JP2006258854A - Optical anisotropic film, its manufacturing method, and liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical anisotropic film contributed to improvement of a field angle of a liquid crystal display. <P>SOLUTION: The optical anisotropic film is formed of a composition containing at least one kind of liquid crystal compounds exhibiting a smectic phase on an alignment layer and an additive having chain transfer capability and is fixed in a state where the liquid crystal compound is aligned. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a liquid crystal display device, and more particularly to an in-plane switching mode liquid crystal display device that performs display by applying a horizontal electric field to liquid crystal molecules aligned in a horizontal direction. The present invention also relates to an optically anisotropic film that contributes to improving the viewing angle characteristics of a liquid crystal display device, particularly an IPS mode liquid crystal display device.

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

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

As one means for improving the color tone and the viewing angle of black display, the arrangement of an optical compensation material having birefringence characteristics between the liquid crystal layer and the polarizing plate is also studied in the IPS mode. For example, by arranging a birefringent medium having an optical axis orthogonal to each other to compensate for the increase / decrease in retardation of the liquid crystal layer during tilting, a white display or a halftone display is diagonally arranged between the substrate and the polarizing plate. It is disclosed that coloring can be improved when viewing directly from (see Patent Document 1).
In addition, a method using an optical compensation film made of a styrenic polymer having a negative intrinsic birefringence or a discotic liquid crystalline compound (see Patent Documents 2, 3, and 4), or an optical axis as an optical compensation film with positive birefringence. Is a method of combining a film in the plane of the film with a film having a positive birefringence and an optical axis in the normal direction of the film (see Patent Document 5), biaxial optical compensation with a retardation of 1/2 wavelength A method using a sheet (see Patent Document 6), a method using a film having a negative retardation as a protective film of a polarizing plate, and providing an optical compensation layer having a positive retardation on this surface (see Patent Document 7) Proposed.
However, many of the previously proposed methods cancel out the birefringence anisotropy of the liquid crystal in the liquid crystal cell to improve the viewing angle. There is a problem that light leakage based on a deviation from an orthogonal angle cannot be sufficiently solved. Even in a system that can compensate for this light leakage, it is very difficult to completely optically compensate the liquid crystal cell without any problem. Furthermore, in the optical compensation sheet for IPS mode liquid crystal cell that performs optical compensation with the stretched birefringent polymer film, it is necessary to use a plurality of films. As a result, the thickness of the optical compensation sheet increases, and the display device becomes thinner It is disadvantageous. Moreover, since an adhesive layer is used for lamination | stacking of a stretched film, the adhesive layer contracted by the temperature / humidity change, and defects, such as peeling and a curvature between films, may generate | occur | produce.

  In addition, regarding a technique for fixing a liquid crystal material vertically in a smectic phase, Patent Document 10 requires a long time for alignment because the polymer liquid crystal material is vertically aligned. Further, Patent Documents 8 and 9 are not suitable for manufacturing on an industrial level, such as requiring a special alignment treatment for smectic phase alignment, or producing a retardation region on a glass substrate. The present inventor examined immobilization in a smectic phase according to Patent Document 9, but there was no problem before immobilization, but bright spots were generated at the immobilization stage, haze was increased, etc. The problem also occurred. No satisfactory manufacturing method was found on an industrial level

Japanese Patent Laid-Open No. 9-80424 Japanese Patent Laid-Open No. 10-54982 JP-A-11-202323 Japanese Patent Laid-Open No. 9-292522 JP 11-133408 A JP-A-11-305217 JP-A-10-307291 Special Table 2000-514202 Japanese Patent Laid-Open No. 10-319408 JP-A-6-331826

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an IPS liquid crystal display device with a simple configuration and not only display quality but also a viewing angle that is remarkably improved. The present invention also provides an optically anisotropic film that can be easily formed from a composition containing a liquid crystal compound, which contributes to an improvement in the viewing angle of a liquid crystal display device, in particular, an IPS liquid crystal display device, and the optical anisotropy. It is an object of the present invention to provide a method capable of stably producing a conductive film.

The object of the present invention is achieved by the following optically anisotropic films (1) to (4), the method for producing optically anisotropic films (5) below, and the liquid crystal display devices (6) to (11). It was.
(1) It is formed from a composition containing at least one liquid crystalline compound that exhibits a smectic phase on the alignment film and an additive having chain transfer ability, and the liquid crystalline compound is fixed in an aligned state. Optical anisotropic film.
(2) at least one additive that promotes vertical alignment of the liquid crystalline compound at the air interface and / or an additive that promotes vertical alignment of the liquid crystalline compound at the alignment film interface. The optically anisotropic film according to (1), which contains at least one kind and is fixed in a state where the liquid crystalline compound is vertically aligned.
(3) The optically anisotropic film according to (1) or (2), wherein the alignment film is a polyvinyl alcohol polymer.
(4) The optically anisotropic film according to any one of (1) to (3), wherein the composition contains at least one additive that promotes vertical alignment of the liquid crystal compound at the alignment film interface.
(5) At least one liquid crystalline compound exhibiting a smectic phase, at least one additive that promotes vertical alignment of the liquid crystalline compound at the air interface and / or vertical alignment of the liquid crystalline compound at the alignment film interface A composition containing at least one additive that promotes the coating is applied on the alignment film, heat-treated at a temperature equal to or higher than the transition temperature of the liquid crystal phase or isotropic phase of the liquid crystalline compound, and then cooled and fixed. A method for producing an optically anisotropic film.
(6) The method according to (5), wherein the liquid crystalline compound is cooled to the smectic phase and fixed after the heat treatment.
(7) A liquid crystal cell including at least a first polarizing film, a first retardation region, a second retardation region, and a liquid crystal layer sandwiched between a pair of substrates, wherein the liquid crystal molecules are the pair of substrates during black display. A liquid crystal display device oriented substantially parallel to the surface of
The retardation Re (λ) at the wavelength λ nm of the first retardation region is 20 nm to 150 nm, and the in-plane refractive indexes nx and ny (nx> ny) and the refractive index nz in the thickness direction are used to obtain Nz = The value Nz of the first phase difference region defined by (nx−nz) / (nx−ny) is 1.5 to 7,
The in-plane refractive indexes nx and ny of the second retardation region are substantially equal, nx <nz, and the retardation Rth (λ) in the thickness direction at the wavelength λnm of the second retardation region is −80 nm to −400 nm. And the second retardation region includes the optically anisotropic film according to any one of claims 1 to 4, and the transmission axis of the first polarizing film is a slow axis direction of liquid crystal molecules during black display. Liquid crystal display device that is parallel to.
(8) The first polarizing film, the first retardation region, the second retardation region, and the liquid crystal cell are arranged in this order, and the slow axis of the first retardation region is the first retardation layer. (7) The liquid crystal display device which is substantially parallel to the transmission axis of the polarizing film.
(9) The first polarizing film, the second retardation region, the first retardation region, and the liquid crystal cell are arranged in this order, and the slow axis of the first retardation region is the first polarizing film. The liquid crystal display device according to (7), which is substantially perpendicular to the transmission axis.
(10) It further has a second polarizing film having a transmission axis orthogonal to the transmission axis of the first polarizing film, and the first and second polarizing films are the first retardation region and the second retardation region. And the liquid crystal display device according to any one of (7) to (9), wherein the liquid crystal cell is interposed therebetween.
(11) having a pair of protective films arranged with the first polarizing film and / or the second polarizing film interposed therebetween, and the retardation in the thickness direction of the protective film closer to the liquid crystal layer of the pair of protective films The liquid crystal display device according to any one of (7) to (10), wherein Rth is 40 nm or less.
(12) It has a pair of protective films arranged with the first polarizing film and / or the second polarizing film in between, and the protective film on the side close to the liquid crystal layer of the pair of protective films is a cellulose acylate film or The liquid crystal display device according to any one of (7) to (11), which is a norbornene film.

The present invention includes at least a first polarizing film, a first retardation region, a second retardation region, and a liquid crystal cell in which a liquid crystal layer made of a liquid crystal material is sandwiched between a pair of substrates. A liquid crystal display device in which liquid crystal molecules of a liquid crystal material are aligned substantially parallel to the surfaces of the pair of substrates, wherein the retardation Re (λ) of the first retardation region is 20 nm to 150 nm (λ is Measurement wavelength), the in-plane refractive index nx and ny (nx> ny), and the refractive index nz value in the thickness direction are defined as Nz = (nx−nz) / (nx−ny). The value Nz1 of the one retardation region is 1.5 to 7, the in-plane refractive indexes nx and ny are substantially equal, nx <nz, and the thickness direction of the second retardation region The retardation Rth (λ) of -80 nm to -400 nm, When the transmission axis of the first polarizing film is parallel to the slow axis direction of the liquid crystal molecules at the time of black display, two sheets are seen when viewed from an oblique azimuth angle direction without changing any characteristics in the front direction. The reduction in contrast caused by the shift of the absorption axis of the polarizing plate from 90 degrees, particularly the decrease in contrast from an oblique direction of 45 degrees, is improved. The contrast can be further improved by setting the Rth of the protective film of the polarizing film to 40 nm or less.
In addition, according to the present invention, an IPS mode liquid crystal display that can be easily produced without using a special vertical alignment film by using a composition containing an additive having chain transfer ability together with a liquid crystalline compound. An optically anisotropic film that contributes to the improvement of the viewing angle characteristics of the device can be provided.

BEST MODE FOR CARRYING OUT THE INVENTION

  Hereinafter, an embodiment of the liquid crystal display device of the present invention and its constituent members will be described in order. In the present specification, a numerical range represented by using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.

In the present specification, Re (λ) and Rth (λ) respectively represent in-plane retardation and retardation in the thickness direction at a 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 light having a wavelength of λ nm from the direction inclined by + 40 ° with respect to the normal direction of the film, with Re (λ) and the in-plane slow axis (determined by KOBRA 21ADH) as the tilt axis (rotation axis). And a retardation value measured by injecting light having a wavelength of λ nm from a direction tilted by −40 ° with respect to the normal direction of the film with the in-plane slow axis as the tilt axis (rotation axis). KOBRA 21ADH is calculated based on the retardation values measured in three directions in total. As the wavelength λ, a value in the range of 450 to 750 nm is usually used. In the present application, a value of 589 nm is used. Here, as the assumed value of the average refractive index, values in the polymer handbook (John Wiley & Sons, Inc.) and catalogs of various optical films can be used. Those whose average refractive index is not known can be measured with an Abbe refractometer. Examples of the average refractive index values of main optical films are given below:
Cellulose acylate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49), and polystyrene (1.59).
The KOBRA 21ADH calculates nx, ny, and nz by inputting the assumed value of the average refractive index and the film thickness. Nz = (nx−nz) / (nx−ny) is further calculated from the calculated nx, ny, and nz.

