Abstract: Embodiments relate to a polyamide-imide film that secures excellent tensile toughness and elastic restoring force, and a process for preparing the same. The polyamide-imide film comprises a polyamide-imide polymer formed by polymerizing a diamine compound, a dianhydride compound, and a dicarbonyl compound, wherein the area value up to the yield point derived by the 0.2% off-set method on a stress-strain curve of the polyamide-imide film as measured using a universal testing machine (UTM) is 80 to 150 J/m2.

Abstract: Embodiments relate to a process for preparing a poly(amide-imide) film and a poly(amide-imide) film prepared thereby. The process is capable of preparing a poly(amide-imide) film that is excellent in optical properties and mechanical properties.

Abstract: Disclosed herein is a mandrel configured to be used in a winding process for manufacturing a jelly roll type electrode assembly using a long sheet type stack of a cathode/separator/anode structure, wherein the mandrel is oval in a section perpendicular to a rotational central axis of the mandrel and is divided into a first mandrel part located at one side of a central region of the mandrel, in which an end of the sheet type stack is fixedly fitted, and a second mandrel part located at the other side of the central region of the mandrel, and the first mandrel part and the second mandrel part each include a main body part having a region in which the sheet type stack is fitted in an engaged state and an exchange part, detachably mounted to the main body part, having an end of a major axis of the mandrel.

Abstract: Disclosed herein is a mandrel configured to be used in a winding process for manufacturing a jelly roll type electrode assembly using a long sheet type stack of a cathode/separator/anode structure, wherein the mandrel is oval in a section perpendicular to a rotational central axis of the mandrel, a length ratio of a major axis to a minor axis of the mandrel being 1.5 or more, and a tilt of an outer side of the mandrel is continuously changed from an end of the minor axis of the mandrel to an end of the major axis of the mandrel in the section perpendicular to the rotational central axis of the mandrel.

Abstract: Disclosed herein is a mandrel configured to be used in a winding process for manufacturing a jelly roll type electrode assembly using a long sheet type stack of a cathode/separator/anode structure, wherein the mandrel is oval in a section perpendicular to a rotational central axis of the mandrel and is divided into a first mandrel part located at one side of a central region of the mandrel, in which an end of the sheet type stack is fixedly fitted, and a second mandrel part located at the other side of the central region of the mandrel, and the first mandrel part and the second mandrel part each include a main body part having a region in which the sheet type stack is fitted in an engaged state and an exchange part, detachably mounted to the main body part, having an end of a major axis of the mandrel.

Abstract: Disclosed herein is a mandrel configured to be used in a winding process for manufacturing a jelly roll type electrode assembly using a long sheet type stack of a cathode/separator/anode structure, wherein the mandrel is oval in a section perpendicular to a rotational central axis of the mandrel, a length ratio of a major axis to a minor axis of the mandrel being 1.5 or more, and a tilt of an outer side of the mandrel is continuously changed from an end of the minor axis of the mandrel to an end of the major axis of the mandrel in the section perpendicular to the rotational central axis of the mandrel.