JPH03181918A - Dimmer element - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a light control element that adjusts light transmittance.

[Prior Art] Conventionally, a cell is composed of a pair of transparent substrates in which a pair of transparent electrode layers are formed on opposing inner wall surfaces and the periphery is sealed via a spacer, and a dispersion medium is housed in the cell. and a suspension of fine polarizing substances dispersed in the dispersion medium are known.

In a light control element, when no voltage is applied, a polarizing substance is randomly oriented and dispersed in a suspension while undergoing Brownian motion. Therefore, visible light incident on the dimmer is absorbed and the dimmer appears dark. Further, when a voltage is applied, the polarizing substances in the suspension are aligned in a direction perpendicular to the transparent substrate forming the cell (the direction of application).

Therefore, the incident visible light is transmitted between the oriented surfaces and the dimming element appears bright and transparent.

Perhalides of alkaloids have been known for a long time as substances exhibiting polarization properties used in such light control elements. In order to orient this alkaloid perhalide with good transparency upon application of voltage and to effectively act as the polarizing substance, it is necessary to synthesize it into a needle-like, rod-like, or thin platelet-like crystal shape.

As a method for synthesizing needle-like crystals of this polarizing substance, for example,
Synthesis of periodide of dihydrocinchonidine sulfate carried out in the presence of nitrocellulose (JP-A-53-14)
No. 4893).

Dihydrocinchonidine, which is an unsaturated organic substance reduced by hydrogenation, is reacted with sulfuric acid to form a salt, dissolved in a suitable liquid medium, and then in the presence of nitrocellulose, an effective amount of iodine and This is a method of synthesizing the above-mentioned periodide by reacting it with calcium iodide. The nitrocellulose described above is used as a protective colloid that binds to a polarizing substance to prevent aggregation of the polarizing substance and maintain a stable suspension.

Also, a method for synthesizing periodide of quinine sulfate in the presence of iron ions (Japanese Patent Publication No. 48-20560)
There is also.

[Problems to be Solved by the Invention] However, since all of the above synthetic methods require a large number of reaction raw materials, unreacted substances such as iodine and dihydrocinchonidine sulfate, or calcium sulfate, etc. are present in the resulting product. By-products are present. When this product is used as a polarizing substance for a light control element, impurities such as the above-mentioned unreacted substances and by-products will dissolve in the suspension and become ionic fractions, which will cause overcurrent when voltage is applied. becomes. Therefore, power consumption increases. Further, since the load on the battery becomes large, it is difficult to use it for automobiles.

Furthermore, if nitrocellulose is excessive and liberated in the suspension, the nitrocellulose will naturally decompose even at room temperature and generate nitrogen oxide, and the polarizing substance will deteriorate due to this nitrogen oxide.

That is, nitrogen dioxide, which is automatically oxidized from nitrogen oxide by a small amount of oxygen, reacts with water produced by the decomposition of nitrocellulose or with water in the outside world to become nitric acid and nitrous acid. These acids decompose the polarizing substance. Note that the decomposition of nitrocellulose is also promoted by the presence of impurities, nitrogen dioxide, acids, alkalis, etc., as well as light and heat. For this reason,
The heat resistance and weather resistance as a light control element are poor, and the durability is also poor.

The present invention has been made in view of the above circumstances, and a technical problem to be solved is to provide a light control element that can be driven with low current and has improved durability.

[Means for Solving the Problems] The present invention provides a suspension comprising a structural element having an electric field applying means, a dispersion medium housed within the structural element, and a fine polarizing substance dispersed in the dispersion medium. In the light control element, the polarizing substance is synthesized in the presence of nitrocellulose and is mainly composed of a perhalide of an organic compound having an aryl group and a saturated branched chain connected to the aryl group, and has electrical resistance. It is characterized in that impurities that reduce the amount of nitrocellulose and excess nitrocellulose are separated and removed.

In addition to the cells described in the prior art, a large number of transparent microcapsules embedded in a transparent sheet-like resin base can be used as the structural element.

The cell can be constituted by a pair of transparent base materials in which a pair of transparent electrode layers serving as electric field applying means are formed on opposing inner wall surfaces, and the periphery of the cell is sealed via a spacer.

Glass, resin film, resin plate, etc. can be used as the transparent base material. When using resin, use polyester (PET,
PC>, a material with excellent transparency such as acrylic (PMMA) is used.

For the transparent electrode, oxide thin films such as ITO (In203 ・5nO2), tin oxide (SnO2), and indium oxide (InzO3) can be used.
It is also possible to use a thin film having a thickness such that metals such as T, etc. exhibit transparency. This transparent electrode can be easily formed by, for example, a PVD method such as vapor deposition.

