JP6782485B2 - Liquid crystal materials, liquid crystal films and their manufacturing methods, sensors, and optical elements - Google Patents

Description

The present invention relates to a liquid crystal material, a liquid crystal film and a method for producing the same, a sensor, and an optical element.

Liquid crystal materials are not limited to display materials for liquid crystal displays, but in recent years, their optical characteristics have been utilized to promote their adaptation to photonic devices. Cellulose derivatives are known as one of the liquid crystal materials.
For example, Patent Document 1 discloses a cellulose derivative having a liquid crystal property in which a substituent having a carbamate group (urethane bond) is introduced into a hydrogen atom of a hydroxyl group of hydroxypropyl cellulose.
Further, Patent Document 2 describes a step (I) of mixing a solvent (A), a cellulose derivative (B) capable of forming a liquid crystal in the solvent (A), and a tetraalkoxysilane (C) to obtain a mixed solution. ), The liquid crystal product in the composite material by the step (II) of obtaining the composite material of the liquid crystal product of the cellulose derivative (B) and the condensate of the tetraalkoxysilane (C), and the treatment of the acid (E). A method for producing a silica-based chiral structure, which comprises the step (III) of removing the above-mentioned material, is disclosed.
In recent years, it has been reported that a chitosan derivative as a cellulose derivative exhibits cholesteric liquid crystallinity.

JP-A-2015-48365 JP-A-2016-113315

Biomacromolecules, Vol. 10, No. 1,2009,166-173

The above-mentioned Patent Document 1 describes that a carbamate group (-CONH-) may be introduced and a methacryloyl group may be introduced into the hydrogen atom of the hydroxyl group of hydroxypropyl cellulose. The group was not introduced to crosslink between the monomeric units of the cellulose derivative. Furthermore, Patent Document 1 does not plan to impart elasticity to the crosslinked cellulose derivative.
Further, Patent Document 2 described above discloses that in order to obtain a silica-based chiral structure, the liquid crystal product of the cholesteric liquid crystal formed by the cellulose derivative (B) is immobilized by the step (II). There is. However, since this liquid crystal product is finally removed by the treatment with an acid, the silica-based chiral structure does not utilize the liquid crystal property and optical properties of cellulose. Further, research on the liquid crystallinity of the chitosan derivative described in Non-Patent Document 1 described above is currently underway.
Cellulose derivatives having liquid crystal properties as described above (liquid crystal materials using cellulose derivatives in Patent Document 2) are known, but the properties (liquid crystal properties, optical properties, etc.) of the cellulose derivatives are further extracted and drawn out. It would be useful if these properties could be utilized in the development of liquid crystal materials, liquid crystal films, and photonic devices.
In addition, cellulose is a material that is harmless to the human body and the environment, and is an inexpensive material because it is the most abundant raw material in nature.
Therefore, the development of the liquid crystal material or the like using cellulose as a raw material is also useful from the viewpoint of safety and the viewpoint of reducing the environmental load.

The present invention has been made in view of the above circumstances.
That is, an object of the present invention is a liquid crystal material containing a cellulose derivative, which can produce a liquid crystal film exhibiting thermotropic cholesteric liquid crystal property, having elasticity, and having an orientation fixed at a wavelength of Bragg reflection. It is to provide a liquid crystal material.
An object of the present invention is to provide a liquid crystal film having elasticity and whose orientation is fixed at the wavelength of Bragg reflection, and a method for producing the liquid crystal film.
An object of the present invention is to provide a sensor capable of detecting a mechanical stress corresponding to a wavelength of reflection (preferably a reflection color) according to the wavelength of reflection (preferably a reflection color).
An object of the present invention is to provide an optical element capable of obtaining reflected light having a wavelength corresponding to the stress by applying a mechanical stress.

As a result of diligent studies by the present inventors, a liquid crystal material containing a cellulose derivative having a molecular structure represented by the following general formula (1A) or the following general formula (1B) exhibits thermotropic cholesteric liquid crystal properties and is crosslinked. By doing so, it was found that the elasticity can be exhibited and the orientation can be fixed at the wavelength of Bragg reflection to develop a color, and the present invention has been completed.
That is, the means for solving the above-mentioned problems includes the following embodiments.
<1> A cellulose derivative having a molecular structure represented by the following general formula (1A) or the following general formula (1B) is contained.
The average number of hydroxyl groups per monomer unit is 0.3 or less.
A liquid crystal material having a degree of substitution per monomer unit of a group having an unsaturated double bond of 0.01 or more and 2.0 or less.

(In the general formula ^{(1A), X 11, X} 12 and ^{X 13} each independently represent a single bond, an alkylene _{^{group, - (R 14 -O) h}} -, ^{or, -C (= O) -R 15} - R ¹¹ , R ¹² and R ¹³ each independently represent a hydrogen atom, a group having an unsaturated double bond or a hydrophobic group, and R ¹⁴ and R ¹⁵ each independently represent 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.)

(In the general formula ^{(1B), X 16} and ^{X 17} each independently represent a single bond, an alkylene _{^{group, - (R 18 -O) i}} -, ^{or, -C (= O) -R 19} - represents, R ¹⁶ and R ¹⁷ each independently represent a hydrogen atom, a group having an unsaturated double bond, or a hydrophobic group, R ¹⁸ and R ¹⁹ are independently alkylene groups, and L ¹ is , An alkyl group, i represents an integer of 1 or more and 10 or less, and n12 represents an integer of 2 or more and 800 or less.)
<2> The ratio of the degree of substitution of the unsaturated double bond per monomer unit to the degree of substitution of the hydrophobic group per monomer unit (the group having the unsaturated double bond / the hydrophobic group). ) Is 3.0 × 10 ^-3 or more and 2.0 or less, according to <1>.
<3> The liquid crystal material according to <1> or <2>, wherein the molecular structure represented by the general formula (1A) is a molecular structure represented by the following general formula (1A-1).

(In the general formula (1A-1), R ¹ represents -CH _2- CH _2- or -CH _2- CH (CH ₃ )-, and R ¹¹ , R ¹² and R ¹³ are independent of each other. , Hydrogen atom, a group having an unsaturated double bond, or a hydrophobic group, m1, t1 and r1 independently represent an integer of 0 or more and 10 or less, and n13 is an integer of 2 or more and 800 or less. Represents.)
<4> The group having an unsaturated double bond is a group represented by the following general formula (1C).
The hydrophobic group is 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, and a carbon number of carbon atoms. A linear or branched acyl group of 2 to 18, a linear or branched alkoxy group having 1 to 18 carbon atoms, a carboxylic acid ester group represented by −COOR ^1A , or a halogen atom, wherein R ^1A is a carbon. Described in any one of <1> to <3>, which is a linear or branched alkyl group having the number 1 to 12, a cycloalkyl group having 3 to 12 carbon atoms, or an aryl group having 6 to 12 carbon atoms. Liquid crystal material.

(In the general formula (1C), R ^1C represents a hydrogen atom or a methyl group, X ¹⁸ is a single bond, a linear or branched alkylene group having 1 to 18 carbon atoms, and a cycloalkylene group having 3 to 18 carbon atoms. , An arylene group having 6 to 18 carbon atoms, or a linking group in which one or two or more selected from the group consisting of -O-, -NH-, -S-, and -C (= O)-is linked. Represented, p1 represents an integer of 1 or 2. However, the valence of X ¹⁸ is p1 + 1. ** is combined with X ¹¹ , X ¹² , or X ^{13 in} the above general formula (1A). A portion, or a portion of the cellulose skeleton that binds to an oxygen atom at the 2-position, 3-position, or 6-position, or a portion that binds to X ¹⁶ or X ^{17 in} the above general formula (1B), or a cellulose skeleton. Represents the part that bonds with the oxygen atom at the 3rd or 6th position of.)
<5> In the general formula (1C), X ¹⁸ is a single bond or −C (= O) −NH- (CH ₂ ) _2- O−, and p1 is 1. The liquid crystal material described.
<6> The liquid crystal material according to <4> or <5>, wherein the hydrophobic group is a linear or branched acyl group having 2 to 4 carbon atoms.
<7> The liquid crystal material according to <6>, wherein the acyl group is a linear or branched butyryl group.

<8> Has a three-dimensional structure
It contains a cellulose derivative having a molecular structure represented by the following general formula (2A) or the following general formula (2B).
The average number of hydroxyl groups per monomer unit is 0.3 or less.
A liquid crystal film in which the cellulose derivative contains a group having a linking group that links monomer units to each other.

(In the general formula ^{(2A), X 21, X} 22 and ^{X 23} each independently represent a single bond, an alkylene _{^{group, - (R 24 -O) j}} -, ^{or, -C (= O) -R 25} - R ²¹ , R ²² and R ²³ each independently represent a hydrogen atom, a group having the linking group or a hydrophobic group, and R ²⁴ and R ²⁵ each independently represent an alkylene group. , J represents an integer of 1 or more and 10 or less, and n21 represents an integer of 2 or more and 800 or less.)

(In the general formula ^{(2B), X 26} and ^{X 27} each independently represent a single bond, an alkylene _{^{group, - (R 28 -O) k}} -, ^{or, -C (= O) -R 29} - represents, R ²⁶ and R ²⁷ each independently represent a hydrogen atom, a group having the linking group, or a hydrophobic group, R ²⁸ and R ²⁹ each independently represent an alkylene group, and L ² is an alkyl. A group is represented, k represents an integer of 1 or more and 10 or less, and n22 represents an integer of 2 or more and 800 or less.)
<9> The liquid crystal film according to <8>, wherein the degree of substitution of the hydrophobic group per monomer unit is 1.0 or more and 2.9 or less.
<10> The liquid crystal film according to <8> or <9>, wherein the molecular structure represented by the general formula (2A) is a molecular structure represented by the following general formula (2A-1).

(In the general formula (2A-1), R ² represents -CH _2- CH _2- or -CH _2- CH (CH ₃ )-, and R ²¹ , R ²² and R ²³ are independent of each other. , Hydrogen atom, the group having the linking group, or the hydrophobic group, m2, t2 and r2 independently represent an integer of 0 or more and 10 or less, and n23 represents an integer of 2 or more and 800 or less. .)
<11> The group having the linking group is a group represented by the following general formula (2C).
The hydrophobic group is 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, and a carbon number of carbon atoms. A linear or branched acyl group of 2 to 18, a linear or branched alkoxy group having 1 to 18 carbon atoms, a carboxylic acid ester group represented by −COOR ^2A , or a halogen atom, wherein R ^2A is a carbon. Described in any one of <8> to <10>, which is a linear or branched alkyl group having the number 1 to 12, a cycloalkyl group having 3 to 12 carbon atoms, or an aryl group having 6 to 12 carbon atoms. Liquid crystal film.

(In the general formula (2C), R ^2C represents a hydrogen atom or a methyl group, and X ²⁸ is a single bond, a linear or branched alkylene group having 1 to 18 carbon atoms, or a cycloalkylene group having 3 to 18 carbon atoms. , An arylene group having 6 to 18 carbon atoms, or a linking group in which one or two or more selected from the group consisting of -O-, -NH-, -S-, and -C (= O)-is linked. Represented, p2 represents an integer of 1 or 2. However, the valence of X ²⁸ is p2 + 1. * Represents the bond position when the monomer units are linked. ** represents the above general formula. In (2A), the portion that binds to X ²¹ , X ²² , or X ²³ , or the portion that binds to an oxygen atom at the 2, 3, or 6 position of the cellulose skeleton is represented, or the above general formula (2B) ), Represents the portion that binds to X ²⁶ or X ²⁷ , or the portion that binds to the oxygen atom at the 3- or 6-position of the cellulose skeleton.)
<12> In the general formula (2C), X ²⁸ is a single bond or -C (= O) -NH- (CH ₂ ) _2- O-, and p2 is 1. The liquid crystal film described.
<13> The liquid crystal film according to <11> or <12>, wherein the hydrophobic group is a linear or branched acyl group having 2 to 4 carbon atoms.
<14> The liquid crystal film according to <13>, wherein the acyl group is a linear or branched butyryl group.

<15> The step of applying the liquid crystal material according to any one of <1> to <7> on the substrate, and
A step of applying heat or a step of irradiating ultraviolet rays to the liquid crystal material applied on the substrate,
A method for producing a liquid crystal film.
<16> A sensor including the liquid crystal film according to any one of <8> to <14>.
<17> The sensor according to <16>, which is a strain sensor that detects distortion of an object.
<18> The sensor according to <16>, which is a wearable sensor that detects biological information.
<19> An optical element including the liquid crystal film according to any one of <8> to <14>.

According to the present invention, a liquid crystal material containing a cellulose derivative, which exhibits thermotropic cholesteric liquid crystal properties, has elasticity, and can produce a liquid crystal film whose orientation is fixed at the wavelength of Bragg reflection. Is provided.
Further, according to the present invention, there is provided a liquid crystal film having elasticity and an orientation fixed at a wavelength of Bragg reflection, and a method for producing the liquid crystal film.
Further, according to the present invention, there is provided a sensor capable of detecting a mechanical stress corresponding to a wavelength (preferably a reflection color) according to the wavelength of reflection (preferably a reflection color).
Further, according to the present invention, there is provided an optical element capable of obtaining reflected light having a wavelength corresponding to the stress by applying a mechanical stress.

