Dimming sheet

Abstract

To provide a dimmable sheet that can suppress the formation of air bubbles in the dimmable sheet. [Solution] In the dimmable sheet, the ratio of the mass of the liquid crystal mixture LCM to the mass of the dimmable layer 23 is 45% by mass or more and 65% by mass or less. The glass transition temperature Tg of each photopolymerizable compound homopolymer. k , and the mass ratio W of each photopolymerizable compound k The glass transition temperature Tg of the transparent polymer layer 23P is calculated using formula (1). ave However, it is 292K or higher.

Description

[Technical Field]

[0001] This disclosure relates to dimming sheets. [Background technology]

[0002] An example of a dimmable sheet comprises a first substrate, a second substrate, and a dimmable layer located between the first and second substrates. The first and second substrates are resin films with a transparent conductive film laminated on them. The dimmable layer is a polymer network liquid crystal (PNLC) or a polymer dispersed liquid crystal (PDLC). The edges of the dimmable layer are sealed with a sealant to prevent moisture from entering the dimmable layer (see, for example, Patent Document 1). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2024-115744 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] In dimmable sheets, the dimmable layer is sandwiched between two substrates, so gases contained within the dimmable layer during manufacturing are not easily released outside the sheet. As a result, the gas inside the dimmable sheet can condense, which can cause bubbles visible to the naked eye to form after the dimmable layer has been created. [Means for solving the problem]

[0005] A dimmable sheet for solving the above problems comprises: a first transparent conductive sheet including a first transparent electrode layer and a first transparent substrate supporting the first transparent electrode layer; a second transparent conductive sheet including a second transparent electrode layer and a second transparent substrate supporting the second transparent electrode layer; and a dimmable layer located between the first transparent electrode layer and the second transparent electrode layer. The dimmable sheet is configured to switch between a state in which the dimmable layer is transparent and a state in which it is opaque by switching between a state in which a voltage is applied between the first transparent electrode layer and the second transparent electrode layer and a state in which the voltage is not applied. The dimmable layer comprises a transparent polymer layer containing a plurality of polymers of one or more photopolymerizable compounds and defining a plurality of voids; a plurality of spacers dispersed in the transparent polymer layer; and a liquid crystal composition containing one or more liquid crystal compounds and located in the voids. The ratio of the mass of the one or more liquid crystal compounds to the mass of the dimmable layer is 45% by mass or more and 65% by mass or less. The glass transition temperature Tg of each photopolymerizable compound polymer k , and the mass ratio W of each photopolymerizable compound k The glass transition temperature Tg of the transparent polymer layer is calculated using the following formula (1). ave However, it is 292K or higher.

[0006]

number

[0007] According to the above dimming sheet, the glass transition temperature Tg of the transparent polymer layer ave Since the temperature is above 292K, the light-adjusting layer is less likely to soften even when the light-adjusting sheet is heated. Therefore, the movement of gas generated in the transparent polymer layer during the manufacturing of the light-adjusting sheet is suppressed when the light-adjusting sheet is heated, thereby suppressing gas aggregation. As a result, the formation of bubbles large enough to be visible to the naked eye on the light-adjusting sheet after the light-adjusting layer has formed is suppressed.

[0008] In the above-mentioned dimming sheet, the polymer of the photopolymerizable compound contains an atomic group located at the terminal of the polymer, and the atomic group is an atomic group generated from the photoradical polymerization initiator by the decomposition reaction of the photoradical polymerization initiator that occurs during the polymerization of the photopolymerizable compound. The transparent polymer layer may contain one or more atomic groups derived from at least one of the photoradical polymerization initiators represented by the following chemical formulas (1) to (4).

[0009]

Chem.

[0010] In Chemical Formula (1), R 1 is an arbitrary atomic group, and R 2 is a hydrocarbon group having 5 or more carbon atoms.

[0011]

Chem.

[0012] In Chemical Formula (2), R 3 is an arbitrary atomic group, R4 is a hydroxy group or an amino group, R 5 and R 6 are arbitrary atomic groups, and Chemical Formula (2) may have one or more bonds between the atomic group contained in R 5 and the atomic group contained in R 6 .

[0013]

Chem.

[0014] In Chemical Formula (3), R 7 , R 8 , and R 9 are each a phenyl group, and the hydrogen contained in each phenyl group may be substituted with another functional group.

[0015]

Chem.

[0016] In chemical formula (4), R 10 , R 11 , and, R 12 Each of these is a phenyl group, and the hydrogen atoms in each phenyl group may be substituted with other functional groups.

[0017] According to the above-described light-adjusting sheet, even if the photoradical polymerization initiator undergoes intramolecular cleavage, it is unlikely that compounds with molecular weights small enough to be gaseous at room temperature will be formed. Therefore, the formation of bubbles in the light-adjusting sheet is further suppressed.

[0018] In the above-described light-adjusting sheet, the polymer contained in the transparent polymer layer contains the atomic group derived from the photoradical polymerization initiator represented by the chemical formula (1), and the R in the photoradical polymerization initiator represented by the chemical formula (1) 2 It may be a phenyl group.

[0019] In the above-described light-adjusting sheet, the polymer contained in the transparent polymer layer is the photoradical polymerization initiator represented by the chemical formula (3), and R 7 and R 8 is a phenyl group, R 9 The atomic group derived from the photoradical polymerization initiator in which is a mesityl group, or the photoradical polymerization initiator represented by the chemical formula (4), wherein R 10 is a phenyl group, R 11 and R 12 The atomic group may also include the atomic group derived from the photoradical polymerization initiator, which has a mesityl group.

[0020] Each of the above-described dimming sheets can suppress the generation of gas within the dimming layer during the manufacturing of the dimming sheet, and can also enhance the contrast between the transparent state and the opaque state of the dimming sheet.

[0021] In the above-mentioned dimming sheet, after storing the dimming sheet for 100 days in an environment of 80°C and 85% relative humidity with the entire circumference of the end face of the dimming sheet sealed, the number of air bubbles in a plan view facing the first transparent conductive sheet is 1 bubble / 100cm². 2 It is acceptable to be less than [a certain value].

[0022] According to the above-mentioned dimming sheet, even if the dimming sheet is left undisturbed for a long period of time in a high-temperature and high-humidity environment, the formation of air bubbles in the dimming sheet is suppressed.

[0023] In the above-described dimming sheet, the liquid crystal composition may further contain a dichroic dye. According to the above-described dimming sheet, when the dimming sheet exhibits opacity, it also exhibits a color derived from the dichroic dye. Therefore, if the dimming sheet has air bubbles, the color difference between the air bubbles and the dimming layer tends to be more pronounced compared to when the liquid crystal composition does not contain dichroic dye. For this reason, the above-described dimming sheet allows for a more pronounced effect of reducing the likelihood of air bubbles forming in the dimming sheet. [Effects of the Invention]

[0024] According to the dimming sheet of this disclosure, the formation of air bubbles in the dimming sheet after the dimming layer has been formed is suppressed. [Brief explanation of the drawing]

[0025] [Figure 1] Figure 1 is a cross-sectional view showing the structure of a dimming device equipped with a normal type dimming sheet. [Figure 2] Figure 2 is a cross-sectional view showing the structure of a dimming device equipped with a reverse-type dimming sheet. [Figure 3] Figure 3 is a cross-sectional view showing the structure of the dimming layer in a normal type dimming sheet, along with a pair of transparent electrode layers. [Figure 4] Figure 4 is an explanatory diagram illustrating the reaction in an intramolecular cleavage-type photoradical polymerization initiator using a general formula. [Figure 5]Figure 5 is a schematic diagram illustrating the process by which bubbles form in the dimming layer. [Figure 6] Figure 6 is a schematic diagram illustrating the process by which bubbles form in the dimming layer. [Figure 7] Figure 7 is a schematic diagram illustrating the process by which bubbles form in the dimming layer. [Figure 8] Figure 8 is a schematic diagram illustrating the process by which bubbles form in the dimming layer. [Figure 9] Figure 9 is a table showing the mixing ratios and evaluation results for the coating solutions in Test Examples 1 to 7. [Figure 10] Figure 10 is a table showing the mixing ratios and evaluation results for the coating solutions in Test Examples 8 to 15. [Figure 11] Figure 11 is a table showing the mixing ratios and evaluation results for the coating solutions in Test Examples 16 to 20. [Figure 12] Figure 12 is an image of the dimming sheet of test example 18, taken from a viewpoint opposite the first transparent conductive sheet. [Figure 13] Figure 13 is a scatter plot showing the relationship between the contrast of the dimming sheet and the glass transition temperature (Tgave) of the transparent polymer layer. [Modes for carrying out the invention]

[0026] An embodiment of a dimmable sheet will be described with reference to Figures 1 to 13. The dimmable sheet in this disclosure may be of a normal type or a reverse type. Below, a normal type dimming device comprising a normal type dimmable sheet and a drive unit will be described with reference to Figure 1, and a reverse type dimming device comprising a reverse type dimmable sheet and a drive unit will be described with reference to Figure 2.

