JPH07175051A - Liquid crystal/prepolymer composition and liquid crystal display element using the same - Google Patents

Abstract

PURPOSE:To produce a polymer dispersion type liquid crystal display element capable of being driven with a low voltage, having a precise threshold characteristic, low in hysteresis, having a high speed responsiveness and high in charge retention, and to produce a liquid crystal/prepolymer composition suitable to produce this liquid crystal display element. CONSTITUTION:In the liquid crystal/prepolymer composition incorporated with a prepolymer composition, a polymerization initiator and a liquid crystal and in which phase separation of the liquid crystal and a polymer is induced by polymerization, the prepolymer composition is mainly composed of a bifunctional acrylate having two double bond and an unifunctional acrylate having one double bond. And a HLB value of the unifunctional acrylate is 2.5 to 7.0, and the HLB value of the bifunctional acrylate is 3.5 to 11.0.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a liquid crystal display device, and more particularly to a polymer dispersion type liquid crystal display device having a liquid crystal dispersion film formed of a liquid crystal and a three-dimensional fine structure of polymer or the like. The present invention also relates to a liquid crystal / prepolymer composition suitable for producing a polymer dispersion type liquid crystal display device.

[0002]

2. Description of the Related Art One of the display methods in a liquid crystal display device is
There is a so-called polymer dispersion type liquid crystal display element in which a liquid crystal is dispersed in a droplet form by a support such as a resin or a liquid crystal dispersion film in which a resin network structure is formed is sandwiched between substrates with electrodes. In this method, in general, when no voltage is applied, the orientation of the liquid crystal is disturbed by the support,
Scatters light due to slight fluctuations in the refractive index. When a voltage is applied to this element, when the liquid crystal has a positive dielectric anisotropy, the liquid crystal molecules are aligned in the direction of the electric field and the fluctuation of the refractive index is reduced, so that the liquid crystal layer becomes transparent. When a dichroic dye is added to liquid crystal, the dye array is almost random and absorbs light when no voltage is applied, whereas when a voltage is applied, the dye is oriented perpendicular to the substrate and becomes transparent. . In any case, since this display method does not require a polarizing plate such as a twisted nematic mode, it has a feature that brighter display is possible without light loss (absorption) by the polarizing plate. There is. In addition, it has the advantage that the response speed is fast. Several methods have been reported as methods for forming such a dispersed structure. For example, a method of applying and drying an emulsion of an aqueous solution of a water-soluble polymer such as polyvinyl alcohol and liquid crystal (emulsion method), dissolving the soluble polymer and liquid crystal in a solvent to prepare a uniform solution, coating and drying the solution, and drying. Sometimes a polymer and liquid crystal are phase-separated (solvent evaporation method), a photopolymerizable substance such as an acrylic monomer, a liquid crystal and a photopolymerization initiator are enclosed in a space between upper and lower substrates, and ultraviolet rays are irradiated to the photopolymerizable substance. And a phase-separation method (photopolymerization method), a method in which a mixture of a thermopolymerizable substance-for example, an epoxy compound and its curing agent-and liquid crystal is sealed between the upper and lower substrates and then polymerized by heating to cause phase separation ( Thermal polymerization method) and the like. Among them, the photopolymerization method has been actively developed because of its controllable dispersion structure, good reproducibility, ease of film thickness control, and relatively easy application of conventional manufacturing processes. ing. However, the polymer-dispersed liquid crystal display device produced by such a photopolymerization method has the following problems. (1) The threshold characteristics are unclear and the operating voltage is high. (2) When the operating voltage is lowered, the response speed becomes slow, and low voltage driving and high speed responsiveness are not compatible. (3) Since the voltage-transmittance characteristic has a large hysteresis characteristic, it is difficult to display halftone. These are due to the lack of control of the distributed structure,
It is considered that this is due to the shape and size of the liquid crystal phase and its distribution. Further, (4) there is a problem that the charge retention rate is low, which makes it difficult to drive by an active element such as a thin film transistor.

[0003]

The present invention has been made in view of the above problems of the prior art, and an object of the present invention is to improve the above-mentioned drawbacks of a polymer dispersion type liquid crystal display device, enable low voltage driving, and clearly Provided are a polymer dispersion type liquid crystal display device having excellent threshold value characteristics, small hysteresis, fast response and high charge retention rate, and a liquid crystal / prepolymer composition suitable for producing the liquid crystal display device. To do.

