LIQUID CRYSTAL DISPLAY DEVICE AND METHOD FOR MANUFACTURING SAME

Abstract

The present invention relates to a liquid crystal display element including a pair of a substrate arranged opposite to each other, an electrode group disposed on one side or both sides of the pair of substrates facing each other, a plurality of active elements connected to the electrode group, a liquid crystal alignment film disposed on each facing side of the pair of substrates, and a liquid crystal layer interposed between the pair of substrates, wherein the liquid crystal alignment film is manufactured by irradiating linearly polarized light to a film obtained from polyamic acid or a derivative thereof having a photoisomerization structure in the main chain or a film being subject to heat-baking so as to provide alignment-controlling capability, and the liquid crystal layer is a liquid crystal composition having negative () dielectric anisotropy. By the present invention, a liquid crystal display element having improved image sticking characteristics and good alignment stability is provided.

Claims

1. A liquid crystal display device, comprising a pair of substrates arranged opposite to each other, an electrode group disposed on one side or both sides of the pair of substrates facing each other, a plurality of active devices connected to the electrode group, a liquid crystal alignment film disposed on each facing side of the pair of substrates, and a liquid crystal layer interposed between the pair of substrates, wherein the liquid crystal alignment film is manufactured by irradiating linearly polarized light to a film obtained from polyamic acid or a derivative thereof having a photoisomerization structure in the main chain or a film being subject to heat-baking so as to provide alignment-controlling capability, and the liquid crystal layer comprises a liquid crystal composition having negative dielectric anisotropy and including at least one liquid crystal compound selected from the group of liquid crystal compounds of Formula (1-3), Formula (1-7), Formula (1-11), Formula (1-14), Formula (1-15), Formula (1-17), Formula (1-18), Formula (1-28), and Formula (1-32) as a first component: ##STR00120## wherein R.sup.1 and R.sup.2 are independently alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons, or alkenyl having 2 to 12 carbons, where arbitrary hydrogen is replaced by fluorine;

2. The liquid crystal display device of claim 1, wherein the liquid crystal composition having negative dielectric anisotropy comprises at least one selected from the group of liquid crystal compounds of Formula (1-7) and Formula (1-32) as a first component: ##STR00121## wherein R.sup.1 and R.sup.2 are independently alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons, or alkenyl having 2 to 12 carbons where arbitrary hydrogen is replaced by fluorine.

3. The liquid crystal display device of claim 1, wherein an electric field applied to a liquid crystal layer has a component parallel to the surface of the substrate.

4. The liquid crystal display device of claim 1, wherein the polyamic acid or the derivative thereof having a photoisomerization structure is polyamic acid or a derivative thereof obtained by reacting at least one of a tetracarboxylic dianhydride or a diamine having a photoisomerization structure selected from the following Formulae (I) to (VII):
[Formula 2]
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.1CHCHR.sup.3(V)
R.sup.2CHCHR.sup.3(VI)
R.sup.2NNR.sup.3(VII) wherein, in Formulae (I) to (VII), R.sup.2 and R.sup.3 are independently a monovalent organic group having NH.sub.2 or COOCO, and R.sup.4 is a divalent organic group including an aromatic ring.

5. The liquid crystal display device of claim 4, wherein the tetracarboxylic dianhydride having the photoisomerization structure is at least one selected from the following Formula (PAN-1) and Formula (PAN-2): ##STR00122##

6. The liquid crystal display device of claim 4, wherein the diamine having the photoisomerization structure is at least one selected from the following Formula (PDI-1) to Formula (PDI-8): ##STR00123## wherein, in Formula (PDI-1) to Formula (PDI-8), as for a group of which a bonding position is not fixed to any one of carbon atoms constituting a ring, the bonding position is arbitrary, in Formula (PDI-7), R.sup.5 is independently CH.sub.3, OCH.sub.3, CF.sub.3, or COOCH.sub.3, and b is an integer of 0 to 2.

7. The liquid crystal display device of claim 6, wherein the diamine having the photoisomerization structure is at least one selected from the following Formula (PDI-6-1) and Formula (PDI-7-1): ##STR00124##

8. The liquid crystal display device of claim 4, which comprises at least one of the group of a tetracarboxylic dianhydride represented by the following Formula (AN-I) to Formula (AN-VII), as a tetracarboxylic dianhydride in addition to the tetracarboxylic dianhydride having the photoisomerization structure: ##STR00125## wherein, in Formula (AN-I), Formula (AN-IV), and Formula (AN-V), X is independently a single bond or CH.sub.2; in Formula (AN-II), G is a single bond, alkylene having 1 to 20 carbons, CO, O, S, SO.sub.2, C(CH.sub.3).sub.2, or C(CF.sub.3).sub.2; and in Formula (AN-II) to Formula (AN-IV), Y is independently one selected from the group of the following trivalent groups: ##STR00126## wherein arbitrary hydrogen of the groups is optionally replaced by methyl, ethyl, or phenyl; in Formula (AN-Ill) to Formula (AN-V), ring A is a monocyclic hydrocarbon group having 3 to 10 carbons or a condensed polycyclic hydrocarbon group having 6 to 10 carbons, wherein arbitrary hydrogen of the groups is optionally replaced by methyl, ethyl, or phenyl, a bond bound to the ring is bound to arbitrary carbon constituting the ring, or two bonds is optionally bound to the same carbon; in Formula (AN-VI), X.sup.10 is alkylene having 2 to 6 carbons; Me is methyl; Ph is phenyl; in Formula (AN-VII), G.sup.10 is independently O, COO, or OCO; and r is independently 0 or 1.

