JPH02236520A - High-polymer liquid crystal element - Google Patents

Abstract

PURPOSE:To suppress the decrease of a contrast and to allow the application to a display element, etc., of a large transmitted light quantity, light weight and large area by sealing a ferroelectric high-polymer liquid crystal by an adhesive agent of a low-temp. curing type, thereby preventing the generation of the orientation defects of the ferroelectric high-polymer liquid crystal at the time of sealing. CONSTITUTION:The ferroelectric high-polymer liquid crystal 2 of the high-polymer liquid crystal element formed by crimping the ferroelectric high-polymer liquid crystal 2 between a pair of plastic substrates 1 and 1a having electrodes is sealed by the adhesive agent 3 of the low-temp. curing type. Namely, the low-viscosity curing type adhesive agent 3 is poured into the gap part between the substrates 1 and 1a of the laminate at the temp. at which the ferroelectric high-polymer liquid crystal exhibits a chiral smectic phase or below the same. The adhesive agent is irradiated with energy rays, such as, for example, UV rays, and is thereby cured at the state when the adhesive agent penetrates uniformly to the circumference. Even if the ferroelectric high-polymer liquid crystal 2 comes into contact with the liquid adhesive agent 3 at this time, there is substantially no influence on the oriented state of the liquid crystal if the temp. is below the chiral smectic phase. The deterioration in orientation by a heat treatment, etc., at the time of sealing, etc., is prevented in this way and the decrease of the contrast of the liquid crystal element is prevented.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a polymer liquid crystal device using a ferroelectric polymer liquid crystal, and in particular to a polymer liquid crystal device that prevents a decrease in contrast due to alignment deterioration during sealing. Regarding elements.

[Prior Art] Conventionally, liquid crystal elements used in memories, displays, etc. have often been made of low-molecular-weight liquid crystals in order to meet requirements such as high-speed response. However, in recent years, due to the demand for large-screen displays and the simplification of mounting liquid crystal elements, so-called polymer liquid crystal compositions such as mixed systems of polymer liquid crystal compounds and low molecular liquid crystal compounds, or polymer liquid systems have been developed. Studies have been conducted on liquid crystal devices using .

Use of such a polymer liquid crystal composition is considered to be effective in the following respects.

■ Polymer liquid crystal compositions can be formed into films by solution coating, etc., and can be made into large-area liquid crystal elements, as well as being easy to thin and control the film thickness. This solves some of the difficulties associated with low-molecular liquid crystals, such as gap control between cell substrates.

(2) Some polymeric liquid crystal compositions can be oriented by stretching or the like, and there is a possibility that the alignment film used in low-molecular liquid crystals may become unnecessary.

■ When liquid crystal elements are used in memories, displays, etc., light-absorbing dyes are added to improve contrast. In the case of polymeric liquid crystal compositions, dyes such as dyes and pigments can be uniformly dispersed by utilizing the compatibility of polymers with dyes.

While this method was found to be effective, it had the drawback of slow response speed, making it unsuitable for high-speed video and rewriting applications. One way to solve the above drawbacks is to use ferroelectric polymer liquid crystals [N.A. Plat; et al.
ly@erBulleLin”), 12, 299
Page, (1984)] has been reported. This ferroelectric polymer liquid crystal has a significantly improved response speed compared to conventional polymer liquid crystals, and is therefore expected to be put into practical use. [Invention or problem to be solved 8] However, when trying to inject such a ferroelectric polymer liquid crystal into a cell such as a glass cell in the same way as a normal liquid crystal material, it is difficult to inject it into a cell such as a glass cell due to its high viscosity. Even in the polar phase state, it was difficult to easily fill the inside of the cell, and there were problems such as a long time being required for injection, and air bubbles getting mixed into the cell.

In addition, examples of polymer liquid elements in which a thin film is formed on a substrate by coating or film-forming a ferroelectric polymer liquid are disclosed in, for example, Japanese Patent Laid-Open No. 63-235916 and Japanese Patent Laid-Open No. 63-235916.
:L-257722, etc. However, there is no specific example of whether it is necessary to completely seal the polymer liquid crystal element without disturbing the orientation of the ferroelectric polymer liquid product.