In this embodiment, it is the schematic which shows an example of the method of manufacturing the liquid crystal film whose orientation is fixed at the wavelength of different Bragg reflection. (A) is a liquid crystal cell after heating at the first temperature, and (B) is a liquid crystal cell after heating at the second temperature. 3 is an FT-IR spectrum of Example 3. It is a transmission spectrum in the process of raising temperature of the liquid crystal cell A provided with the liquid crystal material 1. It is a transmission spectrum in the process of raising temperature of the liquid crystal cell E provided with the liquid crystal material 3. It is a transmission spectrum of Example 4. It is a transmission spectrum of Example 5. It is a transmission spectrum of Example 6. It is a transmission spectrum of Example 8 before and after irradiation with ultraviolet rays. 6 is a graph showing the relationship between the number of cycles of applying and relaxing mechanical stress and the Bragg reflection wavelength in Example 7.

Hereinafter, the liquid crystal material according to the embodiment of the present invention will be described.
In the present specification, the numerical range represented by using "~" means a range including the numerical values before and after "~" as the lower limit value and the upper limit value.
Further, in the present specification, the (meth) acryloyl group means at least one of an acryloyl group and a methacryloyl group.

[Liquid crystal material]
The liquid crystal material of the present embodiment contains a cellulose derivative having a molecular structure represented by the following general formula (1A) or the following general formula (1B).
The cellulose derivative contains a hydrophobic group and a group having an unsaturated double bond, and the average number of hydroxyl groups per monomer unit is 0.3 or less, and the monomer of the group having an unsaturated double bond. The degree of substitution per unit (hereinafter, also referred to as “the degree of substitution of a group having an unsaturated double bond”) is 0.01 or more and 2.0 or less.
Here, the degree of substitution of the cellulose derivative means that at least a part of the hydroxyl groups or a part of the hydroxyl groups among the three hydroxyl groups of the cellulose monomer unit (D-glucopyranose (β-glucose)) is substituted with a substituent. It is an index showing the degree of being substituted, and specifically, it means the average number (≦ 3) substituted with the above-mentioned substituent.
The "degree of substitution group having an unsaturated double bond" in the present embodiment, in the case of having a molecular structure of cellulose derivative is represented by the general formula (1A) has the general formula (1A), R ^11, R ^12, and is introduced to the position of R ¹³ is the average number of "group having an unsaturated double bond". When the cellulose derivative has a molecular structure represented by the general formula (1B), the "group having an unsaturated double bond" introduced at the positions of R ¹⁴ and R ^{15 in} the general formula (1B) The average number.
Similarly, the degree of substitution of a hydrophobic group per monomer unit (hereinafter, also referred to as “degree of substitution of a hydrophobic group”) is generally used when the cellulose derivative has a molecular structure represented by the general formula (1A). In formula (1A), it is the average number of hydrophobic groups introduced at the positions of R ¹¹ , R ¹² , and R ¹³ . The cellulose derivative is in the case of having a molecular structure represented by the general formula (1B), to the general formula (1B), and the average number of hydrophobic groups introduced at the position of L ^1, R ¹⁴ and R ¹⁵ ..
In the present embodiment, in the case of a group having an unsaturated double bond and also corresponding to a hydrophobic group, such a group is regarded as a "group having an unsaturated double bond".
The cellulose derivative having a molecular structure represented by the general formula (1B) also corresponds to a chitosan derivative in which one amino group (-NH ₂ ) of a chitosan monomer unit is replaced by -NHCO-L ^1. ..

In the cellulose derivative of the present embodiment, the average number of hydroxyl groups per monomer unit is 0.3 or less, and the degree of substitution of the group having an unsaturated double bond is controlled to 0.01 or more and 2.0 or less.
That is, it can be said that the cellulose derivative in the present embodiment is a cellulose derivative that does not substantially contain a hydroxyl group and is introduced to such an extent that a group having an unsaturated double bond exhibits elasticity by cross-linking the cellulose derivative.
Here, the fact that the cellulose derivative does not substantially contain hydroxyl groups means that the average number of hydroxyl groups per monomer unit is 0.3 or less, preferably 0.2 or less, and more preferably 0.1. It means that it is as follows.
In the present embodiment, the purifying property of the cellulose derivative is improved because the cellulose derivative does not substantially contain a hydroxyl group. This improvement in purifying property is considered to contribute to the development of thermotropic cholesteric liquid crystallinity and the development of elasticity of the cellulose derivative after cross-linking. Further, by controlling the degree of substitution of the group having an unsaturated double bond within the above range, appropriate elasticity is imparted to the cellulose derivative after cross-linking.
Therefore, according to the liquid crystal material of the present embodiment, it is possible to produce a liquid crystal film having appropriate elasticity and having a fixed orientation at the wavelength of Bragg reflection by cross-linking between the monomers of the cellulose derivative.

<Cellulose derivative>
The cellulose derivative has a molecular structure represented by the general formula (1A) or the general formula (1B).

(Molecular structure represented by the general formula (1A))
The molecular structure represented by the general formula (1A) is shown below. In the molecular structure represented by the general formula (1A), [] represents a monomer unit. Hereinafter, [] is also simply referred to as a “monomer unit”. The same applies to general formulas other than the general formula (1A).

In the general formula ^{(1A), X 11, X} 12 and ^{X 13} each independently represent a single bond, an alkylene _{^{group, - (R 14 -O) h}} -, ^{or, -C (= O) -R 15} - the Represented, R ¹¹ , R ¹² and R ¹³ each independently represent a hydrogen atom, a group having an unsaturated double bond or a hydrophobic group, and R ¹⁴ and R ¹⁵ each independently represent an alkylene group. Represented, 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.

In the general formula (1A), the alkylene group represented by X ¹¹ , X ¹² and X ¹³ is not particularly limited, but is a linear or branched alkylene group having 1 to 18 carbon atoms (preferably 1 to 12), cyclic. Cycloalkylene group having 3 to 18 carbon atoms (preferably 3 to 12 carbon atoms) can be mentioned. Examples of the linear or branched alkylene group include a methylene group, an ethylene group, an n-propylene group, an isopropylene group, an n-butylene group, an isobutylene group, a sec-butylene group, a tert-butylene group and an n-pentylene group. Examples include an isopentylene group. Examples of the cyclic alkylene group include a cyclopentylene group and a cyclohexylene group.

In the general formula (1A), − (R ¹⁴ −O) _h − represented by X ¹¹ , X ¹² and X ¹³ is an alkyleneoxy group (alkylene ether group) or a polyalkyleneoxy group (polyalkylene ether group). is there. - ^(R 14 _{-O) h} - alkylene group in the group represented by ^{(-R 14} -) as is similar to the exemplified alkylene groups in the above ^(alkylene group represented by X ^{11, X 12} and ^{X 13)} Can be mentioned. -(R ^14- O) _h- includes, for example, an ethyleneoxy group, a polyethyleneoxy group, a propyleneoxy group, a polypropyleneoxy group and the like.
In the general formula (1A), h is preferably 1 or more and 6 or less, more preferably 1 or more and 4 or less, and further preferably 1 or more and 3 or less, from the viewpoint of obtaining a liquid crystal film having appropriate elasticity by crosslinking.

In the general formula ^(1A), -C represented by X ^{11, X 12} and ^{X 13 (= O) -R 15} - alkylene group in the group represented by ^{(-R 15} -) as is exemplified in the above Examples of the same group as the alkylene group (alkylene group represented by X ¹¹ , X ¹² and X ¹³ ) can be mentioned. -C (= O) ^{-R 15} - as, for _{example, -C (= O) -CH 2} -, - C (= O) -C 2 H 4 -, - C (= O) -C 3 H 6 -Etc.

Incidentally, an alkylene group as described _{^{above, - (R 14 -O) h}} -, ^{and, -C (= O) -R 15} - 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.

In the general formula (1A), the group having an unsaturated double bond represented by R ¹¹ , R ¹² and R ¹³ is not particularly limited, but for example, a group represented by the general formula (1C) described later, vinyl. Group, allyl group, vinyloxy group, isopropenyl group, 1-propenyl group, 2-butenyl group, 3-butenyl group, 1,3-butadienyl group, 2-pentenyl group, geranyl group, oleyl group, cycloalkenyl group (for example) , 2-Cyclopentene-1-yl group, 2-cyclohexene-1-yl group), vinylbenzyl group, cinnamyl group and the like.

In the general formula (1A), the hydrophobic group represented by R ¹¹ , R ¹² and R ¹³ is not particularly limited, but is a linear or branched alkyl group having 1 to 18 carbon atoms and a cyclo having 3 to 18 carbon atoms. Alkyl groups, aryl groups with 6 to 18 carbon atoms, aralkyl groups with 7 to 20 carbon atoms, linear or branched acyl groups with 2 to 18 carbon atoms, linear or branched alkoxy groups with 1 to 18 carbon atoms,- A carboxylic acid ester group represented by COOR ^1A or a halogen atom is preferable. Examples of the R ^1A 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, an acyl group having 2 to 18 carbon atoms (either linear or branched; the same applies hereinafter) having 2 to 18 carbon atoms is more preferable, and having 2 to 8 carbon atoms is more preferable from the viewpoint of easiness of synthesizing a cellulose derivative. An acyl group is more preferable, an acyl group having 2 to 4 carbon atoms is further preferable, and an acyl group having 4 carbon atoms (that is, a butyryl group) is particularly preferable.

The linear or branched alkyl group having 1 to 18 carbon atoms may be unsubstituted or substituted. 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, a tert-butyl group and the like. Examples of the substituent in the linear or branched alkyl group having 1 to 18 carbon atoms which 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, a methylcycloheptyl group and the like. .. Examples of the substituent in the cycloalkyl group having 3 to 18 carbon atoms which may be substituted include the same substituents as those exemplified above.

The aryl group having 6 to 18 carbon atoms may be unsubstituted or substituted. 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 aryl group having 6 to 18 carbon atoms which may be substituted include the same as the above-mentioned substituent.
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, a phenylethenyl group and the like. Examples of the substituent in the aralkyl group having 7 to 20 carbon atoms which may be substituted include the same substituents as those exemplified above.

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 which may be substituted include the same substituents as those exemplified above.

The linear or branched alkoxy group having 1 to 18 carbon atoms may be unsubstituted or substituted. 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 which may be substituted include the same substituents as those exemplified above.

The carboxylic acid ester group represented by −COOR ^1A may be unsubstituted or substituted. Specific examples of the unsubstituted carboxylic acid ester group include a linear or branched alkyl ester group having 2 to 12 carbon atoms (methyl ester group, ethyl ester group, etc.) and a cycloalkyl ester group having 4 to 12 carbon atoms. (Cyclopropyl ester group, cyclobutyl ester group, etc.), aryl ester group having 7 to 12 carbon atoms (phenyl ester group, etc.) can be mentioned.
The above-mentioned R ^{1A of a} optionally substituted carboxylic acid ester group (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). Examples of the substituent in the above include the same substituents as those exemplified above.
Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and the like.

In the general formula (1A), n11 is 2 or more and 800 or less, preferably 2 or more and 400 or less, and more preferably 2 or more and 300 or less, from the viewpoint of obtaining a liquid crystal film having appropriate elasticity by crosslinking.

In the general formula (1A), a preferred embodiment of the group having an unsaturated double bond represented by R ¹¹ , R ¹² and R ¹³ will be described later.

(Molecular structure represented by the general formula (1B))
The molecular structure represented by the general formula (1B) is shown below.

In the general formula ^{(1B), X 16} and ^{X 17} each independently represent a single bond, an alkylene ^{group, - (R 18 -O) i-} , ^{or, -C (= O) -R 19} - represents, R ¹⁶ and R ¹⁷ each independently represent a hydrogen atom, a group having an unsaturated double bond, or a hydrophobic group, R ¹⁸ and R ¹⁹ are independently alkylene groups, and L ¹ is It is an alkyl group, i represents an integer of 1 or more and 10 or less, and n12 represents an integer of 2 or more and 800 or less.

Examples of the alkylene group represented by X ¹⁶ and X ¹⁷ in the general formula (1B) include the same alkylene groups represented by X ¹¹ , X ¹² and X ¹³ in the general formula (1A) described above. ..
In the general formula (1B),-(R ^18- O) _i- represented by X ¹⁶ and X ¹⁷ is represented by X ¹¹ , X ¹² and X ¹³ in the above-mentioned general formula (1A)-( R ¹⁴ − O) The same as _h − can be mentioned. That is, R ¹⁸ is synonymous with R ¹⁴ , and i is synonymous with h.
In the general formula (1B), -C (= O) -R ¹⁹ -represented by X ¹⁶ and X ¹⁷ is represented by X ¹¹ , X ¹² and X ¹³ in the above general formula (1A). C (= O) ^{-R 15} - include the same one. That is, R ¹⁹ is synonymous with R ¹⁵ .

Incidentally, an alkylene group as described _{^{above, - (R 18 -O) i}} -, ^{and, -C (= O) -R 19} - may have a substituent. Examples of the substituent include the same substituents as those exemplified above.

In the general formula (1B), the group having an unsaturated double bond represented by R ¹⁶ and R ¹⁷ is an unsaturated double bond represented by R ¹¹ , R ¹² and R ¹³ in the above general formula (1A). Examples include those similar to groups with double bonds.
In the general formula (1B), the hydrophobic groups represented by R ¹⁶ and R ¹⁷ are the same as the hydrophobic groups represented by R ¹¹ , R ¹² and R ¹³ in the above general formula (1A). Can be mentioned.
That is, among the hydrophobic groups, an acyl group having 2 to 18 carbon atoms (either linear or branched. The same shall apply hereinafter) is more preferable, and 2 to 18 carbon atoms are more preferable, from the viewpoint of easiness of synthesizing the cellulose derivative. An acyl group of 8 is more preferable, an acyl group having 2 to 4 carbon atoms is further preferable, and an acyl group having 4 carbon atoms (that is, a butyryl group) is particularly preferable.

