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 alignment layer formed by using a photo-aligning liquid crystal aligning agent containing polyamic acid or a derivative thereof which is synthesized by using tetracarboxylic acid dianhydride having no photoreactive structure having a specific structure and diamine having no photoreactive structure having a specific structure together with at least one of tetracarboxylic acid dianhydride having a photoreactive structure and diamine having a photoreactive structure can reduce storage of residual DC in a liquid crystal display device. Further, the above alignment layer can shorten the relaxation time and can prevent afterimages from being generated.

Claims

1. A photo-aligning liquid crystal aligning agent containing a polyamic acid or derivative thereof having a photoreactive structure originating in at least one of a tetracarboxylic acid dianhydride having a photoreactive structure and a diamine having a photoreactive structure in a structural unit, wherein the polyamic acid or derivative thereof is synthesized by using a tetracarboxylic acid dianhydride having no photoreactive structure and a diamine having no photoreactive structure together with at least one of the tetracarboxylic acid dianhydride having a photoreactive structure and the diamine having a photoreactive structure; the tetracarboxylic acid dianhydride having no photoreactive structure comprises at least one compound represented by the following Formula (AN-b); the diamine having no photoreactive structure comprises at least one selected from the group of compounds represented by the following Formulas (DI-a) to (DI-c): ##STR00114## wherein in Formula (AN-b), X.sup.2 is an alkylene having 4 to 8 carbon atoms; in Formula (DI-b), R.sup.1 is hydrogen or —CH.sub.3, and a is an integer of 1 to 5; and in Formulas (DI-a) and (DI-b), 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.

2. The photo-aligning liquid crystal aligning agent as described in claim 1, wherein at least one of the tetracarboxylic acid dianhydride having a photoreactive structure and the diamine having a photoreactive structure is at least one selected from the group of compounds represented by the following Formulas (I) to (VII):
R.sup.2—C≡C—R.sup.3  (I)
R.sup.2C≡C—C≡C—R.sup.3  (II)
R.sup.2—C≡C—CH═CH—R.sup.3  (III)
R.sup.2—C≡C—R.sup.4—C≡C—R.sup.3  (IV)
R.sup.2—C≡C—R.sup.4—CH═CH—R.sup.3  (V)
R.sup.2—CH═CH—R.sup.3  (VI)
R.sup.2—N═N—R.sup.3  (VII) wherein 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 —CO—O—CO—, and R.sup.4 is a divalent organic group having an aromatic ring.

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

4. The photo-aligning liquid crystal aligning agent as described in claim 1, wherein at least one of the tetracarboxylic acid dianhydride having a photoreactive structure and the diamine having a photoreactive structure is 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): ##STR00115## wherein 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; and in Formula (VII-1), plural R.sup.5 each are independently —CH.sub.3, —OCH.sub.3, —CF.sub.3 or —COOCH.sub.3; and b is an integer of 0 to 2.

5. The photo-aligning liquid crystal aligning agent as described in claim 4, wherein at least one of the tetracarboxylic acid dianhydride having a photoreactive structure and the diamine having a photoreactive structure is at least one selected from the group of compounds represented by the following Formulas (VI-1-1), (VII-1-1) and (VII-3): ##STR00116##

6. The photo-aligning liquid crystal aligning agent as described in claim 1, wherein the diamine having no photoreactive structure is at least one selected from the group of compounds represented by the following Formulas (DI-b-1) and (DI-b-2): ##STR00117##

7. The photo-aligning liquid crystal aligning agent as described in claim 1, wherein the diamine having no photoreactive structure is the compound represented by the following Formula (DI-b-2): ##STR00118##

8. The photo-aligning liquid crystal aligning agent as described in claim 1, wherein an other tetracarboxylic acid dianhydride having no photoreactive structure which is used together with the at least one compound represented by Formula (AN-b) is at least one selected from the group of compounds represented by the following Formulas (AN-I) to (AN-VII): ##STR00119## wherein 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## wherein at least one hydrogen of the above trivalent groups may be substituted with methyl, ethyl or phenyl; in Formula (AN-II), when Y is 2-azapropane-1,2,3-triyl, G described above is not an alkylene having 1 to 20 carbon atoms, and when Y is benzene-1,2,4-triyl, G described above is not an alkylene having 1 to 8 carbon atoms or —O—; 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; wherein 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 is methyl; and Ph is phenyl; and in Formula (AN-VII), plural G.sup.10 each are independently —O—, —COO— or —OCO—; and plural r each are independently 0 or 1.

