JP2019035838A - Structure - Google Patents

Abstract

To provide a structure having a cholesteric liquid crystal layer and capable of achieving both of low haze properties and diffuse reflectivity.SOLUTION: The structure has a cholesteric liquid crystal layer formed by fixing a cholesteric liquid crystal phase therein. The cholesteric liquid crystal phase includes particles each having a particle size smaller than the spiral pitch of the cholesteric liquid crystal phase. Further, in the cholesteric liquid crystal layer, a bright portion and dark portion derived from the cholesteric liquid crystal phase are wavy in a cross section.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a structure having a layer formed by fixing a cholesteric liquid crystal phase.

A cholesteric liquid crystal layer formed by fixing a cholesteric liquid crystal phase is a liquid crystal layer having a structure in which molecules are aligned in a spiral shape. The cholesteric liquid crystal layer selectively reflects right circularly polarized light or left circularly polarized light in a wavelength range corresponding to the helical pitch (one turn of the spiral) on a plane orthogonal to the helical axis of the molecule.
Therefore, the cholesteric liquid crystal layer has been developed for various uses, and for example, a transparent or translucent projection screen, a reflector and a paint have been proposed.

A normal cholesteric liquid crystal layer has specular reflectivity. However, particularly in applications such as a projection screen, it is advantageous to have diffuse reflectivity (non-specular reflectivity) in terms of improving visibility (viewing angle characteristics).
On the other hand, Patent Document 1 includes a cholesteric liquid crystal pigment that selectively reflects light of a specific polarization component and a cholesteric liquid crystal binder that selectively diffuses and reflects light of a specific polarization component. A projection screen having a diffusely reflective cholesteric liquid crystal layer is described. In Patent Document 1, the cholesteric liquid crystal layer has a cholesteric liquid crystal pigment, and in the cholesteric liquid crystal binder, the cholesteric liquid crystal layer has a diffuse reflection property due to variations in the direction of the spiral axis of the cholesteric liquid crystal phase.

  Patent Document 2 discloses a cholesteric liquid crystal display device having a cholesteric liquid crystal layer, in which the cholesteric liquid crystal layer is three-dimensionally cross-linked and has an average particle diameter of 400 to 1000 nm. Containing backscattering characteristics to the cholesteric liquid crystal layer by containing fine particles having different refractive indexes from those of the cholesteric liquid crystal layer forming material having an average particle size larger than the helical pitch of the cholesteric liquid crystal phase and less than 400 nm. A cholesteric liquid crystal display device is described.

JP 2005-99158 A Japanese Patent Laid-Open No. 2005-202093

As described in Patent Documents 1 and 2, by adding particles to the cholesteric liquid crystal layer, diffuse reflectance can be imparted to the cholesteric liquid crystal layer.
However, when particles are added to the cholesteric liquid crystal layer, the haze of the cholesteric liquid crystal layer is remarkably increased, and there is a problem that it cannot be used for applications such as a projection screen.

  An object of the present invention is to provide a structure having both low haze and diffuse reflectivity in a structure having a cholesteric liquid crystal layer.

  The inventor has conducted intensive studies on the above problems, and as a result, the cholesteric liquid crystal layer has a wavy structure in the bright and dark portions derived from the cholesteric liquid crystal phase in the cross section in the thickness direction, and the cholesteric liquid crystal phase. It has been found that by containing particles having a diameter smaller than that of the helical pitch, both low haze and diffuse reflectivity can be obtained.

That is, this invention solves a subject with the following structures.
[1] A structure having a cholesteric liquid crystal layer formed by fixing a cholesteric liquid crystal phase,
A structure in which the cholesteric liquid crystal layer includes particles having a particle size smaller than the helical pitch of the cholesteric liquid crystal phase, and the bright and dark portions derived from the cholesteric liquid crystal phase are wavy in the cross section in the thickness direction. body.
[2] The structure according to [1], wherein the cholesteric liquid crystal layer is a three-dimensionally crosslinked polymer material.
[3] The structure according to [1] or [2], wherein the content of particles in the cholesteric liquid crystal layer is 0.01 to 2% by mass.
[4] The structure according to any one of [1] to [3], wherein the cholesteric liquid crystal phase has a helical pitch of 220 to 2000 nm.
[5] The ratio according to any one of [1] to [4], wherein the ratio of the average particle diameter of the particles to the helical pitch of the cholesteric liquid crystal phase is 0.8 or less in terms of the average particle diameter / spiral pitch. Structure.
[6] The ratio of the average particle diameter of the particles to the wave period formed by the bright and dark parts derived from the cholesteric liquid crystal phase in the cholesteric liquid crystal layer is 0.2 or less in terms of the ratio of the average particle diameter / wave period. The structure according to any one of [1] to [5].

  According to the present invention, in a structure having a cholesteric liquid crystal layer, a structure having both low haze and diffuse reflectivity can be provided.

It is sectional drawing which shows notionally an example of the structure of this invention. It is a conceptual diagram for demonstrating reflection of a cholesteric liquid crystal layer. It is a conceptual diagram for demonstrating reflection of a cholesteric liquid crystal layer. It is sectional drawing which shows notionally another example of the structure of this invention. It is the elements on larger scale of FIG.

Hereinafter, the present invention will be described in detail. In the present specification, a numerical range represented by using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.
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, “(Meth) acryl” is a notation representing both acrylic and methacrylic.

FIG. 1 conceptually shows a cross section of the structure of the present invention. FIG. 1 is a diagram conceptually showing, for example, a state where a cross section of the structure of the present invention is observed with a scanning electron microscope (SEM) (the same applies to FIGS. 2 and 3 described later).
A structure 10 shown in FIG. 1 includes a substrate 12 and a cholesteric liquid crystal layer 14 formed on one surface of the substrate 12. In the following description, the substrate 12 side of the structure 10 is also referred to as “lower” and the cholesteric liquid crystal layer 14 side is also referred to as “upper”.

The cholesteric liquid crystal layer 14 is a layer formed by fixing a cholesteric liquid crystal phase.
In the layer formed by fixing the cholesteric liquid crystal phase, the liquid crystal molecules are oriented in a spiral shape, have wavelength selectivity for reflection, and only the right circularly polarized light in a predetermined wavelength region (wavelength region) or the left Only circularly polarized light is selectively reflected, and other light is transmitted.

In the structure of the present invention, the cholesteric liquid crystal layer may reflect right circularly polarized light or reflect left circularly polarized light. Alternatively, the structure of the present invention may have both a cholesteric liquid crystal layer that reflects right circularly polarized light and a cholesteric liquid crystal layer that reflects left circularly polarized light.
In the structure of the present invention, there is no limitation on the wavelength range in which the cholesteric liquid crystal layer reflects and the selective reflection center wavelength of the cholesteric liquid crystal layer. Therefore, the cholesteric liquid crystal layer may be a cholesteric liquid crystal layer that selectively reflects infrared light, a cholesteric liquid crystal layer that selectively reflects red light, or a cholesteric liquid crystal layer that selectively reflects green light. It may be a cholesteric liquid crystal layer that selectively reflects or a cholesteric liquid crystal layer that selectively reflects ultraviolet rays.
Further, the structure of the present invention is not limited in the layer structure. Accordingly, the structure of the present invention may have, for example, a structure having only one cholesteric liquid crystal layer that selectively reflects green light, and selectively reflects green light and a cholesteric liquid crystal layer that selectively reflects red light. A cholesteric liquid crystal layer that selectively reflects red light, a cholesteric liquid crystal layer that selectively reflects green light, and a cholesteric liquid crystal layer that selectively reflects blue light. A cholesteric liquid crystal layer that selectively reflects infrared light, a cholesteric liquid crystal layer that selectively reflects red light, a cholesteric liquid crystal layer that selectively reflects green light, and blue light are selectively reflected. A four-layer structure having a cholesteric liquid crystal layer or a structure having five or more cholesteric liquid crystal layers may be used.

As described above, the cholesteric liquid crystal layer 14 is a layer formed by fixing a cholesteric liquid crystal phase.
Therefore, the cholesteric liquid crystal layer 14 has a bright portion 16 and a dark portion 18 in the thickness direction (vertical direction in FIG. 1) in the cross section (thickness direction cross section) observed with the SEM. Alternating stripes are observed. That is, in the cross section of the cholesteric liquid crystal layer 14 in which the cholesteric liquid crystal phase is fixed, a layered structure in which the bright portions 16 and the dark portions 18 are alternately stacked is observed. The normal line of each line of the striped pattern is the spiral axis direction of the cholesteric liquid crystal phase.
Here, in the structure 10 of the illustrated example, the formation surface of the cholesteric liquid crystal layer 14 on the substrate 12 is a flat surface, but the bright portion 16 and the dark portion 18 in the cross section of the cholesteric liquid crystal layer 14 formed on the substrate 12 are periodic. It has a typical wavy structure (uneven structure).
In other words, in the present invention, the cholesteric liquid crystal layer 14 is a layer having a cholesteric liquid crystal structure and a structure in which the angle formed by the spiral axis and the surface of the substrate 12 changes periodically. In other words, the cholesteric liquid crystal layer 14 has a cholesteric liquid crystal structure, and the cholesteric liquid crystal structure gives a stripe pattern of the bright part 16 and the dark part 18 in the cross-sectional view observed by the SEM. This is a layer in which the angle formed between the normal line and the surface of the substrate 12 changes periodically.

