JPWO2019181883A1 - Liquid crystal display element - Google Patents

Abstract

Provided is a liquid crystal display element which exhibits good optical characteristics and lowers the driving voltage of the liquid crystal display element. A liquid crystal composition containing a liquid crystal and a polymerizable compound arranged between a pair of substrates provided with electrodes has a liquid crystal layer cured by irradiating ultraviolet rays, and is in a scattered state when no voltage is applied and is transparent when a voltage is applied. A liquid crystal display element in a state, wherein the liquid crystal has positive dielectric anisotropy, and the liquid crystal composition contains a compound represented by the following formula [1]. .. [Chemical formula 1] (Definition of each symbol in the formula is as described in the specification.)

Description

The present invention relates to a transmission-scattering type liquid crystal display element that is in a transmission state when a voltage is applied.

As a liquid crystal display element, a TN (Twisted Nematic) mode has been put into practical use. In this mode, it is necessary to use a polarizing plate in order to switch light by utilizing the optical rotation characteristic of the liquid crystal. When a polarizing plate is used, the efficiency of light utilization is lowered.
As a liquid crystal display element that does not use a polarizing plate, there is an element that switches between a transmissive state (also referred to as a transparent state) and a scattering state of a liquid crystal. Generally, those using a polymer dispersed liquid crystal (also referred to as PDLC (Polymer Dispersed Liquid Crystal)) or a polymer network type liquid crystal (also referred to as PNLC (Polymer Network Liquid Crystal)) are known.

In these liquid crystal display elements, a liquid crystal composition containing a polymerizable compound that is polymerized by ultraviolet rays is arranged between a pair of substrates provided with electrodes, and the liquid crystal composition is cured by irradiation with ultraviolet rays to be polymerizable with the liquid crystal. It forms a complex with a cured product of the compound (eg, a polymer network). Then, in this liquid crystal display element, the scattering state and the transmission state of the liquid crystal are controlled by applying a voltage.

A liquid crystal display element using PDLC or PNLC is in a cloudy (scattered) state because the liquid crystal is oriented in a random direction when no voltage is applied, and when a voltage is applied, the liquid crystals are arranged in the electric field direction and transmit light. (Also referred to as a normal type element). In this case, since the liquid crystal is random when no voltage is applied, there is no need for a liquid crystal alignment film or alignment treatment for aligning the liquid crystal in one direction. Therefore, in this liquid crystal display element, the electrode and the liquid crystal layer (composite of the liquid crystal and the cured product of the polymerizable compound) are in direct contact with each other (see Patent Documents 1 and 2).

Japanese Patent No. 3552328 Japanese Patent No. 4630954

The polymerizable compound in the liquid crystal composition has a role of forming a polymer network to obtain desired optical properties and a role of enhancing the adhesion between the liquid crystal layer and the electrode. However, in order to realize these, it is necessary to form a dense polymer network, so that the driving of the liquid crystal molecules with respect to the voltage application is hindered. for that reason. The drive voltage of this element is higher than that of a liquid crystal display element such as TN mode.
From the above points, it is an object of the present invention to provide a liquid crystal display element which exhibits good optical characteristics and lowers the driving voltage of the liquid crystal display element.

（Ｘ^１は下記式［１−ａ］〜式［１−ｊ］を示す。Ｘ^２は単結合、−Ｏ−、−ＮＨ−、−Ｎ（ＣＨ_３）−、−ＣＨ_２Ｏ−、−ＣＯＮＨ−、−ＮＨＣＯ−、−ＣＯＮ（ＣＨ_３）−、−Ｎ（ＣＨ_３）ＣＯ−、−ＣＯＯ−又は−ＯＣＯ−を示す。Ｘ^３は単結合又は−（ＣＨ_２）_ａ−（ａは１〜１５の整数である）を示す。Ｘ^４は単結合、−Ｏ−、−ＯＣＨ_２−、−ＣＯＯ−又は−ＯＣＯ−を示す。Ｘ^５はベンゼン環、シクロヘキサン環及び複素環からなる群から選ばれる２価の環状基、又はステロイド骨格を有する炭素数１７〜５１の２価の有機基を示し、前記環状基上の任意の水素原子は、炭素数１〜３のアルキル基、炭素数１〜３のアルコキシ基、炭素数１〜３のフッ素含有アルキル基、炭素数１〜３のフッ素含有アルコキシ基又はフッ素原子で置換されていてもよい。Ｘ^６は単結合、−Ｏ−、−ＣＨ_２−、−ＯＣＨ_２−、−ＣＨ_２Ｏ−、−ＣＯＯ−又は−ＯＣＯ−を示す。Ｘ^７はベンゼン環、シクロヘキサン環及び複素環からなる群から選ばれる環状基を示し、これらの環状基上の任意の水素原子が、炭素数１〜３のアルキル基、炭素数１〜３のアルコキシ基、炭素数１〜３のフッ素含有アルキル基、炭素数１〜３のフッ素含有アルコキシ基又はフッ素原子で置換されていてもよい。Ｘ^８は炭素数１〜１８のアルキル基、炭素数２〜１８のアルケニル基、炭素数１〜１８のフッ素含有アルキル基、炭素数１〜１８のアルコキシ基又は炭素数１〜１８のフッ素含有アルコキシ基を示す。Ｘｍは０〜４の整数を示す。）

