JPH01251344A - Optical recording element - Google Patents

Abstract

PURPOSE:To obviate the degradation of definition occurring in flowability with lapse of time by providing a liquid crystal layer contg. a dichromatic dye via a molecular layer of a compd. which is reversibly changed in structure by light on a transparent substrate. CONSTITUTION:This recording element has the structure in which a liquid crystal layer 3 is sandwiched between two sheets of the substrates 1 having the monomolecular layers 2 of a photochromic compd. The photochromic compd. causes a change in the structure when a part A thereof is irradiated by light and, therefore, the perpendicular arrangement of this part is broken and the liquid crystal attains the arrangement in parallel with the surface. The anisotropy of the dichromatic dye changes accordingly. Although the part B which is not irradiated by the light is pale in color, the part A irradiated by the light is changed to a dark color and, therefore, the reading of the light information by the transmittance of the light of the wavelength absorbed by the dye is executed. Since the light of the wavelength which does not generate photochromism by selection of the dye, the breakage of the information is obviated. The degradation of the definition by the liquid crystal having flowability with time is thereby obviated.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a novel optical recording element that utilizes the change in orientation of liquid crystal caused by light. More specifically, 9 the present invention causes a change in the orientation of a liquid crystal layer containing a dichroic dye through the action of a compound that undergoes a reversible structural change when exposed to light, and utilizes this to temporarily or permanently transmit information. This relates to an element for recording data.

Conventional techniques are known to store data using Id+, and to store data using the action of light, and the former is mainly used for display purposes.

By the way, LCD displays that use electrical effects to write information lose their information when the power supply stops.
To preserve this permanently, special measures must be taken, and since patterned electrodes are used, the resolution is low and it is unsuitable for use as a high-capacity recording element.

By the way, LCD displays that use electrical effects to write information lose their information when the power supply stops.
To preserve this permanently, special measures must be taken, and since patterned electrodes are used, the resolution is low and it is unsuitable for use as a high-capacity recording element.

On the other hand, methods that use heat such as laser beams to store information using the action of light can be applied to high-density optical recording, but are limited to pit recording.
The scope of its use is inevitably limited. In addition, a type that mixes a metal compound whose structure changes photochemically and changes its phase by the action of light shows excellent resolution during the initial input of information, but because the liquid crystal flows, Resolution tends to decrease significantly over time. for example.

Photochromic cholesteric liquid crystals obtained by dissolving chiral azobenzene in nematic liquid crystals change to an isotropic phase under the action of ultraviolet light, and this can be used to record information, but over the course of an hour, the liquid crystals deteriorate. It flows and the recorded image becomes unclear. (Refer to the proceedings of the 52nd Spring Annual Meeting of the Chemical Society of Japan, 1986).

Problems to be Solved by the Invention The present invention records information using changes in the orientation of liquid crystals caused by light, and moreover uses polychromatic light that does not cause a decrease in resolution over time due to its fluidity. This was made for the purpose of providing a recording element.

The present 'tM4 was developed as a result of intensive research to develop an optical recording element that utilizes the alignment change of liquid crystals caused by light. First, a molecular layer of a compound that causes a reversible structural change by light is formed on a substrate. If a liquid crystal layer is provided on top of the molecular layer, the liquid crystals will be reversibly aligned in parallel or in series depending on the structure of the two types of compounds that change reversibly with light. Based on this knowledge, he discovered that even if the molecules overlap more than 10,000 times, the information is transmitted quickly, and therefore, unless the light conditions change, the liquid crystal layer does not change and information is retained for a long period of time. As a result, the present invention was completed.

That is, one aspect of the present invention provides an optical recording element in which a liquid crystal layer containing a dichroic dye is provided on a transparent substrate via a molecular layer of a compound that undergoes a reversible structural change when exposed to light.

The transparent substrate in the present invention is a sheet of ordinary silica glass, hard glass, quartz, various plastics, etc., or silicon oxide on the surface thereof.

