TW200827857A - Transparent film, polarizing plate and liquid crystal display device - Google Patents

Abstract

The purpose of the present invention is to provide a novel transparent film which contributes reduction in both wavelength dependence and wide viewing angle dependence. The transparent film comprises a region where Nz values in the normal line direction of the film are monotoneous increase or decrease in the range of 0 to 1 and has an in-plane retardation (Re) of 510 to 610 nm. But, Nz =0.5+Rth(550)/Re(550), wherein Rth(550) and Re(550) represent the retardation in the thickness direction and the in-plane retardation respectively.

Description

[Technical Field] The present invention relates to a novel transparent film which can be used as a protective film of an optical compensation light plate of a liquid crystal display device, and a polarizing plate and a liquid crystal display device using the same. [Prior Art] A transmissive liquid crystal display device has a liquid crystal cell and two polarizers (Polarizers). The arrangement of the pair of polarizers is generally orthogonal to the axis, i.e., a so-called orthogonal polarizer. However, the orthogonal polarizer can function as a polarizer for the light incident on the normal direction of the surface, but for oblique light from the normal direction, since the crossing angle of the transmission axis deviates from the right angle, the polarizer cannot be used. Function. This causes light leakage to occur in the transmissive liquid crystal display device, which is dependent on a decrease in the contrast of the viewing angle and a decrease in the hue angle characteristics. However, a polarizing mirror composed of a polyvinyl alcohol film or the like, a separate member is used for the liquid crystal display device, but a protective film of a S-polarized mirror is attached to both sides thereof to be used as a polarizing plate to penetrate the liquid crystal display. The protective film is provided with a specified optical field of view. As an example of this, there is a proposal that "a wide-field sound is made up of a biaxial phase difference plate having a birefringence characteristic in which an in-plane retardation = 250 Νζ = 〇 · 1 to 0.4 is superimposed on a polarizer. a viewing angle polarizing plate which is formed by superposing a pair of two films having a birefringence characteristic of difference = 250 to 300 nm and Nz = 0.6 to 1.1 on the polarizing mirror, and a pair of translucent film sides. Orthogonally incident as orthogonal, inclined square change, etc. are not used together to protect the device. Sex, and wide _ polarizing plate, -300 nm, :", and Γ an 'in-plane phase 1 axis phase 200827857 The difference is made" (Patent Document 1). In the embodiment of Patent Document 1, it is shown that two of the wide viewing angle polarizing plates are arranged on both sides of the liquid crystal cell in an orthogonal arrangement, and the resulting transmissive liquid crystal display device has a wide viewing angle. In the wide viewing angle technique of the polarizing plate described in Patent Document 1, the incident light must pass through the biaxial phase difference plate having the specified birefringence twice. Therefore, the liquid crystal display device is limited in design, or requires complicated control of the positional relationship between the optical axes of the phase difference plates of the specified optical characteristics, and is complicated by two layers, from the viewpoint of productivity. good. Φ On the other hand, although it is attempted to pass the incident light only through one phase difference plate, the viewing angle dependence of the polarizer is compensated, but in this case, the problem of wavelength dependence occurs. This is because the hysteresis of a triacetyl cellulose film or the like which is generally used as a protective film for a polarizing plate shows wavelength dependence. For example, even if the incident light having a central wavelength of 550 nm (G) in the visible light wavelength range of 400 to 70 Onm is converted into an extinction point by the protective film, the optical characteristics of the protective film are adjusted, but it is 45 0 nm ( B) and 65 0 nm (R) of incident light are converted into a polarized state that deviates from the extinction point, and as a result, a hue change or a decrease in contrast depending on the viewing angle occurs. [Patent Document 1] JP-A No. 200 1 - 350022 [Invention] The present invention has been made in view of the above problems. In order to solve the above problems, the present invention provides a wide frequency band that can correspond to the entire visible light range. A novel polarizer with a wide viewing angle. Further, an object of the present invention is to provide a novel transparent film which is used as a protective film for the 200827857 light plate and as an optical compensation film for a liquid crystal display device, which contributes to both wavelength dependence and viewing angle dependence. Further, an object of the present invention is to provide a liquid crystal display device which is capable of reducing a decrease in contrast and a change in color tone depending on a viewing angle, and having a good viewing angle characteristic. Means to solve the problem The means to solve the above problems are as follows. [1] A transparent film comprising a region in which the Nz値 monotonously increases or monotonically decreases in the normal direction of the film surface, and the in-plane retardation 値Re of a wavelength of 5 5 〇nm is 510 to 610 nm; but Nz = 0.5 + Rth(5 50)/Re(5 50), where Rth(5 50) and Re(5 5 0) are each a hysteresis 面 and an in-plane hysteresis 厚度 in the thickness direction of a wavelength of 5 5 Onm. [2] A transparent film such as [1] which contains deuterated cellulose as a main component. [3] A transparent film such as [1] which contains a polymer resin having an alicyclic structure as a main component. [4] A transparent film characterized in that it has optical anisotropy in the plane, and a circular hysteresis (CRE1) in the normal direction of the film surface is about 〇, at a polar angle of 60 degrees from the normal direction of the film surface. The absolute value of the circular hysteresis (CRE2) of the light incident in the four directions of the azimuth angles of 45 degrees, 135 degrees, 225 degrees, and 315 degrees is taken as the azimuth angle of 0 degrees in the film plane. The lines are roughly equal and not zero. [5] The transparent film according to [4], wherein the above CRE2 is 0 to 20 nm. [6] The transparent film ' in [1] has a multilayer structure in which two or more layers different in Nz 値 are different from each other. [7] The transparent film according to [6], which has at least one of a polymer film and an optically anisotropic layer each of which is composed of the same or different liquid crystal compositions on both sides of 200827857. [8] A polarizing plate having a polarizing film and a transparent film according to any one of [1] to [7]. [9] A liquid crystal display device comprising a liquid crystal cell and a polarizing plate such as [8]. [1 〇] A liquid crystal display device having a liquid crystal cell and at least one polarizing film, wherein the polarizing film and the liquid crystal cell have any one of [1] to [7] Transparent film. EFFECT OF THE INVENTION According to the present invention, a novel polarizing plate having a wide frequency band and a wide viewing angle can be provided. Further, according to the present invention, a novel transparent film which serves as a protective film for the polarizing plate and which serves as an optical compensation film for a liquid crystal display device contributes to reduction in both wavelength dependency and viewing angle dependence. Further, according to the present invention, it is possible to provide a liquid crystal display device which is capable of reducing the contrast reduction and the color shift change depending on the viewing angle. [Embodiment] The present invention will be described in detail below. In the present specification, "~" is used to mean that the number described before and after is used as the lower limit 値 and the upper limit 値. The invention is described below. In the present specification, "~" is used in the sense that the number recited before and after is used as the lower limit 値 and the upper limit 値. And 'substantially orthogonal or parallel system means a strict angle: bio. The scope. In addition, in the present specification, & (λ) and Rth (X) each indicate a hysteresis 面 in the plane at the wavelength λ and a hysteresis 厚度 in the thickness direction. In the KOBRA 2 1 ADH or WR (manufactured by Oji Scientific Instruments Co., Ltd.), the light of the wavelength ληπι is incident on the normal direction of the film. When the film to be measured is represented by a refractive index ellipsoid of one axis or two axes, RthQ) is calculated by the following method.

