JPS59124978A - Nematic liquid crystal composition - Google Patents

Abstract

PURPOSE:To provide a nematic liquid crystal composition having excellent low temperature properties and suitable for dynamic driving, prepared by adding a specified liquid crystal compd. to a conventional nematic liquid crystal composition. CONSTITUTION:The nematic liquid crystal composition is prepared by adding a compd. of formula IV (where R5 and R6 are 2-7C straight-chain alkyl), e.g. a compd. of formula V, or a compd. of formula VI (where R8 and R9 are 2-8C alkyl), e.g. a compd. of formula VII, to a liquid crystal composition consisting of a compd. of formula I (where R1 and R2 are 1-8C straight-chain alkyl), a compd. of formula II (where R3 and R4 are 2-8C straight-chain alkyl) and a compd. of formula III (where R7 is 2-8C straight-chain alkyl). The composition has a wide liquid crystal temperature range inherent to conventional liquid crystal composition, is excellent in low temperature and electrooptical properties and is suitable for dynamic driving.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a nematic liquid crystal composition, particularly a liquid crystal composition suitable for dynamic driving.
It is primarily used as a display element material for digital displays, watches, etc. The systems used in these display elements are screw nematic system (TN system), i#l
There are many types, such as the target scattering method and the guest-host method, but among them, the TN method is the most widely used. Furthermore, in this TN system, in order to display a large amount of information with one liquid crystal cell, it is necessary to provide a large number of pixels (75 steps). A liquid crystal cell is used, in which a group of band-shaped transparent electrodes are made orthogonal to each other, and the intersection of the scanning electrode group, the signal electrode group, and the heel electrode is used as a t pixel, that is, a matrix liquid crystal cell. There is a driving method, that is, a dynamic driving method. In this case, when the number of scanning electrodes is increased to increase the number of pixels, the number of time divisions also increases accordingly, and the difference between the effective voltages applied to the selected electrodes and the non-selected electrodes becomes relatively small. Therefore, in order to increase the number of pixels and obtain the same contrast as in Japan, the characteristic conditions required of liquid crystal materials have become more severe. That is, (1) the rise 9 of the voltage-contrast curve is steep;

■ Possible to drive at low voltage.

Furthermore, in recent years, since liquid crystal displays have been applied in various fields, the following conditions have become essential in addition to the above conditions. That is, ■ The response speed is fast.

■ Wide operating temperature range centered around room temperature.

etc.

Among the conventionally known liquid crystal compositions, a nematic liquid crystal composition (Japanese Patent Application No. 56-121998) consisting of an azoquizo compound and an ester compound having electric field orientation is
Of the above conditions, it is considered to be the most excellent as it satisfies all of the conditions (1), (2), and (3). (7) However, its nematic liquid crystal temperature range cannot be said to be sufficient.On the other hand, it contains the above-mentioned - compound and the above-mentioned general formula R3be>N=
A nematic liquid crystal composition was invented (a patent application has been filed by the present applicant) containing a compound represented by No.
While having electro-optical properties of i″ (conditions ■, ■, ■),
It became possible to obtain a wide nematic liquid crystal temperature range (condition ■). However, even in these inventions,
There are limits to electro-optical properties. Therefore, the current trend is to find a nematic liquid crystal composition that is more suitable for dynamic driving.

In view of the above circumstances, it is an object of the present invention to provide a nematic liquid crystal composition that satisfies condition (1) and has better strength characteristics than conditions (2) to (2).

(R1, R2 are linear alkyl groups having 2 to 8 carbon atoms), and the general formula R3 is N=N÷R4 (R31τ R4 is a straight chain alkyl group having 2 to 8 carbon atoms); Contains at least one kind of compound represented by straight chain alkyl,
7 -o-0-o6c N (R 7 1'j:
A compound (hereinafter referred to as
(abbreviated as CHA liquid crystal in the text) -41cu, a compound represented by the general formula Rs -@-Q-o-Ro (Ra 5R9U represents a linear alkyl group having 2 to 8 carbon atoms) (hereinafter referred to in the text) (abbreviated as POH liquid crystal herein) ← Claims 1 and 2)
, ma1ξ are each one or more types (Claim 3)
A nematic liquid crystal composition containing The nematic liquid crystal composition of the present invention not only secures the wide liquid crystal temperature range of conventional liquid crystal compositions, but also has unprecedented electro-optical properties, and has superior properties for dynamic driving. .

Hereinafter, specific characteristics of the nematic liquid crystal composition of the present invention will be shown together with practical examples.

