JP2000044955A - Dichroic dye composition, liquid crystal composition using the same, and liquid crystal display device - Google Patents

Abstract

(57) [Problem] To provide a dark gray to black dichroic dye composition having contrast characteristics and light stability. SOLUTION: A dichroic dye composition containing one or more dichroic dyes from the group (A) and one or more dichroic dyes from the group (B). Group (A): (I) and (II) Embedded image Group (B): (III) and (IV) Embedded image

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal composition used for a display device and the like and a liquid crystal device using the same, and more particularly to a guest-host type liquid crystal composition used for a reflection type liquid crystal display device.

[0002]

2. Description of the Related Art A guest-host type liquid crystal device using a guest-host type liquid crystal composition in which a dichroic dye is mixed with a host liquid crystal material does not necessarily require a polarizer. Because of its excellent viewing angle and brightness, it has attracted attention especially for reflective displays used in portable information devices.

The display quality such as the contrast of the guest-host type liquid crystal device is determined by the dichroic or order parameter of the dichroic dye contained in the guest-host type liquid crystal composition to be used, and the coloring density of the dichroic dye. High order parameters to correlate directly with
In addition, a guest-host type liquid crystal composition having a high coloring density is required. In particular, recently, a guest-host type liquid crystal composition using a host liquid crystal composition such as a fluorine-based liquid crystal, which can be used for an active driving liquid crystal display device and has a high order parameter and a high coloring density, has been demanded.

On the other hand, a reflection type liquid crystal display device, which performs display by reflecting ambient light incident from outside without using a backlight, is considered to be used outdoors and is particularly resistant to light such as direct sunlight. Therefore, high charge retention characteristics in active driving, that is, electrical characteristics such as a voltage retention ratio are required. However, azo dyes conventionally used in guest-host type liquid crystal compositions generally show high order parameters, but are inferior to light in stability compared to anthraquinone dichroic dyes. There is a problem that azo dyes that can be practically used due to a decrease in voltage holding ratio are very limited.

Although anthraquinone dyes have better electrical properties to light than azo dyes, the order parameters of the dyes alone tend to be inferior to those of azo dyes. Due to problems such as power, there has been a problem that a higher addition concentration, that is, solubility is required than that of the azo dichroic dye. Furthermore, even with an azo dye having relatively excellent stability upon exposure to light, it has been difficult to achieve both high dichroism, which is essential for realizing high contrast characteristics, and high solubility in a host liquid crystal material.

Further, a composition having a hue such as black, brown or dark blue in which a plurality of dyes are blended is used in a light absorption wavelength region where the order parameter of each dye to be blended is far from the main absorption wavelength (λmax). In order to decrease, the order parameter is reduced in the wavelength region where the light absorption spectrum of each dichroic dye overlaps, and in a composition such as the above black mixed with dichroic dyes of various structures, the guest-host type liquid crystal composition This is a cause that the whole contrast cannot be sufficiently obtained. In particular, in a guest-host type liquid crystal composition having a black hue, this problem is inconsistent with the reduction in contrast due to the overlapping of the absorptions of the respective dyes and the smoothness of the absorption spectrum required for the color tone. Therefore, it was difficult to realize a guest-host type liquid crystal composition exhibiting higher order parameters and high light stability.

The present invention provides a guest host having a hue such as black, brown, or dark blue for the purpose of performing multicolor display such as multicolor or full color by using a monocolor display or a micro color filter with good visibility. An object of the present invention is to provide a guest-host type liquid crystal composition exhibiting high order parameters and high light stability when using a liquid crystal composition of the type.

[0008]

SUMMARY OF THE INVENTION The present inventors have
The guest-host liquid crystal composition obtained by combining a specific dichroic dye, as a result of intensive studies to solve the above-described problem of the decrease in contrast in the guest-host liquid crystal composition obtained by blending a plurality of dichroic dyes, It has been found that the present invention has excellent contrast characteristics and excellent stability such as light fastness, and has completed the present invention.

