KR102238101B1 - Smectic liquid crystal compound and Polarizing plate - Google Patents

Abstract

The present application relates to a smectic liquid crystal compound and a use of the smectic liquid crystal compound. The present application may provide a smectic liquid crystal compound having excellent horizontal alignment on a single alignment layer. When the Smectic liquid crystal compound is applied to a polarizing plate, a polarizing plate having an excellent dichroic ratio may be provided. The polarizing plate may be applied to various optical elements such as a display device.

Description

Smectic liquid crystal compound and polarizing plate

The present application relates to a smectic liquid crystal compound and a polarizing plate.

Using existing nematic liquid crystals, a film with a high dichroic ratio could not be made. However, it has been reported that it can have a high dichroic ratio by using a smectic liquid crystal. However, the above result is a result of injecting a Smectic liquid crystal between two alignment layers, and there is a problem in that the Smectic liquid crystal is not horizontally aligned but is vertically aligned on a single alignment layer. When the Smectic liquid crystal is vertically aligned, a high dichroic ratio cannot be expected, and a problem in that alignment is deteriorated occurs. Therefore, there is a need for a technique of horizontally aligning Smectic liquid crystals on a single alignment layer.

An object of the present application is to provide a smectic liquid crystal compound having excellent horizontal alignment on a single alignment layer and a use of the smectic liquid crystal compound.

The present application relates to a smectic liquid crystal compound. The Smectic liquid crystal compound of the present application may have excellent horizontal alignment even on a single alignment layer by having a structure unique to the present application.

In the present specification, the smectic liquid crystal phase refers to a liquid crystal phase in which a director of a liquid crystal compound is aligned in a predetermined direction while the liquid crystal compound forms a layer or a plane. In the present specification, when the liquid crystal compound is in a rod shape, the director of the liquid crystal compound may mean a long axis direction of the rod, and when the liquid crystal compound is in a disk shape, it may mean a normal direction of the disk.

The smectic liquid crystal compound of the present application may be represented by the following formula (1).

[Formula 1]

In Formula 1, A and A'are independently of each other -CH ₂ -, -O-, or -S-,

B and B'are independently of each other -COO- or -OCO-,

C is a phenylene group, a cyclohexeylene group, or a naphthylene group,

D and D'are independently of each other a hydrocarbon group having 4 to 12 carbon atoms,

E is a polymerizable functional group,

F is -OH, -CN, -NH ₂ or -NO ₂ .

The Smectic liquid crystal compound of Formula 1 may have excellent horizontal alignment even on a single alignment layer by introducing a polar functional group instead of the _{-CH 3} terminal, which is known to have low surface energy.

In Formula 1, A and A'may each be -O-.

In Formula 1, B and B'may each be -COO-.

In Formula 1, C may be a phenylene group.

In Formula 1, D and D'may each be an alkylene group having 6 carbon atoms.

In Formula 1, it may be an E (meth) acrylate group.

In Formula 1, F may be -CN.

The present application relates to the use of the smectic liquid crystal compound. The present application relates to a polarizing plate including the smectic liquid crystal compound. The polarizing plate of the present application may include a polarizing layer and an alignment layer under the polarizing layer.

The polarizing layer may include a smectic liquid crystal compound and an anisotropic dye. The polarizing plate including the polarizing layer may be referred to as a guest host type polarizing plate. In the present application, the guest host polarizing plate is a device in which anisotropic dyes (guests) are arranged together according to the arrangement of liquid crystals (hosts), and each exhibits anisotropic light absorption characteristics with respect to the alignment direction of the anisotropic dye and the direction perpendicular to the alignment direction. Can mean For example, anisotropic dyes are materials whose absorption rate of light varies depending on the polarization direction.If the absorption rate of light polarized in the long axis direction is large, it is called a p-type dye, and when the absorption rate of light polarized in the minor axis direction is large, it is called n-type dye. can do. In one example, when a p-type dye is used, polarized light vibrating in the long axis direction of the dye is absorbed, and polarized light vibrating in the short axis direction of the dye is less absorbed and thus can be transmitted.