9. The liquid crystal display device of claim 8, wherein the tetracarboxylic dianhydride in addition to the tetracarboxylic dianhydride having the photoisomerization structure comprises at least one selected from the group of the following Formula (AN-1-1), Formula (AN-1-13), Formula (AN-2-1), Formula (AN-3-1), Formula (AN-3-2), Formula (AN-4-5), Formula (AN-4-17), Formula (AN-4-21), Formula (AN-4-28), Formula (AN-4-29), Formula (AN-7-2), Formula (AN-10), and Formula (AN-11-3): ##STR00127## ##STR00128## wherein, in Formula (AN-4-17), m is an integer of 1 to 12.

10. The liquid crystal display device of claim 4, which comprises at least one selected from the group of the following Formula (DI-1) to Formula (DI-15), as a diamine in addition to the diamine having the photoisomerization structure selected from Formula (I) to Formula (VII): ##STR00129## wherein, in Formula (DI-1), m is an integer of 1 to 12; in Formula (DI-3) and Formula (DI-5) to Formula (DI-7), G.sup.21 is independently a single bond, NH, O, S, SS, SO.sub.2, CO, CONH, CONCH.sub.3, 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)(CH.sub.2).sub.kN(CH.sub.3), or S(CH.sub.2).sub.mS, m is independently an integer of 1 to 12, and k is an integer of 1 to 5; in Formula (DI-6) and Formula (DI-7), G.sup.22 is 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 carbons; arbitrary H of a cyclohexane ring and a benzene ring of Formula (DI-2) to Formula (DI-7) is optionally replaced by F, CH.sub.3, OH, CF.sub.3, CO.sub.2H, CO.sub.2H, CONH.sub.2, or benzyl, or that in Formula (DI-4) is optionally replaced by the following Formula (DI-4-a) to Formula (DI-4-c): ##STR00130## wherein, in Formula (DI-4-a) and Formula (DI-4-b), R.sup.20 is independently H or CH.sub.3; in Formula (DI-2)-Formula (DI-7), as for a group of which a bonding position is not fixed to any one of carbon atoms constituting a ring, the bonding position is arbitrary; and a bonding position of NH.sub.2 bound to the cyclohexane ring or benzene ring is arbitrary except a bonding position of G.sup.21 or G.sup.22, ##STR00131## wherein, in Formula (DI-8), R.sup.21 and R.sup.22 are independently alkyl having 1 to 3 carbons or phenyl; G.sup.23 is independently C1-C6 alkylene, phenylene, or alkyl-substituted phenylene; n is an integer of 1-10; in Formula (DI-9), R.sup.23 is independently alkyl having 1 to 5 carbons, alkoxy having 1 to 5 carbons, or Cl; p is independently an integer of 1 to 3; q is an integer of 0 to 4; in Formula (DI-10), R.sup.24 is H, alkyl having 1 to 4 carbons, 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 carbons, or 1,4-phenylene; r is 0 or 1; in Formula (DI-12), as for a group of which a bonding position is not fixed to any one of carbon atoms constituting a ring, the bonding position is arbitrary; and in Formula (DI-9), Formula (DI-11), and Formula (DI-12), a bonding position of NH.sub.2 bound to the benzene ring is arbitrary, ##STR00132## wherein, in Formula (DI-13), G.sup.31 is a single bond, alkylene having 1 to 20 carbons, CO, O, S, SO.sub.2, C(CH.sub.3).sub.2, or C(CF.sub.3).sub.2; in Formula (DI-14), ring B is optionally a cyclohexane ring, a benzene ring, or a naphthalene ring, where arbitrary hydrogen of the rings is optionally replaced by methyl, ethyl, or phenyl; in Formula (DI-15), rings C are each independently a cyclohexane ring or a benzene ring, where arbitrary hydrogen of the rings is optionally replaced by methyl, ethyl, or phenyl; and Y is a single bond, alkylene having 1 to 20 carbons, CO, O, S, SO.sub.2, C(CH.sub.3).sub.2, or C(CF.sub.3).sub.2.

11. The liquid crystal display device of claim 10, wherein the diamine in addition to the diamine having the photoisomerization structure selected from Formula (I) to Formula (VII) comprises at least one selected from the group of the following Formula (DI-1-3), Formula (DI-1-4), Formula (DI-4-1), Formula (DI-5-1), Formula (DI-5-5), Formula (DI-5-9), Formula (DI-5-12), Formula (DI-5-21), Formula (DI-5-28), Formula (DI-5-30), Formula (DI-5-31), Formula (DI-7-3), Formula (DI-9-1), Formula (DI-13-1), Formula (DI-13-2), Formula (DI-14-1), or Formula (DI-14-2): ##STR00133## wherein in Formula (DI-5-1), Formula (DI-5-12), Formula (DI-7-3), and Formula (DI-13-2), 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 liquid crystal display device of claim 1, wherein the liquid crystal alignment film is formed by a liquid crystal alignment agent including the polyamic acid or the derivative thereof having a photoisomerization structure in the main chain, and other polymers.

13. The liquid crystal display device of claim 1, wherein the liquid crystal alignment film is formed of a liquid crystal alignment agent further comprising at least one selected from the group of compounds of an alkenyl-substituted nadimide compound, a compound having a radical-polymerizable unsaturated double bond, an oxazine compound, an oxazoline compound, and an epoxy compound.

14. The liquid crystal display device of claim 1, which is manufactured by applying a liquid crystal alignment agent on a substrate, heat-drying the substrate applied with the liquid crystal alignment agent, and irradiating linearly polarized light to provide alignment capability.

