KR20110058860A - Liquid crystalline medium and liquid crystal display - Google Patents

Abstract

The present invention relates to compounds of formula I, one or two or three compounds and one or more compounds selected from the group of compounds II and III, and optionally one or more compounds selected from the group of compounds IV and V, wherein Having a meaning as claimed in claim 1, and optionally comprising at least one chiral dopant, and a liquid crystal display, in particular a TN-display, in particular an active matrix display comprising said medium. .

Description

LIQUID CRYSTALLINE MEDIUM AND LIQUID CRYSTAL DISPLAY}

The present invention relates to a liquid crystal medium, preferably a genetically positive nematic medium comprising at least one genetically positive compound and at least one genetically neutral compound, comprising at least one chiral dopant and preferably encapsulated in a polymer matrix, and A liquid crystal display comprising the medium, in particular a display operated in reflective mode and preferably addressed by an active matrix.

Liquid crystal displays (LCDs) are widely used to display information. LCDs are used in direct view displays and projection displays. The electro-optic approach used in most displays is still a twisted nematic (TN) approach and its various variations. In addition to the above schemes, super twisted nematic (STN) schemes and more recently optically compensated bend (OCB) schemes and electrically controlled birefringence (ECB) schemes and various variants thereof, such as vertically aligned nematic (VAN) patterns ITO vertically aligned nematic (PVA) schemes and polymer stabilized vertically aligned nematic (PSVA) schemes and multi-domain vertically aligned nematic (MVA) schemes and others are increasingly being used. All these approaches use an electric field that is substantially perpendicular to the substrate or liquid crystal layer. In addition to these schemes, the substrate or liquid crystal layer is substantially applied to the in-plane switching (abbreviated as IPS) scheme (for example, disclosed in DE 40 00 451 and EP 0 588 568) and fringe field switching (FFS) scheme. There is also an electro-optic system that uses parallel electric fields. In particular, the latter of these, electro-optical schemes with good viewing angle characteristics and improved response times, are increasingly being used in LCDs for desktop monitors, even in displays for TVs and multimedia products, thus competing with TN-LCDs. have.

The liquid crystals (LC) according to the invention are preferably used in LCDs improved using cholesteric liquid crystals, also known as chiral nematic liquid crystals, which have a short spiral pitch and high dielectric anisotropy, especially for advanced products. . They are particularly useful for operating in a reflective manner, as cholesteric liquid crystals with an appropriate cholesteric pitch selectively reflect light, which can lead to coloration and avoid the use of color filters in LCDs.

The cholesteric liquid crystal may be encapsulated in the polymer matrix, for example as PDLC or NCAP.

In such products, new liquid crystal media with improved properties are needed. Thus, there is a need for a liquid crystal medium with improved behavior. Their rotational viscosity should be as low as possible. In addition to these variables, the medium should exhibit a moderately wide range of nematic phases, suitable birefringence (Δn) (preferably in the range of 0.100 to 0.300) and moderately high dielectric anisotropy (Δε). Δε should be high enough to allow a fairly low operating voltage. Preferably, it should be at least 10 to allow a driver that is easily accessible at a moderately low operating voltage. However, Δε should preferably be 40 or less, in particular 35 or less, since Δε is particularly detrimental to at least some higher specific resistance in the case of active matrix addressing. Most preferably, Δε should be in the range of 20 to 30.

The display according to the invention is preferably an active matrix LCD (abbreviated AMD) addressed by an active matrix, preferably a matrix of thin film transistors (TFTs). However, the liquid crystals according to the invention can also be advantageously used in displays with other known addressing means.

Liquid crystal compositions suitable for LCDs, in particular TN-displays, are already well known. However, the composition has significant weaknesses. Most of these result in, among other drawbacks, unfavorably long response times and / or too low contrast ratios in many products. They also most generally have insufficient reliability and stability, especially for exposure to heat, moisture, or light (particularly UV) radiation (particularly when these one or more stressors are combined with each other).

Thus, liquid crystal media having a wide range of nematic phases, suitable optical anisotropy (Δn) depending on the type of display used, high contrast ratio in the display, and particularly improved properties suitable for real products such as fast response time and good reliability Quite required.

Surprisingly, it has recently been found that liquid crystal media with suitable phase ranges, suitably high Δε and Δn, and suitably low viscosities can be realized, without exhibiting or at least significantly reducing the weaknesses of the prior art materials.

Such an improved liquid crystal medium according to the invention comprises at least the following components:

At least one compound of formula (I):

[Wherein,

R ¹ is alkyl, alkoxy, fluorinated alkyl or fluorinated alkoxy, alkenyl, alkenyloxy, alkoxyalkyl, fluorinated alkenyl or fluorinated alkenyloxy, preferably alkyl or alkoxyalkyl, most preferably n -Alkyl,

는

또는

이고,

Is

or

ego,

L ¹¹ and L ¹² are independently of each other H or F, preferably F,

X ¹ is CN or NCS, preferably CN,

i is 0 or 1, preferably 0],

At least one genetically positive compound selected from the group consisting of compounds of the formulas (II) and (III), preferably comprising at least one of each of these compounds, preferably having a dielectric anisotropy greater than 3

[Wherein,

R ² and R ³ independently of one another are alkyl, alkoxy, fluorinated alkyl or fluorinated alkoxy having 1 to 7 carbon atoms, alkenyl, alkenyloxy, alkoxyalkyl or fluorinated al having 2 to 7 carbon atoms Kenyl, preferably R ² and R ³ are alkyl or alkenyl,

내지

는 서로 독립적으로,

To

Are independent of each other,

또는

이고, 바람직하게는

or

, Preferably

또는

이고,

or

ego,

L ²¹ , L ²² , L ³¹ and L ³² are independently of each other H or F, L ²¹ and / or L ³¹ is preferably F,

X ² and X ³ independently of one another are halogen, halogenated alkyl or alkoxy having 1 to 3 carbon atoms, or halogenated alkenyl or alkenyloxy having 2 or 3 carbon atoms, preferably F, Cl, -OCF ₃ or -CF ₃ , most preferably F, Cl or -OCF ₃ ,

Z ³ is -CH ₂ CH _2- , -CF ₂ CF _2- , -COO-, trans-CH = CH-, trans-CF = CF-, -CH ₂ O- or a single bond, preferably -CH ₂ CH _2- , -COO-, trans-CH = CH- or a single bond, most preferably -COO-, trans-CH = CH- or a single bond,

l, m, n and o are each independently 0 or 1; and

At least one genetic neutral compound, optionally selected from the group consisting of compounds of the formulas IV and V, preferably comprising one or more of these respective compounds:

[Wherein,

R ⁴¹ to R ⁵² independently of one another have the meanings described for R ² in Formula II above, preferably R ⁴¹ is alkyl and R ⁴² is alkyl or alkoxy, R ⁴¹ is alkenyl and R ⁴² is alkyl , Preferably R ⁵¹ is alkyl and R ⁵² is alkyl or alkoxy, R ⁵¹ is alkenyl and R ⁵² is alkyl or alkenyl, preferably alkyl,

및

는 서로 독립적으로, 그리고

가 2회 존재하는 경우에는 이들 또한 서로 독립적으로,

And

Are independent of each other, and

Are present twice, they are also independent of each other,

이고, 바람직하게는 or

, Preferably

및

중 하나 이상은

이고,

And

One or more of

ego,

및

는 서로 독립적으로, 그리고

가 2회 존재하는 경우에는 이들 또한 서로 독립적으로,

And

Are independent of each other, and

Are present twice, they are also independent of each other,

이고, 바람직하게는 or

, Preferably

및

중 하나 이상은

또는

이고,

And

One or more of

or

ego,

Z ⁴¹ to Z ⁵² are independent of each other and, if Z ⁴¹ and / or Z ⁵¹ are present twice, they are also independent of each other: -CH ₂ CH _2- , -COO-, trans-CH = CH-, trans -CF = CF-, -CH ₂ O-, -CF ₂ O-, -C≡C- or a single bond, preferably one or more of Z ⁴¹ and Z ⁴² and one or more of Z ⁵¹ and Z ⁵² are single Is a combination,

p and q are each independently 0, 1 or 2

p is preferably 0 or 1].

The medium is a compound of formula III wherein n and o are both 1, Z ³ is preferably a single bond and all rings are 1,4-phenylene (optionally they are independently fluorinated once or twice )) And a compound of formula V wherein q is 2 and Z ⁵¹ and Z ⁵² are preferably both single bonds.

