JP7226428B2 - liquid crystal display element - Google Patents

Description

The present invention relates to a transmission scattering liquid crystal display element.

A TN (Twisted Nematic) mode has been put into practical use as a liquid crystal display element. In this mode, it is necessary to use a polarizing plate in order to switch light using the optical rotatory property of the liquid crystal. The use of a polarizing plate lowers the light utilization efficiency.
As a liquid crystal display element that does not use a polarizing plate, there is an element that switches liquid crystal between a transmissive state (also referred to as a transparent state) and a scattering state. In general, liquid crystals using polymer-dispersed liquid crystal (PDLC) or polymer network liquid crystal (PNLC) are known.

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

In a liquid crystal display element using PDLC or PNLC, when no voltage is applied, the liquid crystal is oriented in random directions, resulting in a cloudy (scattering) state. There is a liquid crystal display element that becomes a transmissive state as a result (also called 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 electrodes and the liquid crystal layer (the composite of the liquid crystal and the cured product of the polymerizable compound) are in direct contact (see Patent Documents 1 and 2).
On the other hand, a liquid crystal display element (also referred to as a reverse type element) using PDLC, which is in a transmissive state when no voltage is applied and is in a scattering state when a voltage is applied, has also been proposed (see Patent Documents 3 and 4).

Japanese Patent No. 3552328 Japanese Patent No. 4630954 Japanese Patent No. 2885116 Japanese Patent No. 4132424

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 adhesion between the liquid crystal layer and the electrode. However, since inorganic electrodes such as ITO (Indium Tin Oxide) are generally used in liquid crystal display elements, compatibility with polymerizable compounds of organic substances, that is, adhesion tends to be low. When the adhesion is low, long-term use, especially in harsh environments such as high temperature, high humidity, and exposure to light, causes peeling of the element, generation of air bubbles, and deterioration of the optical properties of the scattering state and the transparent state. more likely to cause decline.

From the above points, the present invention enhances the adhesion between the liquid crystal layer and the electrode, and prevents the peeling of the element, the generation of air bubbles, and the optical An object of the present invention is to provide a liquid crystal display device capable of suppressing deterioration of characteristics.

As a result of intensive studies to achieve the above object, the inventors have completed the present invention having the following gist.
That is, the present invention has a liquid crystal layer in which a liquid crystal composition containing a liquid crystal and a polymerizable compound disposed between a pair of substrates provided with electrodes is cured by irradiating with ultraviolet rays, and a scattering state occurs when no voltage is applied. In the liquid crystal display element, which becomes transparent when a voltage is applied, the liquid crystal composition contains a compound represented by the following formula [1].

(X ¹ represents the following formula [1-a] or formula [1-b]. X ² represents an alkylene group having 2 to 24 carbon atoms, and X ¹ and O of the alkylene group are any arbitrary -CH ₂ - may be substituted with -O-, -CO-, -COO-, -OCO-, -CONH-, -NHCO-, -NH- or -CON(CH ₃ )- Xm is represents an integer of 1 or 2. Xn represents an integer of 1 or 2. However, Xm+Xn is 3.)

According to the present invention, the adhesion between the liquid crystal layer and the electrodes is increased, and even in a harsh environment where the liquid crystal layer and the electrodes are exposed to high temperature, high humidity, and light irradiation for a long time, the element peels off, bubbles are generated, and optical characteristics are deteriorated. It is possible to obtain a liquid crystal display element which can suppress the scattering and which is in a scattering state when no voltage is applied and is in a transparent state when a voltage is applied. Therefore, the element of the present invention can be used for a liquid crystal display intended for display, a dimming window for controlling the blocking and transmission of light, an optical shutter element, and the like.

The mechanism by which the liquid crystal display device having the above-described excellent characteristics can be obtained by the present invention is not necessarily clear, but is presumed to be as follows.
The liquid crystal composition used in the present invention contains a liquid crystal, a polymerizable compound, and a compound represented by formula [1] (also referred to as a specific compound). The specific compound has a site that undergoes a polymerization reaction with ultraviolet rays, represented by ^X1 in formula [1], and a phosphate group. Therefore, when the specific compound is included in the liquid crystal composition, the interaction between the phosphoric acid group and the inorganic electrode such as the ITO electrode works, and the site of X1 in the formula [1] reacts with the polymerizable compound. As a result, it is considered that the adhesion between the polymer network in the liquid crystal layer and the electrodes is enhanced.

