WO2023080116A1 - Reflection film, windshield glass, head-up display system, and transport machine having said head-up display system - Google Patents

Abstract

Provided is a reflection film having at least a selective reflection layer in which the center wavelength of selective reflection with respect to light having an incidence angle of 60° satisfies (a), a selective reflection layer in which said center wavelength of selective reflection satisfies (b), and a selective reflection layer in which said center wavelength of selective reflection satisfies (c), and at least one fluorescent dye having a light emission peak separated at least 5 nm from each center wavelength of selective reflection of the selective reflection layers in the visible light region. (a) 400 nm to less than 500 nm; (b) 500 nm to less than 600 nm; (c) 600 nm to 700 nm.

Description

Reflective film, windshield glass, head-up display system, and transport machine with this head-up display system

The present invention relates to a reflective film, windshield glass, a head-up display system, and a transport machine having this head-up display system.

A head-up display (HUD) system projects an image onto the windshield glass of a vehicle, etc., and provides driving support information such as route guidance, driving speed, and warnings to the driver through the windshield glass. Are known.
With the HUD system, the observer can obtain various driving support information such as route guidance, driving speed, and vehicle status without significantly moving the line of sight or focus while looking at the external world in front of the vehicle. Stress-free driving becomes possible.
The basic configuration of the HUD is generally as follows. First, projected light from a projector incorporated in the dashboard is imaged as an intermediate image on the surface of an intermediate image screen (diffusion plate). This intermediate image is magnified by a concave mirror (magnifying glass), transmitted through a transmission window provided on the dashboard, reflected by a windshield glass with a built-in half mirror, and guided to the driver. A driver or the like recognizes this intermediate image ahead of the windshield glass as a so-called virtual image. That is, the driver or the like can perceive the driving support information as if it were floating on the road.

Various half-mirror films that can be used for head-up display systems have been proposed. For example, Patent Document 1 discloses a windshield glass including a projection image display portion, wherein the projection image display portion includes a circularly polarized light reflecting layer and a λ/2 retardation layer, and the circularly polarized light reflecting layer reflects cholesteric liquid crystal. 4 or more layers, one of the 4 or more cholesteric liquid crystal layers is a cholesteric liquid crystal layer having a selective reflection central wavelength of 350 nm or more and less than 490 nm, and the selective reflection of the 4 or more cholesteric liquid crystal layers is Windshield glasses are described whose central wavelengths are different from one another. According to Patent Document 1, it is possible to provide a windshield glass that has a transparent appearance when viewed from the direction perpendicular to the windshield glass and that does not lose its beauty even under external light. there is

JP 2018-81296 A

In HUD systems that incorporate a P-polarized reflective film into the windshield glass, in addition to the legal regulation that the transmittance of the windshield glass must be 70% or more, the clarity of the displayed image and the design can be viewed from various angles. It is required that the appearance color is transparent (white light looks white). In order to realize this, a laser with a narrow emission wavelength band is used as the light source of the imager, and as the selective reflection layer of the P-polarized reflective film, the half width of each reflected light is narrow as described in the above-mentioned Patent Document 1. It is conceivable to use a cholesteric liquid crystal reflective layer with high reflectance. By using the imager light source in combination with the selective reflection layer, the imager light can be selectively and efficiently reflected, and as a result, the image brightness ( (clearness of displayed image) can be improved, and furthermore, high transparency can be maintained with respect to appearance color.
However, as a result of repeated studies by the present inventors, when the above-mentioned cholesteric liquid crystal reflective layer with a narrow half-value width of reflected light and high reflectance is used, when observed from various angles, the blue shift of the reflection band occurs. It has been found that the color tone changes slightly depending on the viewing angle.

The present invention has at least three selective reflection layers corresponding to each region of blue light (B), green light (G), and red light (R) to support full-color display of the HUD system, while maintaining the appearance color. A reflective film that can sufficiently enhance the transparency of taste (can effectively suppress the expression of color), a windshield glass and a head-up display system using this reflective film, and these windshield glasses or An object of the present invention is to provide a transport aircraft with a head-up display system.

The above problems have been solved by the following means.
[1]
The selective reflection center wavelength for light with an incident angle of 60° is a selective reflection layer (I) having the following (a), a selective reflection layer (II) having the following (b), and a selective reflection having the following (c). having at least a layer (III) and
A reflective film containing at least one fluorescent dye having an emission peak in the visible light region separated by 5 nm or more from any of the selective reflection center wavelengths of the selective reflection layers (I) to (III).
(a) 400 nm or more and less than 500 nm (b) 500 nm or more and less than 600 nm (c) 600 nm or more and 700 nm or less [2]
The reflective film according to [1], having a layer (FL) containing the fluorescent dye and not functioning as a selective reflection layer.
[3]
The reflective film according to [2], wherein the layer (FL) is not arranged between two selective reflection layers.
[4]
The selective reflection layer (III) contains the fluorescent dye, or
A selective reflection layer other than the selective reflection layer (III) is arranged on one side of the selective reflection layer (III), and a layer (FL ), the reflective film according to [1].
[5]
The reflective film according to any one of [1] to [4], wherein at least one of the fluorescent dyes has an emission peak wavelength in the range of 450 nm or more and less than 550 nm.
[6]
The reflective film according to [5], which contains two or more of the above fluorescent dyes, and at least one of the fluorescent dyes has an emission peak wavelength outside the range of 450 nm or more and less than 550 nm.
[7]
The reflective film according to [5], which contains two or more of the above fluorescent dyes, and at least one of the fluorescent dyes has an emission peak wavelength in the range of 550 nm or more and 650 nm or less.
[8]
[1] to [ 7], the reflective film according to any one of the items.
[9]
The reflective film according to any one of [1] to [8], comprising at least one polarization conversion layer.
[10]
The reflective film according to any one of [1] to [9], wherein the selective reflection layers (I) to (III) are made of cholesteric liquid crystal.
[11]
The reflective film according to any one of [1] to [9], wherein the selective reflection layers (I) to (III) are formed by laminating an optically anisotropic layer and an optically isotropic layer.
[12]
A window having a first glass plate, a second glass plate, and the reflective film according to any one of [1] to [11] disposed between the first glass plate and the second glass plate. shield glass.
[13]
The windshield glass according to [12];
A head-up display system comprising: a projector that irradiates the windshield glass with p-polarized projection image light.
[14]
[13] A transport aircraft equipped with the head-up display system according to [13].

The reflective film of the present invention has at least three selective reflective layers corresponding to each region of RGB, and can sufficiently improve the transparency of the appearance color while supporting the full-color display of the HUD. Therefore, the windshield glass, the head-up display system, and the transportation machine using the reflective film of the present invention are excellent in the transparency of the appearance color regardless of the viewing angle.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram which shows roughly an example of the head-up display system of this invention. FIG. 2 is a schematic diagram showing one configuration example of a windshield glass having a linearly polarized light reflecting film containing a cholesteric liquid crystal layer, which is used in the head-up display system of the present invention. 1 is a cross-sectional view schematically showing one configuration example of a windshield glass having a linearly polarized light reflecting film made of a dielectric multilayer film, which is used in the head-up display system of the present invention; FIG. FIG. 4 is a schematic diagram showing the relationship of the refractive indices in the linearly polarized light reflective film when the windshield glass of FIG. 3 is viewed from the front.

In the present invention or in the specification, "-" indicating a numerical range includes the numerical values described on both sides. For example, when ε1 is a numerical value α1 to a numerical value β1, the range of ε1 is a range including the numerical value α1 and the numerical value β1.
In the present invention or the specification, angles such as "specific numerical angles", "parallel", "perpendicular" and "perpendicular" are generally accepted in the relevant technical field unless otherwise specified. including error bars. For example, it means being within a range of less than ±10° of the exact angle, and the error from the exact angle is preferably 7° or less, more preferably 5° or less. In addition, "same" includes the error range generally allowed in the relevant technical field, and "entire surface" and the like also include the error range generally allowed in the relevant technical field.

In this specification, the term "sense" for circularly polarized light means whether it is right-handed circularly polarized light or left-handed circularly polarized light. The sense of circular polarization is right circular polarization if the tip of the electric field vector rotates clockwise as time increases, and left if it rotates counterclockwise when viewed as if the light were traveling toward you. Defined as being circularly polarized.

In this specification, the term "sense" is sometimes used for the twist direction of the cholesteric liquid crystal spiral. When the helix direction (sense) of the cholesteric liquid crystal is right, it reflects right-handed circularly polarized light and transmits left-handed circularly polarized light. When the sense is left, it reflects left-handed circularly polarized light and transmits right-handed circularly polarized light.

In the present invention or in the specification, the term "light" means visible light and natural light (non-polarized light) or excitation light, unless otherwise specified.
Among electromagnetic waves, visible light is light with a wavelength that can be seen by the human eye, and usually indicates light in the wavelength range of 380 to 780 nm. Invisible light is light in the wavelength range below 380 nm or in the wavelength range above 780 nm.
In addition, although not limited to this, among visible light, light in the wavelength range of 420 to 490 nm is blue (B) light, and light in the wavelength range of 495 to 570 nm is green (G) light. , 600 nm or more and less than 700 nm is red (R) light. Furthermore, although not limited to this, infrared ray indicates a wavelength region of more than 780 nm and 2000 nm or less among invisible light.

In this specification, the "incidence angle n°" refers to the angle formed between the normal line of the windshield glass and the projected image light emitted from the projector (see FIG. 1), or the angle formed between the normal line and the excitation light. means Note that the above "n" is 0 or a positive real number.

In this specification, "visible light transmittance" shall be A light source visible light transmittance defined in JIS (Japanese Industrial Standards) R 3212:2015 (automobile safety glass test method). That is, with a spectrophotometer using A light source, the transmittance of each wavelength in the wavelength range of 380 to 780 nm is measured, and obtained from the wavelength distribution and wavelength interval of the CIE (International Commission on Illumination) light adaptation standard relative luminosity It is the transmittance obtained by multiplying the transmittance at each wavelength by the weighting factor obtained and taking a weighted average. Further, when simply referring to "reflected light" or "transmitted light", it is used in the sense of including scattered light and diffracted light.

In the present invention or the specification, p-polarized light means polarized light that oscillates in a direction parallel to the plane of incidence of light. The plane of incidence means the plane that is perpendicular to the reflective surface (such as the surface of the windshield glass) and that contains the incident light beam and the reflected light beam. In p-polarized light, the plane of oscillation of the electric field vector is parallel to the plane of incidence. On the other hand, s-polarized light means polarized light that oscillates in a direction perpendicular to the plane of incidence of light. For s-polarized light, the plane of oscillation of the electric field vector is perpendicular to the plane of incidence.

In this specification, the front retardation is a value measured using AxoScan manufactured by Axometrics. Unless otherwise specified, the measurement wavelength is 550 nm. The front retardation can also be measured by KOBRA21ADH or WR (manufactured by Oji Keisoku Kiki Co., Ltd.) by allowing light of a wavelength within the visible light wavelength range to enter in the normal direction of the film. When selecting the measurement wavelength, the wavelength selection filter can be manually replaced, or the measured value can be converted by a program or the like for measurement.

In this specification, the birefringence (Δn) of a liquid crystal compound is described on p. It is a value measured according to the method described in 214. Specifically, Δn at 60° C. can be obtained by injecting a liquid crystal compound into a wedge-shaped cell, irradiating the cell with light having a wavelength of 550 nm, and measuring the refraction angle of the transmitted light.

In the present specification, optical isotropy in the "optically isotropic layer" means not exhibiting birefringence. On the other hand, the optical anisotropy in the "optically anisotropic layer" means exhibiting birefringence _. and the refractive index n _o2 in the direction perpendicular to the in-plane slow axis direction (the in-plane fast axis direction) have a relationship of n _e1 >n _o2 .

As used herein, "projection image" means an image based on the projection of light from the projector used. The projected image is visually recognized by the observer as a virtual image that appears above the reflective film of the windshield glass.
As used herein, "screen image" means an image displayed on a rendering device of a projector or rendered by a rendering device, such as on an intermediate image screen. An image is a real image as opposed to a virtual image.
Both the image and the projected image may be a monochromatic image, a multicolor image of two or more colors, or a full color image.

In addition, in this specification, the term "liquid crystal compound" is used to include those that no longer exhibit liquid crystallinity due to a curing reaction or the like.

In this specification, the term "(meth)acrylate" is used to mean either acrylate or methacrylate, or both.

The HUD system of the present invention is typically used by being mounted on vehicles such as automobiles and trains, aircraft, and transport machines such as ships.

The head-up display system (hereinafter referred to as HUD system) of the present invention will be described in detail below based on preferred embodiments illustrated in the accompanying drawings. Note that the dimensions and scale of each part in the drawings may be different from the actual ones for convenience of explanation. Also, the drawings may be schematically shown for easy understanding.

<<Head-up display system (HUD system)>>
The HUD system of the present invention is a HUD system that includes a windshield glass having a reflective film and a projector that irradiates the windshield glass with p-polarized projection image light.

As will be described later, in the HUD system of the present invention, the reflective film includes a selective reflection layer (I) having a selective reflection central wavelength for light with an incident angle of 60 ° specified below (a) and a selective reflection layer (b) specified below. and a selective reflection layer (III) defined as (c) below,
At least one fluorescent dye having an emission peak in the visible region separated by 5 nm or more from any of the selective reflection center wavelengths of the selective reflection layers (I) to (III) is included.
Regulation (a) 400 nm or more and less than 500 nm Regulation (b) 500 nm or more and less than 600 nm Regulation (c) 600 nm or more and 700 nm or less

In the following description, the selective reflection center wavelengths of the selective reflection layer (I), the selective reflection layer (II), and the selective reflection layer (III) with respect to light with an incident angle of 60° are λ _B , λ _G , and λ _R , respectively. is sometimes called.
λ _B is preferably in the wavelength range of 430 to 470 nm, more preferably in the wavelength range of 440 to 460 nm.
λ _G is preferably in the wavelength range of 500-550 nm, more preferably in the wavelength range of 510-540 nm.
λ _R is preferably in the wavelength range of 600-650 nm, more preferably in the wavelength range of 610-640 nm.
The visible light region in which the emission peak wavelength of the fluorescent dye exists means a wavelength region of 380 to 780 nm.

In the _{HUD system} of the present invention, the reflective film is _a selective reflection layer (I ) to (III), and an emission peak separated by 5 nm or more from each of the selective reflection center wavelengths λ _B , λ _G , and λ _R of the selective reflection layers (I) to (III) in the visible light region By including at least one kind of fluorescent dye having the above-described fluorescent dye, the color tone in the visible light region other than λ _B , λ _G , and λ _R is compensated. Therefore, it is possible to adjust the balance of the light intensity in the visible region of the light after being reflected by the reflective film, to make the reflected color neutral, and to sufficiently improve the transparency of the appearance color.

In addition, as shown below, the HUD system of the present invention adjusts the transparency of the appearance color to the same level or higher than that of the conventional technology even for light with an incident angle of 5° or an angle around it. be able to. As will be described later, the selective reflection central wavelength λd when the light ray passes at an angle of θ2 with respect to the normal direction of the reflective film and the selective reflection central wavelength λ when θ2 is 0° are: λd= There is a relationship of λ×cos θ2.
Therefore, the selective reflection layers (I) to (III) having the selective reflection center wavelengths λ _B , λ _G , and λ _R in specific wavelength regions for light with an incident angle of 60° are equivalent to light with an incident angle of 5° The selective reflection center wavelengths for are in the following wavelength ranges, respectively.
Selective reflection layer (I): 445 nm or more and less than 560 nm Selective reflection layer (II): 560 nm or more and less than 670 nm Selective reflection layer (III): 670 nm or more and 790 nm or less In addition, the selective reflection center for light with an incident angle of 60°, which will be described later. A layer (UV layer) having a wavelength in the wavelength range of 300 nm or more and less than 400 nm also has a selective reflection central wavelength for light with an incident angle of 5° in the wavelength range of 335 nm or more and less than 445 nm.
Thus, a fluorescent dye having emission peaks in the visible light region separated by 5 nm or more from any of λ _B , λ _G , and λ _R can be It is also possible to adjust so that the emission peak wavelength is separated by 5 nm or more from any of the selective reflection center wavelengths for light with an incident angle of 5°. For this reason, as in the case of light with an incident angle of 60°, even for light with an incident angle of 5°, the balance of light intensity in the visible light region after being reflected by the reflective film is adjusted, and the reflected light is The color can be made neutral, and the transparency of the appearance color can be sufficiently enhanced. Thus, by using the reflective film of the present invention, the relationship between the emission peak of the fluorescent dye and the selective central wavelength of the selective reflection layer can be obtained at an angle of at least 60° or thereabouts, and further at the incident angle of 5°. By adjusting the angle, it is possible to effectively improve the transparency of the appearance color even at an angle of 5° or thereabouts, and as a result, it is possible to effectively improve the transparency of the appearance color of the reflective film.

FIG. 1 shows an example of the HUD system of the present invention.
A HUD system 20 of the present invention shown in FIG. 1 includes a windshield glass 24 and a projector 22 .

In the HUD system 20 illustrated in FIG. 1, the projector 22 emits p-polarized projection light, and the reflective film 10 in the windshield glass 24 reflects the p-polarized light to display an image.

When the windshield glass 24A including the linearly polarized light reflecting film 10A shown in FIG. 2 is provided as the windshield glass 24, in the linearly polarized light reflecting film 10A, the retardation layer 16 first enters from the second glass plate 28 side. It converts p-polarized projected light into circularly polarized light. Next, the selective reflection layer 11 (cholesteric liquid crystal layer 12 ) selectively reflects this circularly polarized light and reenters the retardation layer 16 . Furthermore, the retardation layer 16 converts circularly polarized light into p-polarized light. The linearly polarized light reflecting film 10A thereby reflects the incident p-polarized projection light as the p-polarized light.
Therefore, according to the sense of the circularly polarized light selectively reflected by the selective reflection layer 11 (cholesteric liquid crystal layer 12), the retardation layer 16 converts the incident p-polarized light into circularly polarized light in the rotating direction that the selective reflection layer 11 reflects. is set to convert to That is, when the selective reflection layer 11 selectively reflects right-handed circularly polarized light, the retardation layer 16 is set to convert incident p-polarized light into right-handed circularly polarized light. Conversely, when the selective reflection layer 11 selectively reflects left-handed circularly polarized light, the retardation layer 16 is set to convert incident p-polarized light into left-handed circularly polarized light.

When the windshield glass 24B including the linearly polarized reflective film 10B shown in FIG. reflected as p-polarized light.

In the HUD system 20, the projector 22 preferably irradiates the second glass plate 28 in the windshield glass 24 with p-polarized projection light. By making the projection light that the projector 22 irradiates onto the windshield glass 24 p-polarized light, the reflection of the projection light from the first glass plate 30 and the second glass plate 28 of the windshield glass 24 is greatly reduced. Inconveniences such as the observation of double images can be suppressed.
Preferably, the projector 22 irradiates the windshield glass 24 with p-polarized projection light at Brewster's angle. This eliminates the reflection of the projection light on the first glass plate 30 and the second glass plate 28, making it possible to display a clearer image.

