JP2002196142A - Polarizing element, polarizing plate and liquid crystal display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a polarization element which can be made flat and thin using a simple structure and which can improve the reflection luminance of a reflection-type liquid crystal display and make the liquid crystal display bright. SOLUTION: In the polarization element, which scatters one of linearly polarized light components perpendicular to each other and substantially transmits the other, the optical anisotropic phase is aligned obliquely and uniaxially, while the azimuth from the transmission axis is kept perpendicular to the transmission axis, so as to change the polarization state of the scattered light.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a polarizing element having an anisotropic scattering layer which scatters one of orthogonal linearly polarized light and substantially transmits the other. Further, the present invention relates to a polarizing plate in which a light absorbing polarizing element and a light scattering polarizing element are laminated. Further, the present invention relates to a liquid crystal display device having improved light use efficiency.

[0002]

2. Description of the Related Art When natural light such as sunlight or light from a light source such as a lamp is transmitted through a polarizing element, light in various polarization states such as linearly polarized light, circularly polarized light, and elliptically polarized light can be generated. Polarizing elements are widely used as important members of main liquid crystal display devices such as electric field control birefringence mode and twisted nematic (TN) mode (Susumu Sato, “Liquid Crystal and its Applications,” Sangyo Tosho, 96 ~ 11
On page 5).

As a polarizing element used in a liquid crystal display device, generally, an iodine-based or dye-based dichroic light-absorbing polarizing element is widely used. The light-absorbing polarizing element generates linearly polarized light by absorbing only one of the orthogonal polarization components and not transmitting the other, thereby transmitting the other orthogonal polarization component. However, since linearly polarized light is generated by light absorption, when the degree of polarization is close to 100%, the upper limit of the light transmittance is 50% in principle. Therefore, an actual liquid crystal display has a problem that only half or less light can be used, and the display luminance is low. Conventionally, several means for performing polarization conversion have been proposed in order to improve the light use efficiency of a light source (described in JP-A-63-121821, JP-A-5-224175, and JP-A-5-232433). ). The anisotropic reflection type and the anisotropic scattering type have been industrialized as brightness enhancement films and are widely used in transmission type liquid crystal displays.

In the anisotropic reflection system, a uniaxially stretched film and a non-stretched film are laminated in multiple layers, and the refractive index difference in the stretching direction is increased to increase the refractive index in the stretching direction. This element and a normal dichroic light-absorbing polarizing element are stacked and used as a polarizing element on the backlight side. From this, the light use efficiency of the backlight can be increased (WO95 / 17691, WO9
5/17692 and WO95 / 17699). Specifically, there are a multilayer film system and a cholesteric liquid crystal system. The multilayer film method has a large frontal luminance improving effect, but requires a number of stacked layers of several tens or more in order to increase the degree of polarization, and thus has a problem in productivity. The cholesteric liquid crystal system can be easily implemented by stacking cholesteric liquid crystals having different pitch lengths in a vertically aligned state and combining them with a λ / 4 plate (described in European Patent No. 606940A2 and Japanese Patent Application Laid-Open No. Hei 8-271731). The cholesteric liquid crystal system has a lower front luminance than the multilayer film system.

The anisotropic scattering method utilizes the property that a film obtained by stretching a composite of a polymer and a liquid crystal becomes an optically anisotropic scatterer (anisotropic scatterer) (Liquid Crystals, 1993). Year, Vol. 15, No. 3, pp. 395-407). WO97 / 32223, WO97 / 322
No. 24, WO97 / 32225, WO97 / 3222
6 and JP-A-9-274108, 1
Each publication of 1-174231 proposes a method of producing an anisotropic scatterer by blending a positive intrinsic birefringent polymer and a negative intrinsic birefringent polymer and uniaxially stretching. The anisotropic scattering method has a feature that the viewing angle dependence of luminance is small, but the degree of improvement in front luminance is smaller than that of the anisotropic reflection method.

[0006] By the way, the reflection type liquid crystal display device is used as a display of a portable device such as a portable information terminal, a portable game machine or a portable telephone because a backlight is not required and the power consumption is small. It is expected that the market will expand rapidly. The reflection type liquid crystal display device has a basic structure in which a reflection plate, a liquid crystal cell, and a polarizing film are laminated in this order. Regarding the display mode of the liquid crystal cell, TN (Twisted Nematic) and STN (Supper Twis
ted Nematic), HAN (Hybrid Aligned Nematic),
HPDLC (Holographic Polymer Dispersed Liquid C
Various display modes such as rystal) have been proposed.
TN mode and STN mode reflective liquid crystal display devices have already been put to practical use and widely used.

The anisotropic reflection type and anisotropic scattering type brightness enhancement films can reuse light reflected or backscattered to the backlight side and reflected at the backlight portion in a transmission type liquid crystal display device. However, in the reflection type liquid crystal display device, most of the reflected or backscattered light is emitted to the atmosphere, and cannot be reused in the above-mentioned brightness enhancement film. Therefore, at present, the reflection type liquid crystal display device does not have an effective degree of luminance improvement.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a polarizing element which is effective for a reflection type liquid crystal display. Another object of the present invention is to provide a polarizing plate capable of improving the brightness of a liquid crystal display device, particularly, a reflective liquid crystal display device. Still another object of the present invention is to provide a liquid crystal display device having improved light use efficiency.

[0009]

The object of the present invention is to provide the following polarizing elements (1) to (14) and the following polarizing elements (15) to (20).
And the liquid crystal display of the following (21) to (25). (1) A polarizing element having an anisotropic scattering layer that scatters one of orthogonal linearly polarized light and substantially transmits the other, and at least 50% of incident light having a plane of polarization parallel to the scattering axis.
Is emitted to the opposite side of the incident surface, and at least 10% of the emitted scattered light is converted into elliptically polarized light or linearly polarized light having an azimuth angle of 20 degrees or more with respect to the scattering axis.

(2) The anisotropic scattering layer is composed of an optically isotropic continuous phase and an optically anisotropic discontinuous phase, and the slow axis of the optically anisotropic discontinuous phase corresponds to the transmission axis. The polarizing element according to (1), wherein the polarizing element is tilted to the incident side or the outgoing side by 10 degrees or more with respect to the scattering axis while maintaining the azimuth perpendicular. (3) The anisotropic scattering layer is composed of an optically anisotropic continuous phase and an optically isotropic discontinuous phase, and the slow axis of the optically anisotropic continuous phase has the azimuth perpendicular to the transmission axis. 1 for the scattering axis while maintaining
The polarizing element according to (1), which is inclined to the incident side or the outgoing side by 0 degree or more.

(4) The difference in refractive index in the transmission axis direction between the optically isotropic continuous phase and the optically anisotropic discontinuous phase in the in-plane direction of the film is less than 0.05. Polarizing element. (5) The polarizing element according to (2), wherein the difference in the refractive index in the scattering axis direction between the optically isotropic continuous phase and the optically anisotropic discontinuous phase is 0.03 or more in the in-plane direction of the film. . (6) The polarizing element according to (3), wherein the difference in the refractive index in the transmission axis direction between the optically anisotropic continuous phase and the optically isotropic discontinuous phase in the in-plane direction is less than 0.05. . (7) The polarizing element according to (3), wherein the difference in the refractive index in the scattering axis direction between the optically anisotropic continuous phase and the optically isotropic discontinuous phase is 0.03 or more in the in-plane direction of the film. .

(8) The polarizing element according to (2), wherein the optically isotropic continuous phase comprises a polymer compound. (9) The polarizing element according to (2), wherein the optically anisotropic discontinuous phase has an average diameter of an approximate circle of 0.01 to 10 μm. (10) The polarizing element according to (3), wherein the optically isotropic discontinuous phase has an average diameter of an approximate circle of 0.01 to 10 μm.

(11) The polarizing element according to (2), wherein the optically anisotropic discontinuous phase contains a liquid crystalline compound. (12) The polarizing element according to (3), wherein the optically anisotropic continuous phase contains a liquid crystalline compound. (13) The polarizing element according to (11) or (12), wherein the liquid crystal compound has a polymerizable group. (14) The polarizing element according to (11) or (12), wherein the liquid crystal compound has a smectic C phase.

(15) A light-absorbing polarizing element having an anisotropic scattering layer that absorbs one of orthogonal linearly polarized light and substantially transmits the other, and scatters one of orthogonal linearly polarized light and substantially converts the other. A light-scattering polarizing element having an anisotropic scattering layer that transmits light is disposed such that the polarization transmission axis of the light-absorbing polarization element and the polarization transmission axis of the light-scattering polarization selection element are substantially parallel to each other. Wherein at least 50% of incident light having a plane of polarization parallel to the scattering axis of the light-scattering polarization selection element exits on the opposite side of the plane of incidence, and at least 10% of the emitted scattered light comprises A polarizing plate characterized by being converted into elliptically polarized light or linearly polarized light having an azimuth with respect to a scattering axis of 20 degrees or more.

(16) The degree of polarization of the light absorbing polarizing element is 99.
% Or more. (17) Having at least one transparent support (15)
The polarizing plate according to 1. (18) The polarizing plate according to (17), wherein the transparent support comprises a cellulose triacetate film. (19) The polarizing plate according to (18), wherein the transparent support is a cellulose triacetate film produced without using methylene chloride. (20) An optically anisotropic layer formed from discotic liquid crystal molecules is further provided, and the optically anisotropic layer, the light-absorbing polarizing element, and the light-scattering polarizing element are stacked in this order (15). The polarizing plate according to (1).

(21) A reflection type liquid crystal display device in which a reflection plate, a liquid crystal cell, a λ / 4 plate and a polarizing plate are laminated in this order, wherein the polarizing plate is one of a transparent support and orthogonal linearly polarized light. A light-absorbing polarizing element having an anisotropic scattering layer that absorbs and substantially transmits the other, and a light-scattering type that has an anisotropic scattering layer that scatters one of orthogonal linearly polarized light and substantially transmits the other. It is composed of a laminate of polarizing elements, and is disposed so that the polarization transmission axis of the light-absorbing polarization element and the polarization transmission axis of the light-scattering polarization selection element are substantially parallel to each other. At least 50% of incident light having a plane of polarization parallel to the scattering axis exits on the opposite side of the plane of incidence, and at least 10% of the emitted scattered light has elliptically polarized light or linearly polarized light having an azimuth angle of 20 degrees or more with the scattering axis. Reflective liquid characterized by being converted to Display device.

(22) A reflection type liquid crystal display device in which a reflection plate, a liquid crystal cell and a polarizing plate are laminated in this order,
A polarizing plate, which absorbs one of the λ / 4 plate and orthogonal linearly polarized light and scatters one of the orthogonal linearly polarized light and a light-absorbing polarizing element having an anisotropic scattering layer that substantially transmits the other,
It consists of a laminate of a light-scattering polarizing element having an anisotropic scattering layer that substantially transmits the other, and the polarization transmission axis of the light-absorbing polarizing element and the polarization transmission axis of the light-scattering polarization selection element are substantially equal. At least 50% of the incident light having a polarization plane parallel to the scattering axis of the light-scattering polarization selection element is arranged so as to be parallel, and exits to the opposite side of the entrance plane, and at least 10% of the emitted scattered light. Is converted into elliptically polarized light or linearly polarized light having an azimuth angle of 20 degrees or more with respect to a scattering axis.