[0027] The dimming sheet can be attached to transparent components such as windows in moving objects like vehicles and aircraft. Alternatively, the dimming sheet may be attached to transparent components such as windows in various buildings like houses, train stations, and airports, partitions in offices, and display windows in shops. The dimming sheet may be flat or curved.

[0028] [Normal type dimmer] As shown in Figure 1, the normal type dimming device 10N comprises a normal type dimming sheet 11N and a drive unit 12. The dimming sheet 11N comprises a first transparent conductive sheet 21, a second transparent conductive sheet 22, and a dimming layer 23. The first transparent conductive sheet 21 includes a first transparent electrode layer 21A and a first transparent substrate 21B that supports the first transparent electrode layer 21A. The second transparent conductive sheet 22 includes a second transparent electrode layer 22A and a second transparent substrate 22B that supports the second transparent electrode layer 22A.

[0029] In the dimming sheet 11N, the dimming layer 23 is located between the first transparent electrode layer 21A and the second transparent electrode layer 22A. The first transparent electrode layer 21A is located between the first transparent substrate 21B and the dimming layer 23. The second transparent electrode layer 22A is located between the second transparent substrate 22B and the dimming layer 23.

[0030] The dimming sheet 11N is configured to allow switching between a state in which the dimming layer 23 is transparent and a state in which it is opaque by switching between a state in which a voltage is applied between the first transparent electrode layer 21A and the second transparent electrode layer 22A and a state in which no voltage is applied.

[0031] The dimming sheet 11N exhibits transparency and opacity with a higher haze value than transparency, depending on the magnitude of the voltage applied to the dimming layer 23. Since the dimming sheet 11N provided in the normal type dimming device 10N is of the normal type, the dimming sheet 11N exhibits opacity when no voltage is applied to the dimming layer 23. In contrast, the dimming sheet 11N exhibits transparency when voltage is applied to the dimming layer 23. For example, the haze value of the opaque dimming sheet 11N may be 80% or higher, and the haze value of the transparent dimming sheet 11N may be 5% or lower. The haze value of the dimming sheet 11N is a value measured by a method compliant with JIS K 7136:2000 "Plastics - Method for determining haze of transparent materials".

[0032] The dimming sheet 11N comprises a first electrode 21E attached to a portion of the first transparent electrode layer 21A and a second electrode 22E attached to a portion of the second transparent electrode layer 22A. The dimming sheet 11N further comprises a first wiring 24A connected to the first electrode 21E and a second wiring 24B connected to the second electrode 22E. The first electrode 21E is connected to the drive unit 12 by the first wiring 24A. The second electrode 22E is connected to the drive unit 12 by the second wiring 24B.

[0033] The first transparent conductive sheet 21 and the second transparent conductive sheet 22 apply a voltage to the dimming layer 23 that switches the dimming layer 23 between transparent and opaque. Each transparent conductive sheet 21 and 22 has light transmittance that allows visible light to pass through. The light transmittance of the first transparent conductive sheet 21 enables visual recognition of objects through the dimming sheet 11N. The light transmittance of the second transparent conductive sheet 22, similar to the light transmittance of the first transparent conductive sheet 21, enables visual recognition of objects through the dimming sheet 11N.

[0034] The material for forming each transparent electrode layer 21A, 22A may be any one selected from the group consisting of, for example, indium tin oxide, fluorine-doped tin oxide, tin oxide, zinc oxide, carbon nanotubes, poly(3,4-ethylenedioxythiophene), and silver.

[0035] The material forming each transparent substrate 21B, 22B may be a synthetic resin or an inorganic compound. Examples of synthetic resins include polyester, polyacrylate, polycarbonate, and polyolefin. Examples of polyester include polyethylene terephthalate and polyethylene naphthalate. Examples of polyacrylate include polymethyl methacrylate. Examples of inorganic compounds include silicon dioxide, silicon oxynitride, and silicon nitride.

[0036] Each electrode 21E, 22E is, for example, a flexible printed circuit (FPC). The FPC comprises a support layer, a conductor, and a protective layer. The conductor is sandwiched between the support layer and the protective layer. The support layer and the protective layer are formed of an insulating synthetic resin. The support layer and the protective layer are formed of, for example, polyimide. The conductor is formed of, for example, a thin metal film. The material forming the thin metal film may be, for example, copper. Each electrode 21E, 22E is not limited to an FPC, but may also be, for example, a metal tape.

[0037] Each electrode 21E and 22E is attached to each transparent electrode layer 21A and 22A by a conductive adhesive layer (not shown). In the portion of each electrode 21E and 22E connected to the conductive adhesive layer, the conductive portion is exposed from the protective or support layer.

[0038] The conductive adhesive layer may be formed from, for example, an anisotropic conductive film (ACF), anisotropic conductive paste (ACP), an isotropic conductive film (ICF), and an isotropic conductive paste (ICP). From the viewpoint of handling in the manufacturing process of the dimming device 10N, the conductive adhesive layer is preferably an anisotropic conductive film.

[0039] Each wiring 24A, 24B is formed, for example, by a metal wire and an insulating layer covering the metal wire. The wire is made of, for example, copper. The drive unit 12 is configured to apply a voltage to the dimming layer 23 of the dimming sheet 11N. The drive unit 12 applies an AC voltage between the first transparent electrode layer 21A and the second transparent electrode layer 22A. Preferably, the drive unit 12 applies an AC voltage having a rectangular wave shape between the pair of transparent electrode layers 21A and 22A. In other words, preferably, the drive unit 12 outputs a rectangular wave voltage signal.

[0040] [Reverse-type dimmer] The reverse-type dimming device 10R shown in Figure 2 differs from the normal-type dimming device 10N described above in that it is equipped with a reverse-type dimming sheet 11R. Therefore, the differences between the reverse-type dimming device 10R and the normal-type dimming device 10N will be explained in detail below. On the other hand, components in the reverse-type dimming device 10R that are common to the normal-type dimming device 10N will be given the same reference numerals as those in the normal-type dimming device 10N, and a detailed explanation of those components will be omitted.

[0041] As shown in Figure 2, the reverse-type dimming device 10R comprises a reverse-type dimming sheet 11R and a drive unit 12. In addition to the layer structure of the normal-type dimming sheet 11N, the dimming sheet 11R includes a first alignment film 21C and a second alignment film 22C. In the reverse-type dimming device 10R, the first transparent conductive sheet 21 includes a first transparent electrode layer 21A and a first transparent substrate 21B, in addition to the first alignment film 21C. The second transparent conductive sheet 22 includes a second transparent electrode layer 22A and a second transparent substrate 22B, in addition to the second alignment film 22C.

[0042] The photochromic layer 23 is located between the first alignment layer 21C and the second alignment layer 22C. The first alignment layer 21C is located between the photochromic layer 23 and the first transparent electrode layer 21A and is in contact with the photochromic layer 23. The second alignment layer 22C is located between the photochromic layer 23 and the second transparent electrode layer 22A and is in contact with the photochromic layer 23.

[0043] The material for forming the first alignment film 21C and the second alignment film 22C may be an organic compound, an inorganic compound, or a mixture thereof. Examples of organic compounds include polyimide, polyamide, polyvinyl alcohol, and cyanide compounds. Examples of inorganic compounds include silicon oxide and zirconium oxide. The material for forming the alignment films 21C and 22C may also be silicone. Silicone is a compound having an inorganic portion and an organic portion.

[0044] The first alignment film 21C and the second alignment film 22C are, for example, vertical alignment films. The vertical alignment films orient the long axis of the liquid crystal compound so that it is perpendicular to the surface opposite to the surface in contact with the first transparent electrode layer 21A and the surface opposite to the surface in contact with the second transparent electrode layer 22A. In this way, the alignment films 21C and 22C regulate the orientation of the multiple liquid crystal compounds contained in the light-adjusting layer 23.

[0045] The dimming sheet 11R exhibits transparency and opacity with a higher haze value than transparency, depending on the magnitude of the voltage applied to the dimming layer 23. Since the dimming sheet 11R provided in the reverse-type dimming device 10R is of the reverse type, the dimming sheet 11R exhibits transparency when no voltage is applied to the dimming layer 23. In contrast, the dimming sheet 11R exhibits opacity when voltage is applied to the dimming layer 23. For example, the haze value of the opaque dimming sheet 11R may be 80% or higher, and the haze value of the transparent dimming sheet 11R may be 5% or lower.

[0046] In both dimming sheets 11N and 11R, after storing them for 100 days in an environment of 80°C and 85% relative humidity with the entire circumference of the end face sealed, the number of air bubbles in a plan view facing the first transparent conductive sheet 21 was 1 bubble / 100cm². 2It is less than [value missing]. The end faces of the dimming sheets 11N and 11R include an annular surface connecting the front and back surfaces of the transparent conductive sheets 21 and 22, and an annular surface connecting the front and back surfaces of the dimming layer 23. With the dimming sheets 11N and 11R, even if the dimming sheets 11N and 11R are left undisturbed for a long period of time in a high-temperature and high-humidity environment, the formation of air bubbles in the dimming sheets 11N and 11R is suppressed.

