JP2005321527A - Liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an IPS liquid crystal display remarkably improved not only in display quality but also in a visibility angle in a simple configuration. <P>SOLUTION: The liquid crystal display has: a laminating polarizing plate formed by cutting a long laminate made by continuously bonding a first polarizing film 8 and a first optical anisotropic layer 10 in a long state respectively, into prescribed size; a first substrate 13; a liquid crystal layer 15; and a second substrate 17, arranged in the order. The absorption axis of the first polarizing film 8 and the retardation axis 11 of the first optical anisotropic layer 10 are substantially orthogonal, liquid crystal molecules of the liquid crystal layer are orientated in substantially parallel to the surface of the pair of the substrates during black display, and the retardation axis 11 of the first optical anisotropic layer 10 is substantially parallel in a direction of a retardation axis 16 of the liquid crystal molecules during black display. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a liquid crystal display device, and more particularly to an in-plane switching mode liquid crystal display device that performs display by applying a horizontal electric field to liquid crystal molecules aligned in a horizontal direction.

  As a liquid crystal display device, a so-called TN mode, in which a liquid crystal layer in which nematic liquid crystal is twisted and arranged between two orthogonal polarizing plates, and an electric field is applied in a direction perpendicular to the substrate is widely used. In this system, since the liquid crystal rises with respect to the substrate during black display, birefringence occurs due to liquid crystal molecules when viewed from an oblique direction, and light leakage occurs. To solve this problem, a system for optically compensating the liquid crystal cell and preventing this light leakage by using a film in which liquid crystal molecules are hybrid-aligned has been put into practical use. However, even if liquid crystal molecules are used, it is very difficult to completely optically compensate the liquid crystal cell without any problem, resulting in a problem that gradation reversal in the lower direction of the screen cannot be suppressed.

  In order to solve such a problem, a liquid crystal display device using a so-called in-plane switching (IPS) mode in which a lateral electric field is applied to the liquid crystal, or a liquid crystal having a negative dielectric anisotropy is vertically aligned in the panel. A vertical alignment (VA) mode in which alignment is divided by protrusions and slit electrodes has been proposed and put into practical use. In recent years, these panels have been developed not only for monitor applications but also for TV applications, and screen brightness has been greatly improved accordingly. For this reason, slight light leakage in the diagonally oblique incidence direction during black display, which has not been considered as a problem in these operation modes, has become apparent as a cause of deterioration in display quality.

  As one means for improving the color tone and the viewing angle of black display, the arrangement of an optical compensation material having birefringence characteristics between the liquid crystal layer and the polarizing plate is also studied in the IPS mode. For example, by arranging a birefringent medium having an optical axis orthogonal to each other to compensate for the increase / decrease in retardation of the liquid crystal layer during tilting, a white display or a halftone display is diagonally arranged between the substrate and the polarizing plate. It is disclosed that coloring can be improved when viewing directly from (see Patent Document 1). Further, a method using an optical compensation film made of a styrene polymer having a negative intrinsic birefringence or a discotic liquid crystalline compound (see Patent Documents 2, 3, and 4) or an optical compensation film having a positive birefringence and an optical axis. A method of combining a film in the plane of a film with a film having a positive birefringence and an optical axis in the normal direction of the film (see Patent Document 5), a biaxial optical compensation sheet having a retardation of half wavelength Using a film having a negative retardation as a protective film of a polarizing plate and providing an optical compensation layer having a positive retardation on this surface (see Patent Document 7) Has been.

Japanese Patent Laid-Open No. 9-80424 Japanese Patent Laid-Open No. 10-54982 JP-A-11-202323 Japanese Patent Laid-Open No. 9-292522 JP 11-133408 A JP-A-11-305217 JP-A-10-307291

  However, many of the proposed methods are methods that improve the viewing angle by canceling the birefringence anisotropy of the liquid crystal in the liquid crystal cell, so the polarization axis crossing angle when the orthogonal polarizing plate is viewed from an oblique direction. There is a problem that the light leakage based on the deviation from orthogonality cannot be solved sufficiently. Even in a system that can compensate for this light leakage, it is very difficult to completely optically compensate the liquid crystal cell without any problem. Furthermore, in the optical compensation sheet for an IPS mode liquid crystal cell that performs optical compensation with a stretched birefringent polymer film, it is necessary to use a plurality of films. As a result, the thickness of the optical compensation sheet is increased, and the display device is made thinner. It is disadvantageous. In addition, since an adhesive layer is used for laminating a polarizing plate and a plurality of stretched films, the adhesive layer contracts due to changes in temperature and humidity, and defects such as peeling and warping between films may occur. In addition, since a plurality of films are bonded to each other after being cut to a predetermined size, the number of processes is large, and the ratio of occurrence of defective products in which the shaft angles of the respective films are shifted at the time of bonding is high. there were.

  The present invention has been made in view of the above-mentioned problems, and has an object to provide a liquid crystal display device, particularly an IPS mode liquid crystal display device, which has a simple structure and not only display quality but also a significantly improved viewing angle. To do.

Means for solving the above-mentioned problems are as follows.
(1) a laminated polarizing plate obtained by cutting a long laminate in which the first polarizing film and the first optically anisotropic layer are continuously bonded in a long state into a predetermined size; A liquid crystal display device in which a first substrate, a liquid crystal layer, and a second substrate are arranged in this order, wherein an absorption axis of the first polarizing film and a slow axis of the first optical anisotropic layer Are substantially orthogonal, the liquid crystal molecules of the liquid crystal layer are aligned substantially parallel to the surfaces of the pair of substrates during black display, and the slow phase of the first optically anisotropic layer A liquid crystal display device whose axis is substantially parallel to the slow axis direction of liquid crystal molecules during black display.
(2) The absorption axis of the first polarizing film is substantially parallel to the long longitudinal direction, and the slow axis of the first optical anisotropic layer is relative to the long longitudinal direction. (1) The liquid crystal display device according to (1), comprising a laminated polarizing plate obtained by cutting a long laminate substantially orthogonal to a predetermined size.
(3) The absorption axis of the first polarizing film is substantially orthogonal to the long longitudinal direction, and the slow axis of the first optical anisotropic layer is relative to the long longitudinal direction. The liquid crystal display device according to (1), further comprising a laminated polarizing plate obtained by cutting a substantially parallel long laminate into a predetermined size.
(4) When the in-plane retardation (Re) and the thickness direction retardation (Rth) of the optically anisotropic layer are defined by the following formulas (1) and (2), respectively, The liquid crystal display device according to any one of (1) to (3), wherein Re of the isotropic layer is 60 to 200 nm and Rth is 30 to 100 nm.
Re = (nx−ny) × d (1)
Rth = {(nx + ny) / 2−nz} × d (2)
(In the formula, nx and ny are the refractive indexes in two directions orthogonal to each other in the plane of the optically anisotropic layer (nx ≧ ny), nz is the refractive index in the thickness direction, and d is the thickness of the optically anisotropic layer ( nm).)
(5) The liquid crystal display device according to any one of (1) to (4), wherein the first optically anisotropic layer includes a layer that exhibits optical anisotropy by aligning a liquid crystalline compound.
(6) The liquid crystal display device according to any one of (1) to (4), wherein the first optically anisotropic layer includes a layer that exhibits optical anisotropy by stretching a polymer film.

(7) A second optical anisotropic layer is included between the first polarizing film and the first substrate, the Re of the second optical anisotropic layer is 0 to 50 nm, and Rth is − The liquid crystal display device according to any one of (1) to (6), which is 200 to -50 nm.
(8) The liquid crystal display device according to (7), wherein the first polarizing film, the first optical anisotropic layer, the second optical anisotropic layer, and the first substrate are laminated in this order.
(9) After laminating a laminate of the first polarizing film, the first optical anisotropic layer, and the second optical anisotropic layer in a long state to form a laminate, the laminate The liquid crystal display device according to (7) or (8), comprising a laminated polarizing plate obtained by cutting a sheet into a predetermined size.
(10) The liquid crystal display device according to any one of (7) to (9), wherein the second optically anisotropic layer includes a layer that exhibits optical anisotropy by aligning a liquid crystalline compound.
(11) The liquid crystal display device according to any one of (7) to (9), wherein the second optically anisotropic layer includes a layer that exhibits optical anisotropy by stretching a polymer film.
(12) One or more optical anisotropic layers are further included between the first polarizing film and the first optical anisotropic layer, and the total Re of the one or more optical anisotropic layers is 0. The liquid crystal display device according to any one of (1) to (11), having a thickness of ˜20 nm and an Rth of −60 to 60 nm.
(13) Only a substantially optically isotropic adhesive layer or pressure-sensitive adhesive layer is included between the first polarizing film and the first optically anisotropic layer. The liquid crystal display device according to any one of 11).
(14) The liquid crystal display device according to any one of (1) to (13), further including a second polarizing film on an outer side of the second substrate.
“Outside” means the side opposite to the side where the liquid crystal cell is disposed.
(15) having a pair of protective films arranged with the second polarizing film sandwiched therebetween, wherein Rth of the protective film on the side close to the liquid crystal layer of the pair of protective films is −60 to 60 nm Liquid crystal display device.
(16) The liquid crystal display device according to (14), wherein only a substantially optically isotropic adhesive layer or pressure-sensitive adhesive layer is included between the second substrate and the second polarizing film.

(17) At least the long first polarizing film and the long first optical anisotropic layer are continuously bonded in a long state, and the absorption axis of the first polarizing film and the A first step of producing a long laminate in which the slow axis of the first optically anisotropic layer is substantially perpendicular, and a laminate polarizing plate is produced by cutting the laminate into a predetermined size; A second step, a liquid crystal cell in which liquid crystal molecules are aligned substantially parallel to the surfaces of a pair of substrates during black display, and the laminated polarizing plate, a slow phase of the first optically anisotropic layer And a third step of arranging the axis so as to be substantially parallel to the slow axis direction of the liquid crystal molecules during black display.
(18) The long first polarizing film has an absorption axis substantially parallel to the longitudinal direction, and the long first optically anisotropic layer is substantially parallel to the longitudinal direction. In the first step, the long first polarizing film and the long first optically anisotropic layer are laminated with a roll-to-roll. (17) A method for producing a long laminate.
(19) The long first polarizing film has an absorption axis substantially perpendicular to the longitudinal direction, and the long first optically anisotropic layer is substantially parallel to the longitudinal direction. In the first step, the long first polarizing film and the long first optically anisotropic layer are laminated with a roll-to-roll. (17) A method for producing a long laminate.

  According to the present invention, it is possible to provide a liquid crystal display device, particularly an IPS mode liquid crystal display device, which has a simple structure and has not only improved display quality but also significantly improved viewing angle.

BEST MODE FOR CARRYING OUT THE INVENTION

  Hereinafter, embodiments of the optical compensation film and the liquid crystal display device of the present invention will be described in order. In the present specification, a numerical range represented by using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value. FIG. 1 is a schematic diagram showing an example of a pixel region of the liquid crystal display device of the present invention. FIG. 2 is a schematic view of an embodiment of the liquid crystal display device of the present invention.

