JPH0460519A - Liquid crystal element and production thereof - Google Patents

Abstract

PURPOSE:To improve a contrast ratio and threshold value characteristic, etc., by crimping a liquid crystal material between a pair of substrates with electrodes formed by subjecting the surfaces on the electrode sides facing each other to an irradiation treatment with UV rays. CONSTITUTION:This element consists of a pair of the substrates subjected to the irradiation treatment with the UV rays on the surfaces on the electrode sides of the substrates with the electrodes and the liquid crystal material crimped between these substrates. The irradiating treatment with UV rays in executed by irradiating the surface of the electrode side of the substrate having electrode with UV rays. The surfaces of the substrates with the electrodes are cleaned and activated by such irradiation treatment with the UV rays. Namely, the stains of the org. matter, etc., stuck to the electrode surfaces are removed and cleaned by the UV light in the parts having the electrodes. The electrode surfaces are cleaned and the molecular structure of the substrate surfaces is changed and the surfaces are activated by the energy of the UV light in the parts where the electrodes are removed by etching, etc., and the substrates are exposed. The contrast ratio, threshold value characteristics, etc., are improved in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a liquid crystal element used in the electrical and electronic industry fields. The present invention also relates to a method for manufacturing a liquid crystal element.

[Conventional technology]

In order to perform liquid crystal display using a liquid crystal element, it is necessary that liquid crystal molecules are oriented. In conventional liquid crystal devices, in order to align liquid crystal molecules in the desired state, a resin film such as polyimide is placed on the electrode surface of a substrate with electrodes that sandwich the liquid crystal, and this is widely used by rubbing treatment. . Furthermore, in order to improve the orientation of liquid crystal molecules, the steepness characteristics of the liquid crystal element with respect to electric field changes, the viewing angle characteristics, etc., a technique is known in which the resin film is irradiated with ultraviolet light (Japanese Unexamined Patent Application Publication No. 1983-1992).
-113213).

However, in these conventional techniques, an alignment film such as a resin film is essential on the electrode surface of the electrode-equipped substrate, and the quality of the alignment film determines the quality of the alignment of liquid crystal molecules. Therefore, in order to obtain a good alignment state of liquid crystal molecules, processes such as forming an alignment film and rubbing treatment cannot be avoided, and these processes are the cause of a decrease in the yield of liquid crystal elements. .

On the other hand, in order to obtain good alignment of liquid crystal molecules without using an alignment film or rubbing treatment, a method has been proposed in which the liquid crystal element is subjected to bending deformation treatment and the liquid crystal molecules are aligned by shearing (Japanese Patent Laid-Open No. 2-10322). However, even with this technology, the condition of the electrode-side surface of the electrode-equipped substrate that the liquid crystal is in direct contact with affects the final alignment of the liquid crystal molecules, which in turn affects the contrast ratio, threshold characteristics, etc. of the liquid crystal element. do. Therefore, there is a demand for a liquid crystal element in which the surface of the electrode-attached substrate on the electrode side is in good condition and has excellent contrast ratio, threshold characteristics, and the like.

[Problem to be solved by the invention]

The present invention has good interfacial interaction between liquid crystal molecules and a substrate with electrodes, excellent orientation of liquid crystal molecules, and a high contrast ratio.
The purpose is to provide a liquid crystal element with good threshold characteristics and the like.

Another object of the present invention is to provide a method for manufacturing a liquid crystal element that can easily and efficiently manufacture the liquid crystal element as described above.

[Means for Solving the Problems] As a result of extensive research in order to solve the above problems, the present inventors have developed a liquid crystal using a substrate with electrodes of a liquid crystal element whose surface on the electrode side is treated with ultraviolet light irradiation. The inventors have discovered that the object can be achieved by using a device, and have completed the present invention based on this knowledge.

That is, the present invention provides a liquid crystal element in which a liquid crystal material is sandwiched between a pair of electrode-attached substrates whose surfaces on opposing electrode sides have been treated with ultraviolet light irradiation.

The liquid crystal element of the present invention consists of a pair of substrates with electrodes and a liquid crystal material sandwiched between them.

Examples of the substrate for the electrode-attached substrate include glass and flexible plastic substrates. As the flexible plastic substrate, for example, polyether sulfone (PES), polyethylene terephthalate (PET), polycarbonate (PC), etc. are preferably used.

