JP6815491B2 - Transparent screen and video projection system - Google Patents

Description

The present invention relates to a transparent screen and an image projection system.

The layer formed by fixing the cholesteric liquid crystal phase is known as a layer having a property of selectively reflecting either right-handed circularly polarized light or left-handed circularly polarized light in a specific wavelength range. Therefore, it has been developed into various uses, and as an example, various uses as a screen for projection have been proposed.

A projection screen or other projection screen using a layer in which the cholesteric liquid crystal phase is fixed is required to have an enlarged viewing angle.
More specifically, when light is incident from the normal direction of the surface of the layer formed by fixing the cholesteric liquid crystal phase, either right circularly polarized light or left circularly polarized light is selectively reflected. .. At that time, if the reflection is performed not only in the normal direction but also in the oblique direction, the visibility from the oblique direction is improved. That is, when used for a screen or the like in which a layer formed by fixing a cholesteric liquid crystal phase is used as a cholesteric liquid crystal layer, the cholesteric liquid crystal layer has a characteristic of reflecting incident light in various directions (so-called diffuse reflectance). It is required to be excellent.
Further, when the layer formed by fixing the cholesteric liquid crystal phase is applied to a transparent screen or the like, it is also required to have high transparency, that is, low haze.

For example, Patent Document 1 includes a polarization-selective cholesteric liquid crystal layer that diffusely reflects a specific polarization component as a reflection-type projection screen, and the polarization-selection cholesteric liquid crystal layers are at least two or more partially selected cholesteric liquid crystals laminated with each other. The first partial selection cholesteric liquid crystal layer having a layer and having a wavelength range showing a color most easily absorbed by the polarization selection cholesteric liquid crystal layer among the partial selection cholesteric liquid crystal layers is diffusely reflected on the outermost surface of the observation side. The projection screen placed in is described.
In the projection screen described in Patent Document 1, the partially selected cholesteric liquid crystal layer has a cholesteric liquid crystal structure (a layer formed by fixing the cholesteric liquid crystal phase), and due to the structural non-uniformity (defect) of the cholesteric liquid crystal structure. , Diffuses and reflects light of a specific polarization component.

Further, in Patent Document 2, a transparent resin layer provided on one surface of the first transparent base material and having a plurality of convex portions on the surface, and a specific wavelength provided on the surface of the convex portions and incident are defined. A selective cholesteric liquid crystal layer having a cholesteric liquid crystal structure that selectively reflects right-handed or left-circularly polarized laser light, and a transparent coating layer that covers the surface of the selective cholesteric liquid crystal layer are provided, and the surface of the transparent coating layer is provided. A reflective screen is described that is flat and has the same or nearly the same refractive index of the first transparent substrate, the refractive index of the transparent resin layer, and the refractive index of the transparent coating layer.
In the reflective screen described in Patent Document 2, light is diffused by forming a selective cholesteric liquid crystal layer having a cholesteric liquid crystal structure on the surface of the convex portion. Further, it is said that transparency can be obtained by forming the surface of the transparent coating layer flat and making the refractive index of each layer the same.

Japanese Unexamined Patent Publication No. 2005-107508 Japanese Unexamined Patent Publication No. 2014-071250

However, for example, in the case of the projection screen described in Patent Document 1, since the diffuse reflectability is obtained by introducing a defect into the cholesteric liquid crystal structure, the diffuse reflectivity and transparency do not meet the recent demand levels. For example, a transparent screen using a layer formed by fixing a conventional cholesteric liquid crystal phase is required to have further improvement in diffuse reflectance and transparency.

An object of the present invention is to solve such a problem of the prior art, and to provide a transparent screen and an image projection system having good diffuse reflectance, low haze, and excellent transparency. It is in.

As a result of diligent studies on the problems of the prior art, the present inventors have a support and a plurality of cholesteric liquid crystal layers having a plurality of cholesteric liquid crystal phases laminated on the support and having a plurality of cholesteric liquid crystal phases fixed thereto. At least one of the liquid crystal layers is a wavy cholesteric liquid crystal layer having a wavy structure in the bright and dark parts derived from the cholesteric liquid crystal phase in the cross section, and at least one other layer among the plurality of cholesteric liquid crystal layers is It has been found that the above problems can be solved by forming a flat cholesteric liquid crystal layer having a flat structure in which the bright and dark parts derived from the cholesteric liquid crystal phase are parallel to the main surface of the support in the cross section.
That is, it was found that the above object can be achieved by the following configuration.

[1] Support and
It has a plurality of cholesteric liquid crystal layers which are laminated on the support and which are formed by fixing the cholesteric liquid crystal phase.
Of the plurality of cholesteric liquid crystal layers, at least one layer is a corrugated cholesteric liquid crystal layer having a wavy structure in bright and dark areas derived from the cholesteric liquid crystal phase in cross section.
Of the plurality of cholesteric liquid crystal layers, at least one other layer is a transparent cholesteric liquid crystal layer having a flat structure in which bright and dark portions derived from the cholesteric liquid crystal phase are parallel to the main surface of the support in cross section. screen.
[2] The transparent screen according to [1], wherein the selective reflection wavelength of at least one layer of the corrugated cholesteric liquid crystal layer is the same as the selective reflection wavelength of at least one layer of the flat cholesteric liquid crystal layer.
[3] Two or more corrugated cholesteric liquid crystal layers having different selective reflection wavelengths and
The transparent screen according to [1] or [2], which has two or more flat cholesteric liquid crystal layers having the same selective reflection wavelength as the selective reflection wavelength of each corrugated cholesteric liquid crystal layer.
[4] The transparent screen according to any one of [1] to [3], wherein the turning direction of the circularly polarized light reflected by the plurality of cholesteric liquid crystal layers is the same for all the cholesteric liquid crystal layers.
[5] It has two or more flat cholesteric liquid crystal layers having the same selective reflection wavelength and the same turning direction of reflected circularly polarized light.
The transparent screen according to any one of [1] to [4], which has a λ / 2 plate arranged between two or more flat cholesteric liquid crystal layers.
[6] It has two or more corrugated cholesteric liquid crystal layers having the same selective reflection wavelength and the same turning direction of reflected circularly polarized light.
The transparent screen according to any one of [1] to [5], which has a λ / 2 plate arranged between two or more corrugated cholesteric liquid crystal layers.
[7] The transparent screen according to any one of [1] to [3], which has two or more flat cholesteric liquid crystal layers having the same selective reflection wavelength but different turning directions of reflected circularly polarized light.
[8] The transparent screen according to any one of [1] to [3] and [7], which has two or more corrugated cholesteric liquid crystal layers having the same selective reflection wavelength but different turning directions of reflected circularly polarized light.
[9] The transparent screen according to any one of [1] to [8], wherein the total light transmittance of the support is 80% or more.
[10] The transparent screen according to any one of [1] to [9], wherein the formation surface of the cholesteric liquid crystal layer of the support is a flat surface.
[11] The transparent screen according to any one of [1] to [10], wherein the total light transmittance of the transparent screen is 50% or more.
[12] The transparent screen according to any one of [1] to [11] and
An image projection system having a laser projector that irradiates a transparent screen with light.
[13] The image projection system according to [12], wherein the selective reflection wavelength of at least one cholesteric liquid crystal layer included in the transparent screen is in the range of ± 20 nm of the center wavelength of the light source of the laser projector.
[14] The image projection system according to [12] or [13], wherein the light emitted by the laser projector is circularly polarized light.
[15] The image projection system according to [14], wherein the turning direction of the circular polarization reflected by at least one of the cholesteric liquid crystal layers of the transparent screen coincides with the turning direction of the circular polarization irradiated by the laser projector.

According to the present invention, it is possible to provide a transparent screen and an image projection system having good diffuse reflectance, low haze, and excellent transparency.

It is sectional drawing which shows an example of the transparent screen of this invention conceptually. It is a conceptual diagram for demonstrating the flat structure of a flat cholesteric liquid crystal layer. It is a conceptual diagram for demonstrating the wavy structure of a corrugated cholesteric liquid crystal layer. It is a figure which conceptually shows an example of the image projection system of this invention. It is sectional drawing which conceptually shows another example of the transparent screen of this invention. It is sectional drawing which conceptually shows another example of the transparent screen of this invention. It is sectional drawing which conceptually shows another example of the transparent screen of this invention. It is sectional drawing which conceptually shows another example of the transparent screen of this invention. It is a conceptual diagram for demonstrating the evaluation method in an Example.

Hereinafter, the present invention will be described in detail. The numerical range represented by using "~" in the present specification means a range including the numerical values before and after "~" as the lower limit value and the upper limit value.
Further, in the present specification, "orthogonal" and "parallel" include a range of errors allowed in the technical field to which the present invention belongs. For example, "orthogonal" and "parallel" mean that the error is within ± 10 ° with respect to strict orthogonality or parallelism, and the error with respect to strict orthogonality or parallelism is 5 ° or less. It is preferably 3 ° or less, and more preferably 3 ° or less.
In addition, angles other than "orthogonal" and "parallel", for example, specific angles such as 15 ° and 45 °, shall also include a range of errors allowed in the technical field to which the present invention belongs. For example, in the present invention, the angle means that it is less than ± 5 ° with respect to the concretely indicated exact angle, and the error with respect to the indicated exact angle is ± 3 ° or less. It is preferably present, and preferably ± 1 ° or less.

Further, in the present specification, "(meth) acrylate" is a notation representing both acrylate and methacrylate, and "(meth) acryloyl group" is a notation representing both an acryloyl group and a methacryloyl group. "(Meta) acrylic" is a notation that represents both acrylic and methacrylic.
As used herein, "identical" shall include an error range generally tolerated in the art. Further, in the present specification, when the term "all", "all" or "whole surface" is used, it includes not only the case of 100% but also the error range generally accepted in the technical field, for example, 99% or more. It shall include the case where it is 95% or more, or 90% or more.

In the present specification, visible light is light having a wavelength visible to the human eye among electromagnetic waves, and indicates light in a wavelength range of more than 400 nm and less than 700 nm. Invisible light is light in a wavelength range of 400 nm or less or 700 nm or more. Further, although not limited to this, among visible light, light in the wavelength range of 420 nm or more and less than 500 nm is blue light (B light), and light in the wavelength range of 500 nm or more and less than 600 nm is green light (G light). Yes, the light in the wavelength range of 600 nm or more and less than 700 nm is red light (R light). Further, although not limited to this, among the invisible light, the light in the wavelength range of 200 to 400 nm is ultraviolet light, and the light in the wavelength range of 700 to 1000 nm is infrared light.

In the present specification, the selective reflection wavelength is a half-value transmittance expressed by the following formula: T1 / 2 (%), where Tmin (%) is the minimum value of the transmittance of the target object (member). It refers to the average value of the two wavelengths indicating.
Formula for calculating half-value transmittance: T1 / 2 = 100- (100-Tmin) / 2

In the present specification, "haze" means a value measured using a haze meter NDH-4000 manufactured by Nippon Denshoku Industries Co., Ltd.
In theory, haze means a value expressed by the following equation.
(Scattering transmittance of natural light from 380 to 780 nm) / (Scattering transmittance of natural light from 380 to 780 nm + direct transmittance of natural light) x 100%
The scattering transmittance is a value that can be calculated by subtracting the direct transmittance from the obtained omnidirectional transmittance using a spectrophotometer and an integrating sphere unit. The direct transmittance is the transmittance at 0 ° based on the value measured using the integrating sphere unit. That is, a low haze means that the amount of directly transmitted light is larger than the total amount of transmitted light.
In the present specification, the refractive index is the refractive index for light having a wavelength of 589.3 nm.

In the present specification, Re (λ) and Rth (λ) represent in-plane retardation at wavelength λ and retardation in the thickness direction, respectively. Unless otherwise specified, the wavelength λ is 550 nm.
In the present specification, Re (λ) and Rth (λ) are values measured at a wavelength λ with an AXoScan mular matrix polarimeter (manufactured by AXOMETRICS). By inputting the average refractive index ((Nx + Ny + Nz) / 3) and film thickness (d (μm)) in AxoScan,
Slow phase axial direction (°)
Re (λ) = R0 (λ)
Rth (λ) = ((Nx + Ny) /2-Nz) × d
Is calculated.
Although R0 (λ) is displayed as a numerical value calculated by AxoScan, it means Re (λ).

In the present specification, the refractive indexes Nx, Ny, and Nz are measured by using an Abbe refractometer (NAR-4T, manufactured by Atago Co., Ltd.) and using a sodium lamp (λ = 589 nm) as a light source. Further, when measuring the wavelength dependence, it can be measured with a multi-wavelength Abbe refractometer DR-M2 (manufactured by Atago Co., Ltd.) in combination with an interference filter.
In addition, the values in the Polymer Handbook (JOHN WILEY & SONS, INC) and the catalogs of various optical films can also be used. The values of the average refractive index of the main optical films are illustrated below: cellulose acylate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethylmethacrylate (1.49), It is polystyrene (1.59).

The transparent screen of the present invention
With the support
It has a plurality of cholesteric liquid crystal layers which are laminated on the support and which are formed by fixing the cholesteric liquid crystal phase.
Of the plurality of cholesteric liquid crystal layers, at least one layer is a corrugated cholesteric liquid crystal layer having a wavy structure in bright and dark areas derived from the cholesteric liquid crystal phase in cross section.
Of the plurality of cholesteric liquid crystal layers, at least one other layer is a transparent cholesteric liquid crystal layer having a flat structure in which bright and dark portions derived from the cholesteric liquid crystal phase are parallel to the main surface of the support in cross section. It is a screen.

An example of a preferred embodiment of the transparent screen of the present invention will be described below with reference to the drawings.
FIG. 1 shows a schematic cross-sectional view of an example of the transparent screen of the present invention.
The figures in the present specification are schematic views, and the thickness relationship and positional relationship of each layer do not always match the actual ones. The same applies to the following figure.

As shown in FIG. 1, the transparent screen 10a has a support 12, a flat cholesteric liquid crystal layer 16Rr formed on one main surface of the support 12, and a wave formed on the flat cholesteric liquid crystal layer 16Rr. It has a mold cholesteric liquid crystal layer 14Rr.

