JP2017181915A - Optical film for glass laminate and glass laminate using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a glass laminate that is free of double reflection of a display image, has no angle dependence of reflected light, and can be adapted to a windshield type head-up display.SOLUTION: A glass laminate according to the present invention comprises a first glass substrate, a first intermediate film, an optical film, a second intermediate film, and a second glass substrate in this order. The optical film comprises a transparent base material and a cholesteric liquid crystal polymer layer formed on the transparent base material, and the cholesteric liquid crystal polymer layer includes a light-absorptive compound. Here, when light is made incident from the side of the first glass substrate, R1/R2 is 0.9-1.3, where R1 is the total reflection coefficient of a reflection coefficient of the incident light outside an outer surface of the first glass substrate and a reflection coefficient of the incident light inside an outer surface of the second glass substrate, and R2 is the reflection coefficient of the incident light only outside the outer surface of the first glass substrate.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a laminated glass for windshield, which can also be used as an information display panel, and an optical film for laminated glass used therefor.

  Along with the expansion of safe driving support systems for automobiles, the mounting of head-up displays on automobiles has been accelerated for the purpose of quickly capturing various information with little eye movement while driving and supporting safe driving. Conventionally, as a method of displaying various information as a display image for the driver, a method of providing a transparent plate-like member for displaying an image in front of the driver's seat (for example, Patent Document 1), and displaying on the laminated glass for the windshield itself A method for projecting an image (for example, Patent Document 2) has been proposed. In addition, a projection system that includes a projection display member in which a cholesteric liquid crystal layer is fixed and can be used for a head-up display has also been proposed (for example, Patent Document 3).

JP, 2015-018099, A Japanese National Publication No. 4-502525 JP, 2015-141318, A

  In the method of Patent Document 1, since the optical characteristics of the transparent plate member can be arbitrarily adjusted, the double reflection of the display image can be suppressed, but the plate member is attached in front of the driver side. There is a problem that the line of sight is moved when the driver checks the display image.

  In addition, in the method of Patent Document 2, although there is almost no line of sight movement when the driver confirms the display image, a double image in which the image looks double due to the influence of the refractive index on the two glasses is generated. The wedge shape of the interlayer film eliminates the optical path length deviation and suppresses double reflection. However, this method of eliminating the optical path length deviation prevents double reflection depending on the position of the viewer's line of sight. There is a problem that there is a line of sight position that can be prevented and a line of sight position that cannot prevent double reflection.

  Furthermore, in the method of Patent Document 3, the cholesteric liquid crystal layer can selectively reflect light having a wavelength corresponding to the helical pitch of the liquid crystal and can be applied as a projection system, but the reflection wavelength is shifted depending on the viewing angle. Angle dependence of reflectivity may occur. In addition, when a display image is projected as a laminated glass formed by sandwiching a film having the cholesteric liquid crystal layer fixed between two interlayer films and sandwiching them between two sheets of glass, a double image in which the image appears double There was a problem that occurred.

  The present invention solves the above-mentioned problem, and provides a laminated glass applicable to a windshield type head-up display that can prevent double reflection regardless of the position of the viewer's line of sight and has no angle dependency. Is.

  The optical film for laminated glass of the present invention is an optical film for laminated glass comprising a transparent substrate and a cholesteric liquid crystal polymer layer formed on the transparent substrate, and the cholesteric liquid crystal polymer layer absorbs light. It is characterized by including a sex compound.

  Moreover, the laminated glass of the present invention is a laminated glass including a first glass substrate, a first intermediate film, an optical film, a second intermediate film, and a second glass substrate in this order, The optical film includes a transparent base material and a cholesteric liquid crystal polymer layer formed on the transparent base material, the cholesteric liquid crystal polymer layer includes a light absorbing compound, and the first glass substrate side. The reflection of the incident light reflectance outside the outer surface of the first glass substrate and the reflectance of the incident light inside the outer surface of the second glass substrate when light is incident from R1 / R2 is 0.9 to 1.3, where R1 is a rate and R2 is a reflectance of incident light only outside the outer surface of the first glass substrate.