In the cholesteric liquid crystal layer 14, two repetitions of the bright part 16 and the dark part 18 (two bright parts and two dark parts) correspond to one spiral (one spiral winding). From this, the helical pitch of the cholesteric liquid crystal layer can be measured from the SEM sectional view.
In the structure 10 of the present invention, the cholesteric liquid crystal layer 14 contains particles 20 having a particle diameter (particle diameter) smaller than one helical pitch (spiral pitch). This will be described in detail later.

FIG. 2 conceptually shows a cross section of a general cholesteric layer.
As described above, as shown in FIG. 2, in the cross section of the cholesteric liquid crystal layer 50a formed on the substrate 12, a stripe pattern of the bright portion 16 and the dark portion 18 is usually observed.
Generally, the stripe pattern (layered structure) of the bright part 16 and the dark part 18 is formed so as to be parallel to the surface of the substrate 12 that is the formation surface, as shown in FIG. The cholesteric liquid crystal layer exhibits specular reflectivity on a plane orthogonal to the spiral axis. Therefore, in such an embodiment, the cholesteric liquid crystal layer 50a in which the cholesteric liquid crystal phase is fixed exhibits specular reflectivity. That is, when light is incident from the normal direction of the cholesteric liquid crystal layer 50a, the light is reflected in the normal direction, but the light is hardly reflected in the oblique direction, and the diffuse reflectivity is poor (arrow in FIG. 2). reference).

On the other hand, when the formation surface (substrate 12) is a flat surface and the bright portion 16 and the dark portion 18 have a wave-like structure (undulation structure) like the cholesteric liquid crystal layer 50b conceptually shown in cross section in FIG. In this case, when light is incident on the cholesteric liquid crystal layer 50b having a wavy structure from the normal direction of the cholesteric liquid crystal layer 50b, there is a region in which the helical axis of the liquid crystal compound is inclined, and thus a part of the incident light Is reflected in an oblique direction (see the arrow in FIG. 3).
That is, in the cholesteric liquid crystal layer formed by fixing the cholesteric liquid crystal phase, the bright portion 16 and the dark portion 18 have a wave-like structure, so that a cholesteric liquid crystal layer having high diffuse reflection can be realized. Further, the diffuse reflection property becomes better as the unevenness of the wave-like structure of the bright part 16 and the dark part 18 is larger.
In the following description, the “bright structure of the bright part and the dark part” of the cholesteric liquid crystal layer is also simply referred to as “wave structure”.

As will be described later, as an example, the cholesteric liquid crystal layer having a wavy structure is formed by applying a composition containing a liquid crystal compound and a chiral agent to the surface to be formed, and aligning the liquid crystal compound in the cholesteric liquid crystal phase by heating the composition. Then, it can be formed by cooling the composition and fixing the cholesteric liquid crystal phase by ultraviolet irradiation or the like.
As described above, when the structure has a plurality of cholesteric layers, when the cholesteric liquid crystal layer is formed on the cholesteric liquid crystal layer having the wave structure, the structure follows the wave structure of the lower cholesteric liquid crystal layer (cholesteric liquid crystal layer). Following the wave-like structure of the liquid crystal layer), the upper cholesteric liquid crystal layer also has the same wave-like structure.
Furthermore, the larger the irregularity of the wave structure of the lower cholesteric liquid crystal layer, the larger the irregularity of the wave structure of the upper cholesteric liquid crystal layer. Note that the fact that the corrugated structure of the cholesteric liquid crystal layer is large indicates that the wave height is high and the wave period is short.

In the structure 10 of the present invention, the wave structure in the cross section of each cholesteric liquid crystal layer 14 has a substantially uniform wave period, but the wave height may vary.
For example, the height of the wave may be the highest in the central region in the thickness direction of the cholesteric liquid crystal layer 14, and may gradually decrease toward the upper side (surface side) in the thickness direction and the substrate 12 side. That is, the amplitude of the wavy structure in the cross section of the cholesteric liquid crystal layer 14 may be configured such that the central region in the thickness direction is the largest and gradually decreases toward the surface side and the substrate 12 side.
Alternatively, it may be a structure having a wave having a uniform height throughout the thickness direction, such as a wave-like structure of the cholesteric liquid crystal layer 50b shown in FIG.

In the structure 10 of the illustrated example, the surface 24 (interface with the air (upper layer)) of the cholesteric liquid crystal layer 14 may be planar or may have a concavo-convex structure as shown in FIG.
In the cholesteric liquid crystal layer 14 having irregularities on the surface 24, the wave height of the wavy structure in the cross section of the cholesteric liquid crystal layer 14 is larger than that of the cholesteric liquid crystal layer having a flat surface.
Therefore, the cholesteric liquid crystal layer 14 having irregularities on the surface 24 can obtain higher diffuse reflectance.

When the surface 24 of the cholesteric liquid crystal layer 14 has a concavo-convex structure, this concavo-convex structure is generally periodic (substantially periodic), and as shown in FIG. This is the opposite of the wavy structure of the bright and dark areas.
Specifically, the unevenness of the surface 24 of the cholesteric liquid crystal layer 14 has a half (substantially half) phase shift with respect to the corrugated structure of the cross section. Therefore, in the surface direction of the substrate 12, the position of the convex portion of the corrugated liquid crystal layer 14 in the cross-section of the cholesteric liquid crystal layer 14 becomes the position of the concave / convex concave portion of the surface 24 of the cholesteric liquid crystal layer 14. Is the position of the convex and concave portions of the surface 24 of the cholesteric liquid crystal layer 14.

Further, as shown in FIG. 1, the cholesteric liquid crystal layer 14 basically has a period C1 of a wave-like structure in a cross section and a period C2 of irregularities on the surface 24. That is, in the cholesteric liquid crystal layer 14, the period of the wavy structure in the cross section and the period of the irregularities on the surface 24 are equal.
As shown in FIG. 1, the period C <b> 1 is the interval between the vertices of the wave of the dark portion 18 closest to the surface 24 of the cholesteric liquid crystal layer 14, and the period C <b> 2 is the apex of the convex portion on the surface 24 of the cholesteric liquid crystal layer 14. Is the interval.
In the present invention, the period C1 and the period C2 are equal not only when the period C1 and the period C2 completely match, but also by “[(C1-C2) / C1] × 100”. This includes cases where the difference in period is ± 30% or less.

As described above, in order to obtain good high diffuse reflectance in the cholesteric liquid crystal layer 14, it is preferable to narrow the period C1 of the wavy structure and increase (high) the wave of the wavy structure in the cross section. . Here, the uneven state of the surface 24 of the cholesteric liquid crystal layer 14 is greatly influenced by the wavy structure of the cross section. Accordingly, in order to obtain good diffuse reflectance in the cholesteric liquid crystal layer 14, it is preferable to narrow the period C2 of the unevenness on the surface and increase (deep) the height h of the unevenness. In particular, the higher the unevenness height h, the higher the diffuse reflectance.
However, when the period C2 of the irregularities on the surface 24 of the cholesteric liquid crystal layer 14, that is, the period C1 of the corrugated structure of the cross section is narrowed, the height h of the irregularities tends to be lowered. On the contrary, when the height h of the unevenness of the surface 24 is increased, the period C2 of the unevenness, that is, the period C1 of the wavy structure tends to be narrowed.
Considering this point, the period C1 of the wave-like structure of the cholesteric liquid crystal layer 14 is preferably 0.5 to 10 μm, and more preferably 1 to 6 μm. In the cholesteric liquid crystal layer 14, the period C2 of the irregularities on the surface 24 and the period C1 of the corrugated structure in the cross section are basically the same as described above.
Moreover, 1-500 nm is preferable and, as for the height h of the unevenness | corrugation of the surface 24 of the cholesteric liquid crystal layer 14, 5-300 nm is more preferable.

  The cholesteric liquid crystal layer 14 having a concavo-convex structure on the surface 24 performs at least one of selection of a chiral agent and / or an alignment control agent and selection of a heat treatment or cooling treatment condition in a manufacturing method described later. Can be formed.

In the structure 10 of the present invention, the wavy structure in the cross section of the cholesteric liquid crystal layer 14 (the wavy structure of the bright portion 16 and the dark portion 18) is not limited to the horizontal direction of FIG. A similar wave-like structure is formed even in the cross section. That is, the wave-like structure of the cholesteric liquid crystal layer 14 is two-dimensionally formed in the plane direction of the cholesteric liquid crystal layer 14, and the cholesteric liquid crystal layer 14 has a wave-like structure in cross sections in all directions.
However, the present invention is not limited to this, and the cholesteric liquid crystal layer 14 may have a wave-like structure formed so that continuous waves travel only in one direction in the cross section. However, in terms of diffuse reflectivity, the cholesteric liquid crystal layer 14 preferably has a wave-like structure in cross sections in all directions as described above.
The same applies to the unevenness of the surface of the cholesteric liquid crystal layer 14 in this regard.