In place of or in addition to the compounds of Formulas II and / or III, the medium according to the present invention comprises at least one genetically positive compound of Formula VI:

[Wherein,

R ⁶ is alkyl, alkoxy, fluorinated alkyl or fluorinated alkoxy having 1 to 7 carbon atoms, alkenyl, alkenyloxy, alkoxyalkyl or fluorinated alkenyl having 2 to 7 carbon atoms, preferably Alkyl or alkenyl,

내지

는 서로 독립적으로,

To

Are independent of each other,

또는

이고,

or

ego,

L ⁶¹ and L ⁶² are independently of each other H or F, L ⁶¹ is F,

X ⁶ is halogen, halogenated alkyl or alkoxy having 1 to 3 carbon atoms, or halogenated alkenyl or alkenyloxy having 2 or 3 carbon atoms, preferably F, Cl, -OCF ₃ or -CF ₃ , most preferably F, Cl or -OCF ₃ ,

Z ⁶ is -CH ₂ CH _2- , -CF ₂ CF _2- , -COO-, trans-CH = CH-, trans-CF = CF- or -CH ₂ O-, preferably -CH ₂ CH _2- , -COO- or trans-CH = CH-, most preferably -COO- or -CH ₂ CH _2- ,

r is 0 or 1;

In a preferred embodiment of the invention, the liquid crystal medium according to the invention comprises at least one polymerizable compound. The polymerizable compound is a well-known non-mesogenic compound such as EHA, 2EHA, or mesogenic compound. These polymerizable mesogenic compounds are referred to herein as "reactive mesogens" (abbreviated as RMs). These polymerizable compounds may be mono- or multi-reactive, preferably bi-reactive, whether mesogenic or non-mesogenic. Preferably, the medium comprises both at least one mono-reactive compound and at least one multi-reactive, preferably di-reactive compound. Most preferably, the medium comprises one or more RMs, but additional non-mesogenic compounds may be present.

RM may be chiral or achiral and may comprise acrylate / methacrylate groups or another polymerizable group. In a particularly preferred embodiment, the RM is a chiral compound (since it is possible to simply adjust the selective reflection wavelength by polymerizing an amount of said chiral RM), so that the cholesteric pitch is no longer twisted. Increasing and consequently forming selective reflections at longer wavelengths. The resulting cholesteric pitch can be advantageously stabilized against further changes, for example by the use of a suitable filter (eg UV filter) that protects the liquid crystal from ambient radiation.

When chiral reactive mesogens are used in the liquid crystal medium according to the invention, it is also preferred to use photoinitiators in the medium in many cases where they are exposed to UV radiation. The use of photoinitiators results in a significant reduction in the required UV radiation dose.

Chiral reactive mesogens can be used in the liquid crystal medium according to the invention, since only chiral compounds are present in the medium. However, in a preferred embodiment of the invention, chiral reactive mesogens are used with conventional (non-reactive) chiral dopants. In this preferred embodiment, the preferred starting value of the cholesteric pitch, or else already somewhat closer to said preferred value, can be fixed by one or more conventional chiral dopant (s). Subsequent use of one or more chiral reactive mesogens can then further adjust the cholesteric pitch by exposing the medium to UV radiation and then depleting the chiral reactive mesogen.

In these latter embodiments, in many cases it is preferred to use conventional chiral dopants and chiral reactive mesogens having the same symbolic HTP for one another. In this embodiment, only a small total concentration is needed to achieve a short cholesteric pitch, and the overall physical properties of the mesogenic host material change only to a relatively small degree. This preferred embodiment results in a relatively low requirement for the protection of the medium against further wavelength change of selective reflection after said preferred value is achieved by UV irradiation.

However, in some cases, it is advantageous to use one or more chiral dopants and one or more chiral reactive mesogens, which conventional chiral dopants have different symbols of HTP than the chiral reactive mesogens. In this case, the central wavelength of the selective reflection can be fixed by a conventional chiral dopant. This central wavelength can then be shifted to a longer wavelength by the use of the chiral reactive mesogen. This effect can then be reversed by the exposure of the medium to UV radiation. In particular, this latter preferred embodiment results in the lowest requirement for the protection of the medium against further wavelength change of selective reflection after said preferred value is achieved by UV irradiation.

As a first approximation, it should be noted that the mixture of chiral compounds, i.e., the HTPs of conventional chiral dopants and chiral reactive mesogens approximates their respective HTP values weighed by their respective concentrations in the medium. .

RMs may be mono- or di- or multi-reactive. Particularly preferably, it is a material containing a liquid crystal having a functional group at each terminal or at least one bi-reactive compound (crosslinking agent) that is at least mesogenic, for example, may be based on diacrylate-based RM.

If the medium comprises one or more polymerizable compounds, it preferably further comprises one or more polymerization initiators such as photoinitiators and / or thermal initiators.

The liquid crystal medium according to the invention can be stabilized by the polymerization of the respective polymer precursors composed of the at least one polymerizable compound and optionally the at least one initiator, or in a preferred embodiment. Preferably, the stabilizing polymer has the form of a polymer network. That is, the non-polymerizable liquid crystal material / mesogenic material is present in a somewhat continuous form in which a rather smooth strand of polymeric material is dispersed. Polymer network stabilized liquid crystals are described, for example, in Dierking, I., Adv. Mater. 12, No. 3, pp. 167-181 (2000). In a preferred embodiment of the invention, the liquid crystal medium according to the invention comprises at least one polymerizable compound, preferably RM.

The host mixture contains a liquid crystal compound having a low molecular weight, and preferably at least one chiral dopant in an amount sufficient to cause selective reflection of the electromagnetic spectrum in the visible range. These cholesteric phases having a relatively short cholesteric pitch are preferably stabilized by a polymer. The stabilization of the (cholesteric) phase adds to the chiral liquid crystal host mixture a mixture comprising at least one polymerizable compound, preferably RM, preferably mono- and di-reactive RMs, and suitable photo-initiators, The polymerizable compound is carried out by polymerizing, for example, by exposure to UV radiation for a short time. Preferably, the polymerization is carried out in an electro-optical cell maintained at a predetermined temperature on the cholesteric phase of the chiral liquid crystal host mixture.

Said mesogenic mono-reactive compound according to the invention preferably comprises one or more ring elements linked together by means of a direct bond or via a linking group, wherein two of these ring elements are optionally identical or different from the linking group. Can be connected to each other via a coupler. The ring element is preferably selected from 4, 5, 6 or 7 membered, preferably 5 or 6 membered ring groups.

The RM used according to the invention is preferably selected from the group of compounds of the formulas VIIA and VIIB:

Where

R ⁷¹ is H, F, Cl, Br, I, CN, NO ₂ , NCS, SF ₅ , SO ₂ CF ₃ ; Or straight or branched, preferably having 1 to 20 C-atoms, unsubstituted or mono- or polysubstituted by F, Cl, Br, I or CN, optionally one or more non-contiguous CH ₂ The groups are independently of each other in each case, in such a way that no O and / or S atoms are connected directly to each other, -O-, -S-, -NH-, -NR ^01- , -SiR ⁰¹ R ^02- , -CO- , -COO-, -OCO-, -OCO-O-, -S-CO-, -CO-S-, -CY ¹ = CY ² -or -C≡C, preferably H, halogen ; N-alkyl, n-alkoxy having 1 to 7, preferably 2 to 5 C-atoms; Alkenyl, alkenyloxy or alkoxyalkyl having 2 to 7, preferably 2 to 5 C-atoms; Or CN, NCS; Halogen, preferably F, Cl; Halogenated alkyl, alkenyl or alkoxy, preferably mono-, di- or oligo-fluorinated alkyl, alkenyl or alkoxy, particularly preferably CF ₃ , OCF ₂ H or OCF ₃ ,

또는

이고,R ⁰¹ and R ⁰² are independently of each other H or alkyl having 1 to 12 C-atoms,

or

ego,

은 바람직하게는 하나 이상의 고리를 포함하는 메소젠성 잔기, 가장 바람직하게는 화학식

의 2가 라디칼이고,

Is a mesogenic moiety, preferably containing at least one ring, most preferably with formula

Is divalent radical,

은 서로 독립적으로 방향족 및/또는 지환족 고리, 또는 둘 이상의 융합된 방향족 또는 지환족 고리를 포함하는 기이며, 이때 이들 고리는 임의로 N, O 및/또는 S로부터 선택되는 하나 이상의 헤테로 원자를 함유하고 임의로 R⁷²에 의해 일치환 또는 다치환되고, To

Is a group comprising independently an aromatic and / or cycloaliphatic ring, or two or more fused aromatic or cycloaliphatic rings, wherein these rings optionally contain one or more hetero atoms selected from N, O and / or S and Optionally mono- or polysubstituted by R ⁷² ,

