JP3355680B2 - Acrylate compounds and liquid crystal devices using them - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acrylate compound and a liquid crystal device manufactured using the acrylate compound. More specifically, the present invention relates to a liquid crystal-encapsulated thin film that does not use a polarizing plate, that is, one that can electrically control the blocking and transmission of a visual field, and is particularly used for a screen for blocking a visual field such as a building window or a show window. Further, by displaying characters and graphics, and by electrically switching the display with high-speed response, decorative display boards and clocks such as advertising boards, display devices of calculators, display devices that require a bright screen, for example, The present invention relates to a liquid crystal device used as a display device of a computer terminal or a display device of a projection.

[0002]

2. Description of the Related Art Conventionally, a liquid crystal device has a TN (twisted nematic) type using a nematic liquid crystal,
An STN (super twisted nematic) type is in practical use. Further, a device using a ferroelectric liquid crystal has been proposed.

[0003] These methods have a problem that there is a limit in making a screen brighter because a polarizing plate is required, and there is a problem that the yield at the time of producing a display device is reduced because an alignment treatment is required.

On the other hand, as a method of manufacturing a bright and high-contrast liquid crystal device without requiring a polarizing plate or an alignment treatment, a method of dispersing liquid crystal droplets in a polymer and forming the polymer into a film is known.

However, in a liquid crystal device in which liquid crystal droplets are dispersed in a polymer, sufficient transparency can be obtained in addition to the trouble of optimizing the matching and mismatch between the individual refractive indexes of the liquid crystal material and the polymer. Requires a high voltage of 25 V or more, and does not have a low drive voltage characteristic which is regarded as important in practical use of a display device.

Japanese Patent Application Laid-Open Publication No. HEI 1 ( 1999) discloses a technology that enables low-voltage drivability, high contrast, and time-division drivability, which are important characteristics required for practical use of this liquid crystal display device.
Japanese Patent Application No. 198725 discloses a liquid crystal device having a structure in which a transparent solid substance is distributed in a three-dimensional network in a continuous layer of a liquid crystal material. As a means for forming a three-dimensional network-like transparent solid substance in the continuous layer of the liquid crystal material, a liquid crystal material and an ultraviolet-curable polymer-forming monomer or oligomer, a polymerization initiator and the like are added to a solution containing an ultraviolet ray. At the same time to polymerize the monomer or oligomer to obtain a transparent solid substance.

[0007]

However, in the above-mentioned liquid crystal device, although a low-voltage drivability is achieved, a hysteresis phenomenon in which the transmittance at the time of increasing the voltage and the transmittance at the time of decreasing the voltage show different values in the electro-optical characteristics. This lowers the margin of time-division driving, and is extremely problematic in performing gradation display.

The problem to be solved by the present invention is to provide a liquid crystal device which makes it possible to reduce the difference in transmittance between the rise and fall of the voltage in the electro-optical characteristics, that is, the hysteresis width, thereby enabling high-quality gradation display. To provide.

[0009]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have intensively studied a polymerizable composition for forming a transparent solid substance, and have found that a liquid crystal device having a small hysteresis width can be manufactured. It has arrived.

That is, in order to solve the above-mentioned problems, the present invention includes two substrates having at least one transparent electrode layer and a dimming layer supported between these substrates,
In the liquid crystal device, wherein the light modulating layer is composed of a transparent solid substance and a liquid crystal material, the transparent solid substance is represented by a general formula (1)

[0011]

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(Wherein, R represents an alkyl or alkoxy group having 1 to 20 carbon atoms, X represents a single bond or-
CH ₂ CH ₂ —, Y represents a hydrogen atom or a methyl group, a represents 0 or 1, and when a = 0, b represents 0
And b represents an integer of 1 to 10 when a = 1. )

A liquid crystal device characterized by polymerizing a polymerizable composition containing a monofunctional acrylate compound represented by the formula:

The liquid crystal device of the present invention can be manufactured, for example, according to the following method. That is, a polymerizable composition containing a monofunctional acrylate compound represented by the general formula (1), a liquid crystal material, and, if necessary, between two substrates having at least one electrode layer having transparency. By interposing a polymerization initiator, a chain transfer agent, a photosensitizer, and a light modulating layer constituent material containing a dye crosslinking agent, and by irradiating ultraviolet rays through a transparent substrate, by polymerizing the polymerizable composition, A liquid crystal device having a light control layer made of a transparent solid substance and a liquid crystal material can be manufactured.

