JP2002156665A - Chemical gel, method for preparing the same, and display method and display device using gel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for preparing chemical gel in a physical gel matrix (a matrix made of a material which can change from a gel state to a sol state), to provide a chemical gel prepared by the above method, and to provide a display method and a display device which use the gel, particularly a display method and a display device in which not digital gradation such as area gradation but analog gradation is made possible. SOLUTION: 1. By the method for preparing chemical gel, a chemical gel in a desired form can be produced in a physical gel matrix 2. By the display method, an image is displayed by using a display device having a light transmitting display side substrate, a counter non-display side substrate, a liquid housed between the substrates, and a gel which expands and contracts (swells and shrinks) according to the external stimulation. The state of the gel in contact with the display substrate or not in contact with the display substrate is produced by the expansion and contraction of the gel so as to control the incident light to display. A gradation display is carried out by controlling the contact area between the gel on each pixel and the display side substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a chemical gel, a method for producing the same, and a display method and a display device using the gel.

[0002]

2. Description of the Related Art It has recently been reported by Tanaka et al. That a chemical gel (polymer gel) undergoes a volume change due to a change in an external environment (solvent, temperature, pH, electric field, etc.) [Phys. R
ev. Letts. , 40, 820 (1978): Sc
issue, 218, 467 (1982)]. afterwards,
Since this volume change is reversible, various studies have been made as being applicable to switches, sensors, actuators, display elements, and the like. Such a chemical gel is formed in a form in which a solvent is taken into a three-dimensional network structure of a polymer, but since the network structure is composed of chemical bonds, after gelation, processability is increased. Absent. Therefore, a mold having a desired shape was prepared, and a gelling reaction was carried out in the mold to prepare a chemical gel having a desired shape.
However, in this method, it is difficult to produce a gel having a very small (thin) shape to be used for an actuator or the like, because the gel may be broken due to the mold not being peeled off from the gel well.

[0003] Further, as a prior art in which a chemical gel is applied to a display element, there are, for example, JP-A-61-149926, JP-A-63-13021 and JP-A-9-160081. According to JP-A-63-13021, a monomer solution state before gelation is applied onto a substrate, and the monomers in the solution are photopolymerized through a dot matrix mask to form a dot matrix form. Although a chemical gel is obtained, a dot matrix gel can be obtained by this method, but the liquid remains on the substrate until the light is irradiated, and the liquid surface deforms due to evaporation, handling, and air flow. There is an easy disadvantage.
Further, as the thickness of the liquid increases, it becomes difficult to accurately control the shape of the gel due to disturbance of the monomer in the liquid.

On the other hand, display devices include a self-luminous type such as a CRT, a plasma display, an EL display, and a fluorescent display tube, and a non-luminous type such as a liquid crystal display utilizing reflected light and transmitted light. Each has been put to practical use. However, in recent years, due to the development of information systems, VDT (Visual Data Termi) has been
nal) Work is increasing rapidly, and a non-light-emitting display screen is desirable in view of fatigue. For this reason, recently, the spread of liquid crystal displays has progressed to replace the CRT, but the viewing angle is narrow and the contrast between light and dark is not sufficient. In order to solve such a problem, there has been proposed a display device that uses a gel that swells / shrinks or bends in response to an external stimulus, and that performs display by adjusting incident light by deformation of the gel (described above). However, as shown in FIG. 1, the gel absorbs and swells and discharges the solvent due to external stimuli such as temperature, electric field, light, pH, ion concentration, and solvent composition. Display is performed by adjusting the light incident on each pixel to obtain a contrast by utilizing a contracting phenomenon or a bending phenomenon.
Unlike the liquid crystal display, this method has a wide viewing angle, does not require a deflecting plate and the like, and has a high light use efficiency, so that the screen can be made bright. However, there is a drawback that gradation display is difficult.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a method for producing a chemical gel in a physical gel matrix (a matrix made of a material capable of changing from a gel state to a sol state), and a chemical gel produced by the method. It is another object of the present invention to provide a display method and a display device using a gel, and in particular, a display method and a display device that enable analog gray scale instead of digital gray scale such as area gray scale.

[0006]

