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WO2018012469A1 - Membrane de réflexion sélective en longueur d'onde, film optique, procédé de fabrication d'une membrane de réflexion sélective en longueur d'onde, et dispositif d'affichage d'image - Google Patents

Membrane de réflexion sélective en longueur d'onde, film optique, procédé de fabrication d'une membrane de réflexion sélective en longueur d'onde, et dispositif d'affichage d'image Download PDF

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Publication number
WO2018012469A1
WO2018012469A1 PCT/JP2017/025179 JP2017025179W WO2018012469A1 WO 2018012469 A1 WO2018012469 A1 WO 2018012469A1 JP 2017025179 W JP2017025179 W JP 2017025179W WO 2018012469 A1 WO2018012469 A1 WO 2018012469A1
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WIPO (PCT)
Prior art keywords
wavelength
film
liquid crystal
reflection
optical film
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Ceased
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PCT/JP2017/025179
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English (en)
Japanese (ja)
Inventor
匡広 渥美
二村　恵朗
齊藤　之人
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Fujifilm Corp
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Fujifilm Corp
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Priority to JP2018527601A priority Critical patent/JP6723359B2/ja
Publication of WO2018012469A1 publication Critical patent/WO2018012469A1/fr
Anticipated expiration legal-status Critical
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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/20—Filters
    • G02B5/26—Reflecting filters
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/13363—Birefringent elements, e.g. for optical compensation
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B21/00—Projectors or projection-type viewers; Accessories therefor
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B21/00—Projectors or projection-type viewers; Accessories therefor
    • G03B21/54—Accessories
    • G03B21/56—Projection screens
    • G03B21/60—Projection screens characterised by the nature of the surface

Definitions

  • the present invention relates to a wavelength selective reflection film that selectively reflects a specific wavelength and a method for manufacturing the same.
  • the present invention also relates to an optical film provided with a wavelength selective reflection film, and an image display device.
  • a head-up display (HUD) screen used in car navigation or the like is required to have both high external light transmittance and high reflectivity of a projected image.
  • the transmittance and reflectance of incident light are 1 (100%) in total in the simple half mirror regardless of the wavelength, it is possible to achieve both high transmittance of external light and high reflectance of the projected image. Have difficulty.
  • liquid crystal display devices such as liquid crystal display devices (hereinafter also referred to as LCDs) consume less power and are increasingly used as space-saving image display devices year by year.
  • the liquid crystal display device has a configuration in which a backlight (hereinafter also referred to as BL), a backlight side polarizing plate, a liquid crystal cell, a viewing side polarizing plate, and the like are provided in this order.
  • the reflective polarizer is an optical element that transmits only light oscillating in a specific polarization direction among light incident while oscillating in all directions, and reflects light oscillating in other polarization directions. This makes it possible to recycle the light that is reflected without being reflected by the reflective polarizer, thereby improving the light utilization efficiency in the LCD.
  • a structure in which layers formed by fixing a cholesteric liquid crystal phase are laminated is known. Since the cholesteric liquid crystal phase exhibits circularly polarized light reflectivity at a wavelength corresponding to the helical pitch, it is possible to widen the reflection wavelength region by laminating a plurality of layers having different pitches.
  • Japanese Patent Application Laid-Open No. 1-133003 discloses a reflective polarizing plate having a structure in which a ⁇ / 4 plate and a layer in which a cholesteric liquid crystal phase is fixed are laminated, and three or more cholesteric liquid crystal phases having different cholesteric liquid crystal phase pitches. A technique for improving the light utilization factor of BL by broadening the reflection wavelength region by using a fixed layer is described.
  • a rod-like liquid crystal compound is generally used as a cholesteric liquid crystal material, but it is also possible to align a discotic liquid crystal in a spiral shape.
  • a reflective function similar to that of a cholesteric liquid crystal phase using a rod-like liquid crystal compound can be provided.
  • Discotic liquid crystals having a spiral structure are described in, for example, Japanese Patent Application Laid-Open Nos. 2001-81465 and 2015-194675.
  • the reflection wavelength band of the reflection polarizer that has been used to improve the light utilization rate of the conventional BL is that of the reflection polarizer of about three layers having different reflection center wavelengths.
  • the reflection wavelength band per layer is wide enough to reflect almost all visible light in the laminate, so that the reflection wavelength band is too wide to be applied to a HUD screen, and the transmittance of outside light is low. There was a problem that it could not be obtained sufficiently.
  • the narrower the reflection wavelength region of the wavelength selective reflection film the better the overall transmittance.
  • the present invention has been made in view of the above circumstances, and provides a wavelength-selective reflective film suitable for a reflective display device that performs image display using reflected light on a translucent screen such as a HUD, and a method for manufacturing the same.
  • Another object of the present invention is to provide an optical film and an image display device provided with a wavelength selective reflection film.