Z ⁷¹ to Z ⁷⁴ are independently of each other -O-, -S-, -CO-, -CO-O-, -O-CO-, -S-CO-, -CO-S-, -O-CO- ^{O-, -CO-NR 01 -,} -NR 01 -CO-, -OCH 2 -, -CH 2 O-, -SCH 2 -, -CH 2 S-, -CF 2 O-, -OCF 2 -, -CF ₂ S-, -SCF-, -CH ₂ CH _2- , -CF ₂ CH _2- , -CH ₂ CF _2- , -CF ₂ CF _2- , -CH = N-, -N = CH-, -N = N-, -CH = CR ^01- , -CY ⁰¹ = CY ^02- , -C≡C-,-(CH ₂ ) _4- , -CH = CH-CO-O-, -O-CO- CH = CH- or a single bond,

Y ⁰¹ and Y ⁰² are independently of each other F, Cl or CN, alternatively one of them may be H,

R ⁷² is H or alkyl, preferably H, or alkyl having 1 to 10 C-atoms,

PG ⁷¹ is a polymerizable group or a reactive group,

SP ⁷¹ is a spacer group or a single bond,

X ⁷¹ has one of the meanings described for Z ⁷¹ and is preferably —O—, —CO—O—, —O—CO—, —CF ₂ O—, —OCF ₂ —, —CH ₂ O— , -OCH ₂ -or a single bond;

는 상기 화학식 I에서

에 대해 기재된 의미를 갖고,

Is in the above formula (I)

Has the meaning described for,

PG ⁷² and PG ⁷³ independently of one another have one of the meanings described for PG ⁷¹ above,

SP ⁷² and SP ⁷³ independently of one another have one of the meanings described for SP ¹¹ above,

X ⁷² and X ⁷³ independently of one another have one of the meanings described for X ⁷¹ above.

In a preferred embodiment of the invention, the precursor of the polymer comprises in addition to the compound (s) of the formula VIIA preferably one or more di-reactive mesogenic monomers of the formula VIIB.

The compounds of the formulas VIIA and VIIB according to the invention may be chiral compounds.

Especially preferred are polymer precursors comprising at least one compound of formula VIIA and / or formula VIIB, wherein

Z ⁷¹ and / or Z ⁷⁴ are —O—, —CO—O—, —OCO—, —O—CO—O—, —CH ₂ —O—, —O—CH ₂ —, —CF ₂ —O -, -O-CF _2- , -C≡C-, -CH = CH- or a single bond, most preferably -CO-O-, -O-CO- or -O-;

Z ⁷¹ is not a single bond and / or;

^- the ring A ⁷¹ is a phenylene group which is optionally substituted with one or more groups R, and / or;

R ⁷¹ is alkyl or alkoxy having 1 to 12, preferably 1 to 8 C-atoms, or alkenyl, alkenyloxy or having 2 to 12, preferably 2 to 7 C-atoms or Alkynyl;

SP ⁷¹ is optionally mono- or polysubstituted by F and one or more non-adjacent CH ₂ can in each case be independently replaced with -O-, -CH = CH- or -C≡C-, 1 to 12 carbons, connected to the ring, preferably ring “A ⁷¹ ” via a group selected from —O—, —CO—O—, —O—CO—, —O—CO—O— and a single bond Alkylene with an atom and / or;

SP ⁷¹ is a single bond.

MG ⁷² to X ⁷³ are preferably the same as for MG ⁷² to X ⁷¹ .

In a preferred embodiment, rings A ⁷¹ to A ⁷³ are independently of each other an aromatic or cycloaliphatic ring, preferably a 5, 6 or 7 membered ring, or two or more, preferably 2 or 3 fused aromatic or cycloaliphatic rings is a group containing, where these rings are optionally N, O and / or contain one or more heteroatoms selected from S, and optionally is monosubstituted or polysubstituted by L ^7, L ⁷ is F, Cl, Br, CN , OH, NO ₂ , and / or an alkyl, alkoxy, alkylcarbonyl or alkoxycarbonyl group having 1 to 12 C atoms, wherein one or more H atoms are optionally substituted with F or Cl.

L ⁷ is preferably F, Cl, CN, OH, NO ₂ , CH ₃ , C ₂ H ₅ , OCH ₃ , OC ₂ H ₅ , COCH ₃ , COC ₂ H ₅ , COOCH ₃ , COOC ₂ H ₅ , CF ₃ , OCF ₃ , OCHF ₂ or OC ₂ F ₅ , in particular F, Cl, CN, CH ₃ , C ₂ H ₅ , OCH ₃ , COCH ₃ or OCF ₃ , most preferably F, Cl, CH ₃ , OCH ₃ Or COCH ₃ .

Preferred rings A ⁷¹ to A ⁷³ are, for example, furan, pyrrole, thiophene, oxazole, thiazole, thiadiazole, imidazole, phenylene, cyclohexylene, cyclohexenylene, pyridine, pyrimidine, pyrazine, a Zulene, indyin, naphthalene, tetrahydronaphthalene, decahydronaphthalene, tetrahydropyran, anthracene, phenanthrene and fluorene.

Particularly preferably, at least one of these rings A ⁷¹ to A ⁷³ is furan-2,5-diyl, thiophen-2, in which one or two non-adjacent CH ₂ groups are optionally replaced with O and / or S, 5-diyl, thienothiophene-2,5-diyl, dithienothiophene-2,6-diyl, pyrrole-2,5-diyl, 1,4-phenylene, azulene-2,6 -Diyl, pyridine-2,5-diyl, pyrimidine-2,5-diyl, naphthalene-2,6-diyl, 1,2,3,4-tetrahydro-naphthalene-2,6-di Mono, indene-2,5-diyl or 1,4-cyclohexylene, wherein these groups are unsubstituted or mono- or polysubstituted with L as defined above.

내지

는 서로 독립적으로

또는 이들의 거울상이며, 상기 식에서Preferably,

To

Independently of each other

Or mirror images thereof, wherein

R is alkyl having 1 to 12, preferably 1 to 7 C-atoms, or alkenyl or alkynyl having 2 to 12, preferably 2 to 7 C-atoms, both of which One or more non-adjacent -CH ₂ -groups not adjacent to the phenyl ring can be replaced with -O- and / or -CH = CH- and / or one or more H-atoms can be replaced by halogen, preferably F And / or;

는

또는

이다.Preferably,

Is

or

to be.

는 단지 단일환상 고리 A⁷¹ 내지 A⁷³만을 함유한다. 매우 바람직하게는, 이는 1 또는 2개의 5 및/또는 6원 고리를 갖는 기이다.In a preferred embodiment of the invention,

Contains only monocyclic rings A ⁷¹ to A ⁷³ . Very preferably it is a group having one or two five and / or six membered rings.

Preferred sub formulas of this group are listed below. For simplicity, in these groups Phe is 1,4-phenylene, PheL is a 1,4-phenylene group substituted with 1 to 4 L groups as defined above and Cyc is 1,4-cyclohexylene Pyd is pyridine-2,5-diyl and Pyr is pyrimidine-2,5-diyl. The following list of preferred groups includes sub-formulas VII-1 to VII-20 and their mirror images:

In these preferred groups, Z has the meaning of Z ⁷¹ described in formula VIIA. Preferably, Z is -COO-, -OCO-, -CH ₂ CH _2- , -C≡C- or a single bond.

는 하기 화학식 VIIa 내지 VIIj 및 이들의 거울상으로부터 선택된다:Very preferably,

Is selected from formulas VIIa to VIIj and mirror images thereof:

Where

L is F, Cl, Br, CN, OH, NO ₂ and / or an alkyl, alkoxy, alkylcarbonyl or alkoxycarbonyl group having from 1 to 12 C atoms, wherein one or more H atoms are optionally F or Cl Will be replaced,

r is 0, 1, 2, 3 or 4, preferably 0, 1 or 2.

는 매우 바람직하게는

또는

, 뿐만 아니라

이며, 이때 L은 각각 독립적으로 상기 기재된 의미들 중 하나를 갖는다.In these preferred formulas

Very preferably

or

, As well as

Wherein L each independently has one of the meanings described above.

를 하나 이상 포함한다.Particularly preferred compounds of formula I are those in which r is 1 or 2

It includes one or more.

를 둘 이상 및/또는 r이 2인 기

를 하나 이상 포함한다.More preferred compounds of formula (I) are those in which r is 1

Two or more groups and / or r is 2

It includes one or more.

