Liquid crystal aligning agents for forming photo-aligning liquid crystal alignment layers, liquid crystal alignment layers and liquid crystal display devices using the same

Abstract

A photo-aligning liquid crystal aligning agent for forming a liquid crystal alignment layer capable of materializing a liquid crystal display device, which has a high transmittance while maintaining a liquid crystal aligning property, a voltage holding ratio and the like, and in which flickering is inhibited from being caused after operating for a long time. The photo-aligning liquid crystal aligning agent contains [A] polyamic acid or a derivative thereof which is synthesized by reacting tetracarboxylic acid dianhydride and diamine, and [B] polyamic acid or a derivative thereof obtained by reacting tetracarboxylic acid dianhydride having no photoreactive structure and diamine having no photoreactive structure.

Claims

1. A photo-aligning liquid crystal aligning agent containing: [A] polyamic acid or a derivative thereof having a photoreactive structure which is synthesized by reacting tetracarboxylic acid dianhydride and diamine, wherein the tetracarboxylic acid dianhydride and the diamine contain at least one tetracarboxylic acid dianhydride having a photoreactive structure and diamine having a photoreactive structure which are selected from the group of compounds represented by the following Formulas (I) to (VII), and at least one tetracarboxylic acid dianhydride having no photoreactive structure selected from the group of compounds represented by the following Formulas (AN-I) to (AN-VII), wherein a compound represented by the following Formula (AN-4-17) is required, and [B] polyamic acid or a derivative thereof obtained by reacting tetracarboxylic acid dianhydride having no photoreactive structure and diamine having no photoreactive structure:
R.sup.2CCR.sup.3(I)
R.sup.2CCCCR.sup.3(II)
R.sup.2CCCHCHR.sup.3(III)
R.sup.2CCR.sup.4CCR.sup.3(IV)
R.sup.2CCR.sup.4CHCHR.sup.3(V)
R.sup.2CHCHR.sup.3(VI)
R.sup.2NNR.sup.3(VII) in Formulas (I) to (VII), R.sup.2 and R.sup.3 each are independently a monovalent organic group having NH.sub.2 or a monovalent organic group having COOCO, and R.sup.4 is a divalent organic group having an aromatic ring, ##STR00118## ##STR00119## in Formulas (AN-I), (AN-IV) and (AN-V), plural X each are independently a single bond or CH.sub.2; in Formula (AN-II), G is a single bond, alkylene having 1 to 20 carbon atoms, CO, O, S, SO.sub.2, C(CH.sub.3).sub.2 or C(CF.sub.3).sub.2; in Formulas (AN-II) to (AN-IV), plural Y each are independently one selected from the group of the following trivalent groups: ##STR00120## at least one hydrogen of the above groups may be substituted with methyl, ethyl or phenyl; in Formulas (AN-III) to (AN-V), a ring A is a monocyclic hydrocarbon group having 3 to 10 carbon atoms or a condensed polycyclic hydrocarbon group having 6 to 30 carbon atoms; at least one hydrogen of the above group may be substituted with methyl, ethyl or phenyl; an atomic bonding coupled with the ring is connected with optional carbon constituting the ring, and two atomic bondings may be connected with the same carbon; in Formula (AN-VI), X.sup.10 is alkylene having 2 to 6 carbon atoms; Me represents methyl; and Ph represents phenyl; in Formula (AN-VII), plural G.sup.10 each are independently O, COO or OCO; and plural r each are independently 0 or 1; ##STR00121## in Formula (AN-4-17), m is 8; wherein in [B], the diamine having no photoreactive structure is at least one selected from the group of compounds represented by the following Formulas (DI-1) to (DI-12), wherein at least one compound represented by the following Formulas (DI-5-29) and (DI-9-1) is required, ##STR00122## in Formula (DI-1), m is an integer of 1 to 12; in Formulas (DI-3), (DI-5), (DI-6) and (DI-7), plural G.sup.21 each are independently a single bond, 13 NH, O, S, SS, SO.sub.2, CO, CONH, NHCO, C(CH.sub.3).sub.2, C(CF.sub.3).sub.2, (CH.sub.2).sub.m, O(CH.sub.2).sub.mO, N(CH.sub.3)C(CH.sub.2).sub.kN(CH.sub.3) or S(CH.sub.2).sub.mS; plural m each are independently an integer of 1 to 12, and k is an integer of 1 to 5; in Formulas (DI-6) and (DI-7), plural G.sup.22 each are independently a single bond, O, S, CO, C(CH.sub.3).sub.2, C(CF.sub.3).sub.2 or alkylene having 1 to 10 carbon atoms; at least one hydrogen of a cyclohexane ring and a benzene ring in Formulas (DI-2) to (DI-7) may be substituted with F, CH.sub.3, OH, CF.sub.3, CO.sub.2H, CONH.sub.2 or benzyl, and in addition thereto, in Formula (DI-4), at least one hydrogen of the benzene ring may be substituted with at least one of group represented the following Formulas (DI-4-a) to (DI-4-c): ##STR00123## in Formulas (DI-4-a) and (DI-4-b), plural R.sup.20 each are independently hydrogen or CH.sub.3; in Formulas (DI-2) to (DI-7), groups in which bonding positions are not fixed to any of carbon atoms constituting the rings show that the bonding positions thereof in the rings are optional; and the bonding position of NH.sub.2 in the cyclohexane ring or the benzene ring is an optional position excluding the bonding position of G.sup.21 or G.sup.22; ##STR00124## in Formula (DI-8), R.sup.21 and R.sup.22 each are independently alkyl having 1 to 3 carbon atoms or phenyl; plural G.sup.23 each are independently alkylene having 1 to 6 carbon atoms, phenylene or phenylene substituted with alkyl; w is an integer of 1 to 10; in Formula (DI-9), plural R.sup.23 each are independently alkyl having 1 to 5 carbon atoms, alkoxy having 1 to 5 carbon atoms or Cl; plural p each are independently an integer of 0 to 3, and q is an integer of 0 to 4; in Formula (DI-10), R.sup.24 is hydrogen, alkyl having 1 to 4 carbon atoms, phenyl or benzyl; in Formula (DI-11), G.sup.24 is CH.sub.2 or NH; in Formula (DI-12), G.sup.25 is a single bond, alkylene having 2 to 6 carbon atoms or 1,4-phenylene; and r is 0 or 1; in Formula (DI-12), groups in which bonding positions are not fixed to any of carbon atoms constituting the rings show that the bonding positions thereof in the rings are optional; in Formulas (DI-9), (DI-11) and (DI-12), the bonding positions of NH.sub.2 bonded to the benzene rings are optional positions; ##STR00125## in Formula (DI-5-29), k is an integer of 1 to 5.

2. The photo-aligning liquid crystal aligning agent as described in claim 1, wherein in [A], the photoreactive structure is present in a principal chain of the polyamic acid or the derivative thereof.

