JP7467993B2 - Light-adjusting sheet and light-adjusting device - Google Patents

Description

The present invention relates to a light control device equipped with a light control sheet.

The light control film comprises a first electrode layer, a second electrode layer, and a liquid crystal layer located between the first and second electrode layers. The first and second electrode layers are optically transparent to transmit visible light, and are supported on a light-transmitting film. The liquid crystal layer comprises a polymer network and a liquid crystal composition that fills voids in the polymer network. Changing the voltage applied between the electrode layers changes the light transmittance of the liquid crystal layer, thereby changing the light transmittance of the light control film (see, for example, Patent Document 1).

The environments in which light-control films are used are no longer limited to dry atmospheres with low relative humidity, but are increasingly being used in humid atmospheres with high relative humidity. When water penetrates the liquid crystal layer of a light-control film placed in a humid environment, the liquid crystal layer loses its ability to change the light transmittance.

There is a proposal to laminate (or pouch) electronic devices, such as LED-equipped tapes, organic EL elements, liquid crystal elements, electronic paper, film speakers, and sensors such as optical sensors, to obtain a laminate that prevents deterioration and damage to the embedded electronic devices. (See Patent Document 2)

JP 2018-40883 A JP 2019-42935 A

In manufacturing flexible light-control films using the roll-to-roll method, resin films such as PET are used as light-transmitting support films. The surface of a resin film cannot be completely flat, and has fine irregularities and wavy shapes. When various components are formed or laminated on such a resin film to produce a layered light-control film, the fine irregularities and wavy shapes originally possessed by the resin film may be followed or reflected by other components (or, in the worst case, amplified during the manufacturing process), resulting in distortion of the entire light-control film. If the light-control film has distortion, when it is applied to a highly rigid transparent support substrate or the glass of a building to form a rigid light-control device, air bubbles caused by the distortion remain, making it difficult to perform proper lamination processing, as well as causing a decrease in aesthetics and visibility, resulting in poor product quality.

The present invention aims to propose a light-controlling sheet that eliminates the effects of the minute irregularities and wavy shapes inherent in the resin film when a light-controlling film manufactured by the roll-to-roll method is laminated (or pouched) to form a light-controlling sheet, thereby reducing distortion and improving surface flatness, and to propose the configuration of a light-controlling device in a rigid form that uses the same.

The light controlling sheet according to the present invention is
a first transparent-coated substrate having a first bonding surface;
a second transparent-coated substrate having a second bonding surface;
A light control film is provided between the first joint surface and the second joint surface.
The light control film is
a first transparent electrode film including a first electrode layer and a first support film supporting the first electrode layer, the first support film being bonded to the first bonding surface;
a second transparent electrode film including a second electrode layer and a second support film supporting the second electrode layer, the second support film being bonded to the second bonding surface;
a liquid crystal layer including a liquid crystal composition filling a gap between the first transparent electrode film and the second transparent electrode film;
The light-control film further includes a transparent adhesive layer that bonds the light-control film to the first bonding surface and the light-control film to the second bonding surface, and the transparent adhesive layer has a thickness of 50 μm or more and 100 μm or less.

The transparent adhesive layer is preferably a hot melt type adhesive layer.

The first transparent-coated substrate and the second transparent-coated substrate each have a thickness of 25 μm or more and less than 100 μm;
It is preferable that the flatness according to JIS B 0621 (1984) is within +20% of the total thickness including the light control film and the transparent adhesive layer.

It is preferable that the first transparent coated substrate and the transparent adhesive layer, and the second transparent coated substrate and the transparent adhesive layer each have a thickness of 100 μm or less.

When the light control device is in a rigid form,
The above light control sheet,
The light control device is a post-attaching type in which the first transparent coated substrate or the second transparent coated substrate is bonded onto a glass substrate via a transparent adhesive layer.

The present invention provides a light-controlling sheet with reduced distortion and improved surface flatness by eliminating the effects of minute irregularities and wavy shapes inherent in the resin film, which is the light-transmitting support film that constitutes the flexible light-controlling film, and a rigid light-controlling device that uses the light-controlling sheet.

FIG. 1 is an explanatory diagram showing a light control device in which a light control sheet is applied to the surface of a glass plate. FIG. Cross-sectional view taken along line II-II in FIG. FIG. 13 is a partial cross-sectional view showing a light controlling sheet having a configuration that deviates from the present invention.

