Thermally insulated container

Information

  • Patent Grant
  • 6234341
  • Patent Number
    6,234,341
  • Date Filed
    Thursday, March 16, 2000
    25 years ago
  • Date Issued
    Tuesday, May 22, 2001
    24 years ago
Abstract
A transport container comprises an insulating block. A plurality of layers of flexible insulating foam material form sides of the container and are mounted on the block which closes one end of the container. A pressure envelope applies pressure around the exterior of the sides and the block.
Description




TECHNICAL FIELD




This invention relates to a transport container for use in transporting temperature sensitive products and keeping them either cool or protecting them from chilling in transit, as required.




BACKGROUND ART




Certain products need to be kept cool whilst being transported from place to place by postal or courier services, particularly from a manufacturer or distributor to a consumer for the product concerned. Examples of such products are food products, pharmaceuticals and bio-chemicals including diagnostics, and they are generally known as “cold chain” products. Other products need to be protected from chilling during transport, particularly from freezing in air cargo, and in this specification these products are referred to as “warm” products. Examples of “warm” products include certain other foodstuffs and pharmaceuticals, and blood products.




“Cold chain” and “warm” products have until now generally been transported in thermally insulated rigid containers such as fabricated polystyrene foam boxes as an example, but such containers can be fragile, expensive and inefficient.




It is an object of the present invention to provide an improved transport container.




DISCLOSURE OF INVENTION




In accordance with the present invention, a transport container comprises an insulating block, a plurality of layers of flexible insulating foam material forming sides of the container and mounted on the block which closes one end of the container, and a pressure envelope for applying pressure around the exterior of the sides and the block.




Preferably the pressure envelope is a heat shrunk polyethylene envelope.




Preferred also the insulating block is formed from stiff polyethylene foam.




Preferred also the sides of a plurality of layers of said flexible insulating material at least one sheet of said flexible insulating material wound a plurality of times around itself to form said plurality of layers.




Preferred further said at least one sheet of said flexible insulating material is wound a plurality of times around itself and around at least a portion of the insulating block.




Preferred further at least a portion of the insulating block is attached to at least the outer edge of the outer layer of the plurality of layers of said flexible insulating material at said one end of the container.




Preferred further said at least one sheet of said flexible insulating material is wound a plurality of times around itself and around at least a portion of the insulating block, and another portion of the insulating block is attached to at least the outer edge of the outer layer of the plurality of layers of said flexible insulating material at said one end of the container.




Preferred further the insulating foam material is of closed-cell low-density polyethylene.




Preferred further at least one of said plurality of layers is attached to the block by heat-bonding, or by adhesive, or by the use of adhesive tape.




Preferred further a strip of adhesive tape lapping over both said outer edge and a portion of the insulating block all the way around the block attaches the sides of the container to the block.




Preferred further the container includes closure means for closing the other end of the container.




Preferred further said closure means comprises a further insulating block to be attached to the sides to close the other end of the container.




Preferred further the transport container contains dry ice and a product to be transported in the transport container.




Preferred further the closed cells in at least the inner layer of the plurality of layers of the sides of the container are pressurised and expanded in the plane of the inner layer by the carbon dioxide gas sublimed from the dry ice.




The present invention also in a transport which has been used for transporting a product and has contained dry ice, wherein any closure means has been opened, the block has been removed, the sides have been flattened and at least the inner layer of the plurality of layers of the sides of the container has been thinned.




Other preferred features of the invention will be apparent from the following description and from the subsidiary claims of the specification.











BRIEF DESCRIPTION OF THE DRAWINGS




The invention will now be further described, merely by way of example, by reference to the accompanying drawings, in which:





FIG. 1

is a perspective view of a transport container according to a preferred example of the invention, including its closure;





FIG. 2

is a cross-sectional view taken on the plane


2





2


on

FIG. 1

;





FIG. 3

is a cross-sectional view taken on the plane


3





3


on

FIG. 1

; and





FIG. 4

is a view similar to

FIG. 3

, but showing a modification of the preferred example.











BEST MODE OF INVENTION




Referring initially to

FIGS. 1-3

in the preferred example of the invention, a rigid circular disc


10


some 12 mm thick of polyethylene foam is glued coaxially on one side of another disc


11


of the same foam but of larger diameter to form a block


12


of T-shaped cross-section for a transport container


13


. The projection of the edge of the larger diameter disc


11


beyond the edge of the smaller diameter disc


10


constitutes a flange


14


. If required, the block


12


can be formed integrally in the same shape as that just described.




A single sheet


15


of flexible low-density polyethylene closed-cell insulating foam material as one edge


16


wound around the edge of the disc


10


and seating against the flange


14


. When the edge


16


of the sheet


15


has been wound all of the way around the edge of the disc


10


, it has returned to its starting point


17


, and winding then continues around the outside of the already-wound sheet and many more times to build up a multi-layered roll


18


of approximately circular cross-section of a plurality of layers of the sheet


15


of flexible insulating foam material. The roll


18


forms the sides of the transport container


13


.

FIGS. 2 and 3

show eight layers in the multi-layered roll


18


, but either more or less layers can be used.




