JPH03105314A - Liquid crystal optical element and production thereof - Google Patents

Abstract

PURPOSE:To provide the optical element consisting of a uniformly oriented high-polymer liquid crystal compd. and the process for producing this compd. by converting a polymerizable group-contg. low-polymer liquid crystal developed on a water surface to a high polymer. CONSTITUTION:The polymerizable group-contg. low-polymer liquid crystal is exemplified by the polymerizable group-contg. low-polymer liquid crystal having a hydrophilic group. The polymerizable group-contg. low-polymer liquid crystal is converted to the high polymer by developing the soln. thereof on the water surface. Various solvents which are compatible with the polymerizable group-contg. low-polymer liquid crystal and have low solubility in water are usable as the solvent to be used for the soln. The method for developing the soln. of the polymerizable group-contg. low-polymer liquid crystal on the water surface is exemplified by a method for dropping the soln. onto the water surface. The soln. spreads immediately on the water surface and a thin film is formed when the soln. is dropped onto the water surface. The thin film developed on the water surface is polymerized by active energy rays to the high polymer, by which the liquid crystalline thin film is formed. The high orientation of this film at need is possible.

Description

[Detailed description of the invention] [Industrial application fields] The present invention relates to a liquid crystal optical element and a manufacturing method.

[Prior Art] In recent years, in contrast to low-molecular liquid crystal compounds that are widely used in the electronics application field, active development has been carried out to apply high-molecular liquid crystal compounds to recording and display elements.

[Problems to be Solved by the Invention] However, since no method has been found for uniformly aligning a polymer liquid crystal compound, it is difficult to obtain a monodomain alignment film like a low molecular liquid crystal compound.

Means for Solving the Problems The present inventors have conducted extensive research on optical elements and manufacturing methods made of uniformly oriented polymeric liquid crystal compounds, and have arrived at the present invention.

That is, the present invention provides a liquid crystal optical element characterized in that it is formed by polymerizing a polymerizable group-containing low-molecular wave crystal developed on a water surface;
and a method for manufacturing an optical element, which is characterized in that a low-molecular liquid crystal containing a polymerizable group is spread on a water surface and a liquid crystalline thin film is formed using active energy rays.

In the present invention, the polymerizable group-containing low-molecular liquid crystal includes a polymerizable group-containing low-molecular liquid crystal having a hydrophilic group. This hydrophilic group includes -COOH, -OH, -NHe. -S
H. -SOsH, -OSOsH, -S04H, -OSO
aH--CONHs, -COCHs. COOCH*,-
NHCONHa. -NHCOCHa, 10 0 O C
Examples include a group selected from the group consisting of R = C Hz.

Polymerizable group-containing low-molecular liquid crystals that have hydrophilic groups can be used as side-chain polymer liquid crystal compounds. A polymer compound contained pendantly inside.
If necessary, a flexible group (hereinafter referred to as substrate) may be included between the main chain and the mesogenic group.

As a mesogenic group, (G). -R, (G)
h-(X)-(Ω). Examples include those expressed as 1R. Here a is 2 or 3 + t) + c is l
Or 2.

R and Teha, Ω, N H C O C H3, C
N, O CH31 NO2. CI, B
r+ NMe2 (Me is methyl 2IO, C IlH
21141 (n is an integer from l to 8), F.
Examples include CF'3.

Also, as X, CH"CH.CH2CH2.CH=C
H-Coo, OCOCH=CH. Co-0, OCO, C
ONH. Examples include NHCO, CH=N, N=CO 2 and the like.

In addition to those mentioned above, examples of the mesogenic group include those containing a cholesteryl group or a chiral nematic group.

Examples of the substrate include methylene chains of 01 to Cap, oxyethylene chains, oxypropylene birene chains, dimethylsiloxane chains, and the like.

The main chain used in the side chain type polymer liquid crystal compound is C
Examples include -C bond and polyene bond.

An example of the former is Macromolecular Hemi-17
Examples include those shown by the following chemical structure described in Vol. 9, p. 254l (1978).

Further, in the present invention, the side chain type polymeric liquid crystal compound may be a ferroelectric liquid crystal, and examples of such a compound include those of the following formula.

C-CH*CH-co
(3) 1 CO yoI May be present or absent. ) As the hydrophilic group Z, -COOH. -OH. -NH2. -SH. -SOxH.
O S OsH, -S O4H, -O S OaH
, -C O NH2, -COCHs. -COOCH
*. -NHCONHe. -NHCOCH HAOC
Mention may be made of groups selected from the group consisting of O C H = C H 2.

