JP6961710B2 - Liquid crystal display - Google Patents

Description

The present invention relates to a VA (Vertically Aligned) type liquid crystal display device.

In a VA type liquid crystal display device, normally, by arranging retardation films on the front side and the rear side respectively with the liquid crystal cell as the center, the retardation required for optical compensation is shared by each of the two retardation films. Optical compensation has been achieved (see, eg, Patent Documents 1, 5 and 6).

Regarding the liquid crystal cell of the liquid crystal display device, it has been proposed to provide the liquid crystal cell with a color filter-on-array (COA) structure (see, for example, Patent Documents 2, 3 and 4).

Japanese Unexamined Patent Publication No. 2006-184640 Japanese Unexamined Patent Publication No. 2005-99499 Japanese Unexamined Patent Publication No. 2005-258004 Japanese Unexamined Patent Publication No. 2005-3733 Patent No. 5529512 Patent No. 5479179

The VA type liquid crystal display device has an advantage that the contrast in the normal direction (hereinafter referred to as "front CR") is higher than that of the liquid crystal display device of other modes. Further, if the above COA structure is used, the aperture ratio of the pixels can be increased, so that the transmittance at the time of white display can be increased. This is preferable from the viewpoint of environmental protection because it leads to reduction of power consumption. However, since the front CR is determined by the ratio of the two luminance values in white display and black display (luminance value in white display / luminance value in black display), the front CR is further increased in the VA type liquid crystal display device. In order to improve it, it is not enough to increase the brightness at the time of white display.

On the other hand, as for the combination of the retardation films arranged on the front side and the rear side in the VA type liquid crystal display device, the method of arranging the retardation films having the same retardation on the front side and the rear side of the liquid crystal cell is currently the main method. Has been adopted by. In addition, there is a method in which a large retardation is shared by a retardation film arranged on one side of the liquid crystal cell (see, for example, Patent Documents 5 and 6). This method has a cost advantage because a general-purpose retardation film having a low retardation and inexpensive can be used on the other side. Further, as another method, there is also an optical compensation method in which an A plate and a C plate are combined.

By the way, regarding the black display performance of the VA type liquid crystal display device, the present inventors have a viewing angle such as when observing a large panel side by side by a plurality of people or when posting the large panel in a passage so that it can be seen by passersby. Assuming applications that are limited to some extent, we considered responding to the request to prioritize the viewing angle in the horizontal direction rather than the vertical direction. However, as a result of examination, the improvement of the left-right viewing azimuth performance by arranging the same retardation film on the front side and the rear side, which is mainly adopted at present, is when the observation direction is slightly shifted up and down from the left-right direction. The observer noticed the light leakage, and it became clear that there was a limit to the expansion of the viewing angle in the left-right direction.

One aspect of the present invention is an VA type liquid crystal display device including a liquid crystal cell having a COA structure, and an object of the present invention is to provide a VA type liquid crystal display device having improved front CR and black display performance in the left-right direction. do.

One aspect of the present invention is
Includes LCD panel and backlight unit
When the front is the polar angle 0 °, the right direction is the azimuth angle 0 °, the left direction is the azimuth angle 180 °, L (x, y) is the azimuth angle x when black is displayed, and the light leakage amount is the polar angle y. The following formula 1:
L1 (φ, 60) <L (0,60) + L (180,60)
Here, L1 is the amount of light leakage when the azimuth angle is φ and the polar angle is 60 °, and φ is the range of -30 to 30 ° and the range of 150 to 210 °.
The above liquid crystal panel
Front side polarizer,
Rear polarizer,
A VA type liquid crystal cell located between the front-side polarizing element and the rear-side polarizing element,
A front-side retardation layer located between the front-side polarizing element and the VA-type liquid crystal cell, and a rear-side retardation layer located between the rear-side polarizer and the VA-type liquid crystal cell.
Have,
The VA type liquid crystal cell includes a color filter on array substrate on the rear side.
The front side retardation layer includes at least the retardation layer 1.
The in-plane retardation Re (550) measured at a wavelength of 550 nm of the retardation layer 1 is less than 20 nm.
The thickness direction retardation Rth (550) measured at a wavelength of 550 nm of the retardation layer 1 is 200 nm or more and 270 nm or less.
The front side retardation layer or the rear side retardation layer includes at least the retardation layer 2.
The in-plane retardation Re (550) measured at a wavelength of 550 nm of the retardation layer 2 is 130 nm or more and 155 nm or less.
The thickness direction retardation Rth (550) measured at a wavelength of 550 nm of the retardation layer 2 is 55 nm or more and 90 nm or less.
The in-plane retardation Re (450) measured at a wavelength of 450 nm, the in-plane retardation Re (550) measured at a wavelength of 550 nm, and the in-plane retardation Re (650) measured at a wavelength of 650 nm of the retardation layer 2 are
Re (450) ≤ Re (550) ≤ Re (650)
A VA type liquid crystal display device, wherein the retardation layer 1 and the retardation layer 2 include an optically anisotropic layer containing a polymerizable liquid crystal compound.
Regarding.

In one aspect, the in-plane retardation Re (550) of the retardation layer 2 can be 135 nm or more and 150 nm or less, and the thickness direction retardation Rth (550) of the retardation layer 2 is 57 nm or more and 87 nm or less. There can be.

In one aspect, the optically anisotropic layer can be a liquid crystal layer having a thickness of 5.0 μm or less.

In one aspect, the liquid crystal layer can be a cured layer of a polymerizable composition containing a polymerizable liquid crystal compound.

In one aspect, the half width of the emission angle distribution in the vertical direction of the backlight unit can be within 30 °.

In one aspect, the liquid crystal display device can include a diffusion layer on the front surface of the liquid crystal panel.

According to one aspect of the present invention, it is possible to provide a VA type liquid crystal display device provided with a liquid crystal cell having a COA structure, wherein the front CR and the black display performance in the left-right direction are improved. can.

It is sectional drawing which shows an example of the structure of the liquid crystal display device. It is explanatory drawing of the azimuth. It is explanatory drawing of the azimuth. It is explanatory drawing of the azimuth.

Hereinafter, the present invention will be described in detail. The numerical range represented by using "~" in the present specification means a range including the numerical values before and after "~" as the lower limit value and the upper limit value.
First, various terms of the present invention and the present specification will be described.

With respect to retardation, in-plane retardation Re (λ) and Rth (λ) represent in-plane retardation (nm) and thickness direction retardation (nm) at wavelength λ, respectively. Re (λ) is measured by KOBRA 21ADH or WR (manufactured by Oji Measuring Instruments Co., Ltd.) in which light having a wavelength of λ nm is incident on the normal direction of the sample to be measured. When selecting the measurement wavelength λnm, the wavelength selection filter can be replaced manually, or the measured value can be converted by a program or the like for measurement. When the sample to be measured (film, layer, etc.) is represented by a uniaxial or biaxial refractive index ellipsoid, Rth (λ) is calculated by the following method.
Rth (λ) uses the above Re (λ) as the in-plane slow axis (determined by KOBRA 21ADH or WR) as the tilt axis (rotation axis) (in the sample if there is no slow axis). A total of 6 points are measured by injecting light with a wavelength of λ nm from each inclined direction in 10 ° steps from the normal direction to 50 ° on one side with respect to the normal direction of the sample (with an arbitrary direction as the axis of rotation). Then, 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, in the case of a sample having a direction in which the retardation value becomes zero at a certain inclination angle with the slow axis in the plane as the rotation axis from the normal direction, the retardation at an inclination angle larger than the inclination angle. The value is calculated by KOBRA 21ADH or WR after changing its sign to negative.
The retardation value is measured from two arbitrary inclined directions, with the slow axis as the tilt axis (rotation axis) (if there is no slow axis, the rotation axis is any direction in the plane of the sample). , The Rth can be calculated from the following equations (X) and (XI) based on the value, the assumed value of the average refractive index, and the input film thickness value.

The above Re (θ) represents a retardation value in a direction inclined by an angle θ from the normal direction. Further, in the equation, 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 the film thickness.

When the sample to be measured is a sample that cannot be represented by a uniaxial or biaxial refractive index ellipsoid, that is, a sample without a so-called optical axis, Rth (λ) is calculated by the following method.
Rth (λ) is -50 ° to + 50 ° with respect to the normal direction of the sample with the above Re (λ) as the in-plane slow axis (determined by KOBRA 21ADH or WR) as the tilt axis (rotation axis). In 10 ° steps, light with a wavelength of λ nm was incident from the inclined direction and measured at 11 points. Based on the measured retardation value, the assumed value of the average refractive index, and the input film thickness value, KOBRA 21ADH Or WR calculates.
In the above measurement, the value of the polymer handbook (JOHN WILEY & SONS, INC) and the catalog of various optical films can be used as the assumed value of the average refractive index. If the average refractive index value is unknown, it can be measured with an Abbe refractometer. The average refractive index values of the main optical films are illustrated below: cellulose acylate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethylmethacrylate (1.49), It is polystyrene (1.59).
By inputting the assumed value of the average refractive index and the film thickness, KOBRA 21ADH or WR calculates nx, ny, and nz. From this calculated nx, ny, nz, Nz = (nx-nz) / (nx-ny) is further calculated.