15. The liquid crystal display device of claim 1, which is manufactured by applying a liquid crystal alignment agent on a substrate, heat-drying the substrate applied with the liquid crystal alignment agent, irradiating linearly polarized light to provide alignment capability, and then heat-baking the resultant film.

16. The liquid crystal display device of claim 1, which is manufactured by applying a liquid crystal alignment agent on a substrate, heat-drying the substrate applied with the liquid crystal alignment agent, heat-baking the dried film, and irradiating linearly polarized light to provide alignment capability.

Description

EXAMPLES

[0315] Hereinafter, the present invention will be explained in more detail by way of examples, but the invention is not limited by the examples. Each evaluation method of a liquid crystal display device is as follows.

[0316] <Weight Average Molecular Weight (Mw)>

[0317] The weight average molecular weight of the polyamic acid was measured according to a GPC method using a 2695 separation module2414 differential refractometer (manufactured by Waters Corporation), and was calculated in terms of polystyrene. The obtained polyamic acid was diluted to be about 2 wt % of polyamic acid concentration with a phosphoric acid-DMF mixed solution (phosphoric acid/DMF=0.6/100 (weight ratio)). Measurement was carried out using HSPgel RT MB-M (manufactured by Waters Corporation) as a column, and the mixed solution as an eluent, under conditions of a column temperature of 50 C. and a flow rate of 0.40 mL/min. For standard polystyrene, TSK standard polystyrene manufactured by Tosoh Corporation was used.

[0318] <Evaluation Method of Liquid Crystal Display Device>

[0319] <1. Pretilt Angle>

[0320] A spectral ellipsometer M-2000U (manufactured by J. A. Woollam Co. Inc.) was used.

[0321] <2. AC Image Sticking (Brightness Change Rate)>

[0322] Brightness-voltage characteristics (B-V characteristics) of a post-described liquid crystal display device were measured. This value was regarded as brightness-voltage characteristics: B (before) before applying stress to the liquid crystal display device. Then, the brightness-voltage characteristics (B-V characteristics) were measured again after applying an alternating current at 4.5 V and 60 Hz for 20 minutes to the liquid crystal display device and short-circuiting it for 1 second. This value was regarded as brightness-voltage characteristics: B (after) after applying the stress. These values were used to obtain a brightness change rate B (%) by using the following equation.

B (%)=[B(after)B(before)]/B(before)(Equation 1)

[0323] These measurements were performed according to a pamphlet of International Publication No. 2000/43833. As the B (%) at a voltage of 0.75 V is smaller, an AC image sticking may be more prevented.

[0324] <3. Alignment Stability (Liquid Crystal Alignment Axis Stability)>

[0325] The change rate of a liquid crystal alignment axis at an electrode of the post-described liquid crystal display was obtained. An liquid crystal alignment angle (before) at the electrode before applying the stress was measured, and then, after applying a rectangular wave of 4.5 V, 60 Hz to the liquid crystal display for 20 minutes and short-circuiting it for one second, liquid crystal alignment angles (after) at the electrode were respectively measured again after 1 second and 5 minutes. Then, liquid crystal alignment angle changes (deg.) after one second and 5 minutes were obtained based on the above measurements according to the following equation.

T (deg.)=(after)(before)(Equation 2)

[0326] These measurements were performed referring to J. Hilfiker, B. Johs, C. Herzinger, J. F. Elman, E. Montbach, D. Bryant, and P. J. Bos Thin Solid Films, 455-456, 2004, 596-600. Herein, a small indicates a small change rate of a liquid crystal alignment axis and excellent stability of the liquid crystal alignment axis.

[0327] Solvents, additives, and liquid crystal compositions used in examples are as follows.

[0328] <Solvent>

[0329] N-methyl-2-pyrrolidone: NMP

[0330] Butyl cellosolve (ethylene glycol monobutylether): BC

[0331] <Additive>

[0332] Additive (Ad1): bis[4-(allylbicyclo[2.2.1]hepto-5-ene-2,3-dicarboxylimide)phenyl]methane

[0333] Additive (Ad2): N,N,N,N-tetraglycidyl-4,4-diaminodiphenylmethane

[0334] Additive (Ad3): 3-aminopropyltriethoxysilane

[0335] Additive (Ad4): 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane

[0336] <Liquid Crystal Composition>

[0337] Positive Liquid Crystal Composition:

##STR00113##

[0338] Negative Liquid Crystal Composition A:

##STR00114##

[0339] Negative Liquid Crystal Composition B:

##STR00115##

[0340] Negative Liquid Crystal Composition C:

##STR00116##

[0341] Negative Liquid Crystal Composition D:

##STR00117## ##STR00118##

[0342] Negative Liquid Crystal Composition E:

##STR00119##

[0343] <1. Synthesis of Polyamic Acid of [A]>

Synthesis Example 1

[0344] 0.2102 g of diamine (DI-5-1, m=2), 0.0664 g of diamine (DI-9-1), 0.2082 g of diamine (PDI-6-1), 0.5778 g of diamine (PDI-7-1), and 18.5 g 50 mL of dehydration NMP were put in a brown four-necked flask equipped with a thermometer, a stirrer, an inlet for feeding a raw material, and another inlet for introducing nitrogen gas and then stirred and dissolved under a dry nitrogen stream. Subsequently, 0.1268 g of acid dianhydride (AN-1-13), 1.8106 g of acid dianhydride (AN-4-17, m=8), and 18.5 g of dehydrated NMP were added thereto and continuously stirred at room temperature for 24 hours. Then, 10.0 g of BC was added to the reaction solution, obtaining a polyamic acid solution having a polymer solid concentration of 6 wt %. This polyamic acid solution is called PA1. A weight average molecular weight of the polyamic acid included in the PA1 was 39,400.

