Liquid crystalline material

• US 5,543,075 A
• Filed: 06/01/1994
• Issued: 08/06/1996
• Est. Priority Date: 10/02/1992
• Status: Expired due to Fees

• Current Assignee: Merck Patent GmbH (Merck & Co., Inc.)
• Original Assignee: Merck Patent GmbH (Merck & Co., Inc.)
• Inventors: Coates, David, Parri, Owain L., Goulding, Mark J., Brown, Emma J.
• Primary Examiner(s): WU, SHEAN CHIU
• Application Number:
  US08/244,518
• Time in Patent Office: 797 Days
• Field of Search: 252/299.01, 252/299.61, 252/299.66, 359/103, 359/52, 428/1
• US Class Current: 252/299.01
• CPC Class Codes: C09K 19/38 Polymers
• CPC Class Codes: C09K 19/542 Macromolecular compounds
• CPC Class Codes: C09K 2323/031 Polarizer or dye

Abstract

The invention relates to a liquid crystalline material in the form of an anisotropic gel consisting of a polymerized monotropic or enantiotropic liquid crystalline material and a low-molecular weight liquid crystalline material, wherein the polymerized material a) forms a permanently oriented network in the low-molecular liquid crystalline material b), characterized in that the low-molecular weight liquid crystalline material b) exhibits a dielectric anisotropy Δε<-0.5, and to a display cell with such a material.

Claims

1. A liquid crystalline material in the form of an anisotropic gel consisting of a polymerized monotropic or enantiotropic liquid crystalline material and a low-molecular weight liquid crystalline material, wherein the polymerized material a) forms a permanently oriented network in the low-molecular weight liquid crystalline material b), which the low-molecular weight liquid crystalline material b) is a liquid crystalline medium which exhibits a dielectric anisotropy Δ

ε

≦

-0.5 and comprises at least two components wherein at least one component is a mesogenic compound comprising a structure element of formula 1 ##STR62##

2. A liquid crystalline material of claim 1, wherein material b) forms a continuous phase around the network of material a).

3. A liquid crystalline material of claim 1, wherein material a) is an acrylate, epoxy compound, vinyl ether compound or thiolene compound.

5. A liquid crystalline material according to claim 1 , of the formula Ia ##STR64## in which R¹ is an alkyl or an alkenyl group each having up to 12 C atoms and in which, in addition one or more non-adjacent CH₂ groups may be replaced by a divalent radical selected from --O--, --S--, --CO--, --O--CO-- and --CO--O--,

A¹ is a divalent ring structure selected from ##STR65## R² is a thio alkyl or an alkoxy group each having up to 7 C atoms and in which, in addition one or more non-adjacent CH₂ groups may be replaced by a divalent radical selected from --O--, --CO-- and --CH═

CH--, and L¹ to L⁴ are each H or F with the proviso that L¹ ═

L² ═

F and/or L³ ═

L⁴ ═

F.

6. A liquid crystalline material of claim 3 wherein the material a) is a polymerizable rod-like compound of the formula II

7. A liquid crystalline material of claim 3, wherein the material a) is a acrylate of formula II ##STR68## wherein A is --O--, --CO--O--, --O--CO-- or a single bond, B is selected from --(CH₂)_s -- ##STR69## with X being CH₃, Cl or F and r being 0, 1 or 2, s is an integer between 1 and 6, and

n and m are integers between 0 and 20.

8. A liquid crystalline material as claimed in claim 1, characterized in that material a) is present in the gel in a quantity of 1-50% by weight.

9. A liquid crystalline material as claimed in claim 8, characterized in that the material a) is present in the gel in a quantity of 5-20% by weight.

10. A liquid crystalline material according to claim 1, wherein the material b) exhibits a dielectric anisotropy Δ

ε

<

-1 and an optic anisotropy Δ

n≧

0.15.

11. A liquid crystalline material of claim 10, wherein the material b ) contains at least one mesogenic tolane derivative comprising a structure element of formula 6 ##STR70## in which A, B and D are each independently CH, CF or N.

