Polyester laminated film
Provided is a polyester laminated film having a double-sided heterogeneous coating layer, and more particularly, a polyester laminated film having an excellent antistatic property and post-processability.
1. A polyester laminated film comprising:
a polyester base film;
an good-adhesive coating layer formed on one surface of the base film; and
an antistatic coating layer formed on the other surface of the base film,
wherein after back-side transfer is performed on the antistatic coating layer and the good-adhesive coating layer at 40° C. for 3 days under a load of 50 kgf/cm 2 , surface resistance A of the good-adhesive coating layer and surface resistance B of the antistatic coating layer satisfy the following Equation 1:
1×10 4 ≦A−B.
in which A indicates the surface resistance (Ω/□) of the good-adhesive coating layer after back-side transfer, and B indicates the surface resistance (Ω/□) of the antistatic coating layer after back-side transfer.
2. The polyester laminated film of claim 1 , wherein the surface resistance of the good-adhesive coating layer before back-side transfer is 1×10 13 to 1×10 16 Ω/□.
3. The polyester laminated film of claim 1 , wherein the surface resistance of the antistatic coating layer before back-side transfer is 1×10 9 to 1×10 10 Ω/□.
4. The polyester laminated film of claim 1 , wherein the base film has a thickness of 100 to 250 μm, the good-adhesive coating layer has a dried coating thickness of 50 to 100 nm, and the antistatic coating layer has a dried coating thickness of 0.03 to 0.1 μm.
5. The polyester laminated film of claim 1 , wherein the good-adhesive coating layer is formed by applying a polyurethane coating composition containing a water dispersion polyurethane resin containing isocyanate terminal groups partially or entirely blocked by an inorganic acid salt.
6. The polyester laminated film of claim 5 , wherein the polyurethane coating composition contains 5 to 10 weight % of a water dispersion polyurethane binder containing the water dispersion polyurethane resin and water and having a solid content of 10 to 30 weight %, 0.1 to 0.5 weight % of silicone-based wetting agent, 0.1 to 0.5 weight % of colloidal silica particle, and residual water.
7. The polyester laminated film of claim 5 , wherein the water dispersion polyurethane resin is composed of 10 to 75 weight % of a linear polymer and 25 to 90 weight % of a branched polymer.
8. The polyester laminated film of claim 5 , wherein the water dispersion polyurethane resin is prepared by reacting 39 to 45 weight % of polyol, 0.3 to 1.2 weight % trimethylol propane, and 50 to 57 weight % of an isocyanate compound to each other to prepare a pre-polymer having an isocyanate terminal group and again reacting the pre-polymer with 3 to 4 weight % of an inorganic acid salt to block the isocyanate terminal group with ionic groups.
9. The polyester laminated film of claim 8 , wherein the water dispersion polyurethane resin has a weight average molecular weight of 10,000 to 20,000.
10. The polyester laminated film of claim 1 , wherein the antistatic coating layer is formed by applying an antistatic coating composition containing a binder resin and a quaternary ammonium sulfonate-based compound.
11. The polyester laminated film of claim 10 , wherein the antistatic coating layer contains the quaternary ammonium sulfonate-based compound at a content of 30 to 300 parts by weight based on 100 parts by weight of the binder resin and has the entire solid content of 5 to 10 weight %.
12. The polyester laminated film of claim 10 , wherein the binder resin is an acrylic resin having a glass transition temperature of 50 to 80° C.