JP2006171383A - Optical compensation sheet, polarizer using the same, and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coating type optical compensation sheet which has superior optical compensation capability and has superior adherence between an optical anisotropic layer and an alignment layer. <P>SOLUTION: The optical compensation sheet has a transparent base, the alignment layer, formed by coating the transparent base with a solution having solvent composition of ≥20% water and drying it, and the optical anisotropic layer formed, on the surface of the alignment layer, of a composition, containing at least one kind of liquid crystalline compound having at least one polymerizable group and at least one kind of amphipathic compound having at least one polymerizable group. The front retardation (Re) of the optical anisotropic layer is not 0, and the retardation value measured by making light with a λ nm wavelength incident at +40° with respect to the normal direction of the optical compensation sheet about a lagging axis in a plane as a tilt axis (axis of rotation) and a retardation value, measured by making light with a λ nm wavelength incident at -40° with respect to the normal direction of the compensation sheet, as well, are substantially equal to each other. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical compensation sheet, a polarizing plate, and a liquid crystal display device. More specifically, the present invention relates to an optical compensation sheet and polarized light that contribute to improving the viewing angle characteristics of a liquid crystal display device, particularly a vertical alignment (VA) mode liquid crystal display device. The present invention relates to a plate and a liquid crystal display device with improved viewing angle characteristics. The present invention also relates to a method for producing an optical compensation sheet having a good optical compensation capability.

  CRT (Cathode Ray Tube) has been mainly used as a display device used for OA devices such as word processors, notebook personal computers, personal computer monitors, portable terminals, and televisions. In recent years, liquid crystal display devices have been widely used instead of CRTs because of their thinness, light weight, and low power consumption. The liquid crystal display device has a liquid crystal cell and a polarizing plate. The polarizing plate is composed of a protective film and a polarizing film, and is obtained by dyeing a polarizing film made of a polyvinyl alcohol film with iodine, stretching, and laminating both surfaces with a protective film. For example, in a transmissive liquid crystal display device, the polarizing plate is attached to both sides of the liquid crystal cell, and one or more optical compensation sheets may be disposed. On the other hand, in a reflective liquid crystal display device, a reflector, a liquid crystal cell, one or more optical compensation sheets, and a polarizing plate are arranged in this order. The liquid crystal cell includes a liquid crystal molecule, two substrates for encapsulating the liquid crystal molecule, and an electrode layer for applying a voltage to the liquid crystal molecule. A liquid crystal cell performs ON / OFF display depending on the alignment state of liquid crystal molecules, and can be applied to any of a transmission type, a reflection type, and a semi-transmission type, such as TN (Twisted Nematic), IPS (In-Plane Switching), Display modes such as OCB (Optically Compensatory Bend), VA (Vertically Aligned), ECB (Electrically Controlled Birefringence), and STN (Super Twisted Nematic) are proposed. However, the color and contrast that can be displayed by a conventional liquid crystal display device vary depending on the angle at which the LCD is viewed. For this reason, the viewing angle characteristics of liquid crystal display devices have not yet exceeded the performance of CRT.

  In recent years, as an LCD method for improving the viewing angle characteristics, nematic liquid crystal molecules having negative dielectric anisotropy are used, and the major axis of the liquid crystal molecules is aligned in a direction substantially perpendicular to the substrate without applying a voltage. A vertical alignment nematic liquid crystal display device (hereinafter referred to as VA mode) in which this is driven by a thin film transistor has been proposed (see Patent Document 1). This VA mode not only has excellent display characteristics when viewed from the front, but also exhibits a wide viewing angle characteristic by applying a viewing angle compensation phase difference plate. In the VA mode, a wider viewing angle characteristic can be obtained by using a negative uniaxial retardation plate (negative c-plate) having an optical axis in a direction perpendicular to the film surface. It is also known that a wider viewing angle characteristic can be realized by using a uniaxially oriented retardation plate (positive a-plate) having a positive refractive index anisotropy having a retardation value of 50 nm ( Non-patent document 1).

  However, when the number of retardation plates is increased in this way, the production cost increases. In addition, since a large number of films are bonded together, it tends to cause not only a decrease in yield but also a deterioration in display quality due to a shift in the bonding angle. Furthermore, since a plurality of films are used, the thickness increases, which may be disadvantageous for thinning the display device.

  Further, a stretched film is usually used for positive a-plate, but when a simple longitudinally stretched film is used, the slow axis of a-plate is the film transport (MD) direction. However, in the VA mode viewing angle compensation, the slow axis of the a-plate must be orthogonal to the MD direction which is the absorption axis of the polarizing plate. Rises significantly. As a method for solving this, it is possible to use a so-called laterally stretched film that is stretched in a direction orthogonal to MD (TD direction). However, the transversely stretched film is apt to cause distortion of a slow axis called bowing, and the yield is high. The cost increases because it does not increase. Furthermore, since an adhesive layer is used for lamination of stretched films, the adhesive layer contracts due to temperature and humidity changes, and defects such as peeling and warping between films may occur. As a method for improving these, a method of producing a-plate by applying a rod-like liquid crystal is known (see Patent Document 2).

  Furthermore, in recent years, a method using a biaxial retardation plate has been proposed instead of the combination of c-plate and a-plate (Non-patent Document 2). By using a biaxial retardation plate, there is an advantage that not only the contrast viewing angle but also the color can be improved. However, the biaxial stretching usually used to produce a biaxial retardation plate is a lateral Similar to stretching, uniform axis control over the entire region of the film is difficult, and the yield does not increase, resulting in an increase in cost.

Therefore, a method of producing a biaxial retardation plate without using stretching by a method of irradiating polarized light to a special cholesteric liquid crystal (Patent Document 3) or a method of irradiating polarized light to a special disc-shaped liquid crystal (Patent Document 4). Was proposed. By this method, various problems caused by stretching can be solved.
However, in the case of producing a retardation plate by applying liquid crystal, an alignment layer is required immediately below in order to align the liquid crystal. Even with an alignment layer having a reactive group, the adhesion to the liquid crystal layer was not sufficiently obtained, and there were not a few problems from the viewpoint of manufacturing suitability such as bonding to a polarizing plate and stability over time. .

Japanese Patent Laid-Open No. 2-176625 JP 2000-304930 A International Publication WO 03/054111 Japanese Patent Laid-Open No. 2002-6138 SID 97 DIGEST Pages 845-848 SID 2003 DIGEST, pages 1208-1211

  An object of the present invention is to provide a coating type optical compensation sheet having a good optical compensation ability and excellent adhesion between the optically anisotropic layer and the alignment layer, a method for stably producing the optical compensation sheet, and the method A polarizing plate and a liquid crystal display device using an optical compensation sheet are provided. In particular, it is to provide a device used for a VA mode liquid crystal display device.

(1) A transparent support, an alignment layer formed by applying and drying a solution having a solvent composition of 20% or more of water on the transparent support, and at least one polymerizable property on the surface of the alignment layer An optical compensation sheet having an optically anisotropic layer formed from a composition containing at least one kind of liquid crystal compound having a group and at least one kind of amphiphilic compound having at least one polymerizable group. The front retardation (Re) of the isotropic layer is not 0, and light having a wavelength of λ nm from a direction inclined + 40 ° with respect to the normal direction of the optical compensation sheet with the in-plane slow axis as the tilt axis (rotation axis). Measured by making light incident at a wavelength λ nm from a direction inclined by −40 ° with respect to the normal direction of the optical compensation sheet, with the retardation value measured by incidence and the in-plane slow axis as the tilt axis (rotation axis) Letter day The optical compensation sheet ® emission values are substantially equal.
(2) At least one of the liquid crystalline compounds is a rod-like liquid crystalline compound having at least one polymerizable group, and the optically anisotropic layer is a layer formed by polymerizing the polymerizable group. (1) Optical compensation sheet.
(3) At least one of the liquid crystal compounds is a discotic liquid crystal compound having at least one polymerizable group, and the optically anisotropic layer is a layer formed by polymerizing the polymerizable group. An optical compensation sheet according to (1).
(4) At least one of the liquid crystal compounds is a rod-like liquid crystal compound having at least one polymerizable group, the composition further contains a chiral agent, and the optically anisotropic layer contains the polymerizable group. The optical compensation sheet according to (1), which is a layer formed by polymerization reaction.
(5) The optical compensation sheet according to any one of (1) to (4), wherein the amphiphilic compound having at least one polymerizable group is a compound represented by the following general formula (I).

（式中、Ｚは重合性基、Ｘ¹は連結基及びＱは親水基を表す）。

(In the formula, Z represents a polymerizable group, X ¹ represents a linking group, and Q represents a hydrophilic group).

(6) The optical compensation sheet according to (5), wherein the amphiphilic compound having at least one polymerizable group is a compound represented by the following general formula (II).

（式中、Ｚは重合性基、Ｘ¹は連結基、及びＲ¹とＲ²はそれぞれ独立に、水素原子、又は置換もしくは無置換のアルキル基、アルケニル基、アルキニル基又はアリール基を表す）。

(In the formula, Z represents a polymerizable group, X ¹ represents a linking group, and R ¹ and R ² each independently represents a hydrogen atom, or a substituted or unsubstituted alkyl group, alkenyl group, alkynyl group or aryl group) .

(7) The optical compensation sheet according to (5) or (6), wherein Z is a group represented by the following general formula (III), or a group having an oxirane moiety or an oxetane moiety.

（式中、Ｒ³は水素原子またはメチル基を、Ｌ¹は単結合または二価の連結基を表す）。

(Wherein R ³ represents a hydrogen atom or a methyl group, and L ¹ represents a single bond or a divalent linking group).

(8) The optical compensation sheet according to any one of (5) to (7), wherein X ¹ is arylene.
(9) The optical compensation according to any one of (1) to (8), wherein the alignment layer comprises a polymer selected from a polyvinyl alcohol derivative having a polymerizable group in the side chain, a poly (meth) acrylate derivative, and a polysaccharide. Sheet.
(10) A step of forming an alignment layer by applying and drying a solution having a solvent composition of 20% or more of water on a transparent support, and a rod-like liquid crystal having at least one polymerizable group on the surface of the alignment layer A liquid crystal composition comprising at least one kind of a volatile compound, a chiral agent and at least one kind of an amphiphilic compound having at least one polymerizable group, and the molecules of the rod-like liquid crystalline compound are allowed to have an average tilt angle of less than 5 °. The method for producing an optical compensation sheet according to (1), wherein the step of cholesteric alignment and the step of irradiating polarized light to polymerize molecules of the rod-like liquid crystal compound to form an optically anisotropic layer are performed in this order.
(11) A step of forming an alignment layer by applying and drying a solution having a solvent composition of 20% or more of water on a transparent support, and a discotic having at least one polymerizable group on the surface of the alignment layer A liquid crystal composition containing at least one liquid crystal compound, a chiral agent and at least one amphiphilic compound having at least one polymerizable group is applied, and the molecules of the discotic liquid crystal compound have an average inclination of less than 5 °. The method for producing an optical compensation sheet according to (1), wherein the step of aligning at an angle and the step of irradiating polarized light to polymerize molecules of the discotic liquid crystal compound to form an optically anisotropic layer are performed in this order. .
(12) A polarizing plate having at least one optical compensation sheet according to any one of (1) to (9) and a polarizer.
(13) A liquid crystal display device having the optical compensation sheet of any one of (1) to (9) or the polarizing plate of (12).
(14) The liquid crystal display device according to (13), which is in a VA mode.

