Light modulating sheet and method for manufacturing light modulating sheet

Abstract

This light modulating sheet comprises: a light modulating layer including a liquid crystal compound and a dichroic dye; and a first transparent electrode layer and a second transparent electrode layer, which are a pair of transparent electrode layers sandwiching the light modulating layer. When viewed from a position facing the surface of the light modulating sheet: the first transparent electrode layer includes a non-conductive portion extending linearly, and a conductive portion demarcated by the non-conductive portion; and a section having conductivity in the second transparent electrode layer overlaps each of the conductive portion and the non-conductive portion. The average transmittance of light in an infrared region in the light modulating sheet when in an opaque state is 64% or less.

Description

Light-adjusting sheet and method for manufacturing the light-adjusting sheet

[0001] The present disclosure relates to a light-controlling sheet and a method for manufacturing the light-controlling sheet.

[0002] The light-controlling sheet includes a light-controlling layer containing a liquid crystal composition and a pair of transparent electrode layers sandwiching the light-controlling layer. Each transparent electrode layer is supported by a transparent support layer on the side opposite the light-controlling layer. The orientation state of the liquid crystal composition changes depending on whether or not a voltage is applied to the transparent electrode layer, making it possible to switch between a transparent state in which light passes through the light-controlling layer and an opaque state in which light transmission through the light-controlling layer is suppressed by scattering or the like.

[0003] To improve design and expand functionality, a structure has been proposed in which a light-controlling sheet is divided into multiple regions, and each region can be switched between a transparent state and an opaque state (see, for example, Patent Document 1). For example, the light-controlling sheet is divided into multiple regions by cutting with a cutting device or by partially insulating the transparent electrode layer by laser irradiation.

[0004] JP 2018-60128 A

[0005] When dividing a light-controlling sheet into multiple regions using a cutting device, the transparent support layer located on the surface of the light-controlling sheet is also cut along with the transparent electrode layer. Therefore, it is necessary to protect the surface of the cut light-controlling sheet, and rough cuts can also lead to a poor appearance of the light-controlling sheet.

[0006] On the other hand, when dividing a light-controlling sheet into multiple regions using laser irradiation, the laser light passes through the transparent support layer, preventing cutting of the surface of the light-controlling sheet. However, the laser light also passes through the light-controlling layer, insulating both of the pair of transparent electrode layers. Therefore, for each divided region, wiring for applying voltage must be connected to each of the transparent electrode layers sandwiching the light-controlling layer. This increases the number of wirings, inevitably complicating the manufacturing of the light-controlling sheet and the control of voltage application.

[0007] One embodiment of a light-controlling sheet comprises a transparent polymer layer including a plurality of domains, a liquid crystal composition filling the domains, the liquid crystal composition including a liquid crystal compound and a dichroic dye, and a pair of transparent electrode layers, a first transparent electrode layer and a second transparent electrode layer, sandwiching the light-controlling layer. The light-controlling sheet changes the orientation of the liquid crystal compound and the dichroic dye in response to changes in the potential difference between the pair of transparent electrode layers, thereby switching from a colored opaque state to a transparent state. When viewed from a position facing the surface of the light-controlling sheet, the first transparent electrode layer includes linearly extending non-conductive portions and conductive portions separated by the non-conductive portions, and the conductive portions of the second transparent electrode layer overlap with each of the conductive portions and the non-conductive portions. The average transmittance of light in the infrared region of the light-controlling sheet in the opaque state is 64% or less.

[0008] One aspect of a method for manufacturing a light-controlling sheet includes forming a laminated sheet including a transparent polymer layer including a plurality of domains, a light-controlling layer including a liquid crystal composition that fills the domains, the liquid crystal composition including a liquid crystal compound and a dichroic dye, and a pair of transparent electrode layers, a first transparent electrode layer and a second transparent electrode layer, that sandwich the light-controlling layer; and irradiating the laminated sheet with an infrared laser from the side of the light-controlling layer where the first transparent electrode layer is located, to form linear non-conductive portions and conductive portions separated by the non-conductive portions in the first transparent electrode layer, wherein the average transmittance of light in the infrared region of the laminated sheet is 64% or less.

[0009] Fig. 1 is a diagram showing the cross-sectional structure of a light-adjusting sheet of one embodiment. Fig. 2 is a diagram showing the planar structure of the light-adjusting sheet of the embodiment. Fig. 3 is a diagram showing an enlarged view of a portion of the cross-sectional structure of the light-adjusting sheet of the embodiment. Fig. 4 is a diagram showing the structure of the light-adjusting layer of the light-adjusting sheet of the embodiment. Fig. 5 is a diagram showing a method for manufacturing the light-adjusting sheet of the embodiment.

[0010] An embodiment of a light-controlling sheet and a method for manufacturing the same will be described with reference to Figures 1 to 5. [Layer Structure of Light-Controlling Sheet] The layer structure of the light-controlling sheet will be described with reference to Figure 1. As shown in Figure 1, the light-controlling sheet 10 includes a light-controlling layer 20, a first transparent electrode layer 31, a second transparent electrode layer 32, a first transparent support layer 41, and a second transparent support layer 42. The light-controlling layer 20 is sandwiched between the first transparent electrode layer 31 and the second transparent electrode layer 32 and is in contact with these transparent electrode layers 31 and 32. The first transparent support layer 41 supports the first transparent electrode layer 31 on the side opposite the light-controlling layer 20 with respect to the first transparent electrode layer 31, and the second transparent support layer 42 supports the second transparent electrode layer 32 on the side opposite the light-controlling layer 20 with respect to the second transparent electrode layer 32.

