JP5360794B2 - Sugar alcohol ester or ether, cholesteric liquid crystal additive, liquid crystal composition and display element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new additive to be added to a cholesteric liquid crystal and to obtain a liquid crystal display element produced by the addition of the additive. <P>SOLUTION: The new sugar alcohol ester or ether is represented by general formula (1) [wherein R is a group represented by general formula (2) (wherein A is an aliphatic group; B and C are each a group selected from an ester, an ether and a methylene group or A-B- is a group selected from a hydrogen group or a methyl group; D is a bifunctional saturated hydrocarbon group; E is a group selected from a carbonyl group, a methylene group and an oxycarbonyl ethylene carbonyl group; and n is an integer of 1-6)]. The liquid crystal composition and the display element each comprises the same. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a sugar alcohol ester or ether, a cholesteric liquid crystal additive, a liquid crystal composition, and a liquid crystal display device.

Currently, a color display that uses light emission of a substance or a light absorption action of a dye or a pigment is used. On the other hand, there is known a method for displaying a color using light interference caused by spontaneous aggregation of liquid crystal molecules. In the latter case, it is known to use a cholesteric liquid crystal and exhibit a color due to interference by the helical periodic structure. However, it was found that the color reflected by the cholesteric liquid crystal is not suitable as a medium for a recording display element because it changes with temperature. Therefore, the present inventors have invented that the interference color can be stably fixed at room temperature in a glass state by using a liquid crystal composed of molecules having a molecular weight of 2000 or less and in the range of about 1000. Various colors can be fixed by freezing the molecular arrangement by vitrification after the cholesteric reflection color is controlled by adding a few percent of the azobenzene derivative, which is a photochromic compound. The invention which can perform the color display using what it can do was performed (nonpatent literature 1, nonpatent literature 2). Since the reflected color of the light irradiation section can be continuously changed depending on the amount of light irradiation, full color display control can be performed using this. In the subsequent operation, by performing a rapid cooling operation below the glass transition temperature, an arbitrary reflected color can be maintained in the glassy solid, so that it can be stably fixed at room temperature. It was also found that erasing and rewriting can be performed once by heating to 130 ° C. or higher.
In the above case, not only can a full color be recorded and displayed with a single layer, but also the recording is not changed at all by room light despite being a reversible optical recording material. Furthermore, a laser scanning exposure apparatus has been developed, and a color image output from a personal computer can be directly recorded on this material.

When the photochromic compound is added in an amount of 10% by weight or more in order to improve the photoresponsiveness, crystallization after color fixation is promoted, which causes a problem that the fixed color cannot be stably stored at room temperature. In order to solve this problem, the present inventors have introduced a substituent having a structure similar to that of a liquid crystalline medium (specifically, cholesteryl group) into an azobenzene derivative, or making the additive a polymer type is effective. As a result, the inventors have completed new inventions that enable stable storage of fixed colors at room temperature (Patent Documents 1 and 2).
In addition, the present inventors have found that when an acrylate oligomer having a mesogen in the side chain is added as a photoresponsive polymer type additive, the change in reflected color can be greatly increased. (Non-patent Document 3). The reason can be explained by considering a mechanism capable of causing a pitch shift in the cholesteric liquid crystal CD8 used as a base material. It has been confirmed that the cholesteric liquid crystal phase of CD8 has a dynamic smectic domain on the low temperature side, and when the layer structure derived from this domain is emphasized, the pitch shift can be increased. (Non-Patent Document 4).

In these cholesteric liquid crystals, if there is an additive capable of stabilizing the dynamic smectic structure, it is considered that the pitch of the cholesteric liquid crystals can be greatly shifted. In the oligomer additive, there are a plurality of mesogens bonded to the side chain, and these mesogens can have an orientation state similar to that of liquid crystal molecules forming a smectic layer structure in one molecule. Conceivable. Therefore, an additive that can maintain a structure similar to the smectic layer structure in a molecularly dispersed state in the base liquid crystal is effective in stabilizing the dynamic smectic domain in the cholesteric phase. It can be explained that a large pitch shift can be brought about.
When an oligomer type additive which is a polymer type additive is used, a large pitch shift can be brought about in the liquid crystal, so that it can be said that the addition amount is small. The molecular weight of the additive itself exceeds 1000, and even when mixed with the liquid crystal, it hardly causes the glass transition point of the base liquid crystal to be lowered. For these reasons, a thermally stable liquid crystal composition can be obtained.
Among oligomers of oligomer type additives, those having a polymerization degree of 6 to 10 showed the largest pitch shift. It was also found that the molecular weight of these oligomers can be controlled by adding a chain transfer agent to the usual radical polymerization reaction and adjusting the amount.

It has been found that using an oligomer type additive can be an effective means, but it has been found that the oligomer type additive has the following problems. Specifically, it is as follows.
(1) Since the oligomer type additive obtained by polymerization is an oligomer, molecular weight distribution cannot be avoided and it is difficult to synthesize one having the same structure and composition. It is difficult to obtain a uniform composition even when added to (2). When the degree of polymerization is reduced to 6 to 10 as an oligomer, the reaction yield of the oligomer type additive is not good depending on the chain transfer reaction, and the molecular weight is small. Therefore, many parts are lost in the reprecipitation purification process, and it is considered that the purification yield is not good. Assuming this, it is not always convenient when used, and (3) the molecular weight of the oligomer obtained by lot varies depending on the scale of oligomer production and the purity of raw materials used. (4) There is a difference in each terminal structure between the initial polymer obtained by polymerization initiated by the chain transfer agent used for oligomer production and the oligomer polymer after initiation by the reaction initiator. There are a mixture obtained by these different ones, and a uniform product cannot be obtained after all, and (5) it is expected that there is a difference in the other terminal structure because a plurality of polymerization termination reactions are considered.
From this, it is difficult to obtain an oligomer-type additive having a uniform composition composed of specific components, so even if it can be uniformly mixed when added to a liquid crystal, there are variations in the original additive Therefore, it is considered that the liquid crystal composition cannot avoid nonuniformity.

