WO2011064826A1

WO2011064826A1 - Va-type liquid crystal display apparatus

Info

Publication number: WO2011064826A1
Application number: PCT/JP2009/006460
Authority: WO
Inventors: 石黒誠
Original assignee: 富士フイルム株式会社
Priority date: 2009-11-30
Filing date: 2009-11-30
Publication date: 2011-06-03

Abstract

Provided is a VA-type liquid crystal display apparatus having a high front contrast. The VA-type liquid crystal display apparatus comprises a front side polarizer (14), a rear side polarizer (12), a VA-type liquid crystal cell (LC) arranged between the front side polarizer and the rear side polarizer, and a first phase difference area (16) which is formed of one or more phase difference layers arranged between the rear side polarizer and the VA-type liquid crystal cell. The first phase difference area satisfies 0 nm ≤ Re(590) ≤ 10 nm and |Rth(590)| ≤ 25 nm, wherein Re(λ) represents the in-plane retardation (nm) at a wavelength of λ nm, and Rth(λ) represents the retardation (nm) in the thickness direction at a wavelength of λ nm.

Description

VA liquid crystal display device

The present invention relates to a VA (Vertically Aligned) liquid crystal display device with improved front contrast.

In recent years, liquid crystal display devices have become increasingly high contrast (CR). In particular, the VA liquid crystal display device has an advantage that the CR in the normal direction (hereinafter referred to as “front CR”) is higher than other modes, and various research and developments have been conducted to further improve the advantage. It has been broken. As a result, in the past six years, the front CR of the VA liquid crystal display device has increased from about 400 to about 8000, about 20 times higher.

On the other hand, for a liquid crystal display device, it is important that not only the front CR is high but also the CR in the oblique direction (hereinafter sometimes referred to as “viewing angle CR”) is high. For VA liquid crystal display devices, various proposals have been made to adopt a retardation film as a technique for reducing light leakage that occurs in an oblique direction during black display (for example, Patent Document 1). In general, a phase difference film is arranged on the front side and the rear side centering on the liquid crystal cell, and the optical retardation is achieved by sharing the phase difference necessary for optical compensation between the two retardation films. ing. Two methods are usually used for the combination of optical compensation. One method is a method in which retardation films are equally allocated to the retardation films respectively arranged on the front side and the rear side, and there is an advantage that a single film can be used. The other method is a method in which a large phase difference is shared by the phase difference film disposed on one side, and is advantageous in terms of cost because optical compensation can be performed in combination with an inexpensive film. In the latter method, it has been practically common to share a large retardation with the retardation film disposed on the rear side. One reason is manufacturing cost. Regarding this reason, in Patent Document 2, when the cellulose acylate film of the present invention is used only for the protective film (between the liquid crystal cell and the polarizing film) of one polarizing plate, Either the observation side) or the lower side polarizing plate (backlight side) may be used, and there is no functional problem, but there is a need to provide a functional film on the observation side (upper side) when used as an upper polarizing plate. Since there is a possibility that the production yield will be reduced, it is considered that the use as a lower polarizing plate is high, and it is considered to be a more preferable embodiment. The second reason is that it is preferable to dispose a film having a larger phase difference on the rear side in terms of impact resistance and environmental resistance such as temperature change and humidity change.
Conventionally, no study has been made on the relationship between the optical characteristics of the retardation film (retardation film) used for improving the viewing angle contrast and the front CR.

JP 2006-184640 A [0265] column of JP-A-2006-241293

In a liquid crystal display device with a high CR, it is difficult to achieve a higher contrast with the method proposed based on the conventional factors for reducing the CR. As a result of intensive studies by the present inventors, in the VA type liquid crystal display device, the retardation of the retardation layer existing between the rear side polarizer and the liquid crystal cell, which has not been considered to affect the front CR, has been obtained. It has been found that this is one of the causes of lowering the front CR.

An object of the present invention is to provide a VA liquid crystal display device with high front contrast.

Means for solving the above problems are as follows.
[1] Front-side polarizer, rear-side polarizer, VA-type liquid crystal cell disposed between the front-side polarizer and the rear-side polarizer, and between the rear-side polarizer and the VA-type liquid crystal cell Have a first retardation region composed of one or two or more retardation layers, and the first retardation region has the following formula:
0 nm ≦ Re (590) ≦ 10 nm and | Rth (590) | ≦ 25 nm
VA type liquid crystal display device satisfying the following:
However, Re (λ) means in-plane retardation (nm) at the wavelength λnm, and Rth (λ) means retardation in the thickness direction (nm) at the wavelength λnm.
[2] The VA type liquid crystal cell has a front side substrate and a rear side substrate, and a ratio of a member contrast (CR _f ) of the front side substrate to a member contrast (CR _r ) of the rear side substrate (CR _f / (CR _r ) is 3 or more, VA type liquid crystal display device according to [1]. [3] Between the front-side polarizer and the VA-type liquid crystal cell, there is a second retardation region composed of one or two or more retardation layers, and the second retardation region is Following formula:
30 nm ≦ Re (590) ≦ 90 nm and 170 nm ≦ Rth (590) ≦ 300 nm
The VA liquid crystal display device according to [1] or [2], wherein:
[4] The first and second retardation regions are represented by the following formula:
Δnd (590) −70 ≦ Rth ₁ (590) + Rth ₂ (590) ≦ Δnd (590) −10
[3] VA liquid crystal display device characterized by satisfying:
Where d is the thickness (nm) of the liquid crystal layer of the VA type liquid crystal cell, Δn (λ) is the refractive index anisotropy at the wavelength λ of the liquid crystal layer of the VA type liquid crystal cell, and Δnd (λ) is Δn Rth ₁ (λ) is retardation in the thickness direction of the first retardation region at wavelength λ (nm), and Rth ₂ (λ) is the second at wavelength λ. Means retardation (nm) in the thickness direction of the retardation region.
[5] The VA liquid crystal display device according to any one of [1] to [4], wherein the first retardation region is made of a cellulose acylate film or includes a cellulose acylate film.
[6] A compound in which the cellulose acylate film reduces the retardation Rth in the thickness direction is represented by the following formulas (I) and (II):
(I) (Rth [A] −Rth [0]) / A ≦ −1.0
(II) 0.01 ≦ A ≦ 30
(Rth [A]: Rth (nm) of a film containing A% of a compound that lowers Rth, Rth [0]: Rth (nm) of a film not containing a compound that lowers Rth, and A: (5) The VA liquid crystal display device according to [5], wherein at least one compound is contained within a range satisfying the mass (%) of the compound when the mass is 100.
[7] The cellulose acylate film is a cellulose acylate having an acyl substitution degree of 2.85 to 3.00, a cellulose acylate having at least one compound that reduces in-plane retardation Re and thickness direction retardation Rth. The VA liquid crystal display device according to [5] or [6], which is contained in an amount of 0.01 to 30% by mass with respect to the rate solid content.
[8] The cellulose acylate film comprises at least one compound that lowers | Re (400) -Re (700) | and | Rth (400) -Rth (700) | The VA type liquid crystal display device according to any one of [5] to [7], wherein the VA type liquid crystal display device is contained in an amount of 0.01 to 30% by mass based on the total amount.
[9] The VA liquid crystal display device according to any one of [1] to [8], wherein the first retardation region is made of an acrylic polymer film or includes an acrylic polymer film.
[10] The first retardation region comprises an acrylic polymer film containing an acrylic polymer containing at least one unit selected from a lactone ring unit, a maleic anhydride unit, and a glutaric anhydride unit; [9] The VA type liquid crystal display device having the acrylic polymer film.
[11] The VA liquid crystal display device according to any one of [3] to [10], wherein the second retardation region is made of a cellulose acylate film or includes a cellulose acylate film.
[12] The VA liquid crystal display device according to any one of [3] to [10], wherein the second retardation region is made of a cyclic olefin polymer film or includes a cyclic olefin polymer film.
[13] The VA liquid crystal display device according to any one of [1] to [12], wherein the front contrast is 1500 or more.
[14] The VA liquid crystal display device according to any one of [1] to [13], which includes a backlight unit that sequentially emits independent three primary color lights and is driven by a field sequential driving method.

According to the present invention, a VA liquid crystal display device with high front contrast can be provided.

It is a cross-sectional schematic diagram of an example of the VA-type liquid crystal display device of the present invention. It is the schematic diagram used in order to demonstrate the effect | action of this invention.

Hereinafter, the present invention will be described in detail. In the present specification, a numerical range expressed using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.
First, terms used in this specification will be described.
(Retardation, Re and Rth)
In the present specification, Re (λ) and Rth (λ) represent in-plane retardation (nm) and retardation in the thickness direction (nm) at 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). The standard wavelength of KOBRA is 590 nm.
When a sample such as a film to be measured is represented by a uniaxial or biaxial refractive index ellipsoid, Rth (λ) is calculated by the following method.
Rth (λ) is the Re (λ), and the in-plane slow axis (determined by KOBRA 21ADH or WR) is the tilt axis (rotation axis). The light is incident at a wavelength of λ nm in 10 degree steps 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 calculated by KOBRA 21ADH or WR after changing its sign to negative.
In addition, the retardation value is measured from the two inclined directions, with the slow axis as the tilt axis (rotation axis) (in the case where there is no slow axis, the arbitrary direction in the film plane is the rotation axis), Rth can also be calculated from the following formula (X) and formula (XI) based on the value, the assumed value of the average refractive index, and the input film thickness value.

Note:
The above Re (θ) represents a retardation value in a direction inclined by an angle θ from the normal direction. In the formula, 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, and nz represents the refractive index in the direction orthogonal to nx and ny. . d represents a film thickness.

In the case where the film to be measured cannot be expressed by a uniaxial or biaxial refractive index ellipsoid, that is, a film having no so-called optical axis, Rth (λ) is calculated by the following method.
Rth (λ) is from −50 degrees to +50 degrees with respect to the normal direction of the film, with Re (λ) as the slow axis (indicated by KOBRA 21ADH or WR) in the plane and the tilt axis (rotation axis). The light of wavelength λ nm is incident from each inclined direction in 10 degree steps and measured at 11 points. Based on the measured retardation value, the assumed average refractive index, and the input film thickness value, KOBRA 21ADH or WR is calculated.
In the above measurement, as the assumed value of the average refractive index, values in the polymer handbook (John Wiley & Sons, Inc.) and catalogs of various optical films can be used. Those whose average refractive index is not known can be measured with an Abbe refractometer. Examples of the average refractive index values of main optical films are given below:
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 value of the average refractive index and the film thickness. Nz = (nx−nz) / (nx−ny) is further calculated from the calculated nx, ny, and nz.

In this specification, “slow axis” of a retardation film or the like means a direction in which the refractive index is maximum. The “visible light region” means 380 nm to 780 nm. Moreover, in this specification, when there is no special mention about a measurement wavelength, a measurement wavelength is 590 nm. The wavelength of 590 nm is a wavelength generally used for management of physical properties of a film in the technical field industry to which the present invention belongs.
Further, in this specification, numerical values, numerical ranges, and qualitative expressions (for example, expressions of “equivalent”, “equal”, etc.) indicating optical characteristics of each member such as a retardation region, a retardation film, and a liquid crystal layer Is interpreted to indicate numerical values, numerical ranges, and properties including generally allowable errors for liquid crystal display devices and members used therefor.

In the present specification, the retardation film means a self-supporting film disposed between the liquid crystal cell and the polarizer (regardless of the size of the retardation). The retardation film is synonymous with the retardation film. The retardation region is a general term for a retardation film of one layer or two or more layers disposed between a liquid crystal cell and a polarizer.
In this specification, “front side” means the display surface side, and “rear side” means the backlight side. In this specification, “front” means a normal direction with respect to the display surface, and “front contrast (CR)” is calculated from white luminance and black luminance measured in the normal direction of the display surface. Contrast.

The present invention provides the following formula between the VA liquid crystal cell and the rear polarizer:
0 nm ≦ Re (590) ≦ 10 nm and | Rth (590) | ≦ 25 nm
The present invention relates to a VA liquid crystal display device characterized by having a first retardation region that satisfies the above.
2. Description of the Related Art Conventionally, a backlight that emits light having directivity is used as a light source of a liquid crystal display device and disposed on the rear side. Light obliquely incident on the liquid crystal display device from the backlight is scattered by the liquid crystal layer and the color filter in the liquid crystal cell, and the components scattered in the front direction contribute to lowering the front CR. As a result of investigations by the present inventors, it has been found that when the light incident on the rear side polarizer from the backlight passes through the phase difference region before entering the liquid crystal cell, the front CR is significantly reduced. The reason is as follows.
(I) The linearly polarized light obliquely incident from the backlight and passed through the rear side polarizer is elliptically polarized by Re and / or Rth in the phase difference region when passing through the phase difference region before entering the liquid crystal cell. Thereafter, the light is scattered to the front by the liquid crystal layer and the color filter layer in the liquid crystal cell. Among the light scattered in the front, the component in the absorption axis direction of the front side polarizer (hereinafter sometimes referred to as “A component”) is absorbed by the polarizer, but the component in the transmission axis direction of the front side polarizer. (Hereinafter sometimes referred to as “B component”) passes through the polarizer. This B component causes the front CR to decrease. If the B component is reduced, the front contrast can be improved. From this point of view, it is preferable that the Rth of the retardation region disposed between the rear-side polarizer and the liquid crystal cell is as small as possible.
Also,
(Ii) The retardation film constituting the retardation region has an optical axis distribution in production, and this causes an axial shift when being bonded to the polarizer. Since the axial shift promotes the elliptical polarization of light from the backlight, the front contrast can be improved by reducing the axial shift. From this point of view, the smaller the Re of the phase difference region disposed between the rear-side polarizer and the liquid crystal cell, the better.

As a result of further investigation based on the findings of (i) and (ii) above, the first retardation region between the rear-side polarizer and the liquid crystal cell has the following formula: 0 nm ≦ Re (590) ≦ 10 nm, and | Rth (590) | ≦ 25 nm
By satisfying the above, it was found that a high front CR VA liquid crystal display device was obtained, and the present invention was completed. That is, according to the present invention, the above configuration can provide a VA liquid crystal display device that achieves high front contrast. In the present invention, since only the low Re and low Rth retardation films are disposed in the retardation region between the rear side polarizer and the liquid crystal cell, the polarizer is deformed by heat from the backlight. Even when stress is applied to the retardation film, the change in optical anisotropy of the retardation film that originally has low Re and low Rth is negligible. As a result, light leakage that occurs at the four corners of the screen, which is conventionally observed in a VA liquid crystal display device, can be reduced, which is a so-called corner non-uniformity failure that degrades display quality.
Furthermore, in the aspect in which the second retardation region between the front-side polarizer and the liquid crystal cell exhibits predetermined optical characteristics, the liquid crystal display device has also achieved improved oblique CR and reduced color shift during black display. Can be provided.