Rth(X) is used as the tilt axis (rotary axis) with the above-mentioned Re(X) and the in-plane slow axis (determined by KOBRA 21 ADH or WR) (when there is no slow phase axis, it is arbitrary in the film plane) The direction is regarded as the rotation axis), and the light of the wavelength ληιη is incident from the direction of the inclination of each of the oblique directions from the normal direction of the normal direction of the film to the side of 50 degrees. It is calculated by KOBRA 21ADH or WR based on the measured hysteresis 値 and the assumed 値 of the average refractive index and the input film thickness 値. In the above, in the case where the in-plane slow axis in the normal direction is regarded as the rotation axis, and the film having the hysteresis 値 in the direction of zero at a certain inclination angle, the retardation of the inclination angle larger than the inclination angle 値After the sign is changed to negative, it is calculated by KOBRA2 1ADH or WR. In addition, the slow phase axis is used as the tilt axis (rotary axis) (when there is no slow phase axis, the arbitrary direction in the film plane is regarded as the rotary axis), and the hysteresis is measured from two directions of arbitrary tilt, and the hysteresis is measured. Based on the assumption of the average refractive index and the film thickness 输入 input, Rth can also be calculated by the following formulas (21) and (22). l{nysm(sin ))2 {π2 cos(sin ^ sin (-^) cos {sin (--)} nx - (2 1) 200827857

Rth={(nx + ny)/2-nz}xd - Equation (22) where Re(e) represents the hysteresis 方向 in the direction inclined from the normal direction by the angle θ. Further, in the formula, η χ represents the refractive index in the direction of the slow axis in the plane, ny represents the refractive index in the direction orthogonal to nx in the plane, nz represents the refractive index in the direction orthogonal to η χ and ny, and d represents the film thickness. . The film to be measured cannot be represented by a one-axis or two-axis refractive index ellipsoid, that is, in the case of a film having no optic axis, RthQ is calculated by the following method.

