Liquid crystal film-forming composition, liquid crystal film, sensor, and optical element

Abstract

To provide a liquid crystal film-forming composition suitable for forming a liquid crystal film that has improved degradation resistance as compared to conventional dry films, and has great wavelength shift (color tone change) when strain and the like occur due to external force.SOLUTION: A liquid crystal film-forming composition contains hydroxy alkyl cellulose with some of hydroxy groups substituted with groups having unsaturated double bonds, and liquid containing water.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to a liquid crystal film-forming composition, a liquid crystal film, a sensor, and an optical element. [Background technology]

[0002] Liquid crystal materials are used as display materials for liquid crystal displays and the like, and are also being applied to photonic devices by taking advantage of their optical properties. For example, cellulose derivatives are known as liquid crystal materials.

[0003] Cellulose derivatives exhibit Bragg reflection due to the cholesteric liquid crystal phase when the side chains in their structures are appropriately modified. One example of a cellulose derivative with liquid crystallinity is hydroxypropyl cellulose, in which the hydrogen atoms of the hydroxyl groups are substituted with substituents containing carbamate groups (urethane bonds).

[0004] Also proposed is a lyotropic liquid crystal material that contains a specific cellulose derivative and a monomer that has a group with an unsaturated double bond in its molecule, and that exhibits rubber elasticity and reflection characteristics (reflected color) in the visible wavelength range at room temperature (see, for example, Patent Document 1). In this lyotropic liquid crystal material, a side chain containing an unsaturated double bond derived from the specific cellulose derivative reacts with an unsaturated double bond contained in a polymerizable monomer to form a crosslinked structure, and the resulting liquid crystal film exhibits rubber elasticity, and an external force (for example, mechanical pressure) causes a wavelength shift in Bragg reflection, i.e., a change in hue. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2019 / 151360 Summary of the Invention [Problem to be solved by the invention]

[0006] Conventional liquid crystal materials are limited to being used as liquid crystal elastic films (dry films) with low solvent content because the hydroxyl groups of cellulose derivatives are replaced with acyl groups or the like to form cross-linked structures. In addition, the liquid crystal elastic film exhibits rubber elasticity, and the side chains of the cellulose derivative are esterified with fatty acids to induce a liquid crystal phase. Eliminating the deterioration of reflection characteristics caused by hydrolysis of the ester moiety is expected to contribute to expanding applications.

[0007] The present disclosure has been made in light of the above. The problem that one embodiment of the present invention aims to solve is to provide a composition for forming a liquid crystal film that is more resistant to deterioration than conventional dry films and is suitable for forming a liquid crystal film that exhibits a large wavelength shift (color change) when, for example, strain occurs due to an external force. The problem that another embodiment of the present invention aims to solve is to provide a liquid crystal film, as well as a sensor and an optical element, that has superior resistance to deterioration compared to conventional dry films and that exhibits a large wavelength shift (color change) when strain is caused by an external force, for example. [Means for solving the problem]

[0008] Specific means for solving the problems include the following aspects. <1> The composition for forming a liquid crystal film contains a hydroxyalkyl cellulose in which some of the hydroxyl groups have been substituted with groups having an unsaturated double bond, and a liquid containing water. <2> The concentration of the hydroxyalkyl cellulose is 60% by mass or more based on the total mass of the liquid crystal film forming composition. <1> 1. The composition for forming a liquid crystal film according to claim 1. <3> The liquid further contains a polar solvent other than water. <1> or the above <2> 1. The composition for forming a liquid crystal film according to claim 1. <4> The polar solvent contains glycerin. <3> 1. The composition for forming a liquid crystal film according to claim 1. <5> The liquid has a glycerin content of 5% by mass to 45% by mass relative to the total content of water and glycerin. <4> 1. The composition for forming a liquid crystal film according to claim 1. <6> The hydroxyalkyl cellulose has a degree of substitution of hydroxyl groups calculated by the following formula 1 of 0.01 to 0.4: <1> ~The above <5> The liquid crystal film-forming composition according to any one of the above items. Degree of substitution of hydroxyl group = total number of groups with unsaturated double bonds present per monomer unit / 3 ...Formula 1 <7> The hydroxyalkyl cellulose has a structural unit represented by the following general formula (1A), and has a degree of substitution of hydroxyl groups calculated by the following formula (2) of 0.01 to 0.4: <1> ~The above <6> The liquid crystal film-forming composition according to any one of the above items. Degree of substitution of hydroxyl groups = R 11 , R 12 and R 13 Total number of groups with unsaturated double bonds in / 3 ...Formula 2

[0009] [ka]

[0010] In formula (1A), X 11 , X 12 and X 13 are each independently a single bond, an alkylene group, -(R 14 -O) h - or -C(=O)-R 15 - represents R 11 , R 12 and R 13 each independently represents a hydrogen atom, a group having an unsaturated double bond (hereinafter also referred to as a "crosslinkable group"), or a hydrophobic group, and R 14 and R 15 each independently represents an alkylene group, h represents an integer of 1 or more and 10 or less, and n11 represents an integer of 2 or more and 800 or less. <8> The hydroxyalkyl cellulose is hydroxypropyl cellulose. <1> ~The above <7> The liquid crystal film-forming composition according to any one of the above items.

[0011] <9> The above-mentioned group having an unsaturated double bond is a group derived from at least one compound selected from the group consisting of acryloyl halide, 2-acryloyloxyethyl isocyanate, 2-methacryloyloxyethyl isocyanate, 1,1-(bisacryloyloxymethyl)ethyl isocyanate, and acrylic anhydride. <7> or the above <8> 1. The composition for forming a liquid crystal film according to claim 1. <10> The above-mentioned group having an unsaturated double bond is a group derived from 2-acryloyloxyethyl isocyanate. <7> ~The above <9> The liquid crystal film-forming composition according to any one of the above items. <11> The above-mentioned method for forming a lyotropic liquid crystal film <1> ~The above <10> The liquid crystal film-forming composition according to any one of the above items. <12> The aforementioned <1> ~The above <11> The liquid crystal film is a crosslinked product of the liquid crystal film-forming composition according to any one of the above. <13> The aforementioned <12> 2. A sensor comprising the liquid crystal film described in . <14> The aforementioned <13> An optical element including the sensor described in . [Effects of the Invention]

[0012] According to one embodiment of the present invention, a composition for forming a liquid crystal film is provided that is superior in resistance to deterioration compared to conventional dry films and is suitable for forming a liquid crystal film that exhibits a large wavelength shift (color change) when, for example, strain occurs due to an external force. According to another embodiment of the present invention, a liquid crystal film, a sensor, and an optical element are provided which have superior resistance to deterioration compared to conventional dry films and which exhibit a large wavelength shift (color change) when subjected to, for example, distortion caused by an external force. [Brief explanation of the drawings]

[0013] [Figure 1] 1 shows transmission spectra of the liquid crystal film in a liquid crystal cell before and after UV light irradiation, where the solid line indicates the transmittance before UV light irradiation and the dashed line indicates the transmittance after UV light irradiation. [Figure 2] 10 is a transmission spectrum showing the transmittance during the compression process of a liquid crystal film using HPC-AcC before and after drying and hardening. [Figure 3] 10 is a transmission spectrum showing the transmittance during the compression process of a liquid crystal film using HPC-AcE before and after drying and hardening. [Figure 4] 10 shows transmission spectra showing the transmittance during the compression process of a liquid crystal film using HPC-bAcC before and after drying and hardening. [Figure 5] 10 is a transmission spectrum showing the transmittance during the compression process of a liquid crystal film using HPC-MAcC before and after drying and hardening. [Figure 6] FIG. 10 is a correlation diagram showing the relationship between normalized wavelength and strain in a compression process after drying of a liquid crystal film containing glycerin and water. [Figure 7] SS curves showing the strength of liquid crystal films during the compression-release process using different types of HPC derivatives. (a) and (b) show the strength of the films before drying, and (c) and (d) show the strength of the films after drying. [Figure 8] (a) and (b) are transmission spectra showing the transmittance of a liquid crystal film with AcC = 0.03 before and after UV irradiation, (c) and (d) are transmission spectra showing the transmittance of a liquid crystal film with AcC = 0.15 before and after UV irradiation, and (e) and (f) are transmission spectra showing the transmittance of a liquid crystal film with AcC = 0.31 before and after UV irradiation. Note that the solid line indicates the transmittance before UV irradiation, and the dashed line indicates the transmittance after UV irradiation. [Figure 9] FIG. 10 is a correlation diagram showing the relationship between normalized wavelength and strain during compression process after drying of liquid crystal films using HPC-AcC with different amounts of AcC introduced. [Figure 10] SS curves showing the strength of liquid crystal films with different amounts of AcC introduced during the compression-release process, where (a) and (b) show the strength of the film before drying, and (c) and (d) show the strength of the film after drying. [Figure 11A] The transmittance spectra of the liquid crystal film with different HPC-AcC concentrations before and after UV irradiation are shown in (a) and (b) for the HPC-AcC concentration of 66% by mass. The solid line indicates the transmittance before UV irradiation, and the dashed line indicates the transmittance after UV irradiation. [Figure 11B]The transmittance spectra of the liquid crystal film with different HPC-AcC concentrations before and after UV irradiation are shown in (c) and (d) for the HPC-AcC concentration of 68% by mass. The solid line indicates the transmittance before UV irradiation, and the dashed line indicates the transmittance after UV irradiation. [Figure 11C] The transmittance spectra of the liquid crystal film with different HPC-AcC concentrations before and after UV irradiation are shown in (e) and (f) for the HPC-AcC concentration of 70% by mass. The solid line indicates the transmittance before UV irradiation, and the dashed line indicates the transmittance after UV irradiation. [Figure 12] FIG. 10 is a correlation diagram showing the relationship between normalized wavelength and strain during compression of liquid crystal films with different HPC-AcC concentrations after drying. [Figure 13] SS curves showing the strength of liquid crystal films with different HPC-AcC concentrations during compression-release processes, where (a) shows the strength of the film before drying, and (b) shows the strength of the film after drying. [Figure 14] 1 shows the transmittance spectra of liquid crystal films with different glycerin concentrations before and after UV light irradiation. The solid line shows the transmittance before UV light irradiation, and the dashed line shows the transmittance after UV light irradiation. [Figure 15] FIG. 10 is a correlation diagram showing the relationship between normalized wavelength and strain in a compression process after drying of liquid crystal films containing different concentrations of glycerin. [Figure 16] SS curves showing the strength of liquid crystal films with different glycerin concentrations during compression-release processes. [Figure 17] FIG. 1A is a schematic cross-sectional view of a compression tuning cell used in the examples, and FIG. 1B is a schematic perspective view of FIG. [Figure 18] (a) is a photograph (magnification: 1x) of the reflected image of the principal surface of the fifth elastic membrane. (b) is a photograph (magnification: 1x) of the reflected image of the principal surface of the eighth elastic membrane. [Figure 19](a) shows the measurement results of the reflection spectrum at the center of the main surface of the fifth elastic membrane. (b) shows the measurement results of the reflection spectrum at the center of the main surface of the eighth elastic membrane. (c) shows the measurement results of the reflection spectrum at the edge of the main surface of the fifth elastic membrane. (d) shows the measurement results of the reflection spectrum at the edge of the main surface of the eighth elastic membrane. DETAILED DESCRIPTION OF THE INVENTION

[0014] The liquid crystal film-forming composition, the liquid crystal film, the sensor, and the optical element of the present disclosure will be described in detail below.