Further, the values of Re (λ) and Rth (λ), that is, Re (450), Re (550), Re (650), Rth (550), and Rth (550) differ by 3 or more depending on the measuring device. Re and Rth shall be measured for each wavelength (for example, λ = 479.2, 546.3, 632.8, 745.3 nm) and calculated from those values. Specifically, these measured values are approximated by Cauchy's equation (up to the third term, Re = A + B / λ2 + C / λ4) to obtain the values A, B, and C, respectively. From the above, Re and Rth at wavelength λ can be re-plotted, and Re (λ) and Rth (λ) at each wavelength λ can be obtained from them.
Unless otherwise specified, the measurement wavelength is 550 nm.

For numerical values, numerical ranges, and qualitative expressions (for example, expressions such as "equivalent" and "equal") indicating the optical characteristics of each member such as "phase difference layer" and "liquid crystal layer", the liquid crystal display device and / Or shall be construed to indicate numerical values, numerical ranges and properties that include generally acceptable errors for the members used therein. For example, the angle (for example, an angle such as “90 °”) and its relationship (for example, “orthogonal”, “parallel”, etc.) shall include a range of errors allowed in the technical field to which the present invention belongs. Including the above allowable error range means, for example, that the exact angle is within ± 10 ° or less, and the error from the exact angle is preferably 5 ° or less. More preferably, it is ° or less. For example, in the case of orthogonality, it can be in the range of 90 ° ± 10 ° (80 to 100 °).

The "front side" means the display surface side, and the "rear side" means the backlight unit side. Further, the "front" means the normal direction with respect to the display surface, and the "front contrast (CR)" means the contrast calculated from the white brightness and the black brightness measured in the normal direction of the display surface. ..

The "phase difference layer" means a region (phase difference region) located between the liquid crystal cell and the polarizer, and the magnitude of the retardation does not matter. If a pressure-sensitive adhesive layer is used to bond the retardation layer to the liquid crystal cell or polarizer, the pressure-sensitive adhesive layer is not part of the retardation layer.
The "phase difference layer" can be an A plate or a C plate. "A plate" and "C plate" are defined as follows.
There are two types of A-plates, a positive A-plate (positive A-plate) and a negative A-plate (negative A-plate). When the refractive index in the direction of maximum) is nx, the refractive index in the direction orthogonal to the slow axis in the plane and the plane is ny, and the refractive index in the thickness direction is nz, the positive A plate is given by the formula (A1). The negative A plate satisfies the relation of the formula (A2). The positive A plate shows a positive value for Rth, and the negative A plate shows a negative value for Rth.
Equation (A1) nx> ny≈nz
Equation (A2) ny <nx≈nz
The "≈" in the above formulas (A1) and (A2) includes not only the case where they are completely the same but also the case where they are substantially the same. Regarding "substantially the same", for example, when (ny-nz) x d (where d is the film thickness of the retardation layer) is -10 to 10 nm, preferably -5 to 5 nm, "ny" is also used. It is included in "≈ nz", and when (nx-nz) x d is -10 to 10 nm, preferably -5 to 5 nm, it is also included in "nx ≈ nz".
There are two types of C plates, a positive C plate (positive C plate) and a negative C plate (negative C plate). The positive C plate satisfies the relationship of the formula (C1), and the negative C plate. Satisfies the relationship of equation (C2). The positive C plate shows a negative value of Rth, and the negative C plate shows a positive value of Rth.
Equation (C1) nz> nx≈ny
Equation (C2) nz <nx≈ny
The “≈” in the above equations (C1) and (C2) includes not only the case where they are completely the same but also the case where they are substantially the same. Regarding "substantially the same", for example, when (nx-ny) x d (where d is the thickness of the retardation layer) is 0 to 10 nm, preferably 0 to 5 nm, "nx ≈ ny". include.

Next, the liquid crystal display device according to one aspect of the present invention will be described in more detail.

<Configuration of liquid crystal display device>
FIG. 1 is a schematic cross-sectional view showing an example of the configuration of a liquid crystal display device. The liquid crystal display device shown in FIG. 1 includes a liquid crystal panel including a rear side polarizing plate PL1, a liquid crystal cell LC, and a front side polarizing plate PL2, and a backlight unit 28. Specifically, the liquid crystal display device shown in FIG. 1 includes a front-side polarizer 26, a rear-side polarizer 24, a liquid crystal cell LC located between the front-side polarizer 26 and the rear-side polarizer 24, and a liquid crystal cell LC and a front. A liquid crystal panel having a front side retardation layer 22 located between the side polarizer 26 and a rear side retardation layer 20 located between the liquid crystal cell LC and the rear side polarizer 20, and a backlight unit 28. including. One or more members (for example, an adhesive layer) not shown in FIG. 1 may be included at arbitrary positions. The front side retardation layer 22 and the rear side retardation layer 20 have a retardation that contributes to viewing angle compensation. The front side retardation layer 22 and the rear side retardation layer 20 can include one or more optically anisotropic layers, and may also include two or more layers.

The liquid crystal cell LC is a VA type liquid crystal cell and has a liquid crystal layer 10 and a pair of substrates sandwiching the liquid crystal layer 10, that is, a front side substrate 18 and a rear side substrate 16, and the rear side substrate 16 and the liquid crystal layer 10 An array member 14 having a color filter layer 12 and a black matrix for partitioning pixels is provided between the two. The rear side substrate 16, the array member 14, and the color filter layer 12 constitute a COA (color filter on array) substrate. Such a structure in which the color filter is located on the active matrix substrate is called a COA (color filter on array) structure. In the liquid crystal display device shown in FIG. 1, a COA substrate is arranged between the liquid crystal layer 10 and the rear side retardation layer 20. That is, the liquid crystal cell LC has the COA substrate on the rear side. Known techniques can be applied to the mode of the VA liquid crystal display and the details of the COA substrate.

<Equation 1>
The liquid crystal display device has a polar angle of 0 ° in the front, an azimuth of 0 ° in the right direction, an azimuth of 180 ° in the left direction, and an azimuth of x and a polar angle of y when L (x, y) is displayed in black. When the amount of light leakage is taken as the following formula 1:
L1 (φ, 60) <L (0,60) + L (180,60)
To be satisfied. Here, L1 is the amount of light leakage when the azimuth angle is φ and the polar angle is 60 °, and φ is the range of -30 to 30 ° and the range of 150 to 210 °.
Regarding the azimuth, as shown in FIGS. 2A to 2C, when the direction perpendicular to the display screen is the polar angle of 0 °, the azimuth of 0 ° is the right direction and the azimuth of 180 ° at any polar angle (for example, 60 °). The ° direction means the left direction, the azimuth angle of 90 ° means the upward direction, and the azimuth angle of 270 ° means the downward direction.
Satisfying the above equation 1 means that the reduction of light leakage in the range of -30 to 30 ° and the azimuth in the range of 150 to 210 ° at the polar angle of 60 ° when displayed in black is in the right direction (azimuth angle of 0 °). And it means that it is prioritized over the reduction of light leakage in the left direction (azimuth angle 180 °). As a result, compared to the case where light leakage in all directions is reduced as much as possible when displaying black, for example, light leakage can be increased in the diagonally upward direction, but light leakage is small in the priority azimuth angle (azimuth angle in the above range). You can get the display.

Regarding the viewing angle performance of a VA type liquid crystal display device provided with a liquid crystal cell having a COA structure at the time of black display, when a plurality of people observe side by side on a large panel, the present inventors view the large panel from a passerby. It is currently mainly used to respond to requests to prioritize the viewing angle in the horizontal direction over the vertical direction, assuming applications where the viewing angle is limited to some extent, such as when posting in a passage so that it can be seen. We tried to improve the left-right viewing angle performance by arranging the same retardation film on the front side and the rear side. However, although it was possible to reduce light leakage in the oblique direction by this method, slight light leakage occurs in the vicinity of the polar angle of 60 °, centered on the azimuth angles of 45 °, 135 °, 225 °, and 315 °. Since light leakage cannot be sufficiently reduced even if the phase difference is adjusted, the observer may notice light leakage when the observation direction is slightly shifted up and down from the left-right direction, which increases the left-right viewing azimuth. Turned out to be limited.
Therefore, the present inventors have further studied, and if the phase difference is appropriately adjusted by using a phase difference layer having different phase differences between the rear side and the front side, the directional angle at which light leakage occurs can be moved. The light leakage that occurred in the 45 ° and 135 ° directions should be moved in the 90 ° direction (upward), and the light leakage that occurred in the 225 ° and 315 ° directions should be moved in the 270 ° direction (downward). It was found that this makes it possible to expand the left-right viewing direction angle.
In the method of arranging the phase difference layers having different phase differences between the rear side and the front side, a large phase difference is shared by the phase difference layer arranged on one side, and the phase difference layer on the other side has a low phase difference. There is a method using an inexpensive general-purpose difference film. However, in this case, although it was possible to increase the front CR by arranging a retardation layer having a large phase difference on the front side and arranging a retardation layer having a low retardation on the rear side, it is still in the left-right direction. There was a limit to the expansion of the viewing azimuth. Therefore, the present inventors have studied to improve the viewing angle by combining the retardation layer 1 and the retardation layer 2, which will be described in detail later, as the retardation layer. At this time, the phase difference condition is not a phase difference condition that can reduce light leakage in all directions at the time of black display as much as possible, but a phase difference condition that gives priority to the left and right viewing azimuths and reduces light leakage, that is, a polar angle of 60 °. Equation 1 was satisfied by selecting a phase difference condition in which light leakage at azimuth angles of −30 ° to 30 ° and 150 ° to 210 ° was preferentially reduced. As a result, in a VA type liquid crystal display device equipped with a liquid crystal cell having a COA structure, it has become possible to improve the front CR and the black display performance in the left-right direction (specifically, enlarge the left-right viewing azimuth angle). ..

