JP2008112011A - Layered body including particle dispersion layer, method for manufacturing the same, and optical modulation element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a layered body in which the surface flatness of a particle dispersion layer having particles dispersed and placed therein is improved, and to provide a method for manufacturing the layered body, and an optical modulation element. <P>SOLUTION: The layered body comprises a particle dispersion layer 8 containing particles 2 dispersed and placed in a first material 4 that changes from a gel state to a sol state with temperature rise and a cover layer 6 containing a second material that changes from a sol state to a gel state with temperature rise, the particle dispersion layer 8 in a sol state being in contact with the cover layer 6 in a gel state. The method for manufacturing the layered body includes steps of raising the temperature of a particle dispersion layer 8 containing a particle dispersion liquid prepared by dispersing particles 2 in a first material 4 that changes from a gel state to a sol state with temperature rise and a cover layer 6 containing a coating liquid of the cover layer comprising a second material that changes from a sol state to a gel state with temperature rise, until the coating liquid of the cover layer changes into a gel state and the particle dispersion liquid changes into a sol state, and drying and curing the layers. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a laminate including a particle dispersion layer, a method for manufacturing the same, and a light modulation element.

  Various convenient rewritable marking technologies have been researched. As one of the directions, the light modulation element using cholesteric liquid crystal has a memory property that can hold a display with no power source, and a polarizing plate. In recent years, it has attracted attention because it has features such as a bright display because it is not used and the ability to perform color display without using a color filter.

  The planar phase shown by cholesteric liquid crystal (chiral nematic liquid crystal) divides light incident parallel to the helical axis into right-handed rotation and left-handed rotation, Bragg-reflects circularly polarized light components that match the twist direction of the helix, and reflects the remaining light. Causes a selective reflection phenomenon to be transmitted. The central wavelength λ and the reflection wavelength width Δλ of the reflected light are λ = n · p and Δλ =, where p is the helical pitch, n is the average refractive index in the plane orthogonal to the helical axis, and Δn is the birefringence. The light reflected by the cholesteric liquid crystal layer in the planar phase expressed by Δn · p exhibits a bright color depending on the helical pitch.

  As shown in FIG. 12A, the cholesteric liquid crystal having positive dielectric anisotropy has a planar phase in which the helical axis is perpendicular to the cell surface and causes the above-described selective reflection phenomenon with respect to incident light. As shown in FIG. 12 (B), the helical axis is substantially parallel to the cell surface and allows the incident light to pass through while being slightly scattered, and as shown in FIG. The director shows three states: a homeotropic phase in which the director is directed in the direction of the electric field and almost completely transmits the incident light.

  Among the above three states, the planar phase and the focal conic phase can exist bistable without an electric field. Therefore, the phase state of the cholesteric liquid crystal is not uniquely determined with respect to the electric field strength applied to the liquid crystal layer. When the planar phase is in the initial state, the planar phase and the focal conic phase are increased as the electric field strength increases. When the focal conic phase is in the initial state, the focal conic phase and the homeotropic phase change in this order as the electric field strength increases.

On the other hand, when the electric field strength applied to the liquid crystal layer is suddenly reduced to zero, the planar phase and the focal conic phase are maintained as they are, and the homeotropic phase is changed to the planar phase.
Therefore, the cholesteric liquid crystal layer immediately after the pulse signal is applied exhibits a switching behavior as shown in FIG. 13, and when the applied pulse signal voltage is equal to or higher than Vfh, the selective reflection is changed from the homeotropic phase to the planar phase. When it is between Vpf and Vfh, it becomes a transmission state due to the focal conic phase, and when it is equal to or lower than Vpf, the state before the pulse signal application is continued, that is, a selective reflection state due to the planar phase or a transmission state due to the focal conic phase. Become.

  In FIG. 13, the vertical axis represents the normalized light reflectance, and the light reflectance is normalized with the maximum light reflectance being 100 and the minimum light reflectance being 0. In addition, since there are transition regions between the states of the planar phase, the focal conic phase, and the homeotropic phase, when the normalized light reflectance is 50 or more, the selective reflection state, and the normalized light reflectance is less than 50. The case is defined as a transmission state, the threshold voltage of the phase change between the planar phase and the focal conic phase is Vpf, and the threshold voltage of the phase change between the focal conic phase and the homeotropic phase is Vfh.

  The cholesteric liquid crystal display element has a PDLC (Polymer Dispersed Liquid Crystal) structure in which cholesteric liquid crystal is dispersed in a polymer binder in the form of a drop in addition to a structure in which liquid crystal is sealed as a continuous phase between a pair of display substrates, and a polymer binder. A PDMLC (Polymer Dispersed Liquid Crystal Crystal) structure in which microencapsulated cholesteric liquid crystal is dispersed can be formed (for example, see Patent Documents 1 to 3).

  When the PDLC structure or the PDMLC structure is used, the fluidity of the liquid crystal is suppressed, so that the image disturbance due to bending and pressure is reduced, and a flexible medium can be realized. Further, a color display can be performed by directly laminating a plurality of cholesteric liquid crystal layers, or a display element which can be laminated with a photoconductive layer to address an image with an optical signal. Further, since the display layer can be formed using a thick film printing technique, there is an advantage that the manufacturing method is simplified and the cost is reduced.

Conventionally, many light modulation elements using the technology have been proposed (see, for example, Patent Document 4).
The optically addressed spatial light modulator according to this technology uses this cholesteric liquid crystal bistable phenomenon to switch between (A) the selective reflection state by the planar phase and (B) the transmission state by the focal conic phase. Accordingly, monochrome display of various hues having memory characteristics without an electric field or color display having memory characteristics without an electric field is performed.

FIG. 14 is a schematic diagram schematically showing a state in which an exposure apparatus performs image writing on a general light modulation element according to the technology. As shown in FIG. 14, the light modulation element according to the technique has a display layer that is a liquid crystal layer and an OPC layer that is a photoconductor layer between a pair of transparent electrodes (a light shielding layer (not shown) if necessary). Are stacked) and are sandwiched between a pair of substrates. A desired recorded image can be written by exposing the surface of the OPC layer sidewise with an exposure device while applying a predetermined bias voltage to both transparent electrodes.
The light modulation element according to the technology can form a full-color image by laminating three colors of RGB in which a unit in which a display layer and a photoconductive layer are sandwiched between electrode layers is laminated.

  The light modulation element according to the technique is formed by laminating layers including a light modulation layer in which particles such as liquid crystal drops or liquid crystal microcapsules are dispersedly arranged. This light modulation layer is generally formed by applying and curing a polymer binder containing liquid crystal drops or liquid crystal microcapsules. When the liquid crystal drops or the liquid crystal microcapsules are arranged densely in a single layer, the variation in the abundance ratio between the polymer binder and the liquid crystal drops or the liquid crystal microcapsules in the element cross-sectional direction is reduced, and the surface flatness is increased. For this reason, the uniformity of the drive voltage according to the position in the surface when a voltage is applied from above and below the layer is improved. In addition, since the interface between the polymer binder and the liquid crystal drop or the liquid crystal microcapsule that causes unnecessary light scattering is reduced, both flexibility and display quality can be achieved.

  Patent Document 5 by the present inventors discloses a liquid crystal display element in which a liquid crystal drop or liquid crystal microcapsule is dispersed in a solution containing gelatin and a solvent, and the liquid crystal drop or liquid crystal microcapsule is applied to the liquid crystal display element. A manufacturing method is disclosed. This manufacturing method makes it possible to form a display layer in which liquid crystal drops or liquid crystal microcapsules in a coating solution are arranged in a single layer and densely and the surface is flat. This is because colloidal solutions that produce a sol-gel change such as a solution containing gelatin and a solvent maintain a soft and highly fluid sol state inside the membrane with a large amount of residual water during the decreasing rate drying period at the end of drying. Since a part of the reduced film surface starts to gradually change to a hard gel state, it is assumed that a mechanism in which the liquid crystal drop or the liquid crystal microcapsule is pushed into the film is working.

  The prior art has been described above centering on the light modulation element having the display layer including the liquid crystal drop or the liquid crystal microcapsule. However, the laminate including the particle dispersion layer in which some particles are dispersed is various in addition to the light modulation element. What is desired when forming the particle-dispersed layer is the same or similar.

Japanese Patent Publication No. 7-009512 Japanese Patent Laid-Open No. 9-236791 Japanese Patent No. 3178530 JP 11-237644 A JP 2005-258310 A

  It is an object of the present invention to provide a laminate in which the surface flatness of a particle dispersion layer in which particles are dispersed and arranged, a method for producing the laminate, and a light modulation element are provided.

The above-mentioned subject is achieved by the present invention shown in the following <1> to <19>.
<1> Particle dispersion layer in which particles are dispersed and arranged in a first material that changes from a gel state to a sol state as the temperature rises, and a change from the sol state to the gel state as the temperature rises And a coating layer containing the second material, wherein the particle dispersion layer in a sol state and the coating layer in a gel state are stacked in contact with each other.

  <2> The laminate according to <1>, wherein the particle dispersion layer in a sol state and the coating layer in a gel state are dried.

<3> Maximum temperature T _{1 at} which the first material maintains a gel state in a state containing a solvent is a temperature equal to or higher than a temperature T _{2 at} which the second material changes to a gel state (T ₁ ≧ T ₂ ). The laminate according to <1>, which is

  <4> The laminate according to <1>, wherein the particles are dispersed and arranged in a single-layer state in the particle dispersion layer.

<5> The laminate according to <3>, wherein the particle diameter D of the particles and the layer thickness t of the particle dispersion layer satisfy the following relational expression (A).
0.5t ≦ D ≦ 2t ... Relational expression (A)

<6> A particle dispersion layer including a particle dispersion in which particles are dispersed in a first material that changes from a gel state to a sol state as the temperature rises, and a first state that changes from the sol state to the gel state as the temperature rises. A heating step of heating the coating layer containing a coating layer coating solution made of the material 2 in a state where the coating layer coating solution is in a gel state and the particle dispersion is overlaid in a sol state;
The temperature is raised in a temperature raising step, the coating layer coating solution is in a gel state and the temperature at which the particle dispersion becomes a sol state is maintained, and a drying and curing step of drying and curing both the coated liquids;
The manufacturing method of the laminated body characterized by including.