An embodiment of the light control sheet and light control device according to the present invention will be described. The light control sheet 10, which is the main part of the light control sheet and light control device, has a rectangular shape as shown in FIG. 2. The light control film 10 may be attached to a window of a moving object such as a vehicle or an aircraft. The light control sheet 10 may also be attached to a window of a building such as a house, a station, or an airport, a partition installed in an office, or a show window installed in a store. The object to which the light control sheet 10 is attached has various shapes such as a flat shape, a curved shape, or an irregular shape. The light control film 20 is attached to the object using an adhesive layer. The material constituting the adhesive layer is not particularly limited as long as it is a transparent layer having adhesive properties. An example of the adhesive layer is an OCA film (Optical Clear Adhesive film). The shape of the light control film 20, which is flexible and can be cut, can be changed to a geometric shape other than a rectangle, an irregular shape, or the like. Alternatively, it can be changed to a sheet shape with improved thickness and rigidity by joining it to another member. Hereafter, the light control film 20 processed into a sheet form will be referred to as the light control sheet 10.

[Light control sheet]
The light-adjusting sheet 10 includes a first transparent coating substrate 11, a second transparent coating substrate 12, a light-adjusting film 20, a power line 31, and a transparent adhesive layer 41. The first and second transparent coating substrates are laminated (laminate or pouched) onto the thin and flexible light-adjusting film 20 to form the light-adjusting sheet 10, which is provided with rigidity, barrier properties, mechanical strength, and the like (see FIG. 3).
Each of the transparent coating substrates 11 and 12 has a film shape. The thickness of each of the transparent coating substrates 11 and 12 is preferably 25 μm or more from the viewpoint of being able to improve the waterproofing of the light control film 20. The thickness of each of the transparent coating substrates 11 and 12 is preferably 100 μm or less from the viewpoint of being able to improve the light transmittance of the light control device. In addition, in a form in which the light control sheet 10 is applied to the glass of a building, a method called "water pasting" is sometimes adopted. In water pasting, detergent water is sprayed on both the sheet adhesive surface and the glass application surface, and the sheet is pasted while being pressed using a squeegee (spatula). A series of operations is performed in which the sheet is pressed to remove water before being peeled off, and the squeegee is pressed radially from the center so that the air between the application surface and the sheet is completely removed. In order to ensure "water drainage" by water pasting, it is necessary to set an upper limit for the thickness of each of the transparent coating substrates 11 and 12, so that it is preferable that the thickness is 100 μm or less from the viewpoint of improving workability.
Each of the transparent coating substrates 11, 12 is colorless and transparent and transmits visible light. Each of the transparent coating substrates 11, 12 is made of transparent resin or glass. Each of the transparent coating substrates 11, 12 can be changed to a colored transparent substrate that transmits a portion of visible light. Each of the transparent coating substrates 11, 12 preferably has a water absorption rate of 2% or less from the viewpoint of being able to improve the waterproofing of the light-controlling sheet 20. The water absorption rate is a value in accordance with JIS K 7209 (2000).

The resin constituting each transparent coating substrate 11, 12 is any one selected from the group consisting of polyethylene terephthalate, polyethylene naphthalate, polycarbonate, polypropylene, polystyrene, acrylic resins such as polymethyl methacrylate and methacrylic-styrene copolymer, nylon resins such as nylon 6 and nylon 66, and polyurethane. The water absorption rate of polyethylene terephthalate is 0.3%. The water absorption rate of polyethylene naphthalate is 0.3%. The water absorption rate of polycarbonate is 0.2%. The water absorption rate of nylon resins is 1.5% or more and 1.6% or less.

In order to improve the durability of the light control film 20 against ultraviolet rays, each transparent coating substrate 11, 12 can contain an ultraviolet absorbing agent. The resins constituting each transparent coating substrate 11, 12 can be changed to different types.

The light-control film 20 is located between the first transparent coated substrate 11 and the second transparent coated substrate 12. The entire light-control film 20 is covered by the first transparent coated substrate 11 in a plan view from a position opposite the first transparent coated substrate 11. The entire light-control film 20 is covered by the second transparent coated substrate 12 in a plan view from a position opposite the second transparent coated substrate 12.