Since the Smectic liquid crystal compound of the present application may have excellent horizontal alignment even on a single alignment layer, when applied to a guest host type polarizing plate, a polarizing plate having excellent dichroic ratio may be provided.

The smectic liquid crystal compound may exist in a horizontally aligned state in the polarizing layer. In the present specification, the horizontal alignment state is a state in which the directors of all liquid crystal molecules are arranged in parallel with the plane of the liquid crystal layer, for example, 0 degrees to 5 degrees, 0 degrees to 4 degrees, 0 degrees to 3 degrees, 0 degrees to 2 degrees, 0 degrees to 1 degrees, preferably, may mean an arrangement of 0 degrees.

The smectic liquid crystal compound may exist in a polymerized state in a polarizing layer. In the present application, that the liquid crystal is included in a polymerized state may mean a state in which the liquid crystal compound is polymerized by a polymerizable group to form a skeleton such as a main chain or a side chain of a liquid crystal polymer.

In the present specification, the term ``dye'' may refer to a material capable of intensively absorbing and/or modifying light in at least a part or the entire range in a visible light region, for example, 400 nm to 700 nm wavelength range, The term "anisotropic dye" may mean a material capable of anisotropic absorption of light in at least a part or the entire range of the visible light region.

As the anisotropic dye, for example, a known dye known to have a property that can be aligned according to an alignment state of a liquid crystal may be selected and used. As an anisotropic dye, a black dye can be used, for example. Such dyes are known as, for example, azo dyes or anthraquinone dyes, but are not limited thereto.

The dichroic ratio of the anisotropic dye may be, for example, 5 or more, 6 or more, or 7 or more. In the present specification, the term ``dichroic ratio'' means, for example, in the case of a p-type dye, a value obtained by dividing the absorption of polarized light parallel to the long axis direction of the dye by the absorption of polarized light parallel to the direction perpendicular to the long axis direction. I can. The anisotropic dye may satisfy the dichroic ratio in at least a portion of the wavelength or any one wavelength within the wavelength range of the visible light region, for example, in the wavelength range of about 380 nm to 700 nm or about 400 nm to 700 nm. The upper limit of the dichroic ratio may be, for example, 20 or less, 18 or less, 16 or less, or about 14 or less.

The ratio of the anisotropic dye in the polarizing layer may be appropriately adjusted according to the optical properties required for the polarizing plate. For example, the polarizing layer may include 0.1% to 5% by weight of the anisotropic dye.

As the alignment layer, a contact alignment layer, such as a rubbing alignment layer, or an alignment layer known to be capable of exhibiting alignment characteristics by a non-contact method such as irradiation of linearly polarized light including a photo-alignment layer compound may be used.

In one example, the alignment layer may be a photo-alignment layer. The photo-alignment layer may include a photo-alignment compound. In the present application, the term photo-alignment compound may refer to a compound that is orientationally ordered through irradiation of light and capable of aligning adjacent liquid crystal compounds or the like in a predetermined direction in the aligned state. The orientation compound may be a monomolecular compound, a monomeric compound, an oligomeric compound, or a polymeric compound.

The polarizing layer may be formed directly on the alignment layer. In the present specification, that A is directly formed on B may mean that A and B are in contact with each other without an intermediate medium therebetween.

The polarizing plate may further include a substrate under the alignment layer. The alignment layer may be formed directly on the substrate.

As the substrate, a known transparent substrate may be used. Examples of the substrate may be an inorganic film or a plastic film such as a glass film, a crystalline or amorphous silicon film, a quartz or indium tin oxide (ITO) film. As the substrate, an optically isotropic substrate or an optically anisotropic substrate such as a retardation layer may be used.

