JP2018112701A - Flexible light control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light control device that exhibits good display characteristics with an appropriate driving voltage both at bending and after bending.SOLUTION: A flexible light control device comprises: a pair of substrates; a light control layer 30 that is held between the substrates and contains a first polymer and a liquid crystal compound; and partition walls 20 that have a continuous structure dividing the light control layer 30 into a plurality of sections 32 and contain a second polymer. The content of the first polymer in the light control layer 30 is 20 weight% or less; the content of the second polymer in the partition walls 20 is 60 weight% or more; the arrangement interval of the partition walls 20 is 10 mm or less; the width of the partition wall 20 is 1% to 100% with respect to the length of one side of the section 32.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a flexible light control device. More specifically, the present invention relates to a flexible light control device that changes the scattering state of transmitted light in response to application of a voltage.

  Conventionally, a light control device using a light scattering effect in a composite of a polymer and a liquid crystal material has been developed. In such a composite, since the liquid crystal material has a structure in which the liquid crystal material is phase-separated or dispersed in the polymer matrix, the refractive index of the polymer and the liquid crystal material is matched, and a voltage is applied to the composite to apply the liquid crystal. By changing the orientation of the material, the transmission mode for transmitting light and the scattering mode for scattering light can be controlled.

  For the polymer dispersion type (for example, PDLC, PNLC) light control device, various configurations have been proposed for the purpose of improving impact resistance. For example, in the composite, an operation region that changes a scattering state of transmitted light in response to application of a voltage and a liquid crystal immobilization region that does not change transmittance due to voltage are provided (Patent Document 1). Providing a plurality of columnar resin aggregates formed from a polymer and having a thin central part (Patent Document 2), mainly comprising a polymer constituting the composite, and dividing the region occupied by the composite into a plurality of regions Providing a structure (Patent Document 3) has been proposed.

JP 2005-274599 A JP 2011-154388 A JP 2002-287127 A

  According to the above configuration, a certain impact resistance can be obtained. On the other hand, when the light control device is a flexible device, mechanical strength against bending and bending of the upper and lower substrates accompanying bending is insufficient, and there is a possibility that white turbidity may occur after bending. Moreover, when the polymer content in the composite increases, the driving voltage tends to increase.

  The present invention has been made to solve the above problems, and a main object of the present invention is to provide a light control device that exhibits good display characteristics with an appropriate driving voltage even during and after bending.

According to one aspect of the present invention, a pair of substrates, a light control layer that is sandwiched between the substrates and includes a first polymer and a liquid crystal compound, and a continuous structure that partitions the light control layer into a plurality of partitions. A flexible light control device is provided having a partition including a second polymer. The content of the first polymer in the light control layer is 20% by weight or less, the content of the second polymer in the partition wall is 60% by weight or more, and the spacing between the partition walls is It is 10 mm or less, and the width of the partition wall is 1% to 100% with respect to the length of one side of the partition.
In one embodiment, the ratio of the area of the said light control layer with respect to the sum total of the area of the said light control layer and the said partition in planar view is 60% or more.
In one embodiment, the first polymer and the second polymer are polymerization reactants of the same monomer component.
In one embodiment, the linear expansion coefficient of the substrate is 100 ppm or less.
In one embodiment, a hard coat layer is provided on the opposite side of the light control layer of at least one of the substrates.
In one embodiment, a protective layer is provided on the opposite side of the light control layer of at least one of the substrates.
In one embodiment, the first polymer and the second polymer comprise a liquid crystal polymer.
In one embodiment, the change of the haze value in the bending of the curvature radius of 100 mm of the light control device is 1% or less.

  According to the present invention, the light control layer is divided into a plurality of sections by the partition wall having a predetermined continuous structure, and the polymer content in the partition wall and the light control layer is adjusted, so that it is appropriate even during and after bending. A dimming device is provided that exhibits good display characteristics with a low driving voltage.

1 is a schematic cross-sectional view of a light control device according to one embodiment of the present invention. It is a schematic plan view explaining an example of the continuous structure of a partition. It is the schematic explaining an example of the manufacturing method of the light modulation device of this invention.

  Hereinafter, although one embodiment of the present invention is described, the present invention is not limited to these embodiments.

A. Light control device A-1. Overall Configuration FIG. 1 is a schematic cross-sectional view of a light control device according to one embodiment of the present invention. The light control device 100 includes a pair of substrates 10a and 10b, a light control layer 30 sandwiched between the substrates 10a and 10b, and a partition wall 20 that partitions the light control layer 30 into a plurality of partitions 32. The substrates 10 a and 10 b include the alignment film 12, the transparent electrode 14, and the base material 16 in this order, and are arranged so that the alignment film 12 is in contact with the light control layer 30. The alignment film 12 may be omitted depending on the driving method of the light control device.

  The dimming device 100 may further include any appropriate functional layer depending on the purpose. Examples of the functional layer include a hard coat layer, a pressure-sensitive adhesive layer, and a protective layer. These are disposed on either one or both of the substrates 10a and 10b (on the side where no electrode is provided).