That is, the gist of the present invention is characterized in that the dichroic dye composition contains at least one dichroic dye represented by the following groups (A) and (B) from each group. Present in dichroic dye compositions. (A) Group Azo dichroic dyes represented by the following general formulas [I] and [II]

[0010]

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(Where:

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Are each independently:

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Or

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Wherein R ¹ and R ² each independently represent a hydrogen atom or a halogen atom which may have 1 carbon atom.
12 alkyl group, a halogen atom optionally substituted alkoxy group having 1 to 12 carbon atoms, an alkoxyalkyl group or a halogen atom having 2 to 12 carbon atoms which may be substituted by a halogen atom, R ³ , R ⁴ each independently represent a hydrogen atom, a methyl group, a methoxy group, a halogen atom or a fluoromethyl group, and R ³ and R ⁴ may be linked to each other to form an aliphatic ring or an aromatic ring. )

[0015]

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(In the formula, R ⁵ and R ⁶ each independently represent a carbon atom which may be substituted with a hydrogen atom or a halogen atom.
Represents an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms which may be substituted with a halogen atom, an alkoxyalkyl group having 2 to 12 carbon atoms optionally substituted with a halogen atom, or a halogen atom. )

Group (B) Azo dichroic dyes represented by the following general formulas [III] and [IV]

[0018]

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(Where:

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Are each independently

[0021]

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Or

Embedded image

Wherein R ⁷ and R ⁸ each independently represent a hydrogen atom or a halogen atom which may have 1 carbon atom.
Represents an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms which may be substituted with a halogen atom, an alkoxyalkyl group having 2 to 12 carbon atoms optionally substituted with a halogen atom, or a halogen atom. )

[0024]

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(Where:

Embedded image Is

[0026]

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Or

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R ⁹ represents a hydrogen atom, an alkyl group having 1 to 12 carbon atoms which may be substituted by a halogen atom, an alkoxy group having 1 to 12 carbon atoms which may be substituted by a halogen atom, a halogen atom Represents an alkoxyalkyl group having 2 to 12 carbon atoms which may be substituted or a halogen atom. The present invention resides in a guest-host type liquid crystal composition using the dichroic dye composition and a host liquid crystal. Further, the present invention resides in a liquid crystal display device using the guest-host type liquid crystal composition.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. The dichroic dye composition of the present invention contains at least one dichroic dye from Group (A), which is a yellow-red dye, and at least one type from Group (B), which is a blue dye. Wherein the group (A) comprises an azo dichroic dye represented by the general formula [I] and the general formula [II], and the group (B) is It is composed of an azo dichroic dye represented by the general formula [III] and the general formula [IV].

R ¹ , R ² , R ^{5 to} R in the dichroic dyes represented by formulas [I], [II], [III] and [IV] used in the present invention. ⁹ independently represents a hydrogen atom; methyl, ethyl, n-propyl, iso-propyl, n-butyl, t-butyl, pentyl, hexyl, heptyl, octyl or nonyl A C1-C12 alkyl group such as a group; a methoxy group, an ethoxy group, an n-propoxy group,
an alkoxy group having 1 to 12 carbon atoms corresponding to the above alkyl group such as iso-propoxy group, n-butoxy group, t-butoxy group; methoxymethyl group, methoxyethyl group, methoxybutyl group, ethoxymethyl group, ethoxyethyl group or An alkoxyalkyl group having 2 to 12 carbon atoms such as an ethoxybutyl group; a halogen atom such as a fluorine atom, a chlorine atom and a bromine atom; an alkyl having 1 to 12 carbon atoms such as a difluoromethyl group, a trifluoroethyl group and a pentafluoropentyl group A halogen-substituted alkyl group in which a halogen atom such as a fluorine atom is substituted for a group; a halogen-substituted alkoxy group in which a halogen atom such as a fluorine atom is substituted for an alkoxy group having 1 to 12 carbon atoms such as a trifluoroethoxy group or a difluoroethoxy group And preferably a linear alkyl group having 2 to 10 carbon atoms. It is, more preferably 3 to 8 carbon atoms
A linear alkyl group.

