JPH06207177A - Method for thermal coagulation under reduced pressure, liquid crystal and laminate produced by using the liquid crystal - Google Patents

Abstract

PURPOSE:To easily obtain a lyotropic liquid crystal having excellent developed color and transparency and free from bubble by heating an isotropic aqueous solution of a linear homopolysaccharide derivative subjected to vacuum deaeration treatment to form a turbid mixture, flocculating and precipitating the solute and removing excess supernatant. CONSTITUTION:A linear homopolysaccharide derivative (e.g. hydroxypropyl cellulose) is incorporated with 0.1wt.% aqueous solution of sodium chloride and thoroughly stirred to form a homogeneous isotropic aqueous solution. The aqueous solution is subjected to vacuum deaeration treatment by allowing the solution to flow down on an inclined plate through a slit in the form of a film under reduced pressure at room temperature. The deaerated solution is heater at 80 deg.C and left standing for 26hr to effect the flocculation and precipitation of the turbid linear homopolysaccharide derivative. The obtained turbid layer is allowed to separate into a turbid flocculated layer and a supernatant layer. After removing the excess supernatant, the system is returned to room temperature to obtain a lyotropic cholesteric liquid crystal. The liquid crystal is sandwiched between substrates and the circumference of the laminate is sealed to obtain a highly transparent liquid crystal laminate exhibiting clear and bright color by dividing a visible light into a reflection light having high saturation and a transmission light having high transparency.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lyotropic cholesteric liquid crystal having excellent liquid crystal characteristics and no bubbles, and a laminate in which the liquid crystals are laminated.

[0002]

2. Description of the Related Art Conventionally, there have been three types of liquid crystals, nematic, smectic, and cholestic, and they have been extensively researched and developed. It is known that the cholesteric liquid crystal shows a rainbow interference color by selectively reflecting visible light due to the helical molecular arrangement, and this coloration reversibly changes depending on temperature. The liquid crystal also includes a lyotropic liquid crystal that takes a liquid crystal phase by mixing a thermotropic liquid crystal that changes from an individual to a liquid crystal by heating and a solvent.

Here, the present invention relates to a lyotropic cholesteric liquid crystal having a solvent effect, not to a nematic liquid crystal used for a thin display and a thermotropic cholesteric liquid crystal used for a temperature indicating material. Further, as the high molecular type, there are liquid crystals in which a linear homopolysaccharide derivative (for example, "hydroxypropyl cellulose) is dissolved at a high concentration and liquid crystals in which polyamino acid esters (for example, poly-γ-benzyl-L-glutamate) are dissolved in a specific solvent. is there. This lyotropic polymer cholesteric liquid crystal is such that the existence of such liquid crystal is basically known, and the interference colors (purple, indigo, blue, green, yellow, orange, and It is known that the color of red also changes reversibly with temperature, and that the temperature range for coloration depends on the concentration, molecular weight and type of solvent.

Therefore, the present inventors have paid attention to the specificity of a water solvent which does not occur in a general organic solvent (eg, acetone, ethanol, propylene glycol, etc.), that is, the hydrophobic bond, and have focused on the linear homopolysaccharide derivative and water. A multi-faceted study of lyotropic cholesteric liquid crystals composed of solvents to propose a method for easily producing liquid crystals free of bubbles and having excellent coloration and transparency, and a laminate and window containing the liquid crystals. Only

First, a method for preventing bubbles from being mixed in the liquid crystal was examined. When a liquid crystal having bubbles was formed into a laminated body, the bubbles moved within the laminated body due to a difference in specific gravity, and as a result, a linear defect was strongly caused in the uniform liquid crystal layer along the trace of the movement. Also, in the field of optical and visual use as in the present invention, the presence of air bubbles should not be a fatal noise. Furthermore, when heated, the solvent vapor is clogged in the bubbles and condensation occurs with cooling,
The density around the bubble portion was uneven and the color was uneven.

