Liquid-crystal alignment film

• US 6,001,277 A
• Filed: 07/16/1998
• Issued: 12/14/1999
• Est. Priority Date: 05/26/1995
• Status: Expired due to Term

• Current Assignee: Hitachi Chemical Company Limited (Resonac Holdings Corp.)
• Original Assignee: Hitachi Chemical Company Limited (Resonac Holdings Corp.)
• Inventors: Honda, Yutaka, Johar, Perminder Singh, Ohta, Naoto, Miyadera, Nobuo, Fukuchi, Iwao, Ichimura, Kunihiro, Miyadera, Yasuo
• Primary Examiner(s): WU, SHEAN CHIU
• Application Number:
  US08/952,892
• Time in Patent Office: 516 Days
• Field of Search: 252/299.4, 349/123, 349/128, 349/134, 349/135, 349/136, 428/1.1, 428/1.2, 428/1.25
• US Class Current: 252/299.4
• CPC Class Codes: C09K 2323/02 Alignment layer characterised by chemical composition
• CPC Class Codes: G02F 1/133711 by organic films, e.g. polymeric films
• CPC Class Codes: G02F 1/133788 by light irradiation, e.g. linearly polarised light photo-polymerisation

Abstract

Related to a liquid-crystal alignment film that can align liquid-crystal molecules without resort to the rubbing.

The liquid-crystal alignment film of the present invention comprises a resin (e.g., a polyimide) containing a photoisomerizable and dichroic structural unit (e.g., a stilbene derivative), and is furnished with the ability to align liquid-crystal molecules when a film formed of the resin is irradiated with linearly polarized light; the ability to align liquid-crystal molecules being held and fixed.

The liquid-crystal alignment film of the present invention is used in electric-filed driven type liquid-crystal display devices.

Claims

1. A liquid-crystal alignment film used in a liquid-crystal display device comprising a pair of substrates each provided with a liquid-crystal alignment film and on at least one of which an electrode is formed, and a liquid crystal held between the substrates,

wherein said liquid-crystal alignment film comprises a resin which is chemically combined with a first constituent unit wherein said first constituent unit is photoisomerizable and dichroic;

and

said liquid-crystal alignment film is furnished with the ability to align liquid-crystal molecules when a film formed of said resin is irradiated with linearly polarized light;

the ability to align liquid-crystal molecules being held and fixed.

2. The liquid-crystal alignment film according to claim 1, wherein said resin has a reactive functional group.

3. The liquid-crystal alignment film according to claim 1, wherein said first constituent unit has a reactive functional group.

4. The liquid-crystal alignment film according to claim 1, which is formed of a material prepared by adding a compound having a reactive functional group to said resin.

5. The liquid-crystal alignment film according to any one of claims 1 to 4, wherein said first constituent unit is at least one selected from the group consisting of an azobenzene, a stibene, a spiropyran, a spirobenzopyran, an α

-aryl-β

-keto-acid, an α

-hydrazono-β

-keto-acid, a chalcone, an azo compound, a benzylidenephthalimidene, a hemithioindigo, a thioindigo, a spiroxyazine, a cynnamaldehyde, a retinal, a fulgide, a diarylethene, a polymethine compound, a benzothiazolinospiropyran, a benzoxopyran spiropyran, and an isomer or hetero-atom-substituted product of any of these.

6. The liquid-crystal alignment film according to any one of claims 1 to 4, wherein said resin is at least one of;

a resin containing a second constituent unit represented by Formula (1);

##STR29## wherein Y'"'"'s are each a direct-bonded or divalent functional group and may be the same or different from each other;

Z is a divalent organic group;

Q'"'"'s are each N or CR₄ and may be the same or different;

Ar₁ and Ar₂ are each an aromatic group which may have a substituent;

R₁, R₂, R₃ and R₄ are each a hydrogen atom, an alkyl group which may have a substituent or an aryl group which may have a substituent, and may be the same or different from each other; and

n is an integer of from 0 to 20;

provided that either Y'"'"'s is directly bonded when n is 0;

a resin containing a third constituent unit represented by Formula (2);

##STR30## wherein Y'"'"'s are each a direct-bonded or divalent functional group and may be the same or different from each other;

Z is a divalent organic group;

Ar₁ and Ar₂ are each an aromatic group which may have a substituent;

