JP2001108829A - Method of manufacturing liquid crystalline polymer- water dispersion, liquid crystalline polymer-water dispersion, method of manufacturing optical device, and optical device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of economically manufacturing an optical device and an optical device by attaining a safe and simplified process without rubbing. SOLUTION: The method for manufacturing a liquid crystalline polymer-water dispersion is characterized by subjecting a monomer with a liquid crystalline group or the monomer with the liquid crystalline group and another monomer to emulsion polymerization so as to form a core part, subjecting a monomer with a photo reactive group or the monomer with the photo reactive group and another monomer to emulsion polymerization so as to form a shell part surrounding the core part and obtaining a core-shell structure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a liquid crystalline polymer aqueous dispersion, a liquid crystalline polymer aqueous dispersion, a method for producing an optical element using the liquid crystalline polymer aqueous dispersion, and an optical element. More specifically, the present invention relates to an optical element for color compensation or viewing angle compensation of a liquid crystal display.

[0002]

2. Description of the Related Art In recent years, the use of multimedia in personal computers has progressed, and color display has become common in laptop personal computers. In laptop computers, STN liquid crystal displays and TFT liquid crystal displays are mainly used.

The STN liquid crystal display is a display element utilizing a birefringence mode, and therefore has a serious problem that it is colored by a phase difference generated in the liquid crystal and cannot display in black and white. In order to solve such a problem, D-ST
An N-type (a method using a compensating liquid crystal cell) was attempted, but this method goes against the demand of the era of thin and light, which is a characteristic of the liquid crystal display, and is high in manufacturing the compensating liquid crystal cell. The yield is poor in terms of productivity, which requires accuracy, and there are many problems in using it.

As a method for solving these problems of the liquid crystal display and the compensating liquid crystal cell, for example, Japanese Patent Application Laid-Open No.
No. 149624 discloses F- using a stretched resin film.
The STN method has been proposed, and Japanese Patent Application Laid-Open Nos. 3-87720 and 4-330319 disclose a method for maintaining the compensation performance of the D-STN method and reducing its weight and thickness.
A method of performing color compensation using a film in which a liquid crystalline polymer is twisted has been proposed. The retardation compensator of this liquid crystal display is composed of a light-transmitting substrate, an alignment film formed on the substrate, and a liquid crystal polymer layer fixed on the alignment film in a twisted alignment state. .

Further, recently, as disclosed in Japanese Patent Application Laid-Open No. 7-191217, a discotic liquid crystal film is disposed on the upper and lower surfaces of a liquid crystal cell to compensate for the viewing angle of a TFT liquid crystal display. Attempts have been made to improve the viewing angle characteristics of the cell. This compensating plate for a TN type liquid crystal display is disclosed in Japanese Patent Application Laid-Open No. 3-87720.
And a light-transmitting substrate, as in the case of the phase difference compensating plate of the liquid crystal display described in
It is composed of an alignment film formed on the substrate and a liquid crystalline polymer layer formed on the alignment film.

As described above, in recent years, in STN liquid crystal displays and TFT liquid crystal displays, there has been a demand for an optical film having a higher compensation performance than in the past, and liquid crystal polymers have been studied as a solution to this problem. Are coming.

Conventionally, an alignment film is used in an optical element using a liquid crystalline polymer in order to bring the liquid crystalline polymer into a specific uniform alignment state. This alignment film is formed as a polyimide film by applying a thin film of an organic solvent solution of a precursor of polyimide on a substrate, drying and heating and heating to a temperature of a hundred and several tens of degrees, and rubbing this. In this way, the orientation direction in the plane of the alignment film is controlled, and at the same time, a tilt angle, which is a rise from the plane, is generated. When such an alignment film is formed on a resin film substrate, the resin film must not be dissolved or deteriorated in an organic solvent for the alignment film, and must have a heat resistance sufficient to withstand the heating and firing temperature required for forming the alignment film. Sex is required.
In addition, when an organic solvent is used, measures must be taken to keep the process below the explosion limit, and the equipment and the like become large.

In rubbing, dust comes out from the rubbing roll cloth, and thus, if a dirt on the alignment film such as fibers and small pieces of the alignment film is removed, a suction device and a cleaning step are required. Furthermore, since the insulator film surface is rubbed, static electricity is easily generated, so that an ionizer static electricity removing device must be provided, and a device for preventing electrostatic destruction must be provided around the substrate. Furthermore, since the rubbing roll controls the pressing strength based on the distance, it must be constantly adjusted according to the roll cloth that is being worn away, and the cloth must be replaced after processing a predetermined number of substrates. Must.

[0009]

Various techniques have been proposed as techniques which do not require such alignment by a rubbing roll. Among them, photo-alignment techniques such as crosslinking, dimerization, isomerization, and decomposition by light irradiation have attracted attention.
However, a compensation film made of discotic liquid crystal has been developed, and the viewing angle has been improved with one film, so that the expectation of the optical alignment technology has been reduced from the viewpoint of capital investment and the like. However, discotic liquid crystals are expensive and have problems in the manufacturing method.

On the other hand, with the enlargement of the area, the increase in the definition, and the diversification of display modes, there is a limit on rubbing. It has become. However,
The conventional method of photo-alignment has a structure in which an alignment film and a liquid crystal layer are overlaid, which is not only complicated in manufacturing, lowers the yield and increases the cost, but also reduces the actual performance. The characteristics for compensating the upper liquid crystal display could not be sufficiently exhibited.

Accordingly, the present invention has been made in order to solve the above-mentioned problems, and an object of the present invention is to secure and simplify the process without relying on rubbing. To provide a method and an optical element for manufacturing an optical element more economically.

[0012]

The present invention comprises the following constitutions.

(1) In a method for producing a liquid crystalline polymer aqueous dispersion, a monomer having a liquid crystalline component is polymerized or an organic liquid crystalline polymer obtained by polymerizing the monomer and another monomer is used. A method for producing an aqueous liquid crystalline polymer dispersion, comprising dispersing a solvent solution in water and removing an organic solvent later.

