Polyamide-based film, and cover window and display device comprising same
The embodiments relate to a polyamide-based film excellent in optical properties, mechanical properties, and processing suitability and to a cover window and a display device comprising the same. The polyamide-based film comprises a polyamide-base polymer, wherein a dipolar solvent compatibility represented by the following equation is 18.5 to 24: Dipolar solvent compatibility=√{square root over ((σ d −δ1 d ) 2 +(σ p −δ1 p ) 2 )}. In the equation, σ d is a value of a dispersible component in surface energy of the polyamide-based film, σ p is a value of a polar component in surface energy of the polyamide-based film, δ1 d is a value of a dispersible component in Hansen solubility parameter of the dipolar solvent, and δ1 p a value of a dipolar component in Hansen solubility parameter of the dipolar solvent.
1. A polyamide-based film, which comprises a polyamide-based polymer, wherein a dipolar solvent compatibility represented by the following Equation 1 is 19.5 to 23.5:
Dipolar solvent compatibility=√{square root over ((σ d −δ1 d ) 2 +(σ p −δ1 p ) 2 )} [Equation 1]
in Equation 1,
σ d is a value of a dispersible component in surface energy of the polyamide-based film,
σ p is a value of a polar component in surface energy of the polyamide-based film,
δ1 d is a value of a dispersible component in Hansen solubility parameter of the dipolar solvent, which ranges from 13 to 17, and
δ1 p is a value of a dipolar component in Hansen solubility parameter of the dipolar solvent, which ranges from 5 to 13.
2. The polyamide-based film of claim 1 , wherein δ1 d in Equation 1 is 14 to 15.8.
3. The polyamide-based film of claim 1 , wherein δ1 p in Equation 1 is 6 to 10.
4. A polyamide-based film, which comprises a polyamide-based polymer, wherein a dispersible solvent compatibility represented by the following Equation 2 is 25.5 to 30:
Dispersible solvent compatibility=√{square root over ((σ d −δ2 d ) 2 +(σ p −δ2 p ) 2 )} [Equation 2]
in Equation 2,
σ d is a value of a dispersible component in surface energy of the polyamide-based film,
σ p is a value of a polar component in surface energy of the polyamide-based film,
δ2 d is a value of a dispersible component in Hansen solubility parameter of the dispersible solvent, which ranges from 7 to 10, and
δ2 p is a value of a dipolar component in Hansen solubility parameter of the dispersible solvent, which ranges from 0.1 to 15.2.
5. The polyamide-based film of claim 4 , wherein δ2 p in Equation 2 is 0.1 to 4.
6. The polyamide-based film of claim 4 , wherein δ2 d in Equation 2 is 7.5 to 9.6.
7. The polyamide-based film of claim 1 , wherein the polyamide-based polymer comprises two or more types of an amide-based repeat unit.
8. The polyamide-based film of claim 7 , wherein the two or more types of an amide-based repeat unit comprise a first amide-based repeat unit derived from a first dicarbonyl compound and a second amide-based repeat unit derived from a second dicarbonyl compound, and
an angle between two carbonyl groups contained in the first dicarbonyl compound is greater than an angle between two carbonyl groups contained in the second dicarbonyl compound.
9. The polyamide-based film of claim 1 , wherein the polyamide-based polymer comprises an amide-based repeat unit and an imide-based repeat unit at a molar ratio of 51:49 to 100:0.
10. The polyamide-based film of claim 1 , which, based on a thickness of the film of 50 μm, has a modulus of 4.5 GPa or more, a transmittance of 80% or more, a haze of 1% or less, and a yellow index of 3.5 or less.
11. A cover window for a display device, which comprises a polyamide-based film and a functional layer, wherein a dipolar solvent compatibility of the polyamide-based film represented by the following Equation 1 is 19.5 to 23.5:
Dipolar solvent compatibility=√{square root over ((σ d −δ1 d ) 2 +(σ p −δ1 p ) 2 )} [Equation 1]
in Equation 1,
σ d is a value of a dispersible component in surface energy of the polyamide-based film,
σ p is a value of a polar component in surface energy of the polyamide-based film,
δ1 d is a value of a dispersible component in Hansen solubility parameter of the dipolar solvent, which ranges from 13 to 17, and
δ1 p is a value of a dipolar component in Hansen solubility parameter of the dipolar solvent, which ranges from 5 to 13.
12. A display device, which comprises a display unit; and the cover window according to claim 11 disposed on the display unit.
13. The polyamide-based film of claim 4 , wherein the polyamide-based polymer comprises two or more types of an amide-based repeat unit.
14. The polyamide-based film of claim 13 , wherein the two or more types of an amide-based repeat unit comprise a first amide-based repeat unit derived from a first dicarbonyl compound and a second amide-based repeat unit derived from a second dicarbonyl compound, and
an angle between two carbonyl groups contained in the first dicarbonyl compound is greater than an angle between two carbonyl groups contained in the second dicarbonyl compound.
15. The polyamide-based film of claim 4 , wherein the polyamide-based polymer comprises an amide-based repeat unit and an imide-based repeat unit at a molar ratio of 51:49 to 100:0.
16. The polyamide-based film of claim 4 , which, based on a thickness of the film of 50 μm, has a modulus of 4.5 GPa or more, a transmittance of 80% or more, a haze of 1% or less, and a yellow index of 3.5 or less.