Temperature-responsive light control element and method of manufacturing the same

Abstract

To provide a temperature-responsive light control element which features a rectilinear transmittance of 80% or greater for light with wavelengths in a range of 400-2250 nm at 20°C, no polarization dependence of rectilinear transmittance and hemispherical transmittance at 20°C and 50°C, and reduced polarization dependence of a transmittance variation range at 20°C and 50°C, and to provide a method of manufacturing the same.SOLUTION: A temperature-responsive light control element (1) of the present invention comprises a liquid crystal layer (11) containing a low-molecular-weight liquid crystal, a high-molecular-weight liquid crystal, and a chiral agent, and a pair of base material layers (12, 13) sandwiching the liquid crystal layer, where the chiral agent content in the liquid crystal layer (11) is greater than 0 pts.mass and less than or equal to 1.1 pts.mass when the total amount of the low-molecular-weight liquid crystal and the high-molecular-weight liquid crystal is defined as 100 pts.mass.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a temperature-responsive light control element having a liquid crystal layer, a method for producing the same, and a liquid crystal layer-forming composition used to form the liquid crystal layer of the temperature-responsive light control element. [Background technology]

[0002] Conventionally, liquid crystal elements in which liquid crystal compounds are dispersed in a polymer matrix are capable of adjusting the light transmittance and scattering rate, and therefore, attempts have been made to apply them to display devices, optical shutters, light control panels, sensors, etc. Among these, liquid crystal elements in which the light transmittance changes with temperature have been actively developed, and the following technologies are known.

[0003] Patent Document 1 discloses an oriented phase separation structure of liquid crystal and polymer, characterized in that the liquid crystal material is phase-separated and dispersed as liquid crystal droplets in an anisotropic polymer, the phase of the liquid crystal material undergoes an optical anisotropy-isotropy change due to a nematic-isotropic phase transition, the anisotropic polymer phase has a solid phase structure in which the refractive index difference between the anisotropic polymer phase and the liquid crystal material phase in a nematic state matches for each independent polarized light component, and the structure can be reversibly changed to a light-scattering state at temperatures above the nematic-isotropic phase transition temperature and to a light-transmitting state at temperatures below the nematic-isotropic phase transition temperature, and a light-control window glass comprising the same.

[0004] Patent Document 2 discloses a temperature-responsive dimming element comprising a layer containing a liquid crystal compound and a polymer obtained by polymerizing a polymerizable liquid crystal compound having a cyanophenyl group, and a pair of substrates arranged on both sides of the layer.

[0005] Patent Document 3 discloses a liquid crystal display device comprising a layer containing a liquid crystal compound (A), a polymer of a polymerizable liquid crystal compound (B) having a cyanophenyl group, and a polymerizable compound (C) having two or more polymerizable groups, and a pair of substrates arranged on both sides of the layer, and wherein the phase transition temperature (T NI) is in the range of 20 to 120°C. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent Publication No. 2013-152445 [Patent Document 2] Patent Publication No. 2018-193456 [Patent Document 2] International Publication No. 2020 / 050224 Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention aims to provide a temperature-responsive photochromic element and a composite comprising the same, which are intended for application to photochromic elements such as photochromic windows that are transparent at room temperature (e.g., 20°C) and become translucent or opaque at 40°C or higher (e.g., 50°C). The element has a rectilinear transmittance of 80% or higher at 20°C for light with a wavelength of 400 to 2250 nm, no polarization dependence of the rectilinear transmittance and hemispherical transmittance at 20°C and 50°C, and reduced polarization dependence of the transmittance change range at these temperatures. Another objective of the present invention is to provide a method for efficiently producing such a temperature-responsive photochromic element and a liquid crystal layer-forming composition suitable for producing the liquid crystal layer that constitutes the element. In this specification, the phrase "reduced polarization dependence" is used to include the meaning of elimination of polarization dependence. [Means for solving the problem]

[0008] The inventors have discovered that in a temperature-responsive dimming element comprising a liquid crystal layer containing low-molecular-weight liquid crystal, high-molecular-weight liquid crystal, and a chiral material, and a pair of base layers arranged on both sides of the liquid crystal layer, when the content of the chiral material in the liquid crystal layer is set to a specific amount, the rectilinear transmittance at 20°C for light with a wavelength of 400 to 2250 nm is 80% or more, there is no polarization dependence of the rectilinear transmittance and hemispherical transmittance at 20°C and 50°C, and the polarization dependence of the transmittance change range at these temperatures is reduced.

[0009] The present invention is illustrated below. [1] A liquid crystal layer containing a low-molecular-weight liquid crystal, a high-molecular-weight liquid crystal, and a chiral material, and a pair of base layers disposed on both sides of the liquid crystal layer, A temperature-responsive dimming element in which the content of the chiral material contained in the liquid crystal layer is more than 0 parts by mass and not more than 1.1 parts by mass, when the total amount of the low molecular weight liquid crystal and the high molecular weight liquid crystal is 100 parts by mass. [2] The temperature-responsive light-controlling element according to [1] above, wherein the chiral material is an alicyclic compound containing an ester bond. [3] The temperature-responsive light-controlling element according to [1], wherein the low-molecular-weight liquid crystal contains a compound whose phase transition temperature from a nematic phase to an isotropic phase is in the range of 20°C to 120°C. [4] The temperature-responsive light-controlling element according to [1], wherein the polymer liquid crystal contains a structural unit derived from a monofunctional unsaturated compound having a cyanophenyl group. [5] The temperature-responsive light control element according to [1], wherein the substrate layer has an alignment film on the liquid crystal layer side. [6] A method for producing the temperature-responsive light-controlling element according to [1] above, a composition disposing step of disposing a liquid crystal layer forming composition between a pair of substrates, the composition including a low molecular weight liquid crystal, a monomer capable of being polymerized to form a polymer liquid crystal, a chiral material, and a polymerization initiator; a liquid crystal layer forming step of irradiating the liquid crystal layer forming composition with a laser or ultraviolet light to form a liquid crystal layer between the substrates, the liquid crystal layer containing the low molecular weight liquid crystal, the high molecular weight liquid crystal, and the chiral material; A method for manufacturing a temperature-responsive dimming element, comprising the steps of: [7] The method for producing a temperature-responsive light-controlling element according to [6] above, wherein the monomer comprises a monofunctional unsaturated compound having a cyanophenyl group. [8] A liquid crystal layer-forming composition used in the method for producing a temperature-responsive light-controlling element according to [6] above, A liquid crystal layer-forming composition containing a low-molecular-weight liquid crystal, a monomer that polymerizes to form a polymeric liquid crystal, a chiral material, and a polymerization initiator. [9] A composite comprising the temperature-responsive light-controlling element according to [1] above. [Effects of the Invention]