The flat cholesteric liquid crystal layer 16Rr and the corrugated cholesteric liquid crystal layer 14Rr are both layers in which the cholesteric liquid crystal phase is fixed.
In the following description, when it is not necessary to distinguish between the flat cholesteric liquid crystal layer and the corrugated cholesteric liquid crystal layer, these are collectively referred to as "cholesteric liquid crystal layer".
As is well known, the layer formed by fixing a cholesteric liquid crystal has wavelength selectivity for reflection, reflects only right-handed polarized light or only left-handed polarized light in a predetermined wavelength region, and transmits other light. ..

In the example shown in FIG. 1, the flat cholesteric liquid crystal layer 16Rr has a selective reflection wavelength in a region of red light (for example, 650 nm) and reflects right circularly polarized light of this wavelength. Further, the corrugated cholesteric liquid crystal layer 14Rr has a selective reflection wavelength in a region of red light (for example, 650 nm) and reflects right circularly polarized light of this wavelength. That is, the flat cholesteric liquid crystal layer 16Rr and the corrugated cholesteric liquid crystal layer 14Rr have the same selective reflection wavelength and the same turning direction of the reflected circularly polarized light. Further, the cholesteric liquid crystal layer transmits light in a wavelength range other than the selective reflection wavelength and circularly polarized light having a reverse turning direction. Therefore, the cholesteric liquid crystal layer has transparency.
In the present specification, the same selective reflection wavelength of the cholesteric liquid crystal layer means that the difference in the selective reflection wavelength of each cholesteric liquid crystal layer is 20 nm or less.

As will be described later, the cholesteric liquid crystal layer of the transparent screen of the present invention is not limited to having a selective reflection wavelength in the red light region, and the selective reflection wavelength is set in the green light region (for example, 550 nm). It may have, or it may have a selective reflection wavelength in the region of blue light (for example, 450 nm). Alternatively, another wavelength region (infrared region, ultraviolet region, etc.) may be used as the selective reflection wavelength.
Further, the cholesteric liquid crystal layer of the transparent screen of the present invention is not limited to one that reflects right circularly polarized light, and may be one that reflects left circularly polarized light.
Further, in the following description, when it is not necessary to distinguish the flat cholesteric liquid crystal layers having different selective reflection wavelengths or the turning directions of the reflected circularly polarized light, these are collectively referred to as "flat cholesteric liquid crystal layer 16". Similarly, when it is not necessary to distinguish the corrugated cholesteric liquid crystal layers having different selective reflection wavelengths or the turning directions of the reflected circularly polarized light, these are collectively referred to as "corrugated cholesteric liquid crystal layer 14".

Here, FIG. 2 conceptually shows a cross section of the flat cholesteric liquid crystal layer 16. FIG. 2 is a diagram conceptually showing, for example, a state in which a cross section of a flat cholesteric liquid crystal layer 16 is observed with a scanning electron microscope (SEM).
As described above, the flat cholesteric liquid crystal layer 16 is a layer formed by fixing the cholesteric liquid crystal phase. In the cross section of the layer on which the cholesteric liquid crystal phase is fixed arranged on the support, a striped pattern of bright and dark areas is usually observed. Therefore, as shown in FIG. 2, in the cross section of the flat cholesteric liquid crystal layer 16, the bright part B and the dark part D are alternately arranged in the thickness direction (vertical direction in FIG. 2) due to the cholesteric liquid crystal phase. A laminated striped pattern is observed.
One bright portion B in FIG. 2 and two dark portions D arranged above and below the one bright portion B correspond to a spiral 1/2 pitch of the cholesteric liquid crystal phase.

As shown in FIG. 2, the bright portion B and the dark portion D in the cross section of the flat cholesteric liquid crystal layer 16 have a flat structure substantially parallel to the main surface of the support 12.
Generally, the striped pattern (layered structure) of the bright portion B and the dark portion D is formed so as to be parallel to the surface of the support 12 which is a flat surface, as shown in FIG.
That is, in the present invention, the flat cholesteric liquid crystal layer 16 is a layer having a cholesteric liquid crystal structure and having a structure in which the angle formed by the spiral shaft and the surface of the support 12 is constant. Specifically, the flat cholesteric liquid crystal layer 16 gives a striped pattern of bright and dark parts in the cross-sectional view of the flat cholesteric liquid crystal layer 16 observed by a scanning electron microscope, and at any 10 points, the dark part. The angle between the normal of the line formed by the glass and the surface of the support 12 satisfies 90 ° ± 5 °.

The flat cholesteric liquid crystal layer 16 in which such a cholesteric liquid crystal phase is fixed in a flat structure exhibits specular reflectivity. That is, when light is incident from the normal direction of the flat cholesteric liquid crystal layer 16 in which the cholesteric liquid crystal phase is fixed in a flat structure, the light is reflected in the normal direction, but the light is not easily reflected in the oblique direction. Also, the haze is low and the transparency is high.

FIG. 3 conceptually shows a cross section of the corrugated cholesteric liquid crystal layer 14. FIG. 3 is a diagram conceptually showing, for example, a state in which a cross section of a corrugated cholesteric liquid crystal layer 14 is observed with a scanning electron microscope (SEM).
As described above, the corrugated cholesteric liquid crystal layer 14 is a layer formed by fixing the cholesteric liquid crystal phase. In the cross section of the layer on which the cholesteric liquid crystal phase is fixed arranged on the support, a striped pattern of bright and dark areas is usually observed. Therefore, as shown in FIG. 3, in the cross section of the corrugated cholesteric liquid crystal layer 14, the bright portion B and the dark portion D are alternately arranged in the thickness direction (vertical direction in FIG. 3) due to the cholesteric liquid crystal phase. A laminated striped pattern is observed.
One bright portion B in FIG. 3 and two dark portions D arranged above and below the one bright portion B correspond to a spiral 1/2 pitch of the cholesteric liquid crystal phase.

As shown in FIG. 3, the bright portion B and the dark portion D in the cross section of the corrugated cholesteric liquid crystal layer 14 have a periodic wavy structure (undulation structure).
That is, in the present invention, the corrugated cholesteric liquid crystal layer 14 is a layer having a cholesteric liquid crystal structure and having a structure in which the angle formed by the spiral axis and the surface of the corrugated cholesteric liquid crystal layer 14 changes periodically. In other words, the corrugated cholesteric liquid crystal layer 14 has a cholesteric liquid crystal structure, and the cholesteric liquid crystal structure gives a striped pattern of bright and dark parts in a cross-sectional view of the cholesteric liquid crystal layer observed by a scanning electron microscope, and the dark part. It has a structure in which the normal of the line formed by the beam and the angle formed by the surface of the wavy cholesteric liquid crystal layer 14 change periodically.

The corrugated cholesteric liquid crystal layer 14 formed by fixing such a cholesteric liquid crystal phase with a wavy structure exhibits diffuse reflectance.
When the bright portion B and the dark portion D of the cholesteric liquid crystal layer have a wavy structure (undulation structure), when light is incident on the layer having the wavy structure (concavo-convex structure) from the normal direction of the layer, As shown in FIG. 3, since there is a region where the spiral axis of the liquid crystal compound is inclined, a part of the incident light is reflected in the oblique direction.
That is, in the corrugated cholesteric liquid crystal layer in which the cholesteric liquid crystal phase is fixed by a wavy structure, the layer having high diffuse reflection property can be realized by having the bright portion B and the dark portion D having a wavy structure. Further, the diffuse reflectance becomes better as the unevenness of the wavy structure between the bright portion B and the dark portion D becomes larger.

As will be described later, in the corrugated cholesteric liquid crystal layer having a wavy structure, for example, a composition containing a liquid crystal compound and a chiral agent is applied to a surface to be formed, and the composition is heated to turn the liquid crystal compound into a cholesteric liquid crystal phase. It can be formed by orienting, and then cooling the composition to fix the cholesteric liquid crystal phase by irradiation with ultraviolet rays or the like.
The diffuse reflectance of the corrugated cholesteric liquid crystal layer increases as the unevenness of the corrugated structure increases.
However, in order to make the wavy structure of the corrugated cholesteric liquid crystal layer into a wavy structure having sufficiently large irregularities to obtain high diffuse reflectance, the corrugated cholesteric liquid crystal layer is made to have a certain thickness or more. There is a need to.
When the corrugated cholesteric liquid crystal layer is thickened, the light transmittance is naturally lowered and the transparency of the transparent screen is lowered. That is, there is a trade-off relationship between the high light diffusivity due to the size of the unevenness of the wavy structure of the corrugated cholesteric liquid crystal layer and the transparency of the corrugated cholesteric liquid crystal layer.

Further, in the wavy structure in the cross section of the corrugated cholesteric liquid crystal layer, the pitch of the waves is substantially uniform, but the height of the waves may fluctuate.
For example, the height of the wave may be the highest in the central region in the thickness direction of the corrugated cholesteric liquid crystal layer, and gradually decrease toward the upper side (surface side) in the thickness direction and the support 12 side. .. That is, the amplitude of the wavy structure in the cross section of the corrugated cholesteric liquid crystal layer may be the largest in the central region in the thickness direction, and may be gradually decreased toward the surface side and the support 12 side.
Alternatively, a structure having waves having a uniform height over the entire thickness direction may be used, as in the wavy structure shown in FIG.

Further, the surface of each corrugated cholesteric liquid crystal layer (the interface with the cholesteric liquid crystal layer of the upper layer or air) may be flat or may have an uneven structure.
When the upper surface of the corrugated cholesteric liquid crystal layer has a concavo-convex structure, the concavo-convex structure is generally periodic (substantially periodic).
In the production method of the present invention described later, the corrugated cholesteric liquid crystal layer having such an uneven structure on the upper surface is at least selected for the chiral agent and / or the orientation control agent and the conditions for the heat treatment or the cooling treatment. It can be formed by doing one of them.

The corrugated cholesteric liquid crystal layer having an uneven surface has a wave height of a wavy structure in the cross section of the corrugated cholesteric liquid crystal layer, which is larger than that of the corrugated cholesteric liquid crystal layer having a flat surface.
Therefore, the corrugated cholesteric liquid crystal layer having irregularities on the surface can obtain higher diffuse reflectance. On the other hand, from the viewpoint of transparency, a corrugated cholesteric liquid crystal layer having a flat surface is preferable.

Further, the wavy structure (the wavy structure of the bright part and the dark part) in the cross section of the corrugated cholesteric liquid crystal layer has the same wavy structure not only in the horizontal direction of FIG. 1 but also in the cross section in the direction perpendicular to the paper surface of FIG. Is formed. That is, the wavy structure of the corrugated cholesteric liquid crystal layer is two-dimensionally formed in the plane direction of the cholesteric liquid crystal layer, and the corrugated cholesteric liquid crystal layer has a wavy structure in all directions.
However, the present invention is not limited to this, and the corrugated cholesteric liquid crystal layer may have a wavy structure in which continuous waves are formed so as to travel in only one direction in a cross section. However, in terms of diffuse reflectance, it is preferable that the corrugated cholesteric liquid crystal layer has a wavy structure in all directions as described above.

Further, the pitch of the wavy structure (distance between the tops of the waves) in the bright and dark parts of the cross section of the corrugated cholesteric liquid crystal layer is not particularly limited. The pitch of the wavy structure of the corrugated cholesteric liquid crystal layer is preferably 0.5 to 5 μm, more preferably 1 to 4 μm.
In order for the corrugated cholesteric liquid crystal layer to exhibit suitable diffuse reflectance, it is preferable to reduce the pitch (period) of the wavy structure and increase the wave height (height of unevenness, that is, amplitude). As for the pitch of the wavy structure and the height of the unevenness, the height of the unevenness usually tends to increase as the pitch increases. However, if the uneven structure is made too large, the diffusion of light in a direction unnecessary for the screen will increase, and the visibility from the front of the screen will deteriorate.

As described above, as a configuration for increasing diffusivity in a transparent screen that reflects specific light by a cholesteric liquid crystal layer, a configuration for introducing defects into the cholesteric liquid crystal structure and a plurality of protrusions are provided on the surface of the base material. A configuration has been proposed in which a cholesteric liquid crystal layer is formed on the convex portion. However, when the diffusivity is improved by these structures, the haze becomes high and the transparency becomes low.

On the other hand, the transparent screen of the present invention has a flat cholesteric liquid crystal layer having low haze and high transparency and a corrugated cholesteric liquid crystal layer having high diffuse reflection, so that both transparency and diffusivity are compatible. be able to. That is, for example, when it is used as a screen for projection, it is possible to display an image with a wide viewing angle while maintaining high transparency.

Here, as described above, in the example shown in FIG. 1, the flat cholesteric liquid crystal layer 16Rr and the corrugated cholesteric liquid crystal layer 14Rr are regions of red light having the same selective reflection wavelength.
By having the flat cholesteric liquid crystal layer 16 and the corrugated cholesteric liquid crystal layer 14 having the same selective reflection wavelength, both transparency and diffusivity are achieved for light in a wavelength range substantially the same as the selective reflection wavelength. can do.

Further, in the example shown in FIG. 1, the flat cholesteric liquid crystal layer 16Rr and the corrugated cholesteric liquid crystal layer 14Rr are right-handed circularly polarized light having the same turning direction of the reflected circularly polarized light.
By having the flat cholesteric liquid crystal layer 16 and the corrugated cholesteric liquid crystal layer 14 having the same turning direction of the reflected circularly polarized light, the reflectance of the circularly polarized light in the turning direction is enhanced, and the circle in the other turning direction is provided. Polarized light can be transmitted to increase transparency.

Further, in the image projection system of the present invention in which the transparent screen of the present invention is combined with a projector that irradiates the transparent screen with light (projects an image), it is preferable to use a laser projector as the projector. Since laser light has a narrow spectral line width, by combining a laser projector and a transparent screen having a cholesteric liquid crystal layer having wavelength selectivity for reflection, the light emitted by the laser projector can be suitably reflected. The amount of light passing through to the back surface side can be reduced. As a result, the brightness of the image projected on the transparent screen can be increased, and a clearer image can be obtained. At that time, it is preferable that the difference between the center wavelength of the light source of the laser projector and the selective reflection wavelength of the cholesteric liquid crystal layer is ± 20 nm or less.

Further, by making the light emitted by the laser projector circularly polarized light and making the turning direction the same as the turning direction of the circularly polarized light reflected by the cholesteric liquid crystal layer, the light emitted by the laser projector can be more preferably reflected. , The amount of light passing through to the back surface side can be reduced.

