JP6398163B2 - Liquid crystal element, screen and display using the liquid crystal element, and liquid crystal composition - Google Patents

Description

  The present invention relates to a liquid crystal element, a screen and a display using the liquid crystal element, a liquid crystal composition, and a method for manufacturing the liquid crystal element. More specifically, a liquid crystal that is effective for a liquid crystal element usable in a so-called reverse mode that does not use a polarizing plate and is in a transmission state or selective reflection state with respect to visible light when no voltage is applied, and is in a scattering state when voltage is applied. The present invention relates to a composition, a liquid crystal element, a display and a screen using the liquid crystal element, and a method for manufacturing the liquid crystal element.

Conventionally, liquid crystal elements in which liquid crystal alignment is fixed by combining liquid crystal and a transparent polymer resin are called polymer-stabilized liquid crystals (PSLC) and exhibit excellent optical characteristics and response characteristics. It is attracting attention and is used for displays and the like. As this liquid crystal element, a liquid crystal composition and an element suitable for an AM (active matrix) element are disclosed. (Patent Document 1).
Among liquid crystal elements, a transmission-scattering type liquid crystal element that uses a difference in refractive index between a polymer and a liquid crystal or a liquid crystal domain by combining a liquid crystal and a transparent polymer resin does not require a polarizing plate. It is attracting attention because of its high visible light utilization efficiency. As transmission-scattering electro-optical elements, polymer dispersed liquid crystals (PDLC) are widely known in addition to PSLC. The former has a structure in which a small amount of polymer is connected as a network network in a continuously spreading liquid crystal phase, and the latter has a structure in which liquid crystal phase droplets are dispersed in a polymer film (Non-patent Document 1). .
These liquid crystal elements have been put into practical use as light control shutters for the purpose of protecting design and privacy in windows, doors, partitions, etc. of trains, cars and other vehicles, business buildings, hospitals, etc. . It is also used as a display device for displaying characters and figures.
In such a device, since the use time in the transparent state is generally overwhelmingly long, from the viewpoint of power saving, it is transparent when no voltage is applied, and operates in a reverse mode electro-optic effect that operates in a scattering state when a voltage is applied. It is desirable to have

  In order to realize this reverse mode transmission-scattering electro-optical element, generally, a photocurable liquid crystal composition is photocured while maintaining a transparent state such as homogeneous, planar, homeotropic, etc. Methods for forming resin composites are known. As such liquid crystal elements, PSCT (Polymer Stabilized Cholesteric Texture) using visible light transmission scattering due to phase change of chiral nematic liquid crystal with positive dielectric anisotropy as PSLC and negative dielectric anisotropy as PDLC. A method of using liquid crystal is known. However, the latter has problems such that the temperature dependency of the visible light transmittance is large, the viewing angle dependency is large, or the liquid crystal is expensive. On the other hand, the former is promising because it has the advantages that the temperature dependence of the visible light transmittance is small, the viewing angle dependence of the visible light transmittance is small, and the response speed of the element is fast.

As a method for producing a PSCT type liquid crystal device, a liquid crystal composition in which a trace amount of a polymerizable monomer and a polymerization initiator are mixed in a chiral nematic liquid crystal having positive dielectric anisotropy is obtained by photopolymerization to form a chiral nematic liquid crystal phase. Patent Document 2 discloses a method for forming a network polymer network by phase separation into a polymer resin phase.
The characteristics of the polymerizable monomer used in the PSCT method are generally known to have 1) crosslinkability, 2) linear type, and 3) a rigid core (Non-Patent Document 2). Patent Document 3 includes a curable compound having a chroman structure as a partial structure, and a liquid crystal element having good optical characteristics, which is made of a resin derived from the curable compound and chiral nematic liquid crystal. .
Patent Document 4 describes a composite containing a cured product of a curable compound having a 4,4′-biphenylene skeleton with improved curing speed and a liquid crystal. Patent Document 5 describes that a polymer of 4,4′-bisacryloyloxybiphenyl compound is used as a transparent solid material of the light control layer, and the device can be formed in a short time by irradiation with high-intensity ultraviolet rays. Manufactured.

International Publication WO2011 / 092973 Japanese Patent Publication No. 6-507505 JP-A-9-90328 JP 2000-119656 A JP-A-5-224187

Dierking, I. Adv Mater 2000, 12, 167 Yuhai Yin, Journal of Applied Polymer Science, Vol. 111, 1353-1357 (2009)

In order to realize a good contrast in a reverse mode PSCT liquid crystal element, it is necessary to stably maintain the planar structure of the liquid crystal in the composite of the chiral nematic liquid crystal and the polymer resin when no voltage is applied. Conventionally, it is known that the characteristics depend greatly on the interfacial interaction between the chiral nematic liquid crystal and the polymer resin and the structure form of the polymer. The structural form cannot be predicted.
In recent research, in order to improve the compatibility between the host liquid crystal and the polymer precursor in order to obtain high contrast, a method using a liquid crystalline monomer as in Patent Document 4 is known. However, even when such a monomer is used, when trying to cure at high speed with strong light, the liquid crystal structure is disturbed due to intense phase separation or temperature rise caused by the light source or reaction heat, and the transmittance in the transparent state is reduced. Occurs. Furthermore, Patent Document 3 requires a long time of several hours to cure the composition, and Patent Document 4 has improved the curing speed, but it still takes several tens of minutes to cure the composition. In terms of manufacturability, it is not satisfactory. On the other hand, Patent Document 5 manufactures an element in a short time by high-illuminance ultraviolet irradiation, but it is not yet satisfactory in terms of optical characteristics and driving characteristics.
Patent Document 1 discloses an AM device having a high contrast and manufactured using a liquid crystal composition having a negatively large dielectric anisotropy in which a bis (meth) acryloyloxynaphthalene compound is dissolved. The composition is applied to a method that requires a polarizing plate for display, and the liquid crystal element has a low visible light transmittance and low light use efficiency.

  The present invention has been made in view of the above problems, and can be used for a liquid crystal element of the PSCT method, can be manufactured in a short time, has a high contrast, and is colorless and highly transparent. An object of the present invention is to provide a display, a screen, a liquid crystal composition suitable for the liquid crystal element, and a production method.

As a result of intensive studies to solve the above problems, the present inventors can drive in the reverse mode by using a liquid crystal element including a chiral nematic liquid crystal phase and a specific polymer, and exhibit high contrast and high-speed response. I found out. In addition, in a liquid crystal composition containing a chiral nematic liquid crystal and a polymerizable monomer, the liquid crystal composition containing a polymerizable monomer that is a specific polymer precursor has a high illuminance even though the polymerizable monomer is non-liquid crystalline. Thus, the present inventors have found that a reverse mode liquid crystal element exhibiting a high contrast can be realized even when the composition is cured at high speed in a short time without disturbing the planar structure of the liquid crystal.

That is, the gist of the present invention is as follows.
(1) Liquid crystal dimming comprising at least one transparent substrate, having a pair of substrates with electrodes arranged opposite to each other, and a composite containing a chiral nematic liquid crystal phase and a polymer resin phase between the substrates A liquid crystal element having a layer, wherein the polymer resin phase contains a polymer compound having a polymer represented by the following general formula (1), and the chiral nematic liquid crystal phase has a positive dielectric anisotropy. A liquid crystal element.

[In general formula (1),
X ¹⁰⁰ represents good alkylene group which may have a substituent, which may have a may have a substituent aromatic hydrocarbon group or a substituted aromatic heterocyclic group,
R ¹⁰⁰ represents a hydrogen atom or an alkyl group which may have a substituent,
y represents an integer of 1 or more, and two or more X ¹⁰⁰ present in one molecule of the polymer represented by the general formula (1) may be the same or different,
z represents an integer of 1 to 3, and when z is 2 or more, two or more X ¹⁰¹ present in one molecule of the polymer represented by the general formula (1) may be the same or different. ¹⁰¹ represents a group represented by the following general formula (2),

In general formula (2), ^X102 represents a direct bond or one linking group selected from the following group,

X ¹⁰³ represents a direct bond or one linking group selected from the following group:

R ¹⁰¹ represents a hydrogen atom, a halogen atom, a hydroxyl group, a linear or branched alkyl group having 1 to 7 carbon atoms, a linear or branched alkoxy group having 1 to 7 carbon atoms, or a cyano group. Represent,
z ′ represents an integer of 1 to 3, and when z ′ is 2 or more, two or more of —X ¹⁰² —X ¹⁰³ — present in one molecule of the polymer represented by the general formula (2) are the same. May be different. (2) The liquid crystal element according to (1), wherein the chiral nematic liquid crystal contains a compound having a cyano group.
(3) The liquid crystal element according to (1) or (2), wherein a chiral pitch length p of the chiral nematic liquid crystal is 0.3 μm or more and 3 μm or less.
(4) In any one of the above (1) to (3), there is a region of DC voltage and / or AC voltage in which the visible light transmittance when a voltage is applied is lower than the visible light transmittance when no voltage is applied. The liquid crystal element as described. (5) The distance d between the substrates with electrodes is 100 μm ≧ d ≧ 2 μm, and the relationship between the chiral pitch length p and d of the chiral nematic liquid crystal is d / p ≧ 1, (1) to (4 The liquid crystal element according to any one of 1).
(6) The haze when applying at least one of a DC voltage and an AC voltage is 70% or more, and the haze when no voltage is applied is 15% or less. Liquid crystal element.
(7) In a temperature range of −10 ° C. or higher, the visible light transmittance at the time of no application of at least one of the DC voltage and AC voltage of the liquid crystal element is reduced by 100%, and the application of at least one of DC voltage and AC voltage is reduced. When the visible light transmittance when normalized to 0% is normalized to 0%, the time from when at least one of the DC voltage and the AC voltage is applied until the visible light transmittance becomes 10%, and the DC voltage And the liquid crystal element according to any one of the above (1) to (6), wherein the time from when at least one of the AC voltages is not applied until the visible light transmittance reaches 90% is 8 msec or less, respectively. .
(8) The liquid crystal element according to any one of (1) to (7), wherein the yellowing degree of the liquid crystal element is 4 or less.
(9) A screen having the liquid crystal element according to any one of (1) to (8).
(10) A display having the liquid crystal element according to any one of (1) to ( 8 ).
(11) A liquid crystal composition containing a chiral nematic liquid crystal having a positive dielectric anisotropy and a polymerizable monomer represented by the following general formula (3).

[In general formula (3),
X ¹ represents a good alkylene group which may have a substituent, which may have a may have a substituent aromatic hydrocarbon group or a substituted aromatic heterocyclic group,
R ¹ represents a hydrogen atom or an alkyl group which may have a substituent,
n represents an integer of 1 or more, and X ¹ present in two or more polymerizable monomers represented by the general formula (3) may be the same or different,
m represents an integer of 1 to 3, and when m is 2 or more, two or more X ² present in one molecule of the polymerizable monomer represented by the general formula (3) may be the same or different. , X ² represents a group represented by the following general formula (4),

In general formula (4), X ¹⁰ represents a direct bond or one linking group selected from the following group,

X ¹¹ represents a direct bond or one linking group selected from the following group:

R ¹⁰ represents a hydrogen atom, a halogen atom, a hydroxyl group, a linear or branched alkyl group having 1 to 7 carbon atoms, a linear or branched alkoxy group having 1 to 7 carbon atoms, or a cyano group. Represent,
w represents an integer of 1 to 3, and when w is 2 or more, two or more -X ¹⁰ -X ^11- present in one molecule of the polymerizable monomer represented by the general formula (4) are the same. May be different. (12) The liquid crystal composition as described in (11) above, wherein the chiral nematic liquid crystal contains a compound having a cyano group.
(13) The liquid crystal composition as described in (11) or (12) above, wherein a chiral pitch length p of the chiral nematic liquid crystal is 0.3 μm or more and 3 μm or less.
(14) The liquid crystal-isotropic phase transition temperature is 40 ° C. or higher, (11) to (1)
The liquid crystal composition according to any one of 3).

  The liquid crystal element of the present invention does not deteriorate in driving and can be driven in a reverse mode, has high visible light utilization efficiency, has low temperature dependency and viewing angle dependency, and can provide high contrast and high-speed response. is there. Furthermore, even when the liquid crystal composition is produced at a high speed in a short period of time when producing a liquid crystal element, the planar structure of the liquid crystal is not disturbed and a high contrast and a high speed response are possible. The liquid crystal element of the present invention and the liquid crystal element obtained by using the liquid crystal composition are useful for use in screens and displays because of these characteristics. For example, it can be used as a display or screen for announcement boards, computer terminals, projections, etc. by switching the display electrically with high-speed response, such as screens for blocking visual fields such as building windows, partitions and show windows. can do.

  The description of the constituent requirements described below is an example (representative example) of an embodiment of the present invention, and is not specified by these contents.

