% by mass while holding both ends of the cellulose ester film by tenter conveyance. The amount of residual solvent at the tenter transport entrance of the cellulose ester film after peeling is 40 to 100% by mass, the amount of residual solvent at the exit is 4 to 20% by mass, and the cellulose ester film is transported by tenter transport. It is disclosed that the tension to be conveyed increases from the entrance to the exit of the tenter conveyance, the tension to convey the cellulose ester film by the tenter conveyance and the tension in the width direction of the cellulose ester film are substantially equal. Yes.

  In order to obtain a film having a thin film thickness and excellent optical isotropy and flatness, Japanese Patent Application Laid-Open No. 2000-239403 discloses a residual solvent ratio X at the time of peeling and a residual solvent at the time of introduction into a tenter. It is disclosed that film formation is performed with the relationship of the rate Y being in the range of 0.3X ≦ Y ≦ 0.9X.

  Japanese Patent Application Laid-Open No. 2002-286933 includes a method of stretching a film to be formed by casting, a method of stretching under heating conditions and a method of stretching under solvent-containing conditions, and stretching under heating conditions. In some cases, it is preferable to stretch at a temperature below the glass transition point of the resin. On the other hand, when the cast film is stretched under solvent-impregnated conditions, the once dried film is contacted with the solvent again. It is disclosed that it can be impregnated with a solvent and stretched.

-Melt film formation The film used as the raw material may be manufactured by a melt film formation method. In the melt film formation method, raw materials such as raw materials such as polymers and additives may be heated and melted, and this may be formed into a film by extrusion injection molding. May be used.

  The temperature for heating and melting is not particularly limited as long as both raw material polymers are uniformly melted, and can be appropriately selected according to the purpose. For example, heating to a temperature higher than the melting point or the softening point is performed. In order to obtain a uniform film, a temperature higher than the melting point of the starting polymer is preferable, a temperature higher than the melting point by 5 to 40 ° C. is more preferable, and heating to a temperature higher by 8 to 30 ° C. than the melting point may be performed. Further preferred.

The film used in the method for producing the negative A plate of the present invention may contain components other than the negative birefringent material. Hereinafter, additives that can be added to the film will be described. The additive may be contained in a layer containing a negative birefringent material, or when the film also has other layers other than a layer containing a negative birefringent material. , May be added to the other layers.
-Ultraviolet absorber An ultraviolet absorber may be added to the film.
The ultraviolet absorber is not particularly limited and may be appropriately selected depending on the purpose. For example, salicylic acid ester, benzophenone, benzotriazole, benzoate, cyanoacrylate, nickel complex, and the like A benzophenone series, a benzotriazole series, or a salicylic acid ester series is preferable.

  0.001-5 mass% is preferable with respect to a polymer, and, as for the addition amount of a ultraviolet absorber, 0.01-1 mass% is more preferable. If the addition amount is 0.001% by mass or more, the effect of addition can be sufficiently exerted, and if the addition amount is 5% by mass or less, it is preferable because bleeding out of the ultraviolet absorber to the film surface can be suppressed.

  Further, the ultraviolet absorber may be added simultaneously with the dissolution of the polymer, or may be added to the dope after the dissolution (in the case of solution casting). In particular, a mode in which a UV absorber solution is added to the dope immediately before casting using a static mixer or the like is preferable because the spectral absorption characteristics can be easily adjusted.

-Deterioration preventing agent Moreover, you may add a deterioration preventing agent to the said film in order to prevent deterioration and decomposition | disassembly.
Examples of the deterioration preventing agent include butylamine, hindered amine compounds (JP-A-8-325537), guanidine compounds (JP-A-5-271471), benzotriazole-based UV absorbers (JP-A-6-235819), and benzophenones. Examples thereof include compounds such as UV absorbers (JP-A-6-118233).

-Dye Moreover, you may add the dye for hue adjustment to the said film. The content of the dye is preferably 10 to 1,000 ppm, more preferably 50 to 500 ppm in terms of the mass ratio with respect to the polymer. By containing the dye in this way, the light piping of the film can be reduced and the yellowness can be improved. These compounds are preferably added to the polymer solution or kneaded when the polymer is melted.

-Matting agent fine particles Moreover, you may add fine particle as a matting agent to the said film. Fine particles used 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, magnesium silicate and calcium phosphate. It is done. The fine particles preferably contain silicon from the viewpoint of low turbidity, and silicon dioxide is particularly preferred.

  The fine particles of silicon dioxide preferably have a primary average particle diameter of 20 nm or less and an apparent specific gravity of 70 g / L or more. Those having an average primary particle size as small as 5 to 16 nm are more preferred because they can reduce the haze of the film. The apparent specific gravity is preferably 90 to 200 g / L or more, and more preferably 100 to 200 g / L or more. A higher apparent specific gravity is preferable because a high-concentration dispersion can be produced, and haze and aggregates are improved.

  When silicon dioxide fine particles are used as the matting agent, the amount used is preferably 0.01 to 0.3 parts by mass with respect to 100 parts by mass of the polymer component.

These fine particles usually form secondary particles having an average particle diameter of 0.1 to 3.0 μm, but are present as aggregates of primary particles in the film, and 0.1 to 3.0 μm on the film surface. Form irregularities.
The average particle size of the secondary particles is preferably 0.2 μm or more and 1.5 μm or less, more preferably 0.4 μm or more and 1.2 μm or less, and further preferably 0.6 μm or more and 1.1 μm or less. If the average particle size is 1.5 μm or less, the haze will not be too strong, and if it is 0.2 μm or more, the effect of preventing squeezing will be sufficiently exerted.

  The primary and secondary particle diameters of the fine particles are determined by observing the particles in the film with a scanning electron microscope and using the diameter of a circle circumscribing the particles as the particle diameter. Also, 200 particles are observed at different locations, and the average value is taken as the average particle diameter.

  As the fine particles of silicon dioxide, for example, commercially available products such as “Aerosil” R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600 (above, manufactured by Nippon Aerosil Co., Ltd.) can be used. . Zirconium oxide fine particles are commercially available under the trade names of “Aerosil” R976 and R811 (manufactured by Nippon Aerosil Co., Ltd.), and can be used.

  Among these, “Aerosil 200V” and “Aerosil R972V” are fine particles of silicon dioxide having a primary average particle diameter of 20 nm or less and an apparent specific gravity of 70 g / L or more. This is particularly preferable because the effect of reducing the coefficient of friction is large while keeping it low.

In the present invention, in order to obtain an optical compensation film containing particles having a small secondary average particle size, several methods are conceivable when preparing a dispersion of fine particles.
For example, there is a method in which a fine particle dispersion in which a solvent and fine particles are mixed with stirring is prepared in advance, this fine particle dispersion is added to a small amount of separately prepared polymer solution, dissolved by stirring, and further mixed with the main polymer dope solution.
This method is a preferable preparation method in that the dispersibility of the silicon dioxide fine particles is good and the silicon dioxide fine particles are more difficult to reaggregate.
In addition to this, a small amount of polymer is added to the solvent and dissolved by stirring. Then, fine particles are added to this and dispersed with a disperser. This is used as a fine particle additive solution, and this fine particle additive solution is sufficiently mixed with the dope solution using an in-line mixer. There is also a method of mixing.
In the present invention, although not limited to these methods, the concentration of silicon dioxide when the silicon dioxide fine particles are mixed and dispersed with a solvent or the like is preferably 5 to 30% by mass, and 10 to 25% by mass. Is more preferable, and 15-20 mass% is still more preferable.
A higher dispersion concentration is preferable because the liquid turbidity with respect to the added amount is lowered, and haze and aggregates are improved. The addition amount of the matting agent in the final polymer dope solution is preferably 0.01 to 1.0 g, more preferably 0.03 to 0.3 g, and further 0.08 to 0.16 g per 1 m ^2. preferable.

  The solvent used is preferably lower alcohols such as methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol and the like. Although it does not specifically limit as solvents other than a lower alcohol, It is preferable to use the solvent used at the time of film forming.

[Negative A plate]
The present invention also provides a long negative A plate having at least one layer containing a material having a negative intrinsic birefringence value and having an in-plane slow axis parallel to the longitudinal direction. Related. The long negative A plate is cut into a size that can be incorporated into a liquid crystal display device in use. Specifically, it is cut into a size of about 20 to 1200 mm in length and about 20 to 1200 mm in width.
According to the production method of the present invention, a long negative A plate having an in-plane slow axis parallel to the longitudinal direction can be produced while controlling optical characteristics. In the present specification, the “long shape” means a shape having a length of 10 to 5000 m and a width of 200 to 2000 mm. Of course, a folded form and a rolled form are also included.

The negative A plate of the present invention preferably satisfies the following formulas (1) and (2) when used for optical compensation of a liquid crystal display device, particularly an IPS or VA mode liquid crystal display device.
Formula (1): 50 nm ≦ Re (550) ≦ 300 nm
Formula (2): −0.6 ≦ Rth (550) / Re (550) ≦ −0.4
Regarding the formula (1), Re (550) is preferably 80 to 250 nm, and Re (550) is more preferably 100 to 200 nm. In the negative A plate of the present invention, Rth (550) / Re (550) is preferably −0.57 to −0.43 with respect to the formula (2), and −0.55 to − More preferably, it is 0.45.

In addition, the negative A plate of the present invention preferably satisfies the following characteristics.
Water content The negative A plate of the present invention preferably has an equilibrium water content of 1.0% or less at 25 ° C. and 80% RH in order to reduce color change with time of the liquid crystal display device.
The moisture content was measured using a Karl Fischer using a film sample 7 mm × 35 mm, using a moisture measuring device (CA-03, manufactured by Mitsubishi Chemical Corporation) and a sample drying device (VA-05, manufactured by Mitsubishi Chemical Corporation). Measure by the method. It is calculated by dividing the amount of water (g) by the sample mass (g).

-Haze Moreover, it is preferable that the haze of the negative A plate of this invention is 0.01 to 2% of range.
In the present invention, the haze is measured according to JIS K-6714 with a film sample of 40 mm × 80 mm at 25 ° C. and 60% RH with a haze meter (HGM-2DP, manufactured by Suga Test Instruments Co., Ltd.).

-Dimensional change In addition, the negative A plate of the present invention has a dimensional change when it is allowed to stand for 24 hours under conditions of 60 ° C and 95% RH, and is allowed to stand for 24 hours under conditions of 90 ° C and 5% RH. It is preferable that the dimensional change when placed is in the range of 0 to 5%.

