JP2011085885A - Va liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a VA (Vertically Aligned) type liquid crystal display device with high frontal contrast. <P>SOLUTION: The VA type liquid crystal display device has: a front side polarizer (26); a rear side polarizer (24); a liquid crystal layer (10) disposed between the front side polarizer and the rear side polarizer; and one or two or more retardation layers disposed between the rear side polarizer (24) and the liquid crystal layer (10) (the whole of the one or two or more retardation layers disposed between the rear side polarizer and the liquid crystal layer is called as a "rear side retardation region"), wherein the rear side retardation region (20) as a whole satisfies 105 nm≤Rth(550), and a front side substrate (18) having a TFT array is disposed between the front side polarizer (26) and the liquid crystal layer (10), where Rth (λ) means a retardation (nm) in the thickness direction at a wavelength of λ nm. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  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.

  Incidentally, the front CR is determined by two transmittances (white luminance and black luminance) during white display and black display. One means for improving the transmittance of a liquid crystal display device during white display is a color filter on array (COA) structure (for example, Patent Documents 1 and 2). According to the COA structure, since the aperture ratio can be increased, the transmittance during white display can be increased. At present, there is a high interest in environmental problems, and adopting a COA structure to improve the transmittance contributes to the reduction of power consumption and is preferable from the viewpoint of the environment. In the non-COA structure, when the cell is formed by bonding the array substrate and the counter substrate having the color filter layer, it is necessary to align each color region constituting the color filter layer and the pixel electrode. If the structure is adopted, this alignment is not necessary. Therefore, the aperture ratio can be increased as compared with the conventional configuration, and as a result, the transmittance during white display can be improved. This COA substrate is usually used as a substrate (hereinafter sometimes referred to as “rear side substrate”) disposed on the light source side of the liquid crystal cell.

  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 3). In general, phase compensation films are arranged on the front and rear sides of the liquid crystal cell as the center, and the optical compensation is achieved by sharing the retardation required 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 the retardation film is 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 retardation is shared by the retardation film disposed on one side.

JP 2005-99499 A JP 2005-258004 A JP 2006-184640 A

As a result of intensive studies by the present inventor, the front contrast of the VA liquid crystal display device has a retardation film (retardation film) that contributes to reduction of light leakage occurring in an oblique direction during black display, that is, improvement of the viewing angle CR. ) Was found to be affected. In particular, in a VA liquid crystal display device in which a retardation film having a large retardation is arranged on the rear side, it has been found that the retardation of the retardation film causes a reduction in front CR. Conventionally, only the influence on the CR in the oblique direction has been studied for the retardation of the rear side retardation film. The influence of the retardation of the rear side retardation film on the front CR has been found by the study of the present inventors, and it can be said that it has never been known.
That is, an object of the present invention is to improve the front contrast of a VA liquid crystal display device having a retardation film having a large retardation on the rear side.
An object of the present invention is to further improve the front contrast of a VA liquid crystal display device in which the front CR is 1500 or more.

  As a result of various studies conducted by the present inventors in order to solve the above-mentioned problems, a TFT array substrate is used as a conventional rear substrate in a VA liquid crystal display device in which a retardation film having a large retardation is disposed on the rear side. In other words, it was found that the front CR of the VA-type liquid crystal display device could be remarkably improved when arranged as a front substrate. As a result of further investigation based on this knowledge, when the Rth of the entire retardation film arranged on the rear side is within a predetermined range, the front CR improvement effect by arranging the TFT array substrate as the front substrate is remarkable. As a result, the present invention has been completed.

That is, the means for solving the above problems are as follows.
[1] A front-side polarizer, a rear-side polarizer, a liquid crystal layer disposed between the front-side polarizer and the rear-side polarizer, and one layer disposed between the rear-side polarizer and the liquid crystal layer 2 or more retardation layers (one or two or more retardation layers arranged between the rear-side polarizer and the liquid crystal layer are referred to as “rear-side retardation regions”) The side phase difference area is the following formula (I)
(I): 105 nm ≦ Rth (550)
(However, Rth (λ) means retardation in the thickness direction (nm) at a wavelength of λnm);
And a front-side substrate having a TFT array is disposed between the front-side polarizer and the liquid crystal layer.
[2] The VA liquid crystal display device according to [1], further comprising a light shielding layer and / or an antireflection layer for suppressing reflection of the TFT array between the TFT array and the front polarizer.
[3] The VA liquid crystal display device of [1] or [2], wherein the front substrate is a color filter on array substrate.
[4] The rear side retardation region has the following formula (I ′):
(I ′): 105 nm ≦ Rth (550) ≦ 300 nm
The VA liquid crystal display device according to any one of [1] to [3], wherein:
[5] The rear side retardation region has the following formula (II):
(II): | Re (550) | ≦ 90 nm
Where Re (λ) means in-plane retardation (nm) at a wavelength λnm;
The VA liquid crystal display device according to any one of [1] to [4], wherein:
[6] One or two or more retardation layers disposed between the front polarizer and the liquid crystal layer as a whole (hereinafter, disposed between the front polarizer and the liquid crystal layer). The entire retardation layer of one layer or two or more layers is referred to as “front-side retardation region”), the following formula (III)
(III): | Rth (550) | ≦ 170 nm
The VA liquid crystal display device according to any one of [1] to [5], wherein:
[7] The front side retardation region is represented by the following formula (IV):
(IV): 30 nm ≦ Re (550) ≦ 90 nm
[6] The VA type liquid crystal display device according to [6].
[8] The VA liquid crystal display device according to any one of [1] to [5], wherein the front polarizer is directly bonded to the VA liquid crystal cell.

[9] Any of [1] to [8], wherein the rear-side retardation region is composed of one biaxial polymer film or includes one biaxial polymer film. VA type liquid crystal display device.
[10] Any one of [1] to [9], wherein the rear side retardation region is made of one uniaxial polymer film or includes one uniaxial polymer film. VA type liquid crystal display device.
[11] Any one of [1] to [10], wherein the front side retardation region and / or the rear side retardation region is made of a cellulose acylate film or includes a cellulose acylate film. VA type liquid crystal display device.
[12] Any of [1] to [11], wherein the front side retardation region and / or the rear side retardation region is made of a cyclic olefin polymer film or includes a cyclic olefin polymer film. VA type liquid crystal display device.
[13] The VA type of any one of [1] to [12], wherein the front side retardation region and / or the rear side retardation region is made of an acrylic polymer film or includes an acrylic polymer film. Liquid crystal display device.
[14] An acrylic system in which the front side retardation region and / or the rear side retardation region contains at least one unit selected from a lactone ring unit, a maleic anhydride unit, a glutaric anhydride unit, and a glutarimide unit. [13] The VA type liquid crystal display device according to [13], comprising an acrylic polymer film containing a polymer or containing the acrylic polymer film.
[15] The VA liquid crystal display according to any one of [1] to [14], wherein the front side retardation region and / or the rear side retardation region is made of polypropylene resin or contains polypropylene resin. apparatus.
[16] The VA liquid crystal display device according to any one of [1] to [15], 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, it is possible to provide a VA liquid crystal display device with high front contrast.

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 cross-sectional schematic diagram of an example of the conventional general VA type | mold liquid crystal display device used for reference. It is the schematic diagram used in order to demonstrate the effect | action of this invention. It is the schematic diagram used in order to demonstrate the effect | action of the conventional general VA type | mold liquid crystal cell used for reference.

Hereinafter, the present invention will be described in detail. In addition, the numerical range represented using “to” in this specification means a range including numerical values described before and after “to” as the lower limit value and the 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).
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 Re (λ), with the in-plane slow axis (determined by KOBRA 21ADH or WR) as the tilt axis (rotation axis) (if there is no slow axis, any in-plane film The light of wavelength λ nm is incident from each of the inclined directions in steps of 10 degrees from the normal direction to 50 degrees on one side with respect to the film normal direction (with the direction of the rotation axis as the rotation axis). KOBRA 21ADH or WR is calculated based on the measured retardation value, the assumed value of the average refractive index, and the input film thickness value.
In the above case, in the case of a film having a direction in which the retardation value is zero at a certain tilt angle with the in-plane slow axis from the normal direction as the rotation axis, retardation at a tilt angle larger than the tilt angle. The value is 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 absence of the 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.

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

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.

When the film to be measured cannot be expressed by a uniaxial or biaxial refractive index ellipsoid, that is, a film without a so-called optical axis, Rth (λ) is calculated by the following method.
Rth (λ) is from −50 degrees to +50 degrees with respect to the normal direction of the film, with Re (λ) being the in-plane slow axis (determined by KOBRA 21ADH or WR) and the tilt axis (rotating axis). In each of the 10 degree steps, light of wavelength λ nm is incident from the inclined direction 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, the assumed value of the average refractive index may be a value in a polymer handbook (John Wiley & Sons, Inc.) or a catalog of various optical films. 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).
KOBRA 21ADH or WR calculates nx, ny, and nz by inputting the assumed average refractive index and the film thickness. Nz = (nx−nz) / (nx−ny) is further calculated from the calculated nx, ny, and nz.

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. Further, the measurement wavelength of the refractive index is a value at λ = 550 nm in the visible light region unless otherwise specified.
Further, in this specification, numerical values, numerical ranges, and qualitative expressions (for example, “equivalent”, “equal”, etc.) indicating optical characteristics of each member such as a retardation region, a retardation film, and a liquid crystal layer are used. ) 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. (The size of retardation does not matter.) The retardation film is synonymous with the retardation film and retardation layer. 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. The viewing angle contrast (CR) is an oblique direction inclined from the normal direction of the display surface (for example, a direction defined by an azimuth angle direction of 45 degrees and a polar angle direction of 60 degrees with respect to the display surface). ) Means the contrast calculated from the white luminance and the black luminance measured.

The present invention relates to a VA liquid crystal display device having a TFT array substrate as a front side substrate. FIG. 1 is a schematic sectional view of an example of the liquid crystal display device of the present invention, and FIG. 2 is a schematic sectional view of a conventional general VA liquid crystal display device for reference.
The VA side liquid crystal display device of the present invention shown in FIG. 1 has a front side polarizer 26, a rear side polarizer 24, and a liquid crystal layer 10 disposed between the front side polarizer 26 and the rear side polarizer 24. Further, between the rear polarizer 24 and the liquid crystal layer 10, there is a rear side retardation region 20 composed of one or more retardation layers, and between the front polarizer 26 and the liquid crystal layer 10. Has a front side retardation region 22 composed of one or more retardation layers. In the liquid crystal cell LC of the VA liquid crystal display device shown in FIG. 1, the liquid crystal layer 10 is sandwiched between the front side substrate 18 and the rear side substrate 16, and the array member 14 and the color filter layer 12 are connected to the front side substrate 18 and the liquid crystal. The liquid crystal cell is disposed between the layer 10 and the liquid crystal cell.

  FIG. 2 is a schematic cross-sectional view of an example of a conventional general VA liquid crystal display device having a non-COA liquid crystal cell LC ′ as a reference example. In FIG. 2, the liquid crystal cell LC ′ includes a liquid crystal layer 50, a front side substrate 58 and a rear side substrate 56 that sandwich the liquid crystal layer 50, and a color filter layer 52 that is different from the array member 54. 58, a liquid crystal cell having a non-COA structure.

In general, in the VA liquid crystal display device, the liquid crystal layer is in a vertical alignment 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. 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.
In addition to the fluctuation of the liquid crystal molecules in the liquid crystal layer, the present inventor also includes the retardation of the retardation film disposed between the rear polarizer and the liquid crystal layer. I found that there was a cause.

Normally, light having directivity is incident on the rear polarizer from the backlight unit of the VA liquid crystal display device, but the light incident from an oblique direction is the rear where a rear retardation film or the like is disposed. Ellipsoidal polarization is achieved by the retardation of the side retardation region (hereinafter referred to as “Ret rear”). After that, the elliptically polarized light is incident on the liquid crystal cell, and the present inventors diligently studied to find that the elliptically polarized light is converted into each member (liquid crystal, color filter, black matrix) in the liquid crystal cell. When the light is incident on the array substrate structure, the protrusion structure of the counter substrate, the slit on the common electrode on the counter substrate, etc., the light is scattered in the front due to optical phenomena such as scattering and diffraction in each member. Was found to be reduced. That is, the present inventor has found that the amount of reduction in the front CR is determined by the relationship between the Ret rear and the optical phenomenon of each member of the liquid crystal cell. Based on this knowledge, further investigation was made and a TFT array (preferably further a color filter layer thereon) was arranged between the front substrate and the liquid crystal layer, and the rear through which the light passed before entering the liquid crystal cell. The side phase difference region (20 in FIG. 1) is represented by the following formula (I)
(I): 105 nm ≦ Rth (550)
It has been found that the front CR is remarkably improved by satisfying. As long as the phase difference of the entire retardation region that passes through before the light enters the liquid crystal cell satisfies the above formula (I), the light incident from the oblique direction is then subjected to the array member and the color filter layer in the liquid crystal cell. The light leakage in the front direction during black display is excessively increased even if the light is diffused or diffracted by the light and becomes light traveling in the normal direction or affected by the fluctuation of the liquid crystal molecules in the liquid crystal layer. As compared with a VA type liquid crystal display device having a general configuration in which liquid crystal cells having a non-COA structure are arranged, the front CR can be remarkably improved.
If the COA substrate is arranged as the rear substrate as in the conventional case in the VA liquid crystal display device in which the Rth of the rear side retardation region is within the range of the present invention, the front CR is rather lowered, and the effect of the present invention. Cannot be obtained. That is, the effect of the present invention is completely different from the effect accompanying the increase in the aperture ratio due to the adoption of the COA structure in principle.