  In the present invention, by adding an amphiphilic compound having a polymerizable group to the optically anisotropic layer, sufficient adhesion to a support for practical use is imparted, and its production suitability and stability over time are improved. It is improving. In particular, the elution into the saponification bath during the saponification treatment during polarizing plate processing and the fact that film peeling does not occur have made it possible to produce an optical compensation sheet with excellent productivity. Furthermore, by using the optical compensation sheet of the present invention, it becomes possible to optically compensate a liquid crystal cell with the same configuration as a conventional liquid crystal display element, and the present invention further includes the optical anisotropic layer. In the liquid crystal display element, not only display quality but also a viewing angle is remarkably improved.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described in detail.
In the present specification, “to” is used to mean that the numerical values described before and after it are included as a lower limit value and an upper limit value.

  In this specification, the Re retardation value and the Rth retardation value are calculated based on the following. Re (λ) and Rth (λ) respectively represent in-plane retardation and retardation in the thickness direction at wavelength λ. Re (λ) is measured by making light having a wavelength of λ nm incident in the normal direction of the film in KOBRA 21ADH (manufactured by Oji Scientific Instruments). Rth (λ) is incident on light having a wavelength of λnm from the direction inclined by + 40 ° with respect to the normal direction of the film, with Re (λ) and the slow axis (determined by KOBRA 21ADH) as the tilt axis (rotation axis). The retardation value measured in this way, and the retardation value measured by making light of wavelength λ nm incident from a direction inclined −40 ° with respect to the film normal direction with the in-plane slow axis as the tilt axis KOBRA 21ADH is calculated based on the retardation value measured in (1). At this time, it is necessary to input an assumed value of average refractive index and a film thickness. KOBRA 21ADH calculates nx, ny, and nz in addition to Rth (λ). The average refractive index of 1.48 is used for cellulose acetate, but values of polymer films for typical optical applications other than cellulose acetate include cycloolefin polymer (1.52), polycarbonate (1.59), poly Values such as methyl methacrylate (1.49) and polystyrene (1.59) can be used. As the average refractive index value of other existing polymer materials, the polymer handbook (John Wiley & Sons, Inc.) and the catalog values of polymer films can be used. In addition, in the case of a material whose average refractive index is unknown, it can be measured using an Abbe refractometer. In this specification, λ refers to 545 ± 5 nm or 590 ± 5 nm unless otherwise specified.

  In this specification, “substantially” for the angle means that the error from the exact angle is within a range of less than ± 5 °. Furthermore, the error from the exact angle is preferably less than 4 °, more preferably less than 3 °. “Substantially equal” for retardation means that the retardation is within ± 10%. In addition, the measurement wavelength of the refractive index indicates an arbitrary wavelength in the visible light region unless otherwise specified. In the present specification, “visible light” means light having a wavelength of 400 to 700 nm.

[Optical compensation sheet]
FIG. 1 is a schematic sectional view of an example of the optical compensation sheet of the present invention. The optical compensation sheet of the present invention has an optically anisotropic layer 12 on a transparent support 11. Between the transparent support 11 and the optically anisotropic layer 12, an alignment layer 13 for controlling the alignment of liquid crystalline molecules in the optically anisotropic layer 12 is disposed. The alignment layer 13 is a layer formed by applying and drying a solution having a solvent composition of 20% or more of water. Since the optically anisotropic layer 12 is formed from a composition containing a liquid crystalline compound having a polymerizable group and an amphiphilic compound having a polymerizable group, the alignment layer 13 and the optically anisotropic layer 12 are The adhesiveness is high, and peeling and the like hardly occur at the time of washing treatment such as water washing and chemical treatment such as saponification treatment, and the handling property is good. Further, the optical properties of the optically anisotropic layer 12 are such that the front retardation (Re) is not 0, and the in-plane slow axis is the tilt axis (rotation axis) and + 40 ° with respect to the normal direction of the optical compensation sheet. A retardation value measured by making light of wavelength λ nm incident from an inclined direction, and a direction inclined by −40 ° with respect to the normal direction of the optical compensation sheet with the in-plane slow axis as the inclined axis (rotating axis) Since the retardation value measured by making light having a wavelength λ nm incident is adjusted to be substantially equal, a liquid crystal cell, particularly a VA mode liquid crystal cell can be compensated accurately. “Re is not 0” means that Re is not less than 5 nm.

[Polarizer]
2A to 2D are schematic sectional views of a polarizing plate having the optical compensation sheet of the present invention. In general, the polarizing plate can be prepared by dyeing a polarizing film made of a polyvinyl alcohol film with iodine and performing stretching to obtain the polarizing film 21, and laminating protective films 22 and 23 on both sides thereof. it can. Since the optical compensation sheet of the present invention has a support made of a polymer film or the like that supports the optically anisotropic layer, this support can be used as it is for at least one of the protective films 22 and 23. At this time, even if the optically anisotropic layer 12 is disposed on the polarizing layer 21 side (that is, the optically anisotropic layer 12 is closer to the polarizing layer 21 than the support 11), the optically anisotropic layer 12 is on the opposite side of the polarizing layer 21 ( That is, the optically anisotropic layer 12 may be disposed farther from the support 11 than the polarizing layer 21, but as shown in FIG. 2A, the optically anisotropic layer 12 includes the polarizing layer 21. It is preferable that it exists in the other side. Further, as shown in FIG. 2 (b), it is also possible to bond to the outside of one protective film 22 of the polarizing layer 21 via an adhesive or the like.

  2C and 2D are configuration examples of a polarizing plate in which another functional layer 24 is further arranged on the polarizing plate having the configuration shown in FIG. FIG. 2C is a configuration example in which another functional layer 24 is disposed on the protective film 23 disposed on the opposite side with the optical compensation sheet of the present invention and the polarizing layer 21 in between. ) Is a configuration example in which another functional layer 24 is arranged on the optical compensation sheet of the present invention. Examples of other functional layers are not particularly limited, and examples thereof include functional layers that impart various characteristics, such as λ / 4 layers, antireflection layers, and hard coat layers. These layers may be bonded together with, for example, an adhesive as a member such as a λ / 4 plate, an antireflection film, or a hard coat film. In the configuration example of FIG. Another functional layer 24 may be formed on the sheet (the optically anisotropic layer 12) and then bonded to the polarizing layer 21. Further, the protective film 23 itself on the side opposite to the optical compensation sheet of the present invention can be made into other functional films such as a λ / 4 plate, an antireflection film, and a hard coat film.

  When producing a polarizing plate by laminating a polarizing film and a protective film, a total of three films of a pair of protective film and polarizing film can be bonded together in a roll-to-roll manner. This roll-to-roll is a preferable method as a manufacturing process of a polarizing plate because it is difficult to cause dimensional change and curling of the polarizing plate as well as productivity, and can impart high mechanical stability.

[Liquid Crystal Display]
FIG. 3 shows an example of the liquid crystal display device of the present invention. The liquid crystal display device includes a liquid crystal cell 35 having a nematic liquid crystal sandwiched between upper and lower electrode substrates, and a pair of polarizing plates 36 and 37 disposed on both sides of the liquid crystal cell, and at least one of the polarizing plates. Uses the polarizing plate of the present invention shown in FIG. When using the polarizing plate of this invention, it arrange | positions so that an optically anisotropic layer may exist between a polarizing layer and the electrode substrate of a liquid crystal cell. Nematic liquid crystal molecules are controlled so as to be in a predetermined alignment state by providing an alignment layer applied on the electrode substrate and a rubbing process on the surface or a structure such as a rib.

  One or more light control films 34 such as a brightness enhancement film and a diffusion film may be provided below the liquid crystal cell sandwiched between the polarizing plates. Furthermore, the light control film has a reflection plate 32 and a light guide plate 33 for irradiating light emitted from the cold cathode tubes 31 to the front. Instead of a backlight unit comprising a cold cathode tube and a light guide plate, recently, a direct type backlight in which several cold cathode tubes are arranged under a liquid crystal cell, an LED backlight using an LED as a light source, or an organic EL Backlights that emit surface light using inorganic EL or the like are also used, but any of the optical films of the present invention is also effective in backlights.

  Further, although not shown in the figure, in the reflective liquid crystal display device, only one polarizing plate is required on the observation side, and a reflective film is provided on the back surface of the liquid crystal cell or on the inner surface of the lower substrate of the liquid crystal cell. . Of course, it is also possible to provide a front light using the light source on the liquid crystal cell observation side. Further, a transflective type in which a transmissive portion and a reflective portion are provided in one pixel of the display device is also possible.

Next, materials used for manufacturing the optical compensation sheet of the present invention, manufacturing methods, and the like will be described in detail.
The optical compensation sheet of the present invention has a transparent support, the alignment layer, and the optically anisotropic layer, and the optically anisotropic layer expands the contrast viewing angle of the liquid crystal display device, and the image of the liquid crystal display device Contributes to eliminating coloring. In the optical compensation sheet of the present invention, the support of the optically anisotropic layer also serves as a protective film for the polarizing plate, or the optically anisotropic layer also serves as a protective film for the polarizing plate, The number of components can be reduced. In other words, this aspect contributes to the thinning of the liquid crystal display device.

  In the present invention, an optically anisotropic layer made of a liquid crystalline compound is formed on an optically uniaxial or biaxial transparent support made of a high molecular polymer, thereby greatly improving the optical characteristics of the liquid crystal display device. be able to.

[Optically anisotropic layer made of liquid crystal compound]
The optical compensation sheet of the present invention is an optical compensation sheet formed from a composition containing at least one liquid crystalline compound having at least one polymerizable group and at least one amphiphilic compound having at least one polymerizable group. Has an anisotropic layer. The optically anisotropic layer contributes to optical compensation of the liquid crystal cell. Of course, the optically anisotropic layer alone may have sufficient optical compensation ability, or may be an aspect satisfying the optical characteristics required for optical compensation in combination with other layers (for example, a support). Liquid crystal compounds can be classified into rod-shaped and disc-shaped types based on their molecular shapes. In addition, there are low and high molecular types, respectively. In addition, there are low and high molecular types, respectively. Polymer generally refers to a polymer having a degree of polymerization of 100 or more (Polymer Physics / Phase Transition Dynamics, Masao Doi, 2 pages, Iwanami Shoten, 1992). In the present invention, any liquid crystal compound can be used, but a rod-like liquid crystal compound or a discotic liquid crystal compound is preferably used. Two or more kinds of rod-like liquid crystal compounds, two or more kinds of discotic liquid crystal compounds, or a mixture of a rod-like liquid crystal compound and a discotic liquid crystal compound may be used. In the present invention, any liquid crystal compound can be used, but a rod-like liquid crystal compound or a discotic liquid crystal compound is preferably used. In the case of using a mixture, it is sufficient that at least one kind has a polymerizable group. The thickness of the optically anisotropic layer is preferably 0.1 to 20 μm, and more preferably 0.5 to 10 μm.

  Examples of rod-like liquid crystalline compounds include azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, alkoxy-substituted phenylpyrimidines. , Phenyldioxanes, tolanes and alkenylcyclohexylbenzonitriles are preferably used. Not only the above low-molecular liquid crystalline compounds but also high-molecular liquid crystalline compounds can be used. The polymer liquid crystalline compound is a polymer compound obtained by polymerizing a rod-like liquid crystalline compound having a low molecular polymerizable group. The rod-like liquid crystalline compound having a low molecular polymerizable group that is particularly preferably used is a rod-like liquid crystalline compound represented by the following general formula (IV).

