JPH07311394A - Production of liquid crystal optical element - Google Patents

Abstract

PURPOSE:To make a retardation value smaller, to lessen coloration and uneven colors and to obtain excellent bistability, dimensional stability to deformation and orientation stability by producing a liquid crystal optical element using a ferroelectric liquid crystal material compsn. consisting of a ferroelectric liquid crystal material and crosslinkable resin. CONSTITUTION:The films of a mixture composed of the ferroelectric liquid crystal material and the crosslinkable resin are formed on the electrodes of a substrate with electrodes. A substrate with electrodes is then laminated thereon and after the liquid crystal material is subjected to uniaxial orientation at need, a crosslinking treatment is executed. The ferroelectric liquid crystal material to be used in such a case is not particularly restricted, insofar as the material is a low-molecular or high molecular ferroelectric liquid crystal exhibiting a chiral smectic C phase (SmC*). Such liquid crystal materials include ferroelectric low-molecular liquid crystal, ferroelectric highmolecular liquid crystal or mixtures composed thereof. The use of these liquid crystal materials by further mixing other resins, such as a liquid crystalline polymer, olefin resin, acrylic resin, polymethacrylic resin and polystyrene resin polyester resin therewith is possible as well.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a liquid crystal optical element using a ferroelectric liquid crystal substance composition.

[0002]

2. Description of the Related Art In recent years, a liquid crystal optical element in which a ferroelectric liquid crystal is used as a liquid crystal material, the orientation of the liquid crystal is highly controlled, and the liquid crystal material is sandwiched between two substrates provided with electrodes. However, it has attracted attention because of its excellent characteristics such as high-speed response to external stimuli such as electric fields and excellent contrast ratio, and has come to be widely used as a liquid crystal display element, a liquid crystal storage element, and the like. It was However, when a liquid crystal optical element is manufactured by using a liquid crystal material consisting of a ferroelectric liquid crystal substance, the cell thickness cannot be increased, and a conduction defect or color unevenness due to birefringence interference occurs, or bistability is generated. Is likely to be non-uniform, and it is difficult to increase the area.

In order to improve this, a method for controlling the light scattering state in a liquid crystal device containing a liquid crystal substance having a smectic phase and a medium encapsulating the same is described in JP-A-62-48789. Has been done. Since the liquid crystal element shown here has an electric field response in the nematic phase, the response speed is slow (several tens to several hundreds of ms), and the smectic phase only retains the state in the nematic phase, and does not scatter or scatter. Since the light is turned on and off depending on the mode, there is a problem that the contrast is low.

Further, a liquid crystal optical element using a composite film containing a ferroelectric liquid crystal substance and a thermoplastic polymer is disclosed in Japanese Patent Laid-Open Publication No.
As described in JP-A-3-25622, it is necessary to use a dry / wet film forming method, a water surface development method or the like in order to prepare a composite film, and a plurality of layers must be laminated to form an electro-optical element. However, there is a problem that productivity is poor, it is difficult to increase the area, and sufficient alignment cannot be obtained by the conventional rubbing method and the alignment treatment is difficult.

Further, a liquid crystal optical element using a liquid crystal material in which a liquid crystal substance is dispersed in a transparent epoxy resin in a capsule shape is described in Japanese Patent Publication No. 61-502128, which also has a nematic phase. There is a problem that the response speed is slow because of the electric field response, and the contrast is low because the light is turned on and off by the scattering non-scattering mode.

[0006]

The present invention is capable of increasing the cell thickness of a liquid crystal optical element as compared with a conventional liquid crystal material, having a high response speed to an electric field, and a high contrast ratio. Using a dielectric liquid crystal substance composition, the retardation value is small even in a thick cell,
An object of the present invention is to provide a manufacturing method capable of manufacturing a liquid crystal optical element which has little coloring or color unevenness, is excellent in bistability, is excellent in dimension against deformation, and is excellent in orientation stability and at low cost.

[0007]

Means for Solving the Problems As a result of intensive studies for solving the above problems, the present inventors have found that a liquid crystal using a ferroelectric liquid crystal substance composition composed of a ferroelectric liquid crystal substance and a crosslinkable resin. The inventors have found that the above object can be achieved by producing an optical element, and completed the present invention.

That is, according to the present invention, a mixture of a ferroelectric liquid crystal substance and a crosslinkable resin is formed into a film on an electrode of a substrate with an electrode, then the substrate with an electrode is laminated, and if necessary, the liquid crystal substance is uniaxially added. The present invention provides a method for producing a liquid crystal optical element, which comprises aligning and then performing a crosslinking treatment.

The ferroelectric liquid crystal substance used in the present invention is not particularly limited as long as it is a low-molecular or high-molecular ferroelectric liquid crystal exhibiting a chiral smectic C phase (SmC ^* ).
Ferroelectric low-molecular liquid crystal, ferroelectric high-molecular liquid crystal, or
There is a mixture of these.

