JP2700656B2 - Fixed membrane - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a fixed membrane in which an electrode is attached to a polymer composite membrane containing a functional low molecule.

(Prior Art) Today, liquid crystals are used in various fields. A characteristic of liquid crystals is that the molecular arrangement is easily changed by optical anisotropy and external fields such as electric and magnetic fields. In particular, in a ferroelectric liquid crystal, a torque generated by an interaction between spontaneous polarization and an electric field serves as a driving force, and the driving force is extremely large, and is attracting attention as a high-speed display element material. Also, some dyes have excellent optical characteristics such as an electro-optical effect due to a normal electric or photoelectric field and a non-linear optical effect. These functional low-molecular liquid crystals and dyes have various molecular design possibilities and various optical characteristics, but have fluidity and have a problem in fixing the structure.

In a conventional optical display device, functional low molecules such as liquid crystal are fixed between two glass plates to fix the functional low molecules. However, using a glass plate causes problems in terms of flexibility, weight reduction, and area increase. For this reason, a method of fixing a functional polymer using a polymer that is flexible, lightweight, and easy to increase in area is generally considered. Among polymers, ferroelectric polymers have excellent electrical properties such as high dielectric constant, high-speed switching, piezoelectricity, pyroelectricity, and electrostriction. Therefore, a liquid crystal and / or a composite film of a dye and a polymer obtained by compounding a low-molecular substance and a polymer, which have both functions, have various functions in addition to the electro-optic effect and the nonlinear optical effect of the starting material. It is promising as a wide variety of industrial materials such as devices such as optical elements such as switches and memories, second harmonic generation (of semiconductor lasers), optical bistable memories, and optical processing. Conventionally known methods for obtaining a composite film of liquid crystal and a polymer include the following two methods.

(1) A method of casting a mixed solution of a liquid crystal and a polymer by a conventional method (solvent evaporation method), that is, a method of forming a polymer such as polyvinyl chloride or polycarbonate and N- (4-ethoxybenzylidene) -4 '. -Butylaniline, butyl-
4- (4-ethoxyphenoxycarbonyl) phenyl-
A method of dissolving a liquid crystal such as carbonate in a common solvent, uniformly casting the mixed solution in a petri dish, and evaporating the solvent to form a film; and (2) a water surface development method, that is, a liquid crystal / polymer mixed solution. This is a method in which several tens of composite ultra-thin films obtained by self-diffusion are dropped on a water surface via a tank wall to form a film.

However, the characteristics of the composite film of a functional low-molecular compound such as a liquid crystal dye and a polymer prepared in this manner are not always satisfactory.

(Means for Solving the Problems) The problem of the prior art as described above is that a liquid crystal is formed in pores of a porous polymer film formed by evaporating a solvent from a polymer solution containing water and alcohol. The problem is solved by a polymer composite film formed by filling a substance such as a dye, and a fixed film including electrodes provided with the polymer composite film interposed therebetween.

The dispersed phase in the present invention is obtained by uniformly dispersing a liquid crystal or a dye alone or a mixture of a liquid crystal and a dye in a polymer matrix, and is different from the heterogeneous dispersion obtained by a conventionally known casting method.

The polymer composite film used according to the present invention is produced, for example, by the following method. In this method, a porous polymer film is obtained by evaporating the solvent from a polymer solution containing water and alcohol, and the porous polymer film is filled with functional low molecules such as liquid crystals and dyes to form a composite. A membrane is obtained, electrodes are provided via the composite membrane, and a fixed membrane is obtained.

(Effect) Ethyl alcohol and water form a cyclic cluster of three molecules due to hydrogen bonding between ethyl alcohol molecules, and these three clusters are further associated with each other to incorporate one hydronium ion. A compound is formed, and this inclusion compound is hydrogen-bonded to a water molecule. For this reason, alcohol water in a solution in which a certain amount of alcohol water is dispersed in a solution in which a polymer is dissolved in a good solvent becomes uniform spherical particles due to interfacial tension as the solvent evaporates, and the solvent evaporates. Form. Thereafter, it was found that a porous membrane having spherical pores in which alcoholic water was completely evaporated was obtained by drying and drying at 100 ° C. or higher. Also, since ethyl alcohol has hydrophilicity,
A porous membrane can also be obtained when a certain amount of alcohol is uniformly diffused in a solution in which a polymer is dissolved in a good solvent, and then the solvent is evaporated in a humid environment. If the polymer composite film of the present invention is formed at a temperature slightly higher than room temperature during film formation, the dispersed phase of each other is connected by thin channels due to shrinkage during film formation.