R₁, R₂, and R₃ are each a hydrogen atom, an alkyl group which may have a substituent or an aryl group which may have a substituent, and may be the same or different from each other; and

n is an integer of from 0 to 20;

provided that either Y'"'"'s is directly bonded when n is 0;

a resin containing a fourth constituent unit represented by Formula (3);

##STR31## wherein Y'"'"'s are each a direct-bonded or divalent functional group and may be the same or different from each other;

Ar₁, Ar₂ and Ar₃ are each an aromatic group which may have a substituent;

Q'"'"'s are each N or CR₄ and may be the same or different;

R is a divalent organic group containing a diamine residual group; and

R₄ is a hydrogen atom, an alkyl group which may have a substituent or an aryl group which may have a substituent, and may be the same or different from each other;

a resin containing a fifth constituent unit represented by Formula (4);

##STR32## wherein Y'"'"'s are each a direct-bonded or divalent functional group and may be the same or different from each other;

Ar₁, Ar₂ and Ar₃ are each an aromatic group which may have a substituent;

Q'"'"'s are each N or CR₄ and may be the same or different;

R is a divalent organic group containing a diamine residual group; and

R₄ is a hydrogen atom, an alkyl group which may have a substituent or an aryl group which may have a substituent, and may be the same or different from each other; and

P'"'"'s are each a hydrogen atom or a monovalent organic group;

a resin containing a sixth constituent unit represented by Formula (5);

##STR33## wherein Y'"'"'s are each a direct-bonded or divalent functional group and may be the same or different from each other;

Z is a divalent organic group;

Ar₁, Ar₂ and Ar₃ are each an aromatic group which may have a substituent;

Q'"'"'s are each N or CR₄ and may be the same or different;

R is a tetravalent organic group containing an acid dianhydride residual group;

R₄ is a hydrogen atom, an alkyl group which may have a substituent or an aryl group which may have a substituent, and may be the same or different from each other; and

n is an integer of from 0 to 20;

provided that either Y'"'"'s is directly bonded when n is 0;

a resin containing a seventh constituent unit represented by Formula (6);

##STR34## wherein Y'"'"'s are each a direct-bonded or divalent functional group and may be the same or different from each other;

Z is a divalent organic group;

Ar₁, Ar₂ and Ar₃ are each an aromatic group which may have a substituent;

Q'"'"'s are each N or CR₄ and may be the same or different;

R is a tetravalent organic group containing an acid dianhydride residual group;

R₄ is a hydrogen atom, an alkyl group which may have a substituent or an aryl group which may have a substituent, and may be the same or different from each other;

n is an integer of from 0 to 20;

provided that either Y'"'"'s is directly bonded when n is 0; and

P'"'"'s are each a hydrogen atom or a monovalent organic group;

a resin containing a eighth constituent unit represented by Formula (7);

##STR35## wherein Y'"'"'s are each a direct-bonded or divalent functional group and may be the same or different from each other;

Z is a divalent organic group;

Ar₁, Ar₂ and Ar₃ are each an aromatic group which may have a substituent;

Q'"'"'s are each N or CR₄ and may be the same or different;

R is a trivalent organic group;

R₄ is a hydrogen atom, an alkyl group which may have a substituent or an aryl group which may have a substituent, and may be the same or different from each other; and

n is an integer of from 0 to 20;

provided that either Y'"'"'s is directly bonded when n is 0;

a resin containing a ninth constituent unit represented by Formula (8);

##STR36## wherein Y'"'"'s are each a direct-bonded or divalent functional group and may be the same or different from each other;

Z is a divalent organic group;

Ar₁, Ar₂ and Ar₃ are each an aromatic group which may have a substituent;

Q'"'"'s are each N or CR₄ and may be the same or different;

R is a trivalent organic group;

R₄ is a hydrogen atom, an alkyl group which may have a substituent or an aryl group which may have a substituent, and may be the same or different from each other;

n is an integer of from 0 to 20;

provided that either Y'"'"'s is directly bonded when n is 0; and

P is a hydrogen atom or a monovalent organic group;

a resin containing a tenth constituent unit represented by Formula (9);

##STR37## wherein Y is a direct-bonded or divalent functional group and may be the same or different from each other;