Because of this, it is a novel additive that replaces the oligomer-type additive, and can maintain a structure similar to the smectic layer structure in a state where the uniform additive is uniformly dispersed in the base liquid crystal. It is a novel additive that can be synthesized with good yield and reproducibility by shifting the cholesteric pitch greatly, stable at room temperature or higher after fixing the recorded image, color control from infrared to blue to red is possible. The appearance was desired.
JP 2001-233893 A JP 2005-82604 A N. Tamaoki, S .; Song, M .; Moriyama, H .; Matsuda, Advanced Materials, 12, 94-97 (2000). M.M. Moriyama, S .; Song, H .; Matsuda, N .; Tamaoki, J. et al. Mater. Chem. 11, 1003-1010 (2001) H. Akiyama, V .; Ajay Mallia, N.A. Tamaoki, Adv. Funct. Mater. 2006, 16, 477-484 M.M. Kidowaki, M .; Moriyama, M .; Wada, N .; Tamaoki, j. Phys. Chem. B 2003, 107, 12054

The present inventors have developed a novel additive to be added to a cholesteric liquid crystal that is not in a polymer state, and a liquid crystal display device obtained by adding the additive, aiming to solve the problems of the oligomer type additive We have made extensive research on providing
In proceeding with this research, the following were considered against the background of conventional technology.
The optimum molecular structure of the additive to be added to the cholesteric liquid crystal has a molecular weight of a so-called oligomer or lower molecular weight, and the conclusion is that a molecular structure containing oligomer-like components is effective. In this case, if the structure has a plurality of mesogens bonded to the side surfaces, it is considered that these mesogens can have the same orientation as the smectic layer structure in one molecule. In this case, in the state where uniform molecules are dispersed in the base liquid crystal, like the oligomer, it is effective in stabilizing the dynamic smectic domain in the cholesteric phase, and is expected to bring about a large pitch shift. . Furthermore, it is not considered that the glass transition temperature is lowered as a mixture.

Based on the above consideration, the novel additive selects sugar alcohol as a molecule having a molecular weight similar to that of an oligomer, and when a sugar alcohol ester or ether obtained by substituting the hydroxyl group of sugar alcohol with a plurality of mesogens, In terms, oligomer-like ones can be obtained.
Since molecules having this molecular structure are produced without using a polymerization reaction, the properties are naturally obtained in a uniform state. Even if mixed with other substances, it can be mixed uniformly. Therefore, when mixed with the cholesteric liquid crystal, the molecules are uniformly dispersed and a compatible liquid crystal composition can be obtained. The synthesis yield using the finally obtained additive is improved. Since the sugar alcohol ester or ether is used as described above, it is similar to an oligomer and not an oligomer type additive. In this way, a novel sugar alcohol ester or ether was newly invented, and when this was actually used, the present invention was confirmed by confirming that the problems found with oligomer-type additives were solved. Completed.

一般式（２）で示される式中、Ａは炭素数１〜１５の脂肪族基、Ｂ及びＣはエステル、エーテル、メチレン基から選ばれる基、又はＡ−Ｂ−で１つの水素基若しくはメチル基から選ばれる基、Ｄは炭素数２から１６の2価の飽和炭化水素基、Ｅはカルボニル基、メチレン基、オキシカルボニルエチレンカルボニル基から選ばれる基、ｎは１〜６の整数を示す。） In other words, the present inventors have succeeded in producing a sugar alcohol ester or ether represented by the following general formula (1) as a novel substance, and this sugar alcohol ester or ether is added to the liquid crystal of cholesteric liquid crystal due to its properties. It has been found to be effective as an agent.

In the formula represented by the general formula (2), A is an aliphatic group having 1 to 15 carbon atoms, B and C are groups selected from an ester, an ether, and a methylene group, or one hydrogen group or methyl in AB- A group selected from a group, D is a divalent saturated hydrocarbon group having 2 to 16 carbon atoms, E is a group selected from a carbonyl group, a methylene group and an oxycarbonylethylenecarbonyl group, and n is an integer of 1 to 6. )

（一般式（３）中、Ｆは水素基、コレステリルオキシカルボニル基から選ばれる基、Ｇは炭素数１〜１５の２価の飽和炭化水素基、Ｈはカルボニル基、メチレン基、オキシカルボニルエチレンカルボニル基から選ばれる基を表す。） Of the R groups n + 2 of the sugar alcohol ester or ether represented by the general formula (1), 1 to n + 1 groups may be substituted with the group of the general formula (3).

(In general formula (3), F is a group selected from a hydrogen group and a cholesteryloxycarbonyl group, G is a divalent saturated hydrocarbon group having 1 to 15 carbon atoms, H is a carbonyl group, a methylene group, and oxycarbonylethylenecarbonyl. Represents a group selected from groups.)

As a result, a liquid crystal composition obtained by adding the novel sugar alcohol ester or ether as an additive for liquid crystal to a liquid crystal compound having a glass transition temperature of 35 ° C. or higher and a liquid crystal phase at a temperature of the glass transition temperature or higher. The liquid crystal compound and the additive for liquid crystal become a liquid crystal composition in a compatible state. Specifically, a more uniform and stable composition can be formed as compared with a liquid crystal composition obtained by adding a conventional oligomer type additive.
When the glass transition temperature of the liquid crystal composition is 35 ° C. or higher, and preferably the overall glass transition temperature of the mixture is 70 ° C. or higher and 130 ° C. or lower, a stable cholesteric liquid crystal phase is produced in a pitch-shifted state at a temperature higher than the glass transition temperature. It can be held, has a good photoresponsiveness to the irradiated light, and the reflected color produced in response becomes an all-color liquid crystal fixed at a glass temperature or lower.
For example, the reflected light wavelength is 700 nm or more before the display element is irradiated with ultraviolet rays, and the reflected color can be changed from red to blue by the irradiation of ultraviolet rays, and the reflected light is changed. The color can be fixed in the glass state. In such a case, it is possible to maintain a state in which the reflected color does not change even when heated at 70 ° C. for 30 minutes.

  According to the present invention, a novel sugar alcohol ester or ether can be obtained. By adding this novel sugar alcohol ester or ether to the cholesteric liquid crystal phase, it is possible to disperse the uniform additive in a uniform state as compared with the case of the liquid crystal mixture obtained by adding the conventional oligomer type additive. Therefore, a stable and reproducible liquid crystal composition can be formed. Since no polymerization reaction is used in the production of the additive to be used, the problems of conventional oligomer additives can be solved. Specifically, while the low molecular weight oligomer type is about 4%, the sugar alcohol ester or ether of the present invention gives a result of 15% or more when starting from the same raw material, and the synthesis yield is greatly increased. Has been improved. The pitch shift effect by this compound is comparable to that of the oligomer type, and excellent performance as an additive is maintained. Furthermore, the fixed color can be stably stored even after the color is fixed.

