JPH05289063A - Liquid crystal display element - Google Patents

Abstract

PURPOSE:To obtain excellent thermal stability, stability with lapse of time, electrical response characteristic, etc., bright and good contrast. CONSTITUTION:This liquid crystal display element is a display element having a light control layer 14 between substrates 12 having electrode layers 11 and the light control layer 14 has a three-dimensional network matrix high polymer contg. >=60wt.% iterative unit of the crotonate expressed by formula and has the structure formed by dispersing liquid crystals as a continuous phase into the three-dimensional network of the high polymer. (In the formula, R denotes 3 to 12C branched alkyl group 3 to 12C cycloalkyl group, 2 to 6C substd. alkyl group having a substituent of 3 to 14C cyclic structure, 3 to 10C substd. cycloalkyl group having the substituent of the cyclic structure or cycloxane hydrocarbon group. Heteroatoms may be incorporated into the respective groups mentioned above and may be substd. with halogen atoms as well).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device,
More specifically, it shows a response of light scattering-light transmission by turning on / off an externally applied voltage, and can be made large in size, and is a liquid crystal display that can be used as a display element for displaying characters or figures and a filter for adjusting the amount of light. Regarding the device.

[0002]

2. Description of the Related Art In a display using a liquid crystal or a dimming method, a relatively quick response can be made with a small amount of electric energy, and a display area from a small area to a large area can be displayed. Various developments have been made.

Liquid crystal display elements have heretofore been mainly ones that utilize the light-transmitting property of liquid crystal, and since a polarizing plate is required for these display elements, it is possible to obtain a liquid crystal display element that is bright and has good contrast. Has the drawback of being difficult.

Further, with the increase in area of liquid crystal display elements, in recent years, a spacer and a gap adjusting agent for making the liquid crystal layer have a uniform thickness over the entire display element and maintaining the uniform thickness of the liquid crystal layer. There is a need for a device such as the above, and further, a substrate material that is hard and difficult to deform, such as glass, is required.

Therefore, in order to solve the above-mentioned drawbacks, a method of encapsulating liquid crystal in a capsule and dispersing it in a polymer (US Pat. No. 4,435,047, etc.), phase separation of liquid crystal / oligomer / ultraviolet curing type monomer. After dispersing the liquid crystal by examining the structure and selecting the optimal combination,
A method of irradiating ultraviolet rays to form a liquid crystal continuous phase in the three-dimensional network of the resin (Japanese Patent Laid-Open No. 2-29487) has been studied.

However, in the method of dispersing the liquid crystal in the polymer by the above-mentioned encapsulation method, it is necessary to select the liquid crystal and the encapsulating agent, examine the dispersion conditions, etc.
Although excellent properties are exhibited under limited optimum conditions, when the properties of the liquid crystal are greatly different, there is a drawback that each condition must be optimized again in accordance with the properties of the liquid crystal.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to use a polymer matrix that has low miscibility with liquid crystals and is thermally stable, does not require a polarizing film, has a simple structure, and is easy to manufacture. To provide a liquid crystal display element having excellent electrical response.

[0008]

According to the present invention, there is provided a display device having a light control layer between a substrate having an electrode layer,
The light control layer has a three-dimensional network matrix polymer containing 60% by weight or more of repeating units of crotonic acid ester represented by the following general formula (2) (hereinafter referred to as crotonic acid ester unit 1), and Provided is a liquid crystal display device having a structure in which liquid crystals are dispersed as a continuous phase in a three-dimensional network matrix of a polymer.

[0009]

[Chemical 2]

The present invention will be described in more detail below.

In the liquid crystal display device of the present invention, the light control layer provided between the substrates has a specific three-dimensional network matrix polymer, and the liquid crystal is contained in the three-dimensional network matrix of the polymer. Is dispersed as a continuous phase.

In the present invention, the three-dimensional network matrix polymer preferably has a number average molecular weight of 5,000 to 10
Any polymer having a three-dimensional network structure in which liquid crystals can be dispersed as a continuous phase is acceptable as long as it is a polymer of 00000, and cross-linking polymerization is not always necessary. The component constituting the repeating unit of crotonic acid ester contained as a constitutional unit of the polymer is the crotonic acid ester unit 1 represented by the general formula 2. In this case, examples of the hetero atom which may be contained in each group in the formula in Chemical formula 2 include a nitrogen atom, an oxygen atom, a phosphorus atom and a sulfur atom, and the halogen atom is a chlorine atom. ,
Examples thereof include a fluorine atom and an iodine atom.