For example, in an image projection system having a transparent screen 10a and a laser projector 102 that irradiates the transparent screen 10a with light, such as the image projection system 100 shown in FIG. 4, the center wavelength of the light source of the laser projector 102 and the transparent screen. The difference from the selective reflection wavelength of the cholesteric liquid crystal layer (flat cholesteric liquid crystal layer 16Rr and corrugated cholesteric liquid crystal layer 14Rr) of 10a is set to ± 20 nm or less, and the cholesteric liquid crystal layer reflects the light emitted by the laser projector 102. The right circular polarization is used in the same turning direction as the turning direction of the circular polarization. As a result, almost all of the light emitted by the laser projector 102 can be reflected by the cholesteric liquid crystal layer (solid line in FIG. 4), and the amount of light passing to the back surface side of the transparent screen 10a can be reduced (FIG. 4). Middle dashed line). On the other hand, since the transparent screen 10a has high transparency, the observer A can visually recognize the scene on the back surface side of the transparent screen 10a (dashed line in FIG. 4).

Here, in the example shown in FIG. 1, the transparent screen 10a has one layer each of a flat cholesteric liquid crystal layer and a corrugated cholesteric liquid crystal layer, but the present invention is not limited to this, and the flat cholesteric liquid crystal layer and the wave It may be configured to have two or more mold cholesteric liquid crystal layers.

FIG. 5 shows a schematic cross-sectional view of another example of the transparent screen of the present invention.
The transparent screen 10b shown in FIG. 5 has a support 12, a flat cholesteric liquid crystal layer 16Br having a selective reflection wavelength in the blue light region and reflecting right circular polarization, and a selective reflection wavelength in the green light region. A flat cholesteric liquid crystal layer 16Gr that reflects right circular polarization, a flat cholesteric liquid crystal layer 16Rr that has a selective reflection wavelength in the red light region and reflects right circular polarization, and a selective reflection wavelength in the blue light region. The wave-shaped cholesteric liquid crystal layer 14Br having a right circular polarization and reflecting the right circular polarization, and the corrugated cholesteric liquid crystal layer 14Gr having a selective reflection wavelength in the green light region and reflecting the right circular polarization, and the red light region selected. It has a corrugated cholesteric liquid crystal layer 14Rr having a reflection wavelength and reflecting right circular polarization.
That is, the transparent screen 10b has a three-layer flat cholesteric liquid crystal layer 16 and a three-layer corrugated cholesteric liquid crystal layer 14. Further, the three-layer flat cholesteric liquid crystal layer 16 has different selective reflection wavelengths. Similarly, the three-layer corrugated cholesteric liquid crystal layer 14 has different selective reflection wavelengths from each other, and the three-layer corrugated cholesteric liquid crystal layer 14 has a selective reflection wavelength of any of the three-layer flat cholesteric liquid crystal layers 16. It is the same as the selective reflection wavelength.

In this way, by having two or more flat cholesteric liquid crystal layers 16 having different selective reflection wavelengths and a corrugated shape, it is possible to reflect light of a plurality of wavelengths, and the image projected on the transparent screen is displayed in color. can do.
Further, by having a structure having a flat cholesteric liquid crystal layer 16 and a corrugated cholesteric liquid crystal layer 14 for each selective reflection wavelength, transparency and diffusivity are provided for light in a wavelength range substantially the same as each selective reflection wavelength. Can be compatible with each other.

Further, the laser projector to be combined with the transparent screen 10b shown in FIG. 5 includes a red light source having red light as a central wavelength, a green light source having green light as a central wavelength, and a blue light source having blue light as a central wavelength. Is preferable. Further, it is preferable that the difference between the center wavelength of the red light source and the selective reflection wavelength of the flat cholesteric liquid crystal layer 16Rr and the corrugated cholesteric liquid crystal layer 14Rr is ± 20 nm or less. Similarly, the difference between the center wavelength of the green light source and the selective reflection wavelength of the flat cholesteric liquid crystal layer 16 Gr and the corrugated cholesteric liquid crystal layer 14 Gr is preferably ± 20 nm or less. Similarly, the difference between the center wavelength of the blue light source and the selective reflection wavelengths of the flat cholesteric liquid crystal layer 16Br and the corrugated cholesteric liquid crystal layer 14Br is preferably ± 20 nm or less.

Further, the light emitted by each light source of the laser projector is preferably circularly polarized, and its turning direction is preferably right-handed circular polarization, which is the same as the turning direction of the circularly polarized light reflected by the cholesteric liquid crystal layer. As a result, the light emitted by the laser projector can be more preferably reflected, and the amount of light passing through to the back surface side can be reduced.

Further, in the transparent screen of the present invention, two or more flat cholesteric liquid crystal layers 16 having the same selective reflection wavelength but different reflection circular polarization turning directions, and the circular polarization turning direction of the same selective reflection wavelength and reflected are reflected. May have two or more corrugated cholesteric liquid crystal layers 14 that are different from each other.

FIG. 6 is a cross-sectional view schematically showing another example of the transparent screen of the present invention.
The transparent screen 10c shown in FIG. 6 has a support 12, a flat cholesteric liquid crystal layer 16Bl having a selective reflection wavelength in the blue light region and reflecting left circular polarization, and a selective reflection wavelength in the green light region. A flat cholesteric liquid crystal layer 16Gl that reflects left circular polarization, a flat cholesteric liquid crystal layer 16Rl that has a selective reflection wavelength in the red light region and reflects left circular polarization, and a selective reflection wavelength in the blue light region. A flat cholesteric liquid crystal layer 16Br that has a right circular polarization and reflects a right circular polarization, and a flat cholesteric liquid crystal layer 16Gr that has a selective reflection wavelength in the green light region and reflects the right circular polarization, and is selected in the red light region. A flat cholesteric liquid crystal layer 16Rr having a reflection wavelength and reflecting right circular polarization, a corrugated cholesteric liquid crystal layer 14Br having a selective reflection wavelength in the blue light region and reflecting right circular polarization, and a green light region. It has a wave-shaped cholesteric liquid crystal layer 14Gr having a selective reflection wavelength and reflecting right circular polarization, and a wave-shaped cholesteric liquid crystal layer 14Rr having a selective reflection wavelength in the region of red light and reflecting right circular polarization.

That is, the transparent screen 10c has a 6-layer flat cholesteric liquid crystal layer 16 and a 3-layer corrugated cholesteric liquid crystal layer 14. Of the six layers of the flat cholesteric liquid crystal layer 16, three layers are the flat cholesteric liquid crystal layer 16 that reflects the left circular polarization, and the other three layers are the flat cholesteric liquid crystal layer 16 that reflects the right circular polarization. Further, the three selective reflection wavelengths of the flat cholesteric liquid crystal layer 16 that reflects the three layers of left circular polarization and the three selective reflection wavelengths of the flat cholesteric liquid crystal layer 16 that reflects the three layers of right circular polarization are the same. is there.

In this way, the laser projector combined with the transparent screen 10c irradiates unpolarized light by having the flat cholesteric liquid crystal layer 16 having the same selective reflection wavelength but different turning directions of the reflected circularly polarized light. Even so, almost all the light emitted by the laser projector can be reflected by the cholesteric liquid crystal layer, and the amount of light passing to the back surface side of the transparent screen 10c can be reduced.

In the example shown in FIG. 6, the flat cholesteric liquid crystal layer 16 having the same selective reflection wavelength but different turning directions of the reflected circular polarization is provided, but the present invention is not limited to this, and the selective reflection wavelength is the same. Therefore, it may be configured to have the corrugated cholesteric liquid crystal layer 14 having different turning directions of the reflected circular polarization, or as in the transparent screen 10d shown in FIG. 7, the turning of the reflected circular polarization having the same selective reflection wavelength. The structure may include a flat cholesteric liquid crystal layer 16 having different directions and a corrugated cholesteric liquid crystal layer 14 having the same selective reflection wavelength but different turning directions of reflected circular polarization.
The transparent screen 10d shown in FIG. 7 has a support 12, a flat cholesteric liquid crystal layer 16Bl having a selective reflection wavelength in the blue light region and reflecting left circular polarization, and a selective reflection wavelength in the green light region. A flat cholesteric liquid crystal layer 16Gl that reflects left circular polarization, a flat cholesteric liquid crystal layer 16Rl that has a selective reflection wavelength in the red light region and reflects left circular polarization, and a selective reflection wavelength in the blue light region. A wave-shaped cholesteric liquid crystal layer 14Bl that reflects left circular polarization and a wave-shaped cholesteric liquid crystal layer 14Gl that has a selective reflection wavelength in the green light region and reflects left circular polarization, and is selected in the red light region. A wave-shaped cholesteric liquid crystal layer 14Rl having a reflection wavelength and reflecting left circular polarization, a flat cholesteric liquid crystal layer 16Br having a selective reflection wavelength in the blue light region and reflecting right circular polarization, and a green light region. A flat cholesteric liquid crystal layer 16Gr having a selective reflection wavelength and reflecting right circular polarization, a flat cholesteric liquid crystal layer 16Rr having a selective reflection wavelength in the region of red light and reflecting right circular polarization, and blue light. A wave-shaped cholesteric liquid crystal layer 14Br having a selective reflection wavelength in the region of 1 and reflecting right circular polarization, and a wave-shaped cholesteric liquid crystal layer 14Gr having a selective reflection wavelength in the green light region and reflecting right circular polarization. It has a selective reflection wavelength in the region of red light, and has a corrugated cholesteric liquid crystal layer 14Rr that reflects right circular polarization.

Further, the transparent screen of the present invention has two or more flat cholesteric liquid crystal layers 16 having the same selective reflection wavelength and the same turning direction of reflected circularly polarized light, and between the two or more flat cholesteric liquid crystal layers 16. It may be configured to have a λ / 2 plate arranged in.

FIG. 8 is a cross-sectional view schematically showing another example of the transparent screen of the present invention.
The transparent screen 10e shown in FIG. 8 has a support 12, a flat cholesteric liquid crystal layer 16Br having a selective reflection wavelength in the blue light region and reflecting right circular polarization, and a selective reflection wavelength in the green light region. The flat cholesteric liquid crystal layer 16Gr that reflects the right circular polarization, the flat cholesteric liquid crystal layer 16Rr that has a selective reflection wavelength in the red light region and reflects the right circular polarization, the λ / 2 plate 18, and the blue color. A flat cholesteric liquid crystal layer 16Br having a selective reflection wavelength in the light region and reflecting right circular polarization, and a flat cholesteric liquid crystal layer 16Gr having a selective reflection wavelength in the green light region and reflecting right circular polarization. , A flat cholesteric liquid crystal layer 16Rr having a selective reflection wavelength in the red light region and reflecting right circular polarization, and a wave cholesteric liquid crystal layer having a selective reflection wavelength in the blue light region and reflecting right circular polarization. 14Br, a wave-shaped cholesteric liquid crystal layer 14Gr having a selective reflection wavelength in the green light region and reflecting right circular polarization, and a wave-shaped cholesteric having a selective reflection wavelength in the red light region and reflecting right circular polarization. It has a liquid crystal layer 14Rr.

That is, the transparent screen 10e has a 6-layer flat cholesteric liquid crystal layer 16 and a 3-layer corrugated cholesteric liquid crystal layer 14. The six-layer flat cholesteric liquid crystal layer 16 has three sets of two layers each of the same type of flat cholesteric liquid crystal layer 16 having the same selective reflection wavelength and the turning direction of the reflected circularly polarized light. Further, the λ / 2 plate 18 is arranged between the flat cholesteric liquid crystal layers 16 of the same type.

In this way, the laser combined with the transparent screen 10c by having the flat cholesteric liquid crystal layer 16 having the same selective reflection wavelength and the turning direction of the reflected circularly polarized light and having the λ / 2 plate 18 between them. When unpolarized light is emitted from the projector, the right circularly polarized light is reflected by the flat cholesteric liquid crystal layer 16 arranged in front of the λ / 2 plate 18, and the left circularly polarized light is transmitted. Since the transmitted left circularly polarized light is converted into right circularly polarized light by the λ / 2 plate 18, the converted right circularly polarized light is reflected by the flat cholesteric liquid crystal layer 16 arranged after the λ / 2 plate 18. As a result, almost all the light emitted by the laser projector can be reflected by the cholesteric liquid crystal layer, and the amount of light passing to the back surface side of the transparent screen 10c can be reduced.

In the example shown in FIG. 7, two or more flat cholesteric liquid crystal layers 16 having the same selective reflection wavelength and the turning direction of the reflected circularly polarized light are provided, and the λ / 2 plate 18 is provided between them. However, the present invention may be configured in which two or more corrugated cholesteric liquid crystal layers 14 having the same selective reflection wavelength and the turning direction of the reflected circularly polarized light are provided, and the λ / 2 plate 18 is provided between them. Alternatively, a corrugated cholesteric liquid crystal layer having two or more flat cholesteric liquid crystal layers 16 having the same selective reflection wavelength and the same turning direction of the reflected circular polarization, and having the same selective reflection wavelength and the same turning direction of the reflected circular polarization. 14 may be provided in two or more layers, and the λ / 2 plate 18 may be provided between the cholesteric liquid crystal layers of the same type.

The λ / 2 plate is a plate in which the in-plane retardation Re (λ) at a specific wavelength λ nm satisfies Re (λ) = λ / 2. This equation may be achieved at any wavelength in the visible light range (eg, 550 nm).
The λ / 2 plate 18 is not limited, and a known λ / 2 plate can be appropriately used.

Here, the thickness of the corrugated cholesteric liquid crystal layer 14 is preferably 0.1 μm to 30 μm, more preferably 0.5 μm to 20 μm, from the viewpoint of diffusivity and transparency.
The thickness of the flat cholesteric liquid crystal layer 16 is preferably 0.5 μm to 50 μm, more preferably 1 μm to 30 μm, from the viewpoint of diffusivity and transparency.
Further, the ratio of the thickness of the corrugated cholesteric liquid crystal layer 14 to the thickness of the flat cholesteric liquid crystal layer 16 may be appropriately adjusted from the viewpoint of achieving both diffusivity and transparency. The ratio of the thickness of the corrugated cholesteric liquid crystal layer 14 to the thickness of the flat cholesteric liquid crystal layer 16 is preferably corrugated cholesteric liquid crystal layer 14: flat cholesteric liquid crystal layer 16 = 1: 10 to 2: 1, preferably 1: 5. ~ 1: 1 is more preferable.
From the viewpoint of transparency, the thickness of the entire cholesteric liquid crystal layer is preferably 100 μm or less, more preferably 50 μm or less.

