WO2023238927A1 - 光学用積層体、積層光学フィルム、光学物品、仮想現実表示装置 - Google Patents

光学用積層体、積層光学フィルム、光学物品、仮想現実表示装置 Download PDF

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Publication number
WO2023238927A1
WO2023238927A1 PCT/JP2023/021523 JP2023021523W WO2023238927A1 WO 2023238927 A1 WO2023238927 A1 WO 2023238927A1 JP 2023021523 W JP2023021523 W JP 2023021523W WO 2023238927 A1 WO2023238927 A1 WO 2023238927A1
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layer
liquid crystal
light
film
crystal compound
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English (en)
French (fr)
Japanese (ja)
Inventor
竜二 実藤
洋平 ▲濱▼地
建太 宮原
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Fujifilm Corp
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Fujifilm Corp
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Priority to CN202380040278.9A priority Critical patent/CN119213338A/zh
Priority to JP2024527027A priority patent/JPWO2023238927A1/ja
Publication of WO2023238927A1 publication Critical patent/WO2023238927A1/ja
Priority to US18/958,112 priority patent/US20250085466A1/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
    • G02B5/3083—Birefringent or phase retarding elements
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
    • B32B7/02—Physical, chemical or physicochemical properties
    • B32B7/023—Optical properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B9/00—Layered products comprising a layer of a particular substance not covered by groups B32B11/00 - B32B29/00
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
    • G02B1/10—Optical coatings produced by application to, or surface treatment of, optical elements
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
    • G02B1/10—Optical coatings produced by application to, or surface treatment of, optical elements
    • G02B1/11—Anti-reflection coatings
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/02—Viewing or reading apparatus
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/08—Mirrors
    • 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
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements
    • G02B5/3016—Polarising elements involving passive liquid crystal elements
    • G—PHYSICS
    • G06—COMPUTING OR CALCULATING; COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
    • G06F3/01—Input arrangements or combined input and output arrangements for interaction between user and computer
    • G06F3/011—Arrangements for interaction with the human body, e.g. for user immersion in virtual reality

Definitions

  • the present invention relates to an optical laminate, a laminated optical film, an optical article, and a virtual reality display device.
  • a reflective polarizer is a polarizer that has the function of reflecting one polarized light of incident light and transmitting the other polarized light.
  • the light reflected by the reflective polarizer and the transmitted light have polarization states orthogonal to each other.
  • mutually orthogonal polarization states refer to polarization states that are located at antipodal points to each other on the Poincaré sphere.
  • mutually orthogonal linearly polarized light, or right-handed circularly polarized light and left-handed circularly polarized light This applies.
  • Reflective linear polarizers in which transmitted light and reflected light are linearly polarized light include, for example, a film obtained by stretching a dielectric multilayer film as described in Patent Document 1, and a wire grid as described in Patent Document 2. Polarizers are known.
  • a reflective circular polarizer in which transmitted light and reflected light become circularly polarized light for example, a film having a light reflective layer with a fixed cholesteric liquid crystal phase as described in Patent Document 3 is known.
  • a reflective polarizer is used for the purpose of extracting only specific polarized light from incident light or separating incident light into two polarized lights. For example, in a liquid crystal display device, by reflecting and reusing unnecessary polarized light from a backlight, it is used as a brightness-enhancing film that increases light utilization efficiency. In a liquid crystal projector, it is also used as a beam splitter that separates light from a light source into two linearly polarized lights and supplies each to a liquid crystal panel.
  • Patent Document 4 discloses a vehicle-mounted room mirror that reflects light from behind using a reflective polarizer.
  • Patent Document 5 describes a method of generating a virtual image by reflecting light between a reflective polarizer and a half mirror to make it go back and forth in order to make the display unit smaller and thinner in virtual reality display devices, electronic viewfinders, etc. is disclosed.
  • the present invention has been made in view of the above problems, and the problem to be solved by the present invention is to provide an optical reflective circular polarizer that can be used in a reflective circular polarizer that causes less ghosting when used in virtual reality display devices, electronic viewfinders, etc.
  • An object of the present invention is to provide a laminate for use in optical applications, a laminated optical film including the reflective circular polarizer, an optical article including the optical laminate, and a virtual reality display device including the optical article.
  • the first layer to the fourth layer are all cholesteric liquid crystal layers, All of the first layer to the fourth layer have light reflectivity,
  • the center wavelength of the reflected light of the first layer is within the range of 430 to 570 nm
  • the center wavelength of the reflected light of the second layer is within the range of 550 to 670 nm
  • the center wavelength of the reflected light of the third layer is within the range of 430 to 570 nm
  • the center wavelength of the reflected light of the fourth layer is within the range of 550 to 670 nm
  • the sign of the retardation in the thickness direction of the first layer at a wavelength of 550 nm and the sign of the retardation in the thickness direction at a wavelength of 550 nm of the second layer are opposite,
  • An optical laminate, wherein the sign of the retardation in the thickness direction at a wavelength of 550 nm of the third layer is opposite to the sign of the retardation
  • the center wavelength of the reflected light of the first layer is within the range of 430 to 480 nm
  • the center wavelength of the reflected light of the second layer is within the range of 600 to 670 nm
  • the center wavelength of the reflected light of the third layer is within the range of 520 to 570 nm
  • the center wavelength of the reflected light of the fourth layer is within the range of 550 to 620 nm
  • One of the first layer and the second layer is a cholesteric liquid crystal layer formed using a rod-like liquid crystal compound, and the other is a cholesteric liquid crystal layer formed using a discotic liquid crystal compound.
  • One of the third layer and the fourth layer is a cholesteric liquid crystal layer formed using a rod-like liquid crystal compound, and the other is a cholesteric liquid crystal layer formed using a discotic liquid crystal compound.
  • ⁇ 4> The optical laminate according to any one of ⁇ 1> to ⁇ 3>, wherein the difference in thickness of each layer from the first layer to the fourth layer is less than 0.5 ⁇ m.
  • a laminated optical film comprising at least a reflective circular polarizer, a retardation layer for converting circularly polarized light into linearly polarized light, and a linear polarizer in this order
  • a laminated optical film, wherein the reflective circular polarizer is the optical laminate according to any one of ⁇ 1> to ⁇ 4>.
  • the linear polarizer includes a light-absorbing anisotropic layer containing at least a liquid crystal compound and a dichroic substance.
  • ⁇ 8> The laminated optical film according to any one of ⁇ 5> to ⁇ 7>, further comprising an antireflection layer on the surface.
  • An optical article comprising the optical laminate according to any one of ⁇ 1> to ⁇ 4>.
  • ⁇ 12> A virtual reality display device comprising the optical article according to ⁇ 11>.
  • an optical laminate that can be used in a reflective circular polarizer that causes less ghosting when used in virtual reality display devices, electronic viewfinders, and the like. Further, according to the present invention, it is possible to provide a laminated optical film including the reflective circular polarizer, an optical article including the optical laminate, and a virtual reality display device including the optical article.
  • FIG. 1 is a schematic diagram showing an example of a first embodiment of an optical laminate of the present invention. This is an example of a virtual reality display device using the laminated optical film of the present invention. This is an example of a virtual reality display device using the laminated optical film of the present invention. 1 is a schematic diagram showing an example of a laminated optical film of the present invention.
  • a numerical range expressed using " ⁇ " means a range that includes the numerical values written before and after " ⁇ " as the lower limit value and upper limit value.
  • orthogonal does not strictly represent 90°, but 90° ⁇ 10°, preferably 90° ⁇ 5°.
  • parallel does not strictly represent 0°, but represents 0° ⁇ 10°, preferably 0° ⁇ 5°.
  • 45° does not strictly represent 45°, but represents 45° ⁇ 10°, preferably 45° ⁇ 5°.
  • the term “absorption axis” refers to the polarization direction in which the absorbance is maximum within the plane when linearly polarized light is incident.
  • the term “reflection axis” means the polarization direction in which the reflectance is maximum within the plane when linearly polarized light is incident.
  • the “transmission axis” means a direction perpendicular to the absorption axis or the reflection axis in the plane.
  • slow axis means the direction in which the refractive index is maximum within the plane.
  • phase difference means in-plane retardation, unless otherwise specified, and is expressed as Re( ⁇ ).
  • Re( ⁇ ) represents in-plane retardation at wavelength ⁇
  • wavelength ⁇ is 550 nm.
  • the retardation in the thickness direction at the wavelength ⁇ is described as Rth( ⁇ ) in this specification.
  • Rth( ⁇ ) the wavelength ⁇ is assumed to be 550 nm.
  • the optical laminate of the present invention includes the first embodiment.
  • a first embodiment of the optical laminate of the present invention will be described.
  • the optical laminate of the first embodiment of the present invention includes a first layer, a second layer, a third layer, and a fourth layer in this order,
  • the first layer to the fourth layer are all cholesteric liquid crystal layers, All of the first layer to the fourth layer have light reflectivity,
  • the center wavelength of the reflected light of the first layer is within the range of 430 to 570 nm
  • the center wavelength of the reflected light of the second layer is within the range of 550 to 670 nm
  • the center wavelength of the reflected light of the third layer is within the range of 430 to 570 nm
  • the center wavelength of the reflected light of the fourth layer is within the range of 550 to 670 nm
  • the sign of Rth of the first layer at a wavelength of 550 nm and the sign of Rth of the second layer at a wavelength of 550 nm are opposite,
  • FIG. 1 is a schematic cross-sectional view showing an example of the configuration of an optical laminate 12 according to the first embodiment.
  • the optical laminate 12 includes a first layer 31, a second layer 32, a third layer 33, and a fourth layer 34, which are laminated in this order. Meets the above requirements. Note that the sign of Rth of the first layer 31 and the sign of Rth of the second layer 32 are opposite, and the sign of Rth of the third layer 33 and the sign of Rth of the fourth layer 34 are opposite. is the opposite.
  • the optical laminate of the first embodiment of the present invention can be used in a reflective circular polarizer.
  • the optical laminate of the first embodiment of the present invention includes a first layer, a second layer, a third layer, and a fourth layer in this order.