[0047] [Light-regulating layer] Figure 3 shows the cross-sectional structure of the dimming layer 23 of the normal type dimming sheet 11N. The reverse type dimming sheet 11R has the same layer structure as shown in Figure 3, except that it includes a first alignment layer 21C and a second alignment layer 22C.

[0048] As shown in Figure 3, the light-adjusting layer 23 includes a transparent polymer layer 23P, a plurality of spacers SP, and a liquid crystal composition 23LC. The transparent polymer layer 23P contains a plurality of polymers composed of one or more photopolymerizable compounds and defines a plurality of voids 23D. The plurality of spacers SP are dispersed in the transparent polymer layer 23P. The liquid crystal composition 23LC contains one or more liquid crystal compounds and is located in the voids 23D. In this embodiment, the liquid crystal composition 23LC includes a liquid crystal mixture LCM which is a mixture of two or more liquid crystal compounds. The liquid crystal composition 23LC may contain only one liquid crystal compound. The light-adjusting layer 23 of this embodiment satisfies conditions 1 and 2 described below.

[0049] [Liquid crystal composition] As described above, the liquid crystal composition 23LC contains a liquid crystal mixture LCM. The content ratio of the liquid crystal mixture LCM to the mass of the light-adjusting layer 23 is 45% by mass or more and 65% by mass or less. That is, the mass M23 of the light-adjusting layer 23 and the mass MLCM of the liquid crystal mixture LCM satisfy the following formula. Note that the mass M23 of the light-adjusting layer 23 is the sum of the mass MLCM of the liquid crystal mixture LCM, the mass M23P of the transparent polymer layer 23P, and the mass MSP of the spacer SP. Also, the mass M23P of the transparent polymer layer 23P is the sum of the mass of the photopolymerizable composition and the mass of the polymerization initiator. The mass M23 of the light-adjusting layer 23 and the mass M23P of the transparent polymer layer 23P may each include the mass of the chain transfer agent. Also, the mass M23 of the light-adjusting layer 23 may include the mass of the dichroic dye.

[0050] (Condition 1) 45 (mass%)≦(MLCM / M23)×100≦65 (mass%) Since the upper limit of the liquid crystal mixture (LCM) content is 65% by mass, the transparent polymer layer 23P contained in the light-adjusting layer 23 makes it possible to maintain high adhesion strength between the light-adjusting layer 23 and each transparent conductive sheet 21, 22. This suppresses the peeling of the light-adjusting layer 23 from the transparent conductive sheets 21, 22. Since the lower limit of the liquid crystal mixture (LCM) content is 45% by mass, light is easily scattered within the light-adjusting sheets 11N, 11R to the extent that they have high contrast. The contrast of the light-adjusting sheets 11N, 11R is the ratio of the total light transmittance value when the light-adjusting sheets 11N, 11R are transparent to the total light transmittance value when the light-adjusting sheets 11N, 11R are opaque. In this way, by keeping the liquid crystal mixture (LCM) content within the range of 45% by mass to 65% by mass, it is possible to achieve both high optical properties and high mechanical properties in the light-adjusting sheets 11N, 11R.

[0051] The liquid crystal composition 23LC may contain a dichroic dye and may also contain additives such as an antifoaming agent, antioxidant, weathering agent, solvent, and viscosity reducer. The weathering agent may be an ultraviolet absorber or a light stabilizer.

[0052] The liquid crystal mixture LCM may have positive dielectric anisotropy. When the liquid crystal mixture LCM has positive dielectric anisotropy, the dielectric constant ε∥ in the long axis direction of the liquid crystal mixture LCM is higher than the dielectric constant ε⊥ in the short axis direction of the liquid crystal mixture LCM. The liquid crystal mixture LCM may have negative dielectric anisotropy. When the liquid crystal mixture LCM has negative dielectric anisotropy, the dielectric constant ε∥ in the long axis direction of the liquid crystal mixture LCM is lower than the dielectric constant ε⊥ in the short axis direction of the liquid crystal mixture LCM. The dielectric anisotropy of the liquid crystal mixture LCM is appropriately selected based on the type of dimming sheet 11N, 11R. The normal type dimming sheet 11N may, for example, include a liquid crystal mixture LCM having positive dielectric anisotropy. The reverse type dimming sheet 11R may, for example, include a liquid crystal mixture LCM having negative dielectric anisotropy.

[0053] Each liquid crystal compound contained in the liquid crystal mixture LCM is selected from the group consisting of, for example, Schiff bases, azos, azoxys, biphenyls, terphenyls, benzoic acid esters, trans, pyrimidines, pyridazines, cyclohexanecarboxylic acid esters, phenylcyclohexanes, biphenylcyclohexanes, dicyanobenzenes, naphthalenes, and dioxanes. The liquid crystal mixture LCM is a combination of two or more liquid crystal compounds. The refractive index difference of the liquid crystal mixture LCM may be 0.05 or greater. The dielectric constant difference of the liquid crystal compounds contained in the liquid crystal mixture LCM may be 2 or greater, or -2 or less.

[0054] An example of a liquid crystal compound structure is represented by the following chemical formula (5).

[0055] [ka]

[0056] The R shown in chemical formula (5) 21 R is a hydrogen atom or an alkyl group having 1 to 20 carbon atoms. 21One or more non-adjacent methylene bonds in the alkyl group can be substituted with any of the following selected from the group consisting of an oxygen atom, an ethylene bond, an ester bond, or a diether bond.

[0057] The R shown in chemical formula (5) 22 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. 22 One or more non-adjacent methylene bonds in the alkyl group can be substituted with any of the following: an oxygen atom, an ethylene bond, an ester bond, or a diether bond.

[0058] Chemical formula (5) shows A 21 , A 22 , A 23 , A 24 These are, independently, a 1,4-phenylene group and a 2,6-naphthylene group. One or more hydrogen atoms in the 1,4-phenylene group and the 2,6-naphthylene group can be substituted with a fluorine atom, a chlorine atom, a trifluoromethyl group, or a trifluoromethoxy group. A shown in chemical formula (5) 21 , A 22 , A 23 , A 24 These may each be independently a 1,4-cyclohexylene group, a 3,6-cyclohexenylene group, a 1,3-dioxan-2,5-diyl group, or a pyridine-2,5-diyl group. A shown in chemical formula (5) 23 , A 24 Each of these can be a single bond independently. The Z shown in chemical formula (5) 21 , Z 22 , Z 23 Each of these is independently selected from the group consisting of single bonds, ester bonds, diether bonds, ethylene bonds, fluoroethylene bonds, and carbonyl bonds.

[0059] [Transparent polymer layer] The transparent polymer layer 23P is a cured product of a photopolymerizable compound. The transparent polymer layer 23P contains multiple polymers formed by the polymerization of one or more photopolymerizable compounds. That is, the polymers constituting the transparent polymer layer 23P may consist only of homopolymers, only of copolymers, or a combination of homopolymers and copolymers. If the transparent polymer layer 23P contains homopolymers, it may contain only one type of homopolymer or two or more types of homopolymers. If the transparent polymer layer 23P contains copolymers, it may contain only one type of copolymer or two or more types of copolymers. The copolymer is composed of two or more photopolymerizable compounds.

[0060] The light used to polymerize the photopolymerizable compound may be ultraviolet light or an electron beam. The photopolymerizable compound may be an ultraviolet polymerizable compound or an electron beam polymerizable compound. The lower and upper limits of the content of the transparent polymer layer 23P in the light-adjusting layer 23 are within the range in which liquid crystal particles composed of the liquid crystal mixture LCM undergo phase separation from the polymer of the photopolymerizable compound during the polymerization process of the photopolymerizable compound. If it is necessary to increase the mechanical strength of the transparent polymer layer 23P, a higher lower limit of the content of the transparent polymer layer 23P is preferable. If it is necessary to lower the voltage for driving the liquid crystal mixture LCM, a lower upper limit of the content of the transparent polymer layer 23P is preferable.

[0061] The transparent polymer layer 23P satisfies condition 2 below. (Condition 2) Glass transition temperature Tg of each photopolymerizable compound in homopolymers k , and the mass ratio W of each photopolymerizable compound k The glass transition temperature Tg of the transparent polymer layer 23P is calculated using the following formula (1). ave However, it is above 292K. Mass ratio W of each photopolymerizable compound k This is the ratio of the mass of a photopolymerizable compound to the total mass of that photopolymerizable compound.

[0062]

number

[0063] According to the dimming sheet disclosed herein, the glass transition temperature Tg of the transparent polymer layer 23P ave Since the temperature is above 292K, the light-adjusting layer 23 does not easily soften even when the light-adjusting sheets 11N and 11R are heated. Therefore, the movement of gas generated in the transparent polymer layer 23P during the manufacturing of the light-adjusting sheets 11N and 11R is suppressed when the light-adjusting sheets 11N and 11R are heated, thereby suppressing gas aggregation. As a result, the formation of bubbles large enough to be visible to the naked eye on the light-adjusting sheets 11N and 11R after the formation of the light-adjusting layer 23 is suppressed.