In the general formula (1B), the alkyl group represented by L ¹ is not particularly limited, but for example, as the hydrophobic group represented by R ¹¹ , R ¹² and R ¹³ in the above general formula (1A). Examples thereof include a linear or branched alkyl group having 1 to 18 carbon atoms and a cycloalkyl group having 3 to 18 carbon atoms. Of these, a linear or branched alkyl group having 1 to 6 carbon atoms is preferable.

In the general formula (1B), n12 is 2 or more and 800 or less, preferably 2 or more and 400 or less, and more preferably 2 or more and 300 or less, from the viewpoint of obtaining a liquid crystal film having appropriate elasticity.

(Molecular structure represented by the general formula (1A-1))
In the cellulose derivative of the present embodiment, the molecular structure represented by the general formula (1A) is preferably the molecular structure represented by the following general formula (1A-1).

In the general formula (1A-1), R ¹ represents -CH _2- CH _2- or -CH _2- CH (CH ₃ )-, and R ¹¹ , R ¹² and R ¹³ are independent of each other. It represents a hydrogen atom, a group having an unsaturated double bond, or a hydrophobic group, m1, t1 and r1 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. Represent.

In the general formula ^(1A-1), R ^{11, R 12} and ^{R 13} have the same meaning as ^{R 11, R 12} and ^{R 13} in the above general formula (1A).
In the general formula (1A-1), m1, t1 and r1 are independently, preferably 0 or more and 8 or less, more preferably 0 or more and 5 or less, and further preferably 0 or more and 5 or less, respectively, from the viewpoint of ease of synthesizing the cellulose derivative. Is preferably 0 or more and 3 or less.

In the general formula (1A-1), n13 has the same meaning as n11 in the above-mentioned general formula (1A), and the preferable range is also the same.
That is, in the general formula (1A-1), n13 is 2 or more and 800 or less, preferably 2 or more and 400 or less, and more preferably 2 or more and 300 or less from the viewpoint of obtaining a liquid crystal film having appropriate elasticity by crosslinking. Is.

In the general formula (1A-1), specifically, the molecular structure when R ¹ is represented by −CH ₂ −CH (CH ₃ ) − is represented by the following general formula (1a).

In the general formula (1a), R ¹¹ , R ¹² , R ¹³ and n ¹³ are synonymous with R ¹¹ , R ¹² , R ¹³ and n ¹³ in the general formula (1A-1). Further, m11, t11 and r11 are synonymous with m1, t1 and r1 in the general formula (1A-1).

In the general formula (1A-1), specifically, the molecular structure when R ¹ is represented by −CH ₂ −CH ₂ − is represented by the following general formula (1b).

In the general formula (1b), R ¹¹ , R ¹² , R ¹³ and n ¹³ are synonymous with R ¹¹ , R ¹² , R ¹³ and n ¹³ in the general formula (1A-1). Further, m12, t12, and r12 are synonymous with m1, t1, and r1 in the general formula (1A-1).

-Groups with unsaturated double bonds-
In the general formula (1A), a group having an unsaturated double bond represented by R ¹¹ , R ¹² and R ¹³ , or in the general formula (1B), an unsaturated double represented by R ¹⁶ and R ^17. As the group having a bond, a group represented by the following general formula (1C) is preferable from the viewpoint of obtaining a liquid crystal film having appropriate elasticity by crosslinking.

In the general formula (1C), R ^1C represents a hydrogen atom or a methyl group, and X ¹⁸ is a single bond or a linear or branched alkylene group having 1 to 18 carbon atoms, and a cycloalkylene having 3 to 18 carbon atoms. Represents a linking group in which one or more selected from the group consisting of a group, an arylene group having 6 to 18 carbon atoms, -O-, -NH-, -S-, and -C (= O)-is linked. , P1 represent an integer of 1 or 2. However, the valence of X ¹⁸ is p1 + 1.
** is in the general formula ^{(1A), X 11, X} 12, or a moiety that binds with ^{X 13, or,} X ^{11, X 12,} or if ^{X 13} is a single bond the 2-position of the cellulose backbone, 3 Represents the part that bonds with the oxygen atom at the 6th position. In addition, ** is the portion bonded to X ¹⁶ or X ¹⁷ in the above general formula (1B), or the oxygen atom at the 3rd or 6th position of the cellulose skeleton when X ¹⁶ or X ¹⁷ is a single bond. Represents the part to be combined.
In the general formula (1C), the linear or branched alkylene group having 1 to 18 carbon atoms represented by X ¹⁸ and the cycloalkylene group having 3 to 18 carbon atoms include X in the above general formula (1A). Examples thereof include those similar to the alkylene groups represented by ¹¹ , X ¹² and X ¹³ .
In the general formula (1C), the arylene group having 6 to 18 carbon atoms represented by X ¹⁸ is not particularly limited, and examples thereof include a phenylene group and a naphthalene group.
The above-mentioned 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 formula ^(1C), -O represented by ^{X 18 -, - NH -,} - S-, and -C (= O) - 1 one or two or more linking groups connecting selected from the group consisting of Although there is no particular limitation, for example, -C (= O) -NH- (CH ₂ ) ₂ -O-, -C (= O) -NH- (CH ₂ ) _2- O- (CH ₂ ) _2- Examples thereof include O-, -C (= O) -NH-C (CH ₃ )-(CH _2- O-) ₂ .
In the general formula (1C), as X ¹⁸ , a single bond or −C (= O) −NH− (CH ₂ ) ₂₋ O− is preferable.
In the group represented by the general formula (1C), the group in which R ^1C is a hydrogen atom or a methyl group, X ¹⁸ is a single bond, and p1 is 1, is a (meth) acryloyl group.

In the general formula (1C), p1 is preferably 1.
Preferred embodiments of the group represented by the general formula (1C) include groups represented by the formulas (1C-1) to (1C-6) described later. A specific example of the group represented by the general formula (1C) will be described later.

A preferred embodiment of the cellulose derivative having a molecular structure represented by the general formula (1A) is a cellulose derivative having a molecular structure represented by the general formula (1a) or a molecular structure represented by the general formula (1b). It is a cellulose derivative having. Specifically, in the general formula (1a), the hydrophobic group (R ¹¹ , R ¹² or R ¹³ ) is an acyl group having 2 to 4 carbon atoms (particularly preferably a butyryl group) and is an unsaturated double. The group having a bond (R ¹¹ , R ¹² or R ¹³ ) is a (meth) acryloyl group or -C (= O) -NH- (CH ₂ ) _2- OC (= O) -CH = CH. ₂ in which m11, t11 and r11 are independently integers of 0 or more and 3 or less and n13 is 2 or more and 300 or less; in the general formula (1b), the hydrophobic group (R ^11). , R ¹² or R ¹³ ) is an acyl group having 2 to 4 carbon atoms (particularly preferably a butyryl group), and a group having an unsaturated double bond (R ¹¹ , R ¹² or R ¹³ ) is (meth). ) Acryloyl group or -C (= O) -NH- (CH ₂ ) ₂ -OC (= O) -CH = CH ₂ , and m12, t12 and r12 are independently 0 or more. It is an integer of 3 or less, and n13 is 2 or more and 300 or less.

A preferred embodiment of the cellulose derivative having a molecular structure represented by the general formula (1B) is that the hydrophobic group (R ¹⁶ or R ¹⁷ ) is an acyl group having 2 to 4 carbon atoms in the general formula (1B). Particularly preferably, the butyryl group) and the group having an unsaturated double bond (R ¹⁶ or R ¹⁷ ) is a (meth) acryloyl group or -C (= O) -NH- (CH ₂ ) _2- OC (= O) -CH = CH ₂ , L ¹ is a linear or branched alkyl group with 1 to 6 carbon atoms (-NHCOL ¹ corresponds to a hydrophobic group), X ¹⁶ and In this embodiment, X ¹⁷ is a single bond and n12 is 2 or more and 300 or less.

An example of a group represented by the general formula (1C) (an example of a group having an unsaturated double bond) is shown below. The group represented by the general formula (1C) is not limited by these. In the following general formulas (1C-1) to (1C-6), ** represents a bonding position.

The group represented by the general formula (1C-5) is a group represented by the general formula (1C), and X ¹⁸ is a trivalent linking group represented by the following general formula (1C-7). , R ^1C is a hydrogen atom and p1 is 2. In the general formula (1C-7), *** represents a portion of the general formula (1C-5) that is bonded to a carbon atom bonded to CO (COCH = CH ₂ ).

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

-Average number of hydroxyl groups per monomer unit-
In the cellulose derivative of the present embodiment, the average number of hydroxyl groups per monomer unit is 0.3 or less from the viewpoint of improving the purification property of the cellulose derivative and from the viewpoint of obtaining a liquid crystal film having appropriate elasticity by crosslinking. Yes, preferably 0.2 or less, more preferably 0.1 or less.

-Degree of substitution of groups with unsaturated double bonds-
The degree of substitution of the unsaturated double bond group of the cellulose derivative is 0.01 or more and 2.0 or less, preferably 0.1, from the viewpoint of obtaining a liquid crystal film having appropriate elasticity by cross-linking the cellulose derivative. It is 1.5 or more, more preferably 0.2 or more and less than 1.0.

-Degree of substitution of groups with unsaturated double bonds / degree of substitution of hydrophobic groups-
In the cellulose derivative of the present embodiment, the ratio of the degree of substitution of the group having an unsaturated double bond to the degree of substitution of the hydrophobic group (group having an unsaturated double bond / hydrophobic group) is appropriate by cross-linking. From the viewpoint of obtaining an elastic liquid crystal film, it is preferably 3.0 × 10 ^-3 or more and 2.0 or less, more preferably 3.0 × 10 ^-2 or more and 1.0 or less, and further preferably 7.0 × 10 ^{−. It is 2} or more and 0.5 or less.

Substitution degree of and hydrophobic groups of a group having an unsaturated double bond, by H ¹ -NMR, is calculated from the integral value of characteristic proton peak with each substituent. Specifically, the solution obtained by dissolving a cellulose derivative in deuterochloroform in this embodiment, the H ¹ -NMR spectrum was measured under the following measurement conditions, based on the measured H ¹ -NMR spectrum will be described later in Example As shown in, a proton peak derived from a group having an unsaturated double bond; a proton peak derived from a hydrophobic group; a proton peak derived from a cellulose skeleton (for example, a proton peak in a β-glucose monomer unit); a cellulose skeleton. When is hydroxypropyl cellulose (HPC), it is calculated based on an integrated value such as the proton peak of the methine group of the hydroxypropyl group in the proton peak chain derived from HPC.
The average number of hydroxyl groups per monomer unit is calculated by subtracting the degree of substitution of a group having an unsaturated double bond and the degree of substitution of a hydrophobic group calculated by the above method from 3.
-Measurement conditions-
Equipment: Made by BRUKER: ULTRASHIELD400PLUS (model number)
Frequency: 400MHz

(Weight average molecular weight)
The weight average molecular weight of the cellulose derivative in the present embodiment is preferably 20,000 or more and 200,000 or less, more preferably 50,000 or more and 200,000 or less, and further preferably 100,000, from the viewpoint of obtaining a liquid crystal film having appropriate elasticity by crosslinking. More than 200,000 or less.
The weight average molecular weight of the cellulose derivative is calculated by gel permeation chromatography (GPC) (polystyrene standard). More specifically, it is calculated from the measurement results obtained under the following measurement conditions using a molecular weight calibration curve prepared from a polystyrene standard sample.
-Measurement conditions-
Equipment: Tosoh: HLC-8220GPC (model number)
Solvent: Tetrahydrofuran Column: 0021815 TSKgel SuperMultipore HZ-N (particle diameter 3 μm, inner diameter 4.6 mm × length 15 cm, manufactured by Tosoh Corporation)
Flow velocity: 0.15 mL / min Sample concentration: 2.0% by mass
Injection volume: 10 μL
Detector: Differential refractometer Temperature: 40 ° C

The molecular structure represented by the general formula (1A) and the specific example of the molecular structure represented by the general formula (1B) are shown below. The molecular structures represented by the general formula (1A) and the general formula (1B) are not limited thereto.

In the above formulas (1-1) to (1-8), in the general formula (1A-1), -R ^1- O- is -CH _2- CH (CH ₃ )-and m1 is 2. There is an example in which t1 is 2 and r1 is 0, but as a specific example other than the above example, a molecular structure in which m1, t1, and r1 are independently replaced with 0 or more and 10 or less is used. Can be mentioned.
Further, in the above formulas (1-9) to (1-13), in the general formula (1A-1), -R ^1- O- is -CH _2- CH _2- and m1 is 2. , T1 is 2 and r1 is 0. Specific examples other than the above example include a molecular structure in which m1, t1, and r1 are independently replaced with 0 or more and 10 or less. Be done.

<Cellulose derivative content>
In the liquid crystal material of the present embodiment, the ratio of the cellulose derivative to the whole liquid crystal material is preferably 80% by mass or more, more preferably 90% by mass or more, and further preferably 99% by mass or more. preferable.