However, this liquid crystal, which is a high-concentration aqueous solution obtained by dissolving a linear homopolysaccharide derivative in an aqueous solvent, contains a large number of large and small bubbles when dissolved by a stirring and mixing method, and is a highly viscous liquid, which naturally causes It takes more than one month to stand, and it can be said that it is practically impossible to produce liquid crystal without bubbles by this stirring and mixing method. Therefore, the present inventors examined a rational method conventionally used for defoaming bubbles. For example, it is not effective because the viscosity of the liquid crystal is too high even if it is easy to remove bubbles by a vacuum degassing method, a thin film coating method, etc.
In addition, a surface film was formed to make defoaming difficult, and this film remained as unevenness. Next, a method of naturally defoaming a low-concentration, low-concentration aqueous solution that is in a non-liquid crystal state, and then evaporating water to condense it while preventing the formation of a surface film to a concentration at which it takes a liquid crystal state is very time-consuming It was practically impossible, and the coating also became a problem. Further, it is generally said that there is no rational defoaming method for a high-concentration solution containing a low boiling point solvent. Therefore, as a result of intensive investigations, the present inventors have paid attention to the fact that this liquid crystal is composed of a linear homopolysaccharide derivative and an aqueous solvent, and as a result, have a liquid crystal property superior to that of the stirring and mixing method and can be easily produced without bubbles. The present invention was made possible. Further, it has been made possible to provide a laminate having excellent coloration and transparency by laminating this liquid crystal.

[0007]

The problem to be solved is to provide a lyotropic cholesteric liquid crystal of a high-concentration aqueous solution containing a linear homopolysaccharide derivative and an aqueous solvent, which has excellent coloration and transparency, and has no bubbles. The present invention establishes a method for easily producing a liquid crystal free from the above, and further provides a laminate using the liquid crystal.

[0008]

The present invention has been made to solve the above-mentioned problems, and a linear homopolysaccharide derivative is dissolved in an aqueous solvent to prepare a lyotropic cholesteric liquid crystal. In the method, at least once, a vacuum degassing process was incorporated to cause an isotropic aqueous solution consisting of a linear homopolysaccharide derivative and an aqueous solvent to become a cloudy state by heating to cause phase separation of the linear homopolysaccharide derivative by coagulation sedimentation. In a method for producing a lyotropic cholesteric liquid crystal by dissolving excess linear water to a lyotropic cholesteric liquid crystal, and a linear homopolysaccharide derivative is dissolved in an aqueous solvent to give a lyotropic cholesteric liquid crystal, At least once, vacuum deaeration treatment was incorporated, and an isotropic aqueous solution consisting of a linear homopolysaccharide derivative and an aqueous solvent was heated to become a cloudy state. A lyotropic cholesteric liquid crystal composed of a saccharide derivative phase-separated by coagulation sedimentation to remove excess water, and a lyotropic cholesteric liquid crystal consisting of a linear homopolysaccharide derivative and an aqueous solvent. In a laminate in which at least a part of the substrate is transparent, the isotropic aqueous solution consisting of the linear homopolysaccharide derivative and the water solvent is made at least once into a cloudy state by heating. A laminate comprising a lyotropic cholesteric liquid crystal, wherein the resulting linear homopolysaccharide derivative is phase-separated by coagulation sedimentation to remove excess clean water.

The aqueous solution comprising the linear homopolysaccharide derivative and the aqueous solvent used in the present invention is an isotropic aqueous solution at a concentration of about 50% or less, and easily at a concentration of 20% or less depending on the molecular weight. It could be degassed spontaneously and dissolved uniformly. When this isotropic aqueous solution is heated to 50 ° C. or higher, preferably 60 ° C. or higher, the hydrophobic binding force rapidly increases between the molecules of the linear homopolysaccharide derivative, resulting in a state of white random turbid aggregates. Aggregation and sedimentation caused phase separation. This aggregate is
The higher the temperature, the longer the heating time, and the higher the salt concentration, the stronger the aggregation, and the more the settling volume contracted, resulting in a high concentration state. Next, remove the upper layer water that has been phase separated,
When only the aggregates were returned to room temperature, a lyotropic cholesteric liquid crystal that selectively reflected visible light and colored was obtained. The water solvent here is pure water, tap water, water in which water-soluble additives are dissolved, and the like, and is used in a broad sense.