In the examples, the voltage when the contrast changes by 10% when viewed from the vertical direction of the cell is VIO-90.
', the voltage when the contrast changes by 90° from the same direction is v9ochi・s0°, and the voltage when the contrast changes by 10% when the cell is pushed by 40°fc from the vertical direction to the clear viewing direction is vtos.・Set at 50°. The steepness (β) of the voltage-contrast curve and the change in threshold voltage I#l(α) due to changes in viewing angle are expressed by the following equations, and the γ value that takes into account both the steepness and viewing angle dependence is expressed by the following equation.

Furthermore, from the state in which a voltage Vlochi·90° was applied to Q), which represents the response speed of the liquid crystal cell, when viewed from the vertical direction of the cell, a voltage V90chi·io'k was applied to increase the force.・The time required for the contrast to change by 90% is 'l'' O-N, and after lowering the voltage from the state where the voltage V2O is applied at 90 degrees to the voltage IV at 90 degrees, the contrast is still 90%. The time required for the change is expressed as T OFF .

Specific examples of the nematic liquid crystal composition of the present invention will be shown below as examples.

Table 1 (1, Examples 1 and 2 in the present invention (in the table, B, O
) and Comparative Example 1 (A in the table), and the composition ratios are expressed in mulch.

Example 1. Comparative Example 1 Comparative Example 1 is a conventional nematic liquid crystal compound, and CI
Does not include A liquid crystal or POH liquid crystal.

The electro-optical properties of this material are α at a cell thickness of 4.6μ.
The value is 1.16, the β value is 1.19, and the γ value is 1.39. (Response speed TON and To y +r are each 49
(millisecond, 85 milliJ seconds) Also, its low-temperature properties are stable at -20°C for more than a month, and its high-temperature properties are stable up to around 80°C, and it has a relatively wide nematic liquid crystal range.

On the other hand, in Example 1, two O)IA liquid crystal components were added to Comparative Example 1, and the content was made into a tile so that the content was 10 moles of the total composition ratio, and was patented. This is an example of the nematic liquid crystal composition I according to claim 1. As for its electro-optical characteristics, when the cell thickness was 4.4μ, the α value was 1.14, which is a smaller value than Comparative Example 1. Therefore, the β value is 1.19, which is equivalent to Comparative Example 1, but the γ value i
d was made quite small at 1.36. Excellent response speed T
ON and 'I' OFF are 45 milliseconds and 78 milliseconds, respectively, which are equivalent compared to Comparative Example 1. Also, the temperature range is from -20℃ to around 80℃,
It has the same nematic liquid crystal temperature range as Comparative Example 1.

From the above results, it is clear that the addition of CHA liquid crystal can improve the α value without changing the nematic liquid crystal temperature range and β value. That is, the nematic liquid crystal composition according to claim 1 (1) is suitable for dynamic driving and has fce properties equivalent to those of conventional compositions, and further has a small α number, so it has low viewing angle dependence and can be used in a wide range of clear viewing directions. It can be said that it has excellent fc characteristics not seen before.

Example 2 In Example 2, two components of PC)T liquid crystal were added to Comparative Example 1, and the content thereof was adjusted to be 10 moles of the total composition ratio, and the content was adjusted to be 10 moles of the total composition ratio. This is an example of the nematic liquid crystal composition of item 2.

As for its electro-optical properties, when cell I#a is 6μ, the α value is 1.15, which is between Example 1 and Comparative Example 1.

A talented woman with a β value of 1.18, which is also smaller than Comparative Example 1.
Therefore, the γ value is also quite small at 1.35, i*TON
and TOFF are 47 ms and 86 ms, respectively;
It is equivalent to Comparative Example 1. The nematic liquid crystal temperature range is also stable from around -20°C to around 80°C. That is, the nematic liquid crystal composition described in claim 2 is more suitable for dynamic screen operation than conventional compositions.

Example C4H9C')N-N-)04He 10.
0τ (same below weight) C5H11 (ToN = NbetC3Ht+
14゜5τ C6H1r0→I=N-o-06H1313,4C7H
u5-o-N-=N-o-C7Hu5 12
．． 0τ C2H5-o-C-0-C1-CN
6.4j 04 T(+,→■hiC-0-◎←C!N
7.11 C! 5H1+ -4D-C-0→[Stock]←OC5Hu
4.11)゛Cs Hp-mother 〇-〇(Q)-〇-c,, HI3
4.51 Cs Hu -o-o-o-c,, Hu3
5.8Cs Hp publication (Too-07H15
A nematic liquid crystal composition consisting of 14 components of 5 and 9 was prepared and designated as Example 5. This product was stable on the high temperature side up to around 80℃, which is the same as the conventional one, but on the low temperature side -20℃.
At temperatures below .degree. C., it exhibits a smectic phase, and it is difficult to drive it at around -20.degree. However, its electro-optical characteristics have an α value of 1.14 at a cell thickness of 4.9μ,
The β value is 1.18, and the α value is that of Example 1, and β
It is recognized that the value is the same as that of Example 2, and is extremely superior. That is, in Example B, although the low-temperature properties are not sufficient, it is possible to prepare one with even better low-temperature properties by changing the composition ratio. On the other hand, it has excellent electro-optical properties and can be said to be a nematic liquid crystal composition more suitable for digital drive than conventional ones.