一般式（２）のＡは炭素数１から１５の脂肪族基、Ｂ及びＣはエステル、エーテル、メチレン基から選ばれる基、Ａ−Ｂ−で１つの水素基、又はメチル基から選ばれる基、Ｄは炭素数２〜１６の２価の飽和炭化水素基、Ｅはカルボニル基、メチレン基、オキシカルボニルエチレンカルボニル基から選ばれる基、ｎは１〜６の整数を示す。） The sugar alcohol ester or ether of the present invention is represented by the general formula (1).

A in the general formula (2) is an aliphatic group having 1 to 15 carbon atoms, B and C are groups selected from esters, ethers, methylene groups, one hydrogen group in AB-, or a group selected from methyl groups , D is a divalent saturated hydrocarbon group having 2 to 16 carbon atoms, E is a group selected from a carbonyl group, a methylene group and an oxycarbonylethylenecarbonyl group, and n is an integer of 1 to 6. )

The aliphatic hydrocarbon group having 1 to 15 carbon atoms includes chain and cyclic saturated hydrocarbon groups or unsaturated aliphatic hydrocarbon groups.
The chain aliphatic hydrocarbon group includes an alkyl group and an alkenyl group. The alkyl group having 1 to 15 carbon atoms is a linear or branched alkyl group.
Specific examples thereof include methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, t-butyl, n-pentyl, i-pentyl, t-pentyl, n-hexyl, i-hexyl, t-hexyl, n-heptyl, i-heptyl, t-heptyl, n-octyl, i-octyl, t-octyl, n-nonyl, i-nonyl, t-nonyl, n-decyl, i-decyl , T-decyl, n-undecyl, i-undecyl, t-undecyl, n-dodecyl, i-dodecyl, t-dodecyl, n-tridecyl, i-tridecyl, t-tridecyl,
Examples thereof include n-tetradecacil, i-tetradecacil, t-tetradecacil, n-pentadecacil, i-pentadecacil, t-pentadecacil and the like.
The alkenyl group having 2 to 15 carbon atoms is a linear or branched alkenyl group.
Specific examples thereof include ethenyl, n-propenyl, i-propenyl, n-butynyl, i-butynyl, t-butynyl, n-pentynyl, i-pentynyl, t-pentynyl, n-hexenyl, i-hexenyl, t- Hexenyl, n-heptynyl, i-heptynyl, t-heptynyl, n-octynyl, i-octynyl, t-octynyl, n-nonenyl, i-nonenyl, t-nonenyl, n-decanonyl, i-decanonyl, t -Decanonyl, n-undecynyl, i-undecynyl, t-undecyl, n-dodecynyl, i-dodecynyl, t-dodecynyl, n-tridecanyl, i-tridecanyl, t-tridecanyl, n-tetradecanyl, i-tetradecanyl, t-tetradecanyl N-pentadecanyl, i-pentadecanyl, t-pentadecanyl, etc. I can make it.
Cycloaliphatic hydrocarbon groups include cycloalkyl groups and cycloalkenyl groups. The carbon number is 5-15, Preferably it is 6-12. Specific examples thereof include, for example, cyclopentyl, cyclohexyl, cyclohexenyl, cyclooctyl, cyclohexylmethyl, cyclohexyloctyl and the like.
The ester group may be a bond of either a —COO (CH ₂ ) m — group or a —OCO (CH ₂ ) m — group (m is an integer of 1 to 5).
Ether groups are -O _(CH 2) m-groups (m is an integer of 1 to 5).
The divalent saturated hydrocarbon group is a methylene group, an ethylene group or a polymethylene group (3 to 15 carbon atoms).
The azobenzene group may have a substituent substituted with an alkyl group or a halogen atom on two benzene rings forming azobenzene.

  In order to produce the sugar alcohol ester or ether represented by the general formula (1), the compound having the azobenzene compound represented by the general formula (2) is reacted with the sugar alcohol.

The raw material used in the above reaction is as follows.
I The precursor of the precursor compound giving the azobenzene moiety represented by the general formula (2) as one raw material includes carboxylic acid, carboxylic acid ester, alcohol, halide, acid halide and the like. Specifically, the following compounds are exemplified.

When these compounds are produced, a derivative of the (corresponding 4-hydroxy) azobenzene compound (a compound having substituents A to C or D of the compound represented by the general formula (2)) and a substituent E, or Prepared by reacting a derivative of a compound having D and E.
Specifically, the following reaction is used.
(Ii) When reacting an azobenzene derivative with a halogenated carboxylic acid ester In this case, the following reactions are included.
4-Hexyl-4′-hydroxyazobenzene and ethyl 6-bromohexanoate are reacted in the presence of a solvent under alkaline conditions (Example 1).
(B) When reacting an azobenzene derivative with a halogenated carboxylic acid In this case, the following cases are included (Example 2 and Example 6).
4-Hexyl-4′-hydroxyazobenzene and bromoundecanoic acid are reacted under alkaline conditions in the presence of a solvent.
(C) When reacting an azobenzene derivative with a halogenated alcohol In this case, the following cases are included.
4-Hexyl-4′-hydroxyazobenzene and bromoundecanol are reacted under alkaline conditions in the presence of a solvent.
(D) When reacting an azobenzene derivative with an alkyl dihalide In this case, the following cases are included.
4-Hexyl-4′-hydroxyazobenzene and dibromododecane are reacted under alkaline conditions in the presence of a solvent.

II The other is as follows.
The sugar alcohol used is a chain polyhydric alcohol in which a carbonyl group composed of an aldehyde group and a ketone group of a sugar is reduced, and also includes a cyclic sugar alcohol. A sugar having 3 to 6 carbon atoms of n is employed. Specifically, glycerin is a trit in the case of triose, tetrit (D, L-trait, D, L-trait erythrite, erythrite, etc.) in the case of tetrose, and pentet (D, in the case of pentose). L-arabit, D, L-arabit rebit, rebit, xylit, D, L-rigit, hexit, D, L-glucit, D, L-sorbit, D, L-mannit, D, L-exit, D , L-sorbose, D, L-grit, D, L-talit, galactite, alit, altrit, etc.).

The azobenzene derivative of I and the sugar alcohol of II are reacted at room temperature in the presence of a solvent.
Specifically, Examples 1, 2 and 6 show.