This coagulation sedimentation is not particularly limited, and a water-soluble electrolyte (for example, sodium chloride, potassium chloride, lithium chloride, sodium nitrate, sodium sulfate,
When calcium chloride, magnesium chloride, sodium benzenesulfonate, sodium 1-hexanesulfonate, etc.) is added to the aqueous solution, the aggregate formation temperature decreases depending on the amount added, causing cloudy aggregation even at room temperature below 50 ° C. Became aggregates. When the phase-separated upper layer water was removed and the temperature was returned to room temperature, the aggregates became liquid crystals containing a water-soluble electrolyte. In this liquid crystal, the phase transition temperature at which the liquid crystal state changed from a colored liquid crystal state to a clouded aggregate state was shifted to a low temperature side as compared with a liquid crystal having no water-soluble electrolyte. The degree of this shift temperature can be controlled by the concentration of the water-soluble electrolyte in the water solvent, and by this method the cloudiness onset temperature of the liquid crystal can be set freely and the phase transition temperature can be easily lowered to the room temperature range. The amount of water-soluble electrolyte added to pure water as a water solvent is 10
% Or less, preferably about 0.1 to 5% by weight. This is not only for laminates that only change color due to the temperature of the natural environment, but also for energy saving,
It is also effective in terms of indoor environment. For example, when a liquid crystal that undergoes a phase transition at 35 ° C is laminated between flat glass (for example, heat-absorbing glass) and used for a window, direct sunlight such as the western sun in the summer may be used. When the window glass was selectively hit, the window glass of the irradiation part was selectively heated by the absorption of solar radiation, and as a result, only the irradiation part was selectively clouded to shield light and prevent glare. The feature of this light shielding is that the stronger the irradiation, the higher the temperature of the irradiation surface and the more opaque it becomes. Further, this liquid crystal did not cause convection due to its high viscosity, and automatically changed automatically due to changes in the environment due to the intensity of direct sunlight, movement of the irradiation surface, and the like. This provides a window with an ideal blind that selectively and automatically shades only the illuminator. Further, it is needless to say that the laminated body using the plate glass with the transparent conductive film as the substrate can electrically control heat generation from transparent to opaque, and therefore, when used as a window, the indoor and outdoor conditions can be limited without depending on the environment. Can provide windows with electronic curtains. As a further application, for example, a fire alarm sensor which can set a cloudy window to a screen for image projection and a photocoupler to the window to catch a cloudy change in the laminate due to an abnormally high temperature in the room, etc., can be widely used.

In the case of a compound that dissolves in water, this coagulation sedimentation is an ultraviolet absorber (for example, 2-hydroxy-4-methoxy-benzophenone-5-sulfonic acid, etc.), a preservative (for example, ethanol, propylene glycol, etc.). ) Etc. or a water-soluble polymer (for example, polyethylene glycol, polypropylene glycol, sodium polyacrylate, etc.) could be added and these compounds could be incorporated at the time of aggregate formation. This can be widely used for modification of liquid crystals.

A method for producing a liquid crystal by making it cloudy by heating and coagulating and precipitating the liquid crystal has been found by the present inventors. However, there is a problem regarding the remaining of bubbles in the liquid crystal, and the coagulating sedimentation method is used. As a result of extensive studies on a method of suppressing the introduction of bubbles into the obtained liquid crystal, the present invention has been accomplished. In particular, the higher the salt concentration of the water solvent, the higher the concentration of the salt, and the higher the concentration of salt. In the present invention, when an aqueous solution containing a linear homopolysaccharide derivative and an aqueous solvent is heated, the gas dissolved in the aqueous solution (for example,
The release of air, nitrogen gas, etc.) occurred at the same time as the aggregation and settling of the linear homopolysaccharide derivative, leaving many small bubbles in the liquid crystal. Therefore, the inventors of the present invention have solved this problem by degassing under reduced pressure on the assumption that the gas dissolved in the aqueous solution is liberated to form bubbles. Since the aqueous solution still containing a large amount of water solvent is degassed under reduced pressure, there is no particular problem such as unevenness due to the film such as defoaming in the liquid crystal state. More effectively by degassing under reduced pressure at room temperature in addition to agitation of the aqueous solution and falling on a thin film on the inclined surface, etc. There is a method for producing liquid crystals by defoaming by depressurizing and then coagulating and precipitating the liquid crystal when small bubbles are generated and in a cloudy dispersed state. Defoaming in this cloudy state is a state in which the linear homopolysaccharide derivative is in the state of dispersion of micro-aggregates, so the viscosity of the aqueous solution drops sharply and becomes a free-flowing state. As a result, a large number of small bubbles generated due to the above were easily floated and the defoaming was promoted. Furthermore, if stirring is also added to this, the agglomeration can be brought into a redispersed state, and there is also an effect of desorbing the bubbles encased in the agglomerate, which was very effective. In addition, the concentration of this aqueous solution has a drawback that the viscosity decreases but the proportion of the water solvent increases, the number of bubbles also increases accordingly, and the volume for aggregation also increases. There is no need to reduce the viscosity by

