JPH02236524A - Liquid crystal element - Google Patents

Abstract

PURPOSE:To easily obtain a good monodomain by arraying fiber-shaped high polymers which are stretched in a specified direction and using such high polymers as spacers for controlling the gap between substrates. CONSTITUTION:For example, slits 2 in which fibers are passed are disposed near both ends of the substrate 1 and the fiber-shaped high polymers 3 which are stretched after spinning are provided with suitable intervals and are inserted into the slits, then the substrate 1 is pressed onto the line where the fiber-shaped high polymers 3 are arrayed. The spacers to control the gap between the fibers is the stretched fiber-shaped high polymers in such a manner; in addition, the fiber-shaped high polymers are arrayed in the specified direction. The good monodomain is easily obtd. in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an optical modulation element, particularly a display element using liquid crystal. [Prior Art] Optical modulation elements using liquid crystals have been widely known in the past, but recently research into increasing the area of the elements has been attracting attention. Accordingly, there is a need for a technology to create uniform monodomains over a large area.
Up until now, methods for producing monodomains include: - Applying shear stress; - Applying appropriate alignment/restriction force to the substrate surface; - Using spacer edges; - Applying electric and magnetic fields. There is a known method of slow cooling. On the other hand, polymer liquid crystal devices have recently attracted attention as devices that can be easily fabricated into nine layers and are suitable for large-area displays, and among these devices, one that is driven by an electric field is U.S. Pat. No. 42:194: It is known as No. 15. In addition, as other materials that can be driven at high speed, N.A. Plate et al.
1!184) [N. A. Platc etal
．． Polymer Bulletin, 12, 29
9 (1984), a ferroelectric polymer liquid crystal was reported.

In addition, in a polymer liquid crystal element, as an orientation method for producing a monotomine of polymer liquid crystal, a method of applying a stretching treatment (Japanese Unexamined Patent Publication No. 1986-1:171: No. 1, etc.),
A method of applying stress in stages (Japanese Unexamined Patent Application Publication No. 160847/1984 "g") is known.

Furthermore, methods for producing polymer liquid crystal monotomains include a method of imparting uniaxial alignment characteristics to the surfaces of two substrates, similar to the method used for low-molecular liquid crystals, and a method of imparting appropriate alignment characteristics to the side surfaces of the cell. You can also use it.

[Problems to be Solved by the Invention] However, the above conventional method for aligning polymer liquid products has the following problems.

First, is there a good way to perform rapid stretching alignment treatment on polymer liquid crystals that takes advantage of the advantages of polymer liquid crystals?After the device is fabricated, for example, the temperature of the liquid phase is raised to 12 or higher than the isotropic phase. Furthermore, if the orientation is disturbed due to external force being applied to the substrate, it is impossible to completely restore the initial orientation state.

Furthermore, in the method of applying abrasion stress, it is difficult to apply a uniform stress over the entire display area, and it is difficult to obtain uniform monotomains over a large area.

Furthermore, it would be better if the method of subjecting the substrate to orientation treatment could be omitted, considering the number of manufacturing steps for the device.

In addition, in the method of imparting appropriate alignment characteristics to the cell side,
Perfect orientation occurs near the side surfaces, resulting in thousands of monotomines, but the area where monotomines are generated is narrow, and in order to grow these monotomines in an epitaxial manner, it is necessary to slowly cool them with an appropriate temperature gradient. However, it is technically difficult.

The present invention has been made in order to solve the problems of the prior art described above, and its object is to provide a liquid crystal element in which a good monotone can be easily obtained.

[Problems to be Solved by the Invention] and [Operations] That is, the present invention provides a liquid device in which a liquid crystal is sandwiched between a pair of substrates, in which a spacer or a stretched fiber-like spacer is used to control the gap between the two substrates. A liquid crystal element is characterized in that it has a high polymer content and the fifer-like polymers are aligned in a certain direction.

The present invention will be explained in detail below.

The present invention provides a spacer device in which a liquid crystal is sandwiched between a pair of substrates, in which a spacer or stretched fifer-shaped polymer is used to control the gap between the substrates, and the spacer is arranged in a fixed direction. When the liquid material sandwiched between the pair of substrates is slowly cooled from the isotropic phase transition temperature of the liquid crystal for orientation, the fifer-like polymer that is the spacer is attached to the edge of the spacer. By using the fact that the fifer-like polymer has a horizontal alignment force because it is arranged in a certain direction at appropriate intervals within the range where the effect appears, and the effect of the spacer etching appears on the entire surface of the substrate,
Liquid crystals are formed in a uniform monotone manner.

The spacer that can be used in the present invention to control the gap between the substrates uses a stretched fifer-like polymer, and the spacer material is a transparent fifer-like polymer that does not have optical anisotropy. It is more preferable to use a polymer that can be molded into a shape, and the type of polymer can be used without particular limitation. To give a concrete example,
Polyethylene terephthalate 1-Polyacrylonitrile, polyimite, polycarbonate, polyvinyl alcohol, etc. may be mentioned.

