Liquid crystal device and emulsion composition

Abstract

A liquid crystal element comprising two substrates equipped with transparent electroconductive films, disposed so that the transparent electroconductive films face each other, and a liquid crystal-polymer composite film sandwiched between the two substrates equipped with transparent electroconductive films, wherein the liquid crystal-polymer composite film has a polymer matrix and a liquid crystal composition surrounded by the polymer matrix, the liquid crystal composition contains a liquid crystal component and a dichroic pigment, the dielectric anisotropy of the liquid crystal component is positive, the NI point is 110-150°C, the refractive index anisotropy of the liquid crystal component is 0.01-0.1, and the liquid crystal-polymer composite film can be switched between a transparent state and a colored state by application of a voltage thereto.

Description

[Technical Field]

[0001] The present invention relates to a liquid crystal device and an emulsion composition, and more particularly to a liquid crystal device that can be switched between a transparent state and a colored state, and an emulsion composition that can be used in the liquid crystal device. [Background technology]

[0002] In recent years, there has been growing demand for smart glass, which can electrically switch the transparency of glass. Liquid crystal, electrochromic, and SPD (Suspend Particle Device) methods have been proposed as light-control materials for smart glass. Among these, the liquid crystal method has attracted attention because of its overwhelmingly short response time, which reduces user stress.

[0003] Among the liquid crystal display devices, PDLC (Polymer Dispersed Liquid Crystals) is widely known (Non-Patent Document 1). PDLC has a structure in which a liquid crystal-polymer composite film, in which particulate liquid crystal is dispersed in a polymer matrix, is sandwiched between two transparent conductive substrates.

[0004] Among PDLCs, normal mode driving is the most common. When no voltage is applied to a normal mode PDLC, the liquid crystal molecules align along the walls of the polymer matrix, resulting in a mismatch in refractive index between the liquid crystal region and the polymer matrix. This mismatch causes light scattering, resulting in a cloudy appearance and a screen effect. On the other hand, when voltage is applied to a PDLC, the liquid crystal molecules align in the direction of the electric field, causing the refractive index of the liquid crystal region and the polymer matrix to match, allowing light to pass through and becoming transparent.

[0005] PDLC has been put to practical use as light-control shutters for the purpose of improving design and protecting privacy in windows, doors, and partitions in trains, automobiles, and other vehicles, as well as in buildings such as business buildings and hospitals. It is also used in display devices that show characters and figures.

[0006] PDLC can be made into a film element because of its flexibility due to the aforementioned liquid crystal-polymer composite film structure. In addition, the film element can be cut and shaped. Taking advantage of these characteristics, users can easily apply it to glass.

[0007] In recent years, with the growing trend toward energy conservation, attempts have been made to use smart glass in windows to reduce heating and cooling loads by controlling the amount of sunlight entering a room. However, in the case of PDLC, although it is possible to switch between light scattering and non-scattering, most of the scattering is forward scattering, so light passes through the element. As a result, the amount of transmitted light cannot be controlled at all, and it does not contribute to energy savings.

[0008] Patent documents 1 to 3 disclose guest-host liquid crystal (GH liquid crystal) smart glass, in which a dichroic dye is added to the liquid crystal. The guest-host liquid crystal system switches between a transparent state and a colored state by electrically switching the absorbance of the liquid crystal element, so the amount of transmitted light can be controlled. However, in order to make a guest-host liquid crystal into a cuttable film element, a matrix is required to surround the liquid crystal and support the film structure, as in PDLC.

[0009] Patent Documents 4 to 6 disclose guest-host PDLCs that combine PDLCs with guest-host liquid crystals, and are expected to be used as film elements that can control the amount of transmitted light.

[0010] In Patent Document 4, a liquid crystal-polymer composite film is produced by polymerization-induced phase separation through photopolymerization. In the method of Patent Document 4, the dichroic dye in the liquid crystal absorbs light, inhibiting photopolymerization, resulting in poor curing of the polymer matrix, which reduces the reliability of the liquid crystal device. This problem is particularly significant when attempting to improve the light-blocking properties of the liquid crystal device.

[0011] In Patent Document 5, a liquid crystal-polymer composite film is produced using an aqueous emulsion composition. This production method using an emulsion composition has the advantage that it is easier to obtain the desired film structure than the production method using polymerization-induced phase separation in Patent Document 4, and that there is no decrease in reliability due to insufficient curing of the polymer matrix. Therefore, a liquid crystal device with improved light-blocking properties can be obtained. According to Patent Document 5, if the birefringence (Δn) of the liquid crystal is 0.15 or less and the order parameter S of the dichroic dye is 0.75 or more, the change range of the visible light transmittance of the PDLC is 30% or more and the haze in the transparent state is 10% or less. However, the visible light transmittance here indicates the linear transmittance of linear light that does not include scattered light, and when forward scattered light is included, the range of change in the amount of transmitted light is still very small, which poses the problem that the amount of solar radiation cannot be controlled at all.

[0012] In Patent Document 6, a liquid crystal element with a wide change range (dynamic range) of visible light transmittance and low haze is obtained by controlling the refractive index anisotropy and order parameter of a guest-host liquid crystal. However, the liquid crystal element of Patent Document 6 has a problem in that the dynamic range of visible light transmittance changes when driven at high temperatures for a long period of time, and its reliability is not necessarily sufficient. In automobile applications, the temperature inside the vehicle can become high, and such a change in the dynamic range becomes an obstacle to the application of liquid crystal elements to automobile applications.

[0013] [Patent Document 1] Special Publication No. 2016-510907 [Patent Document 2] Special Publication No. 2016-536634 [Patent Document 3] Special Publication No. 2017-511895 [Patent Document 4] Japanese Patent Application Laid-Open No. 2011-190314 [Patent Document 5] Japanese Patent Application Publication No. 60-252687 [Patent Document 6] Japanese Patent Application Laid-Open No. 2000-347223

[0014] [Non-Patent Document 1] DAHiggins,Advanced Materials 2000,12,No.4 Summary of the Invention

[0015] An object of the present invention is to provide a liquid crystal element that can electrically control the amount of transmitted light and can be cut and shaped, has a wide dynamic range of visible light transmittance, and exhibits little degradation in the dynamic range even after operation at high temperatures.

[0016] The present inventors have discovered that by using a liquid crystal component having a predetermined dielectric anisotropy and refractive index anisotropy in a liquid crystal composition containing a liquid crystal component and a dichroic dye, and by increasing its NI point (nematic-isotropic phase transition temperature), the visible light transmittance of a liquid crystal element can be made to have a large change range (dynamic range), and the dynamic range can be maintained even after operation at high temperatures, thereby completing the present invention.

[0017] [1] A liquid crystal element comprising two substrates with transparent conductive films arranged so that the transparent conductive films face each other, and a liquid crystal-polymer composite film sandwiched between the two substrates with transparent conductive films, the liquid crystal-polymer composite film has a polymer matrix and a liquid crystal composition surrounded by the polymer matrix, the liquid crystal composition contains a liquid crystal component and a dichroic dye; The liquid crystal component has a positive dielectric anisotropy and an NI point of 110°C or higher and 150°C or lower, the refractive index anisotropy of the liquid crystal component is 0.01 or more and 0.1 or less, The liquid crystal-polymer composite film can be switched between a transparent state and a colored state by applying a voltage to the liquid crystal element.

[0018] [2] The liquid crystal device according to [1], wherein the liquid crystal composition has an average particle size of 2 μm or more and 50 μm or less.

[0019] [3] The liquid crystal device according to [1], wherein the liquid crystal composition has an average particle size of 0.01 μm or more and less than 2 μm.

[0020] [4] The liquid crystal device according to any one of [1] to [3], wherein the dichroic dye contains an anthraquinone dye and / or an azo dye.

[0021] [5] The liquid crystal device according to any one of [1] to [4], wherein the content of the dichroic dye relative to 100% by mass of the liquid crystal composition is 0.1% by mass or more and 20% by mass or less.

[0022] [6] The liquid crystal device according to any one of [1] to [5], wherein the liquid crystal component is a nematic liquid crystal or a chiral nematic liquid crystal.

[0023] [7] The liquid crystal element according to any one of [1] to [6], wherein the polymer constituting the polymer matrix contains at least one selected from the group consisting of polyurethane, polyacrylic, polyvinyl alcohol, and modified products thereof.

[0024] [8] The liquid crystal device according to any one of [1] to [7], wherein the total light transmittance in the colored state is 0.1% or more and 30% or less.

[0025] [9] The liquid crystal device according to any one of [1] to [8], wherein the total light transmittance in the transparent state is more than 30% and not more than 80%.

[0026]

[10] An emulsion composition in which a liquid crystal composition is dispersed in a medium containing water, the medium is a medium in which a polymer is dispersed or dissolved, the liquid crystal composition contains a liquid crystal component and a dichroic dye; The liquid crystal component has a positive dielectric anisotropy and an NI point of 110°C or higher and 150°C or lower, The emulsion composition, wherein the refractive index anisotropy of the liquid crystal component is 0.01 or more and 0.1 or less.

[0027]

[11] The emulsion composition according to

[10] , wherein the average particle size of the liquid crystal composition in the emulsion composition is 2 μm or more and 50 μm or less.

[0028]

[12] The emulsion composition according to

[10] , wherein the average particle size of the liquid crystal composition in the emulsion composition is 0.01 μm or more and less than 2 μm.

[0029]

[13] The emulsion composition according to any one of

[10] to

[12] , wherein the dichroic dye contains an anthraquinone dye and / or an azo dye.

[0030]

[14] The emulsion composition according to any one of

[10] to

[13] , wherein the content of the dichroic dye relative to 100% by mass of the liquid crystal composition is 0.1% by mass or more and 20% by mass or less.

[0031]

[15] The emulsion composition according to any one of

[10] to

[14] , wherein the liquid crystal component is a nematic liquid crystal or a chiral nematic liquid crystal.

[0032]

[16] The emulsion composition according to any one of

[10] to

[15] , wherein the polymer contains at least one selected from the group consisting of polyurethane, polyacrylic, polyvinyl alcohol, and modified products thereof. [Effects of the Invention]

[0033] According to the present invention, a liquid crystal element capable of electrically controlling the amount of transmitted light and capable of being cut and shaped is provided, which has both high light-blocking properties and a wide dynamic range, and furthermore, the dynamic range is prevented from decreasing even when driven at high temperatures.