<7> Performed prior to the temperature raising step.
A particle dispersion applying step of applying a particle dispersion in which particles are dispersed in the first material to a substrate surface at a temperature at which the particle dispersion becomes a sol;
A cooling step of cooling to a temperature at which the particle dispersion applied in the particle dispersion application step becomes a gel state;
Coating that coats the coating liquid comprising the second material on the particle dispersion that has been in a gel state in the cooling step at a temperature at which the coating liquid is in a sol state and the particle dispersion liquid is in a gel state. A layer coating process;
The manufacturing method of the laminated body as described in <6> characterized by including.

<8> The maximum temperature T _{1 at} which the first material maintains a gel state is equal to or higher than the temperature T _{2 at} which the second material changes to a gel state (T ₁ ≧ T ₂ ). The manufacturing method of the laminated body as described in <6>.

  <9> The method for producing a laminate according to <6>, wherein the second material is a solution containing cellulose or a derivative thereof and a solvent.

  <10> The method for producing a laminate according to <6>, wherein the first material is a solution containing gelatin or a derivative thereof and a solvent.

  <11> In the particle dispersion coating step, a particle dispersion liquid in which the concentration of the particles is adjusted so that the particles are dispersed and arranged in a single layer state in the particle dispersion layer of the laminate after production. The method for producing a laminate according to <7>, wherein the laminate is used.

  <12> Light in which particles of a light modulation substance or a microencapsulated light modulation substance are dispersedly arranged in at least a first material that changes from a gel state to a sol state as the temperature rises between a pair of electrodes A modulation layer, and a protective layer containing a second material that changes from a sol state to a gel state as the temperature rises, and the light modulation layer in the sol state and the protective layer in the gel state are stacked in contact with each other A light modulation element characterized by comprising:

  <13> The light modulation element according to <12>, wherein the light modulation layer in a sol state and the protective layer in a gel state are dried.

  <14> The light modulation element according to <12>, wherein the light modulation material is a cholesteric liquid crystal.

  <15> The light modulation element according to <12>, wherein the protective layer is made of cellulose or a derivative thereof.

  <16> The light modulation element according to <12>, wherein the light modulation layer is formed by dispersing and disposing the particles in gelatin or a derivative thereof.

  <17> The light modulation element according to <10>, wherein the particles have a polyhedral shape.

  <18> The light modulation element according to <12>, wherein the particles are densely dispersed in a single layer state in the light modulation layer.

<19> The light modulation element according to <18>, wherein the particle diameter D of the particles and the layer thickness t of the light modulation layer satisfy the following relational expression (A).
0.5t ≦ D ≦ 2t ... Relational expression (A)

  The invention according to <1> includes a particle-dispersed layer in which particles are dispersed and arranged in a first material that changes from a gel state to a sol state as the temperature rises, and the sol as the temperature rises. A coating layer containing a second material that changes from a state to a gel state, and the particle dispersion layer in a sol state and the coating layer in a gel state are laminated in contact with each other. By pressing the particles of the particle dispersion layer, it is possible to provide a laminate that can improve flatness.

  The invention according to <2> can provide a laminate in which the flatness of the particle dispersion layer is improved.

  In the invention according to <3>, since there is a temperature region in which both the particle dispersion layer and the coating layer are gelled, either layer can be brought into a gelled state through temperature change during film formation. Mixing due to dissolution between layers is suppressed.

  The invention according to <4> provides a laminate having a uniform particle dispersion layer compared to the case of only the particle dispersion layer because the particles are dispersed and arranged in a single layer state in the particle dispersion layer. can do.

  In the invention according to <5>, since the particle diameter D of the particles is appropriately small with respect to the layer thickness t of the particle dispersion layer, there is no concern about a multi-layer structure, and the particles are compared with the case of only the particle dispersion layer. It is possible to provide a laminate in which the particles are dispersed and arranged in a single layer and dense state in the dispersion layer.

  In the invention according to <6>, in the drying and curing step, since the drying and curing proceeds in a state where the film of the coating layer coating solution in a gel state is covered as the upper layer of the sol-state particle dispersion, the coating layer is made of particles. The particles in the dispersion are pushed in, and the surface of the particle dispersion layer is flattened as compared with the case of only the particle dispersion layer.

  In the invention according to <7>, after the particle dispersion applied in the particle dispersion application step is made into a gel state in the cooling step, the coating layer coating solution in a sol state is applied in the coating layer application step. The particle dispersion liquid in both liquids applied in stages is in a gel state. After that, when the temperature is raised in the temperature raising step to dry and cure, the coating layer coating solution in both of the two solutions that have been applied is in a gel state, and this state is maintained while the drying and curing step is maintained. The two liquids are dried and cured.

  Accordingly, in the process after the both liquids are applied, since at least one of the two liquids is in a gel state or a state corresponding thereto, mixing due to dissolution between the two layers is suppressed through the layer forming process. The In addition, even when the same solvent is used as the solvent of both liquids, the effect of suppressing mixing due to dissolution between the two layers is manifested, and the particle dispersion liquid to be applied is first insolubilized by chemical crosslinking before coating. Since it is not necessary to add a cross-linking agent for laminating the layer coating liquid, there is no fear of curing with the cross-linking agent, and the pot life of the particle dispersion to be used can be extended.

  In the invention according to <8>, since there is a temperature region in which both the particle dispersion layer and the coating layer are gelated even at the time of a temperature change in the temperature raising step, any one of the layers is always gelled throughout the manufacturing process. It can be in a state, and mixing due to dissolution between the two layers is further suppressed.

  In the invention according to <9>, since a solution that contains water-soluble and easily available general cellulose or a derivative thereof and a solvent is used as the second material, a laminate can be produced safely and at low cost. Can do.

  In the invention according to <10>, a laminated body can be manufactured safely and at low cost because the first material is a water-soluble and easily available solution containing gelatin and a solvent.

  Since the invention concerning <11> uses the particle dispersion liquid in which the concentration of the particles is appropriately adjusted in the particle dispersion application step, a laminate having a surface-uniform particle dispersion layer can be produced.

  In the invention according to <12>, the light modulation layer is formed by dispersing particles made of a light modulation substance or a microencapsulated light modulation substance in a first material that changes from a gel state to a sol state as the temperature rises. A protective layer adjacent thereto is formed of a second material material that changes from a sol state to a gel state as the temperature rises, and the light modulation layer in the sol state and the protective layer in the gel state are laminated in contact with each other. Therefore, when the temperature rises, the protective layer presses the light-modulating substance or microcapsule of the light-modulating layer, so that the light-modulating element with improved flatness of the light-modulating layer compared to the case of only the particle-dispersed layer can be obtained. Can be provided.

  The invention according to <13> provides a light modulation element in which variation in display performance in the display surface is reduced as compared with the case of using only the light modulation layer, since drying is performed while the flatness of the light modulation layer is enhanced. can do.

  The invention according to <14> can provide a light modulation element in which microcapsules containing a cholesteric liquid crystal are arranged with high uniformity, and variation in optical characteristics is small.

  In the invention according to <15>, since the water-soluble and easily available cellulose or a derivative thereof is used as the material for the protective layer, the light modulation element can be provided safely and at low cost.

  The invention according to <16> uses a water-soluble and readily available gelatin or a derivative thereof as a material for the light modulation layer, and therefore can provide the light modulation element safely and at low cost.

  In the invention according to <17>, since the particle has a polyhedral shape, the inner surface of the particle is in a horizontal or vertical direction with respect to the substrate, and the disorder of liquid crystal orientation seen in the spherical particle can be suppressed. As compared with the above, it is possible to provide a light modulation element having a wide reflection area and bright.

  In the invention according to <18>, light modulation material or microencapsulated light modulation material particles are densely dispersed and arranged in a single layer in the light modulation layer. It is possible to provide a light modulation element in which a layer is formed and which is excellent in precise image reproducibility.

  In the invention according to <19>, since the particle diameter D of the particles is appropriately small with respect to the layer thickness t of the particle dispersion layer, there is no concern about a multi-layer structure, and compared with the case of only a light modulation layer, To provide an even more excellent light modulation element with fine image reproducibility, in which particles of a light modulation material or a microencapsulated light modulation material are dispersed and arranged in a single layer and denser in a light modulation layer. Can do.

Hereinafter, the laminated body of the present invention, the manufacturing method thereof, and the light modulation element will be sequentially described in detail.
[Laminate]
In the laminate of the present invention, particles are dispersedly arranged in a first material (hereinafter sometimes referred to as “low temperature gelling material”) that changes from a gel state to a sol state as the temperature rises, and the material is A hardened particle dispersion layer, and a coating layer containing a second material that changes from a sol state to a gel state as the temperature rises (hereinafter sometimes referred to as “high temperature gelling material”), The particle dispersion layer in a state and the coating layer in a gel state are laminated in contact with each other.

FIG. 1 shows a cross-sectional view of a laminate which is an exemplary embodiment of the present invention. In the laminated body of this example, a particle dispersion layer 8 in which particles 2 are dispersed and arranged in a matrix 4 and a coating layer 6 are laminated on the surface of a substrate 10.
As the laminate of the present invention, various layers other than these three layers including the substrate 10 may be formed. Even if the substrate 10 is not provided, the particle dispersion layer 8 and the coating layer 6 may be laminated not on the substrate 10 or on some other layer formed in advance on the substrate 10. That is, in the laminate of two or more layers, if the layers corresponding to the particle dispersion layer 8 and the coating layer 6 are arranged next to each other in the layer, other requirements of the present invention are provided. The conditions are included in the category of the laminate of the present invention.

  Examples of the particles 2 to be dispersed and arranged include various materials depending on the use of the laminate. For example, when the laminated body is the light modulation element of the present invention described later, “particles made of a light modulation material or a microencapsulated light modulation material” may be used as the particles 2. In addition, substances having functions such as colorability, conductivity, luminescence, adhesiveness, and chemical reactivity can be used as the particles 2 in accordance with various applications.

  The matrix 4 is formed by curing a low-temperature gelling material (first material). The low-temperature gelling material refers to a colloidal solution that changes from a gel state to a sol state with an increase in temperature, and various colloidal particles and solvents can be used. As the colloidal particles constituting the low-temperature gelling material, natural polymer, synthetic polymer, or semi-synthetic polymer can be used. Gelatin, agar, cellulose, carrageenan, alginic acid, xanthan gum, pectin, seed gum, fur celerane, Examples of polymers such as curdlan, polyvinyl alcohol, polyacrylonitrile, polyethylene oxide, and derivatives thereof, or those mixed with a polymer having no low-temperature gelation property as a low-temperature gelling agent, As physical properties, those having high jelly strength and low sol viscosity are preferred.