Examples of the ferroelectric low-molecular liquid crystal include, for example, one or more kinds of ferroelectric low-molecular liquid crystals, and a mixture of one or more kinds of ferroelectric low-molecular liquid crystals and other low-molecular liquid crystals. There can be mentioned a ferroelectric low-molecular liquid crystal and the like.

Examples of the ferroelectric polymer liquid crystal include, for example, one or two or more ferroelectric polymer liquid crystals, one or two or more ferroelectric low-molecular liquid crystals, and one or two or more ferroelectric liquid crystals. Ferroelectric polymer liquid crystal composed of polymer liquid crystal,
Examples thereof include ferroelectric polymer liquid crystals composed of one or more kinds of ferroelectric low-molecular liquid crystals and one or more kinds of other polymer liquid crystals.

That is, as the ferroelectric polymer liquid crystal, a ferroelectric polymer liquid crystal (a homopolymer or a copolymer or a mixture thereof) in which polymer molecules themselves exhibit ferroelectric liquid crystal characteristics, a ferroelectric polymer liquid crystal And other polymer liquid crystals and / or normal polymers, ferroelectric polymer liquid crystals and ferroelectric low-molecular liquid crystals, ferroelectric polymer liquid crystals, ferroelectric low-molecular liquid crystals and polymer liquid crystals and/
Alternatively, it is possible to use a polymer liquid crystal exhibiting all ferroelectric properties, such as a mixture with a usual polymer, or a mixture thereof with a usual low-molecular liquid crystal.

Among the above ferroelectric polymer liquid crystals, for example, a side chain type ferroelectric polymer liquid crystal can be preferably used, and a side chain type ferroelectric polymer liquid crystal having a chiral smectic C phase is particularly preferable. It can be used preferably.

Specific examples of the side chain type ferroelectric polymer liquid crystal include, for example, polymers, copolymers or blends thereof having a repeating unit represented by the following general formula. [I] Polyacrylate type (Japanese Patent Application No. 61-305251)
No. and Japanese Patent Application No. 62-106353 filed by the applicant)

[0015]

[Chemical 1] [In the formula, k is an integer from 1 to 30,

[0016]

[Chemical 2] X is -COO- or -OCO-, R ₂ is -COOR ₃ , -O
COR ₃ , -OR ₃ , or -R ₃ , where R ₃ is

[0017]

[Chemical 3] (In the formula, m and n are each independently an integer of 0 to 9, q is 0 or 1, and R ₄ and R ₅ are each -C.
H ₃ , a halogen atom or CN, provided that when R ₅ is —CH ₃ , n is not 0, C ^* represents an asymmetric carbon atom, and C ^(*) is n ≠ 0. Means an asymmetric carbon atom. )
Represents a group represented by. The number average molecular weight of this polymer is preferably 1,000 to 400,000.
If it is less than 1,000, the moldability of the polymer film or coating film may be impaired.
If it exceeds 50,000, unfavorable results such as a long response time may appear. A particularly preferable range of the number average molecular weight depends on the kind of R ₁ , the value of k, the optical purity of R _{3 and} the like, and therefore cannot be unconditionally specified, but is 1,000 to 200,000.

The general method for synthesizing this polymer is as follows:

[0019]

[Chemical 4] (Here, k, R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , m and n are as described above.) It can be obtained by polymerizing by a known method.

Among the polyacrylate compounds, examples of the temperature T _sc ^* showing the SmC ^* phase of the liquid crystal represented by the following formula and the average molecular weight M _n are as follows.

[0021]

[Chemical 5] (A) k = 12, M _n = 5300, T _sc ^* : 5 to 12 ° C. (b) k = 14, M _n = 6500, T _sc ^* : 13 to 31
C [II] polyether type (such as the one filed by the applicant as Japanese Patent Application No. 61-309466)

[0022]

[Chemical 6] (In the formula, k, R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , m, n and X are the same as those in the above [I].) The number average molecular weight of this polymer is preferably 1, 000 to 400,000.
If it is less than 1,000, the moldability as a film or coating film of this polymer may be impaired.
If it exceeds 50,000, unfavorable results such as slow response speed may appear. A particularly preferable range of the number average molecular weight depends on the kind of R ₁ , the value of k, the optical purity of R ₃ , and the like, and therefore cannot be unconditionally specified, but 1,000 to
It is 200,000.

The general synthetic method of this polymer is as follows:

[0024]

[Chemical 7] (Here, k, R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , m, n, and X are the same as those described above.), And can be obtained by polymerizing by a known method. it can.

Among the polyether type, the temperature T _sc ^* and the average molecular weight M _n indicating the SmC ^* phase of the liquid crystal represented by the following formula
An example of is as follows.