는 매우 바람직하게는 하기 화합물들이다:

Are very preferably the following compounds:

Where

The 1,4-phenylene ring may be optionally substituted by R, preferably alkyl, preferably methyl, and / or alkoxy, and / or halogen, preferably F.

More preferably,

는 하기 화합물들 또는 이들의 거울상이다:

Is the following compounds or their mirror image:

Where

R has the meaning described above, and preferably at least one non-adjacent -CH ₂ -group can be optionally replaced by -O- and / or -CH = CH- and / or at least one H atom is halogen, preferably Alkyl having 1 to 6 C-atoms which may be replaced by F, preferably n-alkyl.

In a preferred embodiment of the invention, the liquid crystal medium according to the invention is a compound of sub-formulas I-1 to I-5, preferably a compound of sub-formulas I-2, I-4 and I-5, most preferred Preferably at least one compound of formula (I) selected from compounds of sub-formula (I-2):

Where

R ¹ has each meaning described for Formula 1 above, preferably alkyl, most preferably n-alkyl, and X ¹ is preferably CN.

In a preferred embodiment of the invention, the liquid crystal medium according to the invention comprises at least one compound selected from the group of compounds of formulas II-1 and II-2, preferably at least one compound of formula II-2:

Where

The variable has each meaning described for Formula II above and X2 is preferably F or -OCF ₃ .

Preferably, the medium is selected from the group of compounds of formulas II-1 and II-2, wherein L ²¹ and L ²² comprise at least one compound that is both F.

Preferably, the medium comprises at least one compound of formula (II-1), preferably a compound selected from fluorides of formulas (II-1a to II-1c), preferably a compound of formula (II-1c):

Where

The variables have the respective meanings described above, preferably L ²¹ to L ²² are all H, or L ²¹ , L ²² , L ²³ and L ²⁴ are all F.

In a preferred embodiment, the medium comprises at least one compound of formula II-1c wherein L ²¹ , L ²² , L ²³ and L ²⁴ are all F.

Preferably, the compound comprises at least one compound selected from the group of compounds of formulas II-2a to II-2c, preferably at least one compound of formula II-2c:

Where

The variables have the respective meanings described above, L ²³ to L ²⁷ are independently of each other and other variables H or F, L ²¹ and L ²² are preferably both F, two or three of L ²³ to L ²⁷ , Most preferably L ²³ to L ²⁵ is F, others of L ²¹ to L ²⁷ are H or F, preferably H, and X ² is preferably F or -OCF ₃ , most preferably F .

Particularly preferred compounds of formula II-2 are compounds of formula II-2c-1:

Wherein R ² has the meaning described above.

In another preferred embodiment of the invention, the medium comprises at least one compound selected from the group of compounds of formulas III-1 and III-2:

Wherein the variables have the respective meanings described for Formula III above.

The medium is preferably a compound of formula III-1, preferably a compound selected from the group of compounds of formulas III-1a to III-1f, preferably of compounds of formulas III-1a, III-1c and III-1d At least one compound selected from the group consisting of compounds, most preferably each of Formulas III-1a and / or III-1c and / or III-1d:

Wherein the variables have the respective meanings described above, L ³³ to L ³⁷ are independently of each other and other variables are H or F, L ³¹ and L ³² are preferably both F, and L ³³ to L ³⁷ Two or three, most preferably L ³³ to L ³⁵ is F, others of L ³¹ to L ³⁷ are H or F, preferably H and X ³ is preferably F or —OCF ₃ .

Most preferred compounds of formula III-1 are selected from the group consisting of compounds of formulas III-1a-1, III-1c and III-1d-1:

In the formula, R ³ has the meaning described above.

The compound of formula I is preferably selected from the group consisting of compounds of formulas IV-1 to IV-7, more preferably compounds of formulas IV-6 and / or IV-7:

Where

R ⁴¹ and R ⁴² have the respective meanings described in formula IV above, in particular in formulas IV-1 and IV-5, R ⁴¹ is preferably alkyl or alkenyl, preferably alkenyl and R ⁴² is preferred Preferably alkyl or alkenyl, preferably alkyl, alternatively in formula IV-2, R ⁴¹ and R ⁴² are preferably alkyl, and in formula IV-4 R ⁴¹ is preferably alkyl or alkenyl, preferably Preferably alkyl and R ⁴² is preferably alkyl or alkoxy, preferably alkoxy.

Preferably the medium comprises at least one compound selected from the group consisting of compounds of Formulas IV-6 and IV-7; Most preferably at least one compound of each of Formulas IV-6 and IV-7.

Preferred compounds of formula IV-6 are compounds of formulas CPTP-n-m and CPTP-n-Om, more preferably compounds of CPTP-n-Om, and preferred compounds of formula IV-7 are compounds of formula CPGP-n-m. Definitions of these abbreviations (acronyms) are set forth in Tables A to C and illustrated in Table D below.

In a preferred embodiment, the liquid crystal medium according to the invention comprises at least one compound of formula V selected from the group consisting of compounds of formulas V-1 to V-6:

Where

R ⁵¹ and R ⁵² have each meaning described in formula V above, R ⁵¹ is preferably alkyl, more preferably n-alkyl, and R ⁵² in formula V-1 is preferably alkenyl, preferably Is 3-alkenyl, most preferably — (CH ₂ ) ₂ —CH═CH—CH ₃ , and R ⁵² in formula V-3 is preferably alkyl or alkenyl, preferably n-alkyl or ³ -alkenyl, most preferably — (CH ₂ ) ₂ —CH═CH—CH ₃ , R ⁵² in formula V-3 is preferably alkyl, and “F _0/1 ” in formula V-4 Is preferably F.

Preferred compounds of formula V-1 are compounds of formulas PP-n-2V and PP-n-2Vm, more preferably compounds of formula PP-1-2V1. Preferred compounds of formula V-2 are compounds of formula PTP-n-Om, particularly preferably PTP-1-O2, PTP-2-O1 and PTP-3-O1. Preferred compounds of the formula (V-3) are compounds of the formulas PGP-nm, PGP-n-2V and PGP-n-2Vm, more preferably of formulas PGP-2-m, PGP-3-m and PGP-n-2V Compound. Preferred compounds of formula V-4 are compounds of formula PPTUI-n-m, particularly preferably compounds of PPTUI-3-2, PPTUI-3-3, PPTUI-3-4 and PPTUI-4-4. Preferred compounds of formula V-5 are compounds of formula PGGIP-n-m. Preferred compounds of formula (V-6) are compounds of formula (PGIGP-n-m). Definitions of these abbreviations (acronyms) are described in Tables A-C and illustrated in Table D below.

The compound of formula VI is preferably a compound selected from the group consisting of compounds of formulas VI-1 and VI-2, preferably a compound of formula VI-1:

Where

The variables have the respective meanings described above, and the variables L ⁵³ and L ⁶⁴ are H or F independently of each other and other variables, preferably Z ⁶ is -CH ₂ -CH _2- , preferably X ⁶ Is F.

Preferably, the liquid crystal medium according to the invention comprises, or more preferably, a compound selected from the group consisting of compounds of formulas I to VI and VIIa and VIIb, more preferably compounds of formulas I to V and VIIa and / or VIIb. Preferably consists mainly of these compounds, more preferably consists essentially of these compounds, or most preferably consists entirely of these compounds.

As used herein, “comprising” with reference to a composition, unless otherwise explicitly defined, involves an individual, such as a medium or a component, preferably comprising at least 10%, more and most preferably at least 10% of the total concentration of the component or components or compounds or compounds described. Preferably it means containing 20% or more.

As used herein, "consisting mainly of" means that the subject concerned is at least 55%, preferably at least 60%, more and most preferably at least 70% of the component or components or compounds or compounds described. It means to contain.

As used herein, "consisting essentially of" means that, unless otherwise explicitly defined, the subject concerned is at least 80%, preferably at least 90%, more and most preferably 95% of the components or components or compounds or compounds described. It means containing more.

As used herein, "consisting entirely of" means that the subject concerned contains at least 98%, preferably at least 99%, more and most preferably 100.0% of the described component or components or compound or compounds, unless explicitly defined otherwise. I mean.

In addition, other mesogenic compounds not explicitly mentioned above may optionally and advantageously be used in the medium according to the invention. Such compounds are known to those skilled in the art.

The liquid crystal medium according to the invention has a clearing point of at least 85 ° C, preferably at least 90 ° C.

The Δn at 589 nm (Na ^D ) and 20 ° C. of the liquid crystal medium according to the present invention is preferably in the range of 0.150 or more and 0.350 or less, more preferably in the range of 0.170 or more and 0.250 or less, more preferably 0.180 or more and 0.220 or less Range.