FIG. 1 shows a schematic cross-sectional view of an example of the VA liquid crystal display device of the present invention. In the drawing, the relative relationship between the thicknesses of the respective layers does not necessarily coincide with the relative relationship between the thicknesses of the respective layers of the actual liquid crystal display device.
The VA type liquid crystal display device shown in FIG. 1 includes a VA type liquid crystal cell LC, and a rear side polarizing plate PL1 and a front side polarizing plate PL2 sandwiching the VA type liquid crystal cell LC. A backlight 10 is arranged on the outer side of the rear side polarizing plate PL1, and light from the backlight 10 is configured to enter the rear side polarizing plate PL1, the liquid crystal cell LC, and the front side polarizing plate PL2 in this order. ing. The liquid crystal cell LC is a VA mode liquid crystal cell and has homeotropic alignment when displaying black. The liquid crystal cell LC is configured by making an upper substrate 26 and a lower substrate 24 made of glass or the like face each other, and has an alignment film (not shown) and an electrode layer (not shown) on the substrate. Further, a color filter layer (not shown) is provided on the front substrate.

The rear side polarizing plate PL1 has the polarizer 12 and the first retardation film 16 and the outer protective film 20 on the surface thereof, respectively, and the front side polarizing plate PL2 has the polarizer 14 and the first surface on the surface thereof. 2 retardation films 18 and an outer protective film 22. The

polarizers

12 and 14 are arranged with their absorption axes orthogonal to each other. The first retardation film disposed between the polarizer 12 of the rear-side polarizing plate PL1 and the liquid crystal cell LC satisfies the following conditions: 0 nm ≦ Re (590) ≦ 10 nm and | Rth (590) | ≦ 25 nm It is a phase difference film. As long as this characteristic is satisfied, a plurality of retardation films may be present. For example, a protective film for the polarizer 12 may be separately disposed between the first retardation film 16 and the polarizer 12, but the total retardation of the first retardation film 16 and the protective film. Satisfies 0 nm ≦ Re (590) ≦ 10 nm and | Rth (590) | ≦ 25 nm. That is, a plurality of retardation films may exist between the polarizer 12 and the liquid crystal cell LC, but the total retardation of the plurality of sheets satisfies the above characteristics. Since the retardation film disposed between the polarizer 12 and the liquid crystal cell LC satisfies the above characteristics, in the VA liquid crystal display device shown in FIG. 1, oblique incident light from the backlight 10 is converted into the liquid crystal cell LC. It is possible to suppress the elliptical polarization before entering the beam. As a result, a decrease in contrast due to the reasons (i) and (ii) can be reduced, and a high front CR can be achieved.

As a result of intensive studies by the inventor, the effect of the present invention is that the member contrast CR _f of the front side substrate (including the substrate 26 and all members formed on the substrate in FIG. 1) of the VA liquid crystal cell is It has been found that this is particularly noticeable in a mode higher than the member contrast (CR _r ) of the rear side substrate (including the substrate 24 and all members formed on the substrate in FIG. 1). Further, the ratio of the member contrast CR _f of the front side substrate to the member contrast (CR _r ) of the rear side substrate (CR _f / CR _r ) is 3 or more, that is, in the aspect of 3 ≦ CR _f / CR _r . It turned out that an effect becomes remarkable. Here, when the VA liquid crystal cell (LC in FIG. 1) is disassembled into two substrates (

substrates

24 and 26 in FIG. 1), the front substrate (substrate 26 in FIG. 1) and the substrate The generic name of the members formed on the substrate is referred to as a front substrate, and the generic term of the rear substrate (substrate 24 in FIG. 1) and the members formed on the substrate is referred to as a rear substrate. Examples of the member include various members such as a color filter, a black matrix, an array member (such as a TFT array), a protrusion on the substrate, a common electrode, and a slit. That is, the member contrast between the rear side substrate and the front side substrate of the liquid crystal cell refers to the total contrast of each substrate and various members formed on each substrate. Details of the measurement method are described in Examples described later.

As a result of intensive studies by the inventor, it has been found that the retardation of the first retardation region between the rear-side polarizer and the liquid crystal cell greatly affects the front CR of the liquid crystal display device. This is because optical phenomena such as scattering and diffraction occur in each member of the liquid crystal cell (for example, liquid crystal layer, color filter, black matrix, array member, protrusion formed on the substrate, common electrode member, slit member, etc.). This is because these optical phenomena have polarization dependency. Details will be described below.
In general, in a VA liquid crystal display device, the liquid crystal layer is in a vertically aligned state during black display, and thus linearly polarized light that passes through the rear polarizer and proceeds in the normal direction passes through the liquid crystal layer. However, the polarization state does not change, and in principle, it is absorbed by the absorption axis of the front polarizer. That is, in principle, it can be said that there is no light leakage in the normal direction during black display. However, the front transmittance at the time of black display of the VA liquid crystal display device is not zero. One reason for this is that liquid crystal molecules in the liquid crystal layer are fluctuating, and light incident on the liquid crystal layer is known to be scattered to some extent by the fluctuation. As the light incident on the liquid crystal layer completely contains only the linearly polarized light component absorbed by the absorption axis of the front-side polarizer, the influence increases and the front light leakage tends to increase. That is, as the phase difference of the phase difference region arranged on the rear side is larger and converted into elliptically polarized light having a higher elliptical polarization rate, light leakage on the front due to this fluctuation can be reduced.

However, as a result of investigation by the present inventor, it was found that in addition to the fluctuation of the liquid crystal molecules in the liquid crystal layer, the phase difference in the retardation region between the rear-side polarizer and the liquid crystal layer is also responsible for this. When directional light from the backlight passes through the rear polarizer and enters the phase difference region from an oblique direction, linearly polarized light is converted into elliptically polarized light by the phase difference. The elliptically polarized light is diffracted and scattered by the array member in the liquid crystal cell and the color filter layer, and at least a part of the light becomes light traveling in the front direction. Since the elliptically polarized light includes a linearly polarized light component that cannot be blocked by the absorption axis of the front-side polarizer, light leaks in the front direction even during black display, causing a reduction in front CR. The optical phenomenon caused by passing through the array member or the color filter layer is, for example, that the surface of the array member or the color filter layer is not completely smooth and has a certain degree of unevenness, or a scattering factor or the like in the member. By being contained. The influence of the optical phenomenon generated by passing through the array member and the color filter layer on the light leakage in the front direction is larger than the influence of the liquid crystal molecules in the liquid crystal layer described above.

Furthermore, as a result of intensive studies by the inventor, optical phenomena (diffraction and scattering, etc.) received when light that has become elliptically polarized light by passing through the phase difference region passes through a predetermined member in the liquid crystal cell, It has been found that the aspect affecting the light leakage in the front direction differs depending on whether the light passes through the member before entering the liquid crystal layer or passes through the member after passing through the liquid crystal layer. In FIG. 1, for example, as shown in FIG. 2A, if an array member is arranged on the inner surface of the rear substrate 24 and a color filter is arranged on the inner surface of the front substrate 26, the light is The light passes through the array member before entering the liquid crystal layer, and passes through the color filter after passing through the liquid crystal layer.
In a member that passes light before entering the liquid crystal layer (for example, an array member), the elliptical polarization rate of the incident light is determined by the phase difference of the rear-side phase difference region (first phase difference region) that passes therethrough. . On the other hand, a member (for example, a color filter) that passes after entering the liquid crystal layer is determined by the phase difference of the liquid crystal layer in addition to the phase difference of the rear side phase difference region. Here, in the case of a VA liquid crystal display device, generally, Δnd (590) of the liquid crystal layer (d is the thickness (nm) of the liquid crystal layer, and Δn (λ) is the refractive index anisotropy at the wavelength λ of the liquid crystal layer. , Δnd (λ) is the product of Δn (λ) and d.) Is set to about 280 to 350 nm. Even if the phase difference in the rear side phase difference region is set so that light leakage of the array member is reduced, the ellipticity increases conversely when passing through the liquid crystal. As the phase difference in the rear phase difference region is larger, the ellipticity of incident polarized light is smaller. Therefore, the light is incident before passing through the liquid crystal layer, or the light is incident after passing through the liquid crystal layer. Accordingly, as a result of setting the phase difference in the rear side phase difference region to be low, the effect of the member on the light leakage in the front direction is reversed.
FIG. 2B summarizes the phase difference in the rear side phase difference region, the tendency of the influence on the light leakage in the front direction by passing through each member, and the strength of the influence. In FIG. 2B, “↑” indicates an effect of increasing the front CR as compared to the case where the rear phase difference region has a high retardation, and “↓” indicates an effect of decreasing the front CR. The number of arrows is a measure of the strength of the action, and the greater the number, the stronger the action.

As shown in FIG. 2B, in the aspect of the VA liquid crystal display device in which the color filter is arranged on the front side substrate and the array member is arranged on the rear side substrate, if the phase difference in the rear side retardation region is lowered, the rear side The light leakage in the front direction caused by the optical phenomenon by the array member arranged on the substrate acts in the direction to be reduced, while the light leakage in the front direction caused by the optical phenomenon by the color filter layer arranged on the front side substrate. Acts in an increasing direction, i.e., there is a relationship in which both actions cancel out.

For example, in a liquid crystal cell in which members that cause a decrease in contrast are similarly arranged on both the rear side substrate and the front side substrate, even if the first retardation region on the rear side has low retardation, The front CR by the member (for example, the CF member in FIG. 2B) arranged on the front substrate is the effect of increasing the front CR by the member (for example, the array member in FIG. 2B) disposed on the rear side substrate. There is a case where it is slightly canceled by the action of lowering the CR. That is, the feature of the present invention that the first retardation region on the rear side has a low retardation is particularly effective in an aspect in which many members that cause a decrease in contrast are present on the rear substrate. You can say.

Note that the influence of the retardation of the first retardation region on the rear side on the front CR is almost negligible in a low front CR liquid crystal display device. However, this influence cannot be ignored in order to further improve the front CR of a liquid crystal display device with a high front CR (for example, the front CR is 1500 or more) that has been provided in recent years. The present invention is particularly useful for further improving the front CR for liquid crystal display devices having a front CR of 1500 or more.

In FIG. 2, as an example, a normal liquid crystal cell configuration in which a color filter (CF) is provided on the inner surface of the front substrate 26 and an array member is provided on the inner surface of the rear substrate 24 is illustrated. In the apparatus, the positions of the CF and the array member are arbitrary. For example, an embodiment in which the CF is arranged on the rear substrate side having the array member, such as a color filter on array (COA), is also included in the present invention. Further, if the array member is disposed on the front side substrate 26 side, the operation of the array member is the same as the CF member in FIG. 2B, and the CF is disposed on the rear side substrate 24 side. If so, the operation of the CF member is the same as that of the array member of FIG. The same applies to other members not shown (for example, black matrix). If the members are arranged on the front substrate 26 side, the function of the array member is as shown in FIG. If the member is the same as the CF member and the member is arranged on the rear substrate 24 side, the operation of the member is the same as that of the array member in FIG.

As described above, the ratio (CR _f / CR _r ) of the member contrast CR _f of the front substrate (substrate 26 in FIG. 1) to the member contrast (CR _r ) of the rear substrate (substrate 24 in FIG. 1) is 3 or more, That is, it was found that the effect of the present invention becomes remarkable in an aspect satisfying 3 ≦ CR _f / CR _r . As an example of a liquid crystal cell that satisfies this relationship, for example, there is a liquid crystal cell in which the rear substrate is a COA substrate. Regarding COA, there are detailed descriptions in JP-A-2005-99499 and JP-A-2005-258004.

As described above, the dependency of incident light on the incident polarization state of light leakage at the time of black display due to the optical phenomenon in the CF, black matrix, and array member shows the same tendency, but the contribution of the black matrix is relatively small. Therefore, the position of the black matrix in the liquid crystal display device of the COA in which the CF is arranged on the rear substrate side having the array member may be located in the liquid crystal cell, and may be located between the rear polarizer and the liquid crystal layer. preferable.

Examples of the liquid crystal cell that satisfies 3 ≦ CR _f / CR _r include a liquid crystal cell that does not have a color filter and a liquid crystal cell that does not have a color filter and is field sequential drive. The field sequential drive liquid crystal cell is described in detail in Japanese Patent Application Laid-Open No. 2009-42446, Japanese Patent Application Laid-Open No. 2007-322988, Japanese Patent No. 3996178, and the like. In the field sequential drive, a backlight unit that sequentially emits independent three primary color lights is used. A backlight unit including an LED as the light source is preferable. For example, a backlight unit including an LED element that emits three colors of red, green, and blue as the light source is preferably used.

In addition, even in a normal mode liquid crystal cell in which an array member is arranged on the rear side substrate and a color filter is arranged on the front side substrate, the above condition is, of course, as long as the color filter has a high contrast. 3 ≦ CR _f / CR _r is satisfied, which is a preferred embodiment of the present invention. As an example of a high-contrast color filter, there is a color filter using a pigment having a finer particle diameter than that of a pigment used in a conventional CF. Examples of a method for producing a high-contrast color filter using a pigment include the following two methods.
(I) A method of mechanically pulverizing pigment particles using a disperser such as a sand mill, a roll mill, or a ball mill. .
(Ii) A method of adjusting fine pigment particles by dissolving the pigment in a solvent and then reprecipitating it, which is described in detail in, for example, JP-A-2009-134178.
In addition to the pigment, a method for producing a high-contrast color filter using a dye has also been proposed. JP-A-2005-173532 has a detailed description and can be referred to.
By using these high-contrast color filters, a liquid crystal cell satisfying 3 ≦ CR _f / CR _r is obtained even with a normal configuration.

In FIG. 1 again, it is preferable that the optical characteristics of the second retardation film 18 of the front polarizing plate PL2 contribute to the improvement of the contrast in the oblique direction and the reduction of the color shift during black display. . Note that Δnd (λ) of the liquid crystal layer of the VA liquid crystal cell LC is generally about 280 to 350 nm as described above. The preferred range of retardation, particularly Rth, of the second retardation film 18 varies depending on the value of Δnd (λ) of the liquid crystal layer. For the purpose of improving the oblique contrast, preferred combinations of retardation films with respect to Δnd (λ) are described in various publications, and are described in, for example, Japanese Patent Nos. be able to.
A preferable range of the optical characteristics of the second retardation region will be described later.

Note that Δnd (590) of the VA liquid crystal cell is generally about 280 to 350 nm, in order to make the transmittance during white display as high as possible. On the other hand, when Δnd (590) is 280 nm or less, white luminance slightly decreases with a decrease in Δnd (590), but the thickness d of the cell is reduced, so that a liquid crystal display device excellent in high-speed response is obtained. If the first retardation region on the rear side has a low retardation, light leakage in the front direction is reduced, and as a result, a high front CR is obtained. The feature of any liquid crystal display of any Δnd (590) It is also effective in the apparatus.