Formula (IV): Q ¹ -L ¹ -A ¹ -L ³ -ML ⁴ -A ² -L ² -Q ²
Wherein, Q ¹ and Q ² each independently is a polymerizable group, L ^1, the L ^2, L ³ and L ⁴ each independently represent a single bond or a divalent linking group, L ³ and At least one of L ⁴ is preferably —O—CO—O—. A ¹ and A ² each independently represent a spacer group having 2 to 20 carbon atoms. M represents a mesogenic group.

Hereinafter, the rod-like liquid crystal compound having a polymerizable group represented by the general formula (IV) will be described in more detail. In the formula, Q ¹ and Q ² are each independently a polymerizable group. The polymerization reaction of the polymerizable group is preferably addition polymerization (including ring-opening polymerization) or condensation polymerization. In other words, the polymerizable group is preferably a polymerizable group capable of addition polymerization reaction or condensation polymerization reaction. Examples of polymerizable groups are shown below.

Examples of the divalent linking group represented by L ¹ , L ² , L ³ and L ⁴ include —O—, —S—, —CO—, —NR ² —, —CO—O—, and —O—CO. —O—, —CO—NR ² —, —NR ² —CO—, —O—CO—, —O—CO—NR ² —, —NR ² —CO—O—, and NR ² —CO—NR ^2. A divalent linking group selected from the group consisting of-is preferred. R ² is an alkyl group having 1 to 7 carbon atoms or a hydrogen atom. In this case, it is preferable that at least one of L ³ and L ⁴ is —O—CO—O— (carbonate group). In the formula (IV), Q ¹ -L ¹ and Q ² -L ² -are CH ₂ ═CH—CO—O—, CH ₂ ═C (CH ₃ ) —CO—O—, and CH ₂ ═C ( Cl) -CO-O-CO- O- are _{preferable, CH 2 = CH-CO-} O- is most preferable.

A ¹ and A ² represent spacer groups having 2 to 20 carbon atoms. An aliphatic group having 2 to 12 carbon atoms is preferable, and an alkylene group is particularly preferable. The spacer group is preferably chain-like and may contain oxygen atoms or sulfur atoms that are not adjacent to each other. The spacer group may have a substituent and may be substituted with a halogen atom (fluorine, chlorine, bromine), a cyano group, a methyl group, or an ethyl group.

Examples of the mesogenic group represented by M include all known mesogenic groups. In particular, a group represented by the following general formula (V) is preferable.
Formula (V): - (- W 1 -L 5) n -W 2 -
In the formula, W ¹ and W ² each independently represent a divalent cycloaliphatic group, a divalent aromatic group or a divalent heterocyclic group, L ⁵ represents a single bond or a linking group, and Specific examples of the group include specific examples of the group represented by L ^{1 to} L ⁴ in the formula (IV), —CH ₂ —O—, and —O—CH ₂ —. n represents 1, 2 or 3.

W ¹ and W ² include 1,4-cyclohexanediyl, 1,4-phenylene, pyrimidine-2,5-diyl, pyridine-2,5-diyl, 1,3,4-thiadiazole-2,5-diyl. 1,3,4-oxadiazole-2,5-diyl, naphthalene-2,6-diyl, naphthalene-1,5-diyl, thiophene-2,5-diyl, pyridazine-3,6-diyl It is done. In the case of 1,4-cyclohexanediyl, there are trans isomers and cis isomers, but either isomer may be used, and a mixture in any proportion may be used. More preferably, it is a trans form. W ¹ and W ² may each have a substituent. Examples of the substituent include a halogen atom (fluorine, chlorine, bromine, iodine), a cyano group, an alkyl group having 1 to 10 carbon atoms (methyl group, ethyl group, propyl group, etc.), and an alkoxy group having 1 to 10 carbon atoms. (Methoxy group, ethoxy group, etc.), C1-10 acyl group (formyl group, acetyl group, etc.), C1-10 alkoxycarbonyl group (methoxycarbonyl group, ethoxycarbonyl group, etc.), carbon atom Examples thereof include an acyloxy group having 1 to 10 (acetyloxy group, propionyloxy group, etc.), nitro group, trifluoromethyl group, difluoromethyl group and the like.

  Preferred examples of the basic skeleton of the mesogenic group represented by the general formula (V) are shown below. These may be substituted with the above substituents.

  Examples of the compound represented by the general formula (IV) are shown below, but the present invention is not limited thereto. The compound represented by the general formula (IV) can be synthesized, for example, by the method described in JP-T-11-513019.

  Discotic liquid crystalline compounds that can be used in the present invention include various documents (C. Destrade et al., Mol. Cryst. 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); 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 disk-shaped core of a disk-shaped liquid crystalline compound can be considered. However, when a polymerizable group is directly bonded to a disk-shaped core, the alignment state can be 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 general formula (VI).
Formula (VI): 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.

  In the formula (VI), preferred specific examples of the discotic core (D), the divalent linking group (L), and the polymerizable group (P) are (D1) described in JP-A No. 2001-4837, respectively. To (D15), (L1) to (L25), (P1) to (P18), and the discotic core (D), divalent linking group (L) and polymerizable group ( The contents regarding P) can be preferably applied here.

  When using a rod-like liquid crystalline compound having a polymerizable group, in order to develop biaxiality, the cholesteric alignment or the hybrid cholesteric alignment twisted while gradually changing the tilt angle in the thickness direction may be distorted by polarized light irradiation. is necessary. Examples of the method of distorting the alignment by irradiation with polarized light include a method using a dichroic liquid crystalline polymerization initiator (International Publication WO03 / 054111) and a rod-like liquid crystalline compound having a photoalignable functional group such as a cinnamoyl group in the molecule. (Japanese Unexamined Patent Application Publication No. 2002-6138).

  When using a discotic liquid crystalline compound having a polymerizable group, it may be fixed in any alignment state of horizontal alignment, vertical alignment, tilt alignment, and twist alignment, but is symmetrical with respect to the normal direction of the film. There are preferred horizontal orientation, vertical orientation, and twist orientation, and horizontal orientation is most preferred. Horizontal alignment means that the disk surface of the core of the discotic liquid crystalline compound is parallel to the horizontal surface of the transparent support, but does not require strictly parallel. An orientation with an inclination angle of less than 10 degrees is meant.

  The Re of the optically anisotropic layer is preferably 5 to 250 nm, more preferably 5 to 100 nm, and most preferably 10 to 80 nm. Rth is preferably 30 to 500 nm in total with Rth of the transparent support, more preferably 40 to 400 nm, and most preferably 100 to 350 nm.

  In the case of laminating two or more optically anisotropic layers, the combination of liquid crystalline compounds is not particularly limited, and a laminate of layers made of a discotic liquid crystalline compound, a laminate of layers made of a rod-like liquid crystalline compound. Or a laminate of a layer made of a discotic liquid crystalline compound and a layer made of a rod-like liquid crystalline compound. The combination of the alignment states of the layers is not particularly limited, and optically anisotropic layers having the same alignment state may be stacked, or optically anisotropic layers having different alignment states may be stacked.

[Amphiphilic compound having at least one polymerizable group]
The composition used for forming the optically anisotropic layer contains at least one amphiphilic compound having at least one polymerizable group. For example, when preparing the coating liquid for forming the optically anisotropic layer, the amphiphilic compound is dissolved in a solvent together with the liquid crystalline compound and applied to the surface of the alignment layer. The substituent of the amphiphilic compound interacts with a functional group of the alignment layer (for example, a hydroxyl group when the alignment layer is mainly composed of polyvinyl alcohol or a derivative thereof) and is adsorbed on the interface of the alignment layer. Or penetrating the alignment layer, and then polymerizing the amphiphilic compound having a polymerizable group and the liquid crystalline compound having a polymerizable group, for example, by irradiation with ultraviolet rays or the like, to form an optically anisotropic layer In addition, the adhesion between the alignment layer and the optically anisotropic layer can be further enhanced. Therefore, the amphiphilic compound preferably has a substituent having an affinity for the functional group of the polymer constituting the alignment layer.

  A preferred example of the amphiphilic compound having a polymerizable group used in the present invention is represented by the following general formula (I).

In general formula (I), X ¹ represents a divalent linking group, and examples of the linking group include a single bond, —O—, —CO—, —NH—, —CO—NH—, —COO—, A divalent group selected from —O—COO—, an alkylene group, an arylene group, a heteroaryl group, and a combination thereof is preferable, and a substituted or unsubstituted arylene group is more preferable.

  In general formula (I), Z represents a polymerizable group, preferably a group represented by the following general formula (III), or a group having an oxirane moiety or an oxetane moiety.

In general formula (III), R < ³ > is a hydrogen atom or a methyl group, and a hydrogen atom is preferable. L ¹ is a single bond, or —O—, —CO—, —NH—, —CO—NH—, —COO—, —O—COO—, an alkylene group, an arylene group, a heterocyclic group, and combinations thereof And is preferably a single bond, —CO—NH— or —COO—, more preferably a single bond or —CO—NH—.

  Specific examples of Z in the general formula (II) include an acrylate group, a methacrylate group, a styryl group, a vinyl ketone group, a butadiene group, a vinyl ether group, an oxirane group, an aziridinyl group, and an oxetane group, preferably an acrylate group. , A methacrylate group, a styryl group, an oxirane group or an oxetane group, and most preferably an acrylate group, a methacrylate group or a styryl group.

  In general formula (I), Q represents a hydrophilic group. Here, the hydrophilic group is an atomic group that forms a weak bond with a water molecule by electrostatic interaction, hydrogen bond, or the like and has an affinity for water. The hydrophilic group is preferably a group that can be adsorbed and bonded to the alignment layer, particularly when the alignment layer has a hydroxyl group (for example, when polyvinyl alcohol or a derivative thereof is a main component). Groups that can be bonded to groups are preferred. Specifically, groups such as —SiX (X is halogen or alkoxy), aldehyde, ester, carboxyl, isocyanate, epoxy, oxetane, boronic acid, or boronic acid ester are preferable.

  Among the compounds represented by the general formula (I), compounds represented by the following general formula (II) are more preferable.

In general formula (II), R ¹ and R ² each independently represent a hydrogen atom, or a substituted or unsubstituted alkyl group, alkenyl group, alkynyl group or aryl group. R ¹ and R ² may combine to form a ring. Moreover, X < ¹ > and Z in general formula (II) are synonymous with X < ¹ > and Z in general formula (I), respectively.

  Specific examples of the alkyl group include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, hexadecyl, Octadecyl group, eicosyl group, isopropyl group, isobutyl group, sec-butyl group, tert-butyl group, isopentyl group, neopentyl group, 1-methylbutyl group, isohexyl group, 2-methylhexyl group, cyclopentyl group, cyclohexyl group, 1- Examples thereof include linear, branched, or cyclic alkyl groups such as an adamantyl group and 2-norbornyl group. Specific examples of the alkenyl group include linear, branched, such as vinyl group, 1-propenyl group, 1-butenyl group, 1-methyl-1-propenyl group, 1-cyclopentenyl group and 1-cyclohexenyl group. Or a cyclic alkenyl group.

  Specific examples of the alkynyl group include ethynyl group, 1-propynyl group, 1-butynyl group, 1-octynyl group and the like.

