Liquid crystal capsule, and capsule solution, optical film, optical device, and variable transmittance device using same

Abstract

The present invention relates to a liquid crystal capsule comprising: a core containing a liquid crystal and an emulsifier; and a polymer shell formed on the surface of the core, wherein the emulsifier includes a polyglyceryl monoester compound or a polyglyceryl diester compound.

Description

Liquid crystal capsule, and capsule liquid using the same, optical film, optical device, transmittance variable device

[0001] Cross-citation with related application(s)

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2025-0016670 dated February 10, 2025, and all contents disclosed in the document of said Korean patent application are incorporated herein as part of this specification.

[0003] The present invention relates to a liquid crystal capsule capable of realizing a high haze variability at a lower voltage, and a capsule liquid, an optical film, an optical device, and a transmittance variability device using the same.

[0004] Polymer Dispersed Liquid Crystals (PDLC) films are composite materials that can be applied to high-brightness projection displays or high-contrast reflective display devices, in which liquid crystal molecules of several micrometers are dispersed within a polymer between conductive films. The operating principle of PDLC is that light incident on a polymer layer in which liquid crystals are dispersed is scattered due to the difference in refractive index between the liquid crystals and the polymer, resulting in an opaque state; however, by applying an electric field, the direction of the liquid crystals is aligned, and by changing the refractive index, the scattering and transmission of light are controlled, resulting in a transparent state.

[0005] As such, PDLC devices do not require a separate polarizer, so they do not require a polarizer structurally, and they do not require an alignment process, allowing them to be manufactured in a simple manner. This makes them applicable to smart glass and smart screens for buildings and automobiles that correspond to switchable windows, and they can also be applied as black PDLC films for transparent OLEDs. In addition, they can be manufactured in a flexible form depending on the material used as the substrate.

[0006] Specifically, liquid crystal-based smart windows refer to active windows that can control transmittance using glass containing a separate liquid crystal layer, and this technology is applicable not only to buildings but also to the mobility sector. Through existing polymer dispersed liquid crystal (PDLC) technology, liquid crystal domains of several micrometers in size could be manufactured by mixing liquid crystals with monomers capable of photo or thermal polymerization and utilizing the phase separation between the polymer and the liquid crystal that occurs during polymerization. PDLC films can implement light-blocking or transmission modes by causing the liquid crystals within the domains of several micrometers in size to match or mismatch the refractive index of the polymer matrix depending on the application of voltage on / off.

[0007] In particular, when manufacturing color-modifying PDLCs containing dyes, issues arise such as the anisotropic dyes within the polymer not aligning uniformly according to the electric field, and specifically, contamination of the polymer matrix by the dyes occur. Consequently, various studies are underway on encapsulated liquid crystal composites in which the liquid crystal and anisotropic dye are encapsulated within a polymer shell, resulting in excellent mechanical properties, high uniformity, and the prevention of dye-induced contamination of the polymer matrix.

[0008] However, as the liquid crystal and anisotropic dye are encapsulated in a polymer shell, there was a limitation in that the orientation of the liquid crystal was changed only when a higher voltage was applied due to the high interaction that occurs as the contact area between the liquid crystal enclosed in the capsule and the material contained in the capsule shell increases.

[0009] The present invention is intended to provide a liquid crystal capsule capable of realizing a high haze variability at a lower voltage.

[0010] In addition, the present invention is intended to provide a capsule liquid, an optical film, an optical device, and a transmittance variable device manufactured using the liquid crystal capsule.

[0011] To solve the above problem, the present specification provides a liquid crystal capsule comprising: a core containing a liquid crystal and an emulsifier; and a polymer shell formed on the surface of the core, wherein the emulsifier comprises a polyglyceryl monoester compound or a polyglyceryl diester compound.

[0012] In addition to the above, a capsule solution comprising the liquid crystal capsule and the solvent is provided.

[0013] In addition to the above, an optical film comprising the liquid crystal capsule is provided.

[0014] The present specification also provides an optical device comprising the optical film.

[0015] The present specification also provides a transmittance variable device comprising the optical film.

[0016] A liquid crystal capsule according to a specific embodiment of the invention, and a capsule liquid, an optical film, an optical device, and a transmittance variable device using the same, will be described in more detail below.

[0017]

[0018] Unless explicitly stated otherwise in this specification, technical terms are used merely to refer to specific embodiments and are not intended to limit the invention.

[0019] The singular forms used in this specification include plural forms unless the phrases clearly indicate otherwise.

[0020] As used in this specification, the meaning of 'includes' specifies certain characteristics, regions, integers, steps, actions, elements, and / or components, and does not exclude the existence or addition of other specific characteristics, regions, integers, steps, actions, elements, components, and / or groups.

