A method of preparing polyurea resin composition comprises forming a prepolymer by mixing about 50 parts by weight to about 80 parts by weight of a polyol, about 4 parts by weight to about 8 parts by weight of a dispersant, and about 20 parts by weight to about 30 parts by weight of a first monomer containing an isocyanate group; forming a first composition by mixing the prepolymer with about 2 parts by weight to about 4 parts by weight of a second monomer containing an amine group; stirring and emulsifying the first composition with about 100 parts by weight to about 200 parts by weight of a solvent; and forming a second composition by further adding about 0.2 part by weight to about 1.5 parts by weight of the second monomer to the emulsified first composition and stirring the resulting composition.