Thermal retention container

A thermal retention container for edibles, especially pizza, that is durable enough for multiple use but inexpensive of construction so as to permit early disposal is disclosed. The container is characterized by a cardboard outer housing having a pair of flanged closing panels to which housing and panels are internally affixed insulating panels. The container contains a plurality of shelves such as to permit transport and/or storage of a plurality of pizzas or the like.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to a limited-life thermal retention container which 
is particularly useful for storing or transporting hot or cold food. In a 
preferred embodiment, the thermal retention container of this invention is 
adapted to store and/or transport a plurality of pizzas. 
2. Background 
There is an ever-growing consumption of prepared hot and frozen food 
products. In both cases it is desirable to insulate the food product 
during storage or transport to retain its thermal properties. Insulating 
carriers used heretofore have generally been of one of two possible 
types--expensive, multi-use containers having a metal double-wall 
construction filled with fiberglass or other known insulators, and 
inexpensive single-use disposable consumer containers ranging from simple 
single-wall pizza boxes to insulated icecream bags to paper-foil laminated 
bags. The more expensive variety of carriers provide higher thermal 
retention efficiencies as compared to the aforementioned bags and boxes, 
but obviously are not economically purchased by or distributed to 
limited-use consumers. What is needed is an intermediate product--one that 
approximates the low cost characteristics of the disposable consumer 
products, but offers a prolonged life and the higher thermal retention 
properties of the more expensive, multi-use containers. 
Accordingly, it is the primary object of my invention to provide a thermal 
retention container which will have insulating properties approximating 
those of multi-use permanent containers but having a low cost construction 
permitting its use as a disposable consumer product. 
Another object of my invention is to provide a low cost thermal retention 
container which is durable enough to permit repeated use. 
STATEMENT OF THE INVENTION 
In accordance with my invention, a thermal retention container is provided 
that has a front-opening exterior housing defined by a back wall, opposite 
top and bottom walls, two opposite side walls and a two-door closable 
front all fabricated of cardboard. 
The term "cardboard" as used herein is intended to encompass corrugated 
cardboard, paper board and like equivalent paper products. The two 
closable front doors are hinged to the front edges of two opposite walls 
and have folded flanges perpendicular to their surface on their remaining 
three sides. The remaining front edges of the walls of the exterior 
housing are notched to receive the flanges when the doors are closed. Flat 
plastic foam inner panels corresponding in size to the inner surfaces of 
the top, bottom and back walls are attached thereto. Similar panels are 
attached to the inner surface of the front doors. A plurality of removable 
cardboard shelves are positioned inside the container. They are held in 
spaced parallel arrangement by plastic foam spacers located on the inner 
surfaces of the opposite side walls. These spacers can be separate blocks 
or they can be integral with additional flat plastic foam panels that are 
placed on the inner surfaces of the opposite side walls. 
The invention and its advantages will be further understood from the 
description of the preferred embodiment and the accompanying drawing.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now in detail to the drawing, wherein like reference numerals 
denote like parts throughout the several Figures, there is shown in FIG. 1 
an isometric essentially front view of a thermal retention container of 
this invention, generally designated 10. Container 10 includes a 
rectangular open faced outer housing and defined by bottom wall 11, top 
wall 12, parallel and opposite side walls 14 and 15 and back wall 16. This 
housing is made of cardboard, preferably singlewall corrugated board 
having a bursting strength of from about 175 to 300 pounds per square 
inch. The front opening is covered by moveable front closing panels 17 and 
19. These are hinged to a pair of opposite walls, here shown as bottom and 
top walls 11 and 12. Very suitably, they are merely extensions of the 
walls with creases providing the desired hinges. Closing panels 17 and 19 
have flanges on their remaining edges. These flanges are depicted 20, 21 
and 22 on panel 17 and 24, 25 and 26 on panel 19. These flanges are 
perpendicular to their carrying panels and may be separate and attached or 
preferably are constructed by suitably folding the edges of panels 17 and 
19. These flanges are positioned so that when closing panels 17 and 19 are 
closed, the flanges butt together in the center and are on the outside of 
walls 11 and 12 thereby effecting a good seal with walls 11 and 12. Walls 
11 and 12 carry notches 27 and 29 respectively to permit closing panels 17 
and 19 close tightly. These notches may be cut so as to assist in locking 
panels 17 and 19 in their closed positions. An additional closure means 
(not shown) very suitably is provided to lock closing panels 17 and 19 in 
their closed positions. This can be a tab and slot arrangement, a Velcro 
joining strip, an adhesive strip or of like simple and inexpensive 
construction. The bottom of container 10 has a flat sheet of insulation 
30. This and the other insulation is plastic foam, preferably low density 
polyurethane or polystyrene foam such as of a density of from about 0.4 to 
2.0 lb/cubic foot. Sheet 30 is of an effective heat retaining 
thickness--generally from about 1/2 to 3 inches thick, preferably from 
about 1 to about 2 inches thick. Insulation sheet 30 is affixed to bottom 
wall 11 by adhesives. A similar insulation sheet 31 is attached to the 
inner surface of top wall 12 while a similar sheet 32 is attached to the 
inner surface of back wall 16. Closing panels 17 and 19 have insulating 
sheets 34 and 35 attached to their inner surfaces. The size of sheets 34 
and 35 is controlled so that there is no interference with walls 11 and 12 
or the insulation thereon when the closure panels are closed. A plurality 
(2-8, generally 3 to 5) of shelves 36 are provided within container 10. 
