WO2021200433A1 - 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 - Google Patents

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 Download PDF

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Publication number
WO2021200433A1
WO2021200433A1 PCT/JP2021/012159 JP2021012159W WO2021200433A1 WO 2021200433 A1 WO2021200433 A1 WO 2021200433A1 JP 2021012159 W JP2021012159 W JP 2021012159W WO 2021200433 A1 WO2021200433 A1 WO 2021200433A1
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WIPO (PCT)
Prior art keywords
layer
liquid crystal
glass
cholesteric liquid
light
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Ceased
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PCT/JP2021/012159
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English (en)
French (fr)
Japanese (ja)
Inventor
昭裕 安西
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Fujifilm Corp
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Fujifilm Corp
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Priority to JP2022512008A priority Critical patent/JP7260715B2/ja
Publication of WO2021200433A1 publication Critical patent/WO2021200433A1/ja
Anticipated expiration legal-status Critical
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60K—ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
    • B60K35/00—Instruments specially adapted for vehicles; Arrangement of instruments in or on vehicles
    • B60K35/20—Output arrangements, i.e. from vehicle to user, associated with vehicle functions or specially adapted therefor
    • B60K35/28—Output arrangements, i.e. from vehicle to user, associated with vehicle functions or specially adapted therefor characterised by the type of the output information, e.g. video entertainment or vehicle dynamics information; characterised by the purpose of the output information, e.g. for attracting the attention of the driver
    • 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
    • B32B17/00—Layered products essentially comprising sheet glass, or glass, slag, or like fibres
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60J—WINDOWS, WINDSCREENS, NON-FIXED ROOFS, DOORS, OR SIMILAR DEVICES FOR VEHICLES; REMOVABLE EXTERNAL PROTECTIVE COVERINGS SPECIALLY ADAPTED FOR VEHICLES
    • B60J1/00—Windows; Windscreens; Accessories therefor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60J—WINDOWS, WINDSCREENS, NON-FIXED ROOFS, DOORS, OR SIMILAR DEVICES FOR VEHICLES; REMOVABLE EXTERNAL PROTECTIVE COVERINGS SPECIALLY ADAPTED FOR VEHICLES
    • B60J1/00—Windows; Windscreens; Accessories therefor
    • B60J1/02—Windows; Windscreens; Accessories therefor arranged at the vehicle front, e.g. structure of the glazing, mounting of the glazing
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60K—ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
    • B60K35/00—Instruments specially adapted for vehicles; Arrangement of instruments in or on vehicles
    • B60K35/20—Output arrangements, i.e. from vehicle to user, associated with vehicle functions or specially adapted therefor
    • B60K35/21—Output arrangements, i.e. from vehicle to user, associated with vehicle functions or specially adapted therefor using visual output, e.g. blinking lights or matrix displays
    • B60K35/22—Display screens
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60K—ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
    • B60K35/00—Instruments specially adapted for vehicles; Arrangement of instruments in or on vehicles
    • B60K35/20—Output arrangements, i.e. from vehicle to user, associated with vehicle functions or specially adapted therefor
    • B60K35/21—Output arrangements, i.e. from vehicle to user, associated with vehicle functions or specially adapted therefor using visual output, e.g. blinking lights or matrix displays
    • B60K35/23—Head-up displays [HUD]
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60K—ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
    • B60K35/00—Instruments specially adapted for vehicles; Arrangement of instruments in or on vehicles
    • B60K35/60—Instruments characterised by their location or relative disposition in or on vehicles
    • 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
    • G02B27/01—Head-up displays
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements

Definitions

  • the present invention relates to a windshield glass and a head-up display system using this windshield glass.
  • head-up display head-up display system
  • the head-up display system is also referred to as "HUD”.
  • HUD is an abbreviation for "Head up Display”.
  • the driver can obtain various information such as a map, a running speed, and the state of the vehicle while looking at the outside world in front of the driver without moving his / her line of sight significantly. Therefore, by using the HUD, the driver can be expected to drive more safely while obtaining various information.
  • the highest reflectance is obtained when s-polarized light is incident at Brewster's angle.
  • the projected light of s-polarized light is usually projected from the projector, and the projected light of s-polarized light is incident on the windshield glass at an angle close to Brewster's angle and reflected. Project the image.
  • the driver often wears sunglasses when driving.
  • sunglasses polarized sunglasses that suppress glare caused by reflected light such as a puddle on the road and light that hinders operation such as glare caused by reflected light from the bonnet are known.
  • the glaring light that the driver feels dazzling, such as glaring due to reflected light from a puddle on the road is s-polarized light. Therefore, polarized sunglasses are usually made to block s-polarized light.
  • most of the projected light of the HUD is s-polarized light. Therefore, in a normal HUD, when the driver wears polarized sunglasses, the projected image cannot be observed.
  • a HUD using a half mirror film that reflects p-polarized light has also been proposed.
  • the projected light of p-polarized light is projected from the projector, and the projected light of p-polarized light is reflected by the half mirror film incorporated in the windshield glass to display the projected image.
  • Patent Document 1 includes a non-reflective region, a reflective region composed of a cholesteric liquid crystal layer having a cholesteric liquid crystal phase fixed, and a non-reflective portion and a cholesteric liquid crystal layer between the non-reflective region and the reflective region.
  • Patent Document 1 describes a windshield glass in which this half mirror film is used and laminated in the order of inner surface side glass / intermediate film / half mirror film / intermediate film / outer surface side crow.
  • the half mirror film is formed by laminating a ⁇ / 2 plate and a cholesteric liquid crystal layer (reflection layer) from the inner glass side.
  • the projected light of p-polarized light is incident on the above-mentioned windshield glass at a Brewster's angle.
  • the ⁇ / 2 plate acts as a ⁇ / 2 plate when light is incident from the normal direction, but acts as a ⁇ / 4 plate when light is incident at Brewster's angle. Therefore, the p-polarized light is incident on the ⁇ / 2 plate, converted into circularly polarized light, and incident on the cholesteric liquid crystal layer.
  • the cholesteric liquid crystal layer reflects the circularly polarized light in a predetermined turning direction in a wavelength-selective manner.
  • the projected light converted to circularly polarized light by the ⁇ / 2 plate is incident on the cholesteric liquid crystal layer, reflected, and then incident on the ⁇ / 2 plate again.
  • the circularly polarized light incident on the ⁇ / 2 plate is returned to p-polarized light, and the projected light of p-polarized light is applied to the observation position of the projected image by the driver.
  • the projected light of p-polarized light is irradiated to the observation position of the projected image by the driver. Therefore, according to this HUD, even when the driver wears polarized sunglasses that block s-polarized light, the projected image can be observed.
  • the reflected light due to the bonnet, the puddle on the road surface, or the like, which hinders the operation is mainly s-polarized light.
  • polarized sunglasses block s-polarized light.
  • the s-polarized light that has entered from the outside of the windshield glass changes the polarization of the light when it passes through the cholesteric liquid crystal layer (half mirror film) in the windshield glass, and the p-polarized light component is mixed. It ends up. Since polarized sunglasses block s-polarized light, this p-polarized component passes through the polarized sunglasses. Therefore, in the HUD that displays the projected image with p-polarized light, there is a problem that the function of the polarized sunglasses that shields the reflected light that becomes glare incident from the outside of the vehicle is impaired, which hinders driving.
  • An object of the present invention is to solve such a problem of the prior art, which is a windshield glass used for HUD or the like, capable of irradiating a projected image with p-polarized light, and incident from outside the vehicle. It is an object of the present invention to provide a windshield glass having excellent suitability for polarized sunglasses against external light, which does not impair the function of polarized sunglasses that block external light of polarized light, and a HUD using this windshield glass.
  • the present invention has the following configuration.
  • the first curved glass, the polarization conversion layer in which the spiral orientation structure of the liquid crystal compound is fixed, the cholesteric liquid crystal layer in which the cholesteric liquid crystal phase is fixed, and the concave surface are arranged toward the first curved glass.
  • Has a second curved glass A polarization conversion layer, a cholesteric liquid crystal layer, and a second curved glass are provided on the convex side of the first curved glass in this order.
  • a retardation layer is provided between the cholesteric liquid crystal layer and the second curved glass.
  • the retardation layer has a front retardation of 50 to 170 nm at a wavelength of 550 nm, and when the direction corresponding to the vertical direction upward of the first curved glass surface when the windshield glass is mounted on the vehicle is set to 0 °.
  • the head-up display system according to [9] wherein the projector irradiates the projected light of p-polarized light.
  • polarized sunglasses for external light can be projected (displayed) by p-polarized light, and the function of polarized sunglasses that shields s-polarized external light incident from the outside of the vehicle is not impaired.
  • a windshield glass having excellent suitability and a HUD using this windshield glass are provided.
  • visible light is light having a wavelength visible to the human eye among electromagnetic waves, and indicates light in the wavelength range of 380 to 780 nm.
  • Invisible light is light in a wavelength region of less than 380 nm or in a wavelength region of more than 780 nm.
  • the light in the wavelength range of 420 to 490 nm is blue light (B light)
  • the light in the wavelength range of 495 to 570 nm is green light (G light).
  • the light in the wavelength range of 620 to 750 nm is red light (R light).
  • ultraviolet light refers to light in the wavelength range of 100 to 380 nm among invisible light.
  • s-polarized light means polarized light that oscillates in a direction orthogonal to the incident surface of light
  • p-polarized light means polarized light that oscillates in a direction parallel to the incident surface of light.
  • the incident surface is perpendicular to the reflecting surface and means a surface containing the incident light rays and the reflected rays.
  • the vibration plane of the electric field vector is perpendicular to the entrance plane
  • p-polarization the vibration plane of the electric field vector is parallel to the entrance plane.
  • the term “selective” when used for circularly polarized light, it means that the amount of light of either the right-handed circularly polarized light component or the left-handed circularly polarized light component of light is larger than that of the other circularly polarized light component.
  • the degree of circular polarization of light is preferably 0.3 or more, more preferably 0.6 or more, and even more preferably 0.8 or more.
  • the circular polarization degree of light is particularly preferably 1.0.
  • sense for circularly polarized light, it means whether it is right-handed circularly polarized light or left-handed circularly polarized light.
  • the sense of circularly polarized light is right-handed circularly polarized light when the tip of the electric field vector turns clockwise as time increases when viewed as the light travels toward you, and left when it turns counterclockwise. Defined as circularly polarized light.
  • sense is sometimes used for the twisting direction of the spiral of the cholesteric liquid crystal.
  • twist direction (sense) of the spiral of the cholesteric liquid crystal When the twist direction (sense) of the spiral of the cholesteric liquid crystal is right, it reflects right circularly polarized light and transmits left circularly polarized light, and when the sense is left, it reflects left circularly polarized light and transmits right circularly polarized light.
  • the front retardation is a value measured using AxoScan manufactured by Axometrics.
  • the measurement wavelength is 550 nm.
  • a value measured by KOBRA 21ADH or WR manufactured by Oji Measuring Instruments Co., Ltd.
  • the wavelength selection filter can be replaced manually, or the measured value can be converted by a program or the like for measurement.
  • the "projection image” means an image based on the projection of light from a projector to be used, not the surrounding landscape such as the front.
  • the projected image is observed as a virtual image that appears to emerge beyond the projected image display portion of the windshield glass when viewed from the observer.
  • the “screen image” means an image displayed on a drawing device of a projector or an image drawn on an intermediate image screen or the like by the drawing device. In contrast to a virtual image, the image is a real image.
  • the "visible light transmittance” is the A light source visible light transmittance defined in JIS R 3212: 2015 (safety glass test method for automobiles). That is, for the visible light transmittance, the transmittance of each wavelength in the range of 380 to 780 nm is measured with a spectrophotometer using an A light source, and the wavelength distribution of the CIE (International Lighting Commission) light adaptation standard relative luminous efficiency. And the transmittance obtained by multiplying the transmittance at each wavelength and weight averaging the weight coefficient obtained from the wavelength interval.
  • CIE International Lighting Commission
  • the windshield glass of the present invention is a windshield glass used for vehicles and the like, and is generally used as a windshield for vehicles such as cars and trains, aircraft, ships, two-wheeled vehicles, and vehicles such as play equipment.
  • the terms “outside and inside” refer to the outside and inside of an aircraft, and the outside and inside of a ship.
  • the expression “mounted on the vehicle” is similar.
  • the projected light is projected from the inside of the vehicle toward the windshield glass.
  • FIG. 1 conceptually shows an example of the windshield glass of the present invention.
  • the figures shown below are conceptual diagrams for explaining the present invention. Therefore, the thickness, size, shape, positional relationship, etc. of each layer and each member do not always match the actual ones.
  • the windshield glass 10 shown in FIG. 1 has an interlayer film 16, a polarization conversion layer 24, a reflective layer 18, a retardation layer 28, and a transparent base material 26 between the first glass 12 and the second glass 14. And a heat-sealing layer 20.
  • the reflective layer 18 has a cholesteric liquid crystal layer. In the illustrated example, the reflective layer 18 has a green-blue reflective cholesteric liquid crystal layer 18GB and a red reflective cholesteric liquid crystal layer 18R as the cholesteric liquid crystal layer.
  • the first glass 12 is the first curved glass in the present invention.
  • the second glass 14 is the second curved glass in the present invention.