  ADVANTAGE OF THE INVENTION According to this invention, the laminated glass which can be applied to the windshield type head up display without a double image in a display image and the angle dependence of reflected light can be provided.

FIG. 1 is a schematic cross-sectional view showing an example of the optical film for laminated glass of the present invention. FIG. 2 is a schematic cross-sectional view showing an example of the laminated glass of the present invention.

(Optical film for laminated glass of the present invention)
The optical film for laminated glass of the present invention comprises a transparent substrate and a cholesteric liquid crystal polymer layer formed on the transparent substrate, and the cholesteric liquid crystal polymer layer contains a light-absorbing compound. To do.

  Since the optical film for laminated glass of the present invention includes a cholesteric liquid crystal polymer layer containing a light-absorbing compound, it can absorb certain visible light. In addition, the cholesteric liquid crystal polymer layer containing the light-absorbing compound suppresses the angle dependency of the reflectance. For this reason, when the above laminated glass optical film is incorporated into laminated glass, it is possible to prevent double reflection of the displayed image and realize laminated glass applicable to windshield type head-up display without angle dependency it can. This will be described in detail in the description of the laminated glass of the present invention.

  Specifically, a resin layer is disposed on both sides of the laminated glass optical film, a first glass substrate and a second glass substrate are disposed on both sides of the resin layer, and the first glass substrate side. When light is incident from the outside, the reflectance of the incident light on the outside of the outer surface of the first glass substrate and the reflectance of the incident light on the inside of the outer surface of the second glass substrate (back surface reflectance) R1 / R2 is 0.9 to 1.3, and more preferably 1. is R1, and R2 is the reflectance of incident light only outside the outer surface of the first glass substrate. It can be set to 0-1.3. That is, reflection (back surface reflection) of incident light on the inner side of the outer surface of the second glass substrate can be suppressed. This point will also be described in detail in the description of the laminated glass of the present invention.

  Hereinafter, the optical film for laminated glass of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic cross-sectional view showing an example of the optical film for laminated glass of the present invention. In FIG. 1, the optical film 10 for laminated glass of the present invention includes a transparent base material 11 and a cholesteric liquid crystal polymer layer 12 formed on the transparent base material 11. The cholesteric liquid crystal polymer layer contains a light absorbing compound.

<Transparent substrate>
As a transparent base material which comprises the optical film for laminated glasses of this invention, if it forms with the material which has translucency, it will not specifically limit. Examples of the transparent substrate include polyester resins (eg, polyethylene terephthalate, polyethylene naphthalate, etc.), polycarbonate resins, polyacrylate resins (eg, polymethyl methacrylate), alicyclic polyolefin resins, Polystyrene resin (for example, polystyrene, acrylonitrile / styrene copolymer (AS resin), etc.), polyvinyl chloride resin, polyvinyl acetate resin, polyethersulfone resin, cellulose resin (for example, diacetyl cellulose, triacetyl) Cellulose or the like) or a resin such as norbornene-based resin processed into a film or sheet can be used. Examples of methods for processing the resin into a film or sheet include an extrusion molding method, a calender molding method, a compression molding method, an injection molding method, a method in which the resin is dissolved in a solvent, and the like. You may add additives, such as antioxidant, a flame retardant, a heat-resistant agent, a ultraviolet absorber, a slipping agent, an antistatic agent, to the said resin. The thickness of the transparent substrate may be, for example, 10 to 500 μm.

<Cholesteric liquid crystal polymer layer>
The cholesteric liquid crystal polymer layer constituting the optical film for laminated glass of the present invention is formed by photopolymerizing a material containing a liquid crystal compound having a polymerizable functional group, a chiral agent having a polymerizable functional group, and a light absorbing compound. can do.