（３）式中Ｆは水素基、コレステリルオキシカルボニル基から選ばれる基、Ｇは炭素数１〜１５の２価の飽和炭化水素基、Ｈはカルボニル基、メチレン基、オキシカルボニルエチレンカルボニル基から選ばれる基を表す。） In the sugar alcohol ester or ether of the present invention, 1 to n + 1 groups out of n + 2 R groups of the sugar alcohol ester or ether represented by the general formula (1) are represented by the group of the general formula (3). It may be a substituted sugar alcohol ester or ether.

(3) In the formula, F is a group selected from a hydrogen group and a cholesteryloxycarbonyl group, G is a divalent saturated hydrocarbon group having 1 to 15 carbon atoms, H is a carbonyl group, a methylene group, and an oxycarbonylethylenecarbonyl group. Represents a group. )

The divalent saturated hydrocarbon group is a methylene group, an ethylene group or a polymethylene group (3 to 15 carbon atoms).
The cholesteryloxycarbonyl group is a group in which an oxycarbonyl group is bonded to the terminal of the cholesteryl group by substitution.

  In the sugar alcohol ester or ether, 1 to n + 1 groups out of n + 2 R groups of the sugar alcohol ester or ether represented by the general formula (1) are substituted with the group of the general formula (3). When producing a sugar alcohol ester or ether, a compound having a group represented by the general formula (3) is produced by reacting the sugar alcohol represented by the general formula (1).

A compound having a group represented by the general formula (3) are as exemplified below.

The synthesis reaction of the compound (a) is as follows.
Cholesterol and dicarboxylic acid are reacted with a condensing agent typified by DCC.
Cholesterol and dicarboxylic acid anhydride are reacted.

前記式中、Ｚ及びＹはそれぞれ独立してコレステリル基、水素原子又はアルキル基を示す。その少なくともいずれか、一方はコレステリル基である。この場合のアルキル基は、炭素数２〜３０、好ましくは２〜１８のアルキル基である。前記Ｒは炭素数２から３０の二価有機基を示す。この場合の二価有機基には、脂肪族炭化水素基及び芳香族炭化水素基が包含される。また、脂肪族基には、鎖状又は環状の飽和もしくは不飽和の二価脂肪族炭化水素基が包含され、その炭素数は２〜３０、好ましくは２〜２２である。不飽和脂肪族炭化水素基には、２重結合や３重結合を持ったものが包含される。二価芳香族炭化水素基には、１つのベンゼン環を有する単環芳香族炭化水素（ベンゼン、トルエン、キシレン等）から誘導される二価炭化水素基及び２つ以上、通常、２〜４子のベンゼン環を有する多環芳香族炭化水素（ナフタレン、ビフェニル、ターフェニル等）から誘導される二価炭化水素基が包含される（これらについては、本発明者らによる特開２００５−８２６０４号公報、特開２０００−８９３９８号公報、特開平１１−２４０２７号公報に記載されている。）。 The cholesteric liquid crystal used in the present invention is a liquid crystal that has a glass transition temperature of 35 ° C. or higher and takes a liquid crystal phase at a temperature higher than the glass transition temperature.
A cholesteric liquid crystal represented by the following general formula (4).

In the above formula, Z and Y each independently represent a cholesteryl group, a hydrogen atom or an alkyl group. At least one of them is a cholesteryl group. The alkyl group in this case is an alkyl group having 2 to 30 carbon atoms, preferably 2 to 18 carbon atoms. R represents a divalent organic group having 2 to 30 carbon atoms. In this case, the divalent organic group includes an aliphatic hydrocarbon group and an aromatic hydrocarbon group. The aliphatic group includes a linear or cyclic saturated or unsaturated divalent aliphatic hydrocarbon group, and the carbon number thereof is 2 to 30, preferably 2 to 22. Unsaturated aliphatic hydrocarbon groups include those having a double bond or a triple bond. The divalent aromatic hydrocarbon group includes a divalent hydrocarbon group derived from a monocyclic aromatic hydrocarbon (benzene, toluene, xylene, etc.) having one benzene ring, and two or more, usually 2 to 4 elements. Divalent hydrocarbon groups derived from polycyclic aromatic hydrocarbons having a benzene ring (naphthalene, biphenyl, terphenyl, etc.) are included (these are disclosed in JP-A-2005-82604 by the present inventors). JP-A-2000-89398 and JP-A-11-24027).

前記式中、ｍ及びｎは独立して１以上の整数であり、そのｍとｎとの合計は３０以下、好ましくは２０以下であり、その下限値は４程度である。
このコレステリルエステル誘導体は、Advanced Materials, 9(14), 1102(1997)に記載された方法によって合成される。すなわち、コレステロールと相当するジカルボン酸化合物及びジシクロヘキシルカルボジイミド、４−ジメチルアミノピリジンを塩化メチレン中室温下で１２時間撹拌し、得られた反応混合物から沈殿物をフィルターで分離後、溶液をシリカゲル（展開溶媒は塩化メチレン）のカラムクロマトグライフィーで精製することにより得ることができる。 The divalent organic group R is preferably an unsaturated aliphatic group represented by the following general formula (5).

In the above formula, m and n are each independently an integer of 1 or more, the sum of m and n is 30 or less, preferably 20 or less, and the lower limit is about 4.
This cholesteryl ester derivative is synthesized by the method described in Advanced Materials, 9 (14), 1102 (1997). That is, cholesterol and a corresponding dicarboxylic acid compound, dicyclohexylcarbodiimide, and 4-dimethylaminopyridine were stirred in methylene chloride at room temperature for 12 hours, and the precipitate was separated from the resulting reaction mixture with a filter, and the solution was then mixed with silica gel (developing solvent). Can be obtained by purifying with a column chromatography (methylene chloride).

In order to obtain the liquid crystal composition by adding the sugar alcohol ester or ether to the cholesteric liquid crystal represented by the general formula (4), the sugar alcohol ester or ether is 1 to 15% by weight with respect to the cholesteric liquid crystal, Preferably 3-4% by weight is added. If the amount added is less than 1% by weight, the effect cannot be expected. If the amount added exceeds 15% by weight, the transmittance decreases due to scattering and absorption due to phase separation, and a satisfactory effect is obtained. I can't. This also affects the setting of the glass transition temperature of the liquid crystal composition obtained by adding the sugar alcohol ester or ether described below.
In order to obtain a cholesteric liquid crystal composition, the sugar alcohol ester or ether represented by the general formula (1) and the liquid crystal compound are dissolved in a solvent such as dichloromethane, toluene or tetrahydrofuran at the above-mentioned ratio, and the mixture is stirred and mixed. Leave. Alternatively, the mixture is melted as it is at 130 ° C. or more without using a solvent and stirred.