[0010] According to the temperature-responsive light control element of the present invention, the content of the chiral agent in the liquid crystal layer is set to a specific amount, so that the rectilinear transmittance of light with a wavelength of 400 to 2250 nm at 20° C. is 80% or more, the rectilinear transmittance and hemispherical transmittance are not dependent on polarization at 20° C. and 50° C., and the polarization dependence of the transmittance change range at these temperatures is reduced. Therefore, the temperature-responsive light control element of the present invention can be used in combination with, for example, a frame, a protective film, etc. to form the composite of the present invention, which can be suitably used as a light control element for a light control window or the like. The composition for forming a liquid crystal layer of the present invention is suitable for producing the above-mentioned temperature-responsive light control element. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic cross-sectional view showing an example of a temperature-responsive light-controlling element of the present invention. [Figure 2] FIG. 2 is a schematic diagram illustrating a method for measuring the rectilinear transmittance of a temperature-responsive light-control element. [Figure 3] FIG. 1 is a schematic explanatory diagram showing a method for measuring the hemispherical transmittance of a temperature-responsive light-control element. [Figure 4] 1 is a graph showing the wavelength distribution of human visual sensitivity and AM1.5 solar radiation intensity on the ground. [Figure 5] 1 is a graph showing the rectilinear transmittance of the temperature-responsive light control element (EE1) obtained in Comparative Example 1. [Figure 6] 1 is a graph showing the hemispherical transmittance of the temperature-responsive light control element (EE1) obtained in Comparative Example 1. [Figure 7] 10 is a graph showing the rectilinear transmittance of the temperature-responsive light control element (EE2) obtained in Comparative Example 2. [Figure 8] 10 is a graph showing the hemispherical transmittance of the temperature-responsive light control element (EE2) obtained in Comparative Example 2. [Figure 9] 1 is a graph showing the rectilinear transmittance of the temperature-responsive light control element (E3) obtained in Example 3. [Figure 10] 1 is a graph showing the hemispherical transmittance of the temperature-responsive light-control element (E3) obtained in Example 3. [Figure 11] 1 is a graph showing the relationship between the concentration of a chiral material in the liquid crystal layer and the rectilinear transmittance of visible light in the temperature-responsive light control elements obtained in Examples 1 to 4 and Comparative Examples 1 and 2. [Figure 12] 1 is a graph showing the relationship between the concentration of a chiral material in the liquid crystal layer of the temperature-responsive light control elements obtained in Examples 1 to 4 and Comparative Examples 1 and 2 and the hemispherical transmittance of solar radiation. [Figure 13] 13 is a graph showing the chiral material concentration dependency of the change width (ΔTlum, ΔTsol) of the rectilinear transmittance of visible light and the hemispherical transmittance of solar radiation with temperature change, created based on FIGS. 11 and 12. FIG. [Figure 14] 10 is a graph showing the dependency of the polarization degree of the rectilinear transmittance on the concentration of the chiral material. [Figure 15] 10 is a graph showing the dependency of the polarization degree of hemispherical transmittance on the concentration of a chiral material. [Figure 16] 1 shows an external image of the temperature-responsive light-control element (E3) obtained in Example 3, which was illuminated from behind and photographed with an optical microscope under crossed Nicols configuration. [Figure 17] 1 shows an external image of the temperature-responsive light-control element (EE1) obtained in Comparative Example 1, which was illuminated from behind and photographed with an optical microscope under crossed Nicols arrangement. [Figure 18] 1 shows an external image of the temperature-responsive light-control element (EE2) obtained in Comparative Example 2, which was illuminated from behind and photographed with an optical microscope under crossed Nicols arrangement. [Figure 19]The images of the temperature-responsive dimming element (EE2) obtained in Comparative Example 2 were taken with a polarizing microscope. (a) is an image taken at a temperature of 20°C and under conditions of a crossed Nicol arrangement with two polarizers oriented at 45° and −45°, respectively. (b) is an image taken at a temperature of 50°C and under conditions of a crossed Nicol arrangement with two polarizers oriented at 45° and −45°, respectively. (c) is an image taken at a temperature of 20°C and under conditions of a crossed Nicol arrangement with two polarizers oriented at 0° and 90°, respectively. (d) is an image taken at a temperature of 50°C and under conditions of a crossed Nicol arrangement with two polarizers oriented at 0° and 90°, respectively. [Figure 20] The images of the temperature-responsive dimming element (E3) obtained in Example 3 were taken with a polarizing microscope. (a) is an image taken at a temperature of 20°C, 45°, and under crossed Nicol arrangement conditions with two polarizers oriented at 45° and −45°, respectively; (b) is an image taken at a temperature of 50°C, 45°, and under crossed Nicol arrangement conditions with two polarizers oriented at 45° and −45°, respectively; (c) is an image taken at a temperature of 20°C, and under crossed Nicol arrangement conditions with two polarizers oriented at 0° and 90°, respectively; and (d) is an image taken at a temperature of 50°C, and under crossed Nicol arrangement conditions with two polarizers oriented at 0° and 90°, respectively. [Figure 21] The images of the temperature-responsive dimming element (EE1) obtained in Comparative Example 1 were taken with a polarizing microscope. (a) is an image taken at a temperature of 20°C and under conditions of a crossed Nicol arrangement with two polarizers oriented at 45° and −45°, respectively. (b) is an image taken at a temperature of 50°C and under conditions of a crossed Nicol arrangement with two polarizers oriented at 45° and −45°, respectively. (c) is an image taken at a temperature of 20°C and under conditions of a crossed Nicol arrangement with two polarizers oriented at 0° and 90°, respectively. (d) is an image taken at a temperature of 50°C and under conditions of a crossed Nicol arrangement with two polarizers oriented at 0° and 90°, respectively. (e) and (f) are low-magnification images of (a) and (b), respectively. DETAILED DESCRIPTION OF THE INVENTION

[0012] The temperature-responsive dimming element of the present invention is, for example, a temperature-responsive dimming element 1 having a structure shown in FIG. 1 and comprising a liquid crystal layer 11 containing low-molecular-weight liquid crystal, high-molecular-weight liquid crystal, and a chiral material, and a pair of base layers 12 and 13 arranged on both sides of the liquid crystal layer 11, and is characterized in that the content of the chiral material in the liquid crystal layer 11 is more than 0 parts by mass and not more than 1.1 parts by mass, when the total amount of the low-molecular-weight liquid crystal and the high-molecular-weight liquid crystal is 100 parts by mass.

[0013] First, the liquid crystal layer 11 containing low molecular weight liquid crystal, high molecular weight liquid crystal and chiral material will be described.

[0014] The low molecular weight liquid crystal contained in the liquid crystal layer 11 is a liquid crystal compound that does not contain repeating units derived from a monomer, and is preferably a liquid crystal compound that exhibits an optical anisotropy-isotropy change due to a liquid crystal phase-isotropic phase transition, and more preferably a liquid crystal compound whose liquid crystal phase is a nematic phase (hereinafter also referred to as a "nematic liquid crystal compound").

[0015] Although the nematic liquid crystal compound is not particularly limited, if the phase transition temperature from the nematic phase to the isotropic phase is preferably in the range of 20° C. to 120° C., more preferably 25° C. to 100° C., even more preferably 30° C. to 80° C., and particularly preferably 30° C. to 50° C., when used as a temperature-responsive light-controlling element in a window member or the like, it is possible to efficiently form a liquid crystal layer that has high transmittance under conditions where it is preferred to let sunlight into the room, such as winter, and has a high light-blocking ratio under conditions where it is preferred to block sunlight, such as summer. In the present invention, the "phase transition temperature from the nematic phase to the isotropic phase" includes both the phase transition temperature from the nematic phase to the isotropic phase and the phase transition temperature from the isotropic phase to the nematic phase. The phase transition temperature can be measured using a polarizing microscope equipped with a temperature control stage, a differential scanning calorimeter, or the like.