  • the first wavelength-selective reflective film of the present invention is a biaxially stretched film of an optical film in which a discotic liquid crystal compound is fixed in a cholesteric phase state, and the half-value width of the reflected wavelength region is 40 nm or less.
  • the second wavelength-selective reflective film of the present invention is a wavelength-selective reflective film in which a discotic liquid crystal compound is fixed in a cholesteric phase state, the half-value width of the reflected wavelength region is 40 nm or less, and the reflection center wavelength
  • the thickness direction retardation Rth at a wavelength of +100 nm is ⁇ 50 nm or more.
  • the first optical film of the present invention comprises the wavelength selective reflection film of the present invention and a ⁇ / 4 plate laminated on one surface of the wavelength selective reflection film.
  • the second optical film of the present invention is characterized by comprising a plurality of laminated films of the wavelength-selective reflecting films of the present invention having reflection wavelength regions having different reflection center wavelengths. At this time, a ⁇ / 4 plate laminated on one surface of the laminated film may be further provided.
  • the method for producing a wavelength selective reflection film of the present invention comprises forming an optical film in which a discotic liquid crystal compound is fixed in a cholesteric phase state, and biaxially stretching the optical film so that the half-value width of the reflection wavelength region is 40 nm or less. A certain wavelength-selective reflecting film is obtained.
  • a polymerizable liquid crystal composition containing a discotic liquid crystal compound is applied on a support to form a coating film, Curing the coating film after maintaining the coating film for a certain time at a temperature 1 to 15 ° C. lower than the transition temperature between the liquid crystal phase and the isotropic phase of the polymerizable liquid crystal composition to bring the discotic liquid crystal compound into a cholesteric phase state.
  • the biaxial stretching ratio is preferably 20% to 50%.
  • the image display device of the present invention projects a video onto a light-transmitting screen, the wavelength-selective reflective film of the present invention attached to the surface of the screen, and the screen with the wavelength-selective reflective film attached thereto.
  • a liquid crystal projection device is provided.
  • the wavelength-selective reflecting film of the present invention has a very narrow half-value width of 40 nm or less in the reflection wavelength region, and is therefore suitable for an embodiment that selectively reflects a narrow band wavelength such as HUD.
  • a numerical range expressed using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.
  • the “half width” of a peak means the width of the peak at a peak height of 1/2.
  • the reflection center wavelength and half-value width of the reflective polarizer can be measured with an integral reflectometer.
  • measurement is performed using a spectrophotometer V-550 connected to an integrating sphere device ILV-471 (both manufactured by JASCO Corporation) as an integrating reflectometer.
  • Re ( ⁇ ) and Rth ( ⁇ ) each represent in-plane retardation and thickness direction retardation at wavelength ⁇ .
  • Re ( ⁇ ) and Rth ( ⁇ ) are values measured at wavelength ⁇ in AxoScan (manufactured by Axometrics).
  • the in-plane retardation is a value measured by making light of wavelength ⁇ incident on the film from the normal direction of the film surface.
  • Thickness direction retardation Rth ( ⁇ ) ((Nx + Ny) / 2 ⁇ Nz) ⁇ d Is calculated.
  • Wavelength selective reflective film >> The wavelength selective reflection film of the present invention will be described.
  • the wavelength-selective reflective film of the present invention is a biaxially stretched film obtained by biaxially stretching an optical film in which a discotic liquid crystal compound is fixed in a cholesteric phase state.
  • "Reflected wavelength half width" is 40 nm or less. Preferably they are 20 nm or more and 40 nm or less. By setting it to 20 nm or more, it is preferable because no loss occurs in reflection without becoming narrower than the half width of the LED light source that can be used as a light source of incident light.
  • the optical film in which the discotic liquid crystal compound is fixed in the cholesteric phase state usually has a thickness direction retardation Rth of ⁇ 100 nm or less, but the thickness direction retardation Rth in the wavelength selective reflection film of the present invention is ⁇ It is 50 nm or more.
  • Rth is preferably larger than ⁇ 50 nm, and may take a positive value of 0 or more.
  • the relationship between the Rth and the half-value width of the reflection wavelength is not clear at the present time.
  • the Rth is simply an index as to whether or not stretching has been performed.
  • the wavelength-selective reflecting film of the present invention is a light having a wavelength band of a half-value width of 40 nm or less having a center wavelength of reflection corresponding to right-handed circularly polarized light or left-handed circularly polarized light according to the spiral direction of the cholesteric phase. To selectively reflect.
  • An optical film before stretching in which a discotic liquid crystal compound is fixed in a cholesteric phase corresponds to a reflective polarizer having wavelength selectivity in a conventional LCD.