3. The photo-aligning liquid crystal aligning agent as described in claim 1, wherein in [A], the tetracarboxylic acid dianhydride having a photoreactive structure and the diamine having a photoreactive structure are at least one selected from the group of compounds represented by the following Formulas (I-1), (II-1), (III-1), (IV-1), (IV-2), (V-1), (VI-1) and (VII-1) to (VII-3): ##STR00126## ##STR00127## in Formulas (I-1), (II-1), (III-1), (IV-1), (V-1), (VI-1), (VII-1) and (VII-2), groups in which bonding positions are not fixed to any of carbon atoms constituting the rings show that the bonding positions thereof in the rings are optional; in Formula (VII-1), plural R.sup.4 each are independently CH.sub.3, OCH.sub.3, CF.sub.3 or COOCH.sub.3; and plural b each are independently an integer of 0 to 2.

4. The photo-aligning liquid crystal aligning agent as described in claim 3, wherein in [A], the tetracarboxylic acid dianhydride having a photoreactive structure and the diamine having a photoreactive structure are at least one selected from the group of compounds represented by the following Formulas (II-1-1), (VI-1-1), (VII- 1- 1) and (VII-3): ##STR00128##

5. The photo-aligning liquid crystal aligning agent as described in claim 1, wherein in [B], the tetracarboxylic acid dianhydride having no photoreactive structure is at least one selected from the group of compounds represented by the following Formulas (AN-1) to (AN-VII): ##STR00129## ##STR00130## in Formulas (AN-I), (AN-IV) and (AN-V), plural X each are independently a single bond or CH.sub.2; in Formula (AN-II), G is a single bond, alkylene having 1 to 20 carbon atoms, CO, O, S, SO.sub.2, C(CH.sub.3).sub.2 or C(CF.sub.3).sub.2; in Formulas (AN-II) to (AN-IV), plural Y each are independently one selected from the group of the following trivalent groups: ##STR00131## at least one hydrogen of the above groups may be substituted with methyl, ethyl or phenyl; in Formulas (AN-III) to (AN-V), a ring A is a monocyclic hydrocarbon group having 3 to 10 carbon atoms or a condensed polycyclic hydrocarbon group having 6 to 30 carbon atoms; at least one hydrogen of the above group may be substituted with methyl, ethyl or phenyl; an atomic bonding coupled with the ring is connected with optional carbon constituting the ring, and two atomic bondings may be connected with the same carbon; in Formula (AN-VI), X.sup.10 is alkylene having 2 to 6 carbon atoms; Me represents methyl; and Ph represents phenyl; in Formula (AN-VII), plural G.sup.10 each are independently O, COO or OCO; and plural r each are independently 0 or 1.

6. The photo-aligning liquid crystal aligning agent as described in claim 5, wherein the tetracarboxylic acid dianhydride having no photoreactive structure is at least one selected from the group of compounds represented by the following Formulas (AN-2-1), (AN-3-2) and (AN-4-17): ##STR00132## in Formula (AN-4-17), m is an integer of 1 to 12.

7. The photo-aligning liquid crystal aligning agent as described in claim 1, wherein in [A], a diamine having no photoreactive structure is at least one selected from the group of compounds represented by the following Formulas (DI-1) to (DI-17): ##STR00133## in Formula (DI-1), m is an integer of 1 to 12; in Formulas (DI-3) and (DI-5) to (DI-7), plural G.sup.21 each are independently a single bond, NH, O, S, SS, SO.sub.2, CO, CONH, NHCO, C(CH.sub.3).sub.2, C(CF.sub.3).sub.2, (CH.sub.2).sub.m, O(CH.sub.2).sub.mO, N(CH.sub.3)C(CH.sub.2).sub.kN(CH.sub.3) or S(CH.sub.2).sub.mS; plural m each are independently an integer of 1 to 12, and k is an integer of 1 to 5; in Formulas (DI-6) and (DI-7), plural G.sup.22 each are independently a single bond, O, S, CO, C(CH.sub.3).sub.2, C(CF.sub.3).sub.2 or alkylene having 1 to 10 carbon atoms; at least one hydrogen of a cyclohexane ring and a benzene ring in Formulas (DI-2) to (DI-7) may be substituted with F, CH.sub.3, OH, CF.sub.3, CO.sub.2H, CONH.sub.2 or benzyl, and in addition thereto, in Formula (DI-4), at least one hydrogen of the benzene ring may be substituted with at least one of groups represented the following Formulas (DI-4-a) to (DI-4-c): ##STR00134## in Formulas (DI-4-a) and (DI-4-b), plural R.sup.20 each are independently hydrogen or CH.sub.3; in Formulas (DI-2) to (DI-7), groups in which bonding positions are not fixed to any of carbon atoms constituting the rings show that the bonding positions thereof in the rings are optional; and the bonding position of NH.sub.2 in the cyclohexane ring or the benzene ring is an optional position excluding the bonding position of G.sup.21 or G.sup.22; ##STR00135## in Formula (DI-8), R.sup.21 and R.sup.22 each are independently alkyl having 1 to 3 carbon atoms or phenyl; plural G.sup.23 each are independently alkylene having 1 to 6 carbon atoms, phenylene or phenylene substituted with alkyl; w is an integer of 1 to 10; in Formula (DI-9), plural R.sup.23 each are independently alkyl having 1 to 5 carbon atoms, alkoxy having 1 to 5 carbon atoms or Cl; plural p each are independently an integer of 0 to 3, and q is an integer of 0 to 4; in Formula (DI-10), R.sup.24 is hydrogen, alkyl having 1 to 4 carbon atoms, phenyl or benzyl; in Formula (DI-11), G.sup.24 is CH.sub.2 or NH; in Formula (DI-12), G.sup.25 is a single bond, alkylene having 2 to 6 carbon atoms or 1,4-phenylene; and r is 0 or 1; in Formula (DI-12), groups in which bonding positions are not fixed to any of carbon atoms constituting the rings show that the bonding positions thereof in the rings are optional; in Formulas (DI-9), (DI-11) and (DI-12), the bonding positions of NH.sub.2 bonded to the benzene rings are optional positions: ##STR00136## in Formula (DI-13), G.sup.26 is a single bond, O, COO, OCO, CO, CONH, CH.sub.2O, OCH.sub.2, CF.sub.2O, OCF.sub.2 or O(CH.sub.2).sub.m, and m is an integer of 1 to 12; R.sup.25 is alkyl having 3 to 20 carbon atoms, phenyl, cyclohexyl, a group having a steroid skeleton or a group represented by the following Formula (DI-13-a); in the above alkyl, at least one hydrogen may be substituted with F, and at least one CH.sub.2 may be substituted with O; hydrogen of the above phenyl may be substituted with F, CH.sub.3, OCH.sub.3, OCH.sub.2F, OCHF.sub.2, OCF.sub.3, alkyl having 3 to 20 carbon atoms or alkoxy having 3 to 20 carbon atoms; hydrogen of the above cyclohexyl may be substituted with alkyl having 3 to 20 carbon atoms or alkoxy having 3 to 20 carbon atoms; the bonding position of NH.sub.2 bonded to the benzene ring shows that it is an optional position in the above ring: ##STR00137## in Formula (DI-13-a), G.sup.27, G.sup.28 and G.sup.29 represent a bonding group, and they each are independently a single bond or alkylene having 1 to 12 carbon atoms; at least one CH.sub.2 in the above alkylene may be substituted with O, COO, O, CONH or CHCH; a ring B.sup.21, a ring B.sup.22, a ring B.sup.23 and a ring B.sup.24 each are independently 1,4-phenylene, 1,4-cyclohexylene, 1,3-dioxane-2,5-diyl, pyrimidine-2,5-diyl, pyridine-2,5-diyl, naphthalene-1,4-diyl, naphthalene-1,5-diyl, naphthalene-2,6-diyl, naphthalene-2,7-diyl or anthracene-9,10-diyl; in the ring B.sup.21, the ring B.sup.22, the ring B.sup.23 and the ring B.sup.24, at least one hydrogen may be substituted with F or CH.sub.3; s, t and u each are independently an integer of 0 to 2, and a total thereof is 1 to 5; when s, t or u is 2, two bonding groups in the respective parentheses may be the same or different, and two rings may be the same or different; R.sup.26 is F, OH, alkyl having 1 to 30 carbon atoms, fluorine-substituted alkyl having 1 to 30 carbon atoms, alkoxy having 1 to 30 carbon atoms, CN, OCH.sub.2F, OCHF.sub.2 or OCF.sub.3, and at least one CH.sub.2 in the above alkyl having 1 to 30 carbon atoms may be substituted with a divalent group represented by the following Formula (DI-13-b): ##STR00138## in Formula (DI-13-b), R.sup.27 and R.sup.28 each are independently alkyl having 1 to 3 carbon atoms; and v is an integer of 1 to 6; ##STR00139## in Formulas (DI-14) and (DI-15), plural G.sup.30 each are independently a single bond, CO or CH.sub.2; plural R.sup.29 each are independently hydrogen or CH.sub.3; R.sup.30 is hydrogen, alkyl having 1 to 20 carbon atoms or alkenyl having 2 to 20 carbon atoms; one hydrogen of a benzene ring in Formula (DI-15) may be substituted with alkyl having 1 to 20 carbon atoms or phenyl; in Formulas (DI-14) and (DI-15), groups in which bonding positions are not fixed to any of carbon atoms constituting the rings show that the bonding positions thereof in the rings are optional; NH.sub.2 bonded to the benzene ring shows that the bonding position thereof in the ring is optional: ##STR00140## in Formulas (DI-16) and (DI-17), plural G.sup.31 each are independently O or alkylene having 1 to 6 carbon atoms; G.sup.32 is a single bond or alkylene having 1 to 3 carbon atoms; R.sup.31 is hydrogen or alkyl having 1 to 20 carbon atoms, and at least one CH.sub.2 of the above alkyl may be substituted with O; R.sup.32 is alkyl having 6 to 22 carbon atoms; R.sup.33 is hydrogen or alkyl having 1 to 22 carbon atoms; a ring B.sup.25 is 1,4-phenylene or 1,4-cyclohexylene; r is 0 or 1; and NH.sub.2 bonded to the benzene ring shows that the bonding position thereof in the ring is optional.