Tin oxide, indium oxide, aluminum oxide.

Those coated with metal oxides such as titanium oxide, chromium oxide, zinc oxide, or silicon nitride or silicon carbide are used.

Normally, a liquid crystal is used as a sandwich structure filled between two substrates, but in the present invention, at least one of these two substrates may be a transparent substrate, and the other may be made of copper or iron. It can also be a sheet of metal such as aluminum, platinum, or a sheet coated with these metals. These substrates are usually 0. It is used as a sheet with a smooth surface and a thickness of 1 mm.

In the present invention, it is necessary to provide on the above-mentioned substrate a molecular layer of a compound whose structure undergoes a reversible structural change when exposed to light, and photochromic compounds are most commonly used as this compound.

This photochromic compound is a compound that undergoes structural changes under the action of light and changes its behavior with respect to light, such as color tone, and has so far been a carbon-carbon compound.

Photochemical conversion reaction of unsaturated carbon-nitrogen and nitrogen-nitrogen double bonds, valence photoisomerization reaction, heterogeneity reaction
A wide variety of compounds are known that utilize photophotonic ring-opening reactions, photocyclic ring-closing reactions, phototautomerization reactions, and the like. [For example, see Photochromism J (1971), published by Wiley Interscience, edited by G. H. Brown]
. Among such compounds, examples of photochromic compounds based on photogeometric isomerization include azobenzene, selenoindigo, acylindigo, thioindigo, selenoindigo, perinaphthoindigo, hemiindigo, hemitioindigo, and azomethine. An example of a photochromic compound based on a ring-closing reaction is indolinospilobenzopyran.

Indolinospironaphthoxazine, penzothiazolinosviropenzobilane, indolinospirobenzothiopyran, spiroindolizine, etc. are examples of photochromic compounds based on photocyclization reactions, as well as stilbene, fulgide, and photochromic compounds. Examples of photochromic compounds based on sexualization reactions are:

Compounds each having a basic skeleton of salicylideneanyl, 0-hydroxyazobenzene, rhonitosbenzyl, etc. can be mentioned.

In the present invention, in order to provide a molecular layer of such a photochromic compound on a substrate, a method commonly used for vertical alignment of liquid crystals 9, for example, a method of treating the substrate with a photochromic compound having a surface active group, or at least A method of treating with a photochromic compound having a silyl group substituted with one halogen atom or an alkoxy group, a method of treating the substrate surface with a silylating agent having an amino group, and then bonding a photochromic compound having a carboxyl group. [Jay, Gochner (J, C.
ognard), [Molecular Crystals]
and Liquid Crystals (Molecular
Crystals and Liquid Crys
tals) J, Supplement) 1 (1982) and Matsumoto Otsu-1 by Ichiyoshi Tsunoda [Latest Technology of Liquid Crystals J,
(1983)].

Examples of the surface-active groups of the photochromic compound having the above-mentioned surface-active groups include carboxylic acid residues, malonic acid residues, alkyl aluminum salt residues, alkyl salt residues, melee-oxylatochromium complex residues, and esters. residues, nitrile residues, urea residues, amine residues, alcohol residues, phenol residues, betaine residues, and the like. To apply such a photochromic compound having a surface active group to the surface of a substrate, it may be applied directly to the surface of the substrate, or it may be dissolved in a liquid crystal substance. In the latter case, the amount of photochromic compound with 0 surface-active groups added is in the range of 0.01 to 5.0 per weight of liquid crystal.

Examples of the photochromic compounds having a silyl group substituted with at least one halogen atom or an alkoxy group include triethoxysilyl azobenzene, monochlorojethoxysilyl azobenzene, trichlorosilylazobenzene, triethoxysilyl indigo, triethoxysilyl indigo, and triethoxysilyl indigo. Examples include linospirobenzopyran. Treatment with these compounds can be carried out by applying them to the substrate surface as a solution with a concentration in the range of O, 1-10%, preferably 0.5-5%, or by immersing the substrate in this solution. It is done by doing. In this case, the solvent and lumamide are suitable. In addition, the processing time is 1
A suitable time is 30 seconds to 10 minutes. In this method, the substrate surface is treated with a silylating agent.