(23) A liquid crystal display device in which a backlight, a polarizing plate, a liquid crystal cell of a twisted nematic alignment mode, and a polarizing film are stacked in this order, wherein the polarizing plate on the backlight side is arranged from the liquid crystal cell side. In order, absorbs one of the optically anisotropic layer formed from discotic liquid crystalline molecules, the optically anisotropic transparent support, and the orthogonal linearly polarized light,
A light-absorbing polarizing element having an anisotropic scattering layer that substantially transmits the other, and scatters one of orthogonal linearly polarized light,
An average of the orthogonal projection of the normal of the discotic liquid crystalline molecule onto the optically anisotropic transparent support, which is composed of a laminate of light scattering type polarizing elements having an anisotropic scattering layer substantially transmitting the other. The angle between the direction and the in-plane slow axis of the optically anisotropic transparent support is substantially parallel or perpendicular, and the in-plane slow axis of the optically anisotropic transparent support and the polarization transmission of the light-absorbing polarizing element. The axes are substantially parallel or perpendicular to each other, and the polarization transmission axis of the light-absorbing polarization element and the polarization transmission axis of the light-scattering polarization element are arranged to be substantially parallel. At least 50% of the incident light having a plane of polarization parallel to the scattering axis of the selection element is emitted to the opposite side of the plane of incidence, and at least 10% of the emitted scattered light is elliptically polarized light having an azimuth of 20 degrees or more with respect to the scattering axis. Or a twisted nematic, characterized by being converted to linearly polarized light. The liquid crystal display device of the alignment mode.

(24) In a liquid crystal display device in which a backlight, a polarizing plate, a liquid crystal cell in a bend alignment mode, and a polarizing plate are laminated in this order, the polarizing plate on the backlight side is arranged in order from the liquid crystal cell side. , An optically anisotropic layer formed from discotic liquid crystal molecules, an optically anisotropic transparent support,
A light-absorbing polarizing element having an anisotropic scattering layer that absorbs one of orthogonal linearly polarized light and substantially transmits the other, and
It consists of a stack of light-scattering polarizing elements having an anisotropic scattering layer that scatters one of the orthogonal linearly polarized light and substantially transmits the other, and the optical anisotropy of the normal to the discotic liquid crystal molecule disk surface. The angle between the average direction of orthogonal projection to the transparent support and the in-plane slow axis of the optically anisotropic transparent support is substantially 45 degrees, and the in-plane slow axis of the optically anisotropic transparent support is And the polarization transmission axis of the light absorption type polarization element is substantially parallel or perpendicular, and the polarization transmission axis of the light absorption type polarization element and the polarization transmission axis of the light scattering type polarization element are substantially parallel. And at least 50% of the incident light having a polarization plane parallel to the scattering axis of the light-scattering type polarization selection element is emitted to the opposite side of the incident plane, and at least 10% of the emitted scattered light is at The azimuth angle is converted to elliptically polarized light or linearly polarized light of 20 degrees or more. The liquid crystal display device of bend alignment mode to.

(25) In a liquid crystal display device in which a backlight, a polarizing plate, a liquid crystal cell in a horizontal alignment mode, and a polarizing plate are laminated in this order, the polarizing plate on the backlight side is arranged in order from the liquid crystal cell side. , An optically anisotropic layer formed from discotic liquid crystal molecules, an optically anisotropic transparent support,
A light-absorbing polarizing element having an anisotropic scattering layer that absorbs one of orthogonal linearly polarized light and substantially transmits the other, and
It consists of a stack of light-scattering polarizing elements having an anisotropic scattering layer that scatters one of the orthogonal linearly polarized light and substantially transmits the other, and the optical anisotropy of the normal to the discotic liquid crystal molecule disk surface. The angle between the average direction of orthogonal projection to the transparent support and the in-plane slow axis of the optically anisotropic transparent support is substantially 45 degrees, and the in-plane slow axis of the optically anisotropic transparent support is And the polarization transmission axis of the light absorption type polarization element is substantially parallel or perpendicular, and the polarization transmission axis of the light absorption type polarization element and the polarization transmission axis of the light scattering type polarization element are substantially parallel. And at least 50% of the incident light having a polarization plane parallel to the scattering axis of the light-scattering type polarization selection element is emitted to the opposite side of the incident plane, and at least 10% of the emitted scattered light is at The azimuth angle is converted to elliptically polarized light or linearly polarized light of 20 degrees or more. The liquid crystal display device of the horizontal alignment mode to.

[0021]

FIG. 1 is a schematic diagram showing a basic structure of an anisotropic scattering layer. In the anisotropic scattering layer shown in FIG. 1, the optically anisotropic discontinuous phase (1) exists in the optically isotropic continuous phase (2) in a dispersed state with phase separation. The discontinuous phase (1) is made of an optically anisotropic compound having birefringence, and the slow axis (6) corresponding to the major axis direction of the molecule is maintained while maintaining the azimuth angle to the transmission axis (4) perpendicularly. It is inclined by a fixed angle (θ) with respect to the scattering axis (3). The light incident direction (5) is set in a direction perpendicular to both the transmission axis (4) and the scattering axis (3).

FIG. 2 is a schematic diagram showing another basic configuration of the anisotropic scattering layer. In the anisotropic scattering layer shown in FIG. 2, an optically isotropic discontinuous phase (8) is contained in an optically anisotropic continuous phase (7).
Exist in a dispersed state after phase separation. The continuous phase (7) is made of an optically anisotropic compound having birefringence, and has a transmission axis (1).
While keeping the azimuth with (0) perpendicular, the slow axis (12) corresponding to the major axis direction of the molecule is inclined by a certain angle (θ) with respect to the scattering axis (9). The light incident direction (11) is set in a direction perpendicular to both the transmission axis (10) and the scattering axis (9).

FIG. 3 is a schematic sectional view showing a general form of the polarizing element. The polarizing element shown in FIG. 3 includes only the anisotropic scattering layer (13) shown in FIG. 1 or FIG. FIG.
FIG. 3 is a schematic cross-sectional view showing another general form of the polarizing element. The polarizing element shown in FIG. 4 has an anisotropic scattering layer (13) provided on a transparent support (14). FIG. 5 is a schematic sectional view showing another general form of the polarizing element. The polarizing element shown in FIG. 5 has a configuration in which the anisotropic scattering layer (13) is sandwiched between two transparent supports (14).

FIG. 6 is a schematic sectional view showing a polarizing plate in which a light scattering type polarizing element and a light absorbing type polarizing element are combined.
In the polarizing plate shown in FIG. 6, a light-absorbing polarizing element in which a light-absorbing polarizing layer (16) is sandwiched between two transparent supports (14) and a light-scattering polarizing element (15) are separated. use. FIG. 7 is a schematic cross-sectional view showing another polarizing plate in which a light-scattering polarizing element and a light-absorbing polarizing element are combined.
In the polarizing plate shown in FIG. 7, a light scattering type polarizing element (15) is
Used as one protective film of the light-absorbing polarizing layer (16). The other protective film is a transparent support (14). FIG. 8 is a schematic cross-sectional view showing another polarizing plate in which a light-scattering polarizing element and a light-absorbing polarizing element are combined. The polarizing plate shown in FIG.
Is used as one protective film of the light-absorbing polarizing layer (16). The other protective film functions as an optical compensation sheet (17). FIG. 9 is a schematic cross-sectional view showing still another polarizing plate in which a light-scattering polarizing element and a light-absorbing polarizing element are combined. Also in the polarizing plate shown in FIG. 9, the light-scattering polarizing element (15) is used as one protective film of the light-absorbing polarizing layer (16). The other protective film functions as λ / 4 (18).

FIG. 10 is a schematic sectional view of a reflection type liquid crystal display device including a polarizing plate. The reflective liquid crystal display device shown in FIG. 10 has a semi-transmissive film (22), a polarizing plate (21), and a light guide plate (23) horizontally provided with an LED (24) as a light source.
Twisted nematic (TN) mode liquid crystal cell (2
0) and a polarizing plate (19) arranged in this order. In the reflection type simple matrix-twisted nematic mode liquid crystal display device shown in FIG. 10, the polarizing plate according to the present invention can be used as the polarizing plate (19). FIG. 11 is a schematic cross-sectional view of another reflective liquid crystal display device including a polarizing plate. The reflective liquid crystal display device shown in FIG. 11 has a semi-transmissive film (22), a polarizing plate (21), and a light guide plate (23) horizontally provided with an LED (24) as a light source.
It has a structure in which a super twisted nematic (STN) mode liquid crystal cell (26), two retardation plates (25), and a polarizing plate (19) are arranged in this order. In the reflection type simple matrix-super twisted nematic mode liquid crystal display device shown in FIG. 11, the polarizing plate according to the present invention can be used as the polarizing plate (19).

FIG. 12 is a schematic sectional view of another reflection type liquid crystal display device including a polarizing plate. The reflection type liquid crystal display device shown in FIG. 12 includes a reflection plate (27), a liquid crystal cell (26) of a super twisted nematic (STN) mode, two retardation plates (25), and a polarizing plate (19). It has a structure arranged in order. In the reflection type simple matrix-super twisted nematic mode liquid crystal display device of the single-polarization film type shown in FIG.
As 9), the polarizing plate according to the present invention can be used. FIG. 13 is a schematic cross-sectional view of yet another reflective liquid crystal display device including a polarizing plate. The reflection type liquid crystal display device shown in FIG. 13 includes a reflection plate (27), a twisted nematic (T
An N) mode liquid crystal cell (20), a λ / 4 plate (29), a polarizing plate (19), and a light guide plate (23) are arranged in this order, and a cold cathode tube (28) is provided beside the light guide plate (23). ) As a light source. In the reflection type active matrix-twisted nematic mode liquid crystal display device shown in FIG. 13, the polarizing plate according to the present invention can be used as the polarizing plate (19). FIG. 14 is a schematic sectional view of still another reflection type liquid crystal display device including a polarizing plate.
The reflection type liquid crystal display device shown in FIG.
(23), a λ / 4 plate (29), two optical compensation films (31), a twisted nematic (T
An N) mode liquid crystal cell (30), a λ / 4 plate (29), and a polarizing plate (19) are arranged in this order. In the transflective active matrix-twisted nematic mode liquid crystal display device shown in FIG. 14, the polarizing plate according to the present invention can be used as the polarizing plate (19).

[Anisotropic scattering layer comprising an optically isotropic continuous phase and an optically anisotropic discontinuous phase] The optically isotropic continuous phase is
It is preferable to form from a material having a light transmittance of 80% or more. As the transparent support, a polymer film can be used. Examples of the polymer include polyolefin (eg, polyethylene), norbornene resin, polyethylene terephthalate, polyethylene naphthalate, polypropylene, polycarbonate, polystyrene, polyarylate, polysulfone, polyether sulfone, polyvinyl chloride, polyvinyl alcohol, and cellulose ester (eg, , Cellulose acetate). A film in which two or more kinds of polymers are mixed may be used. Commercially available polymers (eg, ZEONEX, ZEONOR, manufactured by Nippon Zeon Co., Ltd .; ARTON, manufactured by Nippon Synthetic Rubber Co., Ltd.) and FUJITAC (manufactured by Fuji Photo Film Co., Ltd.) can also be used. (Fuji Photo Film Co., Ltd.), polycarbonate, and Zeonor (Nippon Zeon Co., Ltd.) are particularly preferred.

The birefringence of the optically isotropic continuous phase is preferably less than 0.05, more preferably less than 0.03. The thickness of the anisotropic scattering layer is 0.5 to 50.
0 μm is preferable, and 1 to 100 μm is more preferable.