In the VA liquid crystal display device of FIG. 1, an embodiment in which the first retardation film 16 and the second retardation film 18 also function as protective films for the

polarizers

12 and 14 is shown. The invention is not limited to this embodiment. For example, a protective film for a polarizer may be separately disposed between each of the first retardation film and the second retardation film and the

polarizers

12 and 14. However, as described above, the protective film disposed between the first retardation film and the polarizer 12 is required in the first retardation region as a laminate with the first retardation film. It is necessary to satisfy the characteristics.
The rear polarizer 12 has a protective film 20 on the surface on the backlight 10 side, and further has functionalities such as an antifouling film, an anti-reflection film, an anti-glare film, and an anti-static film on the surface. Similarly, the front polarizer 14 has a protective film 22 on the display surface side surface, and further has an antifouling film, an anti-reflection film, an anti-glare film on the surface. You may have functional films, such as a film and an antistatic film.

By the way, as described above, in the case of a system in which a large phase difference is shared on one side and optical compensation is performed, a film having a large phase difference is generally arranged on the rear side, but as in the present invention. It is considered that the yield rate as a polarizing plate is improved by arranging it on the front side. The reason will be explained.
Since a film having a large retardation requires a process of stretching at a high magnification, an inexpensive film that can be produced without adding many additives to the film, so-called plain TAC = Re is 0 to 10 nm, and Rth is 30 to 80 nm. It is difficult to widen the width compared to a film having a certain triacetyl cellulose film or a small retardation film. In a normal liquid crystal display device, a horizontally long liquid crystal cell is used, and the absorption axis of the front-side polarizer is arranged in the horizontal direction (left-right direction), and the absorption axis of the rear-side polarizer is arranged in the vertical direction (up-down direction). It is common. Furthermore, in industrial production, a polarizer and a retardation film are generally bonded by roll-to-roll. Considering that the polarizing plate produced by this manufacturing method is bonded to the liquid crystal cell, it is possible to use the width direction of the polarizing plate with high efficiency by arranging a film having a large retardation on the front side, that is, The yield increases. When a retardation film having a small retardation is arranged on the rear side as in the present invention, such a film can be easily produced as a wide film, and the yield is further increased by combining with a wide polarizer. it can. As a result, the amount of polarizing plate to be discarded can be reduced.

Here, I will explain with specific numbers. In general, the width of the retardation film is approximately 1100 mm, 1300 mm, 1500 mm, 2000 mm, and 2500 mm, and the thickness of the film is approximately 25 μm, 40 μm, and 80 μm. The length of the roll around which the film is wound is approximately 2500 m and 4000 m. On the other hand, the screen size of the VA liquid crystal display device is 20 inches, 32 inches, 40 inches, 42 inches, 52 inches, 68 inches, etc., for television use. As an example, when 42 inches, which are currently shipped, are considered to be 42 inches (standard 4: 3), the screen width is 853 mm (42 inches wide 16: 9 is 930 mm), and the screen height is 640 mm (42 inches wide is 523 mm). In the conventional method in which a film having a large retardation is arranged on the rear side, for example, a retardation film having a width of 1300 mm or 1500 mm can take only one retardation film for a screen in the width direction. In this aspect, since a film having a large retardation is arranged on the front side, for example, even if the retardation film has a width of 1300 mm or 1500 mm, it suffices that the screen height can be taken in the width direction of the retardation film. The retardation film for two screens can be taken in the width direction, and productivity is nearly doubled. The size of TVs increases year by year. For example, 65 inches (standard) has a screen width of 991 mm and a screen height of 1321 mm. However, only one retardation film for a screen can be taken in the width direction. However, as in this aspect, two retardation films for a screen can be taken in the width direction in the front side arrangement. Furthermore, since the 68-inch (wide) screen has a screen width of 1505 mm and a screen height of 846 mm, a productivity almost twice as high can be expected.

The mode of the VA type liquid crystal display device of the present invention may be any mode, specifically, MVA (Multi-domain Vertical Alignment) type, PVA (Patterned Vertical Alignment) type, optical alignment type (Optical Alignment), and Any of PSA (Polymer-Sustained Alignment) may be used. Details of these modes are described in JP-A-2006-215326 and JP-T 2008-538819.

As described above, in the present invention, a high-contrast color filter may be used, but of course, a color filter included in a normal liquid crystal display device may be used. The color filter is generally a color filter in which a plurality of different colors (for example, three primary colors of red, green, and blue light, transparent, yellow, cyan, and the like) are arranged in a pixel portion of the substrate. There are various preparation methods, for example, using a coloring material (organic pigment, dye, carbon black, etc.) to prepare a colored photosensitive composition (which may be colorless) called a color resist. In general, a layer is formed by coating on a substrate, and a pattern is formed by photolithography. There are also various methods for applying the colored photosensitive composition on the substrate, for example, initially, a spin coater method is adopted, and from the viewpoint of saving liquid, a slit & spin type coater method is adopted. The slit coater method is generally adopted. Other methods include roll coating, bar coating, and die coating. In recent years, after forming a pattern called a separation wall by photolithography, a pixel color is also formed by an inkjet method. In addition, methods using a combination of a colored non-photosensitive composition and a photosensitive positive resist, a printing method, an electrodeposition method, and a film transfer method are known. The color filter used in the present invention may be produced by any method.

There are no particular restrictions on the material for forming the color filter. As the coloring material, any of dyes, organic pigments, inorganic pigments and the like can be used. Dyes have been studied because of the demand for higher contrast, but in recent years, organic pigment dispersion technology has advanced, and breakdown pigments that have been finely crushed by the salt milling method, finer pigments by the build-up method, etc. Used for contrast. Any coloring material may be used in the present invention.

Further, the effect of improving the front contrast of the present invention can be further improved by adjusting the angle profile of the light emitted from the backlight. Specifically, when a backlight having a higher light collecting property is used, the absolute value of the front contrast is increased, so that the increase in the absolute value of the front CR shown in the present invention is also increased. The light collecting index is represented by, for example, a ratio I (0 °) / I (45 °) of the outgoing light intensity I (45 °) at a polar angle of 45 degrees with respect to the outgoing light intensity I (0 °) at the front. The larger the value, the stronger the light collection. As a backlight having a high light collecting property, it is desirable to provide a prism film (prism layer) having a light collecting function between the diffusion film and the liquid crystal panel. This prism film collects the light emitted from the light exit surface of the light guide plate and diffused by the diffusion film with high efficiency on the effective display area of the liquid crystal panel. A liquid crystal display device equipped with a general direct type backlight has, for example, a color filter sandwiched between a transparent substrate and a polarizing plate at the top, a liquid crystal panel composed of a liquid crystal layer, and a backlight on the lower surface side. It has been. A brightness enhancement film (Brightness Enhancement Film: BEF), which is a registered trademark of 3M USA, is a representative example. BEF is a film in which unit prisms having a triangular cross section are periodically arranged in one direction on a film substrate, and the prism has a size (pitch) larger than the wavelength of light. BEF collects light from “off-axis” and redirects this light “on-axis” or “recycle” toward the viewer. To do. Patent documents that disclose that a brightness control member having a repetitive array structure of prisms represented by BEF is adopted for a display are disclosed in Japanese Patent Publication No. 1-37801, Japanese Patent Laid-Open No. 6-102506, Special Table. Many examples are known as exemplified in Japanese Patent Laid-Open No. 10-506500.

Also, it is desirable to use a lens array sheet in order to improve the light collecting property. The lens array sheet has a lens surface in which a plurality of unit lenses formed in a convex shape at a predetermined pitch are two-dimensionally arranged. A lens array sheet in which the opposite side of the lens surface is a flat surface and a light reflecting layer for reflecting light rays on the non-light-condensing surface region of the lens is formed on the flat surface is preferable. Further, a lenticular lens surface in which a plurality of convex cylindrical lenses formed at a predetermined pitch are arranged in parallel, and a side opposite to the lens surface is a flat surface, and the convex surface has the convex surface. A lens array sheet in which a light reflecting layer for reflecting light beams in the longitudinal direction is formed on the non-light-condensing surface region of the cylindrical lens is also preferable. Further, for example, a lenticular lens array sheet in which unit lenses composed of cylindrical curved surfaces are arranged in one plane in a plane, or a dome-shaped curved surface having a bottom surface shape such as a circle, a rectangle, or a hexagon. A lens array sheet in which unit lenses are two-dimensionally arranged in a plane can also be used. Regarding these lens array sheets, JP-A-10-241434, JP-A-2001-201611, JP-A-2007-256575, JP-A-2006-106197, JP-A-2006-208930, JP-A-2007-213035, And can be referred to in Japanese Laid-Open Patent Publication No. 2007-41172.

The present invention is also effective in a display mode in which the color reproduction range is widened by adjusting the emission light spectrum of the backlight and the transmission spectrum of the color filter. Specifically, it is desirable to use a white backlight in which a red LED, a green LED, and a blue LED are mixed and mixed as the backlight. Moreover, it is preferable that the half value width of the emitted light peak of red LED, green LED, and blue LED is small. In the case of LED, the half-value wavelength width is as small as about 20 nm as compared with CCFL, and the peak wavelength is R (red) is 610 nm or more, G (green) is 530 nm, and B (blue) is 480 nm or less. The color purity of the light source itself can be increased.

Further, it has been reported that the color reproducibility is further improved by suppressing the spectral transmittance of the color filter as small as possible except for the peak wavelength of the LED, and the NTSC ratio is 100%. For example, it is described in JP-A-2004-78102. The red color filter desirably has a small transmittance at the peak positions of the green LED and the blue LED, the green color filter desirably has a small transmittance at the peak position of the blue LED and the red LED, and the blue color filter has a red color. It is desirable that the transmittance at the peak position of the LED and the green LED is small. Specifically, both of these transmittances are desirably 0.1 or less, more preferably 0.03 or less, and still more preferably 0.01 or less. The relationship between the backlight and the color filter is described in, for example, Japanese Patent Application Laid-Open No. 2009-192661, and can be referred to.

It is also preferable to use a laser light source for the backlight in order to widen the color reproduction range. The peak wavelengths of the red, green, and blue laser light sources are preferably 430 to 480 nm, 520 to 550 nm, and 620 to 660 nm, respectively. The backlight of the laser light source is described in Japanese Patent Application Laid-Open No. 2009-14892, and can be referred to.

Hereinafter, various members used in the VA liquid crystal display device of the present invention will be described in detail.
1. First Retardation Region In the present invention, the first retardation region composed of one layer or two or more retardation layers disposed between the rear-side polarizer and the VA liquid crystal cell has the following formula:
0 nm ≦ Re (590) ≦ 10 nm and | Rth (590) | ≦ 25 nm
Satisfied. The first retardation region has the following formula:
0 nm ≦ Re (590) ≦ 5 nm and | Rth (590) | ≦ 10 nm
Preferably satisfying the following formula:
0 nm ≦ Re (590) ≦ 3 nm and | Rth (590) | ≦ 5 nm
It is more preferable to satisfy

It is preferable that the wavelength dispersion of the in-plane retardation Re in the first retardation region exhibits a so-called reverse dispersion property that the wavelength becomes larger as the wavelength becomes longer in the visible light region. That is, it is preferable that Re (450) <Re (550) <(Re (590) <) Re (630) is satisfied. The reason is that if the Re of the first retardation region is inverse wavelength dispersive, the optical wavelength is optimized at the center wavelength of about 550 nm in the visible light region, and there is a tendency to be optimized over the entire visible light region. Because there is. Ideally, the value obtained by dividing Re (λ) of the first phase difference region by the wavelength λ becomes constant. In this aspect, the transition on the Poincare sphere has a wavelength in the visible light region. This is the same regardless of the color shift problem occurring in the oblique direction.

In order to obtain a higher front CR, the haze of the retardation film constituting the first retardation region disposed on the rear side is preferably 0.5 or less, more preferably 0.3 or less, and 0.2 More preferred are:
In addition, in this specification, the measuring method of the haze of a film is as follows. A film sample of 40 mm × 80 mm is prepared and measured according to JIS K-6714 with a haze meter (NDH-2000, manufactured by Nippon Denshoku Industries Co., Ltd.) in an environment of 25 ° C. and 60% RH.

The first retardation region may be composed of one or more retardation films. There is no restriction | limiting in particular about the material. As the film satisfying the above characteristics, a cellulose acylate film and an acrylic polymer film are preferable.
Cellulose acylate film:
In the present specification, the “cellulose acylate film” refers to a film containing cellulose acylate as a main component (50% by mass or more of all components). The cellulose acylate used for producing the film is obtained by substituting the hydrogen atom of the hydroxyl group of cellulose with an acyl group. The cellulose acylate is obtained by acylating a hydroxyl group of cellulose, and the substituent can be any from an acetyl group having 2 carbon atoms to an acyl group having 22 carbon atoms. In the cellulose acylate used in the present invention, the degree of substitution of cellulose with a hydroxyl group is not particularly limited, but the degree of binding of acetic acid and / or a fatty acid having 3 to 22 carbon atoms substituted with a hydroxyl group of cellulose is measured, The degree of substitution can be obtained by calculation. As a measuring method, it can be carried out according to ASTM D-817-91.
Examples of cellulose acylate that can be used as a material for the retardation film constituting the first retardation phase difference region of the present invention are described in detail in [0019] to [0025] of JP-A-2006-184640. Cellulose acylate with the following description is included.

The degree of substitution of cellulose acylate used for producing the retardation film constituting the first retardation region is not particularly limited, but the acyl substitution degree of cellulose is preferably 2.30 to 3.00. . In order to obtain a retardation film having a low haze, the acyl substitution degree is preferably low, and the acyl substitution degree is preferably 2.30 to 2.65, and preferably 2.35 to 2.60. Is more preferable and 2.40 to 2.60 is even more preferable. On the other hand, in order for the retardation film to exhibit reverse wavelength dispersion, it is preferable that the acyl substitution degree be higher, and specifically, 2.65 to 3.00 is preferable, and 2.75 to 3.00. More preferably, it is more preferably 2.80 to 3.00.
Further, among the acyl substituents of the above-mentioned cellulose acylate, in the case of substantially consisting of at least two kinds of acetyl group / propionyl group / butanoyl group, the total degree of substitution is 2.30 to 3.00 Further, it was found that the optical anisotropy of the cellulose acylate film can be effectively reduced. The acyl substitution degree is more preferably 2.35 to 3.00, and further preferably 2.40 to 3.00.