From the above points, the liquid crystal display element using the liquid crystal composition of the present invention improves the adhesion between the liquid crystal layer and the electrode, and can It becomes a liquid crystal display element capable of suppressing peeling of the element, generation of air bubbles, and deterioration of optical properties. In particular, it can be suitably used for a normal type element that becomes a scattering state when no voltage is applied and a transparent state when a voltage is applied.

<Liquid crystal composition>
The liquid crystal composition in the invention contains a liquid crystal, a polymerizable compound, and the specific compound represented by the above formula [1].
Nematic liquid crystal, smectic liquid crystal, or cholesteric liquid crystal can be used for the liquid crystal. Among them, liquid crystals having positive dielectric anisotropy are preferable for normal type devices, and liquid crystals having negative dielectric anisotropy are preferably used for reverse type devices. In this case, from the viewpoint of low-voltage driving and scattering characteristics, it is preferable that the anisotropy of the dielectric constant is large and the anisotropy of the refractive index is large. In addition, two or more kinds of liquid crystals can be mixed and used for the liquid crystal according to the physical property values of the phase transition temperature, dielectric anisotropy, and refractive index anisotropy.

In order to drive a liquid crystal display element as an active element such as a TFT (Thin Film Transistor), the liquid crystal is required to have a high electric resistance and a high voltage holding ratio (also called VHR). Therefore, it is preferable to use a fluorine-based or chlorine-based liquid crystal, which has a high electrical resistance and does not lower the VHR due to active energy rays such as ultraviolet rays, as the liquid crystal.

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

The polymerizable compound in the liquid crystal composition is for forming a polymer network (also referred to as a curable resin) through a polymerization reaction when irradiated with ultraviolet rays during the production of the 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 made into a polymer, it must have a site that undergoes a polymerization reaction when irradiated with ultraviolet rays. As the polymerizable compound, it is preferable to use a liquid crystal composition containing a polymerizable compound from the viewpoint of handling of the liquid crystal composition, that is, suppression of increase in viscosity of the liquid crystal composition and solubility in liquid crystal.
The polymerizable compound is not particularly limited as long as it dissolves in the liquid crystal, but when the polymerizable compound is dissolved in the liquid crystal, it is necessary that there is a temperature at which part or all of the liquid crystal composition exhibits a liquid crystal phase. Even if a part of the liquid crystal composition exhibits a liquid crystal phase, it is sufficient if the liquid crystal display element is observed with the naked eye and substantially uniform transparency and scattering properties are obtained throughout the element.

Any polymerizable compound may be used as long as it is polymerized by ultraviolet rays, and in that case, the polymerization proceeds in any reaction form to form a curable resin. Specific reaction forms include radical polymerization, cationic polymerization, anionic polymerization, and polyaddition reaction.
Among them, the reaction form of the polymerizable compound is preferably radical polymerization from the viewpoint of the optical properties of the liquid crystal display device. At that time, as the polymerizable compound, the following radical-type polymerizable compound or an oligomer thereof can be used. Moreover, as described above, polymers obtained by polymerizing these polymerizable compounds can also be used.
Specific examples of radical type polymerizable compounds or oligomers thereof include radical type polymerizable compounds described on pages 69 to 71 of International Publication No. WO2015/146987.

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 and the electrode of the liquid crystal display element. . More preferably, it is 80 to 110 parts by mass. In addition, the radical type polymerizable compound may be used alone or in combination of two or more depending on the properties.
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 preferred. Specific examples include radical initiators described on pages 71-72 of International Publication No. 2015/146987.

The ratio of the radical initiator to be 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 from the viewpoint of adhesion between the liquid crystal layer and the electrodes of the liquid crystal display element. More preferably, it is 0.05 to 10 parts by mass. Also, the radical initiator can be used alone or in combination of two or more depending on the properties.

