Ink composition, and method of forming pattern, color filter and method of preparing color filter using the same

An ink composition comprising:

• a binder resin comprising a copolymer of monomers represented by the following Formula 2a, Formula 2b, Formula 2c, and Formula 2d:
• wherein R4 is hydrogen, an alkyl group having 1 to 6 substituted or unsubstituted carbon atoms, or an alkenyl group having 2 to 6 substituted or unsubstituted carbon atoms;
• R5 is an alkyl group having 1 to 6 substituted or unsubstituted carbon atoms, or an alkenyl group having 2 to 6 substituted or unsubstituted carbon atoms;
• and R6 and R7 are each independently hydrogen or an alkyl group having 1 to 6 carbon atoms;
• a multifunctional monomer having an ethylenic unsaturated double bond;
• a coloring agent;
• a solvent;
• and
• a polymerization initiator represented by the following Formula 1:
• wherein each of R1 , R2, and R3 is independently hydrogen, halogen, a linear, branched or cyclic alkyl group having 1 to 18 substituted or unsubstituted carbon atoms, a linear, branched or cyclic alkoxy group having 1 to 18 substituted or unsubstituted carbon atoms, an alkylcarbonyl group having 2 to 18 substituted or unsubstituted carbon atoms, an alkoxycarbonyl group having 2 to 18 substituted or unsubstituted carbon atoms, a carboxyl group, a mercapto group, a cyano group, a hydroxyl group, a nitro group, a substituted or unsubstituted phenyl group, a substituted or unsubstituted benzyl group, or a substituted or unsubstituted naphthyl group;
• and
• wherein X− is selected from the group consisting of a halogen ion, OH−, ClO2−, a sulfonate ion, a sulfate ion, a carbonate ion, a phosphate ion, a fluorophosphate ion, a borate ion, AlCl4−, BiF6−, a fluoroantimony ion, and a fluoroarsenic ion.