Specific examples of the polymerizable group-containing low-molecular liquid crystal include the following.

In the present invention, acrylates and methacrylates having preferred structures are represented by the following formulas.

ah is a cholesteryl group (in the formula, E is H or a methyl group, 1 is an integer of 2 to 4, 2 is a hydrophilic group, and Q is a difunctional group, CIl
s (CH2)I + CIIC-C-6- ((H
a) @ CO2 oN = NG CONIl Nitrogen In the present invention, the side chain type polymeric liquid crystal compound containing a hydrophilic group obtained as a result of polymerizing a polymerizable group-containing low molecular liquid crystal is:
A structure in which a hydrophilic group is bonded to the end of a mesogenic group and/or the end of a non-mesogenic side chain group is preferred.

As a structure in which a hydrophilic group is bonded to the end of a mesogenic group,
(G), -Z1 (Q). Examples include those represented by -(X)-(Q) and -Z.

Here, d is 2 or 3, and es f is l or 2.

Z is a hydrophilic group selected from the above group.

There are various structures in which a hydrophilic group is bonded to the terminal of a non-mesogenic side chain group, for example, (CH*)a-0--COO
H. (CH.)s-0- -Coo-CH2CH
For example, a − O C O − C H = C H 2.

In a side chain polymeric liquid crystal compound containing a hydrophilic group, the molar ratio of mesogenic groups to non-mesogenic side chain groups is usually 1.
00:0 to 20:801 preferably 100:
0 to 50: 5Q. If the mesogenic group content is less than 20%, liquid crystallinity will be poor.

In a side chain polymeric liquid crystal compound containing a hydrophilic group, a mesogenic group and/or a non-mesogenic side chain group containing a hydrophilic group,
The molar percentage of mesogenic groups and/or non-mesogenic groups that do not contain hydrophilic groups is usually from 0.1:99.9 to 50:50. The preferred ratio is 1:99 to 1
0:90. If the content of hydrophilic groups is smaller than this, the desired orientation cannot be obtained. If it is larger, the polymeric liquid crystal compound becomes water-soluble, causing problems in the subsequent alignment step.

The polymerizable group-containing low-molecular liquid crystal may contain a plurality of crosslinkable polymerizable groups in one molecule.

Examples of the group that causes a photopolymerization reaction include a radical polymerization group, a photodimerization group, an azide group, and a cationic polymerization 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 polymeric liquid crystal compounds containing such radically polymerizable groups include acrylic acid ester of hydroxybrobyl cellulose described in Molecular ●Crystals &Liquid●Crystals; Examples include polysiloxanes containing acrylic groups as described in No. 62-29411i57.

Examples of groups that cause other photocrosslinking reactions and groups that cause crosslinking by other reactions include
Examples include those described in the specification of No. 4657.

Preferred crosslinkable groups are photocrosslinkable groups,
Particularly preferred are acrylate and methacrylate groups.

Various ml components and auxiliary agents as described below can be added in advance to the polymerizable group-containing low-molecular liquid crystal, as necessary, as long as they do not interfere with liquid crystallinity.

An example of this is a polymeric liquid crystal compound that does not have a hydrophilic group.

The polymer liquid crystal compound having no hydrophilic group is not particularly limited as long as the polymerizable group-containing low molecular liquid crystal is compatible with the polymer liquid crystal compound containing a polymerized hydrophilic group.

Moreover, a non-liquid crystalline polymer compound can be mentioned as a component that can be added to the polymerizable group-containing low-molecular liquid crystal.

Specifically, in addition to vinyl resins such as vinyl chloride resin, acrylic resin, methacrylic resin, and styrene resin, and copolymers such as vinyl chloride-acrylic copolymer, polyester resin, polycarbonate resin, polyurethane resin, etc. can be mentioned.

The non-liquid crystalline polymer compound may contain a crosslinkable group like the polymerizable group-containing low molecular weight liquid crystal.

Examples of the crosslinkable group include the same groups as those described for the polymerizable group-containing low-molecular 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 crystalline polymer compound containing such a crosslinkable group, various polymer compounds that are practically used as photocurable resins can be used.

Specific examples include triacrylate of triol obtained by addition polymerizing many moles of propylene oxide to glycerin.