Further, the total light transmittance of the transparent screen is preferably 50% or more.
In the present invention, the total light transmittance may be measured according to JIS K 7361 using a commercially available measuring device such as NDH4000 or SH-7000 manufactured by Nippon Denshoku Kogyo Co., Ltd.

Further, in the transparent screen shown in FIG. 1 and the like, a plurality of cholesteric liquid crystal layers are formed on one support, but the present invention is not limited to this, and one or more cholesteric liquid crystals are formed on different supports. A liquid crystal layer may be formed, and a support on which the cholesteric liquid crystal layer is formed may be bonded with an adhesive or the like. That is, the transparent screen may have two or more supports.

Next, each component will be described in detail.
In the transparent screen 10, the support 12 is a plate-like object for supporting the cholesteric liquid crystal layer.
It is preferable that the support 12 has no color (that is, achromatic color) and has a total light transmittance of 80% or more. That is, the support 12 is preferably colorless and transparent. Further, the total light transmittance of the support 12 is more preferably 85% or more, further preferably 90% or more.
In the present invention, the total light transmittance may be measured according to JIS K 7361 using a commercially available measuring device such as NDH5000 or SH-7000 manufactured by Nippon Denshoku Kogyo Co., Ltd.

The material constituting the support 12 is not particularly limited, and for example, a cellulose-based polymer, a polycarbonate-based polymer, a polyester-based polymer, a (meth) acrylic polymer, a styrene-based polymer, a polyolefin-based polymer, a vinyl chloride-based polymer, or an amide-based polymer. , Imid-based polymers, sulfone-based polymers, polyether sulfone-based polymers, and polyether ether ketone-based polymers.
The support 12 may contain various additives such as a UV (ultraviolet) absorber, fine particles of a matting agent, a plasticizer, a deterioration inhibitor, and a release agent. Further, the support 12 may have a layer such as an orientation layer on the surface.
The support 12 preferably has low birefringence in the visible light region. For example, the phase difference of the support 12 at a wavelength of 550 nm is preferably 50 nm or less, more preferably 20 nm or less.

The thickness of the support 12 is not particularly limited, but is preferably 10 to 200 μm, more preferably 20 to 100 μm, from the viewpoint of thinning and handleability.
The above thickness is intended to be an average thickness, and the thickness of any five points of the support 12 is measured and arithmetically averaged.

Further, in the transparent screen of the present invention, the forming surface of the cholesteric liquid crystal layer of the support 12 does not have an uneven structure or a wavy structure, but is preferably a flat surface. As a result, the haze can be lowered and the transparency can be increased.

Next, the cholesteric liquid crystal layer (wave-shaped cholesteric liquid crystal layer and flat cholesteric liquid crystal layer) will be described.
The corrugated cholesteric liquid crystal layer and the flat cholesteric liquid crystal layer have the same configuration except that the layered structures of the bright and dark parts in the cross section are different, the forming materials and the like are the same, and the forming method is only partially different. Therefore, when it is not necessary to distinguish between the corrugated cholesteric liquid crystal layer and the flat cholesteric liquid crystal layer, it will be described as "cholesteric liquid crystal layer".
In one transparent screen, the liquid crystal composition constituting the corrugated cholesteric liquid crystal layer and the liquid crystal composition constituting the flat cholesteric liquid crystal layer may be the same or different. The combination of the liquid crystal composition and the chiral agent that can be used for producing the corrugated cholesteric liquid crystal layer is limited, whereas the flat cholesteric liquid crystal layer can be selected from many types of liquid crystal materials.

The selective reflection center wavelength (center wavelength λ of selective reflection) of the cholesteric liquid crystal layer in which the cholesteric liquid crystal phase is fixed depends on the pitch P (= spiral period) of the spiral structure in the cholesteric liquid crystal phase, and the cholesteric liquid crystal layer (cholesteric). It follows the relationship between the average refractive index n of (liquid crystal phase) and λ = n × P.
Here, the central wavelength λ of the selective reflection of the cholesteric liquid crystal layer means a wavelength at the center of gravity of the reflection peak of the circular polarization reflection spectrum measured from the normal direction of the cholesteric liquid crystal layer. As can be seen from the above equation, the center wavelength of selective reflection can be adjusted by adjusting the pitch of the spiral structure. That is, by adjusting the n value and the P value, for example, in order to selectively reflect either right-handed circularly polarized light or left-handed circularly polarized light with respect to blue light, the central wavelength λ is adjusted to make an apparent selection. The central wavelength of reflection can be set to a wavelength range of 420 nm or more and less than 500 nm. The apparent center wavelength of selective reflection is the wavelength at the center of gravity of the reflection peak of the circular polarization reflection spectrum of the cholesteric liquid crystal layer measured from the observation direction during practical use (when used as a projected image display member). means. Since the pitch of the cholesteric liquid crystal phase depends on the type of chiral auxiliary used together with the liquid crystal compound or the concentration thereof added, a desired pitch can be obtained by adjusting these.

The reflected light of the cholesteric liquid crystal layer having the cholesteric liquid crystal phase fixed is circularly polarized light. That is, the transparent screen of the present invention reflects circularly polarized light. Whether the reflected light is right-handed or left-handed depends on the twisting direction of the spiral of the cholesteric liquid crystal phase. The selective reflection of circular polarization by the cholesteric liquid crystal phase reflects the right circular polarization when the spiral twist direction of the cholesteric liquid crystal phase is right, and the left circular polarization when the spiral twist direction is left.
The direction of rotation of the cholesteric liquid crystal phase can be adjusted by the type of the liquid crystal compound forming the cholesteric liquid crystal layer or the type of the chiral auxiliary added.

For the measurement method of the twist direction (sense) or pitch of the spiral, see "Introduction to Liquid Crystal Chemistry Experiment", edited by Liquid Crystal Society of Japan, Sigma Publishing, 2007, p. 46, and "Liquid Crystal Handbook", Liquid Crystal Handbook Editorial Committee, Maruzen, p. The method can be used.

In the transparent screen of the present invention, the circularly polarized light reflected by the cholesteric liquid crystal layer is not particularly limited, and may be either right-handed circularly polarized light or left-handed circularly polarized light.

Further, when a plurality of cholesteric liquid crystal layers are provided, the selective reflection wavelength gradually becomes shorter or the selective reflection wavelength gradually becomes longer from the support 12 in the upward direction (distance direction). Is preferable.
By having such a configuration, that is, by reducing the difference in the selective reflection wavelengths of the adjacent cholesteric liquid crystal layers, the structure and characteristics of the adjacent cholesteric liquid crystal layers such as the pitch of the spiral structure in the adjacent cholesteric liquid crystal layers can be obtained. It is preferable in that a large difference can be prevented and a cholesteric liquid crystal layer having few defects can be formed.

The cholesteric liquid crystal layer is a layer formed by fixing the cholesteric liquid crystal phase. For such a cholesteric liquid crystal layer, as an example, a composition containing a liquid crystal compound and a chiral agent (invisible light cholesteric liquid crystal layer composition and upper layer composition) is prepared, and this composition is applied and dried, and if necessary. It can be formed by curing the composition accordingly and immobilizing the cholesteric liquid crystal phase.

(Liquid crystal compound)
The type of liquid crystal compound is not particularly limited.
In general, liquid crystal compounds can be classified into rod-shaped type (rod-shaped liquid crystal compound) and disk-shaped type (discotic liquid crystal compound, disk-shaped liquid crystal compound) according to their shape. Further, the rod-shaped type and the disk-shaped type are classified into a low molecular weight type and a high molecular weight type, respectively. A polymer generally refers to a polymer having a degree of polymerization of 100 or more (Polymer Physics / Phase Transition Dynamics, by Masao Doi, p. 2, Iwanami Shoten, 1992). In the present invention, any liquid crystal compound can be used. Further, two or more kinds of liquid crystal compounds may be used in combination.

The liquid crystal compound may have a polymerizable group. The type of the polymerizable group is not particularly limited, and a functional group capable of an addition polymerization reaction is preferable, and a polymerizable ethylenically unsaturated group or a ring-polymerizable group is more preferable. More specifically, as the polymerizable group, a (meth) acryloyl group, a vinyl group, a styryl group, an allyl group, an epoxy group, or an oxetane group is preferable, and a (meth) acryloyl group is more preferable.

As the liquid crystal compound, the liquid crystal compound represented by the following formula (I) is preferable in that the diffusion reflectivity of the cholesteric liquid crystal layer is more excellent.
Among them, the number of trans-1,4-cyclohexylene groups which may have a substituent represented by A is divided by m to obtain mc because the diffuse reflectivity of the cholesteric liquid crystal layer is more excellent. A liquid crystal compound satisfying mc> 0.1 is preferable, and a liquid crystal compound satisfying 0.4 ≦ mc ≦ 0.8 is more preferable.
The mc is a number represented by the following formula.
mc = (number of trans-1,4-cyclohexylene groups may have a substituent represented by A) ÷ m

During the ceremony
A represents a phenylene group which may have a substituent or a trans-1,4-cyclohexylene group which may have a substituent, and at least one of A has a substituent. Also shows a good trans-1,4-cyclohexylene group,
L is a single bond, or -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 = N-N = CH-, -CH = CH-, -C≡C-, -NHC (= O) -, -C (= O) NH-, -CH = N-, -N = CH-, -CH = CH-C (= O) O-, and -OC (= O) -CH = CH- Indicates a linking group selected from the group
m represents an integer from 3 to 12
Sp ¹ and Sp ² are independently ^one or ^two in a single bond or 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, respectively. One or more −CH ₂₋ are −O−, −S−, −NH−, −N (CH ₃ ) −, −C (= O) −, −OC (= O) −, or −C (= O) ) Indicates a linking group selected from the group consisting of groups substituted with O−.
Q ¹ and Q ² each independently represent a hydrogen atom or a polymerizable group selected from the group consisting of groups represented by the following formulas (Q-1) to (Q-5), where Either Q ¹ or Q ² shows a polymerizable group;

A is a phenylene group which may have a substituent or a trans-1,4-cyclohexylene group which may have a substituent. In the present specification, the phenylene group is preferably a 1,4-phenylene group.
At least one of A is a trans-1,4-cyclohexylene group which may have a substituent.
The m A's may be the same or different from each other.

m represents an integer of 3 to 12, 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 substituent which the phenylene group and the trans-1,4-cyclohexylene group may have in the formula (I) is not particularly limited, and is, for example, an alkyl group, a cycloalkyl group, an alkoxy group, or an alkyl ether. Examples thereof include a substituent selected from the group consisting of a group, an amide group, an amino group, a halogen atom, and a group composed of a combination of two or more of the above substituents. Further, examples of the substituent include the substituents represented by ^{-C (= O) -X 3 -Sp} 3 -Q 3 below. The phenylene group and the trans-1,4-cyclohexylene group may have 1 to 4 substituents. When having two or more substituents, the two or more substituents may be the same or different from each other.

As used herein, the alkyl group may be either linear or branched. The number of carbon atoms of the alkyl group is preferably 1 to 30, more preferably 1 to 10, and even more preferably 1 to 6. Examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, an isopentyl group and a neopentyl group. Examples thereof include a 1,1-dimethylpropyl group, an n-hexyl group, an isohexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, and a dodecyl group. The description of the alkyl group in the alkoxy group is the same as the description of the alkyl group. Further, in the present specification, specific examples of the alkylene group when referred to as an alkylene group include a divalent group obtained by removing one arbitrary hydrogen atom in each of the above-mentioned examples of an alkyl group. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

In the present specification, the number of carbon atoms of the cycloalkyl group is preferably 3 or more, more preferably 5 or more, preferably 20 or less, more preferably 10 or less, further preferably 8 or less, and particularly preferably 6 or less. Examples of the cycloalkyl group include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group and the like.

Substituents that the phenylene group and the trans-1,4-cyclohexylene group may have include an alkyl group, an alkoxy group, and a 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 a nitrogen atom forming a ring structure with Q ³ and Sp ^3. Shown. Sp ³ and Sp ⁴ are independently one or two in a single bond or 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, respectively. One or more −CH ₂₋ are −O−, −S−, −NH−, −N (CH ₃ ) −, −C (= O) −, −OC (= O) −, or −C (= O) ) Indicates a linking group selected from the group consisting of groups substituted with O−.
In Q ³ and Q ⁴ , each of the hydrogen atom, cycloalkyl group, and cycloalkyl group has one or more -CH ₂ − -O-, -S-, -NH-, and -N (CH _3). )-, -C (= O)-, -OC (= O)-, or -C (= O) O-substituted group, or represented by formulas (Q-1) to (Q-5). Shows any polymerizable group selected from the group consisting of the groups to be.

One or more -CH ₂ − in a cycloalkyl group is −O−, −S−, −NH−, −N (CH ₃ ) −, −C (= O) −, −OC (= O) Specific examples of the group substituted with − or −C (= O) O− include a tetrahydrofuranyl group, a pyrrolidinyl group, an imidazolidinyl group, a pyrazoridinyl group, a piperidyl group, a piperazinyl group, and a morphornyl group. .. Of these, a tetrahydrofuranyl group is preferable, and a 2-tetrahydrofuranyl group is more preferable.

In formula (I), L is a single bond or −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)- The linking group selected from the group consisting of CH = CH− is shown. L is preferably −C (= O) O− or −OC (= O) −. The m L's may be the same or different from each other.

Sp ¹ and Sp ² are independently ^one or ^two in a single bond or 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, respectively. One or more −CH ₂₋ are −O−, −S−, −NH−, −N (CH ₃ ) −, −C (= O) −, −OC (= O) −, or −C (= O) Indicates a linking group selected from the group consisting of groups substituted with O−. Sp ¹ and Sp ² each have the number of carbon atoms to which a linking group selected from the group consisting of -O-, -OC (= O)-, and -C (= O) O- is bonded to both ends independently. Selected from the group consisting of 1 to 10 linear alkylene groups, -OC (= O)-, -C (= O) O-, -O-, and 1 to 10 carbon linear alkylene groups. It is preferably a linking group composed of one or a combination of two or more groups, and more preferably a linear alkylene group having 1 to 10 carbon atoms having —O— bonded to both ends.