The electrode is preferably a transparent electrode formed on the substrate by a method such as vapor deposition. Specifically, Inzos 5n
OzWI etc. are mentioned. The electrodes may be patterned by a method such as etching. When the electrode is patterned, the substrate is exposed where the electrode is removed.

In the liquid crystal element of the present invention, the electrode-side surface of the electrode-attached substrate is subjected to ultraviolet light irradiation treatment.

The ultraviolet light irradiation treatment is performed by irradiating the electrode-side surface of the electrode-equipped substrate with ultraviolet light. The wavelength of the ultraviolet light to be irradiated is 1
80-400 nm is preferred. Ultraviolet light with a longer wavelength than this may reduce the treatment effect. Furthermore, for ultraviolet light with a shorter wavelength, the window of the light source may require a special glass material, or gas replacement or evacuation may be necessary to avoid absorption of ultraviolet light by oxygen in the air. Therefore, the cost is high and it is not practical.

The output of the ultraviolet light is preferably about 50 to 400W.

Moreover, the irradiation time of ultraviolet light is preferably about 30 to 180 seconds. If the output or irradiation time is less than this, the effect of irradiation may be weakened, and if it is more than this, there is a risk of damaging the substrate and the like.

It is thought that the surface of the electrode-attached substrate is cleaned and activated by such ultraviolet light irradiation treatment. In other words, in the part where the electrode is, dirt such as organic matter adhering to the electrode surface is removed by ultraviolet light, making it clean, and in the part where the electrode is removed by etching etc. and the substrate is exposed, the surface of the board is It is thought that the molecular structure of the substrate surface changes and becomes activated due to the energy of the ultraviolet light. These effects improve the interfacial interaction between the liquid crystal material and the substrate with electrodes, and improve the contrast ratio, threshold characteristics, etc. of the liquid crystal element.

The liquid crystal element of the present invention is formed by sandwiching a liquid crystal material between a pair of electrode-attached substrates that have been subjected to the above-mentioned ultraviolet light irradiation treatment. At this time, the pair of electrode-equipped substrates are arranged with the electrode sides facing inside.

Any known liquid crystal material can be used as the sandwiched liquid crystal material. Among these, ferroelectric liquid crystal materials are preferred. In particular, a liquid crystal material made of a ferroelectric polymer liquid crystal or a composition thereof is preferred. When such a liquid crystal material is used, liquid crystal molecules can be easily aligned by a method using shear force such as bending deformation without using a rubbing method.

Specifically, suitable ferroelectric polymer liquid crystals include the following.

(1) Ferroelectric polymer liquid crystal 1h with polyacrylate main chain (J, C. Dubois et al., Mo1. Cry
st, Liq, Cryst, 1986, 13
7. 349) (3) Ferroelectric polymer liquid crystal with polychloroacrylate beads (J, C. Dubois et al., Mo1. Crys
t, Liq, Cryst, + 1986, 137
．． 349) (4) Ferroelectric polymer liquid crystal having a polyoxysilane main chain (2) Ferroelectric polymer liquid crystal having a polymethacrylate main chain (JP-A-63-264629) (5) Polysiloxane main chain (6) Ferroelectric polymer liquid crystal C0° having a polyester main chain (Japanese Unexamined Patent Application Publication No. 1983-1999) -113424) (Japanese Unexamined Patent Publication No. 113424) (R, Zentel et al., Liq, Cryst,
1987.2.83) The side chain (mesogen) moiety of each polymeric liquid crystal has various skeletons known in low-molecular liquid crystals (e.g., biphenyl skeleton, phenylbenzoate skeleton, biphenylbenzoate skeleton, phenyl-4-phenyl skeleton). Henshade skeleton). The benzene ring in each skeleton is, for example, a pyrimidine ring,
It may be substituted with a pyridine ring, pyridazine ring, cyclohexane ring, dioxoborinane ring, etc. (and may have a halogen group such as fluorine or chlorine.
Examples of optically active groups include 1-methylalkyl group, 2-fluoroalkyl group, 2-chloroalkyl group, 2-chloro-3-methylalkyl group, 1-trifluoromethylalkyl group, 1-alkoxycarbonylethyl group, It may be substituted with a 2-alkoxy-1-methylethyl group, a 2-alcoquinepropyl group, a 2-chloro-1-methylalkyl group, a 2-alcokynecarbonyl-1-trifluoromethylpropyl group, or the like. Further, the length of the spacer may vary within the range of 1 to 30 as long as it exhibits ferroelectricity.

