Light-adjusting sheet, light-adjusting device, method for manufacturing light-adjusting sheet, and method for evaluating light-adjusting sheet

Abstract

To provide a lighting control sheet having antiglare properties, a lighting control device, a manufacturing method of a lighting control sheet, and an evaluation method of a lighting control sheet.SOLUTION: A lighting control sheet includes: an organic polymer layer 31P zoning a plurality of voids 31D; and a liquid crystal composition 31LC containing a liquid crystal compound LCM and filling the voids 31D. A drive of the liquid crystal compound LCM changes a transmittance of visible light. The lighting control sheet has an opaque state in which light transmittance at 365 nm is 0.1% to 5%. The liquid crystal composition 31LC contains a dichroic dye DP that exhibits a color in an opaque state.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a light control sheet including a liquid crystal composition, a light control device, a method for producing a light control sheet, and a method for evaluating a light control sheet. [Background technology]

[0002] The light-control sheet comprises a first transparent electrode layer, a second transparent electrode layer, and a light-control layer sandwiched between the first and second transparent electrode layers. The orientation state of the liquid crystal compound contained in the light-control layer changes the light transmittance of the light-control sheet in response to changes in the potential difference between the two transparent electrode layers. For example, when the orientation order of the liquid crystal compound is established, the light-control sheet exhibits high light transmittance. When the long axis direction of the liquid crystal compound is disordered, the light-control sheet exhibits low light transmittance.

[0003] A light control sheet that switches from transparent to opaque can protect the privacy of a target space. Clarity, parallel ray transmittance, transmitted image clarity, and haze are used as optical characteristic values ​​to evaluate privacy protection performance (see, for example, Patent Documents 1 to 3).

[0004] Clarity, parallel ray transmittance, and transmitted image clarity are the degree to which parallel rays from the target space are transmitted to the observation space, and indicate the clarity of the image viewed through the light control sheet. The privacy protection performance by image blurring is evaluated by clarity, parallel ray transmittance, and transmitted image clarity.

[0005] Haze is the ratio of diffuse transmittance to total light transmittance, and indicates the degree of cloudiness of an image seen through a light-control sheet. The privacy protection performance caused by the clouding of an image is evaluated by haze. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2019-200284 A [Patent Document 2] Patent No. 6669300 [Patent Document 3] International Publication No. 2018 / 021308 Summary of the Invention [Problem to be solved by the invention]

[0007] Optical property values ​​such as clarity and haze are measured using light rays across the entire visible light range. Changes in clarity largely reflect changes in transmission across the entire visible light range, but also reflect absorption, reflection, and scattering across the entire visible light range in addition to transmission to a greater extent. Changes in haze largely reflect changes in scattering across the entire visible light range, but also reflect absorption, reflection, and transmission across the entire visible light range in addition to scattering to a greater extent. Whether it is clarity, which largely reflects transmission, or haze, which largely reflects scattering, the visual effect of the light-controlling film predicted from the optical property values ​​of the light-controlling film ultimately reflects other optical effects across the entire visible light range.

[0008] In this regard, the visual perception through the light-adjusting sheet is also derived from a combination of transmission, absorption, reflection, and scattering in the entire visible light range. As described above, if the measurement uses light rays in the entire visible light range, the visual perception through the light-adjusting sheet is consistent with the perception predicted from the optical characteristic values ​​of the light-adjusting sheet, and the desired visual effect of protecting privacy is realized.

[0009] In recent years, as the range of application of light-controlling sheets has expanded, anti-glare properties for transmitted light are being sought as a new function to be added to light-controlling sheets. Anti-glare properties for transmitted light are a function that softens excessively strong transmitted light such as direct sunlight and high-brightness lighting. In order to improve anti-glare properties, it is necessary to increase scattering in the optical action and suppress forward scattering. On the other hand, the above-mentioned optical characteristic values ​​that reflect the combination of transmission, absorption, reflection, and scattering in the entire visible light range are not suitable for evaluating anti-glare properties, and as a result, the reality is that light-controlling sheets with added anti-glare properties have not yet been provided. [Means for solving the problem]

[0010] The light-adjusting sheet for solving the above problems comprises an organic polymer layer that defines a plurality of gaps, and a liquid crystal composition that contains a liquid crystal compound and fills the gaps, and is a light-adjusting sheet that changes the transmittance of visible light by driving the liquid crystal compound, and has a light transmittance of 365 nm in the light-adjusting sheet of 0.1% or more and 5% or less.

[0011] A light-adjusting sheet for solving the above problems comprises an organic polymer layer that defines a plurality of gaps, and a liquid crystal composition that contains a liquid crystal compound and fills the gaps, and a drive unit that changes the visible light transmittance in the light-adjusting sheet by changing the voltage applied to the liquid crystal compound, the drive unit changing the voltage so that the light transmittance at 365 nm in the light-adjusting sheet is 0.1% or more and 5% or less.

[0012] The visible light scattered forward by Mie scattering becomes weaker as the particle size with which the visible light collides is smaller than the wavelength of the visible light. In other words, the presence of many particles with a size smaller than the visible light wavelength enhances scattering over the entire visible light range and reduces the visible light scattered forward. The liquid crystal composition that fills the gaps defined by the organic polymer layer is the liquid crystal particles contained in the light control sheet, but the size of the gaps defined by the organic polymer layer is required to be such that the orientation state of the liquid crystal compound can be changed within the gaps.

[0013] In this regard, the light transmittance of a specific wavelength of 360 nm to 400 nm, for example, the light transmittance of 365 nm, largely reflects the degree of the presence of particles, and the particle size of the particles is smaller than the specific wavelength. And, particles having a particle size smaller than the specific wavelength enhance scattering over the entire visible light range and reduce visible light scattered forward. Also, particles having a particle size corresponding to the specific wavelength are the largest particles that can change the alignment state of the liquid crystal compound among particles that suppress forward scattering over the entire visible light range.

[0014] In this way, the light transmittance of a specific wavelength accurately represents the degree of particle presence. The size of the particles is such that the liquid crystal compound can change its orientation state, and the size is such that the scattering is increased over the entire visible light range and the forward scattering is suppressed. Therefore, if the light transmittance at 365 nm in the opaque state is 0.1% or more and 5% or less, it is possible to increase the scattering over the entire visible light range and suppress the forward scattering, and thus to impart the anti-glare properties of the transmitted light to the light control sheet.

[0015] In the above light controlling sheet, the liquid crystal composition may contain a dichroic dye that exhibits color in the opaque state. The orientation state of the dichroic dye follows the orientation state of the liquid crystal compound, thereby adding color to the opaque light control sheet. On the other hand, the gaps partitioned by the organic polymer layer must be large enough to change not only the orientation state of the liquid crystal compound but also the orientation state of the dichroic dye. In this regard, the light transmittance at a specific wavelength accurately represents the degree to which particles are present, and the particles include the largest particles among those that suppress forward scattering over the entire visible light range. As a result, in the above configuration in which the gaps are required to be large enough to change the orientation state of the dichroic dye, the effect of the light transmittance at 365 nm being 0.1% or more and 5% or less becomes even more remarkable.