[0011] The light-controlling layer 20 includes a transparent polymer layer having a large number of voids and a liquid crystal composition held in the voids. The light-controlling layer 20 has, for example, a polymer-dispersed liquid crystal or a polymer-network liquid crystal structure.

[0012] Each of the first transparent electrode layer 31 and the second transparent electrode layer 32 is conductive and transparent to light in the visible region. Examples of materials for the transparent electrode layers 31 and 32 include indium tin oxide, fluorine-doped tin oxide, tin oxide, zinc oxide, carbon nanotubes, poly(3,4-ethylenedioxythiophene), silver, and silver alloys.

[0013] Each of the first transparent support layer 41 and the second transparent support layer 42 is a base material that is transparent to light in the visible region. The material of the transparent support layers 41, 42 is, for example, a synthetic resin or an inorganic compound. Examples of synthetic resins include polyesters such as polyethylene terephthalate and polyethylene naphthalate, polyacrylates such as polymethyl methacrylate, polycarbonates, and polyolefins. Examples of inorganic compounds include silicon dioxide, silicon oxynitride, and silicon nitride.

[0014] The light-adjusting sheet 10 has a sheet region RS, a first end region RE1, and a second end region RE2. The sheet region RS contains the light-adjusting layer 20 and the layers sandwiching the light-adjusting layer 20. In other words, the sheet region RS is a region in which the light-adjusting layer 20 is sandwiched between a pair of transparent electrode layers 31 and 32.

[0015] The first end region RE1 and the second end region RE2 are located at the ends of the light-controlling sheet 10. In the first end region RE1, the first transparent support layer 41 and the first transparent electrode layer 31 extend from the sheet region RS. That is, in the first end region RE1, the first transparent electrode layer 31 is exposed from the light-controlling layer 20 and the second transparent electrode layer 32 and second transparent support layer 42. A first wiring section 51 is connected to the exposed surface of the first transparent electrode layer 31 to electrically connect the first transparent electrode layer 31 to a power source.

[0016] In the second end region RE2, the second transparent support layer 42 and the second transparent electrode layer 32 extend from the sheet region RS. That is, in the second end region RE2, the second transparent electrode layer 32 is exposed from the light control layer 20, the first transparent electrode layer 31, and the first transparent support layer 41. A second wiring section 52 is connected to the exposed surface of the second transparent electrode layer 32 to electrically connect the second transparent electrode layer 32 to a power source.

[0017] Each of the first wiring portion 51 and the second wiring portion 52 includes, for example, a conductive adhesive layer and a wiring substrate. The conductive adhesive layer is formed of, for example, an anisotropic conductive film (ACF), an anisotropic conductive paste (ACP), an isotropic conductive film (ICF), an isotropic conductive paste (ICP), or the like. The wiring substrate is, for example, a flexible printed circuit (FPC). Alternatively, each of the first wiring portion 51 and the second wiring portion 52 may have a structure in which a conductive material such as conductive tape and a conductor are joined by soldering.

[0018] The transparent electrode layers 31 and 32 are electrically connected to a control unit 55 via wiring units 51 and 52. The control unit 55 applies a driving voltage, which is an AC voltage for changing the alignment state of the liquid crystal compound, to the transparent electrode layers 31 and 32 via the wiring units 51 and 52. The light-modulating sheet 10, the control unit 55, and the wiring units 51 and 52 constitute a light-modulating device.

[0019] The light-controlling sheet 10 is attached to a transparent substrate, which is the object to which it is attached. The transparent substrate is a glass substrate or a resin substrate. Examples of transparent substrates include window glass installed in moving objects such as vehicles and aircraft, window glass installed in buildings, and partitions placed inside vehicles or indoors. The surface to which the light-controlling sheet 10 is attached is flat or curved. The light-controlling sheet 10 may also be sandwiched between two transparent substrates.

[0020] 2 and 3, the arrangement of the regions RS, RE1, RE2 and the wiring portions 51, 52 in the light controlling sheet 10 will be described. In Fig. 2, the sheet region RS is indicated by dots for ease of understanding.

[0021] 2 , the sheet area RS has a plurality of light control sections 60 and one or more insulating sections 61. When viewed from a position facing the surface of the light controlling sheet 10, the insulating sections 61 extend linearly and separate adjacent light control sections 60. In other words, the sheet area RS is divided into a plurality of light control sections 60 by the insulating sections 61.

[0022] 2 shows an example in which the dimming section 60 and the insulating section 61 extend in one direction, and three strip-like dimming sections 60 are partitioned by two insulating sections 61. However, the present invention is not limited to this example, and the number and shape of the dimming sections 60 and the insulating sections 61 are arbitrary as long as the dimming sections 60 are partitioned by linear insulating sections 61.

[0023] FIG. 3 shows the cross-sectional structure near the insulating portion 61. The first transparent electrode layer 31 has a conductive portion 33 and a non-conductive portion 35. The non-conductive portion 35 is a portion that has lost conductivity as a result of the first transparent electrode layer 31 being destroyed or modified by laser irradiation. In other words, the non-conductive portion 35 is a laser processing mark that extends linearly when viewed from a position facing the surface of the light-adjusting sheet 10. The conductive portion 33 is a portion that has not been irradiated with laser and is conductive. On the other hand, the second transparent electrode layer 32 does not have a non-conductive portion. In other words, the entire second transparent electrode layer 32 is the conductive portion 34.