Δε at 1 kPa and 20 ° C of the liquid crystal medium according to the invention is preferably at least 10, preferably at least 15, more preferably at least 20, most preferably at least 25, preferably at most 40, more Preferably it is 35 or less, More preferably, it is 10 or more and 40 or less, Most preferably, it is 20-30.

The nematic phase of the medium according to the invention without chiral dopant is preferably at least 0 ° C. or lower and 80 ° C. or higher, more preferably at least −20 ° C. or lower and 85 ° C. or higher, most preferably at least −20 ° C. or lower and 90 ° C. or higher. Especially at least -30 ° C or less and 95 ° C or more.

The liquid crystal medium is preferably characterized for comparison purposes in TN displays operating at a second transition minimum according to Gooch and Tarry with an optical retardation (d · Δn) in the range from 1.0 μm to 1.1 μm. . However, they are preferably used as cholesteric liquid crystals, also called chiral nematic liquid crystals having a rather short cholesteric pitch, and preferably their cholesteric pitch is such that their selective reflection wavelength is in the visible range of the electromagnetic spectrum. Ie selected to be within 400 to 800 nm.

The liquid crystal medium is preferably a spiral tween in the range of at least 20 μm ⁻¹ , preferably at least 40 μm ⁻¹ , more preferably at least 60 μm ⁻¹ , most preferably at least 80 μm ⁻¹ and up to 260 μm ^−1. It contains one or more chiral dopants with an absolute value of helical twisting power (HTP).

The liquid crystal medium is preferably 50 to 100% in total, more preferably 70 to 100%, more preferably 80 to 100%, in particular 90 to 100% of the formulas I, II, III, IV, V and VI Compounds, preferably compounds of formula (I), (II), (III), (IV) and (V).

The liquid crystal medium more preferably comprises, or more preferably consists mainly of, compounds of formulas I, II, III, IV, V and VI, preferably compounds of formulas I, II, III, IV and V. Or more preferably consist essentially of them, or most preferably consist entirely of them.

The compound of formula (I) is preferably used in the medium at a total concentration of 1 to 35%, more preferably 2 to 30%, even more preferably 3 to 20% and most preferably 5 to 15% of the total mixture. do.

The compounds of the formulas (II) and (III) are used together in the medium at a total concentration of 40 to 80%, more preferably 45 to 75%, even more preferably 50 to 70%, most preferably 55 to 65% of the total mixture. do.

The compound of formula (II) is preferably used in the medium at a total concentration of 15 to 35%, more preferably 20 to 30% and most preferably 22 to 28% of the total mixture.

The compound of formula III is preferably used in the medium at a total concentration of 20 to 45%, more preferably 25 to 40% and most preferably 30 to 35% of the total mixture.

The compound of formula IV is preferably used in the medium at a total concentration of 10 to 35%, more preferably 15 to 30% and most preferably 20 to 25% of the total mixture.

The compound of formula (V) is preferably used in the medium at a total concentration of 10 to 30%, more preferably 12 to 28% and most preferably 16 to 23% of the total mixture.

The compound of formula VI is preferably used in the medium at a total concentration of 0 to 30%, more preferably 0 to 15% and most preferably 1 to 10% of the total mixture.

The polymerizable compound, preferably a compound of the formula VIIA and / or VIIB, is preferably medium at a total concentration of 0 to 10%, more preferably 0 to 7% and most preferably 0.5 to 5% of the total mixture. Used during

Preferably at least one polymerization initiator is used, preferably at least one photo initiator. The concentration of the initiator is from 0.1 to 10%, more preferably from 0.2 to 5% and most preferably from 0.5 to 2% of the total concentration of the polymerizable compounds.

Preferably the media according to the invention further comprise one or more chiral compounds as chiral dopants to adjust their cholesteric pitch. Their total concentration in the media according to the invention is preferably in the range from 0.1 to 15%, more preferably from 1 to 10% and most preferably from 2 to 6%.

Optionally, the medium according to the invention may comprise further liquid crystal compounds in order to adjust the physical properties. Such compounds are known to those skilled in the art. Their concentration in the medium according to the invention is preferably from 0 to 30%, more preferably from 0.1 to 20% and most preferably from 1 to 15%.

The medium according to the invention preferably comprises at least one compound of the formula

Formula I-2; And / or

Formula II-1c, preferably formula PUQU-n-F; And / or

Formula II-2c, preferably formula II-2c-1; And / or

Formula III-1a, preferably formula III-1a-1; And / or

Formula III-1a, preferably formula III-1a-1; And / or

Formula III-1c, preferably formula III-1c-1; And / or

Formula III-1d, preferably formula III-1d-1; And / or

Formula IV-6, preferably formula CPTP-n-Om and / or CPTP-n-m; And / or

Formula IV-7, preferably formula CPGP-n-Om and / or CPGP-n-m; And / or

Formula V-1, preferably formula PP-n-mV and / or PP-n-mVI; And / or

Formula V-2, preferably formula PTP-n-Om; And / or

Formula V-3, preferably formula PGP-n-m and / or PGP-n-mV; And / or

Formula V-4, preferably formula PPTUI-n-m; And / or

Formula R-5011 or S-5011; And / or

At least one reactive polymerizable compound; And / or

At least one polymerization initiator.

As used herein, the term "dielectrically positive" is used for a compound or component with a Δε greater than 3.0, and the expression "dielectrically neutral" means a compound with a Δε of -1.5 or more and 3.0 or less. Used for a component, the expression "dielectrically negative" is used for a compound or component having a Δε less than -1.5. Δε is determined at 1 kHz frequency and 20 ° C. The dielectric anisotropy of each compound is determined from the result of a 10% solution of each individual compound in the nematic host mixture. If the solubility of each compound in the host mixture is less than 10%, the concentration is reduced by a factor of 2 until the resulting mixture is at least stable enough to determine its properties. However, preferably the concentration is maintained at least 5% to keep the significance of the result as high as possible. The capacity of the test mixture is determined in both cells with homeotropic orientation and cells with homogeneous orientation. In both types of cells, the cell gap is about 20 μm. The applied voltage is a rectangular wave with a frequency of 1 Hz and is typically a root mean square (rms) of 0.5 to 1.0 V, but this is always chosen to be below the threshold of this capacity of each test mixture.

Δε is defined as (ε _∥ −ε _⊥ ), and ε _av is defined as (ε _∥ + 2ε _⊥ ) / 3. The mixture ZLI-4792 is used as the host mixture for the genetically positive compounds, as well as for the genetic neutral compounds as well as for the genetic negative compounds, all of which are from Merck KGaA, Germany. . The permittivity of the compound is determined from the change in each value of the host mixture when the compound of interest is added. This value is extrapolated to 100% concentration of the compound of interest.

The component with the nematic phase at the measurement temperature of 20 ° C. is measured by itself and the rest are treated like the compound.

Unless expressly stated otherwise, the term "threshold voltage" herein refers to the optical threshold and is presented in 10% relative contrast (V ₁₀ ), and the term "saturation voltage" refers to optical saturation and 90% relative It is described as contrast (V ₉₀ ). In addition, the capacitive threshold voltage V ₀ , also referred to as Freedericks-threshold V _Fr , is used only when explicitly stated.

Unless expressly stated to the contrary, the scope of the variables described herein all include limits.

Unless explicitly stated otherwise, throughout this application all concentrations are given in weight percent and for each total mixture, all temperatures are given in degrees Celsius and all temperature differences are stated in degrees Celsius. All physical properties are described in "Merck Liquid Crystals, Physical Properties of Liquid Crystals", Status Nov. 1997, Merck KGaA, Germany, and is described for a temperature of 20 ° C. unless explicitly stated otherwise. Optical anisotropy (Δn) is determined at a wavelength of 589.3 nm. The dielectric anisotropy (Δε) is determined at 1 kHz frequency. Threshold voltage as well as all other electro-optic properties were measured using a test cell manufactured by Merck Kagaea, Germany. The test cell for measuring Δε has a cell gap of about 20 μm. The electrode was a circular ITO electrode with a 1.13 cm 2 area and guard ring. The alignment layer was lecithin for the vertical orientation (ε _⊥ ) and polyimide AL-1054 from Synthetic Rubber of Japan for the horizontal orientation (ε _∥ ). The capacity was determined with a Solatron 1260 frequency response analyzer using a sine wave with a 0.3 V _rms voltage. The test cell used had a cell gap selected to have an optical delay suitable for less than or equal to the first transmission minimum according to the molar and terry, and typically was about 0.45 μm ⁻¹ . The light used for electrooptical measurements was white light. The instrument used here is commercially available from Autronic-Melchers, Karlsruhe, Germany. The characteristic voltage was determined under vertical observation. Threshold voltage (V ₁₀ ), mid-grey voltage (V ₅₀ ) and saturation voltage (V ₉₀ ) were determined for 10%, 50% and 90% relative contrast, respectively.