  A cholesteric liquid crystal polymer can be obtained by adding a small amount of an optically active compound (chiral agent) to a nematic liquid crystal compound that is a rod-like molecule. This cholesteric liquid crystal polymer has a layered structure in which nematic liquid crystal compounds are stacked several times. Within this layer, the nematic liquid crystal compounds are arranged in a certain direction, and the layers are stacked such that the arrangement direction of the liquid crystal compounds is spiral. Therefore, the cholesteric liquid crystal polymer can selectively reflect only light of a specific wavelength according to the helical pitch. Thereby, the optical film provided with the cholesteric liquid crystal polymer layer can be used as a reflective display.

  A normal cholesteric liquid crystal polymer is characterized in that the helical pitch changes with temperature, and the wavelength of reflected light changes. When a mixture containing a liquid crystal compound having a polymerizable functional group and a chiral agent having a polymerizable functional group is made uniform in a liquid crystal state and then irradiated with active energy rays such as ultraviolet rays while maintaining the liquid crystal state, It becomes possible to produce a layer containing a cholesteric liquid crystal polymer in which the alignment state of the liquid crystal compound is fixed semipermanently.

  The cholesteric liquid crystal polymer layer thus obtained can fix the reflection wavelength semipermanently without changing the wavelength of the light reflected by the temperature. In addition, since the cholesteric liquid crystal polymer layer has cholesteric liquid crystal optical rotation, when the rotation direction and wavelength of circularly polarized light are equal to the rotation direction of liquid crystal molecules and the helical pitch, the light is reflected without being transmitted. Normally, sunlight is synthesized from circularly polarized light of a right spiral and a left spiral. Therefore, a cholesteric liquid crystal polymer layer with a specific spiral pitch using a chiral agent with a right-handed optical rotation and a cholesteric liquid crystal polymer layer with a specific spiral pitch using a chiral agent with a left-handed optical rotation Can be made higher in reflectivity at the selective reflection wavelength.

  The thickness of the cholesteric liquid crystal polymer layer is preferably 1.5 times or more and 3.0 times or less of the wavelength (maximum reflectance wavelength) for maximum reflection of incident light, and is 1.7 times or more and 2.5 times the maximum reflectance wavelength. The following is more preferable. If the thickness of the cholesteric liquid crystal polymer layer is less than 1.5 times the maximum reflectance wavelength, it may be difficult to maintain the orientation of the cholesteric liquid crystal polymer layer, and the light reflectance may decrease. It tends to be difficult to apply to laminated glass for up-displays. In addition, if the thickness of the cholesteric liquid crystal polymer layer exceeds 3.0 times the maximum reflectance wavelength, the orientation and light reflectance of the cholesteric liquid crystal polymer layer become too large, making it a laminated glass for windshield head-up displays. When applied, the visible light transmittance tends to decrease. The thickness of the cholesteric liquid crystal polymer layer is, for example, 0.5 μm or more and 3.0 μm or less, preferably 0.8 μm or more and 1.5 μm or less.

  Hereinafter, the material for forming the cholesteric liquid crystal polymer layer will be described in detail.

[Liquid crystal compound having a polymerizable functional group]
For the formation of the cholesteric liquid crystal polymer layer, a liquid crystal compound having a polymerizable functional group is used. As the liquid crystal compound, for example, known compounds described in Chapter 8 of “Basics and Applications of Liquid Crystal” (Shinichi Matsumoto, Ryo Kakuda; Industrial Research Committee) can be used.

  Specific examples of the liquid crystal compound include, for example, JP2012-69997A, JP2012-168514A, JP2008-217011, International Publication WO95 / 22586, and JP2000-281629. JP-A-2001-233837, JP-T-2001-519317, JP-T-2002-533742, JP-A-2002-308832, JP-A-2002-265421, JP-A-2005-309255, Examples thereof include compounds described in JP-A-2005-263789, JP-A-2008-291218, JP-A-2008-242349, and the like.

  As the liquid crystal compound used for forming the cholesteric liquid crystal polymer layer, one kind may be used alone, or if used alone, the orientation of the cholesteric liquid crystal polymer layer is likely to be disturbed. A low melting point liquid crystal compound may be used in combination. In this case, the difference between the melting point of the high melting point liquid crystal compound and the melting point of the low melting point liquid crystal compound is preferably 15 ° C. or higher and 30 ° C. or lower, and more preferably 20 ° C. or higher and 30 ° C. or lower.