[0024] In the sheet region RS, when viewed from a position facing the surface of the light controlling sheet 10, the portion where the conductive portion 33 is located is the light controlling portion 60, and the portion where the non-conductive portion 35 is located is the insulating portion 61. That is, in the light controlling portion 60, both the first transparent electrode layer 31 and the second transparent electrode layer 32 are conductive, and in the insulating portion 61, the first transparent electrode layer 31 is not conductive and the second transparent electrode layer 32 is conductive. The conductive portions 33 of the first transparent electrode layer 31 in adjacent light controlling portions 60 are insulated from each other by the non-conductive portion 35 located between them as the insulating portion 61.

[0025] Returning to FIG. 2 , the first end region RE1 has a first connection portion 70 and an end insulating portion 71. The first connection portion 70 extends continuously from the dimming portion 60 in the seat region RS. The conductive portion 33 of the first transparent electrode layer 31 is located in the first connection portion 70. The end insulating portion 71 extends linearly continuously from the insulating portion 61 in the seat region RS. The non-conductive portion 35 of the first transparent electrode layer 31 is located in the end insulating portion 71. The conductive portions 33 of the first transparent electrode layer 31 in adjacent first connection portions 70 are insulated from each other by the non-conductive portion 35 located between them as the end insulating portion 71.

[0026] In this way, a first connection portion 70 is provided for each dimming portion 60, and is electrically connected to the dimming portion 60 via the first transparent electrode layer 31, and adjacent first connection portions 70 are separated by end insulating portions 71. The first wiring portion 51 is connected to the first transparent electrode layer 31 of each first connection portion 70.

[0027] The second end region RE2 does not have an insulating portion. That is, the entire second transparent electrode layer 32 included in the sheet region RS and the second end region RE2 is a uniform conductive film. The second end region RE2 has a second connection portion 80. The second wiring portion 52 is connected to the second transparent electrode layer 32 of the second connection portion 80. In this way, one second wiring portion 52 is connected to the second end region RE2.

[0028] 2 shows a configuration in which the first end region RE1 and the second end region RE2 are arranged along opposing sides of the light controlling sheet 10, but the positional relationship between the first end region RE1 and the second end region RE2 may be set arbitrarily. In other words, the first connection portion 70 and the second connection portion 80 may be arranged along opposing sides of the light controlling sheet 10, or may have an arrangement different from this.

[0029] [Configuration of light-controlling layer] The detailed configuration of the light-controlling layer 20 will be described with reference to Fig. 4. Fig. 4 is a diagram schematically illustrating the laminated portion of the light-controlling layer 20 and the transparent electrode layers 31 and 32 in the cross-sectional structure of the light-controlling sheet 10, emphasizing the configuration of the light-controlling layer 20.

[0030] The light-controlling layer 20 includes a transparent polymer layer 21, a liquid crystal composition 22, and spacers 23. The transparent polymer layer 21 is a cured product of a photopolymerizable compound. The transparent polymer layer 21 defines a plurality of dispersed domains 21D therein. In other words, the domains 21D are voids. The domains 21D have, for example, a substantially spherical shape, a substantially ellipsoidal shape, or an irregular shape. The space within the domains 21D is filled with the liquid crystal composition 22.

[0031] The proportion of the transparent polymer layer 21 in the light-controlling layer 20 is preferably 20% by mass or more and 80% by mass or less, and more preferably 30% by mass or more and 60% by mass or less. When the proportion of the transparent polymer layer 21 is within the above range, the domain 21D is appropriately secured. Within the above range, the greater the proportion of the transparent polymer layer 21, the greater the mechanical strength of the transparent polymer layer 21 can be, and the smaller the proportion of the transparent polymer layer 21, the greater the driving voltage of the light-controlling sheet 10 can be.

[0032] The photopolymerizable compound that is the material of the transparent polymer layer 21 may be an ultraviolet-curable compound or an electron beam-curable compound. The photopolymerizable compound is compatible with the liquid crystal composition 22. When the photopolymerizable compound is an ultraviolet-curable compound, the controllability of the size of the domains 21D is improved. The photopolymerizable compound may be one type of polymerizable compound or a combination of two or more types of polymerizable compounds.

[0033] One example of a UV-curable compound contains a polymerizable unsaturated bond at the end of its molecular structure. Another example of a UV-curable compound contains a polymerizable unsaturated bond at a position other than the end of its molecular structure. UV-curable compounds include, for example, acrylate compounds, methacrylate compounds, thiol compounds, styrene compounds, and oligomers of these compounds. Acrylate compounds include diacrylate compounds, triacrylate compounds, and tetraacrylate compounds. Examples of acrylate compounds are butyl ethyl acrylate, ethylhexyl acrylate, and cyclohexyl acrylate. Methacrylate compounds include dimethacrylate compounds, trimethacrylate compounds, and tetramethacrylate compounds. Examples of methacrylate compounds are N,N-dimethylaminoethyl methacrylate, phenoxyethyl methacrylate, methoxyethyl methacrylate, and tetrahydrofurfuryl methacrylate. Examples of thiol compounds are 1,3-propanedithiol and 1,6-hexanedithiol. Examples of styrene compounds are styrene and methylstyrene.