The response time is again from the increase time τ _on , 100% for the change time τ ₉₀ −τ ₀ (ie, including the delay time τ ₁₀ −τ ₀ ) of the relative contrast of 0 to 90%, respectively. It is described as the decay time τ _off for the change time of the relative contrast to 10%, and the total response time τ _total = tau _on + tau _off .

The liquid crystal medium according to the invention may comprise further additives in conventional concentrations. The total concentration of these additional components ranges from 0 to 10%, preferably 0.1 to 6%, based on the total mixture. The concentrations of the individual compounds used are each preferably in the range of 0.1 to 3%. When referring to concentration values and ranges of liquid crystal components and compounds of the liquid crystal medium herein, the concentrations of these components and similar additives are not taken into account. It is also effective as the concentration of the dichroic dye used in the mixture which is not calculated when the concentration of compounds and components of the host mixture is not specified. The concentration of each additive above is always described for the final doped mixture.

The liquid crystal medium according to the invention consists of several compounds, preferably 3 to 30, more preferably 4 to 20 and most preferably 4 to 16 compounds. These compounds are mixed in a conventional manner. In general, compounds used in smaller amounts are dissolved in compounds used in excess. It is particularly easy to observe that the dissolution process is complete when the temperature is higher than the clearing point of the compound used at higher concentrations. However, other conventional methods, such as so-called pre-mixtures, which can be homogeneous or eutectic mixtures of compounds, or so-called multi-container systems, which are mixtures in which the components themselves can be used directly. -bottle-systems may also be used to prepare the medium.

The liquid crystal medium according to the invention, preferably comprising at least one chiral dopant, selectively reflects radiation in the visible range of the electromagnetic spectrum, ie in the range from 400 to 800 nm. Preferably, the bands of their selective reflections extend within the range of said wavelengths, more preferably the center wavelength of these reflecting bands lies within said range, and most preferably their fully reflected bands are within said range. Lies within. Preferably they have a selective reflection of half width (1/2 FWHM) in the range of 15 to 60 nm, preferably 20 to 55 nm and most preferably 25 to 50 nm. In particular, the relative half width, ie, the ratio of the half width of the reflection band to the center wavelength, is preferably 1 to 20%, more preferably 2 to 16%, more preferably 4 to 10%, most preferably 6 to 6 8% range.

The center wavelength of the selective reflection produced at the temperatures described can be calculated from the actual center of the chiral dopant in the host used through estimation of the polynomial series (I).

Where

α, β and γ are material constants specific to the combination of a given chiral dopant in a given host mixture.

c (dopant) is the concentration of chiral dopant in the host mixture.

In many practical cases, even considering only the first term, the primary term "[alpha] [c (dopant)] ^-1 ") provides sufficiently accurate results. The variable "α" is similar to the inverse of HTP (ie, HTP ^-1 ). Here, in the determination of the selective reflection wavelength of the cholesteric LC, similar to the "Bragg" reflection, the effective refractive index of the mixture should be further considered for more accurate numerical calculations.

Typically, the variables α, β and γ depend more strongly on the type of chiral dopant than the particular liquid crystal mixture used.

Clearly, they depend on the enantiomeric excess of each chiral dopant. They have their respective maximum absolute values for pure enantiomers and zero for racemates. Herein, these described values are for pure enantiomers having enantiomeric excess of at least 98%.

Preferably, the absolute value of the variable α of each chiral dopant in each liquid crystal medium according to the invention is in the range of 5 to 25 nm, more preferably 10 to 20 nm and most preferably 12 to 16 nm.

These media may comprise one or more chiral dopants. If they comprise two or more chiral dopants, they may be advantageously selected in one of the known ways of compensating for the temperature dependence of the cholesteric pitch and thus the selective reflection wavelength, for example. Here, in one host mixture the chiral dopant having the variable of the opposite sign as well as the chiral dopant having the variable α of the same symbol, according to the properties of the variable of the higher order term of the equation (I), in particular the variable β of the secondary term Can be used.

More preferably, as an embodiment of the invention using a single chiral dopant, it shows that it has a low temperature dependence, ie small variable β of chiral pitch derived in each host mixture. By adding suitable additives, the liquid crystal medium according to the invention uses liquid crystal media such as TN, TN-AMD, ECB-AMD, VAN-AMD, IPS and OCB LCD, or PDLC, NCAP, PN LCD, especially ASM- It can be modified to be used in all known types of liquid crystal displays using complex systems such as PA LCDs.

Melting point T (C, N), transition T (S, N) from smectic phase (S) to nematic phase (N), and clear point T (N, I) of the liquid crystal are described in degrees Celsius.

In this application, and in particular in the examples below, the structure of the liquid crystal compound is represented by an abbreviation, which is also referred to as “acronym”. The modification of the abbreviation to its corresponding formula is simplified according to the following three tables A to C.

All of the C _n H _{2n +1} , C _m H _{2m +1} and C _l H _{2l +1} groups are straight chain alkyl groups having n, m and l carbon atoms, respectively, and C _n H _2n , C _m H _2m and C _{All of the 1} H _2l groups are each preferably (CH ₂ ) _n , (CH ₂ ) _m and (CH ₂ ) _1, and —CH═CH— is preferably trans—each E vinylene.

Table A lists the codes used for the ring elements, Table B lists the codes for the linking groups, and Table C lists the codes for the left and right end groups of the molecule.

Table D lists together the exemplary structures of the molecules and their respective codes.

Table A: Ring Elements

Table B: Connectors

Table C: End groups

In the above, n and m are each an integer and "..." represents a space apart from other abbreviations in the table.

The liquid crystal medium according to the invention preferably comprises at least one compound selected from the group consisting of the compounds of the formulas in the following table, in addition to the compounds of the formula (I).

Table D

Table E below lists the chiral dopants preferably used in the liquid crystal medium according to the invention.

Table E

In a preferred embodiment of the invention, the medium according to the invention comprises at least one compound selected from the group consisting of the compounds of Table E.

Table F below lists the stabilizers preferably used in the liquid crystal medium according to the invention.

TABLE F

In the above table, "n" means an integer of 1 to 12.

In a preferred embodiment of the invention, the medium according to the invention comprises at least one compound selected from the group consisting of the compounds of Table F.

The liquid crystal medium according to the invention preferably comprises at least 4, preferably at least 6 compounds selected from the group consisting of the compounds of Table D, preferably selected from the group consisting of the compounds of Table D. Compounds having at least 7, preferably at least 8, preferably at least 3 different formulas.

1 shows UV reflection peaks of cholesteric liquid crystal mixtures A-1 and A-2 according to an embodiment of the present invention.
2 shows the UV reflection peaks of the cholesteric liquid crystal mixtures B-1 and B-3 according to the embodiment of the present invention.

Example

The examples provided below illustrate the invention without limiting it in any way.

However, physical properties and compositions show to those skilled in the art what properties can be obtained and their ranges can be modified. In particular, the combination of various properties that can be obtained preferably is well defined for those skilled in the art.

Example  One

Example  1.1 and 1.2

Each of A with a relatively short cholesteric pitch was added by adding 3.2% or 2.3% of the chiral dopant R-5011 from Merk Kagaea, Darmstadt, Germany to 96.8% and 97.7% of the mixtures AO from Example 1, respectively. Each cholesteric mixture called -1 and A-2 was prepared. The transition temperature from the cholesteric liquid crystal phase to the isotropic phase (ie, clear point) was 83.5 ° C. for mixture A-1 with 3.2% R-5011 and 86.5 ° C. for mixture with 2.3% R-5011, respectively. .

Mixture A-1 exhibits reflection in the blue spectral range from 377 to 435 nm (FWHM) as shown in FIG. 1, and mixture A-2 is also selective in the green spectral range from 506 to 578 nm with reference to FIG. 1. Has reflection. Commas on the "R" -axis in the figure represent decimal points.

Example  1.3

Similar to Example 1.1, cholesteric mixture A-3 was prepared by adding 1.6% of chiral dopant R-5011 to 98.4% of mixture A-0 from Example 1. This mixture had selective reflection in the red visible spectral region.

In the same way, each chiral dopant concentration can be used to easily implement a mixture that reflects in any desired spectral region.