  When gelatin is used as the colloidal particles constituting the low-temperature gelling material, there are few high molecular weight β chains and γ chains that are α chain multimers, and low molecular weight components in which the α chain main chain is cut off in the middle. Those having a large α chain remaining amount are suitable. A gelatin material produced by acid treatment of bovine bone is preferable because it satisfies this condition, and particularly has high jelly strength and low sol viscosity. Moreover, the 1st extract extracted first when hydrolyzing the collagen of a raw material is good. If necessary, ionic components remaining in the gelatin may be removed using a known method such as an ion exchange resin.

  As the solvent used in the colloidal solution constituting the low-temperature gelling material, a solvent that dissolves the colloidal particles such as gelatin and does not dissolve the particles to be dispersed is used. For example, when liquid crystal microcapsules described later are used as the particles to be dispersed, those that do not dissolve at least the polymer shell of the microcapsules are used. Examples of the solvent used in the present invention include water, a mixture of water and alcohols such as methanol, ethanol and glycol.

  The covering layer 6 is made of a high-temperature gelling material (second material). The high-temperature gelling material refers to a colloidal solution that changes from a sol state to a gel state as the temperature rises, and includes various colloidal particles and solvents. As the colloidal particles constituting the high-temperature gelling material, natural polymer, synthetic polymer, or semi-synthetic polymer can be used. Cellulose, protein, curdlan, polyvinyl acetal, polyvinyl alkyl ether, poly Examples thereof include polymers such as ether polyols and polyacrylamides and derivatives thereof, or those mixed with polymers having no high-temperature gelation property as high-temperature gelling agents. Further, since the coating layer 6 does not need to return to the sol state again after changing from the low temperature sol state to the high temperature gel state, the heat-curing polymer such as melamine-formalin resin, or the functional group such as gelatin. It is also possible to use a colloidal solution in which the sol-gel state is irreversible, such as a polymer having an aldehyde added with a crosslinking agent that reacts by heating such as aldehyde. As physical properties of the polymer solution, those having high jelly strength and low sol viscosity are preferred.

  When a cellulose derivative is used as the colloidal particles constituting the high-temperature gelling material, those obtained by substituting some of the hydrogen atoms of the hydroxyl groups of cellulose with methyl groups, hydroxypropyl groups, hydroxyethyl groups, and the like are suitable. In particular, a material substituted with a methyl group is preferable because of particularly high jelly strength.

As the solvent used for the colloidal solution constituting the high-temperature gelling material, a solvent that dissolves the polymer such as a cellulose derivative is used. Examples of the solvent used in the present invention include water, a mixture of water and alcohols such as methanol, ethanol and glycol.
As these low-temperature gelling materials and high-temperature gelling materials, in addition to the above essential components, surfactants, various dispersants, thickeners, wettability improvers, antifoaming agents, drying rate modifiers, and other laminates Various additives according to the application can be added.

  The particle-dispersed layer 8 and the coating layer 6 are formed by curing a low-temperature gelling material and a high-temperature gelling material, respectively. For curing, drying and curing by heating is generally employed. By drying and curing, the low-temperature gelling material and the solvent in the high-temperature gelling material are volatilized, and the colloidal particles contained therein are aggregated to form respective layers.

Since the low temperature gelling material and the high temperature gelling material are preferably in the form of a gel when the temperature changes during production, the maximum temperature at which the low temperature gelling material can maintain a gel state ( It is desirable that the maximum gelation temperature T ₁ is a temperature (T ₁ ≧ T ₂ ) equal to or higher than the temperature at which the high-temperature gelling material changes to a gel state (minimum gelation temperature) T ₂ . A more preferable relationship between T ₁ and T ₂ will be described later.

It should be noted that both the “temperature” at the maximum gelation temperature T _{1 at which} the low-temperature gellable material can maintain a gel state and the minimum gelation temperature T _{2 at which the} high-temperature gellable material changes to a gel state are: Each material (colloidal solution) means a critical temperature at which the normalized viscosity becomes 70 or higher when the saturated viscosity in the gel state is 100 and the saturated viscosity in the sol state is 0.
The critical temperature at which the normalized viscosity is 30 or less is defined as “solation temperature”, the temperature at which the high-temperature gelling material changes to a sol state is the maximum sollation temperature T ₃ , and the low-temperature gelling material is sol The temperature at which the state can be maintained is defined as the lowest solubilization temperature T ₄ .

  Similarly, in the present invention, the standard based on the viscosity is applied to the cases of “gelling” and “being in a gel state”, and “gelled” when the normalized viscosity is 70 or more. It can be expressed as “gel state”. On the other hand, in the present invention, “solate” and “become sol state” mean the state in which the above normalized viscosity is 30 or less.

  As shown in FIG. 1, it is preferable that the particles 2 are dispersed and arranged in the particle dispersion layer 8 in a single layer state depending on the use of the laminated body. It may be distributed.

  In the laminate of the present invention, the particle size of the particles 2 and the thickness of the particle dispersion layer 8 and the coating layer 6 are not particularly limited, and may be arbitrarily selected depending on the use of the laminate. Specifically, the particle diameter of the particles 2 is appropriately selected from the range of about 100 nm to 1 mm, the thickness of the particle dispersion layer 8 is in the range of about 50 nm to 2 mm, and the thickness of the coating layer 6 is appropriately selected from the range of about 100 nm to 1 mm. .

In order to disperse and disperse the particles 2 in a single layer state in the particle dispersion layer 8 in a dense manner, the particle diameter D of the particles 2 and the layer thickness t of the particle dispersion layer 8 (see FIG. 1) are as follows: It is desirable to satisfy (A).
0.5t ≦ D ≦ 2t ... Relational expression (A)
In this relational expression (A), the left side is more preferably 0.7 t, and further preferably 0.8 t. Further, the right side is more preferably 1.3t, and further preferably 1.2t.

The particle diameter D referred to here means the number average diameter (or equivalent sphere diameter if not a sphere), for example, an image of 2,000 target particles arbitrarily sampled and observed with a microscope. Is a value obtained by measuring each particle size by digital processing and averaging the number. Alternatively, a light-shielding type that measures the particle size by the amount of change in transmitted light due to the passage of particles or a light-scattering type particle size measuring device that specifies the particle size distribution by measuring the light scattering intensity that changes depending on the particle size may be used. it can.
According to the method for producing a laminate of the present invention, which will be described later, as shown in FIG. 1, it is possible to produce a laminate in which particles 2 are in a single layer state and are densely dispersed in a particle dispersion layer 8. it can.

[Manufacturing method of laminate]
The laminate production method of the present invention (hereinafter sometimes simply referred to as “the production method of the present invention”) includes (1) a particle dispersion coating step, (2) a cooling step, (3) a coating layer coating step, It consists of five steps: (4) temperature rising step and (5) dry curing step. However, (2) the cooling step is not an essential step as will be described later.

FIG. 2 is a list showing the production process of the laminate by the production method of the present invention, taking the laminate shown in FIG. 1 as an example, and the appearance (cross section) and the state of each layer are schematically shown in the order of steps. ing. Hereafter, it demonstrates in detail for every process using FIG.
In the following description of the manufacturing method, the case of forming a light modulation layer and a protective layer in the light modulation element of the present invention described later will be referred to as appropriate.

<(1) Particle dispersion application process>
In the particle dispersion application step, a particle dispersion obtained by dispersing particles in a low-temperature gelling material is applied to the substrate surface at a temperature at which the particle dispersion becomes a sol state. In FIG. 2, a state in which the operation according to this process is performed is shown in a column “(1) During particle dispersion application process”.

  Here, the “substrate” in the manufacturing method of the present invention is not only a flat plate generally called a substrate, but also a plate in which one or more layers are formed on the substrate surface, or a plate that can be called a substrate. It is a concept including a state in which a single flat plate is formed by simply forming one or more layers. In other words, the “substrate” in the production method of the present invention refers to an object having a target surface on which a particle dispersion layer and a coating layer are to be formed by the production method of the present invention.

  The details of the low temperature gelling material (first material) are as already described in the section of [Laminate]. The particle dispersion is obtained by dispersing particles to be dispersed in a low-temperature gelling material, and when the substance that becomes the particle does not have a desired particle size, the substance that becomes the particle is known by emulsification. By emulsifying in a low-temperature gelling material by a technique, on the other hand, if the substance to be particles has already become the desired particle size, simply mixing them with a known mixer or manual stirring Can be prepared.

At this time, the mixing ratio of the particles and the low-temperature gelling material includes the diameter of the particles, the particles arranged in a single layer state or a multilayer state, or the target thickness of the particle dispersion layer to be formed, the laminate It is desirable to adjust appropriately according to the use etc.
As shown in FIG. 2, in this step, after the particle dispersion is brought to a temperature at which it is in a soft sol state (strictly, the low-temperature gelling material is in a sol state and particles are dispersed therein). Then, it is applied to the substrate surface to be applied.

  The method for applying the particle dispersion onto the substrate surface is not particularly limited, and is a known apparatus that can apply a desired wet thickness such as an applicator, edge coater, screen coater, roll coater, curtain coater, die coater, slide coater. It is preferable to carry out using. It is necessary to heat the particle dispersion to a temperature higher than the temperature at which it sollates to obtain a fluid sol state. For example, when gelatin is used as the low-temperature gelling material, the particle dispersion temperature is set to 30 to 70 ° C. It is preferable to do.

  When the light modulation layer and the protective layer in the light modulation element of the present invention are formed by the production method of the present invention, the display layer coating liquid for forming the light modulation layer (liquid crystal layer) in the step is dispersed in the particles. Used as a liquid and applied to the substrate surface. The display layer coating liquid is obtained by dispersing particles of a light modulating substance or a microencapsulated light modulating substance in a low-temperature gelling material.

The light modulating material may be any material that can change the reflection / transmission / absorption state of incident light, such as various liquid crystal materials, electrophoretic materials, photochromic materials, electrochromic materials, thermal chromic materials, field deposition materials, twists. A ball, an electronic powder fluid, or the like is used, and a cholesteric liquid crystal is particularly preferable. When liquid crystal is used, the “light modulating substance” is dispersed in the liquid crystal drop state and the “microencapsulated light modulating substance” is dispersed in the liquid crystal microcapsule in the display layer coating liquid.
Hereinafter, a method for preparing a coating liquid for a display layer when cholesteric liquid crystal is used as a light modulation substance will be described.