  • the second glass 14 is arranged with the concave surface facing the convex surface of the first glass 12.
  • the interlayer film 16, the polarization conversion layer 24, the reflection layer 18, the retardation layer 28, the transparent base material 26, the heat seal layer 20, and the heat seal layer 20 are formed on the convex side of the first glass 12.
  • the second glass 14 is arranged in this order.
  • the polarization conversion layer 24, the reflection layer 18, and the retardation layer 28 constitute a half mirror film with a transparent base material 26.
  • the 12th side of the first glass is also referred to as "lower” and the 14th side of the second glass is also referred to as "upper".
  • the interlayer film 16, the retardation layer 28, the transparent base material 26, and the heat seal layer 20 are provided as preferred embodiments and are not essential constituent requirements. That is, the windshield glass of the present invention has at least the first glass 12, the polarization conversion layer 24, the reflection layer 18, and the second glass 14, and the polarization conversion layer is on the convex side of the first glass 12. 24, the reflective layer 18 and the second glass 14 may be provided in this order. In this configuration, the polarization conversion layer 24 and the reflection layer 18 form a half mirror film. Therefore, the windshield glass of the present invention may be composed of only the first glass 12, the polarization conversion layer 24, the reflective layer 18 and the second glass 14, or in addition to these, the interlayer film 16 and the retardation layer.
  • one or more of the transparent base material 26 and the heat seal layer 20 may be appropriately provided. Which of the interlayer film 16, the retardation layer 28, the transparent base material 26, and the heat seal layer 20 is added is appropriately selected according to the application of the windshield glass, the required performance, the layer structure, and the like. Just do it.
  • the first glass 12 is the first curved glass in the present invention.
  • the second glass is the second curved glass in the present invention.
  • the windshield glass 10 of the present invention which is a laminated glass using the first glass 12 and the second glass 14 which are curved glass, is a laminated glass having a curved surface.
  • the interlayer film 16, the polarization conversion layer 24, the reflective layer 18, the retardation layer 28, the transparent base material 26, and the heat seal layer 20 are formed on the convex side of the first glass 12.
  • the second glass 14 are arranged in this order.
  • the concave side of the curved surface is the inner surface of the vehicle.
  • the concave surface of the first glass 12 is the inner surface of the vehicle, and the convex surface of the second glass 14 is the outer surface of the vehicle.
  • the projected light of the HUD which will be described later, is emitted from the concave side of the first glass 12.
  • the shapes of the first glass 12 and the second glass 14 are not limited, and any curved glass (glass plate having a curved surface) can be used as a windshield glass depending on the vehicle to be mounted.
  • the shape is available. Therefore, the first glass 12 and the second glass 14 may have a curved surface on the entire surface or a mixture of a curved surface and a flat surface. Further, the curved surfaces of the first glass 12 and the second glass 14 may have the same curvature on the entire surface or may be a mixture of curved surfaces having different curvatures.
  • a glass plate generally used for windshield glass can be used.
  • a glass plate having a visible light transmittance of 73%, 76%, etc., which is 80% or less, such as green glass having a high heat-shielding property is exemplified.
  • the thickness of the first glass 12 and the second glass 14 is not limited, and a thickness capable of obtaining sufficient strength may be appropriately set according to the forming material and shape of the glass plate.
  • the thickness of the first glass 12 and the second glass 14 is preferably 0.5 to 5.0 mm, more preferably 1.0 to 3.0 mm, and even more preferably 2.0 to 2.3 mm.
  • the materials and / or thicknesses of the first glass 12 and the second glass 14 may be the same or different.
  • An interlayer film 16 is provided on the convex surface of the first glass 12. As described above, the interlayer film 16 is provided as a preferred embodiment, and is provided between the first glass 12 and the polarization conversion layer 24.
  • the interlayer film 16 is a known interlayer film used for laminated glass used as a windshield glass. Therefore, the interlayer film 16 adheres the first glass 12 and the polarization conversion layer 24 described later, and when an impact is received such as in the event of an accident, the glass is scattered in the vehicle and the window. It has a function of ensuring impact resistance, which prevents an object having an impact on the shield glass 10 from entering the vehicle.
  • interlayer film 16 various known interlayer films used for laminated glass used as windshield glass can be used.
  • a resin film containing a resin such as polyvinyl butyral (PVB), ethylene-vinyl acetate copolymer, and chlorine-containing resin can be used.
  • the above-mentioned resin is preferably the main component of the interlayer film 16.
  • the main component means the component having the largest amount among the components forming the substance, and preferably the component accounting for 50% by mass or more.
  • polyvinyl butyral and ethylene-vinyl acetate copolymer are preferably exemplified, and polyvinyl butyral is more preferably exemplified.
  • the resin is preferably a synthetic resin.
  • Polyvinyl butyral can be obtained by acetalizing polyvinyl alcohol with butyraldehyde.
  • the preferred lower limit of the degree of acetalization of polyvinyl butyral described above is 40%, the preferred upper limit is 85%, the more preferred lower limit is 60%, and the more preferred upper limit is 75%.
  • Polyvinyl alcohol is usually obtained by saponifying polyvinyl acetate, and polyvinyl alcohol having a saponification degree of 80 to 99.8 mol% is generally used. Further, the preferable lower limit of the degree of polymerization of the above-mentioned polyvinyl alcohol is 200, and the preferable upper limit is 3000. When the degree of polymerization of polyvinyl alcohol is 200 or more, the penetration resistance of the obtained laminated glass is unlikely to decrease, and when it is 3000 or less, the moldability of the resin film is good and the rigidity of the resin film does not become too large. Good workability. A more preferred lower limit is 500 and a more preferred upper limit is 2000.
  • the thickness of the interlayer film 16 is not limited.
  • the thickness of the interlayer film 16 may be appropriately set to a thickness at which the desired impact resistance and adhesive force can be obtained, depending on the forming material and the like.
  • the thickness of the interlayer film 16 is preferably 380 to 1500 ⁇ m. By setting the thickness of the interlayer film 16 to 380 ⁇ m or more, sufficient impact resistance can be obtained, sufficient adhesion between the first glass 12 and the polarization conversion layer 24 can be obtained, and sufficient ultraviolet light shielding property inside the vehicle can be obtained. It is preferable in that it can be obtained in the above.
  • the windshield glass 10 By setting the thickness of the interlayer film 16 to 1500 ⁇ m or less, the windshield glass 10 can be made thinner, and the weight of the windshield glass can be reduced, which is preferable.
  • the thickness of the interlayer film 16 is more preferably 500 to 1140 ⁇ m, still more preferably 700 to 800 ⁇ m.
  • a polarization conversion layer 24 is provided on the interlayer film 16, that is, between the interlayer film 16 and the reflective layer 18.
  • the polarization conversion layer 24 is a layer in which the spiral orientation structure of the liquid crystal compound is immobilized.
  • the polarization conversion layer 24 converts p-polarized light (linearly polarized light) incident from the first glass 12 side inside the vehicle into circularly polarized light. Further, the polarization conversion layer 24 converts the circularly polarized light reflected by the reflection layer 18 (cholesteric liquid crystal layer) into p-polarized light.
  • the windshield glass 10 of the present invention makes it possible to project a projected image by p-polarization with high brightness.
  • the polarization conversion layer 24 will be described in detail later.
  • a reflection layer 18 is provided on the polarization conversion layer 24.
  • the reflective layer 18 has a cholesteric liquid crystal layer in which the cholesteric liquid crystal phase is fixed. Therefore, the reflective layer 18 selectively reflects light in a specific wavelength range.
  • the reflective layer 18, that is, the cholesteric liquid crystal layer may be provided corresponding to the entire surface of the first glass 12, or may be provided corresponding to a part of the first glass 12. ..
  • the reflective layer 18 is preferably provided so as to correspond to the entire surface of the first glass 12. The same applies to the polarization conversion layer 24 and the retardation layer 28 in this regard.
  • the reflective layer 18 of the illustrated example has a green-blue reflective cholesteric liquid crystal layer 18GB that selectively reflects green light and blue light, and a red reflective cholesteric liquid crystal layer 18R that selectively reflects red light.
  • the green-blue reflective cholesteric liquid crystal layer 18 GB and the red reflective cholesteric liquid crystal layer 18R are laminated in this order from the polarization conversion layer 24 side.
  • the windshield glass of the present invention is not limited to this, and various cholesteric liquid crystal layers and combinations of cholesteric liquid crystal layers can be used.
  • the windshield glass of the present invention may have only a green-blue reflective cholesteric liquid crystal layer of 18 GB.
  • the windshield glass of the present invention may have two layers, a red-green reflective cholesteric liquid crystal layer that selectively reflects red light and green light, and a blue reflective cholesteric liquid crystal layer that selectively reflects blue light. Often, it may have only a red-green reflective cholesteric liquid crystal layer. Further, the windshield glass of the present invention may have three cholesteric liquid crystal layers of a red reflective cholesteric liquid crystal layer, a green reflective cholesteric liquid crystal layer that selectively reflects green light, and a blue reflective cholesteric liquid crystal layer. ..
  • the windshield glass of the present invention may have only one of the red reflective cholesteric liquid crystal layer, the green reflective cholesteric liquid crystal layer, and the blue reflective cholesteric liquid crystal layer, or may be appropriately selected and combined. It may have two layers. Further, the windshield glass of the present invention may have a cholesteric liquid crystal layer that reflects all of blue light, green light and red light in one layer.
  • the center wavelength of selective reflection of the cholesteric liquid crystal layer shifts to the short wave side with respect to oblique light.
  • the shift of the center wavelength of the reflection to the short wave side is called a blue shift.
  • blue shift occurs in the cholesteric liquid crystal layer due to the small difference in optical path length between each layer due to optical interference. Therefore, when observed from an oblique direction, a blue shift occurs. Therefore, it is desirable that the cholesteric liquid crystal layer constituting the reflection layer 18 corrects in advance the amount by which the center wavelength of reflection shifts to the short wave side, and shifts the reflection center wavelength in front of the selective reflection layer to the long wave side.
  • the center wavelength can be shifted.
  • the wavelength range of the above-mentioned reflective layer 18 is set in consideration of the blue shift.
  • the cholesteric liquid crystal layer is a layer in which the cholesteric liquid crystal phase is fixed.
  • the cholesteric liquid crystal layer may be a layer in which the orientation of the liquid crystal compound in the cholesteric liquid crystal phase is maintained.
  • the cholesteric liquid crystal layer is typically a polymerized liquid crystal compound in an oriented state of the cholesteric liquid crystal phase, and then polymerized and cured by ultraviolet irradiation, heating, or the like to form a non-fluid layer, and at the same time, also. Any layer may be used as long as it is a layer that has changed to a state in which the orientation form is not changed by an external field or an external force.
  • the optical properties of the cholesteric liquid crystal phase are retained in the layer, and the liquid crystal compound in the layer does not have to exhibit liquid crystal property anymore.
  • the polymerizable liquid crystal compound may have a high molecular weight due to a curing reaction and no longer have liquid crystal properties.
  • the cholesteric liquid crystal phase is known to selectively reflect the circularly polarized light of either the right-handed or left-handed circularly polarized light, and to exhibit the circularly polarized light selective reflection that transmits the circularly polarized light of the other sense. ..
  • a film containing a layer in which a cholesteric liquid crystal phase exhibiting circularly polarized selective reflectivity is fixed many films formed from a composition containing a polymerizable liquid crystal compound have been known conventionally, and the cholesteric liquid crystal layer has been conventionally known. You can refer to the technology.
  • ⁇ P the average refractive index
  • the selective reflection center wavelength can be adjusted by adjusting the n value and / or the P value.
  • the pitch P (one spiral pitch) of the spiral orientation structure is, in other words, the length in the spiral axis direction for one spiral winding, that is, the director (rod-shaped liquid crystal) of the liquid crystal compound constituting the cholesteric liquid crystal phase.
  • the length in the long axis direction is the length in the spiral axis direction that rotates 360 °.
  • the direction of the spiral axis of the normal cholesteric liquid crystal layer coincides with the thickness direction of the cholesteric liquid crystal layer.
  • the selective reflection center wavelength and the full width at half maximum of the cholesteric liquid crystal layer can be obtained as an example as follows.
  • a spectrophotometer manufactured by JASCO Corporation, V-670
  • a decrease peak in transmittance is observed in the selective reflection band.
  • the value of the wavelength on the short wavelength side is ⁇ l (nm)
  • the value of the wavelength on the long wavelength side is ⁇ h (nm)
  • the selective reflection center wavelength ⁇ and the half-value width ⁇ can be expressed by the following equations.
  • the selective reflection center wavelength obtained as described above substantially coincides with the wavelength at the center of gravity of the reflection peak of the circularly polarized reflection spectrum measured from the normal direction of the cholesteric liquid crystal layer.
  • the reflectance on the surface of the first glass 12 can be lowered by using the windshield glass 10 so that the light is obliquely incident on the windshield glass 10.
  • light is obliquely incident on the cholesteric liquid crystal layer constituting the reflective layer 18.
  • light incident at an angle of 45 ° to 70 ° with respect to the normal of the windshield glass 10 in air having a refractive index of 1 causes an angle of about 26 ° to 36 ° on the cholesteric liquid crystal layer having a refractive index of about 1.61.
  • the reflected wavelength shifts to the short wavelength side.