  • the present inventors have found that the half-width of the reflection wavelength of this optical film is approximately 60 nm or more, but the half-width of the reflection wavelength can be reduced to 40 nm or less by biaxially stretching the optical film.
  • P is a helical pitch (film thickness at which the discotic liquid crystal compound (liquid crystal molecule) rotates once) in the cholesteric structure. Therefore, in principle, it is clear that the reflection wavelength region can be narrowed by reducing ⁇ n of the discotic liquid crystal compound. However, it has been difficult to obtain a small ⁇ n by molecular design or the like. The present inventors have found that the apparent ⁇ n can be reduced and the reflection wavelength half-value width ⁇ can be reduced by biaxially stretching an optical film in which the discotic liquid crystal compound is fixed in a cholesteric phase state. It was.
  • the present invention is characterized in that, by biaxially stretching an optical film in which a discotic liquid crystal compound is fixed in a cholesteric phase state, the reflection half width can be reduced, and 40 nm or less is realized.
  • the wavelength selective reflection film of the present invention is a biaxially stretched film of an optical film in which a discotic liquid crystal compound is fixed in a cholesteric phase state.
  • an optical film having a discotic liquid crystal compound fixed in a cholesteric phase has not been realized with a reflection half-value width of 40 nm or less.
  • the inventors have found that the wavelength band changes before and after the optical film is stretched, and also that the negative Rth changes to the positive side due to stretching.
  • An optical film in which the discotic liquid crystal compound before stretching is fixed in a cholesteric phase state generally shows Rth of ⁇ 100 nm or less, but when the optical film is stretched, Rth shifts to the positive side.
  • the relationship between the wavelength band of the wavelength selective reflection film and Rth is not clear at present.
  • the wavelength-selective reflecting film of the present invention reflects light having a reflection center wavelength determined according to the pitch of the cholesteric phase and the refractive index of the discotic liquid crystal compound and the wavelength band in the vicinity of right-handed circularly polarized light or left-handed circularly polarized light. Can do.
  • the wavelength giving the peak of reflectivity (ie, the reflection center wavelength) can be adjusted by changing the pitch or refractive index of the cholesteric phase helical structure, but changing the pitch can be done by changing the amount of chiral agent added. It can be easily adjusted. Specifically, Fujifilm research report No. 50 (2005) p. There is a detailed description in 60-63.
  • the reflection center wavelength of the wavelength selective reflection film is shifted to the shorter wavelength side than the reflection center wavelength of the optical film before biaxial stretching. Therefore, it is necessary to set the composition of the polymerizable liquid crystal compound for forming an optical film in consideration of the shift amount of the reflection center wavelength due to biaxial stretching.
  • FIG. 1 is a schematic cross-sectional view of an embodiment of a wavelength selective reflection film.
  • the wavelength selective reflection film 13 of this embodiment is provided on one surface of the support 2.
  • the support 2 is essential for the wavelength-selective reflective film 13 during film formation.
  • An alignment layer may be provided between the support 2 and the wavelength selective reflection film 13.
  • the wavelength selective reflection film 13 may be used as the optical film 1 together with the support 2, or may be peeled off from the support 2 and transferred to another substrate via an adhesive layer. .
  • the wavelength-selective reflective film of the present invention exhibits reflectivity only with respect to a narrow wavelength band having a reflection wavelength half-width of 40 nm or less, so that the head-up display (HUD) used in car navigation etc. It is suitable for an image display device that displays a projected image by reflected light on a translucent screen that transmits light.
  • a wavelength-selective reflection film whose reflection wavelength band matches the output wavelength of the image projection device By attaching a wavelength-selective reflection film whose reflection wavelength band matches the output wavelength of the image projection device to the surface of the translucent screen, the wavelength range with high transmittance is widened to increase the overall transmittance. It is possible to construct an image display device having a high reflectivity with respect to the wavelength from the projection device while increasing.
  • FIG. 2 is a schematic cross-sectional view showing an embodiment of the optical film of the present invention.
  • the optical film 10 of the present embodiment is formed by laminating the wavelength selective reflection film 13 described above on a ⁇ / 4 plate 12 with an adhesive layer 20 interposed therebetween.
  • the ⁇ / 4 plate 12 when the light desired to be reflected by the wavelength selective reflection film 13 is linearly polarized light, the ⁇ / 4 plate 12 converts the light into circularly polarized light that can be reflected by the wavelength selective reflection film 13. Since the light can be incident on the wavelength selective reflection film 13 after conversion, the reflection efficiency can be increased.
  • FIG. 3 is a schematic cross-sectional view showing another embodiment of the optical film of the present invention.
  • the optical film 11 of the present embodiment includes a laminated film 14 of a first wavelength selective reflection film 13a, a second wavelength selective reflection film 13b, and a third wavelength selective reflection film 13c.
  • the ⁇ / 4 plate 12 is laminated via an adhesive layer 20.