[0026]

[Chemical 8] (A) k = 8, M _n = 2800, T _sc ^* 24 to 50 ° C. (b) k = 10, M _n = 2400, T _sc ^* : 19 to 50
C. [III] polysiloxane type (Japanese Patent Application No. 62-11471)
(No. 6 filed by the applicant)

[0027]

[Chemical 9] (In the formula, R ₆ is a lower alkyl group, and k, R ₁ , R ₂ , R ₃ ,
R ₄ , R ₅ , m, n and X are the same as above. ) The number average molecular weight of this polymer is not particularly limited,
It is preferably 0 to 400,000. When the number average molecular weight is less than 1,000, the moldability of the polymer as a film coating film may be impaired, while 4
If it exceeds 0,000, unfavorable results such as slow electric field response speed may appear. A particularly preferable range of the number average molecular weight depends on the type of R ₁ group, the values of k, m and n, the optical purity of the R ₃ group, etc., and therefore cannot be unconditionally specified, but
It is 1,000 to 200,000.

This polymer has, for example, the following formula:

[0029]

[Chemical 10] (In the formula, R ₆ has the same meaning as described above.) And an alkylhydropolysiloxane having a repeating unit represented by the following formula and H ₂ C = CH (CH ₂ ) _k-2 -OR ₁ (wherein R 6 ₁ , R ₂ , R ₃ , R ₄ , R ₅ , k, m, and n have the same meanings as described above.), And can be synthesized by reacting with a liquid crystal unit compound represented by the above condition. .

Among the polysiloxane-based compounds, examples of the temperature T _sc ^* and the average molecular weight M _n showing the liquid crystal SmC ^* phase represented by the following formula are shown below.

[0031]

[Chemical 11] (A) k = 6, M _n = 16400, T _sc ^* : 70 to 90
℃ (b) k = 8, M n = 15000, T sc *: 39~91
° C [IV] polyester system (such as that filed by the applicant as Japanese Patent Application No. 61-206851)

[0032]

[Chemical 12] [In the formula, R ₇ is H, CH ₃ or C ₂ H ₅ , s is an integer of 1 to 20,
A is O (oxygen) or -COO-, t is 0 or 1, R ₁ , R ₂ ,
R ₃ , R ₄ , R ₅ , k, m and n have the same meanings as described above. ), Or

[0033]

[Chemical 13] [In the formula, s, A, t, R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , k, m and n have the same meanings as described above. ) These polymers are
It is obtained by a general polycondensation reaction of polyester. That is, with a dibasic acid of the above structure or these acid chlorides,
It is obtained by a polycondensation reaction of a dihydric alcohol.

The number average molecular weight of these polymers is 100
It is preferably in the range of 0 to 400,000. If the molecular weight is less than 1,000, the moldability of the polymer as a film or a coating film may be impaired, while 4
If it exceeds 0,000, unfavorable results such as slow response speed may appear. A particularly preferable range of the number average molecular weight depends on the kind of R ₂ , the value of k, the optical purity of R ₃ , etc., and therefore cannot be unconditionally specified, but it is usually 1,000 to 20.
It is 10,000. [V] A copolymer containing repeating units of the above [I] polyacrylate type, [II] polyether type, [III] polysiloxane type and [IV] polyester type.

Specific examples containing the repeating units [I] to [IV] are as follows.

A copolymer containing the repeating unit [I] and the following repeating units:

[0037]

[Chemical 14] (Wherein R ₈ is H, CH ₃ , Cl, F 2, Br, or I, and R ₉ is
Alkyl or aryl C ₁ ~ _10. ) The number average molecular weight M _n of this copolymer is 1,000 to 400,000, preferably 1,000 to 200,000.

The repeating unit of [I] is 20 to 9
0% is preferable.

It is a precursor monomer of the repeating unit of [I]

[0040]

[Chemical 15] And a copolymer obtained by polymerizing the following monomers.

[0041]

[Chemical 16] Wherein, R ₁₀ is alkyl or aryl of C ₁ -C _20. ] The repeating unit of [I]

[0042]

[Chemical 17] A copolymer containing a repeating unit of. (In the formula, u is an integer of 1 to 30, and R ₁₁ is

[0043]

[Chemical 18] X ¹ is -COO-, -OCO- or -CH = N-, and R ₁₂ is
-COOR ₁₃ , -OCOR ₁₃ , -OR ₁₃ or -R ₁₃ , and R ₁₃
Is alkyl of C ₁ ~ _10, fluoroalkyl or chloroalkyl. ) The ferroelectric polymer liquid crystal used in the present invention is not limited to those having 1 or 2 asymmetric carbon atoms at the end portion of the side chain in the polymer, but not at the end portion of the side chain. Those containing 3 or more carbons can also be used.