Furthermore, a stretched polymer liquid crystal fifer can be used as a spacer material. By stretching the polymeric liquid Fifer, some of the mesogens and substrates are aligned in the length direction of the fiber, so the horizontal alignment regulating force is stronger than that of the above-mentioned polymers, making it easier to create uniaxially oriented monotomains. It is advantageous for When a polymeric liquid crystal is used as the liquid crystal for the display layer, the liquid polymer that can be used as a spacer may be one having a glass transition temperature higher than the operating temperature of the display layer.

Furthermore, the cross-sectional shape of the fifer-like polymer used for the spacer is not particularly limited, and is preferably circular, and its diameter is usually 1 to 50 pm. Preferably 2~
It is desirable for the present invention to be within the range of 20μ. If the diameter of the spacer is large, it will be difficult to achieve a bistable state, and if the spacer is small, it will be difficult to form it into a fiber.

Although the arrangement interval of the spacers of the fifer-like polymer does not necessarily have to be constant, it is preferably constant. Furthermore, the arrangement spacing of phynosu-like polymers is usually 50 to 500 pm. Preferably 100-500gm
It is desirable to arrange spacers within the range of 1. If the distance between the spacers exceeds 500H, the alignment effect of the spacer engine will be weakened, making it impossible to produce a uniform monotomain, and if the distance is less than 50pm, it may adversely affect the switching characteristics of the liquid crystal. A preferred method for producing the fifer-like polymer is a conventional polymer spinning method, such as a melt spinning method, a solution spinning method, and the like.

Next, as a method for arranging fifer-like polymers spun by the above method in a fixed direction on a substrate, for example, the first
As shown in the figure, after slits 2 through which fibers are passed are placed near both ends of the substrate l, fiber-like polymers 3 that have been spun and drawn are passed through the slits at appropriate intervals.
One possible method is to press the substrate 1 onto the line on which the fifer-like polymers 3 are arranged, but the method is not limited to this method.

Furthermore, after arranging fifer-like polymers on a substrate using the method described above, in order to form a cell, in addition to the usual bonding method, if polymer liquid crystal is used, the polymer liquid crystal is melted. Alternatively, it can be applied directly in a liquid crystal state, or it can be applied in a soluble solvent using a Harcoater or roll coater, and then the substrate can be heated to dry the solvent, or a polymeric liquid crystal film adjusted to an appropriate thickness can be coated on the substrate. After forming the display layer on the substrate by directly placing it on the substrate, the upper substrate is placed on the substrate, and the upper substrate is pressed while being maintained at the isotropic phase transition temperature of the polymer liquid crystal, which is the surface layer, to achieve chiral smecting. All you have to do is slowly cool it to a temperature that shows a phase. When slowly cooling, an electric field or a magnetic field may be applied auxiliary. In addition, in the wood invention, where an appropriate sealant may be applied to the substrate to enhance the adhesion effect if necessary, various polymer films can be used in addition to glass as materials that can be used as the substrate. It's coming. Specific examples of polymer films include polyethylene film, polypropylene film, polyester film, polyvinyl alcohol film, polyamide film, and polycarbonate film. Boliimito film. Examples include polyvinyl chloride film, polystyrene film, polytetrafluoroethylene film, polyacrylic film, and polyvinyl fluoride film.

By using these substrate materials, flexible display elements can be formed. In the present invention, when a display on a curved surface is formed using a flexible substrate material as described above, by using a fibrous polymer spacer, the contact area between the substrate and the spacer is increased, and a uniform gap is created. There is also the advantage of maintaining

Examples of liquid crystals sandwiched between substrates that can be used in the present invention include commonly used nematic liquid crystals with Δε>0, ferroelectric liquid crystals, and the like.

Among other liquid crystal materials that can be used, it is preferable to use polymeric liquid materials as materials for large-screen display elements.

The polymeric liquid crystal material is a nematic liquid crystal with Δε>0, specifically, a nematic liquid crystal having the following structural formula (A). The polymer liquid crystal represented by (B) can be exemplified, but is not limited to these. In addition, ferroelectric polymer liquid products are the most preferred material to use in terms of their high-speed response. (A) CH, (B) The ferroelectric polymer liquid crystal that can be used in the present invention preferably has a chiral smectic phase, more preferably a Sac" phase, SmH" phase, S* It is desirable to have I” phase, SmJ” phase, and SmG” phase.

In addition, strong electrostatic polymer liquid crystals include main chain type, side chain type,
Those having a main chain one-side chain type structure are used, and main chain type ferroelectric polymer liquid crystals include polyester, polyether, and polyazomethine types. Volithioester type. Borithioether type, polysiloxane type, boriamite type,
It is also possible to use polyimide, etc. Polymethacrylate is a side chain type ferroelectric polymer liquid crystal. Polyacrylic. Polychloroacrylic, polyether, etc. can be used. The above-mentioned main chain type, side chain type, main chain single side chain type ferroelectric liquid crystal compound may be used alone, or 28 or more of the same or different types of polymer liquid crystal compounds may be used. However, a copolymerized material may also be used.