9. The photo-aligning liquid crystal aligning agent as described in claim 8, wherein the other tetracarboxylic acid dianhydride having no photoreactive structure which is used together with the at least one compound represented by Formula (AN-b) is at least one selected from the group of compounds represented by the following Formulas (AN-1-1), (AN-2-1), (AN-3-1), (AN-3-2), (AN-5-1) and (AN-16-1): ##STR00121##

10. The photo-aligning liquid crystal aligning agent as described in claim 1, wherein an other diamine having no photoreactive structure which is used together with the at least one selected from the group of the compounds represented by Formulas (DI-a) to (DI-c) is at least one selected from the group of compounds represented by the following Formulas (DI-1) and (DI-3) to (DI-17): ##STR00122## wherein in Formula (DI-1), m is an integer of 1 to 12; in Formulas (DI-3), (DI-6) and (DI-7), plural G.sup.21 each are independently a single bond, —O—, —S—, —S—S—, —SO.sub.2—, CO—, —CONH—, —NHCO—, —C(CH.sub.3).sub.2—, —C(CF.sub.3).sub.m′—, —C(CH.sub.2).sub.m′—O— or —S—(CH.sub.2).sub.m′—S—, and plural m′ each are independently an integer of 1 to 12; in Formula (DI-5), G.sup.21 is a single bond, —NH—, —O—, —S—, —S—S—, —SO.sub.2—, —CO—, —CONH—, —NHCO—, —C(CH.sub.3).sub.2—, —C(CF.sub.3).sub.2—, —C(CH.sub.2).sub.m″—, —O—(CH.sub.2).sub.m′—O—, —N—C(CH.sub.3)—(CH.sub.2).sub.k—N(CH.sub.3)— or —S—(CH.sub.2).sub.m′—S—; m′ is an integer of 1 to 12, and m″ is an integer of 6 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-3) 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 a benzene ring may be substituted with at least one group represented the following Formulas (DI-4-a) to (DI-4-c): ##STR00123## wherein in Formulas (DI-4-a) and (DI-4-b), plural R.sup.20 each are independently hydrogen or —CH.sub.3; in Formulas (DI-3) 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 to the cyclohexane ring or the benzene ring is an optional position excluding the bonding position of G.sup.21 or G.sup.22: ##STR00124## wherein 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; and 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; and p and q are not 0 at the same time; in Formula (DI-10), R.sup.24 is 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## wherein 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); wherein 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; and the bonding position of —NH.sub.2 bonded to the benzene ring shows that it is an optional position in the above ring: ##STR00126## wherein 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; wherein at least one —CH.sub.2— in the above alkylene may be substituted with —O—, —COO—, —OCO—, —CONH— or —CH═CH—; 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 each parenthesis 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): ##STR00127## wherein 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: ##STR00128## wherein 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; and 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; and —NH.sub.2 bonded to the benzene ring shows that the bonding position thereof in the ring is optional: ##STR00129## wherein 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.

11. The photo-aligning liquid crystal aligning agent as described in claim 10, wherein the other diamine having no photoreactive structure which is used together with the at least one selected from the group of the compounds represented by Formulas (DI-a) to (DI-c) is at least one selected from the group of compounds represented by the following Formulas (DI-4-1), (DI-5-9), (DI-5-12), (DI-5-27), (DI-5-30) and (DI-7-3): ##STR00130## wherein in Formula (DI-5-12) and (DI-7-3), m is an integer of 1 to 12; in Formula (DI-5-30), k is an integer of 1 to 5; and in Formula (DI-7-3), n is 1 or 2.

12. 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.

13. The photo-aligning liquid crystal aligning agent as described in claim 12, 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).

14. The photo-aligning liquid crystal aligning agent as described in claim 12, wherein the epoxy compound is at least one selected from the group of compounds consisting of N,N,N′,N′-tetraglycidyl-m-xylylenediamine, 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]pheny]ethyl]phenyl]propane, 3,4-epoxycyclohexenylmethyl-3′,4′-epoxycyclohexenecarboxylate and N-phenylmaleimide-glycidyl methacrylate copolymers.