This degassing under reduced pressure cannot reduce the pressure below the vapor pressure of water at each temperature, which is already known because of the aqueous solvent of the aqueous solution, but it is sufficiently effective for degassing dissolved gas. For example,
At room temperature, a method of degassing under reduced pressure while broadly flowing and dropping the aqueous solution on the inclined surface, and then warming, and at room temperature, stirring so that it is exposed from the lower part, degassing under reduced pressure, and then warming and standing,
A method of dispersing the aggregated cloudy state by stirring at least once in the cloudy state and degassing under reduced pressure and then allowing to warm, a method of degassing under vacuum while stirring with stirring in a cloudy state, and leaving to cloudy and dispersed There are a method of degassing under reduced pressure while flowing and dropping the aqueous solution over a wide slope on a slanted surface, followed by heating, and a method of centrifuging and aggregating the degassed aqueous solution in a cloudy state by centrifugation. It should be noted that this stirring also has an effect of causing sedimentation evenly in a lower portion without causing unevenness in aggregation and sedimentation. The temperature of warming in the cloudy state may be a temperature near the boiling point of about 95 ° C. when the water solvent is pure water (for example, purified water according to the pharmacopoeia), and as the salt concentration increases, the linear homopolysaccharide derivative It is better to lower the temperature because the aggregation will be stronger. The higher the temperature, the higher the molecular weight, and the higher the salt concentration of the water solvent, the stronger the cohesive force, and the shorter the time for coagulating sedimentation. With the salt-added water solvent, an aggregate which becomes a liquid crystal was obtained by standing for 10 minutes to 50 hours after reaching the aggregation temperature. Preferably centrifugation is used without addition of salt. It should be noted that the rapid formation of aggregates only by heating is not good for homogenization, and it is advisable to reduce the step heating temperature and the aggregation temperature to a certain level for aggregation to a liquid crystal concentration.

Further, the white turbid aggregates in the heated state are in a non-liquid crystal state and can be taken out by sliding the wall without sticking to the wall of the container, and have a low viscosity because of the non-liquid crystal state. It was This feature was very important to prevent air bubbles from being mixed in during handling. For example, this non-adhesiveness is due to the fact that the aqueous solution is heated to cause the aggregates to settle down to a lower part continuously, and the pump (for example, Snake pump,
It was effective to continuously draw it out from the lower part with a gear pump, etc., and to pass it through a static mixer to make the concentration uniform if necessary, and then push it out from the slit and continuously supply it to the next step. In this next step, in order to prevent surface drying of the extruded agglomerates, under saturated steam or water solvent, the agglomerates are set without entraining bubbles in the substrate, and then the counter substrate is turned into agglomerates from above. It was possible to easily stack without bubbles by applying pressure while contacting the sides with a rubber plate while preventing them from leaking. In this way, if the state of a cloudy aggregate is taken, it has a low viscosity and is useful for the laminating step, and this low viscosity characteristic is important especially for laminating with a large substrate. Generally, a cloudy agglomerate is sandwiched between substrates and spread under pressure.
The thickness may be about m to 2 m. In addition, for example, it was possible to inject a cloudy agglomerate into a gap by pressurizing it into a gap such as a hollow glass tube or a deformed laminate having a gap, but it is impossible in a liquid crystal state because of high viscosity. It was Regarding the quality of the laminate, the cloudy aggregate was isotropic, and the flow orientation that appeared when the liquid crystal was expanded under pressure was very small, and a laminate having a liquid crystal in a monodomain state could be obtained. . This method was very simple and had a great effect in obtaining a monodomain state without requiring alignment treatment or the like. As a matter of course, it was possible to pull out the liquid crystal from the lower part in the liquid crystal state at room temperature and stack the liquid crystal at room temperature without involving air bubbles.

