JPH02180966A - Ferroelectric polymeric liquid crystal composition and ferroelectric polymeric liquid crystal display element - Google Patents

Abstract

PURPOSE:To make it possible to form a quest-host type ferroelectric polymeric liquid crystal composition amenable to film formation and uniaxial orientation by mixing a polymeric liquid crystal having a ferroelectric liquid crystal phase with a dichroic colorant. CONSTITUTION:This ferroelectric polymeric liquid crystal composition comprises a polymeric liquid crystal having a liquid crystal phase showing ferroelectricity and a dichroic colorant. As the liquid crystal composition, one having a glass transition point is good or one containing a ferroelectric low-molecular liquid crystal is desirable. It is desirable that the ferroelectric polymeric liquid crystal has a chiral smectic phase. For example, a ferroelectric polymeric liquid crystal display element is formed by using the above ferroelectric polymeric liquid crystal composition. Said element is constructed in such a way that the ferroelectric polymeric liquid crystal composition in a stretched and oriented state is held between a pair of electrodes 3 and 3 (display layer 5), a polarizing plate 1 having an axis of vibration normally crossing the direction of orientation of the liquid crystal composition is provided, and the state of the element is discriminated through the polarizing plate 1.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a ferroelectric polymer liquid crystal composition containing a dichroic dye and an optical modulation element using the same, particularly a guest-host type color display element. Regarding.

[Prior Art] Conventionally, liquid crystal display elements display images or information by configuring a scanning electrode group and a signal electrode group in a matrix, and filling a liquid crystal compound between the electrodes to form a large number of pixels. well known. The driving method for this display element is time-division driving, in which an address signal is selectively and periodically applied to two scanning electrode groups in sequence, and a predetermined information signal is selectively applied in parallel to the signal electrode group in synchronization with the address signal. It has been adopted.

Most of these were put to practical use, for example, “Applied Physics Letters”.
Physics Letters'') Volume 18, No. 4
issue (February 15, 1971), pp. 127-128, co-authored by M. Chadt (J, 5chadt) and L. Helfrich (“Voltage Dependant Optical”).
Activity of a Twisted Nematic Liquid Crystal n (“VoltageD
pendent 0ptical Activity
of a TwistedNematic 1iqu
It was a twisted nematic type liquid crystal shown in "TD Crystal".

In recent years, both Clark and Lagerwall have proposed the use of bistable liquid crystal elements as an improved version of conventional liquid crystal elements (Japanese Unexamined Patent Publication No. 107216/1983, U.S. Pat. No. 4367924, etc.), and as a liquid crystal having bistability, chiral smectic C phase (Ss+'
C) or a ferroelectric liquid crystal having an H phase (Sm"H). In these states, in response to an applied electric field, either a first optically stable state or a second optically stable state is used. It has the property of maintaining that state when no electric field is applied, that is, it has stability, and is expected to be widely used in fields such as high-speed and memory-type display devices that respond quickly to changes in electric field. ing.

Furthermore, due to its excellent viewing angle characteristics, it has a large capacity and
It is considered suitable as a material for large-area displays. However, when actually forming a liquid crystal cell, it is difficult to monodomain over a wide area, and there are technical problems in producing a large screen display element.

To solve this problem, it has been reported that a ferroelectric smectic liquid crystal monodomain can be created by an epitaxial method using interfacial energy. (U.S. Pat. No. 4,561,726) However, the monodomains obtained in this way are not inherently stable and are easily converted into multidomains by pressure or thermal stimulation, making it difficult to increase the area.

On the other hand, polymer liquid crystal elements have been proposed as devices that are easy to fabricate and suitable for large-area displays. A device driven by an electric field is known, such as US Pat. No. 4,239,435.

Further, British Patent No. 2146787 is known as a method for addressing using heat, typically laser light, and Japanese Patent Application Publication No. 4-14114 is known for addressing using a thermal head or the like.

Products using these polymer liquid crystal elements are either suitable for large-area, high-definition displays, or have slow response speeds that make them unsuitable for applications that involve moving images or high-speed rewriting.