8. The photo-aligning liquid crystal aligning agent as described in claim 7, wherein the diamine having no photoreactive structure is at least one of compounds represented by the following Formula (DI-5-1): ##STR00141## in Formula (DI-5-1), m is an integer of 1 to 12.

9. The photo-aligning liquid crystal aligning agent as described in claim 1, wherein in [B], the tetracarboxylic acid dianhydride having no photoreactive structure is at least one selected from the group of compounds represented by the following Formulas (AN-1-1), (AN-1-13), (AN-2-1), (AN-3-1), (AN-3-2), (AN-4-5), (AN-4-21), (AN-5-1) and (AN-16-1), and the diamine having no photoreactive structure is at least one selected from the group of compounds represented by the Formulas (DI-5-29) and (DI-9-1), and at least one compound selected from the group of compounds represented by the following Formulas (DI-1-3), (DI-2-1), (DI-4-1), (DI-5-1), (DI-5-5), (DI-5-9), (DI-5-12), (DI-5-27) to (DI-5-30), (DI-7-3), (DI-8-1) and (DI-9-1): ##STR00142## ##STR00143## ##STR00144## in Formulas (DI-5-1), (DI-5-12) and (DI-7-3), m is an integer of 1 to 12; in Formula (DI-5-29), k is an integer of 1 to 5; and in Formula (DI-7-3), n is 1 or 2.

10. The photo-aligning liquid crystal aligning agent as described in claim 9, wherein in [B], the tetracarboxylic acid dianhydride having no photoreactive structure is at least one selected from the group of the compounds represented by the following Formulas (AN-1-1), (AN-1-13), (AN-2-1), (AN-3-1), (AN-3-2) and (AN-4-5), and the diamine having no photoreactive structure is at least one selected from the group of the compounds represented by the Formulas (DI-5-29) and (DI-9-1), and optionally at least one compound selected from the group of compounds represented by the following formulas (DI-1-3), (DI-2-1), (DI-4-1), (DI-5-1), and (DI 5-5): ##STR00145## ##STR00146## in Formula (DI-5-1), m is an integer of 1 to 12.

11. The photo-aligning liquid crystal aligning agent as described in claim 1, further comprising at least one selected from the group of compounds consisting of alkenyl-substituted nadiimide compounds, compounds having a radically polymerizable unsaturated double bond, oxazine compounds, oxazoline compounds, epoxy compounds and silane coupling agents.

12. The photo-aligning liquid crystal aligning agent as described in claim 11, wherein the alkenyl-substituted nadiimide compound is at least one selected from the group of compounds consisting of bis{4-(allylbicyclo[2.2.1]hept-5-ene-2,3-dicarboxyimide)phenyl }methane, N,N-m-xylylene-bis(allylbicyclo[2.2.1]hept-5-ene-2,3-dicarboxyimide) and N,N-hexamethylene-bis(allylbicyclo[2.2.1]hept-5-ene-2,3-dicarboxyimide).

13. The photo-aligning liquid crystal aligning agent as described in claim 11, wherein the compounds having a radically polymerizable unsaturated double bond is at least one selected from the group of compounds consisting of N,N-ethylenebisacrylamide, N,N-(1,2-dihydroxyethylene)bisacrylamide, ethylenebisacrylate and 4,4-methylenebis(N,N-dihydroxyethyleneacrylateaniline).