[0016] In the above light controlling sheet, the liquid crystal composition may be liquid crystal particles phase-separated from the organic polymer layer, and the light transmittance may be 2% or more and 5% or less. The size of the liquid crystal particles that undergo phase separation in the organic polymer layer tends to become smaller as the number of liquid crystal particles increases. On the other hand, the size of the liquid crystal particles, i.e., the size of the gaps partitioned by the organic polymer layer, is required to be a dimension that allows the liquid crystal compound to change its orientation state within the gap. When the liquid crystal composition contains a dichroic dye, as described above, a larger gap is required by the size of the dichroic dye to change its orientation state.

[0017] In this respect, the above-mentioned light-adjusting sheet has a light transmittance of 2% or more at 365 nm, and therefore eliminates the configuration in which the number of voids is large but the size of the voids is too small for the dichroic dye to change its orientation state, and the size of the voids is a dimension suitable for a liquid crystal composition containing a dichroic dye. In addition, since the light-adjusting sheet has voids specialized for a liquid crystal composition containing a dichroic dye, it is possible to further enhance the above-mentioned effects in a configuration in which the liquid crystal composition contains a dichroic dye.

[0018] The light-controlling sheet may further include a spacer that exhibits the same color as the color of the dichroic dye. With this light-controlling sheet, the dichroic dye and the spacer exhibit the same color, so that the light-controlling sheet in the opaque state further enhances the anti-glare properties of visible light. In addition, the occurrence of granular unevenness due to scattering by the spacer can be suppressed in the light-controlling sheet in the opaque state.

[0019] In the light controlling sheet, the total light transmittance of the light controlling sheet in the opaque state may be 60% or less. Since the total light transmittance in the opaque state is 60% or less, the antiglare properties of transmitted light can be further improved.

[0020] The light-adjusting sheet may further include a first transparent electrode layer and a second transparent electrode layer, and the organic polymer layer may be located between the transparent electrode layers and transition from a transparent state to the opaque state when the voltage application between the transparent electrode layers is removed.

[0021] According to the above-mentioned light controlling sheet, it is possible to improve the anti-glare property of transmitted light in a normal type light controlling sheet. In addition, since the light transmittance of 365 nm can be evaluated in a state where the voltage application is released, the productivity and maintainability of the light controlling sheet with improved anti-glare property of transmitted light can be improved compared to a configuration that requires the application of voltage to evaluate the light transmittance.

[0022] The light-adjusting sheet may further include a first transparent electrode layer and a second transparent electrode layer, and the organic polymer layer may be located between the transparent electrode layers and transition from a transparent state to the opaque state upon application of a voltage between the transparent electrode layers.

[0023] According to the light-adjusting sheet, it is possible to improve the anti-glare property of transmitted light in the reverse-type light-adjusting sheet. In addition, even if an error occurs in the size of the voids in the organic polymer layer, which causes an error in the anti-glare property, the error can be corrected by the magnitude of the voltage applied between the transparent electrode layers.

[0024] A method for manufacturing a light-controlling sheet to solve the above problems comprises an organic polymer layer that defines a plurality of gaps, and a liquid crystal composition that contains a liquid crystal compound and fills the gaps, and the method changes the transmittance of visible light by driving the liquid crystal compound, the method including phase-separating liquid crystal particles composed of the liquid crystal composition from the organic polymer layer by polymerizing the photopolymerizable compound in a layer containing the liquid crystal composition and a photopolymerizable compound, and polymerizing the photopolymerizable compound so that the light-controlling sheet has an opaque state in which the light transmittance at 365 nm is 0.1% or more and 5% or less.

[0025] According to the above-mentioned method for producing a light-controlling sheet, it is possible to produce a light-controlling sheet having a light transmittance of 0.1% to 5% at 365 nm in an opaque state by polymerization of a photopolymerizable compound. This makes it possible to produce a light-controlling sheet that enhances the scattering of visible light by the light-controlling sheet and suppresses forward scattering, and thus has anti-glare properties.

[0026] To solve the above problems, a method for evaluating a light-adjusting sheet comprises an organic polymer layer that defines a plurality of voids, and a liquid crystal composition that contains a liquid crystal compound and fills the voids, and the method evaluates a light-adjusting sheet that changes the transmittance of visible light by driving the liquid crystal compound, and determines whether the light transmittance of a specific wavelength of 360 nm or more and 400 nm or less is within a specified range when the light-adjusting sheet is in an opaque state.

[0027] As described above, the light transmittance of a specific wavelength accurately represents the degree of particle presence. The size of the particles is such that the liquid crystal compound can change its orientation state, and the size is such that the scattering is increased over the entire visible light range, and the forward scattering is suppressed. If the method determines whether the light transmittance of a specific wavelength in an opaque state is within a predetermined range, it is possible to evaluate whether the light-controlling sheet increases the scattering of visible light and suppresses forward scattering. Effect of the Invention

[0028] According to the present invention, it is possible to provide a light control sheet having antiglare properties, a light control device, a method for manufacturing a light control sheet, and a method for evaluating a light control sheet. [Brief description of the drawings]

[0029] [Figure 1] FIG. 1 is a diagram showing a schematic configuration of a light control device according to an embodiment. [Diagram 2] FIG. 2 is a diagram showing a partial cross-sectional structure of a light adjusting sheet according to an embodiment. [Diagram 3] 1 is a table showing the evaluation results of examples and comparative examples of light controlling sheets. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] An embodiment of a light-adjusting sheet, a light-adjusting device, a method for manufacturing a light-adjusting sheet, and a method for evaluating a light-adjusting sheet will be described. First, the configuration of the light-adjusting device and the light-adjusting sheet will be described with reference to FIG. 1. Next, the internal configuration of the light-adjusting sheet will be described with reference to FIG. 2. Finally, a method for manufacturing a light-adjusting sheet, a method for evaluating a light-adjusting sheet, and examples of the light-adjusting sheet will be described.

[0031] The light-controlling sheet is attached to a transparent substrate. The transparent substrate is a glass body or a resin body. Examples of the transparent substrate are window glass installed in a moving body such as a vehicle or an aircraft, window glass installed in a building, and a partition installed in a vehicle or indoors. The surface to which the light-controlling sheet is attached is flat or curved. The light-controlling sheet may be sandwiched between two transparent substrates.

[0032] The driving type of the light-controlling sheet is either normal type or reverse type. A normal type light-controlling sheet transitions from an opaque state to a transparent state when a voltage is applied, and returns from the transparent state to the opaque state when the voltage application is removed. A reverse type light-controlling sheet transitions from a transparent state to an opaque state when a voltage is applied, and returns from the opaque state to the transparent state when the voltage application is removed. The normal type and reverse type have in common the fact that they are equipped with two transparent electrode layers and a light control layer. Below, the configuration and action of the reverse type will be mainly explained, and the configuration of the normal type that differs from the reverse type will be noted, while the configuration of the normal type that overlaps with the reverse type will be omitted.

[0033] [Light control device] 1, the light control device 10 includes a light control sheet 11 and a driving unit 12. The light control sheet 11 includes a light control layer 31, a first alignment layer 32, a second alignment layer 33, a first transparent electrode layer 34, a second transparent electrode layer 35, a first transparent support layer 36, and a second transparent support layer 37.