  When the high melting point liquid crystal compound and the low melting point liquid crystal compound are used in combination, the melting point of the high melting point liquid crystal compound is preferably equal to or higher than the glass transition temperature of the transparent substrate. When the melting point of the liquid crystal compound is low, the compatibility and solubility with a chiral agent and a solvent are excellent, but when the melting point is too low, the heat resistance of the produced optical film is poor. Therefore, it is preferable that at least the melting point of the high melting point liquid crystal compound is equal to or higher than the glass transition temperature of the transparent substrate.

  As a combination of the high melting point liquid crystal compound and the low melting point liquid crystal compound, commercially available products can be used. For example, “PLC7700” (trade name, melting point 90 ° C.) and “PLC8100” (trade name, manufactured by ADEKA) In combination with "PLC7700" (melting point 90 ° C) and "PLC7500" (trade name, melting point 65 ° C), "UCL-017A" (trade name, melting point 96 ° C) manufactured by DIC Corporation And “UCL-017” (trade name, melting point: 70 ° C.).

  When three or more kinds of liquid crystal compounds having a polymerizable functional group are used, those having the maximum melting point are designated as high melting point liquid crystal compounds, and those having the minimum melting point are designated as low melting point liquid crystal compounds.

  When two or more liquid crystal compounds having a polymerizable functional group are used in combination, it is preferable that the high melting point liquid crystal compound is contained in a total mass ratio of 90% by mass or less. When the ratio of the high-melting-point liquid crystal compound exceeds 90% by mass, the compatibility of the liquid crystal compound tends to be reduced. As a result, the orientation of the cholesteric liquid crystal polymer layer is partially disturbed, resulting in an increase in haze. There is a case.

[Chiral agent having a polymerizable functional group]
The chiral agent having a polymerizable functional group used for the formation of the cholesteric liquid crystal polymer layer is not particularly limited as long as it has good compatibility with the liquid crystal compound and can be dissolved in a solvent. In addition, a conventional chiral agent having a polymerizable functional group can be used.

  Specific examples of the chiral agent include, for example, International Publication No. WO 98/00428 pamphlet, JP-T 9-506088, JP-T 10-509726, JP 2000-44451, JP 2000-506873. Compounds described in JP-A No. 2003-66214, JP-A No. 2003-313187, US Pat. No. 6,468,444, and the like. Moreover, as such a chiral agent, a commercial item can be used, for example, “S101”, “R811”, “CB15” (trade name) manufactured by Merck; “PALIOCOLOR LC756” (product) manufactured by BASF Name); “CNL715”, “CNL716” (trade name) manufactured by ADEKA, and the like.

  The selective reflection wavelength of the cholesteric liquid crystal polymer layer can be controlled by adjusting the helical pitch. This helical pitch can be controlled by adjusting the blending amounts of the liquid crystal compound and the chiral agent. For example, when the concentration of the chiral agent is high, the twisting force of the spiral increases, so that the pitch of the spiral is reduced, and the selective reflection wavelength λ of the cholesteric liquid crystal polymer layer is shifted to the short wavelength side. Further, when the concentration of the chiral agent is low, the twisting force of the spiral is reduced, so that the pitch of the spiral is increased, and the selective reflection wavelength λ of the cholesteric liquid crystal polymer layer is shifted to the longer wavelength side. Therefore, the blending amount of the chiral agent is preferably 0.1 parts by mass or more and 10 parts by mass or less, and 0.2 parts by mass or more and 7.0 parts by mass with respect to 100 parts by mass in total of the liquid crystal compound and the chiral agent. Less than the mass part is more preferable. When the blending amount of the chiral agent is 0.1 parts by mass or more and 10 parts by mass or less, the selective reflection wavelength of the obtained cholesteric liquid crystal polymer layer can be controlled in the near infrared region.

  The selective reflection wavelength of the cholesteric liquid crystal polymer layer can be controlled by adjusting the blending amount of the chiral agent as described above. If this selective reflection wavelength is controlled in the near infrared region, an optical film having substantially no absorption in the visible light region, that is, in the visible light region can be obtained.