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

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

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram showing an example of a pixel region of the liquid crystal display device of the present invention. 2 and 3 are schematic views of an embodiment of the liquid crystal display device of the present invention.
[Liquid Crystal Display]
The liquid crystal display device shown in FIG. 2 includes polarizing films 8 and 20, a first retardation region 10, a second retardation region 12, substrates 13 and 17, and a liquid crystal layer 15 sandwiched between the substrates. . Polarizing films 8 and 20 are sandwiched between protective films 7a and 7b and 19a and 19b, respectively.

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

  FIG. 1 schematically shows the alignment of liquid crystal molecules in one pixel region of the liquid crystal layer 15. FIG. 1 shows the alignment of liquid crystal molecules in a very small area corresponding to one pixel of the liquid crystal layer 15 in the rubbing direction 4 of the alignment film formed on the inner surfaces of the substrates 13 and 17 and the substrates 13 and 17. It is the schematic diagram shown with the electrodes 2 and 3 which can apply a voltage to the liquid crystal molecule formed in the inner surface. When active driving is performed using a nematic liquid crystal having positive dielectric anisotropy as a field effect liquid crystal, the liquid crystal molecule alignment directions in a no voltage application state or a low application state are 5a and 5b. A display is obtained. When applied between the electrodes 2 and 3, the liquid crystal molecules change their alignment direction in the directions of 6 a and 6 b in accordance with the voltage. Usually, bright display is performed in this state.

In FIG. 2 again, the transmission axis 9 of the polarizing film 8 and the transmission axis 21 of the polarizing film 20 are arranged orthogonally. The slow axis 11 of the first retardation region 10 is parallel to the transmission axis 9 of the polarizing film 8 and the slow axis direction 16 of the liquid crystal molecules in the liquid crystal layer 15 during black display.
In the liquid crystal display device shown in FIG. 2, the configuration in which the polarizing film 8 is sandwiched between the two protective films 7a and 7b is shown, but the protective film 7b may be omitted. When there is no protective film 7b, it is preferable that a part or all of the first retardation region 10 has a characteristic that can also function as the protective film 7b of the polarizing film. Further, although the polarizing film 20 is also sandwiched between the two protective films 19a and 19b, the protective film 19a on the side close to the liquid crystal layer 15 may be omitted. In the aspect of FIG. 2, the first retardation region and the second retardation region may be disposed between the liquid crystal cell and the viewing-side polarizing film with reference to the position of the liquid crystal cell. You may arrange | position between the liquid crystal cell and the polarizing film of the back side. In this embodiment, in any configuration, the second retardation region is disposed closer to the liquid crystal cell.

  Another embodiment of the present invention is shown in FIG. 3, the same members as those in FIG. 2 are denoted by the same reference numerals, and detailed description thereof is omitted. In the liquid crystal display device of FIG. 3, the second retardation region 12 is disposed between the polarizing film 8 and the first retardation region 10. In the liquid crystal display device of FIG. 3, the protective film 7b may be omitted. When there is no protective film 7b, it is preferable that a part or all of the second retardation region 12 has a characteristic that can also function as the protective film 7b of the polarizing film. Further, although the polarizing film 20 is also sandwiched between the two protective films 19a and 19b, the protective film 19a on the side close to the liquid crystal layer 15 may be omitted. In the embodiment shown in FIG. 3, the first retardation region 10 has a slow axis 11 orthogonal to the transmission axis 9 of the polarizing film 8 and the slow axis direction 16 of the liquid crystal molecules in the liquid crystal layer 15 during black display. It is arranged to become. In the aspect of FIG. 3, the first retardation region and the second retardation region may be disposed between the liquid crystal cell and the viewing-side polarizing film with reference to the position of the liquid crystal cell. You may arrange | position between the liquid crystal cell and the polarizing film of the back side. In the present embodiment, in any configuration, the first retardation region is disposed closer to the liquid crystal cell.

  In addition, in FIG. 3, although the aspect of the display apparatus of the transmission mode provided with the upper side polarizing plate and the lower side polarizing plate was shown, this invention may be the aspect of the reflection mode provided with only one polarizing plate, In such a case, since the optical path in the liquid crystal cell is doubled, the optimum value of Δn · d is about the above half value. The liquid crystal cell used in the present invention is not limited to the IPS mode, and any liquid crystal display device in which liquid crystal molecules are aligned substantially parallel to the surfaces of the pair of substrates during black display can be used. It can be used suitably. Examples thereof include a ferroelectric liquid crystal display device, an antiferroelectric liquid crystal display device, and an ECB type liquid crystal display device.

  The liquid crystal display device of the present invention is not limited to the configuration shown in FIGS. 1 to 3 and may include other members. For example, a color filter may be disposed between the liquid crystal layer and the polarizing film. Further, an antireflection treatment or a hard coat may be applied to the surface of the protective film of the polarizing film. Moreover, you may use what gave electroconductivity to the structural member. In the case of use as a transmission type, a cold cathode or a hot cathode fluorescent tube, or a backlight using a light emitting diode, a field emission element, or an electroluminescent element as a light source can be disposed on the back surface. In this case, the arrangement of the backlight may be on the upper side or the lower side in FIGS. In addition, a reflective polarizing plate, a diffusion plate, a prism sheet, or a light guide plate can be disposed between the liquid crystal layer and the backlight. In addition, as described above, the liquid crystal display device of the present invention may be of a reflective type. In such a case, only one polarizing plate may be disposed on the observation side, and the back side of the liquid crystal cell or the lower side of the liquid crystal cell. A reflective film is disposed on the inner surface of the substrate. Of course, it is also possible to provide a front light using the light source on the liquid crystal cell observation side.

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

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

[First phase difference region]
The first retardation region included in the liquid crystal display device of the present invention has a retardation Re (λ) at a wavelength λnm of 20 nm to 150 nm, and in order to effectively reduce oblique light leakage, Re (λ) in the retardation region is more preferably 40 nm to 115 nm, and further preferably 60 nm to 95 nm. Further, Nz defined by Nz = (nx−nz) / (nx−ny) using the in-plane refractive indexes nx and ny (nx> ny) and the refractive index nz in the thickness direction is 1.5 to 7, in order to effectively reduce light leakage in the oblique direction, Nz in the first phase difference region is more preferably 2.0 to 5.5, and 2.5 to 4.5. More preferably.

  As long as the first retardation region has the optical characteristics, the material and form thereof are basically not particularly limited. For example, a retardation film made of a birefringent polymer film, a film obtained by applying a high molecular compound on a transparent support and then heated and salted, and a low molecular weight or high molecular liquid crystalline compound applied or transferred onto the transparent support Any of the retardation films having the retardation layer formed can be used. Moreover, each can also be laminated | stacked and used.

  The birefringent polymer film is preferably a film having excellent controllability of birefringence characteristics, transparency and heat resistance. In this case, the polymer material to be used is not particularly limited as long as it is a polymer capable of achieving uniform biaxial orientation, but is preferably a conventionally known material that can be formed by a solution casting method or an extrusion method, and is preferably a norbornene-based material. Examples include polymers, polycarbonate polymers, polyarylate polymers, polyester polymers, aromatic polymers such as polysulfone, cellulose acylate, or polymers obtained by mixing two or more of these polymers. It is done.

The biaxial orientation of the film is a film made of the thermoplastic resin produced by an appropriate method such as an extrusion molding method or a casting film forming method, for example, a longitudinal stretching method using a roll, a transverse stretching method using a tenter, or a biaxial stretching method. For example, it can be achieved by performing a stretching treatment. In the longitudinal stretching method using the roll, an appropriate heating method such as a method using a heating roll, a method of heating an atmosphere, or a method of using them together can be adopted. In the biaxial stretching method using a tenter, an appropriate method such as a simultaneous biaxial stretching method using an all tenter method or a sequential biaxial stretching method using a roll tenter method can be employed.
Moreover, a thing with little orientation nonuniformity and phase difference nonuniformity is preferable. The thickness can be appropriately determined depending on the phase difference or the like, but is generally 1 to 300 μm, especially 10 to 200 μm, especially 20 to 150 μm from the viewpoint of thinning.

  As the norbornene-based polymer, norbornene and its derivatives, tetracyclododecene and its derivatives, dicyclopentadiene and its derivatives, methanotetrahydrofluorene and its monomers as a main component of a norbornene-based monomer polymer, Ring-opening polymer of norbornene-based monomer, ring-opening copolymer of norbornene-based monomer and other monomer capable of ring-opening copolymerization, addition polymer of norbornene-based monomer, copolymerizable with norbornene-based monomer Examples include addition copolymers with other monomers, and hydrogenated products thereof. Among these, from the viewpoints of heat resistance, mechanical strength, and the like, a ring-opening polymer hydride of a norbornene monomer is most preferable. The molecular weight of the norbornene-based polymer, the polymer of the monocyclic olefin or the polymer of the cyclic conjugated diene is appropriately selected according to the purpose of use, but the cyclohexane solution (toluene solution if the polymer resin does not dissolve) The polyisoprene or polystyrene-converted weight average molecular weight measured by gel permeation chromatography is usually 5,000 to 500,000, preferably 8,000 to 200,000, more preferably 10,000 to 100,000. When the thickness is in the range, the mechanical strength of the film (A) and the moldability are highly balanced, which is preferable. Typical polymers include those described in JP2003-327800A and JP2004233604A.

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

  Among these, cellulose acylate is preferred, and photographic grades are particularly preferred, and commercially available photographic grades can be obtained with satisfactory quality such as viscosity average degree of polymerization and substitution degree. Manufacturers of photographic grade cellulose triacetate include Daicel Chemical Industries, Ltd. (for example, LT-20, 30, 40, 50, 70, 35, 55, 105) and Eastman Chemical (for example, CAB-551). 0.01, CAB-551-0.02, CAB-500-5, CAB-381-0.5, CAB-381-02, CAB-381-20, CAB-321-0.2, CAP-504 0.2, CAP-482-20, CA-398-3, etc.), Coatles, Hoechst, etc., any of which can use photographic grade cellulose acylate. In addition, a plasticizer, a surfactant, a retardation modifier, a UV absorber, and the like can be mixed for the purpose of controlling the mechanical properties and optical properties of the film. Details of these additives are described in, for example, JP-A Nos. 2002-277632 and 2002-182215.

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

[Second phase difference region]
In the second retardation region of the liquid crystal display device of the present invention, the in-plane refractive indexes nx and ny are substantially equal, and the refractive index nz in the thickness direction satisfies nx <nz. Further, the retardation Rth (λ) in the thickness direction at the wavelength λnm of the second retardation region is −80 nm to −400 nm.
A more preferable range of Rth (λ) in the second retardation region varies depending on the optical characteristics of other optical members, and in particular, a protective film (for example, a triacetyl cellulose film) of a polarizing film located closer to the optical film. The Rth (λ) of the second retardation region is preferably −100 nm to −340 nm in order to effectively reduce the light leakage in the oblique direction. More preferably, it is −120 nm to −270 nm. On the other hand, nx and ny in the second phase difference region are substantially the same as described above, and Re (λ) is a value near zero.
Specifically, the in-plane retardation Re (λ) is preferably 0 to 50 nm, and more preferably 0 to 20 nm.