[0064] Bubbles large enough to be visible to the naked eye are those with a maximum diameter of 1 mm or more. When viewed from a viewpoint opposite the first transparent conductive sheet 21, if the bubble is circular, the diameter of bubble AB is the maximum diameter; if the bubble is elliptical, the major axis of the bubble is the maximum diameter. If the bubble has an irregular shape, the diameter of the circle circumscribing the bubble is the maximum diameter.

[0065] From the perspective of enhancing the contrast of the dimming sheets 11N and 11R, the glass transition temperature Tg of the transparent polymer layer 23P is important. ave The glass transition temperature Tg of the transparent polymer layer 23P is preferably 315K or less, and more preferably 310K or less. ave Because the temperature is 315K or lower, the driving of the liquid crystal mixture (LCM) is less likely to be hindered by the transparent polymer layer 23P.

[0066] A polymer of a photopolymerizable compound may contain atomic groups located at the ends of the polymer. These atomic groups are generated from the photoradical polymerization initiator by intramolecular cleavage of the photoradical polymerization initiator that occurs during the polymerization of the photopolymerizable compound.

[0067] The transparent polymer layer 23P may also satisfy condition 3 below. In addition, in the case of the light-adjusting sheets 11N and 11R, if condition 1 above and condition 3 below are satisfied, even if condition 2 above is not satisfied, the formation of bubbles large enough to be visible to the naked eye on the light-adjusting sheets 11N and 11R after the formation of the light-adjusting layer 23 will be suppressed.

[0068] (Condition 3) The transparent polymer layer 23P contains one or more atomic groups derived from at least one photoradical polymerization initiator represented by the following chemical formulas (1) to (4).

[0069] [ka]

[0070] In chemical formula (1), R 1 R is any atomic group, 2 It is a hydrocarbon group having 5 or more carbon atoms.

[0071] [ka]

[0072] In chemical formula (2), R 3 R is any atomic group, 4 R is a hydroxyl group or an amino group, 5 and R 6 R is an arbitrary group of atoms, and chemical formula (2) is R 5 The atomic group and R that it contains 6 It may have one or more bonds with the atomic group it contains.

[0073] [ka]

[0074] In chemical formula (3), R 7 , R 8 , and, R 9Each of these is a phenyl group, and the hydrogen atoms in each phenyl group may be substituted with other functional groups.

[0075] [ka]

[0076] In chemical formula (4), R 10 , R 11 , and, R 12 Each of these is a phenyl group, and the hydrogen atoms in each phenyl group may be substituted with other functional groups.

[0077] When the transparent polymer layer 23P satisfies condition 3, even if the photoradical polymerization initiator undergoes intramolecular cleavage, compounds with molecular weights small enough to be gaseous at room temperature are less likely to be formed. Therefore, the formation of bubbles in the light-adjusting sheets 11N and 11R is further suppressed. In this disclosure, room temperature refers to the standard temperature of 298.15 K at a standard pressure of 100 kPa.

[0078] Figure 4 shows the reaction equation for the initiation of radical polymerization when an intramolecular cleavage type photoradical polymerization initiator is used. For the sake of explanation, in Figure 4, the photoradical polymerization initiator corresponds to chemical formula (1), and R 2 This is shown in the general formula where is a methyl group.

[0079] As shown in Figure 4, when light is irradiated onto the photoradical polymerization initiator PI, the photoradical polymerization initiator PI is cleaved, generating a first radical PIA and a second radical PIB. Next, the second radical PIB is further cleaved, generating carbon dioxide (CO2) and a methyl radical PIC. Subsequently, electrons and hydrogen atoms are exchanged between the methyl radical PIC and the polymer PL, generating methane (CH4). Since methane is a gas under standard conditions, the polymerization reaction of the photopolymerizable compound generates gas within the light-adjusting layer 23.

[0080] Although carbon dioxide is a gas under standard conditions, it will not form bubbles in the dimming sheets 11N and 11R unless it is present in a volume several times that of methane. For example, if 3% by mass or more of a photoradical polymerization initiator PI that produces carbon dioxide through intramolecular cleavage is added, the function of the dimming sheets 11N and 11R themselves will be impaired.

[0081] When the photoradical polymerization initiator PI satisfies condition 3, the generation of methane in the above-described reaction equation is suppressed. As a result, the light-adjusting layer 23 formed through the polymerization reaction of the photopolymerizable compound is less likely to contain gas. Consequently, the formation of air bubbles in the light-adjusting sheets 11N and 11R after the formation of the light-adjusting layer 23 is suppressed.

[0082] The transparent polymer layer 23P may satisfy at least one of the following conditions 4 to 6. That is, the transparent polymer layer 23P may satisfy only one of conditions 4 to 6, or it may satisfy two or more of conditions 4 to 6.

[0083] (Condition 4) The polymer contained in the transparent polymer layer 23P contains an atomic group derived from the photoradical polymerization initiator represented by chemical formula (1), and the R in the photoradical polymerization initiator represented by chemical formula (1) 2 This is a phenyl group.

[0084] (Condition 5) The polymer contained in the transparent polymer layer 23P is a photoradical polymerization initiator represented by chemical formula (3), and R 7 and R 8 is a phenyl group, R 9 It contains an atomic group derived from a photoradical polymerization initiator whose component is a mesityl group.

[0085] (Condition 6) The polymer contained in the transparent polymer layer 23P is a photoradical polymerization initiator represented by chemical formula (4), and R 10 is a phenyl group, R 11 and R 12 It contains an atomic group derived from a photoradical polymerization initiator whose component is a mesityl group.

[0086] If the transparent polymer layer 23P satisfies at least one of conditions 4 to 6, it is possible to suppress the generation of gas within the light-adjusting layer 23 during the manufacturing of the light-adjusting sheets 11N and 11R, and to enhance the contrast between the transparent state and the opaque state of the light-adjusting sheets 11N and 11R.

[0087] The photoradical polymerization initiator may be an intramolecular cleavage type photoradical polymerization initiator or a hydrogen abstraction type photoradical polymerization initiator. Examples of intramolecular cleavage-type photoradical polymerization initiators may be 1-hydroxycyclohexylphenyl ketone, 1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxymethylpropanone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2-dimethylamino-2-(4-methylbenzyl)-1-(4-morpholine-4-ylphenyl)-butan-1-one, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, 1,2-octanedione, 1-[4-(phenylthio)phenyl]-,2-(o-benzoyl oxime), ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]-,1-(o-acetyl oxime).

[0088] The UV-curable compound may be at least one selected from the group consisting of acrylate compounds, methacrylate compounds, styrene compounds, thiol compounds, and oligomers of each compound.

[0089] Acrylate compounds include monoacrylate compounds, diacrylate compounds, triacrylate compounds, and tetraacrylate compounds. Examples of acrylate compounds include butyl ethyl acrylate, ethylhexyl acrylate, cyclohexyl acrylate, n-butyl acrylate, isobolonyl acrylate, methoxytriethylene glycol acrylate, dipropylene glycol diacrylate, and pentaerythritol tetraacrylate. Examples of methacrylate compounds include dimethacrylate compounds, trimethacrylate compounds, and tetramethacrylate compounds. Examples of methacrylate compounds include N,N-dimethylaminoethyl methacrylate, phenoxyethyl methacrylate, methoxyethyl methacrylate, and tetrahydrofurfuryl methacrylate. Examples of thiol compounds include 1,3-propanedithiol and 1,6-hexanedithiol. Examples of styrene compounds include styrene and methylstyrene.

[0090] [Spacer] The spacer SP is dispersed throughout the transparent polymer layer 23P. The thickness of the spacer SP determines the thickness of the light-adjusting layer 23. The thickness of the spacer SP may also be determined by the particle size of the spacer SP. The thickness of the light-adjusting layer 23 may be, for example, 5 μm or more and 100 μm or less. The spacer SP makes the thickness of the light-adjusting layer 23 uniform. The spacer SP may be a bead spacer or a photospacer formed by exposure and development of a photoresist. The spacer SP may be colorless and transparent or colored and transparent. If the liquid crystal composition 23LC contains a dichroic dye DP, it is preferable that the color of the spacer SP is the same as the color exhibited by the dichroic dye DP.

[0091] [Dichroic pigments] As described above, the liquid crystal composition 23LC may contain a dichroic dye. The dichroic dye exhibits color when driven by a guest-host type with the liquid crystal mixture LCM as the host. The dichroic dye is, for example, 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 may be a single compound or a combination of two or more compounds. When it is required to improve lightfastness and increase the dichroic ratio, the dichroic dye is preferably at least one selected from the group consisting of azo compounds and anthraquinone compounds, and more preferably an azo compound.

[0092] When the liquid crystal composition 23LC contains a dichroic dye, the light-adjusting sheets 11N and 11R exhibit a color derived from the dichroic dye when they become opaque. Therefore, if the light-adjusting sheets 11N and 11R have air bubbles, the color difference between the air bubbles and the light-adjusting layer 23 tends to be more pronounced compared to when the liquid crystal composition 23LC does not contain a dichroic dye. Consequently, the effect of being less prone to air bubble formation can be more significantly obtained with the light-adjusting sheets 11N and 11R.

