Pressure relief covers for frozen food containers

Abstract

Undesired bulging of sealed food containers occurring during blast freezing is overcome by providing covers with pressure-relief passageways or vents in the form of a plurality of depressions in the region where the covers contact the upper edge of the containers to which they are applied. An alternative, but less preferable, embodiment is to form shallow slots in the upper edges of the containers.

1 . A container and lid combination for use in freezing and storing fruit or other food comprising: 
 a plastic container comprising a side wall and a bottom wall formed integral with said side wall, said side wall having a top edge and an outwardly protruding locking flange; and    a plastic cover comprising a body portion and a rim formed integral with and surrounding said body portion, said rim comprising an annular flange surrounding said body portion and an annular wall attached to and depending from said annular flange in spaced relation to said body portion, said annular wall having means for interconnecting with said locking flange so as to secure said cover to said container in covering relation to the interior space of said container with said annular flange overlying and engaged with said top edge of said container;    characterized by pressure-relief passageways between said cover and said container in the region where said annular flange of said cover is engaged with said top edge of said container.    
   
   
       2 . A container and lid combination according to  claim 1  wherein said passageways are formed by mutually spaced depressions in said annular flange.  
   
   
       3 . A container and lid combination according to  claim 2  wherein said annular flange has a bottom surface, and said depressions are formed in said bottom surface.  
   
   
       4 . A container and lid combination according to  claim 1  wherein said depressions have a depth in the range of about 0.015 inch to about 0.025 inch.  
   
   
       5 . A container and lid combination according to  claim 1  wherein said passageways are formed by mutually spaced slots in said top edge of said container.  
   
   
       6 . A container and lid combination according to  claim 4  wherein said slots have a depth of about 0.015 inch to about 0.025 inch.  
   
   
       7 . A container and lid combination for use in freezing and storing fruit or other food comprising: 
 a plastic container comprising a side wall and a bottom wall formed integral with said side wall, said side wall having a top edge with an outwardly protruding bead; and    a plastic lid comprising a body portion and a rim formed integral with and surrounding said body portion, said rim comprising an inner wall section extending at an angle to said body portion, an outer wall section concentric with said inner wall section and forming a skirt, and an intermediate wall section disposed between said inner and outer wall sections, with said body portion having a top surface and a bottom surface and said intermediate wall section projecting above said top surface and said outer wall section extending below said bottom surface, said outer wall section having means for interconnecting with said bead so as to secure said lid to said container in covering relation to the interior space of said container with said intermediate wall section overlying and engaged with said top edge of said container;    characterized by pressure-relief passageways between said lid and said container in the region where said lid is engaged with said top edge of said containers.    
   
   
       8 . A container and lid combination according to  claim 7  wherein said passageways are formed by mutually spaced depressions in said intermediate wall section of said rim.  
   
   
       9 . A container and lid combination according to  claim 8  wherein said intermediate wall section has an underside, and said depressions are formed in said underside.  
   
   
       10 . A container and lid combination according to  claim 8  wherein said depressions have a depth in the range of from about 0.015 inch to about 0.025 inch.  
   
   
       11 . A container and lid combination according to  claim 7  wherein said pressure-relief passageways are in the form of shallow slots in said top edge of said container.  
   
   
       12 . A container and lid combination according to  claim 11  wherein said slots have a depth in the range of from about 0.015 inch to about 0.025 inch.  
   
   
       13 . A container and lid combination according to  claim 7  wherein said bead has a top surface that is an extension of said top edge.  
   
   
       14 . A container and lid combination according to  claim 13  wherein said top surface is slanted downwardly and outwardly from said top edge.  
   
   
       15 . A plastic cover for making a snap fit with a container that has a top edge and a locking flange extending around its container's periphery at or adjacent to its top end edge for interlocking with said cover, 
 said plastic cover comprising a crown and a rim formed integral with and surrounding said crown, said rim comprising an inner wall section, an outer wall section concentric with said inner wall section and forming a skirt, and an intermediate wall section disposed between and connecting the upper ends of said inner and outer wall sections, with said crown being recessed below said intermediate wall section and said outer wall section extending below said crown, means on the inside of said outer wall section for interlocking with a locking flange on the periphery of a container so as to lock said cover to the container, and a plurality of depressions formed in said inner wall section for providing pressure-relief passageways between said cover and a container to which said cover is attached.    
   
   
       16 . A plastic cover according to  claim 15  wherein said cover has a plurality of internal locking projections for interlocking with a locking flange on a container, and further wherein said depressions are located between adjacent ones of said locking projection.