WO2006011647A1 - Polymerizable composition, optically anisotropic layer and method for manufacturing thereof, optical compensatory element, liquid crystal display and liquid crystal projector - Google Patents

Polymerizable composition, optically anisotropic layer and method for manufacturing thereof, optical compensatory element, liquid crystal display and liquid crystal projector Download PDF

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Publication number
WO2006011647A1
WO2006011647A1 PCT/JP2005/014161 JP2005014161W WO2006011647A1 WO 2006011647 A1 WO2006011647 A1 WO 2006011647A1 JP 2005014161 W JP2005014161 W JP 2005014161W WO 2006011647 A1 WO2006011647 A1 WO 2006011647A1
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Prior art keywords
liquid crystal
optically anisotropic
compound
anisotropic layer
layer
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PCT/JP2005/014161
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French (fr)
Inventor
Shintaro Washizu
Yosuke Takeuchi
Kenichi Nakagawa
Masao Sato
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Fujifilm Corporation
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Publication of WO2006011647A1 publication Critical patent/WO2006011647A1/en

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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K19/00—Liquid crystal materials
    • C09K19/04—Liquid crystal materials characterised by the chemical structure of the liquid crystal components, e.g. by a specific unit
    • C09K19/06—Non-steroidal liquid crystal compounds
    • C09K19/32—Non-steroidal liquid crystal compounds containing condensed ring systems, i.e. fused, bridged or spiro ring systems
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K19/00—Liquid crystal materials
    • C09K19/04—Liquid crystal materials characterised by the chemical structure of the liquid crystal components, e.g. by a specific unit
    • C09K19/38—Polymers
    • C09K19/3833—Polymers with mesogenic groups in the side chain
    • C09K19/3842—Polyvinyl derivatives
    • C09K19/3852—Poly(meth)acrylate derivatives
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K19/00—Liquid crystal materials
    • C09K19/52—Liquid crystal materials characterised by components which are not liquid crystals, e.g. additives with special physical aspect: solvents, solid particles
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/13363—Birefringent elements, e.g. for optical compensation
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F222/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a carboxyl radical and containing at least one other carboxyl radical in the molecule; Salts, anhydrides, esters, amides, imides, or nitriles thereof
    • C08F222/10—Esters
    • C08F222/1006—Esters of polyhydric alcohols or polyhydric phenols
    • C08F222/103—Esters of polyhydric alcohols or polyhydric phenols of trialcohols, e.g. trimethylolpropane tri(meth)acrylate
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K19/00—Liquid crystal materials
    • C09K19/04—Liquid crystal materials characterised by the chemical structure of the liquid crystal components, e.g. by a specific unit
    • C09K2019/0425—Liquid crystal materials characterised by the chemical structure of the liquid crystal components, e.g. by a specific unit characterized by a specific unit that results in a functional effect
    • C09K2019/0429—Liquid crystal materials characterised by the chemical structure of the liquid crystal components, e.g. by a specific unit characterized by a specific unit that results in a functional effect the specific unit being a carbocyclic or heterocyclic discotic unit
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K19/00—Liquid crystal materials
    • C09K19/04—Liquid crystal materials characterised by the chemical structure of the liquid crystal components, e.g. by a specific unit
    • C09K2019/0444—Liquid crystal materials characterised by the chemical structure of the liquid crystal components, e.g. by a specific unit characterized by a linking chain between rings or ring systems, a bridging chain between extensive mesogenic moieties or an end chain group
    • C09K2019/0448—Liquid crystal materials characterised by the chemical structure of the liquid crystal components, e.g. by a specific unit characterized by a linking chain between rings or ring systems, a bridging chain between extensive mesogenic moieties or an end chain group the end chain group being a polymerizable end group, e.g. -Sp-P or acrylate
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F2202/00—Materials and properties
    • G02F2202/02—Materials and properties organic material
    • G02F2202/022—Materials and properties organic material polymeric
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F2413/00—Indexing scheme related to G02F1/13363, i.e. to birefringent elements, e.g. for optical compensation, characterised by the number, position, orientation or value of the compensation plates
    • G02F2413/04—Number of plates greater than or equal to 4

Definitions

  • the present invention relates to a polymerizable composition, an optically anisotropic layer suitably used for optical compensatory elements or the like and a method for manufacturing the polymerizable composition and the optically anisotropic layer.
  • the present invention further relates to an optical compensatory element, a liquid crystal display, and a liquid crystal projector. Description of the Related Art
  • the optically anisotropic layer of the present invention comprises the polymerizable composition according to the present invention, which enables producing an optically anisotropic layer having a uniform thickness, obtaining the desired optical properties in the optically anisotropic layer with high precision, and preventing light leakage at a wide range of viewing angles.
  • FIG. 3 is a sectional view showing an example of the optical compensatory element according to a third configuration of the present invention.
  • FIG. 4 is a sectional view showing an example of the optical compensatory element according to a fourth configuration of the present invention.
  • FIG. 7 is a sectional view showing an example of the optical compensatory element according to a seventh configuration of the present invention.
  • FIG. 11 is a schematic view showing still another example of the liquid crystal display according to the present invention.
  • FIG. 12 is a schematic view showing a still more example of the liquid crystal display according to the present invention.
  • the polymerizable composition according to the present invention comprises a polymerizable liquid crystal compound and a solvent whose boiling point is relatively high and further comprises other components suitably selected in accordance with the intended use.
  • - Polymerizable liquid crystal compound -
  • the polymerizable liquid crystal compound is not particularly limited and may be suitably selected in accordance with the intended use, provided that the compound has a functional group capable of being polymerized or cross-linked with a compound which can be formed in a direction of alignment.
  • the polymerizable liquid crystal compound for example, is preferably a polymerizable liquid crystal compound comprising a liquid crystal compound whose alignment can be fixed, is more preferably a rod-shaped, discotic or banana-shaped liquid crystal compound and is still more preferably a discotic liquid crystal compound.
  • the polymerizable liquid crystal compound may further comprise any other components suitably selected in accordance with the intended use.
  • the polymerizable liquid crystal compound comprising a rod-shaped liquid crystal compound is not particularly limited and may be suitably selected in accordance with the intended use.
  • Examples of the polymerizable liquid crystal compound comprising a rod-shaped liquid crystal compound are polymeric liquid crystal compounds formed by polymerization of a rod-shaped liquid crystal compound represented by the following Structural Formula (1) and having low-molecular polymerizable groups.
  • the polymerizable liquid crystal compound comprising a discotic liquid crystal compound is not particularly limited and may be suitably selected in accordance with the intended use.
  • examples thereof include a polymerizable liquid crystal compound capable of fixing the alignment of the discotic liquid crystal compound through the use of a polymer binder, and a polymerizable liquid crystal compound having a polymerizable group capable of fixing the alignment of the discotic liquid crystal compound as a result of polymerization.
  • the polymerizable liquid crystal compound having the polymerizable group is preferred.
  • alkoxy-substituted alkyl carboxylic acid alkyl ester compound examples include 0-methyl lactate methyl, 0-ethyl lactate ethyl, 0-methyl lactate butyl, methyl 2-ethoxy propionate, ethyl 2-ethoxy propionate, ethyl 3-ethoxyl propionate, ethyl 3-methoxy butanoic acid, ethyl 3-ethoxy butanoic acid, ethyl 4-methoxy butanoic acid, methyl 2-methoxy pentanoic acid, methyl 2-ethoxy pentanoic acid, methyl 2-methoxy propionate, and methyl 3-methoxy propionate.
  • the respective contents of the alkoxy-substituted alkyl carboxylic acid alkyl ester compound (C), the hydroxy carboxylic acid alkyl ester compound (B) and the alkoxy alkyl acetate compound are individually less than 200 parts by mass relative to 100 parts by mass of the polymerizable liquid crystal compound, coating property becomes degraded and may result in unevenness in film thickness.
  • the respective contents thereof are individually more than 1,000 parts by mass, the individual evaporation rates of the alkoxy-substituted alkyl carboxylic acid alkyl ester compound (C), the hydroxy carboxylic alkyl ester compound (B), and the alkoxy alkyl acetate compound are delayed and may result in unevenness in film thickness.
  • the optical compensatory film makes it possible to arbitrarily combine the phase difference of light passing through a liquid crystal layer with respect to each colors of red color, green color, and blue color in a liquid crystal display and the phase difference of the optical compensatory film to optically compensate the liquid crystal layer under a condition for displaying black three-dimensionally, with respect to each colors of red, green and blue and .prevent light leakage when viewed from any direction to eliminate issues of viewing angle dependency.
  • the polymerizable liquid crystal compound in the polymerizable composition is preferably aligned (in alignment) immediately before a polymerization reaction in forming the optically anisotropic layer, and the alignment (the state of alignment) is not particularly limited and may be suitably selected in accordance with the intended use.
  • the polymerizable liquid crystal compound may be fixed in its structure by a polymerization or a cross-linking to thereby show no liquid crystal appearance in the optically anisotropic layer.
  • the reactive group is not particularly limited and may be suitably selected in accordance with the intended use.
  • a reactive group may be selected in accordance with the intended use.
  • a reactive group may be introduced into a side chain of a repeating unit of the polymer for an alignment layer, or a cyclic group as a substituent may be introduced into the polymer for an alignment layer.
  • the materials of the structurally birefringent layer are not particularly limited, may be suitably selected in accordance with the intended use and include, for example, various organic materials and inorganic materials.
  • the material for the multilayered film constituting one repeating unit which constitutes the structurally birefringent layer is not particularly limited, may be suitably selected in accordance with the intended use, preferably has a combination of plural materials suitably selected from oxide layers, and more preferably has a combination of a SiCh layer and a ⁇ O2 layer.
  • the number of layers of the multilayered film of the structurally birefringent layer is not particularly limited and may be suitably selected in accordance with the intended use.
  • the support itself may have them.
  • a material like an elongated cellulose triacetate, is used as the support and only retardation fulfills the functions, the structurally birefringent layer may not be formed.
  • an optically isotropic material like glass, it is possible to use the structurally birefringent layer suitably.
  • the thickness of an optical anisotropic layer made from a material other than the material having birefringence in structure may be suitably determined in the light of functions as a protective film and a support, when the layer comprises the protective film layer and the support.
  • functions as an antireflective layer can be given by suitably selecting configurations of each layer from the viewpoint of an optical thickness of layers.
  • the antireflective layer as the material constituting a layer having different refractive indices, not only inorganic materials but also organic materials and a material with organic materials to which inorganic materials are added can be used, as long as the conditions of configurations for the optical thickness of layer are satisfied.
  • the protective layer is not particularly limited, may be selected in accordance with the intended use, and includes cellulose esters such as cellulose acetate, cellulose acetate butylate, and cellulose propionate; polycarbonate, polyolefin, polystyrene, and polyester.
  • the retardation of the protective layer is not particularly limited, maybe suitably selected in accordance with the intended use and is preferably, for example, lOnm or less and more preferably 5nm or less when measured by light having wavelength of 632.8nm.
  • a layer serving to both the additional optical anisotropic layer and a protective layer can be formed by using a film controlled to a desired retardation value.
  • the optical compensatory element 10 further comprises first optically anisotropic layer 2 and antireflective layer 5 A arranged in this order on the opposite surface of the support 1 so that the antireflective layer 5A constitutes another outermost surface.
  • the first optically anisotropic layer 2 has an alternatively multilayered structure comprising a TiO 2 layer 2 A and a SiO 2 layer 2B. The thickness of the respective layers is about 15nm.
  • the first optically anisotropic layer 2 can also serve as an antireflective layer by having such an alternatively multilayered structure.
  • the rubbing directions of the alignment layer 4 A and the alignment layer 4B preferably differ from each other by 90 degrees.
  • optical compensatory element having the respective layers arranged on one surface of the support, as in the optical compensatory element 20 according to the second configuration, can be generally satisfactorily handled and easily prepared, while these properties depend on the materials of the respective layers and combinations thereof.
  • optical compensatory element 30 comprises first optically anisotropic layer 32, alignment layer
  • the first optically anisotropic layer 32 can have a similar structure to that of the first optically anisotropic layer 2 in the optical compensatory element 10 according to the first configuration.
  • the first optically anisotropic layer 42 can have a similar structure to that of the first optically anisotropic layer 2 in the optical compensatory element 10 according to the first configuration.
  • optical compensatory element 60 comprises two second optically anisotropic layers having different direction of alignments.
  • optical compensatory element 60 according to the sixth configuration comprises alignment layer 64A, second optically anisotropic layer 63A, alignment layer 64B, second optically anisotropic layer 63B, first optically anisotropic layer 62, and antireflective layer 65B arranged in this order on one surface of support 61, so that the antireflective layer 65B constitutes an outermost layer, and comprises antireflective layer 65A on the opposite surface of the support 61.
  • FIG. 7 is a sectional view schematically showing an optical compensatory element according to the seventh configuration of the present invention.
  • the first optically anisotropic layer 82 can have a similar structure to that of the first optically anisotropic layer 2 in the optical compensatory element 10 according to the first configuration.
  • Two plies of the optical compensatory element 80 according to the eight configuration can be used as a laminate.
  • rubbing directions of the alignment layers in the respective optical compensatory elements preferably differ from each other by 90 degrees.
  • An optical thickness of the repeating unit i.e., a thickness of a repeating unit in a laminating direction of the alternatively multilayered structure is preferred to be formed less than the wavelengths of light in the visible region.
  • the wavelengths of light in the visible region is ⁇ , it is preferably ⁇ /100 to ⁇ /5, more preferably ⁇ /50 to ⁇ /5, and particularly preferably ⁇ /30 to ⁇ /10.
  • the preferred examples of the polymer for an alignment layer for aligning the liquid crystal compound in a direction perpendicular to the direction of rubbing are modified polyvinyl alcohols, acrylic copolymers, polyimides, and polyamic acid. Polyimides which are excellent in alignment properties are more preferred.
  • the thickness of the alignment layer is not particularly limited, may be suitably selected in accordance with the intended use, is preferably O.Ol ⁇ m to 5 ⁇ m, and more preferably 0.02 ⁇ m to 2 ⁇ m.
  • an optically anisotropic layer using at least a polymerizable liquid crystal composition is formed on the alignment layer.
  • a second optically anisotropic layer is heated to form the alignment uniformly and mature the alignment to be maintained.
  • the coated layer is heated at 60°C to 120 0 C to volatilize and dry the solvent.
  • the active rays for photopolymerization can be suitably selected from electron beam, ultraviolet rays, visible beam, infrared rays (heat rays), in accordance with the intended use. Typically, ultraviolet rays are preferred. Examples of the light source for ultraviolet rays include low pressure mercury lamps (bactericidal lamp, fluorescent chemical lamp, and blacklight lamp), high voltage discharge lamps
  • the coating is not particularly limited, can be coated by any procedure in accordance with the intended use, and the antireflective layer is formed by, for example, a wire bar coating, a gravure coating, a micro gravure coating, and a dye coating. From the perspective of reducing uneven dryness by minimizing the coated amount of a wet solution, a micro gravure coating and a gravure coating are preferred, while from the perspective of uniform thickness in a lateral direction and uniform thickness in a longitudinal direction with time since the coating, a rotating gravure coating is more preferred.
  • the coating method is not particularly limited and includes, for example, an extrusion coating, a direct gravure coating, a reverse gravure coating, a dye coating, and a spin-coating.
  • the displaying mode of the liquid crystal device is not particularly limited, may be suitably selected in accordance with the intended use, and includes, for example, TN (Twisted Nematic) mode, VA (Vertical Alignment) mode, IPS (In-Plane Switching) mode, OCB (Optically Compensatory Bend) mode, and ECB (Electrically Controlled Birefringence) mode.
  • TN mode is particularly preferable because of its high contrast ratio.
  • FIGs. 9 to 12 are respectively schematic diagrams showing the liquid crystal displays of the present invention.
  • liquid crystal display 100 comprises upper polarizing element 101 (analyzer) and lower polarizing element 116 (polarizer) which are a pair of polarizing elements, wave plate 108 arranged between the upper and lower polarizing elements 101 and 116 and liquid crystal device 114 (liquid crystal cell).
  • the polarizing film is not particularly limited, may be suitably selected in accordance with the intended use and includes, for example, a stretched film made from a hydrophilic polymer which has adsorbed a dichroic material and has been subjected to stretching for alignment.
  • a hydrophilic polymer examples include polyvinyl alcohols, partially formalized polyvinyl alcohols, and partially saponified products of ethylene-vinyl acetate copolymers.
  • the dichroic material are iodine and dichroic dyes such as azo dyes, anthraquinone dyes, and tetrazine dyes.
  • Non-birefringent optical resin materials described in JP-A No. 08-110402 and JP-A No. 11-293116 can be used herein.
  • the alignment axis (slow axis) of the protective layer is arranged in any direction but is preferably in parallel with the longitudinal direction for easy and convenient operation.
  • the angle formed between the slow axis (alignment, axis) of the protective layer and the adsorption axis (stretching axis) of the polarizing film is not particularly limited and may be suitably set in accordance with the target polarizing plate.
  • the slow axis (alignment axis) of the protective layer is in a direction substantially perpendicular to the adsorption axis (stretching axis) of the polarizing film.
  • the upper and lower polarizing elements 101 and 116 preferably have optical properties and durability (short-term and long-time storage stability) equal to or higher than those of a commercially available high-contrast product, such as HLC2-5618 manufactured by Sanritz Corporation.
  • the optical compensatory element 108 comprises the optical compensatory element according to the present invention.
  • the maximum transmittance in displaying black is preferably 10% or less, and more preferably 5% or less of Vw in an azimuth direction inclined 60 degrees from the normal direction to the display surface of the liquid crystal display 100.
  • the liquid crystal display preferably does not optically quench in any direction and has an optical transmittance of 0.01% or more in all directions when the optical compensatory element is arranged between a pair of polarizing elements arranged in a cross nicol manner, and the optical compensatory element is rotated in the normal direction to the optical compensatory element as a rotation axis.
  • the directions of rubbing in the alignment layers in the second optically anisotropic layer and in the substrate of the liquid crystal device may be exchanged. More specifically, the layers may be arranged so that the angle formed between the direction of rubbing 106 of the alignment layer in the lower second optically anisotropic layer 105 and the direction of rubbing 110 of the upper alignment layer in the upper substrate 109 of the liquid crystal device 114 is 180° and so that the angle formed between the direction of rubbing 104 of the alignment layer in the upper second optically anisotropic layer 103 and ihe direction of rubbing 112 of the lower alignment layer in the lower substrate 113 of the liquid crystal device 114 is 180°.
  • the first optically anisotropic layer 107 is preferably arranged near to the liquid crystal device 114.
  • FIG. 11 schematically illustrates the arrangement of liquid crystal molecules in a liquid crystal display of a TN mode under a condition for displaying black , i.e., when a voltage is applied to the liquid crystal device 114.
  • the liquid crystal molecules change in their arrangement so that the liquid crystal molecules stand up with their major axes perpendicular to the incident plane of light.
  • all the liquid crystal molecules in the liquid crystal device 114 should preferably stand perpendicular to the incident plane of light upon application of a voltage.
  • nematic liquid crystal molecules for use in such a liquid crystal display of a TN mode are generally rod-shaped liquid crystal molecules and exhibit optically positive uniaxial properties. Accordingly, when the liquid crystal display 100 is viewed from an oblique direction, even the liquid crystal molecules at the center part of the liquid crystal device 114 stand up completely perpendicular to the incident direction of light cause birefringence, birefringence, and the liquid crystal device fails to display black and cause light leakage at some viewing angles.
  • the birefringence caused by the alignment of the liquid crystal molecules in the liquid crystal device 114 in the vicinity of the upper substrate 109 and of the lower substrate 113 under a condition for displaying black can be optically compensated by allowing the alignment of the liquid crystal molecules in the second optically anisotropic layers 103 and 105 to be mirror symmetry.
  • the birefringence caused by liquid crystal molecules at the center part of the liquid crystal device 114 can be optically compensated by arranging the first optically anisotropic layer 107 having optical properties as a not-inclined uniaxial ellipsoid having a negative refractive index.
  • the liquid crystal device 114 under a condition for displaying black can be optically compensated three-dimensionally in totality to thereby prevent light leakage in a wide range of viewing angles.
  • the optical compensate element 108 can be arranged under the liquid crystal device 114, as shown in FIG. 11, or can be arranged on or above any one of the light incident surface and the light output surface of the liquid crystal device 114 as optical compensate elements 108a and 108b, as shown in FIG. 12.