More importantly, the liquid crystal laminate according to the present invention has a very good light scattering selectivity which is directly related to the color saturation, which is the essence of liquid crystal characteristics, that is, the color purity. The liquid crystal obtained by the mixing method exhibited a clearer bright coloration. Therefore, stable and inexpensive cellulose is selected as an example of the linear homopolysaccharide, and hydroxypropyl cellulose obtained by reacting this cellulose with propylene oxide is selected, but it is not particularly limited thereto, and it is mixed with water. Any linear homopolysaccharide derivative having a liquid crystal state may be used, and a cellulose derivative is also preferable from the viewpoint of stability. A lyotropic cholesteric liquid crystal composed of hydroxypropyl cellulose and water exhibits durability, vivid coloration, sufficient light-shielding property due to white turbid aggregation, is almost nontoxic, and is important from the viewpoint of safety. As a typical example of a linear homopolysaccharide derivative, hydroxypropyl cellulose (average polymerization degree of 175, viscosity of 2% aqueous solution at 20 ° C. is 8.5 cps, hydroxypropyl group is 62.4).
%), And a liquid crystal consisting of this hydroxypropyl cellulose and a 0.1% by weight aqueous solution as a water solvent is laminated between plate glasses, and visible light is selected by using J-720 circular dichroism dispersion meter J-720 type. The state of scattering was measured at room temperature. As a result, the half-wave value of the liquid crystal laminate by the coagulation sedimentation method of the present invention is 17 nm. The value is half or less of the half-wave value (35 nm) of the liquid crystal laminate by the simple mixing method, and it is clearly seen that the laminate according to the present invention has excellent selective scattering characteristics. As a result, the laminate of the present invention splits visible light into reflected light with high saturation and transmitted light with high transparency, and exhibited clear bright coloration and transparency with high transparency. As a result, when the laminated body using the liquid crystal according to the present invention is used as a window, a bright view outside the room in the daytime does not cause particularly blurring or clouding, and good transparency can be obtained. It was not possible by law. Moreover, when this window was seen from a bright room, it showed a clear and bright coloration. The reason for this is considered to be that the liquid crystal prepared by the coagulation-sedimentation method has a uniform molecular alignment order because it forms a molecular coagulation from a thin aqueous solution having a low viscosity, and forms a defect-free monodomain.

The shape of the laminated body can be freely selected, and the size is not particularly limited, and it is sufficient that the laminated body has a transparent portion in which the inside can be directly viewed. The substrate may be glass, resin, metal, ceramics, etc. without particular limitation. If necessary, the thickness of the liquid crystal layer may be controlled by a spacer. It is more preferable that the spacer is transparent and has its specific gravity and refractive index matched with that of the liquid crystal. As a method for producing the laminated body, the aggregate was sandwiched between the substrates in an atmosphere of saturated steam and pressed to obtain a desired thickness, and a uniform layered body was obtained without forming a dry film. As a result, the liquid crystal could be easily and surely laminated between the substrates without the inclusion of bubbles. After that, the outer circumference may be wiped off and the outer circumference may be sealed with a sealant (for example, an adhesive-attached aluminum tape or the like). Further, in order to completely seal the outer circumference in order to suppress water evaporation, it is advisable to seal and adhere the four sides of the outer circumference with a U-shaped metal frame having a room temperature curable heat resistant resin. In addition, this laminated body,
Can be widely used for windows, tables, advertising lights, tiles, bathtubs, drinking water, etc.

In particular, by using this laminate for a window, an excellent window can be obtained. Examples of the windows include windows of ordinary buildings, vehicles such as automobiles and railway cars, and windows of transport planes such as aircraft and elevators. Of course, this window has a broad meaning, and includes a door with a window, a partition, etc., as well as a transparent glass door, a screen, a wall, etc.

The main subject of the present invention is a lyotropic cholesteric liquid crystal of a high-concentration aqueous solution containing a linear homopolysaccharide derivative and an aqueous solvent, and a liquid crystal having excellent coloration and transparency and having no bubbles can be simply used. The description of the liquid crystal system will be omitted because it is a method of producing and a laminated body using the liquid crystal. Here, hydroxypropylcellulose obtained by reacting cellulose with propylene oxide was selected as a representative example of the linear homopolysaccharide derivative, but the invention is not particularly limited thereto. In addition, as the proportion of hydroxypropyl groups increased, coagulation and sedimentation became easier. Further, as the molecular weight of hydroxypropyl cellulose tends to decrease, the cohesiveness tends to decrease, and addition of a salt is effective for preventing this. Hydroxypropyl cellulose has a hydroxypropyl group ether-bonded to the main chain skeleton of cellulose and has very strong weather resistance and heat resistance, and can be used in places such as windows that are exposed to direct sunlight and under severe environmental conditions. It is non-toxic and important in terms of safety, and can be widely used for consumer products.