  In the present specification, “parallel” and “orthogonal” mean that the angle is within a range of strictly less than ± 10 °. In this range, an error from a strict angle is preferably less than ± 5 °, and more preferably less than ± 2 °. Further, “substantially vertical” means within a range of less than ± 20 ° from a strict vertical angle. In this range, an error from a strict angle is preferably less than ± 15 °, and more preferably less than ± 10 °. Further, the “slow axis” means a direction in which the refractive index is maximized. Further, the measurement wavelength of the refractive index is a value at λ = 550 nm in the visible light region unless otherwise specified.

  In this specification, “polarizing plate” is cut into a size to be incorporated into a long polarizing plate and a liquid crystal device unless otherwise specified (in this specification, “cutting” includes “punching” and “cutting out”. It is used in the meaning including both of the polarizing plates. In this specification, “polarizing film” and “polarizing plate” are distinguished from each other. “Polarizing plate” means a laminate having a transparent protective film for protecting the polarizing film on at least one side of the “polarizing film”. It shall be.

Hereinafter, embodiments of the liquid crystal display device of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram showing an example of a pixel region of the liquid crystal display device of the present invention. FIG. 2 is a schematic view of an embodiment of the liquid crystal display device of the present invention.
[Liquid Crystal Display]
The liquid crystal display device shown in FIG. 2 includes polarizing films 8 and 20, a first optical anisotropic layer 10, a second optical anisotropic layer 12, substrates 13 and 17, and a liquid crystal layer 15. . The polarizing films 8 and 20 are sandwiched between protective films 7a and 7b and 19a and 19b, respectively.

  In the liquid crystal display device of FIG. 2, the liquid crystal cell includes substrates 13 and 17 and a liquid crystal layer 15 sandwiched between them. The product Δn · d of the thickness d (μm) of the liquid crystal layer and the refractive index anisotropy Δn is optimal in the range of 0.2 to 0.4 μm for the IPS type having no twisted structure in the transmission mode. In this range, the white display luminance is high and the black display luminance is small, so that a bright and high-contrast display device can be obtained. An alignment film (not shown in FIG. 2) is formed on the surfaces of the substrates 13 and 17 that are in contact with the liquid crystal layer 15, and the liquid crystal molecules are aligned substantially parallel to the surface of the substrate and applied on the alignment film. By the rubbing treatment directions 14 and 18 and the like, the liquid crystal molecule alignment direction in the no-voltage application state or the low application state is controlled, and the direction of the slow axis 16 is determined. Further, an electrode (not shown in FIG. 2) capable of applying a voltage to the liquid crystal molecules is formed on the inner surface of the substrate 13 or 17.

FIG. 1 schematically shows the alignment of liquid crystal molecules in one pixel region of the liquid crystal layer 15. FIG. 1 shows the alignment of liquid crystal molecules in a very small area corresponding to one pixel of the liquid crystal layer 15 in the rubbing direction 4 of the alignment film formed on the inner surfaces of the substrates 13 and 17 and the substrates 13 and 17. It is the schematic diagram shown with the electrodes 2 and 3 which can apply a voltage to the liquid crystal molecule formed in the inner surface. When active driving is performed using a nematic liquid crystal having positive dielectric anisotropy as a field effect liquid crystal, the liquid crystal molecule alignment directions in a no voltage application state or a low application state are 5a and 5b. An indication is obtained. When applied between the electrodes 2 and 3, the liquid crystal molecules change their alignment direction in the directions of 6 a and 6 b in accordance with the voltage. Usually, bright display is performed in this state.
The liquid crystal cell used in the present invention is not limited to the IPS mode, and any liquid crystal display device in which liquid crystal molecules are aligned substantially parallel to the surfaces of the pair of substrates during black display can be used. It can be used suitably. Examples thereof include a ferroelectric liquid crystal display device, an antiferroelectric liquid crystal display device, and an ECB type liquid crystal display device.

  In FIG. 2 again, the polarizing film 8, the pair of protective films 7a and 7b of the polarizing film 8, and the first optical anisotropic layer 10 are incorporated in the liquid crystal display device as an integrated laminated polarizing plate. . The laminated polarizing plate used in the liquid crystal display device of the present invention has a long form in which a long polarizing film and a long first optical anisotropic layer are laminated, and before being incorporated into the liquid crystal display device. , Cut to the appropriate size. Details of the laminated polarizing plate will be described later. The second optically anisotropic layer 12 may be incorporated in the liquid crystal display device as a part of the laminated polarizing plate, or may be incorporated in the liquid crystal display device as an independent member. The second optically anisotropic layer 12 is preferably a layer in which nx and ny are substantially equal, that is, the in-plane anisotropy is small. Specifically, the in-plane retardation Re of the second optically anisotropic layer is preferably 0 to 50 nm. On the other hand, the retardation Rth in the thickness direction is preferably −200 to −50 nm. Details of the second optically anisotropic layer will also be described later.

  In the liquid crystal display device of FIG. 2, the transmission axis 9 of the polarizing film 8 of the laminated polarizing plate and the transmission axis 21 of the polarizing film 20 are arranged orthogonally. The slow axis 11 of the first optically anisotropic layer 10 is parallel to the transmission axis 9 of the polarizing film 8 and the slow axis direction 16 of the liquid crystal molecules in the liquid crystal layer 15 during black display. Furthermore, the slow axis 11 of the first optical anisotropic layer 10 is orthogonal to the absorption axis (not shown in FIG. 2) of the polarizing film 8, that is, parallel to the transmission axis 9 of the polarizing film 8.

  In the liquid crystal display device of FIG. 2, the configuration in which the polarizing film 8 is sandwiched between the two protective films 7a and 7b is shown, but the protective film 7b may be omitted. That is, the polarizing film 8 and the first optically anisotropic layer 10 are laminated in contact with each other, and a layer made of an optically isotropic adhesive or pressure-sensitive adhesive (for example, polyvinyl alcohol type, acrylic type) is interposed between them. , An epoxy-based, ethylene-vinyl acetate-based, rubber-based adhesive layer) may be included. The optically isotropic adhesive layer is described in JP-A-6-242434. However, when the protective film 7 b is not disposed, the first optical anisotropic layer 10 or the optically isotropic adhesive layer needs to have a function of protecting the polarizing film 8. When the protective film 7b is disposed, Re of the protective film is preferably 0 to 20 nm, more preferably 0 to 10 nm, and most preferably 0 to 5 nm. Furthermore, Rth is preferably −60 nm to 60 nm, more preferably −40 nm to 40 nm, and most preferably −20 nm to 20 nm. In addition to the protective film 7b, when an optically anisotropic layer is included between the polarizing film 8 and the first optically anisotropic layer 10, the polarizing film 8 and the first film including the protective film 7b are also included. The total Re of all layers contained between the optically anisotropic layer 10 is preferably 0 to 20 nm, and Rth is preferably −60 to 60 nm. On the other hand, the polarizing film 20 is also sandwiched between the two protective films 19a and 19b, but the protective film 19a on the side close to the liquid crystal layer 15 may not be provided. When the protective film 19a is disposed, Re of the protective film is preferably 0 to 20 nm, more preferably 0 to 10 nm, and most preferably 0 to 5 nm. Furthermore, Rth is preferably −60 nm to 60 nm, more preferably −40 nm to 40 nm, and most preferably −20 nm to 20 nm.

  The first optical anisotropic layer and the second optical anisotropic layer may be disposed between the liquid crystal cell and the viewing side polarizing film with reference to the position of the liquid crystal cell. May be disposed between the liquid crystal cell and the polarizing film on the back side, but it is preferable in terms of yield to be disposed between the liquid crystal cell and the polarizing film on the back side. In any embodiment, in the configuration of FIG. 2, it is preferable to arrange the second optically anisotropic layer so as to be closer to the liquid crystal cell.

  The liquid crystal display device of the present invention is not limited to the configuration shown in FIGS. 1 and 2, and may include other members. For example, a color filter may be disposed between the liquid crystal layer and the polarizing film. Further, an antireflection treatment or a hard coat may be applied to the surface of the protective film of the polarizing film. Moreover, you may use what gave electroconductivity to the structural member. In the case of use as a transmission type, a cold cathode or a hot cathode fluorescent tube, or a backlight having a light emitting diode, a field emission element, or an electroluminescent element as a light source can be disposed on the back surface. In this case, the arrangement of the backlight may be on the upper side or the lower side in FIG. 2, but it is less necessary to combine with a polarizing plate that has been subjected to antireflection or antistatic treatment, which has a slightly higher defect rate. It is more preferable to lower the backlight. In addition, a reflective polarizing plate, a diffusion plate, a prism sheet, or a light guide plate can be disposed between the liquid crystal layer and the backlight. Further, as described above, the liquid crystal display device of the present invention may be of a reflective type. In such a case, only one polarizing plate may be disposed on the observation side, and the back side of the liquid crystal cell or the lower side of the liquid crystal cell A reflective film is disposed on the inner surface of the substrate. Of course, it is also possible to provide a front light using the light source on the liquid crystal cell observation side.

  The liquid crystal display device of the present invention includes an image direct view type, an image projection type, and a light modulation type. The present invention is particularly effective when applied to an active matrix liquid crystal display device using a three-terminal or two-terminal semiconductor element such as TFT or MIM. Of course, a mode applied to a passive matrix liquid crystal display device called time-division driving is also effective.

  Hereinafter, preferred optical characteristics of various members usable in the liquid crystal display device of the present invention, materials used for the members, manufacturing methods thereof, and the like will be described in detail.

[Laminated polarizing plate]
The laminated polarizing plate used in the liquid crystal display device of the present invention has at least a polarizing film and a first optical anisotropic layer. Originally, a laminate produced by laminating a long polarizing film and a long first optically anisotropic layer is cut into a predetermined size. The laminated polarizing plate may have one or more layers such as a protective film for protecting the polarizing film between the polarizing film and the first optically anisotropic layer, or the first optically anisotropic layer. The protective layer may also serve as a protective film. Furthermore, it is preferable to have a protective film on the surface opposite to the surface having the first optically anisotropic layer of the polarizing film. The polarizing film and the first optical anisotropic layer are laminated with the absorption axis of the polarizing film and the slow axis of the first optical anisotropic layer orthogonal to each other. For example, by using a long polarizing film whose absorption axis is parallel to the longitudinal direction and a long optical film (first optical anisotropic layer) having a slow axis in a direction perpendicular to the longitudinal direction, or By using a long polarizing film whose absorption axis is perpendicular to the longitudinal direction and a long optical film (first optical anisotropic layer) having a slow axis in a direction parallel to the longitudinal direction, these The film is bonded roll-to-roll with an adhesive or a pressure-sensitive adhesive to obtain a long laminated body, and then the laminated body is cut into a predetermined size to form a laminated polarizing plate on a liquid crystal display device. Can be incorporated. By performing the bonding process in a long state, it becomes easy to laminate the angle between the absorption axis of the polarizing film and the slow axis of the first optically anisotropic layer orthogonally. As a result, extremely accurate bonding is possible, and productivity is improved.