  The total thickness of the light control device 100 may be, for example, 30 μm to 800 μm, preferably 50 μm to 450 μm.

  The light control device of the present invention has flexibility. In the light control device of the present invention, the change in haze value (change in haze value in the transmission mode) in bending with a radius of curvature of 100 mm is preferably 1% or less, more preferably 0.8% or less.

  The light control device of the present invention can switch between a transparent state (transmission mode) and an opaque state (scattering mode) by switching between application / non-application of voltage.

  Voltage refers to alternating and / or direct voltage. The applied waveform is not particularly limited, and may be a direct current, an alternating current, a pulse, or a synthesized wave thereof. In the case of a DC voltage, preferably 0.5 msec or more, and in the case of an AC voltage, any of a sine wave, a rectangular wave, a triangular wave, or a composite wave thereof may be used. In this case, preferably, the switching can be performed by applying a pulse width of 0.5 msec or more.

  The drive voltage of the light control device of the present invention is typically 60 V or less, preferably 30 V or less for DC voltage, 120 Vp-p or less, preferably 90 Vp-p or less for AC voltage, and a maximum value of 60 V for pulse voltage. Hereinafter, the maximum value is preferably 30 V or less.

  The haze of the light control device of the present invention is preferably 15% or less in the transmission mode, and preferably 70% or more in the scattering mode. Particularly preferably, it is 10% or less in the transmission mode and 85% or more in the scattering mode. When the haze is less than 70% in the scattering mode, an image through the light control device is seen, and the hiding property is lowered.

A-2. Light Control Layer The light control layer includes a first polymer and a liquid crystal compound. More specifically, the light control layer comprises a composite (first polymer and liquid crystal) obtained by polymerizing a liquid crystal composition containing a monomer component for producing the first polymer and a non-polymerizable liquid crystal compound. Complex with a compound). In the composite, the liquid crystal compound exists in a phase separated or dispersed state in the network structure formed by the first polymer.

  The liquid crystal compound preferably exhibits substantially the same refractive index as the first polymer in the aligned state. Therefore, in a state where the degree of orientation of the liquid crystal compound is high, light incident on the light control layer can pass through the light control layer without greatly bending the traveling direction. At this time, the light control layer is a transmissive mode, and the haze value can be, for example, 15% or less, preferably 10% or less, more preferably 7% or less. The haze value can be measured according to, for example, JIS K7136.

  On the other hand, in a state where the degree of orientation of the liquid crystal compound is low, the orientation of the liquid crystal compound becomes irregular, and thus the difference in refractive index between the first polymer and the liquid crystal compound increases. In this state, the light incident on the light control layer is scattered with the traveling direction greatly bent due to the difference in refractive index. At this time, a light control layer is a scattering mode, and a haze value can be 70% or more, for example, Preferably it is 80% or more, More preferably, it can be 85% or more.

  The driving method of the light control device 100 in the illustrated example is a reverse mode, which is a scattering mode when a voltage is applied, and a transmission mode when no voltage is applied. Specifically, the alignment action of the alignment film 12 provided on the surfaces of the transparent electrodes 14 of the substrates 10a and 10b aligns the liquid crystal compound when no voltage is applied and becomes a transmission mode. Disturbed and becomes scattering mode. Note that the alignment film can be omitted as long as the liquid crystal compound can be aligned when no voltage is applied (for example, when the electrode surface is directly rubbed).

  In the light control device in the normal mode, the transmission mode is set when a voltage is applied, and the scattering mode is set when no voltage is applied. Specifically, the alignment film is omitted, the liquid crystal compound is aligned when a voltage is applied, and becomes a transmission mode, and the alignment of the liquid crystal compound is disturbed when the voltage is released and becomes a scattering mode.

  As the liquid crystal compound contained in the light control layer, any suitable non-polymerization type liquid crystal compound is used. For example, nematic, smectic, and cholesteric liquid crystal compounds can be given. A nematic liquid crystal compound is preferably used because excellent transparency can be realized in the transmission mode. The dielectric anisotropy may be positive or negative.

  Specific examples of the liquid crystal compound include cyanobiphenyl, cyanophenylcyclohexane, cyanophenyl ester, benzoic acid phenyl ester, phenylpyrimidine compounds, and mixtures thereof as described in JP-A-11-174211, etc. And a low-molecular liquid crystal compound exhibiting a nematic phase or a smectic phase at room temperature or high temperature. Specific examples of such a low-molecular liquid crystal compound include biphenyl, phenylbenzoate, cyclohexylbenzene, azoxybenzene, azobenzene, azomethine, and terphenyl, as described in JP-A-11-153787. And various low molecular liquid crystal compounds such as biphenylbenzoate, cyclohexylbiphenyl, phenylpyrimidine, cyclohexylpyrimidine, and cholesterol. These low-molecular liquid crystal compounds may be used alone or in combination.