The microcapsules can be produced by a conventional method such as dispersing a mixture of a polarizing substance and a dispersion medium in water and polyvinyl alcohol to form an emulsion, as disclosed in Japanese Patent Application No. 153548 filed by the present applicant. It is created by a thin transparent resin layer (for example, the thickness is 50~
500 μm> are used by being embedded in large numbers.

A suspension consisting of a dispersion medium and a fine polarizing substance dispersed in the dispersion medium is sealed within the structural element.

The dispersion medium constituting this suspension is not particularly limited as long as it disperses the polarizing substance to form a stable suspension, including water,
Organic solvents can be used. Note that when a liquid with relatively high electrical resistance is used as a dispersion medium, the orientation of the polarizing substance when voltage is applied is improved, and power consumption can be reduced.

Typical examples of the organic solvent include aliphatic esters, aromatic esters, aliphatic halides, and the like. for example,
Examples include tolyl acetate, octyl acetate, dioctyl phthalate, didecyl phthalate, and ditridecyl phthalate. These may be used alone or in combination, or may be mixed with other inert solvents. An example thereof is a mixed solvent of ditridecyl phthalate and n-dodecane.

Note that a dispersion stabilizer can also be used to stabilize the dispersion state. The dispersion stabilizer may be a copolymer of acrylic ester, fumaric ester, fumaric acid, or the like. This dispersion stabilizer is, for example, 3.5.5
- Copolymer of trimethylhexyl acrylate/bis-2-ethylhexyl fumarate/2-hydroxypropyl acrylate/fumaric acid or bis-2-ethylhexyl fumarate/3.5.5-trimethylhexyl acrylate/vinylidene chloride/Methacon Examples include acid copolymers.

The polarizing substance constituting the suspension is mainly composed of an aryl group and a perhalide of an organic compound having a saturated branched chain connected to the aryl group, and contains impurities, that is, impurities that reduce electrical resistance. , excess nitrocellulose is separated and removed.

The perhalide of the above-mentioned organic compound can be produced, for example, as follows. First, the unsaturated organic compound is reduced, for example by hydrogenation. The resulting saturated organic compound is reacted with a suitable acid to form a salt, dissolved in a suitable liquid medium, and then reacted with an effective amount of halogen atoms and halides in the presence of nitrocellulose to form a perhalogen. Make it into a monster. The nitrocellulose described above is used as a protective colloid that binds to a polarizing substance to prevent aggregation of the polarizing substance and maintain a stable suspension.

Centrifugation, dialysis, etc. can be employed as means for separating and removing the above-mentioned impurities and unnecessary substances.

The solvent used to separate and remove the above impurities is:
It is preferable to use one that is inert to the polarizing substance and has a specific gravity different from that of the polarizing substance. For example, ester organic solvents such as p-cresyl acetate (tolyl acetate), isopentyl acetate, phenyl acetate, dioctyl phthalate, diisodecyl phthalate, and ditridecyl phthalate can be mentioned. These solvents can be used alone or mixed with each other or with other solvents.

The impurities mentioned above are ionic components that cause overcurrent when voltage is applied, and those that degrade polarizing substances, such as unreacted substances, by-products, excess nitrocellulose, etc. .

When the polarizing substance is an alkaloid perhalide, the content of the nitrocellulose in the suspension is 5 to 5 parts by weight per 100 parts by weight of the alkaloid perhalide.
Preferably it is 30 parts by weight, optimally 20 parts by weight. If the content is less than 5 parts by weight, the amount of coordination of nitrocellulose to the polarizing substance will be small, and the suspension will not have a clear blue color. Moreover, when the content is more than 30 parts by weight, coordination with the polarizing substance becomes saturated, and excess nitrocellulose dissolves in the suspension and becomes liberated. As described above, this liberated nitrocellulose naturally decomposes at room temperature to generate nitrogen oxide.

This nitrogen oxide is oxidized to nitrogen dioxide by a trace amount of oxygen, and reacts with water to become nitric acid and nitrous acid, thereby degrading the polarizing material.

When the polarizing substance is, for example, an alkaloid perhalide, the content of the ionic component in the suspension is preferably 10 parts by weight or less per 100 parts by weight of the alkaloid perhalide.

When the content is more than 10 parts by weight, the amount of overcurrent when voltage is applied increases. For example, when an AC voltage of 50V is applied to a cell with a cell thickness of 100 μm, if the content of the ionic component is more than 10 parts by weight, a current of 1 mA/Cm2 or more will flow, which is excessive for automobile batteries etc. It can be a burden.