[0016] Examples of nematic liquid crystal compounds include compounds having a cyanobiphenyl structure, compounds having a cyanoterphenyl structure, compounds having a cyanophenyl ester structure, etc. These compounds may be contained in the liquid crystal layer 11 either alone or in combination of two or more.

[0017] The nematic liquid crystal compound according to the present invention preferably contains a compound having a cyanobiphenyl structure (hereinafter referred to as a "cyanobiphenyl-based liquid crystal compound"). Examples of the cyanobiphenyl-based liquid crystal compound include a 4-cyano-4'-alkylbiphenyl compound represented by the following general formula (1) and a 4-cyano-4'-alkoxybiphenyl compound represented by the following general formula (2). [ka] (In the formula, R 1 is a hydrocarbon group.) [ka] (In the formula, R 2 is a hydrocarbon group.)

[0018] In the above general formula (1), R 1 is preferably an alkyl group, and particularly preferably an alkyl group having 1 to 9 carbon atoms.

[0019] In the above general formula (2), R 2 is preferably an alkyl group, and particularly preferably an alkyl group having 1 to 9 carbon atoms.

[0020] The cyanobiphenyl liquid crystal compound is preferably a 4-cyano-4'-alkylbiphenyl compound represented by the above general formula (1), such as 4-cyano-4'-pentylbiphenyl, 4-cyano-4'-hexylbiphenyl, 4-cyano-4'-heptylbiphenyl, etc.

[0021] The liquid crystal layer 11 may contain only one type of low molecular weight liquid crystal or two or more types of low molecular weight liquid crystal.

[0022] The polymer liquid crystal contained in the liquid crystal layer 11 is a polymer liquid crystal compound containing repeating units derived from a monomer, and preferably contains repeating units derived from a monofunctional unsaturated compound having a cyanophenyl group (hereinafter referred to as "liquid crystal monomer (M1)") in an amount of preferably 95% by mass or more, more preferably 96% by mass or more. The polymer liquid crystal according to the present invention is particularly preferably a polymer liquid crystal compound having a crosslinked structure (hereinafter referred to as "a polymer liquid crystal compound containing a cyanophenyl structure").

[0023] The cyanophenyl group contained in the liquid crystal monomer (M1) may be contained as a cyanophenyl ester group, a cyanobiphenyl group, or the like.

[0024] Examples of the liquid crystal monomer (M1) include a monomer (m1) represented by the following general formula (3) and a monomer (m2) represented by the following general formula (4). [ka] (In the formula, R 3 is an organic group containing a polymerizable group, and R 4 is an alkylene group or an oxyalkylene group, and n is an integer. [ka] (In the formula, R 5 is an organic group containing a polymerizable group, and R 6 is an alkylene group or an oxyalkylene group, and n is an integer.

[0025] In the above general formula (3), R 3 is preferably an organic group containing a photopolymerizable group, and can be an organic group containing an acryloyl group, a methacryloyl group, an epoxy bond, a vinyl group, etc. Among these, an organic group containing an acryloyl group or a methacryloyl group is preferred.

[0026] In the above general formula (3), R 4is preferably an alkylene group or oxyalkylene group having 1 to 12 carbon atoms, and particularly preferably a linear alkylene group. Furthermore, n is preferably 1 to 12, but -[R 4 O] n -R in 4 The number of carbon atoms is 1 to 12.

[0027] Examples of the monomer (m1) represented by the above general formula (3) include 4-[(6-acryloyloxy)hexyloxy]-4'-cyanobiphenyl, 3-(4'-cyanobiphenyl-4-yloxy)propyl acrylate, and the like.

[0028] In the above general formula (4), R 5 is preferably an organic group containing a photopolymerizable group, and can be an organic group containing an acryloyl group, a methacryloyl group, an epoxy bond, a vinyl group, etc. Among these, an organic group containing an acryloyl group or a methacryloyl group is preferred.

[0029] In the above general formula (4), R 6 is preferably an alkylene group or oxyalkylene group having 1 to 12 carbon atoms, and particularly preferably a linear alkylene group. Furthermore, n is preferably 1 to 12, but -[R 6 O] n -R in 6 The number of carbon atoms is 1 to 12.

[0030] Examples of the monomer (m2) represented by the above general formula (4) include 4-cyanophenyl 4-(6-acryloyloxyhexyloxy)benzoate.

[0031] The crosslinked structure contained in the cyanophenyl structure-containing polymeric liquid crystal compound is preferably derived from a polyfunctional monomer having two or more polymerizable groups. The polymerizable group is preferably a photopolymerizable group, and can be an organic group including an acryloyl group, a methacryloyl group, an epoxy group, a vinyl group, a vinyloxy group, or the like. Among these, a (meth)acryloyl group, an epoxy group, and a vinyl group are preferred, and a (meth)acryloyl group is particularly preferred. In the above description, the term "(meth)acryloyl group" means an acryloyl group or a methacryloyl group.

[0032] The number of polymerizable groups contained in the polyfunctional monomer is preferably 2 to 5, more preferably 2 to 3, and particularly preferably 2.

[0033] Examples of the polyfunctional monomer include aliphatic polyfunctional (meth)acrylates such as linear or branched alkylene glycol di(meth)acrylate, alkylene glycol tri(meth)acrylate, alkylene glycol tetra(meth)acrylate, alkylene glycol penta(meth)acrylate, and alkylene glycol hexa(meth)acrylate; and di(meth)acrylates or tri(meth)acrylates having a cyclic structure such as an alicyclic, aromatic, or heterocyclic structure. Among these, examples of aliphatic polyfunctional (meth)acrylates include 1,6-hexanediol di(meth)acrylate, ethylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, dipentaerythritol pentaacrylate, etc. Examples of cyclic structure-containing di(meth)acrylates include tricyclodecane dimethanol di(meth)acrylate, bisphenol A di(meth)acrylate, bisphenol F di(meth)acrylate, etc. In the above description, "(meth)acrylate" means acrylate or methacrylate.

[0034] The average molecular weight of the cyanophenyl structure-containing polymeric liquid crystal compound is preferably 3500 or more, more preferably 7000 or more, from the viewpoint of viscosity reduction and structural stability at high temperatures, for example, 50° C. or more (usually 80° C. or less). The upper limit is usually 8000.

[0035] The chiral agent contained in the liquid crystal layer 11 is not particularly limited as long as it is a compound that imparts optical rotation to the molecular orientation, and any conventionally known compound can be used. As the chiral agent according to the present invention, an alicyclic compound containing an ester bond is preferred, and the following compounds are particularly preferred. [ka] [ka]

[0036] The content of the chiral material contained in the liquid crystal layer 11 is more than 0 parts by mass and not more than 1.1 parts by mass, preferably 0.12 to 0.8 parts by mass, when the total amount of the low molecular weight liquid crystal and the high molecular weight liquid crystal is 100 parts by mass, since the rectilinear transmittance at 20°C for light with wavelengths of 500 to 2250 nm is 80% or more and the polarization dependence of the rectilinear transmittance and hemispherical transmittance at 20°C and 50°C can be reduced.