-Photoelastic coefficient Further, the negative A plate of the present invention has a photoelastic coefficient of 50 × 10 ⁻¹³ cm ² / dyne or less in order to improve uniformity when it is attached to a liquid crystal display device. preferable.
As a specific measuring method, a tensile stress is applied to the long axis direction of a film sample 10 mm × 100 mm, and the retardation at that time is measured with an ellipsometer (M150, manufactured by JASCO Corporation). The photoelastic coefficient is calculated from the amount of change in retardation with respect to.

-Humidity dependence of Rth (550) It is preferable that the negative A plate of this invention satisfy | fills following numerical formula (A).
Formula (A):
10 ≧ | Rth (550) 10% RH−Rth (550) 60% RH |
In the formula (A), Rth (550) 10% RH and Rth (550) 60% RH are Rth (550) at 25 ° C., 10%, and 60% RH, respectively.
| Rth (550) 10% RH-Rth (550) 60% RH | is more preferably 5 nm or less.

The negative A plate of the present invention is once formed into a long shape, then continuously or once wound into a roll shape, stored and transported, and then cut into a size that can be incorporated into a liquid crystal display device. May be used.
Further, as will be described later, it may be used in a long form, after being laminated with a polarizing film and a roll-to-roll, and then cut into a size that can be incorporated into a liquid crystal display device.

[Polarizing plate and manufacturing method thereof]
The present invention, while transporting a film composed of one layer or two or more layers containing a material having a negative intrinsic birefringence value, is stretched in the width direction perpendicular to the transport direction and is contracted in the transport direction so as to be negative. A method for producing a polarizing plate, comprising: a step of forming a negative A plate; and a lamination step of laminating the negative A plate and a polarizer in a long state; and the negative A plate and the polarizer of the present invention. It also relates to at least a polarizing plate. In the polarizing plate of the present invention, it is preferable that the negative A plate is bonded to the surface of the polarizing film via an adhesive. In the case where another polymer film or the like is disposed between the polarizing film and the negative A plate, the film is preferably optically isotropic.
The polarizing plate of the present invention is preferably produced by utilizing the production method of the present invention. When the production method of the present invention is used, a polarizing plate in which the absorption axis of the polarizer and the in-plane slow axis of the negative A plate are aligned in the same direction can be continuously produced in a long shape. Examples of the long form include a shape having a width of about 0.2 to 3 m and a length of about 20 to 10,000 m. For example, the negative A plate manufactured in a long shape manufactured by the manufacturing method of the present invention is temporarily wound into a roll, while a long polarizing film wound in a roll is separately prepared, By laminating both of them in a roll-to-roll manner, it is possible to continuously produce a polarizing plate in which the in-plane slow axis of the negative A plate and the absorption axis of the polarizing film are in the same direction.

Bonding is preferably performed using an adhesive. Although it does not restrict | limit especially about an adhesive agent, PVA-type resin (Including modified PVA, such as an acetoacetyl group, a sulfonic acid group, a carboxyl group, an oxyalkylene group), a boron compound aqueous solution, etc. can be used, Especially, PVA-type resin is used. preferable.
The thickness of the adhesive layer is preferably 0.01 to 10 μm after drying, and more preferably 0.05 to 5 μm.

  Bonding may be performed while holding both ends of the negative A plate during the drying process, or may be performed after being released from the both end holding portions after drying. It is preferable to wear the ears after bonding, and in the former case, both ends are bonded after being bonded to the polarizing film, and in the latter case, both ends are preferably set before being bonded to the polarizing film. As a method for cutting off the ears, general techniques such as a method of cutting with a cutter such as a blade or a method of using a laser can be used.

  After bonding, it is preferable to heat in order to dry the adhesive and improve the polarization performance. The heating conditions vary depending on the adhesive, but in the case of an aqueous system, 30 ° C or higher is preferable, 40 to 100 ° C is more preferable, and 50 to 90 ° C is further preferable. It is more preferable in terms of performance and production efficiency that these processes are manufactured in a consistent line.

The negative A plate may be subjected to a surface treatment to improve adhesion.
As the surface treatment, for example, glow discharge treatment, ultraviolet irradiation treatment, corona treatment, flame treatment, acid or alkali treatment can be used.
The glow discharge treatment here may be low-temperature plasma that occurs under a low pressure gas of 10 ^{−3 to} 20 Torr, and plasma treatment under atmospheric pressure is also preferred.
Plasma-excitable gas refers to a gas that is plasma-excited under the above conditions, such as argon, helium, neon, krypton, xenon, nitrogen, carbon dioxide, chlorofluorocarbons such as tetrafluoromethane, and mixtures thereof. Can be mentioned.
As for these, the Japan Institute of Invention Disclosure Technical Bulletin No. 2001-1745 (issued March 15, 2001, Invention Association) p. 30-32.
Note that, in the plasma treatment at atmospheric pressure which has been attracting attention in recent years, for example, irradiation energy of 20 to 500 kGy is used under 10 to 1,000 keV, and more preferably irradiation energy of 20 to 300 kGy is used under 30 to 500 keV. .

  As the polarizing film, for example, a polarizing film made of a polyvinyl alcohol film or the like can be dyed with iodine and stretched. You may implement the drying process which reduces a volatile matter rate after extending | stretching. It is also preferable that the drying is performed by attaching a negative A plate or other protective film and then performing a heating step.

When another polymer film is present as a polarizing film protective film between the polarizing film and the negative A plate, the film is preferably substantially isotropic, specifically, in-plane The retardation Re is preferably 0 to 10 nm, more preferably 0 to 7 nm, and further preferably 0 to 5 nm. The retardation Rth in the thickness direction is preferably −25 to 25 nm, more preferably −15 to 15 nm, and particularly preferably −10 to 10 nm.
Moreover, when bonding the negative A plate of this invention on an isotropic film, it is preferable to use an isotropic adhesive. The isotropic film is preferably a cellulose acylate film.

  The polarizing plate of the present invention preferably has the negative A plate of the present invention on one surface of the polarizing film and also has a protective film on the other surface. The protective film is preferably a cellulose acylate film.

One aspect of the polarizing plate of the present invention is an aspect having the polarizing film, the negative A plate of the present invention (also serving as a protective film for the polarizing film), and the second retardation film in this order. In this aspect, the combination of the retardation of the second retardation film and the slow axis is preferably any of the following.
First Preferred Example The in-plane slow axis of the second retardation film is in a direction parallel to the absorption axis of the polarizing film, and the second retardation film satisfies the following optical characteristics.
50 nm ≦ Re (550) ≦ 150 nm
30 nm ≦ Rth (550) ≦ 100 nm
Second Preferred Example The in-plane slow axis of the second retardation film is in a direction perpendicular to the absorption axis of the polarizing film, and the second retardation film satisfies the following optical characteristics.
50 nm ≦ Re (550) ≦ 300 nm
−200 nm ≦ Rth (550) ≦ −30 nm

The optical properties and durability (short-term and long-term storage stability) of the polarizing plate of the present invention should be equal to or better than those of a commercially available super high contrast product (for example, HLC2-5618 manufactured by Sanlitz Co., Ltd.). Is preferred.
Specifically, the visible light transmittance is 42.5% or more, and the degree of polarization {(Tp−Tc) / (Tp + Tc)} ^1/2 ≧ 0.9995 (where Tp is parallel transmittance and Tc is orthogonal transmission) The change rate of the light transmittance before and after being left in an atmosphere of 60 ° C. and humidity 90% RH for 500 hours and 80 ° C. in a dry atmosphere is 3% or less based on the absolute value. Is preferable, and 1% or less is more preferable. The rate of change in the degree of polarization is preferably 1% or less, more preferably 0.1% or less, based on the absolute value.

In the polarizing plate of the present invention, at least one layer of a hard coat layer, an antiglare layer or an antireflection layer is provided on the surface of the protective film on the at least one side of the polarizing plate (the surface on the viewing side). Is preferred.
That is, when the polarizing plate is used for a liquid crystal display device, it is preferable to provide a functional film such as an antireflection layer on the protective film disposed on the side opposite to the liquid crystal cell. It is preferable to provide at least one layer of a coat layer, an antiglare layer or an antireflection layer.
In addition, it is not necessary to provide each layer as a separate layer, for example, by providing an antireflection layer and a hard coat layer with an antiglare function, instead of providing two layers of an antireflection layer and an antiglare layer, You may make it function as an anti-glare antireflection layer.

-Antireflection layer In the present invention, an antireflection layer in which at least a light scattering layer and a low refractive index layer are laminated in this order on the protective film of the polarizing plate, or a medium refractive index layer and a high refractive index on the protective film. An antireflection layer in which a layer and a low refractive index layer are laminated in this order is suitably provided. Preferred examples thereof are described below. In the former configuration, the specular reflectance is generally 1% or more, which is referred to as a low reflection (LR) film. In the latter configuration, it is possible to realize a mirror reflectivity of 0.5% or less, and this is called an Anti Reflection (AR) film.

-LR film A preferable example of an antireflection layer (LR film) in which a light scattering layer and a low refractive index layer are provided on a protective film of a polarizing plate will be described.
In the light scattering layer, mat particles are preferably dispersed. The refractive index of the material other than the mat particles in the light scattering layer is preferably in the range of 1.50 to 2.00, and the low refractive index The refractive index of the refractive index layer is preferably in the range of 1.20 to 1.49.
In the present invention, the light scattering layer has both antiglare properties and hard coat properties, and may be a single layer or a plurality of layers, for example, two to four layers.

  The antireflection layer has an uneven surface shape, centerline average roughness Ra is 0.08 to 0.40 μm, 10-point average roughness Rz is 10 times or less Ra, average unevenness distance Sm is 1 to 100 μm, unevenness The standard deviation of the height of the convex part from the deepest part is 0.5 μm or less, the standard deviation of the average unevenness distance Sm with respect to the center line is 20 μm or less, and the surface with the inclination angle of 0 to 5 ° is 10% or more. It is preferable that it is designed so that sufficient anti-glare property and visual uniform matte feeling can be achieved.