[Function] The light control element of the present invention has 1. When no voltage is applied to the voltage applying means, the polarizing substance is randomly oriented and absorbs visible light, so the dimming element appears dark. On the other hand, when a voltage is applied to the voltage applying means, the polarizing substance is regulated by the electric field and oriented in a direction parallel to the voltage applying direction, and visible light is transmitted in this direction, so the light control element is transparent and bright. appear.

In the light control element of the present invention, impurities present in the polarizing substance are separated and removed using an ester-based organic solvent, so that excess nitrocellulose, ionic components, etc. are not released into the suspension. do not have. Therefore, it is possible to prevent deterioration of the polarizing substance due to acid 1 generated by decomposition of nitrocellulose. Moreover, overcurrent during voltage application, which occurs due to the presence of ionic components, can be prevented.

[Example] The present invention will be specifically explained below using Examples.

(Example 1) Water 168.0 in a 500CG Erlenmeyer flask
CI, 97% sulfuric acid 15. OQ, cinchonidine 40.0g
, and 150 cc of a 2% aqueous solution of palladium chloride was injected with stirring using a magnetic stirrer.

The air in the flask was replaced with hydrogen introduced under pressure at 80-100 cm of water. The hydrogenation reaction proceeded slowly until palladium was completely reduced, and the mixture was thoroughly stirred during this time.

The reaction product was filtered off from the palladium and diluted with water to 600 cc with stirring. Approximately 25 Q of 50% caustic soda was rapidly added to the reaction product with sufficient stirring, and the mixture
I made it. Stirring was then continued for 10 minutes. The amorphous crystals of dihydrocinchonidine were vacuum filtered and washed thoroughly with water. The product 2 was then tamped to remove as much water as possible and then spread out to dry in the air. The product was crystallized from 50% ethanol water at 0-2°C for 8-10 hours. The product was filtered, washed with a minimum amount of 50% cold ethanol water, and dried at 82° C. for 4 hours to obtain dihydrocinchonidine.

Dihydrocinchonidine 3.06g, 97% sulfuric acid 0.69
g, 2-ethoxyethanol 20.0 g, water 10. OQ
solution and nitrocellulose 14°17(j, 2-ethoxyethanol 28.35Q.

Tricresyl phosphate 10. The Oa solution was mixed and stirred well. Calcium iodide 0.49
CI, iodine 3.04CI, n-propatool 12.0
A solution of g, tricresyl phosphate 35, and OQ was added all at once and stirred vigorously.

After stirring for 30 minutes, the mixture was spread on a glass plate to remove volatile components.

10g of this paste substance was converted into tolyl acetate 150Q.
A suspension was prepared by dispersing the mixture well using ultrasonic waves.

3 Then, transfer this suspension to a Hitachi high-speed refrigerated centrifuge type 5C.
Using R20B, RPR-20-20-2, 1so per minute
Centrifugation was performed at oo rotation (centrifugal acceleration, 39917 g) for 30 minutes, and the supernatant liquid was discarded.

The same treatment of dispersion in tolyl acetate and centrifugation was repeated 5 times for the precipitate.

Finally, centrifugation was performed at 2000 revolutions per minute (centrifugal acceleration, 492q) for 5 minutes, and the precipitate was discarded to obtain the final target purified suspension. Quantitative analysis of this purified suspension revealed that dihydrocinchonidine i acid periodide was 100%
The total weight of dissolved components of unreacted iodine, calcium sulfate and dihydrocinchonidine sulfate periodide was 1.2 parts by weight. Moreover, this purified suspension exhibited a bright blue color.

This purified suspension was sealed in a cell with a cell thickness of 100 μm to produce a light control element of Example 1. When an AC voltage with an RMS value of 50 V and 1 kHz was applied to this light control element, the voltage was 0.1
A current of mA/cm2 was applied, and the color changed from blue to transparent.

4 (Example 2) 1゜q of the paste-like material prepared in the same manner as in Example] was placed in isopentyl acetate 150C] and thoroughly dispersed with ultrasonic waves to prepare a suspension.

This suspension was placed in a dialysis tube and left in isopendel acetate for 24 hours to obtain the final target product, a purified suspension. Furthermore, when this purified suspension was quantitatively analyzed,
The total weight of unreacted iodine, calcium sulfate, and dissolved components of dihydrocinchonidine sulfate periodide was 3.1 parts by weight relative to 100 parts by weight of dihydrocinchonidine sulfate periodide.