In the structure 10 of the present invention, the cholesteric liquid crystal layer 14 is formed by fixing a cholesteric liquid crystal phase, the cholesteric liquid crystal layer 14 has a wave-like structure (bright portion 16 and dark portion 18) in cross section, and It contains particles 20 having a particle size smaller than the helical pitch (1 helical pitch) of the cholesteric liquid crystal phase.
By having such a structure, the structure 10 of the present invention achieves both low haze and good diffuse reflectivity (light diffusibility).

As shown in Patent Documents 1 and 2, in a structure having a cholesteric liquid crystal layer formed by fixing a cholesteric liquid crystal phase, diffuse reflectance can be improved by adding particles to the cholesteric liquid crystal layer.
However, in the conventional structure, the particle size of the particles added to the cholesteric liquid crystal layer is large, and as shown in Patent Document 2, particles having a particle size larger than the helical pitch of the cholesteric liquid crystal phase are added. When particles having a large particle size are added, the diffuse reflection property is improved, but the haze is remarkably improved, and it cannot be used for applications requiring transparency, such as a transparent projection screen.

On the other hand, in the present invention, particles 20 having a particle diameter smaller than the helical pitch of the cholesteric liquid crystal phase (spiral 1 pitch) are added. By reducing the particle size of the particles 20, the effect of significantly reducing the increase in haze due to the addition of the particles and the effect of reducing the haze value itself can be obtained.
That is, the structure 10 of the present invention greatly improves the haze resulting from the addition of the particles 20 by adding the particles 20 having a particle size smaller than the helical pitch to the cholesteric liquid crystal layer 14 having a wavy structure. In addition, a high diffuse reflectivity is realized by a synergistic effect of the wave-like structure of the cholesteric liquid crystal layer 14 and the cholesteric liquid crystal layer 14 having the particles 20. ).

There is no restriction | limiting in the particle size (diameter) of the particle | grains 20, What is necessary is just to be smaller than the helical pitch of a cholesteric liquid crystal phase. The average particle diameter of the particles 20 is preferably 0.001 to 0.8 times the helical pitch, more preferably 0.01 to 0.6 times, and even more preferably 0.02 to 0.5 times.
By making the average particle diameter of the particles 20 0.001 times or more of the helical pitch, it is preferable in that the diffuse reflectivity can be suitably improved. By making the average particle diameter of the particles 20 0.8 times or less of the helical pitch, it is preferable in that the haze can be suitably suppressed.
Examples of a method for measuring the average particle diameter of the particles 20 include a laser diffraction / scattering method, a dynamic light scattering method, and a BET (Brunauer Emmett Telle) method. Moreover, when using a commercial item as the particle | grains 20, you may utilize a catalog value etc. for the average particle diameter of the particle | grains 20. FIG.

In the structure 10 of the present invention, the content of the particles 20 in the cholesteric liquid crystal layer 14 is not limited, and is appropriately determined according to the particle size of the particles 20, the required haze, the required diffuse reflectance, and the like. , You can set.
The content of the particles 20 in the cholesteric liquid crystal layer 14 is preferably 0.01 to 2% by mass, more preferably 0.01 to 1% by mass, further preferably 0.02 to 0.7% by mass, and 0.05 to 0.5% by mass is particularly preferred.
By setting the content of the particles 20 in the cholesteric liquid crystal layer 14 to 0.01% by mass or more, it is preferable in terms of obtaining good diffuse reflectance. Further, the content of the particles 20 in the cholesteric liquid crystal layer 14 is preferably 2% by mass or less from the viewpoints of being able to suppress haze and maintaining high transparency.

In the structure 10 of the present invention, the period C1 of the wavy structure in the cholesteric liquid crystal layer 14 is strongly influenced by the helical pitch of the cholesteric liquid crystal phase. Generally, the shorter the helical pitch of the cholesteric liquid crystal phase, the shorter the period C1 of the wavy structure. Becomes smaller.
Accordingly, the smaller the period C1 of the wavy structure, the shorter the helical pitch, that is, the smaller the particle size of the particles 20 that can be added.

There is no limitation on the relationship between the average particle diameter of the particles 20 and the helical pitch of the cholesteric liquid crystal phase in the cholesteric liquid crystal layer 14.
The average particle diameter of the particles 20 and the helical pitch of the cholesteric liquid crystal phase are preferably 0.8 or less, more preferably 0.5 or less, and further preferably 0.2 or less, in the ratio of “average particle diameter / spiral pitch”. preferable.
By setting the ratio of “average particle diameter / spiral pitch” to 0.8 or less, it is preferable in that haze can be further suppressed, and diffuse reflectance can be improved while suppressing haze.
The ratio of “average particle diameter / spiral pitch” is preferably 0.01 or more.

The relationship between the average particle diameter of the particles 20 and the period C1 of the wavy structure in the cholesteric liquid crystal layer 14 is not limited.
The average particle diameter of the particles 20 and the period C1 of the wavy structure is a ratio of “average particle diameter / period C1”, preferably 0.2 or less, more preferably 0.1 or less, further preferably 0.05 or less, 0.02 or less is particularly preferable.
By setting the ratio of “average particle diameter / period C1” to 0.2 or less, it is preferable in that haze can be further suppressed.
The ratio of “average particle diameter / period C1” is preferably 0.001 or more.

There is no restriction | limiting in the formation material of the particle | grain 20, Various particle | grains can be utilized.
Examples include oxide-based nanoparticles (such as silica sol, zirconium oxide, zinc oxide, titanium oxide, titanium oxynitride and ITO (Indium Tin Oxide)), nanodiamonds, silver nanoparticles, and polymer-based nanoparticles (polystyrene, acrylic). Resin and melamine) and the like.
Moreover, various commercially available products can be suitably used for the particles 20.

The thickness of the cholesteric liquid crystal layer 14 is not limited, and the thickness satisfying the diffuse reflectance required for the cholesteric liquid crystal layer 14 is determined by the size in the surface direction of the cholesteric liquid crystal layer 14, the material for forming the cholesteric liquid crystal layer 14, It may be set appropriately according to the above.
The thickness of the cholesteric liquid crystal layer 14 is preferably 0.3 to 20 μm, and more preferably 0.5 to 10 μm. By setting the thickness of the cholesteric liquid crystal layer 14 to 0.3 μm or more, the cholesteric liquid crystal layer 14 having a sufficient thickness can provide good diffuse reflectance. Further, by setting the thickness of the cholesteric liquid crystal layer 14 to 20 μm or less, the cholesteric liquid crystal layer 14 can be prevented from becoming unnecessarily thick, and for example, a projection image display member described later can be thinned.
As described above, when a plurality of reflective layers are provided on the substrate 12, the thickness per layer is preferably within this range. The thickness of the cholesteric liquid crystal layer having no irregularities on the surface 24 is also preferably within this range.

As described above, the structure 10 is obtained by forming the cholesteric liquid crystal layer 14 on the substrate 12, in which the bright portions 16 and the dark portions 18 in the cross section have a wave-like structure and contain the particles 20.
In the structure 10, the substrate 12 is a plate-like material for supporting the cholesteric liquid crystal layer 14 (composition forming the cholesteric liquid crystal layer 14).
The substrate 12 preferably has no color (color) (that is, an achromatic color) and has a total light transmittance of 70% or more. That is, the substrate 12 is preferably colorless and transparent. Further, the total light transmittance of the substrate 12 is more preferably 80% or more, and further preferably 90% or more.
In the present invention, the total light transmittance may be measured in accordance with JIS K 7361 using a commercially available measuring device such as NDH5000 or SH-4000 manufactured by Nippon Denshoku Industries Co., Ltd.

The material constituting the substrate 12 is not particularly limited, and examples thereof include cellulose polymers, polycarbonate polymers, polyester polymers, (meth) acrylic polymers, styrene polymers, polyolefin polymers, vinyl chloride polymers, amide polymers, Various resin materials such as an imide polymer, a sulfone polymer, a polyether sulfone polymer, and a polyether ether ketone polymer are listed.
The substrate 12 may contain various additives such as UV (ultraviolet) absorbers, matting agent fine particles, plasticizers, deterioration inhibitors, and release agents. Further, the substrate 12 may have a layer such as an alignment layer on the surface.
The substrate is preferably low birefringence in the visible light region. For example, the retardation of the substrate at a wavelength of 550 nm is preferably 50 nm or less, and more preferably 20 nm or less.

The thickness of the substrate 12 is not particularly limited, but is preferably 10 to 200 μm, more preferably 20 to 100 μm, from the viewpoints of thinning and handling properties.
As described above, in the structure 10 of the illustrated example, the cholesteric liquid crystal layer 14 has a wave-like structure, but the surface on which the cholesteric liquid crystal layer 14 is formed on the substrate 12 is not a concavo-convex structure or a wave-like structure. It is.