<Specific compound>
The specific compound is a compound represented by the above formula [1].
In formula [1], X ¹ , X ² , Xm and Xn are as defined above.
X ¹ is preferably the above formula [1-a] or formula [1-b]. X ² is preferably an alkylene group having 2 to 12 carbon atoms, and any —CH ₂ — not adjacent to X ¹ and O may be substituted with —O—, —COO— or —OCO—. Xm is preferably an integer of 1 or 2. Xn is preferably an integer of 1 or 2. However, Xm+Xn is 3.

Specific specific compounds include compounds selected from the group consisting of the following formulas [1a-1] to [1a-3], and these are preferably used.

X ^a represents the formula [1-a] or formula [1-b]. X ^b represents an alkylene group having 2 to 18 carbon atoms. ^Xc represents -COO- or -OCO-.
X ^d represents an alkylene group having 2 to 12 carbon atoms. p1 represents an integer of 1 or 2; p2 represents an integer of 1 or 2; However, p1+p2 is 3. p3 represents an integer of 2-8.

More specifically, Phosmer-M, Phosmer-PE, Phosmer-PP (manufactured by DAP), Light Acrylate P-1A (N), Light Ester P-1M (manufactured by Kyoeisha Chemical Co., Ltd.), KAYAMER PM -2 and KAYAMER PM-21 (manufactured by Nippon Kayaku Co., Ltd.).
The content of the specific compound is preferably 0.01 to 20 parts by mass, preferably 0.05 to 0.05 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 and the electrode of the liquid crystal display element. 10 parts by weight is more preferred, and 0.1 to 10 parts by weight is most preferred. Also, the specific compound can be used alone or in combination of two or more depending on the properties.

<Second specific compound>
The liquid crystal composition of the invention preferably contains a compound represented by the following formula [2] (also referred to as a second specific compound).

Y ¹ represents the following formulas [2-a] to [2-j]. Among them, formula [2-a], formula [2-b], formula [2-c], formula [2-d], formula [2-e] or formula [2-f] is preferable. Formula [2-a], Formula [2-b], Formula [2-c] or Formula [2-e] is more preferred, and Formula [2-a] or Formula [2-b] is most preferred.

Y ^A represents a hydrogen atom or a benzene ring.
Y ² is a single bond, -O-, -NH-, -N(CH ₃ )-, -CH ₂ O-, -CONH-, -NHCO-, -CON(CH ₃ )-, -N(CH ₃ ) represents CO-, -COO- or -OCO-. Among them, a single bond, -O-, -CH ₂ O-, -CONH-, -COO- or -OCO- is preferable, and a single bond, -O-, -COO- or -OCO- is more preferable.

Y ³ represents a single bond or -(CH ₂ ) _a - (a is an integer of 1 to 15). Among them, a single bond or —(CH ₂ ) _a — (a is an integer of 1 to 10) is preferred, and —(CH ₂ ) _a — (a is an integer of 1 to 10) is particularly preferred.
Y ⁴ represents a single bond, -O-, -OCH ₂ -, -COO- or -OCO-. Among them, a single bond, -O- or -COO- is preferred, and -O- is particularly preferred.

Y ⁵ represents a divalent cyclic group selected from a benzene ring, a cyclohexane ring and a heterocyclic ring, or a divalent organic group having 17 to 51 carbon atoms and having a steroid skeleton, and any hydrogen atom on the cyclic group is It may be substituted with 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 a fluorine atom. Among them, a benzene ring, a cyclohexane ring, or a divalent organic group having 17 to 51 carbon atoms having a steroid skeleton is preferable. More preferred is a C17-51 divalent organic group having a benzene ring or a steroid skeleton.

Y ⁶ represents a single bond, -O-, -CH ₂ -, -OCH ₂ -, -CH ₂ O-, -COO- or -OCO-. Among them, a single bond, -O-, -COO- or -OCO- is preferable, and a single bond, -COO- or -OCO- is more preferable.
Y ⁷ represents a cyclic group selected from a benzene ring, a cyclohexane ring and a heterocyclic ring, and any hydrogen atom on these cyclic groups is an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a carbon It may be substituted with 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. Among them, a benzene ring or a cyclohexane ring is preferable.

