Device containing a liquid-crystalline medium

Abstract

The present invention relates to a temperature-reactive device for the regulation of light transmission, containing a liquid-crystalline medium and a compound of formula I, capable of promoting or inducing homeotropic alignment to the adjacent liquid crystal medium at a given temperature. The invention furthermore relates to a process for the temperature-dependent control of light transmission through a layer of a liquid-crystalline medium.

Claims

1. A window which comprises a temperature-reactive device suitable for regulation of light transmission, which has A) a boundary state A with a transmission T.sub.A at a temperature below a boundary temperature .sub.A and B) a boundary state B with a transmission T.sub.B at a temperature above a boundary temperature .sub.B, whereby: .sub.A<.sub.B and T.sub.A>T.sub.B, and comprises a layer of a liquid-crystalline medium, characterized in that the liquid-crystalline medium comprises at least one liquid-crystalline compound and at least one compound of formula I,
R.sup.11-A.sup.11-(Z.sup.12-A.sup.12).sub.m-AG(I), in which, A.sup.11 and A.sup.12 each, independently of one another, denote an aryl-, heteroaryl-, heterocyclic- or alicyclic group optionally being substituted by one or more identical or different groups L, L in each case, independently of one another, denotes, halogen, CN, NO.sub.2, NCO, NCS, OCN, SCN, straight-chain or branched alkyl or alkoxy having 1 to 5 C atoms, where, in addition, one or more non-terminal CH.sub.2 groups in these radicals may each be replaced, independently of one another, by ##STR00207## in such a way that O atoms are not linked directly to one another, and in which, in addition, one or more H atoms may be replaced by halogen, Z.sup.12 in each case, independently of one another, denotes O, S, CO, COO, OCO, SCO, COS, OCOO, CONR.sup.0, NR.sup.0CO, NR.sup.0CONR.sup.00, NR.sup.0COO, OCONR.sup.0, OCH.sub.2, CH.sub.2O, SCH.sub.2, CH.sub.2S, CF.sub.2O, OCF.sub.2, CF.sub.2S, SCF.sub.2, CH.sub.2CH.sub.2, (CH.sub.2).sub.4, CF.sub.2CH.sub.2, CH.sub.2CF.sub.2, CF.sub.2CF.sub.2, CHN, NCH, NN, CHCR.sup.0, CY.sup.01CY.sup.02, CC, CHCHCOO, OCOCHCH, or a single bond, Y.sup.01 and Y.sup.02 each, independently of one another, denote H, F, Cl or CN, R.sup.0 and R.sup.00 each, independently of one another, denote H or alkyl having 1 to 12 C atoms, R.sup.11 each, independently of one another, denote an alkyl or alkoxy radical having 1 to 15 C atoms, where, in addition, one or more non-terminal CH.sub.2 groups in these radicals may each be replaced, independently of one another, by CC, CF.sub.2O, ##STR00208## in such a way that O atoms are not linked directly to one another, and in which, in addition, one or more H atoms may be replaced by halogen, AG denotes -Sp-X.sup.11 Sp denotes (CH.sub.2).sub.p, p denotes 0, 1 or 2, X.sup.11 denotes a group NH.sub.2, SH, OH, (CO)OH or a group of the formulae ##STR00209## and m denotes 0, 1 or 2, wherein the device comprises no alignment layers adjacent to the layer of the liquid-crystalline medium.

2. A window according to claim 1, wherein anchor group AG in formula I denotes NH.sub.2, SH, OH or (CO)OH.

3. A window according to claim 1, wherein m in formula I denotes 0.

4. A window according to claim 1, wherein the layer of the liquid-crystalline medium is arranged between two substrate layers.

5. A window according to claim 1, wherein the total concentration of compounds of formula I ranges from 0.01 to 10% by weight regarding the liquid-crystalline medium as a whole.

6. A window according to claim 1, which has two or more polarisers, at least one of which is arranged on one side of the layer of the liquid-crystalline medium and at least one of which is arranged on the opposite side of the layer of the liquid-crystalline medium.

7. A window according to claim 1, characterised in that transition between the two boundary states A and B with increasing temperature and the transition between the two boundary states B and A with decreasing temperature proceeds gradually via intermediate values of the transmission T.

8. A window according to claim 1, characterized in that one or more liquid crystalline compounds in the layer of the liquid crystalline medium in the boundary state A are homeotropically aligned.

9. A method comprising regulating light transmission with a window according to claim 1 for the regulation of light entry and/or energy input into an interior.

10. Process for production of the device within a window according to claim 1, comprising at least a step of providing a layer of liquid-crystalline medium, comprising at least one liquid-crystalline compound and at least one compound of formula I, onto a substrate.

11. Process for temperature-dependent control of light transmission through the device within a window according to claim 1, comprising a layer of a liquid-crystalline medium comprising at least one liquid-crystalline compound and at least one compound of formula I, wherein at least one liquid-crystalline compound of the liquid-crystalline medium changes from a homeotropic alignment to a planar alignment as a function of temperature.