  • the optical compensate elements 108a and 108b are arranged on and under the optical crystal element 114, one of first optically anisotropic layers 107a and 107b can be omitted.
  • the retardation is defined as a total of the retardations of these layers.
  • the optical compensatory element 108 can have the upper substrate 109 and the lower substrate 113 of the liquid crystal device 114 as the substrate (not shown) equipped to the optical compensatory element 108.
  • the first optically anisotropic layers 107a and 107b shown in FIG. 12 are directly arranged on the upper substrate 109 and the lower substrate 113, respectively.
  • liquid crystal projector 200 comprises a diffusional transmittance screen 203 in front of housing 202.
  • An image projected to the rear of the screen 203 is viewed from the front of the screen 203.
  • Housing 202 houses a projection unit 300, and an image projected by the projection unit 300 is reflected by mirrors 206 and 207 to form an image on the rear side of the screen 203.
  • the projection unit 300 includes a liquid crystal display (not shown) as an image display device.
  • the liquid crystal display serves to display a reproduced image of the video signal to thereby display an image projected on the screen 203.
  • FIG. 14 is a schematic diagram illustrating a projection unit 300.
  • the projection unit 300 comprises three liquid crystal devices 311R, 311G, and 311B, and can project full-color images.
  • Light emitted from a light source 312 pass through a filter 313 for cutting ultraviolet rays and infrared rays, becomes white light including red light, green light, and blue light and comes into a glass rod 314 along an optical axis from the light source 312 to the liquid crystal devices 311R, 311G, and 311B.
  • the incident plane of light in the glass rod 314 is located in the vicinity of the focus of a parabolic mirror used in the light source 312, and the light from the light source 312 efficiently comes into the glass rod 314.
  • a relay lens 315 is arranged on a light output surface of the glass rod 314, and the white light going out from the glass rod 314 becomes parallel light by the action of the relay lens 315 and a subsequent collimate lens 316 and conies into a mirror 317.
  • the white light reflected by the mirror 317 is divided into two luminous fluxes by a dichroic mirror 318R transmitting red light alone, and the transmitted red light is reflected by a mirror 319 to illuminate a liquid crystal device 311R from the back.
  • the green light and the blue light reflected by the dichroic mirror 318R is further divided into two luminous fluxes by a dichroic mirror 318G reflecting green light alone.
  • the green light reflected by the dichroic mirror 318G illuminates a liquid crystal device 311G from the backside.
  • the blue light passing through the dichroic mirror 318G is reflected by mirrors 318B and 320 to illuminate a liquid crystal device 311B from the back.
  • the composite prism 324 internally includes two dichroic planes 324a and 324b and serves to composite the red light passing through the liquid crystal device 311R, the green light passing through the liquid crystal device 311G, and the blue light passing through the liquid crystal device 311B to allow the composite light to come into the projector lens 325.
  • the projector lens 325 is arranged on a projection light axis extending from the centers of light output surfaces of the liquid crystal devices 311R, 311G, and 311B via the centers of the composite prism 324 and the projector lens 325 to the centers of a screen 303.
  • the projector lens 325 is arranged so that its objective focal plane agrees with the light output surfaces of the liquid crystal devices 311R, 311G, and 311B, and its imaging focal plane agrees with the screen 303.
  • the full-color image composed by the composite prism 324 is allowed to form an image on the screen 303.
  • the illuminated red light reflected by the mirror 319 is converted into linearly polarized light by the action of the polarizing plate 326R near to the incident plate and comes into the liquid crystal device 311R.
  • a signal voltage is applied to a pixel to thereby allow a liquid crystal of a TN mode used in the liquid crystal device 311R to display black in a red image.
  • liquid crystal molecules in the liquid crystal layer have various postures in their alignment.
  • the image light modulated by the liquid crystal layer becomes elliptically polarized light having an optical phase slightly different from that of linearly polarized light. This causes light leakage from the polarizing plate 328R serving as the analyzer and fails to yield sufficient black level.
  • the liquid crystal projector of the present invention can thereby yield a high-quality image at a high contrast and a wide viewing angle.
  • Liquid crystal compound having a discotic structural unit represented by the following structural formula (3) 4.27g
  • a glass substrate was used as a support 1.
  • a first optically anisotropic layer having an alternately multilayered structure 2 was prepared by depositing layers of Si ⁇ 2 and TiO 2 in alternate manner on the glass substrate by vapor deposition using a sputtering machine under reduced pressure. Specifically, each twenty-six layers of SiOa and TiO 2 were formed, namely, a total of fifty-two layers were formed.
  • the resulting first optically anisotropic layer had a total thickness of 760nm and a retardation Rth of 200nm.
  • the obtained coating solution for an alignment layer was added dropwise in an amount of 100ml/ m 2 onto the opposite side of the glass substrate on which the first optically anisotropic layer formed and was subjected to spin coating at l,000rpm.
  • the coating solution for an alignment layer was then dried with a hot air at 100°C for three minutes to form an alignment layer 600nm having a thickness of 600nm.
  • the alignment layer was subjected to rubbing process to yield the alignment layer 4A aligned in a predetermined direction of alignment.
  • the discotic liquid crystal compound was hybrid aligned, since the angle (angle of alignment) formed by the normal line of the normal axis of the disc surface with the normal line of the glass substrate increases from 10° to 62° from the glass substrate toward the air interface side.
  • the angle of alignment of the discotic liquid crystal compound was determined by determining retardations at a varying observation angle using an ellipsometer (M-150, manufactured by JASCO Corporation), assuming a refractive index ellipsoid model based on the determined retardations and calculating the angle of alignment according to a technique described in "Design Concepts of the Discotic Negative Birefringence Compensation Films SID98 DIGEST".
  • the discotic liquid crystal compound was hybrid aligned, since the angle (angle of alignment) formed by the normal line of the normal axis of the disc surface with the normal line of the glass substrate increases from 7° to 60° from the glass substrate toward the air interface side.
  • the resultant second optically anisotropic layer 3B is homogenous layer without defects such as schlieren.
  • a liquid crystal display according to Example IA was prepared by laminating the above-prepared optical compensatory element 10 onto a liquid crystal device of a TN mode in a normally white mode at a voltage to display white of 1.5V and a voltage to display black of 3V.
  • the contrast of the above-prepared liquid crystal display was determined at a position with an angle of elevation of 60° and an azimuth angle of 30° from the front of the display surface using a conoscope (manufactured by Autronic-Melcher GmbH).
  • the contrast includes illuminance intensities in displaying white and in displaying black and a contrast ratio (illuminance intensity in displaying white/ illuminance intensity in displaying black) determined based on the ratio thereof.
  • Table 1 shows the results.
  • Example 2 With respect to the liquid crystal projector (according to Example 1B) > the illuminate intensities in displaying white and in displaying black/and the contrast ratio thereof (illuminate intensity in displaying white/ illuminate intensity in displaying black) on the screen set at a distance of 3m from the projector lens were determined. (Example 2)
  • Example 2 An optical compensatory element according to Example 2, a liquid crystal display according to Example 2A, and a liquid crystal projector according to Example 2B were prepared in the same manner as in Example 1, IA, and IB, respectively, provided that 15g of 2-(l-methoxypropyl) acetate (boiling point 145°C) included in the polymerizable composition in Example 1 was changed to 15g of
  • Example 3 An optical compensatory element according to Example 3, a liquid crystal display according to Example 3A, and a liquid crystal projector according to Example
  • Example 3B were prepared in the same manner as in Example 1, IA, and IB, respectively, provided that 15g of 2-(l-methoxypropyl) acetate (boiling point 145°C) included in the polymerizable composition in Example 1 was changed to 2Og of ethyl lactate
  • Example 4 An optical compensatory element according to Example 4, a liquid crystal display according to Example 4A, and a liquid crystal projector according to Example
  • An optical compensatory element according to Example 5, a liquid crystal display according to Example 5 A, and a liquid crystal projector according to Example 5B were prepared in the same manner as in Example 1, IA, and IB, respectively, provided that 15g of 2-(l-methoxypropyl) acetate (boiling point 145°C) included in the polymerizable composition in Example 1 was changed to 15g of 3-hyroxymethyl butanoic acid, and were evaluated.
  • Example 6 An optical compensatory element according to Example 6, a liquid crystal display according to Example 6A, and a liquid crystal projector according to Example 6B were prepared in the same manner as in Example 1, IA, and IB, respectively, provided that 15g of 2-(l-methoxypropyl) acetate (boiling point 145°C) included in the polymerizable composition in Example 1 was changed to 15g of butyl lactate (boiling point 186°C), and were evaluated. (Example 7)
  • Example 7 An optical compensatory element according to Example 7, a liquid crystal display according to Example 7A, and a liquid crystal projector according to Example 7B were prepared in the same manner as in Example 1, IA, and IB, respectively, provided that 15g of 2-(l-methoxypropyl) acetate (boiling point 145 0 C) included in the polymerizable composition in Example 1 was changed to 20.5g of 2-ethoxyethyl propionate, and were evaluated. (Example 8)
  • Example 8 An optical compensatory element according to Example 8, a liquid crystal display according to Example 8 A, and a liquid crystal projector according to Example 8B were prepared in the same manner as in Example 1, IA, and IB, respectively, provided that 15g of 2-(l-methoxypropyl) acetate (boiling point 145°C) included in the polymerizable composition in Example 1 was changed to 20.5g of 2-methoxymethyl propionate, and were evaluated. (Example 9)
  • Example 9 An optical compensatory element according to Example 9, a liquid crystal display according to Example 9A, and a liquid crystal projector according to Example 9B were prepared in the same manner as in Example 1, IA, and IB, respectively, provided that 15g of 2-(l-methoxypropyl) acetate (boiling point 145°C) included in the polymerizable composition in Example 1 was changed to 20.5g of 3-ethoxyethyl propionate (boiling PoIrItIOo 0 Q, and were evaluated. (Example 10)
  • An optical compensatory element according to Example 10 a liquid crystal display according to Example 1OA, and a liquid crystal projector according to Example 1OB were prepared in the same manner as in Example 1, IA, and IB, respectively, provided that 15g of 2-(l-methoxypropyl) acetate (boiling point 145°C) included in the polymerizable composition in Example 1 was changed to 20.5g of 3-methoxymethyl propionate (boiling point 142°C), and were evaluated.
  • Example 11 An optical compensatory element according to Example 11, a liquid crystal display according to Example HA, and a liquid crystal projector according to Example HB were prepared in the same manner as in Example 1, IA, and IB, respectively, provided that 15g of 2-(l-methoxypropyl) acetate (boiling point 145°C) included in the polymerizable composition in Example 1 was changed to a mixed solution of 16g of 3-ethoxyethyl propionate (boiling point 166°C) and 4g of ethyl lactate (boiling point 154°C), and were evaluated.
  • the viscosity of the polymerizable . composition at a temperature of 20°C is lOcP.
  • Example 12 An optical compensatory element according to Example 12, a liquid crystal display according to Example 12A, and a liquid crystal projector according to Example 12B were prepared in the same manner as in Example 1, IA, and IB, respectively, provided that 15g of 2-(l-methoxypropyl) acetate (boiling point 145°C) included in the polymerizable composition in Example 1 was changed to a mixed solution of 12g of 2-ethoxyethyl propionate (boiling point 166°C), 4g of ethyl lactate (boiling point 154 0 Q and 4g of methyl ethyl ketone (boiling point 8O 0 Q, and were evaluated.
  • the viscosity of the polymerizable composition at a temperature of 20°C is 7cP.
  • Example 13 An optical compensatory element according to Example 13, a liquid crystal display according to Example 13 A, and a liquid crystal projector according to Example 13B were prepared in the same manner as in Example 1, IA, and IB, respectively, provided that 15g of 2-(l-methoxypropyl) acetate (boiling point 145°C) included in the polymerizable composition in Example 1 was changed to a mixed solution of 12g of 3-ethoxyethyl propionate (boiling point 166°Q, 4g of hydroxyethyl butanoic acid and 4g of methyl ethyl ketone (boiling point 80°C), and were evaluated.
  • the viscosity of the polymerizable composition at a temperature of 20°C is 6cP.
  • Example 14 An optical compensatory element according to Example 14, a liquid crystal display according to Example 14A, and a liquid crystal projector according to Example 14B were prepared in the same manner as in Example 1, IA, and IB, respectively, provided that 15g of 2-(l-methoxy propyl) acetate (boiling point 145°C) included in the polymerizable composition in Example 1 was changed to a mixed solution of 12g of 3-ethoxyethyl propionate (boiling point 166°Q, 4g of butyl lactate (boiling point 186°C) and 4g of methyl ethyl ketone (boiling point 80°Q, and were evaluated.
  • the viscosity of the polymerizable composition at a temperature of 20°C is 6.5cP.
  • An optical compensatory element according to Example 15, a liquid crystal display according to Example 15A, and a liquid crystal projector according to Example 15B were prepared in the same manner as in Example 1, IA, and IB, respectively, provided that 15g of 2-(l-methoxypropyl) acetate (boiling point 145°C) included in the polymerizable composition in Example 1 was changed to a mixed solution of 12g of 3-ethoxyethyl propionate (boiling point 166 0 C), 4g of 3-hydroxymethyl butanoic acid and 2g of acetone, and were evaluated.
  • the viscosity of the polymerizable composition at a temperature of 20°C is 6cP.
  • Example 16 An optical compensatory element according to Example 16, a liquid crystal display according to Example 16A, and a liquid crystal projector according to Example 16B were prepared in the same manner as in Example 1, IA, and IB, respectively, provided that 15g of 2-(l-methoxypropyl) acetate (boiling point 145°C) included in the polymerizable composition in Example 1 was changed to a mixed solution of 12g of 3-ethoxyethyl propionate (boiling point 166°C), 4g of ethyl lactate and 4g of 2-(l-methoxypropyl) acetate (boiling point 145°C), and were evaluated.
  • the viscosity of the polymerizable composition at a temperature of 20°C is 6cP.
  • Example 17 An optical compensatory element according to Example 17, a liquid crystal display according to Example 17A, and a liquid crystal projector according to Example 17B were prepared in the same manner as in Example 1, IA, and IB, respectively, provided that 15g of 2-(l-methoxypropyl) acetate (boiling point 145°C) included in the polymerizable composition in Example 1 was changed to a mixed solution of 4g of 3-ethoxyethyl propionate (boiling point 166°C), 12g of ethyl lactate (boiling point 154°Q and 4g of 2-(l-methoxypropyl) acetate (boiling point 145°C), and were evaluated.
  • the viscosity of the polymerizable composition at a temperature of 20°C is 9.5cP.
  • Example 18 An optical compensatory element according to Example 18, a liquid crystal display according to Example 18 A, and a liquid crystal projector according to Example 18B were prepared in the same manner as in Example 1, IA, and IB, respectively, provided that 15g of 2-(l-methoxypropyl) acetate (boiling point 145°C) included in the polymerizable composition in Example 1 was changed to a mixed solution of 12g of 3-methoxymethyl propionate (boiling point 142°C), 4g of ethyl lactate (boiling point 154 0 Q and 4g of 2-(l-methoxypropyl) acetate (boiling point 145°C), and were evaluated.
  • the viscosity of the polymerizable composition at a temperature of 20°C is 8.4cP.
  • Example 20 An optical compensatory element according to Example 20, a liquid crystal display according to Example 20 A, and a liquid crystal projector according to Example 20B were prepared in the same manner as in Example 1, IA, and IB, respectively, provided that 15g of 2-(l-methoxypropyl) acetate (boiling point 145°C) included in the polymerizable composition in Example 1 was changed to a mixed solution of 12g of 3-ethoxyethyl propionate (boiling point 166°C),4g of butyl lactate (boiling point 186 0 Q and 4g of 2-(l-methoxypropyl) acetate (boiling point 145 0 C), and were evaluated.
  • the viscosity of the polymerizable composition at a temperature of 20 0 C is 8.6cP.
  • Example 21 An optical compensatory element according to Example 21, a liquid crystal 5 display according to Example 21 A, and a liquid crystal projector according to Example 21B were prepared in the same manner as in Example 1, IA, and IB, respectively, provided that 15g of 2-(l-methoxypropyl) acetate (boiling point 145°C) included in the polymerizable composition in Example 1 was changed to a mixed solution of 12g of 3-ethoxyethyl propionate (boiling point 166°C) and 8g of methyl ethyl o ketone (boiling point 80°C), and were evaluated.
  • the viscosity of the polymerizable composition at a temperature of 20 0 C is 5cP.
  • An optical compensatory element according to Comparative Example 1, a liquid crystal display according to Comparative Example IA, and a liquid crystal 5 projector according to Comparative Example IB were prepared in the same manner as in Example 1, IA, and IB, respectively, provided that 15g of 2-(l-methoxypropyl) acetate (boiling point 145°C) included in the polymerizable composition in Example 1 was changed to 15g of methyl ethyl ketone (boiling point 80 0 C), and were evaluated.
  • the viscosity of the polymerizable composition at a temperature of 2O 0 C is 5cP. o (Comparative Example 2)
  • Table 1 shows that the optically anisotropic layers according to Examples 1 through 21 each exhibit a more favorable result of haze (%) without any occurrences of surface anomaly as compared with the optically anisotropic layers according to Comparative Examples 1 to 4.
  • Table 2 shows that the optically anisotropic layers according to Examples 1 through 21 each exhibit a more favorable result of haze (%) without any occurrences of surface anomaly as compared with the optically anisotropic layers according to Comparative Examples 1 to 4.
  • Table 2 shows that the liquid crystal displays according to Examples IA through 21 A each excel in viewing angle dependency and have a wide viewing angle as compared with the liquid crystal displays according to Comparative Examples IA to 4A, and the liquid crystal projectors according to Examples IB through 21B respectively have a high contrast as compared with the liquid crystal projectors according to Comparative Examples IB to 4B.
  • a polymerizable composition according to the present invention, an optically anisotropic layer comprising the polymerizable composition, an optical compensatory element including the optically anisotropic layer, and a liquid crystal display comprising the optical compensatory element can be suitably used typically in mobile phones, monitors for personal computers, television sets, and liquid crystal projectors.

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Abstract

The object of the invention is to provide a polymerizable composition which can optically compensate a liquid crystal layer under a condition for displaying black more precisely and prevent light leakage at a wide viewing angle and is suitably used for optical compensatory elements; an optically anisotropic layer containing the polymerizable composition; a method for manufacturing the optically anisotropic layer; and a liquid crystal display and a liquid crystal projector both capable of producing a high-quality image at a wide viewing angle, a high contrast, high quality images and being longer-lasting, using an optical compensatory element comprising the optically anisotropic layer. To meet the object, the polymerizable composition comprises a liquid crystal compound and a solvent comprising any one of compounds selected from an alkyl acetyl compound whose boiling point is 100 C or more, a hydroxy carboxylic acid alkyl ester compound, and an alkoxy-substituted alkyl carboxylic acid alkyl ester compound.

Description

POLYMERIZABLE COMPOSITION, OPTICALLY ANISOTROPIC LAYER AND METHOD FOR MANUFACTURING THEREOF, OPTICAL COMPENSATORY ELEMENT, LIQUID CRYSTAL DISPLAY AND LIQUID CRYSTAL PROJECTOR
BACKGROUND OF THE INVENTION Field of the Invention
The present invention relates to a polymerizable composition, an optically anisotropic layer suitably used for optical compensatory elements or the like and a method for manufacturing the polymerizable composition and the optically anisotropic layer. The present invention further relates to an optical compensatory element, a liquid crystal display, and a liquid crystal projector. Description of the Related Art
Liquid crystal displays (LCDs) have been increasingly developed and used typically in mobile phones, monitors for personal computers, television sets and liquid crystal projectors.
Such liquid crystal displays serve to operate a liquid crystal and electrically control light passing through the liquid crystal to show light and dark gradation on a screen to thereby display characters and images. Examples of the mode for operating the liquid crystal are a twisted nematic (TN) mode, a vertical alignment (VA) mode, an in-plane switching (IPS) mode, an optically compensatory bend (OCB) mode, and an electrically controlled birefringence (ECB) mode.
TFT (Thin Film Transistor)-LCDs are often used as the liquid crystal displays and often operated in the TN mode for operating the liquid crystal. Liquid crystal displays for use in a variety of applications require a high contrast, and liquid crystal displays of the VA mode have been increasingly developed.