The transparent adhesive layer 41 has a rectangular frame shape in a plan view from a position facing the second transparent coated substrate 12. The transparent adhesive layer 41 is bonded to the periphery of the first bonding surface 11A (see FIG. 3) of the first transparent coated substrate 11. The transparent adhesive layer 41 is bonded to the periphery of the second bonding surface 12A (see FIG. 3) of the second transparent coated substrate 12. The transparent adhesive layer 41 is bonded to the outer peripheral surface (end surface) of the light-adjusting sheet 20, and covers the entire end surface of the light-adjusting sheet 20.

The transparent adhesive layer 41 formed on the first bonding surface 11A side and the second bonding surface 12A side is made of an adhesive having a thickness of 50 μm or more and 100 μm or less. If the thickness of the transparent adhesive layer 41 is less than 50 μm, it is not preferable to obtain a light-control sheet 10 with reduced distortion and improved surface flatness by fully absorbing the fine unevenness and wavy shape originally possessed by the support film of the light-control film 20 and eliminating the influence thereof. In addition, it is not preferable because it affects the stiffness and firmness of each of the joined transparent coating substrates 11 and 12, not only inducing the occurrence of wrinkles but also increasing the construction load. If the thickness of the transparent adhesive layer 41 exceeds 100 μm, it is not preferable because it affects the flexibility of each of the transparent coating substrates 11 and 12, and when used as a light-control device, it is not preferable because it deteriorates the followability to the attachment surface (glass window, etc.). In addition, an excessively thick transparent adhesive layer 41 leads to a decrease in transparency and translucency. Setting the thickness of the transparent adhesive layer 41 within the above range is also advantageous in ensuring that water drains without causing dents or rippling in the support film of the light control film 20 during the water application process.

When a hot melt type adhesive is used, it is composed of ingredients such as resins, waxes, plasticizers, tackifiers, antioxidants, heat stabilizers and fillers. Resins include polyethylene, polyamide, polyvinyl butyral, polyvinyl acetate and ethylene-vinyl acetate copolymers. Waxes include petroleum-based (paraffin wax, etc.) and plant-based (japanese wax, white wax, beeswax, etc.). Plasticizers include phthalate esters such as diphenyl phthalate, dihexyl phthalate and dicyclohexyl phthalate, phosphate esters, chlorinated paraffin and petroleum-based plasticizers. Specific examples of tackifiers include butyral resin, polyisobutylene, acrylonitrile resin, and petroleum-based resin; antioxidants include dilauryl thiodipropionate, 2,6-t-cresol, p-octylphenol, sodium benzoate, and calcium stearate; and fillers include talc, clay, calcium carbonate, barium carbonate, and baryta.

The power line (not shown) is separately connected to the first electrode layer 22M (see FIG. 3) and the second electrode layer 23M (see FIG. 3) of the light control film 20. The power line includes separate conductive adhesive layers such as anisotropic conductive films bonded to each electrode layer 22M, 23M, and a single flexible printed substrate bonded to each conductive adhesive layer. The power line can be modified to include separate conductive paste layers bonded to each electrode layer 22M, 23M, separate conductive tapes bonded to each conductive paste layer, and separate lead wires bonded to each conductive tape.

The connection between the first electrode layer 22M and the power line is covered by the first transparent covering substrate 11. The connection between the second electrode layer 23M and the power line is covered by the second transparent covering substrate 12. The power line is connected to a drive device located outside the dimming device and to the dimming sheet 20 through a part of the transparent adhesive layer 41. The power line applies a drive voltage for driving the dimming device from the drive device between the first electrode layer 22M and the second electrode layer 23M.

As shown in FIG. 3, the first transparent coated substrate 11 has a first bonding surface 11A. The second transparent coated substrate 12 has a second bonding surface 12A. The light-control film 20 is located between the first bonding surface 11A of the first transparent coated substrate 11 and the second bonding surface 12A of the second transparent coated substrate 12. The first bonding surface 11A and the light-control sheet 20 are bonded with a transparent adhesive. The second bonding surface 12A and the light-control film 20 are also bonded with a transparent adhesive.