As a plastic substrate, TAC (triacetyl cellulose); COP (cycloolefin copolymer) such as norbornene derivatives; PMMA (poly(methyl methacrylate); PC (polycarbonate); PE (polyethylene); PP (polypropylene)) PVA (polyvinyl alcohol); DAC (diacetyl cellulose); Pac (polyacrylate); PES (poly ether sulfone); PEEK (polyetheretherketon) ); PPS (polyphenylsulfone), PEI (polyetherimide); PEN (polyethylenemaphthatlate); PET (polyethyleneterephtalate); PI (polyimide); PSF (polysulfone); PAR (polyarylate) or amorphous fluororesin, etc. It is not limited thereto.

The polarizing plate of the present application can be applied to various optical devices. For example, the polarizing plate may be applied to a display device. The display device includes a liquid crystal display device, an organic EL (electroluminescence) display device, an inorganic EL display device, a field emission display device (FED), a surface field emission display device (SPED), and an electronic paper. A display device using (electronic ink or electrophoretic element), a plasma display device, a projection display device (for example, a grating light valve (GLV) display device, a display having a digital micro-mirror device (Digital Light Processing)) Device] and a piezoelectric ceramic display device, but are not limited thereto. A method of configuring the display device is not particularly limited, and a conventional method may be applied as long as the polarizing plate of the present application is used.

The present application may provide a smectic liquid crystal compound having excellent horizontal alignment on a single alignment layer. When the Smectic liquid crystal compound is applied to a polarizing plate, a polarizing plate having an excellent dichroic ratio may be provided. The polarizing plate may be applied to various optical elements such as a display device.

Hereinafter, the polarizing element will be described in more detail through Examples and Comparative Examples, but the scope of the present application is not limited by the contents presented below.

Example One

A smectic liquid crystal compound of the following formula (A) was prepared according to the following Scheme A.

[Formula A]

[Scheme A]

[Production Example 1] Synthesis of Compound 2

Diethyl ether was added to a flask containing compound 1 (1.0 equiv.) and pTSA (0.05 equiv.), and then DHP (1.0 equiv.) was added, followed by stirring at room temperature overnight. After washing with NaOH (aq, 1.8 M 1.12 equiv.), wash the obtained water layer with diethyl ether and cool. After acidification with acetic acid (1.12 equiv.) and cooling at -18°C, the resulting solid is filtered, washed with water and dried to obtain 40 g of compound 2 in a 21% yield.

[Production Example 2] Synthesis of Compound 4

In a flask containing compound 3 (1.0 equiv.), 7-bromoheptanenitrile (1.7 equiv.), K2CO3 (1.7 equiv.), and KI (0.3 equiv.), 2-butanone was added to reflux overnight, followed by filtration and the solvent was removed. The obtained intermediate is _{dissolved in EtOH-H 2} O solvent, added with KOH (3.0 equiv.), refluxed overnight, and then cooled to room temperature. 1 N HCl solution is added to lower the pH to 1~2, the resulting solid is filtered and washed with water until the pH of the filtrate becomes 6~7, and 14 g of compound 4 can be obtained in 89% yield of the product.

[Production Example 3] Synthesis of Compound 5

Add anhydrous dichloromethane to a flask containing Compound 2 (1.0 equiv.), Compound 4 (1.2 equiv.), and DMAP (1.3 equiv.) to dissolve it, cool to 0°C, and add EDC (2.6equiv.) to 15. After stirring for a minute and then stirring overnight at room temperature, silica filter was performed twice under dichloromethane. When the solvent is removed and dried, 18 g of compound 5 can be obtained in an 80% yield.

[Production Example 4] Synthesis of Compound 6

After dissolving ethanol in a flask containing compound 5 (1.0 equiv.), heated to 50°C, PPTS (0.2 equiv.) was added under argon atmosphere. The reaction product was stirred at 50° C. overnight and then put in ice water to precipitate. The resulting precipitate was filtered and washed with water and hexane to obtain 11 g of compound 6 in an 80% yield.