A liquid crystal display of the TN mode comprises two glass substrates, a nematic liquid crystal twisted by 90 degrees and encapsulated in between the two glass substrates, and a pair of polarizing plates arranged so as to sandwich the two glass substrates in a cross nicol manner. When no voltage is applied, linearly polarized light passes through the polarizing plate near to a polarizer, the plane of polarization of the light is then twisted by 90 degrees in the liquid crystal layer, and the light passes through the polarizing plate near to an analyzer to display white. Upon application of a sufficient voltage, the direction of alignment of the liquid crystal becomes substantially perpendicular to the liquid crystal panel, linearly polarized light passing through the polarizing plate near to the polarizer passes through the liquid crystal layer without changing its optical polarization and reaches the polarizing plate near to the analyzer to thereby display black.
A liquid crystal display of the VA mode comprises two glass substrates, a nematic liquid crystal encapsulated in between the two glass substrates so as to be aligned vertically or aligned vertically and obliquely, and a pair of polarizing plates arranged so as to sandwich the two glass substrates in a cross nicol manner. When no voltage is applied, linearly polarized light passes through the polarizing plate near to a polarizer, passes through the liquid crystal layer without substantially changing its plane of polarization and reaches a polarizing plate near to an analyzer so as to display black. Upon application of a sufficient voltage, the direction of alignment of the liquid crystal changes to being in parallel with the liquid crystal panel and twisted by 90 degrees, linearly polarized light passes through the polarizing plate near to the polarizer, the plane of polarization of the light is twisted by 90 degrees in the liquid crystal layer, and the light passes through the polarizing plane near to the analyzer so as to display white.
Such liquid crystal displays operated according to these display modes show viewing angle dependency, in which display properties are deteriorated when the display is viewed from an oblique direction. For example, the contrast is decreased and/ or tone reversal occurs in which light and dark toner is reversely displayed. In spite of displaying black requested, the viewing angle dependency is caused by light leakage in which the display of the liquid crystal display may not become completely black at some viewing angles.
Accordingly, various optical compensatory films for avoiding the viewing angle dependency have been proposed. According to the technique, the phase difference of light passing through a liquid crystal layer under a condition for displaying black and the phase difference of an optically anisotropic layer are combined so as to optically compensate the liquid crystal layer under a condition for displaying black three-dimensionally to thereby avoid light leakage at every angle. The present applicant, for example, have proposed an optical compensatory film in Patent Literature 1. The optical compensatory film comprises a support, such as a triacetate cellulose (TAC) film, and an optically anisotropic layer arranged on or above the support, in which the optically anisotropic layer comprises a compound containing a discotic structural unit and having an optical anisotropy, the disc surface of the discotic structural unit is oblique to the surface of the support, the optically anisotropic layer is in a hybrid alignment where an angle formed between the disc surface of the discotic structural unit and the surface of the support varies in a thickness direction of the optically anisotropic layer by applying to the surface of the support a coating solution which comprises the compound containing the discotic structural unit to be aligned and fixed in its structure. In the optical compensatory film, the discotic structural unit of the optically anisotropic layer is arrayed so as to form mirror symmetry with the liquid crystal layer under a condition for displaying black. Thus, the liquid crystal layer under a condition for displaying black is optically compensated in optical properties of the entire multilayered structure comprising the support and the discotic structural unit. The light leakage can be prevented at a wide range of viewing angles.
This technique successfully reduces the viewing angle dependency of liquid crystal displays and enlarges the viewing angle by using the optical compensatory film. However, a further wider viewing angle and a higher contrast are required to respond to increasing demands for large-screen liquid crystal monitors and liquid crystal projectors to display in a large screen. Among them, in particular, liquid crystal projectors required a higher contrast, because light entering a liquid crystal cell at various incident angles is integrated by the action of a projection lens and is enlarged and projected onto a screen therein. The optical compensatory film must be further improved when used in these applications.
With the optical compensatory film, it is hard to improve coating property when applying to the support the compound comprising the liquid crystal layer and the optically anisotropic layer having a discotic structural unit, and the optically anisotropic layer is likely to vary in thickness. Thus, unevenness of the thickness of the optically anisotropic layer makes it difficult that the optically anisotropic layer has the desired optical properties with a high degree of precision and makes it impossible to prevent the light leakage at a wide range of viewing angles.
Accordingly, the optical compensatory film is insufficient to optically compensate a liquid crystal layer under a condition for displaying black highly precisely and to prevent light leakage at a wide range of viewing angles so as to meet the demands in recent years for large-screen displaying such as for the liquid crystal projectors.
In addition, since the optically anisotropic layer is produced using methyl ethyl ketone (MEK) which is highly volatile, it causes abnormalities in the surface in a dried condition and requires a large scale recycling system for disposing of volatile organic compounds.
Patent Literature 1 Japanese Patent Application Laid-Open (JP-A) No. 08-50206
SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a polymerizable composition capable of optically compensating a liquid crystal layer under a condition for displaying black further highly precisely and preventing light leakage at a wide range of viewing angles and be suitably used for optical compensatory elements, and to provide an optically anisotropic layer which comprises the polymerizable composition, a method for manufacturing the optically anisotropic layer, an optical compensatory element which comprises the optically anisotropic layer, and a liquid crystal display and a liquid crystal projector, each of which is capable of producing a high-quality image at a wide viewing angle, a high contrast, high quality images and being longer-lasting by using the optical compensatory element.
A polymerizable composition according to the present invention comprises a polymerizable liquid crystal compound and a solvent. The solvent comprises any one of compounds selected from (A) an alkyl acetyl compound having a boiling point of 1000C or more, (B) a hydroxy carboxylic acid alkyl ester compound, and (C) an alkoxy-substituted alkyl carboxylic acid alkyl ester compound. According to the polymerizable composition of the present invention, it allows uniformizing the thickness of an optically anisotropic layer, obtaining the desired optical properties in the optically anisotropic layer with a high degree of precision and preventing light leakage at a wide range of viewing angles. The optically anisotropic layer of the present invention comprises the polymerizable composition according to the present invention, which enables producing an optically anisotropic layer having a uniform thickness, obtaining the desired optical properties in the optically anisotropic layer with high precision, and preventing light leakage at a wide range of viewing angles. A liquid crystal display according to the present invention comprises a liquid crystal device including at least one pair of electrodes and a liquid crystal device having liquid crystal molecules encapsulated in between the at least one pair of electrodes, an optical compensatory element arranged on or above any one of the light incident surface and the light output surface of the liquid crystal device or both of the surfaces, and at least one polarizing element facing the liquid crystal device and the optical compensatory element, in which the optical compensatory element is the optical compensatory element according to the present invention. The liquid crystal display can display a high-contrast and high-quality of image at a wide viewing angle. A liquid crystal projector according to the present invention comprises a liquid crystal display, a light source for irradiating light to the liquid crystal display, and a projection optical system for forming an image on a screen from light optically modulated by the liquid crystal display, in which the optical compensatory element is the optical compensatory element according to the present invention. The liquid crystal projector can project a high-contrast and high-quality of image at a wide viewing angle.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a sectional view showing an example of the optical compensatory element according to a first configuration of the present invention.
FIG. 2 is a sectional view showing an example of the optical compensatory element according to a second configuration of the present invention.
FIG. 3 is a sectional view showing an example of the optical compensatory element according to a third configuration of the present invention. FIG. 4 is a sectional view showing an example of the optical compensatory element according to a fourth configuration of the present invention.
FIG. 5 is a sectional view showing an example of the optical compensatory element according to a fifth configuration of the present invention.
FIG. 6 is a sectional view showing an example of the optical compensatory element according to a sixth configuration of the present invention.
FIG. 7 is a sectional view showing an example of the optical compensatory element according to a seventh configuration of the present invention.
FIG. 8 is a sectional view showing an example of the optical compensatory element according to an eighth configuration of the present invention. FIG. 9 is a schematic view showing an example of the liquid crystal display according to the present invention.
FIG. 10 is a schematic view showing another example of the liquid crystal display according to the present invention.
FIG. 11 is a schematic view showing still another example of the liquid crystal display according to the present invention. FIG. 12 is a schematic view showing a still more example of the liquid crystal display according to the present invention.
FIG. 13 is an outside view showing an example of a rear-projection liquid crystal projector according to the present invention. FIG. 14 is a block diagram showing an example of a projection unit of the liquid crystal projector of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS (Polymerizable composition) The polymerizable composition according to the present invention comprises a polymerizable liquid crystal compound and a solvent whose boiling point is relatively high and further comprises other components suitably selected in accordance with the intended use. - Polymerizable liquid crystal compound - The polymerizable liquid crystal compound is not particularly limited and may be suitably selected in accordance with the intended use, provided that the compound has a functional group capable of being polymerized or cross-linked with a compound which can be formed in a direction of alignment. The polymerizable liquid crystal compound, for example, is preferably a polymerizable liquid crystal compound comprising a liquid crystal compound whose alignment can be fixed, is more preferably a rod-shaped, discotic or banana-shaped liquid crystal compound and is still more preferably a discotic liquid crystal compound. The polymerizable liquid crystal compound may further comprise any other components suitably selected in accordance with the intended use. The polymerizable liquid crystal compound comprising a rod-shaped liquid crystal compound is not particularly limited and may be suitably selected in accordance with the intended use. Examples thereof include a polymerizable liquid crystal composition capable of fixing the alignment of the rod-shaped liquid crystal compound using a polymer binder, and a polymerizable liquid crystal composition having a polymerizable group capable of fixing the alignment of the liquid crystal compound as a result of polymerization. Among them, a polymerizable liquid crystal compound having a polymerizable group is preferred.
The rod-shaped liquid crystal composition (rod-shaped liquid crystal molecule) is not particularly limited and may be suitably selected in accordance with the intended use. Examples of the rod-shaped liquid crystal compound (rod-shaped liquid crystal molecule) include azomethines, azoxies, cyanobiphenyls, cyanophenyl esters, benzoic esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, alkoxy-substituted phenylpyrimidines, phenyldioxanes, tolanes, and alkenylcyclohexylbenzonitriles.
Examples of the polymerizable liquid crystal compound comprising a rod-shaped liquid crystal compound are polymeric liquid crystal compounds formed by polymerization of a rod-shaped liquid crystal compound represented by the following Structural Formula (1) and having low-molecular polymerizable groups.
Q 1 - L 1 -A 1 - L 3 -M- L 4-A 2 - L 2 - Q 2 Structural Formula (1)
In Structural Formula (1), Q1 and Q2 independently represent a polymerizable group; L1, L2, L3 and L4 independently represent a single bond or a divalent linkage group, wherein at least one of L2 and L3 represents -O-CO-O-; A1 and A2 independently represent a spacer group having 2 to 20 carbon atoms; and "M" represents a mesogenic group.
The polymerizable liquid crystal compound comprising a discotic liquid crystal compound is not particularly limited and may be suitably selected in accordance with the intended use. Examples thereof include a polymerizable liquid crystal compound capable of fixing the alignment of the discotic liquid crystal compound through the use of a polymer binder, and a polymerizable liquid crystal compound having a polymerizable group capable of fixing the alignment of the discotic liquid crystal compound as a result of polymerization. Among them, the polymerizable liquid crystal compound having the polymerizable group is preferred.
The structure of the polymerizable liquid crystal compound having the polymerizable group includes, for example, a structure having one or more linkage groups introduced between a discotic core and the polymerizable group. Specific suitable examples of the polymerizable liquid crystal compound are compounds represented by the following Structural Formula (2).
D (— L — P) n Structural Formula (2)
In Structural Formula (2), "D" represents a discotic core; "L" represents a divalent linkage group; "P" represents a polymerizable group; and "n" represents an integer of 4 to 12. Plural divalent linkage groups "L" and plural polymerizable groups "P" may be different from each other in combination, but these groups are preferably identical in their repetition. Two or more discotic cores "D" may be used herein.
Specific examples of the discotic core D in Structural Formula (2) are discotic cores represented by the following Structural Formulas (Dl) to (D15):
(Dl) (D2)
Figure imgf000013_0001
(D3) (D4)
Figure imgf000013_0002
(D5) (D6)
Figure imgf000013_0003
(D9) (DlO)
Figure imgf000014_0001
(DIl)
Figure imgf000014_0002
(D12)
Figure imgf000014_0003
Figure imgf000015_0001
The divalent linkage group "L" in Structural Formula (2) is not particularly limited and may be suitably selected in accordance with the intended use. Preferred examples thereof are an alkylene group, an alkenylene group, arylene group, -CO-, -NH-, -O-, -S-, and a combination of these groups, of which a divalent linkage group comprising two or more divalent groups selected from an alkylene group, an alkenylene group, an arylene group, -CO-, -NH-, -O-, and -S- is more preferred. Among them, a divalent linkage group comprising two or more divalent groups selected from an alkylene group, an alkenylene group, an arylene group, -CO-, and -O- is still more preferred.
The alkylene group preferably has 1 to 12 carbon atoms. The alkenylene group preferably has 2 to 12 carbon atoms. The arylene group preferably has 6 to 10 carbon atoms. Each of the alkylene group, the alkenylene group, and the arylene group may have one or more substituents such as alkyl groups, halogen atoms, cyano groups, alkoxy groups, and acyloxy groups. Specific examples of the divalent linkage group L include -AL-CO-O-AL-, -AL-CO-O-AL-O-, -AL-CO-O-AL-O-AL-, -AL-CO-O-AL-O-CO-, -CO-AR-O-AL-, -CO-AR-O-AL-O-, -CO-AR-O-AL-O-CO-, -CO-NH-AL-, -NH-AL-O-, -NH-AL-O-CO-, -O-AL-, -O-AL-O-, -O-AL-O-CO-, -O-AL-O-CO-NH-AL-, -O- AL-S-AL-, -O-CO-AL-AR-O-AL-O-CO-, -O-CO- AR-O-AL-CO-, -O-CO- AR-O-AL-O-CO-, -O-CO-AR-O- AL-O-AL-O-CO-,
-O-CO- AR-O- AL-O-AL-O-AL-O-CO-, -S-AL-, -S-AL-O, -S-AL-O-CO, -S-AL-S-AL-, and -S-AR-AL-.
In the specific examples of the divalent linkage group "L", the left hand is bound to the discotic core "D", and the right hand is bound to the polymerizable group "P". The symbol AL represents an alkylene group or an alkenylene group; and AR represents an arylene group.
The polymerizable group P in Structural Formula (2) is not particularly limited and may be suitably selected in accordance with the type of the polymerization reaction. Preferred examples thereof include an unsaturated polymerizable group and epoxy group, of which an ethylenically unsa]turated polymerizable group is more preferred. Specific examples of the polymerizable group P are polymerizable groups represented by the following Structural Formulas (Pl) to (P18).
(Pi) (P2) (P3)
-CH=CH2 — C≡CH — CH2-C=CH
(P4) (P5) (P6)
-NH2 -SO3H
~— CHg-CH — CH2
(P7) (P8) (P9)
~~"C=CH2 -CH=CH-CH3 -N=C=S
CH3 (PlO) (PIl) (P12) -SH -CHO —OH
(P13) (P14) (P15) -CO2H -N=C=O -CH=CH-C2H5
(P16) (P17) (P18)
Figure imgf000017_0001
In the polymerizable groups represented by Structural Formulas (Pl) to (P18), V represents an integer of 4 to 12 and is determined according to the type of the discotic core "T)".
The polymerizable liquid crystal compounds thereof can be referenced, for example, in Patent Application Laid-Open 0P-A) Nos. 09-104656, 11-92420, 2000-34251, 2000-44507, 2000-44517, and 2000-86589. - Other components -
The other components which the polymerizable liquid crystal compound may comprise are not particularly limited and may be suitably selected in accordance with the intended use. Examples thereof are a polymerization initiator for initiating the polymerization reaction of the above-noted polymerizable liquid crystal compound.
The polymerization initiator is not particularly limited and may be suitably selected in accordance with the intended use. Examples thereof include a thermal polymerization initiator for initiating a thermal polymerization reaction, and a photopolymerization initiator for initiating a photopolymerization reaction, of which the photopolymerization initiator is more preferred.
Specific examples of the photopolymerization initiator include α-carbonyl compounds (described in US Patent No. 2,367,661 and No. 2,367,670); acyloin ethers (described in US Patent No. 2,448,828); α-hydrocarbon-substituted aromatic acyloin compounds (described in US Patent No. 2,722,512); polynuclear quinine compounds (described in US Patent No. 3,046,127, and No. 2,951,758; combinations of a triarylimidazole dimer and p-aminophenyl ketone (described in US Patent No. 3,549,367); acridine and phenazine compounds (described in JP-A No. 60-105667 and US Patent No. 4,239,850); and oxadiazole compounds (described in US Patent No. 4,212,970).
The content of the photopolymerization initiator in the polymerizable liquid crystal compound is not particularly limited and may be suitably selected in accordance with the intended use. For example, it is preferably 0.01% by mass to 20% by mass of the solid content of the coating solution for the polymerizable liquid crystal compound, and more preferably 0.5% by mass to 5% by mass thereof.
Light irradiating means used in the polymerization reaction is not particularly limited and may be suitably selected in accordance with the intended use. For example, it is preferably ultraviolet rays. The irradiation energy of the light irradiating means is preferably 20J/ cm2 to 5OJ/ cm2 and more preferably lOOmJ/cm2 to 80OmJ/ cm2. The light irradiation may be carried out with heating, for accelerating the photopolymerization reaction. - Solvent - The solvent comprises any one of compounds selected from (A) an alkyl acetyl compound having a boiling point of 100°C or more; (B) a hydroxy carboxylic acid alkyl ester compound; and (C) an alkoxy-substituted alkyl carboxylic acid alkyl ester compound; an alkyl ketone compound and further comprises other components in accordance with the necessity. The viscosity of the polymerizable composition needs to be adjusted to a desired value depending on the solvent in order to apply the above-noted individual components for forming the optically anisotropic layer to one surface of a support to form a uniform (even) layer. It is preferred that the solvent efficiently dissolves the materials of the polymerizable composition and a compound which can be immediately removed upon preparation of the polymerizable composition is used. Further, the solvent preferably has a boiling point of 100°C or more in the present invention.
< (A) Solvent comprising an alkyl acetyl compound having a boiling point of 1000C or more > The solvent comprising an alkyl acetyl compound is preferred to have a boiling point high enough to keep from causing deterioration of other component materials, since the solvent is to be used for obtaining a suitable evaporation rate when coating the solution of the polymerizable composition. Specifically, a boiling point of 100°C or more is particularly preferable. The solvent comprising an alkyl acetyl compound having a boiling point of
1000C or more is not particularly limited and may be suitably selected in accprdance with the intended use. Examples thereof include alkoxy alkyl acetate, hydroxy alkyl acetate, dialkyl acetate, and alkoxy hydroxy alkyl acetate, of which alkoxy alkyl acetate is particularly preferable. The alkoxy alkyl acetate is not particularly limited and may be suitably selected in accordance with the intended use, provided that it can dissolve the polymerizable liquid crystal compound to prepare a coating solution of the polymerizable liquid crystal compound. Examples of the alkoxy alkyl acetate solvent are propylene glycol monoalkyl ether acetate, 1-methoxymethyl acetate, 2-butoxyethyl acetate, 2-propoxyethyl acetate, 2-methoxyethyl acetate, 2-ethoxyethyl acetate, 3-methoxypropyl acetate, 3-ethoxypropyl acetate, 2-methoxypropyl acetate, 2-ethoxypropyl acetate, 2-methoxybutyl acetate, 2-ethoxybutyl acetate, 3-methoxybutyl acetate, 3-ethoxybutyl acetate, 4-methoxybutyl acetate, 4-ethoxybutyl acetate, 2-methoxypentyl acetate, 2-ethoxypentyl acetate, 3-methoxypentyl acetate, 3-ethoxypentyl acetate, 4-methoxypentyl acetate, 4-ethoxypentyl acetate, 5-methoxypentyl acetate, and 5-ethoxypentyl acetate.
Each of the alkoxy alkyl acetates above may have one or more substituents such as alkyl groups, and alkoxy groups. Specific examples of the alkoxy alkyl acetate having one or more substituents from alkyl groups and alkoxy groups are 2-(l-methoxypropyl) acetate, 2-(l-methoxybutyl) acetate, 3-methoxy-3-methylbutyl acetate, 3-ethoxy-3-methylbutyl acetate, 4-methoxy-4-methylpentyl acetate, and 4-ethoxy-4-methylpentyl acetate.