  • the first to fourth layers are cholesteric liquid crystal layers having light reflection properties.
  • the above-mentioned cholesteric liquid crystal layer refers to a layer formed by making a liquid crystal compound into a cholesteric liquid crystal phase and fixing the cholesteric liquid crystal phase.
  • a known cholesteric liquid crystal layer can be used, and for example, one described in JP 2020-060627A and the like can be used.
  • the cholesteric liquid crystal layer is preferably a cholesteric liquid crystal layer formed using a rod-like liquid crystal compound or a cholesteric liquid crystal layer formed using a discotic liquid crystal compound.
  • Rth tends to take a positive value
  • Rth tends to take a negative value.
  • the cholesteric liquid crystal layer formed using a rod-like liquid crystal compound is a cholesteric liquid crystal layer formed using a first liquid crystal compound that is substantially made of a rod-like liquid crystal compound, and is substantially made of a rod-like liquid crystal compound.
  • a cholesteric liquid crystal layer formed using a first liquid crystal compound consisting of a substantially rod-like liquid crystal compound refers to a layer formed by making the first liquid crystal compound into a cholesteric liquid crystal phase and fixing the alignment state of the cholesteric liquid crystal phase. Refers to layers.
  • substantially consisting of a rod-like liquid crystal compound means that the rod-like liquid crystal compound accounts for 95% by mass or more of the liquid crystal compound (first liquid crystal compound) contained in the cholesteric liquid crystal layer formed using the rod-like liquid crystal compound.
  • the first liquid crystal compound consisting essentially of a rod-like liquid crystal compound means that the content of the rod-like liquid crystal compound is 95% by mass or more based on the total mass of the first liquid crystal compound.
  • the first liquid crystal compound consists only of rod-like liquid crystal compounds.
  • the cholesteric liquid crystal layer formed using a discotic liquid crystal compound is a cholesteric liquid crystal layer formed using a second liquid crystal compound that is substantially made of a discotic liquid crystal compound, and is a cholesteric liquid crystal layer formed using a second liquid crystal compound that is substantially made of a discotic liquid crystal compound.
  • a cholesteric liquid crystal layer formed using a second liquid crystal compound consisting essentially of a disk-shaped liquid crystal compound refers to a layer formed by using a second liquid crystal compound having a cholesteric liquid crystal phase and fixing the alignment state of the cholesteric liquid crystal phase.
  • the second liquid crystal compound substantially consisting of a discotic liquid crystal compound means that the content of the discotic liquid crystal compound is 95% by mass or more based on the total mass of the second liquid crystal compound. .
  • the second liquid crystal compound consists of only a discotic liquid crystal compound.
  • the rod-like liquid crystal compound included in the cholesteric liquid crystal layer formed using the rod-like liquid crystal compound is not particularly limited, and any known rod-like liquid crystal compound can be used.
  • the cholesteric liquid crystal layer formed using a rod-like liquid crystal compound may be a layer in which the orientation of the rod-like liquid crystal compound that is in the cholesteric liquid crystal phase is maintained, and typically, a cholesteric liquid crystal layer formed using a polymerizable liquid crystal layer having a polymerizable group is used. It can be formed by aligning a rod-like liquid crystal compound into a cholesteric liquid crystal phase by adding a chiral agent or the like, and then polymerizing and hardening it by ultraviolet irradiation, heating, etc.
  • the cholesteric liquid crystal layer formed using the rod-like liquid crystal compound formed as described above may be a layer that has been changed to a state in which the orientation form does not change due to an external field, external force, or the like.
  • the rod-like liquid crystal compound may no longer exhibit liquid crystallinity.
  • the polymerizable rod-like liquid crystal compound may have a high molecular weight due to a curing reaction and may no longer have liquid crystallinity.
  • the pitch of the cholesteric liquid crystal phase changes depending on the type of chiral agent used together with the polymerizable rod-like liquid crystal compound and its concentration, and by adjusting any one or more of the above, a cholesteric liquid crystal phase with a desired pitch can be obtained.
  • the direction of spiral rotation and the method for measuring the pitch are described in "Introduction to Liquid Crystal Chemistry Experiments,” edited by the Japan Liquid Crystal Society, published by Sigma Publishing, 2007, p. 46, and "Liquid Crystal Handbook,” Liquid Crystal Handbook Editorial Committee, Maruzen, p. 196. A method can be used.
  • the discotic liquid crystal compound included in the cholesteric liquid crystal layer formed using the discotic liquid crystal compound is not particularly limited, and any known discotic liquid crystal compound can be used.
  • the cholesteric liquid crystal layer formed using a discotic liquid crystal compound may be a layer in which the orientation of the discotic liquid crystal compound that is in the cholesteric liquid crystal phase is maintained, and typically, the cholesteric liquid crystal layer does not contain a polymerizable group.
  • a polymerizable discotic liquid crystal compound is oriented in a cholesteric liquid crystal phase by adding a chiral agent, etc., and then polymerized and hardened by ultraviolet irradiation, heating, etc. to form a layer with no fluidity. can.
  • the cholesteric liquid crystal layer formed using the discotic liquid crystal compound formed as described above may be a layer that has been changed to a state in which the alignment form does not change due to an external field, external force, or the like.
  • the discotic liquid crystal compound in the layer may no longer exhibit liquid crystallinity.
  • the polymerizable discotic liquid crystal compound may have a high molecular weight due to a curing reaction and may no longer have liquid crystallinity.
  • the center wavelength ⁇ of the reflected light of a cholesteric liquid crystal layer formed using a discotic liquid crystal compound depends on the pitch of the helical structure in the cholesteric liquid crystal phase, and is the same as in the case of a cholesteric liquid crystal layer formed using a rod-like liquid crystal compound. can be defined and measured in a similar way.
  • the pitch of the cholesteric liquid crystal phase changes depending on the type of chiral agent used together with the polymerizable discotic liquid crystal compound and its concentration, and by adjusting any one or more of the above, a cholesteric liquid crystal phase with a desired pitch can be obtained.
  • the above-mentioned literature can be referred to for the direction of spiral rotation and the method for measuring the pitch.
  • the center wavelength of the reflected light of the first layer is within the range of 430 to 570 nm
  • the center wavelength of the reflected light of the second layer is within the range of 550 to 670 nm
  • the center wavelength of the reflected light of the third layer is within the range of 430 to 570 nm
  • the center wavelength of the reflected light of the fourth layer is within the range of 550 to 670 nm.
  • the center wavelengths of the reflected light from the first layer and the third layer are preferably in the range of 430 to 480 nm and 520 to 570 nm, respectively. Furthermore, the center wavelengths of the reflected light from the second layer and the fourth layer are preferably in the range of 550 to 620 nm and 600 to 670 nm, respectively. It is also preferable that the center wavelengths of the reflected lights of the first layer to the fourth layer are different from each other.
  • the center wavelengths of the reflected light of the first layer and the third layer are within the range of 430 to 480 nm for one, and within the range of 520 to 570 nm for the other. Furthermore, it is more preferable that the center wavelengths of the reflected light from the second layer and the fourth layer are within the range of 550 to 620 nm for one and 600 to 670 nm for the other.
  • the layer may correspond to a blue light reflective layer. In this case, the reflectance at the center wavelength of the reflected light is preferably 40% or more and less than 50%. If the center wavelength of the reflected light is 520 to 570 nm, the layer may correspond to a green light reflective layer. In this case, the reflectance at the center wavelength of the reflected light is preferably 40% or more and less than 50%. If the center wavelength of the reflected light is 550 to 620 nm, the layer may correspond to a yellow light reflective layer. In this case, the reflectance at the center wavelength of the reflected light is preferably 40% or more and less than 50%.
  • the layer may correspond to a red light reflective layer.
  • the reflectance at the center wavelength of the reflected light is preferably 40% or more and less than 50%.
  • the above reflectance refers to the value when unpolarized light is incident.
  • the reflectance of the optical laminate was measured under the following conditions. An automatic absolute reflectance measurement system consisting of an ultraviolet-visible near-infrared spectrophotometer V-750 manufactured by JASCO Corporation is used. S-wave and P-wave polarized light with a wavelength of 350 to 900 nm is incident on the optical laminate at an incident angle of 5°.
  • a reflection spectrum is obtained by measuring the absolute reflectance for each of the S wave and P wave and calculating the average value for each wavelength. From the obtained reflectance spectrum, the average reflectance for light with a wavelength of 400 to 700 nm is calculated, and is taken as the reflectance of the optical laminate for light with a wavelength of 400 to 700 nm.
  • the center wavelength of the reflected light of the first layer is within the range of 430 to 480 nm
  • the center wavelength of the reflected light of the second layer is within the range of 600 to 670 nm
  • the center wavelength of the reflected light of the third layer is within the range of 430 to 480 nm. It is more preferable that the center wavelength is within the range of 520 to 570 nm
  • the center wavelength of the reflected light of the fourth layer is within the range of 550 to 620 nm.
  • ghosts can be further suppressed by arranging light reflecting layers in which the center wavelength of each reflected light is within the above range in the above order.
  • the sign of Rth at a wavelength of 550 nm of the first layer and the sign of Rth at a wavelength of 550 nm of the second layer are opposite, and the sign of Rth at a wavelength of 550 nm of the third layer is opposite.
  • the sign of Rth at 550 nm and the sign of Rth at the wavelength of 550 nm of the fourth layer are opposite.
  • the method of reversing the sign of Rth between the first layer and the second layer as described above is not particularly limited, as an aspect of establishing such a relationship of Rth, for example, An embodiment may be mentioned in which one of the layers is a cholesteric liquid crystal layer formed using a rod-like liquid crystal compound, and the other is a cholesteric liquid crystal layer formed using a discotic liquid crystal compound.
  • the method of reversing the sign of Rth between the third layer and the fourth layer as described above is not particularly limited, but as an aspect of establishing such a relationship of Rth, for example, An embodiment in which one of the fourth layers is a cholesteric liquid crystal layer formed using a rod-like liquid crystal compound and the other is a cholesteric liquid crystal layer formed using a discotic liquid crystal compound is mentioned. Further, it is also preferable that the sign of Rth is opposite between the second layer and the third layer.