[0015] In the present disclosure, the use of "to" indicating a range of values ​​means that the values ​​before and after it are included as the lower limit and upper limit. In the present disclosure, in the numerical ranges described in stages, the upper or lower limit value described in one numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. Furthermore, in the numerical ranges described in the present disclosure, the upper or lower limit value of the numerical range may be replaced with the value shown in the examples.

[0016] In this specification, when referring to the amount of each component in a composition, if there are multiple substances corresponding to each component in the composition, unless otherwise specified, it means the total amount of the multiple components present in the composition.

[0017] The term "solid content" as used herein means components excluding solvents, and liquid components such as low-molecular-weight components other than solvents are also included in the term "solid content" as used herein.

[0018] In addition, in this specification, both or either of acrylic and methacrylic may be expressed as "(meth)acrylic." For example, "(meth)acrylic acid" includes both acrylic acid and methacrylic acid.

[0019] In this specification, the term "process" includes not only an independent process but also a process that cannot be clearly distinguished from other processes, as long as the intended purpose of the process is achieved.

[0020] In the present disclosure, compounds that are not specified as substituted or unsubstituted may have any substituent within the scope that does not impair the effects of the present disclosure.

[0021] In the present disclosure, a combination of preferred aspects is a more preferred aspect.

[0022] <Composition for forming liquid crystal film> The liquid crystal film-forming composition of the present disclosure contains a hydroxyalkyl cellulose in which a part of the hydroxyl groups is substituted with a group having an unsaturated double bond, and a liquid containing water. The liquid crystal film-forming composition of the present disclosure preferably contains a polymerization initiator, and may further contain other components such as additives as necessary.

[0023] Lyotropic liquid crystal materials have been proposed in the past, such as in Patent Document 1, in which the helical structure is stabilized by making the side chains bulky and hydrophobic, and the liquid crystal film exhibits rubber elasticity by forming a crosslinked structure, resulting in a wavelength shift in Bragg reflection when an external force (e.g., mechanical pressure) is applied. However, conventional liquid crystal materials have been used as so-called dry films (dry films) that contain a small amount of solvent because the crosslinked structure is formed by substituting hydroxyl groups of cellulose derivatives with acyl groups or the like. Depending on the intended use, a so-called wet film (wet film) that contains a solvent such as water may be required. On the other hand, conventional liquid crystal materials require the side chains of cellulose derivatives to be esterified with fatty acids in order to induce a liquid crystal phase, and because they have an ester structure, their reflection characteristics can deteriorate over time due to hydrolysis reactions.

[0024] In light of the above, the present disclosure provides a wet liquid crystal film with a stable chemical structure that incorporates liquids, including water, by simply substituting a portion of the hydroxyl groups in the side chains of hydroxyalkyl cellulose (HAC) with groups containing unsaturated double bonds (i.e., intentionally leaving the hydroxyl groups in the side chains intact) and then carbamate-converting a portion of the side chains. This reduces degradation due to the ester structure, resulting in excellent durability. Furthermore, the hydrophobicity and degree of crosslinking of the HAC, as in conventional HAC, are kept low, allowing the HAC to be moderately crosslinked while maintaining water solubility, enabling it to exhibit wavelength shifts (color changes) upon strain when subjected to external force (e.g., compression). Unlike conventional dry films, such as those described in Patent Document 1, the liquid crystal film obtained using the liquid crystal film-forming composition of the present disclosure is a wet lyotropic cholesteric liquid crystal film that incorporates liquids, including water.

[0025] As described later, the hydroxyalkyl cellulose in the present disclosure contains an appropriate amount of unsubstituted hydroxyl groups, and maintains its water solubility in the liquid crystal film-forming composition. Therefore, the liquid crystal film-forming composition of the present disclosure preferably has a form in which the hydroxyalkyl cellulose and the liquid containing water are compatible with each other.

[0026] (hydroxyalkyl cellulose) The liquid crystal film-forming composition of the present disclosure contains at least one kind of hydroxyalkyl cellulose in which some of the hydroxyl groups are substituted with groups having an unsaturated double bond.

[0027] In the hydroxyalkyl cellulose of the present disclosure, some of the hydroxyl groups in the side chains of the structural units are substituted with groups having unsaturated double bonds. In the present disclosure, some of the hydroxyl groups in the side chains of the structural units of the hydroxyalkyl cellulose are carbamate-modified, and the hydroxyl groups in the side chains are intentionally left, resulting in a stable chemical structure. This suppresses deterioration due to hydrolysis caused by the ester structure, resulting in excellent durability.

[0028] Specifically, the hydroxyalkyl cellulose preferably has a degree of hydroxyl group substitution, as determined by the following formula 1, in the range of 0.01 to 0.4. A degree of hydroxyl group substitution of 0.4 or less indicates that the number of carbamate-modified hydroxyl groups in the hydroxyalkyl cellulose is small. Degree of substitution of hydroxyl group = total number of groups with unsaturated double bonds present per monomer unit / 3 ...Formula 1

[0029] The degree of substitution of hydroxyl groups is an index indicating the degree to which some of the hydroxyl groups among the three hydroxyl groups in the structural unit of hydroxyalkyl cellulose have been substituted with groups having unsaturated double bonds, and specifically refers to the average number of hydroxyl groups substituted with groups having unsaturated double bonds (preferably 0.4 or less). The structural unit refers to the monomer unit constituting the polymer (specifically, the structural unit derived from D-glucopyranose (β-glucose)).

[0030] A degree of hydroxyl substitution of 0.01 or more indicates that groups having unsaturated double bonds have been actively introduced. On the other hand, a degree of hydroxyl substitution of 0.4 or less indicates that the cellulose derivative has enough unsaturated double bond groups introduced to exhibit elasticity. In particular, the degree of substitution of hydroxyl groups is preferably in the range of 0.1 to 0.4, more preferably in the range of 0.15 to 0.35, and even more preferably in the range of 0.15 to 0.25.

[0031] Specifically, when the hydroxyalkyl cellulose has a molecular structure represented by the general formula (1A) described later, the degree of substitution of the hydroxyl group is 11 , R 12 , and R 13 is the average number of "groups having an unsaturated double bond" introduced at the positions That is, the hydroxyalkyl cellulose preferably has a structural unit represented by the general formula (1A) and has a degree of substitution of hydroxyl groups calculated by the following formula (2) of 0.01 to 0.4. Degree of substitution of hydroxyl groups = R 11 , R 12 and R13 Total number of groups with unsaturated double bonds in / 3 ...Formula 2

[0032] The hydroxyalkyl cellulose of the present disclosure contains hydroxyl groups in its structural units and is water-soluble. From this viewpoint, the average number of hydroxyl groups per structural unit is preferably 2.4 or more, and more preferably 2.7 or more.

[0033] The hydroxyalkyl cellulose is preferably a cellulose derivative having a molecular structure represented by the following general formula (1A). In the molecular structure represented by general formula (1A), [ ] indicates a structural unit (monomer unit).

[0034] [ka]

[0035] In general formula (1A), X 11 , X 12 and X 13 are each independently a single bond, an alkylene group, -(R 14 -O) h - or -C(=O)-R 15 - represents R 11 , R 12 and R 13 each independently represents a hydrogen atom, a group having an unsaturated double bond (a crosslinkable group), or a hydrophobic group; R 14 and R 15 each independently represents an alkylene group, h represents an integer of 1 or more and 10 or less, and n11 represents an integer of 2 or more and 800 or less.

[0036] In general formula (1A), X 11 , X 12 and X 13The alkylene group represented by the formula (I) is not particularly limited, and examples thereof include linear or branched alkylene groups having 1 to 18 carbon atoms (preferably 1 to 12, more preferably 1 to 4), and cyclic cycloalkylene groups having 3 to 18 carbon atoms (preferably 3 to 12). Examples of linear or branched alkylene groups include methylene, ethylene, n-propylene, isopropylene, n-butylene, isobutylene, sec-butylene, tert-butylene, n-pentylene, and isopentylene. Examples of cyclic alkylene groups include cyclopentylene and cyclohexylene.

[0037] In general formula (1A), X 11 , X 12 and X 13 Represented by -(R 14 -O) h - is an alkyleneoxy group (an alkylene ether group) or a polyalkyleneoxy group (a polyalkylene ether group). -(R 14 -O) h - an alkylene group (-R 14 -) includes the alkylene groups exemplified above (X 11 , X 12 and X 13 The alkylene groups represented by -(R 14 -O) h Examples of - include an ethyleneoxy group, a polyethyleneoxy group, a propyleneoxy group, and a polypropyleneoxy group. In general formula (1A), h is preferably 1 or more and 6 or less, more preferably 1 or more and 4 or less, even more preferably 1 or more and 3 or less, and particularly preferably 1, from the viewpoint of obtaining a liquid crystal film having appropriate elasticity by crosslinking.

[0038] In general formula (1A), X 11 , X 12 and X 13 -C(=O)-R 15 - an alkylene group (-R 15 -) includes the alkylene groups exemplified above (X11 , X 12 and X 13 Examples include alkylene groups similar to those represented by -C(=O)-R 15 Examples of - include -C(=O)-CH2-, -C(=O)-C2H4-, and -C(=O)-C3H6-.

[0039] The alkylene group, -(R 14 -O) h - and -C(=O)-R 15 The - may have a substituent. Examples of the substituent include a linear or branched alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, and a halogen atom. When there are two or more substituents, the respective substituents may be the same or different.

[0040] In addition, in the hydroxyalkyl cellulose of the present disclosure, X 11 , X 12 and X 13 is X 11 , X 12 and X 13 It is preferable that none of X represents a single bond. 11 , X 12 and X 13 It is more preferable that the structure satisfies the following inequality: X represents a group other than a single bond 11 , X 12 and X 13 Number of ≧ 2×n11

[0041] In general formula (1A), R 11 , R 12 and R 13The group having an unsaturated double bond in the formula (1C) is not particularly limited, and examples thereof include a group represented by the general formula (1C) described below, a vinyl group, an allyl group, a vinyloxy group, an isopropenyl group, a 1-propenyl group, a 2-butenyl group, a 3-butenyl group, a 1,3-butadienyl group, a 2-pentenyl group, a geranyl group, an oleyl group, a cycloalkenyl group (e.g., a 2-cyclopenten-1-yl group, a 2-cyclohexen-1-yl group), a vinylbenzyl group, and a cinnamyl group.

[0042] R 11 , R 12 and R 13 Examples of the hydrophobic group in the formula (I) include a linear or branched alkyl group having 1 to 18 carbon atoms, a cycloalkyl group having 3 to 18 carbon atoms, an aryl group having 6 to 18 carbon atoms, an aralkyl group having 7 to 20 carbon atoms, a linear or branched acyl group having 2 to 18 carbon atoms, a linear or branched alkoxy group having 1 to 18 carbon atoms, -COOR 1A A carboxylic acid ester group represented by the formula: or a halogen atom is preferred. 1A Examples of the alkyl group include a linear or branched alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, and an aryl group having 6 to 12 carbon atoms. Among the hydrophobic groups, from the viewpoint of ease of synthesis of the cellulose derivative, an acyl group having 2 to 18 carbon atoms (which may be either linear or branched; the same applies below) is more preferred, an acyl group having 2 to 8 carbon atoms is more preferred, an acyl group having 2 to 4 carbon atoms is even more preferred, and an acyl group having 4 carbon atoms (i.e., a butyryl group) is particularly preferred.