Y 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 a fluorine-containing alkoxy group having 1 to 18 carbon atoms. indicates a group. Among them, an alkyl group or alkoxy group having 1 to 18 carbon atoms, or an alkenyl group having 2 to 18 carbon atoms is preferable. More preferred are alkyl groups or alkoxy groups having 1 to 12 carbon atoms.
Ym represents an integer of 0-4. Among them, an integer of 0 to 2 is preferable.
Preferred combinations of Y ¹ to Y ⁸ and Ym in formula [2] are shown in Tables 1 to 9 below. In Tables 1 to 9, a in —(CH ₂ )— representing Y ³ represents an integer of 1 to 10.

Among them, (2-3a) ~ (2-8a), (2-11a) ~ (2-24a), (2-27a) ~ (2-36a), (2-39a), (2-40a) , (2-43a) ~ (2-48a), (2-51a) ~ (2-64a), (2-67a) ~ (2-76a), (2-79a), (2-80a), ( 2-83a) ~ (2-88a), (2-91a) ~ (2-104a), (2-107a) ~ (2-116a), (2-119a), (2-120a), (2- 123a), (2-124a), (2-129a), (2-130a), (2-133a), (2-134a), (2-137a), (2-138a), (2-141a) , (2-142a), (2-145a), (2-146a) or combinations of (2-149a) to (2-172a) are preferred.

More preferably, (2-3a) ~ (2-8a), (2-11a), (2-12a), (2-15a) ~ (2-18a), (2-21a), (2- 22a), (2-27a) to (2-30a), (2-33a), (2-34a), (2-39a), (2-40a), (2-43a) to (2-48a) , (2-51a), (2-52a), (2-55a) ~ (2-58a), (2-61a), (2-62a), (2-67a) ~ (2-70a), ( 2-73a), (2-74a), (2-79a), (2-80a), (2-83a) ~ (2-88a), (2-91a), (2-92a), (2- 95a) ~ (2-98a), (2-101a), (2-102a), (2-107a) ~ (2-110a), (2-113a), (2-114a), (2-119a) , (2-120a), (2-123a), (2-124a), (2-129a), (2-130a), (2-133a), (2-134a), (2-137a), ( 2-138a), (2-141a), (2-142a), (2-145a), (2-146a) or a combination of (2-149a) to (2-172a).

Most preferred are (2-3a) to (2-8a), (2-15a) to (2-18a), (2-29a), (2-30a), (2-43a) to (2- 48a), (2-55a) to (2-58a), (2-69a), (2-70a), (2-83a) to (2-88a), (2-95a) to (2-98a) , (2-109a), (2-110a), (2-123a), (2-124a), (2-133a), (2-134a), (2-141a), (2-142a), ( 2-149a) to (2-152a) or combinations of (2-161a) to (2-172a).

More specific second specific compounds include compounds selected from the group consisting of the following formulas [2a-1] to [2a-11], and these are preferably used.

In the above formula, Y ^a represents -O- or -COO-. ^Yb represents an alkyl group having 1 to 12 carbon atoms. q1 represents an integer of 1-10. q2 represents an integer of 1 or 2;

In formulas [2a-5] to [2a-8], ^Yc represents a single bond, -COO- or -OCO-. Y ^d represents an alkyl or alkoxy group having 1 to 12 carbon atoms. q3 represents an integer of 1-10. q4 represents an integer of 1 or 2;

In formulas [2a-9] to [2a-11], Y ^e represents -O- or -COO-. Y ^f represents a divalent organic group having 17 to 51 carbon atoms and having a steroid skeleton. Y ^g represents an alkyl group having 1 to 12 carbon atoms or an alkenyl group having 2 to 18 carbon atoms. q5 represents an integer of 1-10.

