JP2005222004A - Liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an IPS (in-plane switching) liquid crystal display in which not only the display quality but the viewing angle is significantly improved by a simple structure. <P>SOLUTION: The liquid crystal display comprises, a first polarizing film, an optical compensation film having a first retardation region in contact with the first polarizing film and a second retardation region in contact with the first retardation region, a first substrate, a liquid crystal layer, a second substrate, and a second polarizing film, all disposed in this order, and shows parallel alignment of the liquid crystal molecules in the nematic liquid crystal material with respect to the surfaces of the pair of substrates on black display. The first retardation region produces ≤20 nm retardation in the plane and 20 to 120 nm in the thickness direction. The second retardation region is made of a discotic liquid crystal compound which is substantially vertically aligned. The slow phase axis of the second retardation region is parallel to the transmission axis of the first polarizing film and to the slow phase axis of the liquid crystal molecules on black display. <P>COPYRIGHT: (C)2005,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 is widely used in which a liquid crystal layer in which nematic liquid crystal is twisted is sandwiched between two orthogonal polarizing plates and an electric field is applied in a direction perpendicular to the substrate. 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). In addition, as 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), the optical compensation film has a positive birefringence and an optical axis. A method of combining a film in the plane of a film with a film having positive birefringence and an optical axis in the normal direction of the film (see Patent Document 5), 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 IPS mode liquid crystal cell that performs optical compensation with the stretched birefringent polymer film, it is necessary to use a plurality of films. As a result, the thickness of the optical compensation sheet increases, and the display device becomes thinner. It is disadvantageous. Moreover, since an adhesive layer is used for lamination | stacking of a stretched film, the adhesive layer contracted by the temperature / humidity change, and defects, such as peeling and curvature between films, may generate | occur | produce.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an IPS liquid crystal display device with a simple configuration and not only display quality but also a viewing angle that is remarkably improved.

The object of the present invention has been achieved by the following liquid crystal display devices (1) to (10).
(1) a first polarizing film, an optical compensation film comprising a first retardation region in contact with the first polarizing film and a second retardation region in contact with the first retardation region, a first substrate, and a nematic liquid crystal material A liquid crystal display device in which a liquid crystal layer, a second substrate, and a second polarizing film are arranged in this order, and liquid crystal molecules of the nematic liquid crystal material are aligned parallel to the surfaces of the pair of substrates at the time of black display Because
Using 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, Re = (nx−ny) × d
The in-plane retardation Re of the first retardation region defined by is 20 nm or less, and Rth = ((nx + ny) / 2−nz) × d
The retardation Rth in the thickness direction of the first retardation region defined by is composed of a composition containing a discotic liquid crystal compound in which the second retardation region is substantially vertically aligned, 2. A liquid crystal display device, wherein the slow axis of the two retardation region is parallel to the transmission axis of the first polarizing film and the slow axis direction of the liquid crystal molecules during black display.
(2) The liquid crystal display device according to (1), wherein Re of the second retardation region of the optical compensation film is 50 nm to 200 nm.
(3) The first retardation region is composed of a plurality of layers, a layer in contact with the second retardation region among the plurality of layers is an alignment film, and the second retardation region is at least a discotic liquid crystal. The liquid crystal display device according to (1) or (2), comprising an air interface alignment agent that reduces the tilt angle of the director of the discotic liquid crystal compound on the air interface side with the functional compound.
(4) The liquid crystal display device according to any one of (1) to (3), further including a second polarizing film on the outer side of the second substrate.
The “outside of the second substrate” refers to a side where the liquid crystal layer is not located when the second substrate is taken as the center.
(5) It has a pair of protective films arranged with the second polarizing film in between, and the thickness direction retardation Rth of the protective film closer to the liquid crystal layer in the pair of protective films is 40 nm or less ( 4) Liquid crystal display device.
(6) It has a pair of protective films arranged with the second polarizing film in between, and the thickness direction retardation Rth of the protective film closer to the liquid crystal layer of the pair of protective films is 20 nm or less ( 4) or the liquid crystal display device of (5).

(7) It has a pair of protective film arrange | positioned on both sides of the said 2nd polarizing film, The thickness of the protective film near the liquid crystal layer among this pair of protective films is 10-60 micrometers (4)-( The liquid crystal display device according to any one of 6).
(8) The protective film on the side close to the liquid crystal layer among the pair of protective films arranged with the second polarizing film interposed therebetween is any one of (4) to (7), which is a cellulose acetate film or a norbornene film Liquid crystal display device.
(9) Of the pair of protective films arranged with the second polarizing film interposed therebetween, the protective film on the side close to the liquid crystal layer has a layer containing a rod-like liquid crystalline compound that is vertically aligned with the cellulose acetate film (4) Liquid crystal display device in any one of-(8).
(10) The first retardation region is composed of a plurality of layers, and a layer in contact with the first polarizing film among the plurality of layers functions as a protective film for the first polarizing film (1) to (9). Any one of the liquid crystal display devices.

  In-plane retardation Re defined by Re = (nx−ny) × d using the refractive index nx and ny (nx ≧ ny) in the layer plane, the refractive index nz in the thickness direction, and the thickness d of the film. Is 20 nm or less, and the thickness direction retardation Rth defined by Rth = ((nx + ny) / 2−nz) × d is substantially perpendicular to the first retardation region having a thickness Rth of 20 nm to 120 nm. A second retardation region composed of a 200 nm discotic liquid crystal compound has a slow axis of the second retardation region parallel to the transmission axis of the first polarizing film and the slow axis direction of liquid crystal molecules during black display. And when the second retardation region is arranged so as to be closer to the liquid crystal layer side than the first retardation region, when viewed from an oblique azimuth angle direction without changing any characteristics in the front direction. The absorption axis of the two polarizing plates is 9 It is possible to improve the decrease in contrast caused by the deviation from 0 degrees, particularly the decrease in contrast from an oblique direction of 45 degrees. Furthermore, further improvement in contrast can be realized by setting the Rth of the protective film of the second polarizing film to 40 nm or less or the thickness to 60 μm or less.

BEST MODE FOR CARRYING OUT THE INVENTION

  In the following, one embodiment of the liquid crystal display device of the present invention and its constituent members will be sequentially described. 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.

  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 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 a first polarizing film 8, an optical compensation film 10, a first substrate 14, a liquid crystal layer 16, a second substrate 18, and a second polarizing film 21. The first polarizing film 8 and the second polarizing film 21 are sandwiched between protective films 7a and 7b and 20a and 20b, respectively. The optical compensation film 10 includes a first retardation region 11 including a protective film 7 b in contact with the first polarizing film 8 and a second retardation region 12 in contact with the first phase region 11.

  In the liquid crystal display device of FIG. 2, the liquid crystal cell includes a first substrate 14 and a second substrate 17, and a liquid crystal layer 16 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) is formed on the surfaces of the substrates 14 and 18 that are in contact with the liquid crystal layer 16 so that the liquid crystal molecules are aligned substantially parallel to the surface of the substrate and are rubbed on the alignment film. By the processing directions 15 and 19 and the like, the alignment direction of liquid crystal molecules in a state in which no voltage is applied or in a low application state is controlled. 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 14 or 17.

  FIG. 1 schematically shows the alignment of liquid crystal molecules in one pixel region of the liquid crystal layer 16. FIG. 1 shows the alignment of liquid crystal molecules in a very small area corresponding to one pixel of the liquid crystal layer 16 in the rubbing direction 4 of the alignment film formed on the inner surfaces of the substrates 14 and 18 and the substrates 14 and 18. 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. A display 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.

