Process and materials for inducing pre-tilt in liquid crystals and liquid crystal displays

• US 5,731,405 A
• Filed: 03/29/1996
• Issued: 03/24/1998
• Est. Priority Date: 03/29/1996
• Status: Expired due to Fees

• Current Assignee: Elsicon Incorporated
• Original Assignee: Alliant Techsystems Incorporated (Northrop Grumman Corporation)
• Inventors: Gibbons, Wayne M., Shannon, Paul J., Sun, Shao-Tang
• Primary Examiner(s): HAMPTON HIGHTOWER, PATRICIA
• Application Number:
  US08/624,942
• Time in Patent Office: 725 Days
• Field of Search: 528/125, 528/128, 528/170, 528/172, 528/173, 528/171, 528/174, 528/179, 528/183, 528/185, 528/188, 528/220, 528/229, 528/350, 528/353, 428/1, 428/473.5
• US Class Current: 528/353
• CPC Class Codes: C08G 73/10 Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
• CPC Class Codes: C08G 73/1039 comprising halogen-containing substituents
• CPC Class Codes: C08G 73/1085 Polyimides with diamino moieties or tetracarboxylic segments containing heterocyclic moieties
• CPC Class Codes: C09K 2323/025 Polyamide
• CPC Class Codes: C09K 2323/027 Polyimide
• CPC Class Codes: C09K 2323/0271 Polyimidfluoride
• CPC Class Codes: C09K 2323/031 Polarizer or dye
• CPC Class Codes: G02F 1/133723 Polyimide, polyamide-imide
• CPC Class Codes: G02F 1/133788 by light irradiation, e.g. linearly polarised light photo-polymerisation
• CPC Class Codes: Y10T 428/31721 Of polyimide

Abstract

A process for inducing pre-tilt in alignment of a liquid crystal medium comprising exposing at least one optical alignment layer, comprising anisotropically absorbing molecules and hydrophobic moieties, to polarized light; the polarized light having a wavelength within the absorption band of said anisotropically absorbing molecules; wherein the exposed anisotropically absorbing molecules induce alignment of the liquid crystal medium at an angle + and -θ with respect to the direction of the polarization of the incident light beam and along the surface of the optical alignment layer, and induce a pre-tilt at an angle Φ with respect to the surface of the optical alignment layer and applying a liquid crystal medium to said optical alignment layer, is described. The invention also is directed to liquid crystal display elements made by the process of the invention and to novel polyimide compositions that are useful as optical alignment layers in the invention.

Claims

1. A polyimide composition which is the reaction product of at least one diaryl ketone tetracarboxylic dianhydride, at least one hydrophobic diamine and at least one alicyclic tetracarboxylic anhydride, which comprises at least two structural elements of the formulas IV and V ##STR43## wherein Y is a divalent radical selected from the formulas II and III ##STR44## ##STR45## wherein Z is selected, independently, from the group consisting of --S--, --O--, --SO₂ --, --CH₂ --, --C(CF₃)₂ --, --C(O)--, --CH₂ CH₂ --, --NR-- and a covalent bond wherein R is a C₁ -C₄ hydrocarbon chain;

X is independently selected from R₁, --O--R₁, --S--R₁, --N(R₂)--R₁ ;

wherein R₁ is independently selected from C₄ -C₂₀ perfluorinated alkyl chain, C₄ -C₂₀ partially fluorinated alkyl chain, and C₁₀ -C₂₀ hydrocarbon chain;

X₁ is independently selected from X and II;

R₂ is selected, independently, from H, C₁ -C₉ hydrocarbon chain and R₁ ;

X₂ is independently selected from the group consisting of H, CL, F, Br, R₃ and R₃ O--, wherein R₃ is independently selected from C₁ -C₃ perflourinated alkyl chain, C₁ -C₃ partially flourinated alkyl chain and C₁ -C₈ hydrocarbon chain;

m is 1 or 0; and

P is a tetravalent organic radical derived from said alicyclic tetracarboxylic dianhydride containing at least four carbon atoms, no more than one carbonyl group of the dianhydride being attached to any one carbon atom of the tetravalent radical.

2. An composition of claim 1 wherein the copolymer comprises a ratio of structural elements of formula IV and V of 1:

10 to 99;

1.