Means for Solving the Problems The above problems are as follows:
The invention of 20) (hereinafter referred to as inventions 1 to 20) is solved. 1) A method for producing a chemical gel, which comprises producing a chemical gel of an arbitrary shape in a physical gel matrix (a matrix made of a material capable of changing from a gel state to a sol state). 2) A system capable of producing a physical gel is prepared, and at a temperature equal to or higher than the sol transition temperature of the physical gel, a monomer capable of forming a chemical gel without reacting with the physical gel constituent material is formed into a sol with a solvent. In addition, the system is then cooled to a temperature lower than the sol transition temperature of the physical gel to gel the system, and in this state, energy for polymerization of the monomer is applied only to a desired position to form a shape-controlled chemical gel. A method for producing a chemical gel as described in 1) above, which is characterized by the following. 3) The method for producing a chemical gel according to 1) or 2), wherein the energy for polymerization is caused by light or heat. 4) The method for producing a chemical gel according to any one of 1) to 3), wherein the physical gel is formed into a sol after the chemical gel is generated. 5) The method for producing a chemical gel according to any one of 1) to 4), wherein the chemical gel is generated in a dot matrix on the substrate. 6) A chemical gel produced by the method according to any one of 1) to 5). 7) A display device using the chemical gel according to 6). 8) A display device having a light-transmitting display-side substrate, a non-display-side substrate opposed thereto, a liquid contained between the two substrates, and a gel that expands and contracts (swells and contracts) in response to an external stimulus is used. A display method in which the gel is brought into contact with or not in contact with the display-side substrate surface by the expansion and contraction of the gel, and the display is performed by adjusting the incident light. A display method, wherein gradation display is performed by controlling an area. 9) From a state in which the gel on the pixel does not contact the display-side substrate surface, a part of the gel first comes into contact with the display-side substrate surface due to an external stimulus, and further, the contact area becomes continuous in response to the external stimulus. Or the contact area decreases continuously in response to an external stimulus from a state in which all of the gel on the pixel is in contact with the display-side substrate surface 8).
Display method of description. 10) The display method according to 8) or 9), wherein the external stimulus for expanding and contracting the gel is an electric field. 11) A light-transmitting display-side substrate, a non-display-side substrate opposed thereto, a liquid contained between the two substrates, and a gel that expands and contracts (swells and contracts) in response to an external stimulus. A state in which the gel contacts or does not contact the display-side substrate surface due to expansion and contraction, and a display device in which display is performed by adjusting incident light, wherein the contact area between the gel on each pixel and the display-side substrate surface Characterized in that the display is set to perform gradation display by the control of (1). 12) From a state where the gel on the pixel is not in contact with the display-side substrate surface, first, a part of the gel comes into contact with the display-side substrate surface due to an external stimulus. Or the contact area is set so as to continuously decrease in response to an external stimulus from a state where all of the gel on the pixel is in contact with the display-side substrate surface. The display device according to (1). 13) The display device according to 11) or 12), wherein the external stimulus for expanding and contracting the gel is an electric field. 14) The display device according to any one of 11) to 13), wherein the surface of the gel on the side contacting the display-side substrate is not parallel to the surface of the display-side substrate. 15) The gel surface on the side contacting the display-side substrate and / or the display-side substrate surface is uneven.
13. The display device according to any one of items 13 to 13. 16) The display device according to any one of 11) to 13), wherein the gel on each pixel is at least two or more composite gels having different responsiveness due to an external stimulus. 17) A reflective display device 11)
16. The display device according to any one of claims 16). 18) The display device according to any one of 11) to 17), wherein the display-side substrate surface in contact with the liquid has low wettability with respect to the liquid (the contact angle is a receding contact angle of 50 ° or more). 19) The display method according to any one of 8) to 10), wherein the chemical gel according to 6) is used. 20) The display device according to any one of 11) to 18), wherein the chemical gel according to 6) is used.

Hereinafter, the present invention will be described in detail. First, a chemical gel (polymer gel) and a method for producing the same will be described. The gel referred to in the present invention refers to a state in which a solvent has been incorporated into a three-dimensional network structure. In addition, the physical gel used in the present invention is from a gel state to a solution state (sol state).
The physical gel matrix refers to a matrix made of a material that can be changed to a physical gel constituent material. As long as the material can be changed from the gel state to the sol state, the structure of the crosslinked portion of the three-dimensional network is not particularly limited, but the crosslinked structure is generally based on a secondary bonding force other than a covalent bond. There are many things. Here, the secondary bonding force is based on an intermolecular force bond (hydrogen bond, molecular orientation, helix formation, lamellar formation, or the like) or ionic bond.

[0008] The change of the gel into a solution (sol formation) due to intermolecular force bonding can generally be caused by raising the temperature (sometimes depending on the environment such as pH). The material that can be used is not particularly limited as long as it does not adversely affect the formation of a chemical gel described below. Specifically, natural polymer gels (polysaccharide gels, DNA gels, etc.), low molecular gelling agents (alkyl Gels based on amide compounds and the like can be used. The change of the gel into a solution (sol formation) by ionic bonding can generally be caused by changing the pH or ionic strength. Specifically, a natural polymer gel (eg, a polysaccharide gel containing ionic species) or a synthetic polymer electrolyte gel (eg, a polymer electrolyte containing polyvalent ions, polyion complex, etc.) can be used. Further, even if the cross-linking portion is a covalent bond, for example, in the case of a gel formed by an acetal bond or an ester bond, p
It is possible to bring about a solution state by causing hydrolysis by H change, and such a material can also be used.

[0009] The chemical gel of the present invention is characterized by a disturbance (temperature change, p
Changes in the environment in which the gel is placed, such as changes in H and ionic strength)
In contrast, the crosslinked portion is stable and does not change. Of course, it is only necessary that the system is stable in the used system, and it is not necessary to be stable with respect to all the disturbance elements described above. Preferred is a synthetic polymer gel, which can be produced by any of a method of forming a bond required for a crosslinked structure simultaneously with polymerization and a method of crosslinking a linear polymer later. One method is to polymerize a vinyl monomer in the presence of a divinyl monomer as a crosslinking agent. Heat, light, radiation, etc. are used to initiate the reaction. In the latter method, a reactive species (crosslinking agent: one that can react with a functional group) is added to a polymer solution having a functional group, and heat,
The two react by light or the like to form a three-dimensional structure.