[0034] The liquid crystal element of the present invention, having the above-mentioned properties, is useful for windows, screens, displays, etc. For example, it can be used as a view blocking element in windows, partitions, etc. of buildings and vehicles. It can also be used as a display for billboards, show windows, computer terminals, projections, etc. The liquid crystal device of the present invention has high driving reliability, particularly at high temperatures, and is therefore particularly useful in environments where temperatures rise due to direct sunlight or the like, for example, in automobile applications. [Brief explanation of the drawings]

[0035] [Figure 1] FIG. 1 is a chart showing the haze (dynamic range ΔHaze) after 65 hours, 133 hours, and 228 hours from the start of continuous driving in Examples 3 and 4 and Comparative Example 2. [Figure 2] FIG. 2 is a chart showing the total light transmittance (dynamic range ΔTT) after 65 hours, 133 hours, and 228 hours from the start of continuous driving in Examples 3 and 4 and Comparative Example 2. [Figure 3] FIG. 3 is a chart showing the haze (dynamic range ΔHaze) after 65 hours, 133 hours, and 228 hours from the start of continuous driving in Examples 7 and 8 and Comparative Example 4. [Figure 4] FIG. 4 is a chart showing the total light transmittance (dynamic range ΔTT) after 65 hours, 133 hours, and 228 hours from the start of continuous driving in Examples 7 and 8 and Comparative Example 4. DETAILED DESCRIPTION OF THE INVENTION

[0036] The present invention will be described in detail below. The following description is an example of an embodiment of the present invention, and the present invention is not limited to the following description as long as it does not deviate from the gist of the present invention. The present invention can be implemented by modifying it as desired within the scope of the gist of the present invention.

[0037] [Liquid Crystal Element] The liquid crystal element of the present invention comprises two substrates with transparent conductive films arranged so that their transparent conductive films face each other, and a liquid crystal-polymer composite film sandwiched between the two substrates with transparent conductive films, wherein the liquid crystal-polymer composite film has a polymer matrix and a liquid crystal composition surrounded by the polymer matrix, the liquid crystal composition containing a liquid crystal component and a dichroic dye, the liquid crystal component having a positive dielectric anisotropy, an NI point of 110°C or more and 150°C or less, and a refractive index anisotropy of 0.01 or more and 0.1 or less, and the liquid crystal-polymer composite film can be switched between a transparent state and a colored state by applying a voltage.

[0038] [mechanism] In the liquid crystal device of the present invention, the liquid crystal-polymer composite film has a polymer matrix and a liquid crystal composition surrounded by the polymer matrix, resulting in a flexible, cuttable, and shapable liquid crystal device. The liquid crystal composition contains a liquid crystal component and a dichroic dye, allowing it to exhibit sufficient light absorption in a colored state. Furthermore, by having the NI point of the liquid crystal component be between 110°C and 150°C, the dynamic range is wide and can be maintained for a long time even when driven at high temperatures. One way to widen the dynamic range is to increase the degree of order (order parameter) of the liquid crystal, and a higher NI point tends to result in a higher degree of order. However, if the NI point is too high, the lower limit temperature for nematic phase operation rises, falling outside the practical temperature range. Specifically, if the NI point exceeds 150°C, the lower limit for nematic phase operation often exceeds 0°C. For this reason, the NI point of the liquid crystal component used in the present invention is set to 150°C or lower.

[0039] Since the dielectric anisotropy (Δε) of the liquid crystal component used in the present invention is positive, the resulting liquid crystal-polymer composite film is transparent when a voltage is applied and is colored when no voltage is applied, but may have a memory property in which voltage application is required only when switching between the transparent state and the colored state.

[0040] In the present invention, the voltage refers to a DC voltage, an AC voltage, a pulse voltage, or a combination thereof, which has an effective value equal to or greater than a threshold value. In the present invention, the transparent state refers to the state of the liquid crystal-polymer composite film when the voltage is applied or when no voltage is applied, and the transparent state is the state in which the total light transmittance of the liquid crystal-polymer composite film is greater when a voltage is applied or when no voltage is applied. In addition, in the present invention, the colored state refers to the state of the liquid crystal-polymer composite film when the above voltage is applied or when no voltage is applied, and the colored state is the state in which the total light transmittance of the liquid crystal-polymer composite film is smaller when a voltage is applied or when no voltage is applied.

[0041] [Liquid crystal-polymer composite film] The liquid crystal-polymer composite film included in the liquid crystal element of the present invention (hereinafter, sometimes referred to as the "liquid crystal-polymer composite film of the present invention") has a polymer matrix (hereinafter, sometimes referred to as the "polymer matrix of the present invention") and a liquid crystal composition (hereinafter, sometimes referred to as the "liquid crystal composition of the present invention") surrounded by the polymer matrix. Such a liquid crystal-polymer composite film is generally known as a PDLC.

[0042] The liquid crystal-polymer composite film has a polymer matrix and a liquid crystal composition surrounded by the polymer matrix, which gives the liquid crystal element flexibility. This structure also minimizes leakage of the liquid crystal composition when the liquid crystal element is cut, and the polymer matrix protects the liquid crystal composition from degradation factors such as oxygen and moisture, making it possible to cut and reshape the element.

[0043] <Liquid Crystal Composition> The liquid crystal composition of the present invention may be dispersed in a polymer matrix, and may be regularly aligned. The shape of the liquid crystal composition of the present invention may be any of a sphere, a spheroid, a cylinder, a triangular prism, a square prism, a hexagonal prism, etc., or a polygonal prism, such as a distorted shape. Among these, a sphere, a spheroid, a cylinder, a regular polygonal prism, such as a regular triangular prism, a regular square prism, or a regular hexagonal prism, is preferred because it tends to weaken the light scattering of the liquid crystal-polymer composite film, increase the light absorption of the dichroic dye when colored, and reduce the haze in the transparent state.

[0044] From the viewpoint of the transparency of the resulting device, the size of the liquid crystal composition, when observed from the film surface of the liquid crystal-polymer composite film, is preferably 2 μm or more, more preferably 5 μm or more. Furthermore, it is preferably 50 μm or less, more preferably 30 μm or less. When the average particle size is above the above lower limit, the light scattering of the liquid crystal-polymer composite film tends to be weaker, and the haze in the transparent state tends to be smaller. At the same time, the light scattering of the liquid crystal-polymer composite film in the colored state is also weakened, which relatively improves the contribution of the dichroic dye to light absorption, enabling more transparent control of the total light transmittance. When the average particle size is below the above upper limit, the granularity of the liquid crystal composition is eliminated, and the uniformity of the appearance of the liquid crystal device tends to be improved.

[0045] From the viewpoint of the light-shielding properties of the resulting device, the average particle size of the liquid crystal composition, when observed from the film surface of the liquid crystal-polymer composite film, is preferably 0.01 μm or more, more preferably 0.1 μm or more. Furthermore, it is preferably less than 2 μm, more preferably 1 μm or less. When the average particle size is less than the above upper limit, the light scattering of the liquid crystal-polymer composite film tends to be strong, the haze in the light-shielding state tends to be large, and the dynamic range (the difference in haze between the colored state and the transparent state) tends to be wide. At the same time, the opportunity for light absorption by the dichroic dye due to multiple scattering increases, which tends to lower the total light transmittance and widen the dynamic range (the difference in total light transmittance between the colored state and the transparent state). However, if the average particle size is smaller than the above lower limit (significantly smaller than the visible light wavelength), the effect is weakened. Therefore, the average particle size of the liquid crystal composition is preferably equal to or greater than the above lower limit.

[0046] The average particle diameter of the liquid crystal composition is the median diameter based on the number of particles. When the liquid crystal composition is observed from the film surface of the liquid crystal-polymer composite film, if the shape is not circular but polygonal such as an ellipse, triangle, rectangle, or hexagon, or if the shape is distorted, the particle size can be determined by referring to the diameter of the smallest encompassing circle.

[0047] The liquid crystal composition of the present invention contains a liquid crystal component (hereinafter, sometimes referred to as the "liquid crystal component of the present invention") and a dichroic dye (hereinafter, sometimes referred to as the "dichroic dye of the present invention"). Such a liquid crystal composition is generally known as a guest-host liquid crystal.

[0048] Although not particularly limited, the content of the dichroic dye relative to 100% by mass of the liquid crystal composition is preferably 0.1% by mass or more, more preferably 1% by mass or more, and even more preferably 3% by mass or more, and is preferably 20% by mass or less, more preferably 15% by mass or less, and even more preferably 10% by mass or less, relative to 100% by mass of the liquid crystal composition. When the content of the dichroic dye is equal to or greater than the lower limit, the liquid crystal element tends to exhibit greater light absorption in the colored state and the amount of transmitted light tends to be smaller. When the content of the dichroic dye is equal to or less than the upper limit, separation or precipitation of the dichroic dye is less likely to occur, and the reliability of the liquid crystal element tends to be improved.

[0049] The liquid crystal composition may contain additives within the range that does not impair the performance of the liquid crystal element of the present invention, such as a polymer precursor, a polymerization initiator, a light stabilizer, an antioxidant, a thickener, a polymerization inhibitor, a photosensitizer, an adhesive, an antifoaming agent, a surfactant, and a chiral agent.

[0050] The chiral agent may be any chiral compound compatible with the liquid crystal component, and may be a synthetic or commercially available product. The chiral agent may itself exhibit liquid crystallinity or may have a polymerizable functional group. The chiral agent may be either dextrorotatory or levorotatory, and a dextrorotatory chiral agent and a levorotatory chiral agent may be used in combination. Furthermore, a chiral agent having a large positive dielectric anisotropy and low viscosity is preferred from the viewpoint of reducing the driving voltage and response speed of a liquid crystal element, and a chiral agent having a large helical twisting power, which is an index of the force with which the chiral agent twists the liquid crystal, is preferred.

[0051] Examples of commercially available chiral agents include CB15 (trade name, manufactured by Merck & Co.), C15 (trade name, manufactured by Merck & Co.), S-811 (trade name, manufactured by Merck & Co.), R-811 (trade name, manufactured by Merck & Co.), S-1011 (trade name, manufactured by Merck & Co.), and R-1011 (trade name, manufactured by Merck & Co.).

[0052] When the liquid crystal composition of the present invention contains a chiral agent, there are no particular restrictions on the content thereof, but the reciprocal (1 / p) of the chiral pitch p [μm], determined by the ratio of the amount of the liquid crystal component and the amount of the chiral agent used, is preferably 0.01 to 0.5 [ / μm], and particularly preferably 0.01 to 0.3 [ / μm]. If the reciprocal (1 / p) of the chiral pitch is equal to or greater than the lower limit, the light absorption efficiency of the dichroic dye is increased, and the light-blocking properties in the colored state can be improved. If it is equal to or less than the upper limit, it is possible to suppress voltage rise.

[0053] <Liquid crystal components> The dielectric anisotropy (Δε) of the liquid crystal component of the present invention is positive, and in this case, the liquid crystal is in a colored state when no voltage is applied, and in a transparent normal mode when a voltage is applied.

[0054] The NI point (nematic phase-isotropic phase transition temperature) of the liquid crystal component of the present invention is 110°C or higher and 150°C or lower, preferably 120°C or higher and 140°C or lower. If the NI point is above the lower limit, the dynamic range of transmittance change tends to be maintained even when continuously driven at a high temperature of about 90°C. Furthermore, the higher the NI point, the wider the dynamic range of transmittance change tends to be. On the other hand, since an increase in the NI point tends to increase the lower limit of the temperature of the nematic phase, from the viewpoint of operation at low temperatures, the NI point is preferably below the upper limit.

[0055] The method for measuring the NI point of the liquid crystal component is not particularly limited, but it can be obtained by first dissolving the liquid crystal composition and then observing the phase transition or phase separation due to temperature increase using a polarizing microscope.