Synthesis Examples 2 to 8

[0345] As shown in Table 1, polyamic acid solutions PA2 to PA8 respectively having a polymer solid concentration of 6 wt % were prepared according to the same method as Synthesis Example 1, except for changing the tetracarboxylic dianhydride and the diamine. Table 1 shows the weight average molecular weight results of the obtained polyamic acids as well as the result of Synthesis Example 1.

TABLE-US-00001 TABLE 1 Weight Synthesis Polyamic Tetracarboxylic average Ex. acid dianhydride Diamine molecular No. No. (mol %)) (mol %) weight 1 PA1 AN-1-13 (10) DI-5-1 (m = 2) (20) 39,400 AN-4-17 (m = 8) (90) DI-9-1 (5) PDI-6-1 (20) PDI-7-1 (55) 2 PA2 AN-3-1 (30) DI-5-1 (m = 2) (50) 42,000 AN-4-17 (m = 8) (70) PDI-7-1 (50) 3 PA3 AN-4-17 (m = 8) (100) DI-5-1 (m = 4) (40) 32,000 PDI-7-1 (60) 4 PA4 AN-4-21 (100) DI-5-1 (m = 4) (25) 21,700 PDI-7-1 (75) 5 PA5 AN-4-21 (100) DI-5-4 (50) 28,600 PDI-7-1 (50) 6 PA6 PAN-2 (100) DI-2-1 (20) 40,700 PDI-7-1 (80) 7 PA7 AN-4-17 (m = 8) (100) DI-19-7 (R.sup.41C.sub.7H.sub.15) (3) 17,500 PDI-7-1 (97) 8 PA8 AN-4-17 (m = 8) (100) DI-4-13 (10) 15,200 DI-16-5 (R.sup.35C.sub.5H.sub.11) (5) PDI-7-1 (85)

[0346] <2. Synthesis of Polyamic Acid of [B]>

Synthesis Example 9

[0347] 0.7349 g of diamine (DI-4-1) and 18.5 g of dehydration NMP were put in a brown 50 mL four-necked flask equipped with a thermometer, a stirrer for feeding a raw material, and another inlet for introducing nitrogen gas and then stirred and dissolved under a dry nitrogen stream. Subsequently, 0.6732 g of acid dianhydride (AN-1-1), 1.5918 g of acid dianhydride (AN-4-28), and 18.5 g of dehydrated NMP were added thereto at room temperature and continuously stirred for 24 hours. Then, 10.0 g of BC was added to the reaction solution, obtaining a polyamic acid solution having a polymer solid concentration of 6 wt %. This polyamic acid solution was called PA9. A weight average molecular weight of the polyamic acid included in the PA9 was 51,000.

Synthesis Examples 10 to 24

[0348] As shown in Table 2, polyamic acid solutions (PA10) to (PA24) respectively having a polymer solid concentration of 6 wt % were prepared according to the same method as Synthesis Example 9, except for changing the tetracarboxylic dianhydride and the diamine. Table 2 shows the weight average molecular weight results of the obtained polyamic acids as well as the result of Synthesis Example 9.

TABLE-US-00002 TABLE 2 Syn- Poly- Weight thesis amic Tetracarboxylic average Ex. acid dianhydride molecular No. No. (mol %) Diamine (mol %) weight 9 PA9 AN-1-1 (50) DI-4-1 (100) 51,000 AN-4-28 (50) 10 PA10 AN-1-1 (5) DI-5-1 (m = 1) (90) 79,200 AN-2-1 (95) DI-5-4 (10) 11 PA11 AN-1-1 (5) DI-5-1 (m = 8) (100) 72,200 AN-2-1 (95) 12 PA12 AN-1-13 (40) DI-5-1 (m = 4) (100) 84,000 AN-3-2 (60) 13 PA13 AN-1-13 (40) DI-5-1 (m = 4) (80) 71,100 AN-3-2 (40) DI-14-1 (20) AN-4-28 (20) 14 PA14 AN-1-13 (20) DI-4-1 (100) 100,600 AN-4-28 (80) 15 PA15 AN-2-1 (100) DI-2-1 (50) 90,200 DI-9-1 (50) 16 PA16 AN-2-1 (100) DI-4-1 (100) 86,400 17 PA17 AN-2-1 (100) DI-5-1 (m = 1) (80) 90,800 DI-9-1 (20) 18 PA18 AN-2-1 (80) DI-5-1 (m = 1) (100) 69,900 AN-3-1 (20) 19 PA19 AN-2-1 (70) DI-5-1 (m = 1) (80) 74,000 AN-3-2 (30) DI-9-1 (20) 20 PA20 AN-2-1 (100) DI-5-1 (m = 2) (80) 90,500 DI-5-30 (20) 21 PA21 AN-3-1 (10) DI-4-1 (100) 68,600 AN-3-2 (50) AN-4-28 (40) 22 PA22 AN-3-1 (100) DI-1-3 (100) 101,000 23 PA23 AN-4-5 (100) DI-1-3 (100) 75,200 24 PA24 AN-2-1 (50) DI-4-1 (100) 76,000 AN-3-2 (50)

[0349] The polyamic acid PA1 of Synthesis Example 1 as a polymer [A] and the polyamic acid PA9 of Synthesis Example 9 as a polymer [B] were mixed in a weight ratio of [A]/[B]=3.0/7.0, and the mixture was called PA25. The polyamic acid solutions (PA26) to (PA43) were prepared to have a polymer solid concentration of 6 wt % according to the same method as PA25 except for changing a kind of polyamic acid as [A] and [B] components and a weight ratio of [A]/[13]. Table 3 shows a kind of polyamic acid as [A] and [B] components and a weight ratio of [A]/[13] as well as those in the PA25.