Rth〇) is the above-mentioned Re(X), the in-plane slow phase axis (determined by K0BRA 2 1 AD Η or WR) as the tilt axis (rotary axis), from -50 to the normal direction of the film. When the degree is up to +50 degrees, the light of the wavelength ληηι is incident from each oblique direction at a 1 degree degree and measured at 1 point, and the measured hysteresis 値 and the average refractive index are assumed and the input film is measured. Based on thick enamel, it is calculated by KOBRA 21ADH or WR. Further, in the above measurement, the assumption of the average refractive index may be a polymer handbook (JOHN WILEY & SONS), and a catalogue of various optical films. In the case where the average refractive index is not known, an Abbe refractometer can be used for the measurement. The average refractive index of the main optical film is exemplified below: deuterated cellulose (1.48), cycloolefin polymer (1.5 2), polycarbonate (1.5 9), polymethyl methacrylate (1.49), polystyrene (1.59). KOBRA 21 ADH or WR calculates nx, ny, and nz by inputting the assumption of the average refractive index and the film thickness. Nz = (nx - nz) / (nx - ny) is calculated from the calculated nx, ny, and nz. Further, in the present specification, the numerical range or the numerical range indicating the optical characteristics and the like can be interpreted as a range of the number or range of errors generally accepted in the liquid crystal display device or the member used therefor. The present invention relates to a transparent film comprising a region in which the Nz 値 in the normal direction of the film surface monotonously increases or monotonically decreases from 0 to 1, and the in-plane retardation 値Re of a wavelength of 50 nm is 5 1 0 to 6 1 Onm. The transparent film of the present invention is disposed between the polarizer and the liquid crystal cell by being combined with the polarizer, and contributes to a reduction in contrast reduction and color tone change of the tilt direction of the liquid crystal display device. Furthermore, "About the area where the normal direction of the film surface (the thickness direction of the film) is monotonically increasing or monotonically decreasing in the range of 0 to 1" can be referred to by the literature: Y. Takahashi, H. Watanabe and T Kato5 u Depth-Dependent Determination of Molecular Orientation for WV-Film,,, ID W'04 (2 0 04), page 651 to confirm. Specifically, the X, y, and z components of P 2 which are equal to five points in the thickness direction of the film are measured, and Nz obtained by using nx, ny, and nz calculated therefrom is used in the range of 0 to 1. The internal variation, for example, for each of the five points, means that Nz値 varies in the manner of large 〇, 〇·25, 0.5, 0·75, and 1. In addition, as for the "monotonous increase and monotonous decrease" of the Nz of the film, the increase rate and the decrease rate may vary, and there is no range of increase or decrease, but there is no minimum decrease range in the monotonous increase, and there is no monotonous decrease. The smallest increase in the range. The preferred rate of increase is a fixed monotonic increase, or a reduction in the rate of a fixed monotonic decrease. As one aspect of the transparent film of the present invention, a transparent film having a multilayer structure in which N z 値 is two or more layers different from each other is exemplified. More specifically, having a polymer film, and each of its faces is identical by -1 1 -

V 200827857 or at least one layer of each of the optically anisotropic layers composed of different liquid crystal compositions, the Nz of one of the optically anisotropic layers is 0, the Nz of the polymer film is 0.5, and the other optically isotropic layer A transparent film having a Nz of 1.0 is also an aspect of the present invention. If a plurality of optically anisotropic layers in which Nz are different from each other are formed on one surface of the polymer film, and/or a multilayer structure in which the Nz is a polymer film different from each other for the supported polymer film, A transparent film in which Nz is monotonously increased (or monotonically decreased) at a small rate of change in the range of 0 to 1 is produced. ® Fig. 1 shows an example of a polarizing plate having a transparent film of the present invention. The polarizing plate 10 of Fig. 1 has a polarizing mirror 12 made of a polyvinyl alcohol (PVA) film dyed with iodine or the like, and a protective film 14 and 1 formed of a deuterated cellulose film or the like on the surface thereof. 6. The protective film 16 is a transparent film of the present invention and satisfies the optical characteristics specified above. When the polarizing plate 1 is inserted into the liquid crystal display device, the liquid crystal cell is sandwiched together with the other polarizing plate, and the transparent film of the present invention, that is, the protective film 16 is used as the liquid crystal cell side, so that the polarizing plates are mutually absorbed. Configured orthogonally. Further, the transparent film of the present invention is not necessarily used as a protective film for a polarizer to directly adhere to the surface of the polarizer. For example, the transparent film of the present invention can also be disposed as an optical compensation film between the polarizer and the liquid crystal cell. When a protective film of a polarizer is disposed between the polarizing mirror and the transparent film of the present invention, the protective film is preferably an isotropic film having no phase difference. Next, the effect of the transparent film and the polarizing plate of the present invention will be described with reference to the drawings. Fig. 2 to Fig. 5 are diagrams showing a poincare ball from the positive direction of the S2 axis. The Poincaré ball system describes the three-dimensional land of the polarized state. -12- 200827857 The eccentricity of the ball indicates the polarized state of the linear polarized light with an ellipticity of zero. The point 第 in Fig. 2 indicates that the light incident from the oblique direction is linearly polarized by the polarizing mirror, and its light is in a polarized state. If the polarization state point Ρ is converted to the polarization state point Q of the extinction point on the s 1 axis, the viewing angle dependency of the orthogonal polarizer is eliminated. Therefore, by changing the polarization state from the point 成 to the point Q by the protective film disposed on the liquid crystal cell side of the polarizer, the birefringence of the protective film can be adjusted by the change in the polarization state caused by the phase difference region. The Poincaré ball is rotated on a specific axis depending on the optical characteristics, and is represented by a specific angle of rotation. As an example of the polarization state point Ρ being converted into the polarization state point Q, as shown in Fig. 3, a 1/2 wave plate as a protective film is used, and the S2 axis is used as a rotation axis, and is converted by only π rotation. Furthermore, the angle of rotation is proportional to the phase difference of the phase difference region passing through and is proportional to the reciprocal of the wavelength of the incident light. However, most of the refractive index (η) of a film used as a protective film such as a deuterated cellulose film is different for the wavelength of incident light, and generally the longer the wavelength is, the smaller the tendency is. In terms of phase difference, the longer the wavelength of the incident light, the smaller the wavelength dependence. Due to the influence of the wavelength dependence of the refractive index, and the above-described rotation angle is proportional to the reciprocal of λ, the transition of the polarization state displayed on the Poincare sphere is the longer the wavelength of the light, and the smaller the rotation angle. Therefore, it is difficult to convert the R light (65 0 nm), the G light (550 nm), and the neon light (450 nm) into the polarization state shown in FIG. 3 by one phase difference plate, for example, As for the G-light at the center wavelength (5 5 Onm), even if a protective film that can be switched to the extinction point is used, as shown in Fig. 4, the R light and the B light are shifted from the extinction point. Therefore, in the present invention, instead of the conversion of the birefringence polarization state of the film, as shown in Fig. 3, the birefringence and the optical rotation of the film are used, and the polarization state is switched to reduce The above wavelength dependence. The transparent film of the present invention comprises a region in which the N z 单 in the normal direction of the film surface monotonously increases or monotonously decreases in 〇 〜1. This region is, for example, a laminate in which a layer having a very small film thickness is laminated only in an infinite number, and can be approximated as a laminate having a very small increase or decrease in the adjacent layers Nz. If Nz = 1 on the most surface layer on the incident side and Νζ = 0 on the outermost layer on the exit side, indicating the transition of the polarization state of the light incident on the virtual laminate, the linear polarization of the first layer LNz = 受到 is received. The influence of the birefringence of the layer, the trajectory of the transition at this time means that the axis parallel to the S2 axis of the point P is rotated as a rotary axis. Since the Nz is slightly reduced in the second layer, the rotary axis is an axis which is parallel to the S2 axis from the point P on the S 1 axis and which is slightly shifted in the direction of S 1 = 0. In the third and fourth layers, the Nz system is reduced, and the rotary axis moves in the direction of S 1 = 0. In the layer LNz = 0.5 with Nz = 0.5, the rotary axis becomes the S2 axis. Finally, in the outermost layer Lnz^ on the exit side, the rotary axis becomes an axis parallel to the S2 axis of the extinction point Q.