Optically anisotropic discontinuous phase (optically anisotropic dispersion
Phase) is composed mainly of a refractive index anisotropic material.
Preferably, stretching, light irradiation, electric field application, and magnetic field application are small.
Use at least one means to tilt the refractive index anisotropic material.
It is preferable to be derived from the state of being axially oriented. refraction
Index anisotropic material has a refractive index for one of linearly polarized light and
A material that has a different refractive index for the other polarization
And a liquid crystalline compound is preferred. Liquid crystalline compound
As an object, the ordinary refractive index (n_o) And extraordinary refractive index
(N_e), A liquid with a large intrinsic birefringence
Crystalline compounds are preferred. Preferred intrinsic birefringence is 0.05
And more preferably 0.08. The liquid crystal property
Compound n ₀And polymer elements constituting an optically isotropic continuous phase
The difference from the refractive index of the material is preferably less than 0.05
And more preferably less than 0.03. Also,
N of the liquid crystal compound_eAnd an optically isotropic continuous phase
The difference from the refractive index of the polymer material must be 0.03 or more
Preferably, it is more preferably 0.05 or more.

The liquid crystal compound is a low-molecular liquid crystal exhibiting a nematic phase or a smectic phase at room temperature or when heated, for example, a cyanobiphenyl liquid crystal, a cyanophenylcyclohexane liquid crystal, a cyanophenyl ester liquid crystal, a phenyl benzoate liquid crystal. Phenylpyrimidine-based liquid crystal, or a mixture thereof. Alternatively, a polymer liquid crystal exhibiting a nematic phase or a smectic phase at room temperature or in a heated state can be used.

For the optically anisotropic phase, a rod-like liquid crystalline compound can be preferably used. The rod-like liquid crystal compound and the composition thereof are described in Quarterly Review of Chemistry, Vol. 22, Liquid Crystal Chemistry (1994), Chapters 4 and 7 of the Chemical Society of Japan.
The compounds and compositions described in Chapter 3, Chapter 10, and Liquid Crystal Device Handbook, Chapter 3 of the 142nd Committee of the Japan Society for the Promotion of Science can be referred to. As the optically anisotropic phase, a rod-like liquid crystalline compound exhibiting a nematic phase and a smectic C phase can be preferably used.

In many cases, it is difficult to maintain the alignment state of the liquid crystal compound stably for a long period of time or for temperature, humidity or mechanical deformation. In order to maintain the alignment state over a long period of time, it is desirable to use a polymerizable liquid crystal compound and polymerize in the alignment state to form a crosslinked network structure. As a means for polymerizing the polymerizable liquid crystal compound, any of thermal polymerization and photopolymerization can be used. In the present invention, photopolymerization using ultraviolet rays is preferably used. The polymerizable group is preferably an ethylenically unsaturated group, and it is preferable that at least one polymerizable group is introduced per liquid crystal compound. From the viewpoint of heat resistance and uniformity of alignment, a bifunctional polymerizable liquid crystal compound having a photopolymerizable group at both ends of a rod-like liquid crystal molecule is particularly preferably used. Examples of the liquid crystalline compound preferably used for the optically anisotropic phase are shown below.

[0033]

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[0034]

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[0035]

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[0036]

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[0038]

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[0039]

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[0040]

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[0041]

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[0042]

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[0043]

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[0044]

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[0045]

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[0046]

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The preferred amount of the liquid crystal compound is 0.0 to 1 g of the polymer material constituting the optically isotropic continuous phase.
It is preferably from 01 to 2.0 g. More preferred is 0.01 to 1.5 g.

The liquid crystalline compound constituting the optically anisotropic discontinuous phase is preferably subjected to radical polymerization using light.
Examples of the photopolymerization initiator used for radical polymerization include thioxanthone-based photopolymerization initiators (eg, 2,4-diethylthioxanthone, 2-chlorothioxanthone), benzophenone-based photopolymerization initiators (eg, benzophenone, (4- (Methylphenylthio) phenyl) phenylmethanone) and an anthraquinone-based photopolymerization initiator (eg, ethylanthraquinone). Commercially available photopolymerization initiators (for example, Ciba
Irgacure184, Irgacu manufactured by Specialty Chemicals. Inc.
re369, Irgacure500, Irgacure651, Irgacure784, Ir
gacure819, Irgacure907, Irgacure1000, Irgacure130
0, Irgacure1700, Irgacure1800, Irgacure1850, Irg
acure2959, Darocur 1173, Darocur 4265, etc.). The addition amount of the photopolymerization initiator is preferably from 0.01% by mass to 20% by mass, and more preferably from 0.5% by mass to 10% by mass, based on the total amount of the polymerizable liquid crystal compound. preferable.

A photopolymerizable initiator may be used in combination with a spectral sensitizer or a photopolymerization accelerator (eg, isoamyl p-dimethylaminobenzoate, ethyl p-dimethylaminobenzoate). When a spectral sensitizer or a photopolymerization accelerator is added, a preferable addition amount is 10% by mass or more and less than 300% by mass of the photopolymerization initiator, and more preferably 20% by mass or more and less than 200% by mass.

An anisotropic scattering layer comprising an optically isotropic continuous phase and an optically anisotropic discontinuous phase is formed by adding a liquid crystalline compound to a solution of a polymer material constituting the polymer optically isotropic continuous phase. In addition, it is preferable to apply a liquid in which an additive such as a photopolymerizable initiator is dispersed, apply the liquid, dry the liquid, further align the liquid, and fix the alignment by light irradiation.

When the liquid crystal compound is emulsified and dispersed in an aqueous solution of polyvinyl alcohol or the like, it is preferable to add a surfactant to control the dispersion particle size or to impart dispersion stability. The surfactant to be added is not particularly limited, and any of nonionic and ionic (anion, cation, betaine) can be used.

The nonionic surfactant is a surfactant having a nonionic hydrophilic group of polyoxyethylene, polyoxypropylene, polyoxybutylene, polyglycidyl or sorbitan, and specifically, polyoxyethylene alkyl ether, Polyoxyethylene alkyl phenyl ether, polyoxyethylene-polyoxypropylene glycol, polyhydric alcohol fatty acid partial ester, polyoxyethylene polyhydric alcohol fatty acid partial ester, polyoxyethylene fatty acid ester, polyglycerin fatty acid ester, fatty acid diethanolamide, triethanol Amine fatty acid partial esters may be mentioned. As the anionic surfactant, carboxylate, sulfate, sulfonate, phosphate ester salt can be used. Representative anionic surfactants include fatty acid salts, alkyl benzene sulfonates, alkyl naphthalene sulfonates,
Alkyl sulfonate, α-olefin sulfonate, dialkyl sulfosuccinate, α-sulfonated fatty acid salt, N-methyl-N-oleyltaurine, petroleum sulfonate, alkyl sulfate, sulfated oil, polyoxyethylene alkyl Ether sulfate, polyoxyethylene alkyl phenyl ether sulfate, polyoxyethylene styrenated phenyl ether sulfate, alkyl phosphate, polyoxyethylene alkyl ether phosphate and naphthalene sulfonate formaldehyde condensate.

As the cationic surfactant, amine salts, 4
Secondary ammonium salts and pyridinium salts can be used. First
Salts of tertiary to tertiary aliphatic amines and quaternary ammonium salts (eg, tetraalkylammonium salts, trialkylbenzylammonium salts, alkylpyridium salts, alkylimidazolium salts) are preferred. Carboxybetaine and sulfobetaine are preferred as amphoteric surfactants. Examples of amphoteric surfactants include N-trialkyl-
N-carboxymethyl ammonium betaine and N-
And trialkyl-N-sulfoalkylene ammonium betaines.

Regarding surfactants, various references (for example, applications of surfactants, written by Koshobo and Takao Karimei, Showa 55)
Issued September 1, 2002). The amount of the surfactant used is preferably 0.001 to 1 g per 1 g of the discontinuous phase liquid crystal compound. 0.01 to 0.1 g is more preferable. For the dispersion, a method using a stirrer such as an ultrasonic dispersion method and a homogenizer, and a method using a kneader such as a sand mill and a colloid mill are preferable. When dispersing a liquid crystal compound in a water-insoluble polymer (eg, cellulose acetate), a uniform transparent mixed solution is prepared by mixing an organic solvent solution of a liquid crystal compound with an organic solvent solution of a water-insoluble polymer, and then a drying step after coating. Is preferably carried out to perform phase separation.

The size of the discontinuous phase is 0.01 to 10 μm as an average diameter of an approximate circle in which each region is approximated by a circle having substantially the same area.
Is preferably in the range of 0.05 to 5 μm
Is preferably within the range.

The coating method includes dip coating, air knife coating, curtain coating, roller coating,
Wire bar coating method, gravure coating method or extrusion coating method (US Pat. No. 2,681,294)
Are preferably used. Two or more layers may be applied simultaneously. The method of simultaneous coating is described in U.S. Pat.
No. 2941898, No. 3508947, No. 3526
No. 528, and Yuji Harazaki, Coating Engineering, page 253, Asakura Shoten (1973).

The preferred thickness of the anisotropic scattering layer is 0.5 to 100 μm, more preferably 1 to 70 μm.

[Means for tilting uniaxial orientation] The liquid crystalline compound constituting the optically anisotropic discontinuous phase can be tilted uniaxially oriented using at least one of stretching, light irradiation, electric field application, and magnetic field application. preferable.

(1) Stretching method When the liquid crystal compound is tilted uniaxially oriented by the stretching method, the liquid crystal compound is spontaneously tilted and smectic-aligned.
It is preferred to use compounds having a C phase. The anisotropic scattering layer composed of the optically isotropic continuous phase and the optically anisotropic discontinuous phase is applied to an endless support such as a band or a drum, or a transparent support by the above method, and then peeled off. After stretching, it may be laminated on a transparent support, or coated on a transparent support, and then used as it is, stretched or laminated with another transparent support or transferred to another transparent support, and formed. You may. When the discontinuous phase is a liquid crystalline compound, a high draw ratio of 4 to 10 times is not necessary as in the case of an iodine absorption type polarizing film. Therefore, the draw ratio is preferably 3.0 times or less from the viewpoint of productivity. .0
It is more preferably twice or less.

(2) Photo-Alignment Method When the liquid crystal compound is tilted uniaxially aligned by light irradiation, it is preferable to add a compound containing a photochemically reactive group to the liquid crystal compound and / or the optically isotropic binder. . The photochemically reactive group means a functional group that undergoes photodecomposition, photocrosslinking, photopolymerization, photooxidation and reduction, phototransition, and photoisomerization via a state excited by absorbing light energy. A functional group that performs crosslinking and / or photoisomerization can be particularly preferably used. The photocrosslinkable functional group breaks bonds in the molecule by light irradiation, or bonds active molecules such as radicals generated by cleavage of a part of the bond (photodimerization), or forms other molecules. It is a functional group that undergoes a binding reaction as radicalization. Such a photocrosslinkable functional group includes, for example, a cinnamoyl group, a cinnamylidene group, a diazo group, an azide group,
Examples thereof include an acryloyl group, a chalcone group, and a coumarin group. Among them, in the present invention, a photodimerizable functional group such as a cinnamoyl group, a cinnamylidene group, a chalcone group, and a coumarin group is particularly preferable.

Examples of the functional group that performs the photoisomerization reaction include an azobenzene group that undergoes cis-trans isomerization by light irradiation (K. Ichimura et al, Langmuir. Vol. 4, 2); K. Ichimur
a et al, Appl.Phys.Lett.Vol.63, No.4, Page449 (1993)
; N.Ishizuki, Langmuir.Vol.9, Page3298 (1993); N.Is
hizuki, Langmuir. Vol. 9, Page 857 (1993)), hydrazono
β-ketoester group (S. Yamamura et al, Liquid Crysta
13, Vol. 13, No. 2, page 189 (1993)), stilbene group (Kunihiro Ichimura et al., Journal of Polymers, Vol. 47, No. 10, page 771 (1990)), and spiropyran group (K. Ichimura et al, Chemistry Letters, P
age1063 (1992); K. Ichimura et al, Thin Solid Films,
Vol.235, Page 101 (1993)). An azobenzene group and a stilbene group can be preferably used.

