US 2031254 A
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Feb. 18,1936. R. B. DERR HEAT INSULATED FOOD PACKAGE Filed July 18, 1931 2 Sheets-Sheet 1 I? v IN\?TOR dim Feb. 18, 19.36. R. B. DERR HEAT INSULATED FOOD PACKAGE Filed July 18, 1951 Z'Sheet's-Sheet 2 lllllllll q \fi u. u. in mug WITNESSES Patented Feb. 18,1936
UNITED" STATES PATENT OFFICE.
HEAT INSULATED FOOD PACKAGE Ralph B. Derr, Oakmont, Pa, assignor to Aluminum Company of America, Pittsburgh, Pa., a
corporation of Pennsylvania Application July 18, 1931, Serial No. 551,669
quence of these and other factors the trade has continued to use containers of the type referred to, because they afforded the best results consistent with the required cheapness of the container and shipping costs.
The invention is illustrated in the accompanying drawings, in which Fig. 1 is a perspective view of one embodiment, the container being broken away at one corner to show the inner liners; Fig. 2 a development view' of one of the liners shown in Fig. 1; Fig. 3 an end view of the liner shown in Fig. 2, the formed liner being indicated by broken lines; Fig. 4 a plan view of the liner formed from the blank shown in Figs. 2 and 3, ready for use; Fig. 5 a view similar to Fig. 2, showing the otherliner; Figs. 6 and 7 plan and end views, respectively, of the liner formed from the blank of Fig. 5; and Fig. 8 a fragmentary sectional view through a container forming a modified embodiment.
I have found, and it .is upon this that my invention is predicated, that particularly satisfacto i! containers for perishable foods are had by providing a shipping carton with a hollow liner whose air-space-surrounding walls are covered with bright metal foil. invention result from the provision of this coating of metal foil surrounding a substantial- 1y dead air space, which renders the liners more resistant to heat transfer than when they are not so provided with foil.
the containers provided by the invention have markedly better heat insulating properties, and their emciency is enhanced, as compared with the containers used heretofore.
Thecarton and liner are formed from a material adapted to resist heat transfer, such as paper board, preferably corrugated paper board in accordance with the usual practice. The construction of the cartons is standardized and well understood in the art.
Hollow liners suitable for use in the practice of the invention may be made in various ways, but most suitably they. are of the tubular form presently to be described. Preferably, they are made from corrugated paper board consisting of a flat backing sheet to one side of which a corrugated sheet is attached, the liner being formed with the corrugated surface arranged interiorly of the liner, 1. e. surrounding the inner air space.
In accordance with the invention the air space surrounding walls of this liner are covered with bright metal foil suitably attached to the walls, as by an'adhesive applied to the peaks of the corrugations. 0r, foil covered by adhesive may be This invention relates to perishable foodstuff containers of the heat insulated type adapted for the transportation of such foodstuffs at or near a predetermined temperature, and its objects are to provide a heat insulated shipping container which is of simple and inexpensive construction, light in weight, more eflicient than those used heretofore, and whose use does not increase ultimate shipping costs as compared with prior containers.
Perishable foodstuffs, such as sea food, ice cream, and the like, which are to be kept at or near a desired low temperature during and after transportation, in. surroundings where there is an appreciable differential between that temperature and the surrounding atmosphere are,commonly packed in containers formed from material adapted to resist transfer of heat. frigerant, such as solid carbon dioxide, may be placed in the container, or the material may be refrigerated preliminarily and shipped without refrigerant. In both cases the container is depended upon to maintain the material at a safe temperature-until it reaches its destination, or is used, as the case may be.
Such containers generally take the form of cartons made from paper board, and usually from corrugated paper board, these materals being cheap and reasonably resistant to heat transfer. In order further to increase the heat insulating properties, such cartons are generally provided with liners of corrugated paper board. In addition to being resistant to heat transfer,. these liners provide dead air spaces which further minimize therate of heat transfer between the atmosphere and the contents of the package. I Such containers are capable of'preserving their contents at or below a desired temperature for V relatively short periods of time, these being dependent chiefly upon the temperature differential between the contents and the atmosphere, and upon the degree of insulation afforded by the box and its liners. At best the time during which these containers safely preserve their contents has been quite short, and because an increase in this safe period of even a few' hours is highly desirable there'has-been a demand for containers of improved heat insulating character. There is a practical limit to the increase in insulating efficiency obtainable by such liners, largely because the increased thickness necessitates the use of larger containers, and increases the weight, both factors increasing costs. Also, .for economical reasons it has not been feasible to use other well known. insulators.
The benefits of the In consequence,
I r 2,031,254 f used, the foil being pressed against the peaks. Preferably the foil covers the inner walls of the liner, so that one side of it is in contact with the air space within the liner, and on the other side it forms with the valleys between the corrugations further dead air spaces.
One embodiment of the invention is shown in Figs. 1 to 7 of the accompanying drawings. A corrugated paper board carton I of conventional construction is provided with tubular liners 2 and 3 collectively conforming substantially to the inner dimensions of the carton, these liners being illustrative of the preferred embodiment of the invention.
As shown in Figs. 2 to 4, liner 2 is formed from a rectangular sheet 4 of corrugated paper board of the type consisting of a flat backing sheet 5 and a corrugated sheet 6 connected to one side thereof. A sheet of bright metal foil 1 is attached to the corrugated side of the board, preferably by adhesive, such as asphalt, applied to the peaks of the corrugations.
