Abstract: A multilayer sheet including a transparent film with a total light transmittance of 85% or more in accordance with ISO 13468, a coating layer disposed on a first surface of the transparent film, and an elastic film disposed below a second surface of the transparent film is disclosed. The Martens hardness HM measured on a surface of the coating layer is 180 N/mm2 or more.

Abstract: The embodiments relate to a polyamide-based film that is excellent in optical properties and mechanical properties, to a process for preparing the same, and to a cover window and a display device comprising the same. It comprises a polyamide-based polymer and a filler in an amount of 600 ppm or more relative to the weight of the polyamide-based polymer, wherein when the 3D surface roughness thereof is measured, the number of summits per unit area (Sds) is 4,400/mm2 or less.

Abstract: The embodiments provide a polyamide-imide-based film, which comprises a polyamide-imide-based polymer, wherein when the coefficients of thermal expansion in the MD direction and TD direction of the film are measured at an interval of 5° C. in a temperature range of 300° C. to 365° C., respectively, the temperature at which the coefficient of thermal expansion in the MD direction or the coefficient of thermal expansion in the TD direction changes from a positive value to a negative value is 330° C. to 345° C., a process for preparing the same, and a cover window and a display device comprising the same.

Abstract: The embodiments provide a polyamide-based film, which comprises a polyamide-based polymer and has an RSRA value of 3.4 m/N to 5.0 m/N as represented by the following Equation 1 based on the thickness of the film of 50 ?m, and which is excellent in loop stiffness, static flexural characteristics, and folding characteristics while securing mechanical and optical properties at least a certain level, a process for preparing the same, and a cover window and a display device comprising the same. <Equation 1> RSRA=(RSRMD+RSRTD)/2 In Equation 1, RSRMD is the loop stiffness value measured with the MD direction of the film as the longitudinal direction at room temperature, and RSRTD is the loop stiffness value measured with the TD direction of the film as the longitudinal direction at room temperature.

Abstract: The embodiments aim to provide a polyamide-imide-based film, which has a content of nitrogen (N) elements in the film of 6 to 7.5% by weight based on the sum of the weights of carbon (C), hydrogen (H), oxygen (O), and nitrogen (N) elements in the film, whereby it is uniform in quality and excellent in mechanical properties and optical properties, a process for preparing the same, and a cover window and a display device comprising the same.