<Windshield glass>
In FIG. 1, the windshield glass 24 is windshield glass having a second glass plate 28, a reflective film 10 including a selective reflection layer, and a first glass plate 30 in this order.

Windshield glass means window glass and windshield glass for vehicles such as cars and trains, airplanes, ships, motorcycles, and vehicles in general such as playground equipment. The windshield glass is preferably used as a windshield, a windshield, etc. in front of the traveling direction of the vehicle.

The windshield glass 24A shown in FIG. 2 has a first glass plate 30, an intermediate film 36, a linearly polarized reflecting film 10A, a heat seal layer 38, and a second glass plate 28 in this order.
In FIG. 2, the linearly polarized light reflecting film 10A is arranged such that the polarization conversion layer 14 is on the first glass plate 30 side and the retardation layer 16 (transparent substrate 18) is on the second glass plate 28 side. ing.
The windshield glass 24B shown in FIG. 3 has a first glass plate 30, an intermediate film 36, a linearly polarized reflecting film 10B, an intermediate film 36, and a second glass plate 28 in this order.

When the windshield glass is used in a vehicle, curved glass is often used as the second glass plate 28 and the first glass plate 30 . In that case, if the second glass plate 28 is on the inside of the vehicle and the first glass plate 30 is on the outside of the vehicle, the second glass plate 28 is arranged with the convex side facing the first glass plate 30, and the first The second glass plate 30 is arranged with the concave side facing the second glass plate 28 .

When the second glass plate 28 and the first glass plate 30 are curved glasses, the example shown in FIG. are placed. Also, the retardation layer 16 is arranged between the selective reflection layer 11 and the second glass plate 28 .

The visible light transmittance of the windshield glass is preferably 70% or more, more preferably over 70%, even more preferably 75% or more, and particularly preferably 80% or more, from the viewpoint of legal regulations.
The above-mentioned visible light transmittance is preferably satisfied at any position of the windshield glass, and it is particularly preferable that the above-mentioned visible light transmittance is satisfied at the position where the reflective film exists. As will be described later, the reflective film can increase the visible light transmittance, and the above-mentioned visible light transmittance is satisfied regardless of the glass generally used for windshield glass. can do.

There are no restrictions on the shape of the windshield glass, and it is determined as appropriate according to the object on which the windshield glass is arranged. The windshield glass may be, for example, planar or three-dimensional with a curved surface such as a concave surface or a convex surface. In the windshield glass molded for the vehicle to which it is applied, it is possible to specify the faces facing upwards during normal use, the viewing side such as the viewer side, the driver side, and the inside of the vehicle.

In the windshield glass, the reflective film may be provided at the projected image display portion (projected image reflection portion) of the windshield glass.
Further, in the windshield glass, the reflective film may be provided between the glass panes of the windshield glass in the structure of laminated glass, or may be provided on the outer surface of the glass plate of the windshield glass. .

When the reflective film including the selective reflection layer used in the present invention is provided on the outer surface of the glass plate of the windshield glass, the reflective film may be provided inside the vehicle (on the incident side of the projected image) or outside. However, it is preferably provided inside.
It should be noted that the reflective film containing the selective reflective layer used in the present invention has lower scratch resistance than the glass plate. Therefore, in the HUD system of the present invention, the windshield glass has a laminated glass structure, and in order to protect the reflective film, the reflective film consists of two sheets of glass (a first glass plate and a second glass plate) that constitute the laminated glass. It is a configuration provided between plates).

As described above, the reflective film is a member for displaying a projected image by reflecting the projected image. Therefore, the reflective film may be provided at a position where a projection image projected from a projector or the like can be visually displayed.
That is, the reflective film including the selective reflective layer used in the present invention functions as a combiner of the HUD system. In the HUD system, the combiner can visually display the image projected from the projector, and when the combiner is observed from the incident surface side of the projected image, the incident surface of the projected light such as scenery is opposite to the incident surface. It means an optical member that can simultaneously observe information on the surface side. That is, the combiner has a function as an optical path combiner that superimposes external light and projected image light for display.

The reflective film may be provided on the entire surface of the windshield glass, or may be provided on a part of the windshield glass in the surface direction, but it is preferably provided on a part of the windshield glass.
When the reflective film is provided on part of the windshield glass, the reflective film may be provided at any position on the windshield glass. is preferably provided as shown. For example, the position of the reflective film on the windshield may be determined based on the relationship between the position of the driver's seat in the vehicle in which the HUD system is installed and the position of the projector.
The reflective film may be planar without curved surfaces, but may have curved surfaces. Moreover, the reflective film may have a concave or convex shape as a whole, and may display the projected image by enlarging or reducing it.

[1] Reflective film In the reflective film 10 of the present invention, the selective reflection center wavelength for light with an incident angle of 60° is the selective reflection layer (I) having the above specification (a) and the selection having the above specification (b). Each selective reflection center for light having an incident angle of 60° in the selective reflection layers (I) to (III) having at least the reflection layer (II) and the selective reflection layer (III) defined in (c) above. There is no particular limitation as long as at least one fluorescent dye having an emission peak separated by 5 nm or more in the visible light region for any wavelength is included.

[Selective reflection layer]
The windshield glass used in the HUD system of the present invention has the selective reflection layers (I) to (III).
That is, the selective reflection layers (I) to (III) include three wavelengths λ _B , λ _G and λ _R as selective reflection center wavelengths for light with an incident angle of 60°.

In the present invention, the selective reflection central wavelengths of the selective reflection layers (I) to (III) and the half widths of the reflection peaks having the selective reflection central wavelengths are obtained as follows.

Using a spectrophotometer (manufactured by JASCO Corporation, V-670), when the reflection spectrum is measured at a desired angle of incidence (for example, 60°) with respect to the normal direction of the selective reflection layer, the reflectance in the selective reflection band is A maximum peak of is seen. Of the two wavelengths that have an intermediate (average) reflectance between the maximum reflectance of this peak and the minimum reflectance at the foot of the maximum peak, the value of the wavelength on the short wavelength side is λ l (nm), and the value of the wavelength on the long wavelength side is λ _l (nm). Assuming that the wavelength is λ _h (nm), the selective reflection central wavelength λ and its half width Δλ can be expressed by the following equations.
λ=(λ _l +λ _h )/2
Δλ=( _λh − _λl )
When the selective reflection layer is made of a cholesteric liquid crystal, the selective reflection central wavelength obtained as described above is the centroid position of the reflection peak of the circularly polarized reflection spectrum measured at a desired incident angle with respect to the normal direction of the selective reflection layer. It approximately matches a certain wavelength.
It should be noted that the reflection spectrum of the selective reflection layer is measured in the state of the windshield glass including the selective reflection layer.

The natural light reflectance _RB at λ _B of the selective reflection layer (I), the natural light reflectance _RG at λ _G of the selective reflection layer (II), and the natural light reflectance _RR at λ _R of the selective reflection layer (III) are , the relationship _RB > _RG ≥ _RR is preferably satisfied from the viewpoint of making the reflected color closer to white at an incident angle of light of 60° and further improving the transparency of the appearance color.
In addition, the natural light reflectances _RB and _RG of the selective reflection layers (I) and (II) are determined from the viewpoint of making the reflected color closer to white at an incident angle of 5° and further improving the transparency of the appearance color. , R _B /R _G ≧1.10.
The upper limit of _RB / _RG is not particularly limited, but 1.30 or less is practical. Also, R _G /R _R is not particularly limited, but is practically 0.90 to 1.10, preferably 1.00 to 1.10.
In the present invention, the natural light reflectance at the selective reflection central wavelength of the selective reflection layer is determined by the method described in Examples below.

As mentioned above, in-vehicle head-up display systems are required to have a transparent exterior color even when viewed from various angles in terms of transmittance and design that exceed legal requirements. Conventionally, it has been considered to lower the reflectance in order to maintain the legal transmittance of 70% or more and make the appearance color closer to transparent (white). However, if the reflectance is lowered too much, the brightness of the displayed image (projected image) is lowered, resulting in poor visibility.

In the present invention, the selective reflection layers (I) to (III) are used from the viewpoint of efficiently reflecting the imager light and increasing the brightness of the image (clearness of the displayed image) while maintaining a high transmittance. All of the half widths of the selective reflection center wavelengths λ _B , λ _G and λ _R for light with an incident angle of 60° are 100 nm or less, and the above natural light reflectances _RB , _RG and _RR are Both are preferably 25% or more.
In the windshield glass in which the reflective film having the selective reflection layers (I) to (III) with the above-mentioned selective reflection center wavelength having a half value width of 100 nm or less and a natural light reflectance of 25% or more is sandwiched between green glasses, natural light Transmittance can be 70% or more (80% or more when clear glass is sandwiched).

From the viewpoint of being able to increase the transmittance while _improving the reflected color, the natural light reflectance _RB at _λB , the natural light reflectance _RG at _λG , and the natural light reflectance _RR at λR are all , preferably 25 to 60%, more preferably 30 to 50%.

From the viewpoint of being able to increase the transmittance while improving the reflected color, the half width of the selective reflection center wavelength λ _B for light with an incident angle of 60° is preferably 10 to 100 nm, more preferably 15 to 40 nm. .
Similarly, from the viewpoint of being able to increase the transmittance while improving the reflected color, the half width of the selective reflection center wavelength λ _G for light with an incident angle of 60° is preferably 10 to 100 nm, and 15 to 55 nm. is more preferred.
Similarly, from the viewpoint of being able to increase the transmittance while improving the reflected color, the half width of the selective reflection center wavelength λ _R for light with an incident angle of 60° is preferably 10 to 100 nm, and 15 to 55 nm. is more preferred.

The reflective film of the present invention is a layer having a selective reflection center wavelength λ _UV for light with an incident angle of 60° in a wavelength range of 300 nm or more and less than 400 nm (also simply referred to as a “UV layer”. For example, the cholesteric liquid crystal layer UV ) is preferred. The selective reflection central wavelength λ _UV of the UV layer for light with an incident angle of 60° is preferably 330 to 395 nm, more preferably 350 to 390 nm.
Further, the natural light reflectance R _UV at the selective reflection center wavelength λ _UV is preferably 25 to 60%, more preferably 30 to 50%. The half width of the selective reflection central wavelength λ _UV for light with an incident angle of 60° is preferably 10 to 100 nm, more preferably 15 to 40 nm.

The natural light reflectance and half-value width at the selective reflection center wavelength for light with an incident angle of 5° in the selective reflection layers (I) to (III) and the UV layer are the selective reflection center for the light with an incident angle of 60°. The value is approximately the same as the natural light reflectance and the half width at the wavelength.

In the reflective film of the present invention, each of the selective reflection center wavelengths λ _B , λ _G , and λ _R for light with an incident angle of 60° in the selective reflection layers (I) to (III) is separated by 5 nm or more. A fluorescent dye having an emission peak in the visible light region (hereinafter also simply referred to as a "fluorescent dye") may be contained in any layer constituting the reflective film.
For example, a selective reflection layer such as the selective reflection layers (I) to (III) may contain a fluorescent dye. FL”) may be provided. Further, when two or more types of fluorescent dyes are contained, a form in which the selective reflection layer contains the fluorescent pigments and a form in which the fluorescent pigment layer FL is provided may be used in combination. Among the laminated selective reflection layers, the selective reflection layer positioned closest to the surface contains a fluorescent dye, and/or the selective reflection layer is positioned on one surface of the laminated selective reflection layers. Preferably, a fluorescent pigment layer FL is provided in the laminated selective reflection layer, and the fluorescent pigment is contained in the selective reflection layer located on the outermost side of the vehicle among the laminated selective reflection layers, and / or the laminated selective reflection layer It is more preferable to provide the fluorescent dye layer FL on the surface located on the vehicle outer side among the surfaces.
As the fluorescent dye, the description of the fluorescent dye described in the linear light reflecting film 10A described later can be applied, and it is preferable to contain the first fluorescent dye described later. When two or more fluorescent dyes are contained, it is more preferable to contain the second fluorescent dye described later in addition to the first fluorescent dye described later.

Reflective films containing the selective reflection layers (I) to (III) include, for example, a linearly polarized light reflecting film containing a cholesteric liquid crystal layer having a function of reflecting circularly polarized light, an optically anisotropic layer and an optically isotropic layer. A preferred example is a linearly polarized light reflecting film comprising a selective reflection layer (hereinafter also referred to as a “dielectric multilayer film”) having a function of reflecting linearly polarized light.
Hereinafter, the linearly polarized light reflecting film and the linearly polarized light reflecting film are based on the linearly polarized light reflecting film 10A in the windshield glass 24A shown in FIG. 2 and the linearly polarized light reflecting film 10B in the windshield glass 24B shown in FIG. explain. Further, the cholesteric liquid crystal layer will be described in the description of the linearly polarized light reflecting film, and the dielectric multilayer film will be described in the description of the linearly polarized light reflecting film.

[1-1] Linearly polarized reflective film 10A
FIG. 2 is a schematic diagram showing an example of the windshield glass 24 used in the present invention. The linearly polarized light reflective film 10A included in the windshield glass 24 includes the polarization conversion layer 14, the selective reflection layer 11, the position It has a retardation layer 16 and a transparent substrate 18 in this order.

The selective reflection layer 11 includes three cholesteric liquid crystal layers (12R, 12G, 12B). The three cholesteric liquid crystal layers have different central wavelengths of selective reflection for light with an incident angle of 60°, and each cholesteric liquid crystal layer _12B (selective reflection layer (I )), a cholesteric liquid crystal layer 12G (selective reflection layer (II)) having λ _G for light with an incident angle of 60°, and a cholesteric liquid crystal layer _12R (selective reflection layer (III)). In the illustrated example, it has a cholesteric liquid crystal layer 12R, a cholesteric liquid crystal layer 12G, and a cholesteric liquid crystal layer 12B in this order. Also, in the illustrated example, each cholesteric liquid crystal layer is in direct contact with any other cholesteric liquid crystal layer.

Although not shown in FIG. 2, in addition to the three cholesteric liquid crystal layers (12R, 12G, 12B), the selective reflection center wavelength for light with an incident angle of 60° is 300 nm or more and less than 400 nm. Inclusion of a cholesteric liquid crystal layer having λ _UV (hereinafter referred to as cholesteric liquid crystal layer UV) is also preferable from the viewpoint of suppressing reflected color.
By providing the cholesteric liquid crystal layer UV, when the windshield glass is configured to include a circularly polarized light reflecting layer and a retardation layer, which will be described later, as described above, it is confirmed when the windshield glass is observed under external light. It is possible to suppress the tint (especially the yellow tint in the reflected tint for light with an incident angle of 5°).

One preferred form of the present invention includes a form in which any one of the three cholesteric liquid crystal layers (12R, 12G, 12B) contains a fluorescent dye. More preferably, the layer 12R contains a fluorescent dye (hereinafter referred to as the first fluorescent dye). The first fluorescent dye emits light when excited by excitation light such as sunlight or UV light. As this excitation light, light that is absorbed by the first fluorescent dye, in other words, light with a wavelength shorter than the wavelength of the absorption edge on the long wavelength side of the absorption spectrum of the first fluorescent dye is used.
The first fluorescent dye contained in the cholesteric liquid crystal layer 12R is a quantum dot. The quantum dots are excited by excitation light and emit light. The first fluorescent dye is typically a quantum dot, but is not limited thereto, and may be a quantum rod, for example, compounds described in JP-A-2016-061833. Alternatively, the first fluorescent dye may be a compound contained in a europium compound, a stilbene compound, or a quinoline compound. Specific examples of such compounds include, for example, JP-A-2019-143025 (paragraph [0010] to [0012]).
In addition, by adjusting the particle size of quantum dots, the color of the emitted fluorescence can be freely changed, the emission wavelength can be easily controlled, and it is robust and durable against photobleaching. Therefore, the first fluorescent dye is preferably a quantum dot.
In addition, in this specification, the said quantum dot means the quantum dot which has an emission peak wavelength in the range of 450 nm or more and less than 550 nm.
The emission peak wavelength of the first fluorescent dye (quantum dot) is present in the visible light region, and the selective reflection center wavelengths λ _R and λ _G of light with an incident angle of 60° on the cholesteric liquid crystal layers 12R, 12B, and 12G. , λ _B is not particularly limited as long as the distance is 5 nm or more. For example, the distance is preferably 10 nm or more, and more preferably 30 nm or more. In addition, as described above, the emission peak wavelength of the first fluorescent dye (quantum dot) is 5 nm or more with respect to any of the selective reflection central wavelengths for light with an incident angle of 5° on the cholesteric liquid crystal layers 12R, 12B, and 12G. It is preferably separated, more preferably 10 nm or more, and more preferably 30 nm or more. These are the same for the cholesteric liquid crystal layer UV described above.
In this specification, the emission peak wavelength is the wavelength at which the intensity of the emission spectrum becomes maximum (emission peak, emission maximum).
A quantum dot is a particle of a predetermined size (several nanometers to several tens of nanometers) that is composed of crystals of a semiconductor material and has a quantum confinement effect, and is excited by incident excitation light to emit fluorescence.
The average particle size of the quantum dots is about several nanometers to several tens of nanometers as described above, and is set to an average particle size corresponding to the target emission color. For example, when obtaining blue light, it is preferable to set the average particle size of the quantum dots within the range of 1.0 to 3.0 nm.
As a method for measuring the average particle size of the quantum dots, the particle sizes (diameters) of arbitrary 10 quantum dots are measured by observation with a transmission electron microscope (TEM), and the values are arithmetically averaged. In addition, when the quantum dot is not perfectly circular, the major axis is taken as the particle diameter.

Although the aspect ratio (major axis/minor axis) of the quantum dots is not particularly limited, it is preferably in the range of 1.0 to 2.0, more preferably in the range of 1.0 to 1.7.
The aspect ratio of the quantum dots is obtained by measuring the length and breadth of at least 10 or more quantum dots by observation with a transmission electron microscope (TEM), determining the aspect ratios, and arithmetically averaging them.
Note that the major axis of the quantum dot is the longest line segment that intersects the quantum dot in a two-dimensional image of the quantum dot obtained by microscopic (for example, transmission electron microscope) observation. The minor axis refers to the longest line segment perpendicular to the major axis and crossing the quantum dots.

