Liquid crystal composition and liquid crystal display element

Details Liquid crystal composition and liquid crystal display element Liquid crystal composition and liquid crystal display element

1998-05-04

2001-03-27

Kelly, C.H. (Department: 1721)

Compositions

Liquid crystal compositions

Containing nonsteryl liquid crystalline compound of...

C252S299660

Reexamination Certificate

active

06207075

ABSTRACT:

DETAILED DESCRIPTION OF THE INVENTION
Field of the Invention
The present invention relates to a nematic liquid crystal composition containing at least one chiral additive arranged within a sealed cell formed of two substrates having transparent electrodes and a liquid crystal display element with use of the said liquid crystal composition.
In more detail, the invention relates to a liquid crystal composition suitable for a super twist birefringence (STN) mode and a liquid crystal display element with use of the said liquid crystal composition.
Description of Prior Art
There have been proposed and put to practical uses one after another a twist nematic (TN) mode, a super twist birefringence (STN) mode and an active matrix (AM-LCD) mode etc. Amongst there of, a super twist birefringence (STN) mode proposed by T. J. Scheffer et al. (Appl. Phy. Lett., 45 (10), 1021 (1984)) wherein alignments of liquid crystal molecules in the upper and lower substates are twisted at from 180 to 270° is adapted as LCD's for personal computers and word processors etc. and it becomes to be required more various improvements as to its characteristics.
The liquid crystal composition used for the liquid crystal display element of the said STN mode is required to have the following characteristics:
(1) a voltage-transmittance characteristic (a sharpness) being sharp in order to increase a contrast of the liquid crystal display element,
(2) a phase transition temperature (a transparent point) being high in order to decrease a change in coloring due to a temperature dependency of a refractive anisotropy (&Dgr;n), and
(3) a viscosity (&eegr;) being low in order to decrease a response time as possible.
Amongst these characteristics, in particular, correspondency to coloring and correspondency to animation are strongly required recently, and particularly improvements of the above-mentioned characteristics (1) and (3) become important.
However, even though such liquid crystal compositions have been zealously investigated, improvements have been always required under present conditions.
Problem to be Solved by the Invention
We inventors investigated various compositions with use of various liquid crystal compounds in order to solve these subjects, and found that the objects can be attained in the case of using a liquid crystal composition according to the present invention as a STN display element.
As clear from the above description, an object of the invention is to propose a liquid crystal composition which satisfies various characteristics required for the above- mentioned STN display mode and simultaneously has a superior voltage-transmittance characteristic (a sharpness) for corresponding to coloring and also a low viscosity for corresponding to a high-speed responce.
Means to Solve the Problem
The present invention is explained as follows.
(1) A liquid crystal composition characterized in that at least one compound expressed by the general formulae I-a and I-b
(wherein, R
1
denotes an alkyl group having from 1 to 10 carbon atom(s), optional one or non-adjacent two or more than two methylene group(s) (—CH
2
—) in the above-mentioned groups may be substituted by (an) oxygen atom(s) (—O—) and —CH═CH— in all cases, and n denotes an integer of from 0 to 20.) is contained as the first component, at least one compound expressed by the general formulae II-a, II-b, II-c and II-d
(wherein, R
1
denotes an alkyl group having from 1 to 10 carbon atom(s), optional one or non-adjacent two or more than two methylene group(s) (—CH
2
—) in the above-mentioned groups may be substituted by (an) oxygen atom(s) (—O—) and —CH═CH— in all cases, and n denotes an integer of from 0 to 20.) is contained as the second component, and one or more than one compound(s) selected from the group of compounds expressed by the general formulae III-a, III-b and III-c