[0043] The linear or branched alkyl group having 1 to 18 carbon atoms may be substituted or unsubstituted. Examples of the unsubstituted linear or branched alkyl group having 1 to 18 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, and a tert-butyl group. Examples of the substituent in the linear or branched alkyl group having 1 to 18 carbon atoms that may be substituted include the same substituents as those exemplified above. The cycloalkyl group having 3 to 18 carbon atoms may be unsubstituted or substituted. Examples of the unsubstituted cycloalkyl group having 3 to 18 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a methylcyclopentyl group, a methylcyclohexyl group, and a methylcycloheptyl group. Examples of the substituent in the optionally substituted cycloalkyl group having 3 to 18 carbon atoms include the same substituents as those exemplified above.

[0044] The aryl group having 6 to 18 carbon atoms may be substituted or unsubstituted. Examples of the unsubstituted aryl group having 6 to 18 carbon atoms include a phenyl group and a naphthyl group. Examples of the substituent in the optionally substituted aryl group having 6 to 18 carbon atoms include the same as the substituents described above. The aralkyl group having 7 to 20 carbon atoms may be unsubstituted or substituted. Examples of the unsubstituted aralkyl group having 7 to 20 carbon atoms include a benzyl group, a phenylethyl group, and a phenylethenyl group. Examples of the substituent in the optionally substituted aralkyl group having 7 to 20 carbon atoms include the same substituents as those exemplified above.

[0045] The linear or branched acyl group having 2 to 18 carbon atoms may be unsubstituted or substituted. Examples of the unsubstituted linear or branched acyl group having 2 to 18 carbon atoms include an acetyl group, a propionyl group, a butyryl group, an isobutyryl group, a hexanoyl group, an octanoyl group, and a benzoyl group. Examples of the substituent in the linear or branched acyl group having 2 to 18 carbon atoms that may be substituted include the same substituents as those exemplified above.

[0046] The linear or branched alkoxy group having 1 to 18 carbon atoms may be substituted or unsubstituted. Examples of the unsubstituted linear or branched alkoxy group having 1 to 18 carbon atoms include a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a hexyloxy group, a phenoxy group, and a benzyloxy group. Examples of the substituent in the linear or branched alkoxy group having 1 to 18 carbon atoms that may be substituted include the same substituents as those exemplified above.

[0047] -COOR 1A The carboxylic acid ester group represented by the formula (I) may be unsubstituted or substituted. Specific examples of the unsubstituted carboxylic acid ester group include linear or branched alkyl ester groups having 2 to 12 carbon atoms (e.g., methyl ester group, ethyl ester group), cycloalkyl ester groups having 4 to 12 carbon atoms (e.g., cyclopropyl ester group, cyclobutyl ester group), and aryl ester groups having 7 to 12 carbon atoms (e.g., phenyl ester group). The above R of the optionally substituted carboxylic acid ester group 1A Examples of the substituent in (a linear or branched alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, or an aryl group having 6 to 12 carbon atoms) include the same substituents as those exemplified above. Examples of the halogen atom include a fluorine atom, a chlorine atom, and a bromine atom.

[0048] In general formula (1A), n11 is 30 or more and 800 or less, preferably 30 or more and 400 or less, and more preferably 30 or more and 300 or less, from the viewpoint of obtaining a liquid crystal film having appropriate elasticity by crosslinking.

[0049] When n11 is 2 or more, the plurality of structural units may be the same or may be 11 , X 12 and X 13 and R 11 , R 12 and R 13 At least one of the above may be different, resulting in structural units that are different from each other.

[0050] In general formula (1A), R 11 , R 12 and R 13 Preferred embodiments of the group having an unsaturated double bond represented by the formula (I) will be described later.

[0051] The molecular structure represented by the general formula (1A) is preferably a molecular structure represented by the following general formula (1A-1).

[0052] [ka]

[0053] In general formula (1A-1), R 1 each independently represents -CH-, -CH-CH-, or -CH-CH(CH)-; R 11 , R 12 and R 13 each independently represents a hydrogen atom, a group having an unsaturated double bond, or a hydrophobic group; m1, t1, and r1 each independently represent an integer of 0 or more and 10 or less; and n13 represents an integer of 2 or more and 800 or less. The three Rs in the formula 1 may all represent the same group, or three R 1 One of the R may be different from the other two. For example, all R 1 may represent -CH2-CH2- or -CH2-CH(CH3)-, or one R 1 represents -CH2-, and the other two R 1 may represent -CH2-CH(CH3)-.

[0054] In general formula (1A-1), R 11 , R 12 and R 13 represents R in the above general formula (1A). 11 , R 12 and R 13 is synonymous with. In general formula (1A-1), m1, t1, and r1 are each independently preferably 0 to 8, more preferably 0 to 5, and even more preferably 0 to 3, from the viewpoint of ease of synthesis of the cellulose derivative.

[0055] In general formula (1A-1), n13 has the same meaning as n11 in general formula (1A) above, and the preferred range is also the same. That is, in general formula (1A-1), n13 is 30 or more and 800 or less, preferably 30 or more and 400 or less, and more preferably 30 or more and 300 or less, from the viewpoint of obtaining a liquid crystal film having appropriate elasticity by crosslinking. When n13 is 2 or more, the multiple structural units may be the same or may have different structures.

[0056] In general formula (1A-1), all R 1 When represents -CH2-CH(CH3)-, the molecular structure is represented by the following general formula (1a).

[0057] [ka]

[0058] In general formula (1a), R 11 , R 12 , R 13 and n13 represents R in general formula (1A-1). 11 , R 12 , R 13 and n13. In addition, m11, t11, and r11 have the same meanings as m1, t1, and r1 in general formula (1A-1).

[0059] In general formula (1A-1), R 1 When represents -CH2-CH2-, the molecular structure is represented by the following general formula (1b).

[0060] [ka]

[0061] In general formula (1b), R 11 , R 12 , R 13 and n13 represents R in general formula (1A-1). 11 , R 12 , R 13 and n13. In addition, m12, t12, and r12 have the same meanings as m1, t1, and r1 in general formula (1A-1).

[0062] -Group having an unsaturated double bond- Next, the group having an unsaturated double bond (crosslinkable group) will be described. In general formula (1A), R 11 , R 12 and R 13 As the group having an unsaturated double bond represented by the formula (1), a group represented by the following general formula (1C) is preferred from the viewpoint of obtaining a liquid crystal film having appropriate elasticity by crosslinking.

[0063] [ka]

[0064] In general formula (1C), R 1C represents a hydrogen atom or a methyl group, and X 18 represents a single bond or a linking group formed by linking one or more groups selected from the group consisting of a linear or branched alkylene group having 1 to 18 carbon atoms, a cycloalkylene group having 3 to 18 carbon atoms, an arylene group having 6 to 18 carbon atoms, -O-, -NH-, -S-, and -C(=O)-, and p1 represents an integer of 1 or 2. 18 The valence of is p1+1. ** represents X in the general formula (1A). 11 , X 12 , or X 13 or X 11 , X 12 , or X 13 When is a single bond, it represents the part that bonds to the oxygen atom at the 2nd, 3rd, or 6th position of the cellulose skeleton. Also, ** represents the part that bonds to the oxygen atom at the 2nd, 3rd, or 6th position of the cellulose skeleton. 16 or X17 or X 16 or X 17 When is a single bond, it represents the part that bonds to the oxygen atom at the 3rd or 6th position of the cellulose skeleton. In general formula (1C), X 18 Examples of the linear or branched alkylene group having 1 to 18 carbon atoms and the cycloalkylene group having 3 to 18 carbon atoms represented by the formula (1A) include X 11 , X 12 and X 13 The alkylene group may be the same as the alkylene group represented by the following formula: In general formula (1C), X 18 The arylene group having 6 to 18 carbon atoms represented by the following formula is not particularly limited, but examples thereof include a phenylene group and a naphthalene group. The alkylene group, linear or branched alkylene group, cycloalkylene group, and arylene group may have a substituent. Examples of the substituent include the same substituents as those exemplified above. In general formula (1C), X 18 The linking group formed by linking one or more selected from the group consisting of -O-, -NH-, -S-, and -C(=O)- is not particularly limited, and examples thereof include -C(=O)-NH-(CH2)2-O-, -C(=O)-NH-(CH2)2-O-(CH2)2-O-, and -C(=O)-NH-C(CH3)-(CH2-O-)2. In general formula (1C), X 18 is preferably a single bond or -C(=O)-NH-(CH2)2-O-. In the group represented by general formula (1C), R 1C is a hydrogen atom or a methyl group, and X 18 A group in which is a single bond and p1 is 1 is a (meth)acryloyl group.

[0065] In the general formula (1C), p1 is preferably 1. Preferred embodiments of the group represented by general formula (1C) include groups represented by formulas (1C-1) to (1C-6) described below. Specific examples of the group represented by general formula (1C) will be described later.

[0066] A preferred embodiment of the cellulose derivative having a molecular structure represented by general formula (1A) is a cellulose derivative having a molecular structure represented by general formula (1a) or a cellulose derivative having a molecular structure represented by general formula (1b). Specifically, in general formula (1a), 11 , R 12 or R 13 ) is an acyl group having 2 to 4 carbon atoms (particularly preferably a butyryl group), and the group (R 11 , R 12 or R 13 ) is a (meth)acryloyl group or -C(=O)-NH-(CH2)2-OC(=O)-CH=CH2, m11, t11 and r11 are each independently an integer of 0 or more and 3 or less, and n13 is 2 or more and 300 or less; 11 , R 12 or R 13 ) is an acyl group having 2 to 4 carbon atoms (particularly preferably a butyryl group), and the group (R 11 , R 12 or R 13 ) is a (meth)acryloyl group or -C(=O)-NH-(CH2)2-OC(=O)-CH=CH2, m12, t12, and r12 are each independently an integer of 0 or more and 3 or less, and n13 is 2 or more and 300 or less.

[0067] Examples of groups represented by general formula (1C) (examples of groups having an unsaturated double bond) are shown below. The groups represented by general formula (1C) are not limited to these. In the following general formulas (1C-1) to (1C-6), ** indicates the bonding position.

[0068] [ka]

[0069] [ka]

[0070] The group represented by general formula (1C-5) is a group represented by general formula (1C) in which X 18 is a trivalent linking group represented by the following general formula (1C-7), and R 1C is a hydrogen atom and p1 is 2. In general formula (1C-7), *** represents the moiety that bonds to the carbon atom that bonds to CO in (COCH=CH2) in general formula (1C-5) above.

[0071] [ka]

[0072] Among the groups represented by the above general formula (1C) (an example of a group having an unsaturated double bond), from the viewpoint of obtaining a liquid crystal film having appropriate elasticity by crosslinking, the groups represented by the general formulae (1C-1), (1C-3), (1C-5) and (1C-6) are preferred, and the groups represented by the general formulae (1C-1) and (1C-3) are more preferred.

