JPS5829875A - Liquid crystal composition and liquid crystal color display element - Google Patents

Abstract

PURPOSE:To obtain a liquid crystal which is high in color saturation and excellent in the color effect, can efficiently be obtained, and is useful for liquid crystal color display element of high visibility, by incorporating, into a liquid crystal, a pleochroic yellow dye and a pleochroic blue dye in a specified proportion whose absorption maximum wave lengths are in specified ranges. CONSTITUTION:A pleochroic yellow dye whose absorption maximum wave length is in a range of 400-470nm and a pleochroic blue dye whose absorption maximum wave length is in the range of 630-700nm in a proportion of 0.1- 0.6 are added to a liquid crystal. The obtained liquid crystal composition 9 is filled in between electrode base plates 7 which are coated with transparent electrodes 8 and at least one of which is transparent to obtain the liquid crystal color display element. When this element is not energized with an electric field, it indicates a clear green color shapde, while when it is energized with an electrid field, becomes almost colorless. As a pleochroic yellow dye yellow pleochroic dye G206, may be mentioned and, as a pleochroic blue dye, compounds of formulaeI, II and III may be mentioned.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel liquid crystal composition containing a pleochroic dye and a novel guest-host type liquid crystal color display element capable of displaying colors using the composition.

A pleochroic dye is added to an electric field aligned nematic liquid crystal or a nematic-cholesteric mixed liquid crystal, and the liquid crystal molecules are aligned by an electric field using the dielectric anisotropy of the liquid crystal molecules and the optical class anisotropy of the pleochroic dye molecules. A display method in which color is changed by changing the orientation direction of dye molecules is known as &ll guest-host effect. The display cluster using the guest-host effect has the characteristics that any display color can be selected by selecting the hue of the pleochroic dye, and the viewing angle is wide, making it superior to other liquid crystal display methods. ◇As the pleochroic dye, a pleochroic dye that cures an appropriate hue is often used alone. No excellent pleochroic dye has been found that can provide some hues such as yellow or yellow pleochroic dyes alone, and liquid crystal compositions with desired hues such as green have been obtained by mixing yellow and yellow pleochroic dyes.

However, in the past, when obtaining these mixed colors, the standards for what materials should be used were unclear, and it was necessary to repeatedly examine suitable combinations of materials through trial and error, and then obtain the desired hue from among them. was. Therefore, it is clear that the conventional method described above requires a huge amount of labor to obtain the desired hue, resulting in extremely low productivity. A hue that cannot be seen,
That is, a new liquid crystal composition exhibiting a particularly vivid green hue among mixed hues, which has the highest saturation and excellent color effects, and which can be obtained extremely efficiently, and the liquid crystal composition An object of the present invention is to provide a highly visible liquid crystal color display element capable of displaying colors using objects.

The liquid crystal composition according to the present invention has a mixture ratio of a yellow pleochroic dye having a visible absorption maximum wavelength of 400 to 470 nm and a blue pleochroic dye having an absorption maximum IIIL length of 630 to 700 mm as a pleochroic dye. A pleochroic dye adjusted to have a density of 0.1-0.6 is added to the liquid crystal.

Here, the mixing ratio is defined as the absorbance AY of the yellow pleochroic dye at the maximum absorption wavelength 2M and the absorbance A3 of the blue pleochroic dye at the maximum absorption wavelength λB. The ratio of AY/(A
Y1AB) means C. Furthermore, any type of crystal material to which the pleochroic dye is added may be used.Furthermore, the liquid crystal color display element of the present invention has a structure in which the liquid crystal material is filled between electrode substrates on which transparent electrodes are formed.

In order to understand the superiority of the liquid crystal composition according to the present invention, a colorimetric evaluation method will be briefly explained. m = color in quantitative form
Calorimetric methods are often used. The lateral color method is based on the fact that the color states that we sensually perceive can be physically measured, such as spectra, and that they correspond well to the color states we sensually perceive in the form of The color condition is quantitatively evaluated using the amount of
Please refer to literature such as ``Perceived Colors and Their Display'' by Ikeda, TV Television University Technical Report, VVI32-1.

Among such colorimetric evaluation methods, the present inventor uses the uniform color space i, * a * b * color system to evaluate the liquid crystal color display element filled with the liquid crystal composition containing the pleochroic dye. Color was quantitatively investigated.