  • Each of the first to third wavelength-selective reflecting films 13a to 13c is the wavelength-selective reflecting film of the present invention, and any one of the reflectances has a reflection center wavelength of 380 to 499 nm and a half width of 40 nm or less.
  • a blue reflective layer having a peak any one of which is a green reflective layer having a reflectance peak having a reflection center wavelength of 500 to 599 nm and a half width of 40 nm or less, and any one of which is a reflection center wavelength of 600 to 750 nm and a half
  • a red reflective layer having a reflectance peak with a value width of 40 nm or less is preferred.
  • full-color image display can be performed.
  • the reflection center wavelength of the blue reflective layer is preferably in the wavelength band of 430 to 480 nm, and more preferably in the wavelength band of 430 to 470 nm.
  • the reflection center wavelength of the green reflective layer is preferably in the wavelength band of 520 to 590 nm, and more preferably in the wavelength band of 520 to 580 nm.
  • the reflection center wavelength of the red reflective layer is preferably in the wavelength band of 610 to 690 nm, and more preferably in the wavelength band of 610 to 660 nm.
  • the center wavelength in each reflective layer may be set according to the wavelength on the light source side that outputs incident light such as a projection device.
  • each cholesteric phase spiral structure of the first to third wavelength selective reflection films is not particularly limited, but the spiral direction of each cholesteric phase of the first to third wavelength selective reflection films is It is preferable that they match.
  • the laminated film 14 including the first wavelength-selective reflective film 13a, the second wavelength-selective reflective film 13b, and the third wavelength-selective reflective film 13 is not limited to the embodiment shown in FIG. It may be in direct contact with the ⁇ / 4 plate 12 without going through.
  • the optical film has layers other than the first wavelength-selective reflective film 13a, the second wavelength-selective reflective film 13b, the third wavelength-selective reflective film 13c, and the ⁇ / 4 plate 12. Also good.
  • the ⁇ / 4 plate may be provided according to use conditions.
  • the polarization of incident light is random or circularly polarized in a reflective direction, the ⁇ / 4 plate is not necessary.
  • the film thickness of the optical film of the present invention is preferably 3 to 120 ⁇ m, more preferably 5 to 100 ⁇ m, and particularly preferably 6 to 90 ⁇ m.
  • the manufacturing method of the wavelength selective reflection film of the present invention includes an optical film forming process for forming an optical film in which a discotic liquid crystal compound is fixed in a cholesteric phase state, and a stretching process for biaxially stretching the optical film.
  • FIG. 4 the process in embodiment of the manufacturing method of a wavelength selective reflection film is shown.
  • steps (1) to (3) are optical film forming steps.
  • This optical film corresponds to a conventional reflective polarizer, and the formation method is not particularly limited, and a known method can be used.
  • JP-A-1-133003, JP-A-3416302, The methods described in Japanese Patent No. 3363565 and JP-A-8-271731 can be used.
  • a polymerizable liquid crystal composition containing a discotic liquid crystal compound is applied to the surface of the support to form a coating film.
  • the polymerizable liquid crystal composition is preferably prepared as a coating solution in which a material is dissolved and / or dispersed in a solvent.
  • the coating liquid can be applied by various methods such as a wire bar coating method, an extrusion coating method, a direct gravure coating method, a reverse gravure coating method, and a die coating method.
  • a liquid crystal composition can be discharged from a nozzle using an ink jet apparatus to form a coating film.
  • the discotic liquid crystal compound in the polymerizable liquid crystal composition constituting the coating film is brought into a cholesteric phase state.
  • the temperature is maintained at a temperature 1 to 15 ° C. lower than the phase transition temperature T ⁇ between the cholesteric phase and the isotropic phase (hereinafter, referred to as “ripening temperature”) within the orientation temperature range of the cholesteric phase.
  • aging temperature is required to be 1 °C is lower than the phase transition temperature T alpha, preferably a phase transition temperature T it is preferable close to the alpha, the phase transition temperature T 1 ⁇ 10 ° C. lower temperature than alpha, 1 ⁇ More preferably, the temperature is 5 ° C lower.
  • it is preferable to once heat to an isotropic phase temperature (a temperature sufficiently higher than T ⁇ , for example, T ⁇ + 10 ° C.) and then cool to the aging temperature and maintain for a certain period of time.
  • the certain time may be a period necessary for stabilizing the orientation state of the cholesteric phase. For example, 10 minutes or less is preferable in terms of productivity, 5 minutes or less is more preferable, and 3 minutes or less is more preferable. .
  • the aging temperature is to be set appropriately according to the polymerizable liquid crystal composition.
  • the orientation temperature range of the cholesteric phase is 80 ° C. to 110 ° C.
  • the phase transition temperature T ⁇ of the polymerizable liquid crystal composition is 110 ° C.
