This invention relates to containers and is particularly concerned with improvements in product containers which are in the form of a tray and which may be fabricated from paperboard of a character which will enable the container to serve the dual purpose of packaging the product and permitting it to be processed in the same container. 
Tray containers have been developed heretofore which are particularly adapted for use in the marketing of a bakery product where the container may be of a character which will permit the product to be processed in the container in which it is packaged.  Products such as cakes, pastry, and the like which are generally in a flowable state initially, that is, in a liquid or semi-liquid condition, require that the container be leakproof when filled to a predetermined level with the product and capable of withstanding oven temperatures during the baking process without being destroyed by the heat in the oven.  For such products, the containers most commonly employed are formed from thin metal foil or relatively stiff metallic sheet material which can be pressed or shaped to the desired form and serve as part of the package in which the product is marketed.  Such containers are generally expensive and lacking in esthetic appeal since they do not readily accept the inks commonly employed in decorative printing.  Efforts have been made, with some degree of success, to provide non-metallic trays which are suitable for this purpose.  One such tray structure is disclosed in U.S. Pat.  No.  4,114,797 granted to Guelfo A. Manizza Sept. 19, 1978.  Another tray construction of this type, which is formed from paperboard having a filmlike heat resistant coating is disclosed in co-pending application Ser.  No.  148,908 filed May 12, 1980 by Guelfo A. Manizza and William M. Brown which has been developed for handling bakery products, such as bread, where a rectangular shape is desired so that the finished product will have the conventional rectangular shape of a loaf of bread.  In trays of this type having a coating in the form of a plastic film, the plastic film generally has shrink characteristics which differ from paperboard with the result that the side walls will buckle and have an unattractive appearance unless some provision is made to overcome the difference in shrinkage such as the scoring or cutting arrangement employed in Ser.  No.  148,908 at the fold line between the side wall panels and the flange which is most often desired so as to seat thereon the margins of a lid or for other reasons. 
Experience with tray structures of this type having a top flange on the side walls has shown that there is a need for a construction which will permit reinforcing the side walls against buckling or bulging and which will enable a satisfactory lid structure to be employed without detracting from the advantages obtained by the use of the flange and the film coated material. 
It is a general object, therefore of the present invention to provide an improved lid structure for open top trays of the type described which affords greater rigidity in the side walls, and provides the tray with greater capability in use, and which is economical to produce so as to compete with trays formed of metal foil, and the like. 
It is a more specific object of the invention to provide an improved lid structure and a method of securing the same on the top edge flange of a tray like container which is fabricated from a paperboard blank, preferably coated with a film forming heat resistant plastic material, which is cut and scored, so that it can be set-up with side wall panels upstanding from a rectangular bottom wall panel and connected at the corners by pairs of integral web members which are folded upon each other and secured against the faces of side walls, which have narrow top flanges for reinforcing the side walls and on which margins of the lid may be secured with the lid having provision for tearing out the major portion so as to expose the contents while leaving the marginal portions intact and secured in side wall reinforcing relation on the top edge flange. 
The herein disclosed and claimed invention comprises a lid or cover for a tray structure of the type having upstanding side walls with a relatively narrow top edge flange, which tray structure is fabricated from a cut and scored blank of paperboard material, with the top edge flange formation adapted to be adhesively adhered beneath the margins of the cover member and the cover member being cut scored on opposite faces adjacent its peripheral margins so that the major portion which the cut-scores surround may be torn out and a marginal strip will remain adhered to the top face of the tray flange so as to stiffen the flange and side wall.