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

A liquid crystal alignment composition comprising:

• (i) a copolymer for liquid crystal alignment agent including a repeating unit represented by Chemical Formula 1 below, a repeating unit represented by Chemical Formula 2 below and a repeating unit represented by Chemical Formula 3 below, wherein the repeating unit represented by Chemical Formula 1 below is contained in an amount of 5 to 74 mol % relative to the total repeating units represented by Chemical Formulae 1 to 3 below, and the repeating unit represented by Chemical Formula 3 below is contained in an amount of 10 to 90 mol % relative to the total repeating units represented by Chemical Formulae 1 to 3 below, and
• (ii) a compound having two or more epoxy groups,
• wherein the molecular weight of the compound having two or more epoxy groups is not more than 10,000, and the compound is contained in an amount of 0.1 to 30% by weight based on the weight of the copolymer for liquid crystal alignment agent,
• wherein the repeating unit represented by the Chemical Formula 1 is formed from a diamine that is a reaction product of a compound comprising X1 represented by Chemical Formula 4 and a compound comprising Y1 represented by Chemical Formula 5,
• in the Chemical Formulae 1 to 3,
• R1 and R2 are each independently hydrogen, or C1-10 alkyl, with the proviso that both R1 and R2 are not hydrogen,
• X1 is a tetravalent organic group represented by the Chemical Formula 4 below,
• in the Chemical Formula 4,
• R3 to R6 are each independently hydrogen, or C1-6 alkyl,
• X2 and X3 are each independently a tetravalent organic group derived from a hydrocarbon having 4 to 20 carbon atoms, a tetravalent organic group in which at least one hydrogen in the tetravalent organic group is substituted with a halogen, or a tetravalent organic group in which at least one —CH2— is replaced by —O—, —CO—, —S—, —SO—, —SO2—, or —CONH— such that oxygen or sulfur atoms are not directly linked, and
• Y1, Y2 and Y3 are each independently a divalent organic group represented by the Chemical Formula 5 below,
• in the Chemical Formula 5,
• R7 and R8 are each independently halogen, cyano, C1-10 alkyl, C2-10 alkenyl, C1-10 alkoxy, C1-10 fluoroalkyl, or C1-10 fluoroalkoxy,
• p and q are each independently an integer of 0 to 4,
• L1 is a single bond, —O—, —CO—, —S—, —SO2—, —C(CH3)2—, —C(CF3)2—, —CONH—, —COO—, —(CH2)z—, —O(CH2)zO—, —O(CH2)z—, —NH—, —NH(CH2)z—NH—, —NH(CH2)zO—, —OCH2—C(CH3)2—CH2O—, —COO—(CH2)z—OCO—, or —OCO—(CH2)z—COO—,
• z is an integer of 1 to 10,
• k and m are each independently an integer of 1 to 3, and
• n is an integer of 0 to 3, and
• wherein the compound having two or more epoxy groups is any one or more of the compounds represented by Chemical Formulae 11, 12 and 14 below:
• in the Chemical Formulae 11 and 12,
• R20 and R21 are each independently hydrogen, or halogen,
• R22 and R23 are each independently hydrogen, or methyl,
• h and i are each independently an integer of 0 to 3, and
• j is an integer of 1 to 20,
• in the Chemical Formula 14,
• w is each independently an integer of 1 to 10.