Among them, from the perspective of coating property, evaporation rate of the solvent, and latent heat viscosity of evaporation, 3-methoxybutyl acetate, 3-ethoxybutyl acetate, 3-methoxy-3-methylbutyl acetate, 2-(l-methoxypropyl) acetate, 2-(l-methoxybutyl) acetate are preferred. 2-(l~methoxypropyl) .acetate, 2-(l-methoxybutyl) acetate, 3-methoxy-3-methylbutyl acetate, and propylene glycol monoalkyl ether acetate are particularly preferred. In Examples of the present invention, 2-(l-methoxypropyl) acetate having a boiling point of 145°C was used as the solvent comprising an alkyl acetyl compound having a boiling point of 100°C or more.
Each of these alkoxy alkyl acetates may be used alone or in combination of two or more.
The content of the alkoxy alkyl acetate in the polymerizable liquid crystal compound is, as long as the polymerizable liquid crystal compound can be coated, not particularly limited and may be suitably selected in accordance with the intended use, but the alkoxy alkyl acetate preferably has a content of 200 parts by mass to 1,000 parts by mass relative to 100 parts by mass of the polymerizable liquid crystal compound. More preferably, the alkoxy alkyl acetate has a content of 200 parts by mass to 500 parts by mass relative to 100 parts by mass of the polymerizable liquid crystal compound.
When the content of the alkoxy alkyl acetate is less than 200 parts by mass relative to 100 parts by mass of the polymerizable liquid crystal compound, it may degrade coating property and may cause unevenness in film thickness, while the content of the alkoxy alkyl acetate is more than 1,000 parts by mass relative to 100 parts by mass of the polymerizable liquid crystal compound, the evaporation rate of the alkoxy alkyl acetate becomes delayed and it may also result in unevenness in film thickness. < (B) Hydroxy carboxylic acid alkyl ester compound > The hydroxy carboxylic acid alkyl ester compound (B) is, as long as it can dissolve the polymerizable liquid crystal compound to prepare a coating splution for the polymerizable liquid crystal compound, not particularly limited and may be suitably selected in accordance with the intended use. Examples of the hydroxy carboxylic acid alkyl ester compound include methyl lactate, ethyl lactate, butyl lactate, hexyl lactate, octyl lactate, 3-hydroxy methyl butanoic acid, 3-hydroxy ethyl butanoic acid, 4-hydroxy methyl butanoic acid, 4-hydroxy ethyl butanoic acid, 2-hydroxy methyl hexanoic acid, 2-hydroxy ethyl hexanoic acid, 6-hydroxymethyl hexanoic acid, and 6-hydroxyethyl hexanoic acid.
Each of the hydroxy carboxylic acid alkyl ester compounds may have one or more substituents such as alkyl groups and alkoxy groups. Preferred examples of the hydroxy carboxylic acid alkyl ester compound having the substituents are methyl tartrate, diethyl tartrate, hydroxy dimethyl malonate, hydroxy diethyl malonate, hydroxy dibutyl malonate, 2-hydroxy-4-methyl pentanoic acid ethyl, 2-hydroxy-2-methylmethyl propionate, and 2-hydroxy-2-ethylmethyl propionate. Among them, from the perspective of coating property, evaporation rate and latent heat viscosity of evaporation, it is preferably methyl lactate, ethyl lactate, butyl lactate, methyl 3-hyroxy butanoic acid, ethyl 3-hydroxy butanoic acid, methyl 4-hydroxy butanoic acid, ethyl 4-hydroxy butanoic acid, methyl 2-hydroxy-2-methyl propionate, and ethyl 2-hydroxy-2-methyl propionate, of which ethyl 3-hydroxy butanoic acid, methyl 3-hydroxy butanoic acid, ethyl lactate, and butyl lactate are more preferred.
The solvent to be used in coating the polymerizable composition is preferred to have a boiling point high enough to keeping from causing deterioration of other component materials and to have a boiling point of 100°C or more from the perspective of evaporation rate of the solvent. In Examples of the present invention, ethyl lactate having a boiling point of 154°C, butyl lactate having a boiling point of 185°C to 187°C, 3-hydroxyethyl butanoic acid having a boiling point of 170°C and the like are respectively used.
As the hydroxy carbonic acid alkyl ester compound (B), Each of these solvents may be used alone or in combination of two or more.
The content of the hydroxy carboxylic acid alkyl ester compound (B) is not particularly limited and may be suitably selected in accordance with the intended use, provided that the polymerizable liquid crystal compound can be coated. The content of hydroxy carboxylic acid alkyl ester compound is preferably 250 parts by mass to 2,000 parts by mass relative to 100 parts by mass of the polymerizable liquid crystal compound, and more preferably 300 parts by mass to 1,000 parts by mass.
When the content of the hydroxy carboxylic acid is less than 250 parts by mass relative to 100 parts by mass of the polymerizable liquid crystal compound, coating property may be degraded and may cause unevenness in film thickness, while the content of the hydroxy carboxylic acid is more than 2,000 parts by mass relative to 100 parts by mass of the polymerizable liquid crystal compound, the evaporation rate of the hydroxy carboxylic acid alkyl ester compound (B) becomes delayed and may also result in unevenness in film thickness. < (C) Alkoxy-substituted alkyl carboxylic acid alkyl ester compound > The alkoxy-substituted alkyl carboxylic acid alkyl ester compound is, as long as it can dissolve the polymerizable liquid crystal compound to prepare a coating solution for the polymerizable liquid crystal compound, not particularly limited and may be suitably selected in accordance with the intended use. Examples of the alkoxy-substituted alkyl carboxylic acid alkyl ester compound are 0-methyl lactate methyl, 0-ethyl lactate ethyl, 0-methyl lactate butyl, methyl 2-ethoxy propionate, ethyl 2-ethoxy propionate, ethyl 3-ethoxyl propionate, ethyl 3-methoxy butanoic acid, ethyl 3-ethoxy butanoic acid, ethyl 4-methoxy butanoic acid, methyl 2-methoxy pentanoic acid, methyl 2-ethoxy pentanoic acid, methyl 2-methoxy propionate, and methyl 3-methoxy propionate. Each of these alkoxy-substituted carboxylic alkyl esters may have one or more substituents such as alkyl groups, and alkoxy groups. Specific examples of the alkoxy-substituted carboxylic alkyl ester having one or more substituents from alkyl groups and alkoxy groups are methoxy malonic acid dimethyl ester, ethoxy malonic acid dimethyl ester, and methoxy malonic acid diethyl ester. Among them, from the perspective of coating property, evaporation rate and latent heat viscosity of evaporation, ethyl 2-ethoxy propionate, methyl 2-methoxy propionate, ethyl 3-ethoxy propionate or methyl 3-metoxy propionate are preferable.
The solvent to be used in coating the polymerizable composition is preferred to have a boiling point high enough to keep from causing deterioration of other component materials and to have a boiling point of 100°C or more from the perspective of evaporation rate. In Examples of the present invention, ethyl 3-ethoxy propionate having a boiling point of 166°C and methyl 3-methoxy propionate having a boiling point of 142°C to 143°C are respectively used. Each of these alkoxy-substituted alkyl carboxylic acid alkyl ester compounds may be used alone or in combination of two or more.
The content of the alkoxy-substituted alkyl carboxylic acid alkyl ester compound (C) is not particularly limited and may be suitably used in accordance with the intended use, provided that the polymerizable liquid crystal compound can be coated. The content of the alkoxy-substituted alkyl carboxylic acid alkyl ester compound (C) is preferably 250 parts by mass to 2,000 parts by mass relative to 100 parts by mass of the polymerizable liquid crystal compound, and more preferably 300 parts by mass to 1,000 parts by mass.
When the content of the alkoxy-substituted alkyl carboxylic acid alkyl ester compound (C) is less than 250 parts by mass, coating property degrades, and this may result in unevenness in film thickness. While the content of the alkoxy-substituted alkyl carboxylic acid alkyl ester compound (C) is more than 2,000 parts by mass, the evaporation rate of the alkoxy-substituted alkyl carboxylic acid alkyl ester compound (C) becomes delayed and may also result in unevenness in film thickness. The respective contents of the alkoxy-substituted alkyl carboxylic acid alkyl ester compound (C) and the hydroxy carboxylic acid alkyl ester compound (B) are not particularly limited and may be suitably selected in accordance with the intended use, provided that the polymerizable liquid crystal compound can be coated. The content of the alkoxy-substituted alkyl carboxylic acid alkyl ester compound (C) relative to 100 parts by mass of the polymerizable liquid crystal compound is preferably 200 parts by mass to 1,000 parts by mass, and more preferably 300 parts by mass to 800 parts by mass. On the other hand, the content of the hydroxy carboxylic acid alkyl ester compound (B) relative to 100 parts by mass of the polymerizable liquid crystal compound is preferably 20 parts by mass to 1,000 parts by mass, and more preferably 50 parts by mass to 500 parts by mass. The content of the alkoxy alkyl acetate compound relative to 100 parts by mass of the polymerizable liquid crystal compound is preferably 20 parts by mass to 1,000 parts by mass, and more preferably 50 parts by mass to 500 parts by mass. When the respective contents of the alkoxy-substituted alkyl carboxylic acid alkyl ester compound (C), the hydroxy carboxylic acid alkyl ester compound (B) and the alkoxy alkyl acetate compound are individually less than 200 parts by mass relative to 100 parts by mass of the polymerizable liquid crystal compound, coating property becomes degraded and may result in unevenness in film thickness. When the respective contents thereof are individually more than 1,000 parts by mass, the individual evaporation rates of the alkoxy-substituted alkyl carboxylic acid alkyl ester compound (C), the hydroxy carboxylic alkyl ester compound (B), and the alkoxy alkyl acetate compound are delayed and may result in unevenness in film thickness. < Alkyl ketone compound > The alkyl ketone compound is not particularly limited and may be suitably selected in accordance with the intended use, provided that it can dissolve the polymerizable liquid crystal compound to prepare a coating solution for the polymerizable liquid crystal compound. Examples of the alkyl ketone compound are acetone, methyl ethyl ketone, diethyl ketone, methyl butyl ketone, methyl pentyl ketone, ethyl butyl ketone, dipropyl ketone, dibutyl ketone, dipentyl ketone, methyl octyl ketone, ethyl pentyl ketone, cyclopentanon, and cyclohexane.
Each of these alkyl ketone compounds may have one or more substituents such as alkyl groups, alkoxy groups, and hydrogen groups. Specific examples of the alkyl ketone compounds having one or more substituents from alkyl groups, alkoxy groups, and hydrogen groups include methoxyacetone, ethoxyacetone, 5-chloropentan-2-one, 2-methyl cyclopentan, 2-methyl cyclohexanon, 3-methyl cyclohexanon, 2, 6-dimethyl cyclohexanon, and 4-methoxy cyclohexanon.
Among them, from the perspective of coating property, evaporation rate, latent heat viscosity of evaporation, acetone, methyl ethyl ketone, methyl butyl ketone, cyclohexanon, and 2-methyl cyclohexanon are preferable. Each qf these alkyl ketone compounds may be used alone in combination of tow or more.
The respective contents of the alkoxy-substituted alkyl carboxylic acid alkyl ester compound (C) and the hydroxy carboxylic acid alkyl ester compound (B) are not particularly limited and may be suitably used in accordance with the intended use, provided that the polymerizable liquid crystal compound can be coated. The content of the alkoxy-substituted alkyl carboxylic acid alkyl ester compound (C) relative to 100 parts by mass of the polymerizable liquid crystal compound is preferably 250 parts by mass to 2,000 parts by mass, and more preferably 300 parts by mass to 1,000 parts by mass. The content of the hydroxy carboxylic acid alkyl ester compound (B) relative to 100 parts by mass of the polymerizable liquid crystal compound is preferably 250 parts by mass to 2,000 parts by mass, and more preferably 300 parts by mass to 1,000 parts by mass. When the respective contents of the alkoxy-substituted alkyl carboxylic acid alkyl ester compound (C) and the hydroxy carboxylic acid alkyl ester compound (B) are individually less than 250 parts by mass relative to 100 parts by mass of the polymerizable liquid crystal compound, coating property becomes degraded and may result in unevenness in film thickness and when more than 2,000 parts by mass, evaporation rate of the alkoxy-substituted alkyl carboxylic acid alkyl ester compound (C) and the hydroxy carboxylic acid alkyl ester compound (B) respectively become delayed and may result in unevenness in film thickness.
The content of the alkyl ketone compound is not particularly limited and may be suitably used in accordance with the intended use, provided that the polymerizable liquid crystal compound can be coated. The content of the alkyl ketone compound relative to 100 parts by mass of the polymerizable liquid crystal compound is preferably 5 parts by mass to 200 parts by mass, and more preferably 10 parts by mass to 100 parts by mass.
When the content of the alkyl ketone compound relative to 100 parts by mass of the polymerizable liquid crystal compound is less than 5 parts by mass, coating property becomes degraded and may result in unevenness in film thickness, and when more than 200 parts by mass, the evaporation rate of the alkyl ketone compound becomes delayed and may also result in unevenness in film thickness.
According to the polymerizable composition of the present invention having the above composition, it is possible to obtain an optically anisotropic layer having an uniform (even) thickness and to have the desired optical properties in the optically anisotropic layer with a high degree of precision and to prevent light leakage at a wide range of viewing angles.
The polymerizable composition makes it possible to obtain an optically anisotropic layer with a predetermined shape (configuration) and a high degree of precision in optical properties and to prevent light leakage at a wide range of angle, when prepared, for example, by a inkjet technique, because the polymerizable composition has excellent patterning properties.
Accordingly, it is possible, for example, to obtain an optical compensatory film having a microscopic optically anisotropic layer pattern which responds to each of pixels of RGB (red-green-blue) to have the desired optical properties in a full-color liquid crystal display. The optical compensatory film makes it possible to arbitrarily combine the phase difference of light passing through a liquid crystal layer with respect to each colors of red color, green color, and blue color in a liquid crystal display and the phase difference of the optical compensatory film to optically compensate the liquid crystal layer under a condition for displaying black three-dimensionally, with respect to each colors of red, green and blue and .prevent light leakage when viewed from any direction to eliminate issues of viewing angle dependency.
(Optically Anisotropic Layer) An optically anisotropic layer according to the present invention comprises the polymerizable composition according to the present invention and further comprises any other configurations when necessary.
The polymerizable liquid crystal compound in the polymerizable composition is preferably aligned (in alignment) immediately before a polymerization reaction in forming the optically anisotropic layer, and the alignment (the state of alignment) is not particularly limited and may be suitably selected in accordance with the intended use. For example, the polymerizable liquid crystal compound may be fixed in its structure by a polymerization or a cross-linking to thereby show no liquid crystal appearance in the optically anisotropic layer.
The term "polymerizable liquid crystal compound is aligned (or in alignment)" used herein means that average directions of specific axes of molecules constituting a state of liquid crystal contained in a microdomain in question substantially agree with each other, when a specific axis of molecules constituting the state of liquid crystal derived from the molecular shape is set in a major axis direction in a rod-shaped molecule, and is set in the direction of the normal to a plane in a plane molecule. In other words, it means an alignment of molecules constituting a state of liquid crystal.
In the present invention, when the liquid crystal compound is aligned, the angle formed between the average direction of the liquid crystal compound in the microdomain in question and the lamination direction of the optical compensatory element (the normal direction at the interface between the optically anisotropic layer and the support) is referred to as "angle of alignment", and the projected components of the average direction of the specific axes projected onto the interface is referred to as "direction of alignment".
As the alignment, the liquid crystal compound preferably has an oblique angle of alignment, namely, the angle of alignment is preferably not in uniformly parallel or uniformly perpendicular to a thickness direction of the optically anisotropic layer. The liquid crystal compound is more preferably in a hybrid alignment in which the angle of alignment successively varies in the thickness direction between the upper surface and the lower surface of the optically anisotropic layer.
The angle of alignment in the hybrid alignment is preferably set so as to successively vary from 20°+20° to 65°±25° from the alignment layer toward the air interface.
The angle of alignment and direction of alignment of the polymerizable liquid crystal compound including the above-noted state of liquid crystal, which determine the alignment thereof, are preferably set so as to form mirror symmetry with the liquid crystal layer under a condition for displaying black. The angles of alignment of the liquid crystal compound in the vicinity of the alignment layer, in the vicinity of the air interface, and the average angle of alignment in the optically anisotropic layer are estimates determined by measuring retardations from multiple directions using an ellipsometer (M-150, manufactured by JASCO Corporation), assuming a refractive index ellipsoid model from the measured retardations, and estimating the angles of alignment based on the refractive index ellipsoid model.
The angles of alignment can be determined from the retardations, for example, according to a procedure described in Design Concepts of Discotic Negative Birefringence Compensation Films SID98 DIGEST. The measurement directions of the retardation in determination of the angle of alignment are not particularly limited and may be suitably set in accordance with the intended use, include, for example, a retardation in the direction of the normal to the optically anisotropic layer (ReO), a retardation in a direction at -40° to the normal direction (Re-40) and a retardation in a direction at +40° to the normal direction (Re440). The ReO, Re-40, and Re+40 are determined by changing the observation angle to the respective measurement directions, using the elipsometer.
The other components or configurations which the optically anisotropic layer may comprise are not particularly limited and may be suitably selected in accordance with the intended use and include, for example, an alignment layer for aligning the polymerizable liquid crystal compound in the polymerizable liquid crystal compound. The polymerizable liquid crystal compound is preferably formed on or over an alignment layer typically by coating.
The alignment layer is not particularly limited and may be suitably selected in accordance with the intended use and includes, for example, a rubbed alignment layer comprising an organic compound (preferably a polymer); an alignment layer having a micro groove; an alignment layer comprising an organic compound, such as tricosanoic acid, dioctadecyldimethylammonium chloride or methyl stearate, deposited according a Langmuir-Blodgett method (LB film); an alignment layer comprising an inorganic compound deposited by oblique vapor deposition; and an alignment layer having an aligning function as a result of the application of an electric or magnetic field, or light. Among them, the rubbed alignment layer comprising an organic compound is preferred.
The rubbing can be carried out by any procedure selected in accordance with the intended use. For example, the surface of the film comprising an organic compound is rubbed with paper or cloth several times in a certain direction.
The organic compound is not particularly limited and may be suitably selected in accordance with the alignment condition of the liquid crystal compound (particularly the angle of alignment) and includes, for example, a polymer for an alignment layer which does not reduce the surface energy of the resulting alignment layer, for horizontal alignment of the liquid crystal compound. Preferred examples of the polymer for an alignment layer for aligning the liquid crystal compound in a direction perpendicular to the direction of rubbing are modified polyvinyl alcohol)s (JP-A No. 2002-62427), acrylic copolymers 0P-A No. 2002-98836) and polyimides and polyamic acid (JP-A No. 2002-268068). The alignment layer preferably has a reactive group for improving adhesion with the polymerizable liquid crystal compound and the support. The reactive group is not particularly limited and may be suitably selected in accordance with the intended use. For example, a reactive group may be selected in accordance with the intended use. For example, a reactive group may be introduced into a side chain of a repeating unit of the polymer for an alignment layer, or a cyclic group as a substituent may be introduced into the polymer for an alignment layer.
The alignment layer capable of forming a chemical bond with the polymerizable liquid crystal compound and the support by the action of a reactive group is not particularly limited and may be suitably selected in accordance with the intended use. For example, the alignment layer disclosed in JP-A No. 09-152509 can be used. The thickness of the alignment layer is not particularly limited, may be suitably selected in accordance with the intended use and is preferably O.Olμm to 5μm and more preferably 0.05μm to 2μm. (Method for manufacturing an optical compensatory element) The method for manufacturing an optical compensatory element according to the present invention comprises the processes of applying to at least one surface of the support the polymerizable composition according to the present invention and heating the polymerizable composition up to 130°C or more and may further comprise other processes in accordance with the intended use. As for the support, those similar to an optical compensatory element (which will be described hereinafter) can be used.
The coating solution can be applied to the support (or the alignment layer) according to any suitable procedure known in the art, in accordance with the intended use, such as extrusion coating, direct gravure coating, reverse gravure coating, die coating or spin coating.
