STRUCTURE FOR OPENING/CLOSING INJECTION PORT OF FLEXIBLE CONTAINER BAG

PROBLEM TO BE SOLVED: To make a cylindrical injection port into a flat configuration, and also making an open configuration into a predetermined configuration positively by forming a plurality of folded parts to be a gusset configuration at the cylindrical injection port in the circumferential direction, and superimposing and securing a pair of raised chevron cross-sectional opposite strips to each other in each folded part. SOLUTION: A respective pair of trough-folded parts 15, 15 and angle-folded parts 16, 16 extending along an axis 6 are formed at the cylindrical injection port 3 in the circumferential direction, and the injection port 3 is made into a gusset configuration. Following this, a respective pair of opposite parts of dog-leg cross section opposite strips in each folded part 15, 16 are superimposed and secured by welding. By this construction, since the cylindrical injection port 3 is a gusset configuration, as the cylindrical injection port 3 is made into a flat configuration or an open state together with a flexible container bag 1, each folded parts are folded more positively, thereby a predetermined configuration in each configuration can be accomplished more securely.