  In FIG. 2 again, the transmission axis 9 of the first polarizing film 8 and the transmission axis 22 of the second polarizing film 21 are arranged orthogonally. The optical compensation film 10 is composed of two regions, a first retardation region 11 and a second retardation region 12. The slow axis 13 of the second retardation region 12 is parallel to the transmission axis 9 of the first polarizing film 8 and the slow axis direction 17 of the liquid crystal molecules in the liquid crystal layer 16 during black display, and the second The retardation region 12 is disposed closer to the liquid crystal layer 16 than the first retardation region 11. The optical characteristics of the two regions constituting the optical compensation film will be described later.

    In the liquid crystal display device shown in FIG. 2, the configuration in which the first polarizing film 8 is sandwiched between the two protective films 7a and 7b is shown, but the protective film 7b may be omitted. In the case where the protective film 7b is disposed, the protective film 7b is one of the layers constituting the first retardation region 11 in the present invention. In the liquid crystal display device shown in FIG. 2, the second polarizing film 21 is also sandwiched between two protective films 20a and 20b. The thickness direction retardation Rth of the protective film 20a on the side close to the liquid crystal layer 16 is preferably 40 nm or less (more preferably 20 μm or less), or the thickness is preferably 60 μm or less.

  In addition, in FIG. 2, although the aspect of the display device of the transmission mode provided with the upper side polarizing plate and the lower side polarizing plate was shown, this invention may be the aspect of the reflection mode provided with only one polarizing plate, In such a case, since the optical path in the liquid crystal cell is doubled, the optimum value of Δn · d is about the above half value.

  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 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. In addition, 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 reflected on the back surface of the liquid crystal cell or the inner surface of the lower substrate of the liquid crystal cell. Place the membrane. 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.

[First retardation region of optical compensation film]
The optical characteristics of the first retardation region are represented by Re = (nx−ny) × d using 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. The in-plane retardation Re defined by is 20 nm or less, more preferably 10 nm or less, and most preferably 5 nm or less. The thickness direction retardation Rth defined by Rth = ((nx + ny) / 2−nz) × d is 20 nm to 120 nm, and more preferably 40 nm to 100 nm. When the protective film 7b that protects the first polarizing film 8 has optical anisotropy, the protective film 7b is a layer constituting the first retardation region 11, so that Rth of the protective film and others It is required that the total Rth of the layers is 40 nm to 100 nm.

  The retardation film having this optical characteristic includes a retardation film made of a birefringent polymer film, and an optically anisotropic layer formed by coating or transferring a low molecular weight or high molecular liquid crystalline compound on a transparent support. In the present invention, any of them can be used.

  A retardation film made of a birefringent polymer film having the above optical characteristics can be easily formed by biaxially stretching a polymer film. In addition, cellulose acylates that exhibit this optical property by simply casting without stretching can be suitably used. As such cellulose acylate, those described in JP-A-2002-90541 can be used. As a material for the polymer film, a synthetic polymer (eg, polycarbonate, polysulfone, polyethersulfone, polyacrylate, polymethacrylate, norbornene resin, cellulose acetate) is generally used.

  As a retardation film formed on a transparent support by coating or transfer, a rod-like cholesteric liquid crystalline composition containing a chiral structural unit is aligned after its helical axis is oriented substantially perpendicular to the substrate, Examples thereof include those obtained by horizontally aligning a discotic liquid crystalline compound having a negative intrinsic birefringence (director is perpendicular to the substrate) and those obtained by casting and fixing a polyimide polymer on the substrate.

[Second retardation region of optical compensation film]
The second retardation region includes a substantially vertically aligned discotic liquid crystal compound, and its slow axis is arranged in parallel to the transmission axis of the first polarizing film and the slow axis direction of the liquid crystal molecules during black display. The The Re of the second retardation region is preferably 50 nm to 200 nm, and more preferably 80 nm to 160 nm. This adjustment of Re is performed by controlling the thickness of the discotic liquid crystal layer to be formed by coating. Further, the discotic liquid crystalline compound needs to be aligned substantially perpendicular to the film surface (average inclination angle in the range of 70 to 90 degrees). When the average inclination angle is smaller than this, the light leakage distribution becomes asymmetric.

  Discotic liquid crystalline compounds are disclosed in various documents (C. Destrade et al., Mol. Crysr. Liq. Cryst., Vol. 71, page 111 (1981); edited by The Chemical Society of Japan, Quarterly Chemical Review, No. 22, Liquid Crystal Chemistry, Chapter 5, Chapter 10 Section 2 (1994); B. Kohne et al., Angew. Chem. Soc. Chem. Comm., Page 1794 (1985); J. Zhang et al., J Am.Chem.Soc., Vol.116, page 2655 (1994)). The polymerization of the discotic liquid crystalline compound is described in JP-A-8-27284.

The discotic liquid crystalline compound preferably has a polymerizable group so that it can be fixed by polymerization. For example, a structure in which a polymerizable group is bonded as a substituent to a discotic core of a discotic liquid crystalline compound can be considered. However, when a polymerizable group is directly connected to the discotic core, the alignment state is maintained in the polymerization reaction. It becomes difficult. Therefore, a structure having a linking group between the discotic core and the polymerizable group is preferable. That is, the discotic liquid crystalline compound having a polymerizable group is preferably a compound represented by the following formula.
D (-LP) _n
In the formula, D is a discotic core, L is a divalent linking group, P is a polymerizable group, and n is an integer of 4 to 12. Preferred specific examples of the discotic core (D), the divalent linking group (L) and the polymerizable group (P) in the above formula are (D1) to (D15) described in JP-A No. 2001-4837, respectively. ), (L1) to (L25), and (P1) to (P18), and the contents described in the publication can be preferably used.

  The second retardation region may be composed of only a layer formed from a composition containing a discotic liquid crystal, or may be composed of a layer formed from a composition containing a discotic liquid crystal and other layers. There may be. In the latter case, a laminate with a stretched polystyrene film or a laminate with an optically isotropic film such as a cycloolefin can be suitably used.

[Bar-shaped liquid crystalline compound]
The liquid crystal display device of the present invention may have a retardation layer formed from a composition containing a rod-like liquid crystalline compound. As will be described later, the protective film of the second polarizing film is preferably composed of a retardation film formed from a polymer film, preferably a polymer film of cellulose acylate and a composition containing a rod-like liquid crystalline compound. Examples of the rod-like liquid crystalline compound 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 low-molecular liquid crystalline molecules as described above but also high-molecular liquid crystalline molecules can be used.

  The liquid crystal compound used in the present invention, for example, a rod-like liquid crystal compound, is preferably substantially vertically aligned. In the case of a rod-like liquid crystalline compound, “substantially perpendicular” means that the angle formed by the film surface and the director of the rod-like liquid crystalline compound is in the range of 70 ° to 90 °. In the case of a discotic liquid crystalline compound, it means that the average angle (average inclination angle) between the disk surface and the surface of the optically anisotropic layer 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 orientation or hybrid orientation, the average inclination angle is preferably 70 ° to 90 °, more preferably 75 ° to 90 °, and most preferably 80 ° to 90 °.