Further, it is also possible to use a mixture of the ferroelectric polymer liquid crystal and a low molecular liquid crystal having SmC ^* .

Further, as a ferroelectric polymer liquid crystal, for example, a blend of a polymer having a proton donor and / or a proton acceptor in each and a ferroelectric low molecular weight compound (Japanese Patent Application No. 61-169288). It can be inferred from what a person applied for).

As this ferroelectric polymer liquid crystal, for example, there is one in which a low-molecular liquid crystal shown below and polyvinyl acetate are hydrogen-bonded to form a polymer.

Examples of the ferroelectric low molecular weight liquid crystal are as follows.

[0048]

[Chemical 19] (Here, z is an integer of 3 to 30.) 4- [4 '-(12-dimethylolpropionyloxidedecyloxy) benzoyloxy] benzoic acid 2-
Methyl butyl ester 4- [4 '-(12- (2,2-diacetoxypropionyloxy) dodecyloxy) benzoyloxy]
Benzoic acid 2-methylbutyl ester 4 '-(12-dimethylolpropionyloxidedecyloxy) biphenyl-4-carboxylic acid 2-methylbutyl ester 4'-[12- (2,2-diacetoxypropionyloxy) dodecyloxy] Biphenyl-4-carboxylic acid 2-methylbutyl ester 4 '-[4 "-(12-dimethylolpropionyloxidedecyloxy) benzoyloxy] biphenyl-4-carboxylic acid 2-methylbutyl ester 4'-[4"-( 12- (2,2-diacetoxypropionyloxy) dodecyloxy) benzoyloxy] biphenyl-4-carboxylic acid 2-methylbutyl ester 4- [4 ″-(12-dimethylolpropionyloxy) dodecyloxybiphenyl-4′- Carbonyloxy] benzoic acid 2-me Cylbutyl ester 4- [4 ″-(12- (2,2-diacetoxypropionyloxy) dodecyloxy) biphenyl-4′-
Carbonyloxy] benzoic acid 2-methylbutyl ester Still another type of ferroelectric polymer liquid crystal is, for example, a blend of a ferroelectric low molecular weight liquid crystal and a thermoplastic amorphous polymer [Japanese Patent Application No. 59-169590]. (JP-A-61-
No. 47427), an application by the present applicant] and the like can be mentioned.

This liquid crystal is composed of a thermoplastic amorphous polymer 10
Liquid crystal composition consisting of ˜80 wt% and low molecular weight liquid crystal 90˜20 wt%, which is obtained by adding a certain amount of a specific amorphous polymer to a low molecular weight liquid crystal which originally has no self-shape retention ability. Can be formed into a film or the like, and the self-shape retention ability is imparted by forming the film or the like.

As the thermoplastic amorphous polymer used in this liquid crystal composition, those having no optical anisotropy such as polystyrene and polycarbonate are used. Also,
Examples of the low-molecular liquid crystal include DOBAMBC (p-decyloxybenzylidene-amino-2-methylbutyl cinnamate) 4'-octyloxybiphenyl-4-carboxylic acid 2
-Methylbutyl ester 4- (4 "-octyloxybiphenyl-4'-carbonyloxy) benzoic acid 2-methylbutyl ester 4-octyloxybenzoic acid 4- (2-methylbutyloxy) phenyl ester 4'-octyloxybiphenyl -4-carboxylic acid 3
-Methyl-2-chloropentyl ester 3-methyl-2-chloropentanoic acid 4 ', 4 "-octyloxybiphenyl ester p-hexyloxybenzylidene-p'-amino-2
A ferroelectric liquid crystal compound having an SmC ^* phase such as -chloropropylcinnamate 4- (2-methylbutylbenzylidene) -4'-octylaniline is used.

In the present invention, the liquid crystal material may further contain another liquid crystal polymer or other liquid crystal polymer within a range not hindering the purpose of the present invention.
Olefin resin, acrylic resin, methacrylic resin, polystyrene resin, polyester resin, polycarbonate resin, styrene-butadiene copolymer,
It is also possible to mix and use a resin such as vinylidene chloride-acrylonitrile copolymer.

As the crosslinkable resin used in the present invention, resins such as epoxy resin, unsaturated polyester resin and crosslinkable silicone resin are preferably used. Here, the crosslinkable resin contains a curing agent such as amine of epoxy resin and acid anhydride, and a curing agent such as styrene of unsaturated polyester resin.

Typical examples of the above-mentioned crosslinkable resins are listed below. Epoxy resin

[0054]

[Chemical 20] Unsaturated polyester resin

[0055]

[Chemical 21] Silicone resin

[0056]

[Chemical formula 22] The weight fraction of the crosslinkable resin in the ferroelectric liquid crystal substance composition is usually 5 to 90%, preferably 10 to 70%. If the amount of the crosslinkable resin is too large, the liquid crystal portion is small and the contrast is lowered. If it is too small, the mechanical stability of the device is lowered because the upper and lower substrates are not sufficiently filled.

