WO1999032374A1

WO1999032374A1 - Insulated shipping container

Info

Publication number: WO1999032374A1
Application number: PCT/US1998/025897
Authority: WO
Inventors: David L. Nelson
Original assignee: Federal Express Corporation
Priority date: 1997-12-19
Filing date: 1998-12-07
Publication date: 1999-07-01
Also published as: AU1713399A; AR015203A1

Abstract

A thermally insulated container (20) ensures the preservation of temperature-sensitive goods during transportation. The walls of the container (20) comprise relatively thin, vacuum-sealed panels (10), which contain a rigid open-cell structure (14). The exterior of the panels (10) consists of a thin layer of plastic (12) having low gas and moisture permeability. The panels (10) can be made in six separate pieces, each representing a wall of a box, or formed together in a number of multi-panel combinations with a flexible hinge (15) separating each panel (10). Once arranged to accept temperature-sensitive goods in its cavity, the insulated container (20) can be placed in a protective enclosure (30).

Description

INSULATED SHIPPING CONTAINER

BACKGROUND OF THE INVENTION The present invention relates to containers for shipping temperature- sensitive goods, and more specifically to thermally insulated containers capable of maintaining sufficiently low temperatures during shipment to ensure preservation of the temperature-sensitive goods. The insulated shipping container of the present invention consists of vacuum sealed panels containing a rigid open cell structure for enhanced thermal insulation properties.

The shipment of temperature-sensitive goods requires containers that provide thermal insulation sufficient to maintain the goods at low temperatures. In many instances, the low temperature must be maintained for periods of 48 to 72 hours. Moreover, the containers often are subjected to high ambient temperatures, as would be the case, for example, during summer shipment. Conditions such as these demand enhanced thermal insulation.

In order to preserve temperature-sensitive goods during shipment, presently available insulated containers commonly use walls comprised of one-half to three inch thick polyurethane or expanded polystyrene foams for thermal barriers. The thermal resistance of such systems is typically in the range of 5 to 8 hr-ft -°F/Btu-in. When conditions impose more stringent cooling requirements, for example a three-day shipment of frozen goods exposed to high ambient temperatures, the goods are protected by packing excess dry ice inside the container. This approach results in obvious inefficiency and expense. For one, the excess dry ice increases the weight of the container. Also, the excess dry ice occupies space inside the container that otherwise could have been filled with more goods. Another problem arises when the shipment occurs by air since various transport aircraft limit the total dry ice allowed on board. The problems of this approach could be overcome by increasing the thickness of the thermal barrier walls. Yet while offering the benefit of higher thermal resistance, this solution would nonetheless produce unwanted results, namely, an overall increase in the size and weight of the container. Thermal insulating shipping containers also have been disclosed that use an evacuated region within a wall as a thermal barrier. For example, U.S. Patent No. 5,316,171 discloses a shipping container for transporting temperature- sensitive goods. The container is made from a plurality of multi-component panels that include at their center an evacuated region. The disclosed container is comprised of a complex arrangement of components.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an economical, insulated shipping container for the transportation of various temperature-sensitive goods, which container represents significant improvements over the prior art.

Another object is to provide an insulated shipping container with relatively thin walls having a high thermal resistance.

Additional objects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims.

To achieve the objects and in accordance with the purpose of the invention, as embodied and broadly described herein, the invention comprises a thermally insulated shipping container for holding and transporting temperature- sensitive products, the shipping container comprising a bottom panel, four side panels, and a top panel, wherein said panels comprise an evacuated thermal barrier material sealed within a plastic layer.

The thermal barrier material is comprised of a rigid open cell structure. This rigid open cell structure provides structural support to the evacuated region so to prevent the evacuated region from collapsing due to the pressure differential between the vacuum and the environment. In addition, the porous nature of the rigid open cell structure permits the removal of air and water (or other gases and liquids) during evacuation. Furthermore, the rigid open cell structure preferably consists of a nonmetallic material possessing a low thermal conductivity, which in combination with the vacuum delivers the intended result of a thermal layer with a high thermal resistance. Preferably, the rigid open cell structure is composed of a synthetic material such as rigid polyurethane or polystyrene foam or a paper- based material in a rigid structure, such as a hexaconical form.