The second retardation region includes an optically anisotropic film of the present invention described later. The optically anisotropic film contains a liquid crystalline compound that exhibits a smectic phase, and in the film, the molecules of the liquid crystalline compound are fixed in a vertically aligned state. The second retardation region may be composed of only the optical anisotropic film or a plurality of optical anisotropic layers. Further, the second retardation region may be configured so that the entire laminated body of the support and the optically anisotropic layer satisfies the optical characteristics.
In the present specification, “substantially perpendicular” means that the angle formed by the director of the film surface and the rod-like liquid crystal compound is within a range of 70 ° to 90 °. These liquid crystalline compounds may be aligned obliquely or may be changed so that the inclination angle gradually changes (hybrid alignment). Even in the case of oblique orientation or hybrid orientation, the average inclination angle is preferably 70 ° to 90 °, more preferably 80 ° to 90 °, and most preferably 85 ° to 90 °.

Hereinafter, the optically anisotropic film of the present invention that can be used in the second retardation region will be described.
The optically anisotropic film of the present invention comprises at least one liquid crystalline compound that exhibits a smectic phase, at least one additive having chain transfer ability, and, if desired, vertically aligns the liquid crystalline compound at the air interface. Applying to the surface of the alignment film a composition containing at least one additive that promotes and / or at least one additive that promotes vertical alignment of the liquid crystalline compound at the alignment film interface; The liquid crystal compound is formed by fixing molecules in a vertical alignment state. The liquid crystalline compound is not particularly limited as long as it exhibits a smectic phase alone or in the presence of other additives. Among them, it is preferable to use a rod-like liquid crystal compound having a rod-like molecular shape.

《Bar-shaped liquid crystalline compound》
The rod-like liquid crystal compound used in the present invention may be a low molecular compound or a polymer compound, but in order to quickly form a desired alignment state, the rod-like liquid crystal compound is a polymer or oligomer. It is preferably not a low molecular compound. Moreover, in order to fix an orientation state and to form a film stably, it is preferable that the said rod-shaped liquid crystalline compound has a 2 or more polymeric group. As the polymerizable rod-like liquid crystalline compound, only one kind may be used alone, or plural kinds of the polymerizable rod-like liquid crystalline compound may be used in combination. Further, a non-polymerizable rod-like liquid crystalline compound and a polymerizable rod-like liquid crystalline compound may be used in combination. For individual liquid crystal compounds used alone or in combination, a nematic liquid crystal phase, a smectic liquid crystal phase, or a cholesteric liquid crystal phase may be formed, but the additives used when forming the optically anisotropic film of the present invention, etc. As a liquid crystal composition to be contained (for example, in the form of a coating solution containing a solvent, the solvent is volatilized in the process of heat drying), it is necessary to take a smectic liquid crystal phase within a temperature range in which the orientation is fixed.

  In this specification, the smectic phase refers to a state in which molecules aligned in one direction have a layer structure. In addition, a liquid crystalline compound having a smectic A phase is preferable from the viewpoint that each layer faces the same direction.

  Here, the rod-like smectic A liquid crystal compound is a rod-like liquid crystal compound having a temperature range showing a smectic A liquid crystal phase, and other than the smectic A liquid crystal phase if the directionality of each layer constituting the smectic is in a desired range. Liquid crystal phase (for example, it may be a compound that also shows a smectic B phase, a smectic C phase, etc.).

In general, a rod-like liquid crystalline compound is composed of a rigid unit (usually called a mesogenic group) in which two or more rings such as an aromatic ring are connected, and hydrocarbon chains substituted at both ends, but the side chain portion. Due to subtle differences in the hydrocarbon chain, the type of liquid crystal phase and the phase transition temperature change very sensitively.
In the case of having the same mesogenic group, the longer the hydrocarbon chain, the more generally it shows a smectic phase.

  The mesogenic group of the rod-like smectic A liquid crystal compound includes azomethines, azoxybenzene groups, biphenyl groups, phenyl ester groups, benzoic acid ester groups, cyclohexanecarboxylic acid phenyl ester groups, phenylcyclohexane groups, phenylpyrimidine groups, and phenyldioxane groups. , Etc. are preferably used.

  Preferred mesogenic groups exhibiting a smectic A phase include biphenyl groups, benzoic acid ester groups, and phenylpyrimidine groups. More preferred mesogenic groups include tricyclic or more phenyl groups described in JP-A-11-322678. It is a benzoic acid ester group having.

  Moreover, as a hydrocarbon group substituted on both ends of the said mesogenic group required in order to express a smectic A phase, it is preferable that it is a C3-C20 hydrocarbon group, More preferably, it is C6-C14. It is a hydrocarbon group. Preferably, it is a compound represented by the following general formula (I).

^{(V) Q 1 -L 1 -Cy} 1 -L 2 - (Cy 2 -L 3) n -Cy 3 -L 4 -Q 2
In the formula, Q ¹ and Q ² are each independently a polymerizable group, L ¹ and L ⁴ are each independently a divalent linking group, and L ² and L ³ are each independently a single bond or a divalent group. It is a linking group, Cy ¹ , Cy ² and Cy ³ are each a divalent cyclic group, and n is 0, 1 or 2.

Hereinafter, the polymerizable rod-like smectic A liquid crystalline compound represented by the general formula (V) will be described. 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 functional group capable of addition polymerization reaction or condensation polymerization reaction. Examples of polymerizable groups are shown below.

L ¹ and L ⁴ are each independently a divalent linking group. L ¹ and L ⁴ are each independently two selected from the group consisting of —O—, —S—, —CO—, —NR ² —, a divalent chain group, a divalent cyclic group, and combinations thereof. A valent linking group is preferred. R ² is an alkyl group having 1 to 7 carbon atoms or a hydrogen atom. R ² is preferably an alkyl group having 1 to 4 carbon atoms or a hydrogen atom, more preferably a methyl group, an ethyl group or a hydrogen atom, and most preferably a hydrogen atom. The example of the bivalent coupling group which consists of a combination is shown below. Here, the left side is coupled to Q (Q ¹ or Q ² ), and the right side is coupled to Cy (Cy ¹ or Cy ³ ).

L-1: —CO—O—divalent chain group —O—
L-2: -CO-O-divalent chain group -O-CO-
L-3: —CO—O—divalent chain group —O—CO—O—
L-4: -CO-O-divalent chain group -O-divalent cyclic group-
L-5: -CO-O-divalent chain group -O-divalent cyclic group -CO-O-
L-6: -CO-O-divalent chain group -O-divalent cyclic group -O-CO-
L-7: -CO-O-divalent chain group-O-divalent cyclic group-divalent chain group-
L-8: -CO-O-divalent chain group -O-divalent cyclic group -divalent chain group -CO-O-
L-9: -CO-O-divalent chain group -O-divalent cyclic group -divalent chain group -O-CO-
L-10: —CO—O—divalent chain group—O—CO—divalent cyclic group—
L-11: -CO-O-divalent chain group -O-CO-divalent cyclic group -CO-O-
L-12: -CO-O-divalent chain group -O-CO-divalent cyclic group -O-CO-
L-13: —CO—O—Divalent chain group—O—CO—Divalent cyclic group—Divalent chain group—
L-14: -CO-O-divalent chain group -O-CO-divalent cyclic group -divalent chain group -CO-O-
L-15: -CO-O-divalent chain group-O-CO-divalent cyclic group-divalent chain group-O-CO-
L-16: —CO—O—divalent chain group—O—CO—O—divalent cyclic group—
L-17: -CO-O-divalent chain group -O-CO-O-divalent cyclic group -CO-O-
L-18: -CO-O-divalent chain group -O-CO-O-divalent cyclic group -O-CO-
L-19: —CO—O—Divalent chain group—O—CO—O—Divalent cyclic group—Divalent chain group—
L-20: -CO-O-divalent chain group -O-CO-O-divalent cyclic group -divalent chain group -CO-O-
L-21: -CO-O-divalent chain group -O-CO-O-divalent cyclic group -divalent chain group -O-CO-

The divalent chain group means an alkylene group, a substituted alkylene group, an alkenylene group, a substituted alkenylene group, an alkynylene group, or a substituted alkynylene group. An alkylene group, a substituted alkylene group, an alkenylene group and a substituted alkenylene group are preferred, and an alkylene group and an alkenylene group are more preferred.
The alkylene group may have a branch. The alkylene group preferably has 1 to 12 carbon atoms, more preferably 2 to 10 carbon atoms, and most preferably 2 to 8 carbon atoms. The alkylene part of the substituted alkylene group is the same as the above alkylene group. Examples of the substituent include a halogen atom.
The alkenylene group may have a branch. The alkenylene group preferably has 2 to 12 carbon atoms, more preferably 2 to 10 carbon atoms, and most preferably 2 to 8 carbon atoms. The alkenylene part of the substituted alkenylene group is the same as the above alkenylene group.
Examples of the substituent include a halogen atom.
The alkynylene group may have a branch. The alkynylene group preferably has 2 to 12 carbon atoms, more preferably 2 to 10 carbon atoms, and most preferably 2 to 8 carbon atoms. The alkynylene part of the substituted alkynylene group is the same as the above alkynylene group.
Examples of the substituent include a halogen atom.
Specific examples of the divalent chain group include ethylene, trimethylene, propylene, tetramethylene, 2-methyl-tetramethylene, pentamethylene, hexamethylene, octamethylene, 2-butenylene, 2-butynylene and the like.

The definition and examples of the divalent cyclic group are the same as those of Cy ¹ , Cy ² and Cy ³ described later.

L ² and L ³ are each independently a single bond or a divalent linking group. L ² and L ³ are each independently two selected from the group consisting of —O—, —S—, —CO—, —NR ² —, a divalent chain group, a divalent cyclic group, and combinations thereof. A valent linking group or a single bond is preferred.
R ² is an alkyl group having 1 to 7 carbon atoms or a hydrogen atom, preferably an alkyl group having 1 to 4 carbon atoms or a hydrogen atom, and preferably a methyl group, an ethyl group, or a hydrogen atom. More preferably, it is a hydrogen atom. The divalent chain group and the divalent cyclic group have the same definitions as L ¹ and L ⁴ .

In the formula (V), n is 0, 1 or 2. When n is 2, two L ³ may be the same or different, and two Cy ² may be the same or different. n is preferably 1 or 2, and more preferably 1.

