| 摘要 |
<p>PURPOSE:To increase surface rigidity of a bottom and maintain stably an upright posture for a long time in a heated atmosphere, by providing at the bottom a plurality of side-sectionally U-shaped ribs extending from a recessed portion, through a surface contacting portion, to a side wall end radially and projecting inside. CONSTITUTION:There are formed an recessed portion 5 which arcuately protrudes toward the inside of a container body 1; surface contacting portion 6 which surrounds the recessed portion 5, extends to a side wall end 3a to project in an annular form, and contacts a horizontal surface; six ribs 7 extending radially from the recessed portion 5, through the surface contacting portion 6, to the side wall end 3a. Ribs 7 are side-sectionally U-shaped and project toward the inside of the container body 1, with their thickness about the same as that of the recessed portion 5 and some corners 7a inside the recessed portion 5. This can increase the bending stress and surface rigidity of the bottom 4. Therefore, the bottom 4 inverts and externally expands to ensure a standing stability, even when the container body 1 is heated to increase inside pressure during transportation or storage.</p> |