Further, the compound represented by the general formula (1) of the present invention can be produced according to the following production method. That is,

[0016]

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(Wherein, R represents an alkyl or alkoxy group having 1 to 20 carbon atoms, X represents a single bond or-
CH ₂ CH ₂ —, Y represents a hydrogen atom or a methyl group, a represents 0 or 1, and when a = 1, b represents an integer of 1 to 10. )

The compound represented by the general formula (2) is reacted with acrylic acid chloride or methacrylic acid chloride in a solvent using a base such as triethylamine, or acrylic acid using a condensing agent such as dicyclohexylcarbodiimide. Alternatively, the compound represented by the general formula (1) can be produced by reacting with methacrylic acid.

The substrate used in the present invention may be a rigid material, for example, glass, metal, or the like, or a flexible material, for example, a plastic film. Then, two substrates are opposed to each other and are obtained at an appropriate interval.

Further, at least one of them has transparency, but does not necessarily require complete transparency. If the liquid crystal device is used to act on light passing from one side of the device to the other, both substrates are provided with the appropriate transparency.

On this substrate, an appropriate transparent or opaque electrode may be arranged over the entire surface or partially according to the purpose. Note that a spacer for maintaining a space can be interposed between the two substrates, similarly to a well-known liquid crystal device.

When the liquid crystal device of the present invention is used for a display device of a computer terminal or a display device of a projection, it is preferable to provide an active element on the electrode layer.

The transparent solid substance in the light modulating layer may be a substance dispersed in fibrous or particulate form, or a film-shaped substance in which liquid crystal material is dispersed in small droplets. Are more preferable.

The liquid crystal material preferably forms a continuous layer, and is indispensable for forming a disordered state of the liquid crystal material to form an optical interface and to scatter light.

If the average diameter of the liquid crystal droplets or the average diameter of the shape of the transparent solid substance in the liquid crystal device of the present invention is too large or too small compared to the wavelength of light, the light scattering property tends to decrease. , 0.2 to 2 μm is preferred.

The thickness of the light-scattering layer may be adjusted according to the purpose of use, in order to obtain a sufficient contrast between the opacity due to light scattering and the transparency achieved electrically, the distance between the substrates is set as follows: The range of 2 to 40 μm is preferred, and the range of 6 to 25 μm is particularly preferred.

It is a matter of course that the liquid crystal material used in the present invention does not need to be a single liquid crystal compound, and may be a mixture containing two or more liquid crystal compounds or a substance other than the liquid crystal compound. Any material which is generally recognized as a liquid crystal material in this technical field may be used, and a material having a positive dielectric anisotropy is preferable.

The liquid crystal used is preferably a nematic liquid crystal, a smectic liquid crystal, or a cholesteric liquid crystal, and particularly preferably a nematic liquid crystal. To improve its performance, cholesteric, chiral nematic liquid crystal,
A chiral smectic liquid crystal or the like or a chiral compound may be appropriately contained.

The liquid crystal material used in the present invention is preferably a compounded composition comprising at least one compound selected from the following compound group. The properties of the liquid crystal material, that is, the phase of the isotropic liquid and the liquid crystal To be appropriately selected, blended and used for the purpose of improving the transition temperature, melting point, viscosity, Δε (dielectric anisotropy), Δn (refractive index anisotropy), solubility with a transparent solid substance, and the like. Can be.

Examples of the liquid crystal material include 4-substituted benzoic acid 4′-substituted phenyl ester, 4-substituted cyclohexanecarboxylic acid 4′-substituted phenyl ester, 4-substituted cyclohexanecarboxylic acid 4′-substituted biphenyl ester, (4-substituted cyclohexanecarbonyloxy)
Benzoic acid 4'-substituted phenyl ester, 4- (4-substituted cyclohexyl) benzoic acid 4'-substituted phenyl ester, 4- (4-substituted cyclohexyl) benzoic acid 4'-substituted cyclohexyl ester, 4-substituted 4'-substituted Biphenyl, 4-substituted phenyl 4'-substituted cyclohexane, 4
-Substituted 4 "-substituted terphenyl, 4-substituted biphenyl 4'-substituted cyclohexane, 2- (4-substituted phenyl)
-5-substituted pyridine and the like can be mentioned. Particularly preferred among these compounds are compounds having a cyano group at least at one end of the molecule.