[0093] [Manufacturing method for dimmable sheets] The method for manufacturing the dimmable sheet 11N includes forming a coating film containing the above-mentioned photopolymerizable compound and liquid crystal mixture LCM between a first transparent conductive sheet 21 and a second transparent conductive sheet 22. When manufacturing a normal type dimmable sheet 11N, a coating film is formed between the first transparent electrode layer 21A of the first transparent conductive sheet 21 and the second transparent electrode layer 22A of the second transparent conductive sheet 22. In contrast, when manufacturing a reverse type dimmable sheet 11R, a coating film is formed between the first alignment layer 21C of the first transparent conductive sheet 21 and the second alignment layer 22C of the second transparent conductive sheet 22.

[0094] The coating film contains a photoradical polymerization initiator for initiating the polymerization of the photopolymerizable compound. The photoradical polymerization initiator may be at least one of the compounds described above. The manufacturing method for the dimmable sheets 11N and 11R includes separating liquid crystal particles composed of a liquid crystal mixture (LCM) from the polymer by polymerizing a photopolymerizable compound within the coating film. The light irradiated onto the coating film may be directed towards the first transparent conductive sheet 21, towards the second transparent conductive sheet 22, or towards both the first transparent conductive sheet 21 and the second transparent conductive sheet 22.

[0095] Phase separation of liquid crystal particles composed of a liquid crystal mixture (LCM) proceeds through polymerization of a photopolymerizable compound and diffusion of the LCM. The polymerization rate of the photopolymerizable compound depends on the intensity of the light irradiated onto the photopolymerizable compound. The diffusion rate of the LCM depends on the processing temperature during polymerization of the photopolymerizable compound. In the phase separation of the LCM, the intensity of the light irradiated onto the photopolymerizable compound is set so that the size of the liquid crystal particles becomes a desired size, i.e., so that the size of the voids 23D becomes a desired size. In addition, heating may be performed during the phase separation of the LCM to promote diffusion of the LCM.

[0096] When it is required to reduce the size of the void 23D, it is preferable to increase the intensity of the light irradiated onto the photopolymerizable compound and to proceed with polymerization at a low temperature to suppress the diffusion of the liquid crystal mixture LCM. When it is required to increase the size of the void 23D, it is preferable to decrease the intensity of the light irradiated onto the photopolymerizable compound and to proceed with polymerization at a high temperature to promote the diffusion of the liquid crystal mixture LCM.

[0097] Referring to Figures 5 to 8, the process of bubble formation in the dimming sheets 11N and 11R will be explained. In the following, the process of bubble formation in the normal type dimming sheet 11N will be explained. The reverse type dimming sheet 11R differs from the normal type dimming sheet 11N in that it has a pair of alignment films 21C and 22C sandwiching the dimming layer 23, but the mechanism of bubble formation in the dimming sheet 11R is the same as that of the dimming sheet 11N. Therefore, the explanation of the process of bubble formation in the dimming sheet 11R will be omitted.

[0098] As shown in Figure 5, when light L is irradiated onto the coating film CF sandwiched between the first transparent electrode layer 21A and the second transparent electrode layer 22A, polymer 23PP begins to be generated from the photopolymerizable compound within the coating film CF. As a result, voids 23D also begin to form within the coating film CF. At this time, if the photoradical polymerization initiator contained in the coating film CF is an intramolecular cleavage type photoradical polymerization initiator, and low molecular weight molecules are generated by the intramolecular cleavage of the photoradical polymerization initiator, then many small bubbles of gas G are formed within the coating film CF.

[0099] As shown in Figure 6, continued irradiation of the coating film CF with light forms a transparent polymer layer 23P that defines a plurality of voids 23D of a predetermined size. A liquid crystal composition 23LC containing a liquid crystal mixture LCM is located within the voids 23D. Small bubbles of gas G generated during the formation of the transparent polymer layer 23P are located within the light-adjusting layer 23, which contains the transparent polymer layer 23P and the liquid crystal composition 23LC. These small bubbles of gas G are present both within the transparent polymer layer 23P and within the liquid crystal composition 23LC. At the time the light-adjusting layer 23 is formed, the size of the bubbles is too small to be seen with the naked eye. In other words, the bubbles are smaller than the resolution of a human eye.

[0100] As shown in Figure 7, when heat H is applied to the light-adjusting sheet 11N after the light-adjusting layer 23 has been formed, the transparent polymer layer 23P softens or the internal stress of the transparent polymer layer 23P is relieved. As a result, the gas G inside the light-adjusting layer 23 is released to the outside of the light-adjusting layer 23. Alternatively, if an external force is applied to the light-adjusting layer 23 at the same time as heat H is applied to the light-adjusting layer 23, internal stress accumulates inside the light-adjusting layer 23. Therefore, the gas G inside the light-adjusting layer 23 moves towards the space between the first transparent electrode layer 21A and the light-adjusting layer 23 where the transparent polymer layer 23P is not present, or between the second transparent electrode layer 22A and the light-adjusting layer 23.

[0101] The process of heating the dimming sheets 11N and 11R after the dimming layer 23 has been formed is, for example, a heat-pressure bonding process for the production of laminated glass. In this process, the dimming sheets 11N and 11R are heated to a temperature of 100°C to 150°C.

[0102] As shown in Figure 8, the gas G released from within the light-adjusting layer 23 aggregates between the light-adjusting layer 23 and the first transparent electrode layer 21A, or between the light-adjusting layer 23 and the second transparent electrode layer 22A. As a result, bubbles AB large enough to be visible to the naked eye are formed in at least one of the spaces between the light-adjusting layer 23 and the first transparent electrode layer 21A, and between the light-adjusting layer 23 and the second transparent electrode layer 22A.

[0103] In this regard, in the dimming sheets 11N and 11R of this disclosure, the glass transition temperature Tg of the transparent polymer layer 23P included in the dimming layer 23 ave Since the temperature is above 292K, softening of the transparent polymer layer 23P is less likely to occur, and stress relaxation is also less likely to occur. As a result, in the light-adjusting layer 23, the position of gas G does not change easily before and after heating of the light-adjusting layer 23, and as a result, the formation of condensed gas bubbles AB is less likely to occur.

[0104] [Example Test] The test examples will be explained with reference to Figures 9 to 13. Note that the type of dimmable sheet 11N in each of the test examples described below is the normal type. A coating film containing a photopolymerizable compound and a liquid crystal mixture (LCM) was formed between the first transparent conductive sheet 21 and the second transparent conductive sheet 22. Subsequently, the photopolymerizable compound was polymerized within the coating film to obtain the dimmable sheet 11N.

[0105] The following materials were used to form the dimmable sheet 11N of the test examples. In each dimmable sheet 11N of the test examples, the mixing ratio in the coating solution for forming the coating film was set as shown in Figures 9 to 11. The mixing ratios shown in Figures 9 to 11 represent the proportion of each material to the total amount of the coating solution. That is, the mixing ratio represents the proportion of each material to the sum of the mass of the liquid crystal mixture LCM, the mass of the photopolymerizable compound, the mass of the spacer SP, the mass of the photoradical polymerization initiator PI, the mass of the chain transfer agent CTA, and the mass of the dichroic dye DP.

[0106] [material] • First transparent electrode layer 21A: Indium tin oxide • Second transparent electrode layer 22A: Indium tin oxide • First transparent substrate 21B: Polyethylene terephthalate film • Second transparent substrate 22B: Polyethylene terephthalate film • Liquid crystal mixture LCM: Cyanobiphenyl liquid crystal (MLC-6609, manufactured by Merck) • Chain transfer agent CTA: Pentaerythritol tetrakis(3-mercaptobutyrate) (Kalenz MT PE1, manufactured by Resonac Co., Ltd.) (Kalenz is a registered trademark) • Dichroic dye DP: Dichroic dye for liquid crystals (YH-428, manufactured by Mitsui Chemicals Fine Co., Ltd.) • Spacer SP: Perfectly spherical with a diameter of 20 μm (biphenyl copolymer) (Micropearl SP-220, manufactured by Sekisui Chemical Co., Ltd.) (Micropearl is a registered trademark)

[0107] ·Ultraviolet polymerizable compounds Component MN1: n-butyl acrylate (glass transition temperature 218.15K) (chemical formula (6)) Component MN2: Isobolonyl acrylate (glass transition temperature 370.15K) (Chemical formula (7)) Component MN3: Methoxytriethylene glycol acrylate (glass transition temperature 223.15K) (Light Acrylate MTG-A, Kyoeisha Chemical Co., Ltd.) (Light Acrylate is a registered trademark) (Chemical formula (8)) Component MN4: Dipropylene glycol diacrylate (glass transition temperature 383.15K) (APG-100, manufactured by Shin-Nakamura Chemical Co., Ltd.) (Chemical formula (9)) Component MN5: Pentaerythritol tetraacrylate (glass transition temperature 376.15K) (A-TMMT, manufactured by Shin-Nakamura Chemical Co., Ltd.) (Chemical formula (10))

[0108] [ka]

[0109] [ka]

[0110] [ka]

[0111] [ka]

[0112] [ka]