  • the phase transition temperature between the cholesteric phase and the non-cholesteric phase is 80 ° C.
  • the aging temperature is about 105 to 109 ° C.
  • the phase transition temperature T ⁇ between the isotropic phase and the liquid crystal phase of the polymerizable liquid crystal composition is preferably in the range of 10 to 250 ° C. from the viewpoint of production suitability and the like, and is in the range of 10 to 150 ° C. Is more preferable.
  • a cooling step or the like may be required to lower the temperature to a temperature range exhibiting a liquid crystal phase.
  • the heating temperature of a coating film shall be 200 degrees C or less from viewpoints, such as efficient utilization of a thermal energy, and the heat resistance of a board
  • the temperature at this time is the film surface temperature, and can be measured with PT-2LD manufactured by OPTEX.
  • the direction of rotation of the cholesteric phase can be adjusted by the type of liquid crystal used or the type of chiral agent added, and the helical pitch (ie, selective reflection wavelength) can be adjusted by the concentration of these materials.
  • the wavelength of a specific region reflected by each reflective polarizer can be shifted depending on various factors in the production method.
  • a discotic liquid crystal compound is mixed with a cholesteric phase. It can be shifted depending on conditions such as temperature, illuminance and irradiation time when fixing in a state.
  • the coating film in which the discotic liquid crystal compound is aligned in the state of cholesteric phase is irradiated with ultraviolet rays to advance the curing reaction, thereby obtaining an optical film.
  • a light source such as an ultraviolet lamp is used.
  • the curing reaction of the polymerizable liquid crystal composition proceeds and the cholesteric liquid crystal phase is fixed.
  • the amount of irradiation energy of ultraviolet rays is not particularly limited, but is generally preferably about 100 mJ / cm 2 to 800 mJ / cm 2 .
  • limiting in particular about the time which irradiates an ultraviolet-ray to a coating film What is necessary is just to determine from the viewpoint of both sufficient intensity
  • ultraviolet irradiation may be performed under heating conditions. Moreover, it is preferable to maintain the temperature at the time of ultraviolet irradiation at the above-mentioned ripening temperature so that the orientation state of the cholesteric phase is not disturbed. Also, since the oxygen concentration in the atmosphere is related to the degree of polymerization, if the desired degree of polymerization is not reached in the air and the film strength is insufficient, the oxygen concentration in the atmosphere is reduced by a method such as nitrogen substitution. It is preferable. A preferable oxygen concentration is preferably 10% or less, more preferably 7% or less, and most preferably 3% or less.
  • the reaction rate of the curing reaction (for example, polymerization reaction) that proceeds by irradiation with ultraviolet rays is 70% or more from the viewpoint of maintaining the mechanical strength of the layer and suppressing unreacted substances from flowing out of the layer.
  • it is 80% or more, more preferably 90% or more.
  • “fixing” the discotic liquid crystal compound in the cholesteric phase state is the most typical and preferred mode in which the orientation of the discotic liquid crystal compound in the cholesteric phase is not changed. Specifically, in a temperature range of 0 ° C. to 50 ° C., more severe conditions such as ⁇ 30 ° C. to 70 ° C., this layer has no fluidity, and the orientation form is changed by an external field or an external force. In other words, it means a state in which the fixed orientation form can be kept stable.
  • the orientation state of the cholesteric phase is preferably fixed by a curing reaction that proceeds by ultraviolet irradiation.
  • the liquid crystal composition may have a high molecular weight due to a curing reaction and may no longer have liquid crystallinity.
  • step (4) the optical film obtained in step (3) is biaxially stretched.
  • a known method can be used for biaxial stretching.
  • Each support on which the optical film is formed may be stretched longitudinally at a desired stretching ratio in a longitudinal uniaxial stretching machine and then stretched at a desired stretching ratio in a tenter stretching machine. Or you may extend
  • the biaxially stretched film may be made into a roll film by cutting off both ends before winding up and winding up at the winding up.
  • the intake air temperature, film film surface temperature, and stretching speed during stretching can be appropriately adjusted depending on the desired stretching ratio.
  • the draw ratio is not limited as long as a desired reflection wavelength band half-width can be obtained, but is preferably about 20% to 50%, more preferably 30% to 40%.
  • the stretching ratio in length and width is basically the same. However, the longitudinal and lateral draw ratios may be different as long as they do not affect the optical characteristics, and a difference of about 5% is allowed.
  • the film surface temperature during stretching is preferably the glass transition point Tg ⁇ 40 ° C. to Tg + 20 ° C., more preferably Tg ⁇ 20 ° C. to Tg + 10 ° C. of the support on which the cholesteric liquid crystal phase is formed.