  The reason why the front CR is improved in the VA liquid crystal display device of the present invention shown in FIG. 1 compared to the conventional VA liquid crystal display device shown in FIG. 2 is summarized as shown in FIGS. It is done. FIGS. 3 and 4 show liquid crystal cells LC and LC ′ when the phase difference in the rear phase difference region (20 or 60) of the liquid crystal display device shown in FIGS. The tendency of the influence which each member arrange | positions on a front CR direction, and the strength of the influence are put together. In FIG. 3B and FIG. 4B, “↑” indicates the action of increasing the front CR, and “↓” indicates the action of lowering 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. In FIGS. 3 and 4, for the sake of simplification of description, description will be made by paying attention to three of a CF member (color filter and black matrix), a liquid crystal layer, and an array member (TFT array).

The liquid crystal display device of the present invention is characterized in that a front side substrate having a TFT array is disposed between a front side polarizer and a liquid crystal layer. When a color filter is provided, the color filter is also disposed on the front substrate.
The dependency of incident light on the incident polarization state of light leakage during black display due to optical phenomena in the color filter, black matrix, and TFT array all show the same tendency, but the contribution of the black matrix is relatively small. The position of the black matrix in the liquid crystal display device may be anywhere in the liquid crystal cell, but is preferably located between the front polarizer and the liquid crystal layer.

  As summarized in FIG. 4B, in the VA type liquid crystal display measure of the conventional general structure, since the relationship between the CF member and the array member, and the Ret rear, which have a large influence on the front CR, is opposite to each other, That is, when the Ret rear becomes larger, the optical phenomenon due to the CF member acts in the direction of increasing the front CR, while the optical phenomenon due to the array member acts in the direction of lowering the front CR, so the mutual action is offset. Furthermore, the front CR is unavoidable due to the strong effect of the optical phenomenon of the array members.

  On the other hand, in the liquid crystal cell of FIG. 3A which is an example of the present invention, as summarized in FIG. 3B, the relationship between the CF member and the array member, which has a great influence on the front CR, and the Ret rear are equal to each other. That is, when the Ret rear becomes large, the optical phenomenon due to the CF member and the array member both acts in the direction of increasing the front CR, so when the Ret rear becomes large, the optical phenomenon of both the CF member and the array member causes CR is improved. Further, since the Ret rear becomes large, the scattering phenomenon in the liquid crystal layer also acts in the direction of increasing the front CR. As a result, compared with the VA type liquid crystal cell LC ′ having the normal structure shown in FIG. 4A, the front CR is remarkably improved in the liquid crystal display device employing the VA type liquid crystal cell LC according to the present invention. .

The reason why the optical phenomenon of each member in the liquid crystal cell reverses the tendency of the influence on the front CR depending on the arrangement is as follows.
First, in the “liquid crystal fluctuation scattering” that occurs in the liquid crystal layer, the larger the ellipticity of the incident polarized light just before being scattered, the less light leakage during black display, and as a result, the front CR becomes higher. The larger the Ret rear, the greater the ellipticity of the polarized light incident on the liquid crystal layer. Therefore, from the viewpoint of fluctuation scattering of the liquid crystal layer, the larger the Ret rear, the higher the front CR.
On the other hand, the optical phenomenon that occurs in the array member and the CF member shows a tendency opposite to that of “liquid crystal fluctuation scattering”. Light leakage, and as a result, the front CR becomes higher. In the member in which light is incident before entering the liquid crystal layer, for example, the array member 54 in FIG. 4A, the ellipticity of the polarized light incident on the array member 54 increases as the Ret rear increases. The optical phenomenon caused by 54 acts in the direction of lowering the front CR. However, in a member in which light enters after passing through the liquid crystal layer, not only Ret rear but also Δnd of liquid crystal affects the ellipticity of incident polarized light. In the VA type, Δnd of the liquid crystal layer is about 280 to 350 nm. As a result, the larger the Ret rear, the smaller the ellipticity of the polarized light incident on the member after passing through the liquid crystal layer. Therefore, in the member in which light enters after entering the liquid crystal layer, for example, the color filter 12 and the array member 14 in FIG. 3A and the color filter 52 in FIG. Since the ellipticity of polarized light incident on these members increases, any optical phenomenon caused by these members acts in the direction of increasing the front CR.

  In the VA type liquid crystal cell LC ′ having the conventional general configuration shown in FIG. 4A, even if the Ret rear is enlarged, the action caused by the optical phenomenon of the color filter 52 is canceled by the action caused by the optical phenomenon of the array member 54. Therefore, the front CR cannot be improved. On the other hand, in the VA liquid crystal cell LC of FIG. 3A according to the present invention, when the Ret rear is increased, the optical phenomena of the color filter 12 and the array member 14 both act to improve the front CR. Compared with the conventional VA liquid crystal display device, the front CR can be remarkably improved.

  The influence of the Ret rear 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. 1, it is preferable that the optical characteristics of the front side retardation region of the front side 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 (Δn is the birefringence of the liquid crystal layer and d is the thickness of the liquid crystal layer) 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 of the front side retardation region, particularly Rth, varies depending on the value of Δnd of the liquid crystal layer. For the purpose of improving the diagonal contrast, preferable (front side and rear side) phase difference region combinations for Δnd are described in various publications, for example, described in Patents 3282986, 3666666, and 3556159. Yes, you can refer to it.
A preferable range of the optical characteristics of the front side retardation region will be described later.

In the present invention, the rear side retardation region (20 in FIG. 1) may have a single layer structure or a laminate composed of two or more layers. In an embodiment having a single layer structure, the layer needs to satisfy the formula (I), and in an embodiment of a laminate of two or more layers, the laminate needs to satisfy the formula (I) as a whole.
In the present invention, the rear side phase difference region (20 in FIG. 1) is represented by the following formula (I ′):
(I ′): 105 nm ≦ Rth (550) ≦ 300 nm
Preferably satisfying the following formula (I ")
(I "): 150 nm ≦ Rth (550) ≦ 300 nm
Is more preferable, and the following formula (I ′ ″)
(I ′ ″): 200 nm ≦ Rth (550) ≦ 300 nm
Is more preferable. When Rth (550) is 300 nm or less, industrial production by a solution casting method (solution casting method) or a melt extrusion method widely used in film production becomes possible, which is preferable.

Further, in the present invention, the rear side retardation region has the following formula (II):
(II): | Re (550) | ≦ 90 nm
It is preferable to satisfy the following formula (II ′)
(II ′): 20 nm ≦ Re (550) ≦ 80 nm
Preferably satisfies the following formula (II ")
(II "): 30 nm ≦ Re (550) ≦ 75 nm
It is more preferable to satisfy It is preferable that Re (550) is in the above range because optical compensation can be performed by disposing one retardation film having excellent industrial productivity in the front side retardation region and the rear side retardation region, respectively. .

In the present invention, the front side CR is improved by the rear side phase difference region satisfying the above formula (I), but the viewing angle CR is further adjusted by adjusting the optical characteristics of the front side phase difference region. Can be improved. From the viewpoint of improving the viewing angle CR, the front side retardation region is expressed by the following formula (III)
(III): | Rth (550) | ≦ 170 nm
Preferably satisfies the following formula (III ′):
(III ′): | Rth (550) | ≦ 140 nm
More preferably, the following formula (III ")
(III "): | Rth (550) | ≦ 100 nm
Is more preferable.
Further, the front side phase difference region is represented by the following formula (IV):
(IV): 30 nm ≦ Re (550) ≦ 90 nm
Preferably satisfying the following formula (IV ′)
(IV ′): 35 nm ≦ Re (550) ≦ 80 nm
It is more preferable to satisfy the following formula (IV ")
(IV "): 40 nm ≦ Re (550) ≦ 75 nm
Is more preferable.

Δnd (550) of the VA liquid crystal cell (d is the thickness (nm) of the liquid crystal layer, Δn (λ) is the refractive index anisotropy at the wavelength λ of the liquid crystal layer, and Δnd (λ) is Δn (λ) Is generally about 280 to 350 nm. In this case, the rear side retardation region arranged on the rear side is:
180 nm ≦ Rth (550) ≦ 300 nm
It is preferable that
200 nm ≦ Rth (550) ≦ 280 nm
It is more preferable that
On the other hand, considering the production suitability of the retardation film, a configuration using a retardation film with Rth (550) ≦ 230 nm may be practically preferable. 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 development of retardation. However, when the draw ratio is increased, 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 film having good production suitability, the rear side retardation region is 180 nm ≦ Rth (550) ≦ 230 nm.
It is preferable that
200 nm ≦ Rth (550) ≦ 230 nm
It is more preferable that Furthermore, from the viewpoint of viewing angle compensation, the front side phase difference region is
0 nm ≦ Rth (550) ≦ 90 nm
It is preferable that
20 nm ≦ Rth (550) ≦ 70 nm
It is more preferable that

  As described above, Δnd (550) of the VA type liquid crystal cell is generally about 280 to 350 nm, in order to increase the transmittance during white display as much as possible (= to increase the front CR). On the other hand, when Δnd (550) is 280 nm or less, white luminance slightly decreases with a decrease in Δnd (550), but since the cell thickness d decreases, the liquid crystal display device is excellent in high-speed response. The feature of the present invention that a high front CR is obtained as a result of less light leakage in the front direction if the rear retardation region is low retardation is effective in any liquid crystal display device of Δnd (550). There is.

  A liquid crystal display device is required to have high-speed response performance as well as front CR performance. In order to achieve high-speed response, the thickness d of the cell may be reduced. However, when Δnd (550) is 280 nm or less, the white luminance decreases as Δnd (550) decreases, and therefore the front CR also decreases. However, it is possible to suppress light leakage in the cell by using a retardation film having good Rth (550) ≦ 230 nm in the rear side retardation region, and without arranging the front side retardation region, Since viewing angle compensation is possible, an inexpensive liquid crystal display can be manufactured.

  In the present invention, a TFT array is formed on the front substrate. The TFT array is a member including a drive circuit, wiring, and the like, and is a member having a high reflectance. Therefore, when the TFT array is formed on the front side, that is, the display surface side substrate, the visibility due to internal reflection by the TFT array, particularly the visibility in a bright room, may be a problem. In order to maintain good visibility not only in the dark room but also in the bright room, for example, an antireflection layer and / or a light shielding layer for suppressing reflection of the TFT array between the front-side polarizer and the TFT array, Alternatively, it is preferable to form a layer having both antireflection and light shielding functions. For example, the antireflection layer and / or the light shielding layer is disposed between the front substrate surface and the TFT array, or between the front substrate surface and the front polarizer. Various proposals have been made for an antireflection film, a light shielding film, and a film having both functions, and any of them can be used. For example, an embodiment in which a multilayer including a layer of chromium or a chromium compound is laminated (described in JP-A-8-179301 and JP-A-8-234664), and an embodiment in which a black resin is used as a light-shielding agent (JP-A-11). No. 349898) can be used. One example is an example in which a black layer patterned in the same manner as the TFT array is formed between the TFT array and the substrate.