[0056] The refractive index anisotropy (Δn) of the liquid crystal component of the present invention is 0.01 or more, preferably 0.02 or more, and more preferably 0.03 or more. It is also preferably 0.1 or less, and 0.10 or less. When Δn is equal to or less than the upper limit, light scattering at the interface between the polymer matrix and the liquid crystal composition tends to be reduced, and haze in the transparent state tends to be reduced. On the other hand, when Δn is equal to or greater than the lower limit, the order parameter of the liquid crystal composition tends to be large.

[0057] The refractive index anisotropy of a liquid crystal component can be obtained by directly determining the ordinary refractive index (no) and extraordinary refractive index (ne) of the liquid crystal component and then calculating the difference between them (Δn = ne - no). If this is difficult to do directly, it can also be calculated by determining the phase difference (retardation: R) when light passes through a sample of thickness d and dividing this by the thickness d (R = Δnd).

[0058] The liquid crystal contained in the liquid crystal component may be nematic liquid crystal, cholesteric liquid crystal, smectic liquid crystal, etc. In view of low cost, nematic liquid crystal or cholesteric liquid crystal is preferred. Furthermore, cholesteric liquid crystal (chiral nematic liquid crystal) may be obtained by adding a chiral agent to nematic liquid crystal.

[0059] When using a known liquid crystal substance as the liquid crystal component, specific examples include various low molecular weight compounds or mixtures such as biphenyls, phenylcyclohexanes, and cyclohexylcyclohexanes, as described in "Liquid Crystal Device Handbook," edited by the 142nd Committee of the Japan Society for the Promotion of Science, Japan Industrial Newspaper Co., Ltd. (1989), pp. 152-192, and "Liquid Crystal Handbook," edited by the Liquid Crystal Handbook Editorial Committee, Maruzen Co., Ltd. (2000), pp. 260-330. Polymeric compounds or mixtures such as those described in "Liquid Crystal Handbook," edited by the Liquid Crystal Handbook Editorial Committee, Maruzen Co., Ltd. (2000), pp. 365-415, can also be used. Examples of compounds constituting nematic liquid crystals include the following compounds.

[0060] [ka]

[0061] Nematic liquid crystals and cholesteric liquid crystals (chiral nematic liquid crystals) having low viscosity and high dielectric anisotropy are preferred in terms of high-speed response of liquid crystal elements and ease of emulsion production.

[0062] <Dichroic dye> The dichroic dye contained in the liquid crystal composition of the present invention may be any dichroic dye compound that is compatible with the liquid crystal component, and may be a dichroic dye having a positive or negative Δε. In addition, the dichroic dye itself may exhibit liquid crystallinity.

[0063] Specific examples of the dichroic dye of the present invention include azo dyes, anthraquinone dyes, naphthoquinone dyes, perylene dyes, quinophthalone dyes, tetrazine dyes, and benzothiadiazole dyes. When using a known dichroic dye, it is possible to use azo dyes, anthraquinone dyes, or mixtures thereof, such as those described in "Liquid Crystal Device Handbook," edited by the 142nd Committee of the Japan Society for the Promotion of Science, published by the Japan Industrial Newspaper Co., Ltd. (1989), pages 192-196 and 724-730. Among these, anthraquinone dyes or azo dyes are preferred because they tend to have a large absorption coefficient, high solubility in the liquid crystal component, and high light resistance. The dichroic dye may be one kind or a mixture of two or more kinds. Although there is no particular limitation, it is preferable that the dichroic dye contains an anthraquinone-based and / or azo-based dye in an amount of 20 mass % or more, and more preferably 50 mass % or more.

[0064] Specific examples of the dichroic dye of the present invention include compounds represented by the following formulas.

[0065] [ka]

[0066] In the above formula, each X independently represents -NH- or -S-, n represents 0 or 1, and Ar represents a phenylene group or a naphthylene group. R represents a hydrogen atom, an alkyl group, an alkoxy group, a cyclohexyl group which may have a substituent, a phenyl group, a phenylcyclohexyl group, or a cyclohexylcyclohexyl group.

[0067] <Polymer matrix> The polymer matrix of the present invention is preferably a hydrophilic polymer. In this case, there are no particular limitations as long as it is hydrophilic, but it is preferable to select a polymer whose refractive index matches the ordinary refractive index (no) of the liquid crystal component. Since the no of the liquid crystal component is typically around 1.5, the refractive index of the polymer matrix is preferably 1.45 or more and 1.55 or less.

[0068] Examples of polymers that constitute the polymer matrix include natural polymers such as gelatin and gum arabic; synthetic polymers such as polyvinyl alcohol, polyurethane, polyurea, polyacrylic, polyamine, polyamide, polyethylene, polypropylene, polystyrene, and polyacrylonitrile, and modified products thereof; and copolymers such as methacrylate / acrylonitrile, urethane / acrylate, and acrylate / acrylonitrile. A crosslinking structure may also be introduced into the polymer using a crosslinking agent.

[0069] The polymer preferably has high dispersibility or solubility in water, and is preferably gelatin, polyvinyl alcohol, polyurethane, polyurea, polyacrylic, polyamine, or a modified product thereof, more preferably at least one selected from the group consisting of polyurethane, polyacrylic, polyvinyl alcohol, or a modified product thereof, even more preferably at least one selected from the group consisting of polyurethane, polyacrylic, or a modified product thereof, and particularly preferably polyacrylic. These polymers may be used alone or in combination of two or more.

[0070] Polyurethanes are classified according to the skeleton of the polyisocyanate or polyol. Examples of polyisocyanate skeletons include aliphatic polyurethanes consisting of an aliphatic carbon skeleton and aromatic polyurethanes containing an aromatic ring in the polyisocyanate. Among these, aliphatic polyurethanes are preferred because of their high light resistance. Examples of polyol skeletons include polyethers, polyesters, and polycarbonates, with polyethers being preferred because of their excellent film adhesion.

[0071] Polyacrylics are polymers of various acrylate monomers, such as compounds represented by the following formula:

[0072] [ka]

[0073] In the above formula, X 1 represents a hydrogen atom or a methyl group, and R 1 represents a hydrogen atom, a halogen atom, a hydroxy group, a linear or branched alkyl group having from 1 to 20 carbon atoms which may have a substituent, a linear or branched alkoxy group having from 1 to 20 carbon atoms which may have a substituent, or a cyclic hydrocarbon group having from 1 to 10 carbon atoms which may have a substituent.

[0074] Polyacrylic may be copolymerized with monomers other than acrylate, and examples of copolymers include acrylate-styrene, acrylate-vinyl acetate, acrylate-acrylonitrile, acrylate-urethane, acrylate-ester, acrylate-silicone, etc. The main chain may be composed of a copolymer of acrylate and other monomers, or other polymers may be grafted onto the polyacrylic main chain.

[0075] The polymer matrix may contain small molecules, such as light stabilizers, antioxidants, thickeners, polymerization inhibitors, photosensitizers, adhesives, antifoaming agents, surfactants, and water-soluble dyes, as long as the small molecules do not impair the performance of the liquid crystal device of the present invention.

[0076] <Ratio of liquid crystal composition to polymer matrix> In the liquid crystal-polymer composite film of the present invention, the ratio of the total mass of the liquid crystal composition to the total mass of the polymer matrix is preferably 0.5 or more, more preferably 1 or more, where the total mass of the polymer matrix is 1. Also, it is preferably 4 or less, more preferably 3 or less. When the ratio of the total mass of the liquid crystal composition to the total mass of the polymer matrix is equal to or greater than the above lower limit, the haze in the transparent state tends to be low and the driving voltage tends to be low. When the ratio of the total mass of the liquid crystal composition to the total mass of the polymer matrix is equal to or less than the above upper limit, the impact resistance and adhesion of the liquid crystal-polymer composite film tend to be improved.

[0077] [Substrate with transparent conductive film] Representative structures of the substrate with a transparent conductive film according to the present invention will be described below, but the present invention is not limited to these.

[0078] Examples of materials for the substrate include inorganic transparent substances such as glass and quartz, and colorless and transparent substances such as metals, metal oxides, semiconductors, ceramics, plastic plates, plastic films, etc. These substrates may be used as a single plate or as a laminate of multiple plates. The substrate may be provided with a hard coat layer for the purpose of protecting it from scratches and dirt, or a sharp cut layer or band pass layer for blocking light rays in a specific wavelength range.

[0079] The transparent conductive film constituting the electrode is formed on the substrate by, for example, forming a thin film of a metal oxide, metal, semiconductor, organic conductive material, etc., over the entire surface or part of the substrate by known coating methods, printing methods, vapor deposition methods such as sputtering, etc. Alternatively, the conductive thin film may be partially etched after formation. In particular, to obtain a large-area liquid crystal element, it is desirable to use an electrode substrate in which an ITO (a mixture of indium oxide and tin oxide) electrode is formed on a transparent polymer film such as PET by vapor deposition methods such as sputtering, printing, etc., from the standpoints of productivity and processability.

[0080] The substrate may have wiring for connecting between electrodes or for connecting the electrodes to the outside, such as a segment driving electrode substrate, a matrix driving electrode substrate, or an active matrix driving electrode substrate.

[0081] Furthermore, the electrode surface provided on the substrate may be covered entirely or partially with a protective film or alignment film made of organic compounds such as polyimide, polyamide, silicone, and cyanide compounds, inorganic compounds such as SiO2, TiO2, and ZrO2, or mixtures thereof.

[0082] The substrates may be subjected to an alignment treatment to align the liquid crystal relative to the substrate surface. When the substrates are aligned, for example, both substrates may be homogeneously aligned or homeotropically aligned, or one may be homogeneously aligned and the other homeotropically aligned, a so-called hybrid. For these alignment treatments, the electrode surfaces may be directly rubbed, a conventional alignment film such as polyimide used in TN liquid crystals and STN liquid crystals may be used, or a photo-alignment treatment may be performed.

[0083] The opposing substrate may have an adhesive layer containing a resin body on the periphery thereof to adhere and support the substrate.

[0084] The edges or cut surfaces of the liquid crystal element of the present invention can be sealed with tapes such as adhesive tape, thermocompression tape, and thermosetting tape, or curable resins such as thermosetting resins, photocurable resins, moisture-curable resins, room-temperature curable adhesives, anaerobic adhesives, epoxy adhesives, silicone adhesives, fluororesin adhesives, polyester adhesives, and vinyl chloride adhesives, or thermoplastic resins to prevent the liquid crystal composition from seeping out. This sealing may also have the effect of preventing deterioration of the liquid crystal element. In this case, the edges can be protected by covering the entire edges, or by pouring a curable resin or a thermoplastic resin into the liquid crystal element from the edges and solidifying it, followed by covering the resin with tape.

[0085] Between the opposing substrates with transparent conductive films, there may be present a spacer such as a spherical or cylindrical glass, plastic, ceramic, or plastic film. The spacer may be contained as a component of the emulsion composition of the present invention so that it is present in the liquid crystal-polymer composite film between the substrates, or it may be dispersed on the substrates during assembly of the liquid crystal element, or mixed with an adhesive so that it is present in the adhesive layer.