Example 4 In the present invention, as an example showing the influence of the composition ratio on low-temperature properties, the compositions shown in Table 2-0 were prepared, and the compositions were further mixed to form a nematic material. A liquid crystal composition was prepared and its low temperature characteristics were observed.

The composition and low temperature properties of these nematic liquid crystal compositions are shown in Tables 2-1, 2-29 and 2-3. Table 2-1 to Table 2
-6, each nematic composition was represented by a serial number, and each composition was shown in weight % of groups A to G.

Low temperature characteristics are -20℃ and -30℃ when sealed in a cell.
When left in a constant temperature bath at ℃ for about 100 hours, those that showed no change at all and were stable are marked with an ○, those that precipitated are marked with an X, and those that exhibited a cross-smectic phase are marked with an S. .

(1) The nematic liquid crystal composition shown in Table 2-1 is an example of the nematic liquid crystal composition described in claim 1 of the present invention. That is, 4 azoquine compounds (group A)
5-65% by weight.

Ester-azoxy (group B) j710-60 weight ratio, relatively long alkyl group cHc liquid crystal (group 0) '1o-30
OHO liquid crystal with relatively short alkyl group (D group)
The content was arbitrarily changed from 0 to 30% by weight, each by 10% by weight, and the ester compound having positive dielectric anisotropy was prepared and measured at a uniform concentration of 15% by weight.

In Table 2-1, the nematic liquid crystal compositions represented by numbers 2 to 7 were stable even at -30°C.

Table 2-O Group A c4H! ]Pe> N=N-o-04H925,6
(Similar to weight disturbance and below) C5H, Tomi-Q-N=N- (Friend>OsH+ □
5 Z 1C6e (13-o-N
-N-o-C6H1322,507HI5-=G-N=
N→>a7nt,, 16.8B group C4
H9÷CO', jQCN=N-(Q)-05H((25
,01 OsH+ c-0-Q-N=brg-c4He
25.01 C3Ht t -@-C-0-((3-N=N÷C5H
tt, 25.01 C6HI3÷C-0-C)) N:N-o-06H132
5,01 0 group 04 H9÷C-0-Q-0-as H,333,
4ru Os Htt -o-a-o→洲0-05 Htt
33.31 05Htt÷a-ope))O-c,, I(1333,
31 Group D C3H7÷Co-o-o C! 2H51Q, 1
1 C3H7 publication LO-0ite OC4H926, 31 04H9-/JJ)-C-o-O+oc Hs20
．． 51 C4H9 published C-0be)) o-02H720,61 C3H11 published C-0÷○-0B3 22.51 Group B csI(tt Hammer H(o-C5Htt
33.4CsHtt-@-o-0-06H133A30
s Hn -@-o-o c7Ht5
33.3FW-C3H7)H snoring○-02H543,5C
3H7BeTJ-'D)-o-04Hs23. qc4H
g bell (zu→-C2-32,6 G group 0zHs-'0j=0-o-o-aN' 50
．． 01 C< Hs -G-c-o-Ω=cn
50.01 Table 2-1 Table 2-2 Table 2-6 However, the nematic liquid crystal compositions numbered 8, 9 and 15 (r-l, -20 The nematic liquid crystal composition No. 16.17 containing 65% by weight of the lyazoxy compound (group A) was precipitated at -30°C.Similarly,
No. 1 enriched with 55% by weight of azoquine compounds (group A)
Nematic liquid crystal compositions 0 to 14 were stable at -20°C, but precipitated at -30°C.

From the above results, in this example, 55% by weight of the azoquine compound gold-containing compound was
When the azoquine compound was added in a content not exceeding 30%, a liquid crystal composition with the lowest temperature characteristics was obtained. It can be seen that the length or shortness of the alkyl group of the 0HOi crystal added at the time of shredding does not have a large effect on the low temperature characteristics.

However, the nematic liquid crystal 1 compound containing a total of 30 CI-I C compounds with long alkyl groups is -2
DC shows a smectic phase due to sweat and is an exception.

