JPH01134425A - Recording display element and method for using said element - Google Patents

Abstract

PURPOSE:To enable erasing in a short period of time by crosslinking a film formable liquid crystal and heating a recording display element to the transparent point of the film formable liquid crystal or above then rapidly cooling the same to execute recording by forming a light scattering state, and by executing erasing at need. CONSTITUTION:The film formable liquid crystal is crosslinked and a high-polymer liquid crystal and/or nonliquid crystalline high-polymer compd. is crosslinked. The temp. at which the film formable liquid crystal is transformed from a liquid crystal phase to an isotropic liquid, i.e., the transparent point is usually >=0 deg.C and is more preferably >=50 deg.C. Recording with the recording display element is executed by heating the element to the transparent point or above, then rapidly cooling the same to form the light scattering state. Erasing is executed by maintaining the element for the specified period of time or above at the temp. between the glass transition point and transparent point of the film formable liquid crystal. The liquid crystal structure is formed in the crosslinked high polymer and the film formable liquid crystal is crosslinked in such a manner; therefore, the rapid erasing is attained when the element is maintained for the specified period of time or above at the temp. between the transparent point and the glass transition point.

Description

[Detailed description of the invention] [Industrial application field] FIELD OF THE INVENTION The present invention relates to recording and display elements and methods of use.

[Prior Art] In recent years, the development of applications for recording and display devices using polymer liquid crystals such as polyacrylate-based liquid crystals has become active, and it has become possible to write and erase data using lasers (for example, the Japan Society of Applied Physics 1987
Spring 2015 29O-8) Writing is written into a transparent amorphous glass state by irradiating a light-scattering polymer liquid crystal with a laser and rapidly cooling it from above the clearing point. Erasing is constant at a temperature slightly lower than the clearing point. When held (annealed) for a period of time or longer, the liquid crystal phase is regenerated and returns to the state before writing.

[Problems to be Solved by the Invention] However, there is a problem that erasing takes too much time.

[Means for Solving the Problems] The present inventors have arrived at the present invention as a result of extensive studies on elements that can perform erasing in a short time and methods of use.

That is, the present invention provides a recording/display element comprising a film-forming liquid crystal containing a liquid crystal compound and optionally a non-liquid crystal polymer compound, wherein the film-forming liquid crystal is crosslinked (the first invention). ) and a liquid crystal compound and, if necessary, a non-liquid crystal polymer compound, and a crosslinked film-forming liquid crystal that is heated to a temperature above the clearing point of the film-forming liquid crystal and then rapidly cooled to form a light scattering state. record,
This is a method of using a recording/displaying element (second invention) characterized in that erasing is performed if necessary.

In the present invention, liquid crystal compounds include high molecular liquid crystal compounds (abbreviated as polymer liquid crystal) and low molecular liquid crystal compounds (abbreviated as low molecular liquid crystal).

Film-forming liquid crystals include (1) polymeric liquid crystals, (2) mixtures of polymeric liquid crystals and low-molecular liquid crystals, (3) mixtures of polymeric liquid crystals and non-liquid crystalline polymer compounds, (4) low-molecular liquid crystals, and Examples include mixtures of non-liquid crystal polymer compounds and (5) mixtures of polymer liquid crystals, low molecular liquid crystals, and non-liquid crystal polymer compounds.

In the present invention, the film-forming liquid crystal is crosslinked, and the polymer liquid crystal and/or the non-liquid crystal polymer compound is crosslinked.

Polymer liquid crystals include main chain type polymer liquid crystal, side chain type polymer liquid crystal,
It is also possible to use any of the main chain-side chain composite polymer liquid crystals (polymer liquid crystals containing mesogens in the main chain and side chains).

The main chain polymer liquid crystal is a polymer compound in which a mesogen is contained in the main chain, and may contain a flexible group (hereinafter referred to as a "spacer") if necessary.

Examples of mesogens include those represented as 0-X-〇. Here, as X, CH=CH, C-C
, CH=CH-Co, Co-0, Co-NH, CH=N
, N=N, N=N, 0, ↓ -0-, etc.

Examples of the spacer include C1 to C12 methylene chains, oxyethylene chains, oxypropylene chains, dimethylsiloxane chains, and the like.

Examples of main chain type polymeric liquid crystals include those having the following structure described in Macromolecule Hemi, Vol. 184, p. 253 (1983).