The aromatic ring contained in the aryl group may be composed of only carbon, may contain a heterocycle, or may be one or both condensed rings. That is, in the present specification, the “aryl group” includes a heteroaryl group. Specific examples include a benzene ring, two or more, preferably 2 to 4 condensed rings of benzene rings, a condensed ring of a benzene ring and an unsaturated five-membered ring, and the like. Specific examples include a phenyl group, a naphthyl group, an anthryl group, a phenanthryl group, an indenyl group, an acenaphthenyl group, a fluorenyl group, and a pyrenyl group.
The heteroaryl group is a heteroaryl group containing at least one heteroatom selected from the group consisting of a nitrogen atom, an oxygen atom and a sulfur atom, and 1 heteroatom selected from the group consisting of a nitrogen atom, an oxygen atom and a sulfur atom. Examples include a heteroaryl group obtained by removing one hydrogen atom on a heteroaromatic ring containing at least one heteroaromatic ring. Specific examples of the heteroaromatic ring containing one or more heteroatoms selected from the group consisting of nitrogen atom, oxygen atom and sulfur atom include pyrrole, furan, thiophene, pyrazole, imidazole, triazole, oxazole, isoxazole and oxadiazole. , Thiazole, thiadiazole, indole, carbazole, benzofuran, dibenzofuran, thianaphthene, dibenzothiophene, indazolebenzimidazole, anthranyl, benzisoxazole, benzoxazole, benzothiazole, purine, pyridine, pyridazine, pyrimidine, pyrazine, triazine, quinoline, acridine, Examples thereof include isoquinoline, phthalazine, quinazoline, quinoxaline, naphthyridine, phenanthroline, and pteridine.

One or more of these alkyl groups, alkenyl groups, alkynyl groups or aryl groups may be substituted with any substituent. Examples of the substituent include monovalent non-metallic atomic groups excluding hydrogen, halogen atoms (—F, —Br, —Cl, —I), hydroxyl groups, alkoxy groups, aryloxy groups, mercapto groups, alkylthio groups. , Arylthio group, alkyldithio group, aryldithio group, amino group, N-alkylamino group, N, N-dialkylamino group, N-arylamino group, N, N-diarylamino group, N-alkyl-N-aryl Amino group, acyloxy group, carbamoyloxy group, N-alkylcarbamoyloxy group, N-arylcarbamoyloxy group, N, N-dialkylcarbamoyloxy group, N, N-diarylcarbamoyloxy group, N-alkyl-N-arylcarbamoyl Oxy, alkylsulfoxy, arylsulfoxy, acylthio Group, acylamino group, N-alkylacylamino group, N-arylacylamino group, ureido group, N′-alkylureido group, N ′, N′-dialkylureido group, N′-arylureido group, N ′, N '-Diarylureido group, N'-alkyl-N'-arylureido group, N-alkylureido group, N-arylureido group, N'-alkyl-N-alkylureido group, N'-alkyl-N-arylureido Group, N ′, N′-dialkyl-N-alkylureido group, N ′, N′-dialkyl-N-arylureido group, N′-aryl-N-alkylureido group, N′-aryl-N-arylureido Group, N ′, N′-diaryl-N-alkylureido group, N ′, N′-diaryl-N-arylureido group, N′-alkyl-N′-aryl-N-alkyl Raid group, N′-alkyl-N′-aryl-N-arylureido group, alkoxycarbonylamino group, aryloxycarbonylamino group, N-alkyl-N-alkoxycarbonylamino group, N-alkyl-N-aryloxycarbonyl Amino group, N-aryl-N-alkoxycarbonylamino group, N-aryl-N-aryloxycarbonylamino group, formyl group, acyl group, carboxyl group and its conjugate base group, alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl Group, N-alkylcarbamoyl group, N, N-dialkylcarbamoyl group, N-arylcarbamoyl group, N, N-diarylcarbamoyl group, N-alkyl-N-arylcarbamoyl group, alkylsulfinyl group, arylsulfinyl group, alkyl Sulfonyl group, arylsulfonyl group, sulfo group (—SO ₃ H) and its conjugate base group, alkoxysulfonyl group, aryloxysulfonyl group, sulfinamoyl group, N-alkylsulfinamoyl group, N, N-dialkylsulfinamoyl group N-arylsulfinamoyl group, N, N-diarylsulfinamoyl group, N-alkyl-N-arylsulfinamoyl group, sulfamoyl group, N-alkylsulfamoyl group, N, N-dialkylsulfamoyl group Group, N-arylsulfamoyl group, N, N-diarylsulfamoyl group, N-alkyl-N-arylsulfamoyl group, N-acylsulfamoyl group and its conjugate base group, N-alkylsulfonylsulfur group Famoiru group _{(-SO 2 NHSO 2 (alkyl)} ) and its conjugated base group N- aryl acylsulfamoyl group _{(-SO 2 NHSO 2 (aryl)} ) and its conjugated base group, N- alkylsulfonylcarbamoyl group (-CONHSO ₂ (alkyl)) and its conjugated base group, N- aryl sulfonyl carbamoyl group (—CONHSO ₂ (aryl)) and its conjugate base group, alkoxysilyl group (—Si (Oalkyl) ₃ ), aryloxysilyl group (—Si (Oaryl) ₃ ), hydroxysilyl group (—Si (OH) ₃ ) And its conjugate base group, phosphono group (—PO ₃ H ₂ ) and its conjugate base group, dialkylphosphono group (—PO ₃ (alkyl) ₂ ), diarylphosphono group (—PO ₃ (aryl) ₂ ), alkyl Arylphosphono group (—PO ₃ (alkyl) (aryl)), monoalkylphosphono group (—PO ₃ H (alkyl)) and its conjugate base group, monoarylphosphono group (—PO ₃ H (aryl)) and its conjugate base group, phosphonooxy group (—OPO ₃ H ₂ ) and its conjugate base group, dialkylphosphonooxy Group (—OPO ₃ (alkyl) ₂ ), diarylphosphonooxy group (—OPO ₃ (aryl) ₂ ), alkylarylphosphonooxy group (—OPO ₃ (alkyl) (aryl)), monoalkylphosphonooxy group (—OPO ₃ H (alkyl)) and its conjugate base group, monoarylphosphonooxy group (—OPO ₃ H (aryl)) and its conjugate base group, cyano group, nitro group, aryl group, alkenyl group, alkynyl group Is mentioned. In addition, these substituents may combine with each other or with a substituted hydrocarbon group to form a ring, if possible.

R ¹ and R ² in the general formula (II) are preferably hydrogen atoms.

  Specific examples of the amphiphilic compound having a preferable polymerizable group represented by the general formula (I) are shown below, but the present invention is not limited thereto.

  The optically anisotropic layer is formed by applying a coating solution containing the liquid crystalline compound, the amphiphilic compound, and, if desired, the following polymerization initiator and other additives onto the alignment layer. Is preferred. 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).

[Fixation of alignment state of liquid crystalline compounds]
It is preferable to fix the aligned liquid crystal compound molecules while maintaining the alignment state. The immobilization is preferably carried out by a polymerization reaction of a polymerizable group 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, and a photopolymerization reaction is more preferable. 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 aromatics. Group acyloin compounds (described in US Pat. No. 2,722,512), polynuclear quinone compounds (described in US Pat. Nos. 3,046,127 and 2,951,758), combinations of triarylimidazole dimers and p-aminophenyl ketone (US patents) No. 3549367), acridine and phenazine compounds (JP-A-60-105667, US Pat. No. 4,239,850) and oxadiazole compounds (US Pat. No. 4,221,970).

The amount of the photopolymerization initiator used is preferably 0.01 to 20% by weight, more preferably 0.5 to 5% by weight, based on the solid content of the coating solution. Light irradiation for the polymerization of the liquid crystalline compound is preferably performed using ultraviolet rays. The irradiation energy is preferably ^{20mJ / cm 2 ~10J / 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.

[Optical alignment by polarized irradiation]
The optically anisotropic layer of the present invention can generate in-plane retardation by irradiation with polarized light. This polarized light irradiation may be performed at the same time as the photopolymerization process in the above-mentioned orientation fixing, or may be further fixed by non-polarized light after first polarized light irradiation, or fixed first by non-polarized light irradiation. The irradiation with polarized light may be performed after conversion. In order to obtain a large retardation, it is preferable to irradiate polarized light alone or first. The polarized light irradiation is preferably performed in an inert gas atmosphere having an oxygen concentration of 3% or less, more preferably 0.5% or less. For polarized light irradiation, ultraviolet polarized light irradiation is preferable, particularly polarized light irradiation having a peak at 365 ± 10 nm is preferable, and polarized light irradiation having a peak at 365 ± 5 nm is more preferable. The irradiation energy is preferably ^{20mJ / cm 2 ~10J / cm 2} , further preferably 100 to 800 mJ / cm ^2. The illuminance is preferably 20 to 1000 mW / cm ^2, more preferably 50 to 500 mW / cm ^2, further preferably 100 to 350 mW / cm ^2. Although there is no restriction | limiting in particular about the kind of liquid crystalline compound hardened | cured by polarized light irradiation, The liquid crystalline compound which has an ethylenically unsaturated group as a polymeric group is preferable.
Note that the optically anisotropic layer exhibiting in-plane retardation generated by photo-alignment by polarized light irradiation is particularly excellent for optically compensating a VA mode liquid crystal display device.

[Horizontal alignment agent]
The liquid crystalline compound forming the optically anisotropic layer can be substantially horizontally aligned by using at least one of the compounds represented by the following general formulas (VII) to (IX). In the present invention, “horizontal alignment” means that in the case of a rod-like liquid crystal, the molecular long axis is parallel to the horizontal plane of the transparent support. In the case of a disc-like liquid crystal, the disc surface of the core of the disc-like liquid crystal compound. And the horizontal plane of the transparent support is parallel, but it is not required to be strictly parallel, and in this specification, an inclination angle with the horizontal plane is less than 10 degrees. To do. The inclination angle is preferably 0 to 5 degrees, more preferably 0 to 3 degrees, further preferably 0 to 2 degrees, and most preferably 0 to 1 degree.

  In the present invention, the addition amount of the compounds represented by the general formulas (VII) to (IX) is preferably 0.01 to 20% by weight, and 0.01 to 10% by weight of the amount of the liquid crystal compound. More preferred is 0.02 to 1% by weight. In addition, the compounds represented by the general formulas (VII) to (IX) may be used alone or in combination of two or more.

  Hereinafter, the following general formulas (VII) to (IX) will be described in order.

In the formula, R ¹ , R ² and R ³ each independently represent a hydrogen atom or a substituent, and X ¹ , X ² and X ^{3 each} represent a single bond or a divalent linking group. The substituent represented by each of R ^{1 to} R ³ is preferably a substituted or unsubstituted alkyl group (more preferably an unsubstituted alkyl group or a fluorine-substituted alkyl group), an aryl group (particularly a fluorine-substituted alkyl). An aryl group having a group is preferred), a substituted or unsubstituted amino group, an alkoxy group, an alkylthio group, and a halogen atom. The divalent linking groups represented by X ¹ , X ² and X ³ are each an alkylene group, an alkenylene group, a divalent aromatic group, a divalent heterocyclic residue, —CO—, —NR ^a — ( R ^a is ^a divalent linking group selected from the group consisting of an alkyl group having 1 to 5 carbon atoms or a hydrogen atom), —O—, —S—, —SO—, —SO ₂ —, and combinations thereof. Preferably there is. The divalent linking group is selected from the group consisting of an alkylene group, a phenylene group, —CO—, —NR ^a —, —O—, —S—, and —SO ₂ —. It is more preferable that the divalent linking group is a combination of at least two groups. The alkylene group preferably has 1 to 12 carbon atoms. The alkenylene group preferably has 2 to 12 carbon atoms. The number of carbon atoms of the divalent aromatic group is preferably 6-10.