  • the first layer and the third layer are cholesteric liquid crystal layers formed using a rod-shaped liquid crystal compound, and the second layer and the fourth layer are disc-shaped.
  • the cholesteric liquid crystal layer is formed using a liquid crystal compound
  • the first layer and the third layer are cholesteric liquid crystal layers formed using a discotic liquid crystal compound
  • the second layer and the fourth layer are cholesteric liquid crystal layers formed using a discotic liquid crystal compound.
  • the layer is a cholesteric liquid crystal layer formed using a rod-like liquid crystal compound.
  • the Rth of the cholesteric liquid crystal layer formed using a rod-like liquid crystal compound is preferably 8 to 800 nm, more preferably 16 to 560 nm, and even more preferably 24 to 400 nm at a wavelength of 550 nm.
  • the Rth of a cholesteric liquid crystal layer formed using a rod-like liquid crystal compound may be measured by taking out only the cholesteric liquid crystal layer formed using a rod-like liquid crystal compound from an optical laminate, or by measuring the Rth of a cholesteric liquid crystal layer formed using a rod-like liquid crystal compound. You may measure Rth of a layer produced under the same conditions as when producing a cholesteric liquid crystal layer formed using the above method.
  • the Rth of the cholesteric liquid crystal layer formed using a discotic liquid crystal compound is preferably -8 to -800 nm, more preferably -16 to -560 nm, and even more preferably -24 to -400 nm at a wavelength of 550 nm.
  • the Rth of the cholesteric liquid crystal layer formed using the discotic liquid crystal compound may be measured by taking out only the cholesteric liquid crystal layer formed using the discotic liquid crystal compound from the optical laminate, or by measuring the Rth of the cholesteric liquid crystal layer formed using the discotic liquid crystal compound. You may measure Rth of a layer produced under the same conditions as when producing a cholesteric liquid crystal layer formed using a liquid crystal compound.
  • the thickness of the first layer to the fourth layer is preferably 0.1 ⁇ m or more, more preferably 0.2 ⁇ m or more, and even more preferably 0.3 ⁇ m or more.
  • the thickness of the first layer to the fourth layer is preferably 10.0 ⁇ m or less, more preferably 7.0 ⁇ m or less, and even more preferably 5.0 ⁇ m or less, from the standpoint of further suppressing ghosts. Further, from the viewpoint of further suppressing ghosts, the difference in thickness between the first layer to the fourth layer is preferably less than 0.5 ⁇ m, and more preferably less than 0.3 ⁇ m.
  • the thickness of each layer from the first layer to the fourth layer can be measured by preparing a cross section of the optical laminate and observing it with a scanning electron microscope.
  • the thickness of each layer is a value obtained by averaging the thickness of each layer at five arbitrary points in the cross section of the optical laminate. Note that when the cross section of the optical laminate is observed with a scanning electron microscope, the regions of each layer from the first layer to the fourth layer can be distinguished by the difference in contrast of the photographed images. In addition, each layer from the first layer to the fourth layer can be distinguished by using composition analysis in the film thickness direction using time-of-flight secondary ion mass spectrometry (TOF-SIMS). I can do it.
  • TOF-SIMS time-of-flight secondary ion mass spectrometry
  • the thicknesses of the first to fourth layers can also be measured by preparing a cross section of the optical laminate and observing it with a transmission electron microscope.
  • the sign of Rth of the first layer and the sign of Rth of the second layer are opposite, and the sign of Rth of the third layer is opposite to the sign of Rth of the second layer. Since the signs of the Rth of the fourth layer are opposite, the Rth of the first layer and the Rth of the second layer cancel each other out, and the Rth of the third layer and the Rth of the fourth layer cancel each other out. Although it was mentioned above that the Rths cancel each other out, the details will be explained below.
  • each layer from reflective layer L1 to reflective layer Li (i is an integer of 4 or less)
  • Rth SRthi
  • the absolute value of all these SRthi (SRth1 to SRth4) is preferably 0.3 ⁇ m or less, more preferably 0.2 ⁇ m or less, and even more preferably 0.1 ⁇ m or less.
  • Rthi of each layer in the above formula is determined by the formula for calculating Rth described above. Note that in the first embodiment, n is read as 4. It is considered that by setting SRthi within the above-mentioned preferable range, it is possible to reduce the phase difference that occurs when passing through each reflective layer, and to further suppress the occurrence of ghosts even with respect to incident light from an oblique direction.
  • the first to fourth layers may be laminated in direct contact with each other, or may be laminated with another layer in between.
  • Other layers include, but are not particularly limited to, adhesion layers (for example, adhesive layers, pressure-sensitive adhesive layers, etc.), refractive index adjustment layers, resin films, positive C plates, alignment layers, and the like. Among these, it is preferable that the first to fourth layers are laminated in direct contact with each other.
  • a liquid crystal compound ( It is preferable that the alignment direction (slow axis direction) of the rod-shaped liquid crystal compound or discotic liquid crystal compound changes continuously at the interface.
  • a second cholesteric liquid crystal layer formed using a rod-shaped liquid crystal compound is formed on a first layer, which is a cholesteric liquid crystal layer formed using a discotic liquid crystal compound.
  • a coating solution containing a rod-like liquid crystal compound is applied directly onto the first layer, and the slow axis direction is made continuous at the interface by the alignment regulating force of the disk-like liquid crystal compound contained in the first layer. It can also be oriented.
  • the thickness of the optical laminate according to the first embodiment of the present invention is preferably 30 ⁇ m or less, more preferably 15 ⁇ m or less.
  • the lower limit is not particularly limited, but may be, for example, 1 ⁇ m or more, preferably 5 ⁇ m or more.
  • optical laminate (first embodiment) of the present invention can be manufactured by a known method, and the method is not particularly limited.
  • a composition containing a rod-like liquid crystal compound is applied onto a base material to form a cholesteric liquid crystal phase, and then the orientation state of the cholesteric liquid crystal phase is fixed.
  • a first cholesteric liquid crystal layer is formed, a composition containing a discotic liquid crystal compound is applied onto the first cholesteric liquid crystal layer to form a cholesteric liquid crystal phase, and the alignment state of the cholesteric liquid crystal phase is fixed to form a second cholesteric liquid crystal layer.
  • a liquid crystal layer is formed, a third cholesteric liquid crystal layer is formed on the second cholesteric liquid crystal layer in the same manner as the first cholesteric liquid crystal layer, and a third cholesteric liquid crystal layer is formed in the same manner as the second cholesteric liquid crystal layer.
  • One example is a method of forming a fourth cholesteric liquid crystal layer thereon.
  • the optical laminate of the present invention when used as a reflective circular polarizer and the reflective circular polarizer is stretched or molded, the reflection wavelength range as a reflective circular polarizer shifts to the shorter wavelength side. Therefore, it is preferable to manufacture an optical laminate assuming a wavelength shift in the reflection wavelength range in advance.
  • the optical laminate including a layer with a fixed cholesteric liquid crystal phase as a reflective circular polarizer when using an optical laminate including a layer with a fixed cholesteric liquid crystal phase as a reflective circular polarizer, the optical laminate is stretched by stretching or molding, and the helical pitch of the cholesteric liquid crystal phase becomes small. Therefore, it is advisable to set the helical pitch of the cholesteric liquid crystal phase large in advance.
  • the optical laminate preferably has an infrared light reflective layer having a reflectance of 40% or more at a wavelength of 800 nm.
  • an appropriate reflection wavelength range is selected at each location within the plane of the optical laminate according to the wavelength shift caused by stretching, and the optical laminate is may be manufactured. That is, within the plane of the optical laminate, there may be regions with different reflection wavelength ranges.
  • a method of forming a cholesteric liquid crystal layer by directly coating the above composition on each cholesteric liquid crystal layer was shown, but it is also possible to form a cholesteric liquid crystal layer by coating each cholesteric liquid crystal layer on a separate base material, and form an adhesive layer (e.g. A cholesteric liquid crystal layer may be laminated via an adhesive layer, an adhesive layer, or an adhesive layer.
  • any commercially available adhesive can be used as the adhesive used in the adhesive layer, but from the viewpoint of thinning and reducing the surface roughness Ra, it is preferable that the thickness is 25 ⁇ m or less. , more preferably 15 ⁇ m or less, and most preferably 6 ⁇ m or less. Moreover, it is preferable that the adhesive is one that does not easily generate outgas. In particular, when stretching or molding is performed, a vacuum process and/or heating process may be performed, but it is preferable that no outgassing occurs even under these conditions.
  • any commercially available adhesive can be used. For example, an epoxy resin adhesive and an acrylic resin adhesive can be used.
  • the thickness of the adhesive is preferably 25 ⁇ m or less, more preferably 5 ⁇ m or less, from the viewpoint of thinning and reducing the surface roughness Ra of a reflective circular polarizer using an optical laminate. , most preferably 1 ⁇ m or less.
  • the adhesive preferably has a viscosity of 300 cP or less, more preferably 100 cP or less, from the viewpoint of thinning the adhesive layer and applying the adhesive to an adherend with a uniform thickness.
  • the pressure-sensitive adhesive and the adhesive should be used on the surface of the layer to be adhered from the viewpoint of reducing the surface roughness Ra of the reflective circular polarizer using the optical laminate.
  • Appropriate viscoelasticity or thickness can also be selected to embed irregularities. From the viewpoint of embedding surface irregularities, it is preferable that the adhesive and the adhesive have a viscosity of 50 cP or more. Further, the thickness is preferably thicker than the height of the surface irregularities. Examples of methods for adjusting the viscosity of the adhesive include a method using an adhesive containing a solvent. In this case, the viscosity of the adhesive can be adjusted by adjusting the ratio of solvents. Furthermore, by drying the solvent after applying the adhesive to the adherend, the thickness of the adhesive can be further reduced.