[0113] • Initiator of photoradical polymerization Component PI1: 1-Hydroxycyclohexylphenyl ketone (Omnirad 184, manufactured by IGM) (Omnirad is a registered trademark) (Chemical formula (11)) Component PI2: 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxymethylpropanone (Omnirad 2959, manufactured by IGM) (Chemical formula (12)) Component PI3: 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one (Omnirad 907, manufactured by IGM) (Chemical formula (13)) Component PI4: 2-dimethylamino-2-(4-methylbenzyl)-1-(4-morpholine-4-ylphenyl)-butan-1-one (Omnirad 379, manufactured by IGM) (Chemical formula (14)) Component PI5: 2,4,6-trimethylbenzoyldiphenylphosphine oxide (Omnirad TPO, manufactured by IGM) (Chemical formula (15)) Component PI6: Bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (Omnirad 380, manufactured by IGM) (Chemical formula (16)) Component PI7: 1,2-octanedione, 1-[4-(phenylthio)phenyl]-,2-(o-benzoyloxime) (Irgacure OXE01, manufactured by BASF) (Irgacure is a registered trademark) (Chemical formula (17)) Ingredient PI8: Ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]-, 1-(O-acetyloxime) (Irgacure OXE02, manufactured by BASF) (Chemical formula (18))

[0114] Of the components PI1 to PI8, component PI7 corresponds to chemical formula (1), components PI2 to PI1 to PI4 correspond to chemical formula (2), component PI5 corresponds to chemical formula (3), and component PI6 corresponds to chemical formula (4).

[0115] [ka]

[0116] [ka]

[0117] [ka]

[0118] [ka]

[0119] [ka]

[0120] [ka]

[0121] [ka]

[0122] [ka]

[0123] [Test Example 1] As shown in Figure 9, a coating solution was prepared by mixing a liquid crystal mixture LCM, a photopolymerizable compound, a chain transfer agent CTA, a dichroic dye DP, a photoradical polymerization initiator component PI1, and a spacer SP in the following proportions. The glass transition temperature Tg of the transparent polymer layer 23P is also shown. ave The value was 259.2K.

[0124] Liquid crystal mixture LCM: 49.5% by mass Ingredient MN1: 24.1% by mass Component MN2: 10.7% by mass Component MN3: 4.8% by mass Component MN4: 2.5% by mass Ingredient MN5: 4.4% by mass Chain transfer agent CTA: 2.0% by mass Dichroic dye DP: 0% by mass Ingredient PI1: 1.0% by mass

[0125] A coating film with a thickness of 20 μm was formed on the first transparent electrode layer 21A using a coating solution, and then 1.0 mass% of spacer SP was scattered into the coating film. With the coating film containing the spacer SP sandwiched between the first transparent electrode layer 21A and the second transparent electrode layer 22A, ultraviolet light with a wavelength of 365 nm was irradiated toward both the first transparent substrate 21B and the second transparent substrate 22B. This obtained the light-adjusting sheet 11N of Test Example 1. At this time, the intensity of the ultraviolet light was set to 10 mW / cm² in each transparent substrate 21B and 22B. 2 I set it to [a certain setting] and also set the UV irradiation time to 100 seconds.

[0126] [Test Example 2] As shown in Figure 9, the light-adjusting sheet 11N of Test Example 2 was obtained by the same method as in Test Example 1, except that the mixing ratio of the photopolymerizable compound, the chain transfer agent CTA, and the dichroic dye DP was changed as follows. Glass transition temperature Tg of transparent polymer layer 23P ave The value was 259.2K.

[0127] Ingredient MN1: 22.2% by mass Component MN2: 9.8% by mass Component MN3: 4.5% by mass Component MN4: 2.2% by mass Ingredient MN5: 4.0% by mass Chain transfer agent CTA: 1.8% by mass Dichroic dye DP: 4.0% by mass

[0128] [Test Example 3] As shown in Figure 9, the light-adjusting sheet 11N of Test Example 3 was obtained by the same method as in Test Example 2, except that the photoradical polymerization initiator was changed from component PI1 to component PI2.

[0129] [Test Example 4] As shown in Figure 9, the light-adjusting sheet 11N of Test Example 4 was obtained by the same method as in Test Example 2, except that the photoradical polymerization initiator was changed from component PI1 to component PI3.

[0130] [Test Example 5] As shown in Figure 9, the light-adjusting sheet 11N of Test Example 5 was obtained by the same method as in Test Example 2, except that the photoradical polymerization initiator was changed from component PI1 to component PI4.

[0131] [Test Example 6] As shown in Figure 9, the light-adjusting sheet 11N of Test Example 6 was obtained by the same method as in Test Example 2, except that the photoradical polymerization initiator was changed from component PI1 to component PI5.

[0132] [Test Example 7] As shown in Figure 9, the light-adjusting sheet 11N of Test Example 7 was obtained by the same method as in Test Example 2, except that the photoradical polymerization initiator was changed from component PI1 to component PI6.

[0133] [Test Example 8] As shown in Figure 10, the light-adjusting sheet 11N of Test Example 8 was obtained by the same method as in Test Example 2, except that the photoradical polymerization initiator was changed from component PI1 to component PI7.

[0134] [Test Example 9] As shown in Figure 10, the light-adjusting sheet 11N of Test Example 9 was obtained by the same method as in Test Example 2, except that the mixing ratio of the photopolymerizable compound was changed as follows, and the photoradical polymerization initiator was changed from component PI1 to component PI8. Glass transition temperature Tg of transparent polymer layer 23P ave The value was 292.8K.

[0135] Ingredient MN1: 13.8% by mass Ingredient MN2: 11.6% by mass Component MN3: 3.1% by mass Ingredient MN4: 11.6% by mass Ingredient MN5: 2.6% by mass

[0136] [Test Example 10] As shown in Figure 10, the light-adjusting sheet 11N of Test Example 10 was obtained by the same method as in Test Example 9, except that the mixing ratio of the photopolymerizable compound was changed as follows. Glass transition temperature Tg of transparent polymer layer 23P ave The value was 298.2K.

[0137] Ingredient MN1: 12.9% by mass Ingredient MN2: 12.0% by mass Component MN3: 2.7% by mass Ingredient MN4: 12.8% by mass Ingredient MN5: 2.3% by mass

[0138] [Test Example 11] As shown in Figure 10, the light-adjusting sheet 11N of Test Example 11 was obtained by the same method as in Test Example 9, except that the mixing ratio of the photopolymerizable compound was changed as follows. Glass transition temperature Tg of transparent polymer layer 23P ave The value was 303.3K.

[0139] Ingredient MN1: 12.1% by mass Component MN2: 12.3% by mass Component MN3: 2.2% by mass Ingredient MN4: 14.0% by mass Ingredient MN5: 2.1% by mass

[0140] [Test Example 12] As shown in Figure 10, the light-adjusting sheet 11N of Test Example 12 was obtained by the same method as in Test Example 9, except that the mixing ratio of the photopolymerizable compound was changed as follows. Glass transition temperature Tg of transparent polymer layer 23P ave The value was 313.5K.

[0141] Ingredient MN1: 10.1% by mass Ingredient MN2: 12.5% ​​by mass Component MN3: 1.8% by mass Ingredient MN4: 16.7% by mass Ingredient MN5: 1.6% by mass

[0142] [Test Example 13] As shown in Figure 10, the dimming sheet 11N of Test Example 13 was obtained by the same method as in Test Example 8, except that the mixing ratio of the liquid crystal mixture LCM, the photopolymerizable compound, and the chain transfer agent CTA was changed as follows. Glass transition temperature Tg of transparent polymer layer 23P ave The value was 259.2K.

[0143] Liquid crystal mixture LCM: 45.0% by mass Ingredient MN1: 25.0% by mass Ingredient MN2: 11.0% by mass Ingredient MN3: 5.0% by mass Component MN4: 2.0% by mass Ingredient MN5: 4.0% by mass Chain transfer agent CTA: 2.0% by mass

[0144] [Test Example 14] As shown in Figure 10, the dimming sheet 11N of Test Example 14 was obtained by the same method as in Test Example 8, except that the mixing ratio of the liquid crystal mixture LCM, the photopolymerizable compound, and the chain transfer agent CTA was changed as follows. Glass transition temperature Tg of transparent polymer layer 23P ave The value was 259.2K.

[0145] Liquid crystal mixture LCM: 64.0% by mass Ingredient MN1: 14.8% by mass Component MN2: 7.0% by mass Component MN3: 3.0% by mass Component MN4: 1.0% by mass Ingredient MN5: 3.0% by mass Chain transfer agent CTA: 1.2% by mass

[0146] [Test Example 15] As shown in Figure 10, the light-adjusting sheet 11N of Test Example 15 was obtained by the same method as in Test Example 9, except that the photoradical polymerization initiator was changed from component PI8 to component PI7. Glass transition temperature Tg of transparent polymer layer 23P ave The value was 292.8K.

[0147] [Test Example 16] As shown in Figure 11, the dimming sheet 11N of Test Example 15 was obtained by the same method as in Test Example 8, except that the mixing ratio of the liquid crystal mixture LCM, the photopolymerizable compound, and the chain transfer agent CTA was changed as follows. Glass transition temperature Tg of transparent polymer layer 23P ave The value was 259.2K.