  Content of the liquid crystal compound in a light control layer is 80 weight% or more, for example, Preferably it is 85 weight%-97 weight%, More preferably, it is 90 weight%-95 weight%. If the content of the liquid crystal compound is in this range, the amount of change in haze between the transmission mode and the scattering mode can be sufficiently increased with an appropriate driving voltage.

  The first polymer contained in the light control layer can be appropriately selected according to the light transmittance, the refractive index of the liquid crystal compound, and the like. The first polymer is typically an active energy ray curable resin, and preferably a liquid crystal polymer, a (meth) acrylic resin, a silicone resin, an epoxy resin, a fluorine resin, a polyester resin, a polyimide resin, or the like. Can be used. These may be used alone or in combination of two or more. Preferably, the first polymer contains at least one liquid crystal polymer because matching of the refractive index with the liquid crystal compound is facilitated.

  The liquid crystal polymer is preferably aligned in a predetermined direction and the alignment state is fixed. Since the alignment state of the liquid crystal polymer is fixed, switching between the transmission mode and the scattering mode can be suitably performed through the change in the alignment state of the liquid crystal compound. Such a liquid crystal polymer is obtained by using a polymerization type monomer (which may include a bifunctional or higher functional crosslinking monomer) as a liquid crystal monomer, aligning the liquid crystal monomer, and then polymerizing or crosslinking the liquid crystal monomers. obtain. Here, a polymer is formed by polymerization, and a network structure is formed by crosslinking, but these are non-liquid crystalline. Therefore, in the obtained liquid crystal polymer, for example, a transition to a liquid crystal phase, a glass phase, or a crystal phase due to a temperature change specific to a liquid crystal compound does not occur.

  The temperature range in which the liquid crystal monomer exhibits liquid crystal properties varies depending on the type. Specifically, the temperature range is preferably 40 ° C to 120 ° C, more preferably 50 ° C to 100 ° C, and most preferably 60 ° C to 90 ° C.

  Any appropriate liquid crystal monomer can be adopted as the liquid crystal monomer. For example, polymerized mesogenic compounds described in JP-T-2002-533742 (WO00 / 37585), EP358208 (US52111877), EP66137 (US4388453), WO93 / 22397, EP02661712, DE195504224, DE44081171, and GB2280445 can be used. Specific examples of such a polymerization type mesogenic compound include, for example, trade name LC242 of BASF, trade name E7 of Merck, and trade name LC-Silicon-CC3767 of Wacker-Chem. As the liquid crystal monomer, for example, a nematic liquid crystal monomer is preferable.

  Content of the 1st polymer in a light control layer is 20 weight% or less, Preferably they are 3 weight%-15 weight%, More preferably, they are 5 weight%-10 weight%. When the content of the first polymer is less than 3% by weight, problems such as difficulty in producing a scattering effect and low adhesion to the substrate may occur. On the other hand, when the content of the first polymer exceeds 20% by weight, the driving voltage increases, the dimming function decreases (the haze value in the transmission mode increases, the amount of change in haze between the transmission mode and the scattering mode) May become a problem.

  The light control layer is typically formed by photopolymerizing the liquid crystal composition. In addition to the monomer component and the liquid crystal compound, the liquid crystal composition may further include any appropriate component depending on the purpose. For example, the liquid crystal composition may further include a chiral agent. By using a chiral agent, the liquid crystal compound or the liquid crystal polymer can have cholesteric orientation. The type and amount of the chiral agent can be appropriately determined according to a desired set value such as a helical pitch. For example, the liquid crystal composition may further include a polymerization initiator. The type and addition amount of the polymerization initiator can be appropriately determined according to the type and composition of the monomer component. Examples of other optional components include an antioxidant, a plasticizer, and a pigment. The content of optional components in the liquid crystal composition can be, for example, 10% by weight or less.

  The thickness of the light control layer may be, for example, 3 μm to 30 μm, preferably 10 μm to 25 μm. If the thickness is within this range, good display characteristics can be obtained with an appropriate driving voltage.

A-3. Partition Wall The partition wall has a continuous structure that partitions the light control layer into a plurality of sections. Typically, the partition wall has a continuous structure in a lattice shape in plan view, and is provided so as to connect two substrates. With such a configuration, it is possible to prevent the liquid crystal compound from flowing or leaking due to bending or bending of the upper and lower substrates accompanying the bending. It can also function as a spacer. As will be described later, the light control layer and the partition walls can be formed as regions having different polymer contents from one liquid crystal composition depending on exposure conditions. Therefore, the partition does not need to have a wall surface independent of the light control layer, and may be provided continuously with the light control layer. When the partition wall is provided continuously with the light control layer, the following description regarding the shape of the partition wall is a description of the contour shape of the region adjacent to the light control layer and having a polymer content higher than that of the light control layer. .