The liquid crystal composition obtained by adding the sugar alcohol ester or ether to the cholesteric liquid crystal represented by the general formula (4) can have a glass transition temperature of 35 ° C. or higher, which is a preferable state. It is in the range of about 70 ° C to 130 ° C.
The sugar alcohol ester or ether is a molecule in which a mesogen with 1 similar to an oligomer is substituted and is incorporated into the sugar alcohol ester or ether, and is not in a polymer state.
When a sugar alcohol ester or ether is added, the additive having a constant molecular weight and components is kept in a uniformly dispersed state in the base liquid crystal as compared with the case where an elastomer polymer is added. After the cholesteric pitch is greatly shifted and the recorded image is fixed, it is stable at room temperature or higher, responds well to the irradiated light, and the resulting reflected color is fixed. Color control is possible from the infrared to blue to red. The reflected color corresponds to full color. In general, ultraviolet light is used as the irradiation light.

The liquid crystal composition is formed by sandwiching between two substrates. In this case, a thin glass plate or the like is usually used as the substrate, but a polymer thin film or a metal plate may be used. One of the two sheets needs to be transparent so that at least a part of the light is transmitted. As a method of sandwiching between two substrates, first, a mixture of cholesteric liquid crystal and sugar alcohol ester and ether is heated to a temperature in a molten state or a liquid crystal state, added to one substrate and then placed on the other substrate. There is a method of adding between two substrates kept in parallel by using a reduced pressure or a capillary phenomenon. The distance between the substrates is not particularly limited, but is preferably about several to 100 microns. Partial or total heating of the composition can be performed by any method such as a thermal head, a heating roll, or a laser beam. Heating that requires temperature control to the liquid crystal temperature range can be achieved by controlling the temperature of the thermal head, heating roll, etc., adjusting the intensity of the laser beam or the spot diameter, or heating the whole to a certain temperature, This is possible by lowering the temperature to the required temperature with a flat metal plate or rubber plate.
Rapid cooling to below the glass transition temperature includes a method of immersing the entire sample in a refrigerant or a cooled atmosphere, a method of bringing a part of the sample into contact with a cooled head, and the like.

  The image recording medium obtained as described above is a rewritable color image recording medium that can be recorded by light irradiation for a short time. In order to form an image using this, a composition sandwiched between substrates is irradiated with light from the transparent substrate side at a temperature at which the composition exhibits cholesteric liquid crystallinity, and then 1 ° C./second. Rapid cooling to below the glass transition temperature at the above speed. In this way, a color image can be recorded on the recording medium. The cooling rate after the light irradiation is 1 ° C./second or more, preferably 10 ° C./second or more, more preferably 40 to 60 ° C./second, and most preferably 50 ° C./second. When the cooling rate is less than 1 ° C./second, the color of the image is likely to change at the stage of fixation. For the same reason, it is desirable to shorten the time from image formation to fixation as much as possible.

The image obtained by the present invention can be erased any number of times by writing it once and then heating the whole or a part thereof to the melting point of the cholesteric liquid crystalline compound or a mixture thereof. Furthermore, in the present invention, it is possible to write another image on a medium having the image by light irradiation at a temperature exhibiting liquid crystallinity. In the image forming method of the present invention, the color can be changed simply by irradiating the photochromic compound with light that is weak enough to cause a photoisomerization reaction through a mask, and the color can be fixed by a rapid cooling operation. Since the color to be fixed depends on the amount of irradiation light, it is possible to change the desired portion to the desired color by simply controlling the amount of light. The colors that can be reproduced are limited by the type of cholesteric liquid crystal used, but two or more types of color development with different spectral components are possible.
For example, the reflected light wavelength is 700 nm or more before the display element is irradiated with ultraviolet rays, and the reflected color can be changed from red to blue by the irradiation of ultraviolet rays, and the reflected light is changed. The color can be fixed in the glass state. In such a case, it is possible to maintain a state in which the reflected color does not change even when heated at 70 ° C. for 30 minutes.

Synthesis of 1,2,3,4,5,6-O-hexa {6- [4- (4-hexylphenylazo) phenoxy] hexanoic} -D-mannitol (1) as an additive 4-hexyl- 1.7 g of 4′-hydroxyazobenzene and 1.5 g of ethyl 6-bromohexanoate are added to 10 ml of DMF, and 0.92 g of potassium carbonate is added thereto. The mixture was stirred at 80 ° C. for about 14 hours, diluted with a mixed solvent of hexane and ethyl acetate, washed with water, dried over magnesium sulfate, and concentrated. This was column-separated with normal hexane and ethyl acetate (4: 1) and then concentrated to obtain 2.40 g of ethyl 6- [4- (4-hexylphenylazo) phenoxy] hexanoate (93.5% ).
The NMR measurement results are as shown in Table 1 below.

(Table 1)
1H NMR (CDCl3, d): 0.89 (3H, t, -CH ₃ ), 1.26 (3H, t, COOCH ₂ C H ₃ ), 1.32 (6H, s, -CH _2- ), 1.53 (2H, tt, -C H ₂ -CH ₂ OAr), 1.60-1.78 (4H, m, ArCH ₂ C H _2- , -C H ₂ -CH ₂ COO-), 2.35 (2H, t, -CH ₂ COO-), 2.67 (2H, t, ArCH2-), 4.04 (2H, t, ArOC H _2- ), 4.13 (2H, q, -C H ₂ OCO-), 6.98 (2H, d, Ar-H), 7.29 (2H, d, Ar-H), 7.79 (2H, d, Ar-H), 7.88 (2H, d, Ar-H).

A solution of 2.3 g of ethyl 6- [4- (4-hexylphenylazo) phenoxy] hexanoate in 20 ml of dimethyl sulfoxide and 2.2 g of an aqueous solution of potassium hydroxide (0.9 g) was mixed at 110 ° C. for 1 hour. Stir. After adding 100 ml of water and neutralizing with acetic acid, the precipitate was separated by filtration and washed with water. This was vacuum-dried for 3 days to obtain 2.06 g of 6- [4- (4-hexylphenylazo) phenoxy] hexanoic acid (96%).
0.65 g of 6- [4- (4-hexylphenylazo) phenoxy] hexanoic acid was dissolved in 3 ml of dehydrated dichloromethane, and 1 ml of thionyl chloride was added thereto. After heating at reflux for 1 hour, the solvent and thionyl chloride were distilled off and 5 ml of dehydrated dichloromethane was added. This solution was slowly added to a liquid in which 42 mg of D-mannitol was suspended in 3 ml of dehydrated pyridine and stirred at room temperature for 4 days. Chromatographic column separation was performed using a mixed solvent of dichloromethane, hexane and ethyl acetate (25: 25: 3) as a developing solvent in the dark to obtain 0.24 g of 6-substituted product (yield 37%).
The NMR measurement results are shown in Table 2 below.