The chemical gel of the present invention must be capable of changing its shape in response to an environmental change (external stimulus) in which the gel is placed. As a gel which is deformed by an external stimulus, a liquid-absorbing polymer which absorbs a liquid, swells, and discharges and contracts, for example, a crosslinkable monomer such as a known acrylic compound, divinylbenzene, N, N'-methylenebisacrylamide, etc. And those made of polyether, polyvinyl alcohol, cellulose, starch, and polyacrylic acid-based materials obtained by graft polymerization of In particular, a main component is an acrylamide derivative, a crosslinkable polymer obtained by polymerizing an ion dissociation monomer and a crosslinkable monomer, a copolymer of methyl methacrylate and acrylic acid,
A gel composed of a polyacrylate or the like is preferably used. Examples of the polymer that forms a gel that bends due to an external stimulus include a polyacrylic acid-polyvinyl alcohol composite. Among them, when applied to a display device described later, a material that responds to an electric field that is an external stimulus is preferable.

The method for producing a chemical gel of the present invention is characterized in that a chemical gel is formed in a physical gel matrix (a matrix composed of a material capable of changing from a gel state to a sol state). As a method, a system capable of producing the above-mentioned physical gel is prepared, and the above-mentioned chemical solution is added to the sol-formed system at a temperature equal to or higher than the sol transition temperature of the physical gel (that is, in a state of fluidity). A gel-forming liquid (usually a mixture of a monofunctional monomer and a polyfunctional monomer) and, if necessary, a reaction initiator (photoinitiator, thermal initiator), a solvent, additives, etc., are added to the liquid before gelation. prepare. At this time, it is preferable that the system is a homogeneous system, that is, a state in which the physical gel material and the chemical gel material are uniformly dissolved in the solvent, and it is necessary that they do not react with each other in the working environment. Solvent is 1
It may be a seed or a mixture of two or more. The amount of the monomer capable of forming a chemical gel is within a range in which the sol can be turned into a physical gel when cooled below the sol transition temperature, and a range in which the monomer can generate a chemical gel by receiving energy such as heat and light. There is no particular limitation so long as it is determined appropriately according to the material to be used so that the change in shape of the chemical gel due to external stimulus is preferable.

When the physical gel in the liquid prepared as described above undergoes a transition by cooling, the system gels and can be treated as an apparent solid. If light is applied in this state (when polymerization is initiated by light), only the location where the light is applied will cause a reaction and a chemical gel will be generated, so it is possible to control the shape of the chemical gel by controlling the position where the light is applied. Become.
Further, by using a light source having a minute spot such as a laser beam as light, fine processing is possible. On the other hand, if the light is condensed using a lens and the temperature is raised locally (in the case where polymerization is initiated by heat), the chemical gel is generated only in the area where the temperature has risen. By doing so, the shape of the chemical gel can be controlled.

Further, if the method of the present invention is used, since the chemical gel is basically in a solid state (gel state) before the formation of the chemical gel, there is no problem as in the prior art. The chemical gel in the form of a dot matrix can also be produced by heat or light, but is preferably produced by a photoinitiated reaction through a mask. As described above, the shape of a chemical gel can be controlled by using a physical gel matrix (a matrix made of a material capable of changing from a gel state to a sol state). Further, when the physical gel matrix system thus produced is placed in an environment where the physical gel undergoes sol transition, the physical gel becomes sol again and becomes fluid. On the other hand, the part where the chemical gel is generated remains in a gel state, that is, a solid state even when the environment is changed due to the chemical bond (covalent bond) between the organic substances. In this state, if the chemical gel is taken out or the sol is washed away, a shape-controlled chemical gel can be obtained.

The solvent used is preferably water in consideration of ease of handling, safety, cost and the like, but basically any solvent can be used as long as it is absorbed in the gel. Specifically, water, alcohols such as methanol and ethanol, ketones such as acetone and methyl ethyl ketone, N
Aprotic polar solvents such as -methylpyrrolidone and N, N-dimethylformamide; halogenated hydrocarbons such as carbon tetrachloride and chloroform; tetrahydrafuran;
Ethers such as diethyl ether; and hydrocarbons such as isopentane and benzene. Regardless of whether water or an organic solvent is used, the temperature at the time of preparing the chemical gel is preferably from the freezing point to the boiling point of the solvent used.

When the liquid is used in a colored state, a dye which does not enter the gel is dispersed in the above-mentioned solvent by using a surfactant or the like as necessary. At this time, the dye to be used is not particularly limited and may be a known one, and the dispersion method or the like may be a usual method, and a known hydrophilic ink, lipophilic ink or the like can be used. Further, an electrolyte salt such as sodium chloride, potassium chloride, calcium chloride, ammonium chloride, and lithium perchlorate may be added to the liquid as needed.

When a temperature change is used to form a physical gel into a sol, any temperature can be basically used. However, in order to keep the physical gel in a solid (gel) state at room temperature (working environment), 40 ° C. It is preferable to make the above. The temperature is more preferably 40 to 80 ° C., and in this range, the energy given for solification is small, and the temperature raising device to be used can be a general-purpose device. The solization temperature of the physical gel is
The temperature is preferably equal to or higher than the temperature at which the chemical gel is produced. With this temperature relationship, the physical gel substantially stays in a solid state when the chemical gel is produced, so that the shape of the chemical gel can be controlled with higher precision.