[0034] The light control layer 31 is located between the first alignment layer 32 and the second alignment layer 33. A first surface 31F of the light control layer 31 contacts the first alignment layer 32, and a second surface 31S of the light control layer 31 contacts the second alignment layer 33. The first alignment layer 32 is located between the light control layer 31 and the first transparent electrode layer 34, and contacts both the light control layer 31 and the first transparent electrode layer 34. The second alignment layer 33 is located between the light control layer 31 and the second transparent electrode layer 35, and contacts both the light control layer 31 and the second transparent electrode layer 35.

[0035] The first transparent electrode layer 34 is connected to the driving unit 12 through the first connection terminal 22A and the first wiring 23A. The first transparent electrode layer 34 is located between the first alignment layer 32 and the first transparent support layer 36, and contacts the first alignment layer 32 and the first transparent support layer 36. The second transparent electrode layer 35 is connected to the driving unit 12 through the second connection terminal 22B and the second wiring 23B. The second transparent electrode layer 35 is located between the second alignment layer 33 and the second transparent support layer 37, and contacts the second alignment layer 33 and the second transparent support layer 37.

[0036] The light control layer 31 includes an organic polymer layer 31P (see FIG. 2) and a liquid crystal composition 31LC (see FIG. 2). The organic polymer layer 31P defines voids 31D filled with the liquid crystal composition 31LC. The type of retention of the liquid crystal composition 31LC by the organic polymer layer 31P is any one selected from the group consisting of a polymer dispersion type, a polymer network type, and a capsule type.

[0037] The polymer dispersion type light control layer 31 has an organic polymer layer 31P that partitions a large number of isolated voids 31D, and holds a liquid crystal composition 31LC in the voids 31D dispersed in the organic polymer layer 31P. The polymer network type light control layer 31 has an organic polymer layer 31P that defines three-dimensional mesh-like voids 31D, and holds a liquid crystal composition 31LC in the interconnected mesh-like voids 31D. The capsule type light control layer 31 holds a liquid crystal composition 31LC in capsule-like voids 31D dispersed in the organic polymer layer 31P.

[0038] The first alignment layer 32 and the second alignment layer 33 each regulate the alignment direction of the liquid crystal compound LCM. The first alignment layer 32 and the second alignment layer 33 each appear as colorless and transparent or colored and transparent. The first alignment layer 32 and the second alignment layer 33 are vertical alignment films. The vertical alignment film aligns the long axis direction of the liquid crystal compound LCM with the thickness direction of the light control layer 31, and allows visible light to pass through the light control layer 31.

[0039] The material constituting the first alignment layer 32 and the second alignment layer 33 is an organic polymer compound or an inorganic oxide. The organic polymer compound is any one selected from the group consisting of polyimide, polyamide, polyvinyl alcohol, and cyanide compounds. The inorganic oxide is any one selected from the group consisting of silicon oxide, zirconium oxide, and silicone.

[0040] The first transparent electrode layer 34 and the second transparent electrode layer 35 are visually recognized as colorless and transparent or colored and transparent, respectively. The materials constituting the first transparent electrode layer 34 and the second transparent electrode layer 35 are conductive inorganic oxides, metals, or conductive organic polymer compounds, respectively. An example of the conductive inorganic oxide is any one selected from the group consisting of indium tin oxide, fluorine-doped tin oxide, tin oxide, and zinc oxide. The metal is gold or silver nanowires. An example of the conductive organic polymer compound is any one selected from the group consisting of carbon nanotubes and poly(3,4-ethylenedioxythiophene).

[0041] The first transparent support layer 36 and the second transparent support layer 37 are visually recognized as colorless and transparent or colored and transparent, respectively. The materials constituting the first transparent support layer 36 and the second transparent support layer 37 are organic polymer compounds or inorganic polymer compounds, respectively. An example of the organic polymer compound is any one selected from the group consisting of polyester, polyacrylate, polycarbonate, and polyolefin. An example of the inorganic polymer compound is any one selected from the group consisting of silicon oxide, silicon oxynitride, and silicon nitride.

[0042] The driving unit 12 is connected to the first transparent electrode layer 34 and the second transparent electrode layer 35 separately. The driving unit 12 applies a driving voltage between the first transparent electrode layer 34 and the second transparent electrode layer 35. The driving voltage is a voltage for changing the alignment state of the liquid crystal compound LCM. The driving unit 12 changes the alignment state of the liquid crystal compound LCM to switch the light control sheet 11 from one of a transparent state and an opaque state to the other. The opaque state has a lower parallel transmittance than the transparent state and also has a higher haze than the transparent state.

[0043] When the application of the driving voltage is released, the liquid crystal compound LCM receives an alignment regulation force from the first alignment layer 32 and the second alignment layer 33, and the long axis direction of the liquid crystal compound LCM is aligned with the thickness direction of the light control layer 31. As a result, the light control sheet 11 suppresses scattering in the light control layer 31 over the entire visible light range and becomes transparent.

[0044] When the driving voltage starts to be applied, the liquid crystal compound LCM is subjected to an orientation restricting force by the electric field, and the long axis direction of the liquid crystal compound LCM starts to move in a direction perpendicular to the electric field direction. At this time, the long axis direction of the liquid crystal compound LCM is restricted by the intermolecular interactions in the liquid crystal composition 31LC and the size of the voids 31D, and cannot move sufficiently, becoming disordered. As a result, the light control sheet 11 causes scattering in the light control layer 31 over the entire visible light range, and becomes opaque.

[0045] When the application of the driving voltage is released again, the liquid crystal compound LCM is released from the alignment force exerted by the electric field, and the liquid crystal compound LCM aligns its long axis direction with the thickness direction of the light control layer 31 according to the alignment force exerted by the first alignment layer 32 and the second alignment layer 33. This causes the light control sheet 11 to suppress scattering in the light control layer 31 over the entire visible light range, and to become transparent again.

[0046] If the light-adjusting sheet 11 is configured to switch between a transparent state and an opaque state based on a change in the alignment state of the liquid crystal compound LCM by application of a voltage, the first alignment layer 32 and the second alignment layer 33 may be omitted. In this case, the first surface 31F of the light-adjusting layer 31 contacts the first transparent electrode layer 34, and the second surface 31S of the light-adjusting layer 31 contacts the second transparent electrode layer 35. In other words, the driving type of the light-adjusting sheet 11 may be changed from a reverse type to a normal type.

[0047] In the case where the first alignment layer 32 and the second alignment layer 33 are omitted, when the application of the driving voltage is released, the liquid crystal compound LCM is not subjected to an alignment restraining force, and the long axis direction of the liquid crystal compound LCM becomes disordered. As a result, the light control sheet 11 causes scattering in the light control layer 31 over the entire visible light range, and becomes opaque.

[0048] When a driving voltage is applied, the liquid crystal compound LCM is subjected to an orientation control force by the electric field, and the long axis direction of the liquid crystal compound LCM is aligned along the electric field direction. As a result, the light controlling sheet 11 suppresses scattering in the light controlling layer 31 over the entire visible light range and becomes transparent.