[0086] [Method of manufacturing liquid crystal-polymer composite film] The liquid crystal-polymer composite film of the present invention can be produced by applying the emulsion composition of the present invention described below to a substrate with a transparent conductive film and drying it. Known coating methods such as bar coating, blade coating, knife coating, die coating, screen coating, microgravure roll coating, reverse roll coating, kiss roll coating, dip roll coating, spin coating, and spray coating can be used as the coating method. Depending on the properties of the substrate, the substrate may be washed as appropriate.

[0087] The wet film thickness at the time of application is preferably 10 μm or more, more preferably 20 μm or more. Also, it is preferably 120 μm or less, more preferably 100 μm or less. When the wet film thickness is equal to or greater than the lower limit, the liquid crystal composition tends to be uniformly applied without variations in density. When the wet film thickness is equal to or less than the upper limit, the driving voltage tends to be reduced to a practical value, and the haze in the transparent state tends to be low.

[0088] The drying temperature when the emulsion composition is applied and dried is preferably 40° C. or higher, more preferably 50° C. or higher, and is preferably 100° C. or lower, more preferably 80° C. or lower. When the drying temperature is equal to or higher than the lower limit, the drying time is shortened to a practical time, and the amount of water remaining in the film is reduced, which tends to improve the reliability of the liquid crystal device. When the drying temperature is equal to or lower than the upper limit, the emulsion composition is less likely to undergo structural destruction such as coalescence or reverse phase formation during drying.

[0089] [Total light transmittance] The total light transmittance in this specification is measured by the method specified in JIS K7136. In this specification, light refers to visible light (wavelengths of 380 nm to 780 nm), and the total light transmittance is measured in the visible light region.

[0090] The total light transmittance in the colored state of the liquid crystal element of the present invention is preferably 30% or less, more preferably 25% or less, and even more preferably 20% or less. When the total light transmittance in the colored state is equal to or less than the above upper limit, the amount of transmitted light in the colored state can be reduced, and light blocking properties tend to be improved. On the other hand, the total light transmittance in the colored state is preferably 0.1% or more, more preferably 0.3% or more, and even more preferably 0.5% or more. When the total light transmittance in the colored state is equal to or more than the above lower limit, a wide dynamic range tends to be maintained.

[0091] The total light transmittance of the liquid crystal element of the present invention in the transparent state is preferably greater than 30%, more preferably 50% or more, and even more preferably 55% or more. The total light transmittance in the transparent state is preferably 80% or less, more preferably 70% or less. When the total light transmittance in the transparent state is within these ranges, the transparency of the element tends to be ensured.

[0092] The dynamic range of the total light transmittance (difference in total light transmittance between the colored state and the transparent state, ΔTT) of the liquid crystal element of the present invention is preferably 30 or more, and more preferably 35 or more. When the dynamic range is within this range, the obtained element tends to be easily recognized.

[0093] [Haze] The haze in this specification is measured by the method of JIS K7136.

[0094] From the viewpoint of transparency, the haze of the colored state of the liquid crystal element of the present invention is preferably 90% or less, more preferably 80% or less, and even more preferably 70% or less. When the haze of the colored state is equal to or less than the above upper limit, the light absorption of the dichroic dye in the colored state can be relatively increased, and a more transparent colored state can be obtained. On the other hand, the haze of the colored state is preferably 10% or more, more preferably 20% or more, and even more preferably 30% or more. When the haze of the colored state is equal to or more than the above lower limit, the glare of external light tends to be further reduced. Furthermore, from the viewpoint of light-blocking properties, the haze of the liquid crystal element of the present invention in the colored state is preferably 80% or more, more preferably 90% or more, and even more preferably 95% or more. When the haze of the colored state is equal to or greater than the above-mentioned lower limit, the opportunity for light absorption by the dichroic dye due to multiple scattering increases, and the total light transmittance tends to be lower. On the other hand, the haze of the colored state is preferably 99% or less. When the haze of the colored state is equal to or less than the above-mentioned upper limit, the haze in the transparent state tends to be reduced.

[0095] The haze of the liquid crystal element of the present invention in a transparent state is preferably 16% or less, more preferably 10% or less, and even more preferably 6% or less. The haze in a transparent state is preferably 0% or more, more preferably 1% or more. When the haze in a transparent state is within these ranges, a film with a transparent appearance and good visibility tends to be obtained.

[0096] The dynamic range of haze (difference in haze between the colored state and the transparent state, ΔHaze) of the liquid crystal element of the present invention is preferably 45 or more, and more preferably 50 or more. When it is in this range, the contrast between light-shielding and transparency becomes clear, and the difference between the visibility of the scenery seen through the film and the non-visibility of the scenery tends to become clear.

[0097] [Emulsion composition] The emulsion composition of the present invention is an emulsion composition in which a liquid crystal composition is dispersed in a medium containing water, the medium being a medium in which a polymer is dispersed or dissolved, the liquid crystal composition containing a liquid crystal component and a dichroic dye, the liquid crystal component having a positive dielectric anisotropy, an NI point of 110°C or more and 150°C or less, and a refractive index anisotropy of 0.01 or more and 0.1 or less.

[0098] The liquid crystal composition contained in the emulsion composition of the present invention is not particularly limited, and examples thereof include the liquid crystal composition used in the liquid crystal device of the present invention described above. The water-containing medium contained in the emulsion composition is also not particularly limited, and examples thereof include pure water or a mixture of water and an organic solvent.

[0099] Examples of the organic solvent include alcohols, ketones, ethers, esters, carboxylic acids, amines, etc. The organic solvent may be water-soluble or oil-soluble to the extent that it is slightly soluble in water, but it is preferable to mix it in an amount that allows it to be uniformly dissolved in water.

[0100] Examples of the polymer dispersed or dissolved in the medium include natural polymers such as gelatin and gum arabic; synthetic polymers such as polyvinyl alcohol, polyurethane, polyurea, polyacrylic, polyamine, polyamide, polyethylene, polypropylene, polystyrene, and polyacrylonitrile, and modified products thereof; and copolymers such as methacrylate / acrylonitrile, urethane / acrylate, and acrylate / acrylonitrile.

[0101] The polymer preferably has high dispersibility or solubility in water, and is preferably gelatin, polyvinyl alcohol, polyurethane, polyurea, polyacrylic, polyamine, or a modified product thereof, more preferably at least one selected from the group consisting of polyurethane, polyacrylic, polyvinyl alcohol, or a modified product thereof, even more preferably at least one selected from the group consisting of polyurethane, polyacrylic, or a modified product thereof, and particularly preferably polyacrylic. The polymer may be used alone or in combination of two or more.

[0102] In the present invention, "dispersion of a polymer" refers to a state in which polymer particles are suspended in a medium, and "dissolution of a polymer" refers to a state in which the polymer is dissociated into sufficiently small particles by solvation to form a homogeneous system. For details on dispersion and dissolution of polymers, see "Color Materials," Color Materials Association of Japan (2004), Vol. 77, No. 4, pp. 169-176.

[0103] In the emulsion composition of the present invention, the liquid crystal composition is dispersed in a medium containing water. The liquid crystal composition may be dispersed in a liquid state as it is, or may be dispersed in the form of microencapsulated liquid crystal in which the periphery of the liquid crystal composition is encapsulated with a polymer, a silica compound, inorganic nanoparticles, or the like. Examples of polymers that can be used to form capsules in microcapsule liquid crystals include natural polymers such as gelatin and gum arabic; synthetic polymers such as polyvinyl alcohol, polyurethane, polyurea, polyacrylic, polyamine, polyamide, polyethylene, polypropylene, polystyrene, and polyacrylonitrile, and modified products thereof; and copolymers such as methacrylate / acrylonitrile, urethane / acrylate, and acrylate / acrylonitrile.

[0104] The emulsion composition of the present invention may contain additives to the extent that the additives do not impair the performance of the liquid crystal device produced using the emulsion composition. Specific examples of the additives include surfactants, emulsifiers, dispersants, anti-settling agents, film-forming aids, leveling agents, light stabilizers, antioxidants, thickeners, polymerization inhibitors, photosensitizers, adhesives, antifoaming agents, water-soluble dyes, chiral agents, etc.

[0105] From the viewpoint of the transparency of the resulting liquid crystal device, the size of the liquid crystal composition is preferably an average particle size of 2 μm or more, more preferably 5 μm or more. Also, it is preferably 50 μm or less, more preferably 30 μm or less. When the average particle size is equal to or greater than the above-mentioned lower limit, the light scattering of the resulting liquid crystal-polymer composite film tends to be weaker, and the haze in the transparent state tends to be smaller. At the same time, the light scattering of the colored liquid crystal-polymer composite film also tends to be weaker, which relatively improves the contribution of the dichroic dye to light absorption, enabling more transparent control of the total light transmittance. When the average particle size is equal to or less than the above-mentioned upper limit, the granularity of the liquid crystal composition tends to disappear, and the resulting liquid crystal device tends to have a more uniform appearance.

[0106] On the other hand, from the viewpoint of the light-blocking properties of the resulting liquid crystal device, the average particle size of the liquid crystal composition is preferably 0.01 μm or more, more preferably 0.1 μm or more. It is also preferably less than 2 μm, more preferably 1 μm or less. When the average particle size is less than the above upper limit, the resulting liquid crystal-polymer composite film tends to exhibit strong light scattering, resulting in a large haze in the light-blocking state and a wide dynamic range (the difference in haze between the colored state and the transparent state). At the same time, the dichroic dye tends to absorb more light due to multiple scattering, resulting in a lower total light transmittance and a wide dynamic range (the difference in total light transmittance between the colored state and the transparent state). However, if the average particle size is smaller than the above lower limit (significantly smaller than the wavelength of visible light), the effect is diminished. Therefore, it is preferable that the average particle size of the liquid crystal composition is equal to or greater than the above lower limit.

[0107] The above average particle size is a median diameter based on the number of particles. The shape and average particle size of the liquid crystal composition are as described above for the liquid crystal composition of the present invention.

[0108] In the emulsion composition of the present invention, when the total mass of the polymers dispersed or dissolved in the medium is taken as 1, the total mass of the liquid crystal composition is preferably 0.5 or more, more preferably 1 or more. Also, it is preferably 4 or less, more preferably 3 or less. When the total mass of the liquid crystal composition relative to the total mass of the polymers is at least the above lower limit, the haze in the transparent state of a liquid crystal device obtained using the emulsion composition of the present invention tends to be low, and the driving voltage tends to be low. When the total mass of the liquid crystal composition relative to the total mass of the polymers is at most the above upper limit, the impact resistance and adhesion of a liquid crystal device obtained using the emulsion composition of the present invention tends to be improved.

[0109] [Liquid crystal component] The liquid crystal component contained in the liquid crystal composition is not particularly limited, and examples thereof include the liquid crystal component used in the liquid crystal element of the present invention described above. The dielectric anisotropy (Δε) of the liquid crystal component is positive. In this case, the liquid crystal is in a colored state when no voltage is applied, and in a transparent state when voltage is applied, which is the normal mode.

[0110] Furthermore, the NI point (nematic phase-isotropic phase transition temperature) of the liquid crystal component is 110°C or higher and 150°C or lower, and preferably 120°C or higher and 140°C or lower. If the NI point is above the lower limit, the dynamic range of transmittance change tends to be maintained even when continuously driven at a high temperature of about 90°C. Furthermore, the higher the NI point, the wider the dynamic range of transmittance change tends to be. On the other hand, as the NI point increases, the lower limit of the temperature of the nematic phase also tends to increase, so from the viewpoint of operation at low temperatures, the NI point is preferably below the upper limit. The method for measuring the NI point of the liquid crystal composition is as described above.