[Preparation Example 5] Synthesis of Compound 7

DMF was added to a flask containing compound 3 (1.0 equiv.), 6-Bromo-1-hexanol (1.7 equiv.), K ₂ CO ₃ (1.7 equiv.), and KI (0.3 equiv.), and stirred at 140° C. overnight. After filtering, EA is added to the filtrate, washed with water, dried with anhydrous magnesium sulfate, filtered, and the solvent is removed. The obtained intermediate is _{dissolved in EtOHH 2} O solvent, added with KOH (3.0 equiv.), refluxed overnight, and cooled to room temperature. 1N HCl solution is added to lower the pH to 1~2 to filter the resulting solid, and wash with water until the pH of the filtrate becomes 6~7, the product can be obtained 14 g of compound 7 in 89% yield.

[Production Example 6] Synthesis of Compound 8

Compound 7 (1.0 equiv.), diethylaniline (1.2 equiv.), and BHT were dissolved in anhydrous THF and heated to 50°C. Add acryloyl chloride (1.2 equiv.) slowly and stir overnight. The solution from which the solid was formed is water and ice. Pour into a solution containing 0.1 wt% HCl, filter the solid, and wash twice with water and hexane. After drying, recrystallization was performed under EtOH to obtain 11.31 g of compound 8 in 48% yield.

[Production Example 7] Synthesis of Compound 9

Add anhydrous dichloromethane to a flask containing Compound 6 (1.0 equiv.), Compound 8 (1.2 equiv.), and DMAP (1.3 equiv.) to dissolve it, cool to 0°C, and add EDC (2.6equiv.) to 15. After stirring for a minute and then stirring overnight at room temperature, silica filter was performed twice under dichloromethane. When the solvent is removed and dried, 11 g of compound 9 can be obtained in a yield of 77%.

1H NMR (CDCl3, standard TMS) (ppm):

8.14 (4H, d), 7.26 (4H, s), 6.98 (4H, d), 6.40 (1H, dd), 6.10 (1H, dd), 5.82 (1H, dd), 4.19 (2H, t), 4.05 (4H, m), 1.78 (8H, m), 1.49 (6H, m), 1.35 (4H, m)

Comparative example One

As Comparative Example 1, a smectic liquid crystal compound of the following formula (B) was prepared.

[Formula B]

Example 2

A polarizing plate was manufactured by forming a polarizing layer including the smectic liquid crystal compound of Example 1 and a dichroic dye on the alignment layer.

Comparative example 2

A polarizing plate was manufactured in the same manner as in Example 1, except that the Smectic liquid crystal compound of Comparative Example 1 was used as the Smectic liquid crystal.

Optical property evaluation

As a result of evaluating horizontal alignment on a single alignment layer for the Smectic liquid crystal compounds of Example 1 and Comparative Example 1, Example 1 was superior to Comparative Example 1 in horizontal alignment.

As a result of evaluating the dichroic ratio of the polarizing plates of Example 2 and Comparative Example 2, the dichroic ratio of Example 2 was higher than that of Comparative Example 2.

Claims (11)

A polarizing layer comprising a smectic liquid crystal compound and an anisotropic dye, and
Including an alignment layer under the polarizing layer,
The smectic liquid crystal compound is represented by the following formula (1),
The anisotropic dye is a polarizing plate having a dichroic ratio of 5 or more:
[Formula 1]

In Formula 1, A and A'are independently of each other -CH ₂ -, -O-, or -S-,
B and B'are independently of each other -COO- or -OCO-,
C is a phenylene group, a cyclohexeylene group, or a naphthylene group,
D and D'are independently of each other a hydrocarbon group having 4 to 12 carbon atoms,
E is a polymerizable functional group,
F is -CN. The polarizing plate of claim 1, wherein A and A'are each -O-. The polarizing plate of claim 1, wherein B and B'are each -COO-. The polarizing plate of claim 1, wherein C is a phenylene group. The polarizing plate of claim 1, wherein D and D'are each an alkylene group having 6 carbon atoms. In claim 1, E is a polarizing plate of a (meth)acrylate group. delete delete The polarizing plate of claim 1, wherein the smectic liquid crystal compound is horizontally aligned in the polarizing layer. The polarizing plate of claim 1, wherein the alignment layer is a photo-alignment layer. The polarizing plate of claim 1, further comprising a transparent substrate under the alignment layer.