Liquid crystal alignment composition, method of preparing liquid crystal alignment film, and liquid crystal alignment film, and liquid crystal display using the same

A liquid crystal alignment composition comprising

• a first liquid crystal alignment polymer comprising at least one repeat unit selected from a repeat unit represented by Chemical Formula 1, a repeat unit represented by Chemical Formula 2, or a repeat unit represented by Chemical Formula 3;
• a second liquid crystal alignment polymer comprising at least one repeat unit selected from a repeat unit represented by Chemical Formula 4, a repeat unit represented by Chemical Formula 5, or repeat units represented by Chemical Formula 6;
• a third liquid crystal alignment polymer comprising at least one repeat unit selected from a repeat unit represented by Chemical Formula 7, a repeat unit represented by Chemical Formula 8, or a repeat unit represented by Chemical Formula 9;
• and
• a cross-linking agent compound represented by Chemical Formula 16:
• in the Chemical Formulae 1 to 9,
• at least one of R1 and R2 is a C1-10 alkyl group, and the other is hydrogen,
• at least one of R3 and R4 is a C1-10 alkyl group, and the other is hydrogen,
• at least one of R5 and R6 is a C1-10 alkyl group, and the other is hydrogen,
• X1 to X9 are each independently, a tetravalent organic group represented by Chemical Formula 10,
• in the Chemical Formula 10,
• R7 to R12 are each independently, hydrogen, or a C1-6 alkyl group,
• L1 is a single bond, —O—, —CO—, —COO—, —S—, —SO—, —SO2—, —CR13R14—, —(CH2)Z—, —O(CH2)ZO—, —COO(CH2)ZOCO—, —CONH—, phenylene, or a combination thereof, wherein R13 and R14 are each independently, hydrogen, a C1-10 alkyl group or a fluoroalkyl group, and z is an integer of 1 to 10,
• Y1 to Y3 are each independently, a divalent organic group represented by Chemical Formula 11,
• in the Chemical Formula 11,
• T is a tetravalent organic group represented by the Chemical Formula 10, and
• D1 and D2 are each independently, a C1-20 alkylene group, a C1-10 heteroalkylene group, a C3-20 cycloalkylene group, a C6-20 arylene group, or a C2-20 heteroarylene group,
• Y4 to Y6 are each independently, a divalent organic group represented by Chemical Formula 12,
• in the Chemical Formula 12,
• A is a Group 15 element selected from nitrogen (N), phosphorus (P), arsenic (As), antimony (Sb) or bismuth (Bi),
• R is hydrogen, or a C1-10 alkyl group,
• a is an integer of 1 to 3, and
• at least one of Z1 to Z4 is nitrogen, and the others are carbon,
• Y7 to Y9 are each independently, a divalent organic group represented by Chemical Formula 13,
• in the Chemical Formula 13,
• R15 and R16 are each independently, hydrogen, halogen, cyano, nitrile, C1-10 alkyl, C1-10 alkenyl, C1-10 alkoxy, C1-10 fluoroalkyl, or C1-10 fluoroalkoxy,
• p and q are each independently, an integer of 0 to 4,
• L2 is a single bond, —O—, —CO—, —S—, —SO2—, —C(CH3)2—, —C(CF3)2—, —COO—, —(CH2)y—, —O(CH2)yO—, —O(CH2)y—, —NH—, —NH(CH2)y—NH—, —NH(CH2)yO—, —OCH2—C(CH3)2—CH2O—, —COO—(CH2)y—OCO—, or —OCO—(CH2)y—COO—,
• y is an integer of 1 to 10,
• k and m are each independently, an integer of 0 to 1, and
• n is an integer of 0 to 3,
• in the Chemical Formula 16,
• A1 is at least one of mono- to tetravalent functional groups,
• j is an integer of 1 to 4,
• L4 and L5 are identical to or different from each other, and each independently, a C1-10 alkylene group or a C6-20 arylene group, and
• R19 and R20 are each independently, a silicon-containing monovalent functional group.