Specific examples of the crotonic acid ester having a hydrocarbon group include isopropyl crotonic acid, tert-butyl crotonic acid, cyclohexyl crotonic acid, csec-butyl crotonic acid and crotonic acid-4.
-Having a branched alkyl group having 3 to 12 carbon atoms such as methyl-2-pentyl, isoamyl crotonic acid, 2-ethylhexyl crotonic acid, and nonyl crotonic acid, or a cycloalkyl group or a substituent having a cyclic structure having 3 to 14 carbon atoms. Crotonic acid ester having a substituted alkyl group having 2 to 6 carbon atoms; trimethylsilyl crotonate, 3-tris (trimethylsiloxy) silylpropyl-crotonate, 3-
Crotonic acid esters having siloxane-based hydrocarbon groups such as ((pentamethyl) disiloxanyl) propyl-crotonate; N, N-dimethylaminoethyl crotonate, 1-butoxy-2-propyl crotonate, 2-cyanoethyl crotonate, glycidyl- Crotonic acid esters containing heteroatoms such as crotonate, diethylphosphonomethyl-crotonate, 2-methylthioethyl-crotonate; perfluorooctylethyl-crotonate, trifluoromethyl-crotonate, pentafluoroethyl-crotonate, hexafluoroisopropyl-crotonate, 1 Preferred examples thereof include a crotonic acid ester substituted with a halogen atom such as chloroisopropyl crotonate.

In the present invention, the content ratio of the crotonic acid ester unit 1 contained as a constituent unit of the three-dimensional network matrix polymer is 60% by weight or more in the three-dimensional network matrix polymer. When the content ratio of the repeating unit is less than 60% by weight, a desired three-dimensional network matrix polymer cannot be obtained and the performance as a liquid crystal display device is significantly deteriorated.

In the present invention, other copolymerizable monomers other than the crotonic acid ester capable of constituting the three-dimensional network matrix polymer include, for example, styrene, α-methylstyrene, chloromethylstyrene; ) Acrylic acid and its lower linear alkyl esters;
Crotonic acid and its lower linear alkyl esters; fumaric acid and its lower alkyl esters; maleic acid and its lower alkyl esters; itaconic acid and its lower linear alkyl esters; methyl vinyl ether, n-
Vinyl ethers such as butyl vinyl ether; vinyl esters such as vinyl acetate, vinyl propionate, vinyl caproate, vinyl benzoate; allyl esters such as allyl acetate, allyl benzoate; acrylonitrile, vinyl chloride, vinylidene chloride, ethylene, butadiene , Chloroprene, isoprene, isobutylene and the like can be preferably mentioned, and when used, they can be used alone or as a mixture.

In the present invention, in order to prepare the polymer constituting the three-dimensional network matrix polymer, the crotonic acid ester alone or the crotonic acid ester and the other copolymerization monomer are added to a conventional anionic polymer. Legal, etc.
Specifically, it can be obtained by a method of polymerizing in the presence of an anionic polymerization initiator, preferably at a reaction temperature of −100 to 100 ° C. for 0.5 to 30 hours. Specific examples of the anionic polymerization initiator include n-butyl lithium, tert-butyl lithium, n-amyl sodium, octyl potassium, sodium naphthalene,
Anthracene sodium, phenylmagnesium bromide,
Preferable examples include -sec-butylmagnesium chloride and triethylaluminum. The amount of the polymerization initiator used is 10 parts by weight based on 100 parts by weight of the raw material monomer.
The amount is preferably not more than 5 parts by weight, particularly preferably not more than 5 parts by weight.

In the present invention, the liquid crystal dispersed as a continuous phase in the three-dimensional network in the three-dimensional network matrix polymer capable of forming the light control layer is not particularly limited, and the liquid crystal is not limited. Any liquid crystal can be used as long as it can be used as a liquid crystal for a display device, and specific examples thereof include p-alkoxy-p′-alkylazobenzene, p-azoxyphenetol and other azoxy compounds, and p-alkoxy-p ′.
-Nitrogen base compounds such as -alkylbenzylideneaniline and p-alkoxybenzylidene-p'-alkylaniline, p-alkoxy-p'-cyanophenylbenzoic acid,
Phenyl ester compounds such as cholesteric benzoic acid, p-alkoxy-p'-cyanobiphenyl, biphenyl compounds such as p-alkoxy-p'-carboxylic acid biphenylalkyl ester, phenylcyclohexane compounds, dioxane compounds, pyrimidine compounds Etc., and may be used alone or as a mixture.

In the present invention, as a method for producing the light control layer, the polymer constituting the three-dimensional network matrix polymer and the liquid crystal are dissolved in a common solvent, and a known method such as water surface development is used. It can be prepared by evaporating a common solvent by a method, a solvent casting method, or the like.
At this time, the polymer constituting the matrix polymer and the liquid crystal have low miscibility and coagulate independently in the common solvent evaporation process. Therefore, the polymer constituting the matrix polymer has a tertiary structure. Form the original mesh structure,
And the liquid crystal can be dispersed as a continuous phase in the three-dimensional network. The composition in the common solvent is not particularly limited, but considering the dispersion of the liquid crystal, the network state of the matrix polymer, etc., the weight ratio of the matrix polymer / liquid crystal is 1 / 0.25 to It is preferably ⅕, and as the volatile organic solvent, general-purpose organic solvents such as chloroform, ethylene dichloride, benzene and toluene can be preferably mentioned. Although the thickness of the light control layer is arbitrary, it can be usually used in the range of 5 to 200 μm.