A preferred embodiment of the present invention is an embodiment in which the front side substrate (18 in FIG. 1) of the liquid crystal cell (LC in FIG. 1) has a color filter layer together with the TFT array. More specifically, a color filter on array (COA) substrate is used as the front substrate. The COA substrate is a substrate having a structure in which a color filter is formed on an active matrix substrate having a TFT array. Initially, the COA substrate was only for forming a color filter on a normal TFT substrate, but recently, in order to improve display characteristics, a pixel electrode is formed on the upper side of the color filter, and a small hole called a contact hole is formed. In general, a structure in which the pixel electrode and the TFT are connected to each other is provided. A COA substrate having any structure may be used as the front side substrate of the present invention. In the COA substrate, the color filter layer is thicker than the conventional color filter layer (about 1 to 2 μm), and generally about 1 to 4 μm. This is to suppress parasitic capacitance generated between the end of the pixel electrode and the wiring. The color filter layer of the liquid crystal display device of the present invention preferably has a thickness of about 1 to 4 μm, but is not limited to this range. Further, when manufacturing a liquid crystal cell using a COA substrate, it is necessary to pattern the pixel electrode on the color filter layer, and resistance to an etching solution or a stripping solution is required. For this purpose, a color filter material (colored photosensitive composition) whose film thickness is adjusted to be thick is used, but a two-layer structure of color filter layer + overcoat layer formed of a normal color filter material may be used. In the present invention, any structure of the COA substrate may be used as the front substrate.
The COA substrate is described in JP-A-2007-240544 and JP-A-2004-163979 in addition to the above-mentioned Patent Documents 1 and 2, and in the present invention, any COA substrate of any configuration is used. It can be employed as a front side substrate.

  Further, the color filter of the liquid crystal display device of the present invention has a plurality of different colors (for example, three primary colors of red, green, and blue light, transparent, Yellow, cyan, etc.). 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, the spin coater method is employed in the initial stage, and the slit & spin type coater method is employed from the viewpoint of liquid saving. 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 due to 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 and finer pigments by the build-up method have been increased. Used for contrast. Any coloring material may be used in the present invention.

  In the present invention, all or part of the rear side phase difference region (20 in FIG. 1) and the front side phase difference region (22 in FIG. 1) are respectively composed of the rear side polarizer (24 in FIG. 1) and the front side. It may also function as a protective film for the polarizer (26 in FIG. 1). Although omitted in FIG. 1, the rear polarizer has a functional film such as a protective film, an antifouling film, an anti-reflection film, an anti-glare film, or an anti-static film on the surface of the backlight side. Similarly, the front-side polarizer has a functional film such as a protective film, an antifouling film, an anti-reflection film, an anti-glare film, and an anti-static film on the display surface side surface. May be.

  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 Japanese Patent Application Laid-Open No. 2006-215326 and Japanese Patent Publication No. 2008-538819. A high front contrast can be obtained with a photo-alignment type or PSA. The effect shown in the present invention is further enhanced by applying it to a panel exhibiting high contrast.

  The effect of improving the front contrast shown in the present invention is further enhanced 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 typical example is a brightness enhancement film (BEF), which is a registered trademark of 3M USA. 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" towards the viewer To do. Patent documents that disclose that a luminance control member having a repetitive array structure of prisms represented by BEF is adopted for a display include Japanese Patent Publication No. 1-37801, Japanese Patent Laid-Open No. 6-102506, Many examples are known as exemplified in Japanese Patent Laid-Open No. 10-506500.

  In addition, it is desirable to use a lens array sheet in order to improve the light collecting property. The lens array sheet includes a lens surface in which a plurality of unit lenses formed in a convex shape at a predetermined pitch are two-dimensionally arranged, and a lens array sheet having a flat surface opposite to the lens surface, the flat surface The lens array sheet is characterized in that a light reflecting layer that reflects light rays is formed on a non-light-condensing surface area of the lens. Also, a lens array sheet in which a plurality of convex cylindrical lenses formed at a predetermined pitch are arranged in parallel and a lens array sheet having a flat surface opposite to the lens surface, the flat surface includes: There is a lens array sheet characterized in that a light reflecting layer for reflecting a striped light beam in a longitudinal direction is formed on a non-light-condensing surface region of the convex cylindrical lens. As the lens array sheet, 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 shape having a bottom shape such as a circle, a rectangle, and a hexagon. Examples thereof include a lens array sheet in which unit lenses composed of curved surfaces are two-dimensionally arranged in a plane. Patent documents describing these include JP-A-10-241434, JP-A-2001-201611, JP-A-2007-256575, JP-A-2006-106197, JP-A-2006-208930, JP-A-2007-. Japanese Patent No. 213035 and Japanese Patent Application Laid-Open No. 2007-41172 are known.

  The present invention is effective even for a display having a wide color reproduction range 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 wavelengths are R (red) 610 nm or more, G (green) 530 nm, and B (blue) 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, there is description in JP-A-2004-78102. The red color filter preferably has a low transmittance at the peak positions of the green LED and the blue LED, the green color filter preferably has a low transmittance at the peak position of the blue LED and the red LED, and the blue color filter has a red LED and a green color. It is desirable that the transmittance at the peak position of the LED is small. Specifically, all of these transmittances are desirably 0.1 or less, more preferably 0.03 or less, and further 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.

  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 JP2009-14892A.

  In addition, the VA liquid crystal display device of the present invention may be configured to perform display by a field sequential driving method. In the field sequential driving method, the color filter layer may not be provided. The field sequential driving method 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.

Hereinafter, various members used in the VA liquid crystal display device of the present invention will be described in detail.
1. Rear-side retardation region and front-side retardation region In the present invention, the entire retardation layer of one layer or two or more layers disposed between the rear-side polarizer and the VA liquid crystal cell is referred to as “rear-side retardation”. This is called “region”. The rear side phase difference region as a whole satisfies the above formula (I). It is preferable that the above formula (II) is further satisfied.
In the present invention, from the viewpoint of the viewing angle CR, the entire retardation layer of one layer or two or more layers disposed between the front-side polarizer and the VA-type liquid crystal cell, that is, the front-side retardation region, There may be a phase difference that contributes to the improvement of the viewing angle CR in relation to the phase difference of the rear side phase difference region. In the embodiment having the front side phase difference region, specifically, the front side phase difference region preferably satisfies the above formulas (III) and (IV).
There are no particular restrictions on the material of each layer constituting the rear side retardation region and the front side retardation region. The retardation region satisfying the formulas (I) and (II) or the retardation region satisfying the formulas (III) and (IV) can be constituted by one or more biaxial films. It can also be configured by combining two or more uniaxial films, such as a combination of a C plate and an A plate. Of course, it can also be configured by combining one or more biaxial films and one or more uniaxial films.

  There are no particular restrictions on the materials constituting the rear side and front side phase difference regions. 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 more polymers are selected from the above, and a polymer film is produced using the polymer as a main component, and in a combination that satisfies the above characteristics, the rear side and front side retardation regions It can be used in manufacturing.

  It is preferable that the chromatic dispersion of the in-plane retardation Re in the rear side and front side retardation regions 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 (630) is satisfied. The reason is that if the Re in the rear side and the front side phase difference regions are reverse wavelength dispersive, the optical wavelength is optimized at the center wavelength of about 550 nm, and the entire visible light is optimized. This is because there is a tendency.

As a retardation film satisfying the above formulas (I) and (II), or a retardation film satisfying the above formulas (III) and (IV) as a single layer or as a plurality of whole layers, a cellulose acylate film, Acrylic polymer films, cyclic olefin polymer films, and polypropylene polymer films are preferred.
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 with a hydroxyl group of cellulose is not particularly limited, but the degree of binding of acetic acid and / or a fatty acid having 3 to 22 carbon atoms to be substituted with a hydroxyl group of cellulose is measured, The degree of substitution can be obtained by calculation. As a measuring method, it can carry out according to ASTM D-817-91.

As a raw material of the cellulose acylate film, cellulose acetate having an acetyl substitution degree of 2.00 to 3.00 is preferable. The film is prepared to have a desired retardation by stretching. From the viewpoint of the expression of retardation during stretching, a lower acetyl substitution degree is preferable. However, the lower the acetyl substitution degree, the higher the Rth of the unstretched film. Therefore, the retardation film of the VA liquid crystal display device preferably has a acetyl substitution degree of 2.00 to 2.65. More preferably, it is .20 to 2.65, and further preferably 2.30 to 2.60.
On the other hand, in order for the retardation film to exhibit reverse wavelength dispersion, it is preferable that the degree of acetyl substitution is higher, specifically 2.65 to 3.00, and preferably 2.75 to 3.00. More preferably, it is more preferably 2.80 to 3.00.
In addition, the cellulose acylate 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. Furthermore, 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 75000 to 230,000, and more preferably 78000 to 120,000. Further preferred.

  The cellulose acylate film 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.

In producing the cellulose acylate film for the rear side and front side retardation regions, it is preferable to use a retardation developer 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-shaped compound is preferably 0.1 to 30 parts by mass, and 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 a range of 0.05 to 20 parts by mass, and in a range of 0.1 to 15 parts by mass, with respect to 100 parts by mass 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 developer 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 hetero ring 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 preparing the cellulose acylate film for the rear side and front side retardation regions 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-shaped compound that can be used in the present invention include compounds described in JP-A-2007-268898, [0053] to [0095].

(3) Positive birefringent compound A positive birefringent compound is a compound in which light is incident on a layer formed by uniaxial orientation of molecules, and the refractive index of light in the orientation direction is the orientation direction. A polymer that is larger than the refractive index of light in a 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 kind of 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 aforementioned 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-propanediol, 1,3-propanediol, and 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. 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.

  Preferred examples of the alkyl ether diol having 4 to 20 carbon atoms include polytetramethylene ether glycol, polyethylene ether glycol and 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. As examples of these, commercially useful polyether glycols typically 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. 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 a carboxylic acid or an OH group.
In this case, the monoalcohol is preferably a substituted or unsubstituted monoalcohol having 1 to 30 carbon atoms, 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 alcohol such as dodecaoctanol, allyl alcohol, oleyl alcohol, benzyl alcohol, 3-phenyl Examples thereof 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.

  Moreover, when sealing with a monocarboxylic acid residue, the monocarboxylic acid used as a 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). In addition, Japanese Patent Laid-Open Nos. 05-155809, 05-155810, Japanese Patent Laid-Open Nos. 05-97073, 2006-259494, 07-330670, 2006-342227, 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, 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 especially preferable that it is -20 mass parts.

  In the present invention, the cellulose acylate solution 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.

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

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.

The acrylic polymer film is formed of a resin composition containing a (meth) acrylic resin as a main component. A (meth) acrylic resin film is preferred because the photoelastic coefficient tends to be negative. The (meth) acrylic resin is not particularly limited. For example, polyacrylic acid ester, polymethacrylic acid ester, methyl methacrylate-acrylic acid copolymer, methyl methacrylate-methacrylic acid copolymer, methyl methacrylate- Acrylic acid ester copolymer, methyl methacrylate-methacrylic acid ester copolymer, methyl methacrylate-acrylic acid ester-acrylic acid copolymer, methyl methacrylate-acrylic acid ester-methacrylic acid copolymer, methyl acrylate- Styrene copolymer, methyl methacrylate-styrene copolymer (MS resin), polymer having alicyclic hydrocarbon group (for example, methyl methacrylate-cyclohexyl methacrylate copolymer, methyl methacrylate-acrylic acid) Norbornyl copolymer, methyl methacrylate-metac Le acid norbornyl copolymer) and the like. Of these, polyacrylic acid C ₁ ~ ₆ alkyl, polymethacrylic acid C ₁ ~ ₆ alkyl are preferred, methyl methacrylate-based resins are particularly preferred. The methyl methacrylate resin preferably contains methyl methacrylate in a range of 50 to 100% by weight of the whole, more preferably in a range of 70 to 100% by weight of the whole. The (meth) acrylic resin is described in detail in Japanese Patent Application Laid-Open No. 2008-231234 and Japanese Patent Application Laid-Open No. 2008-9378 as an example, and can be referred to.

  Specific examples of the (meth) acrylic resin include, for example, a trade name “Acrypet VH” manufactured by Mitsubishi Rayon Co., Ltd., a product name “Acrypet VRL20A” manufactured by the same company, and Japanese Patent Application Laid-Open No. 2004-70296. Examples thereof include acrylic resins and methacrylic resins having a ring structure in the molecule, high-Tg acrylic resins and methacrylic resins obtained by intramolecular crosslinking or intramolecular cyclization reactions.

  As the (meth) acrylic resin, it is preferable to use a (meth) acrylic resin having any of a lactone ring structural unit, a maleic anhydride unit, a glutaric anhydride unit, or a glutarimide unit. Since these resins have a ring structure in the molecule, they are excellent in heat resistance, transparency and mechanical strength.

  The (meth) acrylic resin having a lactone ring structure preferably has a ring structure represented by the following general formula (15).

In the formula, R ¹ , R ² and R ³ each independently represent a hydrogen atom or an organic residue having 1 to 20 carbon atoms. The organic residue may contain an oxygen atom.

  Examples of the (meth) acrylic resin having a lactone ring structure include JP 2000-230016, JP 2001-151814, JP 2002-120326, JP 2002-254544, and JP 2005. No. 146084, JP-A-2006-171464, and the like.

  Examples of the maleic anhydride structure include maleic anhydride units represented by the following general formula (16).