  The liquid crystal element of the present invention is a composite comprising at least one transparent substrate, having a pair of substrates with electrodes arranged opposite to each other, and including a chiral nematic liquid crystal phase and a polymer resin phase between the substrates. A liquid crystal device having a liquid crystal light control layer containing the polymer resin phase, wherein the polymer resin phase contains a polymer compound having a polymer represented by the following general formula (1), and having a dielectric constant different from that of the chiral nematic liquid crystal phase. It is characterized by positiveness.

[In general formula (1),
X ¹⁰⁰ represents an alkyl group that may have a substituent, an aromatic hydrocarbon group that may have a substituent, or an aromatic heterocyclic group that may have a substituent,
R ¹⁰⁰ represents a hydrogen atom or an alkyl group which may have a substituent,
y represents an integer of 1 or more, and two or more X ¹⁰⁰ present in one molecule of the polymer represented by the general formula (1) may be the same or different,
z represents an integer of 1 to 3, and when z is 2 or more, two or more X ¹⁰¹ present in one molecule of the polymer represented by the general formula (1) may be the same or different. ¹⁰¹ represents a group represented by the following general formula (2),

In general formula (2), ^X102 represents a direct bond or one linking group selected from the following group,

X ¹⁰³ represents a direct bond or one linking group selected from the following group:

R ¹⁰¹ represents a hydrogen atom, a halogen atom, a hydroxyl group, a linear or branched alkyl group having 1 to 7 carbon atoms, a linear or branched alkoxy group having 1 to 7 carbon atoms, or a cyano group. Represent,
w represents an integer of 1 to 3, and when w is 2 or more, two or more -X ¹⁰² -X ^103- present in one molecule of the polymer represented by the general formula (2) may be the same or different. It may be. )

Although the reason why the liquid crystal element of the present invention realizes a reverse mode liquid crystal element exhibiting high contrast is not necessarily clear, the polymer resin phase of the present invention has two polymer main chains in the form of a ladder with a naphthalene ring. An anchoring effect that is thought to be derived from the naphthalene ring (liquid crystal components are aligned in a specific direction by interfacial interaction) while having sufficient mechanical strength and thus having a very rigid structure. It is considered that the response time from voltage application to no voltage application is sufficiently fast.
Moreover, it is thought that the said effect | action is shown because the number of the acyl groups containing the unsaturated bond which the naphthalene ring of this polymer has is two. When one acyl group is bonded to the naphthalene ring, sufficient mechanical strength of the polymer resin phase cannot be obtained, and the repeated durability of the liquid crystal element is greatly deteriorated, so that high contrast cannot be obtained. On the other hand, when there are three acyl groups, the steric hindrance between the polymerizable monomers is large, the polymerization main chain is interrupted before the polymer network structure is sufficiently developed, and high contrast cannot be obtained.

X ¹⁰⁰ represents an alkyl group which may have a substituent, an aromatic hydrocarbon group which may have a substituent, or an aromatic heterocyclic group which may have a substituent.
The alkyl group which may have a substituent X ^100, methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl and the like A linear alkyl group: a branched alkyl group such as isopropyl group, isobutyl group, sec-butyl group, tert-butyl group, isooctyl group, isononyl group; cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cyclopropylmethyl And cyclic alkyl groups such as a group, a cyclohexylmethyl group, and a 4-butylmethylcyclohexyl group. Among these, the number of carbon atoms is preferably 1 or more, and the number of carbon atoms is preferably 20 or less, and the number of carbon atoms is preferably 16 or less from the viewpoint of compatibility with liquid crystals and ease of polymerization. .
As the substituent which may be possessed by the alkyl group of X ^100, a halogen atom, an alkoxy group having 1 to 20 carbon atoms, and the like alkoxycarbonyl group or a cyano group having 2 to 20 carbon atoms.

The aromatic hydrocarbon group which may have a substituent X ^100, a single-ring fused ring or this becomes engaged two to four condensation, a one except for obtained based on hydrogen atom, Specific examples include groups such as a benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, perylene ring, tetracene ring, pyrene ring, benzpyrene ring, chrysene ring, triphenylene ring, acenaphthene ring, fluoranthene ring, and fluorene ring. Among these, the number of carbon atoms is preferably 1 or more, and the number of carbon atoms is preferably 18 or less, and more preferably 14 or less from the viewpoint of compatibility with liquid crystal and improvement in contrast of the liquid crystal element.

The aromatic heterocyclic group which may have a substituent X ^100, monocyclic or, or from condensed ring which is engaged with two to four condensation, the hydrogen atom located at one except for the resulting group Specific examples include furan ring, benzofuran ring, thiophene ring, benzothiophene ring, pyrrole ring, pyrazole ring, imidazole ring, oxadiazole ring, indole ring, carbazole ring, pyrroloimidazole ring, pyrrolopyrazole ring, pyrrolopyrrole ring , Thienopyrrole ring, thienothiophene ring, furopyrrole ring, furofuran ring, thienofuran ring, benzisoxazole ring, benzisothiazole ring, benzimidazole ring, pyridine ring, pyrazine ring, pyridazine ring, pyrimidine ring, triazine ring, quinoline ring, isoquinoline Ring, sinoline ring, quinoxaline ring, phenant Examples include lysine ring, benzimidazole ring, perimidine ring, quinazoline ring, quinazolinone ring, and azulene ring. Among these, the number of carbon atoms is preferably 18 or less, and more preferably 14 or less from the viewpoint of compatibility with the liquid crystal and improvement of contrast of the liquid crystal element.

The aromatic hydrocarbon group and the substituent that may be possessed by the aromatic heterocyclic group X ^100, is not particularly limited as long as it does not impair the effects of the present invention, a halogen atom, a carbon number 1 to Examples include 20 alkyl groups, alkoxy groups having 1 to 20 carbon atoms, aromatic hydrocarbon groups, and aromatic heterocyclic groups.

Among these, X ¹⁰⁰ is particularly preferably a linear alkyl group from the viewpoint of compatibility with liquid crystal and improvement of contrast of the liquid crystal element.

R ¹⁰⁰ represents a hydrogen atom or an alkyl group which may have a substituent.
The alkyl group which may have a substituent of R ¹⁰⁰ is specifically synonymous with the alkyl group mentioned for X ¹ , and the substituent which may have is also synonymous.
Among these, the number of carbon atoms is preferably 1 or more, the number of carbon atoms is preferably 10 or less, the number of carbon atoms is more preferably 5 or less, and the number of carbon atoms is 3 or less. From the viewpoints of the compatibility of the liquid crystal and the improvement in contrast of the liquid crystal element.

y represents an integer of 1 or more, and two or more X ¹⁰⁰ present in one molecule of the polymer represented by the general formula (1) may be the same or different. y is preferably 1 or more, preferably 10 or less, more preferably 5 or less, and further preferably 3 or less from the viewpoint of compatibility with liquid crystal and improvement of contrast of the liquid crystal element. It is particularly preferred that

Substituted position of the side chain of a naphthalene ring including R ¹⁰⁰ is not particularly limited, if the rod-like structure comprising a naphthalene ring, the interfacial interactions between the chiral nematic liquid crystal phase, the contrast of the liquid crystal element in some cases improved preferable. Among them, the 4th, 5th and 6th positions with respect to the 1st position, the 3rd and 6th positions with respect to the 2nd position, the 7th position with respect to the 3rd position, and the 4th and 5th positions with respect to the 8th position are particularly preferable.

z represents an integer of 1 to 3, and when z is 2 or more, X ¹⁰¹ present in 2 or more in one molecule of the polymer represented by the general formula (1) may be the same or different.
If z is too large, the interfacial interaction between the naphthalene ring and the liquid crystal molecules may be sterically impaired. Therefore, it is preferably 2 or less, and more preferably 1.

X ¹⁰¹ represents a group represented by the following general formula (2).

In general formula (2), ^X102 represents a direct bond or one linking group selected from the following group,

X ¹⁰³ represents a direct bond or one linking group selected from the following group:

R ¹⁰¹ represents a hydrogen atom, a halogen atom, a hydroxyl group, a linear or branched alkyl group having 1 to 7 carbon atoms, a linear or branched alkoxy group having 1 to 7 carbon atoms, or a cyano group. Represent,
z 'represents an integer of 1 to 3, and when w is 2 or more, -X ¹⁰² -X ^103- present in 2 or more in one polymer molecule represented by the general formula (1) may be the same May be different. )

When the naphthalene ring in the polymer represented by the general formula (1) has a substituent represented by the general formula (2), the liquid crystallinity of the polymer resin phase may be controlled. For example, in order to improve liquid crystallinity, R ^{101 in the} general formula (2) is a linear or branched alkyl group having 3 to 7 carbon atoms, or a linear alkoxy group having 3 to 7 carbon atoms. Preferably there is.
The substitution position of the general formula (2) is not particularly limited, but more preferably the opposite positions (4th and 5th positions relative to the 1st position, 6th position relative to the 2nd position, 7th position relative to the 3rd position, 4th position and 5th position relative to the 8th position) When a substituent represented by the above general formula (2) is attached to each of the above and the side chain in the above general formula (1) has a rod-like structure containing a naphthalene ring, the compatibility with chiral nematic liquid crystal is improved, and the liquid crystal element Contrast may be improved.
If z ′ is too large, the compatibility of the general formula (1) with respect to the chiral nematic liquid crystal phase may be lowered. Therefore, it is preferably 2 or less, and more preferably 1.

Among the above-mentioned ^X102 , it is a direct bond or one linking group selected from the following group, so that the chiral nematic liquid crystal phase and the polymer resin phase do not absorb visible light and have high transparency. A liquid crystal element can be obtained, which is preferable.

Among X ¹⁰³ described above, a direct bond or one linking group selected from the following group is preferable because durability of the liquid crystal element may be increased, and a direct bond is more preferable.

z ′ represents an integer of 1 to 3, and when w is 2 or more, the groups represented by the general formula (2) present in one molecule of the polymer represented by the general formula (1) are the same. Or different.
If z ′ is 2 or less, the chiral nematic liquid crystal phase and the polymer resin phase do not absorb visible light, and a highly transparent liquid crystal element may be obtained, more preferably 1. .

R ¹⁰¹ represents a hydrogen atom, a halogen atom, a hydroxyl group, a linear or branched alkyl group having 1 to 7 carbon atoms, a linear or branched alkoxy group having 1 to 7 carbon atoms, or a cyano group. Represent.
Examples of the linear or branched alkyl group having 1 to 7 carbon atoms for R ¹⁰ include methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group, n-hexyl group, n- A heptyl group, and examples of the branched alkyl group having 1 to 7 carbon atoms include isopropyl group, isobutyl group, t-butyl group, 2-methylpentyl group, 3-methylpentyl group, 4-methylpentyl group, Examples include 2-ethylpentyl group, 3-ethylpentyl group, 4-ethylpentyl group and the like.
Examples of the linear alkoxy group having 1 to 7 carbon atoms include a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group, an n-pentoxy group, an n-hexoxy group, and an n-heptoxy group. Examples of the branched alkoxy group of 1 to 7 include isopropoxy group, isobutoxy group, t-butoxy group, 2-methylpentoxy group, 3-methylpentoxy group, 4-methylpentoxy group, 2-ethyl. Examples thereof include a pentoxy group, a 3-ethylpentoxy group, and a 4-ethylpentoxy group.
Among these, the durability of the polymer resin phase may be increased by being a hydrogen atom, a linear alkyl group having 1 to 7 carbon atoms, or a linear alkoxy group having 1 to 7 carbon atoms. Therefore, a hydrogen atom, a methyl group, and a methoxy group are more preferable.

Specific examples of the polymer represented by the general formula (1) are illustrated below. This invention is not limited to these unless it exceeds the gist.

The chiral nematic liquid crystal phase of the present invention may contain a chiral nematic liquid crystal having a positive dielectric anisotropy and a polymerizable monomer represented by the general formula (3) described later. By the presence of polymerizable monomers. In some cases, the drive characteristics of the liquid crystal element can be improved and stabilized.
In the liquid crystal device of the present invention, a polymer resin phase can be obtained by subjecting a liquid crystal composition containing a chiral nematic liquid crystal, a polymerizable monomer, and a polymerization initiator to polymerization-induced phase separation in a cholesteric phase in the production process. This polymerization initiator is useful in terms of increasing the polymerization rate and improving the curing rate during the production of a liquid crystal device. On the other hand, decomposition products generated in the polymerization process remain in the chiral nematic liquid crystal phase as ionic low molecules. The liquid crystal device drive is degraded by degrading the compound in the liquid crystal device by degrading the drive of the liquid crystal device or generating radical species over time by leaving unreacted substances in the chiral nematic liquid crystal phase in the liquid crystal device. May deteriorate.
The present invention uses a polymerizable monomer that is highly photoreactive and that can be sufficiently polymerized even with a small amount of a polymerization initiator, and while consuming all of the polymerization initiator in the polymerization-induced phase separation process, By manufacturing so as to remain in the chiral nematic liquid crystal phase, there is a case where a liquid crystal element that satisfies all of the manufacturing of a liquid crystal element in a short time, high contrast, and high-speed response may be obtained.

