JP5646827B2 - Liquid crystal medium and liquid crystal display having high twist - Google Patents

Description

  The present invention relates to a liquid crystal medium having a high twist, its use for electro-optical purposes, and a display containing this medium.

  Liquid crystal displays are known from the prior art. The most common display devices are based on the Schadt-Helfrich effect, and liquid crystal media having a twisted nematic structure, such as TN ("twisted nematic") cells, typically having a twist angle of 90 °, and typically In particular, STN (“super-twisted nematic”) cells having a twist angle of 180 to 270 ° are included. Ferroelectric liquid crystal displays containing a liquid crystal medium having a twisted smectic structure are also known. The twisted structure in these displays is usually achieved by adding one or more chiral dopants to a nematic or smectic liquid crystal medium.

  Liquid crystal displays containing liquid crystal (LC) media having a chiral nematic or cholesteric structure are also known. These media have a significantly higher twist compared to media from TN and STN cells.

  The cholesteric liquid crystal exhibits selective reflection with respect to circularly polarized light in which the rotation direction of the light vector corresponds to the rotation direction of the cholesteric helical. The reflection wavelength λ is given according to equation (1) by the pitch p of the cholesteric helical and the average birefringence n of the cholesteric liquid crystal.

用語「キラルネマチック」および「コレステリック」は、先行技術において、互いに並列して用いられている。「キラルネマチック」は、しばしば、ヘリカルツイスト超構造を誘発する光学活性成分でドープされたネマチックホスト混合物からなるＬＣ材料を表す。一方、「コレステリック」は、しばしば、ヘリカルツイストを有する「天然の」コレステリック相を有するキラルＬＣ材料、例えばコレステリル誘導体を表す。また、２つの用語は、同一のものを表すために並行しても用いられる。本出願においては、用語「コレステリック」をＬＣ材料の両方の上記のタイプについて用い、この用語は、「キラルネマチック」および「コレステリック」の各々の場合における最も広い意味を網羅するものとする。

The terms “chiral nematic” and “cholesteric” are used in parallel with each other in the prior art. “Chiral nematic” often refers to an LC material consisting of a nematic host mixture doped with an optically active component that induces a helical twist superstructure. On the other hand, “cholesteric” often refers to chiral LC materials having a “natural” cholesteric phase with a helical twist, eg cholesteryl derivatives. Two terms are also used in parallel to represent the same thing. In this application, the term “cholesteric” is used for both the above types of LC materials, and this term shall cover the broadest meaning in each case of “chiral nematic” and “cholesteric”.

  Examples of conventional cholesteric liquid crystal (CLC) displays are the so-called SSCT ("surface stabilized cholesteric texture") and PSCT ("polymer stabilized cholesteric textured") displays. SSCT and PSCT displays usually contain a CLC medium, which has a planar structure that reflects light having a specific wavelength, for example, in the initial state, and a focal conic by applying an alternating voltage pulse. can switch to a conical light scattering structure, or vice versa. When a stronger voltage pulse is applied, the CLC medium is converted to a homeotropic transparent state from which the CLC medium relaxes to a planar state after a rapid voltage switch-off or after a slow switch-off. Relaxes to the focal conic state.

  In the SSCT display, the planar orientation of the CLC medium in the initial state, i.e. before application of voltage, is achieved, for example, by surface treatment of the cell walls. In PSCT displays, the CLC media further comprises phase separated polymers or polymer networks that stabilize the structure of the CLC media in the addressed state.

  SSCT and PSCT displays generally do not require a backlight. In the planar state, the CLC medium in the pixel exhibits selective light reflection of a specific wavelength according to equation (1) above, which means that the pixel exhibits a corresponding reflection color, for example, in front of a black background. To do. The reflected color disappears when it changes to a focal conic, scattering or homeotropic transparency.

  SSCT and PSCT displays are bistable, that is, their respective states are maintained after the electric field is switched off and only return to the initial state by applying a new electric field. Thus, a short voltage pulse is sufficient to form a pixel, which is in contrast to, for example, electro-optic TN or STN displays, in which the LC media in the addressed pixel has an electric field. As soon as it is switched off, it returns to its initial state, which means that the permanent formation of the pixel requires maintaining the address voltage.

  For the above reasons, CLC displays have significantly lower power consumption compared to TN or STN displays. In addition, CLC displays show little or no viewing angle dependence in the scattering state. In addition, the CLC display does not require an active matrix address as in the case of a TN display, and can instead operate in a simpler multiplex or passive matrix mode.

  WO 92/19695 (Patent Document 1) and US Pat. No. 5,384,067 (Patent Document 2) include, for example, a CLC medium having positive dielectric anisotropy, and 10% by weight. A PSCT display containing a polymer network dispersed and phase separated in a liquid crystal material up to is described. U.S. Pat. No. 5,453,863 (Patent Document 3) describes, for example, an SSCT display containing a CLC medium having positive dielectric anisotropy and no polymer.

  The CLC medium for the above display can be produced, for example, by doping a nematic LC mixture with a chiral dopant having a high twisting power. The induced cholesteric helical pitch p is given according to equation (2) by the concentration c and the helical twisting power of the chiral dopant HTP (helical twisting power).

また、例えばそれぞれのドーパントのＨＴＰの温度依存性を補償し、よってＣＬＣ媒体のヘリカルピッチおよび反射波長の低い温度依存性を達成するために、２種類以上のドーパントを用いることも可能である。

It is also possible to use two or more dopants, for example to compensate for the temperature dependence of the HTP of each dopant, thus achieving a low temperature dependence of the helical pitch and reflection wavelength of the CLC medium.

  In order to be used in the above displays, the chiral dopant must have the highest possible helical twist force and low temperature dependence, high stability in the liquid crystal host phase and good solubility. In addition, the adverse effects of chiral dopants on the liquid crystal and electro-optical properties of the liquid crystal host phase must be as low as possible. A high helical twisting force of the dopant is particularly desirable in order to achieve a small pitch, for example in cholesteric displays, but also to be able to reduce the dopant concentration. This first achieves a reduction in the potential for liquid crystal properties to be impaired by the dopant, and secondly increases the tolerance for the solubility of the dopant, for example using a dopant having a relatively low solubility. It becomes possible.

  In general, CLC materials for use in the above displays must have good chemical and thermal stability and good stability to electric fields and electromagnetic radiation. Furthermore, the liquid crystal material must have a broad cholesteric liquid crystal phase with a high clearing point, a sufficiently high birefringence, a high positive dielectric anisotropy and a low rotational viscosity.

  In addition, the CLC material must have the property that various reflection wavelengths can be achieved with simple and targeted variations, especially in the visible region. In addition, the CLC material must have a low temperature dependence of the reflection wavelength.

  In general, since liquid crystals are used in the form of a mixture of a plurality of components, it is important that the components are easily miscible with each other. Additional properties such as dielectric anisotropy and optical anisotropy must meet various requirements depending on the cell type.

  However, it is impossible to achieve favorable values for all of the above parameters using media available from the prior art.

  EP 0 450 025 (Patent Document 4) describes, for example, a cholesteric liquid crystal mixture comprising a nematic liquid crystal containing two or more kinds of chiral dopants. However, the mixture shown here has only a low clearing point. In addition, the mixture contains as high as 26% chiral dopant. However, the high dopant concentration generally results in the loss of the electro-optical properties of the liquid crystal and CLC media.

  Materials known from the prior art for CLC displays often do not have a sufficiently broad LC phase, a sufficiently low viscosity value and a sufficiently high value of dielectric anisotropy. In addition, they require high switch voltages and often do not have birefringence values that match the required LC layer thickness.

  Thus, for example, for many CLC displays, CLC media with high birefringence Δn are required to achieve high reflectivity, while other CLC displays, such as displays where high saturation is a priority (multiple Color CLC displays) require low values of Δn. However, it has been found that using the CLC media known from the prior art cannot reduce the birefringence to an appropriate degree while maintaining the high polarity of the CLC media required for low switch voltages. It was issued.