  • the adhesive or adhesive used to bond each layer should be It is preferable that the refractive index difference between the two is small. Because the cholesteric liquid crystal layer has birefringence, the refractive index in the fast axis direction and the slow axis direction are different. Therefore, the value obtained by adding the refractive index in the fast axis direction and the slow axis direction and dividing by 2 is the liquid crystal layer.
  • the difference between the refractive index of the adjacent adhesive layer or adhesive layer is preferably 0.075 or less, more preferably 0.05 or less, and 0.025 or less. More preferred.
  • the refractive index of the pressure-sensitive adhesive or adhesive can be adjusted, for example, by mixing fine particles such as titanium oxide fine particles and zirconia fine particles.
  • the adhesive layer between each layer has a thickness of 100 nm or less.
  • the thickness of the adhesive layer is more preferably 50 nm or less, and even more preferably 30 nm or less.
  • An example of a method for forming an adhesive layer having a thickness of 100 nm or less is a method of vapor-depositing a ceramic adhesive such as silicon oxide (SiOx layer) on the bonding surface.
  • the bonding surface of the bonding member can be subjected to surface modification treatment such as plasma treatment, corona treatment, saponification treatment, etc.
  • an adhesive layer having a thickness of 100 nm or less can be provided by following the steps (1) to (3) below.
  • (1) Layers to be laminated are bonded to a temporary support made of a glass base material.
  • the vapor deposition can be performed using SiOx powder as a vapor deposition source, for example, using a vapor deposition apparatus manufactured by ULVAC (model number ULEYES). Further, it is preferable to perform plasma treatment on the surface of the formed SiOx layer. (3) After bonding the formed SiOx layers together, the temporary support is peeled off. It is preferable that the lamination is carried out at a temperature of, for example, 120°C.
  • the coating, adhesion, or lamination of each layer may be performed by a roll-to-roll method or by a sheet-wafer method.
  • the roll-to-roll method is preferable from the viewpoint of improving productivity and reducing axis misalignment of each layer.
  • the single-wafer method is preferable because it is suitable for small-volume, high-mix production, and because it allows selection of a special adhesive method such as the above-mentioned adhesive layer having a thickness of 100 nm or less.
  • methods for applying the adhesive to the adherend include, for example, a roll coating method, a gravure printing method, a spin coating method, a wire bar coating method, an extrusion coating method, a direct gravure coating method, a reverse gravure coating method, and a die coating method.
  • Known methods include a method, a spray method, and an inkjet method.
  • a reflective circular polarizer using the optical laminate of the present invention may include a support, an alignment layer, etc., but the support and alignment layer are peeled off when producing the laminated optical film described below. It may also be a temporary support that is removed. When using a temporary support, the thickness of the laminated optical film can be reduced by transferring the reflective circular polarizer to another laminate and then peeling and removing the temporary support. This phase difference is preferable because it can eliminate an adverse effect on the degree of polarization of transmitted light.
  • the type of support is not particularly limited, but it is preferably transparent to visible light, such as cellulose acylate, polycarbonate, polysulfone, polyethersulfone, polyacrylate and polymethacrylate, cyclic polyolefin, polyolefin, polyamide, polystyrene. , and polyester films can be used.
  • cellulose acylate film, cyclic polyolefin, polyacrylate, or polymethacrylate is preferred.
  • a support with high tear strength is preferred from the viewpoint of preventing breakage during peeling.
  • the support preferably has a small retardation from the viewpoint of suppressing an adverse effect on the degree of polarization of transmitted light.
  • the magnitude of Re at 550 nm is preferably 10 nm or less
  • the absolute value of Rth is preferably 50 nm or less.
  • the temporary support is used for quality inspection of reflective circular polarizers and other laminates. It is preferable that the phase difference is small.
  • the reflective circular polarizer using the optical laminate used in the laminated optical film is preferably transparent to near-infrared light.
  • the laminated optical film of the present invention includes at least a reflective circular polarizer, a retardation layer that converts circularly polarized light into linearly polarized light, and a linear polarizer in this order.
  • a reflective circular polarizer the optical laminate described above (first embodiment) is used.
  • Preferred embodiments of the optical laminate (first embodiment) are as described above.
  • a virtual reality display device using the laminated optical film of the present invention will be taken up, and the action of the laminated optical film of the present invention will be explained in detail. .
  • FIG. 2 is a schematic diagram of a virtual reality display device using the laminated optical film of the present invention.
  • a laminated optical film 100 having a reflective circular polarizer using the optical laminate described above, a half mirror 300, a circularly polarizing plate 400, and an image display.
  • a panel 500 is arranged.
  • a light beam 1000 emitted from the image display panel 500 passes through the circularly polarizing plate 400, becomes circularly polarized light, and passes through the half mirror 300.
  • the light ray 1000 is reflected by the half mirror, so that the light ray 1000 becomes circularly polarized light whose rotation direction is opposite to that of the circularly polarized light when it first enters the laminated optical film 100. Therefore, the light ray 1000 passes through the laminated optical film 100 and is visible to the user.
  • the image displayed on the image display panel 500 is enlarged because the half mirror has a concave mirror shape, and the user visually recognizes the enlarged virtual image. be able to.
  • FIG. 3 is a schematic diagram for explaining a case where a ghost occurs in the virtual reality display device shown in FIG. 2. More specifically, it is a schematic diagram illustrating a case where, in a virtual reality display device, when a light ray 2000 first enters the laminated optical film 100, it is transmitted without being reflected and becomes leaked light. As shown in FIG. 3, when the light ray 2000 is incident on the laminated optical film 100 for the first time, it is transmitted without being reflected and leakage light occurs, as can be seen from FIG. You will see an image that does not exist. This image is called a ghost or the like, and needs to be reduced.
  • the laminated optical film 100 of the present invention has a high degree of polarization, it is possible to reduce leakage of transmitted light (i.e., ghost) when a light beam is incident on the laminated optical film 100 for the first time.
  • the laminated optical film 100 of the present invention has a high degree of polarization for transmitted light, it is possible to increase the transmittance when the light rays enter the laminated optical film 100 for the second time, and the virtual image It is possible to improve the brightness of the virtual image and further suppress the tinting of the virtual image.
  • the laminated optical film 100 may be formed on a curved surface of a lens or the like.
  • a conventional optical film which is conventionally known as a reflective circular polarizer, is made by laminating a reflective linear polarizer and a retardation layer having a retardation of 1/4 wavelength. Since it has an optical axis, when it is stretched or molded into a curved shape, the optical axis is distorted and the degree of polarization of transmitted light is reduced.
  • the laminated optical film 100 of the present invention since the reflective circular polarizer (optical laminate) does not have an optical axis, the degree of polarization is less likely to decrease due to stretching or molding. Therefore, even when the laminated optical film 100 is formed into a curved shape, the degree of polarization is unlikely to decrease.
  • FIG. 1 An example of the layer structure of the laminated optical film 100 of the present invention is shown in FIG.
  • an antireflection layer 101, a positive C plate 102, a reflective circular polarizer 103, a positive C plate 104, a retardation layer 105, and a linear polarizer 106 are arranged in this order.
  • the above optical laminate is used for the reflective circular polarizer 103.
  • an antireflection layer 101, a positive C plate 102, and a positive C plate 104 are used, but some or all of the above configurations may be omitted.
  • the laminated optical film of the present invention has a reflective circular polarizer 103, a retardation layer 105 that converts circularly polarized light into linearly polarized light, and a linear polarizer 106 in this order. After converting to polarized light, it can be absorbed by a linear polarizer. Therefore, the degree of polarization of transmitted light can be increased. Note that when a laminated optical film is stretched or molded, there is a concern that the slow axis of the retardation layer or the absorption axis of the linear polarizer may be distorted. Since the reflective circular polarizer still has a high degree of polarization and the amount of leaked light from the reflective circular polarizer is small, the increase in leaked light can be suppressed to a small amount.
  • the laminated optical film of the present invention has a surface roughness Ra of 100 nm or less.
  • Ra surface roughness
  • the laminated optical film is more preferably 50 nm or less, further preferably 30 nm or less, and particularly preferably 10 nm or less.
  • the laminated optical film of the present invention is produced by laminating a large number of layers.
  • the unevenness may be amplified. Therefore, in the laminated optical film of the present invention, it is preferable that Ra is small for all layers.
  • the Ra of each layer of the laminated optical film of the present invention is preferably 50 nm or less, more preferably 30 nm or less, and even more preferably 10 nm or less. Further, from the viewpoint of increasing the image sharpness of the reflected image, it is particularly preferable that the reflective circular polarizer has a small Ra.
  • the surface roughness Ra can be measured using, for example, a non-contact surface/layer cross-sectional shape measuring system VertScan (manufactured by Ryoka System Co., Ltd.).
  • Vertscan is a surface profile measurement method that uses the phase of reflected light from a sample, so when measuring a reflective circular polarizer (the optical laminate described above) consisting of a reflective layer with a fixed cholesteric liquid crystal phase, it is necessary to use a film.
  • a metal layer may be formed on the surface of the sample in order to increase the reflectance of the surface and further suppress reflection from inside.
  • a sputtering method is used as a method for forming a metal layer on the surface of a sample.
  • Au, Al, Pt, etc. are used as the material to be sputtered.
  • the laminated optical film of the present invention preferably has a small number of point defects per unit area. Since the laminated optical film of the present invention is produced by laminating a large number of layers, in order to reduce the number of point defects in the entire laminated optical film, it is preferable that the number of point defects in each layer is also small. Specifically, the number of point defects in each layer is preferably 20 or less, more preferably 10 or less, and even more preferably 1 or less per square meter. As for the laminated optical film as a whole, the number of point defects is preferably 100 or less, more preferably 50 or less, and even more preferably 5 or less per square meter.
  • the number of point defects be small.
  • the point defects include foreign matter, scratches, dirt, film thickness variations, alignment defects of liquid crystal compounds, and the like.
  • the number of point defects mentioned above is preferably determined by counting the number of point defects having a size of 100 ⁇ m or more, more preferably 30 ⁇ m or more, and most preferably 10 ⁇ m or more.