In the formula (V), Cy ¹ , Cy ² and Cy ³ are each independently a divalent cyclic group.
The ring contained in the cyclic group is preferably a 5-membered ring, a 6-membered ring or a 7-membered ring, more preferably a 5-membered ring or a 6-membered ring, and most preferably a 6-membered ring. The ring contained in the cyclic group may be a condensed ring. However, it is more preferably a monocycle than a condensed ring. The ring contained in the cyclic group may be any of an aromatic ring, an aliphatic ring, and a heterocyclic ring. Examples of the aromatic ring include a benzene ring and a naphthalene ring. Examples of the aliphatic ring include a cyclohexane ring. Examples of the heterocyclic ring include a pyridine ring and a pyrimidine ring. As the cyclic group having a benzene ring, 1,4-phenylene is preferable. As the cyclic group having a naphthalene ring, naphthalene-1,5-diyl and naphthalene-2,6-diyl are preferable. The cyclic group having a cyclohexane ring is preferably 1,4-cyclohexylene. As the cyclic group having a pyridine ring, pyridine-2,5-diyl is preferable. The cyclic group having a pyrimidine ring is preferably pyrimidine-2,5-diyl. The cyclic group may have a substituent. Examples of the substituent include a halogen atom, a cyano group, a nitro group, an alkyl group having 1 to 5 carbon atoms, a halogen-substituted alkyl group having 1 to 5 carbon atoms, and an alkoxy group having 1 to 5 carbon atoms. , An alkylthio group having 1 to 5 carbon atoms, an acyloxy group having 2 to 6 carbon atoms, an alkoxycarbonyl group having 2 to 6 carbon atoms, a carbamoyl group, and an alkyl-substituted carbamoyl group having 2 to 6 carbon atoms And an acylamino group having 2 to 6 carbon atoms.

  Below, the example of the rod-shaped smectic A liquid crystalline compound which has a polymeric group represented by Formula (V) is shown. The present invention is not limited to these.

<< Additives with chain transfer ability >>
When the optically anisotropic film is formed from a composition containing an additive having chain transfer ability, that is, when a liquid crystalline compound is polymerized using an additive having chain transfer ability, bright spots and haze generated. Can be eliminated. Additives with chain transfer ability indicate a material that reacts with growing radicals during radical polymerization, stops increasing the polymer chain length, and generates low-molecular radicals that have restarting ability and are produced without reducing the polymerization reaction rate. It has a function of reducing the molecular weight of the polymer. Representative compounds and chain transfer mechanisms of additives having chain transfer ability are described in NTS publication, supervised by Mikiharu Tsunoike, Takeshi Endo, radical polymerization handbook 1999, 38p-48p.
Although generally known additives can be used as specific additives having chain transfer ability, compounds having a mercapto group (thiol compounds such as dodecyl mercaptan, octyl mercaptan, trimethylolpropane tris (3- Mercaptopropionate), pentaerythritol tetrakis (3-mercaptopropionate) and the like) and disulfide compounds (eg diphenyl disulfide).
Compatibility with the liquid crystal compound is also required, and a thiol compound exhibiting liquid crystallinity is more preferable from the viewpoint of compatibility.
Examples of the thiol compound exhibiting liquid crystallinity include compounds described in US Pat. No. 6,096,241.
The addition amount of the additive having chain transfer ability is preferably 0.01 to 10% by mass, more preferably 0.05 to 5% by mass, and 0.05 to 4% by mass with respect to the liquid crystal compound. % Is more preferable.

<< Vertical alignment accelerator on the interface side of the alignment film >>
In the composition used for forming the optically anisotropic film of the present invention, an additive for promoting vertical alignment on the alignment film interface side of the molecules of the rod-like liquid crystalline compound (hereinafter referred to as “alignment film interface side vertical alignment promotion”). May also be added). The content of the vertical alignment accelerator on the alignment film interface side in the composition is preferably 0.01 to 10% by mass, more preferably 0.05 to 5% by mass with respect to the liquid crystal compound. More preferably, it is 0.05-4 mass%. The alignment film interface-side vertical alignment accelerator contributes to vertically aligning the molecules of the liquid crystal compound on the alignment film interface side. An onium salt can be suitably used as the alignment film interface side vertical alignment accelerator.
Examples of the onium salts include onium salts such as ammonium salts, sulfonium salts, and phosphonium salts. A quaternary onium salt is preferable, and a quaternary ammonium salt is particularly preferable.

  Quaternary ammonium is generally a tertiary amine (eg, trimethylamine, triethylamine, tributylamine, triethanolamine, N-methylpyrrolidine, N-methylpiperidine, N, N-dimethylpiperazine, triethylenediamine, N, N, N ', N'-tetramethylethylenediamine etc.) or nitrogen-containing heterocycle (pyridine ring, picoline ring, 2,2'-bipyridyl ring, 4,4'-bipyridyl ring, 1,10-phenanthroline ring, quinoline ring, oxazole ring , Thiazole ring, N-methylimidazole ring, pyrazine ring, tetrazole ring, etc.) can be obtained by alkylation (Menstokin reaction), alkenylation, alkynylation or arylation.

  As the quaternary ammonium salt, a quaternary ammonium salt composed of a nitrogen-containing heterocyclic ring is preferable, and a quaternary pyridinium salt is particularly preferable. More specifically, the quaternary ammonium salt is preferably selected from quaternary pyridinium salts represented by the following general formula (3a) or a general formula (3b) described later.

In the formula (3a), R ⁸ represents a substituted or unsubstituted alkyl group, alkenyl group, alkynyl group, aralkyl group, aryl group or heterocyclic group, D represents a hydrogen bonding group, and m represents 1 to 3 X ⁻ represents an anion.

First, the general formula (3a) will be described.
The alkyl group represented by R ⁸ is preferably a substituted or unsubstituted alkyl group having 1 to 18 carbon atoms, and more preferably a substituted or unsubstituted alkyl group having 1 to 8 carbon atoms. These may be linear, branched or cyclic. Examples of these include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, n-hexyl, n-octyl, neopentyl, cyclohexyl, adamantyl and cyclopropyl.

  Examples of the substituent of the alkyl group include the following. A substituted or unsubstituted alkenyl group having 2 to 18 carbon atoms (preferably 2 to 8 carbon atoms) (eg, vinyl); a substituted or unsubstituted alkynyl group having 2 to 18 carbon atoms (preferably having 2 to 8 carbon atoms) (Eg, ethynyl); substituted or unsubstituted aryl group having 6 to 10 carbon atoms (eg, phenyl, naphthyl); halogen atom (eg, F, Cl, Br, etc.); 1-8) substituted or unsubstituted alkoxy group (eg, methoxy, ethoxy); C6-C10 substituted or unsubstituted aryloxy group (eg, phenoxy, biphenyloxy, p-methoxyphenoxy); carbon number A substituted or unsubstituted alkylthio group having 1 to 18 (preferably 1 to 8 carbon atoms) (eg, methylthio, ethylthio); a substituted or unsubstituted arylthio having 6 to 10 carbon atoms (E.g., phenylthio); a substituted or unsubstituted acyl group having 2 to 18 carbon atoms (preferably 2 to 8 carbon atoms) (e.g., acetyl, propionyl);

  C1-C18 (preferably C1-C8) substituted or unsubstituted alkylsulfonyl group or arylsulfonyl group (e.g., methanesulfonyl, p-toluenesulfonyl); C2-C18 (preferably C2-C2) To 8) substituted or unsubstituted acyloxy groups (eg, acetoxy, propionyloxy); substituted or unsubstituted alkoxycarbonyl groups (eg, methoxycarbonyl, ethoxy) having 2 to 18 carbon atoms (preferably 2 to 8 carbon atoms). A substituted or unsubstituted aryloxycarbonyl group having 7 to 11 carbon atoms (eg, naphthoxycarbonyl); an unsubstituted amino group or a substituted amino group having 1 to 18 carbon atoms (preferably having 1 to 8 carbon atoms) Groups (eg methylamino, dimethylamino, diethylamino, anilino, methoxyphenylamino, chloro Phenylamino, pyridylamino, methoxycarbonylamino, n-butoxycarbonylamino, phenoxycarbonylamino, methylcarbamoylamino, ethylthiocarbamoylamino, phenylcarbamoylamino, acetylamino, ethylcarbonylamino, ethylthiocarbamoylamino, cyclohexylcarbonylamino, benzoylamino , Chloroacetylamino, methylsulfonylamino);

  A substituted or unsubstituted carbamoyl group having 1 to 18 carbon atoms (preferably 1 to 8 carbon atoms) (eg, unsubstituted carbamoyl, methylcarbamoyl, ethylcarbamoyl, n-butylcarbamoyl, t-butylcarbamoyl, dimethylcarbamoyl, morpholino) Carbamoyl, pyrrolidinocarbamoyl); unsubstituted sulfamoyl group, or substituted sulfamoyl group having 1 to 18 carbon atoms (preferably 1 to 8 carbon atoms) (eg, methylsulfamoyl, phenylsulfamoyl); cyano group; nitro group Group; carboxy group; hydroxyl group; heterocyclic group (eg, oxazole ring, benzoxazole ring, thiazole ring, benzothiazole ring, imidazole ring, benzimidazole ring, indolenine ring, pyridine ring, piperidine ring, pyrrolidine ring, morpholine ring, Sulfolane ring, Orchid ring, thiophene ring, pyrazole ring, pyrrole ring, chroman ring, a coumarin ring). The substituent for the alkyl group is particularly preferably an aryloxy group, an arylthio group, an arylsulfonyl group, or an aryloxycarbonyl group.

The alkenyl group represented by R ⁸ is preferably a substituted or unsubstituted alkenyl group having 2 to 18 carbon atoms, more preferably a substituted or unsubstituted alkenyl group having 2 to 8 carbon atoms, such as vinyl, Examples include allyl, 1-propenyl, 1,3-butadienyl and the like.
As the substituent for the alkenyl group, those exemplified as the substituent for the alkyl group are preferable.

The alkynyl group represented by R ⁸ is preferably a substituted or unsubstituted alkynyl group having 2 to 18 carbon atoms, more preferably a substituted or unsubstituted alkynyl group having 2 to 8 carbon atoms, such as ethynyl, 2-propynyl etc. are mentioned. As the substituent for the alkynyl group, those exemplified as the substituent for the alkyl group are preferable.

The aralkyl group represented by R ⁸ is preferably a substituted or unsubstituted aralkyl group having 7 to 18 carbon atoms, such as benzyl, methylbenzyl, biphenylmethyl, naphthylmethyl, and the like. Examples of the substituent for the aralkyl group include those exemplified as the substituent for the alkyl group.

The aryl group represented by R ⁸ is preferably a substituted or unsubstituted aryl group having 6 to 18 carbon atoms, and examples thereof include phenyl, naphthyl, and fluorenyl. As the substituent for the aryl group, those exemplified as the substituent for the alkyl group are preferable. Besides these, an alkyl group (for example, methyl, ethyl, etc.), an alkynyl group, and a benzoyl group are also preferable.