[0021] Also, in this specification, terms including ordinal numbers such as 'first' and 'second' are used for the purpose of distinguishing one component from another and are not limited by said ordinal numbers. For example, within the scope of the present invention, the first component may also be named the second component, and similarly, the second component may be named the first component.

[0022] In this specification, derivative compounds refer to compounds that have been modified from an organic compound as a base, such as by introducing functional groups, oxidation, reduction, or substitution of atoms, to the extent that the structure and properties of the base are not significantly altered.

[0023] In this specification, the term "substitution" means that another functional group is bonded in place of a hydrogen atom in a compound, and the substitution site is not limited to the site where the hydrogen atom is substituted, that is, the site where the substituent can be substituted, and in the case of two or more substitutions, the two or more substituents may be the same or different from each other.

[0024] In this specification, the term “substituted or unsubstituted” means substituted or unsubstituted with one or more substituents selected from the group consisting of deuterium; halogen group; cyano group; nitro group; hydroxyl group; carbonyl group; ester group; imide group; amide group; primary amino group; carboxyl group; sulfonic acid group; sulfonamide group; phosphine oxide group; alkoxy group; aryloxy group; alkyl thioxy group; aryl thioxy group; alkyl sulfoxy group; aryl sulfoxy group; silyl group; alkyl group; cycloalkyl group; alkenyl group; aryl group; aralkyl group; ar alkenyl group; alkyl aryl group; alkoxysilylalkyl group; aryl phosphine group; or heterocyclic groups comprising one or more of N, O, and S atoms, or substituted or unsubstituted with two or more of the exemplified substituents connected. For example, “a substituent with two or more connected substituents” may be a biphenyl group.

[0025] In this specification, the weight-average molecular weight refers to the weight-average molecular weight equivalent to polystyrene measured by the GPC method. In the process of measuring the weight-average molecular weight equivalent to polystyrene measured by the GPC method, commonly known analytical devices, detectors such as a refractive index detector, and analytical columns may be used, and commonly applied temperature conditions, solvents, and flow rates may be applied. As a specific example of the above measurement conditions, a Waters PL-GPC220 instrument is used with a Polymer Laboratories PLgel MIX-B 300 mm long column, the evaluation temperature is 160 ℃, 1,2,4-trichlorobenzene is used as the solvent, the flow rate is 1 mL / min, the sample is prepared at a concentration of 10 mg / 10 mL and supplied in an amount of 200 μL, and the value of Mw can be obtained using a calibration curve formed using a polystyrene standard.

[0026] The present invention will be described in more detail below.

[0027]

[0028] 1. Liquid crystal capsule

[0029] According to one embodiment of the invention, a liquid crystal capsule may be provided comprising: a core containing a liquid crystal and an emulsifier; and a polymer shell formed on the surface of the core, wherein the emulsifier comprises a polyglyceryl monoester compound or a polyglyceryl diester compound.

[0030] The inventors confirmed through experiments that by using a polyglyceryl monoester or polyglyceryl diester compound as an emulsifier contained together with the liquid crystal in the inner core of the capsule, as in the liquid crystal capsule of the above-mentioned embodiment, the anchoring energy with the surface contacted by the liquid crystal is reduced, thereby enabling a high haze variability rate even at a lower voltage, and thus completed the invention.

[0031] Specifically, the liquid crystal capsule of the above embodiment may include a core containing liquid crystal. The liquid crystal capsule structure according to the present invention is characterized by containing liquid crystal inside a shell made of a polymer. This can improve the uniformity of the liquid crystal particles.

[0032] The liquid crystal is not particularly limited, but examples include nematic liquid crystal, smectic liquid crystal, cholesteric liquid crystal, chiral nematic liquid crystal, etc. The specific type of liquid crystal compound is not limited, and various liquid crystals known in the prior art can be used without limitation. The liquid crystal compound is not particularly limited, but may be composed of fluorine-based or cyanide-based compounds, or a mixture thereof.

[0033] The above liquid crystal may have a dielectric anisotropy (△ε) of 10 or more, or 13.5 or more, or 14 or more, or 15 or more, or 20 or less, or 10 to 20, or 13.5 to 20, or 14 to 20, or 15 to 20. Since liquid crystal molecules align in the direction of the electric field within the above range, it can be applied to an optical film that increases transmittance by applying voltage. In addition, because significant refraction of light occurs, an optical film that is more opaque than when no voltage is applied can be manufactured. The above dielectric anisotropy (△ε) refers to the difference between the extraordinary dielectric anisotropy (εe, dielectric constant in the long axis direction) and the ordinary dielectric anisotropy (εo, dielectric constant in the short axis direction). The method for measuring the dielectric anisotropy of the liquid crystal contained in the above liquid crystal capsule is not limited, and various conventionally known methods can be applied without limitation.