[n CH2+T10-O-CO-0-0-CO-0-
0-0+ (1) Polypeptides such as poly(γ-benzyl glutamate) and cellulose derivatives such as hydroxypropyl cellulose can also be used as other main chain polymer liquid crystals.

A side chain type polymer liquid crystal is one in which a mesogen is included in the side chain, and a spacer may be interposed between the main chain and the mesogen. In addition to those mentioned above, mesogens include those containing a cholesteryl group or a chiral nematic group. Examples of the main chain used in side-chain polymer liquid crystals include C--C bonds and 5i-0 bonds. Examples of the former include Macromonoculare Hemi-Volume 179;
Examples include those represented by the following chemical structure described on page 2541 (1978).

→CH2-CH-)-C0o-fCH2+gO-00-OCH3 (2) Examples of the latter include those represented by the following chemical structure described in JP-A-56-79173.

'0-COO-0-OCH3'0-CO0-CholC
hol = Cholesteryl group Examples of main chain-side chain composite polymer liquid crystals include Macromonoculare Hemi; Rapid Communication;
Examples include those described in Vol. 7, p. 389 (1986). Specifically, a polymer compound having a unit represented by the formula can be mentioned.

Examples include ferroelectric polymer liquid crystals, specifically compounds having a structural unit represented by the following formula (5) that takes a chiral smectic C phase.

In the present invention, when the polymer liquid crystal is crosslinked, the crosslinkable groups include groups that cause a reaction triggered by light irradiation, that is, groups that cause a photocrosslinking reaction, and other groups (that cause crosslinking by reactions other than photocrosslinking). It can be broadly divided into

Examples of the group that causes a photocrosslinking reaction include a radical polymerizable group, a photodimerizable group, an azide group, and a cationic polymerizable group.

Examples of the radically polymerizable group include an acrylate group, an α-chloroacrylate group, a methacrylate group, a styryl group, a vinyl group, a vinyl ester group, a vinyl ketone group, and an acrylamide group.

Examples of polymer liquid crystals containing such radically polymerizable groups include Molecular Crystals and Liquids.
Crystals 1984 Volume 102 (Letters) 25
Examples include the acrylic acid ester of hydroxypropylcellulose described on page 5 and those having a structural unit represented by the following general formula (6).

R (where m and n are integers of 2 to 20, p and q are 0.1.2
, R is H or CH3, and X is CH=
, CH, C-C, CH=CH-Co, C0-01CO-
NH, CH=N, N=N, N=N, etc. ↓ Y is CN, OCH3, QC4H9, Cl! ,F,CH
3, C4H9, CF3, etc. ) Photodimerizable groups include cinnamate group, cinnamoyl group, cinnamylidene acetate group, cinnamylidene acetyl group, α-cyanocinnamylidene acetate group, α-cyanocinnamylidene acetyl group, p-phenylene diacrylate group. and 2-furyl acrylate group.

Examples of polymeric liquid crystals containing such groups include those having a structural unit represented by the following general formula (7).

[In the formula, m, n, p, q, R, X, and Y are the same as in general formula (6). ] As an example of a polymer liquid crystal containing an azide group, the following general formula (
Examples include those having the structural unit shown in 8).

[In the formula, m, n, p, q, X, and Y are the same as in general formula (6). ] Examples of the cationically polymerizable group include an epoxy group, a vinyl ether group, an N-vinylcarbazole group, a coumaron group, and an indene group.

Groups that are crosslinked by reactions other than photocrosslinking include isocyanate groups (crosslinking with polyamine compounds), epoxy groups (crosslinking with polyamine compounds and polyfunctional acid anhydrides),
Amino group (crosslinked by polyisocyanate compound, polyepoxy compound, polyfunctional acid halide compound, polyfunctional acid anhydride), hydroxyl group (crosslinked by polyisocyanate compound), trialkoxysilyl group (crosslinked by water), carboxyl group (crosslinking with metal ions).

Among the crosslinkable groups, preferred are photocrosslinkable groups. Particularly preferred are polymeric liquid crystals containing photodimerizable groups represented by formulas (7) and (8) and polymeric liquid crystals containing azide groups.