The preferred amount of the photochemically reactive compound used is
0.001 to 1 per 1 g of the liquid crystal compound in the discontinuous phase
g is preferred. 0.01 to 0.1 g is more preferable. Preferred examples of the photochemically reactive compound are shown below.

[0063]

Embedded image

The photo-alignment is preferably performed by irradiation with linearly polarized light or irradiation with obliquely non-polarized light. As the wavelength of the irradiation light, a wavelength region in which the photochemically reactive compound used has optical absorption can be preferably used. 190nm or more, 500n
m, more preferably less than 250
nm or more and less than 450 nm. Light sources are ultra-high pressure mercury lamp, flash mercury lamp, high pressure mercury lamp, low pressure mercury lamp, low pressure mercury lamp, deep UV lamp,
Xenon lamps, xenon flash lamps, and metal halide lamps can be preferably used. When photo-alignment is performed using linearly polarized light, it is preferable that ultraviolet light emitted from the light source pass through a polarizing element to be linearly polarized. The polarizing element is preferably a prism element such as a Glan-Taylor prism or a Glan-Thompson prism, or a reflective polarizing element utilizing a Brewster angle. The irradiation light amount is preferably 1 to 2000 mJ / cm ² , more preferably 5 to 1000 mJ / cm ^2.
/ Cm ² . In order to develop optical anisotropy in a short time, irradiation with linearly polarized light while heating is also preferably performed in the present invention. The preferred temperature range of the substrate during irradiation with linearly polarized light is 0 ° C or more and less than 200 ° C, and more preferably 10 ° C or more and less than 150 ° C. In addition, when photo-alignment is performed using oblique non-polarized light, Polym. Mater. Sci. En
g., 66, p263 (1992).

(3) Electric Field Orientation Method A liquid crystal compound dispersed in an optically isotropic continuous phase is inserted between the inclined electrodes of a film, and a voltage of 1 V or more and less than 2000 V is applied to the liquid crystal of the discontinuous phase. The compound can be tilted uniaxially oriented. The inclination angle of the electrode is 10 degrees or more and 8
Less than 0 degrees is preferred. Further, it is preferable to apply a voltage in a temperature range in which the liquid crystal compound forms a liquid crystal phase, and to irradiate ultraviolet rays in the alignment state to fix the inclined alignment state.

(4) Magnetic Field Orientation Method A magnetic field of 0.2 T or more and less than 10 T is inserted between magnetic poles of a magnetic field alignment device provided with a tilted electromagnetic coil of a film in which a liquid crystalline compound is dispersed in an optically isotropic continuous phase. Is applied, the liquid crystal compound in the discontinuous phase can be tilt-uniaxially aligned. The inclination angle of the magnetic pole is preferably 10 degrees or more and less than 80 degrees. Further, it is preferable to apply a magnetic field in a temperature range in which the liquid crystalline compound forms a liquid crystal phase, and to irradiate ultraviolet rays in the alignment state to fix the tilt alignment state.

At least one of the above (1) to (4) is used to perform tilted uniaxial orientation. The tilt angle of the liquid crystal compound is preferably 10 degrees or more and less than 80 degrees, and more preferably 20 degrees or more and less than 60 degrees. After the tilt alignment of the liquid crystal compound, it is preferable to fix the tilt alignment state by irradiating ultraviolet rays. The irradiation light wavelength, irradiation light amount, light source, and substrate temperature during irradiation in the ultraviolet irradiation polymerization are the same as those in the above-described photo-alignment method. When the photo-alignment method is used, it is preferable that the irradiation light wavelength used for photo-alignment and the irradiation light wavelength for photopolymerizing the polymerizable liquid crystalline compound be different.

The dispersion is prepared as described above, coated on a transparent support, and the liquid crystal molecules are aligned by irradiating linearly polarized light, and if necessary, the liquid crystal molecules in the aligned state are photopolymerized. An isotropic scattering layer can be produced. It is also preferable to provide an anisotropic scattering layer on a transparent support.

[Transparent Support] The transparent support is preferably formed from a material having a light transmittance of 80% or more.
As the transparent support, a polymer film can be used. Examples of the polymer include polyolefin (eg, polyethylene), norbornene resin, polyethylene terephthalate, polyethylene naphthalate, polypropylene,
Polycarbonate, polystyrene, polyarylate, polysulfone, polyether sulfone, polyvinyl chloride, polyvinyl alcohol, cellulose ester (eg,
Cellulose acetate). A film in which two or more kinds of polymers are mixed may be used. Commercially available polymer (eg, ZEONEX, ZEONOR, ZEON CORPORATION)
ARTON, manufactured by Nippon Synthetic Rubber Co., Ltd .; Fujitac (manufactured by Fuji Photo Film Co., Ltd.) can also be used. Fujitac (Fuji Photo Film Co., Ltd.)
), Polyethylene terephthalate, polyethylene naphthalate, polycarbonate, and Zeonor (manufactured by Nippon Zeon Co., Ltd.). The transparent support has transparency,
Physical properties such as appropriate moisture permeability, low birefringence, and appropriate rigidity are required, and when viewed comprehensively, cellulose acylates are preferred, and cellulose acetate is particularly preferred.

The physical properties of the transparent support can be any value depending on the application, but typical preferable values for use in a normal transmission type LCD are shown below. The thickness is preferably 5 to 500 μm from the viewpoint of handleability and durability, and is preferably 20 to 20 μm.
0 μm is more preferable, and 20 to 100 μm is particularly preferable. The retardation value is 0 at 632.8 nm.
150 nm is preferable, 0 to 20 nm is more preferable,
0-5 nm is particularly preferred. It is preferable that the slow axis of the transparent support is substantially parallel or perpendicular to the absorption axis of the polarizing film, from the viewpoint of avoiding elliptical linear polarization. However, when the transparent support is provided with a function of changing the polarization property such as a retardation plate, this is not a limitation, and the absorption axis of the polarizing film and the slow axis of the transparent support may take an arbitrary angle. it can. Visible light transmittance is preferably 60% or more,
90% or more is particularly preferred. The dimensional decrease after the treatment at 90 ° C. for 120 hours is preferably from 0.3 to 0.01%, particularly preferably from 0.15 to 0.01%.
Tensile value by the tensile test of the film is 50 to 10
00 MPa is preferred, and 100 to 300 MPa is particularly preferred. The moisture permeability of the film is 100 to 800 g / m ²
-Day is preferred, and 300 to 600 g / m ² · day
Is particularly preferred.

The cellulose acylate preferable as the transparent support has a degree of substitution of cellulose with a hydroxyl group which satisfies all of the following formulas (I) to (III).

(I) 2.6 ≦ A + B ≦ 3.0 (II) 2.0 ≦ A ≦ 3.0 (III) 0 ≦ B ≦ 0.8 In the formula, A and B are substituted by hydroxyl groups of cellulose. A represents a substituent of an acyl group, A represents a degree of substitution of an acetyl group,
B is the degree of substitution of an acyl group having 3 to 5 carbon atoms.
Cellulose has three hydroxyl groups per glucose unit, and the above numbers indicate the degree of substitution for the hydroxyl group 3.0, with the maximum degree of substitution being 3.0. Cellulose triacetate generally has a degree of substitution of A of 2.6 or more and 3.0 or less (in this case, there are as many as 0.4 unsubstituted hydroxyl groups), and the case of B = 0 is cellulose triacetate. Cellulose acylate used as a polarizing film transparent support is a cellulose triacetate in which all acyl groups are acetyl groups, and an acyl group having an acetyl group of 2.0 or more and 3 to 5 carbon atoms of 0.8 or less is substituted. Those having no more than 0.4 hydroxyl groups are preferred. In the case of an acyl group having 3 to 5 carbon atoms, 0.3 or less is particularly preferable from the viewpoint of physical properties. The degree of substitution can be obtained by measuring the degree of binding between acetic acid and a fatty acid having 3 to 5 carbon atoms that substitute for the hydroxyl group of cellulose, and calculating the degree of substitution. The measurement can be performed according to ASTM D-817-91.

Other acyl groups having 3 to 5 carbon atoms of an acetyl group include a propionyl group (C ₂ H ₅ CO—), a butyryl group (C ₃ H ₇ CO—) (n-, iso-), and a valeryl group ( C _{4
H 9 CO -) (n-,} iso-, sec-, tert- with) those of these out n- substitutions mechanical strength when formed into a film, preferably from ease or the like is dissolved, especially n- A propionyl group is preferred. When the degree of substitution of the acetyl group is low, the mechanical strength and the moist heat resistance are reduced. When the degree of substitution of the acyl group having 3 to 5 carbon atoms is high, the solubility in an organic solvent is improved. However, if the degree of substitution is within the above range, good physical properties are exhibited.

The polymerization degree (average viscosity) of the cellulose acylate is preferably from 200 to 700, and more preferably from 250 to 550.
Are preferred. The viscosity average degree of polymerization can be measured by an Ostwald viscometer, and is determined by the following equation from the measured intrinsic viscosity [η] of cellulose acylate. DP = [η] / Km (where DP is the viscosity average degree of polymerization, Km
Is the constant 6 × 10 ^-4 )

As the cellulose as the cellulose acylate raw material, cotton linter or wood pulp can be used. A mixture of cotton linter and wood pulp may be used. Cellulose acylate is usually produced by a solvent casting method. In the solvent casting method, a concentrated solution (hereinafter, referred to as a dope) is prepared by dissolving cellulose acylate and various additives in a solvent, and then casting the solution on an endless support such as a drum or a band. It evaporates to form a film. The concentration of the dope is preferably adjusted so that the solid content is 10 to 40% by mass. The surface of the drum or band
It is preferable that the mirror surface is finished. The casting and drying methods in the solvent casting method are described in U.S. Pat. Nos. 2,336,310, 2,367,603 and 249.
No. 2078, No. 2492977, No. 2492978
Nos. 2607704, 2739069 and 27
39070, UK Patents 640731, 73689
No. 2, each Japanese Patent Publication No. 45-4554 and No. 49-5
No. 614, JP-A-60-176834 and JP-A-60-20
No. 3430 and No. 62-115035.

A method of casting two or more layers of dope is also preferably used. In the case of casting a plurality of dopes, a film containing a dope may be cast and stacked from a plurality of casting ports provided at intervals in the traveling direction of the support to form a film. 61-158414
JP-A-1-122419, JP-A-11-1982
No. 85, etc. can be applied. Alternatively, the film may be formed by casting a cellulose acylate solution from two casting ports.
0-27562, JP-A-61-94724, JP-A-61-947245, JP-A-61-104814,
JP-A-61-158413, JP-A-6-134933
No., can be carried out by the method described in. Also, Japanese Patent Application Laid-Open No. 56-1
The casting method described in Japanese Patent No. 62617 in which a high-viscosity dope is wrapped with a low-viscosity dope and the high- and low-viscosity dope is simultaneously extruded is also preferably used.

Examples of organic solvents that dissolve cellulose acylate include hydrocarbons (eg, benzene, toluene), halogenated hydrocarbons (eg, methylene chloride, chlorobenzene), alcohols (eg, methanol, ethanol, diethylene glycol), Ketones (eg, acetone), esters (eg, ethyl acetate, propyl acetate) and ethers (eg, tetrahydrofuran, methyl cellosolve) are included. Halogenated hydrocarbons having 1 to 7 carbon atoms are preferably used, and methylene chloride is most preferably used. From the viewpoint of physical properties such as solubility of cellulose acylate, peeling property from a support, mechanical strength of a film, and optical properties, one or more alcohols having 1 to 5 carbon atoms are mixed in addition to methylene chloride. Is preferred. The content of the alcohol is preferably from 2 to 25% by mass, more preferably from 5 to 20% by mass, based on the whole solvent. Examples of alcohols include methanol, ethanol, n-propanol, isopropanol and n-butanol. Preference is given to methanol, ethanol, n-butanol or mixtures thereof.