(wherein, R
2
denotes an alkyl group having from 1 to 10 carbon atom(s), optional one or non-adjacent two or more than two methylene group(s) (—CH
2
—) in the above-mentioned groups may be substituted by (an) oxygen atom(s) (—O—) and —CH═CH— in all cases, Z
0
denotes —COO— or —CH
2
CH
2
—, Z
1
denotes —C
2
CH
2
—, —COO— or a single bond, Q
1
denotes H or F, A
1
denotes trans-1,4-cyclohexylene, 1,4-phenylene or 1,3-dioxane-2,5-diyl, A
2
and A
3
denote each independently trans-1,4-cyclohexylene or 1,4-phenylene, and p, q and m each independently denote 0 or 1.) is contained as the third component.
(2) A liquid crystal composition described in the above-mentioned item (1), characterized in that the first component is from 3 to 50% by weight, the second component is from 3 to 40% by weight and the third component is from 10 to 60% by weight, all based on the total weight of the liquid crystal composition.
(3) A liquid crystal composition characterized in that at least one compound expressed by the general formulae I-a and I-b
(wherein, R
1
denotes an alkyl group having from 1 to 10 carbon atom(s), optional one or non-adjacent two or more than two methylene group(s) (—CH
2
—) in the above-mentioned groups may be substituted by (an) oxygen atom(s) (—O—) and —CH═CH— in all cases, and n denotes an integer of from 0 to 20.) is contained as the first component, at least one compound expressed by the general formulae II-a, II-b, II-c and II-d
(wherein, R
1
denotes an alkyl group having from 1 to 10 carbon atom(s), optional one or non-adjacent two or more than two methylene group(s) (—CH
2
—) in the above-mentioned groups may be substituted by (an) oxygen atom(s) (—O—) and —CH═CH— in all cases, and n denotes an integer of from 0 to 20.) is contained as the second component, one or more than one compound(s) selected from the group of compounds expressed by the general formulae III-a, III-b and III-c
(wherein, R
2
denotes an alkyl group having from 1 to 10 carbon atom(s), optional one or non-adjacent two or more than two methylene group(s) (—CH
2
—) in the above-mentioned groups may be substituted by (an) oxygen atom(s) (—O—) and —CH═CH— in all cases, Z
0
denotes —COO— or —CH
2
CH
2
—, Z
1
denotes —CH
2
CH
2
—, —COO— or a single bond, Q
1
denotes H or F, A
1
denotes trans-1,4-cyclohexylene, 1,4-phenylene or 1,3-dioxane-2,5-diyl, A
2
and A
3
denote each independently trans-1,4-cyclohexylene or 1,4-phenylene, and p, q and m each independently denote 0 or 1.) is contained as the third component, and at least one or more than one compound(s) selected from the group of compounds expressed by the general formulae IV and V, VI-a and VI-b
R
3
-(B)-Z
2
-(C)-R
4
  (IV)
(wherein, R
3
and R
4
denote each independently an alkyl group having from 1 to 10 carbon atom(s), optional one or non-adjacent two or more than two methylene group(s) (—CH
2
—) in the above-mentioned groups may be substituted by (an) oxygen atom(s) and —CH═CH— in all cases, B denotes trans-1,4-cyclohexylene, pyrimidine-2,5-diyl or 1,4-phenylene, C denotes trans-1,4-cyclohexylene or 1,4-phenylene, and Z
2
denotes —C≡C, —COO—, —CH
2
CH
2
—, —CH═CH—, —CF═CF— or a single bond.),
R
5
-(D)-Z
3
-(E)-Z
4
-(G)-R
6
  (V)
(wherein, R
5
denotes an alkyl group having from 1 to 10 carbon atom(s), optional one or non-adjacent two or more than two methylene group(s) (—CH
2
—) in the above-mentioned groups may be substituted by (an) oxygen atom(s) (—O—) and —CH═CH— in all cases, R
6
denotes an alkyl group, an alkoxy group or an alkoxymethyl group having from 1 to 10 carbon atom(s), D denotes trans-1,4-cyclohexylene or pyrimidine-2,5-diyl, E denotes trans-1,4-cyclohexylene or 1,4-phenylene in which one H at a branched position may be optionally substituted with F, G denotes trans-1,4-cyclohexylene or 1,4-phenylene, Z
3
denotes —CH
2
CH
2
— or a single bond, and Z
4
denotes —C≡C—, —COO— or —CH═C— or a single bond.),
(wherein, R
7
denotes an alkyl group having from 1 to 10 carbon atom(s), optional one or non-adjacent two or more than two methylene group(s) (—CH
2
—) in the above-mentioned groups may be substituted by (an) oxygen atom(

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