The formation of a chemical gel in a physical gel can be carried out by heat, light, or the like, but light is preferable from the viewpoint of fine processing. When the temperature is set to a low temperature, it is practically difficult to generate a chemical gel by heat. Therefore, it is preferable to generate a chemical gel by using light that generates less heat. Regarding the formation of a chemical gel in a physical gel matrix (a matrix composed of a material capable of changing from a gel state to a sol state), even if a monomer for chemical gel production reacts with a physical gel constituent material, the chemical Gels can undergo a volume change in response to external stimuli.

Next, a display method and a display device according to the present invention using a gel such as the above-mentioned chemical gel will be described. The display method of the present invention includes a light-transmitting display-side substrate, a non-display-side substrate opposed thereto, a liquid contained between the two substrates, and a gel that expands and contracts (swells and contracts) in response to an external stimulus, Controlling the contact area between the gel on each pixel and the substrate surface in a display method in which the gel expands and contracts to create a state in which the gel is in contact with the substrate surface and a state in which the gel is not in contact with the substrate surface and adjusts the incident light for display. Is used to perform gradation display. Here, the pixel is a minimum unit capable of controlling writing / erasing. In this case, from the state where the gel on the pixel is not in contact with the substrate, a part of the gel first comes into contact with the substrate surface due to the external stimulus, and further, the contact area increases continuously according to the external stimulus. Or, from the state where all of the gel on the pixel is in contact with the substrate surface, the state where the contact area is continuously reduced in response to an external stimulus is preferable, and the external stimulus for expanding and contracting the gel is continuous. The electric field is effective considering the change.

As shown in FIG. 2, a display device using such a display method has a structure in which the gel surface on the side in contact with the display substrate and the display substrate surface are not parallel.
As shown in FIG. 5, when the gel surface on the side contacting the display side substrate and / or the display side substrate surface has an uneven shape, and as shown in FIG. As in the case of at least two types of composite gels having different properties, it is effective to devise a portion other than the gel shape.

FIG. 1 shows an example of a display device using a chemical gel (polymer gel). FIG. 1 shows a method in which a chemical gel and a liquid are arranged between a pair of substrates, at least one of which is transparent. Although a reflective display device that performs display by adjusting contrast of incident light is shown, in the present invention, the control means is not limited to an electric field, and may be a transmissive type as well as a reflective type. However, the present invention is particularly effective for a reflective display device in which the brightness is low and the gradation display is not good in a liquid crystal display or the like.

In this apparatus, for example, when the gel is colored white and the liquid is colored black, or when the gel is colored black and the liquid is colored white, only the solvent can pass through the gel, so that black and white display can be performed. The gel or liquid is not black but RGB (red green blue)
Color display is also possible by coloring in the three primary colors of
Color display is also possible using a color filter.
To color the gel, pigment particles such as carbon and pigment may be immobilized in the gel by adsorption, bonding, or the like. In the present invention, besides such a method, if the display is performed by controlling the contact state of the liquid contained between the display-side substrate and the substrate by the deformation of the gel, such as one using the bending of the gel, Any known method proposed in the past can be used.

As an embodiment for performing the gradation display by controlling the contact area between the gel on each pixel and the substrate surface, the shape of the gel or the substrate as shown in FIGS. In addition, as shown in FIG. 5, there may be mentioned those in which portions other than the gel shape are devised. First, various forms other than those shown in FIGS. 2 and 3 can be considered as a modification of the former gel or the shape of the substrate. As shown in FIG. It is sufficient that the area can be continuously changed depending on the magnitude of the external stimulus.

As a method of processing the gel into various shapes, a method of putting the gel into a mold having a desired shape, synthesizing the gel by using the above-mentioned external stimulus, and taking out the gel from the mold is used, or when the pixel size is small, There is a method in which a photo-crosslinkable monomer is mixed and patterned using photolithography, and then the surface is treated with an acid, an alkali or the like. At this time, if the polymerization rate and the cross-linking rate are controlled by providing a distribution of the amount of irradiation within one pixel plane by devising a photomask, etc., a microgel having a shape as shown in FIGS. Can be. However, the present invention is not limited to these manufacturing methods. FIG.
As shown in Nos. 3 to 3, instead of the gel, the shape of the substrate surface in contact with the gel may be processed. For example, irregularities may be directly formed on the substrate, or layers of various transparent shapes may be provided. May be processed. As a method for providing a new layer having a certain shape, there is a photolithography method using the above-mentioned photoresist.

Next, as a device devising a portion other than the shape of the latter gel, at least two or more types of gels having different responsiveness due to an external stimulus are compounded on one pixel, and the gel is formed within one pixel. A portion that easily expands and contracts and a portion that does not easily expand and contract is formed, and the contact area with the substrate is controlled. As such a form, a gel particle having different responsiveness is uniformly mixed and immobilized on a pixel, or a gel particle having a different responsiveness is unevenly distributed as shown in FIG. Immobilized on the top, irradiating light with the distribution of light intensity in one pixel plane using the same photocrosslinkable monomer, and producing gels with different crosslink rates in one pixel, etc. Any of these can continuously change the contact area between the gel on the pixel and the substrate surface depending on the magnitude of the external stimulus. For external stimuli that deform the gel,
As described above, the temperature, the electric field, the light, the pH, the ion concentration, the solvent composition, and the like can be mentioned. However, considering the driving of the display device, the electric field is practically preferable. An electric field that facilitates a continuous change to achieve a tonal change is preferred.