[0049] When the application of the driving voltage is released again, the liquid crystal compound LCM loses the alignment force exerted by the electric field, and the long axis direction of the liquid crystal compound LCM becomes disordered. As a result, the light-controlling sheet 11 scatters light in the light-controlling layer 31 over the entire visible light range, and becomes opaque again.

[0050] [Light control sheet] As shown in FIG. 2, the light control layer 31 includes an organic polymer layer 31P, a liquid crystal composition 31LC, and a spacer SP. The organic polymer layer 31P defines a void 31D filled with the liquid crystal composition 31LC. The organic polymer layer 31P defines a plurality of voids 31D. The void 31D may be isolated from other adjacent voids 31D, or may be connected to other adjacent voids 31D. The voids 31D have two or more sizes, including a relatively large void 31H1 and a relatively small void 31H2. The shape of the void 31D is spherical, ellipsoidal, or irregular.

[0051] [Photopolymerizable compound] The organic polymer layer 31P is a cured product of a photopolymerizable compound. The photopolymerizable compound may be an ultraviolet curable compound or an electron beam curable compound. The photopolymerizable compound is compatible with the liquid crystal composition 31LC. When it is necessary to improve the controllability of the dimensions in the gap 31D, the photopolymerizable compound is preferably an ultraviolet curable compound. An example of the ultraviolet curable compound includes a polymerizable unsaturated bond at the end of the molecular structure. Alternatively, the ultraviolet curable compound includes a polymerizable unsaturated bond other than at the end of the molecular structure. The photopolymerizable compound is one type of polymerizable compound, or a combination of two or more types of polymerizable compounds.

[0052] The ultraviolet-curable compound is at least one selected from the group consisting of acrylate compounds, methacrylate compounds, styrene compounds, thiol compounds, and oligomers of each of these compounds.

[0053] The acrylate compounds include diacrylate compounds, triacrylate compounds, and tetraacrylate compounds. Examples of the acrylate compounds are butyl ethyl acrylate, ethylhexyl acrylate, and cyclohexyl acrylate. Examples of the methacrylate compounds are dimethacrylate compounds, trimethacrylate compounds, and tetramethacrylate compounds. Examples of the methacrylate compounds are N,N-dimethylaminoethyl methacrylate, phenoxyethyl methacrylate, methoxyethyl methacrylate, and tetrahydrofurfuryl methacrylate. Examples of the thiol compounds are 1,3-propanedithiol and 1,6-hexanedithiol. Examples of the styrene compounds are styrene and methylstyrene.

[0054] The lower limit of the content of the organic polymer layer 31P relative to the total amount of the organic polymer layer 31P and the liquid crystal composition 31LC is 20 mass %, and more preferably 30 mass %. The upper limit of the content of the organic polymer layer 31P relative to the total amount of the organic polymer layer 31P and the liquid crystal composition 31LC is 70 mass %, and more preferably 60 mass %.

[0055] The lower limit and upper limit of the content of the organic polymer layer 31P are within a range where the liquid crystal particles of the liquid crystal composition 31LC are phase-separated from the cured product of the photopolymerizable compound during the curing process of the photopolymerizable compound. When it is necessary to increase the mechanical strength of the organic polymer layer 31P, it is preferable that the lower limit of the content of the organic polymer layer 31P is high. When it is necessary to reduce the driving voltage of the liquid crystal compound LCM, it is preferable that the upper limit of the content of the organic polymer layer 31P is low.

[0056] [Liquid crystal composition] The liquid crystal composition 31LC is a polymer-dispersed liquid crystal composition. The liquid crystal composition 31LC contains a liquid crystal compound LCM and is filled in the gap 31D. The liquid crystal composition 31LC may contain a dichroic dye DP. The liquid crystal composition 31LC may contain a viscosity reducing agent, an antifoaming agent, an antioxidant, a weather resistance agent, and a solvent. Examples of the weather resistance agent include an ultraviolet absorber and a light stabilizer.

[0057] [Non-polymerizable liquid crystal compound] The liquid crystal compound LCM has a positive dielectric anisotropy, that is, the dielectric constant in the long axis direction is larger than the dielectric constant in the short axis direction of the liquid crystal compound LCM. Alternatively, the liquid crystal compound LCM has a negative dielectric anisotropy, that is, the dielectric constant in the long axis direction is smaller than the dielectric constant in the short axis direction of the liquid crystal compound LCM. The dielectric anisotropy of the liquid crystal compound LCM is appropriately selected based on the presence or absence of each alignment layer in the light control sheet 11 and the driving type.

[0058] The non-polymerizable liquid crystal compound is at least one selected from the group consisting of Schiff bases, azos, azoxys, biphenyls, terphenyls, benzoates, tolanes, pyrimidines, pyridazines, cyclohexane carboxylates, phenylcyclohexanes, biphenylcyclohexanes, dicyanobenzenes, naphthalenes, and dioxanes. The non-polymerizable liquid crystal compound is one type of liquid crystal compound or a combination of two or more types of liquid crystal compounds.

[0059] An example of the non-polymerizable liquid crystal compound is represented by the following formula (1). R 11 -A 11 -Z 11 -A 12 -Z 12 -A 13 -Z 13 -A 14 -R 12 …(1) R 11 R is a hydrogen atom or an alkyl group having 1 to 20 carbon atoms. 11 One or two or more non-adjacent methylene bonds contained in the alkyl group can be substituted with any bond selected from the group consisting of an oxygen atom, an ethylene bond, an ester bond, and a diether bond.

[0060] R 12 R is a hydrogen atom, a fluorine atom, a chlorine atom, a cyano group, a trifluoromethyl group, a trifluoromethoxy group, a difluoromethoxy group, or an alkyl group having 1 to 15 carbon atoms. 12One or two or more non-adjacent methylene bonds contained in the alkyl group can be substituted with any bond selected from the group consisting of an oxygen atom, an ethylene bond, an ester bond, and a diether bond.

[0061] A 11 , A 12 , A 13 , A 14 each independently represents a 1,4-phenylene group or a 2,6-naphthylene group. One or more hydrogen atoms of the 1,4-phenylene group or the 2,6-naphthylene group can be substituted with a fluorine atom, a chlorine atom, a trifluoromethyl group, or a trifluoromethoxy group. 11 , A 12 , A 13 , A 14 may each independently be a 1,4-cyclohexylene group, a 3,6-cyclohexenylene group, a 1,3-dioxane-2,5-diyl group, or a pyridine-2,5-diyl group. 13 , A 14 may each independently be a single bond.

[0062] Z 11 , Z 12 , Z 13 each independently represents any one selected from the group consisting of a single bond, an ester bond, a diether bond, an ethylene bond, a fluoroethylene bond, and a carbonyl bond.

[0063] The dichroic dye is driven by a guest-host system with the liquid crystal compound LCM as a host to exhibit color. The dichroic dye is at least one selected from the group consisting of polyiodine, azo compounds, anthraquinone compounds, naphthoquinone compounds, azomethine compounds, tetrazine compounds, quinophthalone compounds, merocyanine compounds, perylene compounds, and dioxazine compounds. The dichroic dye is one type of dye or a combination of two or more types of dyes.

[0064] When it is required to increase the light resistance and the dichroic ratio, the dichroic dye is at least one selected from the group consisting of an azo compound and an anthraquinone compound, and more preferably an azo compound.

