JPH09291282A - Stabilized liquid crystal material and liquid crystal element using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize a liquid crystal compound useful for display elements such as twist nematic type liquid crystal elements, excellent in refractive index anisotropy and suitable for liquid crystal materials or its composition by mixing a specific liquid crystal compound or a composition containing the compound with an antioxidant or a light stabilizer. SOLUTION: This liquid crystal material is obtained by mixing (A) a compound of formula I [M and N are each 1,4-cyclohexylene, 1,4-cyclohexenylene, etc.; Z<1> and Z<2> are each a single bond, O, etc.; X<1> to X<4> are each CH, CF or N; W is a single bond, CH2 CH2 , etc.; L is a group of formula II, a group of formula III, etc.; R is H, F, CF3 , etc.; R' is an (optically active asymmetric carbon-containing) 1-12C alkyl, 1-12C alkoxy, 2-12C alkenyl or 2-12C alkoxyalkyl and when W is a single bond, R' is F, CF3 , CN, etc.; (a), (b), (c) and (d) are each 0 or 1] or a composition containing the compound with (B) an antioxidant (B1 ) or a light stabilizer (B2 ). Furthermore, the liquid crystal material contains preferably 0.001-5wt.% component B.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a TN (twisted nematic) type liquid crystal element, an STN (super twisted nematic) type liquid crystal element, an FLCD (ferroelectric liquid crystal display), and a P type.
A method for stabilizing a liquid crystal material used in a display element represented by a DLC (polymer dispersed liquid crystal) type liquid crystal element, and a liquid crystal material stabilized by using the stabilizing method and these liquid crystal materials are used. Liquid crystal device.

[0002]

2. Description of the Related Art In recent years, with the progress of information-oriented society, various display elements are becoming more important as one of man-machine interfaces. Under these circumstances, flat displays, especially liquid crystal displays (LCDs)
Has been rapidly spreading due to its features such as thinness, light weight, low voltage drive, and low power consumption. As its name implies, a liquid crystal display utilizes a liquid crystal composition in its display portion, and it can be said that the liquid crystal composition is, so to speak, a component forming the core of the liquid crystal display. The liquid crystal composition is composed of an organic compound. The fact that it is incorporated into precision electrical products requires the liquid crystal composition to: The liquid crystal composition has stability such that it can withstand the harsh conditions of the manufacturing process of the liquid crystal display, and in order for the manufactured liquid crystal display to stably exhibit its excellent performance over a long period of time, the liquid crystal composition is It is also necessary for a product to have long-term stability in which the physical properties do not change during its use period. That is, the liquid crystal composition must withstand heat of 100 ° C. or higher in the manufacturing process of a liquid crystal display for several hours, and must be stable over a period of use ranging from several thousand hours to several tens of thousands of hours. This condition is extremely severe for a liquid crystal composition that is an organic compound, and even if it has excellent properties, it cannot satisfy this stability condition, and therefore a liquid crystal compound that can be actually used in a liquid crystal display. Are limited. On the other hand, with the advent of the information society, high performance of liquid crystal display elements is indispensable. For example, in order to increase the speed of liquid crystal display elements, a liquid crystal material having excellent refractive index anisotropy is required. For example, in Japanese Patent Laid-Open No. 7-53417,

[0003]

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Various liquid crystal compounds have been found, such as.

[0005]

However, no effective method has been found so far for stabilizing various liquid crystal compounds or mixtures thereof accompanying the improvement in performance of liquid crystal display devices.

[0006]

Means for Solving the Problems The inventors of the present invention have made earnest studies on a method of stabilizing a liquid crystal compound or a mixture thereof suitable for a liquid crystal material having excellent refractive index anisotropy, and as a result, an antioxidant and / or They found that the light stabilizer is effective, and completed the present invention. That is, the following general formula (1)

[0007]

[Chemical 6]

[Wherein M and N are each independently

[0009]

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Wherein Z ¹ and Z ² are each independently a single bond, --O--, --CH ₂ CH _2- , --COO-- or --O.
Represents CO-, X ¹ , X ² , X ³ , X ⁴ , Y ¹ , Y ² ,
Y ³ and Y ⁴ each independently represent CH, CF or N,
W is a single _{bond, -CH 2 CH 2 -, -} CF 2 CF 2 -, -
_{CF 2 CH 2 -, - CH} 2 CF 2 -

[0011]

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Represents L, and L is

[0013]