[Method of forming retardation layer containing liquid crystalline compound]
The retardation layer containing a liquid crystal compound is formed on a support by applying a coating liquid containing a rod-like liquid crystal compound or a discotic liquid crystal compound, or the following polymerizable initiator, air interface alignment agent or other additive. It is formed by coating on the vertical 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 vertically aligned liquid crystal compound is preferably fixed while maintaining the alignment state. The immobilization is preferably performed by a polymerization reaction of the polymerizable group (P) introduced into the liquid crystal compound. The polymerization reaction includes a thermal polymerization reaction using a thermal polymerization initiator and a photopolymerization reaction using a photopolymerization initiator. 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) Description), 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. Light irradiation for polymerization of discotic liquid crystalline molecules is preferably performed using ultraviolet rays. The irradiation energy is preferably ^{20mJ / cm 2 ~50J / 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. The thickness of the retardation layer is preferably 0.1 to 10 μm, more preferably 0.5 to 5 μm, and most preferably 1 to 5 μm.

[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. As the acid to be mixed, carboxylic acid, sulfonic acid and amino acid are preferably used. You may use what shows the acidity among the below-mentioned air interface aligning agent. 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 discotic 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 an arbitrary 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 can be obtained by rubbing the surface after crosslinking the polymer layer as described above.

  For the rubbing treatment, a treatment method widely adopted as a liquid crystal alignment treatment process of LCD can be applied. That is, a method of obtaining the orientation by rubbing the surface of the orientation film in a certain direction using paper, gauze, felt, rubber, nylon, polyester fiber or the like can be used. In general, it is carried out by rubbing several times using a cloth in which fibers having a uniform length and thickness are flocked on average.

  In order to uniformly align the discotic liquid crystalline compound, it is preferable to control the alignment direction with a rubbing-treated vertical alignment film, while it is preferable not to perform the rubbing treatment 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 a retardation layer, and only the retardation layer is formed on the polymer film (or transparent support). You may transcribe.

[Air interface 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. The action of vertically aligning the liquid crystal compound corresponds to the action of reducing the tilt angle of the director, that is, the angle formed between the director and the coated liquid crystal air side surface in the discotic liquid crystal compound. As the compound that decreases the tilt angle of the director of the discotic liquid crystal molecule, a polymer containing a rigid structural unit having an excluded volume effect such as a maleimide group represented by the following general formula (1) is preferably used. It is done. Moreover, by mix | blending these compounds, applicability | paintability is improved and generation | occurrence | production of a nonuniformity or a repellency is suppressed.

  In the formula (1), A represents a repeating unit represented by the following general formula (2), B represents a repeating unit derived from an ethylenically unsaturated monomer, a and b are mass percentages representing a copolymerization ratio, a represents a numerical value of 1 to 100% by mass, and b represents a numerical value of 0 to 99% by mass.

In formula (2), X, X ¹ and X ² each independently represent a hydrogen atom or a substituent.
More specifically, in the above general formula (2), examples of the substituent represented by X, X ¹ and X ² include the following groups.
An alkyl group (preferably an alkyl group having 1 to 20 carbon atoms, more preferably 1 to 12 carbon atoms, particularly preferably 1 to 8 carbon atoms, such as a methyl group, an ethyl group, an isopropyl group, a tert-butyl group, n-octyl group, n-decyl group, n-hexadecyl group, cyclopropyl group, cyclopentyl group, cyclohexyl group and the like, alkenyl group (preferably having 2 to 20 carbon atoms, more preferably 2 to 12 carbon atoms, Particularly preferred are alkenyl groups having 2 to 8 carbon atoms, such as vinyl group, aryl group, 2-butenyl group and 3-pentenyl group), alkynyl groups (preferably having 2 to 20 carbon atoms, more preferred). Is an alkynyl group having 2 to 12 carbon atoms, particularly preferably 2 to 8 carbon atoms, such as propargyl group and 3-pentynyl group. An aryl group (preferably an aryl group having 6 to 30 carbon atoms, more preferably 6 to 20 carbon atoms, particularly preferably 6 to 12 carbon atoms, such as a phenyl group, a 2,6-diethylphenyl group, 3,5-ditrifluoromethylphenyl group, naphthyl group, biphenyl group and the like), substituted or unsubstituted amino group (preferably having 0 to 20 carbon atoms, more preferably 0 to 10 carbon atoms, particularly preferably carbon An amino group of 0 to 6, and examples thereof include an unsubstituted amino group, a methylamino group, a dimethylamino group, a diethylamino group, and an anilino group).

An alkoxy group (preferably having 1 to 20 carbon atoms, more preferably 1 to 10 carbon atoms, particularly preferably 1 to 6 carbon atoms, and examples thereof include a methoxy group, an ethoxy group, and a butoxy group), an alkoxycarbonyl group (Preferably 2 to 20 carbon atoms, more preferably 2 to 10 carbon atoms, particularly preferably 2 to 6 carbon atoms such as methoxycarbonyl group and ethoxycarbonyl group), acyloxy group (preferably 2 carbon atoms) -20, more preferably 2 to 10 carbon atoms, particularly preferably 2 to 6 carbon atoms such as an acetoxy group and a benzoyloxy group), an acylamino group (preferably 2 to 20 carbon atoms, more preferably carbon atoms). 2 to 10, particularly preferably 2 to 6 carbon atoms, such as acetylamino group and benzoylamino group. ), An alkoxycarbonylamino group (preferably having 2 to 20 carbon atoms, more preferably 2 to 10 carbon atoms, particularly preferably 2 to 6 carbon atoms, such as a methoxycarbonylamino group), aryloxycarbonyl An amino group (preferably having 7 to 20 carbon atoms, more preferably 7 to 16 carbon atoms, particularly preferably 7 to 12 carbon atoms, such as a phenyloxycarbonylamino group), a sulfonylamino group (preferably C1-C20, More preferably, it is C1-C10, Most preferably, it is C1-C6, for example, a methanesulfonylamino group, a benzenesulfonylamino group, etc.), a sulfamoyl group (preferably carbon number) 0 to 20, more preferably 0 to 10 carbon atoms, particularly preferably 0 to 6 carbon atoms, Sulfamoyl group, methylsulfamoyl group, dimethylsulfamoyl group, phenylsulfamoyl group, etc.), carbamoyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 10 carbon atoms, particularly preferably Has 1 to 6 carbon atoms, and examples thereof include an unsubstituted carbamoyl group, a methylcarbamoyl group, a diethylcarbamoyl group, and a phenylcarbamoyl group).

An alkylthio group (preferably having 1 to 20 carbon atoms, more preferably 1 to 10 carbon atoms, particularly preferably 1 to 6 carbon atoms, such as a methylthio group and an ethylthio group), an arylthio group (preferably a carbon atom) 6 to 20, more preferably 6 to 16 carbon atoms, particularly preferably 6 to 12 carbon atoms, such as a phenylthio group, and a sulfonyl group (preferably 1 to 20 carbon atoms, more preferably carbon 1 to 10, particularly preferably 1 to 6 carbon atoms, for example, mesyl group, tosyl group and the like, sulfinyl group (preferably 1 to 20 carbon atoms, more preferably 1 to 10 carbon atoms, especially Preferably it is C1-C6, for example, a methanesulfinyl group, a benzenesulfinyl group etc. are mentioned), a ureido group (preferably carbon number) To 20, more preferably 1 to 10 carbon atoms, particularly preferably 1 to 6 carbon atoms, and examples thereof include an unsubstituted ureido group, a methylureido group, and a phenylureido group), a phosphoric acid amide group (preferably Has 1 to 20 carbon atoms, more preferably 1 to 10 carbon atoms, particularly preferably 1 to 6 carbon atoms, and examples thereof include a diethylphosphoric acid amide group and a phenylphosphoric acid amide group), a hydroxy group, a mercapto group Group, halogen atom (eg fluorine atom, chlorine atom, bromine atom, iodine atom), cyano group, sulfo group, carboxyl group, nitro group, hydroxamic acid group, sulfino group, hydrazino group, imino group, heterocyclic group (preferably A heterocyclic group having 1 to 30 carbon atoms, more preferably 1 to 12 carbon atoms, for example, a hetero atom such as a nitrogen atom, an oxygen atom, or a sulfur atom. For example, an imidazolyl group, a pyridyl group, a quinolyl group, a furyl group, a piperidyl group, a morpholino group, a benzoxazolyl group, a benzimidazolyl group, a benzthiazolyl group), a silyl group (preferably , A silyl group having 3 to 40 carbon atoms, more preferably 3 to 30 carbon atoms, and particularly preferably 3 to 24 carbon atoms, and examples thereof include a trimethylsilyl group and a triphenylsilyl group.
These substituents may be further substituted with these substituents. Further, when two or more substituents are present, they may be the same or different. If possible, they may be bonded to each other to form a ring.