Further, the degree of polymerization of cellulose acylate used for producing the retardation film constituting the first retardation region is 180 to 700 in terms of viscosity average polymerization degree, and in the case of cellulose acetate, 180 to 550 is more preferable. Preferably, 180 to 400 is more preferable, and 180 to 350 is particularly preferable. When the degree of polymerization is too high, the viscosity of the cellulose acylate dope solution becomes high, and film production becomes difficult due to casting. If the degree of polymerization is too low, the strength of the produced film will decrease. The average degree of polymerization can be measured by the intrinsic viscosity method of Uda et al. (Kazuo Uda, Hideo Saito, Journal of Textile Society, Vol. 18, No. 1, pp. 105-120, 1962). This is described in detail in JP-A-9-95538.

Further, the molecular weight distribution of cellulose acylate used for the production of the retardation film constituting the first retardation region was evaluated by gel permeation chromatography, and its polydispersity index Mw / Mn (Mw is a mass average) The molecular weight and Mn are preferably the number average molecular weight) and the molecular weight distribution is preferably narrow. The specific value of Mw / Mn is preferably 1.0 to 3.0, more preferably 1.0 to 2.0, and most preferably 1.0 to 1.6. preferable.

In order to produce a film that satisfies the optical properties required for the first retardation region together with one sheet or another film, various additives can be used together with cellulose acylate. Examples of additives that can be used include compounds that reduce optical anisotropy, wavelength dispersion adjusters, ultraviolet inhibitors, plasticizers, deterioration inhibitors, fine particles, optical property adjusters, and the like. In the present invention, examples of additives that can be used include various additives described in detail in [0026] to [0218] of JP-A-2006-184640. Further, the preferable range of the addition amount is the same as the preferable range described in the column.

The compound for reducing the optical anisotropy may or may not contain an aromatic group. The compound that reduces the optical anisotropy preferably has a molecular weight of 150 or more and 3000 or less, preferably 170 or more and 2000 or less, and particularly preferably 200 or more and 1000 or less. As long as these molecular weights are within the range, a specific monomer structure may be used, or an oligomer structure or a polymer structure in which a plurality of the monomer units are bonded may be used.
The compound that reduces optical anisotropy is preferably a liquid at 25 ° C. or a solid having a melting point of 25 to 250 ° C., more preferably a liquid at 25 ° C. or a melting point of 25 to 200 ° C. It is a solid. Moreover, it is preferable that the compound which reduces optical anisotropy does not volatilize in the process of dope casting of cellulose acylate film production and drying.

The amount of the compound that reduces optical anisotropy is preferably 0.01 to 30% by mass, more preferably 1 to 25% by mass, and more preferably 5 to 20% by mass based on the solid content of cellulose acylate. % Is particularly preferred. In particular, in the present invention, it is preferable to add at least one compound that reduces the optical anisotropy described above to the cellulose acylate having an acyl substitution degree of 2.85 to 3.00 in the above-mentioned addition amount.
In addition, the compound which reduces optical anisotropy may be used independently, or 2 or more types of compounds may be mixed and used by arbitrary ratios. In addition, in the solution casting method, the timing for adding the compound for reducing the optical anisotropy may be any timing during the dope preparation step, or may be added at the end of the dope preparation step.

In the present invention, the cellulose acylate film used as part or all of the first retardation region is preferably produced by a solution casting method. In this method, a film can be produced using a solution (dope) obtained by dissolving cellulose acylate in an organic solvent. When using the said additive, you may add an additive at any timing of dope preparation. For the method for producing a cellulose acylate film that can be used in the present invention, reference can be made to the descriptions in [0219] to [0224] of JP-A-2006-184640.

As the solution casting method, a lamination casting method such as a co-casting method, a sequential casting method, or a coating method can also be used. When producing by the co-casting method and the sequential casting method, first, a cellulose acylate solution (dope) for each layer is prepared. In the co-casting method (multilayer simultaneous casting), the casting dope for each layer (three layers or more) may be simultaneously pressed from another slit or the like on a casting support (band or drum). This is a casting method in which a dope is extruded from a casting giusa to be cast, and each layer is cast simultaneously, peeled off from a support at an appropriate time, and dried to form a film.
In the sequential casting method, the casting dope for the first layer is first extruded from the casting giusa on the casting support, cast, and dried on the second layer without drying or drying. The dope for casting is extruded from the casting gieser and casted, and if necessary, the dope is cast and laminated to the third layer or more, peeled off from the support at an appropriate time, and dried. This is a casting method for forming a film.
In general, the core layer film is formed into a film by a solution casting method to prepare a coating solution to be applied to the surface layer, and then applied to the film one side at a time or both sides simultaneously using an appropriate applicator. In this method, a liquid film is applied and dried to form a laminated film.

Acrylic polymer film:
The acrylic polymer film is a film mainly composed of an acrylic polymer having a repeating unit derived from at least one of (meth) acrylic acid esters. A preferred example of the acrylic polymer film is an acrylic containing at least one unit selected from a lactone ring unit, a maleic anhydride unit, and a glutaric anhydride unit together with a repeating unit derived from a (meth) acrylic ester. Based polymer. The acrylic polymer is described in detail in Japanese Patent Application Laid-Open No. 2008-9378 and can be referred to.

As the film forming method, various film forming methods can be used, and examples thereof include a solution casting method (solution casting method), a melt extrusion method, a calendar method, and a compression forming method. Of these film forming methods, the solution casting method (solution casting method) and the melt extrusion method are particularly preferable.

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

Examples of apparatuses for performing the solution casting method (solution casting method) include a drum casting machine, a band casting machine, and a spin coater.

Examples of the melt extrusion method include a T-die method and an inflation method. In this case, the film forming temperature is preferably 150 to 350 ° C., more preferably 200 to 300 ° C.

Further, the thickness of the retardation film constituting the first retardation region disposed on the rear side is preferably thinner, but in order to suppress corner unevenness, the thickness of the retardation film due to the stress applied to the retardation film is reduced. It is necessary to reduce the deformation. The thickness of the retardation film constituting the first retardation region is preferably 20 μm or more and 200 μm or less from the viewpoint of corner unevenness suppression and manufacturing suitability.

2. Second retardation region The second retardation region disposed between the front polarizer and the liquid crystal cell has an optical characteristic that improves contrast in an oblique direction and reduces color shift during black display. It is preferably adjusted so that it can contribute. An example of a preferable second retardation region is 30 nm ≦ Re (590) ≦ 90 nm and 170 nm ≦ Rth (590) ≦ 300 nm.
Is a phase difference region satisfying the above. Within this range, light leakage in an oblique direction during black display of a general VA liquid crystal cell (Δnd (590) is about 180 to 350 nm) can be reduced.
Furthermore, as described above, the retardation of the second retardation region, particularly the preferable range of Rth, varies according to the value of Δnd (λ) of the liquid crystal layer. Here, when Rth of the first retardation region at wavelength λ is Rth ₁ (λ) and Rth of the second retardation region is Rth ₂ (λ), Δnd (λ) of the liquid crystal layer and the first position An example of a more preferable second phase difference region with respect to Rth (λ) of the phase difference region is
Δnd (590) −70 ≦ Rth ₁ (590) + Rth ₂ (590) ≦ Δnd (590) −10
A phase difference region satisfying
Δnd (590) −60 ≦ Rth ₁ (590) + Rth ₂ (590) ≦ Δnd (590) −20
Is a phase difference region satisfying the above. Within this range, light leakage in an oblique direction during black display of the VA liquid crystal cell can be further reduced.
Further, as described above, in order to increase the transmittance during white display (= increase the front CR), it is preferable that Δnd (590) of the liquid crystal layer is 280 nm or more and 340 nm or less. In this case, the second phase difference region disposed on the front side is
220 nm ≦ Rth (590) ≦ 280 nm
It is preferable that
230 nm ≦ Rth (590) ≦ 280 nm
It is more preferable that
On the other hand, when manufacturing aptitude is considered, a configuration using a retardation film of Rth (590) ≦ 230 nm may be preferable as the second retardation region. In general, in order to obtain a retardation film having a high retardation, it is necessary to perform a stretching treatment with a high stretching ratio or increase the amount of an additive that contributes to the expression of the retardation. This is because when the magnification is high, the film is likely to be cut, and when the amount of the additive is increased, the additive may ooze out from the film.
In order to use a retardation film of Rth (590) ≦ 230 nm, Δnd (590) of the liquid crystal cell is preferably Δnd (590) ≦ 290 nm, and more preferably Δnd (590) ≦ 280 nm. .

The second retardation region may be a single retardation film or a laminate of two or more films. Moreover, there is no restriction | limiting in particular about the material, as long as the said characteristic is satisfied. Various polymer films such as cellulose acylate, polycarbonate polymer, polyester polymer such as polyethylene terephthalate and polyethylene naphthalate, acrylic polymer such as polymethyl methacrylate, polystyrene, acrylonitrile / styrene copolymer (AS resin), etc. Styrene polymers and the like can be used. Polyolefins such as polyethylene and polypropylene, polyolefin polymers such as ethylene / propylene copolymers, vinyl chloride polymers, amide polymers such as nylon and aromatic polyamide, imide polymers, sulfone polymers, polyethersulfone polymers , Polyether ether ketone polymer, polyphenylene sulfide polymer, vinylidene chloride polymer, vinyl alcohol polymer, vinyl butyral polymer, arylate polymer, polyoxymethylene polymer, epoxy polymer, or polymer mixed with the above polymers, etc. One or two or more polymers are selected from the above, and a polymer film is produced using the polymer as a main component, and the phase constituting the second retardation region in a combination satisfying the above characteristics. It can be used in the production of the film.

As the retardation film constituting the second retardation region, it is preferable to use a cellulose acylate film. As a raw material of a cellulose acylate film that can be used as a retardation film constituting the second retardation region, the acyl substitution degree is preferably 2.00 to 3.00. In addition, the film is adjusted to have a desired retardation by stretching, but from the viewpoint of retardation development during stretching, it is preferable that the acyl substitution degree is low. However, the lower the acyl substitution degree, the higher the Rth of the unstretched film. Therefore, the retardation degree of the VA liquid crystal display device preferably has an acyl substitution degree of 2.00 to 2.65. 20 to 2.65 is more preferable, and 2.30 to 2.60 is even more preferable. On the other hand, in order for the retardation film to exhibit reverse wavelength dispersion, it is preferable that the acyl substitution degree is higher, specifically, 2.65 to 3.00 is preferable, and 2.75 to 3.00. More preferably, it is more preferably 2.80 to 3.00.
The cellulose acylate is preferably cellulose acetate, but may be substituted with an acyl group other than the acetyl group instead of the acetyl group or together with the acetyl group. Among these, cellulose acylate having at least one acyl group selected from acetyl, propionyl and butyryl groups is preferable, and cellulose acylate having at least two acyl groups selected from acetyl, propionyl and butyryl groups is more preferable. Further, a cellulose acylate having an acetyl group and a propionyl and / or butyryl group is preferable, the substitution degree of the acetyl group is 1.0 to 2.97, and the substitution degree of the propionyl and / or butyryl group is 0.2 to A cellulose acylate of 2.5 is more preferred.

The cellulose acylate preferably has a mass average degree of polymerization of 200 to 800, more preferably 250 to 550. The cellulose acylate used in the present invention preferably has a number average molecular weight of 70000 to 230,000, more preferably a number average molecular weight of 75000 to 230,000, and more preferably a number average molecular weight of 78000 to 120,000. Further preferred.

It is the same as the raw material of cellulose acylate that can be used as the retardation film constituting the first retardation region, except that the first retardation region such as a compound that reduces optical anisotropy is constituted. It is preferable that the additive used for producing the cellulose acylate film for retardation film is not used for producing the cellulose acylate film for retardation film constituting the second retardation region. On the other hand, for producing a cellulose acylate film for retardation film constituting the second retardation region, it is preferable to use a retardation enhancer as an additive. Examples of the retardation developer that can be used include a rod-like or discotic compound and a positive birefringent compound. As the rod-like or discotic compound, a compound having at least two aromatic rings can be preferably used as a retardation developer. The addition amount of the retardation developer composed of the rod-like compound is preferably 0.1 to 30 parts by mass, and preferably 0.5 to 20 parts by mass with respect to 100 parts by mass of the polymer component containing cellulose acylate. Is more preferable. The discotic retardation enhancer is preferably used in the range of 0.05 to 20 parts by weight, and in the range of 0.1 to 15 parts by weight, with respect to 100 parts by weight of the cellulose acylate resin. It is more preferable to use in the range of 0.1 to 10 parts by mass.
Since the discotic compound is superior to the rod-like compound in Rth retardation expression, it is preferably used when a particularly large Rth retardation is required. Two or more retardation developers may be used in combination.
The retardation developing agent preferably has a maximum absorption in the wavelength region of 250 to 400 nm, and preferably has substantially no absorption in the visible region.

(1) Discotic compound The discotic compound will be described. As the discotic compound, a compound having at least two aromatic rings can be used.
In the present specification, the “aromatic ring” includes an aromatic heterocycle in addition to an aromatic hydrocarbon ring. Examples of the discotic compound that can be used in the present invention include compounds described in JP-A 2008-181105, [0038] to [0046].

Examples of the discotic compound that can be used for producing the retardation film constituting the second retardation region include compounds represented by the following general formula (I).

In the formula, X ¹ is a single bond, —NR ⁴ —, —O— or S—; X ² is a single bond, —NR ⁵ —, —O— or S—; X ³ is a single bond A bond, —NR ⁶ —, —O— or S—. R ¹ , R ² , and R ³ are each independently an alkyl group, an alkenyl group, an aromatic ring group, or a heterocyclic group; R ⁴ , R ^5, and R ⁶ are each independently a hydrogen atom , An alkyl group, an alkenyl group, an aryl group or a heterocyclic group.

Preferred examples (I- (1) to IV- (10)) of the compounds represented by the general formula (I) are shown below, but the present invention is not limited to these specific examples.

(2) Rod-shaped compound In the present invention, a rod-shaped compound having a linear molecular structure can be preferably used in addition to the aforementioned disk-shaped compound. Examples of the rod-like compound that can be used in the present invention include compounds described in [0053] to [0095] of JP-A-2007-268898.

(3) Positive birefringent compound A positive birefringent compound is a compound in which light is incident on a layer formed with a uniaxial orientation of molecules, and the refractive index of light in the orientation direction is the orientation direction. Refers to a polymer that is greater than the refractive index of light in the direction orthogonal to the.
Such a positive birefringent compound is not particularly limited, and examples thereof include polymers having a positive intrinsic birefringence value such as polyamide, polyimide, polyester, polyetherketone, polyamideimide and polyesterimide. Ketones and polyester polymers are preferred, and polyester polymers are more preferred.