(2) The method for producing an aqueous liquid crystalline polymer dispersion according to (1), wherein the aqueous liquid crystalline polymer dispersion contains a photoreactive polymer.

(3) A liquid crystalline polymer aqueous dispersion is prepared in a photoreactive polymer aqueous solution (2).
3. The method for producing a liquid crystalline polymer aqueous dispersion according to 1.).

(4) The photoreactive polymer is a polymer of a monomer having a photodimerization reaction component or a copolymer of a monomer having a photodimerization reaction component and another monomer. The method for producing a liquid crystalline polymer aqueous dispersion according to (2) or (3), which is characterized in that:

(5) In the method for producing a liquid crystalline polymer aqueous dispersion, a monomer having a liquid crystalline component is emulsion-polymerized, or a monomer having a liquid crystalline component and another monomer are emulsion-polymerized. A method for producing an aqueous liquid crystalline polymer dispersion, comprising:

(6) The method for producing an aqueous liquid crystalline polymer dispersion according to (5), wherein the aqueous liquid crystalline polymer dispersion contains a photoreactive polymer.

(7) The liquid crystalline polymer aqueous dispersion is prepared in a photoreactive polymer aqueous solution (6).
3. The method for producing a liquid crystalline polymer aqueous dispersion according to 1.).

(8) In the method for producing a liquid crystalline polymer aqueous dispersion, a monomer having a liquid crystal component is emulsion-polymerized,
Or, a monomer having a liquid crystal component and another monomer are emulsion-polymerized, and using this as a core, a monomer having a photoreactive component around it is emulsion-polymerized, or a monomer having a photoreactive component. A method for producing a liquid crystalline polymer aqueous dispersion, comprising forming a shell by subjecting a monomer to emulsion polymerization to form a core / shell structure.

(9) The photoreactive polymer is a polymer of a monomer having a photodimerization reaction component or a copolymer of a monomer having a photodimerization reaction component and another monomer. The method for producing a liquid crystalline polymer aqueous dispersion according to any one of (6) to (8), which is characterized in that:

(10) Production of the aqueous liquid crystalline polymer dispersion according to any one of (5) to (9), wherein the aqueous liquid crystalline polymer dispersion is prepared by soap-free emulsion polymerization. Method.

(11) Any one of (1) to (10)
Item 10. An aqueous liquid crystalline polymer dispersion prepared by the method described in Item 9.

(12) The aqueous liquid crystalline polymer dispersion according to (11) is coated on a support, dried and heated, while applying an electric field or a magnetic field and / or irradiating with polarized ultraviolet light, and then at room temperature. A method for producing an optical element, comprising:

(13) An optical element formed by the method described in (12).

Hereinafter, the present invention will be described in detail.

The liquid crystalline polymer according to the present invention is a homopolymer of a monomer having a liquid crystal component or a copolymer with another monomer, more specifically, an ethylenically unsaturated monomer having a liquid crystal component. Or a copolymer with another ethylenically unsaturated monomer.

Examples of the monomer having a liquid crystal component according to the present invention will be shown below, but the invention is not limited thereto.

[0029]

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[0030]

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[0031]

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Other ethylenically unsaturated monomers used in the liquid crystalline polymer according to the present invention include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, amyl acrylate, hexyl acrylate, Acrylic esters such as cyclohexyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate and benzyl acrylate; methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, amyl methacrylate, methacryl Hexyl acid, cyclohexyl methacrylate, methacrylic acid 2
-Methacrylates such as ethylhexyl, benzyl methacrylate, benzyl methacrylate and glycidyl methacrylate; olefins or diolefins such as ethylene, propylene, butadiene and isoprene; vinyl ethers such as vinyl methyl ether and vinyl ethyl ether; vinyl acetate , Vinyl propionate, vinyl pivalate, etc .; vinyl ketones, such as methyl vinyl ketone, ethyl vinyl ketone, propyl vinyl ketone; styrenes, such as styrene, vinyl toluene, α-methyl styrene; acrylamide, N-methyl acrylamide , N-ethylacrylamide, N-propylacrylamide, butylacrylamide, N, N-dimethylacrylamide, N, N-diethylacrylamide, N-
Morpholinoacrylamide, N-benzylacrylamide, methacrylamide, N-methylmethacrylamide,
N-methylacrylamide, N-propylmethacrylamide, butylmethacrylamide, N, N-dimethylmethacrylamide, N, N-diethylmethacrylamide, N
Acrylamides such as morpholinomethacrylamide and N-benzylmethacrylamide; vinyl halides such as vinyl chloride, vinylidene chloride and chloroprene; and olefins. Here, normal (n), iso (i), secondary (s), and tertiary (t) are omitted, but any monomer can be used.

The amount of the ethylenically unsaturated monomer having a liquid crystal component of the present invention must be 30% by weight or more, preferably 40% by weight in the polymer.

For the purpose of improving the dispersion stability of the liquid crystalline polymer, an ethylenically unsaturated monomer having an anionic functional group of not more than 10% by weight, preferably not more than 5% by weight based on the total weight of monomers. A monomer may be used. Specifically, examples of the monomer when the anionic functional group is a carboxyl group include acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, 2-oxycarbonylethyl acrylate, and 2-oxycarbonyl Ethyl methacrylate, 2-
(2'-oxycarbonylethylcarboxy) ethyl acrylate, 2- (2'-oxycarbonylethylcarboxy) ethyl methacrylate, 2- (m-oxycarbonylbenzoyloxy) ethyl acrylate, 2-oxycarbonylethylcarboxyethylene, m- Examples include, but are not limited to, oxycarbonylbenzoyloxyethylene, 4-oxycarbonylstyrene, and the like. In the present invention, among the above monomer units, acrylic acid, methacrylic acid, maleic acid and itaconic acid are preferably used. Examples of the monomer whose anionic functional group is a sulfonic acid group include styrene sulfonic acid, acryloyloxymethyl sulfonic acid, acryloyloxyethyl sulfonic acid, acryloyloxypropyl sulfonic acid, and 2-acrylamido-2-methylpropane. Sulfonic acid and the like can be mentioned. These acids may be salts of alkali metals (eg, Na, K, etc.) or ammonium ions.