  • the steps (1) to (3) are repeated to form a laminate film of a plurality of optical films, and then according to the step (4). What is necessary is just to extend
  • the discotic liquid crystal compound, the other components and the solvent which are components of the polymerizable liquid crystal composition used for the production of the wavelength selective reflection film, will be described.
  • the discotic liquid crystal compound that is a material of the wavelength selective reflection film will be described.
  • the discotic liquid crystal compound for example, those described in JP2007-108732A and JP2010-244038A can be preferably used.
  • the composition used for forming the wavelength-selective reflective film contains other components such as a chiral agent, an alignment controller, a polymerization initiator, and an alignment aid in addition to the above-mentioned discotic liquid crystal compound. Also good. Any known material can be used.
  • organic solvent As a solvent of the composition for forming each reflective polarizer, an organic solvent is preferably used.
  • organic solvents include amides (eg N, N-dimethylformamide), sulfoxides (eg dimethyl sulfoxide), heterocyclic compounds (eg pyridine), hydrocarbons (eg benzene, hexane), alkyl halides (eg , Chloroform, dichloromethane), esters (eg, methyl acetate, butyl acetate), ketones (eg, acetone, methyl ethyl ketone, cyclohexanone), ethers (eg, tetrahydrofuran, 1,2-dimethoxyethane). Alkyl halides and ketones are preferred. Two or more organic solvents may be used in combination.
  • a transparent support is preferable, a polyacrylic resin film such as polymethyl methacrylate, a cellulose resin film such as cellulose triacetate, and a cycloolefin polymer film [for example, trade name “ARTON”, manufactured by JSR Corporation, Trade name “Zeonoa”, manufactured by Nippon Zeon Co., Ltd.].
  • the wavelength-selective reflecting film of the present invention may be used while being supported by a support when forming a film, or the support when forming a film is a temporary support, It may be transferred onto another layer such as a support or a ⁇ / 4 plate and used by peeling the temporary support.
  • a temporary support is not particularly limited, but preferably has physical properties that can withstand stretching and peeling in the production process.
  • the alignment layer can be provided by means such as a rubbing treatment of an organic compound (preferably a polymer), oblique vapor deposition of an inorganic compound, or formation of a layer having a microgroove. Furthermore, an alignment layer in which an alignment function is generated by application of an electric field, application of a magnetic field, or light irradiation is also known.
  • the alignment layer is preferably formed by rubbing the surface of the polymer film.
  • the alignment layer is preferably peeled off together with the support.
  • the support can function as an orientation layer by directly subjecting the support to an orientation treatment (for example, rubbing treatment) without providing an orientation layer.
  • an orientation treatment for example, rubbing treatment
  • An example of such a support is PET (polyethylene terephthalate).
  • the ⁇ / 4 plate is a layer for converting circularly polarized light into linearly polarized light and linearly polarized light into circularly polarized light. It is arranged on the light incident surface side of the wavelength selective reflection film, converts linearly polarized light into circularly polarized light and makes it incident as circularly polarized light reflected by the wavelength selective reflective film, and converts the reflected circularly polarized light into linearly polarized light. Exit. Thereby, the reflection efficiency in the wavelength selective reflection film when specific linearly polarized light is incident on the optical film can be improved. Note that the ⁇ / 4 plate is designed to convert linearly polarized light into circularly polarized light in the direction reflected by the wavelength selective reflection film.
  • the ⁇ / 4 plate may be an optically anisotropic support having a ⁇ / 4 function, or may have an optically anisotropic layer or the like on a support made of a polymer film. .
  • ⁇ Adhesive layer (adhesive layer)>
  • “adhesion” is used in a concept including “adhesion”.
  • the ⁇ / 4 plate and the wavelength selective reflection film are laminated in direct contact or via an adhesive layer.
  • the wavelength-selective reflective film is not only in a form of being directly contacted and laminated, but may be laminated via an adhesive layer between the reflective films. Good.
  • the pressure-sensitive adhesive used for the adhesive layer examples include resins such as polyester resins, epoxy resins, polyurethane resins, silicone resins, and acrylic resins. You may use these individually or in mixture of 2 or more types.
  • an acrylic resin is preferable because it is excellent in reliability such as water resistance, heat resistance, and light resistance, has good adhesion and transparency, and can easily adjust the refractive index to be compatible with a liquid crystal display.
  • a sheet-like photo-curing adhesive (Toagosei Group Research Annual Report 11 TREND 2011 No. 14) can also be used for the adhesive layer. Bonding between optical films is easy, like an adhesive, crosslinks and cures with ultraviolet rays (UV), improves storage elastic modulus, adhesive strength and heat resistance, and is an adhesive method suitable for the present invention. .
  • UV ultraviolet rays
  • FIG. 5 is a schematic diagram showing a schematic configuration of an embodiment of the image display device of the present invention.