Furthermore, the bonding strength can be improved.

Next, when the substrate surface is treated with a silylating agent having an amine group and then treated with a photochromic compound having a carboxyl group, examples of the silylating agent used include aminopropyltriethoxysilane, aminopropyljethoxysilane, Examples include aminobutylmethyljethoxysilane and aminobutyltriethoxysilane. Treatment with these silylating agents can be carried out by forming a solution with a concentration in the range of 0.1 to 10%, preferably 0.5 to 5%, and applying this solution to the substrate surface or immersing it in this solution. It is done by doing. The solvents used in this case are water, ethanol, acetic acid, toluene, and acetone.

Jimete 717. 'Hlumamide and the like are preferred, and the treatment time is usually in the range of several micrometers to several tens of minutes.

The amino group of is reacted with a photochromic compound having a carboxyl group according to a conventional method to form an amide bond. In this way, photochromic compounds can be chemically bonded onto the substrate surface.

bond onto the substrate surface. A compound that undergoes a reversible structural change when exposed to light can sufficiently exhibit its function by forming a monomolecular layer, but it can also be formed into two or more molecular layers if desired.

Next, as the liquid crystal for the liquid crystal layer provided on the molecular layer of the compound that undergoes a reversible structural change when exposed to light, any liquid crystal material is selected from among the conventionally known nematic, smectic, and cholesteric liquid crystal materials. However, in the case of smectic liquid crystal materials, it is necessary to select one that takes a nematic liquid crystal phase at a certain temperature. It goes without saying that liquid crystal substances include not only low molecular weight substances but also high molecular weight substances.

Such liquid crystal materials include 1, for example, Engineering Pekin (^.

Bequin) et al., “Molecular Crystals”
and Liquid Crystals (Molecular
crystals and 1quid Crys
tals) J, Volume 115, Page 1. Polymer liquid crystal materials.

For example, 1 Advances in Polymer Science (Advances in Polymer 5cie)
nce), Volume 60/61 (1984). These liquid crystal substances may be used alone or
Moreover, two or more types may be mixed and used.

As a dichroic pigment, for example, Naotake Matsuzawa, "Dyeing Industry"
, Vol. 32, p. 215 (198) is used.

In this case, if you use a temperature-dependent liquid crystal material, for example, a liquid crystal material that does not change its structure when irradiated with light at room temperature, but undergoes a structural change when heated above a certain temperature, it is possible to develop dichroism. A permanent record can be obtained based on the shade of the pigment.

do.

FIG. 1 is a cross-sectional view showing the basic structure of the present invention. A molecular layer 2 of a compound that undergoes a reversible structural change when exposed to light is fixed on a transparent substrate 1, and a layer 2 of a compound that undergoes a reversible structural change when exposed to light is fixed on top of the transparent substrate 1. is further covered with a substrate.

This substrate may be transparent or opaque, its surface may be coated with a molecular layer of a compound that undergoes a reversible structural change when exposed to light, or the liquid crystal may be placed parallel to the surface. It is also possible to use a material coated with a homogeneous orientation that has an alignment effect.

FIG. 2 shows a cross-sectional view of an example of a preferred embodiment of the present invention between two substrates 10) having a monolayer 2 of a photochromic compound on their surfaces.

It has a sandwich structure with a liquid crystal layer sandwiched in between.

In this figure, ■ indicates the state before light irradiation and ■ indicates the state after light irradiation. 111"L -,,,- (I), which are regularly arranged (homeotropically) in a direction perpendicular to The vertical alignment is destroyed and the liquid crystal assumes an alignment parallel to the surface (parallel or homogeneous), resulting in a change in the anisotropy of the dichroic dye.After the structure of the photochromic compound has been changed in this way by light, the single molecule of the photochromic compound In the layer, long sleeves of liquid crystals are aligned parallel to the surface.