As the non-liquid crystalline polymer compound, a film-forming compound is usually used.

Examples of photoinitiators for photocrosslinking include compounds described on page 12 of ``Photo-radiation curing technology'' (Taiseisha, 1985), such as acetophenone, penzophenone, Michler's ketone, benzyl, benzoin, benzoin ether, penzyl ether, benzinoledimethylketanore,
Mention may be made of thioxanthone and their derivatives.

The polymerizable group-containing low-molecular liquid crystal may contain a dichroic dye if necessary for displaying or reading out liquid crystal records. Examples of dichroic dyes include anthraquinone dyes and azo dyes.

The polymerizable, low-molecular-weight liquid crystal can contain a light-absorbing dye, which can be selected depending on the wavelength of the recording light.

When using a semiconductor laser, it is preferable to use a near-infrared absorbing dye (and when using a lle-Ne laser, Ar laser, tungsten lamp, halogen lamp, etc., it is preferable to use a visible light absorbing dye.

Various near-infrared absorbing dyes have been developed in recent years.
Examples include those described in Organic Synthetic Chemistry, Vol. 43, No. 4, pp. 36-45 (1985), such as phthalocyanines, tetradehydrocholine, bezenedithionorennickenol complex, and naphthoquinones.

Furthermore, the polymerizable group-containing low-molecular liquid crystal can contain a non-liquid crystal liquid in order to shorten the response time or lower the driving threshold voltage. Examples of such compounds include 2-oxazolidinones, propylene carbonate, dialkylbisphenols, and alkylcyclohexylcyclohexanes.

In the present invention, the polymerizable group-containing low-molecular liquid crystal is polymerized by spreading its solution on the water surface.

As the solvent used for the solution of the polymerizable group-containing low-molecular liquid crystal, various solvents can be used as long as they are compatible with the polymerizable group-containing low-molecular liquid crystal and have low solubility in water. . Examples of such compounds include aromatic hydrocarbons, halogenated hydrocarbons, ketones, esters, ethers, and the like.

Additives such as alcohols, phenols, or surfactants can also be added to these solvents in order to improve the spreadability of the water surface film.

A method for spreading a solution of a polymerizable group-containing low-molecular liquid crystal on the water surface includes a method of dropping the solution onto the water surface.

When the solution is dropped, it immediately spreads on the water surface to form a thin film.

When developing a solution of a polymerizable group-containing low-molecular liquid crystal, it is desirable to maintain the temperature of the solution of a polymerizable group-containing low-molecular liquid crystal and the temperature of water within a certain range in advance.

The temperature of the solution is usually 20-50°C. temperature is 20℃
If it is lower, the viscosity increases and it spreads uniformly, whereas if it is higher than n<, so°C, the solvent tends to evaporate and wrinkles easily when spread on the water surface. On the other hand, the temperature of the water is preferably 5 to 30
℃, particularly preferably 10 to 25℃.

If the temperature is lower than 5°C, the viscosity of the solution increases and
At temperatures higher than ℃, the solvent evaporates easily.

The thickness of the film formed by casting and drying on the water surface is usually
It is 0.01 to 5 μm. By using a film-forming liquid crystal with a large molecular weight at a low concentration, an extremely thin film of about 0.1 μm can be easily created. Also, relatively thick films can be made using highly concentrated solutions.

Depending on the purpose of the application, several to hundreds of water surface-deployable membranes can be stacked together. By doing so, a uniform and relatively thick film having a thickness of about 0.1 to 10 μm can be obtained.

The polymerizable group-containing low-molecular liquid crystal is spread on the water surface and polymerized by active energy rays to form a liquid crystalline thin film.

The water surface film thus obtained can be further highly oriented if necessary. As a method for highly oriented (A
) stretching orientation, (B) electric field orientation, (C) @field orientation, (D)
(E) Holding on a substrate subjected to chemical alignment treatment or (E) Holding on a substrate subjected to physical alignment treatment.

As the stretching method, a uniaxial stretching method, a biaxial stretching method, an inflation 37 method, etc., which are used for ordinary polymer compounds, can be used.

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

The stretching ratio is usually 50 to 500%, preferably ioo
~300%. Stretching speed is usually 10~■000%
/minute.