  The partition wall is preferably provided so that the angle formed between the wall surface and the substrate is substantially a right angle (90 ° ± 5 °, preferably 90 ° ± 2 °). In one embodiment, the partition has a substantially rectangular parallelepiped shape. By adopting such a shape, it is possible to suitably prevent the liquid crystal compound from flowing or leaking due to bending and displacement of the upper and lower substrates accompanying the bending.

  The above-mentioned “continuous structure in the form of a lattice in a plan view” means that, in a plan view, partition walls extend in a plurality of directions and form periodically separated partitions. The number of extending directions of the partition walls is preferably two directions (in this case, the shape of the lattice is a quadrangle) or three directions (in this case, the shape of the lattice is a triangle or a hexagon), and more preferably in two directions.

  When the partition wall extends in two directions, the angle formed between the first direction and the second direction is not limited as long as the effect of the present invention is obtained, and is, for example, 80 ° to 100 °, preferably 85. It is (degree)-95 degrees, More preferably, it is 88 degrees-92 degrees. By adopting such a configuration, the structure can be suitably maintained even when bending and bending of the upper and lower substrates accompanying the bending are applied.

  FIG. 2 is a schematic plan view for explaining an example of the continuous structure of the partition walls. In the illustrated example, the partition wall 20 extends in a first direction parallel to the width direction of the light control device and a second direction orthogonal to the first direction at a predetermined arrangement interval in plan view. A lattice pattern is formed.

The arrangement interval D of the partition walls extending in the same direction is 10 mm or less, preferably 1 mm or less, more preferably 30 μm to 500 μm. By partitioning in this way, the structure can be suitably maintained even when bending and shearing of the upper and lower substrates accompanying the bending are applied. In addition, when the arrangement interval differs depending on the extending direction, the arrangement interval D means the maximum interval. When the arrangement interval differs depending on the extending direction, the maximum interval D _MAX and the minimum interval D _MIN satisfy, for example, a relationship of 1 <D _MAX / D _MIN ≦ 20, and preferably 1 <D _MAX / D _MIN ≦ 10. Satisfy the relationship.

  The width W of the partition wall is 1% to 100%, preferably 3% to 30%, more preferably 5% to 20% with respect to the length of one side of the section in plan view. By setting it as such a ratio, contrast can be raised, maintaining mechanical strength. In addition, when the length of the side which forms a division is different like the side A and the side B of an example of illustration, the length of all the sides shall satisfy | fill the said ratio. Further, the length of the side is obtained as the distance between the intersections of the center lines in the width direction of the partition wall (for example, the length of the side B in the illustrated example is L).

  The width W of the partition wall may be, for example, 3 μm to 50 μm, preferably 5 μm to 30 μm, more preferably 8 μm to 20 μm.

  The partition includes a second polymer. The content of the second polymer in the partition wall is larger than the first polymer content in the light control layer. The content of the second polymer in the partition wall is 60% by weight or more, for example 70% by weight or more, preferably more than 75% by weight and 95% by weight or less, more preferably 80% by weight to 95% by weight. %. With such a content, the wall structure can be suitably maintained even when bending and bending of the upper and lower substrates accompanying bending are applied. In addition, an excessive increase in drive voltage can be suppressed.

  As said 2nd polymer, the thing similar to a 1st polymer can be illustrated. The second polymer may be the same as or different from the first polymer. Preferably, the first polymer and the second polymer contain the same monomer as a structural unit. More specifically, the first polymer and the second polymer preferably include a polymerization reaction product of the same monomer component, more preferably include a liquid crystal polymer that is a polymerization reaction product of the same liquid crystal monomer, and more preferably the same. A liquid crystal polymer that is a polymerization reaction product of a cross-linked liquid crystal monomer When the liquid crystal polymer has a crosslinked structure, the wall structure can be suitably maintained against the pressure in the surface direction, shear stress, and the like.

  In one embodiment, the light control layer and the partition may be formed as regions different from each other in the content of the polymer or the like due to a difference in exposure conditions from one liquid crystal composition. In the embodiment, the partition wall includes components (for example, a liquid crystal compound, a chiral agent, and an antioxidant) contained in the liquid crystal composition in addition to the second polymer (polymerization reaction product of the same monomer component as the first polymer). Agents, etc.) may be included as well.

  The content of the liquid crystal compound in the partition walls is, for example, 40% by weight or less, preferably 3% by weight to 20% by weight, and more preferably 5% by weight to 10% by weight.

  The partition wall has substantially no change in light transmittance when a voltage is applied and when no voltage is applied. In the light control device in the reverse mode, the light transmittance (wavelength 550 nm) of the partition wall is, for example, 30% to 95%, preferably 60% to 90% with respect to the incident polarized light on the alignment axis.

  In one embodiment, the ratio (aperture ratio) of the area of the light control layer to the total area of the light control layer and the partition wall in a plan view is 60% or more, preferably 70% or more, more preferably 80. % To 95%. When the area (aperture ratio) of the light control layer is 60% or more, the light control function can be suitably exhibited.