The present invention was made in order to solve the problems of the prior art, and in a polymer liquid crystal element using ferroelectric polymer liquid crystal, the ferroelectric polymer liquid crystal is bonded to a low temperature curing type. The object of the present invention is to provide a polymer liquid crystal element which prevents alignment deterioration due to heat treatment during sealing by sealing with an agent, and which does not cause a decrease in contrast.

[A Thousand Steps to Solve the Problem] That is, the present invention provides a polymer liquid crystal element comprising a ferroelectric polymer liquid crystal sandwiched between a pair of plastic film substrates having electrodes. This is a polymeric liquid crystal element characterized by being sealed with a low-temperature curing adhesive.

The present invention will be explained in detail below.

FIG. 1 is a schematic diagram showing an example of a polymer liquid crystal device of the present invention. In the figure, plastic polarizing films are made of polarizing glass or polyvinyl alcohol made by adsorbing an iodine polymer and then uniaxially stretched, or polyvinyl alcohol or polyethylene terephthalate dyed with a dichroic dye and then uniaxially stretched. A ferroelectric polymer liquid crystal layer 2 is supported between the polarizing plates 5 and 5a and between the substrates 1 and la,
This shows a polymer liquid crystal device having a structure in which a laminate is sealed around the periphery with an adhesive 3. Also, in Figure 1,
Striped electrodes 6, 6a formed on the electrode-attached film 4.4a are provided on the outside of the substrate 1, la. FIG. 2 is a schematic diagram showing another example of the polymer liquid device of the present invention, and shows an example in which a substrate is provided on only one side. Depending on the device configuration, an adhesive layer may be provided between the substrate 1, la and the ferroelectric polymer liquid crystal layer 2, or an adhesive layer may be provided between the substrate 1, la and the ferroelectric polymer liquid crystal layer 2.
It may also have a laminated structure in which an insulating film or an alignment film is provided between the striped electrodes 6 and 6a.

The substrates 1 and la used in the present invention are preferably made of blastink film from the viewpoint of providing a large-sized and flexible liquid crystal element, and specific examples thereof include:
Polyethylene terephthalate, polycarbonate film, polyimide film, polymethyl methacrylate film, methyl methacrylate-styrene copolymer film, polystyrene, styrene-acrylic nitrile copolymer film, polypropylene film, low-density polyethylene film, high-density polyethylene film, Examples include vinyl chloride film, polytetrafluoroethylene finolem, polychlorotrifluoroethylene film, fluorinated ethylene-propylene copolymer film, polyarylate film, borisulfone film, cellulose film, polyetheretherketone film, etc. ．． The ferroelectric polymer liquid crystal used in the present invention includes chiral smectic C phase (S), H phase (S
mH'), I phase (Sml"), J phase (SaJ")
)． Side chain type polymeric liquid crystalline compounds and main chain type polymeric liquid crystalline compounds having K phase (SmK''), G phase (SAG'') or F phase (SmK'') can be used,
Specifically, the following may be mentioned, but the invention is not limited to these. (However, in the formula, * indicates an asymmetric carbon center.) +C H 2- C H }r- −+-CI1. -CII3-=-! = 1~2. k = 1 to 2, n = 4 to 18, m≧5 −+−C II , −CH}, −j=0 or l m≧5 +CII. -Cll}=- m≧5, n=4-18 j=0 or 1 m≧5 +CH. -CHe-=-! = 1-2, k = 1-2, j = 0 or 1, -+cH2-Ctlh = 1-2, k = 1-2. j = 0 or 1, n = 4 to 18, m≧5 n = 4 to 18, m≧5 These ferroelectric polymer liquid crystals can be used singly or as a mixture or copolymerization of two or more types, or in combination with low A composition suitable for device formation is used, such as by blending it with a molecular liquid crystal compound.

Furthermore, optically active polymer liquid crystals that can exhibit ferroelectricity by blending can also be used. A specific example is shown below. General low-molecular-weight ferroelectric liquid crystals are used for blending. However, when blending with low-molecular ferroelectric liquid crystals, compatibility must be considered.