Q ¹ and Q ² each independently represent a hydrogen atom or a polymerizable group selected from the group consisting of groups represented by the following formulas (Q-1) to (Q-5). However, either Q ¹ or Q ² shows a polymerizable group.

As the polymerizable group, an acryloyl group (formula (Q-1)) or a methacryloyl group (formula (Q-2)) is preferable.

Specific examples of the liquid crystal compound include a liquid crystal compound represented by the following formula (I-11), a liquid crystal compound represented by the formula (I-21), and a liquid crystal compound represented by the formula (I-31). Can be mentioned. In addition to the above, the compound represented by the formula (I) of JP2013-12631A, the compound represented by the formula (I) of JP2010-70543A, and the formula of JP-A-2008-291218. Compound represented by (I), compound represented by formula (I) of Patent No. 4725516, compound represented by general formula (II) of JP2013-087109, JP2007-176927 The compound described in paragraph [0043] of the above, the compound represented by the formula (1-1) of JP-A-2009-286885, the compound represented by the general formula (I) of WO2014 / 10325, JP-A-2016-81035. Known compounds described in the compounds represented by the formula (1) of JP-A and the compounds represented by the formulas (2-1) and (2-2) of JP-A-2016-121339 are Can be mentioned.

Liquid crystal compound represented by the formula (I-11)

In the formula, R ¹¹ represents a hydrogen atom, a linear or branched alkyl group having 1 to 12 carbon atoms, or −Z ¹² −Sp ¹² −Q ¹² .
L ¹¹ indicates a single bond, −C (= O) O−, or −O (C = O) −.
L ¹² indicates −C (= O) O−, −OC (= O) −, or −CONR ²⁻ .
R ² represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.
Z ¹¹ and Z ¹² are independently single-bonded, -O-, -NH-, -N (CH ₃ )-, -S-, -C (= O) O-, -OC (= O)-, respectively. -OC (= O) O-, ^{or, -C (= O) NR 12} - indicates,
R ¹² indicates a hydrogen atom or −Sp ¹² −Q ¹²
Sp ¹¹ and Sp ¹² are each independently a single bond, a linear or branched alkylene group having from carbon atoms 1 be replaced by Q ¹¹ 12 or carbon atoms which may be substituted with Q ^11, 1 From 12 to 12 linear or branched alkylene groups, any one or more of -CH ₂ − is -O-, -S-, -NH-, -N (Q ¹¹ )-, or -C (= O). )-Indicates the linking group obtained by substituting with-
Q ¹¹ is a hydrogen atom, a cycloalkyl group, one in the cycloalkyl group or two or more -CH ₂ - is -O -, - S -, - NH -, - N (CH 3) -, - C (= A group consisting of groups substituted with O)-, -OC (= O)-, or -C (= O) O-, or groups represented by the formulas (Q-1) to (Q-5). Indicates a polymerizable group selected from
Q ¹² represents a polymerizable group selected from the group consisting of groups represented by hydrogen atom or formula (Q-1) ~ formula (Q-5),
l ¹¹ indicates an integer from 0 to 2
m ¹¹ indicates an integer of 1 or 2 and represents
n ¹¹ indicates an integer from 1 to 3 and represents
A plurality of R ^11, a plurality of L ^11, a plurality of L ^12, a plurality of l ^11, a plurality of Z ^11, a plurality of Sp ^11, and a plurality of Q ¹¹ may each be the same or different from each other.
Further, the liquid crystal compound represented by the formula (I-11) is polymerizable as R ¹¹ selected from the group consisting of groups in which Q ¹² is represented by the formulas (Q-1) to (Q-5). It contains at least one of the base −Z ¹² −Sp ¹² −Q ¹² .
The liquid crystal compound represented by formula (I-11) is, Z ¹¹ is -C (= O) O- or ^{-C (= O) NR 12 -} , and, Q ¹¹ has the formula (Q-1) ~ It is preferably −Z ¹¹ −Sp ¹¹ −Q ¹¹ which is a polymerizable group selected from the group consisting of the groups represented by the formula (Q-5). The liquid crystal compound represented by formula (I-11) as R ^11, Z ¹² is -C (= O) O- or ^{-C (= O) NR 12 -} , and, Q ¹² has the formula (Q -1) It is preferably −Z ¹² −Sp ¹² −Q ¹² which is a polymerizable group selected from the group consisting of the groups represented by the formulas (Q-5).

The 1,4-cyclohexylene groups contained in the liquid crystal compound represented by the formula (I-11) are all trans-1,4-cyclohexylene groups.
As a preferable embodiment of the liquid crystal compound represented by the formula (I-11), L ¹¹ is a single bond, l ¹¹ is 1 (dicyclohexyl group), and Q ¹¹ is a formula (Q-1) to (Q-5). ) Is a polymerizable group selected from the group consisting of the groups represented by).
As another preferred embodiment of the liquid crystal compound represented by the formula (I-11), m ¹¹ represents 2, l ¹¹ represents 0, and both R ¹¹ represent −Z ¹² −Sp ¹² −Q ¹² . , Q ¹² and the like are compounds which are polymerizable groups selected from the group consisting of groups represented by the formula (Q-1) ~ formula (Q-5).

Liquid crystal compound represented by the formula (I-21)

In the formula, Z ²¹ and Z ²² each independently represent a trans-1,4-cyclohexylene group which may have a substituent or a phenylene group which may have a substituent.
Each of the above substituents is 1 to 4 substituents independently selected from the group consisting of -CO-X ^21- Sp ^23- Q ²³ , an alkyl group, and an alkoxy group.
m21 represents an integer of 1 or 2, n21 represents an integer of 0 or 1,
When m21 indicates 2, n21 indicates 0,
When m21 indicates 2, the two Z ^21s may be the same or different.
At least one of Z ²¹ and Z ²² is a phenylene group which may have a substituent and is a phenylene group.
L ²¹ , L ²² , L ²³ and L ²⁴ are independently single-bonded or -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- Indicates a linking group selected from the group consisting of OC (= O) -CH = CH-.
X ²¹ indicates -O-, -S-, or -N (Sp ^25- Q ²⁵ )-or indicates a nitrogen atom that forms a ring structure with Q ²³ and Sp ²³ .
r ²¹ represents an integer from 1 to 4
Sp ²¹ , Sp ²² , Sp ²³ , and Sp ²⁵ are independently single-bonded or linear or branched alkylene groups with 1 to 20 carbon atoms and linear or branched alkylene groups with 1 to 20 carbon atoms, respectively. One or more -CH ₂ − in the group is −O−, −S−, −NH−, −N (CH ₃ ) −, −C (= O) −, −OC (= O) −, Alternatively, a linking group selected from the group consisting of groups substituted with −C (= O) O− is indicated.
Q ²¹ and Q ²² each independently represent any polymerizable group selected from the group consisting of the groups represented by the formulas (Q-1) to (Q-5).
In Q ²³ , one or more -CH _2- in a hydrogen atom, a cycloalkyl group, and a cycloalkyl group are -O-, -S-, -NH-, -N (CH ₃ )-, -C (= Select from the group consisting of groups substituted with O)-, -OC (= O)-, or -C (= O) O-, and groups represented by the formulas (Q-1) to (Q-5). One of the polymerizable groups, or when X ²¹ is a nitrogen atom forming a ring structure with Q ²³ and Sp ²³ , shows a single bond.
Q ²⁵ is a hydrogen atom, a cycloalkyl group, one or two or more -CH ₂ in the cycloalkyl group - is -O -, - S -, - NH -, - N (CH 3) -, - C ( It consists of a group substituted with = O)-, -OC (= O)-, or -C (= O) O-, or a group represented by the formulas (Q-1) to (Q-5). Q ²⁵ is not a hydrogen atom when it represents any polymerizable group selected from the group and Sp ²⁵ is a single bond.

The liquid crystal compound represented by the formula (I-21) preferably has a structure in which 1,4-phenylene groups and trans-1,4-cyclohexylene groups are alternately present, for example, m21 is 2. n21 is 0, and, if Z ²¹ are each optionally substituted trans-1,4-cyclohexylene group, an arylene group optionally having a substituent from Q ²¹ side, Alternatively, m21 is 1, n21 is 1, Z ²¹ is an arylene group which may have a substituent, and Z ²² is an arylene group which may have a substituent. Is preferable.

Liquid crystal compound represented by formula (I-31);

In the formula, R ³¹ and R ³² are independently selected groups from the group consisting of an alkyl group, an alkoxy group, and -C (= O) -X ^31- Sp ^33- Q ³³ .
n31 and n32 independently represent an integer from 0 to 4, respectively.
X ³¹ indicates a single bond, -O-, -S-, or -N (Sp ^34- Q ³⁴ )-or indicates a nitrogen atom forming a ring structure with Q ³³ and Sp ³³ .
Z ³¹ represents a phenylene group which may have a substituent and
Z ³² represents a trans-1,4-cyclohexylene group which may have a substituent or a phenylene group which may have a substituent.
Each of the above substituents is 1 to 4 substituents independently selected from the group consisting of an alkyl group, an alkoxy group, and -C (= O) -X ^31- Sp ^33- Q ³³ .
m31 represents an integer of 1 or 2, m32 represents an integer of 0-2,
Two Z ³¹ when m31 and m32 indicates 2, Z ³² may be the same or different and
L ³¹ and L ³² are independently single-bonded or -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)- Indicates a linking group selected from the group consisting of CH = CH−.
Sp ³¹ , Sp ³² , Sp ³³ and Sp ³⁴ are independently single-bonded or linear or branched alkylene groups with 1 to 20 carbon atoms and linear or branched alkylene groups with 1 to 20 carbon atoms, respectively. In one or more of -CH ₂ − are -O-, -S-, -NH-, -N (CH ₃ )-, -C (= O)-, -OC (= O)-, or Indicates a linking group selected from the group consisting of groups substituted with −C (= O) O−.
Q ³¹ and Q ³² each independently represent any polymerizable group selected from the group consisting of the groups represented by the formulas (Q-1) to (Q-5).
In Q ³³ and Q ³⁴ , one or more -CH ₂ − in the hydrogen atom, cycloalkyl group, and cycloalkyl group are -O-, -S-, -NH-, and -N (CH ₃₎ independently of each other. )-, -C (= O)-, -OC (= O)-, or -C (= O) O-substituted group, or in formulas (Q-1) to (Q-5) Representing any polymerizable group selected from the group consisting of the represented groups, Q ³³ may exhibit a single bond when forming a ring structure with X ³¹ and Sp ^33, with Sp ³⁴ In a single bond, Q ³⁴ is not a hydrogen atom.
As the liquid crystal compound represented by the formula (I-31), particularly preferable compounds include a compound in which Z ³² is a phenylene group and a compound in which m 32 is 0.

The compound represented by the formula (I) preferably has a partial structure represented by the following formula (II).
In formula (II), black circles indicate the bonding positions with other parts of formula (I). The partial structure represented by the formula (II) may be included as a part of the partial structure represented by the following formula (III) in the formula (I).

Wherein R ¹ and R ² each independently represent a hydrogen atom, an alkyl group, an alkoxy group, and is selected from the group consisting of groups represented by ^{-C (= O) -X 3 -Sp} 3 -Q 3 It is a base. Here, X ³ represents a single bond, -O-, -S-, or -N (Sp ^4- Q ⁴ )-, or a nitrogen atom forming a ring structure with Q ³ and Sp ^3. Shown. X ³ is preferably single bond or −O−. R ¹ and R ² is preferably a ^{-C (= O) -X 3 -Sp} 3 -Q 3. Further, it is preferable that R ¹ and R ² are the same as each other. The bonding position of R ¹ and R ² to each phenylene group is not particularly limited.

Sp ³ and Sp ⁴ are independently one or two in a single bond or 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, respectively. The above -CH ₂ -is -O-, -S-, -NH-, -N (CH ₃ )-, -C (= O)-, -OC (= O)-, or -C (= O). Indicates a linking group selected from the group consisting of groups substituted with O−. As Sp ³ and Sp ⁴ , independently, a linear or branched alkylene group having 1 to 10 carbon atoms is preferable, a linear alkylene group having 1 to 5 carbon atoms is more preferable, and a direct chain having 1 to 3 carbon atoms is preferable. The alkylene group of the chain is more preferred.
In Q ³ and Q ⁴ , each of the hydrogen atom, cycloalkyl group, and cycloalkyl group has one or more -CH ₂ − -O-, -S-, -NH-, and -N (CH _3). )-, -C (= O)-, -OC (= O)-or -C (= O) O-substituted groups, or represented by formulas (Q-1) to (Q-5). Shows any polymerizable group selected from the group consisting of the groups to be.

The compound represented by the formula (I) also preferably has a structure represented by the following formula (II-2), for example.

In the formula, A ¹ and A ² independently represent a phenylene group which may have a substituent or a trans-1,4-cyclohexylene group which may have a substituent, and the above-mentioned substituents are Each is independently 1 to 4 substituents selected from the group consisting of an alkyl group, an alkoxy group, and -C (= O) -X ^3- Sp ^3- Q ³ .
L ¹ , L ² and L ³ are single bonds, or -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)- Indicates a linking group selected from the group consisting of CH = CH−.
n1 and n2 each independently represent an integer from 0 to 9, and n1 + n2 is 9 or less.
The definitions of Q ¹ , Q ² , Sp ¹ , and Sp ² are synonymous with the definitions of each group in the above formula (I). The definitions of X ³ , Sp ³ , Q ³ , R ¹ , and R ² are synonymous with the definitions of each group in the above formula (II).

Examples of the liquid crystal compound represented by the formula (I) and satisfying 0.4 ≦ mc ≦ 0.8 are described in paragraphs [0051] to [0054] of International Publication No. 2016/047648. The compounds that have been used are exemplified.

In addition, you may use 2 or more liquid crystal compounds in combination. For example, two or more liquid crystal compounds represented by the formula (I) may be used in combination.
Among them, the liquid crystal compound represented by the above formula (I), which satisfies 0.4 ≦ mc ≦ 0.8, and the liquid crystal compound represented by the formula (I), 0.1. It is preferable to use a liquid crystal compound satisfying <mc <0.3.

