JPH08240796A - Liquid crystal composition, liquid crystal element using same and its production - Google Patents

Abstract

PURPOSE: To provide a liquid crystal element having excellent strength against pressing force and the like and excellent display characteristics, and to provide a liquid crystal compsn. and its production method for the liquid crystal element. CONSTITUTION: A liquid crystal compsn. comprising a liquid crystal and a macromonomer which is separated from the liquid crystal phase and does not respond to an electric field is held between a pair of electrode substrates 1 at least one of which is transparent. After the phasel separation between the liquid crystal and the macromonomer is promoted by heating, the liquid crystal is horizontally oriented to obtain a liquid crystal element having a liquid crystal layer 3 comprising a liquid crystal region which is horizontally oriented and a macromonomer region which is separated from the liquid crystal phase and dispersed. Or a liquid crystal compsn. comprising a liquid crystal, a macromonomer which is separated from the liquid crystal in phase and does not respond to an electric field, and a polymn. initiator is held between a pair of electrode substrates at least one of which is transparent. After the phase separation between the liquid crystal and the macromonomer is promoted by heating, the liquid crystal is horizontally oriented. The macromonomer is then polymerized with the polymn. initiator to obtain a liquid crystal element having a liquid crystal layer comprising a liquid crystal region which is horizontally oriented, a polymer region of the macromonomer which is separated from the liquid crystal phase and dispersed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is suitable for use as a liquid crystal display element, a liquid crystal storage element, a liquid crystal acoustic element, a light control glass, and the like, a liquid crystal element suitably used in the field of optoelectronics, a manufacturing method thereof, and a liquid crystal material thereof. The present invention relates to a liquid crystal composition used in.

[0002]

2. Description of the Related Art A liquid crystal element is usually manufactured by a method of injecting a liquid crystal material between glass substrates. But,
When a glass substrate is used, there is a problem that it is difficult to increase the area of the device and the yield is poor. A method of using a flexible material such as a plastic film as a substrate has also been proposed. In this method, a series of continuous processes such as formation of a liquid crystal layer by a film forming method, lamination with a counter substrate, and bending alignment can be used. Therefore, a large-screen liquid crystal element can be easily manufactured with high productivity. However, in the obtained liquid crystal element, since the substrate has flexibility and the liquid crystal itself has poor shape retention, the strength is not sufficient by itself,
There is a problem that a conduction defect is likely to occur due to pressing or the like.

Therefore, in order to solve this problem, it is considered to add a reinforcing material to the liquid crystal material. As a practical method of manufacturing a liquid crystal element using a reinforcing material, the following four types of proposals have been roughly classified.

(1) Method of impregnating a porous polymer with a liquid crystal (HG Craighead, J. Chen)
g and S. Hackwood, Appl.
Phys. Lett, 40, 22 (198
2). ).

(2) A method in which a liquid crystal is dispersed in an aqueous solution of a water-soluble polymer and cast (J. L. Fergason,
SID '85 Digest, 68 (199
0). ).

(3) Method of dissolving liquid crystal and polymer in a common solvent and casting (T. Kajiyama, AM
iyasato, H .; Kikuchi and
Y. Morimura, Chem. Lett. ，
813 (1989). ).

(4) A method of preparing a mixture of a liquid crystal and a polymerizable compound and carrying out a polymerization reaction by light or heat to cause phase separation of the liquid crystal and the polymer (J. W. Doane,
N. A. Vaz, B.A. G. Wu and S.
Zumer, Appl. Phys. Lett. ，
48, 269, (1985), N. et al. A. Va
z, G.G. W. Smith and Jr P.M.
Montgomery, Molecular Cry
stall and Liquid Crystal,
146, 1, (1987), Y. Hirai,
S. Niiyama, Y .; Kumai and
T. Gunjima, Polym. Prep
r. Jpn. 38, 2151 (1989). ).

However, the above (1), (2),
The method (3) has a problem that it is difficult to perform horizontal alignment processing of liquid crystals due to shear stress.

As a concrete method of the above (4), it has been proposed to use an adhesive as a reinforcing material (Japanese Patent Laid-Open No. HEI 2).
-36299, Japanese Patent Laid-Open No. 2-219861). In this case, it is possible to cure after the horizontal orientation treatment by shear stress, but due to ionic impurities generated during the curing reaction of the adhesive, or the change over time in the shape of the adhesive part, it is possible to display after the curing reaction. There is a problem that the characteristics deteriorate. Examples of deterioration of display characteristics include burn-in, disordered orientation, reduced contrast, and coloring.

Particularly, in the case of a liquid crystal element using a ferroelectric liquid crystal material, there is a problem that the bistability after the curing reaction of the adhesive is significantly reduced.

[0011]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a liquid crystal element having excellent display characteristics as well as strength against pressure and the like, a liquid crystal composition used for its production, and a production method. .

[0012]

DISCLOSURE OF THE INVENTION As a result of studies conducted by the present inventors in order to solve the above problems, the use of a macromonomer as a reinforcing material for a liquid crystal material results in deterioration of display characteristics after the curing reaction of the reinforcing material. It was found that a liquid crystal composition having a significantly improved ratio was obtained, and by producing a liquid crystal element using the liquid crystal composition, a liquid crystal element having excellent strength against pressure and the like and excellent display characteristics was obtained. The invention was completed.

That is, the present invention is a liquid crystal composition comprising a liquid crystal and a macromonomer, wherein the macromonomer is phase separated from the liquid crystal to form a region in the liquid crystal composition that does not respond to an electric field. And a liquid crystal composition (hereinafter, sometimes referred to as liquid crystal composition 1).