<Phase difference layer>
The liquid crystal display device includes a retardation layer 1 and a retardation layer 2. The retardation layer 1 is included in at least the front side retardation layer, preferably is included in the front side retardation layer, and is not included in the rear side retardation layer. The retardation layer 2 is included in the front side retardation layer and / or the rear side retardation layer, preferably is included in the rear side retardation layer, and is not included in the front side retardation layer.

In the retardation layer 1, the in-plane retardation Re (550) measured at a wavelength of 550 nm is less than 20 nm (Re (550) <20 nm), and it is preferable that Re (550) <10 nm. The retardation layer 1 is preferably a C plate. The C plate can play a role of optically compensating for the phase difference when the liquid crystal cell is viewed from an angle when the liquid crystal cell is displayed in black. The thickness direction retardation Rth of the C plate is the thickness direction retardation Δnd (λ) (d [nm] of the liquid crystal cell), the thickness of the liquid crystal layer constituting the liquid crystal cell, and Δn (λ) is the wavelength (λ) of this liquid crystal layer. ), It is preferable to determine it according to (Δnd (λ) is the product of Δn (λ) and d), and Δnd (550) is usually set to about 280 to 350 nm. NS. From this point, the thickness direction retardation Rth (550) measured at the wavelength of 550 nm of the retardation layer 1 is 200 nm or more and 270 nm or less (200 ≦ Rth (550) ≦ 270 nm). Further, since the wavelength dependence of the phase difference of the liquid crystal cell is often forward dispersion in which the phase difference becomes smaller as the wavelength becomes longer, the wavelength dependence of the phase difference [nm] of the C plate is also in order. Dispersibility is preferred. However, it is not limited to this.

In the retardation layer 2, the in-plane retardation Re (550) measured at a wavelength of 550 nm is 130 nm or more and 155 nm or less, the thickness direction retardation Rth (550) measured at a wavelength of 550 nm is 55 nm or more and 90 nm or less, and the wavelength is 450 nm. The in-plane phase difference Re (450) measured in, the in-plane phase difference Re (550) measured at a wavelength of 550 nm, and the in-plane phase difference Re (650) measured at a wavelength of 650 nm are "Re (450) ≤ Re (550). ) ≤ Re (650) "is satisfied. The Re (550) of the retardation layer 2 is preferably 135 nm or more and 150 nm or less, and the thickness direction retardation Rth (550) of the retardation layer 2 is preferably 57 nm or more and 87 nm or less. The retardation layer 2 is preferably an A plate. The A plate optically compensates for the fact that the absorption axes of the rear-side polarizing plate and the front-side polarizing plate are not orthogonal to each other when viewed from an angle and cause light leakage, thereby preventing light leakage during black display of the liquid crystal display device. Can play a role in reducing. The wavelength dependence of the phase difference of the A plate preferably has a reverse dispersibility in which the phase difference [nm] increases as the wavelength becomes longer. However, it is not limited to this. Placing the C plate on the front side and the A plate on the rear side across the liquid crystal cell is preferable from the viewpoint of further improving the front CR and further improving the black display performance in the left-right direction. The front CR can be further improved by arranging the A plate on the front side as well as the C plate (however, the A plate is arranged closer to the front side polarizer than the C plate). On the other hand, it is preferable to arrange the C plate on the front side and the A plate on the rear side via the liquid crystal cell from the viewpoint of further improving the black display performance in the left-right direction.

The retardation layer 1 and the retardation layer 2 include an optically anisotropic layer containing a polymerizable liquid crystal compound. For example, the retardation layer 1 and the retardation layer 2 can include a support, an alignment film, and an optically anisotropic layer in this order. While the thickness of a general retardation film is several tens of μm, by using a polymerizable liquid crystal compound, for example, an optically anisotropic layer having a thickness of several μm can be obtained. The thin thickness of the optically anisotropic layer is preferable from the viewpoint of thinning the retardation layer, thinning the liquid crystal panel, and thinning the liquid crystal display device. The optically anisotropic layer may be produced by forming an alignment film on the support and then applying a liquid containing a polymerizable liquid crystal compound, or further peeling the optically anisotropic layer from the support to obtain polarized light. It may be attached to the child or the liquid crystal cell via an adhesive layer. Further, an alignment film may be formed on the polarizer as necessary, and then a liquid containing a polymerizable liquid crystal compound may be applied to prepare an optically anisotropic layer. The latter tends to give a thinner optically anisotropic layer.

The optically anisotropic layer produced by using the polymerizable liquid crystal compound can be a cured layer of a polymerizable composition containing the polymerizable liquid crystal compound. Specifically, for example, an optically anisotropic layer obtained by forming a low-molecular-weight liquid crystal compound in a nematic orientation in a liquid crystal state and then immobilizing it by photocrosslinking or thermal cross-linking, and a polymer liquid crystal compound formed in a nematic orientation in a liquid crystal state. After that, an optically anisotropic layer obtained by immobilizing the orientation by cooling can be mentioned. The optically anisotropic layer is, for example, a layer formed by fixing a liquid crystal compound by polymerization or the like, and usually does not exhibit liquid crystallinity after forming the layer. Further, the "optically anisotropic layer containing a polymerizable liquid crystal compound" is an optically anisotropic layer formed by using the polymerizable liquid crystal compound, and in the formed layer, the polymerizable liquid crystal compound is , It is usual that some or all of the polymerizable groups contained in this compound show little or little polymerizable after being subjected to the polymerization reaction.

Generally, a liquid crystal compound can be classified into a rod-shaped type (rod-shaped liquid crystal compound) and a disk-shaped type (discotic liquid crystal compound, disk-shaped liquid crystal compound) according to its shape. In addition, there are small molecule and polymer types, respectively. A polymer generally refers to a polymer having a degree of polymerization of 100 or more (see Polymer Physics / Phase Transition Dynamics, Masao Doi, p. 2, Iwanami Shoten, 1992). Any liquid crystal compound can be used to form the optically anisotropic layer, and in one aspect, a discotic liquid crystal compound is preferable. Further, two or more kinds of rod-shaped liquid crystal compounds, two or more kinds of discotic liquid crystal compounds, or a mixture of a rod-shaped liquid crystal compound and a discotic liquid crystal compound may be used.
As the rod-shaped liquid crystal compound, for example, those described in claim 1 of JP-A No. 11-513019 and paragraphs [0026] to [0098] of JP-A-2005-289980 can be used, and the rod-shaped liquid crystal compound can be disk-shaped. As the liquid crystal compound, for example, those described in paragraphs [0020] to [0067] of JP-A-2007-108732 and paragraphs [0013] to [0108] of JP-A-2010-244038 can be used. .. However, it is not limited to these.

It is preferable to form the optically anisotropic layer using a liquid crystal compound having a polymerizable group (polymerizable liquid crystal compound) because the temperature change and / or the humidity change of the optical characteristics can be reduced. Further, as described above, it is preferable to use a polymerizable liquid crystal compound from the viewpoint of thinning the retardation layer. In one aspect, the optically anisotropic layer is preferably a liquid crystal layer having a thickness of 5.0 μm or less (for example, 1.0 to 5.0 μm). Here, the "liquid crystal layer" is a layer formed by using a liquid crystal compound, and as described above, it usually does not exhibit liquid crystal properties after being formed into a layer. The liquid crystal compound used to form the optically anisotropic layer may be a mixture of two or more kinds, in which case bifunctional or higher polymerization in which at least one has two or more polymerizable groups in one molecule. It is preferably a sex liquid crystal compound. The type of the polymerizable group is not particularly limited, and a functional group capable of an addition polymerization reaction is preferable, and specifically, a polymerizable ethylenically unsaturated group or a ring-polymerizable group is preferable. More specifically, a (meth) acryloyl group, a vinyl group, a styryl group, an allyl group and the like are preferably mentioned, and a (meth) acryloyl group is more preferable. The (meth) acryloyl group is a concept that includes both a meta-acryloyl group and an acryloyl group.

In one aspect, the front side retardation layer and the rear side retardation layer preferably do not have a scattering function. "No scattering function" can mean, for example, that the haze value of the polarizing plate including the retardation layer is 0.2% or less, preferably 0.1% or less. can. It is preferable to use a polarizing plate whose retardation layer does not have a scattering function from the viewpoint of further improving the front CR of the liquid crystal display device. In one aspect, by applying such a polarizing plate, it is possible to improve the frontal CR ratio described later to, for example, more than 110%, preferably 115% or more in the liquid crystal display device.