The liquid crystal display device of the present invention can be produced, for example, by providing the substrate having an electrode layer with the above-mentioned light control layer which is dried, between the substrates. Various substrates can be used as the substrate having the electrode layer. For example, in order to manufacture a cell for a liquid crystal display, ITO (indium oxide), NES
A transparent glass substrate having an electrode layer of A (tin oxide) or the like can be preferably used, and a substrate obtained by applying an electrode layer to various transparent resins can also be used. Further, when the dimming layer is provided between the substrates, the dimming layer may be brought into direct contact with the substrate having the electrode layer, but in order to further provide adhesiveness, the dimming layer and A polymer film or the like can be inserted between the glass substrate and the glass substrate.

[0020]

The liquid crystal display device of the present invention uses a three-dimensional network matrix polymer containing a repeating unit of crotonic acid ester, which is immiscible with liquid crystal, as a component constituting the light control layer. Stability and aging stability, and since a dimming layer can be formed without the need for a polarizing plate, the liquid crystal has excellent electrical response characteristics and is bright and can provide good contrast. .

[0021]

EXAMPLES The present invention will be described in more detail based on the synthetic examples and examples, but the invention is not limited thereto.

[0022]

[Synthesis Example 1] 20 ml of dry toluene was added, and the atmosphere was sufficiently replaced with dry nitrogen, and the glass ampoule cooled to 0 ° C
1 mol benzene solution of tertiary butyl lithium 1 m
1 was added, and 5 ml of tert-butyl crotonic acid was added with vigorous stirring. Then, after stirring for about 1 hour, a small amount of methanol was added to stop the polymerization reaction. After the polymerization, the content is dissolved in benzene and poured into a large amount of methanol to precipitate the polymer, which is separated by filtration, sufficiently washed with methanol, and dried under reduced pressure to give a weight average molecular weight of 355,000.
Poly (tertiary crotonate) having a polydispersity of 1.55 was obtained.

[0023]

Example 1 Poly (tert-butyl crotonate) (hereinafter abbreviated as PtBCA) with a weight ratio of 1/1 and liquid crystal (trade name "E7", cyanobiphenyl mixed liquid crystal manufactured by BDH)
And were dissolved in chloroform to obtain a chloroform solution.
Then, as shown in FIG. 1, the solution is applied by a solvent casting method to a uniform thickness on the glass substrate 12 on which the ITO evaporation film 11 as an electrode layer is evaporated, chloroform is sufficiently evaporated, and PtBCA in PtBCA is evaporated. A 12 μm-thick light control layer 14 in which a continuous phase of liquid crystal was formed was formed in the three-dimensional network. Next, another glass substrate 12 having the ITO vapor deposition film 11 is placed so that the light control layer 14 is sandwiched, and an electrode 13 is further provided at one end of each of the ITO vapor deposition films 11 to provide the liquid crystal display device 10. Was produced. The obtained liquid crystal display device 10 was opaque because the liquid crystal array was random. Then, when a voltage of 100 V was applied between the electrodes 13 of the obtained liquid crystal display element 10, the light control layer 14 became transparent, and the switching behavior accompanying the voltage application was observed.

A part of the light control layer was extracted with ethanol heated to 50 ° C.
Over 0% was extracted. From this, it was confirmed that the light control layer had a three-dimensional network structure and the liquid crystal was continuously dispersed in the network.

[0025]

Examples 2 to 6 Using the monomers, polymerization initiators and solvents shown in Table 1, a polymer was synthesized in the same manner as in Synthesis Example 1 under each polymerization condition. Then, instead of PtBCA of Example 1, synthesized poly (crotonate-sec-butyl)
(Example 2), poly (4-tert-butylcyclohexylcrotonate) (Example 3), poly (isopropyl crotonate) (Example 4), poly (hexafluoroisopropyl crotonate) (Example 5), Poly (octafluoropentyl crotonate / methyl crotonate) (8/2
Polymer) A liquid crystal display device was produced in the same manner as in Example 1 except that the copolymer (Example 6) was used. As a result, electrical response characteristics similar to those of Example 1 were obtained.

[0026]

[Table 1]

[Brief description of drawings]

FIG. 1 is a perspective view of a liquid crystal display element of the present invention manufactured in Example 1.

[Explanation of symbols]

 10 Liquid Crystal Display Element 11 ITO Deposition Film 12 Glass Substrate 13 Electrode 14 Light Control Layer (Polycrotonate / Liquid Crystal)

Claims (1)

[Claims] 1. A display device having a light control layer between a substrate having an electrode layer, the light control layer containing 60% by weight or more of a repeating unit of crotonic acid ester represented by the following general formula 1. A liquid crystal display device comprising a three-dimensional network matrix polymer and having a structure in which liquid crystals are dispersed as a continuous phase in the three-dimensional network of the polymer. [Chemical 1]