[0034] The liquid crystal composition 22 includes a liquid crystal compound 22L and a dichroic dye 22P. The liquid crystal composition 22 may further include a viscosity reducer, an antifoaming agent, an antioxidant, a weathering agent, etc. Examples of the weathering agent include an ultraviolet absorber and a light stabilizer.

[0035] The liquid crystal compound 22L is a non-polymerizable compound. The dielectric constant of the liquid crystal compound 22L in the long axis direction is higher than the dielectric constant of the liquid crystal compound 22L in the short axis direction. That is, the liquid crystal compound 22L has positive dielectric anisotropy.

[0036] The liquid crystal compound 22L may be, for example, a Schiff base-based, azo-based, azoxy-based, biphenyl-based, terphenyl-based, benzoate ester-based, tolan-based, pyrimidine-based, pyridazine-based, cyclohexanecarboxylic acid ester-based, phenylcyclohexane-based, biphenylcyclohexane-based, dicyanobenzene-based, naphthalene-based, or dioxane-based compound. The liquid crystal compound 22L may be one type of liquid crystal compound or a combination of two or more types of liquid crystal compounds.

[0037] The dichroic dye 22P has an elongated molecular shape, and the absorbance in the visible region in the long axis direction of the molecule is greater than the absorbance in the short axis direction. The dichroic dye 22P exhibits a predetermined color when the long axis direction is approximately perpendicular to the direction of incident light. The color exhibited by the dichroic dye 22P is, for example, black or a color close to black. The dichroic dye 22P exhibits color when driven by a guest-host system using the liquid crystal compound 22L as a host.

[0038] Furthermore, the dichroic dye 22P has an absorption property for light in the infrared region. Light in the infrared region refers to light in the wavelength range of 780 nm or more and 2000 nm or less. Examples of the dichroic dye 22P include polyiodine, azo compounds, anthraquinone compounds, naphthoquinone compounds, azomethine compounds, tetrazine compounds, quinophthalone compounds, merocyanine compounds, perylene compounds, and dioxazine compounds. The dichroic dye 22P may be a single dye or a combination of two or more dyes. From the viewpoint of improving lightfastness and the dichroic ratio, the dichroic dye 22P is preferably at least one selected from the group consisting of azo compounds and anthraquinone compounds, and more preferably an azo compound.

[0039] The proportion of the dichroic dye 22P in the light-adjusting layer 20 is preferably 1% by mass or more and 10% by mass or less, and more preferably 2% by mass or more and 5% by mass or less. When the proportion of the dichroic dye 22P is 1% by mass or more, the difference in color of the light-adjusting sheet 10 between the transparent state and the opaque state becomes more clearly recognizable. In addition, the light-adjusting layer 20 is more likely to absorb light in the infrared region sufficiently. When the proportion of the dichroic dye 22P is 10% by mass or less, precipitation of particles formed by aggregation of the dichroic dye 22P can be suppressed.

[0040] The spacers 23 are dispersed throughout the transparent polymer layer 21. The spacers 23 determine the thickness of the photochromic layer 20 around the spacers 23, thereby making the thickness of the photochromic layer 20 uniform. The spacers 23 may be bead spacers or photospacers formed by exposing and developing a photoresist. The spacers 23 may be colorless and transparent, or colored and transparent, as long as they are translucent. The color of the colored and transparent spacers 23 is preferably the same color as the color of the dichroic dye 22P.

[0041] Because the thickness of the photochromic layer 20 roughly corresponds to the size of the spacers 23, the thickness of the photochromic layer 20 can be controlled by changing the average particle size of the spacers 23. As an example, the average particle size of the spacers 23 is 10 μm or more and 30 μm or less in terms of median diameter D50. In this case, the thickness of the photochromic layer 20 is 10 μm or more and 30 μm or less.

[0042] [Electrical Configuration of Dimming Device] A voltage signal input from the control unit 55 to each first wiring unit 51 is input to the first transparent electrode layer 31 of the dimming unit 60 that is electrically connected to the first connection unit 70 to which the first wiring unit 51 is connected, for each first wiring unit 51. That is, a voltage signal is input to the first transparent electrode layer 31 of each dimming unit 60 separately for each dimming unit 60.

[0043] On the other hand, the voltage signal input from the control unit 55 to the second wiring unit 52 is input to the second transparent electrode layer 32. That is, a voltage signal common to each dimming unit 60 is input to the second transparent electrode layer 32 of each dimming unit 60.

[0044] In the above configuration, the control unit 55 can control the application of a drive voltage to the dimming unit 60 for each dimming unit 60 by controlling the input of a voltage signal to the first transparent electrode layer 31 for each dimming unit 60 while inputting a common voltage signal to the second transparent electrode layer 32 of each dimming unit 60.

[0045] The light-adjusting section 60 switches between a transparent state and an opaque state based on a change in the alignment state of the liquid crystal composition 22. In the opaque state, the light-adjusting sheet 10 is colored, and in the transparent state, the light-adjusting sheet 10 is colorless or nearly colorless and transparent. In the opaque state, the total light transmittance of the light-adjusting sheet 10 is lower than in the transparent state, and the haze of the light-adjusting sheet 10 is higher than in the transparent state.