[0004]

According to the present invention, a prepolymer composition comprising a radical-polymerizable monomer or a mixture of a radical-polymerizable monomer and a radical-polymerizable oligomer, a polymerization initiator and a liquid crystal are contained, and the phase separation of the liquid crystal and the polymer is achieved by the polymerization. In the induced liquid crystal / prepolymer composition, the prepolymer composition is mainly composed of a bifunctional acrylate having two double bonds and a monofunctional acrylate having one double bond. And a monofunctional acrylate HLB value of 2.5 or more and 7.0 or less, and a bifunctional acrylate HLB value of 3.5 or more and 11 or less, and Provided is a liquid crystal display device utilizing a phase-separated structure composed of a polymerization product of a composition. The liquid crystal / prepolymer composition of the present invention comprises a mixture of a radical-polymerizable monomer or a mixture of a radical-polymerizable monomer and a radical-polymerizable oligomer (hereinafter referred to as a prepolymer composition), a liquid crystal, and an external source such as heat or light. Generate radical species by energy,
It is basically composed of a polymerization initiator that induces radical polymerization in the monomer and / or oligomer. In the liquid crystal / prepolymer composition, the prepolymer composition has an increased molecular weight due to the induced polymerization reaction, and further the crosslinking reaction proceeds to cause phase separation of the liquid crystal from the initially uniform composition, resulting in a fine liquid crystal. It creates a dispersed structure in which the droplets are dispersed in the polymer. The size and shape of this dispersion structure and their distribution have a great influence on the electro-optical characteristics of the device, and therefore must be strictly controlled.
The liquid crystal / prepolymer composition of the present invention provides an extremely uniform dispersion structure, and a liquid crystal display device manufactured using the composition has features of low operating voltage, high response speed, and small hysteresis. ing. Such a remarkable effect is obtained by adding a double bond to the prepolymer composition.
And a monofunctional acrylate having one double bond, the monofunctional acrylate has an HLB value of 2.5 or more and 7.0 or less, and a bifunctional acrylate HLB. It can be expressed by setting the value to 3.5 or more and 11 or less. H
The LB value is generally used mainly to represent the polarity of the surfactant and can be calculated from the molecular structure. The larger the value, the higher the polarity. The HLB value includes a method for calculating Davis and a method for calculating Griffin. In the present invention, discussion will be made mainly with respect to HLB of Davis, but for compounds containing a group with no radix, the Griffin HLB can be substituted. Davis's HLB can be calculated by the following formula [JTDavi
es and EKRideal: “Interfacial Phenomena”, Aca
demic Press, New York (1961), p.366]. HLB = sigma (radix hydrophilic group) + sigma (radix lipophilic groups) +7 radix example -OH 1.9 -O- 1.3 -COO- 2.4 -CH- -0.475 -CH 2 - - _{0.475 -CH 3 -0.475 = CH- -0.475 (} CH 2 CH 2 O) 0.33 [CH (CH ₃₎ CH ₂ O] given as -0.15, from molecular structure It can be calculated. HLB value of monofunctional acrylate is 2.5 or more and 7.0
It must be: If it is larger than this range, the light scattering property when no voltage is applied is lowered, or the operating voltage is increased. Similarly, when it is small, the scattering property is lowered and the operating voltage is increased. In addition, the phenomenon that the initial scattering is lowered after the voltage is applied becomes remarkable. HLB
It is more preferable that the value is 3 or more and 6.5 or less.
Most preferably, it is 2 or more and 5.5 or less. The optimum HLB value varies slightly depending on the liquid crystal used, the liquid crystal concentration, and the composition ratio of the monofunctional acrylate and the bifunctional acrylate, but by adjusting the value within the above-mentioned preferred range, excellent characteristics can be exhibited. As the monofunctional acrylate having such an HLB value, various monofunctional acrylates can be used, but those having a low vapor pressure are preferable because they can be easily obtained and synthesized. When the vapor pressure is high, the acrylate is volatilized during the manufacturing process of the device or due to the change with time, and the composition is apt to change, which is not preferable. In order to reduce volatilization, it is preferable that the acrylate has a molecular weight of 200 or more and an ether bond is introduced into the structure. From such a viewpoint, the materials of the general formulas (1) and (2) can be exemplified as particularly preferable monoacrylates.