  Thus, it does not have the disadvantages of the media known from the prior art, or only to a lesser extent, high twist, large operating temperature range, short response time, low threshold voltage, low temperature dependence of the reflection wavelength and especially There is a great demand for CLC media with low values of refraction.

  For use in CLC displays, especially SSCT displays, CLC media must additionally have good dielectric behavior, a wide operating temperature range and good saturation.

International Publication No. 92/19695 Pamphlet US Pat. No. 5,384,067 US Pat. No. 5,453,863 EP 0 450 025 specification

  The present invention has the above required characteristics and does not have the disadvantages of media known from the prior art or has only to a lesser extent, in particular CLC displays such as SSCT and PSCT displays, and other bistables The object is to provide a CLC medium for use in a CLC display.

  It has been found that this object can be achieved when the medium according to the invention is used in this type of display.

The present invention is a liquid crystal medium having a helical twist structure and including a nematic component and an optically active component,
The optically active component includes one or more chiral compounds whose helical twist force and concentration are selected such that the helical pitch of the medium is 1 μm or less,
The nematic component has the formula I:

の１種類以上の化合物と、
式ＩＩ：

One or more compounds of
Formula II:

の１種類以上の化合物と、
式ＩＩＩ：

One or more compounds of
Formula III:

の１種類以上の化合物と
を含むことを特徴とする液晶媒体に関する。

And a liquid crystal medium characterized by comprising one or more compounds.

Where
R ¹ and R ² are each independently of one another H or an alkyl or alkenyl group having 1 to 20 carbon atoms, which group is unsubstituted or monosubstituted by CN or CF ₃ , Or at least monosubstituted by halogen, and one or more CH ₂ groups in these groups are each independently of each other —O—, —S—, so that the O atoms are not directly bonded to each other. May be substituted by —CO—, —CO—O—, —O—CO—, —O—CO—O—, —CH═CH— or —C≡C—,

Ｚ^１は、−ＣＯＯ−、−ＣＨ_２ＣＨ_２−または単結合であり、
Ｚ^２は、−ＣＯＯ−、−ＣＨ_２ＣＨ_２−または単結合であり、
Ｌ^１〜５は、それぞれ互いに独立に、ＨまたはＦであり、
ａおよびｂは、それぞれ互いに独立に、０または１である。

Z ¹ is —COO—, —CH ₂ CH ₂ — or a single bond,
Z ² is —COO—, —CH ₂ CH ₂ — or a single bond,
L ^1-5 are each independently H or F,
a and b are each independently 0 or 1;

  The invention further relates to the use of the CLC media according to the invention for electro-optical purposes, in particular in CLC displays such as bistable CLC displays, SSCT and PSCT displays.

  Furthermore, the present invention comprises two planar parallel skins that form a cell with a frame and a CLC medium disposed in the cell, the CLC medium being a medium as described above and below. It relates to certain electro-optic displays, in particular bistable CLC, SSCT or PSCT displays.

  Surprisingly, according to the invention, it has a cholesteric phase at the reflection wavelength in the visible region and / or at room temperature, a moderate to low birefringence value, but a dielectric anisotropy to achieve a low response time It has been found that CLC media with sufficiently high values of the property Δε can be provided. In the CLC medium according to the invention, this is achieved in particular by using compounds of the formulas I, II and III together with highly twisted chiral dopants as described below.

  Thus, when compounds of formulas I, II and III are used in mixtures for CLC displays according to the present invention, high polarity, i.e. low threshold voltage, and high Δn value are obtained, high transparency in the switched state, Short response times and a wide operating temperature range are achieved.

  In addition, the CLC media according to the present invention, when used in a CLC display, exhibit excellent properties with respect to saturation and UV stability when combined with compounds of formulas I, II and III. In particular, this makes it possible to achieve CLC and SSCT displays that are not orange and can display red due to the highly yellow and green components of SSCT displays known to date.

  The compounds of Formulas I and II are particularly useful for achieving CLC media with very high positive dielectric anisotropy Δε and reducing the threshold voltage of the display.

  The compounds of formula III are particularly useful for increasing the birefringence of CLC media and display contrast.

  Furthermore, achieving the high polarity required for an acceptable switch voltage is surprisingly not adversely affected here.

Furthermore, the mixtures according to the invention are distinguished by the following advantages:
The mixture has a wide cholesteric phase range and a high clearing point, especially at low temperatures;
The mixture has a high UV stability;

  The compounds of formulas I, II and III have a wide range of uses. Depending on the choice of substituents, these compounds can function as the base material from which the liquid crystal medium is primarily composed, but also change, for example, the dielectric and / or optical anisotropy of this type of dielectric. It is also possible to add compounds of the formulas I, II and III to liquid crystal base materials from other classes of compounds in order to optimize the threshold voltage of the dielectric and / or the viscosity of the dielectric is there. In the pure state, the compounds of the formulas I, II and III are colorless and form liquid-crystalline mesophases in the preferred temperature range for electro-optical use. The compounds of formulas I, II and III are chemically, thermally and light stable.

Particular preference is given to compounds of the formula I in which at least ^{one of the} radicals A ¹ and A ² is trans-1,4-cyclohexylene and / or Z ¹ is —COO—.

  The compound of formula I is preferably selected from the following formulae:

式中、Ｒ^１は式Ｉ中で定義される通りであり、Ｌ^１およびＬ^２は、それぞれ互いに独立に、ＨまたはＦである。これらの化合物において、Ｒ^１は、特に好ましくは、１〜８個の炭素原子を有するアルキルまたはアルコキシである。

In the formula, R ¹ is as defined in formula I, and L ¹ and L ² are each independently H or F. In these compounds, R ¹ is particularly preferably alkyl or alkoxy having 1 to 8 carbon atoms.

Especially preferred are mixtures comprising one or more compounds selected from the group consisting of formulas Ia, Ib and Ie, in particular those in which L ¹ and / or L ² is F.

Furthermore, mixtures comprising one or more compounds of the formula If where L ² is H and L ¹ is H or F, in particular F are preferred.

Particular preference is given to compounds of the formula II in which one or both of L ¹ and L ² represents F.

  The compound of formula II is preferably selected from the following formulae:

式中、Ｒ^１は式ＩＩ中で定義される通りで、特に好ましくは、１〜８個の炭素原子を有するｎ−アルキルまたは２〜７個の炭素原子を有するアルケニルである。式ＩＩａの化合物が特に好ましい。

In which R ¹ is as defined in formula II, particularly preferably n-alkyl having 1 to 8 carbon atoms or alkenyl having 2 to 7 carbon atoms. Particular preference is given to compounds of the formula IIa.

  The compound of formula III is preferably selected from the following formulae:

式中、Ｒ^１およびＲ^２は上で定義される通りである。これらの化合物中、Ｒ^１およびＲ^２は、特に好ましくは、１〜８個の炭素原子を有するアルキルまたはアルコキシである。

In which R ¹ and R ² are as defined above. In these compounds, R ¹ and R ² are particularly preferably alkyl or alkoxy having 1 to 8 carbon atoms.

  Particular preference is given to compounds of the formulas IIIa, IIIb and IIIe.

  The mixture according to the invention is preferably one or more compounds selected from the group consisting of the bicyclic compounds of the following formula in addition to the compounds of the formulas I, II and III:

および／または以下の式の三環式化合物からなる群より選ばれる１種類以上の化合物：

And / or one or more compounds selected from the group consisting of tricyclic compounds of the following formula:

および／または以下の式の四環式化合物からなる群より選ばれる１種類以上の化合物：

And / or one or more compounds selected from the group consisting of tetracyclic compounds of the following formula:

を含む。

including.

In which R ¹ and R ² each independently have one of the meanings indicated for R ^{1 in} formula I, preferably each independently 1 to 12 carbon atoms. An alkyl, alkoxy or alkenyl group, but in addition, one or two non-adjacent CH ₂ groups can be defined as —O—, —CH═CH—, —, such that the O atoms are not directly bonded to each other. C≡C—, —CO—, —OCO— or —COO— may be substituted, and L ¹ is H or F.