[0111] The refractive index anisotropy (Δn) of the liquid crystal component is 0.01 or more, preferably 0.02 or more, and more preferably 0.03 or more. It is also preferably 0.1 or less, and 0.10 or less. When Δn is equal to or less than the upper limit, light scattering at the interface between the polymer matrix and the liquid crystal composition tends to be reduced, and haze in the transparent state tends to be reduced. On the other hand, when Δn is equal to or more than the lower limit, the order parameter of the liquid crystal composition tends to be large. The method for measuring the refractive index anisotropy of the liquid crystal component is as described above.

[0112] The liquid crystal contained in the liquid crystal component may be nematic liquid crystal, cholesteric liquid crystal, smectic liquid crystal, or the like. Considering low cost, nematic liquid crystal or cholesteric liquid crystal is preferred. Furthermore, a chiral agent may be added to nematic liquid crystal to form cholesteric liquid crystal (chiral nematic liquid crystal). When cholesteric liquid crystal (chiral nematic liquid crystal) is used, the reciprocal (1 / p) of the chiral pitch p [μm] is preferably 0.01 to 0.5 [ / μm], and more preferably 0.01 to 0.3 [ / μm]. If the reciprocal of the chiral pitch is equal to or greater than the lower limit, the light absorption efficiency of the dichroic dye is increased, improving the light-blocking properties in the colored state. If the reciprocal of the chiral pitch is equal to or less than the upper limit, voltage increase can be suppressed.

[0113] Specific examples of known liquid crystal substances used as the liquid crystal component are as described above in the description of the liquid crystal component of the present invention, and specific exemplary compounds thereof are also as described above.

[0114] [Dichroic dye] The dichroic dye contained in the liquid crystal composition is not particularly limited, and examples thereof include the dichroic dyes used in the liquid crystal element of the present invention described above. Among them, it is preferable to contain an anthraquinone dye and / or an azo dye, since these tend to have a large absorption coefficient, a high solubility in the liquid crystal, and high light resistance. The dichroic dye may be one kind or a mixture of two or more kinds. Although there is no particular limitation, it is preferable that the dichroic dye contains an anthraquinone-based and / or azo-based dye in an amount of 20 mass % or more, and more preferably 50 mass % or more.

[0115] Although not particularly limited, the content of the dichroic dye relative to 100% by mass of the liquid crystal composition is preferably 0.1% by mass or more, more preferably 1% by mass or more, and even more preferably 3% by mass or more, and is preferably 20% by mass or less, more preferably 15% by mass or less, and even more preferably 10% by mass or less, relative to 100% by mass of the liquid crystal composition. When the content of the dichroic dye is equal to or greater than the lower limit, the liquid crystal device obtained using the emulsion composition of the present invention tends to exhibit greater light absorption in the colored state and a smaller amount of transmitted light.When the content of the dichroic dye is equal to or less than the upper limit, separation or precipitation of the dichroic dye is less likely to occur, and the reliability of the liquid crystal device tends to be improved.

[0116] [Method for producing emulsion composition] The method for producing the emulsion composition of the present invention is not particularly limited, but it can be produced, for example, by the following method. Manufacturing method (1) A liquid crystal composition as an oil phase and a water-containing medium as an aqueous phase are mixed, and after an emulsification process, a liquid in which a polymer is dispersed or dissolved in the water-containing medium is added. Production method (2) A liquid crystal composition as an oil phase and a liquid in which a polymer is dispersed or dissolved are mixed with a medium containing water as an aqueous phase, and an emulsification step is carried out. Manufacturing method (3) A powder or slurry of microencapsulated liquid crystal, in which the peripheral portion of the liquid crystal composition is encapsulated with a polymer, a silica compound, inorganic nanoparticles, etc., is mixed with a medium containing water, and after a dispersion process, a liquid in which the polymer is dispersed or dissolved is added to the medium containing water. Production method (4) A dispersion step is carried out by mixing the powder or slurry of the microcapsule liquid crystal with a liquid in which a polymer is dispersed or dissolved in a medium containing water.

[0117] Among these, production methods (1) and (3) are preferred because they allow the emulsification step or dispersion step to be carried out while the mixture is in a low viscosity state, making production possible with low energy consumption, and furthermore, making it easy to control the particle size of the liquid crystal composition.

[0118] As the liquid in which a polymer is dispersed or dissolved in a medium containing water, commercially available aqueous resin emulsions can be used. Specific examples thereof are shown below. Water-based urethane emulsion: DSM NeoRez R-9660, NeoRez R-972, NeoRez R-9637, NeoRez R-9679, NeoRez R-960, NeoRez R-2170, NeoRez R-966, NeoRez R-967, NeoRez R-986, NeoRez R-9603, NeoRez R-4000, NeoRez R-9404, NeoRez R-600, NeoRez R-650, NeoRez R-1010; Daiichi Kogyo Seiyaku Superflex 126, Superflex 130, Superflex 150, Superflex 150HS, Superflex 170, Superflex 210, Superflex 300, Superflex 420, Superflex 420NS, Superflex 460, Superflex 460S, Superflex 470, Superflex 500M, Superflex 620, Superflex 650, Superflex 740, Superflex 820, Superflex 830HS, Superflex 860, Superflex 870, Superflex E-2000, Superflex E-4800; Nicca Chemical Co., Ltd. Neosticker 200, Neosticker 400, Neosticker 700, Neosticker 1200, Neosticker X-7096, Evafanol HA-107C, Evafanol HA-50C, Evafanol HA-170, Evafanol HA-560, Evafanol HA-15, Evafanol AP-12, Evafanol APC-55. Water-based acrylic emulsion: NeoCryl A-633, NeoCryl A-639, NeoCryl A-655, NeoCryl A-662, NeoCryl A-1091, NeoCryl A-1092, NeoCryl A-1093, NeoCryl A-1094, NeoCryl A-2091, NeoCryl A-2092, NeoCryl A-6016, NeoCryl A-6057, NeoCryl A-6069, NeoCryl A-6092, NeoCryl A-614, NeoCryl A-550, NeoCryl A-1105, NeoCryl A-1125, NeoCryl A-1127, NeoCryl XK-12, NeoCryl XK-16, NeoCryl XK-30, NeoCryl XK-36, NeoCryl XK-52, NeoCryl XK-190, NeoCryl XK-188, NeoCryl XK-240;Japan Coating Resin Co., Ltd. Ricabond 702, Ricabond 727, Ricabond 743N, Ricabond 745, Ricabond 752, Ricabond 801, Ricabond 940, Ricabond 972, Ricabond 1711, Ricabond 1752, Ricabond 6520, Ricabond 6720, Ricabond 7110, Ricabond 7180, Ricabond 7525, Ricabond 7820, Ricabond 8020, Ricabond 8030, Ricabond DM60, Ricabond DM772, Ricabond DM774, Ricabond LDM6740, Ricabond LDM7522, Ricabond LDM7523, Ricabond ES-65, Rikabond ES-90, Rikabond ES-620, Rikabond ET-700, Rikabond ET-831, Rikabond HS-5, Rikabond HS-531, Rikabond AP-601, Rikabond AP-96, Rikabond AP-620, Rikabond AP-700, Rikabond AP-80, Rikabond 710A, Rikabond 730L, Rikabond 731L, Rikabond 952B, Rikabond 966A, Rikabond 7320, Rikabond 7400, Rikabond FK-420, Rikabond FK-64S, Rikabond FK-66IS, FK-66N, FK-68H, Rikabond FK-471, Rikabond FK-475, Rikabond FK-489, Rikabond FK-284, Rikabond FK-600S, Rikabond FK-3830, Rikabond FK-3840, Rikabond FK-6100, Mowinyl VDM7410, Mowinyl 4061, Mowinyl 4080, Mowinyl 4090, Mowinyl 4050, Mowinyl S-71, Mowinyl 461, Mowinyl 650, Mowinyl AP-60L, Mowinyl 490; ThreeBond 1549, ThreeBond 1549B, ThreeBond 1555C, ThreeBond 1555D;

[0119] Among these, NeoRez R-966, NeoRez R-967, NeoCryl A-1125, NeoCryl A-1127, Rikabond FK-471, Rikabond ES-620, Rikabond LDM7522, Mowinyl 4061, Mowinyl 4080, Mowinyl 4090, and ThreeBond 1549 are preferred because they have excellent dispersion stability of the oil phase.

[0120] To obtain a stable emulsion, it is preferable to add a surfactant or dispersion stabilizer before the emulsification or dispersion step. The surfactant is not particularly limited, and may be ionic or nonionic, low molecular weight or high molecular weight, and non-reactive or reactive.

[0121] The amount of surfactant added is not particularly limited, but is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, relative to the liquid crystal composition. Also, it is preferably 20% by mass or less, more preferably 10% by mass or less. By adding the surfactant in the above range, the dispersion of the emulsion tends to be stabilized, and the particle size of the liquid crystal composition tends to be controlled within a desired range.

[0122] The surfactant may be added to the liquid crystal composition or to a medium containing water depending on the solubility.

[0123] Examples of surfactants include the following: anionic surfactants such as carboxylates, sulfonates, sulfates, and phosphates; Cationic surfactants such as amine salts and quaternary ammonium salts; amphoteric surfactants such as alkylamino fatty acid salts, alkylamine oxides, betaines, sulfobetaines, amidosulfobetaines, carbobetaines, and imidazolines; Ether types such as polyoxyethylene alkyl ethers, polyoxyethylene alkylaryl ethers, polyoxyethylene aralkyl ethers, polyoxyethylene aralkylaryl ethers, polyoxyethylene polyoxypropylene block adducts, alkyl glucosides, and polyether-modified silicones; ester types such as glycerin fatty acid esters, sorbitan fatty acid esters, and sucrose fatty acid esters; ester-ether types such as polyoxyethylene fatty acid esters, polyoxyethylene sorbitan fatty acid esters, and polyoxyethylene sucrose fatty acid esters; acetyl types such as acetyl-modified polyvinyl alcohol; and nonionic surfactants such as fatty acid alkanolamides.

[0124] Among these, anionic surfactants are preferred because of their high water solubility and dispersion stability, and sulfonates are particularly preferred. Nonionic surfactants are also preferred because they tend to improve the electrical reliability of liquid crystal elements. Among these, ether or ester surfactants are preferred, and polyoxyethylene alkyl ethers, polyoxyethylene alkylaryl ethers, polyoxyethylene aralkyl ethers, polyoxyethylene aralkylaryl ethers, polyoxyethylene polyoxypropylene block adducts, etc. are particularly preferred.