Examples of the polymer-forming monomer that forms the transparent solid substance include styrene, chlorostyrene,
α-methylstyrene, divinylbenzene; methyl, ethyl, propyl, butyl, amyl, 2-
Ethylhexyl, octyl, nonyl, dodecyl, hexadecyl, octadecyl, cyclohexyl, benzyl, methoxyethyl, butoxyethyl, phenoxyethyl, allyl, methallyl, glycidyl, 2-hydroxyethyl, 2-hydroxypropyl, 3-chloro-2-hydroxypropyl, Acrylate, methacrylate or fumarate having a group such as dimethylaminoethyl, diethylaminoethyl or the like; ethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, 1,3-butylene glycol, tetramethylene glycol, hexamethylene glycol, neopentyl glycol, Mono (meth) acrylates such as trimethylolpropane, glycerin and pentaerythritol or poly ( Data) acrylate; vinyl acetate,
Vinyl butyrate or vinyl benzoate, acrylonitrile,
Cetyl vinyl ether, limonene, cyclohexene, diallyl phthalate, diallyl isophthalate, 2-3,
-Or 4-vinylpyridine, acrylic acid, methacrylic acid, acrylamide, methacrylamide, N-hydroxymethylacrylamide or N-hydroxyethylmethacrylamide and their alkyl ether compounds; 2 mol or more of ethylene oxide per 1 mol of neopentyl glycol or Di (meth) acrylate of diol obtained by adding propylene oxide; di or tri (meth) acrylate of triol obtained by adding 3 moles or more of ethylene oxide or propylene oxide to 1 mole of trimethylolpropane; 1 mole of bisphenol A Di (meth) acrylate of a diol obtained by adding at least 2 mol of ethylene oxide or propylene oxide to 1 mol of 2-hydroxyethyl (meth) acrylate; Isocyanate or n-
Reaction product with 1 mol of butyl isocyanate; poly (meth) acrylate of dipentaerythritol, etc., such as trimethylolpropane triacrylate, tricyclodecane dimethylol diacrylate,
Particularly preferred are polyethylene glycol diacrylate, polypropylene glycol diacrylate, hexanediol diacrylate, neopentyl glycol diacrylate, and tris- (acryloxyethyl) isocyanurate.

Examples of the polymer-forming oligomer forming the transparent solid substance include caprolactone-modified hydroxypivalic acid ester neopentyl glycol diacrylate.

As a method for forming a light modulating layer containing a uniform transparent solid substance, for example, a uniform solution of a liquid crystal material, a polymer-forming monomer or oligomer, and, if necessary, a photopolymerization initiator is used. Alternatively, a uniform solution of a solvent, a polymer-forming monomer or oligomer, and, if necessary, a photopolymerization initiator is sandwiched between two substrates having electrode layers, or a spin coater is placed on one of the substrates. The coating may be performed using a coater, etc., and then the other substrate may be overlaid, which is irradiated with ultraviolet rays or thermally polymerized and cured.

The polymerization initiator that can be used in the present invention includes, for example, 2-hydroxy-2-methyl-1-
Phenylpropan-1-one (“Darocur 1173” manufactured by Merck), 1-hydroxycyclohexylphenylketone (“Irgacure 18” manufactured by Ciba-Geigy)
4 "), 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one (" Darocure 1116 "manufactured by Merck), benzyldimethyl ketal (" Irgacure 651 "manufactured by Ciba-Geigy), 2-
Methyl-1- [4- (methylthio) phenyl] -2-morpholinopropanone-1 (“Irgacure 907” manufactured by Ciba-Geigy), 2,4-diethylthioxanthone (“Kayacure DETX” manufactured by Nippon Kayaku Co., Ltd.) Ethyl p-dimethylaminobenzoate (Kayacure E manufactured by Nippon Kayaku Co., Ltd.
PA "), isopropylthioxanthone (" Kantacure ITX "manufactured by Ward Prekinsopp) and p
A mixture with ethyl dimethylaminobenzoate, and the like, but 2-hydroxy-2-methyl-1-
Phenylpropan-1-one is particularly preferred in terms of compatibility with liquid crystal materials, polymer-forming monomers or oligomers.