The method of mixing the ferroelectric liquid crystal substance and the crosslinkable resin is not particularly limited as long as it is a method of mixing so that the liquid crystal capsules can be present, but the following simple mixing method and solution mixing method can be mentioned. .

The simple mixing method is performed at room temperature or at a temperature at which the viscosity of the liquid crystal becomes small [chiral smectic C phase (SmC ^* ), smectic A phase (SmA), nematic phase (N), isotropic phase (Iso)).
Alternatively, the cross-linkable resin before cross-linking and the ferroelectric liquid crystal substance are kneaded at a temperature such as a mixed phase thereof that is not a crystal phase or a glass phase. As for the degree of kneading, the size of the liquid crystal capsule is several μ
Although it is preferably m or less, it is usually practically sufficient if it is visually uniform.

The solution mixing method is a method in which a ferroelectric liquid crystal substance and a crosslinkable resin before crosslinking are dissolved in a suitable solvent and mixed. As the solvent, methylene chloride, chloroform,
Various materials such as toluene, xylene, tetrahydrofuran, methyl ethyl ketone, dimethylacetamide, dimethylformamide can be used. By evaporating the solvent, a uniformly dispersed mixture can be obtained, and the size of the liquid crystal capsule can be changed by adjusting the evaporation rate.

In the present invention, the ferroelectric liquid crystal substance composition obtained by the above mixing method is formed into a film on a substrate with electrodes,
Next, a substrate with electrodes is laminated, and if necessary, a ferroelectric liquid crystal substance is uniaxially oriented, and a crosslinkable resin is crosslinked to obtain an element.

The device is obtained by laminating a substrate with an electrode and a film of the ferroelectric liquid crystal substance composition, and by coating the substrate with an electrode with the ferroelectric liquid crystal substance composition to form a film on the electrode. There is a method of laminating attached substrates.

The former method is a ferroelectric liquid crystal having a thickness of 1 to 20 .mu.m, preferably 1.5 to 15 .mu.m, using a film forming method which is carried out for a usual polymer such as a casting method, an extrusion method and a pressing method. A liquid crystal optical element is prepared by forming a blend film of a substance composition and sandwiching both sides of the film with transparent electrodes on at least one side. A transparent substrate can be provided on one side or both sides of this element as required.

As a concrete example of the transparent electrode, for example, N
Examples thereof include a tin oxide film called an ESA film, an indium oxide film mixed with tin oxide called an ITO film, an indium oxide film, a vapor-deposited film of gold or titanium, or another thin metal or alloy.

Specific examples of the substrate include, for example, crystalline polymers such as uniaxially or biaxially stretched polyethylene terephthalate, amorphous polymers such as polysulfone and polyethersulfone, polyolefins such as polyethylene and polypropylene, polyamides such as polycarbonate and nylon. Examples thereof include a thermoplastic resin plate and a glass plate.

The ferroelectric liquid crystal substance composition is formed into a slightly thick film (2 to 50 μm) at the time of film formation, and is uniaxially stretched to about 2 to 5 times before being laminated with an electrode. Good. By doing so, the alignment treatment of the ferroelectric liquid crystal substance can also be performed.

The latter method of forming a film by coating is a method of forming a ferroelectric liquid crystal substance composition on an electrode of a substrate with an electrode by a coating method, and laminating an electrode or a counter substrate with an electrode thereon.

According to this method of forming a film by coating, the ferroelectric liquid crystal substance can be directly aligned by a bar coater or the like by appropriately selecting the coating temperature and the coating speed. The application is usually performed by moving the ferroelectric liquid crystal substance composition on the electrode using a coating roller such as a cylindrical roller or a spatula-shaped bar to form a film. The same kind of electrode and kind of substrate as those used in the above method are used. The thickness of the ferroelectric liquid crystal substance composition is usually 0.5 to 10 μm, preferably 0.5 to 4 μm.
It is suitable to set it within the range of about m. Further, a solution of a ferroelectric liquid crystal substance composition of 5 to 50% by weight is applied to a substrate with an electrode by a roll coater, a gravure coater, screen printing, etc., and then the solvent is evaporated, and an electrode or a substrate with an electrode is laminated on this. The method is also preferably used.

Next, the liquid crystal optical element of the present invention must be a birefringent element in order to obtain high contrast in switching by an electric field. For this purpose, the liquid crystal substance is subjected to uniaxial alignment treatment substantially parallel to the cell surface.

There are a method of performing this orientation treatment simultaneously at the time of film formation and a method of performing it after film formation and lamination.