[First optically anisotropic layer]
The first optical anisotropic layer included in the liquid crystal display device of the present invention uses the in-plane refractive indexes nx and ny (nx ≧ ny), the refractive index nz in the thickness direction, and the thickness d of the film. In-plane retardation (Re) defined by Re = (nx−ny) × d is 60 to 200 nm, more preferably 70 to 180 nm, and still more preferably 90 to 160 nm. Moreover, the retardation (Rth) in the thickness direction defined by Rth = ((nx + ny) / 2−nz) × d is 30 to 100 nm, more preferably 35 to 90 nm, and more preferably 45 to 80 nm. Is more preferable. Moreover, it is preferable that Nz defined by Nz = (nx−nz) / (nx−ny) is 0.8 to 1.5. If it is 0.8 or less, Re required for improving the contrast becomes too large, the allowable range of the bonding angle with the polarizing plate becomes narrow, and the yield decreases, which is not preferable. On the other hand, if it exceeds 1.5, another optically anisotropic layer is indispensable for improving the contrast, and its Rth is undesirably increased.

  The material and form of the first optically anisotropic layer are not particularly limited as long as they have the optical characteristics and are long. For example, it is formed by coating or transferring a low-molecular or high-molecular liquid crystalline compound on a transparent support, a retardation film made of a birefringent polymer film, a heated film after coating a high-molecular compound on a transparent support, and a transparent support. Any retardation film having a retardation layer can be used. Moreover, each can also be laminated | stacked and used.

  The first optically anisotropic layer preferably has an optical axis substantially parallel to the layer plane. Such an optically anisotropic layer may be a stretched polymer film, or may be a layer formed by fixing a substantially horizontal (homogeneous) aligned liquid crystal compound.

[Formation of first optically anisotropic layer by liquid crystal compound]
The substantially horizontal (homogeneous) orientation of the liquid crystal molecules means that the average angle between the director direction of the liquid crystal molecules and the layer plane is in the range of 0 to 20 °. The liquid crystalline molecules are preferably fixed in an aligned state, and more preferably fixed by polymerization. As long as the optical characteristics are satisfied, the type of the liquid crystalline compound is not particularly limited. For example, after forming a low-molecular liquid crystalline compound in a nematic alignment in a liquid crystal state, an optically anisotropic layer obtained by fixing by photocrosslinking or thermal crosslinking, or after forming a polymer liquid crystalline compound in a nematic alignment in a liquid crystal state, An optically anisotropic layer obtained by fixing the orientation by cooling can be used. In the present invention, even when a liquid crystalline compound is used for the optically anisotropic layer, the optically anisotropic layer is a layer formed by fixing the compound by polymerization or the like, and thus becomes a layer. After that, it is no longer necessary to show liquid crystallinity.

  In the embodiment in which the first optically anisotropic layer is formed by fixing the orientation of liquid crystalline molecules, the first optically anisotropic layer can be formed from a composition containing a liquid crystalline compound. As the liquid crystal compound, a rod-like liquid crystal compound is preferably used. The liquid crystalline compound is preferably fixed in a nematic alignment state, and more preferably fixed by a polymerization reaction. Examples of rod-like liquid crystalline compounds include azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, alkoxy-substituted phenylpyrimidines. , Phenyldioxanes, tolanes and alkenylcyclohexylbenzonitriles are preferably used. Not only the above low-molecular liquid crystalline compounds but also high-molecular liquid crystalline compounds can be used. It is more preferable to fix the alignment of the rod-like liquid crystal compound by polymerization. As the liquid crystal molecules, those having a partial structure capable of causing polymerization or crosslinking reaction by actinic rays, electron beams, heat, or the like are preferably used. The number of the partial structures is 1 to 6, preferably 1 to 3. As the polymerizable rod-like liquid crystalline compound, Makromol. Chem. 190, 2255 (1989), Advanced Materials 5, 107 (1993), US Pat. No. 4,683,327, US Pat. No. 5,622,648, US Pat. No. 5,770,107, WO 95/22586 No. 95/24455, No. 97/00600, No. 98/23580, No. 98/52905, JP-A-1-272551, No. 6-16616, No. 7-110469, The compounds described in JP-A-11-80081 and JP-A-2001-328773 can be used.

  The optically anisotropic layer can be formed by applying a liquid crystal compound and, if necessary, a coating liquid containing a polymerizable initiator and optional components on the alignment film. As a solvent used for preparing the coating solution, an organic solvent is preferably used. Examples of organic solvents include amides (eg, N, N-dimethylformamide), sulfoxides (eg, dimethyl sulfoxide), heterocyclic compounds (eg, pyridine), hydrocarbons (eg, benzene, hexane), alkyl halides (eg, , Chloroform, dichloromethane), esters (eg, methyl acetate, butyl acetate), ketones (eg, acetone, methyl ethyl ketone), ethers (eg, tetrahydrofuran, 1,2-dimethoxyethane). Alkyl halides and ketones are preferred. Two or more organic solvents may be used in combination. The coating liquid can be applied by a known method (eg, extrusion coating method, direct gravure coating method, reverse gravure coating method, die coating method). The thickness of the optically anisotropic layer is preferably 0.5 to 100 μm, and more preferably 0.5 to 30 μm.

The alignment state of the aligned liquid crystal molecules is preferably fixed by a polymerization reaction. The polymerization reaction includes a thermal polymerization reaction using a thermal polymerization initiator and a photopolymerization reaction using a photopolymerization initiator, and a photopolymerization reaction is preferred. Examples of the photopolymerization initiator include α-carbonyl compounds (described in US Pat. Nos. 2,367,661 and 2,367,670), acyloin ether (described in US Pat. No. 2,448,828), α-hydrocarbon substituted aromatic acyloin. Compound (described in US Pat. No. 2,722,512), polynuclear quinone compound (described in US Pat. Nos. 3,046,127 and 2,951,758), a combination of triarylimidazole dimer and p-aminophenyl ketone (US Pat. No. 3,549,367) Acridine and phenazine compounds (JP-A-60-105667, U.S. Pat. No. 4,239,850) and oxadiazole compounds (U.S. Pat. No. 4,212,970). The amount of the photopolymerization initiator used is preferably 0.01 to 20% by mass, more preferably 0.5 to 5% by mass, based on the solid content of the coating solution. It is preferable to use ultraviolet rays for light irradiation for polymerization of liquid crystalline molecules. Irradiation energy is preferably 20~5000mJ / cm ^2, further preferably 100 to 800 mJ / cm ^2. In order to accelerate the photopolymerization reaction, light irradiation may be performed under heating conditions. A protective layer may be provided on the optically anisotropic layer.

[Alignment film]
In order to define the alignment direction of the liquid crystalline molecules forming the optically anisotropic layer, it is preferable to use an alignment film. The alignment film is an organic compound (eg, ω-tricosanoic acid) formed by rubbing treatment of an organic compound (preferably polymer), oblique deposition of an inorganic compound, formation of a layer having a microgroove, or Langmuir-Blodgett method (LB film). , Dioctadecylmethylammonium chloride, methyl stearylate). Furthermore, an alignment film in which an alignment function is generated by application of an electric field, application of a magnetic field, or light irradiation is also known. The alignment film is preferably formed by polymer rubbing treatment. The rubbing process is performed by rubbing the surface of the alignment film several times in a certain direction with paper or cloth. It is preferable to use a cloth in which fibers having uniform length and thickness are uniformly planted. In addition, after the liquid crystalline molecules of the optically anisotropic layer are aligned and fixed on the alignment film, the alignment state of the liquid crystalline molecules can be maintained even if the alignment film is removed. That is, the alignment film is indispensable in the production of the retardation plate in order to align the liquid crystalline molecules, but is not essential in the produced retardation plate. When the alignment film is provided between the transparent support and the optically anisotropic layer, an undercoat layer (adhesive layer) may be further provided between the transparent support and the alignment film.

  The first optically anisotropic layer is laminated with the polarizing film in a long form. An alignment film is formed by continuously applying a solution of the alignment film composition while being conveyed on a long film, the surface is continuously rubbed, and a solution containing a liquid crystal compound is continuously formed thereon. The long optically anisotropic layer can be obtained by applying the coating optically.

  The slow axis direction of the long first optically anisotropic layer is substantially parallel to or perpendicular to the film longitudinal direction. As described above, when orienting a liquid crystal compound by continuously rubbing while conveying an alignment film formed on a long film, liquid crystal molecules are aligned in a direction parallel or perpendicular to the longitudinal direction. The alignment film material can be selected as appropriate depending on the orientation. In order to develop the slow axis of the first optically anisotropic layer in parallel with the rubbing direction (that is, in parallel with the longitudinal direction), a polyvinyl alcohol-based alignment film or the like can be used. In addition, when it is desired to develop the slow axis of the first optically anisotropic layer perpendicular to the rubbing direction (that is, perpendicular to the longitudinal direction), paragraphs [0024] to [0024] of [JP-A-2002-98836]. [0210] can be used. A polarizing film using iodine, which is widely used, is manufactured by a continuous longitudinal uniaxial stretching process, and therefore has an absorption axis parallel to the longitudinal direction of the roll. Therefore, the long polarizing film stretched in a general longitudinal uniaxial direction and the long first optically anisotropic layer have the absorption axis of the polarizing film orthogonal to the slow axis of the first optically anisotropic layer. Thus, when bonding by roll-to-roll, it is preferable to use the said orthogonal orientation film.

[Other materials in optically anisotropic layer]
Along with the liquid crystal compound, a plasticizer, a surfactant, a polymerizable monomer, and the like can be used in combination to improve the uniformity of the coating film, the strength of the film, the orientation of the liquid crystal compound, and the like. These materials are preferably compatible with the liquid crystal compound and do not inhibit the alignment.

  Examples of the polymerizable monomer include radically polymerizable or cationically polymerizable compounds. Preferably, it is a polyfunctional radically polymerizable monomer and is preferably copolymerizable with the above-described polymerizable group-containing liquid crystal compound. Examples thereof include those described in paragraph numbers [0018] to [0020] in JP-A No. 2002-296423. The amount of the compound added is generally in the range of 1 to 50% by mass and preferably in the range of 5 to 30% by mass with respect to the liquid crystal molecules.

  Examples of the surfactant include conventionally known compounds, and fluorine compounds are particularly preferable. Specifically, for example, compounds described in paragraphs [0028] to [0056] in JP-A No. 2001-330725, and paragraphs [0069] to [0126] in Japanese Patent Application No. 2003-295212 are described. The compound of this is mentioned.

  The polymer used together with the liquid crystal compound is preferably capable of thickening the coating solution. A cellulose ester can be mentioned as an example of a polymer. Preferable examples of the cellulose ester include those described in paragraph [0178] of JP-A No. 2000-155216. The addition amount of the polymer is preferably in the range of 0.1 to 10% by mass, and in the range of 0.1 to 8% by mass with respect to the liquid crystal molecules so as not to inhibit the alignment of the liquid crystal compound. It is more preferable.

[Support]
In the present invention, an optically anisotropic layer formed from a liquid crystalline compound may be formed on a support. The support is preferably transparent, and specifically, the light transmittance is preferably 80% or more. The support preferably has a small wavelength dispersion. Specifically, the Re400 / Re700 ratio is preferably less than 1.2. Among these, a polymer film is preferable. The transparent support can also serve as the first optical anisotropic layer, the second optical anisotropic layer, or the polarizing plate protective film. The transparent support and the entire retardation layer may constitute the first optical anisotropic layer or the second optical anisotropic layer. The optical anisotropy of the support is preferably small, and the in-plane retardation (Re) is preferably 20 nm or less, more preferably 10 nm or less, and most preferably 5 nm or less.