[0034] In addition, the liquid crystal may have a refractive index anisotropy (△n) of 0.2 or more, or 0.21 or more, or 0.22 or more, or 0.5 or less, or 0.2 to 0.5, or 0.21 to 0.5, or 0.22 to 0.5. Within the above range, a liquid crystal cell capable of switching between a haze mode and a non-haze mode with excellent haze characteristics can be implemented. The refractive index anisotropy (△n) refers to the difference between the ordinary refractive index and the extraordinary refractive index. The method for measuring the refractive index anisotropy of the liquid crystal contained in the liquid crystal capsule is not limited, and various conventionally known methods can be applied without limitation.

[0035] Meanwhile, the core may further include an emulsifier. The emulsifier is a surfactant used for the formation of liquid crystal droplets and can induce a high haze variability even at lower voltages.

[0036] The above emulsifier may include a polyglyceryl monoester compound or a polyglyceryl diester compound. The polyglyceryl monoester compound may refer to a compound having one ester group within the molecule among ester compounds derived from the polyglyceryl. Additionally, the polyglyceryl diester compound may refer to a compound having two ester groups within the molecule among ester compounds derived from the polyglyceryl.

[0037] The above polyglyceryl monoester compound or polyglyceryl dieester compound may have a weight-average molecular weight of 3000 g / mol or less, or 2000 g / mol or less, or 1500 g / mol or less, or 1300 g / mol or less, or 100 g / mol or more, or 900 g / mol or more, or 100 g / mol to 3000 g / mol, or 100 g / mol to 2000 g / mol, or 100 g / mol to 1500 g / mol, or 100 g / mol to 1300 g / mol, or 900 g / mol to 3000 g / mol, or 900 g / mol to 2000 g / mol, or 900 g / mol to 1500 g / mol, or 900 g / mol to 1300 g / mol. If the weight-average molecular weight of the above polyglyceryl monoester compound or polyglyceryl diester compound increases excessively, it may hinder the movement of liquid crystal molecules, leading to high voltage and low haze variability.

[0038] The above polyglyceryl monoester compound or polyglyceryl diester compound may be a reaction product of polyglyceryl and carboxylic acid.

[0039] Additionally, the carboxylic acid may be an unsubstituted carboxylic acid. That is, the carboxylic acid does not have other functional groups (e.g., hydroxyl groups) bonded in place of hydrogen atoms in the compound.

[0040] Specifically, the carboxylic acid may have a hydroxyl group content of less than 0.001 mol% based on 100 mol% of the carboxylic acid. That is, the carboxylic acid may not contain hydroxyl groups or may contain them in extremely small amounts. If the hydroxyl group content of the carboxylic acid increases to 0.001 mol% or more based on 100 mol% of the carboxylic acid, it may hinder the movement of liquid crystal molecules, thereby causing high voltage and low haze variability.

[0041] The above carboxylic acid may be a saturated carboxylic acid or an unsaturated carboxylic acid. The above unsaturated carboxylic acid is a carboxylic acid containing intramolecular carbon double bonds, and the above saturated carboxylic acid is a carboxylic acid that does not contain intramolecular carbon double bonds.

[0042] The above carboxylic acid may have 10 to 30 carbon atoms, or 10 to 20 carbon atoms, or 13 to 19 carbon atoms, or 13 to 15 carbon atoms, or 17 to 19 carbon atoms.

[0043] Specific examples of the above-mentioned carboxylic acids include oleic acid, myristic acid, or stearic acid.

[0044] More specifically, the polyglyceryl monoester compound may be one or more compounds selected from the group consisting of polyglyceryl monooleate, polyglyceryl monomyristate, and polyglyceryl monostearate. That is, the polyglyceryl monoester compound may be polyglyceryl monooleate, polyglyceryl monomyristate, polyglyceryl monostearate, or a mixture of two or more of these.

[0045] As a more specific example, the polyglyceryl monoester compound may be polyglyceryl-10 monooleate, polyglyceryl-10 monomyristate, polyglyceryl-10 monostearate, or a mixture of two or more of these.

[0046] In addition, the polyglyceryl diester compound may be one or more compounds selected from the group consisting of polyglyceryl dioleate, polyglyceryl dimyristate, and polyglyceryl distearate. That is, the polyglyceryl diester compound may be polyglyceryl dioleate, polyglyceryl dimyristate, polyglyceryl distearate, or a mixture of two or more of these.