The optically anisotropic layer may be prepared by a method in which the polymerizable liquid crystal compound is aligned by using the alignment layer, liquid crystal molecules are fixed while maintaining them being aligned to form an optically anisotropic layer, and the optically anisotropic layer alone is transferred to a support such as a polymer film. The resulting optically anisotropic layer prepared by this method can serve to optically compensate the liquid crystal layer under a condition for displaying black further precisely without considering the effect of birefringence caused by the alignment layer. (Optical compensatory element) An optical compensatory element according to the present invention comprises an optically anisotropic layer on at least one surface of the support, the optically anisotropic layer comprises an optically anisotropic layer according to the present invention and may further comprise other layers when necessary. - Support - The support is not particularly limited and may be suitably selected in accordance with the intended use, provided that the support is transparent enough to allow light to pass through 50% or more of the wavelength of light. Examples of the support include white sheet glass, blue sheet glass, quartz glass, sapphire glass, and an organic polymer film. The material for the organic polymer film is not particularly limited, may be suitably selected in accordance with the intended use and can be in combination of one or more of polymers selected from the polymer groups consisting of, for example, polyarylate polymers, polyester polymers, polycarbonate polymers, norbornene polymers, polyolefin polymers, polyether polymers, polysulfine polymers, polysulfone polymers, polyether-sulfone polymers, cellulose ester polymers such as cellulose acetates, and cellulose diacetate; and poly(meth)acrylic acid ester such as polymethyl methacrylate.
Suitable specific examples of the organic polymer film are polycarbonate copolymers, polyester copolymers, polyester-carbonate copolymers, polyarylate copolymers, of which polycarbonate copolymers are more preferred.
Preferred examples of the polycarbonate copolymers polycarbonate copolymers having a fluorine skeleton, of which polycarbonate copolymers prepared by reacting a bisphenol with phosgene or a compound capable of forming a carbonic ester, such as diphenyl carbonate, are particularly preferred for their excellent optical transparency, thermostability and productivity.
The content of the fluorine skeleton in the polycarbonate copolymer is preferably 1 %by mole to 99% by mole. A repeating unit disclosed in International Publication No. WOOO/ 26705 can be used as the polycarbonate copolymer.
The material for the support is preferably glass derived from the above-noted inorganic materials, in terms of smoothness of the surface of the support.
The thickness of the support is not particularly limited, may be suitably selected in accordance with the intended use and is preferably O.lμm or more. The upper limit of the thickness is preferably 0.5mm to 1.5mm. - Other layers - The other layers for the optical compensatory element is not particularly limited, may be suitably selected in accordance with the intended use and can include, for example, an additional optical anisotropic layer which has optical properties of an ellipsoid having an optically uniaxial negative reflective index, a structurally birefringent layer , a protective layer, and antireflective layer.
The additional functions for the optical anisotropic layer can be added for its function capable of removing effects caused, for example, by an angle of light incidence and liquid crystal in the center portion of a TN mode liquid crystal cell.
The materials of the structurally birefringent layer are not particularly limited, may be suitably selected in accordance with the intended use and include, for example, various organic materials and inorganic materials.
As the organic materials for the structurally birefringent layer , for example, a structurally birefringent layer which is prepared by elongating a plastic film and aligning molecules thereof for inducing birefringence are known in the art. In this case, such a material used as the support may serve as birefringence. For example, a structurally birefringent layer which is prepared by elongating a cellulose triacetate which is used as an optical compensatory film is well known.
As inorganic materials for the structurally birefringent layer , for example, it is preferred to have a multilayered structure where plural inorganic materials each having different refractive indices laminated repeatedly in a regular order in a direction normal to the support, in which the thickness of a repeating unit in changes in refractive indices is shorter than the wavelengths of light in the visible region. Among them, the multilayered film constituting one repeating unit comprising two layers made from two types of inorganic materials is particularly preferred. The respective repeating units of the structurally birefringent layer constituting one repeating unit is not particularly limited and may be suitably selected in accordance with the intended use, provided that the layer is formed with inorganic materials and has properties of an ellipsoid having an optically uniaxial negative refractive index. Preferred examples of the structure are a structure in which plural inorganic materials having different refractive indices are laminated in a regular order in a direction normal to the support, comprises a multilayered film constituting one repeating unit having plural layers in which refraction indices in the laminating direction vary in a regular order, and the thickness of a repeating unit in changes in refractive indices is shorter than the wavelengths of light in the visible region. In particular, a multilayered film constituting one repeating unit comprising two layers made from two types of inorganic materials is preferred.
A birefringent layer constituting respective repeating units, as mentioned above, has a medium equivalent to a medium having a uniform refractive index in a direction the multilayered film is laminated, i.e. in a direction normal to the support, and the structurally birefringent layer has optical properties of an ellipsoicj having a non-oblique and uniaxial negative refractive index as a whole by inducing anisotropy called structural birefringence.
The thickness of a repeating unit in a laminating direction of the multilayered structure is not particularly limited, provided that it is shorter than the wavelengths of light in the visible region, and may be suitably selected from light in the visible region in accordance with the intended use. The "visible region" means a region of wavelengths of 400nm to 700nm, unless otherwise specified. Accordingly, it is preferred that the thickness of a repeating unit in the structure is suitably selected from 400nm to 700nm. With respect to the refractive index of the multilayered film each of the layers having one repeating unit in the region of visible light, when the multilayered film, comprises a plurality of layers (made from three or more different materials), the difference between the maximum refractive index and the minimum refractive index is preferably 0.5 or more. When the multilayered film comprises two different types of materials, the difference in refractive indices of each layer is preferably 0.5 or more.
The refractive index is a value measured at a wavelength of 550nm, unless otherwise specified. The number of layers constituting one repeating unit of the structurally birefringent layer is not particularly limited and may be suitably selected in accordance with the intended use.
The material for the multilayered film constituting one repeating unit which constitutes the structurally birefringent layer is not particularly limited, may be suitably selected in accordance with the intended use, preferably has a combination of plural materials suitably selected from oxide layers, and more preferably has a combination of a SiCh layer and a ΗO2 layer.
Summarizing the above, the retardation of the structurally birefringent layer can be highly precisely prepared with ease by suitably selecting materials of the multilayered film constituting one repeating unit, thicknesses thereof, the number of layers, the repeating lamination length of changes in refractive indices, and the like.
Each of these additional optical anisotropic layer preferably has a retardation (Rth) of 40nm to 200nm when represented by the following equation, and more preferably has a retardation (Rth) of 50nm to 150nm. Rth = {(nx + ny)/2-nz} x d Equation 1 In Equation 1, nX/ ny, and nz respectively represent the refractive indices in axial directions of X, Y, and Z which are respectively perpendicular each other in a structurally birefringent layer when the normal direction to the support is regarded as the Z-axis, and "d" represents a thickness of the optical anisotropic layer.
The number of layers of the multilayered film of the structurally birefringent layer is not particularly limited and may be suitably selected in accordance with the intended use.
The structurally birefringent layer preferably has a thickness such that the above-noted retardation is satisfied. Specifically, the thickness is preferably 20μm to 300μm, more preferably 40μm to 200Pm, still more preferably 50μm to 150μm.
With respect to the functions of the additional optical anisotropic layer, the support itself may have them. When a material, like an elongated cellulose triacetate, is used as the support and only retardation fulfills the functions, the structurally birefringent layer may not be formed. When an optically isotropic material, like glass, is used for the support, it is possible to use the structurally birefringent layer suitably. In this case, the thickness of an optical anisotropic layer made from a material other than the material having birefringence in structure may be suitably determined in the light of functions as a protective film and a support, when the layer comprises the protective film layer and the support.
To a layer on which plural layers each having different refractive indices are alternatively laminated, as mentioned above, functions as an antireflective layer can be given by suitably selecting configurations of each layer from the viewpoint of an optical thickness of layers. When the antireflective layer is used, as the material constituting a layer having different refractive indices, not only inorganic materials but also organic materials and a material with organic materials to which inorganic materials are added can be used, as long as the conditions of configurations for the optical thickness of layer are satisfied.
The protective layer is not particularly limited, may be selected in accordance with the intended use, and includes cellulose esters such as cellulose acetate, cellulose acetate butylate, and cellulose propionate; polycarbonate, polyolefin, polystyrene, and polyester.
Specific preferred examples of the protective layer include polyolefins such as cellulose triacetate, ZEONEX, and ZEONOR (respectively manufactured by ZEON CORPORATION), and ARTON (manufactured by JSR Corporation).
It is also possible to use non-birefringent optical resin materials described in Japanese Patent Application Laid-Open 0P-A) Nos. 08-110402 and 11-293116 can be used for the protective layer.
The alignment axis (slow axis) of the protective layer is arranged in any directions but is preferably in parallel with the longitudinal direction for easy and convenient operation.
The angle formed between the slow axis (alignment axis) of the protective layer and the adsorption axis (stretching axis) of the polarizing film is not particularly limited and may be suitably set in accordance with the intended use of the polarizing plate. When the polarizing film is prepared by using a lateral uniaxial tenter stretching machine, the slow axis (alignment axis) of the protective layer is in a direction substantially perpendicular to the adsorption axis (stretching axis) of the polarizing film.
The retardation of the protective layer is not particularly limited, maybe suitably selected in accordance with the intended use and is preferably, for example, lOnm or less and more preferably 5nm or less when measured by light having wavelength of 632.8nm.
The retardation of the cellulose acetate, if used, is preferably less than 3nm and more preferably 2nm or less for minimizing a variation of the retardation depending on temperature and humidity.
A layer serving to both the additional optical anisotropic layer and a protective layer can be formed by using a film controlled to a desired retardation value.
The material for the antireflective layer is not particularly limited, provided that the material has a structure in which refractive index can be reduced but light transmittance can be increased, may be suitably selected in accordance with the intended use and includes an AR film (Anti Reflection Coat Film), which is known in the art.
< Configuration of Optical Compensatory Element > The optical compensatory element can have any configuration suitably selected in accordance with the intended use. Preferred examples , of the configuration are the following first, second, third, fourth, fifth, sixth, seventh and eighth configurations.
In the following examples of configurations, an optical anisotropic layer according to the first configuration may not necessarily included, because there may be cases where a support has functions of the first optical anisotropic layer or the first optical anisotropic layer is unnecessary from the perspective of functional designing.
(Optical Compensatory Element according to First Configuration) FIG. 1 is a sectional view schematically showing an optical compensatory element according to the first configuration of the present invention.
The optical compensatory element according to the first configuration comprises the support, the first optically anisotropic layer which comprises the structurally birefringent layer arranged on one surface of the support, and two layers of the second optically anisotropic layer, which comprises an optical anisotropic layer and has different direction of alignments, arranged on one surface of the support. Specifically, with reference to FIG. 1, optical compensatory element 10 according to the first configuration comprises alignment layer 4A, second optically anisotropic layer 3A, alignment layer 4B, second optically anisotropic layer 3B and antireflective layer 5B arranged in this order on one surface of support 1, so that the antireflective layer 5B constitutes an outermost surface. The optical compensatory element 10 further comprises first optically anisotropic layer 2 and antireflective layer 5 A arranged in this order on the opposite surface of the support 1 so that the antireflective layer 5A constitutes another outermost surface. The first optically anisotropic layer 2 has an alternatively multilayered structure comprising a TiO2 layer 2 A and a SiO2 layer 2B. The thickness of the respective layers is about 15nm. The first optically anisotropic layer 2 can also serve as an antireflective layer by having such an alternatively multilayered structure. The rubbing directions of the alignment layer 4 A and the alignment layer 4B preferably differ from each other by 90 degrees. By arranging these alignment layers 4A and 4B, the direction of alignments of the liquid crystal compounds in the polymerizable liquid crystal compounds of the second anisotropic layers 3A and 3B can differ from each other by 90 degrees. (Optical Compensatory Element according to Second Configuration) FIG. 2 is a sectional view schematically showing an optical compensatory element according to the second configuration of the present invention.
The optical compensatory element according to the second anisotropic layer arranged on at least one surface of the support. With reference to FIG. 2, optical compensatory element 20 according to the second configuration comprises first optically anisotropic layer 22, alignment layer 24, second optically anisotropic layer 23 and antireflective layer 25B arranged in this order on one surface of support 21, so that the antireflective layer 25B constitutes an outermost surface, and comprises an antireflective layer 25A on the opposite surface of the support 21.
The first optically anisotropic layer 22 can have a similar structure to that of the first optically anisotropic layer 2 in the optical compensatory element 10 according to the first configuration.
Two plies of the optical compensatory element 20 according to the second configuration can be used as a laminate. In this case, rubbing directions of the alignment layers in the respective optical compensatory elements preferably differ from each other by 90 degrees.
Such an optical compensatory element having the respective layers arranged on one surface of the support, as in the optical compensatory element 20 according to the second configuration, can be generally satisfactorily handled and easily prepared, while these properties depend on the materials of the respective layers and combinations thereof. (Optical Compensatory Element according to Third Configuration)
FIG. 3 is a sectional view schematically showing an optical compensatory element according to the third configuration of the present invention. The optical compensatory element according to the third configuration comprises two second anisotropic layers having different direction of alignments arranged on one surface of the support.
With reference to FIG. 3, optical compensatory element 30 according to the third configuration comprises first optically anisotropic layer 32, alignment layer
34A, second optically anisotropic layer 33A, alignment layer 34B, second optically anisotropic layer 33B and antireflective layer 35B arranged in this order on one surface of support 31, so that the antireflective layer 35B constitutes an outermost surface, and comprises antireflective layer 35A on the opposite surface of the support 31.
The first optically anisotropic layer 32 can have a similar structure to that of the first optically anisotropic layer 2 in the optical compensatory element 10 according to the first configuration.
The rubbing directions of the alignment layer 34A and the alignment layer 34B preferably differ from each other by 90 degrees. By arranging these alignment layers 34A and 34B, the direction of alignments of the liquid crystal compounds in the polymerizable liquid crystal compounds of the second anisotropic layers 33A and 33B can differ from each other by 90 degrees. (Optical Compensatory Element according to Fourth Configuration) FIG. 4 is a sectional view schematically showing an optical compensatory element according to the fourth configuration of the present invention.
The optical compensatory element according to the fourth configuration comprises two second anisotropic layers having different direction of alignments arranged with the interposition of the support. With reference to FIG. 4, optical compensatory element 40 according to the fourth configuration comprises first optically anisotropic layer 42, alignment layer 44A, second optically anisotropic layer 43A and antireflective layer 45B arranged in this order on one surface of support 41, so that the antireflective layer 45B constitutes an outermost surface, and comprises alignment layer 44B, second optically anisotropic layer 43B, and antireflective layer 45A in this order on the opposite surface of the support 41.
The first optically anisotropic layer 42 can have a similar structure to that of the first optically anisotropic layer 2 in the optical compensatory element 10 according to the first configuration. The rubbing directions of the alignment layer 44 A and the alignment layer
44B preferably differ from each other by 90 degrees. By arranging these alignment layers 44A and 44B, the direction of alignments of the liquid crystal compounds in the polymerizable liquid crystal compounds of the second anisotropic layers 43A and 43B can differ from each other by 90 degrees. (Optical Compensatory Element according to Fifth Configuration)
FIG. 5 is a sectional view schematically showing an optical compensatory element according to the fifth configuration of the present invention.
The optical compensatory element according to the fifth configuration comprises the first optically anisotropic layer and the second anisotropic layer on at least one surface of the support.
With reference to FIG. 5, optical compensatory element 50 according to the fifth configuration comprises alignment layer 54, second optically anisotropic layer 53, first optically anisotropic layer 52 and antireflective layer 55B arranged in this order on one surface of support 51, so that the antireflective layer 55B constitutes an outermost surface, and comprises antireflective layer 55 A on the opposite surface of the support 51.
The first optically anisotropic layer 52 can have a similar structure to that of the first optically anisotropic layer 2 the optical compensatory element 10 according to the first configuration. Two plies of the optical compensatory element 50 according to the fifth configuration can be used as a laminate. In this case, rubbing directions of the alignment layers in the respective optical compensatory elements preferably differ from each other by 90 degrees.
(Optical Compensatory Element according to Sixth Configuration) FIG. 6 is a sectional view schematically showing an optical compensatory element according to the sixth configuration of the present invention.
The optical compensatory element according to the sixth configuration comprises two second optically anisotropic layers having different direction of alignments. With reference to FIG. 6, optical compensatory element 60 according to the sixth configuration comprises alignment layer 64A, second optically anisotropic layer 63A, alignment layer 64B, second optically anisotropic layer 63B, first optically anisotropic layer 62, and antireflective layer 65B arranged in this order on one surface of support 61, so that the antireflective layer 65B constitutes an outermost layer, and comprises antireflective layer 65A on the opposite surface of the support 61.
The first optically anisotropic layer 62 can have a similar structure to that of the first optically anisotropic layer 2 in the optical compensatory element 10 according to the fist configuration.
The rubbing directions of the alignment layer 64A and the alignment layer 64B preferably differ from each other by 90 degrees. By arranging these alignment layers 64A and 64B, the direction of alignments of the liquid crystal compounds in the polymerizable liquid crystal compounds of the second anisotropic layers 63A and 63B can differ from each other by 90 degrees.
(Optical Compensatory Element according to Seventh Configuration) FIG. 7 is a sectional view schematically showing an optical compensatory element according to the seventh configuration of the present invention.
The optical compensatory element according to the seventh configuration comprises two second anisotropic layers having different direction of alignments arranged with the interposition of the support. With reference to FIG. 7, optical compensatory element 70 according to the seventh configuration comprises alignment layer 74A, second optically anisotropic layer 73A, first optically anisotropic layer 72, and antireflective layer 75B arranged in this order on one surface of support 71, so that the antireflective layer 75B constitutes an outermost surface, and comprises alignment layer 74B, second optically anisotropic layer 73B, first optically anisotropic layer 72, and antireflective layer 75 A arranged in this order on the opposite surface of the support 71,, so that the antireflective layer 75 A constitutes another outermost surface.
The first optically anisotropic layer 72 can have a similar structure to that of the first optically anisotropic layer 2 in the optical compensatory element 10 according to the first configuration. The element may only to comprise at least one first optically anisotropic layer 72, and one of the two first optically anisotropic layers 72 can be omitted.
The rubbing directions of the alignment layer 74A and the alignment layer
74B preferably differ from each other by 90 degrees. By arranging these alignment layers 74 A and 74B, the direction of alignments of the liquid crystal compounds in the polymerizable liquid crystal compounds of the second anisotropic layers 73A and 73B can differ from each other by 90 degrees.
(Optical Compensatory Element according to Eighth Configuration)
FIG. 8 is a sectional view schematically showing an optical compensatory element according to the eighth configuration.
The optical compensatory element according to the eighth configuration comprises the first optically anisotropic layer on one surface of the support and the second optically compensatory layer on the opposite surface of the support.
With respect to FIG. 8, optical compensatory element 80 according to the eighth configuration comprise alignment layer 84, second optically anisotropic layer
83, and antireflective layer 85B arranged in this order on one surface of support 81, so that the antireflective layer 85B constitutes an outermost layer, and comprises first optically anisotropic layer 82 and antireflective layer 85A arranged in this order on the opposite surface of the support 81, so that the antireflective layer 85A constitutes another outermost layer.
The first optically anisotropic layer 82 can have a similar structure to that of the first optically anisotropic layer 2 in the optical compensatory element 10 according to the first configuration.
Two plies of the optical compensatory element 80 according to the eight configuration can be used as a laminate. In this case, rubbing directions of the alignment layers in the respective optical compensatory elements preferably differ from each other by 90 degrees.
In the optical compensatory elements, the optical properties of the first optically anisotropic layers 2, 22, 32, 42, 52, 62, 72 and 82 are determined depending on the pitch of alternative structure of the alternatively multilayered structures comprising inorganic materials. Therefore, these optical compensatory elements can avoid optical ununiformity such as variation of refractive index or reduced haze in a surface of a polymer film which is induced due to residual stress when the polymer film is uniaxially stretched to yield predetermined optical properties, and can have highly uniform optical properties in the surface of the first optically anisotropic layer to thereby optically compensate the liquid crystal layer under a condition for displaying black more precisely.
The first optically anisotropic layers 2, 22, 32, 42, 52, 62, 72, and 82 can be controlled in their in-plane thickness within a range of ten and several nanometers, can have high smoothness and can have higher optical uniformity in their surfaces. The optical compensatory elements thereby can optically compensate the liquid crystal layer under a condition for displaying black more precisely and can reduce light leakage and prevent streaky unevenness.