15. The photo-aligning liquid crystal aligning agent as described in claim 12, 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 photo-aligning liquid crystal alignment layer formed by 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 to achieve a dried layer and a step of irradiating the dried layer with a polarized UV ray.

18. A photo-aligning liquid crystal alignment layer formed by 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 to achieve a dried layer, a step of irradiating the dried layer with a polarized UV ray and then a step of heating and baking the layer.

19. A photo-aligning liquid crystal alignment layer formed by 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 to achieve a dried layer, a step of heating and baking the dried layer and then a step of irradiating the layer with a polarized UV ray.

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

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 Display Device>

(3) 1. Residual DC:

(4) A DC voltage of 5 V was applied to a liquid crystal display device described later for 15 minutes, and then the device was short-circuited for 1 second. After it was released for 15 minutes, a residual DC thereof was measured, and the values in the beginning and after relaxed for 15 minutes were obtained respectively. The measuring temperature was 60° C. liquid crystal physical property-measuring system, model 6254 manufactured by TOYO Corporation was used for the measuring device. It is shown that the smaller the initial value of the residual DC is and the more largely the value after relaxed for 15 minutes is reduced from the initial value, the more the storage of residual DC is decreased and the relaxation time can be shortened and that afterimages can be prevented from being generated.

(5) 2. Aligning Property:

(6) A liquid crystal display device described later was interposed between polarizing plates in which cross Nichol prisms were disposed, and it was visually confirmed whether or not the phenomenon that when liquid crystal was injected into the cell, the liquid crystal molecules were fixed in a direction in which the liquid crystal molecules flowed, so-called flow aligning was observed

(7) Tetracarboxylic acid dianhydride>

(8) Acid dianhydride (A1): ehtylenediaminetetraacetic acid dianhydride: a compound in which X.sup.1 is —CH.sub.2CH.sub.2— in (AN-a)

(9) Acid dianhydride (A2): 1,8-bis(3,4-phenyl dicarboxylate)octane dianhydride: a compound in which X.sup.2 is —(CH.sub.2).sub.8— in (AN-b)

(10) Acid dianhydride (A3): 3,3′,4,4′-diphenylethertetracarboxylic acid dianhydride: (An-c)

(11) Acid dianhydride (A4): 1,2,4,5-cyclohexanetetracarboxylic acid dianhydride: (An-3-1)

(12) Acid dianhydride (A5): azobenznene-3,3′,4,4′-tetracarboxylic acid dianhydride: (VII-3)

(13) Acid dianhydride (A6): 5,5′-p-phenylenebis(isobenzofuran-1,3-dione): (AN-16-14)

(14) <Diamine>

(15) Diamine (D1): 4,4′-diaminoazobenznene: (VII-1-1)

(16) Diamine (D2): 4,4′-diaminostilbene: (VI-1-1)

(17) Diamine (D3): 4,4′-diaminodiphenyl-1,4-butadiyne: compound in which both of two amino groups are bonded to a para position in (II-1-1)

(18) Diamine (D4): 1,4-cyclohexanediamine: compound in which both of two amino groups are bonded to a para position in (DI-a)

(19) Diamine (D5): 3,3′-dimethyl-4,4′-diaminodiphenylmethane: compound in which a is 1, in which both of R.sup.1 are methyl bonded to a meta position and in which both of two amino groups are bonded to a para position in (DI-b)

(20) Diamine (D6): 4,4′-diaminodiphenylethane: compound in which a is 2, in which both of R.sup.1 are hydrogen and in which both of two amino groups are bonded to a para position in (DI-b)

(21) Diamine (D7): 4,4′-diaminodiphenylbutane: compound in which a is 4, in which both of R.sup.1 are hydrogen and in which both of two amino groups are bonded to a para position in (DI-b)

(22) Diamine (D8): 4,4′-N,N′-bis(4-aminophenyl)piperazine: (DI-c)

(23) Diamine (D9): 4,4′-diaminodiphenyloctane: (DI-5-31)

(24) Diamine (D10): 4,4′-diaminodiphenylhexane (DI-5-29)

(25) Diamine (D11): 1,8-diaminooctane: (DI-1-3)

(26) Diamine (D12): 1,1-bis(4-((aminophenyl)methyl)phenyl)-4-butylcyclohexane: compound in which R.sup.40 is —C.sub.4H.sub.9 in (DI-16-2)

