JPH0657252A - Liquid crystal composition - Google Patents

Abstract

PURPOSE:To obtain a liquid crystal composition improved in various properties such as the N-I point and refractive anisotropy by adding a 4-alkyl- or 4-alkoxy- benzoic acid to a liquid crystal composition. CONSTITUTION:The liquid crystal composition contains at least one 4-alkyl- or 4-alkoxy-benzoic acid of the formula (wherein R is a 1-12C alkyl or an alkoxy). Examples of the alkyl or alkoxy groups are linear or branched alkyl groups, such as methyl, ethyl, n-butyl and 1-methylbutyl, and alkoxy groups derived therefrom. When the alkyl or alkoxy group is branched, it may be optically active one. Thus, this compound can give a liquid crystal composition of a high N-I point and high refractive anisotropy. It scarcely causes an increase in the viscosity of a liquid crystal composition, and what is more, it sometimes causes a decrease in the viscosity of the composition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nematic liquid crystal composition used for a liquid crystal display device, and more particularly to a nematic liquid crystal composition containing 4-alkyl or alkoxybenzoic acid.

[0002]

2. Description of the Related Art With the widespread use of liquid crystal display elements utilizing the electro-optical effect of liquid crystals, there has been a demand for liquid crystals having characteristics suitable for these applications. The following characteristics are required for the liquid crystal to be used.

(1) The liquid crystal has high chemical stability. (2) It exhibits a liquid crystal phase in a wide temperature range including room temperature. (3) Good response in a wide temperature range. (4) Good compatibility with the drive circuit. (5) The optical anisotropy has a value that meets the optical requirements.

No single liquid crystal compound satisfying all of these characteristics is known at present, and it is attempted to satisfy the above various characteristics as a liquid crystal composition in which several kinds of liquid crystal compounds are mixed. The current situation.

The liquid crystal compound used for the preparation of this liquid crystal composition is a phenyl ester compound of a cyclic carboxylic acid such as alkyl or alkoxybenzoic acid or alkylcyclohexanecarboxylic acid, an aromatic nitrile compound, an alkyl or alkoxy biphenyl or terphenyl derivative. , Alkylcyclohexanecarboxylic acid and the like are known.

However, these conventionally known liquid crystal compositions have various drawbacks such as an inappropriate temperature range showing a liquid crystal phase and a slow response speed, and are not practically satisfactory. .

[0007]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to improve various properties of conventionally known liquid crystal compositions, and as a result, 4-alkyl or alkoxybenzoic acid was added to the liquid crystal composition. The present invention has been completed by discovering that a liquid crystal composition having excellent properties can be obtained by blending them.

That is, the present invention provides the following chemical formula 4 (same as chemical formula 1).
The present invention provides a nematic liquid crystal composition containing at least one of 4-alkyl or alkoxybenzoic acid represented by the general formula (I).

[Chemical 4] (In the formula, R represents an alkyl group or an alkoxy group having 1 to 12 carbon atoms.)

In the compound represented by the above general formula (I), the alkyl or alkoxy group having 1 to 12 carbon atoms represented by R is methyl, ethyl, propyl,
Isopropyl, n-butyl, isobutyl, n-pentyl, 1-methylbutyl, 2-methylbutyl, 3-methylbutyl, n-hexyl, 1-methylpentyl, 2-methylpentyl, 3-methylpentyl, 4-methylpentyl, n- Derived from linear or branched alkyl groups such as octyl, 1-methylheptyl, 2-methylheptyl, 2-ethylhexyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, and these alkyl groups. Examples thereof include an alkoxy group, and when the alkyl group or the alkoxy group is branched, it may be an optically active group.

Next, 4- which constitutes the liquid crystal composition of the present invention
Liquid crystal temperature range of alkyl or alkoxy benzoic acid (M
R) is shown. R = CH ₃ MR (° C.) = 182, R = C ₂ H ₅ MR (° C.) = 113, R = nC ₃ H ₇ MR (° C.) = 143, R = nC ₄ H ₉ MR (° C.) = 99- 113, R = nC ₅ H ₁₁ MR (° C) = 88-126, R = nC ₆ H ₁₃ MR (° C) = 97-114, R = nC ₇ H ₁₅ MR (° C) = 101-120, R = nC ₈ H ₁₇ MR (° C) = 99-112, R = nC ₉ H ₁₉ MR (° C) = 98-115, R = nC ₁₀ H ₂₁ MR (° C) = 94-109, R = CH ₃ O MR (° C ) = 184, R = C ₂ H ₅ O MR (° C.) = 196, R = nC ₃ H ₇ O MR (° C.) = 145-154, R = nC ₄ H ₉ O MR (° C.) = 147-160, R = nC ₅ H ₁₁ O MR (° C.) = 124-151, R = nC ₆ H ₁₃ O MR (° C.) = 105-153, R = nC ₇ H ₁₅ O MR (° C.) = 92-146, R = nC ₈ H ₁₇ O MR (° C) = 101-147, R = nC ₉ H ₁₉ O MR (° C) = 94-143, R = nC ₁₀ H ₂₁ O MR (° C) = 97-142, R = nC _{11 H 23 O MR (℃) =} 95-137

The present invention is represented by the above general formula (I).
At least one of alkyl or alkoxybenzoic acid relates to a nematic liquid crystal composition obtained by blending a conventionally known nematic liquid crystal compound or a mixture thereof, and the above nematic liquid crystal compound or a mixture thereof includes, for example, Examples thereof include compounds represented by the following chemical formula 5 and mixtures thereof.