Further, the ratio of the minimum value to the maximum value of the reflectance when the color of the reflected light under the C light source is in the range of a * value −2 to 2, b * value −3 to 3, and 380 to 780 nm is 0. It is preferable that the color is 5 to 0.99 because the color of the reflected light becomes neutral.
Furthermore, it is preferable that the b * value of the transmitted light under the C light source is 0 to 3 because the yellow color of white display when applied to a display device is reduced.
Furthermore, if a 120 μm × 40 μm grid is inserted between the surface light source and the antireflection layer and the luminance distribution is measured on the film, the standard deviation of the luminance distribution is 20 or less. Since glare when the polarizing plate of the invention is applied is reduced, it is preferable.

The antireflection layer that can be used in the present invention suppresses reflection of external light by setting its optical properties to a specular reflectance of 2.5% or less, a transmittance of 90% or more, and a 60 ° glossiness of 70% or less. This is preferable because visibility is improved. In particular, the specular reflectance is more preferably 1% or less, and further preferably 0.5% or less.
Moreover, haze 20-50%, ratio of internal haze / total haze value is 0.3-1, haze value after forming low refractive index layer from haze value to light scattering layer is within 15%, comb width Prevents glare on a high-definition LCD panel by setting the transmission image clarity at 0.5 mm to 20 to 50% and the transmittance ratio of vertical transmitted light / inclination 2 ° from the vertical to 1.5 to 5.0. This is preferable because blurring of characters and the like is reduced.

-Low refractive index layer 1.20-1.49 are preferable and, as for the refractive index of the low refractive index layer which can be used by this invention, 1.30-1.44 are more preferable. Furthermore, the low refractive index layer preferably satisfies the following formula (C) from the viewpoint of reducing the reflectance.
( _M / 4) λ × 0.7 <n _L d _L <(m / 4) λ × 1.3... Formula (C)
In the above formula (C), m is a positive odd number, n _L is the refractive index of the low refractive index layer, and d _L is the film thickness (nm) of the low refractive index layer. Further, λ is a wavelength, which is a value in the range of 500 to 550 nm.

[Liquid Crystal Display]
The present invention also relates to a liquid crystal display device having the negative A plate of the present invention and / or the polarizing plate of the present invention.
The liquid crystal display device of the present invention may be any of a reflection type, a semi-transmission type, a transmission type liquid crystal display device and the like. A liquid crystal display device generally includes a polarizing plate, a liquid crystal cell, and, if necessary, a retardation film, a reflective layer, a light diffusion layer, a backlight, a front light, a light control film, a light guide plate, a prism sheet, a color filter, etc. Although comprised from a member, in this invention, there is no restriction | limiting in particular except the point which makes it essential to use the polarizing plate of this invention. The liquid crystal cell is not particularly limited, and a general liquid crystal cell such as a liquid crystal layer sandwiched between a pair of transparent substrates provided with electrodes can be used. The transparent substrate constituting the liquid crystal cell is not particularly limited as long as the liquid crystal material constituting the liquid crystal layer is aligned in a specific alignment direction. Specifically, a transparent substrate in which the substrate itself has a property of orienting liquid crystals, a transparent substrate in which an alignment film having the property of orienting liquid crystals is provided, but the substrate itself lacks the alignment ability. Either can be used. Moreover, a well-known thing can be used for the electrode of a liquid crystal cell. Usually, it can be provided on the surface of the transparent substrate in contact with the liquid crystal layer, and when a substrate having an alignment film is used, it can be provided between the substrate and the alignment film. The material exhibiting liquid crystallinity for forming the liquid crystal layer is not particularly limited, and examples thereof include various ordinary low-molecular liquid crystalline compounds, high-molecular liquid crystalline compounds, and mixtures thereof that can constitute various liquid crystal cells. Moreover, a pigment | dye, a chiral agent, a non-liquid crystalline compound, etc. can also be added to these in the range which does not impair liquid crystallinity.

  In addition to the electrode substrate and the liquid crystal layer, the liquid crystal cell may include various components necessary for forming various types of liquid crystal cells described later. As the liquid crystal cell system, a TN (Twisted Nematic) system, a STN (Super Twisted Nematic) system, an ECB (Electrically Controlled Birefringence) system, an IPS (In-Plane Switching) system, a VA (In-Plane Switching) system, a VA (In-Plane Switching) system, a VA (In-Plane Switching) system, a VA (In-Plane Switching) system, Alignment), PVA (Patterned Vertical Alignment), OCB (Optically Compensated Birefringence), HAN (Hybrid Aligned Nematic), ASM crocell) method, halftone gray scale method, domain division method, or display method using ferroelectric liquid crystal or antiferroelectric liquid crystal. The driving method of the liquid crystal cell is not particularly limited, and a passive matrix method used for STN-LCD and the like, and an active matrix method using an active electrode such as a TFT (Thin Film Transistor) electrode and a TFD (Thin Film Diode) electrode, Any driving method such as a plasma addressing method may be used. A field sequential method that does not use a color filter may be used.

  The mode of the liquid crystal cell is not particularly limited, but is preferably an IPS mode, a VA mode, or an FFS mode.

  In an IPS mode liquid crystal cell, rod-like liquid crystal molecules are aligned substantially parallel to the substrate, and the liquid crystal molecules respond in a planar manner when an electric field parallel to the substrate surface is applied. In the IPS mode, black is displayed when no electric field is applied, and the transmission axes of the pair of upper and lower polarizing plates are orthogonal. A method of reducing leakage light at the time of black display in an oblique direction and improving a viewing angle using an optical compensation film is disclosed in JP-A-10-54982, JP-A-11-202323, and JP-A-9-292522. No. 11-133408, No. 11-305217, No. 10-307291, and the like.

Next, embodiments of the liquid crystal display device of the present invention will be described with reference to the drawings. In addition, the same number was attached | subjected to the same member in FIGS.
FIG. 1 is a schematic diagram showing a configuration of an embodiment of a liquid crystal display device in a horizontal alignment mode such as an IPS mode or an FFS mode.
The liquid crystal display device of FIG. 1 includes a pair of first polarizing film 3 and second polarizing film 8 arranged with the absorption axes 9 and 2 orthogonal to each other, and the pair of polarizing films 3 and 8. The liquid crystal cell 6 is disposed. Although omitted in the drawing, the liquid crystal cell 6 has a pair of substrates and a liquid crystal layer disposed between the pair of substrates, and the liquid crystal molecules in the liquid crystal layer are substantially relative to the substrate during black display. It is a so-called horizontal alignment mode liquid crystal cell that is aligned in parallel. A protective film is disposed on the cell side and the outer surface of the second polarizing film 8, and a protective film is disposed on the outer side of the first polarizing film 3.

The liquid crystal display device of FIG. 1 further includes a first retardation film (negative A plate of the present invention) 11 and a second retardation film disposed between the first polarizing film 3 and the liquid crystal cell 6. It has a film 13. The first retardation film 11 also functions as a protective film on the liquid crystal cell side of the first polarizing film 3.
The in-plane slow axes 12 and 14 of the first and second retardation films 11 and 13 are parallel to each other and substantially with respect to the major axis direction 5 of the liquid crystal molecules when the liquid crystal cell 6 displays black. Orthogonal.

In FIG. 1, any of the first and second polarizing films 3 and 8 may be a backlight side polarizing film or a viewing side polarizing film, but the first polarizing film 3 is on the backlight side. It is preferable that
In addition, the laminated body which consists of the 1st phase difference film 11, the 1st polarizing film 3, and the protective film 1 in FIG. 1 is a polarizing plate of this invention.

In FIG. 1, the first retardation film 11 is the negative A plate of the present invention, and preferably satisfies the following formulas (1) and (2).
Formula (1): 50 nm ≦ Re (550) ≦ 300 nm
Formula (2): −0.6 ≦ Rth (550) / Re (550) ≦ −0.4
Regarding the formula (1), Re (550) is preferably 50 to 200 nm, and Re (550) is more preferably 80 to 130 nm.

In FIG. 1, the second retardation film 13 is preferably a positive A plate. More specifically, it is preferable that the optical properties of the following formulas (10) and (11) are satisfied.
Formula (10): 50 nm ≦ Re (550) ≦ 150 nm
Formula (11): 30 nm ≦ Rth (550) ≦ 100 nm
As the second retardation film 13, various films such as a stretched polymer film and a laminated film having a retardation layer formed from a liquid crystal composition on the polymer film can be used. In addition, the first retardation film 11 may be used as a support, and a retardation layer made of a liquid crystal composition may be formed thereon by coating or the like, but the second retardation film is preferably a stretched film. .

  In FIG. 1, the protective film 7 of the second polarizing film 8 is preferably a substantially isotropic transparent protective film. Specifically, the substantially isotropic transparent protective film has an in-plane retardation of 0 to 10 nm and a retardation in the thickness direction of -20 to 20 nm. For example, cellulose having such optical properties Films containing acylates or cyclic polyolefins are preferred.

FIG. 3 is a schematic diagram showing a configuration of another embodiment of a liquid crystal display device in a horizontal alignment mode such as an IPS mode or an FFS mode.
In the liquid crystal display device of FIG. 3, the second retardation film 13 is provided between the protective film 7 of the second polarizing film 8 and the liquid crystal cell 6 and the first retardation film (negative A of the present invention). Plate) 11 is disposed between the first polarizing film 3 and the liquid crystal cell. The first and second retardation films 11 and 13 also serve as protective films on the liquid crystal cell side of the first and second polarizing films 3 and 8, respectively.

In FIG. 3, the first retardation film 11 has an optical characteristic in which the slow axis 12 is parallel to the absorption axis 2 of the first polarizing film 3 and satisfies the expressions (1) and (2). . The in-plane retardation Re (550) is preferably 50 to 200 nm, more preferably 70 to 150 nm, and still more preferably 80 to 130 nm.
In FIG. 3, the second retardation film 13 has an optical characteristic in which the slow axis 14 is parallel to the absorption axis 9 of the second polarizing film 8 and satisfies the expressions (1) and (2). Have The in-plane retardation Re (550) is preferably 100 to 300 nm, more preferably 130 to 250 nm, and still more preferably 150 to 230 nm. That is, in FIG. 3, the negative A plate of the present invention can also be used as the second retardation film 13.
In this case, it is preferable that both the first retardation film 11 and the second retardation film 13 are the negative A plate of the present invention. Of the two retardation films, only the second retardation film 13 may be the retardation film of the present invention.

In the liquid crystal display device of FIG. 3, the first and second polarizing films 3 and 8 may be either a backlight-side polarizing film or a viewing-side polarizing film, but the first polarizing film 3 is a backlight. The side is preferred.
In FIG. 3, at least one of the second polarizing film 8 and the first polarizing film 3 includes a retardation film laminated as a protective film, which is the polarizing plate of the present invention. Any of them is preferably the polarizing plate of the present invention.