<Other ingredients>
The liquid crystal material of the present embodiment may contain other components as long as the effects of the present embodiment are not exhibited. Other components include, for example, polymerization initiators, cross-linking agents, flame retardants, compatibilizers, antioxidants, mold release agents (release agents), light-resistant agents, weather-resistant agents, modifiers, antistatic agents, and hydrolysis. Inhibitors and the like can be mentioned.
As the polymerization initiator, a known polymerization initiator (for example, a thermal polymerization initiator or a photopolymerization initiator) can be used.

<Method for synthesizing cellulose derivatives>
The cellulose derivative in this embodiment is synthesized, for example, by the following method.
In the following, as an example of the cellulose derivative, a method for synthesizing a hydroxypropyl cellulose derivative having a molecular structure represented by the general formula (1A) will be described.
Hydroxypropyl cellulose (HPC) is dissolved in a solvent as a starting material to prepare an HPC solution.
The HPC solution is mixed with at least one of a compound having an unsaturated double bond (hereinafter, also referred to as “polymerizable compound”) and a compound having a hydrophobic group (hereinafter, also referred to as “hydrophobic compound”). To do.
Next, in this mixed solution, HPC is reacted with a polymerizable compound and a hydrophobic compound, and the hydrogen atoms of the three hydroxyl groups in the monomer unit of HPC are represented by a group having an unsaturated double bond or a hydrophobic group. Substitution (introduce a group having an unsaturated double bond or a hydrophobic group in the side chain (terminal) of HPC). It is preferable to mix the HPC solution with one of the polymerizable compound and the hydrophobic compound to introduce one into the side chain of HPC, and then mix the other to introduce the other into the side chain of HPC. As a result, an HPC derivative having a molecular structure represented by the general formula (1a) (an example of the general formula (1A)) can be obtained.

If hydroxyethyl cellulose is used as a starting material in the above synthesis, a cellulose derivative having a molecular structure represented by the general formula (1b) (an example of the general formula (1A)) can be obtained.
Further, a cellulose derivative having a molecular structure represented by the general formula (1A) can be obtained, for example, by the following method by a method according to the above method.
First, an alkylene group,-(R ^14- O) _h- (R ¹⁴ ; alkylene group,) is used between the oxygen atom and the hydrogen atom bonded to the 2-position, 3-position, and 6-position of the cellulose skeleton by a known method. h; 1 to 10 integer), ^{or, -C (= O) -R 15} - (R 15; prepare cellulose derivatives obtained by introducing a linking group having an alkylene group), which is the starting material. Next, the hydrogen atom at the end of this cellulose derivative (starting material) is replaced with a group having an unsaturated double bond or a hydrophobic group by a method according to the above method. As a result, a cellulose derivative having a molecular structure represented by the general formula (1A) can be obtained.
Further, a cellulose derivative having a molecular structure represented by the general formula (1B) can be obtained, for example, by the following method by a method according to the above method.
First, an alkylene group,-(R ^18- O) _i- (R ¹⁸ ; alkylene group, i; 1) is used between the oxygen atom and the hydrogen atom bonded to the 3- and 6-positions of the chitosan skeleton by a known method. to 10 integer), ^{or, -C (= O) -R 19} - (R 19; prepare cellulose derivatives obtained by introducing a linking group having an alkylene group) (chitosan derivative), which is the starting material. Next, the hydrogen atom at the end of this cellulose derivative is replaced with a group having an unsaturated double bond or a hydrophobic group by a method similar to the above method, and -NH ₂ at the 2-position of the chitosan skeleton is replaced with -NHCO. Substitute with −L ¹ (L ¹ ; alkyl group). As a result, a cellulose derivative having a molecular structure represented by the general formula (1B) can be obtained.

As the starting material (for example, HPC), a prepared substance or a commercially available substance may be used.
The solvent is not particularly limited as long as it can dissolve the starting material. Examples of the solvent include ketones such as acetone; alcohols such as methoxypropanol, ethoxyethanol and propanol; tetrahydrofuran; and the like.
As the compound having an unsaturated double bond (polymerizable compound), the group having the above-mentioned unsaturated double bond and having the unsaturated double bond is referred to in the above general formula (1A). It is not particularly limited as long as it can be introduced into R ¹¹ , R ¹² or R ¹³ , or R ¹⁶ or R ¹⁷ in the above general formula (1B), but among them, halogenated (meth) acryloyl (for example, chloride (meth)). Acryloyl, bromide (meth) acryloyl, etc.); Isocyanate (meth) acrylates (for example, Karens MOI (2-isocyanatoethyl methacrylate), Karens AOI (2-isocyanatoethyl acryloyl), Karens manufactured by Showa Denko Co., Ltd.) BEI (1,1-bisacryloyloxymethyl (ethylisocyanate)), Karenz MOI-EG, etc.); is preferable.
The compound having a hydrophobic group (hydrophobic compound) has the above-mentioned hydrophobic group, and the hydrophobic group is R ¹¹ , R ¹² or R ¹³ in the above general formula (1A), or the above general formula (1A). It is not particularly limited as long as it can be introduced into L ¹ , R ¹⁶ or R ¹⁷ in 1B), but among them, acyl halides (for example, acyl chloride (for example, acetyl chloride, propionyl chloride, butyryl chloride, pentanoyl chloride, etc.), etc.), Acyl bromide (acetyl bromide, propionyl bromide, butyryl bromide, pentanoyl bromide, etc.); is preferred.
An example of a specific method for synthesizing a cellulose derivative will be described in the section of Examples described later.

[Liquid crystal film]
The liquid crystal film of the present embodiment contains a cellulose derivative having a three-dimensional structure and a molecular structure represented by the general formula (2A) or the general formula (2B), and the average number of hydroxyl groups per monomer unit is 0. .3 or less, and the cellulose derivative contains a group having a linking group that links the monomer units to each other.
In the present embodiment, the cellulose derivative having a three-dimensional structure (that is, a crosslinked structure) crosslinks the monomer units of the cellulose derivative having a molecular structure represented by the above-mentioned general formula (1A) or general formula (1B). Obtained by As described above, the molecular structure represented by the general formula (1A) or the general formula (1B) is a cellulose derivative in which the average number of hydroxyl groups and the degree of substitution of a group having an unsaturated double bond are controlled within a specific range. is there.
Therefore, the cellulose derivative having a three-dimensional structure in the present embodiment is obtained by appropriately linking (crosslinking) the monomer units with each other by the linking group generated by the cleavage of the unsaturated double bond, that is, , It is obtained by cross-linking a polymer of a cellulose derivative, and does not substantially contain a hydroxyl group.
Here, the fact that the cellulose derivative does not substantially contain hydroxyl groups means that the average number of hydroxyl groups per monomer unit is 0.3 or less, preferably 0.2 or less, and more preferably 0.1. It means that it is as follows.
In the present embodiment, it is considered that the three-dimensional structure contributes to the development of elasticity of the liquid crystal film. Further, the cellulose derivative having a three-dimensional structure does not substantially contain a hydroxyl group, so that the purification property is improved. It is considered that this improvement in purifying property contributes to the development of cholesteric liquid crystal property and the development of elasticity of the liquid crystal film.
Therefore, according to the liquid crystal film of the present embodiment, it has elasticity and the orientation is fixed at the wavelength of Bragg reflection. Further, by applying a mechanical stress, reflected light having a wavelength corresponding to the stress can be obtained.

Here, the formation of the three-dimensional structure (crosslinked structure) can be confirmed by dissolving the liquid crystal film before and after the crosslinked in a solvent.
Specifically, since the liquid crystal film after cross-linking has a three-dimensional structure, it does not dissolve in a solvent (for example, acetone), but the liquid crystal film before cross-linking (that is, a liquid crystal material) without a three-dimensional structure is formed. Dissolves in solvent. By comparing the presence or absence of solubility in the solvent in this way, the formation of the three-dimensional structure can be confirmed.
Further, since the liquid crystal film of the present embodiment has a three-dimensional structure without using a cross-linking agent, it can be produced by a relatively simple method. The monomer units may be crosslinked with each other using a crosslinking agent.
Further, the liquid crystal film of the present embodiment has a structure in which the monomer units are crosslinked (three-dimensional structure), but this does not exclude the crosslinking in the monomer unit.

<Cellulose derivative>
The cellulose derivative in the present embodiment (hereinafter, also referred to as “cellulose derivative having a three-dimensional structure”) has a molecular structure represented by the general formula (2A) or the general formula (2B).

(Molecular structure represented by the general formula (2A))
The molecular structure represented by the general formula (2A) is shown below.

In the general formula ^{(2A), X 21, X} 22 and ^{X 23} each independently represent a single bond, an alkylene _{^{group, - (R 24 -O) j}} -, ^{or, -C (= O) -R 25} - the R ²¹ , R ²² and R ²³ each independently represent a hydrogen atom, a group having the linking group, or a hydrophobic group, and R ²⁴ and R ²⁵ each independently represent an alkylene group. j represents an integer of 1 or more and 10 or less, and n21 represents an integer of 2 or more and 800 or less.

In the general formula (2A), the alkylene groups represented by X ²¹ , X ²² and X ²³ are the same as the alkylene groups represented by X ¹¹ , X ¹² and X ¹³ in the above general formula (1A). Can be mentioned.

In the general formula (2A),-(R ^24- O) _j- and -C (= O) -R ²⁵ -represented by X ²¹ , X ²² and X ²³ are the above-mentioned general formula (1A). _{^{in) - (R 14 -O) h}} -, ^{and, -C (= O) -R 15} - include the same one. ^{Incidentally, - (R 24 -O) j} - is an alkylene group (alkylene ether group) or a polyalkyleneoxy group (polyalkylene ether group).

In the general formula (2A), the group represented by R ²¹ , R ²² and R ²³ and having a linking group for linking the monomer units (hereinafter, also simply referred to as “group having a linking group”) is not particularly limited. However, for example, a linking group formed by cleavage of a group having an unsaturated double bond represented by R ¹¹ , R ¹² and R ¹³ in the general formula (1A) can be mentioned.

In the general formula (2A), the hydrophobic groups represented by R ²¹ , R ²² and R ²³ are the same as the hydrophobic groups represented by R ¹¹ , R ¹² and R ¹³ in the general formula (1A) described above. Can be mentioned.
That is, among the hydrophobic groups, an acyl group having 2 to 18 carbon atoms (either linear or branched. The same shall apply hereinafter) is more preferable, and 2 to 18 carbon atoms are more preferable, from the viewpoint of easiness of synthesizing the cellulose derivative. An acyl group of 8 is more preferable, an acyl group having 2 to 4 carbon atoms is further preferable, and an acyl group having 4 carbon atoms (that is, a butyryl group) is particularly preferable.

In the general formula (2A), n21 is 2 or more and 800 or less, preferably 2 or more and 400 or less, and more preferably 2 or more and 300 or less from the viewpoint of having appropriate elasticity.

In the general formula (2A), a preferred embodiment of the group having a linking group represented by R ²¹ , R ²² and R ²³ will be described later.

(Molecular structure represented by the general formula (2B))
The molecular structure represented by the general formula (2B) is shown below.

In the general formula ^{(2B), X 26} and ^{X 27} each independently represent a single bond, an alkylene _{^{group, - (R 28 -O) k}} -, ^{or, -C (= O) -R 29} - represents, R ²⁶ and R ²⁷ each independently represent a hydrogen atom, a group having the linking group, or a hydrophobic group, R ²⁸ and R ²⁹ each independently represent an alkylene group, and L ² is an alkyl group. , K represents an integer of 1 or more and 10 or less, and n22 represents an integer of 2 or more and 800 or less.

In the general formula (2B), examples of the alkylene group represented by X ²⁶ and X ²⁷ include the same alkylene groups represented by X ¹¹ , X ¹² and X ¹³ in the general formula (1A) described above. ..

In the general formula ^(2B), represented by ^{X 26} and _{^{X 27 - (R 28 -O)}} k -, ^{and, -C (= O) -R 29} - as is in the above general formula (1A) - ^(R 14 _{-O) h} -, ^{and, -C (= O) -R 15} - include the same one.

In the general formula (2B), the group having a linking group represented by R ²⁶ and R ²⁷ is not particularly limited, but for example, the non-group represented by R ¹¹ , R ¹² and R ¹³ in the general formula (1A). Examples thereof include linking groups formed by cleavage of a group having a saturated double bond.

In the general formula (2B), the hydrophobic groups represented by R ²⁶ and R ²⁷ are the same as the hydrophobic groups represented by R ¹¹ , R ¹² and R ¹³ in the above general formula (1A). Can be mentioned.
That is, among the hydrophobic groups, an acyl group having 2 to 18 carbon atoms (either linear or branched. The same shall apply hereinafter) is more preferable, and 2 to 18 carbon atoms are more preferable, from the viewpoint of easiness of synthesizing the cellulose derivative. An acyl group of 8 is more preferable, an acyl group having 2 to 4 carbon atoms is further preferable, and an acyl group having 4 carbon atoms (that is, a butyryl group) is particularly preferable.

In the general formula (2B), the alkyl group represented by L ^2, the same one as the alkyl group represented by L ¹ in the above general formula (1A). That is, as the alkyl group represented by L ² , a linear or branched alkyl group having 1 to 6 carbon atoms is preferable.

In the general formula (2B), n22 is 2 or more and 800 or less, preferably 2 or more and 400 or less, and more preferably 2 or more and 300 or less from the viewpoint of having appropriate elasticity.