The panels are placed within bags formed of impermeable material and are then subjected to a vacuum of approximately 0.5 to 0.01 torr, by conventional techniques. The bags are then sealed with the evacuated open cell structure inside, by presently available vacuum sealing techniques such as heat sealing, ultrasonic sealing, ultrasonic welding, and laser sealing. As a result, the evacuated material is encapsulated within the plastic outer layer. Two plastic layers having a combined thickness in the range of .002 to .010 inch have proven to perform well in this application, but other impermeable layers capable of encapsulating an evacuated open-celled structure in a sealed manner fall within the scope of the invention. The plastic layer preferably is covered by a low gas and moisture permeability film to prevent the seepage of gas or moisture into the vacuum. Preferably, the low permeability film consists of a layer of aluminum less than .001 inch thick. Again, other films that economically and efficiently prevent the seepage of gas or moisture through the plastic layer fall within the scope of the invention. To provide additional protection from damage (such as punctures), the panels can be enclosed in durable plastic film or sheet materials.

The insulated container of the present invention can be in the form of six vacuum sealed thermal barrier panels that are to be formed into the shape of a box that rests inside a protective enclosure. The protective enclosure may be of a type readily available and inexpensive, and constructed from such common materials as wood, plastic, or cardboard. The temperature-sensitive goods in turn rest inside the cavity formed by the thermal barrier panels.

The thermal barrier panels can be fabricated in a number of various patterns so that they can be formed into the shape of a box. In one embodiment, six separate and similarly sized rectangular panels are individually placed adjacent to the interior surfaces of the protective enclosure.

In another embodiment, four separate pieces form the insulated container. Two of the pieces are fabricated so each has two similarly sized, rectangular, vacuum-sealed panels separated by a thin, flexible plastic segment. The segment between the vacuum panels serves as a hinge that permits the piece to be bent in a right angle. With both pieces positioned with their respective panels perpendicular to each other, the four panels can be placed together to form the four side walls of a box. The two remaining panels are individual rectangular panels, as in the first embodiment, and form the bottom and top surfaces of the insulated container.

A third embodiment consists of two pieces. Each piece is comprised of three vacuum panels linearly arranged with a thin, flexible plastic segment between each vacuum panel. When the panels are bent at right angles at both flexible segments, the piece assumes a U-shaped form. Shaped this way, the two pieces can be combined to provide the insulated container that rests inside the protective enclosure.

A fourth embodiment is comprised of two separate rectangular vacuum panels and one piece containing four vacuum panels. The multi-panel piece, once bent in an orthogonal shape, forms the four sides of the insulated container while the two separate panels provide the bottom and top surfaces.

In a fifth embodiment, the insulated container is formed from one piece containing five vacuum panels and one separate vacuum panel. The multi-panel piece is fabricated in a pattern resembling a symmetrical cross. Four flexible plastic segments are located at the panel intersections. Five surfaces of an internal box are formed by bending the four outer panels at right angles to the center panel, with the outer panels comprising the side walls and the center panel comprising the bottom surface. The single rectangular panel completes the insulated container, providing the top surface.

In yet another embodiment, one piece is fabricated that contains six vacuum panels. The pattern of this embodiment can be clearly described by reference to the previous embodiment. In this embodiment the sixth panel is joined to an outer panel of the previous embodiment along the outermost edge, resulting in a pattern resembling an asymmetric cross. The insulated container is then formed by bending the panels at right angles along the flexible plastic segments in the same fashion as the previous embodiment. The outermost panel is likewise bent at a right angle, providing the top surface. The present invention provides improved thermal protection for the shipment of small bulk temperature-sensitive products. Whereas existing insulated containers designed for this purpose typically possess thermal resistances under 10 hr-ft²-°F/Btu-in., the presently disclosed container possesses a thermal resistance in the range of 15 to 30 hr-ft²-°F/Btu-in. Most preferably, the container has a thermal resistance within the range of 25 to 30 hr-ft -°F/Btu-in. This higher thermal resistance enables the temperature-sensitive products to survive longer periods of transportation while exposed to elevated temperatures.

In the case of frozen products that would be destroyed if they were to thaw, such as certain pharmaceutical products and biological products, the placement of dry ice in the container maintains product temperatures below freezing. An advantage of the present container is that, owing to its higher thermal resistance, it can keep the products frozen with less dry ice. By means of example, for containers of the present invention having a size of 12 inches by 12 inches by 12 inches and having evacuated foamed panels 1 inch thick, less than 30% dry ice was required than in other containers. In that example, as little as 10 pounds of dry ice maintained product temperatures below -5°C when exposed to external temperatures of 30°C for up to 72 hours, a period of time generally exceeding the time required for goods to be shipped to their destination. The reduced amount of dry ice results in the benefits of lower shipping weight, more available space to place goods, and easier compliance with aircraft restrictions on the maximum allowable volume of dry ice.