FIG. 4 is a schematic diagram showing a configuration of another embodiment of a liquid crystal display device in a horizontal alignment mode such as an IPS mode or an FFS mode.
The liquid crystal display device of FIG. 4 has the same configuration as the liquid crystal display device of FIG. 1, but the slow axis 14 of the second retardation film 13 is orthogonal to the slow axis 12 of the first retardation film 11. It is different in that it is in the direction.
In FIG. 4, the first retardation film 11 has an optical characteristic in which the slow axis 12 is parallel to the absorption axis of the first polarizing film 3 and satisfies the expressions (1) and (2). . The in-plane retardation Re (550) is preferably 50 to 200 nm, more preferably 70 to 150 nm, and still more preferably 80 to 130 nm.

In FIG. 4, the second retardation film 13 preferably has an in-plane slow axis 14 orthogonal to the absorption axis of the first polarizing film 3 and satisfies the following expressions (12) and (13). .
Formula (12): 50 nm ≦ Re (550) ≦ 300 nm
Formula (13): −200 nm ≦ Rth (550) ≦ −30 nm
As the second retardation film 13, various films such as a stretched polymer film and a laminated film having a retardation layer formed from a liquid crystal composition on the polymer film can be used. In addition, the first retardation film 11 may be used as a support, and a retardation layer made of a liquid crystal composition may be formed thereon by coating or the like, but the second retardation film is preferably a stretched film. .

In the liquid crystal display device of FIG. 4, any of the first and second polarizing films 3 and 8 may be a backlight-side polarizing film or a viewing-side polarizing film, but the first polarizing film is The backlight side is preferable.
In addition, in FIG. 4, the 1st phase difference film 11, the 1st polarizing film 3, and the protective film 1 are the polarizing plates of this invention.

  In the configuration of FIG. 4, the second retardation film may be a stretched film or a film in which a retardation layer of a base film is laminated as long as it has the above optical characteristics. Moreover, although it may be the phase difference layer which used the 1st phase difference film as the base material, it is preferable that it is a stretched film.

  In FIG. 4, the protective film 7 of the second polarizing film 8 is preferably a substantially isotropic transparent protective film. Specifically, the substantially isotropic transparent protective film has an in-plane retardation of 0 to 10 nm and a retardation in the thickness direction of -20 to 20 nm. For example, cellulose having such optical properties Films containing acylates or cyclic polyolefins are preferred.

FIG. 5 is a schematic diagram showing a configuration of another embodiment of a liquid crystal display device in a horizontal alignment mode such as an IPS mode or an FFS mode.
In the liquid crystal display device of FIG. 5, the second retardation film 13 is provided between the protective film 7 of the second polarizing film 8 and the liquid crystal cell 6 and the first retardation film (negative A of the present invention). Plate) 11 is disposed between the first polarizing film 3 and the liquid crystal cell. The first and second retardation films 11 and 13 also serve as protective films on the liquid crystal cell side of the first and second polarizing films 3 and 8, respectively. Further, the major axis direction 5 of the liquid crystal molecules at the time of black display of the liquid crystal cell 6 is substantially parallel to the absorption axis 9 of the second polarizing film 8 and to the absorption axis of the first polarizing film 3. It is substantially orthogonal.

In FIG. 5, the first retardation film 11 has an optical characteristic in which the slow axis is parallel to the absorption axis 2 of the first polarizing film 3 and satisfies the expressions (1) and (2). The in-plane retardation Re (550) is preferably 100 to 300 nm, more preferably 130 to 250 nm, and still more preferably 150 to 230 nm.
In FIG. 5, the second retardation film 13 has substantially no in-plane retardation, and the in-plane retardation Re (550) is preferably 0 to 10 nm, more preferably 0 to 8 nm. Preferably, it is 0-5 nm.
The thickness direction retardation Rth (550) is preferably −200 to −30 nm, preferably −180 to −30 nm, and more preferably −160 to −80 nm.

In the liquid crystal display device of FIG. 5, any of the first and second polarizing films 3 and 8 may be a backlight-side polarizing film or a viewing-side polarizing film, but the first polarizing film is The backlight side is preferable.
In addition, in FIG. 5, the 1st phase difference film 11, the 1st polarizing film 3, and the protective film 1 are the polarizing plates of this invention.

FIG. 6 is a schematic diagram showing a configuration of an embodiment of a VA mode liquid crystal display device.
The liquid crystal display device of FIG. 6 includes a pair of first polarizing film 3 and second polarizing film 8 disposed between the absorption axes 9 and 2 orthogonal to each other, and the pair of polarizing films 3 and 8. And a liquid crystal cell 6 'disposed therein. Although not shown in the drawing, the liquid crystal cell 6 ′ has a pair of substrates and a liquid crystal layer disposed between the pair of substrates, and the liquid crystal molecules in the liquid crystal layer substantially correspond to the substrate during black display. This is a liquid crystal cell in a so-called vertical alignment mode, which is aligned orthogonally to each other. A protective film is disposed on the outer surfaces of the first and second polarizing films 3 and 8, respectively.

  The liquid crystal display device of FIG. 6 further includes a first retardation film (negative A plate of the present invention) 11 disposed between the second polarizing film 8 and the liquid crystal cell 6 ′, and the first It has the 2nd phase difference film 13 arrange | positioned between the polarizing film 3 and liquid crystal cell 6 '. The first and second retardation films 11 and 13 also function as protective films on the liquid crystal cell side of the second and first polarizing films 8 and 3, respectively.

  The VA mode liquid crystal cell 6 'is (1) a narrowly defined VA mode liquid crystal cell in which rod-like liquid crystal molecules are aligned substantially vertically when no voltage is applied, and are aligned substantially horizontally when a voltage is applied. (2) Liquid crystal cell (SID97, Digest of tech. Papers 28 (1997)) in which the VA mode is multi-domained (in MVA mode) for widening the viewing angle. 845), (3) liquid crystal cell in a mode (n-ASM mode) in which rod-like liquid crystalline molecules are substantially vertically aligned when no voltage is applied and twisted multi-domain alignment is applied when a voltage is applied (Preliminary Collection 58 of the Japanese Liquid Crystal Society) 59 (1998)) and (4) SURVAVAL mode liquid crystal cell (announced at LCD International 98) .

In FIG. 6, the first retardation film 11 has an in-plane slow axis parallel to the absorption axis of the second polarizing film 8 and optical characteristics satisfying the expressions (1) and (2). Have. The in-plane retardation Re (550) is preferably 100 to 250 nm, more preferably 120 to 200 nm, and still more preferably 130 to 180 nm.
In FIG. 6, the second retardation film 13 has substantially no in-plane retardation, and the in-plane retardation Re (550) is preferably 0 to 10 nm, more preferably 0 to 8 nm. Preferably, it is 0-5 nm. The thickness direction retardation Rth (550) is preferably 300 to 500 nm, preferably 350 to 450 nm, and more preferably 370 to 430 nm.

In FIG. 6, any of the first and second polarizing films 3 and 8 may be a backlight-side polarizing film or a viewing-side polarizing film, but the first polarizing film 3 is on the backlight side. It is preferable.
In addition, in FIG. 6, the laminated body which consists of the 1st phase difference film 11, the 2nd polarizing film 8, and the protective film 10 is a polarizing plate of this invention, and it is preferable to use for the visual recognition side polarizing plate.

FIG. 7 is a schematic view showing a configuration of another embodiment of the VA mode liquid crystal display device.
In the liquid crystal display device of FIG. 7, first and second retardation films 11 and 13 are laminated and disposed between the second polarizing film 8 and the liquid crystal cell 6 ′.
In FIG. 7, the first retardation film 11 has an in-plane slow axis 12 parallel to the absorption axis 9 of the second polarizing film 8 and optical characteristics satisfying the expressions (1) and (2). Have The in-plane retardation Re (550) is preferably 100 to 250 nm, more preferably 120 to 200 nm, and still more preferably 130 to 180 nm.
In FIG. 7, the second retardation film 13 has substantially no in-plane retardation, and the in-plane retardation Re (550) is preferably 0 to 10 nm, and preferably 0 to 8 nm. More preferably, it is still more preferable that it is 0-5 nm. The thickness direction retardation Rth (550) is preferably 300 to 500 nm, preferably 350 to 450 nm, and more preferably 370 to 430 nm.

In FIG. 7, any of the first and second polarizing films 3 and 8 may be a backlight-side polarizing film or a viewing-side polarizing film, but the first polarizing film 3 is on the backlight side. It is preferable.
In addition, in FIG. 7, the laminated body which consists of the protective film 10, the polarizing film 8, and the 1st phase difference film 11, or the laminated body which has the 2nd phase difference film 13 is a polarizing plate of this invention.

  In the embodiment of the IPS mode, the configurations of FIGS. 1, 3, 4, and 5 are preferable, and the configuration of FIG. 3 is particularly preferable. On the other hand, in the embodiment of the VA mode, both of the configurations of FIGS. 6 and 7 are preferable, and the configuration of FIG. 6 is particularly preferable.

Examples of the present invention will be described below, but the present invention is not limited to the following examples.
In the following examples, first, a negative A plate of the present invention was prepared, the negative A plate was used as a polarizing plate protective film, and a polarizing plate obtained by laminating a positive A plate on the negative A plate was used. A mounted IPS mode or VA mode liquid crystal display device was manufactured.

[Example 1]
(Preparation of negative A plate)
[1] layer composed of norbornene-based polymer [Nippon Zeon Co., Ltd., ZEONOR 1020, glass transition temperature 105 ° C.], styrene-maleic anhydride copolymer [Nova Chemical Japan Co., Ltd., Dilark D332, glass transition temperature 130 [2] layer consisting of [° C., oligomer content 3% by mass] and [3] layer consisting of a modified ethylene-vinyl acetate copolymer [Mitsubishi Chemical Corporation, Modic AP A543, Vicat softening point 80 ° C.] , [1] layer (15 μm) − [3] layer (5 μm) − [2] layer (100 μm) − [3] layer (5 μm) − [1] layer (15 μm) Obtained by coextrusion.
Next, the long unstretched laminate film 101 obtained above is used in the width direction by using a tenter having a structure in which the continuous long film is narrowed while the length of the tenter clip is held and conveyed. The film is sent to a stretching apparatus (trade name “FITZ” manufactured by Ichikin Kogyo Co., Ltd.), which has a process of stretching the film, and the film temperature is set to 140 ° C. After 30 seconds, the film is passed through the heating zone and then stretched. The film is subjected to relaxation and shrinkage by 0.85 times (shrinkage rate of 15%) and stretched in the width direction by 1.40 times by a tenter clip (stretching rate of 40%). Obtained.
Regarding the relationship between the stretch ratio and the shrinkage ratio in the stretch ratio formula (Z), in this embodiment, the stretch ratio is 40%, and the shrinkage ratio calculated by the stretch ratio formula (Z) is 5.5 to 25.5. The center is 15.5%. Therefore, the shrinkage rate of the present embodiment is a value close to the center value.