Also, in one aspect, the retardation layer 1 and the retardation layer 2 may not include a support and / or an alignment film. The retardation layer that does not include the support and / or the alignment film includes, for example, the support, the alignment film, and the optically anisotropic layer after forming the optically anisotropic layer on the alignment film provided on the support. It can be produced by peeling the support from the laminate or peeling the support and the alignment film. Alternatively, by providing an alignment film on the polarizer and forming an optically anisotropic layer on the alignment film, a retardation layer that does not include a support can be obtained. As the support, a polymer film is usually used. The fact that the retardation layer does not include a support can contribute to further improvement of the front contrast.

In one aspect, a diffusion layer can be provided on the front surface of the liquid crystal panel, for example, the surface of the front polarizing plate. Further, in order to further expand the left-right viewing azimuth, instead of suppressing the light emission in the vertical viewing direction of the backlight unit itself, a condensing type backlight unit with enhanced light emission in the front and left-right viewing directions may be used in combination. .. As the condensing backlight unit, a prism sheet, a louver film (for example, PF12.1WS (manufactured by 3M)) or the like is used to suppress the brightness of light in the vertical direction in the front and left-right viewing directions. A backlight unit with increased brightness can be used. A backlight unit that suppresses light emission in the diagonal direction and emits light intensively in the front direction may be used regardless of the top, bottom, left, or right. When these condensing backlight units are used, a viewing direction with low brightness is generated, but light can be scattered by the diffusion layer on the surface of the front polarizing plate, so that the left-right viewing azimuth can be further widened. Can be done. As the diffusing layer, a known layer or film having a function of diffusing light can be used. Further, as the backlight unit, a backlight unit having a half-value half width of the emission angle distribution in the vertical direction within 30 ° can be used, and it is preferable to use a backlight unit within 25 °, and a backlight within 20 °. It is more preferable to use a unit. The emission angle distribution of the backlight unit means 1/2 of the difference between the two tilt angles, which is half of the maximum value, with the tilt angle at which the brightness value of the backlight unit is the maximum value. The half-value and half-width of the emission angle distribution in the vertical direction of the backlight unit can be obtained by the following method. With respect to the front of the backlight unit (the direction in which the polar angle is 0 °), the azimuth angle is 90 °, that is, the polar angle from 80 ° to 0 ° in the upward direction, and the azimuth angle is 270 °, that is, the polar angle is 0 in the downward direction. From ° to 80 °, measure the brightness of the center of the backlight unit at 5 ° intervals. Next, the polar angle at which the brightness value is maximized and the polar angle at which the brightness value is 1/2 of the maximum value of the brightness value are examined. For example, at both the azimuth angle of 90 ° and the azimuth angle of 270 °, when the polar angle is 25 ° and the luminance value is half of the maximum value, the half width is 25 °.

Hereinafter, the present invention will be described based on examples. However, the present invention is not limited to the embodiments shown in the examples. As the pressure-sensitive adhesive described below, SK-2057 manufactured by Soken Chemical Co., Ltd. was used.

(1) Preparation of Polarizers A and B with Single-sided Protective Film A polyvinyl alcohol (PVA) film having a thickness of 80 μm is immersed in an aqueous iodine solution (liquid temperature 30 ° C.) having an iodine concentration of 0.05% by mass for 60 seconds for dyeing. Then, while immersed in a boric acid aqueous solution having a boric acid concentration of 4% by mass for 60 seconds, the film was vertically stretched to 5 times the original length and then dried for 4 minutes (atmosphere temperature 50 ° C.) to make the thickness. A 20 μm polarizer was obtained.
A commercially available cellulose acylate film "TD80UL" (manufactured by Fujifilm Co., Ltd.) is prepared, immersed in a sodium hydroxide aqueous solution at a sodium hydroxide concentration of 1.5 mol / liter and a liquid temperature of 55 ° C., and then water is sufficient. Sodium hydroxide was washed away. Then, it was immersed in a dilute sulfuric acid aqueous solution having a sulfuric acid concentration of 0.005 mol / liter and a liquid temperature of 35 ° C. for 1 minute, and then immersed in water to thoroughly wash away the dilute sulfuric acid aqueous solution. Finally, the cellulose acylate-based film was sufficiently dried (atmospheric temperature 120 ° C.) to prepare a polarizer protective film A.
Polarizer A with a single-sided protective film, in which the polarizer protective film A prepared above is bonded to one side of the polarizer produced above with a polyvinyl alcohol-based adhesive, and the polarizer protective film A and the polarizer are laminated. Was produced.
Next, a commercially available cellulose acylate film "CVLX" (manufactured by Fujifilm Co., Ltd.) having a diffusion layer (light scattering function layer) on the surface was prepared, and the liquid temperature was 55 at a sodium hydroxide concentration of 1.5 mol / liter. After immersing in an aqueous solution of sodium hydroxide at ° C, the sodium hydroxide was thoroughly washed away with water. Then, it was immersed in a dilute sulfuric acid aqueous solution having a sulfuric acid concentration of 0.005 mol / liter and a liquid temperature of 35 ° C. for 1 minute, and then immersed in water to thoroughly wash away the dilute sulfuric acid aqueous solution. Finally, the cellulose acylate-based film was sufficiently dried (atmospheric temperature 120 ° C.) to prepare a polarizer protective film B.
A polarizing plate B with a single-sided protective film, in which the polarizer protective film B prepared above is bonded to one side of the polarizer produced above with a polyvinyl alcohol-based adhesive, and the polarizer protective film B and the polarizer are laminated. Was produced.

(2) Preparation of polarizing plates 1 and 5 (alkaline saponification treatment)
A commercially available cellulose acylate film ZRF25 (manufactured by Fujifilm Co., Ltd.) is passed through a dielectric heating roll having a temperature of 60 ° C. to raise the film surface temperature to 40 ° C., and then the band surface of the film has the composition shown below. The alkaline solution of Noritake Co., Ltd. was applied at a coating amount of 14 ml / m ² using a bar coater, and was conveyed for 10 seconds under a steam-type far-infrared heater manufactured by Noritake Co., Ltd. Limited, which was heated to 110 ° C. Subsequently, pure water was subsequently applied at a coating amount of 3 ml / m ² using the same bar coater. Next, after repeating washing with water with a fountain coater and draining with an air knife three times, the product was transported to a drying zone having an atmospheric temperature of 70 ° C. for 10 seconds to be dried, and an alkali saponified ZRF25 was prepared.

Alkaline solution composition ──────────────────────────────────
・ Potassium hydroxide 4.7 parts by mass ・ Water 15.8 parts by mass ・ Isopropanol 63.7 parts by mass ・ Surfactant SF-1: C ₁₄ H ₂₉ O (CH ₂ CH ₂ O) ₂₀ H
1.0 part by mass, propylene glycol 14.8 parts by mass ──────────────────────────────────

(Formation of alignment film)
On the ZRF25 (support) subjected to the above alkali saponification treatment, a coating liquid having the following composition was applied with a wire bar coater of # 14 at a coating amount of 24 ml / m ² . It was dried with warm air at 60 ° C. for 60 seconds and further with warm air at 90 ° C. for 150 seconds.

(Formation of optically anisotropic layer C1 containing a discotic liquid crystal compound (polymerizable liquid crystal compound))
On the alignment film formed on the ZRF25 subjected to the above alkali saponification treatment, a coating liquid containing a discotic liquid crystal (discotic liquid crystal compound) having the following composition was continuously applied for 50 m with a # 3 wire bar.
(Composition of coating liquid for discotic liquid crystal layer)
The following discotic liquid crystal compound (B) 26.2% by mass
The following discotic liquid crystal compound (C) 6.6% by mass
Compound I-6 0.15% by mass
Ethylene oxide modified trimethylolpropane triacrylate (V # 360, manufactured by Osaka Organic Chemical Co., Ltd.) 3.2% by mass
Sensitizer (Kayacure DETX, manufactured by Nippon Kayaku Co., Ltd.) 0.4% by mass
Photopolymerization initiator (Irgacure 907, manufactured by Ciba Geigy) 1.1% by mass
Methyl ethyl ketone 62.0% by mass

After the above coating liquid was applied, it was subsequently heated and dried in a drying zone having an atmospheric temperature of 130 ° C. for 2 minutes to orient the discotic liquid crystal compound. Next, the discotic liquid crystal compound was polymerized by UV irradiation for 4 seconds using a 120 W / cm high-pressure mercury lamp at 80 ° C. in the UV irradiation zone. Then, it was allowed to cool to room temperature and wound up. The prepared retardation layer C1 having the optically anisotropic layer C1 (optical anisotropic layer C1, laminated body of alignment film and support) was subjected to an automatic birefringence meter (KOBRA-21ADH, When the measurement was performed using Oji Measuring Instruments Co., Ltd., it was a negative C plate that optically showed negative refractive index anisotropy, and Re (550) = 0 nm and Rth (550) = 232 nm. .. The discotic liquid crystal compound of the optically anisotropic layer C1 was horizontally oriented in the range of ± 1 °. The thickness of the optically anisotropic layer C1 was 2.0 μm.
Using an adhesive, the support (ZRF25 subjected to alkali saponification treatment), the alignment film, and the optically anisotropic layer C side of the laminate of the optically anisotropic layer C prepared as described above were subjected to (1). The prepared polarizing plate A with a single-sided protective film was bonded so as to face the polarizer side. In this way, the polarizing plate 1 in which the polarizing element protective film, the polarizing element, the pressure-sensitive adhesive, the optically anisotropic layer C, the alignment film, and the support were laminated in this order was produced.
Further, the optically anisotropic layer C side of the support, the alignment film, and the laminated body of the optically anisotropic layer C prepared as described above is subjected to an adhesive (SK-2057, manufactured by Soken Kagaku Co., Ltd.). The polarizing plate B with a single-sided protective film produced in (1) was bonded so as to face the polarizer side. In this way, a polarizing plate 5 in which a polarizing element protective film (with a diffusion layer), a polarizer, an adhesive, an optically anisotropic layer C, an alignment film, and a support were laminated in this order was produced.