X is preferably a hydrogen atom, a substituted or unsubstituted alkyl group (including a cycloalkyl group) or an aryl group, and particularly preferably a substituted or unsubstituted alkyl group (including a cycloalkyl group) or an aryl group. And most preferably an aryl group. X ¹ and X ² are each independently preferably a hydrogen atom, a halogen atom or a substituted or unsubstituted alkyl group, particularly preferably a hydrogen atom or a substituted or unsubstituted alkyl group, most preferably a hydrogen atom. is there.

  In the general formula (1), B is a repeating unit (hereinafter also referred to as “repeat unit B”) derived from at least one ethylenically unsaturated monomer (hereinafter also referred to as “monomer B”), and is exemplified below. It is preferably a repeating unit derived from one type selected from the monomer group or a repeating unit derived from a copolymer obtained by combining two or more types independently and freely selected from the following monomer group. There is no restriction | limiting in particular in the monomer which can be used, If a normal radical polymerization reaction is possible, it can use suitably.

Monomer group (1) Alkenes ethylene, propylene, 1-butene, isobutene, 1-hexene, 1-dodecene, 1-octadecene, 1-eicosene, hexafluoropropene, vinylidene fluoride, chlorotrifluoroethylene, 3, 3, 3-trifluoropropylene, tetrafluoroethylene, vinyl chloride, vinylidene chloride, etc .;
(2) Dienes 1,3-butadiene, isoprene, 1,3-pentadiene, 2-ethyl-1,3-butadiene, 2-n-propyl-1,3-butadiene, 2,3-dimethyl-1,3 -Butadiene, 2-methyl-1,3-pentadiene, 1-phenyl-1,3-butadiene, 1-α-naphthyl-1,3-butadiene, 1-β-naphthyl-1,3-butadiene, 2-chloro -1,3-butadiene, 1-bromo-1,3-butadiene, 1-chlorobutadiene, 2-fluoro-1,3-butadiene, 2,3-dichloro-1,3-butadiene, 1,1,2- Trichloro-1,3-butadiene and 2-cyano-1,3-butadiene, 1,4-divinylcyclohexane and the like;

(3) Derivatives of α, β-unsaturated carboxylic acid (3a) Alkyl acrylates Methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, tert-butyl acrylate , Amyl acrylate, n-hexyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, tert-octyl acrylate, dodecyl acrylate, phenyl acrylate, benzyl acrylate, 2-chloroethyl acrylate, 2-bromoethyl acrylate, 4-chlorobutyl acrylate, 2-cyanoethyl acrylate, 2-acetoxyethyl acrylate, methoxybenzyl Chryrate, 2-chlorocyclohexyl acrylate, furfuryl acrylate, tetrahydrofurfuryl acrylate, 2-methoxyethyl acrylate, ω-methoxypolyethylene glycol acrylate (number of added polyoxyethylene: n = 2 to 100), 3-methoxy Butyl acrylate, 2-ethoxyethyl acrylate, 2-butoxyethyl acrylate, 2- (2-butoxyethoxy) ethyl acrylate, 1-bromo-2-methoxyethyl acrylate, 1,1-dichloro-2-ethoxyethyl acrylate, glycidyl acrylate Such);

(3b) Alkyl methacrylates Methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, sec-butyl methacrylate, tert-butyl methacrylate, amyl methacrylate, n-hexyl methacrylate, cyclohexyl methacrylate, 2 -Ethylhexyl methacrylate, n-octyl methacrylate, stearyl methacrylate, benzyl methacrylate, phenyl methacrylate, allyl methacrylate, furfuryl methacrylate, tetrahydrofurfuryl methacrylate, cresyl methacrylate, naphthyl methacrylate, 2-methoxyethyl methacrylate, 3-methoxybutyl methacrylate, ω Methoxypolyethylene glycol methacrylate (number of added polyoxyethylene: n = 2 to 100), 2-acetoxyethyl methacrylate, 2-ethoxyethyl methacrylate, 2-butoxyethyl methacrylate, 2- (2-butoxyethoxy) ethyl methacrylate Glycidyl methacrylate, 3-trimethoxysilylpropyl methacrylate, allyl methacrylate, 2-isocyanatoethyl methacrylate, etc .;

(3c) Diesters of unsaturated polycarboxylic acids Dimethyl maleate, dibutyl maleate, dimethyl itaconate, dibutyl taconate, dibutyl crotonate, dihexyl crotonate, diethyl fumarate, dimethyl fumarate, etc .;

(3d) Amides of α, β-unsaturated carboxylic acids N, N-dimethylacrylamide, N, N-diethylacrylamide, Nn-propylacrylamide, N-tertbutylacrylamide, N-tertoctylmethacrylamide, N- Cyclohexylacrylamide, N-phenylacrylamide, N- (2-acetoacetoxyethyl) acrylamide, N-benzylacrylamide, N-acryloylmorpholine, diacetone acrylamide, N-methylmaleimide and the like;

(4) Unsaturated nitriles Acrylonitrile, methacrylonitrile, etc .;
(5) Styrene and its derivatives Styrene, vinyl toluene, ethyl styrene, p-tert butyl styrene, methyl p-vinyl benzoate, α-methyl styrene, p-chloromethyl styrene, vinyl naphthalene, p-methoxy styrene, p-hydroxy Methyl styrene, p-acetoxy styrene, etc .;
(6) Vinyl esters Vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl benzoate, vinyl salicylate, vinyl chloroacetate, vinyl methoxyacetate, vinyl vinyl acetate, etc .;

(7) Vinyl ethers Methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, tert-butyl vinyl ether, n-pentyl vinyl ether, n-hexyl vinyl ether, n-octyl vinyl ether, n-dodecyl Vinyl ether, n-eicosyl vinyl ether, 2-ethylhexyl vinyl ether, cyclohexyl vinyl ether, fluorobutyl vinyl ether, fluorobutoxyethyl vinyl ether, etc .;
(8) Other polymerizable monomers N-vinyl pyrrolidone, methyl vinyl ketone, phenyl vinyl ketone, methoxyethyl vinyl ketone, 2-vinyl oxazoline, 2-isopropenyl oxazoline and the like.

  In the general formula (1), B preferably contains at least one repeating unit represented by the following general formula (3).

In formula (3), R ¹ , R ² and R ³ each independently represent a hydrogen atom, an alkyl group, a halogen atom or a group represented by -LQ. L represents a divalent linking group, and Q represents an alkyl group or a polar group having hydrogen bonding properties.