[0065] The spacers SP are dispersed throughout the organic polymer layer 31P. The spacers SP determine the thickness of the light-controlling layer 31 around the spacers SP and make the thickness of the light-controlling layer 31 uniform. The spacers SP may be bead spacers or photospacers formed by exposing and developing a photoresist. The spacers SP may be colorless and transparent or colored and transparent. When the liquid crystal composition 31LC contains a dichroic dye, it is preferable that the color exhibited by the spacers SP is the same color as the color exhibited by the dichroic dye.

[0066] [Light transmittance of light control sheet] The light controlling sheet 11 satisfies the requirement that the light transmittance at a specific wavelength in an opaque state is 0.1% or more and 5% or less. In the normal type light controlling sheet 11, the light transmittance at a specific wavelength is 0.1% or more and 5% or less when the power supply is turned off. On the other hand, in the reverse type light controlling sheet 11, the driving unit 12 applies a driving voltage so that the light transmittance at a specific wavelength in an opaque state is 0.1% or more and 5% or less.

[0067] The specific wavelength is a single wavelength selected from the range of 360 nm to 400 nm. An example of the specific wavelength is 365 nm. The light transmittance at the specific wavelength is a value obtained using a total light transmittance measuring device conforming to JIS K 7361-1:1997 (ISO 1468-1) in an environment of 23±2°C, and the measuring device creates a parallel incident light beam of the specific wavelength by combining a light source and an optical system. That is, the light transmittance at the specific wavelength indicates the ratio of the transmitted light beam to the parallel incident light beam of the light control sheet 11, with the narrow-angle scattered light of the specific wavelength and the wide-angle scattered light of the specific wavelength being the transmitted light.

[0068] When the light controlling sheet 11 is required to have higher antiglare properties in the opaque state, it is preferable that the light controlling sheet 11 has a total light transmittance of 60% or less in the opaque state and a light transmittance of 2% to 5% at 365 nm. The total light transmittance is a value measured using a method in accordance with JIS K 7361-1:1997 (ISO 1468-1).

[0069] When the light controlling sheet 11 is required to have further improved antiglare properties in the opaque state, the light controlling sheet 11 contains a dichroic dye DP that exhibits black, and a spacer SP that exhibits black. It is preferable that the light transmittance at 365 nm in the opaque state is 2% or more and 5% or less.

[0070] Visible light scattered forward by Mie scattering is weakened as the particle size with which the visible light strikes is smaller than the wavelength of the visible light. In other words, the presence of many particles with sizes smaller than the wavelength of visible light enhances scattering across the entire visible light range and weakens the visible light scattered forward.

[0071] The liquid crystal composition 31LC filling the gap 31D defined by the organic polymer layer 31P is regarded as a liquid crystal particle contained in the light controlling sheet 11 when viewed from the visible light irradiated to the light controlling sheet 11. In other words, the liquid crystal particles are an aggregate of the liquid crystal composition. The size of the gap 31D defined by the organic polymer layer 31P is required to be a dimension that can change the alignment state of the liquid crystal compound LCM within the gap 31D.

[0072] The wavelength of 360 nm or more and 400 nm or less is the boundary region between visible light and ultraviolet light. The light transmittance of a specific wavelength in the range of 360 nm or more and 400 nm or less, for example, the light transmittance of 365 nm, largely reflects the degree of the presence of liquid crystal particles as viewed from visible light, and the particle size of the liquid crystal particles is smaller than the specific wavelength.

[0073] For example, the higher the light transmittance of a specific wavelength, the fewer the liquid crystal particles having a particle size smaller than the specific wavelength. Conversely, the lower the light transmittance of a specific wavelength, the more the liquid crystal particles having a particle size smaller than the specific wavelength. Liquid crystal particles having a particle size smaller than the specific wavelength enhance scattering over the entire visible light range and reduce visible light scattered forward. Furthermore, liquid crystal particles having a particle size corresponding to the specific wavelength are the largest among the liquid crystal particles that suppress forward scattering over the entire visible light range and can change the alignment state of the liquid crystal compound LCM.

[0074] In this way, the light transmittance of a specific wavelength accurately represents the degree of presence of liquid crystal particles. The size of the particles is such that the liquid crystal compound LCM can change its orientation state, and is also such that it enhances scattering over the entire visible light range and suppresses forward scattering. Therefore, if the light transmittance of a specific wavelength in an opaque state is 0.1% or more and 5% or less, it is possible to enhance scattering over the entire visible light range and suppress forward scattering, and thus impart anti-glare properties to the light-controlling sheet 11 for transmitted light.

[0075] The light-adjusting sheet 11 may have other functional layers as long as the light-adjusting sheet 11 is configured to switch between a transparent state and an opaque state based on a change in the alignment state of the liquid crystal compound LCM caused by application of a voltage. The other functional layers may be a gas barrier layer that suppresses the transmission of oxygen and moisture toward the light-adjusting layer 31, or an ultraviolet barrier layer that suppresses the transmission of ultraviolet light rays other than a specific wavelength toward the light-adjusting layer 31. The other functional layers may be a hard coat layer that mechanically protects each layer of the light-adjusting sheet 11, or an adhesive layer that enhances adhesion between layers in the light-adjusting sheet 11.

[0076] [Manufacturing method of light control sheet] The manufacturing method of the light control sheet 11 includes forming a coating film between the first transparent support layer 36 having the first alignment layer 32 and the first transparent electrode layer 34, and the second transparent support layer 37 having the second alignment layer 33 and the second transparent electrode layer 35. The coating film contains the above-mentioned photopolymerizable compound and liquid crystal composition 31LC. In the manufacturing method of the light control sheet 11 in which the first alignment layer 32 and the second alignment layer 33 are omitted, a coating film is formed between the first transparent support layer 36 having the first transparent electrode layer 34, and the second transparent support layer 37 having the second transparent electrode layer 35. The coating film contains the above-mentioned photopolymerizable compound and liquid crystal composition 31LC.

[0077] The coating film contains a polymerization initiator for initiating polymerization of the photopolymerizable compound. The polymerization initiator is at least one selected from the group consisting of a diketone compound, an acetophenone compound, a benzoin compound, a benzophenone compound, and a thioxanthone compound. The polymerization initiator may be one type of compound or a combination of two or more types of compounds. An example of the polymerization initiator is any one selected from the group consisting of benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, and cyclohexyl phenyl ketone.

[0078] The manufacturing method of the light controlling sheet 11 includes polymerizing a photopolymerizable compound in the coating film, thereby phase-separating liquid crystal particles made of the liquid crystal composition 31LC from the polymer. The light for polymerizing the photopolymerizable compound may be ultraviolet light or an electron beam. The light irradiated to the coating film may be irradiated toward the first transparent support layer 36, may be irradiated toward the second transparent support layer 37, or may be a combination of these.