As described above, the cholesteric liquid crystal layer 14 in which the bright portion 16 and the dark portion 18 in the cross section have a wave-like structure and contains the particles 20 is provided on the substrate 12.
As described above, the cholesteric liquid crystal layer 14 is a layer formed by fixing a cholesteric liquid crystal phase, has wavelength selectivity for reflection, and reflects left circularly polarized light or right circularly polarized light.

The selective reflection center wavelength (selective reflection center wavelength λ) of the cholesteric liquid crystal layer 14 in which the cholesteric liquid crystal phase is fixed depends on the pitch P (= spiral period) of the helical structure in the cholesteric liquid crystal phase, and the cholesteric liquid crystal layer 14 (cholesteric liquid crystal layer 14). According to the relationship between the average refractive index n of the liquid crystal phase) and λ = n × P.
Here, the central wavelength λ of selective reflection of the cholesteric liquid crystal layer 14 means a wavelength at the center of gravity position of the reflection peak of the circularly polarized reflection spectrum measured from the normal direction of the cholesteric liquid crystal layer 14. As can be seen from the above equation, the center wavelength of selective reflection can be adjusted by adjusting the pitch of the helical structure. That is, by adjusting the n value and the P value, for example, to selectively reflect either the right circularly polarized light or the left circularly polarized light with respect to the blue light, the center wavelength λ is adjusted, and an apparent selection is made. The central wavelength of reflection can be in the 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 circularly polarized reflection spectrum of the cholesteric liquid crystal layer 14 measured from the observation direction in practical use (when used as a projection image display member). Means. Since the pitch of the cholesteric liquid crystal phase depends on the kind of chiral agent used together with the liquid crystal compound or the concentration of the chiral agent, the desired pitch can be obtained by adjusting these.

In addition, although there is no restriction | limiting in the pitch P of the helical structure in a cholesteric liquid crystal phase, 220-2000 nm is preferable and 240-1500 nm is more preferable.
That is, in the structure 10 of the present invention, the cholesteric liquid crystal layer 14 preferably selectively reflects circularly polarized light in a predetermined wavelength region in the range from the ultraviolet wavelength region to the infrared wavelength region.

The reflected light of the cholesteric liquid crystal layer 14 formed by fixing the cholesteric liquid crystal phase is circularly polarized light. That is, the structure 10 of the present invention reflects circularly polarized light. Whether the reflected light is right-handed circularly polarized light or left-handed circularly polarized light depends on the twist direction of the cholesteric liquid crystal phase. The selective reflection of circularly polarized light by the cholesteric liquid crystal phase reflects right circularly polarized light when the twist direction of the spiral of the cholesteric liquid crystal phase is right, and reflects left circularly polarized light when the twist direction of the spiral is left.
The direction of rotation of the cholesteric liquid crystal phase can be adjusted by the type of liquid crystal compound forming the cholesteric liquid crystal layer 14 or the type of chiral agent added.

  The method of measuring the twist direction (sense) or pitch of the spiral is described in “Introduction to Liquid Crystal Chemistry Experiments” edited by the Japanese Liquid Crystal Society, Sigma Publishing 2007, page 46, and “Liquid Crystal Handbook”, Liquid Crystal Handbook Editorial Committee Maruzen, page 196. The method can be used.

  The cholesteric liquid crystal layer 14 is a layer formed by fixing a cholesteric liquid crystal phase. For example, the cholesteric liquid crystal layer 14 is prepared by preparing a composition containing a liquid crystal compound, a chiral agent, and the above-described particles 20, applying and drying the composition, and curing the composition as necessary. Then, it can be formed by fixing the cholesteric liquid crystal phase. The cholesteric liquid crystal layer 14 is particularly preferably formed of a polymer material that is three-dimensionally crosslinked by polymerizing a liquid crystal compound having two or more polymerizable groups.

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

The liquid crystal compound may have a polymerizable group. The kind of the polymerizable group is not particularly limited, and a functional group capable of addition polymerization reaction is preferable, and a polymerizable ethylenically unsaturated group or a ring polymerizable group is more preferable. More specifically, the polymerizable group is preferably a (meth) acryloyl group, a vinyl group, a styryl group, an allyl group, an epoxy group, or an oxetane group, and more preferably a (meth) acryloyl group.
The number of polymerizable groups is not particularly limited, but is preferably 2 or more. The upper limit is not particularly limited, but is often 8 or less.

As the liquid crystal compound, a liquid crystal compound represented by the following formula (I) is preferable in that the diffuse reflectance of the cholesteric liquid crystal layer 14 is more excellent.
Among these, the number obtained by dividing the number of trans-1,4-cyclohexylene groups optionally having a substituent represented by A by m is mc in that the diffuse reflectance of the cholesteric liquid crystal layer 14 is more excellent. The liquid crystal compound satisfying mc> 0.1 is preferable, and the liquid crystal compound satisfying 0.4 ≦ mc ≦ 0.8 is more preferable.
The mc is a number represented by the following calculation formula.
mc = (number of trans-1,4-cyclohexylene groups optionally having a substituent represented by A) / m

Where
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. 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) From —, —C (═O) NH—, —CH═N—, —N═CH—, —CH═CH—C (═O) O—, and —OC (═O) —CH═CH—. A linking group selected from the group consisting of
m represents an integer of 3 to 12,
Sp ¹ and Sp ² are each 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. When two or more —CH ₂ — are —O—, —S—, —NH—, —N (CH ₃ ) —, —C (═O) —, —OC (═O) —, or —C (═O ) Represents 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), One of Q ¹ and Q ² represents 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 this 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 as 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 still more preferably an integer of 3 to 5.

In the formula (I), the substituent that the phenylene group and trans-1,4-cyclohexylene group may have is not particularly limited, and examples thereof include an alkyl group, a cycloalkyl group, an alkoxy group, and an alkyl ether. And a substituent selected from the group consisting of a group composed of a group, an amide group, an amino group, a halogen atom, and 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 trans-1,4-cyclohexylene group may have 1 to 4 substituents. When it has two or more substituents, the two or more substituents may be the same or different from each other.

  In this specification, the alkyl group may be linear or branched. 1-30 are preferable, as for carbon number of an alkyl group, 1-10 are more preferable, and 1-6 are more preferable. Examples of the alkyl group include a methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, isopentyl group, neopentyl group, Examples include 1,1-dimethylpropyl group, n-hexyl group, isohexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, and dodecyl group. The description of the alkyl group in the alkoxy group is the same as the description regarding the alkyl group. In the present specification, specific examples of the alkylene group referred to as an alkylene group include a divalent group obtained by removing one arbitrary hydrogen atom in each of the above examples of the 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 cycloalkyl group preferably has 3 or more carbon atoms, more preferably 5 or more, more preferably 20 or less, still more preferably 10 or less, still more 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, and a cyclooctyl group.

Examples of the substituent that the phenylene group and 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 represents a nitrogen atom that forms a ring structure with Q ³ and Sp ^3. Show. Sp ³ and Sp ⁴ are each 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. When two or more —CH ₂ — are —O—, —S—, —NH—, —N (CH ₃ ) —, —C (═O) —, —OC (═O) —, or —C (═O ) Represents a linking group selected from the group consisting of groups substituted with O-.
Q ³ and Q ⁴ are each independently a hydrogen atom, a cycloalkyl group, or a cycloalkyl group in which one or more —CH ₂ — is —O—, —S—, —NH—, —N (CH ₃ )-, -C (= O)-, -OC (= O)-, or a group substituted with -C (= O) O-, or a group represented by formula (Q-1) to formula (Q-5) Any polymerizable group selected from the group consisting of:

In the cycloalkyl group, one or more of —CH ₂ — 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 pyrazolidinyl group, a piperidyl group, a piperazinyl group, and a morpholinyl group. . Of these, a tetrahydrofuranyl group is preferable, and a 2-tetrahydrofuranyl group is more preferable.

In the formula (I), L represents a single bond, —CH ₂ O—, —OCH ₂ —, — (CH ₂ ) ₂ OC (═O) —, —C (═O) O (CH ₂ ) _2. -, -C (= O) O-, -OC (= O)-, -OC (= O) O-, -CH = CH-C (= O) O-, and -OC (= O)- A linking group selected from the group consisting of CH = CH- is shown. L is preferably —C (═O) O— or —OC (═O) —. The m Ls may be the same as or different from each other.

Sp ¹ and Sp ² are each 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. Two or more —CH ₂ — is —O—, —S—, —NH—, —N (CH ₃ ) —, —C (═O) —, —OC (═O) —, or —C (= O) A linking group selected from the group consisting of groups substituted with O-. Sp ¹ and Sp ² are each independently 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. Selected from the group consisting of 1 to 10 linear alkylene groups, —OC (═O) —, —C (═O) O—, —O—, and linear alkylene groups having 1 to 10 carbon atoms. The linking group is preferably a combination of 1 or 2 groups, more preferably a straight-chain 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, ^one of Q ¹ and Q ² represents 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, a compound represented by the formula (I) in JP2013-112231A, a compound represented by the formula (I) in JP2010-70543A, a formula of JP2008-291218A A compound represented by formula (I), a compound represented by formula (I) of Japanese Patent No. 4725516, a compound represented by general formula (II) of JP2013-087109A, JP2007-176927A A compound represented by formula (1-1) of JP2009-28685A, a compound represented by general formula (I) of WO2014 / 10325, JP2016-81035A, And the compounds represented by the formula (1) of JP-A No. 2006-139, and the compounds represented by formula (2-1) and formula (2-2) of JP-A No. 2006-121339, etc. It is below.