  • the cholesteric liquid crystal layer having the center wavelength of selective reflection in the range of 650 to 780 nm can reflect the projected light in the range of 520 to 695 nm. Since such a wavelength range is a wavelength range with high luminosity factor, the contribution to the brightness of the projected image is high, and as a result, a projected image with high brightness can be realized.
  • the spiral pitch of the cholesteric liquid crystal phase depends on the type of chiral agent used together with the polymerizable liquid crystal compound and the concentration thereof added, a desired pitch can be obtained by adjusting these.
  • a desired pitch can be obtained by adjusting these.
  • the cholesteric liquid crystal layers are arranged in order from the one having the shortest center wavelength of selective reflection when viewed from the visual side, that is, from the inside of the vehicle.
  • each cholesteric liquid crystal layer a cholesteric liquid crystal layer having a spiral sense of either right or left is used.
  • the sense of circularly polarized light reflected by the cholesteric liquid crystal layer matches the sense of spiral.
  • the spiral senses of the cholesteric liquid crystal layers may all be the same or may include different ones. However, it is preferable that the plurality of cholesteric liquid crystal layers all have the same spiral sense, that is, the turning direction of the circularly polarized light that is selectively reflected.
  • the cholesteric liquid crystal layer exhibiting selective reflection in the same or overlapping wavelength regions does not include the cholesteric liquid crystal layer having a different spiral sense. Is preferable. This is to prevent the transmittance in a specific wavelength range from dropping to less than 50%, for example.
  • the ⁇ n can be adjusted by adjusting the type or mixing ratio of the polymerizable liquid crystal compound, or by controlling the temperature at the time of fixing the orientation.
  • a plurality of cholesteric liquid crystal layers having the same pitch P and the same spiral sense may be laminated. By stacking cholesteric liquid crystal layers having the same pitch P and the same spiral sense, it is possible to increase the circular polarization selectivity at a specific wavelength.
  • the reflection layer 18 preferably has a cholesteric liquid crystal layer having a reflection wavelength band in the wavelength range of 540 to 850 nm and a half width of 150 nm or more.
  • the reflective layer 18 becomes a selective reflective layer that selectively reflects light in a wide band.
  • the cholesteric liquid crystal layer separately prepared may be laminated by using an adhesive or the like, or the above-mentioned cholesteric liquid crystal formed by the method described later may be laminated.
  • a liquid crystal composition containing a polymerizable liquid crystal compound or the like may be directly applied to the surface of the layer, and the steps of orientation and fixation may be repeated, but the latter is preferable.
  • the thickness of the cholesteric liquid crystal layer is preferably 0.5 to 10 ⁇ m, more preferably 1.0 to 8.0 ⁇ m, and even more preferably 1.5 to 6.0 ⁇ m.
  • the total thickness of the cholesteric liquid crystal layers is preferably 2.0 to 30 ⁇ m, more preferably 2.5 to 25 ⁇ m, and more preferably 3.0 to 20 ⁇ m. Is even more preferable.
  • the visible light transmittance can be maintained high without reducing the thickness of the cholesteric liquid crystal layer.
  • a material for forming the cholesteric liquid crystal layer and a method for forming the cholesteric liquid crystal layer will be described.
  • the material used for forming the cholesteric liquid crystal layer described above include a liquid crystal composition (coating liquid) containing a polymerizable liquid crystal compound and a chiral agent (optically active compound).
  • a liquid crystal composition that is further mixed with a surfactant, a polymerization initiator, etc. and dissolved in a solvent or the like is applied to a support, an orientation layer, a cholesteric liquid crystal layer as an lower layer, or the like, and after cholesteric orientation aging.
  • the liquid crystal composition can be immobilized by curing to form a cholesteric liquid crystal layer.
  • the polymerizable liquid crystal compound may be a rod-shaped liquid crystal compound or a disk-shaped liquid crystal compound, but is preferably a rod-shaped liquid crystal compound.
  • Examples of the rod-shaped polymerizable liquid crystal compound forming the cholesteric liquid crystal layer include a rod-shaped nematic liquid crystal compound.
  • rod-shaped nematic liquid crystal compounds examples include azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidins, and alkoxy-substituted phenylpyrimidins.
  • Phenyldioxans, trans, and alkenylcyclohexylbenzonitriles are preferably used. Not only low molecular weight liquid crystal compounds but also high molecular weight liquid crystal compounds can be used.
  • the polymerizable liquid crystal compound is obtained by introducing a polymerizable group into the liquid crystal compound.
  • the polymerizable group include an unsaturated polymerizable group, an epoxy group, and an aziridinyl group, and an unsaturated polymerizable group is preferable, and an ethylenically unsaturated polymerizable group is particularly preferable.
  • the polymerizable group can be introduced into the molecule of the liquid crystal compound by various methods.
  • the number of polymerizable groups contained in the polymerizable liquid crystal compound is preferably 1 to 6 in one molecule, and more preferably 1 to 3.
  • Examples of polymerizable liquid crystal compounds include Makromol. Chem. , 190, 2255 (1989), Advanced Materials 5, 107 (1993), US Pat. No.
  • the amount of the polymerizable liquid crystal compound added to the liquid crystal composition is preferably 80 to 99.9% by mass, preferably 85 to 99.5% by mass, based on the solid content mass (mass excluding the solvent) of the liquid crystal composition. % Is more preferable, and 90 to 99% by mass is particularly preferable.
  • the green-blue reflective cholesteric liquid crystal layer 18GB may have a low ⁇ n.
  • the low ⁇ n green-blue reflective cholesteric liquid crystal layer 18GB can be formed by using a low ⁇ n polymerizable liquid crystal compound.
  • the low ⁇ n polymerizable liquid crystal compound will be specifically described.
  • a narrow-band selective reflection layer can be obtained by forming a cholesteric liquid crystal phase using a low ⁇ n polymerizable liquid crystal compound and forming a film in which the cholesteric liquid crystal phase is fixed.
  • the low ⁇ n polymerizable liquid crystal compound include the compounds described in WO2015 / 115390, WO2015 / 147243, WO2016 / 035773, JP-A-2015-163596, and JP-A-2016-53149.
  • the description of WO2016 / 047648 can also be referred to.
  • the liquid crystal compound is also preferably a polymerizable compound represented by the following formula (I) described in WO2016 / 047648.
  • A represents a phenylene group which may have a substituent or a trans-1,4-cyclohexylene group which may have a substituent
  • L is a single bond, -CH 2.
  • the phenylene group in the formula (I) is preferably a 1,4-phenylene group.
  • the substituent when "may have a substituent" for the phenylene group and the trans-1,4-cyclohexylene group is not particularly limited, and is, for example, an alkyl group, a cycloalkyl group, an alkoxy group, or an alkyl ether. Examples thereof include a substituent selected from the group consisting of a group, an amide group, an amino group, a halogen atom, and a group composed of a combination of two or more of the above-mentioned substituents.
  • the phenylene group and the trans-1,4-cyclohexylene group may have 1 to 4 substituents. When having two or more substituents, the two or more substituents may be the same or different from each other.
  • the alkyl group may be either linear or branched.
  • the alkyl group preferably has 1 to 30 carbon atoms, more preferably 1 to 10 carbon atoms, and even more preferably 1 to 6 carbon atoms.
  • Examples of alkyl groups include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, isopentyl group and neopentyl.
  • alkyl group 1,1-dimethylpropyl group, n-hexyl group, isohexyl group, linear or branched heptyl group, octyl group, nonyl group, decyl group, undecyl group, or dodecyl group can be mentioned.
  • the above description regarding the alkyl group is the same for the alkoxy group containing the alkyl group.
  • specific examples of the alkylene group when referred to as an alkylene group include a divalent group obtained by removing one arbitrary hydrogen atom in each of the above-mentioned examples of an alkyl group.
  • the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.
  • the number of carbon atoms of the cycloalkyl group is preferably 3 to 20, more preferably 5 or more, preferably 10 or less, more preferably 8 or less, still more preferably 6 or less.
  • Examples of the cycloalkyl group include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, and a cyclooctyl group.
  • X 3 represents a single bond, -O-, -S-, or -N (Sp 4- Q 4 )-, or a nitrogen atom forming a ring structure with Q 3 and Sp 3. show.
  • Sp 3 and Sp 4 are independently one or more-in a single bond, a linear or branched alkylene group having 1 to 20 carbon atoms, and a linear or branched alkylene group having 1 to 20 carbon atoms.
  • the replacement position is not particularly limited. Of these, a tetrahydrofuranyl group is preferable, and a 2-tetrahydrofuranyl group is particularly preferable.
  • the m-1 Ls may be the same or different from each other.
  • Sp 1 and Sp 2 are independently one or more-in a single bond, a linear or branched alkylene group having 1 to 20 carbon atoms, and a linear or branched alkylene group having 1 to 20 carbon atoms.
  • the linking group selected from the group consisting of substituted groups is shown.
  • Q 1 and Q 2 each independently represent a polymerizable group selected from the group consisting of a hydrogen atom or a group represented by the above formulas Q-1 to Q-5, where Q 1 and Q 2 have . Either one shows a polymerizable group.
  • the polymerizable group an acryloyl group (formula Q-1) or a methacryloyl group (formula Q-2) is preferable.
  • m represents an integer of 3 to 12.
  • m is preferably an integer of 3 to 9, more preferably an integer of 3 to 7, and even more preferably an integer of 3 to 5.
  • the polymerizable compound represented by the formula (I) has at least one phenylene group which may have a substituent as A and a trans-1,4-cyclohexylene group which may have a substituent. It is preferable to include at least one.
  • the polymerizable compound represented by the formula (I) preferably contains 1 to 4 trans-1,4-cyclohexylene groups which may have a substituent as A, and preferably contains 1 to 3 groups. Is more preferable, and it is more preferable to contain 2 or 3 of them.
  • the polymerizable compound represented by the formula (I) preferably contains 1 or more phenylene groups as A, which may have a substituent, and more preferably 1 to 4 groups. It is more preferable to include 3 pieces, and it is particularly preferable to contain 2 or 3 pieces.
  • polymerizable compound represented by the formula (I) in addition to the compounds described in paragraphs 0051 to 0058 of WO2016 / 047648, Japanese Patent Application Laid-Open No. 2013-112631, Japanese Patent Application Laid-Open No. 2010-070543, Examples thereof include the compounds described in Japanese Patent No. 4725516, WO2015 / 115390, WO2015 / 147243, WO2016 / 035873, JP-A-2015-163596, and JP-A-2016-53149.
  • the chiral agent has the function of inducing the helical orientation structure of the cholesteric liquid crystal phase. Since the chiral compound has a different sense of spiral or spiral pitch to be induced depending on the compound, it may be selected according to the purpose.
  • the chiral agent is not particularly limited, and known compounds can be used. Examples of chiral agents include liquid crystal device handbooks (Chapter 3, 4-3, TN, chiral agents for STN, p. 199, Japan Society for the Promotion of Science 142, 1989), Japanese Patent Application Laid-Open No. 2003-287623, Japan. Examples thereof include compounds described in JP-A-2002-302487, JP-A-2002-80478, JP-A-2002-80851, JP-A-2010-181852, and JP-A-2014-034581.
  • the chiral agent generally contains an asymmetric carbon atom, but an axial asymmetric compound or a surface asymmetric compound that does not contain an asymmetric carbon atom can also be used as the chiral agent.
  • axial or asymmetric compounds include binaphthyl, helicene, paracyclophane, and derivatives thereof.
  • the chiral agent may have a polymerizable group. When both the chiral agent and the liquid crystal compound have a polymerizable group, the repeating unit derived from the polymerizable liquid crystal compound and the repeating unit derived from the chiral agent are derived by the polymerization reaction between the polymerizable chiral agent and the polymerizable liquid crystal compound. Polymers with repeating units can be formed.
  • the polymerizable group of the polymerizable chiral agent is preferably a group of the same type as the polymerizable group of the polymerizable liquid crystal compound. Therefore, the polymerizable group of the chiral agent is preferably an unsaturated polymerizable group, an epoxy group or an aziridinyl group, more preferably an unsaturated polymerizable group, and preferably an ethylenically unsaturated polymerizable group. Especially preferable. Moreover, the chiral agent may be a liquid crystal compound.
  • an isosorbide derivative As the chiral agent, an isosorbide derivative, an isomannide derivative, a binaphthyl derivative and the like can be preferably used.
  • As the isosorbide derivative a commercially available product such as LC756 manufactured by BASF may be used.
  • the content of the chiral agent in the liquid crystal composition is preferably 0.01 to 200 mol%, more preferably 1 to 30 mol% of the amount of the polymerizable liquid crystal compound.
  • the content of the chiral agent in the liquid crystal composition is intended to be the concentration (mass%) of the chiral agent with respect to the total solid content in the composition.
  • the liquid crystal composition preferably contains a polymerization initiator.
  • the polymerization initiator used is preferably a photopolymerization initiator capable of initiating the polymerization reaction by irradiation with ultraviolet rays.
  • photopolymerization initiators include ⁇ -carbonyl compounds (described in US Pat. No. 2,376,661 and US Pat. No. 2,376,670), acidoin ethers (described in US Pat. No. 2,448,828), and ⁇ -hydrogens. Substituted aromatic acidoine compounds (described in US Pat. No.