[0079] Phase separation of liquid crystal particles made of liquid crystal composition 31LC proceeds through polymerization of the photopolymerizable compound and diffusion of liquid crystal composition 31LC. The polymerization speed of the photopolymerizable compound varies depending on the intensity of light irradiated to the photopolymerizable compound. The diffusion speed of the liquid crystal composition 31LC varies depending on the processing temperature during polymerization of the photopolymerizable compound. In phase separation of liquid crystal composition 31LC, the intensity of light irradiated to the photopolymerizable compound, the irradiation time, and the processing temperature during polymerization of the photopolymerizable compound are set so that the size of the liquid crystal particles is a desired size and the number of liquid crystal particles is a desired number. That is, in phase separation of liquid crystal composition 31LC, the intensity of light irradiated to the photopolymerizable compound, the irradiation time, and the processing temperature during polymerization of the photopolymerizable compound are set so that the size of the voids 31D is a desired size and the number of voids 31D is a desired number.

[0080] For example, when it is required to reduce the light transmittance of a specific wavelength, it is preferable to increase the intensity of the irradiated light so as to increase the polymerization rate of the photopolymerizable compound in order to reduce the size of the voids 31D and increase the number of the voids 31D. It is also preferable to lower the processing temperature so as to suppress the diffusion of the liquid crystal composition 31LC. On the other hand, when it is required to increase the light transmittance of a specific wavelength, it is preferable to lower the intensity of the irradiated light so as to decrease the polymerization rate of the photopolymerizable compound in order to increase the size of the voids 31D and reduce the number of the voids 31D. It is also preferable to increase the processing temperature so as to increase the diffusion of the liquid crystal composition 31LC.

[0081] [Evaluation method for light control film] The method for evaluating the light-adjusting sheet 11 involves irradiating the light-adjusting sheet 11 with parallel light rays of a specific wavelength between 360 nm and 400 nm, and determining whether the transmittance of the light of the specific wavelength that has passed through the light-adjusting sheet 11 is within a specific range. The specific wavelength may be one type, or may be two or more different wavelengths that are measured separately. When the specific wavelengths are two or more different wavelengths, the specific range of light transmittance used for the determination may be constant for each specific wavelength, or may be set separately for each specific wavelength.

[0082] As described above, the light transmittance of a specific wavelength accurately represents the degree of presence of liquid crystal particles whose particle size is smaller than that of the specific wavelength. Two different specific wavelengths cause the degree of presence of liquid crystal particles to differ from each other based on the particle size distribution of the liquid crystal particles. This makes it possible to grasp the degree of presence of liquid crystal particles in detail for each particle size.

[0083] For example, the specific wavelength may be 365 nm, may be other than 365 nm, or may be a combination of these. When the specific wavelength is 365 nm, the predetermined range of light transmittance may be 0.1% or more and 5% or less, or 2% or more and 5% or less. When the specific wavelength is two or more different wavelengths, the predetermined range of light transmittance used for the judgment may be 0.1% or more and 5% or less for each specific wavelength, or may be set separately for each specific wavelength.

[0084] [Example] Specific examples and comparative examples of the light control sheet 11 are shown below. Each example and comparative example is a normal type light control sheet 11 in which the first alignment layer 32 and the second alignment layer 33 are omitted. Then, a coating film containing a photopolymerizable compound and a liquid crystal composition 31LC was formed between a first transparent support layer 36 having a first transparent electrode layer 34 and a second transparent support layer 37 having a second transparent electrode layer 35, and the light control sheet 11 was obtained by polymerizing the photopolymerizable compound in the coating film.

[0085] The constituent materials used in the examples and comparative examples are shown below. First transparent electrode layer 34: indium tin oxide Second transparent electrode layer 35: indium tin oxide · First transparent support layer 36: polyethylene terephthalate film · Second transparent support layer 37: Polyethylene terephthalate film UV-polymerizable compound: Isobornyl acrylate : Pentaerythritol triacrylate : Urethane acrylate Polymerization initiator: 1-hydroxycyclohexyl phenyl ketone Liquid crystal compound LCM: Cyanobiphenyl compound Spacer SP: PMMA spherical particles

[0086] Example 1 A blue M1 anthraquinone compound (product name M-412: manufactured by Mitsui Fine Chemicals, Inc.) was used as the dichroic dye DP to prepare the coating liquid of Example 1. In this case, the ratio of the dichroic dye DP to the total amount of liquid crystal composition 31LC was 2 mass%, and the ratio of the polymerization initiator to the total amount of liquid crystal composition 31LC was 3 mass%. In addition, the ratio of the liquid crystal compound LCM to the total amount of liquid crystal composition 31LC was 55 mass%, and the ratio of the ultraviolet-polymerizable compound to the total amount of liquid crystal composition 31LC was 40 mass%.

[0087] A coating film having a thickness of 20 μm was formed on the first transparent electrode layer 34 using the coating liquid of Example 1, and white spacers SP having a particle size of 16 μm were scattered into the coating film. The coating film on which the spacers SP were scattered was then laminated with the first transparent electrode layer 34 and the second transparent electrode layer 35, and ultraviolet light of 365 nm was irradiated toward the first transparent support layer 36 to obtain the light control sheet 11 of Example 1. At this time, the intensity of the ultraviolet light was set to 10 mW / cm. 2 and the UV irradiation time was set to 100 seconds.

[0088] Example 2 A coating liquid of Example 2 was prepared using an anthraquinone compound blue S1 (product name SI-497: manufactured by Mitsui Fine Chemicals, Inc.) as the dichroic dye DP in the same blending ratio as the coating liquid of Example 1. The other conditions were the same as those of Example 1, and a light-controlling sheet 11 of Example 2 was obtained.

[0089] Example 3 A coating liquid of Example 3 was prepared using black Y1 (product name YH-428: manufactured by Mitsui Fine Chemicals Co., Ltd.), which is a mixture of anthraquinone compound and an azo compound, as the dichroic dye DP. At this time, the ratio of the dichroic dye DP to the total amount of liquid crystal composition 31LC was 3 mass%, and the ratio of the polymerization initiator to the total amount of liquid crystal composition 31LC was 3 mass%. In addition, the ratio of the liquid crystal compound LCM to the total amount of liquid crystal composition 31LC was 54 mass%, and the ratio of the ultraviolet-polymerizable compound to the total amount of liquid crystal composition 31LC was 40 mass%.

[0090] A coating film having a thickness of 20 μm was formed on the first transparent electrode layer 34 using the coating liquid of Example 3, and white spacers SP having a particle size of 16 μm were scattered in the coating film. The coating film on which the spacers SP were scattered was then laminated with the first transparent electrode layer 34 and the second transparent electrode layer 35, and ultraviolet light was irradiated toward the first transparent support layer 36 to obtain the light control sheet 11 of Example 3. At this time, the intensity of the ultraviolet light was increased compared to Example 1, and the irradiation time of the ultraviolet light was extended to polymerize the ultraviolet-polymerizable compound.

[0091] Example 4 A coating liquid of Example 4 was prepared using black S2 (product name S-428: manufactured by Mitsui Fine Chemicals Co., Ltd.), which is a mixture of anthraquinone compound and an azo compound, as the dichroic dye DP, in the same blending ratio as the coating liquid of Example 3. The other conditions were the same as those of Example 3, and the light control sheet 11 of Example 4 was obtained.

[0092] Example 5 The spacers SP of Example 3 were changed to black spacers SP with a particle size of 18 μm, and the other conditions were the same as in Example 3 to obtain a light controlling sheet 11 of Example 5.