The transparent adhesive layer 41 is bonded to the first bonding surface 11A, the second bonding surface 12A, and the end surface 20E of the light control film 20 (see the partially enlarged view of FIG. 3). The transparent adhesive that bonds the first bonding surface 11A to the light control sheet 20 and the transparent adhesive that bonds the second bonding surface 12A to the light control film 20 are bonded to the transparent adhesive layer 41. The transparent adhesive that bonds the first bonding surface 11A to the light control film 20 and the transparent adhesive that bonds the second bonding surface 12A to the light control film 20 are integral with the transparent adhesive layer 41. The main component of the transparent adhesive that bonds the first bonding surface 11A to the light control film 20 and the main component of the transparent adhesive that bonds the second bonding surface 12A to the light control film 20 are the same type of resin as the main component of the transparent adhesive that constitutes the transparent adhesive layer 41. The main component is the component that has the highest blending ratio among the components that constitute the member.

The transparent adhesive that bonds the first bonding surface 11A and the light-adjusting film 20, and the transparent adhesive that bonds the second bonding surface 12A and the light-adjusting film 20 can be changed to a separate material from the transparent adhesive layer 41. The transparent adhesive that bonds the first bonding surface 11A and the light-adjusting sheet 20, the transparent adhesive that bonds the second bonding surface 12A and the light-adjusting film 20, and the transparent adhesive that constitutes the transparent adhesive layer 41 can be changed to different types of resins. If the main component of the transparent adhesive that bonds the first bonding surface 11A and the light-adjusting film 20, the main component of the transparent adhesive that bonds the second bonding surface 12A and the light-adjusting film 20, and the main component of the transparent adhesive that constitutes the transparent adhesive layer 41 are the same type of resin, it is possible to increase the adhesion between them.

[Light control sheet]
The light control film 20 includes a first support film 22T, a first electrode layer 22M, a liquid crystal layer 21, a second support film 23T, and a second electrode layer 23M. The first support film 22T and the first electrode layer 22M constitute a first transparent electrode film. The second support film 23T and the second electrode layer 23M constitute a second transparent electrode film.
The first support film 22T is bonded to the first bonding surface 11A with a transparent adhesive. The first support film 22T supports the first electrode layer 22M on a side surface located opposite the first bonding surface 11A. The second support film 23T is bonded to the second bonding surface 12A with a transparent adhesive. The second support film 23T supports the second electrode layer 23M on a side surface located opposite the second bonding surface 12A.

Each support film 22T, 23T has a film shape thinner than each transparent coated substrate 11, 12. The thickness of each support film 22T, 23T is preferably 20 μm or more from the viewpoint of improving the handleability of the light control film 20. The thickness of each support film 22T, 23T is preferably 200 μm or less from the viewpoint of improving the light transmittance. Each support film 22T, 23T is colored and transparent, which transmits a portion of visible light, or colorless and transparent, which transmits visible light.

Each of the support films 22T, 23T is made of a transparent resin. The resin constituting each of the support films 22T, 23T is any one selected from the group consisting of polyethylene terephthalate, polyethylene naphthalate, polycarbonate, polypropylene, polystyrene, acrylic resin, nylon resin, polyurethane, polyethylene, polyvinyl alcohol, polyvinyl chloride, polyimide, polysulfone, cycloolefin polymer, and triacetyl cellulose. The resin constituting each of the support films 22T, 23T can be changed to a different type.

Each electrode layer 22M, 23M has visible light transparency and electrical conductivity. Each electrode layer 22M, 23M is located on the entire side of a separate support film 22T, 23T. The thickness of each electrode layer 22M, 23M is preferably 0.1 μm or more from the viewpoint of improving electrical conductivity. The thickness of each electrode layer 22M, 23M is preferably 10 μm or less from the viewpoint of improving light transparency.

The material constituting each of the electrode layers 22M and 23M is any one selected from the group consisting of indium tin oxide, fluorine-doped tin oxide, tin oxide, zinc oxide, carbon nanotubes, poly(3,4-ethylenedioxythiophene), and silver alloy thin film.

The liquid crystal layer 21 is located between the first electrode layer 22M and the second electrode layer 23M. The liquid crystal layer 21 fills the entire space between the first electrode layer 22M and the second electrode layer 23M. The end faces of the liquid crystal layer 21 are flush with the end faces of the electrode layers 22M, 23M and the end faces of the support films 22T, 23T. The thickness of the liquid crystal layer 21 is preferably 10 μm or more from the viewpoint of improving the opacity of the liquid crystal layer 21. The thickness of the liquid crystal layer 21 is preferably 100 μm or less from the viewpoint of improving the transparency of the liquid crystal layer 21.