The present invention also effectively preserves unfrozen goods that nonetheless must remain in a cooled thermal environment below +5°C. Such a refrigerated environment is obtained by placing commercially available prefrozen gel packs in the container with the goods.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate several embodiments of the invention and together with the description, serve to explain the principles of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a partial section view of the panels of the insulated container of the present invention.

Fig. 2 is an exploded view of a six-piece embodiment of the insulated container of the present invention.

Fig. 3 is an exploded view of a four-piece embodiment of the insulated container of the present invention.

Fig. 4 is an exploded view of a two-piece embodiment of the insulated container of the present invention.

Fig. 5 is an exploded view of a three-piece embodiment of the insulated container of the present invention.

Fig. 6 is an exploded view of another two-piece embodiment of the insulated container of the present invention.

Fig. 6A is a plan view of the four-panel piece, prior to forming, of the embodiment shown in Fig. 6.

Fig. 7 is an exploded view of a one-piece embodiment of the insulated container of the present invention.

Fig. 7A is a plan view of the six-panel piece, prior to forming, of the embodiment shown in Fig. 7.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made in detail to the present preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.

As will be explained in more detail below, the thermal insulated container of the present invention represents a significant improvement over present insulated containers, where thermal barriers possess lower thermal resistances or contain metal layers. Those features result in shortcomings such as the need for an excessive amount of cold source material, additional weight, and increased manufacturing costs.

As shown in Fig. 1 , under the insulated container of the present invention, a high thermal resistance obtains from the design of the thermal barrier panels 10. The thermal barrier panels 10 are comprised of an evacuated region 18 where a rigid open cell structure 14 is enveloped within a plastic layer 12. The cellular nature of the material present in the evacuated region 18 offers important advantages, namely, structural integrity to the panel and a medium that allows for the evacuation of gases and liquids within the evacuated region, when a vacuum is applied to form the panels. Furthermore, the thermal conductivity of the preferred materials is low, which contributes to the high thermal resistance of the insulated container. Preferably, the rigid open cell structure 14 can be a rigid polyurethane or polystyrene foam or a rigid hexaconical paper-based material. One inch thick expanded polystyrene, open celled foam made by Dow Chemical Company has been successfully used in the application of the present invention. Other rigid open celled structures having similar strength and thermal characteristics also fall within the scope of the invention.

A panel 10 can be fabricated by placing a section of rigid open cell structure 14 in a relatively thin walled, flexible plastic bag. Preferably, the plastic bag possesses low gas and moisture permeability and has a wall thickness in the range of .002 to .010 inch. In one embodiment, a section of rigid open cell structure 14 smaller than 12 inches long by 12 inches wide by 1 inch thick is used. The plastic bag and rigid open cell structure 14 are then placed in a vacuum chamber, where a vacuum of approximately 0.5 to 0.001 torr extracts the water vapor and air (and any other liquids or gases) from the cells of the rigid open cell structure 14. The plastic container is then sealed, using conventional methods such as heat sealing, ultrasonic sealing, ultrasonic welding, or laser sealing, so the rigid open cell structure 14 now comprises an evacuated region 18 encapsulated by a plastic layer 12. Preferably, a completed panel 10 measures 12 inches long by 12 inches wide by 1 inch thick. Owing primarily to the absence of air and water vapor in this evacuated region 18, the high thermal resistance of the panel 10 is achieved.

In order for the panels 10 to maintain as high a thermal resistance as can be achieved, gas or moisture must not permeate into the evacuated region. The plastic layer 10 surrounding the evacuated region 18 impedes the passage of gas or moisture from the environment into the evacuated region 18. To further preserve the vacuum in the evacuated region 18, a low gas permeable film 16 can be formed on the outer surface of the plastic layer 10. Preferably, this film 16 is comprised of a deposited metallized layer, such as aluminum, less than .001 inch thick.