In addition, the first optically anisotropic layers 2, 22, 32, 42, 52, 62, 72, and 82 do not swell or shrink even in use at high temperature and humidity over a long period of time.
The above-mentioned optical compensatory elements as a whole can minimize changes in optical properties over a long period of time and their durability are remarkably improved. In particular, the optical compensatory elements according to the first, second, and third configurations have the first optically anisotropic layers 2, 22, and 32 on or above the supports 1, 21, and 31, and the in-plane thickness of these first optically anisotropic layers can be controlled within a range of ten and several nanometers. Thus, the first optically anisotropic layers 2, 22, and 32 can prevent unevenness in the in-plane thickness with a high degree of precision and have highly smooth surfaces. Since the second optically anisotropic layers 3, 23, and 33 are arranged adjacent to the first optically anisotropic layers 2, 22, and 32 having such highly smooth surfaces, theses second optically anisotropic layers can be prevented from in-plane alignment failure. The resulting optical compensatory elements can optically compensate the liquid crystal layer under a condition for displaying black more precisely, prevent light leakage at a wide viewing angle and be usable typically in large-screen liquid crystal monitors and liquid crystal projectors which require a wide viewing angle. The resulting liquid crystal displays and liquid crystal projectors can provide high-quality images at high contrast. (Liquid Crystal Display)
The liquid crystal display according to the present invention comprises a pair of electrodes, a liquid crystal device having a liquid crystal compound in which the liquid crystal device is encapsulated in between the pair of electrodes, an optical compensatory element arranged on or above any one of the light incident surface and the light output surface of the liquid crystal device or both of the surfaces, a polarizing element facing the liquid crystal device and the optical compensatory element, and further comprises other elements in accordance with the intended use, and the optical compensatory element is the optical compensatory element according to the present invention.
The displaying mode of the liquid crystal device is not particularly limited, may be suitably selected in accordance with the intended use, and includes, for example, TN (Twisted Nematic) mode, VA (Vertical Alignment) mode, IPS (In-Plane Switching) mode, OCB (Optically Compensatory Bend) mode, and ECB (Electrically Controlled Birefringence) mode, of which TN mode is preferable because of its high contrast ratio.
< Method for Manufacturing Optical Compensatory Element >
The method for manufacturing an optical compensatory element according to the present invention is not particularly limited, may be suitably manufactured in accordance with the intended use, and includes, for example, a first optically anisotropic layer-forming step, an alignment layer-forming step, a second optically anisotropic layer-forming step, a heat treatment step, a second optically anisotropic layer-polymerizing and curing step, an antireflective layer-forming step, and other layers-forming step. The respective layer-forming steps will be described in detail below.
- Forming of First Optically Anisotropic Layer -
The first optically anisotropic layer-forming step is not particularly limited and may be selected in accordance with the intended use, as long as the layer satisfies optical properties. For example, an optically anisotropic layer is formed by laminating plural layers having different refractive indices on or above the support in a regular order in a direction normal to the support, and forming an alternative structure of the alternatively multilayered structures in which the plural layers are repeatedly arranged (a repeating unit is repeated).
Materials of the alternatively multilayered structure is not particularly limited, may be suitably selected in accordance with the intended use, as long as they are inorganic materials, and are preferably used in combination with materials having high refractive indices or low refractive indices.
For materials having high refractive indices, Tiθ2, Zrθ2 and the like are preferred, and for materials having low refractive indices, SiO2, MgF2 and the like are preferred. Each of these materials may be used alone or in combination of two or more.
Specifically, the materials of the alternatively multilayered structure are preferably selected from combinations of materials in which the difference between the maximum refractive index and the minimum refractive index of light in visible region is preferably 0.5 or more, more preferably selected from combinations of a plurality of materials suitably selected from oxides, and particularly preferred to be combinations of SiO2 (refractive index n = 1.4870 to 1.5442) with TiO2 (refractive index n = 2.583 to 2.741).
The number of layers constituting one repeating unit is not particularly limited, as long as the layers are two or more layers each of which has a different refractive index. The layers are preferred to have two or more layers made from two types of inorganic materials, and it is more preferred, for example, that an alternatively multilayered structure comprising ten and several layers is formed by alternatively depositing SiO2 and TiO2 on or above the support under reduced pressure by using a sputtering apparatus.
An optical thickness of the repeating unit, i.e., a thickness of a repeating unit in a laminating direction of the alternatively multilayered structure is preferred to be formed less than the wavelengths of light in the visible region. For example, when the wavelengths of light in the visible region is λ, it is preferably λ/100 to λ/5, more preferably λ/50 to λ/5, and particularly preferably λ/30 to λ/10.
The thickness of the respective layers constituting the alternatively multilayered structure is preferable to be thin, and the number of laminating times is increased for obtaining a required total thickness. Therefore, when determining the number of laminating times of respective layers, it is preferred that the alternatively multilayered structure is formed so that each of the layers has an optimum thickness, by adjusting materials of respective layers, refractive indices, thickness ratio, the total thickness, in consideration of the required optical properties of the first optically anisotropic layer and resultant coloring due to mutual interference of the layers. For instance, the total thickness of the alternatively multilayered structure is preferably selected from 400nm to 700nm.
The thickness of the first optically anisotropic layer is not particularly limited, may be selected in accordance with the intended use and is preferably formed so as to be lOOμm to l,500μm. - Forming of Alignment Layer - In the alignment layer forming step, a layer for serving to determine the alignment direction of the liquid crystal compound in the second optically anisotropic layer is formed on or above the fist optically anisotropic layer.
The alignment layer is not particularly limited, may be suitably selected in accordance with the intended use and includes, for example, a rubbed alignment layer comprising an organic compound (preferably a polymer); an alignment layer having a micro groove; an alignment layer comprising an organic compound, such as tricosanoic acid, dioctadecyldimethylammonium chloride or methyl stearate, deposited according to a Langmuir-Blodgett method (LB film); an alignment layer comprising an inorganic compound deposited by oblique vapor deposition; and an alignment layer having an aligning function as a result of the application of an electric or magnetic field, or light. Among them, the rubbed alignment layer comprising an organic compound is preferred.
The rubbing can be carried out by any procedure selected in accordance with the intended use. For example, the surface of the film comprising an organic compound is rubbed with paper or cloth several times in a certain direction. The organic compound is not particularly limited, may be suitably selected in accordance with the alignment condition of the liquid crystal compound
(particularly the angle of alignment) and includes, for example, a polymer for an alignment layer which does not reduce the surface energy of the resulting alignment layer, for horizontal alignment of the liquid crystal compound.
The preferred examples of the polymer for an alignment layer for aligning the liquid crystal compound in a direction perpendicular to the direction of rubbing are modified polyvinyl alcohols, acrylic copolymers, polyimides, and polyamic acid. Polyimides which are excellent in alignment properties are more preferred. The thickness of the alignment layer is not particularly limited, may be suitably selected in accordance with the intended use, is preferably O.Olμm to 5μm, and more preferably 0.02μm to 2μm. - Forming of Second Optically Anisotropic Layer -
In the second optically anisotropic layer forming step, an optically anisotropic layer using at least a polymerizable liquid crystal composition is formed on the alignment layer.
A solution of the polymerizable liquid crystal composition having the liquid crystal compound is applied to the alignment layer to form a coated layer. The solution is applied using, for example, a wire bar coating, a gravure coating, a micro gravure coating, and a dye coating.
From the perspective of reducing uneven dryness by minimizing the coated amount of a wet solution, a micro gravure coating and a gravure coating are preferred, while from the perspective of uniform thickness in a lateral direction and uniform thickness in a longitudinal direction with time since being coated, a rotating gravure coating is more preferred. The coating of the solution can be carried out with reference to "Research Disclosure, Vol.200" (XV section of Item 20036, December, 1980).
The polymerizable liquid crystal composition of the present invention preferably has a viscosity of 2cP to 3OcP at 20°C and more preferably 3cP to 25cP from the perspective of handing for coating and the like. The preferred range of viscosity slightly varies depending on the way the polymerizable liquid crystal compound is handled. When a large amount of shearing force is applied, as in a spin-coating method, it is preferred to set the viscosity to slightly higher than usual to minimize effect of shearing force. As a coating apparatus of the solution, a blade coater, a rod coater, a knife coater, a roll doctor coater, a reverse roll coater, a transfer roll coater, a gravure coater, a kiss roll coater, a curtain coater, and extrusion coater can be used. Among them, a spin-coater, a slit-coater, and a blade coater are preferably used, and a spin-coater is particularly preferable. The above-noted coating methods can be preferably used, because the coating solution comprising the solvent according to the present invention is relatively stable to shearing force.
The polymerizable liquid crystal compound is not particularly limited and may be suitably selected in accordance with the intended use. For example, a polymerizable liquid crystal compound comprising a liquid crystal compound capable of fixing an alignment condition is preferably used, and a polymerizable composition comprising a liquid crystal compound such as a rod-shaped liquid crystal compound, a discotic structural liquid crystal compound or a banana-shaped liquid crystal compound is more preferable, and a polymerizable composition comprising a discotic structural liquid crystal compound is particularly preferable. The polymerizable liquid crystal compound can include other components suitably selected in accordance with the intended use.
Examples of the other components include a polymerization initiator for starting a polymerization reaction of the polymerizable liquid crystal compound, and a solvent for preparing a coating solution for a polymerizable liquid crystal compound.
- Heat Treatment -
In the heat treatment, a second optically anisotropic layer is heated to form the alignment uniformly and mature the alignment to be maintained. The coated layer is heated at 60°C to 1200C to volatilize and dry the solvent.
After drying the solvent, in order to mature the alignment of the polymerizable liquid crystal composition comprising the liquid crystal compound, the heating temperature is controlled in a range of 85°C to 180°C or until the liquid crystal compound shows a ND layer, ultraviolet rays with an amount of energy full enough to perform a curing reaction are irradiated to the polymerizable liquid crystal compound to polymerize and fix the polymerizable liquid crystal compound comprising the liquid crystal compound to thereby yield an optically anisotropic layer.
- Polymerizing/ Curing of Second Optically Anisotropic Layer - In the polymerizing and curing of the second optically anisotropic layer, the second optically anisotropic layer is polymerized and cured while keeping the above-noted transition temperature.
The polymerizing and curing of the second optically anisotropic layer with the alignment matured is not particularly limited and may be suitably selected in accordance with the intended use as long as the alignment of the liquid crystal layer can be fixed. For instance, a curing reaction of the second optically anisotropic layer is performed by irradiating active rays for photopolymerization.
The active rays for photopolymerization can be suitably selected from electron beam, ultraviolet rays, visible beam, infrared rays (heat rays), in accordance with the intended use. Typically, ultraviolet rays are preferred. Examples of the light source for ultraviolet rays include low pressure mercury lamps (bactericidal lamp, fluorescent chemical lamp, and blacklight lamp), high voltage discharge lamps
(high-pressure mercury lamp, and metal halide lamp), and short arc discharge lamps (ultra-high pressure mercury lamp, xenon lamp, and mercury xenon lamp). Examples of radical polymerization initiators for polymerization reaction of ethylene-unsaturated groups include azobis compounds, peroxides, hydro peroxide, redox catalysts, such as, potassium persulfate, ammonium persulfate, tert-butyl per octoate, benzoyl peroxide, isopropyl per carbonate, 2, 4-dichlobenzoyl peroxide, methyl ethyl ketone peroxide, cumene hydroperoxide, dicumyl peroxide, azobis isobutylonitril, 2,2'-azobis (2-amidinopropane) hydrochroride or benzophenones, acetophenones, benzoins, and thioxanthenes. Details of these . radical polymerization initiators are described in "Ultraviolet curable system"
(Shigaisen-kouka system, pp. 63-147, 1989 by General Technical Center (Sogo
Gijutsu Center)). General examples of a ultraviolet ray-activated cationic catalyst used for polymerization of a compound having epoxy groups include allyl diazonium salt (hexafluorophosphate, tetrafluoroborate, and the like), diallyl iodonium slat, allylonium salt of VIa-groups (allyl sulfonium salt having anion, such as, PF6, AsF6, and SbF6, and the like). When a curing reaction is performed using a radical reaction, to avoid delay in polymerization reaction due to the presence of oxygen in the air, irradiating the above-mentioned active rays in a nitrogen atmosphere is preferable in that the reaction time can be shortened with a small amount of light. - Forming of Antireflective Layer - In the forming of the antireflective layer, an antireflective layer is formed on or above the cured second optically anisotropic layer. For instance, when an inorganic material is used, an antireflective layer is formed on or above a second optically anisotropic layer by a vapor deposition method, and when an organic material is used, an antireflective layer is formed by a coating method. The deposition is not particularly limited and can be carried out by any method in accordance with the intended use. The deposition is carried out, for example, by a chemical vapor deposition (CVD) method in which a sample is left in a gas atmosphere to form a layer on the surface of the sample by chemical reaction, and a physical vapor deposition (PVD) method in which raw materials in a state of particles are physically attached to a sample to form a layer.
Among them, a physical vapor deposition (PVD) method in which a layer is physically prepared by sputtering a sputtering target formed with a metal being a material for the antireflective layer under reduced pressure is preferably used.
The coating is not particularly limited, can be coated by any procedure in accordance with the intended use, and the antireflective layer is formed by, for example, a wire bar coating, a gravure coating, a micro gravure coating, and a dye coating. From the perspective of reducing uneven dryness by minimizing the coated amount of a wet solution, a micro gravure coating and a gravure coating are preferred, while from the perspective of uniform thickness in a lateral direction and uniform thickness in a longitudinal direction with time since the coating, a rotating gravure coating is more preferred.
- Forming of Other Layers -
In the forming of other layers, the individual steps from the forming of the first optically anisotropic layer, the forming of the alignment layer, the forming of the second optically anisotropic layer, the heat treatment to the polymerizing and curing of the second optically anisotropic layer are repeated at least once more in this order, and the forming of other layers includes forming of another second optically anisotropic layer in which the another second optically anisotropic layer having a different direction of alignment from that of the optically anisotropic layer previously formed.
Other layers can be arbitrarily formed before or after forming the antireflective layer. For example, a protective layer, an antiglare-layer, antif ouling layer, and an antistatic layer can be formed.
- Forming of Protective Layer - The forming of the protective layer is a step for forming a protective layer, is not particularly limited, may be suitably selected in accordance with the intended use. For instance, it is preferred that in the polymerizing and curing of second optically anisotropic layer, the second optically anisotropic layer is first polymerized and cured to fix the alignment of the liquid crystal layer and then a protective layer is arranged on the second optically anisotropic layer. The protective layer is a layer for blocking oxidation reaction of the second optically anisotropic layer comprising an organic material to improve durability and is preferably disposed on the second optically anisotropic layer.
The method for disposing the protective layer is not particularly limited and may be selected in accordance with the intended use. When an organic material is used/ for example, a preferred method is that a solution for forming a protective layer is formed and then coated on the second optically anisotropic layer for lamination.
The coating method is not particularly limited and includes, for example, an extrusion coating, a direct gravure coating, a reverse gravure coating, a dye coating, and a spin-coating.
When an inorganic material is used, the protective layer is preferably formed, for example, by a deposition method, Le., by depositing the material.
The deposition method is not particularly limited and may be suitably selected in accordance with the intended use. Examples of the deposition method include a chemical vapor deposition (CVD) process in which a sample is left in a gas material atmosphere to form a thin layer on the surface of the sample by chemical reaction, and a physical vapor deposition (PVD) process in which raw materials in a state of particles are attached to the surface of the sample by vapor deposition or sputtering to form a thin layer.
Among them, a physical vapor deposition process that a layer is physically prepared by sputtering a sputtering target formed with a metal being a material for the protective layer under reduced pressure, is more preferable. (Liquid Crystal Display) A liquid crystal display according to the present invention comprises one pair of electrodes and a liquid crystal device having liquid crystal molecules encapsulated in between the at least one pair of electrodes, an optically anisotropic layer arranged on or above any one of the light incident surface and the light output surface of the liquid crystal device or both of the surfaces, and one polarizing element facing the liquid crystal device and the optically anisotropic layer and further comprises other configurations in accordance with the intended use, in which the optically anisotropic layer is an optically anisotropic layer according to the present invention.
The displaying mode of the liquid crystal device is not particularly limited, may be suitably selected in accordance with the intended use, and includes, for example, TN (Twisted Nematic) mode, VA (Vertical Alignment) mode, IPS (In-Plane Switching) mode, OCB (Optically Compensatory Bend) mode, and ECB (Electrically Controlled Birefringence) mode. Among them, TN mode is particularly preferable because of its high contrast ratio. FIGs. 9 to 12 are respectively schematic diagrams showing the liquid crystal displays of the present invention.
To promote better understanding, in the schematic diagrams of the liquid crystal displays in the drawings, light emitted from a light source comes into the liquid crystal display from lower side of the drawings and is irradiated toward upper side of the drawings. When the polarizing plate and/or the second optically anisotropic layer comprises two components, the one that is present in the. upper side of the drawings is called as "upper" component, and the other present in the lower side in the drawings is called as "lower" component.
With reference to FIG. 9, liquid crystal display 100 comprises upper polarizing element 101 (analyzer) and lower polarizing element 116 (polarizer) which are a pair of polarizing elements, wave plate 108 arranged between the upper and lower polarizing elements 101 and 116 and liquid crystal device 114 (liquid crystal cell).
Polarization beam splitters such as Glan-Thompson prisms may be arranged as the polarizing element instead of the upper and lower polarizing elements 101 and 116 so as to sandwich the liquid crystal device 114.
The liquid crystal device 114 comprises an upper substrate 109 and lower substrate 113 each of which comprises a glass substrate and arranged so as to face each other, and nematic liquid crystal 111, for example, encapsulated in between these upper and lower substrates 109 and 113. The upper substrate 109 and the lower substrates 113 have components (not shown) such as picture electrodes and circuit elements (thin-film transistors) on their surfaces facing each other. The upper substrate 109 and the lower substrate 113 further have upper and lower alignment layers (not shown), respectively, on their surfaces adjacent to the nematic liquid crystal 111. The surfaces of the alignment layers adjacent to the nematic liquid crystal 111 have been rubbed for aligning the directions of alignment of liquid crystal molecules. The directions of rubbing 110 and 112 in the upper and lower alignment layers, i.e., the direction of grooves formed as a result of rubbing are substantially perpendicular to each other, for example, in the case of a liquid crystal display of a TN mode.
FIG. 10 illustrates the arrangement of liquid crystal molecules under a normal condition where no voltage is applied to the liquid crystal device 114. Liquid crystal molecules in the nematic liquid crystal 111 near to the upper substrate 109 and to the lower substrate 113 are arranged in directions substantially identical to the directions of rubbing 110 and 112 by the action of rubbing on the alignment layers (not shown). Thus, the liquid crystal molecules in the nematic liquid crystal 111 are aligned so as to have major axes, whose directions are twisted by 90 degrees from the upper substrate 109 toward the lower substrate 113, since the directions of rubbing 110 and 112 are perpendicular to each other. The optical transmittance of the polarizing elements in a cross nicol arrangement is preferably 0.001% or less, provided that the optical transmittance of the polarizing elements in a parallel nicol arrangement is defined as 100%.
The upper polarizing element 101 (analyzer) and the lower polarizing element 116 (polarizer) each comprises a polarizing film and may further comprise any other components in accordance with the intended use.
The polarizing film is not particularly limited, may be suitably selected in accordance with the intended use and includes, for example, a stretched film made from a hydrophilic polymer which has adsorbed a dichroic material and has been subjected to stretching for alignment. Examples of the hydrophilic polymer are polyvinyl alcohols, partially formalized polyvinyl alcohols, and partially saponified products of ethylene-vinyl acetate copolymers. Examples of the dichroic material are iodine and dichroic dyes such as azo dyes, anthraquinone dyes, and tetrazine dyes.
The stretching procedure can be carried out by using any device suitably selected in accordance with the intended use, such as a lateral uniaxial tenter stretching machine in which the adsorption axis of the polarizing film is substantially perpendicular to the longitudinal direction. The lateral uniaxial tenter stretching machine is advantageous in that it can avoid foreign matter entering during lamination. A stretching method described in JP-A No. 2002-131548 can be employed in the stretching for alignment.