  • acylphosphine oxide compound or an oxime compound is also preferable to use as the polymerization initiator.
  • acylphosphine oxide compound for example, a commercially available IRGACURE810 manufactured by BASF Japan Ltd. (compound name: bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide) can be used.
  • Examples of the oxime compound include IRGACURE OXE01 (manufactured by BASF), IRGACURE OXE02 (manufactured by BASF), TR-PBG-304 (manufactured by Joshu Powerful Electronics New Materials Co., Ltd.), ADEKA ARCULS NCI-831, and ADEKA ARCULS NCI-930.
  • Commercially available products such as (manufactured by ADEKA) and ADEKA Arkuru's NCI-831 (manufactured by ADEKA) can be used. Only one type of polymerization initiator may be used, or two or more types may be used in combination.
  • the content of the photopolymerization initiator in the liquid crystal composition is preferably 0.1 to 20% by mass, more preferably 0.5 to 5% by mass, based on the content of the polymerizable liquid crystal compound.
  • the liquid crystal composition may optionally contain a cross-linking agent in order to improve the film strength and durability after curing.
  • a cross-linking agent one that cures with ultraviolet rays, heat, humidity or the like can be preferably used.
  • the cross-linking agent is not particularly limited and may be appropriately selected depending on the intended purpose.
  • cross-linking agent examples include polyfunctional acrylate compounds such as trimethylolpropane tri (meth) acrylate and pentaerythritol tri (meth) acrylate; epoxy compounds such as glycidyl (meth) acrylate and ethylene glycol diglycidyl ether; 2,2- Aziridine compounds such as bishydroxymethylbutanol-tris [3- (1-aziridinyl) propionate], 4,4-bis (ethyleneiminocarbonylamino) diphenylmethane; isocyanate compounds such as hexamethylenediisocyanate and biuret-type isocyanate; oxazoline group side Polyoxazoline compounds contained in the chain; alkoxysilane compounds such as vinyltrimethoxysilane and N- (2-aminoethyl) 3-aminopropyltrimethoxysilane can be mentioned.
  • polyfunctional acrylate compounds such as trimethylolpropane tri (meth)
  • a known catalyst can be used depending on the reactivity of the cross-linking agent, and the productivity can be improved in addition to the improvement of the film strength and the durability. These may be used alone or in combination of two or more.
  • the content of the cross-linking agent is preferably 3 to 20% by mass, more preferably 5 to 15% by mass. By setting the content of the cross-linking agent to 3% by mass or more, the effect of improving the cross-linking density can be obtained, and by setting the content of the cross-linking agent to 20% by mass or less, the stability of the cholesteric liquid crystal layer is lowered. Can be prevented.
  • "(meth) acrylate” is used in the meaning of "any one or both of acrylate and methacrylate".
  • orientation control agent An orientation control agent may be added to the liquid crystal composition that contributes to the stable or rapid planar orientation of the cholesteric liquid crystal layer.
  • the orientation control agent include the fluorine (meth) acrylate-based polymers described in paragraphs [0018] to [0043] of JP-A-2007-272185, and paragraphs [0031]-[0031] of JP-A-2012-203237. 0034] and the like, and examples thereof include compounds represented by the formulas (I) to (IV) described in JP-A-2013-113913.
  • the orientation control agent one type may be used alone, or two or more types may be used in combination.
  • the amount of the orientation control agent added to the liquid crystal composition is preferably 0.01 to 10% by mass, more preferably 0.01 to 5% by mass, and 0.02 to 1 to the total mass of the polymerizable liquid crystal compound. Mass% is particularly preferred.
  • the liquid crystal composition may contain at least one selected from various additives such as a surfactant for adjusting the surface tension of the coating film and making the thickness uniform, and a polymerizable monomer. .. Further, in the liquid crystal composition, if necessary, a polymerization inhibitor, an antioxidant, an ultraviolet absorber, a light stabilizer, a coloring material, metal oxide fine particles, etc. are added in a range that does not deteriorate the optical performance. Can be added with.
  • the cholesteric liquid crystal layer is a liquid crystal composition obtained by dissolving a polymerizable liquid crystal compound, a chiral agent, a polymerization initiator and a surfactant added as necessary in a solvent, and a transparent base material 26 and a retardation layer, which will be described later.
  • an alignment film, a cholesteric liquid crystal layer prepared earlier, or the like is applied and dried to obtain a coating film, and the coating film is irradiated with active light to polymerize the cholesteric liquid crystal composition to polymerize the cholesteric liquid crystal composition. It is possible to form a cholesteric liquid crystal layer in which regularity is fixed.
  • the laminated film composed of a plurality of cholesteric liquid crystal layers can be formed by repeating the above-mentioned manufacturing process of the cholesteric liquid crystal layer.
  • the solvent used for preparing the liquid crystal composition is not particularly limited and may be appropriately selected depending on the intended purpose, but an organic solvent is preferably used.
  • the organic solvent is not particularly limited and may be appropriately selected depending on the intended purpose.
  • the method for applying the liquid crystal composition to the support, the alignment layer, the cholesteric liquid crystal layer as the lower layer, and the like is not particularly limited and may be appropriately selected depending on the intended purpose.
  • the coating method include wire bar coating method, curtain coating method, extrusion coating method, direct gravure coating method, reverse gravure coating method, die coating method, spin coating method, dip coating method, spray coating method, and slide coating. Law etc. can be mentioned. It can also be carried out by transferring the liquid crystal composition separately coated on the support.
  • the liquid crystal molecules are oriented by heating the applied liquid crystal composition.
  • the heating temperature is preferably 200 ° C. or lower, more preferably 130 ° C. or lower.
  • the liquid crystal composition can be cured by further polymerizing the oriented liquid crystal compound.
  • the polymerization may be either thermal polymerization or photopolymerization using light irradiation, but photopolymerization is preferable. It is preferable to use ultraviolet rays for light irradiation.
  • the irradiation energy is preferably 20mJ / cm 2 ⁇ 50J / cm 2, more preferably 100 ⁇ 1,500mJ / cm 2.
  • light irradiation may be carried out under heating conditions or a nitrogen atmosphere.
  • the irradiation ultraviolet wavelength is preferably 350 to 430 nm.
  • the polymerization reaction rate is preferably high, preferably 70% or more, and more preferably 80% or more.
  • the polymerization reaction rate can be determined by measuring the consumption ratio of the polymerizable functional group by measuring the infrared absorption spectrum.
  • the polarization conversion layer 24, the reflective layer 18 having the cholesteric liquid crystal layer described above, and the second glass 14 are arranged in this order on the convex side of the first glass 12 which is a curved glass.
  • the projector irradiates the projected light of p-polarized light and incidents on the windshield glass 10.
  • the windshield glass 10 of the present invention reflects the projected light by the reflective layer 18 having the cholesteric liquid crystal layer in which the cholesteric liquid crystal phase is fixed.
  • the cholesteric liquid crystal layer basically selectively reflects right-handed or left-handed circularly polarized light.
  • the polarization conversion layer 24 converts the p-polarized light (linearly polarized light) irradiated from the projector into right-handed circularly polarized light or left-handed circularly polarized light that is selectively reflected by the cholesteric liquid crystal layer.
  • the polarization conversion layer 24 is a layer in which the spiral orientation structure of the liquid crystal compound is fixed, and the pitch number x and the film thickness y [ ⁇ m] of the spiral orientation structure are the following relational expressions (a) to (c). It satisfies all of. (A) 0.1 ⁇ x ⁇ 1.0 (B) 0.5 ⁇ y ⁇ 3.0 (C) 3000 ⁇ (1560 * y) / x ⁇ 50000 Similar to the cholesteric liquid crystal layer described above, in the spiral alignment structure of the liquid crystal compound constituting the polarization conversion layer 24, the pitch of the spiral alignment structure (one spiral pitch) is the length in the spiral axis direction for one spiral winding.
  • the pitch number 1 of the spiral orientation structure of the liquid crystal compound is one spiral winding number.
  • the state in which the director of the liquid crystal compound constituting the polarization conversion layer 24 is rotated by 360 ° is defined as the pitch number 1.
  • Such a polarization conversion layer 24 has a thickness of 0.5 to 3 ⁇ m, and has a spiral orientation structure in which the number of pitches is 0.1 to 1 pitch. That is, the polarization conversion layer 24 has a length in which the pitch of the spirally oriented structure corresponds to the pitch P of the cholesteric liquid crystal layer in which the selective reflection center wavelength is in the long wavelength infrared region.
  • Such a polarization conversion layer 24 exhibits high optical rotation and birefringence with respect to visible light having a short wavelength with respect to the infrared region.
  • the polarization conversion layer 24 can convert p-polarized light (linearly polarized light) incident from the first glass 12 side into right-handed circularly polarized light or left-handed circularly polarized light that is selectively reflected by the reflective layer 18. Further, the polarization conversion layer 24 can return the circularly polarized light reflected by the reflection layer 18 to p-polarized light and irradiate the projected light at the observation position of the driver.
  • polarized sunglasses are designed to block s-polarized light. Therefore, in the conventional HUD that projects s-polarized light, when the driver wears polarized sunglasses, the projected light of the HUD cannot be observed.
  • the observation position of the projected image by the driver can be irradiated with the projected light of p-polarized light. Therefore, according to the windshield glass 10 of the present invention, the projected image of p-polarized light can be projected, so that the projected image of the HUD can be suitably observed even when the driver wears polarized sunglasses.
  • the windshield glass 10 of the present invention not only enables the observation of the projected image by the HUD while wearing the polarized sunglasses, but also has good suitability for the polarized sunglasses against the glaring external light incident from the outside of the vehicle. ..
  • a window using a half mirror film in which a cholesteric liquid crystal layer and a retardation layer such as a ⁇ / 2 plate are combined is used.
  • a configuration using shielded glass is known.
  • this windshield glass converts the incident p-polarized light into circularly polarized light in the retardation layer, reflects this circularly polarized light in the cholesteric liquid crystal layer, and returns the reflected light to p-polarized light in the retardation layer. And irradiate as projected light. This makes it possible to observe the projected image of the HUD even when the driver is wearing polarized sunglasses.
  • the polarized state changes.
  • the glare component that penetrates from the outside of the windshield glass is s-polarized light. Therefore, the s-polarized light transmitted through the cholesteric liquid crystal layer that selectively reflects the circularly polarized light corresponding to the p-polarized light is ideally the circularly polarized light in the turning direction corresponding to the s-polarized light. This circularly polarized light is then converted into s-polarized light again by the retardation layer. Therefore, s-polarized light, which is a glare component that penetrates from the outside of the windshield glass, can be shielded from light by using polarized sunglasses.
  • the s-polarized light incident on the windshield glass from the outside is incident on the windshield glass at various angles as well as the component incident on the cholesteric liquid crystal layer of the windshield glass from the normal direction. Therefore, in the HUD in which p-polarized light is projected by the conventional retardation layer and cholesteric liquid crystal layer as shown in Patent Document 1, the s-polarized light that has penetrated from the outside and transmitted through the cholesteric liquid crystal layer is not circularly polarized light. It becomes elliptically polarized light. When such elliptically polarized light passes through the retardation layer, not only s-polarized light but also p-polarized light components are mixed in the transmitted light.
  • polarized sunglasses Since p-polarized light cannot be shielded by polarized sunglasses, it passes through polarized sunglasses. Therefore, in the conventional HUD that projects p-polarized light, the function of polarized sunglasses that shields reflected light that becomes glaring, which is mainly composed of s-polarized light, is impaired, which hinders driving. That is, a windshield glass using a half mirror film using a retardation layer and a circularly polarized light reflecting layer that projects conventional p-polarized light as shown in Patent Document 1 has low suitability for polarized sunglasses against external light.
  • the windshield glass of the present invention is not a retardation layer generally used as an element for converting p-polarized light (linearly polarized light) into circularly polarized light, but has a spiral orientation structure of a liquid crystal compound as described above.
  • the polarization conversion layer 24 is used.
  • the windshield glass of the present invention has such a polarization conversion layer 24 inside the vehicle from the reflection layer 18, that is, the cholesteric liquid crystal layer.
  • the p-polarized light component can be returned to s-polarized light again. That is, according to the windshield glass 10 of the present invention, the glaring s-polarized light that invades from the outside of the vehicle can be passed while maintaining the s-polarized state.
  • the windshield glass 10 of the present invention s-polarized light incident from the outside of the vehicle, which becomes glaring, can be shielded by polarized sunglasses, and excellent suitability for polarized sunglasses against external light is exhibited. ..
  • the swirling direction (spiral sense) of the spirally oriented structure in the polarization conversion layer 24 may be set according to the swirling direction of circularly polarized light selectively reflected by the cholesteric liquid crystal layer constituting the reflective layer 18. For example, when the cholesteric liquid crystal layer selectively reflects right-handed circularly polarized light, the spiral turning direction of the polarization conversion layer 24 is clockwise toward the reflective layer 18. On the contrary, when the cholesteric liquid crystal layer selectively reflects the left-handed circularly polarized light, the spiral turning direction of the polarization conversion layer 24 is counterclockwise toward the reflective layer 18.
  • the polarization conversion layer 24 satisfies all the relational expressions (a) to (c) in the pitch number x and the film thickness y of the spiral orientation structure.