A-4. Substrate The substrate preferably has a flexibility that can be bent to a radius of curvature of 100 mm or less, more preferably 80 mm or less without adversely affecting the optical properties.

  The substrate preferably has a linear expansion coefficient of 100 ppm or less, more preferably 50 ppm or less. When the linear expansion coefficient is within the above range, there is an advantage that the substrate is hardly deformed due to bending and bending of the upper and lower substrates accompanying the bending. The linear expansion coefficient is measured according to JIS K7197.

  The light transmittance (wavelength 550 nm) of the substrate is preferably 80% or more, more preferably 85% or more, and further preferably 90% or more. If the light transmittance is within such a range, excellent transparency in the transmission mode can be realized.

  In the illustrated example, for both the pair of substrates 10a and 10b, the transparent electrode and the alignment film are provided in this order on the base material. However, as described above, the alignment film depends on the driving mode of the light control device and the like. Can be omitted. The transparent electrode need not be provided on both of the pair of substrates, and may be provided only on one of the substrates depending on the purpose.

  The substrate is not limited as long as it has flexibility, and may be a resin substrate or a glass substrate. The substrate is preferably a resin substrate. As a material for forming the resin base material, polyester resins, (meth) acrylic resins, olefin resins, cyclic olefin resins, polycarbonate resins, polyurethane resins, cellulose resins, styrene resins, and the like can be preferably used. . Specific examples of polyester resins include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), isophthalic acid, cycloaliphatic dicarboxylic acid containing cyclohexane ring, alicyclic diol, etc. Copolymerized PET containing PET (PET-G), other polyesters, and copolymers and blends thereof. These materials may be used alone or in combination of two or more.

  The thickness of the substrate can be, for example, 20 μm to 500 μm, preferably 50 μm to 300 μm.

The transparent electrode can be formed using a metal oxide such as indium tin oxide (ITO), zinc oxide (ZnO), tin oxide (SnO ₂ ), for example. Alternatively, the transparent electrode can be formed of silver nanowires (AgNW), carbon nanotubes (CNT), an organic conductive film, a metal layer, or a laminate thereof. The transparent electrode can be patterned into a desired shape according to the purpose. For example, the blind function can be suitably imparted to the light control device by forming the transparent electrode in a pattern of vertical stripes, horizontal stripes, or lattices.

  The alignment film can be formed, for example, by subjecting a coating film such as polyimide or polyvinyl alcohol to a rubbing treatment with a cloth such as rayon.

A-5. Other Functional Layers The hard coat layer can be formed by, for example, a method of adding a cured film excellent in hardness, sliding properties, etc. with an appropriate ultraviolet curable resin such as acrylic or silicone to the surface.

  The protective layer is, for example, a cellulose resin such as diacetyl cellulose or triacetyl cellulose, an (meth) acrylic resin, a cycloolefin resin, an olefin resin such as polypropylene, an ester resin such as a polyethylene terephthalate resin, or a polyamide resin. And a resin film formed from a polycarbonate resin, a copolymer resin thereof, or the like. The thickness of the protective layer is typically 10 μm to 100 μm.

  The pressure-sensitive adhesive layer can be formed of, for example, an acrylic pressure-sensitive adhesive having an acrylic polymer as a base polymer. Although the thickness of an acrylic adhesive layer can be suitably adjusted according to the material and use of a to-be-adhered body, it is 5 micrometers-50 micrometers normally. Typically, it is formed with an acrylic adhesive.

  The said adhesive layer can comprise the outermost layer of a light control device. The pressure-sensitive adhesive layer may be protected by a separator until it is used.

B. Manufacturing method of light control device Arbitrary appropriate methods may be selected as a manufacturing method of the light control device of this invention.

  In one embodiment, in the method for manufacturing a light control device of the present invention, a coating layer is formed by applying a liquid crystal composition containing the liquid crystal compound, a monomer component (for example, a liquid crystal monomer), etc. on one substrate. A step of laminating the other substrate on the coating layer to produce a laminate having a pair of substrates and a coating layer sandwiched between the substrates; a first activity in a predetermined pattern on the laminate; A step of performing energy beam irradiation, and a step of performing second active energy beam irradiation on the entire surface of the laminate. According to the manufacturing method, the partition wall and the substrate can be firmly fixed, and the partition wall and the light control layer can have physical integrity, so that bending of the upper and lower substrates due to bending and bending is loaded. However, the structure can be more suitably maintained.

  The manufacturing method of the above embodiment will be described more specifically with reference to FIG. First, as shown in FIG. 3A, a coating layer 40 is formed by applying a liquid crystal composition to the alignment film side surface of the substrate 10a.

  The compounding ratio (monomer component: liquid crystal compound (weight basis)) of the liquid crystal compound and the monomer component in the liquid crystal composition is, for example, 8:92 to 25:75, preferably 10:90 to 20:80. The liquid crystal composition is used as a photosensitive material by using a photosensitive monomer component, blending a photoinitiator, and the like.

