Easily-openable packaging container having notched inner surface layer

A multilayer container comprising a multilayered structure shaped to define a container portion having an opening and a flange portion surrounding the opening, and a lid member covering the opening in the container portion;

• said flange portion including a planar portion arranged adjacent to said opening;
• said multilayered structure including a layer forming an inner surface layer of the container portion and another layer contacting the inner surface layer and being laminated thereto;
• a notch extending into said inner surface layer and being located at an inner peripheral portion of said flange portion, said notch being positioned inwardly of at least a part of the planar portion so that upward peeling of the inner surface layer away from said another layer allows at least a part of the inner surface layer in the planar portion of the flange portion of said multilayered structure to be separated from the another layer;
• said lid member having a planar portion heat-sealed to at least a part of the planar portion of the inner surface layer at a peripheral portion of the flange portion of the multilayered structure to provide a heat seal portion between the lid member and the inner surface layer, said notch being spaced from and located inwardly of said heat seal portion;
• said multilayered structure possessing an interlaminar strength smaller than a peeling strength exhibited by the heat seal portion between the lid member and the inner surface layer so that during upward peeling of the lid member, a portion of the inner surface layer remains attached to said lid member and separates from said another layer.