[0005]

Embedded image CH ₂ ═CH—COO— (R ₁ —O—) _m —C _n H _{2n + 1} (1) m is an integer of 0 to 6, R ₁ is an alkylene group having 2 or 3 carbon atoms, C _n H _{2n + 1} represents a branched or straight chain alkyl group. n is determined from m and R ₁ so that HLB falls within the above range. n is preferably in the range of 5 to 14, and 6 or more 1
It is more preferably 3 or less. However, when m = 0, n is preferably 8 or more from the viewpoint of preventing volatilization. For example, Table 1 shows the calculation results of HLB when R ₁ = -CH ₂ CH _2- , m = 2.

[Table 1]

[0006]

Embedded image CH ₂ ═CH—COO — (— R ₁ —O—) _j —Ph—C _k H _{2K + 1} (2) Ph is a phenylene group, j is an integer from 0 to 6, and R ₁ is the number of carbon atoms. The 2 or 3 alkylene group, C _k H _{2k + 1} , represents a branched or straight chain alkyl group. k is determined from j and R ₁ so that the HLB is in the above range. However, when j = 0, k is preferably 6 or more from the viewpoint of volatilization prevention. _{R 1 = -CH 2 CH 2 -} , when j = 1, k is 6
The range of 14 is preferable, and 7 or more and 13 or less is more preferable. In the above example, the HLB is controlled by having a relatively long alkyl group at the terminal, but if the HLB satisfies the above requirements, the alkyl group does not need to be at the terminal, and for example, formula (3) or (4) Good characteristics can be exhibited even in such a structure.

CH ₂ = CH-COO- (CH ₂ ) ₁₀ -O-CH ₃ (HLB = 4.5) (3) CH ₂ = CH-COO- (CH ₂ ) ₁₂ -OCOCH ₃ (HLB = 4.7) (4) In the above examples, the case where a single monofunctional acrylate is used has been described, but depending on the liquid crystal used, the case where the single monofunctional acrylate does not sufficiently adjust the characteristics may occur. . In such a case, it is preferable to use a mixture of a plurality of monofunctional acrylates. HLB in mixed system
Since the additive property of is satisfied, it is possible to adjust arbitrary HLB by changing the composition according to the liquid crystal, and it is possible to exhibit excellent characteristics. H of n component mixture system
The LB value is given by the following expression (A).

[Equation 1] Here, HLB _i represents the HLB value of the i-th component, and C _i represents the weight fraction thereof. The HLB of the mixed system also needs to satisfy the above range, that is, 2.5 or more and 7.0 or less. When used in a mixed system, there is no limitation on the HLB of each monofunctional acrylate, and each component does not necessarily have to satisfy the above-mentioned preferable HLB range. For example, a mixture of the compounds represented by the structural formulas (5) and (6) in a weight ratio of 1: 1 (H
LB = 3.9) can also be preferably used.

Embedded image _{CH 2 = CH-COO- (CH} 2) 13 CH 3 (HLB = 1.8) ... (5) CH 2 = CH-COO- (CH 2 CH 2 -O) 4 - (CH 2) ₇ CH ₃ (HLB = 6.0) (6) Although various monofunctional acrylates can be used in the mixed system, the following general formula is used from the viewpoint of availability, synthesis, low vapor pressure, and the like. The materials (7) and (8) can be shown as particularly preferable examples.

Embedded image CH ₂ ═CH—COO— (R ₁ —O—) _p —C _p H _2q-1 (7) p is an integer from 0 to 6, and q is 8 to 18 when p is 0.
Represents an integer of 6 to 18 when p is 1, and an integer of 1 to 18 (preferably 4 to 18) in other cases. _{CH 2 = CH-COO (CH} 2 CH 2 O-) u -Ph-C v H 2v + 1 ... (8) u is from 0 to 6 integer, v is an integer of 4 to 18.

Another preferred monofunctional acrylate is
Examples thereof include acrylates having a cycloaliphatic group such as an isobornyl group, a norbornyl group, an adamantane ring, and a cyclohexyl group.

[Chemical 6] The content of the monofunctional acrylate in the prepolymer composition depends on the types of the monofunctional acrylate and the polyfunctional acrylate used, but is generally 20% by weight or more 8
It is preferably 0% by weight or less, and 30% by weight to 7% by weight.
It is more preferably 0% by weight. When the content of the monofunctional acrylate is too small, the hysteresis becomes large, the size of the liquid crystal droplet becomes small, the shape becomes inappropriate and the light scattering property is lowered, and the operating voltage becomes high. Resulting in. Conversely, if the content is too high,
This is not preferable because it causes problems that the size of the liquid crystal droplets becomes too large and the dispersion structure cannot be obtained due to the decrease in the reaction rate.