In the present invention, the amount of the polymerizable monomer represented by the general formula (3) contained in the chiral nematic liquid crystal phase is not particularly limited as long as the effects of the present invention are not impaired, but in 1 g of the chiral nematic liquid crystal phase, It is preferable to contain 5 μg or more of the polymerizable monomer represented by the general formula (3), and it is preferable to contain 50 μg or more. Moreover, it is preferable to contain 500 microgram or less, and it is more preferable to contain 300 microgram or less.
When the amount of the polymerizable monomer represented by the general formula (3) contained in the chiral nematic liquid crystal phase is too small, it means that the addition amount of the polymerization initiator in the liquid crystal composition before polymerization is too large, as described above. In some cases, the driving of the liquid crystal element may be deteriorated. On the other hand, if the amount of the polymerizable monomer is too large, liquid crystal element characteristics such as drive voltage may fluctuate due to the polymerization reaction over time.
The chiral nematic liquid crystal phase in the present invention can be easily separated and recovered by a method such as washing away from the liquid crystal element using an organic solvent. The polymerizable monomer represented by the general formula (3) in the chiral nematic liquid crystal phase can be easily quantified by using liquid chromatography mass spectrometry.

<Polymer structure (molecular weight)>
In the present invention, a structure (polymer network structure) in which a trace amount of polymer is linked as a network network develops in a continuously spread chiral nematic liquid crystal phase. It has the shape of a spherical particle.

The molecular weight of the polymer of the structural unit is not particularly limited as long as the effects of the present invention are not impaired, but the molecular weight is preferably 1000 or more, more preferably 2000 or more. Further, it is preferably 10000000 or less, more preferably 5000000 or less.
If the molecular weight of the polymer is less than this, the polymer resin phase becomes mechanically fragile, and the polymer network structure is not sufficiently developed, so that the repeated durability deteriorates. As a result, the liquid crystal molecules cannot receive sufficient interface interaction, and the contrast and response speed of the liquid crystal element may be deteriorated. On the other hand, when the molecular weight of the polymer is higher than this, the chiral nematic liquid crystal phase is spatially divided, the planar structure is not stabilized, and the transparency of the liquid crystal element when no voltage is applied may be deteriorated. . As a method for analyzing the molecular weight of the present polymer, it can be easily quantified by using gel permeation chromatography (GPC), but is not particularly limited and can be analyzed by methods well known to those skilled in the art.

<Polymer structure (fiber or particle diameter)>
In the present invention, a structure (polymer network structure) in which a minute amount of polymer is connected as a network network develops in a continuously spreading chiral nematic liquid crystal phase. Having the shape of particles.
The diameter of the fibers of the structural unit or the diameter of the spherical particles is not particularly limited as long as the effects of the present invention are not impaired, but the diameter is preferably 10 nm or more, more preferably 30 nm or more. Moreover, it is preferable that it is 5000 nm or less, More preferably, it is 1000 nm or less.
If the diameter of the fiber or particle is less than this, the polymer resin phase becomes mechanically brittle, and the polymer network structure does not develop sufficiently, so that the repeated durability deteriorates. As a result, the liquid crystal molecules cannot receive sufficient interface interaction, and the contrast and response speed of the liquid crystal element may be deteriorated. Furthermore, the handling characteristics of the element may be deteriorated. On the other hand, when the diameter of the fiber or particle is larger than this, the chiral nematic liquid crystal phase is spatially divided, the planar structure is not stabilized, and the transparency of the liquid crystal element when no voltage is applied deteriorates There is. In addition, the deterioration of the insulating properties of the element may cause the liquid crystal element characteristics such as the driving voltage to fluctuate. The diameter of the fiber or particle forming the structural unit of the present polymer network can be easily measured by using an electron microscope, but is not particularly limited and can be analyzed by a method well known to those skilled in the art. .

  The liquid crystal light control layer of the present invention includes a composite containing a chiral nematic liquid crystal phase and a polymer resin phase, and is preferably a polymer stabilized liquid crystal (PSLC). As a feature of PSLC, the polymer resin phase has a network polymer network structure, and the ratio of the polymer resin phase to the chiral nematic liquid crystal phase is 10% by mass or less. By being a PSLC, it is possible to adopt a structure in which chiral nematic liquid crystal phases are continuously connected in the liquid crystal light control layer, and the transparency when no voltage is applied to the liquid crystal element and the scattering intensity when a voltage is applied are sufficient. Can be increased.

<Other repeat units>
The liquid crystal element of the present invention may have other polymers in addition to the polymer represented by the above formula (1) as long as the effects of the present invention are not impaired.
The ratio of the polymer represented by the general formula (1) of the liquid crystal element of the present invention and the other repeating polymer is not particularly limited as long as the effect of the present invention is not impaired, but is represented by the general formula (1). The polymer is preferably 30% by mass or more, more preferably 50% by mass or more, and most preferably 80% by mass or more.
If the proportion of the polymer represented by the above formula (1) is too small, one or more of liquid crystal device production in a short time, high contrast, short response time, or a plurality may not be sufficient. Moreover, the upper limit of the polymer represented by the formula (1) is 100% by mass.
Moreover, when the polymer resin which the polymer resin phase of this invention has is a copolymer, any of an alternating copolymer, a block copolymer, a random copolymer, and a graft copolymer may be sufficient.

  The liquid crystal composition of the present invention comprises a chiral nematic liquid crystal having a positive dielectric anisotropy and a polymerizable monomer represented by the following general formula (3).

[In general formula (3),
X ¹ represents an alkyl group that may have a substituent, an aromatic hydrocarbon group that may have a substituent, or an aromatic heterocyclic group that may have a substituent,
R ¹ represents a hydrogen atom or an alkyl group which may have a substituent,
n represents an integer of 1 or more, and two or more X ¹ present in one molecule of the polymerizable monomer represented by the general formula (3) may be the same or different,
m represents an integer of 1 to 3, and when m is 2 or more, two or more X ² present in one molecule of the polymerizable monomer represented by the general formula (3) may be the same or different. , X ² represents a group represented by the following general formula (4),

In the general formula (4), X ¹⁰ represents a direct bond or one linking group selected from the following group,

X ¹¹ represents a direct bond or one linking group selected from the following group:

R ¹⁰ represents a hydrogen atom, a halogen atom, a hydroxyl group, a linear or branched alkyl group having 1 to 7 carbon atoms, a linear or branched alkoxy group having 1 to 7 carbon atoms, or a cyano group. W represents an integer of 1 to 3, and when w is 2 or more, -X ¹⁰ -X ^11- present in two or more polymerizable monomers represented by the general formula (3) are the same. It may or may not be. )

Although the liquid crystal composition of the present invention is cured at a high speed with a strong light intensity, the planar structure of the liquid crystal is not disturbed, and as a result, the factor for realizing a reverse mode liquid crystal element exhibiting high contrast is not always clear. However, the polymer precursor (polymerizable monomer) has a structure suitable for memorizing the planar structure with respect to the chiral nematic liquid crystal, and the naphthalene ring in the polymer resin is a useful interface for the chiral nematic liquid crystal. This is considered to be an interaction.
Moreover, it is thought that said effect | action is shown because the number of the acyl groups containing the unsaturated bond which the naphthalene ring of this polymerizable monomer has is two. When one acyl group is bonded to the naphthalene ring, sufficient mechanical strength of the polymer resin phase cannot be obtained, and the repeated durability of the liquid crystal element is greatly deteriorated, so that high contrast cannot be obtained. On the other hand, when there are three acyl groups, the steric hindrance between the polymerizable monomers is large, the polymerization main chain is interrupted before the polymer network structure is sufficiently developed, and high contrast cannot be obtained.

X ¹ represents an alkyl group which may have a substituent, an aromatic hydrocarbon group which may have a substituent, or an aromatic heterocyclic group which may have a substituent.
Examples of the alkyl group which may have a substituent for X ¹ include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, and a dodecyl group. A linear alkyl group: a branched alkyl group such as isopropyl group, isobutyl group, sec-butyl group, tert-butyl group, isooctyl group, isononyl group; cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cyclopropylmethyl And cyclic alkyl groups such as a group, a cyclohexylmethyl group, and a 4-butylmethylcyclohexyl group. Among these, the number of carbon atoms is preferably 1 or more, and the number of carbon atoms is preferably 20 or less, and the number of carbon atoms is preferably 16 or less from the viewpoint of compatibility with liquid crystals and ease of polymerization. .
In addition, examples of the substituent that the alkyl group of X ¹ may have include a halogen atom, an alkoxy group having 1 to 20 carbon atoms, an alkoxycarbonyl group having 2 to 20 carbon atoms, and a cyano group.

The aromatic hydrocarbon group which may have a substituent for X ^{1 is} a group obtained by removing one hydrogen atom from a single ring or a condensed ring formed by condensation of 2 to 4 thereof, Specific examples include groups such as a benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, perylene ring, tetracene ring, pyrene ring, benzpyrene ring, chrysene ring, triphenylene ring, acenaphthene ring, fluoranthene ring, and fluorene ring. Among these, the number of carbon atoms is preferably 1 or more, and the number of carbon atoms is preferably 18 or less, and more preferably 14 or less from the viewpoint of compatibility with the liquid crystal and ease of polymerization.

The aromatic heterocyclic group which may have a substituent for X ^{1 is} a group obtained by removing one hydrogen atom from a monocyclic ring or a condensed ring formed by condensing 2 to 4 thereof. Specific examples include furan ring, benzofuran ring, thiophene ring, benzothiophene ring, pyrrole ring, pyrazole ring, imidazole ring, oxadiazole ring, indole ring, carbazole ring, pyrroloimidazole ring, pyrrolopyrazole ring, pyrrolopyrrole ring , Thienopyrrole ring, thienothiophene ring, furopyrrole ring, furofuran ring, thienofuran ring, benzisoxazole ring, benzisothiazole ring, benzimidazole ring, pyridine ring, pyrazine ring, pyridazine ring, pyrimidine ring, triazine ring, quinoline ring, isoquinoline Ring, sinoline ring, quinoxaline ring, phenanthridi Groups such as thiophene ring, benzimidazole ring, perimidine ring, quinazoline ring, quinazolinone ring, and azulene ring. Among these, the number of carbon atoms is preferably 1 or more, and the number of carbon atoms is preferably 18 or less, and more preferably 14 or less from the viewpoint of compatibility with the liquid crystal and ease of polymerization.

The substituent that the aromatic hydrocarbon group and aromatic heterocyclic group of X ¹ may have is not particularly limited as long as the effects of the present invention are not impaired, but a halogen atom and a carbon number of 1 to 1 Examples include 20 alkyl groups, alkoxy groups having 1 to 20 carbon atoms, aromatic hydrocarbon groups, and aromatic heterocyclic groups.

Among these, X ¹ is particularly preferably a linear alkyl group from the viewpoint of ease of polymerization.

R ¹ represents a hydrogen atom or an alkyl group which may have a substituent.
The alkyl group which may have a substituent for R ¹ is specifically synonymous with the alkyl group mentioned for X ¹ , and the substituent which may have is also synonymous.
Among these, the number of carbon atoms is preferably 1 or more, the number of carbon atoms is preferably 10 or less, the number of carbon atoms is more preferably 5 or less, and the number of carbon atoms is 3 or less. From the viewpoint of compatibility and ease of polymerization.

n represents an integer of 1 or more, and two or more X ¹ present in one molecule of the polymerizable monomer represented by the general formula (3) may be the same or different. From the viewpoint of compatibility with liquid crystal and ease of polymerization, n is preferably 1 or more, more preferably 10 or less, still more preferably 5 or less, and further preferably 3 or less. It is particularly preferred that

The substitution position of the side chain of the naphthalene ring containing R ¹ is not particularly limited, but if a rod-like structure containing a naphthalene ring is used, the contrast of the liquid crystal element may be improved due to the interface interaction with the chiral nematic liquid crystal phase. preferable. Among them, the 4th, 5th and 6th positions with respect to the 1st position, the 3rd and 6th positions with respect to the 2nd position, the 7th position with respect to the 3rd position, and the 4th and 5th positions with respect to the 8th position are particularly preferable.

m represents an integer of 1 to 3, and when m is 2 or more, two or more X ² present in one molecule of the polymerizable monomer represented by the general formula (3) may be the same or different. .
If m is too large, the interfacial interaction between the naphthalene ring and the liquid crystal molecules may be sterically impaired. Therefore, it is preferably 2 or less, and more preferably 1.

X ² represents a group represented by the following general formula (4).