The substrate needs to be transparent on the display side, and glass, a transparent plastic film or the like is used. In the case of a transmissive display device, a transparent substrate similar to that of the display side is used as the substrate on the side opposite to the display side, and in the case of a reflective display device, the gel itself has a reflection function by whitening the gel. In such a case, a transparent substrate similar to the display side may be used. When the gel does not have a reflection function, Al or SU is used.
A metal plate such as S or a substrate formed by forming a metal film such as Al or Cr on a glass or plastic film to enhance the reflection effect is used. In addition, when the liquid is in contact with the liquid or when a voltage is applied for use as an electrode, it is appropriately selected depending on the liquid to be used and the conditions of the external stimulus. In addition, when the external stimulus is an electric field, an electrode is required along with the substrate, but a transparent electrode is required on the display substrate side,
In ₂ O ₃ , SnO ₂ , ZnO, CdO, TiO ₂ , I
Known materials such as oxide semiconductor thin films such as n ₂ O ₃ —Sn and SnO ₂ —Sb and conductive nitride thin films such as TiN and ZrN are used. On the other hand, the electrodes used on the substrate on the side opposite to the display side include Pt, Au, C
Metal thin films such as u, Al and the like can be mentioned.

Further, according to the present invention, by reducing the wettability between the liquid and the display-side substrate surface in contact with the liquid, when the gel and the substrate come into contact, no liquid remains between the gel and the substrate so that a clear gradation can be obtained. Display becomes possible. Here, the "low wettability" state of the display-side substrate surface in contact with the liquid with respect to the liquid means that the contact angle of the display-side substrate surface in contact with the liquid with the liquid is 50 ° or more in receding contact angle. . Fig. 6
As shown in, the receding contact angle is the angle between the surface of the droplet and the surface of the solid on the solid surface that includes the droplet. The angle can be obtained by enlarging and measuring the angle of the droplet remaining at that time with an optical system.

As a method of reducing the wettability between the display-side substrate surface and the liquid contained between the substrates, the surface of the substrate in contact with the liquid is surface-treated, or a new layer is provided to adjust the wettability. Method, or a method of selecting a combination of a substrate and a solvent. To explain the former in more detail, first, it is conceivable to make the surface of the substrate in contact with the liquid hydrophobic if the liquid to be used is hydrophilic, or hydrophilic if the liquid to be used is lipophilic. Hydrophobicization of the substrate can be achieved, for example, by providing a polymer layer containing a hydrophobic group such as an alkyl group, or by performing a surface treatment using a silane-based or titanium-based coupling agent. Hydrophilization can be achieved by providing a polymer layer containing a hydrophilic group such as a sulfonic acid group, a carboxyl group, a hydroxyl group, an amino group, and a cyano group. Further, it is preferable to carry out an effective liquefaction treatment for both hydrophilic and lipophilic liquids, since the range of selection of the liquids is widened. Such liquefaction can be achieved by, for example, providing a polymer layer having a fluoroalkyl group, a siloxane group, or the like, but is not particularly limited as long as the desired liquefaction property is obtained.

As the polymer having a fluorinated alkyl group,
Fluorinated resins such as polyvinyl fluoride, polyvinylidene fluoride, polytetrafluoroethylene, ethylene-tetrafluoroethylene copolymer, and tetrafluoroethylene-perfluoroalkylvinyl ether copolymer are exemplified. Examples of the polymer having a siloxane group include silicone resins such as dimethyl silicone, methyl phenyl silicone, amino-modified silicone, epoxy-modified, carboxyl-modified, methacryl-modified, phenol-modified and alkyl-modified silicone. . These polymers are dissolved or dispersed in a solvent, and the substrate surface is subjected to liquefaction treatment by immersing the substrate in the solution or dispersion. Other, sol-gel method,
The liquefied layer may be formed by a virosol method, a CVD (chemical vapor deposition) method, a vacuum evaporation method, an ion plating method, or the like.

[0029]

EXAMPLES The present invention will be described below in more detail with reference to examples, but the present invention is not limited to these examples.

Example 1 Two 30 mm × 30 mm quartz substrates were prepared, and a 5% solution of side-top CTX-805A (Asahi Kasei), a thermoplastic resin having a perfluoro structure, was placed on the substrate.
-Solv. The solution was diluted to 0.1% with 100 (Asahi Kasei), spin-coated, and heated at 150 ° C for 2 hours. The two substrates were stacked (inside the processing surface) while two polypropylene spacers having a thickness of 500 μm and 2 mm × 30 mm were placed on both sides of the one substrate treated with the side top, and the two substrates were kept warm. The two sides on which the spacers were installed were clamped and fixed while being superposed. Separately, a liquid prepared by dissolving agar in warm water was prepared, and 0.9 M (mol) of acrylamide and 8 mM (mmol) of N, N'-methylenebisacrylamide were further dissolved in this liquid. After introducing this liquid between the two substrates, 10 ° C.
Upon rapid cooling, the liquid gelled and became an apparent solid. 500 μm wide and 25 m long on the surface of the substrate
A photomask having a slit of m was installed, and after irradiating ultraviolet rays of 253.7 nm with a low-pressure mercury lamp, the clamp was removed and the substrate on one side was removed, and the whole remained gelled. This was immersed in water / acetone, heated to 60 ° C. and left for a while, and then the gel was taken out.
A fibrous chemical gel having a corner and a length of 25 mm could be taken out.