 Further, the present invention will be described in detail.

In the present invention, (1) after dissolving a polymer in a good solvent, adding a certain amount of alcohol and water, mixing well, casting the mixture on a flat petri dish, and obtaining a solvent-evaporated porous membrane ( 2) In method (1), after adding a certain amount of alcohol and mixing well, the mixture is cast on a flat petri dish,
The solvent is evaporated in a container whose humidity has been adjusted in advance (such as a digitizer or a chromatographic developing tank) to obtain a porous film. After the porous film obtained as described above is filled with liquid crystal (and / or dye) in a reduced pressure drier, a sample can be prepared by attaching electrodes.

As the polymer that can be used in the present invention, any polymer can be used as long as it can form a liquid crystal (and / or dye) / polymer fixed film. As the polymer, polyethylene, polyacrylic acid, polymethyl acrylate, polyvinyl acetate, polyacrylonitrile, polyvinyl chloride, polyvinyl fluoride such as polyvinyl fluoride and addition polymer of vinyl compound, polymethacrylic acid, polymethyl methacrylate, poly Methacrylic esters such as ethyl methacrylate, polyvinylidene chloride, polyvinylidene fluoride, vinylidene cyanide, vinylidene fluoride / trifluoroethylene copolymer, vinylidene fluoride / tetrafluoroethylene copolymer, vinylidene cyanide / vinyl acetate copolymer Copolymers of vinyl compound or fluorine compound such as coalescence, compounds containing fluorine such as polytrifluoroethylene, polytetrafluoroethylene, polyhexafluoropropylene, polyamides such as nylon 6, nylon 66, polyimide, poly Urethane, polypeptides, polyethylene terephthalate polyester, polycarbonate, polyoxymethylene, polyethylene oxide, polypropylene oxide, and the like polyethers. As the polymer, a commercially available polymer can be used alone, but it can also be used as a mixed system in which various polymers are combined. In this case, the polymers are compatible with each other, and not only have excellent film forming properties but also use various properties of the obtained fixed film, such as chemical stability, weather resistance, impact resistance (thermal and mechanical). It is desirable to use them in combination in consideration of the purpose.

A good solvent is good for dissolving the polymer, and differs depending on the polymer. For example, polyvinyl chloride is tetrahydrofuran, cyclohexanone, methyl ethyl ketone, dimethylformamide, etc., polyvinyl acetate is chloroform, methanol, acetone, butyl acetate, etc., polyacrylate, polymethacrylate is acetone,
Ethyl acetate, tetrahydrofuran, toluene, etc., polyacrylonitrile, dimethylformamide, etc., polyethylene oxide, benzene, dimethylformamide, etc .; And cyclic ethers such as ethylene oxide, propylene oxide, tetrahydrofuran and dioxane, amines such as n-butylamine, and amides such as dimethylformamide and dimethylacetamide. The amount of the solvent to be added may be arbitrarily determined based on the amount of the polymer, but is preferably a 20-0.5% solution in view of film forming properties.

As the liquid crystal that can be used in the present invention, any liquid crystal that can form a liquid crystal / polymer fixed film can be used. For example, p-azoxyanisole, cholesteryl nonanoate, 4-methoxybenzylidene-4'-n-
Butylaniline, 4-methoxy-4'-butylazoxy-benzene, 4,4'-dimethoxyazobenzene, p-
Nematic liquid crystals such as azoxyanisole, 4-cyano-4'-n-pentylbiphenyl, p-2methoxybutyl-p'-dianobiphenyl, terephthal-bis-butylaniline, N- (4-cyanobenzylidene) -4 ' -N-
Octyloxyaniline, dodecyloxyazobenzene, ethyl p- (p-phenylbenzalamino) benzoate, 4-heptyloxybenzylidene-4'-bentylaniline, 4-butyloxybenzal-4-ethylaniline, 4- ( 4'-phenylbenzylideneamino) -n
-Butylcinnamate, 4- (4'-decyloxybenzylideneamino) 2-methylbutylcinnamate, 4-
(N-hexyloxy) phenyloxy-4 ″-(2-
Methylbutyl) biphenyl-4'-carboxylate,
Smectic liquid crystal such as ZLI-3489, cholesterol nonanoate,
Discotic liquid crystals such as (-)-2-methyl-p- (p'-methoxybenzylideneamino) cinnamic acid, cholesteryl myristate, cholesterol halides and esters, and cholesteric liquid crystals such as hexabutoxytriphenylene. In this case, the above liquid crystal can be used alone, but a plurality of liquid crystals can be mixed and used for the purpose of improving the performance of the base liquid crystal such as a phase transition temperature, a temperature range, a chemical stability and a film forming property.