The aqueous liquid crystalline polymer dispersion of the present invention is prepared by subjecting a liquid crystalline polymer solution obtained by solution polymerization of a monomer having a liquid crystalline component in an organic solvent together with another monomer to an aqueous liquid. Dispersion, the method of removing the organic solvent later, after dissolving the separately polymerized liquid crystalline polymer in the organic solvent, the method of dispersing in an aqueous solution in the same manner as described above, a monomer having a liquid crystalline component,
Alternatively, it is prepared by a method of emulsion polymerization in an aqueous solution together with other monomers.

The method for obtaining the aqueous liquid crystalline polymer dispersion will be described more specifically.

As a method for preparing an aqueous dispersion using a solution of a liquid crystalline polymer in an organic solvent, a solution of a liquid crystalline polymer in a low boiling point organic solvent and an aqueous solution containing a surfactant as a dispersion stabilizer and / or A method of mixing with an aqueous solution containing a water-soluble polymer, and then emulsifying and dispersing using a disperser such as a high-speed rotary mixer, a colloid mill, or an ultrasonic disperser can be used. The water-soluble polymer is 100 ° C water at 20 ° C.
The water-soluble polymer dissolves in an amount of 0.5 g or more, or does not precipitate at 20 ° C. after heat dissolution, and preferably dissolves in an amount of 1 g or more.

The low-boiling organic solvent is a water-insoluble organic solvent having a boiling point of 30 to 180 ° C., preferably 45 to about 160 ° C. at normal pressure, and specific examples thereof include ethyl acetate, butyl acetate and propion. Examples thereof include ethyl acid, methyl ethyl ketone, cyclohexane, 2-ethoxyethyl acetate, and chloroform.

As the surfactant as a dispersion stabilizer of the aqueous liquid crystalline polymer dispersion of the present invention, a general surfactant can be used, and an anionic surfactant, a nonionic surfactant, a cationic surfactant, Both surfactants and amphoteric surfactants can be used. As surfactants, as anionic surfactants, as soaps, sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, sodium lauryl sulfate, sodium dioctylsulfosuccinate, sodium triisopropylnaphthalenesulfonate, etc., as nonionic surfactants , Polyoxyethylene nonyl phenyl ether, polyoxyethylene stearate, polyoxyethylene sorbitan monolaurate, polyoxyethylene-polyoxypropylene block copolymer, etc., as a cationic surfactant,
Cetylpyridinium hydrochloride, trimethylammonium hydroxide and the like, and amphoteric surfactants include dimethylamylbetaine, ethylglycine and the like.

As the water-soluble polymer as a dispersion stabilizer of the aqueous liquid crystalline polymer dispersion of the present invention, any of a water-soluble natural compound, a semi-synthetic water-soluble polymer or a synthetic water-soluble polymer can be used. Its salts, guar gum, pullulan, glycogen, gum arabic, albumin, agar,
Proteins such as starch derivatives, gelatin, albumin, casein, etc., gelatin derivatives, graft polymers of gelatin with ethylenically unsaturated monomers, cellulose derivatives such as hydroxyethylcellulose, carboxymethylcellulose, cellulose sulfate, dextrin, dextran, dextran Water-soluble natural compounds such as sugar derivatives such as sulfates and semi-synthetic water-soluble polymers, polyacrylic acid, polymethacrylic acid and salts thereof, polyvinyl alcohol,
Synthetic aqueous solution such as homopolymer of polyvinyl alcohol partial acetal, poly-N-vinylpyrrolidone, polyacrylamide, poly-N-vinylimidazole, polyvinylpyrazole, etc. or copolymer of these monomers and other monomers Functional polymers.

According to the present invention, the liquid crystalline polymer composition of the present invention is used to irradiate a photoreactive polymer with light to perform photoalignment, thereby providing a liquid crystal display having excellent performance for color compensation and viewing angle compensation. An optical element is characterized in that a liquid crystalline polymer and a photoreactive polymer are present adjacent to each other. Therefore,
When a water-soluble polymer is used as a dispersion stabilizer for a liquid crystalline polymer aqueous dispersion, the use of a water-soluble photoreactive polymer as a dispersion stabilizer improves liquid crystallinity rather than using the above-mentioned water-soluble polymer. This is preferable because a photoreactive polymer can be arranged adjacent to the molecule.

The photoreactive polymer used in the present invention is one which undergoes photodimerization, photobonding or photodecomposition. Any photoreactive polymer having a photoreactive group can be used without limitation. A polymer having such a photoreactive group, a photoreactive polymer having a repeating unit, or a polymer derived from a monomer having a photoreactive group is preferably used.

As the photoreactive group,

[0044]

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And the like. Here, R is a hydrogen atom, an alkyl group, an aryl group, a cyano group, a nitro group, or the like.

Further, as a repeating unit of the following photoreactive polymer,

[0047]

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And the like.

Further, the following monomers having a photoreactive group include:

[0050]

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And the like.

The photoreactive group, the repeating unit of the photoreactive polymer, and the monomer having a photoreactive group are not limited to these, but include cinnamoyl group, chalcone group and coumarin group. Those having a photoreactive group are preferred.

In the present invention, the photoreactive polymer may be a photoreactive polymer derived from a photoreactive monomer or a photoreactive polymer copolymerized with another monomer. There may be.

