US 3226236 A
Description (OCR text may contain errors)
Dec. 28, 1 B. L. WELLER 3,226,236
METHOD OF FORMING A FOOD PACKAGE Filed March 12, 1964 2 Sheets-Sheet 1 INVENTOR. BERTHOI. DLWELL. ER
%w/%wm Dec. 28, 1965 B. L. WELLER 3,226,236
METHOD OF FORMING A FOOD PACKAGE Filed March 12, 1964 2 Sheets-Sheet 2 30 -H 30 74 lhlllll )7 "in n M 24 INVENTOR. BERTHQLDZWELLER 3,226,236 METHOD OF FORMING A F801) PACKAGE Berthold L. Weller, Deerfield, IlL, assiguor to Kitchens of Sara Lee, Inc., Chicago, lit, a corporation of Maryland Filed Mar. 12, 1964, Ser. No. 351,329 Claims. (Cl. 99--171) This invention relates to packages for soft perishable products, such as bakery goods, and to methods of forming such packages.
Prior bakery product packages have been deficient in several important respects. In order to permit stacking of the packages one on top of the other, the cover is frequently made relatively rigid to prevent the soft upper surface of the product from being crushed by the package stacked thereabove. However, the rigid cover frequently damages the product it is intended to protect when the package is inverted or jostled to cause the prod ucts upper surface to strike the cover.
In order to obviate this problem the present invention provides a package construction having a rigid cover to permit stacking but which prevents the product from striking the cover when the package is inverted or jostled. This is achieved in the disclosed embodiment by a flexible plastic sheet which engages the products upper surface and is under tension to urge the product downwardly against the bottom of the package. When the package is inverted or jostled, the flexible sheet maintains the products upper surface spaced from the rigid cover top wall so as to prevent the latter from marring the product.
Another deficiency of prior bakery product packages resided in the relatively large air space surrounding the product, particuarly when employing relatively rigid packages of cardboard or the like. The large amount of air in contact with the product caused the latter to lose its freshness and to spoil, become stale, or decompose, within a relatively short time.
This tendency is substantially reduced by the present invention wherein the air space in contact with the product is minimized by the flexible sheet which is under tension and conforms closely to the contour of the product over which it extends. Furthermore, the subject invention permits the relatively small unfilled residual volume of space between the sheet and the package bottom to be filled with an inert gas, it the nature of the product warrants this added protection.
Another important advantage of the present invention resides in the structure and method for hermetically sealing the product from the atmosphere in a manner which is inexpensive, leakproof, and reliable, and without sacrificing the other advantages enumerated herein. This is achieved in the disclosed embodiment by crimping together the peripheries of the plastic sheet and the package bottom half and then directing hot air against the crimp. The plastic sheet is of heat-shrinkable material and its crimped periphery shrinks in the radial contraction of the sheet periphery causes it to become thicker and thereby to engage hermetically the crimped periphery of the pan so as to form an effective seal.
In the preferred embodiment of the invention, bakery goods are initially baked in a container such as an aluminum foil pan and after baking the goods extend above the top level of the container. After the goods are baked, they are frozen. A sheet of shrinkable plastic material is then placed over the top of the bakery goods so as to extend outwardly of the edges of the pan. Then a rigid dome-shaped cover is positioned on top of the pan and over the sheet of plastic material. Then the pan and the cover are connected one to the other by crimping a flange of the pan over and on top of the flange of the cover, thus sandwiching the shrinkable plastic material between the Patented Dec. 28, 1965 folded sections of the pan and the cover. The cover is provided with a plurality of apertures and the assembled package is then delivered to a position where hot air is blown against the overlapping edges of the shrinkable plastic sheet, and also through the apertures in the cover onto the top surface of the sheet. The plastic sheet shrinks down to provide a tight and close fit over the bakery goods and the sheet periphery thickens to seal the space between the cover and the foil pan container. This provides an effective gas-tight seal for the bakery goods or other perishable product.