(2) Nema-Dikku product composition core 1 shown in Table 2-2,
This is an example of a nematic liquid crystal composition according to claim 2 of the present invention. That is, the azoquine compound (group A) was mixed with 45 to 65 molecules, and the ester-azoxylated compound (B
ffl ) ' has a relatively long alkyl group PC with a weight of 10 to 60 φ! Hp products (E group) each with O to 60 heavy needles,
Ester compounds (group G) having positive dielectric anisotropy were prepared and measured in 15 weight groups, with the content arbitrarily changed in 10 weight groups.

Nematic liquid crystal composition No. 25.26 containing 30% by weight of an ester-azoquine compound (contains a total of 55% by weight of the azoquine compound (group A) precipitated at -20°C and cleaved, and 1% by weight of the ester-azoquine compound) The nematic liquid crystal compositions numbered 30.31 containing azoquine compound (group B) i20% by weight and number @32°55 containing 65% azogine compound by weight were precipitated at -20°C. , these trends are almost similar to (1) of Example 4. However, in addition to the nematic liquid crystal composition No. 18, the nematic liquid crystal compositions No. 22, 27.
The nematic liquid crystal composition of No. 32 also exhibits a smectic phase, and in this example, PCH with a relatively long alkyl group
This shows that liquid crystals (group E) are more likely to exhibit a smectic phase than CHC liquid crystals (group D).

From the above results, in this example as well, a nematic liquid crystal composition with excellent low temperature properties can be obtained in the same manner as in Example 4 (1).

However, in order to avoid the appearance of a smectic phase, either the alkyl group should be relatively long (the content of nPC! It is necessary to make life short.

(3) The nematic liquid crystal composition shown in Tables 2-3 is an example of the nematic liquid crystal composition described in claim 6 of the present invention. That is, azoquine compounds (group A)
45-55% by weight of ester-azoxy compounds (group B), 10-20% of total type, OHC with relatively long alkyl groups
0 to 20% by weight of liquid crystal (Group 0), 0 to 20% by weight of OHC liquid crystal with relatively short alkyl groups (Group D), and 0 to 20% of PEH liquid crystal with relatively long alkyl groups (Group E).゛Reception,
0 to 2 pCH liquid crystals (F group) with relatively short alkyl groups
The contents were arbitrarily changed by 0% by weight and 10% by weight, and the ester compounds having all positive dielectrics were prepared and measured at a uniform concentration of 15% by weight.

Azoxy compounds (group A) and azoxy-ester compounds (group B), CHC with relatively long alkyl groups! No. 64, which is a nematic liquid crystal composition containing liquid crystal (Group 0) and POH liquid crystal with a relatively long alkyl group (Group E), totaling 85% by weight.
Each of ゜36 + 44146 is ゛C at -20℃
It exhibits a smectic phase, and the azoquine compound t 55
Lm: Nematic liquid crystal composition containing No. 46~
Each of No. 49 precipitated at -30°C. However, other nematic liquid crystal compositions were stable even at -30°C.

As mentioned above, in the nematic liquid crystal composition of the present invention, -2
Under severe conditions of 0°C to -30°C, precipitation and appearance of smectic phase were observed in some cases;
Compared to conventional azoxy compounds and nematic liquid crystal compositions having positive dielectric anisotropy, which precipitate at temperatures of 0°C to -15°C, the nematic liquid crystal composition of the present invention has remarkable low-temperature properties. It shows that it is superior.

that's all Applicant: Suwa Seikosha Co., Ltd.

Claims (1)

[Scope of Claims] ○ 0 (in the formula, R+ and R2 represent a straight-chain alkyl group having 1 to 8 carbon atoms) and contains at least one or more of the Kinwaki Kuotsu compounds, and
General formula R2-ΩtN2N-g-R4 (in the formula, R,,
, R4 represents a straight-chain alkyl group having 2 to 8 carbon atoms);
Contains at least one compound of the general formula 1. (wherein R5 and R6 represent a straight-chain alkyl group having 2 to 7 carbon atoms), and
It is characterized by containing at least one compound represented by the general formula: A nematic liquid crystal composition, containing at least one compound represented by:
Contains at least one compound represented by the above general formula R3be>N=N+R4, and has the general formula R8-e-
o-O-R9 (in the formula, Rs and R9 represent a straight-chain alkyl group having 2 to 8 carbon atoms); A nematic liquid crystal composition characterized by a backing metal comprising at least one compound represented by 0(0)-ON1. contains at least one kind of compound represented by the above general formula R3betoN=Nbe>R<, and contains at least one kind of compound represented by the above general formula R5÷
0-014G-Rs1 Contains at least one kind of compound represented by the above general formula Rs -@-o-o -, contains at least 1$iJ of a compound represented by the above general formula R9, and contains the above general formula R7 group 0-0 -0*ON1 A nematic liquid crystal composition characterized by a semimetal containing at least one type of compound that is resistant to oxidation.