As the bifunctional acrylate used in combination with the monofunctional acrylate, it is necessary to use a compound having an HLB value in the range of 3.5 to 11.0, preferably 4.
Those having an HLB value of 0 to 10 are preferable. As such a bifunctional acrylate, urethane acrylate, ester acrylate, ether acrylate, alkyl acrylate or the like can be used. The following can be illustrated as particularly preferable bifunctional acrylates.

Embedded image Examples of _{CH 2 = CH-CO-R} 2 -CO-CH = CH 2 ... (14) R 2 (A) -O (CH 2 CH 2 -O) n - (n = 2~5) For example _{-O (CH 2 CH 2 -O)} 4 - -O (CH 2 CH 2 -O) 3 - (B) -O [CH (CH ₃₎ CH ₂ -O] _n - _(n = _2~16) For example -O [CH (CH ₃₎ CH ₂ -O] ₃ - -O [CH (CH ₃₎ CH ₂ -O] ₆ -

[Chemical 8]

[Chemical Formula 9] (D) -OR₃-COO-R_Four-OR₃: Alkylene group C_nH2_n R_Four: Alkylene group C_mH2_m  n and m are integers of 2 or more, and m + n is 5 or more and 18 or less. For example -O-CH₂-C (CH₃)₂-CH₂-OCO-C (CH₃)₂-CH₂-O- -O-CH₂-C (CH₃)₂-CH₂-OCO- (CH₂)_Five-O-

[Chemical 10]

Further, the following compounds can be exemplified as other preferable examples.

[Chemical 11] One kind of bifunctional acrylate may be used, but a plurality of kinds may be used for the purpose of adjusting HLB and adjusting the crosslink density. In this case, the HLB of the mixture is 3.
It is necessary to satisfy the condition of 5 to 11.0.

A polyfunctional acrylate having 3 or more functional groups can be added to the composition of the present invention with an upper limit of 8% by weight based on the prepolymer. Addition of a polyfunctional acrylate has the excellent characteristics that the hysteresis can be made small and the response speed can be made fast, but on the other hand, there is also the drawback that the drive voltage rises. Therefore, the addition of 8% by weight or less causes a slight increase in the driving voltage, has a slight margin in the driving voltage, and is an extremely effective improving means for applications requiring high-speed response and / or low hysteresis. The upper limit of the addition amount is 8% by weight, but 6% by weight or less is preferable,
It is more preferably 5% by weight or less. Although the lower limit depends on the polyfunctional acrylate used, it is generally preferably 0.2% by weight or more. The polyfunctional acrylates that can be used are trifunctional acrylates and tetrafunctional acrylates. Specific examples of polyfunctional acrylates include:

[Chemical 12] In addition to the above, polyfunctional polyester acrylate, polyurethane acrylate and the like can also be used. Regarding the number of functional groups, a trifunctional acrylate is most preferable because the higher the functional number, the more markedly the operating voltage rises.

The polymerization initiator to be added is preferably a photopolymerization initiator from the viewpoints of workability, control of dispersion structure, storage stability and the like. As the photopolymerization initiator that can be used, known materials can be used, and examples thereof include biacetyl, acetophenone, benzophenone, Michler's ketone, benzyl, benzoin alkyl ether, benzyl dimethyl ketal, 1-hydroxy-2-methyl-1-phenyl. Propan-1-one, 2
-Chlorothioxanthone, methylbenzoyl formate, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one, diethoxyacetophenone, 1-hydroxycyclohexylphenyl ketone, 2,2-dimethoxy-1, 2-diphenylethane
1-on and the like can be exemplified. Among them, benzoin ethyl ether, benzoin butyl ether, benzoin alkyl ether such as benzoin isopropyl ether, 1-hydroxycyclohexyl phenyl ketone, and the like from the viewpoint of obtaining high reliability and high charge retention rate.
2,2-dimethoxy-1,2-diphenylethane-1-
ON is particularly preferably used. The addition amount of the polymerization initiator is preferably 1% by weight or more and 10% by weight or less, and more preferably 1.5% by weight or more and 8% by weight or less, based on the total amount of the prepolymer. If the amount of the initiator added is too small, the polymer and the liquid crystal do not phase-separate even by irradiation with ultraviolet rays, or even if the phase-separation occurs, the size of the liquid crystal droplets becomes too large, and the light scattering property decreases. I will end up.
On the other hand, when the amount of the initiator is too large, there are problems that the size of the liquid crystal droplets becomes too small and the operating voltage rises and the electrification retention rate decreases.