[0047] As a more specific example, the polyglyceryl diester compound may be polyglyceryl-10 dioleate, polyglyceryl-10 dimyristate, polyglyceryl-10 distearate, or a mixture of two or more of these.

[0048] Meanwhile, with respect to 100 parts by weight of the liquid crystal, the emulsifier content may be 0.1 to 50 parts by weight, or 0.1 to 20 parts by weight, or 0.5 to 20 parts by weight, or 1 to 20 parts by weight, or 5 to 11 parts by weight. If the emulsifier content is excessively reduced with respect to 100 parts by weight of the liquid crystal, the vertical alignment of the liquid crystal by the emulsifier is induced, which has a limitation in that it is difficult to sufficiently induce a high transmittance variability even at lower voltages. In addition, if the emulsifier content is excessively increased with respect to 100 parts by weight of the liquid crystal, an excess amount of emulsifier may form colloidal micelles, causing a problem in which the surface tension of the solution drops sharply.

[0049] Meanwhile, the core may further include an anisotropic dye. The anisotropic dye is not particularly limited as long as it is a dopable anisotropic dye, and specifically may be S-428, M-483, M412 (Mitsui FineChemical), etc.

[0050] Meanwhile, the core may further include a siloxane-based additive. The siloxane-based additive is an additive capable of lowering the interfacial tension of the liquid crystal. Accordingly, a liquid crystal capsule containing the siloxane-based additive and the liquid crystal together in the core can sufficiently lower the surface anchoring energy of the liquid crystal within the capsule.

[0051] The above siloxane-based additive may have a molar mass of 500 g / mol or less, or 100 g / mol to 500 g / mol. The above siloxane-based additive may include a trisiloxane-based compound. The above trisiloxane-based compound may include a trisiloxane compound or a derivative thereof. As a specific example, the above siloxane-based additive may be octamethyltrisiloxane or hexamethylcyclotrisiloxane.

[0052] In particular, with respect to 100 parts by weight of the liquid crystal, the content of the siloxane-based additive may be 0.1 to 50 parts by weight, or 0.1 to 20 parts by weight, or 0.5 to 20 parts by weight, or 0.5 to 10 parts by weight, or 0.9 to 1 part by weight. If the content of the siloxane-based additive is excessively reduced with respect to 100 parts by weight of the liquid crystal, the effect of lowering the surface tension of the liquid crystal by the siloxane-based additive is not sufficiently realized, and there is a limitation in that the surface anchoring energy of the liquid crystal within the capsule cannot be sufficiently lowered. In addition, if the content of the siloxane-based additive is excessively increased with respect to 100 parts by weight of the liquid crystal, a problem may occur in which the liquid crystal state (mesophase state) changes into an isotropic liquid phase.

[0053] Meanwhile, the liquid crystal capsule of the above embodiment may include a polymer shell formed on the surface of the core. The shell may be a single-layer shell made of a single polymer material, or a double-layer shell or a multi-layer shell made of different polymer materials to achieve improved mechanical properties and particle uniformity. Accordingly, the uniformity of the liquid crystal particles can be improved, and the problem of contamination by dye can be improved at the same time.

[0054] The material forming the shell has the same refractive index as the matrix polymer in which the liquid crystal composite is dispersed, and while specific examples are not particularly limited, it may be selected from polyvinyl alcohol, polyurea, polyacrylic, polyurethane, polyamide including nylon, polyacetal, and polyester.

[0055] However, to give a specific example, the polymer shell formed on the surface of the core may be made of polyvinyl alcohol (PVA) resin crosslinked with glyoxal. There are no particular restrictions on the type of PVA, and various types of PVA with different molecular weights or saponification rates may be appropriately selected depending on the purpose. Glyoxal is used as the crosslinking agent for crosslinking the PVA.

[0056] Meanwhile, the average diameter of the liquid crystal capsule may be 1 μm or more, or 1 μm to 500 μm. If the average diameter of the liquid crystal capsule is reduced excessively, there is a problem that the driving voltage increases and power consumption increases. In addition, if the average diameter of the liquid crystal capsule is increased excessively, visible light is scattered and the haze increases.

[0057] The liquid crystal capsule may be a group of individual particles having an average diameter of 1 μm or more, or 1 μm to 500 μm, and the individual particles included in this group may have an average diameter of 1 μm or more, or 1 μm to 500 μm. More specifically, 95% or 99% of the individual particles included in the group may have a diameter of 1 μm or more, or 1 μm to 500 μm.