R ³ and R ⁴ in the dichroic dye represented by formula [I] each represent a hydrogen atom; a methyl group; a methoxy group; a halogen atom such as a fluorine atom, a chlorine atom, and a bromine atom; Fluoromethyl groups such as fluoromethyl group, difluoromethyl group, and trifluoromethyl group; R ³ and R ⁴ are linked to each other, and together with the phenylene group to which they are bonded, an aliphatic group such as a tetralin ring; A ring or an aromatic ring such as a naphthalene ring may be formed, and preferably a ring in which each is a hydrogen atom or bonded to each other to form a naphthalene ring as a whole. The dichroic dyes represented by the general formulas [I], [II], [III] and [IV]

[0032]

Embedded image As for each, independently

[0033]

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[0034]

Embedded image And preferably,

Embedded image Is mentioned.

The dichroic dye composition of the present invention preferably comprises, as the dichroic dye of the group (A), at least one dye represented by the general formula [I], and (B) Contains one or more from the group of dichroic dyes. More preferably, as the dichroic dye of the group (A), at least one of the dyes represented by the general formula [I], in which R ³ and R ⁴ are linked to each other to form an aromatic ring, is essential. And at least one of the dichroic dyes of group (B).

Particularly preferably, the group (A) comprises the following (A-
When divided into the 1) group and the (A-2) group, the dichroic dye composition of the present invention comprises one or more dichroic dyes represented by the (A-1) group, (A-2) It contains at least one kind from the dichroic dyes represented by the group and at least one kind from the dichroic dyes represented by the group (B).

Group (A-1) Among the azo dichroic dyes represented by the general formula [I], dyes in which R ³ and R ⁴ are linked to form an aromatic ring. (A-2) Group Among the azo dichroic dyes represented by the general formula [I], a dye in which R ³ and R ⁴ are not linked to form an aromatic ring, and a dye represented by the general formula [II] An azo dichroic dye represented.

(A) in the dichroic dye composition of the present invention
The weight ratio of the group and the group (B) varies depending on the hue of the target liquid crystal composition, but is usually 25 to 75:75 to 25, preferably 35 to 65:65 to 35 for dark blue, dark gray, brown, and black. It is. Further, the dichroic dye composition of the present invention may contain other dichroic dyes as long as the effects of the present invention are not impaired. Specific examples of the dichroic dyes of each group used in the present invention include those shown below (Table 1).

[0039]

[Table 1]

[0040]

[Table 2]

[0041]

[Table 3]

[0042]

[Table 4]

The host liquid crystal material used in the present invention includes:
A halogen-based Np-type liquid crystal material containing a liquid crystal compound represented by the following structural formula [V] as a main component, or a halogen containing a liquid crystal compound represented by a structural formula [VI] and a structural formula [VII] as a main component: And a cyano-based Nn-type liquid crystal material, or a cyano-based Np-type liquid-crystal material mainly including a liquid crystal compound represented by the structural formulas [VIII] and [IX].

[0044]

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(In each formula,

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Represents a cyclohexane ring, a benzene ring, a dioxane ring, or a pyrimidine ring, and n represents an integer of 1 to 3. -Z- represents a single bond, -COO -, - CH ₂ CH
_{It represents 2-} , -CH = CH- or -C≡C-.

In the formula [V], Y ¹ and Y ³ each independently represent a hydrogen atom; a halogen atom such as a fluorine group or a chlorine group; Y ² represents a halogen atom such as a fluorine group or a chlorine group; A substituted alkyl group, substituted alkoxy group or substituted alkenyl group having 1 to 7 carbon atoms having a halogen atom such as a group as a substituent; a substituted cyclohexyl group having these substituted alkyl group, substituted alkoxy group or substituted alkenyl group as a substituent or Represents a substituted phenyl group.