Ar₁, Ar₂ and Ar₃ are each an aromatic group which may have a substituent; and

Q'"'"'s are each N or CR₄ and may be the same or different, where R₄ is a hydrogen atom, an alkyl group which may have a substituent or an aryl group which may have a substituent and may be the same or different from each other;

a resin containing a eleventh constituent unit represented by Formula (10);

##STR38## wherein Y is a direct-bonded or divalent functional group and may be the same or different from each other;

Ar₁, Ar₂ and Ar₃ are each an aromatic group which may have a substituent;

Q'"'"'s are each N or CR₄ and may be the same or different, where R₄ is a hydrogen atom, an alkyl group which may have a substituent or an aryl group which may have a substituent and may be the same or different from each other; and

P is a hydrogen atom or a monovalent organic group;

a resin containing a twelfth constituent unit represented by Formula (11);

##STR39## wherein Ar₁ and Ar₂ are each an aromatic group which may have a substituent;

R is a tetravalent organic group containing an acid dianhydride residual group; and

Q'"'"'s are each N or CR₄ and may be the same or different, where R4 is a hydrogen atom, an alkyl group which may have a substituent or an aryl group which may have a substituent and may be the same or different from each other;

a resin containing a thirteenth constituent unit represented by Formula (12);

##STR40## wherein Ar₁ and Ar₂ are each an aromatic group which may have a substituent;

R is a tetravalent organic group containing an acid dianhydride residual group; and

Q'"'"'s are each N or CR₄ and may be the same or different, where R₄ is a hydrogen atom, an alkyl group which may have a substituent or an aryl group which may have a substituent and may be the same or different from each other;

a resin containing a fourteenth constituent unit represented by Formula (13);

##STR41## wherein Ar₁ and Ar₂ are each an aromatic group which may have a substituent;

R is a trivalent organic group;

Q'"'"'s are each N or CR₄ and may be the same or different, where R₄ is a hydrogen atom, an alkyl group which may have a substituent or an aryl group which may have a substituent and may be the same or different from each other; and

P is a hydrogen atom or a monovalent organic group;

a resin containing a fifteenth constituent unit represented by Formula (14);

##STR42## wherein Ar₁ and Ar₂ are each an aromatic group which may have a substituent;

R is a trivalent organic group;

Q'"'"'s are each N or CR4 and may be the same or different, where R₄ is a hydrogen atom, an alkyl group which may have a substituent or an aryl group which may have a substituent and may be the same or different from each other; and

P is a hydrogen atom or a monovalent organic group.

7. The liquid-crystal alignment film according to any one of claims 1 to 4, wherein said resin is formed of a polyimide obtained by allowing a tetracarboxylic dianhydride containing in at least part of the component said first constituent unit, to react with a diamine.

8. The liquid-crystal alignment film according to any one of claims 1 to 4, wherein said resin is formed of a polyimide obtained by allowing a diamine containing in at least part of the component said first constituent unit, to react with a tetracarboxylic dianhydride.

9. A treatment process for a liquid-crystal alignment film comprising the liquid-crystal alignment film according to any one of claims 1 to 4, said process comprising irradiating the surface of a substrate on one side of which a resin film has been formed, with linearly polarized light to thereby furnish the resin film with the ability to cause liquid-crystal alignment.

10. A liquid-crystal sandwiched panel comprising a first substrate on one side of which the liquid-crystal alignment film according to any one of claims 1 to 4 has been formed partly or on the whole surface and a second substrate on which a liquid-crystal alignment film which may be the same as or different from the alignment film of the first substrate has been formed;

said substrates being opposingly disposed and a liquid crystal being put between said substrates.

11. A liquid-crystal display device comprising the liquid-crystal sandwiched panel according to claim 10.

12. A process for producing a liquid-crystal display device, comprising the steps of;

opposingly disposing a first substrate on one side of which the resin film according to any one of claims 1 to 4 has been formed partly or on the whole surface and a second substrate on which a resin film which may be the same as or different from the resin film of the first substrate has been formed; and

irradiating the resin films with linearly polarized light before, after, or before and after a liquid crystal is put between the substrates.

13. The liquid-crystal alignment film according to claim 1, wherein said liquid-crystal alignment film is a film formed by a film forming process comprising the step of coating on said substrate a solution containing said resin or a precursor of said resin.