  • the laminated optical film of the present invention is preferably transparent to near-infrared light.
  • the retardation layer used in the laminated optical film of the present invention has a function of converting the emitted light into approximately linearly polarized light when circularly polarized light is incident thereon.
  • a retardation layer in which Re is approximately 1/4 wavelength at any wavelength in the visible range can be used.
  • the in-plane retardation Re(550) at a wavelength of 550 nm is preferably 120 nm to 150 nm, more preferably 125 nm to 145 nm, even more preferably 135 nm to 140 nm.
  • a retardation layer in which Re is about 3/4 wavelength or a retardation layer in which Re is about 5/4 wavelength is also preferable because it can convert linearly polarized light into circularly polarized light.
  • the retardation layer used in the laminated optical film of the present invention has reverse dispersion with respect to wavelength. It is preferable to have inverse dispersion because circularly polarized light can be converted into linearly polarized light over a wide wavelength range in the visible region.
  • having an inverse dispersion property with respect to a wavelength means that as the wavelength becomes larger, the value of the phase difference at that wavelength becomes larger.
  • a retardation layer having reverse dispersibility can be produced by uniaxially stretching a polymer film such as a modified polycarbonate resin film having reverse dispersion, for example, with reference to JP 2017-049574 A and the like.
  • the retardation layer having reverse dispersion property only needs to have substantially reverse dispersion property, and for example, as disclosed in Japanese Patent No. 06259925, Re is approximately 1/4 wavelength. It can also be produced by laminating a retardation layer and a retardation layer with Re of about 1/2 wavelength so that their slow axes make an angle of about 60°. At this time, even if the 1/4 wavelength retardation layer and the 1/2 wavelength retardation layer each have a normal dispersion property (as the wavelength increases, the value of the retardation at the wavelength decreases), the visible range It is known that circularly polarized light can be converted into linearly polarized light over a wide wavelength range, and can be considered to have substantially inverse dispersion.
  • the laminated optical film of the present invention preferably includes a reflective circular polarizer, a quarter-wave retardation layer, a half-wave retardation layer, and a linear polarizer in this order.
  • the retardation layer used in the laminated optical film of the present invention has a layer formed by immobilizing a uniformly oriented liquid crystal compound.
  • a layer in which a rod-shaped liquid crystal compound is uniformly aligned horizontally to the in-plane direction, and a layer in which a disc-shaped liquid crystal compound is uniformly aligned perpendicular to the in-plane direction can be used.
  • a retardation layer having reverse dispersion property can be produced by uniformly orienting and fixing a rod-like liquid crystal compound having reverse dispersion property, with reference to JP-A No. 2020-084070. can.
  • the retardation layer used in the laminated optical film of the present invention has a layer formed by immobilizing a liquid crystal compound twisted and oriented with the thickness direction as the helical axis.
  • a retardation layer has a layer formed by fixing a rod-like liquid crystal compound or a disk-like liquid crystal compound twisted and oriented with the thickness direction as the helical axis. can also be used, and in this case, it is preferable because the retardation layer can be considered to have substantially reverse dispersion properties.
  • the thickness of the retardation layer is not particularly limited, but from the viewpoint of thinning, it is preferably 0.1 to 8 ⁇ m, more preferably 0.3 to 5 ⁇ m.
  • the retardation layer of the present invention may include a support, an alignment layer, etc., but the support and alignment layer may be temporary supports that are peeled off and removed when producing a laminated optical film. good.
  • the laminated optical film can be made thinner by peeling off and removing the temporary support after transferring the retardation layer to another laminate.
  • a phase difference is preferable because it can eliminate an adverse effect on the degree of polarization of transmitted light.
  • the type of support is not particularly limited, but it is preferably transparent to visible light, such as cellulose acylate, polycarbonate, polysulfone, polyethersulfone, polyacrylate, polymethacrylate, cyclic polyolefin, polyolefin, polyamide, polystyrene.
  • polyester films can be used.
  • cellulose acylate film, cyclic polyolefin, polyacrylate, or polymethacrylate is preferred. It is also possible to use commercially available cellulose acetate films (for example, "TD80U” and "Z-TAC” manufactured by Fuji Film Corporation).
  • the support is a temporary support, a support with high tear strength is preferred from the viewpoint of preventing breakage during peeling.
  • polycarbonate or polyester films are preferred.
  • the support preferably has a small retardation from the viewpoint of suppressing an adverse effect on the degree of polarization of transmitted light.
  • the magnitude of Re is preferably 10 nm or less
  • the absolute value of Rth is preferably 50 nm or less.
  • the retardation of the temporary support is is preferably small.
  • the retardation layer used in the laminated optical film of the invention is preferably transparent to near-infrared light.
  • the linear polarizer used in the laminated optical film of the present invention is preferably an absorption type linear polarizer.
  • An absorption type linear polarizer absorbs linearly polarized light in the absorption axis direction of incident light and transmits linearly polarized light in the transmission axis direction.
  • a general polarizer can be used; for example, a polarizer obtained by dyeing polyvinyl alcohol or other polymeric resin with a dichroic substance and oriented by stretching the polarizer may be used.
  • a polarizer in which a dichroic substance is oriented using the orientation of a liquid crystal compound may also be used.
  • a polarizer made of polyvinyl alcohol dyed with iodine and stretched is preferable.
  • the thickness of the linear polarizer is preferably 10 ⁇ m or less, more preferably 7 ⁇ m or less, and even more preferably 5 ⁇ m or less.
  • the single plate transmittance of the linear polarizer is preferably 40% or more, more preferably 42% or more.
  • the degree of polarization is preferably 90% or more, more preferably 95% or more, and even more preferably 99% or more.
  • the single-plate transmittance and degree of polarization of a linear polarizer are measured using an automatic polarizing film measuring device: VAP-7070 (manufactured by JASCO Corporation).
  • VAP-7070 automatic polarizing film measuring device
  • the direction of the transmission axis of the linear polarizer corresponds to the direction of the polarization axis of the light converted into linearly polarized light by the retardation layer.
  • the angle between the transmission axis of the linear polarizer and the slow axis of the retardation layer is preferably about 45°.
  • the linear polarizer used in the laminated optical film of the present invention is a light-absorbing anisotropic layer containing a liquid crystal compound and a dichroic substance.
  • a linear polarizer containing a liquid crystal compound and a dichroic substance is preferable because it can be made thinner and is less likely to crack or break even when stretched or molded.
  • the thickness of the light absorption anisotropic layer is not particularly limited, but from the viewpoint of thinning, it is preferably 0.1 to 8 ⁇ m, more preferably 0.3 to 5 ⁇ m.
  • a linear polarizer containing a liquid crystal compound and a dichroic substance can be produced, for example, with reference to JP-A-2020-023153. From the viewpoint of improving the degree of polarization of the linear polarizer, the degree of orientation of the dichroic substance in the light absorption anisotropic layer is preferably 0.95 or more, more preferably 0.97 or more.
  • the liquid crystal compound contained in the composition for forming a light absorption anisotropic layer for forming the light absorption anisotropic layer is preferably a liquid crystal compound that does not exhibit dichroism in the visible region.
  • the liquid crystal compound both low-molecular liquid crystal compounds and high-molecular liquid crystal compounds can be used.
  • the term "low-molecular liquid crystal compound” refers to a liquid crystal compound that does not have repeating units in its chemical structure.
  • polymer liquid crystal compound refers to a liquid crystal compound having repeating units in its chemical structure. Examples of the polymer liquid crystal compound include thermotropic liquid crystal polymers described in JP-A No. 2011-237513.
  • the polymeric liquid crystal compound has a crosslinkable group (for example, an acryloyl group and a methacryloyl group) at the terminal.
  • the liquid crystal compounds may be used alone or in combination of two or more. It is also preferable to use a high molecular liquid crystal compound and a low molecular liquid crystal compound together.
  • the content of the liquid crystal compound is preferably 25 to 2000 parts by mass, more preferably 33 to 1000 parts by mass, and further 50 to 500 parts by mass, based on 100 parts by mass of the dichroic substance in the composition. preferable. When the content of the liquid crystal compound is within the above range, the degree of orientation of the polarizer is further improved.
  • the dichroic substance contained in the composition for forming a light-absorbing anisotropic layer for forming a light-absorbing anisotropic layer is not particularly limited, and includes visible light-absorbing substances (dichroic dyes), ultraviolet absorbing substances, Examples include infrared absorbing substances, nonlinear optical substances, carbon nanotubes, and conventionally known dichroic substances (dichroic dyes).
  • two or more dichroic substances may be used in combination; for example, from the viewpoint of obtaining a high degree of polarization over a wider wavelength range, at least one dichroic substance having a maximum absorption wavelength in the wavelength range of 370 to 550 nm may be used. It is preferable to use the dichroic substance and at least one dichroic substance having a maximum absorption wavelength in the wavelength range of 500 to 700 nm.
  • the linear polarizer of the present invention is composed of a light-absorbing anisotropic layer containing a liquid crystal compound and a dichroic substance
  • the linear polarizer may include a support, an alignment layer, etc.
  • the body and the alignment layer may be temporary supports that are peeled off and removed when producing the laminated optical film.
  • the laminated optical film can be made thinner by peeling off and removing the temporary support after transferring the light-absorbing anisotropic layer to another laminate. This is preferable because the phase difference that the body has can eliminate the adverse effect on the degree of polarization of transmitted light.
  • the type of support is not particularly limited, but it is preferably transparent to visible light, and for example, the same support as the support used for the above-mentioned retardation layer can be used.
  • Preferred embodiments of the support used in the linear polarizer are the same as the preferred embodiments of the support used as the retardation layer.
  • the linear polarizer used in the laminated optical film of the invention is preferably transparent to near-infrared light.
  • the laminated optical film of the present invention may have other functional layers in addition to the reflective circular polarizer, retardation layer, and linear polarizer.
  • the functional layer is preferably transparent to near-infrared light.
  • the laminated optical film of the present invention further includes a positive C plate.
  • the positive C plate is a retardation layer in which Re is substantially zero and Rth is a negative value.