Various studies have been made to eliminate the above drawbacks. One of them is N. Brate et al., "Polymer Bulletin J, p. 12, 299, (1984)
[N, A, Plate etal, Polymer
Bulletin, 12°299 (1984)], a ferroelectric polymer liquid crystal was reported. This ferroelectric polymer liquid crystal is easy to form into devices such as film formation and is suitable for large-area displays, and is expected to be put into practical use as it has significantly improved response speed compared to conventional polymer liquid crystals. .

A guest-host type display method is known as a color display method using ferroelectric liquid crystal. [Nakano et al. “Ninth International Liquid Crystal Conference J 1982 (F.

Nakano et a[,,9th Int.
1. iq, Crysl Conf, J
-2P (1982), Kondo, gills, isogai,
Muko et al., “Japanese Journal of Applied Physics,” vol. 24, p. 1389, 1985.
Year (K, niondo, S, Era, M, lsoga
i and A, Mukoh, Jpn.

J. Appl, Phys., 24 (1985)
1ko89), Isogaikonto Kitamura Muko
Nagae Kawakami et al., “°86 International Display Research Conference”, vol. 472,
1986 (M. Isogai, K. Kond.
o, T, KiLamura, A, Mukoh.

Y, Nagae and Il, Kawakami
, '86 1nt, DisplayRes,
Conf, 12-5 (1986) 472. )
] This method has the feature that the device configuration is simple because it is necessary to use only one polarizer.

A method of recording by adding a dye to a polymeric liquid crystal is disclosed in, for example, Japanese Patent Application Laid-open No. 59-35989.

Can you give an example of JP-A-60-179294?
None of them were guest-host type devices that utilized polarization inversion of ferroelectric polymer liquid crystals.

[Problems to be Solved by the Invention] However, since color display elements using conventional guest-host type ferroelectric liquid crystals are low-molecular ferroelectric liquid crystal elements, alignment treatment of the substrate is required. However, the number of cell manufacturing steps is increased, and when multicolor display is performed by laminating layers, the device structure becomes complicated, and the viewing angle characteristics worsen due to the increased cell thickness.

The present invention was made in order to improve the drawbacks of the conventional technology, and contains a polymeric liquid crystal having a liquid crystal phase exhibiting ferroelectricity and a dichroic dye, and is capable of forming a film and uniaxially aligning it. A guest-host type ferroelectric polymer liquid crystal composition that is easy to control and has good viewing angle characteristics using the same.
The object of the present invention is to provide a guest-host type ferroelectric polymer liquid crystal display element capable of displaying multiple colors without requiring alignment treatment on a substrate.

[Means for Solving the Problems 1] The present invention provides a ferroelectric polymer liquid crystal composition comprising a polymer liquid crystal having a liquid crystal phase exhibiting ferroelectric properties and a dichroic dye. It is a thing.

The present invention also provides a ferroelectric polymer liquid crystal composition containing a dichroic dye and a polymer liquid crystal having a liquid crystal phase exhibiting ferroelectricity, which is stretched and oriented and held between a pair of electrodes. and a polarizing plate having a vibration axis perpendicular to the stretching direction of the ferroelectric polymer liquid crystal composition, and a display state is identified through the polarizing plate. .

Furthermore, the present invention provides an element comprising a ferroelectric polymer liquid crystal composition containing a dichroic dye and a polymer liquid crystal having a ferroelectric liquid crystal phase between a pair of electrodes in a stretched and oriented manner. A polarizing plate formed by laminating two or more layers with the stretching direction of the ferroelectric polymer liquid crystal composition aligned in the same direction, and having a vibration axis perpendicular to the stretching direction of the ferroelectric polymer liquid crystal composition. A ferroelectric polymer liquid crystal display element is characterized in that multicolor display states can be identified by different absorption bands of dichroic dyes contained in each element layer through the polarizing plate. .

The present invention will be explained in detail below.