Liquid crystal compound represented by 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 represents a single bond, —C (═O) O—, or —O (C═O) —,
L ¹² represents —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 each independently a single bond, —O—, —NH—, —N (CH ₃ ) —, —S—, —C (═O) O—, —OC (═O) —, -OC (= O) O-, ^{or, -C (= O) NR 12} - indicates,
R ¹² represents 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 To 12 linear or branched alkylene groups, any one or more of —CH ₂ — is replaced with —O—, —S—, —NH—, —N (Q ¹¹ ) —, or —C (═O )-Represents a linking group obtained by substitution,
Q ¹¹ represents a hydrogen atom, a cycloalkyl group, or a cycloalkyl group in which one or more —CH ₂ — is —O—, —S—, —NH—, —N (CH ₃ ) —, —C (= O)-, -OC (= O)-, or a group substituted with -C (= O) O-, or a group consisting of groups represented by formula (Q-1) to formula (Q-5) A polymerizable group selected from
Q ¹² represents a hydrogen atom or a polymerizable group selected from the group consisting of groups represented by formula (Q-1) to formula (Q-5);
l ¹¹ represents an integer of 0 to 2,
m ¹¹ represents an integer of 1 or 2,
n ¹¹ represents an integer of 1 to 3,
The plurality of R ¹¹ , the plurality of L ¹¹ , the plurality of L ¹² , the plurality of l ¹¹ , the plurality of Z ¹¹ , the plurality of Sp ¹¹ , and the plurality of Q ¹¹ may be the same as or different from each other.
In the liquid crystal compound represented by the formula (I-11), as R ¹¹ , Q ¹² is selected from the group consisting of groups represented by the formula (Q-1) to the formula (Q-5). It contains at least one group —Z ¹² —Sp ¹² —Q ¹² .
In the liquid crystal compound represented by the formula (I-11), Z ¹¹ is —C (═O) O— or —C (═O) NR ¹² —, and Q ¹¹ is a compound represented by the formula (Q-1) to preferably a -Z ¹¹ -Sp ¹¹ -Q ¹¹ is a polymerizable group selected from the group consisting of groups represented by the formula (Q-5). In the liquid crystal compound represented by the formula (I-11), as R ¹¹ , Z ¹² is —C (═O) O— or —C (═O) NR ¹² —, and Q ¹² is the formula (Q -1) to formula (Q-5) preferably a -Z ¹² -Sp ¹² -Q ¹² is a polymerizable group selected from the group consisting of groups represented by.

Any 1,4-cyclohexylene group contained in the liquid crystal compound represented by the formula (I-11) is a trans-1,4-cyclohexylene group.
As a preferable embodiment of the liquid crystal compound represented by Formula (I-11), L ¹¹ is a single bond, l ¹¹ is 1 (dicyclohexyl group), and Q ¹¹ is Formula (Q-1) to Formula (Q-5). And a compound that is a polymerizable group selected from the group consisting of groups represented by:
As another preferable embodiment of the liquid crystal compound represented by the formula (I-11), m ¹¹ is 2, l ¹¹ is 0, and two R ¹¹ are both —Z ¹² —Sp ¹² —Q ¹² . , Q ¹² is a polymerizable group selected from the group consisting of groups represented by formula (Q-1) to formula (Q-5).

Liquid crystal compound represented by 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 independently 1 to 4 substituents 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 represents 2, n21 represents 0,
when m21 represents 2, two Z ²¹ may be the same or different;
At least one of Z ²¹ and Z ²² is an optionally substituted phenylene group,
L ²¹ , L ²² , L ²³ and L ²⁴ are each independently 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 — A linking group selected from the group consisting of OC (= O) -CH = CH-;
X ²¹ represents —O—, —S—, or —N (Sp ²⁵ —Q ²⁵ ) —, or represents a nitrogen atom that forms a ring structure with Q ²³ and Sp ²³ ,
r ²¹ represents an integer of 1 to 4,
Sp ²¹ , Sp ²² , Sp ²³ , and Sp ²⁵ are each independently 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. In the group, one or more —CH ₂ — is —O—, —S—, —NH—, —N (CH ₃ ) —, —C (═O) —, —OC (═O) —, Or a linking group selected from the group consisting of groups substituted with -C (= O) O-,
Q ²¹ and Q ²² each independently represent any polymerizable group selected from the group consisting of groups represented by formula (Q-1) to formula (Q-5);
Q ²³ represents a hydrogen atom, a cycloalkyl group, or a cycloalkyl group, wherein one or more of —CH ₂ — is —O—, —S—, —NH—, —N (CH ₃ ) —, —C (= O)-, -OC (= O)-, or a group substituted with -C (= O) O-, selected from the group consisting of groups represented by formula (Q-1) to formula (Q-5) Any single polymerizable group, or a single bond in the case where X ²¹ is a nitrogen atom that forms a ring structure with Q ²³ and Sp ²³ ,
Q ²⁵ is a hydrogen atom, a cycloalkyl group, or a cycloalkyl group, wherein one or more of —CH ₂ — is —O—, —S—, —NH—, —N (CH ₃ ) —, —C ( = O)-, -OC (= O)-, or a group substituted with -C (= O) O-, or a group represented by formula (Q-1) to formula (Q-5). When any one of the polymerizable groups selected from the group is selected and Sp ²⁵ is a single bond, Q ²⁵ is not a hydrogen atom.

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 Z ²¹ is a trans-1,4-cyclohexylene group which may have a substituent from the Q ²¹ side, an arylene group which may have a substituent, 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 preferred.

A liquid crystal compound represented by formula (I-31);

In the formula, R ³¹ and R ³² are each independently a group selected from the group consisting of an alkyl group, an alkoxy group, and —C (═O) —X ³¹ —Sp ³³ —Q ³³ ;
n31 and n32 each independently represents an integer of 0 to 4,
X ³¹ represents a single bond, —O—, —S—, or —N (Sp ³⁴ —Q ³⁴ ) —, or represents a nitrogen atom that forms a ring structure with Q ³³ and Sp ³³ ,
Z ³¹ represents a phenylene group which may have a substituent,
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 independently an alkyl group, an alkoxy group, and 1 to 4 substituents selected from the group consisting of —C (═O) —X ³¹ —Sp ³³ —Q ³³ ,
m31 represents an integer of 1 or 2, m32 represents an integer of 0 to 2,
when m31 and m32 are 2, two Z ³¹ and Z ³² may be the same or different;
L ³¹ and L ³² are each independently 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)- Represents a linking group selected from the group consisting of CH = CH-;
Sp ³¹ , Sp ³² , Sp ³³ and Sp ³⁴ are each independently 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. In which one or more —CH ₂ — is —O—, —S—, —NH—, —N (CH ₃ ) —, —C (═O) —, —OC (═O) —, or 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 groups represented by formula (Q-1) to formula (Q-5);
Q ³³ and Q ³⁴ are each independently a hydrogen atom, a cycloalkyl group, or a cycloalkyl group in which one or more —CH ₂ — is —O—, —S—, —NH—, —N (CH ₃ )-, -C (= O)-, -OC (= O)-, or a group substituted with -C (= O) O-, or in formula (Q-1) to formula (Q-5) in the case represented indicates one polymerizable group selected from the group consisting of group, Q ³³ is forming a ring structure with X ³¹ and Sp ^33, may be a single bond, is Sp ³⁴ When it is 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), the black circles indicate the position of bonding 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).

In the formula, R ¹ and R ² are each independently selected from the group consisting of a hydrogen atom, an alkyl group, an alkoxy group, and a group represented by —C (═O) —X ³ —Sp ³ —Q ^3. It is a group. Here, X ³ represents a single bond, —O—, —S—, or —N (Sp ⁴ -Q ⁴ ) —, or represents a nitrogen atom that forms a ring structure with Q ³ and Sp ^3. Show. X ³ is preferably a single bond or —O—. R ¹ and R ² are preferably —C (═O) —X ³ —Sp ³ —Q ³ . R ¹ and R ² are preferably 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 each 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. The above —CH ₂ — is —O—, —S—, —NH—, —N (CH ₃ ) —, —C (═O) —, —OC (═O) —, or —C (═O). A linking group selected from the group consisting of groups substituted with O- is shown. Sp ³ and Sp ⁴ are each independently preferably a linear or branched alkylene group having 1 to 10 carbon atoms, more preferably a linear alkylene group having 1 to 5 carbon atoms, and a straight chain having 1 to 3 carbon atoms. Even more preferred are chain alkylene groups.
Q ³ and Q ⁴ are each independently a hydrogen atom, a cycloalkyl group, or a cycloalkyl group in which one or more —CH ₂ — is —O—, —S—, —NH—, —N (CH ₃ )-, -C (= O)-, -OC (= O)-or -C (= O) O-, or a group represented by formula (Q-1) to formula (Q-5) Any polymerizable group selected from the group consisting of:

  It is also preferable that the compound represented by the formula (I) has a structure represented by the following formula (II-2), for example.