  Any appropriate method can be adopted as a coating method. Examples thereof include a roll coating method, a spin coating method, a wire bar coating method, a dip coating method, a die coating method, a curtain coating method, a spray coating method, a knife coating method (comma coating method and the like). The coating layer may be naturally dried or heat dried as necessary.

  Next, as shown in FIG. 3B, the substrate 10 b is laminated on the coating layer 40 so that the alignment film side surface faces the coating layer 40.

  Next, as shown in FIG. 3C, first active energy ray irradiation is performed through a mask 50 having an opening pattern corresponding to the planar shape of the partition wall. Thereby, the monomer component is polymerized in the active energy ray irradiation region of the coating layer 40. As the active energy ray, ionizing radiation such as ultraviolet ray, electron beam, α ray, β ray, γ ray and the like is used. Of these, ultraviolet rays are preferable.

  Next, as shown in FIG. 3D, the entire surface of the coating layer 40 is irradiated with the second active energy ray without a mask. Thereby, the polymerization reaction proceeds in the entire coating layer 40, and the light control layer 30 partitioned into a plurality of partitions 32 by the partition walls 20 and the partition walls 20 is formed.

The irradiation condition of ultraviolet rays can be appropriately set according to the type of monomer component. For example, the ultraviolet irradiation condition in the first active energy ray irradiation can be appropriately selected according to the transmittance of the substrate material and the absorption wavelength of the photopolymerization initiator, and preferably stronger than the second active energy ray irradiation. Irradiated with intensity. Specifically, the coating layer containing the monomer component and the liquid crystal compound is preferably 5 mW / cm ^{2 to} 300 mW / cm ² , more preferably 5 mW / cm ^{2 to} 200 mW / cm ² , and even more preferably 20 mW / cm ^2. Irradiation with an intensity of ˜150 mW / cm ² . Moreover, it is preferable that the first active energy ray is collimated light having high straightness from the irradiation source. In this process, the formation of the partition structure can be almost completed. Further, by this pattern exposure, a monomer (more specifically, a polymer that is a polymerization reaction product) is locally deposited from the liquid crystal composition to form a partition wall. By improving the solubility with the liquid crystal compound, the liquid crystal compound is easily taken into the partition. As a result, the polymer content in the partition walls can be reduced, and the strength can be reduced at the same time. Therefore, although the range of the exposure temperature depends on the liquid crystal temperature range of the liquid crystal compound, for example, in the case of a material having a liquid crystal phase at −20 ° C. to 90 ° C., it is preferably 20 ° C. or lower than the isotropic phase transition temperature, More preferably, exposure is performed in a relatively low temperature range of about 20 ° C. to 40 ° C. near room temperature. The ultraviolet intensity at the second active energy ray irradiation, to the coating layer, preferably ^{3mW / cm 2 ~150mW / cm 2} , more preferably ^{5mW / cm 2 ~100mW / cm 2} , more preferably 10 mW / cm ^{2 to} 50 mW / cm ² . By performing pattern exposure and whole-surface exposure under such irradiation conditions, it is possible to form light control layers and partition walls having different component ratios from the same liquid crystal composition. The ultraviolet irradiation may be performed continuously or intermittently as long as a desired integrated dose is obtained. As the light source, for example, a high-pressure mercury lamp, a low-pressure mercury lamp, a metal halide lamp, a UV-LED, or the like can be used.

  In another embodiment, the method for manufacturing a light control device of the present invention includes printing a material containing the second polymer in a desired pattern on one substrate, and irradiating with active energy and / or heating as necessary. Forming a partition, coating the liquid crystal composition on the substrate on which the partition is formed, forming a coating layer, laminating the other substrate on the coating layer, and a pair of substrates and the substrate Producing a laminate having a coating layer and a partition sandwiched between substrates, and forming a light control layer by irradiating active energy rays on the entire surface of the laminate.

  The printing can be performed by a method such as nanoimprinting or screen printing.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited by these Examples. Further, the following “parts” or “%” means “parts by weight” or “% by weight” unless otherwise specified.

≪Measurement method of drive voltage≫
An AC voltage was applied to the light control device while boosting it using EC750SA manufactured by NF Circuit Design Block, and the voltage at the time when the haze reached the upper limit was read and evaluated as a drive voltage. In addition, since the polarization dependence by liquid crystal orientation generate | occur | produces when it does not have chirality, it injects through a polarizing plate and measures.
≪Measuring method of linear expansion coefficient≫
The linear expansion coefficient was measured by a thermomechanical analyzer (TMA).
≪Measurement method of polymer content≫
The polymer content was calculated by image analysis from an electron microscope image of the partition wall cross section. Specifically, the liquid crystal phase in the cross section was removed, and the ratio of the area occupied by the polymer portion in the 100 μm square field of view was defined as the polymer content. The polymer content in the light control layer was calculated from a value obtained by removing the polymer amount contained in the partition walls from the total polymer amount contained in the partition walls and the light control layer.
≪Measurement method of haze≫
It measured with the haze meter "HGM-2DP" by Suga Test Instruments Co., Ltd.