  • a positive C plate can be obtained, for example, by vertically aligning rod-shaped liquid crystal compounds.
  • the positive C plate functions as an optical compensation layer for increasing the degree of polarization of transmitted light with respect to obliquely incident light.
  • the positive C plate can be installed at any location on the laminated optical film, and a plurality of positive C plates may be installed.
  • the positive C plate may be placed adjacent to or inside the reflective circular polarizer.
  • the reflective layer has a positive Rth.
  • the polarization states of the reflected light and the transmitted light change due to the effect of Rth, and the degree of polarization of the transmitted light may decrease.
  • the positive C plate is preferably installed on the opposite side of the blue light reflective layer from the green light reflective layer, but may be installed at other locations.
  • the Re of the positive C plate is preferably about 10 nm or less, and the Rth is preferably -600 to -100 nm, more preferably -400 to -200 nm.
  • the positive C plate may be installed adjacent to the retardation layer or inside the retardation layer.
  • the retardation layer has a positive Rth.
  • the polarization state of the transmitted light changes due to the effect of Rth, and the degree of polarization of the transmitted light may decrease.
  • the positive C plate be installed on the opposite side of the linear polarizer to the retardation layer, but it may be installed in other locations.
  • the Re of the positive C plate is preferably about 10 nm or less, and the Rth is preferably -90 to -40 nm.
  • the laminated optical film of the present invention has an antireflection layer on the surface.
  • the laminated optical film of the present invention has the function of reflecting a specific circularly polarized light and transmitting circularly polarized light perpendicular to the specific circularly polarized light, but reflection on the surface of the laminated optical film generally includes reflection of unintended polarized light. This may reduce the degree of polarization of transmitted light. Therefore, it is preferable that the laminated optical film has an antireflection layer on the surface.
  • the antireflection layer may be installed only on one surface of the laminated optical film, or may be installed on both sides.
  • the type of antireflection layer is not particularly limited, but moth-eye film or AR (Anti-Reflective) film is preferred from the viewpoint of further reducing reflectance.
  • Known moth-eye films and AR films can be used.
  • a moth-eye film is preferred because it can maintain high antireflection performance even if the film thickness changes due to stretching.
  • the Tg peak temperature of the support is preferably 170° C. or lower in order to facilitate the stretching or molding.
  • the temperature is preferably 130°C or lower, and more preferably 130°C or lower.
  • a PMMA film or the like is preferable.
  • the laminated optical film of the present invention further includes a second retardation layer.
  • a reflective circular polarizer, a retardation layer, a linear polarizer, and a second retardation layer may be included in this order.
  • the second retardation layer converts linearly polarized light into circularly polarized light, and for example, a retardation layer having Re of 1/4 wavelength is preferable. The reason for this will be explained below.
  • the light that enters the laminated optical film from the side of the reflective circular polarizer and passes through the reflective circular polarizer, retardation layer, and linear polarizer becomes linearly polarized light, and some of it is reflected from the side of the linear polarizer.
  • the light is reflected from the outermost surface of the reflective circular polarizer and exits again from the surface on the reflective circular polarizer side.
  • Such light is unnecessary reflected light and can be a factor in reducing the degree of polarization of reflected light, so it is preferable to reduce it. Therefore, in order to suppress reflection on the outermost surface on the linear polarizer side, there is a method of laminating an antireflection layer, but when a laminated optical film is used by being attached to a medium such as glass or plastic, Even if the film has an antireflection layer on the bonding surface, it cannot prevent reflection on the surface of the medium, so it is difficult to obtain an antireflection effect.
  • a second retardation layer that converts linearly polarized light into circularly polarized light
  • the light that reaches the outermost surface on the linear polarizer side becomes circularly polarized light, and when reflected from the outermost surface of the medium, it becomes orthogonally polarized light. It is converted into circularly polarized light.
  • the second retardation layer again and reaches the linear polarizer, the light becomes linearly polarized light in the absorption axis direction of the linear polarizer, and is absorbed by the linear polarizer. Therefore, unnecessary reflection can be prevented. From the viewpoint of suppressing unnecessary reflection more effectively, it is preferable that the second retardation layer has substantially reverse dispersion.
  • the laminated optical film of the present invention may further have a support.
  • the support can be installed at any location.
  • a reflective circular polarizer, retardation layer, or linear polarizer is a film that is transferred from a temporary support
  • the support can be used as the transfer destination.
  • the type of support is not particularly limited, but it is preferably transparent to visible light, such as cellulose acylate, polycarbonate, polysulfone, polyethersulfone, polyacrylate, polymethacrylate, cyclic polyolefin, polyolefin, polyamide, polystyrene. , and polyester films can be used.
  • the support preferably has a small retardation from the viewpoint of suppressing an adverse effect on the degree of polarization of transmitted light and from the viewpoint of facilitating optical inspection of the laminated optical film.
  • the magnitude of Re is preferably 10 nm or less
  • the absolute value of Rth is preferably 50 nm or less.
  • the support When the laminated optical film of the present invention is to be stretched or molded, the support preferably has a tan ⁇ peak temperature of 170° C. or lower. From the viewpoint of enabling molding at low temperatures, the peak temperature of tan ⁇ is preferably 150°C or lower, more preferably 130°C or lower.
  • Device DVA-200 manufactured by IT Measurement Control Co., Ltd.
  • Sample 5mm, length 50mm (gap 20mm)
  • Measurement conditions Tensile mode Measurement temperature: -150°C to 220°C
  • Temperature increase condition 5°C/min
  • Frequency 1Hz
  • a resin base material that has been subjected to a stretching process is often used, and the peak temperature of tan ⁇ is often increased due to the stretching process.
  • the TAC (triacetyl cellulose) base material (“TG40", manufactured by Fuji Film Corporation) has a tan ⁇ peak temperature of 180° C. or higher.
  • various resin base materials can be used without particular limitation.
  • polyolefins such as polyethylene, polypropylene, and norbornene polymers; cyclic olefin resins; polyvinyl alcohol; polyethylene terephthalate; acrylic resins such as polymethacrylic esters and polyacrylic esters; polyethylene naphthalate; polycarbonate; polysulfone; polyether sulfone ; polyetherketone; polyphenylene sulfide and polyphenylene oxide.
  • cyclic olefin resins polyethylene terephthalate, or acrylic resins are preferred, and cyclic olefin resins or polymethacrylic acid esters are particularly preferred because they are easily available on the market and have excellent transparency. It is.
  • resin base materials include Technoloy S001G, Technoloy S014G, Technoloy S000, Technoloy C001, Technoloy C000 (Sumika Acrylic Sales Co., Ltd.), Lumirror U type, Lumirror FX10, Lumirror SF20 (Toray Industries, Ltd.), HK-53A ( Higashiyama Film Co., Ltd.), Teflex FT3 (Teijin DuPont Films Co., Ltd.), Escina'' and SCA40 (Sekisui Chemical Co., Ltd.), Zeonor Film (Optes Co., Ltd.), Arton Film (JSR Co., Ltd.), and the like.
  • the thickness of the support is not particularly limited, but is preferably 5 to 300 ⁇ m, more preferably 5 to 100 ⁇ m, and even more preferably 5 to 30 ⁇ m.
  • the laminated optical film may have layers other than the layers mentioned above.
  • layers other than those mentioned above include an adhesive layer formed using an adhesive described later, an adhesive layer formed using an adhesive described later, and a refractive index adjustment layer.
  • a refractive index adjustment layer is provided between the reflective circular polarizer and the adhesive, or between the reflective circular polarizer and the adhesive, and the difference in refractive index in the fast axis direction and the slow axis direction is smaller than that of the reflective circular polarizer. It's okay.
  • the refractive index adjusting layer preferably has a layer formed by fixing the alignment state of the cholesteric liquid crystal compound.
  • the average refractive index of the refractive index adjustment layer is smaller than the average refractive index of the reflective circular polarizer.
  • the center wavelength of the reflected light of the refractive index adjusting layer may be smaller than 430 nm or larger than 670 nm, and is more preferably smaller than 430 nm.
  • the laminated optical film of the present invention is a laminate consisting of a large number of layers.
  • Each layer can be adhered by any adhesive method, for example, adhesives and adhesives can be used.
  • the adhesive any commercially available adhesive can be used, but from the viewpoint of thinning and reducing the surface roughness Ra of the laminated optical film, the thickness is preferably 25 ⁇ m or less, and 15 ⁇ m or less. The thickness is more preferably 6 ⁇ m or less, and most preferably 6 ⁇ m or less. Moreover, it is preferable that the adhesive is one that does not easily generate outgas.
  • the adhesive any commercially available adhesive can be used.
  • an epoxy resin adhesive or an acrylic resin adhesive can be used.
  • the thickness of the adhesive is preferably 25 ⁇ m or less, more preferably 5 ⁇ m or less, and preferably 1 ⁇ m or less from the viewpoint of thinning and reducing the surface roughness Ra of the laminated optical film. most preferred.
  • the adhesive preferably has a viscosity of 300 cP or less, more preferably 100 cP or less, and 10 cP or less, from the viewpoint of thinning the adhesive layer and applying the adhesive to the adherend with a uniform thickness.
  • the pressure-sensitive adhesive and the adhesive should be used in such a way that they can embed the surface irregularities of the layer to be adhered, from the viewpoint of reducing the surface roughness Ra of the laminated optical film.
  • Appropriate viscoelasticity or thickness can also be selected. From the viewpoint of embedding surface irregularities, it is preferable that the adhesive and the adhesive have a viscosity of 50 cP or more. Further, the thickness is preferably thicker than the height of the surface irregularities. Examples of methods for adjusting the viscosity of the adhesive include a method using an adhesive containing a solvent. In this case, the viscosity of the adhesive can be adjusted by adjusting the ratio of solvents. Furthermore, by drying the solvent after applying the adhesive to the adherend, the thickness of the adhesive can be further reduced.
  • the pressure-sensitive adhesive or adhesive used to bond each layer should have a refractive index difference between adjacent layers.