In the formula, A ¹ and A ² each independently represent a phenylene group which may have a substituent or a trans-1,4-cyclohexylene group which may have a substituent. Each independently is an alkyl group, an alkoxy group, and 1 to 4 substituents selected from the group consisting of —C (═O) —X ³ —Sp ³ —Q ³ ;
L ¹ , L ² and L ³ are 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)- Represents a linking group selected from the group consisting of CH = CH-;
n1 and n2 each independently represent an integer of 0 to 9, and n1 + n2 is 9 or less.
^{Q 1, Q 2, Sp 1} , and the definition of Sp ² are the same as those defined for each group in the above formula (I). The definitions of X ³ , Sp ³ , Q ³ , R ¹ , and R ² are the same as 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. Are exemplified.

Two or more liquid crystal compounds may be used 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 is a liquid crystal compound represented by the formula (I) together with the liquid crystal compound satisfying 0.4 ≦ mc ≦ 0.8, 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. 2016/047648. Are exemplified.

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

Formula (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 be;
Z ¹ represents —C (═O) —, —O—C (═O) — or a single bond;
Z ² represents —C (═O) — or —C (═O) —CH═CH—;
R ¹ represents a hydrogen atom or a methyl group;
R ² represents a hydrogen atom, a halogen atom, a linear alkyl group having 1 to 4 carbon atoms, a methoxy group, an ethoxy group, an optionally substituted phenyl group, a vinyl group, a formyl group, a nitro group, or a cyano group. , 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 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 each independently an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an alkoxycarbonyl group having 2 to 5 carbon atoms, or 2 to 4 carbon atoms. An acyl group, a halogen atom or a hydrogen atom, 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 type (IV-2)
In formula (IV-2), P represents an acryl 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 not adjacent to each other CH ₂ may be substituted with —O—, —S—, —OC (═O) —, —C (═O) O— or —OCOO—. ).

The compound represented by the formula (IV) is preferably a compound represented by the following formula (V).
Formula (V)

In the formula (V), n1 represents an integer of 3 to 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 type (IV-3)
In formula (IV-3), P represents an acryl group or a methacryl 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 substituted with-.

N1 represents an integer of 3 to 6, and is preferably 3 or 4.
Z ¹² represents —C (═O) — or —C (═O) —CH═CH—, and preferably represents —C (═O) —.
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). And more preferably 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). More preferably, it represents 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 (IV) include compounds described in paragraphs [0020] to [0036] of JP-A-2014-198814.

  As the liquid crystal compound used in the present invention, a compound represented by the following formula (VI) described in JP-A-2014-198814, in particular, a (meth) acrylate represented by the following formula (VI): A liquid crystal compound having no group is also preferably used.

Formula (VI)

In formula (VI), Z ³ represents —C (═O) — or —CH═CH—C (═O) —;
Z ⁴ represents —C (═O) — or —C (═O) —CH═CH—;
R ³ and R ⁴ are each independently a hydrogen atom, a halogen atom, a linear alkyl group having 1 to 4 carbon atoms, a methoxy group, an ethoxy group, an optionally substituted aromatic ring, a cyclohexyl group, 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 an N-alkyloxycarbamoyl group, N- (2-methacryloyloxyethyl) carbamoyloxy group, N- (2-acryloyloxyethyl) carbamoyloxy group, or the following formula (VI-2): Represents the structure
L ⁵ , L ⁶ , L ⁷ and L ⁸ are each independently an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an alkoxycarbonyl group having 2 to 5 carbon atoms, or 2 to 4 carbon atoms. An acyl group, a halogen atom or a hydrogen atom, 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 type (VI-2)
In formula (VI-2), P represents an acryl group, a methacryl group or a hydrogen atom, and Z ⁵ represents —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. 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 substituted with OC (= O) O-.

The compound represented by the above formula (VI) is preferably a compound represented by the following formula (VII).
Formula (VII)

Wherein (VII), Z ¹³ is, -C (= O) - or -C (= O) represents -CH = CH-;
Z ¹⁴ represents —C (═O) — or —CH═CH—C (═O) —;
R ¹³ and R ¹⁴ are each independently 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) represents the structure represented.

Z ¹³ represents —C (═O) — or —C (═O) —CH═CH—, and preferably represents —C (═O) —.
R ¹³ and R ¹⁴ are each independently 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) represents a structure represented by methyl group, ethyl group, propyl group, methoxy group, ethoxy group, phenyl group, acryloylamino group, methacryloylamino group, or a structure represented by the above formula (IV-3) Preferably, it represents 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 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) described in JP-A-2014-198814, particularly, the two compounds represented by the following formula (VIII) ( A polymerizable liquid crystal compound having a (meth) acrylate group is also preferably used.

Formula (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, - Optionally substituted with O-;
Z ⁵ represents —C (═O) —, —OC (═O) — or a single bond;
Z ⁶ represents —C (═O) —, —C (═O) O— or a single bond;
R ⁵ and R ⁶ each independently represents a hydrogen atom or a methyl group;
L ⁹ , L ¹⁰ , L ¹¹ and L ¹² are each independently an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an alkoxycarbonyl group having 2 to 5 carbon atoms, or 2 to 4 carbon atoms. An acyl group, a halogen atom or a hydrogen atom, 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 formula (VIII) is preferably a compound represented by the following formula (IX).
Formula (IX)

In formula (IX), n2 and n3 each independently represent an integer of 3 to 6;
R ¹⁵ and R ¹⁶ each independently represents a hydrogen atom or a methyl group.

In formula (IX), n2 and n3 each independently represent an integer of 3 to 6, and n2 and n3 are preferably 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 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 includes a chiral agent.
The kind of chiral agent is not particularly limited. The chiral agent may be liquid crystalline or non-liquid crystalline. The chiral agent includes various known chiral agents (for example, liquid crystal device handbook, Chapter 3-4, chiral agent for TN (Twisted Nematic), STN (Super Twisted Nematic), 199 pages, Japan Society for the Promotion of Science, 142nd. From the Committee, 1989). Chiral agents generally contain asymmetric carbon atoms. However, an axially asymmetric compound or a planar asymmetric compound that does not contain an asymmetric carbon atom can also be used as a chiral agent. Examples of the axial asymmetric compound or the planar asymmetric compound include binaphthyl, helicene, paracyclophane, and derivatives thereof. The chiral agent may have a polymerizable group.

In the composition, the content of the chiral agent 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 liquid crystallinity. Therefore, as the chiral agent, a compound having a strong twisting power is preferable so that a twisted orientation with a desired helical pitch can be achieved even with a small amount.
Examples of the chiral agent exhibiting such a strong twisting force include, for example, JP 2002-302487, JP 2002-80478, JP 2002-80851, JP 2002-179668, and JP 2002. -179670, JP-A 2002-338575, JP-A 2002-180051, JP-A 62-81354, WO 2002/006195, JP-A 2011-241215, JP-A 2003-287623 JP-A-2002-302487, JP-A-2002-80478, JP-A-2002-80851, and JP-A-2014-034581 and LC-756 manufactured by BASF, etc. Is mentioned.

(Optional ingredients)
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, the composition preferably contains a polymerization initiator.
The polymerization initiator is preferably a photopolymerization initiator capable of initiating a polymerization reaction by ultraviolet irradiation. Examples of the photopolymerization initiator include α-carbonyl compounds (described in US Pat. Nos. 2,367,661 and 2,367,670), acyloin ether (described in US Pat. No. 2,448,828), α-hydrocarbon substituted aromatic acyloin. Compound (described in US Pat. No. 2,722,512), polynuclear quinone compound (described in US Pat. Nos. 3,046,127 and 2,951,758), a combination of triarylimidazole dimer and p-aminophenyl ketone (US Pat. No. 3,549,367) No. specification), acridine and phenazine compounds (JP-A-60-105667, US Pat. No. 4,239,850) and oxadiazole compounds (US Pat. No. 4,212,970).
Although content in particular of the polymerization initiator in a composition is not restrict | limited, 0.1-20 mass% is preferable with respect to liquid crystal compound total mass, and 1-8 mass% is more preferable.