  Examples of the polymer film as the support include cellulose ester, polycarbonate, polysulfone, polyethersulfone, polyacrylate and polymethacrylate films. A cellulose ester film is preferred, an acetylcellulose film is more preferred, and a triacetylcellulose film is most preferred. The polymer film is preferably formed by a solvent cast method. The thickness of the transparent support is preferably 20 to 500 μm, and more preferably 40 to 200 μm. In order to improve the adhesion between the transparent support and the layer (adhesive layer, alignment film or retardation layer) provided thereon, surface treatment (eg, glow discharge treatment, corona discharge treatment, ultraviolet (UV) treatment is applied to the transparent support. Treatment, flame treatment). An adhesive layer (undercoat layer) may be provided on the transparent support. Moreover, the average particle diameter is 10 to 100 nm in order to provide the transparent support or the long transparent support with slipperiness in the conveying process or to prevent the back surface and the surface from sticking after winding. It is preferable to use what formed the polymer layer which mixed the inorganic particle of about 5%-40% by solid content weight ratio by the application | coating or co-casting with the support body on the one side of the support body.

  The retardation layer formed from the liquid crystalline compound can also be produced by forming on a temporary support and transferring the retardation layer onto the support. Furthermore, not only one retardation layer but also a plurality of retardation layers can be laminated to constitute the first optical anisotropic layer exhibiting the above optical characteristics. In addition, the first optical anisotropic layer may be configured so that the entire laminated body of the support and the retardation layer satisfies the optical characteristics.

[Formation of first optical anisotropic layer by polymer film]
The first optically anisotropic layer may be formed from a polymer film. The polymer film is formed from a polymer capable of developing birefringence. As the birefringent polymer film, those having excellent controllability of birefringence characteristics, transparency and heat resistance, and those having low photoelasticity are preferable. In this case, the polymer material to be used is not particularly limited as long as it is a polymer that can achieve uniform uniaxial orientation or biaxial orientation. , Norbornene polymer, polycarbonate polymer, polyarylate polymer, polyester polymer, aromatic polymer such as polysulfone, polyolefin such as polypropylene, cellulose acylate, or two or three of these polymers Examples thereof include a polymer obtained by mixing the above.

  The optical anisotropy of the polymer film is preferably obtained by uniaxial or biaxial stretching. Uniaxial stretching is preferably longitudinal uniaxial stretching using the difference in peripheral speed between two or more rolls, or tenter stretching in which both sides of the polymer film are gripped and stretched in the width direction. Further, biaxial optical anisotropy may be developed by stretching the polymer film in the longitudinal direction and the transverse direction. In addition, using two or more polymer films, the optical properties of the entire two or more films may satisfy the above conditions. The polymer film is preferably produced by a solvent cast method in order to reduce unevenness in birefringence. The thickness of the polymer film is preferably 20 to 400 nm, and most preferably 30 to 100 nm. A polarizing film using iodine, which is widely used, is manufactured by a continuous longitudinal uniaxial stretching process, and therefore has an absorption axis parallel to the longitudinal direction of the roll. Therefore, the long polarizing film stretched in a general longitudinal uniaxial direction and the long first optically anisotropic layer have the absorption axis of the polarizing film orthogonal to the slow axis of the first optically anisotropic layer. Thus, when laminating by roll-to-roll, it is preferable to use a transverse stretching machine so that the slow axis is orthogonal to the transport direction.

[Second optically anisotropic layer]
The liquid crystal display device of the present invention may have a second optically anisotropic layer. The second optically anisotropic layer is incorporated in the liquid crystal display device as a part of the laminated polarizing plate or as a single member. The optical characteristics of the second optically anisotropic layer are expressed as follows: Re = (nx−) using the in-plane refractive indices nx and ny (nx ≧ ny), the refractive index nz in the thickness direction, and the film thickness d. ny) × d in-plane retardation (Re) defined by 0 to 100 nm, more preferably 0 to 50 nm, and most preferably 0 to 20 nm. Further, the more preferable range of retardation (Rth) in the thickness direction defined by Rth = ((nx + ny) / 2−nz) × d varies depending on the optical characteristics of other optical members, and is particularly closer. Greatly varies depending on the Rth of the protective film (for example, triacetyl cellulose film) of the polarizing film located at the position. In order to effectively reduce light leakage in an oblique direction, it is −200 to −50 nm, more preferably −180 to −60 nm, and further preferably −160 to −70 nm.
The arrangement of the second optically anisotropic layer in the slow axis direction is not particularly limited, but when Re exceeds 20 nm, it is in a direction substantially parallel to the transmission axis of the polarizing film in the configuration of FIG. It is preferable that the thickness of the first optically anisotropic layer can be reduced, for example.

  As long as the second optical anisotropic layer has the optical characteristics, the material and form thereof are not particularly limited. For example, both a retardation film made of a birefringent polymer film and a retardation film having a retardation layer formed by applying or transferring a low-molecular or high-molecular liquid crystalline compound on a transparent support are used. be able to. Moreover, each can also be laminated | stacked and used.

  A retardation film made of a birefringent polymer film having the above optical characteristics is a method in which a heat-shrinkable film is laminated and heated to apply a predetermined tension while stretching the polymer film in the thickness direction of the film (Japanese Patent Laid-Open No. 2000). -206328 and JP-A-2000-304925) and a method of applying a vinylcarbazole polymer and drying it (JP-A-2001-091746). In addition, as a retardation layer formed from a liquid crystalline compound having the above optical properties, a cholesteric discotic liquid crystal compound or composition containing a chiral structural unit is fixed after its helical axis is aligned substantially perpendicular to the substrate. Examples thereof include a layer formed by forming a rod-like liquid crystal compound or composition having a positive refractive index anisotropy and a composition formed by orienting the substrate substantially perpendicularly to the substrate and then immobilizing it (for example, JP-A-6-6 331826 and Japanese Patent No. 2853064). The rod-like liquid crystal compound may be a low molecular compound or a high molecular compound. Furthermore, not only a single retardation layer but also a plurality of retardation layers can be laminated to form a second optical anisotropic layer exhibiting the above optical characteristics. Further, the second optical anisotropic layer may be configured so that the entire laminated body of the support and the retardation layer satisfies the optical characteristics. As the rod-like liquid crystal compound to be used, those that take a nematic liquid crystal phase, a smectic liquid crystal phase, or a lyotropic liquid crystal phase in a temperature range in which the orientation is fixed are preferably used. A liquid crystal exhibiting a smectic A phase and a B phase capable of obtaining uniform vertical alignment without fluctuation is preferable. These phases are preferable in that birefringence is larger than that of the nematic liquid crystal phase and the thickness of the film can be reduced. In particular, in the presence of an additive, a rod-like liquid crystalline compound that becomes a liquid crystal state in an appropriate orientation temperature range is formed by using a composition containing the additive and the rod-like liquid crystalline compound. Is also preferable.

  The second optically anisotropic layer included in the liquid crystal display device of the present invention may be formed from a composition containing a rod-like liquid crystalline compound. The rod-like liquid crystalline compound that can be used to form the second optically anisotropic layer, the method for fixing the alignment state, and materials other than the liquid crystal compound contained in the composition are the same as those in the first optical difference. It is the same as that which can be used for formation of an anisotropic layer.

  The retardation layer formed from the rod-like liquid crystalline compound is formed on the support with a coating liquid containing the rod-like liquid crystalline compound and, if desired, the following polymerization initiator, air interface vertical alignment agent and other additives. It can be formed by coating on the vertical alignment film, performing vertical alignment, and fixing the alignment state. When it is formed on a temporary support, it can also be produced by transferring the retardation layer onto the support. Furthermore, not only a single retardation layer but also a plurality of retardation layers may be laminated to constitute a second optical anisotropic layer exhibiting the above optical characteristics. Further, the second optical anisotropic layer may be configured so that the entire laminated body of the support and the retardation layer satisfies the optical characteristics.

  When the second optically anisotropic layer includes a retardation layer formed by fixing the alignment state of the rod-like liquid crystal compound, the rod-like liquid crystal compound is substantially vertically aligned to fix the state. It is preferable to use a retardation layer formed in this manner. Substantially perpendicular means that the angle formed by the film surface and the director of the rod-like liquid crystal compound is in the range of 70 ° to 90 °. These liquid crystalline compounds may be aligned obliquely or may be changed so that the inclination angle gradually changes (hybrid alignment). Even in the case of oblique alignment or hybrid alignment, the average inclination angle is preferably 70 ° to 90 °, more preferably 80 ° to 90 °, and most preferably 85 ° to 90 °.

[Vertical alignment film]
In order to align the liquid crystalline compound vertically on the alignment film side, it is important to reduce the surface energy of the alignment film. Specifically, the surface energy of the alignment film is lowered by the functional group of the polymer, thereby bringing the liquid crystalline compound into a standing state. As the functional group for reducing the surface energy of the alignment film, a hydrocarbon group having 10 or more fluorine atoms and carbon atoms is effective. In order to make a fluorine atom or a hydrocarbon group exist on the surface of the alignment film, it is preferable to introduce a fluorine atom or a hydrocarbon group into the side chain rather than the main chain of the polymer. The fluoropolymer preferably contains fluorine atoms in a proportion of 0.05 to 80% by mass, more preferably in a proportion of 0.1 to 70% by mass, and in a proportion of 0.5 to 65% by mass. More preferably, it is most preferable to contain in the ratio of 1-60 mass%. The hydrocarbon group is an aliphatic group, an aromatic group or a combination thereof. The aliphatic group may be cyclic, branched or linear. The aliphatic group is preferably an alkyl group (may be a cycloalkyl group) or an alkenyl group (may be a cycloalkenyl group). The hydrocarbon group may have a substituent that does not exhibit strong hydrophilicity, such as a halogen atom. The number of carbon atoms of the hydrocarbon group is preferably 10 to 100, more preferably 10 to 60, and most preferably 10 to 40. The main chain of the polymer preferably has a polyimide structure or a polyvinyl alcohol structure.

  Polyimide is generally synthesized by a condensation reaction of tetracarboxylic acid and diamine. A polyimide corresponding to a copolymer may be synthesized using two or more kinds of tetracarboxylic acids or two or more kinds of diamines. The fluorine atom or hydrocarbon group may be present in the repeating unit derived from tetracarboxylic acid, may be present in the repeating unit derived from diamine, or may be present in both repeating units. When introducing a hydrocarbon group into polyimide, it is particularly preferable to form a steroid structure in the main chain or side chain of the polyimide. The steroid structure present in the side chain corresponds to a hydrocarbon group having 10 or more carbon atoms, and has a function of vertically aligning the liquid crystalline compound. In this specification, the steroid structure is a cyclopentanohydrophenanthrene ring structure or a ring structure in which a part of the ring bond is a double bond in the range of an aliphatic ring (a range that does not form an aromatic ring). means.

  Further, as a means for vertically aligning the liquid crystalline compound, a method of mixing an organic acid with a polymer of polyvinyl alcohol, modified polyvinyl alcohol, or polyimide can be suitably used. Acids that can be used include carboxylic acids, sulfonic acids and amino acids. Examples of onium salts include quaternary onium salts such as ammonium salts (excluding NH4 +) and phosphonium salts. Specific examples include those described in paragraphs [0020] to [0044] of Japanese Patent Application No. 2004-3805. The mixing amount is preferably 0.1% by mass to 20% by mass and more preferably 0.5% by mass to 10% by mass with respect to the polymer.