The proportion of low molecular liquid crystal to be blended is 1 to 90%,
It is preferably in the range of 5 to 50%.

x = 0.1 ~ 1.0 m = 4 ~ 12. n≧3 (m2=2~l5. 2-15)()c+
y=1, recommendation=2~15) (l2) (■3=1~5) (4-1~3, 2=1~20) (l7) (m5=o~5) (s5=O~ 5) (l9) (ms 0-5) (ai5:O-5) In Kibatsu 1, after stretching a ferromagnetic polymer liquid crystal formed into a film, it is placed between the substrates. It is possible to obtain a resistor having the structure shown in FIG. 1 or 2 by sandwiching and crimping, or by layering the ferroelectric polymer liquid crystal and the substrate and then co-stretching them together with the substrate. These methods are effective in imparting orientation. In addition, conventionally known methods can also be used.

For example, methods such as heating and melting or dissolving in a solvent and coating on a substrate, and then cooling or evaporating the solvent, respectively, can be used.

In addition, it is possible to orient the rigid polymer liquid crystal layer formed on the substrate in this way by applying shear force to the coating, or by applying an alignment treatment such as an alignment film on the substrate in advance, and then It is also possible to use known alignment techniques such as slow cooling from a phase to a liquid crystal phase.

In the polymer liquid device of the present invention, the ferroelectric polymer liquid crystal layered as described above is sealed with a low-temperature curing adhesive. It is necessary to perform sealing at a temperature equal to or lower than that temperature, and if it is performed at a high temperature exceeding that temperature, it is not preferable because the alignment of the liquid crystal phase will be disturbed. In the present invention, by performing the above-mentioned sealing at the temperature of the chiral smectic phase of the polymer liquid crystal element used in practical use or at a temperature lower than that, the ferroelectric polymer liquid crystal can be removed from the chiral smectic phase from a high temperature range. It is possible to prevent orientation disturbance during phase transition when the temperature is lowered to .

A specific method for sealing is to fill the gap between the substrates 1 and la of the U-layer structure as shown in Figure 3 with a temperature at or below the temperature at which ferroelectric polymer liquid crystal exhibits a chiral smectic phase. A low-viscosity curable adhesive is poured into the adhesive, and once it has uniformly permeated the area, it is cured by irradiating energy rays such as ultraviolet rays. Alternatively, it is also possible to infiltrate a known cyanoacrylate-based instant adhesive in a dry air atmosphere in the same manner as above, and then leave it in air at normal humidity to harden it. .

In the present invention, a low-temperature curing adhesive is used, and specific examples thereof include cyanoacrylate-based adhesives such as α-cyanoacrylate, ethylcyanoacrylate, and methylcyanoacrylate, l-functional (meth)acrylic acid esters, and polyfunctional (meth)acrylic acid esters. Examples include acrylic ester oligomers made of functional (meth)acrylic esters.

[Function] The polymer liquid crystal device of the present invention is a polymer liquid crystal device in which a ferroelectric polymer liquid crystal is sandwiched between a pair of plastic film substrates having electrodes. The ferroelectric polymer liquid crystal is sealed with a low-temperature curing adhesive that cures at or below the temperature of the chiral smectic phase of the ferroelectric polymer liquid crystal. Even if it comes into contact with molecular liquid crystal or liquid adhesive, as long as the temperature is below the chiral smectic phase, there is almost no effect on the liquid crystal alignment state, so it prevents alignment deterioration due to heat treatment during sealing, and improves the contrast of the liquid crystal element. It is possible to prevent a decrease in