[0058] The present application also provides uses for the liquid crystal capsule. The liquid crystal capsule of the present application can be used in various optical modulation devices applicable to liquid crystals. Accordingly, the present application provides an optical modulation device having a substrate; and a liquid crystal layer formed on one surface of the substrate and comprising the liquid crystal capsule. The manufacturing method and type of the optical modulation device are well known in the art and can be manufactured using known manufacturing methods without limitation. The optical modulation device includes, but is not limited to, a smart window, an isotropic film, a polarization control film, or a flexible LCD, etc.

[0059] The method for manufacturing the above liquid crystal capsule is not significantly limited, and various conventionally known methods for manufacturing liquid crystal capsules may be applied without limitation. However, for example, the method comprises: (1) a process of preparing a mixed solution formed by mixing a mixed material containing liquid crystal, an emulsifier, and polyvinyl alcohol (PVA) in a solvent; (2) a process of forming a droplet from the mixed solution; (3) a process of placing polyvinyl alcohol (PVA) around the droplet; and (4) a process of manufacturing a liquid crystal capsule containing liquid crystal within a polymer shell by crosslinking the polyvinyl alcohol (PVA) using a crosslinking agent to form a polymer shell surrounding the liquid crystal.

[0060] In the process of preparing a mixed solution by mixing the above (1) liquid crystal, emulsifier, and polyvinyl alcohol (PVA) with a solvent, the solvent is not particularly limited and can be appropriately selected according to the purpose, and examples include pure water such as ion-exchanged water, ultrafiltered water, reverse osmosis water, distilled water, or ultrapure water. If necessary, additional additives may be added.

[0061] In the process of preparing a mixed solution by mixing the above (1) liquid crystal, emulsifier, and polyvinyl alcohol (PVA) with a solvent, examples of methods for mixing the liquid crystal, emulsifier, polyvinyl alcohol (PVA), and additive with the solvent are not significantly limited, and various methods used in conventionally known emulsification reactions can be applied without limitation. However, as an example, a method of mixing the liquid crystal with a solution containing the solvent, emulsifier, and polyvinyl alcohol can be used, but is not limited thereto.

[0062] In the process of forming droplets from the above (2) mixed solution, the droplets are dispersed in a dispersion medium, and more specifically, the droplets are dispersed in a dispersion medium in a state where an emulsifier covers the liquid crystal.

[0063] One method for preparing the above droplets is to produce droplets using a dispersion-type emulsification device.

[0064] As for the dispersion-type emulsification device, there are no particular restrictions as long as droplets of the desired particle size are obtained, and it can be appropriately selected according to the purpose; for example, a homomixer, which is a device for mixing liquids, or a homogenizer, which is a device for finely and uniformly grinding particles, can be used. Furthermore, there are no particular restrictions on the dispersion method; for example, any dispersion method such as stirring, ultrasound, or high pressure can be used.

[0065] In the present invention, as a dispersion emulsification device, various dispersion emulsification devices such as a high-speed homogenizer, an ultrasonic homogenizer, a high-pressure homogenizer, and a homo mixer may be used.

[0066] In addition, a more preferred embodiment of the droplet preparation process may include a droplet preparation process comprising a first preparation process for preparing droplets using a first dispersion emulsification device and a second preparation process for preparing droplets smaller than the particle size obtained in the first preparation process using a second dispersion emulsification device.

[0067] As for the first and second dispersion emulsification devices, there are no particular restrictions as long as droplets of the desired particle size are obtained, and various dispersion emulsification devices such as the high-speed homogenizer, ultrasonic homogenizer, high-pressure homogenizer, and homo mixer described above can be appropriately combined and used.

[0068] In the process of placing polyvinyl alcohol (PVA) around the above (3) droplets, coacervation can proceed in which the PVA gathers around the liquid crystal composition under a droplet dispersion at a predetermined temperature. For example, it is preferable to set the solution temperature of the droplet dispersion in the coacervation process to room temperature or higher.

[0069] In the process of manufacturing a liquid crystal capsule containing a liquid crystal within a polymer shell by crosslinking polyvinyl alcohol (PVA) using the above (4) crosslinking agent to form a polymer shell surrounding the liquid crystal, the crosslinking reaction is preferably carried out under acidic conditions. As for the acidic conditions, it is preferable that the pH be in the range of 1 to 5, and more preferable that the pH be about 3.

[0070]

[0071] 2. Capsule solution

[0072] Meanwhile, according to another embodiment of the invention, a capsule solution comprising a liquid crystal capsule and a solvent of the first embodiment may be provided. The details regarding the liquid crystal capsule include the details described above with respect to the first embodiment.

[0073] The above solvent is not particularly limited and can be appropriately selected according to the purpose, and examples include pure water such as ion-exchanged water, ultrafiltered water, reverse osmosis water, distilled water, or ultrapure water.