In addition, the composition of the ferroelectric polymer liquid crystal may be a mixture of the above-mentioned ferroelectric polymer liquid crystal with a polymer substance such as a thermoplastic resin, a cross-linked resin, or a non-ferroelectric polymer liquid crystal. can be mentioned. These polymeric substances can be used alone or 211! The above may be mixed, or a copolymer may also be used. Further, as the composition of the ferroelectric polymer liquid crystal, a composition of the above-mentioned ferroelectric polymer liquid crystal and a low-molecular compound, or a composition of the above-mentioned ferroelectric polymer liquid crystal and a mixture of a high-molecular substance and a low-molecular compound You can also use objects.

As the low molecular compound, either a liquid crystal compound or a non-liquid crystal compound can be used. Mixing low molecular weight compounds may be effective in improving the liquid crystal temperature range and response time.

The liquid crystal element of the present invention having the above configuration can be suitably manufactured by the following method.

That is, a step of irradiating the electrode-side surface of a substrate with an electrode with ultraviolet light, a step of applying a liquid crystal material to the electrode-side surface irradiated with ultraviolet light to form a liquid crystal layer, and a step of applying an electrode on the formed liquid crystal layer. A liquid crystal characterized by comprising the steps of stacking substrates with electrodes whose side surfaces are irradiated with ultraviolet light so that the liquid crystal layer and the electrode side surface are in contact with each other, and orienting the liquid crystal material of the obtained stacked product. Manufactured by an element manufacturing method.

First, in the ultraviolet light irradiation step, ultraviolet light is irradiated onto the electrode-side surface of the electrode-attached substrate.

The ultraviolet light to be irradiated is as described above.

Next, in the step of forming a liquid crystal layer, a liquid crystal material is applied to the surface of the electrode irradiated with ultraviolet light to form a liquid crystal layer.

The method of applying the liquid crystal material is to increase the fluidity by dissolving the liquid crystal material in a solvent or heating it, and then to apply it by microgravure method, direct gravure method, etc.
A successful method is to coat the electrode-side surface of the electrode-equipped substrate with a uniform film thickness. An impregnating coating method in which an impregnated member is impregnated with a liquid crystal material with increased fluidity, and the impregnated member is pressed against the electrode-side surface of the electrode-equipped substrate and applied while moving.
-10322) is also suitable.

Next, in the substrate stacking step, a substrate with electrodes whose electrode-side surface has been irradiated with ultraviolet light is stacked on top of the formed liquid crystal layer so that the liquid crystal layer and the electrode-side surface are in contact with each other.

As the substrate to be superimposed, a substrate with electrodes that has been irradiated with ultraviolet light is used, similar to the one that was coated with a liquid crystal material in the previous step.

Then, the upper and lower substrates are stacked to prevent air bubbles from entering between the stacked substrates and the liquid crystal layer, and the liquid crystal layer is sandwiched between the upper and lower substrates to have a uniform thickness. At this time, it is preferable to heat the substrates to be stacked.

Furthermore, in the liquid crystal material alignment treatment step, the obtained superimposed liquid crystal material is subjected to alignment treatment to orient the liquid crystal molecules.

As a method for aligning liquid crystal materials, the stacked substrates are heated, and the upper and lower substrates are sheared at a temperature lower than the phase transition point between the isotropic phase and the liquid crystal phase to align the liquid crystal material. A method of orienting molecules (described in JP-A-110322) is suitable.

The above steps can be carried out continuously if a long flexible substrate with electrodes is used, which is preferable as it further improves the productivity of the liquid crystal element.

〔Example〕

Hereinafter, the present invention will be explained in detail based on Examples, but the present invention is not limited thereto.

Example 1 As a substrate with electrodes, an ITO transparent electrode (
0.2 cij, thickness: 1,000 layers) was used.

Figure 1 shows the shapes of the substrate and electrodes used.

An ITO transparent electrode 2 was formed on a substrate 1 by vapor deposition in a shape having a circular part and a lead line part 3.