3. A composition of claim 1 wherein the hydrophobic diamine comprises 1.0 to 50 mol % of the diamine component.

4. A composition of claim 1 wherein the hydrophobic diamine comprises 1.0 to 15 mol % of the diamine component.

5. A composition of claim 2 wherein the copolyimide is derived from, additionally, at least one diaminobenzophenone, additionally comprising at least one structural element of formulas VII and VIII ##STR46## wherein Z, X₂, P and m are as described in claim 1.

6. A composition of claim 1 wherein the alicyclic tetracarboxylic dianhydride is selected from the group consisting of 5-(2,5-dioxotetrahydro)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride, 2,3,5-tricarboxycyclopentaneacetic acid dihydride, 1,2,3,4-butanetetracarboxylic acid dihydride and cyclobutanetetracarboxylic acid dianhydride.

7. A composition of claim 1, wherein the alicyclic tetracarboxylic dianhydride is 5-(2,5-dioxotetrahydro)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride.

8. A composition of claim 1 wherein the hydrophobic diamine is selected from the group consisting of 4-(1H,1H-pentadecafluoro-1-octyloxy)-1,3-benzenediamine, 4-(1H,1H,11H-eicosafluoro-1-decyloxy)-1,3-benzenediamine, 4-(1-octadecyloxy)-1,3-benzenediamine, 4-(1-hexadecyl)-1,3-benzenediamine and 2-(1-octadecyloxy)-1,4-benzenediamine.

9. A composition of claim 1 wherein the diaryl ketone tetracarboxylic anhydride is 3,3'"'"',4,4'"'"'-benzophenonetetracarboxylic dianhydride.

10. A polyimide composition which is the reaction product of at least one diaryl ketone tetracarboxylic dianhydride, at least one hydrophobic diamine and at least one diaminobenzophenone, which comprises at least two structural elements of the formulas IV and VII ##STR47## wherein Y is a divalent radical selected from the formulas II and III ##STR48## wherein Z is selected, independently, from the group consisting of --S--, --O--, --SO₂ --, --CH₂ --, --C(CF₃)₂ --, --C(O)--, --CH₂ CH₂ --, --NR-- and a covalent bond wherein R is a C₁ -C₄ hydrocarbon chain;

X is independently selected from R₁, --O--R₁, --S--R₁, --N(R₂)--R₁ ;

wherein R₁ is independently selected from C₄ -C₂₀ perfluorinated alkyl chain, C₄ -C₂₀ partially fluorinated alkyl chain, and C₁₀ -C₂₀ hydrocarbon chain;

X₁ is independently selected from X and H;

R₂ is selected, independently, from H, C₁ -C₉ hydrocarbon chain, and R₁ ;

X₂ is independently selected from the group consisting of H, CL, F, Br, R₃ and R₃ O--, wherein R₃ is independently selected from C₁ -C₃ perflourinated alkyl chain, C₁ -C₃ partially flourinated alkyl chain and C₁ -C₈ hydrocarbon chain; and

m is 1 or 0.

11. A composition of claim 10 wherein the diaryl ketone tetracarboxylic anhydride is 3,3'"'"',4,4'"'"'-benzophenonetetracarboxylic dianhydride and said hydrophobic diamine is selected from the group consisting of 4-(1H,1H-pentadecafluoro-1-octyloxy)-1,3-benzenediamine, 4-(1H,1H,11H-eicosafluoro-1-undecyloxy)-1,3-benzenediamine, 4-(1-octadecyloxy)-1,3-benzenediamine, 4-(1-hexadecyl)-1,3-benzenediamine and 2-(1-octadecyloxy)-1,4-benzenediamine.

12. A composition of claim 11 wherein the diaminobenzophenone is from 4,4'"'"'-diaminobenzophenone.

13. A composition of claim 10 wherein the hydrophobic diamine comprises about from 1.0 to 50 mol % of the diamine component.

14. A composition of claim 10 wherein the hydrophobic diamine comprises about from 1.0 to 15 mol % of the diamine component.