Dyes (pigment-containing) which can be used in the present invention include non-linear dyes such as azo, anthraquinone, tetrazine and coumarin dichroic dyes which are conventionally mixed with liquid crystal and used for the light absorption anisotropy of the dye. 4- {methylamine-4'-nitrostilbene, o- (mp-) nitroaniline, 2-methyl-4-nitroaniline, merocyanine, etc. having optical properties, and bis (1-thio-2-phenolate)
Nickel-tetrabutylammonium, bis (1-thio-2-naphtholate) nickel-tetrabutylammonium, bis (1,2,3,4-tetrachloro-5,6-dithiophenolate) nickel (II) tetra-n And near-infrared absorbing dyes such as -butylammonium.

As the alcohol used in the present invention, lower monohydric alcohols such as methanol and ethanol are preferable. The amount of the alcohol to be added may be any amount, but is preferably 5 to 30% with respect to the common solvent within a range where the polymer does not precipitate. Further, auxiliary additives such as hydrocarbons such as benzene, toluene and xylene can be added to the alcohol, if desired.

The water used in the present invention is preferably pure water. In the above, the amount of water to be added to the alcohol may be any amount as long as the polymer does not precipitate, but is preferably 5 to 50% based on the alcohol. Alternatively, after uniformly diffusing a certain amount of alcohol in a solution of a polymer dissolved in a good solvent, and then evaporating the solvent in a humid environment to obtain a porous polymer film, the relative humidity of the environment is Although it depends on the type of the solvent, it is 60-100%, preferably 75-95%.

In the porous polymer film obtained by the present invention, the diameter and distribution of pores of the formed porous film are uniform because alcohol water is uniformly present as fine droplets in the polymer solution until film formation. It is. Further, since the dispersed phase is formed by alcohol, the mechanical strength and dimensional stability are greatly improved without being hindered from film formation. Such features are important in using the present porous fixed membrane as an industrial material.

EXAMPLES Next, the present invention will be described in more detail with reference to examples.

Example 1. Vinylidene fluoride-trifluoroethylene copolymer 7.
After 5 parts were dissolved in 100 parts of tetrahydrofuran solvent, 10 parts of ethyl alcohol and 3 parts of pure water were added, mixed well, cast on a flat petri dish, and formed into a film by a solvent evaporation method. A heat treatment was performed at 6 ° C. for 6 hours to obtain a cast film having a pore diameter of about 8 μm, the pores of which were connected by thin channels to form a continuous phase. This film was impregnated and filled with 2.5 parts of liquid crystal and ZLI-3489 in a vacuum dryer at 90 ° C. to obtain a fixed film. FIG. 1 shows a DE hysteresis curve of the sample of the fixed film obtained. For comparison, the results of a vinylidene fluoride-trifluoroethylene copolymer and a liquid crystal (ZLI-3489) are shown in FIGS. 2 and 3, respectively, and 7.5 parts of a vinylidene fluoride-trifluoroethylene copolymer and ZLI- FIG. 4 shows the results of a composite membrane prepared by dissolving 2.5 parts of 3489 in 100 parts of a common solvent, tetrahydrofuran and casting the same by the above-mentioned ordinary method. Fig. 1, 2
As can be seen from FIG. 3 and FIG. 3, the hysteresis curve of the immobilized film on which ZLI-3489 is immobilized does not become a typical rectangular hysteresis curve such as vinylidene fluoride-trifluoroethylene copolymer, liquid crystal, and ZLI-3489. However, it is clear that polarization inversion has occurred. When the amplitude of the electric field is about 4 MV / m, the vinylidene fluoride-trifluoroethylene copolymer shows only a nearly linear behavior.
The hysteresis curve of the fixed film is caused by the polarization reversal of ZLI-3489, and is because ZLI-3489 exhibits ferroelectricity. That is, the vinylidene fluoride-trifluoroethylene copolymer is a ZLI-3489 fixed film. On the other hand, the composite film obtained by the conventional method shows almost linear behavior when the amplitude of the electric field is about 4 MV / m, so that the ZLI-3489 fixing effect is not so recognized.