[0037] The liquid crystal layer 11 is typically a layer containing a matrix of polymer liquid crystals, in which low-molecular-weight liquid crystals and a chiral agent are dispersed. In the temperature-responsive light control element of the present invention, the liquid crystal layer 11 may contain, as necessary, an antioxidant, an ultraviolet absorber, a light stabilizer, a leveling agent, a colorant, a sensitizer, a filler, and the like.

[0038] The molecules of the low-molecular-weight liquid crystal contained in the liquid crystal layer 11 are oriented such that their major axes extend in the same direction as the orientation direction of the polymeric liquid crystal at temperatures below the phase transition temperature from the nematic phase to the isotropic phase. On the other hand, at temperatures above the phase transition temperature from the nematic phase to the isotropic phase, the low-molecular-weight liquid crystals align such that their major axes extend in a direction different from the orientation direction of the polymeric liquid crystals. Therefore, the liquid crystal layer 11 reversibly changes from a light-transmitting state at temperatures below the phase transition temperature from the nematic phase to the isotropic phase of the low-molecular-weight liquid crystal to a light-scattering state at temperatures above the phase transition temperature from the nematic phase to the isotropic phase. Furthermore, in the temperature-responsive light control device of the present invention, the liquid crystal layer 11 contains a specific proportion of chiral material, so that the uniformly oriented low-molecular-weight liquid crystals are confined to minute domains, resulting in a multi-domain structure in which individual domains in which the low-molecular-weight liquid crystals are oriented in various directions are distributed. For example, the liquid crystal layer 11 is transparent at a temperature of 20°C and translucent or opaque at 50°C.

[0039] From the above viewpoints, the content of the low molecular weight liquid crystal in the liquid crystal layer 11 is preferably 200 to 300 parts by mass, more preferably 220 to 280 parts by mass, and even more preferably 240 to 260 parts by mass, based on 100 parts by mass of the polymer liquid crystal. In addition, the content of the chiral agent in the liquid crystal layer 11 is preferably 0.4 to 3.9 parts by mass, more preferably 1.0 to 3.0 parts by mass, and even more preferably 1.6 to 1.9 parts by mass, based on 100 parts by mass of the polymer liquid crystal.

[0040] The thickness of the liquid crystal layer 11 is not particularly limited, but is preferably 5 to 300 μm, and more preferably 30 to 50 μm.

[0041] Next, the base layers 12 and 13 will be described.

[0042] The substrate layers 12 and 13 are preferably transparent layers, regardless of whether they are colored or not. In the present invention, thin transparent layers made primarily of resin films (such as polyester resin films, polyolefin resin films, polyamide resin films, polycarbonate resin films, polyarylate resin films, polystyrene resin films, acrylic resin films, cellulose derivative films, polyethersulfone resin films, polyimide resin films, polyphenylene sulfide resin films, and polyphenylene ether resin films), glass plates, and the like are particularly preferred. The substrate layers 12 and 13 may be either single-layer or multi-layer types, but are preferably multi-layer types having an alignment film on the liquid crystal layer 11 side that facilitates alignment of the polymer liquid crystal and the low-molecular-weight liquid crystal. In particular, multi-layer types having an alignment film that facilitates alignment of the polymer liquid crystal and the low-molecular-weight liquid crystal parallel to the substrate layer surface are more preferred.

[0043] The alignment film may be a film containing at least one selected from polyimide and its hydrolyzates such as polyamic acid, polyacrylamide, polyamide, polyethyleneimine, polysiloxane, polyvinyl alcohol, polyoxazole, polyvinylpyrrolidone, polyacrylic acid, polystyrene, polyphenylene ether, polyarylate, polyethylene terephthalate, polyethersulfone, epoxy resin, epoxy acrylate resin, etc. Of these, polyimide is preferred.

[0044] When the base layers 12 and 13 have an alignment film on the liquid crystal layer 11 side, the low-molecular-weight liquid crystal contained in the liquid crystal layer 11 can maintain high alignment order in a specific direction in the nematic phase at a temperature below the phase transition temperature from the nematic phase to the isotropic phase, thereby achieving high light transmittance. The thickness of the alignment film is not particularly limited.

[0045] There are no particular limitations on the thickness of each of the base layers 12 and 13, but it is preferably 10 to 5000 μm, more preferably 700 to 1100 μm.

[0046] The temperature-responsive light control element of the present invention is preferably an integrated product of the liquid crystal layer 11 and the base layers 11 and 12 sandwiching the liquid crystal layer 11 .

[0047] The temperature-responsive light control element of the present invention may be used alone, but can also be used as a composite (composite of the present invention) further comprising an adhesive layer, a protective film, a frame, etc.

[0048] For example, if the base layers 12 and 13 are made of a resin film, and the temperature-responsive light-control element is substantially made of a resin material, forming a transparent adhesive layer on one of the base layers makes it possible to obtain a composite that can be easily attached to window glass, etc. The transparent adhesive layer can preferably be derived from an adhesive film or an adhesive film having adhesive layers on both sides.

[0049] The temperature-responsive light-controlling element of the present invention has a linear transmittance of visible light (T lum ) is preferably more than 76.9%, more preferably 80% or more, particularly preferably 83.1% or more at 20°C, and is preferably less than 2.8%, more preferably 1% or less, particularly preferably 0.6% or less at 50°C. Therefore, in the temperature responsive light control element of the present invention, the difference between the rectilinear transmittance at 20° C. and the rectilinear transmittance at 50° C. is preferably more than 74.1%, more preferably 80% or more, and particularly preferably 82.4% or more.

[0050] Furthermore, the hemispherical transmittance (T sol ) is preferably 88.7% or more, more preferably 89% or more, and particularly preferably 89.1% or more at 20°C, and is preferably less than 68.8%, more preferably 68% or less, and particularly preferably 67.3% or less at 50°C. Therefore, in the temperature responsive light control element of the present invention, the difference between the hemispherical transmittance at 20° C. and the hemispherical transmittance at 50° C. is preferably more than 20.3%, more preferably 21% or more, and particularly preferably 21.6% or more.

[0051] The rectilinear transmittance is usually the transmittance when light (incident light) is incident on the temperature-responsive photochromic element 1 in a vertical direction (incident angle: 0°) and only the rectilinear transmitted light (detection angle: 0°) is detected from the temperature-responsive photochromic element 1. However, in the present invention, the rectilinear transmittance (T lum ) is the transmittance measured within a divergence angle of 10° using an opening in front of integrating sphere detector 20, which is placed away from the transmission side of temperature-responsive photochromic element 1 after light is incident thereon, as shown in FIG. 2.

[0052] The rectilinear transmittance changes depending on whether the liquid crystal layer 11 of the temperature-responsive light switchable element 1 is in a transparent state or a cloudy state. In the cloudy state, the light incident on the temperature-responsive light switchable element 1 is scattered in all directions. Therefore, in the present invention, the hemispherical transmittance (T sol ) is the transmittance of the total transmitted light, which is the sum of scattered light and straight light, and is the transmittance measured by placing an integrating sphere detector 20 in close contact with the transmission side surface of the temperature-responsive photochromic element 1, as shown in FIG.