In the general formula (16), R ³¹ and R ³² each independently represent a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms. In the case where the alkyl group having 1 to 5 carbon atoms has a substituent, examples of the substituent include halogen, —OH, —COOH, —NH ₂ , —SO ₃ H and the like.

  As the (meth) acrylic resin having a maleic anhydride unit, for example, those described in JP2008-158165A, JP2009-109695A, and the like can be used.

  Examples of the glutaric anhydride structure include a glutaric anhydride unit represented by the following general formula (17).

However, in said general formula (17), R < ¹¹ > and R < ¹² > represent a hydrogen atom or a substituted or unsubstituted C1-C5 alkyl group each independently. In the case where the alkyl group having 1 to 5 carbon atoms has a substituent, examples of the substituent include halogen, —OH, —COOH, —NH ₂ , —SO ₃ H and the like.

  Examples of the (meth) acrylic resin having a glutaric anhydride unit include, for example, JP-A-2004-70290, JP-A-2004-70296, JP-A-2004-163924, and JP-A-2004-292812. JP, 2005-314534, JP, 2006-206881, JP, 2006-265532, JP, 2006-283013, JP, 2006-299005, JP, 2006-335902, etc. What is described can be used.

  The (meth) acrylic resin having a glutarimide structure has a ring structure represented by the following general formula (18).

In the general formula (18), R ²¹ and R ²² each independently represent a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 8 carbon atoms. R ²³ represents a substituted or unsubstituted alkyl group having 1 to 18 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 12 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 10 carbon atoms. When the alkyl group having 1 to 8 carbon atoms has a substituent, examples of the substituent include halogen, —OH, —COOH, —NH ₂ , —SO ₃ H and the like. When the alkyl group having 1 to 18 carbon atoms, the cycloalkyl group having 3 to 12 carbon atoms, and the aryl group having 6 to 10 carbon atoms have a substituent, examples of the substituent include halogen, -OH , —COOH, —NH ₂ , —SO ₃ H and the like. Preferably, R ²¹ and R ²² are each independently a hydrogen atom or a methyl group, and R ²³ is a hydrogen atom, a methyl group, or a cyclohexyl group. More preferably, R ¹ is a methyl group and R ²² is a hydrogen atom. The repeating unit represented by the general formula (18) (hereinafter sometimes referred to as “first unit”) may be a single type, and includes a plurality of types in which R ²¹ , R ²² and R ²³ are different. It does not matter.

  Examples of the (meth) acrylic resin having a glutarimide structure include JP-A-2006-309033, JP-A-2006-317560, JP-A-2006-328329, JP-A-2006-328334, and JP-A-2006. No. 3,374,491, JP-A 2006-337492, JP-A 2006-337493, JP-A 2006-337569, and the like can be used.

  The (meth) acrylic resin having a glutarimide structure of the present invention may be obtained by imidizing a resin having a unit capable of imidization such as methacrylic acid methyl ester with ammonia or a substituted amine. Good. Examples of such resins include glutarimide resins described in U.S. Pat. No. 3,284,425, U.S. Pat. No. 4,246,374, and JP-A-2-153904.

  The (meth) acrylic resin having a lactone ring structural unit, a glutaric anhydride unit, or a glutarimide unit is other than the ring structure represented by the general formula (15), (16), (17), or (18). You may have a structure. The structure other than the ring structure represented by the general formula (15), (16), (17), or (18) is not particularly limited, but (meth) acrylic acid ester, hydroxyl group-containing monomer, unsaturated A polymer structural unit (repeating structural unit) formed by polymerizing at least one selected from carboxylic acid and a monomer represented by the following general formula (19) is preferable.

In the formula, R ⁴ represents a hydrogen atom or a methyl group, X represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group, an —OAc group, a —CN group, — or a CO—R ⁵ group, and Ac The group represents an acetyl group, and R ⁵ represents a hydrogen atom or an organic residue having 1 to 20 carbon atoms.

  In addition, when a cellulose polymer is added to the acrylic polymer film as a polymer other than the acrylic polymer, the physical properties of the acrylic and the cellulose act in a complementary manner, resulting in a material having desired characteristics. preferable. The addition amount of the cellulose polymer is preferably about 5 to 40% by mass (ratio to the whole polymer). For example, an acrylic polymer film has low moisture permeability, so that residual moisture after polarizing plate processing is difficult to escape, but by adding a cellulose polymer, appropriate moisture permeability can be given. As a specific example, a film to which 10% by mass of cellulose acylate (CTA described in Table 3) is added and a film to which 30% by mass of cellulose acylate propionate (CAP482-20 (manufactured by Eastman Chemical Co.)) are added Is mentioned.

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. You can refer to it. Examples of the cyclic olefin-based polymer film that can be used as a retardation film constituting the rear-side and front-side retardation regions include norbornene-based polymer films, and commercially available polymers include Arton (manufactured by JSR), Zeonore (Japan) Zeon) or the like can be used.

Polypropylene polymer film:
The polypropylene polymer film is a film made of or containing a polypropylene resin, and preferably contains one or more of the polypropylene resins as a main component. If necessary, an additive described later may be contained. The polypropylene resin can be selected from propylene homopolymers. Moreover, it can select from the copolymer obtained by copolymerizing the monomer copolymerizable with propylene with propylene. However, it is preferable that propylene is the main monomer, and the amount of the comonomer to be copolymerized is smaller than that of propylene, for example, 20% by mass or less, preferably 10% by mass or less. The lower limit is not particularly limited (of course, it may be 0% by mass), but in order for the characteristics to be affected by the copolymerization of the comonomer, 1% by mass or more of comonomer will be necessary.

Examples of comonomers copolymerized with propylene include ethylene and α-olefins having 4 to 20 carbon atoms. Specific examples of the α-olefin include the following.
1-butene, 2-methyl-1-propene (above C ₄ ); 1-pentene, 2-methyl-1-butene, 3-methyl-1-butene (above C ₅ ); 1-hexene, 2-ethyl- 1-butene, 2,3-dimethyl-1-butene, 2-methyl-1-pentene, 3-methyl-1-pentene, 4-methyl-1-pentene, 3,3-dimethyl-1-butene ₆ ); 1-heptene, 2-methyl-1-hexene, 2,3-dimethyl-1-pentene, 2-ethyl-1-pentene, 2-methyl-3-ethyl-1-butene (above C ₇ ); 1-octene, 5-methyl-1-heptene, 2-ethyl-1-hexene, 3,3-dimethyl-1-hexene, 2-methyl-3-ethyl-1-pentene, 2,3,4-trimethyl- 1-pentene, 2-propyl-1-pentene, 2,3 Diethyl-1-butene (or C _8); 1-nonene (C _9); 1-decene (C _10); 1-undecene (C _11); 1-dodecene (C _12); 1-tridecene (C ₁₃₎ 1-tetradecene (C ₁₄ ); 1-pentadecene (C ₁₅ ); 1-hexadecene (C ₁₆ ); 1-heptadecene (C ₁₇ ); 1-octadecene (C ₁₈ ); 1-nonadecene (C ₁₉ ) and the like.

  Preferred among the α-olefins are α-olefins having 4 to 12 carbon atoms, specifically 1-butene, 2-methyl-1-propene; 1-pentene, 2-methyl-1- Butene, 3-methyl-1-butene; 1-hexene, 2-ethyl-1-butene, 2,3-dimethyl-1-butene, 2-methyl-1-pentene, 3-methyl-1-pentene, 4- Methyl-1-pentene, 3,3-dimethyl-1-butene; 1-heptene, 2-methyl-1-hexene, 2,3-dimethyl-1-pentene, 2-ethyl-1-pentene, 2-methyl- 3-ethyl-1-butene; 1-octene, 5-methyl-1-heptene, 2-ethyl-1-hexene, 3,3-dimethyl-1-hexene, 2-methyl-3-ethyl-1-pentene, 2,3,4-trimethyl-1-pen Ten, 2-propyl-1-pentene, 2,3-diethyl-1-butene; 1-nonene; 1-decene; 1-undecene; 1-dodecene and the like. From the viewpoint of copolymerizability, 1-butene, 1-pentene, 1-hexene and 1-octene are preferable, and 1-butene and 1-hexene are more preferable.

  The copolymer may be a random copolymer or a block copolymer. Preferred copolymers include propylene / ethylene copolymers and propylene / 1-butene copolymers. In the propylene / ethylene copolymer and the propylene / 1-butene copolymer, the ethylene unit content and the 1-butene unit content are, for example, 616 of “Polymer Analysis Handbook” (published by Kinokuniya, 1995). Infrared (IR) spectrum measurement can be performed by the method described on the page.

  From the viewpoint of improving the transparency and workability of the retardation film, it is preferable to use a random copolymer obtained by random copolymerization of an arbitrary unsaturated hydrocarbon with propylene as a main monomer. Of these, a copolymer with ethylene is preferred. When making a copolymer, it is advantageous that unsaturated hydrocarbons other than propylene have a copolymerization ratio of about 1 to 10% by mass, and a more preferable copolymerization ratio is 3 to 7% by mass. It is preferable that the amount of units of unsaturated hydrocarbons other than propylene be in the above-mentioned range since the workability and transparency of the film are improved without drastically reducing the heat resistance due to the lowering of the melting point of the resin. In addition, when setting it as the copolymer of two or more types of comonomers, and a polypropylene, it is preferable that the total content of the unit derived from all the comonomers contained in the copolymer is the said range.

  The polypropylene resin used for producing the polypropylene polymer film has a melt flow rate (MFR) measured at a temperature of 230 ° C. and a load of 21.18 N in accordance with JIS K-7210 of 0.1 to 200 g / It is preferably 10 minutes, and more preferably 0.5 to 50 g / 10 minutes. By using a polypropylene resin having an MFR in this range, a uniform film can be obtained without imposing a large load on the extruder.

  The polypropylene resin can be produced by a method of homopolymerizing propylene using a known polymerization catalyst or a method of copolymerizing propylene and another copolymerizable comonomer. As a known polymerization catalyst, for example, a Ti—Mg catalyst comprising a solid catalyst component containing magnesium, titanium and halogen as essential components; a solid catalyst component containing magnesium, titanium and halogen as essential components; And a catalyst system in combination with a third component such as an electron-donating compound, if necessary, and a metallocene catalyst.

  Among these catalyst systems, a combination of an organic aluminum compound and an electron donating compound with a solid catalyst component containing magnesium, titanium and halogen as essential components is preferable. Examples of the organoaluminum compounds include triethylaluminum, triisobutylaluminum, a mixture of triethylaluminum and diethylaluminum chloride, tetraethyldialumoxane, etc .; and examples of electron donating compounds include cyclohexylethyldimethoxysilane, tert -Butylpropyldimethoxysilane, tert-butylethyldimethoxysilane, dicyclopentyldimethoxysilane and the like are included.

  On the other hand, examples of solid catalyst components containing magnesium, titanium and halogen as essential components include catalysts described in JP-A-61-218606, JP-A-61-287904, JP-A-7-216017, and the like. Examples of metallocene catalysts include the catalyst systems described in Japanese Patent No. 2587251, Japanese Patent No. 2627669, Japanese Patent No. 2668732, and the like.

  The polypropylene resin can be produced by various methods. For example, solution polymerization using an inert solvent typified by hydrocarbon compounds such as hexane, heptane, octane, decane, cyclohexane, methylcyclohexane, benzene, toluene, xylene, bulk polymerization using a liquid monomer as a solvent, gas It can be produced by a gas phase polymerization method in which the monomer is polymerized as it is. Polymerization by these methods may be carried out batchwise or continuously.

  The stereoregularity of the polypropylene resin may be any of isotactic, syndiotactic, and atactic. In the present invention, it is preferable to use a syndiotactic or isotactic polypropylene resin from the viewpoint of heat resistance and crystallinity in the resin.

  In the present invention, it is preferable to use a film containing a polypropylene-based resin as a main raw material as a retardation film. However, the film contains one kind selected from various additives as long as the effects of the present invention are not impaired. The above may be added. Examples of the additive include an antioxidant, an ultraviolet absorber, an antistatic agent, a lubricant, a nucleating agent, an antifogging agent, and an antiblocking agent. Antioxidants include, for example, phenolic antioxidants, phosphorus antioxidants, sulfur antioxidants, hindered amine light stabilizers, etc., and, for example, a phenolic antioxidant mechanism in one molecule A composite antioxidant having a unit having a phosphorus-based antioxidant mechanism can also be used. Examples of the UV absorber include UV absorbers such as 2-hydroxybenzophenone and hydroxyphenylbenzotriazole, and benzoate UV blockers. The antistatic agent may be polymer type, oligomer type or monomer type. Examples of the lubricant include higher fatty acid amides such as erucic acid amide and oleic acid amide, higher fatty acids such as stearic acid, and salts thereof. Examples of the nucleating agent include sorbitol nucleating agents, organophosphate nucleating agents, and polymer nucleating agents such as polyvinylcycloalkane. As the anti-blocking agent, fine particles having a spherical shape or a shape close thereto can be used regardless of inorganic type or organic type. A plurality of these additives may be used in combination.

