WO2018062424A1 - Optical element, method for producing optical element, and liquid crystal display device - Google Patents

Optical element, method for producing optical element, and liquid crystal display device Download PDF

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Publication number
WO2018062424A1
WO2018062424A1 PCT/JP2017/035324 JP2017035324W WO2018062424A1 WO 2018062424 A1 WO2018062424 A1 WO 2018062424A1 JP 2017035324 W JP2017035324 W JP 2017035324W WO 2018062424 A1 WO2018062424 A1 WO 2018062424A1
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Prior art keywords
liquid crystal
layer
optical element
light
reflective polarizer
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PCT/JP2017/035324
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French (fr)
Japanese (ja)
Inventor
匡広 渥美
齊藤　之人
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富士フイルム株式会社
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Priority to JP2018542880A priority Critical patent/JP6687745B2/en
Priority to KR1020197008768A priority patent/KR102140552B1/en
Publication of WO2018062424A1 publication Critical patent/WO2018062424A1/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
    • 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
    • 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

Definitions

  • the present invention relates to an optical element, a method for manufacturing the optical element, and a liquid crystal display device.
  • LCDs liquid crystal display devices
  • the liquid crystal display device has a configuration in which a backlight (hereinafter also referred to as BL), a backlight side polarizing plate, a liquid crystal cell, a viewing side polarizing plate, and the like are provided in this order.
  • BL backlight
  • a backlight side polarizing plate a backlight side polarizing plate
  • LCD performance improvement development for power saving, high definition, and color reproducibility is progressing as LCD performance improvement. These performance improvements are particularly noticeable in small-sized liquid crystal display devices such as tablet PCs and smartphones.
  • the reflective polarizer is an optical element that transmits only light oscillating in a specific polarization direction among light incident while oscillating in all directions, and reflects light oscillating in other polarization directions. This makes it possible to recycle the light that is reflected without being reflected by the reflective polarizer, thereby improving the light utilization efficiency in the LCD.
  • a structure in which layers formed by fixing a cholesteric liquid crystal phase are laminated is employed. Since the cholesteric liquid crystal phase exhibits circularly polarized light reflectivity at a wavelength corresponding to the helical pitch, it is possible to widen the reflection wavelength region by laminating a plurality of layers having different pitches.
  • Japanese Patent Application Laid-Open No. 1-133003 discloses a reflective polarizing plate having a structure in which a ⁇ / 4 plate and a layer in which a cholesteric liquid crystal phase is fixed are laminated, and three or more cholesteric liquid crystal phases having different cholesteric liquid crystal phase pitches. A technique for improving the light utilization factor of BL by broadening the reflection wavelength region by using a fixed layer is described.
  • Japanese Laid-Open Patent Publication No. 2009-15200 proposes a method of forming an optical functional film by generating wrinkles on the surface and applying an optically anisotropic material such as a liquid crystal compound on the surface thereof.
  • a liquid crystal display device using a polarizing plate in which a layer formed by fixing a cholesteric liquid crystal phase and a ⁇ / 4 plate contributes to the improvement of light utilization efficiency of BL light. From the viewpoint of power saving, high definition, and color reproducibility improvement, an oblique color change is required to be improved at a higher level. Thus, it is desired to develop a new member capable of improving the oblique color change in the liquid crystal display device.
  • the present invention has been made in view of the above circumstances, and includes an optical element capable of improving oblique color change when incorporated in a liquid crystal display device, a method for manufacturing the optical element, and the optical element.
  • An object is to provide a liquid crystal display device.
  • the oblique color change is caused by the fact that the transmitted light in the oblique direction becomes elliptically polarized light due to the phase difference due to the cholesteric alignment of the liquid crystal, and all the light transmitted through the ⁇ / 4 plate cannot be converted into linearly polarized light. to cause. Since the refractive index ellipsoid of the liquid crystal phase with the fixed orientation is usually arranged spontaneously in the orientation regulating direction of the substrate, it is inherent to the liquid crystal material.
  • the optical element of the present invention includes a reflective polarizer in which a cholesteric liquid crystal phase composed of a rod-like liquid crystal compound is fixed,
  • the reflective polarizer has a front retardation value Re of 0 nm ⁇ Re ⁇ 10 nm at a reflection center wavelength of +80 nm, and an absolute value
  • “front” means a direction (normal direction) perpendicular to the surface of the reflective polarizer.
  • the polar angle of 50 ° means a direction inclined by 50 ° with respect to an axis (normal line) orthogonal to the plane of the reflective polarizer.
  • the retardation value Ret having a polar angle of 50 ° may be described as an oblique Ret (50 °) for the sake of simplicity.
  • the reflective polarizer comprises a first light reflecting layer, a second light reflecting layer, and a third light reflecting layer, Any one of the first light reflection layer, the second light reflection layer, and the third light reflection layer is a blue reflection layer having a reflectance peak having a reflection center wavelength of 380 to 499 nm and a half width of 100 nm or less. Any one is a green reflective layer having a reflectance peak having a reflection center wavelength of 500 to 599 nm and a half-value width of 200 nm or less, and any one is a reflectance having a reflection center wavelength of 600 to 750 nm and a half-value width of 150 nm or less A red reflective layer having a peak of
  • the optical element of the present invention preferably includes a ⁇ / 4 plate on at least one surface of the reflective polarizer.
  • the method for producing an optical element of the present invention is a method for producing an optical element comprising a reflective polarizer in which a cholesteric liquid crystal phase composed of a rod-like liquid crystal compound is fixed, Forming a coating film from a polymerizable composition containing a rod-like liquid crystal compound on a support having a polymer main chain oriented in the film in-plane direction;
  • the reflective polarizer is formed by a step of curing the coating film and a step of biaxially shrinking the cured coating film together with the support.
  • the biaxial contraction process is performed so that the contraction magnification of each of the four sides of the support is 15% or more and 25% or less.
  • the liquid crystal display device of the present invention includes at least the optical element of the present invention, a liquid crystal cell, and a backlight unit.
  • the optical element of the present invention includes a reflective polarizer in which a cholesteric liquid crystal phase composed of a rod-like liquid crystal compound is fixed.
  • the reflective polarizer has a reflection center wavelength of +80 nm
  • the front retardation value Re is 0 nm ⁇ Re ⁇ 10 nm.
  • of the retardation value Ret in the polar angle 50 ° direction is
  • the front retardation value Re is 0 nm ⁇ Re ⁇ 10 nm at the reflection center wavelength of +80 nm, and the absolute value of the retardation value Ret in the polar angle 50 ° direction
  • ⁇ 50 nm can be obtained.
  • the front retardation value Re is 0 nm ⁇ Re ⁇ 10 nm at the reflection center wavelength of +80 nm
  • has an optical element with a reflective polarizer satisfying
  • a numerical range expressed using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.
  • the “half width” of a peak means the width of the peak at a peak height of 1/2.
  • the reflection center wavelength and the half-value width of the reflective polarizer can be measured with an integral reflectometer.
  • measurement is performed using a spectrophotometer V-550 connected to an integrating sphere device ILV-471 (both manufactured by JASCO Corporation) as an integrating reflectometer.
  • the wavelength value on the short wave side is ⁇ 1 (nm)
  • the wavelength value on the long wave side is ⁇ 2 (nm).
  • Re ( ⁇ ) and Rth ( ⁇ ) each represent in-plane retardation and thickness direction retardation at wavelength ⁇ .
  • the retardations Re ( ⁇ ) and Rth ( ⁇ ) are obtained by using AxoScan (manufactured by Axometric).
  • the in-plane retardation Re ( ⁇ ) is a value measured by making light having a wavelength ⁇ incident from the normal direction of the film surface.
  • Thickness direction retardation Rth ( ⁇ ) ((Nx + Ny) / 2 ⁇ Nz) ⁇ d Is calculated.
  • the oblique retardation Ret (50 °) is a value measured by making light having a wavelength ⁇ from a polar angle of 50 ° incident on the film surface.
  • the oblique retardation value Ret (50 °) is a measured value of retardation when the polar angle is 50 °, that is, the angle ⁇ inclined from the normal direction of the film surface is 50 °.
  • the sign of the oblique retardation value Ret (50 °) is the sign of the retardation when the slow axis is regarded as a direction parallel to the film surface.
  • the sign of the oblique retardation value Ret (50 °) is positive, and the slow axis is perpendicular to the film surface.
  • the sign of the oblique retardation value Ret (50 °) is negative.
  • visible light means 380 nm to 780 nm.
  • the angle for example, an angle such as “90 °” and the relationship thereof (for example, “orthogonal”, “parallel”, “intersection at 45 °”, etc.)
  • the range of allowable error is included. For example, it means that the angle is within the range of strict angle ⁇ 10 °, and the error from the strict angle is preferably 5 ° or less, and more preferably 3 ° or less.
  • the “absorption axis” of a polarizer or a polarizing plate means a direction having the highest absorbance.
  • the “transmission axis” means a direction that forms an angle of 90 ° with the “absorption axis”.
  • the “slow axis” of a retardation film or the like means a direction in which the refractive index is maximized.
  • “polarizer” and “reflection polarizer” are used separately.
  • numerical values, numerical ranges, and qualitative expressions for example, “equivalent”, “equal”, etc.) indicating optical characteristics of each member such as a retardation region, a retardation film, and a liquid crystal layer are used. ) Shall be interpreted to indicate numerical values, numerical ranges and properties including generally allowable errors for liquid crystal display devices and members used therefor.
  • FIG. 1 is a schematic cross-sectional view showing an embodiment of the optical element of the present invention.
  • the optical element of the present invention is not limited to this embodiment.
  • an optical element 10 includes a reflective polarizer 13 laminated on a ⁇ / 4 plate 12 with an adhesive layer 20 interposed therebetween.
  • the reflective polarizer 13 is obtained by fixing a cholesteric liquid crystal phase composed of a rod-like liquid crystal compound.
  • the front retardation value Re is 0 nm ⁇ Re ⁇ 10 nm at the reflection center wavelength of +80 nm, and the polar angle is in the direction of 50 °.
  • of the retardation value Ret is
  • the reflective polarizer 13 of the present invention is constituted by a biaxially contracted film obtained by biaxially contracting an optical film in which a cholesteric liquid crystal phase is fixed.
  • the optical element of the present invention has a reflective polarizer, and the light reflective layer formed by fixing the cholesteric liquid crystal phase contained in the reflective polarizer has at least one of right circularly polarized light and left circularly polarized light in the vicinity of its reflection center wavelength. It can be reflected in the wavelength band.
  • the front retardation value Re is preferably 0 nm ⁇ Re ⁇ 5 nm, and the absolute value
  • the optical element of the present invention has a front retardation value and an oblique retardation value in the above ranges, there is no phase difference in obliquely incident light. Therefore, when incorporated in a liquid crystal display device, the oblique color change Can be suppressed.
  • FIG. 2 is a diagram showing a refractive index ellipsoid before and after biaxial contraction of a reflective polarizer (a layer in which a cholesteric liquid crystal phase made of a rod-like liquid crystal compound is fixed) in the optical element of the present invention.
  • FIG. 2a shows the refractive index ellipsoid before birefringing the reflective polarizer.
  • FIG. 2b shows the refractive index ellipsoid after biaxial contraction of the reflective polarizer.
  • FIG. 3 is a schematic cross-sectional view of another embodiment of the optical element of the present invention.
  • the reflective polarizer 13 in the optical element 11 of the present embodiment includes a first light reflecting layer 14a, a second light reflecting layer 14b, and a third light reflecting layer 14c. Then, the reflective polarizer 13 composed of the first light reflecting layer 14a, the second light reflecting layer 14b, and the third light reflecting layer 14c is formed on the ⁇ / 4 plate 12 via the adhesive layer 20. It is the aspect which is laminated
  • the reflective polarizer 13 including the three layers of the first light reflecting layer 14a, the second light reflecting layer 14b, and the third light reflecting layer 14c is not limited to the mode shown in FIG.
  • the ⁇ / 4 plate 12 may be in direct contact.
  • the reflective polarizer 13 may have a layer other than the first light reflecting layer 14a, the second light reflecting layer 14b, and the third light reflecting layer 14c.
  • the ⁇ / 4 plate 12 shown in FIGS. 1 and 3 may be a single layer or a laminate of two or more layers, and is preferably a laminate of two or more layers.
  • any one of the first light reflection layer, the second light reflection layer, and the third light reflection layer included in the reflective polarizer is a blue light reflection layer.
  • One is a green light reflecting layer, and any one is a red light reflecting layer, so that the reflective polarizer can reflect at least one of right circularly polarized light and left circularly polarized light for each of blue light, green light and red light.
  • the polarization state can be converted from circularly polarized light to linearly polarized light by the action of the ⁇ / 4 plate 12.
  • the circularly polarized light in the first polarization state (for example, right circularly polarized light) is substantially reflected by the reflective polarizer, while the circularly polarized light in the second polarization state (for example, left circularly polarized light) is substantially reflected.
  • the light in the second polarization state (for example, left circularly polarized light) that substantially passes through the reflective polarizer and passes through the reflective polarizer is converted into linearly polarized light by the ⁇ / 4 plate 12.
  • the light in the first polarization state substantially reflected by the reflective polarizer is recirculated by a reflective member (also referred to as a light guide or an optical resonator) described later, and the first polarization state is recirculated by the reflective polarizer.
  • a part of the light is reflected as circularly polarized light in one polarization state and the other part is transmitted as circularly polarized light in the second polarization state, thereby increasing the light utilization rate on the backlight side and improving the brightness of the liquid crystal display device.
  • the light emitted from the reflective polarizer that is, the polarization state of the transmitted light and the reflected light of the reflective polarizer can be measured, for example, by measuring the polarization with an Axoscan from Axometrics.
  • any one of the first light reflection layer 14a, the second light reflection layer 14b, and the third light reflection layer 14c has a reflectance peak with a reflection center wavelength of 380 to 499 nm and a half-value width of 100 nm or less.
  • a reflective layer any one of which is a green reflective layer having a reflectance peak with a reflection center wavelength of 500 to 599 nm and a half width of 200 nm or less, and any one of which has a reflection center wavelength of 600 to 750 nm and a half width of 150 nm or less.
  • a red reflective layer having a certain reflectance peak is preferred.
  • an infrared light reflection layer having a reflectance peak having a reflection center wavelength of 750 nm to 850 nm and a half width of 200 nm or less may be provided in contact with the third light reflection layer 14c.
  • the film thickness of the optical element of the present invention is preferably 3 to 120 ⁇ m, more preferably 5 to 100 ⁇ m, and particularly preferably 6 to 90 ⁇ m.
  • the blue reflective layer has a reflection peak having a reflection center wavelength in a wavelength band of 380 to 499 nm and a half width of 100 nm or less.
  • the reflection center wavelength of the blue reflective layer is preferably in the wavelength band of 430 to 480 nm, and more preferably in the wavelength band of 430 to 470 nm.
  • the full width at half maximum of the reflectivity peak of the blue reflective layer is preferably 100 nm or less, more preferably the full width at half maximum of this reflectivity peak is 90 nm or less, and the full width at half maximum of this reflectivity peak is 80 nm or less. It is particularly preferred.
  • the blue reflective layer preferably does not have a reflectance peak in the wavelength band of 500 to 750 nm.
  • the blue reflective layer preferably has an average reflectance of 500 to 750 nm of 5% or less.
  • the blue reflective layer preferably has a thickness of 2 to 10 ⁇ m, more preferably 3 to 7 ⁇ m.
  • the green reflective layer has a reflection peak having a reflection center wavelength in a wavelength band of 500 to 599 nm and a half width of 200 nm or less.
  • the reflection center wavelength of the green reflective layer is preferably in the wavelength band of 520 to 590 nm, and more preferably in the wavelength band of 520 to 580 nm.
  • the half width of the reflectance peak of the green reflective layer is preferably 160 nm or less, the half width of the reflectance peak is more preferably 125 nm or less, and the half width of the reflectance peak is 100 nm or less. It is more preferable that the half width of the reflectance peak is 95 nm or less.
  • the green reflective layer preferably has no reflectance peak in the wavelength bands of 380 to 499 nm and 600 to 750 nm.
  • the green reflective layer preferably has an average reflectance of 380 to 499 nm and 600 to 750 nm of 5% or less.
  • the green reflective layer preferably has a thickness of 2 to 10 ⁇ m, more preferably 3 to 7 ⁇ m.
  • the red reflective layer has a reflection peak having a reflection center wavelength in a wavelength band of 600 to 750 nm and a half width of 150 nm or less.
  • the reflection center wavelength of the red reflective layer is preferably in the wavelength band of 610 to 690 nm, and more preferably in the wavelength band of 610 to 660 nm.
  • the half width of the reflectance peak of the red reflective layer is more preferably 130 nm or less, the half width of the reflectance peak is particularly preferably 110 nm or less, and the half width of the reflectance peak is 100 nm or less. It is particularly preferred that
  • the red reflective layer preferably has no reflectance peak in the wavelength bands of 380 to 499 nm and 500 to 599 nm.
  • the red reflective layer preferably has an average reflectance of 380 to 499 nm and 500 to 599 nm of 5% or less.
  • the red reflective layer preferably has a thickness of 2 to 10 ⁇ m, more preferably 3 to 7 ⁇ m. All of the blue reflective layer, the green reflective layer, and the red reflective layer preferably have a half-value width of a reflectance peak of 30 nm or more in order to reflect light emitted from the backlight unit.
  • each of the blue, green, and red reflective polarizers By configuring as described above, it is possible to expand the reflection band of each of the blue, green, and red reflective polarizers.
  • a pitch gradient method capable of realizing a wide half-value width by gradually changing the helical pitch of the cholesteric liquid crystal phase can be used.
  • the pitch gradient method can be realized by the method described in 1995 (Nature 378, 467-469 1995), Japanese Patent Application Laid-Open No. 6-281814, or Japanese Patent No. 4990426.
  • Each of the three light reflecting layers is a reflective polarizer formed by fixing a cholesteric liquid crystal phase.
  • the wavelength giving the peak of reflectance (that is, the reflection center wavelength) can be adjusted by changing the pitch or refractive index of the helical structure in the cholesteric liquid crystal phase of the reflective polarizer formed by fixing the cholesteric liquid crystal phase. Changing the pitch can be easily adjusted by changing the amount of chiral agent added. Specifically, Fujifilm research report No. 50 (2005) p. There is a detailed description in 60-63.
  • the spiral direction of the helical structure of each cholesteric liquid crystal phase is not particularly limited, but the first light reflection layer, It is preferable that the spiral directions of the spiral structures of the cholesteric liquid crystal phases of the second light reflection layer and the third light reflection layer coincide. Thereby, it is possible to align the phase states of the circularly polarized light reflected by the respective layers and prevent different polarization states in the respective wavelength ranges, thereby increasing the light use efficiency.
  • each cholesteric liquid crystal phase has a right spiral structure, and the first light reflection layer and the second light reflection layer It is preferable that all of the third light reflection layers reflect right circularly polarized light at the reflection center wavelength.
  • each cholesteric liquid crystal phase has a left spiral structure, and the first light reflection layer and the second light reflection layer. It is also preferable that all of the third light reflecting layers reflect the left circularly polarized light at the reflection center wavelength.
  • the reflective polarizer in the optical element of the present invention is formed by curing and shrinking a polymerizable composition containing a rod-like liquid crystal compound.
  • the rod-shaped liquid crystal compound, the other components and the solvent, which are components of the polymerizable composition used for the production of the optical element will be described.
  • a rod-like liquid crystal compound which is a reflective polarizer material formed by fixing a cholesteric liquid crystal phase
  • the rod-like liquid crystal compound for example, those described in JP-A-11-513019 and JP-A-2007-279688 can be preferably used, but are not limited thereto.
  • the polymerizable composition used for forming the reflective polarizer formed by fixing the cholesteric liquid crystal phase is a rod-like liquid crystal compound, as well as other components such as a chiral agent, an alignment controller, a polymerization initiator, and an alignment aid. May be contained. Any known material can be used.
  • organic solvent As a solvent of the composition for forming each reflective polarizer, an organic solvent is preferably used.
  • organic solvents include amides (eg N, N-dimethylformamide), sulfoxides (eg dimethyl sulfoxide), heterocyclic compounds (eg pyridine), hydrocarbons (eg benzene, hexane), alkyl halides (eg , Chloroform, dichloromethane), esters (eg, methyl acetate, butyl acetate), ketones (eg, acetone, methyl ethyl ketone, cyclohexanone), ethers (eg, tetrahydrofuran, 1,2-dimethoxyethane). Alkyl halides and ketones are preferred. Two or more organic solvents may be used in combination.
  • the optical element of the present invention may include a support.
  • the support has a function of maintaining the layer shape of the cholesteric liquid crystal phase, and a reflective polarizer is formed on the support.
  • a ⁇ / 4 plate 12 included in the optical element of the present invention itself is used as a support, and a reflective polarizer is bonded to the ⁇ / 4 plate 12 as shown in FIG. Also good.
  • the entire ⁇ / 4 plate 12 formed on the support may be used as a support, and a reflective polarizer may be bonded to the support.
  • a transparent support is preferable, a polyacrylic resin film such as polymethyl methacrylate, a cellulose resin film such as cellulose triacetate, and a cycloolefin polymer film [for example, trade name “ARTON”, JSR And the trade name “ZEONOR”, manufactured by Nippon Zeon Co., Ltd.].
  • a polyacrylic resin film such as polymethyl methacrylate
  • a cellulose resin film such as cellulose triacetate
  • a cycloolefin polymer film for example, trade name “ARTON”, JSR And the trade name “ZEONOR”, manufactured by Nippon Zeon Co., Ltd.
  • the optical element of the present invention may not include a support for forming the reflective polarizer, but as a support for forming the reflective polarizer (hereinafter referred to as a temporary support). It is possible to use the optical polarizer of the present invention by forming the reflective polarizer and then peeling the reflective polarizer from the temporary support.
  • the optical element of the present invention includes a first light reflection layer, a second light reflection layer, and a third light reflection layer having different reflection center wavelengths, and each light reflection layer is formed using a temporary support. It is preferable to form an optical element of the present invention by laminating a reflective polarizer formed by laminating a light reflecting layer formed and peeled off from a temporary support to the ⁇ / 4 plate 12.
  • the temporary support is used in which the polymer main chain is oriented in the in-plane direction of the film, that is, in the plane orientation.
  • the index of the plane orientation uses the cross-sectional orientation degree P2z of the film.
  • the cross-sectional orientation degree P2z is preferably 0.1 or more and 0.3 or less, and more preferably 0.12 or more and 0.25 or less.
  • the method of setting the cross-sectional orientation degree P2z to 0.07 or more and 1 or less is not limited as long as the polymer main chain can be oriented in the in-plane direction, and biaxial stretching or biaxial extrusion, rolling, or solution casting is used. It is preferable to perform biaxial stretching.
  • the main chain can be oriented in the in-plane direction because only the thickness direction shrinks by fixing the area when the web is dried.
  • the cross-sectional orientation degree P2z of the film is defined by the following formula (1) and formula (2) calculated from the X-ray diffraction measurement.
  • P ⁇ 3 cos 2 ⁇ -1> / 2
  • P2z (Pxz + Pyz) / 2
  • ⁇ cos2 ⁇ > ⁇ (0, ⁇ ) cos2 ⁇ I ( ⁇ ) sin ⁇ d ⁇ / ⁇ (0, ⁇ ) I ( ⁇ ) sin ⁇ d ⁇ It is.
  • Pxz is the degree of orientation defined by the above formula (1) obtained from the X-ray diffraction measurement in the direction perpendicular to the film forming direction and the out-of-plane direction
  • Pyz is the width direction and the out-of-plane direction of the film. The degree of orientation defined by the above formula (1) obtained from the X-ray diffraction measurement in the direction perpendicular to.
  • the X-ray diffraction measurement employs transmission two-dimensional X-ray measurement, uses RINT RAPID manufactured by Rigaku Corporation, uses a Cu tube as the X-ray source, generates X-rays at 40 kV-36 mA, The 0.8 mm ⁇ film sample is fixed using a transmission sample stage, and the exposure time is 600 seconds.
  • the produced film may be stretched longitudinally at a desired stretching ratio in a longitudinal uniaxial stretching machine and then stretched at a desired stretching ratio in a tenter stretching machine. Or you may extend
  • the biaxially stretched film may be made into a roll film by cutting off both ends before winding up and winding up at the winding up.
  • the longitudinal and lateral stretching ratios are basically the same, but when shrinking in the width direction in longitudinal uniaxial stretching, the transverse stretching ratio may be increased so that the substantial deformation ratio from the initial stage becomes equal. A substantial vertical / horizontal deformation rate of about 5% is acceptable.
  • the intake air temperature, film film surface temperature, and stretching speed during stretching can be appropriately adjusted depending on the desired stretching ratio.
  • the reflective polarizer is preferably provided with an alignment layer in order to obtain a desired cholesteric liquid crystal phase.
  • the alignment layer can be provided by means such as a rubbing treatment of an organic compound (preferably a polymer), oblique vapor deposition of an inorganic compound, or formation of a layer having a microgroove.
  • an alignment layer in which an alignment function is generated by application of an electric field, application of a magnetic field, or light irradiation is also known.
  • the alignment layer is preferably formed by rubbing the surface of the polymer film.
  • the support can function as an orientation layer by directly subjecting the support to an orientation treatment (for example, rubbing treatment) without providing an orientation layer.
  • an orientation treatment for example, rubbing treatment
  • An example of such a support is PET (polyethylene terephthalate).
  • the lower liquid crystal layer behaves as an alignment layer and the upper liquid crystal layer In some cases.
  • the upper liquid crystal can be aligned without providing an alignment layer or without performing a special alignment process (for example, rubbing process).
  • the surface of the alignment layer or the support is preferably subjected to a rubbing treatment. Moreover, it is also possible to carry out a rubbing treatment on the surfaces of the first, second, and third light reflecting layers as necessary.
  • the rubbing treatment can be generally performed by rubbing the surface of a film containing a polymer as a main component with paper or cloth in a certain direction. A general method of rubbing is described in, for example, “Liquid Crystal Handbook” (issued by Maruzen, October 30, 2000).
  • the optical element of the present invention may have a ⁇ / 4 plate on at least one surface of the reflective polarizer.
  • the ⁇ / 4 plate is a layer for converting circularly polarized light that has passed through the reflective polarizer into linearly polarized light.
  • Rth ( ⁇ ) retardation
  • Rth (550) of the ⁇ / 4 plate is preferably ⁇ 120 to 120 nm, more preferably ⁇ 80 to 80 nm, and particularly preferably ⁇ 70 to 70 nm.
  • the ⁇ / 4 plate may be an optically anisotropic support having a ⁇ / 4 function, or may have an optically anisotropic layer or the like on a support made of a polymer film. .
  • ⁇ Adhesive layer (adhesive layer)>
  • “adhesion” is used in a concept including “adhesion”.
  • the ⁇ / 4 plate and the reflective polarizer are laminated in direct contact or via an adhesive layer.
  • the reflective polarizers may be laminated not only in a form in which they are in direct contact with each other, but also between each reflective polarizer via an adhesive layer.
  • Examples of the pressure-sensitive adhesive used for the adhesive layer include resins such as polyester resins, epoxy resins, polyurethane resins, silicone resins, and acrylic resins. You may use these individually or in mixture of 2 or more types.
  • an acrylic resin is preferable because it is excellent in reliability such as water resistance, heat resistance, and light resistance, has good adhesion and transparency, and can easily adjust the refractive index to be compatible with a liquid crystal display. Quality etc. are included.
  • a sheet-like photo-curing adhesive (Toagosei Group Research Annual Report 11, TREND 2011, No. 14) can be used for the adhesive layer. Bonding between optical films is easy, like an adhesive, crosslinks and cures with ultraviolet rays (UV), improves storage elastic modulus, adhesive strength and heat resistance, and is an adhesive method suitable for the present invention. .
  • UV ultraviolet rays
  • the optical element of the present invention may have a polarizer in combination with the ⁇ / 4 plate.
  • the polarizer is an absorptive polarizer that transmits the first linearly polarized light and absorbs or reflects the second linearly polarized light orthogonal to the first linearly polarized light, and the slow axis of the ⁇ / 4 plate and
  • the angle formed with the absorption axis of the polarizer is preferably 30 to 60 °.
  • This polarizer is disposed opposite to the reflective polarizer with the ⁇ / 4 plate interposed therebetween.
  • the polarizer it is preferable to use a polymer film in which iodine is adsorbed and oriented.
  • the polymer film is not particularly limited, and various types can be used.
  • polyvinyl alcohol films polyethylene terephthalate films, ethylene / vinyl acetate copolymer films, partially saponified films of these, hydrophilic polymer films such as cellulose films, polyvinyl alcohol dehydrated products and polychlorinated Examples include polyene-based oriented films such as vinyl dehydrochlorinated products.
  • the thickness of the polarizer is not particularly limited, and is usually 5 to 80 ⁇ m, preferably 5 to 50 ⁇ m, more preferably 5 to 25 ⁇ m.
  • FIG. 4 is a method for producing an optical element including a reflective polarizer in which a cholesteric liquid crystal phase composed of a rod-like liquid crystal compound is fixed, and a step of forming a coating film from a polymerizable composition containing a rod-like liquid crystal compound (1 ), Curing the coating film to fix the cholesteric liquid crystal phase (2), biaxially contracting the cured coating film (3), and further curing the biaxially contracted coating film (4) ) To form a reflective polarizer.
  • the step (4) is preferably performed in order to improve wet heat durability, but the optical property is not changed by the step (4), and therefore it is not necessarily performed depending on the use environment.