  Re and Rth at a wavelength of 550 nm of the obtained retardation film 111 were measured by KOBRA 21ADH (manufactured by Oji Scientific Instruments) according to the method described above. The in-plane retardation Re (550) is 90 nm, the thickness direction retardation Rth (550) is −45 nm, the in-plane slow axis is parallel to the longitudinal direction, and the variation is ± 0.05 °. The residual volatile component content was 0.01% by mass or less. That is, the retardation film 111 was a negative A plate having an in-plane slow axis parallel to the longitudinal direction.

(Preparation of positive A plate)
A film composed of a norbornene polymer [Nippon ZEON Co., Ltd., ZEONOR 1420, glass transition temperature 135 ° C.] is longitudinally uniaxially stretched by a nip roll at a temperature of 139 ° C. and a magnification of 1.1 times, and is a retardation film having a thickness of 100 μm. 112 was obtained.
The obtained film had an in-plane retardation Re (B) of 90 nm, a thickness direction retardation Rth (B) of 45 nm, and a residual volatile component content of 0.01% by mass or less. That is, the produced retardation film 112 was a positive A plate.

(Preparation of polarizing plate)
<< Preparation of backlight-side polarizing plate >>
A polarizing film was prepared by adsorbing iodine to the stretched polyvinyl alcohol film, and the retardation film 111 was attached to one surface of the polarizing film with a roll to roll using an adhesive.
In addition, a commercially available cellulose triacylate film (Fujitac TD80UF, manufactured by Fuji Film Co., Ltd.) is subjected to saponification treatment, and a roll-to-roll is applied to the other surface of the polarizing film using a polyvinyl alcohol-based adhesive. It dried at 70 degreeC for 10 minutes or more, and produced the polarizing plate (P1).
At this time, the absorption axis of the polarizing film and the slow axis of the retardation film 111 were arranged in parallel.

Furthermore, using a pressure-sensitive adhesive on the surface of the polarizing plate (P1) on which the retardation film 111 was laminated, the retardation film 112 was attached in a roll-to-roll manner to produce a polarizing plate (P11).
At this time, the absorption axis of the polarizing film and the slow axis of the retardation film 112 were arranged in parallel.

(Preparation of viewing side polarizing plate)
Iodine is adsorbed on the stretched polyvinyl alcohol film to prepare a polarizing film, and a commercially available cellulose acylate film (Z-TAC manufactured by Fuji Film Co., Ltd.) is saponified using a polyvinyl alcohol adhesive, and then rolled to Pasted with a roll.
Further, a commercially available cellulose triacylate film (Fujitac TD80UF, manufactured by Fuji Film Co., Ltd.) is subjected to saponification treatment, and using a polyvinyl alcohol adhesive, the other surface of the polarizing film is attached with a roll to roll, It dried at 70 degreeC for 10 minutes or more, and produced the polarizing plate (P20).

(Production of liquid crystal display device)
<< Production of IPS Mode Liquid Crystal Display >>
The liquid crystal cell was taken out from the IPS mode liquid crystal television TH-32LX500 (manufactured by Matsushita Electric Industrial Co., Ltd.), and the polarizing plate and the optical film attached to the viewing side and the backlight side were peeled off. In this liquid crystal cell, when no voltage was applied and during black display, the liquid crystal molecules were aligned substantially in parallel between the glass substrates, and the slow axis direction was horizontal to the screen.

The produced polarizing plate (P11) and polarizing plate (P20) were bonded to the upper and lower glass substrates of the parallel alignment cell using an adhesive. At this time, the polarizing plate (P11) is disposed as the polarizing plate on the backlight side, the polarizing plate (P20) is disposed as the polarizing plate on the viewing side, and the cellulose acylate film (Z -TAC) was bonded to the viewing side glass substrate, and the retardation film 112 included in the polarizing plate (P11) was bonded to the backlight side glass substrate.
Further, the polarizing axis (P11) and the slow axis of the liquid crystal cell were made parallel, and the polarizing axes (P11) and (P20) were arranged so that the absorption axes were orthogonal to each other.
The liquid crystal cell to which the polarizing plate was bonded in this manner was again incorporated into the liquid crystal television TH-32LX500 to produce a liquid crystal display device (L11).

The liquid crystal display device (L11) has the configuration shown in FIG. 1, in which the first polarizing film 3 is a backlight side polarizing plate, the first retardation film 11 is a retardation film 111, and the second position. The phase difference film 13 is a phase difference film 112. The second polarizing plate protective film (cell side) 7 is a cellulose acylate film (Z-TAC).
The manufactured liquid crystal display device (L11) was evaluated. The results are shown in Table 1.

<Evaluation of color shift>
The liquid crystal cell has a black display, the black display transmittance (%) at an azimuth angle of 45 degrees and a polar angle of 60 degrees, and an azimuth angle of 45 degrees polar angle of 60 degrees and an azimuth angle of 180 degrees and a polar angle of 60 degrees. A color shift Δx was obtained and evaluated based on the following evaluation criteria. The results are shown in Table 1.

[Evaluation criteria for color shift]
○: Δx is less than 0.02 Δ: Δx is 0.02-0.04
X: Δx is 0.04 to 0.06
XX: Δx is 0.06 or more

<Evaluation of viewing angle>
Further, using the measuring device (EZ-Contrast 160D, manufactured by ELDIM) as the contrast ratio, the transmittance ratio (white display / black display), the visual field is displayed in eight stages from black display (L1) to white display (L8). An angle (a polar angle range with a contrast ratio of 10 or more and no black-side gradation inversion) was measured and evaluated based on the following evaluation criteria. The results are shown in Table 1.

[Evaluation criteria for viewing angle (polar angle range with contrast ratio of 10 or more and no black-side gradation inversion)]
○: Polar angle of 80 ° or more in upper, lower, left and right △: Polar angle of 80 ° or more in three directions in upper, lower, left, right ×: Polar angle of 80 ° or more in two directions in upper, lower, left, right XX: More than 80 ° polar angle in one direction

[Example 2]
(Preparation of negative A plate)
As a material having a negative intrinsic birefringence value, a copolymer polycarbonate having a fluorene skeleton was used.
The polymerization of the polycarbonate was performed by an interfacial polycondensation method using a known phosgene. A reaction vessel equipped with a stirrer, a thermometer and a reflux condenser was charged with an aqueous sodium hydroxide solution and ion-exchanged water. A small amount of hydrosulfite was added. Next, methylene chloride was added thereto, and phosgene was blown in at about 20 ° C. over about 60 minutes. Further, p-tert-butylphenol was added for emulsification, and then triethylamine was added and stirred at 30 ° C. for about 3 hours to complete the reaction. After completion of the reaction, the organic phase was collected, and methylene chloride was evaporated to obtain a polycarbonate copolymer. The composition ratio of the obtained copolymer was almost the same as the charged amount ratio. The glass transition temperature was 235 ° C. The intrinsic viscosity of this copolymer determined at 20 ° C. in methylene chloride using an Ubbelohde viscosity tube was 0.8.

This copolymer was dissolved in methylene chloride to prepare a dope solution having a solid concentration of 18% by mass. A cast film was prepared from this dope solution, and a long unstretched film 103 having a thickness of 75 μm was obtained. The amount of residual solvent in this unstretched film was 0.9% by mass.
A step of stretching the long unstretched film 103 obtained above using a tenter having a structure that becomes narrow while a continuous long film is held and conveyed in the longitudinal direction of the tenter clip. The film is sent to a stretching device (trade name “FITZ” manufactured by Ichikin Kogyo Co., Ltd.), and the film temperature is set to 245 ° C., and after 30 seconds, the film is passed through the heating zone and then stretched. The film was subjected to relaxation shrinkage (shrinkage rate 15%), and the width direction was stretched 1.30 times with a tenter clip (stretching rate 30%) to obtain a retardation film 113 having a film thickness of 66 μm after stretching.
In this example, the stretch ratio is 30% and the shrinkage ratio calculated by the stretch ratio formula (Z) is 2.3 to 22.3. The center is 12.3%. Therefore, the shrinkage rate of the present embodiment is a value close to the center value.

  Re and Rth at a wavelength of 550 nm of the obtained retardation film 113 were measured with KOBRA 21ADH (manufactured by Oji Scientific Instruments) according to the method described above. The in-plane retardation Re (550) is 90 nm, the thickness direction retardation Rth (550) is −45 nm, the in-plane slow axis is a direction parallel to the longitudinal direction, and the variation is ± 0.05 °. The residual volatile component content was 0.01% by mass or less. That is, the retardation film 113 was a negative A plate having an in-plane slow axis parallel to the longitudinal direction.

(Preparation of polarizing plate)
<< Preparation of backlight-side polarizing plate >>
A polarizing plate (P2) was produced in the same manner as in Example 1 except that the retardation film 113 was used instead of the retardation film 111 in the production of the polarizing plate (P1) of Example 1 described above.

Furthermore, using a pressure-sensitive adhesive on the surface of the polarizing plate (P2) on which the retardation film 113 was laminated, the retardation film 112 was attached in a roll-to-roll manner to produce a polarizing plate (P12).
At this time, the absorption axis of the polarizing film and the slow axis of the retardation film 112 were arranged in parallel.

(Production of liquid crystal display device)
In the same manner as in Example 11 except that the polarizing plate (P12) was used instead of the polarizing plate (P11) in the mounting on the IPS panel of the above-described Example 1 (liquid crystal display device (L11)). (P12) and the polarizing plate (P20) were mounted on an IPS panel to produce a liquid crystal display device (L12).