In the general formula (4), X ¹⁰ represents a direct bond or one linking group selected from the following group,

X ¹¹ represents a direct bond or one linking group selected from the following group:

R ¹⁰ represents a hydrogen atom, a halogen atom, a hydroxyl group, a linear or branched alkyl group having 1 to 7 carbon atoms, a linear or branched alkoxy group having 1 to 7 carbon atoms, or a cyano group. Represent,
w represents an integer of 1 to 3, and when w is 2 or more, two or more of -X ¹⁰ -X ^11- present in one molecule of the polymerizable monomer represented by the general formula (3) are the same. May be different. )

When the naphthalene ring in the polymerizable monomer represented by the general formula (3) has a substituent represented by the general formula (4), the liquid crystallinity of the polymer resin phase may be controlled. is there. For example, in order to improve liquid crystallinity, R ^{10 in the} general formula (4) is a linear or branched alkyl group having 3 to 7 carbon atoms, or a linear alkoxy group having 3 to 7 carbon atoms. Preferably there is.
The substitution position of the general formula (4) is not particularly limited, but more preferably the opposite positions (4th and 5th positions relative to the 1st position, 6th position relative to the 2nd position, 7th position relative to the 3rd position, 4th position and 5th position relative to the 8th position) When a substituent represented by the above general formula (4) is attached to each of the above, and the side chain in the above general formula (3) has a rod-like structure containing a naphthalene ring, the compatibility with chiral nematic liquid crystal is improved. Contrast may be improved.
If w is too large, the compatibility of the general formula (3) with respect to the chiral nematic liquid crystal phase may be lowered. Therefore, it is preferably 2 or less, and more preferably 1.

Among the above X ^10, a direct bond or by a single linking group selected from the following group, the chiral nematic liquid crystal phase and polymer resin phase does not absorb to visible light, highly transparent A liquid crystal element can be obtained, which is preferable.

Among X ¹¹ described above, a direct bond or one linking group selected from the following group is preferable because durability of the liquid crystal element may be increased, and a direct bond is more preferable.

w represents an integer of 1 to 3, and when w is 2 or more, the groups represented by the general formula (4) present in two or more molecules of one compound represented by the general formula (3) are the same, May be different.
If w is 2 or less, the chiral nematic liquid crystal phase and the polymer resin phase do not absorb visible light, and a highly transparent liquid crystal element may be obtained, more preferably 1.

R ¹⁰ represents a hydrogen atom, a halogen atom, a hydroxyl group, a linear or branched alkyl group having 1 to 7 carbon atoms, a linear or branched alkoxy group having 1 to 7 carbon atoms, or a cyano group. Represent.
Examples of the linear or branched alkyl group having 1 to 7 carbon atoms for R ¹⁰ include methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group, n-hexyl group, n- A heptyl group, and examples of the branched alkyl group having 1 to 7 carbon atoms include isopropyl group, isobutyl group, t-butyl group, 2-methylpentyl group, 3-methylpentyl group, 4-methylpentyl group, Examples include 2-ethylpentyl group, 3-ethylpentyl group, 4-ethylpentyl group and the like.
Examples of the linear alkoxy group having 1 to 7 carbon atoms include a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group, an n-pentoxy group, an n-hexoxy group, and an n-heptoxy group. Examples of the branched alkoxy group of 1 to 7 include isopropoxy group, isobutoxy group, t-butoxy group, 2-methylpentoxy group, 3-methylpentoxy group, 4-methylpentoxy group, 2-ethyl. Examples thereof include a pentoxy group, a 3-ethylpentoxy group, and a 4-ethylpentoxy group.
Among these, the durability of the polymer resin phase may be increased by being a hydrogen atom, a linear alkyl group having 1 to 7 carbon atoms, or a linear alkoxy group having 1 to 7 carbon atoms. Therefore, a hydrogen atom, a methyl group, and a methoxy group are more preferable.

  Specific examples of the polymerizable monomer represented by the general formula (3) are shown below. This invention is not limited to these unless it exceeds the gist.

<Other polymerizable monomers>
In addition to the polymerizable monomer represented by the above formula (3), the liquid crystal composition of the present invention may have other polymerizable monomers as long as the effects of the present invention are not impaired.
Specifically, other polymerizable monomers having one or more ethylenically unsaturated double bonds, such as (meth) acrylic or vinyl, and one ethylenically unsaturated double bond It may be copolymerized with a polymerizable monomer represented by the above formula (1) by a curing reaction.
For example, polymerizable monomers such as monofunctional (meth) acrylic monomers, bifunctional (meth) acrylic monomers, trifunctional or higher polyfunctional (meth) acrylic monomers described in Japanese Patent Application Laid-Open No. 9-90328, and (meta ) Polymerizable oligomers such as acrylic oligomers can be used.
Examples of vinyl monomers include styrene, chlorostyrene, α-methylstyrene, divinylbenzene and the like.

The ratio of the polymerizable monomer represented by the formula (3) and the other polymerizable monomer of the liquid crystal element of the present invention is not particularly limited as long as the effect of the present invention is not impaired, but the formula (3) Is preferably 30% by mass or more, more preferably 50% by mass or more, and most preferably 80% by mass or more.
If the ratio of the polymerizable monomer represented by the formula (3) is too small, there are cases where either a liquid crystal element production in a short time, a high contrast, a short response time, or a plurality are not sufficient. Moreover, the upper limit of the repeating unit represented by said Formula (1) is 100 mass%.
Further, when the polymer resin obtained using the liquid crystal composition of the present invention is a copolymer, any of an alternating copolymer, a block copolymer, a random copolymer, and a graft copolymer may be used.

<Combination ratio>
The liquid crystal composition of the present invention is designed to exhibit a cholesteric phase at room temperature (25 ° C.), and the liquid crystal-isotropic phase transition temperature (Tni) is preferably 40 ° C. or higher, more preferably 60 ° C. or higher.
When the Tni of the liquid crystal composition of the present invention is outside the above range, there is a concern that the liquid crystal structure may be destroyed due to a temperature rise derived from a light source or reaction heat during curing.
The compounding ratio of each component in the liquid crystal composition cannot be generally specified depending on the components as long as the liquid crystal composition forms a cholesteric phase, but is represented by the general formula (3) in the liquid crystal composition of the present invention. The content of the polymerizable monomer is usually 0.1% by mass or more, preferably 1% by mass or more, and is usually 10% by mass or less, preferably 7% by mass or less. Further, when the polymerizable monomer represented by the general formula (3) is used in combination with another polymerizable monomer and / or a non-polymerizable monomer, the total ratio of the polymerizable monomer and the non-polymerizable monomer to the liquid crystal composition is also included. Usually, it is 0.2% by mass or more, preferably 1.2% by mass or more, and is usually 10% by mass or less, preferably 7% by mass or less. If this ratio is too small, the repetition durability of the liquid crystal element is inferior, and if it is too large, the haze at the time of transparency may be large and the haze at the time of opaqueness may be small.

<Chiral Nematic Liquid Crystal>
The chiral nematic liquid crystal used in the liquid crystal element and the liquid crystal composition of the present invention has a positive dielectric anisotropy. Since the dielectric anisotropy of the chiral nematic liquid crystal of the present invention is positive, it is possible to drive in the reverse mode.
The dielectric anisotropy value (Δε) of the chiral nematic liquid crystal is not particularly limited as long as it is positive, but is preferably 5 or more, and more preferably 8 or more for reducing the driving voltage of the liquid crystal element. In addition, it is preferable that individual molecules constituting the chiral nematic liquid crystal do not have absorption with a wavelength longer than 350 nm from the viewpoint of shortening the curing time of the polymerizable monomer.

As the chiral nematic liquid crystal, the liquid crystal itself may be an assembly of liquid crystalline compounds exhibiting a cholesteric phase, or a chiral nematic liquid crystal may be formed by adding a chiral agent to the nematic liquid crystal. From the viewpoint of designing the liquid crystal composition, it is preferable to add a chiral agent to the nematic liquid crystal according to the purpose and control the chiral pitch length (p) and the liquid crystal-isotropic phase transition temperature (Tni).

Relationship between the chiral pitch length p of the chiral nematic liquid crystal of the present invention and the distance d between the substrates with electrodes
d / p is preferably 1 or more. More preferably, it is 2 or more, particularly preferably 4 or more. Moreover, it is preferable that it is 20 or less, and it is especially preferable that it is 12 or less. d / p
The larger the value, the greater the scattering during driving and the light-shielding characteristics.However, the drive voltage of the liquid crystal element also increases at the same time.Therefore, from the viewpoint of both the light-shielding characteristics and energy saving and safety, it is within the above range. It is preferable to accommodate.

The p of the chiral nematic liquid crystal is preferably 0.3 μm or more, and more preferably 0.8 μm or more. On the other hand, it is preferably 3 μm or less, more preferably 2 μm or less.
If p is too small, the driving voltage of the liquid crystal element tends to be high, and if it is too large, the contrast tends to be poor. In general, since p is inversely proportional to the concentration of the chiral agent, the concentration of the chiral agent may be determined by calculating backward from the necessary value of p. When p × n (n is the refractive index of chiral nematic liquid crystal) is in the range of visible light wavelength (380 nm to 800 nm), the finally obtained liquid crystal element is colored when no voltage is applied, and is out of the visible light range. In this case, since it becomes colorless and transparent when no voltage is applied, p may be selected according to the purpose.

The distance d between the substrates with electrodes of the screen of the present invention needs to be not less than p of the chiral nematic liquid crystal to be used, and is usually preferably 2 μm or more, more preferably 5 μm or more. Moreover, 100 micrometers or less are preferable and 20 micrometers or less are still more preferable.
The light transmittance of the screen when no voltage is applied decreases with increasing d, and the response time of the display may become longer. On the other hand, if d is too small, the light-shielding characteristic during driving is reduced, and in the case of a large area screen, the screen may be short-circuited. By being in the above range, these requirements can be satisfied in a balanced manner.

  Tni of the chiral nematic liquid crystal is preferably 50 ° C. or higher and more preferably 70 ° C. or higher because the upper limit temperature at which the liquid crystal element can operate is determined by Tni of the chiral nematic liquid crystal. On the other hand, as Tni increases, the viscosity tends to increase, so that it is preferably 200 ° C. or lower, and more preferably 150 ° C. or lower.

  The nematic liquid crystal may be any known one, and the molecular skeleton, substituent, and molecular weight of the constituent molecules are not particularly limited, and may be a synthetic product or a commercial product. It is preferable that the dielectric anisotropy of the nematic liquid crystal is positive and large in order to make the dielectric anisotropy of the chiral nematic liquid crystal phase of the liquid crystal element and the chiral nematic liquid crystal of the liquid crystal composition positive. In addition, it is preferable that the constituent molecules have no absorption of wavelengths longer than 350 nm from the viewpoint of shortening the curing time of the polymerizable monomer.

  When using a known liquid crystal substance, specifically, the Japan Society for the Promotion of Science 142nd edition; “Liquid Crystal Device Handbook”, Nihon Kogyo Shimbun (1989), pages 152 to 192 and the Liquid Crystal Handbook Editorial Committee Chapter: “Liquid Crystal Handbook” Maruzen Co., Ltd. (2000), using various low molecular compounds such as biphenyl, phenylcyclohexane and cyclohexylcyclohexane or mixtures as described in pages 260 to 330 can do. In addition, a high molecular weight compound or a mixture described in “Liquid Crystal Handbook” Maruzen Co., Ltd. (2000), pages 365 to 415, edited by the Liquid Crystal Handbook Editorial Committee, can also be used. As a compound constituting a nematic liquid crystal, for example,

Etc. As the cholesteric liquid crystal and nematic liquid crystal, those having low viscosity and high dielectric anisotropy are preferable from the viewpoint of high-speed response of the liquid crystal element and ease of production of the liquid crystal element.

The chiral agent may be any chiral compound that is compatible with the host liquid crystal, may be a synthetic product or a commercial product, may exhibit liquid crystal properties, or may have a polymerizable functional group. good. Further, dextrorotatory or levorotatory may be used, and a dextrorotatory chiral agent and a levorotatory chiral agent may be used in combination. In addition, as the chiral agent, those having a large dielectric anisotropy per se and a low viscosity are preferable from the viewpoint of reduction in driving voltage and response speed of the liquid crystal element, and the chiral agent is an index of the force for twisting the liquid crystal. Larger Helical Twisting Power is preferable. Moreover, it is preferable that it does not have absorption longer than 350 nm in terms of shortening the curing time of the polymerizable monomer.
Examples of the chiral agent include CB15 (trade name, manufactured by Merck), C15 (trade name, manufactured by Merck), S-811 (trade name, manufactured by Merck), R-811 (trade name, manufactured by Merck), S-1011 ( Trade name Merck), R-1011 (trade name Merck) and the like.