  • a reflective polarizer having an isotropic refractive index ellipsoid can be obtained. Therefore, by incorporating this optical element into a liquid crystal display device, it is possible to satisfactorily convert circularly polarized light into linearly polarized light with the ⁇ / 4 plate without breaking circularly polarized light transmitted in an oblique direction. Thereby, the color change of the diagonal direction can be reduced and also favorable diagonal brightness
  • a coating composition containing a rod-like liquid crystal compound (hereinafter may be referred to as a polymerizable liquid crystal composition) is applied to the surface of a support or a substrate or the lower reflective polarizer.
  • a film is formed.
  • the polymerizable liquid crystal composition is preferably prepared as a coating solution in which a material is dissolved and / or dispersed in a solvent.
  • the coating liquid can be applied by various methods such as a wire bar coating method, an extrusion coating method, a direct gravure coating method, a reverse gravure coating method, and a die coating method.
  • a liquid crystal composition can be discharged from a nozzle using an ink jet apparatus to form a coating film.
  • the polymerizable liquid crystal composition applied to the surface to become a coating film is brought into a cholesteric liquid crystal phase.
  • the coating film may be dried and the solvent may be removed to obtain a cholesteric liquid crystal phase.
  • the liquid crystal phase transition temperature of the polymerizable liquid crystal composition is preferably in the range of 10 to 250 ° C., more preferably in the range of 10 to 150 ° C. from the viewpoint of production suitability and the like.
  • a cooling step or the like may be required to lower the temperature to a temperature range exhibiting a liquid crystal phase.
  • the heating temperature of a coating film shall be 200 degrees C or less from a viewpoint from the efficient utilization of a thermal energy, the heat resistance of a board
  • the temperature at this time is the film surface temperature, and can be measured with PT-2LD manufactured by OPTEX.
  • the direction of rotation of the cholesteric liquid crystal phase can be adjusted by the type of liquid crystal used or the type of chiral agent added, and the helical pitch (ie, selective reflection wavelength) can be adjusted by the concentration of these materials.
  • the wavelength of a specific region reflected by each reflective polarizer can be shifted depending on various factors of the manufacturing method.
  • the cholesteric liquid crystal phase is immobilized. It can be shifted depending on conditions such as temperature, illuminance, and irradiation time. Therefore, these conditions are determined according to the desired reflection wavelength.
  • the coating film in the cholesteric liquid crystal phase is irradiated with ultraviolet rays to advance the curing reaction.
  • a light source such as an ultraviolet lamp is used.
  • the curing reaction of the polymerizable liquid crystal composition proceeds by irradiating with ultraviolet rays, and the cholesteric liquid crystal phase is fixed.
  • the amount of irradiation energy of ultraviolet rays in general, preferably about 10mJ / cm 2 ⁇ 200mJ / cm 2, 20mJ / cm 2 ⁇ 100mJ / cm 2 approximately is more preferable.
  • ultraviolet irradiation may be performed under heating conditions. Moreover, it is preferable to maintain the temperature at the time of ultraviolet irradiation in the temperature range which exhibits a cholesteric liquid crystal phase so that a cholesteric liquid crystal phase may not be disturbed. Also, since the oxygen concentration in the atmosphere is related to the degree of polymerization, if the desired degree of polymerization is not reached in the air and the film strength is insufficient, the oxygen concentration in the atmosphere is reduced by a method such as nitrogen substitution. It is preferable. A preferable oxygen concentration is preferably 10% or less, more preferably 7% or less, and most preferably 3% or less.
  • the reaction rate of the curing reaction (for example, polymerization reaction) proceeded by ultraviolet irradiation is such that the cholesteric liquid crystal layer is prevented from wrinkling due to biaxial shrinkage in the next step (3), and the mechanical properties of the layer are reduced. From the standpoint of maintaining strength and suppressing unreacted substances from flowing out of the layer, it is preferably 25% to 70%, more preferably 30% to 60%.
  • the reaction rate can be measured by comparing the absorption intensity of the infrared vibration spectrum of a reactive group (for example, a polymerizable group) before and after the reaction proceeds. In order to improve the reaction rate, a method of increasing the irradiation amount of ultraviolet rays to be irradiated and polymerization under a nitrogen atmosphere or heating conditions are effective.
  • the cured layer obtained in (2) is biaxially contracted.
  • a known method can be used for the biaxial contraction.
  • the produced film having a coating film of a cholesteric liquid crystal phase is fixed by a tenter on four sides with a batch stretching machine, heated, and thermally contracted. It is preferable to contract at a contraction rate of 10% / min to 100% / min.
  • the shrinkage ratio is determined by the tenter's fixed position. By setting the tenter's fixed position according to the desired shrinkage ratio, the shrinkage ratio can be adjusted to be different even if the supply air temperature and film film surface temperature are the same. Is possible.
  • the vertical and horizontal shrinkage ratios are basically the same, but the substantial vertical and horizontal deformation ratios are allowed if they differ by about 5%.
  • the air supply temperature at the time of shrinkage, the film film surface temperature, and the shrinkage speed can be appropriately adjusted according to a desired shrinkage ratio.
  • the film surface temperature during shrinkage is preferably the glass transition point Tg-10 to Tg + 20 ° C., more preferably Tg-5 ° C. to Tg + 15 ° C. of the support on which the cholesteric liquid crystal phase is formed.
  • the layer contracted in (3) is further irradiated with ultraviolet rays to advance the curing reaction.
  • the polymerizable liquid crystal composition can be further cured to improve the wet heat durability of the immobilized cholesteric liquid crystal phase.
  • the optical characteristics do not change before and after the irradiation with ultraviolet rays.
  • 100 mJ / cm is preferably 2 ⁇ 1000mJ / cm 2 approximately, 200mJ / cm 2 ⁇ 500mJ / cm 2 approximately is more preferable.
  • the heating conditions and the atmospheric conditions are the same as in the step (2).
  • the reaction rate of the curing reaction (for example, polymerization reaction) proceeded by ultraviolet irradiation is 70% or more from the viewpoint of maintaining the mechanical strength of the layer and suppressing unreacted substances from flowing out of the layer. Preferably, it is 80% or more, more preferably 90% or more.
  • the state in which the liquid crystal phase is “fixed” is the most typical and preferred mode in which the orientation of the liquid crystal compound in the cholesteric liquid crystal phase is maintained.
  • the alignment state of the cholesteric liquid crystal phase is preferably fixed by a curing reaction that proceeds by ultraviolet irradiation.
  • this layer does not have fluidity at 0 ° C. to 50 ° C., and can maintain a fixed orientation form stably without causing a change in the orientation form due to an external field or an external force. It is preferable to be in a ready state.
  • the fixed orientation form can be kept stable in a temperature range of ⁇ 30 ° C. to 70 ° C. under more severe conditions.
  • the liquid crystal composition in each reflective polarizer no longer needs to exhibit liquid crystal properties.
  • the liquid crystal composition may have a high molecular weight due to a curing reaction and may no longer have liquid crystallinity.
  • substantially a vertical and horizontal deformation ratio of about 5% is allowable means that when the vertical contraction is 10%, the horizontal contraction is 15%. This means that it can be tolerated to the extent that when the vertical contraction is 15%, the horizontal contraction is 10%.
  • FIG. 5 is a schematic configuration diagram showing an embodiment of the liquid crystal display device of the present invention.
  • the liquid crystal display device 51 of this embodiment includes a backlight unit 31, an optical sheet member 21 including the optical element 11 of the present invention, a thin layer transistor substrate 41, a liquid crystal cell 42, a color filter substrate 43, And a display-side polarizing plate 44.
  • the optical sheet member 21 is formed by bonding the optical element 11 of the present invention to the backlight side polarizing plate 1 through the adhesive layer 20.
  • the backlight side polarizing plate 1 includes a polarizer 3 and a retardation film 2 provided with a polarizing plate protective film 4.
  • the backlight unit 31 has blue light having an emission center wavelength in the wavelength band of 430 to 480 nm, green light having an emission center wavelength in the wavelength band of 500 to 600 nm, and peaks of emission intensity in the wavelength band of 600 to 700 nm. It is preferable to provide a light source that emits at least a part of red light. Furthermore, it is preferable that the backlight unit 31 includes a reflecting member that converts and reflects the polarization state of the light output from the backlight unit 31 and reflected by the optical element 11.
  • the full width at half maximum of blue light and green light is 100 nm or less.
  • red light has an emission center wavelength in a wavelength band of 600 to 700 nm, and a half-value width of red light is 100 nm or less.
  • the cholesteric liquid crystal phase which is an RGB light reflection layer is improved while combining with an RGB (red, green and blue) narrow-band backlight while improving color reproducibility.
  • a sufficient brightness enhancement performance can be realized by the optical element 11 of the above-described embodiment having a simple configuration of a reflective polarizer and a ⁇ / 4 plate.
  • the liquid crystal display device it is preferable to dispose a layer that changes the polarization state of light between the third light reflection layer of the optical element and the backlight unit. This is because the layer that changes the polarization state of the light functions as a layer that changes the polarization state of the light reflected from the reflective polarizer, and the luminance can be improved.
  • the layer that changes the polarization state of light include a polymer layer having a refractive index higher than that of the air layer.
  • the polymer layer having a refractive index higher than that of the air layer examples include a hard coat (HC) treatment layer, an antiglare ( Various low reflection layers such as AG) treatment layer and low reflection (AR) treatment layer, triacetyl cellulose (TAC) film, acrylic resin film, cycloolefin polymer (COP) resin film, stretched PET film and the like.
  • HC hard coat
  • AR low reflection
  • TAC triacetyl cellulose
  • acrylic resin film acrylic resin film
  • COP cycloolefin polymer
  • stretched PET film stretched PET film and the like.
  • the layer that changes the polarization state of light may also serve as a support.
  • the relationship between the average refractive index of the layer that changes the polarization state of the light reflected from the reflective polarizer and the average refractive index of the third light reflecting layer is: Preferably, 0 ⁇
  • the layer that changes the polarization state of the light may be integrated with the optical element or may be provided separately from the optical element.
  • the driving mode of the liquid crystal cell 42 is not particularly limited, and is twisted nematic (TN), super twisted nematic (STN), vertical alignment (VA), in-plane switching (IPS), optically compensated bend cell (OCB). ) And other modes can be used.
  • the liquid crystal cell is preferably VA mode, OCB mode, IPS mode, or TN mode, but is not limited thereto.
  • the configuration shown in FIG. the configuration shown in FIG.
  • the specific configuration of the liquid crystal display device is not particularly limited, and a known configuration can be adopted.
  • the configuration of the backlight unit may be an edge light method using a light guide plate or a reflection plate as a constituent member, or a direct type.
  • the backlight unit includes a reflection member at the rear portion of the light source for converting and reflecting the polarization state of the light emitted from the light source and reflected by the optical element.
  • a reflection member at the rear portion of the light source for converting and reflecting the polarization state of the light emitted from the light source and reflected by the optical element.
  • the backlight unit preferably further includes a known diffusion plate, diffusion sheet, prism sheet (for example, 3M brightness enhancement film “BEF”), and a light guide.
  • a known diffusion plate for example, 3M brightness enhancement film “BEF”
  • BEF 3M brightness enhancement film
  • Other members are also described in Japanese Patent No. 3416302, Japanese Patent No. 3363565, Japanese Patent No. 4091978, Japanese Patent No. 3448626, and the contents of these publications are incorporated in the present invention.
  • FIG. 6 shows a schematic configuration of the liquid crystal display device of the present embodiment.
  • the liquid crystal display device 60 of the present embodiment has a configuration in which the optical element 11 is further provided on the display surface (most visible side) of the liquid crystal display device 51 described above.
  • the liquid crystal display device 51 is not limited to the liquid crystal display device 51 below the optical element 11, and other types of liquid crystal display devices may be provided.
  • the optical element 11 is arranged so that ⁇ / 4 is on the display side polarizing plate 44 (see FIG. 5) side.
  • the optical element of the present invention is used as a reflective film for a mirror with an image display function. Since the metal vapor deposition half mirror normally used for the mirror with an image display function reflects light from the display device half, the luminance is lowered.
  • the reflective polarizer of the present invention comprising a reflective film using a cholesteric liquid crystal layer can transmit linearly polarized light from a display device into circularly polarized light with a ⁇ / 4 plate, thereby allowing transmission as it is. Is twice as bright.
  • the film was longitudinally stretched at a temperature of 130 ° C., a film film surface temperature of 120 ° C., a stretching speed of 30% / min, and a stretching ratio of 35%. Thereafter, in a tenter-type stretching machine, the film is stretched transversely at a supply air temperature of 130 ° C., a film film surface temperature of 120 ° C., a stretching speed of 30% / min, and a stretching ratio of 35%, and both ends are cut off in front of the winding portion, and the length is 4000 m
  • a long temporary support having a thickness of 40 ⁇ m and a width of 1.3 m was obtained.
  • R 1 is a hydrogen atom
  • R 2 and R 3 are methyl groups.
  • An alignment layer coating solution (A) having the following composition was continuously applied to the temporary support with a # 14 wire bar. Drying was performed with warm air of 60 ° C. for 60 seconds, and further with warm air of 100 ° C. for 120 seconds. The degree of saponification of the modified polyvinyl alcohol used was 96.8%.
  • composition of coating liquid for alignment layer (A)- Denatured polyvinyl alcohol 10 parts by weight Water 308 parts by weight Methanol 70 parts by weight Isopropanol 29 parts by weight Photopolymerization initiator (IRGACURE (registered trademark) 2959, manufactured by BASF) 0.8 parts by mass
  • composition ratio of the modified polyvinyl alcohol is a molar fraction.
  • the rubbing treatment was continuously performed on the prepared alignment layer. At this time, the longitudinal direction of the long film and the transport direction were parallel, and the angle formed by the longitudinal direction of the film and the rotation axis of the rubbing roller was about 45 °.
  • a reflective polarizer (first light reflecting layer) formed by fixing a cholesteric liquid crystal phase using the following rod-like liquid crystal compound as a cholesteric liquid crystal material was formed by the following method.
  • the following coating solution is prepared so that the dry film thickness after shrinkage is 3.5 ⁇ m and dissolved in MEK (methyl ethyl ketone) to form a reflective polarizer (first light reflecting layer) containing a rod-like liquid crystal compound.
  • a coating solution was prepared.
  • the coating solution was applied onto the alignment layer with a bar and aged at 85 ° C. for 1 minute to obtain a uniform alignment state. Thereafter, this coating film was kept at 45 ° C., and irradiated with 100 mJ / cm 2 ultraviolet rays using a metal halide lamp to form a reflective polarizer.
  • Example 1- 90 parts by weight of the following rod-like compound 18-1 10 parts by weight of the following rod-like compound 18-2 0.05 parts by weight of the following fluorine-based horizontal alignment agent 1 0.01 parts by weight of the following fluorine-based horizontal alignment agent 2 polyfunctional monomer A-TMMT (new Nakamura Chemical Co., Ltd.) 1 part by weight Polymerization initiator IRGACURE819 (manufactured by BASF) 3 parts by weight The following chiral agent 1 6.3 parts by weight
  • Examples 2 to 16 The same as Example 1 except that the addition amount of the chiral agent was adjusted so that the reflection center wavelength after biaxial shrinkage was as shown in Table 1, and the biaxial shrinkage conditions were as shown in Table 1. Thus, a reflective polarizer was formed.
  • the reflective polarizers of Examples 1 to 16 are respectively a blue reflective layer (first light reflective layer), a green reflective layer (second light reflective layer), and a red reflective layer (third The optical elements of Examples 17 to 21 were formed by providing a reflective polarizer including a plurality of light reflective layers stacked as a light reflective layer, and further laminating a ⁇ / 4 plate and a polarizer.
  • an optical element of Example 22 including a reflective polarizer in which an infrared reflective layer (fourth light reflective layer) was further laminated on the configuration of Example 19 was produced.
  • a method for laminating the first to third light reflecting layers will be described below.
  • a second light reflecting layer and a third light reflecting layer were each formed on the temporary support.
  • a commercially available acrylic adhesive (UV-3300 manufactured by Toagosei Co., Ltd.) was applied on the second light reflecting layer.
  • the coated surface is directly bonded to the first light reflecting layer, and the adhesive is cured by irradiating ultraviolet rays with a dose of 100 mJ / cm 2 using a metal halide lamp from the temporary support side, and then the second light reflecting layer.
  • the temporary support was peeled from the layer.
  • a third light reflecting layer was bonded thereon by the same method as that for the second light reflecting layer, but the temporary support was not peeled off.
  • the obtained reflective polarizer is laminated on the temporary support in the order of the first light reflection layer, the adhesive layer, the second light reflection layer, the adhesive layer, the third light reflection layer, and the temporary support. It is a thing.
  • composition of matting agent dispersion B-1 Silica particle dispersion (average particle size 16 nm) "AEROSIL R972", manufactured by Nippon Aerosil Co., Ltd. 10.0 parts by mass-Methylene chloride 72.8 parts by mass-Methanol 3.9 parts by mass-Butanol 0.5 parts by mass-Cellulose ester solution A-1 10.3 parts by mass
  • UV absorber solution C-1 UV absorber (UV-1 below) 10.0 parts by mass UV absorber (UV-2 below) 10.0 parts by mass Methylene chloride 55.7 parts by mass Methanol 10 Part by weight-1.3 parts by weight of butanol-12.9 parts by weight of cellulose ester solution A-1
  • the cast dope film was dried on the drum by applying a drying air of 34 ° C. at 150 m 3 / min, and peeled off from the drum with a residual solvent of 150%. During peeling, 15% stretching was performed in the transport direction (longitudinal direction). Thereafter, the film is conveyed while being held by a pin tenter (pin tenter described in FIG. 3 of JP-A-4-1009) at both ends in the width direction (direction perpendicular to the casting direction) and stretched in the width direction. No processing was performed. Furthermore, it dried further by conveying between the rolls of a heat processing apparatus, and manufactured the cellulose acylate film (T1). The produced long cellulose acylate film (T1) had a residual solvent amount of 0.2%, a thickness of 80 ⁇ m, and Re and Rth at 550 nm of 0.8 nm and 64 nm, respectively.
  • ⁇ Formation of ⁇ / 4 layer F> As an alignment layer, a solution prepared by dissolving Kuraray's Poval PVA-103 in pure water and adjusting the concentration so that the dry film thickness becomes 0.5 ⁇ m was applied onto the cellulose acylate prepared above with a bar, and then 100 ° C. For 5 minutes. Further, this surface was rubbed to form an alignment layer. Subsequently, a concentration of a solute having the following composition was adjusted to a dry film thickness of 1 ⁇ m and dissolved in MEK to prepare a coating solution. This coating solution was applied onto the alignment layer with a bar, and the solvent was kept at 85 ° C. for 2 minutes to evaporate the solvent, followed by heat aging at 100 ° C.
  • this coating film was kept at 80 ° C. and irradiated with ultraviolet rays using a high pressure mercury lamp in a nitrogen atmosphere to form a ⁇ / 4 plate.
  • Discotic liquid crystal compound (Compound 1) 35 parts by mass Discotic liquid crystal compound (Compound 2) 35 parts by mass alignment aid (Compound 3) 1 part by mass alignment aid (Compound 4) 1 part by mass polymerization initiator (Compound 5) 3 Parts by mass
  • the temporary support on the first light reflection layer side is peeled off, and the cellulose support side of this ⁇ / 4 plate is pasted on the first light reflection layer of the reflective polarizer in the same manner as the light reflection layer. After the alignment, the temporary support of the third light reflecting layer was peeled off to obtain a reflective polarizer with a ⁇ / 4 plate.
  • the reflective polarizer with the ⁇ / 4 plate prepared above is bonded to one side of the polarizer prepared above so that the ⁇ / 4 plate is on the polarizer side, and the other is a commercially available cellulose as a polarizing plate protective film.
  • An acylate film “TD80UL” (manufactured by FUJIFILM Corporation) was bonded to produce an optical element. That is, the optical elements of Examples 17 to 21 include a third light reflecting layer, an adhesive layer, a second light reflecting layer, an adhesive layer, a first light reflecting layer, an adhesive layer, a ⁇ / 4 plate, an adhesive layer, It is the laminated structure laminated
  • the optical element of Example 22 has a configuration in which an infrared reflective layer (fourth light reflective layer) is further provided on the third light reflective layer side via an adhesive layer, and the second and third light components are provided. It was produced by the same method as the lamination of the reflective layer.
  • Comparative Examples 11 to 14 As shown in Table 2, the reflective polarizers of Comparative Examples 1 to 10 are respectively a blue reflective layer (first light reflective layer), a green reflective layer (second light reflective layer), and a red reflective layer (third The optical elements of Comparative Examples 11 to 13 were fabricated by laminating as the light reflecting layer) in the same manner as in Examples 17 to 21 above. Moreover, it carried out similarly to Example 22, and produced the comparative example 14 further provided with the infrared reflection layer (4th light reflection layer).
  • the in-plane retardation value Re was measured by the following method. After forming the reflective polarizer, the reflective polarizer is bonded to the glass plate with the acrylic adhesive and the temporary support is peeled off, and then the optical characteristics of each light reflective layer are measured by Axoscan spectrum measurement. Was measured. Of these, the reflection center wavelength was determined from the spectrum of “Transmittance”. The average value of “Linear Retention (nm)” at +80 nm of the obtained reflection center wavelength was defined as Re.
  • oblique Ret (50 °) was measured by the following method. Using the slow axis obtained during Re measurement as an axis, spectrum measurement was performed in the same manner as Re except that the Axoscan stage was tilted by 50 °, and optical characteristics were measured. Among them, the average value of “Linear Retention (nm)” at +80 nm of the reflection center wavelength obtained from the spectrum of “Transmittance” was defined as Ret (50 °).
  • backlight side polarizing plates for evaluation were produced as follows.
  • a commercially available cellulose acylate film “TD80UL” manufactured by FUJIFILM Corporation was bonded to both surfaces of the polarizer prepared in advance to obtain a laminate.
  • the reflective polarizer obtained in Examples 1 to 16 and Comparative Examples 1 to 10 was bonded to one surface of this laminate with the above acrylic adhesive, and the temporary support was peeled off. I got a plate. That is, the backlight-side polarizing plate for evaluation is a laminated structure of the reflective polarizer, the cellulose acylate film, the polarizer, and the cellulose acylate film of Examples 1 to 16 or Comparative Examples 1 to 10.
  • a commercially available liquid crystal display device (trade name TH-L42D2 manufactured by Panasonic Corporation) was disassembled and the backlight side polarizing plate was changed as follows to assemble a liquid crystal display device for evaluation.
  • the evaluation-use backlight side polarizing plate produced as described above was decomposed so that the reflective polarizer of Example or Comparative Example was on the backlight side.
  • the liquid crystal display device for evaluation was assembled by bonding to the cell of the liquid crystal display device.
  • Examples 17 to 22 and Comparative Examples 11 to 13 the optical elements produced in each example were bonded to the above-disassembled liquid crystal display cell so that the reflective polarizer was on the backlight side.
  • a liquid crystal display device was assembled.
  • a measuring machine (EZ-Contrast 160D, manufactured by ELDIM) was used to measure the color coordinates u′v ′ of the liquid crystal display device.
  • the measurement angle is fixed to the polar angle 50 ° direction, the azimuth angle is rotated 360 ° in increments of 15 °, the values of the color coordinates u ′, v ′ are measured, and the color change ⁇ u taking the difference between the maximum and the minimum 'v' (50 °) was calculated.
  • the value was used as an evaluation index and evaluated based on the following evaluation criteria.
  • Comparative Example 1 was used as a reference (Reference 1-1).
  • the liquid crystal display devices including the reflective polarizers that reflect green light in Examples 6 to 10, Comparative Example 6 and Comparative Example 9 were based on Comparative Example 2 (reference 1-2).
  • Comparative Example 3 was used as a reference (Reference 1-3).
  • Comparative Example 4 was used as a reference (Reference 1-4).
  • Examples 1 to 16 and Comparative Examples 1 to 10 were evaluated as follows with respect to the above criteria.
  • D Less than or equal to the oblique color change of the liquid crystal display device used as a reference
  • Examples 17 to 22 and Comparative Examples 11 to 14 were based on Comparative Example 11 (Criteria 2-1). In Example 22, Comparative Example 14 was used as a reference (Reference 2-2). Examples 17 to 22 and Comparative Examples 12 and 13 were evaluated as follows for each criterion. A: 40% or more better than the oblique color change of the standard liquid crystal display device B: 25% or more, less than 40% better than the oblique color change of the standard liquid crystal display device C: standard 10% or more and less than 25% better than the oblique color change of the liquid crystal display device D: equivalent to or less than the oblique color change of the standard liquid crystal display device
  • ⁇ Measurement method of oblique luminance> The front luminance at the time of white display of the liquid crystal display devices using the optical elements of Examples 17 to 22 and Comparative Examples 11 to 14 was measured using a measuring instrument (EZ-Contrast 160D, manufactured by ELDIM). Based on the results, evaluation was made according to the following criteria. In order to match the number of layers of the evaluation light source and the reflective polarizer, Examples 17 to 21 and Comparative Examples 12 to 13 were based on Comparative Example 11, and Example 22 was based on Comparative Example 15. Based on the results, evaluation was performed as follows.
  • A 40% or more better than the oblique luminance of the reference liquid crystal display device B: More than 25%, less than 40% better than the oblique luminance of the reference liquid crystal display device C: of the reference liquid crystal display device 10% or more and less than 25%, which is better than the oblique brightness D: It is equal to or less than the oblique brightness of the standard liquid crystal display device
  • Example 23 and 24 In the same manner as in Example 17, the reflective polarizers formed in Examples 1 to 16 were used as shown in Table 3 for the blue reflective layer (first light reflective layer) and the green reflective layer (second light, respectively).
  • a reflective polarizer including a plurality of light reflection layers is formed by laminating as a reflection layer) and a red reflection layer (third light reflection layer), and further laminated with a ⁇ / 4 plate to form the optical element of Example 23. Formed.
  • the optical element of Example 24 was further provided with an infrared reflection layer (fourth light reflection layer) between the red reflection layer and the ⁇ / 4 plate.
  • Comparative Examples 15 to 17 As in Comparative Example 11, among the reflective polarizers of Comparative Examples 1 to 10, as shown in Table 3, a blue reflective layer (first light reflective layer) and a green reflective layer (second light reflective layer), respectively. ), Forming a reflective polarizer including a plurality of light reflecting layers by laminating as a red reflecting layer (third light reflecting layer), and further laminating with a ⁇ / 4 plate to obtain the optical elements of Comparative Examples 15 and 16. Formed. Furthermore, in Comparative Example 15, the optical element of Comparative Example 17 was further provided with an infrared reflective layer (fourth light reflective layer) between the red reflective layer and the ⁇ / 4 plate.
  • each optical element of Examples 23 and 24 and Comparative Examples 15 and 16 has a ⁇ / 4 plate on the liquid crystal display device side.
  • bonding was performed so that the slow axis of the ⁇ / 4 plate and the absorption axis of the polarizing plate on the viewing side of the liquid crystal display device were 45 degrees to obtain a mirror with an image display function.
  • a measuring machine (EZ-Contrast 160D, manufactured by ELDIM) was used for measuring the color coordinates u′v ′.
  • the measurement angle is fixed to the polar angle 50 ° direction, the azimuth angle is rotated 360 ° in increments of 15 °, the values of the color coordinates u ′, v ′ are measured, and the color change ⁇ u taking the difference between the maximum and the minimum 'v' (50 °) was calculated.
  • the value was used as an evaluation index and evaluated based on the following evaluation criteria.
  • Example 23 and Comparative Example 16 were evaluated as follows using Comparative Example 15 as a reference (Criteria 3-1) and Example 24 using Comparative Example 17 as a reference (Criteria 3-2).
  • B 25 better than the oblique color change of the mirror with the image display function provided with the reference optical element %: Less than 40%
  • good C 10% or more, less than 25%, better than oblique color change of mirror with image display function equipped with reference optical element
  • D Provided with reference optical element Less than or equal to the oblique color change of the mirror with image display function
  • Example 23 and Comparative Example 16 are based on Comparative Example 15 as a standard (Criteria 3-1), and Example 24 is based on Comparative Example 17 as a standard (Criteria 3-2). It was evaluated as follows.
  • A 40% or more better than the oblique luminance of the mirror with the image display function provided with the reference optical element
  • B 25% more than the oblique luminance of the mirror with the image display function provided with the reference optical element, 40 Less than%
  • good C 10% or more and less than 25% better than the oblique luminance of the mirror with image display function provided with the reference optical element
  • D Mirror with image display function provided with the reference optical element Less than or equal to the diagonal brightness of
  • Example 19 and Example 22 show that the oblique luminance is high because each layer having a small color change amount around 50 ° is laminated.
  • the color change is reduced by shrinking the reflective polarizer produced on the temporary support by 10% to 30%. Furthermore, it can be seen that by changing the reflective polarizer produced on the temporary support to 15% to 25%, the color change is further reduced and a more preferable result can be obtained.
  • Example 25 ⁇ Two-stage curing>
  • the reflective polarizer of Example 1 was irradiated with 500 mJ / cm 2 ultraviolet rays using a metal halide lamp, and the polymerizable liquid crystal compound was further cured to produce the reflective polarizer of Example 25.
  • Re, Ret (50 °) and color change around 50 ° were measured and compared with Example 1.
  • the measured values for Example 1 and Example 25 were substantially the same, and no change in optical characteristics was observed before and after the ultraviolet irradiation.
  • the reflective polarizers of Example 1 and Example 25 were evaluated after aging for 500 hours in an environment of 60 ° C. and 90% RH.
  • Example 1 increased Ret (50 °) by 20 nm, whereas the film of Example 25 remained reduced by 1 nm, and it was confirmed that the wet heat durability of Ret (50 °) was improved.