Either before or after assembling in the manner just described, sheets 4 and I are provided with notches 8, Fig. 2. The composite sheet is creased to form longitudinal fold lines 9 and transverse fold lines [0. The liner is then formed by folding the sheet along lines 9 to form an elongate tubular structure having the foil layer 1 covering its inner walls. An end elevation of the tube thus formed is shown in dotted lines in Fig. 3. The edges of the folded structure are then connected, as by a strip H of gummed tape. Upon folding the tube along lines Ill there is formed the completed liner shown in Figs. 1 and 4, adapted to extend aroundfour body sides of carton I. In thus folding, notches 8 act to provide a substantially closed tube, maintaining a practically dead air space within.
Liners 3 are disposed adjacent the remaining two sides of the container. these being the top and bottom -in the embodiment shown. Like liner 2, these are made from a corrugated sheet 4 having its corrugations covered by a sheet I of bright metal foil. The composite sheet is provided with fold lines 12 along which it is folded to produce the flat tubular liner shown in Figs. 6 and '7. The free edges are connected by a strip of tape H Actual tests have'shown the boxes constructed in accordance with this invention to be capable of maintaining their contents at a satisfactory safe temperature for a'substantially longer period of time than boxes not so constructed. In one set of tests a corrugated paper carton hav ing the standard liner consisting of four layers of corrugated paper not covered with foil, was compared with cartons of the same size provided with foil covered liners like those just described. In
each of these boxes there was placed 8.5 pounds of solid carbon dioxide, and the time of evaporation of the refrigerant was measured in a constant temperature room. The tests showed that the ordinary package having 4 layers of corrugated paper as a liner retained a portion of the refrigerant for about thirty-nine hours. Cartons pro vided with the improved hollow liner covered with foil retained refrigerant for fifty hours.
These tests show that the liners used in accordance with the invention render the containers much more resistant to heat transfer than those that have been commonly used. The liners do not occupy any greater volume of the carton capacity than the multi-layer liners now used, and are lighter than those liners. While various bright metal foils may be used for the purposes of the invention, aluminum foil is particularly desirable, and is preferred, because of its lightness and its availability in very light gauges. Also, aluminum foil does not readily lose its brightness.
The heat insulating ability of the containers just described may be increased further by a modification of the invention in which the exposed surfaces of the inside or outside of the carton are also covered with bright metal foil. My tests have shown that the greatest resistance to heat transfer is obtained by covering the outside of the carton with the foil, for which reason this embodiment is preferred.
This embodiment is shown in the fragmentary cross-sectional view of Fig. 8. A carton I provided with hollow foil-lined liners 2 and 3*, for instancewith those described hereinabove, is covered on the outside with bright metal foil l5 suitably attached to the cartonf as by an adhesive. Whether the carton be covered on the inside or on the outside, the resistance to heat transfer is increased. Thus, in the last mentioned tests which were conducted under conditions identical with those of the previously mentioned tests, the containers having the inner surfaces of the carton covered with aluminum foil retained refrigerant for fifty hours, while those covered with such foil on the outside still contained a portion of the solid carbon dioxide at fifty-three hours.
In either embodiment the foil covering does not add appreciably to the weight or ultimate cost. The containers provided by the invention make possible transportation for longer distances than with the cartons now used, or for equal distances better and safer refrigeration, less refrigerant being required. Because the weight is not increased, and is, in fact, usually decreased, or the capacity of a container of given weight is increased, the new containers increase the ratio of pay load to total weight. These factors afford substantial economies, and they offset the only added expense, that of the metal foil.
According to the provisions of the patent statutes, I have explained the principle and mode of operation of my invention and have illustrated and described what I now consider to represent its best embodiment. However, I desire to have it understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.
1. In a paper board carton for transportation of perishable foodstuffs, a heat-insulating liner formed of paper board corrugated on one side and having a sheet of bright pliable metal foil connected to the peaks of the corrugations, said liner shaped to provide a hollow tubular structure of substantially rectangular cross-section with said pliable metal foil forming inner walls surrounding an air space. 1
2. In a paper board carton for transportation of perishable foodstuffs, a heat-insulating liner formed of paper board one side of which is cor-' rugated to form peaks and intervening valleys and having its corrugated surface covered with a sheet of bright pliable metal foil connected to the peaks of said corrugations and forming dead air spaces with said valleys, said heat-insulating liner shaped to provide a hollow tubular structure of substantially rectangular cross-section with sa d pliable metal foil forming inner walls surrounding an air space.
paper having opposed notches formed in opposite sides thereof defining a plurality'of. connected sections, the material of each section being folded longitudinally upwardly from the opposite edges inwardly and downwardly to form a plurality of divide-d tubular air spaces, the, material of said strip being folded transverselyto bring the adjacent ends of the dividing tubular air spaces into registry to form a continuous closed polygonal structure having divided communicating hollow walls. I
1. A heat-insulating liner for packagesvcomprising an elongated unitary strip of corrugated paper having opposed notches formed in'opposite sides thereof defining a plurality of connected sections, said notches having parallel sides and V-shaped innergends', the material of each section being folded, "longitudinally upwardly from the opposite ed'ges inwardly and downwardly to form a plurality of divided tubular air spaces, the material of said strip being folded transversely to bring the adjacent ends of the'tubularair spaces into registry with the sides of the v-shaped portion of the notches meeting along said upwardly folded portion and with the parallel side portions of said notches meeting along the inwardly and downwardly folded portions to form RALPH B. DERR.