In addition to cellulose acylate, components that become solids after drying include a plasticizer, an ultraviolet absorber, inorganic fine particles,
It includes a heat stabilizer, an antistatic agent, a flame retardant, a lubricant, an oil agent, a release accelerator from a support, and a hydrolysis inhibitor for cellulose acylate. As the heat stabilizer, a salt of an alkaline earth metal (calcium, magnesium) can be used.

As a plasticizer, a phosphoric acid ester or a carboxylic acid ester is used. Examples of phosphate esters include triphenyl phosphate (TPP) and tricresyl phosphate (TCP), cresyl diphenyl phosphate, octyl diphenyl phosphate, diphenyl biphenyl phosphate, trioctyl phosphate, tributyl phosphate. It is. Representative carboxylic esters include phthalic esters and citric esters. Examples of phthalate esters include dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DB
P), dioctyl phthalate (DOP), diphenyl phthalate (DPP) and diethylhexyl phthalate (DEHP). Examples of citrate esters include:
O-acetyl triethyl citrate (OACTE) and O-acetyl tributyl citrate (OACTB), acetyl triethyl citrate, acetyl tributyl citrate are included. Examples of other carboxylic esters include butyl oleate, methylacetyl ricinoleate,
Trimellitic esters such as dibutyl sebacate and trimethyl trimellitate are included. Examples of glycolic acid esters include triacetin, tributyrin, butylphthalylbutyl glycolate, ethylphthalylethyl glycolate, methylphthalylethyl glycolate, butylphthalylbutyl glycolate.

Triphenyl phosphate, biphenyl diphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, tributyl phosphate, dimethyl phthalate, diethyl phthalate, dibutyl phthalate, dioctyl phthalate, diethyl hexyl phthalate, triacetin, ethyl phthalyl Ethyl glycolate and trimethyl trimellitate are preferred, and triphenyl phosphate, biphenyl diphenyl phosphate, diethyl phthalate, ethyl phthalyl ethyl glycolate and trimethyl trimellitate are more preferred. Two or more plasticizers may be used in combination. The amount of the plasticizer added is preferably 5 to 30% by mass, more preferably 8 to 16% by mass, based on the cellulose acylate. The plasticizer may be added together with the cellulose acylate or the solvent when preparing the cellulose acylate solution, or may be added during or after the solution preparation.

The ultraviolet absorber is a salicylic acid ester type,
A benzophenone-based, benzotriazole-based, benzoate-based, cyanoacrylate-based or nickel complex-based ultraviolet absorber can be used. Benzophenone-based, benzotriazole-based, and salicylate-based ultraviolet absorbers are preferred. Examples of the benzophenone-based ultraviolet absorber include 2,4-dihydroxybenzophenone, 2-hydroxy-4-acetoxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2,2′-di-hydroxy-4-methoxybenzophenone, , 2'-Di-hydroxy-4,4'-methoxybenzophenone, 2-hydroxy-4-n-octoxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone, 2-hydroxy-4- (2-hydroxy-3 -Methacryloxy) propoxybenzophenone. Examples of the benzotriazole-based ultraviolet absorber include 2- (2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-
5-chlorobenzotriazole, 2- (2'-hydroxy-5'-tert-butylphenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'-di-tert-
Amylphenyl) benzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-tert-butylphenyl)-
5-chlorobenzotriazole, 2- (2'-hydroxy-5'-tert-octylphenyl) benzotriazole. Examples of the salicylate-based ultraviolet absorber include phenyl salicylate, p-octylphenyl salicylate, and p-tert-butylphenyl salicylate. 2-hydroxy-4-methoxybenzophenone, 2,2'-di-hydroxy-4,4'-methoxybenzophenone, 2- (2'-hydroxy-3'-tert-
Butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-5'-tert-butylphenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'-di- tert-amylphenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'
-Di-tert-butylphenyl) -5-chlorobenzotriazole is particularly preferred. It is particularly preferable to use a plurality of absorbers having different absorption wavelengths in combination, since a high blocking effect can be obtained in a wide wavelength range. The amount of the ultraviolet absorber is 0.01 to 5% by mass based on the cellulose acylate.
Is preferable, and 0.1 to 3% by mass is particularly preferable. The ultraviolet absorber may be added simultaneously with dissolution of the cellulose acylate, or may be added to the dope after dissolution. In particular, a mode in which an ultraviolet absorbent solution is added to the dope immediately before casting using a static mixer or the like is preferable.

The inorganic fine particles to be added to the cellulose acylate include silica, kaolin, talc, diatomaceous earth,
Quartz, calcium carbonate, barium sulfate, titanium oxide, alumina and the like can be arbitrarily used according to the purpose.
Before adding these fine particles to the dope, a high-speed mixer,
It is preferable to perform dispersion in the binder solution by any means such as a ball mill, an attritor, and an ultrasonic disperser. Cellulose acylate is preferred as the binder. It is also preferable to carry out dispersion with other additives such as an ultraviolet absorber. The dispersion solvent is optional, but preferably has a composition close to that of the dope solvent. The number average particle size of the dispersed particles is 0.0
It is preferably from 1 to 100 μm, particularly preferably from 0.1 to 10 μm. The above dispersion may be added to the cellulose acylate dissolving step at the same time or may be added to the dope in any step. However, like the ultraviolet absorber, the dispersion is added immediately before casting using a stirrer (eg, a static mixer). Is preferred.

As the release accelerator from the support, a surfactant is effective and is not particularly limited, such as phosphoric acid type, sulfonic acid type, carboxylic acid type, nonionic type and cationic type.
Surfactants that can be used as a release accelerator are described in JP-A-61-243837.

When a cellulose acylate film is used for the transparent support, it is preferable to impart hydrophilicity by surface-treating the film in order to enhance the adhesion to the constituent polymer of the polarizing film (for example, a polyvinyl alcohol resin). . The hydrophilizing surface treatment includes saponification treatment, corona treatment, flame treatment and glow discharge treatment. Further, a hydrophilic resin may be dispersed in a solvent having an affinity for cellulose acylate, and a thin layer may be applied. Among the above means, saponification treatment is particularly preferable because the flatness and physical properties of the film are not impaired. The saponification treatment is performed by immersing the film in an alkaline aqueous solution such as caustic soda.
After the treatment, it is preferable to neutralize with a low-concentration acid and sufficiently wash with water in order to remove excess alkali.

On the surface of the transparent support of the polarizing element, an optically anisotropic layer for compensating the viewing angle of the LCD (Japanese Patent Laid-Open No. 4-2298).
No. 28, No. 6-75115, and No. 8-50206), an antiglare layer and an antireflection layer for improving the visibility of the display, and a hard coat layer for increasing the scratch resistance of the polarizing film. In addition, a gas barrier layer for suppressing the diffusion of moisture or oxygen, a polarizing film or an adhesive layer for easily increasing the adhesion to an adhesive or a pressure-sensitive adhesive, a layer for imparting slipperiness, or any other functional layer can be provided. The optically anisotropic layer is preferably formed from discotic liquid crystalline molecules. The functional layer may be provided on the polarizing layer side, or may be provided on the surface opposite to the polarizing layer, and can be appropriately selected according to the purpose.

Various functional films can be directly bonded to one or both sides of the polarizing element as a transparent support. Examples of the functional film include retardation films such as a λ / 4 plate and a λ / 2 plate,
It includes a light diffusion film, a plastic cell provided with a conductive layer on the surface opposite to the polarizing element, a brightness enhancement film having anisotropic scattering and anisotropic optical interference functions, a reflector and a reflector having a semi-transmission function.

In order to increase the adhesive strength between the transparent support and the polymer medium of the anisotropic scattering layer, it is preferable to apply an undercoat layer or a surface treatment. Preferred materials for the undercoat layer are gelatin, styrene-butadiene rubber, and polyvinyl alcohol. Preferred surface treatments are flame treatment, corona treatment, glow treatment, and saponification treatment.

[Anisotropic scattering layer composed of optically anisotropic continuous phase and optically isotropic discontinuous phase] The optically anisotropic continuous phase is
It is preferable that the same rod-like liquid crystalline compound as the above-mentioned optically anisotropic discontinuous phase is tilted uniaxially oriented. The kind of the compound to be used is the same as the above-mentioned optically anisotropic discontinuous phase. As the orientation method, a stretching method cannot be used, but a photo-orientation method, an electric-field orientation method, and a magnetic-field orientation method can be preferably used similarly to the above-described orientation of the optically anisotropic discontinuous phase.
When the optically anisotropic phase is a continuous phase, a polymer such as polyimide or polyvinyl alcohol is coated as an alignment film on a transparent support, and rubbing or irradiation with linearly polarized light is used to impart a large tilt angle alignment. Is also preferably performed. The preferred thickness of the alignment film is 0.01
It is not less than μm and not more than 5 μm. The optically isotropic discontinuous phase is
Crosslinked or non-crosslinked polymer particles such as polymethyl methacrylate and polystyrene, and inorganic particles such as silica, titanium dioxide, zinc oxide, tungsten oxide, and tin oxide can be preferably used. The preferred particle size of the optically isotropic discontinuous phase is the same as the aforementioned optically anisotropic discontinuous phase.
The preferable use amount of the optically isotropic discontinuous phase is preferably 0.001 to 2.0 g per 1 g of the material constituting the optically anisotropic continuous phase. More preferred is 0.01 to 1.5 g. A method of fixing the orientation by irradiating ultraviolet rays after the optically anisotropic continuous phase is tilted is preferably carried out similarly to the above-mentioned discontinuous optically anisotropic phase. It is also preferable to provide the anisotropic scattering layer of the present invention on a transparent support. The transparent support used is the same as described above.

A polarizing element having an anisotropic scattering layer is preferably used as a light scattering polarizing element in combination with a light absorbing polarizing element. The light-absorbing polarizing element is a polarizing element that absorbs one of orthogonal linearly polarized light and substantially transmits the other, and contains I ₃ − and / or I ₅ − and / or I / − in a polyvinyl alcohol film stretched 5 times or more. Generally, organic dichroic dyes are highly uniaxially oriented and crosslinked with boric acid and sandwiched with a protective film such as cellulose triacetate. The degree of polarization (defined by the following formula) of such a light-absorbing polarizing element is preferably 99% or more, and the average light transmittance from 400 nm to 700 nm is desirably 40% or more.

[0090]

(Equation 1)

Where P is the transmittance of light passing through two polarizing elements with transmission axes parallel; and C is the transmission of light passing through two polarizing elements with transmission axes orthogonal. Rate.

The combination with an optical film having an anisotropic scattering layer may be used as a light-absorbing polarizing element and a separate polarizing element as shown in FIG. 6, or as shown in FIGS. One of the protective films of the absorption type polarizing element may be replaced and used integrally with the light absorption type element. At this time, it is desirable to use the polarizing element having the anisotropic scattering layer so that the transmission axis of the polarizing element is substantially parallel to the transmission axis of the light absorbing polarizing element. Further, the polarizing element having the transmission axis anisotropic scattering layer of the anisotropic scattering layer is desirably arranged so that the anisotropic scattering layer is located outside the light absorption type polarizing element (the opposite side of the liquid crystal cell). .