Other monomers copolymerized with the photoreactive monomer include other ethylenically unsaturated monomers used in the liquid crystalline polymer (omitted here) and the anionic functional group. Monomers described in the examples of monomers in the case of a carboxyl group (omitted here), and N-vinylpyrrolidone, N-vinylimidazole, N-vinylpyrazole, acrylamide, N-vinylcarbazole,
N-vinylpyrrolidine, N-vinyltriazole, N-
Vinyloxazoline, N-vinylisothiazoline, N-
Vinyl piperazine, N- (2-acryloyloxyethyl) pyrrolidone, N-acryloylmorpholine and the like can be mentioned. Among these, as a water-soluble monomer, N
-Vinylpyrrolidone, N-vinylimidazole, N-vinylpyrazole, N- (2-acryloyloxyethyl) pyrrolidone, N-acryloylmorpholine are preferred. In the present invention, among the water-soluble photoreactive polymers,
A monomer having an aprotic group or a water-soluble photoreactive polymer is preferable to a monomer having an aprotic group or a polymer having an aionic group or a protic group. Also, among the above water-soluble polymers, copolymer water-soluble polymers of aprotic monomers are preferable.

The photoreactive polymers useful in the present invention are exemplified below, but are not limited thereto.

[0056]

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[0057]

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Here, n represents a polymer. Further, n ₁ and n ₂ are the ratios of the repeating units in the copolymer.

In the present invention, the water-soluble photoreactive polymer is used not only for preparing a liquid crystalline aqueous dispersion by dispersing an organic solvent solution of a liquid crystalline polymer in water, but also for emulsifying the liquid crystalline polymer. It can also be preferably used as a dispersion stabilizer for a polymer. In this case, emulsion polymerization may be performed in an aqueous solution of a water-soluble photoreactive polymer, or an aqueous solution of a water-soluble reactive polymer may be added after the emulsion polymerization.

Another aqueous liquid crystalline polymer dispersion of the present invention is prepared by emulsion polymerization, and a further aqueous liquid crystalline polymer dispersion of the present invention is obtained by emulsion polymerizing a liquid crystalline polymer to form a core. A so-called emulsion polymer having a core / shell structure (hereinafter sometimes referred to as a latex), which is subjected to emulsion polymerization using a photoreactive polymer as a shell.

As the polymerization method of the polymer used in the present invention, various polymerization methods such as organic solvent solution polymerization, suspension polymerization, bulk polymerization and emulsion polymerization can be used. For all three, the obtained polymer is used as an aqueous dispersion of a liquid crystalline polymer from an organic solvent solution, and emulsion polymerization can be used as it is as an aqueous dispersion of a liquid crystalline polymer. As the polymerization method, a usual emulsion polymerization method can be applied, and the polymerization can be performed by referring to Takatsu Otsu and Masayoshi Ohshita, "Experimental Method for Polymer Synthesis", Kagaku Dojin, 1996, printing. Usually, polymerization is performed by adding a polymerization initiator to a solution, and in the case of emulsion polymerization, further adding a dispersion stabilizer (emulsifier) as necessary, and in a reaction vessel filled with nitrogen gas,
The monomer is dropped, and the polymerization is carried out while suppressing the heat of polymerization from outside. After completion of the polymerization, the obtained polymer is precipitated in a non-solvent or taken out by precipitation. In the case of emulsion polymerization, the polymer is often used as it is. Although the polymerization temperature may be 100 ° C. or higher, it is usually 30 to 100 ° C. and about -10 to 60 ° C. in the case of a redox polymerization initiator. In the case of emulsion polymerization, the polymerization reaction is carried out in water or water, or in some cases, water containing an organic solvent miscible with water (eg, methanol, ethanol, acetone, etc.). When an organic solvent miscible with water is used, the amount of the organic solvent is 0 to 30% by volume relative to water, preferably 0 to 15%.
%. The emulsion polymerization reaction is carried out using 0.05 to 5% by weight of a radical polymerization initiator and, if necessary, 0.1 to 10% by weight of an emulsifier based on the monomer to be polymerized.
As the polymerization initiator, potassium persulfate, ammonium persulfate, t-butyl peroctoate, benzoyl peroxide, isopropyl percarbonate, 2,4-dichlorobenzoyl peroxide, methyl ethyl ketone peroxide, cumene hydroperoxide, dicumyl peroxide , Azobisisobutyronitrile,
2,2'-azobis (2-amidinopropane) hydrochloride and the like, and as a redox polymerization initiator, hydrogen peroxide-ferrous chloride, potassium persulfate-sodium acid sulfite, cumene hydroperoxide-ferrous sulfate,
Benzoyl peroxide-diethylaniline and the like can be mentioned. Dispersion stabilizer (hereinafter sometimes referred to as emulsifier)
Examples include anionic, amphoteric and nonionic surfactants, as well as water-soluble polymers. For example, sodium laurate, sodium dodecyl sulfate, sodium 1-octoxycarbonylmethyl-1-octoxycarbonylmethanesulfonate, sodium laurylnaphthalenesulfonate, sodium dodecylbenzenesulfate, sodium laurylbenzenesulfonate, sodium laurylphosphate,
Examples thereof include polyoxyethylene nonylphenyl ether, polyoxyethylene sorbitan lauryl ester, polyvinyl alcohol, and an emulsifier and a water-soluble polymer described in JP-B-53-6190. In emulsion polymerization, depending on the purpose, the polymerization initiator, concentration, polymerization temperature,
It goes without saying that the reaction time and the like can be changed widely and easily.

In the aqueous liquid crystalline polymer dispersion of the present invention, an emulsion polymer having a core / shell structure by an emulsion polymerization method is used as one of useful methods. Core of the present invention /
A liquid crystalline polymer aqueous dispersion having a shell structure is composed of a liquid crystalline polymer as a core and a liquid crystalline polymer having a double structure of a photoreactive polymer as a shell and a photoreactive polymer adjacent to each other in a particle. It is a functional one, and the emulsion polymer of the liquid crystalline polymer of the core is further emulsion-polymerized while dropping the photoreactive monomer forming the shell or other monomers together with the monomer. Can be easily obtained. There is also a method of batch-introducing the monomers forming the shell, but it is preferable to add the monomers dropwise while avoiding heat generation accompanying polymerization.