  Further, the 1,4-phenylene groups in IV10 to IV19 and IV23 to IV26 may be independently monosubstituted or polysubstituted by fluorine independently of each other.

Particular preference is given to compounds of the formulas IV27 to IV33, each having 1 to 7 carbon atoms, wherein R ¹ is alkyl and R ² is alkyl or alkoxy. Furthermore, compounds of formulas IV25 and IV31 in which L ¹ is F are preferred. Very particular preference is given to compounds of the formulas IV6, IV26, IV27 and IV32.

R ¹ and R ^{2 in} the compounds of the formulas IV1 to IV33 are particularly preferably straight-chain alkyl or alkoxy having 1 to 12 carbon atoms.

  The mixture according to the invention preferably comprises, in addition to the compounds of formulas I, II and III, one or more alkenyl compounds selected from formulas V1 and V2.

式中、
Ａ^４は、１，４−フェニレンまたはトランス−１，４−シクロヘキシレンであり、
ｃは、０または１であり、
Ｒ^３は、２〜７個の炭素原子を有するアルケニル基であり、
Ｒ^４は、１〜１２個の炭素原子を有するアルキル、アルコキシまたはアルケニル基であり、ただし、１個または２個の隣接していないＣＨ_２基は、酸素原子が互いに直接結合しないようにして、−Ｏ−、−ＣＨ＝ＣＨ−、−Ｃ≡Ｃ−、−ＣＯ−、−ＯＣＯ−または−ＣＯＯ−で置き換えられていてもよく、
Ｑは、ＣＦ_２、ＯＣＦ_２、ＣＦＨ、ＯＣＦＨまたは単結合であり、
Ｙは、ＦまたはＣｌであり、および
Ｌ^１およびＬ^２は、それぞれ互いに独立に、ＨまたはＦである。

Where
A ⁴ is 1,4-phenylene or trans-1,4-cyclohexylene,
c is 0 or 1,
R ³ is an alkenyl group having 2 to 7 carbon atoms,
R ⁴ is an alkyl, alkoxy or alkenyl group having 1 to 12 carbon atoms, provided that one or two non-adjacent CH ₂ groups are such that oxygen atoms are not directly bonded to each other, -O-, -CH = CH-, -C≡C-, -CO-, -OCO- or -COO- may be substituted,
Q is CF ₂ , OCF ₂ , CFH, OCFH or a single bond,
Y is F or Cl, and L ¹ and L ² are each independently H or F.

  Particular preference is given to compounds of the formula V1 in which c is 1. More preferred are compounds of formula V1 selected from the following formulae:

式中、Ｒ^３ａおよびＲ^４ａは、それぞれ互いに独立に、Ｈ、ＣＨ_３、Ｃ_２Ｈ_５またはｎ−Ｃ_３Ｈ_７であり、ａｌｋｙｌは、１〜８個の炭素原子を有するアルキル基である。

In the formula, R ^3a and R ^4a are each independently H, CH ₃ , C ₂ H ₅ or n-C ₃ H ₇ , and alkyl is an alkyl group having 1 to 8 carbon atoms. .

Compounds of formula V1a, especially those in which R ^3a and R ^4a are CH ₃ , compounds of formula V1e, especially those in which R ^3a is H, and compounds of formula V1f, V1g, V1h and V1i, in particular R ^3a is H or CH ₃ Are particularly preferred.

Particularly preferred compounds of the formula V2 are those in which L ¹ and / or L ² are F and Q—Y is F or OCF ₃ . Further preferred compounds of the formula V2 are those in which R ³ has 2 to 7 carbon atoms, in particular 1E-alkenyl or 3E-alkenyl having 2, 3 or 4 carbon atoms. Further preferred compounds of formula V2 are those of formula V2a.

式中、Ｒ^３ａは、Ｈ、ＣＨ_３、Ｃ_２Ｈ_５またはｎ−Ｃ_３Ｈ_７、特にＨまたはＣＨ_３である。

In which R ^3a is H, CH ₃ , C ₂ H ₅ or n-C ₃ H ₇ , in particular H or CH ₃ .

  By using the compounds of the formulas V1 and V2, liquid crystal mixtures according to the invention having a particularly low rotational viscosity value and CLC displays having a fast response time, especially at low temperatures, are achieved.

  In other preferred embodiments, the mixtures according to the invention preferably comprise one or more compounds of the formulas VI1 and / or VI2 in addition to the compounds of the formulas I, II and III.

式中、
Ａ^５は、３位および／または５位がフッ素化されていてもよい１，４−フェニレン、またはトランス−１，４−シクロヘキシレンであり、
Ｒ^５は、１〜１２個の炭素原子を有するアルキル、アルコキシまたはアルケニル基であり、ただし、１個または２個の隣接していないＣＨ_２基は、酸素原子が互いに直接結合しないようにして、−Ｏ−、−ＣＨ＝ＣＨ−、−Ｃ≡Ｃ−、−ＣＯ−、−ＯＣＯ−または−ＣＯＯ−で置き換えられていてもよく、
Ｑは、ＣＦ_２、ＯＣＦ_２、ＣＦＨ、ＯＣＦＨまたは単結合であり、
Ｙは、ＦまたはＣｌであり、および
Ｌ^１およびＬ^２は、それぞれ互いに独立に、ＨまたはＦである。

Where
A ⁵ is 1,4-phenylene or trans-1,4-cyclohexylene which may be fluorinated at the 3-position and / or 5-position,
R ⁵ is an alkyl, alkoxy or alkenyl group having 1 to 12 carbon atoms, provided that one or two non-adjacent CH ₂ groups are such that oxygen atoms are not directly bonded to one another, -O-, -CH = CH-, -C≡C-, -CO-, -OCO- or -COO- may be substituted,
Q is CF ₂ , OCF ₂ , CFH, OCFH or a single bond,
Y is F or Cl, and L ¹ and L ² are each independently H or F.

Compounds of formula VI1 and VI2 A ⁵ is 1,4-phenylene are particularly preferred.

  More preferred are compounds of formula VI1 and VI2 selected from the following formulae:

式中、Ｒ^５は上において式ＶＩ１中で定義される通りであり、好ましくは、１〜８個の炭素原子を有するアルキルまたはアルコキシである。

In which R ⁵ is as defined above in formula VI1 and is preferably alkyl or alkoxy having 1 to 8 carbon atoms.

  Particular preference is given to compounds of the formulas VI1a and VI2b.

  With the compounds of the formulas VI1 and VI2, an increase in birefringence in the medium according to the invention is achieved in particular. In particular, the compound of formula VI2 increases the birefringence while maintaining a low viscosity.

In a particularly preferred embodiment, the nematic component of the medium according to the invention comprises one or more of the following:
One or more compounds of the formula Ib, wherein L ¹ is F and L ² is H,
One or more compounds of formula Ie, wherein L ¹ is F and L ² is H;
One or more compounds of the formula IIa,
One or more compounds of the formula IIIe,
More than -30%, preferably more than 40%, very preferably more than 50%, one or more compounds of the formula I,
-5 to 80%, preferably 10 to 70% of one or more compounds of the formula I,
-8-65%, preferably 15-55% of one or more compounds of formula Ib,
-3 to 45%, preferably 5 to 30% of one or more compounds of formula Ie,
From 2 to 35%, preferably from 5 to 25% of one or more compounds of formula II, very preferably of formula IIa,
-5 to 60%, preferably 10 to 50% of one or more compounds of formula III, very preferably of formula IIIe.
In a further particularly preferred embodiment, the nematic component consists essentially of a compound selected from formulas I, II and III.