As the liquid crystal used in the composition, a nematic liquid crystal composition having a positive dielectric anisotropy is preferably used. Examples of the liquid crystal constituting the liquid crystal composition include conventionally known biphenyl and terphenyl.
nyl), phenylcyclohexane (phenylcy)
Clohexane), biphenylcyclohexane (b
iphenylcyclohexane), benzoic acid phenyl ester (phenylbenzoate), cyclohexanecarboxylic acid phenyl ester (cyclo)
hexanecarboxylicacid phen
yl ester), phenylpyrimidine (pheny)
lpyrimidine), phenyldioxane (ph
enyldioxane), tran (tolane),
1-phenyl-2-cyclohexylethane (1-phe
nyl-2-cyclohexyl-ethane),
1-phenyl-2-biphenylethane (1-phenyl
1-2-2-biphenyl-ethane), 1-cyclohexyl-2-biphenylethane (1-cycloh
exyl-2-biphenyl-ethane, biphenylcarboxylic acid phenyl ester (biphenyl)
lcarboxylic acid phenyls
ter), 4-cyclohexylbenzoic acid phenyl ester (4-cyclohexylcarboxylica)
cid phenyl ester) etc. as the skeleton,
A liquid crystal having an alkyl group, an alkoxy group, a cyano group as a polarity-imparting group for imparting positive dielectric anisotropy, a halogen group or the like as a substituent in the long axis direction of the molecule can be used. The dielectric anisotropy of each component constituting the liquid crystal composition may be all positive, but a mixed composition in which the entire dielectric anisotropy is positive with a positive / negative mixture may be used. In particular, when driving by using an active element, a high charge retention rate is required, and thus it is necessary to use a high resistance liquid crystal. For such applications, among the above liquid crystals, a liquid crystal having a halogen group as a polarity-imparting group as a component having a positive dielectric anisotropy is particularly preferably used. If necessary, a dichroic dye or a photosensitizer may be added to the composition for the purpose of adjusting the photosensitive wavelength. When a polymer-dispersed liquid crystal display device is manufactured using the composition to which the dichroic dye is added, the device can be operated in the guest-host mode. The composition ratio of the liquid crystal to the total amount of the composition is preferably 70% by weight or more and 90% by weight or less, and more preferably 70% or more and 85% or less. When the amount of liquid crystal is too small, the operating voltage becomes high, and when it is too large, the polymer and liquid crystal do not phase separate due to UV irradiation, or the size of the liquid crystal drop becomes too large even if phase separation occurs. As a result, light scattering is reduced. To prepare a polymer-dispersed liquid crystal display device using the prepolymer / liquid crystal composition according to the present invention, an empty liquid crystal is prepared by a conventionally known method using glass having a pixel electrode on its surface or a transparent substrate. A cell may be prepared, and then the composition may be injected into the space between the substrates, and the cell may be irradiated with ultraviolet rays. In addition, a method of applying the composition to one side of the substrate and then stacking the counter substrate and then irradiating with ultraviolet rays, or a method of irradiating with ultraviolet light with the composition applied to the one side of the substrate and then superposing the counter substrate, etc. Can also be adopted. The wavelength of ultraviolet rays to be irradiated depends on the type of polymerization initiator used, but is generally 300.
The range of nm to 420 nm is preferable, and the range of 330 nm to 400 nm is more preferable. The intensity of the irradiation light is preferably in the range from 20 mW / cm ² of 300 mW / cm ^2. The temperature at which the ultraviolet rays are irradiated (polymerization temperature) depends on the phase separation temperature of the composition. The term "phase separation temperature" as used herein means a temperature at which the composition causes phase separation between the liquid crystal and the prepolymer at a temperature lower than that. The polymerization temperature must be higher than the phase separation temperature of the composition and not higher than 20 ° C. If the temperature is too low, the elements will be uneven,
If it is too high, the operating voltage will rise rapidly. Next, a liquid crystal display device using the prepolymer / liquid crystal composition according to the present invention will be described. The liquid crystal display device according to the present invention has a structure in which a dispersion system composed of a polymer and a liquid crystal produced by the reaction of the above-mentioned prepolymer / liquid crystal composition is sandwiched between a pair of substrates. FIG. 1 is a schematic sectional view of an embodiment of the liquid crystal display device according to the present invention. Electrode 12,
A pair of substrates 11 and 21 each having 22 are arranged to face each other with a space therebetween, and a liquid crystal layer 30 is formed in a minute gap between the substrates. FIG. 2 schematically shows an example of a cross-sectional structure of the liquid crystal layer. The liquid crystal 30b is dispersed by the minute voids formed by the support 30a, and the alignment of the liquid crystal is disturbed by the wall effect of the support when no voltage is applied. ing. A liquid crystal is arranged in one direction by applying a voltage between the upper and lower electrodes to display. The liquid crystal display element according to the present invention is characterized in that the hysteresis characteristic of the voltage-transmittance characteristic can be reduced, it can be driven at a low voltage, light scattering is strong when no voltage is applied, and it has a high-speed response. Have. The thickness of the liquid crystal layer formed by the liquid crystal and the support is preferably 3 to 30 μm, more preferably 3 to 15 μm from the viewpoint of driving voltage and contrast. If it is too thick, the driving voltage increases, which is not preferable, and if it is too thin, the contrast decreases. The size of the liquid crystal droplets is preferably 0.5 μm to 4 μm, and 1.5 μm to 3.5 μm.
Is more preferable. If it is less than this, the contrast decreases and the driving voltage also increases. On the other hand, if it is too large, the contrast decreases and the response speed becomes slow, which is not preferable.