The emulsion polymer having a core / shell structure is
By emulsion polymerization in the presence of the above polymerization initiator and emulsifier,
After forming the core emulsion polymerization particles, when polymerizing the monomer forming the shell, an emulsifier may be further added, or the polymerization may be performed without the emulsifier. Although the additional addition of an emulsifier is often necessary for the stability of the resulting latex, if an excess emulsifier is present, particles composed only of the polymer that forms a shell other than the intended one may be produced as a by-product. Therefore, it is preferable that the amount of the emulsifier additionally added after the formation of the core latex be suppressed to about 0.001 to 2% by weight based on the core latex particles, or not added at all. In order to complete the core / shell structure, it is important that polymerization of the core latex at the time of addition of the shell-forming monomer is completed as much as possible, and the polymerization rate of the core polymer is 90% or more, preferably 95%. % Or more, particularly preferably substantially 100%. In addition, the weight ratio of the core / shell polymer is preferably 70/30 to 99.000 in order for the polymer forming the shell to achieve the purpose of the photoreaction.
5 / 0.5, preferably 90/10 to 99.5 / 0.5
In the range.

The aqueous liquid crystalline polymer dispersion of the present invention may contain a surfactant or a water-soluble polymer which may hinder the alignment of the liquid crystalline component. Polymerization method) is preferred. Soap-free emulsion polymerization is a method in which a surfactant is not used as a dispersion stabilizer, and emulsion polymerization is performed using a hydrophilic portion of a polymerization initiator. For soap-free emulsion polymerization,
There are many reports such as JP-B-49-5615, JP-B-1-36484 and JP-A-4-19242. In the present invention, a liquid crystalline polymer dispersion is prepared by an emulsion polymerization method using these known techniques. Can be obtained.

The optical element of the present invention can be obtained by applying the aqueous liquid crystalline polymer dispersion of the present invention to a support.

The support used in the present invention has a light transmittance of 80.
% Or more, and a cellulose ester film such as a cellulose triacetate film,
Optically isotropic materials such as a cellulose acetate propionate film, a cellulose acetate butyrate film, a polycarbonate film, a polyarylate film, a polyether sulfone, and a polyester film are preferably used, and a uniaxially stretched polyester may also be used.

The support used in the present invention may be provided with an undercoat layer as used for a silver halide photographic light-sensitive material. Examples of the undercoat layer include a gelatin layer, a vinyl acetate-maleic anhydride copolymer layer, and a polyvinyl alcohol layer. The surface of the support may be subjected to saponification treatment, corona discharge treatment, plasma discharge treatment in gas, plasma treatment, glow discharge treatment, flame treatment, ultraviolet treatment, etc. These processes may be performed.

The optical element of the present invention is provided vertically above and below a liquid crystal cell and is used as an optical element for color compensation or viewing angle compensation of a liquid crystal display, and is mainly composed of a liquid crystalline polymer composition layer and a support. It is configured.

In producing the optical element of the present invention, examples of a method of applying the liquid crystalline polymer composition include a wire bar, a knife coater, a comma coater, and a lip coater. Absent. In the present invention, a coating method may be appropriately selected and used.

In the process of applying the liquid crystalline polymer composition of the present invention to a support to produce the optical element of the present invention, the drying temperature is a temperature at which liquid crystallinity is not exhibited, that is, less than 70 ° C. It is better to do it.

The optical element of the present invention may exhibit liquid crystallinity after being wound once through the above-mentioned coating and drying step, or may exhibit liquid crystallinity during or after the coating and drying step. Good. By heating the liquid crystalline component in the layer to a temperature higher than the temperature at which liquid crystallinity can be expressed, the material having liquid crystalline properties can undergo molecular motion in the coating film, and by applying an electric or magnetic field and by irradiating polarized light, It can be oriented in a predetermined direction.

The temperature at which the liquid crystalline polymer used in the present invention can exhibit liquid crystallinity is in the range of 70 to 130 ° C., and during this state, an electric or magnetic field is applied, or polarized ultraviolet light is applied to the liquid crystal polymer. The polymer can be oriented. When only a liquid crystalline polymer and no photoreactive polymer are present, the liquid crystalline polymer is oriented only by applying an electric or magnetic field. When a photoreactive polymer is contained adjacently, the liquid crystalline polymer can be oriented by irradiating polarized ultraviolet rays, but can be similarly oriented by applying an electric or magnetic field. . Further, both application of an electric or magnetic field and irradiation of polarized ultraviolet light may be provided. If the temperature is lower than 70 ° C., the orientation state of the oriented liquid crystalline polymer is unstable depending on the use environment of the liquid crystal display,
This state cannot be maintained, and the compensation performance may be invalidated.

As described above, the photoreactive polymer to be used in the present invention is, as described above, a double bond such as a cinnamic acid group, a chalcone group or a coumarin group due to photodimerization between photoreactive polymers facing each other. Cross-linking (cyclozeation) is caused. At that time, the direction can be recorded by polarized light, and this contributes to the orientation of the liquid crystalline polymer, specifically, the liquid crystalline component. This is called optical alignment. Regarding optical alignment, the technology has already been studied in the field of liquid crystal devices, and Masaki Hasegawa, “Liquid Crystal”,
A review is provided in Vol. 3, No. 1, pages 3 to 16 (1999).

When a liquid crystal compound such as a conventional compensation film is oriented, the liquid crystal compound and the alignment layer are stacked as separate layers. However, in the optical element of the present invention, the liquid crystal polymer layer The present inventors believe that the presence of such a layer in the same layer makes the orientation of the liquid crystalline component very easy and improves the efficiency. .

In the present invention, examples of the ultraviolet light source for photo-alignment and for photodimerizing the photoreactive polymer include an ultra-high pressure mercury lamp, a medium pressure mercury lamp, a xenon lamp, a halogen lamp, a fluorescent lamp and the like. And a combination of a light source and a polarizer (through a polarizer) to irradiate linearly polarized light. As a polarizer, a stretch-dyeed PVA is mainly used.