  Polypropylene resin can be formed by any method (hereinafter, the film after film formation is referred to as “raw film”). This raw film is transparent and has substantially no in-plane retardation. For example, a polypropylene system having substantially no in-plane retardation by extrusion molding from molten resin, solvent casting method in which a resin dissolved in an organic solvent is cast on a flat plate, and the solvent is removed to form a film. A resin raw film can be obtained.

  An example of a method for producing a raw film by extrusion is as follows. A polypropylene resin is melt-kneaded by rotation of a screw in an extruder and extruded from a T die into a sheet. The temperature of the molten sheet to be extruded is about 180 to 300 ° C. If the temperature of the molten sheet at this time is lower than 180 ° C., the spreadability is not sufficient, the thickness of the obtained film becomes non-uniform, and there is a possibility that the film has a phase difference unevenness. Further, when the temperature exceeds 300 ° C., the resin is easily deteriorated or decomposed, and bubbles may be generated in the sheet or carbides may be contained. The extruder may be a single screw extruder or a twin screw extruder. For example, in the case of a single screw extruder, L / D, which is the ratio of the screw length L to the diameter D, is about 24 to 36, the screw groove space volume in the resin supply unit, and the screw groove space volume in the resin metering unit The compression ratio, which is the ratio (the former / the latter), is about 1.5 to 4, and a screw such as a full flight type, a barrier type, and a type having a Maddock type kneading portion can be used. From the viewpoint of suppressing deterioration and decomposition of the polypropylene resin and uniformly melting and kneading, a barrier type screw having an L / D of 28 to 36 and a compression ratio of 2.5 to 3.5 is used. preferable. Moreover, in order to suppress deterioration and decomposition | disassembly of polypropylene resin as much as possible, it is preferable to make the inside of an extruder into nitrogen atmosphere or a vacuum. Furthermore, in order to remove the volatile gas generated by the deterioration or decomposition of the polypropylene resin, it is also preferable to provide an orifice of 1 mmφ to 5 mmφ at the tip of the extruder to increase the resin pressure at the tip of the extruder. Increasing the resin pressure at the tip of the extruder at the orifice means increasing the back pressure at the tip, thereby improving the stability of extrusion. The diameter of the orifice to be used is more preferably 2 mmφ or more and 4 mmφ or less.

The T-die used for extrusion preferably has no fine steps or scratches on the resin flow path surface, and the lip portion is plated or coated with a material having a low coefficient of friction with the molten polypropylene resin. Further, a sharp edge shape with a lip tip polished to 0.3 mmφ or less is preferable. Examples of the material having a small friction coefficient include tungsten carbide type and fluorine type special plating. By using such a T-die, it is possible to suppress the occurrence of eye cracks and at the same time to suppress the die line, so that a resin film having excellent appearance uniformity can be obtained. In the T-die, the manifold has a coat hanger shape and preferably satisfies the following condition (1) or (2), and more preferably satisfies the condition (3) or (4).
When the lip width of the T die is less than 1500mm: Length in the thickness direction of the T die> 180mm (1)
When the lip width of the T die is 1500 mm or more: T die thickness direction length> 220 mm (2)
When the lip width of the T die is less than 1500 mm: Length in the height direction of the T die> 250 mm (3)
When the lip width of the T die is 1500mm or more: Length in the height direction of the T die> 280mm (4)
By using a T die that satisfies the above conditions, the flow of the molten polypropylene resin inside the T die can be adjusted, and the lip portion can be extruded while suppressing thickness unevenness. An original film having excellent and more uniform retardation can be obtained.

  From the viewpoint of suppressing the extrusion fluctuation of the polypropylene resin, it is preferable to attach a gear pump via an adapter between the extruder and the T die. In addition, it is preferable to attach a leaf disk filter to remove foreign substances in the polypropylene resin.

  The molten sheet extruded from the T-die is between a metal cooling roll (also referred to as a chill roll or a casting roll) and a touch roll including an elastic body that presses and rotates in the circumferential direction of the metal cooling roll. A desired film can be obtained by clamping and solidifying by cooling. In this case, the touch roll may be one in which an elastic body such as rubber is directly on the surface, or may be one in which the surface of the elastic body roll is covered with an outer cylinder made of a metal sleeve. When using a touch roll in which the surface of the elastic roll is covered with an outer cylinder made of a metal sleeve, the molten sheet of polypropylene resin is directly sandwiched between the metal cooling roll and the touch roll for cooling. On the other hand, in the case of using a touch roll whose surface is an elastic body, a biaxially stretched film of a thermoplastic resin can be interposed between the molten sheet of polypropylene resin and the touch roll for sandwiching.

  When the molten sheet of polypropylene resin is sandwiched between the cooling roll and the touch roll as described above and cooled and solidified, both the cooling roll and the touch roll have their surface temperatures lowered, and the molten sheet is rapidly cooled. I need to do it. Specifically, the surface temperature of both rolls is adjusted to a range of 0 ° C. or higher and 30 ° C. or lower. When these surface temperatures exceed 30 ° C., it takes time to cool and solidify the molten sheet, so that the crystal component in the polypropylene resin grows, and the resulting film is inferior in transparency. The surface temperature of the roll is preferably less than 30 ° C, more preferably less than 25 ° C. On the other hand, when the surface temperature of the roll is less than 0 ° C., condensation occurs on the surface of the metallic cooling roll, and water droplets adhere to the surface, which tends to deteriorate the appearance of the film.

  Since the surface state of the metal cooling roll used is transferred to the surface of the polypropylene resin film, there is a possibility that the thickness accuracy of the resulting polypropylene resin film may be lowered if the surface is uneven. . Therefore, it is preferable that the surface of the metal cooling roll is in a mirror surface state as much as possible. Specifically, the roughness of the surface of the metal cooling roll is preferably 0.3S or less, more preferably 0.1S to 0.2S, expressed in the standard sequence of the maximum height. .

  The touch roll forming the nip portion with the metal cooling roll has a surface hardness of 65 to 80 as a value measured by a spring hardness test (A type) defined in JIS K-6301. It is preferable that there is, more preferably 70-80. By using a rubber roll having such a surface hardness, it becomes easy to maintain a uniform linear pressure applied to the molten sheet, and a bank of the molten sheet (resin pool) is provided between the metal cooling roll and the touch roll. ) Can be easily formed into a film.

  The pressure (linear pressure) when sandwiching the molten sheet is determined by the pressure for pressing the touch roll against the metal cooling roll. The linear pressure is preferably 50 N / cm or more and 300 N / cm or less, and more preferably 100 N / cm or more and 250 N / cm or less. By setting the linear pressure within the above range, it becomes easy to produce a polypropylene resin film while maintaining a constant linear pressure without forming a bank.

  When a biaxially stretched film of a thermoplastic resin is sandwiched between a metallic cooling roll and a touch roll together with a molten sheet of polypropylene resin, the thermoplastic resin constituting the biaxially stretched film is strong with the polypropylene resin. Any resin may be used as long as it is not heat-sealed, and specific examples include polyester, polyamide, polyvinyl chloride, polyvinyl alcohol, ethylene-vinyl alcohol copolymer, and polyacrylonitrile. Among these, polyesters that have little dimensional change due to humidity, heat, and the like are most preferable. In this case, the thickness of the biaxially stretched film is usually about 5 to 50 μm, preferably 10 to 30 μm.

  In this method, the distance (air gap) from the lip of the T die to the pressure between the metal cooling roll and the touch roll is preferably 200 mm or less, and more preferably 160 mm or less. The molten sheet extruded from the T-die is stretched from the lip to the roll, and orientation tends to occur. By shortening the air gap as described above, a film having a smaller orientation can be obtained. The lower limit of the air gap is determined by the diameter of the metal cooling roll to be used, the diameter of the touch roll, and the tip shape of the lip to be used, and is usually 50 mm or more.

  The processing speed when producing a polypropylene resin film by this method is determined by the time required for cooling and solidifying the molten sheet. When the diameter of the metal cooling roll to be used is increased, the distance at which the molten sheet is in contact with the cooling roll becomes longer, so that production at a higher speed is possible. Specifically, when a 600 mmφ metal cooling roll is used, the processing speed is about 5 to 20 m / min at the maximum.

  The molten sheet sandwiched between the metal cooling roll and the touch roll is cooled and solidified by contact with the roll. And after slitting an edge part as needed, it is wound up by a winder and becomes a film. Under the present circumstances, in order to protect the surface until it uses a film, you may wind up in the state which bonded the surface protection film which consists of another thermoplastic resin to the single side | surface or both surfaces. When a molten sheet of polypropylene resin is sandwiched between a metal cooling roll and a touch roll together with a biaxially stretched film made of a thermoplastic resin, the biaxially stretched film is used as one surface protective film. You can also.

The raw film produced by the above method or the like can be used as a retardation film as it is. Moreover, it can also be used as a retardation film after performing any one of the following treatments or two or more of them.
<Extension processing>
In order to develop the retardation of the raw film, a stretching process can be performed. A film exhibiting biaxial birefringence by biaxial stretching can be used as the retardation film. The stretching ratio is about 1.1 to 10 times in the direction in which the optical axis is expressed (the direction in which the stretching ratio is large and becomes the slow axis), in the longitudinal direction and the transverse direction (stretching direction). The direction can be selected as appropriate according to the required phase difference value from a range of about 1.1 to 7 times in the direction in which the magnification is small and becomes the fast axis. The optical axis may be developed in the lateral direction of the film, or the optical axis may be developed in the longitudinal direction.

<Easy adhesion treatment>
Adhesiveness with the optically anisotropic layer formed on the surface of the retardation film made of the polypropylene resin or containing the polypropylene resin, or an alignment film formed as desired In order to improve this, it is preferable to perform an easy adhesion treatment. By performing this treatment, even when exposed to high heat and high humidity, peeling with other optical films, polarizers, liquid crystal cells and the like hardly occurs, and heat resistance is improved. As the easy adhesion treatment, corona discharge treatment or atmospheric pressure plasma treatment is preferred. Corona discharge treatment is also roughly classified into atmospheric pressure plasma treatment, but here, what directly exposes the workpiece to the plasma region by corona discharge is called corona discharge treatment, and the plasma region and the surface of the workpiece are separated. This is called atmospheric pressure plasma treatment. Although corona treatment has many industrial practical examples and is low in cost, it has a demerit that physical damage on the surface of the treatment body is large. On the other hand, there are relatively few practical examples of atmospheric pressure plasma treatment, and the cost is higher than that of corona treatment, but there is an advantage that the treatment body surface is less damaged and treatment intensity can be set relatively high. Therefore, the preferable processing method may be selected from the relationship between the damage of the polymer film to be used and the improvement level of the adhesiveness after the processing.

The treated surface of the film subjected to these treatments becomes hydrophilic. As an indication of hydrophilization, the contact angle of water on the treated surface may be used. Specifically, the contact angle of water on the treated surface is preferably 55 ° or less, and more preferably 50 ° or less. When the contact angle of water on the treated surface is in the above range, the adhesion with the polarizer and other optical films and with the optically anisotropic layer or alignment film formed thereon is improved. Defects are less likely to occur. Although there is no restriction | limiting in particular about a lower limit, It is preferable to set so that a polymer film may not be damaged. The contact angle can be measured according to JIS R-3257 (1999). In the corona discharge treatment and the atmospheric pressure plasma treatment, treatment conditions are determined so that the contact angle is in the above range. The processing conditions to be varied include applied voltage, frequency, atmospheric gas type, processing time, etc. in any processing method.
For details of these treatments, see Polymer Surface Modification (Modern Editorial Company), p. 88- Basics and applications of polymer surfaces (bottom) (Chemical Doujin) 31--Principles / characteristics of atmospheric pressure plasma and polymer film / glass substrate surface modification technology (Technical Information Association), etc. are described respectively, and the contents thereof can be referred to.

《Dust removal process》
The surface of the film, particularly the surface that has been subjected to corona discharge treatment or atmospheric pressure plasma treatment (hereinafter sometimes referred to as “treated surface”) is preferably subjected to dust removal treatment before forming a layer thereon. The dust removal method is not particularly limited. Ultrasonic dust removal using ultrasonic waves is preferred. The ultrasonic dust removal is described in detail in JP-A-7-333613 and can be referred to.
Moreover, when forming the alignment film mentioned later, it is preferable to perform a dust removal process after performing the rubbing process on the surface of the alignment film.