[0013]

【Example】

Example 1 Table 2 below showing HLB of 5.3 as the monofunctional acrylate.
H1 of M1 is 10.0 as a bifunctional acrylate.
Using an acrylate represented by D1 in Table 3 below,
Both were mixed at a weight ratio of 50/50. 2-hydroxy-2-methyl- which is a photopolymerization initiator
3% by weight of 1-phenylpropan-1-one was added,
Polymerizable prepolymer composition 1 was prepared. A liquid crystal / prepolymer composition 2 was prepared by mixing 1 and a cyanobiphenyl liquid crystal BL007 (manufactured by Merck & Co., Inc.) so that the liquid crystal concentration was 75% by weight. Two glass substrates each having an electrode made of a transparent conductive film on the surface were superposed with a 7 μm spacer interposed therebetween, and the ends were fixed with an adhesive. The composition 2 was injected into the space between the substrates and irradiated with ultraviolet rays from a high pressure mercury lamp. The temperature of injecting the composition and irradiating the composition with ultraviolet light was set to a temperature higher by 5 to 10 ° C. than the phase separation temperature of the composition. Also,
The irradiation energy was 80 mW / cm ² . Regarding the characteristics of the obtained display device, the voltage-transmittance characteristic and the response speed were measured using a measurement system in which the optical system has an acceptance angle of 20 °. The liquid crystal display device had the following characteristics and had excellent characteristics. T (0V) = 8%, V90 = 14V, γ = 3.8,
H = 9%, response speed = 34 ms Here, T (0V) is the transmittance when no voltage is applied, V10, V
50 and V90 are voltage values at which the transmittance changes are 10%, 50%, and 90% of the total change amount, respectively, and γ is V90 / V.
10 is a parameter representing steepness, H is ΔV50
/ V50, which is a parameter indicating the magnitude of hysteresis, ΔV50 is expressed by the difference between V50 at the time of voltage rise and voltage decrease, and the response speed by the sum of the response times of the 90% change amount at the time of rising and falling. In addition, monofunctional acrylate is M
The weight ratio of A, the bifunctional acrylate to DA, and MA to the prepolymer composition is represented by CMA.

Comparative Examples 1 to 3 Liquid crystal display devices were produced in the same manner as in Example 1 except that M6, M7 or M8 shown in Table 2 below was used instead of M1. When M6 was used, T (0V) was 10%, but V90 was as high as 18V. When M7 was used, T (0V) was 30%, resulting in extremely low scattering characteristics. In the case of M8, in addition to high voltage (V90 = 23V), low scattering [T (0V) = 40%], large hysteresis (H = 18%), and
The response speed has become very large (370m
s).