In the general formula (2B), a preferred embodiment of the group having a linking group represented by R ²⁶ and R ²⁷ will be described later.

(Group having a linking group for linking monomer units)
As the group having a linking group represented by the general formula (2A) or the general formula (2B), a group represented by the following general formula (2C) is preferable from the viewpoint of having appropriate elasticity.

In the general formula (2C), R ^2C represents a hydrogen atom or a methyl group, and X ²⁸ is a single bond or a linear or branched alkylene group having 1 to 18 carbon atoms, and a cycloalkylene having 3 to 18 carbon atoms. Represents a linking group in which one or more selected from the group consisting of a group, an arylene group having 6 to 18 carbon atoms, -O-, -NH-, -S-, and -C (= O)-is linked. , P2 represent an integer of 1 or 2.
* Represents the bond position when the monomer units are connected to each other. ** is in the general formula ^{(2A), X 21, X} 22, or a moiety that binds with ^{X 23, or,} X ^{21, X 22,} or if ^{X 23} is a single bond the 2-position of the cellulose backbone, 3 Represents the part that bonds with the oxygen atom at the 6th position. In addition, ** is the portion bonded to X ²⁶ or X ²⁷ in the above general formula (2B), or the oxygen atom at the 3rd or 6th position of the cellulose skeleton when X ²⁶ or X ²⁷ is a single bond. Represents the part to be combined.

In the general formula (2C), the linear or branched alkylene group having 1 to 18 carbon atoms represented by X ²⁸ and the cycloalkylene group having 3 to 18 carbon atoms include X in the above general formula (1A). Examples thereof include those similar to the alkylene groups represented by ¹¹ , X ¹² and X ¹³ .
In the general formula (2C), the arylene group having 6 to 18 carbon atoms represented by X ²⁸ is not particularly limited, and examples thereof include a phenylene group and a naphthalene group.
In the general formula (2C), one or two or more linking groups selected from the group consisting of -O-, -NH-, -S-, and -C (= O) -represented by X ²⁸ are linked. Although there is no particular limitation, for example, -C (= O) -NH- (CH ₂ ) ₂ -O-, -C (= O) -NH- (CH ₂ ) _2- O- (CH ₂ ) _2- Examples thereof include O-, -C (= O) -NH-C (CH ₃ )-(CH _2- O-) ₂ .
In the general formula (2C), as X ²⁸ , a single bond or -C (= O) -NH- (CH ₂ ) _2- O- is preferable.
In the group represented by the general formula (2C), the (meth) acryloyl group is cleaved in the group in which R ^2C is a hydrogen atom or a methyl group, X ¹⁸ is a single bond, and p2 is 1. It is a linking group that occurs in.

In the general formula (2C), p2 is preferably 1.
Preferred embodiments of the group represented by the general formula (2C) include general formulas (2C-1) to (2C-6), which will be described later, from the viewpoint of having appropriate elasticity. A specific example of the group represented by the general formula (2C) will be described later.

A preferred embodiment of the cellulose derivative having a molecular structure represented by the general formula (2A) or the general formula (2B) is that the hydrophobic group (R ²¹ , R ²² or R ²³ ) has the number of carbon atoms in the general formula (2A). A group of 2 to 4 acyl groups (particularly preferably a butyryl group) having a linking group (R ²¹ , R ²² or R ²³ ) represented by the general formula (2C) (preferably a general formula (preferably a general formula (2C)). In 2C), X ²⁸ is a single bond or a group having -C (= O) -NH- (CH ₂ ) _2- O-), and n21 is 2 or more and 300 or less; general. In formula (2B), the hydrophobic group (R ²⁶ or R ²⁷ ) is an acyl group having 2 to 4 carbon atoms (particularly preferably a butyryl group), and the group having a linking group (R ²⁶ or R ²⁷ ) is , A group represented by the general formula (2C) (preferably, in the general formula (2C), X ²⁸ is a single bond or a group having −C (= O) -NH- (CH ₂ ) ₂ −O−. ) comprising, ^{L 2} is an alkyl group having 1 to 3 carbon atoms, n23 is an embodiment is 2 to 300.

The following is an example of a group represented by the general formula (2C) (an example of a group having a linking group for linking monomer units). The group represented by the general formula (2C) is not limited by these. Note that * and ** represent the bonding position.

The linking group represented by the general formula (2C-5) is a linking group represented by the general formula (2C) in which X ²⁸ is a trivalent linking group represented by the following general formula (B5-1). It corresponds to a group in which R ^2C is a hydrogen atom and p2 is 2.

Among the groups having a linking group represented by the general formula (2C), from the viewpoint of having appropriate elasticity, the general formulas (2C-1), (2C-3), (2C-5) and (2C-6) ) Is preferable, and the groups represented by the general formula (2C-1) and the general formula (2C-3) are more preferable.

<Degree of substitution of hydrophobic groups>
In the liquid crystal film of the present embodiment, the degree of substitution of the hydrophobic group per monomer unit (degree of substitution of the hydrophobic group) is adjusted by adjusting the ratio of the group having the above-mentioned linking group in the cellulose derivative, and has appropriate elasticity to the liquid crystal film. From the viewpoint of imparting, it is preferably 1.0 or more and 2.9 or less, more preferably 2.0 or more and 2.9 or less, and further preferably 2.5 or more and 2.9 or less.
The degree of substitution of the hydrophobic group in the liquid crystal film of the present embodiment can be measured by the same method as the degree of substitution of the hydrophobic group in the liquid crystal material described above.

(Weight average molecular weight)
In the present embodiment, the weight average molecular weight of the cellulose derivative having a three-dimensional structure is not particularly limited.

The molecular structure represented by the general formula (2A) and the specific example of the molecular structure represented by the general formula (2B) are shown below. The molecular structure represented by the general formula (2A) or the general formula (2B) is not limited thereto. Note that * represents the bonding position.

In the above formulas (2-1) to (2-8), in the general formula (2A-1), -R ^2- O- is -CH _2- CH (CH ₃ )-and m2 is 2. This is an example in which t2 is 2 and r2 is 0, but as a specific example other than the above example, a molecular structure in which m2, t2, and r2 are independently replaced with 0 or more and 10 or less is used. Can be mentioned.
Further, in the above formulas (2-9) to (2-13), in the general formula (2A-1), -R ^2- O- is -CH _2- CH _2- and m2 is 2. , T2 is 2 and r2 is 0. Specific examples other than the above example include a molecular structure in which m2, t2, and r2 are independently replaced with 0 or more and 10 or less. Be done.

<Content of cellulose derivative with three-dimensional structure>
In the liquid crystal film of the present embodiment, the ratio of the cellulose derivative having a three-dimensional structure to the entire liquid crystal film is preferably 80% by mass or more, more preferably 90% by mass or more, and 99% by mass or more. It is more preferable to have.
<Other ingredients>
The liquid crystal film of the present embodiment may contain other components as long as the effects of the present embodiment are not exhibited. Other components include, for example, polymerization initiators, cross-linking agents, flame retardants, compatibilizers, antioxidants, mold release agents (release agents), light-resistant agents, weather-resistant agents, modifiers, antistatic agents, and hydrolysis. Inhibitors and the like can be mentioned. As the polymerization initiator, a known polymerization initiator (for example, a thermal polymerization initiator or a photopolymerization initiator) can be used.

<Manufacturing method of liquid crystal film>
The method for producing a liquid crystal film of the present embodiment includes a step of applying the liquid crystal material of the above embodiment on a substrate (hereinafter, also referred to as a “liquid crystal material applying step”) and heat applied to the liquid crystal material applied on the substrate. (Hereinafter, also referred to as “heat applying step”) or a step of irradiating ultraviolet rays (hereinafter, also referred to as “ultraviolet irradiation step”).
In the method for producing a liquid crystal film of the present embodiment, it is possible to obtain a liquid crystal film having elasticity and having Bragg reflection fixed at a specific wavelength by going through the above steps. Further, by applying a mechanical stress, it is possible to manufacture a liquid crystal film capable of obtaining reflected light having a wavelength corresponding to the stress.

(Liquid crystal material application process)
The liquid crystal material applying step is a step of applying the liquid crystal material of the above embodiment on the substrate.
The substrate is not particularly limited, and can be appropriately selected from commonly used substrates according to the purpose. Examples of the substrate include a glass substrate, a plastic substrate (for example, a polyethylene naphthalate (PEN) substrate, a polyethylene terephthalate (PET) substrate, a polycarbonate (PC) substrate, a polyimide (PI) substrate, etc.), an aluminum substrate, a stainless steel substrate, and the like. A semiconductor substrate such as a metal substrate or a silicon substrate can be used.
The thickness and shape of the substrate are not particularly limited, and it is preferable to appropriately select the substrate according to the purpose.
Examples of the method for applying the liquid crystal material onto the substrate include a coating method such as a spin coating method, a dip method, and a spray method; an inkjet method; a screen printing method; an injection method such as a vacuum injection method; and the like.
The form of the liquid crystal material may be solid (for example, powder) or liquid.
When the liquid crystal material is solid, it may be mixed with a solvent to make it liquid, and when the liquid crystal material has a liquid enough to be applied onto the substrate, it may be used as it is or it may be used as a solvent. You may use the mixture adjusted to the viscosity which is easy to use.
The liquid crystal material applied to the substrate may contain other components. Examples of other components include the same components as those described above (for example, polymerization initiators and release agents).
The solvent is not particularly limited, and for example, the solvent exemplified in the above-mentioned method for synthesizing a cellulose derivative can be used.

(Heat application process)
The heat applying step is a step of applying heat to the liquid crystal material applied on the substrate to cure the liquid crystal material. By the heat application step, the unsaturated double bond of the cellulose derivative before cross-linking is cleaved and the monomer units are linked (cross-linked) via the linking group, and as a result, elasticity is exhibited. In addition, the orientation is fixed at the wavelength of Bragg reflection.
The heat applying method is not particularly limited, and examples thereof include a method of applying heat using a known heating device (oven, infrared heater, hot plate).
The temperature at which heat is applied to the liquid crystal material is preferably 25 ° C. or higher and 130 ° C. or lower, more preferably 25 ° C. or higher and 120 ° C. from the viewpoint of having appropriate elasticity and fixing the orientation at the wavelength of Bragg reflection. ° C or lower, more preferably 25 ° C or higher and 110 ° C or lower. The temperature at which heat is applied to the liquid crystal material is controlled so that the liquid crystal material falls within the above range.
In the heat application step, by controlling the heat application conditions (temperature, heating time, etc.), the orientation can be easily fixed at the wavelength of Bragg reflection.

(Ultraviolet irradiation process)
The ultraviolet irradiation step is a step of irradiating the liquid crystal material applied on the substrate with ultraviolet rays to cure the liquid crystal material. By the ultraviolet irradiation step, the unsaturated double bond of the cellulose derivative before cross-linking is cleaved and the monomer units are linked (cross-linked) via the linking group, and as a result, elasticity is exhibited. In addition, the orientation is fixed at the wavelength of Bragg reflection.
The temperature at which the liquid crystal material is irradiated with ultraviolet rays (hereinafter, also referred to as “UV irradiation temperature”) is preferably 25 ° C. or higher and 130 ° C. or lower, more preferably 25 ° C. or higher and 120 ° C. or lower, and further preferably 25 ° C. or higher and 110 ° C. It is as follows. The temperature at which the liquid crystal material is irradiated with ultraviolet rays is controlled so that the liquid crystal material is within the above range.
Further, the ultraviolet irradiation intensity (UV illuminance) (hereinafter, also referred to as "UV irradiation intensity") is preferably 1 mW / cm ² or more and 20 mW / cm ² or less, more preferably 5 mW / cm ² or more and 20 mW / cm ² or less. More preferably, it is 10 mW / cm ² or more and 20 mW / cm ² or less.
In the ultraviolet irradiation step, by controlling the UV irradiation temperature and the UV irradiation intensity in combination, a liquid crystal film whose orientation is fixed by different Bragg reflections can be obtained.
More specifically, by controlling the UV irradiation temperature within the above range, the thermotropic cholesteric liquid crystal property of the cellulose derivative is exhibited, it becomes easy to adjust to a target color, and it becomes easy to obtain a desired color. Then, by controlling the UV irradiation temperature within the above range and further controlling the UV irradiation intensity within the above range, the color obtained by the UV irradiation temperature is fixed.
Therefore, in the ultraviolet irradiation step, by controlling both the UV irradiation temperature and the UV irradiation intensity (preferably the UV irradiation time), a multicolored liquid crystal film exhibiting the desired color at the target location can be obtained.
It should be noted that such a multicolored liquid crystal film (that is, a film in which the orientation is fixed by different Bragg reflections) can be easily obtained by using, for example, a photomask. Details will be described later.

(Alignment film forming process)
The method for producing a liquid crystal film of the present embodiment may include a step of forming an alignment film on a substrate (alignment film forming step).
That is, the alignment film forming step may be provided before the liquid crystal material applying step. By forming the alignment film, it is possible to easily fix the orientation at the wavelength of Bragg reflection in the heat application step or the ultraviolet irradiation step. It is preferable to apply a rubbing treatment to the alignment film.
Through the above steps, the liquid crystal film of the present embodiment is obtained.
The thickness of the liquid crystal film is not particularly limited, but is preferably 50 μm or more and 2000 μm or less, more preferably 100 μm or more and 1500 μm or less, and further preferably 200 μm or more and 1000 μm or less.
The liquid crystal film may be peeled off from the substrate or used as it is formed on the substrate.

