CA1291073C - Thermal packaging assembly - Google Patents

Abstract

CRYOPAK CORPORATION
LIN HENRY

THERMAL PACKAGING ASSEMBLY

ABSTRACT OF THE DISCLOSURE
A thermal packaging assembly comprises a plurality of capsules of non-rigid material each containing a thermal controlling , agent which can maintain a predetermined temperature range for an extended period of time. The capsules are packed around one or more items which are to be maintained in a controlled temperature environment over an extended period, and are designed to also provide cushioning of the or each item against shocks. The capsules may be used with a suitable insulated container or may be provided in a continuous sheet in bubble pack form to be wrapped around items to be packed.

Description

9~073 .

~ERMAL PACXAGII~. ASSE~IBLY
:
BAC~GP~O~ 1D OF T~}E INVENTION
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The present invention relates to thermal packaging assemblies for any items which are tQ be packed in a .~hermally controlled environ-nent for extended periods of time, .such as foodstuffs, beverages, plants, other biologica} ..mate;ials, medicines or other chemicals, temperatu.re sensitive electronic equipment, tissue ~p~cimens,.and so on.
.. The u~se of re~rigerants to keep items or products cool over extended periods of. time. is ~idespread, both for transportation of heat sensitive or heat damageable products and for long term storage of such products. Refrigerators and refri~erated transport systems can be used on the large scale for storage and transportation, but less massive and expensive coolant systems are required for smaller scale purposes, for example short haul delivery systems, airline transportation, and home and recreational cooling of foods, beverages and the like.
The packing of temperature sensitive products such 2s foodstuffs, pharmaceuticals, plants, biological materials . and the like in ice or dry ice to maintain their temperature over a prolonged period of time is well kno~7n and has been used extensively for many years. For example, the general public ~idely uses insulated containers or cool boxes packed ~ith ice to maintain foodstuffs and beverages cool when camping, travellinq vr on picnics and the like.
Conmercially, ice is used in packing foodstuffs, flowers, HN~'APA . I 2 3 ]

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plants and the like for transportation and storage until sold or until placed in a refrigerator in a store, for example. ~n the.medical field, ice is used to reduce trauma, swelling and pain from injuries of all kinds, and is also s ~used in ~ransportation and storage of blood, tissue, organs, pharmaceuticals and the like. Ice or dry;ice is also used in *ransport and use of heat sensitive equipment or ~: instruments, and ice baths and controlled chemical reactions; ~
10 ; `:. The use of ice or dry ice as a coolant material serves ~_. a preservative in many -cases and inhibits the ~rowth ~of many harmful micro-or~anisms. Another cool~nt in common use, ; particularly in cooi boxes. used for recreational purposes, is the so-called nblue icen, which is a block or bag of 15 coolant material which is frozen solid before being placed in a container such as a cool box to maintain foodstuffs or drinks in the container cool for extended periods of time.
The major drawback to the use of ice as a coolant - material is that it melts. The space taken up by the ice when melted ~ill be ~ess than when it is frozen, so that it will no longer be an effective packing material. The melted ice is easily contaminated by microorganisms and, since it will be in intimate contact with the products it is protecting, these are also liable to become contaminated.
They may also be damaged by getting wet. If the products to be protected cannot tolerate ~etness, they must be protected from melted ice in some way, for example by the use of raised shelves in cool boxes for placing foodstuffs above the level of the ice or by some sort of waterproof packaging before the~ are packed in the ice. The melted ice will also [HN~APA.I23~

~29~073 allow the products to move or slosh around in the ~ontainer, risking damage by impact with the walls of the container. The container itself must also be waterproof.
Dry lce has similar problems, in that it is conver~ed into CO2 with time and thus tha gas must be dissipated and the product will no longer be packed against movement in its container. Both water and dry ice can be used only once, adding to the expense of thermal storage.
In contrast, blue ice can be used repeatedly by refreezing the contents of the bag or block, but is brick hard when fro~en into a solid block and is unable to conform to the shape of products to be kept cool in this state. Thus it does not maintain good contact with unevenly shaped products over a large portion of their surface area. It will become soft and pliable as the material melts within the bag.
Neither lce nor "blue ice" is shock absorbent when activated or frozen and they are therefore not ideal packaylng materials, partiularly of relatively fragile i~ems or articles of complex and non-uniform shapes.
SUMMARY OF THE INVENTION
Accord:Lng to the present invention there is provided a thermal packaging assembly, comprising an outer container;
a plurality o~ separate reusable capsules in said each container each capsule comprising a continuous outer skin of flexible plastics material and a ~hermal conkrolling agent comple~ely filling the capsule, the agent being a liquid in a predetermined temperature ranye, and freezable into a solid phase ~,~