[0073] Of the above, the group having an unsaturated double bond is preferably a group derived from at least one compound selected from the group consisting of acryloyl halide (preferably acryloyl chloride), 2-acryloyloxyethyl isocyanate, 2-methacryloyloxyethyl isocyanate, 1,1-(bisacryloyloxymethyl)ethyl isocyanate, and acrylic anhydride, and more preferably a group derived from 2-acryloyloxyethyl isocyanate.

[0074] The hydroxyalkyl cellulose in the present disclosure is preferably hydroxypropyl cellulose.

[0075] (Degree of hydroxyl group substitution) The degree of substitution of hydroxyl groups was determined by nuclear magnetic resonance (1 It is calculated from the integral value of the characteristic proton peaks of each substituent by H-NMR. Specifically, a solution of hydroxyalkyl cellulose dissolved in deuterated chloroform is measured under the following conditions: 1 H-NMR spectrum was measured. 1 Based on the H-NMR spectrum, it is calculated based on the integral values ​​of proton peaks derived from groups with unsaturated double bonds, proton peaks derived from the cellulose skeleton (for example, proton peaks in β-glucose monomer units), and, if the cellulose skeleton is hydroxypropyl cellulose (HPC), proton peaks derived from HPC, proton peaks of methine groups possessed by hydroxypropyl groups in the HPC chain, etc. The average number of hydroxyl groups per structural unit (monomer unit) is calculated by subtracting the degree of substitution of hydroxyl groups calculated by the above method from 3. -Measurement conditions- Device: BRUKER: ULTRASHIELD400PLUS (model number) Frequency: 400MHz

[0076] (Weight average molecular weight) The weight average molecular weight of the hydroxyalkyl cellulose is preferably 20,000 or more and 200,000 or less, more preferably 50,000 or more and 200,000 or less, and even more preferably 100,000 or more and 200,000 or less, from the viewpoint of obtaining a liquid crystal film with appropriate elasticity by crosslinking.

[0077] The weight-average molecular weight is a value calculated (using polystyrene as a standard) by gel permeation chromatography (GPC). Specifically, it is calculated using a molecular weight calibration curve prepared using polystyrene standard samples from the measurement results obtained under the following measurement conditions: -Measurement conditions- Equipment: Tosoh Corporation: HLC-8220GPC (model number) Solvent: Tetrahydrofuran Column: Tosoh Corporation: 0021815 TSKgel SuperMultiporeHZ-N (particle diameter 3 μm, inner diameter 4.6 mm x length 15 cm) Flow rate: 0.15mL / min Sample concentration: 2.0% by mass Injection volume: 10μL Detector: Differential refractive index detector Temperature: 40℃

[0078] Specific examples of the molecular structure represented by general formula (1A) are shown below. The molecular structure represented by general formula (1A) is not limited to these. t1, r1, m1, and n13 in the molecular structure are synonymous with t1, r1, m1, and n13 in general formula (1A-1), which is a preferred embodiment of general formula (1A), and may be appropriately selected within the range of the weight-average molecular weight of the hydroxyalkyl cellulose.

[0079] [ka]

[0080] The concentration of the hydroxyalkyl cellulose is preferably 60% by mass or more relative to the total mass of the liquid crystal film-forming composition, since this increases the wavelength shift (hue change) when an external force is applied. For the same reason, the upper limit of the hydroxyalkyl cellulose concentration is preferably 75% by mass. Among these, the concentration of the hydroxyalkyl cellulose is more preferably 60% to 70% by mass, and even more preferably 65% ​​to 70% by mass.

[0081] (liquid containing water) The composition for forming a liquid crystal film of the present disclosure contains a liquid containing water. When a liquid crystal film is formed, the liquid containing water is contained in the liquid crystal film, so that a wet liquid crystal film is obtained.

[0082] The water-containing liquid may be water alone or a mixture of water and another liquid. From the viewpoint of stabilizing the composition and the liquid crystal film to be produced, the other liquid is preferably a liquid that is compatible with water. "Compatible with water" means that the liquid has a water solubility of 0.1 g or more in 1 g of water at 25°C.

[0083] The other liquid is preferably a polar solvent, and from the viewpoint of enabling the produced film to maintain a wet state even after drying (i.e., after water has evaporated), a nonvolatile solvent having a boiling point of 150° C. or higher is more preferred, and a nonvolatile solvent having a boiling point of 200° C. or higher is even more preferred. Specific examples of the other liquid include alcohols, ethers, and ionic liquids, and more preferably solvents selected from the group consisting of alcohols having a boiling point of 150° C. or higher (even more preferably 200° C. or higher) and ethers having a boiling point of 150° C. or higher (even more preferably 200° C. or higher).

[0084] The alcohol is preferably a dihydric or higher alcohol, and suitable examples thereof include dihydric alcohols (e.g., ethylene glycol (boiling point (bp) 198°C), 1,3-propanediol (bp 215°C), 1,2-butanediol (bp 193°C), 1,2-hexanediol (bp 223°C), etc.) and trihydric alcohols (e.g., glycerin (bp 290°C)), etc.). Of these, glycerin is preferred.

[0085] Examples of the ether include alkyl ethers of ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, and glycerin. Specific examples include alkyl ethers such as ethylene glycol monomethyl ether, ethylene glycol diethyl ether, diethylene glycol monomethyl ether, diethylene glycol diethyl ether, propylene glycol monoethyl ether, and dipropylene glycol dimethyl ether.

[0086] Examples of the ionic liquid include 1-hexyl-3-methylimidazolium bromide, 1-allyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium bromide, and 1-butyl-3-methylimidazolium chloride.

[0087] When other liquids are contained, the ratio of the other liquid in the mixture of the other liquid and water is preferably in the range of more than 0% by mass to 45% by mass or less, more preferably 5% to 45% by mass. When glycerin, for example, is contained as the other liquid, the ratio of the other liquid in the mixture of the other liquid and water is more preferably 20% to 45% by mass, even more preferably 30% to 45% by mass, and particularly preferably 40% to 45% by mass. When the content ratio of the other liquid is within the above range, the wavelength shift (hue change) when an external force is applied becomes large, and the film after drying has flexibility, making it easier for the wavelength shift to occur sharply.

[0088] The content of the water-containing liquid in the liquid crystal film forming composition is preferably in the range of 10% by mass to 60% by mass, more preferably 20% by mass to 50% by mass, based on the total mass of the liquid crystal film forming composition.

[0089] (Polymerization initiator) The liquid crystal film-forming composition of the present disclosure may contain a polymerization initiator. As the polymerization initiator, known polymerization initiators can be used, for example, thermal polymerization initiators and photopolymerization initiators. Among them, photopolymerization initiators are preferred.

[0090] Examples of the photopolymerization initiator include 2-hydroxy-2-methyl-1-phenylpropan-1-one (HMPP), acetophenone, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone (HHEMPP), 2-methyl-4'-(methylthio)-2-morpholinopropiophenone, 2-benzyl-2-(dimethylamino)-4'-morpholinobutyrophenone, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, and bis(2,6-difluoro-3-(1-hydropyrrol-1-yl)phenyl)titanocene.

[0091] The content of the polymerization initiator in the liquid crystal film forming composition is preferably in the range of 0.03 to 0.06% by mass, more preferably 0.03 to 0.05% by mass, based on the total mass of the liquid crystal film forming composition.

[0092] (Other ingredients) The liquid crystal film-forming composition of the present disclosure may contain other components within the range that does not significantly impair the effects of the present disclosure, such as polymerizable monomers, crosslinking agents, flame retardants, compatibilizers, antioxidants, release agents (peeling agents), light-resistant agents, weathering agents, modifiers, antistatic agents, and hydrolysis inhibitors.

[0093] The liquid crystal film-forming composition of the present disclosure is used for forming a liquid crystal film, and is suitable for forming a lyotropic liquid crystal film, and more suitable for forming a lyotropic cholesteric liquid crystal film.

[0094] <Liquid crystal film> The liquid crystal film of the present disclosure is a crosslinked product of the above-described liquid crystal film-forming composition of the present disclosure. The liquid crystal film of the present disclosure is a crosslinked product of the liquid crystal film-forming composition of the present disclosure, and has a three-dimensional structure within the film. The liquid crystal film of the present disclosure is a lyotropic liquid crystal film, and is preferably a lyotropic cholesteric liquid crystal film.

[0095] The liquid crystal film has a three-dimensional crosslinked structure formed by the polymerization reaction of the group having an unsaturated double bond in the structural unit of hydroxyalkyl cellulose. In the present disclosure, the crosslinking reaction proceeds by substituting a group having an unsaturated double bond for a part of the hydroxyl group in the structural unit of hydroxyalkyl cellulose, so that the liquid crystal film maintains flexibility while providing the film with a suitable strength. This allows the liquid crystal film to sensitively and significantly respond to strain caused by external force, resulting in a change in hue. For example, when compressive force is applied to the liquid crystal film, the wavelength of Bragg reflection in the liquid crystal film changes, resulting in a reflected light (hue change) that corresponds to the compressive force.

[0096] The presence of a three-dimensional crosslinked structure can be confirmed by checking whether the liquid crystal film before and after crosslinking dissolves in a solvent (e.g., acetone). The liquid crystal film after crosslinking does not dissolve in the solvent because it has a three-dimensional crosslinked structure. In contrast, the liquid crystal film before crosslinking, which does not have a three-dimensional crosslinked structure, dissolves in the solvent. The formation of a three-dimensional crosslinked structure can be confirmed by checking whether the liquid crystal film dissolves in the solvent.

[0097] -Preparation of liquid crystal film- The liquid crystal film can be produced by a method including a step of applying the liquid crystal film-forming composition of the present disclosure onto a substrate (hereinafter also referred to as a "liquid crystal material application step"), and a step of heat-treating the liquid crystal film-forming composition applied onto the substrate (hereinafter also referred to as a "heat treatment step") or a step of irradiating it with ultraviolet light (hereinafter also referred to as an "ultraviolet light irradiation step").

[0098] (liquid crystal material application process) The liquid crystal material application step is a step of applying a liquid crystal film-forming composition onto a substrate. The substrate is not particularly limited and can be appropriately selected from commonly used substrates depending on the purpose. Examples of the substrate that can be used include glass substrates, plastic substrates (e.g., polyethylene naphthalate (PEN) substrates, polyethylene terephthalate (PET) substrates, polycarbonate (PC) substrates, polyimide (PI) substrates, etc.), metal substrates such as aluminum substrates and stainless steel substrates, and semiconductor substrates such as silicon substrates.

[0099] The thickness and shape of the substrate are not particularly limited, and are preferably selected appropriately depending on the purpose. Examples of methods for applying the liquid crystal material onto the substrate include coating methods such as spin coating, dipping, and spraying; ink jet methods; screen printing; and injection methods such as reduced pressure injection.

[0100] (Heat treatment process) The heat treatment step is a step of subjecting the liquid crystal film forming composition applied onto the substrate to a heat treatment to harden the liquid crystal film forming composition. The heat treatment step cleaves the unsaturated double bonds of the hydroxyalkyl cellulose before crosslinking, causing a polymerization reaction to form a crosslinked structure. In the present disclosure, the liquid crystal film exhibits elasticity while retaining flexibility.