Examples of low-molecular liquid crystals include biphenyl and its esters, phenylcyclohexane and its esters, phenylcyclohexane and its esters, cyclohexylcyclohexane and its esters, phenyldioxane and its esters, and phenylpyrimidine. In addition, low-molecular liquid crystals containing chiral alkyl groups,
Specifically, those described in Chapter 7 of "Liquid Crystal Basics" co-edited by Mitsuharu Okano and Ashibu Kobayashi (Baifukan, published in 1985), such as benzoic acid phenyl esters, benzylideneanilines, and biphenylcarboxylic acid esters. can be used. Tolans containing a chiral alkyl group (for example, those described in Japanese Patent Application No. 43696/1982) can also be used.

Examples of non-liquid crystalline polymer compounds include olefin resins, acrylic resins, methacrylic resins, polyethylene resins, polyester resins, polyurethane resins, polycarbonate resins, styrene-butadiene copolymers, and vinylidene chloride-acrylonitrile copolymers. Examples include merging.

When the non-liquid crystal polymer compound contains a crosslinkable group, examples of the crosslinkable group include the same groups as those described for the polymer liquid crystal, and preferred ones are also the same.

The crosslinkable group may be included in either the main chain or the side chain of the non-liquid crystalline polymer compound.

As the non-liquid crystal polymer compound containing such a crosslinkable group, various polymer compounds that are practically used as photocurable resins can be used. A specific example is triacrylate of a triol obtained by addition polymerizing many moles of propylene oxide to glycerin.

A film-forming non-liquid crystal polymer compound is usually used as the non-liquid crystal polymer compound, but a non-liquid crystal polymer compound that is non-film forming may also be used.

In the present invention, examples of the intermediate phase taken by the film-forming liquid crystal include smectic phase (smectic A, chiral smectic C phase, etc.), nematic phase, cholesteric phase, etc. If a short response time is required, chiral smectic C phase is preferred.

In the present invention, the temperature at which the film-forming liquid crystal transitions from a liquid crystal phase to an isotropic liquid, that is, the clearing point, is usually 0°C or higher, but
Preferably it is 50°C or higher.

The average molecular weight (abbreviated as MC) per crosslinking point of the film-forming liquid crystal is usually 200 to 100.0OO1, preferably 300 to
It is 30.000.

Various auxiliary agents can be added to the film-forming liquid crystal in advance, if necessary.

A photoinitiator can be added to the film-forming liquid crystal as an auxiliary agent for causing photocrosslinking.

Examples of photoinitiators that cause photocrosslinking of substances containing radical polymerizable groups, photodimerizable groups, and azide groups include compounds described in "Light/Radiation Curing Technology" (Taiseisha, 1985), p. 12, such as acetophenone and benzophenone. , Michler's ketone, benzyl, benzoin, benzoin ether, benzyl dimethyl ketal, thioxanthone and derivatives thereof.

As a photoinitiator when using photocationic polymerization, JP-A-60-71628 and JP-A-56-163 are used.
121, such as diphenyliodonium hexafluoroarsenide, diphenyliodonium hexafluoroline, triphenylsulfonium hexafluoroline, and triphenylsulfonium hexafluoroline.

The film-forming liquid crystal can contain a polymerization inhibitor in order to prevent crosslinking during processing, processing, or storage of a polymeric liquid crystal containing a crosslinkable radical polymerizable group. As such a polymerization inhibitor, Japanese Patent Publication No. 57-284
98, for example, 2,6-sheet tert
- Phenols such as butylhydroxytoluene; Catechols such as catechol and p-tert-butylcatechol; Hydroquinones such as hydroquinone and hydroquinone monomethyl ether; Benzoquinone, 2.5
- Quinones such as diphenyl-p-benzoquinone; di-
Examples include amines such as p-fluorophenylamine and phenothiazine; known polymerization inhibitors such as copper powder.

For film-forming liquid crystals, if necessary, reactive diluents are used to control the viscosity during stretching, change the performance of the final cured product, such as the glass transition point, and change the curing speed. can be contained. Examples of reactive diluents include those described in Japanese Patent Publication No. 57-28498, such as acrylates [ethylene glycol di(
meth)acrylate, propylene glycol di(meth)
Polyfunctional (meth)acrylates such as acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, pentaerythritol tri(meth)acrylate, and oligoester (meth)acrylates thereof: Methyl(meth)acrylate , alkyl acrylates such as ethyl (meth)acrylate], allyl conductors [diallyl phthalate, etc.], unsaturated nitriles [(meth)acrylonitrile, etc.], vinyl aromatic hydrocarbons (styrene, divinylbenzene, etc.), vinyl esters ( vinyl acetate, vinyl propionate, etc.).