The content ratio of the second specific compound is preferably 0.1 to 30 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 and the electrode of the liquid crystal display element. .5 to 20 parts by weight is more preferred, and 1 to 10 parts by weight is most preferred. Also, the second specific compound can be used alone or in combination of two or more depending on the properties.

Examples of the method for preparing the liquid crystal composition include a method of mixing the liquid crystal, the polymerizable compound, and the specific compound together, and a method of mixing the liquid crystal with a mixture of the polymerizable compound and the specific compound in advance. . Among them, a method of mixing a liquid crystal with a mixture of a polymerizable compound and a specific compound in advance is preferable.
In addition, the second specific compound is added to the liquid crystal in which the polymerizable compound and the specific compound are mixed, or the liquid crystal is prepared in advance by adding the second specific compound, and the polymerizable compound and the specific compound are added thereto. A method of adding to the mixture is mentioned.
When preparing the liquid crystal composition as described above, heating may be performed depending on the solubility of the polymerizable compound, the specific compound, and the second specific compound. The temperature at that time is preferably less than 100°C.

<Method for producing 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 the glass substrate, an acrylic substrate, a polycarbonate substrate, a plastic substrate such as a PET (polyethylene terephthalate) substrate, and films thereof. can be used. In particular, a plastic substrate or film is preferable when used for a light control window or the like. From the viewpoint of process simplification, a substrate having an ITO electrode, an IZO (Indium Zinc Oxide) electrode, an IGZO (Indium Gallium Zinc Oxide) electrode, an organic conductive film, or the like for driving liquid crystal is preferable. In the case of a reflective liquid crystal display element, a silicon wafer, a substrate on which a metal such as aluminum or a dielectric multilayer film is formed can be used as long as the substrate is only on one side.

In the case of a reverse type liquid crystal display element, it is preferable to attach a liquid crystal alignment film to at least one of the substrates so as to vertically align liquid crystal molecules. This liquid crystal aligning film is produced by applying a liquid crystal aligning agent onto a substrate and baking it. At that time, an orientation treatment such as rubbing treatment or light irradiation may be performed after baking.
The liquid crystal composition used for the liquid crystal display element is as described above, and a spacer for controlling the electrode gap (also referred to as gap) of the liquid crystal display element can be introduced thereinto.

The method of injecting the liquid crystal composition is not particularly limited, but includes, for example, the following method. That is, when glass substrates are used as the substrates, a pair of substrates are prepared, four pieces of one substrate are coated with a sealing agent except for a part, and then the electrode surface is turned inside, and the other substrate is coated with a sealant. An empty cell is produced by pasting the substrates together. Then, there is a method of obtaining a liquid crystal composition-injected cell by injecting the liquid crystal composition under reduced pressure from a place where the sealant is not applied. Furthermore, when a plastic substrate or film is used as the substrate, a pair of substrates are prepared, and the liquid crystal composition is dropped onto one of the substrates by an ODF (One Drop Filling) method, an inkjet method, or the like. A method of obtaining a liquid crystal composition-injected cell by laminating the substrates on one side is 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 aforementioned spacer or the like. Examples of the method include, as described above, 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 a desired size, and the like. Further, when a plastic or film substrate is used for the substrate and the substrates are attached by lamination, the gap can be controlled without introducing a spacer.

The gap size 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 will be lowered, and if it is too large, the driving voltage of the element will be high.

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

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to these. The abbreviations used below are as follows.
<Specific compound>
X1: Phosmer-PE (manufactured by DAP)
X2: KAYAMER PM-21 (manufactured by Nippon Kayaku Co., Ltd.)

<Second 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 Allnex)
R5: EBECRYL 4858 (manufactured by Daicel Allnex)
R6: Karenz MT PE1 (manufactured by Showa Denko)

<Photoradical initiator>
P1: IRGACURE 184 (manufactured by BASF)
<LCD>
L1: MLC-3018 (manufactured by Merck)

<Production of liquid crystal composition (1)>
Mix R1 (1.35 g), R2 (0.20 g), R3 (1.00 g), R4 (0.80 g), R5 (0.20 g) and R6 (0.30 g) and heat at 60° C. for 2 hours. Stirred. After that, X1 (0.05 g) was added to prepare a polymerizable compound solution. A solution of a 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 (1).