<Radical polymerization initiator>
As the radical polymerization initiator, the molecular structure is not particularly limited, but it is preferable to select a compound that is soluble in the host liquid crystal. In addition, since the molecules constituting the liquid crystal composition of the present invention typically have ultraviolet light absorption of a wavelength of 350 nm or less, it is preferable to select a radical polymerization initiator that is radicalized by light having a wavelength of 350 nm or more.

As the radical polymerization initiator, it is preferable to use those represented by the following general formula (7) and / or (9). By producing a liquid crystal element using the monomer of the present invention and the initiator represented by the general formula (7) and / or (9), the planar structure of the liquid crystal can be obtained even when cured at high illuminance and in a short time. In the liquid crystal element obtained without being disturbed, the driving does not deteriorate, the driving in the reverse mode is possible, and there is a tendency to show high contrast and high-speed response.

Although the liquid crystal composition of the present invention is cured at high speed with strong light intensity, the planar structure of the liquid crystal is not disturbed, and as a result, the device does not deteriorate, and the reverse mode exhibits high contrast and colorlessness. The factor for realizing the liquid crystal element is not always clear. However, since the polymerization initiator represented by the general formula (7) and / or (9) effectively absorbs high-energy short-wavelength ultraviolet light to generate radicals, it adversely affects deterioration and driving of the liquid crystal element. It is presumed that the amount of the polymerization initiator added can be reduced.

[In general formula (7),
X ¹⁰ represents a hydroxy group, an aromatic hydrocarbon group which may have a substituent, an aromatic heterocyclic group which may have a substituent, an alkyl group which may have a substituent, a substituent An acyl group which may have a group, a carbonyl group which may have a substituent, an alkoxy group which may have a substituent or an amino group which may have a substituent,
X ¹¹ represents a hydrogen atom, an aromatic hydrocarbon which may have a substituent, an aromatic heterocyclic group which may have a substituent, or an alkyl group which may have a substituent. ]

<Polymerization initiator represented by general formula (7)>
X ¹⁰ represents a hydroxy group, an aromatic hydrocarbon group which may have a substituent, an aromatic heterocyclic group which may have a substituent, an alkyl group which may have a substituent, a substituent An acyl group which may have a group, a carbonyl group which may have a substituent, an alkoxy group which may have a substituent or an amino group which may have a substituent.
Examples of the aromatic hydrocarbon group for X ¹⁰ include a monovalent group obtained by removing one hydrogen atom from a single ring or a condensed ring formed by condensing 2 to 4 thereof. Specific examples include: Examples include a benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, perylene ring, tetracene ring, pyrene ring, benzpyrene ring, chrysene ring, triphenylene ring, acenaphthene ring, fluoranthene ring, fluorene ring and the like. Among these, the number of carbon atoms is preferably 6 or more, and the number of carbon atoms is preferably 18 or less, more preferably 14 or less, and particularly preferably 12 or less for absorption of ultraviolet light having a short wavelength.

Examples of the aromatic heterocyclic group represented by X ¹⁰ include a monovalent group obtained by removing one hydrogen atom from a monocyclic ring or a condensed ring formed by condensing 2 to 4 thereof. Specific examples include: , Furan ring, benzofuran ring, thiophene ring, benzothiophene ring, pyrrole ring, pyrazole ring, imidazole ring, oxadiazole ring, indole ring, carbazole ring, pyrroloimidazole ring, pyrrolopyrazole ring, pyrrolopyrrole ring, thienopyrrole ring, thieno Thiophene ring, furopyrrole ring, furofuran ring, thienofuran ring, benzisoxazole ring, benzisothiazole ring, benzimidazole ring, pyridine ring, pyrazine ring, pyridazine ring, pyrimidine ring, triazine ring, quinoline ring, isoquinoline ring, cinoline ring, Quinoxaline ring, phenanthridine ring, benzo Examples include imidazole ring, perimidine ring, quinazoline ring, quinazolinone ring, and azulene ring. Among these, the number of carbon atoms is preferably 1 or more, and the number of carbon atoms is preferably 18 or less, more preferably 14 or less, and particularly preferably 12 or less for absorption of ultraviolet light having a short wavelength.

The substituent that the aromatic hydrocarbon group and aromatic heterocyclic group of X ¹⁰ may have is not particularly limited as long as the effects of the present invention are not impaired, but a halogen atom and a carbon number of 1 to 1 Examples include 20 alkyl groups, alkoxy groups having 1 to 20 carbon atoms, aromatic hydrocarbon groups, and aromatic heterocyclic groups.

As the alkyl group which may have a substituent X ^10, a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, heptyl group, octyl group, nonyl group, decyl group, dodecyl group A linear alkyl group: a branched alkyl group such as isopropyl group, isobutyl group, sec-butyl group, tert-butyl group, isooctyl group, isononyl group; cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cyclopropylmethyl And cyclic alkyl groups such as a group, a cyclohexylmethyl group, and a 4-butylmethylcyclohexyl group. Among these, it is preferable that the number of carbon atoms is 1 or more, and that the number of carbon atoms is preferably 20 or less, and that the number of carbon atoms is 16 or less is high reactivity of a radical generated by a molecule that has been absorbed by light and cleaved. Therefore, it is preferable.
Examples of the substituent that the alkyl group of X ¹⁰ may have include a halogen atom, a hydroxy group, an alkoxy group having 1 to 20 carbon atoms, an alkoxycarbonyl group having 2 to 20 carbon atoms, and a cyano group.

Examples of the acyl group which may have a substituent of X ¹⁰ include saturated aliphatic acyl groups such as formyl group and acetyl group; saturated aliphatic acyl groups such as oxalyl group and malonyl group; unsaturated fats such as acryloyl group Group acyl groups; carbocyclic acyl groups such as benzoyl groups and phthaloyl groups. Among these, it is preferable that the number of carbon atoms is 1 or more, and that the number of carbon atoms is preferably 20 or less, and that the number of carbon atoms is 16 or less is high reactivity of a radical generated by a molecule that has been absorbed by light and cleaved. Therefore, it is preferable.

The alkoxycarbonyl group which may have a substituent X ^10, a methoxycarbonyl group, an ethoxycarbonyl group, an alkoxycarbonyl group having 2 to 20 carbon atoms such as t- butoxycarbonyl group. Among these, an alkoxycarbonyl group having 6 or less carbon atoms is preferable because of high reactivity of the generated radical.
As the alkoxycarbonyl substituent which may be group have the X ^10, 1 carbon atoms
-20 alkyl groups, aromatic hydrocarbon groups and the like.

The amino group which may have a substituent X ^10, monomethylamine group, dimethylamine group, an imino group, imidazole group, Biperijin group, a morpholino group, triazine group. Among these, it is preferable because of the high reactivity of a radical generated by an amino group having a substituent having 6 or less carbon atoms.
Among them, X ¹⁰ is preferably an aromatic hydrocarbon group which may have a substituent having 12 or less carbon atoms because of absorption of ultraviolet light having a short wavelength.

X ¹¹ represents a hydrogen atom, an aromatic hydrocarbon group which may have a substituent, an aromatic heterocyclic group which may have a substituent, or an alkyl group which may have a substituent. .
In the polymerization initiator represented by the general formula (1), it is preferable from the viewpoint of reactivity that the carbon atom of X ¹¹ bonded to X ¹⁰ —C (═O) — becomes electron rich. In order to make the carbon atom rich in electrons, for example, a ring in which the carbon atom of X ¹¹ bonded to X ¹⁰ -C (═O) — contains a hetero atom such as hydroxy group, N and / or O, etc. It preferably has an electron-donating substituent.
The aromatic hydrocarbon group which may have a substituent of X ¹¹ has the same meaning as the aromatic hydrocarbon group which may have a substituent mentioned in X ¹⁰ and may have it. The substituent is also synonymous. Among these, it is preferable that the number of carbon atoms is 6 or more, and that the number of carbon atoms is 18 or less, further 14 or less, and particularly 12 or less is the absorption of short wavelength ultraviolet light and the high reactivity of the generated radicals. Therefore, it is preferable.

The aromatic heterocyclic group which may have a substituent of X ¹¹ has the same meaning as the aromatic heterocyclic group which may have a substituent mentioned in X ¹⁰ and may have it. The substituent is also synonymous. Among these, the number of carbon atoms is preferably 1 or more, and the number of carbon atoms is 18 or less, more preferably 14 or less, and particularly 12 or less, because absorption of short-wavelength ultraviolet light and high reactivity of generated radicals are high. Therefore, it is preferable.

The alkyl group which may have a substituent for X ¹¹ has the same meaning as the alkyl group which may have a substituent described for X ¹⁰ . Among these, it is preferable that the number of carbon atoms is 1 or more, and it is preferable that the number of carbon atoms is 20 or less, and that the number of carbon atoms is 16 or less is high reactivity of a radical generated by a molecule that has been cleaved by light absorption. Therefore, it is preferable. Further, the alkyl group may form a ring.
Examples of the substituent that the alkyl group of X ¹¹ may have include an electron donating group such as a ring containing a hetero atom such as a hydroxyl group, an alkoxy group, an amino group, a methylamino group, a methyl group, N, and / or O. Groups such as nitro group, cyano group, halogen atom, phenyl group and keto group. Among these, a group which gives an electron donating property to the carbon atom of X ¹¹ bonded to X ¹⁰ —C (═O) — is preferable.
Although the substitution position of the substituent that the alkyl group may have is not particularly limited, it is possible to cleave the molecule by being bonded to the carbon atom of X ¹¹ bonded to X ¹⁰ -C (═O)-. It is preferable from the point of being easy to do.

Among them, X ¹¹ is preferably a cyclic or chain alkyl group which may have a substituent having 12 or less carbon atoms and an aromatic hydrocarbon group because of absorption of ultraviolet light having a short wavelength.
The combination of X ¹⁰ and X ¹¹ is not particularly limited, but it is preferable that at least one of them has a cyclic structure, and it is preferable that both have a cyclic structure because of high reactivity.

  Of the general formula (7), the general formula (8) is preferable from the viewpoint of absorption of ultraviolet light having a short wavelength and high reactivity with the polymerizable monomer.

X ¹² represents an optionally substituted cyclic alkyl group, or an alkyl group having a cyclic structure as a substituent.

Specific examples of the cyclic alkyl group which may have a substituent for X ¹² include cyclic groups in the alkyl group which may have a substituent described for X ¹⁰ .
Among these, it is preferable that the number of carbon atoms is 1 or more, and it is preferable that the number of carbon atoms is 20 or less, and that the number of carbon atoms is 16 or less is high reactivity of a radical generated by a molecule that has been cleaved by light absorption. Therefore, it is preferable.
Examples of the substituent that the alkyl group of X ¹² may have include an electron donating group such as a ring containing a hetero atom such as a hydroxyl group, an alkoxy group, an amino group, a methylamino group, a methyl group, N, and / or O. Electron withdrawing groups such as nitro group, cyano group, halogen atom, phenyl group and keto group. Among these, a group that imparts an electron donating property to the carbon atom of X ¹² bonded to —C (═O) — is preferable.
The substitution position of the substituent that the alkyl group may have is not particularly limited. However, bonding to the carbon atom of X ¹² bonded to —C (═O) — causes cleavage of the molecule. It is preferable from the viewpoint of easy.

The cyclic structure of the alkyl group having as a substituent a group having a cyclic structure X ^12, ring containing a heteroatom such as N and / or O, such as alkenyl groups and cyclic alkynyl groups of cyclic and the like.
In addition, the alkyl group having a cyclic structure as a substituent is preferably a chain, and among them, the number of carbon atoms is preferably 1 or more, the number of carbons is preferably 10 or less, and the number of carbon atoms is 6 The following is preferable because of the high reactivity of the radical generated by the molecule that has been cleaved by light absorption.

  Specific examples of the polymerization initiator represented by the general formula (7) are shown below, but are not limited thereto.

  As the radical polymerization initiator, a polymerization initiator represented by the general formula (9) is also preferably used.

[In the general formula (9),
X ¹⁰ represents one atom selected from the elements of Groups 14, 15 and 16;
X ¹¹ and X ¹² are each independently an alkyl group which may have a substituent, an aromatic hydrocarbon group which may have a substituent, or an aromatic complex which may have a substituent. Represents a cyclic group,
X ¹³ and X ¹⁴ each independently have a direct bond, an alkyl group which may have a substituent, an aromatic hydrocarbon group which may have a substituent, or a substituent. Represents an aromatic heterocyclic group,
A ¹ represents an oxygen atom, an alkyl group which may have a substituent, or —O—R ⁵⁰ group, and R ⁵⁰ has a hydrogen atom, an alkyl group which may have a substituent, or a substituent. Represents an optionally substituted aromatic hydrocarbon group or an optionally substituted aromatic heterocyclic group,
A ² represents an alkyl group that may have a substituent, an aromatic hydrocarbon group that may have a substituent, or an aromatic heterocyclic group that may have a substituent,
n represents an integer of 1 to 5. ]

  A polymerization initiator will not be specifically limited if it is a structure represented by the said General formula (9), It is preferable that it produces | generates a some radical when energy is given.