Other objects and advantages of the invention are inherent in the structure and steps disclosed or will be understood if the following description is viewed in the light of the accompanying drawings of which:
FIG. 1 is a perpsective view of a package illustrating a preferred embodiment of the invention;
FIG. 2 is a transverse sectional view taken on line 22 in FIG. 1;
FIG. 3 is a transverse sectional view of a foil pan container having bakery goods positioned therein and illustrates the first step in forming the package;
FIG. 4 is a transverse sectional view showing a shrinkable plastic sheet loosely positioned over the goods;
FIG. 5 is a transverse sectional view showing a domeshaped cover loosely positioned over the plastic sheet;
FIG. 6 is a transverse sectional view showing a portion of the flange of the foil pan wrapped around the cover flange to form a structural bond between the cover, the pan, and the plastic sheet;
FIG. 7 illustrates the last step of heat shrinking the plastic sheet to form a gas-tight seal and to shrink the sheet against the goods.
Referring now to the drawings in more detail, there is illustrated a pacakage 10 that is particularly adapted for the packaging of frozen bakery goods or other soft perishable products. The package 10 comprises a foil pan 12 which can be of any suitable configuration adapted to hold the goods. In the disclosed embodiment of the invention the pan 12 is generally rectangular in configuration having a flat bottom 11 and upwardly inclined side Walls 13. The pan 12 can be of any bendable or malleable material such as aluminum foil or any equivalent material such as, for example, paper or plastic where suitable. The pan 12 is provided with an L-shaped upper rim or flange 14 extending around its entire periphery.
FIG. 3 illustrates a foil pan 12 having positioned there in bakery goods shown for purposes of illustration in the form of baked rolls 28. The latter may be baked in the pan 12 and during baking, rise to a point above the top level of the pan 12. After baking, the rolls 28 may be frozen by any known process if so desired.
Next, a sheet of shrinkable plastic material 26 is positioned over the baked rolls 28 as illustrated in FIG 4, and the plastic sheet 26 is of suflicient area to extend completely over the baked rolls 28 and also extend past the ends of the L-shaped upper rim of the pan 12. The sheet 26 is of plastic material of the well-known type having two stable conditions. If the material is in its first stable condition, it can be heated and stretched to cover an area larger than its original area and when the heat is removed it will remain in a second stable streached condition. However, if heat is properly applied to the plastic sheet in its second stable condition, it will shrink to its first stable condition. Sheets of this character may be made from polyvinyl chloride, heat shrinkable polyethylene stabilized rubber hydrochloride, asymmetrical amorphous rubber chloride, plasticized polyvinyl chloride, vinylidene chloride, or a plasticized copolymer of vinyl acetate and formaldehyde, and are known by such trade names as Pliofilm, Formvar, Snug Pak, Cryovac,
3 and Saran. Such materials have been described in patents to Calvert, No. 1,989,632, issued January 29, 1935; McCoy, No. 2,168,651, issued August 8, 1939; and Goodman, No. 2,420,310, issued May 13, 1947.
The shrinkable plastic material 26 is positioned between the pan 12 and the cover 16 so as to prevent the surrounding atmosphere from affecting the packaged goods after the package is assembled when the plastic sheet 26 is shrunk to tightly adhere to the packaged goods and also to seal the space between the adjacent flanged edges of the pan 12 and the cover 16.
The package is also provided with a generally rectangular dome-shaped cover provided with a flat top 18, slanted walls 20, and a horizontal flange 22 extending around its entire bottom periphery. The horizontal flange 22 fits snugly in the L-shaped upper rim 14 of the pan 12. The cover 16 can be made of any relatively rigid material and is preferably made of paper, cardboard, or formed plastic. The cover 16 can be of any configuration suitable for the particular goods being packaged. The cover 16 is provided with a plurality of apertures 24 through which hot air may be directed as will be described below.
The dome cover 16 is positioned on the foil pan 12 and on the sheet of shrinkable plastic material 26 as is illustrated in FIG. 5. The horizontal flange 22 of the cover is positioned so as to snugly fit in the L-shaped upper rim 14 of the pan 12. The particular configuration of the cover 16 is not critical inasmuch as it can be designed to cover the goods which may have various configurations. If it is desired to stack the dilferent packages 10, the cover 16 can be formed with a flat top wall 18 as shown.