[Polyfunctional acrylate compound]
The cholesteric liquid crystal polymer layer may contain a polyfunctional acrylate compound. Any polyfunctional acrylate compound may be used as long as it has good compatibility with the liquid crystal compound and the chiral agent and does not disturb the orientation of the cholesteric liquid crystal polymer layer.

  The polyfunctional acrylate compound is used to improve the curability of a liquid crystal compound having a polymerizable functional group and a chiral agent having a polymerizable functional group, but added in such an amount that the orientation of the cholesteric liquid crystal polymer layer is not disturbed. Is done. Specifically, the content of the polyfunctional acrylate compound may be 0.5 parts by mass or more and 5 parts by mass or less with respect to 100 parts by mass in total of the liquid crystal compound and the chiral agent. It is not less than 3 parts by mass.

[Light Absorbing Compound]
As the light absorbing compound, a known light absorbing compound such as carbon black, graphene, carbon nanotube, iron oxide or the like can be used alone, or two or more kinds can be used in combination.

  The content of the light absorbing compound is 0.05 parts by mass or more and 2.0 parts by mass with respect to 100 parts by mass in total of the liquid crystal compound having the polymerizable functional group and the chiral agent having the polymerizable functional group. The following is preferable. When the content of the light-absorbing compound is less than 0.05 parts by mass, the angle dependency of the reflected light of the cholesteric liquid crystal polymer layer tends to occur, and the above-described back surface reflection occurs when incorporated in a laminated glass. As a result, a double reflection of the display image tends to occur. On the other hand, when the content of the light-absorbing compound exceeds 2.0 parts by mass, the back reflection when incorporated in the laminated glass is suppressed and the double reflection of the display image is eliminated, but the cholesteric liquid crystal polymer layer The visible light transmittance tends to decrease.

  The method for producing the optical film for laminated glass of the present invention is not particularly limited. For example, the liquid crystal compound having the polymerizable functional group, the chiral agent having the polymerizable functional group, the light absorbing compound, and the photopolymerization start. A coating solution for forming a cholesteric liquid crystal polymer layer containing an agent and a solvent, and applying the coating solution for forming a cholesteric liquid crystal polymer layer to the transparent substrate and drying the coating solution on the transparent substrate. A cholesteric liquid crystal polymer layer can be formed.

  The photopolymerization initiator and the solvent are not particularly limited, and those usually used in the field of optical films can be used.

<Laminated glass of the present invention>
The laminated glass of the present invention comprises a first glass substrate, a first intermediate film, an optical film, a second intermediate film, and a second glass substrate in this order, and the optical film comprises a transparent substrate. And a cholesteric liquid crystal polymer layer formed on the transparent base material, the cholesteric liquid crystal polymer layer including a light absorbing compound, when light is incident from the first glass substrate side And a reflectance that combines the reflectance of the incident light outside the outer surface of the first glass substrate and the reflectance of the incident light inside the outer surface of the second glass substrate (back surface reflectance). R1 / R2 is 0.9 to 1.3, where R1 is the reflectance of incident light only on the outside of the outer surface of the first glass substrate.

  The laminated glass of the present invention uses the above-described optical film for laminated glass of the present invention as the optical film. Since the optical film includes a cholesteric liquid crystal polymer layer containing a light-absorbing compound, it can absorb certain visible light. In addition, the cholesteric liquid crystal polymer layer containing the light-absorbing compound suppresses the angle dependency of the reflectance. For this reason, the laminated glass applicable to the windshield type head-up display which can prevent the double reflection of a display image and has no angle dependence is realizable.

  Specifically, the laminated glass of the present invention has a reflectance of incident light outside the outer surface of the first glass substrate when the light is incident from the side of the first glass substrate, and the first glass substrate. The reflectance that combines the reflectance (back surface reflectance) of incident light inside the outer surface of the glass substrate 2 is R1, and the reflectance of incident light only outside the outer surface of the first glass substrate is R2. Then, R1 / R2 can be set to 0.9 to 1.3, more preferably 1.0 to 1.3. That is, reflection of incident light (back surface reflection) on the inner side of the outer surface of the second glass substrate can be suppressed, so that it is possible to prevent the double reflection of the display image and there is no angle dependency. Laminated glass can be realized.