The fact that dichroic dyes are also arranged in parallel in accordance with this was discovered for the first time by the present inventors.

Therefore, the part (2) that is not irradiated with light is a light color, but the part (2) that is irradiated with light changes to a dark color.

Optical information can be read based on the transmittance of light at wavelengths that the dye absorbs. Depending on the choice of dye.

Since light of a wavelength that does not cause photochromism can be used to read information, the information will not be destroyed.

Next, FIG. 3 is an example in which an embodiment as-aligned 1114', f)<+ is provided, which is different from the case of FIG. It can be provided by rubbing with this phocohol, polyimide resin, polyoxyethylene, etc., or by vapor-depositing an oxide such as Sin from an oblique direction. In this example, on the photochromic compound monomolecular layer side, the liquid crystals are aligned in a direction perpendicular to the substrate surface, as shown in Figure 3I, but on the homogeneous alignment layer side, they are aligned in a direction parallel to the substrate. It has a structure. and,
When this is irradiated with light, the liquid crystals in the irradiated part (2) are aligned parallel to the photochromic compound monolayer plane, so the whole becomes a homogeneous alignment state, and in the same way as above, the liquid crystals are aligned parallel to the photochromic compound monolayer plane, and in the same way as above, the liquid crystals are aligned parallel to the plane of the photochromic compound monolayer. The optical information can be read out.

In the optical recording element of the present invention, if it is desired to erase the information once recorded, it can be done by irradiating it with light having a different wavelength from the light used during recording to restore the structure of the photochromic compound.

Effects of the Invention The optical recording element of the present invention has the advantage of not exhibiting the disadvantages of information recording using conventional photochromic materials, such as the disadvantage that once recorded information gradually disappears due to repeated reading, and also Since the alignment of the liquid crystals is controlled by a photochromic monolayer, the resolution of fluid liquid crystals is far superior to that of conventional liquid crystals in which photochromic compounds are added.

Furthermore, the optical recording element of the present invention can be suitably used not only for reversible optical information storage but also for optically addressed display.

Example Next, the present invention will be explained in more detail with reference to Examples.

Examples 1-5 4-hexyl-4°-hydroxyazobenzene (1)
1 g (3,73
+/ 1 no 4 no 1 no f〒=11-1(3,69X 10
Add ``ilq'jJ and dimethinogecetamide 5d,
Heated at 100°C for 37 hours. After the reaction was completed, water was added and the mixture was allowed to cool to room temperature, and the precipitated yellow crystals were collected by filtration. This was extracted with ethyl acetate, dried over magnesium sulfate,
The solvent was distilled off under reduced pressure.

The residue was recrystallized from a mixture of hexane and benzene to obtain 1 g of 6-(4-(4-hexylphenylazo)-phenoxy)-hexanoic acid. 200m of this carboxylic acid
g (5,05xlO-'mol>) in 5ml of thionyl chloride
In addition, excess thionyl chloride was distilled off under heating under reflux for 2 hours, and 0.15 g of dry ether 3- and triethylamine was added.
(1,485 x 10-' mol) is added. Add 0.0% triethoxyaminopropylsilane to the mixture under cooling.
11 g (4,98 x 10-' mol) of dry ether solution 3- was added dropwise, stirred for 2 hours, filtered under nitrogen atmosphere to remove salts, and the solvent was distilled off at room temperature under 2a pressure. Yellow waxy N-(3-)ethoxysilylpropyl)-6-(4-(4-hexylphenylazo)
213 mg of phenoxy)hexanoic acid amide was obtained.

f ”fa 1m meji...Ma self + 'l', ';l shi
, -su ■6 謔zu 18b parable ↑ blade ~ ・2wt%
10 pieces of clear quartz plate (IX3cnf) in ethanol solution
It was soaked for 1 minute, air dried, and then dried at 100° C. for 10 minutes.