TABLE-US-00003 TABLE 3 Polyamic acid Polyamic acid Polyamic No. of [A] No. of [B] [A]/[B] mixing ratio acid No. component component (weight ratio) PA25 PA1 PA9 3.0/7.0 PA26 PA2 PA10 3.0/7.0 PA27 PA2 PA11 3.0/7.0 PA28 PA2 PA12 3.0/7.0 PA29 PA3 PA13 3.0/7.0 PA30 PA3 PA14 2.0/8.0 PA31 PA4 PA15 2.0/8.0 PA32 PA4 PA16 2.0/8.0 PA33 PA5 PA17 3.0/7.0 PA34 PA5 PA18 3.0/7.0 PA35 PA6 PA19 3.0/7.0 PA36 PA3 PA20 3.0/7.0 PA37 PA3 PA21 3.0/7.0 PA38 PA4 PA22 2.5/7.5 PA39 PA4 PA23 2.5/7.5 PA40 PA7 PA12 3.0/7.0 PA41 PA7 PA24 3.0/7.0 PA42 PA8 PA19 3.0/7.0 PA43 PA8 PA24 3.0/7.0

[0350] As shown Table 4, 5 wt % of an additive (Ad1) per a weight (100 wt %) of a polymer was added to the polyamic acid solution (PA3) having a polymer solid concentration of 6 wt % according to Synthesis Example 3. The obtained polyamic acid solution was called PA44.

[0351] As shown in Table 4, polyamic acid solutions (PA45) to (PA48) were prepared by adding additives (Ad2) to (Ad4) in a ratio shown in Table 4.

TABLE-US-00004 TABLE 4 Polyamic Polyamic Addition acid No. acid solution Additive amount (wt %) PA44 PA3 Ad1 5 PA45 PA30 Ad2 5 PA46 PA35 Ad3 4 PA47 PA37 Ad4 3 PA48 PA41 Ad4 0.5

Comparative Synthesis Example 1

[0352] 2.1325 g of diamine (DI-4-1) and 74 g of dehydration NMP were put in a 100 mL brown four-necked flask equipped with a thermometer, a stirrer, an inlet for feeding a raw material, and another inlet for introducing nitrogen gas and then stirred and dissolved under a dry nitrogen stream. Subsequently, 3.8675 g of acid dianhydride (AN-2-1) and 20.0 g of BC were added thereto, and the mixture was stirred at room temperature for 24 hours, obtaining a polyamic acid solution having a polymer solid concentration of 6 wt %. This polyamic acid solution was called PA49. A weight average molecular weight of the polyamic acid included in the PA49 was 120,500.

[0353] <2. Manufacture of Liquid Crystal Display Device>

Example 1

[0354] <Method of Manufacturing Liquid Crystal Display Device>

[0355] A mixed solvent of NMP/BC=4/1 (weight ratio) was added to the polyamic acid solution (PA1) having a polymer solid content of 6 wt % prepared in Synthesis Example 1, and the polymer solid content was diluted to 4 wt % to prepare a liquid crystal alignment agent. The liquid crystal alignment agent was applied to a glass substrate with column spacers and a glass substrate with an ITO electrode using a spinner (manufactured by Mikasa Co., Ltd., spin coater (1H-DX2)). A rotation speed of the spinner was controlled depending on viscosity of the liquid crystal alignment agent and an alignment film having the following film thickness was formed, which are the same in the following examples and comparative examples. The formed polyamic acid solution film was heat-dried on a hot plate (manufactured by AS ONE Corporation, EC hot plate (EC-1200N)) at 70 C. for 80 seconds. Subsequently, ultraviolet (UV) linearly polarized light was irradiated through a polarizer using Multi Light ML-501C/B manufactured by Ushio, Inc. in a perpendicular direction with respect to the substrate. Herein, a dose of exposure energy was measured using an ultraviolet (UV) integral actinometer UIT-150 (light receiver UVD-5365) manufactured by Ushio, Inc., and an exposure time was controlled so that the dose might be 2.00.1 J/cm.sup.2 at a wavelength of 365 nm. Then, the resultant was heat-treated at 230 C. for 15 minutes in a clean oven (manufactured by Espec Corp., clean oven (PVHC-231)) to manufacture an alignment film having a film thickness of 10010 nm.

[0356] The two substrates on which each alignment film was formed were bonded to each other so that the alignment films might be opposed to each other and polarization directions of ultraviolet (UV) light irradiated to each alignment film were parallel to each other, and a gap for injecting a liquid crystal composition between the opposed alignment films might be formed, to assemble a vacant FFS cell having a cell thickness of 4 m. A injection hole for injecting liquid crystals into the vacant FFS cell was formed at the position where a flow direction of the liquid crystals during injection was approximately parallel to the polarization direction of the ultraviolet (UV) light irradiated to the alignment film. The negative liquid crystal composition A was vacuum-injected into the vacant FFS cell to manufacture a liquid crystal display device.

[0357] A pretilt angle of the manufactured FFS liquid crystal display device was measured according to the above method, and was 0.0. In addition, flow alignment was not shown, and alignment properties were good.