(27) Diamine (D13): 1,1-bis((aminophenoxy)phenyl)-4-(n-hexylcyclohexyl)cyclohexane: compound in which R.sup.41 is —C.sub.7H.sub.15 in (DI-16-4)
Diamine (D14): 1,1-bis((aminophenoxy)phenyl)-4-((n-pentylcyclohexyl)ethyl)cyclohexate: compound in which R.sup.41 is —C.sub.5H.sub.11 in (DI-16-7)
Diamine (D15): 3,5-diamino-N-((dihydroxymethyl)methyl)benzamide: (DI-4-12)
Diamine (D16): 3,5-diamino-N-((trihydroxymethyl)methyl)benzamide: (DI-4-13)
<Solvent>
N-methyl-2-pyrrolidone: NMP
Butyl cellosolve (ethylene glycol monobutyl ether): BC
<Additives>
Additive (Ad1): bis[4-(allylbicyclo[2.2.1]hept-5-ene-2,3-dicarboxyimide)phenyl]methane
Additive (Ad2): 1,3-bis(4,5-dihydro-2-oxazolyl)benzene
Additive (Ad3): 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane
Additive (Ad4): 3-aminopropyltriethoxysilane

1. Synthesis of Polyamic Acid

Synthetic Example 1

(28) 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 2.27 g of diamine (D1), 0.31 g of diamine (D4) and 50 g of dehydrated NMP, and the mixture was dissolved by stirring under dry nitrogen flow. Then, 3.42 g of acid dianhydride (A1) 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 weight average molecular weight of 39,000.

(29) The weight average molecular weight of polyamic acid was determined by measuring a molecular weight by means of a 2695 separation module.Math.2414 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® 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.

Synthetic Examples 2 to 17

(30) Polyamic acid solutions (PA2) to (PA17) having a polymer solid concentration of 6% by weight were prepared according to Synthetic Example 1, except that the tetracarboxylic acid dianhydride and the polyamic acid were changed as shown in Table 1. The measured results of a weight average molecular weight of the polyamic acid obtained including the result obtained in Synthetic Example 1 were summarized in Table 1.

(31) TABLE-US-00001 TABLE 1 Polyamic acid Tetracarboxylic acid Synthetic solution dianhydride (mol %) Diamine (mol %) Example No. A1 A2 A3 A4 A5 A6 D1 D2 D3 D4 D5 D6 D7 1 PA1 100 80 20 2 PA2 100 50 50 3 PA3 70 30 50 50 4 PA4 100 50 50 5 PA5 100 50 6 PA6 70 30 50 50 7 PA7 50 50 100 8 PA8 100 50 20 9 PA9 100 50 20 10  PA10 100 50 40 11  PA11 70 30 70 15 12  PA12 50 50 90 5 13  PA13 50 50 80 14  PA14 50 50 80 10 15  PA15 100 100 16  PA16 100 100 17  PA17 100 20 Weight average Synthetic Diamine (mol %) molecular Example D8 D9 D10 D11 D12 D13 D14 D15 D16 weight 1 39,000 2 41,000 3 42,000 4 52,000 5 50 67,000 6 45,000 7 34,000 8 30 56,000 9 30 42,000 10  10 55,000 11  15 82,000 12  5 66,000 13  10 10 94,000 14  10 89,000 15  45,000 16  74,000 17  80 28,000

2. Preparation of Liquid Crystal Display Device

Example 1

(32) A mixed solvent of NMP/BC=4/1 (weight ratio) was added to the polyamic acid solution (PA1) having a polymer solid concentration of 6% by weight which was prepared in Synthetic Example 1 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 liquid crystal display device as shown below.

(33) <Preparing Method of Liquid Crystal Display Device>

(34) The liquid crystal aligning agent was coated on two glass substrates provided with ITO electrodes by means of a spinner (spin coater (1H-DX2), manufactured by Mikasa Co., Ltd.). After coated, the layer was dried by heating at 70° C. for about 1 minute 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 USHO 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 5.0±0.1 J/cm.sup.2 at a wavelength of 365 nm. 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 100±10 nm.

(35) The faces on which the alignment layers were formed in two substrates having the alignment layers formed on the ITO electrodes were oppositely disposed to form a gap for injecting a liquid crystal composition into the gap between the opposite substrates so that the polarization directions of UV rays irradiated onto the respective alignment layers were parallel, and the substrates were stuck together to prepare a vacant cell having a cell thickness of 4 μm. An injection port for injecting liquid crystal into the above vacant cell was provided in such a position that a direction in which the liquid crystal flowed in injection was almost parallel to a polarization direction of a UV ray irradiated onto the alignment layer.