Materials constituting the quantum dots are not particularly limited as long as the quantum dots emit light of a desired wavelength, and are usually composed of semiconductors such as II-VI semiconductors, III-V semiconductors, IV-VI semiconductors, Alternatively, a combination of these may be mentioned. More specifically, CdS, CdSe, CdTe, ZnS, ZnSe, ZnSeS, ZnTe, ZnO, GaAs, GaP, GaAs, GaSb, HgS, HgSe, HgTe, InAs, InP, InSb, AlAs, AlP, AlSb, CuS, _Cu2S , _Cu2Se , CuInS, _CuInS2 , _CuInSe2 , _Cu2 (ZnSn) _S4 , _Cu2 (InGa) _S4 , _TiO2 alloys thereof, and mixtures thereof.
The quantum dots are preferably selected from CdS, CdSe, ZnS, ZnSe, InP, CuS and CuInS.
The quantum dots may be monocomponent quantum dots or core/shell quantum dots with a core of a first semiconductor and a shell of a second semiconductor. A core/multiple shell type quantum dot may also be used, and a quantum dot having a core/shell structure with a graded composition of the shell may also be used.

In addition to the first fluorescent dye, the cholesteric liquid crystal layer 12R of the present invention contains a fluorescent dye different from the first fluorescent dye (hereinafter referred to as a second fluorescent dye). It is preferable from the viewpoint of further increasing the transparency of.

The second fluorochrome is excited by excitation light such as sunlight or UV light to emit light. As the excitation light, light absorbed by the second fluorescent dye, in other words, light having a wavelength shorter than the wavelength of the absorption edge on the long wavelength side of the absorption spectrum of the second fluorescent dye is used.
The second fluorochrome is a quantum dot. The quantum dots are excited by excitation light and emit light. In this specification, the quantum dot as the second fluorescent dye means a quantum dot having an emission peak wavelength outside the range of 450 nm or more and less than 550 nm (for example, within the range of 550 nm or more and 650 nm or less).
The emission peak wavelength of the second fluorescent dye (quantum dot) is 5 nm or more apart from each of the selective reflection center wavelengths λ _R , λ _G , and λ _B of the cholesteric liquid crystal layers 12R, 12B, and 12G. Although it is not particularly limited as long as it is, for example, it is preferably 10 nm or more, more preferably 30 nm or more. Further, as described above, the emission peak wavelength of the second fluorescent dye (quantum dot) is 5 nm or more for any of the central wavelengths of selective reflection of light with an incident angle of 5° on the cholesteric liquid crystal layers 12R, 12B, and 12G. It is preferably separated, more preferably 10 nm or more, and even more preferably 25 nm or more. These are the same for the cholesteric liquid crystal layer UV described above.

As the material constituting the quantum dots, which are the second fluorescent dye, the same materials as those constituting the quantum dots, which are the first fluorescent dye, are appropriately selected.
The average particle diameter of the quantum dots, which are the second fluorescent dye, is about several nanometers to several tens of nanometers as described above, and is set to an average particle diameter corresponding to the target emission color. For example, when it is desired to obtain green light, it is preferable to set the average particle size of the quantum dots within the range of 1.5 to 10 nm.
As the aspect ratio of the quantum dots, which are the second fluorescent dye, the same aspect ratio as that of the quantum dots, which are the first fluorescent dye, is adopted.

Further, as another form of the reflective film of the present invention, the selective reflection layer may not contain a fluorescent dye, and a layer that does not function as a selective reflection layer may be provided as the layer containing the fluorescent dye. In addition, a mode in which a fluorescent dye is contained in the selective reflection layer and a mode in which a layer containing the fluorescent dye and not functioning as a selective reflection layer (hereinafter referred to as a fluorescent dye layer FL) is provided may be used in combination. good.
For example, in FIG. 2, a fluorescent dye layer FL may be provided as a layer other than the cholesteric liquid crystal layers 12B, 12G and 12R (not shown), and on the cholesteric liquid crystal layer 12R (the cholesteric liquid crystal layer 12 and the polarization conversion layer 14). or between the cholesteric liquid crystal layer 12R and the cholesteric liquid crystal layer 12G), or between the cholesteric liquid crystal layer 12B and the cholesteric liquid crystal layer 12G. It is more preferable to provide between the cholesteric liquid crystal layer 12 and the polarization conversion layer 14, which are located outside the vehicle.

When the first fluorescent dye having an emission wavelength peak of 450 nm or more and less than 550 nm is included, the reflective film of the present invention is supplemented with a color corresponding to a wavelength range of 450 nm or more and less than 550 nm, preferably λ _B and λ The hue of the wavelength range between _G is compensated. Further, when the first fluorescent dye having an emission wavelength peak of 450 nm or more and less than 550 nm and the second fluorescent dye having a light wavelength peak of 550 nm or more and 650 nm or less are included, the reflective film of the present invention has a wavelength of 450 nm. In addition to supplementing the color tone corresponding to the range of 550 nm or more and less than 550 nm, the second fluorescent dye compensates the color tone corresponding to the wavelength range of 550 nm or more and 650 nm or less, preferably between λ _G and λ _R The color of the wavelength range of is compensated for. Therefore, it is possible to adjust the balance of the light intensity in the visible light region of the light reflected from the windshield glass so that the reflected color becomes more neutral, and the transparency of the appearance color can be further improved. can.

The fluorochrome layer FL contains the above-described first fluorochrome. The fluorescent dye layer FL is a light-emitting layer that emits light when excited by excitation light such as sunlight or UV light, and is a layer that does not function as a selective reflection layer. The fluorescent dye layer FL contains the quantum dots described above, and the quantum dots are excited by excitation light to emit light.

Although the content of the quantum dots in the fluorescent dye layer FL is not particularly limited, it is preferably 0.01 to 3% by mass, and 0.05 to 1% by mass is more preferred.

The fluorescent dye layer FL may contain components other than the quantum dots, and preferably contains a polymer as a binder.
The type of polymer is not particularly limited, and known polymers can be used. Examples include polyolefin resins such as polyethylene and polypropylene, polyester resins such as polyethylene terephthalate and polyethylene naphthalate, and polyacrylic resins such as polymethyl methacrylate. resins, polyurethane resins, polycarbonate resins, polyether resins, epoxy resins, silicone resins, and the like.

Although the thickness of the fluorescent dye layer FL is not particularly limited, it is preferably from 5 to 300 μm, more preferably from 30 to 200 μm, from the standpoint of better light emission characteristics and color reproducibility.
The above thickness is an average thickness, and is a value obtained by measuring the thickness at arbitrary 10 points of the fluorescent dye layer FL and arithmetically averaging them.

The method for producing the fluorescent dye layer FL is not particularly limited, and a known method can be used. For example, a fluorescent dye layer-forming composition containing quantum dots and a polymer is coated on a predetermined substrate, If necessary, a method of applying a drying treatment, or a coating film is formed by applying a curable composition containing quantum dots and a polymerizable monomer on a predetermined substrate, and the coating film is cured (light irradiation treatment and/or heat treatment). In these methods, instead of the substrate, the fluorescent dye layer FL may be directly provided on the selective reflection layer.
Known coating methods include curtain coating, dip coating, spin coating, print coating, spray coating, slot coating, roll coating, slide coating, blade coating, gravure coating, and wire bar coating. and a coating method.

The polymerizable monomer used in the curable composition is preferably a radically polymerizable compound from the viewpoint of reactivity. Preferred are (meth)acrylate compounds such as functional or polyfunctional (meth)acrylate monomers, polymers thereof, prepolymers, and the like.
Moreover, the curable composition may further contain a polymerization initiator (eg, a radical initiator). Regarding the polymerization initiator, for example, paragraph [0037] of JP-A-2013-043382 can be referred to. The polymerization initiator is preferably 0.1 mol % or more, more preferably 0.5 to 2 mol %, of the total mass of the polymerizable monomers contained in the curable composition.
The curable composition may further contain other components (for example, solvent).

By providing the reflective film of the present invention with the fluorescent pigment layer FL, the same effect as when the cholesteric liquid crystal layer (preferably the cholesteric liquid crystal layer 12R) contains the fluorescent pigment can be obtained. That is, it is possible to adjust the balance of the light intensity in the visible light region of the light reflected from the windshield glass, and to make the reflected color neutral.

As is well known, the cholesteric liquid crystal layer is a layer in which a liquid crystal compound is fixed in the orientation state of the helical structure of the cholesteric liquid crystal phase, and reflects light of the selective reflection center wavelength according to the pitch of the helical structure, and reflects light of other wavelengths. permeates a wide range of light. In addition, the cholesteric liquid crystal layer exhibits selective reflectivity for either left or right circularly polarized light at a specific wavelength.

In the selective reflection layer having a cholesteric liquid crystal layer, the reflected wavelength and reflectance can be adjusted by the selective reflection center wavelength, thickness (helical pitch number), etc. of the cholesteric liquid crystal layer.

Here, as shown in FIG. 2, each cholesteric liquid crystal layer is preferably in direct contact with any other cholesteric liquid crystal layer. For example, in the example shown in FIG. 2, the cholesteric liquid crystal layer 12R having λ _R for light with an incident angle of 60° and the cholesteric liquid crystal layer 12G having λ _G for light with an incident angle of 60° are in contact with each other, Also, the cholesteric liquid crystal layer 12G having λ _G for light with an incident angle of 60° and the cholesteric liquid crystal layer 12B having λ _B for light with an incident angle of 60° are in contact with each other.

When the cholesteric liquid crystal layers are spaced apart from each other, the film thickness between the layers becomes thicker, making it difficult to obtain the effect of interference of light reflected by each cholesteric liquid crystal layer. On the other hand, by adopting a configuration in which the cholesteric liquid crystal layers are in contact with each other, the wavelength band width can be narrowed by the effect of interference of light reflected by each cholesteric liquid crystal layer. In particular, when the film thickness of each cholesteric liquid crystal layer is thinner than the wavelength of light (380 nm to 780 nm of visible light), the effect of interference becomes more pronounced.

In addition, in the present invention, each cholesteric liquid crystal layer is not limited to a configuration in which they are in direct contact, and may be configured to be laminated via an adhesive layer or the like.

Here, each cholesteric liquid crystal layer has at least one selective reflection central wavelength among the three wavelengths λ _B , λ _G and λ _R as the selective reflection central wavelength for light with an incident angle of 60°. However, at least one of the cholesteric liquid crystal layers may have two or more selective reflection central wavelengths. A cholesteric liquid crystal layer having two or more selective reflection center wavelengths is achieved by a helical structure in which the helical pitch varies in the thickness direction.

In the illustrated example, the selective reflection layer 11 has three layers of cholesteric liquid crystal layers with different selective reflection central wavelengths, but the selective reflection layer 11 is not limited to this. It may have a liquid crystal layer.

The total thickness of the selective reflection layer 11 is preferably 0.5 to 30 μm, more preferably 1 to 15 μm, from the viewpoint of exhibiting high transmittance while exhibiting sufficient natural light reflectance by the selective reflection layer 11 .

Here, the reflective film preferably reflects linearly polarized light. When the reflective film is incorporated into the windshield glass and used as a combiner for a HUD system, the projected image light is preferably p-polarized, that is, linearly polarized, in order to suppress reflection on the windshield glass surface.
In the linearly polarized light reflecting film as shown in FIG. 2, the selective reflection layer made of a cholesteric liquid crystal layer reflects circularly polarized light.
Therefore, the linearly polarized light reflective film preferably has a layer for converting linearly polarized light incident on the reflective film into circularly polarized light. The layer that converts the polarization state of light includes a polarization conversion layer and a retardation layer.

The polarization conversion layer exhibits optical rotation and birefringence with respect to visible light, and converts the polarization state of incident light. In the present invention, the polarization conversion layer is composed of a layer in which a birefringent material such as a liquid crystal compound is oriented with a twist amount of 360° or less.
The phase difference layer changes the state of incident polarized light by adding a phase difference (optical path difference) to two orthogonal polarized light components. In the present invention, the retardation layer is a layer in which birefringent materials such as liquid crystal compounds are aligned in the same direction, and does not have optical rotation.

By configuring the reflective film to have a polarization conversion layer or a retardation layer on the light incident side of the selective reflective layer, the linearly polarized light incident on the reflective film is converted into circularly polarized light, and the selective reflective layer becomes circular. The polarized light can be reflected, and the reflected circularly polarized light can be converted into linearly polarized light by the polarization conversion layer or the retardation layer and emitted.

Here, in the example of the windshield glass shown in FIG. 2, the reflective film 10A has the polarization conversion layer 14 on one surface side of the selective reflection layer 11, the retardation layer 16 on the other surface side, The polarization conversion layer 14 is arranged on the side of the first glass plate 30, which is the outside of the vehicle, and the retardation layer 16 is arranged on the side of the second glass plate 28, which is the inside of the vehicle.

In this case, the retardation layer 16 has a function of converting projected p-polarized light (linearly polarized light) into circularly polarized light reflected by the cholesteric liquid crystal layer of the selective reflection layer 11 .
On the other hand, the polarization conversion layer 14 has a function of optically compensating for light incident from outside the windshield glass. For example, the s-polarized light incident from the outside of the windshield glass changes its polarization state when passing through the retardation layer 16, and the p-polarized component is mixed. Since polarized sunglasses cut s-polarized light, this p-polarized component is transmitted through polarized sunglasses. As a result, the function of the polarized sunglasses to cut the glare of the reflected light, which is mainly composed of s-polarized light, is impaired, which poses a problem that hinders driving. On the other hand, by adopting a structure having the polarization conversion layer 14 and performing optical compensation with the polarization conversion layer 14, suitability for polarized sunglasses can be improved.

In the example shown in FIG. 2, in the reflective film 10A, the polarization conversion layer 14 is on the side of the first glass plate 30 on the outside of the vehicle, and the retardation layer 16 is on the side of the second glass plate 28 on the inside of the vehicle. However, the configuration is not limited to this. The reflective film 10A may be arranged such that the polarization conversion layer 14 is on the side of the second glass plate 28, which is the inside of the vehicle, and the retardation layer 16 is on the side of the first glass plate 30, which is the outside of the vehicle.

In this case, the polarization conversion layer 14 has the function of converting projected p-polarized light (linearly polarized light) into circularly polarized light reflected by the cholesteric liquid crystal layer of the selective reflection layer 11 .
On the other hand, the retardation layer 16 has a function of optically compensating for light incident from the outside of the windshield glass, and the optical compensation by the retardation layer 16 can improve suitability for polarized sunglasses.

Further, the reflective film may have a structure having polarization conversion layers on both sides of the selective reflection layer 11, or may have a structure having retardation layers on both sides.
In this case, the polarization conversion layer or retardation layer disposed on the vehicle interior has a function of converting the projected p-polarized light (linearly polarized light) into circularly polarized light reflected by the cholesteric liquid crystal layer of the selective reflection layer 11. do it.
On the other hand, the polarization conversion layer or the retardation layer disposed on the vehicle exterior side may be configured to have a function of optically compensating for light incident from the outside of the windshield glass.
The polarization conversion layer and the retardation layer will be detailed later.

The cholesteric liquid crystal layer, the polarization conversion layer, the retardation layer, and the transparent substrate, which are the constituent elements of the linearly polarized light reflective film, will be described in detail below.

In the present invention, the cholesteric liquid crystal layer means a layer in which the cholesteric liquid crystal phase is fixed.
The cholesteric liquid crystal layer may be any layer as long as the alignment of the liquid crystal compound in the cholesteric liquid crystal phase is maintained. A cholesteric liquid crystal layer is typically formed by aligning a polymerizable liquid crystal compound in a cholesteric liquid crystal phase, and then polymerizing and curing by ultraviolet irradiation, heating, or the like to form a layer having no fluidity, and at the same time, Any layer may be used as long as it is changed to a state in which the orientation is not changed by an external field or external force. In the cholesteric liquid crystal layer, it is sufficient that the optical properties of the cholesteric liquid crystal phase are maintained in the layer, and the liquid crystal compound in the layer may no longer exhibit liquid crystallinity. For example, the polymerizable liquid crystal compound may be polymerized by a curing reaction and no longer have liquid crystallinity.

It is known that a cholesteric liquid crystal phase selectively reflects either right-handed circularly polarized light or left-handed circularly polarized light and transmits the other sense circularly polarized light. .
Many films formed from a composition containing a polymerizable liquid crystal compound are conventionally known as films containing a layer in which a cholesteric liquid crystal phase exhibiting selective reflection of circularly polarized light is fixed. You can refer to the technology.

The central wavelength of selective reflection of the cholesteric liquid crystal layer (selective reflection central wavelength) λ depends on the pitch P (= helical period) of the helical structure (helical alignment structure) in the cholesteric liquid crystal phase, and the average refractive index n of the cholesteric liquid crystal layer and λ=n×P. As can be seen from this formula, the selective reflection center wavelength can be adjusted by adjusting the n value and/or the P value.
The pitch P of the helical structure (1 helical pitch) is, in other words, the length of the helical axis direction corresponding to one turn of the helical structure. is the length in the direction of the helical axis that rotates 360°. The helical axis direction of a normal cholesteric liquid crystal layer coincides with the thickness direction of the cholesteric liquid crystal layer.

In the head-up display system described above, by using the windshield glass so that the light is obliquely incident, the reflectance on the surface of the glass plate on the projection light incident side can be reduced.
At this time, the light obliquely enters the cholesteric liquid crystal layer forming the selective reflection layer 11 of the reflection film 10 as well. For example, light incident at an angle of 45° to 70° with respect to the normal line of the reflective film 10 in air with a refractive index of 1 passes through the cholesteric liquid crystal layer with a refractive index of about 1.61 at an angle of about 26° to 36°. To Penetrate. In this case, the reflected wavelength shifts to the short wavelength side.
In a cholesteric liquid crystal layer in which the central wavelength of selective reflection for light with an incident angle of 0° is a wavelength λ, a light ray passes at an angle of θ2 with respect to the normal direction of the cholesteric liquid crystal layer (spiral axis direction of the cholesteric liquid crystal layer). The wavelength λd is expressed by the following equation when the selective reflection central wavelength at the time is the wavelength λd.
λd=λ×cos θ2

Therefore, for example, a cholesteric liquid crystal layer having a selective reflection center wavelength λ in the range of 650 to 780 nm can reflect projection light in the range of 520 to 695 nm when θ2 is 26° to 36°.
Since such a wavelength range is a wavelength range with high luminosity, it has a high degree of contribution to the luminance of a projected image, and as a result, a projected image with high luminance can be realized.

　The helical pitch of the cholesteric liquid crystal phase depends on the type of chiral agent used together with the polymerizable liquid crystal compound and its concentration, so the desired pitch can be obtained by adjusting these. As for the method of measuring the sense and pitch of the helix, the method described in "Introduction to Liquid Crystal Chemistry Experiments", edited by the Japanese Liquid Crystal Society, published by Sigma Publishing, 2007, page 46, and "Liquid Crystal Handbook", Liquid Crystal Handbook Editing Committee, Maruzen, page 196 is used. be able to.

For each cholesteric liquid crystal layer, a cholesteric liquid crystal layer with either right or left helix sense is used. The sense of circularly polarized light reflected by the cholesteric liquid crystal layer (the direction of rotation of the circularly polarized light) matches the sense of the helix.
When a plurality of cholesteric liquid crystal layers with different selective reflection center wavelengths are provided, the helical sense of each cholesteric liquid crystal layer may be the same or different.
However, it is preferred that the multiple cholesteric liquid crystal layers all have the same sense of helix.