By appropriate selection of the end groups R ^1-5 and QY in the compounds of formulas I-VI2, the address time, threshold voltage and further properties can be changed in the desired manner. For example, 1E-alkenyl groups, 3E-alkenyl groups, 2E-alkenyloxy groups and the like generally result in shorter address times, improved nematic tendencies, and elasticity compared to alkyl or alkoxy groups. The ratio of the constants K ₃ (bend) and K ₁ (spray) is higher. 4-Alkenyl groups and 3-alkenyl groups generally provide lower threshold voltages and smaller values of K ₃ / K ₁ compared to alkyl and alkoxy groups.

The —CH ₂ CH ₂ — group in the elements Z ¹ , Z ² and Z ³ of the bridge structure generally results in a higher ratio of elastic constants K ₃ / K ₁ compared to single covalent bonds. It becomes. Higher values of K ₃ / K ₁ facilitate shorter reflection wavelengths without changing dopant concentration, for example, due to higher HTP.

  The optimum mixing ratio of the individual compounds of formulas I to VI2 depends substantially on the properties desired, the choice of compounds of formulas I to VI2 and the choice of further compounds that may be present. Appropriate mixing ratios within the above range can easily be determined from case to case.

In the formulas described above and below, the term “fluorinated alkyl or alkoxy having 1 to 3 carbon atoms” is preferably CF ₃ , OCF ₃ , CFH ₂ , OCFH ₂ , CF ₂ H, OCF _2. H, C ₂ F ₅ , OC ₂ F ₅ , CFHCF ₃ , CFHCF ₂ H, CFHCFH ₂ , CH ₂ CF ₃ , CH ₂ CF ₂ H, CH ₂ CFH ₂ , CF ₂ CF ₂ H, CF ₂ CFH ₂ , OCHFCF ₃ , OCHFHCF ₂ H, OCHFHCHF ₂ , OCH ₂ CF ₃ , OCH ₂ CF ₂ H, OCH ₂ CFH ₂ , OCF ₂ CF ₂ H, OCF ₂ CFH ₂ , C ₃ F ₇ or OC ₃ F ₇ , especially CF ₃ , OCF ₃ , CF ₂ H, OCF ₂ H, C ₂ F ₅ , OC ₂ F ₅ , CFHCF ₃ , CFHCF ₂ H, CFHCHF ₂ , CF ₂ CF ₂ H, CF ₂ CFH ₂ , OCFHCF ₃ , OCFHCF ₂ H, OCFHCHFH ₂ , OCF ₂ CF ₂ H, OCF ₂ CFH ₂ , C ₃ F ₇ or OC ₃ F ₇ , particularly preferably OCF ₃ or Represents OCF ₂ H.

  The term “alkyl” covers straight-chain and branched alkyl groups having 1 to 7 carbon atoms, especially in the straight-chain groups methyl, ethyl, propyl, butyl, pentyl, hexyl and heptyl. is there. Groups having 2 to 5 carbon atoms are generally preferred.

The term “alkenyl” includes straight-chain and branched alkenyl groups having 2 to 7 carbon atoms, in particular the straight-chain groups. Particularly preferred alkenyl _groups, C _{2 ~C} 7 -1E- _alkenyl, C _{4 ~C} 7 -3E- _alkenyl, C _{5 ~C} 7 -4- _alkenyl, C _{6 ~C} 7 -5- alkenyl and _C 7 -6 - alkenyl, in particular _C 2 _{-C 7-1E-alkenyl,} C ₄ -C 7 -3E-alkenyl and _C 5 _-C 7-4-alkenyl. Examples of preferred alkenyl groups are vinyl, 1E-propenyl, 1E-butenyl, 1E-pentenyl, 1E-hexenyl, 1E-heptenyl, 3-butenyl, 3E-pentenyl, 3E-hexenyl, 3E-heptenyl, 4-pentenyl, 4Z -Hexenyl, 4E-hexenyl, 4Z-heptenyl, 5-hexenyl, 6-heptenyl and the like. Groups having up to 5 carbon atoms are generally preferred.

  The term “fluoroalkyl” preferably covers linear groups with terminal fluorine, ie fluoromethyl, 2-fluoroethyl, 3-fluoropropyl, 4-fluorobutyl, 5-fluoropentyl, 6-fluoro. Hexyl and 7-fluoroheptyl. However, fluorine at other positions is not excluded.

The term “oxaalkyl” preferably covers a straight-chain group of formula C _n H _{2n + 1} —O— (CH ₂ ) _m , wherein n and m are each independently 1 to 6 is there. Preferably, n = 1 and m is 1-6.

  Halogen is preferably F or Cl, in particular F.

  When one of the above groups is an alkyl group and / or an alkoxy group, this may be either linear or branched. Preferably it is linear and has 2, 3, 4, 5, 6 or 7 carbon atoms and is therefore preferably ethyl, propyl, butyl, pentyl, hexyl, heptyl, ethoxy, propoxy , Butoxy, pentoxy, hexyloxy or heptyloxy, methyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, methoxy, octyloxy, nonyloxy, decyloxy, undecyloxy, dodecyloxy, tridecyloxy Or tetradecyloxy.

  Oxaalkyl is preferably linear 2-oxapropyl (ie methoxymethyl), 2- (ie ethoxymethyl) or 3-oxabutyl (ie 2-methoxyethyl), 2-, 3- or 4 -Oxapentyl, 2-, 3-, 4- or 5-oxahexyl, 2-, 3-, 4-, 5- or 6-oxaheptyl, 2-, 3-, 4-, 5-, 6- or 7-oxaoctyl, 2-, 3-, 4-, 5-, 6-, 7- or 8-oxanonyl, or 2-, 3-, 4-, 5-, 6-, 7-, 8- or 9 -Oxadecyl.

When one of the above groups is an alkyl group in which one CH ₂ group is replaced by —CH═CH—, this may be either linear or branched. Preferably it is straight-chain and has 2 to 10 carbon atoms. Thus, in particular, it is vinyl, prop-1- or -2-enyl, but-1-, -2- or -3-enyl, penta-1-, -2-, -3- or -4-enyl, hexa -1-, -2-, -3-, -4- or -5-enyl, hepta-1-, -2-, -3-, -4-, -5, or -6-enyl, octa-1 -, -2-, -3-, -4-, -5, -6, or -7-enyl, nona-1-, -2-, -3-, -4-, -5, -6 -, -7- or -8-enyl, or deca-1-, -2-, -3-, -4-, -5, -6, -7-, -8- or -9-enyl is there.

When one of the above groups is an alkyl group in which one CH ₂ group is replaced by —O— and one is replaced by —CO—, these are preferably adjacent. They therefore contain an acyloxy group —CO—O— or an oxycarbonyl group —O—CO. These are preferably straight-chain and have 2 to 6 carbon atoms.

  Thus, they are in particular acetoxy, propionyloxy, butyryloxy, pentanoyloxy, hexanoyloxy, acetoxymethyl, propionyloxymethyl, butyryloxymethyl, pentanoyloxymethyl, 2-acetoxyethyl, 2-propionyloxyethyl, 2-butyryloxyethyl, 3-acetoxypropyl, 3-propionyloxypropyl, 4-acetoxybutyl, methoxycarbonyl, ethoxycarbonyl, propoxycarbonyl, butoxycarbonyl, pentoxycarbonyl, methoxycarbonylmethyl, ethoxycarbonylmethyl, propoxycarbonylmethyl , Butoxycarbonylmethyl, 2- (methoxycarbonyl) ethyl, 2- (ethoxycarbonyl) ethyl, 2- (propoxycarbonyl) Chill, 3- (methoxycarbonyl) propyl, 3- (ethoxycarbonyl) propyl or 4- (methoxycarbonyl) - butyl.

One of the above groups is an alkyl in which one CH ₂ group is replaced by —CH═CH—, unsubstituted or substituted, and the adjacent CH ₂ group is replaced by CO or CO—O or O—CO In the case of a group, this may be either linear or branched. It is preferably straight-chain and has 4 to 13 carbon atoms. Thus, it is notably acryloyloxymethyl, 2-acryloyloxyethyl, 3-acryloyloxypropyl, 4-acryloyloxybutyl, 5-acryloyloxypentyl, 6-acryloyloxyhexyl, 7-acryloyloxyheptyl, 8-acryloyloxy Octyl, 9-acryloyloxynonyl, 10-acryloyloxydecyl, methacryloyloxymethyl, 2-methacryloyloxyethyl, 3-methacryloyloxypropyl, 4-methacryloyloxybutyl, 5-methacryloyloxypentyl, 6-methacryloyloxyhexyl, 7- Methacryloyloxyheptyl, 8-methacryloyloxyoctyl or 9-methacryloyloxynonyl.