The transition trajectory of the polarization state therebetween is approximately ΔΝζ-0 when the increase or decrease ΔΝζ of the adjacent Nz between the layers is as shown in Fig. 5. The transition trajectory of the polarization state shown in Fig. 5 is indicated by a broken line in Fig. 5, and the so-called optical rotation rolling cone has a center line side from a point on the S 1 axis to a direction of S 1 =0, and then Moving in a negative direction, making a turn to reach the extinction point Q, along the same trajectory. Although the wavelength dispersion of the refractive index is also affected by the rotation of the rolling cone indicating the optical rotation, it is compared with the rotation using only the birefringence shown in Fig. 4, and reaches the extinction point in the polarized state. Q -14 - 200827857 When the separation of the R light, the G light, and the B light is small, the wavelength dispersion property can be alleviated. Further, the Re of the transparent film (the sum of the in-plane retardation 値) is taken as the amount of movement on the Poincare sphere, so that the rolling cone is 3 60. It is necessary for the rotation system to be around 560 nm. Actually, it is effective for the conventional example in the range of 510 to 610 nm. i When the transparent film of the present invention is expressed from another point of view, although the optical properties of the incident light in the normal direction of the film do not occur, an optically active film is generated for the incident light in the oblique direction. which performed. More specifically, the transparent film of the present invention, from another point of view, can have a circular hysteresis (CRE1) of about 0 for light incident from the normal direction of the film surface, for a pair of films. The absolute enthalpy of (CRE2) measured by the incident light in the oblique direction of the complex numbers different from each other is substantially equal, and is not expressed as a special transparent film. Here, the oblique direction of the plurality of mutually different film faces can be defined, for example, as a polar angle of 60 degrees from the normal direction of the film face, and when the azimuth axis in the film face is taken as an azimuth angle of 0 degrees. The azimuth angles are 4^ directions of 45 degrees, 135 degrees, 225 degrees, and 315 degrees. Here, the absolute 値 of the CRE2 when incident from the four directions is not satisfied in the film which is simply twisted in the direction of the slow axis, and the film is significantly different from the transparent film of the present invention. In the transparent film of the present invention, the Nz system has a different distribution in the thickness direction, and as a result, the azimuth angle is 45 degrees, 135 degrees, 225 degrees, and 3 when the late phase axis of the film is used as the azimuth angle. Although the symbols in the four directions of 1 5 degrees are different, they are absolutely equal. For the light incident from the above four directions, the absolute enthalpy of 'CRE2' is preferably 32 to 38 nm. Furthermore, the so-called roughly equal means that the difference between -15-200827857 is the same or 値 is below 5 nm. The CRE (CRE1 and CRE2)' of the film can be measured, for example, by Axometrics' Mueller Matrix Polarimeter "AxoScan". Further, the details of CRE are described in the literature: S. Y. Lu and R. A. Chipman, J. Opt Soc. Am A. 1 3 (1 996) 1 1 06·. The raw material of the transparent film of the present invention is not particularly limited. For example, even if the birefringent polymer film is stretched, an optically anisotropic layer formed by fixing a liquid crystal compound in a specific alignment state may be used. Further, the transparent film is not limited to a single layer structure, and may have a multilayer structure having a plurality of layers. In the multi-layered construction, the materials of the layers may be of the same type or different types. For example, it may be a laminate of an optically anisotropic layer composed of a polymer film and a liquid crystal composition. In the aspect of the multilayer structure, in consideration of the thickness, a multilayer system containing a coating layer of a layer formed by coating is preferable as compared with a laminate of a polymer stretched film. By selecting the raw materials used, the blending amount, the production conditions, and the like, and adjusting the enthalpy within the desired range, a transparent film having Nz 値 satisfying the above conditions can be produced. Specifically, it is possible to: mix two or more types of polymers having different wavelengths (for example, a plurality of polymers having different absorption wavelengths in the main chain direction); and add an additive having absorption in the ultraviolet region or the infrared region to control Dispersion of wavelength of visible light; an additive that absorbs in the ultraviolet region or the infrared region, that is, an alignment in the thickness direction, the stretching direction, or the non-stretching direction of the film, is added to the film; by coating or laminating a multilayer body that becomes a polymer layer (for example, a multilayer body of polymer layers having different birefringences); controlled by imparting a non-uniform temperature distribution in the thickness direction in the film process - 16 - 200827857 or ultraviolet intensity distribution ' Orientation or uniformity of the material; etc. to make the transparent film of the present invention. The material used in the production of the transparent film of the present invention is not particularly limited, and it is preferred to use a polymerized resin (original borneene-based polymer, etc.) having deuterated cellulose and an alicyclic structure as a main component. Ingredients. Further, the present invention also relates to a polarizing plate having the transparent film of the present invention. The polarizing plate of the present invention is preferably a protective film which is used as one side of the polarizing mirror, i.e., adheres to the transparent film of the present invention to contact the surface of the polarizer. When the polarizing plate of the present invention is incorporated into a liquid crystal display device, it is preferred to arrange the transparent film of the present invention on the liquid crystal cell side. The characteristics of the polarizing plate can be described by a dichroic (double-tuning) vector D or a polarizing power (polarization) vector P. The so-called dichroic (double-tuning) vector D, on the Poincare sphere, indicates the polarization state in which the amount of transmitted light becomes maximum, and the so-called polarization ability (polarization) vector P, on the Poincare sphere, indicates that there will be no polarization. The exiting polarization state at the time of incidence. The vector represented by the dichroic vector 〇 = (011, 045, 0 〇, polarizing power vector 1 > = (?11, ?45, P〇. If using the Dua Bo Rotate" Retarder mode polarizer as the measurement It is preferable to measure the D and P of the laminate of the polarizing film and the birefringent polymer film. The polarizer and the measuring head of the Dual · Rotate · Retarder method include polarized light for making a polarized wave. Both the generator and the polarizing analyzer for detecting the polarization wave are polarized measuring instruments made up of a high-speed rotating wavelength plate and a polarizing mirror. As a commercial product, Axometrics Mueller Matrix Polarimeter can be used. -17 - 200827857 In addition, the dichroism vector and the polarization vector are each made into a unit vectorization, and the specifications 1 D' = (Dh', D45', Dr') and the normalized polarization vector are also available. F Pr') is described. For details of this, in Y. Ootani p · 2 0 (2 0 0 7)) & SY.LuandR.A.Chipman:

It is described in Am. A 13 p.ll 06 (1996)). In the polarizing plate of the present invention, the absolute 値|P45'| of P45' is shown by P ′ to exhibit a viewing angle of 0.9 or more, preferably 0.99. The transparent film or polarizing plate of the present invention can be used in various display devices. For example, it can be used in various modes of liquid crystal display devices such as IPS mode, VA mode, and mode. Regarding some examples of the transparent film of the present invention, the results of the effects are confirmed below. Vector size gauge Seven dichroism vector ~ (Ph,, P45,, :Ο plus E 29 J. Opt. S o c . , is a polarizing plate of the above degree of wide mode liquid crystal display TN mode, OCB table shows the actual

-18- 200827857 [Table 1] Nz in-plane retardation 四 (4) CRE1 (nm) CRE2 (nm) absolute 値 @ azimuth angle 45 degrees CRE2 (nm) absolute 値 @ azimuth angle 135 degrees CRE2 (nm) absolute 値 @ Aperture angle 225 degrees CRE2 (nm) Absolute 値 @ azimuth 315 degrees 黒 state transmittance (%) Comparative example 5.5 (thickness in the thickness direction) 275 0 0 0 0 0 0.034 Example 1 in the thickness direction 〇~1 Change 510 0 38 38 38 38 0.031 Example 2 Change in thickness direction from 〇 to 1 550 0 35 35 35 35 0.021 Example 3 Change in thickness direction from 〇 to 1 560 0 35 35 35 35 0.021 Example 4 In the thickness direction at 0~ 1 change 570 0 35 35 35 35 0.021 Example 5 Change in thickness direction from 〇 to 1 600 0 35 35 35 35 0.026 me Change in thickness direction from 〇 to 1 610 0 32 32 32 32 0.028 Comparative example film thickness direction A uniform film having a Nz 値 of 0.5 ·, which is an example for comparison with the present invention. Examples 1 to 6 are films in which the Nz 变化 varies in the thickness direction from 0 to 1, and the in-plane retardation 値Re satisfies 510 to 6 1 Onm, which is an example of the transparent film of the present invention. Further, it can be understood from the numbers in the table that in all of Examples 1 to 6, CRE 1 is 0, and CRE2 measured for incident light from four directions is not 0 and is equal. In comparison with the comparative examples, it can be understood that the transmittances (%) of the examples 1 to 6 are all in the black state, and the contrast is improved. Similarly, in the state in which the polarizing film is laminated on the transparent film, that is, in the form of the polarizing plate, when the polar angle is 60 degrees from the normal direction of the film surface, and the azimuth angle in the film surface is taken as the azimuth angle, The light is incident in a direction in which the azimuth angle is 45 degrees, and the transparent film is placed on the exit side of the polarizing film, and the normalized polarization ability vector P' = (Ph', P45', Pr') is measured. Since P' is a unit vector, the maximum 値 of the magnitude of the vector is also considered to be 1, and the absolute 値| P45 of the P4 5' of the polarizing plate of Examples 1 to 6 is 0.99 or more and less than 1. -19- 200827857 [Table 2]