The present invention also provides a liquid crystal composition comprising a liquid crystal, a macromonomer and a polymerization initiator for the macromonomer, wherein the macromonomer undergoes phase separation from the liquid crystal,
A liquid crystal composition (hereinafter referred to as liquid crystal composition 2) characterized in that it forms a polymer region of a macromonomer which does not phase-separate from the liquid crystal after polymerization and does not respond to an electric field in the liquid crystal composition. May be provided.)

Further, according to the present invention, a liquid crystal element produced by using the above liquid crystal composition 1 as a liquid crystal material, that is, a pair of substrates with electrodes, at least one of which is transparent, and a liquid crystal layer sandwiched between the substrates. In the liquid crystal element, the liquid crystal layer is formed by using the liquid crystal composition 1,
The liquid crystal layer is composed of a liquid crystal region and a region of macromonomer phase-separated from the liquid crystal and dispersed in the liquid crystal layer, and the liquid crystal is horizontally aligned (hereinafter, referred to as liquid crystal device 1 Sometimes called).

The present invention also provides a method for producing the liquid crystal element 1, that is, a step of sandwiching the liquid crystal composition 1 between a pair of substrates with electrodes, at least one of which is transparent, and the sandwiched liquid crystal composition. By heating the liquid crystal to a temperature at which the liquid crystal is in the isotropic phase state or the liquid crystal state and then cooling the liquid crystal to a temperature below room temperature, a macromonomer that does not respond to the electric field is dispersed in the liquid crystal layer by phase separation from the liquid crystal region and the liquid crystal. Provided is a method for producing a liquid crystal element 1, comprising a step of forming a liquid crystal layer composed of a region between substrates with electrodes, and a step of horizontally aligning liquid crystals in the liquid crystal layer.

Furthermore, the present invention is a liquid crystal device manufactured by using the liquid crystal composition 2, that is, a liquid crystal device comprising a pair of substrates with electrodes, at least one of which is transparent, and a liquid crystal layer sandwiched between the substrates. In, the liquid crystal layer is formed by using the liquid crystal composition 2, and the liquid crystal and the macromonomer polymer are dispersed in the liquid crystal region and the liquid crystal layer and do not respond to the electric field. The liquid crystal device is characterized in that it is phase-separated into a macromonomer polymer region, the macromonomer polymer is formed by polymerization using a polymerization initiator, and the liquid crystal is horizontally aligned. provide.

The present invention also provides a method for producing the liquid crystal element 2, that is, a step of sandwiching the liquid crystal composition 2 between a pair of substrates with electrodes, at least one of which is transparent, and the sandwiched liquid crystal composition. In the liquid crystal layer and the liquid crystal layer, where the liquid crystal and the macromonomer are phase-separated by heating the liquid crystal to a temperature at which the liquid crystal is in the isotropic phase state or the liquid crystal state and then cooling the temperature to around room temperature or lower. A step of forming a liquid crystal layer composed of a region of macromonomers dispersed in the substrate between the substrates with electrodes, a step of horizontally aligning the liquid crystal in the liquid crystal layer,
And a step of polymerizing a macromonomer in a macromonomer region in the liquid crystal layer to form a macromonomer polymer region that does not respond to an electric field.

(1) Liquid Crystal Composition The liquid crystal composition of the present invention comprises liquid crystal and macromonomer (liquid crystal composition 1) or liquid crystal and macromonomer and polymerization initiator of macromonomer (liquid crystal composition 2). The macromonomer used in the present invention is such that the polymer itself and the polymer thereof are phase-separated from the liquid crystal to form a region in the liquid crystal composition that does not respond to an electric field. (1) -1: Liquid crystal Used in the present invention The liquid crystal is not particularly limited as long as it responds to the application of an electric field, and for example, nematic liquid crystal, chiral nematic (cholesteric) liquid crystal, ferroelectric liquid crystal, antiferroelectric liquid crystal, or smectic C liquid crystal is preferably used. To be In addition, these liquid crystals may be low molecular weight liquid crystals or high molecular weight liquid crystals as long as they form a liquid crystal region by phase separation with the macromonomer used in the present invention or the macromonomer and its polymer. Good. In addition, these liquid crystals may be used alone or in a suitable mixture of two or more kinds depending on the application.

The following are some specific examples of the liquid crystal preferably used in the present invention. [Specific examples of nematic low-molecular liquid crystals]

[0021]

Embedded image [Specific examples of cholesteric low-molecular liquid crystals]

[0022]

Embedded image [Specific examples of ferroelectric low-molecular liquid crystals]

[0023]

Embedded image [Specific examples of antiferroelectric low-molecular liquid crystals]

[0024]

[Chemical 4] [Specific examples of smectic C (SmC) low-molecular liquid crystal]

[0025]

Embedded image [Specific examples of nematic polymer liquid crystals]

[0026]

[Chemical 6] [Specific examples of cholesteric polymer liquid crystals]

[0027]

[Chemical 7] [Specific Examples of Smectic C (SmC) Polymer Liquid Crystal]

[0028]

Embedded image [Specific examples of ferroelectric polymer liquid crystal]

[0029]

[Chemical 9]

[0030]

[Chemical 10] (1) -2: Macromonomer As the macromonomer used in the present invention, the macromonomer itself, or the macromonomer itself and the polymer thereof undergo phase separation from the liquid crystal in the liquid crystal composition, and Any known material can be used without particular limitation as long as it forms a region.

When the macromonomer is used as a reinforcing material, the liquid crystal element itself can be provided with strength against pressure or the like. Further, by polymerizing the macromonomer, further excellent strength can be obtained. In the conventional technology that uses an adhesive that cures by cross-linking as a reinforcing material, the shape of the adhesive part after curing changes with time and the display characteristics after the curing reaction deteriorate at the interface between the liquid crystal and the adhesive part. There was a problem of doing. However, in the case of macromonomer, the phase separation is better than that of ordinary adhesives,
The change of the interface with time is small, and when the polymerization is performed, the change of the shape with time is also small because it is due to the polymerization of the polymerizable functional group at the molecular end. For these reasons, deterioration of display characteristics is reduced.