(36) A liquid crystal composition A shown below was injected into the vacant cell prepared above under vacuum to prepare a liquid crystal display device.

(37) <Liquid Crystal Composition A>

(38) ##STR00113##
Physical property values: NI 100.1° C.; Δ∈ 5.1; Δn 0.093; η 2.56 mPa.Math.s

(39) The liquid crystal display device prepare above was used to measure residual DC by the method described above to find that an initial value of the residual DC was 785 mV and that the value thereof after relaxed for 15 minutes was 59 mV. Also, flow aligning was not confirmed, and the aligning property was good.

Examples 2 to 14

(40) The mixed solvent of NMP/BC=4/1 (weight ratio) was added to the respective polyamic acid solutions (PA2 to PA14) having a polymer solid concentration of 6% by weight which were prepared in Synthetic Examples 2 to 14 to dilute the solutions to a polymer solid concentration of 4% by weight, whereby liquid crystal aligning agents were prepared. The liquid crystal aligning agents thus obtained were used to prepare vacant cells by the method according to Example 1. Then, the liquid crystal composition A was injected into the above vacant cells under vacuum to prepare liquid crystal display devices to measure residual DC and confirm an aligning property in the same manners as in Example 1.

Example 15

(41) The additive (Ad1) was added in a proportion of 20% by weight based on a weight of the polymer to the polyamic acid solution (PA4) having a polymer solid concentration of 6% by weight which was prepared in Synthetic Example 4. The above polyamic acid solution is designated as PA18. The polyamic acid contained in PA18 had a weight average molecular weight of 52,000. Then, the 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 vacant cell by the method according to Example 1. Then the liquid crystal composition A was injected into the above vacant cell under vacuum to prepare a liquid crystal display device to measure residual DC and confirm an aligning property in the same manners as in Example 1.

Example 16

(42) The additive (Ad2) was added in a proportion of 20% by weight based on a weight of the polymer to the polyamic acid solution (PA4) having a polymer solid concentration of 6% by weight which was prepared in Synthetic Example 4. The above polyamic acid solution is designated as PA19. The polyamic acid contained in PA19 had a weight average molecular weight of 52,000. Then, the 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 vacant cell by the method according to Example 1. Then, the liquid crystal composition A was injected into the above vacant cell under vacuum to prepare a liquid crystal display device to measure residual DC and confirm an aligning property in the same manners as in Example 1.

Example 17

(43) The additive (Ad3) was added in a proportion of 20% by weight based on a weight of the polymer to the polyamic acid solution (PA4) having a polymer solid concentration of 6% by weight which was prepared in Synthetic Example 4. The above polyamic acid solution is designated as PA20. The polyamic acid contained in PA20 had a weight average molecular weight of 52,000. Then, the 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 vacant cell by the method according to Example 1. Then, the liquid crystal composition A was injected into the above vacant cell under vacuum to prepare a liquid crystal display device to measure residual DC and confirm an aligning property in the same manners as in Example 1.

Example 18

(44) The additive (Ad4) was added in a proportion of 10% by weight based on a weight of the polymer to the polyamic acid solution (PA4) having a polymer solid concentration of 6% by weight which was prepared in Synthetic Example 4. The above polyamic acid solution is designated as PA21. The polyamic acid contained in PA21 had a weight average molecular weight of 52,000. Then, the 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 vacant cell by the method according to Example 1. Then, the liquid crystal composition A was injected into the above vacant cell under vacuum to prepare a liquid crystal display device to measure residual DC and confirm an aligning property in the same manners as in Example 1. The measured results of residual DC in Examples 1 to 18 are shown in Table 2-1.

