To easily curl the mouth part of a container made of a styrenic resin foamed sheet by reducing the wall thickness of a bent part under compression to shorten the distance up to a rear surface to improve heat conductivity and collapsing cells to allow them to approach a non-foamed state to enhance heat conductivity and performing preforming so as to obtain a thickness ratio optimum to curl treatment.
A container has a container main body 11 and the opening flange 14 extending to the outer periphery of the opening part of the container main body and the opening flange is subjected to curl processing to obtain a container made of a styrenic resin foamed sheet having a mouth part formed thereto. In this container, the opening flange is formed so as to have the horizontal part 14A parallel to the bottom surface of the container main body and the leading end part 14B is downwardly bent from the horizontal part at an angle of 45° or more. The thickness ratio of a region subjected to curl processing is set so that (wall surface part 11A of container main body):(horizontal part 14A):(leading end part 14B)=1:0.9:0.7-1:0.5:0.25 to perform curl processing to mold the mouth part.
KONDO KENICHI
KOBAYASHI SHIGERU