14. The photo-aligning liquid crystal aligning agent as described in claim 11, wherein the epoxy compound is at least one selected from the group of compounds consisting of N,N,N,N-tetraglycidyl-m-xylenediamine, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, N,N,N,N-tetraglycidyl-4,4-diaminodiphenylmethane, 2-[4-(2,3-epoxypropoxy)phenyl]-2-[4-[1,1-bis[4-([2,3-epoxypropoxy]phenyl)]ethyl]phenyl]propane, 3,4-epoxycyclohexenylmethyl-3,4-epoxycyclohexenecarboxylate, N-phneylmaleimide-glycidyl methacrylate copolymers, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, paraaminophenyltrimethoxysilane and 3-aminopropyltriethoxysilane.

15. The photo-aligning liquid crystal aligning agent as described in claim 11, wherein the silane coupling agent is at least one selected from the group of compounds consisting of 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, paraaminophenyltrimethoxysilane and 3-aminopropyltriethoxysilane.

16. A photo-aligning liquid crystal alignment layer formed by the photo-aligning liquid crystal aligning agent as described in claim 1.

17. A liquid crystal display device comprising the photo-aligning liquid crystal alignment layer as described in claim 16.

18. A photo-aligning liquid crystal alignment layer formed by passing through a step of coating the photo-aligning liquid crystal aligning agent as described in claim 1 on a substrate, a step of heating and drying the substrate coated with the aligning agent and a step of irradiating the layer with a polarized UV ray.

19. A photo-aligning liquid crystal alignment layer formed by passing through a step of coating the photo-aligning liquid crystal aligning agent as described in claim 1 on a substrate, a step of heating and drying the substrate coated with the aligning agent, a step of irradiating the dried layer with a polarized UV ray and then a step of heating and baking the layer.

20. A photo-aligning liquid crystal alignment layer formed by passing through a step of coating the photo-aligning liquid crystal aligning agent as described in claim 1 on a substrate, a step of heating and drying the substrate coated with the aligning agent, a step of heating and baking the dried layer and then a step of irradiating the layer with a polarized UV ray.

Description

EXAMPLES

(1) The present invention shall be explained below with reference to examples. Evaluating methods and compounds used in the examples are shown below.

(2) <Evaluating Method of Liquid Crystal Alignment Layer>

(3) 1. Transmittance:

(4) A transmittance of the substrate on which a liquid crystal alignment layer described later was formed was measured to calculate an average value of absorbances in 380 to 780 nm. A UV and visible spectrophotometer V-660 (manufactured by JASCO Corporation) was used for a UV and visible spectrophotometer. 2. Volume Resistivity:

(5) A volume resistivity of the substrate on which a liquid crystal alignment layer described later was formed was measured. ULTRA HIGH RESISTANCE METER P8340A (manufactured by ADVANTEST Corporation) was used for a measuring device.

(6) <Tetracarboxylic Acid Dianhydride>

(7) Acid dianhydride (A1): pyromellitic acid dianhydride: (AN-3-2) Acid dianhydride (A2): 1,8-bis(3,4-phenyl dicarboxylate)octane dianhydride (AN-4-17 (m=8)) Acid dianhydride (A3): 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride (AN-2-1) Acid dianhydride (A4): azobenzene-3,3,4,4-tetracarboxylic acid dianhydride (VII-3) Acid dianhydride (A5): butanetetracarboxylic acid dianhydride (AN-1-1) Acid dianhydride (AG6): 1,2,4,5-cyclohexanetetracarboxylic acid dianhydride: (AN-3-1) Acid dianhydride (A7): 3,3,4,4-biphenyltetracarboxylic acid dianhydride: (AN-c) Acid dianhydride (A8): ethylenediaminetetraacetic acid dianhydride (AN-1-13) Acid dianhydride (A9): 5,5-p-phenylenebis(isobenzofuran-1,3-dione): (AN-16-14) Acid dianhydride (A10): 3,3,4,4-diphenylethertetracarboxylic acid dianhydride: (AN-4-21)
<Diamine> Diamine (D1): 4,4-diaminoazobenznene (VII-1-1) Diamine (D2): 4,4-diaminostilbene (VI-1-1) Diamine (D3): 4,4-diaminodiphenyl-1,4-butadiyne (II-1-1) Diamine (D4): 4,4-diaminodiphenylethane (DI-5-1 (m=2)) Diamine (D5): 4,4-diaminodiphenylbutane (DI-5-1 (m=4)) Diamine (D6): 4,4-diaminodiphenylhexane (DI-5-1 (m=6)) Diamine (D7): 4,4-diaminodiphenyloctane (DI-5-1 (m=8)) Diamine (D8): 4,4-diaminodiphenylmethane (DI-5-1 (m=1)) Diamine (D9): 2,2-dimethyl-4,4-diaminodiphenylmethane (DI-5-5) Diamine (D10): 4,4-N,N-bis(4-aminophenyl)-N,N-dimethylethylenediamine (DI-5-29 (k=2)) Diamine (D11): 4,4-N,N-bis(4-aminophenyl)piperazine (DI-9-1) Diamine (D12): 1,4-cyclohexanediamine (DI-2-1) Diamine (D13): 1,6-diaminohexane (DI-1-3) Diamine (D14): 1,4-phenylenediamine (DI-4-1) Diamine (D15): 1,8-diaminooctane (DI-1 (m=8)) Diamine (D16): 3-amino-5-(4-dodecylbenzyl)phenylamine (DI-13-2 (R.sup.34=C.sub.12H.sub.25)) Diamine (D17): 1,1-bis(4-((aminophenyl)methyl)phenyl)-4-butylcyclohexane (DI-16-2 (R.sup.40=C.sub.4H.sub.9)) Diamine (D18): 1,1-bis((aminophenoxy)phenyl)-4-(n-pentylcyclohexyl)cyclohexane (DI-16-4 (R.sup.41=C.sub.5H.sub.11)) Diamine (D19): 3,5-diamino-N-((dihydroxymethyl)methyl)benzamide: (DI-4-12) Diamine (D20): 3,5-diamino-N-((trihydroxymethyl)methyl)benzamide: (DI-4-13) Monoamine (M1): aniline
<Solvents> N-methyl-2-pyrrolidone: NMP Butyl cellosolve (ethylene glycol monobutyl ether): BC
<Additives> Additive (Ad1): 3-aminopropyltriethoxysilane Additive (Ad2): bis[4-(allylbicyclo[2.2.1]hept-5-ene-2,3-dicarboxylmide)phenyl]methane Additive (Ad3): 1,3-bis(4,5-dihydro-2-oxazolyl)benzene Additive (Ad4): 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane
<1. Synthesis of Polyamic Acid>

Synthetic Example 1

(8) A four neck flask of 100 mL equipped with a thermometer, a stirrer, a raw material-charging port and a nitrogen gas-introducing port was charged with 1.61 g of diamine (D1), 1.14 g of diamine (D5) and 50 g of dehydrated NMP, and the mixture was dissolved by stirring under dry nitrogen flow. Then, 3.85 g of acid dianhydride (A2) and 24 g of dehydrated NMP were added thereto, and the mixture was continued to be stirred at room temperature for 24 hours. BC 20 g was added to the above reaction solution to obtain a polyamic acid solution having a polymer solid concentration of 6% by weight. This polyamic acid solution is designated as PA1. The polyamic acid contained in PA1 had a viscosity of 10 mPa.Math.s and a weight average molecular weight of 22,000.