The results of all the examples are listed in Table 2 below. The variable "α" was also calculated for each individual example. And, as expected, it was almost constant for the combination of chiral dopant R-5011 and host mixture A-0, and (12.7 ± 0.3) for the concentration used herein.

Example  2

Example  2.1 to 2.4

Example  2.1

3.2% of chiral dopant R-5011 was added to 96.8% of mixture B-O from Example 2 to prepare each cholesteric mixture B-1 having a relatively short cholesteric pitch. The transition temperature (ie, clear point) of the mixture B-1 from the cholesteric liquid crystal phase to the isotropic phase was 74.5 ° C. Mixture B-1 showed reflection in the blue spectral range from 418 to 488 nm (FWHM).

Example  2.2

Each cholesteric mixture B-2 with a shorter cholesteric pitch longer than the mixture B-1 of Example 2.1, with 2.6% chiral dopant R-5011 added to the mixture BO 97.4% from Example 2 Was prepared. The clear point of the mixture B-2 was 76.5 degreeC. Mixture B-2 showed reflection in the green spectral range from 512 to 590 nm (FWHM). The central wavelength of selective reflection was 551 nm.

Example  2.3

2.2% of chiral dopant R-5011 was added to the mixture BO 97.8% from Example 2, so that each cholesteric mixture B-3 having a cholesteric pitch much longer than the mixture B-2 of Example 2.2 was added. Prepared. The clearing point of the mixture B-3 was 77.5 ° C. Mixture B-3 showed reflection in the red spectral range from 600 to 693 nm (FWHM).

The production spectra of the selective reflections for the mixtures B-1 and B-3 of Examples 2.1 and 2.3 are all shown in FIG. 2. Commas on the figure "R" -axis represent decimal points. In this figure, the results for mixture B-2 of Example 2.2 are not included to avoid any confusion by overlapping spectra. The band of selective reflection of mixture B-2 almost completely fills the gap in the visible spectrum between the two mixtures B-1 and B-2.

Example  2.4

2.7% of chiral dopant R-5011 was added to 97.3% of the mixture BO from Example 2, so that each cholesteric mixture B-4 having a cholesteric pitch somewhat shorter than the mixture B-2 of Example 2.2 was added. Prepared. The clear point of the mixture B-4 was 76.0 degreeC. Mixture B-4 showed reflection in the green spectral range. The central wavelength of selective reflection was about 530 nm.

The results for mixtures B-2 and B-4 have a selective reflection width with a slightly smaller bandwidth than mixture B-2 and a nearly identical center wavelength at the center between the two mixtures B-2 and B-4. Comparable to that for mixture A-2 from Example 1.2 having.

Example  2.5

Each cholesteric mixture B- having a shorter cholesteric pitch slightly longer than the mixture B-2 of Example 2.2, by adding 2.43% of chiral dopant R-5011 to the mixture BO 97.57% from Example 2 5 was prepared. The clearing point of the mixture B-5 was 77.0 ° C. Mixture B-5 showed reflection in the yellow spectral range. The central wavelength of selective reflection was about 584 nm and ranged from 541 to 626 nm (FWHM).

Example  2.6

Each cholesteric mixture B- having a shorter cholesteric pitch slightly longer than the mixture B-3 of Example 2.3 by adding 2.13% of chiral dopant R-5011 to the mixture BO 97.87% from Example 2 6 was prepared. The clear point of the mixture B-6 was 78 degreeC. Mixture B-6 showed reflection in the red spectral range. The central wavelength of selective reflection was about 670 nm and ranged from 619 to 720 nm (FWHM).

The variable “α” for the combination of chiral dopant R-5011 and host mixture B-0 was (14.3 ± 0.2) for the concentrations used herein.

Example  3

In this example, mixture B-2 of Example 2.2, consisting of 2.6% of R-5011 and 97.4% of mixture B-0 and having reflection in the green spectral range, is used as starting mixture, which is then formed from the material Stabilize. To this end, in mixture B-2, RM1 (bis-methacrylate), a di-reactive mesogen of the formula:

Photoinitiator Irgacure (registered trademark) 651 (IRG-651 (registered trademark)) (available from Ciba, Switzerland):

Add with.

The concentration of RM used is 1% and the concentration of photoinitiator is set to 1% of the RM concentration.

The mixture is homogenized by heating once to 60 ° C. on a hot plate for 20 minutes (series A) and investigated for its properties. It is then heated on the second hot plate to the same temperature for 20 minutes (series B) and irradiated again. The mixture (B2M-1) is investigated as described above. It is further filled into the test cell and then polymerized by exposing the reactive mesogen to UV radiation.

Example  4

Example  4.1 to 4.3

Similar to Example 3, the mixture B-2 of Example 2.2 is stabilized with a polymer formed in the material. The concentration of RMs again varies from 1% to 3% to 5% of the mixture and the concentration of photoinitiator is set in each case to 1% of RM. However, different RMs, di-reactive mesogens, RM 2 (bis-acrylates) of the formula

These mixtures (B2M2-1 to B2M2-3) are heated on a hot plate to a temperature of 60 ° C. for 20 minutes to homogenize them and investigated as described above. They are further filled into test cells, and then the reactive mesogens are polymerized by exposure to UV radiation.

Example  5

Example  5.1 to 5.3

Similar to Examples 3 and 4, the basic mixture is stabilized with a polymer formed in the material. The concentration of RMs again varies from 1% to 3% to 5% of the mixture and the concentration of photoinitiator is set in each case to 1% of RM. Here, similar to Example 4, RM2, which is a bi-reactive mesogen, is used.

However, mixture B-6 of Example 2.6 is used here.

Each of these mixtures (B6M2-1 to B6M2-3) is heated on a hot plate to a temperature of 60 ° C. for 20 minutes to homogenize them and investigated as described above. They are further filled into test cells, and then the reactive mesogens are polymerized by exposure to UV radiation.

Example  6

A cholesteric mixture C-1 with a short cholesteric pitch was prepared by adding 2.8% chiral dopant R-5011 to the mixture C-0 97.2%. The clear point of the mixture C-1 was 84.0 degreeC. Mixture C-1 showed reflection in the green spectral range. The central wavelength of selective reflection was about 526 nm. The band of selective reflection is in the range of 484 to 567 nm (FWHM), thus Δλ / 2 is 42 nm.

Example  7

Example  7.1 to 7.4

Alternatively, 2.7, 3.1 3.2 and 3.3% of chiral dopant R-5011, respectively, were added to each amount of the mixture DO to prepare cholesteric mixtures D-1 to D-4, all with relatively short cholesteric pitches. It was. The clear points of these mixtures were 78.5, 77.0, 77.0 and 76.5 ° C, respectively. Mixture D-4 showed reflection in the green spectral range, and all three mixtures D-1 through D-3 showed reflection in the blue spectral range. The change in the center of the chiral dopant in these three mixtures makes it possible to select an appropriate blue color. The central wavelength of selective reflection of mixture D-4 is about 536 nm, the following mixtures continuously move towards shorter wavelengths, and the concentration of chiral dopant increases.

Example  8

Example  8.1 to 8.3

3.28%, 2.82% or 2.27% of Chiral Dopant R-5011 from Merk Kagaea, Darmstadt, Germany was added to the mixtures EO 96.72%, 97.18% and 97.73% from Example 8, respectively, all of which were relatively short cholesters. Each cholesteric mixture, called E-1 to E-3, with a rig pitch was prepared. The transition temperature from the cholesteric liquid crystal phase to the isotropic phase (ie, the clear point) is 73.5 ° C. for mixture E-1 with 3.28% R-5011, respectively, and of mixture E-2 with 2.82% R-5011. 75.0 ° C. and 76.0 ° C. for mixture E-3 with 2.27% R-5011.

Mixture E-1 shows reflection in the blue spectral range in the range 438-510 nm (FWHM), mixture E-2 has selective reflection in the green spectral range in the range 490-567 nm (FWHM), and mixture E-3 Selective reflection in the red spectral range from 595 to 681 nm (FWHM).

The results of all the examples are listed in Table 13 below. The variable "α" was also calculated for each individual example. And, as expected, it was almost constant for the combination of chiral dopant R-5011 and host mixture E-0, and (15.0 ± 0.5) for the concentration used herein.

Example  9

To 97.61% of the mixture, F-0 2.39% of chiral dopant R-5011 was added. The resulting mixture F-1 has a clearing point of 86.0 ° C. and a central wavelength of selective reflection of 558 nm. The band of selective reflection is in the range 524 to 592 nm (FWHM), and Δλ / 2 is 34 nm.