Examples 2 to 6 D in Table 3 below was used as the difunctional acrylate in Example 1.
A liquid crystal display element was manufactured using 2-D6. All of them gave good characteristics as shown in the table. No. DAT (0V) V90 γ H Response speed 2 D2 7 12 2.6 2.6 9 60 3 D3 5 8 2.3 2.3 9 49 4 D4 4 9 2.5 2.5 10 42 5 5 D5 9 9 3.5 8 40 6 D6 513 3.0 12 20

Comparative Examples 4 to 5 D as shown in Table 3 below as a bifunctional acrylate in Example 1.
A liquid crystal display element was manufactured using 7 to D8. As shown in the table, the driving voltage of these devices increased. No. DA V90 Comparison 4 D7 19 Comparison 5 D8 19

Example 7 HLB of 5.3 as a monofunctional acrylate
M1 was used as a bifunctional acrylate and D3 in Table 3 below having an HLB of 8.2 was used, and both were mixed at a weight ratio of 50/50. 3% by weight of benzoin propyl ether, which is a photopolymerization initiator, was added to this composition to prepare a polymerizable prepolymer composition. A liquid crystal / prepolymer composition was prepared by mixing the composition and a halogenated terphenyl liquid crystal TL202 (manufactured by Merck) so that the liquid crystal concentration was 75% by weight. After that, a liquid crystal display element was manufactured in the same manner as in Example 1. This device exhibited excellent characteristics as shown in the table below. The charge retention rate of this device measured with a measurement signal of 10 V and 30 Hz is 95% or more.
There was almost no change when irradiated with 0 lux of simulated sunlight. No. T (0V) V90 γ H Response speed 13 8 10 2.1 8 22

Examples 8 to 16 In Example 7, a bifunctional acrylate and a monofunctional compound were combined as shown in the following table to prepare a liquid crystal display device. These also gave good properties as shown in the table. No. DA MAT (0V) V90 γ H Response speed 8 D3 M2 8 7 2.0 3 45 9 D3 M3 9 8 2.0 5 5 50 10 D3 M4 7 11 2.1 12 12 46 11 D3 M5 8 10 10 2.4 12 50 12 D3 M9 10 9 1.9 12 70 13 D1 M1 15 9 3.0 3 60 14 D2 M1 10 8 2.1 8 38 15 15 D4 M1 7 8 2.1 2.1 10 32 16 D5 M1 10 8 2.3 10 33

Example 17 A liquid crystal display device was prepared in the same manner as in Example 7, except that D9 shown in Table 3 below having HLB of 4.2 was used as the bifunctional acrylate and CMA was 70%. No. DA MAT (0V) V90 γ H Response speed 23 D9 M1 9 8 2.2 7 31

Example 18 A liquid crystal display device was produced in the same manner as in Example 7 except that the monofunctional acrylate prepared by mixing M1 and M10 shown in Table 2 below in a ratio of 1: 1 was used. This had excellent properties as shown in the table below. No. T (0V) V90 γ H Response speed 24 8 7 1.8 5 43

Comparative Examples 6 and 7 In Example 7, the monofunctional acrylate M shown in Table 2 below was used.
A liquid crystal display device was manufactured using 11 or M6, but the voltage-transmittance characteristics of these devices were not saturated even when 30 V was applied, and the scattering when no voltage was applied was extremely weak. No. DA MAT (0V) V90 Comparison 6 D3 M11 15 25 Comparison 7 D3 M6 22 25

Examples 19 to 22 In Example 7, benzoin ethyl ether, benzoin butyl ether, 1-hydroxycyclohexyl phenyl ketone, 2,2-dimethoxy-1, as an initiator.
A liquid crystal display device was produced in the same manner except that 2-diphenylethan-1-one was used. These elements are also used in Example 7.
It had high display performance and high reliability. In addition,
These are suitable for both active and passive types.

Example 23 In Example 7, 2-methyl-1- [4 was used as an initiator.
A liquid crystal display device was produced in the same manner except that-(methylthio) phenyl] -2-morpholinopropanone was used. The display property of this product was similar to that of Example 7, but the holding ratio was a little low at 70%, and the holding ratio was slightly lowered in the light resistance test.

Example 24 A liquid crystal display device was manufactured by adding 1.5% by weight of trimethylolpropane triacrylate to the prepolymer composition in Example 9. This is a little V90
Although a rise was observed, the response speed and hysteresis were greatly improved. No. T (0V) V90 γ H Response speed 9 9 8 2.0 5 50 24 24 9 9 2.0 2.5 30

Examples 25 to 28 In Example 1, instead of Ml, M2 to M5 shown in Table 2 below were used.
A liquid crystal display element was similarly prepared using. In all of these devices, V90 is 15V or less and T (0V) is 10V.
%, H was 12% or less, and the response speed was 50 ms or less, which had excellent characteristics.