The liquid crystal layer 21 contains a liquid crystal composition. An example of the liquid crystal molecules contained in the liquid crystal composition is one selected from the group consisting of Schiff base type, azo type, azoxy type, biphenyl type, terphenyl type, benzoic acid ester type, tolan type, pyrimidine type, cyclohexane carboxylate type, phenylcyclohexane type, and dioxane type. The liquid crystal layer 21 can contain a dye having a predetermined color that does not interfere with the movement of the liquid crystal molecules depending on the presence or absence of voltage application to the liquid crystal layer 21.

The liquid crystal layer 21 has a polymer network that fills the entire gap between the first electrode layer 22M and the second electrode layer 23M. The liquid crystal composition is held in the voids of the polymer network. The type of holding the liquid crystal composition is any one selected from the group consisting of a polymer network type, a polymer dispersion type, and a capsule type. The polymer network type has a polymer network having a three-dimensional mesh shape, and holds the liquid crystal composition in the voids of the polymer network. The polymer dispersion type has a large number of isolated voids in the polymer network, and holds the liquid crystal composition in the voids dispersed in the polymer network. The capsule type holds a capsule-shaped liquid crystal composition in the polymer network.

The liquid crystal layer 21 includes spacers 21P dispersed throughout the liquid crystal layer 21. The spacers 21P have the function of maintaining the thickness of the liquid crystal layer 21 constant. The spacers 21P have a spherical shape with an average particle size approximately equal to the thickness of the liquid crystal layer 21. The material constituting the spacers 21P is either a transparent inorganic material such as silicon oxide or a transparent resin material such as an acrylic resin. The compressive fracture strength of the spacers 21P is preferably 1 MPa or more from the viewpoint of maintaining the thickness of the liquid crystal layer 21 when each transparent coated substrate 11, 12 is bonded to the light control film 20.

The light control film 20 may have functional layers other than the liquid crystal layer 21, the electrode layers 22M, 23M, and the support films 22T, 23T.

An example of a functional layer is a gas barrier layer or an ultraviolet barrier layer that protects the liquid crystal layer 21 and each electrode layer 22M, 23M. The gas barrier layer is located between each support film 22T, 23T and each transparent coated substrate 11, 12, or between each support film 22T, 23T and each electrode layer 22M, 23M.

An example of a functional layer is an alignment layer or a polarizing layer that contributes to controlling light transmittance. The alignment layer is located between each electrode layer 22M, 23M and the liquid crystal layer 21. The polarizing layer is located between each support film 22T, 23T and each transparent coated substrate 11, 12, or between each support film 22T, 23T and each electrode layer 22M, 23M.

An example of a functional layer is a hard coat layer, which enhances the strength and heat resistance of the light-control film 20. The hard coat layer is located between each of the support films 22T, 23T and each of the transparent coated substrates 11, 12. Furthermore, an example of a functional layer enhances the adhesion between layers in the light-control sheet 20.

The type of the light control film 20 is either a normal type or a reverse type. The normal type realizes high transmittance by applying a voltage between the first electrode layer 22M and the second electrode layer 23M. The normal type realizes low transmittance by stopping the application of voltage between the first electrode layer 22M and the second electrode layer 23M. In contrast, the reverse type realizes low transmittance by applying a voltage between the first electrode layer 22M and the second electrode layer 23M. The reverse type realizes high transmittance by stopping the application of voltage between the first electrode layer 22M and the second electrode layer 23M.

The end face of the first transparent coating substrate 11, the end face of the second transparent coating substrate 12, and the end face (outer surface) of the transparent adhesive layer 41 constitute the end face of the light-adjusting sheet 10. The end face of the light-adjusting sheet 10 is exposed to the outside of the light-adjusting sheet 10. The end face of the light-adjusting sheet 10 has a cut mark. The cut mark on the end face of the light-adjusting sheet 10 is a mark obtained by cutting the light-adjusting sheet 10 in the thickness direction, with the first transparent coating substrate 11, the second transparent coating substrate 12, and the transparent adhesive layer 41 as a single unit. One example of the cut mark is continuous with the end face of the first transparent coating substrate 11 and the outer surface of the transparent adhesive layer 41. One example of the cut mark on the transparent adhesive layer 41 is a streak extending in the circumferential direction of the light-adjusting sheet 10, the thickness direction of the light-adjusting sheet, or a direction intersecting these directions.