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Represents a, b, c or d represents 0 or 1, and R represents a hydrogen atom, a fluorine atom, a trifluoromethyl group, a difluoromethyl group, a monofluoromethyl group, a trifluoromethoxy group, a difluoromethoxy group. Group, monofluoromethoxy group, cyano group, C ₁ -C ₁₂ alkyl group, C
₁ -C ₁₂ alkoxy group, C ₂ -C ₁₂ alkenyl or C
Represents ₂ -C ₁₂ alkoxyalkyl an alkyl group, R 'is an optionally C ₁ -C ₁₂ alkyl group optionally contain asymmetric carbon exhibit optical activity, C ₁ -C ₁₂ alkoxy group, C ₂ -C ₁₂ alkenyl group, or It represents a C ₂ -C ₁₂ alkoxyalkyl group. Also, W
Is a single bond, R ′ is a fluorine atom, a trifluoromethyl group, a difluoromethyl group, a monofluoromethyl group, a trifluoromethoxy group, a difluoromethoxy group,
It may be a monofluoromethoxy group or a cyano group. ] The compound shown by these, or the composition containing at least 1 sort (s) thereof, and at least 1 sort (s) of antioxidant and / or at least 1 sort (s) of light stabilizer, and the stabilization method of the liquid crystal material characterized by the above-mentioned. Liquid crystal material, stabilized using
Also provided is a liquid crystal element in which the liquid crystal material is sandwiched between a pair of electrode plates. Hereinafter, the present invention will be described in detail.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The content of the antioxidant and / or the light stabilizer in the liquid crystal material in the present invention is 0.001 to 5
% By weight.

In the present invention, examples of the antioxidant include phenol type antioxidants, phosphite type antioxidants, phosphoite type antioxidants, sulfur type antioxidants, and the like, and examples of the light stabilizer include hindered amine type light stabilizers. Examples thereof include stabilizers, benzophenone-based light stabilizers, triazole-based light stabilizers, and nickel-based quenchers.

In the present invention, the phenolic antioxidant is not particularly limited, but compounds having the following structure as a partial structure are exemplified. Equation 1

[0018]

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[In the formula, R ¹ and R ² each independently represent a hydrogen atom or an alkyl group. ] As a preferred specific example, 2,6-di-t-butyl-4
-Methylphenol, octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, 2,2'-methylenebis (6-t-butyl-4-methylphenol), 2-t-butyl -6- (3-t-Butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate, 2- [1- (2-hydroxy-3,5-di-t-pentylphenyl) ethyl]-
4,6-di-t-pentylphenyl acrylate, 4,
4'-butylidene bis (6-t-butyl-3-methylphenol), 3,9'-bis [2- {3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionyloxy} -1 , 1-Dimethylethyl] -2,4
8,10-tetraoxaspiro [5.5] undecane,
2- (3,5-di-t-butyl-4-hydroxyanilino) -4,6-bis (n-octylthio) -1,3,5
-Triazine, 2,2'-ethylidene bis (4,6-di-t-butylphenol), 2,2'-ethylidene bis (4-sec-butyl-6-t-butylphenol),

2,2'-thiobis (6-t-butyl-3)
-Methylphenol), 1,1,3-Tris (5-t-
Butyl-4-hydroxy-2-methylphenyl) butane, bis [2-t-butyl-4-methyl-6- (3-t
-Butyl-2-hydroxy-5-methylbenzyl) phenyl] terephthalate, tetrakis [methylene-3-]
(3,5-di-t-butyl-4-hydroxyphenyl)
Propionate] methane, 2,2'-thiodiethylenebis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], triethyleneglycolbis [3- (3-t-butyl-4- Hydroxy-5-methylphenyl) propionate], 1,6-hexanediolbis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], 1,3,5-tris (3,5) -Di-t-butyl-4-hydroxybenzyl)
Isocyanurate, 1,3,5-Tris [2- {3-
(3,5-di-t-butyl-4-hydroxyphenyl)
Propionyloxy} ethyl] isocyanurate, 1,
3,5-Tris (4-t-butyl-3-hydroxy-
2,6-dimethylbenzyl) isocyanurate, 1,
Examples thereof include 3,5-tris (3,5-di-t-butyl-4-hydroxybenzyl) -2,4,6-trimethylbenzene.