As a method of orienting during film formation, the film obtained by the above film formation is stretched and then laminated. Alignment is obtained by stretching the film 2 to 5 times at the temperature at which the liquid crystal exhibits SmC ^* phase, SmA phase, N phase, N ^* phase or a mixed phase of these and isotropic phase (Iso phase). To be If the orientation is not sufficient, heat to the isotropic phase and bring the liquid crystal temperature to 0.0
Orientation becomes good by cooling at 5 to 20 K / min, preferably 0.05 to 5 K / min. In addition, the film obtained by the above-mentioned coating can be oriented at the same time as the coating, if the coating conditions are appropriately set.

Examples of the method for carrying out the orientation treatment after film formation and lamination include rubbing, oblique vapor deposition, shearing, and orientation by bending.

According to the rubbing method, a film of polyimide (PI), polyvinyl alcohol (PVA) or the like is preliminarily formed on at least one electrode-attached substrate by a spin coating method, a dipping method, a coating method, or the like in an amount of 20 to 10,000 angstroms. It is preferably formed to 2000 angstroms or less, and rubbed in one direction with a cloth or the like, and the liquid crystal is 0.05 to 20 K / min, preferably 0.05 to 5 K / min from the isotropic phase. An oriented liquid crystal layer is obtained by cooling with. (Rubbing method: Masato Isogai, Akio Mukai,
Fumio Nakano, Mikio Sato, Proceedings of 43rd Annual Meeting of the Japan Society of Applied Physics (Autumn 1982) According to the oblique evaporation method, an inorganic substance such as SiO or SiO ₂ is obliquely evaporated on at least one substrate with an electrode. Every
An oriented liquid crystal layer is obtained by cooling from the isotropic phase at the same rate as in the rubbing method. (W.Vrbach, M.Boix, and E.
Guyon; Appl. Phys, Lett., 25 (1974) 479) According to the shearing method, the upper and lower substrates with electrodes are slightly displaced from each other and a shear stress is applied to the liquid crystal to obtain an aligned liquid crystal layer. (NAClark and ST Langerwall; Appl.
Phys, Lett., 36 (1980) 899) According to the alignment method by bending, for example, the liquid crystal layer oriented by bending and deforming while continuously moving the liquid crystal optical element between at least two free-rotating rollers is formed. can get. If this alignment treatment is performed before the crosslinkable resin is sufficiently cured, a large shear is easily applied to the liquid crystal portion, and a higher alignment state can be obtained.

Next, in manufacturing the liquid crystal optical element of the present invention, a crosslinking operation is carried out in order to impart strength and stability during film formation. The cross-linking operation is performed by mixing a cross-linking agent (curing agent) in the cross-linkable resin. Usually, it may be mixed during the preparation of the solution before film formation. In the solution state, since the crosslinking does not easily proceed due to the dilution effect, the viscosity of the solution does not change rapidly. After film formation, crosslinking starts after the solvent is evaporated. Leave at room temperature (several minutes to several 1 depending on the type of resin)
For some time, the crosslinking and curing time can be shortened by heating to an appropriate temperature or irradiating with ultraviolet light. This heating or ultraviolet light irradiation may be performed before or after the lamination. When a film is formed from a mixture of liquid crystal and a crosslinkable resin without using a solvent, crosslinking starts at the time of preparation of the mixture, and therefore a resin having a long crosslinking (curing) time may be selected for stable continuous production.
Of course, the curing after the film formation can be accelerated by heating and irradiation with ultraviolet light.

The liquid crystal optical element of the present invention comprising the ferroelectric liquid crystal substance composition obtained by crosslinking the crosslinkable resin in this manner has excellent film shape stability, but especially when the liquid crystal is used for a long period of time. If there is a risk of leakage, the cell end faces may be sealed and fixed with an epoxy adhesive or the like.

[0075]

EXAMPLES The present invention will now be described in detail based on examples, but the present invention is not limited thereto.

Example 1 The following low molecular weight ferroelectric liquid crystal was used as the ferroelectric liquid crystal substance.

[0077]

[Chemical formula 23] As the cross-linking resin, a commercially available fast-curing epoxy resin (Cemedine High Super, manufactured by Cemedine Co., in which the epoxy resin and the cross-linking (curing) agent were in a 1: 1 weight ratio) was used.

5 g each of the liquid crystal and the resin were dissolved in 90 g of dichloromethane, and a 1: 1 mixed solution (10 wt.
%) Was prepared and applied to a PES substrate with ITO (width 15 cm, thickness 125 μm) using a roll coater at room temperature. The film thickness after evaporation of the solvent was 6 μm. After this same P
It was laminated with an ES substrate and subjected to bending alignment treatment at 50 ° C. to obtain a liquid crystal optical element of 15 cm × 200 cm. When this device was placed under crossed Nicols and a voltage of ± 20 V was applied, a contrast ratio of 45 and a response time of 400 were obtained at 25 ° C.
It became an element of μs. Retardation value is Δn · d =
It was 0.28 (Δn: refractive index anisotropy, d: cell thickness). In addition, the size of the particles (microcapsules) in the liquid crystal part was about 15 to 2 μm under microscopic observation, and bistability was exhibited, so that the state was maintained even when the voltage was turned off.