(3) Preparation of Polarizing Plates 14 to 17 Using the same method as the preparation method for polarizing plate 1, except that the amount of methyl ethyl ketone was changed between 60 and 65% by mass in the composition of the coating liquid of the discotic liquid crystal layer. , Optically anisotropic layers C14 to C17 were prepared. The retardation layers C14 to C17 are a laminate of an optically anisotropic layer, an alignment film, and a support. The Rth (550) of the retardation layer C14 having the optically anisotropic layer C14 is 222 nm, the Rth (550) of the retardation layer C15 having the optically anisotropic layer C15 is 227 nm, and the retardation having the optically anisotropic layer C16. The Rth (550) of the layer C16 was 227 nm, and the Rth (550) of the retardation layer C17 having the optically anisotropic layer C17 was 242 nm. The retardation layers C14 to C17 produced here are negative C plates that optically exhibit negative refractive index anisotropy, Re (550) = 0 nm, and the thickness of each optically anisotropy layer is 2. It was 0.0 μm. Each of the retardation layers was bonded so that the optically anisotropic layer faced the polarizer side of the polarizing plate A with the single-sided protective film prepared in (1) using an adhesive. In this way, polarizing plates 14 to 17 in which a polarizing element protective film, a polarizing element, an adhesive, an optically anisotropic layer, an alignment film, and a support were laminated in this order were produced.

(4) Preparation of Polarizing Plate 2 After performing an alkali saponification treatment on the band surface of ZRF25 (manufactured by Fujifilm Co., Ltd.) in the same manner as the polarizing plate 1, refer to the description of Example 3 of JP2012-155308A. , A coating liquid for a photoalignment film was prepared, and the ZRF25 was coated on the band surface subjected to the alkali saponification treatment with a wire bar. The ZRF25 with a photoalignment film was prepared by drying with warm air at 60 ° C. for 60 seconds.
The prepared ZRF25 with a photoalignment film was irradiated with ultraviolet rays in the atmosphere using an ultrahigh pressure mercury lamp. ^{The illuminance of the ultraviolet rays used at this time was set to 5 mJ / cm 2 in} the UV-A region (ultraviolet A wave, integration of wavelengths of 380 nm to 320 nm).
After applying a coating liquid containing the same discotic liquid crystal (disk-shaped liquid crystal compound) used for producing the polarizing plate 1, the discotic liquid crystal compound is subsequently heated and dried in a drying zone having an atmospheric temperature of 130 ° C. for 2 minutes. Was oriented. Next, in the UV irradiation zone, the discotic liquid crystal compound was polymerized by UV irradiation for 4 seconds using a high-pressure mercury lamp at an atmospheric temperature of 80 ° C. and 120 W / cm. Then, it was allowed to cool to room temperature and wound up. In this way, a laminated body of the optically anisotropic layer C2, the alignment film, and the support was produced.
The laminate prepared as described above was bonded using an adhesive so that the optically anisotropic layer C2 side faced the polarizer side of the polarizing element A with the single-sided protective film prepared in (1). Then, the support and the alignment film were peeled off.
In this way, a polarizing plate 2 in which a polarizing element protective film, a polarizer, an adhesive, and an optically anisotropic layer C2 (phase difference layer C2) were laminated in this order was produced. The retardation layer C2 is a negative C plate that optically exhibits negative refractive index anisotropy, Re (550) = 0 nm, Rth (550) = 232 nm, and the thickness of the optically anisotropic layer C2 is 2.0 μm. Met. The discotic liquid crystal compound of the optically anisotropic layer C2 was horizontally oriented in the range of ± 1 °.

(5) Preparation of Polarizing Plate 3 After performing an alkali saponification treatment on the band surface of ZRF25 (manufactured by Fujifilm Co., Ltd.) in the same manner as the polarizing plate 1, refer to the description of Example 3 of JP2012-155308A. , A coating liquid for a photoalignment film was prepared, and the ZRF25 was coated on the band surface subjected to the alkali saponification treatment with a wire bar. The ZRF25 with a photoalignment film was prepared by drying with warm air at 60 ° C. for 60 seconds.
The prepared ZRF25 with a photoalignment film was irradiated with ultraviolet rays in the atmosphere using an ultrahigh pressure mercury lamp. At this time, a wire grid polarizer (ProFlux PPL02, manufactured by Moxtek) was set so as to be parallel to the surface of the photoalignment film and exposed to light alignment processing. ^{The illuminance of the ultraviolet rays used at this time was 10 mJ / cm 2 in} the UV-A region (ultraviolet A wave, integration of wavelengths of 380 nm to 320 nm).
Subsequently, the following coating liquid for forming the optically anisotropic layer A was prepared.
――――――――――――――――――――――――――――――――――
Composition of coating liquid for forming optically anisotropic layer A ――――――――――――――――――――――――――――――――――
The following polymerizable compound X-1 20.00 parts by mass The following liquid crystal compound L-1 40.00 parts by mass The following liquid crystal compound L-2 40.00 parts by mass The following polymerization initiator S-1 3.00 parts by mass The following compound A- 1 0.10 parts by mass Leveling agent (Compound T-1 below) 0.10 parts by mass Methyl ethyl ketone (solvent) 200.00 parts by mass Cyclopentanone (solvent) 200.00 parts by mass ―――――――――― ――――――――――――――――――――――――

Next, a coating liquid for forming an optically anisotropic layer A was applied onto the photoalignment-treated surface using a bar coater. After aging by heating at a film surface temperature of 100 ° C. for 20 seconds and cooling to 55 ° C., an air-cooled metal halide lamp (manufactured by Eye Graphics Co., Ltd.) is used to irradiate ultraviolet rays of ^{300 mJ / cm 2 and its orientation.} By immobilizing the state, ZRF25 with an optically anisotropic layer A was formed. The optically anisotropic layer A was bonded using an adhesive so that the surface A surface of the polarizing plate A with a single-sided protective film produced in (1) faces the polarizer side. In this way, the polarizing plate 3 in which the polarizer protective film, the polarizer, the optically anisotropic layer A, the alignment film, and the support were arranged in this order was produced. The formed optically anisotropic layer A was perpendicular to the absorption axis of the polarizing plate in the slow phase axis direction (that is, the liquid crystal compound was oriented perpendicular to the absorption axis of the polarizing plate).
The polarizing plate 3 has an optically anisotropic layer A, a retardation layer A which is a laminated body of an alignment film and a support. The retardation angle dependence of Re and the tilt angle of the optical axis of the retardation layer A were measured using an automatic birefringence meter (KOBRA-21ADH, manufactured by Oji Measuring Instruments Co., Ltd.) before bonding with the polarizer. However, Re (550) is 143 nm, Rth (550) is 72 nm, Re (550) / Re (450) is 1.12, Re (650) / Re (550) is 1.01, and Re (450) is 128 nm. , Re (650) was 144 nm, the tilt angle of the optical axis was 0 °, it was a positive A plate showing optically positive anisotropy, and the liquid crystal compound was homogenically oriented. As described above, the retardation layer A satisfies "Re (450) ≤ Re (550) ≤ Re (650)". The thickness of the optically anisotropic layer A was 2.5 μm.