  The saponification degree of the polyvinyl alcohol is preferably 70 to 100%, more preferably 80 to 100%. The polymerization degree of polyvinyl alcohol is preferably 100 to 5000.

  When aligning a rod-like liquid crystalline compound, the alignment film is preferably made of a polymer having a hydrophobic group as a functional group in the side chain. The specific type of functional group is determined according to the type of liquid crystal molecule and the required alignment state. For example, the modifying group of the modified polyvinyl alcohol can be introduced by copolymerization modification, chain transfer modification or block polymerization modification. Examples of modifying groups include hydrophilic groups (carboxylic acid groups, sulfonic acid groups, phosphonic acid groups, amino groups, ammonium groups, amide groups, thiol groups, etc.), hydrocarbon groups having 10 to 100 carbon atoms, fluorine atoms Substituted hydrocarbon groups, thioether groups, polymerizable groups (unsaturated polymerizable groups, epoxy groups, azirinidyl groups, etc.), alkoxysilyl groups (trialkoxy, dialkoxy, monoalkoxy) and the like can be mentioned. Specific examples of these modified polyvinyl alcohol compounds include, for example, paragraph numbers [0022] to [0145] in JP-A No. 2000-155216 and paragraph numbers [0018] to [0018] in JP-A No. 2002-62426. And the like described in [0022].

  The alignment film is formed by using a polymer having a side chain having a crosslinkable functional group bonded to the main chain or a polymer having a crosslinkable functional group on a side chain having a function of aligning liquid crystal molecules. When the retardation film is formed using a composition containing a polyfunctional monomer, the polymer in the alignment film and the polyfunctional monomer in the retardation film formed thereon can be copolymerized. As a result, a covalent bond is formed not only between the polyfunctional monomers but also between the alignment film polymers and between the polyfunctional monomer and the alignment film polymer, and the alignment film and the retardation film are firmly bonded. Therefore, the strength of the optical compensation sheet can be remarkably improved by forming the alignment film using a polymer having a crosslinkable functional group. The crosslinkable functional group of the alignment film polymer preferably contains a polymerizable group in the same manner as the polyfunctional monomer. Specific examples include those described in paragraphs [0080] to [0100] in JP-A-2000-155216.

  Apart from the crosslinkable functional group, the alignment film polymer can also be crosslinked using a crosslinking agent. Examples of the crosslinking agent include aldehydes, N-methylol compounds, dioxane derivatives, compounds that act by activating carboxyl groups, active vinyl compounds, active halogen compounds, isoxazole and dialdehyde starch. Two or more kinds of crosslinking agents may be used in combination. Specific examples include compounds described in paragraphs [0023] to [024] in JP-A-2002-62426. Aldehydes having high reaction activity, particularly glutaraldehyde are preferred.

  0.1-20 mass% is preferable with respect to a polymer, and, as for the addition amount of a crosslinking agent, 0.5-15 mass% is more preferable. The amount of the unreacted crosslinking agent remaining in the alignment film is preferably 1.0% by mass or less, and more preferably 0.5% by mass or less. By adjusting in this way, even if the alignment film is used for a long time in a liquid crystal display device or left in a high-temperature and high-humidity atmosphere for a long time, sufficient durability without occurrence of reticulation can be obtained.

  The alignment film can be basically formed by applying a composition containing the polymer and the crosslinking agent, which are alignment film forming materials, onto a transparent support, followed by drying by heating (crosslinking) and rubbing treatment. it can. As described above, the crosslinking reaction may be performed at any time after coating on the transparent support. When a water-soluble polymer such as polyvinyl alcohol is used as the alignment film forming material, the coating solution is preferably a mixed solvent of an organic solvent (eg, methanol) having a defoaming action and water. The ratio of water: methanol is preferably 0: 100 to 99: 1, and more preferably 0: 100 to 91: 9. Thereby, generation | occurrence | production of a bubble is suppressed and the defect of the alignment film and also the phase difference layer surface reduces remarkably.

  The alignment film is preferably applied by spin coating, dip coating, curtain coating, extrusion coating, rod coating, or roll coating. A rod coating method is particularly preferable. The film thickness after drying is preferably 0.1 to 10 μm. Heating and drying can be performed at 20 ° C to 110 ° C. In order to form sufficient cross-linking, 60 ° C to 100 ° C is preferable, and 80 ° C to 100 ° C is particularly preferable. The drying time can be 1 minute to 36 hours, preferably 1 minute to 30 minutes. The pH is preferably set to an optimum value for the crosslinking agent to be used. When glutaraldehyde is used, the pH is 4.5 to 5.5, and 5 is particularly preferable.

  The alignment film is preferably provided on the transparent support. The alignment film is used by crosslinking the polymer layer as described above. The rubbing treatment is preferably not performed for the vertical alignment of the rod-like liquid crystalline compound. In addition, after aligning a liquid crystalline compound using an alignment film, the liquid crystalline compound is fixed in the aligned state to form an optically anisotropic layer, and only the optically anisotropic layer is polymer film (or transparent support) It may be transferred onto the body).

[Air interface vertical alignment agent]
Usually, since the liquid crystalline compound has a property of being inclined and aligned on the air interface side, it is necessary to control the alignment of the liquid crystalline compound vertically on the air interface side in order to obtain a uniformly vertically aligned state. . For this purpose, a phase difference film is formed by adding a compound that is unevenly distributed on the air interface side and that has the effect of vertically aligning the liquid crystalline compound by its excluded volume effect or electrostatic effect to the liquid crystal coating liquid. It is preferable to do this.

  As the air interface alignment agent, compounds described in JP-A Nos. 2002-20363 and 2002-129162 can be used. Also, paragraph numbers [0072] to [0075] of Japanese Patent Application No. 2002-212100, paragraph numbers [0037] to [0039] of Japanese Patent Application No. 2002-262239, paragraphs of Japanese Patent Application No. 2003-91752 Nos. [0071] to [0078], paragraph numbers [0052] to [0054], [0065] to [0066], [0092] to [0094] of Japanese Patent Application No. 2003-119959, Japanese Patent Application No. 2003-330303 The matters described in paragraph numbers [0028] to [0030] of the specification and paragraph numbers [0087] to [0090] of Japanese Patent Application No. 2004-003804 can also be appropriately applied to the present invention. Moreover, by mix | blending these compounds, applicability | paintability is improved and generation | occurrence | production of a nonuniformity or a repellency is suppressed. The amount of the air interface alignment agent used in the liquid crystal coating liquid is preferably 0.05% by mass to 5% by mass. Moreover, when using a fluorine-type air interface aligning agent, it is preferable that it is 1 mass% or less.

  When the liquid crystal display device of the present invention includes a first optical anisotropic layer and a second optical anisotropic layer, the first optical anisotropic layer and the second optical anisotropic layer are respectively Are preferably laminated in a long state. In such a long laminate, when one optically anisotropic layer is formed from a liquid crystal compound, the other long optically anisotropic layer is used as a support and an alignment film is formed thereon. By forming an optically anisotropic layer made of a liquid crystal compound continuously, a long laminate can be obtained. Moreover, a long laminated body can be obtained by producing both optically anisotropic layers in a long form and then continuously bonding them by a roll-to-roll process.

[Polarizing film]
Examples of the polarizing film include an iodine polarizing film, a dye polarizing film using a dichroic dye, and a polyene polarizing film. The iodine polarizing film and the dye polarizing film are generally manufactured using a polyvinyl alcohol film. The absorption axis of the polarizing film corresponds to the stretching direction of the film. Accordingly, the polarizing film stretched in the longitudinal direction (transport direction) has an absorption axis parallel to the longitudinal direction, and the polarizing film stretched in the lateral direction (perpendicular to the transport direction) is perpendicular to the longitudinal direction. Has an absorption axis.

  The manufacturing method of the laminated polarizing plate included in the liquid crystal display device of the present invention includes a step in which the first polarizing film and the first optical anisotropic layer are successively laminated in a long state. In the laminated polarizing plate, the absorption axis of the first polarizing film and the slow axis of the first optical anisotropic layer are orthogonal. Therefore, when the polarizing film is produced by longitudinal stretching (having an absorption axis parallel to the longitudinal direction), the first optical anisotropic layer having a slow axis in a direction orthogonal to the longitudinal direction When the polarizing film is manufactured by transverse stretching (having an absorption axis in a direction orthogonal to the longitudinal direction), the first optical anisotropic having a slow axis parallel to the longitudinal direction By laminating the conductive layer, a long laminated polarizing plate can be obtained. The long laminated polarizing plate is cut according to the screen size of the liquid crystal display device used.

  The polarizing film generally has a protective film. In the present invention, when an optically anisotropic layer made of a liquid crystal compound is formed on a transparent support, the transparent support can function as a polarizing film. When the optically anisotropic layer is formed of a birefringent polymer film, the refractive polymer film can function as a protective film for the polarizing film. In the case of using a polarizing film protective film separately from them, it is preferable to use a cellulose ester film having high optical isotropy as the protective film.

[Protective film for polarizing film]
As the protective film for the polarizing film, a protective film having no absorption in the visible light region, a light transmittance of 80% or more, and a retardation based on birefringence is preferable. Specifically, the in-plane Re is preferably 0 to 20 nm, more preferably 0 to 10 nm, and most preferably 0 to 5 nm. Furthermore, the Rth in the thickness direction of the protective film (for example, 7b and 19a in FIG. 2) disposed on the liquid crystal cell side is preferably −60 to 60 nm, more preferably −40 to 40 nm, and −20 Most preferably, it is ˜20 nm. Further, from the viewpoint of reducing Rth in the thickness direction, the thickness of the protective film is preferably 60 μm or less, more preferably 50 μm or less, and most preferably 40 μm or less. However, when the protective film is composed of a plurality of layers in order to satisfy the above optical characteristics, the preferred range of thickness is not limited to this range. The optical properties of the other protective film (for example, 7a and 19b in FIGS. 2 and 3) are not particularly limited, but in general, Re is 0 to 20 nm and Rth is −60 to 60 nm. Preferably, the thickness is 10 to 120 μm.

Any film having this characteristic can be preferably used, but from the viewpoint of durability of the polarizing film, cellulose acylate or norbornene-based film is more preferable.
As the norbornene-based polymer, norbornene and its derivatives, tetracyclododecene and its derivatives, dicyclopentadiene and its derivatives, methanotetrahydrofluorene and its monomers as a main component of a norbornene-based monomer polymer, Ring-opening polymer of norbornene monomer, ring-opening copolymer of norbornene monomer and other monomer capable of ring-opening copolymerization, addition polymer of norbornene monomer, copolymerizable with norbornene monomer Examples include addition copolymers with other monomers and hydrogenated products thereof. Among these, from the viewpoints of heat resistance, mechanical strength, and the like, a ring-opening polymer hydride of a norbornene monomer is most preferable. The molecular weight of the norbornene-based polymer, the polymer of the monocyclic olefin or the polymer of the cyclic conjugated diene is appropriately selected according to the purpose of use, but the cyclohexane solution (toluene solution if the polymer resin does not dissolve) The polyisoprene or polystyrene-converted weight average molecular weight measured by gel permeation chromatography is usually 5,000 to 500,000, preferably 8,000 to 200,000, more preferably 10,000 to 100,000. When the thickness is within the range, the mechanical strength of the film and the moldability are highly balanced, which is preferable.