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Abstract

Provided are: an optical element which, when incorporated in a liquid crystal display device, can improve the color variations in an oblique direction; a method for producing the optical element; and a liquid crystal display device. The optical element is provided with a reflective polarizer in which a cholesteric liquid crystal phase comprising a rod-like liquid crystal compound is immobilized, and the reflective polarizer has, at +80 nm from the reflection center wavelength, a front retardation value Re that satisfies 0 nm ≤ Re < 10 nm, and an absolute value |Ret (50°)| of the retardation value Ret in a polar angle 50° direction that satisfies |Ret (50°)| ≤ 50 nm.

Description

光学素子、光学素子の製造方法および液晶表示装置Optical element, optical element manufacturing method, and liquid crystal display device
　本発明は、光学素子、光学素子の製造方法および液晶表示装置に関する。 The present invention relates to an optical element, a method for manufacturing the optical element, and a liquid crystal display device.
　液晶表示装置（以下、ＬＣＤとも言う）などのフラットパネルディスプレイは、消費電力が小さく、省スペースの画像表示装置として年々その用途が広がっている。液晶表示装置は、バックライト（以下、ＢＬとも言う）、バックライト側偏光板、液晶セル、視認側偏光板などをこの順で設けられた構成となっている。
　近年のフラットパネルディスプレイ市場において、ＬＣＤ性能改善として省電力化、高精細化及び色再現性向上のための開発が進んでいる。これらの性能改善は特にタブレットＰＣやスマートフォンなどの小型サイズの液晶表示装置で顕著にみられる。
　一方、ＴＶ（Ｔｅｌｅｖｉｓｉｏｎ）用途を扱う大型サイズにおいては、次世代ハイビジョン（４Ｋ２Ｋ、ＥＢＵ比１００％以上）の開発が進められており、小型サイズ同様の性能改善として省電力化、高精細化及び色再現性向上のための開発が進んでいる。そのため、液晶表示装置の省電力化、高精細化、色再現性向上がますます求められている。 Flat panel displays such as liquid crystal display devices (hereinafter also referred to as LCDs) have low power consumption and are increasingly used as space-saving image display devices year by year. The liquid crystal display device has a configuration in which a backlight (hereinafter also referred to as BL), a backlight side polarizing plate, a liquid crystal cell, a viewing side polarizing plate, and the like are provided in this order.
In the flat panel display market in recent years, development for power saving, high definition, and color reproducibility is progressing as LCD performance improvement. These performance improvements are particularly noticeable in small-sized liquid crystal display devices such as tablet PCs and smartphones.
On the other hand, in the large size that handles TV (television) applications, the development of next-generation high-vision (4K2K, 100% or more of EBU) is being promoted. Development to improve reproducibility is progressing. Therefore, power saving, high definition, and improvement in color reproducibility of liquid crystal display devices are increasingly required.
　バックライトの省電力化に伴い、バックライトとバックライト側偏光板の間に反射偏光子を設けることが提案されている。反射偏光子は、あらゆる方向に振動しながら入射する光のうち、特定の偏光方向に振動する光のみを透過させて、他の偏光方向に振動する光は反射する光学素子である。これにより、反射偏光子で透過せず反射する光をリサイクルすることができ、ＬＣＤにおける光利用効率を改善できる。 With the power saving of the backlight, it has been proposed to provide a reflective polarizer between the backlight and the backlight side polarizing plate. The reflective polarizer is an optical element that transmits only light oscillating in a specific polarization direction among light incident while oscillating in all directions, and reflects light oscillating in other polarization directions. This makes it possible to recycle the light that is reflected without being reflected by the reflective polarizer, thereby improving the light utilization efficiency in the LCD.
　このような反射偏光子として、コレステリック液晶相を固定化してなる層を積層した構成が採用されている。コレステリック液晶相は、その螺旋のピッチに応じた波長での円偏光反射性を示すため、ピッチの異なる複数層を積層して反射波長領域を広帯域化することが可能である。例えば、特開平１－１３３００３号公報には、λ／４板とコレステリック液晶相を固定化してなる層を積層した構成の反射偏光板、コレステリック液晶相のピッチの異なる３層以上のコレステリック液晶相を固定化してなる層により、反射波長領域を広帯域化することで、ＢＬの光利用率を向上させる技術が記載されている。 As such a reflective polarizer, a structure in which layers formed by fixing a cholesteric liquid crystal phase are laminated is employed. Since the cholesteric liquid crystal phase exhibits circularly polarized light reflectivity at a wavelength corresponding to the helical pitch, it is possible to widen the reflection wavelength region by laminating a plurality of layers having different pitches. For example, Japanese Patent Application Laid-Open No. 1-133003 discloses a reflective polarizing plate having a structure in which a λ / 4 plate and a layer in which a cholesteric liquid crystal phase is fixed are laminated, and three or more cholesteric liquid crystal phases having different cholesteric liquid crystal phase pitches. A technique for improving the light utilization factor of BL by broadening the reflection wavelength region by using a fixed layer is described.
　ここで、λ／４板とコレステリック液晶相を固定化してなる層を積層した構成の反射偏光板を液晶表示装置に組み込んだときには、コレステリック液晶相及びλ／４板の光学的特性に起因する、斜め方向から見た際の色味変化が発生しやすいことが知られている。
　これに対し、特許第３５１８６６０号公報ではコレステリック液晶相のピッチを光の入射側を短ピッチにする方法、及び面内の屈折率よりも垂直方向の屈折率の大きい補償層を設けることが提案されている。また、国際公開第２００８／０１６０５６号ではλ／４板の厚み方向のレターデーションを０未満にする方法が提案されている。 Here, when a reflective polarizing plate having a structure in which a λ / 4 plate and a layer in which a cholesteric liquid crystal phase is fixed is laminated is incorporated in a liquid crystal display device, the optical characteristics of the cholesteric liquid crystal phase and the λ / 4 plate are caused. It is known that color changes are likely to occur when viewed from an oblique direction.
On the other hand, Japanese Patent No. 3518660 proposes a method in which the pitch of the cholesteric liquid crystal phase is made short on the light incident side, and a compensation layer having a refractive index larger in the vertical direction than the in-plane refractive index. ing. In addition, International Publication No. 2008/016056 proposes a method in which the retardation in the thickness direction of the λ / 4 plate is less than zero.
　その他のコレステリック液晶相を固定化してなる層を用いた偏光板としては、反射帯域を広帯域化するために、ピッチの異なる層を多数設ける方法、または、徐々にピッチを変化させる方法が提案されている。 As other polarizing plates using a layer formed by fixing a cholesteric liquid crystal phase, a method of providing a large number of layers having different pitches or a method of gradually changing the pitch has been proposed in order to broaden the reflection band. Yes.
　また、光学異方性化合物が螺旋状に配向したコレステリック配向の方向が膜面に対して一定角度を持って配向した均一チルト配向にするために、フィルム基材を加熱することによって収縮させて面に皺を生じさせて、その表面に液晶化合物などの光学異方性材料を塗布して光学機能膜を形成する方法が特開２００９－１５２００号公報に提案されている。 In addition, in order to obtain a uniform tilt orientation in which the direction of the cholesteric orientation in which the optically anisotropic compound is oriented spirally is oriented at a certain angle with respect to the film surface, the surface is contracted by heating the film substrate. Japanese Laid-Open Patent Publication No. 2009-15200 proposes a method of forming an optical functional film by generating wrinkles on the surface and applying an optically anisotropic material such as a liquid crystal compound on the surface thereof.
　上記のように、コレステリック液晶相を固定化してなる層とλ／４板を組み合わせた偏光板を用いた液晶表示装置は、ＢＬ光の光利用効率改善には寄与するものの、昨今の液晶表示装置における省電力化、高精細化及び色再現性向上の観点から、斜め色味変化についてはさらに高いレベルでの改善が要求される。このように、液晶表示装置における斜め色味変化を改善することが可能な新たな部材の開発が望まれる。 As described above, a liquid crystal display device using a polarizing plate in which a layer formed by fixing a cholesteric liquid crystal phase and a λ / 4 plate contributes to the improvement of light utilization efficiency of BL light. From the viewpoint of power saving, high definition, and color reproducibility improvement, an oblique color change is required to be improved at a higher level. Thus, it is desired to develop a new member capable of improving the oblique color change in the liquid crystal display device.
　本発明は、上記事情に鑑みてなされたものであり、液晶表示装置に組み込んだときに、斜め色味変化を改善することが可能な光学素子、光学素子の製造方法およびその光学素子を備えた液晶表示装置を提供することを目的とする。 The present invention has been made in view of the above circumstances, and includes an optical element capable of improving oblique color change when incorporated in a liquid crystal display device, a method for manufacturing the optical element, and the optical element. An object is to provide a liquid crystal display device.
　液晶表示装置において、斜め色味変化が生じる原因は、斜め方向の透過光が液晶のコレステリック配向による位相差によって、楕円偏光となり、λ／４板を透過する光全てを直線偏光に変換できないことに起因する。配向を固定した液晶相の屈折率楕円体は、通常、基板の配向規制方向に自発的に配列するため、液晶の材料に固有となる。コレステリック液晶相を固定化した反射偏光層においては、面内位相差はゼロ（ｎｘ＝ｎｙ）であるが、これらに垂直な方向の屈折率ｎｚが、ｎｘ＝ｎｙ＜ｎｚ、またはｎｘ＝ｎｙ＞ｎｚである、異方性の屈折率楕円体を有する。したがって、赤色反射層、緑色反射層、および青色反射層を積層してなる反射偏光板とした場合、それぞれの反射層において透過光の低下および波長シフトが生じ、その結果、斜め輝度の低下および斜め色味変化が生じる。 In the liquid crystal display device, the oblique color change is caused by the fact that the transmitted light in the oblique direction becomes elliptically polarized light due to the phase difference due to the cholesteric alignment of the liquid crystal, and all the light transmitted through the λ / 4 plate cannot be converted into linearly polarized light. to cause. Since the refractive index ellipsoid of the liquid crystal phase with the fixed orientation is usually arranged spontaneously in the orientation regulating direction of the substrate, it is inherent to the liquid crystal material. In the reflective polarizing layer in which the cholesteric liquid crystal phase is fixed, the in-plane retardation is zero (nx = ny), but the refractive index nz in the direction perpendicular thereto is nx = ny <nz or nx = ny>. It has an anisotropic refractive index ellipsoid that is nz. Therefore, when the reflective polarizing plate is formed by laminating the red reflective layer, the green reflective layer, and the blue reflective layer, the transmitted light is reduced and the wavelength is shifted in each reflective layer. A color change occurs.
　上述のように、従来、配向を固定した液晶相の屈折率は固定されており、収縮をしても変化がないと考えられていた。しかし、本発明者らの鋭意検討の結果、棒状液晶化合物のコレステリック液晶相を固定化した層を二軸収縮することによって、等方的な屈折率楕円体を有するフィルムを得ることができることを見出した。等方的な屈折率楕円体を有するフィルムとすることによって、斜め方向の透過光の円偏光を崩さず、λ／４板を透過する時に円偏光を直線偏光へと良好に変換することができる。その結果、斜め色味変化を高いレベルで改善できる。
　すなわち、上記課題は、以下の本発明によって解決される。 As described above, conventionally, the refractive index of the liquid crystal phase with fixed orientation is fixed, and it has been considered that there is no change even when contracted. However, as a result of intensive studies by the present inventors, it has been found that a film having an isotropic refractive index ellipsoid can be obtained by biaxially contracting a layer in which a cholesteric liquid crystal phase of a rod-like liquid crystal compound is fixed. It was. By forming a film having an isotropic refractive index ellipsoid, circularly polarized light can be satisfactorily converted into linearly polarized light when transmitted through the λ / 4 plate without breaking the circularly polarized light of obliquely transmitted light. . As a result, the oblique color change can be improved at a high level.
That is, the said subject is solved by the following this invention.
　本発明の光学素子は、棒状液晶化合物からなるコレステリック液晶相が固定化された反射偏光子を備え、
　反射偏光子は、反射中心波長の＋８０ｎｍにおいて、正面レターデーション値Ｒｅが０ｎｍ≦Ｒｅ＜１０ｎｍであり、かつ極角５０°方向のレターデーション値Ｒｅｔの絶対値｜Ｒｅｔ（５０°）｜が、｜Ｒｅｔ（５０°）｜≦５０ｎｍである。
　ここで、「正面」とは、反射偏光子の面に垂直な方向（法線方向）を意味する。また、極角５０°とは反射偏光子の面と直交する軸（法線）に対して５０°傾いた方向を意味する。
　なお、本明細書では、極角５０°のレターデーション値Ｒｅｔを、簡略のため、斜めＲｅｔ（５０°）と記載する場合がある。 The optical element of the present invention includes a reflective polarizer in which a cholesteric liquid crystal phase composed of a rod-like liquid crystal compound is fixed,
The reflective polarizer has a front retardation value Re of 0 nm ≦ Re <10 nm at a reflection center wavelength of +80 nm, and an absolute value | Ret (50 °) | of the retardation value Ret in the polar angle 50 ° direction is | Ret (50 °) | ≦ 50 nm.
Here, “front” means a direction (normal direction) perpendicular to the surface of the reflective polarizer. The polar angle of 50 ° means a direction inclined by 50 ° with respect to an axis (normal line) orthogonal to the plane of the reflective polarizer.
In this specification, the retardation value Ret having a polar angle of 50 ° may be described as an oblique Ret (50 °) for the sake of simplicity.
　反射偏光子は、第一の光反射層、第二の光反射層および第三の光反射層を含んでなり、
　第一の光反射層、第二の光反射層および第三の光反射層のうち、いずれか一つが反射中心波長３８０～４９９ｎｍかつ半値幅１００ｎｍ以下である反射率のピークを有する青色反射層であり、いずれか一つが反射中心波長５００～５９９ｎｍかつ半値幅２００ｎｍ以下である反射率のピークを有する緑色反射層であり、いずれか一つが反射中心波長６００～７５０ｎｍかつ半値幅１５０ｎｍ以下である反射率のピークを有する赤色反射層であることが好ましい。 The reflective polarizer comprises a first light reflecting layer, a second light reflecting layer, and a third light reflecting layer,
Any one of the first light reflection layer, the second light reflection layer, and the third light reflection layer is a blue reflection layer having a reflectance peak having a reflection center wavelength of 380 to 499 nm and a half width of 100 nm or less. Any one is a green reflective layer having a reflectance peak having a reflection center wavelength of 500 to 599 nm and a half-value width of 200 nm or less, and any one is a reflectance having a reflection center wavelength of 600 to 750 nm and a half-value width of 150 nm or less A red reflective layer having a peak of
　本発明の光学素子は、反射偏光子の少なくとも一方の面にλ／４板を備えることが好ましい。 The optical element of the present invention preferably includes a λ / 4 plate on at least one surface of the reflective polarizer.
　本発明の光学素子の製造方法は、棒状液晶化合物からなるコレステリック液晶相が固定化された反射偏光子を備えた光学素子の製造方法であって、
　ポリマー主鎖がフィルム面内方向に配向している支持体上に棒状液晶化合物を含む重合性組成物から塗膜を形成する工程、
　塗膜を硬化させる工程、および
　硬化させた塗膜を支持体と一緒に二軸収縮する工程により反射偏光子を形成するものである。 The method for producing an optical element of the present invention is a method for producing an optical element comprising a reflective polarizer in which a cholesteric liquid crystal phase composed of a rod-like liquid crystal compound is fixed,
Forming a coating film from a polymerizable composition containing a rod-like liquid crystal compound on a support having a polymer main chain oriented in the film in-plane direction;
The reflective polarizer is formed by a step of curing the coating film and a step of biaxially shrinking the cured coating film together with the support.
　また、二軸収縮する工程が、支持体の４辺のうち各々の辺の収縮倍率が１５％以上２５％以下になるように収縮させることが好ましい。 In addition, it is preferable that the biaxial contraction process is performed so that the contraction magnification of each of the four sides of the support is 15% or more and 25% or less.
　本発明の液晶表示装置は、少なくとも、本発明の光学素子と、液晶セルと、バックライトユニットとを備える。 The liquid crystal display device of the present invention includes at least the optical element of the present invention, a liquid crystal cell, and a backlight unit.
　本発明の光学素子は、棒状液晶化合物からなるコレステリック液晶相が固定化された反射偏光子を備え、反射偏光子が、反射中心波長の＋８０ｎｍにおいて、正面レターデーション値Ｒｅが０ｎｍ≦Ｒｅ＜１０ｎｍであり、かつ極角５０°方向のレターデーション値Ｒｅｔの絶対値｜Ｒｅｔ（５０°）｜が、｜Ｒｅｔ（５０°）｜≦５０ｎｍである。
　このような光学素子は、光学的に等方性の反射偏光子を有するものであるため、この反射偏光子に斜め入射した光に位相差を生じさせないので、斜め透過光の円偏光を崩すことがない。したがって、この斜め透過光に液晶表示装置に組み込んだときに、斜め色味変化を低減することができる。
　また、本発明の光学素子の製造方法によれば、反射中心波長の＋８０ｎｍにおいて、正面レターデーション値Ｒｅが０ｎｍ≦Ｒｅ＜１０ｎｍであり、かつ極角５０°方向のレターデーション値Ｒｅｔの絶対値｜Ｒｅｔ（５０°）｜が、｜Ｒｅｔ（５０°）｜≦５０ｎｍである反射偏光子を有する光学素子を得ることができる。
　また、本発明の液晶表示装置によれば、反射中心波長の＋８０ｎｍにおいて、正面レターデーション値Ｒｅが０ｎｍ≦Ｒｅ＜１０ｎｍであり、かつ極角５０°方向のレターデーション値Ｒｅｔの絶対値｜Ｒｅｔ（５０°）｜が、｜Ｒｅｔ（５０°）｜≦５０ｎｍである反射偏光子を備えた光学素子を有するため、斜め方向の透過光の円偏光を崩すことがないので、λ／4板でその円偏光の大部分を直線偏光に変換することができる。したがって
、斜め色味変化を低減することができる。さらには、赤色、緑色、および青色のそれぞれにおいて透過率の低下や波長シフトが生じないため、斜め輝度に優れる。 The optical element of the present invention includes a reflective polarizer in which a cholesteric liquid crystal phase composed of a rod-like liquid crystal compound is fixed. When the reflective polarizer has a reflection center wavelength of +80 nm, the front retardation value Re is 0 nm ≦ Re <10 nm. And the absolute value | Ret (50 °) | of the retardation value Ret in the polar angle 50 ° direction is | Ret (50 °) | ≦ 50 nm.
Since such an optical element has an optically isotropic reflective polarizer, it does not cause a phase difference in light obliquely incident on the reflective polarizer, so that the circularly polarized light of obliquely transmitted light is broken. There is no. Therefore, when the oblique transmitted light is incorporated into the liquid crystal display device, the oblique color change can be reduced.
Further, according to the method of manufacturing an optical element of the present invention, the front retardation value Re is 0 nm ≦ Re <10 nm at the reflection center wavelength of +80 nm, and the absolute value of the retardation value Ret in the polar angle 50 ° direction | An optical element having a reflective polarizer in which Ret (50 °) | is | Ret (50 °) | ≦ 50 nm can be obtained.
Further, according to the liquid crystal display device of the present invention, the front retardation value Re is 0 nm ≦ Re <10 nm at the reflection center wavelength of +80 nm, and the absolute value | Ret () of the retardation value Ret in the polar angle 50 ° direction. 50 °) | has an optical element with a reflective polarizer satisfying | Ret (50 °) | ≦ 50 nm, so that circular polarization of transmitted light in an oblique direction is not broken. Most of the circularly polarized light can be converted to linearly polarized light. Therefore, the diagonal color change can be reduced. Furthermore, since the transmittance and the wavelength shift do not occur in each of red, green, and blue, the oblique luminance is excellent.
本発明の光学素子の一実施形態を示す概略断面図である。It is a schematic sectional drawing which shows one Embodiment of the optical element of this invention. 本発明の反射偏光子の二軸収縮前後の屈折率楕円体を示す図である。It is a figure which shows the refractive index ellipsoid before and behind biaxial contraction of the reflective polarizer of this invention. 本発明の光学素子の他の実施形態を示す概略断面図である。It is a schematic sectional drawing which shows other embodiment of the optical element of this invention. 本発明の光学素子の製造方法における製造過程を示す図である。It is a figure which shows the manufacture process in the manufacturing method of the optical element of this invention. 本発明の液晶表示装置の一実施形態を示す概略構成図である。It is a schematic block diagram which shows one Embodiment of the liquid crystal display device of this invention. 本発明の液晶表示装置の他の実施形態を示す概略構成図である。It is a schematic block diagram which shows other embodiment of the liquid crystal display device of this invention.
　以下、本発明について詳細に説明する。
　以下に記載する構成要件の説明は、本発明の代表的な実施態様に基づくが、本発明はそのような実施態様に限定されるものではない。
　本明細書において「～」を用いて表される数値範囲は、「～」の前後に記載される数値を下限値および上限値として含む範囲を意味する。
　本明細書中、ピークの「半値幅」とは、ピーク高さ１／２でのピークの幅のことを意味する。 Hereinafter, the present invention will be described in detail.
The description of the constituent elements described below is based on typical embodiments of the present invention, but the present invention is not limited to such embodiments.
In this specification, a numerical range expressed using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.
In the present specification, the “half width” of a peak means the width of the peak at a peak height of 1/2.
　反射偏光子の反射中心波長と半値幅は積分反射計により測定することができる。ここでは、積分反射計として、分光光度計Ｖ－５５０に積分球装置ＩＬＶ－４７１（共に日本分光株式会社製）を接続したものを用いて測定する。最も大きいピーク高さを基準として１／２の高さの透過率となる２つの波長のうち、短波側の波長の値をλ１（ｎｍ）、長波側の波長の値をλ２（ｎｍ）とすると、反射中心波長と半値幅は下記式で表すことができる。
　反射中心波長＝（λ１＋λ２）／２
　半値幅＝（λ２－λ１） The reflection center wavelength and the half-value width of the reflective polarizer can be measured with an integral reflectometer. Here, measurement is performed using a spectrophotometer V-550 connected to an integrating sphere device ILV-471 (both manufactured by JASCO Corporation) as an integrating reflectometer. Of the two wavelengths having a transmittance of 1/2 height with respect to the largest peak height, the wavelength value on the short wave side is λ1 (nm) and the wavelength value on the long wave side is λ2 (nm). The reflection center wavelength and the half width can be expressed by the following equations.
Reflection center wavelength = (λ1 + λ2) / 2
Half width = (λ2-λ1)
　本発明において、Ｒｅ（λ）、Ｒｔｈ（λ）は各々、波長λにおける面内レターデーションおよび厚さ方向レターデーションを表す。
　本発明において、レターデーションＲｅ（λ）、Ｒｔｈ（λ）はＡｘｏＳｃａｎ（Ａｘｏｍｅｔｒｉｃ社製）を用いて求めるものとする。面内レターデーションＲｅ（λ）は、フィルム面の法線方向から波長λの光を入射させて測定した値である。なお、ＡｘｏＳｃａｎにて平均屈折率（（Ｎｘ＋Ｎｙ＋Ｎｚ）／３）と膜厚（ｄ（μｍ））を入力することにより、
　遅相軸方向（°）
　厚さ方向の位相差Ｒｔｈ（λ）＝（（Ｎｘ＋Ｎｙ）／２－Ｎｚ）×ｄ
が算出される。
また、斜めレターデーションＲｅｔ（５０°）は、フィルム面に極角５０°から波長λの光を入射させて測定した値である。 In the present invention, Re (λ) and Rth (λ) each represent in-plane retardation and thickness direction retardation at wavelength λ.
In the present invention, the retardations Re (λ) and Rth (λ) are obtained by using AxoScan (manufactured by Axometric). The in-plane retardation Re (λ) is a value measured by making light having a wavelength λ incident from the normal direction of the film surface. By inputting the average refractive index ((Nx + Ny + Nz) / 3) and film thickness (d (μm)) with AxoScan,
Slow axis direction (°)
Thickness direction retardation Rth (λ) = ((Nx + Ny) / 2−Nz) × d
Is calculated.
The oblique retardation Ret (50 °) is a value measured by making light having a wavelength λ from a polar angle of 50 ° incident on the film surface.
　本明細書において、斜めレターデーション値Ｒｅｔ（５０°）は、極角５０°、すなわちフィルム面の法線方向から傾けた角度θが５０°におけるレターデーションの測定値である。
　また、斜めレターデーション値Ｒｅｔ（５０°）の符号は、その遅相軸をフィルム面と平行方向と見なしたときのレターデーションの符合とする。例えば、遅相軸がフィルム面と平行方向にあると見なせる場合（例えばＲｔｈ＞０のＣプレート）は斜めレターデーション値Ｒｅｔ（５０°）の符号は正であり、遅相軸がフィルム面と垂直方向にあると見なせる場合（例えばＲｔｈ＜０のＣプレート）は斜めレターデーション値Ｒｅｔ（５０°）の符号は負となる。 In this specification, the oblique retardation value Ret (50 °) is a measured value of retardation when the polar angle is 50 °, that is, the angle θ inclined from the normal direction of the film surface is 50 °.
The sign of the oblique retardation value Ret (50 °) is the sign of the retardation when the slow axis is regarded as a direction parallel to the film surface. For example, when it can be considered that the slow axis is parallel to the film surface (for example, C plate of Rth> 0), the sign of the oblique retardation value Ret (50 °) is positive, and the slow axis is perpendicular to the film surface. When it can be regarded as being in the direction (for example, C plate of Rth <0), the sign of the oblique retardation value Ret (50 °) is negative.
　なお、本明細書では、「可視光」とは、３８０ｎｍ～７８０ｎｍのことをいう。
　また、本明細書において、角度（例えば「９０°」等の角度）、およびその関係（例えば「直交」、「平行」、および「４５°で交差」等）については、本発明が属する技術分野において許容される誤差の範囲を含むものとする。例えば、厳密な角度±１０°未満の範囲内であることなどを意味し、厳密な角度との誤差は、５°以下であることが好ましく、３°以下であることがより好ましい。 In the present specification, “visible light” means 380 nm to 780 nm.
In the present specification, the angle (for example, an angle such as “90 °”) and the relationship thereof (for example, “orthogonal”, “parallel”, “intersection at 45 °”, etc.) The range of allowable error is included. For example, it means that the angle is within the range of strict angle ± 10 °, and the error from the strict angle is preferably 5 ° or less, and more preferably 3 ° or less.
　本明細書において、偏光子または偏光板の「吸収軸」は、吸光度の最も高い方向を意味する。「透過軸」は、「吸収軸」と９０°の角度をなす方向を意味する。
　本明細書において、位相差フィルム等の「遅相軸」は、屈折率が最大となる方向を意味する。
　なお、本明細書において、「偏光子」と「反射偏光子」は区別して用いられる。
　また、本明細書において、位相差領域、位相差フィルム、および液晶層等の各部材の光学特性を示す数値、数値範囲、および定性的な表現（例えば、「同等」、「等しい」等の表現）については、液晶表示装置やそれに用いられる部材について一般的に許容される誤差を含む数値、数値範囲および性質を示していると解釈されるものとする。 In the present specification, the “absorption axis” of a polarizer or a polarizing plate means a direction having the highest absorbance. The “transmission axis” means a direction that forms an angle of 90 ° with the “absorption axis”.
In the present specification, the “slow axis” of a retardation film or the like means a direction in which the refractive index is maximized.
In this specification, “polarizer” and “reflection polarizer” are used separately.
Further, in the present specification, numerical values, numerical ranges, and qualitative expressions (for example, “equivalent”, “equal”, etc.) indicating optical characteristics of each member such as a retardation region, a retardation film, and a liquid crystal layer are used. ) Shall be interpreted to indicate numerical values, numerical ranges and properties including generally allowable errors for liquid crystal display devices and members used therefor.
＜＜光学素子＞＞
　本発明の光学素子について説明する。図１は、本発明の光学素子の一実施形態を示す概略断面図である。本発明の光学素子は、本実施形態に限定されるものではない。 << Optical element >>
The optical element of the present invention will be described. FIG. 1 is a schematic cross-sectional view showing an embodiment of the optical element of the present invention. The optical element of the present invention is not limited to this embodiment.
　図１に示すように、本発明の一実施形態の光学素子１０は、反射偏光子１３が、接着層２０を介して、λ／４板１２に積層されてなるものである。反射偏光子１３は、棒状液晶化合物からなるコレステリック液晶相が固定化されたものであり、反射中心波長の＋８０ｎｍにおいて、正面レターデーション値Ｒｅが０ｎｍ≦Ｒｅ＜１０ｎｍであり、かつ極角５０°方向のレターデーション値Ｒｅｔの絶対値｜Ｒｅｔ（５０°）｜が、｜Ｒｅｔ（５０°）｜≦５０ｎｍである。
　なお、本発明の反射偏光子１３は、コレステリック液晶相が固定化されてなる光学膜を二軸収縮して得られる二軸収縮膜により構成される。 As shown in FIG. 1, an optical element 10 according to an embodiment of the present invention includes a reflective polarizer 13 laminated on a λ / 4 plate 12 with an adhesive layer 20 interposed therebetween. The reflective polarizer 13 is obtained by fixing a cholesteric liquid crystal phase composed of a rod-like liquid crystal compound. The front retardation value Re is 0 nm ≦ Re <10 nm at the reflection center wavelength of +80 nm, and the polar angle is in the direction of 50 °. The absolute value | Ret (50 °) | of the retardation value Ret is | Ret (50 °) | ≦ 50 nm.
The reflective polarizer 13 of the present invention is constituted by a biaxially contracted film obtained by biaxially contracting an optical film in which a cholesteric liquid crystal phase is fixed.
　本発明の光学素子は反射偏光子を有し、反射偏光子に含まれるコレステリック液晶相を固定化してなる光反射層は、右円偏光または左円偏光の少なくとも一方をその反射中心波長の近傍の波長帯域において反射することができるものである。
　正面レターデーション値Ｒｅは、好ましくは、０ｎｍ≦Ｒｅ＜５ｎｍであり、かつ極角５０°方向のレターデーション値Ｒｅｔの絶対値｜Ｒｅｔ（５０°）｜は、｜Ｒｅｔ（５０°）｜≦３０ｎｍである。さらに好ましくは、０ｎｍ≦Ｒｅ＜３ｎｍであり、かつ、｜Ｒｅｔ（５０°）｜≦１０ｎｍである。 The optical element of the present invention has a reflective polarizer, and the light reflective layer formed by fixing the cholesteric liquid crystal phase contained in the reflective polarizer has at least one of right circularly polarized light and left circularly polarized light in the vicinity of its reflection center wavelength. It can be reflected in the wavelength band.
The front retardation value Re is preferably 0 nm ≦ Re <5 nm, and the absolute value | Ret (50 °) | of the retardation value Ret in the polar angle 50 ° direction is | Ret (50 °) | ≦ 30 nm. It is. More preferably, 0 nm ≦ Re <3 nm and | Ret (50 °) | ≦ 10 nm.
　本発明の光学素子は、上記のような範囲の正面レターデーション値および斜めレターデーション値を有するため、斜め入射する光に位相差が生じないので、液晶表示装置に組み込んだとき、斜め色味変化を抑制することができる。 Since the optical element of the present invention has a front retardation value and an oblique retardation value in the above ranges, there is no phase difference in obliquely incident light. Therefore, when incorporated in a liquid crystal display device, the oblique color change Can be suppressed.
＜反射偏光子＞
　本発明の光学素子における反射偏光子について、図２を参照しながら説明する。図２は、本発明の光学素子における反射偏光子（棒状液晶化合物からなるコレステリック液晶相が固定化された層）の二軸収縮前後の屈折率楕円体を示す図である。図２ａは、反射偏光子を二軸収縮する前の屈折率楕円体を示す。図２ｂは、反射偏光子を二軸収縮した後の屈折率楕円体を示す図である。 <Reflective polarizer>
The reflective polarizer in the optical element of the present invention will be described with reference to FIG. FIG. 2 is a diagram showing a refractive index ellipsoid before and after biaxial contraction of a reflective polarizer (a layer in which a cholesteric liquid crystal phase made of a rod-like liquid crystal compound is fixed) in the optical element of the present invention. FIG. 2a shows the refractive index ellipsoid before birefringing the reflective polarizer. FIG. 2b shows the refractive index ellipsoid after biaxial contraction of the reflective polarizer.
　図２ａに示すように、棒状液晶化合物からなるコレステリック液晶相が固定化された層を二軸収縮する前は、面内位相差はゼロ（ｎｘ＝ｎｙ）であるが、垂直方向の屈折率ｎｚは、ｎｘ＝ｎｙ＞ｎｚであり、異方性の屈折率楕円体を有する。
　一方、図２ｂに示すように、本発明の光学素子における反射偏光子は、棒状液晶化合物からなるコレステリック液晶相が固定化された層を二軸収縮することによって得られ、ｎｘ＝ｎｙ＝ｎｚとなり等方的な屈折率楕円体を有する。
　このように等方的な屈折率楕円体を有することによって、斜め方向の透過光の円偏光を崩すことがないので、液晶表示装置に組み込んだ場合、斜め色味変化を抑制することができる。 As shown in FIG. 2a, the in-plane retardation is zero (nx = ny) before the layer in which the cholesteric liquid crystal phase composed of the rod-like liquid crystal compound is fixed is biaxially contracted, but the vertical refractive index nz. Nx = ny> nz, and has an anisotropic refractive index ellipsoid.
On the other hand, as shown in FIG. 2b, the reflective polarizer in the optical element of the present invention is obtained by biaxial contraction of a layer in which a cholesteric liquid crystal phase composed of a rod-like liquid crystal compound is fixed, and nx = ny = nz. It has an isotropic refractive index ellipsoid.
By having an isotropic refractive index ellipsoid in this way, the circularly polarized light of the transmitted light in the oblique direction is not broken, and therefore, when incorporated in a liquid crystal display device, the oblique color change can be suppressed.
　次に、本発明の光学素子の他の実施形態について説明する。図３は、本発明の光学素子の他の実施形態の概略断面図である。
　図３に示すように、本実施形態の光学素子１１における反射偏光子１３は、第一の光反射層１４ａ、第二の光反射層１４ｂおよび第三の光反射層１４ｃを含んでなる。そして、第一の光反射層１４ａ、第二の光反射層１４ｂ、および第三の光反射層１４ｃの３層からなる反射偏光子１３が、接着層２０を介して、λ／４板１２に積層されている態様である。
　図３に示す態様に限られず、第一の光反射層１４ａ、第二の光反射層１４ｂ、および第三の光反射層１４ｃの３層を含む反射偏光子１３は、接着層２０を介さずλ／４板１２に直接接触していてもよい。なお、反射偏光子１３は第一の光反射層１４ａ、第二の光反射層１４ｂ、および第三の光反射層１４ｃ以外の層を有してもよい。
　図１および図３に示したλ／４板１２は、単層であっても、２層以上の積層体であってもよく、２層以上の積層体であることが好ましい。 Next, another embodiment of the optical element of the present invention will be described. FIG. 3 is a schematic cross-sectional view of another embodiment of the optical element of the present invention.
As shown in FIG. 3, the reflective polarizer 13 in the optical element 11 of the present embodiment includes a first light reflecting layer 14a, a second light reflecting layer 14b, and a third light reflecting layer 14c. Then, the reflective polarizer 13 composed of the first light reflecting layer 14a, the second light reflecting layer 14b, and the third light reflecting layer 14c is formed on the λ / 4 plate 12 via the adhesive layer 20. It is the aspect which is laminated | stacked.
The reflective polarizer 13 including the three layers of the first light reflecting layer 14a, the second light reflecting layer 14b, and the third light reflecting layer 14c is not limited to the mode shown in FIG. The λ / 4 plate 12 may be in direct contact. The reflective polarizer 13 may have a layer other than the first light reflecting layer 14a, the second light reflecting layer 14b, and the third light reflecting layer 14c.