Y ⁵ and Y ⁶ in the general formula [VI] each independently represent a cyano group; a halogen atom such as a fluorine group and a chlorine group. Y in the general formulas [VIII] and [IX]
¹¹ , Y ¹³ represents a cyano group. Y ⁴ in general formula [V], Y ⁷ and Y ⁸ in general formula [VI], and general formula [VI
Y ⁹ and Y ¹⁰ in I] and Y ¹² in general formula [VIII]
And Y ¹⁴ in the general formula [IX] each independently represents an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, an alkoxyalkyl group having 2 to 10 carbon atoms, or an alkenyl group having 2 to 10 carbon atoms. Represent. Of these, a fluorine-based liquid crystal in which Y ² in the general formula [V] is a group in which Y ² is substituted with a fluorine atom or fluorine is preferably used in terms of charge retention characteristics in active driving.

The guest-host type liquid crystal composition of the present invention comprises:
Various UV absorbers, antioxidants and chiral nematic liquid crystals with chiral dopants such as cholesteric nanoate and steroidal liquid crystals and chiral nematic liquid crystals with optically active alkyl groups or optically active alkoxy groups introduced into the terminal substituents of the aforementioned liquid crystalline compounds. It may be added usually up to about 0.1 to 10% by weight of the guest-host type liquid crystal composition. Further, other dichroic dyes may be contained as long as the effects of the present invention are not impaired.

The concentration of the dichroic dye in the guest-host type liquid crystal composition of the present invention is usually 0.1 to 15% by weight, preferably 0.5 to 5% by weight, based on the host liquid crystal material. The guest-host type liquid crystal composition of the present invention can be easily obtained by mixing and dissolving the liquid crystal composition, the dichroic dye, and various additives by an operation such as shaking.

The guest-host type liquid crystal composition prepared in this manner can be used in a TN mode or STN mode, and further edited by the 142nd Committee of the Japan Society for the Promotion of Science; “Liquid Crystal Device Handbook”, Nihon Kogyo Shimbun (1989), pp. 315-329. And Heilmeier described in pages 367 to 370 and the like.
At least one of which is processed so as to obtain an electro-optical effect such as various guest host modes such as a type guest host, is sandwiched between transparent electrode substrates, and the Japan Society for the Promotion of Science 142
Committee Edition; "Liquid Crystal Device Handbook", Nihon Kogyo Shimbun (1989), p. 387-434, etc., various display elements by combining various direct drive methods and active drive methods using active elements such as thin film transistors and MIM. Obtainable. The liquid crystal composition of the present invention thus obtained has a high order parameter and a high coloring density, so that a high contrast ratio can be achieved when a liquid crystal display is constructed.

[0052]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist.

Example 1 A dichroic dye having the following structural formula shown in Table 1 was used under the trade name of ZLI-1565 (E. MER).
A liquid crystal composition-I was prepared by mixing and dissolving with 1 g of a liquid crystal mixture containing a cyano-based compound as a main component, which is commercially available as CK Corporation). [I-1] 3.2 mg [I-5] 4.0 mg [III-4] 5.6 mg [III-5] 3.0 mg [IV-1] 1.8 mg

This liquid crystal composition-I was applied to a cell made of a glass plate with a transparent electrode, which was rubbed by applying a polyimide resin, cured and rubbed, and which was arranged so that the alignment-treated surfaces faced each other. A liquid crystal display device was created. After coating and curing the polyimide resin, the liquid crystal composition-I is formed of a glass plate with a transparent electrode that has been rubbed and subjected to a homogeneous alignment treatment, and is injected into a cell in which the alignment treatment surface faces antiparallel, A guest-host type liquid crystal element-I was produced. This element is irradiated with polarized light parallel and perpendicular to the rubbing direction, respectively,
Transmitted light spectra (A parallel and A vertical) were measured.
Using these values, the order parameter was calculated by the following equation. Order parameter (S value) = (A parallel−A vertical) /
(A parallel + 2 × A vertical) Table-2 shows order parameters at each wavelength.