The heterocyclic group represented by R ⁸ is a 5- or 6-membered saturated or unsaturated heterocyclic ring composed of a carbon atom, a nitrogen atom, an oxygen atom or a sulfur atom, and examples thereof include oxazole Ring, benzoxazole ring, thiazole ring, benzothiazole ring, imidazole ring, benzimidazole ring, indolenine ring, pyridine ring, piperidine ring, pyrrolidine ring, morpholine ring, sulfolane ring, furan ring, thiophene ring, pyrazole ring, pyrrole ring , Chroman ring, and coumarin ring. The heterocyclic group may be substituted, and as the substituent in that case, those exemplified as the substituent of the alkyl group are preferable. As the heterocyclic group represented by R ⁸ , a benzoxazole ring and a benzothiazole ring are particularly preferable.

R ⁸ is preferably a substituted or unsubstituted alkyl group, aralkyl group, aryl group or heterocyclic group.

  D represents a hydrogen bonding group. Hydrogen bonds exist between electrically negative atoms (eg, O, N, F, Cl) and hydrogen atoms covalently bonded to similarly electronegative atoms. As a theoretical interpretation of hydrogen bonding, for example, H.H. Unneyama and K.M. There are reports in Morokuma, Journal of American Chemical Society, Vol. 99, pp. 1316-1332, 1977. Specific examples of hydrogen bonding include J. N. Examples include Israes Ativiri, Yasuo Kondo, Hiroyuki Oshima, Intermolecular Force and Surface Force, McGraw Hill, 1991, page 98, FIG. Specific examples of hydrogen bonding include, for example, G.I. R. Examples include those described in Desiraju, Angewent Chemistry International Edition England, Vol. 34, p. 2311, 1995.

  Preferred hydrogen bonding groups include mercapto groups, hydroxy groups, amino groups, carbonamido groups, sulfonamido groups, acid amide groups, ureido groups, carbamoyl groups, carboxyl groups, sulfo groups, nitrogen-containing heterocyclic groups (for example, imidazolyl). Group, benzimidazolyl group, pyrazolyl group, pyridyl group, 1,3,5-triazyl group, pyrimidyl group, pyridazyl group, quinolyl group, benzimidazolyl group, benzthiazolyl group, succinimide group, phthalimide group, maleimide group, uracil group, thiouracil Group, barbituric acid group, hydantoin group, maleic hydrazide group, isatin group, uramil group and the like. More preferred hydrogen bonding groups include amino group, carbonamido group, sulfonamido group, ureido group, carbamoyl group, carboxyl group, sulfo group, and pyridyl group, and particularly preferred are amino group, carbamoyl group, A pyridyl group can be mentioned.

The anion represented by X ⁻ may be either an inorganic anion or an organic anion, such as a halogen anion (eg, fluorine ion, chlorine ion, bromine ion, iodine ion), sulfonate ion (eg, methanesulfone). Acid ion, trifluoromethanesulfonic acid ion, methylsulfuric acid ion, p-toluenesulfonic acid ion, p-chlorobenzenesulfonic acid ion, 1,3-benzenedisulfonic acid ion, 1,5-naphthalenedisulfonic acid ion, 2,6-naphthalene Disulfonate ions, etc.), sulfate ions, thiocyanate ions, perchlorate ions, tetrafluoroborate ions, picrate ions, acetate ions, phosphate ions (for example, hexafluorophosphate ions), hydroxide ions, etc. .
X ⁻ is preferably a halogen anion, a sulfonate ion, or a hydroxide ion. X ⁻ need not be a monovalent anion and may be a divalent or higher anion. In such a case, the ratio of the cation to the anion in the compound need not be 1: 1, It is determined.

  In the general formula (3a), m is preferably 1.

  Next, the general formula (3b) will be described.

In the formula (3b), R ⁹ and R ¹⁰ each represents a substituted or unsubstituted alkyl group, alkenyl group, alkynyl group, aralkyl group, aryl group or heterocyclic group, and X— represents an anion.
The substituted or unsubstituted alkyl group, alkenyl group, alkynyl group, aralkyl group, aryl group or heterocyclic group represented by R ⁹ and R ¹⁰ respectively is represented by R ⁸ in the general formula (3a). It is synonymous with a group, and its preferable range is also the same. X ^- anion represented by the In the general formula (3a), X ^- has the same meaning as anion represented by, and the preferable ranges thereof are also the same. As described above, X ⁻ need not be a monovalent anion but may be a divalent or higher anion. In such a case, the ratio of the cation to the anion in the compound should be 1: 2. It is not determined.

  Specific examples of onium salts that can be used in the present invention are shown below, but the onium salts used in the present invention are not limited thereto. In the following specific examples, no. II-1 to 12 are general formulas (3b), No. II-13 to 32 are examples of the compound represented by the general formula (3a).

  Moreover, the quaternary ammonium salt of following (1)-(19) is also preferable.

《Air interface vertical alignment agent》
In the composition used for forming the optically anisotropic film of the present invention, an additive that promotes vertical alignment on the air interface side of the molecules of the rod-like liquid crystalline compound (hereinafter referred to as “air interface side vertical alignment accelerator”). May be added). The content of the air interface vertical alignment agent in the composition is preferably 0.01 to 10% by mass, more preferably 0.05 to 5% by mass, based on the liquid crystal compound. More preferably, it is -4 mass%. Usually, since the liquid crystalline compound has a property of being inclined and aligned on the air interface side, it is necessary to control the alignment of the liquid crystalline compound vertically on the air interface side in order to obtain a uniformly vertically aligned state. . The air interface vertical alignment accelerator is unevenly distributed on the air interface side, and contributes to vertically aligning the molecules of the liquid crystal compound by its excluded volume effect and electrostatic effect.

  As the air interface vertical alignment agent, compounds described in JP-A Nos. 2002-20363 and 2002-129162 can be used. Also, paragraph numbers [0072] to [0075] of Japanese Patent Application Laid-Open No. 2004-53981, paragraph numbers [0071] to [0078] of Japanese Patent Application Laid-Open No. 2004-4688, and paragraphs of Japanese Patent Application Laid-Open No. 2004-139015. The matters described in the numbers [0052] to [0054], [0065] to [0066], and [0092] to [0094] can be appropriately applied to the present invention. Examples of the air interface vertical alignment agent include the following compounds D-1 to D-33, compounds C-1 to C-45, compounds Q-1 to Q-26, and I-1 to I-62. included.

<< Other materials in the composition for forming an optically anisotropic film >>
In the composition such as a coating solution used for forming the optically anisotropic film of the present invention, a liquid crystal compound, and the alignment film interface-side vertical alignment accelerator and air interface-side vertical alignment that are optionally added. In addition to the accelerator, it may contain a polymerization initiator, a plasticizer, a surfactant, a polymerizable monomer, and the like. These materials are added for various purposes, for example, for the purpose of fixing the orientation, uniformity of the coating film, strength of the film, and improving the orientation of the liquid crystal compound. These materials are preferably compatible with the liquid crystal compound used in combination and do not inhibit the alignment.

As the polymerization initiator, either a thermal polymerization initiator or a photopolymerization initiator may be used. Photoinitiators are preferred. Examples of the photopolymerization initiator include α-carbonyl compounds (described in US Pat. Nos. 2,367,661 and 2,367,670), acyloin ether (described in US Pat. No. 2,448,828), α-hydrocarbon substituted aromatic acyloin. Compound (described in US Pat. No. 2,722,512), polynuclear quinone compound (described in US Pat. Nos. 3,046,127 and 2,951,758), a combination of triarylimidazole dimer and p-aminophenyl ketone (US Pat. No. 3,549,367) Description), acridine and phenazine compounds (JP-A-60-105667, U.S. Pat. No. 4,239,850) and oxadiazole compounds (U.S. Pat. No. 4,212,970).
The amount of the photopolymerization initiator used is preferably 0.01 to 20% by mass, more preferably 0.5 to 5% by mass, based on the solid content of the coating solution.

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

  Examples of the surfactant include conventionally known compounds, and fluorine compounds are particularly preferable. Specific examples include compounds described in paragraph numbers [0028] to [0056] in JP-A-2001-330725. Examples of the surfactant that can be used in the present invention include the following compounds P-1 to P-71.

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

<< Method for producing optically anisotropic film >>
The optically anisotropic film of the present invention is prepared by preparing a coating liquid containing a liquid crystalline compound and, if desired, other additives such as the above-described air interface vertical alignment agent and polymerization initiator. When applied to the surface, the liquid crystal compound molecules can be vertically aligned to form a smectic phase, and the alignment can be fixed. When formed on the temporary support, the formed optically anisotropic film is transferred onto the support. Furthermore, not only one optically anisotropic layer but also a plurality of optically anisotropic layers can be laminated to form the second retardation region exhibiting the above optical characteristics. Further, the second retardation region may be produced so that the entire laminated body of the support and the optically anisotropic layer satisfies the optical characteristics.

"solvent"
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).

After the molecules of the liquid crystal compound are vertically aligned to form a smectic phase, it is preferable to fix the molecules in the alignment state. The immobilization can be carried out by a polymerization reaction of a liquid crystalline compound, or when a polymerizable monomer is added separately, by a polymerization reaction of a liquid compound and a polymerizable monomer. For the polymerization reaction carried out for immobilization, it is preferable to use a photopolymerization reaction using a photopolymerization initiator. It is preferable to use ultraviolet rays for light irradiation for polymerization of liquid crystalline molecules. The irradiation energy is preferably ^{20mJ / cm 2 ~50J / cm 2} , further preferably 100 to 800 mJ / cm ^2. In order to accelerate the photopolymerization reaction, light irradiation may be performed under heating conditions.

The thickness of the optically anisotropic film is preferably 0.1 to 10 μm, more preferably 0.5 to 5 μm, and most preferably 1 to 5 μm.
Please include additional information.

  When the uniformity of alignment was examined in detail, it was found that after applying the composition, holding the liquid crystal / isotropic phase transition temperature or higher and then cooling to a smectic phase significantly reduces alignment defects. I found. The temperature above the transition temperature is preferably 0.1 ° or higher, more preferably 1 ° or higher, and further preferably 5 ° to 20 °. It has been found that defects are almost eliminated by maintaining the heat treatment time in the isotropic phase for 10 seconds or more. More preferably, it is 20 seconds or more, and further preferably 30 seconds or more and 3 minutes or less.

《Alignment film》
For the production of the optically anisotropic film of the present invention, an alignment film is used. The alignment film has a function of defining the alignment direction of the liquid crystalline molecules. The optically anisotropic film of the present invention is prepared by homeotropic alignment of rod-like liquid crystalline molecules, so that it is not necessary to regulate the in-plane alignment, but the alignment film improves and improves alignment uniformity. It is used for the purpose of improving the adhesion between the polymer substrate used as a body and the optically anisotropic film. However, the present invention relates to a homeotropically aligned liquid crystal composition, and since there is no in-plane alignment direction, an alignment film is not essential in the present invention. However, since the alignment film can improve the uniformity of alignment of the liquid crystalline composition or improve the adhesion between the polymer substrate and the optically anisotropic layer, it can be used if necessary. it can. Note that if the alignment state of the liquid crystalline compound is fixed after the alignment, the alignment film plays the role and can be removed. That is, only the optically anisotropic film on the alignment film in which the alignment state is fixed may be transferred onto another support or a polarizer.