The λ / 4 plate 12 shown in FIGS. 1 and 3 may be a single layer or a laminate of two or more layers, and is preferably a laminate of two or more layers.
　本発明の光学素子を液晶表示装置に組み込んだときに、輝度が高まるメカニズムを以下に説明する。
　本発明の光学素子では、反射偏光子に含まれる第一の光反射層、第二の光反射層および第三の光反射層のうち、いずれか一つが青色光反射層であり、いずれか一つが緑色光反射層であり、いずれか一つが赤色光反射層であることで、反射偏光子は青色光、緑色光および赤色光のそれぞれについて右円偏光または左円偏光の少なくとも一方を反射できる。また、λ／４板１２の作用により、偏光状態を円偏光から直線偏光に変換することができる。このような構成により、第一の偏光状態の円偏光（例えば、右円偏光）が反射偏光子によって実質的に反射され、一方で第二の偏光状態の円偏光（例えば、左円偏光）が実質的に反射偏光子を透過し、反射偏光子を透過した第二の偏光状態（例えば、左円偏光）の光はλ／４板１２によって直線偏光に変換される。
　さらに、後述の反射部材（導光器、光共振器と言われることもある）で反射偏光子によって実質的に反射された第一の偏光状態の光が再循環され、反射偏光子によって再度第一の偏光状態の円偏光として一部が反射され、第二の偏光状態の円偏光として残りの一部が透過することによりバックライト側での光利用率を高め、液晶表示装置の輝度を向上させることができる。
　反射偏光子から出射される光、すなわち反射偏光子の透過光および反射光の偏光状態は、例えばＡｘｏｍｅｔｒｉｃｓ社のＡｘｏｓｃａｎで偏光測定することで計測することができる。 A mechanism for increasing the luminance when the optical element of the present invention is incorporated in a liquid crystal display device will be described below.
In the optical element of the present invention, any one of the first light reflection layer, the second light reflection layer, and the third light reflection layer included in the reflective polarizer is a blue light reflection layer. One is a green light reflecting layer, and any one is a red light reflecting layer, so that the reflective polarizer can reflect at least one of right circularly polarized light and left circularly polarized light for each of blue light, green light and red light. Further, the polarization state can be converted from circularly polarized light to linearly polarized light by the action of the λ / 4 plate 12. With such a configuration, the circularly polarized light in the first polarization state (for example, right circularly polarized light) is substantially reflected by the reflective polarizer, while the circularly polarized light in the second polarization state (for example, left circularly polarized light) is substantially reflected. The light in the second polarization state (for example, left circularly polarized light) that substantially passes through the reflective polarizer and passes through the reflective polarizer is converted into linearly polarized light by the λ / 4 plate 12.
In addition, the light in the first polarization state substantially reflected by the reflective polarizer is recirculated by a reflective member (also referred to as a light guide or an optical resonator) described later, and the first polarization state is recirculated by the reflective polarizer. A part of the light is reflected as circularly polarized light in one polarization state and the other part is transmitted as circularly polarized light in the second polarization state, thereby increasing the light utilization rate on the backlight side and improving the brightness of the liquid crystal display device. Can be made.
The light emitted from the reflective polarizer, that is, the polarization state of the transmitted light and the reflected light of the reflective polarizer can be measured, for example, by measuring the polarization with an Axoscan from Axometrics.
　第一の光反射層１４ａ、第二の光反射層１４ｂおよび第三の光反射層１４ｃのうち、いずれか一つが反射中心波長３８０～４９９ｎｍかつ半値幅１００ｎｍ以下である反射率のピークを有する青色反射層であり、いずれか一つが反射中心波長５００～５９９ｎｍかつ半値幅２００ｎｍ以下である反射率のピークを有する緑色反射層であり、いずれか一つが反射中心波長６００～７５０ｎｍかつ半値幅１５０ｎｍ以下である反射率のピークを有する赤色反射層であることが好ましい。
　また、さらに、第三の光反射層１４ｃに接してさらに、反射中心波長７５０ｎｍ～８５０ｎｍかつ半値幅２００ｎｍ以下である反射率のピークを有する赤外光反射層を設けてもよい。 Any one of the first light reflection layer 14a, the second light reflection layer 14b, and the third light reflection layer 14c has a reflectance peak with a reflection center wavelength of 380 to 499 nm and a half-value width of 100 nm or less. A reflective layer, any one of which is a green reflective layer having a reflectance peak with a reflection center wavelength of 500 to 599 nm and a half width of 200 nm or less, and any one of which has a reflection center wavelength of 600 to 750 nm and a half width of 150 nm or less. A red reflective layer having a certain reflectance peak is preferred.
Further, an infrared light reflection layer having a reflectance peak having a reflection center wavelength of 750 nm to 850 nm and a half width of 200 nm or less may be provided in contact with the third light reflection layer 14c.
　本発明の光学素子の膜厚は、３～１２０μｍであることが好ましく、５～１００μｍであることがより好ましく、６～９０μｍであることが特に好ましい。 The film thickness of the optical element of the present invention is preferably 3 to 120 μm, more preferably 5 to 100 μm, and particularly preferably 6 to 90 μm.
　青色反射層は、３８０～４９９ｎｍの波長帯域に反射中心波長を有し、半値幅が１００ｎｍ以下である反射率のピークを有する。
　青色反射層の反射中心波長は、４３０～４８０ｎｍの波長帯域にあることが好ましく、４３０～４７０ｎｍの波長帯域にあることがより好ましい。
　青色反射層の反射率のピークの半値幅は１００ｎｍ以下であることが好ましく、この反射率のピークの半値幅が９０ｎｍ以下であることがより好ましく、この反射率のピークの半値幅が８０ｎｍ以下であることが特に好ましい。
　青色反射層は、５００～７５０ｎｍの波長帯域に反射率のピークを有さないことが好ましい。また、青色反射層は、５００～７５０ｎｍの平均反射率が５％以下であることが好ましい。
　青色反射層は、膜厚が２～１０μｍであることが好ましく、３～７μｍであることがより好ましい。 The blue reflective layer has a reflection peak having a reflection center wavelength in a wavelength band of 380 to 499 nm and a half width of 100 nm or less.
The reflection center wavelength of the blue reflective layer is preferably in the wavelength band of 430 to 480 nm, and more preferably in the wavelength band of 430 to 470 nm.
The full width at half maximum of the reflectivity peak of the blue reflective layer is preferably 100 nm or less, more preferably the full width at half maximum of this reflectivity peak is 90 nm or less, and the full width at half maximum of this reflectivity peak is 80 nm or less. It is particularly preferred.
The blue reflective layer preferably does not have a reflectance peak in the wavelength band of 500 to 750 nm. The blue reflective layer preferably has an average reflectance of 500 to 750 nm of 5% or less.
The blue reflective layer preferably has a thickness of 2 to 10 μm, more preferably 3 to 7 μm.
　緑色反射層は、５００～５９９ｎｍの波長帯域に反射中心波長を有し、半値幅が２００ｎｍ以下である反射率のピークを有する。
　緑色反射層の反射中心波長は、５２０～５９０ｎｍの波長帯域にあることが好ましく、５２０～５８０ｎｍの波長帯域にあることがより好ましい。
　緑色反射層の反射率のピークの半値幅は１６０ｎｍ以下であることが好ましく、この反射率のピークの半値幅が１２５ｎｍ以下であることがより好ましく、この反射率のピークの半値幅が１００ｎｍ以下であることが更に好ましく、この反射率のピークの半値幅が９５ｎｍ以下であることが特に好ましい。
　緑色反射層は、３８０～４９９ｎｍおよび６００～７５０ｎｍの波長帯域に反射率のピークを有さないことが好ましい。また、緑色反射層は、３８０～４９９ｎｍおよび６００～７５０ｎｍの平均反射率が５％以下であることが好ましい。
　緑色反射層は、膜厚が２～１０μｍであることが好ましく、３～７μｍであることがより好ましい。 The green reflective layer has a reflection peak having a reflection center wavelength in a wavelength band of 500 to 599 nm and a half width of 200 nm or less.
The reflection center wavelength of the green reflective layer is preferably in the wavelength band of 520 to 590 nm, and more preferably in the wavelength band of 520 to 580 nm.
The half width of the reflectance peak of the green reflective layer is preferably 160 nm or less, the half width of the reflectance peak is more preferably 125 nm or less, and the half width of the reflectance peak is 100 nm or less. It is more preferable that the half width of the reflectance peak is 95 nm or less.
The green reflective layer preferably has no reflectance peak in the wavelength bands of 380 to 499 nm and 600 to 750 nm. The green reflective layer preferably has an average reflectance of 380 to 499 nm and 600 to 750 nm of 5% or less.
The green reflective layer preferably has a thickness of 2 to 10 μm, more preferably 3 to 7 μm.
　赤色反射層は、６００～７５０ｎｍの波長帯域に反射中心波長を有し、半値幅が１５０ｎｍ以下である反射率のピークを有する。
　赤色反射層の反射中心波長は、６１０～６９０ｎｍの波長帯域にあることが好ましく、６１０～６６０ｎｍの波長帯域にあることがより好ましい。
　赤色反射層の反射率のピークの半値幅は１３０ｎｍ以下であることがより好ましく、この反射率のピークの半値幅が１１０ｎｍ以下であることが特に好ましく、この反射率のピークの半値幅が１００ｎｍ以下であることが特に好ましい。
　赤色反射層は、３８０～４９９ｎｍおよび５００～５９９ｎｍの波長帯域に反射率のピークを有さないことが好ましい。また、赤色反射層は、３８０～４９９ｎｍおよび５００～５９９ｎｍの平均反射率が５％以下であることが好ましい。
　赤色反射層は、膜厚が２～１０μｍであることが好ましく、３～７μｍであることがより好ましい。
　青色反射層、緑色反射層、赤色反射層のいずれも、反射率のピークの半値幅が３０ｎｍ以上あることがバックライトユニットの発光を反射するために好ましい。 The red reflective layer has a reflection peak having a reflection center wavelength in a wavelength band of 600 to 750 nm and a half width of 150 nm or less.
The reflection center wavelength of the red reflective layer is preferably in the wavelength band of 610 to 690 nm, and more preferably in the wavelength band of 610 to 660 nm.
The half width of the reflectance peak of the red reflective layer is more preferably 130 nm or less, the half width of the reflectance peak is particularly preferably 110 nm or less, and the half width of the reflectance peak is 100 nm or less. It is particularly preferred that
The red reflective layer preferably has no reflectance peak in the wavelength bands of 380 to 499 nm and 500 to 599 nm. The red reflective layer preferably has an average reflectance of 380 to 499 nm and 500 to 599 nm of 5% or less.
The red reflective layer preferably has a thickness of 2 to 10 μm, more preferably 3 to 7 μm.
All of the blue reflective layer, the green reflective layer, and the red reflective layer preferably have a half-value width of a reflectance peak of 30 nm or more in order to reflect light emitted from the backlight unit.
　上記のように構成することによって、青緑赤それぞれの反射偏光子の反射帯域を拡大することができる。この反射帯域の拡大には、コレステリック液晶相の螺旋ピッチが徐々に変化することで、広い半値幅を実現できるピッチグラジエント法を用いることができる。ピッチグラジエント法に関しては１９９５年（Ｎａｔｕｒｅ　３７８、４６７－４６９　１９９５）や特開平６－２８１８１４号公報や特許４９９０４２６号記載の方法により実現できる。三つの光反射層がいずれもコレステリック液晶相を固定化してなる反射偏光子である。 By configuring as described above, it is possible to expand the reflection band of each of the blue, green, and red reflective polarizers. For the expansion of the reflection band, a pitch gradient method capable of realizing a wide half-value width by gradually changing the helical pitch of the cholesteric liquid crystal phase can be used. The pitch gradient method can be realized by the method described in 1995 (Nature 378, 467-469 1995), Japanese Patent Application Laid-Open No. 6-281814, or Japanese Patent No. 4990426. Each of the three light reflecting layers is a reflective polarizer formed by fixing a cholesteric liquid crystal phase.
　反射率のピークを与える波長（すなわち反射中心波長）は、コレステリック液晶相を固定化してなる反射偏光子のコレステリック液晶相中の螺旋構造のピッチまたは屈折率を変えることにより調整することができるが、ピッチを変えることはキラル剤の添加量を変えることによって容易に調整可能である。具体的には富士フイルム研究報告Ｎｏ．５０（２００５年）ｐ．６０－６３に詳細な記載がある。 The wavelength giving the peak of reflectance (that is, the reflection center wavelength) can be adjusted by changing the pitch or refractive index of the helical structure in the cholesteric liquid crystal phase of the reflective polarizer formed by fixing the cholesteric liquid crystal phase. Changing the pitch can be easily adjusted by changing the amount of chiral agent added. Specifically, Fujifilm research report No. 50 (2005) p. There is a detailed description in 60-63.
　第一の光反射層、第二の光反射層および第三の光反射層において、各コレステリック液晶相の螺旋構造の螺旋方向は特に限定されるものではないが、第一の光反射層、第二の光反射層および第三の光反射層の各コレステリック液晶相の螺旋構造の螺旋方向が一致することが好ましい。これにより各層で反射される円偏光の位相状態を揃えて各波長域で異なる偏光状態となることを防止でき、光の利用効率を高めることができる。例えば、第一の光反射層、第二の光反射層および第三の光反射層において、各コレステリック液晶相が全て右螺旋構造を有し、第一の光反射層、第二の光反射層および第三の光反射層が全て右円偏光を反射中心波長において反射することが好ましい。当然、第一の光反射層、第二の光反射層および第三の光反射層において、各コレステリック液晶相が全て左螺旋構造を有し、第一の光反射層、第二の光反射層および第三の光反射層が全て左円偏光を反射中心波長において反射することも好ましい。 In the first light reflection layer, the second light reflection layer, and the third light reflection layer, the spiral direction of the helical structure of each cholesteric liquid crystal phase is not particularly limited, but the first light reflection layer, It is preferable that the spiral directions of the spiral structures of the cholesteric liquid crystal phases of the second light reflection layer and the third light reflection layer coincide. Thereby, it is possible to align the phase states of the circularly polarized light reflected by the respective layers and prevent different polarization states in the respective wavelength ranges, thereby increasing the light use efficiency. For example, in the first light reflection layer, the second light reflection layer, and the third light reflection layer, each cholesteric liquid crystal phase has a right spiral structure, and the first light reflection layer and the second light reflection layer It is preferable that all of the third light reflection layers reflect right circularly polarized light at the reflection center wavelength. Naturally, in each of the first light reflection layer, the second light reflection layer, and the third light reflection layer, each cholesteric liquid crystal phase has a left spiral structure, and the first light reflection layer and the second light reflection layer. It is also preferable that all of the third light reflecting layers reflect the left circularly polarized light at the reflection center wavelength.
　コレステリック液晶相を固定化してなる反射偏光子の製造方法としては特に制限はないが、例えば、特開平１－１３３００３号公報、特許第３４１６３０２号公報、特許第３３６３５６５号公報、特開平８－２７１７３１号公報に記載の方法を用いることができる。 There are no particular limitations on the method of manufacturing a reflective polarizer formed by fixing a cholesteric liquid crystal phase. For example, JP-A-1-133003, JP-A-3416302, JP-A-3363565, JP-A-8-271731 The method described in the publication can be used.
　本発明の光学素子における反射偏光子は、棒状液晶化合物を含む重合性組成物を硬化させ、収縮することによって形成される。ここでは、光学素子の製造に用いる重合性組成物の成分である、棒状液晶化合物、その他の成分および溶媒について説明する。 The reflective polarizer in the optical element of the present invention is formed by curing and shrinking a polymerizable composition containing a rod-like liquid crystal compound. Here, the rod-shaped liquid crystal compound, the other components and the solvent, which are components of the polymerizable composition used for the production of the optical element, will be described.
－棒状液晶化合物－
　まず、コレステリック液晶相を固定化してなる反射偏光子の材料である棒状液晶化合物について説明する。
　棒状液晶化合物としては、例えば、特表平１１－５１３０１９号公報や特開２００７－２７９６８８号公報に記載のものを好ましく用いることができるが、これらに限定されない。 -Rod-shaped liquid crystal compounds-
First, a rod-like liquid crystal compound, which is a reflective polarizer material formed by fixing a cholesteric liquid crystal phase, will be described.
As the rod-like liquid crystal compound, for example, those described in JP-A-11-513019 and JP-A-2007-279688 can be preferably used, but are not limited thereto.
　以下に、棒状液晶化合物の好ましい例を示すが、本発明はこれらに限定されるものではない。 Hereinafter, preferred examples of the rod-like liquid crystal compound are shown, but the present invention is not limited thereto.
Figure JPOXMLDOC01-appb-C000001
Figure JPOXMLDOC01-appb-C000001
－その他の成分－
　コレステリック液晶相を固定化してなる反射偏光子を形成するために用いられる重合性組成物は、棒状液晶化合物の他、キラル剤、配向制御剤、重合開始剤、および配向助剤などのその他の成分を含有していてもよい。いずれも公知の材料を利用することができる。 -Other ingredients-
The polymerizable composition used for forming the reflective polarizer formed by fixing the cholesteric liquid crystal phase is a rod-like liquid crystal compound, as well as other components such as a chiral agent, an alignment controller, a polymerization initiator, and an alignment aid. May be contained. Any known material can be used.
－溶媒－
　各反射偏光子を形成するための組成物の溶媒としては、有機溶媒が好ましく用いられる。有機溶媒の例には、アミド（例、Ｎ、Ｎ－ジメチルホルムアミド）、スルホキシド（例、ジメチルスルホキシド）、ヘテロ環化合物（例、ピリジン）、炭化水素（例、ベンゼン、ヘキサン）、アルキルハライド（例、クロロホルム、ジクロロメタン）、エステル（例、酢酸メチル、酢酸ブチル）、ケトン（例、アセトン、メチルエチルケトン、シクロヘキサノン）、エーテル（例、テトラヒドロフラン、１、２－ジメトキシエタン）が含まれる。アルキルハライドおよびケトンが好ましい。二種類以上の有機溶媒を併用してもよい。 -solvent-
As a solvent of the composition for forming each reflective polarizer, an organic solvent is preferably used. Examples of organic solvents include amides (eg N, N-dimethylformamide), sulfoxides (eg dimethyl sulfoxide), heterocyclic compounds (eg pyridine), hydrocarbons (eg benzene, hexane), alkyl halides (eg , Chloroform, dichloromethane), esters (eg, methyl acetate, butyl acetate), ketones (eg, acetone, methyl ethyl ketone, cyclohexanone), ethers (eg, tetrahydrofuran, 1,2-dimethoxyethane). Alkyl halides and ketones are preferred. Two or more organic solvents may be used in combination.
　次に、本発明の光学素子に備えられ、もしくは光学素子の製造方法において用いられる部材について説明する。 Next, members provided in the optical element of the present invention or used in the method for manufacturing an optical element will be described.
＜支持体＞
　本発明の光学素子は、支持体を含んでいてもよい。支持体は、コレステリック液晶相の層形状を維持するための機能を有し、この支持体上に反射偏光子を形成する。本発明では、本発明の光学素子に含まれるλ／４板１２（後述する）そのものを支持体として用いて、図１に示したようにλ／４板１２に反射偏光子を貼合してもよい。また、支持体上に形成されたλ／４板１２の全体を支持体として用いて、その支持体に反射偏光子を貼合してもよい。
　このような支持体としては、透明支持体が好ましく、ポリメチルメタクリレート等のポリアクリル系樹脂フィルム、セルローストリアセテート等のセルロース系樹脂フィルム、およびシクロオレフィンポリマー系フィルム［例えば、商品名「アートン」、ＪＳＲ社製、商品名「ゼオノア」、日本ゼオン社製］等を挙げることができる。 <Support>
The optical element of the present invention may include a support. The support has a function of maintaining the layer shape of the cholesteric liquid crystal phase, and a reflective polarizer is formed on the support. In the present invention, a λ / 4 plate 12 (described later) included in the optical element of the present invention itself is used as a support, and a reflective polarizer is bonded to the λ / 4 plate 12 as shown in FIG. Also good. Alternatively, the entire λ / 4 plate 12 formed on the support may be used as a support, and a reflective polarizer may be bonded to the support.
As such a support, a transparent support is preferable, a polyacrylic resin film such as polymethyl methacrylate, a cellulose resin film such as cellulose triacetate, and a cycloolefin polymer film [for example, trade name “ARTON”, JSR And the trade name “ZEONOR”, manufactured by Nippon Zeon Co., Ltd.].
　一方、本発明の光学素子は、反射偏光子を製膜する際の支持体は含んでなくてもよく、反射偏光子を製膜する際の支持体（以下において、仮支持体という。）として用い、反射偏光子を形成した後その仮支持体から反射偏光子を剥離して本発明の光学素子としてもよい。なお、本発明の光学素子は、反射中心波長が異なる第一の光反射層、第二の光反射層および第三の光反射層が含まれるが、仮支持体を用いて各光反射層を形成し、仮支持体から剥離した光反射層を積層した反射偏光子を、λ／４板１２に貼合することで本発明の光学素子とすることが好ましい。 On the other hand, the optical element of the present invention may not include a support for forming the reflective polarizer, but as a support for forming the reflective polarizer (hereinafter referred to as a temporary support). It is possible to use the optical polarizer of the present invention by forming the reflective polarizer and then peeling the reflective polarizer from the temporary support. The optical element of the present invention includes a first light reflection layer, a second light reflection layer, and a third light reflection layer having different reflection center wavelengths, and each light reflection layer is formed using a temporary support. It is preferable to form an optical element of the present invention by laminating a reflective polarizer formed by laminating a light reflecting layer formed and peeled off from a temporary support to the λ / 4 plate 12.
　このような製膜時に用いられる仮支持体としては、特に制限はないが、後述の製造工程における収縮処理および剥離等に耐えうる物性を有することが好ましい。
　収縮処理を行うために、仮支持体は、ポリマー主鎖がフィルム面内方向に配向している、すなわち面配向しているものを使用する。面配向の指標はフィルムの断面配向度Ｐ２ｚを用いる。仮支持体の断面配向度Ｐ２ｚを０．０７以上～１以下に調整することで、液晶層形成後の収縮処理工程で十分な収縮力を得ることができる。断面配向度Ｐ２ｚは０．１以上～０．３以下であることが好ましく、０．１２以上～０．２５以下であることがより好ましい。断面配向度Ｐ２ｚを０．０７以上～１以下にする方法は、ポリマー主鎖を面内方向に配向させることができればよく、二軸延伸または二軸押出し、圧延、または、溶液キャスト法などが用いられ、二軸延伸を行うことが好ましい。溶液キャスト法ではウェブ乾燥時に面積を固定することで厚み方向のみが収縮するため、主鎖を面内方向に配向させることができる。 Although there is no restriction | limiting in particular as a temporary support body used at the time of such film forming, It is preferable to have a physical property which can endure the shrinkage process, peeling, etc. in the below-mentioned manufacturing process.
In order to perform the shrinkage treatment, the temporary support is used in which the polymer main chain is oriented in the in-plane direction of the film, that is, in the plane orientation. The index of the plane orientation uses the cross-sectional orientation degree P2z of the film. By adjusting the cross-sectional orientation degree P2z of the temporary support to 0.07 or more and 1 or less, a sufficient contraction force can be obtained in the contraction treatment step after the liquid crystal layer is formed. The cross-sectional orientation degree P2z is preferably 0.1 or more and 0.3 or less, and more preferably 0.12 or more and 0.25 or less. The method of setting the cross-sectional orientation degree P2z to 0.07 or more and 1 or less is not limited as long as the polymer main chain can be oriented in the in-plane direction, and biaxial stretching or biaxial extrusion, rolling, or solution casting is used. It is preferable to perform biaxial stretching. In the solution casting method, the main chain can be oriented in the in-plane direction because only the thickness direction shrinks by fixing the area when the web is dried.
　なお、フィルムの断面配向度Ｐ２ｚは、Ｘ線回折測定より算出した下記式（１）および式（２）で定義される。
（１）Ｐ＝＜３ｃｏｓ2β－１＞／２
（２）Ｐ２ｚ＝（Ｐｘｚ＋Ｐｙｚ）／２
ただし、
（３）<cos2β>=∫(0、π)cos2βI(β)sinβdβ/∫(0、π)I(β)sinβdβ
である。
（式中、βは入射するＸ線の入射面と、測定するフィルム面内の任意の一方向とのなす角度であり、Ｉは角度βで測定したＸ線回折チャートにおける２θ＝７°以上～１１°以下での回折強度である。）
　また、Ｐｘｚはフィルムの製膜方向および面外方向に垂直な方向のＸ線回折測定から求めた上記式（１）で定義される配向度であり、Ｐｙｚはフィルムの幅手方向および面外方向に垂直な方向のＸ線回折測定から求めた上記式（１）で定義される配向度である。
　なお、Ｘ線回折測定は、透過２次元Ｘ線測定を採用し、理学電機製ＲＩＮＴ　ＲＡＰＩＤを用い、Ｘ線源にはＣｕ管球を用い、４０ｋＶ－３６ｍＡでＸ線を発生し、コリメーターは０．８ｍｍφ、フィルム試料は透過試料台を用いて固定し、露光時間は６００秒として測定される。 In addition, the cross-sectional orientation degree P2z of the film is defined by the following formula (1) and formula (2) calculated from the X-ray diffraction measurement.
(1) P = <3 cos 2β-1> / 2
(2) P2z = (Pxz + Pyz) / 2
However,
(3) <cos2β> = ∫ (0, π) cos2βI (β) sinβdβ / ∫ (0, π) I (β) sinβdβ
It is.
(Where β is the angle formed by the incident surface of the incident X-ray and an arbitrary direction in the film surface to be measured, and I is 2θ = 7 ° or more in the X-ray diffraction chart measured at angle β Diffraction intensity at 11 ° or less.)
Pxz is the degree of orientation defined by the above formula (1) obtained from the X-ray diffraction measurement in the direction perpendicular to the film forming direction and the out-of-plane direction, and Pyz is the width direction and the out-of-plane direction of the film. The degree of orientation defined by the above formula (1) obtained from the X-ray diffraction measurement in the direction perpendicular to.
The X-ray diffraction measurement employs transmission two-dimensional X-ray measurement, uses RINT RAPID manufactured by Rigaku Corporation, uses a Cu tube as the X-ray source, generates X-rays at 40 kV-36 mA, The 0.8 mmφ film sample is fixed using a transmission sample stage, and the exposure time is 600 seconds.
　仮支持体を二軸延伸により作製する場合は、公知の方法を用いることができる。
　作製したフィルムを、縦一軸延伸機において、所望の延伸倍率で縦延伸した後、テンター式延伸機において所望の延伸倍率で横延伸してもよい。または、横延伸した後、縦延伸してもよい。二軸延伸されたフィルムは、巻取り部前で両端部を切り落とし、巻き取り部で巻き取ることによってロールフィルムとしてもよい。縦横の延伸倍率は基本的に同率とするが、縦一軸延伸において幅方向に収縮した場合は初期からの実質的な変形率が同等になるように横延伸倍率を大きくしてもよい。また実質的な縦横の変形率は５％程度差であれば許容される。
　延伸時の吸気温度、フィルム膜面温度、および延伸速度は、所望の延伸倍率によって適宜調製することが可能である。 When the temporary support is produced by biaxial stretching, a known method can be used.
The produced film may be stretched longitudinally at a desired stretching ratio in a longitudinal uniaxial stretching machine and then stretched at a desired stretching ratio in a tenter stretching machine. Or you may extend | stretch longitudinally after carrying out a horizontal stretch. The biaxially stretched film may be made into a roll film by cutting off both ends before winding up and winding up at the winding up. The longitudinal and lateral stretching ratios are basically the same, but when shrinking in the width direction in longitudinal uniaxial stretching, the transverse stretching ratio may be increased so that the substantial deformation ratio from the initial stage becomes equal. A substantial vertical / horizontal deformation rate of about 5% is acceptable.
The intake air temperature, film film surface temperature, and stretching speed during stretching can be appropriately adjusted depending on the desired stretching ratio.
＜配向層＞
　反射偏光子の形成面（重合性組成物の塗布面）には、所望の液晶の配向を得るため、ここでは所望のコレステリック液晶相を得るために、配向層を備えていることが好ましい。
　配向層は、有機化合物（好ましくはポリマー）のラビング処理、無機化合物の斜方蒸着、マイクログルーブを有する層の形成等の手段で設けることができる。さらには、電場の付与、磁場の付与、或いは光照射により配向機能が生じる配向層も知られている。配向層は、ポリマーの膜の表面を、ラビング処理することにより形成することが好ましい。反射偏光子形成後に、仮支持体から反射偏光子を剥離する場合には、配向層も仮支持体と共に剥離することが好ましい。 <Alignment layer>
In order to obtain the desired liquid crystal alignment, the reflective polarizer is preferably provided with an alignment layer in order to obtain a desired cholesteric liquid crystal phase.
The alignment layer can be provided by means such as a rubbing treatment of an organic compound (preferably a polymer), oblique vapor deposition of an inorganic compound, or formation of a layer having a microgroove. Furthermore, an alignment layer in which an alignment function is generated by application of an electric field, application of a magnetic field, or light irradiation is also known. The alignment layer is preferably formed by rubbing the surface of the polymer film. When the reflective polarizer is peeled off from the temporary support after forming the reflective polarizer, the alignment layer is preferably peeled off together with the temporary support.
　支持体に用いられるポリマー種によっては、配向層を設けなくても、支持体を直接配向処理（例えば、ラビング処理）することで、配向層として機能させることもできる。そのような支持体の一例としては、ＰＥＴ（ポリエチレンテレフタレート）を挙げることができる。 Depending on the type of polymer used for the support, it is possible to cause the support to function as an orientation layer by directly subjecting the support to an orientation treatment (for example, rubbing treatment) without providing an orientation layer. An example of such a support is PET (polyethylene terephthalate).
　また、液晶層の上に直接液晶層を積層する場合、例えば、第一の光反射層上に直接、第二の光反射層を形成する場合、下層の液晶層が配向層として振舞い上層の液晶を配向させることができる場合もある。このような場合、配向層を設けなくても、また、特別な配向処理（例えば、ラビング処理）を実施しなくても上層の液晶を配向させることができる。 Also, when a liquid crystal layer is laminated directly on the liquid crystal layer, for example, when a second light reflective layer is formed directly on the first light reflective layer, the lower liquid crystal layer behaves as an alignment layer and the upper liquid crystal layer In some cases. In such a case, the upper liquid crystal can be aligned without providing an alignment layer or without performing a special alignment process (for example, rubbing process).
－ラビング処理－
　配向層または支持体の表面はラビング処理が施されることが好ましい。また、第一、第二、および第三の光反射層の表面に、必要に応じてラビング処理をすることも可能である。ラビング処理は、一般にはポリマーを主成分とする膜の表面を、紙や布で一定方向に擦ることにより実施することができる。ラビング処理の一般的な方法については、例えば、「液晶便覧」（丸善社発行、平成１２年１０月３０日）に記載されている。 -Rubbing treatment-
The surface of the alignment layer or the support is preferably subjected to a rubbing treatment. Moreover, it is also possible to carry out a rubbing treatment on the surfaces of the first, second, and third light reflecting layers as necessary. The rubbing treatment can be generally performed by rubbing the surface of a film containing a polymer as a main component with paper or cloth in a certain direction. A general method of rubbing is described in, for example, “Liquid Crystal Handbook” (issued by Maruzen, October 30, 2000).
＜λ／４板＞
　本発明の光学素子は、反射偏光子の少なくとも一方の面にλ／４板を有してもよい。
　λ／４板は、反射偏光子を通り抜けた円偏光を直線偏光に変換するための層である。同時に、厚さ方向のレターデーション（Ｒｔｈ（λ））を調節することで、斜め方位から見た場合に発生する反射偏光子の膜厚の位相差をキャンセルすることが可能となる。
　本発明の光学素子では、λ／４板のＲｔｈ（５５０）が－１２０～１２０ｎｍであることが好ましく、－８０～８０ｎｍであることがより好ましく、－７０～７０ｎｍであることが特に好ましい。 <Λ / 4 plate>
The optical element of the present invention may have a λ / 4 plate on at least one surface of the reflective polarizer.
The λ / 4 plate is a layer for converting circularly polarized light that has passed through the reflective polarizer into linearly polarized light. At the same time, by adjusting the retardation (Rth (λ)) in the thickness direction, it becomes possible to cancel the phase difference in the thickness of the reflective polarizer that occurs when viewed from an oblique direction.
In the optical element of the present invention, Rth (550) of the λ / 4 plate is preferably −120 to 120 nm, more preferably −80 to 80 nm, and particularly preferably −70 to 70 nm.
　本発明の光学素子に用いられるλ／４板の材料について特に制限はない。λ／４板は、λ／４機能を有する光学異方性支持体であってもよいし、ポリマーフィルムからなる支持体上に光学異方性層等を有してなるものであってもよい。 There is no particular limitation on the material of the λ / 4 plate used for the optical element of the present invention. The λ / 4 plate may be an optically anisotropic support having a λ / 4 function, or may have an optically anisotropic layer or the like on a support made of a polymer film. .
＜接着層（粘着剤層）＞
　本明細書において、「接着」は「粘着」も含む概念で用いられる。
　本発明の光学素子においては、λ／４板と反射偏光子は、直接接触して、または、接着層を介して積層されていることが好ましい。また、反射偏光子が複数層積層された光学素子においては、反射偏光子は直接接触して積層される形態のみならず、各反射偏光子間に接着層を介して積層されてもよい。 <Adhesive layer (adhesive layer)>
In this specification, “adhesion” is used in a concept including “adhesion”.
In the optical element of the present invention, it is preferable that the λ / 4 plate and the reflective polarizer are laminated in direct contact or via an adhesive layer. In addition, in an optical element in which a plurality of reflective polarizers are laminated, the reflective polarizers may be laminated not only in a form in which they are in direct contact with each other, but also between each reflective polarizer via an adhesive layer.
　接着層に用いられる粘着剤の例としては、ポリエステル系樹脂、エポキシ系樹脂、ポリウレタン系樹脂、シリコーン系樹脂、アクリル系樹脂等の樹脂をあげることができる。これらは単独もしくは２種以上混合して使用してもよい。特に、アクリル系樹脂は、耐水性、耐熱性、耐光性等の信頼性に優れ、接着力、透明性が良く、更に、屈折率を液晶ディスプレイに適合するように調整し易い等から好ましい。
質等が含まれる。 Examples of the pressure-sensitive adhesive used for the adhesive layer include resins such as polyester resins, epoxy resins, polyurethane resins, silicone resins, and acrylic resins. You may use these individually or in mixture of 2 or more types. In particular, an acrylic resin is preferable because it is excellent in reliability such as water resistance, heat resistance, and light resistance, has good adhesion and transparency, and can easily adjust the refractive index to be compatible with a liquid crystal display.
Quality etc. are included.
　本発明には、シート状光硬化型粘接着剤（東亞合成グループ研究年報　１１　ＴＲＥＮＤ　２０１１　第１４号記載）を接着層に用いることもできる。粘着剤のように光学フィルム同士の貼合が簡便で、紫外線（ＵＶ）で架橋・硬化し、貯蔵弾性率、接着力および耐熱性が向上するものであり、本発明に適した接着法である。 In the present invention, a sheet-like photo-curing adhesive (Toagosei Group Research Annual Report 11, TREND 2011, No. 14) can be used for the adhesive layer. Bonding between optical films is easy, like an adhesive, crosslinks and cures with ultraviolet rays (UV), improves storage elastic modulus, adhesive strength and heat resistance, and is an adhesive method suitable for the present invention. .
＜偏光子＞