In the present invention, the sulfur-based antioxidant is not particularly limited, but compounds represented by the following formulas 2 and 3 are exemplified. Equation 2

S- (CH ₂ CH ₂ —COOR ³ ) ₂ (Formula 2) [In the formula, R ³ is an alkyl group, preferably C _{12 to} C ₁₈
Represents an alkyl group. ] Formula 3

[0023]

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[In the formula, R ⁴ represents an alkyl group, preferably a C ₁₂ alkyl group. Specific preferred examples include dilauryl 3,3′-thiodipropionate, dimyristyl 3,3′-thiodipropionate, distearyl 3,3′-thiodipropionate, tetrakis (3-laurylthiopropionyloxymethyl) ) Methane and the like. Furthermore, in the present invention, the phosphite-based antioxidant and the phosphite-based antioxidant are not particularly limited, but compounds represented by the following formulas 4 to 9 are exemplified. Equation 4 P- (OR ⁵⁾ ₃ (Formula 4) wherein, R ⁵ represents an optionally substituted alkyl group or an aryl group. ] Equation 5 and Equation 6

[0025]

[Chemical 12]

[In the formula, R ⁶ represents an optionally substituted alkyl group or aryl group, and R ⁷ , R ⁸ and R ⁹ are
Each independently represents a hydrogen atom or a C ₁ -C ₈ alkyl group, R ¹⁰ represents a fluorine atom or an alkyl group, and X represents a single bond, an oxygen atom or a nitrogen atom. ]

[0027]

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[In the formula, R ¹¹ and R ¹² each independently represent a hydrogen atom or an alkyl group, and R ¹³ represents a hydrogen atom or an alkyl group. However, when R ¹³ is a hydrogen atom,

[0029]

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There is a resonance structure of phosphinate compound. ] As a preferable specific example, tris (nonylphenyl)
Phosphite, tris (2,4-di-t-butylphenyl) phosphite, tetrakis (2,4-di-t-butylphenyl) 4,4'-biphenylene diphosphonate, bis (2,4-di) -T-butylphenyl) pentaerythritol diphosphite, bis (2,6-di-t-butylphenyl) pentaerythritol diphosphite distearyl pentaerythritol diphosphite, phenyl diisooctyl phosphite, phenyl diisodecyl phosphite, phenyl di (tridecyl) phosphite, Diphenyl isooctyl
Phosphite, diphenyl isodecyl phosphite, diphenyl tridecyl phosphite, 4,4 '
-Isopropylidene bis (phenyldialkyl phosphite), 2,2'-methylenebis (4,6-di-t-
Butylphenyl) octyl phosphite, 2,2'-
Examples thereof include ethylidene bis (4,6-di-t-butylphenyl) fluorophosphonite. In the present invention, the hindered amine light stabilizer is not particularly limited, but examples thereof include compounds having the following structure as a partial structure. Equation 10

[0031]

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As a preferred specific example, bis (2,2,2
6,6-Tetramethyl-4-piperidyl) sebacate, bis (N-methyl-2,2,6,6-tetramethyl-4-piperidyl) sebacate, N, N ′ bis (2,2
2,6,6-tetramethyl-4-piperidyl) -1,6
-Hexamethylenediamine, 2-methyl-2- (2,
2,6,6-Tetramethyl-4-piperidyl) amino-
N- (2,2,6,6-tetramethyl-4-piperidyl) propionamide, tetrakis (2,2,6,6-
Tetramethyl-4-piperidyl) (1,2,3,4-
Butane tetracarboxylate, poly [{6- (1,
(1,3,3-tetramethylbutyl) imino-1,3,5
-Triazine-2,4-diyl} (2,2,6,6-
Tetramethyl-4-piperidyl) imino} hexamethyl {(2,2,6,6-tetramethyl-4-piperidyl)
Imino}], poly [(6-morpholino-1,3,5-triazine-2,4-diyl) {(2,2,6,6-tetramethyl-4-piperidyl) imino} hexamethine {(2,2 , 6,6-Tetramethyl-4-piperidyl)
Imino}], a polycondensation product of dimethyl succinate and 1- (2-hydroxyethyl) -4-hydroxy-2,2,6,6-tetramethylpiperidine, N, N′4,7-tetrakis [4. 6-bis {N-butyl-N- (1,2,
2,6,6-Pentamethyl-4-piperidyl) amino}
-1,3,5-triazin-2-yl] -4,7-diazadecane-1,10-diamine and the like can be mentioned. In the present invention, the benzophenone-based light stabilizer is not particularly limited, but examples thereof include compounds having the following structure as a partial structure. Equation 11

[0033]

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Specific examples include 2,4-dihydroxybenzophenone and 2-hydroxy-4-methoxybenzophenone.