Nz jPh,| |P455I |Pr, transmittance in black state (%) Comparative example 0.5 (thickness in thickness direction) 0.108 0.994 0.000 ^ 0.034 Example 1 Change in thickness direction 〇~1 0.138 0.990 0.006 0.031 Example 2 In the thickness direction Change in 0~1 0.107 0.994 0.000 0.021 Example 3 Change in thickness direction 〇~1 0.099 0.995 0.001 0.021 Example 4 Change in thickness direction 〇~1 0.093 0.996 0.002 0.021 Example 5 Change in thickness direction 〇~1 0.075 0.997 0.010 A case of the IPS mode liquid crystal display device of the IPS mode is confirmed to be effective in the actual production of the transparent film and the polarizing plate as described below. An embodiment. However, the invention is not limited by the following examples. [Comparative Example 1] <Production of Film 1> A size change of 1 65 degrees was adhered via an acrylic adhesive layer on both sides of a polycarbonate having a length of 10 mm, a width of 180 mm, and a thickness of ΙΙΟμπι Re of Onm. A polyester film having a ratio (MD/TD) of 1.15, which is treated under the conditions of a roll speed of a roll speed of 0.97 and a normal temperature of 165 degrees at a roll temperature to shrink the polycarbonate. Peel the polyester film. This film was stretched by 1.1 times in the width direction under an atmosphere of a temperature of 1 to 63 ° to obtain a film 1. The optical incident angle dependence of Re was measured using an automatic birefringence meter (K0BRA-21ADH, manufactured by Oji Scientific Instruments Co., Ltd.), and the optical characteristics were calculated. As a result, it was confirmed that R e was 2 7 5 nm, and N z was 0.5, the slow phase axis is in a direction orthogonal to the length -20-200827857 degrees. For the film 1, AxScan of Ax0metrics was used to measure CR1 of the front side of the wavelength of 550 nm, and the azimuth angle of 45 degrees, 135 degrees, 225 degrees, and 3 15 degrees of the CR2 of the polar angle of 60°, and the CR1 and the CR2 of all azimuth angles were obtained. All are Onm. <Preparation of polarizing plate 1 for comparative example> A roll-shaped polyvinyl alcohol film having a thickness of 80 μm was continuously stretched five times in an aqueous iodine solution, and dried to obtain a polarizing film. For the polyvinyl alcohol, PVA-11 7® manufactured by Kuraray was used. The film for the comparative example was laminated on one surface of the polarizing film. 1. The Fujifilm Co., Ltd. was used as a protective film on the other side.

Tackfilm TD8 0U, a polarizing plate 1 for comparative use was produced. The normalized polarization ability vector P' of the polarizing plate 1 for this comparative example was measured by Axo scan. When the polar angle of the normal direction of the film surface is 60 degrees, and the azimuth angle is 0 degree in the film surface, the light is incident in the direction of the azimuth angle of 45 degrees, so that the film 1 of the comparative example is located. The absolute side of the normalized polarizing ability vector P' was found to be 0.994 on the exit side of the polarizing film. [Example 1] ® <Preparation of Transparent Film 10> An optically anisotropic layer 1 was formed on one surface of the film 1 produced in Comparative Example 1 by the following method, and an optically anisotropic layer was formed on the other surface. 2, to produce a transparent film 10 of an embodiment of the present invention. &lt;Formation of optically anisotropic layer 1 composed of a rod-like liquid crystal composition&gt; (Formation of alignment film) An alignment film coating liquid having the following composition was prepared. -21 - 200827857 The following polymer compound P 4 parts by mass of triethylamine. 2 parts by mass of D ec ο na 1 EX - 5 2 1 5% aqueous solution (epoxy compound of NAGASE Chemical Industry Co., Ltd.) 8.1 parts by mass of water 57 parts by mass of methanol 29 parts by mass

Polymer Compound P 4-CH2CH)^r4CH2CH^~~(-CH2CH^

The alignment film coating liquid was applied to one surface of the film 1, and dried at 120 ° C for 120 seconds at 25 ° C for 30 seconds. The thickness of the alignment film after drying was 1. 5 μm. Next, the formed film was subjected to a rubbing treatment in the same direction as the longitudinal direction of the transparent film 1. (Formation of Optically Isotropic Layer 1) A coating liquid for an optically anisotropic layer having the following composition was prepared. The following rod-like liquid crystal compound (exemplified compound IV-2) 38.1% by mass The following sensitizer A 0.3 8 mass% The following photopolymerization initiator B 1 .14 mass% 0.1 9 mass% 0.0 4 mass % 6 0.1 5质量% The following alignment control agent C glutaraldehyde methyl ethyl ketone-22- 200827857