[0046] When no driving voltage is applied, the orientation of the major axes of the liquid crystal compound 22L and the dichroic dye 22P is random. Therefore, light incident on the light control section 60 is scattered in various directions in the light control layer 20. Furthermore, because the orientation of the major axes of the dichroic dye 22P is random, at least a portion of the dichroic dye 22P exhibits color. Therefore, when no driving voltage is applied, the light control section 60 is opaque and appears colored.

[0047] When the liquid crystal compound 22L has a positive dielectric anisotropy, application of a drive voltage orients the liquid crystal compound 22L and the dichroic dye 22P so that their major axes are aligned along the electric field direction. That is, the orientations of the liquid crystal compound 22L and the dichroic dye 22P change so that their major axes are aligned along the thickness direction of the light-adjusting layer 20. As a result, light scattering in the light-adjusting layer 20 and color development by the dichroic dye 22P are suppressed, and light is more easily transmitted through the light-adjusting section 60. Therefore, when a drive voltage is applied, the light-adjusting section 60 is in a transparent state.

[0048] [Characteristics of light-adjusting sheet] The optical characteristics of the light-adjusting sheet 10 will be described. The light-adjusting sheet 10 of this embodiment contains a dichroic dye 22P that absorbs light in the infrared region. Therefore, the light-adjusting sheet 10 in the opaque state has the ability to absorb light in the infrared region. In other words, the light-adjusting sheet 10 in the opaque state has reduced transmittance of light in the infrared region. Specifically, the average transmittance of light in the infrared region in the light-adjusting sheet 10 in the opaque state is 64% or less.

[0049] The average infrared light transmittance can be adjusted by the type and proportion of the dichroic dye 22P contained in the dimming layer 20. For example, when a dimming sheet 10 that exhibits black in an opaque state is constructed by mixing multiple types of dichroic dye 22P, the average infrared light transmittance can be reduced by increasing the proportion of dichroic dye 22P that exhibits high absorption in the long wavelength region of the visible range.

[0050] Furthermore, in the opaque state of the light-adjusting sheet 10, the total light transmittance of light in the visible region is preferably 20% or less, and more preferably 5% or less. On the other hand, in the transparent state of the light-adjusting sheet 10, the total light transmittance of light in the visible region is preferably 40% or more, and more preferably 50% or more. This allows for a clear difference in transparency between the transparent state and the opaque state.

[0051] [Method of manufacturing light-controlling sheet] A method of manufacturing the light-controlling sheet 10 will be described with reference to Fig. 5. First, a laminate is formed that includes the light-controlling layer 20, transparent electrode layers 31 and 32, and transparent support layers 41 and 42. At this time, the first transparent electrode layer 31 is a uniform conductive film in which no non-conductive portion 35 is formed.

[0052] In detail, first, a first transparent support layer 41 having a first transparent electrode layer 31 laminated thereon and a second transparent support layer 42 having a second transparent electrode layer 32 laminated thereon are prepared. The transparent electrode layers 31 and 32 are formed by a known film formation method such as sputtering.

[0053] Next, a coating film for forming the light-controlling layer 20 is formed between the first transparent electrode layer 31 and the second transparent electrode layer 32. The coating film contains a photopolymerizable compound, a liquid crystal compound 22L, a dichroic dye 22P, and a polymerization initiator for initiating polymerization of the photopolymerizable compound. Examples of the polymerization initiator include a diketone compound, an acetophenone compound, a benzoin compound, a benzophenone compound, a thioxanthone compound, and an oxime ester compound. The coating film may contain only a single type of polymerization initiator, or may contain multiple types of polymerization initiators. Note that the spacers 23 may be included in the coating liquid for forming the coating film, or may be dispersed in the coating film when the coating film is formed.

[0054] The laminate sandwiching the coating film is irradiated with light to polymerize the photopolymerizable compound, causing phase separation of the liquid crystal composition 22 and forming the light-controlling layer 20. The light that polymerizes the photopolymerizable compound is ultraviolet light or an electron beam. The light that polymerizes the photopolymerizable compound may be irradiated toward the first transparent support layer 41, may be irradiated toward the second transparent support layer 42, or may be irradiated toward both the first transparent support layer 41 and the second transparent support layer 42.

[0055] From the laminate obtained as described above, a laminate sheet 90 including the light-controlling layer 20, transparent electrode layers 31 and 32, and transparent support layers 41 and 42 is cut into the desired shape of the light-controlling sheet 10. In the laminate sheet 90, the orientations of the liquid crystal compound 22L and the dichroic dye 22P contained in the light-controlling layer 20 are random, and the laminate sheet 90 is opaque. The average infrared light transmittance of the laminate sheet 90 is 64% or less, similar to that of the light-controlling sheet 10 in an opaque state.

[0056] 5 , the laminate sheet 90 is irradiated with a laser beam La. In detail, a laser irradiation unit 100 of the laser device is disposed in a position facing the first transparent support layer 41, and the laser beam La is irradiated onto the regions of the laminate sheet 90 that will become the insulating portions 61 and 71 from the side where the first transparent electrode layer 31 is located with respect to the light-controlling layer 20.

[0057] The wavelength of the laser is in the infrared region. For example, the wavelength of the laser is preferably 1000 nm or more and 1200 nm or less. The laser medium is not particularly limited. For example, Nd:YAG laser, Nd:YVO ４ Laser, CO ２ A laser, a semiconductor laser, etc. can be used.