When one of the above groups is an alkyl or alkenyl group that is monosubstituted by CN or CF ₃ , this group is preferably linear. Substitution with CN or CF ₃ is at any desired position.

  When one of the above groups is an alkyl or alkenyl group that is at least monosubstituted by halogen, this group is preferably straight-chain and the halogen is preferably F or Cl. In the case of polysubstitution, the halogen is preferably F. The resulting group also includes perfluorinated groups. In the case of monosubstitution, the fluorine or chlorine substituent can be in any desired position, but is preferably in the ω position.

  Compounds containing branched and winged groups are often important because of better solubility in conventional liquid crystal base materials. However, they are particularly important as chiral dopants if they are optically active.

  This type of branched group generally does not have more than one chain branch. Preferred branched groups are isopropyl, 2-butyl (ie 1-methylpropyl), isobutyl (ie 2-methylpropyl), 2-methylbutyl, isopentyl (ie 3-methylbutyl), 2-methylpentyl, 3 -Methylpentyl, 2-ethylhexyl, 2-propylpentyl, isopropoxy, 2-methylpropoxy, 2-methylbutoxy, 3-methylbutoxy, 2-methylpentoxy, 3-methylpentoxy, 2-ethylhexyloxy, 1- Methylhexyloxy and 1-methylheptyloxy.

When one of the above groups is an alkyl group in which two or more CH ₂ groups are replaced by —O— and / or —CO—O—, this may be either linear or branched. It is preferably branched and has 3 to 12 carbon atoms. Thus, it is in particular biscarboxymethyl, 2,2-biscarboxyethyl, 3,3-biscarboxypropyl, 4,4-biscarboxybutyl, 5,5-biscarboxypentyl, 6,6-biscarboxyhexyl, 7,7-biscarboxyheptyl, 8,8-biscarboxyoctyl, 9,9-biscarboxynonyl, 10,10-biscarboxydecyl, bis (methoxycarbonyl) methyl, 2,2-bis (methoxycarbonyl) ethyl, 3,3-bis (methoxycarbonyl) propyl, 4,4-bis (methoxycarbonyl) butyl, 5,5-bis (methoxycarbonyl) pentyl, 6,6-bis (methoxycarbonyl) hexyl, 7,7-bis ( Methoxycarbonyl) heptyl, 8,8-bis (methoxycarbonyl) octyl, Sus (ethoxycarbonyl) methyl, 2,2-bis (ethoxycarbonyl) ethyl, 3,3-bis (ethoxycarbonyl) propyl, 4,4-bis (ethoxycarbonyl) butyl or 5,5-bis (ethoxycarbonyl) pentyl It is.

  The optically active component of the CLC medium according to the present invention comprises one or more chiral dopants whose helical twist force and concentration are selected such that the helical pitch of the LC medium is 1 μm or less.

  The proportion of the optically active component in the CLC medium according to the invention is preferably 20% or less, in particular 10% or less, particularly preferably 0.01 to 7%, very particularly preferably 0.1 to 5%. The optically active component preferably comprises 1 to 6, in particular 1, 2, 3 or 4 chiral dopants.

  The chiral dopant should preferably have a high helical twist force (HTP) and a low temperature dependence. Furthermore, the chiral dopant must have good solubility in the nematic component and must not impair or only to a lesser extent the liquid crystal properties of the LC medium. The chiral dopant may have either the same or opposite rotational direction and may have either the same or opposite temperature dependence of the twist.

Particularly preferred are chiral dopants having an HTP of 20 μm ⁻¹ or more, in particular 40 μm ⁻¹ or more, particularly preferably 70 μm ⁻¹ or more.

  For optically active components, such as, for example, cholesteryl nonanoate, R / S-811, R / S-1011, R / S-2011, R / S-3011 or CB15 (available from Merck, Darmstadt) Numerous chiral dopants, some commercially available, are available to those skilled in the art.

  Particularly suitable dopants are compounds comprising one or more chiral groups and one or more aromatic or alicyclic groups which together with one or more mesogenic groups or chiral groups form a mesogenic group.

  Suitable chiral groups are, for example, chiral branched hydrocarbon groups, chiral ethanediols, binaphthols or dioxolanes, as well as sugar derivatives, sugar alcohols, sugar acids, lactic acids, chiral substituted glycols , A steroid derivative, a terpene derivative, an amino acid, or a monovalent or polyvalent chiral group selected from the group consisting of a few, preferably 1-5 amino acid sequences.

Preferred chiral groups are sugar derivatives such as glucose, mannose, galactose, fructose, arabinose and dextrose; sugar alcohols such as sorbitol, mannitol, iditol, galactitol or their anhydrous derivatives, in particular dianhydrosorbide (1,4 : Dianhydrohexitols such as 3,6-dianhydro-D-sorbide and isosorbide), dianhydromannitol (isosorbitol) or dianhydroiditol (isoiditol); Acids; for example, chiral substituted glycol groups such as mono- or oligoethylene or propylene glycol in which one or more CH ₂ groups are substituted by alkyl or alkoxy; Amino acids such as valine, phenylglycine or phenylalanine or sequences of 1 to 5 of these amino acids, etc .; steroid derivatives such as cholesteryl or cholic acid groups; for example menthyl, neomenthyl, camphoryl, pinail, terpineil, isolongifolyl, Terpene derivatives such as fenkyl, kaleyl, mirtenyl, nopyr, geraniyl, linaroyl, neryl, citronellyl or dihydrocitronellyl.

  Suitable chiral groups and mesogenic chiral compounds are described, for example, in German Patent No. 34 25 503, German Patent No. 35 34 777, German Patent No. 35 34 778, German Patent No. 35 34 779 and German Patent 35 34 780, German Patent Application Publication No. 43 42 280, European Patent Application Publication No. 1 038 941 and European Patent Application Publication No. 195 41 820. It is described in the publication.

  Particularly preferred are chiral dopants selected from the group comprising compounds of the following formula:

更に好ましいキラルドーパントは、以下の式のイソソルビド、イソマンニトールまたはイソイジトールの誘導体：

More preferred chiral dopants are isosorbide, isomannitol or isoiditol derivatives of the following formula:

であり、式中、

Where

そして、好ましくは、ジアンヒドロソルビトールであり、
および、例えばジフェニルエタンジオール（ヒドロベンゾイン）などのキラルなエタンジオール類で、特に以下の式：

And, preferably, dianhydrosorbitol,
And chiral ethanediols such as, for example, diphenylethanediol (hydrobenzoin), in particular:

のメソゲン性ヒドロベンゾイン誘導体（示していない（Ｒ，Ｓ）、（Ｓ，Ｒ）、（Ｒ，Ｒ）および（Ｓ，Ｓ）鏡像体を含む。）であり、

A mesogenic hydrobenzoin derivative (including (R, S), (S, R), (R, R) and (S, S) enantiomers not shown);

Where
B and C are each independently 1,4-phenylene or 1,4-cyclohexylene optionally monosubstituted, disubstituted or trisubstituted by L;
L is H, F, Cl, CN or an optionally halogenated alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having 1 to 7 carbon atoms;
b is 0, 1 or 2;
c is 0 or 1,
Z ⁵ is —COO—, —OCO—, —CH ₂ CH ₂ — or a single bond, and R ⁵ is alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl or alkylcarbonyl having 1 to 12 carbon atoms. It is oxy.

  Compounds of formula XII are described in WO 98/00428. Formula XIII compounds are described in GB 2 328 207 A1.