(Preparation of liquid crystal drop emulsion)
The liquid crystal drop emulsion is prepared by emulsifying and dispersing a dispersed phase composed of at least a cholesteric liquid crystal into a continuous phase that is incompatible with the dispersed phase, for example, an aqueous phase. The liquid constituting the continuous phase may be a solvent or a part thereof in the display layer coating liquid (particle dispersion as referred to in the production method of the present invention).

  As a means for emulsification, after mixing the dispersed phase and the continuous phase, a method of dispersing the dispersed phase as fine droplets by mechanical shearing force such as a homogenizer, or passing the dispersed phase through the porous film in the continuous phase A film emulsification method for extruding and dispersing as fine droplets can be employed. In particular, the latter film emulsification method is preferable because the dispersion of the particle diameter of the emulsified droplets is reduced and a liquid crystal drop having a uniform particle diameter can be formed. A small amount of a surfactant or protective colloid for stabilizing the emulsification may be mixed in the continuous phase during emulsification.

(Preparation of liquid crystal microcapsule slurry)
When preparing a liquid crystal microcapsule in which a cholesteric liquid crystal is encapsulated in a polymer shell, a known microencapsulation method such as a phase separation method, an interfacial polymerization method, or an in situ polymerization method can be used. Specifically, a liquid crystal drop prepared as described above is dispersed in a solution containing a polymer shell material, and a polymer shell material phase-separated by coacervation is aggregated around the liquid crystal drop to form a shell. A low molecular weight material in a liquid crystal drop and in a solution, and a shell is formed by polymerization at the interface between the two liquids, or a low molecular weight material and a catalyst in either the liquid crystal drop or the solution. And a method of polymerizing a low molecular weight material by heating to form a shell can be used.

  As the polymer shell, a material that does not dissolve in the encapsulated liquid crystal material is used. For example, gelatin, cellulose derivative, gelatin-gum arabic, gelatin-gellan gum, gelatin-peptone, gelatin-carboxymethylcellulose, polystyrene, polyamide, nylon, polyester, Examples include polyphenyl ester, polyurethane, polyurea, melamine formalin resin, phenol formalin resin, urea formalin resin, acrylic resin, and methacrylic resin.

(concentrated)
The liquid crystal drop emulsion or the liquid crystal microcapsule slurry prepared as described above has a low nonvolatile content concentration, and is concentrated when it cannot be adjusted to the nonvolatile content concentration required for the display layer coating solution at the time of coating. Specific methods of concentration include, for example, a method of removing a continuous phase separated by precipitation or sedimentation by standing or centrifugation using a specific gravity difference between a liquid crystal drop or liquid crystal microcapsule and a continuous phase, The method of filtering with a filter is mentioned.

(Preparation of coating solution for display layer)
A low-temperature gelling material such as gelatin is added to the liquid crystal drop emulsion or liquid crystal microcapsule slurry prepared as described above and concentrated as necessary to prepare a display layer coating solution.

  In order to apply a liquid crystal drop or liquid crystal microcapsule densely on a single layer on a substrate, the content of each component in the liquid crystal drop emulsion or liquid crystal microcapsule slurry is measured using a density meter or hydrometer, It is preferable to adjust the mixing ratio of the non-volatile component of the low-temperature gelling material such as gelatin of the coating liquid for the display layer, the solvent, and the liquid crystal drop or liquid crystal microcapsule.

The ratio (volume ratio) of the nonvolatile component volume to the volume of the coating liquid for the display layer is Sr, the ratio (volume ratio) of the liquid crystal drop or liquid crystal microcapsule to the nonvolatile component volume is Lr, and the average particle size of the liquid crystal drop or liquid crystal microcapsule When the diameter (μm) is D _L and the wet coating thickness (μm) on the substrate is t _W , the ratio A _L of the coating area of the liquid crystal drop or the liquid crystal microcapsule to the coating area is
A _L = (3/2) · (t _W · Sr · Lr / D _L ) (1)
It becomes. And A _L is
0.8 <A _L <1.0 (2)
It is preferable to prepare the coating liquid for the coating display layer so as to be in the range.

The ratio (volume ratio) Sr of the non-volatile component volume to the volume of the display layer coating liquid means that Sr = Y / X when the non-volatile component remaining when the solvent is evaporated from the display layer coating liquid Xml is Yml. In addition, when the non-volatile component Yml includes a Zml liquid crystal drop or a liquid crystal microcapsule, Lr = Z / Y is meant.
In order to prevent breakage due to pressure or the like, the ratio (volume ratio) Lr of the volume of the liquid crystal drop or the liquid crystal microcapsule to the volume of the non-volatile component is preferably 0.9 or less.

  Based on the calculated mixing ratio, the display layer coating liquid is prepared by adjusting the mixing amount of the non-volatile component of the low-temperature gelling material such as gelatin and the solvent with respect to the liquid crystal drop emulsion or the liquid crystal microcapsule slurry. Here, a small amount of a known property modifier such as a thickener, a wettability improving agent, an antifoaming agent, or a drying speed adjusting agent may be added.

  The solvent used for preparing the coating liquid for the display layer dissolves a low-temperature gelling material such as gelatin, and in the case of a liquid crystal drop, a solvent that does not dissolve liquid crystal is used. When using a liquid crystal microcapsule, at least the microcapsule is used. Those that do not dissolve the polymer shell are used. Specific examples of the solvent that can be suitably used include water, a mixture of water and alcohols such as methanol, ethanol, and glycol.

<(2) Cooling process>
In the cooling step, (1) the particle dispersion applied in the particle dispersion application step is cooled to a temperature at which it becomes a gel state. In FIG. 2, the state after the end of the operation in this step is shown in the column “(2) After the end of the cooling step”.

As shown in FIG. 2, in this step, the particle dispersion applied to the substrate surface is in a hard gel state (strictly, the low-temperature gelling material in which particles are dispersed is in a gel state). Cool down to the temperature.
As a specific cooling method, if the gelation temperature (the maximum temperature that maintains the gel state) is equal to or higher than the environmental temperature, it can be simply left to cool down to the environmental temperature. It may be positively cooled by a cooling device such as a plate.

<(3) Coating layer application process>
(Including cooling process)
In the case of including a cooling step, in the coating layer coating step, the coating layer coating solution made of a high-temperature gelling material is converted into a gel state in the cooling step at a temperature at which the coating solution is in a sol state and the particle dispersion is in a gel state. Apply onto the resulting particle dispersion. In FIG. 2, the state in which the operation according to this process is performed is shown in the column “(3) During coating layer application process”.
The details of the high-temperature gelling material (second material) are as already described in the section of [Laminate]. The coating layer coating solution is used with the high-temperature gelling material as it is, but if necessary, known property modifiers such as thickeners, wettability improvers, antifoaming agents, and drying rate modifiers. May be added in a trace amount.

  As a method of applying the coating layer coating liquid on the particle dispersion liquid in the gel state on the substrate surface, the same coating method as exemplified in <(1) Particle dispersion liquid coating process> can be applied as it is. It is necessary to make the sol state with fluidity by lowering the temperature below the minimum temperature at which the coating layer coating solution is gelled. Depending on the material, for example, when a cellulose derivative is used as the high temperature gelling material Is preferably set to a coating layer coating solution temperature of 20 to 40 ° C.

  In this step, the temperature variation within the range in which the sol-gel state of the particle dispersion liquid and coating layer coating liquid is maintained is allowed while maintaining the cooled state in the (2) cooling step. ), A coating layer coating solution is applied. As shown in FIG. 2, in this step, the particle dispersion already applied to the substrate surface is gelled and hardened, and a sol-like soft coating layer coating solution is laminated thereon. The

  In this step, by performing the operation at a low temperature, the already applied particle dispersion liquid is hard in a three-dimensionally cross-linked gel form, and the laminated coating layer coating liquid is in a sol form and has coating suitability. The point is the point. That is, there is a concern that the particle dispersion may flow due to the shear force generated by applying the coating layer coating liquid at this stage and the film thickness becomes non-uniform, or a part of the particle dispersion flows into the coating layer coating liquid side. Alternatively, the concern that the coating layer coating solution flows into the particle dispersion and the two layers are mixed is eliminated.

(When the cooling process is not included)
(2) Cooling step (3) Coating layer coating step Satisfying the above temperature relationship is effective in selecting a high temperature gelling material or a combination of low temperature gelling materials and in a wide range of manufacturing conditions. It is.

  However, if the high temperature gelling material is in the gel state and the low temperature gelling material is in the sol state during the temperature raising step and can proceed to the drying step while maintaining the laminated state, the cooling step is not necessarily required. For example, even if the high-temperature gelling material and the low-temperature gelling material are both in a sol state at the time of lamination, they do not have high compatibility or (4) advance to the temperature raising step before mixing proceeds. Thus, the coating can be laminated in a state in which the coating layer coating solution is gelled and the particle dispersion is solated.

<(4) Temperature raising step>
In the temperature raising step, (1) the particle dispersion coating step to (3) the two solutions (hereinafter sometimes collectively referred to as “coating layer”) coated on the substrate surface in the coating layer coating step. The temperature is raised to a temperature at which the coating layer coating solution is in a gel state and the particle dispersion is changed to a sol state. In FIG. 2, the state after the end of the operation in this step is shown in the column “(4) After the end of the temperature raising step”.

  As shown in FIG. 2, in this step, the particle dispersion applied to the substrate surface is in a soft sol state (strictly, the low-temperature gelling material in which particles are dispersed is in a sol state). Then, the temperature is raised to a temperature at which the coating layer coating solution laminated thereon becomes a gel state.

In this step, the point is that the lower layer particle dispersion of the coating layer is soft in a sol form and the upper coating layer coating liquid is in a gel form and hard. That is, the hard and soft states (sol-gel state) of the upper and lower layers are reversed before and after the temperature rise.
In this step, as a heating device for heating (heating), a convection electric heat device such as an oven or a hot air blow; a conductive heat transfer device such as a hot plate or a heating drum; a radiant heat transfer device such as an infrared heater; be able to.

<(5) Dry curing process>
In the drying and curing step, (4) the temperature raised in the temperature raising step is maintained, and the two liquids that have been applied are dried and cured. As for the temperature maintenance at this time, temperature fluctuation within a range where the coating layer coating solution is in a gel state and the particle dispersion is in a sol state is allowed.