  The alignment film is an organic compound (eg, ω-tricosanoic acid) formed by rubbing treatment of an organic compound (preferably a polymer), oblique deposition of an inorganic compound, formation of a layer having a microgroove, or Langmuir-Blodgett method (LB film). , Dioctadecylmethylammonium chloride, methyl stearylate). Furthermore, an alignment film in which an alignment function is generated by application of an electric field, application of a magnetic field, or light irradiation is also known.

  When the liquid crystal composition of the present invention is used, the rod-like liquid crystalline compound can be vertically aligned even if an alignment film used for horizontal alignment is used. That is, the rod-like liquid crystalline compound can be vertically aligned without using a so-called vertical alignment film having an excluded volume group or a hydrophobic group, or an alignment film subjected to a vertical alignment treatment with an inorganic salt addition or a surfactant.

The alignment film can be rubbed if necessary. In principle, the polymer used for the alignment film has a molecular structure having a function of aligning liquid crystal molecules.
In the present invention, in addition to the function of aligning liquid crystalline molecules, a crosslink having a function of aligning a side chain having a crosslinkable functional group (eg, double bond) to the main chain or aligning liquid crystalline molecules. It is preferable to introduce a functional functional group into the side chain.
As the polymer used for the alignment film, either a polymer that can be crosslinked by itself or a polymer that is crosslinked by a crosslinking agent can be used, and a plurality of combinations thereof can be used.

  Examples of the polymer include, for example, methacrylate polymer, styrene polymer, polyolefin, polyvinyl alcohol and modified polyvinyl alcohol, poly (N-methylolacrylamide) described in paragraph No. [0022] of JP-A-8-338913. , Polyester, polyimide, vinyl acetate polymer, carboxymethyl cellulose, polycarbonate and the like. Silane coupling agents can be used as the polymer. Water-soluble polymers (eg, poly (N-methylolacrylamide), carboxymethylcellulose, gelatin, polyvinyl alcohol, modified polyvinyl alcohol) are preferred, gelatin, polyvinyl alcohol and modified polyvinyl alcohol are more preferred, and polyvinyl alcohol and modified polyvinyl alcohol are most preferred. . It is particularly preferable to use two types of polyvinyl alcohol or modified polyvinyl alcohol having different degrees of polymerization.

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

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

When a side chain having a crosslinkable functional group is bonded to the main chain of the alignment film polymer, or a crosslinkable functional group is introduced into a side chain having a function of aligning liquid crystalline molecules, the alignment film polymer and the optically anisotropic film The polyfunctional monomer contained in the conductive layer can be copolymerized. As a result, not only between the polyfunctional monomer and the polyfunctional monomer, but also between the alignment film polymer and the alignment film polymer and between the polyfunctional monomer and the alignment film polymer is firmly bonded by a covalent bond. Therefore, the strength of the optical compensation sheet can be remarkably improved by introducing the crosslinkable functional group into the alignment film polymer.
The crosslinkable functional group of the alignment film polymer preferably contains a polymerizable group in the same manner as the polyfunctional monomer. Specific examples include those described in paragraphs [0080] to [0100] in JP-A-2000-155216.

Apart from the crosslinkable functional group, the alignment film polymer can also be crosslinked using a crosslinking agent.
Examples of the crosslinking agent include aldehydes, N-methylol compounds, dioxane derivatives, compounds that act by activating carboxyl groups, active vinyl compounds, active halogen compounds, isoxazole and dialdehyde starch. Two or more kinds of crosslinking agents may be used in combination. Specific examples include compounds described in paragraphs [0023] to [024] in JP-A No. 2002-62426. Aldehydes having high reaction activity, particularly glutaraldehyde are preferred.

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

  The alignment film is basically formed by applying the above-mentioned polymer as an alignment film forming material and a transparent support containing a crosslinking agent, followed by drying by heating (crosslinking) and, if necessary, rubbing treatment. Can do. As described above, the crosslinking reaction may be performed at an arbitrary time after coating on the transparent support. When a water-soluble polymer such as polyvinyl alcohol is used as the alignment film forming material, the coating solution is preferably a mixed solvent of an organic solvent (eg, methanol) having a defoaming action and water. The ratio by mass is water: methanol greater than 0 and 99 or less: less than 100, preferably 1 or more, and more preferably greater than 0 and 91 or less: less than 100, 9 or more. Thereby, generation | occurrence | production of a bubble is suppressed and the defect of the layer surface of an orientation film and also an optically anisotropic layer reduces remarkably.

  The coating method for forming the alignment film is preferably a spin coating method, a dip coating method, a curtain coating method, an extrusion coating method, a rod coating method or a roll coating method. A rod coating method is particularly preferable. The film thickness after drying is preferably 0.1 to 10 μm. Heat drying can be performed at 20 to 110 degrees. In order to form sufficient cross-linking, 60 ° to 100 ° is preferable, and 80 ° to 100 ° is particularly preferable. The drying time can be 1 minute to 36 hours, preferably 1 minute to 30 minutes. The pH is also preferably set to an optimum value for the crosslinking agent to be used. When glutaraldehyde is used, the pH is 4.5 to 5.5, and 4.8 to 5.2 is particularly preferable.

  The alignment film is provided on the transparent support or the undercoat layer. The alignment film can be obtained by cross-linking the polymer layer as described above and, if necessary, rubbing the surface.

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

[Support]
The optically anisotropic film of the present invention may be formed on a support. The support is preferably transparent, and specifically, the light transmittance is preferably 80% or more. The support preferably has a small wavelength dispersion. Specifically, the Re400 / Re700 ratio is preferably less than 1.2. Among these, a polymer film is preferable. The support for the optically anisotropic film may be a part of the second retardation region, or a part or the whole of the first retardation region. The support for the optically anisotropic film may also function as a protective film for the polarizing film.

  The optical anisotropy of the support is preferably small, and the in-plane retardation Re (λ) is preferably 20 nm or less, more preferably 10 nm or less, and most preferably 5 nm or less. Moreover, when it serves also as a 1st phase difference area | region, retardation Re ((lambda)) is 20 nm-150 nm, It is more preferable that it is 40 nm-115 nm, It is more preferable that it is 60 nm-95 nm. Moreover, Nz is 1.5-7, it is more preferable that it is 2.0-5.5, and it is further more preferable that it is 2.5-4.5.

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

[Protective film for polarizing film]
As the first and second protective films for the polarizing film, those having no absorption in the visible light region, a light transmittance of 80% or more, and a retardation based on birefringence are preferable. Specifically, the in-plane Re (λ) is preferably 0 to 30 nm, more preferably 0 to 15 nm, and most preferably 0 to 5 nm. Furthermore, the retardation Rth (λ) in the thickness direction is preferably 0 to 40 nm, more preferably 0 to 20 nm, and most preferably 0 to 10 nm. Any film having this property can be preferably used, but from the viewpoint of durability of the polarizing film, a cellulose acylate or norbornene film is more preferable. As a method for reducing Rth (λ) of a cellulose acylate film, a method described in JP-A Nos. 11-246704 and 2001-247717, a compound represented by the following general formula (13) or (14) The method of containing is mentioned.

[Wherein, R ¹ represents an alkyl group or an aryl group, and R ² and R ³ each independently represents a hydrogen atom, an alkyl group, or an aryl group. The total number of carbon atoms of R ¹ , R ² and R ³ is 10 or more, and each of the alkyl group and aryl group may have a substituent. ]

[Wherein, R ⁴ and R ⁵ each independently represents an alkyl group or an aryl group. The total number of carbon atoms of R ⁴ and R ⁵ is 10 or more, and each of the alkyl group and aryl group may have a substituent. ]

In the general formula (13), R ¹ represents an alkyl group or an aryl group, and R ² and R ³ each independently represent a hydrogen atom, an alkyl group, or an aryl group. Further, the total number of carbon atoms of R ¹ , R ² and R ³ is particularly preferably 10 or more. In the general formula (14), R ⁴ and R ⁵ each independently represents an alkyl group or an aryl group. The total number of carbon atoms of R ⁴ and R ⁵ is 10 or more, and each of the alkyl group and aryl group may have a substituent. As the substituent, a fluorine atom, an alkyl group, an aryl group, an alkoxy group, a sulfone group, and a sulfonamide group are preferable, and an alkyl group, an aryl group, an alkoxy group, a sulfone group, and a sulfonamide group are particularly preferable. Further, the alkyl group may be linear, branched or cyclic, and preferably has 1 to 25 carbon atoms, more preferably 6 to 25, and more preferably 6 to 20 (E.g., methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, amyl, isoamyl, t-amyl, hexyl, cyclohexyl, heptyl, octyl, bicyclooctyl, nonyl, adamantyl, decyl, t-octyl, undecyl, Dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, didecyl) are particularly preferred. As the aryl group, those having 6 to 30 carbon atoms are preferable, and those having 6 to 24 carbon atoms (for example, phenyl, biphenyl, terphenyl, naphthyl, binaphthyl, triphenylphenyl) are particularly preferable. Although the preferable example of a compound represented by General formula (13) or General formula (14) is shown below, this invention is not limited to these specific examples.

  Rth can also be reduced by reducing the thickness of the cellulose acylate film. The thickness of the cellulose sylate film as the protective film for the first and second polarizing films is preferably 10 to 100 μm, more preferably 10 to 60 μm, and still more preferably 20 to 45 μm.

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

<Preparation of IPS mode liquid crystal cell 1>
As shown in FIG. 1, electrodes (2 and 3 in FIG. 1) are arranged on one glass substrate so that the distance between adjacent electrodes is 20 μm, and a polyimide film is used as an alignment film on it. A rubbing process was performed. The rubbing process was performed in the direction 4 shown in FIG. A polyimide film was provided on one surface of a separately prepared glass substrate, and a rubbing treatment was performed to obtain an alignment film. The two glass substrates are stacked and bonded so that the alignment films face each other, the distance between the substrates (gap; d) is 3.9 μm, and the rubbing directions of the two glass substrates are parallel. A nematic liquid crystal composition having a refractive index anisotropy (Δn) of 0.0769 and a dielectric anisotropy (Δε) of 4.5 was enclosed. The value of d · Δn of the liquid crystal layer was 300 nm.

<Production of First Phase Difference Region 1, First Phase Difference Region 2, and First Phase Difference Region 3>
The following composition was put into a mixing tank and stirred while heating to dissolve each component to prepare a cellulose acetate solution. The solution was filtered using a filter paper (No. 63, manufactured by Advantech) having a retained particle diameter of 4 μm and a drainage time of 35 seconds at 5 kg / cm ² or less.