The end face of the light-adjusting sheet 10 is inclined with respect to the normal direction of the first bonding surface 11A and the normal direction of the second bonding surface 12A. The outer surface of the transparent adhesive layer 41 may intersect with the normal direction of the first bonding surface 11A or with the normal direction of the second bonding surface 12A. In the example shown in FIG. 3, the end face of the light-adjusting sheet 10 has a curved shape that is convex in the direction in which the light-adjusting film 20 spreads. The end face of the light-adjusting sheet 10 has a trapezoidal hypotenuse shape in a cross-sectional view of the light-adjusting sheet.

Since the outer surface of the transparent adhesive layer 41 has cut marks, it is possible to adjust the thickness of the transparent adhesive layer by cutting. For example, after the transparent adhesive is cured as the edge surface of the light control sheet, part of the cured product can be cut, thereby forming the transparent adhesive layer 41.

The end surface 20E of the light-adjusting film 20 includes the end surfaces of the support films 22T and 23T, the end surfaces 22E and 23E of the electrode layers 22M and 23M, and the end surface 21E of the liquid crystal layer 21. The transparent adhesive layer 41 is a cured product of a transparent adhesive that covers the entire end surface 20E. The water absorption rate of the transparent adhesive layer 41 is 2% or less. The water absorption rate of the transparent adhesive layer 41 is a value that conforms to JIS K 7209 (2000). From the viewpoint of being able to improve the waterproofing of the light-adjusting film 20, it is preferable that the first transparent coating substrate 11 and the second transparent coating substrate 12 are bonded to each other by the transparent adhesive layer 41 and cover the transparent adhesive layer 41.

The thickness 41T of the transparent adhesive layer 41 in the direction in which the light-adjusting film 20 spreads is preferably 1 mm or more from the viewpoint of improving the waterproofing of the light-adjusting film 20. If the thickness 41T of the transparent adhesive layer 41 is not constant in the thickness direction of the transparent adhesive layer 41, it is preferable that the minimum value of the thickness 41T of the transparent adhesive layer 41 is 1 mm or more.

The thickness 41T of the transparent adhesive layer 41 is preferably 5 mm or less from the viewpoint of improving the design when viewed from a position facing the light control film 20. When the thickness 41T of the transparent adhesive layer 41 is not constant in the thickness direction of the transparent adhesive layer 41, the maximum value of the thickness 41T of the transparent adhesive layer 41 is preferably 5 mm or less. For example, in the example shown in FIG. 3, the part showing the minimum value of the thickness 41T of the transparent adhesive layer 41 is in contact with the first transparent coated substrate 11 and preferably has a thickness of 1 mm or more. The part showing the maximum value of the thickness 41T of the transparent adhesive layer 41 is in contact with the first transparent coated substrate 11 and preferably has a thickness of 5 mm or less.

[Installation of light control sheet on glass]
A laminate (light-adjusting sheet) 10 formed by laminating (or pouching) a light-adjusting film 20 with a first transparent coated substrate 11 and a second transparent coated substrate 12 via a transparent adhesive layer 41 is applied to the surface of glass 30 of a building as shown in FIG. 1 to form a light-adjusting device 100.
In this case, a configuration in which one of the transparent coating substrates (here, the first transparent coating substrate 11) in the light-adjusting sheet 10 on the side that is bonded to the glass 30 surface and the transparent adhesive layer 41 are in a relationship that deviates from the appropriate thickness range is shown diagrammatically in Figure 4.

The appropriate thickness range for the transparent adhesive layer 41 is 50 to 100 μm, and the appropriate thickness range for the first transparent coated substrate 11 is 25 to 100 μm.

In the case shown in FIG. 1(a) where the thicknesses of the first transparent coating substrate 11 and the transparent adhesive layer 41 are all below the appropriate range, the transparent adhesive layer 41 cannot fully absorb the fine irregularities and wavy shapes that the support film of the light-control film 20 originally has, and the first transparent coating substrate 11 is also thin, resulting in a light-control sheet 10 with poor surface flatness due to a lack of reduction in distortion, resulting in significant damage to waterproofness and aesthetics.