  • the relational expression (a) is “0.1 ⁇ x ⁇ 1.0”. If the number of pitches x of the spirally oriented structure is less than 0.1, inconveniences such as insufficient optical rotation and birefringence occur. On the other hand, if the number of pitches x of the spirally oriented structure exceeds 1.0, the optical rotation and birefringence are excessive, which causes inconveniences such as not being able to obtain desired circularly polarized light.
  • the relational expression (b) is “0.5 ⁇ y ⁇ 3.0”. If the thickness y of the polarization conversion layer 24 is less than 0.5 ⁇ m, the film thickness is too thin, causing inconveniences such as insufficient optical rotation and birefringence. If the thickness y of the polarization conversion layer 24 exceeds 3.0 ⁇ m, the optical rotation and birefringence are excessive, causing inconveniences such as not being able to obtain desired elliptically polarized light.
  • the relational expression (c) is “3000 ⁇ (1560 * y) / x ⁇ 50000”. If “(1560 * y) / x" with the pitch number x and the thickness y [ ⁇ m] of the spirally oriented structure of the polarization conversion layer 24 as parameters is less than 3000, the optical rotation is excessive and the desired polarized light cannot be obtained. And other inconveniences occur. If “(1560 * y) / x" exceeds 50,000, the optical rotation is insufficient and desired polarization cannot be obtained.
  • the polarization conversion layer 24 preferably satisfies all of the following relational expressions (d) to (f). (D) 0.2 ⁇ x ⁇ 0.8 (E) 0.6 ⁇ y ⁇ 2.0 (F) 6000 ⁇ (1560 * y) / x ⁇ 10000
  • the polarization conversion layer 24 has a longer pitch P of a spirally oriented structure and a smaller number of pitches x.
  • the spiral pitch P is equal to the pitch P of the cholesteric liquid crystal layer in which the selective reflection center wavelength is in the long wavelength infrared region, and the pitch number x is small.
  • the polarization conversion layer 24 has a spiral pitch P equivalent to the pitch P of the cholesteric liquid crystal layer having a selective reflection center wavelength of 3000 to 8000 nm and a small pitch number x. Since the selective reflection center wavelength corresponding to the pitch P of such a polarization conversion layer 24 is much longer than that of visible light, the above-mentioned optical rotation and birefringence with respect to visible light are more preferably exhibited. ..
  • Such a polarization conversion layer 24 can be basically formed in the same manner as the cholesteric liquid crystal layer described above. However, when forming the polarization conversion layer 24, it is preferable that the pitch number x and the film thickness y [ ⁇ m] of the spiral orientation structure in the polarization conversion layer 24 satisfy all the relational expressions (a) to (c). It is necessary to adjust the liquid crystal compound to be used, the chiral agent to be used, the amount of the chiral agent added, the film thickness, and the like so as to satisfy all the relational expressions (d) to (f).
  • the retardation layer 28 is provided on the reflective layer 18. As described above, the retardation layer 28 is provided as a preferred embodiment, and is provided between the reflection layer 18 (cholesteric liquid crystal layer) and the second glass 14. When the windshield glass has the transparent base material 26 and the heat seal layer 20, the retardation layer 28 is preferably provided on the reflective layer 18 rather than both, as shown in the illustrated example. In the present invention, the retardation layer 28 has a front retardation of 50 to 170 nm at a wavelength of 550 nm, preferably 50 to 140 nm.
  • the retardation layer 28 has a slow phase axis of ⁇ when the direction corresponding to the upper side of the vertical direction on the surface of the first glass 12 is 0 ° (reference) when the windshield glass is mounted on the vehicle.
  • the angle is 10 to 50 °.
  • the retardation layer 28 is the slow axis.
  • the angle ⁇ should be ⁇ 10 to 50 °.
  • the windshield glass 10 of the present invention has the polarization conversion layer 24 inside the vehicle from the reflective layer 18 (cholesteric liquid crystal layer), so that the s-polarized light that becomes glare incident from the outside of the vehicle can be s-polarized. It has good polarized sunglasses suitability for external light that can be retained and transmitted. As a preferred embodiment, the windshield glass 10 of the present invention has the retardation layer 28, so that the s-polarized light that becomes glaring incident from the outside of the vehicle can be more preferably transmitted while maintaining the s-polarized light, and the outside light can be transmitted. The suitability for polarized sunglasses can be further improved.
  • polarized sunglasses are designed to block s-polarized light.
  • the s-polarized light that has entered from the outside of the vehicle passes through the cholesteric liquid crystal layer constituting the reflective layer 18, the polarized light changes and the p-polarized light component is mixed. Since polarized sunglasses block s-polarized light, this p-polarized component passes through the polarized sunglasses. Therefore, in the conventional HUD that displays the projected image with p-polarized light, there is a problem that the function of the polarized sunglasses that blocks the glare of the reflected light incident from the outside of the vehicle is impaired, which hinders driving.
  • the windshield glass 10 of the present invention preferably has a retardation layer 28 between the reflective layer 18, that is, the cholesteric liquid crystal layer and the second glass 14.
  • the glaring s-polarized light incident from the outside of the vehicle is incident on the retardation layer 28 before being incident on the cholesteric liquid crystal layer.
  • the glaring s-polarized light incident on the retardation layer 28 is converted into elliptically polarized light in the swirling direction according to the s-polarized light due to the phase difference of the retardation layer 28.
  • the elliptically polarized light transmitted through the retardation layer 28 is then incident on the reflection layer 18, that is, the cholesteric liquid crystal layer.
  • the swirling direction of the elliptically polarized light converted from the s-polarized light is not a reflection component by the cholesteric liquid crystal layer, it is transmitted through the cholesteric liquid crystal layer and converted into circularly polarized light in the swirling direction corresponding to the s-polarized light.
  • This circularly polarized light is then converted into s-polarized light by passing through the polarization conversion layer 24 and passes through the windshield glass 10. That is, since the windshield glass 10 of the present invention has the retardation layer 28, the glaring s-polarized light that has entered from the outside of the windshield glass is more preferably transmitted as the s-polarized light, so that it is shielded by polarized sunglasses. can. Therefore, since the windshield glass 10 of the present invention has the retardation layer 28, it is possible to more preferably improve the suitability of polarized sunglasses for external light in the HUD on which p-polarized light is projected.
  • the retardation layer 28 used in the windshield glass 10 of the present invention has a front retardation of 50 to 170 nm at a wavelength of 550 nm, preferably 50 to 140 nm.
  • the front retardation is 50 to 170 nm, preferably 50 to 140 nm, birefringence is appropriate and s-polarized light of external light can be converted into appropriate elliptically polarized light, which is preferable.
  • the front retardation of the retardation layer 28 is more preferably 70 to 130 nm, further preferably 90 to 130 nm, and particularly preferably 90 to 120 nm.
  • the retardation layer 28 used in the windshield glass 10 of the present invention has a slow axis angle of ⁇ 10 to ⁇ 10 when the direction corresponding to the upper side of the vertical direction on the surface of the first glass 12 is 0 °. It is 50 °.
  • the angle of the slow axis is ⁇ 10 to 50 °, the s-polarized light of the external light can be converted into an appropriate elliptically polarized light, which is preferable.
  • the angle of the slow axis is preferably ⁇ 15 to 48 °, more preferably ⁇ 30 to 45 °.
  • the “+” / “ ⁇ ” angle of the slow axis of the retardation layer 28 is determined by the twisting direction (sense) of the spiral of the cholesteric liquid crystal layer, that is, the turning direction of the circularly polarized light that is selectively reflected. Specifically, when the cholesteric liquid crystal layer selectively reflects right circularly polarized light, the angle of the slow axis is "+", and when it selectively reflects left circularly polarized light, it is "-”. The angle of the slow axis of the retardation layer 28 is “+” in the clockwise direction and “ ⁇ ” plus in the counterclockwise direction with respect to 0 °.
  • the retardation layer 28 is not limited and can be appropriately selected depending on the intended purpose.
  • the retardation layer 28 include a stretched polycarbonate film, a stretched norbornene-based polymer film, a transparent film oriented containing inorganic particles having birefringence such as strontium carbonate, and an inorganic dielectric on a support.
  • examples thereof include a thin film obtained by obliquely depositing a body, a film in which a polymerizable liquid crystal compound is uniaxially oriented and fixed, and a film in which a liquid crystal compound is uniaxially oriented and fixed in orientation.
  • a film in which a polymerizable liquid crystal compound is uniaxially oriented and oriented and fixed is preferably exemplified as a retardation layer 28.
  • a liquid crystal composition containing a polymerizable liquid crystal compound is applied to the surface of a temporary support or an alignment layer, and the polymerizable liquid crystal compound in the liquid crystal composition is nematically applied in a liquid crystal state. After forming in an orientation, it can be fixed by curing to form.
  • the retardation layer 28 can be formed in the same manner as the cholesteric liquid crystal layer described above, except that a chiral agent is not added to the liquid crystal composition.
  • the heating temperature is preferably 50 to 120 ° C, more preferably 60 to 100 ° C.
  • the retardation layer 28 is obtained by applying a composition containing a polymer liquid crystal compound to the surface of a temporary support, an orientation layer, or the like to form a nematic orientation in a liquid crystal state, and then cooling to fix the orientation. It may be a layer to be used.
  • the thickness of the retardation layer 28 is not limited, but is preferably 0.2 to 300 ⁇ m, more preferably 0.5 to 150 ⁇ m, and even more preferably 1.0 to 80 ⁇ m.
  • the thickness of the retardation layer 28 formed from the liquid crystal composition is not particularly limited, but is preferably 0.2 to 10 ⁇ m, more preferably 0.5 to 5.0 ⁇ m, and further preferably 0.7 to 2.0 ⁇ m. preferable.
  • a layer having a fixed spiral orientation structure of a liquid crystal compound similar to the above-mentioned polarization conversion layer 24 may be provided.
  • the suitability of polarized sunglasses for external light can be further improved.
  • the transparent base material 26 is provided on the retardation layer 28.
  • the transparent base material 26 is provided as a preferred embodiment, and is provided between the reflective layer 18 (cholesteric liquid crystal layer) and the second glass 14.
  • the transparent base material 26 is preferably provided between the retardation layer 28 and the second glass 14.
  • the reflective layer 18 (cholesteric liquid crystal layer) is formed using the transparent base material 26 as a base material, and the polarization conversion layer 24 is placed on the reflective layer 18. Can be formed.
  • the retardation layer 28 is formed on the transparent base material 26
  • the reflection layer 18 is formed on the transparent base material 26
  • the polarization conversion layer 24 is formed on the reflection layer 18.
  • the reflective layer 18 and the retardation layer 28 may be formed after the transparent base material 26 is subjected to an orientation treatment.
  • the heat seal layer 20 described later is provided on the surface of the transparent base material 26 opposite to the reflective layer 18, and the heat seal layer 20 makes the reflective layer 18 and the like a second glass 14. It becomes possible to attach to.
  • the material for forming the transparent base material 26 is not limited, and various materials can be used as long as sufficient transparency can be ensured.
  • resin materials such as triacetyl cellulose (TAC) and copolyester (coPEN) of naphthalate 70 / terephthalate 30 (mol%) are exemplified.
  • the thickness of the transparent base material 26 is not limited, and a thickness that can secure sufficient strength as a base material may be appropriately set according to the material for forming the transparent base material 26.
  • the thickness of the transparent base material 26 is preferably 10 to 250 ⁇ m, more preferably 15 to 90 ⁇ m.
  • the transparent base material 26 may be oriented.
  • the alignment treatment also includes the formation of an alignment film.
  • the method of orientation treatment is not limited, and various known methods can be used. As an example, rubbing treatment, oblique deposition of inorganic compounds, formation of layers with microgrooves, and organic compounds using the Langmuir-Blojet method (LB film) (eg, ⁇ -tricosanoic acid, dioctadecylmethylammonium chloride). And methods such as accumulation of methyl stearylate, etc.) are available.
  • LB film Langmuir-Blojet method
  • the transparent base material 26 may contain an ultraviolet absorber, if necessary.
  • the external light incident on the windshield glass 10 includes ultraviolet rays. This ultraviolet ray deteriorates the reflective layer 18 (cholesteric liquid crystal layer), and as a result, the reflectance of the projected light is lowered and the color of the reflected light is changed.
  • the transparent base material 26 contains an ultraviolet absorber, deterioration of the reflective layer 18 due to ultraviolet rays can be prevented, and the light resistance of the windshield glass 10 can be improved.
  • the interlayer film 16 may have an ultraviolet absorber, if necessary.
  • the ultraviolet absorber used in the present invention is not limited, and various known ultraviolet absorbers can be used.
  • the ultraviolet absorber for example, the ultraviolet absorbers described in JP-A-2012-056995, JP-A-2006-328277, JP-A-2012-31313, and the like can be preferably used.
  • the wavelength range of the ultraviolet rays absorbed by the ultraviolet absorber is not limited, and the ultraviolet rays in the wavelength range in which the deterioration progresses may be absorbed depending on the material for forming the reflective layer 18 and the like.
  • the ultraviolet absorber an ultraviolet absorber having a maximum absorption wavelength in the wavelength range of 300 to 380 nm is preferably used. More preferably, an ultraviolet absorber having a maximum absorption wavelength in the wavelength range of 300 to 360 nm is used.