When light entering the liquid crystal display device from outside light or a front light passes through a polarizing element having an anisotropic scattering layer, it scatters one of orthogonal linearly polarized lights and substantially transmits the other. The transmitted linearly polarized light then passes through the light-absorbing polarizing element and enters the liquid crystal cell. In the polarizing element of the present invention, it is preferable that at least 50% or more of the other scattered linearly polarized light is forward scattered. Since the scattered light passes through the tilted uniaxially oriented anisotropic discontinuous phase or continuous phase at a fixed azimuth, the polarization state depends on the magnitude of the retardation of the anisotropic discontinuous phase or continuous layer. Change. The retardation of the polarizing element of the present invention is preferably 50 nm or more and less than 1000 nm, and more preferably 150 nm or more and less than 400 nm. The azimuth between the scattered light and the tilted uniaxially oriented anisotropic discontinuous phase or continuous phase depends on the tilt angle of the slow axis of the uniaxially oriented anisotropic discontinuous phase or continuous phase. The azimuth increases as the inclination angle of the slow axis increases, but the azimuth does not exceed the inclination angle of the slow axis. The inclination angle of the slow axis is preferably 10 degrees or more and less than 80 degrees, and more preferably 2 degrees or less.
0 degrees or more and less than 60 degrees. In addition, as the emission angle of the scattered light increases, the path length to the emission increases, and the azimuth of the anisotropic discontinuous phase or continuous phase with the slow axis increases, so that the change in the polarization state also increases. It is ideal for the scattered light to pass through an anisotropic discontinuous phase or a continuous phase having a retardation of about 275 nm corresponding to a λ / 2 plate at an azimuth angle of 45 ° in order to increase the amount of transmitted light of the light absorption type polarizing element. However, the incident light in the reflection type liquid crystal display device is complicated because it uses various light sources such as front light, sunlight, and indoor lighting arranged at various distances and angles, and also has a scattering angle distribution. Also, the polarization state of the scattered light actually has a distribution. In the polarizing element of the present invention, at least 10% of the emitted scattered light can be converted into elliptically polarized light or linearly polarized light having an azimuth of 20 degrees or more with respect to the scattering axis.

Further, in a transmissive liquid crystal display device, a polarizing element can be provided between a backlight and a polarizing film to exhibit an effect of improving luminance.

When the polarizing element is combined with an optical compensation film of a liquid crystal display device as shown in FIG. 8, a wide viewing angle and high luminance can be achieved. It is preferable to use the discotic compound described in Japanese Patent No. 2587398 as the optical compensation film. Further, an optical compensatory film integrated with a polarizing element can be preferably used (described in JP-A-7-191217). Further, by combining the polarizing element with a λ / 4 plate as shown in FIG. 9, the thickness of the reflection type liquid crystal display device can be reduced. Here, it is preferable that the transmission axes of the (light scattering type and light absorption type) polarizing elements and the slow axis of the λ / 4 plate be arranged at substantially 45 °.

An anti-reflection layer can be provided on the surface of the polarizing element. The anti-reflection layer reduces surface reflections and, as a result, can increase the brightness of the display.
This anti-reflection layer is described in, for example, Journal of the Photographic Society of Japan, 29, p. 1
37 (1966), or a laminate of a low refractive index layer and a high refractive index layer, or a structure in which only one low refractive index layer is provided.

By using the polarizing element in the reflection type liquid crystal display device, the light use efficiency is increased, and as a result, the brightness of the display is increased.

[0098]

[Example 1] (Preparation of coating liquid for anisotropic scattering layer) 4g of a polymerizable liquid crystal compound (N49) having a smectic C phase, a mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate (DPHA, manufactured by Nippon Kayaku Co., Ltd.) 0.1 g, photopolymerization initiator (Irgacure 90
7, Ciba-Geigy) (0.1 g) was dissolved in ethyl acetate (2 g) and filtered through a polypropylene filter having a pore size of 30 μm to prepare a polymerizable liquid crystal solution for a discontinuous phase. on the other hand,
Polyvinyl alcohol (PVA205, Kuraray Co., Ltd.)
0.2 g of sodium dodecylbenzenesulfonate as a surfactant was added to 120 g of a 10% by mass aqueous solution,
After dissolution, the solution was filtered through a polypropylene filter having a pore size of 30 μm to prepare an aqueous solution for a continuous phase. A liquid obtained by mixing 200 g of the polymerizable liquid crystal solution for the discontinuous phase and 200 g of the aqueous solution for the continuous phase was dispersed with a homogenizer to prepare a coating liquid for an anisotropic scattering layer. The average dispersion diameter of the discontinuous phase is 0.3 μm
Met.

(Preparation of Coated Film and Oblique Orientation by Stretching Method) The coating solution for the anisotropic scattering layer was band-cast using a die,
It was dried to have a thickness of 40 μm. The film was peeled off from the band, stretched 1.5 times at 25 ° C. in a dry state, and then aged at 90 ° C. for 2 minutes.
Air-cooled metal halide lamp (manufactured by Eye Graphics Co., Ltd., wavelength range 200 to 500 nm, maximum wavelength 36)
5 nm), illuminance 200 mW / cm ² , irradiation amount 4
The discontinuous phase was cured by irradiating it with an ultraviolet ray of 00 mJ / cm ² to prepare a polarizing element.

[Example 2] (Preparation of coating liquid for anisotropic scattering layer) Liquid crystal compound (N-1)
5) 4 g, 0.4 g of the photochemically reactive compound (WP-1),
0.1 g of a photopolymerization initiator (Irgacure 907, manufactured by Ciba Geigy) and 2 g of ethyl acetate were mixed with 120 g of a 10% by mass aqueous solution of polyvinyl alcohol (PVA205, manufactured by Kuraray Co., Ltd.), and the liquid was dispersed using a homogenizer. Thus, a coating solution for an anisotropic scattering layer was prepared. The average diameter of the discontinuous phase was 0.4 μm.

(Preparation of Fine Particle Dispersion) A fine particle dispersion having the following composition was prepared and dispersed by an attritor so that the volume average particle diameter became 0.7 μm.

<< Composition of Fine Particle Dispersion >>シ リ カ Silica (Aerosil R972 manufactured by Nippon Aerosil Co., Ltd.) 0.67% by mass cellulose acetate (degree of substitution 2.8) 2.93 mass% triphenyl phosphate 0.23 mass% biphenyl diphenyl phosphate 0.12 mass% methylene chloride 88.37 mass% methanol 7.68 mass% ──────────────────────────

(Preparation of Raw Material Dope) A raw material of cellulose triacetate having the following composition was prepared.

{Raw Material Composition of Cellulose Triacetate}セ ル ロ ー ス Cellulose triacetate having a degree of substitution of 2.8 89.3% by mass 7.1% by mass of triphenyl phosphate % Biphenyl diphenyl phosphate 3.6% by mass ────────────────────────────────────

To a cellulose triacetate raw material having a solid content of 100 parts by mass, 17.9 parts by mass of a fine particle dispersion was added, and a mixed solvent consisting of 92% by mass of dichloromethane and 8% by mass of methanol was appropriately added thereto. Was prepared. The solid content of the dope was 18.5% by mass. This dope is filtered with a filter paper (# 63, manufactured by Toyo Roshi Kaisha, Ltd.)
, And further filtered through a sintered metal filter (06N, Nippon Seisen Co., Ltd., nominal pore size 10 μm), and further filtered through a mesh filter (RM, Nippon Pole Co., Ltd., nominal pore size 45 μm).

(Preparation of Ultraviolet Absorbent Solution) An ultraviolet absorbent solution having the following composition was prepared and filtered with a filter (Astrophore 10 filter, manufactured by Fuji Photo Film Co., Ltd.).

<< Composition of UV Absorber Solution >> ２− 2- (2'-hydroxy-3 ', 5'-di-tert-butylphenyl ) -5-Chlorobenzotriazole 5.83% by mass 2- (2'-hydroxy-3 ', 5'-di-tert-amylphenyl) benzotriazole 11.66% by mass Cellulose acetate having a degree of substitution of 2.8 1 .48 mass% triphenyl phosphate 0.12 mass% biphenyl diphenyl phosphate 0.06 mass% methylene chloride 74.38 mass% methanol 6.47 mass% ─────────────────────

(Preparation of transparent support)
Using a static mixer, the above ultraviolet absorbent solution,
The dope was added and mixed in the pipe route of the dope while adjusting the amount of the ultraviolet absorber to 1.04% by mass with respect to the solid content in the dope. This dope was cast on an endless belt, dried with hot air until it had self-supporting properties, and peeled off as a film. The residual solvent at the time of peeling was 38% by mass. The film was introduced into a tenter type dryer, dried while applying tension while holding both ends, and dried until the residual solvent became 14% by mass. Thereafter, drying was performed in a roller drying zone until the residual solvent became 0.1% by mass. The thickness of the finished film is 80 μm, the retardation is (3.1) nm, and the tensile strength in the longitudinal direction of the film is 140M.
Pa.

(Measurement of Residual Solvent Amount) As the residual solvent, methylene chloride, methanol and n-butanol were quantified using GC-18A manufactured by Shimadzu Corporation. The residual solvent amount is based on the wet amount, and indicates the ratio of the sum of these solvents to the total mass of the sample containing the solvent.

(Measurement of Dope Solids Concentration) The dope solids concentration (%) was determined by (wet weight of dope heated at 120 ° C. for 2 hours) / (original dope mass) × 100 on a wet basis.

(Measurement of Particle Dispersion Particle Size) Measurement was carried out using a master sizer MS20 manufactured by MALVERN.

(Measurement of Film Retardation) The retardation was measured by an automatic birefringence meter KOB manufactured by Oji Keisoku Co., Ltd.
The value at 632.8 nm was measured with RA21DH.

(Measurement of Tensile Strength of Film) Tensile strength was measured at 23 ° C. and 65% RH using an RTA-100 tensile tester manufactured by Orientec Co., under conditions of an initial sample length of 100 mm and a tensile speed of 200 mm / min. It was measured.

(Preparation of Coating Film and Tilt Orientation by Photo Alignment Method) The prepared 80 μm-thick triacetyl cellulose film was used as a transparent support, and the prepared coating solution for an anisotropic scattering layer was coated thereon with a bar coater. Apply using
Dry at 100 ° C. for 5 minutes. The thickness was 8 μm. Thereafter, using an ultraviolet exposure apparatus, a linearly polarized light of 313 nm was irradiated at an irradiation light intensity of 10 m from an oblique upper direction of 45 degrees with respect to the substrate.
Irradiation was performed for 10 minutes at a substrate temperature of 70 ° C. at W / cm ² . This film together with the support was left in a thermostat at 100 ° C. for 2 minutes, aged, and then used with a 160 W / cm air-cooled metal halide lamp (manufactured by Eye Graphics Co., Ltd., wavelength range 200 to 500 nm, maximum wavelength 365 nm). Illuminance 200mW / cm ² , irradiation amount 400mJ / c
Irradiation with ultraviolet rays of m ² was carried out to cure while maintaining the tilted orientation state of the discontinuous phase, thereby producing a polarizing element.

Example 3 (Preparation of Coating Solution for Anisotropic Scattering Layer) At room temperature, 4 g of liquid crystal compound (N-18), 0.1 g of photopolymerization initiator (Irgacure 907, manufactured by Ciba Geigy), average Vinegar degree 5
A coating solution was prepared by mixing 12 g of 9.0% cellulose acetate, 54.3 g of methylene chloride, 9.9 g of methanol and 2.0 g of n-butanol.