The molecular weight of the macromonomer is usually
Those having a number average molecular weight of 1,000 to 100,000, preferably 3,000 to 10,000 are suitably used. If the number average molecular weight is lower than 1,000, the solubility of the macromonomer in the liquid crystal may be increased, and phase separation may be difficult. The number average molecular weight is 100,
If it is higher than 000, the glass transition temperature of the macromonomer or its polymer becomes high, and the orientation of the liquid crystal due to shearing force may become difficult. Considering the good phase separation from the liquid crystal, the ease of alignment, and the panel strength after alignment, the molecular weight is more preferably 3,000 to 10,000.

The macromonomer comprises a polymer portion and a polymerizable functional group bonded to the end of the polymer portion. Examples of the macromolecular portion of the macromonomer used in the present invention include polystyrene (PSt) and polyisoprene (PI).
p), poly-2-vinylpyridine (PVP), polyisobutylene (PIB), polymethylmethacrylate (PM
MA), polyethylene oxide (PEO), polytetrahydrofuran (PTHF), polydimethylsiloxane (PDMS), poly-t-butylaziridine (PTB)
A), polyoxazolidine (POXZ), styrene-acrylonitrile copolymer, polybutyl acrylate,
Examples thereof include polydimethyl siloxane.

Examples of the terminal polymerizable functional group of the macromonomer used in the present invention include vinyl group, styryl group, methacryloyl group, dihydroxyl group and dicarboxyl group.

In the present invention, macromonomer 1
Only one species may be used, or two or more species may be appropriately used in combination.

Specific examples of the macromonomer preferably used in the present invention are shown below. As the value of n in each structural formula, the number average molecular weight of each macromonomer is 1,000 to
A value of 100,000 is suitable. Specific examples of macromonomers

[0037]

[Chemical 11]

[0038]

[Chemical 12]

[0039]

[Chemical 13]

[0040]

Embedded image (1) -3 Composition of Liquid Crystal Composition In the liquid crystal compositions 1 and 2 of the present invention, the ratio of the macromonomer to the entire liquid crystal composition is preferably 1 to 50.
%, More preferably 3 to 30% by weight. When a liquid crystal panel is manufactured using a liquid crystal composition in which the proportion of macromonomer is less than 1% by weight, sufficient strength may not be obtained. The proportion of macromonomer is 50% by weight.
When it exceeds, the display quality may deteriorate when displaying in the birefringence mode. In order to surely obtain both characteristics of sufficient panel strength and good display quality, it is desirable that the proportion of the macromonomer is 3 to 30% by weight.

The liquid crystal composition 1 of the present invention comprises a liquid crystal and a macromonomer. By using this liquid crystal composition 1 in the production of a liquid crystal panel, a liquid crystal panel having sufficient strength can be obtained. The liquid crystal composition 2 further contains a polymerization initiator of a macromonomer, and the liquid crystal and the macromonomer are phase-separated in the liquid crystal panel and then the macromonomer is polymerized to obtain a liquid crystal panel excellent in strength. it can.

As described above, when polymerizing the macromonomer in the liquid crystal device, a polymerization initiator is added to the liquid crystal composition of the present invention in addition to the liquid crystal and the macromonomer. The polymerization initiator used in the present invention is not particularly limited and can be appropriately selected and used according to the type of polymerization reaction, the type of polymerizable functional group of the macromonomer, and the like.
For example, when polymerizing a macromonomer by radical polymerization, 2,2-dimethoxy-
1,2-diphenylethan-1-one, 1-hydroxycyclohexyl = phenyl = ketone, 2-methyl-1-
[4- (Methylthio) phenyl] -2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) butan-1-one, 2-hydroxy-2-methyl -1-Phenylpropan-1-one, 1- [4- (2-hydroxyethoxy)
Phenyl] -2-hydroxy-2-methyl-1-propan-1-one and the like, and as the thermal polymerization initiator, cumene hydroperoxide, t-butyl hydroperoxide,
Dicumyl peroxide, di-t-butyl peroxide,
Benzoyl peroxide, lauroyl peroxide, potassium persulfate, azobisisobutyronitrile, hydrogen peroxide-ferrous iron salt, persulfate-sodium acid sulfite, cumene hydroperoxide-ferrous iron salt, benzoyl peroxide-dimethyl Aniline, peroxide (hydrogen peroxide, hydroperoxide, etc.)-Organometallic alkyl (triethylaluminum, triethylboron, diethylzinc, etc.), oxygen-organometallic alkyl, etc. are used. The ratio of the polymerization initiator to be added cannot be unconditionally specified because it depends on the reactivity of the macromonomer in the liquid crystal, but it is usually 1 to the macromonomer.
-5% by weight, preferably 2-3% by weight.

When a liquid crystal device is manufactured using the liquid crystal composition of the present invention, the liquid crystal and the macromonomer are usually phase-separated before the alignment treatment. At that time, heating may be performed to promote phase separation. When the polymerizable functional group of the macromonomer is radically polymerizable and the polymerization initiator is a compound that generates a radical by ultraviolet rays (UV), the heat treatment may start the polymerization of the macromonomer. If polymerization starts at this point and the macromonomer becomes high in molecular weight, the glass transition temperature becomes high, and orientation due to shearing force may become difficult.
Therefore, when adding a polymerization initiator to the liquid crystal composition,
If necessary, a suitable polymerization inhibitor may be added.