[0074] The above capsule solution contains liquid crystal capsules dispersed in a solvent. That is, the above capsule solution may be a liquid crystal capsule dispersion. The above capsule solution may also be used as a coating solution for forming a liquid crystal layer. For example, a liquid crystal layer is formed by applying the capsule solution onto a support substrate to form a film.

[0075]

[0076] 3. Optical film

[0077] Meanwhile, according to another embodiment of the invention, an optical film comprising a liquid crystal capsule of the first embodiment may be provided. The details regarding the liquid crystal capsule include the details described above with respect to the first embodiment.

[0078] The optical film may include a matrix and liquid crystal capsules of the above embodiment dispersed within the matrix. Although the content of the matrix is ​​not particularly limited, for example, the matrix may be a transparent material. Although specific examples of the matrix are not particularly limited, for example, it may be selected from polyvinyl alcohol, polyurea, polyacrylic, polyurethane, polyamide including nylon, polyacetal, and polyester.

[0079] For a more specific example, the optical film may be formed by applying the capsule liquid of the other embodiment onto a supporting substrate to form a film.

[0080] Specific details regarding the above optical film can be applied without limitation to various conventionally known optical films. For example, regarding the structure, composition, manufacturing method, physical properties, and applications of the optical film, various details widely known in the conventional film field can be applied without limitation.

[0081] However, for example, the above optical film can be used in a transmittance variable film.

[0082]

[0083] 4. Optical device

[0084] Meanwhile, according to another embodiment of the invention, an optical device comprising an optical film of the other embodiment may be provided. The details regarding the optical film include the details described above regarding the other embodiment.

[0085] The content regarding the above optical device can be applied without limitation to various conventionally known optical devices. For example, regarding the specific structure, size, manufacturing method, physical properties, and applications of the optical device, various contents widely known in the conventional display field can be applied without limitation.

[0086] However, for example, the optical device may be a light modulation device including an optical film of the other embodiment. Specific examples of the light modulation device are not particularly limited, but may include, for example, a smart window, an isotropic film, a polarization control film, or a liquid crystal display, an organic electroluminescent display, etc.

[0087] More specifically, examples of the above optical device include a liquid crystal display element having a set of opposing substrates, an electrode formed on one or both opposing surfaces of each of the set of substrates, a liquid crystal layer formed by applying a liquid crystal capsule liquid of the present invention disposed between the substrates, and a means for applying an electric field to the liquid crystal capsule of the present invention in the liquid crystal layer through the electrode.

[0088] The above optical device may have a threshold voltage of 50 V or less, or 40 V or less, or 30 V or less, or 20 V or less, or 1 V or more, or 1 V to 50 V, or 1 V to 40 V, or 1 V to 30 V, or 1 V to 20 V, or 20 V to 40 V. The above threshold voltage refers to the voltage at 90% haze of the maximum haze, and as the optical device has a threshold voltage within the range described above, the optical device may be able to operate at a lower voltage. The method for measuring the above threshold voltage is not limited, and various methods widely known in the field of conventional liquid crystal-containing optical devices may be applied without limitation. However, for example, voltage may be applied through a function generator and measured using a haze meter (Nippon Denshoku, NDH7000).

[0089] In addition, the optical device has haze at an applied voltage of 0V. off class Haze at an applied voltage of 100V onThe difference value △Haze may be 40% or more, or 45% or more, or 49% or more, or 50% or more, or 55% or more, or 58% or more, or 60% or less, or 40% to 60%, or 45% to 60%, or 49% to 60%, or 50% to 60%, or 55% to 60%, or 58% to 60%. As the optical device has a △Haze value within the range described above, the optical device can achieve an excellent haze variability even at lower voltages. The method of measuring the haze is not limited, and various methods widely known in the field of conventional liquid crystal-containing optical devices can be applied without limitation. However, for example, it can be measured using a haze meter (Nippon Denshoku, NDH7000) while applying voltage through a function generator.

[0090]

[0091] 5. Variable transmittance device

[0092] Meanwhile, according to another embodiment of the invention, a transmittance variable device comprising an optical film of the other embodiment may be provided. The details regarding the optical film include the details described above regarding the other embodiment.

[0093] The above description regarding the variable transmittance device may apply various conventionally known variable transmittance devices without limitation. For example, regarding the specific structure, size, manufacturing method, physical properties, and applications of the variable transmittance device, various contents widely known in the field of conventional liquid crystal capsules may be applied without limitation. However, as an example, the variable transmittance device may include a polarization layer and a variable transmittance layer, and the polarization layer or the variable transmittance layer may contain the dichroic dye of the above embodiment as a light modulating material.