12. A window which comprises a temperature-reactive device suitable for regulation of light transmission, which has A) a boundary state A with a transmission T.sub.A at a temperature below a boundary temperature .sub.A and B) a boundary state B with a transmission T.sub.B at a temperature above a boundary temperature .sub.B, whereby: .sub.A<.sub.B and T.sub.A>T.sub.B, and comprises a layer of a liquid-crystalline medium, characterized in that the liquid-crystalline medium comprises at least one liquid-crystalline compound and at least one compound of formula I,
R.sup.11-A.sup.11-(Z.sup.12-A.sup.12).sub.m-AG(I), in which, A.sup.11 and A.sup.12 each, independently of one another, denote an aryl-, heteroaryl-, heterocyclic- or alicyclic group optionally being substituted by one or more identical or different groups L, L in each case, independently of one another, denotes, halogen, CN, NO.sub.2, NCO, NCS, OCN, SCN, straight-chain or branched alkyl or alkoxy having 1 to 5 C atoms, where, in addition, one or more non-terminal CH.sub.2 groups in these radicals may each be replaced, independently of one another, by CC, CF.sub.2O, ##STR00210## in such a way that O atoms are not linked directly to one another, and in which, in addition, one or more H atoms may be replaced by halogen, Z.sup.12 in each case, independently of one another, denotes O, S, CO, COO, OCO, SCO, COS, OCOO, CONR.sup.0, NR.sup.0CO, NR.sup.0CONR.sup.00, NR.sup.0COO, OCONR.sup.0, OCH.sub.2, CH.sub.2O, SCH.sub.2, CH.sub.2S, CF.sub.2O, OCF.sub.2, CF.sub.2S, SCF.sub.2, CH.sub.2CH.sub.2, (CH.sub.2).sub.4, CF.sub.2CH.sub.2, CH.sub.2CF.sub.2, CF.sub.2CF.sub.2, CHN, NCH, NN, CHCR.sup.0, CY.sup.01CY.sup.02, CC, CHCHCOO, OCOCHCH, or a single bond, Y.sup.01 and Y.sup.02 each, independently of one another, denote H, F, Cl or CN, R.sup.0 and R.sup.00 each, independently of one another, denote H or alkyl having 1 to 12 C atoms, R.sup.11 each, independently of one another, denote an alkyl or alkoxy radical having 1 to 15 C atoms, where, in addition, one or more non-terminal CH.sub.2 groups in these radicals may each be replaced, independently of one another, by CC, CF.sub.2O, ##STR00211## in such a way that O atoms are not linked directly to one another, and in which, in addition, one or more H atoms may be replaced by halogen, AG denotes -Sp-X.sup.11 Sp denotes (CH.sub.2).sub.p, p denotes 0, 1 or 2, X.sup.11 denotes a group NH.sub.2, SH, OH, (CO)OH or a group of the formulae ##STR00212## and m denotes 0, 1 or 2, wherein the liquid-crystalline medium is arranged directly adjacent to both substrate layers.

13. A window according to claim 12, wherein anchor group AG in formula I denotes NH.sub.2, SH, -OH or (CO)OH.

14. A window according to claim 12, wherein m in formula I denotes 0.

15. A window according to claim 12, wherein the layer of the liquid-crystalline medium is arranged between two substrate layers.

16. A window according to claim 12, wherein the total concentration of compounds of formula I ranges from 0.01 to 10% by weight regarding the liquid-crystalline medium as a whole.

17. A method comprising regulating light transmission with a window according to claim 12 for the regulation of light entry and/or energy input into an interior.

18. A window according to claim 12, characterized in that one or more liquid crystalline compounds in the layer of the liquid crystalline medium in the boundary state A are homeotropically aligned.

19. Process for production of the device within a window according to claim 12, comprising at least a step of providing a layer of liquid-crystalline medium, comprising at least one liquid-crystalline compound and at least one compound of formula I, onto a substrate.

20. Process for temperature-dependent control of light transmission through the device within a window according to claim 12, comprising a layer of a liquid-crystalline medium comprising at least one liquid-crystalline compound and at least one compound of formula I, wherein at least one liquid-crystalline compound of the liquid-crystalline medium changes from a homeotropic alignment to a planar alignment as a function of temperature.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a graph of transmittance vs. temperature for entry 2.

(2) FIG. 2 is a graph of transmittance vs. temperature for entry 3.

(3) FIG. 1 shows by way of example the switching process of a device containing medium according to entry 2 and the substrate material combination Glass/Glass.

(4) It can be seen that a gradual transition from high to low transmission with increasing temperature takes place within a working range of about 48 to about 60 C. for the device according to the invention.

(5) Furthermore, FIG. 2 shows the switching process of a cell containing medium according to entry 3 and the substrate material combination of ITO/ITO.

(6) It can be seen that a gradual transition from high to low transmission with increasing temperature takes place within a working range from about 10 to about 8 C. for the device according to the invention.