When the reflective film 10 has a plurality of cholesteric liquid crystal layers as the selective reflection layer 11, the cholesteric liquid crystal layers exhibiting selective reflection in the same or overlapping wavelength ranges should not include cholesteric liquid crystal layers with different helical senses. is preferred. This is to prevent the transmittance in a specific wavelength range from dropping below 50%, for example.

The half width Δλ (nm) of the selective reflection band indicating selective reflection depends on the birefringence Δn of the liquid crystal compound and the pitch P described above, and follows the relationship Δλ=Δn×P. Therefore, the width of the selective reflection band can be controlled by adjusting Δn. Adjustment of Δn can be performed by adjusting the type or mixing ratio of the polymerizable liquid crystal compound, or by controlling the temperature during orientation fixation.
In order to form one type of cholesteric liquid crystal layer having the same center wavelength of selective reflection, 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 with the same pitch P and the same helix sense, the circular polarization selectivity can be increased at a particular wavelength.

When laminating a plurality of cholesteric liquid crystal layers in the selective reflection layer 11, a separately prepared cholesteric liquid crystal layer may be laminated using an adhesive or the like, or the previous cholesteric liquid crystal layer formed by a method described later may be laminated. A liquid crystal composition containing a polymerizable liquid crystal compound or the like may be applied directly to the surface of the layer, and the alignment and fixing steps may be repeated, but the latter is preferred.
By forming the next cholesteric liquid crystal layer directly on the surface of the previously formed cholesteric liquid crystal layer, the orientation direction of the liquid crystal molecules on the air interface side of the previously formed cholesteric liquid crystal layer and the cholesteric liquid crystal layer formed thereon are changed. This is because the alignment directions of the liquid crystal molecules on the lower side are matched, and the polarizing property of the laminate of the cholesteric liquid crystal layers is improved. In addition, it is because interference unevenness that can be caused by thickness unevenness of the adhesive layer is not observed.

The thickness of the cholesteric liquid crystal layer is preferably 0.2-10 μm, more preferably 0.3-8 μm, and even more preferably 0.4-5 μm.

(Method for producing cholesteric liquid crystal layer)
Materials and methods for forming the cholesteric liquid crystal layer will be described below.
A liquid crystal composition containing a polymerizable liquid crystal compound and a chiral agent (optically active compound) may be used as a material for forming the cholesteric liquid crystal layer. If necessary, the above liquid crystal composition mixed with a surfactant, a polymerization initiator, etc. and dissolved in a solvent, etc. is applied to the support, the alignment layer, the underlying cholesteric liquid crystal layer, etc., and cholesteric alignment is performed. After aging, the liquid crystal composition can be fixed by curing to form a cholesteric liquid crystal layer.

(Polymerizable liquid crystal compound)
The polymerizable liquid crystal compound may be a rod-like liquid crystal compound or a discotic liquid crystal compound, but is preferably a rod-like liquid crystal compound.
An example of the rod-like polymerizable liquid crystal compound forming the cholesteric liquid crystal layer is a rod-like nematic liquid crystal compound. Rod-shaped nematic liquid crystal compounds include azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, and alkoxy-substituted phenylpyrimidines. , phenyldioxanes, tolanes, and alkenylcyclohexylbenzonitriles are preferably used. Not only low-molecular-weight liquid crystal compounds but also high-molecular liquid-crystal compounds can be used.

A polymerizable liquid crystal compound is obtained by introducing a polymerizable group into a liquid crystal compound. Examples of polymerizable groups include unsaturated polymerizable groups, epoxy groups, and aziridinyl groups, with unsaturated polymerizable groups being preferred, and ethylenically unsaturated polymerizable groups being particularly preferred. Polymerizable groups can be introduced into molecules of liquid crystal compounds by various methods. The number of polymerizable groups possessed by the polymerizable liquid crystal compound is preferably 1 to 6, more preferably 1 to 3, in one molecule.
Examples of polymerizable liquid crystal compounds are described in Makromol. Chem. , 190, 2255 (1989); Advanced Materials 5, 107 (1993); U.S. Pat. No. 4,683,327; U.S. Pat. No. 5,622,648; U.S. Pat. , WO95/24455, WO97/00600, WO98/23580, WO98/52905, JP 1-272551, JP 6-016616, JP 7-110469, JP 11-080081, and , and compounds described in JP-A-2001-328973. Two or more types of polymerizable liquid crystal compounds may be used in combination. When two or more kinds of polymerizable liquid crystal compounds are used together, the alignment temperature can be lowered.

Further, the amount of the polymerizable liquid crystal compound added in the liquid crystal composition is preferably 80 to 99.9% by mass, and 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.

In order to improve the visible light transmittance, the cholesteric liquid crystal layer may have a low Δn. A low Δn cholesteric liquid crystal layer can be formed using a low Δn polymerizable liquid crystal compound. The low Δn polymerizable liquid crystal compound will be specifically described below.

(Low Δn polymerizable liquid crystal compound)
A narrow-band selective reflection layer can be obtained by forming a cholesteric liquid crystal phase using a low Δn polymerizable liquid crystal compound and fixing it to a film. Examples of low Δn polymerizable liquid crystal compounds include compounds described in WO2015/115390, WO2015/147243, WO2016/035873, JP-A-2015-163596, and JP-A-2016-053149. The description of WO2016/047648 can also be referred to for the liquid crystal composition that provides a selective reflection layer with a small half-value width.

The liquid crystal compound is also preferably a polymerizable compound represented by the following formula (I) described in WO2016/047648.

In formula (I), A represents an optionally substituted phenylene group or an optionally substituted trans-1,4-cyclohexylene group, L is a single bond, —CH ₂ O-, -OCH ₂ -, -(CH ₂ ) ₂ OC(=O)-, -C(=O)O(CH ₂ ) ₂ -, -C(=O)O-, -OC(=O) -, -OC(=O)O-, -CH=CH-C(=O)O-, and -OC(=O)-CH=CH-, and m represents a linking group selected from the group consisting of represents an integer of 3 to 12, and Sp ¹ and Sp ² are each independently 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 one or more of -CH ₂ - are -O-, -S-, -NH-, -N(CH ₃ )-, -C(=O)-, -OC(=O)-, or - represents a linking group selected from the group consisting of groups substituted with C(=O)O-, wherein Q ¹ and Q ² are each independently a hydrogen atom or represented by formulas Q-1 to Q-5 below; represents a polymerizable group selected from the group consisting of groups consisting of However, either one of Q ¹ and Q ² represents a polymerizable group. In the following formula, "●" indicates a binding site.

The phenylene group in formula (I) is preferably a 1,4-phenylene group.
Regarding the phenylene group and the trans-1,4-cyclohexylene group, the substituent when "optionally having a substituent" is not particularly limited, and examples thereof include alkyl groups, cycloalkyl groups, alkoxy groups, alkyl ether groups, amido groups, amino groups, halogen atoms, and substituents selected from the group consisting of a combination of two or more of the above substituents. Examples of substituents include substituents represented by -C(=O)-X ³ -Sp ³ -Q ³ described later. The phenylene group and 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.

The alkyl group may be linear or branched. The number of carbon atoms in the alkyl group is preferably 1-30, more preferably 1-10, even more preferably 1-6. Examples of alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, and neopentyl. 1,1-dimethylpropyl, n-hexyl, isohexyl, linear or branched heptyl, octyl, nonyl, decyl, undecyl or dodecyl radicals. The above description regarding alkyl groups also applies to alkoxy groups containing alkyl groups. Further, 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 examples of the above-mentioned alkyl groups, and the like. Halogen atoms include fluorine, chlorine, bromine, and iodine atoms.

The number of carbon atoms in the cycloalkyl group is preferably 3 to 20, more preferably 5 or more, preferably 10 or less, more preferably 8 or less, and even more preferably 6 or less. Examples of cycloalkyl groups include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl and cyclooctyl groups.

Substituents which the phenylene group and the trans-1,4-cyclohexylene group may have are particularly an alkyl group, an alkoxy group, and the group consisting of -C(=O)-X ³ -Sp ³ -Q ³ Substituents selected from are preferred. Here, X ³ represents a single bond, -O-, -S-, or -N(Sp ⁴ -Q ⁴ )-, or represents a nitrogen atom forming a ring structure together with Q ³ and Sp ³ show. Sp ³ and Sp ⁴ are each independently 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, and one or more of - CH ₂ - is -O-, -S-, -NH-, -N(CH ₃ )-, -C(=O)-, -OC(=O)-, or -C(=O)O- A linking group selected from the group consisting of substituted groups is shown.

Each of Q ³ and Q ⁴ is independently a hydrogen atom, a cycloalkyl group, or a cycloalkyl group in which one or more —CH ₂ — is —O—, —S—, —NH—, —N(CH ₃ )-, -C(=O)-, -OC(=O)-, or a group substituted with -C(=O)O-, or a group represented by formulas Q-1 to Q-5 represents any polymerizable group selected from the group consisting of

one or more -CH ₂ - in the cycloalkyl group is -O-, -S-, -NH-, -N(CH ₃ )-, -C(=O)-, -OC(=O) Specific examples of groups substituted with - or -C(=O)O- include a tetrahydrofuranyl group, a pyrrolidinyl group, an imidazolidinyl group, a pyrazolidinyl group, a piperidyl group, a piperazinyl group, and a morphonyl group. . The substitution position is not particularly limited. Among these, a tetrahydrofuranyl group is preferred, and a 2-tetrahydrofuranyl group is particularly preferred.

In formula (I), L is a single bond, -CH ₂ O-, -OCH ₂ -, -(CH ₂ ) ₂ OC(=O)-, -C(=O)O(CH ₂ ) ₂ -,- C(=O)O-, -OC(=O)-, -OC(=O)O-, -CH=CH-C(=O)O-, and -OC(=O)-CH=CH represents a linking group selected from the group consisting of -. L is preferably -C(=O)O- or -OC(=O)-. m−1 Ls may be the same or different.

Sp ¹ and Sp ² are each independently 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, and one or more of - CH ₂ - is -O-, -S-, -NH-, -N(CH ₃ )-, -C(=O)-, -OC(=O)-, or -C(=O)O- A linking group selected from the group consisting of substituted groups is shown. Sp ¹ and Sp ² each independently has 1 carbon atom and a linking group selected from the group consisting of -O-, -OC(=O)-, and -C(=O)O- is attached to both ends. A group selected from the group consisting of straight-chain alkylene groups of from to 10, -OC(=O)-, -C(=O)O-, -O-, and straight-chain alkylene groups of 1 to 10 carbon atoms is preferably a linking group constituted by combining one or two or more of and is preferably a linear alkylene group having 1 to 10 carbon atoms and having —O— attached to both ends.

Q ¹ and Q ² each independently represent a hydrogen atom or a polymerizable group selected from the group consisting of the groups represented by the above formulas Q-1 to Q-5, provided that Q ¹ and Q ² Either one represents a polymerizable group.
As the polymerizable group, an acryloyl group (formula Q-1) or a methacryloyl group (formula Q-2) is preferred.

In formula (I), m represents an integer of 3-12. 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 formula (I) has at least one optionally substituted phenylene group as A and an optionally substituted trans-1,4-cyclohexylene group. It is preferable to include at least one. The polymerizable compound represented by 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 preferred, and 2 or 3 is even more preferred. Further, the polymerizable compound represented by the formula (I) preferably contains one or more phenylene groups which may have a substituent as A, more preferably contains 1 to 4 groups, 1 to It is more preferable to contain 3, and it is particularly preferable to contain 2 or 3.

In formula (I), when mc is the number obtained by dividing the number of trans-1,4-cyclohexylene groups represented by A by m, 0.1<mc<0.9 is preferable, and 0.3< mc<0.8 is more preferred, and 0.5<mc<0.7 is even more preferred. The polymerizable compound represented by the formula (I) having a liquid crystal composition satisfying 0.5<mc<0.7 and the polymerizable compound represented by the formula (I) satisfying 0.1<mc<0.3 It is also preferred to include

Specific examples of the polymerizable compound represented by formula (I) include, in addition to the compounds described in paragraphs 0051 to 0058 of WO2016/047648, JP-A-2013-112631, JP-A-2010-070543, Japanese Patent No. 4725516, WO2015/115390, WO2015/147243, WO2016/035873, JP-A-2015-163596, and compounds described in JP-A-2016-053149.

(Chiral Agent: Optically Active Compound)
A chiral agent has a function of inducing a helical structure of a cholesteric liquid crystal phase. The chiral compound may be selected according to the purpose, since the helical sense or helical pitch induced by the compound differs.
The chiral agent is not particularly limited, and commonly used compounds can be used. Examples of chiral agents include Liquid Crystal Device Handbook (Chapter 3, Section 4-3, Chiral Agents for TN and STN, p. Examples include compounds described in JP-A-2002-302487, JP-A-2002-080478, JP-A-2002-080851, JP-A-2010-181852, and JP-A-2014-034581.

A chiral agent generally contains an asymmetric carbon atom, but an axially chiral compound or planar asymmetric compound that does not contain an asymmetric carbon atom can also be used as a chiral agent. Examples of axially or planarly chiral 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, a repeating unit derived from the polymerizable liquid crystal compound and a repeating unit derived from the chiral agent are formed by the polymerization reaction of the polymerizable chiral agent and the polymerizable liquid crystal compound. A polymer having repeating units can be formed. In this aspect, the polymerizable group possessed by the polymerizable chiral agent is preferably the same type of group as the polymerizable group possessed by the polymerizable liquid crystal compound. Therefore, the polymerizable group of the chiral agent is also preferably an unsaturated polymerizable group, an epoxy group or an aziridinyl group, more preferably an unsaturated polymerizable group, and an ethylenically unsaturated polymerizable group. Especially preferred.
Also, the chiral agent may be a liquid crystal compound.

As the chiral agent, isosorbide derivatives, isomannide derivatives, binaphthyl derivatives, 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. In addition, the content of the chiral agent in the liquid crystal composition intends the concentration (% by mass) of the chiral agent with respect to the total solid content in the composition.

Further, as described above, the cholesteric liquid crystal layer of the selective reflection layer of the linearly polarized light reflection film may have two or more selective reflection central wavelengths. A cholesteric liquid crystal layer having two or more selective reflection central wavelengths is achieved by changing the pitch of the helical structure in the thickness direction. The cholesteric liquid crystal layer, in which the pitch of the helical structure changes in the thickness direction, is formed by using a chiral agent whose helical twisting power (HTP) changes when irradiated with light. It can be produced by changing the irradiation amount of light in the direction.

Chiral agents whose HTP is changed by light irradiation include those that undergo re-isomerization, dimerization, isomerization and dimerization, etc. by light irradiation.
When the chiral agent has a photoisomerizable group, the photoisomerizable group is preferably an isomerization site of a compound exhibiting photochromic properties, an azo group, an azoxy group, or a cinnamoyl group. Specific compounds include JP-A-2002-080478, JP-A-2002-080851, JP-A-2002-179668, JP-A-2002-179669, JP-A-2002-179670, JP-A-2002- 179681, JP-A-2002-179682, JP-A-2002-338575, JP-A-2002-338668, JP-A-2003-313189, and compounds described in JP-A-2003-313292, etc. can be used.

(Polymerization initiator)
The liquid crystal composition preferably contains a polymerization initiator. In the embodiment in which the polymerization reaction is advanced by ultraviolet irradiation, the polymerization initiator to be used is preferably a photopolymerization initiator capable of initiating the polymerization reaction by ultraviolet irradiation.
Examples of photoinitiators include α-carbonyl compounds (described in US Pat. Nos. 2,367,661 and 2,367,670), acyloin ethers (described in US Pat. No. 2,448,828), α-hydrocarbons substituted aromatic acyloin compounds (described in US Pat. No. 2,722,512), polynuclear quinone compounds (described in US Pat. Nos. 3,046,127 and 2,951,758), triarylimidazole dimers and p-aminophenyl ketone combination (described in US Pat. No. 3,549,367), acridine and phenazine compound (described in JP-A-60-105667, US Pat. No. 4,239,850), acylphosphine oxide compound (JP-B-63-040799, JP-B-5-029234, JP-A-10-095788, JP-A-10-029997, JP-A-2001-233842, JP-A-2000-080068, JP-A-2006-342166, JP-A 2013-114249, JP 2014-137466, JP 4223071, JP 2010-262028, JP 2014-500852), oxime compound (JP 2000-066385, Patent No. No. 4,454,067) and oxadiazole compounds (described in US Pat. No. 4,212,970). For example, paragraphs 0500 to 0547 of JP-A-2012-208494 can also be referred to.

As the polymerization initiator, it is also preferable to use an acylphosphine oxide compound or an oxime compound.
As the acylphosphine oxide compound, for example, a commercially available IRGACURE810 (compound name: bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide) manufactured by BASF Japan Ltd. can be used. Examples of oxime compounds include IRGACURE OXE01 (manufactured by BASF), IRGACURE OXE02 (manufactured by BASF), TR-PBG-304 (manufactured by Changzhou Tenryu Electric New Materials Co., Ltd.), Adeka Arkles NCI-831, and Adeka Arkles NCI-930. (manufactured by ADEKA), ADEKA Arkles NCI-831 (manufactured by ADEKA), and other commercially available products can be used.
Only one polymerization initiator may be used, or two or more polymerization initiators 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.

(crosslinking agent)
The liquid crystal composition may optionally contain a cross-linking agent in order to improve film strength and durability after curing. As the cross-linking agent, one that is cured by ultraviolet rays, heat, humidity, or the like can be preferably used.
The cross-linking agent is not particularly limited and can be appropriately selected depending on the purpose. Examples of cross-linking agents 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; aziridine compounds such as bishydroxymethylbutanol-tris[3-(1-aziridinyl)propionate], 4,4-bis(ethyleneiminocarbonylamino)diphenylmethane; isocyanate compounds such as hexamethylene diisocyanate and biuret type isocyanate; polyoxazoline compounds having chains; alkoxysilane compounds such as vinyltrimethoxysilane and N-(2-aminoethyl)3-aminopropyltrimethoxysilane; In addition, a commonly used catalyst can be used depending on the reactivity of the cross-linking agent, and productivity can be improved in addition to improvement in film strength and durability. These may be used individually by 1 type, and may use 2 or more types together.
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 decrease in stability of the cholesteric liquid crystal layer can be prevented. can be prevented.

(Orientation control agent)
An alignment control agent may be added to the liquid crystal composition to contribute to a stable or rapid planar alignment of the cholesteric liquid crystal layer. Examples of alignment control agents include fluorine (meth)acrylate polymers described in paragraphs [0018] to [0043] of JP-A-2007-272185, paragraphs [0031] to [0031] of JP-A-2012-203237. 0034] and the like, compounds represented by formulas (I) to (IV), and compounds described in JP-A-2013-113913.
As the alignment control agent, one type may be used alone, or two or more types may be used in combination.