[0058] The laser La irradiated onto the laminated sheet 90 passes through the first transparent support layer 41 and enters the first transparent electrode layer 31. As a result, the first transparent electrode layer 31 is destroyed or modified, losing its conductivity, and a non-conductive portion 35 is formed.

[0059] Furthermore, a portion of the laser beam La that enters the first transparent electrode layer 31 enters the switchable layer 20. Here, the switchable layer 20 has the ability to absorb light in the infrared region due to the inclusion of the dichroic dye 22P. Therefore, the laser beam La that enters the switchable layer 20 is absorbed by the switchable layer 20. This prevents the laser beam La from passing through the switchable layer 20 and entering the second transparent electrode layer 32. As a result, the formation of a non-conductive portion in the second transparent electrode layer 32 is prevented, and an insulating portion 61 in which only the first transparent electrode layer 31 has lost conductivity can be suitably formed.

[0060] In general, the absorption spectrum of light in the infrared region derived from the dichroic dye 22P does not have a steep peak only at a specific wavelength in the infrared region, and if the average infrared light transmittance of the laminate sheet 90 is reduced, the transmittance decreases throughout the entire infrared region. If the average infrared light transmittance of the laminate sheet 90 is 64% or less, the laser beam La having a wavelength in the infrared region is suitably prevented from reaching the second transparent electrode layer 32 and processing the second transparent electrode layer 32. Furthermore, if the average infrared light transmittance of the laminate sheet 90 is 60% or less, the laser beam La is more suitably prevented from passing through the light-control layer 20 and entering the second transparent electrode layer 32.

[0061] Furthermore, since the absorption of light in the infrared region originating from the dichroic dye 22P is large around wavelengths of 1000 nm to 1500 nm, using a laser La with a wavelength of 1000 nm or more and 1200 nm or less can more effectively prevent the laser La from passing through the dimming layer 20 and entering the second transparent electrode layer 32.

[0062] After irradiation with the laser La, the first end region RE1 is formed by removing the switchable layer 20, the second transparent electrode layer 32, and the second transparent support layer 42 near the end of the laminate sheet 90. Furthermore, the second end region RE2 is formed by removing the switchable layer 20, the first transparent electrode layer 31, and the first transparent support layer 41 near the other end of the laminate sheet 90. Along with the formation of the first end region RE1 and the second end region RE2, a sheet region RS is formed.

[0063] This completes the formation of the light controlling sheet 10. The first wiring portion 51 is connected to each of the first connection portions 70 in the first end region RE1, and the second wiring portion 52 is connected to each of the second connection portions 80 in the second end region RE2.

[0064] In the above manufacturing method, because the laser is absorbed in the light control layer 20, it is easy to form the non-conductive portion 35 only in the first transparent electrode layer 31. As a result, in the light control sheet 10, a voltage signal can be input to the entire second transparent electrode layer 32 from a single second wiring portion 52. Therefore, compared to when both the first transparent electrode layer 31 and the second transparent electrode layer 32 are insulated for each light control portion 60 and wiring portions are provided in each transparent electrode layer 31, 32, that is, when separate voltage signals are input to the second transparent electrode layer 32 of each light control portion 60, it is possible to reduce the complexity of the arrangement of the wiring portions and the control of the input of the voltage signal.

[0065] Even if the laser is not absorbed in the light-controlling layer 20, it is not impossible to form a non-conductive portion in only one of the transparent electrode layers by controlling the laser irradiation conditions, but in this case, precise control of the laser focus, output, scanning speed, etc. is required. In contrast, in the present embodiment, the laser is absorbed in the light-controlling layer 20, which allows for more leeway in controlling the laser irradiation conditions, thereby reducing the burden required for manufacturing the light-controlling sheet 10.

[0066] [Examples] The above-mentioned light-controlling sheet will be described using specific examples and comparative examples. (Example 1) A liquid crystal compound, a dichroic dye, a photopolymerizable compound, and a polymerization initiator were mixed to produce a coating liquid for forming a light-controlling layer. Details of the materials are as follows. The proportions of each material in the coating liquid were 51% by mass of the liquid crystal compound, 4% by mass of the dichroic dye, 44% by mass of the photopolymerizable compound and polymerization initiator, and 1% by mass of the spacer. Liquid crystal compound: cyanobiphenyl compound Dichroic dye: black dichroic dye (YH-428, manufactured by Mitsui Fine Chemicals, Inc.) Photopolymerizable compound (ultraviolet curable compound): mixture of isobornyl acrylate, pentaerythritol triacrylate, and urethane acrylate Polymerization initiator: 1-hydroxycyclohexylphenyl ketone (Irgacure 184, manufactured by BASF Japan) Spacer: black spherical particles made of polymethyl methacrylate (particle size: 25 μm)

[0067] A first sheet was fabricated as a laminate of the first transparent support layer and the first transparent electrode layer by sputtering a first transparent electrode layer on the first transparent support layer. Similarly, a second sheet was fabricated as a laminate of the second transparent support layer and the second transparent electrode layer by sputtering a second transparent electrode layer on the second transparent support layer. Each of the first and second transparent support layers was made of polyethylene terephthalate and had a thickness of 125 μm. Each of the first and second transparent electrode layers was made of indium tin oxide (ITO) and had a thickness of 30 nm.