The present invention provides that a ferroelectric polymer liquid crystal composition containing a polymer liquid crystal having a liquid crystal phase exhibiting ferroelectricity and a dichroic dye forms a film, and that after forming the film, stretching and alignment are performed. What is applied is a guest of polymer liquid crystal and dichroic dye.
It is characterized by the fact that uniaxial alignment can be easily obtained in the host type composition, and that it is in the form of a polymeric liquid crystal or film, and that it can be made into an element or a cell without having a particularly sealed cell structure. be.

In the present invention, a ferroelectric polymer liquid crystal composition (hereinafter referred to as a polymer liquid crystal composition) is a polymer liquid crystal having a liquid crystal phase exhibiting ferroelectricity (hereinafter referred to as a ferroelectric polymer liquid crystal). Preference is given to using mixtures of molecular liquid crystals.

The ferroelectric polymer liquid crystal preferably has a chiral smectic phase, more preferably S-C.
1′ phase, S Otori H” phase, S Otori■1 phase, S Zen J” phase, S Oboro G
``It is something that has phases.

Also, as a ferroelectric polymer liquid crystal, main chain type is used.

Those having a side chain type or main chain-side chain type structure are used, and main chain type ferroelectric polymer liquid crystals include polyester type, polyether type, polyazomethine type8. Polythioester type, polythioether type.

Polysiloxane-based, polyamide-based, polyimide-based, etc. can be used. As the side chain type ferroelectric polymer liquid crystal, polymethacrylic, polyacrylic, polychloroacrylic, polyether, etc. can be used.

The main chain type, side chain type, and main chain-side chain type ferroelectric liquid crystal compounds may be used alone, or two or more of the same or different types of liquid crystal polymer compounds may be used as a mixture. Alternatively, a copolymerized product may be used.

Next, specific examples of ferroelectric polymer liquid crystals that can be used in the present invention are shown below, but the present invention is not limited thereto.

-f< Ht -CHh- m≧5゜n=4~18 1+cH2-CHh- Mushroom! = 1~2゜k=1~2゜n=4~18゜m≧5 →beHa−CHh− j;O or 1 m≧5 1+−CH2−chHh− y =(1,1−1. Q, m = 4-12.
n≧3 again. Optically active polymer liquid crystals that can exhibit ferroelectricity by blending may also be used. A specific example is shown below.

+ pull 1□-CIQ7- J=0 or 1 m≧5 (-=2~15゜x+y=1) (x+y=1.@□=2~l5) (x+y=1) (x+y=1) (x+y =l, m2=2~15) (x+y=1,1shi2~is) (m, =1~5) (Otori, =1~3゜1=t~20) (Kasumi, =0~5) (m, -0 to 5) (teeth, = 0 to 5) (lI% = θ to 5) In the polymer liquid crystal composition of the present invention, a polymer containing a ferroelectric polymer liquid crystal and a low molecular liquid crystal It is possible to use a liquid crystal composition, but as a low molecular liquid crystal, a ferroelectric low molecular liquid crystal is preferably used because it is compatible with a ferroelectric polymer liquid crystal. In addition, the content of low-molecular liquid crystal in the mixture of ferroelectric polymer liquid crystal and low-molecular liquid crystal does not have to be ferroelectric low-molecular liquid crystal as long as it does not impair the characteristics of ferroelectric polymer liquid crystal. is 1 to 99% by weight, preferably 5 to 50% by weight
or desirable.

Further, it is preferable that the polymer liquid crystal composition of the present invention has a glass transition point.

Next, in the polymer liquid crystal composition of the present invention, the dichroic dye used for the host is not particularly limited as long as it is a guest-host type liquid crystal color dichroic dye that is normally used in low molecular liquid crystals. You can use it. However, it is necessary to consider the compatibility between the dichroic dye and the ferroelectric polymer liquid crystal.

The ferroelectric polymer liquid crystal and the dichroic dye are sufficiently compatible by simply mixing them, keeping both at a temperature equal to or higher than the isochoric phase transition temperature of the ferroelectric polymer liquid crystal, and then cooling the mixture. If necessary, a method may be used in which both are dissolved in a soluble solvent and homogenized by stirring with a stirrer or applying ultrasonic waves, and then the solvent is distilled off.