[0101] The heat treatment method is not particularly limited, and may be, for example, a heat treatment method using a known heating device, which is not particularly limited, and examples of the heating device include an oven, an infrared heater, and a hot plate. From the viewpoint of providing appropriate rubber elasticity and fixing the alignment at the wavelength of Bragg reflection, the heat treatment temperature is preferably 25° C. or higher and 130° C. or lower, more preferably 25° C. or higher and 120° C. or lower, and even more preferably 25° C. or higher and 110° C. The heat treatment temperature is controlled so that the liquid crystal material is in the above range.

[0102] (Ultraviolet irradiation process) The ultraviolet ray irradiation step is a step in which the liquid crystal film forming composition applied onto the substrate is irradiated with ultraviolet rays to cure the liquid crystal film forming composition. The ultraviolet irradiation step cleaves the unsaturated double bonds of the hydroxyalkyl cellulose before crosslinking, causing a polymerization reaction to form a crosslinked structure. In the present disclosure, the liquid crystal film exhibits elasticity while retaining flexibility.

[0103] The temperature during irradiation with ultraviolet light (hereinafter referred to as UV irradiation temperature) is preferably 0° C. to 100° C., more preferably 5° C. to 50° C., and even more preferably 10° C. to 40° C. The UV irradiation temperature is controlled so that the liquid crystal material is within the above range.

[0104] The ultraviolet radiation intensity (hereinafter referred to as UV radiation intensity) is 1 mW / cm 2 ~20mW / cm 2 is preferred, and more preferably 5 mW / cm 2 ~20mW / cm 2 and more preferably 10 mW / cm 2 ~20mW / cm 2 is.

[0105] The irradiation time of ultraviolet light (hereinafter referred to as UV irradiation time) is preferably 5 seconds to 40 minutes, and more preferably 5 minutes to 20 minutes.

[0106] In the ultraviolet irradiation process, by controlling the UV irradiation temperature and UV irradiation intensity in combination, it is possible to obtain a liquid crystal film exhibiting different Bragg reflections. By controlling the UV irradiation temperature within the above range, the lyotropic liquid crystal properties of the cellulose derivative are expressed, making it easier to adjust the color to the target color and to obtain the desired color. By controlling the UV irradiation temperature within the above range and the UV irradiation intensity (preferably the UV irradiation time) within the above range, the color obtained by the UV irradiation temperature can be fixed, and a multicolor liquid crystal film exhibiting the desired color at the desired location can be obtained. A liquid crystal film of multiple colors (ie, a film exhibiting different Bragg reflections) can be easily obtained, for example, by using a photomask.

[0107] (Process for forming an alignment film on a substrate) The production of a liquid crystal film may include a step of forming an alignment film on a substrate (hereinafter referred to as an alignment film formation step), but the formation of an alignment film is not necessarily essential in the present disclosure. If an alignment film formation step is included, it may be included, for example, before the liquid crystal material application step. By forming an alignment film on a substrate, the alignment at the wavelength of Bragg reflection can be easily fixed in the heat treatment step or ultraviolet irradiation step.

[0108] By going through the above steps, a liquid crystal film can be obtained. The thickness of the liquid crystal film is not particularly limited. From the viewpoint of obtaining an excellent liquid crystal film, the thickness of the liquid crystal film is preferably 50 μm to 2000 μm, more preferably 100 μm to 1500 μm, and even more preferably 200 μm to 1000 μm. The liquid crystal film may be peeled off from the substrate before use, or may be used as it is formed on the substrate.

[0109] The liquid crystal film of the present disclosure can be mounted and used in, for example, optical films such as polarizing films, retardation films, backlights, anti-reflection films, light diffusion films, brightness enhancement films, and anti-glare films; sensors (pressure sensors, strain sensors, stretch sensors, vibration sensors, impact sensors, etc.) that detect deformation caused by strain, stretching, vibration, impact, etc. of an object using the wavelength of reflection (preferably the reflected color); wearable sensors that detect biological information such as pulse waves, respiration, and ballistocardiogram using the wavelength of reflection (preferably the reflected color); optical elements that use the above-mentioned optical films; optical elements other than those mentioned above; liquid crystal display elements; and the like.

[0110] The liquid crystal film of the present disclosure has both appropriate elasticity and flexibility, and when an external force (e.g., mechanical pressure) is applied, the film undergoes distortion, thereby enabling the generation of reflected light of a wavelength corresponding to the external force (e.g., mechanical pressure). In particular, the liquid crystal film of the present disclosure is a wet film containing a water-containing liquid, and is therefore suitable for use as a sensor for detecting biometric information such as fingerprints.

[0111] Furthermore, the liquid crystal film of the present disclosure is preferably used by being mounted on an optical element that utilizes reflected light that appears when distortion occurs due to the application of an external force (for example, mechanical pressure).

[0112] <Sensor> The sensor of the present disclosure includes the liquid crystal film of the present disclosure described above. The sensors of the present disclosure include pressure sensors, strain sensors, expansion / contraction sensors, vibration sensors, and impact sensors.

[0113] The sensor is preferably a strain sensor that detects strain in an object. The strain sensor includes the liquid crystal film of the present disclosure, and thus can detect deformation caused by strain occurring in an object by the wavelength of reflection (preferably the reflected color). For example, by pre-installing the strain sensor at a location on an object where strain is likely to occur (e.g., a structure such as a bridge or building), the degree of strain in the object can be detected. Furthermore, the strain sensor can visually detect an external force (e.g., mechanical pressure) caused by the strain (deformation), i.e., by the wavelength of reflection (preferably the reflected color).

[0114] The sensor is preferably a wearable sensor that detects biological information. A wearable sensor is a relatively small sensor that can be worn on the body. The wearable sensor includes the liquid crystal film of the present disclosure, and thus can detect biological information by the wavelength of reflection (preferably the color of reflection). For example, by attaching or wearing the strain sensor directly to the area where biological information is desired to be acquired (for example, the skin), or by attaching or wearing the strain sensor to clothing, underwear, socks, gloves, ties, handkerchiefs, scarves, watches, glasses, shoes, slippers, hats, etc., biological information (pulse wave, breathing, ballistocardiogram, body movement (muscle movement, etc.), etc.) can be acquired visually (i.e., by the wavelength of reflection (preferably the color of reflection)).

[0115] <Optical elements> The optical element of the present disclosure includes the sensor of the present disclosure described above. For example, by applying an external force (e.g., mechanical pressure) artificially or by installing an optical element in a location where an external force (e.g., mechanical pressure) is naturally applied, different reflected light can be obtained in response to the external force (e.g., mechanical pressure). Applications of such optical elements include toys, emergency light sources, interior decorations (figurines, shelves, etc.), building materials (floors, walls, stairs, etc.), tableware, containers, etc. [Example]

[0116] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples as long as it does not deviate from the gist of the invention. Unless otherwise specified, "parts" are based on mass.

[0117] (Synthesis of HPC derivatives) An HPC derivative having a crosslinkable group was synthesized by the following method. -Synthesis of HPC-AcC- Hydroxypropyl cellulose (HPC; Fujifilm Wako Pure Chemical Industries, Ltd., product name: Hydroxypropyl Cellulose 2.0-2.9, product number: 082-07925) containing the following structure (R: hydrogen atom or CH2CH(OR)CH3, n: repeating number) and having a molecular weight of 28,000 was prepared. The HPC was dried under reduced pressure (0.2 atmospheres) at room temperature (25°C) overnight (24 hours or more).

[0118] [ka]

[0119] Next, 3.0 g of HPC was weighed into a 200 mL recovery flask filled with nitrogen, and 15 mL of ultra-dehydrated acetone (Kanto Chemical Co., Ltd.) was added and mixed, and dissolved with stirring to obtain an HPC solution. In this case, the number of moles of hydroxy groups in the constitutional units derived from β-glucose monomers was calculated to be 23 mmol from the MS value (average number of hydroxypropyl groups per constitutional unit derived from β-glucose monomers).

[0120] The HPC solution was shielded from light with aluminum foil, and an appropriate amount (0.01 eq) of Karenz AOI (2-acryloyloxyethyl isocyanate (structure below), Showa Denko K.K.) was added at room temperature, followed by stirring for 5 days at room temperature in the dark.

[0121] [ka]

[0122] After stirring for 5 days, the acetone was removed using an evaporator and the mixture was dried to obtain the HPC derivative, HPC-AcC (degree of acryloyl carbamate (AcC; degree of hydroxyl group substitution) = 0.03). The yield of HPC-AcC was 2.9 g.

[0123] ( 1 H-NMR spectrum measurement) The HPC-AcC synthesized above 1 H-NMR spectrum was measured. Peaks derived from HPC-AcC include peaks of protons in the double bond of the acryloyl group at around 5.8 ppm, 6.1 ppm, and 6.4 ppm, a peak of the methine group of the terminal hydroxypropyl group at around 4.7 ppm to 5.2 ppm, and peaks of protons in the β-glucose monomer unit and of the methine group of the side chain hydroxypropyl group (proton peaks derived from the HPC skeleton) at around 2.7 ppm to 4.5 ppm. 1 From the H-NMR spectrum, the peaks at 4.7 ppm to 5.2 ppm are thought to be due to the protons of methine groups when the terminal hydroxypropyl groups are carbamate- or esterified, and to the protons of methine groups when the 2nd or 3rd position of the β-glucose monomer unit is carbamate- or esterified.

[0124] As a result, HPC-AcC is a compound in which the hydrogen atom of the hydroxyl group in the side chain of HPC is substituted with CH2=CH-C(=O)-O-(CH2)2-NHC(=O)- (acryloylethyl carbamate group). That is, HPC-AcC is a compound represented by the general formula (1A) in which R 11 , R 12 and R 13 A part of RNHCO-(R:CH2=CH-C(=O)-O-(CH2)2-) (the other part represents a hydrogen atom), and X 11 , X 12 and X 13 are each independently a single bond or (-CH2-CH(CH3)-O-) hIt is an HPC derivative having a molecular structure where [h=an integer of 1 to 10] and n11=70. The n11 (=70) structural units that make up HPC-AcC contained a mixture of several types with different structures.

[0125] Based on this peak, the degree of substitution of the acryloylethyl carbamate group (i.e., a group having an unsaturated double bond) in the HPC side chain (hydrogen atom in the hydroxyl group) was calculated. As a result, the degree of substitution of the acryloylethyl carbamate group (degree of substitution of the hydroxyl group) was 0.03.

[0126] -Synthesis of HPC-AcE- The HPC derivative HPC-AcE (degree of acryloyl esterification (AcE) = 0.03, 0.09; degree of hydroxyl group substitution) was obtained in the same manner as in the above "Synthesis of HPC derivative 1," except that Karenz AOI was replaced with the same amount of acryloyl chloride (structure shown below). The yield of HPC-AcE was 2.9 g. It should be noted that, for HPC-AcE, a derivative with AcE=0.09 was synthesized because a derivative with AcE=0.03 was not fixed by ultraviolet irradiation as described below, making it difficult to obtain a cured film.