[0094] The transmittance variable device of the present application can be applied to any device to which transmittance variation can be applied. For example, the transmittance variable device of the present application can be applied to a sunroof, automotive glass, goggles, sunglasses, or helmet, etc., to provide a transmittance variable device. As long as the transmittance variable device includes the transmittance variable device of the present application, other parts or structures, etc., are not particularly limited, and all contents known in the art may be appropriately applied.

[0095] According to the present invention, a liquid crystal capsule capable of realizing a high haze variability at a lower voltage, and a capsule liquid, an optical film, an optical device, and a transmittance variability device using the same may be provided.

[0096] The invention is described in more detail in the following examples. However, the following examples are merely illustrative of the invention, and the scope of the invention is not limited by the following examples.

[0097]

[0098] <Example: Preparation of Liquid Crystal Capsule and Capsule Solution>

[0099] Example 1

[0100] 0.25 g of polyglyceryl-10 monooleate (Cas number: 79665-93-3; weight-average molecular weight: 1203.399 g / mol) was added as an emulsifier to an aqueous solution mixed with 0.65 g of polyvinyl alcohol (PVA) and 46.5 g of water, and dissolved by stirring. Subsequently, 2.3 g of liquid crystal (dielectric anisotropy (△ε) 15.8, refractive anisotropy (△n) 0.2235) was added, and the mixture was emulsified using an IKA homogenizer T25 at 4,000 rpm for 30 minutes to form droplets.

[0101] Afterwards, the solution was heated to 40°C under stirring and PVA was adsorbed onto the droplet surface for 18 hours.

[0102] Subsequently, 1.6 g of a 40% aqueous glyoxal solution was added as a crosslinking agent, and the pH of the solution was adjusted to 3, and the adsorbed PVA was crosslinked at 40 ℃ for 18 hours.

[0103] After concentrating the solution with a rotary evaporator for 1 hour, a capsule solution containing a liquid crystal capsule was obtained.

[0104]

[0105] Example 2

[0106] 0.25 g of polyglyceryl-10 monomyristate (Cas number: 87390-32-7; weight-average molecular weight: 969.16 g / mol) was added as an emulsifier to an aqueous solution mixed with 0.65 g of polyvinyl alcohol (PVA) and 46.5 g of water, and dissolved by stirring. Subsequently, 2.3 g of liquid crystal (dielectric anisotropy (△ε) 15.8, refractive anisotropy (△n) 0.2235) was added, and the mixture was emulsified using an IKA homogenizer T25 at 6,000 rpm for 30 minutes to form droplets.

[0107] Afterwards, the solution was heated to 40°C under stirring and PVA was adsorbed onto the droplet surface for 18 hours.

[0108] Subsequently, 0.8 g of a 40% aqueous glyoxal solution was added as a crosslinking agent, and the pH of the solution was adjusted to 3, and the adsorbed PVA was crosslinked at 40 ℃ for 18 hours.

[0109] After concentrating the solution with a rotary evaporator for 1 hour, a capsule solution containing a liquid crystal capsule was obtained.

[0110]

[0111] Example 3

[0112] A liquid crystal capsule and a capsule solution were prepared in the same manner as in Example 1, except that polyglyceryl-10 monostearate (Polyglyceryl-10 monostearate; Cas number: 79777-30-3; weight-average molecular weight: 1025.3 g / mol) was added instead of polyglyceryl-10 monooleate as the emulsifier.

[0113]

[0114] Example 4

[0115] A liquid crystal capsule and a capsule solution were prepared in the same manner as in Example 1, except that polyglyceryl-10 distearate (Polyglyceryl-10 distearate; Cas number: 12764-60-2; weight-average molecular weight: 1275.7 g / mol) was added instead of polyglyceryl-10 monostearate as the emulsifier.

[0116]

[0117] <Comparative Example: Preparation of Liquid Crystal Capsule and Capsule Solution>

[0118] Comparative Example 1

[0119] 0.5 g of polyglyceryl-3 polyricinoleate (Cas number: 68936-89-0; weight-average molecular weight: 3054 g / mol) was added as an emulsifier to an aqueous solution mixed with 1.3 g of polyvinyl alcohol (PVA) and 93.6 g of water, and dissolved by stirring. Subsequently, 4.6 g of liquid crystal (dielectric anisotropy (△ε) 15.8, refractive anisotropy (△n) 0.2235) was added, and the mixture was emulsified using an IKA homogenizer T25 at 6,000 rpm for 30 minutes to form droplets.

[0120] Afterwards, the solution was heated to 40°C under stirring and PVA was adsorbed onto the droplet surface for 18 hours.

[0121] Subsequently, 1.6 g of a 40% aqueous glyoxal solution was added as a crosslinking agent, and the pH of the solution was adjusted to 3, and the adsorbed PVA was crosslinked at 40 ℃ for 18 hours.