(Alignment control agent (alignment agent))
The composition may contain an alignment control agent. By including an alignment control agent in the composition, it becomes possible to form a stable or rapid cholesteric liquid crystal phase.
Examples of the orientation control agent include fluorine-containing (meth) acrylate polymers, compounds represented by general formulas (X1) to (X3) described in WO2011 / 162291, and paragraphs [0007] of JP2012-211306. ] To [0029], compounds described in paragraphs [0020] to [0031] of JP2013-47204, compounds described in paragraphs [0165] to [0170] of WO2016 / 009648, WO2016 / 092844, paragraphs [0077] to [0081], and general formulas (Cy201) to (Cy211) described in Japanese Patent No. 4592225. You may contain 2 or more types selected from these. These compounds can reduce the tilt angle of the molecules of the liquid crystal compound or substantially horizontally align them at the air interface of the layer. In the present specification, “horizontal alignment” means that the major axis of the liquid crystal molecule is parallel to the film surface, but it is not required to be strictly parallel. An orientation having an inclination angle of less than 20 ° is meant.
An orientation control agent may be used individually by 1 type, and may use 2 or more types together.
The content of the alignment controller 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 more preferably 0.01 to 5% by mass with respect 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 or an organic solvent. Examples of the organic solvent include amides such as N, 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; 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; and the like. These may be used alone or in combination of two or more.

(Other additives)
Composition is one or more kinds of antioxidants, ultraviolet absorbers, sensitizers, stabilizers, plasticizers, chain transfer agents, polymerization inhibitors, antifoaming agents, leveling agents, thickeners. Other additives such as flame retardants, surfactants, dispersants, and colorants such as dyes and pigments may be included.
In addition, the composition which forms the cholesteric liquid crystal layer 14 contains the particles 20 such as the above-mentioned silica sol and nano diamond in addition to these components as described above.

Such a structure 10 of the present invention can be manufactured by forming a cholesteric liquid crystal layer 14 on a substrate 12.
In forming the cholesteric liquid crystal layer 14, first, a composition containing the liquid crystal compound, chiral agent, and particles 20 as described above is prepared, and the prepared composition is applied to the substrate 12.
The application 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.
In addition, you may implement the process which dries the composition apply | coated to the board | substrate 12 after application | coating as needed. By carrying out the drying treatment, the solvent can be removed from the applied composition.

Next, the composition (composition layer (coating film)) applied on the substrate 12 is heated to align the liquid crystal compound in the composition to a cholesteric liquid crystal phase.
The liquid crystal phase transition temperature of the composition is preferably 10 to 250 ° C., more preferably 10 to 150 ° C. from the viewpoint of production suitability.
As preferable heating conditions, the composition is heated at 40 to 100 ° C. (preferably 60 to 100 ° C.) for 0.5 to 5 minutes (preferably 0.5 to 2 minutes).

When the composition is heated to bring the liquid crystal compound into a cholesteric liquid crystal phase, the composition is cooled or heated to form a cholesteric liquid crystal layer 14 so as to improve the helical induction force of the chiral agent contained in the composition. To do. That is, the coating layer is cooled or heated so that the helical induction power (HTP) of the chiral agent contained in the composition constituting the coating layer (composition layer) formed on the substrate 12 is increased. Apply processing.
By subjecting the coating layer to cooling treatment and heat treatment, the helical induction force of the chiral agent is increased and the twist of the liquid crystal compound is increased. As a result, the orientation of the cholesteric liquid crystal phase (inclination of the helical axis) is changed. Thereby, the bright portion 16 and the dark portion 18 parallel to the substrate 12 are changed, and the cholesteric liquid crystal layer 14 having the bright portion 16 and the dark portion 18 having a wave-like structure (uneven structure) as shown in FIG. 1 (FIG. 3) ( Cholesteric liquid crystal phase composition layer) is formed.

When cooling the composition, it is preferable to cool the composition so that the temperature of the composition is lowered by 30 ° C. or more in that the diffuse reflectance of the cholesteric liquid crystal layer 14 is more excellent. Especially, it is preferable to cool a composition so that it may be 40 degreeC or more at the point which the said effect is more excellent, and it is more preferable to cool a composition so that it may fall 50 degreeC or more. Although there is no restriction | limiting in the upper limit of the reduction temperature range of the above-mentioned cooling process, Usually, it is about 70 degreeC.
In other words, the above-described cooling treatment is intended to cool the composition so that it is T-30 ° C. or lower when the temperature of the composition in the state of the cholesteric liquid crystal phase before cooling is T ° C. .
The cooling method is not particularly limited, and examples thereof include a method in which the substrate on which the composition is disposed is left in an atmosphere at a predetermined temperature.

There is no limitation on the cooling rate in the cooling process, but in order to suitably form the corrugated structure of the bright portion 16 and the dark portion 18 of the cholesteric liquid crystal phase, or the unevenness of the surface 24 of the cholesteric liquid crystal layer 14, the cooling rate Is preferably at a certain speed.
Specifically, the maximum cooling rate in the cooling process is preferably 1 ° C. or more per second, more preferably 2 ° C. or more per second, and further preferably 3 ° C. or more per second. The upper limit of the cooling rate is not particularly limited, but is often 10 ° C. or less per second.

When the liquid crystal compound has a polymerizable group, after cooling or heating, the composition on the substrate 12 is cured and the liquid crystal compound is three-dimensionally cross-linked to fix the cholesteric liquid crystal phase. The liquid crystal layer 14 may be formed.
This curing treatment may be performed simultaneously with the cooling treatment or the heat treatment, or may be performed after the cooling treatment or the heat treatment is performed.

The state in which the cholesteric liquid crystal phase is “fixed” is the most typical and preferred mode in which the orientation of the liquid crystal compound in the cholesteric liquid crystal phase is maintained. However, it is not limited to this. Specifically, in a temperature range of usually 0 to 50 ° C. and -30 to 70 ° C. under harsher conditions, the layer has no fluidity, and is in an oriented form by an external field or external force It means a state in which the fixed alignment form can be kept stable without causing a change. In the present invention, as described later, it is preferable to fix the alignment state of the cholesteric liquid crystal phase by a curing reaction that proceeds by ultraviolet irradiation.
In the layer formed by fixing the cholesteric liquid crystal phase, it is sufficient that the optical properties of the cholesteric liquid crystal phase are maintained in the layer, and the composition in the layer no longer needs to exhibit liquid crystallinity. Absent.

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

  In addition, when the structure of the present invention has a plurality of cholesteric liquid crystal layers, similarly, a composition containing a liquid crystal compound, a chiral agent and particles 20 is prepared and formed on the cholesteric liquid crystal layer previously formed. The cholesteric liquid crystal layer may be formed by coating and orienting the liquid crystal compound in the composition to obtain a state of a cholesteric liquid crystal phase, followed by curing as necessary.

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 portions in the cross section have the wavy structure. Become. Therefore, also in the cholesteric liquid crystal layer formed on the cholesteric liquid crystal layer by a coating method, the bright portion 16 and the dark portion 18 in the cross section have a wave-like structure.
Therefore, when a cholesteric liquid crystal layer is further formed on the cholesteric liquid crystal layer, cooling or heating of the composition for improving the HTP to form a wave structure may be performed as necessary.

In the structure 10 shown in FIG. 1, the surface of the substrate 12 is flat, and the bright portion 16 and the dark portion 18 in the cross section are wavy by changing the orientation of the cholesteric liquid crystal phase (inclination of the helical axis) in the cholesteric liquid crystal layer 14. A cholesteric liquid crystal layer 14 having a structure (a layer of a composition in a cholesteric liquid crystal phase state) is formed.
In the structure of the present invention, the cholesteric liquid crystal layer having a wavy structure in the bright and dark portions in the cross section is not limited to this, and various configurations can be used.

As an example, a convex portion 32 such as a transparent hemisphere is formed on the surface of the substrate 12 as in the structure 30 conceptually shown in FIG. 4 and FIG. 5 which is a partially enlarged view of FIG. The structure which formed the cholesteric liquid crystal layer 34 containing the particle | grains formed by fixing a cholesteric liquid crystal phase so that the part 32 may be covered is illustrated. In addition, since FIG. 4 and FIG. 5 show another example of a wave-like structure, the illustration of particles is omitted.
In this structure 30, the orientation of the cholesteric liquid crystal phase is perpendicular to the formation surface in the same manner as in a normal cholesteric liquid crystal layer. Become a structure.

In this structure 30, if the convex portion 32 is formed, for example, by using a liquid composition containing a transparent resin material, dots are formed by an inkjet method or the like, and cured by ultraviolet irradiation or the like as necessary. Good. Or you may use the thing in which convex parts 32, such as a glass blast mat sheet and a micro lens array sheet, are formed as a substrate.
The cholesteric liquid crystal layer 34 is prepared by preparing a liquid crystal composition containing the liquid crystal compound, the chiral agent, and the particles 20 as described above, coating the liquid crystal composition so as to cover the convex portions 32, and applying the liquid crystal compound to the cholesteric liquid crystal phase. After the alignment in the state, the liquid crystal composition may be cured and formed.
As the shape of the convex portion 32, various shapes such as a spherical shape (substantially spherical shape) can be used in addition to the hemispherical shape (substantially hemispherical shape).

Such a structure of the present invention can be used as a projection image display screen 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 display light of a display (see, for example, JP-A-2003-294948).
Further, the structure can be used for various applications such as a polarizing element, a reflection film, an antireflection film, a viewing angle compensation film, a holography, and an alignment film, which are components of the optical element.