Here, an example of a method for producing a liquid crystal film whose orientation is fixed at different Bragg reflection wavelengths will be described with reference to FIGS. 1 (A) and 1 (B). Here, a method of manufacturing a liquid crystal film using a photomask processed into a T shape (using a negative photoresist) will be described.
As shown in FIG. 1A, an alignment film (not shown) is formed on the first substrate 12, and the alignment film is subjected to a rubbing treatment. In the same manner, an alignment film (not shown) is formed on the second substrate 14, and the alignment film is subjected to a rubbing treatment as needed. Next, the liquid crystal material 18 is injected between the first substrate 12 and the second substrate 14 on which the alignment film is formed via a spacer (not shown). As a result, the liquid crystal cell 10 is obtained. The liquid crystal cell 10 is composed of a first substrate 12 with an alignment film, a second substrate 14 with an alignment film, and a liquid crystal material 18 provided between these substrates via a spacer (not shown).
Next, the photomask 16 cut out in a T shape is placed above the liquid crystal cell 10, and the temperature of the liquid crystal cell 10 (liquid crystal material) is first from the side of the first substrate 12 on which the alignment film is formed. The liquid crystal cell 10 is heated so as to have a temperature of (X ° C .: for example, 105 ° C. in FIG. 1 (A)). After that, the liquid crystal cell 10 is irradiated with ultraviolet rays at a predetermined irradiation intensity for a predetermined time by passing ultraviolet rays through the opening (T-shape) of the photomask 16 (first UV irradiation). As a result, the orientation of the portion of the liquid crystal material subjected to the first UV irradiation at the first temperature is fixed by the first Bragg reflection.
Next, the photomask 16 is removed, and the liquid crystal cell 10 is cooled to a second temperature (Y ° C .: for example 95 ° C. in FIG. 1 (B)) lower than the first temperature (X ° C.) to obtain a second temperature. Maintain the temperature of. Then, while maintaining the second temperature, the entire liquid crystal cell 10 is irradiated with ultraviolet rays at a predetermined irradiation intensity for a predetermined time (second UV irradiation). As a result, the orientation of the portion of the liquid crystal material that has undergone the second UV irradiation at the second temperature is fixed by the second Bragg reflection.
Through the above steps, a liquid crystal film 20 whose orientation is fixed by different Bragg reflections and a liquid crystal cell 10A including the liquid crystal film 20 can be obtained. The liquid crystal cell 10A is composed of a first substrate 12 with an alignment film, a second substrate 14 with an alignment film, and the liquid crystal film 20 provided between these substrates via a spacer (not shown). ..
The temperature of the liquid crystal cell (liquid crystal material) when irradiating with ultraviolet rays is higher than the first temperature (X ° C. in FIG. 1 (A)) and the second temperature (Y ° C. in FIG. 1 (B)). It is also preferable to increase the temperature. This makes it easier to fix the orientation with different Bragg reflections. The first temperature may be lower than the second temperature (X ° C <Y ° C). Further, the alignment film does not have to be formed.

<Use of liquid crystal film>
The liquid crystal film of the present embodiment is, for example, an optical film such as a polarizing film, a retardation film, a backlight, an antireflection film, a light diffusion film, a brightness improving film, and an antiglare film; distortion, expansion / contraction, vibration, impact, etc. of an object. Sensors (pressure sensor, strain sensor, expansion / contraction sensor, vibration sensor, impact sensor, etc.) that detect deformation caused by reflection by the wavelength of reflection (preferably reflection color); biological information such as pulse wave, respiration, and heartbeat. , A wearable sensor that detects by the wavelength of reflection (preferably a reflected color); an optical element using the above optical film; an optical element other than the above; a liquid crystal display element; and the like.
The liquid crystal film of the present embodiment has elasticity, and by applying a mechanical stress, reflected light having a wavelength corresponding to the applied stress can be obtained. Therefore, the mechanical stress is determined by the reflection wavelength (preferably the reflected color). It is preferable to mount it on a sensor that can detect it or an optical element that can obtain reflected light by applying mechanical stress.

〔sensor〕
The sensor of this embodiment includes the liquid crystal film of the above embodiment.
Examples of the sensor include various sensors exemplified above.

<Strain sensor>
The sensor of this embodiment is preferably a strain sensor that detects the strain of an object.
Since the distortion sensor of the present embodiment includes the liquid crystal film of the above embodiment, it is possible to detect the deformation caused by the distortion of the object by the wavelength of reflection (preferably the reflected color).
For example, by installing the strain sensor of the present embodiment in advance at a location of an object (for example, a structure such as a bridge or a building) where distortion is likely to occur, the degree of distortion of the object can be detected. Further, the mechanical stress caused by the distortion (deformation) can be detected visually, that is, by the wavelength of reflection (preferably the reflection color).

<Wearable sensor>
The sensor of this embodiment is preferably a wearable sensor that detects biological information. A wearable sensor is a relatively small sensor that can be worn and used.
Since the wearable sensor of the present embodiment includes the liquid crystal film of the above embodiment, biological information can be detected by the wavelength of reflection (preferably the reflected color).
For example, the strain sensor of this embodiment is directly attached or attached to a place where biological information is to be acquired (for example, on the skin), or clothing, underwear, socks, gloves, a tie, a handkerchief, a muffler, a watch, glasses, shoes, etc. By attaching or wearing it on slippers, hats, etc., biological information (pulse waves, breathing, heartbeat, body movements (muscle movements, etc.), etc.) can be visualized, that is, the wavelength of reflection (preferably reflected color). Can be obtained by.

[Optical element]
The optical element of this embodiment includes the liquid crystal film of the above embodiment.
By artificially applying a mechanical stress to the optical element of the present embodiment or pre-installing the optical element in a place where the mechanical stress is naturally applied, different reflected light corresponding to the stress can be obtained. Applications of such optical elements include toys, emergency light sources, interiors (figures, shelves, etc.), building materials (floors, walls, stairs, etc.), tableware, containers, and the like.

The present invention will be described below with reference to Examples, but the present invention is not limited to these Examples. In the following description, all "%" are based on mass unless otherwise specified. “Wt%” means mass%.

[Example 1]
<Preparation of liquid crystal material 1>
Hydroxypropyl cellulose derivative 1 (hereinafter, also referred to as “HPC derivative 1”) was synthesized as a cellulose derivative according to the following scheme A.
Hydroxypropiocellulose (HPC) was dried under reduced pressure at room temperature (25 ° C.) for 12 hours or longer. 3.0 g of HPC was weighed in a nitrogen-filled three-necked flask and dissolved in 10 mL of dehydrated acetone with stirring to obtain an HPC solution. At this time, the number of moles of hydroxy groups in the β-glucose monomer unit (monomer unit) was calculated to be 15 mmol from the MS value (average number of hydroxypropyl groups per monomer unit). The HPC solution was shielded from light with aluminum foil, and 1.0 mL (12 mmol) of acryloyl chloride was added at room temperature. After reacting at room temperature in the dark for 24 hours, 7.9 mL (76 mmol) of butyryl chloride was added, and the reaction was further carried out for 24 hours. After completion of the reaction, the reaction solution was poured into 500 mL of ultrapure water while maintaining the light-shielded state to obtain a black glutinous product. The product was washed with ultrapure water and dried. Subsequently, the product was dissolved in a small amount of acetone and then reprecipitated in 500 mL of ultrapure water. This redissolution and reprecipitation operation was performed three times to obtain a white rice cake-like product. After washing the product with ultrapure water and drying it in a cool and dark place for 2 days, the HPC side chain (hydrogen atom of the hydroxyl group of HPC) was replaced with an acryloyl group or a butyryl group as the HPC derivative 1. "Acryloyl / butyryl mixed ester" (hereinafter, also referred to as HPC-Ac / BuE (1)) was obtained. This was designated as the liquid crystal material 1. The yield was 2.5 g.
Further, by the method described above, HPC-Ac / BuE (1 ) Results of measurement of the weight average molecular weight of, the weight average molecular weight was 1.5 × 10 ^5.
In HPC-Ac / BuE (1), in the general formula (1A), X ¹¹ is (-CH _2- CH (CH ₃ ) -O-) ₂ , R ¹¹ is an acryloyl group, and X ¹² Is (-CH _2- CH (CH ₃ ) -O-) ₂ , R ¹² is a butyryl group, X ¹³ is a single bond, R ¹³ is a butyryl group, and n11 is 250. It is an HPC derivative having.

( ¹ Measurement of ¹ H-NMR spectrum)
The ¹ H-NMR spectrum of HPC-Ac / BuE (1) (liquid crystal material 1) was measured. The results are shown below.
First, the peak of the proton of deuterated chloroform is at 7.2 ppm as a peak not derived from HPC-Ac / BuE (1). As peaks derived from HPC-Ac / BuE (1), peaks (a, b, c) near 5.8 ppm, 6.1 ppm, and 6.4 ppm are peaks of protons attached to the double bond of the acryloyl group, respectively. The peak (e) near 4.7 ppm to 5.2 ppm is the peak of the proton derived from the methylene group of the methine group of the terminal hydroxypropyl group. The peaks around 2.7 ppm to 4.5 ppm are the peaks of the protons in the β-glucose monomer unit and the protons of the methine group of the hydroxypropyl group in the chain (proton peaks derived from the HPC skeleton, indicated as "HPC" in the spectrum. ). The peak near 2.3 ppm is the peak of the proton of the methylene group (f) of the butyryl group adjacent to the carboxyl group. The peak near 1.6 ppm is the peak of the proton of the methylene group (g) adjacent to the end of the butyryl group. The peak around 0.9 ppm to 1.0 ppm is the peak of the proton of the methyl group (h) at the end of the butyryl group, and the peak around 1.0 ppm to 1.3 ppm is the peak of the methyl group (d) at the end of the hydroxypropyl group. It is the peak of the proton of.
Based on the assigned peak, the degree of substitution of the acryloyl group (hereinafter, also referred to as "acryloylation degree") and the degree of substitution of the butyryl group (hereinafter, "butyryl ester") in the HPC side chain (hydrogen atom of the hydroxyl group of HPC) (Also called "degree of conversion") was calculated. As a result, the degree of substitution of the acryloyl group was 0.77, and the degree of substitution of the butyryl group was 2.06.

[Example 2]
<Preparation of liquid crystal material 2>
HPC derivative 2 was synthesized as a cellulose derivative according to the above scheme A.
HPC-similar to HPC-Ac / BuE (1), except that the amount of acryloyl chloride added was changed to 5.0 mL (62 mmol) and the amount of butyryl chloride added was changed to 4.3 mL (41 mmol). Ac / BuE (2) (HPC derivative 2) was obtained. This was designated as the liquid crystal material 2. The yield was 2.5 g.
Further, by the method described above, HPC-Ac / BuE (2 ) Results of measurement of the weight average molecular weight of, the weight average molecular weight was 1.5 × 10 ^5.
In HPC-Ac / BuE (1), in the general formula (1A), X ¹¹ is (-CH _2- CH (CH ₃ ) -O-) ₂ , R ¹¹ is an acryloyl group, and X ¹² Is (-CH _2- CH (CH ₃ ) -O-) ₂ , R ¹² is a butyryl group, X ¹³ is a single bond, R ¹³ is a butyryl group, and n11 is 70. It is an HPC derivative having.

( ¹ Measurement of ¹ H-NMR spectrum)
^{1 1} H-NMR spectrum was measured by the method described above.
A peak derived from HPC-Ac / BuE (2) was confirmed at a position substantially similar to the peak of HPC-Ac / BuE (1).
Based on the assigned peak, the degree of substitution of the acryloyl group (degree of acryloylation) and the degree of substitution of the butyryl group (degree of butyryl esterification) in the HPC side chain (hydrogen atom of the hydroxyl group of HPC) were calculated. As a result, the degree of substitution of the acryloyl group was 1.98, and the degree of substitution of the butyryl group was 0.66.

[Example 3]
<Preparation of liquid crystal material 3>
HPC derivative 3 was synthesized as a cellulose derivative according to the following scheme B.
Hydroxypropiocellulose (HPC) was dried under reduced pressure at room temperature (25 ° C.) for 12 hours or longer. 2.0 g of HPC was weighed in a nitrogen-filled three-necked flask and dissolved in 10 mL of dehydrated acetone with stirring to obtain an HPC solution. At this time, the number of moles of hydroxy groups in the β-glucose monomer unit (structural unit) was calculated to be 15 mmol from the MS value (average number of hydroxypropyl groups per monomer unit). The HPC solution was shielded from light with aluminum foil, and 0.3 mL (2.4 mmol) of 2-isocyanatoethyl acrylate (manufactured by Showa Denko: Karenz AOI) was added at room temperature. After reacting at room temperature in the dark for 24 hours, 5.7 mL (55 mmol) of butyryl chloride was added, and the reaction was further carried out for 24 hours. After completion of the reaction, the reaction solution was poured into 500 mL of ultrapure water while maintaining the light-shielded state to obtain a black glutinous product. The product was washed with ultrapure water and dried. Subsequently, the product was dissolved in a small amount of acetone and then reprecipitated in 500 mL of ultrapure water. This redissolution and reprecipitation operation was performed three times to obtain a white rice cake-like product. After washing the product with ultrapure water and drying it in a cool and dark place for 2 days, the HPC side chain (hydrogen atom of the hydroxyl group of HPC) becomes CH ₂ = CH-C (= O)-as the HPC derivative 3. O- (CH ₂ ) _2- NHC (= O)-and "HPC acryloyl carbamate / butyryl mixed ester" substituted with a butyryl group (hereinafter, also referred to as HPC-Ac · Ca / BuE) were obtained. This was designated as the liquid crystal material 3. The yield was 1.8 g.
In HPC-Ac · Ca / BuE, in the general formula (1A), X ¹¹ is (-CH _2- CH (CH ₃ ) -O-) ₂ and R ¹¹ is RNHCO- (R is CH _2). = CH-C (= O) -O- (CH ₂ ) _2- ), X ¹² is (-CH _2- CH (CH ₃ ) -O-) ₂ , and R ¹² is a butyryl group. An HPC derivative having a molecular structure in which X ¹³ is a single bond, R ¹³ is a butyryl group, and n 11 is 285.