Examples of the polymerization inhibitor include hydroquinone, paraquinone, and bis (1,2,2,6,6) sebacate.
-Pentamethyl-4-piperidyl) and the like are preferably used. The amount of the polymerization inhibitor is usually 0.1 to 0.5% by weight, preferably 0.2 to 0.4, based on the macromonomer.
% By weight.

A dichroic dye may be added to the liquid crystal composition of the present invention. Examples of the dichroic dye include anthraquinone dyes, azo dyes, merocyanine dyes, styryl dyes, azomethine dyes, and tetrazine dyes.

(2) -1 Liquid Crystal Element FIG. 1 shows a partial sectional view of one mode of the liquid crystal element (liquid crystal element 1 or 2) of the present invention. As shown in FIG. 1, the liquid crystal element of the present invention includes a pair of electrodes 2 at least one of which is transparent.
A liquid crystal layer 3 formed by using the liquid crystal composition of the present invention is sandwiched between the attached substrates 1 in contact with the electrode surface of the substrate 1.

Among the liquid crystal elements of the present invention, the above liquid crystal element 1
The liquid crystal layer of No. 1 is formed by using the liquid crystal composition 1, and includes a liquid crystal region and a region of macromonomer phase-separated from the liquid crystal and dispersed in the liquid crystal layer. On the other hand, the liquid crystal layer of the liquid crystal element 2 is formed by using the liquid crystal composition 2, and the liquid crystal layer has a liquid crystal region and an electric field response that is phase-separated from the liquid crystal and dispersed in the liquid crystal layer. Not composed of macromonomer polymer regions.

That is, in the liquid crystal element of the present invention,
The liquid crystal and macromonomer, or the polymer of liquid crystal and macromonomer, are phase-separated from each other and have their respective domains
Is formed. The region formed of the macromonomer or the polymer of the macromonomer forms a penetrating region connected to the upper and lower substrates with electrodes.

In the liquid crystal element of the present invention, the liquid crystal in the liquid crystal layer is horizontally aligned, and the arrangement is changed by the application of an electric field, and one or two polarizing plates are arranged outside the substrate to display a bright and dark display. Is possible.

The substrate used in the present invention can be used without particular limitation as long as it can form an electrode, such as glass or plastic. Examples of materials for the plastic substrate include crystalline polymers such as uniaxially or biaxially oriented polyethylene terephthalate (PET), non-crystalline polymers such as polysulfone (PS) and polyethersulfone (PES), polyolefins such as polyethylene and polypropylene, and the like. Examples thereof include polyarylate (PAr), polycarbonate (PC), and polyamide such as nylon. From the viewpoint of high productivity of the liquid crystal element, it is preferable to use a flexible substrate such as a plastic film. The thickness of the substrate is usually 100 μm to 1 mm, preferably 100 μm to 500 mm.

In the present invention, the two substrates with electrodes may be made of the same material or different materials, but at least one substrate is optically transparent. In this case, an optically transparent or semitransparent electrode is provided for use.

Specific examples of the transparent or semi-transparent electrode include, for example, a tin oxide film called an NESA film, an indium oxide film, an ITO film made of a mixture of indium oxide and tin oxide, a vapor deposition film of gold, titanium or the like. , Or other thin film metal or alloy such as aluminum. The shape of these electrodes is not particularly limited, and may be the entire surface on a predetermined surface of the substrate, the stripe shape, or any other desired shape. .

The thickness of the liquid crystal layer is usually 0.5 to 10 μm.
m, preferably about 1 to 3 μm.

FIG. 2 is a partial sectional view showing another example of the liquid crystal element of the present invention. An insulating film 4 is provided between the substrate 1 with the two electrodes 2 and the liquid crystal layer 3. Spacers 5 are arranged in the liquid crystal layer 3 to keep the cell gap between the electrodes constant and prevent a short circuit between the electrodes.

The spacer is not particularly limited as long as it is usually used in a liquid crystal element, and a spacer made of glass, silica or plastic having solvent resistance is preferably used. As the spacer, a spherical one is suitable for the method for producing a liquid crystal element by a continuous process and is preferably used. Specific examples of suitable materials for the spherical spacers include inorganic materials such as silica and divinylbenzene-based or polystyrene-based polymer beads. The particle size of the spherical spacer can be appropriately selected according to the cell thickness of the liquid crystal element, and is usually preferably about 1 to 5 μm. If the cell gap can be maintained without using the spacer, the spacer may not be used.

The insulating film is for preventing a short circuit between the opposing electrodes, and if there is no risk of short circuit, the insulating film may not be provided. The material of the insulating film is not particularly limited as long as it is usually used for a liquid crystal element, and examples thereof include inorganic vapor-deposited films such as SiO _x , various non-liquid crystalline polymer films such as acrylic, nylon and epoxy. Is mentioned.

Further, in the liquid crystal element of the present invention, an alignment film may be provided in contact with the liquid crystal layer, if necessary. The alignment film is not particularly limited as long as it is usually used for a liquid crystal element, and various kinds such as a polymer film such as polyimide or polyvinyl alcohol rubbed in one direction, or a film obtained by obliquely depositing silicon oxide can be used. An alignment film can be used. The alignment film may not be provided in the case where the liquid crystal element is aligned by a bending stress, a shear stress applied to the liquid crystal due to displacement of the upper and lower substrates, or an alignment method by applying a shear stress and a voltage.

The liquid crystal element of the present invention is preferably sealed so that the liquid crystal does not flow out of the element, but if there is no risk of the liquid crystal flowing out and the element can be kept stable, the liquid crystal element is sealed. You don't have to.

(3) Method of Manufacturing Liquid Crystal Element The liquid crystal elements of the present invention (liquid crystal elements 1 and 2) are preferably manufactured by the method of the present invention.