This purified suspension was sealed in a cell similar to that of Example 1 to produce a light control element of Example 2. When the same voltage as in Example 1 was applied to this light control element, a current of 0°22 mA/cm2 flowed and the color changed from blue to transparent.

The light control elements of Examples 1 and 2 above use purified suspensions that have been subjected to centrifugation and dialysis, respectively. That is, since ionic impurities were removed from all of the polarizing substances in the light control element of Example 1.2, the current flow during voltage application was reduced.

Therefore, the light control element of Example 1.2 consumes less power. In addition, since components that do not contribute to color tone have been removed, it exhibits a bright blue color and has increased transparency when voltage is applied.

(Comparative Example 1) A paste-like substance 10q prepared in the same manner as in Example 1 was placed in tolyl acetate 150C] and dispersed well using ultrasonic waves to prepare a suspension III. Quantitative analysis of this suspension revealed that dihydrocinchonidine sulfate periodide 1
The total weight of the dissolved components of unreacted iodine, calcium Ta acid, and dihydrocinchonidine fA acid periodide was 20 parts by weight.

Comparative Example 1: This suspension was sealed in the same cell as in Example 1.
A light control device was manufactured. When a voltage similar to that in Example] was applied to this light control element, a current of 1.2 mA/cm2 flowed, and the color changed from blue to transparent.

6 (Example 3) A paste-like substance 10q prepared in the same manner as in Example 1 was placed in tolylacetate 150Q and well dispersed using ultrasonic waves to prepare a suspension.

Then, this suspension was transferred to a Hitachi high-speed refrigerated centrifuge type 5C.
R20B, RPR-2C) - 20 - 18 per minute
Centrifugation was performed for 30 minutes at 000 rpm (centrifuge mouth speed, 399]7cx), and the supernatant was discarded.

The same treatment of dispersion in tolyl acetate and centrifugation of the precipitate was repeated seven times until there was no nitrocellulose in the supernatant. In addition, quantitative analysis of the final precipitate revealed that dihydrocinchonidine sulfate periodide 1
00 parts by weight, 20 parts by weight of nitrocellulose was contained.

The precipitate thus obtained was dispersed again using ultrasonic waves in 60 cx of a mixed solution of 3 parts of ditridecyl phthalate and 2 parts of dodecane to obtain a purified suspension, which was the final target product.

This purified suspension was sealed in the same cell as in Example] to produce a light control element of Example 3. Even if this photochromic element]7 was heated in an open state at 85°C, the purified suspension did not change color. Furthermore, when a voltage similar to that in Example 1 was applied to this light control element, it changed from bright blue to transparent very quickly.

In the light control element of Example 3, there is no free cell loss in the suspension due to the repeated centrifugation treatment. That is, nitric acid and nitrous acid, which are produced by decomposition of nitrocellulose and degrade the polarizing material, are not present in the suspension. Therefore, the durability of the light control element of Example 3 was improved.

Also, 111. Since nitrocellulose was not present in the suspension, the viscosity of the suspension was reduced, which improved the responsiveness upon voltage application.

(Comparative Example 2) Example of the suspension obtained in Example 3 before centrifugation]
A light control element of Comparative Example 2 was manufactured by enclosing it in a cell similar to the above. When this light control element was left in an oven at 85°C, the color changed from blue to yellow in 2 hours. Quantitative analysis of the above suspension revealed that 46 parts by weight of nitrocellulose was contained per 1008 parts by weight of dihydrosinic herring sulfate periodide.

[Effects of the Invention] As detailed above, in the light control element of the present invention, impurities and unnecessary substances in the polarizing substance are separated and removed using an ester solvent. That is, in the suspension of the light control element of the present invention, there are no ionic impurities that cause overcurrent when a voltage is applied, or free ditocellulose that causes deterioration of the polarizing substance.

Therefore, the light control element of the present invention consumes less power and has high durability.

Further, since components unnecessary for color tone are removed, the light control element of the present invention has a low degree of cloudiness.

Claims (1)

[Claims] (1) A light control element comprising a structural element having an electric field applying means, and a suspension containing a dispersion medium and a fine polarizing substance dispersed in the dispersion medium, which is housed within the structural element, The polarizing substance is synthesized in the presence of nitrocellulose and is mainly composed of perhalides of organic compounds having aryl groups and saturated branched chains connected to the aryl groups, and contains impurities that reduce electrical resistance and excess nitrocellulose. A light control element characterized in that: and are separated and removed.