<Production of liquid crystal composition (2)>
Mix R1 (1.30 g), R2 (0.20 g), R3 (1.00 g), R4 (0.80 g), R5 (0.20 g) and R6 (0.30 g) and heat at 60° C. for 2 hours. Stirred. After that, X2 (0.10 g) was added to prepare a polymerizable compound solution. A solution of a 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 (2).

<Production of liquid crystal composition (3)>
Mix R1 (1.40 g), R2 (0.20 g), R3 (1.00 g), R4 (0.80 g), R5 (0.20 g) and R6 (0.30 g) and heat at 60° C. for 2 hours. Stirred. After that, X2 (0.10 g) was added to prepare a polymerizable compound solution. Meanwhile, 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 the second specific compound. A solution of a polymerizable compound, a liquid crystal containing the second specific compound, and P1 (0.10 g) were mixed and stirred at 25° C. for 6 hours to obtain a liquid crystal composition (3).

<Production of liquid crystal composition (4)>
Mix R1 (1.20 g), R2 (0.20 g), R3 (1.00 g), R4 (0.80 g), R5 (0.20 g) and R6 (0.30 g) and heat at 60° C. for 2 hours. Stirred. After that, X2 (0.20 g) was added to prepare a polymerizable compound solution. Meanwhile, S1 (0.20 g), S2 (0.20 g) and L1 (5.60 g) were mixed and stirred at 25° C. for 2 hours to prepare a liquid crystal containing the second specific compound. A solution of a polymerizable compound, a liquid crystal containing the second specific compound, and P1 (0.10 g) were mixed and stirred at 25° C. for 6 hours to obtain a liquid crystal composition (4).

<Production of liquid crystal composition (5)>
Mix R1 (1.40 g), R2 (0.20 g), R3 (1.00 g), R4 (0.80 g), R5 (0.20 g) and R6 (0.30 g) and heat at 60° C. for 2 hours. A solution of the polymerizable compound was prepared by stirring. A solution of a 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).

"Fabrication 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. A 15 μm spacer (trade name: Micropearl, manufactured by Sekisui Chemical Co., Ltd.) was applied. After that, the above liquid crystal compositions (1) to (5) are dropped onto the spacer-coated surface of the substrate by the ODF (One Drop Filling) method, and then the other substrate is attached so that the ITO surface faces each other. They were combined to obtain a liquid crystal display element before treatment.
The liquid crystal display element before this treatment was irradiated with ultraviolet rays for 60 seconds using a metal halide lamp with an illuminance of 20 mW/cm ² to cut wavelengths of 350 nm or less. Thus, a liquid crystal display element (glass substrate) was obtained.

"Fabrication 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 15 μm spacer was applied to the ITO surface of one of the substrates. Thereafter, the above liquid crystal compositions (1) to (5) are dropped by the ODF method on the ITO surface of the substrate coated with the spacer, and then the other substrate is laminated so that the ITO surface faces each other, A liquid crystal display element before treatment was obtained. Note that a glass substrate was used as a support substrate for the PET substrate with the ITO electrodes when the liquid crystal composition was dropped and bonded by the ODF method. After that, the supporting substrate was removed before irradiation with ultraviolet light.
The liquid crystal display element before this treatment was irradiated with ultraviolet rays in the same manner as in the above-mentioned "Preparation of liquid crystal display element (glass substrate)" to obtain a liquid crystal display element (plastic substrate).

"Evaluation of optical properties (scattering properties and transparency)"
This evaluation was carried out by measuring the haze (cloudiness) of the liquid crystal display element (glass substrate and plastic substrate) with no voltage applied (0 V) and with voltage applied (AC drive: 10 V to 50 V). 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, the higher the haze in the non-voltage-applied state, the better the scattering properties, and the lower the haze in the voltage-applied state, the better the transparency.

