JPS61247783A - Liquid crystal composition - Google Patents

Abstract

PURPOSE:To obtain a liq. crystal compsn. having excellent thermooptical properties and suitable for thermal writing, by adding a chiral smectic liq. crystal to a smectic liq. crystal. CONSTITUTION:A chiral smectic liq. crystal of the formula (wherein R1 is a 7-13C alkyl; and R2* is a 5-10C alkyl having an asymmetric carbon atom in its molecule) is added to a smectic liq. crystal such as 4-octyl-4'-cyanodiphenyl or N-(4-octylbenzylidene)-4-cyanoaniline to obtain the title compsn.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a liquid crystal composition for thermal writing utilizing the thermo-optical properties of a liquid crystal compound.

(Prior Art) In order to store and display high-resolution, large-capacity information, research has been conducted into applying the thermo-optic effect of liquid crystal compounds. Is it possible to control the liquid crystal by sandwiching the liquid crystal compound between the transparent substrates? hr Resee half capacity or E18, changes liquid crystal compound to isotropic state.

If this is cooled rapidly, the liquid crystal compounds will not be able to arrange themselves in a regular manner, and light scattering will occur in that area.
Appears cloudy. The aim is to use this property for information storage and apply it to information display by projection or direct viewing.

Among liquid crystal compounds, there are compounds that exhibit such properties particularly prominently using compositions containing smectic liquid crystal as a matrix and cholesteric liquid crystal as an additive.

However, in order to display information clearly, the contrast between the cloudy part and the transparent part must be clear. As a method to clarify the contrast, (
4. Improvements in liquid crystal compounds themselves, (b) search for effective additives, and use of auxiliary materials (such as the use of aluminum reflective films) are underway, and new liquid crystal compounds are being created. Currently, the search for effective additives is being carried out through trial and error, including the idea of mixing them with other liquid crystal compounds.For example, n-octylcyanobiphenyl, terphenyl, anthracene, and There have been attempts to add anthracene, triphenylene, etc. as dopants (10th Liquid Crystal Symposium (1984)] 8AO6), and addition of cholesteric liquid crystals (cholestegyl nonanoate) to n-octylcyanobiphenyl and cyanooctyloxy-4-4-biphenyl. Research is being conducted to measure changes in contrast by mixing cholesteric liquid crystals with smectic liquid crystals (10th Liquid Crystal Symposium (1984) 13AO5). In addition, optically active liquid crystal compounds (such as CB) are added to smectic liquid crystals.
-15) has also been studied to enhance contrast before and after thermal writing.

c) Problems to be Solved by the Present Invention) As a result of extensive research, the present inventors found that when thermal writing was performed on a liquid crystal composition in which chiral smectic liquid crystal was added to smectic liquid crystal, the contrast did not deteriorate. In fact, we have found that it actually improves.

The present invention has been made based on such knowledge.

(Means for Solving the Problems) The liquid crystal composition provided by the present invention is produced as follows.

Smectic liquid crystal compounds, e.g. 4-octyl tLy
-4'-cyanobisene/', 4-7 crabroux 4'
-cyanobiphenyl, N-(4-octylbenzylidene)-4-cyanoaniline, terephthalbis(4-n-
Butylaniline, 4,4'-azoxybenzoic acid diethyl ester, 4(4-benthylphenyl/l/
1 benzoic acid 4'-pentylphenyl ester alone or in combination (for example, S, sold by Merck & Co., Ltd.
, S, etc.), and a commonly used infrared absorbing dye such as bis-(4-dimethylamino-1
,2-benzenethiolenenitske〃tetrabutylammonium, bis(4-dimethylamino-5-meth4-/L/-
A chiral numectic liquid crystal compound was added as a dopant. The chiral smectic liquid crystal used here is p-1.
! Converted benzal-p-aminocinnamic acid optically active a! Examples include lekyl ester. The chemical formula is as follows.

E, -o%cn=N(paddlecH=cH-coob,"(
f6 only represents a C- to C1-alkyl group, and a C- to C1-alkyl group has an asymmetric carbon atom in the molecule.

) More specific examples include the following.

R, R2 The liquid crystal composition for thermal writing thus obtained is filled using a commonly used device and method to prepare a liquid crystal cell, and the cell is set in a laser beam writing device to perform thermal writing.

The amount of light transmitted before and after writing was measured for the white area caused by thermal writing using Photomaru, and the contrast (CF?1) was calculated according to the following formula.

Amount of light transmitted after writing Examples will be described in detail below.

Example 1 1.5% by weight of an infrared absorbing dye was added to commercially available smectic liquid crystal S (manufactured by Merck & Co., Ltd.), and a chiral smectic liquid crystal compound was added.
．． A liquid crystal composition was prepared by adding 0% by weight. Separately, a sample without the chiral smectic liquid crystal compound was similarly prepared. Each liquid crystal composition was filled into a cell according to a conventional method to produce a liquid crystal cell for thermal writing. Writing was performed on this using a laser beam with a wavelength of 813 μm, and the contrast before and after writing was compared.

μm Compound addition amount wt% (1) 12 0 7.36 (2
1119,08,51

Claims (1)

[Claims] A liquid crystal composition with excellent thermo-optical properties characterized by adding chiral smectic liquid crystal to smectic liquid crystal.