The panels 10 can be fabricated in individual pieces, as illustrated in Fig. 2, or in multi-panel pieces subsequently bent in right angles, as illustrated in Figs. 3 through 7A. Whichever embodiment is used, the panels 10 are arranged in a box-like manner within a protective enclosure 30. Thus arranged, the panels 10 combine to form the insulated container 20. Under the discrete panel embodiment shown in Fig. 2, the panels preferably are closely fitted to one another to minimize heat transfer through gaps. A space not exceeding .25 inch produces sufficient thermal insulation. Alternatively, the gaps can be sealed with tape to further reduce heat transfer through the container. Under the embodiments illustrated in Figs. 3 through 7A, no gaps exist between the multi-panel pieces by virtue of the integral seals 15, as shown in Fig. 1. The protective enclosure 30 is preferably a standard shipping container, constructed from wood, cardboard, plastic, or similar materials, and sized to accommodate the insulated container 20, while tightly holding the panels 10 in position to form a tight container. Further, the protective enclosure 30 includes surfaces for accepting standard labels, bar code identifications, address areas, and other information.

Once the insulated container 20 has been formed, temperature-sensitive products are placed inside it. For some temperature-sensitive products that are frozen, no additional cold source is needed. For shipment of temperature- sensitive products that require the maintenance of cool temperatures over longer periods, a cold source is also placed in the insulated container 20. In the case of frozen goods, such as pharmaceutical or biological goods, the addition of 10 pounds of dry ice maintains product temperatures below -5°C for a period of up to 72 hours. In the case of refrigerated goods, the addition of prefrozen gel packs can be used to maintain product temperatures at acceptable levels.

Fig. 2 shows six separate panels 10. As can be seen, the insulated container 20 is formed by having each panel 10 form one of the six surfaces of a box. Fig. 3, alternatively, shows the insulated container 20 constructed from four pieces. A pair of double-panel pieces, each bent in a right angle at the midline, form the four sides of the insulated container 20. Referring again to Fig. 1 , the multi-panel pieces are bent where the seal 15 separates discrete panels 10. Along the seal 15, the piece is easily bent because the thin, flexible plastic layer 12 alone occupies this area. In addition, the seal 15 preferably has a width in the range of .06 to .50 inch to provide a sufficient bend radius. The bottom and top surfaces of the insulated container 20 are formed by single panels 10.

The embodiment depicted in Fig. 4 utilizes two three-panel pieces to form the insulated container 20. Again, the pieces are bent at right angles along the seals 15 between the adjoining panels 10, resulting in two U-shaped pieces. In Fig. 5, an embodiment is shown where the insulated container 20 is constructed from three pieces. One piece is comprised of four panels 10 linearly joined, together forming the four sides of the insulated container 20 once bent in right angles along the seals 15. In this embodiment, as in Figs. 1 and 3, the bottom and top surfaces are formed by single panels 10.

Fig. 6 shows an insulated container 20 built from two pieces, a single panel and a five-panel piece. As illustrated in Fig. 6A, the five-panel piece is fabricated with one panel 10a in the center and four panels 10b, 10c, 10d, 10e joined and sealed along each edge of the center panel 10a. Referring back to Fig. 6, when the right angle bends are made, the center panel 10a becomes the bottom surface of the insulated container 20 and the four adjoining panels become the side surfaces 10b, 10c, 10d, 10e.

Fig. 7 shows an embodiment where but a single piece forms the insulated container 20. Here, as more clearly depicted in Fig. 7A, all six panels 10f, 10g, 10h, 10i, 10j, 10k are fabricated together, with four panels 10f, 10g, 10j, 10k linearly arranged and two panels 10h, 10i adjoining the remaining edges of an inner panel 10f. Referring back to Fig. 7, the piece is formed so the inner panel 10f sharing edges with the four panels 10g, 10h, 10i, 10j becomes the bottom surface of the insulated container 20. The four panels 10g, 10h, 10i, 10j immediately attached to the bottom surface panel 10f comprise the side surfaces, and the remaining, outermost panel 10k becomes the top surface. It will be apparent to those skilled in the art that various modifications and variations can be made in the insulated container of the present invention and in construction of this invention without departing from the scope or spirit of the invention. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.

Claims

What is claimed is:

1. A thermally insulated shipping container for holding and transporting temperature-sensitive products, the shipping container comprising a plurality of panels forming a housing with a lid, each of said panels comprising an evacuated thermal barrier material sealed within an impermeable layer.