The liquid crystal display device (L12) has the configuration shown in FIG. 1, wherein the first polarizing film 3 is a backlight side polarizing plate, the first retardation film 11 is a retardation film 113, and the second position. The phase difference film is the phase difference film 112. The second polarizing plate protective film 7 (cell side) is a cellulose acylate film (Z-TAC).
The produced liquid crystal display device (L12) was evaluated. The results are shown in Table 1.

[Comparative Example 1]
Sending a continuous film of the unstretched laminate 101 produced in Example 1 to a normal stretching apparatus having a step of stretching in the width direction using a tenter with a constant interval in the longitudinal direction of the tenter clip, The film was stretched 1.4 times at a temperature of 140 ° C. to obtain a retardation film 114 having a thickness of 100 μm after stretching.

<Optical properties of film>
Re and Rth at a wavelength of 550 nm of the retardation film 114 were measured by KOBRA 21ADH (manufactured by Oji Scientific Instruments) according to the method described above. The results are shown in Table 1.

(Preparation of polarizing plate)
<< Preparation of backlight-side polarizing plate >>
A polarizing plate (P3) was produced in the same manner as in Example 1 except that the retardation film 114 was used instead of the retardation film 111 in the production of the polarizing plate (P1) of Example 1 described above.

Furthermore, using a pressure-sensitive adhesive on the surface of the polarizing plate (P3) on which the retardation film 114 was laminated, the retardation film 112 was attached in a roll-to-roll manner to produce a polarizing plate (P13).
At this time, the absorption axis of the polarizing film and the slow axis of the retardation film 112 were arranged in parallel.

(Production of liquid crystal display device)
In the same manner as in Example 1 except that the polarizing plate (P13) was used instead of the polarizing plate (P11) in the mounting of the above-described Example 1 on the IPS panel (liquid crystal display device (L11)). (P13) and the polarizing plate (P20) were mounted on an IPS panel to produce a liquid crystal display device (L13).

The liquid crystal display device (L13) has the configuration shown in FIG. 1, in which the first polarizing film is a backlight side polarizing plate, the first retardation film 11 is a retardation film 114, and the second retardation film. The film 13 is a retardation film 112. The second polarizing plate protective film 7 (cell side) is a cellulose acylate film (Z-TAC).
The manufactured liquid crystal display device (L13) was evaluated. The results are shown in Table 1.

[Comparative Example 2]
The long film in which the unstretched laminate 101 produced in Example 1 is continuously stretched is uniaxially stretched with a nip roll at a temperature of 140 ° C. and a magnification of 1.4 times, and the retardation film 115 having a film thickness of 118 μm after stretching. Got. This retardation film 115 had an in-plane slow axis in the width direction perpendicular to the longitudinal direction.

(Preparation of polarizing plate)
<< Preparation of backlight-side polarizing plate >>
In the production of the backlight side polarizing plate (P11) of Example 1 described above, the backlight side polarizing plate (P14) was obtained in the same manner as in Example 1 except that the retardation film 115 was used instead of the retardation film 111. ) Was produced.

(Production of liquid crystal display device)
In the same manner as in Example 1 except that the polarizing plate (P14) was used instead of the polarizing plate (P11) in the mounting on the IPS panel of the above-described Example 1 (liquid crystal display device (L11)). (P14) and the polarizing plate (P20) were mounted on an IPS panel to produce a liquid crystal display device (L14).

The liquid crystal display device (L14) has the configuration shown in FIG. 2, wherein the first polarizing film 3 is a backlight-side polarizing plate, the first retardation film 11 is a retardation film 115, and the second position. The phase difference film 13 is a phase difference film 112. The second polarizing plate protective film 7 (cell side) is a cellulose acylate film (Z-TAC).
The manufactured liquid crystal display device (L14) was evaluated. The results are shown in Table 1.

From the results shown in Table 1, the following is clear.
The liquid crystal display devices L11 and L12 using the negative A plate of the present invention having a slow axis in the longitudinal direction and Rth (550) / Re (550) of −0.5 have good viewing angle and color shift. However, the liquid crystal display device L13 using Rth (550) / Re (550) outside the range of the present invention was inferior in both viewing angle and color shift.
Further, even when Rth (550) / Re (550) is −0.5, the liquid crystal display device L14 using a negative A plate having a slow axis in the width direction is inferior in both viewing angle and color shift. Met.

  Next, the present invention will be described by taking an IPS mode liquid crystal display device using two polarizing plates using the negative A plate of the present invention as a polarizing plate protective film as an example.

[Example 3]
(Preparation of negative A plate)
The laminate 101 produced in Example 1 has a step of stretching in the width direction using a tenter having a structure in which a continuous long film is narrowed while the length of the tenter clip is held and conveyed in the longitudinal direction. The film is sent to a stretching device (trade name “FITZ”, manufactured by Ichikin Kogyo Co., Ltd.), stretched after passing through the heating zone 30 seconds after setting the film temperature to 140 ° C., and the longitudinal direction of the film is relaxed to 0.75 times The film was shrunk (shrinkage rate 25%) and stretched 1.80 times in the width direction with a tenter clip (stretching rate 80%) to obtain a retardation film 116 having a thickness of 104 μm after stretching.
Re and Rth at a wavelength of 550 nm of the obtained retardation film 116 were measured with KOBRA 21ADH (manufactured by Oji Scientific Instruments) according to the method described above. The in-plane retardation Re (550) is 180 nm, the thickness direction retardation Rth (550) is -90 nm, the in-plane slow axis is parallel to the longitudinal direction, and the variation is ± 0.05 °. The residual volatile component content was 0.01% by mass or less. That is, the retardation film 116 was a negative A plate.

(Preparation of polarizing plate)
《Preparation of viewing side polarizing plate》
A polarizing film was prepared by adsorbing iodine to the stretched polyvinyl alcohol film, and a retardation film 116 was attached to one surface of the polarizing film with a roll to roll using an adhesive.
Further, a commercially available cellulose triacylate film (Fujitac TD80UF, manufactured by Fuji Film Co., Ltd.) is subjected to saponification treatment, and using a polyvinyl alcohol adhesive, the other surface of the polarizing film is attached with a roll to roll, It dried at 70 degreeC for 10 minutes or more, and produced the polarizing plate (P4).
At this time, the absorption axis of the polarizing film and the slow axis of the retardation film 116 were arranged in parallel.

[Production of liquid crystal display devices]
<< Production of IPS Mode Liquid Crystal Display >>
The liquid crystal cell was taken out from the IPS mode liquid crystal television TH-32LX500 (manufactured by Matsushita Electric Industrial Co., Ltd.), and the polarizing plate and the optical film attached to the viewer side and the backlight side were peeled off. In this liquid crystal cell, when no voltage was applied and during black display, the liquid crystal molecules were aligned substantially in parallel between the glass substrates, and the slow axis direction was horizontal to the screen.

The produced polarizing plate (P4) and the polarizing plate (P1) produced in Example 1 were bonded to the upper and lower glass substrates of the parallel alignment cell using an adhesive. At this time, the polarizing plate (P1) is arranged as the polarizing plate on the backlight side, the polarizing plate (P4) is arranged as the polarizing plate on the viewing side, and the retardation film 116 included in the polarizing plate (P4) is visually recognized. The retardation film 111 included in the polarizing plate (P1) was bonded so as to be in contact with the glass substrate on the backlight side so as to be in contact with the glass substrate on the side.
In addition, the polarizing axis (P1) and the slow axis of the liquid crystal cell were orthogonal to each other, and the polarizing axes (P1) and (P4) were orthogonal to each other.
The liquid crystal cell to which the polarizing plate was bonded in this manner was again incorporated into the liquid crystal television TH-32LX500 to produce a liquid crystal display device (L15).

The liquid crystal display device (L15) has the configuration shown in FIG. 3, in which the first polarizing film 3 is a backlight side polarizing plate, the first retardation film 11 is a retardation film 111, and the second position. The phase difference film is a phase difference film 116.
The manufactured liquid crystal display device (L15) was evaluated. The results are shown in Table 1.

[Example 4]
(Production of retardation film)
The long film in which the unstretched laminate 101 produced in Example 1 is continuously stretched is uniaxially stretched with a nip roll at a temperature of 140 ° C. and a magnification of 1.8 times, and a retardation film 117 having a thickness of 104 μm after stretching. Got.

(Optical properties of the film)
Re and Rth at a wavelength of 550 nm of the retardation film 117 were measured with KOBRA 21ADH (manufactured by Oji Scientific Instruments) according to the method described above. The results are shown in Table 2. The in-plane slow axis of this film coincided with the width direction orthogonal to the longitudinal direction.

<< Preparation of backlight-side polarizing plate >>
Using a pressure-sensitive adhesive on the surface of the polarizing plate (P1) prepared in Example 1 on which the retardation film 111 was laminated, the retardation film 117 was attached by roll-to-roll to prepare a polarizing plate (P15).

(Production of liquid crystal display device)
In the above-described IPS panel mounting of Example 3 (liquid crystal display device (L15)), the polarizing plate (P15) is used instead of the polarizing plate (P1), and the polarizing plate prepared in Example 1 is used instead of the polarizing plate (P3). A polarizing plate (P15) and a polarizing plate (P20) were mounted on an IPS panel in the same manner as in Example 2 except that (P20) was used, and a liquid crystal display device (L16) was produced.

The liquid crystal display device (L16) has the configuration shown in FIG. 4, in which the first polarizing film 3 is a backlight side polarizing plate, the first retardation film 11 is a retardation film 111, and the second position. The phase difference film 13 is a phase difference film 117. The second polarizing plate protective film 7 (cell side) is a cellulose acylate film (Z-TAC).
The manufactured liquid crystal display device (L16) was evaluated. The results are shown in Table 2.

[Comparative Example 3]
(Preparation of negative A plate)
Sending a continuous film of the unstretched laminate 101 produced in Example 1 to a normal stretching apparatus having a step of stretching in the width direction using a tenter with a constant interval in the longitudinal direction of the tenter clip, The film was stretched 1.8 times at a temperature of 140 ° C. to obtain a retardation film 118 having a thickness of 80 μm after stretching.

(Optical properties of the film)
Re and Rth at a wavelength of 550 nm of the retardation film 118 were measured with KOBRA 21ADH (manufactured by Oji Scientific Instruments) according to the method described above. The results are shown in Table 2.