Next, as illustrated in FIG. 6, the L-shaped upper rim 14 of pan 12 is crimped or folded around and over the horizontal flange 22 of the cover 16 thereby sandwiching the peripheral area of the shrinkable plastic material 26 therebetween and forming a good mechanical connection between the foil pan 12 and the cover 16. This operation may be done by hand or with an appropriate machine.
Finally, as illustrated in FIG. 7, the package 10 is completed by positioning jets 30 to blow hot air on the sheet of shrinkable plastic material 26. Jets 30 blow hot air through the heat admitting apertures 24 of the cover 16 onto the main body of the plastic sheet 26 thereby shrinking the latter into a tight fitting relationship over the baked rolls 28. Those jets 30 positioned adjacent the flange 14 of pan 12 and the flange 22 of cover 16 shrink the peripheral area of the sheet 26 in the radial direction so that it thickens and forms a gas-tight gasket or seal 41 between the flange 14 and the fiange 22.
The intermediate area of the plastic sheet 26, as a result of the heat shrinking, is under tension and engages rolls 28 to prevent movement of the rolls 28 particularly if the package unit 10 is turned over.
If desired, a sauce or other material can be introduced into the space 17 through the apertures 24. After the package 10 has been formed as described, a label can be placed on the top 18 of the dome cover 16 to cover the apertures 24.
The small residual space between plastic sheet 26 and pan 12, which is not filled by the product 28, may be filled with an inert gas. This is made feasible by the fact that the seal formed by flanges 14, 22 and the peripheral area 4. of sheet 26 is hermetically tight. The inert gas further retards the tendency of the product to become stale and enables the package to be stored for a greater length of time without deleterious effect upon the contents I claim: 1. A method of packaging a food product comprising: the steps of placing the product within a pan; placing a heat shrinkable flexible sheet over the product so that the outer periphery of said sheet overhangs the outer periphery of said pan; placing a cover over the flexible sheet; connecting together the outer peripheries of said pan, sheet and cover; hermetically sealing the outer periphery of the sheet to the outer periphery of the pan; and heat shrinking the sheet so that it engages the upper surface of the product under tension to urge the product downwardly against the pan and to conform approximately to the contour of said product upper surface. 2. A method of packaging a food product comprising: the steps of placing the product within a pan having side walls terminating below the upper surface of the product; placing a flexible heat-shrinkable sheet over the product so that the outer periphery of said sheet overhangs the outer periphery of said pan; placing over the plastic sheet a cover having a top wall spaced vertically from said product upper surface; hermetically heat-sealing the outer periphery of the plastic sheet to the outer periphery of the pan; and heat shrinking the plastic sheet so that it engages said product upper surface under tension to maintain the product spaced from said cover top wall and to conform approximately to the contour of said product upper surface. 3. A method of packaging a product as recited in claim 2 wherein the top Wall of said cover is formed with an aperture therethrough and said seat shrinking step comprises directing hot air through said aperture into the space between the cover and the plastic sheet.
4. A method of packaging a product as recited in claim 2 wherein said heat sealing step comprises crimping together the outer peripheries of the pan and plastic sheet, and then directing hot air against the crimped peripheries whereby the plastic sheet periphery shrinks radially and becomes thicker to hermetically engage the pan periphery. 5. A method of packaging a product as recited in claim 2 and comprising the step of filling the residual space between the sheet and pan with an inert gas.
References Cited by the Examiner UNITED STATES PATENTS 1,446,782 2/ 1923 Broun et al 1,936,312 11/1933 Snyder. 2,284,604 5/ 1942 Brooks 53-27 2,542,206 2/ 1951 Nichols 99-189 3,017,729 1/1962 Cheeley 53-30 X A. LOUIS MONACELL, Primary Examiner.
RAYMOND N. JONES, Examiner.