[0019]

【Example】

Example 1 Hydroxypropyl cellulose (average polymerization degree of 175,
To 50 parts by weight of a 2% aqueous solution having a viscosity at 20 ° C. of 8.5 cps and a hydroxypropyl group of 62.4%), 250 parts by weight of a 0.1% by weight sodium chloride aqueous solvent was added and sufficiently stirred and mixed to form a uniform aqueous solution. . At room temperature, this aqueous solution was made to flow from a slit to a tilted plate of about 30 degrees under a reduced pressure of 720 mmHg under a reduced pressure of 720 mmHg to thoroughly degas it, and then promptly at 80 ° C.
It was left to stand in the atmosphere of No. 26 for 26 hours to be sedimented to separate into a cloudy aggregate layer and a water layer. The clean water was removed and the temperature was returned to room temperature to obtain a lyotropic cholesteric liquid crystal free from bubbles. This liquid crystal having a thickness of 0.2 mm was laminated between plate glasses, and the state of selective scattering of visible light was measured at room temperature by using JASCO's circular dichroism dispersion meter J-720 type. The half-wave value of the scattering spectrum was 17 nm. Of course, it was also possible to use it in an aqueous solution that had been heated and had become cloudy.

[0020]

【Example】

Example 2 As a reference example, without degassing under reduced pressure, the bubble-free homogeneous aqueous solution of Example 1 was allowed to stand in an atmosphere of 80 ° C. for 26 hours to settle to separate into a cloudy agglomerated layer and a water layer. The clean water was removed and the temperature was returned to room temperature to give a lyotropic cholesteric liquid crystal. As a result, the half-wave value of the selective scattering spectrum was good, but easily visible small bubbles with a diameter of about 0.1 to 0.3 mm remained in the liquid crystal layer almost innumerably. . It should be noted that many small bubbles were already observed when the temperature of the aqueous solution was about 45 ° C. under normal pressure.

[0021]

【Example】

Example 3 Hydroxypropyl cellulose (average degree of polymerization: 175,
To 50 parts by weight of a 2% aqueous solution having a viscosity at 20 ° C. of 8.5 cps and a hydroxypropyl group of 62.4%), 250 parts by weight of a 0.1% by weight sodium chloride aqueous solvent was added and sufficiently stirred and mixed to form a uniform aqueous solution. . This aqueous solution has an inner diameter of 30 m
20 ml in a sample tube of m and put in an atmosphere of 80 ° C.
After leaving it for a minute, it is stirred with a glass rod to form a uniformly turbid aqueous dispersion solution, which is then degassed under a reduced pressure of about 720 mmHg at 80 ° C., and then allowed to stand at 80 ° C. for 26 hours for aggregation and sedimentation. Water was removed to obtain a lyotropic cholesteric liquid crystal without bubbles. The half-wave value of the selective scattering spectrum obtained the same result as in Example 1.

[0022]

【Example】

Example 4 The dispersed aqueous solution was degassed in the same manner as in Example 3, and then 80
After leaving it in the atmosphere of 2 ℃ for 2 hours, the aggregated and settled white turbid layer and the water layer are about half and half and centrifuged at 3000 rpm for 6 minutes to quickly settle and remove the water to remove uniform bubbles. A lyotropic cholesteric liquid crystal was easily obtained. The half-wave value of the selective scattering spectrum obtained the same result as in Example 1.

[0023]

【Example】

Example 5 Hydroxypropyl cellulose (average polymerization degree of 175,
Viscosity of 2% aqueous solution at 20 ° C. is 8.5 cps, hydroxypropyl group is 62.4%) 3 parts by weight in 50 parts by weight
350 parts by weight of an aqueous solution of sodium chloride was added and sufficiently stirred and mixed to obtain a uniform aqueous solution. Take 1 liter in a container that can be agitated under reduced pressure, depressurize at a reduced pressure of about 720 mmHg for 6 hours while stirring at 48 ° C. so that it can flow out from the central part, then stop stirring and aggregate and settle at 60 ° C. for 2 hours. A lyotropic cholesteric liquid crystal having no bubbles and capable of sufficiently clouding and shading at 40 ° C. due to a salt effect was obtained.