This was ultrasonically cleaned in methylene chloride for 5 minutes and heated to 100°C.
and dried for 10 minutes. Both sides of this quartz plate are modified with azobenzene, and its absorption light intensity at 340 nm is 0.
010, and was actually colorless and transparent. Using two quartz plates treated in this way, a cyclohexanecarboxylic acid phenyl ester mixed liquid crystal (K -17-N -73-1) was sandwiched and sealed with epoxy resin to create a sandwich cell.

When this was irradiated with 365 nm ultraviolet rays, the blue color of the dye became stronger as azobenzene photoisomerized from trans to cis. Further, when visible light of about 440 nm was irradiated, the color returned to the original pale blue color. This color tone change is reversible in response to alternating irradiation with ultraviolet and visible light.
N & 111% 444W! T--No9 ノ'' W Bar W l Small # -Un Ritz-Knee = 7 There was no disturbance even if I did it. The absorbance at the large absorption wavelength (6231 m) of the dye before and after UV irradiation was 0.17 and 0.55, respectively. Similarly, Table 1 shows the changes in absorbance when the amount of dye dissolved in the liquid crystal was changed.

Table 1 Example of absorbance change of liquid crystal cell containing dichroic dye
Dye concentration Absorbance at 623 nm (wt%) Before UV irradiation After UV irradiation 1 1 0, 1?
0.552 2 0.20
0.443 3 0.31
0.694 4 0J8 0.
825 5 0.60 1.05
Example 6 Two quartz plates coated with azobenzene in the same manner as in Example 1 were used to construct an 8 μm sandwich cell of a mixed liquid crystal containing 5% by weight of dye ① instead of dichroic dye ②. When this cell was alternately irradiated with ultraviolet rays and visible light,
A reversible change in red shade was observed.

H9C40COCH=ct+ -@-N=N -@-N
=N -P-N Example 7 A silylating agent was produced in the same manner using 4-methyl-4'-hydroxyazobenzene instead of 4-hexyl-4'-hydroxyazobenzene in Example 1, and a glass plate was prepared. processed. When a cell in which a mixed liquid crystal containing 2% by weight of dye (2) was sandwiched between the glass plates was alternately irradiated with ultraviolet rays and visible light, a reversible change in blue shade was observed.

Example 8 A silylating agent was produced in the same manner as in Example 1 using 4-cyclohexyl 4'-hydroxyzobenzene instead of 4-hexyl-4'-hydroxyazobenzene,
Treated glass plate. 2% by weight of dye ■ with this glass plate
When a cell sandwiching the mixed liquid crystal containing the liquid crystal was alternately irradiated with ultraviolet rays and visible light, a reversible change in the shade of red was observed.

Figure 1 Figure 2 (B) (A) (B) Figure 3 (D (fI), Procedural amendment (method) % formula % 1, Indication of the case 1988 Patent Application No. 077785 2, Invention Name Optical Recording Device 3, Relationship with the case of the person making the amendment Patent applicant 1-3-1 Kasumigaseki, Chiyoda-ku, Tokyo (+14) Director of the Agency of Industrial Science and Technology Kozo Iizuka 5, Designated Agent 5, Procedural Amendment Order Date - Showa 63
June 8, 1988 (all date of transmission: June 28, 1988) 6. Number of inventions increased by amendment 0 7. Subject of amendment 8. Contents of amendment (1) First from the bottom of page 20 of the specification Add the following items and explanations after line 1.

[

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing one example of the structure of the optical recording element of the present invention, FIG. 2 is a cross-sectional view showing another example and the alignment state of the liquid crystal before and after light irradiation, and FIG. 3 is still another example. FIG. 3 is a cross-sectional view showing the arrangement state of liquid crystals before and after the light irradiation.

Claims (1)

[Claims] 1. An optical recording element in which a liquid crystal layer containing a dichroic dye is provided on a transparent substrate via a molecular layer of a compound that undergoes a reversible structural change when exposed to light.