In the formula, R represents a substituent, and m represents an integer of 0 to 5. When m represents an integer greater than or equal to 2, several R may be same or different. Preferred substituents for R are the same as those recited as preferred ranges for the substituents represented by R ¹ , R ² , and R ³ . m preferably represents an integer of 1 to 3, particularly preferably 2 or 3.

In the formula, R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ and R ⁹ each independently represent a hydrogen atom or a substituent. The substituents represented by R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ and R ⁹ are each preferably a substituent represented by R ¹ , R ² and R ³ in the general formula (I). It is listed as a thing.

[Alignment layer]
In the present invention, the alignment layer is formed by applying and drying a solution having a solvent composition of 20% or more of water. In general, the alignment layer can be provided by means such as a rubbing treatment of an organic compound (preferably a polymer). The rubbing process is carried out by rubbing the surface of the polymer layer several times in a certain direction with paper or cloth. On the alignment layer of the present invention, a solution comprising a liquid crystal composition compound is applied and dried to give an optically anisotropic layer, but the surface of the alignment layer rubbed with the solvent is not dissolved.
The alignment layer is provided on the transparent support and has a function of defining the alignment direction of the liquid crystalline compound provided thereon by coating or the like, and the alignment provides an optical axis inclined from the optical compensation sheet. In the present invention, the alignment layer is a polymer layer subjected to an alignment treatment such as a rubbing treatment, and the polymer has a group having vinyl, oxirane, aziridinyl, or aryl. The polymer is preferably polyvinyl alcohol or modified polyvinyl alcohol. In polyvinyl alcohol, at least one hydroxyl group is substituted with a group having a vinyl moiety, an oxirane moiety or an aziridinyl moiety. In general, the above-mentioned moiety is composed of a polymer chain (carbon atom) of polyvinyl alcohol, an ether bond (—O—), a urethane bond (—OCONH—), an acetal bond ((—O—) ₂ CH—) or an ester bond (— OCO-). A urethane bond, an acetal bond or an ester bond is preferred. Vinyl, oxirane, aziridinyl or aryl is preferably bonded indirectly to polyvinyl alcohol via the above bond, that is, the group having the above moiety is preferably bonded to polyvinyl alcohol together with the bonding group. .

  By reacting a compound having a group to be introduced into polyvinyl alcohol or modified polyvinyl alcohol with polyvinyl alcohol, the polyvinyl alcohol having a specific group of the present invention can be obtained. Polyvinyl alcohol or modified polyvinyl alcohol generally has a saponification degree of 70 to 100%. The polymerization degree is preferably in the range of 100 to 3000. The saponification degree is preferably in the range of 80 to 100%, particularly preferably 85 to 95%. Moreover, as a polymerization degree, the range of 100-3000 is preferable. Examples of polyvinyl alcohol or modified polyvinyl alcohol preferably used in the present invention are described in JP-A-9-152509.

[Transparent support]
As the transparent support for the optically anisotropic layer, it is preferable to use a polymer film having a light transmittance of 80% or more. The thickness of the transparent support is preferably 10 to 500 μm, more preferably 20 to 200 μm, and most preferably 35 to 110 μm.

  The glass transition temperature (Tg) of the transparent support of the present invention is appropriately determined according to the purpose of use. The glass transition temperature of the resin is preferably 70 ° C. or higher, more preferably 75 ° C. to 200 ° C., and particularly preferably 80 ° C. to 180 ° C. When a resin in this range is employed, heat resistance and molding processability are highly balanced, which is preferable.

  The Re of the transparent support is preferably adjusted to a range of −200 to 100 nm, and Rth is preferably adjusted to a range of −100 to 100 nm. Re is more preferably −50 to 30 nm, and most preferably −30 to 20 nm. The birefringence (Δn: nx−ny) of the cellulose ester film is preferably in the range of 0 to 0.02. The birefringence {(nx + ny) / 2−nz} in the thickness direction of the cellulose ester film is preferably in the range of 0 to 0.04. In the present specification, negative Re means that the in-plane slow axis of the transparent support is in the TD direction, and negative Rth means that the refractive index in the thickness direction is larger than the in-plane average refractive index.

  Examples of the polymer constituting the transparent support include cellulose ester (eg, cellulose acetate, cellulose propionate, cellulose butyrate), polyolefin (eg, norbornene-based polymer), poly (meth) acrylic acid ester (eg, poly Methyl methacrylate), polycarbonate, polyester and polysulfone. Commercially available polymers (for norbornene polymers, Arton (manufactured by JSR), Zeonore (manufactured by Nippon Zeon), etc.) may be used.

  In particular, when used as a protective film for a polarizing plate, a cellulose ester is preferable, and a lower fatty acid ester of cellulose is more preferable. Lower fatty acid means a fatty acid having 6 or less carbon atoms. The number of carbon atoms is preferably 2 (cellulose acetate), 3 (cellulose propionate) or 4 (cellulose butyrate). Mixed fatty acid esters such as cellulose acetate propionate and cellulose acetate butyrate may be used. Of the lower fatty acid esters of cellulose, cellulose acetate is most preferred. The acyl group substitution degree of the cellulose ester is preferably 2.50 to 3.00, more preferably 2.75 to 2.95, and most preferably 2.80 to 2.90.

  The viscosity average polymerization degree (DP) of the cellulose ester is preferably 250 or more, and more preferably 290 or more. In addition, the cellulose ester preferably has a narrow molecular weight distribution of Mm / Mn (Mm is a mass average molecular weight, Mn is a number average molecular weight) by gel permeation chromatography. The value of Mm / Mn is preferably 1.0 to 5.0, more preferably 1.3 to 3.0, and most preferably 1.4 to 2.0.

  In the cellulose ester, the hydroxyl groups at the 2-position, 3-position and 6-position of cellulose are not evenly substituted but the degree of substitution at the 6-position tends to be small. In the present invention, the 6-position substitution degree of the cellulose ester is preferably about the same as or higher than the 2-position and 3-position. The ratio of the 6-position substitution degree to the total of the 2-position, 3-position and 6-position substitution degrees is preferably 30 to 40%. The ratio of the 6-position substitution degree is preferably 31% or more, particularly preferably 32% or more. The substitution degree at the 6-position is preferably 0.88 or more. The 6-position of cellulose may be substituted with an acyl group having 3 or more carbon atoms (eg, propionyl, butyryl, valeroyl, benzoyl, acryloyl) in addition to acetyl. The degree of substitution at each position can be measured by NMR. Cellulose esters having a high degree of substitution at the 6-position are described in Synthesis Example 1 described in Paragraph Nos. 0043 to 0044, Synthesis Example 2 described in Paragraph Nos. 0048 to 0049, and Paragraph Nos. 0051 to 0052. It can synthesize | combine with reference to the synthesis example 3 of these.

  A plasticizer can be added to the cellulose ester film in order to improve mechanical properties or increase the drying speed. As the plasticizer, phosphoric acid ester or carboxylic acid ester is used. Examples of phosphate esters include triphenyl phosphate (TPP), biphenyl diphenyl phosphate, and tricresyl phosphate (TCP). Representative examples of the carboxylic acid ester include phthalic acid esters and citric acid esters. Examples of phthalic acid esters include dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), dioctyl phthalate (DOP), diphenyl phthalate (DPP) and diethyl hexyl phthalate (DEHP). Examples of citrate esters include triethyl O-acetylcitrate (OACTE) and tributyl O-acetylcitrate (OACTB). Examples of other carboxylic acid esters include butyl oleate, methylacetyl ricinoleate, dibutyl sebacate, and various trimellitic acid esters. Phthalate plasticizers (DMP, DEP, DBP, DOP, DPP, DEHP) are preferably used. DEP and DPP are particularly preferred. The addition amount of the plasticizer is preferably 0.1 to 25% by weight of the amount of cellulose ester, more preferably 1 to 20% by weight, and most preferably 3 to 15% by weight.

  A degradation inhibitor (eg, antioxidant, peroxide decomposer, radical inhibitor, metal deactivator, acid scavenger, amine) may be added to the cellulose ester film. The deterioration preventing agents are described in JP-A-3-199201, JP-A-51907073, JP-A-5-194789, JP-A-5-271471, and JP-A-6-107854. The addition amount of the deterioration preventing agent is preferably 0.01 to 1% by weight of the solution (dope) to be prepared, and more preferably 0.01 to 0.2% by weight. When the addition amount is less than 0.01% by weight, the effect of the deterioration preventing agent is hardly recognized. When the added amount exceeds 1% by weight, bleed-out (bleeding) of the deterioration preventing agent to the film surface may be observed. Examples of particularly preferred deterioration inhibitors include butylated hydroxytoluene (BHT) and tribenzylamine (TBA). Furthermore, a very small amount of dye may be added to prevent light piping. From the viewpoint of transmittance, it is preferable to adjust the type and amount so that the transmittance of light having a wavelength of 420 nm is 50% or more. The added amount of the dye is preferably 0.01 ppm to 1 ppm.

  In order to control the Re retardation value and the Rth retardation value, a retardation control agent can be added to the cellulose ester film. The retardation control agent is preferably used in the range of 0.01 to 20 parts by mass, more preferably 0.05 to 15 parts by mass, with respect to 100 parts by mass of the cellulose ester. Most preferably, it is used in the range of 1 to 10 parts by mass. Two or more retardation control agents may be used in combination. The retardation control agent is described in the pamphlets of International Publication No. WO01 / 88574 and International Publication No. WO00 / 2619, and Japanese Unexamined Patent Publication Nos. 2000-1111914 and 2000-275434.

  The cellulose ester film can be produced by a solvent cast method using a solution containing cellulose ester and other components as a dope. The dope is cast on a drum or band and the solvent is evaporated to form a film. The concentration of the dope before casting is preferably adjusted so that the solid content is 10 to 40% by weight. The solid content is more preferably 18 to 35% by weight. Two or more dopes can be cast. The surface of the drum or band is preferably finished in a mirror state. The casting and drying methods in the solvent casting method are described in U.S. Pat. No. 736892, JP-B Nos. 45-4554, 49-5614, JP-A-60-176834, No. 60-203430, and No. 62-115035.

  The dope is preferably cast on a drum or band having a surface temperature of 10 ° C. or less. After casting, it is preferable to dry it by applying air for 2 seconds or more. Then, the method can be employed in which the obtained film is peeled off from the drum or band and further dried with high-temperature air at different temperatures of 100 to 160 ° C. to evaporate the residual solvent (described in Japanese Patent Publication No. 5-17844). . According to this method, it is possible to shorten the time from casting to stripping. In order to carry out this method, it is necessary for the dope to gel at the surface temperature of the drum or band during casting. When casting a plurality of cellulose ester solutions, a solution is prepared by casting a solution containing cellulose ester from a plurality of casting openings provided at intervals in the traveling direction of the support, and laminating them. (Japanese Patent Laid-Open Nos. 61-158414, 1-122419, and 11-198285). A film can also be produced by casting a cellulose ester solution from two casting ports (Japanese Patent Publication Nos. 60-27562, 61-94724, 61-947245, 61-104413, No. 61-158413 and JP-A-6-134933). Employs a method of casting a cellulose ester film (described in JP-A-56-162617) by wrapping a flow of a high-viscosity cellulose ester solution with a low-viscosity cellulose ester solution and simultaneously extruding the high-viscosity and low-viscosity cellulose ester solutions. May be.