(Table 2)
1H NMR (CDCl3, d): 0.88 (18H, s, -CH ₃ ), 1.31 (36H, s, -CH _2- ), 1.54 (12H, br m, -C H ₂ -C ₂ H ₄ OAr), 1.65 (24H, br m, ArCH ₂ -C H _2- , -C H ₂ -C H ₂ -CH ₂ COO-), 1.79 (12H, br m, -C H ₂ -CH ₂ OAr), 2.35 (12H , br m, -CH ₂ COO-), 2.67 (12H, br m, ArCH _2- ), 3.98 (12 + 2H, br m, ArOCH _2- , H-1, H-6), 4.29 (2H, d , H-1 ', H-6'), 5.12 (2H, br s, H-2, H-5), 5.49 (2H, d, H-3, H-4), 6.95 (12H, br t, Ar-H), 7.28 (12H, br d, Ar-H), 7.77 (12H, br d, Ar-H), 7.85 (12H, br d, Ar-H).
MALDI-TOF-MS; 2452 (M + H ⁺ ), 2475 (M + Na ⁺ ), 2491 (M + K ⁺ )

Synthesis of additive 1,2,3,4,5,6-O-hexa {11- [4- (4-hexylphenylazo) phenoxy] undecanoic} -D-mannitol 4-hexyl-4′- 1.05 g of hydroxyazobenzene, 0.99 g of bromoundecanoic acid and 0.46 g of potassium hydroxide were dissolved in 37 ml of ethanol and stirred at 100 ° C. for 3 days. The mixture was neutralized with hydrochloric acid and acetic acid, and the precipitate was filtered off and washed with water. This was subjected to chromatographic column separation with chloroform and ethyl acetate (9: 1) to obtain 0.90 g of 11- [4- (4-hexylphenylazo) phenoxy] undecanoic acid (yield 52%) (known compound T. Seki, T. Fukuchi, K. Ichimura, Bull. Chem. Soc. Jpn. 1998, 71, 2807-2816).
0.88 g of 11- [4- (4-hexylphenylazo) phenoxy] undecanoic acid was dissolved in 3 ml of dehydrated dichloromethane, and 1 ml of thionyl chloride was added thereto. After heating at reflux for 1 hour, the solvent and thionyl chloride were distilled off and 5 ml of dehydrated dichloromethane was added. This solution was slowly added to a suspension of 3 mg of dehydrated pyridine in 50 mg of D-mannitol and stirred at room temperature for 4 days. Chromatographic column separation was carried out using a mixed solvent of dichloromethane, hexane and ethyl acetate (25: 25: 1) as a developing solvent in the dark to obtain 0.26 g of 6-substituted product (yield 33%).
NMR measurement results are shown in Table 3 below.

(Table 3)
1H NMR (CDCl3, d): 0.88 (18H, t, -CH ₃ ), 1.39 (96H, s, -CH _2- ), 1.46 (12H, tt, -C H ₂ -C ₂ H ₄ OAr), 1.62 (24H, m, -C H ₂ -CH ₂ COO-, -C H ₂ -CH ₂ Ar), 1.79 (12H, tt, -C H ₂ -CH ₂ OAr), 2.29 (12H, m, -CH ₂ COO-), 2.66 (12H, t, ArCH2-), 4.00 (12 + 2H, m, ArOCH2-, H-1, H-6), 4.28 (2H, d, H-1 ', H-6') , 5.18 (2H, br s, H-2, H-5), 5.44 (2H, d, H-3, H-4), 6.97 (12H, br t, Ar-H), 7.28 (12H, br d , Ar-H), 7.78 (12H, br d, Ar-H), 7.87 (12H, br d, Ar-H).
MALDI-TOF-MS; 2895 (M + Na ⁺ ), 2911 (M + K ⁺ )

The liquid crystal compound (compound represented by the following structural formula 6) was mixed with the additive obtained in Example 1 at 125 ° C. so as to be 4 wt%, and a glass spacer having a diameter of 5 μm was added in a small amount and two sheets. Sandwiched between the cover glass. After the molten isotropic liquid was cooled to 90 ° C., the sample was quenched with frozen water and vitrified. The cholesteric liquid crystal reflection color of this sample was determined from the measurement of UV-visible absorption spectrum. The value was shifted by about 390 nm compared with that before the addition (FIG. 1).

  In the same manner as in Example 3, the product obtained in Example 2 was mixed with the liquid crystal compound (6) so as to be 1, 2 and 3 wt%, and a sample sandwiched between two glass substrates, did. The sample was kept at 90 ° C. from the molten state and then rapidly cooled with ice water to be fixed in the glass state. The reflection band shifts (Δλ) estimated from the UV-visible absorption spectra of these samples are 30, 140, and 605 nm, respectively, in the case of 1, 2, and 3 wt% additives, which are similar to conventional oligomer additives. Was found to cause a very large pitch shift (Fig. 2).

When a sample with 3 wt% added under the conditions of Example 4 was subjected to image writing and fixation with ultraviolet rays, full color (blue, green, red) recording was possible. This sample was heated at 70 ° C. for 30 minutes, but no change was observed in the color image.
The image color changed when heated for 75 minutes. From this, it was found that the glass transition temperature of the mixture was 70 to 75 ° C.