[0127] [ka]

[0128] -Synthesis of HPC-MAcC- The HPC derivative, HPC-MAcC (degree of methacryloylcarbamation (MAcC) = 0.03; degree of hydroxyl group substitution) was obtained in the same manner as in the above "-Synthesis of HPC derivative 1-", except that Karenz AOI was replaced with the same amount of Karenz MOI (2-methacryloyloxyethyl isocyanate (structure below), Showa Denko K.K.). The yield of HPC-MAcC was 2.9 g.

[0129] [ka]

[0130] -Synthesis of HPC-bAcC- In the above "-Synthesis of HPC derivative 1-", Karenz AOI was replaced with the same amount of Karenz BEI (1,1-(bisacryloyloxymethyl)ethyl isocyanate (structure shown below), Showa Denko K.K.), and the HPC derivative, HPC-bAcC (degree of bisacryloylcarbamation (bAcC) = 0.03; degree of hydroxyl group substitution) was obtained in the same manner. The yield of HPC-bAcC was 2.9 g.

[0131] [ka]

[0132] (Example 1-1) <Fabrication of liquid crystal cells> -Preparation of liquid crystal film-forming composition 1- 2-hydroxy-4 ’ An aqueous initiator solution 1 was prepared by mixing 1 part by mass of -(2-hydroxyethoxy)-2-methylpropiophenone (HHEMPP; a water-soluble photopolymerization initiator having the structure shown below) with 600 parts by mass of water to dissolve HHEMPP in water. 64 parts by mass of the HPC-AcC synthesized above and 36 parts by mass of the initiator aqueous solution 1 were mixed to prepare a liquid crystal film forming composition 1-1.

[0133] [ka]

[0134] - Liquid crystal cell fabrication - At room temperature (25°C), the liquid crystal film-forming composition 1 obtained above was sandwiched between two commercially available slide glasses (substrates), and ultraviolet light (light source: mercury xenon lamp, optical filter: UV-35 / UV-D36A, wavelength: 365nm) was irradiated from both sides of the substrate for 10 minutes per side. In this way, a liquid crystal cell with a liquid crystal film of 500μm thickness was produced.

[0135] (Example 1-2) Next, a liquid crystal cell having a liquid crystal film with a thickness of 500 μm was prepared in the same manner as in Example 1-1, except that HPC-AcC was replaced with HPC-AcE (AcE=0.03).

[0136] (Examples 1-3) Next, a liquid crystal cell having a liquid crystal film with a thickness of 500 μm was prepared in the same manner as in Example 1-1, except that HPC-AcC was replaced with HPC-MAcC (MAcC=0.03).

[0137] (Examples 1-4) Next, a liquid crystal cell having a liquid crystal film with a thickness of 500 μm was prepared in the same manner as in Example 1-1, except that HPC-AcC was replaced with HPC-bAcC (bAcC=0.03).

[0138] <Measurement of transmission spectrum before and after UV irradiation> Using the liquid crystal cells prepared in Examples 1-1 to 1-4, the transmission spectra were measured before and after irradiating the liquid crystal cells with ultraviolet light (hereinafter referred to as UV light) at a wavelength of 365 nm for 10 minutes at room temperature (25°C). The measurement results are shown in Figure 1 (a), (c), (e), and (g). FIG. 1 shows the transmission spectra of the liquid crystal film in the liquid crystal cell before and after irradiation with UV light.

[0139] <Wavelength shift (hue change) during compression> The transmission spectrum of the liquid crystal film in the liquid crystal cell was measured under the following conditions. The thickness of the liquid crystal film in the liquid crystal cells prepared in Examples 1-1 to 1-4 was measured. Then, as shown in FIG. 17(A), the liquid crystal cell was set in a homemade compression tuning cell (see FIG. 17). The homemade compression tuning cell (see FIG. 17) can control the thickness of the liquid crystal film to within several hundred nanometers using three precision micrometer heads. The homemade compression tuning cell (see FIG. 17) was used to compress the liquid crystal cell in the thickness direction by 30 μm increments, applying strain to the liquid crystal film. A compact fiber multichannel spectrometer (manufactured by Ocean Optics, model number: USB-4000) was used to measure the transmission spectrum every 30 μm, thereby measuring the wavelength shift change upon compression. Specifically, the compact fiber multichannel spectrometer includes a white light source unit and a detection unit. The white light source unit and the detection unit are arranged so that the compression tuning cell is located between the white light source unit and the detection unit. Specifically, the white light source unit is located on the precision micrometer head side (upper side in Figure 17(A)) of the liquid crystal film set in the compact fiber multichannel spectrometer. The detection unit is located on the opposite side of the precision micrometer head side (lower side in Figure 17(A)) of the liquid crystal film set in the compact fiber multichannel spectrometer. The white light source unit is a general halogen light source that emits light over a wide wavelength range from approximately 360 nm to 2.4 μm. The detection unit detects the light emitted from the white light source unit that has passed through a liquid crystal cell set in a homemade compression tuning cell. This resulted in the observation of the transmission spectrum of a liquid crystal film controlled to a specific film thickness. The measurement results are shown in Figures 2 to 5 (a) and (c). The liquid crystal film is circular, with a diameter of 4 mm and a thickness of 500 μm, and its initial area is 4π mm 22 to 5 show the transmission spectra of liquid crystal films using HPC-AcC, HPC-AcE, HPC-bAcC, or HPC-MAcC during the compression process before and after drying and curing. Drying and curing was performed at room temperature for 24 hours. More specifically, each of Figs. 2 to 5 is a superimposition of measured transmission spectra of liquid crystal films when the thickness of the liquid crystal film was set to 500 μm (uncompressed), 470 μm, 440 μm, 410 μm, 380 μm, 350 μm, 320 μm, 290 μm, 260 μm, 230 μm, 200 μm, or 170 μm using a compression tuning cell (see Fig. 17). 2 to 5, "ε=0" indicates no distortion in the liquid crystal film, "ε=0.2" indicates distortion in the liquid crystal film when the liquid crystal film thickness is set to 170 μm, and the arrows indicate wavelength shifts.

[0140] <Film strength when released (SS curve)> The change in film strength before and after drying and hardening when the compressed state in the above "wavelength shift change upon compression" was released was measured using the following method, and an SS curve was created. The liquid crystal film was compressed using a compression and tension tester (Shimadzu Corporation, Model: Autograph AGS-X) with a load cell load of 1000 N and a compression rate of 0.5 mm / min until the strain (ε) of the liquid crystal film reached 0.2. The liquid crystal film was then released without applying any compressive force until the strain (ε) of the liquid crystal film reached 0. The film strength was continuously measured using the compression and tension tester (Shimadzu Corporation, Model: Autograph AGS-X). The results are shown in Figure 7(a) and (c). Figure 7 shows the SS curves for compression and release. Figure 7(a) shows the film strength of the liquid crystal film before drying. Figure 7(c) shows the film strength of the liquid crystal film after drying.

[0141] Example 2-1 <Fabrication of liquid crystal cells> -Preparation of liquid crystal film-forming composition 1- An aqueous solution of HHEMPP in water was prepared by mixing 1 part by mass of HHEMPP with 600 parts by mass of water, and this was further mixed with 150 parts by mass of glycerin (water:glycerin [mass ratio] = 80:20) to prepare initiator aqueous solution 2. 64 parts by mass of the HPC-AcC synthesized above and 36 parts by mass of the initiator aqueous solution 2 were mixed to prepare a liquid crystal film-forming composition 2-1.

[0142] - Liquid crystal cell fabrication - A liquid crystal cell having a liquid crystal film with a thickness of 500 μm was prepared in the same manner as in Example 1-1, except that the liquid crystal film forming composition 1-1 in Example 1-1 was replaced with the liquid crystal film forming composition 2-1.

[0143] (Example 2-2) Next, a liquid crystal cell having a liquid crystal film with a thickness of 500 μm was prepared in the same manner as in Example 2-1, except that HPC-AcC was replaced with HPC-AcE (AcE=0.09).

[0144] (Example 2-3) Next, a liquid crystal cell having a liquid crystal film with a thickness of 500 μm was prepared in the same manner as in Example 2-1, except that HPC-AcC was replaced with HPC-MAcC (MAcC=0.03).

[0145] (Examples 2-4) Next, a liquid crystal cell having a liquid crystal film with a thickness of 500 μm was prepared in the same manner as in Example 2-1, except that HPC-AcC was replaced with HPC-bAcC (bAcC=0.03).

[0146] <Measurement of transmission spectrum before and after UV irradiation> Using the liquid crystal cells prepared in Examples 2-1 to 2-4, the transmission spectra were measured before and after irradiating the liquid crystal cells with ultraviolet (UV) rays at a wavelength of 365 nm for 10 minutes at room temperature (25°C). The measurement results are shown in Figure 1 (b), (d), (f), and (h).

[0147] <Wavelength shift (hue change) during compression> The wavelength shift change when the liquid crystal film in the liquid crystal cells prepared in Examples 2-1 to 2-4 was compressed was measured in the same manner as in Example 1-1, etc. The measurement results are shown in (b) and (d) of Figures 2 to 5, respectively.

[0148] <Strain> For the liquid crystal cells prepared in Examples 2-1 to 2-4, the strain of the liquid crystal film after drying was measured by applying mechanical pressure to both sides of the liquid crystal cell using a homemade compression tuning cell (see Figure 17), which can control the film thickness of the liquid crystal film to within several hundred nanometers using three precision micrometer heads. The ratio of the wavelength λ after compression to the wavelength λ0 before compression by mechanical pressure (λ / λ0; normalized wavelength) was plotted against the strain of the liquid crystal film after drying, and a regression line was obtained. The results are shown in Figure 6. FIG. 6 is a correlation diagram showing the relationship between the normalized wavelength and the strain in the compression process after drying of a liquid crystal film containing glycerin and water.

[0149] <Film strength when released (SS curve)> The change in film strength before and after drying and curing when the compressed state in the above "wavelength shift change upon compression" was released was measured in the same manner as in Example 1-1, and an SS curve was created. Drying and curing was performed in the same manner as in the above-mentioned "wavelength shift change (hue change) upon compression." The measurement results are shown in Figure 7(b) and (d). Figure 7(b) shows the film strength of the liquid crystal film before drying and curing. Figure 7(d) shows the film strength of the liquid crystal film after drying and curing.

[0150] (Consideration 1) The liquid crystal cells prepared in Examples 1-1 to 1-4 and 2-1 to 2-4 were measured for transmittance in the wavelength range of 400 nm to 900 nm before and after UV irradiation, and the transmittance spectra shown in Figure 1 were obtained. As can be seen from Figure 1, in the liquid crystal film using HPC-AcC, no significant changes were observed with or without the addition of glycerin, or before and after UV curing. On the other hand, in the liquid crystal films using HPC-AcE, HPC-bAcC, or HPC-MAcC, almost no changes were observed before and after UV curing, but the addition of glycerin significantly reduced the transmittance, and it was found that the absorption peak shifted from the near-infrared region of 800 nm or more to the visible light region of around 600 nm to 750 nm.