(45) TABLE-US-00002 TABLE 2-1 Polyamic acid Residual DC Example solution Initial After relaxed Aligning No. No. value (mV) for 15 minutes (mV) property 1 PA1 785 59 ◯ 2 PA2 534 115 ◯ 3 PA3 574 142 ◯ 4 PA4 536 111 ◯ 5 PA5 689 74 ◯ 6 PA6 746 151 ◯ 7 PA7 591 63 ◯ 8 PA8 673 129 ◯ 9 PA9 631 134 ◯ 10 PA10 530 120 ◯ 11 PA11 582 106 ◯ 12 PA12 559 118 ◯ 13 PA13 642 105 ◯ 14 PA14 583 86 ◯ 15 PA18 737 166 ◯ 16 PA19 670 128 ◯ 17 PA20 678 135 ◯ 18 PA21 610 133 ◯

Example 19

(46) The mixed solvent of NMP/BC 4/1 (weight ratio) was added to the polyamic acid solution (PA1) having a polymer solid concentration of 6% by weight which was prepared in Synthetic Example 1 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 liquid crystal display device as shown below.

(47) <Preparing Method of Liquid Crystal Display Device>

(48) The liquid crystal aligning agent was coated on two glass substrates provided with ITO electrodes by means of the spinner (spin coater (1H-DX2), manufactured by Mikasa Ltd.). After coated, the layer was dried by heating at 70° C. for about 1 minute on the hot plate (EC Hot Plate (EC-1200N), manufactured by AS ONE Corporation), and then it was irradiated (exposure energy: 5.0±0.1 J/cm.sup.2 at a wavelength of 365 nm) with a linearly polarized UV ray via a polarizing plate from a direction vertical to the substrate by means of UV lamp (UVL-1500M2-N1) manufactured by USHO INC. The conditions of irradiating with a UV ray and the method for controlling the exposure energy were based on those in Example 1. 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 100±10 nm. Finally, the substrate after heated was heated and annealed at 120° C. for 30 minutes in the clean oven.

(49) The faces on which the alignment layers were formed in two substrates having the alignment layers formed on the ITO electrodes were oppositely disposed to form a gap for injecting a liquid crystal composition into the gap between the opposite substrates so that the polarization directions of UV rays irradiated onto the alignment layers were parallel, and the substrates were stuck together to prepare a vacant cell having a cell thickness of 4 μm. An injection port for injecting liquid crystal into the above vacant cell was provided in such a position that a direction in which the liquid crystal flowed in injection was almost parallel to a polarization direction of a UV ray irradiated onto the alignment layer.

(50) The liquid crystal composition A described above was injected into the vacant cell prepared under vacuum to prepare a liquid crystal display device.

(51) The liquid crystal display device prepare above was used to measure residual DC by the method described above to find that an initial value of the residual DC was 728 mV and that the value thereof after relaxed for 15 minutes was 51 mV. Also, flow aligning was not confirmed, and the aligning property was good.

Examples 20 to 24

(52) The mixed solvent of NMP/BC=4/1 (weight ratio) was added to the respective polyamic acid solutions (PA4, PA6, PA11, PA13 and PA19) having a polymer solid concentration of 6% by weight to dilute the solutions to a polymer solid concentration of 4% by weight, whereby liquid crystal aligning agents were prepared. The liquid crystal aligning agents thus obtained were used to prepare vacant cells by the method according to Example 19. Then, the liquid crystal composition A was injected into the above vacant cells under vacuum to prepare liquid crystal display devices to measure residual DC and confirm an aligning property in the same manners as in Example 1. The measured results of the residual DC in Examples 19 to 24 are shown in Table 2-2.

(53) TABLE-US-00003 TABLE 2-2 Polyamic acid Residual DC Example solution Initial After relaxed Aligning No. No. value (mV) for 15 minutes (mV) property 19 PA1 728 51 ◯ 20 PA4 563 120 ◯ 21 PA6 700 132 ◯ 22 PA11 549 99 ◯ 23 PA13 640 101 ◯ 24 PA19 658 106 ◯

Example 25

(54) The mixed solvent of NMP/BC=4/1 (weight ratio) was added to the polyamic acid solution (PA1) having a polymer solid concentration of 6% by weight which was prepared in Synthetic Example 1 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 liquid crystal display device as shown below.

(55) <Preparing Method of Liquid Crystal Display Device>

(56) The liquid crystal aligning agent was coated on two glass substrates provided with ITO electrodes by means of the spinner (spin coater (1H-DX2), manufactured by Mikasa Co., Ltd.). After coated, the layer was dried by heating at 70° C. for about 1 minute on the hot plate (EC Hot Plate (EC-1200N), manufactured by AS ONE Corporation), and then it was irradiated (exposure energy: 5.0±0.1 J/cm.sup.2 at a wavelength of 365 nm) 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 USHO INC. The substrate was heated and maintained at a temperature of 50° C. during exposure to a UV ray. The conditions of irradiating with a UV ray and the method for controlling the exposure energy were based on those in Example 1. 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 100±10 nm.