The electrode-side surface of this electrode-attached substrate was irradiated with ultraviolet light for 2 minutes using a UV cleaner manufactured by Nippon Battery. The main ultraviolet light emission peaks of this UV cleaner are 184.9 and 2.
53.7 nm, and the total emission intensity was 120W.

The substrate with electrodes that had been irradiated with ultraviolet light was taken out of the UV cleaner, and a ferroelectric polymer liquid crystal having the following repeating units was coated on the electrode-side surface by impregnation coating to form a liquid crystal layer with a thickness of approximately 1 μm. .

CH.

Mn=8700 (Iso: Tokichi phase, SmA: Smekchi Nku A
phase, SmC": chiral smectinoku C phase, glassy phase] Next, after heating the liquid crystal material to 100"C, the formed liquid crystal layer was exposed to two ultraviolet rays in the same manner as the electrode-attached substrate described above. The counter substrates that had been irradiated with the above were stacked together so that the liquid crystal layer and the surface on the electrode side were in contact with each other.

Thereafter, while slowly cooling the obtained stacked product at a rate of 1°C/min, the stacked product was heated to 68 to 60°C to 0.
．． The liquid crystal material was aligned by applying shear deformation of 5 m 10 times to align the liquid crystal molecules.

Furthermore, the stacked product was cooled to room temperature, and the periphery of the substrate was sealed with an instant adhesive (Hi-Super, manufactured by Cemedine) to obtain a liquid crystal element. Furthermore, a lead wire was soldered to the lead wire of the transparent electrode.

FIG. 2 is a cross-sectional view of the obtained liquid crystal element.

1 is a substrate, 2 is an ITO transparent electrode, 4 is a liquid crystal material, 5 is an adhesive, and 6 is a lead wire.

The contrast ratio of the obtained liquid crystal element was measured.

FIG. 3 is a schematic diagram showing the measurement system used.

The liquid crystal element 7 is placed in a constant temperature bath 8, one lead wire 6 drawn out from the liquid crystal element 7 is grounded, and the other lead wire 6 is connected to the output terminal of an arbitrary function generator 11 connected to a computer 10 via an amplifier 12. I connected it. In addition, the liquid crystal element 7
A polarizing microscope 1 installed above the liquid crystal element 7 measures the amount of light emitted from a light source 9 installed at the bottom of the liquid crystal element 7 and transmits the light through the liquid crystal element 7.
3 and recorded as an electrical signal by a photomultiplier tube 14 by a waveform recorder 15.

Using such a measurement system, a DC voltage of ±IOV was applied between the electrodes of the liquid crystal element, as shown in FIG. 4(a).

At this time, as shown in FIG. 4(b), the ratio C of the amount of transmitted light in the bright state (IoN) and the amount of transmitted light in the dark state (IOFF)
v was measured as the contrast ratio when voltage was applied.

CV = I ON/I 0FF The larger the CvO value, the better the liquid crystal element is.

Next, as shown in FIG. 5(a), a DC voltage of +10 cm was applied for 1 second between the electrodes of the liquid crystal element, and then the voltage was reduced to 0 cm.
The amount of transmitted light after 5 seconds (1ON) in the case of -
The ratio Cm to the amount of transmitted light (I OFF ) after 5 seconds when the voltage was set to OV after applying a DC voltage of 10 μ for 1 second was measured as the memory contrast ratio (5th
Figure (b)).

Cm-1 ON/I OFF The larger the CmO value, the better the liquid crystal element.

Next, we measured the threshold characteristics of the liquid crystal element. The measurement system was the same as that shown in Figure 3. Memory time versus Vw when a voltage with the waveform (pulse width 10m5) shown in Figure 6(a) is applied between the electrodes of the liquid crystal element and the write voltage Vw is gradually increased from 0 to Vr (reset voltage). amount of transmitted light 1
m was recorded (Figure 6(b)). As shown in FIG. 6(C), when Im is viewed as a function of Vw, the write voltage V is required for the amount of transmitted light to reach 10% of the total. and the write voltage V required for the amount of transmitted light to reach 90% of the total,
. Karae, steepness T −V q. /V. was calculated and the threshold characteristics were evaluated. The closer T is to 1, the better the threshold characteristics of the liquid crystal element.