(9) The weight average molecular weight of the polyamic acid was determined by measuring a molecular weight by means of a 2695 separation module2414 differential refractometer (manufactured by Waters Corporation) according to a GPC method and reducing it to polystyrene. The polyamic acid thus obtained was diluted by a phosphoric acid-DMF mixed solution (phosphoric acid/DMF=0.6/100: weight ratio) so that a concentration of the polyamic acid was about 2% by weight. HSPgel RT MB-M (manufactured by Waters Corporation) was used for the column, and the mixed solution described above was used for the developer to carry out the measurement on the conditions of a column temperature of 50 C. and a flow rate of 0.40 ml/minute. TSK standard polystyrene manufactured by Tosoh Corp. was used for standard polystyrene.

(10) A viscosity of the polyamic acid solution was measured at 25 C. by means of a viscometer (TV-22, manufactured by Toki Sangyo Co., Ltd.).

Synthetic Examples 2 to 36

(11) Polyamic acid solutions (PA2) to (PA36) having a polymer solid concentration of 6% by weight were prepared according to Synthetic Example 1, except that the tetracarboxylic acid dianhydride and the diamine were changed as shown in Tables 1 to 3. In Synthetic Examples 27, 29, 32 and 33 out of them, the polyamic acid solutions were prepared by adding Ad1 to Ad4 respectively as shown in Table 1. To be specific, in Synthetic Example 27, the additive Ad1 was added in a proportion of 10% by weight based on a weight of the polymer to the polyamic acid solution having a polymer solid concentration of 6% by weight which was prepared according to Synthetic Example 1 by using the tetracarboxylic acid dianhydride and the diamine each shown in Table 1; in Synthetic Example 29, the additive Ad2 was added thereto in a proportion of 20% by weight based on a weight of the polymer; in Synthetic Example 32, the additive Ad3 was added thereto in a proportion of 5% by weight based on a weight of the polymer; and in Synthetic Example 33, the additive Ad4 was added thereto in a proportion of 15% by weight based on a weight of the polymer. The measured results of a viscosity and a weight average molecular weight of the polyamic acids obtained including the results obtained in Synthetic Example 1 were summarized in Tables 1 to 3.

(12) TABLE-US-00001 TABLE 1 Syn- thetic Weight Ex- Polyamic Vis- average am- acid Tetracarboxylic acid cosity molec- ple solution dianhydride (mol %) Diamine (M1 is monoamine) (mol %) (mPa .Math. ular No. No. A1 A2 A3 A4 A10 D1 D2 D3 D4 D5 D6 D7 D16 D17 D18 D19 D20 M1 s) weight 1 PA1 100 50 50 10 22,000 2 PA2 100 50 42 16 11 23,000 3 PA3 100 50 50 12 31,000 4 PA4 100 100 13 28,000 5 PA5 100 50 50 11 18,000 6 PA6 50 50 50 50 12 16,000 7 PA7 50 50 100 12 30,000 8 PA8 100 100 10 19,000 9 PA9 100 50 50 12 27,000 10 PA10 100 50 50 11 25,000 11 PA11 100 50 50 9 24,000 12 PA12 50 50 60 35 5 13 21,000 13 PA13 30 70 70 15 15 15 19,000 14 PA14 70 30 80 20 11 9,500 15 PA15 100 90 10 10 8,900 16 PA16 50 50 80 20 14 26,000 17 PA17 50 50 80 10 10 14 23,000

(13) TABLE-US-00002 TABLE 2 Polyamic Vis- Weight Synthetic acid Tetracarboxylic acid cosity average Example solution dianhydride (mol %) Diamine (mol %) Addi- (mPa .Math. molecular No. No. A1 A3 A5 A6 A7 A8 D4 D7 D8 D9 D10 D11 D12 D13 D14 tive s) weight 18 PA18 50 50 100 50 95,000 19 PA19 50 50 100 52 110,000 20 PA20 50 50 100 50 100,000 21 PA21 95 5 90 10 56 120,000 22 PA22 95 5 100 57 125,000 23 PA23 100 80 20 63 150,000 24 PA24 100 80 20 67 155,000 25 PA25 100 100 45 59,000 26 PA26 100 100 43 62,000 27 PA27 80 20 100 Ad1 53 97,000 28 PA28 80 20 100 53 109,000 29 PA29 30 70 80 20 Ad2 51 95,000 30 PA30 100 50 50 60 98,000 31 PA31 100 100 65 79,000 32 PA32 50 50 50 50 Ad3 80 189,000 33 PA33 30 30 40 50 50 Ad4 71 167,000

(14) TABLE-US-00003 TABLE 3 Tetracarboxylic Synthetic Polyamic acid dianhydride Diamine Weight average Example acid solution (mol %) (mol %) Viscosity molecular No. No. A1 A3 A9 D1 D15 (mPa .Math. s) weight 34 PA34 100 100 13 26,000 35 PA35 100 100 11 31,000 36 PA36 100 100 55 65,000
<2. Preparation of Substrate for Evaluating Transmittance>

Example 1

(15) The polyamic acid solution (PA1) having a polymer solid concentration of 6% by weight which was prepared in Synthetic Example 1 and the polyamic acid solution (PA8) having a polymer solid concentration of 6% by weight which was prepared in Synthetic Example 18 were mixed so that PA1: PA18 was 30:70 (weight ratio), and a mixed solvent of NMP/BC=4/1 (weight ratio) was added thereto to dilute the solution to a polymer solid concentration of 4% by weight, whereby a liquid crystal aligning agent was prepared. The liquid crystal aligning agent thus obtained was used to prepare a substrate for evaluating a transmittance in the following manner.