The last layer is approximately flush with the edge of the disc


11


and is attached to it by a length of adhesive tape


19


extending around the edge of the disc


11


and also lapping over the outer edge of the roll


18


. The tape


19


is shown in

FIG. 2

only. Alternatively the edge


16


of the sheet


15


is attached by bonding to the edge of the disc


11


and the flange


14


, and the edges


16


of each of the layers of the roll


18


are bonded together and to the flange


14


. Bonding is achieved by adhesive or by heat sealing using a jet of hot air at a temperature of greater than 120 degrees Celsius. The block


12


closes one end of the container


13


. The other end


19


of the container


13


is open, and the adjacent edges


20


of the layers of the sheet may be bonded together if required.




The block


12


and the roll


18


attached to it are inserted in a heat-shrinkable polyethylene pressure envelope


26


with the block


12


in the closed-end of the envelope


26


and the wall of the envelope


26


extending along the roll


18


and tucked at


27


into the end


19


of the container. The envelope is omitted from

FIG. 1

, but shown in

FIGS. 2 and 3

. The polyethylene envelope


26


is initially a loose fit over the block


12


and the roll


18


as shown in

FIGS. 2 and 3

for clarity, and is subsequently heat-shrunk to apply pressure to grip tightly onto the roll


18


and underneath the block


12


, principally to reinforce the attachment of the block


12


to the roll


18


during the filling of the container


13


and during its subsequent handling and transport. The envelope


26


also reinforces the end


19


of the container


13


and the adjacent edges


20


of the layers of the sheet


15


. The part


27


of the envelope


26


inside the roll


18


does not shrink, but remains highly flexible.




It will be appreciated that all of the components of the transport container


13


described thus far, ie. the block


12


, the roll


18


and the envelope


26


, are made of polyethylene, which facilitates recycling and disposal of the container


13


after use, but if desired the pressure envelope


26


may be of a different material, for example an elastomeric material.




The container


13


is provided with a closure


28


, shown in

FIG. 1

only, which is of the same construction, shape and size as the block


12


. Thus the closure


28


comprises a large diameter disc


29


which fits as a cap on the end


19


of the roll


18


, and a coaxial small diameter disc


30


which fits snugly into the end


19


. The projection of the large disc


29


beyond the small disc


30


constitutes a flange which seats on the envelope


26


where it passes over the edges


20


of the layers of the sheet


15


.




In use the transport container


13


can be stood on end on the block


12


in a stable position to be filled, or can be filled lying on its side if this is convenient, the combination of the block


12


, the multi-layered roll


18


and the pressure envelope


26


giving the container


13


substantial rigidity. The closure


28


is then fitted in place and secured as required, for example by adhesive or by adhesive tape around the container lapping over the adjacent edges of the closure


28


and the envelope


26


. The container


13


can be labelled for shipping or put in a labelled shipping bag.




The contents of the transport container


13


may vary between the following types, as follows:




1. For a cold chain product to be kept as cold as possible during transport, the pre-chilled product is placed in the container


13


with the desired quantity (perhaps two Kgs) of “dry ice”, which is frozen carbon dioxide, in granulated, sliced or chunk form.




2. For a cold chain product to be kept cool, but not frozen, for example at 0 to 8 degrees Celsius, the pre-chilled product is placed in the container with a closed shell of flexible low-density polyethylene closed-cell insulating foam which contains a refrigerant. The refrigerant may be dry ice or a frozen ice mat of polyethylene sheet having pockets containing a frozen aqueous solution of polyethylene glycol. The refrigerant keeps the product cold for a long time, but the insulation of the shell between the refrigerant and the product stops the product from being chilled too much by the refrigerant.




3. For a warm product, the product is placed in the container on its own, or wrapped in additional insulation, or with a closed shell of flexible containing a warmed ice mat of the same construction as described above, but heated to, for example, 20 to 30 degrees Celsius.




When dry ice is used as a refrigerant, this sublimes to carbon dioxide gas at a substantial pressure which percolates molecularly into the closed cells of the polyethylene foam and any layer-to-layer spaces in the roll


18


where it chills the cell walls to its temperature. The carbon dioxide gas is also believed, without prejudice to the present invention, to pressurise and expand the cells of at least the innermost layer of the roll


18


. The outer layers of the roll


18


and the envelope


26


keep the expanded cells within the original thickness of the layer concerned, so that the expansion of the cells is also believed to be two-dimensional in the plane of the layers concerned, and to damage the cell walls. When the dry ice has sublimed away, that inner layer or layers is found to have lost most of its substance and resilience and to be thinner than it was, which reduces the bulk of the container for disposal or recycling.




The used container is readily recycled or disposed of because the block


12


can be quickly be detached from the roll


18


by slitting the envelope


26


around the block, and then breaking the attachment between the block


12


and the roll


18


, followed by flattening the roll


18


. This is readily done even if the roll contains a polyethylene foam shell or a polyethylene ice mat; all components are of polyethylene. The thinning of at least the inner layer of the roll


18


also reduces the bulk of the container prepared for recycling.




It will be appreciated that polyethylene foam is inexpensive in comparison with fabricated polystyrene, gives good protection from mechanical shock and poor handling, and is easy to recycle.