In the present invention, the triazole-based light stabilizer is not particularly limited, but compounds having the following structure as a partial structure are exemplified. Equation 12

[0036]

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As a specific example, 2- (2-hydroxy-)
5-methoxyphenyl) benzotriazole, 2- (2
-Hydroxy-3,5-t-butylphenyl) benzotriazole and the like. In the present invention, the nickel-based quenching agent is not particularly limited, but an organic nickel-based one is mentioned as a basic skeleton, and specific examples thereof include nickel dibutyldithiocarbamate and the like.

Examples of the liquid crystal material include an alkyl group which may be fluorine-substituted, an alkenyl group which may be fluorine-substituted, an alkynyl group which may be fluorine-substituted, an alkoxy group which may be fluorine-substituted, Fluorine-substituted alkoxyalkyl group, fluorine atom or cyano group as a substituent, biphenyl-based, phenylcyclohexane-based, tran-based, stilbene-based or terphenyl-based compounds, or a mixture thereof, etc. Is mentioned. Furthermore, the following compounds can be illustrated.

[0039]

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R is a hydrogen atom, a fluorine atom, a trifluoromethyl group, a difluoromethyl group, a monofluoromethyl group, a trifluoromethoxy group, a difluoromethoxy group,
Represents a monofluoromethoxy group, a cyano group, a C ₁ -C ₁₂ alkyl group, a C ₁ -C ₁₂ alkoxy group, a C ₂ -C ₁₂ alkenyl group or a C ₂ -C ₁₂ alkoxyalkyl group, and R ′ represents C ₁ -C. ₁₂ alkyl group, C ₁ -C ₁₂ alkoxy group, C ₂
To C ₁₂ alkenyl group or C _{2 to} C ₁₂ alkoxyalkyl group, and when W is a single bond, fluorine atom, trifluoromethyl group, difluoromethyl group, monofluoromethyl group, trifluoromethoxy group, difluoromethoxy group It may be a monofluoromethoxy group or a cyano group. Further, the aromatic ring of the above compound may be substituted with a fluorine atom. ]

[0041]

The present invention provides a TN (twisted nematic) type liquid crystal element, an STN (super twisted nematic) type liquid crystal element,
It is useful as a method for stabilizing a liquid crystal composition used in a display device represented by FLCD (ferroelectric liquid crystal display) and PDLC (polymer dispersed liquid crystal) liquid crystal device. Further, it is possible to provide a stabilized liquid crystal composition using the stabilization method and a liquid crystal device using the liquid crystal composition.

[0042]

EXAMPLES Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In Examples 1 to 2, a liquid crystal compound and an antioxidant were added.
Weight% addition, heat resistance test (150 ℃, 2
Time, and then liquid chromatography (column S)
UMIPAX QSDA-212 6mmπX15c
The purity of the compound was quantified using m, 254 nm, MeC Resolution).

Example 1 To 50 mg of 4- (4-pentylcyclohexyl) benznitrile (5PCH) was added tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl), a phenolic antioxidant. ) Propionate] 2% by weight of methane was added, and heat resistance test (150
(° C, 2 hours), and the recovery rate was determined by liquid chromatography. For comparison, the same test was conducted without adding the antioxidant. Table 1 shows the results.

[0044]

[Table 1]

Example 2 50 mg of 4-pentyl-cyanobiphenyl (5CB)
2% by weight of tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane, which is a phenolic antioxidant, was added to, and a heat resistance test in the dark in the air ( It was measured at 150 ° C. for 2 hours and by liquid chromatography. For comparison, the same test was conducted without adding the antioxidant. The results are shown in Table 2.
Shown in

[0046]

[Table 2]

Examples 3 to 6 To 50 mg of 4- (4-propylcyclohexyl) benznitrile (3PCH), 2% by weight of an antioxidant was added, and a heat resistance test (150 ° C., 2 hours) was conducted in the dark in the air. Performed and determined by liquid chromatography. For comparison, the same test was conducted without adding the antioxidant. Table 3 shows the results. Liquid chromatograms of Example 5 and Comparative Example are shown in FIGS. 1 and 2.