(16) <Preparing Method of Substrate for Evaluating Transmittance>

(17) The liquid crystal aligning agent was coated on a glass substrate by means of a spinner (spin coater (1H-DX2), manufactured by Mikasa Co., Ltd.). In the subsequent examples and comparative examples, a rotation speed of the spinner was controlled according to a viscosity of the liquid crystal aligning agent so that the alignment layers were controlled to the following thicknesses. After coated, the layer was dried by heating at 80 C. for 2 minutes on a hot plate (EC Hot Plate (EC-1200N), manufactured by AS ONE Corporation), and then it was irradiated with a linearly polarized UV ray via a polarizing plate from a direction vertical to the substrate by means of Multilight ML-501C/B, manufactured by USHIO INC. In the above case, the luminous energy was measured by means of a UV ray integration actinometer UIT-150 (optical receiver UVD-S365), and the exposure time was controlled so that the exposure energy was 5.00.1 J/cm.sup.2 at a wavelength of 365 nm. The UV ray was radiated at room temperature in the air, wherein a whole part of the equipment was covered with a UV preventing film. Then, the layer was subjected to heat treatment at 230 C. for 15 minutes in a clean oven (Clean Oven (PVHC-231), manufactured by ESPEC Corp.) to form an alignment layer having a layer thickness of 10010 nm.

(18) <Evaluation of Transmittance>

(19) A transmittance of the alignment layer was measured by means of a UV-Vis spectral measuring device (V-660, manufactured by JASCO Corporation). A glass substrate on which the alignment layer was not formed was used as a reference. The measurement was carried out every 1 nm in a range of a wavelength of 380 to 780 nm at a scanning speed of 400 nm/minute. An average value of the transmittances in the wavelength region described above was designated as a transmittance of the alignment layer. It is shown that the larger the above value is, the better the transmittance is.

Examples 2 to 36 and Comparative Examples 1 to 4

(20) Substrates for evaluating a transmittance were prepared according to Example 1 to measure transmittances thereof, except that the polyamic acids as the polymer and the proportions thereof were changed as shown in Tables 4 and 5. The measured results thereof including the results obtained in Example 1 are shown in Tables 4 and 5.

(21) TABLE-US-00004 TABLE 4 Polymer used for preparing liquid crystal aligning agent Polyamic acid having Polyamic acid having photoreactive no photoreactive structure structure Transmit- Example Proportion Proportion tance No. Name (weight part) Name (weight part) (%) 1 PA1 30 PA18 70 94.6 2 PA1 30 PA19 70 93.4 3 PA1 30 PA20 70 93.5 4 PA1 30 PA21 70 95.5 5 PA1 30 PA22 70 95.7 6 PA1 30 PA23 70 95.3 7 PA1 30 PA24 70 95.2 8 PA1 30 PA25 70 94.7 9 PA1 30 PA26 70 94.2 10 PA1 30 PA27 70 95.4 11 PA1 30 PA28 70 95.4 12 PA1 30 PA29 70 94.9 13 PA1 30 PA30 70 96.9 14 PA1 30 PA31 70 94.6 15 PA2 30 PA21 70 95.3 16 PA3 30 PA21 70 95.6 17 PA4 30 PA28 70 92.4 18 PA5 30 PA28 70 93.1 19 PA6 30 PA18 70 93.3 20 PA7 30 PA18 70 90.5 21 PA8 30 PA18 70 94.5 22 PA9 30 PA19 70 94.1 23 PA10 30 PA20 70 93.8 24 PA11 30 PA20 70 93.3 25 PA1 50 PA28 50 94.2 26 PA3 50 PA22 50 93.7 27 PA1 80 PA28 20 91.1 28 PA3 80 PA22 20 91.0 29 PA1 20 PA28 80 97.0 30 PA3 20 PA22 80 96.4 31 PA12 20 PA30 80 96.8 32 PA13 15 PA31 85 97.0 33 PA14 30 PA32 70 94.0 34 PA15 15 PA31 85 96.9 35 PA16 30 PA33 70 94.1 36 PA17 15 PA33 85 96.7

(22) TABLE-US-00005 TABLE 5 Polymer used for preparing liquid crystal aligning agent Polyamic acid having Polyamic acid having photoreactive no photoreactive Comparative structure structure Transmit- Example Proportion Proportion tance No. Name (weight part) Name (weight part) (%) 1 PA34 30 PA36 70 89.5 2 PA35 30 PA36 70 85.6 3 PA34 50 PA36 50 87.8 4 PA34 30 85.1

(23) In comparing the layers having the same thickness, a content of an azobenzene structure in the liquid crystal alignment layer is large in Comparative Examples 1 to 4, and therefore the transmittances thereof are notably inferior. It can be found that the alignment layers of the present invention prepared in Examples 1 to 36 have a good transmittance and are less colored.

(24) <3. Preparation of Substrate for Evaluating Volume Resistivity>

Example 37

(25) The polyamic acid solution (PA1) having a polymer solid concentration of 6% by weight which was prepared in Synthetic Example 1 and the polyamic acid solution (PA18) having a polymer solid concentration of 6% by weight which was prepared in Synthetic Example 18 were mixed so that PA1: PA18 was 30:70 (weight ratio), and a mixed solvent of NMP/BC=4/1 (weight ratio) was added thereto to dilute the solution to a polymer solid concentration of 4% by weight, whereby a liquid crystal aligning agent was prepared. The liquid crystal aligning agent thus obtained was used to prepare a substrate for evaluating a volume resistivity in the following manner.

(26) <Preparing Method of Substrate for Evaluating Volume Resistivity>

(27) The liquid crystal aligning agent was coated on an ITO-deposited substrate by means of a spinner (spin coater (1H-DX2), manufactured by Mikasa Co., Ltd.). In the subsequent examples and comparative examples, a rotation speed of the spinner was controlled according to a viscosity of the liquid crystal aligning agent so that the alignment layers were controlled to the following thicknesses. After coated, the layer was dried by heating at 80 C. for 2 minutes on a hot plate (EC Hot Plate (EC-1200N), manufactured by AS ONE Corporation), and then it was irradiated with a linearly polarized UV ray via a polarizing plate from a direction vertical to the substrate by means of Multilight ML-501C/B, manufactured by USHIO INC. In the above case, the luminous energy was measured by means of a UV ray integration actinometer UIT-150 (optical receiver UVD-S365) manufactured by USHIO INC., and the exposure time was controlled so that the exposure energy was 5.00.1 J/cm.sup.2 at a wavelength of 365 nm. The UV ray was radiated at room temperature in the air, wherein a whole part of the equipment was covered with a UV preventing film. Then, the layer was subjected to heat treatment at 230 C. for 15 minutes in a clean oven (Clean Oven (PVHC-231), manufactured by ESPEC Corp.) to form an alignment layer having a layer thickness of 30010 nm. Then, aluminum was deposited on the ITO-deposited substrate on which the alignment layer was formed by means of a vacuum depositing equipment to form an upper electrode (electrode area: 0.2927 cm.sup.2). In this connection, a mask was provided so that the electrode area was controlled to a fixed level. This caused the alignment layer to stay in a state in which it was interposed between ITO and aluminum, whereby a substrate for evaluating volume resistivity was prepared.

