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

1. A liquid crystal aligning agent composition comprising:

a co-polymer including a first repeating unit including a repeating unit represented by Chemical Formula 1 or a repeating unit represented by Chemical Formula 2; and

a second repeating unit including a repeating unit represented by Chemical Formula 3:

wherein, in Chemical Formulas 1 to 3,

at least one of R 1 and R 2 is an alkyl group having 1 to 10 carbon atoms and the other is hydrogen,

at least one of R 3 and R 4 is a substituted or unsubstituted silyl group including a trimethylsilyl group and the other is hydrogen,

X 1 to X 3 are each a tetravalent organic group represented by Chemical Formula 4,

[Chemical Formula 4]

wherein, in Chemical Formula 4,

R 5 to R 10 are each independently hydrogen or an alkyl group having 1 to 6 carbon atoms,

L 1 is any one selected from the group of a single bond, —O—, —CO—, —COO—, —S—, —SO—, —SO 2 —, —CR 11 R 12 —, —(CH 2 ) Z —, —O(CH 2 ) Z O—, —COO(CH 2 ) Z OCO—, —CONH—, phenylene, and a combination thereof,

where R 11 and R 12 are each independently hydrogen, an alkyl group having 1 to 10 carbon atoms, or a fluoroalkyl group,

Z is an integer of 1 to 10, and

Y 1 to Y 3 are each independently a divalent organic group represented by Chemical Formula 5,

wherein, in Chemical Formula 5,

at least one of Q 1 to Q 4 is nitrogen and the rest are carbon, and

R 13 is hydrogen or an alkyl group having 1 to 6 carbon atoms.

2. The liquid crystal aligning agent composition of claim 1 , wherein the second repeating unit is contained in an amount of 0.1 mol % to 50 mol % based on the mole number of the total repeating units.

3. The liquid crystal aligning agent composition of claim 1 , wherein in Q 1 to Q 4 of Chemical Formula 5, one of Q 2 and Q 4 is nitrogen and the other is carbon, and Q 1 and Q 3 are carbon.

4. The liquid crystal aligning agent composition of claim 1 , wherein in Q 1 to Q 4 of Chemical Formula 5, Q 2 is nitrogen and Q 1 , Q 3 , and Q 4 are carbon.

5. The liquid crystal aligning agent composition of claim 1 , wherein in Chemical Formula 5, R 13 is hydrogen.

6. The liquid crystal aligning agent composition of claim 1 , wherein Chemical Formula 5 includes functional groups represented by the following Chemical Formulae 5-1 to 5-3:

wherein, in Chemical Formulae 5-1 to 5-3, Q 1 to Q 4 and R 13 are as defined in claim 1 .

7. A method for preparing a liquid crystal alignment film comprising the steps of:

coating a solution of the liquid crystal aligning agent composition of claim 1 onto a substrate to form a coating film;

drying the coating film;

irradiating the coating film with light immediately after the drying step or rubbing the coating film to perform an alignment treatment; and

heat-treating and curing the alignment-treated coating film.

8. The method for preparing a liquid crystal alignment film of claim 7 , wherein the liquid crystal aligning agent composition is dissolved or dispersed in an organic solvent to form the solution.

9. The method for preparing a liquid crystal alignment film of claim 7 , wherein the step of drying the coating film is performed at a temperature of 50° C. to 150° C.

10. The method for preparing a liquid crystal alignment film of claim 7 , wherein the light in the alignment treatment step is polarized ultraviolet rays having a wavelength of 150 nm to 450 nm.

11. The method for preparing a liquid crystal alignment film of claim 7 , wherein in the step of curing the coating film, the heat-treating of the alignment-treated coating film is performed at a treatment of 150° C. to 300° C.

12. A liquid crystal alignment film comprising an aligned cured product of the liquid crystal aligning agent composition of claim 1 .

13. A liquid crystal display device comprising the liquid crystal alignment film of claim 12 .