Hereinafter, examples of the liquid crystal composition and liquid crystal color display element according to the present invention will be described in detail using figures.OL*, *b*
In the color system, as the quantities corresponding to the three attributes of color (hue, saturation, lightness)) Brightness Ri1 Saturation C- West β1 "Nai-
1 hue angle H-1 (a) is defined, and the colors of the liquid crystal composition and liquid crystal color display element were evaluated using these amounts.

Colors that are sensually pleasing include: 1. If they have the same hue; It can be said to be the highest fi color. A green hue should be obtained by mixing a yellow pigment and a blue pigment, but among the 41 properties of each pigment used, it is important to know how to adjust the maximum absorption wavelength and their mixing ratio, which are the most important characteristics. It was not always clear whether rubbing was a good idea.0 Figure 1 shows an example of changes in hue angle depending on the mixing ratio of each pigment.0 Hue angle is information about hue, one of the three attributes of color, expressed in angles. , H-θ° is red, H-90° is yellow H-18
0' is green, H-2700 is blue, and two continuous hues are distributed. 0 Figure 1 shows the yellow pigment with λwax = "'"" and each yellow of λ!n, xs-600.636.684 spit. This diagram shows the hue angle obtained for each mixing ratio when dyes are mixed.As λgnax of zero background color, 1
4 yo λH111z ” 600 n tnl 2nd ma λ
,,8-636m1!1% 3 is λ,,,xx684
In order to realize a continuous hue between yellow and green, which corresponds to the case of am, the mixing ratio is λ□, and in the case of X-@Ozhai, the mixing ratio is 053 to
For G, 58, λmax = 636 nm, ozs~
Q, 60. 0.1 for λmllK-684mm
It can be seen that this is a case of 4 to 0.50. Thus either λ. Even with 8x, it is possible to achieve a hue corresponding to H-sd' to 1800, but in the case of λmax m600nm, the tolerance range for the ll4r ratio is too narrow to achieve the above hue range, resulting in significant manufacturing problems due to reproducibility problems. λrnax #636.68 according to the present invention for disadvantageous OC errors
In the case of 4 nm, the mixing ratio (on the other hand, it changes slowly, the tolerance range for the mixing ratio is widened, it is advantageous in terms of hue reproducibility, and the manufacturing yield is improved. On the other hand, the hue change is almost linear, from yellow to
Any hue between green can be easily achieved.

FIG. 2 shows the change in color saturation obtained with the same dye combination as in FIG. 1. In 1, it was shown that the same hue can be obtained by changing the mixing ratio in any case where the λmax of the blue dye is 600.636.684 nm. Therefore, colors with higher saturation can be considered superior colors.

As can be seen from FIG. 2, the saturation of the mixed color is generally lower than that of each individual pigment. In particular, in the case of λmaw-600 nm, the mixing ratio range is 0.53 to 0.58 in which the hue of low 900 to 18o0 can be obtained.The saturation of odor C is almost 0. That is, when a blue dye with λmaw -600rIm is used, only a greenish hue that is almost achromatic can be obtained. On the other hand, λwax −63 according to the present invention
In the case of 5,68411 m, 5,6 is the above λmax-600
The color saturation is significantly higher than in the case of am.

The green liquid crystal composition and the liquid crystal color 67 according to the present invention with a yellow combination of λmax -468 ntnoJ%, details the superiority of the hue of the device, that is, the ability to reproduce highly saturated hues. However, 'Aze・, λm of the permanent pigment
Similar results were obtained when aX was in the range λmax=400 to 470 nm. λmax of yellow pigment is λmm
If the wavelength is within the range of 400 to 479 nm, λmax is a short wavelength machine, and the hue change with respect to the mixing ratio is gradual. (.

Example 1 Nematic liquid crystal E8 (BDHCh
yellow pleochroic dye 0206 (Japan Photosensitive Color Research Institute) to 0.5 to 1. ovt and a blue pleochroic dye with a compound having the molecular structure shown below.
．． The maximum absorption wavelength in the oJ viewing range of the liquid crystal composition containing 5 to 1.7 wt % is λmax = 464.636 nm, and the mixing ratio based on the absorbance at each maximum absorption wavelength is Q, and each concentration ratio is from 25 to 061. It changed to a bright greenish hue.

A liquid crystal color display element as schematically shown in FIG. 3, in which the liquid crystal composition . The color display element exhibited a clear green hue when no electric field was applied, and became almost colorless when an electric field was applied.

Example 2 In place of the compound used as the blue pleochroic dye in Example 1, Compound B having the molecular structure shown below was used in the order of 1.0 to 2. The maximum absorption wavelength in the visible range of the liquid crystal composition to which Owt % is added is λmax-468.670n.
m, and the mixing ratio based on absorbance at each absorption maximum wavelength varied from 0.2 to 0.05 for each concentration ratio, and a bright greenish hue was exhibited.