(Preparation of Coated Film and Tilt Orientation by Electric Field) The coating liquid for the anisotropic scattering layer was cast on a glass plate, dried at room temperature for 1 minute, and then dried at 45 ° C. for 5 minutes. The residual amount of the solvent after drying was 30% by mass. The cellulose acetate film was peeled off from the glass plate, cut into an appropriate size, and then dried at 120 ° C. for 30 minutes. The residual amount of the solvent was 0.1% by mass, and the thickness of the film was:
It was 97 μm. When an ultrathin section of the film cross section was observed with a transmission electron microscope, the average diameter of the discontinuous phase composed of a liquid crystalline compound was 2.3 μm. After this, the substrate temperature 80
The film was inserted at 45 ° C. between the electrodes inclined at 45 ° to the substrate, and a voltage of 500 V was applied for 5 minutes. Voltage applied to 3
Minutes, a 160 W / cm air-cooled metal halide lamp (manufactured by Eye Graphics Co., Ltd., wavelength range 20)
(0-500 nm, maximum wavelength: 365 nm), the film is irradiated with ultraviolet light having an illuminance of 200 mW / cm ² and an irradiation amount of 400 mJ / cm ² to cure the film while maintaining the inclined orientation state of the discontinuous phase, thereby producing a polarizing element. did.

Example 4 (Preparation of Coating Solution for Anisotropic Scattering Layer) At room temperature, 4 g of liquid crystal compound (N-17), 0.1 g of photopolymerization initiator (Irgacure 907, manufactured by Ciba Geigy), average Particle size 2.1μm
1.3 g of silica particles, 27 g of methyl ethyl ketone, and 27 g of cyclohexanone were mixed and dispersed to prepare a coating solution.

(Preparation of Coated Film and Tilt Orientation by Magnetic Field) A triacetyl cellulose film having a thickness of 80 μm prepared in Example 2 was coated with 0.2 μm of polyvinyl alcohol as an alignment film and rubbed. The coating liquid D for an anisotropic scattering layer was applied thereon using a bar coater, and dried at 100 ° C. for 5 minutes. The film thickness was 9 μm.
Thereafter, the film was inserted between magnetic poles inclined at 45 ° to the substrate at a substrate temperature of 90 ° C., and a magnetic field of 2 T was applied for 5 minutes. When a magnetic field was applied for 3 minutes, a 160 W / cm air-cooled metal halide lamp (Eye Graphics Co., Ltd.)
Made, wavelength range 200-500nm, maximum wavelength 365n
m), illuminance 200 mW / cm ² , irradiation amount 400
The film was irradiated with ultraviolet rays of mJ / cm ² and cured while maintaining the tilted state of the discontinuous phase to prepare a polarizing element.

(Evaluation of Polarizing Element) The light transmittance and the light scattering property (haze) of the polarizing elements prepared in Examples 1 to 4 were measured using a haze meter MODEL 1001DP (manufactured by Nippon Denshoku Industries Co., Ltd.). . The measurement was performed by inserting a light-absorbing polarizing element and the prepared light-scattering polarizing element between the light source and the film, and making the transmission axis of the light-absorbing polarizing element and the transmission axis of the light-scattering polarizing element the same. Are made parallel and perpendicular to each other. The light transmittance was evaluated using the total light transmittance, and the light scattering property was evaluated using haze as an index. The results are shown in Table 1. In the polarizing element according to the present invention, the parallel and orthogonal transmittances were both high, and the haze was large in the orthogonal direction, but small in the parallel direction. Therefore, the light in the transmission axis direction incident on the anisotropic scattering layer is largely unaffected by the scattering and is largely transmitted, and the light in the scattering axis direction is largely scattered but is not scattered backward but forward (incident light). Out of the surface).

[0120]

Table 1 Total light transmittance haze polarizing element Parallel orthogonal parallel orthogonal ──────────────────────────────────── Example 1 90.2% 88.5 % 13.2% 90.4% Example 2 91.5% 70.1% 9.8% 89.8% Example 3 86.9% 82.1% 13.5% 92.1% Example 4 87.4% 69.6% 10.2% 85.3% ────────────────────────────────── ──

Example 5 (Integration of Light-Absorbing Polarizing Element and Light-Scattering Polarizing Element) A polyvinyl alcohol (PVA) film was prepared using iodine 5.0.
g / l, 10.0 g / l of potassium iodide in an aqueous solution at 25 ° C. for 90 seconds, and further 10 g of boric acid
After immersion in an aqueous solution at 25 ° C. for 60 seconds, the film was stretched 7.0 times using a roll stretching machine. Thereafter, the polarizing element prepared in Example 1 was stacked on one side of the stretched film, and the two stacked films were washed with a 5% by mass aqueous solution of polyvinyl alcohol (PVA117, Kuraray Co., Ltd.) as glue. Two triacetylcellulose films (Fuji Photo Film Co., Ltd.) were laminated. At the time of lamination, they were arranged such that the transmission axis of the light-scattering polarizing element and the transmission axis of the light-absorbing polarizing element were substantially parallel. Thereafter, drying was performed at 70 ° C. for 5 minutes to produce a polarizing plate.

Example 6 (Integration of Light Absorbing Polarizing Element and Anisotropic Polarizing Element) A polyvinyl alcohol (PVA) film was 5.0 g of iodine.
/ L, an aqueous solution of 10.0 g / l of potassium iodide at 25 ° C for 90 seconds.
After immersion in a liter aqueous solution at 25 ° C. for 60 seconds, the film was stretched 7.0 times using a roll stretching machine. Thereafter, the stretched film was formed by using the polarizing element prepared in Example 2, a saponified triacetyl cellulose film (manufactured by Fuji Photo Film Co., Ltd.), and polyvinyl alcohol (PVA117,
Lamination was performed using a 5% by mass aqueous solution of Kuraray Co., Ltd. as a paste. At the time of lamination, the transmission axis of the light-scattering polarizing element and the transmission axis of the light-absorbing polarizing element were substantially parallel to each other, and the light-scattering polarizing element was arranged to be in contact with the light-absorbing polarizing element. Thereafter, drying was performed at 70 ° C. for 5 minutes to obtain a polarizing plate.

Example 7 (Integration of Light-Absorbing Polarizing Element and Anisotropic Polarizing Element) In the production of the polarizing plate of Example 6, the polarizing element to be laminated was changed to the polarizing element produced in Example 3. Except for the above, a polarizing plate was produced according to the method described in Example 6.

Example 8 (Integration of Light Absorbing Polarizing Element and Anisotropic Polarizing Element) In the production of the polarizing plate of Example 6, the polarizing element to be laminated was changed to the polarizing element produced in Example 4. Except for the above, a polarizing plate was produced according to the method described in Example 6.

[Comparative Example 1] A saponified cellulose triacetate film (Fuji Photo Film Co., Ltd.) was prepared by laminating a polarizing element to be laminated in the production of the polarizing plate of Example 6.
The polarizing plate was manufactured according to the method described in Example 6, except that the polarizing plate was changed to the following.

[Comparative Example 2] The polarizing plate manufactured in Comparative Example 1 was
A polarizing plate was manufactured by arranging a commercially available brightness enhancement film (manufactured by DBEF, 3M) having a polarization selection layer due to optical interference so that the transmission axes of both films were substantially parallel.

(Evaluation of Anisotropy of Diffuse Transmittance) Examples 5 to 8
The diffusion transmittance of the polarizing plates prepared in Comparative Examples 1 and 2 was measured using a spectrophotometer (UV-3100P) equipped with a 60φ integrating sphere.
C, manufactured by Shimadzu Corporation) using a device equipped with a large polarizer (Assy). The measurement is performed by inserting a large polarizer between the light source and the film, and the parallel transmittance is obtained when the transmission axis of the polarizer and the transmission axis of the anisotropic scattering polarizer are combined, and the orthogonal transmittance is obtained when the transmission axis is orthogonal. Was measured. Measurement is 40
The measurement was performed in the range of 0 nm to 700 nm, and the average value was calculated.

The evaluation results are shown in Table 2. The polarizing plate according to the present invention has a higher orthogonal transmittance than the polarizing plate of the comparative example.
Therefore, even in an environment where reflection and backscattering cannot be used, the amount of light incident on the liquid crystal cell can be increased.

[0129]

[Table 2] Table 2 全 Polarizing plate Total when parallel Light transmittance Total light transmittance in case of orthogonal 直交 Example 5 79.2% 30.2% Example 6 80.1% 28.5% Example 7 75.7% 34.2% Example 8 76.6% 25.2% Comparative Example 1 86.8% 0% Comparative Example 2 81.5% 2.1%

Example 9 (Production of a reflective liquid crystal display device) A commercially available reflective liquid crystal display device (Color Zaurus MI-310, manufactured by Sharp Corporation)
Was peeled off, and the polarizing plate produced in Example 5 was stuck instead. About the produced reflection type liquid crystal display device, when it evaluated visually, white display, black display,
Then, it was confirmed that neutral gray was displayed without color in any of the halftones. Next, the reflection luminance was measured using a measuring machine (EZcontrast160D, manufactured by Eldim). The results are shown in Table 3.

[Example 10] (Production of reflective liquid crystal display device) A reflective liquid crystal display device was produced and evaluated in the same manner as in Example 9 except that the polarizing plate produced in Example 6 was used. The results are shown in Table 3.

[Example 11] (Production of reflective liquid crystal display device) A reflective liquid crystal display device was produced and evaluated in the same manner as in Example 9 except that the polarizing plate produced in Example 7 was used. The results are shown in Table 3.

[Example 12] (Production of reflective liquid crystal display device) A reflective liquid crystal display device was produced and evaluated in the same manner as in Example 9 except that the polarizing plate produced in Example 8 was used. The results are shown in Table 3.

Comparative Example 3 (Production of Reflective Liquid Crystal Display Device) A reflective liquid crystal display device was produced and evaluated in the same manner as in Example 9 except that the polarizing plate produced in Comparative Example 1 was used. The results are shown in Table 3.

Comparative Example 4 (Production of Reflective Liquid Crystal Display Device) A reflective liquid crystal display device was produced and evaluated in the same manner as in Example 9 except that the polarizing plate produced in Comparative Example 2 was used. The results are shown in Table 3.

[0136]

[Table 3] Table 3 ──────────────────────────────────── Reflection type liquid crystal display device Reflection luminance (Relative value) ──────────────────────────────────── Example 9 1.32 Example 10 1 .24 Example 11 1.21 Example 12 1.15 Comparative Example 3 1.00 Comparative Example 4 0.90 ────────────

As shown in Table 3, the front luminance of the liquid crystal display device according to the present invention was clearly improved as compared with the liquid crystal display device using the conventional polarizing element. The viewing angle at which the contrast ratio from the front was 20 and the contrast ratio was 3 was 120 ° or more in the vertical direction and 120 ° or more in the left and right directions.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a basic configuration of an anisotropic scattering layer.

FIG. 2 is a schematic diagram showing another basic configuration of the anisotropic scattering layer.

FIG. 3 is a schematic sectional view showing a general form of a polarizing element.

FIG. 4 is a schematic sectional view showing another general form of the polarizing element.

FIG. 5 is a schematic sectional view showing another general form of the polarizing element.

FIG. 6 is a schematic cross-sectional view showing a polarizing plate in which a light-scattering polarizing element and a light-absorbing polarizing element are combined.

FIG. 7 is a schematic cross-sectional view showing another polarizing plate in which a light-scattering polarizing element and a light-absorbing polarizing element are combined.

FIG. 8 is a schematic sectional view showing another polarizing plate in which a light-scattering polarizing element and a light-absorbing polarizing element are combined.

FIG. 9 is a schematic cross-sectional view showing still another polarizing plate in which a light-scattering polarizing element and a light-absorbing polarizing element are combined.

FIG. 10 is a schematic sectional view of a reflective liquid crystal display device including a polarizing plate.

FIG. 11 is a schematic sectional view of another reflective liquid crystal display device including a polarizing plate.

FIG. 12 is a schematic sectional view of another reflective liquid crystal display device including a polarizing plate.

FIG. 13 is a schematic cross-sectional view of yet another reflective liquid crystal display device including a polarizing plate.