Examples of the liquid crystal compound represented by the formula (I) and satisfying 0.1 <mc <0.3 are described in paragraphs [0055] to [0058] of International Publication No. 2016/0447648. The compounds that have been used are exemplified.

The liquid crystal compound used in the present invention is a compound represented by the following formula (IV) described in JP-A-2014-198814, particularly one (meth) acrylate group represented by the formula (IV). A polymerizable liquid crystal compound having the above is also preferably used.

Equation (IV)
Wherein (IV), A ¹ represents an alkylene group having 2 to 18 carbon atoms, two or more CH ₂ that is not one of the CH ₂ or adjacent in the alkylene group is substituted by -O- May;
Z ¹ represents −C (= O) −, −OC (= O) − or single bond;
Z ² represents −C (= O) − or −C (= O) −CH = CH−;
R ¹ represents a hydrogen atom or a methyl group;
R ² has a hydrogen atom, a halogen atom, a linear alkyl group having 1 to 4 carbon atoms, a methoxy group, an ethoxy group, and a phenyl group, a vinyl group, a formyl group, a nitro group, and a cyano group which may have a substituent. , Acetyl group, acetoxy group, N-acetylamide group, acryloylamino group, N, N-dimethylamino group or maleimide group, methacryloylamino group, allyloxy group, allyloxycarbamoyl group, alkyl group having 1 to 4 carbon atoms. Represents a certain N-alkyloxycarbamoyl group, N- (2-methacryloyloxyethyl) carbamoyloxy group, N- (2-acryloyloxyethyl) carbamoyloxy group or a structure represented by the following formula (IV-2);
L ¹ , L ² , L ³ and L ⁴ are independently alkyl groups having 1 to 4 carbon atoms, alkoxy groups having 1 to 4 carbon atoms, alkoxycarbonyl groups having 2 to 5 carbon atoms, and 2 to 4 carbon atoms. Represents an acyl group, a halogen atom or a hydrogen atom of, and at least one of L ¹ , L ² , L ³ and L ⁴ represents a group other than a hydrogen atom.

-Z ^5- T-Sp-P formula (IV-2)
In formula (IV-2), P represents an acrylic group, a methacryl group or a hydrogen atom, Z ⁵ is a single bond, -C (= O) O-, -OC (= O)-, -C (= O). NR ¹ − (R ¹ represents a hydrogen atom or a methyl group), −NR ¹ C (= O) −, −C (= O) S−, or −SC (= O) −, where T is 1 , 4-Phenylene, Sp represents a divalent aliphatic group having 1 to 12 carbon atoms which may have a substituent, and one CH ₂ in the aliphatic group or _two or more non-adjacent groups. CH ₂ may be substituted with −O−, −S−, −OC (= O) −, −C (= O) O− or −OCOO−. ).

The compound represented by the above formula (IV) is preferably a compound represented by the following formula (V).
Equation (V)
In equation (V), n1 represents an integer of 3-6;
R ¹¹ represents a hydrogen atom or a methyl group;
Z ¹² represents -C (= O)-or -C (= O) -CH = CH-;
R ¹² is represented by a hydrogen atom, a linear alkyl group having 1 to 4 carbon atoms, a methoxy group, an ethoxy group, a phenyl group, an acryloylamino group, a methacryloylamino group, an allyloxy group, or the following formula (IV-3). Represents the structure.
-Z ^51- T-Sp-P formula (IV-3)
In formula (IV-3), P represents an acrylic or methacrylic group;
Z ⁵¹ represents -C (= O) O- or -OC (= O)-; T represents 1,4-phenylene;
Sp represents a divalent aliphatic group having 2 to 6 carbon atoms which may have a substituent. One CH ₂ or non-adjacent two or more CH ₂ in the aliphatic groups, -O -, - OC (= O) -, - C (= O) O- or -OC (= O) O It may be replaced with −.

The above n1 represents an integer of 3 to 6, and is preferably 3 or 4.
The Z ¹² represents −C (= O) − or −C (= O) −CH = CH−, and preferably −C (= O) −.
The above R ¹² is represented by a hydrogen atom, a linear alkyl group having 1 to 4 carbon atoms, a methoxy group, an ethoxy group, a phenyl group, an acryloylamino group, a methacryloylamino group, an allyloxy group, or the above formula (IV-3). It is more preferable to represent a methyl group, an ethyl group, a propyl group, a methoxy group, an ethoxy group, a phenyl group, an acryloylamino group, a methacryloylamino group, or a group represented by the above formula (IV-3). , Methyl group, ethyl group, methoxy group, ethoxy group, phenyl group, acryloylamino group, methacryloylamino group, or a structure represented by the above formula (IV-3) is more preferable.

Examples of the compound represented by the formula (IV) include the compounds described in paragraphs [0020] to [0036] of JP-A-2014-198814.

Examples of the liquid crystal compound used in the present invention include compounds represented by the following formula (VI), which are also described in JP-A-2014-198814, particularly (meth) acrylate represented by the following formula (VI). Liquid crystal compounds having no group are also preferably used.

Equation (VI)
In formula (VI), Z ³ represents −C (= O) − or −CH = CH—C (= O) −;
Z ⁴ represents −C (= O) − or −C (= O) −CH = CH−;
Each of R ³ and R ⁴ independently has a hydrogen atom, a halogen atom, a linear alkyl group having 1 to 4 carbon atoms, a methoxy group, an ethoxy group, and an aromatic ring and a cyclohexyl group which may have a substituent. Carbon number of vinyl group, formyl group, nitro group, cyano group, acetyl group, acetoxy group, acryloylamino group, N, N-dimethylamino group, maleimide group, methacryloylamino group, allyloxy group, allyloxycarbamoyl group, alkyl group Is represented by an N-alkyloxycarbamoyl group in which is 1 to 4, an N- (2-methacryloyloxyethyl) carbamoyloxy group, an N- (2-acryloyloxyethyl) carbamoyloxy group, or the following formula (VI-2). Represents the structure;
L ⁵ , L ⁶ , L ⁷ and L ⁸ are independently alkyl groups having 1 to 4 carbon atoms, alkoxy groups having 1 to 4 carbon atoms, alkoxycarbonyl groups having 2 to 5 carbon atoms, and 2 to 4 carbon atoms. Represents an acyl group, a halogen atom or a hydrogen atom of, and at least one of L ⁵ , L ⁶ , L ⁷ and L ⁸ represents a group other than a hydrogen atom.

-Z ^5- T-Sp-P formula (VI-2)
In formula (VI-2), P represents an acrylic group, a methacryl group or a hydrogen atom, and Z ⁵ is −C (= O) O−, −OC (= O) −, −C (= O) NR ¹ −. (R ¹ represents a hydrogen atom or a methyl group), -NR ¹ C (= O)-, -C (= O) S-, or -SC (= O)-, and T represents 1,4-phenylene. , And Sp represents a divalent aliphatic group having 1 to 12 carbon atoms which may have a substituent. However, 2 or more CH ₂ not one CH ₂ or adjacent in the aliphatic groups, -O -, - S -, - OC (= O) -, - C (= O) O- or - It may be replaced with OC (= O) O−.

The compound represented by the above formula (VI) is preferably a compound represented by the following formula (VII).
Equation (VII)
In formula (VII), Z ¹³ represents -C (= O)-or -C (= O) -CH = CH-;
Z ¹⁴ represents −C (= O) − or −CH = CH—C (= O) −;
R ¹³ and R ¹⁴ are independently hydrogen atoms, linear alkyl groups having 1 to 4 carbon atoms, methoxy groups, ethoxy groups, phenyl groups, acryloylamino groups, methacryloylamino groups, allyloxy groups, or the above formula (IV). Represents the structure represented by -3).

The Z ¹³ represents −C (= O) − or −C (= O) −CH = CH−, and preferably −C (= O) −.
R ¹³ and R ¹⁴ are independently hydrogen atoms, linear alkyl groups having 1 to 4 carbon atoms, methoxy groups, ethoxy groups, phenyl groups, acryloylamino groups, methacryloylamino groups, allyloxy groups or the above formula (IV-). Representing the structure represented by 3), a methyl group, an ethyl group, a propyl group, a methoxy group, an ethoxy group, a phenyl group, an acryloylamino group, a methacryloylamino group, or a structure represented by the above formula (IV-3). It is preferable to represent a methyl group, an ethyl group, a methoxy group, an ethoxy group, a phenyl group, an acryloylamino group, a methacryloylamino group, or a structure represented by the above formula (IV-3).

Examples of the compound represented by the formula (VI) include the compounds described in paragraphs [0042] to [0049] of JP-A-2014-198814.

As the liquid crystal compound used in the present invention, the compound represented by the following formula (VIII), which is also described in JP-A-2014-198814, particularly the two compounds represented by the following formula (VIII) ( A polymerizable liquid crystal compound having a meta) acrylate group is also preferably used.

Equation (VIII)
Wherein (VIII), A ² and A ³ each independently represents an alkylene group having 2 to 18 carbon atoms, two or more CH ₂ that is not one of the CH ₂ or adjacent in the alkylene group, - May be replaced with O-;
Z ⁵ represents -C (= O)-, -OC (= O)-or single bond;
Z ⁶ represents -C (= O)-, -C (= O) O- or a single bond;
R ⁵ and R ⁶ each independently represent a hydrogen atom or a methyl group;
L ⁹ , L ¹⁰ , L ¹¹ and L ¹² are independently alkyl groups having 1 to 4 carbon atoms, alkoxy groups having 1 to 4 carbon atoms, alkoxycarbonyl groups having 2 to 5 carbon atoms, and 2 to 4 carbon atoms. Represents an acyl group, a halogen atom or a hydrogen atom of, and at least one of L ⁹ , L ¹⁰ , L ¹¹ and L ¹² represents a group other than a hydrogen atom.

The compound represented by the above formula (VIII) is preferably a compound represented by the following formula (IX).
Equation (IX)
In formula (IX), n2 and n3 each independently represent an integer of 3-6;
R ¹⁵ and R ¹⁶ each independently represent a hydrogen atom or a methyl group.

In the formula (IX), n2 and n3 each independently represent an integer of 3 to 6, and it is preferable that n2 and n3 are 4.
In formula (IX), R ¹⁵ and R ¹⁶ each independently represent a hydrogen atom or a methyl group, and it is preferable that R ¹⁵ and R ¹⁶ represent a hydrogen atom.

Examples of the compound represented by the formula (VIII) include the compounds described in paragraphs [0056] and [0057] of JP-A-2014-198814.

These liquid crystal compounds can be produced by a known method.

(Chiral agent (chiral compound))
The composition comprises a chiral agent.
The type of chiral auxiliary is not particularly limited. The chiral agent may be liquid crystal or non-liquid crystal. The chiral agents are various known chiral agents (for example, liquid crystal device handbook, Chapter 3, 4-3, TN (Twisted Nematic), STN (Super Twisted Nematic) chiral agents, page 199, Japan Society for the Promotion of Science 142. You can choose from (described in 1989, edited by the committee). Chiral agents generally contain an asymmetric carbon atom. However, an axial asymmetric compound or a surface asymmetric compound that does not contain an asymmetric carbon atom can also be used as a chiral agent. Examples of axially asymmetric or surface asymmetric compounds include binaphthyl, helicene, paracyclophane and derivatives thereof. The chiral agent may have a polymerizable group.

The content of the chiral agent in the composition is preferably 0.5 to 30% by mass with respect to the total mass of the liquid crystal compound. A smaller amount of chiral agent is preferred because it tends not to affect the liquid crystallinity. Therefore, as the chiral agent, a compound having a strong twisting force is preferable so that a desired twisting orientation of a spiral pitch can be achieved even in a small amount.
Examples of the chiral agent exhibiting such a strong twisting force include JP-A-2002-302487, JP-A-2002-80478, JP-A-2002-80851, JP-A-2002-179668, and JP-A-2002. 179670, 2002-338575, 2002-180051, 62-81354, WO2002 / 00195, 2011-241215, 2003-287623 , JP-A-2002-302487, JP-A-2002-80478, JP-A-2002-80851, and the chiral agents described in JP-A-2014-034581 and LC-756 manufactured by BASF. Can be mentioned.

(Arbitrary ingredient)
The composition may contain components other than the liquid crystal compound and the chiral agent.

(Polymerization initiator)
The composition may contain a polymerization initiator. In particular, when the liquid crystal compound has a polymerizable group, it is preferable that the composition contains a polymerization initiator.
The polymerization initiator is preferably a photopolymerization initiator capable of initiating a polymerization reaction by irradiation with ultraviolet rays. Examples of the photopolymerization initiator include α-carbonyl compounds (described in US Pat. Nos. 2,376,661 and 236,670), acidoin ether (described in US Pat. No. 2,448,828), and α-hydrogen-substituted aromatic acidoin. Compounds (described in US Pat. No. 2722512), polynuclear quinone compounds (described in US Pat. Nos. 3,043127 and 2951758), a combination of triarylimidazole dimer and p-aminophenylketone (US Pat. No. 3,549,376). (Described in the specification), aclysine and phenazine compounds (Japanese Patent Laid-Open No. 60-105667, US Pat. No. 4,239,850), oxadiazole compounds (described in US Pat. No. 4,212,970), and the like.
The content of the polymerization initiator in the composition is not particularly limited, but is preferably 0.1 to 20% by mass, more preferably 1 to 8% by mass, based on the total mass of the liquid crystal compound.

(Orientation control agent (orientation agent))
The composition may contain an orientation control agent. The inclusion of the orientation control agent in the composition allows stable or rapid formation of the cholesteric liquid crystal phase.
Examples of the orientation control agent include a fluorine-containing (meth) acrylate-based polymer, a compound represented by the general formulas (X1) to (X3) described in WO2011 / 162291, and paragraph [0007] of JP2012-211306A. ] To [0029], the compounds described in paragraphs [0020] to [0031] of JP2013-47204A, the compounds described in paragraphs [0165] to [0170] of WO2016 / 909648, WO2016. / 092844, paragraphs [0077] to [0081], and general formulas (Cy201) to (Cy211) described in Japanese Patent No. 4592225 can be mentioned. It may contain two or more kinds selected from these. These compounds can reduce or substantially horizontally align the molecules of the liquid crystal compound at the air interface of the layer. In addition, although "horizontal orientation" in the present specification means that the long axis of the liquid crystal molecule and the film surface are parallel, it does not require that they are strictly parallel, and in this specification, it is referred to as a horizontal plane. It shall mean an orientation with an inclination angle of less than 20 °.
The orientation control agent may be used alone or in combination of two or more.
The content of the orientation control agent in the composition is not particularly limited, but is preferably 0.01 to 10% by mass, more preferably 0.01 to 5% by mass, and 0.01 to 0.01 to the total mass of the liquid crystal compound. 1% by mass is more preferable.