（Ｘ^Ａは水素原子又はベンゼン環を示す。）As a result of diligent research to achieve the above object, the present inventor has completed the present invention having the following gist.
That is, the present invention has a liquid crystal layer containing a liquid crystal and a polymerizable compound arranged between a pair of substrates provided with electrodes and cured by irradiating the liquid crystal with ultraviolet rays, and is in a scattered state when no voltage is applied. The liquid crystal display element becomes transparent when a voltage is applied, the liquid crystal has positive dielectric anisotropy, and the liquid crystal composition contains a compound represented by the following formula [1]. It is in a liquid crystal display element characterized by.

(X ¹ represents the following formulas [1-a] to [1-j]. X ² is a single bond, -O-, -NH-, -N (CH ₃ )-, -CH ₂ O-,-. It indicates CONH-, -NHCO-, -CON (CH ₃ )-, -N (CH ₃ ) CO-, -COO- or -OCO-. X ³ is a single bond _{or-(CH 2} ) _a- (a is. X ⁴ represents a single bond, -O-, -OCH _2- , -COO- or -OCO-. X ⁵ is a group consisting of a benzene ring, a cyclohexane ring and a heterocycle. A divalent cyclic group selected from the above, or a divalent organic group having a steroid skeleton and having 17 to 51 carbon atoms, and any hydrogen atom on the cyclic group has an alkyl group having 1 to 3 carbon atoms and a carbon number of carbon atoms. It may be substituted with an alkoxy group of 1 to 3, a fluorine-containing alkyl group having 1 to 3 carbon atoms, a fluorine-containing alkoxy group having 1 to 3 carbon atoms, or a fluorine atom. X ⁶ is a single bond, −O−, −. CH _2- , -OCH _2- , -CH ₂ O-, -COO- or -OCO-. X ⁷ represents a cyclic group selected from the group consisting of a benzene ring, a cyclohexane ring and a heterocycle, and these cyclic groups. Any hydrogen atom on the group can be an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a fluorine-containing alkyl group having 1 to 3 carbon atoms, a fluorine-containing alkoxy group having 1 to 3 carbon atoms, or fluorine. It may be substituted with an atom. X ⁸ is an alkyl group having 1 to 18 carbon atoms, an alkenyl group having 2 to 18 carbon atoms, a fluorine-containing alkyl group having 1 to 18 carbon atoms, an alkoxy group having 1 to 18 carbon atoms, or an alkoxy group having 1 to 18 carbon atoms. Indicates a fluorine-containing alkoxy group having 1 to 18 carbon atoms. Xm indicates an integer of 0 to 4.)

(X ^A indicates a hydrogen atom or a benzene ring.)

According to the present invention, it is possible to obtain a liquid crystal display element having good optical characteristics and a low driving voltage of the liquid crystal display element. Therefore, the element of the present invention is used in a liquid crystal display for display as a normal type element, a dimming window for controlling transmission and blocking of light, an optical shutter element, and the like.
The mechanism by which the liquid crystal display element having the above-mentioned excellent characteristics can be obtained by the present invention is not necessarily clear, but it is presumed as follows.

The liquid crystal composition used in the present invention contains a liquid crystal having positive dielectric anisotropy, a polymerizable compound, and a compound represented by the above formula [1] (also referred to as a specific compound). Certain compounds have a site of rigid structure such as a benzene ring or a cyclohexane ring, and a portion of the polymerization reaction by ultraviolet rays represented by X ¹ in the formula [1]. Therefore, when such a specific compound is included in the liquid crystal composition, the portion of the rigid structure of the specific compound enhances the vertical orientation of the liquid crystal, promotes the drive of the liquid crystal when a voltage is applied, and lowers the drive voltage of the liquid crystal display element. it can. Further, since the sites of X ¹ in the formula [1] is reacted with a polymerizable compound, it is possible to maintain the polymer network dense state.
From the above points, the liquid crystal display element using the liquid crystal composition in the present invention is a normal type element having good optical characteristics and a low driving voltage of the liquid crystal display element.