In the same figure (b), which shows a case where the thickness of the transparent adhesive layer 41 is below the appropriate range and the thickness of the first transparent coating substrate 11 is above the appropriate range, the transparent adhesive layer 41 cannot fully absorb the fine irregularities and wavy shapes that the support film of the light-control film 20 originally has, but because the first transparent coating substrate 11 is excessively thick, distortion is reduced and a light-control sheet 10 is obtained that does not reduce surface flatness. On the other hand, this results in a decrease in the transparency of the light-control sheet 10, an increase in material costs, and a decrease in work efficiency when bonding it to the glass 30 surface.

In the case shown in FIG. 1C, where the thickness of the transparent adhesive layer 41 exceeds the appropriate range and the thickness of the first transparent coating substrate 11 falls below the appropriate range, the transparent adhesive layer 41 is able to fully absorb the fine irregularities and wavy shapes inherent in the support film of the light control film 20, and a light control sheet 10 is obtained in which distortion is reduced and surface flatness is not reduced. However, when used as a light control device bonded to the surface of glass 30, there are concerns about weather resistance (especially waterproofing), and long-term reliability is lacking.

In the case shown in FIG. 1D, in which the thicknesses of the first transparent coating substrate 11 and the transparent adhesive layer 41 are all above the appropriate range, the transparent adhesive layer 41 and the first transparent coating substrate 11 can fully absorb the fine irregularities and wavy shapes originally present in the support film of the light-controlling film 20, and a light-controlling sheet 10 is obtained in which distortion is reduced and surface flatness is not reduced. On the other hand, this leads to a decrease in the transparency of the light-controlling sheet 10, an increase in material costs, and a decrease in work efficiency when bonding to the glass 30 surface. In particular, this is undesirable because the light-controlling sheet 10 is less able to conform to the application surface to which it is applied, making it difficult to apply to surfaces with non-flat curved surfaces.

In the present invention, the "flatness" according to JIS B 0621 (1984) is adopted as an evaluation index for the deformation of the light-controlling sheet 10 due to bonding to the glass 30 surface. There are two types of flatness: the "maximum deflection type flatness" calculated from the maximum deviation of three planes that are set as far apart as possible on the target plane, and the "maximum inclination type flatness" calculated as the flatness of the gap value created when the target plane is sandwiched between parallel planes. The former is an index indicating the "warping value" and the latter is an index indicating the "warping shape". In the present invention, the pass criterion is that the latter gap value falls within the target value. The target value is set to within 120% (deformation amount within 20%) of the total thickness of the light-controlling sheet 10 (state in which the first transparent coating substrate 11, the second transparent coating substrate 12, the light-controlling film 20, the power line 31, and the transparent adhesive layer 41 are laminated and integrated).

Reference Signs List 10...light-adjusting sheet 11...first transparent coated substrate 11A...first bonding surface 12...second transparent coated substrate 12A...second bonding surface 20...light-adjusting film 20E...sheet end surface 21...liquid crystal layer 21P...spacer 22E, 23E...end surface 22M...first electrode layer 22T...first support film 23M...second electrode layer 23T...second support film 31...power line 41...transparent adhesive layer 100...light-adjusting device

Claims (3)

a first transparent-coated substrate having a first bonding surface;
a second transparent-coated substrate having a second bonding surface;
A light-controlling sheet comprising a light-controlling film located between the first joint surface and the second joint surface,
The light control film is
a first transparent electrode film including a first electrode layer and a first support film supporting the first electrode layer, the first support film being bonded to the first bonding surface;
a second transparent electrode film including a second electrode layer and a second support film supporting the second electrode layer, the second support film being bonded to the second bonding surface;
a liquid crystal layer including a liquid crystal composition filling a gap between the first transparent electrode film and the second transparent electrode film;
Further comprising a transparent adhesive layer that bonds the light control film to the first bonding surface and the light control film to the second bonding surface, the transparent adhesive layer having a thickness of 50 μm or more and 100 μm or less;
The end surface of the light-adjusting sheet has a cut mark extending from the end surface of the first transparent coated substrate to the end surface of the second transparent coated substrate in the thickness direction of the light-adjusting sheet and along the periphery of the first bonding surface ;
The first transparent-coated substrate and the second transparent-coated substrate have a thickness of 100 μm or less.
Dimming sheet. The transparent adhesive layer is a hot melt type adhesive layer.
The light controlling sheet according to claim 1. The light controlling sheet according to claim 1 or 2 ,
A light control device in the form of a post-attaching type, in which a first transparent coated substrate or a second transparent coated substrate is bonded onto a glass substrate via a transparent adhesive layer.