[0125] The dispersion stabilizer is not particularly limited, but examples include the following: Polymers such as polyvinyl alcohol, polyvinylpyrrolidone, methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropylmethyl cellulose, polyethylene glycol, polyacrylic acid, polymethacrylic acid, polyurethane, polyamine, polyamide, polyether, maleic acid copolymer, gelatin, starch, chitosan, corn starch, and modified products thereof; Copolymers such as methacrylate / acrylonitrile, urethane / acrylate, and acrylate / acrylonitrile; Inorganic oxide particles such as silica particles, titania particles, and alumina particles: Among these, polyvinyl alcohol and its modified products, polyurethane, polyamide, etc. are preferred because of their high dispersion stability. Examples of dispersion stabilizers include those exemplified as polymers constituting the polymer matrix, and when they are contained in an emulsion composition or a liquid crystal-polymer composite film, they are included as polymers constituting the polymer matrix.

[0126] The saponification degree of polyvinyl alcohol is preferably 80 mol% or more, more preferably 85 mol% or more, and is preferably 95 mol% or less, more preferably 91 mol% or less. When the saponification degree is within these ranges, the solubility in a water-containing medium tends to be high. The degree of polymerization of polyvinyl alcohol is preferably at least 100, more preferably at least 300. Also, it is preferably at most 2500, more preferably at most 1000. When the degree of polymerization is within these ranges, the film tends to have excellent flexibility.

[0127] Specific examples of polyvinyl alcohol include Gohsenol GL-03, Gohsenol GL-05, Gohsenol GM-14L, Gohsenol GM14, Gohsenol GH-17, Gohsenol GH-17R, Gohsenol GH-20, Gohsenol GH-23, Gohsenol AL-06, Gohsenol P-610, and Gohsenol C-500, all manufactured by Nippon Synthetic Chemical Industry Co., Ltd.; Kuraray Poval 25-88KL, Kuraray Poval 32-97KL, Kuraray Poval 3-86SD, Kuraray Poval 105-88KX, and Kuraray Poval 200-88KX, all manufactured by Kuraray Co., Ltd.; and Denka Poval H-12, Denka Poval H-17, Denka Poval H-24, Denka Poval B-05, and Denka Poval Examples include Denka Poval B-17, Denka Poval B-20, Denka Poval B-24, and Denka Poval B-33.

[0128] In producing the emulsion composition, the emulsification method and dispersion method are not particularly limited, and examples thereof include a method of mechanically crushing particles using a stirrer, homogenizer, homomixer, disperser, high-pressure emulsifier, blender, colloid mill, ultrasonic disperser, etc.; and a method of extruding a liquid through pores using a porous membrane, microchannel, inkjet, etc.

[0129] Among the above methods, when producing an emulsion composition having an average particle size of 2 μm to 50 μm, a method of extruding a liquid through pores using a porous membrane (membrane emulsification method) is preferred because it allows precise control of the particle size distribution and is easy to produce. There are no particular restrictions on the porous membrane, but shirasu porous glass, etc. can be used.

[0130] When producing an emulsion composition having an average particle size of the liquid crystal composition of 0.01 μm or more and less than 2 μm, a uniform emulsion composition can be easily produced by first producing an emulsion composition having an average particle size of the liquid crystal composition of 2 μm or more and 50 μm or less using a membrane emulsification method or the like, and then mechanically crushing the particles using a high-pressure emulsifier or an ultrasonic disperser.

[0131] A crosslinking agent may be used in the emulsion composition as appropriate. The use of a crosslinking agent tends to improve the water resistance and impact resistance of the liquid crystal-polymer composite film.

[0132] The crosslinking agent is not particularly limited, but examples thereof include the following: Epoxy compounds such as ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, glycerol diglycidyl ether, polyglycerin polyglycidyl ether, and diglycidylaniline; epoxysilane compounds such as γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyldimethoxymethylsilane, γ-glycidoxypropyldiethoxymethylsilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and β-(3,4-epoxycyclohexyl)ethyltriethoxysilane; aminosilane compounds such as 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, and N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane; mercaptosilane compounds such as γ-mercaptopropyltrimethoxysilane; hydrazide compounds such as carbodihydrazide, oxalic acid dihydrazide, adipic acid dihydrazide, sebacic acid dihydrazide, and isophthalic acid dihydrazide; Semicarbazide resin; Polycarbodiimide resins; Aziridine-based (ethyleneimino group-containing) compounds such as tetramethylolmethane-tris(β-aziridinylpropionate), trimethylolpropane-tris(β-aziridinylpropionate), methylenebis[N-(1-aziridinylcarbonyl)-4-aniline], N,N'-hexamethylenebis(1-aziridinecarboxamide), and N,N'-hexaaminoethylene-1,6-bis(1-aziridinecarboxamide); Acetoacetoxy group-containing compounds;Oxazoline group-containing compounds; Polyethylene polyamine; Polyethylene imine; Polyamide polyamine; Polyamide polyurea; Alkylated polymethylol melamine; Glyoxal; Water-dispersible isocyanates; Blocked isocyanates; Carbodiimide-containing compounds; Bisvinyl sulfones; Lactic titanates:

[0133] When an epoxy compound or an epoxysilane compound is used, a catalyst such as an imidazole compound, an amine compound, or a phosphorus compound may be added.

[0134] Among the above, hydrazide compounds, oxazoline group-containing compounds, carbodiimide group-containing compounds, and blocked isocyanates are preferred because they have a high crosslinking rate and low toxicity.

[0135] While any combination of polymer and crosslinking agent can be used, combinations of polyurethane and oxazoline group-containing compound, polyurethane and carbodiimide group-containing compound, polyurethane and blocked isocyanate, and polyacrylic and hydrazide compound are preferred because they have high crosslinking reactivity. Also, from the viewpoint of the stability of the resulting emulsion composition, a combination of polyacrylic and carbodiimide group-containing compound is preferred.

[0136] The amount of crosslinking agent added is not particularly limited, but is preferably 0.1% by mass or more, more preferably 1% by mass or more, based on the polymer to be crosslinked. Also, it is preferably 20% by mass or less, more preferably 10% by mass or less. By adding the crosslinking agent in the above range, the water resistance and impact resistance of the liquid crystal-polymer composite film tend to be improved, and flexibility tends to be maintained. The timing of adding the crosslinking agent may be a one-component type in which the crosslinking agent is added to the emulsion composition from the beginning, or a two-component type in which the crosslinking agent is added just before application to the substrate.

[0137] The viscosity of the emulsion composition of the present invention is preferably 10 mPa·s or more, more preferably 100 mPa·s or more, and preferably 10,000 mPa·s or less, more preferably 2,000 mPa·s or less. When the viscosity is within the above range, it becomes easy to apply a liquid crystal-polymer composite film with a uniform thickness, and the application speed can be increased, which tends to increase productivity.

[0138] In order to keep the viscosity of the emulsion composition of the present invention within the above range, a viscosity adjuster such as a thickener, a thixotropic agent, or a viscosity reducer may be used.

[0139] The viscosity modifier is not particularly limited, but may be any of those exemplified as dispersion stabilizers.

[0140] The content of the liquid crystal composition in the emulsion composition is preferably 20% by mass or more, more preferably 30% by mass or more, and preferably 70% by mass or less, more preferably 65% by mass or less. When the content of the liquid crystal composition is within the above range, repelling that occurs when the emulsion composition is applied to a substrate is suppressed, and it tends to be easier to keep the particle size and viscosity of the liquid crystal composition within the above ranges.

[0141] The particle size of the polymer used in the emulsion composition is preferably 1 nm or more, more preferably 10 nm or more, and is preferably 1000 nm or less, more preferably 200 nm or less. By keeping the particle size within the above range, it tends to be easier to keep the viscosity of the emulsion composition within the above range.

[0142] The molecular weight of the polymer is 1.0 × 10 3 More than 1.0×10 is preferable. 4 More preferably, 1.0×10 6 Less than 1.0 x 10 is preferable. 5 The following is more preferable: When the molecular weight of the polymer is within the above range, it tends to be easier to keep the viscosity of the emulsion composition within the above range. [Example]

[0143] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples as long as the gist of the present invention is not exceeded.

[0144] [Example 1] A nematic liquid crystal with Δn=0.09 and an NI point=125°C was used as the liquid crystal component. To this was mixed an anthraquinone-based cyan dichroic dye represented by (D-1) below, an azo-based yellow dichroic dye represented by (D-2) below, and an azo-based magenta dichroic dye NKX-3739 manufactured by Hayashibara Co., Ltd. and a chiral agent (CB-15) in the following proportions, and the dichroic dyes were dissolved to obtain a black liquid crystal composition (L-1).

[0145] [ka]

[0146] <Liquid crystal composition formulation> Nematic liquid crystal: 92.0% by mass D-1: 3.4% by mass D-2: 0.6% by mass NKX-3739: 1.0% by mass CB-15: 3.0% by mass Dichroic dye content relative to 100% by mass of liquid crystal composition: 5% by mass

[0147] A 1.5% by mass aqueous solution of sodium dodecylbenzenesulfonate was added to 50% by mass of the liquid crystal composition (L-1), and emulsified by passing through a shirasu porous glass to obtain an o / w emulsion (E-1). A white latex (W-1) was obtained by adding 7% by mass of polyvinyl alcohol Gohsenol GH-17R (Mitsubishi Chemical Corporation) to 93% by mass of an aqueous acrylic emulsion Rikabond ES-620 (Japan Coating Resins Co., Ltd.) and stirring. To 55 parts by mass of the o / w emulsion (E-1), 45 parts by mass of the white latex (W-1) was added, and the mixture was stirred until homogenized to obtain an emulsion composition (I-1).

[0148] The average particle size of the liquid crystal composition in emulsion composition (I-1) was 10 μm. When the mass of the polymer (P-1) dispersed or dissolved in the aqueous phase in emulsion composition (I-1) was taken as 1, the mass of the liquid crystal composition (L-1) was 1.14.

[0149] The substrate was a 125 μm thick PET film with a transparent ITO electrode formed on it. The emulsion composition (I-1) was applied to the ITO film on the substrate using a bar coater and dried at 50°C to obtain a liquid crystal-polymer composite film with a thickness of 30 μm. When the liquid crystal-polymer composite film was observed from above with a microscope, it was found that the liquid crystal composition with an average particle size of 10 μm was dispersed in the polymer matrix. The film substrate on which the liquid crystal-polymer composite film was formed was bonded to another substrate at 80°C, facing each other, to obtain a liquid crystal element (F-1). The liquid crystal element (F-1) was flexible and could be cut with scissors to shape. In other words, this liquid crystal element (F-1) could be cut and shaped.

[0150] The liquid crystal element (F-1) exhibited normal mode operation, coloring black when the voltage was off and becoming transparent when the voltage was on (rectangular wave of 100 Hz and 50 Vrms). When the voltage was off, the haze was 70.3% and the total light transmittance was 23.9%. When a voltage of 100 Vrms was applied, the haze was 9.6% and the total light transmittance was 54.5%.

[0151] [Example 2] A black liquid crystal composition (L-2) was obtained by mixing in the same manner as in Example 1, except that a nematic liquid crystal with Δn=0.08 and an NI point=140° C. was used as the liquid crystal component. A 1.5% by mass aqueous solution of sodium dodecylbenzenesulfonate was added to 50% by mass of the liquid crystal composition (L-2), and emulsified by passing through a shirasu porous glass to obtain an o / w emulsion (E-2). To 55 parts by mass of the o / w emulsion (E-2), 45 parts by mass of the white latex (W-1) was added, and the mixture was stirred until homogenous to obtain an emulsion composition (I-2). The average particle size of the liquid crystal composition in emulsion composition (I-2) was 10 μm. When the mass of the polymer (P-1) dispersed or dissolved in the aqueous phase in emulsion composition (I-2) was 1, the mass of liquid crystal composition (L-2) was 1.15.