<Liquid crystal composition>
The liquid crystal composition in the present invention contains a liquid crystal, a polymerizable compound, and a specific compound represented by the above formula [1].
As the liquid crystal, a nematic liquid crystal, a smectic liquid crystal or a cholesteric liquid crystal can be used. Above all, in the present invention, it is preferable to have positive dielectric anisotropy. Further, from the viewpoint of low voltage drive and scattering characteristics, it is preferable that the dielectric constant has a large anisotropy and the refractive index has a large anisotropy. Further, as the liquid crystal, two or more kinds of liquid crystals can be mixed and used according to the respective physical property values of the phase transition temperature, the dielectric anisotropy and the refractive index anisotropy.

In order to drive a liquid crystal display element as an active element such as a TFT (Thin Film Transistor), it is required that the electric resistance of the liquid crystal is high and the voltage retention rate (also referred to as VHR) is high. Therefore, it is preferable to use a fluorine-based or chlorine-based liquid crystal having high electrical resistance and whose VHR is not lowered by active energy rays such as ultraviolet rays.

Further, the liquid crystal display element can be made into a guest host type element by dissolving a dichroic dye in the liquid crystal composition. In this case, an element that absorbs (scatters) when no voltage is applied and becomes transparent when a voltage is applied can be obtained. Further, in this liquid crystal display element, the direction (direction of orientation) of the director of the liquid crystal changes by 90 degrees depending on the presence or absence of voltage application. Therefore, this liquid crystal display element can obtain higher contrast than the conventional guest-host type element that switches between random orientation and vertical orientation by utilizing the difference in absorption characteristics of the dichroic dye. Further, in the guest host type device in which the dichroic dye is dissolved, the liquid crystal becomes colored when it is oriented in the horizontal direction and becomes opaque only in the scattered state. Therefore, as the voltage is applied, it is possible to obtain an element that switches from the colored opacity when no voltage is applied to the colored transparent and colorless transparent states.

The polymerizable compound in the liquid crystal composition is for forming a curable resin by a polymerization reaction by irradiation with ultraviolet rays at the time of producing a liquid crystal display element. Therefore, a polymer obtained by polymerizing a polymerizable compound in advance may be introduced into the liquid crystal composition. However, even if it is a polymer, it is necessary to have a site that undergoes a polymerization reaction by irradiation with ultraviolet rays. As the polymerizable compound, it is preferable to use a liquid crystal composition containing the polymerizable compound from the viewpoint of handling the liquid crystal composition, that is, suppressing the increase in viscosity of the liquid crystal composition and the solubility in the liquid crystal.
The polymerizable compound is not particularly limited as long as it is dissolved in the liquid crystal, but it is necessary that a part or the whole of the liquid crystal composition has a temperature at which the liquid crystal phase is exhibited when the polymerizable compound is dissolved in the liquid crystal. Even when a part of the liquid crystal composition exhibits a liquid crystal phase, it is sufficient that the liquid crystal display element is visually confirmed and the entire inside of the element is obtained with substantially uniform scattering characteristics and transparency.

The polymerizable compound may be any compound that is polymerized by ultraviolet rays, and at that time, the polymerization may proceed in any reaction form to form a curable resin. Specific reaction types include radical polymerization, cationic polymerization, anionic polymerization and polyaddition reaction.
Among them, the reaction type of the polymerizable compound is preferably radical polymerization from the viewpoint of the optical characteristics of the liquid crystal display element. At that time, as the polymerizable compound, the following radical-type polymerizable compound or an oligomer thereof can be used. Further, as described above, a polymer obtained by polymerizing these polymerizable compounds can also be used.
Specific examples of the radical-type polymerizable compound or its oligomer include the radical-type polymerizable compound described on pages 69 to 71 of International Publication No. 2015/146987 (Published on 2015.10.1).

The ratio of the radical type polymerizable compound or its oligomer used is preferably 70 to 150 parts by mass with respect to 100 parts by mass of the liquid crystal in the liquid crystal composition from the viewpoint of adhesion between the liquid crystal layer of the liquid crystal display element and the electrode. , 80 to 110 parts by mass is more preferable. Further, the radical type polymerizable compound may be used alone or in combination of two or more depending on each property.
In order to promote the formation of the curable resin, a radical initiator (also referred to as a polymerization initiator) that generates radicals by ultraviolet rays is introduced into the liquid crystal composition for the purpose of promoting radical polymerization of the polymerizable compound. Is preferable.
Specific examples thereof include radical initiators described on pages 71 to 72 of International Publication No. 2015/146987.