────────────────────────────────────
Cellulose acetate solution composition ────────────────────────────────────
Cellulose acetate having an acetylation degree of 60.9% (degree of polymerization: 300, Mn / Mw = 1.5) 100 parts by weight Triphenyl phosphate (plasticizer) 7.8 parts by weight Biphenyl diphenyl phosphate (plasticizer) 3.9 parts by weight Methylene chloride (first solvent) 300 parts by weight Methanol (second solvent) 54 parts by weight 1-butanol (third solvent) 11 parts by weight ──────────────────── ────────────────

  In another mixing tank, 8 parts by mass of the following retardation increasing agent A, 10 parts by mass of retardation increasing agent B, 0.28 parts by mass of silicon dioxide fine particles (average particle size: 0.1 μm), 80 parts by mass of methylene chloride And 20 parts by mass of methanol were added and stirred while heating to prepare a retardation increasing agent solution (and a fine particle dispersion). The dope was prepared by mixing 474 parts by mass of the cellulose acetate solution with 40 parts by mass of the retardation increasing agent solution and stirring sufficiently.

  The obtained dope was cast using a band casting machine. A film having a residual solvent amount of 15% by mass was stretched transversely at a stretch ratio of 20% using a tenter under the conditions of 130 ° C., held at 50 ° C. for 30 seconds with the stretched width, and then clipped to remove cellulose. An acetate film was prepared. The residual solvent amount at the end of stretching was 5% by mass, and further dried to prepare a film with the residual solvent amount being less than 0.1% by mass.

  The thickness of the film thus obtained (first retardation region 1) was 80 μm. About the produced 1st phase difference area | region 1, Re is 70 nm by measuring the light incident angle dependence of Re using an automatic birefringence meter (KOBRA-21ADH, Oji Scientific Instruments Co., Ltd. product). It was found that Rth was 175 nm and Nz was 3.0.

  In another mixing tank, 16 parts by mass of the above-mentioned retardation increasing agent A, 8 parts by mass of retardation increasing agent B, 0.28 parts by mass of silicon dioxide fine particles (average particle size: 0.1 μm), 80 parts by mass of methylene chloride And 20 parts by mass of methanol were added and stirred while heating to prepare a retardation increasing agent solution (and a fine particle dispersion). 45 parts by mass of the retardation increasing agent solution was mixed with 474 parts by mass of the cellulose acetate solution, and the dope was prepared by sufficiently stirring to form a film in the same manner as in the first retardation region 1 described above. The thickness of the film thus obtained (first retardation region 2) was 80 μm. About the produced 1st phase difference area | region 2, Re is 60 nm by measuring the light incident angle dependence of Re using an automatic birefringence meter (KOBRA-21ADH, Oji Scientific Instruments Co., Ltd. product). It was found that Rth was 210 nm and Nz was 4.0.

  In another mixing tank, 18 parts by mass of the retardation increasing agent A, 0.28 parts by mass of silicon dioxide fine particles (average particle size: 0.1 μm), 80 parts by mass of methylene chloride and 20 parts by mass of methanol were charged. Stirring while heating, a retardation increasing agent solution (and a fine particle dispersion) was prepared. 25 parts by mass of the retardation increasing agent solution was mixed with 474 parts by mass of the cellulose acetate solution, and the dope was prepared by sufficiently stirring, and was manufactured in the same manner as in the first retardation region 1 except that the draw ratio was 23%. Filmed. The film thus obtained (first retardation region 3) had a thickness of 80 μm. About the produced 1st phase difference area | region 3, Re is 35 nm by measuring the light incident angle dependence of Re using an automatic birefringence meter (KOBRA-21ADH, Oji Scientific Instruments Co., Ltd. product). It was found that Rth was 135 nm and Nz was 4.4.

<Production of second retardation regions 1 to 6>
The surfaces of the manufactured first retardation region 1, first retardation region 2, and first retardation region 3 are subjected to saponification treatment, and 20 ml of an alignment film coating solution having the following composition is applied to the film using a wire bar coater. / M ^{2 was} applied. The film was formed by drying with warm air of 60 ° C. for 60 seconds and further with warm air of 100 ° C. for 120 seconds. Next, the formed film was rubbed in a direction parallel to the slow axis direction of the film to obtain an alignment film.
Composition of alignment film coating solution Modified polyvinyl alcohol 10 parts by weight Water 371 parts by weight Methanol 119 parts by weight Glutaraldehyde 0.5 parts by weight

  Next, 3.8 g of the following rod-like liquid crystal compound, 0.152 g of a photopolymerization initiator (Irgacure 819, manufactured by Ciba Specialty Chemicals Co., Ltd.), 0.038 g of the following chain transfer agent, 0.011 g of the following onium salt The following solutions were prepared by dissolving 0.002 g of the following air interface side vertical alignment agent in 16.4 g of 1,1,2-trichloroethane (No. 2-1 to 2-7 coating solutions shown in Table 1). . This coating solution was applied to the surface of the alignment film with a wire bar having the count shown in Table 2. This was affixed to a metal frame, heated in a thermostatic bath at 135 ° C. for 1 minute, then cooled to 115 ° C. and oriented. After heating at 115 ° C. for 30 seconds, the alignment was fixed by UV irradiation with a 120 W / cm high-pressure mercury lamp for 15 seconds, and then allowed to cool to room temperature to form a retardation layer. The rod-like liquid crystalline compounds V-11 and V-12 became isotropic at 135 ° C. and formed a smectic phase at 115 ° C.

A transparent and uniform film could be formed with the retardations 1 to 6, but the retardation 7 was scattered and was not suitable as a retardation film for a liquid crystal display device. Next, the alignment state was observed under a polarizing microscope for phase differences 1 to 6.
The phase difference 1 to 3 had no bright spots and was completely dark field, but the phase difference 4 to 6 had many bright spots. Next, the optical characteristics of the phase differences 1 to 6 were examined. Specifically, using an automatic birefringence meter (KOBRA-21ADH, manufactured by Oji Scientific Instruments Co., Ltd.), the dependence of Re on the light incident angle of the manufactured film was measured, and the contribution of the support measured in advance When the optical characteristics of only the second phase difference region were calculated by subtracting the minute, Re was 0 nm and Rth was −225 nm for the second phase difference region 1, and Re was 0 nm and Rth for the second phase difference region 2, respectively. -180 nm, second retardation region 3 has Re 0 nm, Rth is -295 nm, second retardation region 4 has Re 0 nm, Rth is -170 nm, second retardation region 5 has Re 0 nm, Rth is -292 nm In the second retardation region 6, Re was 0 nm and Rth was −290 nm, and it was confirmed that the rod-like liquid crystal was aligned substantially vertically. Further, in any optically anisotropic film, it was confirmed by X-ray analysis that rod-like liquid crystalline molecules were fixed in a smectic phase alignment state. When the mole light in front of the second phase difference regions 1 to 3 was measured, it was 0.1% or less in all cases, but in the second phase difference regions 4 to 6, it was 1 to 2%.

<Production of Polarizing Plate Protective Film 1>
The following composition was put into a mixing tank, stirred while heating to dissolve each component, and a cellulose acetate solution A was prepared.
<Composition of cellulose acetate solution A>
Cellulose acetate with a substitution degree of 2.86 100 parts by weight Triphenyl phosphate (plasticizer) 7.8 parts by weight Biphenyl diphenyl phosphate (plasticizer) 3.9 parts by weight Methylene chloride (first solvent) 300 parts by weight Methanol (second solvent) 54 parts by weight 1-butanol 11 parts by weight

The following composition was charged into another mixing tank, stirred while heating to dissolve each component, and an additive solution B-1 was prepared.
<Additive solution B-1 composition>
Methylene chloride 80 parts by mass Methanol 20 parts by mass The following optical anisotropy reducing agent 40 parts by mass

40 parts by mass of the additive solution B-1 was added to 477 parts by mass of the cellulose acetate solution A, and the dope was prepared by sufficiently stirring. The dope was cast from a casting port onto a drum cooled to 0 ° C. The film is peeled off at a solvent content of 70% by mass, and both ends in the width direction of the film are fixed with a pin tenter (the pin tenter described in FIG. 3 of JP-A-4-1009), and the solvent content is 3-5% by mass. In this state, the film was dried while maintaining an interval at which the stretching ratio in the transverse direction (direction perpendicular to the machine direction) was 3%. Then, it further dried by conveying between the rolls of the heat processing apparatus, and produced the polarizing plate protective film 1 with a thickness of 80 μm.
Using an automatic birefringence meter (KOBRA-21ADH, manufactured by Oji Scientific Instruments Co., Ltd.), the light incident angle dependence of Re was measured, and the optical characteristics were calculated. Re was 1 nm and Rth was 6 nm. I was able to confirm.

<Preparation of polarizing plate A>
Next, iodine is adsorbed on the stretched polyvinyl alcohol film to produce a polarizing film, and a commercially available cellulose acetate film (Fujitac TD80UF, manufactured by Fuji Photo Film Co., Ltd., Re = 3 nm, Rth = 45 nm) is subjected to saponification treatment. A polarizing plate A was formed on one surface of the polarizing film using a polyvinyl alcohol adhesive.

<Preparation of polarizing plate B>
A polarizing film is produced by adsorbing iodine to a stretched polyvinyl alcohol film, and a commercially available cellulose acetate film (Fujitac TD80UF, manufactured by Fuji Photo Film Co., Ltd.) is subjected to saponification treatment, using a polyvinyl alcohol adhesive, A polarizing plate B was formed on both sides of the polarizing film.

<Preparation of polarizing plate C>
A polarizing film was produced in the same manner, and a commercially available cellulose acetate film (Fujitac TD80UF, manufactured by Fuji Photo Film Co., Ltd.) was saponified and attached to one side of the polarizing film using a polyvinyl alcohol-based adhesive. . In the same manner, the polarizing plate protective film 1 manufactured as described above was attached to the other side of the polarizing film to form a polarizing plate C.

<Preparation of polarizing plate D>
A polarizing film was produced in the same manner, and a commercially available cellulose acetate film (Fujitac TD80UF, manufactured by Fuji Photo Film Co., Ltd.) was saponified and attached to one side of the polarizing film using a polyvinyl alcohol-based adhesive. . In the same manner, a commercially available cellulose acetate film (Fujitac T40UZ, manufactured by Fuji Photo Film Co., Ltd., Re = 1 nm, Rth = 35 nm) was saponified, and the other side of the polarizing film was coated with a polyvinyl alcohol adhesive. A pasting polarizing plate D was formed.

<Preparation of polarizing plate E>
In the polarizing plate C, a polarizing plate E was formed using ZEONOR ZF14 (manufactured by Zeon Corporation, Re = 5 nm, Rth = 5 nm) instead of the polarizing plate protective film 1.

[Example 1]
Using a polyvinyl alcohol-based adhesive for the polarizing plate A, the produced film retardation 1 is formed so that the first retardation region 1 side is the polarizing film side and the transmission axis of the polarizing film and the first retardation region 1 A polarizing plate 1 was formed on the side of the polarizing film where the cellulose acetate film was not bonded so that the slow axis was parallel.

