Coupling/uncoupling method, plastic coupler and envelop, bag and binder

摘要

A plastic fastener having a first segment 10 A with a protrusion 12 formed on a first base 11 , the protrusion 12 having a stopper hook on its end and having identical sections in a direction shown by arrow B, and a second segment 10 B with a groove 16 formed on a second base 15 , the groove being for nipping the hook of the protrusion 12 and having identical section in the direction shown by arrow B. The protrusion 12 and the groove 16 come into engagement with each other by pressures in directions shown by A and A' applied from respective back sides of the first base 11 and the second base 15 , and the engagement is not canceled by forces in directions opposite to the directions A and A'. The engagement can be canceled only by sliding the protrusion 12 together with the first base 11 and the groove 16 together with the second base 15 in directions shown by arrow B and B'.