The ratio of the radical initiator used is preferably 0.01 to 20 parts by mass with respect to 100 parts by mass of the liquid crystal in the liquid crystal composition, preferably 0.05, from the viewpoint of adhesion between the liquid crystal layer of the liquid crystal display element and the electrode. 10 parts by mass is more preferable. Further, the radical initiator may be used alone or in combination of two or more, depending on each property.
The specific compound is a compound represented by the above formula [1].

Wherein ^[1], X 1 ~X ⁸ and Xm is as defined above, among others respectively, preferably from below.
X ¹ is the formula [1-a], Formula [1-b] of the formula [1-c] of the formula [1-d], formula [1-e] or formula [1-f] are preferred, wherein [ 1-a], formula [1-b], formula [1-c] or formula [1-e] are more preferable, and formula [1-a] or formula [1-b] is most preferable.
X ² is preferably single-bonded, -O-, -CH ₂ O-, -CONH-, -COO- or -OCO-, and more preferably single-bonded, -O-, -COO- or -OCO-.

X ³ is preferably a single bond or − (CH ₂ ) _a − (a is an integer of 1 to 10), and more preferably − (CH ₂ ) _a − (a is an integer of 1 to 10).
X ⁴ is preferably single-bonded, -O- or -COO-, more preferably -O-.
X ⁵ is preferably a divalent organic group having 17 to 51 carbon atoms having a benzene ring or a cyclohexane ring, or steroid skeleton, a divalent organic group having 17 to 51 carbon atoms having a benzene ring or a steroid skeleton is more preferable.
X ⁶ is preferably single-bonded, -O-, -COO- or -OCO-, more preferably single-bonded, -COO- or -OCO-.

X ⁷ is preferably a benzene ring or a cyclohexane ring.
X ⁸ is preferably an alkyl group or an alkoxy group having 1 to 18 carbon atoms or an alkenyl group having 2 to 18 carbon atoms, and more preferably an alkyl group or an alkoxy group having 1 to 12 carbon atoms. Xm is preferably an integer of 0 to 2.

A preferred combination of ^X 1 to X ⁸ and Xm in formula [1] are shown in Table 1-9 below.

Among them, (1-3a) to (1-8a), (1-11a) to (1-24a), (1-27a) to (1-36a), (1-39a), (1-40a). , (1-43a) to (1-48a), (1-51a) to (1-64a), (1-67a) to (1-76a), (1-79a), (1-80a), ( 1-83a) to (1-88a), (1-91a) to (1-104a), (1-107a) to (1-116a), (1-119a), (1-120a), (1- 123a), (1-124a), (1-129a), (1-130a), (1-133a), (1-134a), (1-137a), (1-138a), (1-141a). , (1-142a), (1-145a), (1-146a) or combinations of (1-149a) to (1-172a) are preferred.

More preferred are (1-3a) to (1-8a), (1-11a), (1-12a), (1-15a) to (1-18a), (1-21a), (1- 22a), (1-27a) to (1-30a), (1-33a), (1-34a), (1-39a), (1-40a), (1-43a) to (1-48a). , (1-51a), (1-52a), (1-55a) to (1-58a), (1-61a), (1-62a), (1-67a) to (1-70a), ( 1-73a), (1-74a), (1-79a), (1-80a), (1-83a) to (1-88a), (1-91a), (1-92a), (1- 95a) to (1-98a), (1-101a), (1-102a), (1-107a) to (1-110a), (1-113a), (1-114a), (1-119a). , (1-120a), (1-123a), (1-124a), (1-129a), (1-130a), (1-133a), (1-134a), (1-137a), ( 1-138a), (1-141a), (1-142a), (1-145a), (1-146a) or a combination of (1-149a) to (1-172a).

Most preferred are (1-3a) to (1-8a), (1-15a) to (1-18a), (1-29a), (1-30a), (1-43a) to (1-). 48a), (1-55a) to (1-58a), (1-69a), (1-70a), (1-83a) to (1-88a), (1-95a) to (1-98a). , (1-109a), (1-110a), (1-123a), (1-124a), (1-133a), (1-134a), (1-141a), (1-142a), ( It is a combination of 1-149a) to (1-152a) or (1-161a) to (1-172a).