<Swelling treatment>
When a coating layer such as a liquid crystal composition is formed on the film, the coating solvent in the coating composition of the layer formed adjacent to the film causes the film to swell to some extent, thereby It is also possible to improve adhesion. Specifically, the adhesiveness can be preferably improved without causing whitening of the coating layer by using a solvent in which a solvent capable of swelling the film and a solvent that does not swell are mixed at a predetermined ratio.

  Various polymer films used as retardation films for the rear side and front side retardation regions 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 films for the rear side and front side retardation regions may be films produced by being stretched after being formed. 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 layer constituting the rear side and front side retardation regions may be a layer formed by fixing the alignment state after setting the liquid crystal composition to a desired alignment state, or It may be a laminate having a polymer film that supports the layer together with the layer. 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 producing the retardation layer constituting the front side retardation region include various liquid crystals such as a rod-like liquid crystal, a disk-like liquid crystal, and a cholesteric liquid crystal.

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 acetate solution (dope) for each layer is prepared. In the co-casting method (multi-layer simultaneous casting), the dope for casting of each layer (which may be three layers or more) is 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.

In order to obtain a higher front CR, the haze of the retardation layer constituting the rear side and front side retardation regions is preferably 0.5 or less, more preferably 0.3 or less, and even more preferably 0.2 or less. .
In addition, in this specification, the measuring method of the haze of a phase difference layer is as follows. A retardation layer sample of 40 mm × 80 mm is prepared and measured in accordance with 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.

  In addition, the thickness of the retardation layer constituting the rear side and front side retardation regions is preferably thin, but 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. is there. The film thickness of the rear side retardation film is preferably 20 μm or more and 200 μm or less from the viewpoint of suppressing corner unevenness and manufacturing suitability. Note that corner unevenness is described in detail in JP-A-2009-69720.

2. 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 the iodine or dichroic dye to penetrate into the binder. Is common.

3. 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, the protective film disposed on the liquid crystal cell side constitutes a part of the rear side retardation region and the front side retardation region, respectively, and the former is required to satisfy the above formula (I). The The latter also constitutes a part of the front-side retardation region, and depending on the mode, it is required to show optical characteristics that contribute to the improvement of the viewing angle CR alone or with other layers.

  There is no restriction | limiting in particular about the protective film arrange | positioned on the outer side of a front side polarizer and a rear side polarizer. Various polymer films can be used. This is the same as the example of the polymer film that can constitute the front side retardation region. For example, cellulose acylates (eg, films of cellulose acetate, cellulose propionate, cellulose butyrate, etc.), polyolefins (eg, norbornene polymers), poly (meth) acrylic acid esters (eg, polymethyl methacrylate), polycarbonate , Polyester, or a film mainly composed of polysulfone, but is not limited thereto. 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 19 (1) Production of Film 1 Cellulose acylate of the acyl group type and substitution degree shown in the following table was 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 the table, Ac is an acetyl group, and CTA means cellulose triacetate (a cellulose ester derivative in which an acyl group is composed 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 ――――――――――――――――――――――――――――――――――
CTA in the following table 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.
Here, the abbreviations of the additives and plasticizers in the table and the above 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.

  The cellulose acylate film thus produced was used as film 1.

(2) Production of Film 2 A commercially available norbornene-based polymer film “ZEONOR ZF14-100” (manufactured by Optes Co., Ltd.) is 1.55 times in the MD direction (same as the longitudinal direction) at a temperature of 142 ° C., in the TD direction ( After biaxial stretching at a fixed end of 1.8 times in the width direction), the surface was subjected to corona discharge treatment by a solid state corona treatment machine 6KVA (manufactured by Pillar Co., Ltd.). This film was used as film 2. The thickness of this film was 38 μm.

(3) Production of Film 3 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) % And mixed for 30 minutes with a tumbler mixer. The obtained mixture was dried by 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 3. The film thickness of this film was 72 μm.
In this example, a film using cellulose acylate propionate showed an example of production by melt extrusion. However, the same effect was obtained by solution casting (in consideration of solubility, the degree of acetyl substitution is 1. 6, cotton with a propionyl substitution degree of 0.9 was used).

(4) Production of film 4 2,2′-bis (3,4-dicarboxyphenyl) in a reaction vessel (500 mL) equipped with a mechanical stirrer, Dean-Stark device, nitrogen introduction tube, thermometer and cooling tube -17.77 g (40 mmol) of hexafluoropropane dianhydride and 12.81 g (40 mmol) of 2,2-bis (trifluoromethyl) -4,4'-diaminobiphenyl were added. Subsequently, a solution in which 2.58 g (20 mmol) of isoquinoline was dissolved in 275.21 g of m-cresol was added, and the mixture was stirred at 23 ° C. for 1 hour (600 rpm) to obtain a uniform solution. Next, the reaction vessel was heated using an oil bath so that the temperature in the reaction vessel became 180 ± 3 ° C., and stirred for 5 hours while maintaining the temperature to obtain a yellow solution. After further stirring for 3 hours, heating and stirring were stopped, and the mixture was allowed to cool and returned to room temperature. As a result, the polymer precipitated as a gel.

  Acetone was added to the yellow solution in the reaction vessel to completely dissolve the gel-like material to prepare a diluted solution (7% by weight). When this diluted solution was gradually added to 2 L of isopropyl alcohol while stirring, a white powder was precipitated. This powder was collected by filtration and poured into 1.5 L of isopropyl alcohol for washing. Further, the same operation was repeated once again for washing, and then the powder was again collected by filtration. This was dried in a 60 ° C. air circulation type constant temperature oven for 48 hours, and then dried at 150 ° C. for 7 hours to obtain a polyimide composed of repeating units represented by the following formula (1) as a white powder (yield: 85 %). The polyimide had a polymerization average molecular weight (Mw) of 124,000 and an imidation ratio of 99.9%.

  17.7 parts by weight of the produced polyimide (white powder) was dissolved in 100 parts by weight of methyl isobutyl ketone (boiling point 116 ° C.) to prepare a 15% by weight polyimide solution. This polyimide solution was applied in one direction with a rod coater on the surface of the anchor coat layer of the transparent film having the anchor coat layer. Next, it was dried in a 135 ± 1 ° C. air circulating constant temperature oven for 5 minutes to evaporate the solvent, and a transparent film (total thickness: 83.8 μm) having a 3.0 μm thick polyimide layer was produced. Subsequently, while heating the transparent film provided with the polyimide layer in an air circulating constant temperature oven at 150 ± 1 ° C., the longitudinal direction of the film was fixed using a tenter stretching machine and the width direction was 1.22 times. After uniaxial stretching, a relaxation treatment was applied at 0.97 times in the width direction to produce a laminated film. This laminated film after stretching was used as film 4.

(5) Production of Film 5 The following composition was put into a mixing tank, stirred while heating 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, and cellulose. An 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 (2) 7.0 parts by mass Methylene chloride 428.4 parts by mass Methanol 64.0 parts by mass

  The composition of the retardation developer (2) is shown in the following table. In the table 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 (2) is a non-phosphate ester compound and also a retardation developer. The end of the retardation developer (2) is sealed with an acetyl group.

  The 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 tenter conveyance to roll conveyance, and further dried and wound at 110 ° C. to 150 ° C. to produce a film 5. The film thickness of this film was 83 μm.

In the production of the film 5, problems that occur during the production of the film 1 (smoke during high-temperature treatment in the drying process, malfunction of operation due to adhesion of the manufacturing machine such as volatilized oil, and surface failure due to film adhesion) do not occur It was.
This is because the retardation developing agent (2) used as the retardation developing agent functions as a plasticizer in the production of the film 5, 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 (2), the positive birefringent compound is used from the viewpoint of film production. To a preferable retardation developer.

(6) Production of film 6 (cellulose acylate solution for low substitution layer)
The following composition was put into a mixing tank, stirred while heating 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 prepare a cellulose acylate solution.
(Cellulose acylate solution)
Cellulose acetate with a degree of substitution of 2.43 100 parts by weight Retardation agent (3) 18.5 parts by weight Methylene chloride 365.5 parts by weight Methanol 54.6 parts by weight

  The composition of the retardation developer (3) is shown in the following table. In the table below, 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. Yes. The retardation developer (3) is a non-phosphate ester compound and also a retardation developer. The end of the retardation developer (3) 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 developing agent (3) 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)
The cellulose acylate solution for the low substitution layer is a core layer having a thickness of 70 μm, and the cellulose acylate solution for the high substitution layer is a skin A layer and a skin B layer having a thickness of 2 μm, respectively. Casted. The obtained film was peeled from the band, sandwiched between clips, and stretched in the transverse direction using a tenter at a stretching temperature of 180 ° C. in the width direction at a stretch temperature of 180 ° C. when the residual solvent amount was 20%. Thereafter, the clip was removed from the film and dried at 130 ° C. for 20 minutes to produce a film 6.

(7) Production of film 7 A film except that the cellulose acylate shown in the following table was used, the addition amount of the retardation enhancer (1) was changed as shown in the following table, and the stretching treatment was carried out under different stretching conditions. In the same manner as in Example 1, a cellulose acylate film was prepared. This film was used as film 7. In addition, about the abbreviation of the following additive and plasticizer, it is synonymous with the above.

(8) Production of film 8 In the production of film 7, the amount of addition of retardation enhancer (1) is the same as film 7 except that 1.4 parts by mass is replaced with 1.5 parts by mass. A rate film was prepared. This film was used as film 8.

(9) Preparation of Film 9 A commercially available cellulose acylate film, trade name “Z-TAC” (manufactured by Fuji Film Co., Ltd.) was prepared and used as film 9.

(10) Production of Film 10 A stretched film (protective film A) was produced according to the description in [0223] to [0226] of JP-A-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.

(11) Production of Film 11 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 11. The thickness of this film was 60 μm.

(12) Production of Film 12 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 for film 11. This film was used as film 12. The thickness of this film was 50 μm.

(13) Preparation of Film 13 A commercially available cellulose acylate film, trade name “TD80UL” (manufactured by FUJIFILM Corporation) was prepared and used as the film 13.

(14) Production of film 14 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 the production conditions were changed as shown in the following table. A film was prepared and used as film 14. In addition, the abbreviations of the following additives and plasticizers are as defined above.

(15) Preparation of Film 15 In the method for synthesizing compound C-3 for comparison described in JP-A-2008-95027, the same method except that 4-methoxycinnamic acid chloride used for intermediate 2 was changed to benzoyl chloride Thus, cellulose acetate benzoate 15A was synthesized.

<Preparation of cellulose acylate solution>
The following raw materials were put into a mixing tank, stirred while heating, dissolved, and a solution having a cellulose acylate solution was prepared.
―――――――――――――――――――――――――――――――――
Cellulose acylate solution ――――――――――――――――――――――――――――――――――
Cellulose acetate benzoate 15A 100.0 parts by mass Methylene chloride 403.0 parts by mass Methanol 60.2 parts by mass ――――――――――――――――――――――――――― ―――――

The prepared cellulose acylate solution was quickly cast with a band casting machine. A film having a residual solvent amount of about 30% by mass was dried by applying hot air at 160 ° C. with a tenter.

  Further, this film was fixed-end uniaxially stretched at a temperature of 160 ° C. by 1.5 times to produce a film 15. The film thickness of this film was 55 μm.

(16) Production of Film 16 <Synthesis of Cyclic Polyolefin Polymer P-1>
100 parts by mass of purified toluene and 100 parts by mass of norbornene carboxylic acid methyl ester were charged into a reaction kettle. Next, ethylhexanoate-Ni 25 mmol% (to monomer) dissolved in toluene, tri (pentafluorophenyl) boron 0.225 mol% (to monomer) and triethylaluminum 0.25 mol% (to monomer) dissolved in toluene were reacted. I put it in the kettle. The reaction was allowed to proceed for 18 hours at room temperature with stirring. After completion of the reaction, the reaction mixture was put into excess ethanol to produce a polymer precipitate. The cyclic polyolefin polymer (P-1) obtained by purifying the precipitate was vacuum dried at 65 ° C. for 24 hours.

  The obtained polymer was dissolved in tetrahydrofuran and measured for molecular weight by gel permeation chromatography. The number average molecular weight in terms of polystyrene was 79,000 and the weight average molecular weight was 205,000. The refractive index of the obtained polymer measured by Abbe's refractometer was 1.52.