Since it is necessary to display or read out a record of the liquid crystal, the film-forming liquid crystal may contain a dichroic dye. Examples of dichroic pigments include merocyanine pigments, anthraquinone pigments, azo pigments, styryl pigments, azomethine pigments, tetrazine pigments, methine pigments, and squalirium pigments. can.

The film-forming liquid crystal can contain a light-absorbing dye, and as a dye that absorbs at the wavelength of the recording light, it is preferable to use a near-infrared absorbing dye when using a semiconductor laser.
When using an e-Ne laser, an Ar laser, a tungsten lamp, a halogen lamp, etc., it is preferable to use a visible light absorbing dye.

Various near-infrared absorbing dyes have been developed in recent years.
Organic Synthetic Chemistry Vol. 43, No. 4, pp. 36-45 (198
5), such as phthalocyanine dyes, tetradehydrocholine, benzenedithiol nickel complexes,
Examples include naphthoquinone dyes. As a commercially available product,
IR-750 (743), IRQ-002 (980)
, IRQ-003 (980) (manufactured by Nippon Kayaku) Two NK series For example, N-78 (800), 123 (
817), 125 (740), 12B (761), 20
14 (780), 2421 (740), 2772 (7
70) IR absorber PA series (manufactured by Japan Angko Dyes Research Institute), such as P^-1001 (1110)
, 1003 (885) , 1005 (850) , 10
06 (870) (manufactured by Mitsui Toatsu Chemical Co., Ltd.) (in the above, the number in parentheses indicates λmax).

Examples of visible light absorbing dyes include Solvent Yellow 98, Solvent Orange 72, Solvent Yellow 2, and Rhodamine B.

Further, the film-forming liquid crystal can contain a non-liquid crystal liquid or a chiral substance in order to shorten the response time or lower the driving threshold voltage. Examples of the non-liquid crystal liquid include 2-oxazolidinones, propylene carbonate, dialkylbisphenols, and alkylcyclophenylcyclohexanes. Examples of chiral substances include benzoic acid-2-methylbutyl ester.

In the present invention, an example of the formulation of the film-forming liquid crystal is as follows. 0% is % by weight.

Liquid crystal compound 30-100% 50-9
5% (polymer liquid crystal 30~100 50~
95) □(Low molecular liquid crystal 0~70
0-40) Non-liquid crystalline polymer compound O-70
0 to 70 (when using polymer liquid crystal O to 50 0
~30) (When using low molecular liquid crystal O~70 4
0-70) Photoinitiator O-io
o~5 Polymerization inhibitor O~50~0.1
Reactive diluent O-30 0-10 Dichroic dye O-10 0-5 Light absorption dye
O~20 1~10 Non-liquid crystal liquid
O~20 0~10 chiral substance
Among the O~200~10 liquid crystal compounds, the amount of polymeric liquid crystal is usually 0~100%, preferably 50~100% based on the total weight of polymeric liquid crystal and low molecular weight liquid crystal.

In the present invention, the film-forming liquid crystal is stretched in a non-quality solid state,
It is processed by orientation. The non-quality solid state can be obtained by rapidly cooling the film-forming liquid crystal from above its clearing point. Specifically, this can be done by heating liquid crystal to a temperature above its clearing point using a conventional method to make it an isotropic liquid, and then rapidly cooling it to below its glass transition point by immersing it in a refrigerant or the like.

As such a refrigerant, water, liquid nitrogen, dry ice-methanol, etc. are usually used. Further, instead of using a refrigerant, it is also possible to rapidly cool the material by bringing it into close contact with a low-temperature metal plate, for example, by passing it through a low-temperature roll.

The cooling rate is usually 10° C./second or more. Alternatively, the time from the temperature above the clearing point to the glass transition point is usually within 10 seconds.

It is possible to determine whether the product is defective or not by examining the birefringence using a polarizing microscope.

In the processing method of the present invention, stretching is usually performed at a temperature below the clearing point of the film-forming liquid crystal. At temperatures higher than the clearing point, it is difficult to orient the film even if it is stretched.