（Ｘ^ａは、−Ｏ−又は−ＣＯＯ−を示す。Ｘ^ｂは、炭素数１〜１２のアルキル基を示す。ｐ１は、１〜１０の整数を示す。ｐ２は、１又は２の整数を示す。）More specific specific compounds include compounds selected from the group consisting of the following formulas [1a-1] to [1a-11], and it is preferable to use these.

(X ^a represents -O- or -COO-. X ^b represents an alkyl group having 1 to 12 carbon atoms. P1 represents an integer of 1 to 10. P2 represents an integer of 1 or 2. Show.)

（Ｘ^ｃは、単結合、−ＣＯＯ−又は−ＯＣＯ−を示す。Ｘ^ｄは、炭素数１〜１２のアルキル基又はアルコキシ基を示す。ｐ３は、１〜１０の整数を示す。ｐ４は、１又は２の整数を示す。）

(X ^c represents a single bond, -COO- or -OCO-. X ^d represents an alkyl group or an alkoxy group having 1 to 12 carbon atoms. P3 represents an integer of 1 to 10. P4 represents an integer of 1 to 10. Indicates an integer of 1 or 2.)

（Ｘ^ｅは、−Ｏ−又は−ＣＯＯ−を示す。Ｘ^ｆは、ステロイド骨格を有する炭素数１７〜５１の２価の有機基を示す。Ｘ^ｇは、炭素数１〜１２のアルキル基又は炭素数２〜１８のアルケニル基を示す。ｐ５は、１〜１０の整数を示す。）

(X ^e represents -O- or -COO-. X ^f represents a divalent organic group having a steroid skeleton and having 17 to 51 carbon atoms. X ^g represents an alkyl group having 1 to 12 carbon atoms or an alkyl group having 1 to 12 carbon atoms. Indicates an alkenyl group having 2 to 18 carbon atoms. P5 represents an integer of 1 to 10).

The content ratio of the specific compound is preferably 0.1 to 30 parts by mass, preferably 0.5 to 30 parts by mass, based on 100 parts by mass of the liquid crystal in the liquid crystal composition, from the viewpoint of adhesion between the liquid crystal layer of the liquid crystal display element and the electrode. 20 parts by mass is more preferable, and 1 to 10 parts by mass is most preferable. Further, the specific compound may be used alone or in combination of two or more depending on each property.

As a method for preparing the liquid crystal composition, a method of adding a single or a mixture of a plurality of kinds of polymerizable compounds and a specific compound to the liquid crystal, or a method of preparing a liquid crystal to which a specific compound is added in advance and then singly or a plurality of kinds thereof. A method of adding the polymerizable compound of the above can be mentioned.
When a plurality of types of polymerizable compounds are used, they can be heated depending on the solubility of the polymerizable compounds when they are mixed. The temperature at that time is preferably less than 100 ° C. The same applies to the case where the polymerizable compound and the specific compound are mixed, and the case where the liquid crystal and the specific compound are mixed.

<Method of manufacturing liquid crystal display element>
The substrate used for the liquid crystal display element is not particularly limited as long as it is a highly transparent substrate, and in addition to a glass substrate, a plastic substrate such as an acrylic substrate, a polycarbonate substrate, a PET (polyethylene terephthalate) substrate, and a film thereof. Can be used. In particular, when used for a dimming window or the like, a plastic substrate or film is preferable. From the viewpoint of process simplification, it is preferable to use a substrate on which an ITO electrode for driving a liquid crystal, an IZO (Indium Zinc Oxide) electrode, an IGZO (Indium Gallium Zinc Oxide) electrode, an organic conductive film, or the like is formed. .. Further, in the case of a reflective liquid crystal display element, if only one substrate is used, a substrate on which a metal such as a silicon wafer or aluminum or a dielectric multilayer film is formed can be used.

The liquid crystal composition used for the liquid crystal display element is the liquid crystal composition as described above, but a spacer for controlling the electrode gap (also referred to as a gap) of the liquid crystal display element can be introduced therein.
The method for injecting the liquid crystal composition is not particularly limited, and examples thereof include the following methods. That is, when a glass substrate is used as the substrate, a pair of substrates is prepared, and four pieces of the substrate on one side are coated with a sealant except for a part, and then the electrode surface is on the inside so that the other side is on the other side. An empty cell is prepared by laminating the substrates. Then, a method of injecting the liquid crystal composition under reduced pressure from a place where the sealant is not applied to obtain a liquid crystal composition injection cell can be mentioned. Furthermore, when using a plastic substrate or film as the substrate, prepare a pair of substrates, drop the liquid crystal composition onto one of the substrates by the ODF (One Drop Filling) method, the inkjet method, or the like, and then drop the liquid crystal composition onto the substrate. A method of sticking the substrates on one side to obtain a liquid crystal composition injection cell can be mentioned. In the liquid crystal display element of the present invention, since the adhesion between the liquid crystal layer and the electrodes is high, it is not necessary to apply a sealant to the four pieces of the substrate.