[0068] The coating liquid was applied to a first sheet to form a coating film on the first transparent electrode layer. The coating film had a thickness of 25 μm. A second sheet was then laminated to the first sheet on which the coating film had been formed, to obtain a laminate of the first sheet, the coating film, and the second sheet.

[0069] Subsequently, the first transparent support layer of the laminate was irradiated with ultraviolet light of 365 nm to form a light-controlling layer. The intensity of the ultraviolet light was 7.2 mW / cm. ２The irradiation time of the ultraviolet light was 120 seconds. As a result, a laminated sheet including a light control layer, a pair of transparent electrode layers, and a pair of transparent support layers was obtained.

[0070] The laminated sheet was irradiated with a laser from the side of the light-controlling layer where the first transparent support layer was located, to form non-conductive portions in the first transparent electrode layer. The laser irradiation conditions were as follows: Type: IR semiconductor laser Wavelength: 1064 nm Spot diameter: 30 μm This resulted in the production of the light-controlling sheet of Example 1, which had multiple light-controlling portions separated by insulating portions.

[0071] (Example 2) The light-controlling sheet of Example 2 was obtained using the same materials and process as in Example 1, except that the proportions of each material in the coating liquid for forming the light-controlling layer were changed to 52% by mass of liquid crystal compound, 3% by mass of dichroic dye, 44% by mass of photopolymerizable compound and polymerization initiator, and 1% by mass of spacer.

[0072] (Example 3) The proportions of each material in the coating liquid for forming the dimming layer were changed to 52% by mass of liquid crystal compound, 3% by mass of dichroic dye, 44% by mass of photopolymerizable compound and polymerization initiator, and 1% by mass of spacer, and the material of the first transparent electrode layer and the second transparent electrode layer was changed to a silver alloy. Except for this, the dimming sheet of Example 3 was obtained using the same materials and processes as in Example 1.

[0073] (Comparative Example 1) The proportions of each material in the coating liquid for forming the light-controlling layer were changed to 52% by mass of the liquid crystal compound, 0% by mass of the dichroic dye, 47% by mass of the photopolymerizable compound and polymerization initiator, and 1% by mass of the spacer, and the particle size of the spacer was changed to make the thickness of the light-controlling layer 22 μm. Except for this, the light-controlling sheet of Comparative Example 1 was obtained using the same materials and processes as in Example 1. In other words, the light-controlling sheet of Comparative Example 1 does not contain a dichroic dye.

[0074] (Comparative Example 2) The light-controlling sheet of Comparative Example 2 was obtained using the same materials and process as in Example 1, except that the proportions of each material in the coating liquid for forming the light-controlling layer were changed to 48% by mass of liquid crystal compound, 1.5% by mass of dichroic dye, 49.5% by mass of photopolymerizable compound and polymerization initiator, and 1% by mass of spacer.

[0075] (Evaluation) For the light-modulating sheets of each example and each comparative example, the average infrared light transmittance in the opaque state and the total light transmittance of light in the visible region in both the opaque and transparent states were measured. The average infrared light transmittance is the average transmittance of light with a wavelength of 780 nm or more and 2000 nm or less, and was measured using an infrared spectrometer. The total light transmittance was measured using a method in accordance with JIS K 7361-1. The opaque state is when an applied voltage is 0 V, and the transparent state is when an applied voltage is 60 V.

[0076] In addition, in the laser irradiation process during the production of the light-controlling sheets of each example and each comparative example, a processing evaluation was performed by checking whether a non-conductive portion could be formed only in the first transparent electrode layer of the first and second transparent electrode layers, and the range of laser scanning speeds capable of forming a non-conductive portion only in the first transparent electrode layer. In the processing evaluation, a case where a non-conductive portion could be formed only in the first transparent electrode layer and the range of laser scanning speeds capable of this processing was particularly good "A", a case where a non-conductive portion could be formed only in the first transparent electrode layer and the range of laser scanning speeds capable of this processing was narrow was good "B", and a case where a non-conductive portion could not be formed only in the first transparent electrode layer was poor "C". The range of laser scanning speeds when the evaluation was particularly good "A" was 3000 mm / s to 4500 mm / s, and the range of laser scanning speeds when the evaluation was good "B" was 3000 mm / s.

[0077] The composition of the light-controlling layer, the thickness of the light-controlling layer, and the material of the transparent electrode layer for each example and comparative example are shown in Table 1. Table 2 shows the average infrared light transmittance, total light transmittance, and processing evaluation for each example and comparative example.

[0078]

[0079]

[0080] As shown in Tables 1 and 2, in Examples 1 to 3 in which the average infrared light transmittance in the opaque state was 64% or less, the processing evaluation was good or particularly good, and it was possible to form a non-conductive portion only in the first transparent electrode layer. Furthermore, when the average infrared light transmittance was 60% or less, the processing evaluation was particularly good, and it was confirmed that the range of laser scanning speeds that can be used for processing was expanded.

[0081] On the other hand, in Comparative Examples 1 and 2, in which the average infrared light transmittance exceeded 64%, the processing evaluation was poor, and it was not possible to form a non-conductive portion only in the first transparent electrode layer. Even when the photochromic layer contains a dichroic dye, as in Comparative Example 2, it was confirmed that it was not possible to form a non-conductive portion only in the first transparent electrode layer when the average infrared light transmittance exceeded 64%. This suggests that in order to achieve an average infrared light transmittance of 64% or less, it is preferable for the photochromic layer to contain 3 mass% or more of the dichroic dye.