In formula (3), R ¹ , R ² and R ³ are each independently a hydrogen atom, an alkyl group, a halogen atom (for example, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc.) or -LQ described later. Are preferably a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a chlorine atom, or a group represented by -LQ, more preferably a hydrogen atom or an alkyl having 1 to 4 carbon atoms. And particularly preferred are a hydrogen atom and an alkyl group having 1 to 2 carbon atoms. Specific examples of the alkyl group include methyl group, ethyl group, n-propyl group, n-butyl group, sec-butyl group and the like. The alkyl group may have a suitable substituent. Examples of the substituent include a halogen atom, aryl group, heterocyclic group, alkoxyl group, aryloxy group, alkylthio group, arylthio group, acyl group, hydroxyl group, acyloxy group, amino group, alkoxycarbonyl group, acylamino group, oxycarbonyl Group, carbamoyl group, sulfonyl group, sulfamoyl group, sulfonamido group, sulfolyl group, carboxyl group and the like.
The carbon number of the alkyl group does not include the carbon atom of the substituent. The same applies to the carbon number of other groups.

L is preferably a group selected from the following linking group group or a divalent linking group formed by combining two or more thereof.
(Linked group group)
Single bond, —O—, —CO—, —NR ⁴ — (R ⁴ represents a hydrogen atom, an alkyl group, an aryl group or an aralkyl group), —S—, —SO ₂ —, —P (═O) ( OR ⁵ ) — (R ⁵ represents an alkyl group, an aryl group, or an aralkyl group), an alkylene group, and an arylene group.
L preferably contains a single bond, —O—, —CO—, —NR ⁴ —, —S—, —SO ₂ —, an alkylene group or an arylene group, and —CO—, —O—, —NR ⁴ -, more preferably contains an alkylene group or an arylene group, -CO -, - O -, - NR ⁴ - or even more preferably contains an alkylene group.

When L contains an alkylene group, the alkylene group preferably has 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and particularly preferably 1 to 6 carbon atoms. Specific examples of particularly preferred alkylene groups include methylene, ethylene, trimethylene, tetrabutylene, hexamethylene groups and the like.
When L contains an arylene group, the carbon number of the arylene group is preferably 6 to 24, more preferably 6 to 18, and particularly preferably 6 to 12. Specific examples of particularly preferred arylene groups include phenylene and naphthalene groups.
When L contains a divalent linking group (that is, an aralkylene group) obtained by combining an alkylene group and an arylene group, the carbon number of the aralkylene group is preferably 7 to 34, more preferably 7 to 26, and particularly preferably. 7-16. Specific examples of particularly preferred aralkylene groups include a phenylenemethylene group, a phenyleneethylene group, and a methylenephenylene group.

The group listed as L may have a suitable substituent. Examples of such a substituent include those similar to the substituents exemplified above as the substituents for R ^{1 to} R ³ .
Although the specific structure of L is illustrated below, this invention is not limited to these specific examples.

The polar group having hydrogen bonding property represented by Q is preferably a hydroxyl group, a carboxyl group, or a salt of a carboxyl group (for example, lithium salt, sodium salt, potassium salt, ammonium salt (for example, ammonium, tetramethylammonium, trimethyl-2- hydroxyethyl ammonium, tetrabutylammonium, trimethylbenzylammonium, and dimethylphenyl ammonium), such as pyridinium salts), amides of carboxylic acid (N unsubstituted, or N- mono-lower alkyl substituted compound, e.g. -CONH _2, etc. -CONHCH ₃ ) A sulfo group, a salt of a sulfo group (examples of cations forming a salt are the same as those described in the above carboxyl group), a sulfonamide group (N unsubstituted or N-mono lower alkyl substituted, -SO ₂ NH ₂ , such as -SO ₂ NHCH _3), phospho group, Salts of phospho groups (examples of cations that form salts are the same as those described above for carboxyl groups), phosphonamides (N unsubstituted or N-mono lower alkyl substituted, such as -OP (= O) (NH ₂ ) ₂ , —OP (═O) (NHCH ₃ ) ₂ ), ureido group (—NHCONH ₂ ), amino group unsubstituted or monosubstituted at the N position (—NH ₂ , —NHCH ₃ ) and the like ( Here, the lower alkyl group represents a methyl group or an ethyl group). A hydroxyl group, a carboxyl group, a sulfo group or a phospho group is more preferred, and a hydroxyl group or a carboxyl group is particularly preferred.

  The alkyl group represented by Q is preferably an alkyl group having 1 to 20 carbon atoms, more preferably 1 to 12 carbon atoms, and particularly preferably 1 to 8 carbon atoms, such as a methyl group, an ethyl group, and an isopropyl group. Butyl group, tert-butyl group, n-octyl group, n-decyl group, n-hexadecyl group, cyclopropyl group, cyclopentyl group, cyclohexyl group and the like.

  The repeating units A and B contained in the polymer represented by the general formula (1) may be one kind alone, or two or more kinds of repeating units A and B may be present simultaneously. B is preferably composed of two or more types of repeating units in which a hydroxyl group and a carboxyl group are present simultaneously, and is composed of three or more types of repeating units in which a hydroxyl group, a carboxyl group and an alkyl group are simultaneously present. Most preferably.

  Although a is a numerical value of 1-100 mass% and b is 0-99 mass%, Preferably a is 5-100 mass%, b is 0-95 mass%, More preferably, a is 10-100 mass%. % And b are 0 to 90% by mass, particularly preferably a is 30 to 100% by mass and b is 0 to 70% by mass or more. Since the above-mentioned mass percentage easily varies in a preferable range depending on the molecular weight of the monomer used, the content of the repeating unit can be accurately defined by expressing it in terms of moles of functional groups per unit mass of the polymer. When this notation is used, the polymer of the present invention preferably contains 0.1 mmol / g to 10 mmol / g of hydrogen-bonding polar groups, and has a hydrogen bondability of 0.2 mmol / g to 8 mmol / g. It is particularly preferable to contain a polar group.

  The polymerization method for producing the polymer represented by the general formula (1) is not particularly limited. For example, polymerization methods such as cationic polymerization, radical polymerization, or anionic polymerization using a vinyl group. Among these, radical polymerization is particularly preferred because it can be used for general purposes.

  As the polymerization initiator for radical polymerization, known compounds such as radical thermal polymerization initiators and radical photopolymerization initiators can be used, and it is particularly preferable to use radical thermal polymerization initiators. Here, the radical thermal polymerization initiator is a compound that generates radicals by heating to a decomposition temperature or higher. Examples of such radical thermal polymerization initiators include diacyl peroxide (acetyl peroxide, benzoyl peroxide, etc.), ketone peroxide (methyl ethyl ketone peroxide, cyclohexanone peroxide, etc.), hydroperoxide (hydrogen peroxide, tert. -Butyl hydroxide, cumene hydroperoxide, etc.), dialkyl peroxide (di-tert-butyl peroxide, dicumyl peroxide, dilauroyl peroxide, etc.), peroxyesters (tert-butyl peroxyacetate, tert) -Butyl peroxypivalate, etc.), azo compounds (azobisisobutyronitrile, azobisisovaleronitrile, etc.), persulfates (ammonium persulfate, sodium persulfate) And potassium persulfate) and the like. Such radical thermal polymerization initiators can be used singly or in combination of two or more.

  The radical polymerization method is not particularly limited, and an emulsion polymerization method, a suspension polymerization method, a bulk polymerization method, a solution polymerization method, and the like can be used. The solution polymerization, which is a typical radical polymerization method, will be described more specifically. The outlines of other polymerization methods are the same, and details thereof are described, for example, in “Polymer Science Experimental Method” edited by Polymer Society (Tokyo Kagaku Dojin, 1981).