Synthesis of additive, 1,2-O-bis {11- [4- (4-hexylphenylazo) phenoxy] undecanoic} -ethylene glycol 4.99 g of 4-hexyl-4'-hydroxyazobenzene and bromoundecanoic acid A solution prepared by dissolving 4.48 g and 1.00 g of potassium hydroxide in 26.7 ml of ethanol was refluxed for 5 days. The mixture was neutralized with hydrochloric acid, and the precipitate was filtered off and washed with water. After liquid separation, acetone and formic acid were added a little and recrystallized.
3.5 g of the obtained substance and 1.01 g of potassium hydroxide were dissolved in 7.88 g of water, 85.3 ml of DMSO and 30.1 ml of ethanol, and refluxed at 110 ° C. for 1 hour. Acetic acid was added to adjust the pH to 5, water was added, and the precipitate was filtered off and recrystallized from methanol to obtain 2.7 g of 11- [4- (4-hexylphenylazo) phenoxy] undecanoic acid (yield 47 (4%) (This is a known compound and is described in T. Seki, T. Fukuchi, K. Ichimura, Bull. Chem. Soc. Jpn. 1998, 71, 2807-2816).
0.50 g of 11- [4- (4-hexylphenylazo) phenoxy] undecanoic acid was dissolved in 1.7 ml of dehydrated dichloromethane, and 1.1 ml of thionyl chloride was added thereto. After heating at reflux for 1 hour, the solvent and thionyl chloride were distilled off, and 2.83 ml of dehydrated dichloromethane was added. This solution was slowly added to a suspension of ethylene glycol 23.3 mg in dehydrated pyridine 1.95 ml and refluxed overnight. Chromatographic column separation was performed using a mixed solvent of dichloromethane and hexane (7: 3) as a developing solvent to obtain 25.91 mg of a disubstituted product (yield 42.4%).
The NMR measurement results are as shown in the following table.

(Table 4)
1H NMR (CDCl3, δ): 0.88 (20H, t, -CH 3), 1.26 (72H, s, -CH 2 -), 1.31 (34H, s, -CH 2 -), 1.62 (11H, tt, - _{CH 2 -C 2 H 4 OAr)} , 1.80 (3H, tt, -CH2 -), 2.33 (4H, t, -CH 2) 2.67 (4H, t, -CH 2), 4.02 (4H, t, -CH _{2), 4.27 (4H, s} , -CH 2), 6.99 (4H, d, Ar-H), 7.28 (7H, d, Ar-H), 7.79 (4H, d, Ar-H), 7.88 (4H , D, Ar-H)
MALDI-TOF-MS; 960 (M + H ⁺ ), 982 (M + Na ⁺ ), 9981 (M + K ⁺ )

The liquid crystal compound (compound represented by the following structural formula 6) was mixed with the additive obtained in Example 6 at 130 ° C. so as to be 3 wt%, and a small amount of a glass spacer having a diameter of 5 μm was added. It was sandwiched between cover glasses. After the molten isotropic liquid was cooled to 90 ° C., the sample was quenched with frozen water and vitrified. The cholesteric liquid crystal reflection color of this sample was determined from the measurement of UV-visible absorption spectrum. The value was shifted by about 120 nm compared with that before the addition (FIG. 3).

In the same manner as in Example 3, the product obtained in Example 7 was mixed with the liquid crystal compound (6) so as to be 2, 3, and 4 wt%, and a sample sandwiched between two glass substrates was obtained. . The sample was kept at 90 ° C. from the molten state and then rapidly cooled with ice water to be fixed in a glass state.
The reflection band shifts (Δλ) estimated from the UV-visible absorption spectra of these samples were 20, 120, and 160 nm, respectively, when using 2, 3, and 4 wt% additives (FIG. 4). ).

    When a sample with 3 wt% added under the conditions of Example 8 was subjected to image writing and fixation with ultraviolet rays, full color (blue, green, red) recording was possible. When this sample was heated at 40 ° C. for 30 minutes, a change in the color image was observed. From this, it was found that the glass transition temperature of the mixture was around 40 ° C.

Synthesis of 1,2,3,4-O-tetra {11- [4- (4-hexylphenylazo) phenoxy] undecanoic} -l-threitol 11- [4- (4-hexylphenylazo) phenoxy] undecane 0.70 g of acid was dissolved in 2.4 ml of dehydrated dichloromethane, and 0.79 ml of thionyl chloride was added thereto. After heating at reflux for 1 hour, the solvent and thionyl chloride were distilled off, and 3.9 ml of dehydrated dichloromethane was added. This solution was slowly added to a suspension of 30.47 mg of threitol in 3.9 ml of dehydrated pyridine and refluxed for 4 days. Fraction 1 obtained by chromatographic column separation using a mixed solvent of dichloromethane and ethyl acetate (9.5: 0.5) as a developing solvent was subjected to chromatographic column separation using dichloromethane as a developing solvent to obtain 235.05 mg of a 4-substituted product. (Yield 49.2%).
The NMR measurement results are as shown in the following table.

(Table 5)
1H NMR (CDCl3, δ): 0.88 (12H, t, —CH ₃ ), 1.30 (71H, s, —CH ₂ —), 1.46 (9H, tt, —CH ₂ —C ₂ H ₄ OAr), 1.62 ( _{30H, tt, -CH 2 -CH 2} COO -), 1.80 (8H, tt, -CH 2 -), 2.29 (4H, t, -CH 2 -), 2.34 (4H, t, -CH 2 -), _{2.66 (8H, t, -CH 2} ), 4.01 (8H, t, O-CH 2 -), 4.31 (1H, d, -CH 2 -) 4.34 (1H, d, -CH 2 -), 5.34 (2H , T, H-2, H-3), 6.98 (8H, d, Ar-H), 7.28 (14H, d, Ar-H), 7.79 (H, d, Ar-H), 7.88 (H, d) , Ar-H)
MALDI-TOF-MS; 1918 (M + H ⁺ ), 1940 (M + Na ⁺ ), 1956 (M + K ⁺ )

  The liquid crystal compound (compound represented by the following structural formula 6) was mixed with the additive obtained in Example 10 at 130 ° C. so as to be 3 wt%, and a small amount of a glass spacer having a diameter of 5 μm was added. It was sandwiched between cover glasses. After the molten isotropic liquid was cooled to 90 ° C., the sample was quenched with frozen water and vitrified. The cholesteric liquid crystal reflection color of this sample was determined from the measurement of UV-visible absorption spectrum. The value was shifted by about 350 nm compared with that before the addition (FIG. 5).

  In the same manner as in Example 3, the product obtained in Example 10 was mixed with the liquid crystalline compound (6) so as to be 4 wt%, and a sample sandwiched between two glass substrates was obtained. The sample was kept at 90 ° C. from the molten state and then rapidly cooled with ice water to be fixed in the glass state. The UV-visible absorption spectrum of these samples was well scattered, and it was found that the liquid crystal had a domain structure.

When the 3 wt% added sample prepared under the conditions of Example 12 was subjected to image writing and fixation with ultraviolet rays, full color (blue, green, red) recording was possible. This sample was heated at 70 ° C. for 30 minutes, but no change was observed in the color image.
When heated at 75 ° C. for 30 minutes, the image color changed. From this, it was found that the glass transition temperature of the mixture was 70 to 75 ° C.