[0152] A liquid crystal element (F-2) was obtained in the same manner as in Example 1 using emulsion composition (I-2). When the liquid crystal-polymer composite film of the liquid crystal element (F-2) was observed from above with a microscope, it was found that the liquid crystal composition had an average particle size of 10 μm dispersed in the polymer matrix. The liquid crystal element (F-2) was flexible and could be cut with scissors to shape. In other words, this liquid crystal element (F-2) could be cut and shaped. The liquid crystal element (F-2) exhibited normal mode operation, coloring black when the voltage was off and becoming transparent when the voltage was on (rectangular wave of 100Hz / 50Vrms). When the voltage was off, the haze was 72.8% and the total light transmittance was 25.2%. When a voltage of 100Vrms was applied, the haze was 15.8% and the total light transmittance was 55.2%.

[0153] [Comparative Example 1] A black liquid crystal composition (L-3) was obtained in the same manner as in Example 1, except that a nematic liquid crystal having Δn=0.08 and an NI point=96° C. was used as the liquid crystal component. A 1.5% by mass aqueous solution of sodium dodecylbenzenesulfonate was added to 50% by mass of the liquid crystal composition (L-3), and emulsified by passing through a shirasu porous glass to obtain an o / w emulsion (E-3). To 55 parts by mass of the o / w emulsion (E-3), 45 parts by mass of the white latex (W-1) was added, and the mixture was stirred until homogenized to obtain an emulsion composition (I-3). The average particle size of the liquid crystal composition in emulsion composition (I-3) was 10 μm. When the mass of the polymer (P-1) dispersed or dissolved in the aqueous phase in emulsion composition (I-3) was taken as 1, the mass of liquid crystal composition (L-3) was 1.14.

[0154] A black liquid crystal element (F-3) was obtained using emulsion composition (I-3) in the same manner as in Example 1. When the liquid crystal-polymer composite film of the liquid crystal element (F-3) was observed from above with a microscope, it was found that the liquid crystal composition had an average particle size of 10 μm dispersed in the polymer matrix. The liquid crystal element (F-3) was flexible and could be cut with scissors to shape. In other words, this liquid crystal element (F-3) could be cut and shaped. The liquid crystal element (F-3) exhibited normal mode operation, coloring black when the voltage was off and becoming transparent when the voltage was on (rectangular wave of 100 Hz and 50 Vrms). When the voltage was off, the haze was 72.0% and the total light transmittance was 19.1%. When a voltage of 100 Vrms was applied, the haze was 9.5% and the total light transmittance was 46.7%.

[0155] [Example 3] The liquid crystal element (F-1) obtained in Example 1 was placed in a thermostatic chamber at 90°C and continuously driven by applying a square wave with a frequency of 100 Hz and 50 Vrms. After 65, 133, and 228 hours of continuous driving, the element was removed and returned to room temperature, and the haze and total light transmittance were measured in the same manner as in Example 1. The difference between the ON and OFF values (dynamic range) was designated as ΔHaze and ΔTT, and no significant changes were observed from the initial values. The results are shown in Table 1 below.

[0156] [Table 1]

[0157] [Example 4] The liquid crystal element (F-2) obtained in Example 2 was placed in a thermostatic chamber at a temperature of 90° C., and a rectangular wave with a frequency of 100 Hz and 50 Vrms was applied to perform continuous driving in the same manner as in Example 3. Continuous operation began, and the panels were removed after 65 hours, 133 hours, and 228 hours, returned to room temperature, and the haze and total light transmittance were measured. The difference between the ON and OFF states, ΔHaze and ΔTT, showed no significant changes from the initial values. The results are shown in Table 2 below.

[0158] [Table 2]

[0159] Comparative Example 2 The liquid crystal element (F-3) obtained in Comparative Example 1 was placed in a thermostatic chamber at a temperature of 90° C., and a rectangular wave with a frequency of 100 Hz and 50 Vrms was applied to perform continuous driving in the same manner as in Example 3. Continuous operation began, and the panel was removed after 65 hours, 133 hours, and 228 hours, returned to room temperature, and the haze and total light transmittance were measured. The difference between the ON and OFF states, ΔHaze and ΔTT, showed a significant decrease from 65 hours onwards. The results are shown in Table 3 below.

[0160] [Table 3]

[0161] 1 and 2 show the haze (dynamic range ΔHaze) and total light transmittance (dynamic range ΔTT) after 65 hours, 133 hours, and 228 hours from the start of continuous driving in Examples 3 and 4 and Comparative Example 2. The above examples and comparative examples show that when the NI point of the liquid crystal component is within a specific range, the liquid crystal element has a large change range (dynamic range) in visible light transmittance, and the dynamic range is maintained even after operation at high temperatures.

[0162] [Example 5] The o / w emulsion (E-1) prepared in Example 1 was subjected to ultrasonic dispersion for 10 minutes using an ultrasonic disperser (UH-600) manufactured by SMT Corporation to obtain an o / w emulsion (E-5). To 55 parts by mass of the o / w emulsion (E-5), 45 parts by mass of the white latex (W-1) was added, and the mixture was stirred until homogenized to obtain an emulsion composition (I-5). The average particle size of the liquid crystal composition in emulsion composition (I-5) was 0.2 μm. In emulsion composition (I-5), the mass of the polymer (P-1) dispersed or dissolved in the aqueous phase was 1, and the mass of the liquid crystal composition (L-1) was 1.14.

[0163] A liquid crystal element (F-5) was obtained in the same manner as in Example 1 using emulsion composition (I-5). When the liquid crystal-polymer composite film of the liquid crystal element (F-5) was observed from above with a microscope, it was found that the liquid crystal composition had an average particle size of 0.2 μm dispersed in the polymer matrix. The liquid crystal element (F-5) was flexible and could be cut with scissors to shape. In other words, this liquid crystal element (F-5) could be cut and shaped. The liquid crystal element (F-5) exhibited normal mode operation, coloring black when the voltage was off and becoming transparent when the voltage was on (rectangular wave of 100 Hz and 50 Vrms). When the voltage was off, the haze was 74.0% and the total light transmittance was 22.7%. When a voltage of 100 Vrms was applied, the haze was 5.7% and the total light transmittance was 66.3%.

[0164] [Example 6] The o / w emulsion (E-2) prepared in Example 2 was subjected to ultrasonic dispersion for 10 minutes using an ultrasonic disperser (UH-600) manufactured by SMT Corporation to obtain an o / w emulsion (E-6). To 55 parts by mass of the o / w emulsion (E-6), 45 parts by mass of the white latex (W-1) was added, and the mixture was stirred until homogenized to obtain an emulsion composition (I-6). The average particle size of the liquid crystal composition in emulsion composition (I-6) was 0.2 μm. In emulsion composition (I-6), the mass of the polymer (P-1) dispersed or dissolved in the aqueous phase was 1, and the mass of the liquid crystal composition (L-2) was 1.16.

[0165] A liquid crystal element (F-6) was obtained in the same manner as in Example 1 using emulsion composition (I-6). When the liquid crystal-polymer composite film of the liquid crystal element (F-6) was observed from above with a microscope, it was found that the liquid crystal composition had an average particle size of 0.2 μm dispersed in the polymer matrix. The liquid crystal element (F-6) was flexible and could be cut with scissors to shape. In other words, this liquid crystal element (F-6) could be cut and shaped. The liquid crystal element (F-6) exhibited normal mode operation, coloring black when the voltage was off and becoming transparent when the voltage was on (rectangular wave of 100 Hz and 50 Vrms). When the voltage was off, the haze was 67.7% and the total light transmittance was 25.8%. When a voltage of 100 Vrms was applied, the haze was 8.8% and the total light transmittance was 59.8%.

[0166] Comparative Example 3 The o / w emulsion (E-3) prepared in Comparative Example 1 was subjected to ultrasonic dispersion for 10 minutes using an ultrasonic disperser (UH-600) manufactured by SMT Corporation to obtain an o / w emulsion (E-7). To 55 parts by mass of the o / w emulsion (E-7), 45 parts by mass of the white latex (W-1) was added, and the mixture was stirred until homogenous, to obtain an emulsion composition (I-7). The average particle size of the liquid crystal composition in emulsion composition (I-7) was 0.2 μm. When the mass of the polymer (P-1) dispersed or dissolved in the aqueous phase in emulsion composition (I-7) was taken as 1, the mass of the liquid crystal composition (L-3) was 1.14.

[0167] A black liquid crystal element (F-7) was obtained using emulsion composition (I-7) in the same manner as in Example 1. When the liquid crystal-polymer composite film of the liquid crystal element (F-7) was observed from above with a microscope, it was found that the liquid crystal composition had an average particle size of 0.2 μm dispersed in the polymer matrix. The liquid crystal element (F-7) was flexible and could be cut with scissors to shape. In other words, this liquid crystal element (F-7) could be cut and shaped. The liquid crystal element (F-7) exhibited normal mode operation, coloring black when the voltage was off and becoming transparent when the voltage was on (rectangular wave of 100 Hz and 50 Vrms). When the voltage was off, the haze was 59.6% and the total light transmittance was 27.1%. When a voltage of 100 Vrms was applied, the haze was 8.4% and the total light transmittance was 54.4%.

[0168] [Example 7] The liquid crystal element (F-5) obtained in Example 5 was placed in a thermostatic chamber at 90°C and continuously driven by applying a square wave with a frequency of 100 Hz and 50 Vrms. After 65, 133, and 228 hours of continuous driving, the element was removed and returned to room temperature, and the haze and total light transmittance were measured in the same manner as in Example 1. The difference between the ON and OFF values (dynamic range) was designated ΔHaze and ΔTT, and no significant changes were observed from the initial values. The results are shown in Table 4 below.

[0169] [Table 4]

[0170] [Example 8] The liquid crystal element (F-6) obtained in Example 6 was placed in a thermostatic chamber at a temperature of 90° C., and a rectangular wave with a frequency of 100 Hz and 50 Vrms was applied to perform continuous driving in the same manner as in Example 7. Continuous operation began, and the panels were removed after 65 hours, 133 hours, and 228 hours, returned to room temperature, and the haze and total light transmittance were measured. The difference between the ON and OFF states, ΔHaze and ΔTT, showed no significant changes from the initial values. The results are shown in Table 5 below.

[0171] [Table 5]

[0172] Comparative Example 4 The liquid crystal element (F-7) obtained in Comparative Example 3 was placed in a thermostatic chamber at a temperature of 90° C., and a square wave with a frequency of 100 Hz and 50 Vrms was applied to perform continuous driving in the same manner as in Example 7. Continuous operation began, and the panels were removed after 65 hours, 133 hours, and 228 hours, returned to room temperature, and the haze and total light transmittance were measured. The difference between the ON and OFF states, ΔHaze and ΔTT, showed a significant decrease from 65 hours onwards. The results are shown in Table 6 below.