In the method for producing a liquid crystal element of the present invention, a step of sandwiching the liquid crystal composition (liquid crystal composition 1 or 2) of the present invention between a pair of substrates with electrodes, at least one of which is transparent, and the sandwiched liquid crystal. By heating the composition to a temperature at which the liquid crystal is in an isotropic phase state or a liquid crystal state, and then cooling it to a temperature near room temperature or lower, a liquid crystal region formed by phase separation of the liquid crystal and macromonomer is formed. The method for producing the liquid crystal element 2 includes the steps of forming a liquid crystal layer composed of regions of macromonomers dispersed in the liquid crystal layer between the substrates with electrodes, and horizontally aligning the liquid crystal in the liquid crystal layer. The method further includes the step of polymerizing the macromonomer in the macromonomer region in the liquid crystal layer to form a macromonomer polymer region that does not respond to an electric field.

(3) -1 Step of sandwiching liquid crystal composition between substrates with electrodes As a method of sandwiching the liquid crystal composition between substrates with electrodes,
There is no particular limitation, and it can be appropriately selected according to the properties of the liquid crystal composition, such as a vacuum injection method and a coating method on a substrate with an electrode. Usually, a method in which a liquid crystal composition is dissolved in a common solvent for all components to prepare a coating solution, which is applied to at least one of substrates with electrodes, and after evaporation of the solvent, both substrates are immediately laminated to each other is laminated. It is suitable.

The coating liquid is usually prepared at a concentration such that the viscosity becomes 1 to 3 cp. The concentration of the liquid crystal composition in the coating liquid is approximately 20 to 40% by weight in terms of weight percentage. The drying step of evaporating the solvent is usually carried out by heating at about 30 to 150 ° C. under normal pressure.

The solvent used for preparing the coating solution is
There is no particular limitation as long as it dissolves the liquid crystal composition without dissolving the substrate or the insulating film and the alignment film provided as necessary. Usually, acetone, methyl ethyl ketone, toluene,
Xylene, dichloromethane, chloroform, tetrahydrofuran, ethyl acetate, a mixed solvent thereof or the like is preferably used.

Before sandwiching the liquid crystal composition, if necessary,
An insulating layer or an alignment film may be formed on the substrate with electrodes. Further, when the spacer is arranged between the upper and lower substrates, the method of arranging the spacer is not particularly limited, and may be fixed on the electrode-attached substrate or between both substrates in advance,
You may mix in a liquid crystal composition or the said coating liquid, and may arrange | position simultaneously at the time of forming a liquid crystal layer. Alternatively, after applying the liquid crystal composition or its coating liquid, the liquid crystal composition or the coating liquid may be arranged on the coating layer and embedded and fixed.

(3) -2 Step of Phase Separation of Liquid Crystal and Macromonomer If the phase separation of the liquid crystal and macromonomer is good, it is possible to confirm the existence of the domain of the macromonomer which has already been phase separated from the liquid crystal after solvent evaporation. However, since the phase separation is not sufficient, the liquid crystal is heated to a temperature at which the liquid crystal is in the isotropic phase state (liquid crystal phase temperature), and then cooled to around room temperature or lower to separate the phase. Promote. The heating temperature and heating time cannot be unequivocally changed because they change depending on the phase transition temperature of the liquid crystal, the glass transition temperature of the macromonomer, the phase separation property of the liquid crystal and the macromonomer, etc.
The temperature is within 50 ° C., preferably within 30 ° C., before and after the phase transition temperature of the liquid crystal from the isotropic phase to the liquid crystal phase or from the liquid crystal phase to the isotropic phase for 1 to 120 minutes, preferably 1
Continue heating for ~ 30 minutes. If it is not heated once, phase separation does not occur sufficiently, and if the heating temperature is too high, the panel may be deformed or shear stress may not be applied after cooling.

Cooling to around room temperature or lower after heating can be said to be uncertain because it varies depending on how large a phase separation region is formed and how it is dispersed. Cool at a rate of about 10 ° C / min.

To further promote phase separation, an electric field may be applied to the liquid crystal composition layer during heating. The applied electric field is usually a voltage of 1 to 100 V and a frequency of 0.1 to 1
An alternating electric field of 000 Hz is used. As the waveform, a rectangular wave, a triangular wave, a sine wave, or the like is used.

As described above in the description of the liquid crystal composition, when the liquid crystal composition 2 is manufactured using the liquid crystal composition 2 containing the polymerization initiator, the polymerizable functional group of the macromonomer is radically polymerizable. And, when the polymerization initiator is a compound that generates radicals by ultraviolet rays, the above-mentioned heat treatment may already start the polymerization of the macromonomer. Therefore, when there is such a possibility, it is preferable to use the liquid crystal composition 2 to which the polymerization inhibitor is added.

(3) -4 Step of Horizontally Aligning Liquid Crystal After the above phase separation treatment, the liquid crystal in the liquid crystal layer is horizontally aligned. As a method of orientation, as in the case of producing a normal liquid crystal element, a method of shear stress due to a displacement between upper and lower substrates or a deflection of the liquid crystal element, a method of applying an electric field, a magnetic field orientation method, a temperature gradient method, SiO There is no particular limitation as long as horizontal alignment can be obtained, such as an oblique vapor deposition method, a rubbing method for an alignment film, and a combination thereof.