The amount of the alignment control agent added in the liquid crystal composition is preferably 0.01 to 10% by mass, more preferably 0.01 to 5% by mass, and more preferably 0.02 to 1% based on the total mass of the polymerizable liquid crystal compound. % by weight is particularly preferred.

(Other additives)
In addition, 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 to make the thickness uniform, and a polymerizable monomer. . In addition, if necessary, the liquid crystal composition may further contain polymerization inhibitors, antioxidants, ultraviolet absorbers, light stabilizers, colorants, metal oxide fine particles, etc. to the extent that the optical performance is not reduced. can be added at

The cholesteric liquid crystal layer comprises a liquid crystal composition obtained by dissolving a polymerizable liquid crystal compound, a polymerization initiator, a chiral agent added as necessary, a surfactant, etc. in a solvent, a transparent substrate, a retardation layer, an alignment layer. Alternatively, it is coated on the cholesteric liquid crystal layer or the like prepared previously, dried to obtain a coating film, and the coating film is irradiated with actinic rays to polymerize the cholesteric liquid crystal composition, and the cholesteric regularity is fixed. cholesteric liquid crystal layer can be formed.
A laminated film composed of a plurality of cholesteric liquid crystal layers can be formed by repeating the above-described manufacturing process of the cholesteric liquid crystal layer.

(solvent)
The solvent used for preparing the liquid crystal composition is not particularly limited and can be appropriately selected according to the purpose, but organic solvents are preferably used.
The organic solvent is not particularly limited and can be appropriately selected depending on the purpose. Examples include ketones, alkyl halides, amides, sulfoxides, heterocyclic compounds, hydrocarbons, esters and ethers and the like. These may be used individually by 1 type, and may use 2 or more types together. Among these, ketones are particularly preferred in consideration of the load on the environment.

(coating, orientation, polymerization)
The method of applying the liquid crystal composition to the transparent substrate, the alignment layer, the underlying cholesteric liquid crystal layer, and the like is not particularly limited, and can be appropriately selected according to the purpose. Examples of coating methods include wire bar coating, curtain coating, extrusion coating, direct gravure coating, reverse gravure coating, die coating, spin coating, dip coating, spray coating, and slide coating. law, etc. It can also be carried out by transferring a liquid crystal composition separately coated on a support.
The liquid crystal molecules are aligned by heating the applied liquid crystal composition. The heating temperature is preferably 200° C. or lower, more preferably 130° C. or lower. By this orientation treatment, an optical thin film is obtained in which the polymerizable liquid crystal compound is twisted so as to have a helical axis in a direction substantially perpendicular to the film surface.

By further polymerizing the oriented liquid crystal compound, the liquid crystal composition can be cured. Polymerization may be either thermal polymerization or photopolymerization using light irradiation, but photopolymerization is preferred. It is preferable to use ultraviolet rays for light irradiation. The irradiation energy is preferably 20 mJ/cm ² to 50 J/cm ² , more preferably 100 to 1,500 mJ/cm ² .
In order to accelerate the photopolymerization reaction, light irradiation may be performed under heating conditions or under a nitrogen atmosphere. The irradiation ultraviolet wavelength is preferably 350 to 430 nm. From the viewpoint of stability, the polymerization reaction rate is preferably as high as 70% or more, more preferably 80% or more. The polymerization reaction rate can be determined by measuring the consumption rate of the polymerizable functional groups by infrared absorption spectrum measurement.

[Polarization conversion layer]
The polarization conversion layer 14 is a layer in which the helical orientation structure of the liquid crystal compound is fixed, and the pitch number x of the helical orientation structure and the film thickness y (unit μm) of the polarization conversion layer satisfy the following relational expressions (a) to (c ) are preferably satisfied.
0.1≦x≦1.0 Formula (a)
0.5≦y≦3.0 Formula (b)
3000≦(1560×y)/x≦50000 Expression (c)
One pitch of the helical structure of the liquid crystal compound corresponds to one turn of the helical structure of the liquid crystal compound.
That is, the pitch number is 1 when the director of the helically aligned liquid crystal compound (long axis direction in the case of rod-like liquid crystal) is rotated by 360°.

When the polarization conversion layer has a helical structure of a liquid crystal compound, it exhibits optical rotation and birefringence with respect to visible light whose wavelength is shorter than the reflection peak wavelength in the infrared region. Therefore, polarization in the visible range can be controlled. By setting the pitch number x of the helically oriented structure of the polarization conversion layer and the film thickness y of the polarization conversion layer within the above ranges, the polarization conversion layer has a function of optically compensating for visible light, or a straight line incident on the reflective film. A function of converting polarized light (p-polarized light) into circularly polarized light can be imparted.

The polarization conversion layer exhibits optical rotation and birefringence with respect to visible light due to the liquid crystal compound having a helical structure that satisfies the relational expressions (a) to (c). In particular, by setting the pitch P of the helical structure of the polarization conversion layer to a length corresponding to the pitch P of the cholesteric liquid crystal layer whose selective reflection center wavelength is in the infrared region with a long wavelength, for visible light with a short wavelength, It exhibits high optical rotation and birefringence.

The relational expression (a) is "0.1≤x≤1.0".
If the pitch number x of the helical structure is less than 0.1, problems such as insufficient optical rotation and birefringence will occur.
On the other hand, if the pitch number x of the helical structure exceeds 1.0, the optical rotatory power and birefringence are excessive, resulting in problems such as failure to obtain desired elliptically polarized light.

The relational expression (b) is "0.5≤y≤3.0".
If the thickness y of the polarization conversion layer is less than 0.5 μm, the film thickness is too thin, resulting in problems such as insufficient optical rotation and birefringence.
If the thickness y of the polarization conversion layer exceeds 3.0 μm, the optical rotation and birefringence are excessive, resulting in problems such as failure to obtain desired circularly polarized light and poor orientation, which is undesirable for manufacturing.

The relational expression (c) is "3000≦(1560×y)/x≦50000".
If “(1560×y)/x” is less than 3000, the optical rotatory power is excessive and the desired polarized light cannot be obtained.
If “(1560×y)/x” exceeds 50000, the optical rotatory power is insufficient, resulting in problems such as failure to obtain desired polarized light.

In the present invention, the pitch number x of the helical structure of the polarization conversion layer is more preferably 0.1 to 0.8, and the film thickness y is more preferably 0.6 μm to 2.6 μm. Further, "(1560×y)/x" is more preferably 5000 to 13000.

That is, the polarization conversion layer preferably has a long spiral structure pitch P and a small pitch number x.
Specifically, the polarization conversion layer preferably has a spiral pitch P equal to the pitch P of the cholesteric liquid crystal layer whose selective reflection central wavelength is in the long wavelength infrared region, and the number of pitches x is small. More specifically, the polarization conversion layer preferably has a spiral pitch P equal to the pitch P of the cholesteric liquid crystal layer having a selective reflection center wavelength of 3000 to 10000 nm, and a small number of pitches x.
In such a polarization conversion layer, the central wavelength of selective reflection corresponding to the pitch P is much longer than that of visible light, so that the above-described optical rotation and birefringence with respect to visible light are more favorably exhibited.

Such a polarization conversion layer can be basically formed in the same manner as a commonly used cholesteric liquid crystal layer. However, when forming the polarization conversion layer, the liquid crystal compound to be used should be such that the pitch number x of the helical structure and the film thickness y [μm] in the polarization conversion layer satisfy all of the relational expressions (a) to (c). , the chiral agent to be used, the amount of the chiral agent added, the film thickness, etc. must be adjusted.

<Layer in which helical alignment structure (helical structure) of liquid crystal compound is fixed>
The layer in which the helical alignment structure (helical structure) of the liquid crystal compound is fixed is a so-called cholesteric liquid crystal layer, and means a layer in which the cholesteric liquid crystal phase is fixed.
The cholesteric liquid crystal layer may be any layer as long as the orientation of the liquid crystal compound in the cholesteric liquid crystal phase is maintained. A cholesteric liquid crystal layer is typically formed by aligning a polymerizable liquid crystal compound in a cholesteric liquid crystal phase, and then polymerizing and curing by ultraviolet irradiation, heating, or the like to form a layer having no fluidity, and at the same time, Any layer may be used as long as it is changed to a state in which the orientation is not changed by an external field or external force. In the cholesteric liquid crystal layer, it is sufficient that the optical properties of the cholesteric liquid crystal phase are maintained in the layer, and the liquid crystal compound in the layer may no longer exhibit liquid crystallinity. For example, the polymerizable liquid crystal compound may be polymerized by a curing reaction and no longer have liquid crystallinity.

As described above, the central wavelength of selective reflection by the cholesteric liquid crystal layer (selective reflection central wavelength) λ depends on the pitch P (= helical period) of the helical structure (helical alignment structure) in the cholesteric liquid crystal phase. It follows the relation of average refractive index n and λ=n×P. As can be seen from this formula, the selective reflection center wavelength can be adjusted by adjusting the n value and/or the P value.

Since the helical 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.
As described above, the cholesteric liquid crystal layer used as the polarization conversion layer has a helical pitch adjusted so that the central wavelength of selective reflection is in the long wavelength infrared region.
The method of forming the cholesteric liquid crystal layer as the polarization conversion layer is basically the same as the method of forming the cholesteric liquid crystal layer described above.

[Retardation layer]
The phase difference layer changes the state of incident polarized light by adding a phase difference (optical path difference) to two orthogonal polarized light components.

In the case where the retardation layer is arranged on the outside of the vehicle for optical compensation, the front retardation of the retardation layer may be a retardation that can be optically compensated.
In this case, the retardation layer preferably has a front retardation of 50 nm to 160 nm at a wavelength of 550 nm.
Further, when the direction corresponding to the vertical direction above the surface of the second glass plate when the windshield glass having the reflective film is attached to the vehicle is 0°, the angle of the slow axis is 10° to 50°. Alternatively, it is preferably -50° to -10°.

Further, when the retardation layer converts linearly polarized light into circularly polarized light, the front retardation of the retardation layer is preferably configured to give λ / 4, and the front retardation is 3 λ / 4 may be provided. Also, the angle of the slow axis may be arranged so as to change the incident linearly polarized light into circularly polarized light.

In this case, the retardation layer preferably has a front retardation of 100 to 450 nm at a wavelength of 550 nm, more preferably 120 to 200 nm or 300 to 400 nm. Further, the direction of the slow axis of the retardation layer is the direction of incidence of projection light for displaying a projected image when the reflective film 10 is used in a head-up display system, and the cholesteric liquid crystal layer constituting the selective reflection layer. is preferably determined according to the sense of the helix of

The retardation layer is not particularly limited and can be appropriately selected according to the purpose. Examples of the retardation layer include a stretched polycarbonate film, a stretched norbornene-based polymer film, an oriented transparent film containing inorganic particles having birefringence such as strontium carbonate, and an inorganic dielectric material on a support. , a film obtained by uniaxially aligning a polymerizable liquid crystal compound and fixing its orientation, and a film obtained by uniaxially orienting a liquid crystal compound and fixing its orientation.

Among them, a film in which a polymerizable liquid crystal compound is uniaxially oriented and oriented and fixed is preferably exemplified as the retardation layer.
Such a retardation layer is formed, for example, by applying a liquid crystal composition containing a polymerizable liquid crystal compound to the surface of a transparent substrate, a temporary support, or an alignment layer, where the polymerizable liquid crystal compound in the liquid crystal composition is added to the liquid crystal. After being formed into a nematic orientation in a state, it can be fixed by curing.
Formation of the retardation layer in this case can be carried out in the same manner as the formation of the cholesteric liquid crystal layer described above, except that the chiral agent is not added to the liquid crystal composition. However, the heating temperature is preferably 50 to 120.degree. C., more preferably 60 to 100.degree.

The retardation layer is formed by coating a composition containing a polymer liquid crystal compound on the surface of a transparent base material, a temporary support, an alignment layer, or the like, forming a nematic alignment in a liquid crystal state, and then fixing this alignment by cooling. It may be a layer obtained by reducing the

Although the thickness of the retardation layer is not limited, it is preferably 0.2 to 300 μm, more preferably 0.5 to 150 μm, even more preferably 1.0 to 80 μm. The thickness of the retardation layer formed from the liquid crystal composition is not particularly limited, but is preferably 0.2 to 10 μm, more preferably 0.5 to 5.0 μm, even more preferably 0.7 to 2.0 μm. .

For the retardation layer, the slow axis is set by tilting, for example, at an angle α with respect to an axis in an arbitrary direction of the retardation layer. The direction of the slow axis can be set, for example, by rubbing the alignment film that is the lower layer of the retardation layer.

The linearly polarized light reflective film may have layers other than the selective reflection layer, the polarization conversion layer, the fluorescent dye layer FL, and the retardation layer. For example, the linearly polarized light reflective film may have a transparent substrate, an adhesive layer, and the like.
For example, in the example shown in FIG. 2, the linearly polarized light reflective film 10A has a transparent substrate 18 arranged on the side of the retardation layer 16 opposite to the selective reflection layer 11 . The transparent substrate 18 supports the retardation layer 16 , the selective reflection layer 11 (cholesteric liquid crystal layer), and the polarization conversion layer 14 . The transparent substrate 18 may be used as a support for forming the retardation layer 16, the selective reflection layer 11 (cholesteric liquid crystal layer), and the polarization conversion layer 14.

The above-mentioned linearly polarized light reflective film may be in the form of a thin film, a sheet, or the like. The linearly polarized light reflective film may be in the form of a roll or the like as a thin film before being used for the windshield glass.

Both the transparent substrate (support) and the adhesive layer are preferably transparent in the visible light region.
Moreover, it is preferable that both the transparent substrate and the adhesive layer have low birefringence. The low birefringence means that the front retardation is 10 nm or less in the wavelength region where the selective reflection layer included in the windshield glass used in the present invention exhibits reflection. This front retardation is preferably 5 nm or less. Furthermore, it is preferable that the support, the adhesive layer, etc. have a small difference in refractive index from the average refractive index (in-plane average refractive index) of the selective reflection layer.

[Transparent substrate]
The transparent substrate can also be used as a substrate when forming a selective reflection layer. The transparent substrate used for forming the selective reflection layer may be a temporary support that is peeled off after the formation of the selective reflection layer. Therefore, the finished reflective film and windshield glass may not contain a transparent substrate. When the finished reflective film or windshield glass contains a transparent substrate instead of being peeled off as a temporary support, the transparent substrate is preferably transparent in the visible light region.

There are no restrictions on the material of the transparent substrate. Examples of transparent substrates include polyesters such as polyethylene terephthalate (PET), polycarbonates, acrylic resins, epoxy resins, polyurethanes, polyamides, polyolefins, cellulose derivatives, and plastic films such as silicones. As the temporary support, glass may be used in addition to the plastic film described above.

The thickness of the transparent substrate may be about 5.0 to 1000 μm, preferably 10 to 250 μm, more preferably 15 to 90 μm.

Here, as in the example shown in FIG. 2, when the transparent base material 18 is arranged on the side of the second glass plate 28, that is, on the inside of the vehicle, the transparent base material 18 may contain an ultraviolet absorber. preferable.
By including an ultraviolet absorber in the transparent base material 18, deterioration of the reflective film (selective reflection layer) due to ultraviolet rays can be suppressed.

[1-2] Linearly Polarized Reflective Film FIG. 3 is a schematic diagram showing an example of the windshield glass used in the present invention. It consists of a selective reflection layer (dielectric multilayer film) in which (13Ra, 13Ga, 13Ba) and optically isotropic layers (13Rb, 13Gb, 13Ba) are alternately laminated. In the illustrated example, the linearly polarized light reflecting film 10B includes a first laminated portion 13R (R layer) in which an optically anisotropic layer 13Ra and an optically isotropic layer 13Rb are alternately laminated, an optically anisotropic layer 13Ga and an optical layer 13Rb. A second lamination portion 13G (G layer) in which the anisotropic layers 13Gb are alternately laminated, and a third lamination portion 13B (B layer) in which the optically anisotropic layers 13Ba and the optically isotropic layers 13Bb are alternately laminated. have
The dielectric multilayer film includes the above three wavelengths λ _B , λ _G and λ _R as selective reflection center wavelengths for light with an incident angle of 60°.
In the reflective film of the present invention, any one of the dielectric multilayer films constituting the dielectric multilayer film may contain a fluorescent dye. A layer (fluorescent dye layer FL) may be provided. Further, when two or more kinds of fluorescent dyes are contained, the form in which the fluorescent dye is contained in any one of the dielectric multilayer films constituting the dielectric multilayer film and the form in which the fluorescent dye layer FL is provided are used in combination. may have been A fluorescent dye layer FL is provided so as to contain a fluorescent dye in the dielectric multilayer film positioned on the outermost surface side of the dielectric multilayer film and/or to be positioned on one of the surfaces of the dielectric multilayer film. Preferably, among the dielectric multilayer films, the dielectric multilayer film located on the outermost side of the vehicle contains a fluorescent dye, and/or the surface of the dielectric multilayer film located on the vehicle exterior side, It is more preferable to provide a fluorescent dye layer FL.
In FIG. 3, on the first lamination part 13R (meaning between the first lamination part 13R and the intermediate film 36 or between the first lamination part 13R and the second lamination part 13G, preferably the first lamination part 13R) Between the laminated portion 13R and the intermediate film 36), the above-described fluorescent dye layer FL (not shown) is provided.

The thicknesses of the optically anisotropic layers and the optically isotropic layers of the first laminated section 13R, the second laminated section 13G and the third laminated section 13B are different from each other. Also, the number of layers, the refractive index, and the like may be different.

In the linearly polarized reflective film, the refractive index n _e1 in the slow axis direction of the optically anisotropic layer exceeds the refractive index n _o2 of the optically isotropic layer (that is, n _e1 >n _o2 ), and the optical The refractive index _no1 in the direction perpendicular to the slow axis of the anisotropic layer is substantially the same as the refractive index _no2 of the optically isotropic layer.
A plurality of optically anisotropic layers are laminated such that the slow axes thereof are parallel to each other. Therefore, as shown in FIG. 4, in one direction (vertical direction in FIG. 4), a layer having a high refractive index (n _e1 ) and a layer having a low refractive index (n _o2 ) are laminated. . On the other hand, in the direction orthogonal to this direction (horizontal direction in FIG. 4), layers having the same refractive index are laminated.

A film in which layers with a low refractive index (low refractive index layers) and layers with a high refractive index (high refractive index layers) are alternately laminated has a structural structure between many low refractive index layers and high refractive index layers. Interference is known to reflect certain wavelengths of light. Therefore, the linearly polarized light reflecting film 10B shown in FIGS. 3 and 4 reflects linearly polarized light in the vertical direction in FIG. 4 and transmits linearly polarized light in the horizontal direction.