Example 2 A gel was prepared in the same manner as in Example 1 except that acrylamide was replaced with a mixture of acrylamide / sodium acrylate = 15/4. Was completed.

Example 3 The chemical gel obtained in Example 1 was cut into a length of 10 mm and introduced into a glass tube having an inner diameter of 1 mm. Water / acetone =
In 1/1, platinum electrodes were placed on both sides of the glass tube, and when an electric field of 10 V was applied between both platinum electrodes, the chemical gel shrunk and became about 1/10 in size.

Example 4 Striped ITO having a width of 200 μm and a pitch of 240 μm
A 30 mm × 30 mm glass substrate having electrodes was prepared. The liquid used in Example 2 was applied thereon at a thickness of 10 μm, and then cooled to produce a physical gel on a glass substrate with an ITO glass electrode. 200 μm square opening on the surface of the substrate,
After arranging a photomask having a pitch of 240 μm and having 100 × 100 openings so that the openings were on the ITO, ultraviolet rays of 253.7 nm were irradiated with a low-pressure mercury lamp. After the substrate was heated to dissolve and remove the physical gel, observation with an optical microscope confirmed that a 100 μm square chemical gel was formed in a matrix on the ITO.

Example 5 Two 40 mm × 30 mm glass substrates with ITO were prepared. One substrate was prepared by using a 5% solution of side-top CTX-805A (Asahi Kasei), which is a thermoplastic resin having a perfluoro structure, in CT-solv. The solution diluted to 0.1% with 100 (Asahi Kasei) was spin-coated on the ITO surface and heated at 150 ° C. for 2 hours (the ITO portion was left in an area of 10 × 30 mm at the end: for taking out an electrode). Thickness 50
The second substrate is overlapped with the 0 μm, 2 mm × 30 mm polypropylene spacers placed on both sides of the ITO surface on the substrate (inside of the ITO surface; the shape after the two substrates are overlapped is L-shaped) Was kept warm. The two sides on which the spacers were installed were clamped and fixed while being superposed. Separately, a solution prepared by dissolving agar in warm water was prepared, and 0.7 M of acrylamide, 0.2 M of sodium acrylate, and 8 mM of N, N-methylenebisacrylamide were further dissolved in this solution. After the liquid was introduced between the two substrates, the liquid was rapidly cooled to 10 ° C., and the liquid gelled, and became an apparent solid. A photomask having an opening of 1.5 mm square was set on the surface of the substrate, and irradiated with 253.7 nm ultraviolet light from a low-pressure mercury lamp to produce a chemical gel. Without removing the clamp, immersed in black aqueous ink heated to 60 ° C. to sol the physical gel,
The sol liquid and the black ink were replaced. When the clamped substrate was taken out, it was confirmed that only the portion where the chemical gel was prepared at room temperature was transparent and the other portions were black. In this state, the side of the ITO substrate processed with the side top is minus,
When an electric field was applied with the other being positive, the chemical gel shrunk and filled with black ink, and only the black display was no longer visible from the side top side substrate surface.

Example 6 Acrylamide / acrylic acid / vinyl alcohol / titanium oxide (average particle diameter: 0.2 μm) was used in a molar ratio of 659/40.
/ 1/200, and crosslinked by heating from a solution copolymerized by adding ammonium persulfate as an initiator,
Using the mold, a hemispherical acrylic acid-acrylamide copolymer white gel shown in FIG. 7 was prepared. This gel is adhered on a glass substrate on which an ITO electrode has been formed by sputtering, and this substrate is opposed to a glass substrate on which another ITO electrode has been formed at intervals of 5 mm, and the periphery is sealed to form an empty cell. After the cell was filled with the black aqueous ink, the gel was swollen to obtain an evaluation cell as shown in FIG. In this state, the gel in the evaluation cell is not in contact with the ITO electrode on the display-side substrate, and shows a black display.
When a voltage of 1 to 10 V is applied with the electrode of the non-display side substrate set to − and the electrode of the display side substrate set to +, the gel swells and contacts the display side substrate, and a white display of the gel appears from the display side substrate side. At this time, a continuous change in light reflectance due to white display according to the applied voltage was recognized, and it was confirmed that gradation display was possible. Conversely, when a voltage of 1 to 10 V is applied with the electrode of the non-display side substrate set to + and the electrode of the display side substrate set to-, the gel shrinks and the continuity of the light reflectance by white display corresponding to the applied voltage is also increased. It was confirmed that a gradation change was possible.