The other components are not particularly limited, can be suitably selected in accordance with the intended use and includes, for example, a protective layer, an antireflective layer, and an anti-glare layer each arranged on or above at least one surface of the polarizing firm. Each of the upper and lower polarizing elements 101 and 116 is preferably a polarizing plate having the protective layer on at least one surface of the polarizing film having an integrated article comprising the liquid crystal device 114 as a support on one surface of the liquid crystal device 114. The material for the protective layer is not particularly limited, may be suitably selected in accordance with the intended use and includes, for example, cellulose esters such as cellulose acetate, cellulose acetate butyrate and cellulose propionate; polycarbonates; polyolefins; polystyrenes; and polyesters.
Suitable examples of the material for the protective layer are cellulose triacetate, and polyolefins such as ZEONEX and ZEONOR (both manufactured by NIPPON ZEON CO., LTD.), and ARTON (manufactured by JSR Corporation).
Non-birefringent optical resin materials described in JP-A No. 08-110402 and JP-A No. 11-293116 can be used herein.
The alignment axis (slow axis) of the protective layer is arranged in any direction but is preferably in parallel with the longitudinal direction for easy and convenient operation. The angle formed between the slow axis (alignment, axis) of the protective layer and the adsorption axis (stretching axis) of the polarizing film is not particularly limited and may be suitably set in accordance with the target polarizing plate. When the polarizing film is prepared by using the lateral uniaxial tenter stretching machine, the slow axis (alignment axis) of the protective layer is in a direction substantially perpendicular to the adsorption axis (stretching axis) of the polarizing film.
The retardation of the protective layer is not particularly limited, may be suitably selected set in accordance with the intended use and is preferably, for example, lOnm or less and more preferably 5nm or less when measured by light having a wavelength of 632.8 ran.
The retardation of the cellulose acetate, if used, is preferably less than 3nm and more preferably 2nm or less for rninirnizing a variation of the retardation with temperature and humidity in the environment. The polarizing plate can be prepared by any method suitably selected in accordance with the intended use and is preferably prepared by continuously laminating onto a long polarizing film fed as a roll so that the longitudinal directions meet each other.
The polarizing film and the polarizing plate are preferably fixed to the liquid crystal device for preventing misregistration of the optical axis and for preventing foreign matter such as dust from entering.
The antireflective layer is not particularly limited, may be suitably selected in accordance with the intended use and includes, for example, a coating layer of a fluorine-containing polymer, and an optical interference layer such as a multilayered metal layer prepared by vapor deposition.
The upper and lower polarizing elements 101 and 116 preferably have optical properties and durability (short-term and long-time storage stability) equal to or higher than those of a commercially available high-contrast product, such as HLC2-5618 manufactured by Sanritz Corporation. The optical compensatory element 108 comprises the optical compensatory element according to the present invention.
When the optical compensatory element is integrated into the liquid crystal display 100, the contrast ratio Vw/ Vb in front of the liquid crystal display 100 is preferably 100:1 or more, more preferably 200:1 or more, and particularly preferably 300:1 or more. The contrast ratio is the ratio of the transmittance of the liquid crystal display 100 in displaying white "Vw" to the transmittance in displaying black "Yb".
The maximum transmittance in displaying black is preferably 10% or less, and more preferably 5% or less of Vw in an azimuth direction inclined 60 degrees from the normal direction to the display surface of the liquid crystal display 100. By using the optical compensatory element having such properties, the resulting liquid crystal display exhibits a high contrast and a wide viewing angle without tone reversal.
To accurately compensate a liquid crystal device having a large residual twisted component, the liquid crystal display preferably does not optically quench in any direction and has an optical transmittance of 0.01% or more in all directions when the optical compensatory element is arranged between a pair of polarizing elements arranged in a cross nicol manner, and the optical compensatory element is rotated in the normal direction to the optical compensatory element as a rotation axis.
The optical compensatory element 108 is arranged between the upper polarizing element 101 and the liquid crystal device 114 and comprises a first optically anisotropic layer 107, an upper second optically anisotropic layer 103 and a lower second optically anisotropic layer 105. The respective optically anisotropic layers constituting the optical compensatory element 108 are arranged so that the angle formed between the rubbing direction 104 of an alignment layer in the upper second optically anisotropic layer 103 and a direction of rubbing 110 of an upper alignment layer in an upper substrate 109 of the liquid crystal device 114 is 180° and so that a direction of rubbing 106 of an alignment layer in the lower second optically anisotropic layer 105 and a direction of rubbing 112 of a lower alignment layer in a lower substrate 113 of the liquid crystal device 114 is 180°.
The directions of rubbing in the alignment layers in the second optically anisotropic layer and in the substrate of the liquid crystal device may be exchanged. More specifically, the layers may be arranged so that the angle formed between the direction of rubbing 106 of the alignment layer in the lower second optically anisotropic layer 105 and the direction of rubbing 110 of the upper alignment layer in the upper substrate 109 of the liquid crystal device 114 is 180° and so that the angle formed between the direction of rubbing 104 of the alignment layer in the upper second optically anisotropic layer 103 and ihe direction of rubbing 112 of the lower alignment layer in the lower substrate 113 of the liquid crystal device 114 is 180°.
The first optically anisotropic layer 107 is preferably arranged near to the liquid crystal device 114. FIG. 11 schematically illustrates the arrangement of liquid crystal molecules in a liquid crystal display of a TN mode under a condition for displaying black , i.e., when a voltage is applied to the liquid crystal device 114. Upon application of a voltage to the liquid crystal device 114, the liquid crystal molecules change in their arrangement so that the liquid crystal molecules stand up with their major axes perpendicular to the incident plane of light. Ideally, all the liquid crystal molecules in the liquid crystal device 114 should preferably stand perpendicular to the incident plane of light upon application of a voltage. In actuality, however, the major axis of the liquid crystal molecules in the liquid crystal device 114 gradually become perpendicular to the incident plane of light from the upper substrate 109 and the lower substrate 113 toward the center part of the liquid crystal device 114, as shown in FIG. 11. Thus, liquid crystal molecules in the vicinity of the interfaces of the upper substrate 109 and of the lower substrate 113 are arranged so that their major axes are not parallel with but oblique or inclined to the incident plane of light even upon application of a voltage. These liquid crystal molecules being inclined to the incident plane of light fail to display black and cause light leakage at some viewing angles.
In addition, nematic liquid crystal molecules for use in such a liquid crystal display of a TN mode are generally rod-shaped liquid crystal molecules and exhibit optically positive uniaxial properties. Accordingly, when the liquid crystal display 100 is viewed from an oblique direction, even the liquid crystal molecules at the center part of the liquid crystal device 114 stand up completely perpendicular to the incident direction of light cause birefringence, birefringence, and the liquid crystal device fails to display black and cause light leakage at some viewing angles.
The birefringence caused by the alignment of the liquid crystal molecules in the liquid crystal device 114 in the vicinity of the upper substrate 109 and of the lower substrate 113 under a condition for displaying black can be optically compensated by allowing the alignment of the liquid crystal molecules in the second optically anisotropic layers 103 and 105 to be mirror symmetry. In addition, the birefringence caused by liquid crystal molecules at the center part of the liquid crystal device 114 can be optically compensated by arranging the first optically anisotropic layer 107 having optical properties as a not-inclined uniaxial ellipsoid having a negative refractive index. Thus, the liquid crystal device 114 under a condition for displaying black can be optically compensated three-dimensionally in totality to thereby prevent light leakage in a wide range of viewing angles. The optical compensate element 108 can be arranged under the liquid crystal device 114, as shown in FIG. 11, or can be arranged on or above any one of the light incident surface and the light output surface of the liquid crystal device 114 as optical compensate elements 108a and 108b, as shown in FIG. 12. When the optical compensate elements 108a and 108b are arranged on and under the optical crystal element 114, one of first optically anisotropic layers 107a and 107b can be omitted. When both the first optically anisotropic layers 107a and 107b are arranged, the retardation is defined as a total of the retardations of these layers.
The optical compensatory element 108 can have the upper substrate 109 and the lower substrate 113 of the liquid crystal device 114 as the substrate (not shown) equipped to the optical compensatory element 108. In this case, the first optically anisotropic layers 107a and 107b shown in FIG. 12 are directly arranged on the upper substrate 109 and the lower substrate 113, respectively. (Liquid Crystal Projector)
The liquid crystal projector according to the present invention is so configured that light from a light source is applied to a liquid crystal display to allow the liquid crystal display to optically modulate the light, and the modulated light is allowed to form an image on a screen by the action of a projection optical system so as to display the image, in which the liquid crystal display is the liquid crystal display of the present invention. The type of the liquid crystal projector is not particularly limited, may be suitably selected in accordance with the intended use and includes, for example, a screen-projection front projector and a rear-projection television set. The type of the liquid crystal display is not particularly limited and may be suitably selected in accordance with the intended use. Preferred examples thereof include a transmission liquid crystal display and a reflective liquid crystal display. FIG. 13 is an outside view schematically illustrating a rea-projection liquid crystal projector.
With reference to FIG. 13, liquid crystal projector 200 comprises a diffusional transmittance screen 203 in front of housing 202. An image projected to the rear of the screen 203 is viewed from the front of the screen 203. Housing 202 houses a projection unit 300, and an image projected by the projection unit 300 is reflected by mirrors 206 and 207 to form an image on the rear side of the screen 203. Housing
202 of the liquid crystal projector 200 also houses other components (not shown) such as a tuner circuit and circuit units for reproducing video signals and voice signals.
The projection unit 300 includes a liquid crystal display (not shown) as an image display device. The liquid crystal display serves to display a reproduced image of the video signal to thereby display an image projected on the screen 203.
FIG. 14 is a schematic diagram illustrating a projection unit 300. With reference to FIG. 14, the projection unit 300 comprises three liquid crystal devices 311R, 311G, and 311B, and can project full-color images.
Light emitted from a light source 312 pass through a filter 313 for cutting ultraviolet rays and infrared rays, becomes white light including red light, green light, and blue light and comes into a glass rod 314 along an optical axis from the light source 312 to the liquid crystal devices 311R, 311G, and 311B. The incident plane of light in the glass rod 314 is located in the vicinity of the focus of a parabolic mirror used in the light source 312, and the light from the light source 312 efficiently comes into the glass rod 314.
A relay lens 315 is arranged on a light output surface of the glass rod 314, and the white light going out from the glass rod 314 becomes parallel light by the action of the relay lens 315 and a subsequent collimate lens 316 and conies into a mirror 317.
The white light reflected by the mirror 317 is divided into two luminous fluxes by a dichroic mirror 318R transmitting red light alone, and the transmitted red light is reflected by a mirror 319 to illuminate a liquid crystal device 311R from the back.
The green light and the blue light reflected by the dichroic mirror 318R is further divided into two luminous fluxes by a dichroic mirror 318G reflecting green light alone. The green light reflected by the dichroic mirror 318G illuminates a liquid crystal device 311G from the backside. The blue light passing through the dichroic mirror 318G is reflected by mirrors 318B and 320 to illuminate a liquid crystal device 311B from the back.
Each of the liquid crystal devices 311R, 311G, and 311B comprises a liquid crystal device of a TN mode, and the respective liquid crystal devices display light and dark patterns of a red image, a green image, and a blue image, respectively, to constitute a full-color image. A composite prism 324 is arranged at a position at an optically equal distance from these liquid crystal devices 311R, 311G, and 311B, and a projector lens 325 is arranged so as to face the light output surface of the composite prism 324. The composite prism 324 internally includes two dichroic planes 324a and 324b and serves to composite the red light passing through the liquid crystal device 311R, the green light passing through the liquid crystal device 311G, and the blue light passing through the liquid crystal device 311B to allow the composite light to come into the projector lens 325.
The projector lens 325 is arranged on a projection light axis extending from the centers of light output surfaces of the liquid crystal devices 311R, 311G, and 311B via the centers of the composite prism 324 and the projector lens 325 to the centers of a screen 303. The projector lens 325 is arranged so that its objective focal plane agrees with the light output surfaces of the liquid crystal devices 311R, 311G, and 311B, and its imaging focal plane agrees with the screen 303. Thus, the full-color image composed by the composite prism 324 is allowed to form an image on the screen 303.
Polarizing plates 326R, 326G, and 326B are arranged neat to the incident planes of illuminated light of the liquid crystal devices 311R, 311G, and 311B. Optical compensatory elements 327R, 327G, and 327B and polarizing plates 328R, 328G, and 328B are respectively arranged near to the light output surfaces of the liquid crystal devices 311R, 311G, and 311B. The polarizing plates 326R, 326G, and 326B near to the incident planes are arranged in a cross nicol manner with respect to the polarizing plates 328R, 328G, and 328B near to the light output surfaces. The polarizing plates 326R, 326G, and 326B server as polarizers, and polarizing plates 328R, 328G, and 328B serve as analyzers.
The liquid crystal display according to the present invention comprises the liquid crystal devices 311R, 311G, and 311B; the polarizing planes 326R, 326G, 326B, 328R, 328G, and 328B; and the optical compensatory elements 327R, 327G, and 327B. The operations of the liquid crystal devices for respective color channels, and the polarizing plates and the optical compensatory elements sandwiching these liquid crystal devices are basically same, while there are some differences based on the colored light. The operations will be illustrated below by taking a red channel as an example.
The illuminated red light reflected by the mirror 319 is converted into linearly polarized light by the action of the polarizing plate 326R near to the incident plate and comes into the liquid crystal device 311R. In a normally white mode, a signal voltage is applied to a pixel to thereby allow a liquid crystal of a TN mode used in the liquid crystal device 311R to display black in a red image. In the procedure, liquid crystal molecules in the liquid crystal layer have various postures in their alignment. Thus, an image light outgoing from the light output surface of the liquid crystal device 311R does not become a fully linearly polarized light but an elliptically polarized light because of optical rotation and birefringence of the liquid crystal layer, even if the illuminated red light becomes a parallel pencil and comes into the liquid crystal device 311R. This causes light leakage from the polarizing plate 328R serving as the analyzer and fails to produce full black. In a normally black mode, slight inclination of the liquid crystal molecules causes insufficient black level.
When the light includes a component which passes through the liquid crystal molecules in the liquid crystal device in an oblique direction under a condition for displaying black, the image light modulated by the liquid crystal layer becomes elliptically polarized light having an optical phase slightly different from that of linearly polarized light. This causes light leakage from the polarizing plate 328R serving as the analyzer and fails to yield sufficient black level.
The liquid crystal projector of the present invention comprises the liquid crystal display of the present invention using the optical compensatory element of the present invention. The optical compensatory element 327R serves to optically compensate the liquid crystal layer under a condition for displaying black more precisely and to prevent light leakage at a wide viewing angle.
The liquid crystal projector of the present invention can thereby yield a high-quality image at a high contrast and a wide viewing angle. Examples
The present invention will be described in further detail with reference to several examples below, which are never intended to limit the scope of the present invention. (Example 1)
< Preparation of Coating Solution for Polymerizable Composition >
A coating solution for polymerizable composition comprising the following composition was prepared.
• Liquid crystal compound having a discotic structural unit represented by the following structural formula (3) 4.27g
• Ethylene oxide-modified trimemylolpropanetriacrylate
(V#360, manufactured by Osaka Organic Chemical Industry Ltd.) 0.42g
• Cellulose acetate butylate
(CAB551-0.2, manufactured by Eastman Chemical Company) 0.09g • Cellulose acetate butylate
(CAB531-1, manufactured by Eastman Chemical Company) 0.02g.
• Photopolymerization initiator
(IRGACURE907, manufactured by Ciba-Geigy Chemical Corporation)0.14g
• Sensitizing agent (Kayacure DETX-S, manufactured by Nippon Kayaku Co., Ltd.) 0.05g
• Solvent
(2-(l-methoxypropyl) acetate) (boiling point 145°C) 15.0Og
Figure imgf000074_0001
Structural Formula (3)
< Preparation of Coating Solution for Alignment Layer)
A coating solution for an alignment layer comprising the following composition was prepared.
• Modified polyvinyl alcohol represented by the following structural formula (6) 2Og
• Water (solvent) 36Og
• Methanol 12Og
• Glutaraldehyde (cross-linking agent) Ig
Figure imgf000074_0002
Structural Formula (6)
< Preparation of Optical Compensatory Element > An optical compensatory element having a configuration similar to that of the first configuration illustrated in FIG. 1 was prepared by the following method. As shown FIG.1, an optical compensatory element 10 according to the first configuration of the present invention comprises a support 1; a first optically anisotropic layer 2, an antireflective layer 5A disposed in this order on one surface of the support 1; an alignment layer 4A, a second optically anisotropic layer 3 A, an alignment layer 4B, a second optically anisotropic layer 3B, and an antireflective layer5B formed on the opposite side of the support 1 in this order.
- Formation of First Optically Anisotropic Layer - First, a glass substrate was used as a support 1. A first optically anisotropic layer having an alternately multilayered structure 2 was prepared by depositing layers of Siθ2 and TiO2 in alternate manner on the glass substrate by vapor deposition using a sputtering machine under reduced pressure. Specifically, each twenty-six layers of SiOa and TiO2 were formed, namely, a total of fifty-two layers were formed. The resulting first optically anisotropic layer had a total thickness of 760nm and a retardation Rth of 200nm.
- Formation of Antireflective Layer -
An antireflective layer 5 A was formed on the surface of the first optically anisotropic layer 2 by depositing layers of SiO2 and TiO2 alternately by vapor deposition under reduced pressure using a sputtering machine. The resulting antireflective layer had a thickness of 0.24μm.
- Formation of Alignment Layer -
The obtained coating solution for an alignment layer was added dropwise in an amount of 100ml/ m2 onto the opposite side of the glass substrate on which the first optically anisotropic layer formed and was subjected to spin coating at l,000rpm. The coating solution for an alignment layer was then dried with a hot air at 100°C for three minutes to form an alignment layer 600nm having a thickness of 600nm. The alignment layer was subjected to rubbing process to yield the alignment layer 4A aligned in a predetermined direction of alignment. - Formation and Measurement of Second Optically Anisotropic Layer -
The obtained coating solution for a polymerizable liquid crystal compound was added dropwise to the surface of the alignment layer 4A to an amount of 100ml/ m2 and was subjected to spin coating at l,500rpm, followed by heating in a thermostat zone at 13O0C for 5 minutes to align the polymerizable liquid crystal compound. The polymerized liquid crystal compound was then polymerized to thereby fix the alignment of liquid crystal compound by irradiating ultraviolet rays for 1 minute using a 120W/ cm2 high pressure mercury lamp, followed by gradually cooling to room temperature to thereby yield the second optically anisotropic layer 3A. In the resulting second optically anisotropic layer 3 A, the discotic liquid crystal compound was hybrid aligned, since the angle (angle of alignment) formed by the normal line of the normal axis of the disc surface with the normal line of the glass substrate increases from 10° to 62° from the glass substrate toward the air interface side. The angle of alignment of the discotic liquid crystal compound was determined by determining retardations at a varying observation angle using an ellipsometer (M-150, manufactured by JASCO Corporation), assuming a refractive index ellipsoid model based on the determined retardations and calculating the angle of alignment according to a technique described in "Design Concepts of the Discotic Negative Birefringence Compensation Films SID98 DIGEST". The haze of the optically anisotropic layer 3 A was measured using HGM-2DP (manufactured by SUGA TEST INSTRUMENTS CO., Ltd.). The appearance of surface anomaly was determined visually by using a Color 3D Profile Microscope manufactured by KEYENCE CORPORATION. Table 1 shows the results. Next, on the surface of the second optically anisotropic layer 3A, an alignment layer 4B was further formed so that the direction of alignment of the alignment layer 4B was substantially perpendicular to that of the alignment layer 4A. A second optically anisotropic layer 3B was formed on the surface of the alignment layer 4B in the same manner as in the second optically anisotropic layer 3 A. In the resultant second optically anisotropic layer 3B, the discotic liquid crystal compound was hybrid aligned, since the angle (angle of alignment) formed by the normal line of the normal axis of the disc surface with the normal line of the glass substrate increases from 7° to 60° from the glass substrate toward the air interface side. In addition, the resultant second optically anisotropic layer 3B is homogenous layer without defects such as schlieren. - Formation of Antireflective Layer -
A antireflective layer 5B was formed by depositing layers of Siθ2 and ΗO2 on the surface of the second optically anisotropic layer 3B in alternate manner by vapor deposition using a sputtering machine under reduced pressure. The resultant antireflective layer 6 has a thickness of 0.24μm. (Example IA) < Preparation of Liquid Crystal Display >
A liquid crystal display according to Example IA was prepared by laminating the above-prepared optical compensatory element 10 onto a liquid crystal device of a TN mode in a normally white mode at a voltage to display white of 1.5V and a voltage to display black of 3V.