[0055]

[Table 5] Further, the relative absorption spectrum chart of A parallel and A perpendicular is shown in FIG.

[Example 2] Product name ZLI-1565
A liquid crystal composition-II was prepared by mixing and dissolving the following dichroic dye in 1 g of a liquid crystal mixture containing a cyano-based compound as a main component and commercially available as (E. MERCK). [I-3] 3.7 mg [I-5] 1.7 mg [II-1] 1.5 mg [II-2] 0.6 mg [II-3] 0.9 mg [III-1] 4.3 mg [III-2] 3.0 mg [III-5] 2.7 mg [IV-1] 1.8 mg

The liquid crystal composition-II was injected into a cell in the same manner as in Example 1 to prepare a liquid crystal display device-II. The transmitted light spectrum (parallel A and vertical A) of this liquid crystal display device-II was measured in the same manner as in Example 1. The order parameter was calculated using these values. Table 3 shows the order parameters at each wavelength.

[0058]

[Table 6] Further, FIG. 2 shows relative absorption spectrum charts of A parallel and A perpendicular.

[Embodiment 3] Product name ZLI-2806
A liquid crystal composition-III was prepared by mixing and dissolving the following dichroic dye in 1 g of a liquid crystal mixture containing a cyano-based compound as a main component and commercially available (E. MERCK). [I-1] 2.8 mg [I-5] 5.2 mg [II-1] 1.7 mg [III-1] 3.8 mg [III-3] 3.8 mg [III-4] 1.5 mg [III-5] 2.4 mg

This liquid crystal composition-III was injected into a cell in the same manner as in Example 1 to prepare a liquid crystal display element-III. The transmitted light spectrum of this liquid crystal display element-III (A
(Parallel and A vertical) were measured in the same manner as in Example 1. The order parameter was calculated using these values. Table 4 shows order parameters at each wavelength.

[0061]

[Table 7] Further, the relative absorption spectrum chart of A parallel and A perpendicular is shown in FIG.

[Embodiment 4] Product name ZLI-4792
A liquid crystal composition-IV was prepared by mixing and dissolving the following dichroic dye in 1 g of a liquid crystal mixture containing a fluorine-based compound as a main component and commercially available as (E. MERCK). [I-1] 2.8 mg [I-5] 4.1 mg [III-4] 3.5 mg [III-5] 4.5 mg [IV-1] 2.1 mg

This liquid crystal composition-IV was injected into a cell in the same manner as in Example 1 to prepare a liquid crystal display element-IV. The transmitted light spectrum (parallel A and vertical A) of this liquid crystal display device-IV was measured in the same manner as in Example 1. The order parameter was calculated using these values. Table-5 shows the order parameters at each wavelength.

[0064]

[Table 8] Further, the relative absorption spectrum chart of A parallel and A perpendicular is shown in FIG.

[Embodiment 5] Product name ZLI-4792
A liquid crystal composition-V was prepared by mixing and dissolving the following dichroic dye in 1 g of a liquid crystal mixture containing a fluorine-based compound as a main component and commercially available (E. MERCK). [I-1] 1.5 mg [I-5] 1.2 mg [II-1] 1.8 mg [IV-1] 2.3 mg [IV-2] 1.7 mg [IV-5] 1.5 mg

This liquid crystal composition-V was injected into a cell in the same manner as in Example 1 to prepare a liquid crystal display element-V. The transmitted light spectrum (parallel A and vertical A) of this liquid crystal display device-V was measured in the same manner as in Example 1. The order parameter was calculated using these values. Table-6 shows the order parameters at each wavelength.