Example 3゜Example 1. In place of the compound used as a yellow pleochroic dye in the above, a compound C-t- having the molecular structure shown below was used. The liquid crystal composition to which Owt% ONIIJ is added has a maximum absorption wavelength in the visible range of λmax-468.684 nm, and the mixing ratio based on the absorbance at each maximum absorption wavelength is 0.
It varied from 15 to 05 and exhibited a bright greenish hue.

Example 4゜Liquid crystal material E8i used in Example 1 0206.1.22w
1% and 0.73 wt'lL of the compound used as the backing dye in Example 1, Example 2. The maximum absorption wavelength in the visible range of the liquid crystal composition to which 0.96 wt* of Compound (1), which was used as a blue dye, was added was λrnax-464.6.
46 nm, the mixing ratio based on absorbance at each absorption maximum wavelength was 0.44, and a bright green color was exhibited.

FIG. 4 shows the absorption spectrum IO of the composition.

The above composition *Example 1. The liquid crystal color display element filled in the liquid crystal cell used in the above exhibited a good hue change, which was green without an electric field and almost colorless when an electric field was applied.

As described above in detail in the examples of the present invention, a liquid crystal composition with a green hue, which could not be obtained with a conventional mono-etching dye, can be obtained by using a yellow dye according to the present invention having a 2 m a x of 400 to 470 nm,
By mixing blue dyes having a λmax of 630 to 700 am at an appropriate mixing ratio, a liquid crystal composition having a greenish hue with high saturation and a liquid crystal color display element using the same were provided.

[Brief explanation of the drawing]

Uniform color space L* used in the embodiment of the present invention,
A schematic cross-sectional view of a liquid crystal color display element showing the mixing ratio of yellow and blue dyes in the *b* system.
FIG. 3 is a diagram showing an absorption spectrum of a liquid crystal composition used in FIG. 1...Change in hue angle H with respect to the mixing ratio of yellow dye λmax-468am and blue dye λmax=600 nm. 2...Hue angle H for the mixing ratio of yellow pigment λmaxm468ntn and blue pigment λmax=636nnn
Change in 0 3...The hue angle l(
change of. 4...Change in saturation C with respect to the mixing ratio of yellow color chip λmmK-468ntn and blue pigment λmaz-fioonm. 5... Change in saturation C with respect to the mixing ratio of yellow dye λmax ~ 46gam and blue dye λmax = 636 nm. . 6...Color # for the mixing ratio of yellow dye λm5x-468nrn and blue color chip λmax=684 nm,
Changes in C. 7...tWi substrate 8...Transparent electrode
9...Liquid crystal composition 10...Example 4.
Polarized light absorption spectrum in the optical axis direction in the visible region of the liquid crystal composition. -1゛＼ Figure 1 Mixed upper FSA+=AY/(AY+AB) Figure 2 00 0.5/, 0-/Consolidation ratio A
, = AY/ (AY + Al3) Figure 3 v7'l Procedural Amendment (!L Ship 57.9.20 Showa Year Month 1) Indication of Director General - Name of 1983 Patent Application No. 117353 SHJ- Relationship to the case of the person who displays Sumitomo:, 0+ Building, 1ip-1137-8, Shiba, Minato-ku (Contact information: Patent Department, 11hon Denki Co., Ltd.)
5 Column 6 for detailed explanation of the invention in the specification to be amended Contents of the amendment (1) The amendment is made to the 18th line of the 8th line of the specification.

Claims (1)

[Scope of Claims] (fl e A pleochroic yellow dye with a maximum wavelength of 400 nm to 470 nm and a maximum absorption wavelength of 63 Q nm to 70 nm.
Both include the pleochroic blue dye in 0zun, and each of the yellow and blue pleochroic JIII! The mixing ratio of 01 to 0.
6. A liquid crystal composition characterized in that: (2) In a liquid crystal color display element formed by filling a liquid crystal composition obtained by adding a pleochroic dye between a pair of electrode substrates coated with a transparent electrode, at least one of which is transparent, as the liquid crystal composition, The pleochroic dye has a maximum absorption wavelength of 400 to 470 nm in the visible range, and a pleochroic blue dye has a maximum absorption wavelength of 630 nm to 700 ntn. 1. A liquid crystal color display element characterized by using a color dye having a mixing ratio of 0.1, 0, and 6.