In the present invention, as a technique for performing alignment other than polarized ultraviolet rays, the above-described electric field or magnetic field may be applied to align the liquid crystalline component. By heating the liquid crystalline component in the layer to a temperature equal to or higher than the liquid crystal manifestation temperature, the liquid crystalline component can undergo molecular motion in the layer, and is oriented in a predetermined direction by polarized ultraviolet irradiation or by application of an electric or magnetic field. Will be. After the orientation by irradiation or application, by cooling the layer of the liquid crystalline polymer composition to a temperature lower than the liquid crystal manifestation temperature, the liquid crystalline orientation is fixed in a desired direction to obtain an optical element. I can do it. In this case, the application condition of the electric field or the magnetic field cannot be univocally determined because it depends on the intended optical function and the type of the liquid crystalline polymer material. In any case, in the present invention, the liquid crystalline polymer is oriented in a predetermined direction in a coating state by a photochemical reaction of the photoreactive polymer by irradiation with polarized ultraviolet rays, in particular, by a photodimerization reaction and / or by application of an electric field and a magnetic field. Oriented.

[0077]

EXAMPLES The present invention will be described below with reference to examples, but is not limited thereto.

[Evaluation] [Evaluation of Light Transmittance] A sample was placed between two polarizing plates arranged so that the light transmission axis was perpendicular. The installation direction of the sample is the direction of the polarization axis irradiated with polarized ultraviolet light during sample preparation,
Alternatively, the polarizing plates were arranged so that either axis was parallel to the direction of the magnetic field line of the magnetic field or the rubbing direction, and were closely attached, and the light transmittance was measured.

[Evaluation of Operation Method] The degree of difficulty and the complexity of the operation for producing an optical element are indicated by △, Δ and ×.

[Preparation of Aqueous Liquid Crystalline Polymer Dispersion] Preparation Example 1 [Polymerization of Liquid Crystalline Polymer PL-1] 200 g of LC-1, 2 g of azobisisobutyronitrile and tetrahydrofuran were placed in a 5000 ml three-necked flask. 1800 ml was added and mixed, and nitrogen was bubbled for 30 minutes. The polymerization reaction was carried out for 5 hours while heating to 50 ° C. and stirring. After cooling to room temperature, the reaction solvent was distilled off under reduced pressure using a rotary evaporator, and the reaction mixture was concentrated. A precipitate was precipitated from this mixed solution in diethyl ether, and the solid content was dried under vacuum to obtain a liquid crystalline polymer PL-1. The yield was 72%. This PL-1
Was dissolved in a small amount of THF, cast into a film on a slide, dried under vacuum, heat-treated at 110 ° C. for 10 minutes, and cooled to room temperature. When the two polarizing plates were placed in a crossed Nicols state, and a cast film-prepared preparation was placed between them, it was confirmed that the film had optical anisotropy. When this film was further heated and observed at 123 ° C. in the same manner, the film was not isotropic optically and was isotropic.

[Polymerization of Photoreactive Polymer P (VCi-VP)] In a 5000 ml brown three-necked flask, 30 g of vinylcinnamate, 70 g of vinylpyrrolidone, 1 g of azobisisobutyronitrile, and 1900 of tetrahydrofuran
ml was added and mixed, and nitrogen was bubbled for 30 minutes. 5
The temperature was raised to 0 ° C., and the polymerization reaction was performed for 3 hours while stirring. After cooling to room temperature, the reaction solvent was distilled off under reduced pressure using a rotary evaporator, and the reaction mixture was concentrated. This mixture was added to diethyl ether to precipitate a precipitate, which was dried under vacuum, and poly (vinylcinnamate-co-vinylpyrrolidone) [P
(VCi-VP)]. From the elemental analysis, the polymerization composition ratio was vinyl cinnamate unit: vinyl pyrrolidone unit = 33: 67 by weight ratio, and the yield was 65%.

[Preparation of Liquid Crystalline Polymeric Aqueous Dispersion PD-1] 100 g of PL-1 and 100 g of ethyl acetate as a low boiling point solvent were mixed and mixed with a dissolver for 1 hour. 400 g of an aqueous solution containing 8 g of sodium triisopropylnaphthalate and 2% by weight of P (VCi-VP) was mixed with this mixture at 50 ° C., and ethyl acetate was decompressed while emulsifying and dispersing with a homogenizer equipped with an explosion arrester. Distilled 8
After heating to 0 ° C., the dispersion operation was stopped, and the mixture was allowed to cool to room temperature to obtain a liquid crystalline polymer aqueous dispersion PD-1 having an average particle size of 80 nm.

Preparation Example 2 [Polymerization of liquid crystalline polymer PL-2 and preparation of liquid crystalline polymer aqueous dispersion PD-2] Distilled water was placed in a 1000 ml three-necked flask equipped with a stirrer, a thermometer, and a reflux condenser. 360m
and 5 g of sodium dodecyl sulfate were added, and the mixture was heated and stirred at 75 ° C. under a nitrogen stream. 1% by weight of LC-1
Was added immediately after adding a solution of 10 ml of water containing ammonium persulfate, and the mixture was immediately heated and stirred for 20 minutes. Then 90 g of LC-1 and 1 of LC-1
The mixture was heated and stirred while 30 ml of an aqueous solution containing ammonium persulfate in a weight% was dropped by a constant-speed dropping device over 2 hours. After completion of the dropwise addition, the mixture was further heated and stirred for 3 hours to complete the polymerization reaction. Then, it is allowed to cool to room temperature,
A liquid crystalline polymer (latex) PL-2 having a thickness of 0 nm was obtained, and this was designated as a liquid crystalline polymer aqueous dispersion PD-2.

Preparation Example 3 [Preparation of aqueous liquid crystalline polymer dispersion PD-3] 50 g of PL-2 was taken, 0.8 g of P (VCi-VP) was dissolved therein, and the mixture was thoroughly stirred. Thus, a liquid crystalline aqueous dispersion PD-3 was prepared.