　本発明の光学素子は、λ／４板と併せて偏光子を有していてもよい。ここで、偏光子は第１の直線偏光を透過し、第１の直線偏光に直交する第２の直線偏光を吸収もしくは反射する吸収型の偏光子であり、λ／４板の遅相軸と偏光子の吸収軸とのなす角が３０～６０°であることが好ましい。この偏光子は、λ／４板を挟んで反射偏光子と対向して配置される。
　偏光子としては、ポリマーフィルムにヨウ素が吸着配向されたものを用いることが好ましい。ポリマーフィルムとしては、特に限定されず各種のものを使用できる。例えば、ポリビニルアルコール系フィルム、ポリエチレンテレフタレート系フィルム、エチレン・酢酸ビニル共重合体系フィルムや、これらの部分ケン化フィルム、セルロース系フィルム等の親水性高分子フィルムに、ポリビニルアルコールの脱水処理物やポリ塩化ビニルの脱塩酸処理物等ポリエン系配向フィルム等が挙げられる。これらの中でも、偏光子としてのヨウ素による染色性に優れたポリビニルアルコール系フィルムを用いることが好ましい。 <Polarizer>
The optical element of the present invention may have a polarizer in combination with the λ / 4 plate. Here, the polarizer is an absorptive polarizer that transmits the first linearly polarized light and absorbs or reflects the second linearly polarized light orthogonal to the first linearly polarized light, and the slow axis of the λ / 4 plate and The angle formed with the absorption axis of the polarizer is preferably 30 to 60 °. This polarizer is disposed opposite to the reflective polarizer with the λ / 4 plate interposed therebetween.
As the polarizer, it is preferable to use a polymer film in which iodine is adsorbed and oriented. The polymer film is not particularly limited, and various types can be used. For example, polyvinyl alcohol films, polyethylene terephthalate films, ethylene / vinyl acetate copolymer films, partially saponified films of these, hydrophilic polymer films such as cellulose films, polyvinyl alcohol dehydrated products and polychlorinated Examples include polyene-based oriented films such as vinyl dehydrochlorinated products. Among these, it is preferable to use a polyvinyl alcohol film excellent in dyeability with iodine as a polarizer.
　偏光子の厚さとしては特に限定されず、通常は５～８０μｍ、好ましくは５～５０μｍ、より好ましくは、５～２５μｍである。 The thickness of the polarizer is not particularly limited, and is usually 5 to 80 μm, preferably 5 to 50 μm, more preferably 5 to 25 μm.
＜＜光学素子の製造方法＞＞
　本発明の光学素子の製造方法について説明する。図４は、棒状液晶化合物からなるコレステリック液晶相が固定化された反射偏光子を備えた光学素子の製造方法であって、棒状液晶化合物を含む重合性組成物から塗膜を形成する工程（１）、塗膜を硬化させてコレステリック液晶相を固定化する工程（２）、硬化させた塗膜を二軸収縮する工程（３）、および、二軸収縮した塗膜をさらに硬化させる工程（４）により反射偏光子を形成するものである。なお、（４）の工程は湿熱耐久性を向上させるために実施するのが好ましいが、（４）の工程により光学特性の変化は生じないため、使用環境によっては必ずしも実施する必要はない。
　本発明の光学素子の製造方法によれば、等方的な屈折率楕円体を有する反射偏光子を得ることができる。よって、この光学素子を液晶表示装置の組み込むことによって、斜め方向に透過する円偏光を崩すことなく、λ/４板で円偏光を良好に直線偏光に変換することができる。これにより、斜め方向の色味変化を低減することができ、さらには、良好な斜め輝度を得ることができる。 << Optical Element Manufacturing Method >>
A method for producing the optical element of the present invention will be described. FIG. 4 is a method for producing an optical element including a reflective polarizer in which a cholesteric liquid crystal phase composed of a rod-like liquid crystal compound is fixed, and a step of forming a coating film from a polymerizable composition containing a rod-like liquid crystal compound (1 ), Curing the coating film to fix the cholesteric liquid crystal phase (2), biaxially contracting the cured coating film (3), and further curing the biaxially contracted coating film (4) ) To form a reflective polarizer. Note that the step (4) is preferably performed in order to improve wet heat durability, but the optical property is not changed by the step (4), and therefore it is not necessarily performed depending on the use environment.
According to the method for manufacturing an optical element of the present invention, a reflective polarizer having an isotropic refractive index ellipsoid can be obtained. Therefore, by incorporating this optical element into a liquid crystal display device, it is possible to satisfactorily convert circularly polarized light into linearly polarized light with the λ / 4 plate without breaking circularly polarized light transmitted in an oblique direction. Thereby, the color change of the diagonal direction can be reduced and also favorable diagonal brightness | luminance can be obtained.
　（１）工程では、まず、支持体または基板等や下層の反射偏光子の表面に、棒状液晶化合物を含む重合性組成物（以下、重合性液晶組成物と記載する場合がある。）から塗膜を形成する。重合性液晶組成物は、溶媒に材料を溶解および／または分散した、塗布液として調製されるのが好ましい。塗布液の塗布は、ワイヤーバーコーティング法、押し出しコーティング法、ダイレクトグラビアコーティング法、リバースグラビアコーティング法、ダイコーティング法、等の種々の方法によって行うことができる。また、インクジェット装置を用いて、液晶組成物をノズルから吐出して、塗膜を形成することもできる。 In the step (1), first, a coating composition containing a rod-like liquid crystal compound (hereinafter may be referred to as a polymerizable liquid crystal composition) is applied to the surface of a support or a substrate or the lower reflective polarizer. A film is formed. The polymerizable liquid crystal composition is preferably prepared as a coating solution in which a material is dissolved and / or dispersed in a solvent. The coating liquid can be applied by various methods such as a wire bar coating method, an extrusion coating method, a direct gravure coating method, a reverse gravure coating method, and a die coating method. Alternatively, a liquid crystal composition can be discharged from a nozzle using an ink jet apparatus to form a coating film.
　次に、表面に塗布され、塗膜となった重合性液晶組成物を、コレステリック液晶相の状態にする。重合性液晶組成物が、溶媒を含む塗布液として調製されている態様では、塗膜を乾燥し、溶媒を除去することで、コレステリック液晶相の状態にすることができる場合がある。また、コレステリック液晶相への転移温度とするために、所望により、塗膜を加熱してもよい。例えば、一旦等方相の温度まで加熱し、その後、コレステリック液晶相転移温度（等方相とコレステリック液晶層との相転移温度）まで冷却する等によって、安定的にコレステリック液晶相の状態にすることができる。重合性液晶組成物の上記液晶相転移温度は、製造適性等の面から１０～２５０℃の範囲内であることが好ましく、１０～１５０℃の範囲内であることがより好ましい。１０℃未満であると液晶相を呈する温度範囲にまで温度を下げるために冷却工程等が必要となることがある。また、熱エネルギーの効率利用、基板の耐熱性、等からの観点から、塗膜の加熱温度は２００℃以下とすることが好ましい。このときの温度は膜面温度であり、ＯＰＴＥＸ社製ＰＴ-２ＬＤなどで測定することができる。 Next, the polymerizable liquid crystal composition applied to the surface to become a coating film is brought into a cholesteric liquid crystal phase. In the aspect in which the polymerizable liquid crystal composition is prepared as a coating solution containing a solvent, the coating film may be dried and the solvent may be removed to obtain a cholesteric liquid crystal phase. Moreover, in order to set it as the transition temperature to a cholesteric liquid crystal phase, you may heat a coating film depending on necessity. For example, by heating to an isotropic phase temperature and then cooling to a cholesteric liquid crystal phase transition temperature (phase transition temperature between the isotropic phase and the cholesteric liquid crystal layer), the cholesteric liquid crystal phase is stably formed. Can do. The liquid crystal phase transition temperature of the polymerizable liquid crystal composition is preferably in the range of 10 to 250 ° C., more preferably in the range of 10 to 150 ° C. from the viewpoint of production suitability and the like. When the temperature is lower than 10 ° C., a cooling step or the like may be required to lower the temperature to a temperature range exhibiting a liquid crystal phase. Moreover, it is preferable that the heating temperature of a coating film shall be 200 degrees C or less from a viewpoint from the efficient utilization of a thermal energy, the heat resistance of a board | substrate, etc. The temperature at this time is the film surface temperature, and can be measured with PT-2LD manufactured by OPTEX.
　コレステリック液晶相の旋回の方向は、用いる液晶の種類または添加されるキラル剤の種類によって調整でき、螺旋ピッチ（すなわち、選択反射波長）は、これらの材料の濃度によって調整できる。また、各反射偏光子の反射する特定の領域の波長は、製造方法のさまざまな要因によってシフトさせることができることが知られており、キラル剤などの添加濃度のほか、コレステリック液晶相を固定化するときの温度や照度と照射時間などの条件などでシフトさせることができる。したがって、これらの条件は、所望の反射波長に応じて決定する。 The direction of rotation of the cholesteric liquid crystal phase can be adjusted by the type of liquid crystal used or the type of chiral agent added, and the helical pitch (ie, selective reflection wavelength) can be adjusted by the concentration of these materials. In addition, it is known that the wavelength of a specific region reflected by each reflective polarizer can be shifted depending on various factors of the manufacturing method. In addition to the concentration of a chiral agent or the like, the cholesteric liquid crystal phase is immobilized. It can be shifted depending on conditions such as temperature, illuminance, and irradiation time. Therefore, these conditions are determined according to the desired reflection wavelength.
　次に、（２）の工程では、コレステリック液晶相の状態となった塗膜に、紫外線を照射して、硬化反応を進行させる。紫外線照射には、紫外線ランプ等の光源が利用される。この工程では、紫外線を照射することによって、重合性液晶組成物の硬化反応が進行し、コレステリック液晶相が固定化される。
　紫外線の照射エネルギー量については特に制限はないが、一般的には、１０ｍＪ／ｃｍ2～２００ｍＪ／ｃｍ2程度が好ましく、２０ｍＪ／ｃｍ2～１００ｍＪ／ｃｍ2程度がより好ましい。また、塗膜に紫外線を照射する時間については特に制限はないが、（３）の工程の二軸収縮に適した硬化状態を得られる時間を設定すればよい。 Next, in the step (2), the coating film in the cholesteric liquid crystal phase is irradiated with ultraviolet rays to advance the curing reaction. For ultraviolet irradiation, a light source such as an ultraviolet lamp is used. In this step, the curing reaction of the polymerizable liquid crystal composition proceeds by irradiating with ultraviolet rays, and the cholesteric liquid crystal phase is fixed.
No particular limitation is imposed on the amount of irradiation energy of ultraviolet rays, in general, preferably about 10mJ / cm 2 ~ 200mJ / cm 2, 20mJ / cm 2 ~ 100mJ / cm 2 approximately is more preferable. Moreover, there is no restriction | limiting in particular about the time which irradiates a coating film with an ultraviolet-ray, However, What is necessary is just to set time which can obtain the hardening state suitable for the biaxial shrinkage | contraction of the process of (3).
　硬化反応を促進するため、加熱条件下で紫外線照射を実施してもよい。また、紫外線照射時の温度は、コレステリック液晶相が乱れないように、コレステリック液晶相を呈する温度範囲に維持するのが好ましい。また、雰囲気の酸素濃度は重合度に関与するため、空気中で所望の重合度に達せず、膜強度が不充分の場合には、窒素置換等の方法により、雰囲気中の酸素濃度を低下させることが好ましい。好ましい酸素濃度としては、１０％以下が好ましく、７％以下がさらに好ましく、３％以下が最も好ましい。紫外線照射によって進行される硬化反応（例えば重合反応）の反応率は、次の工程（３）で二軸収縮時にコレステリック液晶層に起伏が生じて皺が寄るのを抑え、かつ、層の機械的強度の保持等や未反応物が層から流出するのを抑える等の観点から、２５％～７０％であることが好ましく、３０％～６０％であることがより好ましい。反応率の測定は反応性基（例えば重合性基）の赤外振動スペクトルの吸収強度を、反応進行の前後で比較することによって行うことができる。反応率を向上させるためには照射する紫外線の照射量を増大する方法や窒素雰囲気下あるいは加熱条件下での重合が効果的である。 In order to accelerate the curing reaction, ultraviolet irradiation may be performed under heating conditions. Moreover, it is preferable to maintain the temperature at the time of ultraviolet irradiation in the temperature range which exhibits a cholesteric liquid crystal phase so that a cholesteric liquid crystal phase may not be disturbed. Also, since the oxygen concentration in the atmosphere is related to the degree of polymerization, if the desired degree of polymerization is not reached in the air and the film strength is insufficient, the oxygen concentration in the atmosphere is reduced by a method such as nitrogen substitution. It is preferable. A preferable oxygen concentration is preferably 10% or less, more preferably 7% or less, and most preferably 3% or less. The reaction rate of the curing reaction (for example, polymerization reaction) proceeded by ultraviolet irradiation is such that the cholesteric liquid crystal layer is prevented from wrinkling due to biaxial shrinkage in the next step (3), and the mechanical properties of the layer are reduced. From the standpoint of maintaining strength and suppressing unreacted substances from flowing out of the layer, it is preferably 25% to 70%, more preferably 30% to 60%. The reaction rate can be measured by comparing the absorption intensity of the infrared vibration spectrum of a reactive group (for example, a polymerizable group) before and after the reaction proceeds. In order to improve the reaction rate, a method of increasing the irradiation amount of ultraviolet rays to be irradiated and polymerization under a nitrogen atmosphere or heating conditions are effective.
　（３）の工程では、（２）で得られた硬化させた層を二軸収縮する。
　二軸収縮は、公知の方法を用いることができる。
　作製したコレステリック液晶相の塗膜を有するフィルムを、バッチ延伸機で４辺をテンターで固定し、加熱して、熱収縮させる。１０％／分～１００％／分の収縮速度で収縮させるのが好ましい。収縮倍率は、テンターの固定位置で決定され、所望の収縮倍率にあわせてテンターの固定位置を設定することで、給気温度およびフィルム膜面温度が同じであっても異なる収縮倍率に調整することが可能である。また、縦横の収縮倍率は基本的に同率とするが、実質的な縦横の変形率は５％程度差であれば許容される。
　収縮時の給気温度、フィルム膜面温度、および収縮速度は、所望の収縮倍率によって適宜調整することが可能である。
　収縮時のフィルム膜面温度はコレステリック液晶相を形成した支持体のガラス転移点Ｔｇ－１０～Ｔｇ＋２０℃が好ましく、Ｔｇ－５℃～Ｔｇ＋１５℃がより好ましい。 In the step (3), the cured layer obtained in (2) is biaxially contracted.
A known method can be used for the biaxial contraction.
The produced film having a coating film of a cholesteric liquid crystal phase is fixed by a tenter on four sides with a batch stretching machine, heated, and thermally contracted. It is preferable to contract at a contraction rate of 10% / min to 100% / min. The shrinkage ratio is determined by the tenter's fixed position. By setting the tenter's fixed position according to the desired shrinkage ratio, the shrinkage ratio can be adjusted to be different even if the supply air temperature and film film surface temperature are the same. Is possible. The vertical and horizontal shrinkage ratios are basically the same, but the substantial vertical and horizontal deformation ratios are allowed if they differ by about 5%.
The air supply temperature at the time of shrinkage, the film film surface temperature, and the shrinkage speed can be appropriately adjusted according to a desired shrinkage ratio.
The film surface temperature during shrinkage is preferably the glass transition point Tg-10 to Tg + 20 ° C., more preferably Tg-5 ° C. to Tg + 15 ° C. of the support on which the cholesteric liquid crystal phase is formed.
　（４）の工程では、（３）で収縮した層にさらに紫外線を照射して、硬化反応を進行させる。（２）に工程と同様に、紫外線を照射することによって、重合性液晶組成物をさらに硬化させて、固定化したコレステリック液晶相の湿熱耐久性を向上させることができる。なお、紫外線の照射前後で光学特性の変化は生じない。
　紫外線の照射エネルギー量については特に制限はないが、一般的には、１００ｍＪ／ｃｍ2～１０００ｍＪ／ｃｍ2程度が好ましく、２００ｍＪ／ｃｍ2～５００ｍＪ／ｃｍ2程度がより好ましい。さらに、硬化反応を促進するため、加熱条件および雰囲気の条件は、（２）の工程と同様である。また、紫外線照射によって進行される硬化反応（例えば重合反応）の反応率は、層の機械的強度の保持等や未反応物が層から流出するのを抑える等の観点から、７０％以上であることが好ましく、８０％以上であることがより好ましく、９０％以上であることがよりさらに好ましい。 In the step (4), the layer contracted in (3) is further irradiated with ultraviolet rays to advance the curing reaction. Similarly to the step (2), by irradiating with ultraviolet rays, the polymerizable liquid crystal composition can be further cured to improve the wet heat durability of the immobilized cholesteric liquid crystal phase. Note that the optical characteristics do not change before and after the irradiation with ultraviolet rays.
No particular limitation is imposed on the amount of irradiation energy of ultraviolet rays, in general, 100 mJ / cm is preferably 2 ~ 1000mJ / cm 2 approximately, 200mJ / cm 2 ~ 500mJ / cm 2 approximately is more preferable. Furthermore, in order to accelerate the curing reaction, the heating conditions and the atmospheric conditions are the same as in the step (2). Further, the reaction rate of the curing reaction (for example, polymerization reaction) proceeded by ultraviolet irradiation is 70% or more from the viewpoint of maintaining the mechanical strength of the layer and suppressing unreacted substances from flowing out of the layer. Preferably, it is 80% or more, more preferably 90% or more.
　ここで、液晶相を「固定化した」状態は、コレステリック液晶相となっている液晶化合物の配向が保持された状態が最も典型的、且つ好ましい態様である。本発明では、紫外線照射によって進行する硬化反応により、コレステリック液晶相の配向状態を固定することが好ましい。
　また、具体的には、０℃～５０℃においてこの層に流動性が無く、また外場や外力によって配向形態に変化を生じさせることなく、固定化された配向形態を安定に保ち続けることができる状態とするのが好ましい。さらに、より過酷な条件下では－３０℃～７０℃の温度範囲において、固定化された配向形態を安定に保ち続けることができる状態にするのが好ましい。
　なお、本発明においては、コレステリック液晶相の光学的性質が層中において保持されていれば充分であり、最終的に各反射偏光子中の液晶組成物がもはや液晶性を示す必要はない。例えば、液晶組成物が、硬化反応により高分子量化して、もはや液晶性を失っていてもよい。
　また、「実質的な縦横の変形率は５％程度差であれば許容される。」とは、縦が１０％収縮したときに、横が１５％収縮する、という程度には許容することができる、あるいは、縦が１５％収縮したときに、横が１０％収縮する、という程度には許容することができることを意味する。 Here, the state in which the liquid crystal phase is “fixed” is the most typical and preferred mode in which the orientation of the liquid crystal compound in the cholesteric liquid crystal phase is maintained. In the present invention, the alignment state of the cholesteric liquid crystal phase is preferably fixed by a curing reaction that proceeds by ultraviolet irradiation.
Specifically, this layer does not have fluidity at 0 ° C. to 50 ° C., and can maintain a fixed orientation form stably without causing a change in the orientation form due to an external field or an external force. It is preferable to be in a ready state. Furthermore, it is preferable that the fixed orientation form can be kept stable in a temperature range of −30 ° C. to 70 ° C. under more severe conditions.
In the present invention, it is sufficient that the optical properties of the cholesteric liquid crystal phase are maintained in the layer, and the liquid crystal composition in each reflective polarizer no longer needs to exhibit liquid crystal properties. For example, the liquid crystal composition may have a high molecular weight due to a curing reaction and may no longer have liquid crystallinity.
In addition, “substantially a vertical and horizontal deformation ratio of about 5% is allowable” means that when the vertical contraction is 10%, the horizontal contraction is 15%. This means that it can be tolerated to the extent that when the vertical contraction is 15%, the horizontal contraction is 10%.
＜＜液晶表示装置＞＞
　本発明の液晶表示装置について説明する。図５は、本発明の液晶表示装置の一実施形態を示す概略構成図である。
　本実施形態の液晶表示装置５１は、図５に示すように、バックライトユニット３１、本発明の光学素子１１を含む光学シート部材２１、薄層トランジスタ基板４１、液晶セル４２、カラーフィルター基板４３、および表示側偏光板４４を備える。光学シート部材２１は、本発明の光学素子１１が接着層２０を介してバックライト側偏光板１に接着されてなる。バックライト側偏光板１は、偏光板保護フィルム４が設けられた偏光子３および位相差フィルム２から構成される。
　バックライトユニット３１は、４３０～４８０ｎｍの波長帯域に発光中心波長を有する青色光と、５００～６００ｎｍの波長帯域に発光中心波長を有する緑色光と、６００～７００ｎｍの波長帯域に発光強度のピークの少なくとも一部を有する赤色光とを発光する光源を備えることが好ましい。
　さらに、バックライトユニット３１が、バックライトユニット３１から出力されて光学素子１１で反射された光の偏光状態の変換および反射をする反射部材を備えることが好ましい。 << Liquid Crystal Display >>
The liquid crystal display device of the present invention will be described. FIG. 5 is a schematic configuration diagram showing an embodiment of the liquid crystal display device of the present invention.
As shown in FIG. 5, the liquid crystal display device 51 of this embodiment includes a backlight unit 31, an optical sheet member 21 including the optical element 11 of the present invention, a thin layer transistor substrate 41, a liquid crystal cell 42, a color filter substrate 43, And a display-side polarizing plate 44. The optical sheet member 21 is formed by bonding the optical element 11 of the present invention to the backlight side polarizing plate 1 through the adhesive layer 20. The backlight side polarizing plate 1 includes a polarizer 3 and a retardation film 2 provided with a polarizing plate protective film 4.
The backlight unit 31 has blue light having an emission center wavelength in the wavelength band of 430 to 480 nm, green light having an emission center wavelength in the wavelength band of 500 to 600 nm, and peaks of emission intensity in the wavelength band of 600 to 700 nm. It is preferable to provide a light source that emits at least a part of red light.
Furthermore, it is preferable that the backlight unit 31 includes a reflecting member that converts and reflects the polarization state of the light output from the backlight unit 31 and reflected by the optical element 11.
　また、本発明の液晶表示装置は、青色光および緑色光の半値幅がいずれも１００ｎｍ以下であることが好ましい。本発明の液晶表示装置は、赤色光が６００～７００ｎｍの波長帯域に発光中心波長を有し、赤色光の半値幅が１００ｎｍ以下であることが好ましい。本発明の液晶表示装置の一部であるこれらのような態様では、ＲＧＢ（赤緑青）狭帯域バックライトと組み合わせることで、色再現性を向上させながら、ＲＧＢの光反射層であるコレステリック液晶相を固定化してなる反射偏光子およびλ／４板というシンプルな構成の上記実施形態の光学素子１１により充分な輝度向上性能を実現することができる。 Further, in the liquid crystal display device of the present invention, it is preferable that the full width at half maximum of blue light and green light is 100 nm or less. In the liquid crystal display device of the present invention, it is preferable that red light has an emission center wavelength in a wavelength band of 600 to 700 nm, and a half-value width of red light is 100 nm or less. In such an embodiment which is a part of the liquid crystal display device of the present invention, the cholesteric liquid crystal phase which is an RGB light reflection layer is improved while combining with an RGB (red, green and blue) narrow-band backlight while improving color reproducibility. A sufficient brightness enhancement performance can be realized by the optical element 11 of the above-described embodiment having a simple configuration of a reflective polarizer and a λ / 4 plate.
　液晶表示装置において、光学素子の第三の光反射層とバックライトユニットの間には、光の偏光状態を変化させる層を配置することが、好ましい。光の偏光状態を変化させる層が反射偏光子から反射された光の偏光状態を変化させる層として機能し、輝度を向上させることができるからである。光の偏光状態を変化させる層の例としては、空気層より屈折率が高いポリマー層が挙げられ、空気層より屈折率が高いポリマー層の例としては、ハードコート（HC）処理層、アンチグレア（AG）処理層、低反射（AR）処理層などの各種低反射層、トリアセチルセルロース（TAC）フィルム、アクリル樹脂フィルム、シクロオレフ
ィンポリマー（COP）樹脂フィルム、延伸ＰＥＴフィルム等が挙げられる。光の偏光状態を変化させる層は支持体を兼ねていてもよい。 In the liquid crystal display device, it is preferable to dispose a layer that changes the polarization state of light between the third light reflection layer of the optical element and the backlight unit. This is because the layer that changes the polarization state of the light functions as a layer that changes the polarization state of the light reflected from the reflective polarizer, and the luminance can be improved. Examples of the layer that changes the polarization state of light include a polymer layer having a refractive index higher than that of the air layer. Examples of the polymer layer having a refractive index higher than that of the air layer include a hard coat (HC) treatment layer, an antiglare ( Various low reflection layers such as AG) treatment layer and low reflection (AR) treatment layer, triacetyl cellulose (TAC) film, acrylic resin film, cycloolefin polymer (COP) resin film, stretched PET film and the like. The layer that changes the polarization state of light may also serve as a support.
　反射偏光子から反射された光の偏光状態を変化させる層の平均屈折率と、第三の光反射層の平均屈折率の関係は、
０＜｜光の偏光状態を変化させる層の平均屈折率－第三の光反射層の平均屈折率｜＜０．８であることが好ましく、
０＜｜光の偏光状態を変化させる層の平均屈折率－第三の光反射層の平均屈折率｜＜０．４であることがさらに好ましく
０＜｜光の偏光状態を変化させる層の平均屈折率－第三の光反射層の平均屈折率｜＜０．２がより好ましい。
　光の偏光状態を変化させる層は光学素子と一体化していてもよく、光学素子とは別に設けられていてもよい。 The relationship between the average refractive index of the layer that changes the polarization state of the light reflected from the reflective polarizer and the average refractive index of the third light reflecting layer is:
Preferably, 0 <| average refractive index of the layer that changes the polarization state of light−average refractive index of the third light reflecting layer | <0.8,
0 <| average refractive index of the layer that changes the polarization state of light−an average refractive index of the third light reflecting layer | <0.4 is more preferable 0 <| the average of the layer that changes the polarization state of light Refractive index−average refractive index of the third light reflecting layer | <0.2 is more preferable.
The layer that changes the polarization state of the light may be integrated with the optical element or may be provided separately from the optical element.
＜液晶セル＞
　液晶セル４２の駆動モードについては特に制限はなく、ツイステットネマチック（ＴＮ）、スーパーツイステットネマチック（ＳＴＮ）、バーティカルアライメント（ＶＡ）、インプレインスイッチング（ＩＰＳ）、オプティカリーコンペンセイテットベンドセル（ＯＣＢ）等の種々のモードを利用することができる。液晶セルは、ＶＡモード、ＯＣＢモード、ＩＰＳモード、またはＴＮモードであることが好ましいが、これらに限定されるものではない。ＶＡモードの液晶表示装置の構成としては、特開２００８－２６２１６１号公報の図２に示す構成が一例として挙げられる。ただし、液晶表示装置の具体的構成には特に制限はなく、公知の構成を採用することができる。 <Liquid crystal cell>
The driving mode of the liquid crystal cell 42 is not particularly limited, and is twisted nematic (TN), super twisted nematic (STN), vertical alignment (VA), in-plane switching (IPS), optically compensated bend cell (OCB). ) And other modes can be used. The liquid crystal cell is preferably VA mode, OCB mode, IPS mode, or TN mode, but is not limited thereto. As an example of the configuration of the VA mode liquid crystal display device, the configuration shown in FIG. However, the specific configuration of the liquid crystal display device is not particularly limited, and a known configuration can be adopted.
＜バックライトユニット＞
　バックライトユニットの構成としては、導光板や反射板などを構成部材とするエッジライト方式であっても、直下型方式であっても構わない。
　本発明の液晶表示装置は、バックライトユニットが光源の後部に、光源から発光されて光学素子で反射された光の偏光状態の変換および反射をする反射部材を備える。このような反射部材としては特に制限は無く、公知のものを用いることができ、特許第３４１６３０２号、特許第３３６３５６５号、特許第４０９１９７８号、特許第３４４８６２６号などに記載されており、これらの公報の内容は本発明に組み込まれる。 <Backlight unit>
The configuration of the backlight unit may be an edge light method using a light guide plate or a reflection plate as a constituent member, or a direct type.
In the liquid crystal display device of the present invention, the backlight unit includes a reflection member at the rear portion of the light source for converting and reflecting the polarization state of the light emitted from the light source and reflected by the optical element. There is no restriction | limiting in particular as such a reflecting member, A well-known thing can be used, and it is described in patent 3416302, patent 3363565, patent 4091978, patent 3448626, etc., These gazettes Are incorporated into the present invention.
　バックライトユニットは、その他、公知の拡散板や拡散シート、プリズムシート（例えば、３Ｍ社製輝度向上フィルム「ＢＥＦ」など）、導光器を備えていることも好ましい。その他の部材についても、特許第３４１６３０２号、特許第３３６３５６５号、特許第４０９１９７８号、特許第３４４８６２６号などに記載されており、これらの公報の内容は本発明に組み込まれる。 The backlight unit preferably further includes a known diffusion plate, diffusion sheet, prism sheet (for example, 3M brightness enhancement film “BEF”), and a light guide. Other members are also described in Japanese Patent No. 3416302, Japanese Patent No. 3363565, Japanese Patent No. 4091978, Japanese Patent No. 3448626, and the contents of these publications are incorporated in the present invention.
　本発明の液晶表示装置の他の形態について説明する。図６に本実施形態の液晶表示装置の概略構成を示す。
　本実施形態の液晶表示装置６０は、上記の液晶表示装置５１の表示面（最も視認側）にさらに光学素子１１を備えた構成である。なお、光学素子１１の下方には液晶表示装置５１に限らず、他の形態の液晶表示装置を備えてもよい。
　本実施形態では、光学素子１１はλ／４が表示側偏光板４４（図５参照）側となるように配置される。 Another embodiment of the liquid crystal display device of the present invention will be described. FIG. 6 shows a schematic configuration of the liquid crystal display device of the present embodiment.
The liquid crystal display device 60 of the present embodiment has a configuration in which the optical element 11 is further provided on the display surface (most visible side) of the liquid crystal display device 51 described above. Note that the liquid crystal display device 51 is not limited to the liquid crystal display device 51 below the optical element 11, and other types of liquid crystal display devices may be provided.
In the present embodiment, the optical element 11 is arranged so that λ / 4 is on the display side polarizing plate 44 (see FIG. 5) side.
　ここでは、本発明の光学素子は画像表示機能付きミラー用反射膜として使用される。画像表示機能付きミラーに通常使用されている金属蒸着ハーフミラーは、表示装置側からの光も半分反射してしまうため、輝度が低下してしまう。それに対し、コレステリック液晶層を用いる反射膜からなる本発明の反射偏光子は表示装置からの直線偏光をλ／４板で円偏光に変換することで、そのまま透過させることができ、金属蒸着ハーフミラーの二倍の輝度が得られる。 Here, the optical element of the present invention is used as a reflective film for a mirror with an image display function. Since the metal vapor deposition half mirror normally used for the mirror with an image display function reflects light from the display device half, the luminance is lowered. On the other hand, the reflective polarizer of the present invention comprising a reflective film using a cholesteric liquid crystal layer can transmit linearly polarized light from a display device into circularly polarized light with a λ / 4 plate, thereby allowing transmission as it is. Is twice as bright.
　従来の収縮することなく用いられていたこれまでのコレステリック液晶層では画像表示機能付ミラー用反射膜として利用しようとしても、コレステリック層の有する斜めレターデーションにより円偏光が崩れ、波長ごとの透過率が変わり、色味が変化してしまうという問題があった。しかし、本発明の光学素子ならば斜めレターデーションが小さいため色味変化無く高輝度な表示が可能となる。 Even if the conventional cholesteric liquid crystal layer used without shrinking is used as a reflective film for a mirror with an image display function, the circularly polarized light is broken by the oblique retardation of the cholesteric layer, and the transmittance for each wavelength is reduced. There was a problem that the color changed. However, with the optical element of the present invention, since the oblique retardation is small, it is possible to display with high brightness without any change in color.
　以下に実施例と比較例を挙げて本発明の特徴をさらに具体的に説明する。以下の実施例に示す材料、使用量、割合、処理内容、処理手順等は、本発明の趣旨を逸脱しない限り適宜変更することができる。したがって、本発明の範囲は以下に示す具体例により限定的に解釈されるべきものではない。 Hereinafter, the features of the present invention will be described more specifically with reference to examples and comparative examples. The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples shown below.
＜偏光子の準備＞
　特開２００６－２９３２７５号公報の［０２１９］と同様にして、偏光子を製造した。 <Preparation of polarizer>
A polarizer was produced in the same manner as [0219] of JP-A-2006-293275.
［実施例１］
＜仮支持体の作製＞
　［下記一般式（ＩＩ）で表されるラクトン環構造を有するアクリル系樹脂｛共重合モノマー質量比＝メタクリル酸メチル／２－（ヒドロキシメチル）アクリル酸メチル＝８／２、ラクトン環化率約１００％、ラクトン環構造の含有割合１９．４％、重量平均分子量１３３０００、メルトフローレート６．５ｇ／１０分（２４０℃、１０ｋｇｆ）、Ｔｇ１３１℃｝９０質量部と、アクリロニトリル－スチレン（ＡＳ）樹脂｛トーヨーＡＳ　ＡＳ２０、東洋スチレン社製｝１０質量部との混合物；Ｔｇ１２７℃］のペレットを二軸押出機に供給し、約２８０℃でシート状に溶融押出しした後、縦一軸延伸機において、給気温度１３０℃、フィルム膜面温度１２０℃、延伸速度３０％／分、延伸倍率３５％で縦延伸した。その後、テンター式延伸機において、給気温度１３０℃、フィルム膜面温度１２０℃、延伸速度３０％／分、延伸倍率３５％で横延伸し、巻取り部前で両端部を切り落とし、長さ４０００ｍのロールフィルムとして巻き取りして、厚さ４０μｍ、幅１．３ｍの長尺状の仮支持体を得た。 [Example 1]
<Preparation of temporary support>
[Acrylic resin having a lactone ring structure represented by the following general formula (II) {mass ratio of copolymerization monomer = methyl methacrylate / 2- (hydroxymethyl) methyl acrylate = 8/2, lactone cyclization rate of about 100 %, Lactone ring structure content 19.4%, weight average molecular weight 133000, melt flow rate 6.5 g / 10 min (240 ° C., 10 kgf), Tg 131 ° C.} 90 parts by mass, acrylonitrile-styrene (AS) resin { Toyo AS AS20, manufactured by Toyo Styrene Co., Ltd.} mixture of 10 parts by weight; Tg127 ° C.] pellets were fed into a twin screw extruder, melt extruded into a sheet at about 280 ° C., and then fed into a longitudinal uniaxial stretcher. The film was longitudinally stretched at a temperature of 130 ° C., a film film surface temperature of 120 ° C., a stretching speed of 30% / min, and a stretching ratio of 35%. Thereafter, in a tenter-type stretching machine, the film is stretched transversely at a supply air temperature of 130 ° C., a film film surface temperature of 120 ° C., a stretching speed of 30% / min, and a stretching ratio of 35%, and both ends are cut off in front of the winding portion, and the length is 4000 m As a roll film, a long temporary support having a thickness of 40 μm and a width of 1.3 m was obtained.
Figure JPOXMLDOC01-appb-C000002
 