Referring now to

FIG. 4

of the drawings, in a modification of the preferred example, the block


12


described above has been modified to be a rectangular block


32


which has its corners rounded off at


33


.




The block


32


has a substantially rectangular cross section rather than a T-shaped cross section like block


12


.




The single sheet


15


described above has one edge


15


wound around the edge


34


of the block


32


from a starting point


35


, many times around the block


32


and then around itself to build up a multi-layered roll


36


of approximately rectangular cross-section, as clearly seen in FIG.


4


. The edge


16


is attached to the block


32


by adhesive, or double-sided adhesive tape, or by the use of a hot-air gun as the winding proceeds, and this bonding continues after the starting point


35


has been passed to bond each successive layer of the multi-layered roll


36


to its preceding layer. Such bonding also takes place at the edge of the sheet


15


opposite the edge


16


and the block


32


to secure the roll


36


together.




The block


32


and roll


36


are inserted in a pressure envelope (not shown) in the same way as in the preferred example, which stops the block


32


from being pushed out from the end of the roll which it closes. The envelope is preferably of polyethylene and is heat-shrunk in situ to apply pressure to the block


32


and roll


36


.




When the transport container of this modification has been filled with the product to be transported and any refrigerant that is required, it is closed by having its end opposite the block


32


pressed together in a linear closure, and is held in place by a strip of double-sided adhesive tape just inside and around that end.



Claims
  • 1. A transport container comprisingan insulating block; a plurality of layers of flexible insulating foam material forming sides of the container and mounted on the insulating block, which closes one end of the transport container; a heat-shrunk pressure envelope that applies pressure around the exterior of the sides and the block.
  • 2. The transport container according to claim 1, wherein the heat-shrunk pressure envelope is a heat-shrunk polyethylene envelope.
  • 3. The transport container according to claim 1, wherein the insulating block is formed from stiff polyethylene foam.
  • 4. The transport container according to claim 1, wherein sides of the plurality of layers of flexible insulating foam material comprise at least one sheet of said flexible insulating foam material wound a plurality of times around itself to form said plurality of layers of flexible insulating foam material.
  • 5. The transport container according to claim 4, wherein said at least one sheet of said flexible insulating foam material is wound a plurality of times around itself and around at least a portion of the insulating block.
  • 6. The transport container according to claim 4, wherein at least a portion of the insulating block is attached to at least an outer edge of an outer layer of the plurality of layers of flexible insulating foam material at said one end of the transport container.
  • 7. The transport container according to claim 5, wherein said at least one sheet of said flexible insulating foam material is wound a plurality of times around itself and around at least a portion of the insulating block, and another portion of the insulating block is attached to at least an outer edge of an outer layer of the plurality of layers of flexible insulating foam material at said one end of the transport container.
  • 8. The transport container according to claim 1, wherein the flexible insulating foam material is of closed-cell low-density polyethylene.
  • 9. The transport container according to claim 8, wherein at least one of said plurality of layers of flexible insulating foam material is attached to the insulating block by at least one of heat-bonding, adhesive, or adhesive tape.
  • 10. The transport container according to claim 5, wherein a strip of adhesive tape configured to over both said outer edge of an outer layer of the plurality of layers of said flexible insulating foam material and a portion of the insulating block all the way around the insulating block attaches the sides of the transport container to the insulating block.
  • 11. The transport container according to claim 1, further comprising closure means for closing the other end of the transport container.
  • 12. The transport container according to claim 11, wherein said closure means comprises a further insulating block configured to be attachable to the plurality of layers of flexible insulating foam material to close the other end of the transport container.
  • 13. The transport container according to claim 1, wherein the transport container is configured to transport dry ice and a product to be transported.
  • 14. The transport container according to claim 1, wherein the closed cells in at least an inner layer of the plurality of layers of the flexible foam insulating material forming the sides of the transport container are pressurized and expanded in a plane of the inner layer by carbon dioxide gas sublimed from the dry ice.
  • 15. The transport container according to claim 1, wherein the flexible insulating foam material is of closed-cell low-density polyethylene, and the transport container is configured to transport dry ice and a product to be transported.
Priority Claims (1)
Number Date Country Kind
9815474 Jul 1998 GB
PCT Information
Filing Document Filing Date Country Kind 102e Date 371c Date
PCT/GB99/02225 WO 00 3/16/2000 3/16/2000
Publishing Document Publishing Date Country Kind
WO00/03931 1/27/2000 WO A
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Number Name Date Kind
2803368 Koch Dec 1957
3139206 Matsch Jun 1964
3472568 Southwick Oct 1969
3888557 Anderson et al. Jun 1975
4377075 Russo Mar 1983
4862674 Lejondahl et al. Sep 1989
5009952 Klepsch et al. Apr 1991
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Number Date Country
3743372A Jun 1989 DE
WO 8001791A Sep 1980 EP
0157751A Oct 1985 EP
2419884A Oct 1979 FR
610559A Oct 1948 GB
1403771A Aug 1975 GB
1482325A Aug 1977 GB
2235523A Mar 1991 GB
2262155A Jun 1993 GB