- Evaluation of Contrast in Liquid Crystal Display -
The contrast of the above-prepared liquid crystal display was determined at a position with an angle of elevation of 60° and an azimuth angle of 30° from the front of the display surface using a conoscope (manufactured by Autronic-Melcher GmbH). The contrast includes illuminance intensities in displaying white and in displaying black and a contrast ratio (illuminance intensity in displaying white/ illuminance intensity in displaying black) determined based on the ratio thereof. Table 1 shows the results. (Example IB)
< Preparation of Liquid Crystal Projector >
Each three liquid crystal displays corresponding to red, green, and blue colors (according to Example IA) was integrated into a liquid crystal projector of a TN mode to yield a liquid crystal projector according to Example IB. - Evaluation of Contrast in Liquid Crystal Projector -
With respect to the liquid crystal projector (according to Example 1B)> the illuminate intensities in displaying white and in displaying black/and the contrast ratio thereof (illuminate intensity in displaying white/ illuminate intensity in displaying black) on the screen set at a distance of 3m from the projector lens were determined. (Example 2)
An optical compensatory element according to Example 2, a liquid crystal display according to Example 2A, and a liquid crystal projector according to Example 2B were prepared in the same manner as in Example 1, IA, and IB, respectively, provided that 15g of 2-(l-methoxypropyl) acetate (boiling point 145°C) included in the polymerizable composition in Example 1 was changed to 15g of
3-methoxy-3-methyl butyl acetate, and were evaluated.
(Example 3)
An optical compensatory element according to Example 3, a liquid crystal display according to Example 3A, and a liquid crystal projector according to Example
3B were prepared in the same manner as in Example 1, IA, and IB, respectively, provided that 15g of 2-(l-methoxypropyl) acetate (boiling point 145°C) included in the polymerizable composition in Example 1 was changed to 2Og of ethyl lactate
(boiling point 154°C), and were evaluated. (Example 4)
An optical compensatory element according to Example 4, a liquid crystal display according to Example 4A, and a liquid crystal projector according to Example
4B were prepared in the same manner as in Example 1, IA, and IB, respectively, provided that 15g of 2-(l-methoxypropyl) acetate (boiling point 145°C) included in the polymerizable composition in Example 1 was changed to 15g of 3-hyroxyethyl butanoicaάd (boiling point 1700C), and were evaluated.
(Example 5)
An optical compensatory element according to Example 5, a liquid crystal display according to Example 5 A, and a liquid crystal projector according to Example 5B were prepared in the same manner as in Example 1, IA, and IB, respectively, provided that 15g of 2-(l-methoxypropyl) acetate (boiling point 145°C) included in the polymerizable composition in Example 1 was changed to 15g of 3-hyroxymethyl butanoic acid, and were evaluated.
(Example 6) An optical compensatory element according to Example 6, a liquid crystal display according to Example 6A, and a liquid crystal projector according to Example 6B were prepared in the same manner as in Example 1, IA, and IB, respectively, provided that 15g of 2-(l-methoxypropyl) acetate (boiling point 145°C) included in the polymerizable composition in Example 1 was changed to 15g of butyl lactate (boiling point 186°C), and were evaluated. (Example 7)
An optical compensatory element according to Example 7, a liquid crystal display according to Example 7A, and a liquid crystal projector according to Example 7B were prepared in the same manner as in Example 1, IA, and IB, respectively, provided that 15g of 2-(l-methoxypropyl) acetate (boiling point 1450C) included in the polymerizable composition in Example 1 was changed to 20.5g of 2-ethoxyethyl propionate, and were evaluated. (Example 8)
An optical compensatory element according to Example 8, a liquid crystal display according to Example 8 A, and a liquid crystal projector according to Example 8B were prepared in the same manner as in Example 1, IA, and IB, respectively, provided that 15g of 2-(l-methoxypropyl) acetate (boiling point 145°C) included in the polymerizable composition in Example 1 was changed to 20.5g of 2-methoxymethyl propionate, and were evaluated. (Example 9)
An optical compensatory element according to Example 9, a liquid crystal display according to Example 9A, and a liquid crystal projector according to Example 9B were prepared in the same manner as in Example 1, IA, and IB, respectively, provided that 15g of 2-(l-methoxypropyl) acetate (boiling point 145°C) included in the polymerizable composition in Example 1 was changed to 20.5g of 3-ethoxyethyl propionate (boiling PoIrItIOo0Q, and were evaluated. (Example 10)
An optical compensatory element according to Example 10, a liquid crystal display according to Example 1OA, and a liquid crystal projector according to Example 1OB were prepared in the same manner as in Example 1, IA, and IB, respectively, provided that 15g of 2-(l-methoxypropyl) acetate (boiling point 145°C) included in the polymerizable composition in Example 1 was changed to 20.5g of 3-methoxymethyl propionate (boiling point 142°C), and were evaluated. (Example 11) An optical compensatory element according to Example 11, a liquid crystal display according to Example HA, and a liquid crystal projector according to Example HB were prepared in the same manner as in Example 1, IA, and IB, respectively, provided that 15g of 2-(l-methoxypropyl) acetate (boiling point 145°C) included in the polymerizable composition in Example 1 was changed to a mixed solution of 16g of 3-ethoxyethyl propionate (boiling point 166°C) and 4g of ethyl lactate (boiling point 154°C), and were evaluated. The viscosity of the polymerizable . composition at a temperature of 20°C is lOcP. (Example 12)
An optical compensatory element according to Example 12, a liquid crystal display according to Example 12A, and a liquid crystal projector according to Example 12B were prepared in the same manner as in Example 1, IA, and IB, respectively, provided that 15g of 2-(l-methoxypropyl) acetate (boiling point 145°C) included in the polymerizable composition in Example 1 was changed to a mixed solution of 12g of 2-ethoxyethyl propionate (boiling point 166°C), 4g of ethyl lactate (boiling point 1540Q and 4g of methyl ethyl ketone (boiling point 8O0Q, and were evaluated. The viscosity of the polymerizable composition at a temperature of 20°C is 7cP. (Example 13)
An optical compensatory element according to Example 13, a liquid crystal display according to Example 13 A, and a liquid crystal projector according to Example 13B were prepared in the same manner as in Example 1, IA, and IB, respectively, provided that 15g of 2-(l-methoxypropyl) acetate (boiling point 145°C) included in the polymerizable composition in Example 1 was changed to a mixed solution of 12g of 3-ethoxyethyl propionate (boiling point 166°Q, 4g of hydroxyethyl butanoic acid and 4g of methyl ethyl ketone (boiling point 80°C), and were evaluated. The viscosity of the polymerizable composition at a temperature of 20°C is 6cP. (Example 14)
An optical compensatory element according to Example 14, a liquid crystal display according to Example 14A, and a liquid crystal projector according to Example 14B were prepared in the same manner as in Example 1, IA, and IB, respectively, provided that 15g of 2-(l-methoxy propyl) acetate (boiling point 145°C) included in the polymerizable composition in Example 1 was changed to a mixed solution of 12g of 3-ethoxyethyl propionate (boiling point 166°Q, 4g of butyl lactate (boiling point 186°C) and 4g of methyl ethyl ketone (boiling point 80°Q, and were evaluated. The viscosity of the polymerizable composition at a temperature of 20°C is 6.5cP. (Example 15)
An optical compensatory element according to Example 15, a liquid crystal display according to Example 15A, and a liquid crystal projector according to Example 15B were prepared in the same manner as in Example 1, IA, and IB, respectively, provided that 15g of 2-(l-methoxypropyl) acetate (boiling point 145°C) included in the polymerizable composition in Example 1 was changed to a mixed solution of 12g of 3-ethoxyethyl propionate (boiling point 1660C), 4g of 3-hydroxymethyl butanoic acid and 2g of acetone, and were evaluated. The viscosity of the polymerizable composition at a temperature of 20°C is 6cP. (Example 16) An optical compensatory element according to Example 16, a liquid crystal display according to Example 16A, and a liquid crystal projector according to Example 16B were prepared in the same manner as in Example 1, IA, and IB, respectively, provided that 15g of 2-(l-methoxypropyl) acetate (boiling point 145°C) included in the polymerizable composition in Example 1 was changed to a mixed solution of 12g of 3-ethoxyethyl propionate (boiling point 166°C), 4g of ethyl lactate and 4g of 2-(l-methoxypropyl) acetate (boiling point 145°C), and were evaluated. The viscosity of the polymerizable composition at a temperature of 20°C is 6cP. (Example 17)
An optical compensatory element according to Example 17, a liquid crystal display according to Example 17A, and a liquid crystal projector according to Example 17B were prepared in the same manner as in Example 1, IA, and IB, respectively, provided that 15g of 2-(l-methoxypropyl) acetate (boiling point 145°C) included in the polymerizable composition in Example 1 was changed to a mixed solution of 4g of 3-ethoxyethyl propionate (boiling point 166°C), 12g of ethyl lactate (boiling point 154°Q and 4g of 2-(l-methoxypropyl) acetate (boiling point 145°C), and were evaluated. The viscosity of the polymerizable composition at a temperature of 20°C is 9.5cP. (Example 18)
An optical compensatory element according to Example 18, a liquid crystal display according to Example 18 A, and a liquid crystal projector according to Example 18B were prepared in the same manner as in Example 1, IA, and IB, respectively, provided that 15g of 2-(l-methoxypropyl) acetate (boiling point 145°C) included in the polymerizable composition in Example 1 was changed to a mixed solution of 12g of 3-methoxymethyl propionate (boiling point 142°C), 4g of ethyl lactate (boiling point 1540Q and 4g of 2-(l-methoxypropyl) acetate (boiling point 145°C), and were evaluated. The viscosity of the polymerizable composition at a temperature of 20°C is 8.4cP. (Example 19)
An optical compensatory element according to Example 19, a liquid crystal display according to Example 19 A, and a liquid crystal projector according to Example 19B were prepared in the same manner as in Example 1, IA, and IB, respectively, provided that 15g of 2-(l-methoxypropyl) acetate (boiling point 145°C) included in the polymerizable composition in Example 1 was changed to a mixed solution of 12g of 3-methoxymethyl propionate (boiling point 1420C), 4g of butyl lactate (boiling point 186°C) and 4g of 2-(l-methoxypropyl) acetate (boiling point 145°C), and were evaluated. The viscosity of the polymerizable composition at a temperature of 200C is 8.5cP. (Example 20)
An optical compensatory element according to Example 20, a liquid crystal display according to Example 20 A, and a liquid crystal projector according to Example 20B were prepared in the same manner as in Example 1, IA, and IB, respectively, provided that 15g of 2-(l-methoxypropyl) acetate (boiling point 145°C) included in the polymerizable composition in Example 1 was changed to a mixed solution of 12g of 3-ethoxyethyl propionate (boiling point 166°C),4g of butyl lactate (boiling point 1860Q and 4g of 2-(l-methoxypropyl) acetate (boiling point 1450C), and were evaluated. The viscosity of the polymerizable composition at a temperature of 200C is 8.6cP. (Example 21)
An optical compensatory element according to Example 21, a liquid crystal 5 display according to Example 21 A, and a liquid crystal projector according to Example 21B were prepared in the same manner as in Example 1, IA, and IB, respectively, provided that 15g of 2-(l-methoxypropyl) acetate (boiling point 145°C) included in the polymerizable composition in Example 1 was changed to a mixed solution of 12g of 3-ethoxyethyl propionate (boiling point 166°C) and 8g of methyl ethyl o ketone (boiling point 80°C), and were evaluated. The viscosity of the polymerizable composition at a temperature of 200C is 5cP. (Comparative Example 1)
An optical compensatory element according to Comparative Example 1, a liquid crystal display according to Comparative Example IA, and a liquid crystal 5 projector according to Comparative Example IB were prepared in the same manner as in Example 1, IA, and IB, respectively, provided that 15g of 2-(l-methoxypropyl) acetate (boiling point 145°C) included in the polymerizable composition in Example 1 was changed to 15g of methyl ethyl ketone (boiling point 800C), and were evaluated. The viscosity of the polymerizable composition at a temperature of 2O0C is 5cP. o (Comparative Example 2)
An optical compensatory element according to Comparative Example 2, a liquid crystal display according to Comparative Example 2A, and a liquid crystal projector according to Comparative Example 2B were prepared in the same manner as in Example 1, IA, and IB, respectively, provided that 15g of 2-(l-methoxypropyl) 5 acetate (boiling point 145°C) included in the polymerizable composition in Example 1 was changed to 2Og of methyl ethyl ketone (boiling point 800C), and were evaluated. The viscosity of the polymerizable composition at a temperature of 200C is 5cP. (Comparative Example 3)
An optical compensatory element according to Comparative Example 3, a liquid crystal display according to Comparative Example 3 A, and a liquid crystal projector according to Comparative Example 3B were prepared in the same manner as in Example 1, IA, and IB, respectively, provided that 15g of 2-(l-methoxypropyl) acetate (boiling point 145°C) included in the polymerizable composition in Example 1 was changed to 15g of cyclohexanon (boiling point 155°C), and were evaluated. (Comparative Example 4)
An optical compensatory element according to Comparative Example 4, a liquid crystal display according to Comparative Example 4A, and a liquid crystal projector according to Comparative Example 4B were prepared in the same manner as in Example 1, IA, and IB, respectively, provided that 15g of 2-(l-methoxypropyl) acetate (boiling point 145°C) included in the polymerizable composition in Example 1 was changed to 15gof N-methylpyrrolidone (boiling point 81°C-82°C/10mmHg), and were evaluated.
Table 1
Figure imgf000087_0001
Table 1 shows that the optically anisotropic layers according to Examples 1 through 21 each exhibit a more favorable result of haze (%) without any occurrences of surface anomaly as compared with the optically anisotropic layers according to Comparative Examples 1 to 4. Table 2
Figure imgf000088_0001
Table 2 shows that the liquid crystal displays according to Examples IA through 21 A each excel in viewing angle dependency and have a wide viewing angle as compared with the liquid crystal displays according to Comparative Examples IA to 4A, and the liquid crystal projectors according to Examples IB through 21B respectively have a high contrast as compared with the liquid crystal projectors according to Comparative Examples IB to 4B.
A polymerizable composition according to the present invention, an optically anisotropic layer comprising the polymerizable composition, an optical compensatory element including the optically anisotropic layer, and a liquid crystal display comprising the optical compensatory element can be suitably used typically in mobile phones, monitors for personal computers, television sets, and liquid crystal projectors.

Claims

CXAIMS
1. A polymerizable composition comprising: a polymerizable liquid crystal compound, and a solvent, wherein the solvent comprises any one of compounds selected from (A) an alkyl acetyl compound having a boiling point of 100°C or more, (B) a hydroxy carboxylic acid alkyl ester compound, and (C) an alkoxy-substituted alkyl carboxylic acid alkyl ester compound.
2. The polymerizable composition according to claim 1, wherein the solvent comprises two compounds selected from (A) the alkyl acetyl compound having a boiling point of 1000C or more, (B) the hydroxy carboxylic acid alkyl ester compound, and (C) the alkoxy-substituted alkyl carboxylic acid alkyl ester compound.
3. The polymerizable composition according to any one of claims 1 to 2, wherein (A) the alkyl acetyl compound having a boiling point of 100°C or more is an alkoxy alkyl acetate compound.
4. The polymerizable composition according to claim 3, wherein the alkoxy alkyl acetate compound comprises any one of 2-(l-methoxy propyl) acetate and propylene glycol monoalkyl ether acetate.
5. The polymerizable composition according to any one of claims 3 to 4, wherein the alkoxy alkyl acetate compound is propylene glycol monoalkyl ether acetate.
6. The polymerizable composition according to any one of claims 1 to 5, wherein (B) the hydroxy carboxylic acid alkyl ester compound is at least one selected from 3-hydroxyethyl butanoic acid, 3-hydroxymethyl butanoic acid, ethyl lactate, and butyl lactate.
7. The polymerizable composition according to any one of claims 1 to 6, wherein (C) the alkoxy-substituted alkyl carboxylic acid alkyl ester compound is at least one selected from 2-ethoxyethyl propionate, 3-ethoxy ethyl propionate, 2-methoxymethyl propionate, 3-methoxyethyl propionate, and 3-methoxymethyl
5 propionate.
8. The polymerizable composition according to any one of claims 1 to 7, wherein the solvent further comprises an alkyl ketone compound.
9. The polymerizable composition according to claim 8, wherein the alkyl ketone compound is at least any one of acetone and methyl ethyl ketone. 0
10. The polymerizable composition according to any one of claims 1 to 9, wherein the content of the solvent is 200 parts by mass to 1,000 parts by mass relative to 100 parts by mass of the polymerizable liquid crystal compound.
11. The polymerizable composition according to any one of claims 1 to 10, wherein the polymerizable composition has a viscosity of 2cP to 3OcP at a 5 temperature of 20°C.
12. The polymerizable composition according to any one of claims 1 to 11, wherein the polymerizable liquid crystal compound comprises a discotic liquid crystal compound.
13. The polymerizable composition according to any one of claims 1 to 11, o wherein the polymerizable liquid crystal compound comprises a rod-shaped liquid crystal compound.
14. An optically anisotropic layer comprising: a polymerizable composition, wherein the polymerizable composition comprises a polymerizable liquid 5 crystal compound and a solvent which comprises any one of compounds selected from (A) an alkyl acetyl compound having a boiling point of 100°C or more, (B) a hydroxy carboxylic acid alkyl ester compound, and (C) an alkoxy-substituted alkyl carboxylic acid alkyl ester compound.
15. The optically anisotropic layer according to claim 14, wherein the angle of alignment of the liquid crystal compound in the polymerizable liquid crystal compound is fixed in a state of being oblique to a thickness direction of the optically anisotropic layer.
16. The optically anisotropic layer according to any one of claims 14 to 15, wherein the angle of alignment of the liquid crystal compound in the polymerizable liquid crystal compound is fixed in a hybrid alignment in which the angle of alignment varies in a thickness direction of the optically anisotropic layer.
17. The optically anisotropic layer according to any one of claims 14 to 16, wherein the direction of alignment of the liquid crystal compound included in the polymerizable liquid crystal compound is fixed in a certain direction of alignment.
18. A method for manufacturing an optically anisotropic layer comprising: applying to at least one surface of a support a polymerizable composition according to any one of claims 1 to 13, and heating the polymerizable composition up to 130°C or more to remove the solvent.
19. An optical compensatory element comprising: a support, and an optically anisotropic layer, wherein the optically anisotropic layer is arranged on at least one surface of tl e support, and the optically anisotropic layer is an optically anisotropic layer according to any one of claims 14 to 17.
20. The optical compensatory element according to claim 19, wherein the optical compensatory element comprises two optically anisotropic layers arranged so as to each have a different direction of alignment.
21. The optical compensatory element according to any one of claims 19 to 20, wherein the two layers each having a different direction of alignment are arranged on one surface of the support.
22. The optical compensatory element according to any one of claims 19 to
21, wherein the two layers each having the different direction of alignment are arranged so as to sandwich the support.
23. The optical compensatory element according to any one of claims 19 to
22, wherein the optical compensatory element comprises two layers arranged so as to have a different direction of alignment perpendicular to each other.
24. A liquid crystal display comprising: a liquid crystal device, an optical compensatory element, and a polarizing element, wherein the liquid crystal device comprises one pair of electrodes and liquid crystal molecules encapsulated in between the at least one pair of electrodes, wherein the optical compensatory element is arranged on or above any one of the light incident surface and the light output surface of the liquid crystal device or both of the surfaces, and the optical compensatory element is an optical compensatory element according to any one of claims 19 to 23, and wherein the polarizing element is arranged so as to face the liquid crystal device and the optical compensatory element.
25. The liquid crystal display according to claim 24, wherein the liquid crystal device is a twisted nematic liquid crystal device.
26. A liquid crystal projector comprising: a light source, a projection optical system, and a liquid crystal display, wherein the projection optical system forms an image on a screen from light optically modulated by the liquid crystal display, and wherein the liquid crystal display is irradiated by light illuminated from the light source and is a liquid crystal display according to any one of claims 24 to 25.
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