[0082] As described above in the embodiments and examples, the light-controlling sheet can achieve the following effects: (1) The light-controlling layer 20 contains a dichroic dye 22P that absorbs light in the infrared region, and the average infrared light transmittance of the light-controlling sheet 10 and laminated sheet 90 in an opaque state is 64% or less. With this configuration, infrared light is absorbed by the light-controlling layer, so it is easy to form a non-conductive portion 35 in only one of the two transparent electrode layers 31, 32 by using an infrared laser. This prevents an increase in the number of wiring lines required to connect the transparent electrode layers 31, 32 to a power source, and prevents the layout of the wiring lines and the control of the input of voltage signals from becoming complicated.

[0083] (2) By setting the ratio of the dichroic dye 22P in the photochromic layer 20 to 1% by mass or more and 10% by mass or less, the difference in color between the transparent state and the opaque state of the photochromic sheet becomes clearly recognizable, and precipitation of the dichroic dye and an increase in the manufacturing cost of the photochromic sheet can be suppressed. Furthermore, the photochromic layer 20 can easily absorb light in the infrared region.

[0084] (3) If the color of the dichroic dye 22P is black, the insulating portion 61, which is a laser processing mark, is less noticeable in the opaque state. (4) If the proportion of the transparent polymer layer 21 in the light-controlling layer 20 is 20% by mass or more and 80% by mass or less, a domain is appropriately secured in the transparent polymer layer 21, and the structure of the light-controlling layer 20 in which the liquid crystal composition 22 is dispersed in the transparent polymer layer 21 is suitably formed.

[0085] (5) The material of the transparent electrode layers 31, 32 includes indium tin oxide or a silver alloy. With the light-controlling sheet 10 and the laminated sheet 90 having such a configuration, it is possible to suitably process only one of the two transparent electrode layers 31, 32 using an infrared laser, as shown in the examples.

[0086] (6) The material of the transparent support layers 41, 42 contains polyethylene terephthalate. With the light-controlling sheet 10 and the laminated sheet 90 having such a configuration, it is possible to suitably process only one of the two transparent electrode layers 31, 32 using an infrared laser, as shown in the examples.

[0087] (Modifications) The above embodiment may be modified as follows: The following modifications may be combined with each other.

[0088] - As long as the average infrared light transmittance of the dimming sheet 10 and the laminated sheet 90 is 64% or less and the dimming sheet 10 is configured to be switched between a transparent state and an opaque state based on a change in the orientation state of the liquid crystal compound due to the application of a driving voltage, the layer structure of the dimming sheet 10 is not limited to the structure described in the above embodiment.

[0089] For example, the light-controlling sheet may include an alignment layer that controls the alignment of the liquid crystal compound. The light-controlling sheet may also include a functional layer having a desired function. The functional layer may be laminated on the transparent support layers 41, 42 and positioned at the outermost position of the light-controlling sheet, or may be positioned between layers, such as between the transparent electrode layers 31, 32 and the transparent support layers 41, 42. Examples of functional layers include a hard coat layer, an anti-blocking layer, a primer layer, a protective layer, and an index matching layer.

Claims

1. A light-adjusting sheet comprising: a transparent polymer layer including a plurality of domains; a liquid crystal composition filling the domains, the liquid crystal composition including a liquid crystal compound and a dichroic dye; and a pair of transparent electrode layers, a first transparent electrode layer and a second transparent electrode layer, sandwiching the light-adjusting layer; the orientation of the liquid crystal compound and the dichroic dye changes in response to a change in the potential difference between the pair of transparent electrode layers, thereby switching from a colored opaque state to a transparent state; when viewed from a position facing the surface of the light-adjusting sheet, the first transparent electrode layer includes a linearly extending non-conductive portion and a conductive portion separated by the non-conductive portion, and a conductive portion of the second transparent electrode layer overlaps with each of the conductive portion and the non-conductive portion; and the average transmittance of light in the infrared region through the light-adjusting sheet in the opaque state is 64% or less.

2. The light-controlling sheet according to claim 1, wherein the proportion of the dichroic dye in the light-controlling layer is from 1% by mass to 10% by mass.

3. The light-controlling sheet according to claim 1, wherein the proportion of the transparent polymer layer in the light-controlling layer is 20% by mass or more and 80% by mass or less.

4. The light control sheet according to claim 1, wherein the material of each of the first transparent electrode layer and the second transparent electrode layer includes indium tin oxide or a silver alloy.

5. The light-controlling sheet according to claim 1, comprising a pair of transparent support layers sandwiching the light-controlling layer and the pair of transparent electrode layers, the material of each of the pair of transparent support layers including polyethylene terephthalate.

6. A method for manufacturing a light-controlling sheet, comprising: forming a laminated sheet including a transparent polymer layer including a plurality of domains; a light-controlling layer including a liquid crystal composition filling the domains, the liquid crystal composition including a liquid crystal compound and a dichroic dye; and a pair of transparent electrode layers, a first transparent electrode layer and a second transparent electrode layer, sandwiching the light-controlling layer; and irradiating the laminated sheet with an infrared laser from the side of the light-controlling layer where the first transparent electrode layer is located, to form linear non-conductive portions and conductive portions separated by the non-conductive portions in the first transparent electrode layer, wherein the average transmittance of light in the infrared region in the laminated sheet is 64% or less.

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