Figure JPOXMLDOC01-appb-C000002
 
　上記一般式（ＩＩ）中、Ｒ１は水素原子であり、Ｒ２およびＲ３はメチル基である。 In the general formula (II), R 1 is a hydrogen atom, and R 2 and R 3 are methyl groups.
＜配向層の形成＞
　上記仮支持体に、下記組成の配向層塗布液（Ａ）を＃１４のワイヤーバーで連続的に塗布した。６０℃の温風で６０秒、更に１００℃の温風で１２０秒乾燥した。使用した変性ポリビニルアルコールの鹸化度は９６．８％であった。 <Formation of alignment layer>
An alignment layer coating solution (A) having the following composition was continuously applied to the temporary support with a # 14 wire bar. Drying was performed with warm air of 60 ° C. for 60 seconds, and further with warm air of 100 ° C. for 120 seconds. The degree of saponification of the modified polyvinyl alcohol used was 96.8%.
－配向層塗布液（Ａ）の組成－
　下記の変性ポリビニルアルコール　　　　　　　　　　　　１０質量部
　水　　　　　　　　　　　　　　　　　　　　　　　　　３０８質量部
　メタノール　　　　　　　　　　　　　　　　　　　　　　７０質量部
　イソプロパノール　　　　　　　　　　　　　　　　　　　２９質量部
　光重合開始剤（ＩＲＧＡＣＵＲＥ（登録商標）２９５９、ＢＡＳＦ社製）
　　　　　　　　　　　　　　　　　　　　　　　　　　　０．８質量部 -Composition of coating liquid for alignment layer (A)-
Denatured polyvinyl alcohol 10 parts by weight Water 308 parts by weight Methanol 70 parts by weight Isopropanol 29 parts by weight Photopolymerization initiator (IRGACURE (registered trademark) 2959, manufactured by BASF)
0.8 parts by mass
Figure JPOXMLDOC01-appb-C000003
 