  Very particularly preferred dopants are chiral binaphthyl derivatives as described in WO02 / 94805, chiral binaphthol acetal derivatives as described in WO02 / 34739, WO02 / 94805. Chiral TADDOL derivatives as described in the 06/06265 and at least one fluorinated bridging group as described in WO 02/06196 and WO 02/06195 And a chiral dopant containing a terminal or central chiral group.

  Particularly preferred are chiral binaphthyl derivatives of the formula

特に、以下の式より選択されるもの：

In particular, selected from the following formula:

が好ましい。
式中、Ｂ、ｂ、Ｒ^５およびＺ^５は、式ＸＩＩ中で定義される通りで、Ｚ^５は、特に−ＯＣＯ−または単結合である。

Is preferred.
In which B, b, R ⁵ and Z ⁵ are as defined in formula XII, Z ⁵ being in particular —OCO— or a single bond.

  Particularly preferred are dopants of the following formula:

特に好ましい実施形態において、本発明による媒体の光学活性成分は以下の１つ、
−式ＶＩＩ〜ＸＩＩＩから選択される１種類以上のドーパント、
−式ＸＩＶの１種類以上のドーパント、
−混合物全体（即ち、ネマチックおよび光学活性成分の質量による割合の合計）の好ましくは８％未満、特に５％未満の割合の、好ましくは式ＸＩＶより選択される１種類より多くないドーパント
を含む。

In a particularly preferred embodiment, the optically active component of the medium according to the invention is one of the following:
One or more dopants selected from formulas VII-XIII,
One or more dopants of the formula XIV,
-Preferably less than 8%, in particular less than 5% of the total mixture (ie the sum of the proportions of nematic and optically active components by weight), preferably not more than one dopant selected from the formula XIV.

  In a further particularly preferred embodiment, the medium according to the invention comprises 20% or less, in particular 0.01 to 10% of optically active component.

  In particular, the chiral dopants of the above formulas XII, XIII and XIV have good solubility in the nematic component and induce a high twist and a cholesteric structure with a helical pitch and a low temperature dependence of the reflection wavelength. Even when only one of these dopants is used in small amounts, it achieves a CLC medium according to the invention having a reflection color in the high luminance and low temperature dependent visual wavelength range, which is particularly suitable for use in SSCT and PSCT displays Is possible.

  This is an important advantage over the CLC media from the prior art, which in the prior art usually has the same rotational twist and opposite temperature dependence to achieve temperature compensation of the reflected wavelength. There is a need for at least two types of dopants (e.g., one that has a positive temperature dependence, i.e., one that increases in twist with increasing temperature and one that has a negative temperature dependence). In addition, a large amount of dopant is often required in known CLC media to achieve reflection in the visible region.

  Accordingly, particularly preferred embodiments of the present invention relate to CLC media and CLC displays containing this media, and as described above and below, the chiral component contains no more than one chiral compound, preferably in an amount of less than 15%. In particular, less than 10%, particularly preferably 5% or less. The chiral compounds in these media are particularly preferably WO 02/94805, WO 02/34739, WO 02/06265, WO 02/06196 and WO Selected from the compounds described in publication 02/06195 and formulas VII-XIV (including preferred sub-formulas thereof). The CLC medium of this preferred embodiment has a low dependence of the reflection wavelength λ on the temperature T over a wide temperature range.

  The helical pitch of the medium is preferably 130 nm to 1000 nm, in particular 200 nm to 750 nm, particularly preferably 300 nm to 450 nm.

  Preferably, the helical pitch is selected so that the medium reflects light in the visible wavelength range. The term “visible wavelength range” or “visible spectrum” typically covers the wavelength range of 400-800 nm. However, above and below, the term is intended to cover the 200-1200 nm wavelength range, including the UV and infrared (IR) ranges, and the far UV and far IR ranges.

  The reflection wavelength of the LC medium according to the invention is preferably in the range from 200 to 1500 nm, in particular from 300 to 1200 nm, particularly preferably from 350 to 900 nm, very particularly preferably from 400 to 800 nm. Furthermore, LC media having a reflection wavelength of 400 to 700 nm, especially 400 to 600 nm are preferred.

  The wavelength values shown above and below relate to the full width at half maximum of the reflection band, unless explicitly stated otherwise.

  Preferably between 0 and 50 ° C., in particular between −20 and 60 ° C., particularly preferably between −20 and 70 ° C., very particularly preferably from −20 ° C. to 10 ° C. from the clearing point, in particular 5 ° C. A CLC medium according to the invention having a temperature-dependent dλ / dT of 0.6 nm / ° C. or less, in particular 0.3 nm / ° C. or less, very particularly preferably 0.15 nm / ° C. or less in the range up to low temperatures. Particularly preferred.

  Unless otherwise stated, dλ / dT represents the local slope of the function λ (T), where the nonlinear function λ (T) is described for approximation by a second or third order polynomial.

  The invention further relates to the use of the CLC medium according to the invention for electro-optical purposes.

  Furthermore, the invention comprises an electro-optic display containing a CLC medium according to the invention, in particular two planar parallel plates forming a cell with a frame, and a cholesteric liquid crystal mixture disposed in the cell. It also relates to SSCT or PSCT displays.

  Furthermore, the present invention switches an electro-optic active matrix display containing a CLC medium according to the present invention, in particular two planar parallel plates forming cells with the frame, and individual pixels on the plate. The invention relates to an AM-CLC display, preferably an AM-SSCT or PSCT display, having an integrated non-linear device for the purpose and a cholesteric liquid crystal mixture, preferably having a positive dielectric anisotropy and a high resistivity, disposed in the cell.

  Bistable SSCT and PSCT cell structures are described, for example, in WO 92/19695, WO 93/23496, US Pat. No. 5,453,863, or US Pat. No. 5,493,430. It is described in the specification. The structure of the active matrix CLC display is described in, for example, WO 02/086855 pamphlet and US Application Publication No. 2002-0149552.

  The ratio d / p between the layer thickness d (spacing of the outer plates) of the liquid crystal cell and the natural helical pitch p of the CLC medium in the CLC display according to the invention is preferably greater than 1, in particular 2-20. Within the range, particularly preferably 3 to 15, very particularly preferably 4 to 10.

  The CLC medium according to the invention facilitates a significant expansion of the size of the available parameters. Thus, the achievable combinations of reflection wavelength, birefringence, clearing point, viscosity, thermal and UV stability and dielectric anisotropy far exceed the prior materials from the prior art, and the media according to the present invention in CLC displays It is particularly suitable for use.

  The CLC medium according to the invention has a cholesteric phase down to −20 ° C., preferably down to −30 ° C., very preferably down to −40 ° C., and at least 70 ° C., preferably at least 75 ° C., very preferably at least 80 ° C. It preferably has a clearing point of ° C.

  The dielectric anisotropy Δε of the CLC medium is preferably 10 or more, very preferably 20 or more, most preferably 35 or more.

  The birefringence Δn of the CLC medium is preferably 0.15 or more, very preferably 0.20 or more.

  At the same time, the CLC media according to the invention have a low value for viscosity and a high value for resistivity, making it possible to achieve excellent CLC displays, in particular AM-CLC displays. In particular, the mixture is characterized by a low operating voltage.

  Also, it goes without saying that by appropriately selecting the components of the mixture according to the invention, it is possible to achieve a higher clearing point (for example above 120 ° C.) at higher threshold voltages while maintaining other advantageous properties. Or a lower clearing point can be achieved at a lower threshold voltage. Similarly, a mixture with a higher Δε and thus a lower threshold can be obtained with a corresponding slight increase in viscosity.

  The width of the cholesteric phase range is preferably at least 90 ° C., in particular at least 100 ° C. This range preferably extends over at least −20 to + 60 ° C., particularly preferably at least −20 to + 70 ° C., very particularly preferably at least −20 to + 80 ° C.

  Also, the UV stability of the CLC media according to the present invention is significantly better, i.e. they exhibit a significantly smaller change in reflection wavelength and operating voltage when exposed to UV.