Example 7 4.8 g of N-isopropylacrylamide, 0.1 g of acrylic acid, 80 m of N, N-methylenebisacrylamide
g, 40 mg of ammonium persulfate were mixed with 60 ml of cold water, 150 μl of tetramethylethylenediamine was added, the mixture was degassed under reduced pressure, copolymerized, and then crosslinked by heating. Next, an acrylic acid-N-isopropylacrylamide copolymer gel having an irregular shape as shown in FIG. 8 was prepared using a mold, and bonded to a glass substrate on which an Al electrode was formed. On the other hand, as a display side substrate, a glass whose surface is subjected to a coupling treatment by applying a 0.5% ethanol solution of γ-aminopropyltrimethoxysilane (Nippon Unicar A1110) and heating at 100 ° C. for 10 minutes is used. A substrate was prepared, opposed to each other in the same manner as in Example 6, filled with a black aqueous ink in the cell, and then swelled with a gel to prepare an evaluation cell as shown in FIG. 8 [The hydrophobic treatment was performed. When the contact angle (receding contact angle) between the surface and the black aqueous ink used in this example was measured, it was 62 °].
In this state, the gel is in contact with the display-side substrate, and the incident light is reflected on the Al electrode surface to show a bright display. The electrode on the non-display side glass substrate functions as a resistance heating layer. When an electric pulse signal (pulse height 5 to 30 V, pulse length 5 msec) with a frequency of 1 kHz was applied to the electrodes of this evaluation cell, the gel shrunk and the continuous change in reflectance by bright display according to the applied pulse voltage. Was confirmed, and it was confirmed that gradation display was possible.

Example 8 4.8 g of acrylamide, 0.2 g of acrylic acid, N, N
A mixture of 100 mg of methylenebisacrylamide, 0.5 g of titanium oxide (average particle size: 0.2 μm) and 80 ml of cold water was mixed on a glass substrate on which an ITO electrode was formed, to a thickness of 10 μm.
m. 300μ on this glass substrate
Irradiation with light from a low-pressure mercury lamp 100W, 2537 ° through a photomask having an m-square dot pattern, 300 μm
An acrylic acid-acrylamide copolymer gel of m-square was prepared. Since the light transmittance on the dot pattern of this photomask is inclined from 50 to 100%, the dot pattern of the polymerized gel has an inclination in the crosslinking ratio, and is shown in FIG. Thus, an aggregate of gels having different stretching behaviors is formed. On the gel thus prepared, a glass substrate on which an ITO electrode was formed with a 15 μm mylar film interposed as a spacer was provided, and the periphery was sealed to form an empty cell. Was satisfied and the gel was swollen to obtain an evaluation cell as shown in FIG. In this state, the gel in the evaluation cell was not in contact with the ITO electrode on the display side substrate, indicating black display. When a voltage of 1 to 10 V is applied with the electrode of + being applied, the gel swells and comes into contact with the display side substrate,
From the display-side substrate side, a white display of the gel appeared. At this time, a continuous change in the reflectance due to the white display according to the applied voltage was recognized, and it was confirmed that gradation display was possible. Furthermore,
Conversely, when a voltage of 1 to 10 V is applied with the electrode of the non-display side substrate set to + and the electrode of the display side substrate set to-, the gel shrinks, and the continuous change in reflectance due to white display corresponding to the applied voltage also occurs. It was confirmed that gradation display was possible.

[0038]

According to the present invention, a chemical gel having a controlled shape and a method for producing the same can be provided. In particular, the present invention 3
In the case where light is used in (1), a fine structure can be efficiently produced, and dissolution of the physical gel due to an increase in heat can be prevented. According to the seventh aspect, it is possible to provide a display device utilizing the characteristics of the chemical gel of the sixth aspect. According to the present inventions 8 to 13, it is possible to provide a gradation display method and apparatus utilizing the expansion and contraction of the gel. In particular, according to the ninth and twelfth aspects of the present invention, it is possible to provide a display method and an apparatus which can be easily driven and make the most of the gradation expression. According to the present inventions 14 to 16, it is possible to provide a display device capable of performing gradation display by simple means. According to the seventeenth aspect, it is possible to provide a display device that can perform gradation display despite being a reflective display device that has low brightness and is difficult to perform gradation display as compared with a transmission display device. Invention 1
According to No. 8, when the gel comes into contact with the display-side substrate, the liquid does not remain on the substrate surface, and a display device capable of more clearly displaying gradation can be provided. According to the present inventions 19 to 20, a display method and a display device utilizing the characteristics of the chemical gel of the present invention 6 can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a reflective display device using a chemical gel.

FIG. 2A is a diagram showing an example in which the gel surface on the side contacting the display side substrate is not parallel to the display side substrate surface. (B) A diagram showing another example in which the gel surface on the side contacting the display side substrate and the display side substrate surface are not parallel. (C) A diagram showing still another example in which the gel surface on the side contacting the display side substrate and the display side substrate surface are not parallel. (D) is a view showing still another example in which the gel surface on the side contacting the display side substrate and the display side substrate surface are not parallel.

FIG. 3 is a diagram showing an example of a case where a gel surface and / or a display-side substrate surface on a side contacting a display-side substrate has an uneven shape. (A) An example in which the gel surface has an uneven shape. (B) An example in which the display side substrate surface has an uneven shape.

FIG. 4 is a diagram showing an example in which a contact area between a gel on a pixel and a display-side substrate surface changes continuously according to the magnitude of an external stimulus. (A) The case without external stimulus is shown. (B) The case of the external stimulus S1 is shown. (C) The case of the external stimulus S2 is shown. (D) The case of the external stimulus S3 is shown.

FIG. 5 is a diagram showing an example in which the gel on each pixel is at least two or more types of composite gels having different responsiveness due to an external stimulus. (A) An example in which two types of gel fine particles are unevenly distributed is shown. (B) Another example in which two types of gel fine particles are unevenly distributed is shown. (C) An example is shown in which the cross-linking ratio of the gel differs in the horizontal direction.