  • the refractive index difference between adjacent layers is preferably 0.1 or less, more preferably 0.05 or less, and even more preferably 0.01 or less.
  • the refractive index of the pressure-sensitive adhesive or adhesive can be adjusted, for example, by mixing fine particles such as titanium oxide fine particles and zirconia fine particles.
  • reflective circular polarizers, retardation layers, and linear polarizers may have refractive index anisotropy in the plane, but the refractive index difference between adjacent layers in all directions in the plane is It is preferable that it is 0.05 or less. Therefore, the adhesive and the adhesive may have in-plane refractive index anisotropy.
  • the adhesive layer between each layer has a thickness of 100 nm or less.
  • the thickness of the adhesive layer is more preferably 50 nm or less.
  • An example of a method for forming an adhesive layer having a thickness of 100 nm or less is a method of vapor depositing a ceramic adhesive such as silicon oxide (SiOx layer) on the bonding surface.
  • the bonding surface of the bonding member can be subjected to surface modification treatment such as plasma treatment, corona treatment, saponification treatment, etc.
  • an adhesive layer having a thickness of 100 nm or less can be provided by following the steps (1) to (3) below.
  • (1) Layers to be laminated are bonded to a temporary support made of a glass base material.
  • the vapor deposition can be performed using SiOx powder as a vapor deposition source, for example, using a vapor deposition apparatus manufactured by ULVAC (model number ULEYES). Further, it is preferable to perform plasma treatment on the surface of the formed SiOx layer. (3) After bonding the formed SiOx layers together, the temporary support is peeled off. It is preferable that the lamination is carried out at a temperature of, for example, 120°C.
  • the coating, adhesion, or lamination of each layer may be performed in a roll-to-roll manner, or may be performed in sheets.
  • the roll-to-roll method is preferable from the viewpoint of improving productivity and reducing axis misalignment of each layer.
  • the single-wafer method is preferable because it is suitable for small-volume, high-mix production, and because it allows the selection of a special adhesive method such as the above-mentioned adhesive layer having a thickness of 100 nm or less.
  • methods for applying the adhesive to the adherend include, for example, roll coating method, gravure printing method, spin coating method, wire bar coating method, extrusion coating method, direct gravure coating method, reverse gravure coating method, die coating method, etc.
  • Known methods include a method, a spray method, and an inkjet method.
  • each layer It is also preferable not to have an adhesive layer between each layer of the laminated optical film of the present invention.
  • the adhesion layer can be eliminated by applying it directly onto an adjacent layer that has already been formed.
  • the alignment direction of the liquid crystal compound changes continuously at the interface in order to reduce the difference in refractive index in all directions within the plane.
  • a retardation layer containing a liquid crystal compound is directly applied to a linear polarizer containing a liquid crystal compound and a dichroic substance, and the liquid crystal compound in the retardation layer is They can also be oriented so that they are continuous at the interface.
  • the laminated optical film of the present invention consists of a large number of layers
  • the order of the steps for laminating them is not particularly limited and can be arbitrarily selected.
  • wrinkles and cracks during transfer can be avoided by adjusting the stacking order so that the thickness of the transferred film is 10 ⁇ m or more. It can be prevented.
  • the surface irregularities may be further amplified. It is preferable to stack the layers in order from the smallest layer.
  • the order of lamination can be selected from the viewpoint of quality evaluation in the process of producing a laminated optical film. For example, after layers excluding the reflective circular polarizer are laminated and quality evaluation is performed using a transmission optical system, a reflective circular polarizer can be laminated and quality evaluation is performed using a reflective optical system. Further, the order of lamination can be selected from the viewpoint of improving the manufacturing yield of the laminated optical film or reducing the cost.
  • the laminated optical film of the present invention can be used, for example, as a reflective polarizer incorporated into a vehicle-mounted rearview mirror, a virtual reality display device, an electronic finder, etc., as described in Patent Documents 4 to 5.
  • the laminated optical film of the present invention improves the clarity of displayed images in virtual reality display devices and electronic viewfinders that have a reciprocating optical system that reflects light between a reflective polarizer and a half mirror. It is very useful from the perspective of improving.
  • having reciprocating optical systems may have optical films such as absorptive polarizers and circular polarizers in addition to reflective polarizers, but the laminated optical film of the present invention
  • optical films such as absorptive polarizers and circular polarizers in addition to reflective polarizers, but the laminated optical film of the present invention
  • a reflective layer coating liquid R-1 for reflective layer was prepared by stirring and dissolving the composition shown below in a container kept at 70°C.
  • R represents a coating liquid using a rod-like liquid crystal compound.
  • the numerical values are mass %.
  • R is a group bonded through an oxygen atom.
  • the average molar extinction coefficient of the rod-like liquid crystal compound at a wavelength of 300 to 400 nm was 140/mol ⁇ cm.
  • Chiral agent A is a chiral agent whose helical twisting power (HTP) is reduced by light.
  • ⁇ Coating liquid for reflective layer R-2 to R-6> It was prepared in the same manner as reflective layer coating liquid R-1, except that the amount of chiral agent A added was changed as shown in Table 1 below.
  • a reflective layer coating liquid D-1 for reflective layer was prepared by stirring and dissolving the composition shown below in a container kept at 50°C.
  • D represents a coating liquid using a discotic liquid crystal compound.
  • ⁇ Coating liquid for reflective layer D-2 to D-5> It was prepared in the same manner as reflective layer coating liquid D-1, except that the amount of chiral agent A added was changed as shown in Table 2 below.
  • the surface of the PET film shown above without the easy-adhesion layer was subjected to a rubbing treatment, and the reflective layer coating liquid R-1 prepared above was applied using a wire bar coater, and then the coating film was dried at 110° C. for 120 seconds. Thereafter, the cholesteric liquid crystal layer is cured by irradiating the coating film with light from a metal halide lamp with an illumination intensity of 80 mW/cm 2 and an irradiation amount of 500 mJ/cm 2 at 100° C. in a low oxygen atmosphere (100 ppm or less). A yellow light reflective layer (first light reflective layer) was formed. Light irradiation was performed from the cholesteric liquid crystal layer side in all cases. At this time, the coating thickness was adjusted so that the thickness of the yellow light reflective layer after curing was 2.5 ⁇ m.
  • the surface of the yellow light reflective layer was subjected to corona treatment with a discharge amount of 150 W min/m 2 , and then coating liquid D-1 for reflective layer was applied to the corona treated surface using a wire bar coater. did.
  • the coating film was dried at 70° C. for 2 minutes to vaporize the solvent, and then heated and aged at 115° C. for 3 minutes to obtain a uniform orientation state. Thereafter, this coating film was maintained at 45°C and cured by irradiating it with ultraviolet light (300 mJ/cm 2 ) using a metal halide lamp in a nitrogen atmosphere. A second light-reflecting layer) was formed. Light irradiation was performed from the cholesteric liquid crystal layer side in all cases. At this time, the coating thickness was adjusted so that the thickness of the green light reflective layer after curing was 2.4 ⁇ m.
  • reflective layer coating liquid R-2 was applied onto the green light reflective layer using a wire bar coater, and then dried at 110° C. for 120 seconds. Thereafter, the coating film is cured by irradiating it with light from a metal halide lamp at 100°C in a low oxygen atmosphere (100 ppm or less) with an illuminance of 80 mW and an irradiation amount of 500 mJ/ cm2 , so that a red color appears on the green light reflective layer. A light reflective layer (third light reflective layer) was formed. Light irradiation was performed from the cholesteric liquid crystal layer side in all cases. At this time, the coating thickness was adjusted so that the thickness of the red light reflective layer after curing was 2.4 ⁇ m.
  • the surface of the red light reflective layer was subjected to corona treatment at a discharge amount of 150 W min/m 2 , and then reflective layer coating liquid D-2 was applied to the corona treated surface using a wire bar coater. .
  • the coating film was dried at 70° C. for 2 minutes to vaporize the solvent, and then heated and aged at 115° C. for 3 minutes to obtain a uniform orientation state. Thereafter, this coating film was held at 45°C and cured by irradiating it with ultraviolet light (300 mJ/cm 2 ) using a metal halide lamp in a nitrogen atmosphere. 4) was formed. Light irradiation was performed from the cholesteric liquid crystal layer side in all cases. At this time, the coating thickness was adjusted so that the film thickness of the blue light reflective layer after curing was 2.6 ⁇ m.
  • Reflective circular polarizers 2 and 4 were manufactured by the same method as reflective circular polarizer 1, except that the coating liquid for the reflective layer and the film thickness were changed as shown in the following tables (Tables 3 and 4).
  • Reflective circular polarizer 3 was fabricated using the following fabrication procedure by changing the coating liquid for the reflective layer and the film thickness as shown in the following tables (Tables 3 and 4).
  • the surface of the PET film shown above without the easy-adhesion layer was subjected to a rubbing treatment, and the reflective layer coating liquid R-1 prepared above was applied using a wire bar coater, and then the coating film was dried at 110° C. for 120 seconds. Thereafter, the cholesteric liquid crystal layer is cured by irradiating the coating film with light from a metal halide lamp with an illuminance of 80 mW/cm 2 and an irradiation amount of 500 mJ/cm 2 at 100° C. in a low oxygen atmosphere (100 ppm or less). A yellow light reflective layer (first light reflective layer) was formed. Light irradiation was performed from the cholesteric liquid crystal layer side in all cases. At this time, the coating thickness was adjusted so that the thickness of the yellow light reflective layer after curing was 2.5 ⁇ m.
  • coating liquid R-5 for reflective layer was applied onto the yellow light reflective layer using a wire bar coater, and the coating film was dried at 110° C. for 120 seconds. Thereafter, in a low oxygen atmosphere (100 ppm or less) at 100°C, the coating film is cured by irradiation with light from a metal halide lamp with an illuminance of 80 mW and an irradiation amount of 500 mJ/ cm2 , so that a green color appears on the yellow light reflective layer. A light reflective layer (second light reflective layer) was formed. Light irradiation was performed from the cholesteric liquid crystal layer side in all cases. At this time, the coating thickness was adjusted so that the thickness of the green light reflective layer after curing was 2.4 ⁇ m.