  As the drying and curing temperature, it is necessary to heat each coating layer to a temperature equal to or higher than the freezing point. For example, when gelatin is used as the low-temperature gelling material and cellulose derivative is used as the high-temperature gelling material, The coating layer temperature is preferably 70 ° C. This is of course the same for (4) the temperature raised in the temperature raising step.

  (4) As explained in the temperature raising step, the upper coating layer coating solution in the coating layer is a hard gel that is three-dimensionally cross-linked, so that a part of the particle dispersion is present on the coating layer coating solution side. The concern of flowing in or the concern of the coating layer coating solution flowing into the particle dispersion side and mixing of both layers is eliminated. In addition, since the lower layer particle dispersion is dried and cured in a sol-like soft state, as the solvent volatilizes, the uniformly dispersed particle dispersion gradually changes the position of each other and the surface is naturally uniform. It will change.

  At this time, as described above, the action based on the colloidal solution presumed that the mechanism in which the contained particles are pushed in is working, but the coating layer coating in the form of a gel as the upper layer of the particle dispersion The liquid film is in a covered state, and it is assumed that the film promotes the action of pushing in the particles in the particle dispersion at the time of drying and curing, and the surface is changed to a uniform state with no unevenness due to the particles. In particular, when soft spherical particles are dispersed, the particles can be deformed into a polygonal column shape. Further, by adjusting the mixing ratio of the particles in the particle dispersion as appropriate, it is possible to arrange them in a single layer and in a dense state.

In FIG. 2, the state after the end of the operation in this step is shown in the column “(5) After the drying and curing step (finished)”.
As shown in FIG. 2, after the completion of this step, both the particle dispersion liquid and the coating layer coating liquid are dried to become a solid, thereby forming a particle dispersion layer and a coating layer, respectively, thereby completing the laminate. The obtained laminate has a uniform surface with no irregularities due to the particles (in the example of FIG. 2, the particles are arranged in a single layer and in a dense state).

  As described above in detail with reference to FIG. 2, the manufacturing method of the present invention is described in detail step by step, and according to the manufacturing method of the present invention, particles ranging from (3) coating layer coating step to (5) drying and curing step. Either of the two liquids is in a gel state after the dispersion liquid and the coating layer coating liquid are applied and dried and cured.

  FIG. 3 is a graph showing a change in state of the low temperature gelling material and the high temperature gelling material used in the production method of the present invention with respect to temperature. The graph plots temperature on the horizontal axis and viscosity on the vertical axis for low-temperature gelling materials and high-temperature gelling materials that exhibit ideal temperature-viscosity characteristics. There is no problem even if the material does not have disordered ideal characteristics. As a whole, there is no problem as long as the low-temperature gelling material shows a graph shape that goes down to the left and the high-temperature gelling material shows a graph that goes up to the right.

  As shown in the graph of FIG. 3, first, the operation of the particle dispersion application process is performed at a temperature at which the low temperature gelling material is in a sol state, until the temperature at which the low temperature gelling material is in a gel state ( 2) Cooled in the cooling step and kept at that temperature (that is, at a temperature at which the high temperature gelling material becomes a sol state) (3) The operation of the coating layer application step is performed, and the low temperature gelling material and high temperature gelation The flow of the production method of the present invention is that the temperature of the sol-gel state of the conductive material is reversed (4) the temperature is raised in the temperature raising step, the temperature is maintained, and (5) the material is dried and cured in the drying and curing step. .

  In the example shown in the graph of FIG. 3, (4) In the temperature raising process of the temperature raising step, there is a transient temperature region in which neither the low-temperature gelling material nor the high-temperature gelling material becomes a gel state. However, in the temperature range, at least one part has a three-dimensional cross-linking structure that conforms to the gel state, so that problems due to mixing of both are greatly suppressed. In this specification, “according to the gel state” means a transient solution state between the gel state and the sol state. In the example shown in the graph of FIG. It shall refer to the state (viscosity) of the removed part.

Of course, (4) it is desirable that at least one of the low-temperature gelling material and the high-temperature gelling material is in a gel state throughout the temperature raising process of the temperature raising step. It is desirable that the maximum temperature T _{1 at} which the gel state is maintained is a temperature (T ₁ ≧ T ₂ ) equal to or higher than the temperature T _{2 at} which the high-temperature gelling material changes to the gel state.

FIG. 4 is a graph showing the state change of these materials in the combination of the low temperature gelling material and the high temperature gelling material satisfying this condition, similar to FIG. Thus, if the intersection of the graph is in the gel state region, (4) at least one of the low temperature gelling material and the high temperature gelling material is in the gel state throughout the temperature rising process of the temperature rising step. The relationship between T ₁ and T ₂ is more preferably a temperature difference of 5 ° C. or more (T ₁ ≧ T ₂ +5), and more preferably a temperature difference of 10 ° C. or more (T ₁ ≧ T ₂ +10). preferable.

The temperature T _{3 at} which the low-temperature gelling material changes to the sol state is desirably a temperature (T ₃ ≧ T ₄ ) that is equal to or higher than the maximum temperature T _{4 at} which the high-temperature gelling material maintains the sol state. The relationship between T ₃ and T ₄ is more preferably a temperature difference of 5 ° C. or more (T ₃ ≧ T ₄ +5), and more preferably a temperature difference of 10 ° C. or more (T ₃ ≧ T ₄ +10). .

[Light modulation element]
The light modulation element of the present invention is at least between a pair of electrodes,
A light modulating layer in which particles made of a light modulating substance or a microencapsulated light modulating substance are dispersed and arranged in a material that gels at a low temperature, and the material is cured;
A protective layer formed by curing a material that is laminated in contact with the light modulation layer and gelled at a high temperature;
Is sandwiched.

The light modulation element of the present invention is an embodiment of the laminate of the present invention, and the light modulation layer in the light modulation element of the present invention corresponds to the particle dispersion layer in the laminate of the present invention, and the protective layer corresponds to the coating layer, respectively. To do. The particles dispersedly arranged in the light modulation layer are particles made of a light modulation material or a microencapsulated light modulation material.
In the following, the light modulation element of the present invention will be described in detail by giving two embodiments and giving only a supplementary explanation regarding the light modulation layer and the protective layer and clarifying other components.

<First Embodiment>
FIG. 5 is a schematic configuration diagram of the first embodiment which is an exemplary aspect of the light modulation element of the present invention.
The light modulation element of this embodiment is configured to selectively drive a light modulation layer (liquid crystal layer) by selectively applying a drive signal.

  In the present embodiment, the light modulation element 11 is formed by laminating a substrate 13, an electrode 15, a light modulation layer (liquid crystal layer) 18, a protective layer 16, an electrode 17 and a substrate 20 in order from the display surface side. A laminate layer 28 or a colored layer (light-shielding layer) 22 used in the second embodiment to be described later may be provided between the protective layer 16 and the electrode 17.

(substrate)
The substrates 13 and 20 are members for holding the functional layers on the inner surface and maintaining the structure of the light modulation element 11. The substrates 13 and 20 are sheet-like objects having strength that can withstand external forces, and preferably have flexibility. Specific examples of the material include inorganic sheets (for example, glass / silicon), polymer films (for example, polyethylene terephthalate, polysulfone, polyethersulfone, polycarbonate, and polyethylene naphthalate). Note that at least the substrate 13 on the display surface side has a function of transmitting display light. A known functional film such as an antifouling film, an anti-abrasion film, a light reflection preventing film, or a gas barrier film may be formed on the outer surface.

(electrode)
The electrodes 15 and 17 are members for applying the drive voltage applied from the voltage application unit 21 to each functional layer in the light modulation element 11. Specifically, metal (for example, gold, silver, copper, iron, aluminum), metal oxide (for example, indium oxide, tin oxide, indium tin oxide (ITO)), carbon, and a composite in which these are dispersed in a polymer And conductive thin films formed of conductive organic polymers (for example, polythiophene-based or polyaniline-based). A known functional film such as an adhesion improving film, an antireflection film, or a gas barrier film may be formed on the surface.

(Light modulation layer)
In the present invention, the light modulation layer (liquid crystal layer) includes a light modulation material such as cholesteric liquid crystal, and has a function of modulating the reflection / transmission state of incident light by an electric field, and the selected state can be maintained in an electric field. belongs to. The light modulation layer preferably has a structure that is not deformed by an external force such as bending or pressure.

In the cholesteric liquid crystal 12, liquid crystal molecules are twisted and aligned in a spiral shape, and interference light reflects specific light depending on the helical pitch among light incident from the direction of the helical axis. The orientation is changed by the electric field, and the reflection state can be changed.
Specific liquid crystals that can be used as the cholesteric liquid crystal 12 include steroidal cholesterol derivatives, nematic liquid crystals, and smectic liquid crystals (for example, Schiff base, azo, azoxy, benzoate, biphenyl, terphenyl, and cyclohexyl). Carboxylic acid ester, phenylcyclohexane, biphenylcyclohexane, pyrimidine, dioxane, cyclohexylcyclohexane ester, cyclohexylethane, cyclohexane, tolan, alkenyl, stilbene, condensed polycyclic), or a mixture thereof In addition, there may be mentioned those added with a chiral agent (for example, steroidal cholesterol derivatives, Schiff bases, azos, esters, biphenyls).

  The helical pitch of the cholesteric liquid crystal is adjusted by the chemical structure of the liquid crystal molecules and the amount of chiral agent added to the nematic liquid crystal. For example, when the display color is blue, green, or red, the center wavelength of selective reflection is in the range of 400 nm to 500 nm, 500 nm to 600 nm, or 600 nm to 700 nm, respectively. Further, in order to compensate for the temperature dependence of the helical pitch of the cholesteric liquid crystal, a known method of adding a plurality of chiral agents having different twist directions or opposite temperature dependence may be used.

  The light modulation layer may be formed into a PDCLC (Polymer Dispersed Liquid Crystal Crystal) structure (including microencapsulated one) in which cholesteric liquid crystal is dispersed in a droplet shape in a polymer skeleton. This is preferable in that a self-holding liquid crystal composite that does not deform with respect to the external force can be obtained.