In the present invention, the water surface film can also be field oriented. The electric field orientation can be performed, for example, by sandwiching the water surface film between electrodes and applying an electric field. The pair of electrodes is usually provided sandwiching the water surface film, but may take other forms.

In addition to metals such as aluminum and silver, transparent conductors such as indium tin oxide are preferably used as electrode materials.

The electric field usually has a strength of 1 to IOMV/m1 and a frequency of 100
An alternating current of ~10,000 Hz is used.

When an electric field is applied, liquid crystals in the water surface film with positive dielectric anisotropy align perpendicularly to the electrodes, and those with negative dielectric anisotropy align in parallel.

High orientation can be achieved by applying an electric field in the liquid crystal temperature range and slowly cooling to room temperature.

In the present invention, orientation may be performed using a magnetic field.

The strength of the magnetic field in this case is usually 5N20kG, and either a fixed direction magnetic field or an alternating magnetic field may be used.

High orientation can be achieved by applying a magnetic field within the liquid crystal temperature range and slowly cooling to room temperature.

In the present invention, the water surface film may be held and oriented on a substrate that has been subjected to orientation treatment.

In the present invention, chemical alignment treatment is an operation to form a thin alignment layer on the surface of a substrate.
Orientation is controlled by der Waalska, dipole-dipole interactions, and hydrogen bond forces.

Chemical alignment treatment methods include (I) application of alignment agent solution (formation of alignment layer by chemical bonding or adsorption), (2) deployment of alignment agent on water surface (Langmuir Blodgett method) (3)
It can be broadly classified into plasma polymerization.

In the present invention, the monotonous orientation treatment is an operation for deforming the minute shape of the substrate surface.

Physical alignment treatment methods can be broadly classified into (!) rubbing method and (2) vapor deposition method.

Depending on the alignment agent, the alignment method, or the properties of the liquid crystal, the liquid crystal molecules are aligned parallel to, perpendicular to, or oblique to the substrate.

As for specific alignment agents and alignment treatment methods, those described in "Latest Technology of Liquid Crystals", page 53 (Kogyo Chosenkai, published in 1983) can be mentioned.

High orientation can be achieved by maintaining the liquid crystal temperature range for a certain period of time and then slowly cooling it to room temperature.

In the present invention, a desired pattern may be formed by interposing a photomask between the light source and the light source during light irradiation.

In such cases, development, washing, and
dry. In this way, a liquid crystal film having a desired shape can be formed at a desired position on the substrate.

In the present invention, intermediate phases taken by the polymerized liquid crystal include a smectic phase (such as smectic A phase and chiral smectic C phase), a nematic phase, and a cholesteric phase. Smectic C phase is preferred.

In the present invention, the temperature at which the polymerized 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 50°C or higher.

High orientation can be achieved by maintaining the liquid crystal temperature range for a certain period of time and then slowly cooling it to room temperature.

A thin film developed on a water surface and optionally stretched is not self-supporting on its own, so a substrate is usually required. The substrate is selected in consideration of thermal conductivity, mechanical strength, optical properties, flatness accuracy, etc., depending on the purpose of use. Supports include glass, ceramics, plastics, (
Commonly used substrates include acrylic resin, methacrylic resin, polycarbonate resin, polyolefin resin), and metal (aluminum, etc.).

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

When laminating on a substrate, an adhesive, a blue tinting agent, or the like may be used to improve the adhesion between the polymerized liquid crystal and the substrate. As such, it is possible to use pressure-sensitive adhesives and adhesives commonly used for laminated films.

In the present invention, JJI can be crosslinked if necessary. Preferably, crosslinking is carried out using light.

Although ultraviolet rays are usually used as this light, radiation such as electron beams and alpha rays may also be irradiated.

Although both highly oriented and crosslinking can be performed, either one of them may be used.

In addition to the recording/displaying layer made of the liquid crystal film formed on the substrate in this way, layers having various functions for the purpose of recording/displaying can be provided. Examples of such a layer include a light absorbing layer, a reflective layer, an antireflection layer, and a protective layer.

The light-absorbing layer may be formed by coating the above-mentioned light-absorbing dye or by vacuum deposition of carbon or metal (such as bismuth or tellurium). The reflective layer is usually provided by vacuum-depositing aluminum, silver, or the like.

The anti-reflection emperor is Thin Film Handbook, page 820 (Showa 58
A transparent inorganic compound such as magnesium fluoride, such as magnesium fluoride, can be installed by vapor deposition.