Photopolymerization initiator B

On the rubbing treatment surface of the alignment film formed as described above, the coating liquid for the optically anisotropic layer is continuously applied by a bar coater, dried and heated (alignment aging), and then irradiated with ultraviolet rays to obtain a rod-like liquid crystal property. The molecules are fixed in a horizontal alignment state to form an optically anisotropic layer 1 (thickness 1.1 μm). The formed optically anisotropic layer 1 was transferred onto a glass substrate, and the birefringence characteristics were measured, and the knot/fruit Νζ値 was 1, and Re 値 was M3 nm. The retardation axis is oriented in a direction orthogonal to the longitudinal direction (friction direction) of the film. -23 - 200827857 &lt;Formation of optically anisotropic layer 2 composed of discotic liquid crystal composition&gt; (Formation of alignment film) On the other surface of film 1, with a wire coater at 20 ml/m2 An alignment film coating liquid having the following composition was applied. The film was formed by drying at 60 ° C for 60 seconds and then drying at 100 ° C for 120 seconds. Next, the formed film is subjected to a rubbing treatment in a direction parallel to the direction of the slow axis of the film 1 to form an alignment film.

1 〇 parts by mass 3 7 1 part by mass 1 1 9 parts by mass 0.5 parts by mass 3. 3 parts by mass of the composition of the alignment film coating liquid The following modified polyvinyl alcohol water methanol glutaraldehyde fluorinated tetramethylammonium modified polyethylene alcohol

—^CH2-CH—ί-fcH2-CH-U_CH2_CH—VV 2 I /863V I /12V I IlJ . CH3 OH OCOCHs oconhch2ch2ococ=ch2 (Formation of optical anisotropic layer 2) Next, on the rubbing treatment surface of the alignment film On the top, use #4 wire rod to coat 1.8 g of the following discotic liquid crystalline compound, 0.2 g of ethylene oxide modified trimethylolpropane triacrylate (v#3 60, Osaka Organic Chemicals Co., Ltd. )), 0.06 g of photopolymerization initiator (Irgacure 907, manufactured by Ciba-Geigy Co., Ltd.), 0.02 g of sensitizer (Kayacure DETX, manufactured by Nippon Kayaku Co., Ltd.), and 0.01 g of air interface side vertical alignment agent (P- 6)-24- dissolved in 3.9 g of methyl ethyl ketone

200827857 solution. Paste it in a metal frame at a thermostat c at 12 ° C to align the discotic liquid crystal compound. Then, at a high pressure mercury lamp of 100 ° C, the UVV of 30 seconds was irradiated to cross-link the dish, and then left to cool to room temperature. Layer 2 is formed as such. Disc-like liquid crystalline compound ((H2)4-〇C〇-CH=CH2 household heated for 3 minutes, using 120 W/cm: liquid crystal compound. Optical anisotropy Air interface side vertical alignment agent P-6