Synthesis of 1,2,3,4-O-tetra {11- [4- (4-hexylphenylazo) phenoxy] undecanoic} -erythritol (2) 11- [4- (4-hexylphenylazo) phenoxy] undecane 0.70 g of acid was dissolved in 2.4 ml of dehydrated dichloromethane, and 0.79 ml of thionyl chloride was added thereto. After heating at reflux for 1 hour, the solvent and thionyl chloride were distilled off, and 3.9 ml of dehydrated dichloromethane was added. This solution was slowly added to a suspension of 2.7 ml of dehydrated pyridine containing 30.5 mg of erythritol and refluxed for 2 days. Chromatographic column separation was performed using a mixed solvent of dichloromethane and ethyl acetate (9: 1) as a developing solvent to obtain 207.91 mg of a 4-substituted product (yield 43.4%).
The NMR measurement results are as shown in the following table.

(Table 6)
1H NMR (CDCl ₃ , δ): 0.88 (12H, t, —CH ₃ ), 1.30 (70H, s, —CH ₂ —), 1.46 (9H, tt, —CH ₂ —C ₂ H ₄ OAr), 1.61 _{(38H, tt, -CH 2 -CH} 2 COO -), 1.80 (8H, tt, -CH 2 -), 2.29 (4H, t, -CH 2 -), 2.33 (4H, t, -CH 2 -) , 2.66 (8H, t, -CH 2 -), 4.01 (8H, t, -CH 2 -), 4.15 (2H, d, -CH 2 -), 4.35 (2H, d, -CH 2 -), 5.28 (2H, s, H-2, H-3), 6.98 (8H, d, Ar-H), 7.28 (22H, d, Ar-H), 7.79 (4H, d, Ar-H), 7.88 (4H , D, Ar-H)
MALDI-TOF-MS; 1918 (M + H ⁺ ), 1940 (M + Na ⁺ ), 19561 (M + K ⁺ )

  The additive obtained in Example 14 was mixed with a liquid crystal compound (compound represented by the following structural formula 6) at 130 ° C. so as to be 3 wt%, a small amount of a glass spacer having a diameter of 5 μm was added, and two sheets were added. It was sandwiched between cover glasses. After the molten isotropic liquid was cooled to 90 ° C., the sample was quenched with frozen water and vitrified. The cholesteric liquid crystal reflection color of this sample was determined from the measurement of UV-visible absorption spectrum. The value was shifted by about 210 nm compared with that before the addition (FIG. 6).

  In the same manner as in Example 15, the product obtained in Example 2 was mixed with the liquid crystal compound (6) so as to be 2, 3, and 4 wt% to obtain a sample sandwiched between two glass substrates. The sample was kept at 90 ° C. from the molten state and then rapidly cooled with ice water to be fixed in the glass state. The reflection band shifts (Δλ) estimated from the UV-visible absorption spectra of these samples were 30, 210, and 115 nm for the 2, 3, and 4 wt% additives, respectively (FIG. 7).

When the 3 wt% added sample prepared under the conditions of Example 16 was subjected to image writing and fixation with ultraviolet rays, full color (blue, green, red) recording was possible. This sample was heated at 60 ° C. for 30 minutes, but no change was observed in the color image.
An image color change occurred by heating at 65 ° C. for 30 minutes. From this, it was found that the glass transition temperature of the mixture was 60 to 65 ° C.

The figure which shows the measurement result of the ultraviolet visible absorption spectrum of a reflected color. A sample is mixed with cholesteric liquid crystal in 1, 2, 3 wt%, sandwiched between two glass substrates, held at 90 ° C from the molten state, then rapidly cooled with ice water and fixed in the glass state, and the reflection estimated from the UV-visible absorption spectrum Diagram showing band shift (Δλ) The figure which shows the measurement result of the ultraviolet visible absorption spectrum of a reflected color. A sample of cholesteric liquid crystal is mixed at 2 to 3 wt%, sandwiched between two glass substrates, held at 90 ° C. from the molten state, rapidly cooled with ice water and fixed to the glass state, and the reflection band estimated from the UV-visible absorption spectrum The figure which shows shift ((DELTA) (lambda)). The figure which shows the measurement result of the ultraviolet visible absorption spectrum of a reflected color. The figure which shows the measurement result of the ultraviolet visible absorption spectrum of a reflected color. Reflection band estimated from UV-visible absorption spectrum after mixing a sample with cholesteric liquid crystal at 2, 3 and 4 wt%, sandwiching between two glass substrates, holding at 90 ° C from the molten state and then rapidly cooling with ice water The figure which shows shift ((DELTA) (lambda)).

Claims (7)

A sugar alcohol ester or ether represented by the general formula (1).

In the formula represented by the general formula (2), A is an aliphatic group having 1 to 15 carbon atoms, B and C are groups selected from esters, ethers, methylene groups, or one hydrogen group or methyl group represented by AB- A group selected from a group, D is a divalent saturated hydrocarbon group having 2 to 16 carbon atoms, E is a group selected from a carbonyl group, a methylene group and an oxycarbonylethylenecarbonyl group, and n is an integer of 1 to 6. ) Of n + 2 R groups of the sugar alcohol esters or ethers represented by the general formula (1), according to claim, characterized in that the 1 to n + 1 groups are substituted by groups of the general formula (3) The sugar alcohol ester or ether according to 1.

(In general formula (3), F is a group selected from a hydrogen group and a cholesteryloxycarbonyl group, G is a divalent saturated hydrocarbon group having 1 to 15 carbon atoms, H is a carbonyl group, a methylene group, and oxycarbonylethylenecarbonyl group. Represents a group selected from groups.) A cholesteric liquid crystal additive comprising the sugar alcohol ester or ether according to claim 1 . The cholesteric liquid crystal composition characterized by comprising a cholesteric liquid crystal additive according to claim 3 in the cholesteric liquid crystal. A recording medium comprising the cholesteric liquid crystal composition according to claim 4. 6. A display element, wherein the cholesteric liquid crystal composition according to claim 4 or the recording medium according to claim 5 is sandwiched between at least one transparent substrate. The wavelength of reflected light is 700 nm or more before the display element is irradiated with ultraviolet rays, and the reflected color is changed from red to blue by the irradiation of ultraviolet rays, and the changed reflected color is fixed to a glass state. The display element according to claim 6 , wherein the display element maintains a state in which the reflected color does not change even when heated at 70 ° C. for 30 minutes.

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