[0358] A brightness change rate B (%) of the manufactured FFS liquid crystal display device was measured according to the above method, and was 5.2%.

[0359] Liquid crystal alignment axis stability (deg.) of the manufactured FFS liquid crystal display device was measured according to the above method, and the initial value was 0.024 deg., while the value after 5 minutes was 0.017 deg.

Examples 2 to 21

[0360] A mixed solvent of NMP/BC=4/1 (weight ratio) was added to the polyamic acid solutions PA2, PA25-PA39, and PA44-PA47 having each polymer solid content of 6 wt %, and the polymer solid content was diluted to 4 wt % to prepare each liquid crystal alignment agent. Each FFS liquid crystal display device was manufactured using each liquid crystal alignment agent according to the same method as in Example 1, and the negative liquid crystal composition was injected. Pretilt angles, brightness change rates B (%), and liquid crystal alignment axis stability (deg.) of the obtained FFS liquid crystal display devices were measured. The results are shown in Table 5 with the results of Example 1.

Comparative Examples 1 and 2

[0361] A mixed solvent of NMP/BC=4/1 (weight ratio) was added to the polyamic acid solutions PA1 or PA25 having each polymer solid content of 6 wt %, and the polymer solid content was diluted to 4 wt % to prepare each liquid crystal alignment agent. Each FFS liquid crystal display device was manufactured using each liquid crystal alignment agent according to the same method as in Example 1, and the positive liquid crystal composition was injected. Pretilt angles, brightness change rates B (%), and liquid crystal alignment axis stability (deg.) of the obtained FFS liquid crystal display devices were measured. The results are shown in Table 5 with the results of Examples 1 to 21.

Comparative Examples 3 and 4

[0362] A mixed solvent of NMP/BC=4/1 (weight ratio) was added to the polyamic acid solution PA49 having a polymer solid content of 6 wt %, and the polymer solid content was diluted to 4 wt % to prepare a liquid crystal alignment agent. The liquid crystal alignment agent was applied on a substrate to form a film, and was heat-dried at 70 C. for 80 seconds. Subsequently, the resultant was heat-treated at 230 C. for 15 minutes to form an alignment film having a film thickness of 10010 nm. Then, ultraviolet (UV) linearly polarized light was irradiated through a polarizer using Multi Light ML-501C/B manufactured by Ushio, Inc. in a perpendicular direction with respect to the substrate. Herein, a dose of exposure energy was measured using an ultraviolet (UV) integral actinometer UIT-150 (a light receiver UVD-S365) manufactured by Ushio, Inc., and an exposure time was controlled so that the dose might be 2.00.1 J/cm.sup.2 at a wavelength of 365 nm. FFS liquid crystal display devices were manufactured using the liquid crystal alignment agent according to the same method as in Example 1, and each of the positive liquid crystal composition and the negative liquid crystal composition A were injected.

[0363] Pretilt angles, brightness change rates B (%), and liquid crystal alignment axis stability (deg.) of the obtained FFS liquid crystal display devices were measured. The results are shown in Table 5 with the results of Examples 1 to 21 and Comparative Examples 1 and 2.

Example 22

[0364] A mixed solvent of NMP/BC=4/1 (weight ratio) was added to the polyamic acid solution (PA27) having a polymer solid content of 6 wt %, and the polymer solid content was diluted to 4 wt % to prepare a liquid crystal alignment agent. The liquid crystal alignment agent was applied to a glass substrate using a spinner (manufactured by Mikasa Co., Ltd., spin coater (1H-DX2)). The formed polyamic acid solution film was heat-dried on a hot plate (manufactured by AS ONE Corporation, EC hot plate (EC-1200N)) at 70 C. for 80 seconds, and ultraviolet (UV) linearly polarized light was irradiated through a polarizer using Multi Light ML-501C/B manufactured by Ushio, Inc. in a perpendicular direction with respect to the substrate. Herein, a dose of exposure energy was measured using an ultraviolet (UV) integral actinometer UIT-150 (a light receiver UVD-S365) manufactured by Ushio, Inc., and an exposure time was controlled so that the dose might be 0.70.1 J/cm.sup.2 at a wavelength of 365 nm. During ultraviolet (UV) light exposure, the substrate was heated at a temperature of 50 C. The irradiation of the ultraviolet (UV) light was performed while covering the whole device with an ultraviolet (UV) blocking film at room temperature under air. Then, the resultant was heat-treated at 230 C. for 15 minutes in a clean oven (manufactured by Espec Corp., clean oven (PVHC-231)) to manufacture an alignment film having a film thickness of 10010 nm.

[0365] The two substrates on which each alignment film was formed were bonded to each other so that the alignment films might be opposed to each other and polarization directions of ultraviolet (UV) light irradiated to each alignment film were parallel to each other, and a gap for injecting a liquid crystal composition between the opposed alignment films might be formed, to assemble a vacant FFS cell having a cell thickness of 4 m. A injection hole for injecting liquid crystals into the vacant FFS cell was formed at the position where a flow direction of the liquid crystals during injection was approximately parallel to the polarization direction of the ultraviolet (UV) light irradiated to the alignment film. The negative liquid crystal composition B was vacuum-injected into the vacant FFS cell to manufacture a liquid crystal display device.

[0366] A pretilt angle of the manufactured FFS liquid crystal display device was measured according to the above method, and was 0.0. In addition, flow alignment was not shown, and alignment properties were good.

[0367] A brightness change rate B (%) of the manufactured FFS liquid crystal display device was measured according to the above method, and was 2.1%.