(Polyolefin dope D-1)
Cyclic polyolefin polymer P-1 150 parts by mass additive: polymethyl acrylate (“Act Flow UMM1001” manufactured by Soken Chemical Co., Ltd.)
Weight average molecular weight Mw≈1000) 7.5 parts by mass degradation inhibitor: “IRGANOX1010” manufactured by Ciba Specialty Chemicals
0.45 parts by mass dichloromethane 620 parts by mass

  The above composition was put into a mixing tank and stirred 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 prepare cyclic polyolefin dope D-1. The dope was cast with a band casting machine. The film having a residual solvent amount of about 30% by mass and peeled off from the band was dried by applying hot air of 140 ° C. with a tenter. Then, the tenter transport was shifted to the roll transport, and further dried at 120 to 140 ° C. and wound up. This was used as film 16. The film thickness was 80 μm.

(17) Production of film 17 (cellulose substitution solution for low substitution degree layer)
The following composition was put into a mixing tank, stirred while heating to dissolve each component, and a cellulose acylate solution for a low substitution degree 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 (3) 10.0 parts by weight methylene chloride 351.5 parts by weight Methanol 52.5 parts by weight

(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 developing agent (3) 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)
The cellulose acylate solution for the low substitution layer is a core layer having a thickness of 82 μm, and the cellulose acylate solution for the high substitution layer is a skin A layer and a skin B layer having a thickness of 2 μm. Each was cast. The obtained film was peeled off from the band and sandwiched between clips. When the amount of residual solvent relative to the total mass of the film was 20%, the film was stretched laterally 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 film 17.

(18) Preparation of film 18 (cellulose acylate solution for low substitution layer)
The following composition was put into a mixing tank, stirred while heating to dissolve each component, and a cellulose acylate solution for a low substitution degree layer was prepared.
Cellulose acetate having a degree of substitution of 2.43 100 parts by mass Retardation agent (3) 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 developing agent (3) 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)
The cellulose acylate solution for the low substitution degree layer becomes a core layer with a film thickness of 38 μm, and the cellulose acylate solution for the high substitution degree layer becomes a skin A layer and a skin B layer with a film thickness of 2 μm, respectively. Casted. The obtained film was peeled from the band, and when the amount of residual solvent relative to the mass of the entire 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 18.

(19) Production of film 19 (cellulose acylate solution for low substitution layer)
The following composition was put into a mixing tank, stirred while heating to dissolve each component, and a cellulose acylate solution for a low substitution degree layer was prepared.
Cellulose acetate having a degree of substitution of 2.43 100 parts by mass Retardation agent (3) 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 developing agent (3) 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)
The cellulose acylate solution for the low substitution layer is a core layer having a thickness of 60 μm, and the cellulose acylate solution for the high substitution layer is a skin A layer and a skin B layer having a thickness of 2 μm. Each was cast. The obtained film was peeled from the band, sandwiched between clips, and stretched in the width direction at a stretching temperature of 200 ° C. and 70% in the width direction using a tenter when the amount of residual solvent relative to the total mass of the film was 20%. Thereafter, the clip was removed from the film and dried at 130 ° C. for 20 minutes to produce a film 19.

2. Properties of Films 1-19 The properties of the prepared films 1-19 are summarized in the following table. Re (550) and Rth (550) of each film were measured at a wavelength of 550 nm in KOBRA21ADH (manufactured by Oji Scientific Instruments) by conditioning a sample 30 mm × 40 mm for 2 hours at 25 ° C. and 60% RH. And about the films 1, 3, 5-9, 13-15, and 17-19, it calculated by inputting the assumed value 1.48 of an average refractive index, and a film thickness. In the case of other films, the assumed average refractive index is 1.53 for films 2 and 11, 1.58 for film 4, 1.50 for film 10, and films 12 and 16 About 1.52 was used.

3. 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 shown in the above table, the film containing cellulose acylates was immersed in an aqueous sodium hydroxide solution at 55 mol C at 1.5 mol / liter, and then the sodium hydroxide was sufficiently 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 polarizing plate having a protective film on both surfaces was prepared by sandwiching a polarizing film between any two of the films (films 1 to 19) and using an adhesive. In addition, about the cellulose acylate type | system | group film, the polyvinyl-type adhesive was used, and about the other film, it bonded with the polarizer using the acrylic adhesive.
For films 1-6 and 14-17, 19, the in-plane slow axis is bonded in parallel with the transmission axis of the polarizer; for films 7-13, 18, the in-plane slow axis is Bonding was performed perpendicular to the transmission axis of the polarizer.
The combinations are shown in the table below. In addition, in the following table | surface, the film which attached | subjected "* 1" means the retardation film used as a polarizing plate protective film arrange | positioned further on the display surface side outer side from a polarizing film, and the film which attached "* 2" Means a retardation film used as a polarizing plate protective film disposed between the liquid crystal cell and the polarizing film, and the film marked with “* 3” is disposed further outside the polarizing film than the polarizing film. It means a retardation film used as a polarizing protective film.

4). Production and Evaluation of VA Type Liquid Crystal Display Device (1) Preparation of VA Type Liquid Crystal Cell 1 A liquid crystal panel “KDL-52W5” manufactured by Sony Corporation was prepared. This is a VA type liquid crystal panel having a COA structure. The liquid crystal panel was disassembled and reassembled with the front and back surfaces of the taken out liquid crystal cell reversed, that is, the COA substrate was disposed as the front side substrate and reassembled, and this was used as the liquid crystal cell 1.
When Δnd of the liquid crystal cell 1 was measured using AXOSCAN manufactured by AXOMETRIC and the attached software, Δnd (550) was 295 nm.

(2) Preparation of VA liquid crystal cells 2 and 3 As in Example 1 of JP-A-11-326606, a black resin layer was applied on a glass substrate. However, a slit coater was used by adjusting the viscosity of the black resin for coating, and a mask made in combination with the TFT element pattern was used for exposure.
A TFT element was produced on the black resin of the glass substrate according to Example 20 of JP2009-141341A, and a protective film was further formed on the TFT element.
Subsequently, a composition prepared as described in Examples 3, 8 and 10 described in JP-A-2009-144126 was used as the colored photosensitive composition on the protective film, respectively, and Special Table 2008- A color filter on array (COA) substrate was produced according to the process described in Example 9a described in [0099] to [0103] of Japanese Patent No. 516262. However, the concentration of the pigment in the colored photosensitive resin composition of each pixel is halved and the coating amount is adjusted so that the black pixel is 4.2 μm and the red, green, and blue pixels are all 3.5 μm. 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. 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.
Separately, a glass substrate on which an ITO transparent electrode was formed was prepared as a counter substrate, the COA 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. .
After that, a UV curable resin sealing agent is applied by a dispenser method to a position corresponding to the outer periphery of the black matrix provided around the RGB pixel group of the color filter, and a PVA mode liquid crystal is dropped, After bonding, the bonded substrate was irradiated with UV, and then heat treated to cure the sealant. A liquid crystal cell was thus produced.

The KDL-52W5 backlight is used as the light source, and the light source is arranged on the counter substrate side, that is, the liquid crystal cell whose front side substrate is a COA substrate is the liquid crystal cell 2, and the light source is arranged on the COA substrate side. That is, a liquid crystal cell in which the rear substrate is a COA substrate was used as the liquid crystal cell 3.
When Δnd of the produced liquid crystal cells 2 and 3 was measured using AXOSCAN manufactured by AXOMETRICS and the attached software, Δnd (550) was 295 nm.

(3) Preparation of Liquid Crystal Cell 4 A black resin layer was applied on a glass substrate in the same manner as in Example 1 of JP-A-11-326606. However, a slit coater was used by adjusting the viscosity of the black resin for coating, and a mask made in combination with the TFT element pattern was used for exposure.
A TFT element was produced on the black resin of the glass substrate according to Example 20 described in JP-A-2009-141341, and a protective film was further formed on the TFT element. Subsequently, after forming a contact hole in the protective film, an ITO transparent electrode electrically connected to the TFT element was formed on the protective film to produce an array substrate.
For the colored photosensitive composition, compositions prepared as described in Examples 3, 8 and 10 described in JP-A-2009-144126 were used, respectively, and [0099] to [0099] of JP-T-2008-516262. [0103] A color filter substrate was prepared according to the process described in Example 9a.
An ITO transparent electrode is formed by sputtering on the produced color filter substrate, and then in accordance with Example 1 of Japanese Patent Application Laid-Open No. 2006-64921, a portion corresponding to the upper part of the partition wall (black matrix) on the ITO film is formed. A spacer was formed.
The transparent electrodes of the prepared array substrate and color filter substrate were each patterned for the PVA mode, and an alignment film made of vertical polyimide was further provided thereon.
After that, a UV curable resin sealant is applied by a dispenser method to a position corresponding to the outer periphery of the black matrix provided around the RGB pixel group of the color filter, and a PVA mode liquid crystal is dropped, and the TFT substrate After the substrates were bonded together and irradiated with UV, the sealant was cured by heat treatment. In this way, a liquid crystal cell 4 was produced.

The KDL-52W5 backlight was used as the light source, and the light source was disposed on the TFT substrate side of the liquid crystal cell 4. That is, the liquid crystal cell 4 is a liquid crystal cell in which the rear substrate is a TFT substrate and the front substrate is a color filter substrate.
When Δnd of the produced liquid crystal cell 4 was measured using AXOSCAN manufactured by AXOMETRICS and the attached software, Δnd (550) was 295 nm.

(4) Preparation of liquid crystal cell 5 In the production of the COA substrate of the liquid crystal cell 2, the same method as the liquid crystal cell 2 except that a glass substrate without a black resin layer was used instead of the glass substrate coated with a black resin layer. Thus, a liquid crystal cell 5 was produced.
When Δnd of the produced liquid crystal cell 5 was measured using AXOSCAN manufactured by AXOMETRICS and the attached software, Δnd (550) was 295 nm.

(5) Preparation of the liquid crystal cell 6 The liquid crystal cell 6 is a liquid crystal except that a column spacer pattern formed in a portion corresponding to the upper part of the partition wall on the ITO film on the COA substrate is one having a diameter of 16 μm and an average height of 3.0 μm. A liquid crystal cell 6 was produced in the same manner as in the cell 2.
When Δnd of the produced liquid crystal cell 6 was measured using AXOSCAN manufactured by AXOMETRICS and the attached software, Δnd (550) was 240 nm.

(6) Preparation of liquid crystal cell 7 The column spacer pattern formed in the portion corresponding to the upper part of the partition wall on the ITO film on the color filter substrate, except that one having a diameter of 16 μm and an average height of 3.0 μm was used. A liquid crystal cell 7 was produced in the same manner as the liquid crystal cell 4.
When Δnd of the produced liquid crystal cell 7 was measured using AXOSCAN manufactured by AXOMETRICS and the attached software, Δnd (550) was 240 nm.

(7) Preparation of liquid crystal cells 8 and 9 A black resin layer was applied on a glass substrate in the same manner as in Example 1 described in JP-A-11-326606. However, a slit coater was used by adjusting the viscosity of the black resin for coating, and a mask made in combination with the TFT element pattern was used for exposure.
A TFT element was produced on the black resin of the glass substrate according to Example 20 of JP2009-141341A, and a protective film was further formed on the TFT element. Subsequently, after forming a contact hole in the protective film, an ITO transparent electrode electrically connected to the TFT element was formed on the protective film. Next, a transparent columnar spacer pattern having a diameter of 16 μm and an average height of 3.7 μm was formed on the ITO film, thereby preparing an array substrate.
Separately, a glass substrate on which an ITO transparent electrode was formed was prepared as a counter substrate, the array 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. .
A UV curable resin sealant is applied by a dispenser method in the same pattern as the liquid crystal cell 2 on the column spacers of the array substrate, and a PVA mode liquid crystal is dropped and bonded to the counter substrate, and then bonded. After the substrate was irradiated with UV, the sealant was cured by heat treatment. A liquid crystal cell was thus produced.
As a light source, a backlight unit that is driven and controlled so that BGR three-color LEDs alternately emit light at 180 Hz is prepared. The light source is arranged on the counter substrate side, the liquid crystal cell 8, and the light source is arranged on the array substrate side. Was designated as a liquid crystal cell 9.
When Δnd of the produced liquid crystal cells 8 and 9 was measured using AXOSCAN manufactured by AXOMETRICS and the attached software, Δnd (550) was 295 nm.

(8) Production of VA type liquid crystal display device A VA type liquid crystal display device was produced by bonding polarizing plates to the outer surfaces of both substrates of the above liquid crystal cell in the combinations shown in the following table. The polarizing plates were bonded with the absorption axes orthogonal to each other. In addition, about Example 14 shown in the following table | surface, the protective film is not bonded to the liquid crystal cell side of the polarizing plate arrange | positioned at the front side, The surface of a polarizer is a board | substrate of the liquid crystal cell 2 through an easily bonding layer. Bonded directly to the surface.
As described above, for the liquid crystal cells 1 to 7, the backlight unit of the liquid crystal panel “KDL-52W5” manufactured by Sony is used as the light source, and for the liquid crystal cells 8 and 9, BGR 3-color LEDs are alternately arranged at 180 Hz. A backlight unit that was driven and controlled to emit light was used.
The following evaluation was performed about each produced liquid crystal display device.