The polyester polymer includes a mixture of an aliphatic dicarboxylic acid having 2 to 20 carbon atoms and an aromatic dicarboxylic acid having 8 to 20 carbon atoms, an aliphatic diol having 2 to 12 carbon atoms, and an alkyl ether diol having 4 to 20 carbon atoms. And at least one diol selected from aromatic diols having 6 to 20 carbon atoms, and both ends of the reaction product may remain as the reaction product. Alcohols or phenols may be reacted to perform so-called end sealing. It is effective in terms of storage stability that the end capping is performed in particular so as not to contain free carboxylic acids. The dicarboxylic acid used in the polyester polymer of the present invention is preferably an aliphatic dicarboxylic acid residue having 4 to 20 carbon atoms or an aromatic dicarboxylic acid residue having 8 to 20 carbon atoms.

Examples of the aliphatic dicarboxylic acid having 2 to 20 carbon atoms preferably used include oxalic acid, malonic acid, succinic acid, maleic acid, fumaric acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, and sebacic acid. , Dodecanedicarboxylic acid and 1,4-cyclohexanedicarboxylic acid.
Examples of the aromatic dicarboxylic acid having 8 to 20 carbon atoms include phthalic acid, terephthalic acid, isophthalic acid, 1,5-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 2,8 -Naphthalenedicarboxylic acid and 2,6-naphthalenedicarboxylic acid.

Among these, preferable aliphatic dicarboxylic acids are malonic acid, succinic acid, maleic acid, fumaric acid, glutaric acid, adipic acid, azelaic acid, and 1,4-cyclohexanedicarboxylic acid, and aromatic dicarboxylic acid is phthalic acid. Acid, terephthalic acid, isophthalic acid, 1,5-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid. Particularly preferably, the aliphatic dicarboxylic acid component is succinic acid, glutaric acid, and adipic acid, and the aromatic dicarboxylic acid is phthalic acid, terephthalic acid, and isophthalic acid.

Although at least one of each of the above-mentioned aliphatic dicarboxylic acids and aromatic dicarboxylic acids is used in combination, the combination is not particularly limited, and there is no problem even if several types of each component are combined.

Examples of the diol or aromatic ring-containing diol used in the positive birefringent compound include an aliphatic diol having 2 to 20 carbon atoms, an alkyl ether diol having 4 to 20 carbon atoms, and an aromatic having 6 to 20 carbon atoms. It is selected from ring-containing diols.

Examples of the aliphatic diol having 2 to 20 carbon atoms include alkyl diols and alicyclic diols such as ethane diol, 1,2-propane diol, 1,3-propane diol, 1,2-butane. Diol, 1,3-butanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl-1,3-propanediol (neopentyl glycol) ), 2,2-diethyl-1,3-propanediol (3,3-dimethylolpentane), 2-n-butyl-2-ethyl-1,3-propanediol (3,3-dimethylolheptane), 3 -Methyl-1,5-pentanediol, 1,6-hexanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl 1,3-hexanediol, 2-methyl-1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-octadecanediol, and the like. Or it is used as a mixture of two or more.

Preferred aliphatic diols include ethanediol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 2-methyl-1,3-propanediol, 1 , 4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, particularly preferred Is ethanediol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6- Hexanediol, 1,4-cyclohexanediol, and 1,4-cyclohexanedimethanol.

Examples of the alkyl ether diol having 4 to 20 carbon atoms preferably include polytetramethylene ether glycol, polyethylene ether glycol, polypropylene ether glycol, and combinations thereof. The average degree of polymerization is not particularly limited, but is preferably 2 to 20, more preferably 2 to 10, further 2 to 5, and particularly preferably 2 to 4. Examples of these typically commercially available polyether glycols include Carbowax resin, Pluronics® resin and Niax resin.

Examples of the aromatic diol having 6 to 20 carbon atoms include, but are not limited to, bisphenol A, 1,2-hydroxybenzene, 1,3-hydroxybenzene, 1,4-hydroxybenzene, and 1,4-benzenedimethanol. Of these, bisphenol A, 1,4-hydroxybenzene, and 1,4-benzenedimethanol are preferred.

The positive birefringent compound is preferably a compound whose end is sealed with an alkyl group or an aromatic group. This is because the terminal is protected with a hydrophobic functional group, which is effective against deterioration with time at high temperature and high humidity, and is due to the role of delaying hydrolysis of the ester group.
It is preferable to protect with a monoalcohol residue or a monocarboxylic acid residue so that both ends of the positive birefringent compound do not become carboxylic acid or OH group.
In this case, the monoalcohol is preferably a substituted or unsubstituted monoalcohol having 1 to 30 carbon atoms, such as methanol, ethanol, propanol, isopropanol, butanol, isobutanol, pentanol, isopentanol, hexanol, isohexanol, cyclohexyl alcohol. , Octanol, isooctanol, 2-ethylhexyl alcohol, nonyl alcohol, isononyl alcohol, tert-nonyl alcohol, decanol, dodecanol, dodecahexanol, aliphatic alcohols such as dodecaoctanol, allyl alcohol, oleyl alcohol, benzyl alcohol, 3-phenyl Examples include substituted alcohols such as propanol.

End-capping alcohols that can be preferably used are methanol, ethanol, propanol, isopropanol, butanol, isobutanol, isopentanol, hexanol, isohexanol, cyclohexyl alcohol, isooctanol, 2-ethylhexyl alcohol, isononyl alcohol, oleyl alcohol Benzyl alcohol, in particular methanol, ethanol, propanol, isobutanol, cyclohexyl alcohol, 2-ethylhexyl alcohol, isononyl alcohol, benzyl alcohol.

In the case of sealing with a monocarboxylic acid residue, the monocarboxylic acid used as the monocarboxylic acid residue is preferably a substituted or unsubstituted monocarboxylic acid having 1 to 30 carbon atoms. These may be aliphatic monocarboxylic acids or aromatic ring-containing carboxylic acids. Preferred aliphatic monocarboxylic acids are described, for example, acetic acid, propionic acid, butanoic acid, caprylic acid, caproic acid, decanoic acid, dodecanoic acid, stearic acid, oleic acid, and examples of the aromatic ring-containing monocarboxylic acid include Benzoic acid, p-tert-butylbenzoic acid, p-tert-amylbenzoic acid, orthotoluic acid, metatoluic acid, p-toluic acid, dimethylbenzoic acid, ethylbenzoic acid, normal propylbenzoic acid, aminobenzoic acid, acetoxybenzoic acid, etc. Yes, these can be used alone or in combination of two or more.

The positive birefringent compound may be synthesized by a hot melt condensation method using a polyesterification reaction or a transesterification reaction between the dicarboxylic acid and a diol and / or a monocarboxylic acid or monoalcohol for end-capping according to a conventional method, Alternatively, it can be easily synthesized by any of the interfacial condensation methods of acid chlorides of these acids and glycols. These polyester-based additives are described in detail in Koichi Murai, “Additives, Theory and Application” (Kokaibo Co., Ltd., first edition published on March 1, 1973). Also, JP-A Nos. 05-155809, 05-155810, JP-A-5-97073, JP-A-2006-259494, JP-A-07-330670, JP-A-2006-342227, JP-A-2007-003679. The materials described in each publication can also be used.
Specific examples of the positive birefringent compound are described below, but the positive birefringent compound that can be used in the present invention is not limited thereto.

In Tables 1 and 2, PA is phthalic acid, TPA is terephthalic acid, IPA is isophthalic acid, AA is adipic acid, SA is succinic acid, and 2,6-NPA is 2,6-naphthalenedicarboxylic acid. 2,8-NPA is 2,8-naphthalenedicarboxylic acid, 1,5-NPA is 1,5-naphthalenedicarboxylic acid, 1,4-NPA is 1,4-naphthalenedicarboxylic acid, 1,8 -NPA represents 1,8-naphthalenedicarboxylic acid, respectively.

The addition amount of the positive birefringent compound is preferably 1 to 30 parts by mass, more preferably 4 to 25 parts by mass with respect to 100 parts by mass of the cellulose acylate resin. It is particularly preferable that the amount be ˜20 parts by mass.

The cellulose acylate solution used for the production of the cellulose acylate film may have other additives in addition to the retardation developer. Examples of other additives include antioxidants, ultraviolet absorbers, peeling accelerators, plasticizers, and the like, and any known additive can be used.

A plasticizer can be added to the cellulose acylate solution in order to improve the mechanical properties of the resulting film or to improve the drying speed. Examples of the plasticizer that can be used in the present invention include compounds described in JP-A-2008-181105, [0067].

Also, as the retardation film constituting the second retardation region, it is also preferable to use a cyclic olefin polymer film. The raw material of the cyclic olefin polymer film, the production method thereof, and the production method of the film using the raw material are described in detail in [0098] to [0193] of JP-A-2006-293342. Can be referred to. Examples of the cyclic olefin-based polymer film that can be used as the retardation film constituting the second retardation region include a norbornene-based polymer film, and commercially available polymers include Arton (manufactured by JSR) and Zeonore (manufactured by Nippon Zeon). ) Etc. can be used.

The various polymer films used as the retardation film constituting the second retardation region can be produced by various methods. Examples thereof include a solution casting method (solution casting method), a melt extrusion method, a calendar method, and a compression molding method. Of these film forming methods, the solution casting method (solution casting method) and the melt extrusion method are particularly preferable. In addition, the various polymer films used as the retardation film constituting the second retardation region may be films that are formed and then subjected to a stretching treatment. The film may be stretched uniaxially or biaxially. It is preferable to perform biaxial stretching treatment simultaneously or sequentially. In order to achieve a large optical anisotropy, it is necessary to stretch the film at a high stretch ratio. For example, the film is preferably stretched in the width direction of the film and in the longitudinal direction (flow direction) of the film. The draw ratio is preferably about 3 to 100%. The stretching process can be performed using a tenter. Further, longitudinal stretching may be performed between the rolls.

Further, the retardation film constituting the second retardation region may be a layer formed by fixing the alignment state after the liquid crystal composition is in a desired alignment state, or together with the layer. A laminate having a polymer film that supports the layer may be used. In the latter embodiment, the polymer film can be used as a protective film for a polarizer. Examples of the liquid crystal that can be used for the production of the retardation film constituting the second retardation region include various liquid crystals such as a rod-like liquid crystal, a disk-like liquid crystal, and a cholesteric liquid crystal.

In order to obtain a higher front CR, the haze of the retardation film constituting the second retardation region disposed on the front side is preferably 0.5 or less, more preferably 0.3 or less, and 0.2 The following is more preferable.

In order to suppress corner unevenness, it is necessary to reduce the deformation of the retardation film due to the stress applied to the retardation film. The thickness of the retardation film constituting the second retardation region arranged on the front side is preferably 20 μm or more and 200 μm or less from the viewpoint of suppressing corner unevenness and manufacturing suitability.

3. Polarizer There is no particular limitation on the polarizer disposed on the front side and the rear side. A commonly used linearly polarizing film can be used. The linear polarizing film is manufactured by Optiva Inc. And a polarizing film comprising a binder and iodine or a dichroic dye is preferable. The iodine and the dichroic dye in the linearly polarizing film exhibit polarizing performance by being oriented in the binder. It is preferable that the iodine and the dichroic dye are aligned along the binder molecule, or the dichroic dye is aligned in one direction by self-assembly such as liquid crystal. Currently, commercially available polarizers are made by immersing a stretched polymer in a solution of iodine or dichroic dye in a bath and allowing iodine or dichroic dye to penetrate into the binder. Is common.

4). Protective film It is preferable that the protective film is bonded to both surfaces of the front-side polarizer and the rear-side polarizer. However, as shown in FIG. 1, the protective film on the surface of the polarizer on the liquid crystal cell side is omitted in an embodiment in which the first and second retardation regions are made of a single film and the film also functions as a protective film. be able to. In the aspect in which the protective film and the one or more retardation films are disposed between the rear-side polarizer and the liquid crystal cell, the protective film and the one or more retardation films are the first as the entire laminate. Satisfies the optical characteristics required for the phase difference region. About the preferable material of the said protective film, it is the same as that of the preferable material of the phase film which comprises a 1st phase difference area | region.

In the aspect in which the protective film and the one or more retardation films are disposed between the front polarizer and the liquid crystal cell, the protective film and the one or more retardation films are the second layer as a whole. It is preferable to satisfy the optical characteristics required for the phase difference region. The protective film, together with one or more retardation films, has an effect of improving contrast in an oblique direction and reducing color shift during black display, that is, a retardation film exhibiting a certain amount of Re and Rth. May be.

There is no particular limitation on the protective film disposed outside the front side polarizer and the rear side polarizer. Various polymer films can be used. This is the same as the example of the phase film constituting the first retardation region. For example, cellulose acylates (eg, films of cellulose acetate, cellulose propionate, cellulose butyrate, etc.), polyolefins (eg, norbornene polymers, polypropylene), poly (meth) acrylic acid esters (eg, polymethyl methacrylate) Examples thereof include, but are not limited to, films mainly composed of polycarbonate, polyester, or polysulfone. Commercially available polymer films ("TD80UL" (manufactured by Fujifilm) for cellulose acylates), arton (manufactured by JSR), zeonore (manufactured by Nippon Zeon) and the like for norbornene-based polymers can also be used.

The present invention will be described more specifically with reference to the following examples. The materials, reagents, amounts and ratios of substances, operations, and the like shown in the following examples can be appropriately changed without departing from the gist of the present invention. Therefore, the scope of the present invention is not limited to the following specific examples.
1. Production of Films 1 to 6 Cellulose acylates having different types of acyl groups and different degrees of substitution described in the following table were prepared. This was carried out by adding sulfuric acid (7.8 parts by mass with respect to 100 parts by mass of cellulose) as a catalyst, adding carboxylic acid as a raw material for the acyl substituent, and carrying out an acylation reaction at 40 ° C. At this time, the kind and substitution degree of the acyl group were adjusted by adjusting the kind and amount of the carboxylic acid. Moreover, it age | cure | ripened at 40 degreeC after acylation. Further, the low molecular weight component of the cellulose acylate was removed by washing with acetone. In addition, Ac in a table | surface is an acetyl group and CTA means a cellulose triacetate (The cellulose ester derivative which an acyl group consists only of an acetate group).