[Examples] Hereinafter, the present invention will be explained in more detail with reference to Examples. Example 1 Side-chain type ferroelectric polymer liquid crystal represented by the following structural formula (I) (n=20) (I)
30℃ 74℃ 83℃g
lass - Sac" - S+*A
Iso. Dissolve in diluted ethane,
This was coated on a polyethylene terephthalate (hereinafter referred to as PET) substrate with a thickness of 40 mm using a spin coating method, and the cycloethane was removed by heating to create a liquid crystal film layer with a thickness of 3 mm on the PET substrate. . On top of this liquid crystal film layer, a PUT film of 40 ml and 1 thickness is laminated,
The laminate obtained by passing it through a heat roll at about 85°C,
Uniaxial stretching was carried out at a temperature at which the ferroelectric polymer liquid crystal exhibits the Sac phase, resulting in uniaxial orientation.Next, the PET film with the ITO transparent electrodes was placed on the substrate with the top and bottom perpendicular to each other, as shown in Figure 3. Next, a cyanoacrylate instant VC adhesive (trade name, Aron Alpha) was applied at room temperature in an atmosphere of exploding nitrogen gas.
201, manufactured by Toagosei Chemical Industry Co., Ltd. (viscosity: 2 cps) was poured into the voids of the laminate to uniformly permeate the surrounding area. Thereafter, it was placed between glass plates with a thickness of 21 seconds and taken out indoors while applying a load of 200 g/cs2, and left at room temperature for one day to completely harden, yielding a liquid polymer element. When the alignment state of the obtained polymer liquid crystal element was observed using a polarizing microscope, no disorder of alignment was observed over the entire surface. In addition, it is sandwiched between two orthogonal polarizing plates, and ±25V,
When two voltages were applied and the contrast of the amount of transmitted light was compared at the initial stage and after 24 hours of driving, the results were l:5, respectively.
There was no change.

Example 2 In Example 1, the adhesive for sealing was changed to an ultraviolet curable adhesive (product name: RC-852:l, manufactured by Dainippon Ink, viscosity 20 cps), and after penetrating in the same manner, it was left at room temperature. Similarly, without applying any load, ultraviolet rays were irradiated for about 1 hour from a distance of 15 centimeters using a 500 W water-cooled ultra-high pressure mercury lamp to cure the material to obtain a polymer liquid crystal element.

When the alignment state of the obtained polymer liquid crystal element was observed using a polarizing microscope, no disorder of alignment was observed over the entire surface.
, 20 f{z voltages were applied and the contrast of the amount of transmitted light was compared at the initial stage and after 24 hours of driving, and the ratio was 1:5, with no change.

Comparative Example 1 In Example 1, the sealing VC adhesive was an epoxy-based low viscosity adhesive (trade name: RR-16, manufactured by Evotech Co., Ltd.).
After changing the viscosity to 40 cps) and infiltrating it in the same way in a normal room, it was cured at 80°C for 3 hours while applying the same load to obtain a polymer liquid crystal element.

Polarize the obtained polymer liquid crystal element! When I observed it with illW and a mirror, I found that the alignment in the area adjacent to the adhesive was disordered, and that the alignment defect had also propagated inside. [Effects of the Invention] As explained above, since the polymer liquid crystal element of the present invention seals the ferroelectric polymer liquid crystal with a low-temperature curing adhesive, the ferroelectric polymer liquid crystal during sealing Since the occurrence of alignment defects in liquid crystals can be prevented, there is no decrease in contrast, and it has the effect of enabling application to lightweight, large-area display elements with a large amount of transmitted light.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an example of the polymer liquid crystal element of the present invention,
FIG. 2 is a schematic diagram showing another example of the polymer liquid crystal device of the present invention, and FIG. 3 is an explanatory diagram showing the polymer liquid crystal device before sealing the adhesive. 1, la... Substrate 2... Ferroelectric polymer liquid crystal layer 3... Adhesive 4, 4a --- Film with electrodes 5, 5a... Polarizing plate 6, 6a... Striped electrode Figure 1 6 Strife゜Growing Electric God

Claims (2)

[Claims] (1) In a polymer liquid crystal element comprising a ferroelectric polymer liquid crystal sandwiched between a pair of plastic film substrates having electrodes, the ferroelectric polymer liquid crystal is sealed with a low-temperature curing adhesive. A polymer liquid crystal element characterized by: (2) The polymer liquid crystal device according to claim 1, wherein the adhesive is a low-temperature curing type that cures at a temperature equal to or lower than the temperature of the chiral smectic phase of the ferroelectric polymer liquid crystal.