[0053] The rectilinear transmittance and hemispherical transmittance were measured in two directions, P polarized light (polarized light parallel to the rubbing direction of the liquid crystal layer 11) and S polarized light (polarized light perpendicular to the rubbing direction of the liquid crystal layer 11). The rectilinear transmittance for P polarized light and S polarized light were respectively expressed as T d,P and T d,S Similarly, the hemispherical transmittance is T h,P and T h,S Then, the linear transmittance T d and hemispherical transmittance T h is expressed by the following formulas (F1) and (F2), and is estimated by the average value of the transmittance of P-polarized light and S-polarized light. T d =(T d,P +T d,S ) / 2 (F1) T h =(T h,P +T h,S ) / 2 (F2)

[0054] Therefore, the rectilinear transmittance (T lum ) and the hemispherical transmittance of solar radiation (T sol) is a function of wavelength T d and T h From this, it was calculated using the following formulas (F3) and (F4).

number

[0055] Here, the rectilinear transmittance is calculated by the human visual sensitivity function φ at each wavelength as described in JIS R 3106, as shown in FIG. lum The hemispherical transmittance is the wavelength distribution φ of the solar radiation intensity on the ground of AM1.5 as described in JIS R 3106. sol It is a weighted average by (λ).

[0056] The polarization degree γ of the rectilinear transmittance of light having a wavelength of 400 to 2250 nm at 20°C and 50°C of the temperature-responsive light control element of the present invention d and the degree of polarization of the hemispherical transmittance γ h is the above T d,P , T d,S , T h,P and T h,S Using these, it can be calculated using the following formulas (F5) and (F6). gamma d =(T d,S -T d,P ) / (T d,S +T d,P ) (F5) gamma h =(T h,S -T h,P ) / (T h,S +T h,P ) (F6) In the present invention, the polarization dependency of the transmittance change width is reduced, so that, for example, the degree of polarization γ d is preferably 0.05 or less, more preferably 0.02 or less, and the degree of polarization at 50° C. γ d is preferably 0.80 or less, more preferably 0.72 or less, and the degree of polarization at 20°C γ h is preferably 0.02 or less, and the degree of polarization at 50°C γ his preferably 0.02 or less. Even if the content of the chiral material in the liquid crystal layer 11 exceeds 1.1 parts by mass, the polarization dependency of the transmittance change range may be reduced, but high rectilinear transmittance at 20°C cannot be obtained, making the liquid crystal layer unsuitable for light control windows, temperature sensors, optical shutters, etc.

[0057] The method for producing a temperature-responsive dimming element of the present invention sequentially comprises a composition disposing step of disposing a liquid crystal layer-forming composition containing a low molecular weight liquid crystal, a monomer that polymerizes to produce a polymer liquid crystal, a chiral material, and a polymerization initiator between a pair of substrates, and a liquid crystal layer forming step of irradiating the liquid crystal layer-forming composition with a laser or ultraviolet light to form a liquid crystal layer containing the low molecular weight liquid crystal, the polymer liquid crystal, and the chiral material between the substrates.

[0058] In the composition disposing step, a liquid crystal layer forming composition (the liquid crystal layer forming composition of the present invention) containing low molecular weight liquid crystal, a monomer that is polymerized to form a polymer liquid crystal, a chiral agent, and a polymerization initiator is used. The low molecular weight liquid crystal and the chiral agent are as described above.

[0059] The monomer to be polymerized to form the polymer liquid crystal preferably contains the above-mentioned liquid crystal monomer (M1). Furthermore, other monomers polymerizable with the liquid crystal monomer (M1) can be used as long as they do not impair the optical anisotropy. The other monomers are not particularly limited and may be either monofunctional or polyfunctional monomers. In the present invention, when other monomers are used, it is preferable to use the above-mentioned polyfunctional monomers. When the liquid crystal monomer (M1) and the polyfunctional monomer are used in combination, the proportion of the liquid crystal monomer (M1) used is preferably 95 to 99% by mass, more preferably 96 to 98% by mass, based on the total of both.

[0060] The polymerization initiator contained in the liquid crystal layer-forming composition is preferably a photoradical polymerization initiator. The photoradical polymerization initiator is not particularly limited as long as it generates radicals or acids upon irradiation with ultraviolet light or visible light and initiates a chain polymerization reaction, and conventionally known compounds can be used.

[0061] Examples of photoradical polymerization initiators include benzoins such as benzoin, benzoin methyl ether, and benzoin propyl ether; acetophenones such as acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 1,1-dichloroacetophenone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-propan-1-one, and N,N-dimethylaminoacetophenone; anthraquinones such as 2-methylanthraquinone, 1-chloroanthraquinone, and 2-amylanthraquinone; Examples of suitable thioxanthones include 4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2-chlorothioxanthone, and 2,4-diisopropylthioxanthone; ketals such as acetophenone dimethyl ketal and benzyl methyl ketal; benzophenones such as benzophenone, methylbenzophenone, 4,4'-dichlorobenzophenone, 4,4'-bisdiethylaminobenzophenone, Michler's ketone, and 4-benzoyl-4'-methyldiphenyl sulfide; and 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,4,4'-trimethylpentylphosphine oxide and camphorquinone.

[0062] The content of the polymerization initiator in the liquid crystal layer-forming composition is preferably 2.0 to 5.0 mass %, more preferably 3.0 to 3.2 mass %, based on the total amount of monomers that are polymerized to form polymeric liquid crystals.

[0063] The liquid crystal layer forming composition may further contain an antioxidant, an ultraviolet absorber, a light stabilizer, a leveling agent, a colorant, a sensitizer, a filler, and the like.

[0064] The composition for forming a liquid crystal layer is preferably a liquid composition in which the low molecular weight liquid crystal contains a nematic liquid crystal compound, the monomer to be polymerized to form a polymer liquid crystal contains a liquid crystal monomer (M1), i.e., a monofunctional unsaturated compound having a cyanophenyl group, and the chiral agent is contained in an amount of more than 0 parts by mass and not more than 1.1 parts by mass, when the total amount of the monomer to form the polymer liquid crystal and the low molecular weight liquid crystal is taken as 100 parts by mass. More preferably, the low molecular weight liquid crystal contains a compound having a phase transition temperature from a nematic phase to an isotropic phase in the range of 20°C to 120°C, and the monomer to be polymerized to form a polymer liquid crystal contains, as the liquid crystal monomer (M1), a compound represented by the above general formula (3) or (4) and two or more polymerizable groups. The chiral agent is contained in a liquid composition in an amount of more than 0 parts by weight to 1.1 parts by weight or less, based on 100 parts by weight of the combined total of the monomers for forming the polymer liquid crystal and the low molecular weight liquid crystal. Particularly preferred is a liquid composition in which the low molecular weight liquid crystal contains a compound represented by general formula (1) or (2), the monomers for polymerizing to form the polymer liquid crystal contain a compound represented by general formula (3) or (4) as the liquid crystal monomer (M1) and a polyfunctional monomer having two or more (meth)acryloyl groups, and the chiral agent is contained in an amount of more than 0 parts by weight to 1.1 parts by weight or less, based on 100 parts by weight of the combined total of the monomers for forming the polymer liquid crystal and the low molecular weight liquid crystal. The chiral agent content is preferably 0.12 to 0.8 parts by weight.