  An organic solvent is used for solution polymerization. These organic solvents can be arbitrarily selected as long as the objects and effects of the present invention are not impaired. These organic solvents are usually organic compounds having boiling points under atmospheric pressure in the range of 50 to 200 ° C., and organic compounds that uniformly dissolve each component are preferred. Examples of preferable organic solvents include alcohols such as isopropanol and butanol, ethers such as dibutyl ether, ethylene glycol dimethyl ether, tetrahydrofuran and dioxane, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, ethyl acetate and acetic acid. Examples thereof include esters such as butyl, amyl acetate and γ-butyrolactone, and aromatic hydrocarbons such as benzene, toluene and xylene. In addition, these organic solvents can be used individually by 1 type or in combination of 2 or more types. Furthermore, a water-mixed organic solvent in which water is used in combination with the above organic solvent is also applicable from the viewpoint of the solubility of the monomer and the polymer to be produced.

  Also, the solution polymerization conditions are not particularly limited, but for example, it is preferable to heat within a temperature range of 50 to 200 ° C. for 10 minutes to 30 hours. Furthermore, in order not to deactivate the generated radicals, it is preferable to perform an inert gas purge not only during solution polymerization but also before the start of solution polymerization. Usually, nitrogen gas is suitably used as the inert gas.

In order to obtain the polymer of the present invention within a preferable molecular weight range, a radical polymerization method using a chain transfer agent is particularly effective.
As chain transfer agents, mercaptans (for example, octyl mercaptan, decyl mercaptan, dodecyl mercaptan, tert-dodecyl mercaptan, octadecyl mercaptan, thiophenol, p-nonylthiophenol, etc.), polyhalogenated alkyls (for example, carbon tetrachloride, chloroform, etc.) , 1,1,1-trichloroethane, 1,1,1-tribromooctane, etc.) and low-activity monomers (α-methylstyrene, α-methylstyrene dimer, etc.) can be used, preferably carbon These are mercaptans of formula 4 to 16. The amount of these chain transfer agents used is remarkably influenced by the activity of the chain transfer agent, the combination of the monomers, the polymerization conditions and the like, and must be precisely controlled. It is about 01 mol% to 50 mol%, preferably 0.05 mol% to 30 mol%, particularly preferably 0.08 mol% to 25 mol%. These chain transfer agents may be present in the system simultaneously with the target monomer whose degree of polymerization is to be controlled in the polymerization process, and the addition method is not particularly limited. It may be added after dissolved in the monomer, or may be added separately from the monomer.

  The polymer represented by the general formula (1) of the present invention preferably has a mass average molecular weight of 1,000,000 or less. More preferably, the weight average molecular weight is 500,000 or less, and particularly preferably the weight average molecular weight is 100,000 or less. The mass average molecular weight can be measured as a value in terms of polyethylene oxide (PEO) using gel permeation chromatography (GPC).

  Specific examples of the polymer represented by the general formula (1) that can be preferably used in the present invention are shown below, but the present invention is not limited to these specific examples. Here, the numerical values in the formula each represent a mass percentage indicating the composition ratio of each monomer, and Mw represents a mass average molecular weight in terms of PEO measured by GPC.

  In addition to the exemplified compounds, compounds described in JP-A Nos. 2002-20363 and 2002-129162 can be used as the air interface alignment agent. 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 can also be appropriately applied to the present invention.

  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.

[Other composition of retardation 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 discotic liquid crystalline molecules.

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

  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. The discotic nematic liquid crystal phase-solid phase transition temperature of the liquid crystal compound is preferably 70 to 300 ° C, more preferably 70 to 170 ° C.

[Support]
In the present invention, a transparent support may be used. As the transparent support, it is preferable to use a polymer film having a small wavelength dispersion. The transparent support preferably has a small optical anisotropy. That the support is transparent means that the light transmittance is 80% or more. Specifically, the small chromatic dispersion means that the ratio of Re400 / Re700 is preferably less than 1.2. Specifically, the small optical anisotropy means that in-plane retardation (Re) is preferably 20 nm or less, and more preferably 10 nm or less. Examples of the polymer include cellulose ester, polycarbonate, polysulfone, polyethersulfone, polyacrylate and polymethacrylate. Cellulose esters are preferred, acetyl cellulose is more preferred, and triacetyl cellulose 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 50 to 200 μm. In order to improve adhesion between the transparent support and the layer (adhesive layer, vertical alignment film or retardation layer) provided thereon, surface treatment (eg, glow discharge treatment, corona discharge treatment, ultraviolet light (UV) ) 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.

[Protective film for second polarizing plate]
The protective film for the second polarizing plate is preferably a protective film having no absorption in the visible light region, a light transmittance of 80% or more, and a small retardation based on birefringence. 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 retardation Rth in the thickness direction is preferably 0 to 40 nm, more preferably 0 to 20 nm, and most preferably 0 to 10 nm. Any film having this property can be preferably used, but from the viewpoint of durability of the polarizing film, a cellulose acetate or norbornene film is more preferable. Examples of the method for reducing Rth of the cellulose acetate film include methods described in JP-A Nos. 11-246704, 2001-247717, and Japanese Patent Application No. 2003-379975. Rth can also be reduced by reducing the thickness of the cellulose acetate film. The thickness of the cellulose acetate film as the protective film for the second polarizing plate is preferably 10 to 60 μm, and more preferably 20 to 45 μm.

  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 IPS mode liquid crystal cell 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 process 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 enclosed. The value of d · Δn of the liquid crystal layer was 300 nm.

<Preparation of optical compensation film 1>
(Production of first retardation region)
The following composition was put into a mixing tank and stirred while heating to dissolve each component to prepare a cellulose acetate solution having the following composition.
Composition of cellulose acetate solution Cellulose acetate with an acetylation degree of 60.9% 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 Mass part Methanol (second solvent) 54 parts by mass 1-butanol (third solvent) 11 parts by mass In another mixing tank, 16 parts by mass of the following retardation increasing agent, 80 parts by mass of methylene chloride, and 20 parts by mass of methanol were added. Then, the mixture was stirred while heating to prepare a retardation increasing agent solution. A dope was prepared by mixing 7 parts by mass of the retardation increasing agent solution with 487 parts by mass of the cellulose acetate solution and stirring sufficiently.

  The obtained dope was cast using a band casting machine. After the film surface temperature on the band reached 40 ° C., the film was dried with warm air of 60 ° C. for 1 minute, and the film was peeled off from the band. Next, the film was dried with a drying air at 140 ° C. for 10 minutes to produce a cellulose acetate film 1 having a thickness of 80 μm.

  The optical properties of this film were determined by measuring the light incident angle dependency of Re using an automatic birefringence meter (KOBRA-21ADH, manufactured by Oji Scientific Instruments). Re = 8 nm, Rth = 82 nm.