In the present invention, the clearing point of the film-forming liquid crystal is usually 50'C or higher.

As the stretching method, a uniaxial stretching method, a biaxial stretching method, an inflation method, etc., which are performed with ordinary polymer compounds, are possible.

When stretching, it is possible to add a solvent (for example, toluene, chlorobenzene) or to stretch in an atmosphere containing solvent vapor.

The stretching ratio is usually 50 to iooo%, preferably 10
It is 0-800%.

The stretching speed is usually 10 to 1000%/min.

The film thickness after stretching is usually 0.1 to 100 μm, preferably 0.5 to 20 μm.

When the film thickness is less than 1 μm, self-supporting properties are lost and handling becomes difficult, but even in such a case, lamination and stretching can be applied.

This is a method in which a thick film before stretching is placed on a rubber support plate or support frame, stretched, and then transferred to another substrate, and is described in Applied Physics, Vol. 49, p. 159 (1980). With this method, stretched films as thin as 0.05 μm can be produced.

A film subjected to such stretching is oriented in a certain direction, and its birefringence is usually in the range of 0.01 to 0.1.

If the stretched and oriented film contains a photocrosslinkable group, it will be photocrosslinked and fixed. Photo-crosslinking and fixing are performed by transferring the alignment film to the substrate.

The substrate is preferably selected in consideration of thermal conductivity, flatness accuracy, mechanical strength, hygroscopicity, warpage, lightness, workability, cost, etc. Substrates include glass, ceramics, and plastics (acrylic resin, methacrylic resin, polyester resin, polycarbonate resin, epoxy resin, etc.)
, metal, and other commonly used recording material substrates.

Among these, glass is preferable from the viewpoint of flatness accuracy. Furthermore, plastics are preferable from the viewpoint of lightness, workability, cost, etc.

The shape of the base body can be varied depending on the purpose, and examples thereof include a plate shape, a disk shape, a drum shape, and the like.

In order to improve the adhesion between the film-forming liquid crystal and the substrate when it is transferred to the substrate, an adhesive, an adhesive, or the like may be used.

As such, it is possible to use pressure-sensitive adhesives and adhesives such as those used in laminated films.

In the present invention, photocrosslinking and solidification are performed by light irradiation. This light includes ultraviolet light.

Examples of the ultraviolet source include low-pressure, medium-pressure, high-pressure or ultra-high-pressure mercury lamps, ultraviolet fluorescent lamps, etc. The wavelength of the light used for photocrosslinking of the film-forming liquid crystal in the present invention is usually 2.
It is an arbitrary wavelength of 00 to 500 nm, and is sufficiently cured at this wavelength.

Furthermore, in the present invention, crosslinking can be achieved by irradiating radiation such as electron beams or α-rays without performing light irradiation.

If the temperature of the film-forming liquid crystal rises above the clearing point due to light irradiation, radiation irradiation, etc., the orientation will be lost, so the irradiation is performed below the clearing point. For this purpose, the film-forming liquid crystal may be irradiated while being cooled.

Additionally, a filter or the like that blocks heat rays may be used.

In addition to the recording/display layer consisting of the liquid crystal film thus formed on the substrate, layers of various functional films can be provided for the purpose of recording/displaying. Examples of such a layer include a light absorption layer, a reflection layer, an antireflection layer, and a protective layer.

The light-absorbing layer may be formed by coating the above-mentioned light-absorbing dyes, or may be formed by vacuum deposition of carbon or metal (bismuth, tellurium, etc.).

The reflective layer is usually provided by vacuum-depositing aluminum, silver, or the like.

The anti-reflection layer is described in the Thin Film Handbook, page 820 (1982,
A transparent inorganic compound, such as magnesium fluoride, described by Ohm Co., Ltd., can be installed by means such as vapor deposition.

The protective layer can use transparent inorganic compounds such as silicon oxide and aluminum nitride as well as transparent plastics.

The thickness of the recording layer, light absorption layer, reflection layer and protective layer is usually 0.05 to 10 μm, 0.05 to 1 μm and 0.1 μm, respectively.
~100 μm. For anti-reflection layer, usually 0,01
~1 μm, but the greatest effect is obtained when the film thickness is chosen according to the formula (where λ is the wavelength of light used for recording, reading, and erasing, n is the refractive index, and m is 0 or a natural number). can get.

