Abstract: A process for longitudinally stretching a polymeric film having thickened longitudinal edges while the film is constrained in the lateral dimension by a plurality of successive pairs of grippers, the improvement comprising first guiding the film with a first group of gripper pairs having a predetermined clearance therebetween; and then gripping the film with a second group of gripper pairs with a predetermined amount of force. An apparatus for use in the process is also disclosed.

Abstract: A process for longitudinally stretching a polymeric film having thickened longitudinal edges while the film is constrained in the lateral dimension by a plurality of successive pairs of grippers, the improvement comprising first guiding the film with a first group of gripper pairs having a predetermined clearance therebetween; and then gripping the film with a second group of gripper pairs with a predetermined amount of force. An apparatus for use in the process is also disclosed.

Abstract: Photosensitive element comprisng a polyester, e.g., polyethylene terephthalate, at least 0.008 inch (0.20 mm) thick bearing on both sides a polymeric water-vapor barrier layer at least 0.00001 inch (0.00025 mm) thick of a copolymer of vinylidene chloride containing at least 80% by weight of vinylidene chloride and minor amounts of alkyl acrylate, and itaconic acid, and on at least one side of said barrier layer, a layer of a photosenstive material, e.g., silver halide emulsion, diazo or photopolymer. The element in the form of a phototool limits dimensional change within 6 hours after exposure to a 5% Relative Humidity change to no more than 0.001 inch (0.025 mm) per 24 inches (60.96 cm).

Abstract: Photosensitive element comprising a polyester, e.g., polyethylene terephthalate, at least 0.008 inch (0.20 mm) thick bearing on both sides a polymeric water-vapor barrier layer at least 0.00001 inch (0.00025 mm) thick of a copolymer of vinylidene chloride containing at least 80% by weight of vinylidene chloride and minor amounts of alkyl acrylate, and itaconic acid, and on at least one side of said barrier layer, a layer of a photosensitive material, e.g., silver halide emulsion, diazo or photopolymer. The element in the form of a phototool limits dimensional change within 6 hours after exposure to a 5% Relative Humidity change to no more than 0.001 inch (0.025 mm) per 24 inches (60.96 cm).

Abstract: To increase the rate of production of polyester film in cases where such film is produced by extruding a molten polymer onto the quenching surface of a rotating casting wheel, the shell thickness of the casting wheel is reduced.