2. The container of claim 1 wherein the thermal barrier consists of a rigid open cell structure.

3. The container of claim 2 wherein the rigid open cell structure is comprised of a polyurethane foam.

4. The container of claim 2 wherein the rigid open cell structure is comprised of a polystyrene foam.

5. The container of claim 2 wherein the rigid open cell structure is comprised of paper-based materials.

6. The container of claim 1 wherein said impermeable layer is a relatively thin layer of synthetic material.

7. The container of claim 6 wherein said synthetic material is plastic.

8. The container of claim 7 wherein the plastic layer is lined with a low gas permeable film.

9. The container of claim 8 wherein the low gas permeable film is a metallized film.

10. The container of claim 9 wherein the metallized film is comprised of a layer of aluminum .0005 to .0020 inches thick.

11. The container of claim 1 wherein the panels are one-quarter to three inches thick.

12. The container of claim 11 wherein the thermal resistance of the panels is within the range of 15 to 30 hr-ft²-┬░F/Btu-in.

13. The container of claim 1 wherein the container is box-shaped and the interior dimensions of the container are at least 12 inches wide by 12 inches long.

14. The container of claim 13 wherein the interior dimensions are no greater than two feet wide by two feet long.

15. The container of claim 13 wherein said container has an interior height of at least 12 inches.

16. The container of claim 13 wherein said container is placed inside a protective enclosure.

17. A thermally insulated shipping container for holding and transporting temperature-sensitive products, the shipping container comprising a plurality of panels forming a housing with a lid, each of said panels consisting essentially of an evacuated thermal barrier material sealed within an impermeable layer.

18. The container of claim 17 wherein the thermal barrier consists of a rigid open cell structure.

19. The container of claim 18 wherein the rigid open cell structure is comprised of a polyurethane foam.

20. The container of claim 18 wherein the rigid open cell structure is comprised of a polystyrene foam.

21. The container of claim 18 wherein the rigid open cell structure is comprised of paper-based materials.

22. The container of claim 17 wherein the impermeable layer is a plastic layer lined with a low gas permeable film.

23. The container of claim 22 wherein the low gas permeable film is a metallized film.

24. The container of claim 23 wherein the metallized film is comprised of a layer of aluminum .0005 to .0020 inches thick.

25. The container of claim 17 wherein the panels are one-quarter to three inches thick.

26. The container of claim 25 wherein the thermal resistance of the panels is within the range of 15 to 30 hr-ft²-┬░F/Btu-in.

27. The container of claim 17 wherein the container has a bottom panel, four side panels, and a top panel, and wherein the interior dimensions of the container are at least 12 inches wide by 12 inches long.

28. The container of claim 27 wherein said container has an interior height of at least 12 inches.

29. The container of claim 17 wherein said container is placed inside a protective enclosure.

30. The container of claim 17 wherein the container has insulation properties sufficient to maintain frozen products below -5┬░C for a period of up to 72 hours, when a frozen product and dry ice are held and transported within the container.

31. A thermally insulated shipping container for holding and transporting temperature-sensitive products, the container comprising a plurality of panels forming a housing with a lid, each of said panels comprising an evacuated thermal barrier material sealed within an impermeable layer, wherein at least two of said panels are connected by a hinging membrane formed from said impermeable layer.

32. The container of claim 31 wherein the hinging membrane is at least .06 inch wide by 12 inches long.

33. The container of claim 32 wherein the hinging membrane is within the range of .002 to .010 inch thick.

34. The container of claim 31 wherein the housing is comprised of:

(a) a first pair of side walls consisting of two panels orthogonally formed along one hinging membrane;

(b) a second pair of side walls consisting of two panels orthogonally formed along another hinging membrane;

(c) a floor consisting of a single panel; and

(d) the lid consisting of a single panel.

35. The container of claim 31 wherein the housing is comprised of:

(a) a first group of three surfaces consisting of three panels orthogonally formed along two hinging membranes; and

(b) a second group of three surfaces consisting of three panels orthogonally formed along two hinging membranes.

36. The container of claim 31 wherein the housing is comprised of:

(a) four side walls consisting of four panels orthogonally formed along three hinging membranes;

(b) a floor consisting of a single panel; and

(c) the lid consisting of a single panel.

37. The container of claim 31 wherein the housing is comprised of:

(a) four side walls and a floor consisting of five panels orthogonally formed along four hinging membranes; and

(b) the lid consisting of a single panel.

38. The container of claim 31 wherein the housing is comprised of six surfaces consisting of six panels orthogonally formed along five hinging membranes.