(solvent)
The composition may contain a solvent.
Examples of the solvent include water and organic solvents. Examples of the organic solvent include amides such as N and N-dimethylformamide; sulfoxides such as dimethyl sulfoxide; heterocyclic compounds such as pyridine; hydrocarbons such as benzene and hexane; alkyl halides such as chloroform and dichloromethane; acetic acid. Esters such as methyl, butyl acetate and propylene glycol monoethyl ether acetate; ketones such as acetone, methyl ethyl ketone, cyclohexanone and cyclopentanone; ethers such as tetrahydrofuran and 1,2-dimethoxyethane; 1,4-butanediol di Acetate; etc. These may be used alone or in combination of two or more.

(Other additives)
The composition is one or more kinds of antioxidants, ultraviolet absorbers, sensitizers, stabilizers, plasticizers, chain transfer agents, polymerization inhibitors, defoamers, leveling agents, thickeners. , Flame Retardants, Surfactants, Dispersants, and Other Additives such as Coloring Materials such as Dyes and Pigments.

Next, a method for producing the transparent screen of the present invention will be described.
In the transparent screen of the present invention, a cholesteric liquid crystal layer is formed on the support 12 by a coating method using a composition (upper layer composition) containing a liquid crystal compound and a chiral agent as described above, and further formed. It can be produced by sequentially forming a cholesteric liquid crystal layer by a coating method using a composition (upper layer composition) containing a liquid crystal compound and a chiral agent as described above on the cholesteric liquid crystal layer.

As an example, a method for manufacturing a transparent screen having a flat cholesteric liquid crystal layer 16Rr on a support 12 and a corrugated cholesteric liquid crystal layer 14Rr on a flat cholesteric liquid crystal layer 16Rr as shown in FIG. 1 will be described. To do.

First, a composition (invisible light cholesteric liquid crystal layer composition) containing the above-mentioned liquid crystal compound and chiral agent is prepared, and the prepared composition is applied to the support 12.
The coating method is not particularly limited, and examples thereof include a wire bar coating method, an extrusion coating method, a direct gravure coating method, a reverse gravure coating method, and a die coating method.
If necessary, a treatment for drying the cholesteric liquid crystal layer composition applied to the support 12 may be carried out after the application. By carrying out the drying treatment, the solvent can be removed from the applied composition.

Next, the cholesteric liquid crystal layer composition (composition layer (coating film)) coated on the support 12 is heated to orient the liquid crystal compounds in the composition to obtain a cholesteric liquid crystal phase. At this time, the cholesteric liquid crystal phase is in a state in which a bright portion and a dark portion parallel to the support 12 are laminated.
The liquid crystal phase transition temperature of the cholesteric liquid crystal layer composition is preferably in the range of 10 to 250 ° C., more preferably in the range of 10 to 150 ° C. from the viewpoint of manufacturing suitability.
As preferred heating conditions, it is preferable to heat the composition at 40 to 100 ° C. (preferably 60 to 100 ° C.) for 0.5 to 5 minutes (preferably 0.5 to 2 minutes).

When the liquid crystal compound has a polymerizable group, the liquid crystal compound is oriented to obtain a cholesteric liquid crystal phase, and then the cholesteric liquid crystal layer composition on the support 12 is cured to fix the cholesteric liquid crystal phase. May be good.
The state in which the cholesteric liquid crystal phase is "fixed" is the most typical and preferable state in which the orientation of the liquid crystal compound which is the cholesteric liquid crystal phase is maintained. It is not limited to this, and specifically, in the temperature range of 0 to 50 ° C., and more severely, -30 to 70 ° C., the layer has no fluidity, and the layer is oriented by an external field or an external force. It shall mean a state in which the fixed orientation form can be kept stable without causing a change. In the present invention, as will be described later, it is preferable to fix the orientation state of the cholesteric liquid crystal phase by a curing reaction that proceeds by irradiation with ultraviolet rays.
In the layer in which the cholesteric liquid crystal phase is fixed, it is sufficient that the optical properties of the cholesteric liquid crystal phase are retained in the layer, and it is necessary that the composition in the layer finally exhibits liquid crystallinity. Absent.

The method of curing treatment is not particularly limited, and examples thereof include photo-curing treatment and thermosetting treatment. Among them, the light irradiation treatment is preferable, and the ultraviolet irradiation treatment is more preferable.
A light source such as an ultraviolet lamp is used for ultraviolet irradiation.
The amount of ultraviolet irradiation energy is not particularly limited, but is generally preferably about 0.1 to 0.8 J / cm ² . The time of irradiation with ultraviolet rays is not particularly limited, but may be appropriately determined from the viewpoints of both sufficient strength and productivity of the obtained layer.

After forming the flat cholesteric liquid crystal layer 16 having a flat structure in this way, the corrugated cholesteric liquid crystal layer 14 is formed on the flat cholesteric liquid crystal layer 16.

In the formation of the corrugated cholesteric liquid crystal layer 14, first, an upper layer composition for forming the corrugated cholesteric liquid crystal layer 14 containing the liquid crystal compound and the chiral agent as described above is prepared.
Next, the upper layer composition is applied onto (the surface) of the flat cholesteric liquid crystal layer 16. As the coating method, the same method as in the case of the flat cholesteric liquid crystal layer 16 is used.
Then, if necessary, the upper layer composition is dried and then heated to orient the liquid crystal compounds in the composition layer formed on the flat cholesteric liquid crystal layer 16 to obtain a cholesteric liquid crystal phase. The heating conditions are the same as above.

Here, when the corrugated cholesteric liquid crystal layer 14 is formed, the cholesteric liquid crystal layer composition is heated to bring the liquid crystal compound into the cholesteric liquid crystal phase, and then the spiral induction of the chiral agent contained in the cholesteric liquid crystal layer composition is induced. The composition is cooled or heated to form a cholesteric liquid crystal layer so as to improve the force. That is, the coating is applied so that the spiral inducing force (HTP: Helical Twisting Power) of the chiral agent contained in the cholesteric liquid crystal layer composition constituting the coating layer (composition layer) formed on the flat cholesteric liquid crystal layer 16 increases. The layer is cooled or heat treated.
By applying the cooling treatment and the heat treatment of the coating layer, the spiral inducing force of the chiral agent increases, the twist of the liquid crystal compound increases, and as a result, the orientation of the cholesteric liquid crystal phase (inclination of the spiral axis) changes. As a result, the bright and dark parts parallel to the support 12 are changed, and the corrugated cholesteric liquid crystal layer 14 having the bright and dark parts having a wavy structure (concave and convex structure) as shown in FIG. 3 (the cholesteric liquid crystal phase state). A layer of the composition) is formed.

When cooling the cholesteric liquid crystal layer composition, it is preferable to cool the composition so that the temperature of the composition is lowered by 30 ° C. or more because the diffuse reflectance of the corrugated cholesteric liquid crystal layer 14 is more excellent. Among them, in that the above effect is more excellent, it is preferable to cool the composition so that the temperature is lowered by 40 ° C. or higher, and it is more preferable to cool the composition so that the temperature is lowered by 50 ° C. or higher. The upper limit of the reduced temperature range of the cooling treatment is not particularly limited, but is usually about 70 ° C.
In other words, the cooling treatment is intended to cool the composition so that the temperature of the composition in the state of the cholesteric liquid crystal phase before cooling is T-30 ° C or lower.
The cooling method is not particularly limited, and examples thereof include a method in which the support 12 on which the composition is arranged is allowed to stand in an atmosphere having a predetermined temperature.

The cooling rate in the cooling process is not limited, but in order to suitably form the wavy structure of the bright and dark parts of the cholesteric liquid crystal phase, or further, the unevenness of the surface of the cholesteric liquid crystal layer, the cooling rate is set to some extent. It is preferable to set the speed.
Specifically, the maximum value of the cooling rate in the cooling treatment is preferably 1 ° C. or higher per second, and more preferably 2 ° C. or higher per second.

When the liquid crystal compound has a polymerizable group, the cholesteric liquid crystal layer composition may be cured after being cooled or heat-treated to fix the cholesteric liquid crystal phase. This curing treatment may be performed at the same time as the cooling treatment or the heat treatment, or may be performed after the cooling treatment or the heat treatment.
The curing treatment method is the same as in the case of the flat cholesteric liquid crystal layer.

In this way, the corrugated cholesteric liquid crystal layer 14 having a wavy structure can be formed, and a transparent screen 10a having the flat cholesteric liquid crystal layer 16Rr and the corrugated cholesteric liquid crystal layer 14Rr is produced on the support 12. be able to.

When the flat cholesteric liquid crystal layer 16 and the corrugated cholesteric liquid crystal layer 14 are provided in two or more layers, the same film formation may be repeated according to the number of cholesteric liquid crystal layers to be formed.

As described above, when the lower cholesteric liquid crystal layer has a wavy structure in the cross section, the upper cholesteric liquid crystal layer also follows the wavy structure of the lower cholesteric liquid crystal layer, and the bright and dark parts in the cross section are wavy. It may be a structure. Therefore, when a plurality of corrugated cholesteric liquid crystal layers 14 are formed, after the lower corrugated cholesteric liquid crystal layer 14 is formed by the above method, the upper corrugated cholesteric liquid crystal layer 14 is placed on the lower corrugated cholesteric liquid crystal layer 14. If the above is formed, the upper cholesteric liquid crystal layer also becomes a wavy cholesteric liquid crystal layer having a wavy structure in the bright and dark parts in the cross section.

Such a transparent screen of the present invention can be used as a screen for displaying a projected image and a half mirror. Further, by controlling the reflection band, it can also be used as a color filter or a filter for improving the color purity of the display light of the display (see, for example, Japanese Patent Application Laid-Open No. 2003-294948).
Further, the transparent screen can be used for various purposes such as a polarizing element, a reflective film, an antireflection film, a viewing angle compensating film, a holography, and an alignment film, which are constituent elements of an optical element.

The transparent screen of the present invention is particularly preferably used as a projection image display member such as a screen for displaying a projected image. Specifically, it is suitably used as a transparent screen of an image projection system.
That is, by the function of the cholesteric liquid crystal layer as described above, it is possible to form a projected image by reflecting the circularly polarized light of one of the senses at the wavelength showing selective reflection of the projected light. The projected image may be displayed on the surface of the transparent screen and visually recognized as such, or may be a virtual image that appears above the transparent screen when viewed from the observer.

Further, for example, by configuring the transparent screen of the present invention to have transparency with respect to light in the visible light region, a half mirror for projection display that can be used as a combiner of a head-up display can be obtained. The projected image display half mirror can visually display the image projected from the projector, and when the projected image display half mirror is observed from the same side on which the image is displayed, the opposite side is displayed. You can observe the information or landscape on the side at the same time.

Hereinafter, the features of the present invention will be described in more detail with reference to Examples and Comparative Examples. The materials, amounts used, ratios, treatment contents, treatment procedures, etc. shown in the following examples can be appropriately changed as long as they do not deviate from the gist of the present invention. Therefore, the scope of the present invention should not be construed as limited by the specific examples shown below.

[Preparation of liquid crystal compositions 1 to 3]
The components shown in Table 1 below were mixed to prepare liquid crystal compositions 1 to 3. The amount of each component is all parts by mass.

Rod-shaped liquid crystal compound 101

Rod-shaped liquid crystal compound 102

Rod-shaped liquid crystal compound 201

Rod-shaped liquid crystal compound 202

Aligning agent (1)

Aligning agent (2)

[Example 1]
As the support 12, a PET film (manufactured by FUJIFILM Corporation) subjected to a rubbing treatment was prepared.
The liquid crystal composition 1 was applied to the rubbing surface of the support 12 using the wire bar of # 8. The coating layer of the liquid crystal composition 1 was dried at room temperature for 10 seconds and then heated in an atmosphere of 95 ° C. for 1 minute to orient the liquid crystal compound. Then, the liquid crystal composition was cooled to 30 ° C. within 1 minute.
Then, the coating layer is irradiated with UV light (ultraviolet light) for 8 seconds at an output of 80% using a fusion D-bulb (lamp 90 mW / cm ² ) at 30 ° C., and a corrugated cholesteric liquid crystal is applied onto the support 12. Layer 14Rr was formed.

When the transmission spectrum of the corrugated cholesteric liquid crystal layer 14Rr was measured using a spectrophotometer UV-3100PC (manufactured by Shimadzu Corporation), it had a selective reflection peak having a center at a wavelength of 640 nm.
A part of the formed corrugated cholesteric liquid crystal layer 14Rr was peeled off, and a 10x objective lens was used with a shape measurement laser microscope VK-X200 (manufactured by KEYENCE), and the film thickness of the corrugated cholesteric liquid crystal layer 14Rr was 4 μm. Met.

Further, when the PET substrate having the cholesteric liquid crystal layer was set in the polarizing microscope and the cholesteric liquid crystal layer was observed so that the slow axis of the PET substrate coincided with the direction of the polarizer of the polarizing microscope, a wavy structure was formed. I confirmed it clearly.
In addition, it was confirmed by observing the cross section of the corrugated cholesteric liquid crystal layer by SEM observation that the layered structure of the cholesteric liquid crystal phase was corrugated (undulation structure).

Next, the liquid crystal composition 1 is applied onto the corrugated cholesteric liquid crystal layer 14Rr using the wire bar of # 6, and dried, heated, cooled and cured in the same manner as described above to perform the corrugated cholesteric liquid crystal layer 14Gr. Was formed.
The corrugated cholesteric liquid crystal layer 14Gr had a selective reflection peak centered at a wavelength of 530 nm.
The film thickness of the corrugated cholesteric liquid crystal layer 14 Gr was 3 μm.
Further, when the layered structure of the cholesteric liquid crystal phase was confirmed in the same manner as before, a wavy structure was confirmed.