(Preparation of polarizing plate)
<< Preparation of backlight-side polarizing plate >>
A polarizing plate (P5) was produced in the same manner as in Example 3 except that the retardation film 118 was used instead of the retardation film 116 in the production of the polarizing plate (P4) of Example 3 described above.

(Production of liquid crystal display device)
In the mounting on the IPS panel of Example 3 (liquid crystal display (L15)), the polarizing plate (P5) is used instead of the polarizing plate (P4), and the polarizing plate (P2) is used instead of the polarizing plate (P1). A polarizing plate (P5) and a polarizing plate (P2) were mounted on an IPS panel in the same manner as in Example 3 except that they were used, and a liquid crystal display device (L16) was produced.
Moreover, it evaluated similarly to the above-mentioned Example 1. The results are shown in Table 2.

From the results shown in Table 2, the following is clear.
The liquid crystal display device using the negative A plate of the present invention having a slow axis in the longitudinal direction and Rth (550) / Re (550) of −0.5 was good in both viewing angle and color shift. , Rth (550) / Re (550) out of the range of the present invention was inferior in both viewing angle and color shift.
The liquid crystal display devices of Example 3 and Example 4 have equally good viewing angles and color shifts, but with the configuration of Example 3, one film can be reduced and used. Considering that the number of bonding steps increases when the number of films to be added increases, the configuration of Example 3 is preferable because the productivity is very high.

The present invention has been described above by taking the IPS mode liquid crystal display device as an example. Next, the present invention will be described by taking a VA mode liquid crystal display device as an example.
[Example 5]
(Production of retardation film)
A commercially available cellulose acylate film (Fujitac TD80UF, manufactured by Fuji Film Co., Ltd.) was passed through a dielectric heating roll having a temperature of 60 ° C., and the film surface temperature was raised to 40 ° C. After 14 ml / m ^{2 was} applied by a bar coater and kept under a steam far infrared heater (manufactured by Noritake Co., Ltd.) heated to 110 ° C. for 10 seconds, 3 ml / pure water was also used using the same bar coater. m ^{2 was} applied. The film temperature at this time was 40 degreeC. Next, washing with a fountain coater and draining with an air knife were repeated three times, and then the film was retained in a drying zone at 70 ° C. for 2 seconds and dried.

――――――――――――――――――――――――――――――――――
<Alkaline solution A composition>
――――――――――――――――――――――――――――――――――
Potassium hydroxide 4.7 parts by weight Water 15.7 parts by weight Isopropanol 64.8 parts by weight Propylene glycol 14.9 parts by weight C ₁₆ H ₃₃ O (CH ₂ CH ₂ O) ₁₀ H (surfactant) 1.0 mass Department ――――――――――――――――――――――――――――――――――

<Preparation of optical compensation film F11>
(Production of negative C plate)
An alignment film coating solution having the following composition was continuously applied with a # 14 wire bar to the saponified surface of the long cellulose acylate film prepared above. The alignment film was formed by drying with warm air of 60 ° C. for 60 seconds and further with warm air of 100 ° C. for 120 seconds.
――――――――――――――――――――――――――
Composition of alignment film coating solution ――――――――――――――――――――――――――
The following modified polyvinyl alcohol 10 parts by weight Water 371 parts by weight Methanol 119 parts by weight Glutaraldehyde 0.5 parts by weight ――――――――――――――――――――――――――――

A coating liquid (S1) containing a discotic liquid crystalline compound having the following composition was prepared, and continuously applied with a # 12.0 wire bar on the prepared alignment film. The conveyance speed of the film was 20 m / min. The solvent was dried in a step of continuously heating from room temperature to 80 ° C., and then heated in a drying zone at 120 ° C. for 90 seconds to align the discotic liquid crystalline compound. Subsequently, the temperature of the film is maintained at 90 ° C., UV light is irradiated at 500 mJ / cm ² using a high-pressure mercury lamp, the orientation of the liquid crystal compound is fixed, the optically anisotropic layer B1 is formed, and the retardation film F11 was produced.

Composition of coating solution (S1) ――――――――――――――――――――――――――――――――――――
Composition of coating liquid (S1) containing discotic liquid crystal compound ――――――――――――――――――――――――――――――――――――
91 parts by mass of the following discotic liquid crystalline compound (I) ethylene oxide modified trimethylolpropane triacrylate (V # 360, manufactured by Osaka Organic Chemical Co., Ltd.) 9 parts by mass Photopolymerization initiator (Irgacure 907, manufactured by Ciba Geigy) 3 parts by mass Sensitizer (Kayacure DETX, manufactured by Nippon Kayaku Co., Ltd.) 1 part by mass Fluoropolymer A 0.4 parts by mass Methyl ethyl ketone 212 parts by mass ――――――――――――― ――――――――――――――――――――――

  The optical properties of the produced retardation film F11 were measured using an automatic birefringence meter (KOBRA-21ADH, manufactured by Oji Scientific Instruments). Re measured at a wavelength of 590 nm was 2 nm, and Rth was 400 nm.

(Preparation of polarizing plate)
<< Preparation of backlight-side polarizing plate >>
The phase difference F11 was saponified, iodine was adsorbed to the stretched polyvinyl alcohol film to produce a polarizing film, and one surface of the polarizing film was saponified using a polyvinyl alcohol-based adhesive. The phase difference film F11 was affixed with a roll to roll.
Further, a commercially available cellulose triacylate film (Fujitac TD80UF, manufactured by Fuji Film Co., Ltd.) is subjected to saponification treatment, and using a polyvinyl alcohol adhesive, the other surface of the polarizing film is attached with a roll to roll, It dried at 70 degreeC for 10 minutes or more, and produced the polarizing plate (P30).

(Preparation of negative A plate)
The laminate 101 produced in Example 1 has a step of stretching in the width direction using a tenter having a structure in which a continuous long film is narrowed while the length of the tenter clip is held and conveyed in the longitudinal direction. The film is sent to a stretching device (trade name “FITZ”, manufactured by Ichikin Kogyo Co., Ltd.), stretched after passing through the heating zone 30 seconds after setting the film temperature to 140 ° C., and the longitudinal direction of the film is relaxed to 0.82 times. The film was shrunk (shrinkage rate 18%), and the width direction was stretched 1.50 times by a tenter clip (stretching rate 80%) to obtain a retardation film 119 having a stretched film thickness of 114 μm.
Re and Rth at a wavelength of 550 nm of the obtained retardation film 116 were measured with KOBRA 21ADH (manufactured by Oji Scientific Instruments) according to the method described above. The in-plane retardation Re (550) is 150 nm, the thickness direction retardation Rth (550) is -75 nm, the in-plane slow axis is parallel to the longitudinal direction, and the variation is ± 0.05 °. The residual volatile component content was 0.01% by mass or less. That is, the retardation film 119 was a negative A plate.

《Preparation of viewing side polarizing plate》
Iodine was adsorbed on the stretched polyvinyl alcohol film to prepare a polarizing film, and a retardation film 119 was attached to one surface of the polarizing film with a roll to roll using an adhesive.
Further, a commercially available cellulose triacylate film (Fujitac TD80UF, manufactured by Fuji Film Co., Ltd.) is subjected to saponification treatment, and using a polyvinyl alcohol adhesive, the other surface of the polarizing film is attached with a roll to roll, It dried at 70 degreeC for 10 minutes or more, and produced the polarizing plate (P6).
At this time, the absorption axis of the polarizing film and the slow axis of the retardation film 119 were arranged in parallel.

(Production of liquid crystal display device)
<< Production of vertical alignment liquid crystal cell >>
1% by mass of octadecyldimethylammonium chloride (coupling agent) was added to a 3% by mass aqueous polyvinyl alcohol solution. This was spin-coated on a glass substrate with an ITO electrode, heat-treated at 160 ° C., and then rubbed to form a vertical alignment film. The rubbing treatment was performed so that the two glass substrates were in opposite directions. Two glass substrates were faced to each other so that the cell gap (d) was about 5.0 μm. A vertical alignment liquid crystal cell A was produced by injecting a liquid crystal compound (Δn: 0.06) mainly composed of ester and ethane into the cell gap. The product of Δn and d was 300 nm.

  The polarizing plate (P30) and the polarizing plate (P6) produced above were bonded to the upper and lower glass substrates of the vertical alignment liquid crystal cell using an adhesive. At this time, the polarizing plate (P30) is disposed as the polarizing plate on the backlight side, the polarizing plate (P6) is disposed as the viewing-side polarizing plate, and the retardation film F11 included in the polarizing plate (P30) is the backlight. Bonding was performed so that the retardation film 119 included in the polarizing plate (P6) was in contact with the glass substrate on the viewing side.

  The liquid crystal display device L18 has the configuration shown in FIG. 6, the first polarizing film 3 is a backlight-side polarizing plate, the second retardation film 13 is a retardation film F11, and the first polarizing film 3 Also serves as a protective film. The first retardation film 11 is a retardation film 119, which also serves as a protective film for the second polarizing film.

  The liquid crystal display device L18 produced above was evaluated for the front and oblique light leakage, and the color shift when viewed from the front and oblique by the following method, and are summarized in Table 3.

[Comparative Example 4]
(Preparation of polarizing plate)
A commercially available cellulose triacylate film (Fujitac TD80UF, Fuji) was prepared by adsorbing iodine to a stretched polyvinyl alcohol film to produce a polarizing film, and using a polyvinyl alcohol adhesive to saponify both surfaces of the polarizing film. Film product) was saponified, and was attached to the other surface of the polarizing film with a roll-to-roll using a polyvinyl alcohol-based adhesive, dried at 70 ° C. for 10 minutes or more, and polarizing plate (P40 ) Was produced.

  The backlight side polarizing plate (P30) and the viewing side polarizing plate (P6) are both polarized to the polarizing plate (P40) prepared above with respect to the liquid crystal display device L18 produced above, and a liquid crystal display device L19 is produced. In addition, the color shift when viewed from obliquely leaking light, front and obliquely was evaluated by the following method and summarized in Table 3.

(1) Light leakage (front)
A liquid crystal cell is placed on a Schaukasten set in a dark room without attaching a polarizing plate, and a luminance meter (spectral radiance meter CS-1000: Minolta Co., Ltd.) placed 1 m away in the normal direction. The luminance 1 was measured in ().
Subsequently, each liquid crystal display device having a polarizing plate bonded on the same Schaukasten as described above was placed, and the luminance 2 was measured in the same manner as described above.