  • coating liquid R-2 for reflective layer was applied onto the green light reflective layer using a wire bar coater, and the coating film was dried at 110° C. for 120 seconds. Thereafter, the coating film is cured by irradiating it with light from a metal halide lamp at 100°C in a low oxygen atmosphere (100 ppm or less) with an illuminance of 80 mW and an irradiation amount of 500 mJ/ cm2 , so that a red color appears on the green light reflective layer. A light reflective layer (third light reflective layer) was formed. Light irradiation was performed from the cholesteric liquid crystal layer side in all cases. At this time, the coating thickness was adjusted so that the thickness of the red light reflective layer after curing was 2.4 ⁇ m.
  • coating liquid R-6 for reflective layer was applied onto the red light reflective layer using a wire bar coater, and the coated film was dried at 110° C. for 120 seconds. Thereafter, the coating film is cured by irradiating it with light from a metal halide lamp at 100°C in a low oxygen atmosphere (100 ppm or less) with an illumination intensity of 80 mW and an irradiation amount of 500 mJ/ cm2 , so that the blue color appears on the red light reflective layer. A light reflective layer (fourth light reflective layer) was formed. Light irradiation was performed from the cholesteric liquid crystal layer side in all cases. At this time, the coating thickness was adjusted so that the thickness of the blue light reflective layer after curing was 2.6 ⁇ m.
  • Coating liquid used for producing reflective circular polarizers 1 to 4 In the table below, the coating liquid for the reflective layer is omitted, for example, the coating liquid for the reflective layer is written as "Liquid R-1". It is written as In addition, in the table, “1st layer” refers to the first light reflective layer, “2nd layer” refers to the second light reflective layer, “3rd layer” refers to the third light reflective layer, and “4th layer” refers to the second light reflective layer. "eyes" respectively indicate the fourth light-reflecting layer.
  • Table 3 shows the characteristics of the manufactured reflective circular polarizers 1 to 4.
  • the reflection center wavelength (center wavelength of reflected light) and Rth of each layer were confirmed by measuring the characteristics of a film produced by coating only a single layer.
  • the reflection center wavelength is used to define the characteristics of a light reflective film having a reflection band using a cholesteric liquid crystal phase, and refers to the midpoint of the spectral band reflected by the film. Specifically, it was obtained by calculating the average value of the wavelength on the short wavelength side and the wavelength on the long wavelength side, which are half the value of the peak reflectance, using the method described above.
  • the sign of Rth of the first light reflective layer and the sign of Rth of the second light reflective layer are opposite, and the sign of Rth of the third light reflective layer is opposite to the sign of Rth of the second light reflective layer.
  • the sign of Rth of the light-reflecting layer of No. 4 was opposite, and the sign of Rth of the second light-reflecting layer and the sign of Rth of the third light-reflecting layer were opposite.
  • the signs of Rth of the first to fourth light reflective layers were all the same.
  • a laminated optical film was produced using the following procedure.
  • a reverse dispersion retardation layer 1 was produced with reference to the method described in paragraphs 0151 to 0163 of JP-A-2020-084070.
  • outer layer cellulose acylate dope 10 parts by mass of the following matting agent solution was added to 90 parts by mass of the core layer cellulose acylate dope to prepare a cellulose acetate solution to be used as the outer layer cellulose acylate dope.
  • Matting agent solution - 2 parts by mass of silica particles with an average particle size of 20 nm (AEROSIL R972, manufactured by Nippon Aerosil Co., Ltd.) - 76 parts by mass of methylene chloride (first solvent) - 11 parts by mass of methanol (second solvent) -
  • AEROSIL R972 manufactured by Nippon Aerosil Co., Ltd.
  • cellulose acylate film 1- After filtering the core layer cellulose acylate dope and the outer layer cellulose acylate dope through a filter paper with an average pore size of 34 ⁇ m and a sintered metal filter with an average pore size of 10 ⁇ m, the core layer cellulose acylate dope and the outer layer cellulose acylate dope are placed on both sides. Three layers of the above were simultaneously cast from a casting port onto a drum at 20°C (band casting machine). Next, the film was peeled off with a solvent content of approximately 20% by mass, and both ends of the film in the width direction were fixed with tenter clips, and the film was dried while being stretched in the transverse direction at a stretching ratio of 1.1 times.
  • cellulose acylate film 1 The in-plane retardation of the obtained cellulose acylate film 1 was 0 nm.
  • Coating liquid S-PA-1 for forming an alignment layer was continuously applied onto the cellulose acylate film 1 using a wire bar.
  • the support on which the coating film has been formed is dried with hot air at 140°C for 120 seconds, and then the coating film is irradiated with polarized ultraviolet light (10 mJ/cm 2 , using an ultra-high pressure mercury lamp) to form a photo-alignment layer.
  • PA1 was formed.
  • the film thickness was 0.3 ⁇ m.
  • the following coating liquid SP-1 for forming a light-absorbing anisotropic layer was continuously applied with a wire bar.
  • the coating layer P1 was heated at 140° C. for 30 seconds, and the coating layer P1 was cooled to room temperature (23° C.). Then, it was heated at 90° C. for 60 seconds and cooled to room temperature again. Thereafter, the light absorption anisotropic layer P1 was formed on the alignment layer PA1 by irradiating for 2 seconds using an LED lamp (center wavelength 365 nm) at an illuminance of 200 mW/cm 2 .
  • the film thickness was 1.6 ⁇ m.
  • composition of coating liquid SP-1 for forming light-absorbing anisotropic layer ⁇ ⁇
  • the following dichroic substance D-1 0.25 parts by mass ⁇
  • the following dichroic substance D-2 0.36 parts by mass ⁇
  • the following dichroic substance D-3 0.59 parts by mass ⁇
  • the following polymeric liquid crystal compound M- P-1 2.21 parts by mass ⁇ Low molecular liquid crystal compound below M-1 1.36 parts by mass ⁇ Polymerization initiator "IRGACURE (registered trademark) OXE-02" (manufactured by BASF) 0.200 parts by mass - Surfactant F-1 below 0.026 parts by mass - Cyclopentanone 46.00 parts by mass - Tetrahydrofuran 46.00 parts by mass - Benzyl alcohol 3.00 parts by mass --- ⁇
  • the reflection circular polarizer 1 was bonded thereon using a laminator so that the opposite side of the temporary support was in contact with the UV adhesive.
  • the reflective circular polarizer 1 was cured by irradiation with ultraviolet rays from a high-pressure mercury lamp from the temporary support side.
  • the illumination intensity was 25 mW/cm 2 and the irradiation amount was 1000 mJ/cm 2 .
  • the temporary support of reflective circular polarizer 1 was peeled off.
  • the positive C plate 2 was bonded to the first light reflective layer side of the reflective circular polarizer 1.
  • the retardation layer 1 was bonded to the positive C plate 2.
  • the light-absorbing anisotropic layer P1 was transferred to the retardation layer 1 using the same transfer procedure as described above. However, the layers are stacked so that the slow axis of the retardation layer 1 and the absorption axis of the light absorption anisotropic layer P1 form an angle of 45°, and the polarization axis of the light emitted from the retardation layer 1 and the light absorption anisotropic layer
  • the transmission axis of the transparent layer P1 was made to be parallel to the transmission axis. In this way, a laminated optical film using the reflective circular polarizer 1 of Example 1 was obtained.
  • a black and white checker pattern was displayed on the image display panel, and ghost visibility was visually evaluated on the following three scales.
  • Example 2 Furthermore, the laminated optical films of Example 2, Comparative Example 1, and Comparative Example 2 were each produced using the same procedure, and the ghost visibility was evaluated.
  • Table 5 shows the types of reflective circular polarizers used in each example and comparative example. The evaluation results are shown in Table 6. As a result, in the virtual reality display devices of Examples 1 and 2, no ghost was visible over the entire area of the lens.
  • Examples 3-4, Comparative Examples 3-4 In the procedure for obtaining the laminated optical film used in Example 1 above, instead of transferring the reflective circular polarizer 1 to the positive C plate 1, it was temporarily transferred to a laminate film with a weak adhesive layer, and the positive C plate 1 was laminated. A reflective circular polarizer 1 was obtained which was not attached to a laminate film. A laminated optical film used in Example 3 was obtained by performing the same procedure as in Example 1 except for using the obtained reflective circular polarizer 1 with a laminate film, and finally peeling off the laminate film.
  • Example 2 In addition, in the procedure for obtaining the laminated optical film used in Example 2, instead of transferring the reflective circular polarizer 2 to the positive C plate 1, it was temporarily transferred to a laminate film with a weak adhesive layer, and the reflective circular polarizer 2 was temporarily transferred to the laminate film with a weak adhesive layer. A reflective circular polarizer 2 was obtained in which the reflective circular polarizer 2 was not laminated but was bonded to a laminate film. A laminated optical film used in Example 4 was obtained by performing the same procedure as in Example 2 except for using the obtained reflective circular polarizer 2 with a laminate film, and finally peeling off the laminate film.
  • a reflective circular polarizer 4 was obtained in which the reflective circular polarizer 4 was not laminated but was bonded to a laminate film.
  • a laminated optical film used in Comparative Example 4 was obtained by performing the same procedure as in Comparative Example 2 except for using the obtained reflective circular polarizer 4 with a laminate film, and finally peeling off the laminate film.

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WO2015029958A1 (ja) * 2013-08-26 2015-03-05 富士フイルム株式会社 輝度向上フィルム、光学シート部材および液晶表示装置
WO2022075475A1 (ja) * 2020-10-09 2022-04-14 富士フイルム株式会社 積層光学フィルムおよび画像表示装置
WO2022260134A1 (ja) * 2021-06-10 2022-12-15 富士フイルム株式会社 光学用積層体、積層光学フィルム、光学物品、仮想現実表示装置

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JP7808629B2 (ja) 2024-02-19 2026-01-29 日東電工株式会社 表示システムおよび表示体

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