[0067]

[Table 9] Further, the relative absorption spectrum chart of A parallel and A perpendicular is shown in FIG. 1 to 5, indicates a relative absorption spectrum parallel to A, and indicates a relative absorption spectrum perpendicular to A.

[0068]

As described above, according to the present invention, a guest-host type liquid crystal composition containing an azo dichroic dye having a high dichroism or a high order parameter can be obtained, and excellent contrast characteristics and light stability can be obtained. This has the effect of realizing a guest-host type liquid crystal element having the same.

[Brief description of the drawings]

FIG. 1 shows a relative absorption spectrum chart of A parallel and A vertical in Example 1.

2 shows a relative absorption spectrum chart of A parallel and A perpendicular in Example 2. FIG.

FIG. 3 is a relative absorption spectrum chart of A parallel and A vertical in Example 3.

4 shows a relative absorption spectrum chart of A parallel and A perpendicular in Example 4. FIG.

5 shows a relative absorption spectrum chart of A parallel and A vertical in Example 5. FIG.

FIG. 6 is a schematic cross-sectional view of a reflection type liquid crystal display device in a phase transition mode as an example of a liquid crystal display device according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Incident light 2 Glass substrate 3 Transparent electrode 4 Alignment film 5 Dichroic dye 6 Liquid crystal composition 7 Reflective layer 8 Reflected light

Claims (4)

[Claims] 1. A dichroic dye composition comprising the following (A)
A dichroic dye composition comprising at least one of the dichroic dyes represented by the group and the group (B) from each group. (A) Group Azo dichroic dyes represented by the following general formulas [I] and [II] (Wherein, Are each independently: Or Wherein R ¹ and R ² each independently represent a hydrogen atom, an alkyl group having 1 to 12 carbon atoms which may be substituted with a halogen atom, or a carbon atom which may be substituted with a halogen atom.
Represents an alkoxyalkyl group having 2 to 12 carbon atoms, an alkoxyalkyl group having 2 to 12 carbon atoms which may be substituted with a halogen atom, or a halogen atom, and R ³ and R ⁴ each independently represent a hydrogen atom, a methyl group, a methoxy group, a halogen atom. Represents an atom or a fluoromethyl group, and R ³ and R ⁴ may be linked to each other to form an aliphatic ring or an aromatic ring. ) (In the formula, R ⁵ and R ⁶ are each independently a hydrogen atom, an alkyl group having 1 to 12 carbon atoms which may be substituted with a halogen atom, or a C 1 to 12 carbon atom which may be substituted with a halogen atom. Represents an alkoxy group, an alkoxyalkyl group having 2 to 12 carbon atoms which may be substituted by a halogen atom or a halogen atom.) (B) Group represented by the following general formula [III] and the following general formula [IV] Azo dichroic dye (Wherein, Are each independently: Or Wherein R ⁷ and R ⁸ are each independently a hydrogen atom, an alkyl group having 1 to 12 carbon atoms which may be substituted by a halogen atom, or 1 carbon atom which may be substituted by a halogen atom.
Represents an alkoxy group having 1 to 12 carbon atoms, an alkoxyalkyl group having 2 to 12 carbon atoms which may be substituted with a halogen atom, or a halogen atom. ) (Wherein: Is Or The stands, R ⁹ is a hydrogen atom, an alkyl group having 1 to 12 carbon atoms which may be substituted with a halogen atom, an alkoxy group having 1 to 12 carbon atoms which may be substituted with a halogen atom,
Represents an alkoxyalkyl group having 2 to 12 carbon atoms which may be substituted with a halogen atom or a halogen atom. ) 2. A guest-host type liquid crystal composition comprising the dichroic dye composition according to claim 1 and a host liquid crystal. 3. The liquid crystal composition according to claim 2, wherein a fluorine-based liquid crystal material is used as the host liquid crystal. 4. A liquid crystal display device wherein at least one of the guest-host liquid crystal compositions according to claim 2 or 3 is sandwiched between transparent electrode-attached substrates.