[0173] [Table 6]

[0174] The haze (dynamic range ΔHaze) and total light transmittance (dynamic range ΔTT) of Examples 7 and 8 and Comparative Example 4 after 65 hours, 133 hours, and 228 hours from the start of continuous driving are shown in FIGS. The above examples and comparative examples show that when the NI point of the liquid crystal component is within a specific range, the liquid crystal element has a large change range (dynamic range) in visible light transmittance, and the dynamic range is maintained even after operation at high temperatures.

[0175] [Example 9] A black liquid crystal composition (L-8) was obtained by mixing in the same manner as in Example 1, except that a nematic liquid crystal with Δn=0.096 and an NI point=130.6° C. was used as the liquid crystal component. A 1.5% by mass aqueous solution of sodium dodecylbenzenesulfonate was added to 50% by mass of the liquid crystal composition (L-8), and emulsified by passing through a shirasu porous glass to obtain an o / w emulsion (E-8). To 55 parts by mass of the o / w emulsion (E-8), 45 parts by mass of the white latex (W-1) was added, and the mixture was stirred until homogenous, to obtain an emulsion composition (I-8). The average particle size of the liquid crystal composition in emulsion composition (I-8) was 10 μm. When the mass of the polymer (P-1) dispersed or dissolved in the aqueous phase in emulsion composition (I-8) was 1, the mass of liquid crystal composition (L-8) was 1.17.

[0176] A liquid crystal element (F-8) was obtained using emulsion composition (I-8) in the same manner as in Example 1. When the liquid crystal-polymer composite film of the liquid crystal element (F-8) was observed from above with a microscope, it was found that the liquid crystal composition had an average particle size of 10 μm dispersed in the polymer matrix. The liquid crystal element (F-8) was flexible and could be cut with scissors to shape. In other words, this liquid crystal element (F-8) could be cut and shaped. The liquid crystal element (F-8) exhibited normal mode operation, coloring black when the voltage was off and becoming transparent when the voltage was on (rectangular wave of 100 Hz and 50 Vrms). When the voltage was off, the haze was 73.1% and the total light transmittance was 23.7%. When a voltage of 100 Vrms was applied, the haze was 7.2% and the total light transmittance was 56.3%.

[0177] [Example 10] A black liquid crystal composition (L-9) was obtained by mixing in the same manner as in Example 1, except that a nematic liquid crystal with Δn=0.095 and an NI point=129.5° C. was used as the liquid crystal component. A 1.5% by mass aqueous solution of sodium dodecylbenzenesulfonate was added to 50% by mass of the liquid crystal composition (L-9), and emulsified by passing through a shirasu porous glass to obtain an o / w emulsion (E-9). To 55 parts by mass of the o / w emulsion (E-9), 45 parts by mass of the white latex (W-1) was added, and the mixture was stirred until homogenous, to obtain an emulsion composition (I-9). The average particle size of the liquid crystal composition in emulsion composition (I-9) was 10 μm. When the mass of the polymer (P-1) dispersed or dissolved in the aqueous phase in emulsion composition (I-9) was 1, the mass of liquid crystal composition (L-9) was 1.25.

[0178] A liquid crystal element (F-9) was obtained using emulsion composition (I-9) in the same manner as in Example 1. When the liquid crystal-polymer composite film of the liquid crystal element (F-9) was observed from above with a microscope, it was found that the liquid crystal composition had an average particle size of 10 μm dispersed in the polymer matrix. The liquid crystal element (F-9) was flexible and could be cut with scissors to shape. In other words, this liquid crystal element (F-9) could be cut and shaped. The liquid crystal element (F-9) exhibited normal mode operation, coloring black when the voltage was off and becoming transparent when the voltage was on (rectangular wave of 100 Hz and 50 Vrms). When the voltage was off, the haze was 72.5% and the total light transmittance was 24.4%. When a voltage of 100 Vrms was applied, the haze was 7.6% and the total light transmittance was 57.3%.

[0179] Comparative Example 5 A black liquid crystal composition (L-10) was obtained by mixing in the same manner as in Example 1, except that a nematic liquid crystal with Δn=0.164 and an NI point=120.7° C. was used as the liquid crystal component. A 1.5% by mass aqueous solution of sodium dodecylbenzenesulfonate was added to 50% by mass of the liquid crystal composition (L-10), and emulsified by passing through a shirasu porous glass to obtain an o / w emulsion (E-10). To 55 parts by mass of the o / w emulsion (E-10), 45 parts by mass of the white latex (W-1) was added, and the mixture was stirred until homogenous to obtain an emulsion composition (I-10). The average particle size of the liquid crystal composition in emulsion composition (I-10) was 10 μm. When the mass of the polymer (P-1) dispersed or dissolved in the aqueous phase in emulsion composition (I-10) was 1, the mass of liquid crystal composition (L-10) was 1.17.

[0180] A liquid crystal element (F-10) was obtained using emulsion composition (I-10) in the same manner as in Example 1. When the liquid crystal-polymer composite film of the liquid crystal element (F-10) was observed from above with a microscope, it was found that the liquid crystal composition had an average particle size of 10 μm dispersed in the polymer matrix. The liquid crystal element (F-10) was flexible and could be cut with scissors to shape. In other words, this liquid crystal element (F-10) could be cut and shaped. The liquid crystal element (F-10) exhibited normal mode operation, coloring black when the voltage was off and becoming transparent when the voltage was on (rectangular wave of 100 Hz and 50 Vrms). When the voltage was off, the haze was 83.3% and the total light transmittance was 24.7%. When a voltage of 100 Vrms was applied, the haze was 18.2% and the total light transmittance was 58.0%.

[0181] Comparative Example 6 A black liquid crystal composition (L-11) was obtained by mixing in the same manner as in Example 1, except that a nematic liquid crystal with Δn=0.195 and an NI point=129.9° C. was used as the liquid crystal component. A 1.5% by mass aqueous solution of sodium dodecylbenzenesulfonate was added to 50% by mass of the liquid crystal composition (L-11), and emulsified by passing through a shirasu porous glass to obtain an o / w emulsion (E-11). To 55 parts by mass of the o / w emulsion (E-11), 45 parts by mass of the white latex (W-1) was added, and the mixture was stirred until homogenous to obtain an emulsion composition (I-11). The average particle size of the liquid crystal composition in emulsion composition (I-11) was 10 μm. When the mass of the polymer (P-1) dispersed or dissolved in the aqueous phase in emulsion composition (I-11) was taken as 1, the mass of liquid crystal composition (L-11) was 1.17.

[0182] A liquid crystal element (F-11) was obtained using emulsion composition (I-11) in the same manner as in Example 1. When the liquid crystal-polymer composite film of the liquid crystal element (F-11) was observed from above with a microscope, it was found that the liquid crystal composition had an average particle size of 10 μm dispersed in the polymer matrix. The liquid crystal element (F-11) was flexible and could be cut with scissors to shape. In other words, this liquid crystal element (F-11) could be cut and shaped. The liquid crystal element (F-11) exhibited normal mode operation, coloring black when the voltage was off and becoming transparent when the voltage was on (rectangular wave of 100 Hz and 50 Vrms). When the voltage was off, the haze was 84.3% and the total light transmittance was 26.6%. When a voltage of 100 Vrms was applied, the haze was 22.2% and the total light transmittance was 60.1%.

[0183] The dynamic range of haze and total light transmittance of the liquid crystal elements (F-10) and (F-11) prepared in Comparative Examples 5 and 6 was similar to that of Examples 9 and 10, but the haze was high when a voltage was applied, and they lacked transparency.

[0184] Although the present invention has been described in detail with reference to specific embodiments, it will be apparent to those skilled in the art that various modifications can be made without departing from the spirit and scope of the invention. This application is based on Japanese Patent Application No. 2021-31559, filed on March 1, 2021, the entire contents of which are incorporated by reference.

Claims

1. A liquid crystal element comprising two substrates with transparent conductive films arranged so that the transparent conductive films face each other, and a liquid crystal-polymer composite film sandwiched between the two substrates with transparent conductive films, the liquid crystal-polymer composite film has a polymer matrix and a liquid crystal composition surrounded by the polymer matrix, the liquid crystal composition contains a liquid crystal component and a dichroic dye; The liquid crystal component has a positive dielectric anisotropy and an NI point of 110° C. or higher and 150° C. or lower, the refractive index anisotropy of the liquid crystal component is 0.01 or more and 0.1 or less, The liquid crystal-polymer composite film can be switched between a transparent state and a colored state by application of a voltage.

2. 2. The liquid crystal device according to claim 1, wherein the liquid crystal composition has an average particle size of 2 [mu]m or more and 50 [mu]m or less.

3. 2. The liquid crystal device according to claim 1, wherein the average particle size of the liquid crystal composition is 0.01 [mu]m or more and less than 2 [mu]m.

4. 4. The liquid crystal device according to claim 1, wherein the dichroic dye contains an anthraquinone dye and / or an azo dye.

5. 5. The liquid crystal device according to claim 1, wherein the content of the dichroic dye relative to 100% by mass of the liquid crystal composition is 0.1% by mass or more and 20% by mass or less.

6. 6. The liquid crystal device according to claim 1, wherein the liquid crystal component is a nematic liquid crystal or a chiral nematic liquid crystal.

7. 7. The liquid crystal device according to claim 1, wherein the polymer constituting the polymer matrix contains at least one selected from the group consisting of polyurethane, polyacrylic, polyvinyl alcohol, and modified products thereof.

8. 8. The liquid crystal device according to claim 1, wherein the total light transmittance in the colored state is 0.1% or more and 30% or less.

9. 9. The liquid crystal device according to claim 1, wherein the total light transmittance in the transparent state is more than 30% and not more than 80%.

10. An emulsion composition in which a liquid crystal composition is dispersed in a medium containing water, the medium is a medium in which a polymer is dispersed or dissolved, the liquid crystal composition contains a liquid crystal component and a dichroic dye; the liquid crystal component has a positive dielectric anisotropy and an NI point of 110° C. or higher and 150° C. or lower; The emulsion composition, wherein the refractive index anisotropy of the liquid crystal component is 0.01 or more and 0.1 or less.

11. 11. The emulsion composition according to claim 10, wherein the average particle size of the liquid crystal composition in the emulsion composition is 2 μm or more and 50 μm or less.

12. 11. The emulsion composition according to claim 10, wherein the average particle size of the liquid crystal composition in the emulsion composition is 0.01 μm or more and less than 2 μm.

13. The emulsion composition according to any one of claims 10 to 12, wherein the dichroic dye contains an anthraquinone dye and / or an azo dye.

14. 14. The emulsion composition according to claim 10, wherein the content of the dichroic dye relative to 100% by mass of the liquid crystal composition is 0.1% by mass or more and 20% by mass or less.

15. The emulsion composition according to any one of claims 10 to 14, wherein the liquid crystal component is a nematic liquid crystal or a chiral nematic liquid crystal.

16. The emulsion composition according to any one of claims 10 to 15, wherein the polymer comprises at least one selected from the group consisting of polyurethane, polyacrylic, polyvinyl alcohol, and modified products thereof.

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