[0093] Comparative Example 1 The azo compound red S3 (product name SI-426: manufactured by Mitsui Chemicals Fine Co., Ltd.) was used as the dichroic dye DP, the intensity of the ultraviolet light was lower than that of Example 1, and the other conditions were the same as those of Example 3, thereby obtaining the light-control sheet 11 of Comparative Example 1. Comparative Example 2 The azo compound Yellow S4 (product name SI-486: manufactured by Mitsui Chemicals Fine Co., Ltd.) was used as the dichroic dye DP, the intensity of the ultraviolet light was lower than that of Example 1, and the other conditions were the same as those of Example 3, thereby obtaining the light-control sheet 11 of Comparative Example 2.

[0094] [evaluation] The light control sheets 11 of Examples 1 to 5 and Comparative Examples 1 and 2 were evaluated for (a) transmittance at a specific wavelength, (b) light source transparency, (c) total light transmittance, (d) haze in an opaque state, (e) haze in a transparent state, and (f) granular unevenness. The evaluation results are shown in FIG.

[0095] (a) In measuring the transmittance at a specific wavelength, a total light transmittance measuring device was used, and a parallel incident light beam of 365 nm was formed by combining a UV irradiator (product name: 8322A, manufactured by CCS Co., Ltd.) with an optical system. Then, the transmittance at a specific wavelength was measured for each example and each comparative example using a method in accordance with JIS K 7361-1:1997 (ISO 1468-1), except that the wavelength of the parallel incident light beam was 365 nm.

[0096] (b) In the measurement of light source transparency of a specific wavelength, 365 nm light irradiated from a UV irradiator (product name: 8322A, manufactured by CCS Co., Ltd.) was visually evaluated through the opaque light-control sheet 11. At this time, a distance of 1 m was provided between the UV irradiator and the light-control sheet 11, and the amount of irradiated light was set to 1 W / cm2. 2 In Figure 3, the level where the light source was clearly recognized is marked with an "X", the level where the light source was not clearly recognized is marked with an "O", and the level where the position of the light source could not be identified is marked with an "◎".

[0097] (c) In the measurement of the total light transmittance, a white LED as a light source and an optical system were used to form a parallel incident light beam covering the entire visible light range. Then, the total light transmittance was measured for the opaque light control sheet 11 in each example and each comparative example using a method in accordance with JIS K 7361-1:1997 (ISO 1468-1).

[0098] (d) Haze was measured using a haze meter (product name: NDH7000SD, manufactured by Nippon Denshoku Industries Co., Ltd.). The haze was measured for the opaque light-control sheets 11 in each example and each comparative example using a method in accordance with JIS K 7136:2000 (ISO 14782). Similarly, the haze was measured for the transparent light-control sheets 11 in each example and each comparative example.

[0099] (e) Clarity was measured using a white LED light source and an optical system to create a parallel incident light beam across the entire visible light range, and a haze transparency meter (product name: Haze Guard i, manufactured by BYK-Gardner, Inc.) was used. Clarity is the amount of narrow-angle scattered light I measured by the haze transparency meter. R and the amount of parallel incident light I C The amount of narrow-angle scattered light was calculated using the following formula (2): The amount of narrow-angle scattered light is the amount of light detected in an integrating sphere at angles of -2.5° or more and 2.5° or less with respect to the optical axis of the parallel incident light beam. 100×(I C -I R ) / (I C +I R ) … Formula (2)

[0100] (f) In the measurement of granular unevenness, the light controlling sheet 11 in an opaque state was visually observed to judge whether or not granular unevenness was present on the light controlling sheet 11.

[0101] As shown in Fig. 3, it was confirmed that the light transmittance of the specific wavelength in each of Examples 1 to 5 satisfied the range of 0.1% or more and 5% or less. On the other hand, it was confirmed that the light transmittance of the specific wavelength in each of Comparative Examples 1 and 2 was 6% or more. It was also confirmed that the light source transparency of the specific wavelength, i.e., the antiglare property of the transmitted light, in each of Examples 1 to 5 was better than that of Comparative Examples 1 and 2. Note that high antiglare property at a specific wavelength indicates high antiglare property over the entire visible light range.

[0102] A comparison of the total light transmittance between Example 1 and Comparative Example 1 revealed that even if the total light transmittance was approximately the same, there was a difference in the antiglare properties. Also, a comparison of the total light transmittance between Example 2 and Comparative Example 1 revealed that even if the total light transmittance was relatively high, the antiglare properties could be relatively improved.

[0103] Comparison of haze in an opaque state between Example 2 and Example 3 revealed that even if the haze was the same, there was a difference in antiglare properties. Comparison of haze in an opaque state between Example 1 and Example 3 revealed that even if the haze was relatively low, the antiglare properties could be relatively improved. That is, even if the degree of image turbidity was relatively low, the antiglare properties could be relatively improved.

[0104] From the comparison of clarity in the opaque state between Examples 1 and 2 and Examples 3 to 5, it was also recognized that even in a configuration with relatively high clarity, the antiglare property can be relatively improved. In other words, it was also recognized that even in a configuration with relatively high image sharpness, the antiglare property can be relatively improved.

[0105] The change in haze measured using light in the entire visible range largely reflects the change in scattering in the entire visible range, but also reflects absorption, reflection, and transmission in the entire visible range in addition to scattering to a certain extent. The change in clarity measured using light in the entire visible range largely reflects the change in transmission in the entire visible range, but also reflects absorption, reflection, and scattering in the entire visible range in addition to transmission to a certain extent. Since the visual perception result through the light-adjusting sheet 11 is also derived from a combination of transmission, absorption, reflection, and scattering in the entire visible range, the result of image opacity through the light-adjusting sheet 11 is consistent with the result of image opacity predicted from the haze. Similarly, the clarity of the image through the light-adjusting sheet 11 is consistent with the clarity of the image predicted from the clarity.

[0106] On the other hand, as shown by the comparison of Examples 1 to 5, the antiglare property, which is contributed by the degree of scattering, particularly forward scattering, among the optical actions, cannot be adequately expressed by haze or clarity, which reflect the combination of optical actions in the entire visible light range. In this respect, it was recognized that the light transmittance of a specific wavelength accurately expresses the degree of the presence of particles that can suppress scattering, particularly forward scattering, and is an index value sufficient for evaluating the antiglare property of transmitted light in detail.

[0107] It was confirmed that the light transmittance at the specific wavelength in each of Examples 3 to 5 satisfied the range of 2% or more and 5% or less. On the other hand, it was confirmed that the light transmittance at the specific wavelength in each of Examples 1 and 2 was less than 1%. And it was confirmed that the antiglare properties of transmitted light in each of Examples 3 to 5 were better than those in each of Examples 1 and 2. That is, it was confirmed that even a configuration in which the light transmittance at the specific wavelength is 2% or more can obtain higher antiglare properties than a configuration in which the light transmittance at the specific wavelength is 1%.