  The reason why double reflection can be prevented by the laminated glass of the present invention and the angle dependency can be reduced is not clear, but can be presumed as follows. That is, when the cholesteric liquid crystal polymer layer used in the optical film of the laminated glass of the present invention contains a light absorbing compound, incident light is absorbed by the light absorbing compound, and the light transmittance is reduced and the glass is returned from the back glass. It can be inferred that double reflection can be prevented because R1 / R2 is reduced by the absorbed light being similarly absorbed by the light absorbing compound. At the same time, since the light absorbing compound is contained in the cholesteric liquid crystal polymer layer, it can be inferred that the angle dependency can be reduced by reducing the light transmittance in the visible light region.

  Hereinafter, the laminated glass of this invention is demonstrated based on drawing.

  FIG. 2 is a schematic cross-sectional view showing an example of the laminated glass of the present invention. In FIG. 2, the laminated glass 20 of the present invention comprises a first glass substrate 22a, a first intermediate film 21a, an optical film 10, a second intermediate film 21b, and a second glass substrate 22b. In order. The optical film 10 includes a transparent substrate 11 and a cholesteric liquid crystal polymer layer 12 containing a light absorbing compound.

  In FIG. 2, when light is incident from the glass substrate 22b side, the reflectance of incident light on the outside of the outer surface of the glass substrate 22b and the reflectance of incident light on the inside of the outer surface of the glass substrate 22a R1 / R2 is 0.9 to 1.3, more preferably 1.0 to 1.R. where R1 is the reflectance of the incident light only on the outside of the outer surface of the glass substrate 22b. 3 is set.

  Moreover, it is preferable that the visible light transmittance | permeability measured based on JISR3211 of the laminated glass 20 is 70% or more. Thereby, the laminated glass of this invention can be used as a windshield.

<Optical film>
The optical film used in the laminated glass of the present invention is the above-described optical film for laminated glass of the present invention, and the description thereof is omitted.

<Intermediate film>
The intermediate film used in the present invention is formed from a transparent resin. The intermediate film functions as an adhesive layer for joining two glass substrates. Accordingly, the transparent resin forming the intermediate film is not particularly limited as long as it has adhesiveness. For example, a polyvinyl butyral resin, an ethylene-vinyl acetate copolymer resin, a polyvinyl acetal resin, or the like is used. it can.

  The intermediate film can contain various adjusting agents such as an ultraviolet absorber, an antioxidant, an antistatic agent, and a heat stabilizer.

  The thickness of the intermediate film is not particularly limited, but may be, for example, 0.05 to 3 mm in order to ensure transparency and penetration resistance when a laminated glass is used.

<Glass substrate>
The glass substrate used by this invention is not specifically limited, For example, a transparent glass substrate with a thickness of 1-3 mm can be used.

  Hereinafter, the present invention will be described in detail based on examples. However, the present invention is not limited to the following examples. In addition, unless otherwise indicated, in the following, “part” means “part by mass”.

Example 1
<Production of optical film>
First, as a transparent substrate, a polyethylene terephthalate (PET) film (trade name “QT92”, thickness: 50 μm, glass transition temperature: 75 ° C., manufactured by Toray Industries, Inc.) having one surface easily treated with an acrylic resin was prepared.