These are held in position by spacer blocks 37. Shelves 36 are fabricated 
out of cardboard with its corrugation wave running from front to back, 
rather than side to side. The space between shelves is generally at least 
about 2 inches. Spaces 37 may be affixed to side walls 14 and 15 or may be 
held in place by vertical compression resulting from oversizing their 
vertical dimension slightly beyond the exact clearance. If the spacers 37 
are affixed to walls 14 and 15 this enables shelves 36 to be removable. 
This is preferred. Shelves 36 can be sized so as to extend to insulating 
sheets 34 and 35 in this embodiment as the flanges on panels 17 and 19 do 
not cut across them. Depending upon the use to which container 10 is 
sought to be put, this can enable larger, higher edible materials to be 
stored or transported. In a preferred embodiment, the shelves 36 are left 
in place so that shelves 36 divide the interior of container 10 into a 
plurality of about 2 inch high subcompartments. This size is excellent for 
accommodating pizzas, hors d'oeuvre, and like prepared foods. The 
subcompartments increase the container's efficiency because cardboard is a 
good insulator and the subcompartments individually have a lower heat 
capacity and thus are less prone to bring about changes in the temperature 
of the contained foods. In the same sense, this embodiment, with its top 
and bottom hinged front covers offers the advantage that half of the 
subcompartments can be accessed without disturbing the remainder. This 
cuts down on heat changes as well. 
In FIG. 2, an alternative configuration of container (10A) is shown in 
which the closing panels open from side to side rather than up and down. 
This embodiment presents the same arrangement of walls 11, 12, 14, 15 and 
16. Closing panels 17 and 19 are hinged from opposite sides 14 and 15, 
respectively. Notches 27 and 29 are present on walls 11 and 12, 
respectively, to accommodate and engage flanges 21 and 25 on the two 
closing panels. This configuration offers the feature that flanges 21 and 
25 cut across the shelves. Accordingly, the shelves should be notched if 
it is intended that they be extended out to where they contact the 
insulation sheets on the closing panels. 
Turning now to FIG. 3, an expansion of FIG. 2 at the lower hinge joint 
between closing panel 17 and wall 14 is presented. In FIG. 3, bottom wall 
11, front closure 17 and flange 20 are shown as are insulating panels 30 
and 34. The relationship of spacer blocks 37 and shelves 36 is shown. As 
shown, shelves 36 are set back behind from the edge of bottom 11 and 
insulation sheet 30. This enables closing panels 17 and 19 to be closed 
without their flanges 21 and 25 interfering with these shelves. 
Alternatively, shelves 36 could be notched to accommodate flanges 21 and 
25. FIG. 4 shows an alternative construction wherein spacer blocks 37 are 
part of a side wall insulation construction. In this embodiment, blocks 37 
are part of a one-piece integral plastic foam casting that includes a side 
insulating sheet grooved to accept shelves 36. In this construction, like 
the embodiment wherein spacer blocks 37 are affixed to walls 14 and 15, 
shelves can be removed. 
In FIG. 5, a simple top view of container 10A of the invention is provided. 
Walls 14, 15 and 16, top 12, and closing panels 17 and 19 are shown as are 
insulating panels 32, 34 and 35 as spacer blocks 37. This Figure shows 
panels 17 and 19 closed and depicts the engagement of their flanges into 
the notches in top 12. Closing means 39 is shown on panels 17 and 19. 
The foregoing disclosure of specific embodiments is merely illustrative of 
the broad inventive concepts comprehended by my invention, which invention 
is as described by the following claims.