[0012]

[Chemical 5] (In the formula, R ₁ and R ₂ are each a hydrogen atom, a halogen atom, a hydroxyl group, a nitro group, a cyano group, and a carbon atom number of 1 to 12.
Alkyl group, C1-C12 alkoxy group, C2-C12 alkenyl group, C2-C12
Represents an alkenyloxy group, a carboxy group or an alkoxycarbonyl group having an alkyl group having 1 to 12 carbon atoms, R represents a hydrogen atom or a halogen atom, and X represents
-O-, -CO-O-, -O-CO-, -CH ₂ O-, -OCH-, -CH ₂ CH _2- , -C
H = CH- or -C≡C- and rings A and C each represent a benzene ring, a transcyclohexane ring or a pyrimidine ring, ring B represents a benzene ring or a transcyclohexane ring, and a, b and c each represent 1 ~ 3 is shown. When the same symbol is present in the same molecule, they may be the same or different. )

Therefore, specific examples of the nematic liquid crystal compound include the compounds shown in Chemical formula 6 below.

[0014]

[Chemical 6]

In order to obtain a liquid crystal composition having good characteristics,
Among these compounds, it is preferable to use a mixture of a compound R ₂ is a cyano group (an aromatic nitrile compound) or R ₂ comprises a compound which is a cyano group, in particular the following Chemical Formula 7
It is preferable to use at least one compound represented by the general formula (II) (same as the chemical formula 2) and / or the general formula (III) of the following chemical formula 8 (the same as the chemical formula 3).

[0016]

[Chemical 7] (In the formula, R ₁ represents an alkyl group or an alkoxy group having 1 to 12 carbon atoms.)

[0017]

[Chemical 8] (In the formula, R ₂ represents an alkyl group having 1 to 12 carbon atoms.)

Further, in the nematic liquid crystal of the present invention,
The compounding ratio of the alkyl or alkoxy benzoic acid and the nematic liquid crystal compound is not particularly limited, but generally, the ratio of the 4-alkyl or alkoxy benzoic acid compound to the total liquid crystal composition is 1 to 80% by weight. It is preferable to use so that

The nematic liquid crystal composition of the present invention may be blended with a non-liquid crystal compound having a chemical structure similar to that of the nematic liquid crystal compound within the range not impairing the object of the present invention, and in some cases, it may be incorporated. By blending such a non-liquid crystal compound, the characteristics of the liquid crystal composition can be further improved.

[0020]

The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited by the following examples.

Example 1 A nematic liquid crystal composition of the present invention having the composition shown in Table 1 below was prepared, and the NI point of the liquid crystal composition, the viscosity at 20 ° C. (η; centipoise), and the dielectric constant at 25 ° C. were measured. Anisotropy (Δε), refractive index anisotropy at 25 ° C. (Δn), and elastic constant at 25 ° C. were measured. The results are shown below, and were extremely excellent in practical use. NI point: 80 ° C., η: 43.6, Δε: 6.1, Δ
n: 0.127, elastic constant: 1.28

[0022]

[Table 1]

Comparative Example 1 Regarding the nematic liquid crystal composition having the composition shown in Table 2 below, as in Example 1, the NI point of the liquid crystal composition, the viscosity of the liquid crystal composition, the anisotropy of the dielectric constant, and the refraction were measured. The anisotropy of the rate was measured. The results were as follows. NI point: 68 ° C., η: 47.0, Δε: 9.0, Δ
n: 0.113

[0024]

[Table 2]

Comparing the results of Example 1 and Comparative Example 1, by adding the alkylbenzoic acid represented by the above general formula (I), the NI point was increased, the viscosity was decreased, and the refractive index was changed. Increased directionality is observed.

Example 2 A nematic liquid crystal composition of the present invention having the composition shown in Table 3 below was prepared, and in the same manner as in Example 1, the NI composition of the liquid crystal composition was measured.
The point, the viscosity of the liquid crystal composition, the anisotropy of the dielectric constant, the anisotropy of the refractive index, and the elastic constant were measured. The results are shown below, and were extremely excellent in practical use. NI point: 77 ° C., η: 24.7, Δε: 10.1, Δ
n: 0.131, elastic constant: 1.30

[0027]

[Table 3]

Example 3 A nematic liquid crystal composition of the present invention having the composition shown in Table 4 below was prepared, and in the same manner as in Example 1, the liquid crystal composition had an NI composition.
The point, the viscosity of the liquid crystal composition and the anisotropy of the refractive index were measured. The results are shown below, and were extremely excellent in practical use. NI point: 66 ° C., η: 26.4, Δn: 0.126

[0029]

[Table 4]

Comparative Example 2 With respect to the nematic liquid crystal composition having the composition shown in Table 5 below, in the same manner as in Example 1, the NI point of the liquid crystal composition, the viscosity of the liquid crystal composition, the anisotropy of dielectric constant, and the refraction The anisotropy of modulus and elastic constant were measured. The results were as follows. NI point: 52 ° C., η: 23.1, Δε: 11.
6, Δn: 0.119

[0031]

[Table 5]

Comparing the results of Examples 2 and 3 with Comparative Example 2, the addition of the alkylbenzoic acid represented by the above general formula (I) increases the NI point and increases the anisotropy of the refractive index. It is observed that the viscosity is increased and the increase in viscosity is extremely small.