(Cellulose acylate solution)
The following composition was placed in a mixing tank, stirred to dissolve each component, further heated to 90 ° C. for about 10 minutes, and then filtered through a filter paper having an average pore size of 34 μm and a sintered metal filter having an average pore size of 10 μm.
―――――――――――――――――――――――――――――――――
Cellulose acylate solution ――――――――――――――――――――――――――――――――――
Cellulose acylate 100.0 parts by mass Triphenyl phosphate (TPP) 7.8 parts by mass Biphenyl diphenyl phosphate (BDP) 3.9 parts by mass Methylene chloride 403.0 parts by mass Methanol 60.2 parts by mass ――――――――――――――――――――――――――

(Matting agent dispersion)
Next, the following composition containing the cellulose acylate solution prepared by the above method was charged into a disperser to prepare a matting agent dispersion.
――――――――――――――――――――――――――――――――――
Matting agent dispersion ――――――――――――――――――――――――――――――――――
Silica particles having an average particle diameter of 16 nm (aerosil R972, manufactured by Nippon Aerosil Co., Ltd.) 2.0 parts by mass Methylene chloride 72.4 parts by mass Methanol 10.8 parts by mass Cellulose acylate solution 10.3 parts by mass ――――――――――――――――――――――――――――

(Additive solution)
Next, the following composition containing the cellulose acylate solution prepared by the above method was put into a mixing tank and dissolved by stirring while heating to prepare an additive solution.
―――――――――――――――――――――――――――――――――
Additive solution ―――――――――――――――――――――――――――――――――
Retardation agent (1) 20.0 parts by mass Methylene chloride 58.3 parts by mass Methanol 8.7 parts by mass Cellulose acylate solution 12.8 parts by mass ――――――――――――――― ―――――――――――――――――

100 parts by mass of the cellulose acylate solution, 1.35 parts by mass of the matting agent dispersion, and an additive solution in an amount such that the addition amount of the retardation developer (1) in the cellulose acylate film is 10 parts by mass. Were mixed to prepare a dope for film formation. The addition ratio of the additive is shown in parts by mass when the amount of cellulose acylate is 100 parts by mass.
Cotton and additives were changed as described in the following table to prepare the above solutions and dispersions.
Here, the abbreviations of additives and plasticizers described in the following table are as follows.
CTA: triacetyl cellulose TPP: triphenyl phosphate BDP: biphenyl diphenyl phosphate

The above dope was cast using a band casting machine. The film stripped from the band with the residual solvent amount described in the following table is stretched in the longitudinal direction at the stretch ratio described in the following table in the section from stripping to the tenter, and then stretched in the table below using the tenter The film was stretched in the width direction at a magnification, and immediately after transverse stretching, the film was removed from the tenter after shrinking (relaxing) in the width direction at the magnification described in the following table, and a cellulose acylate film was formed. The residual solvent amount of the film when the tenter was removed was as shown in the following table. Both ends were cut off in front of the winding part to make a width of 2000 mm and wound up as a roll film having a length of 4000 m. The draw ratio is shown in the following table. About the produced cellulose acylate film, Re retardation value and Rth retardation value at a wavelength of 590 nm were measured at 25 ° C. and 60% RH. The results are listed in the table below. Rth (λ) was calculated with an average refractive index of 1.48.

2. Production of Film 7 A retardation film 7 having Re (590) 77 nm and Rth (590) 47 nm was obtained in the same manner as the optical compensation A layer described in Example 2 of JP-A-2003-315556.

3. Production of Film 8 A Z-TAC film (manufactured by Fuji Film, Re (590) = 1 nm, Rth (590) = − 1 nm) was prepared. Separately, Re (590) 1.5 nm, Rth (590) 207 nm retardation film 8a was obtained in the same manner as the optical compensation B layer described in Example 2 of JP-A-2003-315556. This retardation film 8a was bonded to the surface of Z-TAC to produce a laminated film, and used as film 8.

4). Production of Film 9 The following composition was placed in a mixing tank, stirred while heating to dissolve each component, and a cellulose acylate solution C was prepared.
<Cellulose acylate solution C composition>
Cellulose acetate having a substitution degree of 2.86 100 parts by mass Methylene chloride (first solvent) 300 parts by mass Methanol (second solvent) 54 parts by mass 1-butanol 11 parts by mass

The following composition was charged into another mixing tank, stirred while heating to dissolve each component, and an additive solution D was prepared.
<Additive solution D composition>
Methylene chloride 80 parts by mass Methanol 20 parts by mass The following optical anisotropy reducing agent A-7 40 parts by mass

A dope was prepared by adding 40 parts by mass of the additive solution D to 465 parts by mass of the cellulose acylate solution C. The transparency of this dope solution was good at 85% or more.
This dope was cast on a support to produce a cellulose acylate film having a thickness of 80 μm. This was used as film 9.

5. Production of Film 10 A stretched film (protective film A) was produced according to the description in [0223] to [0226] of JP-A No. 2007-127893. An easy-adhesion layer coating composition P-2 is prepared on the surface of the protective film A according to the description in [0232] of the publication, and the composition is stretched according to the method described in [0246] of the publication. An easy-adhesion layer was formed by coating on the surface of the film. This film was used as film 10.

6). Preparation of Film 11 A commercially available triacetyl cellulose film “TF80UL” (manufactured by Fuji Film) was prepared as the film 11.

7). Preparation of films 12 to 16 (preparation of polymer solution)
1) Cellulose acylate From the following cellulose acylates A and B, it was selected and used as described in Table 4 below. Each cellulose acylate was heated to 120 ° C. and dried to adjust the water content to 0.5% by mass or less, and then 20 parts by mass was used.
Cellulose acylate A:
A cellulose acetate powder having a substitution degree of 2.93 was used. Cellulose acylate A had a viscosity average degree of polymerization of 300 and a 6-position acetyl group substitution degree of 0.94.
Cellulose acylate B:
A cellulose acetate powder having a substitution degree of 2.86 was used. Cellulose acylate B has a viscosity average degree of polymerization of 300, an acetyl group substitution degree at the 6-position of 0.89, an acetone extract of 7% by mass, a mass average molecular weight / number average molecular weight ratio of 2.3, and a water content of 0.3. Viscosity in 2 mass% and 6 mass% dichloromethane solutions is 305 mPa · s, residual acetic acid content is 0.1 mass% or less, Ca content is 65 ppm, Mg content is 26 ppm, iron content is 0.8 ppm, sulfate ion The content was 18 ppm, the yellow index was 1.9, and the amount of free acetic acid was 47 ppm. The average particle size of the powder was 1.5 mm, and the standard deviation was 0.5 mm.

2) Solvent The following solvent A was used. The water content of each solvent was 0.2% by mass or less.
・ Solvent A
Dichloromethane / methanol = 90/10 parts by mass

3) Additives Among the following Additives A and B, those listed in Table 4 below were selected and used.
・ Additive A
Silicon dioxide fine particles (particle size 20 nm, Mohs hardness about 7) (0.08 parts by mass)
・ Additive B
Triphenyl phosphate (1.6 parts by mass)
Biphenyl diphenyl phosphate (0.8 parts by mass)
Silicon dioxide fine particles (particle size 20 nm, Mohs hardness about 7) (0.08 parts by mass)

4) Dissolution Swelling and dissolution were performed using the following dissolution step A.
・ Dissolution process A
The cellulose acylate was gradually added to the 400 liter stainless steel dissolution tank having a stirring blade and circulating cooling water around the outer periphery, while stirring and dispersing the solvent and additive. After completion of the addition, the mixture was stirred at room temperature for 2 hours, swollen for 3 hours and then stirred again to obtain a cellulose acylate swelling solution.
For the stirring, a dissolver type eccentric stirring shaft that stirs at a peripheral speed of 15 m / sec (shear stress 5 × 10 ⁴ kgf / m / sec ² [4.9 × 10 ⁵ N / m / sec ² ]). And an agitating shaft having an anchor blade on the central axis and stirring at a peripheral speed of 1 m / sec (shear stress 1 × 10 ⁴ kgf / m / sec ² [9.8 × 10 ⁴ N / m / sec ² ]) It was. Swelling was carried out with the high speed stirring shaft stopped and the peripheral speed of the stirring shaft having anchor blades set at 0.5 m / sec.
The swollen solution was heated from a tank to 50 ° C. with a jacketed pipe, and further heated to 90 ° C. under a pressure of 2 MPa to completely dissolve. The heating time was 15 minutes. At this time, filters, housings, and pipes that were exposed to high temperature were made of Hastelloy alloy and had excellent corrosion resistance, and those having a jacket for circulating a heat medium for heat retention and heating were used.
Next, the temperature was lowered to 36 ° C. to obtain a cellulose acylate solution.

5) Filtration The obtained cellulose acylate solution was filtered with a filter paper (# 63, manufactured by Toyo Roshi Kaisha, Ltd.) having an absolute filtration accuracy of 10 μm, and further a sintered metal filter (FH025, Pole Corporation) having an absolute filtration accuracy of 2.5 μm. To obtain a polymer solution.

(Production of film)
The film was formed by the following film forming step A.
・ Film formation process A
The cellulose acylate solution was heated to 30 ° C., and cast on a mirror surface stainless steel support having a band length of 60 m set at 15 ° C. through a casting Giesa (described in JP-A-11-314233). The casting speed was 50 m / min and the coating width was 200 cm. The space temperature of the entire casting part was set to 15 ° C. Then, the cellulose acylate film that had been cast and rotated 50 cm before the end point of the casting part was peeled off from the band, and 45 ° C. dry air was blown. Next, it was dried at 110 ° C. for 5 minutes and further at 140 ° C. for 10 minutes to obtain a transparent film of cellulose acylate.

(Stretching)
As shown in Table 4 below, the stretching step was performed by either of the following stretching steps A or B.
・ Extension process A
The resulting film was stretched using an apparatus having a heating zone between two nip rolls. The distance between the nip rolls was adjusted so that the aspect ratio (distance between nip rolls / base inlet width) was 0.1, the base temperature before entering the heating zone was 25 ° C., and the heating zone was listed in Table 4 below. It was temperature. Further, by adjusting the speed ratio between the speed of the feeding nip roll and the speed of the take-up nip roll, it was adjusted so that the draw ratios shown in Table 4 below were obtained.

・ Extension process B
After gripping both ends of the obtained film with a tenter clip, the film was stretched in a direction perpendicular to the transport direction in the heating zone. The heating zone was set to the temperature described in Table 4 below, and the draw ratio calculated from the expansion / contraction rate of the tenter was set to the ratio described in Table 4 below.
As described above, films 12 to 16 were produced. The production conditions are summarized in Table 4 below.

8). Preparation of film 17 In preparation of film 4, the same applies except that the addition amount of the retardation enhancer (1) is changed to 12 parts by mass, the longitudinal stretch ratio is changed to 20%, and the lateral stretch ratio is changed to 35%. It was made as follows.

9. Preparation of film 18 In the production of film 5, the addition amount of the retardation enhancer (1) was changed to 7.2 parts by mass, the longitudinal draw ratio was changed to 35%, and the transverse draw ratio was changed to 75%. This was produced in the same manner.

10. Production of Film 19 The surface of a commercially available norbornene polymer film “ZEONOR ZF14-060” (manufactured by Optes Co., Ltd.) was subjected to corona discharge treatment using a solid state corona treatment machine 6KVA (manufactured by Pillar Co., Ltd.). This film was used as film 19. The thickness of this film was 60 μm.

11. Production of Film 20 The surface of a commercially available cycloolefin polymer film “ARTON FLZR50” (manufactured by JSR Corporation) was subjected to corona discharge treatment in the same manner as film 18. This film was used as film 20. The thickness of this film was 50 μm.

12 Production of film 21 A commercially available norbornene polymer film “ZEONOR ZF14-100” (manufactured by Optes Co., Ltd.) is fixed at a fixed end biaxially at 1.55 times in the MD direction and 1.8 times in the TD direction at a temperature of 142 ° C. After stretching, the surface was subjected to corona discharge treatment using a solid state corona treatment machine 6KVA (manufactured by Pillar Co., Ltd.). This film was used as film 21. The thickness of this film was 38 μm.

13. Preparation of Film 22 Cellulose acylate propionate (“CAP482-20” (manufactured by Eastman Chemical Co.); acetyl substitution degree 0.2, propionyl group substitution degree 2.4) was prepared. To this, 8% by mass of 1,4-phenylene-tetraphenyl phosphate as a plasticizer and 0.5% by mass of IRGANOX-1010 (manufactured by Ciba Specialty Chemicals) as a deterioration inhibitor (antioxidant) are added. For 30 minutes in a tumbler mixer. The obtained mixture was dried with a dehumidifying hot air dryer (Matsui Seisakusho DMZ2) at a hot air temperature of 150 ° C. and a dew point of −36 ° C. Subsequently, this mixture was supplied to a twin screw extruder manufactured by Technobel Co., Ltd., and from the opening of an additive hopper provided in the middle part of the extruder, as a matting agent, AEROSIL 200V (0.016 μm silica fine particles). (Manufactured by Nippon Aerosil Co., Ltd.) with a continuous feeder so as to be 0.05% of the extrusion amount, and TINUVIN 360 (manufactured by Ciba Specialty Chemicals) as an ultraviolet absorber It added so that it might become 0.5%, and melt-extruded. The film thickness of the melt-extruded film was 220 μm.
Further, this film was stretched at a temperature of 142 ° C. in the MD direction by 1.3 times and in the TD direction by 2.4 times to produce a fixed end biaxial stretch. This film was used as film 22. The film thickness of this film was 70 μm.

14 Production of film 23 Production of film 1 was carried out in the same manner as production of film 1 except that cellulose acylate shown in the following table was used as a raw material and production conditions were changed as shown in the following table. And used as film 23. In addition, the abbreviations of the following additives and plasticizers are as defined above.

15. Production of film 24 (preparation of polymer solution)
1) Polymer A polycarbonate copolymer containing bisphenol A and 9,9-bis (4-hydroxy-3-methylphenyl) fluorene as a bisphenol component was used. The polymer was heated to 120 ° C. and dried to adjust the water content to 0.5% by mass or less, and then 20 parts by mass was used.

2) Solvent The following solvent A was used. The water content of each solvent was 0.2% by mass or less.
・ Solvent A
Dichloromethane = 100 parts by mass

3) Additive The following additive A was used.
・ Additive A
Silicon dioxide fine particles (particle size 20 nm, Mohs hardness about 7) (0.08 parts by mass)

4) Dissolution Swelling and dissolution were performed by the following dissolution step A.
・ Dissolution process A
The polymer was gradually added to the 400 liter stainless steel dissolution tank having stirring blades and circulating cooling water around the outer periphery, while stirring and dispersing the solvent and additive. After completion of the addition, the mixture was stirred at room temperature for 2 hours to obtain a polymer solution.

5) Filtration The obtained polymer solution was filtered with a filter paper (# 63, manufactured by Toyo Roshi Kaisha, Ltd.) with an absolute filtration accuracy of 10 μm, and further a sintered metal filter (FH025, manufactured by Pall) with an absolute filtration accuracy of 2.5 μm. To obtain a polymer solution.