(Production of second retardation region)
After the surface of the cellulose acetate film 1 was saponified, an alignment film coating solution having the following composition was applied onto the film with a wire bar coater at 20 ml / m ² . The film was formed by drying with warm air of 60 ° C. for 60 seconds and further with warm air of 100 ° C. for 120 seconds. Next, the formed film was rubbed in a direction parallel to the slow axis direction of the film to form an alignment film.
Composition of Alignment Film Coating Solution Modified Polyvinyl Alcohol 10 parts by weight Water 371 parts by weight Methanol 119 parts by weight Glutaraldehyde 0.5 part by weight Paratoluenesulfonic acid 0.3 part by weight

  Next, 1.8 g of the following discotic liquid crystalline compound, 0.2 g of ethylene oxide-modified trimethylolpropane triacrylate (V # 360, manufactured by Osaka Organic Chemical Co., Ltd.), a photopolymerization initiator (IRGA) Cure 907, Ciba Geigy Co., Ltd.) 0.06 g, Sensitizer (Kaya Cure DETX, Nippon Kayaku Co., Ltd.) 0.02 g, Air Interface Side Vertical Alignment Agent (Exemplary Compound P-6) 0.01 g 3.9 g The solution dissolved in methyl ethyl ketone was applied with a wire bar # 3.4. This was attached to a metal frame and heated in a thermostatic bath at 125 ° C. for 3 minutes to align the discotic liquid crystal compound. Next, UV irradiation was performed for 30 seconds using a 120 W / cm high-pressure mercury lamp at 100 ° C. to crosslink the discotic liquid crystal compound. Then, it stood to cool to room temperature. Thus, the optical compensation film 1 was produced.

  Using an automatic birefringence meter (KOBRA-21ADH, manufactured by Oji Scientific Instruments Co., Ltd.), the light incident angle dependence of Re of the optical compensation film 1 is measured, and the pre-measured contribution of the cellulose acetate film is subtracted. As a result, the optical characteristics of only the discotic liquid crystal retardation layer were calculated. Re was 130 nm, Rth was −65 nm, the average tilt angle of the liquid crystal was 89.9 °, and the discotic liquid crystal was perpendicular to the film surface. It was confirmed that they were oriented. The slow axis direction was parallel to the rubbing direction of the alignment film.

  A polarizing film was produced by adsorbing iodine to a stretched polyvinyl alcohol film. Using the polyvinyl alcohol-based adhesive, the produced optical compensation film 1 was attached to one side of the polarizing film so that the cellulose acetate film was on the polarizing film side. The transmission axis of the polarizing film and the slow axis of the optical compensation film (the slow axis of the second retardation region also coincides with this) were arranged in parallel. A commercially available cellulose acetate film (Fujitac TD80UF, manufactured by Fuji Photo Film Co., Ltd., thickness 80 μm, Re = 3 nm, Rth = 45 nm) is subjected to saponification treatment, and a polyvinyl alcohol adhesive is used on the opposite side of the polarizing film. Pasted. This is arranged so that the slow axis of the optical compensation film 1 is parallel to the rubbing direction of the liquid crystal cell on one of the IPS mode liquid crystal cells 1 produced above (that is, the slow axis of the second retardation region is It was attached so that the slow axis of the liquid crystal molecules of the liquid crystal cell at the time of black display was parallel) and the discotic liquid crystal application surface side was the liquid crystal cell side. Subsequently, a commercially available polarizing plate (HLC2-5618, manufactured by Sanritz Co., Ltd.) was attached to the other side of the IPS mode liquid crystal cell 1 in a crossed Nicol arrangement to produce a liquid crystal display device.

<Measurement of leakage light of the manufactured liquid crystal display device>
The leakage light of the liquid crystal display device thus manufactured was measured. Leakage light when observed from the left diagonal direction of 70 ° was 0.12%.

[Example 2]
<Preparation of optical compensation film 2>
Using a commercially available cellulose acetate film (Fujitac TD80UF, manufactured by Fuji Photo Film Co., Ltd., thickness 80 μm, Re = 3 nm, Rth = 45 nm) as the first retardation region, the surface was saponified, and this film The same alignment film coating solution as in Example 1 was applied to the top with a wire bar coater at 20 ml / m ² . A film was formed by drying with warm air of 60 ° C. for 60 seconds and further with warm air of 100 ° C. for 120 seconds. Next, the formed film was rubbed in a direction parallel to the slow axis direction of the film to obtain an alignment film.

  Subsequently, on the alignment film, 1.8 g of the discotic liquid crystalline compound used in Example 1, 0.2 g of ethylene oxide-modified trimethylolpropane triacrylate (V # 360, manufactured by Osaka Organic Chemical Co., Ltd.), photopolymerization Initiator (Irgacure 907, manufactured by Ciba Geigy) 0.06 g, Sensitizer (Kayacure DETX, manufactured by Nippon Kayaku Co., Ltd.) 0.02 g, 3.9 g of 0.003 g of the following air interface side vertical alignment agent A solution dissolved in methyl ethyl ketone was applied with a # 3 wire bar. This was attached to a metal frame and heated in a thermostatic bath at 125 ° C. for 3 minutes to align the discotic liquid crystal compound. Next, UV irradiation was performed for 30 seconds using a 120 W / cm high-pressure mercury lamp at 100 ° C. to crosslink the discotic liquid crystal compound. Then, it stood to cool to room temperature. Thus, the optical compensation film 2 was produced.

  Using an automatic birefringence meter (KOBRA-21ADH, manufactured by Oji Scientific Instruments Co., Ltd.), the light incident angle dependency of Re of the optical compensation film 2 is measured, and the pre-measured contribution of the cellulose acetate film is subtracted. Thus, the optical characteristics of only the discotic liquid crystal retardation layer were calculated. Re was 115 nm, Rth was −57 nm, the average tilt angle of the liquid crystal was 89.9 °, and the discotic liquid crystal was perpendicular to the film surface. It was confirmed that they were oriented. The slow axis direction was parallel to the rubbing direction of the alignment film.

  One of the IPS mode liquid crystal cells 1 produced as described above is arranged so that the optical compensation sheet 2 produced as described above has a slow axis parallel to the rubbing direction of the liquid crystal cell (that is, the slow axis of the second retardation region). Is attached in such a way that the discotic liquid crystal application surface side is the liquid crystal cell side. Subsequently, a commercially available polarizing plate (HLC2-5618, manufactured by Sanritz Co., Ltd.) is pasted on the optical compensation sheet 2 so that the transmission axis is parallel to the rubbing direction of the liquid crystal cell. The same polarizing plate was attached to the other side in a crossed Nicol arrangement to produce a liquid crystal display device.

(Measurement of leakage light of the manufactured liquid crystal display device)
The leakage light of the liquid crystal display device thus manufactured was measured. The leakage light when observed from the left diagonal direction of 70 ° was 0.13%.

[Example 3]
<Production of Second Polarizing Plate 1>
Using a commercially available cellulose acetate film (Fujitac TD80UF, manufactured by Fuji Photo Film Co., Ltd., thickness 80 μm, Re = 3 nm, Rth = 45 nm), the surface was saponified, and a commercially available vertical alignment film was formed on the film. (JALS-204R, manufactured by Nippon Synthetic Rubber Co., Ltd.) was diluted 1: 1 with methyl ethyl ketone, and then 2.4 ml / m ^{2 was} applied with a wire bar coater. Immediately, it was dried with warm air of 120 ° C. for 120 seconds.

(Formation of vertically aligned rod-like liquid crystal compound layer)
On the alignment film, 1.8 g of the following rod-shaped liquid crystal compound, 0.06 g of photopolymerization initiator (Irgacure 907, manufactured by Ciba Geigy), 0.02 g of sensitizer (Kayacure DETX, manufactured by Nippon Kayaku Co., Ltd.), A solution obtained by dissolving 0.002 g of the following air interface side vertical alignment agent in 9.2 g of methyl ethyl ketone was applied with a # 2 wire bar. This was affixed to a metal frame and heated in a constant temperature bath at 100 ° C. for 2 minutes to align the rod-like liquid crystal compound. Next, using a 120 W / cm high-pressure mercury lamp at 100 ° C., UV irradiation was performed for 30 seconds to crosslink the rod-like liquid crystal compound. Then, it stood to cool to room temperature. Thus, the protective film 1 for the second polarizing plate was produced.

