Package and method of forming same

Abstract

A package wherein a plastic dome cover is releasably secured to a container by distorting a depending skirt of the cover so that it curls around and interlocks with a flange on the container. The cover being a material with known shrink characteristics, distortion of the skirt is achieved by the application of heat thereto, and the skirt is segmented to provide selective distortion. The amount of distortion as well as the location of the distortion are factors which cooperate to produce a predetermined interlock between the cover skirt and the container flange.

Description

BACKGROUND OF THE INVENTION

This invention relates to packaging and more particularly to the securing of a plastic dome cover to a container or like receptacle, such as an aluminum foil pan, and the package formed thereby. The resulting package is particularly useful for holding pies and the like which are decorated or covered with fruit, whipped cream or other culinary items.

Heretofore the application and securing of plastic domes to pans of this type has been accomplished by various types of snap-on features, by applying a plastic shrink tape around the perimeter of the pan and dome, or by heat shrinking a plastic overwrap or bag around entire package to hold the dome securely to the pan. Each of these methods and its resulting package has one or more of several disadvantages. The closure may be ineffective; the package may be difficult to open and difficult or impossible to effectively be reclosed; or the additional materials and extra steps necessitated in the application of the domes may make the package more expensive to produce or difficult if not impossible to produce on high speed production lines.

SUMMARY OF THE INVENTION

The present invention overcomes the disadvantages of the prior art and obtains the desired characteristics of a package of this type by providing a method whereby a preformed domed cover of biaxially oriented thermoplastic material is placed on the pan filled with its intended contents and heat is selectively applied to the cover to shrink selective portions of the cover and thereby secure the cover to the pan. The cover has a peripheral skirt which depends downwardly beyond a corresponding outwardly extending flange on the pan. When heat is applied to the flange area, the skirt shrinks and is tucked beneath the flange of the pan to effect the closure. The skirt is preferable segmented to permit easy removal from the pan and easy reclosure of the cover on the pan after part of its contents is removed. More particularly, the skirt has short portions which, when heat is applied thereto, curl just slightly around the outermost edge of the flange, and long portions which curl beneath the flange of the pan for a substantial portion of the lateral dimension thereof.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a view in perspective from the underside of a plastic dome cover having a depending skirt portion.

FIG. 2 is a view in perspective from the topside of a pan having an outwardly extending flange.

FIG. 3 is an elevational view showing the plastic dome cover seated on the pan flange.

FIG. 4 is a fragmentary cross-sectional view taken along lines 4--4 of FIG. 3 showing the relation of the cover skirt and the pan flange.

FIG. 5 is a view similar to FIG. 4 but showing distortion of the cover skirt upon application of heat thereto.

FIG. 6 is a fragmentary cross-sectional view taken along lines 6--6 of FIG. 3.

FIG. 7 is a view similar to FIG. 6 but showing distortion of the cover skirt.

FIG. 8 is a bottom view of pan having a cover secured thereto in accordance with the teachings of the invention herein disclosed.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawing, a domed cover generally designated by the numeral 10 is provided, the cover having a top wall 12, a side wall 14 depending downwardly from the top, a peripheral shoulder 16 extending outwardly from the side wall 14, and a peripheral skirt 18 which initially depends downwardly from the shoulder 16. As noted above, the skirt 18 is preferable segmented to permit easy removal thereof from the pan 20 and easy reclosure of the cover 10 on the pan 20. The skirt 18 has short portions 18a which are dimensioned so that when heat is applied thereto, curl just slightly around the outermost edge of the flange 26 of the pan 20, and long portions 18b and 18c which curl beneath the flange 26 for a substantial portion of the lateral dimension thereof. The shape of the skirt 18 prior to shrinking is best shown in FIGS. 4 and 6, wherein there is illustrated the long and short portions, respectively. Preferably long portion 18b extends for a relatively short distance along the periphery of the cover 10 in an opening area 19, and for a greater distance therealong, as indicated by 18c, opposite the opening area 19. The short portions 18a extend between the long portions 18b and 18c. This particular configuration of the skirt 18 and the reason therefor will be discussed more fully hereinbelow.