(2) Leakage light (oblique)
A liquid crystal cell is placed on a Schaukasten set in a dark room without attaching a polarizing plate, and is oriented 45 degrees to the left with respect to the rubbing direction of the liquid crystal cell and 60 degrees from the normal direction of the liquid crystal cell. The luminance 1 was measured with a luminance meter (spectral radiance meter CS-1000: manufactured by Minolta Co., Ltd.) installed at a distance of 1 m in the direction of.
Next, each liquid crystal display device having a polarizing plate bonded on the same Schaukasten as described above was placed, and the luminance 2 was measured in the same manner as described above.

(3) Color shift during black display (front)
Place the liquid crystal cell with the polarizing plate pasted on the Schaukasten set in the dark room, and observe the liquid crystal cell from the place 1m away in the normal direction. It was evaluated as follows. The intensity of the color shift was in accordance with the following criteria.
○: Specific color is not visible ○ △: Specific color is slightly visible
Δ: A specific color can be seen a little.
X: A specific color can be clearly seen.

(4) Color shift during black display (diagonal)
A liquid crystal cell is placed on a Schaukasten set in a dark room with a polarizing plate attached, and is oriented 45 degrees leftward with respect to the rubbing direction of the liquid crystal cell and 60 degrees from the normal direction of the liquid crystal cell. The color shift at the time of black display was evaluated based on the same criteria as the above (3) from a distance of 1 m in the direction of.

From the results in Table 3, the following is clear.
The VA mode liquid crystal display device using the negative A plate of the present invention having a slow axis in the longitudinal direction and Rth (550) / Re (550) of −0.5 is excellent in both light leakage and color shift. there were.

[Example 6]
As a material having a negative intrinsic birefringence value, a norbornene-based ring-opening copolymer having a fluorene skeleton was used.
Spiro [fluorene-9,8′-tricyclo [4.3.0.1 ^2.5 ] represented by the following formula (A) according to the synthesis method described in JP-A-2005-36201 [0161] to [0164]. ] [3] Decene] (exo form) was synthesized.

3.67 g of the above monomer, 8-methoxycarbonyl-8-methyltetracyclo represented by the following formula (C) [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene (3.0 g), molecular weight regulator 1-hexene (0.20 g) and toluene (13.4 g) were charged into a nitrogen-substituted reaction vessel and heated to 80 ° C. To this, 0.068 mL of a toluene solution of triethylaluminum (0.6 mol / L) and 0.21 mL of a toluene solution of methanol-modified WCl ₆ (0.025 mol / L) are added and reacted at 80 ° C. for 0.5 hour. Thus, a ring-opening copolymer solution was obtained. The obtained ring-opening copolymer had a weight average molecular weight (Mw) of 28.0 × 10 ⁴ and a molecular weight distribution (Mw / Mn) of 6.08.

Next, the obtained ring-opening copolymer solution was put in an autoclave, and 300 g of toluene was further added. The hydrogenation catalyst RuHCl (CO) [P (C ₆ H ₅ )] ₃ is added at 2500 ppm with respect to the monomer charge, the hydrogen gas pressure is 9-10 MPa, and the reaction is carried out at 160-165 ° C. for 4 hours. went. After completion of the reaction, a hydrogenated product was obtained by precipitation in a large amount of methanol solution. The obtained hydrogenated ring-opening copolymer has a weight average molecular weight (Mw) = 26.9 × 10 ⁴ , a molecular weight distribution (Mw / Mn) = 4.37, an intrinsic viscosity [η] = 1.07, The glass transition temperature (Tg) was 188.8 ° C.

  The copolymer obtained above was dissolved in methylene chloride to prepare a dope solution having a solid content concentration of 18% by mass. A cast film was prepared from this dope solution, and a long unstretched film 120 having a thickness of 60 μm was obtained. The amount of residual solvent in this unstretched film was 0.2 mass% or less.

  A step of stretching the long unstretched film 120 obtained above using a tenter having a structure that narrows the continuous long film while the lengthwise interval of the tenter clip is held and conveyed. The film is sent to a stretching device (trade name “FITZ” manufactured by Ichikin Kogyo Co., Ltd.), and the film temperature is set to 199 ° C. After 30 seconds, the film starts to be stretched and then stretched 0.85 times in the longitudinal direction of the film. The film was subjected to relaxation shrinkage (shrinkage rate 15%), and the width direction was stretched 1.30 times with a tenter clip (stretching rate 30%) to obtain a retardation film 121 having a film thickness of 53 μm after stretching.

  Re and Rth at a wavelength of 550 nm of the obtained retardation film 121 were measured by KOBRA 21ADH (manufactured by Oji Scientific Instruments) according to the method described above. The in-plane retardation Re (550) is 120 nm, the thickness direction retardation Rth (550) is −60 nm, the in-plane slow axis is a direction parallel to the longitudinal direction, and the variation is ± 0.05 °. The residual volatile component content was 0.01% by mass or less. That is, the retardation film 121 was a negative A plate having an in-plane slow axis parallel to the longitudinal direction.

Next, with respect to the film shown in Example 1, Reference Example 1 in which the shrinkage rate is less than the lower limit of the formula (Z) and Reference Example 2 exceeding the upper limit are shown.
[Reference Example 1]
A film similar to Example 1 except that it was relaxed and contracted 0.95 times in the longitudinal direction (shrinkage rate 5%) and stretched 1.40 times in the width direction (stretching rate 40%). As a result, Re (550) = 90 nm, Rth (550) = − 55 nm, and Rth (550) / Re (550) = − 0.61 and the characteristics of the negative A plate were not satisfied.

  A film similar to Example 1 except that it was relaxed and contracted 0.74 times in the longitudinal direction (shrinkage ratio 26%) and stretched 1.40 times in the width direction (stretching ratio 40%). As a result, a film satisfying the characteristics of the negative A plate was obtained, but some wrinkles were generated. Although this wrinkle could be reduced by adjusting the conveyance speed, the productivity was lowered by lowering the conveyance speed.

It is a schematic diagram which shows the structure of one Embodiment of the liquid crystal display device of this invention. It is a schematic diagram which shows the structure of the comparison form of the liquid crystal display device of this invention. It is a schematic diagram which shows the structure of other embodiment of the liquid crystal display device of this invention. It is a schematic diagram which shows the structure of other embodiment of the liquid crystal display device of this invention. It is a schematic diagram which shows the structure of other embodiment of the liquid crystal display device of this invention. It is a schematic diagram which shows the structure of other embodiment of the liquid crystal display device of this invention. It is a schematic diagram which shows the structure of other embodiment of the liquid crystal display device of this invention.

Explanation of symbols

1 First polarizing film protective film (outside)
2 First polarizing film absorption axis direction 3 First polarizing film 4 First polarizing film protective film (cell side)
5 Slow axis direction of liquid crystal cell during black display 6, 6 ′ Liquid crystal cell 7 Second polarizing film protective film (cell side)
8 Second polarizing film 9 Second polarizing film absorption axis direction 10 Second polarizing film protective film (outside)
11 First retardation film (negative A plate of the present invention)
11 ′ first retardation film (negative A plate outside the scope of the present invention)
12 Slow axis direction of the first retardation film 13 Second retardation film 14 Slow axis direction of the second retardation film

Claims (18)

The film includes a film composed of one or more layers containing a material having a negative intrinsic birefringence value, and includes stretching in a width direction perpendicular to the transport direction and contracting in the transport direction. Manufacturing method of negative A plate. The method according to claim 1, wherein the film is stretched in the width direction while being gripped and transported by a tenter clip, and the film is contracted by narrowing an interval between the tenter clips along the transport direction. 3. The method according to claim 1, wherein the following mathematical formula (Z) is satisfied when the stretching ratio in the width direction is X% and the shrinkage ratio in the transport direction is Y%.

The method according to any one of claims 1 to 3, wherein the material having a negative intrinsic birefringence value is a vinyl aromatic polymer. The method according to claim 4, wherein the vinyl aromatic polymer is a copolymer of styrene and / or a styrene derivative and maleic anhydride. The method according to claim 1, wherein the material having a negative intrinsic birefringence is a polycarbonate having a fluorene skeleton. The method according to claim 1, wherein a negative A-plate having a width of 0.2 to 3 m and a length of 20 to 10,000 m is obtained. While transporting a film composed of one layer or two or more layers containing a material having a negative intrinsic birefringence value, the film is stretched in the width direction orthogonal to the transport direction, and contracted in the transport direction, And a lamination step of laminating the negative A plate and the polarizer in a long state. The negative A plate produced by the method of any one of Claims 1-7. It has at least one layer containing a material having a negative intrinsic birefringence value, an in-plane slow axis is parallel to the longitudinal direction, and satisfies the following formulas (1) and (2): Long negative A plate:
Formula (1): 50 nm ≦ Re (550) ≦ 300 nm
Formula (2): -0.6 <= Rth (550) / Re (550) <=-0.4. The negative A plate according to claim 10, further satisfying the following formula (3):
Formula (3): −0.55 ≦ Rth (550) / Re (550) ≦ −0.45. The negative A plate according to claim 10, further comprising a transparent polymer layer. The negative A plate according to any one of claims 10 to 12, which is cut into a size that can be incorporated into a liquid crystal display device. A polarizing plate having at least the negative A plate according to claim 10 and a polarizer. The polarizing plate according to claim 14, wherein only a substantially isotropic adhesive layer and / or a substantially isotropic protective film is included between the negative A plate and the polarizer. A pair of first and second polarizers arranged with their absorption axes orthogonal to each other, a pair of substrates, and liquid crystal molecules sandwiched between the pair of substrates substantially with respect to the substrate during black display A liquid crystal display device comprising: a liquid crystal cell having a liquid crystal layer aligned in parallel; and the negative A plate according to claim 13 between the first polarizer and the liquid crystal cell.
A liquid crystal display device, wherein a slow axis of the negative A plate and a major axis direction of liquid crystal molecules during black display of the liquid crystal layer are substantially parallel or orthogonal. The isotropic adhesive layer and / or the substantially isotropic protective film only is included between the second polarizer and the liquid crystal cell. Liquid crystal display device. The pair of first and second polarizers arranged with their absorption axes orthogonal to each other, the pair of substrates, and the liquid crystal molecules sandwiched between the pair of substrates substantially with respect to the substrate during black display A liquid crystal display device comprising: a liquid crystal cell having a vertically aligned liquid crystal layer; and the negative A plate according to claim 13 between the first polarizer and the liquid crystal cell.

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