The gap of the liquid crystal display element can be controlled by the spacer or the like. Examples of the method include a method of introducing a spacer of a desired size into the liquid crystal composition, a method of using a substrate having a column spacer of the desired size, and the like. Further, when a plastic or film substrate is used as the substrate and the substrates are laminated by lamination, the gap can be controlled without introducing a spacer.
The size of the gap of the liquid crystal display element is preferably 1 to 100 μm, more preferably 1 to 50 μm, and particularly preferably 2 to 30 μm. If the gap is too small, the contrast of the liquid crystal display element decreases, and if it is too large, the drive voltage of the element increases.

The liquid crystal display element is obtained by curing the liquid crystal composition to form a liquid crystal layer. The liquid crystal composition is cured by irradiating the liquid crystal composition injection cell with ultraviolet rays. Examples of the light source of the ultraviolet irradiation device used at that time include a metal halide lamp and a high-pressure mercury lamp. At that time, the wavelength of ultraviolet rays is preferably 250 to 400 nm, more preferably 310 to 370 nm. Moreover, you may perform heat treatment after irradiating with ultraviolet rays. The temperature at that time is preferably 20 to 120 ° C, more preferably 30 to 100 ° C.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto. The abbreviations used below are as follows.
<Specific compound>

<Polymerizable compound>
R1: IBXA (manufactured by Osaka Organic Chemical Industry Co., Ltd.)
R2: 2-Hydroxyethyl methacrylate R3: KAYARAD FM-400 (manufactured by Nippon Kayaku Co., Ltd.)
R4: EBECRYL 230 (manufactured by Daicel Ornex)
R5: Calends MT PE1 (manufactured by Showa Denko)
<Photoradical initiator>
P1: IRGACURE 184 (manufactured by BASF)
<LCD>
L1: MLC-3018 (manufactured by Merck & Co., Ltd.)

<Preparation of liquid crystal composition (1)>
R1 (1.20 g), R2 (0.30 g), R3 (1.20 g), R4 (0.90 g) and R5 (0.30 g) are mixed and stirred at 60 ° C. for 2 hours to obtain a polymerizable compound. The solution of was prepared. On the other hand, S1 (0.20 g) and L1 (5.80 g) were mixed and stirred at 25 ° C. for 2 hours to prepare a liquid crystal containing a specific compound. Then, the prepared solution of the polymerizable compound, the liquid crystal containing the specific compound, and P1 (0.10 g) were mixed and stirred at 25 ° C. for 6 hours to obtain a liquid crystal composition (1).

<Preparation of liquid crystal composition (2)>
R1 (1.20 g), R2 (0.30 g), R3 (1.20 g), R4 (0.90 g) and R5 (0.30 g) are mixed and stirred at 60 ° C. for 2 hours to obtain a polymerizable compound. The solution of was prepared. On the other hand, S1 (0.80 g) and L1 (5.20 g) were mixed and stirred at 25 ° C. for 2 hours to prepare a liquid crystal containing a specific compound. Then, the prepared solution of the polymerizable compound, the liquid crystal containing the specific compound, and P1 (0.10 g) were mixed and stirred at 25 ° C. for 6 hours to obtain a liquid crystal composition (2).

<Preparation of liquid crystal composition (3)>
R1 (1.20 g), R2 (0.30 g), R3 (1.20 g), R4 (0.90 g) and R5 (0.30 g) are mixed and stirred at 60 ° C. for 2 hours to obtain a polymerizable compound. The solution of was prepared. On the other hand, S2 (0.40 g) and L1 (5.60 g) were mixed and stirred at 25 ° C. for 2 hours to prepare a liquid crystal containing a specific compound. Then, the prepared solution of the polymerizable compound, the liquid crystal containing the specific compound, and P1 (0.10 g) were mixed and stirred at 25 ° C. for 6 hours to obtain a liquid crystal composition (3).

<Preparation of liquid crystal composition (4)>
R1 (1.20 g), R2 (0.30 g), R3 (1.20 g), R4 (0.90 g) and R5 (0.30 g) are mixed and stirred at 60 ° C. for 2 hours to obtain a polymerizable compound. The solution of was prepared. On the other hand, S1 (0.20 g), S2 (0.10 g) and L1 (5.70 g) were mixed and stirred at 25 ° C. for 2 hours to prepare a liquid crystal containing a specific compound. Then, the prepared solution of the polymerizable compound, the liquid crystal containing the specific compound, and P1 (0.10 g) were mixed and stirred at 25 ° C. for 6 hours to obtain a liquid crystal composition (4).