For example, when a flexible plastic substrate is used as the substrate, a method in which the liquid crystal element is flexibly deformed and a shear stress is applied to orient the liquid crystal element is preferably used. As a means for giving flexural deformation, a method of using at least one roll and bending the liquid crystal element along the roll surface is suitable. FIG. 3 shows one mode of such means. In the embodiment of FIG. 3, the unaligned liquid crystal element 6 is moved between the three rolls 7 while alternately contacting both surfaces with the rolls 7, and the liquid crystal in the liquid crystal element is horizontally aligned by the shear stress due to the flexural deformation. The aligned liquid crystal element 8 is obtained. When performing orientation by shear stress, in order to obtain better orientation, shear stress may be applied while applying an electric field between the upper and lower electrodes of the liquid crystal element, use of a heating roll, or the entire system of the device in a high temperature tank. It may be carried out while heating, for example. Depending on the type of macromonomer, there is a case where sufficient panel strength can be obtained at this stage without polymerizing, and the macromonomer region may grow more due to the alignment of the liquid crystal region.

(3) -5 Macromonomer Polymerization Step In the liquid crystal element of the present invention, in the method for producing the liquid crystal element 2 having a macromonomer polymer region in the liquid crystal layer, after the alignment step, The phase-separated macromonomer is polymerized. The polymerization reaction can be appropriately selected depending on the types of macromonomer and polymerization initiator.

For example, when the polymerizable functional group of the macromonomer is radically polymerizable and the polymerization initiator is a compound that generates radicals by ultraviolet rays (UV), the ultraviolet rays are irradiated to polymerize the macromonomers by the radical polymerization method. Let At this time, it may be performed while applying an electric field.

Polymerization is usually carried out at a temperature from around the isotropic phase-liquid crystal phase transition temperature to around room temperature at which the alignment of the liquid crystal is maintained. The UV intensity is set so that the substrate and the material do not deteriorate. Usually, it is 0.1 to 100 mW / cm ² . The irradiation time is usually 1 to 60 seconds. The applied electric field is usually
An alternating electric field having a voltage of 1 to 100 V and a frequency of 0.1 to 1000 Hz is used. As the waveform, a rectangular wave, a triangular wave, a sine wave, or the like is used.

During or after the polymerization step of the above-mentioned alignment step, heat treatment may be carried out for further phase separation, alignment restoration, or elimination of uneven thickness of the liquid crystal layer. At this time, an electric field may be applied.

[0075]

The present invention will be described in more detail below with reference to examples of the present invention and comparative examples thereof, but the present invention is not limited to these examples.

The liquid crystals and macromonomers described in the following Examples and Comparative Examples are those exemplified above as specific examples, and their numbers also correspond to the numbers given above.

Example 1 Preparation of coating solution Ferroelectric polymer liquid crystal, ferroelectric low-molecular liquid crystal, Sm
C A low molecular weight liquid crystal, a macromonomer, a polymerization initiator and a polymerization inhibitor were mixed in the following proportions, and methyl ethyl ketone (MEK) was further added thereto to prepare a 30% by weight MEK solution of a liquid crystal composition containing a macromonomer. .

Ferroelectric polymer liquid crystal (45) (Mn = 2100) 1.5 g Ferroelectric low molecular liquid crystal (13) 0.6 g SmC low molecular liquid crystal (21) 0.3 g (22) 0.3 g (23 ) 0.3 g Macromonomer (d) (Mn = 6000) 0.3 g Polymerization initiator (Irgacure 369 manufactured by Ciba-Geigy) 0.012 g Polymerization inhibitor (hydroquinone) 0.0024 g This solution becomes a completely clear solution. After visually confirming that the coating solution is present, the solution was filtered through a 0.45 μm polytetrafluoroethylene (PTEE) membrane filter and poured into a glass container containing a silica spacer having a particle size of 2.1 μm in advance to prepare a coating solution. .

The ferroelectric polymer liquid crystal (45),
Ferroelectric low-molecular liquid crystal (13), SmC low-molecular liquid crystal (2
The phase transition behavior (determined by observation with a polarizing microscope) of the liquid crystal composed of the mixture of 1), (22) and (23) in the above amounts was as follows.

[0080]

[Chemical 15] Example 2 Preparation of Device An insulating film was previously formed on the surface [film type: epoxy adhesive (mixture of 1: 1 weight ratio mixture of Cemedine 1590 and Epicoat YL-979 manufactured by Yuka Shell Epoxy Co., Ltd.), thickness: 0.
1 μm], and a sufficiently dried polyether sulfone (PES) substrate with an ITO electrode (width 14 cm, length 70 cm) was coated with the macromonomer-containing liquid crystal composition using the coating solution prepared in Example 1. Was applied. Immediately after the evaporation of the solvent, the same kind of PES substrate with an ITO electrode having the same insulating film as the above was attached and laminated.

The length 3 of the liquid crystal element manufactured in this way
A 0 cm portion was cut out and placed in an oven at 92 ° C. for 8 minutes to promote phase separation between liquid crystal and macromonomer. Then, it was gradually cooled to 25 ° C. over 20 minutes. Add this to 73
± 50 V AC (square wave, 10
While applying an electric field of 3 Hz, three rolls arranged in parallel as shown in FIG. 3 (roll material: stainless steel, diameter: 3.6 cm, roll length: 30 cm, roll interval:
The liquid crystal element was subjected to uniaxial horizontal alignment treatment by subjecting the liquid crystal element to a flexural deformation in a fixed direction. At this time, the moving speed of the element in the horizontal direction was set to 1 m / min. A liquid crystal element that had been subjected to such alignment treatment was subjected to an alternating current of ± 30 under crossed Nicols.
While applying an electric field of V (rectangular wave, 10 Hz), the liquid crystal element was rotated so that the contrast of bright and dark display was maximized. When the bistability (M value) was evaluated in that state,
M = 97%.

The panel strength was 14 mm in the bending test.

The evaluation of bistability (M value measurement) was carried out as follows.