Here, the dielectric multilayer film used in the HUD system of the present invention includes the above three wavelengths λ _B , λ _G and λ _R as selective reflection center wavelengths for light with an incident angle of 60°. In the linearly polarized light reflecting film 10B shown in FIG. 3, the fluorescent dye layer FL (not shown) described above is provided on the first laminated portion 13R.

In the dielectric multilayer film, the selective reflection central wavelength and the reflectance can be adjusted by adjusting the refractive index difference between the low refractive index layer and the high refractive index layer, the thickness, the number of layers, and the like. In the example shown in FIG. 3, mainly the first lamination part 13R realizes reflection with λ _R for light with an incident angle of 60°, and the second lamination part 13G realizes reflection with λ R for light with an incidence angle of 60°. Reflection with λ _G is realized, and reflection with λ _B for light with an incident angle of 60° is realized by the third lamination portion 13B.

In the above dielectric multilayer film, the reflection peak having the selective reflection central wavelength determined by the above-described method has a maximum value with a difference of 2% or more from the adjacent minimum value, and a half value width of 10 to 10. Let the peak be at 200 nm.

As described above, the selective reflection center wavelength and reflectance in the dielectric multilayer film can be adjusted by the refractive index difference, thickness, lamination layers, etc. between the low refractive index layer and the high refractive index layer. Specifically, by setting the thickness d of the low refractive index layer and the high refractive index layer to d=λ/(4×n) from the wavelength λ of the reflected light and the refractive index n, the selective reflection center Wavelength can be adjusted. In addition, since the reflectance increases as the number of layers of the low refractive index layer and the number of the high refractive index layers increases, the reflectance can be adjusted by adjusting the number of layers. Further, the half width of the reflection peak having the selective reflection center wavelength can be adjusted by the refractive index difference between the low refractive index layer and the high refractive index layer.

Here, the half width of the reflection peak having each selective reflection center wavelength depends on the difference between the refractive index in the slow axis direction of the optically anisotropic layer and the refractive index of the optically isotropic layer, and the refractive index difference is The larger the value, the larger the half width. Moreover, when reflection peaks with low reflectance are at close wavelengths, interference occurs, causing a phenomenon in which the reflection peaks become too strong or too weak. Appropriately adjusting the half width of the reflection peak having each selective reflection center wavelength to improve the brightness of the displayed image while increasing the transmittance, and reducing the influence of interference with adjacent reflection peaks. Therefore, the difference between the refractive index in the slow axis direction of the optically anisotropic layer and the refractive index of the optically isotropic layer is preferably 0.03 to 0.20, more preferably 0.05 to 0.14. and more preferably 0.05 to 0.10.

Further, the dielectric multilayer film is composed of a light reflecting layer having λ _B , a light reflecting layer having λ _G , and a light reflecting layer having λ _R as a selective reflection center wavelength for light with an incident angle of 60°, These light reflecting layers are preferably in contact with each other. For example, in the example shown in FIG. 3, the first laminated portion 13R having λ _R for light with an incident angle of 60° and the second laminated portion 13G having λ _G for light with an incident angle of 60° are in contact with each other. In addition, the second laminated portion 13G having λ _G for light with an incident angle of 60° and the third laminated portion 13B having λ _B for light with an incident angle of 60° are in contact with each other. The first lamination portion 13R, the second lamination portion 13G, and the third lamination portion 13B are light reflection layers that constitute dielectric multilayer films (selective reflection layers) used in the HUD system of the present invention.

Although not shown in FIG. 3, in addition to the three laminated portions 13R, 13G, and 13B, an optical system having a selective reflection center wavelength of 300 nm or more and less than 400 nm for light with an incident angle of 60° It is also preferable to include a selective reflection layer (hereinafter referred to as a light reflection layer UV) formed by laminating an anisotropic layer and an optically isotropic layer from the viewpoint of suppressing reflected color.
By providing the light reflecting layer UV, when the windshield glass is configured to include a circularly polarized light reflecting layer and a retardation layer, which will be described later, as described above, it is confirmed when the windshield glass is observed under external light. It is possible to suppress the tint (especially the yellow tint in the reflected tint for light with an incident angle of 5°).

If the light reflecting layers having respective selective reflection central wavelengths for light with an incident angle of 60° are spaced apart from each other, the film thickness between the layers becomes thicker, making it difficult to obtain the effect of interference of the light reflected by each light reflecting layer. Become. On the other hand, by adopting a structure in which the light reflecting layers are in contact with each other, the half width of the reflection peak having each selective reflection center wavelength can be narrowed by the effect of interference of light reflected by each light reflecting layer. can be done.

The above-mentioned linearly polarized light reflective film may be in the form of a thin film, a sheet, or the like. The linearly polarized light reflective film may be in the form of a roll or the like as a thin film before being used for windshield glass.

Materials and methods for manufacturing the dielectric multilayer film can be those described in, for example, Japanese Patent Publication No. 9-506837. Specifically, a wide variety of materials can be used to form dielectric multilayer films when processed under conditions selected to obtain refractive index relationships. In general, it is required that the first material has a different refractive index than the second material in the chosen direction. This refractive index difference can be achieved in a variety of ways, including stretching, extrusion, or coating during film formation or after film formation. Additionally, it is preferred that the two materials have similar rheological properties (eg, melt viscosity) so that they can be coextruded.

Materials particularly suitable for use in the dielectric multilayer film include PEN (polyethylene naphthalate) and PET (polyethylene terephthalate) as materials for the optically anisotropic layer, and (isotropic polymethyl methacrylate), PEN, PET and PMMA (polymethyl methacrylate resin).

As described above, the linearly polarized light reflecting film (dielectric multilayer film) used in the HUD system of the present invention has three wavelengths of λ _B , λ _G and λ _R as the selective reflection center wavelengths for light with an incident angle of 60°. In order to obtain a structure having two wavelengths, it is preferable to have three laminated portions in which the thicknesses of the optically anisotropic layer and the optically isotropic layer are different. In the present invention, after each of the three laminated parts is formed by the above-described stretching, extrusion molding, or the like, the laminated parts are bonded together to produce a linearly polarized light reflecting film (dielectric multilayer film). Alternatively, the thickness before processing may be adjusted so that three laminated portions having different thicknesses are formed, and the three laminated portions may be integrally formed by stretching, extrusion molding, or the like.

The thickness of the dielectric multilayer film is preferably 2.0-50 μm, more preferably 8.0-30 μm.

A linearly polarized light reflective film has a selective reflection layer (dielectric multilayer film) formed by laminating an optically anisotropic layer and an optically isotropic layer, and contains a fluorescent dye. The linearly polarized light reflective film may have a structure including a retardation layer, a polarization conversion layer, a support, an adhesive layer, etc., in addition to the dielectric multilayer film.

The retardation layer, polarization conversion layer, support (transparent substrate), and adhesive layer used in the linearly polarized light reflective film described above include the retardation layer, polarization conversion layer, and transparent layer used in the linearly polarized light reflective film described above. The description of the substrate (support) and adhesive layer can be applied.

Below, among the constituent elements of the windshield glass, the glass plate (laminated glass), the intermediate layer, and the heat seal layer (adhesive layer) will be described in order as constituent elements other than the above-mentioned reflective film.

[2] Laminated glass The windshield glass may have a structure of laminated glass. Preferably, the windshield glass used in the HUD system of the present invention is laminated glass and has the above-described reflective film between the first glass plate and the second glass plate.
The windshield glass may have a configuration in which a reflective film is arranged between the first glass plate and the second glass plate. However, the windshield glass has an intermediate film (intermediate film sheet) provided between at least one of the first glass plate and the reflective film and between the reflective film and the second glass plate. is preferred.
In the windshield glass, as an example, as shown in FIG. 1, the first glass plate 30 is arranged on the opposite side (outside the vehicle) of the image viewing side in the HUD system, and the second glass plate 28 is It is arranged on the viewing side (inside the vehicle). In addition, in the windshield glass used in the HUD system of the present invention, the first and second in the first glass plate and the second glass plate have no technical meaning, and distinguish between the two glass plates. This is provided for convenience. Therefore, the second glass plate may be on the vehicle exterior side and the first glass plate may be on the vehicle interior side.
As the glass plates such as the first glass plate and the second glass plate, glass plates commonly used for windshield glass can be used. For example, a glass plate having a visible light transmittance of 80% or less such as 73% or 76%, such as green glass with high heat shielding properties, may be used. Even when such a glass plate with a low visible light transmittance is used, by using the above-mentioned reflective film, a windshield glass having a visible light transmittance of 70% or more even at the position of the reflective film can be obtained. can be made.

The thickness of the glass plate is not particularly limited, but may be about 0.5 to 5.0 mm, preferably 1.0 to 3.0 mm, more preferably 2.0 to 2.3 mm. The materials or thicknesses of the first glass plate and the second glass plate may be the same or different.

A windshield glass having a structure of laminated glass can be produced by a conventional method for producing laminated glass.
In general, after sandwiching an interlayer film for laminated glass between two glass plates, heat treatment and pressure treatment (treatment using a rubber roller, etc.) are repeated several times, and finally an autoclave or the like is used. It can be produced by a method of performing heat treatment under pressurized conditions.

A windshield glass having a structure of laminated glass having a reflective film and an intermediate film may be produced, for example, by forming a reflective film on the surface of a glass plate and then using the method for producing laminated glass described above. The intermediate film for laminated glass containing the reflective film of No. 1 may be used to produce the laminated glass by the method for producing the laminated glass described above.
When the reflective film is formed on the surface of the glass plate, the glass plate on which the reflective film is provided may be the first glass plate or the second glass plate. In this case, the reflective film may be bonded to the glass plate with an adhesive (heat seal layer), for example.

[3] Intermediate film Intermediate film 36 prevents glass from penetrating into the interior of the vehicle and scattering in the event of an accident. In the example shown in FIG. In the example shown in FIG. 2, the linearly polarized light reflecting film 10A and the first glass plate 30 are adhered, and in the example shown in FIG. The glass plate 28 and the first glass plate 30 are adhered.

Any intermediate film commonly used as an intermediate film (intermediate layer) in laminated glass can be used as the intermediate film (intermediate film sheet). For example, a resin film containing a resin selected from the group consisting of polyvinyl butyral (PVB), ethylene-vinyl acetate copolymer and chlorine-containing resin can be used. The resin described above is preferably the main component of the intermediate film. In addition, being a main component means the component which occupies 50 mass % or more of an intermediate film.

Among the above resins, polyvinyl butyral and ethylene-vinyl acetate copolymer are preferred, and polyvinyl butyral is more preferred. The resin is preferably a synthetic resin.
Polyvinyl butyral can be obtained by acetalizing polyvinyl alcohol with butyraldehyde. A preferable lower limit of the degree of acetalization of polyvinyl butyral is 40%, a preferable upper limit is 85%, a more preferable lower limit is 60%, and a more preferable upper limit is 75%.

Polyvinyl alcohol is generally obtained by saponifying polyvinyl acetate, and polyvinyl alcohol having a degree of saponification of 80 to 99.8 mol % is generally used.
The preferred lower limit of the degree of polymerization of polyvinyl alcohol is 200, and the preferred upper limit is 3,000. When the degree of polymerization of polyvinyl alcohol is 200 or more, the penetration resistance of the resulting laminated glass is less likely to decrease. Good workability. A more preferable lower limit is 500, and a more preferable upper limit is 2,000.

Also, the thickness of the intermediate film 36 is not limited, and the thickness may be set in accordance with the forming material, etc., in the same manner as the intermediate film of the commonly used windshield glass.

In FIG. 1, the windshield glass 24 has a heat seal layer 38 provided between the reflective film 10 and the second glass plate 28, and the reflective film 10 and the first glass plate 30 are bonded with an intermediate film 36. wearing, but not limited to. That is, a heat seal layer may be provided between the reflective film 10 and the first glass plate 30 and an intermediate film may be provided between the reflective film 10 and the second glass plate 28 .
In addition, the windshield glass 24 is configured without the intermediate film 36, and the adhesion between the reflective film 10 and the second glass plate 28 and the adhesion between the reflective film 10 and the first glass plate 30 are A configuration using the heat seal layer 38 may be used.

(Intermediate film including reflective film)
An intermediate film for laminated glass containing a reflective film can be formed by bonding a reflective film to the surface of the intermediate film described above. Alternatively, the reflective film can be sandwiched between the two intermediate films described above. The two intermediate films may be the same or different, but are preferably the same.
A conventional bonding method can be used for bonding the reflective film and the intermediate film, but it is preferable to use a lamination treatment. The lamination process is preferably carried out under a certain degree of heat and pressure conditions so that the laminate (reflective film) and the intermediate film are not separated after processing.
In order to perform lamination stably, the film surface temperature of the adhesive side of the intermediate film is preferably 50 to 130.degree. C., more preferably 70 to 100.degree.
It is preferable to apply pressure during lamination. The pressurization conditions are not limited, but are preferably less than 2.0 kg/cm ² (less than 196 kPa), more preferably 0.5 to 1.8 kg/cm ² (49 to 176 kPa), and 0.5 to 1.5 kg. /cm ² (49 to 147 kPa) is more preferable.

Moreover, when the reflective film has a support (transparent substrate), the support may be peeled off simultaneously with lamination, immediately after lamination, or immediately before lamination. That is, the reflective film attached to the intermediate film obtained after lamination may be free of a support.
An example of a method for producing an intermediate film containing a reflective film is
(1) A first step of bonding a reflective film to the surface of the first intermediate film to obtain a first laminate, and
(2) A second step of bonding a second intermediate film to the surface of the reflective film in the first laminate opposite to the surface to which the first intermediate film is bonded.
For example, in the first step, the reflective film and the first intermediate film are bonded without facing the support and the first intermediate film. The support is then peeled off from the reflective film. Furthermore, in the second step, a second intermediate film is attached to the surface from which the support has been peeled off. This makes it possible to produce an interlayer containing a reflective film that does not have a support. In addition, by using an intermediate film containing this reflective film, a laminated glass in which the reflective film does not have a support can be easily produced.
In order to stably peel the support without damage, the temperature of the support when peeling the support from the reflective film is preferably 40°C or higher, more preferably 40 to 60°C.

[4] Heat seal layer (adhesive layer)
The heat seal layer (adhesive layer) 38 is a layer made of, for example, a coating type adhesive. In the example shown in FIG. 2, the linearly polarizing reflective film 10A is adhered to the second glass plate 28 with a heat seal layer 38. In the example shown in FIG. In the windshield glass used in the present invention, instead of the heat seal layer 38, the linearly polarized light reflecting film 10A may be attached to the second glass plate 28 by an intermediate film. In addition, when the linearly polarized light reflecting film 10A is smaller than the intermediate film 36 that bonds the first glass plate 30 and the linearly polarized light reflecting film 10A, the intermediate film 36 separates the linearly polarized light reflecting film 10A from the second layer. may be attached to the glass plate 28 of the

There are no restrictions on the heat seal layer 38, and various commonly used materials can be used as long as they can ensure the transparency required for the windshield glass 24 and can adhere the reflective film 10 and the glass with the necessary adhesion force. are available. The same material as the intermediate film 36 such as PVB may be used for the heat seal layer 38 . In addition to this, the heat seal layer 38 may be made of an acrylate adhesive or the like.

The heat seal layer 38 may be formed from an adhesive.
Adhesives include hot-melt type, heat-curing type, photo-curing type, reaction-curing type, and pressure-sensitive adhesive type that does not require curing from the viewpoint of curing methods. In addition, adhesives of any type are made of acrylate, urethane, urethane acrylate, epoxy, epoxy acrylate, polyolefin, modified olefin, polypropylene, ethylene vinyl alcohol, vinyl chloride, Compounds such as chloroprene rubber-based, cyanoacrylate-based, polyamide-based, polyimide-based, polystyrene-based, and polyvinyl butyral-based compounds can be used.
From the viewpoint of workability and productivity, a light-curing type is preferable as the curing method, and from the viewpoint of optical transparency and heat resistance, it is possible to use acrylate, urethane acrylate, epoxy acrylate, etc. as the material. preferable.

The heat seal layer 38 may be formed using a highly transparent adhesive transfer tape (OCA tape). As the highly transparent adhesive transfer tape, a commercially available product for image display devices, particularly a commercially available product for the surface of the image display portion of the image display device may be used. Examples of commercially available products include adhesive sheets (PD-S1, etc.) manufactured by Panac Co., Ltd., MHM series adhesive sheets manufactured by Nichiei Kako Co., Ltd., and the like.

The thickness of the heat seal layer 38 is also not limited. Therefore, the thickness that provides sufficient adhesive strength may be appropriately set according to the material forming the heat seal layer 38 .
Here, if the heat seal layer 38 is too thick, it may not be possible to adhere the reflective film 10 to the second glass plate 28 or the first glass plate 30 while maintaining sufficient flatness. Considering this point, the thickness of the heat seal layer 38 is preferably 0.1 to 800 μm, more preferably 0.5 to 400 μm.

The heat seal layer 38 preferably has a surface roughness Sa1 of 40 nm or less at a viewing angle of 3700 μm×4900 μm and a surface roughness Sa2 of 7 nm or more at a viewing angle of 180 μm×240 μm.

<Projector>
A "projector" is a "device for projecting light or an image", including a "device for projecting a rendered image", that emits projection light carrying an image to be displayed. In the HUD system of the present invention, the projector is a projector that emits p-polarized projection image light.
In a HUD system, the projector may be positioned so that the p-polarized projection light carrying the image to be displayed is incident at an oblique angle of incidence on the reflective film in the windshield glass.

In the HUD system, the projector preferably includes a drawing device and reflects and displays an image (real image) drawn on a small intermediate image screen by a combiner as a virtual image.
For the projector, for example, when p-polarized projection light is emitted, a commonly used projector used for a HUD system can be used. Further, it is preferable that the projector has a variable imaging distance of the virtual image, ie, a variable imaging position of the virtual image.

Methods for changing the imaging distance of the virtual image in the projector include, for example, a method of moving the image generation surface (screen) (see Japanese Patent Application Laid-Open No. 2017-21302), and a method of switching and using a plurality of optical paths with different optical path lengths. (see WO2015/190157), a method of changing the optical path length by inserting and/or moving a mirror, a method of changing the focal length by using a combined lens as an imaging lens, a method of moving the projector 22, and forming a virtual image. Examples include a method of switching and using a plurality of projectors with different distances, a method of using a variable focus lens (see WO2010/116912), and the like.

Note that the projector may be one in which the imaging distance of the virtual image can be changed continuously, or one in which the imaging distance of the virtual image can be switched between two or three or more points.
Here, it is preferable that at least two virtual images out of the virtual images of the light projected by the projector are different in imaging distance by 1 m or more. Therefore, if the projector can continuously change the imaging distance of the virtual image, it is preferable that the imaging distance of the virtual image can be changed by 1 m or more. By using such a projector, it is preferable in that it is possible to appropriately cope with cases where the distance of the driver's line of sight differs greatly, such as driving at normal speed on a general road and driving at high speed on a highway. .