  A further preferred embodiment of the invention relates to a CLC medium according to the invention comprising one or more compounds comprising at least one polymerizable group. This type of CLC medium is particularly suitable for use in, for example, polymer gel or PSCT displays. The polymerizable compound can be a constituent of the nematic and / or chiral component or form an additional component of the medium.

  Suitable polymerizable compounds are known to those skilled in the art and are described in the prior art. In addition, the polymerizable compound can be mesogenic or liquid crystalline. They can contain one or more, preferably two polymerizable groups. A typical example of a non-mesogenic compound containing two polymerizable groups is an alkyl diacrylate or alkyl dimethacrylate containing an alkyl group having 1 to 20 carbon atoms. Typical examples of non-mesogenic compounds containing more than two polymerizable groups are trimethylolpropane trimethacrylate and pentaerythritol tetraacrylate. Typical examples of mesogenic or liquid crystalline polymerizable compounds (also known as “reactive mesogens” or “RMs”) are, for example, WO 93/22397, European Patent 0 261 712. German Patent No. 195 04 224, WO 95/22586, WO 97/00600, US Pat. No. 5,518,652, US Pat. 750,051, US Pat. No. 5,770,107 and US Pat. No. 6,514,578. Examples of particularly suitable and preferred RMs are shown in the list below.

式中、
Ｐ^０は複数生じる場合は互いに独立に重合性基であり、好ましくはアクリル、メタクリル、オキセタン、エポキシ、ビニル、ビニルオキシ、プロペニルエーテルまたはスチレン基であり、
Ａ^０およびＢ^０は、複数生じる場合は互いに独立に、１個、２個、３個または４個の基Ｌで置換されていてもよい１，４−フェニレン、または１，４−シクロヘキシレンであり、
Ｚ^０は、複数生じる場合は互いに独立に、−ＣＯＯ−、−ＯＣＯ−、−ＣＨ_２ＣＨ_２−、−Ｃ≡Ｃ−、−ＣＨ＝ＣＨ−、−ＣＨ＝ＣＨ−ＣＯＯ−、−ＯＣＯ−ＣＨ＝ＣＨ−または単結合であり、
Ｒ^０は、１個以上、好ましくは１〜１５個のＣ原子を有し、フッ素化されていてもよいアルキル、アルコキシ、チオアルキル、アルキルカルボニル、アルコキシカルボニル、アルキルカルボニルオキシまたはアルコキシカルボニルオキシであるか、またはＹ^０またはＰ−（ＣＨ_２）_ｙ−（Ｏ）_ｚ−であり、
Ｙ^０は、Ｆ、Ｃｌ、ＣＮ、ＮＯ_２、ＯＣＨ_３、ＯＣＮ、ＳＣＮ、ＳＦ_５、フッ素化されていてもよい１〜４個のＣ原子のアルキルカルボニル、アルコキシカルボニル、アルキルカルボニルオキシまたはアルコキシカルボニルオキシ、モノフッ素化、オリゴフッ素化またはポリフッ素化され１〜４個のＣ原子のアルキルまたはアルコキシであり、
Ｒ^{０１、０２}は、互いに独立に、Ｈ、Ｒ^０またはＹ^０であり、
Ｒ^＊は、２−メチルブチル、２−メチルオクチル、２−メチルブトキシまたは２−メチルオクトキシのような、４個以上、好ましくは４〜１２個のＣ原子を有するキラルなアルキルまたはアルコキシ基であり、
Ｃｈは、メンチルまたはシトロネリルのような、コレステリル、エストラジオールまたはテルペノイド基から選択されるキラル基であり、
Ｌは、複数生じる場合は互いに独立に、Ｈ、Ｆ、Ｃｌ、ＣＮまたはハロゲン化されていてもよい１〜５個のＣ原子のアルキル、アルコキシ、アルキルカルボニル、アルコキシカルボニル、アルキルカルボニルオキシまたはアルコキシカルボニルオキシであり、
ｒは、０、１、２、３または４であり、
ｔは、複数生じる場合は互いに独立に、０、１、２または３であり、
ｕおよびｖは、互いに独立に、０、１または２であり、
ｗは、０または１であり、
ｘおよびｙは、互いに独立に、０または１〜１２の同一または異なる整数であり、
ｚは０または１で、隣接するｘまたはｙが０の場合、ｚは０であり、
ただし、ベンゼンおよびナフタレン環は、加えて、１個以上の同一または異なる基Ｌで置換されていてもよい。

Where
P ⁰ is a polymerizable group independently of one another when it occurs in plural, preferably an acrylic, methacrylic, oxetane, epoxy, vinyl, vinyloxy, propenyl ether or styrene group,
A ⁰ and B ⁰ are independently of each other when they occur, 1,4-phenylene, or 1,4-cyclohexylene, optionally substituted with 1, 2, 3 or 4 groups L Yes,
When a plurality of Z ⁰ are generated, they are independently of each other —COO—, —OCO—, —CH ₂ CH ₂ —, —C≡C—, —CH═CH—, —CH═CH—COO—, —OCO—. CH = CH- or a single bond,
R ⁰ is alkyl, alkoxy, thioalkyl, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy which has 1 or more, preferably 1 to 15 C atoms and may be fluorinated. Or Y ⁰ or P— (CH ₂ ) _y — (O) _z —,
Y ⁰ is F, Cl, CN, NO ₂ , OCH ₃ , OCN, SCN, SF ₅ , alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyl of 1 to 4 C atoms which may be fluorinated. An oxy, monofluorinated, oligofluorinated or polyfluorinated alkyl of 1 to 4 C atoms or alkoxy;
R ^{01 and 02} are independently of each other H, R ⁰ or Y ⁰ ;
R ^* is a chiral alkyl or alkoxy group having 4 or more, preferably 4 to 12 C atoms, such as 2-methylbutyl, 2-methyloctyl, 2-methylbutoxy or 2-methyloctoxy ,
Ch is a chiral group selected from cholesteryl, estradiol or terpenoid groups, such as menthyl or citronellyl,
L is, independently of one another, in the case of multiple occurrences, alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyl of 1 to 5 C atoms, which may be halogenated, H, F, Cl, CN Is oxy,
r is 0, 1, 2, 3 or 4;
t is 0, 1, 2, or 3 independently of each other when a plurality of occurrences occur;
u and v are independently of each other 0, 1 or 2;
w is 0 or 1,
x and y are independently the same or different integers of 0 or 1 to 12,
z is 0 or 1, and when adjacent x or y is 0, z is 0;
However, the benzene and naphthalene rings may additionally be substituted with one or more identical or different groups L.

  CLC media containing one or more polymerizable compounds include, for example, catalysts, sensitizers, stabilizers, inhibitors, chain transfer agents, co-reactive monomers, surface active compounds, lubricants, wetting agents, dispersants. One or more additions, such as hydrophobing agents, tackifiers, flow improvers, antifoaming agents, deaerators, diluents, reactive diluents, auxiliaries, colorants, dyes, pigments or nanoparticles An agent may be additionally included.

  In addition to the compounds of Formulas I-XIV, the CLC medium can contain one or more additional components for the purpose of optimizing various properties.

  The individual compounds of the above and below formulas and their sub-formulas which can be used in the medium according to the invention are known or they can be prepared analogously to known compounds.

  Liquid crystal mixtures that can be used according to the invention are prepared in a manner that is conventional per se. In general, the desired amount of the components used in smaller amounts is dissolved, preferably at elevated temperature, in the components making up the main part. It is also possible to mix a solution of the components in an organic solvent such as acetone, chloroform or methanol and remove the solvent again after mixing, for example by distillation.

  The liquid crystal mixture according to the invention can also contain further additives such as, for example, one or more stabilizers or antioxidants or nanoparticles.