This is applied to one of the IPS mode liquid crystal cells 1 produced above so that the slow axis of the first retardation region 1 is parallel to the rubbing direction of the liquid crystal cell (that is, the slow phase of the first retardation region 1). The polarizing plate 1 was affixed so that the axis was parallel to the slow axis of the liquid crystal molecules of the liquid crystal cell during black display) and the second retardation region 1 surface side was on the liquid crystal cell side.
Subsequently, the polarizing plate C is attached to the other side of the IPS mode liquid crystal cell 1 so that the polarizing plate protective film 1 side is on the liquid crystal cell side, and in a crossed Nicol arrangement with the polarizing plate 1. A liquid crystal display device was produced. The leakage light of the liquid crystal display device thus manufactured was measured. The leakage light when observed from the left oblique direction of 60 ° was 0.04%.

[Example 2]
Using a polyvinyl alcohol-based adhesive for the polarizing plate A, the produced film retardation 2 is formed so that the first retardation region 1 side is the polarizing film side and the transmission axis of the polarizing film and the first retardation region 1 A polarizing plate 2 was formed on the side of the polarizing film where the cellulose acetate film was not bonded so that the slow axis was parallel.

This is applied to one of the IPS mode liquid crystal cells 1 produced above so that the slow axis of the first retardation region 1 is parallel to the rubbing direction of the liquid crystal cell (that is, the slow phase of the first retardation region 1). The polarizing plate 2 was attached so that the axis was parallel to the slow axis of the liquid crystal molecules of the liquid crystal cell during black display) and the second phase difference region 2 surface side was on the liquid crystal cell side.
Subsequently, the polarizing plate D is attached to the other side of the IPS mode liquid crystal cell 1 so that the T40UZ side is the liquid crystal cell side and the polarizing plate 2 is in a crossed Nicol arrangement, and the liquid crystal display device is attached. Produced. The leakage light of the liquid crystal display device thus manufactured was measured. The leakage light when observed from the left oblique direction of 60 ° was 0.05%.

[Example 3]
Acrylic resin so that the film retardation 3 is applied to the polarizing plate B, the second retardation region 3 side is the polarizing film side, and the transmission axis of the polarizing film and the slow axis of the first retardation region 2 are orthogonal to each other. The sticking polarizing plate 3 was formed using a system adhesive.

This is applied to one of the IPS mode liquid crystal cells 1 produced above so that the slow axis of the first retardation region 2 is orthogonal to the rubbing direction of the liquid crystal cell (that is, the slow phase of the first retardation region 2). The polarizing plate 3 was attached so that the axis was perpendicular to the slow axis of the liquid crystal molecules of the liquid crystal cell during black display) and the first retardation region 2 surface side was on the liquid crystal cell side.
Subsequently, the polarizing plate C is attached to the other side of the IPS mode liquid crystal cell 1 so that the polarizing plate protective film 1 side is on the liquid crystal cell side and the polarizing plate 3 is in a crossed Nicol arrangement, A liquid crystal display device was produced. The leakage light of the liquid crystal display device thus manufactured was measured. The leakage light when observed from the left oblique direction of 60 ° was 0.06%.

[Comparative Example 1]
Acrylic resin so that the film retardation 4 is applied to the polarizing plate C, the second retardation region 4 side is on the polarizing film side, and the transmission axis of the polarizing film and the slow axis of the first retardation region 1 are orthogonal to each other. A polarizing plate 4 was formed on the polarizing plate protective film 1 side using a system adhesive.

This is applied to one of the IPS mode liquid crystal cells 1 produced above so that the slow axis of the first retardation region 1 is orthogonal to the rubbing direction of the liquid crystal cell (that is, the slow phase of the first retardation region 1). The polarizing plate 4 was attached so that the axis was perpendicular to the slow axis of the liquid crystal molecules of the liquid crystal cell during black display) and the first phase difference region 1 surface side was the liquid crystal cell side.
Subsequently, a polarizing plate B was attached to the other side of the IPS mode liquid crystal cell 1 so as to be in a crossed Nicols arrangement with respect to the polarizing plate 4 to produce a liquid crystal display device. The leakage light of the liquid crystal display device thus manufactured was measured. The leakage light when observed from the left oblique direction of 60 ° was 1.2%.

[Comparative Example 2]
Acrylic resin system in which the film retardation 5 is applied to the polarizing plate E so that the second retardation region 6 side is the polarizing film side, and the transmission axis of the polarizing film and the slow axis of the first phase region 1 are orthogonal to each other. Using an adhesive, the polarizing plate 5 was formed by being attached to the ZEONOR side.
A liquid crystal display device was produced in the same manner as in Example 3 and measured for more light. The mole light when observed from the left oblique direction of 60 ° was 1.4%.

[Comparative Example 3]
Acrylic resin system in which the film retardation 6 is applied to the polarizing plate E, the second retardation region 6 side is on the polarizing film side, and the transmission axis of the polarizing film and the slow axis of the first phase region 1 are orthogonal to each other. A polarizing plate 6 was formed by sticking to the ZEONOR side using an adhesive.
A liquid crystal display device was produced in the same manner as in Example 3 and measured for more light. The mole light when observed from the left oblique direction of 60 ° was 2.2%.
[Example 4]
The first retardation region 3 was bonded to the polarizing plate A using a polyvinyl alcohol-based adhesive so that the slow axis was parallel to the transmission axis of the polarizing film. Next, in the first retardation region 3 attached to the polarizing plate A, the film retardation 3 is set to the first retardation region 3 side to which the first retardation region 3 is attached, and the polarizing plate A A polarizing plate 7 was formed by attaching an acrylic resin adhesive so that the transmission axis of the polarizing film and the slow axis of the first retardation region 3 were parallel to each other. In this case, the first retardation region is formed of a stacked body in which two first retardation regions 3 (Re = 35 nm, Rth = 135 nm) are stacked, and Re = 70 nm, Rth = It has optical properties of 270 nm and Nz = 4.4.

This is applied to one of the IPS mode liquid crystal cells 1 produced above so that the slow axis of the first retardation region 3 is parallel to the rubbing direction of the liquid crystal cell (that is, the slow phase of the first retardation region 3). The polarizing plate 5 was attached so that the axis was parallel to the slow axis of the liquid crystal molecules of the liquid crystal cell during black display) and the second retardation region 3 surface side was on the liquid crystal cell side.
Subsequently, the polarizing plate D is attached to the other side of the IPS mode liquid crystal cell 1 so that the T40UZ side is the liquid crystal cell side and the polarizing plate 2 is in a crossed Nicol arrangement, and the liquid crystal display device is attached. Produced. The leakage light of the liquid crystal display device thus manufactured was measured. The leakage light when observed from the left oblique direction of 60 ° was 0.13%.

[Comparative Example 4]
A commercially available polarizing plate (HLC2-5618, manufactured by Sanritz Co., Ltd.) was attached to both sides of the produced IPS mode liquid crystal cell 1 in a crossed Nicol arrangement to produce a liquid crystal display device. An optical compensation film was not used. In the liquid crystal display device, as in Example 1, the polarizing plate was attached so that the transmission axis of the upper polarizing plate was parallel to the rubbing direction of the liquid crystal cell. The leakage light of the liquid crystal display device thus manufactured was measured. The leakage light when observed from the left oblique direction of 60 ° was 0.62%.

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

Explanation of symbols

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

Claims (11)

Optical anisotropy formed from a composition containing at least one liquid crystalline compound exhibiting a smectic phase on an alignment film and an additive having chain transfer ability, and the liquid crystalline compound is fixed in an aligned state Sex membrane. The composition comprises at least one additive that promotes vertical alignment of the liquid crystalline compound at the air interface and / or at least one additive that promotes vertical alignment of the liquid crystalline compound at the alignment film interface. The optically anisotropic film according to claim 1, wherein the optically anisotropic film is contained and fixed in a state in which the liquid crystalline compound is vertically aligned. The optically anisotropic film according to claim 1, wherein the alignment film is a polyvinyl alcohol polymer. The optically anisotropic film according to any one of claims 1 to 3, wherein the composition contains at least one additive that promotes vertical alignment of the liquid crystalline compound at the alignment film interface. At least one liquid crystalline compound exhibiting a smectic phase, at least one additive that promotes vertical alignment of the liquid crystalline compound at the air interface, and / or the liquid crystal compound is vertically aligned at the alignment film interface. An optical system in which a composition containing at least one additive for promoting is applied on an alignment film, heat-treated at a temperature equal to or higher than the transition temperature of the liquid crystal phase or isotropic phase of the liquid crystalline compound, and then cooled and fixed A method for producing an anisotropic film. Including at least a first polarizing film, a first retardation region, a second retardation region, and a liquid crystal cell having a liquid crystal layer sandwiched between a pair of substrates, and liquid crystal molecules are placed on the surfaces of the pair of substrates during black display. A liquid crystal display device oriented substantially parallel to the
The retardation Re (λ) at the wavelength λ nm of the first retardation region is 20 nm to 150 nm, and the in-plane refractive indexes nx and ny (nx> ny) and the refractive index nz in the thickness direction are used to obtain Nz = The Nz value of the first phase difference region defined by (nx−nz) / (nx−ny) is 1.5 to 7,
The in-plane refractive indexes nx and ny of the second retardation region are substantially equal, nx <nz, and the retardation Rth (λ) in the thickness direction at the wavelength λnm of the second retardation region is −80 nm to −400 nm. And the second retardation region includes the optically anisotropic film according to any one of claims 1 to 4, and the transmission axis of the first polarizing film is a slow axis direction of liquid crystal molecules during black display. Liquid crystal display device that is parallel to. The first polarizing film, the first retardation region, the second retardation region, and the liquid crystal cell are arranged in this order, and the slow axis of the first retardation region is the same as that of the first polarizing film. The liquid crystal display device according to claim 6, which is substantially parallel to the transmission axis. The first polarizing film, the second retardation region, the first retardation region, and the liquid crystal cell are arranged in this order, and the slow axis of the first retardation region is the transmission axis of the first polarizing film. The liquid crystal display device according to claim 6, which is substantially orthogonal to. And a second polarizing film having a transmission axis orthogonal to the transmission axis of the first polarizing film, wherein the first and second polarizing films are the first retardation region, the second retardation region, and the liquid crystal. The liquid crystal display device according to claim 6, wherein the liquid crystal display device is disposed with a cell interposed therebetween. It has a pair of protective films arranged with the first polarizing film and / or the second polarizing film in between, and the thickness direction retardation Rth of the protective film closer to the liquid crystal layer of the pair of protective films is 40 nm. The liquid crystal display device according to claim 6, wherein: A pair of protective films disposed between the first polarizing film and / or the second polarizing film, wherein the protective film on the side close to the liquid crystal layer is a cellulose acylate film or a norbornene film; The liquid crystal display device according to any one of claims 6 to 10.

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