Furthermore, after the resin was cured, even if bending deformation (up to a radius of curvature of 5 cm) was applied, the alignment state of the liquid crystal was not disturbed, and even if cutting was performed with a cutter or the like, there was no conduction.

The transmitted light when operated in the birefringence mode under crossed Nicols is white with a light yellowish tint, which corresponds to a thickness of about 3 μm in the conventional cell structure in which no resin is mixed.

The measurement of the response time is required for the change in the transmitted light intensity when the sign of the applied electric field is reversed to reach 10% to 90% when the liquid crystal cell is sandwiched between two orthogonal polarizers. This was done by measuring the time.

Example 2 Low molecular ferroelectric liquid crystal DOBAMBC

[0083]

[Chemical formula 24] And epoxy resin (epoxy resin and cross-linking agent 1: 1 weight ratio, Pernox, MG-150) each 10
g, the mixture containing 7 g is dissolved in chloroform,
A wt% solution was made. The above solution is PET with ITO
It was applied onto a substrate (100 μm thick) using a rod coater, and after solvent evaporation, a 5 μm composite film was obtained. A PES substrate with ITO (125 μm) as a counter substrate is a rubber roller,
Laminating using a laminator consisting of a metal roller, 20
The element was cm × 1.5 m. This element was subjected to a bending orientation treatment using a roller as shown in FIG. ₁ (in the figure, T ₁ = 25 ° C., T ₂ = 125 ° C., T ₃ = 85 ° C., T
₄ = 70 ° C., v = 3 m / min, the roll diameter is 80 mm large and 40 mm small), however, the contrast ratio was 57 and the response time was 170 μs at 70 ° C. when ± 10 V was applied. The retardation value Δn · d was 0.23. As a result of measuring the bistability at 70 ° C., the change in the light transmittance after the electric field was turned off under crossed Nicols was about 5% after 24 hours, and sufficient performance was confirmed. In addition, in a bright state after switching, it was a white color with a light yellow color as in Example 1.

As a comparison, an alignment film having a cell thickness of 5 μm was prepared using only liquid crystal (DOBAMBC), and the same measurement was performed. The contrast ratio was 40, and the light transmittance was 25 after 24 hours in the evaluation of bistability. It was changing about%. Further, it was confirmed that the transmitted light was colored in deep red to green in a bright state, and color unevenness was caused by a slight thickness unevenness.

In order to exhibit the same level of performance as in Example 2 only in the liquid crystal part, it is necessary that the contrast is 3 μm or less, the bistability is 3.5 μm or less, and the coloring is 2 μm or less. It was

Example 3 As a ferroelectric polymer liquid crystal, a polyacrylate-based liquid crystal was used.

[0087]

[Chemical 25] As a crosslinkable polymer, MG-150 manufactured by Pernox Co., Ltd. 9
The mixture was kneaded at 0 ° C to obtain a mixture. Weight ratio is 3 (liquid crystal): 2
After kneading for about 10 minutes as a (polymer), a visually almost uniform mixture was obtained.

This mixture was quickly I-coated with a gravure coater.
It was applied to a PES substrate with TO to obtain a film of about 4 μm.
The coating was performed at 105 ° C. Subsequently, the substrates are laminated with the same type of substrate and passed through a roll shown in the drawing of Example 2 (T ₁ = 90 ° C, T ₂ = 90 ° C, T ₃ = 42 ° C, T ₄ = 25 ° C,
V = 3 mm / min), and orientation treatment was performed. The processes up to this point were all carried out continuously to obtain a liquid crystal element web having a width of 15 cm and a length of 30 m. This was allowed to stand for about 20 hours, and a portion of 15 cm × 20 cm was cut out after the polymer was cured, and the contrast ratio was measured. As a result, 88 was obtained by applying ± 10 V at 24 ° C. (under crossed Nicols). The response time was 60 ms when ± 30 V was applied. Retardation value Δ
n · d was 0.25. In addition, the state after switching was maintained at almost 100% even after 48 hours, confirming sufficient bistability. In addition, the color in the bright state was almost white, and there was no uneven color. Furthermore, when about 10 sheets were cut out from the original liquid crystal element at different positions, the contrast ratios were all 80 or more, and good reproducible results were obtained in terms of bistability and colorability.