That is, as shown in FIG. 4, a bipolar pulsed voltage (9 and 11) is applied between the upper and lower electrodes of the liquid crystal element to apply an electric field to the liquid crystal to change the transmitted light intensity (10 and 1).
2) is measured. FIG. 5 is a graph in which graphs 10 and 12 showing the change in transmitted light intensity shown in FIG. The difference in the intensity of transmitted light between light and dark when an electric field is applied is a
And the difference in brightness between 0.5 seconds after applying the pulsed electric field is b
And The ratio M of b to a is M = (b / a) × 1
Expressed as a percentage by the formula of 00 (%). The best bistability results in M = 100%, and the worst bistability results in M = 0%. Here, as the pulsed electric field, an electric field having a pulse width of 2 ms and a voltage of ± 30 V was applied.
Also, the value of 0.5 seconds is 2 ms × 2 × 96 lines ≈
In addition to 0.4 seconds of 0.4 seconds, it was set in consideration of the change in conditions during actual driving.

The bending test was conducted as follows. That is, as shown in FIG. 6, a step of 3 mm is formed on the glass plate 13, the liquid crystal element 14 is placed on the step so that the shear alignment direction is parallel to the edge of the step, and the stainless steel ruler 15 is pressed in parallel with the step. Then, the liquid crystal element 14 was bent, and the strength was evaluated visually by the distance (c) when the alignment was broken.

Further, this element was subjected to an alternating current of ± 50 V at room temperature.
While applying an electric field of (rectangular wave, 20Hz), HOYA
-UV (ultraviolet) irradiation was performed using a desktop UV light source manufactured by SCHOTT to polymerize the macromonomer. The irradiation conditions were an intensity of 63 mW / cm ² for 4 seconds. After UV irradiation, the bistability (M value) was evaluated in the same manner as above.
= 77%.

Further, the fact that the macromonomer or the polymerized macromonomer and the liquid crystal are phase separated means that
It was confirmed by observing with a polarizing microscope that there was a region that did not respond when an electric field was applied to the device.
Here, it was confirmed that, after the alignment treatment and after the UV irradiation, regions having a particle size of 4 to 20 μm that did not respond to the electric field were scattered in the cell.

The panel strength in the bending test was 11 mm.

Example 3 Preparation of coating solution Ferroelectric polymer liquid crystal, ferroelectric low molecular liquid crystal, Sm
C low molecular weight liquid crystal (low molecular weight liquid crystal having smectic C phase), macromonomer, polymerization initiator and polymerization inhibitor,
Using the following proportions, a coating solution containing a liquid crystal, a macromonomer, a polymerization initiator, a polymerization inhibitor and a spacer was prepared in the same manner as in Example 1.

Ferroelectric polymer liquid crystal (45) (Mn = 2100) 1.5 g Ferroelectric low molecular liquid crystal (13) 0.6 g SmC low molecular liquid crystal (21) 0.3 g (22) 0.3 g (23 ) 0.3 g Macromonomer (j) (Mn = 6000) 0.3 g Polymerization initiator (manufactured by Ciba-Geigy, Irgacure 369) 0.012 g Polymerization inhibitor (hydroquinone) 0.0024 g Example 4 Preparation of element In Example 3 An element was produced in the same manner as in Example 2 using the prepared coating solution. Bistability after orientation treatment is M = 95
%, And the bistability after UV irradiation was M = 67%. In addition, after the alignment treatment and the irradiation of ultraviolet rays, the particle diameter of 4 to
It was confirmed that 20 μm electric field non-responsive regions were scattered.

The panel strength was 15 mm before the polymerization and 13 mm after the polymerization.

Example 5 Preparation of coating solution Ferroelectric polymer liquid crystal, ferroelectric low molecular liquid crystal, Sm
C low molecular weight liquid crystal (a low molecular weight liquid crystal having a smectic C phase and a macromonomer were used in the following proportions, and a 30% MEK solution of a liquid crystal composition containing a liquid crystal, a macromonomer and a spacer was prepared in the same manner as in Example 1. A coating solution consisting of a spacer was prepared.

Ferroelectric polymer liquid crystal (45) (Mn = 2100) 1.5 g Ferroelectric low molecular liquid crystal (13) 0.6 g SmC low molecular liquid crystal (21) 0.3 g (22) 0.3 g (23 ) 0.3 g Macromonomer (b) (Mn = 6000) 0.3 g Example 6 Preparation of device Using the coating solution prepared in Example 5, heat treatment and uniaxial horizontal alignment treatment were performed in the same manner as in Example 2. A device was produced. The bistability after the orientation treatment was M = 93%, and the panel strength evaluated by the bending test was 13 mm. It was also confirmed that, after the alignment treatment, regions having a particle size of 9 to 20 μm and not responding to an electric field were scattered in the cell.

Comparative Example 1 Preparation of Coating Solution For comparison, an ordinary UV curable adhesive (manufactured by ThreeBond, product name 3026) was used in the following proportions to prepare a ferroelectric polymer liquid crystal and a ferroelectric low molecule. After mixing the liquid crystal, the SmC low molecular weight liquid crystal and the UV curable adhesive 3026, in the same manner as in Example 1, a 30% MEK solution of the liquid crystal composition containing the liquid crystal, the UV curable adhesive and the spacer and the spacer are formed. A coating solution was prepared.

Ferroelectric polymer liquid crystal (45) (Mn = 2100) 1.5 g Ferroelectric low molecular liquid crystal (13) 0.6 g SmC low molecular liquid crystal (21) 0.3 g (22) 0.3 g (23 ) 0.3 g UV curable adhesive (manufactured by ThreeBond Co., Ltd., 3026) 0.3 g Comparative Example 2 Preparation of Element Using the coating solution prepared in Comparative Example 1, an element was prepared in the same manner as in Example 2. Bistability after orientation treatment is M = 98
%, And the bistability after UV irradiation was M = 8%.