  • the image display device 100 includes a light-transmissive screen 101, an optical film 11 including a wavelength-selective reflective film attached to the surface of the screen 101, and the optical film 11. And a liquid crystal projector 102 that projects an image on a screen 101 to which is attached.
  • the optical film 11 is formed by laminating the laminated film 14 of the first to third wavelength selective reflecting films having the reflection wavelength regions having the different reflection center wavelengths and the ⁇ / 4 plate 12 with the adhesive layer 20 interposed therebetween. It will be.
  • the first to third wavelength selective reflection films are formed so that the reflection center wavelength thereof substantially coincides with the blue, green, and red peak wavelengths of light output from the liquid crystal projector 102.
  • the first wavelength-selective reflective film is a blue reflective layer
  • the second wavelength-selective reflective film is a green reflective layer
  • the third wavelength-selective reflective film is a red reflective layer.
  • the first to third wavelength selective reflection films may be laminated in any order.
  • the first to third wavelength selective reflection films are configured to selectively reflect circularly polarized light in the same predetermined direction, for example, right circularly polarized light.
  • the light carrying the image output from the liquid crystal projector 102 (hereinafter, image carrying light) is linearly polarized light.
  • This linearly polarized light enters the ⁇ / 4 plate 12 of the optical film 11, is converted into circularly polarized light in a predetermined direction, for example, right circularly polarized light, and enters the laminated film 14 of the wavelength selective reflection film.
  • the right-circularly polarized image-bearing light incident on the laminated film 14 reflects blue light at the first wavelength-selective reflective film, reflects green light at the second wavelength-selective reflective film, and selects the third wavelength-selective light.
  • the red light is reflected by the conductive reflective film, converted into linearly polarized light by the ⁇ / 4 plate 12 and output.
  • the blue, green, and red peak wavelengths of light output from the liquid crystal projector 102 and the reflection center wavelengths of the first to third wavelength selective reflection films are in a range of about ⁇ 10 nm. Since the image-bearing light output from the liquid crystal projector 102 can be reflected efficiently, the projected image can be displayed clearly.
  • the first to third wavelength-selective reflective films having a reflection wavelength band that matches the output wavelength of the image projection apparatus and each reflection wavelength half-value width of 40 nm or less are very narrow bands.
  • the first to third three-layer wavelength-selective reflection films are provided.
  • the light output from the liquid crystal projector is monochromatic and the image is displayed on the screen in monochromatic, It is only necessary to provide one wavelength selective reflection film.
  • the screen can be, for example, an automobile windshield or eyeglass lens, and a head-up display, a head-mounted display, or the like can be configured as an image display device with high external light transmittance.
  • R 1 is a hydrogen atom
  • R 2 and R 3 are methyl groups.
  • An alignment layer coating solution (A) having the following composition was continuously applied to the temporary support with a # 14 wire bar. Drying was performed with warm air of 60 ° C. for 60 seconds, and further with warm air of 100 ° C. for 120 seconds. The degree of saponification of the modified polyvinyl alcohol used was 96.8%.
  • composition of coating liquid for alignment layer (A)- Denatured polyvinyl alcohol 10 parts by weight Water 308 parts by weight Methanol 70 parts by weight Isopropanol 29 parts by weight Photopolymerization initiator (IRGACURE (registered trademark) 2959, manufactured by BASF) 0.8 parts by mass
  • composition ratio of the modified polyvinyl alcohol is a molar fraction.
  • the rubbing treatment was continuously performed on the prepared alignment layer. At this time, the longitudinal direction of the long film and the transport direction were parallel, and the angle formed by the longitudinal direction of the film and the rotation axis of the rubbing roller was about 45 °.
  • the discotic liquid crystal compounds 101 and 102 were used to form an optical film in which the discotic liquid crystal compound was fixed in a cholesteric phase state.
  • Concentrate the components of the following coating solution for forming an optical film so that the dry film thickness after stretching is 3.5 ⁇ m and dissolve in MEK (methyl ethyl ketone).
  • MEK methyl ethyl ketone
  • This coating solution was applied onto the above alignment layer with a bar and subjected to heat aging at 110 ° C. for 3 minutes to obtain a uniform alignment state of the cholesteric phase. Thereafter, this coating film was kept at 45 ° C., and irradiated with 300 mJ / cm 2 ultraviolet rays using a metal halide lamp to form an optical film.
  • the film on which the optical film was formed as described above was subjected to a draw ratio shown in Table 1 at a supply air temperature of 150 ° C., a film film surface temperature of 140 ° C., and a draw rate of 30% / min. 23%). Then, in a tenter type stretching machine, the film was horizontally stretched at the same draw ratio (23%) as the longitudinal stretching at an air supply temperature of 150 ° C., a film film surface temperature of 140 ° C., and a stretching speed of 30% / min.