(drawing device)
A rendering device may itself be a device that displays an image, or it may be a device that emits light capable of rendering an image.
In the drawing device, the light from the light source may be adjusted by a drawing method such as an optical modulator, laser luminance modulation means, or light deflection means for drawing. A drawing device means a device that includes a light source and, depending on the drawing method, an optical modulator, a laser luminance modulation means, or an optical deflection means for drawing.

(light source)
The light source used in the HUD system of the present invention is not particularly limited, and commonly-used laser light sources used in projectors, drawing devices, displays, etc. can be used, and semiconductor lasers are preferably used.
For example, when a semiconductor laser is used as a laser light source, the peak emission wavelength of blue laser light is 450±10 nm, the peak emission wavelength of green laser light is 518±7 nm, and the peak wavelength of green laser light is 518±7 nm. The peak wavelength of emitted light is generally 638±5 nm.
The absolute value of the difference between the peak wavelength of the emission wavelength of the blue laser light and λ _B in the selective reflection layer is usually 10 nm or less, preferably 5 nm or less.
Similarly, the absolute value of the difference between the peak wavelength of the emission wavelength of green laser light and λ _G in the selective reflection layer is usually 7 nm or less, preferably 4 nm or less.
Similarly, the absolute value of the difference between the peak wavelength of the emission wavelength of the red laser light and λ _R in the selective reflection layer is usually 5 nm or less, preferably 3 nm or less.

(drawing method)
The drawing method can be selected according to the laser light source that emits the three colors of blue, green, and red laser light, and examples thereof include a scanning method using a laser.

The scanning method is a method in which a light beam is scanned on a screen and an image is formed using an afterimage of the eye. In the scanning method using a laser, brightness-modulated laser beams of, for example, red, green, and blue colors are bundled into a single beam by a combining optical system, a condenser lens, or the like, and the beam is converted into light. It is sufficient that the image is scanned by the deflection means and drawn on an intermediate image screen, which will be described later.
In the scanning method, for example, the luminance modulation of each color laser light such as red light, green light, and blue light may be performed directly as intensity change of the light source, or may be performed by an external modulator. Examples of the light deflection means include a galvanomirror, a combination of a galvanomirror and a polygon mirror, and MEMS (Micro Electro Mechanical Systems), among which MEMS is preferred. Scanning methods include a random scan method, a raster scan method, and the like, and it is preferable to use the raster scan method. In a raster scan scheme, the laser light can be driven, for example, with a resonant frequency in the horizontal direction and a sawtooth wave in the vertical direction. Since the scanning method does not require a projection lens, it is easy to reduce the size of the device.
Among them, a light source module having blue, green, and red laser light sources irradiates RGB light onto a biaxial MEMS mirror, and drives the MEMS mirror at high speed to form an image on an intermediate image screen with RGB reflected light. A raster scan method for drawing is common.

Light emitted from the drawing device may be linearly polarized light or natural light (non-polarized light).
A drawing device using a laser light source essentially emits linearly polarized light. In the case of a drawing device whose emitted light is linearly polarized light and the emitted light includes light of a plurality of wavelengths (colors), the polarization directions (transmission axis directions) of the light of the plurality of wavelengths are preferably the same. It is known that some commercially available drawing devices do not have a uniform polarization direction in the wavelength regions of red, green, and blue emitted light (see Japanese Patent Application Laid-Open No. 2000-221449). Specifically, an example is known in which the polarization direction of green light is orthogonal to the polarization direction of red light and the polarization direction of blue light.
In addition, in the HUD system of the present invention, the projection light emitted from the projector is p-polarized light.

(intermediate image screen)
As mentioned above, the rendering device may use an intermediate image screen. An "intermediate image screen" is a screen on which an image is drawn. That is, when the light emitted from the rendering device is not yet visible as an image, the rendering device forms a visible image on the intermediate image screen with this light. The image rendered on the intermediate image screen may be projected onto the combiner by light transmitted through the intermediate image screen, or may be reflected onto the intermediate image screen and projected onto the combiner.

Examples of intermediate image screens include scattering films, microlens arrays, and screens for rear projection. In the case where a plastic material is used as the intermediate image screen, if the intermediate image screen has birefringence, the plane of polarization and light intensity of the polarized light incident on the intermediate image screen are disturbed, resulting in color unevenness, etc. in the combiner (reflection film). However, the problem of color unevenness can be reduced by using a retardation film having a predetermined retardation.
The intermediate image screen preferably has the function of spreading and transmitting the incident light. This is because the projected image can be enlarged and displayed. Such intermediate image screens include, for example, screens composed of microlens arrays. Microarray lenses used in HUD systems are described, for example, in JP-A-2012-226303, JP-A-2010-145745, and JP-A-2007-523369. The projector may include a reflector or the like that adjusts the optical path of the projection light formed by the drawing device.

HUD systems using windshield glass as a reflective film are described in JP-A-2-141720, JP-A-10-96874, JP-A-2003-98470, US Pat. 2006-512622 and the like can be referred to.

[Projection light (incident light)]
Incident light is preferably incident at an oblique incident angle of 45° to 70° with respect to the normal to the reflective film. The Brewster angle at the interface between glass with a refractive index of about 1.51 and air with a refractive index of 1 is about 56°. The amount of reflected light from the surface of the windshield glass on the viewing side is less than that of the selective reflection layer of (1), and image display with little influence of double images is possible.
It is also preferred that said angle is between 50° and 65°. At this time, the projected image can be observed on the incident side of the projected light at an angle of 45° to 70°, preferably 50° to 65°, on the side opposite to the incident light with respect to the normal line of the selective reflection layer. Any configuration can be used.

The incident light may be incident from any direction, such as the top, bottom, left, or right of the windshield glass, and may be determined according to the viewing direction. For example, a configuration in which light is incident from below at the time of use at an oblique incident angle as described above is preferable.
Also, the reflective film of the windshield glass is arranged to reflect incident p-polarized light.

As described above, the projected light when displaying a projected image in the HUD system of the present invention is p-polarized light that oscillates in a direction parallel to the plane of incidence.
If the light emitted from the projector is not linearly polarized light, it may be p-polarized by providing a linear polarizing film (polarizer) on the side of the light emitted from the projector. p-polarized light may be obtained by a conventional method using, for example, In this case, a member that converts non-linearly polarized projection light into p-polarized light is also considered to constitute the projector in the HUD system of the present invention.
As described above, for projectors where the polarization direction in the wavelength regions of red, green, and blue emitted light is not uniform, the polarization direction is adjusted in a wavelength-selective manner, and all color wavelength regions are converted to p-polarized light. make it incident.

As described above, the HUD system (projector) may be a projection system in which the virtual image forming position is variable. By making the virtual image forming position variable, the driver can visually recognize the virtual image more comfortably and conveniently.
The virtual image formation position is a position where the driver of the vehicle can visually recognize the virtual image, for example, a position 1000 mm or more beyond the windshield glass as viewed from the driver.

In FIG. 1, the vertical direction Y of the windshield glass 24 is the direction corresponding to the vertical direction of the vehicle or the like in which the windshield glass 24 is arranged, and is defined as the ground side being the lower side and the opposite side being the upper side. is. When the windshield glass 24 is installed in a vehicle or the like, the windshield glass 24 may be arranged at an angle due to the structure or design. direction. The surface is the exterior side of the vehicle.

The present invention is basically configured as described above. Although the HUD system of the present invention and its component elements such as the windshield glass and the reflective film have been described in detail above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention. may of course be improved or changed.

The present invention will be described in more detail below based on examples. The materials, amounts used, proportions, treatment details, treatment procedures, etc. shown in the following examples can be changed as appropriate without departing from the gist of the present invention. Therefore, the scope of the present invention should not be construed to be limited by the specific examples shown below.
In the following examples, "parts" and "%" representing compositions are based on mass unless otherwise specified. Also, room temperature means "25°C".

<Preparation of Quantum Dot-Containing Polymerizable Composition and Coating Liquid for Forming Selective Reflection Layer, Production of Dielectric Multilayer Film>
(Example 1)
[Preparation of quantum dot-containing polymerizable composition]
The following components were mixed so as to have the composition ratio shown below, filtered through a polypropylene filter with a pore size of 0.2 μm, and dried under reduced pressure for 30 minutes to prepare a quantum dot-containing polymerizable composition 1.
Toluene dispersion of quantum dots 1 (emission peak wavelength: 490 nm) 10 parts by mass Lauryl methacrylate 80.8 parts by mass Trimethylolpropane triacrylate 18.2 parts by mass Photopolymerization initiator (Irgacure 819 (trade name, BASF company)) 1 part by mass

In the above, the quantum dots 1 in the “toluene dispersion of quantum dots 1” are core/shell-type quantum dots (average particle diameter: 3.9 nm, aspect ratio ( Long axis/short axis)=1), and the concentration of the quantum dots 1 with respect to the total amount of the toluene dispersion was 1% by mass.

[Preparation of Coating Liquid for Forming Cholesteric Liquid Crystal Layer]
Each cholesteric liquid crystal layer (UV layer, B layer, G A coating solution for forming a narrow-band cholesteric liquid crystal layer was prepared by mixing the following components so as to have the composition ratio shown below.
Rod-shaped liquid crystal compound 101 55 parts by mass Rod-shaped liquid crystal compound 102 30 parts by mass Rod-shaped liquid crystal compound 201 13 parts by mass Rod-shaped liquid crystal compound 202 2 parts by mass Polymerization initiator IRGACURE OXE01 (trade name, manufactured by BASF) 1.0 mass Parts Alignment control agent 1 (fluorine-based horizontal alignment agent 1) 0.01 parts by mass Alignment control agent 3 (fluorine-based horizontal alignment agent 3) 0.01 mass parts Right-handed chiral agent Paliocolor LC756 (trade name, manufactured by BASF)
Adjust according to the target selective reflection central wavelength ・Solvent (methyl ethyl ketone) Amount that makes the solute concentration 20% by mass

Rod-shaped liquid crystal compound 101:

  Rod-shaped liquid crystal compound 102:

  Rod-shaped liquid crystal compounds 201 and 202:

  Orientation control agent 1:

Orientation control agent 3:

[Preparation of coating solution for forming quantum dot-containing cholesteric liquid crystal layer]
The quantum dot-containing polymerizable composition 1 prepared above is mixed with the coating liquid for forming the cholesteric liquid crystal layer (R layer) prepared above so that the concentration of the quantum dots in the mixed composition is 1% by mass. Then, a coating liquid 1 for forming a quantum dot-containing cholesteric liquid crystal layer was prepared.

(Example 2 and Example 3)
[Preparation of Coating Liquid for Forming Cholesteric Liquid Crystal Layer]
The coating solution for forming each cholesteric liquid crystal layer (UV layer, B layer, G layer, R layer) prepared in Example 1 was used as it was.
Therefore, the quantum dot-containing polymerizable composition 1 was not added to the cholesteric liquid crystal layer-forming coating liquids according to Examples 2 and 3.

(Example 4)
[Preparation of quantum dot-containing polymerizable composition 2]
In the preparation of the quantum dot-containing polymerizable composition 1 in Example 1, instead of the "quantum dot 1 toluene dispersion (emission peak wavelength: 490 nm)", "quantum dot 2 toluene dispersion (emission peak wavelength: 590 nm )” was used to prepare a quantum dot-containing polymerizable composition 2 in the same manner as the quantum dot-containing polymerizable composition 1 in Example 1.
In the above, the quantum dots 2 in the “toluene dispersion of quantum dots 2” are core/shell quantum dots (average particle diameter: 6.1 nm, aspect ratio ( Long axis/short axis)=1), and the concentration of the quantum dots 2 with respect to the total amount of the toluene dispersion was 1% by mass.

[Preparation of coating solution for forming quantum dot-containing cholesteric liquid crystal layer]
The coating liquid for forming the cholesteric liquid crystal layer (R layer) prepared in Example 1 was mixed with the quantum dot-containing polymerizable composition 1 prepared in Example 1 and the quantum dot-containing polymerizable composition 2 prepared above, A coating liquid 2 for forming a quantum dot-containing cholesteric liquid crystal layer was prepared.
The quantum dots 1 and 2 were mixed so that the concentration of the quantum dots in the coating liquid 2 for forming the quantum dot-containing cholesteric liquid crystal layer was 1 mass % and 1 mass %, respectively.

[Preparation of Coating Liquid for Forming Cholesteric Liquid Crystal Layer]
The cholesteric liquid crystal layer-forming coating solution for forming each cholesteric liquid crystal layer (UV layer, B layer, G layer) prepared in Example 1 was used as it was.

(Example 5)
[Fabrication of Dielectric Multilayer Film]
Based on the method described in Japanese Patent Application Laid-Open No. 9-506837, a linearly polarized light reflecting film composed of a dielectric multilayer film was produced as follows.

2,6-polyethylene naphthalate (PEN) and a copolyester of 70 mole % naphthalate and 30 mole % terephthalate (coPEN) were synthesized in a standard polyester resin synthesis reactor using ethylene glycol as the diol.
The resulting monolayer films of PEN and coPEN were extruded, stretched at about 150°C at a draw ratio of 5:1, and heat treated at about 230°C for 30 seconds. As a result of this stretching heat treatment, the PEN film has a refractive index about 1.86 about the retardation axis (orientation axis) and a refractive index about 1.64 about the transverse axis, making the coPEN film isotropic and having a refractive index of about 1.86. Confirmed to be 64.

Then, by adjusting the draw ratio, the PEN film has a refractive index about 1.71 for the slow axis and a refractive index about 1.64 for the transverse axis, and the coPEN film is isotropic, with a refractive index of about It was confirmed to be 1.64. That is, the difference Δn between the refractive index in the slow axis direction of the PEN film, which is the optically anisotropic layer, and the refractive index of the coPEN film, which is the optically isotropic layer, is 0.07.

Subsequently, a laminate obtained by coextrusion of PEN and coPEN was stretched and heat-treated to prepare a linearly polarized reflective film (also referred to as a "reflective film"). The thickness of this linearly polarized light reflective film is about 28 μm, and the linearly polarized light reflective layer (UV layer) having 44 layers of PEN and coPEN alternately having the film thickness shown in the column of UV layer in Table 1 below. A linearly polarized light reflecting layer (B layer) having 44 alternating layers of PEN and coPEN with the film thickness shown in the row of the B layer, and 39 alternating layers of PEN and coPEN with the film thickness shown in the row of the G layer. and a linearly polarized light reflecting layer (R layer) having 38 layers of PEN and coPEN alternately having the film thickness shown in the row of the R layer (R layer) in this order.

(Comparative example)
[Preparation of Coating Liquid for Forming Cholesteric Liquid Crystal Layer]
The coating solution for forming each cholesteric liquid crystal layer (UV layer, B layer, G layer, R layer) prepared in Example 1 was used as it was.

In Examples 1 to 5 and Comparative Examples, a UV layer, a B layer, a G layer, and an R layer (layers cured by a polymerization reaction) having a thickness of, for example, about 3 μm are formed on the temporary support, It was confirmed that each selective reflection layer, which is a reflective layer for right-handed circularly polarized light and whose selective reflection center wavelength is, for example, the wavelengths shown in Table 2 below, can be formed.

<Preparation of coating solution for forming retardation layer>
A retardation layer-forming coating liquid was prepared by mixing the following components so as to have the composition ratio shown below.
・Mixture 1 100 parts by mass ・Fluorine-based horizontal alignment agent 1 (alignment control agent 1) 0.05 mass parts ・Fluorine-based horizontal alignment agent 2 (alignment control agent 2) 0.01 mass parts ・Polymerization initiator IRGACURE OXE01 (product Name, manufactured by BASF) 1.0 parts by mass ・Solvent (methyl ethyl ketone) Amount that makes the solute concentration 20% by mass

<Preparation of Coating Liquid for Forming Polarization Conversion Layer>
A coating liquid for forming a polarization conversion layer was prepared by mixing the following components so as to have the composition ratio shown below.
・Mixture 1 100 parts by mass ・Fluorine-based horizontal alignment agent 1 (alignment control agent 1) 0.05 mass parts ・Fluorine-based horizontal alignment agent 2 (alignment control agent 2) 0.02 mass parts ・Right-rotating chiral agent Paliocolor LC756 (trade name, manufactured by BASF) 0.26 parts by mass ・Polymerization initiator IRGACURE OXE01 (trade name, manufactured by BASF) 1.0 parts by mass ・Solvent (methyl ethyl ketone) Amount that makes the solute concentration 20% by mass

Mixture 1:

  Orientation control agent 2:

A coating solution for forming a polarization conversion layer is prepared so that a cholesteric liquid crystal layer is formed by adjusting the prescription amount of the right-handed chiral agent LC756 in the coating solution composition described above so that the desired selective reflection center wavelength λ is obtained. bottom. The selective reflection central wavelength λ for light with an incident angle of 5° was measured by FTIR (Fourier Transform Infrared Spectroscopy, manufactured by PerkinElmer, trade name: It was determined by measurement of Spectrum Two).
In addition, in the cholesteric liquid crystal layer, the film thickness d of the helical structure is represented by "the pitch P of the helical structure.times.the number of pitches". The pitch P of the helical structure means the thickness of the layer when the helically aligned liquid crystal compound rotates 360°. In the cholesteric liquid crystal layer, the selective reflection central wavelength λ for light with an incident angle of 5° coincides with "the pitch P of the helical structure×the in-plane average refractive index n" (λ=P×n). Therefore, the pitch P of the helical structure is "selective reflection center wavelength λ for light with an incident angle of 5°/in-plane average refractive index n" (P = λ/n). For this reason, in the case of a cholesteric liquid crystal layer, the coating solution for forming the polarization conversion layer was prepared so that the selective reflection center wavelength λ for light with an incident angle of 5° was a desired wavelength. In the formation of the polarization conversion layer, which will be described later, this coating solution for forming the polarization conversion layer was applied so as to have a desired film thickness, the polarization conversion layer was formed, and the number of pitches was determined.
Table 3 shows combinations of the target pitch number of the polarization conversion layer, film thickness, and selective reflection center wavelength λ (center wavelength λ) for light with an incident angle of 5° for the prepared coating solution for forming the polarization conversion layer. show.

<Preparation of Saponified Cellulose Acylate Film>
In the preparation of the cellulose acylate film described in Example 20 of WO2014/112575, 2 parts by mass of the ultraviolet absorber described in paragraph [0277] of WO2014/112575 was used as the core layer cellulose acylate dope. Instead, a core layer cellulose acylate dope obtained by blending 3 parts by mass of an ultraviolet absorber UV-531 (trade name) manufactured by Teisei Kako Co., Ltd. with 100 parts by mass of cellulose acetate (not including ester oligomer A). A cellulose acylate film having a thickness of 40 μm was produced in the same manner as above, except that it was used.
The produced cellulose acylate film was passed through a dielectric heating roll at a temperature of 60°C to raise the film surface temperature to 40°C. After that, an alkaline solution having the composition shown below was applied to one side of the film using a bar coater so that the coating amount was 14 mL/m ² , and heated to 110 ° C. with a steam type far-infrared heater (manufactured by Noritake Co., Ltd.). ) for 10 seconds.
Then, using the same bar coater, pure water was applied so as to be 3 mL/m ² .
Subsequently, washing with water using a fountain coater and draining with an air knife were repeated three times, and then the film was dried by staying in a drying zone at 70°C for 5 seconds to prepare a saponified cellulose acylate film (transparent support).
The in-plane retardation of the saponified cellulose acylate film was measured with AxoScan (manufactured by Axometrics, trade name) and found to be 1 nm.