[0148] Liquid crystal mixture LCM: 40.0% by mass Ingredient MN1: 26.8% by mass Ingredient MN2: 12.0% by mass Ingredient MN3: 5.0% by mass Component MN4: 3.0% by mass Ingredient MN5: 5.0% by mass Chain transfer agent CTA: 2.2% by mass

[0149] [Test Example 17] As shown in Figure 11, the light-adjusting sheet 11N of Test Example 16 was obtained by the same method as in Test Example 16, except that the mixing ratio of the liquid crystal mixture LCM, the photopolymerizable compound, and the chain transfer agent CTA was changed as follows. Glass transition temperature Tg of transparent polymer layer 23P ave The value was 259.2K.

[0150] Liquid crystal mixture LCM: 69.0% by mass Ingredient MN1: 12.6% by mass Component MN2: 5.5% by mass Component MN3: 2.5% by mass Component MN4: 1.2% by mass Ingredient MN5: 2.2% by mass Chain transfer agent CTA: 1.0% by mass

[0151] [Test Example 18] As shown in Figure 11, the dimming sheet 11N of Test Example 17 was obtained by the same method as in Test Example 8, except that the mixing ratio of the liquid crystal mixture LCM and components MN1 and MN2 of the photopolymerizable compound was changed as follows, and the photoradical polymerization initiator was changed from component PI7 to component PI8.

[0152] Liquid crystal mixture LCM: 50.0% by mass Ingredient MN1: 22.0% by mass Component MN2: 9.5% by mass

[0153] [Test Example 19] As shown in Figure 11, the light-adjusting sheet 11N of Test Example 18 was obtained by the same method as in Test Example 18, except that the mixing ratio of the photopolymerizable compound was changed as follows. Glass transition temperature Tg of transparent polymer layer 23P ave The value was 273.1K.

[0154] Ingredient MN1: 18.1% by mass Ingredient MN2: 10.3% by mass Ingredient MN3: 4.0% by mass Component MN4: 6.2% by mass Ingredient MN5: 3.6% by mass

[0155] [Test Example 20] As shown in Figure 11, the light-adjusting sheet 11N of Test Example 20 was obtained by the same method as in Test Example 18, except that the mixing ratio of the photopolymerizable compound was changed as follows. Glass transition temperature Tg of transparent polymer layer 23P ave The value was 282.8K.

[0156] Ingredient MN1: 15.8% by mass Ingredient MN2: 10.8% by mass Component MN3: 3.6% by mass Component MN4: 8.9% by mass Ingredient MN5: 3.1% by mass

[0157] [Evaluation Method] [Bubble Counting] With the entire circumference at the end face of the dimming sheet 11N of each test example sealed, the dimming sheet 11N was stored for 100 days in an environment of 80 °C and a relative humidity of 85%. For sealing the end face, a sealing material (Noftack SC, manufactured by NOF Corporation) (Noftack is a registered trademark) was used. Thereafter, in the dimming sheet 11N of each test example, four 10 cm square counting regions were set so as not to overlap each other. Then, with the dimming sheet 11N placed on the flat surface of the mounting table, the number of bubbles AB contained in each counting region was counted from the viewpoint facing the first transparent conductive sheet 21.

[0158] At this time, for the maximum diameter R M the number of bubbles AB with a maximum diameter R of 1 mm or more was counted. When the bubble AB has a circular shape as viewed from the viewpoint facing the first transparent conductive sheet 21, the diameter of the bubble AB is set as the maximum diameter R M and when the bubble AB has an elliptical shape, the major axis of the bubble AB is set as the maximum diameter R M was set. When the bubble AB has an irregular shape, the diameter of the circle circumscribing the bubble AB was set as the maximum diameter R M was set. The average value of the number of bubbles AB obtained in each counting region was set as the number of bubbles AB per 100 cm 2 in each test example.

[0159] [Peeling of Dimming Sheet] In the dimming sheet 11N of each test example, the ends of the first transparent conductive sheet 21 and the second transparent conductive sheet 22 were held by hand so as to face each other. Next, while the second transparent conductive sheet 22 was fixed to the table, when the end of the first transparent conductive sheet 21 was lifted by 2 mm, it was visually confirmed whether or not peeling proceeded by 2 cm or more from the end of the first transparent conductive sheet 21 into the dimming sheet 11N. Whether or not peeling occurred in the dimming sheet 11N was evaluated at the following two levels.

[0160] A: The amount of peeling toward the inside of the dimming sheet 11N is less than 2 cm. B: The amount of peeling toward the inside of the dimming sheet 11N is 2 cm or more.

[0161] [Calculation of Contrast] The total light transmittance TT when a voltage of 48 V was applied to the dimming sheet 11N of each test example 48V and the total light transmittance TT in the state where no voltage was applied to the dimming sheet 11N of each test example 0V were measured. At this time, using a haze meter (NDH-7000, manufactured by Nippon Denshoku Industries Co., Ltd.), the total light transmittance was measured by a method conforming to JIS K 7361:2000 "Plastics - Method for Determining Total Light Transmittance and Total Light Reflectance". Then, the contrast was calculated by the following formula. (Contrast) = (Total light transmittance TT 48V ) / (Total light transmittance TT 0V )

[0162] [Evaluation Results] The evaluation results of the dimming sheets of each example and each comparative example were as shown in FIGS. 9 to 13.

[0163] As shown in FIGS. 9 to 11, no air bubbles AB were observed in the dimming sheets 11N of Test Examples 1 to 17. In contrast, in the dimming sheet 11N of Test Example 18, the number of air bubbles AB was 19 pieces / 100 cm 2 , and in Test Examples 19 and 20, it was confirmed that the number of air bubbles AB was 1 piece / 100 cm 2 .

[0164] FIG. 12 is an image taken from the viewpoint where the dimming sheet 11N of Test Example 18 faces the first transparent conductive sheet 21. As shown in FIG. 12, in the dimming sheet 11N of Test Example 18, a plurality of large air bubbles AB with a maximum diameter R M of about 1 cm were observed.

[0165] As is clear from the evaluation results of Test Examples 1 to 8, when any of components PI1 to PI7 are included as the photoradical polymerization initiator, no bubbles AB are formed in the light-adjusting sheet 11N. In contrast, as is clear from the evaluation results of Test Examples 9 to 12 and Test Examples 18 to 20, even when component PI8 is included as the photoradical polymerization initiator, the glass transition temperature Tg of the transparent polymer layer 23P is not formed. ave When the temperature is 290K or higher, specifically between 292.8K and 313.5K, no bubbles AB are formed. Furthermore, as is clear from the evaluation results of Test Example 15, when component PI7 is included as a photoradical polymerization initiator and the glass transition temperature of the transparent polymer layer 23P is 290K or higher, no bubbles AB are formed.

[0166] As shown in Figures 9 to 11, in Test Examples 1 to 16 and Test Examples 18 to 20, the evaluation result for peeling of the dimming sheet 11N was A, while in Test Example 17, the evaluation result for peeling of the dimming sheet 11N was B. From these results, it can be said that when the mixing ratio of the liquid crystal mixture LCM in the dimming layer 23 is 69.0 mass%, the proportion of the transparent polymer layer 23P in the dimming layer 23 is low, which reduces the adhesion between the dimming layer 23 and the transparent conductive sheets 21 and 22. As a result, peeling is more likely to occur between the dimming layer 23 and the transparent conductive sheets 21 and 22.

[0167] The contrast of the dimmable sheet 11N was found to be less than 2.0 in test example 3, between 2.0 and 3.0 in test examples 2 and 4, and between 3.0 and 4.0 in test examples 5, 10, 11, 12, and 15. The contrast of the dimmable sheet 11N was found to be between 4.0 and 5.0 in test examples 6, 7, 9, 13, and 14, and above 5.0 in test examples 8, 18 to 20.

[0168] In Test Example 16, even when a voltage of 48 V was applied to the dimming sheet 11N, the dimming sheet 11N did not change from the opaque state. From these results, when the blending ratio of the liquid crystal mixture LCM in the dimming layer 23 is 40.0% by mass, the proportion of the liquid crystal mixture LCM in the dimming layer 23 is low, and thus it can be said that a phase-separated dimming layer 23 that can change the haze of the dimming sheet 11N depending on the application or non-application of voltage cannot be formed. Also, in Test Example 16, peeling occurred between the dimming layer 23 and the transparent conductive sheets 21 and 22, so the contrast was not evaluated.

[0169] Figure 13 shows the contrast of the dimming sheet 11N and the glass transition temperature Tg ave as a scatter diagram. In Figure 13, the open triangles indicate the contrast and the glass transition temperature Tg ave in Test Example 8, the open diamonds indicate Test Example 6, and the open squares indicate Test Example 7. The filled black circles indicate the contrast and the glass transition temperature Tg ave in Test Examples 9, 10, 11, and 12 in order from the lower glass transition temperature Tg ave The crosses indicate the contrast and the glass transition temperature Tg ave in Test Examples 18, 19, and 20 in order from the lower glass transition temperature Tg ave respectively.