[0151] Next, Figures 2 to 5 show the transmission spectra of liquid crystal films made with various HPC derivatives (HPC-AcC, HPC-AcE, HPC-bAcC, or HPC-MAcC) with different unsaturated double bond groups (crosslinkable groups) during compression before and after drying. For example, comparing Figures 2(a) and 2(c), the magnitude of the arrow (vector) in Figure 2(c) is smaller than that in Figure 2(a). Therefore, for all liquid crystal films, the wavelength shift (hue change) when the compression strength is changed by drying and volatilizing the water is reduced. Furthermore, the wavelength shift due to compression after drying is larger for liquid crystal films containing both glycerin and water than for liquid crystal films containing only water.

[0152] Furthermore, Figure 6 shows the correlation between normalized wavelength and strain during the compression process after drying of liquid crystal films containing glycerin and water. As shown in Figure 6, the slope of the normalized wavelength versus strain for the HPC-AcC liquid crystal film is larger than those for the HPC-bAcC, HPC-MAcC, and HPC-AcE liquid crystal films. Therefore, as is clear from Figure 6, HPC-AcC exhibits the largest wavelength shift during the compression process after drying. The more sensitive and noticeable a liquid crystal film is when subjected to an external force, the more suitable it is for practical use (such as in sensors).

[0153] Figure 7 shows the SS curves of the compression-release process before and after drying for liquid crystal films made with each HPC derivative (HPC-AcC, HPC-AcE, HPC-bAcC, or HPC-MAcC) with different crosslinking groups, with and without glycerin. Figure 7(a) and (b) show the strength of the film before drying. Figure 7(c) and (d) show the strength of the film after drying. The stress of each liquid crystal film was less than 1 MPa in Figures 7(a) and 7(b), whereas it was more than 2 MPa in Figures 7(c) and 7(d). Therefore, it was confirmed that all liquid crystal films hardened when dried. Comparing the liquid crystal films containing only water and those containing glycerin and water, there was no significant difference between the two before drying, as shown in Figures 7(a) and 7(b), but differences were observed after drying, as shown in Figures 7(c) and 7(d). Furthermore, the stress of the liquid crystal films of HPC-MAcC, HPC-bAcC, and HPC-AcC after drying was less than 4 MPa in Figure 7(d), whereas it exceeded 4 MPa in Figure 7(c). Furthermore, the stress of the liquid crystal film of HPC-AcE after drying was less than 2 MPa in Figure 7(d), whereas it exceeded 2 MPa in Figure 7(c). This indicates that, regardless of the HPC derivative, the liquid crystal films containing glycerin and water were softer than those containing only water. The softening of the film is considered to be important from the viewpoint of obtaining a liquid crystal film in which the change in the external force is sensitively and remarkably reflected as a change in color. From this viewpoint, it was demonstrated that a liquid crystal film containing glycerin in addition to water is useful as a lyotropic cholesteric liquid crystal material.

[0154] Example 3 HPC-AcCs with different degrees of acryloylcarbamation were synthesized in the same manner as in the above "-Synthesis of HPC-AcC-" except that the degree of acryloylcarbamation (AcC; degree of hydroxyl group substitution) in HPC-AcC was changed from 0.03 to 0.15 and 0.31. Then, in Examples 1-1 and 2-1, liquid crystal cells having liquid crystal films using three types of HPC-AcC with AcC = 0.03, 0.15, and 0.31 were prepared.

[0155] <Measurement of transmission spectrum before and after UV irradiation> Using the above three types of liquid crystal cells, the liquid crystal cells were irradiated with ultraviolet (UV) light at a wavelength of 365 nm for 10 minutes at room temperature (25°C), and the transmission spectra were measured before and after. The measurement results are shown in Figure 8. FIG. 8 shows the transmission spectra of the liquid crystal film in each liquid crystal cell before and after UV light irradiation.

[0156] <Wavelength shift (hue change) during compression> The wavelength shift change upon compression of liquid crystal films using three types of HPC-AcC with AcC=0.03, 0.15, and 0.31 was measured in the same manner as in Example 1-1.

[0157] <Strain> For the above three types of liquid crystal cells, the strain of the liquid crystal film after drying was measured and a regression line was determined in the same manner as in Example 2-1, etc. The results are shown in FIG. FIG. 9 shows the correlation between the normalized wavelength and strain during the compression process after drying of liquid crystal films (water:glycerin=80:20) using HPC-AcC with different amounts of AcC introduced.

[0158] <Film strength when released (SS curve)> The change in film strength before and after drying and hardening when the compressed state in the above "wavelength shift change upon compression" was released was measured in the same manner as in Example 1-1, and an SS curve was created. The measurement results are shown in Figure 10.

[0159] (Consideration 2) As shown in Figure 8, although there is almost no change before and after UV curing, the transmittance drops significantly when glycerin is added, and the absorption peak shifts from the near-infrared region with a wavelength of 800 nm or more to the visible light region with a wavelength of around 600 nm to 750 nm.

[0160] Although the transmission spectra during the compression process before and after drying of the liquid crystal film are not shown, similar to Figure 2, the wavelength shift due to compression after drying was larger for the liquid crystal film containing glycerin and water after drying than for the liquid crystal film containing only water after drying. 9, HPC-AcC with AcC=0.31 has a significant effect of improving wavelength shift during the compression process after drying compared to other HPC-AcCs. Among the three types of liquid crystal cells mentioned above, the liquid crystal cell having a liquid crystal film using HPC-AcC with AcC=0.31 is preferred.

[0161] Figure 10 shows the SS curves of the compression-release process before and after drying for three types of liquid crystal films using HPC-AcC with different amounts of AcC (water:glycerin = 80:20). Figure 10 (a) and (b) show the strength of the film before drying. As shown in Figure 10(a) and (b), the stress of the HPC-AcC liquid crystal film was lower at AcC = 0.03 than at AcC = 0.15, and AcC = 0.15 was lower than at AcC = 0.31. Therefore, Figure 10 shows that the liquid crystal film containing only water and the liquid crystal film containing glycerin and water become harder as the amount of AcC introduced increases before drying. Furthermore, after drying, although no significant difference was observed between the two, the stress decreased as the amount of AcC introduced increased, indicating that a softer film was obtained.

[0162] Example 4 In Examples 1-1 and 2-1, three types of liquid crystal cells with different HPC-AcC content concentrations were prepared in the same manner as in Examples 1-1 and 2-1, except that the content ratio of HPC-AcC used to prepare liquid crystal film-forming composition 1-1 was changed from 64 parts by mass (64 mass%) to 66 mass%, 68 mass%, or 70 mass%.

[0163] <Measurement of transmission spectrum before and after UV irradiation> Using the above three types of liquid crystal cells, the liquid crystal cells were irradiated with ultraviolet (UV) light at a wavelength of 365 nm for 10 minutes at room temperature (25°C), and the transmission spectra were measured before and after. The measurement results are shown in Figures 11A, 11B, and 11C. 11A, 11B, and 11C show the transmission spectra of liquid crystal films with different HPC-AcC concentrations before and after UV light irradiation.

[0164] <Wavelength shift (hue change) during compression> The wavelength shift change of the liquid crystal film in the above three types of liquid crystal cells when compressed was measured in the same manner as in Example 1-1.

[0165] <Strain> For the above three types of liquid crystal cells, the strain of the liquid crystal film after drying was measured and a regression line was determined in the same manner as in Example 2-1, etc. The results are shown in FIG. Figure 12 shows the correlation between the normalized wavelength and strain during the compression process after drying of liquid crystal films (water:glycerin=80:20) with different HPC-AcC concentrations.

[0166] <Film strength when released (SS curve)> The change in film strength before and after drying and hardening when the compressed state in the above "wavelength shift change upon compression" was released was measured in the same manner as in Example 1-1, etc., and an SS curve was created. The measurement results are shown in Figure 13.

[0167] (Consideration 3) 11A, 11B, and 11C, it can be seen that the higher the concentration of the polymer HPC-AcC, the more the peak wavelength shifts to the shorter wavelength side. The peak wavelength refers to the wavelength at which the transmittance is minimal in FIGS. 11A to 11C. Furthermore, the addition of glycerin further shifts the peak wavelength to the shorter wavelength side.

[0168] Although the transmission spectra during the compression process before and after drying of the liquid crystal film are not shown, similar to Figure 2, the liquid crystal film containing glycerin and water showed a larger wavelength shift due to compression after drying than the liquid crystal film containing only water. Furthermore, as is clear from Figure 12, the liquid crystal cell with a low concentration of HPC-AcC exhibits a significant improvement in wavelength shift during the compression process after drying compared to other liquid crystal cells. This is thought to be due to the concentration of glycerin remaining in the film after drying. Of the three types of liquid crystal cells mentioned above, the liquid crystal cell with an HPC-AcC concentration of 66% by mass is preferred.

[0169] Figure 13 shows the SS curves of the liquid crystal film (water:glycerin = 80:20) with different HPC-AcC concentrations during the compression-release process before and after drying for three types of liquid crystal cells. As can be seen from Figure 13, the higher the HPC-AcC concentration, the harder the liquid crystal film, and this tendency was maintained even after drying.

[0170] Example 5 Four types of liquid crystal cells with different glycerin concentrations were prepared in the same manner as in Example 2-1, except that the mixing ratio of glycerin used to prepare the liquid crystal film-forming composition 2-1 was changed from 20% by mass to 0%, 10%, 30%, or 40% by mass. Then, the following measurements and evaluations were performed using five types of liquid crystal cells with different glycerin concentrations (glycerin mixing ratio = 0%, 10%, 20%, 30%, and 40% by mass).

[0171] <Measurement of transmission spectrum before and after UV irradiation> Using the above five types of liquid crystal cells, the liquid crystal cells were irradiated with ultraviolet (UV) light at a wavelength of 365 nm for 10 minutes at room temperature (25° C.), and the transmission spectra were measured before and after the irradiation. The measurement results are shown in FIG. FIG. 14 shows the transmission spectra of liquid crystal films containing different concentrations of glycerin before and after UV light irradiation.

[0172] <Wavelength shift (hue change) during compression> The wavelength shift change of the liquid crystal film in the above three types of liquid crystal cells when compressed was measured in the same manner as in Example 1-1.

[0173] <Strain> For the above five types of liquid crystal cells, the strain of the liquid crystal film after drying was measured and a regression line was determined in the same manner as in Example 2-1, etc. The results are shown in FIG. FIG. 15 shows the correlation between the normalized wavelength and strain during the compression process after drying of liquid crystal films containing different concentrations of glycerin (water:glycerin=80:20).

[0174] <Film strength when released (SS curve)> The change in film strength before and after drying and hardening when the compressed state in the above "wavelength shift change upon compression" was released was measured in the same manner as in Example 1-1, etc., and an SS curve was created. The measurement results are shown in Figure 16.

[0175] (Consideration 4) As is clear from Figure 14, the peak wavelength shifts to the shorter wavelength side as the glycerin concentration increases. This is thought to be because the density of glycerin is greater than that of water, so the helical pitch cannot expand. When the glycerin content reached 50% by mass (water:glycerin = 50:50), the viscosity of the liquid crystal film-forming composition increased significantly. At a water:glycerin ratio of 60:40, the transmittance of the liquid crystal film was approximately 40%. Therefore, the glycerin content is preferably in the range of 45% by mass or less.