<Preparation of liquid crystal composition (5)>
R1 (1.20 g), R2 (0.30 g), R3 (1.20 g), R4 (0.90 g) and R5 (0.30 g) are mixed and stirred at 60 ° C. for 2 hours to obtain a polymerizable compound. The solution of was prepared. Then, the prepared solution of the polymerizable compound, L1 (6.00 g) and P1 (0.10 g) were mixed and stirred at 25 ° C. for 6 hours to obtain a liquid crystal composition (5).

"Manufacturing of liquid crystal display element (glass substrate)"
Two glass substrates with ITO electrodes (length: 100 mm, width: 100 mm, thickness: 0.7 mm) washed with pure water and IPA (isopropyl alcohol) were prepared, and the particle size was measured on the ITO surface of one of the substrates. A 15 μm spacer (trade name: Micropearl, manufactured by Sekisui Chemical Co., Ltd.) was applied. Then, the liquid crystal compositions (1) to (5) are dropped onto the surface of the substrate coated with the spacer by the ODF (One Drop Filling) method, and then the liquid crystal compositions (1) to (5) are attached so that the ITO surfaces of the other substrate face each other. The alignment was performed to obtain a liquid crystal display element before processing.
^{A metal halide lamp having an illuminance of 20 mW / cm 2} was used for the liquid crystal display element before this treatment to cut wavelengths of 350 nm or less, and ultraviolet irradiation was performed with an irradiation time of 60 seconds. As a result, a liquid crystal display element (glass substrate) was obtained.

"Manufacturing of liquid crystal display element (plastic substrate)"
Two PET substrates with ITO electrodes (length: 150 mm, width: 150 mm, thickness: 0.1 mm) washed with pure water were prepared, and the 20 μm spacer was applied to the ITO surface of one of the substrates. Then, the liquid crystal compositions (1) to (5) are dropped onto the ITO surface coated with the spacer of the substrate by the ODF method, and then bonded so that the ITO surfaces of the other substrate face each other. A liquid crystal display element before processing was obtained. When the liquid crystal composition was dropped and bonded by the ODF method, a glass substrate was used as a support substrate for the PET substrate with an ITO electrode. Then, the support substrate was removed before irradiating with ultraviolet rays.
The liquid crystal display element before this treatment was irradiated with ultraviolet rays by the same method as in the above-mentioned "Production of liquid crystal display element (glass substrate)" to obtain a liquid crystal display element (plastic substrate).

"Evaluation of optical characteristics (scattering characteristics and transparency)"
This evaluation was performed by measuring the haze (cloudiness) of the liquid crystal display element (glass substrate and plastic substrate) in the voltage-free state (0V) and the voltage-applied state (AC drive: 10V to 50V). At that time, Haze was measured with a haze meter (HZ-V3, manufactured by Suga Test Instruments Co., Ltd.) in accordance with JIS K 7136. In this evaluation, it was determined that the higher the haze in the no-voltage state, the better the scattering characteristics, and the lower the haze in the voltage-applied state, the better the transparency. The results of Haze are summarized in Table 10.

<Examples 1 to 8 and Comparative Examples 1 and 2>
As shown in Table 10 below, using the liquid crystal compositions (1) to (5), the liquid crystal display element was manufactured and the optical characteristics (scattering characteristics and transparency) were evaluated by the above method. ..
At that time, in Example 1, Example 3, Example 5, Example 7, and Comparative Example 1, a liquid crystal display element was manufactured using a glass substrate and each evaluation was performed, and Examples 2, Example 4, and Example 1 were carried out. 6. In Example 8 and Comparative Example 2, a plastic substrate was used.

As can be seen from Table 10 above, the liquid crystal display element of the example has a lower Haze in the voltage-applied state and a lower Haze at a lower voltage than the comparative example. That is, in the embodiment, good optical characteristics (transparency) are exhibited, and the driving voltage of the liquid crystal display element is low.
Specifically, it is clear from the comparison between Example 1 and Comparative Example 1, and the comparison between Example 2 and Comparative Example 2, which are comparisons under the same conditions. These results were the same even when a plastic substrate was used as the substrate of the liquid crystal display element.