Next, after stirring and mixing the following materials, a dispersion treatment was performed with a sand mill to prepare a coating solution for forming a cholesteric liquid crystal polymer layer containing a light absorbing compound.
(1) Liquid crystal compound having a polymerizable functional group (BASF, trade name “LC-242”): 100 parts (2) Chiral compound having a polymerizable functional group (BASF, trade name “LC-756”) ): 4.43 parts (3) Light absorbing compound (carbon black, manufactured by Mitsubishi Chemical Corporation, trade name “# 2650”): 1.1 parts (4) Photopolymerization initiator (manufactured by Ciba Specialty Chemicals) Product name “Irgacure 907”): 3.0 parts (5) Solvent (cyclohexanone): 412 parts

Subsequently, the coating liquid for forming the cholesteric liquid crystal polymer layer is applied onto the surface of the PET film that has not been easily adhered with an acrylic resin using a micro gravure coater, and dried at 100 ° C. to form a coating film. did. The coating film was cured by irradiating the coating film with ultraviolet rays (maximum wavelength: 365 nm, light source: high-pressure mercury lamp, light amount: 500 mJ / cm ² ) for 30 seconds, and a cholesteric liquid crystal polymer layer (thickness: 1.0 μm) was formed, and the optical film of Example 1 was produced.

<Production of laminated glass>
First, two glass sheets with a thickness of 2 mm (manufactured by Nippon Sheet Glass Co., Ltd.) were prepared as glass substrates. Next, two transparent polyvinyl butyral (PVB) films having a thickness of 0.38 mm were prepared as intermediate films. Subsequently, the optical film prepared above was sandwiched between the two PVB films, and the two float glasses were overlapped on both sides of the PVB film to prepare a laminate. Thereafter, the laminate was wrapped in a rubber bag and vacuum deaerated for 10 minutes in an autoclave heated to 90 ° C. to pre-adhere each layer of the laminate. Subsequently, the pre-adhered laminate was cooled to room temperature, then removed from the rubber bag, and again heated and pressurized in an autoclave at 135 ° C. under a pressure of 12 kg / cm ² for 30 minutes to produce the laminated glass of Example 1. did.

(Example 2)
A laminated glass of Example 2 was produced in the same manner as in Example 1 except that the blending ratio of the light absorbing compound in the coating liquid for forming a cholesteric liquid crystal polymer layer was changed to 0.07 part.

(Example 3)
A laminated glass of Example 3 was produced in the same manner as in Example 1 except that the blending ratio of the light absorbing compound in the coating liquid for forming a cholesteric liquid crystal polymer layer was changed to 1.57 parts.

(Comparative Example 1)
A laminated glass of Comparative Example 1 was produced in the same manner as in Example 1 except that the light absorbing compound was not added to the coating solution for forming a cholesteric liquid crystal polymer layer.

(Comparative Example 2)
One transparent polyvinyl butyral (PVB) film having a thickness of 0.38 mm was sandwiched between two pieces of float glass (manufactured by Nippon Sheet Glass Co., Ltd.) having a thickness of 2 mm to produce a laminate. The optical film produced in Example 1 is not laminated on this laminate. A laminated glass of Comparative Example 2 was produced in the same manner as in Example 1 except that the above laminate was used.

  Next, the following characteristics were measured using the produced laminated glasses of Examples 1 to 3 and Comparative Examples 1 and 2.

<Ratio of reflectance R1 / R2>
First, when light is incident from one side of the glass substrate, the reflectance of the incident light on the outside of the outer surface of the glass substrate on the incident light side and the outer surface of the glass substrate on the opposite side to the incident light side The reflectance R1 combined with the reflectance of incident light on the inner side was measured in the wavelength range of 350 to 800 nm using an integrating sphere unit of a spectrophotometer (trade name “V-570” manufactured by JASCO Corporation). Next, the outside of the outer surface of the glass substrate on the side opposite to the incident light side was exposed with sand paper, then painted with oil-based black ink, and a black tape was further applied. In this state, the reflectance R2 of incident light only on the outside of the outer surface of the glass substrate on the incident light side was measured in the same manner as described above. Finally, the reflectance ratio R1 / R2 was calculated.

<Visible light transmittance, haze]
The visible light transmittance and haze of the entire laminated glass were measured using a haze meter “NDH-2000” (trade name) manufactured by Nippon Denshoku.

  Then, about the produced laminated glass of Examples 1-3 and Comparative Examples 1-2, the angle dependence of reflected light and the quality of a display image were evaluated as follows.