  The retardation of the cellulose ester film can be further adjusted by a stretching treatment. The draw ratio is preferably in the range of 3 to 100%. Tenter stretching is preferred. In order to control the slow axis with high accuracy, it is preferable to make the difference between the left and right tenter clip speeds and the separation timing as small as possible. The stretching process is described on page 37, line 8 to page 38, line 8 of WO 01/88574.

  The cellulose ester film can be subjected to a surface treatment. Examples of the surface treatment include corona discharge treatment, glow discharge treatment, flame treatment, acid treatment, alkali treatment, and ultraviolet irradiation treatment. From the viewpoint of maintaining the flatness of the film, the temperature of the cellulose ester film in the surface treatment is preferably Tg (glass transition temperature) or lower, specifically 150 ° C. or lower.

  The thickness of the cellulose ester film can be adjusted by lip flow rate and line speed, or stretching or compression when it is produced by film formation. Since the moisture permeability varies depending on the main material to be used, it is possible to adjust the thickness to a preferable moisture permeability range as a protective film for the polarizing plate. Moreover, the free volume of the said cellulose-ester film can be adjusted with drying temperature and time, when producing by film forming. Also in this case, since the moisture permeability varies depending on the main material used, it is possible to make the moisture permeability range preferable as a protective film by adjusting the free volume. The hydrophilicity / hydrophobicity of the cellulose ester film can be adjusted by an additive. Moisture permeability is increased by adding a hydrophilic additive in the free volume, and conversely, moisture permeability can be lowered by adding a hydrophobic additive. Thus, by adjusting the moisture permeability of the cellulose ester film by various methods, it is possible to obtain a range of moisture permeability preferable as a protective film for the polarizing plate, and the support of the optically anisotropic layer is protected for the polarizing plate. A polarizing plate that can also serve as a film and has an optical compensation capability can be manufactured at low cost with high productivity.

[Polarizer]
The polarizing plate used for the liquid crystal display device of the present invention comprises a polarizing film and a pair of protective films that sandwich the polarizing film. Examples of the polarizing film include an iodine polarizing film, a dye polarizing film using a dichroic dye, and a polyene polarizing film. The iodine polarizing film and the dye polarizing film are generally produced using a polyvinyl alcohol film. The kind of protective film is not particularly limited, and cellulose esters such as cellulose acetate, cellulose acetate butyrate, and cellulose propionate, polycarbonate, polyolefin, polystyrene, polyester, and the like can be used. The transparent protective film is usually supplied in a roll form, and it is preferable that the transparent protective film is continuously bonded to the long polarizing film so that the longitudinal directions thereof coincide. Here, the orientation axis (slow axis) of the protective film may be any direction. Further, the angle between the slow axis (alignment axis) of the protective film and the absorption axis (stretching axis) of the polarizing film is not particularly limited, and can be appropriately set according to the purpose of the polarizing plate.

The polarizing film and the protective film may be bonded together with an aqueous adhesive. The adhesive solvent in the water-based adhesive is dried by diffusing in the protective film. The higher the moisture permeability of the protective film, the faster the drying and the higher the productivity. However, if the protective film is too high, the moisture will enter the polarizing film due to the usage environment (high humidity) of the liquid crystal display device. The performance drops. The moisture permeability of the optical compensation sheet is determined by the thickness, free volume, hydrophilicity / hydrophobicity, etc. of the polymer film (and polymerizable liquid crystal compound). The moisture permeability of the protective film for the polarizing plate is preferably in the range of 100 to 1000 (g / m ² ) / 24 hrs, and more preferably in the range of 300 to 700 (g / m ² ) / 24 hrs.

  In the present invention, for the purpose of reducing the thickness, one of the protective films of the polarizing film may also serve as the support for the optically anisotropic layer, or the optically anisotropic layer itself. The optically anisotropic layer and the polarizing film are preferably subjected to a fixing treatment from the viewpoint of preventing displacement of the optical axis and preventing entry of foreign matters such as dust. An appropriate method such as an adhesive method through a transparent adhesive layer can be applied to the fixed lamination. There is no particular limitation on the type of the adhesive and the like, and from the viewpoint of preventing changes in the optical properties of the constituent members, those that do not require a high-temperature process during curing or drying are preferable, and a long-time curing process is preferable. And those that do not require drying time. From such a viewpoint, a hydrophilic polymer adhesive or a pressure-sensitive adhesive layer is preferably used.

  Appropriate functional layers such as a protective film for various purposes such as water resistance according to the above protective film, an antireflection layer and / or an antiglare treatment layer for the purpose of preventing surface reflection, etc. on one or both sides of the polarizing film You may use the polarizing plate which formed. The antireflection layer can be suitably formed, for example, as a light interference film such as a fluorine polymer coating layer or a multilayer metal vapor deposition film. The antiglare layer is also formed by an appropriate method that diffuses the surface reflected light, for example, by providing a fine uneven structure on the surface by an appropriate method such as a resin coating layer containing fine particles, embossing, sandblasting or etching. can do.

  Examples of the fine particles include inorganic materials such as silica, calcium oxide, alumina, titania, zirconia, tin oxide, indium oxide, cadmium oxide, and antimony oxide having an average particle diameter of 0.5 to 20 μm. One kind or two or more kinds of fine particles, cross-linked or non-cross-linked organic fine particles made of a suitable polymer such as polymethyl methacrylate and polyureta can be used. The above-mentioned adhesive layer or pressure-sensitive adhesive layer may contain such fine particles and exhibit light diffusibility.

  The optical properties and durability (storability in the short term and long term) of the polarizing plate comprising the protective film, the polarizing film and the transparent support relating to the present invention are commercially available super high contrast products (for example, manufactured by Sanritz Corporation). HLC2-5618 etc.) is preferable. Specifically, the visible light transmittance is 42.5% or more, and the degree of polarization √ {(Tp−Tc) / (Tp + Tc)} ≧ 0.9995 (where Tp is parallel transmittance and Tc is orthogonal transmittance) The rate of change in light transmittance before and after standing for 500 hours in an atmosphere of 60 ° C. and 90% RH for 500 hours and 80 ° C. for 500 hours in a dry atmosphere is 3% or less based on the absolute value. Is preferably 1% or less, and the rate of change in the degree of polarization is preferably 1% or less, more preferably 0.1% or less, based on the absolute value.

  The display mode of the liquid crystal display device used in the present invention is not particularly limited, but the VA mode is preferably used. Note that the liquid crystal display device used in the present invention is effective not only in the display mode but also in an aspect applied to the STN mode, the TN mode, and the OCB mode.

[VA mode liquid crystal cell]
In the present invention, the liquid crystal cell is preferably in a vertically aligned mode (VA mode). The VA mode liquid crystal cell is formed by sealing liquid crystal molecules having negative dielectric anisotropy between upper and lower substrates whose opposite surfaces are rubbed. For example, by using liquid crystal molecules having Δn = 0.0813 and Δε = −4.6, a director indicating the alignment direction of the liquid crystal molecules, that is, a liquid crystal cell having a so-called tilt angle of about 89 ° can be manufactured. At this time, the thickness d of the liquid crystal layer can be about 3.5 μm. The brightness at the time of white display changes depending on the magnitude of the product Δn · d of the thickness d (nm) of the liquid crystal layer and the refractive index anisotropy Δn. In order to obtain the maximum brightness, the thickness d of the liquid crystal layer is preferably in the range of 2 to 5 μm (2000 to 5000 nm), and Δn is in the range of 0.060 to 0.085.

  Transparent electrodes are formed inside the upper and lower substrates of the liquid crystal cell 35, but in a non-driving state in which no driving voltage is applied to the electrodes, the liquid crystal molecules in the liquid crystal layer are aligned substantially perpendicular to the substrate surface, and as a result The polarization state of light passing through the liquid crystal panel hardly changes. Since the absorption axis of the upper polarizing plate 37 of the liquid crystal cell and the absorption axis of the lower polarizing plate 36 are substantially orthogonal, light does not pass through the polarizing plate. In other words, in the VA mode liquid crystal display device, an ideal black display can be realized in the non-driven state. On the other hand, in the driving state, the liquid crystal molecules are inclined in a direction parallel to the substrate surface, and the light passing through the liquid crystal panel changes the polarization state by the inclined liquid crystal molecules and passes through the polarizing plate.

  Up to this point, since an electric field is applied between the upper and lower substrates, an example using a liquid crystal material having a negative dielectric anisotropy in which liquid crystal molecules respond perpendicularly to the electric field direction has been shown. In the case where the liquid crystal material is disposed on the substrate and an electric field is applied in a lateral direction parallel to the substrate surface, a liquid crystal material having a positive dielectric anisotropy can be used.

  The characteristics of the VA mode are high-speed response and high contrast. However, there is a problem that the contrast is high in the front but decreases in the oblique direction. Since the liquid crystal molecules are aligned perpendicular to the substrate surface during black display, when viewed from the front, there is almost no birefringence of the liquid crystal molecules, so the transmittance is low and high contrast can be obtained. However, when observed obliquely, birefringence occurs in the liquid crystalline molecules. Furthermore, the crossing angle of the upper and lower polarizing plate absorption axes is 90 ° perpendicular to the front, but is greater than 90 ° when viewed from an oblique direction. Due to these two factors, leakage light tends to occur in the oblique direction, and the contrast tends to decrease. In the present invention, in order to solve this problem, at least one optically anisotropic layer is provided on a transparent support having predetermined optical characteristics.

  In the VA mode, liquid crystal molecules are tilted during white display, but the birefringence of the liquid crystal molecules when viewed from an oblique direction is different between the tilt direction and the opposite direction, resulting in differences in luminance and color tone. . In order to solve this, the liquid crystal cell is preferably multi-domain. Multi-domain refers to a structure in which a plurality of regions having different alignment states are formed in one pixel. For example, in a multi-domain VA mode liquid crystal cell, a plurality of regions in which tilt angles of liquid crystal molecules are different from each other when an electric field is applied exist in one pixel. In a multi-domain VA mode liquid crystal cell, the tilt angle of liquid crystal molecules due to application of an electric field can be averaged for each pixel, whereby the viewing angle characteristics can be averaged. Dividing the orientation within one pixel can be achieved by providing a slit in the electrode, providing a protrusion, changing the direction of the electric field, or biasing the electric field density. In order to obtain a uniform viewing angle in all directions, the number of divisions may be increased. However, since the transmittance during white display is reduced, four divisions are preferable.

  In a VA mode liquid crystal display device, the addition of a chiral material generally used in a Twisted Nematic mode (TN mode) liquid crystal display device is rarely used to degrade the dynamic response characteristics. Sometimes added to reduce. At the boundary of the alignment division, the liquid crystal molecules are difficult to respond. For this reason, in normally black display, since black display is maintained, a reduction in luminance becomes a problem. Adding a chiral agent to the liquid crystal material contributes to reducing the boundary region.

  The present invention will be described more specifically with reference to the following examples. The materials, reagents, amounts and ratios of substances, operations, and the like shown in the following examples can be appropriately changed without departing from the gist of the present invention. Therefore, the scope of the present invention is not limited to the following specific examples.

(Preparation of transparent support S-1)
A commercial cellulose acetate film, Fujitac TD80UF (Fuji Photo Film Co., Ltd., Re = 3 nm, Rth = 50 nm) was used as the transparent support S-1.

