US-12624292-B2 - Cholesteric liquid crystal film and manufacturing method thereof

US12624292B2US 12624292 B2US12624292 B2US 12624292B2US-12624292-B2

Abstract

Provided are a cholesteric liquid crystal film including a cholesteric liquid crystal, in which, in a cross section in a thickness direction observed with a microscope, the cholesteric liquid crystal film has a stripe pattern in which dark portions and bright portions are alternately arranged, and has a folded structure due to the dark portions at a surface layer portion of one main surface of a pair of main surfaces; and a manufacturing method thereof.

Inventors

Takahiro Hayashi
Satoshi KUNIYASU
Mitsuyoshi Ichihashi

Assignees

FUJIFILM CORPORATION

Dates

Publication Date: 20260512
Application Date: 20220727
Priority Date: 20200131

Claims (6)

1 . A cholesteric liquid crystal film comprising: a cholesteric liquid crystal, wherein, in a cross section in a thickness direction observed with a microscope, the cholesteric liquid crystal film has a stripe pattern in which dark portions and bright portions are alternately arranged, and has a folded structure formed by the dark portions at a surface layer portion of one main surface of a pair of main surfaces which corresponds to a front surface and a back surface of the cholesteric liquid crystal film, and wherein the folded structure formed by the dark portions includes a structure in which two dark portions adjacent to each other are bonded to each other to look like a U shape.
2 . The cholesteric liquid crystal film according to claim 1 , wherein, in the cross section, the dark portions in the stripe pattern is inclined with respect to the main surface.
3 . The cholesteric liquid crystal film according to claim 2 , wherein an inclined angle of the dark portions in the stripe pattern with respect to the main surface is 20° to 90° .
4 . The cholesteric liquid crystal film according to claim 1 , wherein the folded structure due to the dark portions exists in a region from the one main surface to 1/3 of a film thickness.
5 . The cholesteric liquid crystal film according to claim 1 , wherein, in the surface layer portion of the one main surface, the folded structure due to the dark portions exists at 2 to 10 places in 20 dark portions adjacent to each other.
6 . The cholesteric liquid crystal film according to claim 1 , wherein, in a surface layer portion of the other main surface of the pair of main surfaces, the folded structure due to the dark portions does not exist in 20 dark portions adjacent to each other, or exists in less than 2 places in 20 dark portions adjacent to each other.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation application of International Application No. PCT/JP2020/047688, filed Dec. 21, 2020, the disclosure of which is incorporated herein by reference in its entirety. Further, this application claims priority from Japanese Patent Application No. 2020-015748, filed Jan. 31, 2020, the disclosure of which is incorporated herein by reference in its entirety. BACKGROUND OF THE INVENTION 1. Field of the Invention The present disclosure relates to a cholesteric liquid crystal film and a manufacturing method thereof. 2. Description of the Related Art By microscopic observation, it is known that a cholesteric liquid crystal film has a stripe pattern consisting of dark portions and bright portions. For example, FIG. 6 of WO2018/043678A shows an image of a cross section of the cholesteric liquid crystal film by SEM, and the stripe pattern consisting of the dark portions and the bright portions is confirmed. For example, FIG. 5 of JP2005-37735A shows an image of a cross-sectional structure captured by a transmission electron microscope of a cholesteric liquid crystal polarization selective reflective layer, and the stripe pattern consisting of the dark portions and the bright portions is confirmed. SUMMARY OF THE INVENTION The stripe pattern consisting of the dark portions and the bright portions in the cholesteric liquid crystal film indicates an arrangement state of a cholesteric liquid crystal. In a case where an alignment state of the cholesteric liquid crystal differs between a front surface side and a back surface side even though the cholesteric liquid crystal film is a single layer, it is expected that an application of the cholesteric liquid crystal film will be widened. Therefore, the present disclosure has been made in view of the above-described circumstances. An object of an embodiment of the present disclosure is to provide a cholesteric liquid crystal film in which an alignment state of a cholesteric liquid crystal differs between a front surface side and a back surface side and a manufacturing method thereof. The specific methods for achieving the objects include the following aspects. <1>A cholesteric liquid crystal film comprising: a cholesteric liquid crystal, in which, in a cross section in a thickness direction observed with a microscope, the cholesteric liquid crystal film has a stripe pattern in which dark portions and bright portions are alternately arranged, and has a folded structure due to the dark portions at a surface layer portion of one main surface of a pair of main surfaces. <2> The cholesteric liquid crystal film according to <1>, in which, in the cross section, the dark portions in the stripe pattern is inclined with respect to the main surface. <3> The cholesteric liquid crystal film according to <2>, in which an inclined angle of the dark portions in the stripe pattern with respect to the main surface is 20° to 90°. <4> The cholesteric liquid crystal film according to any one of <1> to <3>, in which the folded structure due to the dark portions exists in a region from the one main surface to ⅓ of a film thickness. <5> The cholesteric liquid crystal film according to any one of <1> to <4>, in which, in the surface layer portion of the one main surface, the folded structure due to the dark portions exists at 2 to 10 places in 20 dark portions adjacent to each other. <6> The cholesteric liquid crystal film according to any one of <1> to <5>, in which, in a surface layer portion of the other main surface of the pair of main surfaces, the folded structure due to the dark portions does not exist in 20 dark portions adjacent to each other, or exists in less than 2 places in 20 dark portions adjacent to each other. <7>A manufacturing method of a cholesteric liquid crystal film, comprising: a first step of applying a coating liquid including a solvent, a liquid crystal compound, and a chiral agent onto a substrate to form a coating film; and a second step of applying a shearing force to a surface of the formed coating film with a blade, in which a shear rate in the second step is 1000 seconds−1 or more. According to the embodiment of the present disclosure, a cholesteric liquid crystal film in which an alignment state of a cholesteric liquid crystal differs between a front surface side and a back surface side and a manufacturing method thereof are provided. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an example of a microscopic observation image of a cross section of a cholesteric liquid crystal film according to an embodiment of the present disclosure in a thickness direction. FIG. 2 is a schematic diagram showing an example of a molecular arrangement of a rod-like liquid crystal compound in the cross section of the cholesteric liquid crystal film. FIG. 3 is a schematic diagram showing an example of a manufacturing method of the cholesteric liquid crystal film according to the embodiment of the present disclosure. FIG. 4