The results are shown in Table 1.

Comparative Example 1 A liquid crystal element was manufactured in the same manner as in Example 1, except that the surface of the substrate was covered with aluminum foil so that the ultraviolet light did not reach the electrode-side surface of the substrate when irradiating the electrode-equipped substrate with ultraviolet light.

The properties of the obtained liquid crystal element were evaluated in the same manner as in Example 1. The results are shown in Table 1.

Example 2 A liquid crystal element was manufactured in the same manner as in Example 1 except that a polyethylene terephthalate (PET) substrate (100 μm thick, CELEC-K manufactured by Daicel Chemical Industries, Ltd.) was used as the substrate with electrodes.

The properties of the obtained liquid crystal element were evaluated in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 2 A liquid crystal element was manufactured in the same manner as in Example 2, except that the surface of the substrate was covered with aluminum foil so that the ultraviolet light did not reach the electrode-side surface of the substrate during irradiation of the electrode-attached substrate with ultraviolet light.

The properties of the obtained liquid crystal element were evaluated in the same manner as in Example 1. The results are shown in Table 1.

Example 3 Polyether sulfone (PE) was used as the substrate for the electrode-attached substrate.
S) Substrate (thickness 100μm, manufactured by Jushimaheklite FS)
A liquid crystal element was manufactured in the same manner as in Example 1 except that T-1351) was used.

The properties of the obtained liquid crystal element were evaluated in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 3 A liquid crystal element was manufactured in the same manner as in Example 3, except that the surface of the substrate was covered with aluminum foil so that the ultraviolet light did not reach the electrode-side surface of the substrate when irradiating the electrode-equipped substrate with ultraviolet light.

The properties of the obtained liquid crystal element were evaluated in the same manner as in Example 1. The results are shown in Table 1.

As shown in Table 1, in all cases, the results of the examples were superior to those of the comparative examples, confirming the effect of ultraviolet light irradiation.

C Effects of the Invention] The liquid crystal element of the present invention has good interfacial interaction between the liquid crystal molecules and the substrate, excellent orientation of the liquid crystal molecules, and good contrast ratio, threshold characteristics, and the like.

Further, according to the method for manufacturing a liquid crystal element of the present invention, the above liquid crystal element can be manufactured easily and efficiently.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing the shapes of the substrate and electrodes used in the example. FIG. 2 is a cross-sectional view of the liquid crystal element obtained in Example I. FIG. 3 is a schematic diagram showing a measurement system used to measure the characteristics of a liquid crystal element in Example I. 4(a), FIG. 5(a), and FIG. 6<a) are graphs showing the voltage applied between the electrodes of the liquid crystal element in Example 1. The horizontal axis shows time, and the vertical axis shows applied voltage. FIG. 4(b), FIG. 5(b), and FIG. 6(b) are graphs showing the amount of transmitted light of the liquid crystal element of Example 1. The horizontal axis shows time, and the vertical axis shows the amount of transmitted light. FIG. 6(C) is a graph showing the relationship between the write voltage and the amount of transmitted light. The horizontal axis shows the write voltage (VW), and the vertical axis shows the amount of transmitted light (Im). Substrate lead wire Adhesive Liquid crystal element Light source Arbitrary function generator Polarizing microscope Waveform recorder ITO Transparent electrode Liquid crystal material Lead wire Constant temperature bath Computer amplifier Photomultiplier tube Polarizing plate No. 1114Ln^' 1ζ6-生11 16 Requester Chichigaki pressure voltage

Claims (1)

[Claims] 1. A liquid crystal element in which a liquid crystal material is sandwiched between a pair of electrode-attached substrates whose surfaces on opposing electrode sides have been treated with ultraviolet light irradiation. 2. A step of irradiating the electrode-side surface of the electrode-equipped substrate with ultraviolet light, a step of applying a liquid crystal material to the electrode-side surface irradiated with ultraviolet light to form a liquid crystal layer, and applying an electrode on the formed liquid crystal layer. It is characterized by comprising the steps of stacking electrode-equipped substrates whose side surfaces are irradiated with ultraviolet light so that the liquid crystal layer and the electrode-side surface are in contact with each other, and aligning the liquid crystal material of the obtained stacked product. A method of manufacturing a liquid crystal element.