(Preparation of transparent support S-2)
The following composition was put into a mixing tank and stirred while heating to dissolve each component to prepare a cellulose acetate solution.
───────────────────────────────────
Cellulose acetate solution composition (%) Inner layer Outer layer ───────────────────────────────────
Cellulose acetate with an acetylation degree of 60.9% 20.89 19.78
Triphenyl phosphate (plasticizer) 1.63 1.54
Biphenyl diphenyl phosphate (plasticizer) 0.815 0.770
Methylene chloride (first solvent) 61.22 62.12
Methanol (second solvent) 14.83 15.03
1-butanol (third solvent) 0.313 0.320
Silica (particle size 20 nm) 0.00 0.160
Retardation increasing agent S-2-1 0.302 0.280
──────────────────────────────────――

  The obtained inner layer dope and outer layer dope were cast on a drum cooled to 0 ° C. using a three-layer co-casting die. The film with a residual solvent amount of 70% by mass is peeled off from the drum, both ends are fixed with a pin tenter and dried at 80 ° C. while being conveyed with a draw ratio in the conveying direction of 110%, and the residual solvent amount is 10% by mass. Then, it was dried at 110 ° C. Thereafter, a cellulose acetate film (outer layer: 3 μm, inner layer: 74 μm, outer layer: 3 μm) having a residual solvent of 0.3% by mass produced by drying at 140 ° C. for 30 minutes was used as the transparent support S-2. The optical properties of the obtained film were Re = 8 nm and Rth = 82 nm.

(Preparation of transparent support S-3)
The following composition was put into a mixing tank and stirred while heating to dissolve each component to prepare a cellulose acylate solution.
──────────────────────────────────――
Cellulose acylate solution composition (%)
──────────────────────────────────――
Cellulose acylate (substitution degree of acetate group 1.2, butyryl group 1.3)
24.0
Mixed solvent (Table 75.0 below)
Retardation increasing agent S-3-1 0.70
2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-tert-butylanilino) -1,3,5-triazine (UV agent a) 0.12
2 (2′-hydroxy-3 ′, 5′-di-tert-butylphenyl) -5-chlorobenzotriazole (UV agent b) 0.05
2 (2′-hydroxy-3 ′, 5′-di-tert-amylphenyl) -5-chlorobenzotriazole (UV agent c) 0.02
Silica (972, manufactured by Nippon Aerosil Co., Ltd.) 0.06
Citric acid ethyl ester (1: 1 mixture of monoester and diester) 0.05
──────────────────────────────────――

──────────────────────────────────――
Mixed solvent composition (%)
──────────────────────────────────――
Methyl acetate 80.0
Acetone 5.0
Methanol 7.0
Ethanol 5.0
Butanol 3.0
──────────────────────────────────――

  Then, it filtered with the filter paper (Toyo Filter Paper Co., Ltd. product # 63) with an absolute filtration accuracy of 0.01 mm, and further filtered with the filter paper (FH025 made by Paul Co., Ltd.) with an absolute filtration accuracy of 2.5 μm. The above-mentioned dope was heated to 35 ° C., and casted through a Giesser onto a mirror surface stainless steel drum having a diameter of 3 m set at −15 ° C. The Gieseer used was similar to that described in Japanese Patent Application Laid-Open No. 11-314233. The casting speed was 100 m / min and the casting width was 250 cm. After the residual solvent was peeled off at 200% by mass, the film was dried at 130 ° C. and wound up when the residual solvent became 1% by mass or less to prepare a cellulose acylate film. The obtained film was trimmed at both ends by 3 cm, and then a knurling having a height of 100 μm was imparted to a portion 2 to 10 mm from both ends, and wound into a 3000 m roll. The biaxially stretched film was used as a transparent support S-3 (Re = 10 nm, Rth = 40 nm).

(Preparation of coating liquid AL-1 for alignment layer)
The following composition was prepared, filtered through a polypropylene filter having a pore size of 30 μm, and used as an alignment layer coating liquid AL-1.
──────────────────────────────────――
Coating liquid composition for alignment layer (%)
──────────────────────────────────――
Modified polyvinyl alcohol AL-1-1 4.01
Water 72.89
Methanol 22.83
Glutaraldehyde (crosslinking agent) 0.20
Citric acid 0.008
Citric acid monoethyl ester 0.029
Citric acid diethyl ester 0.027
Citric acid triethyl ester 0.006
──────────────────────────────────――

(Preparation of coating liquid LC-1 for optically anisotropic layer)
After preparing the following composition, it filtered with the polypropylene filter with the hole diameter of 0.2 micrometer, and used as coating liquid LC-1 for optical anisotropic layers.
──────────────────────────────────――
Coating composition for optically anisotropic layer (%)
──────────────────────────────────――
Rod-shaped liquid crystal (LC-1-1) 6.67
Rod-shaped liquid crystal (LC-1-2) 2.60
Chiral agent (LC-1-3) 21.07
Chiral agent (LC-1-4) 1.67
Chain transfer agent (LC-1-5) 0.67
Photopolymerization initiator (LC-1-6) 0.67
Methyl ethyl ketone 66.65
──────────────────────────────────――

ＬＣ−１−１：
Ａｎｇｅｗ． Ｍａｋｒｏｍｏｌ．Ｃｈｅｍ．誌、第１８３巻、４５頁（１９９０年）に記載の方法に準じて合成した。
ＬＣ−１−２：
ＥＰ１１７４４１１Ｂ１号に記載の方法により合成した４−（６−アクリロイルオキシヘキシルオキシ）安息香酸と、４−プロピルシクロヘキシルフェノール（関東化学製）を縮合して合成した。
ＬＣ−１−３：
ＥＰ１１７４４１１Ｂ１号に記載の方法により合成した４−（６−アクリロイルオキシヘキシルオキシ）安息香酸と、ＷＯ／２００１０４０１５４Ａ１号に記載の方法により合成した４−ヒドロキシ−４‘−（２−メチルブチル）ビフェニルを縮合して合成した。
ＬＣ−１−４：
ＥＰ１３８９１９９Ａ１に記載の方法により合成した。
ＬＣ−１−５：
ヒドロキシプロピルアクリレート（アルドリッチ社製）をメシル化した後、４−プロピルシクロヘキシルフェノール（関東化学製）と反応させ、次に硫化水素を付加して合成した。
ＬＣ−１−６：
４−プロピルシクロヘキシルフェノール（関東化学製）をトリフレート化した後、フェニルボロン酸による鈴木カップリング反応でビフェニル体とした。更に、イソ酪酸クロライドと塩化アルミでビフェニルの４’位をアシル化した後、カルボニルのα位の炭素を臭素によってブロム化、次いでアルカリにより水酸基とすることで合成した。

LC-1-1:
Angew. Makromol. Chem. It was synthesized according to the method described in Journal, Vol. 183, p. 45 (1990).
LC-1-2:
It was synthesized by condensing 4- (6-acryloyloxyhexyloxy) benzoic acid synthesized by the method described in EP1174411B1 and 4-propylcyclohexylphenol (manufactured by Kanto Chemical).
LC-1-3:
4- (6-acryloyloxyhexyloxy) benzoic acid synthesized by the method described in EP 1174411B1 and 4-hydroxy-4 ′-(2-methylbutyl) biphenyl synthesized by the method described in WO / 2001040154A1 are condensed. And synthesized.
LC-1-4:
It was synthesized by the method described in EP1389199A1.
LC-1-5:
Hydroxypropyl acrylate (manufactured by Aldrich) was mesylated, reacted with 4-propylcyclohexylphenol (manufactured by Kanto Chemical), and then hydrogen sulfide was added to synthesize.
LC-1-6:
4-Propylcyclohexylphenol (manufactured by Kanto Chemical Co., Ltd.) was triflated to give a biphenyl compound by Suzuki coupling reaction with phenylboronic acid. Furthermore, after acylating the 4′-position of biphenyl with isobutyric chloride and aluminum chloride, the carbon at the α-position of the carbonyl was brominated with bromine and then converted into a hydroxyl group with an alkali.

(Preparation of coating liquid LC-2 for optically anisotropic layer)
After the following composition was prepared, it was filtered through a polypropylene filter having a pore size of 0.2 μm and used as a coating liquid LC-2 for an optically anisotropic layer.
──────────────────────────────────――
Coating composition for optically anisotropic layer (%)
──────────────────────────────────――
Discotic liquid crystal (LC-2-1) 19.2
Additive (LC-2-2) 0.2
Photopolymerization initiator (LC-2-3) 0.6
Methyl ethyl ketone 80.0
──────────────────────────────────――

(Single-side saponification treatment of cellulose ester film)
The cellulose ester film was passed through a dielectric heating roll having a temperature of 60 ° C. and the film surface temperature was raised to 40 ° C., and then an alkali solution having the composition shown below was applied at 14 ml / m ² using a bar coater. Then, after retaining for 10 seconds under a steam far infrared heater (manufactured by Noritake Co., Ltd.) heated to 110 ° C., 3 ml / m ^{2 of} pure water was applied using the same bar coater. The film temperature at this time was 40 degreeC. Next, washing with a fountain coater and draining with an air knife were repeated three times, and then the sample was retained in a drying zone at 70 ° C. for 2 seconds and dried.

──────────────────────────────────――
Alkaline solution composition (%)
──────────────────────────────────――
Potassium hydroxide 4.7
Water 14.7
Isopropanol 64.8
Propylene glycol 14.8
Surfactant (SF-1) 1.0
──────────────────────────────────――

[Example 1]
One side of the transparent support S-1 was saponified using the above-mentioned one-side saponification method, and then the coating liquid AL-1 for alignment layer was applied thereon with a # 14 wire bar coater, An alignment layer having a thickness of 1.0 μm was formed by drying with warm air for 60 seconds and further with warm air at 90 ° C. for 150 seconds. Subsequently, the formed alignment layer was continuously rubbed with respect to the slow axis direction of the transparent support, and then 0.3% of the amphiphilic compound (I-1) was applied to the optically anisotropic layer coating liquid LC-. The mixed liquid crystal composition prepared by adding to No. 1 was applied to the rubbing treated surface with a # 3 wire bar coater and heat-dried at 60 ° C. for 1 minute to form an optically anisotropic layer having a uniform liquid crystal phase. Further, immediately after aging, the transmission axis of the polarizing plate is set to the fast axis direction of the transparent support using POLUV-1 in a nitrogen atmosphere with an oxygen concentration of 0.3% or less with respect to the optically anisotropic layer. The optical compensation sheet of Example 1 was produced by irradiation with polarized UV (illuminance 200 mW / cm ² , irradiation amount 200 mJ / cm ² ). The optically anisotropic layer showed no liquid crystal phase even when heated after fixing. The thickness of the optically anisotropic layer was 1.3 μm. The following evaluation was performed on the obtained optical compensation sheet.

(Close contact)
The presence or absence of peeling was visually observed by a cross-cut method, and the following three-stage evaluation was performed.
◯: No peeling was observed
Δ: 10% or more peeling was observed
X: 50% peeled off

(Phase difference measurement)
Retardation Re (40) and Re (−40) when a sample is tilted ± 40 degrees with KOBRA 21ADH (manufactured by Oji Scientific Instruments Co., Ltd.) and front retardation Re at 589 nm and the slow axis as the rotation axis. It was measured.