Next, specific examples of ferroelectric polymer liquid crystals that can be used in the present invention are shown below, but the invention is not limited to these. −+−C H 2− C Hh− ? 2) +C11■-C}15 m≧5, n=4~[8 f=1~2, k=1~2. j=0 or l, n=4 to 18, m≧5 f=1 to 2, k=1 to 2, n=4 to l8, m≧5 −+C If 2- C tl}, −k=1 to 2, k=1-2, j=Q or 1, n=4-18. m≧5! = 1-2, k=1-2, j=0 or l, n=4-18, m≧5 j=o or l, m≧5 (■2=2-l5. x+y=1) x=0 .1 ~l. 0, m=4~12, n≧
3. Optically active polymer liquid crystals that can exhibit ferroelectricity by blending or the like 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 weight liquid crystals, compatibility must be considered. The ratio of low molecular weight liquid crystal to be blended is 1~
90% by weight, preferably in the range of 5 to 50% by weight. (x+y=l, s.=2~15) (!3) (l4) (x+y=1, @*:2~Is) (x+y
=1) (x+y=l, m*=2~Is) (l2) (1.=1~5) (x+y=1) (ms=1~3, j?=1~20) (+7) (l5χ0 ~5) (m,=o~5) (1!l) (vs=0~5) (s5=O~5) [Example] Hereinafter, the present invention will be described in more detail by showing examples.

Example 1 Polyethylene terephthalate was stretched and molded into a fifer shape with a diameter of 5H on a polyester film on which a striped transparent electrode was attached, and was arranged in a 300 l 1 bit pattern. Next, the polyester film coated with striped transparent electrodes was glued together with a sealant so that the stripes were perpendicular to each other. Next, a polymeric liquid product represented by the following structural formula (2l) was injected into a capillary at a temperature of 100°C in a reduced pressure atmosphere from a place that had not been coated with a sealant on the day the liquid crystal was injected. Created a child.

The liquid crystal slip prepared as described above was placed on a transparent heating element made of ITO thin film or stripes so that the stripes of the transparent heating element matched the alignment direction of the polyethylene terephthalate fibers, and the ITO was energized. The liquid crystal phase was maintained in an isotropic state (90° C.). Next, the current applied to the striped electrodes was adjusted to slowly cool the entire cell to room temperature. When the orientation state was observed using a polarizing microscope, it was found that a good monotomine with no defects was obtained.

-I'-C I{ 2- C H +T was also obtained as a good tI7- monotomine with no orientational defects.

Example 2.3 Using the same substrate and fifer material as used in Example 1, the size was 200 mm long x 300 mm wide and the half diameter was 300 mm.
A curved display cell was created by attaching a substrate to the side surface of a m@ cylinder, and the following structural formula (22) and structural formula (
23) A liquid device was prepared by capillary injection of liquid crystals represented by the following formulas at a temperature higher than the isotropic phase transition temperature of each liquid crystal.

Furthermore, when each liquid crystal element was slowly cooled to room temperature at a cooling rate of 2°C/sin, the curved surface of each liquid crystal element was obtained using the following structural formula (
24) A stretched fifer with a diameter of 5 mm made of main button type polymer liquid crystal expressed as a spacer,
They were arranged on the substrate at a pitch of 100 g. Thereafter, a liquid crystal cell was produced in the same manner as in Example 1. Next, a polymer liquid crystal represented by the following structural formula (25) was injected into a capillary under a reduced pressure atmosphere to prepare a liquid crystal element. When this liquid element was slowly cooled to room temperature in the same manner as in Example 1, a good monotomain with no defects was obtained.

CH, Example 5 A liquid crystal element was prepared using the same configuration as used in Example 2, with a spacer diameter of 10 μl and a pitch of 500 μl.

When performing slow cooling in the same manner as in Example 1, the cell was placed on a planar heater and the temperature of the heater was set to: g! When the liquid crystal element was slowly cooled while applying an AC voltage with an effective value of 20 V and a frequency of IKIIz to the upper and lower electrodes of the liquid crystal element, a good monotomain was also obtained.

[Effects of the Invention] As explained above, according to the present invention, by arranging stretched fifer-like polymers in a certain direction and using them as spacers to control the gap between substrates, it is possible to easily form a good monotomain. You can get it.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an example of a method for arranging fiber-like polymers in a fixed direction on a substrate. 1... Substrate 2... Slit 3... Fiber-like polymer

Claims (5)

[Claims] (1) In a liquid crystal element in which a liquid crystal is sandwiched between a pair of substrates, the spacer for controlling the gap between the substrates is a stretched fibrous polymer, and the fibrous polymer is arranged in a fixed direction. A liquid crystal element characterized by: (2) The liquid crystal device according to claim 1, wherein the stretched fibrous polymer is a polymeric liquid crystal. (3) The liquid crystal element according to claim 1, wherein the liquid crystal is a polymer liquid crystal. (4) The liquid crystal element according to claim 1, wherein the liquid crystal is a ferroelectric polymer liquid crystal having a chiral smectic phase. (5) The arrangement interval of the fibrous polymer is 50 to 50.
The liquid crystal element according to claim 1 or 2, which has a thickness of 0 μm.