(Production of film)
Film formation was performed by the following film formation process A.
・ Film formation process A
The polymer solution was heated to 30 ° C. and cast on a mirror surface stainless steel support having a band length of 60 m set at 15 ° C. through a casting Giesa (described in JP-A-11-314233). The casting speed was 10 m / min and the coating width was 150 cm. The space temperature of the entire casting part was set to 15 ° C. And the polymer film which was cast and rotated 50 cm before the end point of the casting part was peeled off from the band, and 45 ° C. drying air was blown. Next, it was dried at 110 ° C. for 5 minutes and further at 140 ° C. for 10 minutes to obtain a transparent polymer film.

(Stretching)
The following stretching process A was performed.
・ Extension process A
The resulting film was stretched using an apparatus having a heating zone between two nip rolls. The distance between nip rolls was adjusted so that the aspect ratio (distance between nip rolls / base inlet width) was 8, the base temperature before entering the heating zone was 25 ° C., and the heating zone was 210 ° C. The film was stretched by giving a speed ratio between the speed of the feeding nip roll and the speed of the take-off nip roll to obtain a transparent polymer film having Re / Rth = 140/72 nm.

16. Fabrication of Film 25 Polyimide synthesized from 2,2′-bis (3,4-dicarboxyphenyl) hexafluoropropane and 2,2′-bis (trifluoromethyl) -4,4′-diaminobiphenyl was used as cyclohexanone. Dissolved in a 15% by weight solution. This polyimide solution is applied on a biaxially stretched polyester film (base material) and dried at 120 ° C. for 10 minutes to form a non-liquid crystalline polymer layer (optical compensation B layer) having a thickness of 5 μm. Obtained.
This laminate was bonded to the film 9 produced above using an adhesive. The surface of the optical compensation B layer was brought into contact with the surface of the film 9 and bonded. Then, the base material was removed and the film 25 was produced.

17. Preparation of film 26 The following composition was put into a mixing tank, stirred while being heated to dissolve each component, and then filtered through a filter paper having an average pore size of 34 μm and a sintered metal filter having an average pore size of 10 μm to obtain a cellulose acylate solution. Was prepared.
(Cellulose acylate solution)
Cellulose acetate having a substitution degree of 2.81 100 parts by mass Retardation developer (1) 8.5 parts by mass Retardation developer (3) 7.0 parts by mass Methylene chloride 428.4 parts by mass Methanol 64.0 parts by mass

The composition of the retardation developer (3) is shown in Table 6 below. In Table 6 below, EG represents ethylene glycol, TPA represents terephthalic acid, PA represents phthalic acid, AA represents adipic acid, and SA represents succinic acid. The retardation developer (3) is a non-phosphate ester compound and a compound that functions as a retardation developer. The end of the retardation developer (3) is sealed with an acetyl group.

The above prepared cellulose acylate solution was quickly cast with a band casting machine. The film peeled off from the band with a residual solvent amount of about 30% by mass was stretched in the width direction by a tenter at a stretch ratio of 16% at 140 ° C. Thereafter, the film was transferred from the tenter conveyance to the roll conveyance, and further dried and wound at 110 ° C. to 150 ° C. to produce a film 26. The film thickness of this film was 85 μm.

In the production of the film 26, problems that occur during the production of the film 1 (smoke during high-temperature treatment in the drying process, malfunctions due to adhesion of the production machine such as volatilized oil, and surface failure due to film adhesion) do not occur It was.
This is because the retardation developing agent (3) used as the retardation developing agent functions as a plasticizer in the production of the film 26, so that conventional low molecular plasticizers such as TPP and BDP used in the production of the film 1 are used. This is because they did not.
Thus, since the above-mentioned problem can be solved by using the positive birefringent compound such as the retardation enhancer (3), the positive birefringent compound is used from the viewpoint of film production. Therefore, it can be said that it is a preferable retardation developer.

18. Production of film 27 (cellulose acylate solution for low substitution layer)
The following composition was put into a mixing tank, stirred while being heated to dissolve each component, and a cellulose acylate solution for a low substitution layer was prepared.
Cellulose acetate with a degree of substitution of 2.43 100 parts by weight retardation developer (1) 4.0 parts by weight retardation developer (4) 10.0 parts by weight methylene chloride 351.5 parts by weight Methanol 52.5 parts by weight

The composition of the retardation developer (4) is shown in Table 7 below. In Table 7, EG represents ethylene glycol, PG represents propylene glycol, BG represents butylene glycol, TPA represents terephthalic acid, PA represents phthalic acid, AA represents adipic acid, and SA represents succinic acid. ing. The retardation developer (4) is a non-phosphate ester compound and a compound that functions as a retardation developer. The terminal of the retardation developer (4) is sealed with an acetyl group.

(Cellulose acylate solution for high substitution layer)
The following composition was put into a mixing tank and stirred to dissolve each component to prepare a cellulose acylate solution for a high substitution degree layer.
Cellulose acetate with a substitution degree of 2.79 100.0 parts by mass Retardation developer (4) 11.0 parts by mass Silica particles with an average particle size of 16 nm (Aerosil R972, manufactured by Nippon Aerosil Co., Ltd.) 0.15 parts by mass methylene chloride 395 0.0 part by mass methanol 9.0 parts by mass

(Production of cellulose acylate sample)
In order to form a core layer having a film thickness of 82 μm from the cellulose acylate solution for the low substitution degree layer and a skin A layer and a skin B layer having a film thickness of 2 μm from the cellulose acylate solution for the high substitution degree layer, respectively. Extended. The obtained film was peeled from the band, and was sandwiched between clips. When the amount of residual solvent relative to the total mass of the film was 20%, the film was stretched horizontally using a tenter at a stretching temperature of 180 ° C. and 18% in the width direction. Thereafter, the clip was removed from the film and dried at 130 ° C. for 20 minutes to produce a film 27.

19. Production of Film 28 Production of film 27 was carried out in the same manner except that the film thickness of the core layer was changed to 75 μm and the draw ratio was changed to 20%.

20. Production of film 29 (cellulose acylate solution for low substitution layer)
The following composition was put into a mixing tank, stirred while being heated to dissolve each component, and a cellulose acylate solution for a low substitution layer was prepared.
Cellulose acetate having a degree of substitution of 2.43 100 parts by mass Retardation developer (4) 18.5 parts by mass Methylene chloride 365.5 parts by mass Methanol 54.6 parts by mass

(Cellulose acylate solution for high substitution layer)
The following composition was put into a mixing tank and stirred to dissolve each component to prepare a cellulose acylate solution for a high substitution degree layer.
Cellulose acetate with a substitution degree of 2.79 100.0 parts by mass Retardation developer (4) 11.0 parts by mass Silica particles with an average particle size of 16 nm (Aerosil R972, manufactured by Nippon Aerosil Co., Ltd.) 0.15 parts by mass methylene chloride 395 .0 parts by mass Methanol 59.0 parts by mass

(Production of cellulose acylate sample)
In order to form a core layer having a film thickness of 37 μm from the cellulose acylate solution for the low substitution degree layer and a skin A layer and a skin B layer having a film thickness of 2 μm from the cellulose acylate solution for the high substitution degree layer, respectively. Extended. The obtained film was peeled from the band, and when the amount of residual solvent with respect to the total mass of the film was 20%, the film was dried at a temperature of 200 ° C. for 30 minutes and then dried at 130 ° C. for 20 minutes to produce a film 29. .

21. Properties of Films 1 to 29 The properties of Films 1 to 29 are summarized in the following table. In addition, Re (590) and Rth (590) of each film were measured at a wavelength of 590 nm using KOBRA21ADH (manufactured by Oji Scientific Instruments Co., Ltd.) after conditioning the sample 30 mm × 40 mm for 2 hours at 25 ° C. and 60% RH. For films 1 to 6, 9, 11 to 18, 22, 23, and 26 to 29, the assumed average refractive index of 1.48 and the film thickness were input and calculated. For the other films, the assumed average refractive index is 1.52 for films 7 and 20, 1.60 for film 8, 1.50 for film 10, and films 19 and 21. 1.53 for film 24, 1.59 for film 24 and 1.58 for film 25.

22. Preparation of Polarizing Plate A polyvinyl alcohol (PVA) film having a thickness of 80 μm is dyed by dipping in an aqueous iodine solution having an iodine concentration of 0.05% by mass at 30 ° C. for 60 seconds, and then boric acid having a boric acid concentration of 4% by mass. While being immersed in an aqueous solution for 60 seconds, the film was longitudinally stretched 5 times the original length and then dried at 50 ° C. for 4 minutes to obtain a polarizing film having a thickness of 20 μm.
Among the films 1 to 29 shown in the above table, cellulose acylate films were saponified as follows. Each film was immersed in an aqueous sodium hydroxide solution at 55 mol C at 1.5 mol / liter, and then the sodium hydroxide was thoroughly washed away with water. Then, after being immersed in a diluted sulfuric acid aqueous solution at 0.005 mol / liter at 35 ° C. for 1 minute, it was immersed in water to sufficiently wash away the diluted sulfuric acid aqueous solution. Finally, the sample was thoroughly dried at 120 ° C.
A laminated polarizing plate was prepared by sandwiching a polarizing film with any two of films 1 to 29. The combinations are shown in the table below.
For the films 1 to 9, 11 to 18, and 22 to 29, which are cellulose acylate films, they are bonded using a polyvinyl alcohol adhesive; The films 19 to 21 were bonded using an acrylic pressure-sensitive adhesive.
For films 1 to 24 and 26 to 28, the in-plane slow axis is bonded in parallel with the transmission axis of the polarizer; and for films 25 and 29, the in-plane slow axis is The films were bonded so as to be orthogonal to the transmission axis of the polarizer.

23. Preparation of VA liquid crystal display device (1) Preparation of liquid crystal cell 1 LC-42RX1W (manufactured by Sharp Corporation) was prepared as a VA liquid crystal display cell. This was used as the liquid crystal cell 1. When Δnd (590) of the liquid crystal cell 1 was measured using AXOSCAN manufactured by AXOMETRICS and the attached software, Δnd (590) was 300 nm.

(2) Preparation of liquid crystal cell 2 (2) -1 Formation of red pixel portion <Formation of curable composition layer (coating film)>
The colored photosensitive composition of Example 17 of JP-A-2009-144126 is further added to the glass substrate (550 mm × 650 mm) on which the black matrix (BM) is formed on one side, and 0.05 mmφ zirconia. Using a bead disperser Ultra Apex Mill (manufactured by Kotobuki Kogyo Co., Ltd.) with beads for 30 minutes, slit coating is performed using a slit coating apparatus equipped with a slit head having a slit interval of 100 μm and an effective coating width of 500 mm. By doing so, a curable composition layer (coating film) was formed.
The slit coating was performed at a coating speed of 100 mm / second by adjusting the distance between the slit and the glass substrate and the discharge amount of the coating liquid so that the film thickness after post-baking was 2.0 μm.

<Exposure, development, cleaning (rinse)>
Next, the obtained curable composition layer was dried (prebaked) at 80 ° C. for 120 seconds using a hot plate, and then the proximity gap was set to 180 μm and 90 mJ using a HITACHI exposure machine LE5565. / Cm ² (illuminance: 20 mW / cm ² ).
The exposed substrate was shower-developed with a 1.0% developer (25 ° C.) of potassium hydroxide developer CDK-1 (manufactured by FUJIFILM Electronics Materials) for 60 seconds and washed with pure water.
Thus, a red pixel portion was formed on the glass substrate. This substrate was post-baked at 220 ° C. for 30 minutes in an oven to obtain a glass substrate on which a red pixel portion was formed.

(2) -2 Formation of green pixel portion Bead dispersion using 0.05 mmφ zirconia beads and the colored photosensitive composition of Example 18 of JP-A-2009-144126 on a glass substrate on which a red pixel portion is formed A green pixel part was formed in the same manner as the red pixel part except that a machine subjected to a dispersion treatment for 30 minutes with a machine ultra apex mill (manufactured by Kotobuki Industries Co., Ltd.) was used. This substrate was post-baked in an oven at 220 ° C. for 30 minutes to obtain a glass substrate on which a red pixel portion and a green pixel portion were formed.

(2) -3 Formation of Blue Pixel Portion The colored photosensitive composition of Example 19 of JP2009-144126A is further added with 0.05 mmφ zirconia beads to the glass substrate on which the red pixel portion and the green pixel portion are formed. A blue pixel portion was formed in the same manner as the red pixel portion except that a dispersion process was performed for 30 minutes with the used bead disperser Ultra Apex Mill (manufactured by Kotobuki Industries Co., Ltd.). This substrate was post-baked in an oven at 230 ° C. for 30 minutes to obtain a color filter substrate.
A transparent electrode of ITO (Indium Tin Oxide) was formed on the produced color filter substrate by sputtering. Next, according to Example 1 of Japanese Patent Application Laid-Open No. 2006-64921, a spacer was formed in a portion corresponding to the upper part of the partition wall (black matrix) on the ITO film. This was used as the front substrate.
Separately, a glass substrate on which an ITO transparent electrode was formed as a counter substrate was prepared, and the color filter substrate and the transparent electrode of the counter substrate were each patterned for the PVA mode, and an alignment film made of vertical polyimide was further provided thereon. .
The liquid crystal cell taken out from the SHARP liquid crystal panel “LC-37GX1W” was disassembled, the array substrate arranged on the light source side was taken out, the surface was washed with ethanol, and then the glass was used on the glass side of the counter substrate. The product array substrate was attached using matching oil. This was used as the rear substrate.
After that, a UV curable resin sealant is applied by a dispenser method at a position corresponding to the outer periphery of the black matrix provided around the RGB pixel group of the color filter on the front substrate, and VA mode liquid crystal is dropped. After bonding to the rear substrate, the bonded substrate was irradiated with UV, and then heat treated to cure the sealant. Thus, the liquid crystal cell 2 was produced.
Subsequently, when ΔND (590) of the produced liquid crystal cell 2 was used with AXOSCAN manufactured by AXOMETRICS and the attached software, Δnd (590) was 300 nm.

(3) Method for Producing Liquid Crystal Cell 3 In the method for producing the color filter substrate, the colored photosensitive composition of Example 17 of JP-A-2009-144126 is used for forming the red pixel portion, and the method for forming the green pixel portion is disclosed. A liquid crystal cell except that the colored photosensitive composition of Example 18 of 2009-144126 was used, and the colored photosensitive composition of Example 19 of JP-A-2009-144126 was used to form a blue pixel portion, respectively. A liquid crystal cell 3 was produced in the same manner as in 2.
Subsequently, when ΔND (590) of the produced liquid crystal cell 3 was used with AXOSCAN manufactured by AXOMETRICS and the attached software, Δnd (590) was 300 nm.

(4) Manufacturing method of the liquid crystal cell 4 Except having used the spacer pattern on a pillar formed in the part corresponding to the partition wall upper part on the ITO film | membrane on a color filter board | substrate with a diameter of 16 micrometers and an average height of 3.0 micrometers, A liquid crystal cell 4 was produced in the same manner as the liquid crystal cell 2.
When Δnd (590) of the produced liquid crystal cell 4 was measured using AXOSCAN manufactured by AXOMETRICS and the attached software, Δnd (590) was 240 nm.

