Package

Abstract

A package includes: a packaging container having a containing section open at the top and formed by a bottom and by a peripheral wall rising from the peripheral edge of the bottom, the packaging container further having a flange formed thereon, the flange being provided along the entire circumference of the peripheral wall and protruding outward relative to the containing section from the upper end of the peripheral wall; a contained object contained within the containing section and producing vapor when heated; and a top seal joined to the flange along the entire circumference thereof to seal the inside of the containing section. The packaging container has a curved section where a part of the peripheral wall is curved toward the containing section. A maximum deformation point is formed in the curved section, the maximum deformation point being the point where the deformation of the peripheral wall is maximum when pressure within the containing section increases to deform the top seal. The deformed top seal and the flange are pulled in the direction in which the deformed top seal and the flange are separated from each other, and when pressure within the containing section exceeds a set value, the top seal is separated from the flange at the maximum deformation point to release vapor within the containing section.

1 . A package to be heated in a microwave oven, comprising:
 a packaging container that includes a containing part composed of a bottom part and a peripheral wall part and opening upward and that is provided with a flange part, the peripheral wall part rising from a periphery of the bottom part, and the flange part extending along a whole circumference of the peripheral wall part and projecting from an upper edge of the peripheral wall part outward with respect to the containing part;   a contained object that is contained in the containing part and that generates steam when heated; and   a top seal a portion of which is joined to the flange part along a whole circumference of the flange part to thereby seal the containing part,   wherein the packaging container includes a curving part that is a portion of the peripheral wall part, the portion curving to protrude toward the containing part, and a maximum deformation amount point is formed within the curving part, a deformation amount being largest at the maximum deformation amount point in the peripheral wall part when an inner pressure of the containing part increases to deform the top seal, and   wherein, when the package is heated in the microwave oven, the inner pressure of the containing part increases due to steam generated from the contained object or gas expansion through heating so that the packaging container and the top seal deform, a bending angle formed between the top seal and the portion joined to the flange part of the packaging container becomes larger at the maximum deformation amount point than a bending angle at any other point along the peripheral wall part except the maximum deformation amount point, the top seal thus deformed and the flange part are pulled away from each other, and the top seal peels from the flange part at the maximum deformation amount point when the inner pressure of the containing part exceeds a set value, whereby steam in the containing part is discharged.   
     
     
         2 . The package according to  claim 1 ,
 wherein the upper edge of the peripheral wall part includes a pair of sides opposing each other, and   wherein the packaging container includes the curving part at each of the pair of sides.   
     
     
         3 . The package according to  claim 2 ,
 wherein the upper edge of the peripheral wall part forms a substantially rectangular shape, and   wherein the packaging container includes the curving part at each of a pair of long sides of the rectangular shape.   
     
     
         4 . The package according to  claim 1 , wherein the packaging container includes a handle part provided to the peripheral wall part except the curving part. 
     
     
         5 . The package according to  claim 1 ,
 wherein the flange part includes a joining projection part projecting in a direction opposite from the bottom part and extending along the whole circumference of the flange part, and   wherein the top seal is joined to the joining projection part.   
     
     
         6 . The package according to  claim 1 , wherein the top seal is joined to the flange part so as to have a joining width that is substantially same throughout the whole circumference of the flange part. 
     
     
         7 . The package according to  claim 1 , wherein the contained object is food. 
     
     
         8 . The package according to  claim 7 , wherein the food is frozen food. 
     
     
         9 . The package according to  claim 1 , wherein the packaging container is made of resin or paper. 
     
     
         10 . A packaging container used in the package according to  claim 1 .