  • the amount of the ultraviolet absorber added to the reflective layer 18 and the heat seal layer 20 is not limited.
  • the amount capable of obtaining the target ultraviolet absorption rate may be appropriately set according to the ultraviolet absorber used.
  • the method for forming the transparent base material 26 containing the ultraviolet absorber is not limited, and various known methods can be used.
  • an ultraviolet absorber may be added to the molten resin material before the transparent base material 26 is molded into a sheet and mixed. If necessary, such an ultraviolet absorber may be added to the retardation layer 28 and / or the heat seal layer 20 described later.
  • the heat seal layer 20 is provided on the transparent base material 26.
  • the heat seal layer 20 is provided as a preferred embodiment, and is provided between the reflective layer 18 (cholesteric liquid crystal layer) and the second glass 14. More specifically, the heat seal layer 20 is provided in contact with the vehicle inner surface of the second glass 14, and is provided with the second glass 14 and the transparent base material 26 or the retardation layer 28 or the reflective layer 18 (cholesteric liquid crystal layer). ) And are attached.
  • thermoplastic resin As the heat seal layer 20, various layers containing a known thermoplastic resin as a main component can be used.
  • the heat seal layer 20 is preferably transparent.
  • the thermoplastic resin is preferably an amorphous resin.
  • a resin selected from the group consisting of a polyvinyl acetal resin typified by a polyvinyl butyral (PVB) resin, an ethylene-vinyl acetate copolymer, and a chlorine-containing resin can be used.
  • polyvinyl acetal resin typified by polyvinyl butyral resin and ethylene-vinyl acetate copolymer are preferably exemplified, and polyvinyl acetal resin typified by polyvinyl butyral resin (also referred to as alkyl acetalized polyvinyl alcohol) is more preferable.
  • the resin is preferably a synthetic resin.
  • Polyvinyl butyral can be obtained by acetalizing polyvinyl alcohol with butyraldehyde.
  • the preferable lower limit of the acetalization degree of the polyvinyl acetal resin represented by the above-mentioned polyvinyl butyral resin is 40%, the preferable upper limit is 85%, the more preferable lower limit is 60%, and the more preferable upper limit is 80%.
  • the polyvinyl alcohol used as a raw material for these resins is usually obtained by saponifying polyvinyl acetate, and polyvinyl alcohol having a saponification degree of 80 to 99.8 mol% is generally used.
  • the preferable lower limit of the degree of polymerization of polyvinyl alcohol is 200, and the preferable upper limit is 10000.
  • a more preferable lower limit is 500, and a more preferable upper limit is 5000.
  • the degree of polymerization referred to here represents the average degree of polymerization.
  • the polyvinyl acetal resin preferably used for the heat seal layer 20 examples include KS-10, KS-1, KS-3, KS-5, and BL-5 manufactured by Sekisui Chemical Co., Ltd. These polyvinyl acetal resins tend to form a mixed layer with the transparent support when applied to the transparent support. Further, in order to apply a thin layer of the heat seal layer 20, it is important that the coating liquid has a low viscosity. From this point of view, the calculated molecular weight is preferably 10,000 or more and 50,000 or less, and KS-10 and KS-1 are preferable. In the present invention, the calculated molecular weight is defined as a value obtained by multiplying the average degree of polymerization of polyvinyl alcohol as a raw material by the molecular weight of the acetalized unit.
  • the heat seal layer 20 contains a cross-linking agent for cross-linking the polyvinyl alcohol unit in the polyvinyl acetal resin structure in addition to the polyvinyl acetal resin.
  • the cross-linking agent include epoxy-based additives, and a compound having two or more epoxy groups in one molecule is particularly preferable, and a compound represented by the following general formula (EP1) is particularly preferable.
  • Ep-CH 2 -O- (R- O) n -CH 2 -Ep (EP1) Ep is an epoxy group, R is an alkylene group having 2 to 4 carbon atoms, and n is 1 to 30.
  • the plurality of Rs may be the same or different.
  • Specific examples of the compound represented by the above general formula (EP1) include Denacol EX-810, 811, 821, 830, 832, 841, 850, 851, 861, 911, 920, 931 and , 941 and the like.
  • a cationic polymerization initiator which is an onium salt composed of a light-absorbing cation portion and an anion portion which is an acid generation source
  • a sulfonium salt-based or iodonium salt-based cationic polymerization initiator can be used.
  • an iodonium-based cationic polymerization initiator is preferable.
  • the heat seal layer 20 is preferably prepared using the coating composition.
  • the coating composition forming the heat seal layer 20 preferably contains at least one solvent.
  • a solvent that dissolves the thermoplastic resin contained in the heat seal layer 20 is preferable.
  • thermoplastic resin contained in the heat seal layer 20 is polyvinyl butyral, alcohols; methanol, ethanol, isopropyl alcohol, butanol, isobutyl alcohol, diacetone alcohol, and other aromatic hydrocarbons; toluene, and Glycol ethers such as xylene; methyl cellosolve, ethyl cellosolve, butyl cellosolve, and ketones such as cellosolve acetate; ketones; acetone, methyl ethyl ketone, cyclohexanone, methyl isobutyl ketone, diisobutyl ketone, and isophorone, amides; N, N-dimethyl Esters such as acetoamide, N, N-dimethylformamide, and N-methyl-2-pyrrolidone; ethers such as methyl formate, methyl acetate, ethyl acetate, butyl acetate, and ethy
  • the thickness of the heat seal layer 20 is not limited, and the required adhesive force can be obtained and sufficient transparency can be obtained depending on the material for forming the heat seal layer 20.
  • the thickness may be set as appropriate.
  • the thickness of the heat seal layer 20 is preferably 0.2 to 45 ⁇ m. It is preferable that the thickness of the heat seal layer 20 is 0.2 ⁇ m or more in that sufficient adhesive force can be obtained.
  • the thickness of the heat seal layer 20 is more preferably 0.5 to 40 ⁇ m, further preferably 1 to 20 ⁇ m.
  • the windshield glass 10 of the present invention can be basically manufactured according to a known windshield glass (laminated glass) having an interlayer film and a half mirror film.
  • the retardation layer 28 is formed on one surface of the transparent base material 26.
  • the formation surface of the retardation layer 28 of the transparent base material 26 may be subjected to an orientation treatment such as a rubbing treatment.
  • the cholesteric liquid crystal layer is formed on the surface of the retardation layer 28 as described above to form the reflection layer 18, and the polarization conversion layer 24 is further formed on the surface of the reflection layer 18 as described above.
  • a half mirror film having a transparent base material 26 is produced.
  • a heat seal layer 20 is formed on the surface of the transparent base material 26 opposite to the surface on which the reflective layer 18 and the like are formed, for example, by using a coating composition to form a half mirror film structure.
  • An interlayer film 16 is provided on the convex surface side of the first glass 12, and a structure is laminated on the surface of the interlayer film 16 with the polarization conversion layer 24 facing the intermediate film 16 and further, a concave surface side on the heat seal layer 20 of the structure.
  • the second glass 14 is laminated by contacting the two.
  • the interlayer film 16, the polarization conversion layer 24, the reflective layer 18, the retardation layer 28, the transparent base material 26, the heat seal layer 20, and the second glass 14 are placed on the convex surface of the first glass 12 in this order.
  • a laminated body is formed. Next, this laminate is heated at about 90 ° C. under vacuum and temporarily crimped, and then heat-bonded at 110 ° C.
  • the processing conditions of the heat-bonding treatment are not limited, and may be appropriately set according to the forming material and configuration of the interlayer film 16, the reflective layer 18, the heat-sealing layer 20, and the like.
  • Windshield glass without at least one of the interlayer film 16, the transparent base material 26, the retardation layer 28, and the heat seal layer 20 can be manufactured in the same manner.
  • a transparent base material 26, and a retardation layer 28 one surface of a peelable temporary support is subjected to an orientation treatment such as a rubbing treatment as necessary, and then a cholesteric liquid crystal display is used.
  • a layer is formed to form a reflective layer 18, and a polarization conversion layer 24 is further formed on the surface of the reflective layer 18 to produce a half mirror film with a temporary support.
  • An intermediate film 16 is provided on the convex side of the first glass 12, and a half mirror film with a temporary support is laminated on the surface of the intermediate film 16 with the polarization conversion layer 24 facing the intermediate film 16. Then, the peelable temporary support is peeled off. Further, the second glass 14 is laminated with the concave surface side facing the reflective layer. As a result, a laminated body in which the first glass 12, the interlayer film 16, the polarization conversion layer 24, the reflection layer 18, and the second glass 14 are laminated in this order is formed. Next, the windshield glass of the present invention is produced by heat-pressing the laminated body using an autoclave or the like.
  • FIG. 2 conceptually shows an example of the HUD of the present invention.
  • the HUD 30 shown in FIG. 2 has the windshield glass 10 of the present invention described above and the projector 32.
  • the projector 32 shown in FIG. 2 includes an image forming unit 34, an intermediate image screen 36, a mirror 38, and a concave mirror 40.
  • the projected light projected by the projector 32 passes through the transmission window 46 provided on the dashboard 42 of the vehicle equipped with the HUD 30 and is incident on the windshield glass 10 as shown by the alternate long and short dash line. Then, it is reflected by the reflective layer 18 and observed by the driver D. Similar to the known HUD, in the HUD of the illustrated example, the driver D observes a virtual image of the image projected on the windshield glass 10.
  • the image forming unit 34 has an LCD 50 (Liquid Crystal Display) and a projection lens 52. Both the LCD 50 and the projection lens 52 are known ones used in projectors for HUDs.
  • the image forming unit 34 projects the image displayed by the LCD 50 onto the intermediate image screen 36 by the projection lens 52.
  • an intermediate image screen 36 creates a real image, and the real image is reflected by a mirror 38 and a concave mirror 40 in a predetermined optical path. As described above, this reflected light passes through the transmission window 46 provided on the dashboard 42, enters the windshield glass 10, is reflected, and the projected image is observed by the driver D (dashed line). reference).
  • the LCD 50 displays a p-polarized image (projected image) as a preferred embodiment. That is, in the HUD 30 of the present invention, as a preferred embodiment, the projector 32 irradiates the projected light of p-polarized light. Therefore, when the LCD 50 does not display the projected light of p-polarized light, for example, a polarizing plate that converts the projected light from the LCD 50 into p-polarized light is provided in the middle of the optical path of the projected light from the LCD 50 to the concave mirror 40. It is preferable to provide it.
  • a polarizing plate that converts the projected light from the LCD 50 into p-polarized light may be provided outside the projector 32, that is, in the middle of the optical path of the projected light from the concave mirror 40 to the windshield glass 10.
  • the windshield glass 10 converts p-polarized light into circularly polarized light by the polarization conversion layer 24, reflects this circularly polarized light by the reflective layer 18, and returns the circularly polarized light to p-polarized light by the polarization conversion layer 24. .. Thereby, the windshield glass 10 selectively reflects p-polarized light as a preferred embodiment. Therefore, when the projector 32p emits polarized projected light, the p-polarized projected image can be projected, and even when the driver D wears polarized sunglasses, the image projected by the HUD 30 is observed. Will be possible.
  • a polarizing plate in which thin films having different refractive index anisotropy are laminated can be mentioned.
  • the polarizing plate in which thin films having different refractive index anisotropy are laminated for example, those described in Japanese Patent Publication No. 9-506837 can be used.
  • a polarizing plate when processed under the conditions selected to obtain the refractive index relationship, a polarizing plate can be formed using a wide variety of materials. In general, one of the first materials needs to have a different refractive index than the second material in the chosen direction. This difference in refractive index can be achieved by a variety of methods, including stretching, extrusion, or coating during or after film formation.
  • a commercially available product may be used as the polarizing plate in which thin films having different refractive index anisotropy are laminated.
  • a product in which a reflective polarizing plate and a temporary support are laminated may be used. Examples of commercially available products include DBEF (manufactured by 3M) and APF (Advanced Polarizing Film (manufactured by 3M)).
  • DBEF manufactured by 3M
  • APF Advanced Polarizing Film
  • the polarizing plate an absorption type polarizing plate containing an iodine compound and a general linearly polarized light reflecting plate such as a reflective polarizing plate such as a wire grid can also be used.
  • the image forming unit 34 is not limited to the one using the LCD 50, and various known image forming means used in the HUD projector can be used.
  • a HUD projector such as a fluorescent display tube, an LCOS (Liquid Crystal on Silicon) using a liquid crystal display, an organic electroluminescence (organic EL) display, and a DLP (Digital Light Processing) using a DMD (Digital Micromirror Device).
  • Various known image forming means used in the imager can be used. In these image forming means, the projected image is projected on the intermediate image screen 36 by the projection lens as in the LCD 50.
  • an image forming means of the image forming unit 34 a light beam modulated according to the formed image is irradiated from a light source, R light, G light and B light are combined as necessary, and then the light beam is used.
  • An image forming means by optical beam scanning optical beam scanning is also available, which forms a projected image by converting the light into p-polarized light and scanning it two-dimensionally with an optical deflector.
  • the light beam may be modulated according to the projected image by directly modulating the light source or by using an external light modulator.
  • Examples of the light source include an LED (Light Emitting Diode, a light emitting diode, an organic light emitting diode (including an OLED (Organic Light Emitting Diode)), a discharge tube, and a laser light source.