The recording/display element of the present invention records by heating above the clearing point and then rapidly cooling to form a light scattering state.

This element can record using light, and laser light such as a semiconductor laser, an argon laser, or a helium-neon laser is used as the recording light.

As for the laser beam irradiation method, -ffi is 0.7 to 2μ.
An example is a method of irradiating a beam focused to mφ with a pulse width of 0.1 to 10 μsec and an energy of 5 to 20111 W.

As recording light for this element it is also possible to use other recording light from conventional light sources, such as tungsten lamps, xenon lamps, high-pressure mercury lamps and light-emitting diodes.

When using other recording lights, a pattern can be placed and written between the light source and the optical element. Furthermore, an arrayed device such as a liquid crystal printer or a light emitting diode printer can also be used.

Furthermore, instead of light, a heat source such as a thermal printer head can be used for recording.

In high-density optical recording, reading is generally performed using an optical head.

Erasing is performed by maintaining the temperature between the glass transition point (Tg) and the clearing point of the film-forming liquid crystal for a certain period of time or more.

Erasing can be done by heat or light.

As a method of erasing by heat, there is a method of heating with an infrared lamp, a nichrome wire heater, etc., usually at a temperature of 100 to 150° C. for several tens of seconds.

In the method of erasing with light, the light includes laser light such as a semiconductor laser that can be used for the above-mentioned recording. Separate lasers (eg, a semiconductor laser and an argon laser) can also be used for recording and erasing.

An example of a method for erasing with a laser beam is to narrow down the focus to usually 2 to 10 μm and irradiate the laser for a time of about 1 to 50 μsec.

Recording and erasing is a pain in the ass. For example 10 times or 100
more than once).

[Examples] The present invention will be further described below with reference to Examples, but the present invention is not limited thereto.

Example 1 4-aryloxybenzoic acid-4°-cyanophenyl ester [compound (1)] was synthesized as follows. First, 4-
138g oxybenzoic acid and 132g potassium hydroxide
was dissolved in 270 ml of water, 6 g of tetrabutylammonium bromide was added thereto, and then a toluene diluted solution of allyl chloride ioo was added dropwise with stirring at 40°C. After completion of the reaction, the pH of the aqueous layer was adjusted to 3 with 4N hydrochloric acid, and the solid after washing with water was recrystallized with ethanol to give allyloxybenzoic acid (89%).
Og was obtained (yield 49%).

Next, allyloxybenzoic acid 36.4. thionyl chloride 3
Add 5 ml of 4-cyanophenol and stir until the reaction mixture becomes clear, remove excess thionyl chloride, and add 4-cyanophenol 2
3.8. , toluene 50ml, dimethylformamide 1
ml was added, washed with water, toluene was removed, and recrystallized from ethanol to obtain 34.6. Compound (1) was obtained (yield 62%). Compound (1) did not have a liquid crystal phase and had a melting point of 10
The temperature was 4°C.

Next, 8.37 g of compound (1) and polymethylhydrosiloxane (polymerization degree 240, R X-6 manufactured by Shin-Etsu Chemical Co., Ltd.
499J) 1.566g of tetrahydrofuran 2
The solution was dissolved in 5ml, 3cm of platinum silver chloride was added, and the mixture was stirred at 45°C for 5 hours. This product was reprecipitated three times with methanol and dried to obtain 8.2 g of solid. When this product was observed under a polarizing microscope, it was confirmed that it was a polymeric liquid crystal exhibiting liquid crystallinity at temperatures below 120°C. Differential thermal scanning calorimetry (
According to DSC>, the glass transition point was 18° C. [This material will be referred to as polymer liquid crystal (1)].

Next, SANNIX Polyol GP-300 [an average of 3.6 moles of propylene oxide added to glycerin. Sanyo Chemical Industries, Ltd.] 300 g, isophorone diisocyanate 625 g, cyclohexanone 300 g and dibutyltin dilaurate 50 g were charged into a colben and reacted at 75 to 85°C for 4 hours, followed by 348 g of 2-hydroxyethyl acrylate and hydroquinone monomethyl. 0.1 g of ether was charged, and the reaction was further carried out for 200 hours to obtain an oligomer solution (1) having three acryloyl groups in one molecule.