<Polymerization initiator represented by general formula (9)>
X ^{10 in the} general formula (9) represents one atom selected from the elements of Groups 14, 15, and 16. Among these, nonmetallic elements or metalloid elements are preferable from the viewpoint of radical generation efficiency, and nonmetallic elements are particularly preferable. Among nonmetallic elements, phosphorus atom, oxygen atom, nitrogen atom, sulfur atom, and carbon atom are particularly preferable from the viewpoint of radical generation efficiency.

X ¹¹ and X ^{12 in} the general formula (9) each independently have an alkyl group which may have a substituent, an aromatic hydrocarbon group which may have a substituent, or a substituent. Represents an aromatic heterocyclic group which may be used.
Examples of the alkyl group which may have a substituent of X ¹¹ and X ^{12 in} the general formula (9) include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, Linear alkyl groups such as nonyl, decyl and dodecyl; branched alkyl groups such as isopropyl, isobutyl, sec-butyl, tert-butyl, isooctyl and isononyl; cyclopropyl, cyclobutyl, Examples thereof include cyclic alkyl groups such as a cyclopentyl group, a cyclohexyl group, a cyclopropylmethyl group, a cyclohexylmethyl group, and a 4-butylmethylcyclohexyl group. Among these, the number of carbon atoms is preferably 1 or more, and on the other hand, the number of carbon atoms is preferably 20 or less, and the number of carbon atoms is preferably 16 or less because the light absorption wavelength during polymerization becomes longer and the reaction becomes easier. .
Examples of the substituent that the alkyl group represented by X ¹¹ and X ¹² may have include a halogen atom, an alkoxy group having 1 to 20 carbon atoms, an alkoxycarbonyl group having 2 to 20 carbon atoms, and a cyano group. It is done.

The aromatic hydrocarbon group which may have a substituent of X ¹¹ and X ¹² is 1 obtained by removing one hydrogen atom from a single ring or a condensed ring formed by condensing 2 to 4 thereof. Specific examples include benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, perylene ring, tetracene ring, pyrene ring, benzpyrene ring, chrysene ring, triphenylene ring, acenaphthene ring, fluoranthene ring, fluorene ring. And the like. Among these, it is preferable that the number of carbon atoms is 6 or more, and that the number of carbon atoms is 18 or less, further 14 or less, the light absorption wavelength at the time of polymerization becomes longer, and the overlap of the absorption wavelength with the polymerization monomer is reduced. This is preferable because the radical generation efficiency of the polymerization initiator is increased.

The aromatic heterocyclic group which may have a substituent of X ¹¹ and X ¹² is obtained by removing one hydrogen atom from a monocyclic ring or a condensed ring formed by condensing 2 to 4 thereof. Examples of the monovalent group include a furan ring, a benzofuran ring, a thiophene ring, a benzothiophene ring, a pyrrole ring, a pyrazole ring, an imidazole ring, an oxadiazole ring, an indole ring, a carbazole ring, a pyrroloimidazole ring, Pyrrolopyrazole ring, pyrrolopyrrole ring, thienopyrrole ring, thienothiophene ring, furopyrrole ring, furofuran ring, thienofuran ring, benzisoxazole ring, benzoisothiazole ring, benzimidazole ring, pyridine ring, pyrazine ring, pyridazine ring, pyrimidine ring, Triazine ring, quinoline ring, isoquinoline ring, sinoline ring, quinoki Phosphorus ring, phenanthridine ring, benzimidazole ring, perimidine ring, a quinazoline ring, a quinazolinone ring, groups such as azulene ring. Among these, it is preferable that the number of carbon atoms is 1 or more, and that the number of carbon atoms is 18 or less, further 14 or less, the light absorption wavelength at the time of polymerization becomes longer, and the overlap of the absorption wavelength with the polymerization monomer is increased. This is preferable because the radical generation efficiency of the polymerization initiator can be reduced.

The substituent that the aromatic hydrocarbon group and aromatic heterocyclic group of X ¹¹ and X ¹² may have is not particularly limited as long as the effects of the present invention are not impaired, but a halogen atom, a carbon number Include an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, an aromatic hydrocarbon group, and an aromatic heterocyclic group.
Among these, X ¹¹ and X ¹² are particularly preferable because the aromatic hydrocarbon having a substituent has a longer light absorption wavelength at the time of polymerization and is likely to react. X ¹¹ and X ¹² may be the same or different, but are preferably the same from the viewpoint of ease of reaction control during polymerization.

A ^{1 in the} general formula (9) represents an oxygen atom, an alkyl group which may have a substituent, or an —O—R ⁵⁰ group.
The alkyl group which may have a substituent for A ¹ is specifically defined as that described for X ¹¹ , and the substituent which may be present is also synonymous. Among these, the number of carbon atoms is preferably 1 or more, more preferably 20 or less carbon atoms, and 16 or less carbon atoms, the light absorption wavelength during polymerization becomes longer, and the absorption wavelength with the polymerization monomer. Is preferable because the radical generation efficiency of the polymerization initiator is increased.

R ⁵⁰ represents a hydrogen atom, an alkyl group that may have a substituent, an aromatic hydrocarbon group that may have a substituent, or an aromatic heterocyclic group that may have a substituent.
Specific examples of the alkyl group which may have a substituent of R ⁵⁰ have the same meaning as the alkyl group of X ¹¹ , and the substituent which may have a substituent is also the same. The alkyl group which may have a substituent for R ⁵⁰ preferably has 1 or more carbon atoms, preferably 15 or less, more preferably 10 or less, and even more preferably 5 or less. More preferably, it is more preferably 3 or less, since the light absorption wavelength at the time of polymerization becomes longer, the overlap of the absorption wavelength with the polymerization monomer can be reduced, and the radical generation efficiency of the polymerization initiator is increased.

In addition, the aromatic hydrocarbon group which may have a substituent of R ^{50 and} the aromatic heterocyclic group which may have a substituent are synonymous with X ¹¹ and X ¹² and have The substituents that may be used are also synonymous. The aromatic hydrocarbon group which may have a substituent of R ¹⁰ preferably has 6 or more carbon atoms, preferably 18 or less carbon atoms, and 14 or less carbon atoms, The light absorption wavelength at the time of polymerization is increased, the overlap of the absorption wavelength with the polymerization monomer can be reduced, and the radical generation efficiency of the polymerization initiator is increased, which is preferable.

The aromatic heterocyclic group which may have a substituent of R ⁵⁰ preferably has 1 or more carbon atoms, preferably 18 or less carbon atoms, and 14 or less carbon atoms, The light absorption wavelength at the time of polymerization is increased, the overlap of the absorption wavelength with the polymerization monomer can be reduced, and the radical generation efficiency of the polymerization initiator is increased, which is preferable.
Among the above, A ¹ represents an oxygen atom; that number of carbon atoms of R ⁵⁰ 5 or less, still more preferably -O-R ⁵⁰ group is 3 or less alkyl group; 1 or more carbon atoms, alkyl group of 4 or less It is preferable because the light absorption wavelength at the time of polymerization becomes longer, the overlap of the absorption wavelength with the polymerization monomer can be reduced, and the radical generation efficiency of the polymerization initiator is increased.
For convenience of description, the bond between A ¹ and X ¹⁰ is represented by a single bond, but when A ¹ is an oxygen atom, the bond is a double bond.

A ^{2 in the} general formula (9) is an alkyl group which may have a substituent, an aromatic hydrocarbon group which may have a substituent, or an aromatic heterocyclic ring which may have a substituent. Represents a group.
Specific examples of the alkyl group which may have a substituent A ² has the same meaning as the alkyl group of A ^1, is also synonymous substituent which may have. The alkyl group which may have a substituent of A ² preferably has 1 or more carbon atoms, preferably 20 or less carbon atoms, and 16 or less carbon atoms during polymerization. The light absorption wavelength is increased, the overlap of the absorption wavelength with the polymerization monomer can be reduced, and the radical generation efficiency of the polymerization initiator is increased, which is preferable. In addition, the aromatic hydrocarbon group which may have a substituent of A ^{2 and} the aromatic heterocyclic group which may have a substituent are synonymous with X ¹¹ and X ¹² and have The substituents that may be used are also synonymous. The aromatic hydrocarbon group which may have a substituent of A ² preferably has 6 or more carbon atoms, preferably 18 or less carbon atoms, and 14 or less carbon atoms, The light absorption wavelength at the time of polymerization is increased, the overlap of the absorption wavelength with the polymerization monomer can be reduced, and the radical generation efficiency of the polymerization initiator is increased, which is preferable.

The aromatic heterocyclic group which may have a substituent for A ² preferably has 1 or more carbon atoms, preferably 18 or less carbon atoms, and 14 or less carbon atoms, The light absorption wavelength at the time of polymerization is increased, the overlap of the absorption wavelength with the polymerization monomer can be reduced, and the radical generation efficiency of the polymerization initiator is increased, which is preferable.
Among these, A ² is an alkyl group which may have a substituent, and an aromatic hydrocarbon group which may have a substituent, so that the light absorption wavelength at the time of polymerization becomes longer, and the polymerization monomer This is particularly preferable because it can reduce the overlap of absorption wavelengths with the polymerization initiator and increase the radical generation efficiency of the polymerization initiator.
X ¹³ and X ¹⁴ each independently have a direct bond, an alkyl group which may have a substituent, an aromatic hydrocarbon group which may have a substituent, or a substituent. Represents an aromatic heterocyclic group.

Specific examples of the alkyl group which may have a substituent of R ⁵⁰ have the same meaning as the alkyl group of X ¹¹ , and the substituent which may have a substituent is also the same. The alkyl group which may have a substituent of X ¹³ and X ¹⁴ is preferably independently of 1 or more, preferably 20 or less, and preferably 15 or less. It is preferable that the light absorption wavelength at the time of polymerization is increased, the overlap of the absorption wavelength with the polymerization monomer can be reduced, and the radical generation efficiency of the polymerization initiator is increased. As the substituent aromatic optionally having a hydrocarbon group and may have a substituent aromatic heterocyclic group X ¹³ and X ^14, has the same meaning as X ^11, have The substituents that may be used are also synonymous. The aromatic hydrocarbon group which may have a substituent of X ¹³ and X ¹⁴ preferably has 6 or more carbon atoms, and preferably has 18 or less carbon atoms, and 14 or less carbon atoms. It is preferable because the light absorption wavelength at the time of polymerization becomes longer, the overlap of the absorption wavelength with the polymerization monomer can be reduced, and the radical generation efficiency of the polymerization initiator is increased.

The aromatic heterocyclic group which may have a substituent of X ¹³ and X ¹⁴ preferably has 1 or more carbon atoms, preferably 18 or less carbon atoms, and 14 or less carbon atoms. It is preferable because the light absorption wavelength at the time of polymerization becomes longer, the overlap of the absorption wavelength with the polymerization monomer can be reduced, and the radical generation efficiency of the polymerization initiator is increased.
Among these, X ¹³ and X ¹⁴ are preferably an aromatic hydrocarbon group which may have a direct bond or a substituent from the viewpoint of reactivity. X ¹³ and X ¹⁴ may be the same or different, but are preferably the same from the viewpoint of reactivity.

n represents an integer, and the upper limit is not particularly limited as long as the effect of the present invention is not impaired, but is preferably 5 or less, and preferably 3 or less to prevent storage stability and dark reaction during polymerization. Therefore, it is preferable. When n is 2 or more, the polymerization initiator represented by the general formula (1) has a plurality of A ¹ , but the plurality of A ¹ may be the same or different. The same applies to A ² , X ¹⁴ , and X ¹³ .

  Specific examples of the polymerization initiator represented by the general formula (9) are shown below, but are not limited thereto.

X ²⁰ and X ^{20 ′} each independently represent a group 14 to group 16 atom, and R ^{20 to} R ^2.
3 represents an alkyl group having 1 to 20 carbon atoms which may be independently substituted. Moreover, the said phenyl group and phenylene group may have a C1-C10 alkyl group.

One type of polymerization initiator represented by the general formula (7) and / or (9) may be used, or a plurality thereof may be used in combination. Moreover, you may use in combination with other polymerization initiators other than the polymerization initiator represented by General formula (7) and / or (9) in the range which does not impair the effect of this invention. The molecular structure is not particularly limited, but it is preferable to select a compound that can be dissolved in the host liquid crystal.
In addition, since the molecules constituting the liquid crystal composition of the present invention typically absorb ultraviolet light having a wavelength of 300 nm or less, the radical polymerization initiator itself is selected to be radicalized by light having a wavelength of around 350 nm or less. Is preferred.