[0024]

【Example】

Example 6 A 1 mm square 6 mm thick glass plate was dipped in a 70 ° C. sodium chloride aqueous solution, and the cloudy agglomerated layer obtained by the same method as in Example 1 was poured on the substrate together with the supernatant liquid, and as a counter substrate thereon. Beads having a diameter of 0.2 mm at a pitch of 5 cm on a 6 mm thick glass plate of 1 m square (dried and fixed using the same hydroxypropylcellulose aqueous solution as in Example 1).
Stack the substrates that have the spacers as spacers, and open the both ends of each side as escape holes for water by about 5 mm and apply a rubber plate,
0.2 mm thick by spreading water with low viscosity preferentially from the four corners between the glass substrates while spreading the isotropic agglomerates under pressure while preventing the agglomerates from leaking from the sides. The liquid crystal layer of No. 1 could be formed without air bubbles. Then, this laminated body was naturally cooled to room temperature and the outer periphery was wiped and dried. Furthermore, the outer circumference 4
The sides were sealed with a U-shaped aluminum frame having a room temperature curing type epoxy resin. As a result, a highly transparent 1 m square laminate showing a colored pattern due to the difference in density and having no bubbles was obtained.

[0025]

INDUSTRIAL APPLICABILITY As described above, the present invention is a lyotropic cholesteric liquid crystal of a high-concentration aqueous solution containing a linear homopolysaccharide derivative and an aqueous solvent, which has excellent coloration and transparency and is free of bubbles. A method for easily producing liquid crystals was obtained. The laminate having the liquid crystal of the present invention splits visible light into reflected light with high saturation and transmitted light with high transparency, and showed clear bright coloration and transparency with high transparency. As a result, when the laminated body using the liquid crystal according to the present invention is used as a window, a bright view outside the room during the daytime does not cause particular blurring or clouding, and good transparency can be obtained. The window showed a clear, bright coloration. In addition, we were able to provide a window with an ideal blind in which only the irradiation surface of direct sunlight became cloudy selectively and the light was automatically changed.

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Claims (8)

[Claims] 1. A method for producing a lyotropic cholesteric liquid crystal by dissolving a linear homopolysaccharide derivative in a water solvent, wherein a vacuum degassing process is incorporated at least once to remove the linear homopolysaccharide derivative and the water solvent. Which is characterized by producing a lyotropic cholesteric liquid crystal by phase separation of a linear homopolysaccharide derivative which has become cloudy by heating an isotropic aqueous solution by coagulation sedimentation to remove excess tap water. Method. 2. The production method according to claim 1, wherein the turbid state is stirred at least once in the turbid state to disperse the turbid state which has been aggregated, degassed under reduced pressure, and then allowed to aggregate and settle. 3. The method according to claim 3, wherein deaeration under reduced pressure is carried out in a cloudy state while stirring, and then the mixture is allowed to aggregate and settle. 4. The method according to claim 1, wherein degassing is carried out under reduced pressure while flowing and dropping the liquid film over a wide inclined surface. 5. The method according to claim 1, wherein the phase separation of the coagulation sedimentation is performed by centrifugation. 6. The water is removed by continuously removing the aggregates that have aggregated and settled from the lower layer portion.
Or the manufacturing method of Claim 2. 7. A method for producing a lyotropic cholesteric liquid crystal by dissolving a linear homopolysaccharide derivative in a water solvent, which comprises a linear homopolysaccharide derivative and an aqueous solvent at least by incorporating reduced pressure deaeration treatment, etc. A lyotropic cholesteric liquid crystal characterized in that a linear homopolysaccharide derivative, which has become cloudy by heating an isotropic aqueous solution, is phase-separated by coagulation sedimentation to remove excess clean water. 8. A laminate in which a lyotropic cholesteric liquid crystal comprising a linear homopolysaccharide derivative and an aqueous solvent is laminated on a substrate, and at least a part of the substrate is transparent, at least under reduced pressure degassing treatment is incorporated. Characterized by removing excess tap water by phase separation of a linear homopolysaccharide derivative that has become cloudy by heating an isotropic aqueous solution consisting of the linear homopolysaccharide derivative and an aqueous solvent by coagulation sedimentation And a lyotropic cholesteric liquid crystal.