  • Examples of the two-dimensional optical deflector include a galvanometer mirror (galvanometer mirror), a combination of a galvanometer mirror and a polygon mirror, and a MEMS (Micro Electro Mechanical Systems). Among them, MEMS is preferably used.
  • the scanning method is not limited, and known light beam scanning methods such as random scan and raster scan can be used. Among them, raster scan is preferably exemplified.
  • the projected light emitted from the image forming unit 34 is then made into a real image (visible image) by the intermediate image screen 36.
  • the intermediate image screen 36 is not limited, and various known intermediate image screens that realize a projected image in a HUD projector can be used.
  • Examples of the intermediate image screen 36 include a scattering film, a microlens array, and a screen for rear projection.
  • a plastic material is used as the intermediate image screen 36, if the intermediate image screen 36 has birefringence, the polarizing plane and the light intensity of the polarized light incident on the intermediate image screen 36 are disturbed, and as a result, the projected image is colored. Although unevenness and the like are likely to occur, the problem of color unevenness can be reduced by using a retardation layer having a predetermined retardation.
  • the intermediate image screen 36 also has a function of spreading and transmitting the incident projected light. This is because the projected image can be enlarged and displayed.
  • an intermediate image screen composed of a microlens array is exemplified.
  • the microlens array used in the HUD is described in, for example, Japanese Patent Application Laid-Open No. 2012-226303, Japanese Patent Application Laid-Open No. 2010-145745, and Japanese Patent Application Laid-Open No. 2007-523369.
  • the projected light realized by the intermediate image screen 36 is reflected by the mirror 38 and the concave mirror 40 in a predetermined optical path, passes through the transmission window 46 provided in the dashboard 42, and is transmitted through the windshield. It is projected on the glass 10 and observed by the driver D (see the alternate long and short dash line).
  • the mirror 38 is a known mirror used for adjusting the optical path of projected light in a projector. Further, the mirror 38 may be a so-called cold mirror that reflects visible light and transmits infrared rays to prevent heating of the constituent members of the projector 32 by sunlight incident from the windshield glass.
  • the concave mirror 40 is a known concave mirror (concave mirror) used in a HUD projector that magnifies and projects the projected light.
  • the projector 32 in the illustrated example uses the mirror 38 and the concave mirror 40 as members for changing the optical path of the projected light, but the present invention is not limited thereto.
  • the projector 32 may have only one of the mirror 38 and the concave mirror 40, or in addition to or in addition to the mirror 38 and / or the concave mirror 40, another light reflecting element such as a free-form curved mirror may be used. You may have one or more. That is, the projector constituting the HUD of the present invention can be configured using various light reflecting elements.
  • the p-polarized light projected by the projector 32 and transmitted through the transmission window 46 passes through the first glass 12 and the interlayer film 16 and is incident on the polarization conversion layer 24.
  • the polarization conversion layer 24 is a layer in which the spirally oriented structure of the liquid crystal compound is fixed, and converts p-polarized light into circularly polarized light in the turning direction reflected by the cholesteric liquid crystal layer of the reflection layer 18.
  • green light and blue light are reflected by the green-blue reflection cholesteric liquid crystal layer 18GB, and red light is reflected by the red reflection cholesteric liquid crystal layer 18R.
  • the circularly polarized light projected by the reflection layer 18 is incident on the polarization conversion layer 24 again, and is converted into p-polarized light by the polarization conversion layer 24.
  • the projected light converted into p-polarized light by the polarization conversion layer 24 is applied to the observation position by the driver D.
  • the projected image is p-polarized, as described above, the projected image can be properly observed even when the driver D is wearing polarized sunglasses.
  • the s-polarized light when s-polarized light that becomes glaring, such as reflected light from a puddle and reflected light from a bonnet, is incident from outside the vehicle, the s-polarized light may be applied to the second glass 14, the heat seal layer 20, and the transparent base material 26. It is transmitted and incident on the retardation layer 28. The glaring s-polarized light incident on the retardation layer 28 is converted into elliptically polarized light in the swirling direction according to the s-polarized light due to the phase difference of the retardation layer 28.
  • the elliptically polarized light that has passed through the retardation layer 28 is then incident on the reflective layer 18, that is, the cholesteric liquid crystal layer, is transmitted, and is converted into circularly polarized light in the swirling direction corresponding to s-polarized light.
  • This circularly polarized light is then converted into s-polarized light by passing through the polarization conversion layer 24 and passes through the windshield glass 10. That is, in the windshield glass 10 of the present invention, the glaring s-polarized light that has entered from the outside of the windshield glass is transmitted as s-polarized light, so that it can be shielded by polarized sunglasses. Therefore, according to the windshield glass 10 of the present invention, it is possible to realize good suitability for polarized sunglasses against external light in a HUD that projects p-polarized light.
  • the windshield glass 10 of the present invention has a polarization conversion layer 24 in which the spiral orientation structure of the liquid crystal compound is fixed inside the reflective layer 18, that is, the cholesteric liquid crystal layer. Therefore, as will be shown later in the examples, the s-polarized light that does not have the retardation layer 28 and becomes glaring is incident from the outside of the vehicle and passes through the reflective layer 18, that is, the cholesteric liquid crystal layer to the external light containing the p-polarized light component. Even so, the polarization conversion layer 24 can return the p-polarized light component to s-polarized light.
  • the windshield glass 10 of the present invention can transmit s-polarized light, which is glaring, as it is, even if it does not have the retardation layer 28, so that it can be shielded by polarized sunglasses and is good against external light.
  • Polarized sunglasses suitability can be obtained.
  • the present invention is not limited to the above-described embodiment, and various improvements and changes may be made without departing from the gist of the present invention. Of course, it's good.
  • compositions 1 and 2 for forming a cholesteric liquid crystal layer The composition 1 for forming a cholesteric liquid crystal layer forming a cholesteric liquid crystal layer having a selective reflection center wavelength of 550 nm and the composition 2 for forming a cholesteric liquid crystal layer forming a cholesteric liquid crystal layer having a selective reflection center wavelength of 800 nm are as follows. The components of the above were mixed to prepare a composition for forming a cholesteric liquid crystal layer having the following composition.
  • composition 1 for forming a cholesteric liquid crystal layer and the composition 2 for forming a cholesteric liquid crystal layer a single-layer cholesteric liquid crystal layer having a film thickness of 3 ⁇ m is formed on a temporary support in the same manner as in the production of the half mirror film shown below. It was prepared and the reflection characteristics of visible light were confirmed. As a result, all of the produced cholesteric liquid crystal layers are right-handed circularly polarized light reflecting layers, and the selective reflection center wavelength (center wavelength) is such that the cholesteric liquid crystal layer according to the cholesteric liquid crystal layer forming composition 1 has a wavelength of 550 nm and is used for forming the cholesteric liquid crystal layer.
  • the cholesteric liquid crystal layer according to the composition 2 had a wavelength of 800 nm.
  • composition for forming a polarization conversion layer The following components were mixed to prepare a composition for forming a polarization conversion layer having the following composition.
  • ⁇ Mixture 1 100 parts by mass ⁇ Fluorine-based horizontal alignment agent 1 (Orientation control agent 1) 0.05 parts by mass ⁇ Fluorine-based horizontal alignment agent 2 (Orientation control agent 2) 0.02 parts by mass ⁇
  • Right-turning chiral agent LC756 Adjusted and polymerized initiator IRGACURE OXE01 (manufactured by BASF) according to the target number of pitches and the reflection wavelength that matches the film thickness.
  • a composition for forming a polarization conversion layer is prepared so that a desired selective reflection center wavelength ⁇ is obtained when a cholesteric liquid crystal layer is formed by adjusting the prescribed amount of the right-handed chiral agent LC756 having the above composition composition. bottom.
  • the selective reflection center wavelength ⁇ was determined by preparing a single-layer cholesteric liquid crystal layer having a film thickness of 3 ⁇ m on the temporary support and measuring by FTIR (Spectrum Two, manufactured by PerkinElmer).
  • the film thickness d of the spirally oriented structure can be expressed by "pitch P of the spirally oriented structure x number of pitches".
  • the pitch P of the spirally oriented structure is the length of one pitch in the spirally oriented structure, and the spirally oriented liquid crystal compound rotates 360 ° at one pitch.
  • a polyethylene terephthalate film having a thickness of 100 ⁇ m (Cosmo Shine A4100 manufactured by Toyobo Co., Ltd.) was prepared.
  • a rubbing treatment (rayon cloth, pressure: 0.1 kgf (0.98N), rotation speed: 1000 rpm (revolutions per minute), transport speed: 10 m / min, number of times: 1 reciprocation) was performed on one surface of the temporary support.
  • the composition 1 for forming a cholesteric liquid crystal layer is applied to the rubbing-treated surface of the temporary support at room temperature using a wire bar so that the thickness of the dry film after drying becomes 0.8 ⁇ m to obtain a coating layer.
  • rice field. The coating layer was dried at room temperature for 30 seconds and then heated in an atmosphere of 85 ° C. for 2 minutes. After that, in an environment with an oxygen concentration of 1000 ppm or less, the cholesteric liquid crystal phase was fixed by irradiating ultraviolet rays at 60 ° C. with a D valve (90 mW / cm 2 lamp) manufactured by Fusion Co., Ltd. for 6 to 12 seconds at an output of 60%. , A cholesteric liquid crystal layer having a thickness of 0.8 ⁇ m was obtained.
  • This cholesteric liquid crystal layer is a red-reflecting cholesteric liquid crystal layer that selectively reflects red light.
  • the same process was repeated using the cholesteric liquid crystal layer forming composition 2 on the surface of the obtained cholesteric liquid crystal layer, and the layer of the cholesteric liquid crystal layer forming composition 2 having a thickness of 0.55 ⁇ m was laminated. ..
  • This cholesteric liquid crystal layer is a green reflective cholesteric liquid crystal layer that selectively reflects green light.
  • a composition for forming a polarization conversion layer was applied to the surface of the formed cholesteric liquid crystal layer so as to have a film thickness of 2.2 ⁇ m to form a polarization conversion layer.
  • the polarization conversion layer was formed in the same manner as the cholesteric liquid crystal layer described above.
  • the number of pitches of the formed polarization conversion layer was 0.4.
  • this polarization conversion layer has a selective reflection center wavelength (reflection center wavelength) of 8580 nm when it is used as a cholesteric liquid crystal layer.
  • the refractive index of the polarization conversion layer which is a liquid crystal layer, is about 1.56. Therefore, "(1560 x y) / x" substantially coincides with the selective reflection center wavelength.
  • a half mirror film with a temporary support having a reflection layer having two cholesteric liquid crystal layers and a polarization conversion layer was obtained.
  • a reflection spectrum of the half mirror film with the temporary support was measured with a spectrophotometer (manufactured by JASCO Corporation, V-670), a reflection spectrum having a selective reflection center wavelength (center wavelength) at a wavelength of 550 nm and a wavelength of 800 nm was obtained.
  • a spectrophotometer manufactured by JASCO Corporation, V-670
  • a glass plate manufactured by Central Glass Co., Ltd., FL2, 300 ⁇ 300 mm, thickness 2 mm was prepared.
  • the first glass was obtained by bending this glass plate into curved glass having a radius of curvature of 1500 mm.
  • a half mirror film with a temporary support cut to the same size was laminated on the interlayer film with the polarization conversion layer on the interlayer film side. Then, the temporary support was peeled off from the half mirror film.
  • a glass plate (manufactured by Central Glass Co., Ltd., FL2, visible light transmittance 90%) having a length of 300 mm, a width of 300 mm, and a thickness of 2 mm was laminated on the half mirror film.
  • This laminate was held at 90 ° C. and 10 kPa (0.1 atm) for 1 hour, and then heated in an autoclave (manufactured by Kurihara Seisakusho) at 115 ° C. and 1.3 MPa (13 atm) for 20 minutes to remove air bubbles.
  • Windshield glass was made.
  • This windshield glass has a layer structure of "second glass / reflective layer / polarization conversion layer / interlayer film / first glass".
  • Example 2 Composition for forming a retardation layer
  • the following components were mixed to prepare a composition for forming a retardation layer having the following composition.
  • ⁇ Mixture 1 100 parts by mass ⁇ Fluorine-based horizontal alignment agent 1 (orientation control agent 1) 0.05 parts by mass ⁇ Fluorine-based horizontal alignment agent 2 (orientation control agent 2) 0.01 parts by mass ⁇ Polymerization initiator IRGACURE OXE01 (BASF) Made by the company) 1.0 part by mass ⁇ Solvent (methyl ethyl ketone) Amount that makes the solute concentration 20% by mass
  • Example 2 (Making half mirror film) A temporary support similar to that of Example 1 was prepared, and a rubbing treatment was performed in the same manner as in Example 1.
  • the angle ⁇ formed by the rubbing direction Sa and the long side direction H is 35 ° clockwise with reference to the long side direction H of the temporary support S. went.
  • the composition for forming a retardation layer was applied to the rubbing-treated surface of the temporary support using a wire bar, and then dried. Next, it was placed on a hot plate at 50 ° C. and irradiated with ultraviolet rays for 6 seconds with an electrodeless lamp "D bulb" (60 mW / cm 2 ) manufactured by Fusion UV Systems in an environment with an oxygen concentration of 1000 ppm or less, and the liquid crystal phase was changed. Fixed. As a result, a retardation layer having a thickness adjusted so as to obtain a desired front retardation, that is, a desired front retardation was obtained. The retardation of the formed retardation layer was measured by AxoScan and found to be 110 nm.