The device can be recorded using light. As the recording light, recording light such as a semiconductor laser, an Ar laser, a He-He laser, etc. is used.

As a laser beam irradiation method, generally 0.7 to 1Oμmφ
One example is a method of irradiating a focused beam with a pulse width of 0.1 to 10 μs and an energy of 5 to 2 hll.

The recording light for this element can also be a normal light source, such as a tungsten lamp, a xenon lamp, a high-pressure mercury lamp, or a high-pressure mercury lamp.
It is also possible to use light sources from light emitting diodes. When using such a light source, a pattern can be placed and written between the light source and the 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.

Reading is generally performed using an optical head.

Further, the liquid crystal recording display element of the present invention can be used as a large-area display device, and in this case, illumination by a backlight can be provided from the rear side if necessary.

Erasing can be done by heat or light. If it is caused by heat, use an infrared lamp, nichrome wire heater, etc.
usually! Heat the recording layer to 00-150°C. In the case of erasing with light, the same laser light used for recording can be used.

Recording and erasing can be repeated, for example, 10 to 100 times or more.

[Examples] Hereinafter, the present invention will be further explained with reference to Examples, but the present invention is not limited thereto.

Example I Macromolecules 18 1677 (
Cholesterol, 11-
The following polymerizable group-containing low-molecular liquid crystal (KS3.2 S54.
8 Ch G4.41) was synthesized.

A mixture of 0.5% of the photoinitiator Irgacure 184 (manufactured by Ciba Geigy) was spread on the water surface in the same manner as in Example 1.
Co., Ltd.) using ultraviolet rays (1.OJ/cta)
) was irradiated. The polymer liquid crystal compound film thus obtained was a uniformly oriented film throughout.

This water surface-extended On film was transferred to a glass substrate with a vanadium oxide capped cyanine film, and exposed to semiconductor laser light (830
When irradiated with light (nm), a spot with a diameter of approximately iμ could be recorded.

Example 2 The water surface film of the polymer liquid crystal obtained in Example 1 was sandwiched between two TO glass plates and heated at 1 kHz, 20 V while maintaining the temperature at 80°C.
A voltage of 100 mL was applied and held for 10 minutes, and then slowly cooled to room temperature. It was confirmed that the orientation of this film was further advanced.

In advance, dichroic dye IJD-109 (λmax=7E
When a similarly highly oriented sandwich cell is irradiated with a semiconductor laser and a polymer liquid crystal water surface film containing a 5% blend of iOnm (manufactured by Nippon Kayaku) is irradiated with a semiconductor laser, it becomes approximately 1μ in diameter.
I was able to write the spot of the connoisseur.

[Effects of the Invention] The liquid crystal recording display element of the present invention, which is formed by polymerizing the low-molecular liquid crystal containing a polymerizable group that is developed on the water surface, has hydrophilic groups on the water surface side and hydrophobic main chains on the air surface side. Since the polymer liquid crystal layer is preferentially oriented toward the side, the polymer liquid crystal layer is oriented extremely uniformly, and the contrast of recording and display is high (1.), which is of very high practical value.

Since the recording/display element of the present invention achieves the above effects, it is specifically useful for optical memory displays, electronic blackboards, liquid crystal televisions, etc., and is also useful for nonlinear optical elements, liquid crystal shutters, sunglasses, light control panels, filters, etc. Useful.

Claims (1)

[Scope of Claims] 1. A liquid crystal optical element characterized in that it is formed by polymerizing a low-molecular liquid crystal containing a polymerizable group spread on a water surface. 2. The device according to claim 1, wherein the low molecular liquid crystal has hydrophilicity. 3. The thin film obtained by polymerizing the polymerizable group-containing low-molecular liquid crystal compound spread on the water surface is held or physically aligned on a substrate that has been subjected to stretching orientation, electric field orientation, magnetic field orientation, or chemical orientation treatment as necessary. The element according to claim 1 or 2, which is highly oriented by any one of the methods of holding on a substrate. 4. A method for producing an optical element, which comprises spreading a polymerizable group-containing low-molecular liquid crystal on a water surface and forming a liquid crystalline thin film using active energy rays. 5. The production according to claim 4, wherein the thin film is highly oriented by any one of the following methods: stretching orientation, electric field orientation, magnetic field orientation, holding on a chemically oriented substrate, or holding on a physically oriented substrate, if necessary. Law.