[0065] The liquid crystal layer forming composition may contain an organic solvent, if necessary.

[0066] The liquid crystal layer-forming composition can be prepared by mixing raw material components under light-shielding conditions.

[0067] The composition disposing step is a step of disposing a liquid crystal layer forming composition between a pair of substrates, and specifically, the following method can be applied. (P1) A method of injecting a liquid crystal layer forming composition between substrates having a gap at a predetermined interval. (P2) A method in which a liquid crystal layer-forming composition is applied to the surface of one substrate, and the coated surface of the substrate with the coating film is bonded to another substrate. (P3) A method in which a liquid crystal layer-forming composition is applied to the surfaces of two substrates, and the coated surfaces of the two substrates with coating films are bonded together.

[0068] The substrate is a thin, transparent body mainly made of a resin film, a glass plate, or the like, and it is preferable that the surface of the substrate that comes into contact with the liquid crystal layer-forming composition has an alignment film that makes it easier to align the high molecular weight liquid crystal and low molecular weight liquid crystal synthesized in the subsequent liquid crystal layer-forming process.

[0069] The alignment film may be made of polyimide or the like, and the substrate with the alignment film can be obtained, for example, by applying a solution containing polyimide to the substrate and then subjecting the resulting coating film to an alignment treatment such as rubbing, stretching, irradiation with polarized ultraviolet and visible light, ion beam irradiation, etc. The alignment direction may be parallel to the coating film on the substrate surface in a specific direction, or may be perpendicular to the coating film.

[0070] In the case of the above method (P1), the distance between the substrates is preferably 10 to 300 μm, more preferably 30 to 50 μm. When the liquid crystal layer forming composition is poured into a gap of a predetermined distance, the liquid crystal layer forming composition may be heated in advance so that the composition is in a sufficiently fluid state. In the above methods (P2) and (P3), the liquid crystal layer forming composition to be applied to the surface of the substrate may be heated in advance.

[0071] In the liquid crystal layer forming step, the liquid crystal layer forming composition between the substrates is irradiated with a laser or ultraviolet light.

[0072] The laser may be any of a solid-state laser, a gas laser, and a liquid laser. Specifically, a semiconductor pumped laser (such as a YAG laser), an excimer laser, an argon laser, etc. can be used. The wavelength of the irradiated laser is not particularly limited as long as it is within the reaction range of the photopolymerization initiator. The laser irradiation time is appropriately set depending on the type of laser, the composition of the liquid crystal layer-forming composition, etc., and is not particularly limited.

[0073] The ultraviolet light can be irradiated using a device that uses a light source such as an ultraviolet LED, a metal halide lamp, a high-pressure mercury lamp, or an ultra-high-pressure mercury lamp. The wavelength of the irradiated ultraviolet light is not particularly limited as long as it is within the reaction range of the photopolymerization initiator. The intensity of the ultraviolet light is preferably 0.06 to 192 mW / cm. 2 , more preferably 1 to 50 mW / cm 2 The energy amount of the ultraviolet light is appropriately set depending on the composition of the liquid crystal layer-forming composition, etc., but is preferably 100 to 1200 mJ / cm. 2 , more preferably 300 to 600 mJ / cm 2 The irradiation time of the ultraviolet rays is set appropriately depending on the intensity of the ultraviolet rays to be irradiated.

[0074] In the liquid crystal layer forming step, laser irradiation and ultraviolet irradiation may be used in combination. For example, ultraviolet irradiation may be performed after laser irradiation.

[0075] When laser irradiation or ultraviolet irradiation is performed, the pair of substrates containing the liquid crystal layer forming composition may be heated. The laser irradiation or ultraviolet irradiation may be either non-uniform exposure using a light diffusion plate or uniform exposure without using a light diffusion plate.

[0076] In the liquid crystal layer forming process, the monomers contained in the liquid crystal layer forming composition are polymerized to form polymer liquid crystals, and a liquid crystal layer can be obtained in which low molecular weight liquid crystals and chiral materials are dispersed in a matrix made of polymer liquid crystals. [Example]

[0077] The present invention will be explained in more detail below by way of examples, but the present invention is not limited to these examples.

[0078] 1. Manufacturing materials for temperature-responsive dimming elements The raw materials for manufacturing the liquid crystal layer and the substrate layer are shown below.

[0079] 1-1. Liquid crystal layer manufacturing materials (1) Low-molecular-weight liquid crystal 4-cyano-4'-heptylbiphenyl manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. was used. The phase transition temperature from the nematic phase to the isotropic phase is 42°C. (2) Monomer 1 4-[(6-acryloyloxy)hexyloxy]-4'-cyanobiphenyl manufactured by Tokyo Chemical Industry Co., Ltd. was used. (3) Monomer 2 1,6-hexanediol diacrylate manufactured by Tokyo Chemical Industry Co., Ltd. was used. (4) Polymerization initiator 2,2-Dimethoxy-2-phenylacetophenone manufactured by Tokyo Chemical Industry Co., Ltd. was used. (5) Chiral materials The product used was "NYC-2132L" (trade name) manufactured by LCC and represented by the following structural formula. [ka]

[0080] 1-2. Raw materials for manufacturing the base layer The glass substrate used was a 25mm x 20mm x 0.7mm glass substrate with a polyimide alignment film, manufactured by EHC Corp., which had been oriented by rubbing the glass surface with a polyimide film in one direction with a velvet cloth.

[0081] 2. Fabrication and evaluation of temperature-responsive dimming devices Example 1 70.8% by mass of low molecular weight liquid crystal, 28.4% by mass of monomer 1, 0.8% by mass of monomer 2, and 0.9 parts by mass of polymerization initiator and 0.12 parts by mass of chiral agent were mixed with a total of 100 parts by mass of these to obtain a liquid raw material mixture. Next, this raw material mixture was stirred for 2 hours while maintaining the temperature at 60°C in the dark to obtain a transparent mixed liquid. Thereafter, this mixed liquid was supplied between two glass substrates with polyimide alignment films, arranged with a gap of 50 μm so that the polyimide alignment films faced each other, to prepare a sample cell. Then, this sample cell was placed on a temperature-controlled plate at 20°C, and 1 mW / cm was applied to the mixed liquid in the sample cell. 2The temperature-responsive light-control element (hereinafter also referred to as "element (E1)") was obtained (see Table 1).

[0082] Examples 2 to 4 Except for using the raw materials shown in Table 1 to form the liquid crystal layer, the same operations as in Example 1 were performed to obtain temperature-responsive dimming elements (hereinafter also referred to as "element (E2)," "element (E3)," and "element (E4)," respectively) (see Table 1).

[0083] Comparative Examples 1-2 Except for using the raw materials shown in Table 1 to form the liquid crystal layer, the same operations as in Example 1 were performed to obtain temperature-responsive dimming elements (hereinafter also referred to as "Element (EE1)" and "Element (EE2)") (see Table 1).

[0084] [Table 1]

[0085] Next, various measurements were carried out on the obtained elements (E3), (EE1) and (EE2).