[Example 1]
A polyimide film (JSR Co., “Optomer AL1254”) is applied to the electrode surface of a PET film (thickness 100 μm) having a transparent electrode (ITO film) of 100Ω / □ on one side, and heated at 90 ° C. for 10 minutes. Thereafter, the film was baked at 120 ° C. for 90 minutes, and rubbed in a uniaxial direction to form a parallel alignment film. As a result, a substrate A having a configuration of [alignment film / transparent electrode / PET film] was obtained. The obtained substrate A had a linear expansion coefficient of 30 ppm / ° C.
80 parts of a liquid crystal compound (manufactured by HCCH, “854600-00”) and 20 parts of a crosslinked liquid crystal monomer (manufactured by BASF, “LC242”) were mixed. 1 part of a polymerization initiator (“Irgacure TPO” manufactured by BASF Corp.) was added to LC242 to the obtained mixture, heated to an isotropic phase, and stirred to obtain a liquid crystal composition.
The obtained liquid crystal composition was applied to the surface of the alignment film of the substrate with a thickness of 20 μm. Next, another substrate A was bonded onto the coating layer so that the alignment film was in contact with the coating layer, and a laminate having a configuration of [substrate A / coating layer / substrate A] was produced. Subsequently, the laminated body was irradiated with ultraviolet rays at room temperature through a photomask having a pattern (planar lattice-like pattern) in which 150 μm square light shielding portions were arranged in a matrix at intervals of 15 μm. Specifically, irradiation was performed continuously for 10 minutes at an illuminance of 30 mW / cm ² with an LED light source having a center wavelength of 365 nm. As a result, the liquid crystal monomer was polymerized in the ultraviolet irradiation part to form a liquid crystal polymer, and a continuous partition wall corresponding to the pattern was formed. Next, the unreacted liquid crystal monomer in the coating layer was polymerized by irradiating continuously for 5 minutes at an illuminance of 10 mW / cm ² using the same light source without passing through a photomask. As a result, a composite (light control layer) in which liquid crystal compounds were phase-separated or dispersed in a network of liquid crystal polymers was formed.
As described above, a reverse mode type light control film was obtained.

[Example 2]
The liquid crystal composition has a blending amount of 90 parts, a liquid crystal monomer content of 10 parts, and a pattern in which 100 μm square light-shielding portions are arranged in a matrix at intervals of 10 μm. A reverse mode type light control film was obtained in the same manner as in Example 1 except that a photomask was used.

[Comparative Example 1]
Reverse mode was performed in the same manner as in Example 1 except that the amount of the liquid crystal compound in the liquid crystal composition was 70 parts, the amount of the liquid crystal monomer was 30 parts, and no photomask was used. A mold light control film was obtained.

[Comparative Example 2]
Reverse mode was performed in the same manner as in Example 1 except that the blending amount of the liquid crystal compound in the liquid crystal composition was 95 parts, the blending amount of the liquid crystal monomer was 5 parts, and no photomask was used. A mold light control film was obtained.

[Comparative Example 3]
The liquid crystal composition has a blending amount of 50 parts, a liquid crystal monomer blending amount of 50 parts, and a pattern in which 100 μm square light-shielding portions are arranged in a matrix at intervals of 20 μm. A reverse mode type light control film was obtained in the same manner as in Example 1 except that a photomask was used.

The obtained light control film was subjected to bending test 1. The test results are shown in Table 1 together with the haze value before bending and the driving voltage.
<Bending test 1>
The light control film was bent by pressing against a cylindrical rod having a diameter of 10 cm, and then returned to a flat state. In addition to observing the appearance in the bent state, the amount of change in the haze value of the light control film before and after bending (no voltage applied) (the absolute value of the difference between the haze value before bending and the haze value after bending) Asked.

  As shown in Table 1, in the light control films of Examples 1 and 2, the partition walls suitably functioned in the bending test. As a result, white turbidity did not occur and the change in haze was small. Furthermore, good display characteristics were exhibited at an appropriate driving voltage. On the other hand, in the light control film of Comparative Example 1, since the polymer content in the light control layer is large and there is no partition wall, the cloudiness is temporarily generated in the bending test, and the initial haze is high. The drive voltage also increased. In the light control film of Comparative Example 2, since the polymer content in the light control layer was small and there were no partition walls, white turbidity occurred in the bending test, and the amount of change in haze increased. In the light control film of Comparative Example 3, the partition walls suitably functioned in the bending test. As a result, white turbidity did not occur, but because the polymer content in the light control layer was large, the initial haze was high, and the drive voltage was also high. Rose.