  Other radical polymerization initiators include acylphosphine oxides, alkylphenones, titanocenones, polyhalogen compounds, alkyl boron salts of cyanine dyes, triarylimidazoles, and the like. Specifically, alpha, alpha-dimethoxy-alpha-phenylacetophenone (IRGACURE651), 2-methyl-1- (4- (methylthio) phenyl) -2- (4-morpholinyl) -1-propanone (IRGACURE907), 2 -Benzyl-2- (dimethylamino) -1- (4- (4-morpholinyl) phenyl) -1-butanone (IRGACURE369) and the like.

The content ratio of the polymerization initiator represented by the general formula (7) and / or (9) is usually 0.01% by mass or more, preferably 0.05% by mass or more in the liquid crystal composition, Usually, it is 5 mass% or less, preferably 1 mass% or less. By being in this range, the polymerization is sufficient, and the repetition durability of the liquid crystal element obtained from the liquid crystal composition and the haze at the time of transparency tend to be improved.
In addition to the polymerization initiator represented by the general formula (7) and / or (9), when using another polymerization initiator, it is preferably used within the above range, and the general formula (7 ) And / or the ratio of the polymerization initiator represented by (7) and the other polymerization initiator is preferably 50:50 to 70:30 in order to obtain the effects of the present invention.

<Others>
The chiral nematic liquid crystal phase of the liquid crystal element of the present invention includes a polymerization initiator, a light stabilizer, an antioxidant, a thickener, a polymerization inhibitor, a photosensitizer, an adhesive, an antifoaming agent, a surfactant, and the like. You may have.
Moreover, content of the said other component can be mix | blended in arbitrary ratios in the range which does not impair the performance of the liquid crystal element of this invention.

<Use of liquid crystal composition>
The liquid crystal composition of the present invention can be used as a liquid crystal element described later having a layer containing the cured product.

<Liquid crystal element>
In the liquid crystal element of the present invention, at least one of the substrates is a transparent substrate, and a liquid crystal light control layer including a pair of substrates with electrodes arranged opposite to each other and a composite of a chiral nematic liquid crystal and a polymer resin is sandwiched between the substrates. Thus, the liquid crystal light control layer is obtained by photocuring a liquid crystal composition composed of a polymerizable monomer and a chiral nematic liquid crystal.
The liquid crystal element of the present invention is not particularly limited as long as it is the above liquid crystal element, but a typical structure will be described below.

<Applications of liquid crystal elements>
The liquid crystal composition and liquid crystal element of the present invention can be used for screens, displays and the like. For example, it can be used as a display panel or projection panel, such as a screen for blocking the visual field such as a building window, a partition and a show window, or by electrically switching the display with high-speed response. it can.
The projection system is not particularly limited, such as a front projection or a rear projection. For example, the rear projection system disclosed in Japanese Patent Laid-Open No. 6-82748 or International Publication WO 2009/150579, or Japanese Patent Laid-Open No. 2010-217291 is shown. And a projection system using coherent light as a light source.

Examples of the material of the substrate include colorless transparent or colored transparent or opaque materials such as inorganic transparent materials such as glass and quartz, metals, metal oxides, semiconductors, ceramics, plastic plates, and plastic films. On the substrate, for example, a thin film of metal oxide, metal, semiconductor, organic conductive material or the like is formed on the entire surface of the substrate or partially by a known coating method, printing method, vapor deposition method such as sputtering, or the like. is there. Alternatively, it may be partially etched after forming a conductive thin film. In particular, in order to obtain a large-area liquid crystal device, from the viewpoint of productivity and workability, an ITO (mixture of indium oxide and tin oxide) electrode on a transparent polymer film such as PET is deposited by sputtering or printing. It is desirable to use an electrode substrate formed using A wiring for connecting the electrodes or connecting the electrodes and the outside may be provided on the substrate. For example, a segment driving electrode substrate, a matrix driving electrode substrate, an active matrix driving electrode substrate, or the like may be used. Furthermore, the electrode surface provided on the substrate is a protective film or alignment film made of an organic compound such as polyimide, polyamide, silicon, and cyanide, an inorganic compound such as SiO ₂ , TiO ₂ , and ZrO ₂ , or a mixture thereof. The entire surface or a part thereof may be covered. The substrate may be aligned so that the liquid crystal is aligned with respect to the surface of the substrate. When the alignment is processed, any alignment processing can be used as long as the liquid crystal composition in contact has a planar structure. It doesn't matter. For example, the two substrates may be in a homogeneous orientation, or may be a so-called hybrid in which one is homogeneous orientation and the other is homeotropic orientation. For these alignment treatments, the electrode surface may be directly rubbed, or a normal alignment film such as polyimide used for TN liquid crystal, STN liquid crystal or the like may be used. In addition, as a method for producing the alignment film, a so-called photo-alignment method may be used in which the organic thin film on the substrate is irradiated with light having anisotropy such as linearly polarized light to give the film anisotropy. Note that, when the liquid crystal element is manufactured, the alignment treatment of the substrate is not necessarily required if the alignment of the uncured liquid crystal composition can be controlled with respect to the substrate surface. That is, before the liquid crystal composition of the present invention is photocured, the liquid crystal composition can be aligned to take a planar structure by a method such as flowing the liquid crystal composition or applying a shear stress.

  The opposing substrate may have an adhesive layer containing a resin body for adhering and supporting the substrate as appropriate at the peripheral part. Note that the end face of the liquid crystal element or the injection port of the liquid crystal composition in the present invention is used as an adhesive tape , Tapes such as thermosetting tapes, and / or thermosetting resins, photocurable resins, moisture curable resins, room temperature curable adhesives, anaerobic adhesives, epoxy adhesives, silicone adhesives Sealing with a curable resin such as an adhesive, a fluorine resin adhesive, a polyester adhesive, a vinyl chloride adhesive, or a thermoplastic resin can prevent the internal liquid crystal from seeping out. In addition, this sealing may work to prevent deterioration of the liquid crystal element at the same time. In this case, the end face may be protected by covering the entire end face, or by pouring a curable resin or thermoplastic resin from the end face into the liquid crystal element and solidifying it. It may be covered with tapes.

  Spacers such as spherical or cylindrical glass, plastic, ceramic, or plastic film may be present between the substrates arranged to face each other. The spacer may be present as a component of the liquid crystal composition of the present invention so that it may be present in the liquid crystal light control layer between the substrates. The spacer is dispersed on the substrate during the assembly of the liquid crystal element or mixed with an adhesive. And may be present in the adhesive layer.

  The liquid crystal light control layer of the liquid crystal element of the present invention is, for example, formed as a sealed cell by forming an adhesive layer with a photocurable adhesive or the like at a peripheral portion of a pair of substrates with electrodes arranged opposite to each other via a spacer. Two or more adhesive layer cutouts are immersed and injected into the liquid crystal composition of the present invention under normal pressure or vacuum, or a liquid crystal composition is applied onto one substrate using a coater, and After being sandwiched by a known method such as stacking the other substrate on the substrate, it is formed by polymerization and curing with radiation such as ultraviolet light, visible light, or electron beam. In the case of a plastic film substrate, a substrate with electrodes that is continuously supplied is sandwiched between two rubber rolls, and a mixture of a liquid crystal containing a spacer and dispersed therein and an uncured curable compound is interposed between the substrates, and then sandwiched. Productivity is high because it can be photocured continuously. In any method, when the substrate is not subjected to alignment treatment, the liquid crystal composition is flowed before the uncured liquid crystal composition is photocured, or a shear stress is applied to the liquid crystal. It is necessary that the composition is oriented to assume a planar structure. Specifically, the liquid crystal composition can have a planar structure by injecting the liquid crystal composition of the present invention into a sealed cell that has not been subjected to alignment treatment.

Among photocuring methods, curing with ultraviolet rays is particularly preferable. The light source for photopolymerization may be any light source having a spectrum at the absorption wavelength of the radical photopolymerization initiator used, and typically any light source capable of irradiating light with a wavelength of 220 nm to 450 nm. . Examples include a high pressure mercury lamp, an ultra high pressure mercury lamp, a halogen lamp, a metal halide lamp, a UV-LED, a blue LED, a white LED, and the like. In addition, a heat ray cut filter, an ultraviolet ray cut filter, a visible light cut filter, or the like may be used in combination. Light may be applied to at least one surface from the transparent substrate of the liquid crystal element, and both surfaces may be irradiated when both surfaces of the substrate sandwiching the liquid crystal composition are transparent. Light irradiation may be performed at one time or may be performed by dividing into several times. So-called PSCOF (Phase Separated Composite Organic Film) (V. Vorflusev and S. Kumar, Science 283) in which the irradiance of light is distributed in the thickness direction of the liquid crystal element and the density of the polymer resin phase is continuously changed. , 1903 (1999)).

In the case of photocuring, the irradiance of light applied to the liquid crystal element is preferably 10 mW / cm ² or more. More preferably, it is 20 mW / cm ² or more, and particularly preferably 30 mW / cm ² or more. If the irradiance is too small, the polymerization does not proceed sufficiently. Even if the present invention is cured at high speed with such intense light, the liquid crystal structure is not disturbed by vigorous phase separation or a temperature rise caused by the light source or reaction heat, and the transmittance in the transparent state does not decrease. A highly transparent, colorless, and high-contrast liquid crystal element can be obtained over time.

For photocuring of the liquid crystal composition, an integrated dose of ² J / cm ² or more, preferably ³ J / cm ² or more is usually given, and the light irradiation time may be determined according to the radiation intensity of the light source. From the viewpoint of enhancing productivity, the light irradiation is usually completed within 200 seconds, preferably within 60 seconds, while it is preferable to perform light irradiation for 10 seconds or longer. If the light irradiation time is too short, the repetition durability of the liquid crystal element may be inferior. When manufacturing a sheet-like liquid crystal device with a large area using a plastic film substrate, it is possible to use a method of irradiating light continuously while moving the light source or sheet, and adjusting the moving speed according to the irradiance of the light source do it.
In the liquid crystal light control layer obtained as described above, the chiral nematic liquid crystal is dispersed or formed into a continuous layer in a thin transparent polymer, but the continuous layer exhibits the best contrast. Is formed.

<Yellowness of liquid crystal element>
The liquid crystal element of the present invention is colorless and has a feature of excellent transparency. This is due to the fact that the polymerizable group at the substituent end of the naphthalene group that is the central skeleton of the polymerizable monomer has a structure that serves as a spacer between the naphthalene group and the polymerizable group. That is, the spacer structure has high mobility of the polymerizable group, and the influence of the bulky naphthalene group, which can be sterically hindered during the reaction, is relatively small, and the monomer polymerization reaction proceeds sufficiently. It is possible to prevent the remaining element from deteriorating and adversely affecting the driving characteristics, thereby preventing the yellowing of the element.
The yellowing degree of the liquid crystal element of the present invention is an index indicating the yellowing degree of the liquid crystal element. As a measuring method, a transparent substrate of a liquid crystal element is set to an aperture portion of an integrating sphere spectrocolorimeter (SP-64 manufactured by x-rite) so that the transparent side can be measured, and tristimulus values X, Y, and Z are reflected as reflected light. After the measurement, a yellow index (YI value) is calculated. Furthermore, when the value of only the transparent substrate without a liquid crystal element is YI0, and the value of the liquid crystal element after exposure by putting the liquid crystal composition is YI1, it is represented by the following formula (1).
Yellowness = YI1-YI0 Formula (1)
The yellowing degree defined in the present invention indicates the yellowing degree derived from the liquid crystal composition regardless of the material of the substrate.

  The yellowing degree of the liquid crystal element of the present invention is preferably 4 or less, and more preferably 3 or less. The lower limit is 0, and it is preferable that the lower limit is close to 0. By being in this range, the liquid crystal element becomes colorless, and when used as a display or a screen, color reproducibility of an image or the like tends to be improved.

<Drive of liquid crystal element>
The liquid crystal element of the present invention can be switched from a transparent state to a scattering state (opaque state) by applying a voltage or returning from a voltage application state to a voltage non-application state. The liquid crystal element of the present invention is a liquid crystal element that can be used in a so-called reverse mode in which a visible light is transmitted or selectively reflected when no voltage is applied and is in a scattering state when a voltage is applied. There is a DC voltage and / or AC voltage region where the light transmittance is lower than the visible light transmittance when no voltage is applied.
In order to switch the liquid crystal element of the present invention from the transparent state to the scattering state, a voltage sufficient to cause a phase transition of the chiral nematic liquid crystal phase from the planar state to the focal conic state may be applied between the electrodes. The applied waveform is not particularly limited, such as direct current, alternating current, pulse, or a composite wave thereof. In the case of a DC voltage, preferably 0.5 msec or more, and in the case of an AC voltage, any of a sine wave, a rectangular wave, a triangular wave, or a composite wave thereof may be used, preferably a pulse wave of 0.5 msec or more at a frequency of 100 kHz or less. In this case, preferably, switching can be performed by applying a pulse width of 0.5 msec or more.
The driving voltage of the liquid crystal element is usually 60 V or less, preferably 30 V or less for a DC voltage, 120 Vp-p or less, preferably 90 Vp-p or less for an AC voltage, and a maximum value of 60 V or less for a pulse voltage. Preferably, the maximum value is 30V or less.