[0086] [1] Transmittance (rectilinear transmittance and hemispherical transmittance) The thickness-direction transmittance (linear transmittance and hemispherical transmittance) of the temperature-responsive switchable element was measured at 20°C (hereinafter referred to as "low temperature") and 50°C (hereinafter referred to as "high temperature") with different polarization directions (P-polarized and S-polarized) using a Hitachi High-Tech Solutions spectrophotometer "U4100" (model name) in the wavelength range of 250 to 2500 nm. Here, the polarization direction of P-polarized light is parallel to the rubbing alignment treatment, and the polarization direction of S-polarized light is perpendicular to the rubbing alignment treatment. The linear transmittance was measured within a divergence angle of 10° using an integrating sphere detector placed away from the transmission side of the temperature-responsive switchable element, as shown in Figure 2. The hemispherical transmittance was measured using an integrating sphere detector placed in close contact with the transmission side of the temperature-responsive switchable element, as shown in Figure 3. It was the transmittance of the total transmitted light, including both scattered and linear light, measured using an integrating sphere detector placed in close contact with the transmission side of the temperature-responsive switchable element. Furthermore, from the measured rectilinear transmittance and hemispherical transmittance, the rectilinear transmittance T of unpolarized light can be calculated using the above formulas (F1) and (F2). d and hemispherical transmittance T h was calculated, and each transmittance is reflected in Figs.

[0087] Figures 7 and 8 show spectroscopic data for the rectilinear transmittance and hemispherical transmittance of an element (EE2) that does not contain a chiral material. Figure 7 shows that there is a wide wavelength range where the rectilinear transmittance of P-polarized light and S-polarized light do not match, at both low and high temperatures, indicating polarization dependency. Figure 8 shows that there is a wavelength range where the hemispherical transmittance of P-polarized light and S-polarized light do not match, particularly at high temperatures, indicating polarization dependency.

[0088] Figures 5 and 6 show spectroscopic data for the rectilinear transmittance and hemispherical transmittance, respectively, of an element (EE1) containing a large amount of chiral material. Figure 5 shows that the rectilinear transmittance of P-polarized light and S-polarized light is nearly identical at both low and high temperatures, with almost no polarization dependency. However, the transmittance at low temperatures did not reach 50%. On the other hand, Figure 6 shows that the hemispherical transmittance of P-polarized light and S-polarized light is identical at both low and high temperatures, with almost no polarization dependency.

[0089] Figures 9 and 10 show spectroscopic data for the rectilinear transmittance and hemispherical transmittance of element (E3), respectively. These figures show that the rectilinear transmittance and hemispherical transmittance of P-polarized light and S-polarized light are consistent over a wide wavelength range at both low and high temperatures, indicating no polarization dependency. It is also clear that the element has high transmittance at low temperatures.

[0090] [2] Dependence of rectilinear transmittance and hemispherical transmittance on chiral material concentration The linear transmittance T of elements (E1) to (E4) and elements (EE1) to (EE2) without polarization d and hemispherical transmittance T h From the above, using the above formulas (F3) and (F4), the visible rectilinear transmittance T lum and solar hemispherical transmittance T sol11 and 12 were obtained. According to FIG. 11, the visible rectilinear transmittance T lum It can be seen that the solar hemispherical transmittance T at 20°C is higher than that of the element (EE2) with a liquid crystal layer containing no chiral material, reaching a maximum at a chiral material concentration of about 0.5 parts by mass, gradually decreasing as the chiral material concentration increases above 0.5 parts by mass, and becoming lower than that of the element (EE2) with a liquid crystal layer containing no chiral material when the chiral material concentration exceeds 1.1 parts by mass. sol is almost the same up to a chiral material concentration of 1.1 parts by mass in the liquid crystal layer, and gradually decreases as the chiral material concentration increases. sol It can be seen that the chiral agent concentration reaches a minimum at about 0.5 parts by mass, and gradually improves as the chiral agent concentration increases above 0.5 parts by mass.

[0091] Figure 13 shows the visible light transmittance T lum and solar hemispherical transmittance T sol (See Figures 11 and 12) lum and ΔT sol ) is a graph showing the chiral agent concentration dependency. It can be seen that all curves reach a maximum when the chiral agent concentration in the liquid crystal layer is around 0.5 parts by mass, and gradually decrease as the chiral agent concentration increases above 0.5 parts by mass. When no chiral agent is included, ΔT lum and ΔT sol are approximately 74% and approximately 20.3%, respectively, and the higher ΔT lum and ΔT sol The chiral material concentration at which ΔT lum For more than 0 parts by mass and 1.07 parts by mass or less, ΔT sol The content is more than 0 parts by mass and not more than 1.2 parts by mass.

[0092] [3] Degree of polarization of rectilinear transmittance and hemispherical transmittance From the transmittance of light with a wavelength of 800 nm of the elements (E1) to (E4) and the elements (EE1) to (EE2) at 20°C and 50°C, the polarization degree γ of the rectilinear transmittance was calculated using the following formula: dand the degree of polarization of the hemispherical transmittance γ h The graphs showing the chiral material concentration dependency are shown in Figures 14 and 15. gamma d =(T d,S -T d,P ) / (T d,S +T d,P ) gamma h =(T h,S -T h,P ) / (T h,S +T h,P )

[0093] From Figure 14, the degree of polarization of the rectilinear transmittance γ d It can be seen that decreases and approaches 0 as the chiral material concentration increases. For example, when the chiral material concentration is 1.1 parts by mass, the absolute value of the polarization degree of rectilinear transmittance is 0.05 or less and the absolute value of the polarization degree of hemispherical transmittance is 0.01 or less at 20°C and 50°C, which are steady values.

[0094] [4] Observation of the sample appearance under crossed Nicol arrangement with the element illuminated from the back side The elements (E3), (EE1), and (EE2) were sandwiched between two polarizing plates in a crossed Nicol arrangement and illuminated from behind with a light table to observe the direction and in-plane distribution of the anisotropy of the liquid crystal layer. Here, "crossed Nicol arrangement" means that the polarization directions of the two polarizing plates are arranged so that they are shifted by 90° from each other. When an image is observed with the element sandwiched between these two polarizing plates, the direction and strength of the optical anisotropy of the observed object appear as an in-plane distribution of light and dark.

[0095] Observation images of the sample appearances are shown in FIGS. 16, 17 and 18 in the order of elements (E3), (EE1) and (EE2). These images show that the element (E3) with a liquid crystal layer containing 0.53 parts by mass of chiral material (Figure 16) has less intensity non-uniformity, i.e., alignment irregularities, within the temperature-responsive photochromic element surface compared to the element (EE2) without chiral material (Figure 18). Similarly, the element (EE1) with a liquid crystal layer containing 1.62 parts by mass of chiral material (Figure 17) also shows that alignment irregularities are further suppressed, leading to more uniformity within the element surface. However, the element (EE1) has the problem of significant light scattering even when in a transparent state at 20°C, resulting in a smaller range of change in transmittance with temperature changes.

[0096] [5] Polarizing microscope observation of the device at 20°C and 50°C The light scattering in the cloudy state at 50°C is thought to be caused by an optically non-uniform structure within the liquid crystal layer, and this image was observed using a polarizing microscope. Two polarizers, one on the illumination side and one on the observation side, were installed in the housing of a Meiji Techno polarizing microscope "MT9430" (model name), and observations were made in a crossed Nicol configuration with the polarization directions at +45° and -45°, or 0° and 90°, respectively, relative to the rubbing direction of the element. A transparent temperature controller was installed on the sample stage of the microscope, and the element was placed on top of it and observed at 20°C and 50°C.