Further, the content of the dichroic dye in the polymer liquid crystal composition of the present invention varies depending on the type of dichroic dye, but is usually 50 parts by weight or less, preferably 50 parts by weight or less based on 100 parts by weight of the ferroelectric polymer liquid crystal. is preferably in the range of 0.5 to 30 parts by weight.

Specific examples of dichroic dyes are listed below, but the invention is not particularly limited to these.

<660nm ~> 687na+ 0.74(BP) (Blue) 760n
m 0.7(PCB) 705nm O,71(PCH) 810nm O,63(BP) 665nm O,64(PCH) 6660nm 0.74(PCI) <55On-~530nm> 494npeng0.68(BP) (Orange) O8nm 0.76 (BP) 535n 0.79 (PCI) 4370 layer (yellow) 457n (yellow-orange) <64ns> 648n 0.75 (BP) (Blue) 640n 0.73 ( P(:H) NO, +N-N-@-N(C)13)! 499n (orange) ku400-450nzen> H9C4+N=N-o-N-N-kuζ)) oc, o.

98ns 0.75 (BP) 438n 0.76 (PCI) 455n amount 0.73 (PCB) 38nm 0.77 (PCI) 640n @ 0.77 (BP) 30nm 0.77 (PCI) rl=l 532na ( Red) n = 2 610n layer (Blue) n = 3 64
0na (blue-green) <600-610 layers> 12nm 0.72 (BP) (blue) 610n 0.79 (BP) 56nm (red-purple) 5930 (blue) 5550 layers (red-purple) 563n-maro (purple) ) 6050 0.71 (BP) <550-600n> 573rv O, 77 (BP) 595 (550) 0 0,74 (pcn) 46nm 0.71 (PCI) In addition, the mesogen group of polymer liquid crystal A ferroelectric polymer liquid crystal obtained by copolymerizing dye molecules can also be used.

Figure 1 shows a ferroelectric polymer liquid crystal display element (hereinafter referred to as
It is an explanatory diagram showing an example of a liquid crystal display element (referred to as a liquid crystal display element). In FIG. 1, the liquid crystal display element of the present invention has a ferroelectric polymer liquid crystal and a dichroic dye between a pair of substrates 2 on which a striped transparent electrode 3 and an insulating film 4 are formed. a polarizing plate which holds a display layer 5 in which a polymer liquid crystal composition containing a polymer liquid crystal composition is stretched and oriented, and has a vibration axis perpendicular to the stretching direction of the polymer liquid crystal composition of the display layer 5 on the outside of one substrate 2; l
A backlight IO is provided on the outside of the other substrate 2 with a resistance heating element 9 interposed therebetween.
The display state is identified by passing the irradiated light from the polarizing plate l through the polarizing plate l.

The method for forming the display layer is as follows: 1. For example, after mixing a ferroelectric polymer liquid crystal and a dichroic dye, a film formed using a normal polymer film forming method is stretched in a temperature range that exhibits a chiral smectic phase. Alternatively, the blend may be dissolved in a soluble solvent, coated on a suitable plastic substrate, dried, and co-stretched on the plastic substrate.

The display layer thus formed may be attached to a substrate with electrodes to produce a display element having a structure as shown in FIG.

Further, FIG. 2 is an explanatory diagram showing another example of the liquid crystal display element of the present invention, which has a multilayer structure and is capable of displaying multiple colors. In the figure, three polymer liquid crystal compositions each containing a ferroelectric polymer liquid crystal and a different dichroic dye were stretched and oriented between three pairs of substrates 2 and 2 with transparent electrodes 3 attached. Three element layers 11 holding respective display layers 6, 7.8 are laminated with the stretching direction of the polymer liquid crystal composition aligned in the same direction, and the display layer is placed on one outer substrate 2. 5
A polarizing plate 1 having a vibration axis perpendicular to the stretching direction of the polymer liquid crystal composition is provided, and a backlight IO is provided on the other outer substrate 2, and the irradiated light from the backlight is directed to the polarizing plate. The display state is identified through 1.

[Example] The present invention will be explained in more detail with reference to Examples below.

Example 1 For polymer liquid crystals represented by the following structural formula (21).