The PDCLC structure is formed by the production method of the present invention by applying a known method of dispersing cholesteric liquid crystal in a polymer matrix. Specifically, the cholesteric liquid crystal is extruded through a porous film in a water layer and dispersed as fine droplets, and then mixed with a low-temperature gelling material such as gelatin, and the resulting coating solution is produced according to the present invention. Apply and dry by the method.
The polymer matrix 14 is formed by curing a low temperature gelling material. The details of the low-temperature gelling material and its curing are as described above.

(Protective layer)
The protective layer 16 is originally a layer provided to protect the light modulation layer 18 so that the light modulation layer 18 is not exposed to the outside when the light modulation element 11 is manufactured. It corresponds to the coating layer referred to in the laminate of the invention and the method for producing the same, and exhibits various functions as the coating layer.
The protective layer 16 is a layer formed by curing a high temperature gelling material. Details of the high temperature gelling material and its curing are as described above.

(Contact terminal)
The contact terminal 19 is a member that contacts the voltage application unit 21 and the light modulation element 11 (electrodes 15 and 17) and conducts both of them. The contact terminal 19 has high conductivity, and the electrodes 15 and 17 and the voltage application unit. Those having a small contact resistance with 21 are selected. It is preferable that the display medium 11 and the voltage application unit 21 have a structure that can be separated from either or both of the electrodes 15 and 17 and the voltage application unit 21 so that the display medium 11 and the voltage application unit 21 can be separated.

  As the contact terminal 19, metal (for example, gold, silver, copper, iron, aluminum), carbon, a composite in which these are dispersed in a polymer, metal oxide (for example, indium oxide, tin oxide, indium tin oxide (ITO) )), Carbon, composites in which these are dispersed in a polymer, terminals made of a conductive organic polymer (for example, polythiophene-based or polyaniline-based), and a clip / connector shape that sandwiches an electrode. .

(Write image)
In order to write an image in the light modulation element 11 of the present embodiment, a voltage appropriately controlled from the voltage application unit 21 by a control circuit (not shown) based on image information from the outside is applied between the electrodes 15 and 17. At this time, the voltage is controlled and applied in an image-like manner for each planar part as viewed from the display surface of the light modulation element 11. By applying this controlled voltage, an image is written in the light modulation element 11.
The applied voltage is controlled in an image-like manner for each planar portion, a voltage exceeding the phase change threshold of the cholesteric liquid crystal 12 and a voltage not exceeding the threshold. The type of phase change can be freely selected according to the purpose.

<Second Embodiment>
FIG. 6 is a schematic configuration diagram of a second embodiment which is another exemplary aspect of the light modulation element of the present invention. The light modulation element of the present embodiment is a display element that can form a monochromatic image by imagewise exposure while applying a voltage. The light modulation element of this embodiment is similar to that of the first embodiment, but is different in that an optical address type liquid crystal device having a configuration including a photoconductive layer is used.
In the following description, the difference from the first embodiment mainly in the configuration, operation, effect, and the like will be described, and members having the same functions as those in the first embodiment are denoted by the same reference numerals in the drawings. Therefore, the description thereof will be omitted as appropriate.

The light modulation element of this embodiment has a configuration capable of performing an optical address operation by irradiating address light and applying a bias signal.
In the present embodiment, the light modulation element 31 includes, in order from the display surface side, the substrate 13, the electrode 15, the light modulation layer 18, the protective layer 16, the laminate layer 28, the colored layer (light-shielding layer) 22, the OPC layer (photoconductive layer). ) 30, the electrode 17 and the substrate 20 are laminated. That is, the laminate layer 28, the colored layer 22, and the OPC layer 30 are interposed between the protective layer 16 and the electrode 17 of the light modulation element 11 in the first embodiment. Only these layers characteristic of this embodiment will be described in detail below.

(OPC layer)
The OPC layer (photoconductive layer) 30 is a layer having an internal photoelectric effect and a characteristic that impedance characteristics change according to the irradiation intensity of address light. An alternating current (AC) operation is possible, and it is preferable that the driving is symmetrical with respect to the address light. In the present embodiment, as the OPC layer 30, a three-layer structure in which an upper charge generation layer (upper CGL) 23, a charge transport layer 24, and a lower charge generation layer (lower CGL) 25 are stacked in order from the upper layer in FIG. Formed.

  The charge generation layers 23 and 25 are layers having a function of generating address carriers by absorbing address light. The charge generation layer 23 mainly uses the amount of light carriers flowing from the display surface side electrode 15 to the writing surface side electrode 17, and the charge generation layer 25 moves from the writing surface side electrode 17 to the display surface side electrode 15. The amount of light carriers flowing through each has an influence. The charge generation layers 23 and 25 are preferably those that absorb address light to generate excitons and can be efficiently separated into free carriers inside the CGL or at the CGL / CTL interface.

  The charge generation layers 23 and 25 are charge generation materials (for example, metal or metal-free phthalocyanine, squalium compound, azurenium compound, perylene pigment, indigo pigment, azo pigment such as bis and tris, quinacridone pigment, pyrrolopyrrole dye, polycyclic quinone pigment, A dry method of directly forming a film of a condensed ring aromatic pigment such as dibromoanthanthrone, a cyanine dye, a xanthene pigment, a charge transfer complex such as polyvinylcarbazole and nitrofluorene, or a symbiotic complex composed of a pyrylium salt dye and a polycarbonate resin) The charge generating material may be a polymer binder (eg, polyvinyl butyral resin, polyarylate resin, polyester resin, phenol resin, vinyl carbazole resin, vinyl formal resin, partially modified vinyl acetal resin, carbonate resin, Resin), vinyl chloride resin, styrene resin, vinyl acetate resin, vinyl acetate resin, silicone resin, etc.) and dispersion or dissolution in an appropriate solvent to prepare a coating solution, which is applied and dried to form a film. It can be formed by a method or the like.

The charge transport layer 24 is a layer having a function of drifting in the direction of the electric field applied by the bias signal when the photocarriers generated in the charge generation layers 23 and 25 are injected.
The charge transport layer 24 efficiently injects free carriers from the charge generation layers 23 and 25 (it is preferable that the ionization potential is close to the charge generation layers 23 and 25), and the injected free carriers hop as fast as possible. Those that move are preferred. In order to increase the dark impedance, it is preferable that the dark current due to the heat carrier is low.

  The charge transport layer 24 is composed of a low-molecular hole transport material (for example, trinitrofluorene compound, polyvinylcarbazole compound, oxadiazole compound, hydrazone compound such as benzylamino hydrazone or quinoline hydrazone, stilbene compound, Triphenylamine compounds, triphenylmethane compounds, benzidine compounds), or low molecular electron transport materials (for example, quinone compounds, tetracyanoquinodimethane compounds, furfreon compounds, xanthone compounds, benzophenone compounds) , Dispersed or dissolved in an appropriate solvent together with a polymer binder (for example, polycarbonate resin, polyarylate resin, polyester resin, polyimide resin, polyamide resin, polystyrene resin, silicon-containing crosslinked resin, etc.) Alternatively the hole transporting material and electron transport material were prepared are dispersed or dissolved in a suitable solvent polymerized material may be formed by which was coated and dried.

(Colored layer)
The colored layer (light-shielding layer) 22 optically separates address light and incident light during writing to prevent malfunction due to mutual interference, and optically separates display light from external light incident from the non-display surface side of the display medium during display. However, this layer is provided for the purpose of preventing the deterioration of image quality, and is not an essential component in the present invention. However, in order to improve the performance of the light modulation element 31, it is a layer desired to be provided. For that purpose, the colored layer 22 is required to have a function of absorbing at least light in the absorption wavelength region of the charge generation layer and light in the reflection wavelength region of the light modulation layer.

  Specifically, the colored layer 22 is an inorganic pigment (for example, cadmium-based, chromium-based, cobalt-based, manganese-based, or carbon-based), or an organic dye or organic pigment (azo-based, anthraquinone-based, indigo-based, or triphenylmethane-based). Nitro, phthalocyanine, perylene, pyrrolopyrrole, quinacridone, polycyclic quinone, squalium, azurenium, cyanine, pyrylium, anthrone) on the side of the charge generation layer 23 of the OPC layer 30 The coating method is prepared by directly applying to a dry method or by dispersing or dissolving these in a suitable solvent together with a polymer binder (for example, polyvinyl alcohol resin, polyacrylic resin, etc.), and applying and drying the solution. The film can be formed by a wet coating method for forming a film.

(Laminate layer)
The laminate layer 28 is a layer provided for the purpose of absorbing unevenness and bonding when the functional layers formed on the inner surfaces of the upper and lower substrates 13 and 20 are bonded, and is an essential component in the present invention. Absent. The laminate layer 28 is made of thermoplastic, thermosetting, or a mixed organic material thereof, and the protective layer 16 on the surface of the light modulation layer 18 and the colored layer 22 are adhered and adhered to each other by heat or pressure. A material that can be used is selected. In addition, it is necessary to have transparency to at least incident light.
Suitable materials for the laminate layer 28 include adhesive / adhesive polymer materials (for example, polyethylene, polypropylene, polyurethane, epoxy, acrylic, rubber, silicone).

(Write image)
In order to write an image to the light modulation element 31 of the present embodiment, a voltage appropriately controlled from the voltage application unit 21 by a control circuit (not shown) based on image information from the outside is applied between the electrodes 15 and 17. Then, the light irradiation unit 26 irradiates the address light imagewise. At this time, the address light is irradiated in an image-like manner for each planar part as viewed from the writing surface of the light modulation element 31 and simultaneously by scanning each surface or by scanning. An image is written in the light modulation element 31 by the irradiation of the image-like address light.

  The applied voltage is controlled to a level that does not exceed the phase change threshold value of the cholesteric liquid crystal 12 in the portion that is not irradiated with the address light, and that only the portion that is irradiated with the address light exceeds the threshold value of the phase change. The The type of phase change can be freely selected according to the purpose.

<Third Embodiment>
The third embodiment has the same layer configuration as that of the light modulation element shown in the first embodiment, but the display layer before reaching the temperature raising step remains in a sol state before being cooled and gelled, It is different in that the coating layer is applied at a high speed and the process proceeds to the temperature raising step (the configuration is the same as that of the first embodiment, so the drawing is omitted. For the operation, see FIG. 2).

A low temperature gelling material (first material) constituting the display layer (particle dispersion layer) and a coating solution (particle dispersion liquid) in a transient state or sol state heated to a temperature above the maximum gelation temperature T ₁ containing particles. ) With a slide coater ((1) particle dispersion coating step), and subsequently a coating solution (coating layer coating) containing a high-temperature gelling material constituting the protective layer (coating layer) and having a minimum gelation temperature T ₂ or less. (Liquid) is applied ((3) coating layer application step).