  The cellulose acylate is not particularly limited, and the acyl group may be an aliphatic group or an allyl group. They are, for example, alkyl carbonyl esters, alkenyl carbonyl esters, aromatic carbonyl esters, aromatic alkyl carbonyl esters, etc. of cellulose, each of which may further have a substituted group, and an ester having a total carbon number of 22 or less. Groups are preferred. These preferred cellulose acylates include acyl groups having a total carbon number of 22 or less in the ester moiety (for example, acetyl, propionyl, butyroyl, barrel, heptanoyl, octanoyl, decanoyl, dodecanoyl, tridecanoyl, hexadecanoyl, octadecanoyl, etc. ), Arylcarbonyl groups (acrylic, methacrylic, etc.), allylcarbonylkis (benzoyl, naphthaloyl etc.) and cinnamoyl groups. Among these, cellulose acetate, cellulose acetate propionate, cellulose acetate butyrate, cellulose acetate stearate, cellulose acetate benzoate, etc. are not particularly limited in the case of mixed esters, but preferably acetate is the total ester. It is preferable that it is 30 mol% or more.

  Among these, cellulose acylate is preferred, and photographic grades are particularly preferred, and commercially available photographic grades can be obtained with satisfactory quality such as viscosity average degree of polymerization and substitution degree. Manufacturers of photographic grade cellulose triacetate include Daicel Chemical Industries, Ltd. (for example, LT-20, 30, 40, 50, 70, 35, 55, 105, etc.), Eastman Kodak Company (for example, CAB-551). 0.01, CAB-551-0.02, CAB-500-5, CAB-381-0.5, CAB-381-02, CAB-381-20, CAB-321-0.2, CAP-504 0.2, CAP-482-20, CA-398-3, etc.), Coatles, Hoechst, etc., any of which can use photographic grade cellulose acylate. In addition, a plasticizer, a surfactant, a retardation modifier, a UV absorber, and the like can be mixed for the purpose of controlling the mechanical properties and optical properties of the film (reference material: Japanese Patent Application Laid-Open No. 2002-277632). Gazette, JP-A-2002-182215)

As a method of forming the transparent resin into a sheet or film, for example, either a hot melt molding method or a solution casting method can be used. The heat-melt molding method can be further classified into an extrusion molding method, a press molding method, an inflation molding method, an injection molding method, a blow molding method, a stretch molding method, etc. Among these methods, mechanical strength, surface In order to obtain a film excellent in accuracy and the like, the extrusion molding method, the inflation molding method, and the press molding method are preferable, and the extrusion molding method is most preferable. The molding conditions are appropriately selected depending on the purpose of use and the molding method. In the case of the heat-melt molding method, the cylinder temperature is preferably set in the range of preferably 100 to 400 ° C, more preferably 150 to 350 ° C. The thickness of the sheet or film is preferably 10 to 300 μm, more preferably 30 to 200 μm.
When the glass transition temperature of the transparent resin is defined as Tg, the stretching of the sheet or film is preferably in a temperature range of Tg-30 ° C to Tg + 60 ° C, more preferably in a temperature range of Tg-10 ° C to Tg + 50 ° C. In at least one direction, the stretching ratio is preferably 1.01 to 2 times. The stretching direction may be at least one direction, but when the sheet is obtained by extrusion, the direction is preferably the mechanical flow direction (extrusion direction) of the resin. A free shrink uniaxial stretching method, a fixed width uniaxial stretching method, a biaxial stretching method, and the like are preferable. The optical characteristics can be controlled by controlling the draw ratio and the heating temperature.

  As a method for reducing the Rth of a cellulose acylate film, it is effective to mix a compound having a non-planar structure into the film. Moreover, the method of Unexamined-Japanese-Patent No. 11-246704, Unexamined-Japanese-Patent No. 2001-247717, Japanese Patent Application No. 2003-379975, etc. are mentioned. Rth can also be reduced by reducing the thickness of the cellulose acylate film.

  A polarizing plate protective film having negative optical characteristics for Rth can be obtained by a method of stretching a polymer film in the thickness direction of the film (e.g., Japanese Patent Application Laid-Open No. 2000-162436) or by applying a vinylcarbazole polymer and drying it. It can be easily formed by a method (eg, Japanese Patent Application Laid-Open No. 2001-091746). In addition, the protective film may contain a liquid crystal material, and for example, may contain a retardation layer formed from a liquid crystalline compound having a negative optical characteristic for Rth. The retardation layer is a layer formed by fixing a cholesteric discotic liquid crystal compound or composition containing a chiral structural unit after its helical axis is aligned substantially perpendicular to the substrate and has a positive refractive index anisotropy. Examples thereof include a layer formed by orienting the rod-like liquid crystal compound or composition of the present invention on the substrate and then fixing it to the substrate (see, for example, JP-A-6-331826 and Japanese Patent No. 2853064). The rod-like liquid crystal compound may be a low molecular compound or a high molecular compound. Furthermore, it is possible to form a protective film that exhibits not only one retardation layer but also a plurality of retardation layers to exhibit optical characteristics with negative Rth. Further, the protective layer may be configured so that the entire laminate of the support and the retardation layer satisfies a negative optical characteristic of Rth. As the rod-like liquid crystal compound to be used, those that take a nematic liquid crystal phase, a smectic liquid crystal phase, or a lyotropic liquid crystal phase in a temperature range in which the orientation is fixed are preferably used. A liquid crystal exhibiting a smectic A phase and a B phase capable of obtaining uniform vertical alignment without fluctuation is preferable. In addition, in the presence of an additive, the rod-like liquid crystalline compound that is in the liquid crystal state in an appropriate orientation temperature range may be formed using a composition containing the additive and the rod-like liquid crystalline compound. preferable.

  The features of the present invention will be described more specifically with reference to examples and comparative examples. The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples shown below.

[Example 1]
<Preparation of retardation plate 1>
(Formation of first optically anisotropic layer) The following acrylic acid copolymer and triethylamine (neutralizing agent) were dissolved in a methanol / water mixed solvent (mass ratio = 30/70) to prepare a 4% by mass solution. Prepared. While transporting a cellulose acetate film in the form of a saponified surface (Fujitac TD80UF, manufactured by Fuji Photo Film Co., Ltd., length 500 m, thickness 80 μm, Re = 3 nm, Rth = 45 nm) The coating was continuously performed using a bar coater. The coating layer was heated at 120 ° C. for 5 minutes and dried to form a 1 μm thick layer. While the rolled cellulose acetate film provided with the coating layer was transported, the surface of the coating layer was continuously rubbed in the longitudinal direction (transport direction) to form an alignment film.

  On the alignment film, a coating solution having the following composition was continuously applied using a bar coater. The coating layer was heated at 100 ° C. for 1 minute to align the rod-like liquid crystal molecules, and then irradiated with ultraviolet rays to polymerize the rod-like liquid crystal molecules to fix the alignment state.

Composition of coating solution for the first optically anisotropic layer ―――――――――――――――――――――――――――――――――
The following rod-like liquid crystal compound 38.4% by weight
The following sensitizer 0.38% by weight
The following photopolymerization initiator 1.15% by weight
The following air interface horizontal alignment agent 0.06 wt%
Methyl ethyl ketone 60.0% by weight
―――――――――――――――――――――――――――――――――

  Using an automatic birefringence meter (KOBRA-21ADH, manufactured by Oji Scientific Instruments Co., Ltd.), the dependency of Re on the light incident angle of the film on which the first optical anisotropic layer was formed was measured and measured in advance. By subtracting the contribution of the cellulose acetate film, the optical properties of only the first optical anisotropic layer were calculated. Re was 94 nm, Rth was 47 nm, the average tilt angle of the long axis of the rod-like liquid crystal molecules with respect to the layer plane was 0 °, and the film was aligned parallel to the film plane. The rod-like liquid crystalline molecules were oriented so that the major axis direction was orthogonal to the longitudinal direction of the roll cellulose acetate film (that is, the slow axis direction of the first optically anisotropic layer was the roll cellulose acetate. It was orthogonal to the longitudinal direction of the film).

(Formation of second optically anisotropic layer)
After diluting a commercially available vertical alignment film (JALS-204R, manufactured by JSR Corporation) 1: 1 with methyl ethyl ketone on the first optically anisotropic layer formed on the roll-like cellulose acetate film, the wire 2.4 ml / m ^{2 was} applied with a bar coater and immediately dried with 120 ° C. hot air for 120 seconds.

  On the alignment film, a coating solution having the following composition was continuously applied using a bar coater. The coating layer was heated at 100 ° C. for 1 minute to align the rod-like liquid crystal molecules, and then irradiated with ultraviolet rays to polymerize the rod-like liquid crystal molecules to fix the alignment state.

Composition of the coating solution for the second optically anisotropic layer ―――――――――――――――――――――――――――――――
38.4% by weight of the above rod-shaped liquid crystal compound
The above sensitizer 0.38% by weight
The above photopolymerization initiator 1.15% by weight
The following air interface vertical alignment agent 0.03% by weight
Methyl ethyl ketone 60.0% by weight
―――――――――――――――――――――――――――――――

  The dependency of Re on the light incident angle of the film in which the first optical anisotropic layer and the second optical anisotropic layer are laminated is measured, and the first optical anisotropic layer and the cellulose acetate film measured in advance are measured. By subtracting the contribution, the optical characteristics of only the second optical anisotropic layer were calculated. Re was 0 nm, Rth was −94 nm, the average tilt angle of the long axis of the rod-like liquid crystal molecules with respect to the layer plane was 90 °, and it was aligned perpendicular to the film plane.

  As described above, a retardation plate having a length of 500 m in which the first optically anisotropic layer and the second optically anisotropic layer were laminated in this order on a roll-like cellulose acetate film was obtained. Subsequently, the surface of the cellulose acetate film opposite to the surface on which the first optical anisotropic layer and the second optical anisotropic layer were formed was continuously saponified, and this was used as the retardation film 1. .

<Preparation of laminated polarizing plate 1>
A roll-shaped polyvinyl alcohol film having a thickness of 80 μm continuously dyed in an aqueous iodine solution was stretched 5 times in the transport direction and dried to obtain a polarizing film having a length of 500 m. One surface of the polarizing film was subjected to saponification treatment on the other surface of the retardation plate 1 on which the first optical anisotropic layer and the second optical anisotropic layer were not laminated. Cellulose triacetate film (Fujitac TD80UF, manufactured by Fuji Photo Film Co., Ltd.) was continuously bonded using a polyvinyl alcohol adhesive to produce a laminated polarizing plate 1 having a length of 500 m. The absorption axis of the polarizing film was parallel to the longitudinal direction of the film, and the slow axis of the first optically anisotropic layer was orthogonal to the longitudinal direction of the film.
The roll-shaped laminated polarizing plate 1 was cut from an arbitrary portion to obtain 10 laminated polarizing plates 1 having a size of 20 cm × 20 cm. The cutting was performed so that one side was parallel to the absorption axis of the polarizing film (perpendicular to the slow axis of the first optical anisotropic layer).