Example  10 to 13

To each of these mixtures (G-0 to J-0), a predetermined amount of chiral dopant R-5011 was provided. Each concentration was 2.73%, 2.22%, 3.02% and 2.93% for each mixture G-1, H-1, I-1 and J-1.

Example  14

To the liquid crystal host mixture B-0 of Example 2, a chiral reactive mesogen (RM3 *) of the formula:

Was added to mixture B-2. This reactive mesogen RM3 * has a chiral structure and the compound used has an enantiomeric excess. To this host mixture B-0, 4.75% of RM3 * is added. Three cells are then filled with the resulting mixture. The cell for LC is made of AF glass and has an alignment layer of AL3046 (JSR, Japan). The primary cells of these cells were examined as is. The variable α was here 21.2 nm. Secondary and tertiary cells of these cells are exposed to UV radiation, each having a different dose. A high pressure mercury lamp EXECURE-w 3000 (available from HOYA Schott, Japan) is used. The intensity of the UV radiation was 100 mW / cm. A cutoff filter with a cutoff wavelength of 320 nm is placed between the lamp and the LC cell. The secondary cell is exposed to UV radiation with an energy of 22 J and the tertiary cell is exposed to 71 J.

Obviously, the selective reflection wavelength can be changed to any desired color by simply changing the intensity / energy of UV radiation.

Example  15

In this example, 1.19% chiral dopant R-5011 and 3.00% chiral reactive mesogen RM3 * were added to the liquid crystal host mixture B-0 of Example 2. Similar to Example 14, several cells were filled with the resulting mixture, treated and investigated as described in Example 14. Here, four cells were prepared. Primary cells were examined as is. Each secondary cell is exposed to UV radiation with an energy of 60 J, the third cell is exposed to 120 J and the fourth cell is exposed to 300 J.

Obviously, here also the selective reflection wavelength can be changed to any desired color by changing the intensity / energy of UV radiation.

Example  16

Now, a chiral dopant R-5011 of 1.195, a chiral reactive mesogen RM3 * of 3.00%, and a photoinitiator Irgacure 651 (abbreviated as IRG-651 (R), Shiva Corporation, Switzerland) of 0.030% of Example 2 were prepared. It was added to the liquid crystal host mixture B-0. Similar to Example 15, four cells were also prepared, processed and examined. Primary cells were also examined as is. Each secondary cell is exposed to UV radiation with an energy of 30 J, the third cell is exposed to 60 J, and the fourth cell is exposed to 120 J.

Obviously, here also the selective reflection wavelength can be changed to any desired color by changing the intensity / energy of UV radiation. The energy of UV radiation required to achieve a given wavelength shift of selective reflection is significantly lower when the photoinitiator is used as in this example, as compared to the situation in the absence of the photoinitiator as in the previous Example 15. In both cases, starting with one and the same wavelength of selective reflection (ie, 452 ± 1 nm), the longer wavelength value of a given selective reflection (eg, 598 ± 3 nm) is significantly lower than 300 J, 120 J. To reach the energy dose. This results in reduced exposure of the medium to UV radiation and increased reliability.

These results are summarized and compared in the table below.

Claims (26)

At least one compound of formula (I):

[Wherein,
R ¹ is alkyl, alkoxy, fluorinated alkyl or fluorinated alkoxy, alkenyl, alkenyloxy, alkoxyalkyl, fluorinated alkenyl or fluorinated alkenyloxy,

Is

or

ego,
L ¹¹ and L ¹² are independently of each other H or F,
X ¹ is CN or NCS,
i is 0 or 1;
At least one compound selected from the group consisting of compounds of the formulas II and III:

[Wherein,
R ² and R ³ independently of one another are alkyl, alkoxy, fluorinated alkyl or fluorinated alkoxy having 1 to 7 carbon atoms, alkenyl, alkenyloxy, alkoxyalkyl or fluorinated al having 2 to 7 carbon atoms Kenil,

To

Are independent of each other,

or

ego,
L ²¹ , L ²² , L ³¹ and L ³² are independently of each other H or F,
X ² and X ³ are independently of each other halogen, halogenated alkyl or alkoxy having 1 to 3 carbon atoms, or halogenated alkenyl or alkenyloxy having 2 or 3 carbon atoms,
Z ³ is -CH ₂ CH _2- , -CF ₂ CF _2- , -COO-, trans-CH = CH-, trans-CF = CF-, -CH ₂ O- or a single bond,
l, m, n and o are each independently 0 or 1;
Optionally at least one compound selected from the group consisting of compounds of the formulas IV and V

[Wherein,
R ⁴¹ to R ⁵² independently of one another have the meanings described for R ² in Formula II above,

And

Are independent of each other, and

Are present twice, they are also independent of each other,

or

ego,

And

Are independent of each other, and

Are present twice, they are also independent of each other,

or

ego,
Z ⁴¹ to Z ⁵² are independent of each other and, if Z ⁴¹ and / or Z ⁵¹ are present twice, they are also independent of each other: -CH ₂ CH _2- , -COO-, trans-CH = CH-, trans -CF = CF-, -CH ₂ O-, -CF ₂ O-, -C≡C- or a single bond,
p and q are independently of each other 0, 1 or 2], and
Optionally at least one chiral compound
Liquid crystal medium comprising a. The method of claim 1,
A liquid crystalline medium, characterized in that the total concentration of the compound of formula I in the medium is in the range of 1% or more and 35% or less. The method according to claim 1 or 2,
A liquid crystal medium, characterized in that the liquid crystal medium comprises a compound of formula (I-2):

Where
R ¹ and X ¹ each have the meaning described for Formula 1 above in claim 1. The method according to any one of claims 1 to 3,
A liquid crystal medium, characterized in that the liquid crystal medium comprises one or more compounds of the formula (II-2c-1):

Where
R ² has the meaning described in claim 1. The method according to any one of claims 1 to 4,
A liquid crystal medium, characterized in that the liquid crystal medium comprises at least one compound of formula III-1d-1:

Where
R ³ has the meaning described in claim 1. 6. The method according to any one of claims 1 to 5,
Liquid crystal medium, characterized in that the liquid crystal medium comprises at least one compound of the formula R-5011 or S-5011:

. The method according to any one of claims 1 to 6,
Wherein said liquid crystalline medium comprises at least one polymerizable compound. The method according to any one of claims 1 to 7,
A liquid crystal medium, characterized in that the liquid crystal medium comprises one or more compounds of the formulas V-1 and / or V-2:

Where
R ⁵¹ and R ⁵² have the meanings as defined in claim 1, respectively. A liquid crystal display comprising the liquid crystal medium according to claim 1. Use of a liquid crystal medium according to any one of claims 1 to 8 in a liquid crystal display. A process comprising: mixing at least one compound of formula (I), at least one compound of formula (II) and / or III, and at least one formula (IV) and / or V and / or VIIA and / or VIIB as claimed in claim 1 Method for producing a liquid crystal medium according to any one of claims 1 to 8. A composite material comprising a low molecular weight liquid crystal medium and a polymer obtainable from the medium according to claim 7. Use of the composite material according to claim 12 in liquid crystal displays. Process for the preparation of the composite material according to claim 12 by polymerization of the polymer precursor in a liquid crystal medium. A liquid crystalline medium comprising at least one compound having a nematic phase and at least one chiral reactive mesogen. The method of claim 15,
Wherein the liquid crystal medium comprises one or more non-reactive chiral compounds (ie, chiral dopants). The method according to claim 15 or 16,
And the liquid crystal medium further comprises a photoinitiator. The method according to any one of claims 15 to 17,
Wherein the liquid crystal medium has a selective reflection wavelength in the near ultraviolet (eg, greater than 250 nm) or visible range of the electromagnetic spectrum. 20. The method according to any one of claims 15 to 19,
Liquid crystal medium, characterized in that the liquid crystal medium is a medium according to any one of claims 1 to 8. 20. A liquid crystal display comprising the liquid crystal medium according to any one of claims 15 to 19. Use of a liquid crystal medium according to any one of claims 15 to 19 in a liquid crystal display. 20. A process for producing a liquid crystal medium according to any one of claims 15 to 19, characterized in that at least one compound having a nematic phase and at least one chiral reactive mesogen are mixed. 20. A composite material comprising a low molecular weight liquid crystalline medium and a polymer obtainable from the medium according to claim 15. Use of the composite material according to claim 23 in a liquid crystal display. Process for the preparation of the composite material according to claim 23 by polymerization of the polymer precursor in a liquid crystal medium. A method for adjusting the color and / or bandwidth of the selective reflection of the composite material according to claim 23 by exposure of the medium to UV radiation.

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