A dichroic dye represented by the following structural formula (22) was added at a weight percentage of 2.5 wt% to the polymer liquid crystal, and 90
The mixture was left at 10°C for 10 minutes and then cooled to room temperature.

The polymer liquid crystal composition thus obtained was sandwiched between two transparent electrode-attached glass substrates using a 10 mm thick polyimide film as a spacer. In the liquid crystal cell formed in this way, a voltage of 50 Vpp was applied between the upper and lower electrodes at a temperature of 20°C.
When a square wave voltage with a frequency of IHz was applied and the current flowing through the cell was monitored, eight current waveforms corresponding to polarization reversal were measured.

Also, instead of a triangular wave, a DC voltage of ±50v is applied to both types of FIF.
Polarize the texture while alternating with lJI using the switch! When IQ was observed using a 11-microscope, it was confirmed that there was a phase in the amount of S in the system in which the dichroic dye was dissolved from 0 or more, which was observed to be a change in texture corresponding to switching.

The phase transition temperatures in this system are: 3°C 25°C 85°C

Met.

Structural formula (21) The phase transition temperature is: 0°C 20°C 80°C
So.

Therefore, it was confirmed that it also has an S-C8 phase, and that it is switching at the same time as a dichroic dye or a liquid crystal mesogen.

Structural formula (23) %Formula% Structural formula (22) Example 2 An experiment was conducted in the same manner as in Example 1 except that 5 wt% of the dye represented by the following structural formula (23) was used.Example 3 A dichroic dye LSR-405 manufactured by Mitsubishi Kasei ■ was mixed with the polymer liquid crystal represented by the structural formula (24) in an amount of 10% based on the weight of the polymer liquid crystal, and a film with a thickness of 5 mm was formed from the molten state. Formed. Its phase transition temperature is 25℃ 7
0°C 80°C glass-1→Sac'->SmA->Iso.

Met.

The obtained film is passed between two pairs of rollers with different surface speeds in an environment exhibiting a liquid phase or an SsC'' phase to perform free width stretching, and then slowly cooled to below 30°C (Tg). A uniaxially oriented film with a thickness of 2 final layers was obtained.A substrate with a striped ITO film in the same direction as the polarization direction on a 0.7 ts thick polarizing glass on both sides of this film, and a normal glass substrate. I connect the board with ITOM on the stripe to
They were bonded so that the TOs were perpendicular to each other, and a liquid crystal display element as shown in FIG. 1 was obtained. At this time, polarizing glass was bonded so that the vibration direction was the same as the stretching orientation direction.

The obtained liquid crystal display element was placed on a resistance heating element having a backlight source so that the polarizing glass surface was on the opposite side from the backlight source, and the display layer was heated to 40°C (temperature showing Sac" phase). When a voltage of 10 V was applied between the ITO films in a matrix structure, a red display was obtained in the part of the white background where the voltage was applied.Also, in this state, the temperature of the display layer was Even when the voltage was turned off after the temperature was lowered to 30°C (Tg) or less, the display state remained unchanged.

Structural formula (24) % formula %) The same polymer liquid crystal as used in Example 3, manufactured by Mitsubishi Kasei Motors,
Dichroic dye LSR-405 (red), LSY-116 (yellow).

Three types of polymer liquid crystal compositions each containing 10% by weight of LSB-350 (blue) with respect to the polymer liquid crystal were prepared, and a -axially stretched oriented film with a thickness of 2 mm was prepared in the same manner as in Example 3. I got it. Three sets of element layers were created by adhering striped transparent electrodes made of a 1254 m thick polyester film with striped transparent electrodes sandwiching each axis-stretched oriented film so that they were facing and orthogonal to each other. As shown in Figure 2, the layers are stacked so that the stretching orientation directions are all the same, and the layers are placed in close contact with the backlight light source, and a polarizing plate is closely attached to the top of Figure 2 so that the vibration direction is perpendicular to the stretching orientation direction to display the liquid crystal display. I got the element. The background color of the liquid crystal display element thus obtained is white.