[0122] After concentrating the solution with a rotary evaporator for 2 hours, a capsule solution containing a liquid crystal capsule was obtained.

[0123]

[0124] <Experimental Example>

[0125] For the liquid crystal capsules or capsule liquids obtained in the above examples and comparative examples, physical properties were measured by the following method, and the results are shown in Table 1.

[0126]

[0127] 1. Physical properties of liquid crystal capsule films

[0128] (1) Thickness (㎛)

[0129] A liquid crystal capsule film was prepared by coating the capsule solution onto the ITO of a PET-ITO film using a film applicator and drying it at 70°C for 2 hours. The thickness of the liquid crystal capsule film was measured using an Alpha step (KLA TENCOR).

[0130] (2) △Haze (%), critical voltage (V)

[0131] After laminating the ITO surface of a PET-ITO film (GMP EXCELAM-SMART 655) onto the upper surface of the liquid crystal capsule film, an electrode tape was attached to the ITO surface.

[0132] Haze of a liquid crystal capsule film with no applied voltage (haze at an applied voltage of 0V) off (%) and Haze, which is the haze of the liquid crystal capsule film to which voltage is applied through the function generator (haze at an applied voltage of 100V). onAfter measuring (%) using a haze meter (Nippon Denshoku, NDH7000), based on this, △Haze = Haze off (%) - Haze on (%) was calculated. And the critical voltage was determined through the voltage at 90% haze of the maximum haze.

[0133]

[0134] Measurement Results of Experimental Examples and Comparative Examples Classification Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Emulsifier Polyglyceryl-10 Monooleate Polyglyceryl-10 Monomyristate Polyglyceryl-10 Monostearate Polyglyceryl-10 Distearate Polyglyceryl-3 Polyricinoleate Thickness (㎛) 25.5 28.8 29.3 24.6 26.1 ΔHaze (%) 58.8 54 5.7 54 9.9 55 7.7 53 8.70 Critical Voltage (V) 20 20 40 40 60

[0135] As shown in Table 1 above, the liquid crystal capsule of the example had a threshold voltage of 20V to 40V, which is lower than that of the comparative example, and a ΔHaze value of 45.75% to 58.85%, which is higher than that of the comparative example. Accordingly, it was confirmed that it is possible to drive at a low voltage while achieving an excellent haze variability.

Claims

1. A core containing a liquid crystal and an emulsifier; and A polymer shell formed on the surface of the core; comprising The above emulsifier is a liquid crystal capsule comprising a polyglyceryl monoester compound or a polyglyceryl diester compound.

2. In Paragraph 1, The above polyglyceryl monoester compound or polyglyceryl diester compound is a liquid crystal capsule having a weight-average molecular weight of 3000 g / mol or less.

3. In Paragraph 1, The above polyglyceryl monoester compound or polyglyceryl diester compound is a liquid crystal capsule that is a reaction product of polyglyceryl and a carboxylic acid.

4. In Paragraph 3, The above carboxylic acid is an unsubstituted carboxylic acid, a liquid crystal capsule.

5. In Paragraph 3, The above carboxylic acid is a liquid crystal capsule having a hydroxyl group content of less than 0.001 mol% based on 100 mol% of carboxylic acid.

6. In Paragraph 3, A liquid crystal capsule in which the above carboxylic acid is a saturated carboxylic acid or an unsaturated carboxylic acid.

7. In Paragraph 3, The above carboxylic acid is a liquid crystal capsule having 10 to 30 carbon atoms.

8. In Paragraph 1, A liquid crystal capsule, wherein the above polyglyceryl monoester compound is one or more compounds selected from the group consisting of polyglyceryl monooleate, polyglyceryl monomyristate, and polyglyceryl monostearate.

9. In Paragraph 1, A liquid crystal capsule, wherein the above polyglyceryl diester compound is one or more compounds selected from the group consisting of polyglyceryl dioleate, polyglyceryl dimyristate, and polyglyceryl distearate.

10. In Paragraph 1, The above liquid crystal is a liquid crystal capsule having a dielectric anisotropy (△ε) of 10 or more.

11. In Paragraph 1, The above liquid crystal is a liquid crystal capsule having a refractive index anisotropy (△n) of 0.2 or higher.

12. In Paragraph 1, The above core is a liquid crystal capsule further comprising a siloxane-based additive.

13. A capsule solution comprising the liquid crystal capsule and solvent of claim 1.

14. An optical film comprising the liquid crystal capsule of claim 1.

15. An optical device comprising the optical film of claim 14.

16. A transmittance variable device comprising the optical film of claim 14.