　変性ポリビニルアルコールの組成割合は、モル分率である。
Figure JPOXMLDOC01-appb-C000003

The composition ratio of the modified polyvinyl alcohol is a molar fraction.
　上記作製した配向層に連続的にラビング処理を施した。このとき、長尺状のフィルムの長手方向と搬送方向は平行であり、フィルム長手方向とラビングローラーの回転軸とのなす角度を略４５°とした。 The rubbing treatment was continuously performed on the prepared alignment layer. At this time, the longitudinal direction of the long film and the transport direction were parallel, and the angle formed by the longitudinal direction of the film and the rotation axis of the rubbing roller was about 45 °.
＜反射偏光子の形成＞
　配向層上に、下記の方法でコレステリック液晶材料として下記棒状液晶化合物を用いたコレステリック液晶相を固定化してなる反射偏光子（第一の光反射層）を形成した。
　下記の塗布液を、収縮後の乾燥膜厚が３．５μｍになるように濃度を調製してＭＥＫ（メチルエチルケトン）に溶解し、棒状液晶化合物を含む反射偏光子（第一の光反射層）形成用の塗布液を調製した。この塗布液を上記の配向層上にバー塗布して、８５℃で１分間加熱熟成を行って、均一な配向状態を得た。その後、この塗布膜を４５℃に保持し、これにメタルハライドランプを用いて１００ｍＪ／ｃｍ2紫外線照射して、反射偏光子を形成した。 <Formation of reflective polarizer>
On the alignment layer, a reflective polarizer (first light reflecting layer) formed by fixing a cholesteric liquid crystal phase using the following rod-like liquid crystal compound as a cholesteric liquid crystal material was formed by the following method.
The following coating solution is prepared so that the dry film thickness after shrinkage is 3.5 μm and dissolved in MEK (methyl ethyl ketone) to form a reflective polarizer (first light reflecting layer) containing a rod-like liquid crystal compound. A coating solution was prepared. The coating solution was applied onto the alignment layer with a bar and aged at 85 ° C. for 1 minute to obtain a uniform alignment state. Thereafter, this coating film was kept at 45 ° C., and irradiated with 100 mJ / cm 2 ultraviolet rays using a metal halide lamp to form a reflective polarizer.
－実施例１の反射偏光子用塗布液－
　下記棒状化合物１８－１　　　　　　　　　　　　　　　　９０質量部
　下記棒状化合物１８－２　　　　　　　　　　　　　　　　１０質量部
　下記フッ素系水平配向剤１　　　　　　　　　　　　　０．０５質量部
　下記フッ素系水平配向剤２　　　　　　　　　　　　　０．０１質量部
　多官能モノマーＡ－ＴＭＭＴ（新中村化学工業（株）社製）　１質量部
　重合開始剤ＩＲＧＡＣＵＲＥ８１９（ＢＡＳＦ社製）　　　　３質量部
　下記キラル剤１　　　　　　　　　　　　　　　　　　　６．３質量部 -Coating liquid for reflective polarizer of Example 1-
90 parts by weight of the following rod-like compound 18-1 10 parts by weight of the following rod-like compound 18-2 0.05 parts by weight of the following fluorine-based horizontal alignment agent 1 0.01 parts by weight of the following fluorine-based horizontal alignment agent 2 polyfunctional monomer A-TMMT (new Nakamura Chemical Co., Ltd.) 1 part by weight Polymerization initiator IRGACURE819 (manufactured by BASF) 3 parts by weight The following chiral agent 1 6.3 parts by weight
Figure JPOXMLDOC01-appb-C000004
 
Figure JPOXMLDOC01-appb-C000004
 
Figure JPOXMLDOC01-appb-C000005
 
Figure JPOXMLDOC01-appb-C000006
 
Figure JPOXMLDOC01-appb-C000005
 
Figure JPOXMLDOC01-appb-C000006
 
＜二軸収縮コレステリック液晶フィルムの作製＞
　仮支持体上に作製した反射偏光子の４辺をテンターで固定し、バッチ延伸機において、給気温度１４０℃、フィルム膜面温度１３０℃、収縮速度３０％／分でフィルムの各辺がそれぞれ表１記載の収縮倍率（１０％）になるよう収縮した。その後４辺の端部を切り落とし、二軸収縮コレステリック液晶フィルムを得て反射偏光子とした。 <Production of biaxially contracted cholesteric liquid crystal film>
The four sides of the reflective polarizer produced on the temporary support were fixed with a tenter, and in the batch stretching machine, the sides of the film were each at an air supply temperature of 140 ° C., a film film surface temperature of 130 ° C., and a shrinkage rate of 30% / min. It shrunk | reduced so that it might become shrinkage | contraction magnification (10%) of Table 1. Thereafter, the ends of the four sides were cut off to obtain a biaxially contracted cholesteric liquid crystal film to obtain a reflective polarizer.
［実施例２～１６］
　二軸収縮後の反射中心波長が表１に記載のものとなるようにキラル剤の添加量を調整し、さらに二軸収縮条件を表１に記載のようにした以外は、実施例１と同様にして反射偏光子を形成した。 [Examples 2 to 16]
The same as Example 1 except that the addition amount of the chiral agent was adjusted so that the reflection center wavelength after biaxial shrinkage was as shown in Table 1, and the biaxial shrinkage conditions were as shown in Table 1. Thus, a reflective polarizer was formed.
［比較例１～１０］
　最終的な反射中心波長が表１に記載のものとなるようにキラル剤の添加量を調整し、さらに表１のように、収縮なし、一軸収縮、二軸延伸を行った以外は、実施例１と同様にして反射偏光子を形成した。 [Comparative Examples 1 to 10]
Except for adjusting the addition amount of the chiral agent so that the final reflection center wavelength is as shown in Table 1, and further performing no shrinkage, uniaxial shrinkage, and biaxial stretching as shown in Table 1, Examples In the same manner as in Example 1, a reflective polarizer was formed.
［実施例１７～２２］
　実施例１～１６の反射偏光子を、表２に示すように、それぞれ、青色反射層（第一の光反射層）、緑色反射層（第二の光反射層）、赤色反射層（第三の光反射層）として積層して複数層の光反射層を含む反射偏光子を備え、さらにλ／４板および偏光子を積層してなる実施例１７～２１の光学素子を形成した。また、実施例１９の構成にさらに赤外反射層（第四の光反射層）を積層した反射偏光子を備えた実施例２２の光学素子を作製した。 [Examples 17 to 22]
As shown in Table 2, the reflective polarizers of Examples 1 to 16 are respectively a blue reflective layer (first light reflective layer), a green reflective layer (second light reflective layer), and a red reflective layer (third The optical elements of Examples 17 to 21 were formed by providing a reflective polarizer including a plurality of light reflective layers stacked as a light reflective layer, and further laminating a λ / 4 plate and a polarizer. In addition, an optical element of Example 22 including a reflective polarizer in which an infrared reflective layer (fourth light reflective layer) was further laminated on the configuration of Example 19 was produced.
　以下に第一から第三の光反射層の積層方法を説明する。
　第二の光反射層および第三の光反射層を、それぞれ上記仮支持体上に作製した。第二の光反射層上に市販のアクリル接着剤（東亞合成株式会社製ＵＶ－３３００）を塗布した。この塗布面を第一の光反射層に直接貼りあわせ、仮支持体側からメタルハライドランプを用いて、照射量１００ｍＪ／ｃｍ2の紫外線を照射して接着剤を硬化させた後、第二の光反射層から仮支持体を剥離した。さらにその上に第三の光反射層を、第二の光反射層と同様の手法で貼り合わせたが、仮支持体は剥離しなかった。得られた反射偏光子は、仮支持体上に第一の光反射層、接着剤層、第二の光反射層、接着剤層、第三の光反射層、仮支持体の順で積層されたものである。 A method for laminating the first to third light reflecting layers will be described below.
A second light reflecting layer and a third light reflecting layer were each formed on the temporary support. A commercially available acrylic adhesive (UV-3300 manufactured by Toagosei Co., Ltd.) was applied on the second light reflecting layer. The coated surface is directly bonded to the first light reflecting layer, and the adhesive is cured by irradiating ultraviolet rays with a dose of 100 mJ / cm 2 using a metal halide lamp from the temporary support side, and then the second light reflecting layer. The temporary support was peeled from the layer. Further, a third light reflecting layer was bonded thereon by the same method as that for the second light reflecting layer, but the temporary support was not peeled off. The obtained reflective polarizer is laminated on the temporary support in the order of the first light reflection layer, the adhesive layer, the second light reflection layer, the adhesive layer, the third light reflection layer, and the temporary support. It is a thing.
＜λ／４板の積層＞
　λ／４板として
セルロース支持体上に円盤状液晶化合物層を設けたフィルムを用いた。
＜λ／４板の作製＞
　まず、λ／４板のためのセルロースエステル支持体を作製した。 <Lamination of λ / 4 plate>
A film in which a discotic liquid crystal compound layer was provided on a cellulose support was used as a λ / 4 plate.
<Production of λ / 4 plate>
First, a cellulose ester support for a λ / 4 plate was prepared.
（セルロースエステル溶液Ａ－１の調製）
　下記の組成物をミキシングタンクに投入し、加熱しながら攪拌して、各成分を溶解し、セルロースエステル溶液Ａ－１を調製した。 (Preparation of cellulose ester solution A-1)
The following composition was put into a mixing tank and stirred while heating to dissolve each component to prepare a cellulose ester solution A-1.
セルロースエステル溶液Ａ－１の組成
・セルロースアセテート（アセチル化度２．８６）　　１００質量部
・メチレンクロライド　　　　　　　　　　　　　　　３２０質量部
・メタノール　　　　　　　　　　　　　　　　　　　　８３質量部
・１－ブタノール　　　　　　　　　　　　　　　　　　　３質量部
・トリフェニルフォスフェート　　　　　　　　　　　７．６質量部
・ビフェニルジフェニルフォスフェート　　　　　　　３．８質量部 Composition of Cellulose Ester Solution A-1 • Cellulose acetate (acetylation degree 2.86) 100 parts by mass • 320 parts by mass of methylene chloride • 83 parts by mass of methanol • 3 parts by mass of 1-butanol • 7.6 parts by mass of triphenyl phosphate・ 3.8 parts by mass of biphenyl diphenyl phosphate
（マット剤分散液Ｂ－１の調製）
　下記の組成物を分散機に投入し、攪拌して各成分を溶解し、マット剤分散液Ｂ－１を調製した。 (Preparation of matting agent dispersion B-1)
The following composition was charged into a disperser and stirred to dissolve each component to prepare a matting agent dispersion B-1.
マット剤分散液Ｂ－１の組成
　・シリカ粒子分散液（平均粒径１６ｎｍ）
　　"ＡＥＲＯＳＩＬ　Ｒ９７２"、日本アエロジル（株）製
　　　　　　　　　　　　　　　　　　　　　１０．０質量部
　・メチレンクロライド　　　　　　　　　　７２．８質量部
　・メタノール　　　　　　　　　　　　　　　３．９質量部
　・ブタノール　　　　　　　　　　　　　　　０．５質量部
　・セルロースエステル溶液Ａ－１　　　　　１０．３質量部 Composition of matting agent dispersion B-1 Silica particle dispersion (average particle size 16 nm)
"AEROSIL R972", manufactured by Nippon Aerosil Co., Ltd. 10.0 parts by mass-Methylene chloride 72.8 parts by mass-Methanol 3.9 parts by mass-Butanol 0.5 parts by mass-Cellulose ester solution A-1 10.3 parts by mass
　（紫外線吸収剤溶液Ｃ－１の調製）
　下記の組成物を別のミキシングタンクに投入し、加熱しながら攪拌して、各成分を溶解し、紫外線吸収剤溶液Ｃ－１を調製した。 (Preparation of UV absorber solution C-1)
The following composition was put into another mixing tank and stirred while heating to dissolve each component to prepare an ultraviolet absorber solution C-1.
紫外線吸収剤溶液Ｃ－１の組成
　・紫外線吸収剤（下記ＵＶ－１）　　　　　１０．０質量部
　・紫外線吸収剤（下記ＵＶ－２）　　　　　１０．０質量部
　・メチレンクロライド　　　　　　　　　　５５．７質量部
　・メタノール　　　　　　　　　　　　　　　　１０質量部
　・ブタノール　　　　　　　　　　　　　　　１．３質量部
　・セルロースエステル溶液Ａ－１　　　　　１２．９質量部 Composition of UV absorber solution C-1 UV absorber (UV-1 below) 10.0 parts by mass UV absorber (UV-2 below) 10.0 parts by mass Methylene chloride 55.7 parts by mass Methanol 10 Part by weight-1.3 parts by weight of butanol-12.9 parts by weight of cellulose ester solution A-1
Figure JPOXMLDOC01-appb-C000007
 
Figure JPOXMLDOC01-appb-C000007
 
（セルロースエステル支持体の作製）
　セルロースアシレート溶液Ａ－１を９４．６質量部、マット剤分散液Ｂ－１を１．３質量部とした混合物に、セルロースアシレート１００質量部当たり、紫外線吸収剤（ＵＶ－１）および紫外線吸収剤（ＵＶ－２）がそれぞれ１．０質量部となるように、紫外線吸収剤溶液Ｃ－１を加え、加熱しながら充分に攪拌して各成分を溶解し、ドープを調製した。得られたドープを３０℃に加温し、流延ギーサーを通して直径３ｍのドラムである鏡面ステンレス支持体上に流延した。支持体の表面温度は－５℃に設定し、塗布幅は１４７０ｍｍとした。流延したドープ膜をドラム上で３４℃の乾燥風を１５０ｍ3／分で当てることにより乾燥させ、残留溶剤が１５０％の状態でドラムより剥離した。剥離の際、搬送方向（長手方向）に１５％の延伸を行った。その後、フィルムの幅方向（流延方向に対して直交する方向）の両端をピンテンター（特開平４－１００９号公報の図３に記載のピンテンター）で把持しながら搬送し、幅手方向には延伸処理を行わなかった。さらに、熱処理装置のロール間を搬送することによりさらに乾燥し、セルロースアシレートフィルム（Ｔ１）を製造した。作製した長尺状のセルロースアシレートフィルム（Ｔ１）の残留溶剤量は０．２％で、厚みは８０μｍで、５５０ｎｍにおけるＲｅとＲｔｈはそれぞれ０．８ｎｍ、６４ｎｍであった。 (Production of cellulose ester support)
A mixture of 94.6 parts by mass of cellulose acylate solution A-1 and 1.3 parts by mass of matting agent dispersion B-1 was added to an ultraviolet absorber (UV-1) and an ultraviolet ray per 100 parts by mass of cellulose acylate. An ultraviolet absorbent solution C-1 was added so that the amount of the absorbent (UV-2) was 1.0 part by mass, and each component was dissolved by heating and stirring sufficiently to prepare a dope. The obtained dope was heated to 30 ° C., and cast on a mirror surface stainless steel support, which was a drum having a diameter of 3 m, through a casting Giuser. The surface temperature of the support was set to −5 ° C., and the coating width was 1470 mm. The cast dope film was dried on the drum by applying a drying air of 34 ° C. at 150 m 3 / min, and peeled off from the drum with a residual solvent of 150%. During peeling, 15% stretching was performed in the transport direction (longitudinal direction). Thereafter, the film is conveyed while being held by a pin tenter (pin tenter described in FIG. 3 of JP-A-4-1009) at both ends in the width direction (direction perpendicular to the casting direction) and stretched in the width direction. No processing was performed. Furthermore, it dried further by conveying between the rolls of a heat processing apparatus, and manufactured the cellulose acylate film (T1). The produced long cellulose acylate film (T1) had a residual solvent amount of 0.2%, a thickness of 80 μm, and Re and Rth at 550 nm of 0.8 nm and 64 nm, respectively.
＜λ／４層Ｆの形成＞
　配向層としてクラレ社製ポバールＰＶＡ－１０３を純水に溶解後に乾燥膜厚が０．５μｍになるように濃度調整した溶液を、上記で作製したセルロースアシレート上にバー塗布し、その後、１００℃で５分間加熱した。さらにこの表面をラビング処理して配向層を形成した。
　続いて下記の組成の溶質を、乾燥膜厚１μｍになるように濃度を調製してＭＥＫに溶解し、塗布液を調製した。この塗布液を上記の配向層上にバー塗布して、溶媒を８５℃、２分間保持して溶媒を気化させた後に１００℃で４分間加熱熟成を行って、均一な配向状態を得た。なお、円盤状化合物は支持体平面に対して垂直配向していた。
　その後この塗布膜を８０℃に保持し、これに窒素雰囲気下で高圧水銀灯を用いて紫外線照射してλ／４板を形成した。 <Formation of λ / 4 layer F>
As an alignment layer, a solution prepared by dissolving Kuraray's Poval PVA-103 in pure water and adjusting the concentration so that the dry film thickness becomes 0.5 μm was applied onto the cellulose acylate prepared above with a bar, and then 100 ° C. For 5 minutes. Further, this surface was rubbed to form an alignment layer.
Subsequently, a concentration of a solute having the following composition was adjusted to a dry film thickness of 1 μm and dissolved in MEK to prepare a coating solution. This coating solution was applied onto the alignment layer with a bar, and the solvent was kept at 85 ° C. for 2 minutes to evaporate the solvent, followed by heat aging at 100 ° C. for 4 minutes to obtain a uniform alignment state. The discotic compound was aligned perpendicular to the support plane.
Thereafter, this coating film was kept at 80 ° C. and irradiated with ultraviolet rays using a high pressure mercury lamp in a nitrogen atmosphere to form a λ / 4 plate.
＜λ/４層形成の塗布液の溶質組成＞
円盤状液晶化合物（化合物１）　　３５質量部
円盤状液晶化合物（化合物２）　　３５質量部
配向助剤（化合物３）　　　　　　　１質量部
配向助剤（化合物４）　　　　　　　１質量部
重合開始剤（化合物５）　　　　　　３質量部 <Solute composition of coating solution for forming λ / 4 layer>
Discotic liquid crystal compound (Compound 1) 35 parts by mass Discotic liquid crystal compound (Compound 2) 35 parts by mass alignment aid (Compound 3) 1 part by mass alignment aid (Compound 4) 1 part by mass polymerization initiator (Compound 5) 3 Parts by mass
Figure JPOXMLDOC01-appb-C000008
 
Figure JPOXMLDOC01-appb-C000008
 
Figure JPOXMLDOC01-appb-C000009
 
Figure JPOXMLDOC01-appb-C000009
 
Figure JPOXMLDOC01-appb-C000010
 
Figure JPOXMLDOC01-appb-C000010
 
Figure JPOXMLDOC01-appb-C000011
 
Figure JPOXMLDOC01-appb-C000011
 
Figure JPOXMLDOC01-appb-C000012
 
得られたλ/４板のＲｅ（５５０）＝１２５ｎｍ、Ｒｔｈ（５５０）＝１ｎｍであった。
　第一の光反射層側の仮支持体を剥離して、このλ／４板のセルロース支持体側を、上記光反射層と同様の手法で上記反射偏光子の第一の光反射層上に貼り合わせた後、第三の光反射層の仮支持体を剥離してλ／４板付き反射偏光子とした。
Figure JPOXMLDOC01-appb-C000012