(28) <Evaluation of Volume Resistivity>

(29) ULTRA HIGH RESISTANCE METER P8340A (manufactured by ADVANTEST Corporation) was used to apply a voltage of 3 V on the substrate for evaluating volume resistivity prepared and calculate a volume resistivity from an electric current value after 5 minutes. In order to compare a volume resistivity observed when a stress of light in long term operation was given to the substrate with a volume resistivity observed when a stress of light was not given thereto, the volume resistivity was measured in two states of a DARK state in which the substrate was not irradiated with a light in measuring and a LIGHT state in which the substrate was irradiated with a light of 8,000 cd/cm.sup.2 by means of LED in measuring. A change degree of the above two measured values is shown by DARK/LIGHT, and it is set as standard of whether or not a flicker is liable to be brought about. It is judged that the smaller the DARK/LIGHT is, the less liable to be brought about the flicker is and that the larger the DARK/LIGHT is, the more liable to be brought about the flicker is. The evaluation results thereof are shown in Table 6-1.

Examples 38 to 72

(30) Substrates for evaluating a volume resistivity were prepared according to Example 37 to measure volume resistivities thereof, except that the polyamic acids as the polymer and the proportions thereof were changed as shown in Table 6-1. The measured results thereof including the result obtained in Example 37 are shown in Table 6-1.

(31) TABLE-US-00006 TABLE 6-1 Polymer used for preparing liquid crystal aligning agent Polyamic acid Polyamic acid having having Volume Volume photoreactive no photoreactive resistivity resistivity structure structure DARK LIGHT Example Proportion Proportion state state No. Name (wt part) Name (wt part) (/cm.sup.2) (/cm.sup.2) DARK/LIGHT 37 PA1 30 PA18 70 7.6E+16 5.1E+16 1.5 38 PA1 30 PA19 70 6.4E+15 4.7E+14 13.6 39 PA1 30 PA20 70 4.9E+15 3.1E+14 15.8 40 PA1 30 PA21 70 2.4E+17 1.4E+17 1.7 41 PA1 30 PA22 70 4.5E+17 .sup.3E+17 1.5 42 PA1 30 PA23 70 1.8E+17 9.5E+16 1.9 43 PA1 30 PA24 70 6.6E+17 4.5E+17 1.5 44 PA1 30 PA25 70 4.3E+16 2.3E+16 1.9 45 PA1 30 PA26 70 7.1E+16 4.8E+16 1.5 46 PA1 30 PA27 70 3.3E+17 8.5E+16 3.9 47 PA1 30 PA28 70 5.3E+17 .sup.2E+16 26.5 48 PA1 30 PA29 70 .sup.6E+16 .sup.8E+15 7.5 49 PA1 30 PA30 70 4.5E+16 .sup.4E+16 1.1 50 PA1 30 PA31 70 3.9E+15 1.6E+15 2.4 51 PA2 30 PA21 70 4.3E+17 1.5E+17 2.9 52 PA3 30 PA21 70 3.3E+17 1.1E+17 3.0 53 PA4 30 PA28 70 1.2E+17 7.9E+16 1.5 54 PA5 30 PA28 70 5.1E+16 7.6E+15 6.7 55 PA6 30 PA18 70 8.5E+16 5.2E+16 1.6 56 PA7 30 PA18 70 4.7E+16 2.9E+16 1.6 57 PA8 30 PA18 70 7.3E+16 3.5E+16 2.1 58 PA9 30 PA19 70 6.6E+15 5.1E+14 12.9 59 PA10 30 PA20 70 5.4E+15 4.7E+14 11.5 60 PA11 30 PA20 70 4.9E+15 3.3E+14 14.8 61 PA1 50 PA28 50 8.3E+16 7.1E+15 11.7 62 PA3 50 PA22 50 9.6E+16 5.5E+15 17.5 63 PA1 80 PA28 20 .sup.2E+17 .sup.6E+15 33.3 64 PA3 80 PA22 20 1.2E+17 5.4E+15 22.2 65 PA1 20 PA28 80 9.8E+16 3.8E+16 2.6 66 PA3 20 PA22 80 2.3E+17 8.6E+16 2.7 67 PA12 20 PA30 80 8.5E+17 9.1E+16 9.3 68 PA13 15 PA31 85 8.3E+17 .sup.8E+16 10.4 69 PA14 30 PA32 70 2.9E+17 8.6E+16 3.4 70 PA15 15 PA31 85 2.3E+17 5.5E+16 4.2 71 PA16 30 PA33 70 9.9E+16 8.4E+16 1.2 72 PA17 15 PA33 85 1.8E+17 6.5E+16 2.8

Example 73

(32) The polyamic acid solution (PA1) having a polymer solid concentration of 6% by weight which was prepared in Synthetic Example 1 and the polyamic acid solution (PA19) having a polymer solid concentration of 6% by weight which was prepared in Synthetic Example 19 were mixed so that PA1: PA19 was 30:70 (weight ratio), and a mixed solvent of NMP/BC (weight ratio) was added thereto to dilute the solution to a polymer solid concentration of 4% by weight, whereby a liquid crystal aligning agent was prepared. The liquid crystal aligning agent thus obtained was used to prepare a substrate for evaluating a volume resistivity in the following manner.

(33) The liquid crystal aligning agent was coated on an ITO-deposited substrate by means of the spinner (spin coater (1H-DX2), manufactured by Mikasa Co., Ltd.). In the subsequent examples and comparative examples, a rotation speed of the spinner was controlled according to a viscosity of the liquid crystal aligning agent so that the alignment layers were controlled to the following thickness. After coated, the layer was dried by heating at 80 C. for 2 minutes on the hot plate (EC Hot Plate (EC-1200N), manufactured by AS ONE Corporation), and then it was irradiated with a linearly polarized UV ray via a polarizing plate from a direction vertical to the substrate by means of a UV lamp (UVL-1500M2-N1) manufactured by USHIO INC. In the above case, the luminous energy was measured by means of the UV ray integration actinometer UIT-150 (optical receiver UVD-S365) manufactured by USHIO INC., and the exposure time was controlled so that the exposure energy was 5.00.1 J/cm.sup.2 at a wavelength of 365 nm. The UV ray was radiated at room temperature in the air, wherein a whole part of the equipment was covered with a UV preventing film. Then, the layer was subjected to heat treatment at 230 C. for 15 minutes in the clean oven (Clean Oven (PVHC-231), manufactured by ESPEC Corp.) to form an alignment layer having a layer thickness of 30010 nm. Finally, the substrate after heated was annealed by heating at 120 C. for 30 minutes in the clean oven. Then, aluminum was deposited on the ITO-deposited substrate on which the alignment layer was formed by means of a vacuum depositing equipment to form an upper electrode (electrode area: 0.2927 cm.sup.2). In this connection, a mask was provided so that the electrode area was controlled to a fixed level. This caused the alignment layer to stay in a state in which it was interposed between ITO and aluminum, whereby a substrate for evaluating a volume resistivity was prepared. The volume resistivity was evaluated according to Example 37.