(6) Preparation of Polarizing Plates 31 to 34 Using the same method as for forming the optically anisotropic layer A, except that the coating amount of the coating liquid for forming the optically anisotropic layer A was changed.
Phase difference layer A31 with Re (550) of 133 nm and Rth (550) of 67 nm,
Phase difference layer A32 with Re (550) of 138 nm and Rth (550) of 69 nm,
Phase difference layer A33, where Re (550) is 148 nm and Rth (550) is 74 nm.
Phase difference layer A34, where Re (550) is 153 nm and Rth (550) is 77 nm.
Was formed. Except for the above points, the polarizing plate 31 having the retardation layer A31, the polarizing plate 32 having the retardation layer A32, the polarizing plate 33 having the retardation layer A33, and the retardation layer A34 are the same as the method for producing the polarizing plate 3. Each of the polarizing plates 34 having the above was prepared. The retardation layers A31 to A34 are a laminate of an optically anisotropic layer, an alignment film, and a support, and are positive A plates showing optically positive anisotropy, and are Re (550) / Re (450). Was 1.12, Re (650) / Re (550) was 1.01, the tilt angle of the optical axis was 0 °, and the liquid crystal compound was anisotropically oriented. Re (450) and Re (650) of the retardation layers A31 to A34 are as follows, and both satisfy "Re (450) ≤ Re (550) ≤ Re (650)".
Phase difference layer A31: Re (450) = 119 nm, Re (550) = 133 nm, Re (650) = 134 nm
Phase difference layer A32: Re (450) = 123 nm, Re (550) = 138 nm, Re (650) = 139 nm
Phase difference layer A33: Re (450) = 132 nm, Re (550) = 148 nm, Re (650) = 149 nm
Phase difference layer A34: Re (450) = 137 nm, Re (550) = 153 nm, Re (650) = 155 nm
The thickness of the optically anisotropic layer contained in the retardation layers A31 to A34 was as follows.
Optically anisotropic layer contained in the retardation layer A31: 2.3 μm
Optically anisotropic layer contained in the retardation layer A32: 2.4 μm
Optically anisotropic layer contained in the retardation layer A33: 2.7 μm
Optically anisotropic layer contained in the retardation layer A34: 2.9 μm
In the production of the polarizing plates 31 to 34, as in the production of the polarizing plate 3, the surface on the optically anisotropic layer side is adhered so as to face the polarizer side of the polarizing plate A with the single-sided protective film produced in (1). They were bonded together using an agent. In this way, polarizing plates 31 to 34 in which the polarizer protective film, the polarizer, the optically anisotropic layer, the photoalignment film, and the support were arranged in this order were produced.

(7) Fabrication of polarizing plate 4 (fabrication of a polarizer with a photoalignment film)
A coating liquid for a photoalignment film was prepared with reference to the description of Example 3 of JP2012-155308A, and a wire bar was formed on the polarizing plate side surface of the polarizing plate A with a single-sided protective film prepared in (1) above. Was applied with. It was dried with warm air at 60 ° C. for 60 seconds to prepare a polarizer with a photoalignment film.
The prepared polarizer with a photoalignment film was irradiated with ultraviolet rays in the atmosphere using an ultrahigh pressure mercury lamp. At this time, a wire grid polarizer (ProFlux PPL02, manufactured by Moxtek) was set so as to be parallel to the surface of the photoalignment film and exposed to light alignment processing. ^{The illuminance of the ultraviolet rays used at this time was 10 mJ / cm 2 in} the UV-A region (ultraviolet A wave, integration of wavelengths of 380 nm to 320 nm).
Next, a liquid having the same composition as the coating liquid for forming the optically anisotropic layer A used when producing the polarizing plate 3 was applied onto the photoalignment-treated surface using a bar coater. It is aged by heating at a film surface temperature of 100 ° C. for 20 seconds, cooled to 55 ° C., and then irradiated with ultraviolet rays of ^{300 mJ / cm 2 using an air-cooled metal halide lamp (manufactured by Eye Graphics Co., Ltd.) under air, and its orientation.} The polarizing plate 4 was formed by immobilizing the state. The obtained polarizing plate 4 has a polarizer protective film, a polarizer, an alignment film, and an optically anisotropic layer A4 arranged in this order. The polarizing plate 4 includes a retardation layer A4 which is a laminate of an alignment film and an optically anisotropic layer A4. The retardation layer A4 has Re (550) of 143 nm, Rth (550) of 72 nm, Re (550) / Re (450) of 1.12, Re (650) / Re (550) of 1.01, and Re ( 450) is 128 nm, Re (650) is 144 nm, the tilt angle of the optical axis is 0 °, it is a positive A plate showing optically positive anisotropy, the thickness is 2.5 μm, and the liquid crystal compound is Homogeneous orientation.

(8) Preparation of Polarizing Plate 6 The polarizing plate 4 produced in the above (7) is the ZRF25, the alignment film, and the optically anisotropic layer C1 side of the optically anisotropic layer C1 prepared in the middle of the above (2). It was bonded to the optically anisotropic layer A4 side of the above using an adhesive. Then, by peeling off the ZRF25 and the alignment film, a polarizing plate 6 in which a polarizer protective film, a polarizer, an alignment film, an optically anisotropic layer A4, an adhesive and an optically anisotropic layer C1 are laminated in this order is produced. bottom. The polarizing plate 6 includes a retardation layer made of an optically anisotropic layer C1 and a retardation layer which is a laminate of an alignment film and an optically anisotropic layer A4. The retardation layer made of the optically anisotropic layer C1 was a negative C plate that optically exhibited negative refractive index anisotropy, and had Re (550) = 0 nm and Rth (550) = 232 nm. The discotic liquid crystal compound of the optically anisotropic layer C1 was horizontally oriented in the range of ± 1 °. The thickness of the optically anisotropic layer C1 was 2.0 μm.
The retardation layer, which is a laminate of the alignment film and the optically anisotropic layer A4, has Re (550) of 143 nm, Rth (550) of 72 nm, Re (550) / Re (450) of 1.12, and Re ( 650) / Re (550) is 1.01, the tilt angle of the optical axis is 0 °, it is a positive A plate showing optically positive anisotropy, the thickness is 2.5 μm, and the liquid crystal compound is It is an anisotropic orientation.

(9) Preparation of Polarizing Plate 7 A commercially available cellulose acylate film ZRF25 (manufactured by Fujifilm Co., Ltd.) is used, and an adhesive is used on the side of the polarizing plate A with a single-sided protective film prepared in (1) facing the polarizer. The polarizing plate 7 was produced by laminating the polarizing plate 7. At this time, the MD (machine direction) of the ZRF25 was made to coincide with the absorption axis of the polarizer of the polarizing plate A with the single-sided protective film.
In the polarizing plate 7, ZRF25 was a retardation layer, and its Re (550) was 1 nm and Rth (550) was 0 nm.

(10) Preparation of polarizing plate 8 (preparation of cellulose acylate)
Cellulose acylate was synthesized by the methods described in JP-A-10-45804 and JP-A-08-231761, and the degree of substitution thereof was measured. Specifically, sulfuric acid (7.8 parts by mass with respect to 100 parts by mass of cellulose) was added as a catalyst, carboxylic acid as a raw material for an acyl substituent was added, and an acylation reaction was carried out at 40 ° C. At this time, the type and degree of substitution of the acyl group were adjusted by adjusting the type and amount of the carboxylic acid. After acylation, aging was performed at 40 ° C. Further, the low molecular weight component of this cellulose acylate (cellulose acetate) was washed with acetone to remove it to obtain a cellulose acylate having an average acyl substitution degree of 2.43 and a cellulose acylate having an average acyl substitution degree of 2.81.

(Preparation of dope for core layer formation)
The following composition was put into a mixing tank and stirred to dissolve each component to prepare a cellulose acetate solution (hereinafter, also referred to as dope). The obtained dope was used as a core layer forming dope A1.
-Cellulose acetate prepared above (average acyl substitution degree 2.43)
122 parts by mass ・ Compound-1 below 4.9 parts by mass ・ Compound-2 below 2.8 parts by mass ・ Methylene chloride 548 parts by mass ・ Methanol 82 parts by mass Solid content concentration is 17% by mass, cellulose acetate concentration is 16.2 parts by mass %.

Compound-1
Ester oligomer consisting of the following dicarboxylic acid and diol

(Preparation of dope for skin layer formation)
The following composition was put into a mixing tank and stirred to dissolve each component to prepare a dope for a skin layer.
-Cellulose acetate prepared above (average acyl substitution degree 2.81)
87 parts by mass ・ Compound-1 3.5 parts by mass ・ Compound-2 2.0 parts by mass ・ Methylene chloride 455 parts by mass ・ Methanol 70 parts by mass Solid content concentration is 15% by mass, cellulose acetate concentration is 14.1 parts by mass %.

(Formation of cellulose acylate film)
(Hypersalivation)
The core layer forming dope and the skin layer forming dope prepared above were used and cast using a band caster. When casting the dope, it was cast from a casting die over a running endless band. The amount of residual solvent in the film on the band is set to d1 as the film thickness measured by a non-contact film thickness meter at an arbitrary time point, and the web on which d1 is measured is dried at 110 ° C. for 3 hours and then completely dried. The film thickness measured by the same method was taken as d2, and d1 and d2 were used for calculation based on the following equation.
Residual solvent amount = {(film thickness d1-completely dried film thickness d2 during drying) / completely dried film thickness d2} x 100%

(Drying method on the band)
In order to control the temperature after discharging both dope from the die, the band back surface temperature and the drying air temperature were controlled as follows. The band back surface temperature was controlled by setting the rotating roll to 9 ° C. and the temperature of the band back surface temperature control device to 15 ° C., and the drying air temperature was controlled by setting the temperature of the drying device on the band to 30 ° C. .. As a result, the film temperatures of 300% volatile content, 300 to 150% volatile content, and 150 to 100% volatile content from the die were controlled to 9 to 12 ° C, 12 to 18 ° C, and 18 to 22 ° C, respectively. Then, it was further dried and peeled off from the band with a solvent amount of about 20%. Then, in a tenter zone having an air supply temperature of 197 ° C., a cellulose acylate film was produced by stretching 1.34 times in the width direction while applying a tension of 50 N / m. At this time, the casting film thickness was adjusted so that the film thickness after stretching was 40 μm. This film was used as the film 8.