When the lower electrode of the layer corresponding to the yellow color of this liquid crystal display element is energized and heated to a temperature that indicates polymer liquid crystal or SsC, when a voltage of IOV is applied between the upper and lower electrodes, only the part where the voltage is applied becomes white. A yellow display was made on the background. Red and blue displays were also possible in the same way. Also, when heating and voltage were applied between the three layers, a black display was made, indicating that multicolor display is possible. This display shows that in the presence of an electric field,
Even after the heating was stopped and the electric field was turned off, the display remained unerased.

Example 5 Nisso was added to the same polymer liquid crystal composition used in Example 3.
2 ferroelectric liquid crystal C5-1014 manufactured by C. Co., Ltd. was mixed at a weight percentage of 30% with respect to the polymer liquid crystal, a stretched oriented film with a thickness of 2p was prepared in the same manner as in Example 3, and a striped transparent electrode was attached. The stretched and oriented film was sandwiched and bonded so that the electrodes of the polyester film thus prepared faced each other and the striped transparent electrodes were perpendicular to each other. Furthermore, a backlight and a polarizing plate were arranged in the same manner as in FIG. The voltage between the upper and lower electrodes of the liquid crystal display element thus produced was 10V.
When the voltage was applied, a red display appeared in that area, confirming that room temperature operation was possible.

[Effects of the Invention] As explained above, according to the present invention, a guest-host type polymer that can easily form a film containing a ferroelectric polymer liquid crystal and a dichroic dye and can be uniaxially aligned. A liquid crystal composition can be obtained.

Further, by using the polymer liquid crystal composition, it is possible to easily obtain a guest-host type liquid crystal display element that has good viewing angle characteristics and is capable of multicolor display without the need for alignment treatment on the substrate.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing one example of the liquid crystal display element of the present invention, and FIG. 2 is an explanatory diagram showing another example of the liquid crystal display element of the present invention. 1... Polarizing plate 2... Substrate 3... Transparent electrode 4... Insulating films 5 to 8... Display layer 9... Resistance heating element 10... Balacryte 11... Element layer

Claims (9)

[Claims] (1) A ferroelectric polymer liquid crystal composition comprising a polymer liquid crystal having a liquid crystal phase exhibiting ferroelectric properties and a dichroic dye. (2) Claim 1 in which the liquid crystal composition has a glass transition point.
The ferroelectric polymer liquid crystal composition described above. (3) The ferroelectric polymer liquid crystal composition according to claim 1, wherein the liquid crystal composition contains a ferroelectric low molecular liquid crystal. (4) A ferroelectric polymer liquid crystal composition containing a polymer liquid crystal having a liquid crystal phase exhibiting ferroelectricity and a dichroic dye is stretched and oriented and held between a pair of electrodes, and 1. A ferroelectric polymer liquid crystal display element comprising a polarizing plate having a vibration axis perpendicular to the stretching direction of a ferroelectric polymer liquid crystal composition, the display state being identified through the polarizing plate. (5) The ferroelectric polymer liquid crystal display element according to claim 4, wherein the ferroelectric polymer liquid crystal composition has a glass transition point. (6) The ferroelectric polymer liquid crystal display element according to claim 4, wherein the ferroelectric polymer liquid crystal composition contains a ferroelectric low molecular liquid crystal. (7) 2 of the element layer formed by stretching and holding a ferroelectric polymer liquid crystal composition containing a dichroic dye and a polymer liquid crystal having a ferroelectric liquid crystal phase between a pair of electrodes; comprising a polarizing plate formed by laminating more than one layer with the stretching direction of the ferroelectric polymer liquid crystal composition aligned in the same direction, and having a vibration axis perpendicular to the stretching direction of the ferroelectric polymer liquid crystal composition, A ferroelectric polymer liquid crystal display device characterized in that multicolor display states can be identified by differences in absorption bands of dichroic dyes contained in each device layer through the polarizing plate. (8) The ferroelectric polymer liquid crystal display element according to claim 7, wherein the ferroelectric polymer liquid crystal composition has a glass transition point. (9) The ferroelectric polymer liquid crystal display element according to claim 7, wherein the ferroelectric polymer liquid crystal composition contains a ferroelectric low molecular liquid crystal.