( ¹ Measurement of ¹ H-NMR spectrum)
The ¹ H-NMR spectrum of HPC-Ac · Ca / BuE was measured. The results are shown below.
First, the peak of the proton of deuterated chloroform is at 7.2 ppm as a peak not derived from HPC-Ac · Ca / BuE. As peaks derived from HPC-Ac / Ca / BuE, peaks (a, b, c) near 5.8 ppm, 6.1 ppm, and 6.4 ppm are peaks of protons attached to the double bond of the acryloyl group, respectively, and 4 The peaks (e, j) around 7.7 ppm to 5.2 ppm are the peaks of the methine group of the terminal hydroxypropyl group and the protons derived from the methylene group adjacent to the carbamate of 2-isocyanatoethyl acrylate. The peak around 2.7 ppm to 4.5 ppm is derived from the proton in the β-glucose monomer unit, the proton of the methine group of the hydroxypropyl group in the chain, and the methylene group adjacent to the acrylate group of 2-isocyanatoethyl acrylate. It is a proton peak (i, a proton peak derived from the HPC skeleton (indicated as “HPC” in the spectrum)). The peak near 2.3 ppm is the peak of the proton of the methylene group (f) of the butyryl group adjacent to the carboxyl group. The peak near 1.6 ppm is the peak of the proton of the methylene group (g) adjacent to the end of the butyryl group. The peak around 0.9 ppm to 1.0 ppm is the peak of the proton of the methyl group (h) at the end of the butyryl group, and the peak around 1.0 ppm to 1.3 ppm is the peak of the methyl group (d) at the end of the hydroxypropyl group. It is the peak of the proton of.
More specifically, for the peak of 4.7 ppm to 5.2 ppm, the peak of the proton of the methine group when the terminal hydroxypropyl group is carbamate (or esterified) and the 2-position or 3 of the β-glucose monomer unit. There is a possibility of a peak of the proton of the methine group when the position is carbamate (or esterified).
Degree of substitution of CH ₂ = CH-C (= O) -O- (CH ₂ ) _2- NHC (= O)-in the HPC side chain (hydrogen atom of the hydroxyl group of HPC) based on the assigned peak. (Hereinafter, also referred to as "acryloyl carbamate degree") and the degree of substitution of the butyryl group (hereinafter, also referred to as "butyryl esterification degree") were calculated. As a result, the degree of substitution of CH ₂ = CH-C (= O) -O- (CH ₂ ) _2- NHC (= O)-was 0.05, and the degree of substitution of the butyryl group was 2.9. ..

Liquid crystal films 1 to 6 were produced using the liquid crystal materials 1 to 3.

[Example 4]
<Preparation of liquid crystal film 1>
A liquid crystal alignment film as 2.0 wt% of polyvinyl alcohol (PVA) (Aldrich ^{_{Corp., M W: 1.3 × 10 4}} ~2.3 × 10 4, the degree of hydrolysis (hydrolyzed): 87% ~89% ) aqueous solution Was prepared. Using a spin coater (manufactured by Active: ACT-220D II), a 2.0 wt% PVA aqueous solution was spin-applied to a commercially available slide glass (base) at 800 rpm for 10 seconds, and subsequently at 2000 rpm for 20 seconds to apply the PVA-coated substrate. Obtained. Then, the PVA-coated substrate was rubbed 50 times in the uniaxial direction using a rod wound with cupra to perform a rubbing treatment. Further, in preparation for the peeling operation, the release agent was spin-applied at 200 rpm for 10 seconds, followed by 500 rpm for 10 seconds. As a result, a PVA glass substrate that had been subjected to a rubbing treatment and a peeling treatment (hereinafter, also referred to as “rubbing / peeling treated PVA glass substrate”) was obtained. A total of two PVA glass substrates with rubbing / peeling treatment were produced.
HPC-Ac / BuE (1) (liquid crystal material 1) is sandwiched between two rubbing / peeling-treated PVA glass substrates with a 200 μm polytetrafluoroethylene (PTFE) spacer on a hot stage heated to 90 ° C. It is. Further, by performing a shear alignment treatment, a liquid crystal cell A having a uniformly oriented liquid crystal material 1 (thickness 200 μm) was obtained.

Next, the liquid crystal film 1 was produced according to the method shown in FIG.
First, a photomask (negative pattern) cut out in a T shape was covered above the liquid crystal cell A. Next, the liquid crystal cell A (liquid crystal material 1) is heated to 60 ° C. (first temperature: in FIG. 1 (A)) so that the first portion (the portion corresponding to the T-shape) of the liquid crystal material 1 exhibits a red color. , X ° C.), and then ultraviolet rays around 365 nm (irradiation intensity: 13 mW / cm ² ) are used as a light source, and the opening of the photo mask is passed through an optical filter (UV-35 / UV-D36A) using a mercury xenon lamp as a light source. The liquid crystal cell A was irradiated for 40 minutes through the portion (T-shaped).
Next, the photomask is removed, and then the liquid crystal cell A (liquid crystal material 1) is heated to 40 ° C. (second temperature) so that the second portion (the portion other than the first portion) of the liquid crystal material 1 exhibits green color. : Cooled to Y ° C. in FIG. 1 (B), and while maintaining the second temperature (40 ° C.), the above ultraviolet rays (irradiation intensity: 13 mW / cm ² ) were applied to the entire liquid crystal cell A for 40 minutes. Irradiated.
Through the above steps, a liquid crystal cell A provided with the liquid crystal film 1 (cured film of the liquid crystal material 1) and the liquid crystal film 1 was produced.
Then, the tweezers were inserted into the gap of the liquid crystal cell A and slowly pulled up to peel the liquid crystal film 1 from the liquid crystal cell A. As a result, the liquid crystal film 1 was obtained.
The obtained liquid crystal film 1 was red and green, and had elasticity. Further, when the liquid crystal film 1 was pressed with a finger, the color changed. Therefore, in Example 4, it was found that the liquid crystal film 1 is obtained in which the orientation is fixed at different Bragg reflection wavelengths and the reflected light corresponding to the stress is obtained by applying the mechanical stress.
In the production of the liquid crystal film 1, the liquid crystal cell A is the liquid crystal cell 10 (after heating at the first temperature) in FIG. 1 (A) and the liquid crystal cell 10A (second temperature) in FIG. 1 (B). The two rubbing / peeling-treated PVA glass substrates correspond to the first substrate 12 and the second substrate 14 in FIGS. 1 (A) and 1 (B), and have a T-shape. The cut-out photomask corresponds to the photomask 16 in FIG. 1 (A), and the liquid crystal film 1 corresponds to the liquid crystal film 20 in FIG. 1 (B).

[Example 5]
<Preparation of liquid crystal film 2>
The photomask cut out in a T shape is changed to a photomask cut out in a U shape (negative pattern) so that the first part (the part corresponding to the U shape) of the liquid crystal material 1 exhibits green color. Except that the first temperature was set to 95 ° C. and the second temperature was changed to 75 ° C. so that the second part (parts other than the first part) of the liquid crystal material 1 was blue. A liquid crystal cell B including a liquid crystal film 2 and a liquid crystal film 2 was obtained in the same manner as in Example 4.
The obtained liquid crystal film 2 had green and blue colors and had elasticity. Further, when the liquid crystal film 2 was pressed with a finger, the color changed. Therefore, in Example 5, it was found that the liquid crystal film 2 can be produced in which the orientation is fixed at different Bragg reflection wavelengths and the reflected light having a wavelength corresponding to the stress can be obtained by applying a mechanical stress.

[Example 6]
<Preparation of liquid crystal film 3>
The photomask cut out in a T-shape is changed to an S-shaped photomask (positive pattern) so that the first part of the liquid crystal material 1 (the part other than the part corresponding to the S-shape) is red. Except for changing the second temperature to 80 ° C. so that the first temperature is 105 ° C. and the second portion (the portion corresponding to the S-shape) of the liquid crystal material 1 is blue. A liquid crystal cell C including a liquid crystal film 3 and a liquid crystal film 3 was obtained in the same manner as in Example 4.
The obtained liquid crystal film 3 had red and blue colors and had elasticity. Further, when the liquid crystal film 3 was pressed with a finger, the color changed. Therefore, in Example 6, it was found that the liquid crystal film 3 can be produced in which the orientation is fixed at different Bragg reflection wavelengths and the reflected light having a wavelength corresponding to the stress can be obtained by applying a mechanical stress.

[Example 7]
<Preparation of liquid crystal film 4>
Except for changing the liquid crystal material 1 to the liquid crystal material 2 and heating the entire liquid crystal cell B at 30 ° C. and irradiating with ultraviolet rays for 10 minutes so that the cured liquid crystal material 2 exhibits a red color without using a photo mask. Obtained a liquid crystal cell 4 and a liquid crystal cell D provided with the liquid crystal film 4 in the same manner as in Example 4.
The obtained liquid crystal film 4 had a red color and had elasticity. Further, when the liquid crystal film 4 was pressed with a finger, the color changed. Therefore, in Example 7, it was found that the liquid crystal film 4 can be produced in which the orientation is fixed at the wavelength of Bragg reflection and the reflected light having a wavelength corresponding to the stress can be obtained by applying a mechanical stress.

[Example 8]
<Preparation of liquid crystal film 5>
A liquid crystal alignment film as 2.0 wt% of polyvinyl alcohol (PVA) (Aldrich ^{_{Corp., M W: 1.3 × 10 4}} ~2.3 × 10 4, the degree of hydrolysis (hydrolyzed): 87% ~89% ) aqueous solution Was prepared. Using a spin coater (manufactured by Active: ACT-220D II), a 2.0 wt% PVA aqueous solution was spin-applied to a commercially available slide glass (base) at 800 rpm for 10 seconds, and subsequently at 2000 rpm for 20 seconds to apply the PVA-coated substrate. Obtained. Then, the PVA-coated substrate was rubbed 50 times in the uniaxial direction using a rod wound with cupra to perform a rubbing treatment. Further, in preparation for the peeling operation, the release agent was spin-applied at 200 rpm for 10 seconds, followed by 500 rpm for 10 seconds. As a result, a rubbing / peeling-treated PVA glass substrate was obtained. A total of two PVA glass substrates with rubbing / peeling treatment were produced.
HPC-Ac · Ca / BuE (liquid crystal material 3) was sandwiched between two rubbing / peeling treated PVA glass substrates with a 200 μm polytetrafluoroethylene (PTFE) spacer on a hot stage heated to 90 ° C. .. Further, by performing a shear alignment treatment, a liquid crystal cell E having a uniformly oriented liquid crystal material 3 (thickness 200 μm) was obtained.

Next, the liquid crystal cell E (liquid crystal material 3) was heated at 100 ° C. Then, using a mercury xenon lamp as a light source, the liquid crystal cell E was irradiated with ultraviolet rays (UV) of about 15 mW / cm ² at around 365 nm through an optical filter (UV-35 / UV-D36A) for 40 minutes.
Then, while maintaining the liquid crystal cell E at 100 ° C., the liquid crystal cell E was irradiated with ultraviolet rays of 15 mW / cm ² at 365 nm for 10 minutes. As a result, a liquid crystal cell E provided with the liquid crystal film 5 (cured film of the liquid crystal material 3) and the liquid crystal film 5 was produced.
Then, the tweezers were inserted into the gap of the liquid crystal cell E and slowly pulled up to peel the liquid crystal film 5 from the liquid crystal cell E. As a result, the liquid crystal film 5 was obtained.
The obtained liquid crystal film 5 had a red color and had elasticity. Further, when the liquid crystal film 5 was pressed with a finger, the color changed to blue. Therefore, in Example 8, it was found that the liquid crystal film 5 can be produced in which the orientation is fixed at the wavelength of Bragg reflection and the reflected light having a wavelength corresponding to the stress can be obtained by applying a mechanical stress.

[Example 9]
<Preparation of liquid crystal film 6>
In the liquid crystal cell E, the liquid crystal film 6 and the liquid crystal cell F were obtained in the same manner as in Example 8 except that the thickness of the liquid crystal material 3 was changed to 500 μm.
The obtained liquid crystal film 6 had a red color and had elasticity. The evaluation of the elasticity of the liquid crystal film 6 will be described later.

