Abstract: A separation membrane has high strength and low leakage property while maintaining high gas permeability using poly(4-methyl-1-pentene) excellent in chemical resistance and gas permeability. The separation membrane contains poly(4-methyl-1-pentene) as a main component, in which a ratio RA of a rigid amorphous of poly(4-methyl-1-pentene) in the separation membrane is 43% or more and 60% or less, a porosity is 30% or more and 70% or less, and a dense layer is provided on at least one surface.

Abstract: A sheet folding machine used with a copying machine has a first conveying mechanism provided in succession with the sheet discharging path of the copying machine and functioning to widthwise displace a sheet discharged through the sheet discharging path. A second conveying mechanism is arranged below the first conveying mechanism and is adapted to convey the sheet selectively in one direction and in an opposite direction. A switch assembly is provided at the sheet loading ends of the first and second conveying mechanisms for switching the delivery of the sheet to the first and second mechanisms so that the sheet is delivered through the first conveying mechanism to said second conveying mechanism or alternatively directly to the second conveying mechanism. A sheet folding mechanism disposed below the second conveying mechanism folds the sheet in two in a first direction perpendicular to the sheet conveyance direction.