Examples 74 to 78

(34) Substrates for evaluating a volume resistivity were prepared according to Example 73 to evaluate volume resistivities thereof, except that the polyamic acids as the polymer and the proportions thereof were changed as shown in Table 6-2. The measured results thereof including the results obtained in Example 73 are shown in Table 6-2.

(35) TABLE-US-00007 TABLE 6-2 Polymer used for preparing liquid crystal aligning agent Polyamic acid Polyamic acid having having Volume Volume photoreactive no photoreactive resistivity resistivity structure structure DARK LIGHT Example Proportion Proportion state state No. Name (wt part) Name (wt part) (/cm.sup.2) (/cm.sup.2) DARK/LIGHT 78 PA1 30 PA19 70 6.8E+15 4.6E+14 14.8 74 PA1 30 PA27 70 3.3E+17 8.3E+16 4.0 75 PA3 30 PA21 70 3.5E+17 1.1E+17 3.2 76 PA1 50 PA28 50 8.2E+16 6.5E+15 12.6 77 PA14 30 PA32 70 2.6E+17 8.8E+16 3.0 78 PA17 15 PA33 85 1.6E+17 6.0E+16 2.7

Example 79

(36) The polyamic acid solution (PA1) having a polymer solid concentration of 6% by weight which was prepared in Synthetic Example 1 and the polyamic acid solution (PA19) having a polymer solid concentration of 6% by weight which was prepared in Synthetic Example 19 were mixed so that PA1: PA19 was 30:70 (weight ratio), and a mixed solvent of NMP/BC (weight ratio) was added thereto to dilute the solution to a polymer solid concentration of 4% by weight, whereby a liquid crystal aligning agent was prepared. The liquid crystal aligning agent thus obtained was used to prepare a substrate for evaluating a volume resistivity in the following manner.

(37) The liquid crystal aligning agent was coated on an ITO-deposited substrate by means of the spinner (spin coater (1H-DX2), manufactured by Mikasa Co., Ltd.). In the subsequent examples and comparative examples, a rotation speed of the spinner was controlled according to a viscosity of the liquid crystal aligning agent so that the alignment layers were controlled to the following thickness. After coated, the layer was dried by heating at 80 C. for 2 minutes on the hot plate (EC Hot Plate (EC-1200N), manufactured by AS ONE Corporation), and then it was irradiated with a linearly polarized UV ray via a polarizing plate from a direction vertical to the substrate by means of Multilight ML-501C/B, manufactured by USHIO INC. In the above case, the luminous energy was measured by means of the UV ray integration actinometer UIT-150 (optical receiver UVD-S365) manufactured by USHIO INC., and the exposure time was controlled so that the exposure energy was 5.00.1 J/cm.sup.2 at a wavelength of 365 nm. The substrate was heated at a temperature of 50 C. while irradiated with a UV ray. The UV ray was radiated at room temperature in the air, wherein a whole part of the equipment was covered with a UV preventing film. Then, the layer was subjected to heat treatment at 230 C. for 15 minutes in the clean oven (Clean Oven (PVHC-231), manufactured by ESPEC Corp.) to form an alignment layer having a layer thickness of 30010 nm. Then, aluminum was deposited on the ITO-deposited substrate on which the alignment layer was formed by means of a vacuum depositing equipment to form an upper electrode (electrode area: 0.2927 cm.sup.2). In this connection, a mask was provided so that the electrode area was controlled to a fixed level. This caused the alignment layer to stay in a state in which it was interposed between ITO and aluminum, whereby a substrate for evaluating a volume resistivity was prepared. The volume resistivity was evaluated according to Example 37.

Examples 80 to 84

(38) Substrates for evaluating a volume resistivity were prepared according to Example 79 to evaluate volume resistivities thereof, except that the polyamic acids as the polymer and the proportions thereof each shown in Table 6-3 were changed. The measured results thereof including the result obtained in Example 79 are shown in Table 6-3.

(39) TABLE-US-00008 TABLE 6-3 Polymer used for preparing liquid crystal aligning agent Polyamic acid Polyamic acid having having Volume Volume photoreactive no photoreactive resistivity resistivity structure structure DARK LIGHT Example Proportion Proportion state state No. Name (wt part) Name (wt part) (/cm.sup.2) (/cm.sup.2) DARK/LIGHT 79 PA1 30 PA19 70 6.2E+15 4.6E+14 13.5 80 PA1 30 PA27 70 3.0E+17 6.1E+16 4.9 81 PA3 30 PA21 70 3.3E+17 1.0E+17 3.3 82 PA1 50 PA28 50 7.3E+16 6.5E+15 11.2 83 PA14 30 PA32 70 2.4E+17 8.3E+16 2.9 84 PA17 15 PA33 85 1.6E+17 6.8E+16 2.4

Comparative Examples 5 to 8

(40) Substrates for evaluating a volume resistivity were prepared according to Example 37 to evaluate volume resistivities thereof, except that the polyamic acids as the polymer and the proportions thereof were changed as shown in Table 7. The measured results thereof are shown in Table 7.

(41) TABLE-US-00009 TABLE 7 Polymer used for preparing liquid crystal aligning agent Polyamic acid Polyamic acid having having Volume Volume photoreactive photoreactive resistivity resistivity Comparative structure structure DARK LIGHT Example Proportion Proportion state state DARK/ No. Name (wt part) Name (wt part) (/cm.sup.2) (/cm.sup.2) LIGHT 5 PA34 30 PA36 70 3.7E+16 6.6E+14 56.1 6 PA35 30 PA36 70 8.9E+16 7.7E+14 115.6 7 PA34 50 PA36 50 9.2E+16 8.4E+14 109.5 8 PA34 100 7.1E+17 5.2E+15 136.5

(42) It has been found from the results obtained in Examples 37 to 84 and Comparative Examples 5 to 8 that use of the liquid crystal alignment layer of the present invention for the liquid crystal display device makes it possible to stand a photostress exerted in long term operation, that is, inhibit a flicker from being caused.

(43) As shown above, when the alignment layer of the present invention is applied to an alignment layer for a liquid crystal display device, a high transmittance of the above alignment layer makes it possible to enhance a transmittance of the liquid crystal display device and inhibit a flicker from being caused, and therefore the liquid crystal display device is provided with sufficiently high characteristics which can stand practical use.

INDUSTRIAL APPLICABILITY

(44) Use of the liquid crystal aligning agent of the present invention makes it possible to form a liquid crystal alignment layer capable of providing a liquid crystal display device which has a high transmittance and causes fewer flickers even after operated for a long time while maintaining various characteristics such as a voltage holding ratio and the like. Thus, the liquid crystal display device which comprises the above photo-alignment layer and which is excellent in display characteristics can be provided.