[Example 2]
An optical compensation sheet was produced in the same manner as in Example 1 except that the amphiphilic compound (I-1) was replaced with the amphiphilic compound (I-6).
[Example 3]
One side of the transparent support S-1 was saponified using the above-mentioned one-side saponification method, and then the coating liquid AL-1 for alignment layer was applied thereon with a # 14 wire bar coater, An alignment layer having a thickness of 1.0 μm was formed by drying with warm air for 60 seconds and further with warm air at 90 ° C. for 150 seconds. Subsequently, the formed alignment layer was continuously rubbed with respect to the slow axis direction of the transparent support, and then 0.3% of the amphiphilic compound (I-1) was applied to the optically anisotropic layer coating liquid LC-. The mixed liquid crystal composition prepared by adding to No. 2 was applied to the rubbing-treated surface with a # 3 wire bar coater and heat-dried at 125 ° C. for 1 minute to form an optically anisotropic layer having a uniform liquid crystal phase. Further, immediately after aging, the transmission axis of the polarizing plate is set to the fast axis direction of the transparent support using POLUV-1 in a nitrogen atmosphere with an oxygen concentration of 0.3% or less with respect to the optically anisotropic layer. The optical compensation sheet of Example 1 was produced by irradiation with polarized UV (illuminance 200 mW / cm ² , irradiation amount 200 mJ / cm ² ). The optically anisotropic layer showed no liquid crystal phase even when heated after fixing. The thickness of the optically anisotropic layer was 1.3 μm. The following evaluation was performed on the obtained optical compensation sheet.
[Example 4]
An optical compensation sheet was produced in the same manner as in Example 1 except that the support S-1 was replaced with the support S-2.
[Example 5]
An optical compensation sheet was produced in the same manner as in Example 3 except that the support S-1 was replaced with the support S-3 and the optically anisotropic layer coating liquid LC-1 was replaced with LC-2.

[Comparative Example 1]
One side of the transparent support S-1 was saponified using the above-mentioned one-side saponification method, and then the coating liquid AL-1 for alignment layer was applied thereon with a # 14 wire bar coater, An alignment layer having a thickness of 1.0 μm was formed by drying with warm air for 60 seconds and further with warm air at 90 ° C. for 150 seconds. Subsequently, the formed alignment layer was continuously rubbed with respect to the slow axis direction of the transparent support, and then the optical anisotropic layer coating liquid LC-1 was applied thereon with a # 3 wire bar coater, An optically anisotropic layer having a uniform liquid crystal phase was formed by heating and drying at 60 ° C. for 1 minute. Further, immediately after aging, the transmission axis of the polarizing plate is made to be in the fast axis direction of the transparent support using POLUV-1 in a nitrogen atmosphere with an oxygen concentration of 0.3% or less with respect to the optically anisotropic layer. Then, the optical compensation sheet of Example 1 was produced by irradiating with polarized UV (illuminance 200 mW / cm 2, irradiation amount 200 mJ / cm ² ). The optically anisotropic layer showed no liquid crystal phase even when heated after fixing. The thickness of the optically anisotropic layer was 1.3 μm. The obtained optical compensation sheet was evaluated in the same manner as in Example 1.
[Comparative Example 2]
An optical compensation sheet was prepared in the same manner as in Comparative Example 1 except that the optical anisotropic layer coating liquid LC-1 was replaced with the optical anisotropic layer coating liquid LC-2.

  The adhesion evaluation results of Examples 1 to 5 and Comparative Examples 1 and 2 are shown in Table 1, and the phase difference measurement results of the optically anisotropic layers of Examples 1 to 5 and Comparative Examples 1 and 2 are shown in Table 2.

(Preparation of polarizing plate with optical compensation sheet)
The optical compensation sheets of Examples 1 to 3 and 5 of the present invention and Comparative Example 1 and the commercially available Fujitac TD80UF (Fuji Photo Film Co., Ltd., Re = 3 nm, Rth = 50 nm) were mixed with 1.5 mol / L of water. It was immersed in an aqueous sodium oxide solution at 55 ° C. for 2 minutes. Subsequently, it was washed in a water bath at room temperature and neutralized at 30 ° C. with 0.05 mol / L sulfuric acid. This was washed again in a room temperature water bath and further dried with hot air at 100 ° C. Thereafter, washing with water and neutralization treatment were performed, and the two saponified films were attached to both surfaces of the polarizing film with a roll-to-roll using a polyvinyl alcohol adhesive as a protective film for the polarizing plate. A body-type polarizing plate was produced. All the examples of the present invention were excellent in productivity, and the optically anisotropic layer showed a good surface shape. The comparative example not only has insufficient adhesion, but also caused problems such as a decrease in productivity due to the saponification treatment on one side before the alignment layer coating and contamination of the saponification bath during processing of the polarizing plate. .

[Example 6]
(Production of VA-LCD liquid crystal display device)
The upper and lower polarizing plates of a commercially available VA-LCD (SyncMaster 173P, manufactured by Samsung Electronics Co., Ltd.) are peeled off, the normal polarizing plate is formed on the upper side, and the polarizing plate with an optical compensation sheet of the present invention prepared in Example 1 is formed on the lower side. Were bonded with an adhesive so that the optically anisotropic layer became the glass surface of the liquid crystal cell substrate, thereby producing the liquid crystal display device of the present invention. A schematic cross-sectional view of the manufactured liquid crystal display device is shown in FIG. 4 together with the angular relationship of the optical axes of the respective layers. In FIG. 4, 41 is a polarizing layer, 42 is a transparent support, 43 is an alignment layer, 44 is an optically anisotropic layer (41 to 44 constitute the optical compensation sheet of the present invention), 45 is a polarizing plate protective film, 46 is a glass substrate for a liquid crystal cell, 47 is a liquid crystal cell, and 48 is an adhesive layer. Further, the arrow in the polarizing layer 41 indicates the direction of the absorption axis, the arrow in the optically anisotropic layer 44 or its support 44 and the protective film 45 indicates the direction of the slow axis, and the circle indicates the direction of the arrow relative to the paper surface. Indicates the line direction.

(Evaluation of VA-LCD liquid crystal display device)
The viewing angle characteristics of the manufactured liquid crystal display device were measured with a viewing angle measuring device (EZ Contrast 160D, manufactured by ELDIM). Furthermore, it evaluated also visually about 45 degree | times diagonally especially. FIG. 5 shows the contrast characteristics by EZ Contrast of Example 6 and Table 3 shows the visual evaluation results.

It is the schematic which shows an example of the liquid crystal display device of this invention. It is a schematic sectional drawing of the example of the polarizing plate of this invention. It is a schematic sectional drawing of an example of the liquid crystal display device of this invention. It is the schematic sectional drawing which showed the layer structure of the liquid crystal display device produced in Example 6 with the direction of the optical axis in a layer. FIG. 11 is a graph showing contrast characteristics of the liquid crystal display device manufactured in Example 6.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Transparent support 12 Optically anisotropic layer 13 which consists of liquid crystalline compound Orientation layer 21 Polarizing layers 22, 23 Protective film 24 Functional layer 31, such as (lambda) / 4 board, anti-reflective film, Cold cathode tube 32 Reflective sheet 33 Light guide plate 34 Light control film 35 such as brightness enhancement film and diffusion film 35 Liquid crystal cell 36 Lower polarizing plate 37 Upper polarizing plate 41 Polarizing layer 42 Transparent support 43 Orientation layer 44 Optical anisotropic layer 45 Polarizing plate protective film 46 Glass substrate for liquid crystal cell 47 Liquid crystal cell 48 Adhesive 51 Uniaxially stretched optical compensation sheet

Claims (14)

A transparent support, an alignment layer formed by applying and drying a solution having a solvent composition of 20% or more of water on the transparent support, and at least one polymerizable group on the surface of the alignment layer An optical compensation sheet having an optically anisotropic layer formed of a composition containing at least one liquid crystalline compound and at least one amphiphilic compound having a polymerizable group, the front letter of the optically anisotropic layer Letter measured with light having a wavelength of λ nm incident from a direction tilted by + 40 ° with respect to the normal direction of the optical compensation sheet with the in-plane slow axis as the tilt axis (rotation axis). The retardation value measured by injecting light having a wavelength of λ nm from the direction inclined by −40 ° with respect to the normal direction of the optical compensation sheet with the in-plane slow axis as the tilt axis (rotation axis) is substantially Target Equal optical compensation sheet. The at least one liquid crystal compound is a rod-like liquid crystal compound having at least one polymerizable group, and the optically anisotropic layer is a layer formed by polymerizing the polymerizable group. The optical compensation sheet according to 1. The at least one liquid crystal compound is a discotic liquid crystal compound having at least one polymerizable group, and the optically anisotropic layer is a layer formed by polymerization reaction of the polymerizable group. 2. The optical compensation sheet according to 1. At least one of the liquid crystalline compounds is a rod-like liquid crystalline compound having at least one polymerizable group, the composition further contains a chiral agent, and the optically anisotropic layer causes the polymerizable group to undergo a polymerization reaction. The optical compensation sheet according to claim 1, wherein the optical compensation sheet is a layer formed. The optical compensation sheet according to any one of claims 1 to 4, wherein the amphiphilic compound having at least one polymerizable group is a compound represented by the following general formula (I).
Formula (I)

(In the formula, Z represents a polymerizable group, X ¹ represents a linking group, and Q represents a hydrophilic group). 6. The optical compensation sheet according to claim 5, wherein the amphiphilic compound having at least one polymerizable group is a compound represented by the following general formula (II).

(In the formula, Z represents a polymerizable group, X ¹ represents a linking group, and R ¹ and R ² each independently represents a hydrogen atom, or a substituted or unsubstituted alkyl group, alkenyl group, alkynyl group or aryl group) . The optical compensation sheet according to claim 5 or 6, wherein Z is a group represented by the following general formula (III), or a group having an oxirane moiety or an oxetane moiety.

(Wherein R ³ represents a hydrogen atom or a methyl group, and L ¹ represents a single bond or a divalent linking group). The optical compensation sheet according to any one of claims 5 to 7 X ¹ is arylene. The optical compensation sheet according to claim 1, wherein the alignment layer is made of a polymer selected from a polyvinyl alcohol derivative having a polymerizable group in a side chain, a poly (meth) acrylate derivative, and a polysaccharide. . A step of applying and drying a solution having a solvent composition of 20% or more of water on a transparent support to form an alignment layer; and a rod-like liquid crystalline compound having at least one polymerizable group on the surface of the alignment layer; Applying a liquid crystal composition containing at least one kind of a chiral agent and an amphiphilic compound having at least one polymerizable group, and cholesterically aligning the molecules of the rod-like liquid crystalline compound with an average tilt angle of less than 5 °; The method for producing an optical compensation sheet according to claim 1, wherein the step of irradiating polarized light and polymerizing molecules of the rod-like liquid crystal compound to form an optically anisotropic layer is performed in this order. A step of applying a solution having a solvent composition of 20% or more of water on a transparent support and drying to form an alignment layer; and a discotic liquid crystalline compound having at least one polymerizable group on the surface of the alignment layer Applying a liquid crystal composition containing at least one chiral agent and at least one amphiphilic compound having at least one polymerizable group, and orienting the molecules of the discotic liquid crystalline compound at an average tilt angle of less than 5 °. The method for producing an optical compensation sheet according to claim 1, wherein the step of irradiating polarized light and polymerizing molecules of the discotic liquid crystal compound to form an optically anisotropic layer is performed in this order. The polarizing plate which has at least 1 sheet of the optical compensation sheet of any one of Claims 1-9, and a polarizer. A liquid crystal display device comprising the optical compensation sheet according to claim 1 or the polarizing plate according to claim 12. The liquid crystal display device according to claim 13, which is in a VA mode.

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