(Letteration)
Regarding the obtained film 8, Re and Rth at a wavelength of 550 nm were measured by the above-mentioned method using an automatic birefringence meter KOBRA-21ADH (manufactured by Oji Measuring Instruments Co., Ltd.). As a result, Re (550) = 50 nm and Rth (550). ) = 125 nm.
When Re and Rth at wavelengths of 450 nm, 550 nm, and 650 nm were determined using the same method as above, the Re and Rth of the film both increased as the wavelength became longer, showing reverse dispersibility.

(Preparation of polarizing plate)
Adhesive to the side of the polarizer A with a single-sided protective film facing the polarizer so that the MD (machine direction) of the film 8 produced above coincides with the absorption axis of the polarizer A with a single-sided protective film prepared in (1). The polarizing plate 8 was prepared by laminating with an agent.

(11) Preparation of polarizing plate 9 (cellulose acylate solution for low substitution layer)
The following composition was put into a mixing tank, and each component was dissolved by stirring while heating to prepare a cellulose acylate solution for a low substitution layer.
Cellulose acetate with a degree of substitution of 2.43 100 parts by mass Lettering expressing agent (2) 17.0 parts by mass Methylene chloride 361.8 parts by mass Methanol 54.1 parts by mass

(Cellulose acylate solution for high degree of 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 degree of substitution layer.
Cellulose acetate with a degree of substitution of 2.79 100.0 parts by mass Lettering agent (2) 11.0 parts by mass Silica particles with an average particle size of 16 nm (aerosil R972 manufactured by Aerosil Japan Co., Ltd.)
0.15 parts by mass Methylene chloride 395.0 parts by mass Methanol 59.0 parts by mass

The composition of the retardation expressing agent (2) is shown in the table below. In the table below, EG indicates ethylene glycol, PG indicates propylene glycol, TPA indicates terephthalic acid, and SA indicates succinic acid. The retardation expressing agent (2) is a non-phosphoric acid ester compound. The end of the retardation expressing agent (2) is sealed with an acetyl group.

(Preparation of cellulose acylate sample)
The cellulose acylate solution for a low degree of substitution layer is formed into a core layer having a film thickness of 114 μm, and the cellulose acylate solution for a high degree of substitution layer is formed into a skin A layer and a skin B layer having a film thickness of 2 μm. Each was spread. The obtained film was peeled off from the band, sandwiched between clips, and tentered at a temperature of 170 ° C. when the amount of residual solvent with respect to the total mass of the film was 20%. Then, the clip was removed from the film and dried at an atmospheric temperature of 130 ° C. for 20 minutes, and then laterally stretched at a stretching temperature of 180 ° C. in the width direction by 23% using a tenter to prepare a film. This film was used as the film 9. When measured using an automatic birefringence meter (KOBRA-21ADH, manufactured by Oji Measuring Instruments Co., Ltd.), Re (550) was 61 nm and Rth (550) was 208 nm at a wavelength of 550 nm of the film 9.
When Re and Rth at wavelengths of 450 nm, 550 nm, and 650 nm were determined using the same method as above, both Re and Rth of the film 9 showed inverse dispersibility that the longer the wavelength was, the larger the Re and Rth were. ..
The film 9 produced as described above is placed on the side of the polarizing plate A with a single-sided protective film facing the polarizer so that the slow axis is orthogonal to the absorption axis of the polarizing element A with a single-sided protective film produced in (1). A polarizing plate 9 was prepared by laminating with a pressure-sensitive adhesive.

(12) Preparation of Polarizing Plate 10 Polarized light with a single-sided protective film produced by MD (Machine Direction) in (1) using a commercially available cellulose acylate film (Fujitac TD80UL, manufactured by Fujifilm Co., Ltd.) using an adhesive. A polarizing plate 10 was prepared by laminating the polarizing element A with a single-sided protective film on the side facing the polarizer so as to coincide with the absorption axis of the child A. In the polarizing plate 10, the cellulose acylate film was a retardation layer, and its Re (550) was 3 nm and Rth (550) was 43 nm.

(13) Preparation of Polarizing Plates 11, 12, 13 By the method described in Example 1 of Patent No. 3648240, with a film A having Re (550) = 143 nm, Rth (550) = 72 nm, and a thickness of 85.5 μm. , Re (550) = 0 nm, Rth (550) = 232 nm, and a film C having a thickness of 158 μm was obtained.
The produced film A uses an adhesive and faces the polarizer of the polarizing plate A with a single-sided protective film so that the slow axis is orthogonal to the absorption axis of the polarizing element A with the single-sided protective film produced in (1). The polarizing plate 11 was manufactured by laminating on the side. In the polarizing plate 11, the film A is a retardation layer.
The produced film C uses an adhesive so that the MD (machine direction) coincides with the absorption axis of the polarizing element A with a single-sided protective film prepared in (1). The polarizing plate 12 was manufactured by laminating on the side facing the surface. In the polarizing plate 12, the film C is a retardation layer.
Further, an adhesive is used on the side of the polarizing element A with a single-sided protective film facing the polarizer so that the slow axis of the film A is orthogonal to the absorption axis of the polarizer A with a single-sided protective film produced in (1). Then, the film C was further bonded using the same pressure-sensitive adhesive to prepare a polarizing plate 13. In the polarizing plate 13, the film A and the film C are retardation layers, respectively.

(14) Preparation of VA Type Liquid Crystal Cell Having COA Structure A TFT (Thin Film Field Effect Transistor) element is manufactured on a glass substrate according to Example 20 of Japanese Patent Application Laid-Open No. 2009-141341, and further protected on the TFT element. A film was formed.
Subsequently, on the protective film, the compositions prepared as described in Examples 17, 18 and 19 of JP-A-2009-144126 are used as the colored photosensitive composition, respectively, and JP-A-2008-516262 is used. A color filter-on-array (COA) substrate was made according to the process described in Example 9a of. However, the concentration of the pigment in the colored photosensitive resin composition of each pixel is halved, and the coating amount is further adjusted so that the black pixel becomes 4.2 μm and the red element, the green element and the blue pixel become 3.5 μm. I did. Further, after forming a contact hole in the color filter, an ITO (Indium Tin Oxide) transparent pixel electrode electrically connected to the TFT element was formed on the color filter. Then, according to Example 1 of JP-A-2006-64921, a spacer was formed on the portion corresponding to the upper part of the partition wall (black matrix) on the ITO film.
Separately, a glass substrate on which an ITO transparent electrode is formed is prepared as a counter substrate, and the COA substrate and the transparent electrode of the counter substrate are each patterned for PVA (Patterned Vertical Alignment) mode, and further composed of vertical polyimide. An alignment film was provided.
After that, a sealant of an ultraviolet curable resin is applied by a dispenser method to a position corresponding to a black matrix outer frame provided around the RGB (Red Green Blue) pixel group of the color filter, and a liquid crystal display for PVA mode is dropped. Then, after bonding to the opposing substrate, the bonded substrate was irradiated with UV, and then heat-treated to cure the sealant. A liquid crystal cell was produced in this way.
Subsequently, the Δnd (590) of the produced liquid crystal cell was measured using AXOSCAN manufactured by AXOMETRICS and the attached software, and those having a Δnd (590) of 316 nm were selected, and the liquid crystal cells of Examples and Comparative Examples were selected. It was used as (VA type liquid crystal cell having a COA structure). Δnd (590) is the product of the thickness d (nm) of the liquid crystal layer of the liquid crystal cell and the refractive index anisotropy Δn at the wavelength of 590 nm of the liquid crystal layer.

(15) Preparation of backlight unit BL1 The backlight unit used in BenQ 55RW6600 was used as BL1. In the liquid crystal display device including BL1, the liquid crystal cell was installed with the COA substrate side facing the backlight unit side. The half width of the emission angle distribution in the vertical direction of BL1 was 25 °.

(16) Preparation of Backlight Unit BL2 A louver film PF12.1WS (3M) was installed on the backlight unit BL1 so as to cut the light in the vertical direction of the liquid crystal display device, and used as BL2. The half width of the emission angle distribution in the vertical direction of BL2 was 25 °.