In addition, the haze of the liquid crystal element of the present invention is determined when no DC voltage and / or AC voltage is applied (power supply OFF
15% or less at the time), and preferably 70% or more when the DC voltage and / or AC voltage is applied (when the power is turned on). In particular, it is particularly preferable that the power is 10% or less when the power is OFF and 90% or more when the power is ON. Indoors and under fluorescent lamps, when haze exceeds 15%, cloudiness is conspicuous, and when it is less than 70%, there is a tendency that a silhouette beyond the liquid crystal element can be seen.
Further, the parallel light transmittance of the liquid crystal element of the present invention is preferably 85% or more when the power is turned off, and the power is turned on.
15% or less is preferable, 90% or more when the power is off, and 10% or less when the power is on.
If it is less than 85% indoors or under a fluorescent lamp, it is dim, and if it exceeds 15%, an object in front tends to be seen.
In the present invention, the haze and parallel light transmittance of the liquid crystal element are measured according to JIS K7105.

<Response time of liquid crystal element>
The response time described in this specification refers to visible light (380 to 800) when no voltage is applied to the liquid crystal element.
nm) Visible light when applying a test waveform (100 Hz rectangular wave in this embodiment) when the transmittance is normalized to 100%, and the visible light transmittance is reduced to 0% when voltage is applied and saturated. The time until the transmittance reaches 10% (rise response time) and the time until the visible light transmittance reaches 90% when the test waveform is not applied (fall response time) are defined. The method for measuring the response time is measured by the method described in the examples.
The response time of the liquid crystal element of the present invention is preferably 5 msec or less, more preferably 3 msec or less, for both the rising response time and the falling response time at a temperature of −10 ° C. or higher. For use as a liquid crystal element, it is preferable that the rise response time is the same as the fall response time.

  The upper limit of the operating temperature of the liquid crystal element of the present invention is Tni of the chiral nematic liquid crystal phase. However, since the response time tends to be longer at low temperatures, the operating temperature range is preferably −10 ° C. or higher, more preferably 0 ° C. That's it. Moreover, it is preferably 60 ° C. or lower, and more preferably 40 ° C. or lower.

<Applications of liquid crystal elements>
The liquid crystal composition and liquid crystal element of the present invention can be used for screens, displays and the like. For example, it can be used as a display panel or projection panel, such as a screen for blocking the visual field such as a building window, a partition and a show window, or by electrically switching the display with high-speed response. it can.
The projection system is not particularly limited, such as a front projection and a rear projection. For example, a rear projection system disclosed in Japanese Patent Laid-Open No. 6-82748 or International Publication No. 2009/150579, or Japanese Patent Laid-Open No. 2010- And a projection system using coherent light as a light source as disclosed in Japanese Patent No. 2171291.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited by a following example, unless the summary is exceeded.

<Measurement method of haze and parallel light transmittance of liquid crystal element>
The haze, parallel light transmittance and response speed of the liquid crystal element of the present invention were measured at room temperature of 25 ° C. Further, the liquid crystal was driven by applying a rectangular wave of 100 Hz, and the measurement voltage was 80 Vp-p.
Haze and parallel light transmittance were measured by a double beam method using a haze computer Hz-2 (manufactured by SUGA) and a C light source.

<Measurement method of response time of liquid crystal element>
The response speed of the liquid crystal element of the invention was measured at room temperature of 25 ° C. The liquid crystal was driven by applying a rectangular wave of 100 Hz, and the measurement voltage was measured using 80 Vp-p.
A halogen lamp was used as the light source and a photodiode was used as the detector. The rise response time and the fall response time when a test waveform (100 Hz rectangular wave) was applied while light was vertically incident on the liquid crystal element were measured.

<Measurement Method of Chiral Nematic Liquid Crystal and Liquid Crystal-Isotropic Phase Transition Temperature (Tni) of Liquid Crystal Composition>
A chiral nematic liquid crystal (liquid crystal alone or a mixture of this and a chiral agent) or a liquid crystal composition was once dissolved, and phase transition or phase separation due to temperature increase was obtained by observing with a polarizing microscope.

<Measurement Method of Dielectric Anisotropy (Δε) of Liquid Crystal> The dielectric anisotropy (Δε) of the liquid crystal was obtained by Δε = ε1-ε2. ε1 is the dielectric constant in the major axis direction of the liquid crystal molecules, and ε2 is the dielectric constant in the uniaxial direction of the liquid crystal molecules.
The dielectric constant ε (ε1 and ε2) is ε = Cd / S (C represents the capacitance of the liquid crystal. D represents the thickness of the liquid crystal layer. S represents the area of the overlapping portion of the electrodes of the two electrode substrates. It represents.

<Measurement Method of Pitch Length (p) of Chiral Nematic Liquid Crystal and Liquid Crystal Composition> The chiral nematic liquid crystal or the liquid crystal composition is injected into an empty cell having a gap of 10 μm composed of a transparent glass substrate with an electrode layer that has been subjected to a homogeneous alignment treatment. From the selective reflection wavelength λ measured by a meter, p = λ / n (where n is the refractive index of the chiral nematic liquid crystal or liquid crystal composition).

<Yellowness of liquid crystal element>
Set the transparent substrate of the liquid crystal element to the aperture part of the integrating sphere spectrocolorimeter (SP64 manufactured by x-rite) so that the transparent side can be measured, and after measuring the tristimulus values X, Y and Z from the reflected light, yellow An index (YI value) was calculated. Furthermore, when the value of only the transparent substrate without a liquid crystal element is YI0, and the value of the liquid crystal element after exposure by putting the liquid crystal composition is YI1, it is expressed by the following formula (1).
Yellowness = YI1-YI0 Formula (1)

[Example 1]
Cyano nematic liquid crystal (PDLC-005, manufactured by Hebei Luquan New Electronic Materials Co. Ltd) with Tni = 98 ° C. and Δε = 11.8 in 88.0% by mass, chiral agent (CB-15, manufactured by Merck Japan) ) Was mixed at 12.0% by mass to prepare chiral nematic liquid crystal (a). This (a) had a pitch length p = 1.2 ± 0.1 μm.
Chiral nematic liquid crystal (a) 95.0% by mass, monomer represented by the following structural formula (I) (AOE-N, manufactured by Kawasaki Kasei Co., Ltd.) 5.0% by mass, polymerization represented by the following structural formula (II) An initiator (IRGACURE184, manufactured by BASF JAPAN) 0.2 mass% was mixed, stirred and filtered to prepare a liquid crystal composition (A) having Tni = 94 ° C. This liquid crystal composition (A) was injected into an empty cell (distance (d) between substrates with electrodes = 10 μm) made of a transparent glass substrate with electrodes. This cell was kept at 20 ° C., and 60 mW / cm ² of ultraviolet light (wavelength: 330 nm) was irradiated on one side for 60 seconds with a high-pressure mercury lamp to cure the monomer to obtain a liquid crystal element (A-1).
The produced (A-1) had a transparent appearance, and showed reverse mode driving that changed to an opaque appearance when a voltage was applied. The characteristics of (A-1) are shown in Table 1.

[Example 2]
A liquid crystal device (A-2) was produced in the same manner as in Example 1 except that the amount of the polymerization initiator in Example 1 (IRGACURE184, manufactured by BASF JAPAN) was changed to 0.2% by mass.
The produced (A-2) had a transparent appearance, and showed reverse mode driving that changed to an opaque appearance when a voltage was applied. The characteristics of (A-2) are shown in Table 1.

Claims (14)

At least one is a transparent substrate, has a pair of substrates with electrodes arranged opposite to each other, and has a liquid crystal light control layer including a composite including a chiral nematic liquid crystal phase and a polymer resin phase between the substrates A liquid crystal element, wherein the polymer resin phase contains a polymer compound having a polymer represented by the following general formula (1), and the dielectric anisotropy of the chiral nematic liquid crystal phase is positive .

[In general formula (1),
X ¹⁰⁰ represents an alkylene group which may have a substituent, an aromatic hydrocarbon group which may have a substituent or an aromatic heterocyclic group which may have a substituent,
R ¹⁰⁰ represents a hydrogen atom or an alkyl group which may have a substituent,
y represents an integer of 1 or more, and two or more X ¹⁰⁰ present in one molecule of the polymer represented by the general formula (1) may be the same or different,
z represents an integer of 1 to 3, and when z is 2 or more, two or more X ¹⁰¹ present in one molecule of the polymer represented by the general formula (1) may be the same or different. ¹⁰¹ represents a group represented by the following general formula (2),

In general formula (2), ^X102 represents a direct bond or one linking group selected from the following group,

X ¹⁰³ represents a direct bond or one linking group selected from the following group:

R ¹⁰¹ represents a hydrogen atom, a halogen atom, a hydroxyl group, a linear or branched alkyl group having 1 to 7 carbon atoms, a linear or branched alkoxy group having 1 to 7 carbon atoms, or a cyano group. Represent,
z ′ represents an integer of 1 to 3, and when z ′ is 2 or more, two or more of —X ¹⁰² —X ¹⁰³ — present in one molecule of the polymer represented by the general formula (1) are the same. May be different. ) The liquid crystal device according to claim 1, wherein the chiral nematic liquid crystal contains a compound having a cyano group. 3. The liquid crystal device according to claim 1, wherein a chiral pitch length p of the chiral nematic liquid crystal is 0.3 μm or more and 3 μm or less. 4. The liquid crystal element according to claim 1, wherein there is a region of direct current voltage and / or alternating current voltage in which the visible light transmittance when a voltage is applied is lower than the visible light transmittance when no voltage is applied. 5. The distance d between the substrates with electrodes is 100 μm ≧ d ≧ 2 μm, and the relationship between the chiral pitch lengths p and d of the chiral nematic liquid crystal is d / p ≧ 1. The liquid crystal element described in 1. The liquid crystal element according to any one of claims 1 to 5, wherein a haze when applying at least one of a DC voltage and an AC voltage is 70% or more and a haze when no voltage is applied is 15% or less. In the temperature range of −10 ° C. or higher, the visible light transmittance without application of at least one of the DC voltage and AC voltage of the liquid crystal element is reduced to 100%, and the minimum is reduced by applying at least one of the DC voltage and AC voltage. When the visible light transmittance is normalized to 0%, the time from when at least one of DC voltage and AC voltage is applied until the visible light transmittance becomes 10%, and the DC voltage and AC voltage 7. The liquid crystal device according to claim 1, wherein the time from when at least one of them is not applied until the visible light transmittance reaches 90% is 8 msec or less, respectively. The liquid crystal element according to any one of claims 1 to 7, wherein the yellowing degree of the liquid crystal element is 4 or less. A screen comprising the liquid crystal element according to claim 1. Display having a liquid crystal device according to any one of claims 1-8. A liquid crystal composition comprising a chiral nematic liquid crystal having a positive dielectric anisotropy and a polymerizable monomer represented by the following general formula (3).

[In general formula (3),
X ¹ represents an alkylene group which may have a substituent, an aromatic hydrocarbon group which may have a substituent or an aromatic heterocyclic group which may have a substituent,
R ¹ represents a hydrogen atom or an alkyl group which may have a substituent,
n represents an integer of 1 or more, and X ¹ present in two or more polymerizable monomers represented by the general formula (3) may be the same or different,
m represents an integer of 1 to 3, and when m is 2 or more, two or more X ² present in one molecule of the polymerizable monomer represented by the general formula (3) may be the same or different. , X ² represents a group represented by the following general formula (4),

In general formula (4), X ¹⁰ represents a direct bond or one linking group selected from the following group:

X ¹¹ represents a direct bond or one linking group selected from the following group:

R ¹⁰ represents a hydrogen atom, a halogen atom, a hydroxyl group, a linear or branched alkyl group having 1 to 7 carbon atoms, a linear or branched alkoxy group having 1 to 7 carbon atoms, or a cyano group. Represent,
w represents an integer of 1 to 3, and when w is 2 or more, two or more -X ¹⁰ -X ^11- present in one molecule of the polymerizable monomer represented by the general formula (3) are the same. May be different. The liquid crystal composition according to claim 11, wherein the chiral nematic liquid crystal contains a compound having a cyano group. 13. The liquid crystal composition according to claim 11, wherein a chiral pitch length p of the chiral nematic liquid crystal is 0.3 μm or more and 3 μm or less. The liquid crystal composition according to claim 11, wherein the liquid crystal-isotropic phase transition temperature is 40 ° C. or higher.