15. A polyimide composition, derived from a diamine component and a dianhydride component, for generating pre-tilt in alignment of a liquid crystal medium comprising a copolyimide derived from least one alicyclic tetracarboxylic dianhydride, at least one hydrophobic diamine and at least one diaminobenzophenone, which comprises at least two structural elements of the formulas V and VIII ##STR49## wherein Y is a divalent radical selected from the formulas II and III ##STR50## wherein Z is selected from the group consisting of --S--, --O--, --SO₂ --, --CH₂ --, --C(CF₃)₂ --, --C(O)--, --CH₂ CH₂ --, --NR-- and a covalent bond wherein R is a C₁ -C₄ hydrocarbon chain;

X is independently selected from R₁, --O--R₁, --S--R₁, --N(R₂)R₁ ;

wherein R₁ is independently selected from C₄ -C₂₀ perfluorinated alkyl chain, C₄ -C₂₀ partially fluorinated alkyl chain, and C₁₀ -C₂₀ hydrocarbon chain;

X₁ is independently selected from X and H;

R₂ is selected, independently, from H, C₁ -C₉ hydrocarbon chain and R₁ ;

X₂ is independently selected from the group consisting of H, CL, F, Br, R₃ and R₃ O--, wherein R₃ is independently selected from C₁ -C₃ perflourinated alkyl chain, C₁ -C₃ partially flourinated alkyl chain and C₁ -C₈ hydrocarbon chain; and

P is a tetravalent organic radical derived from said alicyclic tetracarboxylic dianhydride containing at least four carbon atoms, no more than one carbonyl group of the dianhydride being attached to any one carbon atom of the tetravalent radical.

16. A composition of claim 15 wherein the alicyclic tetracarboxylic dianhydride is selected from the group consisting of 5-(2,5-dioxotetrahydro)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride, 2,3,5-tricarboxycyclopentaneacetic acid dianhydride, 1,2,3,4-butanetetracarboxylic acid dianhydride and cyclobutanetetracarboxylic acid dianhydride.

17. A composition of claim 16 wherein the diaminobenzophenone is 4,4'"'"'-diaminobenzophenone.

18. A composition of claim 15 wherein the hydrophobic diamine comprises about from 1.0 to 50 mol % of the diamine component.

19. A composition of claim 15 wherein the hydrophobic diamine comprises about from 1.0 to 15 mol % of the diamine component.

20. A polyimide composition which is the reaction product of at least one diaryl ketone tetracarboxylic dianhydride, at least one hydrophobic diamine and at least one diamine derived from a radical Y₂, comprising at least one structural clement of the formulas IV and IVa ##STR51## wherein Y is a divalent radical selected from the formulas II and III ##STR52## wherein Z is selected, independently, from the group consisting of --S--, --O--, --SO₂ --, --CH₂ --, --C(CF₃)₂ --, --C(O)--, --CH₂ CH₂ --, --NR-- and a covalent bond wherein R is a C₁ -C₄ hydrocarbon chain;

X is independently selected from R₁, --O--R₁, --S--R₁, --N(R₂)--R₁ ;

wherein R₁ is independently selected from C₄ -C₂₀ perfluorinated alkyl chain, C₄ -C₂₀ partially fluorinated alkyl chain, and C₁₀ -C₂₀ hydrocarbon chain;

X₁ is independently selected from X and H;

R₂ is selected, independently, from H, C₁ -C₉ hydrocarbon chain and R₁ ;

X₂ is independently selected from the group consisting of H, CL, F, Br, R₃ and R₃ O--, wherein R₃ is independently selected from C₁ -C₃ perflourinated alkyl chain, C₁ -C₃ partially flourinated alkyl chain and C₁ -C₈ hydrocarbon chain;

m is 1 or 0; and

Y₂ is a divalent radical selected from the formulas IIa and IIIa ##STR53## wherein X₃ is independently selected from C₁ -C₃ perfluorinated alkyl chain, partially fluorinated alkyl chain or --OCF₃ ; and

X₄ is independently selected from X₃ and H.

21. A composition of claim 20 wherein the diamine derived from the radical Y₂ is selected from the group consisting of 2-(trifluoromethyl)-1,4-benzenediamine, 5-(trifluoromethyl)-1,3-benzenediamine, 2,2'"'"'-bis(trifluoromethyl)benzidene, 2,2'"'"'-bis(trifluoromethoxy)benzidene and 3,3'"'"'-bis(trifluoromethyl)benzidene.

22. A composition of claim 20 wherein the diaryl ketone tetracarboxylic dianhydride is 3,3'"'"',4,4'"'"'-benzophenonetetracarboxylic dianhydride.

23. A composition of claim 20 wherein the hydrophobic diamine comprises about from 1.0 to 50 mol % of the diamine component.

24. A composition of claim 23 wherein the hydrophobic diamine comprises about from 1.0 to 15 mol % of the diamine component.