[0368] Liquid crystal alignment axis stability (deg.) of the manufactured FFS liquid crystal display device was measured according to the above method, and the initial value was 0.019 deg., while the value after 5 minutes was 0.010 deg.

Examples 23 to 25

[0369] A mixed solvent of NMP/BC=4/1 (weight ratio) was added to the polyamic acid solutions (PA40, PA42, and PA48) having each polymer solid content of 6 wt %, and the polymer solid content was diluted to 4 wt % to prepare each liquid crystal alignment agent. Liquid crystal display devices were manufactured using the obtained liquid crystal alignment agents according to the same method as in Example 22. The result of pretilt angles, brightness change rates B (%), and liquid crystal alignment axis stability (deg.) of the obtained FFS liquid crystal display devices were shown in Table 5 with the results of Example 22.

Example 26

[0370] A mixed solvent of NMP/BC=4/1 (weight ratio) was added to the polyamic acid solution (PA34) having a polymer solid content of 6 wt %, and the polymer solid content was diluted to 4 wt % to prepare a liquid crystal alignment agent. The liquid crystal alignment agent was applied to a glass substrate using a spinner (manufactured by Mikasa Co., Ltd., spin coater (1H-DX2)). The formed polyamic acid solution film was heat-dried on a hot plate (manufactured by AS ONE Corporation, EC hot plate (EC-1200N)) at 70 C. for 80 seconds, and ultraviolet (UV) linearly polarized light was irradiated through a polarizer using Multi Light ML-501C/B manufactured by Ushio, Inc. in a perpendicular direction with respect to the substrate. Herein, a dose of exposure energy was measured using an ultraviolet (UV) integral actinometer UIT-150 (light receiver UVD-S365) manufactured by Ushio, Inc., and an exposure time was controlled so that the dose might be 1.00.1 J/cm.sup.2 at a wavelength of 365 nm. The irradiation of the ultraviolet (UV) light was performed while covering the whole device with an ultraviolet (UV) blocking film at room temperature under air. Then, the resultant was heat-treated at 230 C. for 15 minutes in a clean oven (manufactured by Espec Corp., clean oven (PVHC-231)) to manufacture an alignment film having a film thickness of 10010 nm.

[0371] The two substrates on which each alignment film was formed were bonded to each other so that the alignment films might be opposed to each other and polarization directions of ultraviolet (UV) light irradiated to each alignment film were parallel to each other, and a gap for injecting a liquid crystal composition between the opposed alignment films might be formed, to assemble a vacant FFS cell having a cell thickness of 4 m. A injection hole for injecting liquid crystals into the vacant FFS cell was formed at the position where a flow direction of the liquid crystals during injection was approximately parallel to the polarization direction of the ultraviolet (UV) light irradiated to the alignment film. The negative liquid crystal composition B was vacuum-injected into the vacant FFS cell to manufacture a liquid crystal display device.

[0372] A pretilt angle of the manufactured FFS liquid crystal display device was measured according to the above method, and was 0.0. In addition, flow alignment was not shown, and alignment properties were good.

[0373] A brightness change rate B (%) of the manufactured FFS liquid crystal display device was measured according to the above method, and was 2.3%.

[0374] Liquid crystal alignment axis stability (deg.) of the manufactured FFS liquid crystal display device was measured according to the above method, and the initial value was 0.013 deg., while the value after 5 minutes was 0.010 deg.

Examples 27 and 28

[0375] A mixed solvent of NMP/BC=4/1 (weight ratio) was added to the polyamic acid solutions (PA41 and PA43) having a polymer solid content of 6 wt %, and the polymer solid content was diluted to 4 wt % to prepare each liquid crystal alignment agent. Each FFS liquid crystal display device was manufactured using each liquid crystal alignment agent according to the same method as in Example 26. The results are shown in Table 5 with the results of Example 26.

Example 29

[0376] A mixed solvent of NMP/BC=4/1 (weight ratio) was added to the polyamic acid solution (PA33) having a polymer solid content of 6 wt %, and the polymer solid content was diluted to 4 wt % to prepare a liquid crystal alignment agent. The liquid crystal alignment agent was applied to a glass substrate with column spacers and a glass substrate with an ITO electrode using a spinner (manufactured by Mikasa Co., Ltd., spin coater (1H-DX2)). A rotation speed of the spinner was controlled depending on viscosity of the liquid crystal alignment agent and an alignment film having the following film thickness was formed, which are the same in the following examples and comparative examples. The formed polyamic acid solution film was heat-dried on a hot plate (manufactured by AS ONE Corporation, EC hot plate (EC-1200N)) at 70 C. for 80 seconds. Subsequently, ultraviolet (UV) linearly polarized light was irradiated through a polarizer using Multi Light ML-501C/B manufactured by Ushio, Inc. in a perpendicular direction with respect to the substrate. Herein, a dose of exposure energy was measured using an ultraviolet (UV) integral actinometer UIT-150 (light receiver UVD-5365) manufactured by Ushio, Inc., and an exposure time was controlled so that the dose might be 2.00.1 J/cm.sup.2 at a wavelength of 365 nm. Then, the resultant was heat-treated at 230 C. for 15 minutes in a clean oven (manufactured by Espec Corp., clean oven (PVHC-231)) to manufacture an alignment film having a film thickness of 10010 nm.