[0035]

The present invention will be described more specifically below with reference to examples of the present invention. However, the invention is not limited to these examples. In the following Examples and Comparative Examples, “%” represents “% by weight”. The symbols and contents used in the evaluation characteristics in each example are shown below.

(1) The light transmittance (T ₀ ) of the liquid crystal device when no voltage of V ₁₀ and V ₉₀ is applied is 0%
When the transmittance (T ₁₀₀ ) when the light transmittance does not change with the increase of the applied voltage is 100%, the applied voltage (V) at which the light transmittance becomes 90% is V ₉₀ , and the light transmission Rate 10
% And an applied voltage when made to V _10.

(2) When the hysteresis voltage is increased from 0 V, the light transmittance becomes 50%
The (T ₅₀₎ and comprising voltage and V _{5 0} ^UP, the light transmittance 100%
When a voltage at which the light transmittance becomes 50% when the voltage is lowered from a voltage sufficiently higher than (T ₁₀₀ ) is V ₅₀ ^DOWN , ΔV = V ₅₀ ^UP −V ₅₀ ^DOWN is an evaluation value of the hysteresis phenomenon. , And the hysteresis width.

Example 1 Synthesis of 4- (trans-4-n-butylcyclohexyl) phenyl acrylate

[0039]

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10.0 g of 4- (trans-4-n-butylcyclohexyl) phenol and 3.39 g of acrylic acid were dissolved in 80 ml of dichloromethane and stirred at room temperature. To this solution, 9.70 g of dicyclohexylcarbodiimide dissolved in 20 ml of dichloromethane was added dropwise over 10 minutes, and the mixture was reacted for 4 hours. After the reaction was completed, 200 ml of ethyl acetate was added, and the organic layer was washed with a dilute aqueous sodium hydrogen carbonate solution and then further with water. After drying the organic layer using anhydrous sodium sulfate, the solvent was distilled off to obtain 14.8 g of a crude product. The obtained crude product was purified using column chromatography (silica gel, ethyl acetate: n-hexane = 1: 10, Rf = 0.70),
Further recrystallization from methanol gave 4- (trans-
5.6 g (yield 45%) of 4-n-butylcyclohexyl) phenyl acrylate was obtained.

(Example 2) Liquid crystal compound

[0042]

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A liquid crystal composition (A) was prepared.

The physical properties of the liquid crystal composition (A) are shown in Table 1 below.

[0045]

[Table 1]

80% of the liquid crystal composition (A), 6% of 4- (trans-4-n-butylcyclohexyl) phenyl acrylate synthesized in Example 1 as a polymerizable composition, and caprolactone-modified hydroxypivalic acid ester neopentylglycol diester Acrylate (Nippon Kayaku Co., Ltd. “H
X-220 ") 13.6% and 2 as a polymerization initiator
-Hydroxy-2-methyl-1-phenylpropane-1
A light modulating layer forming material consisting of 0.4% -on was prepared.

This was sandwiched between two glass plates having an ITO electrode layer in which a small amount of a spacer having an average particle size of 11 μm was scattered on the electrode layer, and under a UV light (metal halide lamp, 80 W / cm ² ), Pass the glass sheet holding the forming material at a speed of 3.5 m / min, and 500 mJ / c
The polymerizable composition was polymerized by irradiating ultraviolet rays having energy corresponding to m ² to obtain a liquid crystal device.

When the light control layer of the obtained liquid crystal device was observed with an electron microscope, a transparent solid substance having a three-dimensional network structure was confirmed.

The characteristics of the obtained liquid crystal device are as follows: V ₁₀ =
1.54 V, V ₉₀ = 4.67 V, and ΔV = 0.06 V.

