Abstract: A method of producing a polyimide film, including obtaining a polyamic acid including a repeating unit of Chemical Formula 1: wherein Ar1 and Ar2 are described in the specification; imidizing the polyamic acid to obtain a partially imidized polyimide; determining a sub-Tg temperature of the partially imidized polyimide; and heating the partially imidized polyimide in at least two steps to obtain a polyimide film, wherein a step transition temperature range is within the sub-Tg temperature ±30° C.

Abstract: A method of preparing an optical film, preparing a coating composition including an amic acid-containing polymer represented by Chemical Formula 1 and at least one polymerization aid selected from an alkyl phosphite, an aryl phosphite, an alkyl phosphate, and an aryl phosphate; providing the coating composition on a substrate to form a coating layer; and applying heat to the coating layer to prepare a cured film: wherein, in Chemical Formula 1, are the same or different in each repeating unit, and are each independently at least one selected from an aromatic organic group, an aliphatic organic group, and an alicyclic organic group, and 0?x?1.

Abstract: A method of preparing an optical film, preparing a coating composition including an amic acid-containing polymer represented by Chemical Formula 1 and at least one polymerization aid selected from an alkyl phosphite, an aryl phosphite, an alkyl phosphate, and an aryl phosphate; providing the coating composition on a substrate to form a coating layer; and applying heat to the coating layer to prepare a cured film: wherein, in Chemical Formula 1, are the same or different in each repeating unit, and are each independently at least one selected from an aromatic organic group, an aliphatic organic group, and an alicyclic organic group, and 0?x?1.

Abstract: A slot die includes a material distribution chamber configured to distribute a casting solution supplied to the material distribution chamber, and a lip in which a slot including an expansion portion is defined and through which the casting solution distributed in the material distribution chamber is discharged, where a width of the expansion portion taken in a first direction is expanded from one side of the expansion portion to a lip end facing the one side and the one side of the expansion portion is apart from the lip end by a predetermined length taken along a second direction which is perpendicular to the first direction and substantially parallel to a flow direction of the casting solution.

Abstract: A slot die includes a material distribution chamber configured to distribute a casting solution supplied to the material distribution chamber, and a lip in which a slot including an expansion portion is defined and through which the casting solution distributed in the material distribution chamber is discharged, where a width of the expansion portion taken in a first direction is expanded from one side of the expansion portion to a lip end facing the one side and the one side of the expansion portion is apart from the lip end by a predetermined length taken along a second direction which is perpendicular to the first direction and substantially parallel to a flow direction of the casting solution.

Abstract: A colorless transparent polyimide having a thickness of about 1 micrometer to about 250 micrometers, an average coefficient of thermal expansion measured in a machine direction and a transverse direction of less than or equal to about 80 parts per million/° C., an average in-plane retardation of less than or equal to about 20 nanometers, an average Yellowness Index of less than or equal to 6, and a transmittance for light at a wavelength of 370 nanometers to 740 nanometers of greater than or equal to about 80%.

Abstract: A film manufacturing apparatus includes: a material supply unit which supplies an intermediate film; a pre-heating unit which pre-heats the intermediate film supplied from the material supply unit; a stretching unit which stretches and performs a first heat-treatment to the intermediate film supplied through the pre-heating unit; a heating treatment unit which performs a second heat-treatment to the stretched intermediate film supplied from the stretching unit; a clipping device which clips lateral ends of the intermediate film to transfer the intermediate film and applies a transverse directional tension to the intermediate film; and a cutting device disposed in at least one of the stretching unit and the heat-treatment unit, wherein the cutting device separates the lateral ends from a center portion of the intermediate film by cutting the intermediate film.

Abstract: A method of producing a polyimide film, including obtaining a polyamic acid including a repeating unit of Chemical Formula 1: Chemical Formula 1 wherein Ar1 and Ar2 are described in the specification; imidizing the polyamic acid to obtain a partially imidized polyimide; determining a sub-Tg temperature of the partially imidized polyimide; and heating the partially imidized polyimide in at least two steps to obtain a polyimide film, wherein a step transition temperature range is within the sub-Tg temperature±30° C.

Abstract: A tenter apparatus for clipping a film includes a frame including a supporting surface supporting the film, and a clip arm which is installed to the frame and rotatable relative to the frame, clips the film along with the supporting surface of the frame and includes a plurality of first contact protrusions which is disposed at a bottom surface of the clip arm and contacts the film.

Abstract: A method of manufacturing a polyimide film includes: extruding a polyimide film including polyimide and a solvent; first drying the extruded polyimide film; stripping the first-dried polyimide film; second drying the stripped polyimide film to remove a residual solvent in the polyimide film; and stretching the second-dried polyimide film, wherein an amount of the residual solvent in the second-dried polyimide film is equal to or less than about 10 weight percent.

Abstract: A method of preparing an optical film, preparing a coating composition including an amic acid-containing polymer represented by Chemical Formula 1 and at least one polymerization aid selected from an alkyl phosphite, an aryl phosphite, an alkyl phosphate, and an aryl phosphate; providing the coating composition on a substrate to form a coating layer; and applying heat to the coating layer to prepare a cured film: wherein, in Chemical Formula 1, are the same or different in each repeating unit, and are each independently at least one selected from an aromatic organic group, an aliphatic organic group, and an alicyclic organic group, and 0?x?1.

Abstract: Disclosed herein is a polyimide film having an elongation from 50 to 150%, a tensile elastic modulus from 4 to 8 GPa, a tensile strength from 150 to 500 MPa, and a hygroscopicity of 5% or less. The polyimide film has high elastic modulus and tensile strength and an excellent elongation, and thus the polyimide film exhibits excellent material properties when it is used as a base film for TAB and COF, and its properties can be usefully modified using an additive to improve productivity and processibility thereof.