<Evaluation>
(Optical characteristics of liquid crystal material and liquid crystal film)
-Measurement of FT-IR spectrum-
Using the liquid crystal material 3 (HPC-Ac · Ca / BuE) obtained in Example 3, the FT-IR spectrum was measured by FT-IR (infrared total reflection absorption measurement method: ATR method). The results are shown in FIG. FIG. 2 is an FT-IR spectrum of Example 3.
As shown in FIG. 2, the peak of C = O expansion / contraction vibration appeared strongly near 1730 cm ^-1 . In addition, the peak of OH expansion and contraction vibration near 3300 cm ^{-1 to} 3600 cm ^-1 decreased. Therefore, it was confirmed that the liquid crystal material 3 (HPC-Ac · Ca / BuE) of Example 3 had a sufficient degree of acryloyl carbamate formation and a degree of butyryl esterification.

-Measurement of transmission spectrum (before UV irradiation)-
Using the liquid crystal cell A (liquid crystal material 1: HPC-Ac / BuE (1)) and the liquid crystal cell E (liquid crystal material 3: HPC-Ac · Ca / BuE) obtained in Examples 4 and 8 before irradiation with ultraviolet rays. , The transmission spectrum in the heating process was measured. The results are shown in FIGS. 3 and 4. FIG. 3 is a transmission spectrum of the liquid crystal cell A provided with the liquid crystal material 1 in the temperature raising process, and FIG. 4 is a transmission spectrum of the liquid crystal cell E provided with the liquid crystal material 3 in the temperature rising process.
As shown in FIG. 3, in the liquid crystal cell A provided with the liquid crystal material 1, it was found that the wavelength of Bragg reflection shifts from 390 nm to 720 nm by a long wavelength in the process of raising the temperature from 60 ° C. to 120 ° C.
As shown in FIG. 4, in the liquid crystal cell E provided with the liquid crystal material 3, it was found that the wavelength of Bragg reflection shifts from 400 nm to 780 nm in the process of raising the temperature from 55 ° C to 125 ° C.
It is considered that this is because the molecular helix pitch of the cholesteric liquid crystal is expanded by the external stimulus by heat. Therefore, the liquid crystal cell A before ultraviolet irradiation obtained in Example 4 (liquid crystal material 1: HPC-Ac / BuE (1)) and the liquid crystal cell E before ultraviolet irradiation obtained in Example 8 (liquid crystal material 3: liquid crystal material 3:). HPC-Ac · Ca / BuE) was found to exhibit thermotropic liquid crystallinity.

-Fixed orientation at different Bragg reflection wavelengths-
The transmission spectrum was measured using the liquid crystal cells A to C (all liquid crystal materials 1: HPC-Ac / BuE (1)) provided with the liquid crystal films 1 to 3 obtained in Examples 4 to 6. The results are shown in FIGS. 5-7. FIG. 5 is a transmission spectrum of Example 4 (liquid crystal film 1), FIG. 6 is a transmission spectrum of Example 5 (liquid crystal film 2), and FIG. 7 is a transmission spectrum of Example 6 (liquid crystal film 3). ..
As shown in FIG. 5, in Example 4, a liquid crystal film 1 having a fixed orientation in a wavelength region in which Bragg reflection exhibits red (around 600 nm) and a wavelength region in which Bragg reflection exhibits green (around 530 nm) was obtained.
As shown in FIG. 6, in Example 5, a liquid crystal film 2 having a fixed orientation in a wavelength region in which Bragg reflection exhibits green (around 530 nm) and a wavelength region in which Bragg reflection exhibits blue (around 420 nm) was obtained.
As shown in FIG. 7, in Example 6, a liquid crystal film 3 having a fixed orientation in a wavelength region in which Bragg reflection exhibits red color (around 600 nm) and a wavelength region in which Bragg reflection exhibits blue color (around 450 nm) was obtained.
From the above results, it was confirmed that in the liquid crystal films 1 to 3 of Examples 4 to 6, the orientation was fixed by different Bragg reflections (three primary colors).

-Measurement of transmission spectrum before and after UV irradiation-
Using the liquid crystal cell E (thickness of liquid crystal film: 200 μm, HPC-Ac · Ca / BuE) obtained in Example 8, before irradiating the liquid crystal cell E with ultraviolet rays of 365 nm for 10 minutes while maintaining the liquid crystal cell E at 100 ° C. Later, the transmission spectrum was measured. The results are shown in FIG. FIG. 8 is a transmission spectrum of Example 8 before and after irradiation with ultraviolet rays.
As shown in FIG. 8, in Example 8, the wavelength of Bragg reflection was 615 nm before irradiation with ultraviolet rays, but the wavelength was shifted to 569 nm after irradiation. It is considered that this is because the C = C bond of the acryloyl group is cleaved by the irradiation with ultraviolet rays, the acryloyl groups introduced into the HPC side chain are cross-linked, and the molecular spiral pitch is contracted.
Furthermore, it was found that even if the temperature of Example 8 after irradiation with ultraviolet rays was lowered from 100 ° C. to room temperature, the reflected wavelength hardly changed. This suggested that the molecular helix structure of HPC-Ac · Ca / BuE was immobilized.

(Elasticity and elastic modulus of liquid crystal film)
-Application of mechanical stress-
Pressure (mechanical stress) was applied to the liquid crystal film 6 (HPC-Ac · Ca / BuE) obtained in Example 9 with a transparent plastic spoon. As a result, it was visually confirmed that the color of the liquid crystal film 6 changed from red to blue in Bragg reflection. This suggests that the wavelength of Bragg reflection shifts to the short wavelength side and the spiral pitch contracts. Further, the liquid crystal film 6 has elasticity and can be bent.

-Repeat application and relaxation of mechanical stress-
Mechanical stress was repeatedly applied and relaxed to the liquid crystal film 4 (HPC-Ac / BuE (2)) obtained in Example 7. The results are shown in FIG. FIG. 9 is a graph showing the relationship between the number of cycles of applying and relaxing mechanical stress and the Bragg reflection wavelength in Example 7.
As shown in FIG. 9, it was found that even if the mechanical stress was repeatedly applied (shifted to the short wavelength side) and relaxed (shifted to the long wavelength side), the original Bragg reflection wavelength was reversibly returned. That is, it was found that the liquid crystal film 4 has elasticity and can reversibly modulate the wavelength of Bragg reflection.

The liquid crystal material and liquid crystal film of the present invention can be used not only as a display material for a liquid crystal display element, but also as a photonic device (various sensors using liquid crystal properties (distortion sensor, wearable sensor, etc.), optical element, etc.). It can be used. Therefore, it contributes to the manufacture and sale of display materials for liquid crystal display elements and parts used for photonic devices, and has industrial applicability.

10, 10A liquid crystal cell, 12 first substrate, 14 second substrate, 16 photomask, 18 liquid crystal material, 20 liquid crystal film

Claims (19)

It contains a cellulose derivative having a molecular structure represented by the following general formula (1A ), and contains
The average number of hydroxyl groups per monomer unit is 0.3 or less.
Degree of substitution per monomer unit group having an unsaturated double bond state, and are 0.01 to 2.0,
The group having an unsaturated double bond, Ru Oh a group represented by the following general formula (1C), a liquid crystal material.



(In the general formula (1A), X ¹¹ represents − (R ¹⁴ −O) _h −, and X ¹² and X ¹³ are independently single bonds, alkylene groups, − (R ¹⁴ −O) _h −. , ^{or, -C (= O) -R 15} - ^represents, R ^{11, R 12} and ^{R 13} each independently represent a hydrogen atom, a group having an unsaturated double bond, or a hydrophobic group, R ¹⁴ and R ¹⁵ each independently represent 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.)


(In the general formula (1C), R ^1C represents a hydrogen atom or a methyl group, X ¹⁸ is a single bond, a linear or branched alkylene group having 1 to 18 carbon atoms, and a cycloalkylene group having 3 to 18 carbon atoms. , An arylene group having 6 to 18 carbon atoms, or a linking group in which one or two or more selected from the group consisting of -O-, -NH-, -S-, and -C (= O)-is linked. Represented, p1 represents an integer of 1 or 2. However, the valence of X ¹⁸ is p1 + 1. ** is combined with X ¹¹ , X ¹² , or X ^{13 in} the above general formula (1A). Represents a portion or a portion of the cellulose skeleton that binds to an oxygen atom at the 2-position, 3-position, or 6-position, or in the above general formula (1B), a portion that binds to X ¹⁶ or X ¹⁷ , or a cellulose skeleton Represents the part that bonds with the oxygen atom at the 3rd or 6th position of.) The ratio of the degree of substitution of the unsaturated double bond per monomer unit to the degree of substitution of the hydrophobic group per monomer unit (the group having the unsaturated double bond / the hydrophobic group) is The liquid crystal material according to claim 1, which is 3.0 × 10 ^-3 or more and 2.0 or less. The liquid crystal material according to claim 1 or 2, wherein the molecular structure represented by the general formula (1A) is a molecular structure represented by the following general formula (1A-1).



(In the general formula (1A-1), R ¹ represents -CH _2- CH _2- or -CH _2- CH (CH ₃ )-, and R ¹¹ , R ¹² and R ¹³ are independent of each other. , Hydrogen atom, a group having an unsaturated double bond, or a hydrophobic group, m1, t1 and r1 independently represent an integer of 0 or more and 10 or less, and n13 is an integer of 2 or more and 800 or less. Represents.) Before SL hydrophobic group, 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, carbon A linear or branched acyl group having a number of 2 to 18, a linear or branched alkoxy group having 1 to 18 carbon atoms, a carboxylic acid ester group represented by −COOR ^1A , or a halogen atom, wherein R ^1A is The present invention according to any one of claims 1 to 3, which is 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. The liquid crystal material described . The liquid crystal according to claim 4, wherein in the general formula (1C), X ¹⁸ is a single bond or -C (= O) -NH- (CH ₂ ) _2- O-, and p1 is 1. material. The liquid crystal material according to claim 4 or 5, wherein the hydrophobic group is a linear or branched acyl group having 2 to 4 carbon atoms. The liquid crystal material according to claim 6, wherein the acyl group is a linear or branched butyryl group. Has a three-dimensional structure
It contains a cellulose derivative having a molecular structure represented by the following general formula (2A ), and contains
The average number of hydroxyl groups per monomer unit is 0.3 or less.
The cellulose derivative is seen containing a group having a linking group linking monomer units together,
A liquid crystal film in which the group having the linking group is a group represented by the following general formula (2C) .



(In the general formula (2A), X ²¹ represents − (R ^24- O) _j −, and −X ²² and X ²³ are independently single bond, alkylene group, − (R ^24- O) _j. -, ^{or, -C (= O) -R 25} - ^represents, R ^{21, R 22} and ^{R 23} each independently represent a hydrogen atom, a group having the linkage group, or a hydrophobic radical, R ²⁴ and R ²⁵ each independently represent an alkylene group, j represents an integer of 1 or more and 10 or less, and n21 represents an integer of 2 or more and 800 or less.)


(In the general formula (2C), R ^2C represents a hydrogen atom or a methyl group, and X ²⁸ is a single bond, a linear or branched alkylene group having 1 to 18 carbon atoms, or a cycloalkylene group having 3 to 18 carbon atoms. , An arylene group having 6 to 18 carbon atoms, or a linking group in which one or two or more selected from the group consisting of -O-, -NH-, -S-, and -C (= O)-is linked. Represented, p2 represents an integer of 1 or 2. However, the valence of X ²⁸ is p2 + 1. * Represents the bond position when the monomer units are linked. ** represents the above general formula. In (2A), the portion that binds to X ²¹ , X ²² , or X ²³ , or the portion that binds to an oxygen atom at the 2, 3, or 6 position of the cellulose skeleton is represented, or the above general formula (2B) ), Represents a portion that binds to X ²⁶ or X ²⁷ , or a portion that binds to an oxygen atom at the 3- or 6-position of the cellulose skeleton.) The liquid crystal film according to claim 8, wherein the degree of substitution of the hydrophobic group per monomer unit is 1.0 or more and 2.9 or less. The liquid crystal film according to claim 8 or 9, wherein the molecular structure represented by the general formula (2A) is a molecular structure represented by the following general formula (2A-1).



(In the general formula (2A-1), R ² represents -CH _2- CH _2- or -CH _2- CH (CH ₃ )-, and R ²¹ , R ²² and R ²³ are independent of each other. , Hydrogen atom, the group having the linking group, or the hydrophobic group, m2, t2 and r2 independently represent an integer of 0 or more and 10 or less, and n23 represents an integer of 2 or more and 800 or less. .) Before SL hydrophobic group, 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, carbon A linear or branched acyl group having a number of 2 to 18, a linear or branched alkoxy group having 1 to 18 carbon atoms, a carboxylic acid ester group represented by −COOR ^2A , or a halogen atom, wherein the R ^2A is The present invention according to any one of claims 8 to 10, which is 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. The liquid crystal film described . The liquid crystal according to claim 11, wherein in the general formula (2C), X ²⁸ is a single bond or -C (= O) -NH- (CH ₂ ) _2- O-, and p2 is 1. the film. The liquid crystal film according to claim 11 or 12, wherein the hydrophobic group is a linear or branched acyl group having 2 to 4 carbon atoms. The liquid crystal film according to claim 13, wherein the acyl group is a linear or branched butyryl group. The step of applying the liquid crystal material according to any one of claims 1 to 7 onto a substrate, and
A step of applying heat or a step of irradiating ultraviolet rays to the liquid crystal material applied on the substrate,
A method for producing a liquid crystal film. A sensor comprising the liquid crystal film according to any one of claims 8 to 14. The sensor according to claim 16, which is a strain sensor that detects the strain of an object. The sensor according to claim 16, which is a wearable sensor that detects biological information. An optical element comprising the liquid crystal film according to any one of claims 8 to 14.