<Angle dependence of reflected light>
A spectral reflection spectrum from the front of the laminated glass, a spectral reflection spectrum at a position shifted by 30 ° to the right from the front, and a spectral reflection spectrum at a position shifted by 30 ° to the left are manufactured by Nippon Denshoku Industries Co., Ltd. The color difference ΔEab of the reflected color was calculated by measuring with a spectral variable color difference meter “GC5000” (trade name). A smaller ΔEab value indicates that the color of the reflected light is smaller and the angle dependency of the reflected light is less.

<Display image quality>
Display information light from a display unit installed on the lower side of the produced laminated glass is emitted with an incident angle of 60 ° with respect to the laminated glass, reflected by the display unit to display a display image, and displayed at a predetermined position. The presence or absence of multiple images was confirmed visually, and the quality of the display image was evaluated according to the following criteria.
Good: When a double image was not confirmed.
Bad: When a double image is confirmed.

  The results are shown in Table 1.

  From Table 1, it can be seen that the laminated glasses of Examples 1 to 3 of the present invention have little angle dependency of the reflected light and a good display image. On the other hand, in Comparative Example 1 in which no light absorbing compound was added to the cholesteric liquid crystal polymer layer of the optical film used for the laminated glass, the angle dependency of the reflected light was large, the display image was poor, and the laminated glass had an optical film. In Comparative Example 2 in which no was incorporated, the angle dependency of the reflected light was small, but the display image was poor.

  ADVANTAGE OF THE INVENTION According to this invention, the laminated glass which can be applied to the windshield type head up display without a double image in a display image and the angle dependence of reflected light can be provided.

DESCRIPTION OF SYMBOLS 10 Optical film for laminated glass 11 Transparent base material 12 Cholesteric liquid crystal polymer layer 20 Laminated glass 21a, b Intermediate film 22a, b Glass substrate

Claims (9)

An optical film for laminated glass comprising a transparent substrate and a cholesteric liquid crystal polymer layer formed on the transparent substrate,
The optical film for laminated glass, wherein the cholesteric liquid crystal polymer layer contains a light absorbing compound.   The optical film for laminated glass according to claim 1, wherein the light absorbing compound is at least one selected from the group consisting of carbon black, graphene, carbon nanotubes, and iron oxide. A resin layer is arranged on both sides of the optical film for laminated glass,
Arranging a first glass substrate and a second glass substrate on both sides of the resin layer;
When light is incident from the side of the first glass substrate, the reflectance of incident light on the outside of the outer surface of the first glass substrate and the incident light on the inside of the outer surface of the second glass substrate R1 / R2 is 0.9 to 1.3, where R1 is the total reflectance of the first glass substrate and R2 is the reflectance of incident light only outside the outer surface of the first glass substrate. Item 3. The optical film for laminated glass according to Item 1 or 2.   The optical film for laminated glass according to claim 3, wherein R1 / R2 is 1.0 to 1.3. A laminated glass including a first glass substrate, a first intermediate film, an optical film, a second intermediate film, and a second glass substrate in this order,
The optical film includes a transparent substrate and a cholesteric liquid crystal polymer layer formed on the transparent substrate,
The cholesteric liquid crystal polymer layer includes a light absorbing compound,
When light is incident from the side of the first glass substrate, the reflectance of incident light on the outside of the outer surface of the first glass substrate and the incident light on the inside of the outer surface of the second glass substrate R1 / R2 is 0.9 to 1.3, where R1 is the total reflectance of the first glass substrate and R2 is the reflectance of incident light only outside the outer surface of the first glass substrate. Laminated glass characterized by   The laminated glass according to claim 5, wherein R1 / R2 is 1.0 to 1.3.   The laminated glass according to claim 5 or 6, wherein the light absorbing compound is at least one selected from the group consisting of carbon black, graphene, carbon nanotube, and iron oxide.   The laminated glass according to claim 5, wherein the intermediate film is made of a transparent resin.   The laminated glass according to any one of claims 5 to 8, wherein the visible light transmittance measured in accordance with JIS R3211 is 70% or more.

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