[0377] The two substrates on which each alignment film was formed were bonded to each other so that the alignment films might be opposed to each other and polarization directions of ultraviolet (UV) light irradiated to each alignment film were parallel to each other, and a gap for injecting a liquid crystal composition between the opposed alignment films might be formed, to assemble a vacant FFS cell having a cell thickness of 4 m. A injection hole for injecting liquid crystals into the vacant FFS cell was formed at the position where a flow direction of the liquid crystals during injection was approximately parallel to the polarization direction of the ultraviolet (UV) light irradiated to the alignment film. The negative liquid crystal composition C was vacuum-injected into the vacant FFS cell to manufacture a liquid crystal display device.

[0378] A pretilt angle of the manufactured FFS liquid crystal display device was measured according to the above method, and was 0.0. In addition, flow alignment was not shown, and alignment properties were good.

[0379] A brightness change rate B (%) of the manufactured FFS liquid crystal display device was measured according to the above method, and was 5.2%.

[0380] Liquid crystal alignment axis stability (deg.) of the manufactured FFS liquid crystal display device was measured according to the above method, and the initial value was 0.024 deg., while the value after 5 minutes was 0.017 deg.

Examples 30 to 34

[0381] A mixed solvent of NMP/BC=4/1 (weight ratio) was added to the polyamic acid solutions PA41, PA44, PA41, PA33, and PA43 having each polymer solid content of 6 wt %, and the polymer solid content was diluted to 4 wt % to prepare each liquid crystal alignment agent. Each FFS liquid crystal display device was manufactured using each liquid crystal alignment agent according to the same method as in Example 1, and the negative liquid crystal composition was injected. Pretilt angles, brightness change rates B (%), and liquid crystal alignment axis stability (deg.) of the obtained FFS liquid crystal display devices were measured. The results are shown in Table 5 with the results of Example 1.

TABLE-US-00005 TABLE 5 Liquid crystal AC alignment axis Pretilt Flow image stability (deg) Example Varnish Liquid angle alignment sticking After 5 Nos. Nos. crystal (deg) (Yes No) B (%) Initial min. Ex. 1 PA1 Negative A 0.0 No 5.2 0.024 0.017 Ex. 2 PA2 Negative A 0.0 No 4.8 0.024 0.013 Ex. 3 PA25 Negative A 0.0 No 2.8 0.021 0.010 Ex. 4 PA26 Negative A 0.0 No 1.7 0.019 0.011 Ex. 5 PA27 Negative A 0.0 No 3.5 0.023 0.013 Ex. 6 PA28 Negative A 0.0 No 1.6 0.013 0.008 Ex. 7 PA29 Negative A 0.0 No 1.6 0.015 0.009 Ex. 8 PA30 Negative A 0.0 No 2.0 0.022 0.010 Ex. 9 PA31 Negative A 0.0 No 2.4 0.027 0.015 Ex. 10 PA32 Negative A 0.0 No 2.8 0.024 0.011 Ex. 11 PA33 Negative A 0.0 No 3.1 0.025 0.013 Ex. 12 PA34 Negative A 0.0 No 2.5 0.011 0.010 Ex. 13 PA35 Negative A 0.0 No 1.8 0.014 0.009 Ex. 14 PA36 Negative A 0.0 No 2.2 0.016 0.014 Ex. 15 PA37 Negative A 0.0 No 1.5 0.017 0.010 Ex. 16 PA38 Negative A 0.0 No 1.3 0.019 0.011 Ex. 17 PA39 Negative A 0.0 No 1.5 0.020 0.011 Ex. 18 PA44 Negative A 0.0 No 5.0 0.023 0.015 Ex. 19 PA45 Negative A 0.0 No 2.0 0.021 0.010 Ex. 20 PA46 Negative A 0.0 No 1.5 0.015 0.009 Ex. 21 PA47 Negative A 0.0 No 1.5 0.016 0.010 Ex. 22 PA27 Negative B 0.0 No 2.1 0.019 0.010 Ex. 23 PA40 Negative B 0.0 No 1.2 0.015 0.009 Ex. 24 PA42 Negative B 0.0 No 1.1 0.015 0.008 Ex. 25 PA48 Negative B 0.0 No 1.5 0.018 0.011 Ex. 26 PA34 Negative B 0.0 No 2.3 0.013 0.010 Ex. 27 PA41 Negative B 0.0 No 1.4 0.020 0.011 Ex. 28 PA43 Negative B 0.0 No 1.0 0.014 0.009 Ex. 29 PA33 Negative C 0.0 No 2.5 0.021 0.013 Ex. 30 PA41 Negative C 0.0 No 2.0 0.026 0.013 Ex. 31 PA44 Negative D 0.0 No 3.1 0.019 0.01 Ex. 32 PA41 Negative D 0.0 No 1.6 0.019 0.009 Ex. 33 PA33 Negative E 0.0 No 2.3 0.021 0.014 Ex. 34 PA43 Negative E 0.0 No 1.1 0.015 0.008 Comp. PA1 Positive 0.0 No 8.0 0.039 0.022 Ex. 1 Comp. PA25 Positive 0.0 No 5.2 0.035 0.020 Ex. 2 Comp. PA49 Positive 0.0 No 12.3 0.090 0.041 Ex. 3 Comp. PA49 Negative A 0.0 No 9.1 0.063 0.046 Ex. 4

[0382] Comparing Examples 1 to 34 with Comparative Examples 1 to 4, the liquid crystal display device of the present invention reduced an AC image sticking and thus showed high liquid crystal alignment axis stability.

INDUSTRIAL APPLICABILITY

[0383] The present invention may provide a liquid crystal display having improved image sticking characteristics and excellent alignment stability by using an alignment film including polyamic acid or a derivative thereof having a photoisomerization structure in the main chain and a liquid crystal molecule having negative dielectric anisotropy.