Example 3 The polymerizable composition of Example 2 was changed to 4- (trans-
4-n-butylcyclohexyl) phenyl acrylate 4% and "HX-220" (manufactured by Nippon Kayaku Co., Ltd.)
A liquid crystal device was obtained in the same manner as in Example 2 except that 15.6% was used.

When the light control layer of the obtained liquid crystal device was observed with an electron microscope, a transparent solid substance having a three-dimensional network structure was confirmed.

The characteristics of the obtained liquid crystal device are as follows: V ₁₀ =
5.42 V, V ₉₀ = 9.62 V, and ΔV = 0.35 V.

Example 4 In Example 2, 2% of 4- (trans-4-n-butylcyclohexyl) phenyl acrylate and "HX-22" were used as the polymerizable composition.
A liquid crystal device was obtained in the same manner as in Example 2 except that 17.6% of “0” (manufactured by Nippon Kayaku Co., Ltd.) was used.

Observation of the light control layer of the obtained liquid crystal device with an electron microscope confirmed a transparent solid substance having a three-dimensional network structure.

The characteristics of the obtained liquid crystal device are as follows: V ₁₀ =
8.19 V, V ₉₀ = 17.22 V, and ΔV = 0.97 V.

(Comparative Example 1) "LA" represented by the following formula as a polymerization composition in Example 2 (manufactured by Kyoeisha Yushi Kagaku Kogyo KK)

[0057]

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Then, a liquid crystal device was obtained in the same manner as in Example 2 except that 6% of “HX-220” (manufactured by Nippon Kayaku Co., Ltd.) was used.

When the light control layer of the obtained liquid crystal device was observed with an electron microscope, a transparent solid substance having a three-dimensional network structure was confirmed.

The characteristics of the obtained liquid crystal device are as follows: V ₁₀ =
4.51 V, V ₉₀ = 10.86 V, and ΔV = 0.48 V.

Comparative Example 2 In Example 2, "LA" (manufactured by Kyoeisha Yushi Kagaku Kogyo Co., Ltd.) was used as the polymerizable composition.
4% and "HX-220" (manufactured by Nippon Kayaku Co., Ltd.)
A liquid crystal device was obtained in the same manner as in Example 2 except that 15.6% was used.

When the light control layer of the obtained liquid crystal device was observed with an electron microscope, a transparent solid substance having a three-dimensional network structure was confirmed.

The characteristics of the obtained liquid crystal device are as follows: V ₁₀ =
5.41 V, V ₉₀ = 12.53 V, and ΔV = 0.64 V.

(Comparative Example 3) "LA" (manufactured by Kyoeisha Yushi Kagaku Kogyo Co., Ltd.) as the polymerizable composition in Example 2
2% and “HX-220” (manufactured by Nippon Kayaku Co., Ltd.)
A liquid crystal device was obtained in the same manner as in Example 2, except that 17.6% was used.

When the light control layer of the obtained liquid crystal device was observed with an electron microscope, a transparent solid substance having a three-dimensional network structure was confirmed.

The characteristics of the obtained liquid crystal device are as follows: V ₁₀ =
8.34 V, V ₉₀ = 20.32 V, ΔV = 1.15 V.

The results of the above Examples and Comparative Examples are shown in Table 2 below.

[0068]

[Table 2]

As is apparent from Table 2, the liquid crystal device according to the present invention has a small hysteresis width and a reduced driving voltage.

[0070]

The liquid crystal device according to the present invention is a light scattering type liquid crystal device having a small hysteresis width and capable of high-quality gradation display. Therefore, the liquid crystal device according to the present invention is extremely useful as a display device of a computer terminal, a display element of a projection, and the like.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C07C 69/54 C09K 19/30 CA (STN) CAOLD (STN) REGISTRY (STN)

Claims (2)

(57) [Claims] 1. General formula (1 ′) (Wherein, R represents an alkyl group or an alkoxy group having 1 to 20 carbon atoms, X represents a single bond or —CH ₂ CH ₂ —, Y represents a hydrogen atom or a methyl group, and a represents 0. , B represents an integer of 0 to 10.) 2. In the general formula (1 ′) according to claim 1,
An acrylate compound in which b = 0.