(17) Preparation of Liquid Crystal Display Devices of Examples 1 to 12 and Comparative Examples 1 to 7 The liquid crystal display device of Example 1 was manufactured as follows.
The polarizing plate 1 is attached to the surface of the polarizing plate A with a single-sided protective film opposite to the protective film of the polarizing plate A to the surface of the liquid crystal cell on the opposite substrate side using an adhesive, and then the polarizing plate 3 is attached to the single-sided protective film. The surface of the polarizing plate A opposite to the protective film was attached to the surface of the liquid crystal cell on the COA substrate side using an adhesive. At this time, the absorption axis of the polarizing plate attached to the surface of the liquid crystal cell on the opposite substrate side and the absorption axis of the polarizing plate attached to the surface of the liquid crystal cell on the COA substrate side were arranged so as to be orthogonal to each other. Further, the liquid crystal cells to which the polarizing plates were attached were superposed so that the COA substrate side of the liquid crystal cells faced the backlight unit BL1 side, and the liquid crystal display device was completed. At the time of evaluation of this liquid crystal display device, the surface of the liquid crystal display device was installed so as to be perpendicular to the ground and the absorption axis of the polarizing plate attached to the opposite substrate side of the liquid crystal cell to be in the horizontal direction.
In the liquid crystal display devices of Examples 2 to 12 and Comparative Examples 1 to 7, the polarizing plates 1 to 17 and the polarizing plates 31 to 34 are attached to the liquid crystal cell using an adhesive in the configuration shown in Table 4 and backed up. It was completed in the same manner as the liquid crystal display device of Example 1 except that it was mounted on the light unit BL1 or BL2.

(18) Measurement of light leakage amount L ( φ, 60), L (0,60), L (180,60)
For each of the liquid crystal display devices of Examples and Comparative Examples, as a brightness value of white display measured at a predetermined polar angle from the normal direction of the liquid crystal panel in a dark room using a measuring device (BM5A, manufactured by TOPCON). , The amount of light leakage L ( φ, 60), L (0,60) and L (180,60) were measured, respectively. Regarding the light leakage amount L ( φ, 60), the light leakage amount was determined by changing the azimuth angle φ at intervals of 5 ° in the range of -30 to 30 ° and the range of 150 to 210 °. At the time of measurement, the distance between the measuring instrument and the liquid crystal panel was set to 700 mm.
Table 4 shows the maximum value of the measured light leakage amount L ( φ, 60) and the value of L (0,60) + L (180,60) for each of the liquid crystal display devices of the examples and the comparative examples. When the maximum value of the light leakage amount L ( φ, 60) is smaller than the value of L (0,60) + L (180,60), it means that Equation 1 is satisfied.

(19) Measurement of Haze of Polarizing Plate Each of the above polarizing plates was prepared by the same method as described above, and a polarizing plate sample (40 mm × 80 mm) was cut out from the prepared polarizing plate. The haze of the polarizing plate sample thus obtained was measured according to JIS K-6714 using a haze meter (HGM-2DP, Suga Test Instruments) in an environment of an atmospheric temperature of 25 ° C. and a relative humidity of 60%.

(20) Evaluation of VA type liquid crystal display device (20-1) Front contrast (CR)
For each of the liquid crystal display devices of Examples and Comparative Examples, the brightness value at the time of black display and the brightness value at the time of white display of the liquid crystal panel in the normal direction of the liquid crystal panel were measured in a dark room using a measuring device (BM5A, manufactured by TOPCON). , The front contrast (luminance value at white brightness / brightness value at black brightness) was calculated. At the time of measurement, the distance between the measuring instrument and the liquid crystal panel was set to 700 mm. Table 4 shows the front contrast ratio calculated as a relative ratio with the front contrast calculated for Comparative Example 3 as 100%. The following judgment was made based on the calculated front contrast ratio.
A (excellent): 110% <front contrast ratio B (good): 100% <front contrast ratio ≤ 110%
C (no improvement): Front contrast ratio ≤ 100%

(20-2) Evaluation of viewing azimuth It can be said that the wider the azimuth range with a small amount of light leakage centered on the left and right directions of the liquid crystal display device, the wider the left and right viewing azimuth. In order to index this, for each of the liquid crystal display devices of Examples and Comparative Examples, in a dark room, using a measuring instrument (BM5A, manufactured by TOPCON), the viewing azimuth in the right direction and the viewing direction in the left direction are carried out by the following procedure. The viewing azimuth angle was measured separately, and this average value was used as the viewing azimuth angle index.
First, in order to measure the viewing azimuth in the right direction, the brightness I (α) (α:) at the time of black display at 5 ° intervals from the azimuth of −45 ° to + 45 ° in the polar angle direction of 60 ° from the front of the liquid crystal display device. Azimuth) was measured.
Next, when the brightness value at an azimuth angle of 0 ° (viewing angle from the right) at a polar angle of 60 ° is I (0 °), the brightness value I (α) at each azimuth angle α is in the right direction. The azimuth angle range AR in which the ratio I (α) / I (0 °) to the brightness value I (0 °) in the field of view was 2.0 times or less was determined. For example, when I (α) / I (0 °) ≦ 2.0 from the azimuth angle −30 ° to 30 °, AR = 30− (-30) = 60 °.
Similarly, for the viewing azimuth in the left direction, the brightness I (α) at the time of black display is measured at 5 ° intervals from the azimuth of 135 ° to 225 ° in the polar angle direction of 60 ° from the front of the liquid crystal display device, and I ( The azimuth range AL in which α) / I (180 °) was 2.0 times or less was determined.
Next, the left-right viewing azimuth range index was calculated by the following formula.
Field azimuth index = (AR + AL) / 2
The following judgment was made based on the calculated values in the left-right viewing azimuth range.
A (excellent): 35 ° ≤ absolute value of left / right azimuth range index B (allowable): 30 ° ≤ absolute value of left / right azimuth range index <35 °
C (unacceptable): Absolute value of left / right azimuth range index <30 °

The above results are shown in Table 4 (Tables 4-1 and 4-2).

10 Liquid crystal layer 12 Color filter layer 14 Array member 16 Rear side substrate 18 Front side substrate 20 Rear side retardation layer 22 Front side retardation layer 24 Rear side polarizing element 26 Front side polarizing element 28 Backlight unit VA having LC COA structure Type liquid crystal cell PL1 Rear side polarizing plate PL2 Front side polarizing plate

Claims (6)

Includes LCD panel and backlight unit
When the front is the polar angle 0 °, the right direction is the azimuth angle 0 °, the left direction is the azimuth angle 180 °, L (x, y) is the azimuth angle x when black is displayed, and the light leakage amount is the polar angle y. The following formula 1:
Maximum value of L ( φ, 60) <L (0,60) + L (180,60)
Satisfied, where, L (phi, 60) azimuth phi, is the amount of light leakage when the polar angle 60 °, phi is in the range of scope and 150 to 210 ° of -30 to 30 ° ,
The liquid crystal panel
Front side polarizer,
Rear polarizer,
A VA type liquid crystal cell located between the front-side polarizing element and the rear-side polarizing element,
A front-side retardation layer located between the front-side polarizing element and the VA-type liquid crystal cell, and a rear-side retardation layer located between the rear-side polarizer and the VA-type liquid crystal cell.
Including
The VA type liquid crystal cell includes a liquid crystal layer and a color filter on array substrate on the rear side.
The thickness direction retardation Δnd (550) of the VA type liquid crystal cell measured at a wavelength of 550 nm is 280 nm or more and 350 nm or less, Δnd (550) is the product of Δn (550) and d, and Δn (550) is the above. The refractive index anisotropy of the liquid crystal layer at a wavelength of 550 nm, d is the thickness of the liquid crystal layer, and the unit of thickness is nm.
The absorption axis of the front-side polarizer and the absorption axis of the rear-side polarizer are orthogonal to each other.
The slow axis of the rear side retardation layer and the absorption axis of the rear side polarizer are orthogonal to each other.
The front-side retardation layer is a phase difference layer 1,
The in-plane retardation Re (550) measured at a wavelength of 550 nm of the retardation layer 1 is less than 20 nm.
The thickness direction retardation Rth (550) measured at a wavelength of 550 nm of the retardation layer 1 is 200 nm or more and 270 nm or less.
Before cut A-side retardation layer is a phase difference layer 2,
The in-plane retardation Re (550) measured at a wavelength of 550 nm of the retardation layer 2 is 130 nm or more and 155 nm or less.
The thickness direction retardation Rth (550) measured at a wavelength of 550 nm of the retardation layer 2 is 55 nm or more and 90 nm or less.
The in-plane retardation Re (450) measured at a wavelength of 450 nm, the in-plane retardation Re (550) measured at a wavelength of 550 nm, and the in-plane retardation Re (650) measured at a wavelength of 650 nm of the retardation layer 2 are
Re (450) ≤ Re (550) ≤ Re (650)
A VA type liquid crystal display device in which the retardation layer 1 and the retardation layer 2 include an optically anisotropic layer containing a polymerizable liquid crystal compound. The in-plane retardation Re (550) of the retardation layer 2 is 135 nm or more and 150 nm or less, and the thickness direction retardation Rth (550) of the retardation layer 2 is 57 nm or more and 87 nm or less. The liquid crystal display device described. The liquid crystal display device according to claim 1 or 2, wherein the optically anisotropic layer is a liquid crystal layer having a thickness of 5.0 μm or less. The liquid crystal display device according to claim 3, wherein the liquid crystal layer is a cured layer of a polymerizable composition containing a polymerizable liquid crystal compound. The liquid crystal display device according to any one of claims 1 to 4, wherein the half-value half width of the emission angle distribution in the vertical direction of the backlight unit is within 30 °. The liquid crystal display device according to any one of claims 1 to 5, further comprising a diffusion layer on the front surface of the liquid crystal panel.

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