Preparation Example 4 [Polymerization of Liquid Crystalline Polymer PL-3 and Preparation of Liquid Crystalline Polymer Aqueous Dispersion PD-4]
50 ml of distilled water polyvinyl, 4 g of pyrrolidone and 1
g of sodium dodecyl sulfate were mixed and dissolved, and the mixture was heated and stirred at 75 ° C. under a nitrogen stream. In addition, LC-1
10 ml of an aqueous solution containing 1% by weight of ammonium persulfate
, 10 g of LC-1 was added immediately, and the mixture was heated and stirred for 20 minutes. Next, 85 g of LC-1 and 30 ml of a 1% by weight aqueous solution of ammonium persulfate of LC-1 were added.
The mixture was heated and stirred while dripping over two hours from different constant-speed dropping devices. After the addition, the mixture was further stirred for 2 hours. Then, a mixed solution of 2.5 g of vinyl cinnamate and 2.5 g of ethyl acrylate, and 0.05 g (5% by weight based on the total weight of vinyl cinnamate and ethyl acrylate) were added. 10 ml of an aqueous solution containing ammonium persulfate was dropped from each of the constant-rate dropping devices over 0.5 hours. After the completion of the dropwise addition, the mixture was heated and stirred for another 2 hours to complete the polymerization reaction. Thereafter, the mixture was allowed to cool to room temperature and filtered to obtain a liquid crystalline polymer (latex) PL-3 having a core / shell structure having an average particle size of 122 nm, which was designated as a liquid crystalline polymer aqueous dispersion PD-4.

Preparation Example 5 [Polymerization of Liquid Crystalline Polymer PL-4 and Preparation of Liquid Crystalline Polymer Aqueous Dispersion PD-5] In an apparatus similar to PL-2, distilled water 3 was added.
60 ml, 8 g of poly (vinylcinnamate-co-vinylpyrrolidone) (weight ratio 3: 7) and 1 g of sodium dodecyl sulfate were added, and the mixture was heated and stirred at 75 ° C. under a nitrogen stream. To this, ammonium persulfate was added at 1% by weight of LC-1.
Immediately after addition of a solution of 10 ml of water containing
g was added and heated and stirred for 20 minutes. Then, 90 g of LC-1 and 30 ml of an aqueous solution of ammonium persulfate containing 1% by weight of LC-1 were added to each of two different constant-rate dropping devices.
The mixture was heated and stirred while being dropped over time. After the completion of the dropwise addition, the mixture was further heated and stirred for 3 hours to complete the polymerization reaction. Thereafter, the mixture was allowed to cool to room temperature to obtain a liquid crystal polymer (latex) PL-4 having an average particle size of 130 nm. This was designated as liquid crystalline polymer aqueous dispersion PD-5.

Preparation Example 6 [Polymerization of Liquid Crystalline Polymer PL-5 and Preparation of Liquid Crystalline Polymer Aqueous Dispersion PD-6] Using the same apparatus as in PL-2, 360 ml of distilled water was added at 75 ° C. under a nitrogen stream. And heated and stirred. To this, 10 ml of an aqueous solution containing 0.1% by weight of ammonium persulfate of LC-1 was added, and immediately 10 g of LC-1 was added.
Was added and heated and stirred for 20 minutes. Then 0.21g
20 ml of an aqueous solution containing ammonium (0.25% by weight of LC-1 to be added later) was added, and the mixture was heated and stirred while dropping 85 g of LC-1 over 1.5 hours with a constant-rate dropping device. Furthermore, 0.013 g (0.2% of the total weight of vinyl cinnamate and ethyl acrylate added later)
10 ml of an aqueous solution containing 5% by weight of ammonium persulfate
Was added. Thereafter, a mixed solution of 2.5 g of vinyl cinnamate and 2.5 g of ethyl acrylate was added to the mixture at a constant speed by a dropping device.
It was added dropwise over 5 hours. After the completion of the dropwise addition, the mixture was heated and stirred for 2 hours to complete the polymerization reaction. Then let it cool down to room temperature,
Liquid crystalline polymer (latex) PL with an average particle size of 115 nm
-5 was obtained. This was designated as a liquid crystalline polymer aqueous dispersion PD-6.

Example 1 A 60 μm-thick cellulose triacetate film coated with a gelatin thin film (0.1 μm) (manufactured by Konica Corporation)
After applying PD-1 on a wire bar and drying at 50 ° C., the temperature is raised to 110 ° C., and an electromagnet is used so that the magnetic force lines extend in a direction at an angle of 45 ° to the plane direction. A magnetic field with an intensity of 10 kG (Gauss) was applied. After aligning the liquid crystalline polymer, it is allowed to cool to room temperature and has a thickness of 2.0 μm.
m optically anisotropic layers were formed.

Example 2 Example 2 was repeated except that PD-1 was changed to PD-2.

Example 3 A 60 μm thick cellulose triacetate film coated with a gelatin thin film (0.1 μm) (manufactured by Konica Corporation)
PD-3 was applied on top using a wire bar. 50 ℃
After heating at 110 ° C. for 10 minutes, the film was irradiated with linear polarized light through an ultra-high pressure mercury lamp through a visible light cut filter, and further through a polarizer for 5 minutes from the coating film side, and then cooled to room temperature. An optically anisotropic layer having a thickness of 0.0 μm was formed.

Example 4 Example 4 was repeated except that PD-3 was changed to PL-4.

Example 5 The same procedure as in Example 3 was carried out except that PD-3 was changed to PD-5.

Example 6 The procedure of Example 3 was repeated, except that PD-3 was changed to PD-6.

Example 7 Example 7 was repeated except that PD-3 was changed to PD-1.

Comparative Example 1 A 60 μm thick cellulose triacetate film coated with a gelatin thin film (0.1 μm) (manufactured by Konica Corporation)
An aqueous solution of polyvinyl alcohol (a saponification value of about 80%) was applied on the substrate, dried with hot air at 80 ° C., and then subjected to a rubbing treatment to form an alignment film. At this time, rubbing was performed while applying ionic wind to suck and remove rubbed debris and dust on the cloth of the rubbing roll, and further to prevent generation of static electricity.

A coating solution obtained by dissolving 1.6 g of PL-1 and 0.05 g of cellulose acetate butyrate (CAB531-1, manufactured by Eastman Chemical Company) in 6.6 g of methyl ethyl ketone was placed on this alignment film. Was applied with a wire bar. Next, the mixture was heated in a thermostat at 110 ° C. for 3 minutes to orient the liquid crystalline polymer compound, and then allowed to cool to room temperature to form an optically anisotropic layer having a thickness of 2.0 μm.