[0108] The orientation state of the dichroic dye DP follows the orientation state of the liquid crystal compound LCM, thereby adding color to the opaque light control sheet 11. The gaps 31D partitioned by the organic polymer layer 31P need to be large enough to change not only the orientation state of the liquid crystal compound LCM but also the orientation state of the dichroic dye DP. If the light transmittance of the specific wavelength is 2% or more and 5% or less, the presence of small gaps 31D is suppressed compared to a configuration in which the light transmittance of the specific wavelength is less than 2%, and many gaps 31D large enough to change the orientation state of the dichroic dye DP can be present. As a result, it was found that the antiglare property of transmitted light can be further improved if the light transmittance of the specific wavelength is 2% or more and 5% or less.

[0109] A comparison of granular unevenness between Examples 1 to 4 and Comparative Examples 1 and 2 and Example 5 also revealed that granular unevenness can be suppressed if the color exhibited by the dichroic dye DP and the color exhibited by the spacer SP are the same color.

[0110] According to the above embodiment, the following effects can be obtained. (1) The light transmittance of a specific wavelength accurately represents the degree of the presence of liquid crystal particles. The size of the liquid crystal particles is such that the liquid crystal compound LCM can change its orientation state, and is also such that it enhances scattering over the entire visible light range and suppresses forward scattering. Therefore, if the light transmittance of a specific wavelength in an opaque state is 0.1% or more and 5% or less, it is possible to enhance scattering over the entire visible light range and suppress forward scattering, thereby adding anti-glare properties to the transmitted light to the light control sheet.

[0111] (2) When the size of the gap 31D is required to change the orientation state of the dichroic dye DP, the effect equivalent to the above item (1) becomes even more remarkable. (3) When the light transmittance at a specific wavelength is 2% or more, a configuration in which the number of voids 31D is large but the size of the voids 31D is small enough to change the alignment state of the dichroic dye DP is eliminated, and the size of the voids 31D becomes a dimension suitable for the liquid crystal composition 31LC containing the dichroic dye DP. Furthermore, since the light control sheet 11 has voids 31D specialized for the liquid crystal composition 31LC containing the dichroic dye DP, when the liquid crystal composition 31LC contains the dichroic dye DP, it is possible to further enhance the effect equivalent to the above (1).

[0112] (4) When the dichroic dye DP and the spacer SP have the same color, the occurrence of granular unevenness due to scattering by the spacer SP can be suppressed in an opaque light-controlling sheet.

[0113] (5) When the total light transmittance in the opaque state is 60% or less, it is possible to further improve the antiglare properties of transmitted light. (6) In the case of a normal type light-adjusting sheet 11, the light transmittance of a specific wavelength can be evaluated when the voltage application is removed, thereby improving the productivity and maintainability of the light-adjusting sheet 11 having enhanced anti-glare properties for transmitted light.

[0114] (7) With the reverse-type light controlling sheet 11, even if an error in the size of the gap 31D causes an error in the antiglare properties, the error can be corrected by adjusting the magnitude of the drive voltage.

[0115] (8) If the method determines whether the light transmittance of a specific wavelength in an opaque state is within a specified range, it becomes possible to evaluate whether the light-adjusting sheet 11 increases the scattering of visible light and suppresses forward scattering.

[0116] The above embodiment can be modified as follows. The liquid crystal composition 31LC may be configured to omit the dichroic dye DP. As described above, the light transmittance at a specific wavelength accurately represents the degree of presence of liquid particles that enhance scattering over the entire visible light range and suppress forward scattering. Therefore, even in a configuration in which the dichroic dye DP is omitted, it is possible to enhance scattering over the entire visible light range and suppress forward scattering as long as the light transmittance at a specific wavelength in the opaque state is 0.1% or more and 5% or less. In addition, it is possible to impart anti-glare properties for transmitted light to the light control sheet 11. [Explanation of symbols]

[0117] DP: Dichroic dye LCM…liquid crystal compound SP…Spacer 11...Light-adjusting sheet 12...Drive unit 31...Photochromic layer 32...First alignment layer 33...Second alignment layer 34...First transparent electrode layer 35...Second transparent electrode layer 36...First transparent support layer 37…Second transparent support layer 31P…Organic polymer layer 31D…Void 31LC…Liquid crystal composition

Claims

1. an organic polymer layer defining a plurality of voids; a liquid crystal composition that contains a liquid crystal compound and fills the gap; A light-controlling sheet which changes the transmittance of visible light by driving the liquid crystal compound, The light-adjusting sheet has an opaque state in which the light transmittance at 365 nm is 0.1% or more and 5% or less, the liquid crystal composition contains a dichroic dye that exhibits color in the opaque state, Dimming sheet.

2. the liquid crystal composition is liquid crystal particles phase-separated from the organic polymer layer, The light transmittance is 2% or more and 5% or less. The light controlling sheet according to claim 1 .

3. The color sensor further includes a spacer that exhibits the same color as the dichroic dye. The light controlling sheet according to claim 1 or 2.

4. The total light transmittance of the light-adjusting sheet in the opaque state is 60% or less. The light controlling sheet according to claim 1 .

5. A first transparent electrode layer; A second transparent electrode layer, the organic polymer layer is located between transparent electrode layers; The transparent state is changed to the opaque state by removing the voltage applied between the transparent electrode layers. The light controlling sheet according to claim 1 .

6. A first transparent electrode layer; A second transparent electrode layer, the organic polymer layer is located between transparent electrode layers; The transparent state is changed to the opaque state by applying a voltage between the transparent electrode layers. The light controlling sheet according to claim 1 .

7. a light control sheet including an organic polymer layer that defines a plurality of voids, and a liquid crystal composition that contains a liquid crystal compound and fills the voids; A driving unit that changes the transmittance of visible light in the light controlling sheet by changing the voltage applied to the liquid crystal compound, The driving unit changes the voltage so that the light-adjusting sheet is in an opaque state in which the light transmittance at 365 nm is 0.1% or more and 5% or less, the liquid crystal composition contains a dichroic dye that exhibits color in the opaque state, Dimmer.

8. A method for producing a light control sheet comprising an organic polymer layer that defines a plurality of voids, and a liquid crystal composition that contains a liquid crystal compound and fills the voids, the light control sheet changing a transmittance of visible light by driving the liquid crystal compound, comprising: a step of polymerizing the photopolymerizable compound in a layer containing the liquid crystal composition and the photopolymerizable compound to phase-separate liquid crystal particles made of the liquid crystal composition from the organic polymer layer; The photopolymerizable compound is polymerized so that the light-adjusting sheet has an opaque state in which the light transmittance at 365 nm in the light-adjusting sheet is 0.1% or more and 5% or less; the liquid crystal composition contains a dichroic dye that exhibits color in the opaque state, A method for manufacturing light-controlling sheets.

9. A method for evaluating a light-controlling sheet, comprising: an organic polymer layer that defines a plurality of voids; and a liquid crystal composition that contains a liquid crystal compound and fills the voids; and the light-controlling sheet changes a transmittance of visible light by driving the liquid crystal compound, comprising: the liquid crystal composition contains a dichroic dye that exhibits color when the light controlling sheet is in an opaque state, It is determined whether the light transmittance of the light-adjusting sheet in the opaque state at 365 nm, which is a specific wavelength of 360 nm to 400 nm, is 0.1% to 5%. How to evaluate light-adjusting sheets.

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