Re (550) = 125 nm and Rth (550) = 1 nm of the obtained λ / 4 plate.
The temporary support on the first light reflection layer side is peeled off, and the cellulose support side of this λ / 4 plate is pasted on the first light reflection layer of the reflective polarizer in the same manner as the light reflection layer. After the alignment, the temporary support of the third light reflecting layer was peeled off to obtain a reflective polarizer with a λ / 4 plate.
　先に準備した偏光子の一方の側に上記で作製したλ／４板付き反射偏光子を、λ／４板が偏光子側になるように貼り合わせ、他方に偏光板保護フィルムとして市販のセルロースアシレート系フィルム「ＴＤ８０ＵＬ」（富士フイルム社製）を貼り合せて、光学素子を作製した。すなわち、実施例１７～２１の光学素子は、第三の光反射層、接着層、第二の光反射層、接着層、第一の光反射層、接着層、λ／４板、接着層、偏光子および偏光板保護フィルムの順に積層された積層構造体である。
　なお、実施例２２の光学素子は、第三の光反射層側にさらに接着層を介して赤外反射層（第四の光反射層）を備えた構成であり、第二、第三の光反射層の積層と同様の手法で作製した。 The reflective polarizer with the λ / 4 plate prepared above is bonded to one side of the polarizer prepared above so that the λ / 4 plate is on the polarizer side, and the other is a commercially available cellulose as a polarizing plate protective film. An acylate film “TD80UL” (manufactured by FUJIFILM Corporation) was bonded to produce an optical element. That is, the optical elements of Examples 17 to 21 include a third light reflecting layer, an adhesive layer, a second light reflecting layer, an adhesive layer, a first light reflecting layer, an adhesive layer, a λ / 4 plate, an adhesive layer, It is the laminated structure laminated | stacked in order of the polarizer and the polarizing plate protective film.
The optical element of Example 22 has a configuration in which an infrared reflective layer (fourth light reflective layer) is further provided on the third light reflective layer side via an adhesive layer, and the second and third light components are provided. It was produced by the same method as the lamination of the reflective layer.
［比較例１１～１４］
　比較例１～１０の反射偏光子を、表２に示すように、それぞれ、青色反射層（第一の光反射層）、緑色反射層（第二の光反射層）、赤色反射層（第三の光反射層）として、上記実施例１７～２１と同様に積層して比較例１１～１３の光学素子を作製した。また、実施例２２と同様にして、さらに赤外反射層（第四の光反射層）を備えた比較例１４作製した。 [Comparative Examples 11 to 14]
As shown in Table 2, the reflective polarizers of Comparative Examples 1 to 10 are respectively a blue reflective layer (first light reflective layer), a green reflective layer (second light reflective layer), and a red reflective layer (third The optical elements of Comparative Examples 11 to 13 were fabricated by laminating as the light reflecting layer) in the same manner as in Examples 17 to 21 above. Moreover, it carried out similarly to Example 22, and produced the comparative example 14 further provided with the infrared reflection layer (4th light reflection layer).
［評価］
＜面内レターデーション値Ｒｅの測定方法＞
　実施例１～１６および比較例１～１０の反射偏光子について、面内レターデーション値Ｒｅを以下の方法により測定した。
　反射偏光子を形成後、その反射偏光子を上記アクリル接着剤を用いて光反射層側をガラス板に貼り合わせ、仮支持体を剥離した後、Ａｘｏｓｃａｎのスペクトル測定により各光反射層の光学特性を測定した。そのうち「Ｔｒａｎｓｍｉｔｔａｎｃｅ」のスペクトルから反射中心波長を求めた。そして、得られた反射中心波長の＋８０ｎｍにおける「Ｌｉｎｅａｒ　Ｒｅｔａｒｄａｎｃｅ(ｎｍ)」の平均値を、Ｒｅとした。 [Evaluation]
<Measurement method of in-plane retardation value Re>
For the reflective polarizers of Examples 1 to 16 and Comparative Examples 1 to 10, the in-plane retardation value Re was measured by the following method.
After forming the reflective polarizer, the reflective polarizer is bonded to the glass plate with the acrylic adhesive and the temporary support is peeled off, and then the optical characteristics of each light reflective layer are measured by Axoscan spectrum measurement. Was measured. Of these, the reflection center wavelength was determined from the spectrum of “Transmittance”. The average value of “Linear Retention (nm)” at +80 nm of the obtained reflection center wavelength was defined as Re.
＜斜めＲｅｔ（５０°）の測定方法＞
　実施例１～１６および比較例１～１０の反射偏光子について、斜めＲｅｔ（５０°）を以下の方法により測定した。
　Ｒｅ測定時に得られた遅相軸を軸として、Ａｘｏｓｃａｎのステージを５０°傾けたこと以外はＲｅと同様にスペクトル測定を行い、光学特性を測定した。そのうち「Ｔｒａｎｓｍｉｔｔａｎｃｅ」のスペクトルから得られた反射中心波長の＋８０ｎｍにおける「Ｌｉｎｅａｒ　Ｒｅｔａｒｄａｎｃｅ（ｎｍ)」の平均値をＲｅｔ（５０°）とした。 <Measurement method of oblique Ret (50 °)>
For the reflective polarizers of Examples 1 to 16 and Comparative Examples 1 to 10, oblique Ret (50 °) was measured by the following method.
Using the slow axis obtained during Re measurement as an axis, spectrum measurement was performed in the same manner as Re except that the Axoscan stage was tilted by 50 °, and optical characteristics were measured. Among them, the average value of “Linear Retention (nm)” at +80 nm of the reflection center wavelength obtained from the spectrum of “Transmittance” was defined as Ret (50 °).
＜評価用のバックライト側偏光板の作製＞
　実施例１～１６および比較例１～１０の反射偏光子を用いて、以下のように評価用のバックライト側偏光板を作製した。先に準備した偏光子の両面に市販のセルロースアシレート系フィルム「ＴＤ８０ＵＬ」（富士フイルム社製）をそれぞれ貼り合わせて積層体を得た。この積層体の一面に実施例１～１６および比較例１～１０で得られた反射偏光子を上記アクリル接着剤で貼合し、仮支持体を剥離することで、評価用のバックライト側偏光板を得た。すなわち評価用のバックライト側偏光板は、実施例１～１６もしくは比較例１～１０の反射偏光子、セルロースアシレート系フィルム、偏光子、セルロースアシレート系フィルムの積層構造体である。 <Preparation of backlight side polarizing plate for evaluation>
Using the reflective polarizers of Examples 1 to 16 and Comparative Examples 1 to 10, backlight side polarizing plates for evaluation were produced as follows. A commercially available cellulose acylate film “TD80UL” (manufactured by FUJIFILM Corporation) was bonded to both surfaces of the polarizer prepared in advance to obtain a laminate. The reflective polarizer obtained in Examples 1 to 16 and Comparative Examples 1 to 10 was bonded to one surface of this laminate with the above acrylic adhesive, and the temporary support was peeled off. I got a plate. That is, the backlight-side polarizing plate for evaluation is a laminated structure of the reflective polarizer, the cellulose acylate film, the polarizer, and the cellulose acylate film of Examples 1 to 16 or Comparative Examples 1 to 10.
＜液晶表示装置の作製＞
　市販の液晶表示装置（パナソニック社製、商品名ＴＨ－Ｌ４２Ｄ２）を分解し、バックライト側偏光板を以下のように変更して評価用の液晶表示装置を組み立てた。
　実施例１～１６および比較例１～１０については、上述のようにして作製した評価用のバックライト側偏光板を、実施例もしくは比較例の反射偏光子がバックライト側となるように上記分解した液晶表示装置のセルに貼合して評価用の液晶表示装置を組み立てた。
　実施例１７～２２および比較例１１～１３については、各例で作製した光学素子を、その反射偏光子がバックライト側になるように上記分解した液晶表示装置のセルに貼合して評価用の液晶表示装置を組み立てた。 <Production of liquid crystal display device>
A commercially available liquid crystal display device (trade name TH-L42D2 manufactured by Panasonic Corporation) was disassembled and the backlight side polarizing plate was changed as follows to assemble a liquid crystal display device for evaluation.
For Examples 1 to 16 and Comparative Examples 1 to 10, the evaluation-use backlight side polarizing plate produced as described above was decomposed so that the reflective polarizer of Example or Comparative Example was on the backlight side. The liquid crystal display device for evaluation was assembled by bonding to the cell of the liquid crystal display device.
For Examples 17 to 22 and Comparative Examples 11 to 13, the optical elements produced in each example were bonded to the above-disassembled liquid crystal display cell so that the reflective polarizer was on the backlight side. A liquid crystal display device was assembled.
＜５０°周り色味変化Δｕ’ｖ’（５０°）の測定＞
　液晶表示装置の色味座標ｕ’ｖ’の測定には、測定機（ＥＺ－Ｃｏｎｔｒａｓｔ１６０Ｄ、ＥＬＤＩＭ社製）を用いた。測定角度を極角５０°方向に固定し、方位角を１５°刻みで３６０°回転させて色味座標ｕ’、ｖ’の値を測定し、最大と最小の差分をとった色味変化Δｕ’ｖ’（５０°）を算出した。その値を評価指標とし、以下の評価基準に基づいて評価した。 <Measurement of color change Δu′v ′ (50 °) around 50 °>
A measuring machine (EZ-Contrast 160D, manufactured by ELDIM) was used to measure the color coordinates u′v ′ of the liquid crystal display device. The measurement angle is fixed to the polar angle 50 ° direction, the azimuth angle is rotated 360 ° in increments of 15 °, the values of the color coordinates u ′, v ′ are measured, and the color change Δu taking the difference between the maximum and the minimum 'v' (50 °) was calculated. The value was used as an evaluation index and evaluated based on the following evaluation criteria.
（実施例１～１６および比較例１～１０の評価基準）
　実施例１～５、比較例５および比較例８の青色光を反射する反射偏光子を備えた液晶表示装置は、比較例１を基準（基準１－１）とした。
　実施例６～１０、比較例６および比較例９の緑色光を反射する反射偏光子を備えた液晶表示装置は、比較例２を基準（基準１－２）とした。
　実施例１１～１５、比較例７および比較例１０の赤色光を反射する反射偏光子を備えた液晶表示装置は、比較例３を基準（基準１－３）とした。
　実施例１６の赤外光を反射する反射偏光子を備えた液晶表示装置は、比較例４を基準（基準１－４）とした。
　実施例１～１６および比較例１～１０について、上記各基準に対して以下のように評価した。
　Ａ：基準として用いた液晶表示装置の斜め色味変化よりも４０％以上、良好である
　Ｂ：基準として用いた液晶表示装置の斜め色味変化よりも２５％以上、４０％未満、良好である
　Ｃ：基準として用いた液晶表示装置の斜め色味変化よりも１０％以上、２５％未満、良好である
　Ｄ：基準として用いた液晶表示装置の斜め色味変化と同等以下である (Evaluation criteria of Examples 1 to 16 and Comparative Examples 1 to 10)
In the liquid crystal display devices including the reflective polarizers that reflect blue light of Examples 1 to 5, Comparative Example 5 and Comparative Example 8, Comparative Example 1 was used as a reference (Reference 1-1).
The liquid crystal display devices including the reflective polarizers that reflect green light in Examples 6 to 10, Comparative Example 6 and Comparative Example 9 were based on Comparative Example 2 (reference 1-2).
In the liquid crystal display devices including the reflective polarizers that reflect red light in Examples 11 to 15, Comparative Example 7 and Comparative Example 10, Comparative Example 3 was used as a reference (Reference 1-3).
In the liquid crystal display device including the reflective polarizer that reflects infrared light of Example 16, Comparative Example 4 was used as a reference (Reference 1-4).
Examples 1 to 16 and Comparative Examples 1 to 10 were evaluated as follows with respect to the above criteria.
A: 40% or more better than the oblique color change of the liquid crystal display device used as the reference B: 25% or more, less than 40% better than the oblique color change of the liquid crystal display device used as the reference C: 10% or more and less than 25% better than the oblique color change of the liquid crystal display device used as a reference D: Less than or equal to the oblique color change of the liquid crystal display device used as a reference
（実施例１７～２２および比較例１１～１４の評価）
　実施例１７～２１および比較例１２、１３は、比較例１１を基準（基準２－１）とした。
　実施例２２は、比較例１４を基準（基準２－２）とした。
　実施例１７～２２および比較例１２、１３について、各基準に対して以下のように評価した。
　Ａ：基準の液晶表示装置の斜め色味変化よりも４０％以上、良好である
　Ｂ：基準の液晶表示装置の斜め色味変化よりも２５％以上、４０％未満、良好である
　Ｃ：基準の液晶表示装置の斜め色味変化よりも１０％以上、２５％未満、良好である
　Ｄ：基準の液晶表示装置の斜め色味変化と同等以下である (Evaluation of Examples 17 to 22 and Comparative Examples 11 to 14)
Examples 17 to 21 and Comparative Examples 12 and 13 were based on Comparative Example 11 (Criteria 2-1).
In Example 22, Comparative Example 14 was used as a reference (Reference 2-2).
Examples 17 to 22 and Comparative Examples 12 and 13 were evaluated as follows for each criterion.
A: 40% or more better than the oblique color change of the standard liquid crystal display device B: 25% or more, less than 40% better than the oblique color change of the standard liquid crystal display device C: standard 10% or more and less than 25% better than the oblique color change of the liquid crystal display device D: equivalent to or less than the oblique color change of the standard liquid crystal display device
＜斜め輝度の測定方法＞
　実施例１７～２２および比較例１１～１４の光学素子を用いた液晶表示装置の白表示時の正面輝度を、測定機（ＥＺ－Ｃｏｎｔｒａｓｔ１６０Ｄ、ＥＬＤＩＭ社製）を用いて測定した。その結果をもとに、以下の基準で評価した。なお、評価光源および反射偏光子の積層数を合わせるために、実施例１７～２１および比較例１２～１３は比較例１１を基準とし、実施例２２は比較例１５を基準とした。その結果をもとに、以下のように評価した。 <Measurement method of oblique luminance>
The front luminance at the time of white display of the liquid crystal display devices using the optical elements of Examples 17 to 22 and Comparative Examples 11 to 14 was measured using a measuring instrument (EZ-Contrast 160D, manufactured by ELDIM). Based on the results, evaluation was made according to the following criteria. In order to match the number of layers of the evaluation light source and the reflective polarizer, Examples 17 to 21 and Comparative Examples 12 to 13 were based on Comparative Example 11, and Example 22 was based on Comparative Example 15. Based on the results, evaluation was performed as follows.
　Ａ：基準の液晶表示装置の斜め輝度よりも４０％以上、良好である
　Ｂ：基準の液晶表示装置の斜め輝度よりも２５％以上、４０％未満、良好である
　Ｃ：基準の液晶表示装置の斜め輝度よりも１０％以上、２５％未満、良好である
　Ｄ：基準の液晶表示装置の斜め輝度と同等以下である A: 40% or more better than the oblique luminance of the reference liquid crystal display device B: More than 25%, less than 40% better than the oblique luminance of the reference liquid crystal display device C: of the reference liquid crystal display device 10% or more and less than 25%, which is better than the oblique brightness D: It is equal to or less than the oblique brightness of the standard liquid crystal display device
[実施例２３、２４]
　実施例１７と同様にして、実施例１～１６で形成した反射偏光子を、表３に示すように、それぞれ、青色反射層（第一の光反射層）、緑色反射層（第二の光反射層）、赤色反射層（第三の光反射層）として積層して複数層の光反射層を含む反射偏光子を形成し、さらにλ／４板と積層して実施例２３の光学素子を形成した。実施例２３において、赤色反射層とλ／４板との間にさらに赤外反射層（第四の光反射層）を備えた実施例２４の光学素子を形成した。 [Examples 23 and 24]
In the same manner as in Example 17, the reflective polarizers formed in Examples 1 to 16 were used as shown in Table 3 for the blue reflective layer (first light reflective layer) and the green reflective layer (second light, respectively). A reflective polarizer including a plurality of light reflection layers is formed by laminating as a reflection layer) and a red reflection layer (third light reflection layer), and further laminated with a λ / 4 plate to form the optical element of Example 23. Formed. In Example 23, the optical element of Example 24 was further provided with an infrared reflection layer (fourth light reflection layer) between the red reflection layer and the λ / 4 plate.
[比較例１５～１７]
　比較例１１と同様に、比較例１～１０の反射偏光子のうち、表３に示すように、それぞれ、青色反射層（第一の光反射層）、緑色反射層（第二の光反射層）、赤色反射層（第三の光反射層）として積層して複数層の光反射層を含む反射偏光子を形成し、さらにλ／４板と積層して比較例１５、１６の光学素子を形成した。さらに、比較例１５において、赤色反射層とλ／４板との間にさらに赤外反射層（第四の光反射層）を備えた比較例１７の光学素子を形成した。 [Comparative Examples 15 to 17]
As in Comparative Example 11, among the reflective polarizers of Comparative Examples 1 to 10, as shown in Table 3, a blue reflective layer (first light reflective layer) and a green reflective layer (second light reflective layer), respectively. ), Forming a reflective polarizer including a plurality of light reflecting layers by laminating as a red reflecting layer (third light reflecting layer), and further laminating with a λ / 4 plate to obtain the optical elements of Comparative Examples 15 and 16. Formed. Furthermore, in Comparative Example 15, the optical element of Comparative Example 17 was further provided with an infrared reflective layer (fourth light reflective layer) between the red reflective layer and the λ / 4 plate.
＜画像表示機能付きミラーの作製＞
　市販の液晶表示装置（パナソニック社製、商品名ＴＨ－Ｌ４２Ｄ２）の視認側表面に、実施例２３、２４および比較例１５、１６それぞれの光学素子をλ／４板が液晶表示装置側になり、かつλ／４板の遅相軸と液晶表示装置視認側偏光板の吸収軸とが４５度になるように貼合し、画像表示機能付きミラーとした。 <Production of mirror with image display function>
On the viewing side surface of a commercially available liquid crystal display device (trade name TH-L42D2 manufactured by Panasonic Corporation), each optical element of Examples 23 and 24 and Comparative Examples 15 and 16 has a λ / 4 plate on the liquid crystal display device side. In addition, bonding was performed so that the slow axis of the λ / 4 plate and the absorption axis of the polarizing plate on the viewing side of the liquid crystal display device were 45 degrees to obtain a mirror with an image display function.
＜５０°周り色味変化Δｕ’ｖ’（５０°）の測定＞
　色味座標ｕ’ｖ’の測定には、測定機（ＥＺ－Ｃｏｎｔｒａｓｔ１６０Ｄ、ＥＬＤＩＭ社製）を用いた。測定角度を極角５０°方向に固定し、方位角を１５°刻みで３６０°回転させて色味座標ｕ’、ｖ’の値を測定し、最大と最小の差分をとった色味変化Δｕ’ｖ’（５０°）を算出した。その値を評価指標とし、以下の評価基準に基づいて評価した。 <Measurement of color change Δu′v ′ (50 °) around 50 °>
A measuring machine (EZ-Contrast 160D, manufactured by ELDIM) was used for measuring the color coordinates u′v ′. The measurement angle is fixed to the polar angle 50 ° direction, the azimuth angle is rotated 360 ° in increments of 15 °, the values of the color coordinates u ′, v ′ are measured, and the color change Δu taking the difference between the maximum and the minimum 'v' (50 °) was calculated. The value was used as an evaluation index and evaluated based on the following evaluation criteria.
（実施例２３、２４および比較例１５～１７の評価）
　実施例２３および比較例１６は、比較例１５を基準（基準３－１）とし、実施例２４は、比較例１７を基準（基準３－２）として以下のように評価した。
　Ａ：基準の光学素子を備えた画像表示機能付きミラーの斜め色味変化よりも４０％以上、良好である
　Ｂ：基準の光学素子を備えた画像表示機能付きミラーの斜め色味変化よりも２５％以上、４０％未満、良好である
　Ｃ：基準の光学素子を備えた画像表示機能付きミラーの斜め色味変化よりも１０％以上、２５％未満、良好である
　Ｄ：基準の光学素子を備えた画像表示機能付きミラーの斜め色味変化と同等以下である (Evaluation of Examples 23 and 24 and Comparative Examples 15 to 17)
Example 23 and Comparative Example 16 were evaluated as follows using Comparative Example 15 as a reference (Criteria 3-1) and Example 24 using Comparative Example 17 as a reference (Criteria 3-2).
A: 40% or more better than the oblique color change of the mirror with the image display function provided with the reference optical element B: 25 better than the oblique color change of the mirror with the image display function provided with the reference optical element %: Less than 40%, good C: 10% or more, less than 25%, better than oblique color change of mirror with image display function equipped with reference optical element D: Provided with reference optical element Less than or equal to the oblique color change of the mirror with image display function
＜斜め輝度の測定方法＞
　実施例２３、２４および比較例１５～１７の光学素子を用いた画像表示機能付きミラーの斜め輝度として、測定機（ＥＺ－Ｃｏｎｔｒａｓｔ１６０Ｄ、ＥＬＤＩＭ社製）を用いて、測定角度を極角５０°方向に固定し、方位角を１５°刻みで３６０°回転させて測定した白表示時の斜め輝度を測定した。その結果をもとに、以下の基準で評価した。なお、評価光源を合わせるために、実施例２３および比較例１６は、比較例１５を基準（基準３－１）とし、実施例２４は、比較例１７を基準（基準３－２）として以下のように評価した。 <Measurement method of oblique luminance>
As the oblique luminance of the mirror with an image display function using the optical elements of Examples 23 and 24 and Comparative Examples 15 to 17, using a measuring machine (EZ-Contrast 160D, manufactured by ELDIM), the measurement angle is a polar angle of 50 ° direction. The oblique luminance at the time of white display measured by rotating the azimuth angle by 360 ° in increments of 15 ° was measured. Based on the results, evaluation was made according to the following criteria. In order to match the evaluation light source, Example 23 and Comparative Example 16 are based on Comparative Example 15 as a standard (Criteria 3-1), and Example 24 is based on Comparative Example 17 as a standard (Criteria 3-2). It was evaluated as follows.
　Ａ：基準の光学素子を備えた画像表示機能付きミラーの斜め輝度よりも４０％以上、良好である
　Ｂ：基準の光学素子を備えた画像表示機能付きミラーの斜め輝度よりも２５％以上、４０％未満、良好である
　Ｃ：基準の光学素子を備えた画像表示機能付きミラーの斜め輝度よりも１０％以上、２５％未満、良好である
　Ｄ：基準の光学素子を備えた画像表示機能付きミラーの斜め輝度と同等以下である A: 40% or more better than the oblique luminance of the mirror with the image display function provided with the reference optical element B: 25% more than the oblique luminance of the mirror with the image display function provided with the reference optical element, 40 Less than%, good C: 10% or more and less than 25% better than the oblique luminance of the mirror with image display function provided with the reference optical element D: Mirror with image display function provided with the reference optical element Less than or equal to the diagonal brightness of
Figure JPOXMLDOC01-appb-T000013
 
Figure JPOXMLDOC01-appb-T000013
 
Figure JPOXMLDOC01-appb-T000014
 
Figure JPOXMLDOC01-appb-T000014
 
Figure JPOXMLDOC01-appb-T000015
 
Figure JPOXMLDOC01-appb-T000015
 
　表１の実施例１～１６に示すように、本発明の光学素子は、単層であっても、Ｒｅが０ｎｍであり、斜めレターデーション値Ｒｅｔの絶対値｜Ｒｅｔ（５０°）｜が５０ｎｍ以下であり、斜め色味変化においては、全てＣ以上の評価を得ることができた。
　また、｜Ｒｅｔ｜が１０ｎｍ以下の場合が５０°周り色味変化量が最も小さいことがわかる。
　一方、比較例１～４の収縮を行わなかった場合は、Ｒｅは０ｎｍであったが、斜めＲｅｔ（５０°）の絶対値が５０ｎｍ以上であったため、５０°周り色味変化が劣ったと考えられる。
　また、比較例５～７の一軸収縮の場合は、斜めＲｅｔ（５０°）の絶対値｜Ｒｅｔ（５０°）｜は５０ｎｍ以下であったが、Ｒｅが大きいため、５０°周り色味変化が劣ったと考えられる。
　また、二軸延伸した比較例８～１０は、斜めＲｅｔ（５０°）の絶対値が本発明の範囲より大きく外れたため、５０°周り色味変化が劣ったと考えられる。 As shown in Examples 1 to 16 in Table 1, even if the optical element of the present invention is a single layer, Re is 0 nm and the absolute value | Ret (50 °) | of the oblique retardation value Ret is 50 nm. It was as follows, and in the oblique color change, all evaluations of C or higher could be obtained.
It can also be seen that the amount of change in color around 50 ° is the smallest when | Ret | is 10 nm or less.
On the other hand, when the shrinkage of Comparative Examples 1 to 4 was not performed, Re was 0 nm, but since the absolute value of the oblique Ret (50 °) was 50 nm or more, it was considered that the color change around 50 ° was inferior. It is done.
In the case of uniaxial contraction of Comparative Examples 5 to 7, the absolute value | Ret (50 °) | of the oblique Ret (50 °) was 50 nm or less, but since Re is large, the color change around 50 ° It is considered inferior.
In addition, in Comparative Examples 8 to 10 that were biaxially stretched, the absolute value of the oblique Ret (50 °) deviated greatly from the range of the present invention, and therefore it is considered that the color change around 50 ° was inferior.
　また、さらには、表２において、実施例１７～実施例２２に示すように、青色、緑色、赤色の３層を積層した反射偏光子では、斜め色味変化はＣ以上の評価を得ることができ、さらには、各色の斜め色味変化が小さいため、斜め輝度にも優れる結果となった。
　特に、実施例１９および実施例２２は、５０°周り色味変化量が小さい各層を積層しているため、斜め輝度が高いことがわかる。 Further, in Table 2, as shown in Examples 17 to 22, in the reflective polarizer in which three layers of blue, green, and red are laminated, the oblique color change can be evaluated as C or more. In addition, since the change in oblique color of each color is small, the result is excellent in oblique luminance.
In particular, Example 19 and Example 22 show that the oblique luminance is high because each layer having a small color change amount around 50 ° is laminated.
　表３に示すように、実施例２３、２４は比較例１７、１８に比べて斜め色味も、斜め輝度も良好という結果が得られ、本発明の光学素子は、画像表示機能付きミラーとして好適であることが明らかである。 As shown in Table 3, in Examples 23 and 24, as compared with Comparative Examples 17 and 18, the results that the oblique color and the oblique luminance are good are obtained, and the optical element of the present invention is suitable as a mirror with an image display function. It is clear that
　以上、実施例の評価から、仮支持体上に作製した反射偏光子を１０％～３０％収縮させることで色味変化が小さくなることが分かる。さらに、仮支持体上に作製した反射偏光子を１５％～２５％にすることで色味変化がさらに小さくなりより好ましい結果が得られることが分かる。 As described above, it can be seen from the evaluation of the examples that the color change is reduced by shrinking the reflective polarizer produced on the temporary support by 10% to 30%. Furthermore, it can be seen that by changing the reflective polarizer produced on the temporary support to 15% to 25%, the color change is further reduced and a more preferable result can be obtained.
[実施例２５]
＜二段階硬化＞
　実施例１の反射偏光子にメタルハライドランプを用いて５００ｍＪ／ｃｍ2紫外線照射
して、重合性液晶化合物をさらに硬化させて実施例２５の反射偏光子を作製した。
　実施例２５について、Ｒｅ、Ｒｅｔ（５０°）および５０°周りの色味変化を測定し、実施例１と比較した。実施例１と実施例２５についての各測定値は略同等であり、上記紫外線照射の前後で光学特性の変化は見られなかった。
　実施例１と実施例２５の射偏光子を６０℃９０％ＲＨの環境で５００時間経時させて評価した。 [Example 25]
<Two-stage curing>
The reflective polarizer of Example 1 was irradiated with 500 mJ / cm 2 ultraviolet rays using a metal halide lamp, and the polymerizable liquid crystal compound was further cured to produce the reflective polarizer of Example 25.
For Example 25, Re, Ret (50 °) and color change around 50 ° were measured and compared with Example 1. The measured values for Example 1 and Example 25 were substantially the same, and no change in optical characteristics was observed before and after the ultraviolet irradiation.
The reflective polarizers of Example 1 and Example 25 were evaluated after aging for 500 hours in an environment of 60 ° C. and 90% RH.
　実施例１のフィルムはＲｅｔ（５０°）が２０ｎｍ増加したのに対し、実施例２５のフィルムは１ｎｍ減少に留まり、Ｒｅｔ（５０°）の湿熱耐久性が向上していることを確認した。 The film of Example 1 increased Ret (50 °) by 20 nm, whereas the film of Example 25 remained reduced by 1 nm, and it was confirmed that the wet heat durability of Ret (50 °) was improved.
１　　　バックライト側偏光板
２　　　位相差フィルム
３　　　偏光子
４　　　偏光板保護フィルム
１１　　光学素子
１２　　λ／４板
１３　　反射偏光子
１４ａ　第一の光反射層
１４ｂ　第二の光反射層
１４ｃ　第三の光反射層
２０　　接着層（接着剤）
２１　　光学シート部材
３１　　バックライトユニット
４１　　薄層トランジスタ基板
４２　　液晶セル
４３　　カラーフィルター基板
４４　　表示側偏光板
５１、６０　　液晶表示装置 DESCRIPTION OF SYMBOLS 1 Backlight side polarizing plate 2 Retardation film 3 Polarizer 4 Polarizing plate protective film 11 Optical element 12 (lambda) / 4 board 13 Reflective polarizer 14a First light reflection layer 14b Second light reflection layer 14c Third light reflection Layer 20 Adhesive layer (adhesive)
21 Optical sheet member 31 Backlight unit 41 Thin layer transistor substrate 42 Liquid crystal cell 43 Color filter substrate 44 Display side polarizing plate 51, 60 Liquid crystal display device

Claims (6)

  1. 　棒状液晶化合物からなるコレステリック液晶相が固定化された光反射層を含む反射偏光子を備え、
    　前記反射偏光子は、反射中心波長の＋８０ｎｍにおいて、正面レターデーション値Ｒｅが０ｎｍ≦Ｒｅ＜１０ｎｍであり、かつ極角５０°方向のレターデーション値Ｒｅｔの絶対値｜Ｒｅｔ（５０°）｜が、｜Ｒｅｔ（５０°）｜≦５０ｎｍである光学素子。     A reflective polarizer including a light reflecting layer in which a cholesteric liquid crystal phase made of a rod-like liquid crystal compound is fixed,
    The reflection polarizer has a front retardation value Re of 0 nm ≦ Re <10 nm at a reflection center wavelength of +80 nm, and an absolute value | Ret (50 °) | of the retardation value Ret in the polar angle 50 ° direction is | Ret (50 °) | ≦ 50 nm.
  2. 　前記光反射層が、第一の光反射層、第二の光反射層および第三の光反射層を含んでなり、
    　前記第一の光反射層、前記第二の光反射層および前記第三の光反射層のうち、いずれか一つが反射中心波長３８０～４９９ｎｍかつ半値幅１００ｎｍ以下である反射率のピークを有する青色反射層であり、いずれか一つが反射中心波長５００～５９９ｎｍかつ半値幅２００ｎｍ以下である反射率のピークを有する緑色反射層であり、いずれか一つが反射中心波長６００～７５０ｎｍかつ半値幅１５０ｎｍ以下である反射率のピークを有する赤色反射層である請求項１記載の光学素子。     The light reflecting layer comprises a first light reflecting layer, a second light reflecting layer and a third light reflecting layer;
    Blue having a reflectance peak in which any one of the first light reflecting layer, the second light reflecting layer, and the third light reflecting layer has a reflection center wavelength of 380 to 499 nm and a half width of 100 nm or less. A reflective layer, any one of which is a green reflective layer having a reflectance peak with a reflection center wavelength of 500 to 599 nm and a half width of 200 nm or less, and any one of which has a reflection center wavelength of 600 to 750 nm and a half width of 150 nm or less. 2. The optical element according to claim 1, wherein the optical element is a red reflecting layer having a certain reflectance peak.
  3. 　前記反射偏光子の少なくとも一方の面にλ／４板を備える請求項１または２記載の光学素子。 The optical element according to claim 1 or 2, further comprising a λ / 4 plate on at least one surface of the reflective polarizer.
  4. 　棒状液晶化合物からなるコレステリック液晶相が固定化された反射偏光子を備えた光学素子の製造方法であって、
    　ポリマー主鎖がフィルム面内方向に配向している支持体上に棒状液晶化合物を含む重合性組成物から塗膜を形成する工程、
    　前記塗膜を硬化させる工程、および
    　前記硬化させた塗膜を前記支持体と一緒に二軸収縮する工程により前記反射偏光子を形成する光学素子の製造方法。     A method for producing an optical element comprising a reflective polarizer in which a cholesteric liquid crystal phase comprising a rod-like liquid crystal compound is fixed,
    Forming a coating film from a polymerizable composition containing a rod-like liquid crystal compound on a support having a polymer main chain oriented in the film in-plane direction;
    The manufacturing method of the optical element which forms the said reflective polarizer by the process of hardening the said coating film, and the process of biaxially shrinking the said cured coating film with the said support body.
  5. 　前記二軸収縮する工程が、前記支持体の４辺のうち各々の辺の収縮倍率が１５％以上２５％以下になるように収縮させる請求項４記載の製造方法。 The manufacturing method according to claim 4, wherein the biaxial shrinking step shrinks the shrinkage factor of each side of the four sides of the support so as to be 15% or more and 25% or less.
  6. 　少なくとも、請求項３記載の光学素子と、液晶セルと、バックライトユニットとを備える液晶表示装置。 A liquid crystal display device comprising at least the optical element according to claim 3, a liquid crystal cell, and a backlight unit.
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