12. A liquid crystalline material according to claim 11, wherein the tolane derivative exhibits a structure element of formula 6a ##STR71##

13. A liquid crystalline material as claimed in claim 1, wherein the material b) contains at least a mesogenic compound comprising a structure element of formula 7 ##STR72## wherein L¹ and L² are each independently H or F,

Q is --(O)_t --(CH₂)_u --(CF₂)_v --(CFH)_x

t being 0 or 1

u being an integer between 0 and 8

v being an integer between 0 and 9

x being an integer between 0 and 8 with the proviso that the sum of v and x is at least 1, or a single bond, and

Y is F or Cl.

14. A display cell comprising two opposite plates which are transparent to light as the substrate, which plates are provided with an electrode of a material which is transparent to light on the sides facing each other, said electrode carrying an orientation layer and a sealing material being provided between the ends of the plates, a liquid crystalline material being introduced in the space between the plates and the sealing material, wherein in that the liquid crystalline material is composed of at least two different liquid crystalline materials, as indicated in claim 1.

15. A liquid crystalline material according to claim 5, which is an alkylthiobiphenyl of the formula Ia1 ##STR73## wherein n is 1 to 7.

16. A liquid crystalline material of claim 15, wherein L³ ═

L⁴ ═

F, L¹ ═

L² ═

H and R¹ is a straight-chain alkoxy group of up to 12 C atoms.

17. A liquid crystalline material of claim 16, having n=1.

18. A liquid crystalline material according to claim 5, which is an alkylthiobiphenyl of the formula Ia2 ##STR74## wherein n is 1 to 7.

4. A liquid crystalline material in the form of an anisotropic gel consisting of a polymerized monotropic or enantiotropic liquid crystalline material and a low-molecular weight liquid crystalline material, wherein the polymerized material a) forms a permanently oriented network in the low-molecular weight liquid liquid crystalline material b), which low-molecular weight liquid crystalline material b) is a liquid crystalline medium which exhibits a dielectric anisotropy Δ

ε

≦

-0.5, and comprises at least two components wherein at least one component is a mesogenic compound of formulae I ##STR63## wherein R¹ and R² are each independently alkyl or alkenyl with up to 16 C atoms, in which one or two non-adjacent CH₂ groups may be replaced by --O--, --S--, --CO--O--, --O--CO-- or --O--CO--O--,

A¹ and A² are each independently optionally fluorinated 1,4-phenylene in which one or two CH₂ groups may be replaced by O,

Z¹ and Z² are each independently --CO--O--, --O--CO--, --OCH₂ --, --CH₂ O--, --CH₂ CH₂ --, --C.tbd.C--, --C.tbd.C--C.tbd.C-- or a single bond, and

m and n are each independently 0, 1, 2 or 3 with the proviso that the sum of m+n is 1, 2 or 3.

19. A liquid crystalline material in the form of an anisotropic gel consisting of a polymerized monotropic or enantiotropic liquid crystalline material and a low-molecular weight liquid crystalline material, wherein the polymerized material a) is present in the gel in an amount of 1-50% by weight, and forms a permanently oriented network in the low-molecular weight liquid crystalline material b) , which low-molecular weight liquid crystalline material b) is a liquid crystalline medium which exhibits a dielectric anisotropy Δ

ε

≦

-0.5, and comprises at least two components wherein at least one component is a mesogenic compound of formula I ##STR75## wherein R¹ and R² are each independently alkyl or alkenyl with up to 16 C atoms, in which one or two non-adjacent CH₂ groups may be replaced by --O--, --S--, --CO--O--, --O--CO-- or --O--CO--O--,

A¹ and A² are each independently optionally fluorinated 1,4-phenylene in which one or two CH₂ groups may be replaced by O,

Z¹ and Z² are each independently --CO--O--, --O--CO--, --OCH₂ --, --CH₂ O--, --CH₂ CH₂ --, --C.tbd.C--, --C.tbd.C--C.tbd.C-- or a single bond, and

m and n are each independently 0, 1, 2 or 3 with the proviso that the sum of m+n is 1, 2 or 3.