[Example 3]
A coating film of polyimide (manufactured by JSR, “Optomer AL3046”) is formed on the electrode surface of a roll-shaped PET film (thickness: 188 μm) having a transparent electrode (ITO film) on one side, and rubbed in a uniaxial direction. Thus, a parallel alignment film was formed. This obtained the board | substrate B which has the structure of [alignment film / transparent electrode / PET film]. The obtained substrate B had a linear expansion coefficient of 30 ppm / ° C.
80 parts of a liquid crystal compound (manufactured by HCCH, “854600-00”) and 20 parts of a polymerization type liquid crystal monomer (manufactured by BASF, “LC242”) were mixed. To the obtained mixture, 1 part of a polymerization initiator (manufactured by BASF, “Irgacure TPO”) was added to LC242, heated to an isotropic phase, and stirred to obtain a liquid crystal composition.
The obtained liquid crystal composition was applied to the surface of the alignment film of the substrate with a thickness of 20 μm. Next, another substrate B was bonded onto the coating layer so that the alignment film was in contact with the coating layer, and a laminate having the configuration of [substrate B / coating layer / substrate B] was produced. Subsequently, the laminate was irradiated with ultraviolet rays at room temperature through a photomask having a pattern in which light-shielding portions of 100 μm square were arranged in a matrix at intervals of 10 μm. Specifically, it was continuously irradiated for 5 minutes at an illuminance of 20 mW / cm ² with an LED light source having a center wavelength at 365 nm. As a result, the liquid crystal monomer was polymerized in the ultraviolet irradiation part to form a liquid crystal polymer, and a continuous partition wall corresponding to the pattern was formed. Next, the unreacted liquid crystal monomer in the coating layer was polymerized by continuously irradiating with an illuminance of 10 mW / cm ² for 5 minutes without using a photomask. As a result, a composite (light control layer) in which liquid crystal compounds were phase-separated or dispersed in a network of liquid crystal polymers was formed.
As described above, a reverse mode type light control film was obtained.

[Comparative Example 4]
A reverse mode type light control film was obtained in the same manner as in Example 3 except that no photomask was used.

[Comparative Example 5]
97 parts of a liquid crystal compound (manufactured by HCCH, “854600-00”) and 3 parts of a polymerization type liquid crystal monomer (manufactured by BASF, “LC242”) were mixed. 1 part of a polymerization initiator (“Irgacure TPO” manufactured by BASF Corp.) was added to LC242 to the obtained mixture, heated to an isotropic phase, and stirred to obtain a liquid crystal composition.
A reverse mode type light control film was obtained in the same manner as in Example 3 except that the liquid crystal composition prepared as described above was used.

The obtained light control film was subjected to bending test 2. The test results are shown in Table 2 together with the driving voltage.
<Bending test 2>
The light control film was bent by pressing against a cylindrical rod having a diameter of 10 cm, and then returned to a flat state. The appearance of the film after returning to the bent state and the flat state was observed.

  As shown in Table 2, the dimming device of Example 3 did not generate white turbidity even after the bent state and the bending were released as a result of the partition walls functioning properly. On the other hand, in the light control device of Comparative Example 4 in which no partition wall was formed, the liquid crystal compound leaked from the end portion by bending. In addition, after the bending was released, white turbidity occurred in the light control layer in the transmission mode, and peeling occurred at the end. In Comparative Example 5 in which the content of the liquid crystal polymer was small, the partition walls did not function sufficiently, and the liquid crystal compound oozed out at the end due to bending. In addition, after the bending was released, white turbidity occurred in the light control layer in the transmission mode.

  The light control device of this invention is used suitably in field | areas, such as a film for window glasses, an image display apparatus.

DESCRIPTION OF SYMBOLS 100 Light control device 10 Board | substrate 20 Partition 30 Light control layer 32 Section

Claims (8)

A pair of substrates, a light control layer that is sandwiched between the substrates and includes a first polymer and a liquid crystal compound, and a partition wall that includes a continuous structure that partitions the light control layer into a plurality of sections, and includes a second polymer A flexible dimming device comprising:
The content of the first polymer in the light control layer is 20% by weight or less,
The content of the second polymer in the partition walls is 60% by weight or more,
The partition spacing is 10 mm or less,
The width of the partition wall is 1% to 100% with respect to the length of one side of the section.
Dimming device.   The light control device according to claim 1, wherein a ratio of an area of the light control layer to a total area of the light control layer and the partition in a plan view is 60% or more.   The light control device according to claim 1, wherein the first polymer and the second polymer are polymerization reaction products of the same monomer component.   The light control device in any one of Claim 1 to 3 whose linear expansion coefficient of the said board | substrate is 100 ppm or less.   The light control device in any one of Claim 1 to 4 with which the hard-coat layer is provided in the opposite side to the said light control layer of at least one said board | substrate.   The light control device in any one of Claim 1 to 5 with which the protective layer is provided in the opposite side to the said light control layer of at least one said board | substrate.   The light control device according to claim 1, wherein the first polymer and the second polymer include a liquid crystal polymer.   The light control device according to any one of claims 1 to 7, wherein a change in haze value in bending with a curvature radius of 100 mm is 1% or less.