<Preparation of polarizing plate A>
A roll-shaped polyvinyl alcohol film having a thickness of 80 μm continuously dyed in an aqueous iodine solution was stretched 5 times in the transport direction and dried to obtain a polarizing film having a length of 500 m. Saponified cellulose triacetate film (Fujitac T40UZ, manufactured by Fuji Photo Film Co., Ltd., thickness 40 μm, Re = 1 nm, Rth = 35 nm) was continuously applied to both surfaces of this polarizing film using a polyvinyl alcohol adhesive. And a polarizing plate A having a length of 500 m was produced. The absorption axis of the polarizing film was parallel to the film longitudinal direction.
The roll-shaped polarizing plate A was cut from an arbitrary portion to obtain 10 polarizing plates A having a size of 20 cm × 20 cm. The cutting was performed so that one side was parallel to the absorption axis of the polarizing film.

<Production of liquid crystal display device 1>
As shown in FIG. 1, electrodes (2 and 3 in FIG. 1) are arranged on one glass substrate so that the distance between adjacent electrodes is 20 μm, and a polyimide film is used as an alignment film on it. A rubbing treatment was performed. The rubbing process was performed in the direction 4 shown in FIG. A polyimide film was provided on one surface of a separately prepared glass substrate, and a rubbing treatment was performed to obtain an alignment film. The two glass substrates are stacked and bonded so that the alignment films face each other, the distance between the substrates (gap; d) is 3.9 μm, and the rubbing directions of the two glass substrates are parallel. A nematic liquid crystal composition having a refractive index anisotropy (Δn) of 0.0769 and a dielectric anisotropy (Δε) of 4.5 was sealed to produce an IPS mode liquid crystal cell. The value of d · Δn of the liquid crystal layer was 300 nm.
In one of the IPS mode liquid crystal cells prepared above, the laminated polarizing plate 1 produced as described above is subjected to the second so that the absorption axis thereof is orthogonal to the rubbing direction of the liquid crystal cell (the slow axis direction of the liquid crystal molecules during black display). The optically anisotropic layer was attached so as to be on the liquid crystal cell side. Subsequently, the produced polarizing plate A was attached to the other side of the liquid crystal cell in a crossed Nicol arrangement, and the liquid crystal display device 1 was produced.

  Ten liquid crystal display devices 1 were produced, white display and black display were performed, and the luminance ratio in the front direction was determined as the contrast ratio. A product having 90% or less with respect to the contrast ratio of the liquid crystal display device in which only the polarizing plate was bonded without including the retardation plate was regarded as a defective product. Of the ten liquid crystal display devices 1, the number of defective products generated was zero. Furthermore, when the leakage light in the left diagonal direction of 60 ° was measured, the average value of 10 non-defective products was 0.09%.

[Example 2]
<Preparation of cellulose acetate film 1>
The following composition was put into a mixing tank and stirred while heating to dissolve each component to prepare a cellulose acetate solution.
<Composition of cellulose acetate solution A>
―――――――――――――――――――――――――――――――――――
Cellulose acetate with a degree of substitution of 2.86 100 parts by weight Triphenyl phosphate (plasticizer) 7.8 parts by weight Biphenyl diphenyl phosphate (plasticizer) 3.9 parts by weight methylene chloride (first solvent) 300 parts by weight methanol (second solvent) ) 54 parts by mass 1-butanol 11 parts by mass ―――――――――――――――――――――――――――――――――――

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

  A dope was prepared by adding 40 parts by mass of the additive solution B to 477 parts by mass of the cellulose acetate solution A and stirring sufficiently. The dope was cast from a casting port onto a drum cooled to 0 ° C. The solvent content is peeled off at 70% by mass, both ends in the width direction of the film are fixed with a pin tenter (the pin tenter described in FIG. 3 of JP-A-4-1009), and the solvent content is 3-5% by mass. In this state, the film was dried while maintaining an interval at which the stretching ratio in the transverse direction (direction perpendicular to the machine direction) was 3%. Then, it dried further by conveying between the rolls of the heat processing apparatus, and produced the cellulose acetate film 1 of thickness 80micrometer and length 500m. The cellulose acetate film 1 had an Re of 1 nm and an Rth of 6 nm.

<Preparation of retardation plate 2>
A saponification treatment is performed on the surface of the roll-shaped cellulose acetate film 1 produced above, and an alignment film is formed in the same manner as when the first optical anisotropic layer is formed in Example 1 on the surface. A first optically anisotropic layer made of a rod-like liquid crystal was formed. The optical characteristics of only the first optically anisotropic layer were calculated in the same manner as in Example 1. As a result, Re was 140 nm, Rth was 70 nm, and the average tilt angle with respect to the layer plane of the long axis of rod-like liquid crystal molecules was 0 °. It was oriented parallel to the film plane. The rod-like liquid crystalline molecules were oriented so that the major axis direction was orthogonal to the longitudinal direction of the roll cellulose acetate film 1 (that is, the slow axis direction of the first optically anisotropic layer was the roll cellulose. It was orthogonal to the longitudinal direction of the acetate film 1).

  On the first optically anisotropic layer on the roll-shaped cellulose acetate film 1 produced above, an alignment film was formed in the same manner as when the second optically anisotropic layer was formed in Example 1. Further, a second optical anisotropic layer made of rod-like liquid crystal was formed. When the optical characteristics of only the second optically anisotropic layer were measured in the same manner as in Example 1, Re was 0 nm, Rth was -100 nm, and the average tilt angle with respect to the layer plane of the major axis of the rod-like liquid crystal molecules was 90. And was oriented perpendicular to the film plane.

  As described above, a retardation plate having a length of 500 m in which the first optically anisotropic layer and the second optically anisotropic layer were laminated in this order on the roll-shaped cellulose acetate film 1 was obtained. Subsequently, the surface of the cellulose acetate film opposite to the surface on which the first optical anisotropic layer and the second optical anisotropic layer were formed was continuously saponified, and this was used as the retardation film 2. .

<Preparation of laminated polarizing plate 2>
A roll-shaped polyvinyl alcohol film having a thickness of 80 μm continuously dyed in an aqueous iodine solution was stretched 5 times in the transport direction and dried to obtain a polarizing film having a length of 500 m. One surface of the polarizing film was subjected to saponification treatment on the other surface of the retardation plate 2 on which the first optical anisotropic layer and the second optical anisotropic layer were not laminated. Cellulose triacetate film (Fujitac TD80UF, manufactured by Fuji Photo Film Co., Ltd.) was continuously bonded using a polyvinyl alcohol adhesive to produce a laminated polarizing plate 2 having a length of 500 m. The absorption axis of the polarizing film was parallel to the longitudinal direction of the film, and the slow axis of the first optically anisotropic layer was orthogonal to the longitudinal direction of the film.
The roll-shaped laminated polarizing plate 2 was cut from an arbitrary portion to obtain 10 laminated polarizing plates 2 having a size of 20 cm × 20 cm. The cutting was performed so that one side was parallel to the absorption axis of the polarizing film (perpendicular to the slow axis of the first optical anisotropic layer).

<Preparation of polarizing plate B>
A roll-shaped polyvinyl alcohol film having a thickness of 80 μm continuously dyed in an aqueous iodine solution was stretched 5 times in the transport direction and dried to obtain a polarizing film having a length of 500 m. A saponified cellulose acetate film 1 was continuously bonded to both surfaces of this polarizing film using a polyvinyl alcohol-based adhesive to prepare a polarizing plate B having a length of 500 m. The absorption axis of the polarizing film was parallel to the film longitudinal direction.
The roll-shaped polarizing plate B was cut from an arbitrary portion to obtain 10 polarizing plates B having a size of 20 cm × 20 cm. The cutting was performed so that one side was parallel to the absorption axis of the polarizing film.

<Production of liquid crystal display device 2>
One of the IPS mode liquid crystal cells produced in the same manner as in Example 1, the absorption axis of the produced laminated polarizing plate 2 is orthogonal to the rubbing direction of the liquid crystal cell (the slow axis direction of the liquid crystal molecules during black display). The second optically anisotropic layer was attached so as to be on the liquid crystal cell side. Subsequently, the prepared polarizing plate B was attached to the other side of the liquid crystal cell in a crossed Nicol arrangement, and the liquid crystal display device 2 was manufactured.

  Ten liquid crystal display devices 2 were produced, and the number of defective products examined in the same manner as in Example 1 was zero. Furthermore, when the leaked light in the left oblique direction of 60 ° was measured, the average value of 10 non-defective products was 0.06%.

[Example 3]
<Preparation of retardation plate 3>
A first optically anisotropic layer made of a polymer film was formed as follows. A roll-shaped norbornene-based polymer film (Arton, manufactured by JSR Co., Ltd.) having a thickness of 100 μm is continuously stretched at a temperature of 180 ° C. using a horizontal uniaxial tenter stretching machine to obtain an Arton film 1 of 500 m in length. It was. When the optical properties of this arton film 1 were measured, Re was 140 nm, Rth was 70 nm, and the optical axis was parallel to the film plane. Further, the slow axis direction of the ARTON film 1 was orthogonal to the longitudinal direction of the roll film.

A corona discharge treatment is continuously applied to the surface of the roll-shaped arton film 1 produced above, and an alignment film is formed thereon in the same manner as when the second optically anisotropic layer is formed in Example 2. Further, a second optical anisotropic layer made of rod-like liquid crystal was formed. When the optical characteristics of only the second optically anisotropic layer were measured in the same manner as in Example 1, Re was 0 nm, Rth was -100 nm, and the average tilt angle with respect to the layer plane of the major axis of the rod-like liquid crystal molecules was 90. And was oriented perpendicular to the film plane. As described above, a retardation plate 3 having a length of 500 m in which the second optically anisotropic layer was laminated on the arton film 1 as the first optically anisotropic layer was obtained.
<Preparation of laminated polarizing plate 3>
The roll-like retardation plate 3 produced above and the roll-like polarizing plate B produced in Example 2 were continuously bonded using an optically isotropic acrylic adhesive, and the length of 500 m A laminated polarizing plate 3 was obtained. In addition, it bonded together so that Arton film 1 (surface in which the 2nd optically anisotropic layer was not laminated | stacked) might become a polarizing plate side. The absorption axis of the polarizing film was parallel to the longitudinal direction of the film, and the slow axis of the first optically anisotropic layer was orthogonal to the longitudinal direction of the film.
The roll-shaped laminated polarizing plate 3 was cut from an arbitrary portion to obtain 10 laminated polarizing plates 3 having a size of 20 cm × 20 cm. The cutting was performed so that one side was parallel to the absorption axis of the polarizing film (perpendicular to the slow axis of the first optical anisotropic layer).

<Production of liquid crystal display device 3>
One of the IPS mode liquid crystal cells produced in the same manner as in Example 1, the absorption axis of the produced laminated polarizing plate 3 is orthogonal to the rubbing direction of the liquid crystal cell (the slow axis direction of the liquid crystal molecules during black display). The second optically anisotropic layer was attached so as to be on the liquid crystal cell side. Subsequently, the produced polarizing plate B was attached to the other side of the liquid crystal cell in a crossed Nicol arrangement, and the liquid crystal display device 3 was produced.

  Ten liquid crystal display devices 3 were produced, and the number of defective products examined in the same manner as in Example 1 was zero. Furthermore, when the leaked light in the left oblique direction of 60 ° was measured, the average value of 10 non-defective products was 0.06%.