FIG. 6 is a diagram for explaining a contact angle.

FIG. 7 is a diagram showing an evaluation cell using a hemispherical white gel of Example 6. (A) The case where the voltage is OFF is shown. (B) The case where the voltage is ON (1 V) is shown. (C) The case where the voltage is ON (10 V) is shown.

FIG. 8 is a diagram showing an evaluation cell using the uneven gel of Example 7. (A) The case where the electric pulse signal is OFF is shown. (B) The case where the electric pulse signal is ON (5V) is shown. (C) The case where the electric pulse signal is ON (30 V) is shown.

FIG. 9 is a view showing an evaluation cell using a gel having a gradient in the crosslinking rate in Example 8. (A) The case where the voltage is OFF is shown. (B) The case where the voltage is ON (1 V) is shown. (C) The case where the voltage is ON (10 V) is shown.

Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat II (reference) C08F 251/00 C08F 251/00 C08J 3/075 CER C08J 3/075 CER G02B 26/00 G02B 26/00 // C08L 57 : 00 C08L 57:00 (72) Inventor Hiroshi Fujimura 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company (72) Inventor Masakatsu Higa 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Company Ricoh F-term (reference) 2H041 AA21 AB38 AC06 AC07 AZ05 AZ08 4F070 AA02 AE08 BA02 BA07 CB01 GA04 GA06 HA02 HB01 HB05 4J011 HA02 HB14 HB17 PA53 PA69 PB40 PC02 PC08 QA02 QA03 QA06 QA18 BA09 BA12 BA01 BA02

Claims (20)

[Claims] 1. A method for producing a chemical gel, wherein a chemical gel of an arbitrary shape is produced in a physical gel matrix (a matrix made of a material capable of changing from a gel state to a sol state). 2. A system capable of producing a physical gel is prepared, and at a temperature higher than the sol transition temperature of the physical gel, a monomer capable of forming a chemical gel without reacting with the constituent material of the physical gel is formed into a sol together with a solvent. It is added into the system and then cooled to a temperature lower than the sol transition temperature of the physical gel to gel the system, and in this state, the energy for polymerization of the monomer is applied only to a desired position to form a shape-controlled chemical gel. The method for producing a chemical gel according to claim 1, wherein the method is performed. 3. The method for producing a chemical gel according to claim 1, wherein the energy for polymerization is generated by light or heat. 4. The method for producing a chemical gel according to claim 1, wherein the physical gel is formed into a sol after the chemical gel is generated. 5. The method for producing a chemical gel according to claim 1, wherein the chemical gel is generated in a dot matrix on the substrate. 6. A chemical gel produced by the method according to claim 1. 7. A display device using the chemical gel according to claim 6. 8. A display device comprising a light-transmitting display-side substrate, a non-display-side substrate opposed thereto, a liquid contained between the two substrates, and a gel which expands and contracts (swells and contracts) in response to an external stimulus. A display method in which the gel is brought into contact with or not in contact with the display-side substrate surface by expansion and contraction of the gel, and the display is performed by adjusting the incident light. A display method, wherein gradation display is performed by controlling a contact area of a surface. 9. A state in which the gel on a pixel is not in contact with the display-side substrate surface, and then a part of the gel is brought into contact with the display-side substrate surface by an external stimulus. The contact area is continuously reduced in accordance with an external stimulus from a state in which is continuously increased or a state in which all of the gels on the pixels are in contact with the display-side substrate surface. Display method. 10. The display method according to claim 8, wherein the external stimulus for expanding and contracting the gel is an electric field. 11. A light-transmitting display-side substrate, a non-display-side substrate opposed thereto, a liquid contained between the two substrates, and a gel that expands and contracts (swells and shrinks) in response to an external stimulus, The expansion and contraction of the gel creates a state in which the gel is in contact with the display-side substrate surface and a state in which the gel is not in contact with the display-side substrate surface. The display device performs display by adjusting incident light. Wherein the display area is set so that gradation display is performed by controlling the contact area. 12. A state in which the gel on a pixel is not in contact with the display-side substrate surface, and then a part of the gel is brought into contact with the display-side substrate surface by an external stimulus. The contact area is set so as to continuously increase or the contact area decreases continuously in response to an external stimulus from the state where all the gel on the pixel is in contact with the display side substrate surface. The display device according to claim 11, wherein 13. The display device according to claim 11, wherein the external stimulus for expanding and contracting the gel is an electric field. 14. The display device according to claim 1, wherein the surface of the gel on the side in contact with the display-side substrate is not parallel to the surface of the display-side substrate.
14. The display device according to any one of 1 to 13. 15. The display device according to claim 11, wherein the gel surface and / or the display-side substrate surface on the side contacting the display-side substrate have an uneven shape. 16. The display device according to claim 11, wherein the gel on each pixel is at least two or more composite gels having different responsiveness due to an external stimulus. 17. The display device according to claim 11, wherein the display device is a reflection type display device. 18. The liquid crystal display according to claim 11, wherein the wettability of the display-side substrate surface in contact with the liquid with respect to the liquid is low (the contact angle is a receding contact angle of 50 ° or more). Display device. 19. The display method according to claim 8, wherein the chemical gel according to claim 6 is used. 20. The display device according to claim 11, wherein the chemical gel according to claim 6 is used.