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Cholesteric liquid crystal composition and liquid crystal display element

A technology of cholesteric liquid crystals and compositions, applied in liquid crystal materials, optics, instruments, etc., can solve problems such as color change, wide operating temperature range, and reflection wavelength shift

Pending Publication Date: 2021-01-12
DIC CORP
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0008] Due to the temperature dependence of the chiral pitch that cholesteric liquid crystals have, cholesteric liquid crystal compositions have the following disadvantages: the selective reflection wavelength λ is shifted due to changes in the ambient temperature when being driven as a device, and the color luster change
However, it is not yet known to satisfy the various characteristics required for cholesteric liquid crystal compositions, namely, large dielectric anisotropy, wide operating temperature range, stability at low temperatures, desired selective reflection wavelength, reliability against external light, etc. A specific host liquid crystal composition that meets multiple requirements such as high performance and can solve the disadvantages

Method used

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  • Cholesteric liquid crystal composition and liquid crystal display element
  • Cholesteric liquid crystal composition and liquid crystal display element
  • Cholesteric liquid crystal composition and liquid crystal display element

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0117] Table 3 shows the compositions of Example 1 and Comparative Example 1.

[0118] Compositions other than the third component in the table below were prepared to produce nematic liquid crystal compositions (host liquid crystal compositions), and their physical properties were measured. In addition, a compound as the third component of the chiral compound was added to these host liquid crystal compositions to prepare a cholesteric liquid crystal composition so that the selective reflection wavelength at 25° C. was about 560 nm.

[0119] [table 3]

[0120]

[0121] The physical property values ​​of each composition and the temperature dependence of the selective reflection wavelength are shown below.

[0122] [Table 4]

[0123]

[0124] Compared with Comparative Example 1, the T of the host liquid crystal composition of Example 1 except the third component NI The points are equal, the melting point is low (=wide liquid crystal temperature range), the viscosity (η) ...

Embodiment 2～ Embodiment 5

[0128] The compositions of Examples 2 to 5 are shown in Table 5.

[0129] Host compositions other than the third component in the following table were prepared in the same manner as in Example 1 to produce a nematic liquid crystal composition (host liquid crystal composition), and their physical properties were measured. In addition, a compound as the third component of the chiral compound was added to these host liquid crystal compositions to prepare a cholesteric liquid crystal composition so that the selective reflection wavelength at 25° C. was about 560 nm.

[0130] [table 5]

[0131]

[0132] [Table 6]

[0133]

[0134] It can be seen that, compared with the host liquid crystal composition of Comparative Example 1, the host liquid crystal compositions of Examples 2 to 5 other than the third component have lower melting points (=wider temperature range of liquid crystals), smaller viscosity (η), and intermediate The electrical anisotropy (Δε) is slightly larger an...

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Abstract

The invention provides a cholesteric liquid crystal composition having positive dielectric anisotropy and a liquid crystal display element using the same. The cholesteric liquid crystal composition contains a compound represented by general formula (1-1), a compound represented by general formula (1-2), a compound represented by general formula (2-1) as a second component, a second component having a neutral dielectric property, and at least two optically active substances having different temperature dependencies of chiral pitch lengths from each other.

Description

technical field [0001] The present invention relates to a cholesteric liquid crystal composition useful as a material for a display element and a display element using the same. Background technique [0002] A liquid crystal display element using a cholesteric (chiral nematic) liquid crystal composition that imparts a twisted orientation to the liquid crystal phase by adding an optically active compound to the liquid crystal composition has bistability, and therefore can be used in applications that require particularly low power consumption. e-books, e-labels, display panels, etc. The bistability of the cholesteric liquid crystal can be realized by switching the planar state and the focal conic state by applying a pulse voltage, and the states of the planar and focal conic can be maintained even when the voltage is turned off (OFF) , so the bistability is also called memory. [0003] A liquid crystal display device using a cholesteric liquid crystal exhibits a specific se...

Claims

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Application Information

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IPC IPC(8): C09K19/46G02F1/137G02F1/1333
CPCC09K19/46G02F1/1333G02F1/13718
Inventor 丸山和则野中祐贵
Owner DIC CORP
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