Comparative Example 2 A 60 μm thick cellulose triacetate film coated with a gelatin thin film (0.1 μm) (manufactured by Konica Corporation)
A coating solution obtained by dissolving 1.6 g of PL-1 and 0.05 g of cellulose acetate butyrate (CAB531-1, manufactured by Eastman Chemical Co., Ltd.) in 6.6 g of methyl ethyl ketone was applied on a wire bar. And 50 ℃
And dried. While heating this at 110 ° C for 10 minutes,
From a high pressure mercury lamp through a visible light cut filter,
After irradiation for 5 minutes from the coating film side through a polarizer, the film was cooled to room temperature to form an optically anisotropic layer having a thickness of 2.0 μm.

The results evaluated above are shown below.

[0099]

[Table 1]

(Results) When the samples of Examples 1 to 7 and Comparative Example 1 were placed between orthogonal Nicols, it was recognized that all of the samples had a uniform homogeneous orientation. However, Comparative Example 2 was bright under crossed Nicols, but its light transmittance did not show angle dependence, and it was recognized that it was in a random parallel orientation. Were not formed, and no difference in transmittance was observed in any direction. The liquid crystalline water-based polymer of the present invention was found to have the same properties as those obtained by rubbing with an organic solvent solution as in Comparative Example 1, but it was difficult to take measures against cumbersome and dusty rubbing. In addition, it can be handled without concern such as explosion of handling organic solvents.

[0101]

The present invention is an optical element having no alignment film, does not require rubbing, does not require any equipment considerations for dust, and has a uniform liquid crystal alignment by an electromagnetic field or light. In addition to simplification of the number of process passes, the use of water-based coating enables simplification of the process equipment and safety, and therefore a significant reduction in production costs. An element can be obtained.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme court ゛ (Reference) C09K 19/38 C09K 19/38 4J100 G02F 1/13363 G02F 1/13363 (72) Inventor Sota Kawakami Hino, Tokyo 1 Sakuracho, Konica Corporation Konica Stock Company In-house F-term (reference) 2H049 BA06 BA42 BB44 BB49 BC01 BC05 BC06 BC09 BC22 2H091 FA08X FA08Z FA11Z FB02 FC23 LA19 LA20 4H027 BA13 BD12 BD21 BD24 4J011 KA29 PA69 PC02 PC06 QA01 QA01 QA01 QA01 AA47 AA48 AA59 AC36 BA05 BA06 BA10 BA12 BA24 BA25 BA27 BA32 BA34 DA04 DB04 EA06 FA07 GA02 GA06 4J100 AA02Q AA03Q AB02Q AB03Q AB04Q AB07R AC03Q AC04Q AE03Q AE04Q AF01Q AJ02R AJ08R AJ09RQ08 BA16R BA56R BC04Q BC43P BC43Q BC54Q BC79Q CA04 CA05 CA29 FA20 GD 02 JA39

Claims (13)

[Claims] In a method for producing a liquid crystalline polymer aqueous dispersion, an organic solvent of a liquid crystalline polymer obtained by polymerizing a monomer having a liquid crystalline component or polymerizing the monomer and another monomer. A method for producing a liquid crystalline polymer aqueous dispersion, comprising dispersing a solution in water and removing an organic solvent later. 2. The method for producing an aqueous liquid crystalline polymer dispersion according to claim 1, wherein the aqueous liquid crystalline polymer dispersion contains a photoreactive polymer. 3. The method for producing an aqueous liquid crystalline polymer dispersion according to claim 2, wherein the aqueous liquid crystalline polymer dispersion is prepared in a photoreactive polymer aqueous solution. 4. The photoreactive polymer is a polymer of a monomer having a photodimerization reaction component or a copolymer of a monomer having a photodimerization reaction component and another monomer. The method for producing a liquid crystalline polymer aqueous dispersion according to claim 2 or 3, wherein: 5. A method for producing a liquid crystalline polymer aqueous dispersion, comprising emulsion-polymerizing a monomer having a liquid-crystalline component or emulsion-polymerizing a monomer having a liquid-crystalline component and another monomer. A method for producing a liquid crystalline polymer aqueous dispersion, comprising: 6. The method for producing an aqueous liquid crystalline polymer dispersion according to claim 5, wherein the aqueous liquid crystalline polymer dispersion contains a photoreactive polymer. 7. The method for producing an aqueous liquid crystalline polymer dispersion according to claim 6, wherein the aqueous liquid crystalline polymer dispersion is prepared in an aqueous photoreactive polymer solution. 8. A method for producing a liquid crystalline polymer aqueous dispersion, wherein a monomer having a liquid crystal component is emulsion-polymerized, or a monomer having a liquid crystal component and another monomer are emulsion-polymerized. As a core, a monomer having a photoreactive component around the core is emulsion-polymerized, or a monomer having a photoreactive component and another monomer are emulsion-polymerized to form a shell to form a core / shell structure. A method for producing a liquid crystalline polymer aqueous dispersion, comprising: 9. The photoreactive polymer is a polymer of a monomer having a photodimerization reaction component or a copolymer of a monomer having a photodimerization reaction component and another monomer. The method for producing a liquid crystalline polymer aqueous dispersion according to any one of claims 6 to 8, wherein: 10. The liquid crystalline polymer aqueous dispersion is prepared by soap-free emulsion polymerization.
The method for producing a liquid crystalline polymer aqueous dispersion according to any one of the above. 11. A liquid crystalline polymer aqueous dispersion prepared by the method according to claim 1. Description: 12. The liquid crystalline polymer aqueous dispersion according to claim 11, which is applied on a support, dried and heated, while applying an electric field or a magnetic field and / or irradiating polarized ultraviolet light.
A method for producing an optical element, comprising cooling to room temperature later. 13. An optical element formed by the method according to claim 12.