(9) Evaluation of VA liquid crystal display device About each liquid crystal display device, front contrast ratio, bright room visibility, and viewing angle contrast were evaluated by the following methods. The results are shown in the table below.
(9) -1 Measurement of front contrast ratio 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) is measured. (Luminance) 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 from the following formula based on the front contrast ratio in the reference form.
Front contrast ratio = Front contrast in each embodiment / Front contrast in reference form The reference form is
For the liquid crystal display device having the liquid crystal cell 1, the liquid crystal display device of Comparative Example 15 in the following table (front contrast 3700);
For the liquid crystal display device having each of the liquid crystal cells 2 to 5, the liquid crystal display device of Comparative Example 5 in the following table (front contrast is 3300);
A liquid crystal display device having liquid crystal cells 6 and 7 is a liquid crystal display device of Comparative Example 17 in the following table (front contrast is 2700); and a liquid crystal display device having liquid crystal cells 8 and 9 is a liquid crystal of Comparative Example 18 in the following table Display device (front contrast is 3850);
It was.

(9) -2 Measurement of bright room contrast Bright room contrast is the front contrast in a bright room.
A trade name “CV-LU” (manufactured by Fuji Film Co., Ltd.) was bonded to the outermost surface of each liquid crystal display device, and the light room contrast was evaluated.
In a room with a white wall, each liquid crystal display device was placed on a table, and an illuminance meter was horizontally placed 10 cm forward from the center of the screen to adjust the illuminance of the room so that the illuminance was 200 lux. Thereafter, the distance between the measuring instrument and the panel is set to 700 mm, and the luminance values of the black display and the white display in the normal direction of the panel are measured, and the bright room contrast (white luminance in the bright room / black luminance in the bright room). ) Was calculated and evaluated as follows.
○: Bright room contrast is 500 or more. Δ: Bright room contrast is less than 500. 100 or more. X: Bright room contrast is less than 100. A level of more than Δ.

(9) -3 Viewing angle contrast (contrast in diagonal direction)
Using a measuring instrument (BM5A, manufactured by TOPCON), the luminance values of black display and white display at an azimuth direction of 45 degrees and a polar angle direction of 60 degrees from the front of the apparatus are measured in a dark room, and a viewing angle contrast (white luminance) / Black luminance) was calculated and evaluated as follows.
○: Viewing angle contrast is 50 or more Δ: Viewing angle contrast is less than 50, 25 or more ×: Viewing angle contrast is less than 25 (unacceptable)

＊１は、フロント側偏光板の外側保護フィルム；＊２は、フロント側偏光板の内側保護フィルム；＊３は、リア側偏光板の内側保護フィルム；＊４は、フロント側偏光板の外側保護フィルムである。実施例では、リア側偏光板の内側保護フィルム（＊３）が、リア側位相差領域に相当し、フロント側偏光板の内側保護フィルム（＊２）が、フロント側位相差領域に相当する。

* 1 is an outer protective film for the front side polarizing plate; * 2 is an inner protective film for the front side polarizing plate; * 3 is an inner protective film for the rear side polarizing plate; * 4 is an outer protective film for the front side polarizing plate It is a film. In the examples, the inner protective film (* 3) of the rear-side polarizing plate corresponds to the rear-side retardation region, and the inner protective film (* 2) of the front-side polarizing plate corresponds to the front-side retardation region.

From the above results, all of the liquid crystal display devices of the embodiments of the present invention have a high front CR, the rear substrate is an array substrate, and a retardation film having an Rth (550) of about 100 nm as a rear inner protective film. It can be understood that the front contrast is improved as compared with the liquid crystal display device of the reference form (Comparative Examples 5, 15, 17 and 18) having
Specifically, in Examples 1 to 14, since the liquid crystal cell 2 in which the color filter and the TFT array are arranged on the front side substrate is used, Rth (550) of the rear side phase difference region is 105 nm. It can be understood that this is an improvement over the liquid crystal display device of Comparative Example 5 having the liquid crystal cell 4 in which the color filter is disposed on the front substrate and the TFT array is disposed on the rear substrate.
Further, the liquid crystal display devices of Examples 1 to 14 and 20 to 22 have the liquid crystal cell 2 in the same manner, but Rth (550) in the rear side retardation region is 100 nm, and does not reach 105 nm. Compared with the liquid crystal display device of Example 1, it can be understood that the front CR is improved.

Further, in the liquid crystal display devices of Examples 15 and 16 having the liquid crystal cell 1 using the COA substrate as the front side substrate, the Rth (550) in the rear side retardation region has the liquid crystal cell 1 in the same manner. It can be understood that the front CR is remarkably improved as compared with the liquid crystal display device of Comparative Example 15 which is 100 nm and does not reach 105 nm.
Similarly, in the liquid crystal display device of Example 18 having the liquid crystal cell 6 in which the color filter and the TFT array are arranged on the front side substrate, the Rth (550) of the rear side retardation region is 105 nm, and the front side substrate has color. It can be understood that the front CR is remarkably improved as compared with the liquid crystal display device of Comparative Example 17 having the filter and the liquid crystal cell 7 in which the TFT array is arranged on the rear substrate.
Similarly, in the liquid crystal display device of Example 19 employing the field sequential drive type liquid crystal cell 8 in which the TFT array is arranged on the front side substrate, the rear side retardation region Rth (550) is 105 nm, and the rear side It can be understood that the front CR is remarkably improved as compared with the liquid crystal display device of Comparative Example 18 employing the field sequential drive type liquid crystal cell 9 in which the TFT array is arranged on the substrate.

  It is understood that in the liquid crystal cell in which the color filter and the TFT array are arranged on the front side substrate, the bright room contrast is remarkably improved in the liquid crystal cell 2 having the light shielding portion compared to the liquid crystal cell 5 having no light shielding portion. it can.

Next, a propylene / ethylene random copolymer (Sumitomo Nobrene W151, manufactured by Sumitomo Chemical Co., Ltd.) containing about 5% by mass of ethylene units is transferred to a melt extrusion molding machine in which a T-die is arranged in a single-screw melting extruder. Extrusion is performed at a melting temperature of 230 ° C. to obtain a raw film, and then the original film is sequentially biaxially stretched in the order of longitudinal stretching at a stretching ratio of 2.5 times and transverse stretching at a stretching ratio of 3.5 times. The film was stretched to obtain a transparent film having Re (550) = 60 nm and Rth (550) = 250 nm. Furthermore, both the front and back surfaces of this transparent film were subjected to corona discharge treatment to produce a polypropylene polymer film 20.
In the liquid crystal display devices of Example 3 and Comparative Example 9, similar to Example 3 and Comparative Example 9 except that the film 9 used as the front side or rear side inner protective film (* 2) was replaced with the film 20. A liquid crystal display device having the structure described above was fabricated and evaluated in the same manner. Since these two liquid crystal display devices have the liquid crystal cell 2 having the array substrate as the front substrate, the liquid crystal display device having the film 20 having Rth (550) of 250 nm in the rear retardation region is a film. As compared with the liquid crystal display device having 20 in the front side retardation region, the front CR improvement effect was obtained. Even in the case of a polypropylene-based polymer film, the effect of the present invention can be obtained as long as the rear-side retardation region satisfies the formula (I).

  In the above embodiment, as the outer protective film on the front side and the rear side, the film 13 and the film 18, that is, the cellulose acylate film is used, but the front side and / or the rear side are used. As an outer protective film, for example, even a cellulose acylate film, other cellulose acylates (eg, films of cellulose propionate, cellulose butyrate, etc.), polyolefins (eg, norbornene polymers, polypropylene polymers), A similar effect may be obtained by using a film mainly composed of poly (meth) acrylic acid ester (eg, polymethyl methacrylate), polycarbonate, polyester, or polysulfone, and other commercially available polymer films (norbornene type) In polymer, art (Manufactured by JSR), would the same effect can be obtained by using ZEONOR (manufactured by Nippon Zeon), etc.).

Reference example:
In the liquid crystal display device of Example 3, a liquid crystal display device having the same configuration as that of Example 3 was prepared except that the film 9 used as the inner protective film (* 2) on the front side was replaced with the film 1. Evaluation was performed in the same manner. This liquid crystal display device has the liquid crystal cell 2 having the array substrate as the front substrate, and the rear side retardation region Rth (550) is 250 nm. Therefore, the front CR improvement effect equivalent to that of the third embodiment is obtained. Although obtained, the viewing angle CR was inferior to that of Example 3.

  According to the present invention, it is possible to provide a VA (Vertically Aligned) liquid crystal display device with improved front contrast.

DESCRIPTION OF SYMBOLS 10 Liquid crystal layer 12 Color filter layer 14 Array member 16 Rear side board | substrate 18 Front side board | substrate 20 Rear side phase difference area | region 22 Front side phase difference area | region 24 Rear side polarizer 26 Front side polarizer 28 VA type of backlight unit LC COA structure Liquid crystal cell PL1 Rear polarizing plate PL2 Front polarizing plate

Claims (16)

Front side polarizer, rear side polarizer, liquid crystal layer disposed between front side polarizer and rear side polarizer, and one or more layers disposed between rear side polarizer and liquid crystal layer Retardation layer (the whole of one or more retardation layers disposed between the rear-side polarizer and the liquid crystal layer is referred to as a “rear-side retardation region”), and the rear-side retardation The area is the following formula (I)
(I): 105 nm ≦ Rth (550)
(However, Rth (λ) means retardation in the thickness direction (nm) at a wavelength of λnm);
And a front-side substrate having a TFT array is disposed between the front-side polarizer and the liquid crystal layer. 2. The VA liquid crystal display device according to claim 1, further comprising a light shielding layer and / or an antireflection layer for suppressing reflection of the TFT array between the TFT array and the front polarizer. The VA liquid crystal display device according to claim 1, wherein the front substrate is a color filter on array substrate. The rear phase difference region is represented by the following formula (I ′)
(I ′): 105 nm ≦ Rth (550) ≦ 300 nm
The VA liquid crystal display device according to claim 1, wherein: The rear side phase difference region has the following formula (II)
(II): | Re (550) | ≦ 90 nm
Where Re (λ) means in-plane retardation (nm) at a wavelength λnm;
5. The VA liquid crystal display device according to claim 1, wherein: One layer or two or more retardation layers arranged between the front polarizer and the liquid crystal layer as a whole (hereinafter referred to as one layer arranged between the front polarizer and the liquid crystal layer or The entire retardation layer of two or more layers is referred to as “front side retardation region”), the following formula (III)
(III): | Rth (550) | ≦ 170 nm
The VA type liquid crystal display device according to claim 1, wherein the VA type liquid crystal display device is satisfied. The front side phase difference region is represented by the following formula (IV)
(IV): 30 nm ≦ Re (550) ≦ 90 nm
The VA liquid crystal display device according to claim 6, wherein: The VA liquid crystal display device according to claim 1, wherein the front polarizer is directly bonded to the VA liquid crystal cell. The said rear side phase difference area | region consists of one biaxial polymer film, or contains one biaxial polymer film, The any one of Claims 1-8 characterized by the above-mentioned. VA type liquid crystal display device. 10. The VA according to claim 1, wherein the rear side retardation region is made of one uniaxial polymer film or includes one uniaxial polymer film. 11. Type liquid crystal display device. The said front side phase difference area | region and / or a rear side phase difference area | region consists of a cellulose acylate type film, or contains a cellulose acylate type film, It is any one of Claims 1-10 characterized by the above-mentioned. VA type liquid crystal display device. The said front side phase difference area | region and / or a rear side phase difference area | region consists of a cyclic olefin type polymer film, or contains a cyclic olefin type polymer film, The one of Claims 1-11 characterized by the above-mentioned. VA type liquid crystal display device. The VA liquid crystal according to claim 1, wherein the front side retardation region and / or the rear side retardation region is made of an acrylic polymer film or includes an acrylic polymer film. Display device. The front side retardation region and / or the rear side retardation region contains an acrylic polymer containing at least one unit selected from a lactone ring unit, a maleic anhydride unit, a glutaric anhydride unit, and a glutarimide unit. The VA type liquid crystal display device according to claim 13, wherein the VA type liquid crystal display device comprises an acrylic polymer film or contains the acrylic polymer film. The VA liquid crystal display device according to claim 1, wherein the front-side retardation region and / or the rear-side retardation region is made of a polypropylene resin or contains a polypropylene resin. . The VA liquid crystal display device according to any one of claims 1 to 15, further comprising a backlight unit that sequentially emits independent three primary color lights, and is driven by a field sequential driving method.

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