Further, the liquid crystal display element of the present invention can be suitably used for a normal type element which is in a scattered state when no voltage is applied and is in a transparent state when a voltage is applied. This element can be used for a liquid crystal display for display purposes, a dimming window for controlling light blocking and transmission, an optical shutter element, and the like, and the substrate of this normal type element is made of plastic. A substrate can be used.
The entire contents of the specification, claims, drawings, and abstract of Japanese Patent Application No. 2018-052662 filed on March 20, 2018 are cited here as disclosure of the specification of the present invention. , Incorporate.

Claims (6)

A liquid crystal composition containing a liquid crystal and a polymerizable compound arranged between a pair of substrates provided with electrodes has a liquid crystal layer cured by irradiating with ultraviolet rays, and is in a scattered state when no voltage is applied and transparent when a voltage is applied. A liquid crystal display element that is in a state
The liquid crystal has positive dielectric anisotropy and
A liquid crystal display device, wherein the liquid crystal composition contains a compound represented by the following formula [1].

(X ¹ represents the following formulas [1-a] to [1-j]. X ² is a single bond, -O-, -NH-, -N (CH ₃ )-, -CH ₂ O-,-. It indicates CONH-, -NHCO-, -CON (CH ₃ )-, -N (CH ₃ ) CO-, -COO- or -OCO-. X ³ is a single bond _{or-(CH 2} ) _a- (a is. X ⁴ represents a single bond, -O-, -OCH _2- , -COO- or -OCO-. X ⁵ is a group consisting of a benzene ring, a cyclohexane ring and a heterocycle. A divalent cyclic group selected from the above, or a divalent organic group having a steroid skeleton and having 17 to 51 carbon atoms, and any hydrogen atom on the cyclic group has an alkyl group having 1 to 3 carbon atoms and a carbon number of carbon atoms. It may be substituted with an alkoxy group of 1 to 3, a fluorine-containing alkyl group having 1 to 3 carbon atoms, a fluorine-containing alkoxy group having 1 to 3 carbon atoms, or a fluorine atom. X ⁶ is a single bond, −O−, −. CH _2- , -OCH _2- , -CH ₂ O-, -COO- or -OCO-. X ⁷ represents a cyclic group selected from the group consisting of a benzene ring, a cyclohexane ring and a heterocycle, and these cyclic groups. Any hydrogen atom on the group can be an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a fluorine-containing alkyl group having 1 to 3 carbon atoms, a fluorine-containing alkoxy group having 1 to 3 carbon atoms, or fluorine. It may be substituted with an atom. X ⁸ is an alkyl group having 1 to 18 carbon atoms, an alkenyl group having 2 to 18 carbon atoms, a fluorine-containing alkyl group having 1 to 18 carbon atoms, an alkoxy group having 1 to 18 carbon atoms, or an alkoxy group having 1 to 18 carbon atoms. Indicates a fluorine-containing alkoxy group having 1 to 18 carbon atoms. Xm indicates an integer of 0 to 4.)

(X ^A indicates a hydrogen atom or a benzene ring.) The liquid crystal display element according to claim 1, wherein the amount of the compound represented by the formula [1] introduced is 0.5 to 20 parts by mass with respect to 100 parts by mass of the liquid crystal. ^{X 1} in the formula [1] is the formula [1-a], the formula [1-b], the formula [1-c], the formula [1-d], the formula [1-e] or the formula [1]. -F] The liquid crystal display element according to claim 1 or 2. The liquid crystal display device according to claim 1 or 2, wherein the compound represented by the formula [1] is at least one selected from the group consisting of the following formulas [1a-1] to [1a-11].

(X ^a represents -O- or -COO-. X ^b represents an alkyl group having 1 to 12 carbon atoms. P1 represents an integer of 1 to 10. P2 represents an integer of 1 or 2. Show.)

(X ^c represents a single bond, -COO- or -OCO-. X ^d represents an alkyl group or an alkoxy group having 1 to 12 carbon atoms. P3 represents an integer of 1 to 10. P4 represents an integer of 1 to 10. Indicates an integer of 1 or 2.)

(X ^e represents -O- or -COO-. X ^f represents a divalent organic group having a steroid skeleton and having 17 to 51 carbon atoms. X ^g represents an alkyl group having 1 to 12 carbon atoms or an alkyl group having 1 to 12 carbon atoms. Indicates an alkenyl group having 2 to 18 carbon atoms. P5 represents an integer of 1 to 10). The liquid crystal display element according to any one of claims 1 to 4, wherein the substrate of the liquid crystal display element is a glass substrate or a plastic substrate. The liquid crystal display element according to any one of claims 1 to 5, wherein the liquid crystal display element is a dimming window or an optical shutter element.