Polymer liquid crystal (1) 7.0g, oligomer solution (1) 3
．． 7g, IRQ-003 (manufactured by Nippon Kayaku ■) 0.3. After homogeneously mixing 0.5 g of benzoin methyl ether and removing the solvent, the solid obtained was a film-forming liquid crystal with a clearing point of 86°C. This was heated to 95°C and poured into methanol at -70°C to obtain an amorphous solid. A film obtained by stretching this by 150% at 20° C. was placed on a glass plate and crosslinked by irradiation with ultraviolet rays.

Next, a semiconductor laser (830 nm) was irradiated with a focused beam of about 2 μmφ at an output of 15 mW, heated to above the clearing point, and rapidly cooled, the area changed to an opaque state and recording was performed. Further, when the same part was irradiated for 5 μsec with an output of 15 mW and a beam diameter of approximately 4 μmφ, the beam was maintained between the glass transition point and the clearing point for a certain period of time, and erasing was performed. Same record/
It was confirmed that the erasing operation could be repeated 10 times.

Example 2 8.37 g of compound (1) synthesized in Example 1 and 1.9 g of polymethylhydrosiloxane rX-6499J
14. was dissolved in 25 ml of tetrahydrofuran, 3 ml of chloroplatinic acid was added, and the mixture was stirred at 45°C for 5 hours. Next, 0.5 g of allyl methacrylate (manufactured by Aldrich) and 10 μm of hydroquinone monomethyl ether were added, and the mixture was further stirred for 5 hours. This product was reprecipitated three times with methanol and dried to obtain 8.9 g of solid.

When this product was observed under a polarizing microscope, it was confirmed that it was a polymeric liquid crystal exhibiting liquid crystallinity at temperatures below 105°C. D
According to SC, the glass transition point was 7° C. (this material is referred to as polymer liquid crystal (2)).

Add benzoin methyl ether to 10 g of polymer liquid crystal (2)
,s,, IRQ-0030,3, are mixed uniformly, 11
Heating to 0°C and pouring into -70°C methanol gave an amorphous solid. This was stretched 200% at 20°C, and the resulting film was crosslinked in the same manner as in Example 1.

Recording/erasing was performed in the same manner as in Example 1, and recording/erasing was 10
I confirmed that it can be done twice.

[Effects of the Invention] The recording/display element of the present invention has a liquid crystal structure formed in a crosslinked polymer, and has the following effects.

1. The time required for erasing can be shortened. Since the film-forming liquid crystal is cross-linked, it is quickly erased when kept at a temperature between the clearing point and the glass transition point for a certain period of time or more.

2. The device of the present invention has excellent durability. Since the rewritable optical recording media currently in use are made of metal, they are inherently susceptible to oxidation. There are problems with long-term durability.

3. The manufacturing process up to crosslinking can be carried out using the same processing methods as for ordinary plastic films, and because of its good processability, it is suitable for large-area applications.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view showing an example of the recording/display element of the present invention. 1. Anti-reflection layer 2, transparent substrate 3, liquid crystal layer 4, light absorption layer diagram Mentan 1 diagram

Claims (1)

[Scope of Claims] 1. A recording/display element comprising a film-forming liquid crystal containing a liquid crystal compound and, if necessary, a non-liquid crystal polymer compound, wherein the film-forming liquid crystal is crosslinked. 2. A recording display element made of a crosslinked film-forming liquid crystal containing a liquid crystal compound and, if necessary, a non-liquid crystal polymer compound, is heated to a temperature above the clearing point of the film-forming liquid crystal and then rapidly cooled to form a light scattering state. A method of using a recording/display element characterized by recording and, if necessary, erasing. 3. The method according to claim 2, wherein erasing is carried out by holding the film-forming liquid crystal at a temperature between the glass transition point and the clearing point for a certain period of time or more. 4. Claims 2 or 3 in which the film-forming liquid crystal is composed of a polymer liquid crystal compound or this and a non-liquid crystal polymer compound
Usage as described in section. 5. The method according to any one of claims 2 to 4, wherein the film-forming liquid crystal comprises a low-molecular liquid crystal, a polymer liquid crystal compound, and/or a non-liquid crystal polymer compound. 6. The method according to any one of claims 2 to 5, wherein the film-forming liquid crystal has an average molecular weight per crosslinking point of 300 to 30,000. 7. The method of use according to any one of claims 2 to 6, wherein the film-forming liquid crystal has a clearing point of 50°C or higher.