Example 4 Ferroelectric Polymer Liquid Crystal Polyoxirane System

[0090]

[Chemical formula 26] Bisphenol A type diglycidyl ether as a crosslinked polymer (Epicote 82 manufactured by Yuka Shell Epoxy Co., Ltd.)
8D) and 4,4'-diaminodiphenylmethane (DDM manufactured by Hanai Chemical Co., Ltd.) as a hardening agent, the former vs. the latter 6: 4.
A weight ratio was used. A mixture of the above liquid crystal and polymer in a weight ratio of 1: 1 was dissolved in dichloromethane to give a concentration of 15w.
After making t% solution, 30cm x 50cm IT
Screen printing was performed on a PET substrate with an O electrode (thickness of 125 μm). The film thickness was about 15 μm immediately after printing, but it was about 3.5 μm after solvent evaporation. After that, a PES substrate with ITO (100 μm) was laminated as a counter substrate and subjected to bending alignment treatment. (Same as the diagram of Example 2. T
₁ = T ₂ = 105 ° C, T ₃ = 80 ° C, T ₄ = 60 ° C) The contrast ratio under crossed Nicols is 28 ° C, ± 15V
The application time was 76 and the response time was 30 ms. The retardation value Δn · d was 0.23. In addition, the film has no coloring due to the birefringence effect and can be displayed in black and white with good visibility. It was found that the bistability was 100% after the electric field was removed and after leaving at 28 ° C. for 24 hours, the transmittance was 100%. After curing the crosslinkable polymer, a part of it was cut out and observed under a microscope. As a result, the size of the liquid crystal capsule was 3 μm in diameter.
It was almost all about m.

Example 5 A ferroelectric polymer liquid crystal used in Example 4 and an unsaturated polyester resin (Easter manufactured by Toyo Toatsu Co., Ltd.) were mixed in a ratio of 1: 1 without using a solvent, and 20 cm × 20 cm by a pressing method. ,
It was molded to a thickness of 6 μm. After that, it was laminated with a PES substrate with ITO. After the resin was semi-cured, the same orientation treatment as in Example 4 was performed, and the contrast ratio was 28 ° C., ± 15.
It became 80 when V was applied. The response speed was 75 ms. When the retardation value was measured, Δn · d = 0.26
Met. The microscopic observation revealed that the size of the liquid crystal capsule was 5 μm in average diameter. There was little coloration by visual observation, and the response was uniform. Bistable state after electric field removal is 36 ° C
So, it was maintained at 92% even after being left for one week.

Example 6 Ferroelectric liquid crystal used in Example 1 and crosslinkable silicone resin
1: 3 mixture of fat (TSE3450 manufactured by Toshiba Silicone)
25wt. (Including curing agent) dissolved in dichloromethane
% Solution is applied by a gravure coater, laminated and laminated.
It was The substrate is a PES substrate with ITO (width 30 cm)
I was there. The film thickness between the electrodes was about 7 μm. Orientation treatment is real
In the device shown in Example 2, T₁= 25 ° C, T₂= 60 ℃, T₃=
48 ° C, T _Four= 25 ° C. and V = 1 m / min.

The contrast ratio was 42 at 25 ° C. and ± 4 V applied, and the response time was 900 μs. The retardation value was Δn · d = 0.22. The microscopic observation made it difficult to distinguish the liquid crystal part and the resin part because they were almost evenly dispersed. It was white with no visible coloration. The bistable state after removal of the electric field was maintained at 95% for 1 hour at 36 ° C., which was an excellent result in practical use. This element has a radius of curvature of 5 cm
However, the alignment state and the film thickness were kept extremely stable.

[0094]

The liquid crystal optical element using the ferroelectric liquid crystal substance composition of the present invention is a liquid crystal optical element having a large area and having a high response speed to an electric field and a high contrast ratio. Further, it is also possible to obtain excellent color stability, bistability without color unevenness, and dimensional stability.

In the method for manufacturing a liquid crystal optical element of the present invention, since the cell thickness can be increased, the manufacturing conditions are relaxed, conduction failure is less likely to occur, and the bending alignment method is effective for the alignment of the ferroelectric liquid crystal substance. Since it can be used, liquid crystal optical elements can be easily manufactured with extremely few processes,
It is possible to increase the area of the device and continue production.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a state where an element is oriented.

Claims (3)

[Claims] 1. A liquid crystal optical device characterized in that a mixture of a ferroelectric liquid crystal substance and a crosslinkable resin is formed into a film on an electrode of a substrate with an electrode, then the substrate with an electrode is laminated, and a crosslinking treatment is carried out. Device manufacturing method. 2. A mixture of a ferroelectric liquid crystal substance and a crosslinkable resin is formed into a film on an electrode of a substrate with an electrode, then the substrate with an electrode is laminated, and the liquid crystal substance is uniaxially aligned and then crosslinked. A method for manufacturing a liquid crystal optical element, which comprises performing a treatment. 3. The method for producing a liquid crystal optical element according to claim 2, wherein the substrate is a thermoplastic resin plate, and the uniaxial orientation is performed by bending deformation.