In this application and in the following examples, the structure of the liquid crystal compound is indicated using an acronym and the conversion to the chemical formula is performed according to Tables A and B below. All groups C _n H _{2n + 1} and C _m H _{2m + 1} are linear alkyl groups having n and m carbon atoms, respectively. The codes in Table B are self explanatory. In Table A, only the initials for the parent structure are shown. In each case, the initial for the parent structure is followed by a code for the substituents R ¹ , R ² , L ¹ , L ² and L ³ , separated by a dash.

好ましい混合物成分を、表Ａ、ＢおよびＣに示す。

Preferred mixture components are shown in Tables A, B and C.

ＬＣ混合物に適する安定剤および酸化防止剤を、下に述べる（ｎ＝０〜１０、末端メチル基は示していない）：

Suitable stabilizers and antioxidants for the LC mixture are described below (n = 0-10, terminal methyl groups not shown):

上および下において、パーセンテージは質量パーセントである。全ての温度は、摂氏度で与えられる。ｍ．ｐ．は融点を表し、ｃｌ．ｐ．は透明点である。更に、Ｃは結晶状態、Ｓはスメクチック相、Ｎはネマチック相、Ｃｈはコレステリック相およびＩは等方相である。これらの記号間のデータは、転移温度を表す。

Above and below, percentages are percent by weight. All temperatures are given in degrees Celsius. m. p. Represents the melting point, cl. p. Is the clearing point. Furthermore, C is a crystalline state, S is a smectic phase, N is a nematic phase, Ch is a cholesteric phase, and I is an isotropic phase. The data between these symbols represents the transition temperature.

In addition, the following abbreviations are used:
Rotation at 20 ° C. Unless stated dielectric anisotropy ε _‖ parallel to the long axis dielectric constant gamma ₁ other molecules in the extraordinary refractive index [Delta] [epsilon] 20 ° C. in an optical anisotropy n _e 589 nm and 20 ° C. in [Delta] n 589 nm and 20 ° C. Viscosity (mPa · sec)
λ Reflection wavelength at 20 ° C unless otherwise stated (nm)
Δλ Maximum change in reflected wavelength (nm) in the indicated temperature range between −20 and + 70 ° C. unless otherwise stated.

The helical twist force (HTP) of a chiral compound that generates a helical twist superstructure in the liquid crystal mixture is given by the formula HTP = (p · c) ⁻¹ (μm ⁻¹ ), where p is the helical of the helical twist phase The pitch is expressed in μm and c represents the concentration of the chiral compound (a value of 0.01 for c corresponds, for example, to a concentration of 1% by weight). Unless stated otherwise, the upper and lower HTP values relate to a temperature of 20 ° C. and a commercially available neutral nematic TN host mixture MLC-6260 (Merck, Darmstadt).

  Physical parameters are described in “Licristal, Physical Properties of Liquid Crystals, Description of the measurement methods”, W.M. Determined experimentally as described in Becker Edit, Merck, Darmstadt City, Revised Edition, 1998.

  Unless expressly indicated otherwise, terms used herein in the plural are to be interpreted herein as including the singular and vice versa.

  Throughout the description and claims, the terms “comprise” and “contain” and derivatives such as “comprising” and “comprises” are not limiting. Means “included but not limited to” and is not intended to exclude (not exclude) other components.

  It will be appreciated that variations to the foregoing embodiments of the invention are possible while still falling within the scope of the invention. Unless expressly stated otherwise, each feature disclosed in this specification may be replaced by an alternative feature serving the same, equivalent, or similar purpose. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

  All the features disclosed herein can be combined in any combination, except at least some of such features and / or steps are mutually exclusive. In particular, the preferred features of the invention are applicable to all aspects of the invention and may be used in any combination. Similarly, features described in non-essential combinations can be used separately (without combinations).

  The present invention will now be described in more detail with reference to the following examples, which do not limit the scope of the invention but merely illustrate the invention.

<Example 1>
A nematic mixture N1 is prepared as follows.

混合物は非常に高い正の誘電異方性、高い複屈折、および高い透明点を有し、低い閾電圧のＳＳＣＴディスプレイ用のＣＬＣ混合物におけるネマチック成分として使用するのに適している。

The mixture has a very high positive dielectric anisotropy, a high birefringence, and a high clearing point and is suitable for use as a nematic component in CLC mixtures for low threshold voltage SSCT displays.

<Example 2>
A CLC mixture C1 consisting of 97.13% of the nematic mixture N1 of Example 1 and 2.87% of the chiral dopant S-5011 of the following formula is prepared:

ＣＬＣ混合物Ｃ１は４５７ｎｍの反射波長λを有し、ＳＳＣＴディスプレイにおける使用に適している。

CLC mixture C1 has a reflection wavelength λ of 457 nm and is suitable for use in SSCT displays.

Claims (16)

A liquid crystal medium having a helical twist structure and including a nematic component and an optically active component,
The optically active component includes one or more chiral compounds whose helical twist force and concentration are selected such that the helical pitch of the medium is 1 μm or less,
The nematic component has the formula I:

One or more compounds exceeding 40% of
Formula II:

One or more compounds of
Formula III:

A liquid crystal medium comprising one or more compounds of the formula:
R ¹ and R ² are each independently of one another H or an alkyl or alkenyl group having 1 to 20 carbon atoms, which group is unsubstituted or monosubstituted by CN or CF ₃ , Or at least monosubstituted by halogen, and one or more CH ₂ groups in these groups are each independently of each other —O—, —S—, so that the O atoms are not directly bonded to each other. May be substituted by —CO—, —CO—O—, —O—CO—, —O—CO—O—, —CH═CH— or —C≡C—,

Z ¹ is —COO—, —CH ₂ CH ₂ — or a single bond,
Z ² is —COO—, —CH ₂ CH ₂ — or a single bond,
L ^1-5 are each independently H or F,
a and b are each independently 0 or 1; ). The medium of claim 1, comprising more than 50% of one or more compounds of formula I. The medium according to claim 1 or 2, wherein the concentration of the chiral compound relative to the sum of the nematic component and the optically active component is less than 8%. 4. The medium according to claim 3, wherein the concentration of the chiral compound relative to the sum of the nematic component and the optically active component is less than 5%. The helical twisting force of chiral compounds is 20 μm ^-1 It is the above, The medium of any one of Claims 1-4 characterized by the above-mentioned. The helical twisting force of chiral compounds is 40 μm ^-1 The medium according to claim 5, which is described above. The helical twisting force of chiral compounds is 70 μm ^-1 The medium according to claim 6, which is described above. The medium according to any one of claims 1 to 7, comprising at least one compound selected from the following formulae.

(Wherein R ¹ , L ¹ and L ² are as defined in claim 1). The medium according to any one of claims 1 to 8, comprising one or more compounds selected from the following formulae.

Wherein R ¹ is as defined in claim 1. Medium according to any one of claims 1-9, characterized in that it comprises one or more compounds selected from the following formulas

(Wherein R ¹ and R ² , independently of one another, have one of the meanings given in claim 1). The medium according to any one of claims 1 to 10, comprising one or more chiral compounds of the following formulae:

(Where
B is 1,4-phenylene or 1,4-cyclohexylene optionally monosubstituted, disubstituted or trisubstituted by L;
L is H, F, Cl, CN or an optionally halogenated alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having 1 to 7 carbon atoms;
b is 0, 1 or 2;
Z ⁵ is —COO—, —OCO—, —CH ₂ CH ₂ — or a single bond, and R ⁵ is alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl or alkylcarbonyl having 1 to 12 carbon atoms. It is oxy. ) The nematic component is
- one or more compounds 40 to 80% of the formula I,
-2 to 35% of one or more compounds of formula II;
-5 to 60% of one or more compounds of formula III,
The medium according to any one of claims 1 to 11 , characterized by comprising: The medium according to claim 1 , wherein the medium has a reflection wavelength in the range of 400 to 800 nm. Use of a medium according to any one of claims 1 to 13 for electro-optical purposes. An electro-optical liquid crystal display containing the medium according to any one of claims 1 to 13 . The electro-optic liquid crystal display according to claim 15 , which is a cholesteric, SSCT or PSCT display.