At this time, the coating layer constituting the display layer (particle dispersion layer) is in a transitional state or a sol state, but the coating layer coating solution is left in the sol state without cooling the display layer (particle dispersion layer). Even if coating is repeated, mixing at the interface can be made difficult to occur by adjusting the temperature of the coating solution. That is, when multilayer coating is performed with a slide coater, the particle dispersion is set to a temperature at which the sol state is obtained (for example, 60 ° C.), and the coating layer coating solution is applied to the sol state at a lower temperature (for example, room temperature). If it does so, in the interface which both contact | connected, heat exchange will generate | occur | produce between both and it will go to thermal equilibrium (for example, about 40 degreeC). Therefore, the particle dispersion liquid changes from 60 ° C. to 40 ° C. and the coating layer coating liquid changes from room temperature to 40 ° C., and the mixing hardly occurs at the interface. .
About this laminated body, a single layer dense film | membrane can be manufactured by performing a temperature rising process and a drying hardening process like 1st Embodiment.

  Although the light modulation element of the present invention has been described in detail with reference to preferred embodiments, the present invention is not limited to the above embodiments. For example, in the above-described embodiments, the light modulation element for forming a monochromatic image having only one light modulation layer has been described as an example. However, a plurality of light modulation layers and other layers may be provided as necessary. A light modulation element capable of forming a color image may be used, and at this time, a light modulation element capable of forming a full color image may be formed by laminating a light modulation layer capable of displaying at least three primary colors of blue, green, and red.

In any case, the present invention can be applied as long as it is a light modulation element composed of a laminated body in which a light modulation layer and a protective layer are laminated next to each other. At this time, only one pair of the configurations of the light modulation layer and the protective layer defined in the present invention may be included, or two or more pairs may be included.
In the light modulation element of the present invention, the protective layer may have other functions.

  In addition, those skilled in the art can appropriately modify the laminate of the present invention, the production method of the present invention, or the light modulation element of the present invention according to conventionally known knowledge. Of course, such modifications are also included in the scope of the present invention as long as the laminate of the present invention, the production method of the present invention, or the structure of the light modulation element of the present invention are provided.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated more concretely, this invention is not limited to a following example.
(Example 1)
<Preparation of coating liquid (particle dispersion) for light modulation layer>
Nematic liquid crystal (trade name: E7, manufactured by Merck & Co., Inc.) 77.5% by mass, chiral agent 1 (trade name: CB15, manufactured by Merck & Co.) 18.8% by mass, chiral agent 2 (trade name: R1011, Merck & Co., Inc.) A cholesteric liquid crystal which selectively reflects green color light was prepared by mixing 3.7% by mass.

Using a membrane emulsification apparatus (trade name: Microkit, manufactured by SPG Techno Co., Ltd.) in which a ceramic porous membrane having an average pore size of 4.2 μm is set, a nitrogen pressure of about 11.8 kPa (0.12 kgf / cm ² ) Then, 2 g of the cholesteric liquid crystal was emulsified in 100 ml of a 0.25 mass% aqueous sodium dodecylbenzenesulfonate solution to obtain an emulsion.

  The obtained emulsion was arbitrarily sampled and photographed with a digital microscope (trade name: VHX-200, manufactured by Keyence Corporation), and about 2500 particles photographed were measured for particle size measurement software (trade name: A Image-kun, Asahi Kasei Engineering). The average particle size of cholesteric liquid crystal drops was 14.9 μm in number average, and the standard deviation of particle size was 1.32 μm, which was close to monodispersion.

  Next, the obtained emulsion was allowed to stand to settle the cholesteric liquid crystal drop, and the supernatant was removed to obtain a concentrated emulsion. It was 0.535 when the volume ratio of the cholesteric liquid crystal drop in a concentrated emulsion was measured using the density meter (brand name: DMA35n, Nihon Shibel Hegner company make).

  The ratio AL of the coating area of the liquid crystal drop to the coating area was set to 0.95, and the wet coating thickness was set to 90 μm. Using the average particle diameter (14.9 μm) of the cholesteric liquid crystal drop and the wet coating thickness (90 μm) on the display substrate, the volume ratio of the cholesteric liquid crystal drop (Sr × Lr) was determined to be 0.10 (10% by volume).

Using this value as a guide, a 7.7% by mass aqueous solution of acidic bone gelatin (jelly strength: 314 g, sol viscosity (60 ° C.): 3.2 mPa · S, manufactured by Nippi Co., Ltd.) per 1 part by mass of this concentrated emulsion. By adding 4 parts by mass, a light modulation layer coating solution having a nonvolatile volume fraction in the light modulation layer coating solution of about 0.15 and a cholesteric liquid crystal volume fraction in the nonvolatile content of about 0.70 was prepared.
The result of having measured the viscosity change with respect to the temperature of the obtained coating liquid for light modulation layers with the vibration type viscometer (brand name: VM-10A-M, CBC Materials company make) is shown in FIG. 7 with a graph. The maximum temperature at which the coating liquid for light modulation layer can maintain a gel state was about 38 ° C.

<Application of light modulation layer coating solution>
125 μm-thick polyethylene with ITO transparent electrode (surface resistance 300Ω / □) formed on one side in the sol state after heating the coating liquid for light modulation layer to 50 ° C. Applicator with micrometer (trade name: K) with a gap adjusted so that the wet film thickness after application is 90 μm on the surface of the ITO transparent electrode side of a terephthalate (PET) substrate (trade name: High Beam, manufactured by Toray Industries, Inc.) It was applied with a paint applicator (manufactured by Matsuo Sangyo Co., Ltd.) (see (1) during the particle dispersion application step in FIG. 2).
Next, the coated substrate was cooled to 25 ° C. to gelatinize the gelatin contained in the light modulation layer coating solution (see (2) after completion of the cooling step in FIG. 2).

<Preparation of protective layer coating solution (coating layer coating solution)>
As a protective layer coating solution, a 12% by weight aqueous solution of methylcellulose (trade name: SM4, manufactured by Shin-Etsu Chemical Co., Ltd.) to which 0.1% by weight of a surfactant (trade name: Dynol 604, manufactured by Nissin Chemical Industry Co., Ltd.) is added. Was prepared.
The result of having measured the viscosity change with respect to the temperature of the obtained coating liquid for protective layers with the vibration viscometer (brand name: VM-10A-M, CBC Materials company make) is shown in FIG. 7 with a graph. The temperature at which the protective layer coating solution changed to a gel state was about 33 ° C.

<Application of protective layer coating solution>
The gap was adjusted so that the wet film thickness after coating was 20 μm on the light modulation layer coating liquid already gelled at 25 ° C. in which methylcellulose contained in the protective layer coating liquid was in a sol state. The protective layer coating solution was applied with an applicator with a micrometer (trade name: K paint applicator, manufactured by Matsuo Sangyo Co., Ltd.) (see (3) Coating layer application step in FIG. 2).

<Drying and curing of coating layer (light modulation layer and protective layer)>
The substrate after applying the light modulation layer coating solution and the protective layer coating solution was placed on a hot plate at 55 ° C. and held for 10 minutes. From the results of the viscosity measurement shown in the graph of FIG. 7, the gelatin of the light modulation layer coating liquid changes from the gel state to the sol state and the methyl cellulose of the protective layer coating liquid changes from the sol state to the gel state at the initial stage of drying. (Refer to (4) after the temperature raising step in FIG. 2).

FIGS. 8A to 8D show the results of photographing the behavior of the coating liquid for light modulation layer in the drying and curing process with a digital microscope (trade name: VHX-200, manufactured by Keyence Corporation). In FIG. 8, time elapses in the order of (A) to (D).
In the light modulation layer coating solution, as drying progressed, the cholesteric liquid crystal drop gradually changed to a single layer state while gradually changing the positional relationship between each other (FIGS. 8A to 8C). reference). When the solvent further evaporates and the coating film is completely dried, as shown in FIG. 8 (D), a light modulation layer in which cholesteric liquid crystal drops transformed into a polyhedron are densely arranged in a single layer, and a protective layer laminated thereon And a laminate A formed on the substrate surface was obtained (see (5) after the drying and curing step (finished) in FIG. 2).

  The thickness of the light modulation layer in the laminate A measured by a laser 3D microscope (trade name: VK-8500, manufactured by Keyence Corporation) is 12.6 μm, and the average particle diameter D (14.9 μm) of the cholesteric liquid crystal drop and the light modulation layer The relationship with the layer thickness t was D = 1.18t. The thickness of the protective layer was 2.2 μm, and the number average particle size of the cholesteric liquid crystal drop in the light modulation layer was about 16.8 μm.

<Cellization>
A 9.0% by weight polyvinyl alcohol aqueous solution in which a carbon black pigment is dispersed at a rate of 23 g / l on the surface of the same ITO substrate as the substrate used in the section <Coating of light modulation layer coating solution> on the ITO transparent electrode side. Was coated by spin coating to a thickness of 1.3 μm to form a light shielding layer.

On the formed light shielding layer, a urethane-based laminating agent (LX719 / KY-90, manufactured by Dainippon Ink & Chemicals, Inc.) is spin-coated to a thickness of 1 μm to form an adhesive layer (laminate layer). A laminate B was obtained.
The produced two laminates A and B were overlapped so that the protective layer and the adhesive layer face each other, and adhered through a laminator at 100 ° C. to obtain the light modulation element of Example 1.

(Example 2)
In Example 1, methylcellulose (trade name: SM15, manufactured by Shin-Etsu Chemical Co., Ltd.) to which 0.1% by mass of a surfactant (trade name: Dynol 604, manufactured by Nissin Chemical Industry Co., Ltd.) was added as a coating solution for the protective layer. A laminate A ′ was obtained in the same manner as in Example 1 except that a 5% by mass aqueous solution was used and the protective layer coating solution was applied so that the wet film thickness after coating was 10 μm. In addition, the multilayer body A ′ was used as a cell in the same manner as in Example 1 to obtain a light modulation element of Example 2.

  The result of having measured the viscosity change with respect to the temperature of the coating liquid for protective layers in Example 2 with the vibration viscometer (brand name: VM-10A-M, CBC Materials company make) is shown in FIG. 7 with a graph. The temperature at which the protective layer coating solution changed to a gel state was about 45 ° C.