[Example 4]
<Preparation of retardation plate 4>
A first optically anisotropic layer made of a polymer film was formed as follows. A roll-shaped norbornene-based polymer film (Arton, manufactured by JSR Co., Ltd.) having a thickness of 100 μm was continuously stretched at a temperature of 180 ° C. using a longitudinal uniaxial stretching machine to obtain an Arton film 2 having a length of 500 m. . When the optical properties of this arton film 2 were measured, Re was 140 nm, Rth was 70 nm, and the optical axis was parallel to the film plane. Further, the slow axis direction of Arton Film 2 was parallel to the longitudinal direction of the roll film.

The surface of the roll-shaped arton film 2 produced above is continuously subjected to corona discharge treatment, and an alignment film is formed thereon in the same manner as when the second optical anisotropic layer is formed in Example 2. Further, a second optical anisotropic layer made of rod-like liquid crystal was formed. When the optical characteristics of only the second optically anisotropic layer were measured in the same manner as in Example 1, Re was 0 nm, Rth was -100 nm, and the average tilt angle with respect to the layer plane of the major axis of the rod-like liquid crystal molecules was 90. And was oriented perpendicular to the film plane. As described above, the retardation plate 4 having a length of 500 m in which the second optically anisotropic layer was laminated on the arton film 2 as the first optically anisotropic layer was obtained.
<Preparation of laminated polarizing plate 4>
A rolled polyvinyl alcohol film having a thickness of 80 μm continuously dyed in an aqueous iodine solution was stretched using a horizontal uniaxial tenter stretching machine and dried to obtain a polarizing film having a length of 500 m. On one surface of the polarizing film, the arton film 2 side (the surface on which the second optical anisotropic layer is not laminated) of the produced retardation plate 4 is optically isotropic acrylic pressure-sensitive adhesive. At the same time, saponified cellulose triacetate film (Fujitac TD80UF, manufactured by Fuji Photo Film Co., Ltd.) is applied to the other surface of the polarizing film using a polyvinyl alcohol adhesive. The laminated polarizing plate 4 having a length of 500 m was prepared by continuously bonding. The absorption axis of the polarizing film was perpendicular to the longitudinal direction of the film, and the slow axis of the first optically anisotropic layer was parallel to the longitudinal direction of the film.
The roll-shaped laminated polarizing plate 4 was cut from an arbitrary portion to obtain 10 laminated polarizing plates 4 having a size of 20 cm × 20 cm. The cutting was performed so that one side was parallel to the absorption axis of the polarizing film (perpendicular to the slow axis of the first optical anisotropic layer).
<Preparation of polarizing plate C>
A roll-shaped polyvinyl alcohol film having a thickness of 80 μm continuously dyed in an aqueous iodine solution was stretched 5 times in the transport direction and dried to obtain a polarizing film having a length of 500 m. Saponification treatment (Fujitac TD80UF, manufactured by Fuji Photo Film Co., Ltd.) was continuously bonded to one surface of this polarizing film using a polyvinyl alcohol adhesive to prepare a polarizing plate C having a length of 500 m. The absorption axis of the polarizing film was parallel to the film longitudinal direction.
The roll-shaped polarizing plate C was cut from an arbitrary portion to obtain 10 polarizing plates C each having a size of 20 cm × 20 cm. The cutting was performed so that one side was parallel to the absorption axis of the polarizing film.

<Production of liquid crystal display device 4>
One of the IPS mode liquid crystal cells produced in the same manner as in Example 1, the absorption axis of the produced laminated polarizing plate 4 is perpendicular to the rubbing direction of the liquid crystal cell (the slow axis direction of the liquid crystal molecules during black display). The second optically anisotropic layer was attached so as to be on the liquid crystal cell side. Subsequently, the prepared polarizing plate C is attached to the other side of the liquid crystal cell using an acrylic pressure-sensitive adhesive so that the side where the cellulose triacetate film is not attached is the liquid crystal cell side in a crossed Nicol arrangement. A liquid crystal display device 4 was produced.

  Ten liquid crystal display devices 4 were produced, and the number of defective products examined in the same manner as in Example 1 was zero. Furthermore, when the leakage light in the direction of 60 ° to the left was measured, the average value of 10 non-defective products was 0.05%.

[Comparative Example 1]
<Preparation of laminated polarizing plate 5>
The roll-shaped phase difference plate 4 produced in Example 4 was cut from an arbitrary portion to obtain 10 phase difference plates 4 having a size of 20 cm × 20 cm. The cutting was performed so that one side was parallel to the slow axis of the first optically anisotropic layer. Subsequently, 10 commercially available polarizing plates (HLC2-5618, manufactured by Sanlitz Co., Ltd.) were cut into a size of 20 cm × 20 cm. The cutting was performed so that one side was parallel to the absorption axis of the polarizing film. The retardation plate 4 and the polarizing plate are bonded together so that the slow axis of the first optically anisotropic layer of the retardation plate 4 and the absorption axis of the polarizing plate are perpendicular to each other to obtain a laminated polarizing plate 5. A sheet was produced.
<Production of liquid crystal display device 5>
One of the IPS mode liquid crystal cells produced in the same manner as in Example 1, the absorption axis of the produced laminated polarizing plate 5 is orthogonal to the rubbing direction of the liquid crystal cell (the slow axis direction of the liquid crystal molecules during black display). The second optically anisotropic layer was attached so as to be on the liquid crystal cell side. Subsequently, on the other side of the liquid crystal cell, a commercially available polarizing plate (HLC2-5618, Sanlitz Co., Ltd.) having a size of 20 cm × 20 cm and having one side parallel to the absorption axis of the polarizing film. Manufactured) was pasted in a crossed Nicol arrangement to produce a liquid crystal display device 5.

  Ten liquid crystal display devices 5 were produced, and the number of defective products examined in the same manner as in Example 1 was three. Furthermore, when the leakage light in the left oblique direction of 60 ° was measured, the average value of 7 non-defective products was 0.17%.

[Comparative Example 2]
<Production of liquid crystal display device 6>
Commercially available polarizing plates (HLC2-5618, HLC2-5618, cut into a size of 20 cm × 20 cm and having one side parallel to the absorption axis of the polarizing film in both IPS mode liquid crystal cells produced in the same manner as in Example 1. The liquid crystal display device 6 was produced by pasting with a crossed Nicol arrangement.

  Ten liquid crystal display devices 6 were produced, and the number of defective products examined in the same manner as in Example 1 was zero. Furthermore, when the leakage light in the 60 ° left oblique direction was measured, the average value of 10 non-defective products was 0.55%.

It is the schematic which shows the pixel area example of the liquid crystal display device of this invention. It is the schematic which shows the example of the liquid crystal display device of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Liquid crystal element pixel area 2 Pixel electrode 3 Display electrode 4 Rubbing direction 5a, 5b Director of liquid crystal compound at the time of black display 6a, 6b Director of liquid crystal compound at the time of white display 7a, 7b, 19a, 19b Protective film for polarizing film 8, 20 Polarizing film 9, 21 Polarization transmission axis of polarizing film 10 First optical anisotropic layer 11 Slow axis 12 of first optical anisotropic layer Second optical anisotropic layer 13, 17 Cell substrate 14, 18 Cell substrate rubbing direction 15 Liquid crystal layer 16 Slow axis direction of liquid crystal layer

Claims (16)

A laminated polarizing plate obtained by cutting a long laminated body in which a first polarizing film and a first optically anisotropic layer are continuously bonded in a long state into a predetermined size, and a first substrate A liquid crystal layer and a second substrate arranged in this order, wherein the absorption axis of the first polarizing film and the slow axis of the first optically anisotropic layer are substantially The liquid crystal molecules of the liquid crystal layer are aligned substantially parallel to the surfaces of the pair of substrates during black display, and the slow axis of the first optically anisotropic layer is A liquid crystal display device that is substantially parallel to the slow axis direction of liquid crystal molecules during black display. The absorption axis of the first polarizing film is substantially parallel to the long longitudinal direction, and the slow axis of the first optically anisotropic layer is substantially parallel to the long longitudinal direction. The liquid crystal display device according to claim 1, comprising a laminated polarizing plate formed by cutting a long laminate that is orthogonal to a predetermined size. The absorption axis of the first polarizing film is substantially perpendicular to the long longitudinal direction, and the slow axis of the first optical anisotropic layer is substantially parallel to the long longitudinal direction. The liquid crystal display device according to claim 1, further comprising a laminated polarizing plate formed by cutting a long laminated body parallel to the substrate into a predetermined size. When the in-plane retardation (Re) and thickness direction retardation (Rth) of the optically anisotropic layer are defined by the following formulas (1) and (2), respectively, the first optically anisotropic layer The liquid crystal display device according to claim 1, wherein Re is 60 to 200 nm and Rth is 30 to 100 nm.
Re = (nx−ny) × d (1)
Rth = {(nx + ny) / 2−nz} × d (2)
(In the formula, nx and ny are the refractive indexes in two directions orthogonal to each other in the plane of the optically anisotropic layer (nx ≧ ny), nz is the refractive index in the thickness direction, and d is the thickness of the optically anisotropic layer ( nm).) 5. The liquid crystal display device according to claim 1, wherein the first optical anisotropic layer includes a layer that exhibits optical anisotropy by aligning a liquid crystalline compound. 6. 5. The liquid crystal display device according to claim 1, wherein the first optically anisotropic layer includes a layer that exhibits optical anisotropy by stretching a polymer film. A second optical anisotropic layer is included between the first polarizing film and the first substrate, the Re of the second optical anisotropic layer is 0 to 50 nm, and the Rth is −200 to − The liquid crystal display device according to claim 1, wherein the liquid crystal display device is 50 nm. The liquid crystal display device according to claim 7, wherein the first polarizing film, the first optical anisotropic layer, the second optical anisotropic layer, and the first substrate are laminated in this order. After laminating the laminate of the first polarizing film, the first optical anisotropic layer, and the second optical anisotropic layer in a long state to form a laminate, The liquid crystal display device according to claim 7 or 8, comprising a laminated polarizing plate cut into a size. 10. The liquid crystal display device according to claim 7, wherein the second optical anisotropic layer includes a layer that exhibits optical anisotropy by aligning a liquid crystal compound. 11. The liquid crystal display device according to claim 7, wherein the second optically anisotropic layer includes a layer in which optical anisotropy is expressed by stretching a polymer film. Further including one or more optical anisotropic layers between the first polarizing film and the first optical anisotropic layer, and the total Re of the one or more optical anisotropic layers is 0 to 20 nm. The liquid crystal display device according to claim 1, wherein Rth is −60 to 60 nm. Any one of the substantially optically isotropic adhesive layer or pressure-sensitive adhesive layer is included between the first polarizing film and the first optically anisotropic layer. 2. A liquid crystal display device according to item 1. The liquid crystal display device according to claim 1, further comprising a second polarizing film on an outer side of the second substrate. The liquid crystal according to claim 14, further comprising: a pair of protective films arranged with the second polarizing film interposed therebetween, wherein Rth of the protective film on the side close to the liquid crystal layer is −60 to 60 nm. Display device. The liquid crystal display device according to claim 14, wherein only a substantially optically isotropic adhesive layer or pressure-sensitive adhesive layer is included between the second substrate and the second polarizing film.

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