  • the optical film provided with the wavelength-selective reflecting film of Example 1 was obtained by cutting off the part and winding it as a 4000 m long roll film and biaxially stretching it.
  • Example 2 The wavelength-selective reflective film was the same as in Example 1 except that the aging temperature and the draw ratio were as shown in Table 1, and the addition amount of the chiral agent was adjusted so that the reflection center wavelength after stretching was 550 nm. Was made.
  • the aging temperature was 85 ° C.
  • Comparative Example 1 The optical film provided with the optical film before stretching in Example 1 was defined as Comparative Example 1.
  • Example 2 an optical film was produced in the same manner as in Example 1 except that the addition amount of the chiral agent was adjusted so that the reflection center wavelength in the optical film before stretching was 550 nm. In this comparative example, stretching is not performed.
  • the obtained optical film was stretched at a magnification of 23% using the same stretching method as in Example 1.
  • the retardation Rth in the thickness direction of the wavelength-selective reflective films of Examples and Comparative Examples was measured using Axoscan from Axometrics. As described above, the wavelength-selective reflective film was bonded to a glass plate with an acrylic adhesive, and the measurement was performed in a state where the temporary support was peeled off. A wavelength of 650 nm, which is the reflection center wavelength (550 nm) +100 nm shown in Table 1, was used as measurement light. Rth was measured when light having a wavelength of 650 nm was incident on the film surface of the wavelength selective reflection film from the normal direction. The measuring method is as described above. Since Rth of glass and acrylic adhesive is almost 0, the measurement result can be regarded as a characteristic of the wavelength selective reflection film.
  • Table 1 shows the results of measuring the production conditions, the thickness direction retardation Rth, the reflection center wavelength, and the reflection half-value width for the examples and comparative examples.
  • DLC means a disk-like liquid crystal
  • CLC means a rod-like liquid crystal.
  • the wavelength-selective reflective films of Examples 1 to 7 have remarkably small reflection half-value widths as compared with the optical films that are not stretched as in Comparative Examples 1 and 2. From Examples 1 to 6 in which only the draw ratio was changed at the same ripening temperature, in the case of an optical film obtained by ripening the same composition at the same ripening temperature, the larger the draw ratio, the smaller the reflection half width, It is clear that Rth shifts to the positive side compared to before stretching. When the ripening temperature was low as in Example 7, the reflection half-value width was increased as compared with Example 4 having the same draw ratio. This is considered to be due to the fact that the orientation state differs depending on the aging temperature.
  • Comparative Example 3 has a cholesteric phase of a rod-like liquid crystal compound, and Rth has a positive value in the optical film before stretching, and the value of Rth does not change greatly even after stretching.
  • the reflection half width was 60 nm even when stretched, and a sufficiently small reflection half width was not obtained.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Nonlinear Science (AREA)
  • Mathematical Physics (AREA)
  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Polarising Elements (AREA)
  • Projection Apparatus (AREA)
  • Instrument Panels (AREA)
  • Overhead Projectors And Projection Screens (AREA)
  • Optical Filters (AREA)

Abstract

La présente invention concerne une membrane de réflexion sélective en longueur d'onde qui est une membrane optique à étirement biaxial dans laquelle un composé de cristaux liquides discotiques est fixé dans un état de phase cholestérique, la largeur de demi-valeur de sa région de longueur d'onde de réflexion étant de 40 nm ou moins.
PCT/JP2017/025179 2016-07-15 2017-07-10 Membrane de réflexion sélective en longueur d'onde, film optique, procédé de fabrication d'une membrane de réflexion sélective en longueur d'onde, et dispositif d'affichage d'image Ceased WO2018012469A1 (fr)

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WO2019146423A1 (fr) * 2018-01-25 2019-08-01 富士フイルム株式会社 Élément d'affichage d'image projetée, vitre de pare-brise, et système d'affichage tête haute
WO2020071169A1 (fr) * 2018-10-01 2020-04-09 富士フイルム株式会社 Dispositif d'affichage
GB2579370A (en) * 2018-11-29 2020-06-24 Bae Systems Plc Display device
WO2021060407A1 (fr) * 2019-09-27 2021-04-01 富士フイルム株式会社 Élément pour affichage d'image projetée, verre de pare-brise, et système d'affichage tête haute
WO2024195716A1 (fr) * 2023-03-20 2024-09-26 富士フイルム株式会社 Film réfléchissant, verre de pare-brise et système d'affichage tête haute
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JPWO2019146423A1 (ja) * 2018-01-25 2021-01-07 富士フイルム株式会社 投映像表示用部材、ウインドシールドガラスおよびヘッドアップディスプレイシステム
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WO2025180177A1 (fr) * 2024-03-01 2025-09-04 华为技术有限公司 Film réfléchissant, élément pliable, module de caméra et dispositif électronique

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