Example 29 In Example 1, instead of M1, M6 and M7 in Table 2 below were used.
1: 1 mixture of was used as the monofunctional acrylate. The monofunctional acrylate has an HLB of 5.0. It was confirmed that the liquid crystal display device of the present example gave almost the same characteristics as those of Example 1, and that even if a mixed system of monofunctional acrylates was used, it was possible to significantly improve the characteristics by controlling the HLB.

[0027]

[Table 2]

[0028]

[Table 3]

[0029]

[Effect] The liquid crystal / prepolymer composition of the present invention gives a structure in which liquid crystal droplets are dispersed in the polymer by polymerization, and the shape and size of the droplets are extremely uniform, and the ideal size and shape are obtained. The feature is that it is easily given. Therefore, the obtained liquid crystal display element according to the present invention is characterized in that it can be driven at a low voltage and the response speed is fast. Further, since the obtained element has a clear threshold value characteristic and is excellent in steepness of voltage-transmittance characteristic, it has an advantage that time-division driving which has been impossible in the past can be performed. Furthermore, since the liquid crystal display device manufactured by the liquid crystal / prepolymer composition according to the present invention has a very small hysteresis of voltage-transmittance characteristics, it is possible to perform gradation display. In addition, by selecting a polymerization initiator, it is possible to provide a highly reliable liquid crystal display device. Further, the prepolymer composition of the present invention, even when using a halogen-substituted liquid crystal having a high retention rate that has been conventionally difficult to control the structure, good characteristics are obtained, and since the charge retention rate is high, Active element drive is possible.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of an example of a liquid crystal display element of the present invention.

FIG. 2 is a diagram schematically showing a cross-sectional structure of a liquid crystal layer of the liquid crystal display element of FIG.

[Explanation of symbols]

 11 substrate 12 electrode 21 substrate 22 electrode 30 liquid crystal layer 30a polymer layer support 30b liquid crystal

Claims (8)

[Claims] 1. A liquid crystal / prepolymer composition comprising a prepolymer composition, a polymerization initiator and a liquid crystal, wherein phase separation between the liquid crystal and the polymer is induced by polymerization, wherein the prepolymer composition has a double bond. A monofunctional acrylate H mainly comprising a bifunctional acrylate having two and a monofunctional acrylate having one double bond.
A liquid crystal / prepolymer composition, wherein the LB value is 2.5 or more and 7.0 or less, and the HLB value of the bifunctional acrylate is 3.5 or more and 11 or less. 2. The liquid crystal / prepolymer composition according to claim 1, wherein the monofunctional acrylate is a mixture of two or more monofunctional acrylates. 3. The liquid crystal / prepolymer composition according to claim 1, wherein the difunctional acrylate is a mixture of two or more difunctional acrylates. 4. The liquid crystal / prepolymer composition according to claim 1, 2 or 3, wherein a polyfunctional acrylate having 3 or more functional groups is mixed in an amount of 8% by weight or less based on the total amount of the prepolymer. 5. The liquid crystal / prepolymer composition according to claim 1, 2, 3 or 4, wherein the polymerization initiator is a photopolymerization initiator and the addition amount thereof is 1% or more and 10% or less with respect to the total amount of the prepolymer. object. 6. The liquid crystal / prepolymer composition according to claim 1, wherein the amount of liquid crystal in the total amount of the composition is 70% by weight or more and 90% by weight or less. 7. The method according to claim 1, 2, 3, 4, between a pair of substrates.
A liquid crystal display device comprising a liquid crystal and a polymer phase-separated structure formed by a polymerization reaction of the liquid crystal composition according to the item 5 or 6. 8. A phase in which a phase separation structure of a liquid crystal and a polymer includes a liquid crystal having a positive dielectric anisotropy and a liquid crystal phase having a halogen group as a polarity-imparting group, and a nematic phase having a positive dielectric anisotropy as a whole. And the phase separation structure is at least one polymerization initiator selected from the group consisting of benzoin alkyl ether, 1-hydroxycyclohexyl phenyl ketone, and 2,2-dimethoxy-1,2-diphenylethan-1-one. The liquid crystal display element according to claim 7, which is formed by using.