  Using an automatic birefringence meter (KOBRA-21ADH, manufactured by Oji Scientific Instruments Co., Ltd.), the light incident angle dependency of Re of the protective film 1 was measured. As a result, Re was 3 nm and Rth was 5 nm.

  Next, iodine is adsorbed to the stretched polyvinyl alcohol film to produce a polarizing film, and using the polyvinyl alcohol-based adhesive, the protective film 1 thus prepared is arranged on one side of the polarizing film so that the cellulose acetate film is on the polarizing film side. Pasted on. Subsequently, a commercially available cellulose acetate film (Fujitac TD80UF, manufactured by Fuji Photo Film Co., Ltd.) is subjected to saponification treatment, and a second polarizing plate is attached to the opposite side of the polarizing film using a polyvinyl alcohol adhesive. Formed. Further, in the same manner as in Example 1, the optical compensation film 1 was attached to one side of the polarizing film so that the cellulose acetate film was on the polarizing film side, and a commercially available cellulose acetate film was attached to the opposite side of the polarizing film. One polarizing plate is placed on one of the IPS mode liquid crystal cells 1 produced in Example 1 so that the slow axis of the optical compensation film 1 is parallel to the rubbing direction of the liquid crystal cell (that is, the retardation of the second retardation region). The phase axis is parallel to the slow axis direction of the liquid crystal molecules during black display), and the discotic liquid crystal application surface side is attached to the liquid crystal cell side. The transmission axis of this polarizing plate and the rubbing direction of the liquid crystal cell are parallel. Further, a second polarizing plate is attached to the other side of the liquid crystal cell so that the transmission axis is perpendicular to the rubbing direction of the liquid crystal cell and the surface of the protective film 1 is on the liquid crystal cell side. Produced.

(Measurement of leakage light of the manufactured liquid crystal display device)
The leakage light of the liquid crystal display device thus manufactured was measured. Light leakage when observed from the left oblique direction of 70 ° was 0.03%.

[Example 4]
A polarizing film was prepared by adsorbing iodine to a stretched polyvinyl alcohol film. A commercially available cellulose acetate film (Fujitac T40UZ, manufactured by Fuji Photo Film Co., Ltd., thickness 40 μm, Re = 1 nm, Rth = 35 nm) with a polyvinyl alcohol adhesive on both sides of the polarizing film A polarizing plate was produced by using them together. A liquid crystal display device was produced in the same manner as in Example 3 except that this polarizing plate was used as the second polarizing plate.

(Measurement of leakage light of the manufactured liquid crystal display device)
The leakage light of the liquid crystal display device thus manufactured was measured. Leakage when observed from the left oblique direction of 70 ° was 0.09%.

[Comparative Example 1]
A commercially available polarizing plate (HLC2-5618, manufactured by Sanritz Co., Ltd.) was attached to both sides of the produced IPS mode liquid crystal cell 1 in a crossed Nicol arrangement to produce a liquid crystal display device. An optical compensation film was not used. In the liquid crystal display device, as in Example 1, the polarizing plate was attached so that the transmission axis of the upper polarizing plate was parallel to the rubbing direction of the liquid crystal cell. The leakage light of the liquid crystal display device thus manufactured was measured. The leakage light when observed from the left diagonal direction of 70 ° was 0.55%.

[Comparative Example 2]
Compared to the IPS mode liquid crystal cell 1 produced in Example 1, the optical compensation sheet 2 produced in Example 2 is such that its slow axis is orthogonal to the rubbing direction of the liquid crystal cell and the discotic liquid crystal application surface side is liquid crystal. Affixed to the cell side. Subsequently, a commercially available polarizing plate (HLC2-5618, manufactured by Sanritz Co., Ltd.) is attached on the optical compensation sheet 2 so that the transmission axis is parallel to the rubbing direction of the liquid crystal cell. The same polarizing plate was attached to the other side in a crossed Nicol arrangement to produce a liquid crystal display device. The leakage light of the liquid crystal display device thus manufactured was measured. The leakage light when observed from the left oblique direction of 70 ° was 1.52% and was extremely large.

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 First protective film for polarizing film 8 DESCRIPTION OF SYMBOLS 1 Polarizing film 9 Polarization transmission axis 10 of 1st polarizing film Optical compensation film 11 1st phase difference region 12 2nd phase difference region 13 Slow axis 14 of 2nd phase difference region 1st board | substrate 15 1st board | substrate rubbing direction 16 Liquid crystal Layer 17 Slow axis direction 18 of liquid crystal molecule Second substrate 19 Second substrate rubbing direction 20a, 20b Protective film for second polarizing film 21 Second polarizing film 22 Second polarizing film Polarized transmission axis

Claims (10)

A liquid crystal composed of a first polarizing film, an optical compensation film comprising a first retardation region in contact with the first polarizing film and a second retardation region in contact with the first retardation region, a first substrate, and a nematic liquid crystal material A liquid crystal display device in which a layer and a second substrate are arranged in this order, and the liquid crystal molecules of the nematic liquid crystal material are aligned in parallel to the surfaces of the pair of substrates during black display,
Using 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, Re = (nx−ny) × d
The in-plane retardation Re of the first retardation region defined by is 20 nm or less, and Rth = ((nx + ny) / 2−nz) × d
The retardation Rth in the thickness direction of the first retardation region defined by is composed of a composition containing a discotic liquid crystal compound in which the second retardation region is substantially vertically aligned, 2. A liquid crystal display device, wherein the slow axis of the two retardation region is parallel to the transmission axis of the first polarizing film and the slow axis direction of the liquid crystal molecules during black display. The liquid crystal display device according to claim 1, wherein Re of the second retardation region of the optical compensation film is 50 nm to 200 nm. The first retardation region is composed of a plurality of layers, a layer in contact with the second retardation region among the plurality of layers is an alignment film, and the second retardation region is at least a discotic liquid crystalline compound. 3. The liquid crystal display device according to claim 1, further comprising an air interface alignment agent that reduces a tilt angle of a director of the discotic liquid crystal compound on the air interface side. The liquid crystal display device according to claim 1, further comprising a second polarizing film on an outer side of the second substrate. 5. The liquid crystal display device according to claim 4, further comprising: a pair of protective films arranged with the second polarizing film interposed therebetween, wherein a thickness direction retardation Rth of the protective film closer to the liquid crystal layer is 40 nm or less. The liquid crystal display device described. 5. A pair of protective films disposed with the second polarizing film interposed therebetween, wherein a thickness direction retardation Rth of the protective film closer to the liquid crystal layer of the pair of protective films is 20 nm or less. 5. A liquid crystal display device according to 5. 7. The protective film according to claim 4, further comprising: a pair of protective films arranged with the second polarizing film interposed therebetween, wherein a thickness of the protective film on the side close to the liquid crystal layer of the pair of protective films is 10 to 60 μm. 2. A liquid crystal display device according to item 1. The liquid crystal according to any one of claims 4 to 7, wherein the protective film on the side close to the liquid crystal layer is a cellulose acetate film or a norbornene-based film among the pair of protective films arranged with the second polarizing film interposed therebetween. Display device. The pair of protective films arranged with the second polarizing film interposed therebetween, the protective film on the side close to the liquid crystal layer has a layer containing a rod-like liquid crystalline compound vertically aligned with the cellulose acetate film. The liquid crystal display device according to any one of the above. The said 1st phase difference area | region is comprised from several layers, The layer which contact | connects a 1st polarizing film among these several layers functions as a protective film of a 1st polarizing film. A liquid crystal display device according to 1.

Images