  In this example, the temperature at which the protective layer coating solution changes to the gel state is higher than the maximum temperature (about 38 ° C.) at which the light modulation layer coating solution maintains the gel state. However, the maximum temperature (about 39 ° C.) at which the protective layer coating solution can maintain the sol state is lower than the minimum temperature (about 43 ° C.) at which the light modulation layer coating solution changes to the sol state.

  FIG. 9 shows the results of photographing the laminate A ′ with a digital microscope (trade name: VHX-200, manufactured by Keyence Corporation). As can be seen from the photograph in FIG. 9, in this example, although the liquid crystal drop is slightly spherical compared to Example 1, the light modulation layer in which the cholesteric liquid crystal drops are arranged in a single layer densely, A layered product A ′ in which the laminated protective layer was formed on the substrate surface was obtained.

(Comparative Example 1)
In Example 1, polyvinyl alcohol (trade name: Poval PVA210, manufactured by Kuraray Co., Ltd.) to which 0.1% by mass of a surfactant (trade name: Dynol 604, manufactured by Nissin Chemical Industry Co., Ltd.) was added as a coating solution for the protective layer. A laminate B was obtained in the same manner as in Example 1 except that the 7 wt% aqueous solution was applied and the protective layer coating solution was applied so that the wet film thickness after coating was 30 μm. The protective layer coating solution used in Comparative Example 1 did not gel even when the temperature was changed.

FIG. 10 shows the result of photographing the laminate B obtained in the comparative example with a digital microscope (trade name: VHX-200, manufactured by Keyence Corporation). As can be seen from the photograph of FIG. 10, in this comparative example, the liquid crystal drop is somewhat spherical compared to Example 1, and the light modulation layer and the protective layer are partially mixed to protect the cholesteric liquid crystal drop. Leaking over the layer was observed.
Further, using the laminate B, a cell was formed in the same manner as in Example 1 to obtain a light modulation element of Comparative Example 1.

(Measurement of display characteristics)
With respect to the obtained light modulation elements of Example 1 and Comparative Example 1, display characteristics in the planar state and the focal conic state were measured using an integrating sphere type spectrocolorimeter (CM2002 type, manufactured by Minolta). Specifically, the reflectivity in the state (d8 / SCE condition) in which the specularly reflected light was removed under diffuse illumination was determined with the reflectivity of the complete diffuser as 100%. The results are shown in a graph in FIG.

  As shown in FIG. 11, Example 1 has a higher reflectance in the planar selective reflection state than Comparative Example 1, and has a bright display. In Example 1, since the cholesteric liquid crystal drop is a polyhedron, it is presumed that the disorder of the orientation in the drop is small and the reflection efficiency is high.

  On the other hand, in Example 1, the reflectance in the focal conic transmission state is lower than that in Comparative Example 1, and the display is high in contrast with black display. In Example 1, the boundary between the light modulation layer and the protective layer is clear and the structure of the light modulation layer is not broken, but in Comparative Example 1, the boundary between the light modulation layer and the protective layer is unclear, The structure collapses and the cholesteric liquid crystal leaks out onto the protective layer, and the leaked liquid crystal is a display defect between the protective layer and the adhesive layer, resulting in an unnecessary scattering source and focal conic transmission. It is estimated that the condition has deteriorated.

  As described above, the laminate of the present invention and the method for producing the same can be applied to a light modulating element and the production thereof, as well as to a variety of other laminates including a particle dispersion layer and the production thereof. I don't know. Specifically, for example, colored sheets, fluorescent light emitting sheets, silver salt photographic films, optical recording elements, magnetic recording elements, laser elements, artificial opal sheets, interference reflection sheets, antireflection sheets, microlens array sheets, adhesive sheets, catalysts It can be applied to sheets, sensor sheets, conductive sheets, electromagnetic shielding sheets, filtering sheets, suction sheets, and the like.

It is sectional drawing of the laminated body which is an exemplary one aspect | mode of this invention. FIG. 2 is a list schematically showing the appearance (cross section) and the state of each layer in the order of steps of the production process of the laminate according to the laminate production method of the present invention, taking the laminate shown in FIG. 1 as an example. It is a graph which shows the state change with respect to the temperature of the low temperature gelling material which shows an ideal temperature-viscosity characteristic, and high temperature gelling material, and plots temperature on a horizontal axis and a vertical axis | shaft. It is a graph which shows the state change with respect to the temperature of both materials in the combination of the low temperature gelling material suitable for this invention, and a high temperature gelling material, and plots temperature on a horizontal axis and a viscosity on a vertical axis | shaft. It is a schematic block diagram of 1st Embodiment which is an exemplary aspect of the light modulation element of this invention. It is a schematic block diagram of 2nd Embodiment which is another one aspect | mode of the light modulation element of this invention. It is a graph which shows the viscosity characteristic with respect to the temperature of each coating liquid of an Example. In manufacture of the laminated body of Example 1, it is a photograph which shows the result of having image | photographed the behavior of the coating liquid for light modulation layers in a drying hardening process with a digital microscope, time passes in order of (A)-(D), ( D) is a photograph of the finally produced laminate. It is the photograph which image | photographed the laminated body of Example 2 with the digital microscope. It is the photograph which image | photographed the laminated body of the comparative example 1 with the digital microscope. It is a graph which shows the result of having measured the display characteristic in the planar state and the focal conic state of the light modulation element of Example 1 and Comparative Example 1. It is a schematic explanatory view showing the relationship between the molecular orientation and optical characteristics of cholesteric liquid crystal, wherein (A) is in the planar phase, (B) is in the focal conic phase, and (C) is in the homeotropic phase. It is a graph for demonstrating the switching behavior of a cholesteric liquid crystal. It is a schematic diagram which represents typically a mode that image writing is performed with the exposure apparatus with respect to the conventional general light modulation element.

Explanation of symbols

  2: particles, 4: matrix (cured from the first material), 6: coating layer, 8: particle dispersion layer, 10, 20: substrate, 11, 31: light modulation element (laminate), 12: cholesteric Liquid crystal (particles), 13, 20: substrate, 14: polymer matrix (cured from the first material), 15, 17: electrode, 16: protective layer (coating layer), 18: light modulation layer (particle dispersion) Layer), 19: contact terminal, 21: voltage application section, 22: colored layer, 23, 25: charge generation layer, 24: charge transport layer, 26: light irradiation section, 28: laminate layer, 30: OPC layer

Claims (19)

A particle dispersion layer in which particles are dispersed and arranged in a first material that changes from a gel state to a sol state as the temperature rises, and a coating layer that includes a second material that changes from the sol state to a gel state as the temperature rises And the sol-state particle dispersion layer and the gel-state coating layer are laminated in contact with each other. The laminate according to claim 1, wherein the particle dispersion layer in a sol state and the coating layer in a gel state are dried. The maximum temperature T _{1 at} which the first material maintains the gel state in a state including the solvent is equal to or higher than the temperature T _{2 at} which the second material changes to the gel state (T ₁ ≧ T ₂ ). The laminate according to claim 1. The laminate according to claim 1, wherein the particles are dispersed and arranged in a single layer state in the particle dispersion layer. The laminate according to claim 3, wherein the particle diameter D of the particles and the layer thickness t of the particle dispersion layer satisfy the following relational expression (A).
0.5t ≦ D ≦ 2t ... Relational expression (A) A particle dispersion layer including a particle dispersion in which particles are dispersed in a first material that changes from a gel state to a sol state as the temperature rises, and a second material that changes from the sol state to the gel state as the temperature rises A temperature rising step of heating the coating layer containing the coating layer coating liquid, in which the coating layer coating liquid is in a gel state and the particle dispersion is overlaid in a sol state;
The temperature is raised in a temperature raising step, the coating layer coating solution is in a gel state and the temperature at which the particle dispersion becomes a sol state is maintained, and a drying and curing step of drying and curing both the coated liquids;
The manufacturing method of the laminated body characterized by including. Performed prior to the temperature raising step,
A particle dispersion applying step of applying a particle dispersion in which particles are dispersed in the first material to a substrate surface at a temperature at which the particle dispersion becomes a sol;
A cooling step of cooling to a temperature at which the particle dispersion applied in the particle dispersion application step becomes a gel state;
Coating that coats the coating liquid comprising the second material on the particle dispersion that has been in a gel state in the cooling step at a temperature at which the coating liquid is in a sol state and the particle dispersion liquid is in a gel state. A layer coating process;
The manufacturing method of the laminated body of Claim 6 characterized by the above-mentioned. The maximum temperature T _{1 at} which the first material maintains a gel state is a temperature (T ₁ ≧ T ₂ ) equal to or higher than a temperature T _{2 at} which the second material changes to a gel state. The manufacturing method of the laminated body of 6. The method for producing a laminate according to claim 6, wherein the second material is a solution containing cellulose or a derivative thereof and a solvent. The method for producing a laminate according to claim 6, wherein the first material is a solution containing gelatin or a derivative thereof and a solvent. In the particle dispersion application step, the use of a particle dispersion in which the concentration of the particles is adjusted so that the particles are dispersed and arranged in a single layer state in the particle dispersion layer of the laminate after production. The manufacturing method of the laminated body of Claim 7 characterized by the above-mentioned. A light modulation layer in which particles made of a light modulation substance or a microencapsulated light modulation substance are dispersed and disposed between at least a pair of electrodes in a first material that changes from a gel state to a sol state as the temperature rises; A protective layer containing a second material that changes from a sol state to a gel state as the temperature rises, and the light modulation layer in a sol state and the protective layer in a gel state are laminated in contact with each other A characteristic light modulation element. The light modulation element according to claim 12, wherein the light modulation layer in a sol state and the protective layer in a gel state are dried. The light modulation element according to claim 12, wherein the light modulation material is a cholesteric liquid crystal. The light modulation element according to claim 12, wherein the protective layer is made of cellulose or a derivative thereof. The light modulation element according to claim 12, wherein the light modulation layer is formed by dispersing and disposing the particles in gelatin or a derivative thereof. The light modulation element according to claim 10, wherein the particles have a polyhedral shape. The light modulation element according to claim 12, wherein the particles are densely dispersed and arranged in a single layer state in the light modulation layer. The light modulation element according to claim 18, wherein the particle diameter D of the particles and the layer thickness t of the light modulation layer satisfy the following relational expression (A).
0.5t ≦ D ≦ 2t ... Relational expression (A)

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