While the top wall 12 is shown to be planar and the side wall 14 is shown to be fluted and to extend generally downwardly and outwardly in a straight line, obviously any suitable shape of side wall and top wall could be employed.

The cover is formed from sheet stock of biaxially oriented thermoplastic and is preferably clear to provide for visibility of the contents in the completed package. Many plastics of this character are available, it being sufficient for purposes of the subject invention that the selected plastic have suitable shrink characteristics.

The pan 20 is preferably formed from aluminum foil and has a bottom wall 22, a side wall 24 extending upwardly and outwardly from the bottom wall 22 and a peripheral flange 26 extending outwardly from the upper end of the side wall 24.

To secure the cover 10 to the pan 20, the cover 10 is placed on the pan 20 so that the shoulder 16 of the cover 10 rests on the flange 26 of the pan and the skirt 18 of the cover 10 depends downwardly over the outside of the flange 26 as shown in FIGS. 4 and 6. Hot air is then applied upwardly from the bottom of the pan and because the side wall 24 of the pan 20 slopes upwardly and outwardly, the only portion of the cover 10 that is exposed to the direct blast of hot air is the skirt 18. Thus, this area shrinks around the flange 26 of the pan 20, thereby securing the cover 10 to the pan as shown in FIGS. 5 and 7.

With the description of the cover 10 given above, in its secured position on the pan 20, the long skirt 18b in opening area 19 and skirt 18c opposite opening area 19 will curl under the flange 20 for a substantial portion of the width of the flange 20 as shown in FIG. 5. The short skirts 18a curl just slightly under the flange 20 as shown in FIG. 7. With this construction it is possible for the consumer to open the package by lifting the skirt 18b in the opening area 19 and lifting the cover 10 from the pan 20. It is also possible to replace the cover on the pan by reversing this procedure after part of the contents have been removed.

It should be noted that of the entire circumferential length of securement of the cover to the pan, approximately one-half of the securement is by the short skirts 18a, while approximately one-half of the securement is by the long skirts 18b and 18c. As shown by reference to FIG. 8, long skirt 18c secures considerably less than one-half the total circumferential length of securement, and is effective in conjunction with skirt 18b to provide positive and substantial interlocking of the cover skirt with the pan flange. Obviously, lifting or distorting skirt 18b away from securement to the pan flange 26 also moves skirt 18a out of securement with the pan flange and permits sliding disengagement of skirt 18c from the pan flange.

As shown, the opening area 19 is located centrally between the short skirts 18a and opposite long skirt 18c. It is clear that the integrity of the package is maintained until and unless skirt 18b is lifted or otherwise distorted so as to move from securement with the pan flange 26.

It is thought that the invention and many of its attendant advantages will be understood from the foregoing description and it will be apparent that various changes may be made in the form, construction and arrangement of parts without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the form hereinbefore described being merely a preferred embodiment thereof.

Claims

What is claimed is:

1. A reclosable package comprising a circular pan having a bottom wall, a side wall extending upwardly and outwardly from said bottom wall, and a peripheral flange extending outwardly from the upper end of said side wall; a product in said pan; and a preformed circular dome cover of biaxially oriented thermoplastic material, said cover comprising a top wall, a side wall depending downwardly from said top wall, a peripheral shoulder extending outwardly from said side wall and a peripheral skirt depending downwardly from said shoulder, said shoulder overlying said pan flange, said skirt extending below said pan flange and having the periphery thereof curled beneath said flange, said skirt comprising long portions and short portions whereby said long portions curl under said flange a substantial portion of the lateral dimension of the flange and said short portions curl just slightly under the flange, said short portions comprising less than one-half the total circumferential length of said skirt, and at least one long portion being liftable from securement with the pan flange.

2. The reclosable package of claim 1 wherein the skirt comprises two short portions which are disposed on either side of the liftable one long portion, and an other long portion disposed opposite said one long portion.

3. The reclosable package of claim 2 wherein the other long portion of the skirt comprises less than one-half the total circumferential length of said skirt.