FIG. 14 is a schematic sectional view of still another reflection type liquid crystal display device including a polarizing plate.

[Explanation of symbols]

 θ Angle between slow axis and scattering axis 1 Optically anisotropic discontinuous phase 2 Optically isotropic continuous phase 3, 9 Scattering axis 4, 10 Transmission axis 5, 11 Light incident direction 6, 12 Slow axis 7 Optically anisotropic continuous phase 8 Optically isotropic discontinuous phase 13 Anisotropic scattering layer 14 Transparent support 15 Light scattering type polarizing element 16 Light absorbing type polarizing layer 17, 31 Optical compensation sheet 18, 29 λ / 4 plate 19, 21 Polarizing plate 20 TN mode liquid crystal cell 22 Semi-transmissive film 23 Light guide plate 24 LED 25 Phase difference plate 26 STN mode liquid crystal cell 27 Reflecting plate 28 Cold cathode tube 30 TN mode liquid crystal cell with hole open reflector

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H049 BA02 BA04 BA25 BA26 BA27 BA42 BA44 BB03 BB13 BB43 BB47 BB49 BB51 BB63 BB67 BC03 BC09 BC14 BC22 2H091 FA08X FA10Z FA11X FA11Z FA14Y FA31Z FA41Z FD06 GA17 HA07 HA10

Claims (25)

[Claims] 1. A polarizing element having an anisotropic scattering layer that scatters one of orthogonal linearly polarized light and substantially transmits the other, wherein at least 50% of incident light having a plane of polarization parallel to the scattering axis. Is emitted to the opposite side of the incident surface, and at least 10% of the emitted scattered light is converted into elliptically polarized light or linearly polarized light having an azimuth angle of 20 degrees or more with respect to the scattering axis. 2. An anisotropic scattering layer comprising an optically isotropic continuous phase and an optically anisotropic discontinuous phase, wherein the slow axis of the optically anisotropic discontinuous phase has an orientation with respect to the transmission axis. 2. The polarizing element according to claim 1, wherein the polarizing element is inclined at an angle of 10 degrees or more with respect to the scattering axis while keeping the angle vertical. 3. An anisotropic scattering layer comprising an optically anisotropic continuous phase and an optically isotropic discontinuous phase, wherein the slow axis of the optically anisotropic continuous phase has an azimuth with respect to the transmission axis. The polarizing element according to claim 1, wherein the polarizing element is inclined to the incident side or the outgoing side by 10 degrees or more with respect to the scattering axis while maintaining the vertical direction. 4. The method according to claim 2, wherein the difference in the refractive index in the direction of the transmission axis between the optically isotropic continuous phase and the optically anisotropic discontinuous phase in the in-plane direction is less than 0.05. Polarizing element. 5. The method according to claim 2, wherein the difference in the refractive index in the scattering axis direction between the optically isotropic continuous phase and the optically anisotropic discontinuous phase is 0.03 or more in the direction in the film plane. Polarizing element. 6. The method according to claim 3, wherein the difference in the refractive index in the transmission axis direction between the optically anisotropic continuous phase and the optically isotropic discontinuous phase is less than 0.05 in the in-plane direction of the film. Polarizing element. 7. The method according to claim 3, wherein the difference in the refractive index in the scattering axis direction between the optically anisotropic continuous phase and the optically isotropic discontinuous phase is 0.03 or more in the in-plane direction of the film. Polarizing element. 8. The polarizing element according to claim 2, wherein the optically isotropic continuous phase comprises a polymer compound. 9. The polarizing element according to claim 2, wherein the optically anisotropic discontinuous phase has an average diameter of an approximate circle of 0.01 to 10 μm. 10. The polarizing element according to claim 3, wherein the optically isotropic discontinuous phase has an average diameter of an approximate circle of 0.01 to 10 μm. 11. The polarizing element according to claim 2, wherein the optically anisotropic discontinuous phase contains a liquid crystalline compound. 12. The polarizing element according to claim 3, wherein the optically anisotropic continuous phase contains a liquid crystalline compound. 13. The polarizing element according to claim 11, wherein the liquid crystal compound has a polymerizable group. 14. The polarizing element according to claim 11, wherein the liquid crystalline compound has a smectic C phase. 15. A light-absorbing polarizing element having an anisotropic scattering layer that absorbs one of orthogonal linearly polarized light and substantially transmits the other, and scatters one of orthogonal linearly polarized light and substantially converts the other. A light-scattering polarizing element having an anisotropic scattering layer that transmits light is disposed such that the polarization transmission axis of the light-absorbing polarization element and the polarization transmission axis of the light-scattering polarization selection element are substantially parallel to each other. At least 50% of incident light having a plane of polarization parallel to the scattering axis of the light-scattering polarization selection element.
Is emitted to the opposite side of the incident surface, and at least 10% of the emitted scattered light is converted into elliptically polarized light or linearly polarized light having an azimuth angle of 20 degrees or more with respect to the scattering axis. 16. The polarizing plate according to claim 15, wherein the degree of polarization of the light-absorbing polarizing element is 99% or more. 17. The polarizing plate according to claim 15, which has at least one transparent support. 18. The polarizing plate according to claim 17, wherein the transparent support comprises a cellulose triacetate film. 19. The polarizing plate according to claim 18, wherein the transparent support is a cellulose triacetate film manufactured without using methylene chloride. 20. An optically anisotropic layer formed from discotic liquid crystalline molecules, wherein the optically anisotropic layer, the light absorbing polarizing element, and the light scattering polarizing element are laminated in this order. The polarizing plate according to claim 15. 21. A reflection type liquid crystal display device comprising a reflection plate, a liquid crystal cell, a λ / 4 plate and a polarizing plate laminated in this order, wherein the polarizing plate absorbs one of a transparent support and orthogonal linearly polarized light. A light-absorbing polarizing element having an anisotropic scattering layer that substantially transmits the other, and a light-scattering polarized light having an anisotropic scattering layer that scatters one of orthogonal linearly polarized light and substantially transmits the other. The light-absorbing polarizing element is disposed so that the polarization transmission axis of the light-absorbing polarization element is substantially parallel to the polarization transmission axis of the light-scattering polarization selection element. At least 50% of the incident light having a plane of polarization parallel to the axis exits on the opposite side of the plane of incidence, and at least 10% of the emitted scattered light becomes elliptically polarized light or linearly polarized light having an azimuth angle of 20 degrees or more with the scattering axis. Reflective liquid crystal display characterized by being converted Location. 22. A reflection type liquid crystal display device in which a reflection plate, a liquid crystal cell and a polarizing plate are laminated in this order, wherein the polarizing plate absorbs one of a λ / 4 plate and orthogonal linearly polarized light, and the other absorbs one. A laminate of a light-absorbing polarizing element having a substantially transmitting anisotropic scattering layer and a light-scattering polarizing element having an anisotropic scattering layer which scatters one of orthogonal linearly polarized light and substantially transmits the other. Are arranged so that the polarization transmission axis of the light absorption type polarization element and the polarization transmission axis of the light scattering type polarization selection element are substantially parallel to each other, and are parallel to the scattering axis of the light scattering type polarization selection element. At least 50% of the incident light having a plane of polarization
Is emitted to the opposite side of the incident surface, and at least 10% of the emitted scattered light is converted into elliptically polarized light or linearly polarized light having an azimuth angle of 20 degrees or more with respect to the scattering axis. 23. A liquid crystal display device comprising a backlight, a polarizing plate, a liquid crystal cell of a twisted nematic alignment mode, and a polarizing film laminated in this order, wherein the polarizing plate on the backlight side is arranged in order from the liquid crystal cell side. An optically anisotropic layer formed from discotic liquid crystalline molecules, an optically anisotropic transparent support, and an optically anisotropic scattering layer that absorbs one of orthogonal linearly polarized light and substantially transmits the other. Type polarizing element, and a laminate of light scattering type polarizing elements having an anisotropic scattering layer that scatters one of orthogonal linearly polarized light and substantially transmits the other, and has a discotic liquid crystal molecule disc surface. The angle between the average direction of normal projection of the normal onto the optically anisotropic transparent support and the in-plane slow axis of the optically anisotropic transparent support is substantially parallel or perpendicular; In-plane slow axis and light absorption in the body The polarization transmission axis of the polarizing element is substantially parallel or perpendicular, and furthermore, the polarization transmission axis of the light-absorbing polarization element and the polarization transmission axis of the light-scattering polarization element are arranged so as to be substantially parallel. And at least 5 of incident light having a plane of polarization parallel to the scattering axis of the light-scattering polarization selection element.
A twisted nematic alignment mode characterized in that 0% is emitted to the side opposite to the incident surface, and at least 10% of the emitted scattered light is converted into elliptically polarized light or linearly polarized light having an azimuth angle of 20 degrees or more with respect to the scattering axis. Liquid crystal display device. 24. A liquid crystal display device comprising a backlight, a polarizing plate, a bend alignment mode liquid crystal cell, and a polarizing plate laminated in this order, wherein the polarizing plate on the backlight side comprises:
In order from the liquid crystal cell side, an optically anisotropic layer formed from discotic liquid crystalline molecules, an optically anisotropic transparent support, and anisotropic scattering that absorbs one of orthogonal linearly polarized light and substantially transmits the other A light-absorbing polarizing element having a layer, and a laminate of a light-scattering polarizing element having an anisotropic scattering layer that scatters one of orthogonal linearly polarized light and substantially transmits the other. The angle between the average direction of the orthogonal projection of the normal of the molecule disk surface onto the optically anisotropic transparent support and the in-plane slow axis of the optically anisotropic transparent support is substantially 45 degrees, The in-plane slow axis of the isotropic transparent support and the polarization transmission axis of the light-absorbing polarizing element are substantially parallel or perpendicular,
Further, the polarization transmission axis of the light absorption type polarization element and the polarization transmission axis of the light scattering type polarization element are arranged so as to be substantially parallel, and have a polarization plane parallel to the scattering axis of the light scattering type polarization selection element. At least 50% of the incident light is emitted to the opposite side of the incident surface, and at least 10% of the emitted scattered light is converted into elliptically polarized light or linearly polarized light having an azimuth angle of 20 degrees or more with respect to the scattering axis. Liquid crystal display device of bend alignment mode. 25. A liquid crystal display device in which a backlight, a polarizing plate, a liquid crystal cell in a horizontal alignment mode, and a polarizing plate are stacked in this order, wherein the polarizing plate on the backlight side is arranged in order from the liquid crystal cell side. Optical absorption type having an optically anisotropic layer formed from discotic liquid crystalline molecules, an optically anisotropic transparent support, and an anisotropic scattering layer that absorbs one of orthogonal linearly polarized light and substantially transmits the other A polarizing element, and a laminate of light-scattering polarizing elements having an anisotropic scattering layer that scatters one of orthogonal linearly polarized light and substantially transmits the other, and uses a discotic liquid crystal molecule disc method. The angle between the average direction of orthogonal projection of the line onto the optically anisotropic transparent support and the in-plane slow axis of the optically anisotropic transparent support is substantially 45 degrees, The in-plane slow axis and the polarization transmission axis of the light-absorbing polarizer are Qualitatively parallel or vertical,
Further, the polarization transmission axis of the light absorption type polarization element and the polarization transmission axis of the light scattering type polarization element are arranged so as to be substantially parallel, and have a polarization plane parallel to the scattering axis of the light scattering type polarization selection element. At least 50% of the incident light is emitted to the opposite side of the incident surface, and at least 10% of the emitted scattered light is converted into elliptically polarized light or linearly polarized light having an azimuth angle of 20 degrees or more with respect to the scattering axis. Liquid crystal display device of horizontal alignment mode.