――――――――――――――――――――――――――――――――――
Composition of Alkaline Solution――――――――――――――――――――――――――――――――
・Potassium hydroxide 4.7 parts by mass ・Water 15.7 _{parts by mass ・Isopropanol 64.8 parts by mass ・Surfactant (C16H33O(CH2CH2O)10H ) 1.0 parts by} mass ・Propylene Glycol 14.9 parts by mass――――――――――――――――――――――――――――――――――

<Preparation of alignment film>
On the saponified surface of the saponified cellulose acylate film (transparent support), a coating solution for forming an alignment film having the composition shown below was applied with a wire bar coater so as to be 24 mL/m ² , and heated at 100°C. It was dried with air for 120 seconds to form an alignment film.

――――――――――――――――――――――――――――――――――
Composition of coating solution for forming alignment film――――――――――――――――――――――――――――――――――
- Modified polyvinyl alcohol shown below 28 parts by mass - Citric acid ester (trade name: AS3, manufactured by Sankyo Chemical Co., Ltd.) 1.2 parts by mass - Photoinitiator (trade name: Irgacure 2959, manufactured by BASF)
0.84 parts by mass Glutaraldehyde 2.8 parts by mass Water 699 parts by mass Methanol 226 parts by mass ――――――――――――――――――――――――――― ―――――――

  (denatured polyvinyl alcohol)

<Preparation of Laminate of Retardation Layer, Selective Reflection Layer, and Polarization Conversion Layer>
(Example 1)
A cellulose acylate film on which an orientation layer was formed was used as a support (transparent base).
The orientation film surface of the support was rubbed in a direction rotated clockwise by 45° with respect to the long side direction of the support. Specifically, rayon cloth was used, pressure: 0.1 kgf (0.98 N), number of revolutions: 1000 rpm (revolutions per minute), conveying speed: 10 m/min, number of reciprocations: 1.

The retardation layer-forming coating solution prepared above was applied to the rubbed surface of the alignment film on the support using a wire bar, and then dried.
Next, it is placed on a hot plate at 50° C. and irradiated with ultraviolet rays for 6 seconds by 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 to convert the liquid crystal phase. Fixed. As a result, a retardation layer having a thickness adjusted so as to provide a desired frontal retardation, that is, a desired retardation, was obtained.
When the retardation of the produced retardation layer was measured by AxoScan (manufactured by Axometrics, trade name), it was 126 nm.

The coating liquid for forming the cholesteric liquid crystal layer (UV layer) prepared above was applied to the surface of the obtained retardation layer using a wire bar at room temperature so that the thickness of the dry film after drying was 4.0 μm. to obtain a coating layer.
After drying the coating layer at room temperature for 30 seconds, it was heated in an atmosphere of 85° C. for 2 minutes. After that, in an environment with an oxygen concentration of 1000 ppm or less, ultraviolet light is irradiated at 60° C. for 6 to 12 seconds with a D bulb (60 mW/cm ² lamp) manufactured by Fusion Co., Ltd. at an output of 60% to fix the cholesteric liquid crystal phase. , a 4.0 μm thick cholesteric liquid crystal layer (UV layer) was obtained.
Subsequently, the same process was repeated using a coating solution for forming a cholesteric liquid crystal layer (B layer) on the surface of the obtained cholesteric liquid crystal layer (UV layer) to obtain a cholesteric liquid crystal layer (B layer) having a thickness of 4.1 μm. layer) were laminated.
Next, the same process was repeated using a coating liquid for forming a cholesteric liquid crystal layer (G layer) on the surface of the obtained cholesteric liquid crystal layer (B layer) to obtain a cholesteric liquid crystal layer (G layer) having a thickness of 3.9 μm. ) was laminated.
Next, on the surface of the obtained cholesteric liquid crystal layer (G layer), the same process was performed using the coating solution for forming the quantum dot-containing cholesteric liquid crystal layer (R layer) prepared in Example 1 above. A cholesteric liquid crystal layer (R layer) having a thickness of 4.1 μm was repeatedly laminated.
Thus, a selective reflection layer having four cholesteric liquid crystal layers on the retardation layer was obtained.

Next, on the surface of the obtained cholesteric liquid crystal layer (R layer), the coating solution for forming the polarization conversion layer shown in Table 3 is further applied so as to have the target film thickness shown in Table 3. formed a layer. Thus, a laminate was obtained in which the retardation layer, the selective reflection layer, and the polarization conversion layer were laminated in this order on the support.
In addition, in the description of the production of laminates according to Example 2, Examples 3 to 5, and Comparative Examples described later, the description of the same steps as in Example 1 will be omitted or simplified.

(Example 2)
[Preparation of fluorescent dye layer]
The quantum dot-containing polymerizable composition 1 prepared in Example 1 was applied to the surface of the obtained cholesteric liquid crystal layer (R layer) with a die coater to form a coating film having a thickness of 50 μm. Then, it was passed through a heating zone at 100° C. for 3 minutes, and cured by irradiating with ultraviolet rays using a 160 W/cm air-cooled metal halide lamp (manufactured by Eye Graphics Co., Ltd.). Thus, a fluorescent dye layer containing quantum dots was formed on the R layer. The dose of ultraviolet rays was 2000 mJ/cm ² .

Next, the coating solution for forming a polarization conversion layer shown in Table 3 was applied to the surface of the obtained fluorescent dye layer so as to have the target film thickness shown in Table 3, thereby forming a polarization conversion layer. . Thus, a laminate was obtained in which the retardation layer, the selective reflection layer, the fluorescent dye layer, and the polarization conversion layer were laminated in this order on the support.

(Example 3)
On the surface of the obtained cholesteric liquid crystal layer (B layer), in the same manner as in Example 2, using the quantum dot-containing polymerizable composition 1 prepared in Example 1, a fluorescent dye layer containing quantum dots was formed. . Next, a coating solution for forming a cholesteric liquid crystal layer (G layer) was used to laminate a cholesteric liquid crystal layer (G layer) on the surface of this fluorescent dye layer by repeating the same steps as in Example 1. The film thicknesses of the cholesteric liquid crystal layers (UV layer, B layer, G layer and R layer) according to Example 3 were 3.0 μm, 3.5 μm, 4.0 μm and 4.5 μm, respectively.

(Example 4)
For forming a quantum dot-containing cholesteric liquid crystal layer (R layer) containing two types of quantum dots having different emission peak wavelengths, prepared in Example 4 above, on the surface of the obtained cholesteric liquid crystal layer (G layer). Using the coating liquid, the same steps as in Example 1 were repeated to laminate a cholesteric liquid crystal layer (R layer). The film thicknesses of the cholesteric liquid crystal layers (UV layer, B layer, G layer, and R layer) according to Example 4 were 3.0 μm, 3.5 μm, 4.0 μm, and 4.5 μm, respectively.

(Example 5)
In the same manner as in Example 2, the quantum dot-containing polymerizable composition 1 prepared in Example 1 was used on the surface of the resulting linearly polarized light reflective layer (R layer) to form a fluorescent dye layer containing quantum dots. was formed on the R layer.

(Comparative example)
The same process as in Example 1 was performed on the surface of the obtained cholesteric liquid crystal layer (G layer) using the coating liquid for forming the cholesteric liquid crystal layer (R layer) containing no quantum dots, which was prepared in the above-described comparative example. A cholesteric liquid crystal layer (R layer) was repeatedly laminated.

Table 4 below is a table summarizing the selective reflection center wavelengths and fluorescent dyes of each layer according to Examples 1 to 5 and Comparative Example. In Examples 1 to 4 and Comparative Example, the selective reflection center wavelengths of the UV layer, B layer, G layer, and R layer at an incident angle of 5° are 445 nm, 526 nm, 608 nm, and 748 nm, respectively.

<Production of windshield glass>
(Examples 1 to 4 and Comparative Example)
A windshield glass having the laminate obtained above was produced as follows.

As the first sheet glass and the second sheet glass, curved glass (visible light transmittance of 90%) having a length of 1000 mm, a width of 1500 mm, and a thickness of 2 mm was prepared.
A 0.76 mm-thick PVB (polyvinyl butyral) film manufactured by Sekisui Chemical Co., Ltd. was prepared as an intermediate film.
Moreover, the heat seal layer was produced as follows.

[Preparation of heat seal layer]
A coating solution for forming a heat seal layer was prepared by mixing the following components.
・PVB sheet piece (manufactured by Sekisui Chemical Co., Ltd., S-lec film) 5.0 parts by mass ・Methanol 90.25 parts by mass ・Butanol 4.75 parts by mass

A heat seal layer forming coating liquid was applied to the laminate using a wire bar, dried, and heat-treated at 50°C for 1 minute to obtain a heat seal layer having a thickness of 1 µm.

The laminate, the first sheet glass, the second sheet glass, the intermediate film, and the heat seal layer are laminated so as to have the configuration shown in Table 5 below, and the laminate is heated at 90 ° C. and 10 kPa (0.1 atm). held for 1 hour. Then, it was heated in an autoclave (manufactured by Kurihara Seisakusho) at 115° C. and 1.3 MPa (13 atmospheres) for 20 minutes to remove air bubbles, thereby obtaining a windshield glass.

(Example 5)
The selective reflection layer (dielectric multilayer film) produced by the method described above was sandwiched between two intermediate films. This laminate is sandwiched between the first plate glass and the second plate glass so that the fluorescent dye layer containing the quantum dots in the dielectric multilayer film is on the first plate glass side. The structure shown in Table 5 below. and treated in the same manner as in Examples 1 to 4 to obtain windshield glass.
For the windshield glasses of Examples 1 to 5 and Comparative Example produced as described above, when installed in a vehicle, etc., the first plate glass is used on the outside of the vehicle, and the second plate glass is used on the inside of the vehicle. Then, the reflection spectrum was measured and the reflection color was evaluated as follows.

<Measurement of reflection spectrum of selective reflection layer>
A black PET (polyethylene terephthalate) film (light absorber) was attached to the rear surface of the second plate glass of the produced windshield glass.
Using a spectrophotometer (manufactured by JASCO Corporation, V-670), from the first plate glass side of the windshield glass, from the direction of the desired angle with respect to the normal direction of the windshield glass surface P polarized light or S polarized light were incident, and the reflection spectra of P-polarized light and S-polarized light in the wavelength band of 300 to 800 nm were measured. An average value (average reflection spectrum) of the measured P-polarized reflection spectrum and S-polarized reflection spectrum was obtained.
In the present invention, the selective reflection center wavelength (60°), reflectance (60°), and half width (60°) were measured by light incident at an angle of 60° with respect to the normal direction of the windshield glass surface. It is calculated based on the reflection spectrum, and the selective reflection central wavelength (5°) means a value calculated based on the reflection spectrum measured by light incident at an angle of 5° with respect to the normal direction of the windshield glass surface.

The average value of the reflectance when P-polarized light is incident and the reflectance when S-polarized light is incident is synonymous with the reflectance when unpolarized light (natural light) is incident. That is, the average value of the P-polarized reflection spectrum and the S-polarized reflection spectrum is synonymous with the reflection spectrum when natural light is incident.

From the calculated average values of the reflection spectra of P-polarized light and S-polarized light, each selective reflection center wavelength λ and its half width Δλ in the wavelength band of 400 nm or more and less than 500 nm, the wavelength band of 500 nm or more and less than 600 nm, and the wavelength band of 600 nm to 700 nm , were calculated by the method described above, based on the two wavelengths at which the maximum value of the natural light reflectance and the reflectance between the maximum maximum value and the minimum minimum value of the natural light reflectance were obtained. Further, the reflectance at each selective reflection center wavelength λ was the reflectance value at the selective reflection center wavelength λ in the calculated average value of the reflection spectra of P-polarized light and S-polarized light.

<Evaluation of reflected color>
Natural light is incident from the direction of 60° to the normal direction of the first plate glass from the first plate glass side, and a spectrophotometer (manufactured by JASCO Corporation, V-670) is measured from the normal direction of the first plate glass. was used to measure reflectance spectra. According to JIS (Japanese Industrial Standard) R3106, at wavelengths of 380 to 780 nm in increments of 10 nm, the reflectance is multiplied by a coefficient corresponding to the luminous efficiency and the emission spectrum of the D65 light source to calculate the reflectance, and the reflected color is calculated from the spectrum. Taste a* and b* were calculated.
Further, the same calculation was performed when the incident angle of natural light was changed to a direction of 5° with respect to the normal direction of the first plate glass.
Reflected color was evaluated by applying the following evaluation criteria. In Table 6 below, the evaluations described in the columns of 5° and 60° of the reflected color are obtained when natural light is incident from a direction of 5° or 60° with respect to the normal direction of the first plate glass, respectively. Equivalent to evaluation.

- Evaluation criteria (reflected color) -
AAA: |a*|≤2 and |b*|≤3, and looks very white when white is projected.
AA: |a*|≤3 and |b*|≤3 (excluding those corresponding to the above AAA), and looks white when white is projected.
・A: |a*|≤5 and |b*|≤5 (excluding those falling under the above AAA or above AA), and when white is projected, it looks very slightly reddish. .
・B: |a*|≤7 and |b*|≤7 (excluding those corresponding to the above AAA or the above AA or the above A), and when white is projected, there is a slight tint looks like

Table 6 shows the results. In this test, a rating of "AAA" or "AA" is a passing level.

In a windshield glass having a selective reflection layer and not containing a fluorescent dye (quantum dot) (comparative example), the reflected color at a light incident angle of 5° was at an acceptable level (evaluation of reflected color: "AA" ), the reflected color at a light incident angle of 60° appeared slightly reddish (evaluation of reflected color: “A”), and the appearance color was inferior in transparency depending on the viewing angle. On the other hand, the windshield glass (Examples 1 and 4) containing the fluorescent dye (quantum dot) having the above emission peak wavelength in the selective reflection layer and the fluorescent dye (quantum dot) containing the above emission peak wavelength In the case of the windshield glass having a layer (Examples 2, 3 and 5), the reflected color was not affected at both the light incident angles of 5° and 60° (evaluation of the reflected color " AAA” to “AA”), and compared to the comparative examples, the appearance color transparency was excellent at both the light incident angles of 5° and 60°.
From the above results, the effect of the present invention is clear.

Although the present invention has been described in detail above, the present invention is not limited to the above-described embodiments except as defined in the present invention, and various improvements and modifications can be made without departing from the gist of the present invention. can be added, and such forms are also included in the present invention.

While we have described our invention in conjunction with its embodiments, we do not intend to limit our invention in any detail to the description, unless otherwise specified, but in accordance with the spirit of the invention as set forth in the appended claims. We believe that it should be interpreted broadly without violating scope.

This application claims priority based on Japanese Patent Application No. 2021-181369 filed in Japan on November 5, 2021 and Japanese Patent Application No. 2022-023930 filed in Japan on February 18, 2022. , the contents of which are hereby incorporated by reference as part of the present description.

10 reflective films 10A, 10B linear polarized reflective film 11 selective reflection layer 12 cholesteric liquid crystal layer 12R cholesteric liquid crystal layer having selective reflection central wavelength _λR 12G cholesteric liquid crystal layer having selective reflection central wavelength _λG 12B selective reflection central wavelength _λB Cholesteric liquid crystal layer 13R First lamination part having selective reflection central wavelength _λR 13G Second lamination part having selective reflection central wavelength _{λG 13B} Third lamination part having selective reflection central wavelength λB 13Ra, 13Ga, 13Ba Optical differences Anisotropic layer 13Rb, 13Gb, 13Bb Optically isotropic layer 14 Polarization conversion layer 16 Retardation layer 18 Transparent substrate 20 Head-up display system (HUD system)
22 projectors 24, 24A, 24B windshield glass 28 second glass plate 30 first glass plate 36 intermediate film 38 adhesive layer (heat seal layer)
D Driver n _e1 Refractive index in the direction of the slow axis of the optically anisotropic layer n _o1 Refractive index in the direction perpendicular to the slow axis of the optically anisotropic layer n _o2 Refractive index of the optically isotropic layer Y Vertical direction

Claims (14)

The selective reflection center wavelength for light with an incident angle of 60° is a selective reflection layer (I) having the following (a), a selective reflection layer (II) having the following (b), and a selective reflection having the following (c). having at least a layer (III) and
A reflective film containing at least one fluorescent dye having an emission peak in the visible light region separated by 5 nm or more from any of the selective reflection center wavelengths of the selective reflection layers (I) to (III).
(a) 400 nm or more and less than 500 nm (b) 500 nm or more and less than 600 nm (c) 600 nm or more and 700 nm or less 2. The reflective film according to claim 1, comprising a layer (FL) containing said fluorescent dye and not functioning as a selective reflection layer. The reflective film according to claim 2, wherein the layer (FL) is not arranged between two selective reflection layers. The selective reflection layer (III) contains the fluorescent dye, or
A selective reflection layer other than the selective reflection layer (III) is arranged on one side of the selective reflection layer (III), and a layer (FL ), the reflective film of claim 1 . The reflective film according to any one of claims 1 to 4, wherein the emission peak wavelength of at least one of the fluorescent dyes is in the range of 450 nm or more and less than 550 nm. 6. The reflective film according to claim 5, comprising two or more of the fluorescent dyes, and at least one of the fluorescent dyes having an emission peak wavelength outside the range of 450 nm or more and less than 550 nm. 6. The reflective film according to claim 5, comprising two or more types of said fluorescent dyes, wherein at least one type of fluorescent dye has an emission peak wavelength in the range of 550 nm or more and 650 nm or less. Claims 1 to 7, wherein the selective reflection layers (I) to (III) each have a selective reflection central wavelength half width of 100 nm or less, and a natural light reflectance at the selective reflection central wavelength of 25% or more. The reflective film according to any one of . The reflective film according to any one of claims 1 to 8, comprising at least one polarization conversion layer. The reflective film according to any one of claims 1 to 9, wherein the selective reflection layers (I) to (III) are made of cholesteric liquid crystal. The reflective film according to any one of claims 1 to 9, wherein the selective reflection layers (I) to (III) are formed by laminating an optically anisotropic layer and an optically isotropic layer. A windshield having a first glass plate, a second glass plate, and the reflective film according to any one of claims 1 to 11 disposed between the first glass plate and the second glass plate. glass. a windshield glass according to claim 12;
A head-up display system comprising: a projector that irradiates the windshield glass with p-polarized projection image light. A transport equipped with a head-up display system according to claim 13.

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