[0170] As shown in Figure 13, from the comparison of the evaluation results of Test Example 6 to Test Example 8, it is considered that the contrast obtained in the dimming sheet 11N differs due to the difference in the sensitivity of the photopolymerization radical initiator. When a more sensitive photoradical polymerization initiator is used, the liquid crystal composition 23LC and the transparent polymer layer 23P are more likely to be clearly phase-separated, and thus it is considered that the proportion of the dichroic dye contained in the void 23D among the total amount of the dichroic dye increases.

[0171] From the comparison of the evaluation results of Test Example 9 to Test Example 12 and Test Example 18 to Test Example 20, from the viewpoint of increasing the contrast of the dimming sheet 11N, the glass transition temperature Tg aveit can be said that it is preferable that it is lower. From such results, in order to smoothly drive the liquid crystal mixture LCM in the gap 23D, the glass transition temperature Tg of the transparent polymer layer 23P ave is considered to be preferably lower. In this regard, the glass transition temperature Tg of the transparent polymer layer 23P ave is 290 K or higher and 315 K or lower, preferably 292.8 K or higher and 313.5 K or lower, whereby the generation of air bubbles AB in the dimming sheet 11N and the reduction of the contrast in the dimming sheet 11N can be suppressed.

[0172] As described above, according to one embodiment of the dimming sheet, the following effects can be obtained. (1) Since the glass transition temperature Tg of the transparent polymer layer 23P ave is 292 K or higher, the dimming layer 23 is less likely to soften even when the dimming sheets 11N and 11R are heated. Therefore, the gas G generated in the transparent polymer layer 23P during the production of the dimming sheets 11N and 11R is suppressed from moving within the dimming sheets 11N and 11R due to the heating of the dimming sheets 11N and 11R, thereby suppressing the aggregation of the gas G. As a result, after the formation of the dimming layer 23, the formation of air bubbles AB large enough to be visually confirmed in the dimming sheets 11N and 11R is suppressed.

[0173] (2) When the dimming sheets 11N and 11R satisfy condition 3, even if the photo radical polymerization initiator undergoes intramolecular cleavage, a compound having a molecular weight small enough to be a gas at room temperature does not occur. Therefore, the generation of air bubbles AB in the dimming sheets 11N and 11R is further suppressed.

[0174] (3) When the dimming sheets 11N and 11R satisfy any one of conditions 4 to 6, the generation of the gas G in the dimming layer 23 during the production of the dimming sheets 11N and 11R can be suppressed. In addition, the contrast between the state in which the dimming sheets 11N and 11R are transparent and the state in which they are opaque can also be enhanced.

[0175] (4) Even when the dimming sheets are left undisturbed for a long period of time in a high-temperature and high-humidity environment, the formation of air bubbles AB in the dimming sheets 11N and 11R is suppressed. (5) When the light-adjusting sheets 11N and 11R contain a dichroic dye, the effect of preventing air bubbles AB from forming in the light-adjusting sheets 11N and 11R can be more pronounced.

[0176] [Note] According to the above embodiment, the following technical concept can be derived. [Note 1] A first transparent conductive sheet comprising a first transparent electrode layer and a first transparent substrate supporting the first transparent electrode layer, A second transparent conductive sheet comprising a second transparent electrode layer and a second transparent substrate supporting the preceding second transparent electrode layer, The device comprises a light-adjusting layer located between the first transparent electrode layer and the second transparent electrode layer, A dimming sheet is configured such that the dimming layer can be switched between a transparent state and an opaque state by switching between a state in which a voltage is applied between the first transparent electrode layer and the second transparent electrode layer and a state in which the voltage is not applied, The aforementioned dimming layer is A transparent polymer layer containing multiple polymers of one or more photopolymerizable compounds, defining multiple voids, Multiple spacers dispersed in the transparent polymer layer, A liquid crystal composition comprising one or more liquid crystal compounds and located within the void, The ratio of the mass of the one or more liquid crystal compounds to the mass of the light-adjusting layer is 45% by mass or more and 65% by mass or less. The polymer of the photopolymerizable compound includes atomic groups located at the terminals of the polymer. The atomic group is an atomic group generated from the photoradical polymerization initiator by intramolecular cleavage of the photoradical polymerization initiator that occurs during polymerization of the photopolymerizable compound. The transparent polymer layer contains one or more atomic groups derived from at least one of the photoradical polymerization initiators represented by the following chemical formulas (1) to (5). [ka] In Chemical Formula (1), R 1 is an arbitrary atomic group, and R 2 is a hydrocarbon group having 5 or more carbon atoms

Chemical Structure

Chemical Structure

Chemical Structure

[0177] According to the above dimming sheet, even if the photo radical polymerization initiator undergoes intramolecular cleavage, a compound having a molecular weight small enough to be a gas at normal temperature does not occur. Therefore, after the formation of the dimming layer, the formation of bubbles large enough to be visually confirmed in the dimming sheet is suppressed.

Explanation of Symbols

[0178] 10N… Normal type dimming device​ 10R... Reverse type dimmer 11N, 11R… Dimmable sheet 21…First transparent conductive sheet 21A...first transparent electrode layer 21B...First transparent base material 21C…First orientation layer 22…Second transparent conductive sheet 22A…Second transparent electrode layer 22B...Second transparent base material 22C...Second orientation membrane 23…Dimming layer 23D…Void 23P…Transparent polymer layer

Claims

1. A first transparent conductive sheet comprising a first transparent electrode layer and a first transparent substrate supporting the first transparent electrode layer, A second transparent conductive sheet comprising a second transparent electrode layer and a second transparent substrate supporting the second transparent electrode layer, The device comprises a light-adjusting layer located between the first transparent electrode layer and the second transparent electrode layer, A dimming sheet is configured such that the dimming layer can be switched between a transparent state and an opaque state by switching between a state in which a voltage is applied between the first transparent electrode layer and the second transparent electrode layer and a state in which the voltage is not applied, The aforementioned dimming layer is A transparent polymer layer comprising multiple polymers composed of one or more photopolymerizable compounds, defining multiple voids, Multiple spacers dispersed in the transparent polymer layer, A liquid crystal composition comprising one or more liquid crystal compounds and located within the void, The ratio of the mass of the one or more liquid crystal compounds to the mass of the light-adjusting layer is 45% by mass or more and 65% by mass or less. Glass transition temperature (Tg) of each photopolymerizable compound homopolymer ｋ , and the mass ratio W of each photopolymerizable compound ｋ The glass transition temperature Tg of the transparent polymer layer is calculated using the following formula (1). ａｖｅ However, it is 292K or higher. [Math 1] Dimming sheet.

2. The polymer of the photopolymerizable compound includes atomic groups located at the terminals of the polymer. The atomic group is an atomic group generated from the photoradical polymerization initiator by intramolecular cleavage of the photoradical polymerization initiator that occurs during polymerization of the photopolymerizable compound. The transparent polymer layer contains one or more atomic groups derived from at least one of the photoradical polymerization initiators represented by the following chemical formulas (1) to (4). 【Chemistry 1】 In chemical formula (1), R １ R is an arbitrary group of atoms, ２ This is a hydrocarbon group with 5 or more carbon atoms. 【Chemistry 2】 In Chemical Formula (2), R ３ is an arbitrary atomic group, R4 is a hydroxy group or an amino group, R ５ and R ６ are arbitrary atomic groups. Chemical Formula (2) may have one or more bonds between the atomic group containing R ５ and the atomic group containing R ６ ​ 【Transformation 3】 In chemical formula (3), R ７ , R ８ , and, R ９ Each of these is a phenyl group, and the hydrogen atoms in each phenyl group may be substituted with other functional groups. 【Chemistry 4】 In chemical formula (4), R １０ , R １１ , and, R １２ Each of these is a phenyl group, and the hydrogen atoms in each phenyl group may be substituted with other functional groups. The dimming sheet according to claim 1.

3. The polymer contained in the transparent polymer layer includes the atomic group derived from the photoradical polymerization initiator represented by the chemical formula (1), In the photoradical polymerization initiator represented by the chemical formula (1), R ２ is a phenyl group The dimming sheet according to claim 2.

4. The polymer contained in the transparent polymer layer is The photoradical polymerization initiator represented by the chemical formula (3), R ７ and R ８ is a phenyl group, R ９ The atomic group derived from the photoradical polymerization initiator, wherein the group is a mesityl group, The photoradical polymerization initiator represented by the chemical formula (4), R １０ is a phenyl group, R １１ and R １２ The atomic group comprises the photoradical polymerization initiator having a mesityl group. The dimming sheet according to claim 2 or 3.

5. After sealing the entire circumference of the end face of the dimming sheet and storing it for 100 days in an environment of 80°C and 85% relative humidity, the number of air bubbles in a plan view facing the first transparent conductive sheet is 1 bubble / 100 cm². ２ Less than A dimming sheet according to any one of claims 1 to 3.

6. The liquid crystal composition further comprises a dichroic dye A dimming sheet according to any one of claims 1 to 3.

Images