Container and seal bar

1. A container comprising a container body holding contents therein and a lid member for closing an opening of the container body, the container body and the lid member being sealed with each other by an annular seal portion formed along a flanged face of the opening, at a specified portion of the annular seal portion, there being provided a detaching seal portion which is detached in response to increase of pressure inside the container body associated with deformation of the container body;

wherein the annular seal portion is formed by a pressing operation of pressing the lid member against the flanged face via a seal bar having at its leading end an annular projection having a shape corresponding to the annular seal portion, a groove-like sunk portion corresponding to the annular projection being formed in the flanged face by the pressing operation;

at least a portion of the sunk portion formed in the detaching seal portion comprises an uneven groove having a cross sectional shape with a smaller curvature radius on its radial inner side than its radial outer side; and

the annular seal portion being formed by the leading end of the seal bar on both the radially inner side and the radially outer side of the uneven groove, and the uneven groove of the seal having a radially inner side and a radially outer side extending from a sealed portion formed by the leading end of the seal bar.

2. The container according to claim 1 , wherein the annular seal portion of the detaching seal portion includes a reverse-oriented annular seal portion which projects toward a radial inner side of the opening.

3. The container according to claim 2 , wherein there is provided an auxiliary detaching seal portion which connects opposed ends on the radial outer side of the reverse-oriented annular seal portion.

4. The container according to claim 1 , wherein:

an outflow channel for discharging the contents extends radially outwards from the detaching seal portion; and

at positions facing the outflow channel from the left and right sides thereof, there are provided non-detaching seal portions comprised of a plurality of annular seal portions extending along a circumferential direction.

5. The container according to claim 4 , wherein the detaching seal portion and the non-detaching seal portion are connected to each other via a pair of left and right connecting annular seal portions; and between a portion of the pair of connecting annular seal portions and the outflow channel, there are provided a pair of auxiliary non-detaching seal portions facing each other across the outflow channel therebetween.

6. The container according to claim 4 , wherein at a position of the flanged face of the container body corresponding to the outflow channel, there is formed an outflow groove sunk toward the bottom of the container body.

7. A seal bar used for sealing a container body of a container holding contents therein by a fusing/bonding operation between a lid member and an opening of the container body;

the seal bar including, at its leading end, an annular projection for pressing the lid member against the opening;

the seal bar forming, at a predetermined position in an annular seal portion formed between the opening and the lid member by the fusing/bonding operation, a detaching seal portion to be detached by an inside pressure inside the container body associated with deformation of the container body based on an external force;

wherein at least a portion of the annular projection corresponding to the detaching seal portion comprises an uneven projection having a radially outer side portion that extends from the leading end of the seal bar, and a radially inner side portion that extends from the leading end of the seal bar, the uneven projection having a cross sectional shape with a smaller curvature radius on its radial inner side than its radial outer side.