[0048]

[Table 3]

Antioxidant A: Dimyristyl 3,3'-thiodipropionate B: Tris (nonylphenyl) phosphite (phosphoric acid antioxidant) 2% by weight C / D: 2,6-di-t- Butyl-4-methylphenol (phenolic antioxidant 1% by weight / tris (2,4
-Di-t-butylphenyl) Phosphite (phosphoric acid type antioxidant) 1% by weight C / B: 2,6-di-t-butyl-4-methylphenol (phenolic type antioxidant 1% by weight / Tris (Nonylphenyl) phosphite (phosphoric acid antioxidant) 1% by weight

Example 7 4-Pentyl-cyanobiphenyl (5CB) (300 m
To g), 0.2% by weight of hindered amine benzoate bis (N-methyl-2,2,6,6-tetramethyl-4-piperidine) sebacate was added. Put this in a sample tube and make it a Shimadzu light resistance tester Suntester XF-18
It was irradiated with light at 0 for 16 hours, and the recovery rate was determined by liquid chromatography. As a comparison, the same test was conducted without adding the light stabilizer. The results are shown in Table 4.

[0051]

[Table 4]

[Brief description of drawings]

FIG. 1 shows a liquid chromatogram obtained in Example 5.

FIG. 2 shows liquid chromatograms of comparative examples of Examples 3 to 6.

Continuation of front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical indication location C09K 19/34 C09K 19/34 G02F 1/13 500 G02F 1/13 500 (72) Inventor Maeda Yasuteru Tsukuba, Ibaraki Prefecture Ichi Kitahara 6 Sumitomo Chemical Co., Ltd. (72) Inventor Koichi Fujisawa 6 Tsukuba City, Ibaraki Prefecture Kitahara 6 Sumitomo Chemical Co., Ltd. (72) Inventor Tetsuo Yamaguchi 6 Ibaraki Tsukuba City Kitahara 6 Sumitomo Chemical Co., Ltd.

Claims (6)

[Claims] 1. The following general formula (1): [Wherein, M and N are each independently And Z ¹ and Z ² are each independently a single bond or —O.
_{-, - CH 2 CH 2 -} , represents -COO- or ^{-OCO-, X 1, X 2,} X 3,
X ⁴ , Y ¹ , Y ² , Y ³ and Y ⁴ are each independently C
Represents H, CF or N, W is a single bond, —CH ₂ CH
_{2 -, - CF 2 CF 2} -, - CF 2 CH 2 -, - CH 2
CF ₂ - ## STR3 ## And L is Represents a, b, c or d represents 0 or 1, R represents a hydrogen atom, a fluorine atom, a trifluoromethyl group, a difluoromethyl group, a monofluoromethyl group, a trifluoromethoxy group, a difluoromethoxy group, a monofluoromethyl group. Fluoromethoxy group, cyano group, C ₁ ~
C ₁₂ alkyl group, C ₁ -C ₁₂ alkoxy group, C ₂ -C ₁₂
Represents an alkenyl group or a C ₂ -C ₁₂ alkoxyalkyl group, and R ′ represents a C ₁ -C ₁₂ alkyl group which may contain an asymmetric carbon showing optical activity, a C ₁ -C ₁₂ alkoxy group, C ₂
To C ₁₂ alkenyl group or C _{2 to} C ₁₂ alkoxyalkyl group. When W is a single bond, R ′ is a fluorine atom, a trifluoromethyl group, a difluoromethyl group,
It may be a monofluoromethyl group, a trifluoromethoxy group, a difluoromethoxy group, a monofluoromethoxy group or a cyano group. ] The compound shown by these or the composition containing at least 1 sort (s) thereof, and at least 1 sort (s) of antioxidant and / or at least 1 sort (s) of light stabilizer are mixed, The stabilizing method of the liquid crystal material characterized by the above-mentioned. 2. The method according to claim 1, wherein the content of the antioxidant and / or the light stabilizer is 0.001 to 5% by weight. 3. The method according to claim 1, wherein the antioxidant is a phenol-based antioxidant, a phosphite-based antioxidant, a phosphite-based antioxidant or a sulfur-based antioxidant. 4. The method according to claim 1, wherein the light stabilizer is a hindered amine light stabilizer, a benzophenone light stabilizer, a triazole light stabilizer or a nickel quencher. 5. A liquid crystal material stabilized by the method according to claim 1. 6. A liquid crystal device comprising the liquid crystal material according to claim 5 sandwiched between a pair of electrode plates.