[0176] Although the transmission spectra during the compression process before and after drying of the liquid crystal film are not shown, similar to Figure 2, the liquid crystal film containing glycerin and water showed a larger wavelength shift due to compression after drying than the liquid crystal film containing only water. Furthermore, as is clear from Figure 15, the higher the glycerin concentration, the more pronounced the improvement in wavelength shift during the compression process after drying. This is thought to depend on the concentration of glycerin remaining in the film after drying. The wavelength shift during the compression process after drying became steeper when the glycerin concentration was 20 mass% or higher, and the wavelength shift (hue change) tended to gradually increase as the glycerin concentration increased.

[0177] Figure 16 shows the SS curves of the liquid crystal films with different glycerin concentrations (glycerin ratio = 0% by mass to 40% by mass) in the compression-release process before and after drying for five types of liquid crystal cells. As can be seen from Figure 16, the higher the glycerin concentration, the softer the liquid crystal film obtained after drying.

[0178] Example 6 A liquid crystal cell having a liquid crystal film was prepared in the same manner as in Example 1-1. The size of the liquid crystal film was 2 cm in diameter and 500 μm in thickness. The liquid crystal cell was subjected to a drying treatment to obtain a dried liquid crystal film (hereinafter referred to as "first elastic film") using HPC-AcC containing only water. The drying treatment was carried out in the same manner as in the drying and curing in the above-mentioned <Shift in wavelength (hue change) upon compression>. When the main surface (diameter: 2 cm) of the first elastic film was visually observed, the color of the main surface of the first elastic film was a uniform light blue overall. The surface of the elastic membrane was divided into two sections, the first section and the second section, so that the surface area of ​​the first elastic membrane was half that of the first elastic membrane, and the entire first section was covered with vinyl tape to obtain the second elastic membrane. In the second elastic membrane, the first section was not exposed, and the second section was exposed. The second elastic film and absorbent cotton soaked in water were placed in a polystyrene case, and the case was left sealed at room temperature (25°C) for 2 hours. In other words, the second region of the second elastic film was allowed to absorb moisture. This resulted in the production of a third elastic film. The vinyl tape was removed from the third elastic membrane to obtain a fourth elastic membrane. In the fourth elastic membrane, the water content in the first region was relatively low, while the water content in the second region was relatively high. Visual observation of the main surface of the fourth elastic membrane revealed that the color of the first region of the fourth elastic membrane was a uniform light blue overall, similar to the color of the main surface of the first elastic membrane. The color of the second region of the fourth elastic membrane was a uniform yellow-green overall, different from the color of the main surface of the first elastic membrane. The fourth elastic film was heated in a microwave oven at 500W for 30 seconds. In other words, the entire fourth elastic film was dried. This drying method may be reduced pressure drying for 2 hours. This resulted in a fifth elastic film. The main surface of the fifth elastic film was photographed using an imaging spectroscopic system (a mirror scan spectroscopic scanner device manufactured by JFE Techno Research Corporation) equipped with a hyperspectral camera (manufactured by SPECIM, model number: ImSpector V8C). Figure 18(a) is a photograph (magnification: 1x) of the reflected image of the main surface of the fifth elastic film. When the main surface of the fifth elastic film was visually observed, the color of the main surface of the fifth elastic film was a uniform light blue overall, similar to the color of the main surface of the first elastic film, as shown in Figure 18(a). No color difference was observed at the boundary between the first and second regions of the fifth elastic film. A portion of the main surface (4 mm diameter surface) of the fifth elastic membrane was covered with vinyl tape cut into the shape of the letter "T" (hereinafter referred to as "T-shaped masking tape") to obtain a sixth elastic membrane. In the sixth elastic membrane, the exposed portion not covered by the T-shaped masking tape (hereinafter referred to as "T-shaped exposed portion") formed a T shape and spanned the first and second regions. The sixth elastic membrane and absorbent cotton soaked in water were placed in a polystyrene case, and the case was left sealed at room temperature (25°C) for 2 hours. In other words, the exposed T-shaped portion of the sixth elastic membrane was allowed to absorb moisture. This resulted in the seventh elastic membrane. The T-shaped masking tape was removed from the seventh elastic membrane to obtain the eighth elastic membrane. The main surface of the eighth elastic membrane was photographed using an imaging spectroscopy system (JFE Techno Research Corporation, mirror scan type spectroscopic scanner) equipped with a hyperspectral camera (SPECIM, model number: ImSpector V8C). Figure 18(b) is a photograph of the reflected image of the main surface of the eighth elastic membrane (photographed at 1x magnification). In the eighth elastic membrane, the water content in the area covered with the T-shaped masking tape was relatively low, while the water content in the exposed T-shaped area was relatively high. Visual observation of the main surface of the eighth elastic membrane revealed that the color of the area covered with the T-shaped masking tape was light blue, similar to the color of the main surface of the first elastic membrane. The color of the exposed T-shaped area of ​​the eighth elastic membrane was a uniform yellow-green overall, different from the color of the main surface of the first elastic membrane. No difference in color was observed at the boundary between the color of the first area of ​​the T-shaped exposed part of the eighth elastic membrane and the color of the second area of ​​the T-shaped exposed part of the eighth elastic membrane. The rewriting cycle from the first elastic membrane to the eighth elastic membrane could be repeated at least 20 times.

[0179] In addition, using an imaging spectroscopy system (a mirror-scanning spectroscopic scanner device manufactured by JFE Techno-Research Corporation) equipped with a hyperspectral camera (Specim, model number: ImSpector V8C), the reflection spectra of each region of the liquid crystal film using HPC-AcC were measured. Specifically, the reflection spectra of the center P1 of the main surface of the fifth elastic film (see Figure 18(a)"), the edge P2 of the main surface of the fifth elastic film (see Figure 18(a)"), the center P1 of the main surface of the eighth elastic film (see Figure 18(b)), and the edge P2 of the main surface of the eighth elastic film (see Figure 18(b)) were measured. The center P1 of the main surface of the eighth elastic film was the exposed portion. The edge P2 of the main surface of the eighth elastic film was the portion covered with T-shaped masking tape. The measurement results are shown in Figure 19. In detail, Figure 19(a) shows the measurement results of the reflection spectrum of the center P1 of the main surface of the fifth elastic membrane (see Figure 18(a)). Figure 19(b) shows the measurement results of the reflection spectrum of the center P1 of the main surface of the eighth elastic membrane (see Figure 18(b)). Figure 19(c) shows the measurement results of the reflection spectrum of the edge P2 of the main surface of the fifth elastic membrane (see Figure 18(a)). Figure 19(d) shows the measurement results of the reflection spectrum of the edge P2 of the main surface of the eighth elastic membrane (see Figure 18(b)).

[0180] As shown in Figure 19(a), the wavelength at which the reflectance of the central portion P1 of the fifth elastic film before moisture absorption was maximum was 451 nm, whereas as shown in Figure 19(d), the wavelength at which the reflectance of the central portion P1 of the eighth elastic film after moisture absorption was maximum was 528 nm. In other words, by absorbing moisture into the fifth elastic film, the wavelength at which the reflectance was maximum shifted to a longer wavelength by about 77 nm. As shown in Figure 19(c), the wavelength at which the reflectance of edge P2 of the fifth elastic film before moisture absorption was maximum was 449 nm, whereas as shown in Figure 19(b), the wavelength at which the reflectance of edge P2 of the eighth elastic film after moisture absorption was maximum was 459 nm. In other words, because edge P2 was covered with T-shaped masking tape, the wavelength at which the reflectance was maximum hardly changed.

[0181] These results indicate that partial moisture absorption of a dried liquid crystal film using HPC-AcC containing only water makes it easier to pattern than conventional methods, and that rewriting is easily possible by drying the patterned liquid crystal film. Conventionally, patterning is performed by heating the liquid crystal film and irradiating designated areas of the liquid crystal film with ultraviolet light.

Claims

1. a hydroxyalkyl cellulose in which some of the hydroxyl groups are substituted with groups having an unsaturated double bond; A liquid containing water; Contains The concentration of the hydroxyalkyl cellulose is 60% by mass or more based on the total mass of the liquid crystal film-forming composition; the liquid further contains a polar solvent other than water, The liquid crystal film-forming composition, wherein the polar solvent contains glycerin.

2. a hydroxyalkyl cellulose in which some of the hydroxyl groups are substituted with groups having an unsaturated double bond; A liquid containing water; Contains the liquid further contains a polar solvent other than water, The liquid crystal film forming composition, wherein the polar solvent contains glycerin.

3. 3. The composition for forming a liquid crystal film according to claim 1, wherein the liquid contains glycerin in a ratio of 5% by mass to 45% by mass relative to the total content of water and glycerin.

4. A hydroxyalkyl cellulose in which some of the hydroxyl groups are substituted with groups having an unsaturated double bond; A liquid containing water; Contains The concentration of the hydroxyalkyl cellulose is 60% by mass or more based on the total mass of the liquid crystal film-forming composition; A liquid crystal film-forming composition used to form a lyotropic liquid crystal film.

5. The composition for forming a liquid crystal film according to any one of claims 1 to 4, wherein the hydroxyalkyl cellulose has a degree of substitution of hydroxyl groups calculated by the following formula 1 of 0.01 to 0.4: Formula 1: Degree of substitution of hydroxyl group = total number of groups having unsaturated double bonds present per monomer unit / 3

6. The hydroxyalkyl cellulose has a structural unit represented by the following general formula (1A), and the degree of substitution of hydroxyl groups calculated by the following formula (2) is 0.01 to 0.4, the composition for forming a liquid crystal film according to any one of claims 1 to 5. Formula 2: Degree of substitution of hydroxyl group = R １１ , R １２ and R １３ Total number of groups having unsaturated double bonds in / 3 【Chemistry 1】 In the formula, X １１ , X １２ and X １３ are each independently a single bond, an alkylene group, -(R １４ -O) ｈ - or -C(=O)-R １５ represents -, and R １１ , R １２ and R １３ each independently represents a hydrogen atom or a group having an unsaturated double bond, R １４ and R １５ each independently represents an alkylene group, h represents an integer of 1 or more and 10 or less, and n11 represents an integer of 2 or more and 800 or less.

7. 7. The composition for forming a liquid crystal film according to claim 1, wherein the hydroxyalkyl cellulose is hydroxypropyl cellulose.

8. The liquid crystal film forming composition according to claim 6 or 7, wherein the group having an unsaturated double bond is a group derived from at least one compound selected from the group consisting of acryloyl halide, 2-acryloyloxyethyl isocyanate, 2-methacryloyloxyethyl isocyanate, 1,1-(bisacryloyloxymethyl)ethyl isocyanate, and acrylic anhydride.

9. 9. The composition for forming a liquid crystal film according to claim 6, wherein the group having an unsaturated double bond is a group derived from 2-acryloyloxyethyl isocyanate.

10. The composition for forming a liquid crystal film according to any one of claims 1 to 3, which is used for forming a lyotropic liquid crystal film.

11. A liquid crystal film which is a crosslinked product of the liquid crystal film-forming composition according to any one of claims 1 to 10.

12. A sensor having a liquid crystal film as described in claim 11.

13. An optical element equipped with the sensor described in claim 12.

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