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

  By adjusting the central wavelength of selective reflection of each cholesteric liquid crystal layer according to the emission wavelength range of the light source used for projection and the usage mode of the projection image display member, a clear projected image is displayed with high light utilization efficiency. be able to. In particular, by adjusting the central wavelength of selective reflection of the cholesteric liquid crystal layer according to the emission wavelength region of the light source used for projection, a clear color projection image can be displayed with high light utilization efficiency.

  In addition, for example, the projection image display member can be a half mirror that can be used as a combiner of a head-up display by adopting a structure that is transmissive to light in the visible light region. The projected image display half mirror can display the image projected from the projector so that it can be viewed, and when the projected image display half mirror is observed from the same surface side where the image is displayed, the opposite surface is displayed. You can observe information or landscape on the side at the same time.

  Hereinafter, the features of the present invention will be described more specifically with reference to examples and comparative examples. The materials, amounts used, ratios, processing contents, processing procedures, and the like shown in the following examples can be appropriately changed without departing from the gist of the present invention. Accordingly, the scope of the present invention should not be construed as being limited by the specific examples shown below.

[Preparation of Liquid Crystal Composition 1 and Liquid Crystal Composition 2]
Components shown in Table 1 below were mixed to prepare a liquid crystal composition 1 and a liquid crystal composition 2. In addition, all the quantity of each component is a mass part.

Rod-shaped liquid crystal compound 101

Rod-shaped liquid crystal compound 102

Rod-shaped liquid crystal compound 201

Rod-shaped liquid crystal compound 202

Chiral agent A

Orientation control agent (1)
(In the formulas below, “33” and “67” represent the content (mol%) of each repeating unit relative to all repeating units.)

[Examples 1-8 and Comparative Examples 1-2]
(Preparation of liquid crystal coating liquid)
107.6 parts by mass of the prepared liquid crystal composition 1 or liquid crystal composition 2;
285 parts by mass of methyl acetate (manufactured by Wako Pure Chemical Industries, Ltd.)
50 parts by mass of cyclohexanone (manufactured by Wako Pure Chemical Industries, Ltd.), and
A liquid crystal coating solution was prepared by mixing the particles in the amounts shown in Table 2.
The particles are as follows.
Particle 1: Silica sol having an average particle diameter of 15 nm (manufactured by Nissan Chemical Co., AC-2140Z)
Particle 2: Silica sol having an average particle diameter of 50 nm (manufactured by Nissan Chemical Co., AC-4130Z)
Particle 3: Silica sol having an average particle diameter of 100 nm (manufactured by Nissan Chemical Co., AC-5140Z)
Particle 4: Nanodiamond having an average particle diameter of 50 nm (Vision Development Co., Ltd., FND50)
Particle 5: Nanodiamond with an average particle diameter of 200 nm (Vision Development Co., FND200)
Particle 6: Cross-linked polymethyl methacrylate having an average particle size of 4000 nm (SSX-104, manufactured by Sekisui Chemical Co., Ltd.)

(Formation of structure)
As a substrate, a rubbing-treated PET (poly-ethylene terephthalate) film (manufactured by Toyobo Co., Ltd.) was prepared.
The prepared liquid crystal coating solution was applied to the rubbing treated surface of the substrate using a wire bar. The coating layer of the liquid crystal coating solution was dried at room temperature for 50 seconds, and then heated at 95 ° C. for 1 minute to align the liquid crystal compound.
Thereafter, the coating layer was irradiated with ultraviolet rays (UV (Ultra Violet) light) at 30 ° C. using a Fusion D bulb (lamp 90 mW / cm ² ) at an output of 80% for 8 seconds. A cholesteric liquid crystal layer was formed on the substrate to produce a structure. In the above procedure, after aligning the liquid crystal compound at 95 ° C., the liquid crystal composition was cooled to 30 ° C.

A part of the formed cholesteric liquid crystal layer was peeled off, and the film thickness of the cholesteric liquid crystal layer was measured with a shape measuring laser microscope VK-X200 (manufactured by Keyence Corporation) using a 10 × objective lens.
Further, when the cross section of the structure was cut with an ultramicrotome and the cross section was observed with an SEM (SU8030 type SEM manufactured by Hitachi High-Technologies Corporation), each cholesteric liquid crystal layer had a wavy structure in the bright and dark portions. It could be confirmed. Further, this SEM image was analyzed to measure the helical pitch of the cholesteric liquid crystal phase and the period of the wavy structure (period C1).
As a result, the cholesteric liquid crystal layer formed of the liquid crystal coating liquid prepared using the liquid crystal composition 1 had a film thickness of 3.1 μm, a helical pitch of 290 nm, and a period of a wave structure of 2.5 μm. The selective reflection center wavelength of this cholesteric liquid crystal layer is 450 nm.
In addition, the cholesteric liquid crystal layer formed of the liquid crystal coating liquid prepared using the liquid crystal composition 2 had a film thickness of 4.2 μm, a helical pitch of 450 nm, and a wave-like structure period of 3.0 μm. The selective reflection center wavelength of this cholesteric liquid crystal layer is 680 nm.

[Measurement of haze]
The haze was measured about the produced structure. The haze was measured based on JIS K 7136 using SH-7000 manufactured by Nippon Denshoku Industries Co., Ltd.

[Measurement of reflection performance (45 ° reflection amount)]
In the spectrophotometer V-670 (manufactured by JASCO Corporation) equipped with an absolute reflectance measurement system, the prepared structure is set with the cholesteric liquid crystal layer facing the light source, and 45 ° under the condition of 0 ° incidence 45 ° detection. The height of the reflection performance was evaluated.
The reflection performance at 45 ° is a graph in which the horizontal axis represents the wavelength and the vertical axis represents the reflectance, and after removing the reflectance derived from the substrate, the area of the reflection peak corresponding to the selective reflection wavelength of the cholesteric liquid crystal phase is calculated. The size of this area was calculated and evaluated as the amount of reflection at 45 °.

[Evaluation]
From the measurement results of haze and reflection performance,
The ratio of 45 ° reflection amount / haze is 1.7 or more, and the evaluation is such that both low haze and diffusivity are compatible at an extremely high level S,
The ratio of 45 ° reflection amount / haze is 1.4 or more and less than 1.7, and the evaluation is such that both low haze and diffusion are compatible at a high level A,
The ratio of 45 ° reflection amount / haze is 1.2 or more and less than 1.4.
A 45 ° reflection amount / haze ratio of less than 1.2 was evaluated as C.
The results are shown in Table 2 below.

As shown in Table 2, the structure of the present invention, in which the cholesteric liquid crystal layer has a wave-like structure and contains particles having a particle size smaller than the helical pitch, has both low haze and diffuse reflectivity. It has been obtained. In particular, the ratio between the average particle diameter of the particles and the helical pitch of the cholesteric liquid crystal phase (particle diameter / pitch), and the ratio between the average particle diameter of the particles and the period of the wavy structure (particle diameter / period) are within a preferable range. In Examples 1, 6 and 7, the low haze and diffuse reflection properties are obtained at a high level.
In contrast, Comparative Example 1 in which the average particle diameter of the particles is 4000 nm and exceeds the helical pitch (290 nm) has good diffuse reflectivity but very high haze. Moreover, although the comparative example 2 which does not contain particle | grains has a favorable haze, its diffuse reflectance is low.
From the above results, the effects of the present invention are clear.

  It can be suitably used as a projection image display screen, a half mirror, and the like.

DESCRIPTION OF SYMBOLS 10, 30 Structure 12 Substrate 14, 34 Cholesteric liquid crystal layer 16 Bright part 18 Dark part 20 Particles 24 Surface 32 Convex part 50a, 50b Cholesteric liquid crystal layer C1 Wave-like structure period C2 Uneven period h Uneven height

Claims (6)

A structure having a cholesteric liquid crystal layer formed by fixing a cholesteric liquid crystal phase,
The cholesteric liquid crystal layer includes particles having a particle size smaller than the helical pitch of the cholesteric liquid crystal phase, and a bright portion and a dark portion derived from the cholesteric liquid crystal phase are wavy in a cross section in the thickness direction. A structure   The structure according to claim 1, wherein the cholesteric liquid crystal layer is a three-dimensionally crosslinked polymer material.   The structure according to claim 1 or 2, wherein a content of the particles in the cholesteric liquid crystal layer is 0.01 to 2% by mass.   The structure according to any one of claims 1 to 3, wherein a helical pitch of the cholesteric liquid crystal phase is 220 to 2000 nm.   The ratio between the average particle diameter of the particles and the helical pitch of the cholesteric liquid crystal phase is 0.8 or less as a ratio of average particle diameter / spiral pitch, according to any one of claims 1 to 4. Structure.   The ratio of the average particle diameter of the particles to the period of the waves formed by the bright and dark parts derived from the cholesteric liquid crystal phase in the cholesteric liquid crystal layer is 0.2 or less in terms of the ratio of the average particle diameter / wave period. The structure according to any one of claims 1 to 5.