Further, the liquid crystal composition 1 is applied onto the corrugated cholesteric liquid crystal layer 14Gr using the wire bar of # 4, and dried, heated, cooled and cured in the same manner as described above to obtain the corrugated cholesteric liquid crystal layer 14Br. Formed.
The corrugated cholesteric liquid crystal layer 14Br had a selective reflection peak centered at a wavelength of 445 nm.
The film thickness of the corrugated cholesteric liquid crystal layer 14Br was 2 μm.
Further, when the layered structure of the cholesteric liquid crystal phase was confirmed in the same manner as before, a wavy structure was confirmed.
The laminate having the three corrugated cholesteric liquid crystal layers thus obtained is referred to as "corrugated laminate A".

After orienting the liquid crystal compound at 95 ° C., the flat cholesteric liquid crystal layer 16Rr is formed in the same manner as the corrugated cholesteric liquid crystal layer 14Rr except that the liquid crystal composition is cooled from 95 ° C. to 30 ° C. over 5 minutes on a hot plate. Made.
A PET substrate having a cholesteric liquid crystal layer was set in a polarizing microscope so that the slow axis of the PET substrate of the same sample coincided with the direction of the polarizer of the polarizing microscope, and the cholesteric liquid crystal layer was observed. The structure (= undulation structure) could not be confirmed.
In addition, by observing the cross section of the laminate by SEM, it was observed that the layered structure of the cholesteric liquid crystal layer was horizontal to the support.

Next, a corrugated cholesteric liquid crystal is formed except that the liquid crystal compound is oriented on the flat cholesteric liquid crystal layer 16Rr at 95 ° C. and then the liquid crystal composition is cooled from 95 ° C. to 30 ° C. on a hot plate over 5 minutes. A flat cholesteric liquid crystal layer 16 Gr was produced in the same manner as the layer 14 Gr.
Further, the corrugated cholesteric liquid crystal layer except that the liquid crystal compound is oriented on the flat cholesteric liquid crystal layer 16 Gr at 95 ° C. and then the liquid crystal composition is cooled from 95 ° C. to 30 ° C. on a hot plate over 5 minutes. A flat cholesteric liquid crystal layer 16Br was produced in the same manner as 14Br.
The laminate having the three-layer flat cholesteric liquid crystal layer thus obtained is referred to as "flat laminate A".

The film thickness of the flat cholesteric liquid crystal layer 16Rr was 5 μm, the film thickness of the flat cholesteric liquid crystal layer 16Gr was 4 μm, and the film thickness of the flat cholesteric liquid crystal layer 16Br was 3 μm.
Further, when the layered structure of the cholesteric liquid crystal phase was confirmed in the same manner as before, the wavy structure could not be confirmed in any of the layers.

An optical adhesive (optical adhesive SK Dyne manufactured by Soken Chemical Co., Ltd.) was pasted on a PET sheet, and the "flat laminate A" was transferred onto the PET sheet to peel off the PET substrate on the flat laminate A side. Further, an optical adhesive layer (optical adhesive SK Dyne manufactured by Soken Chemical Co., Ltd.) is attached on the flat laminate A, and after transferring the "corrugated laminate A", the PET substrate on the corrugated laminate A side is peeled off. By doing so, a "transparent screen A" was obtained.

The combination of this "transparent screen A" and a laser projector (PicoPro manufactured by Celluon) was designated as Example 1-1. A circular polarizing plate was placed in front of the laser projector so that the light emitted to the transparent screen A was right-handed circularly polarized light. The central wavelength of the light source is 640 nm for the red light source, 530 nm for the green light source, and 445 nm for the blue light source.
Further, a combination of "transparent screen A" and a liquid crystal projector (EB-W28 manufactured by Seiko Epson Corporation) was set as Example 1-2. A circular polarizing plate was placed in front of the laser projector so that the light emitted to the transparent screen A was right-handed circularly polarized light.

[Example 2]
An optical adhesive was applied on the PET sheet, and the "flat laminate A" was transferred onto the PET sheet to peel off the PET substrate on the flat laminate A side. Further, an optical adhesive layer (optical adhesive SK Dyne manufactured by Soken Chemical Co., Ltd.) is pasted on the flat laminate A, and a commercially available λ / 2 plate (1/2 wavelength plate manufactured by Mitate Imaging Co., Ltd.) is bonded. did. Further, OCA was pasted on the λ / 2 plate, and the "flat laminate A" was transferred onto this, and the PET substrate on the flat laminate A side was peeled off. Subsequently, OCA was pasted on the flat laminate A, the "corrugated laminate A" was transferred, and then the PET substrate on the corrugated laminate A side was peeled off to obtain a "transparent screen B". ..

This "transparent screen B" was combined with a laser projector (PicoPro manufactured by Celluon).

[Comparative Example 1]
An optical adhesive (optical adhesive SK Dyne manufactured by Soken Chemical Co., Ltd.) is pasted on a PET sheet, and "flat laminate A" is transferred onto this, and the PET substrate on the flat laminate A side is peeled off. "Transparent screen C" was obtained.
The combination of this "transparent screen C" and a laser projector (PicoPro manufactured by Celluon) was designated as Comparative Example 1-1. A circular polarizing plate was placed in front of the laser projector so that the light emitted to the transparent screen C was right-handed circularly polarized light.
Further, the combination of "transparent screen C" and a liquid crystal projector (EB-W28 manufactured by Seiko Epson Corporation) was set as Comparative Example 1-2.

[Evaluation]
The following evaluations were made on the transparent screens produced in Examples and Comparative Examples.
<Visual evaluation>
As shown in FIG. 9, the laser projector 102, the transparent screen 10, and the opaque screen OS were installed, and an image was projected from the laser projector 102 to confirm whether the image formed on the transparent screen could be visually recognized. In the case of Example 1-1, Example 1-2, and Comparative Example 1-1, the circular polarizing plate 104 is arranged in front of the projector, and the light emitted to the transparent screen is right-handed circularly polarized light. I tried to be.

(Image formation on the screen (front))
It was confirmed whether the image irradiated from the projector and formed on the transparent screen could be visually recognized, and evaluated according to the following criteria.
A: The image can be clearly confirmed B: It is dark but the image can be confirmed C: The image formation cannot be confirmed

(Image formation on the screen (45 ° direction))
The direction of projection from the projector onto the transparent screen was set to 0 °, and it was confirmed whether the image formed on the transparent screen could be visually visually recognized from the position of 45 °.
A: The image can be clearly confirmed B: It is dark but the image can be confirmed C: The image formation cannot be confirmed

(Screen transparency)
I checked the transparent screen from 0 ° in a bright room and checked if the scenery behind the transparent screen could be seen.
A: Clearly visible B: Recognizing that there is something C: Invisible

(Reflection on opaque screen)
It was confirmed whether the image formed on the opaque screen could be visually recognized from between the transparent screen and the opaque screen.
A: Cannot be confirmed B: Dark but image is confirmed C: Image can be clearly confirmed

<Diffuse reflectivity evaluation>
The relative reflectance of the cholesteric liquid crystal layer with respect to the reference (white plate) was measured using the double beam measurement mode of GCMS-3B manufactured by Murakami Color Co., Ltd. The reflection spectra at 10 ° and 45 ° with respect to the light incident from the normal direction (0 °) to the sample were measured at 380 nm to 780 nm, and the Y value at this time was calculated.
Specifically, the incident light from the light source is irradiated from the normal direction of the surface of the sample (transparent screen or white plate), and the polar angles θ are 10 ° and 45 ° with respect to the normal direction of the surface of the sample. The reflected light was measured by a detector placed at the position, and the relative reflectance of the cholesteric liquid crystal layer with respect to the reference was measured and evaluated according to the following criteria.
A: 5 or more B: 3 or more and less than 5 C: less than 3

<Haze and total light transmittance>
The haze and total light transmittance of the produced transparent screen were measured. The haze and the total light transmittance were both measured using NDH4000 manufactured by Nippon Denshoku Kogyo Co., Ltd., the haze was measured in accordance with JIS K 7136, and the total light transmittance was measured in accordance with JIS K 7361.
The total light transmittance was evaluated according to the following criteria.
A: 50 or more B: 40% or more and less than 50% C: less than 40% In addition, haze was evaluated according to the following criteria.
A: 20% or less B: More than 20% 30% or less C: More than 30% The results are summarized in Table 2.

As shown in Table 2, all of the transparent screens of the present invention have a low haze, a high total light transmittance, a 45 ° relative reflection amount of 5 or more, and a good diffuse reflectance. That is, the laminate of the present invention has both good transparency and diffuse reflectivity.
Further, from the comparison between Examples 1-1 and 1-2, it can be seen that by combining the transparent screen of the present invention with a laser projector, reflection on an opaque screen arranged on the back side of the transparent screen can be suppressed.
From the above results, the effect of the present invention is clear.

10, 10a-10e Transparent screen 12 Support 14 Wave-shaped cholesteric liquid crystal layer 14Rr Wave-shaped cholesteric liquid crystal layer that has a selective reflection wavelength in the red light region and reflects right circular polarization 14Gr Has a selective reflection wavelength in the green light region Wave-shaped cholesteric liquid crystal layer that reflects right circular polarization 14Br Left-circular polarization that has selective reflection wavelength in the blue light region and reflects right circular polarization 14Rl has selective reflection wavelength in the red light region Wave-shaped cholesteric liquid crystal layer 14Gl that reflects selective reflection wavelength in the green light region Wave-shaped cholesteric liquid crystal layer that reflects left circular polarization 14Bl Wave that has selective reflection wavelength in the blue light region and reflects left circular polarization Type cholesteric liquid crystal layer 16 Flat cholesteric liquid crystal layer 16Rr Flat cholesteric liquid crystal layer that has a selective reflection wavelength in the red light region and reflects right circular polarization 16 Gr Has a selective reflection wavelength in the green light region and reflects right circular polarization Flat cholesteric liquid crystal layer 16Br Flat cholesteric liquid crystal layer that has a selective reflection wavelength in the blue light region and reflects right circular polarization 16Rl Flat cholesteric that has a selective reflection wavelength in the red light region and reflects left circular polarization Liquid crystal layer 16Gl Flat cholesteric liquid crystal layer having a selective reflection wavelength in the green light region and reflecting left circular polarization 16Bl Flat cholesteric liquid crystal layer having a selective reflection wavelength in the blue light region and reflecting left circular polarization 18 λ / 2 plates 100 Image projection system 102 Laser projector 104 Circular polarizing plate

Claims (17)

With the support
It has a plurality of cholesteric liquid crystal layers laminated on the support and formed by fixing the cholesteric liquid crystal phase.
Of the plurality of cholesteric liquid crystal layers, at least one layer is a corrugated cholesteric liquid crystal layer having a wavy structure in bright and dark areas derived from the cholesteric liquid crystal phase in cross section.
Of the plurality of cholesteric liquid crystal layers, at least one other layer is a flat cholesteric liquid crystal layer having a flat structure in which bright and dark portions derived from the cholesteric liquid crystal phase are parallel to the main surface of the support in cross section. Oh it is,
A transparent screen in which the thickness ratio of the corrugated cholesteric liquid crystal layer to the flat cholesteric liquid crystal layer is 1: 10 to 2: 1 . The transparent screen according to claim 1, wherein the selective reflection wavelength of at least one layer of the corrugated cholesteric liquid crystal layer is the same as the selective reflection wavelength of at least one layer of the flat cholesteric liquid crystal layer. Two or more corrugated cholesteric liquid crystal layers having different selective reflection wavelengths and
The transparent screen according to claim 1 or 2, further comprising two or more flat cholesteric liquid crystal layers having the same selective reflection wavelength as the selective reflection wavelength of each corrugated cholesteric liquid crystal layer. The transparent screen according to any one of claims 1 to 3, wherein the turning direction of the circularly polarized light reflected by the plurality of cholesteric liquid crystal layers is the same for all the cholesteric liquid crystal layers. It has two or more of the flat cholesteric liquid crystal layers having the same selective reflection wavelength and the same turning direction of reflected circularly polarized light.
The transparent screen according to any one of claims 1 to 4, which has a λ / 2 plate arranged between two or more flat cholesteric liquid crystal layers. It has two or more corrugated cholesteric liquid crystal layers having the same selective reflection wavelength and the same turning direction of reflected circularly polarized light.
The transparent screen according to any one of claims 1 to 5, which has a λ / 2 plate arranged between two or more corrugated cholesteric liquid crystal layers. The transparent screen according to any one of claims 1 to 3, further comprising two or more flat cholesteric liquid crystal layers having the same selective reflection wavelength but different turning directions of reflected circularly polarized light. The transparent screen according to any one of claims 1 to 7, further comprising two or more corrugated cholesteric liquid crystal layers having the same selective reflection wavelength but different turning directions of reflected circularly polarized light. The transparent screen according to any one of claims 1 to 8, wherein the total light transmittance of the support is 80% or more. The transparent screen according to any one of claims 1 to 9, wherein the forming surface of the cholesteric liquid crystal layer of the support is a flat surface. The transparent screen according to any one of claims 1 to 10, wherein the total light transmittance of the transparent screen is 50% or more. The amplitude of the wavy structure in the cross section of the corrugated cholesteric liquid crystal layer is the largest in the central region in the thickness direction, and gradually decreases toward the surface side and the support side, respectively, according to any one of claims 1 to 11. The transparent screen described in the section. The transparent screen according to any one of claims 1 to 12, wherein the surface of the corrugated cholesteric liquid crystal layer is flat. The transparent screen according to any one of claims 1 to 13 .
An image projection system including a laser projector that irradiates the transparent screen with light. The image projection system according to claim 14 , wherein the selective reflection wavelength of at least one layer of the cholesteric liquid crystal layer included in the transparent screen is in the range of ± 20 nm of the center wavelength of the light source of the laser projector. The image projection system according to claim 14 or 15 , wherein the light emitted by the laser projector is circularly polarized light. The image projection system according to claim 16 , wherein the turning direction of the circular polarization reflected by at least one of the cholesteric liquid crystal layers included in the transparent screen coincides with the turning direction of the circular polarization irradiated by the laser projector.