Example 2. Vinylidene fluoride-tetrafluoroethylene copolymer [vinylidene fluoride 80%, manufactured by Daikin Industries, Ltd.] 7.5
The resulting solution was dissolved in 100 parts of a tetrahydrofuran solvent, mixed with 10 parts of ethyl alcohol, and then cast on a flat petri dish to evaporate the solvent in a chromatographic developing tank adjusted to a relative humidity of 80% to form a film. Then, in a vacuum oven at 100 ° C,
Heat treatment was performed for 8 hours to obtain a cast film. From the SEM image of this film, it was found that the obtained film was a porous film having a pore size of 4-5 μm. The porous film is treated with a liquid crystal, 4- [4'-ndecyloxybenzylideneamino] at 100 ° C. in a vacuum oven.
After impregnating and filling with 2.5 parts of 2-methylbutyl cinnamate (DOBAMBC), an electrode was attached to obtain a test sample. The DE hysteresis curve of the specimen was obtained and compared with that of the vinylidene fluoride-tetrafluoroethylene copolymer and DOBAMBC used as starting materials. Impregnated with vinylidene fluoride-tetrafluoroethylene copolymer porous membrane DOBAMBC,
The hysteresis curve of the filled liquid crystal fixing film shows the same hysteresis curve as in Example 1, and it can be seen that the polarization inversion has occurred. On the other hand, for comparison, a hysteresis curve of a composite membrane obtained by casting a DOBAMBC and vinylidene fluoride-tetrafluoroethylene copolymer by a common method using tetrahydrofuran as a common solvent shows a nearly linear behavior,
The fixed effect of DOBAMBC is not very noticeable.

Example 3 A mixture of 7 parts of polyvinylidene fluoride (produced by Kureha Chemical Industry Co., Ltd.) and 3 parts of methyl methacrylate was dissolved in 100 parts of methyl ethyl ketone solvent, and 20 parts of methyl alcohol and 3 parts of pure water were added. It was cast on a petri dish and the solvent was slowly evaporated to obtain a cast film. From the SEM image of the film, it was found that the obtained film was a porous film having a pore size of about 5 μm, and the pores were connected by narrow channels to form a continuous phase.
This film was impregnated and filled with liquid crystal ZLI-3489 (manufactured by Merck) at 80 ° C. in a vacuum dryer to obtain a composite film. Repeat this composite membrane for 12
When heated to 0 ° C, ZLI-3489 oozed out on the film surface. This is because ZLI-3489 exudes continuous voids formed by a matrix composed of polyvinylidene fluoride and methyl methacrylate as a continuous phase domain, and is in good agreement with the result of the SEM image. This development is ZLI-3
It is found at a transition temperature of 489 from the cholesteric to isotropic phase of 87 ° C or higher.

Example 4. In Example 1, instead of the liquid crystal, ZLI-3489, 0.5 g of o-nitroaniline was dissolved in 0.5 cc of ethyl alcohol to obtain a ZLI.
Except for using a mixture mixed with -3489 2.0 g, the same treatment as in Example 1 was performed to obtain a composite film in which a liquid crystal / dye mixture was dispersed in a polymer as fine spheres. The obtained composite film shows a hysteresis curve, and polarization inversion has occurred. In other words, the polymer is a liquid crystal / dye fixing film. For comparison, a composite film obtained by a conventional method using ZLI-3489 and o-nitroaniline with methyl ethyl ketone as a common solvent did not show a remarkable hysteresis curve like a porous film impregnated with a liquid crystal / dye mixture. .

As described in detail above, the fixed film obtained by the present invention exhibits polarization inversion characteristics.

[Brief description of the drawings]

FIG. 1 shows the D of the immobilized membrane of the present invention obtained in Example 1.
It is a figure showing an -E hysteresis curve. FIG. 2 is a diagram showing a DE hysteresis curve of a vinylidene fluoride-trifluoroethylene copolymer used in Example 1 as a starting material of a fixed film of the present invention. FIG. 3 is a view showing a DE hysteresis curve of a liquid crystal, ZLI-3489, used as a starting material of the fixed film of the present invention in Example 1. FIG. 4 is a view showing a DE hysteresis curve of the composite film obtained by a conventional method in Example 1.

Continuation of the front page (56) References JP-A-62-28712 (JP, A) JP-T-58-501631 (JP, A) WO 87/1822 (WO, A1)

Claims (5)

(57) [Claims] 1. A polymer composite film formed by filling a substance into pores of a porous polymer film formed by evaporating a solvent from a polymer solution containing water and alcohol, and the polymer composite film A fixed film comprising electrodes provided on both sides of the fixed film. 2. The fixed membrane according to claim 1, wherein said substance is a dispersed phase continuous in a molecule. 3. The fixed film according to claim 1, wherein said substance is a liquid crystal. 4. The fixed membrane according to claim 1, wherein said substance is a dye. 5. The fixed film according to claim 1, wherein said substance is a mixture of liquid crystal and dye.