[0097] The images obtained by the polarizing microscope are shown in FIGS. 19, 20 and 21 for the elements (EE2), (E3) and (EE1) in that order.

[0098] Figure 19 shows images of element (EE2). (a) was taken at a temperature of 20°C with two polarizers oriented at 45° and -45° in a crossed Nicol configuration; (b) was taken at a temperature of 50°C with two polarizers oriented at 45° and -45° in a crossed Nicol configuration; (c) was taken at a temperature of 20°C with two polarizers oriented at 0° and 90° in a crossed Nicol configuration; and (d) was taken at a temperature of 50°C with two polarizers oriented at 0° and 90° in a crossed Nicol configuration. In the figures, the crosses "+" indicate the polarization directions of the two polarizers in the crossed Nicol configuration, and the double-headed arrows indicate the rubbing alignment direction. The scale bar length at the bottom left of (a) to (d) is 10 μm.

[0099] Figure 20 shows images of element (E3) taken with a polarizing microscope. (a) is taken at a temperature of 20°C, 45°C, and a crossed-Nicol arrangement with two polarizers oriented at 45° and -45°, respectively. (b) is taken at a temperature of 50°C, 45°C, and a crossed-Nicol arrangement with two polarizers oriented at 45° and -45°, respectively. (c) is taken at a temperature of 20°C, and a crossed-Nicol arrangement with two polarizers oriented at 0° and 90°, respectively. (d) is taken at a temperature of 50°C, and a crossed-Nicol arrangement with two polarizers oriented at 0° and 90°, respectively. In the figures, the crosses "+" indicate the polarization directions of the two polarizers in the crossed-Nicol arrangement, and the double-headed arrows indicate the rubbing alignment direction. The scale bar length in the lower left corners of (a) to (d) is 10 μm.

[0100] 21 shows images of the element (EE1) taken with a polarizing microscope. (a) is an image taken at 20°C with two polarizers oriented at 45° and −45° in a crossed Nicol configuration; (b) is an image taken at 50°C with two polarizers oriented at 45° and −45° in a crossed Nicol configuration; (c) is an image taken at 20°C with two polarizers oriented at 0° and 90° in a crossed Nicol configuration; (d) is an image taken at 50°C with two polarizers oriented at 0° and 90° in a crossed Nicol configuration; and (e) and (f) are low-magnification images of (a) and (b), respectively. In the figures, the crosses "+" indicate the polarization directions of the two polarizers in the crossed Nicol configuration, and the double-headed arrows indicate the rubbing alignment directions. The length of the scale bar at the bottom left of (a) to (d) is 10 μm, and the length of the scale bar at the bottom left of (e) and (f) is 100 μm.

[0101] 19 and 20, it can be seen that when the temperature of the element is raised from 20°C to 50°C, the uniform structure changes to a non-uniform structure on the optical wavelength scale (submicron to several microns in size), which is the microscopic origin of the change in the sample appearance from transparent to opaque as the temperature rises, and ultimately the temperature dependence of the transmittance. Furthermore, Figure 21 shows that at both 20°C and 50°C, domains larger than the optical wavelength scale (tens to hundreds of microns in size) are formed, which causes light scattering when the element is transparent at 20°C, and ultimately a decrease in transmittance. In this polarizing microscope observation, the crossed-Nicol polarizers were rotated not only at 45° to the rubbing direction but also at 0°. When rotated from 45° to 0°, the field of view of element (EE2) (Figure 19) became uniformly dark, suggesting that the low-molecular-weight liquid crystals and anisotropic polymer liquid crystals were aligned along the rubbing direction. On the other hand, in element (E3) (Figure 20), the field of view remained constant even when the polarizer was rotated, suggesting that the low-molecular-weight liquid crystals and anisotropic polymer liquid crystals were aligned in different directions due to the inclusion of an appropriate amount of chiral material in the liquid crystal layer. From these findings, it is believed that adding a chiral material to the liquid crystal layer creates a multi-domain orientation distribution of the low-molecular-weight liquid crystals and anisotropic polymer liquid crystals, reducing the areas of low alignment within the temperature-responsive switchable light-adjusting element and improving the temperature dependence of transmittance. [Industrial Applicability]

[0102] The temperature-responsive light-controlling element of the present invention has no polarization dependency of transmittance at 20°C and 50°C, and the polarization dependency of the transmittance change range at these temperatures is reduced. Therefore, for example, the element can be combined with a frame, a protective film, etc., and suitably used in optical shutters, light-controlling window glass, sensors, amenities, thermally actuated optical switches, photothermally writable memories, etc. [Explanation of symbols]

[0103] 1: Temperature-responsive dimming element 11: Liquid crystal layer 12: Base material layer 13: Base material layer 20: Integrating sphere detector

Claims

1. a liquid crystal layer containing a low molecular weight liquid crystal, a high molecular weight liquid crystal, and a chiral material; and a pair of base layers disposed on both sides of the liquid crystal layer; A temperature-responsive dimming element in which the content ratio of the chiral material contained in the liquid crystal layer is more than 0 parts by mass and not more than 1.1 parts by mass when the total amount of the low molecular weight liquid crystal and the high molecular weight liquid crystal is 100 parts by mass.

2. 2. The temperature-responsive photochromic element according to claim 1, wherein the chiral material is an alicyclic compound containing an ester bond.

3. 2. The temperature-responsive light control element according to claim 1, wherein the low-molecular-weight liquid crystal contains a compound whose phase transition temperature from a nematic phase to an isotropic phase is in the range of 20°C to 120°C.

4. 2. The temperature-responsive light-controlling element according to claim 1, wherein the polymer liquid crystal contains a structural unit derived from a monofunctional unsaturated compound having a cyanophenyl group.

5. The temperature-responsive light control element according to claim 1 , wherein the substrate layer has an alignment film on the liquid crystal layer side.

6. A method for producing the temperature-responsive dimming element according to claim 1, comprising: a composition disposing step of disposing a liquid crystal layer forming composition between a pair of substrates, the composition including a low molecular weight liquid crystal, a monomer capable of being polymerized to form a polymer liquid crystal, a chiral material, and a polymerization initiator; a liquid crystal layer forming step of irradiating the liquid crystal layer forming composition with a laser or ultraviolet light to form a liquid crystal layer containing the low molecular weight liquid crystal, the high molecular weight liquid crystal, and the chiral material between the substrates; A method for manufacturing a temperature-responsive dimming element, comprising the steps of:

7. The method for producing a temperature-responsive light-controlling element according to claim 6 , wherein the monomer comprises a monofunctional unsaturated compound having a cyanophenyl group.

8. A liquid crystal layer-forming composition used in the method for producing a temperature-responsive light control element according to claim 6, A liquid crystal layer-forming composition containing a low-molecular-weight liquid crystal, a monomer that polymerizes to form a polymeric liquid crystal, a chiral material, and a polymerization initiator.

9. A composite comprising the temperature-responsive dimming element according to claim 1 .

Images