In addition, as a stability test of the liquid crystal display element under a high-temperature and high-humidity environment, measurement was also performed after storage for 24 hours in a constant temperature and humidity chamber at a temperature of 80° C. and a humidity of 90% RH. Specifically, the smaller the change in haze after storage in the constant temperature and humidity chamber with respect to the initial haze, the better this evaluation.
Furthermore, as a stability test of the liquid crystal display element against light irradiation, observation was also made after irradiation with ultraviolet rays of 5 J/cm ² at a wavelength of 365 nm using a desktop UV curing device (HCT3B28HEX-1, manufactured by Senlight Co., Ltd.). gone. Specifically, the smaller the change in haze after UV irradiation with respect to the initial haze, the better the evaluation.
Table 10 summarizes the haze measurement results at the initial stage, after storage in a constant temperature and humidity bath (constant temperature and humidity), and after ultraviolet irradiation (ultraviolet rays).

"Evaluation of Adhesion between Liquid Crystal Layer and Electrode"
In this evaluation, the liquid crystal display element (glass substrate and plastic substrate) was stored in a constant temperature and humidity chamber at a temperature of 80°C and a humidity of 90% RH for 24 hours, and the peeling of the liquid crystal display element and the presence or absence of air bubbles were confirmed. (as a stability test of the liquid crystal display element under high temperature and high humidity environment). Specifically, those that do not have peeling of the element (a state in which the liquid crystal layer and the resin film or the resin film and the electrode are peeled off) and those that do not generate air bubbles in the element are excellent in this evaluation. (good display in the table).

In addition, confirmation was also performed after irradiating the liquid crystal display element with ultraviolet rays of 5 J/cm ² at a wavelength of 365 nm using a desktop UV curing device (HCT3B28HEX-1, Senlight Co., Ltd.) (the light of the liquid crystal display element as a stability test against irradiation of Specifically, those in which no delamination of the element occurred and those in which no air bubbles were generated in the element were judged to be excellent in this evaluation (good indication in the table).
Table 11 summarizes the results (adhesion) between the liquid crystal layer and the electrode at the initial stage, after storage in a constant temperature and humidity bath (constant temperature and humidity), and after ultraviolet irradiation (ultraviolet rays).

<Examples 1 to 8 and Comparative Examples 1 and 2>
As shown in Tables 10 and 11 below, the liquid crystal compositions (1) to (5) were used to prepare liquid crystal display elements according to the methods described above, and the optical properties (scattering properties and transparency) were evaluated. , and the adhesion between the liquid crystal layer and the electrodes were evaluated.
At that time, in Examples 1, 3, 5, 7 and Comparative Example 1, a glass substrate was used to fabricate and evaluate the liquid crystal display element, and in Examples 2, 4, 6, 8 and Comparative Example 2, plastic A substrate was used.

＊１：素子内に少量の気泡が見られた。
＊２：素子内に気泡が見られた（＊１よりも多い）。

*1: A small amount of air bubbles were observed in the element.
*2: Air bubbles were observed in the element (more than *1).

As can be seen from Tables 10 and 11, the liquid crystal display elements of Examples had better optical properties than Comparative Examples, that is, the haze after storage in a constant temperature and humidity chamber and after UV irradiation compared to the initial stage. change is smaller. Furthermore, the liquid crystal display element has high adhesion between the liquid crystal layer and the electrodes, and no peeling or air bubbles were observed in the liquid crystal display element even after being exposed to these severe environments. In particular, even when a plastic substrate was used as the substrate of the liquid crystal display element, these characteristics were excellent. Specifically, comparisons between Examples 1 and 3 and Comparative Example 1 and between Examples 2 and 4 and Comparative Example 2 are made under the same conditions.
Also, when the second specific compound was introduced into the liquid crystal composition, the haze was lowered at a lower voltage. Specifically, in the comparison under the same conditions, the comparison between Example 3 and Example 5 and the comparison between Example 4 and Example 6 are performed.

The liquid crystal display element of the present invention can be suitably used as a normal type element which becomes a scattering state when no voltage is applied and becomes a transparent state when a voltage is applied. This element can be used for a liquid crystal display for display purposes, and furthermore, for a light control window or an optical shutter element for controlling the blocking and transmission of light. A substrate can be used.