f fb3 CO2CH2CH2OH C02C4Hg 0〇2Η a/blA2/b3-33/28/33/6 Mw^OOO The optically anisotropic layer 2 formed is transferred to the glass iridium refractive index, and the result is Nz値 is 0, and Re値 is 142nm. It is parallel to the rubbing direction of the alignment film. The transparent film 10 having the optically anisotropic layer 2 on the other surface is formed on the one surface of the film 1 as described above. The in-plane retardation 値Re of the transparent film 1 is measured. As a result, the transparent film 10 is in the thickness direction. Nz値 is in the 0~ learning directional layer 2 is Νζ = 0, film 1 is Nz = 0.5, layer 1 is Nz = l), and the in-plane hysteresis of wavelength 550 nm is transparent in the embodiment of the present invention. film. For the i-substrate, measure the direction of the double-latency axis. At a wavelength of 550 nm 焉 5 6 0 nm 0 , 1 monotonically increases (optical optical anisotropy Re is 5 6 Onm, -25-200827857. For the transparent film 10 produced, Axometrics AxoScan is used to measure a wavelength of 550 nm. CR1 on the front, CRl = 〇. In addition, CR2 with azimuth angle of 45°, 135 degrees, 225 degrees, and 315 degrees is measured at a polar angle of 60°, and the azimuth angle is 45 degrees and 225 degrees is CR2 = 3 2 nm. Azimuth angle 1 CR2 = -3 2nm at 35 degrees and 3 15 degrees. That is, the absolute enthalpy of CR2 with azimuth angles of 45 degrees, 135 degrees, 225 degrees, and 3 15 degrees is roughly equal to 32 nm. &lt;Production of polarizing plate 1 & A roll of polyvinyl alcohol film having a thickness of 80 μm was continuously stretched 5 times in an aqueous solution of iodine to obtain a polarizing film by drying. Polyvinyl alcohol was used as PVA-11 7Η manufactured by Kuraray. On one side of the polarizing film The transparent film 10 was superposed on the other surface, and the Tackfilm TD8 0U manufactured by Fujifilm Co., Ltd., which was used as a protective film, was laminated on the other surface to prepare a polarizing plate 10. Further, when the transparent film 10 was superposed on the polarizing film, the optical film of the transparent film 10 was made. The surface of the different directional layer 1 is in contact with the polarizing film and overlaps. With Axoscan The normalized polarizing ability vector P' of the polarizing plate 10 is measured. The polar angle is 60 degrees from the normal direction of the film surface, and the azimuth angle is the azimuth angle when the retardation axis in the film plane is used as the azimuth angle. In the direction of 45 degrees, light is incident, and the transparent film 1 〇 is measured on the exit side of the polarizing film, and the absolute value of the component P45' of the normalized polarizing ability vector P' is 0.995. [Embodiment 2] &lt;Polarizing plate 1 1 Production> When the transparent film 1 〇 is superposed on the polarizing film, the surface of the optically anisotropic layer 2 of the transparent film 10 is brought into contact with the polarizing film and bonded, and the same as in the first embodiment. Method, the polarizing plate 1 of Example 2 was produced. -26- 200827857 The normalized polarizing ability vector P' of the polarizing plate 1 1 was measured by Axo scan, and the polar angle was 60 degrees from the normal direction of the film surface, and When the azimuth angle in the film plane is 0 degree, the light is incident in the direction of the azimuth angle of 45 degrees, and the transparent film is placed on the exit side of the polarizing film, and the component P45 of the normalized polarization ability vector P' is measured. 'The absolute 値 is 0.995. [The seal of the liquid crystal display device Packing and Evaluation] Using the polarizing plates 1, 10, and 11 produced in Comparative Example 1, Example 1, and Example 2, respectively, liquid crystal display devices were produced. Specifically, each of the polarizing plates 1, 1 and 11 was used. A polarizing plate (a protective layer of a polarizing plate, Tackfilm is a Z-Tack manufactured by Fuko Film Co., Ltd.) is used, and an IP S-type liquid crystal cell is sandwiched to produce a liquid crystal display device. Note that the thin film 1 of the polarizing plates 1, 10 and 1 1 and the transparent films 1 and 1 are respectively sandwiched by the liquid crystal cell side. Further, the in-plane absorption axes of the two polarizing plates sandwiching the liquid crystal cell are orthogonal, and the in-plane absorption axes of the respective polarizing plates 1, 1 and 11 are in-plane with the in-plane phase of the IP s type liquid crystal cell. Parallel way to clamp. The IP S type liquid crystal cell has a birefringence of 30 Onm and is formed in a horizontal alignment manner in a voltage application state. The liquid crystal system uses the ZLI-4792 from Merck. The transmittance of the liquid state of the liquid crystal display device thus produced, that is, the black state, was measured at a polar angle of 60 degrees and an azimuth angle of 45 degrees, with respect to the liquid crystal display device of the polarizing plate 1 of Comparative Example 1. 35% is 0.02% when the liquid crystal display device of the polarizing plate of Example 1 is used, and 液晶2% when the liquid crystal display device of the polarizing plate 1 of Example 2 is used. From this, it can be understood that the transmittance of the polarizing plates 1 and 11 in the black state of the embodiment of the present invention is small as compared with the polarizing plate 1 of Comparative Example 1, and the contrast is further improved. -27 - 200827857 BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a cross-sectional model view showing an example of a polarizing plate of the present invention. Fig. 2 is a model diagram showing an arbitrary linearly polarized state point p and a _ extinction point Q of a Poincare sphere. Fig. 3 is a model diagram showing a trajectory of a conventional conversion example of the extinction point Q of the stomach from the arbitrary linearly polarized state point p of the Poincare. Fig. 4 is a model diagram showing a track of a conventional conversion example from the arbitrary linearly polarized state point P of the Poincare sphere to the extinction point Q for each of the R light, the G light, and the B light. Fig. 5 is a model diagram showing a trajectory of a conversion example from the arbitrary linearly polarized state point P of the Poincare sphere to the extinction point Q thereof, using the transparent film of the present invention for each of the R light, the G light, and the B light. [Main component symbol description] 10 Polarizing plate 12 Polarizing mirror 14 Protective film 16 Transparent film of the invention -28-

Claims (1)

200827857 X. Patent application scope: 1. A transparent film comprising a region in which the Nz 法 in the normal direction of the film surface increases monotonously or monotonically decreases from 0 to 1, and the in-plane retardation 値Re of wavelength 5 5 Onm is 510 〜 610 nm; but Nz = 0.5 + Rth(5 5 0)/Re(5 5 0), wherein Rth(5 5 0) and Re(5 5 0) are each a hysteresis in the thickness direction of a wavelength of 550 nm. In-plane delay. 2. A transparent film as claimed in claim 1 which contains deuterated cellulose as a main component. ^ 3. The transparent film of claim 1, which contains a polymer resin having an alicyclic structure as a main component. 4. A transparent film characterized by having an optical anisotropy in a plane, a circular hysteresis (CRE1) in a normal direction of the film surface of about 0, and a polar angle of 60 degrees from a normal direction of the film surface, and The absolute enthalpy of the circular hysteresis (CRE2) of the light incident in four directions of azimuth angles of 45 degrees, 135 degrees, 225 degrees, and 315 degrees when the slow phase axis in the film plane is used as the azimuth angle Each is roughly equal and not awkward. ® 5. The transparent film of claim 4, wherein the absolute enthalpy of CRE2 is 32 to 38 nm. 6. The transparent film of claim 1 of the patent application, wherein there are two or more layers different from each other by Nz値. The multilayer structure is constructed. 7. The transparent film of claim 6, wherein the polymer film has at least one layer of a polymer film and an optically anisotropic layer each composed of the same or different liquid crystal compositions on both sides. A polarizing plate having a polarizing film and a transparent film according to any one of claims 1 to 7-29-200827857. A liquid crystal display device comprising a liquid crystal cell and a polarizing plate according to item 8 of the patent application. A liquid crystal display device having a liquid crystal cell and at least one polarizing film, wherein the polarizing film and the liquid crystal cell have any one of the first to seventh aspects of the patent application. Transparent film. -30-