Example 4 A nematic liquid crystal composition of the present invention having the composition shown in Table 6 below was prepared, and in the same manner as in Example 1, the liquid crystal composition had an NI composition.
The point, the viscosity of the liquid crystal composition, the anisotropy of the dielectric constant, the anisotropy of the refractive index, and the elastic constant were measured. The results are shown below, and were extremely excellent in practical use. NI point: 65 ° C., η: 32.2, Δε: 6.1, Δ
n: 0.116, elastic constant: 1.17

[0034]

[Table 6]

Example 5 A nematic liquid crystal composition of the present invention having the composition shown in Table 7 below was prepared, and, in the same manner as in Example 1, the liquid crystal composition had a NI composition.
The point, viscosity, dielectric anisotropy, refractive index anisotropy and elastic constant were measured. The results are shown below, and were extremely excellent in practical use. NI point: 73 ° C., η: 29.6, Δε: 9.9, Δ
n: 0.129, elastic constant: 1.16

[0036]

[Table 7]

Example 6 A nematic liquid crystal composition of the present invention having the composition shown in Table 8 below was prepared, and in the same manner as in Example 1, the liquid crystal composition had an NI composition.
The point, viscosity, dielectric anisotropy, refractive index anisotropy and elastic constant were measured. The results are shown below, and were extremely excellent in practical use. NI point: 61 ° C., η: 29.0, Δε: 9.1, Δ
n: 0.114, elastic constant: 1.47

[0038]

[Table 8]

Example 7 A nematic liquid crystal composition of the present invention having the composition shown in Table 9 below was prepared, and in the same manner as in Example 1, the liquid crystal composition had an NI composition.
The point, viscosity, dielectric anisotropy, refractive index anisotropy and elastic constant were measured. The results are shown below, and were extremely excellent in practical use. NI point: 78 ° C., η: 31.8, Δε: 9.8, Δ
n: 0.141, elastic constant: 1.20

[0040]

[Table 9]

Example 8 A nematic liquid crystal composition of the present invention having the composition shown in Table 10 below was prepared, and in the same manner as in Example 1, the liquid crystal composition had an NI composition.
The point, viscosity, dielectric anisotropy, refractive index anisotropy and elastic constant were measured. The results are shown below, and were extremely excellent in practical use. NI point: 65 ° C., η: 31.9, Δε: 10.0, Δ
n: 0.137, elastic constant: 1.81

[0042]

[Table 10]

As is clear from the results of the examples, 4-
By adding alkyl or alkoxybenzoic acid, not only the NI point of the liquid crystal composition can be increased and the anisotropy of the refractive index can be increased, but also the viscosity of the liquid crystal composition is hardly increased. In some cases, the viscosity can be reduced. As described above, the liquid crystal composition of the present invention is a nematic liquid crystal for a TN cell, a guest.
It is extremely excellent as a host liquid crystal for a host type display device or a liquid crystal for a time division drive type liquid crystal display device.

[0044]

The liquid crystal composition of the present invention has
The characteristics of the liquid crystal composition such as the NI point and the anisotropy of the refractive index are improved.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshihiro Shibata 136-49-3-104 Nara-machi, Omiya-shi, Saitama Prefecture (72) Masaki Kimura 1019-49 Shimoyasumatsu, Tokorozawa-shi, Saitama Inventor Yukari Shinada 9-10-11-404 Tokiwa, Urawa City, Saitama Prefecture

Claims (4)

[Claims] 1. A compound represented by the following general formula (I):
A nematic liquid crystal composition comprising at least one kind of alkyl or alkoxy benzoic acid. [Chemical 1] (In the formula, R represents an alkyl group or an alkoxy group having 1 to 12 carbon atoms.) 2. A compound represented by the general formula (I) of the above chemical formula 1
The nematic liquid crystal composition according to claim 1, which contains an aromatic nitrile compound together with an alkyl or alkoxy benzoic acid. 3. The nematic liquid crystal composition according to claim 2, wherein the aromatic nitrile compound is a compound represented by the following general formula (II). [Chemical 2] (In the formula, R ₁ represents an alkyl group or an alkoxy group having 1 to 12 carbon atoms.) 4. The nematic liquid crystal composition according to claim 2, wherein the aromatic nitrile compound is a compound represented by the following general formula (III). [Chemical 3] (In the formula, R ₂ represents an alkyl group having 1 to 12 carbon atoms.)