In addition, the entire contents of the specification, claims, drawings, and abstract of Japanese Patent Application No. 2018-052661 filed on March 20, 2018 are cited here as disclosure of the specification of the present invention. , is to be incorporated.

Claims (7)

It has a liquid crystal layer that is cured by irradiating a liquid crystal composition containing a liquid crystal and a polymerizable compound placed between a pair of substrates with electrodes and by irradiating it with ultraviolet rays. A liquid crystal display element, wherein the liquid crystal composition contains a compound represented by the following formula [1a-2] or [1a-3] .

(X ^a represents the following formula [1-a] or formula [1-b]. X ^b represents an alkylene group having 2 to 18 carbon atoms. X ^c represents -COO- or -OCO- X ^d represents an alkylene group having 2 to 12 carbon atoms, p1 represents an integer of 1 or 2, p2 represents an integer of 1 or 2, provided that p1+p2 is 3, p3 is 2 to indicates an integer of 8.)

The liquid crystal display element according to claim 1, wherein the content of the compound represented by formula [1a-2] or formula [1a-3] is 0.05 to 10 parts by mass with respect to 100 parts by mass of the liquid crystal. . 3. The liquid crystal display element according to claim 1 , wherein the liquid crystal composition contains a compound represented by the following formula [2].

(Y ¹ represents the following formulas [2-a] to [2-j]. Y ² is a single bond, -O-, -NH-, -N(CH ₃ )-, -CH ₂ O-, - CONH-, -NHCO-, -CON(CH ₃ )-, -N(CH ₃ )CO-, -COO- or -OCO- ^{Y 3} is a single bond or -(CH ₂ ) _a - (a is is an integer of 1 to 15) Y ⁴ represents a single bond, —O—, —OCH ₂ —, —COO— or —OCO— Y ⁵ represents a group consisting of a benzene ring, a cyclohexane ring and a heterocyclic ring or a divalent organic group having 17 to 51 carbon atoms having a steroid skeleton, wherein any hydrogen atom on the cyclic group is an alkyl group having 1 to 3 carbon atoms, an alkyl group having 1 to 3 carbon atoms, may be substituted with 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 a fluorine atom, Y ⁶ is a single bond, —O—, — CH ₂ —, —OCH ₂ —, —CH ₂ O—, —COO— or —OCO— Y ⁷ represents a cyclic group selected from the group consisting of a benzene ring, a cyclohexane ring and a heterocyclic ring, and these cyclic Any hydrogen atom on the group is 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 Y 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 represents a fluorine-containing alkoxy group having 1 to 18 carbon atoms, and Ym represents an integer of 0 to 4.)

(Y ^A represents a hydrogen atom or a benzene ring.) 4. The liquid crystal display element according to claim 3 , wherein the content of the compound represented by the formula [2] is 0.5 to 20 parts by mass with respect to 100 parts by mass of the liquid crystal. 5. The liquid crystal display element according to claim 3 , wherein the compound represented by formula [2] is at least one selected from the group consisting of formulas [2a-1] to [2a-11] below.

(Y ^a represents -O- or -COO-. Y ^b represents an alkyl group having 1 to 12 carbon atoms. q1 represents an integer of 1 to 10. q2 represents an integer of 1 or 2. show.)

(Y ^c represents a single bond, -COO- or -OCO-. Y ^d represents an alkyl group or alkoxy group having 1 to 12 carbon atoms. q3 represents an integer of 1 to 10. q4 is Indicates an integer of 1 or 2.)

(Y ^e represents -O- or -COO-. ^{Y f} represents a divalent organic group having 17 to 51 carbon atoms and a steroid skeleton. ^{Y g} represents an alkyl group having 1 to 12 carbon atoms or represents an alkenyl group having 2 to 18 carbon atoms, and q5 represents an integer of 1 to 10.) 6. The liquid crystal display element according to claim 1 , wherein the substrate of said 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 6 , wherein the liquid crystal display element is a light control window or an optical shutter element.