(5) Manufacturing method of liquid crystal cell 5 A glass substrate on which an ITO transparent electrode is formed is prepared, and a transparent columnar spacer pattern having a diameter of 16 μm and an average height of 3.7 μm is formed on the ITO film on the glass substrate. The transparent electrode was patterned for the PVA mode, and an alignment film made of vertical polyimide was further provided thereon to form a front substrate.
A rear substrate was produced in the same manner as in the liquid crystal cell 2.
Thereafter, a UV curable resin sealant was applied onto the pillar spacers of the front substrate by a dispenser method, VA mode liquid crystal was dropped, bonded to the rear substrate, and then the bonded substrate was irradiated with UV. Thereafter, the sealant was cured by heat treatment. Thus, the liquid crystal cell 5 was produced.
Subsequently, Δnd (590) of the produced liquid crystal cell 5 was measured using AXOSCAN manufactured by AXOMETRIC and the attached software, and Δnd (590) was 300 nm.

(6) Manufacturing Method of Liquid Crystal Cell 6 (For Reference Example) In the manufacturing method of the color filter substrate, the colored photosensitive composition of Comparative Example 12 of JP-A-2009-144126 is used for forming the red pixel portion, and the green pixel portion. The colored photosensitive composition of Comparative Example 13 of JP-A-2009-144126 was used for forming, and the colored photosensitive composition of Comparative Example 14 of JP-A-2009-144126 was used for forming the blue pixel portion, respectively. A liquid crystal cell 6 was produced in the same manner as the liquid crystal cell 2 except for the above.

(7) Calculation of the member contrast of the front side substrate and the rear side substrate of the manufactured liquid crystal cell The liquid crystal cell 1 is disassembled, and the substrate arranged on the viewing side is the front side substrate, and the array substrate is arranged on the light source side Was used as the rear side substrate, and after cleaning the surface with ethanol, it was used to calculate the member CR of the front side substrate and the rear side substrate.
A polarizing plate (HLC2-2518, manufactured by Sanlitz) is disposed on the backlight of the liquid crystal panel “LC-32GH5” manufactured by SHARP, and the front side substrate or the rear of the liquid crystal cells 1 to 5 described above is disposed thereon. The side substrate was attached to a rotating stage (SGSP-120YAW, manufactured by Sigma Kogyo Co., Ltd.) and arranged in parallel with the polarizing plate on the light source at 2 mm intervals. At this time, the array wiring on the rear substrate and the black matrix of the front substrate were arranged so as to coincide with the polarization axis of the polarizing plate. Furthermore, a polarizing plate (HLC2-2518, manufactured by Sanlitz) attached to the rotary stage is arranged so that the distance between the polarizing plates is 52 mm, and a measuring instrument (BM5A, manufactured by TOPCON) is used. In a dark room, the luminance values of black display and white display in the normal direction were measured, and front contrast A (white luminance / black luminance) was calculated. Here, when the polarizing plate is rotated, the luminance value when the luminance value is the lowest is set as the luminance value for black display, and the luminance value when the polarizing plate is further rotated by 90 degrees is set as the luminance value for white display.
Next, in the above-described form, the luminance value of black display and white display of only the polarizing plate was measured with the color filter substrate or the array substrate removed, and the front contrast B was calculated.
In order to eliminate the influence of the front contrast B of the polarizing plate on the front contrast A, the member contrast was calculated by the following formula.
Member contrast = 1 / (1 / Front contrast A-1 / Front contrast B)
Based on the calculated member contrast, the member contrast of the front substrate / the member contrast of the rear substrate was calculated and summarized in the table below.

(7) Manufacture of VA type liquid crystal display device A VA type liquid crystal display device was manufactured by laminating polarizing plates on the outer surfaces of both substrates of the liquid crystal cell in the combinations shown in the following table. The polarizing plates were bonded with the absorption axes orthogonal to each other.
As the light source of each liquid crystal display device manufactured, LC-42RX1W (Sharp Co., Ltd.) backlights were used for the liquid crystal cells 1 to 4 and 6, and BGR 3-color LEDs were alternately used at 180 Hz for the liquid crystal cell 5. The following evaluation was performed using the light-emitting element.

24. Evaluation of VA-type liquid crystal display device As the VA-type liquid crystal cell, the liquid crystal cell 1 was used, and each of the liquid crystal display devices of Examples and Comparative Examples was prepared in combination with polarizing plates as shown in the following table.
(1) Measurement of front contrast Using a measuring instrument (BM5A, manufactured by TOPCON), the brightness value of black display and white display in the panel normal direction is measured in a dark room, and the front contrast (white brightness / black brightness) is calculated. Calculated. (2) Measurement of front contrast ratio Using a measuring instrument (BM5A, manufactured by TOPCON), the brightness values of black display and white display in the normal direction of the panel are measured in a dark room, and the front contrast (white brightness / black brightness) is measured. Was calculated. At this time, the distance between the measuring instrument and the panel was set to 700 mm.
Subsequently, the front contrast ratio was calculated by the following formula based on the front contrast ratio in the reference form.
Front contrast ratio = Front contrast in the embodiment / Front contrast in the reference form The reference form is
In the case of the liquid crystal cell 1, the front contrast is 3060 in Comparative Example 10,
Met.

(3) Viewing angle contrast (contrast in diagonal direction)
The light leakage rate during black display in the azimuth direction 45 degrees and polar angle direction 60 degrees from the front of the apparatus was measured. The smaller this value is, the smaller the light leakage in the oblique 45 degree direction, and the better the contrast of the display device, and the viewing angle characteristics of the liquid crystal display device can be evaluated.
“Unacceptable” in the following index means light leakage to the extent that light leakage is recognized even in a bright room.
◎: Light leakage is not recognizable ○: Light leakage is slight △: Light leakage is moderate △ ×: Light leakage is large (unacceptable)
×: There is severe light leakage (unacceptable)

(4) Color shift during black display A change (Δuv) in all azimuth directions at a polar angle of 60 degrees was measured.
“Unacceptable” in the following index means a color change that can be recognized even in a bright room. ◎: Color change is very small ○: Color change is slight Δ: Color change is moderate Δ ×: Color change is not allowed (unacceptable)
×: Severe color change (not acceptable)
(5) Corner irregularity Corner irregularity is caused by the liquid crystal display device being thermo-treated at 50 ° C. and 95% RH for 120 hours, adjusting the humidity to 25 ° C. and 60% RH for 20 hours, turning on the backlight, and leaking light in black display. Was evaluated.
◎: There is no light leakage at the four corners ○: There is a slight light leakage at some of the four corners △: Light leakage at two to three of the four corners (unacceptable)
Δ ×: light leaks at four corners (unacceptable)
×: Clear light leakage at the four corners (unacceptable)

The results are shown in the table below.

* 1 In an Example, the inner side protective film of a rear side polarizing plate corresponds to a 1st phase difference film, and the inner side protective film of a front side polarizing plate corresponds to a 2nd phase difference film.

From the above results, films 9, 10, 13, 15 satisfying | Re (590) | ≦ 10 nm and | Rth (590) | ≦ 25 nm as the inner protective film of the rear polarizing plate, that is, the first retardation film. It can be understood that any of VA type liquid crystal display devices according to the embodiments of the present invention having either. Furthermore, it can be understood that it was favorable from the viewpoints of viewing angle contrast, color shift during black display, and corner unevenness.
On the other hand, in Comparative Example 2 using the film 7 as the inner protective film of the rear-side polarizing plate, the film 7 includes a film that satisfies the characteristics required as the first retardation film. Since there is also a retardation film (retardation film 7a) that does not satisfy the characteristics, it can be understood that the front contrast is lowered.
Comparative Example 1 and Comparative Example 6 have the same configuration except that the rear-side polarizing plate and the front-side polarizing plate of Examples 2 and 5 are replaced, respectively, but between the rear-side polarizer and the liquid crystal cell. It can be understood that the front contrast is lowered because the film 2 does not satisfy the characteristics required for the first retardation film.

In Example 18, the front contrast was high as in Example 1, but the viewing angle contrast was low compared to Example 1. This is because the optical characteristics of the film 28 used as the second retardation film satisfy Δnd (590) −70 nm ≦ Rth ₁ (590) + Rth ₂ (590) ≦ Δnd (590) −10 nm, but almost the lower limit. It is thought that it is a value.

25. Evaluation of VA liquid crystal display device (Characteristics of liquid crystal cell)
Next, in the production of the liquid crystal display device of Example 2, a VA type liquid crystal display device was produced in the same manner as in Example 2 except that the liquid crystal cells 2 to 5 were used instead of the liquid crystal cell 1, and Evaluation was performed in the same manner. The evaluation results are shown in the following table.
However, regarding the front contrast ratio calculated from the following formula, the reference form was as follows.
Front contrast ratio = front contrast in embodiment / front contrast liquid crystal cell 1 in reference form In Comparative Example 10, the front contrast is 3060,
In the case of the liquid crystal cell 2, the front contrast is 3080 in Comparative Example 11.
In the case of the liquid crystal cell 3, the front contrast is 2820 in Comparative Example 12,
In the case of the liquid crystal cell 4, the front contrast is 2480 in the comparative example 13, and in the case of the liquid crystal cell 5, the front contrast is 3950.
Met.

From the results shown in the above table, the front contrast ratio is remarkably improved in any of the liquid crystal cells 1 to 5 in which the member contrast of the front substrate of the liquid crystal cell substrate / the member contrast of the rear substrate is 3.0 or more. I understand that. The liquid crystal cell 5 used in Example 22 is the same as the feed sequential drive liquid crystal cell, that is, from the above results, the effect of the present invention is also remarkable in the feed sequential drive liquid crystal display device. Understandable.
As a reference example, a VA liquid crystal display device manufactured in the same manner as in Example 2 was evaluated in the same manner except that the liquid crystal cell 6 was used instead of the liquid crystal cell 1. In this VA type liquid crystal display device, the effect of improving the front contrast ratio was not obtained so much, and the front contrast ratio was small as compared with Example 2 and Examples 19-22. This is presumably because the liquid crystal cell 6 has a member contrast of the front substrate / member contrast of the rear substrate of 1.7, and thus the effect of the present invention has been reduced.

10

Backlights

14, 14 Polarizer 16 First retardation film (first retardation region)
18 Second retardation film (second retardation region)
20, 22 Outside protective film LC VA liquid crystal cell PL1 Rear side polarizing plate PL2 Front side polarizing plate

Claims

Front-side polarizer, rear-side polarizer, VA liquid crystal cell disposed between the front-side polarizer and rear-side polarizer, and one layer between the rear-side polarizer and the VA-type liquid crystal cell Or it has the 1st phase contrast field which consists of two or more phase contrast layers, and the 1st phase contrast field has the following formula:
0 nm ≦ Re (590) ≦ 10 nm and | Rth (590) | ≦ 25 nm
VA type liquid crystal display device satisfying the following:
However, Re (λ) means in-plane retardation (nm) at the wavelength λnm, and Rth (λ) means retardation in the thickness direction (nm) at the wavelength λnm.
The VA liquid crystal cell has a front side substrate and a rear side substrate, and a ratio (CR f / CR r ) of a member contrast (CR f ) of the front side substrate to a member contrast (CR r ) of the rear side substrate. The VA type liquid crystal display device according to claim 1, wherein the VA type liquid crystal display device is 3 or more.
Between the front side polarizer and the VA type liquid crystal cell, there is a second retardation region composed of one or more retardation layers, and the second retardation region has the following formula:
30 nm ≦ Re (590) ≦ 90 nm and 170 nm ≦ Rth (590) ≦ 300 nm
3. The VA liquid crystal display device according to claim 1, wherein:
The first and second retardation regions have the following formula:
Δnd (590) −70 ≦ Rth 1 (590) + Rth 2 (590) ≦ Δnd (590) −10
The VA liquid crystal display device according to claim 3, wherein:
Where d is the thickness (nm) of the liquid crystal layer of the VA type liquid crystal cell, Δn (λ) is the refractive index anisotropy at the wavelength λ of the liquid crystal layer of the VA type liquid crystal cell, and Δnd (λ) is Δn Rth 1 (λ) is retardation in the thickness direction of the first retardation region at wavelength λ (nm), and Rth 2 (λ) is the second at wavelength λ. Means retardation (nm) in the thickness direction of the retardation region.
The VA liquid crystal display device according to any one of claims 1 to 4, wherein the first retardation region is made of a cellulose acylate film or includes a cellulose acylate film.
Compounds in which the cellulose acylate film decreases the retardation Rth in the thickness direction are represented by the following formulas (I) and (II):
(I) (Rth [A] −Rth [0]) / A ≦ −1.0
(II) 0.01 ≦ A ≦ 30
(Rth [A]: Rth (nm) of a film containing A% of a compound that lowers Rth, Rth [0]: Rth (nm) of a film not containing a compound that reduces Rth, and A: 6. The VA liquid crystal display device according to claim 5, wherein the VA type liquid crystal display device is contained in a range that satisfies a mass (%) of the compound when the mass is 100).
The cellulose acylate-based film comprises a cellulose acylate having an acyl substitution degree of 2.85 to 3.00, at least one compound that reduces in-plane retardation Re and thickness direction retardation Rth, and a cellulose acylate solid content. The VA liquid crystal display device according to claim 5 or 6, wherein the VA type liquid crystal display device is contained in an amount of 0.01 to 30% by mass based on the mass.
The cellulose acylate-based film has at least one compound that reduces | Re (400) -Re (700) | and | Rth (400) -Rth (700) | The VA liquid crystal display device according to any one of claims 5 to 7, wherein the content is 0.01 to 30% by mass.
9. The VA liquid crystal display device according to claim 1, wherein the first retardation region is made of an acrylic polymer film or includes an acrylic polymer film.
The first retardation region is made of an acrylic polymer film containing an acrylic polymer containing at least one unit selected from a lactone ring unit, a maleic anhydride unit, and a glutaric anhydride unit, or the acrylic system The VA liquid crystal display device according to claim 9, which has a polymer film.
The VA liquid crystal display device according to any one of claims 3 to 10, wherein the second retardation region is made of a cellulose acylate film or includes a cellulose acylate film.
The VA liquid crystal display device according to any one of claims 3 to 10, wherein the second retardation region is made of a cyclic olefin polymer film or includes a cyclic olefin polymer film.
The VA liquid crystal display device according to any one of claims 1 to 12, wherein the front contrast is 1500 or more.
The VA liquid crystal display device according to any one of claims 1 to 13, comprising a backlight unit that sequentially emits independent three primary color lights, and is driven by a field sequential driving method.