The panel strength was 26 mm before the polymerization and 4 mm after the polymerization.

From the above Examples and Comparative Examples, it is understood that the bistability after UV irradiation is better when the macromonomer is used than when the ordinary UV-curable adhesive is used. The liquid crystal elements obtained in the examples also show excellent panel strength against pressure.

[0098]

Since the liquid crystal composition of the present invention contains a macromonomer as a reinforcing material, when a liquid crystal element having a liquid crystal layer in which a liquid crystal and a macromonomer are phase-separated using the same is produced, It is possible to obtain a liquid crystal element having excellent panel strength and excellent display characteristics. Further, by polymerizing the macromonomer in the liquid crystal element, a liquid crystal element is obtained which is further excellent in panel strength and in which the deterioration rate of display characteristics after the polymerization reaction is remarkably improved. Furthermore, in the method for producing a liquid crystal device of the present invention, before the alignment treatment of the liquid crystal and the polymerization of the macromonomer, the liquid crystal composition in the cell is heated to sufficiently phase separate the liquid crystal and the macromonomer, and Growing areas of monomer. Therefore, the obtained liquid crystal element has excellent display characteristics and panel strength against pressure and the like.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view showing one embodiment of a liquid crystal element of the present invention.

FIG. 2 is a partial cross-sectional view showing another aspect of the liquid crystal element of the present invention.

FIG. 3 is a diagram illustrating a method of aligning a liquid crystal element.

FIG. 4 is a graph showing a bipolar pulsed electric field and a change in transmitted light intensity when the pulsed electric field is applied to a liquid crystal element.

5 is a graph obtained by superimposing two graphs showing the change in transmitted light intensity shown in FIG.

FIG. 6 is an explanatory diagram showing a method for evaluating the panel strength of a liquid crystal element.

[Explanation of symbols]

 1 substrate 2 electrode 3 liquid crystal layer 4 insulating film 5 spacer 6 unaligned liquid crystal element 7 roll 8 aligned liquid crystal element 9 pulse voltage 10 transmitted light intensity 11 pulse voltage 12 transmitted light intensity 13 glass plate 14 liquid crystal element 15 stainless steel ruler

Claims (9)

[Claims] 1. A liquid crystal composition comprising a liquid crystal and a macromonomer, wherein the macromonomer phase-separates from the liquid crystal to form a region in the liquid crystal composition that does not respond to an electric field. Stuff. 2. A liquid crystal composition comprising a liquid crystal, a macromonomer and a polymerization initiator for the macromonomer, wherein the macromonomer undergoes phase separation with the liquid crystal, and also undergoes phase separation with the liquid crystal even after the polymerization, resulting in an electric field response. A liquid crystal composition, wherein a region of a polymer of a macromonomer that does not exist is formed in the liquid crystal composition. 3. The liquid crystal composition according to claim 1, wherein the liquid crystal is a ferroelectric liquid crystal and the macromonomer has a number average molecular weight of 1,000 to 100,000. 4. The liquid crystal composition according to claim 2, wherein the macromonomer has a radically polymerizable polymerizable functional group at the molecular end, and the polymerization initiator is a radical polymerization initiator. 5. A liquid crystal element comprising a pair of substrates with electrodes, at least one of which is transparent, and a liquid crystal layer sandwiched between the substrates, wherein the liquid crystal layer is formed by using the liquid crystal composition according to claim 1. And the liquid crystal layer is a liquid crystal region,
A liquid crystal element comprising a liquid crystal and a macromonomer region that is phase-separated and dispersed in a liquid crystal layer, in which the liquid crystal is horizontally aligned. 6. A liquid crystal element comprising a pair of substrates with electrodes, at least one of which is transparent, and a liquid crystal layer sandwiched between the substrates, wherein the liquid crystal layer is formed by using the liquid crystal composition according to claim 2. In the liquid crystal layer, the polymer of the liquid crystal and the macromonomer is phase-separated into the liquid crystal region and the region of the macromonomer polymer which does not respond to the electric field dispersed in the liquid crystal layer. A liquid crystal device in which a polymer of a monomer is formed by polymerization using a polymerization initiator, and liquid crystals are horizontally aligned. 7. A step of sandwiching the liquid crystal composition according to claim 1 between a pair of substrates with electrodes, at least one of which is transparent, wherein the sandwiched liquid crystal composition is in an isotropic phase state or a liquid crystal state. A liquid crystal layer composed of a liquid crystal region and a region of macromonomer having no electric field response dispersed in the liquid crystal layer by being phase-separated from the liquid crystal by being heated to a temperature and then cooled to a temperature around room temperature or lower. 5. The method for producing a liquid crystal element according to claim 4, which comprises a step of forming a liquid crystal between the substrates with electrodes, and a step of horizontally aligning the liquid crystal in the liquid crystal layer. 8. A step of sandwiching the liquid crystal composition according to claim 2 between a pair of substrates with electrodes, at least one of which is transparent, and the sandwiched liquid crystal composition has a liquid crystal in an isotropic phase state or a liquid crystal state. After heating to a temperature, the liquid crystal region and the macromonomer region are separated from each other by cooling the liquid crystal region and the macromonomer into a liquid crystal region and a macromonomer region dispersed in the liquid crystal layer. Forming a liquid crystal layer between the substrates with electrodes, horizontally aligning liquid crystal in the liquid crystal layer, and polymer region of macromonomer that does not respond to electric field by polymerizing macromonomer in the liquid crystal layer 5. The method for manufacturing a liquid crystal element according to claim 4, comprising the step of forming. 9. The method according to claim 8, wherein the macromonomer is polymerized by radical polymerization.