(57) The faces on which the alignment layers were formed in two substrates having the alignment layers formed on the ITO electrodes were oppositely disposed to form a gap for injecting a liquid crystal composition into the gap between the opposite substrates so that the polarization directions of UV rays irradiated onto the alignment layers were parallel, and the substrates were stuck together to prepare a vacant cell having a cell thickness of 4 μm. An injection port for injecting, liquid crystal into the above vacant cell was provided in such a position that a direction in which the liquid crystal flowed in injection was almost parallel to a polarization direction of a UV ray irradiated onto the alignment layer.

(58) The liquid crystal composition A described above was injected into the vacant cell prepared above under vacuum to prepare a liquid crystal display device.

(59) The liquid crystal display device prepare above was used to measure residual DC by the method described above to find that an initial value of the residual DC was 764 mV and that the value thereof after relaxed for 15 minutes was 44 mV. Also, flow aligning was not confirmed, and the aligning property was good.

Examples 26 to 30

(60) The mixed solvent of NMP/BC=4/1 (weight ratio) was added to the respective polyamic acid solutions (PA4, PA6, PA11, PA13 and PA19) having a polymer solid concentration of 6% by weight to dilute the solutions to a polymer solid concentration of 4% by weight, whereby liquid crystal aligning agents were prepared. The liquid crystal aligning agents thus obtained were used to prepare vacant cells by the method according to Example 25. The liquid crystal composition A was injected into the above vacant cells under vacuum to prepare liquid crystal display devices to measure residual DC and confirm an aligning property in the same manners as in Example 1. The measured results of the residual DC in Examples 25 to 30 are shown in Table 2-3.

(61) TABLE-US-00004 TABLE 2-3 Polyamic acid Residual DC Example solution Initial After relaxed Aligning No. No. value (mV) for 15 minutes (mV) property 25 PA1 764 44 ◯ 26 PA4 528 106 ◯ 27 PA6 693 129 ◯ 28 PA11 564 95 ◯ 29 PA13 601 97 ◯ 30 PA19 629 105 ◯

Comparative Examples 1 to 3

(62) The mixed solvent of NMP/BC=4/1 (weight ratio) was added to the respective polyamic acid solutions (PA15 to PA17) having a polymer solid concentration of 6% by weight to dilute the solutions to a polymer solid concentration of 4% by weight, whereby liquid crystal aligning agents were prepared. The liquid crystal aligning agents thus obtained were used to prepare vacant cells by the method according to Example 1. The liquid crystal composition A was injected into the above vacant cells under vacuum to prepare liquid crystal display devices to measure residual DC and confirm an aligning property in the same manners as in Example 1. The measured results of the residual DC in Comparative Examples 1 to 3 are shown in Table 3

(63) TABLE-US-00005 TABLE 3 Polyamic Comparative acid Residual DC Example solution Initial After relaxed Aligning No. No. value (mV) for 15 minutes (mV) property 1 PA15 871 316 ◯ 2 PA16 1172 458 ◯ 3 PA17 1283 531 ◯

(64) It can be found from the results obtained in Examples 1 to 30 and Comparative Examples 1 to 3 that use of the liquid crystal alignment layer of the present invention for liquid crystal display devices makes it possible to control residual DC to a small initial value while maintaining an aligning property and makes it possible to shorten a relaxation time because of a small value of the residual DC after relaxation for 15 minutes.

(65) As described above, when the liquid crystal alignment layer of the present invention is applied to an alignment layer for liquid crystal display devices, afterimages can be inhibited from being generated, and the aligning property is good. Accordingly, it can be found that the liquid crystal alignment layer of the present invention has satisfactory characteristics which can stand practical use.

INDUSTRIAL APPLICABILITY

(66) Use of the liquid crystal aligning agent of the present invention makes it possible to provide a photo-aligning liquid crystal alignment layer which can decrease storage of residual DC and shorten a relaxation time and which can prevent afterimages from being generated. Further, capable of being provided is a liquid crystal display device which comprises the above liquid crystal alignment layer and which is excellent in display characteristics.