  • a cholesteric liquid crystal layer and a polarization conversion layer are formed on the surface of the retardation layer as in Example 1, and a temporary support having a retardation layer, a reflection layer having two cholesteric liquid crystal layers, and a polarization conversion layer.
  • a half mirror film with a body was obtained.
  • windshield glass (Making windshield glass) Using this half mirror film with a temporary support, windshield glass was produced in the same manner as in Example 1.
  • the windshield glass was regarded as a vertical direction with the long side direction H as the vertical direction.
  • This windshield glass has a layer structure of "second glass / retardation layer / reflection layer / polarization conversion layer / interlayer film / first glass".
  • Example 3 In the preparation of the composition for forming the polarization conversion layer, the prescription amount of the right-handed chiral agent LC756 was adjusted so that the selective reflection center wavelength (reflection center wavelength) when the cholesteric liquid crystal layer was formed was 7800 nm.
  • a half mirror film with a temporary support was produced in the same manner as in Example 2 except that this composition for forming a polarization conversion layer was used and the film thickness of the polarization conversion layer was changed to 1.1 ⁇ m. The number of pitches of the polarization conversion layer was 0.22.
  • a windshield glass was produced in the same manner as in Example 1. This windshield glass has a layer structure of "second glass / retardation layer / reflection layer / polarization conversion layer / interlayer film / first glass".
  • Example 4 (Saponification of cellulose acylate film) A 40 ⁇ m-thick cellulose acylate film (TAC) was prepared by the same production method as in Example 20 of International Publication No. 2014/112575. UV-531 manufactured by Teisei Kako Co., Ltd. was added to this cellulose acylate film as an ultraviolet absorber. The amount added was 3 phr (per hundred resin). The produced cellulose acylate film was passed through a dielectric heating roll having a temperature of 60 ° C., and the film surface temperature was raised to 40 ° C.
  • TAC ⁇ m-thick cellulose acylate film
  • an alkaline solution having the composition shown below was applied to one side of the film using a bar coater at a coating amount of 14 mL / m 2 , and heated to 110 ° C. under a steam-type far-infrared heater (manufactured by Noritake Company Limited). Was allowed to stay for 10 seconds. Then, using the same bar coater, 3 mL / m 2 of pure water was applied. Next, washing with water with a fountain coater and draining with an air knife were repeated three times, and then the film was allowed to stay in a drying zone at 70 ° C. for 5 seconds to be dried to prepare a saponified cellulose acylate film. The in-plane retardation of the saponified cellulose acylate film was measured by AxoScan and found to be 1 nm.
  • composition for forming an alignment film having the composition shown below was applied to the saponified surface of the saponified cellulose acylate film at 24 mL / m 2 with a wire bar coater, and dried with warm air at 100 ° C. for 120 seconds.
  • This half mirror film is a half mirror film with a transparent base material having a retardation layer, a reflection layer including two cholesteric liquid crystal layers, and a polarization conversion layer.
  • windshield glass was produced in the same manner as in Example 1. However, in this example, the transparent substrate was not peeled off.
  • This windshield glass has a layer structure of "second glass / transparent base material / retardation layer / reflective layer / polarization conversion layer / interlayer film / first glass".
  • Example 5 In order to form the heat seal layer, the following components were mixed to prepare a coating liquid for forming the heat seal layer.
  • a windshield glass was produced in the same manner as in Example 1 except that a half mirror film with a transparent base material having a heat seal layer was used.
  • This windshield glass has a layer structure of "second glass / heat seal layer / transparent base material / retardation layer / reflection layer / polarization conversion layer / interlayer film / first glass".
  • Example 1 (Making half mirror film) A transparent base material similar to that in Example 4 was prepared and subjected to a rubbing treatment. However, as conceptually shown in FIG. 3, the rubbing process was performed so that the angle ⁇ formed by the rubbing direction Sa and the long side direction H was 50 ° clockwise. A retardation layer and a reflective layer were formed on the rubbing-treated surface of the transparent base material in the same manner as in Example 2 to prepare a half mirror film with a transparent base material. However, by adjusting the thickness of the retardation layer, the front retardation was adjusted to 142 nm.
  • Example 7 (Making windshield glass) A heat seal layer was formed on the transparent base material of the half mirror film with the transparent base material in the same manner as in Example 5. A half mirror film with a transparent base material was laminated on the surface of the first glass in the same manner as in Example 1 with the heat seal layer facing. The same interlayer film as in Example 1 was laminated on the reflective layer of the half mirror film, and the second glass similar to Example 1 was laminated on the interlayer film. Using this laminate, a windshield glass was produced in the same manner as in Example 1. This windshield glass has a layer structure of "second glass / interlayer film / reflective layer / retardation layer / transparent base material / heat seal layer / first glass".
  • Comparative Example 2 A half mirror film with a transparent substrate was produced in the same manner as in Comparative Example 1 except that it did not have a retardation layer. Using this half mirror film, a windshield glass was produced in the same manner as in Comparative Example 1. This windshield glass has a layer structure of "second glass / interlayer film / reflective layer / transparent base material / heat seal layer / first glass".
  • Example 3 (Making half mirror film) A transparent base material similar to that in Example 4 was prepared and subjected to a rubbing treatment. However, as conceptually shown in FIG. 3, the rubbing process was performed so that the angle ⁇ formed by the rubbing direction Sa and the long side direction H was -50 ° clockwise. A retardation layer and a reflective layer were formed on the rubbing-treated surface of the transparent base material in the same manner as in Example 2 to prepare a half mirror film with the transparent base material. However, the thickness of the retardation layer was adjusted so that the front retardation was 310 nm.
  • Example 1 (Making windshield glass) The same interlayer film as in Example 1 was laminated on the same first glass as in Example 1. A half mirror film with a transparent substrate was laminated on the interlayer film with the transparent substrate facing the interlayer film. A heat seal layer similar to that of Example 5 was formed on the reflective layer of the half mirror film with a transparent base material, and a second glass similar to that of Example 1 was laminated on the heat seal layer. Using this laminated body, a windshield glass was produced in the same manner as in Example 1. This windshield glass has a layer structure of "second glass / heat seal layer / reflective layer / retardation layer / transparent base material / interlayer film / first glass".
  • the number of pitches of the polarization conversion layer was 0.8 (Comparative Example 4), 0.6864 (Comparative Example 5), and 0.0858 (Comparative Example 6).
  • a windshield glass was produced in the same manner as in Example 1.
  • These windshield glasses have a layer structure of "second glass / heat seal layer / transparent base material / retardation layer / reflective layer / polarization conversion layer / interlayer film / first glass".
  • the produced windshield glass was evaluated for its suitability for polarized sunglasses against external light, light resistance, impact resistance, and p-polarized reflectance.
  • the s-polarized light is incident from the second glass side in the direction of 65 ° with respect to the normal direction of the glass, and the p-polarized light of the transmitted light is transmitted from the first glass side by a spectrophotometer (V-670 manufactured by Nippon Spectroscopy Co., Ltd.). The rate spectrum was measured. At this time, a linear polarizing plate was placed on the light receiving portion of the spectrophotometer so that the vertical direction of the windshield glass and the transmission axis of p-polarized light incident on the spectrophotometer were parallel.
  • the visible light transmittance was calculated by multiplying the coefficient corresponding to the luminosity factor and the emission spectrum of the D65 light source at wavelengths of every 10 nm from 380 to 780 nm, and evaluated as the suitability for polarized sunglasses for external light.
  • the evaluation was performed according to the following evaluation criteria. A + less than 2% A 2% or more and less than 3% B 3% or more and less than 5% C 5% or more
  • the produced windshield glass was cut into a size of 50 mm ⁇ 50 mm.
  • Light resistance test based on JIS R 3212 using a super xenon weather meter (manufactured by Suga Test Instruments Co., Ltd.) on the cut windshield glass (internal temperature: 45 ° C, distance between light source and sample: 230 mm, UV irradiation amount 750 W) was carried out for 1000 hours.
  • the evaluation was performed according to the following evaluation criteria. A Decrease in transmittance is less than 2% (no change in reflected color) B Decrease in transmittance is 2% or more (reflection color is yellow compared to those without light resistance)
  • the produced windshield glass was subjected to a ball drop test based on JIS R 3212. Specifically, a steel ball (227 g, diameter 38 mm) was dropped from a height of 9 m on a windshield glass cooled at ⁇ 20 ° C., and the amount of glass dropped was measured. The evaluation was performed according to the following evaluation criteria. A Glass fall amount is less than 10g B Glass fall amount is 10g or more and less than 15g C Glass fall amount is 15g or more
  • the projected image reflectance was calculated by multiplying the reflectance by a coefficient corresponding to the visual sensitivity and the emission spectrum of the D65 light source at wavelengths of every 10 nm from 380 to 780 nm, and evaluated as brightness.
  • the evaluation was performed according to the following evaluation criteria. A 25% or more (The image looks good with the HUD's p-polarized light reflection system.) B 20% or more and less than 25% (Image can be seen with HUD's p-polarized light reflection system) The results are shown in Table 1 below.
  • the windshield glass of the present invention has good suitability for polarized sunglasses with respect to external light, and also has high p-polarized reflectance. That is, according to the HUD of the present invention using the windshield glass of the present invention, even when the driver wears polarized sunglasses, the projected image of the HUD can be observed, and the HUD is glaringly incident from the outside of the vehicle. Polarized light can be sufficiently shielded by polarized sunglasses.
  • Comparative Examples 1 to 3 having no polarization conversion layer as well as in Comparative Example 4 in which the thickness y of the polarization conversion layer exceeds 3 ⁇ m even if the polarization conversion layer is provided, “ Comparative Example 5 in which (1560 * y) / x ”is less than 3000 and Comparative Example 6 in which the number of pitches x of the polarization conversion layer is less than 0.1 are poor in sunglasses suitability.
  • Example 1 As shown in Comparative Example 2, the polarization conversion layer with a fixed helically oriented structures of the liquid crystal compounds conventionally p polarization projection retardation layer used in the HUD for irradiating light equivalent Performance can change p-polarized light to circularly polarized light.
  • Comparative Example 1 and Comparative Example 3 according to the windshield glass of the present invention, which converts p-polarized light into circularly polarized light with a polarization conversion layer in which the spirally oriented structure of the liquid crystal compound is fixed.
  • Comparative Example 1 which is a conventional windshield glass that converts p-polarized light into circularly polarized light in a retardation layer, excellent suitability for polarized sunglasses against external light can be obtained.
  • Comparative Example 1 and Comparative Example 2 by providing the interlayer film adjacent to the first glass inside the vehicle, excellent impact resistance can be obtained.
  • Example 2 by providing a retardation layer between the reflective layer (cholesteric liquid crystal layer) and the second glass on the outside of the vehicle, more excellent sunglasses suitability for external light can be obtained.
  • the number of pitches x of the polarization conversion layer is in the range of 0.2 to 0.8
  • the film thickness y is in the range of 0.6 to 2.0 ⁇ m
  • (1560 * y) / x By setting the value in the range of 6000 to 10000, it is possible to obtain better suitability for sunglasses against external light as well.
  • an excellent light resistance can be obtained by providing a transparent base material and adding an ultraviolet absorber to the transparent base material. From the above results, the effect of the present invention is clear.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Transportation (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Instrument Panels (AREA)
  • Laminated Bodies (AREA)
  • Eyeglasses (AREA)
  • Overhead Projectors And Projection Screens (AREA)
  • Polarising Elements (AREA)
  • Projection Apparatus (AREA)
  • Joining Of Glass To Other Materials (AREA)
PCT/JP2021/012159 2020-03-30 2021-03-24 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 Ceased WO2021200433A1 (ja)

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WO2023200018A1 (ja) * 2022-04-15 2023-10-19 富士フイルム株式会社 反射フィルム、積層体、ウインドシールドガラス、画像表示システム
EP4483232A4 (en) * 2022-02-23 2025-06-11 Spectralics Ltd. EFFECTIVE, GHOST-FREE REFLECTOR USING P-POLARIZATION

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JP2018116308A (ja) * 2018-04-06 2018-07-26 富士フイルム株式会社 遮熱用途に使用可能な反射部材および反射部材を含むプロジェクター
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WO2020184714A1 (ja) * 2019-03-13 2020-09-17 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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WO2019035358A1 (ja) * 2017-08-15 2019-02-21 富士フイルム株式会社 車両用ミラー、車両用画像表示機能付きミラー
JP2018116308A (ja) * 2018-04-06 2018-07-26 富士フイルム株式会社 遮熱用途に使用可能な反射部材および反射部材を含むプロジェクター
WO2020080355A1 (ja) * 2018-10-17 2020-04-23 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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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP4483232A4 (en) * 2022-02-23 2025-06-11 Spectralics Ltd. EFFECTIVE, GHOST-FREE REFLECTOR USING P-POLARIZATION
WO2023200018A1 (ja) * 2022-04-15 2023-10-19 富士フイルム株式会社 反射フィルム、積層体、ウインドシールドガラス、画像表示システム

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