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prior to use in the packaging assembly;
sa:id outer contai.ner comprising means for packing the capsules around one or more items to be packed, the container having an opening for receiving the capsules and items to be packed;
the capsules each being of identical shape and dimensions and each having opposed sloping, curved outer surfaces for resisting close packing against adjacent capsules in the packaging ass~mbly and for forming air gaps between each capsule and the next adjacent capsules;
the capsules comprising means for cushioning an item or items around which they are packed, means for absorbing shocks by moving freely relative to one another and means for maintaining a predetermined temperature range for an extended period of time.
: The invention further provides a thermal packaging material for wrapping around an item or items, comprising, a con~inuous sheet containing a plurality of rows of adjacent reu~able capsules, each containing a thermal controlling agent t which completely fills the capsules, each row beiny separate fromthe next adjacent row by a first set of spaced seal lines and the : capsules in each row belng separate ~rom one another by a second set of spaced seal lines perpendicular to the first set;
each capsule having a generally rectangular outer periphery and opposing curved outer surfaces on the upper and lower face of the sheet;
the thermal controlling agent being a li~uid in a : predetermined temperature range and frozen into a solid phase having malleable characteristics prior to use in the packaging ~ 2~
-4a- 7401~-1 assembly; and the sheet belng selectively bendable when the ayent is solidified along both sets of perpendicular seal lines to completel~ wrap around an item to be packed and an outer enclosure releasably enclosing said sheet.
The invention additionally provides a thermal packaging assemhly, comprising:
a plurality of pillow-shaped hollow capsules of flexible plastics material each containing a reusable thermal controlling agent elected from the group consisting of an aclueous solution of 3% by weiyht polyethylene glycol having a molecular weight in the range from 7,000 to 9,000 which completely fills the capsule leaving no air gaps, and a eutectic solution having a liquid phase and at least two solid phases, the agent being a liquid within a predetermined temperature range;
enclosing means for packing the capsules around at least one item to be packed so that the item is enclosed by and in direct contact with the capsules the capsule being within sald enclos:Lng means;
the opposed sloping outer surfaces of the capsules comprising means for resisting close packing and for leaving air gaps between adjacent capsules and between the innermost capsules and the item to be packed.
According to another aspect of the invention there is provided a method of packing one or more items to maintain a predetermined temperature range for an extended period of time and to cushion the item or items against shocXs, comprising the steps o~:

~9~0~3 -4h~ 74018-1 taking a plurality of reusable capsules each ~ontaining a thermal controlling agent which completely fills the capsules and which is a liquid within a predetermined tamperature range and has a solid phase and freezing the capsules until the li~uid in the capsules solidlfies; and packing the capsules in a container arouncl at least one item to be packed SQ gaps between the opposed, curved outer surfaces of each capsu].e and the next adJacent capsules and the capsules are free to move relative to one another to absorb shocks, the capsules maintaining the packed i~em in a pradetermined temperature range for an extended period of time and cushioning the item against shoeks during and beyond the extended period of time; and subsequently reusing the capsules by refreezing them prlor to packing them around other items to be packed.
- Useful thermal controlling agents include:
'~ (a) an aqueous solution of 3% by weight o~
polyethyleneglycol having a molecular weight in ~he range of 7,000 to 9,000;
(b) 40% propylene glycol, 50% isopropanol and 10% deionized water; and (c) an aqueous solution of 30% by weight of polyethylene glycol having a molecular weight in the range of 7,000 to g,ooO.
According to the present invention a thermal packaging assembly is provided which comprises a plurality of capsules of non-rigid material each containing a thermal controlling agent for maintaining a predetermined temperature range for an axtended period of time, and a means for containlng or packing the capsules -4c- 74018-1 around one or mor~ ikems to be maintalned ln the predetermined temperature range for a certain time period. The individual capsules are of relatively small dimensions as comparecl to the item or total volume of ltems to be packaged, and since they are packed relatively loosely around the item they will be shock absorbing to a certain extent to cushion the packed item ayainst damage, while at the same time protecting against change in temperature for extended periods of time.
The capsules may be packed in a suitable insulating outer container, and they may be separate or connected together in the form of a sheet of bubbles with an interconnecting web. They may be of any suitable shape, the shape preferably being chosen so that the capsules resist compaction and will be free to move relative to one another when packed around one or more items so as to provide a relatively good cushioning e~ect. They may, for example, be of a shape similar to the known poly foam pellets used for packaging, or o~ arcuate, ovoid, tubular or other shapes which will resist close packing, i.e. tend to pack ~oge~her loosely with yaps between adjacent capsules. In a preferred embodiment they are pillow shaped.
The packagin0 assembly of this invention is therefore an improvement both over known coolants such as ice, dry ice or blue ice, and over known packaging materials which have no thermal controlling properties.
The thermal controlling agent contained in the capsules is preferably a refrigerant although it may be desiyned to hold items at any chosen tempera~ure, i.e. even at ~emperature~ above the ambient or surrounding temperature. In a preferred embodiment ~29~73 -4d- 7401g-1 o~ the invention the agent i5 a eutectlc solution which has the capacity to absorb or release heat with little or no chanye in temperature whlle in the process of changing ~rom one physical state to another, e.g. solid to liquid or vice versa. The capsules ~.~9~LO'73 must first be charged or frozen to the phase change temperature or lower. They will then ~aintain items around which' they are packed in a temperature controlled environment for a time interval dependent on the number of capsules used, the insulating properties of any container in ; which they are packed, and ~he s4rrounding ambient temperature.
' h~ater is one example of such an agent where it will ~change from~ a liquid to a solid stat;e at the` precise 'tempe'r'ature of 32 F (~he phase change temper~ture). In the e~er;~ embodiment of the invention the agent comprises a mixture of two or more substances which are miscible as - liquids but which have a lower free~ing point when combined than ei'ther of the two sub'stances separatelyO The point at lS which both substances solidify is kno~ln as the eutectic poin't.
In one example of the invention the eutectic solution is a solution of a eutectic salt or compound which is formulated to provide good energy storage capability at a given operating temperature. Such compounds may be formulated for storage capabilities at a wide ~ariety of different temperature ranges, and may be used for hot or cold storage according to the eutectic point of the chosen eutectic compound or compounds in the capsules.
The individual capsules or sheet of capsules may be used alone or in combination with dry ice, for example. This avoids the problems of using dry ice alone while allowing its effective cooling period to be prolonged. The capsules may be designed for any specific operating temperatures by suitable choice of the eutectic compound or compounds.

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, In one particular embodiment the capsules,are designed to exhibit a similar cooling temperature range to ice. Xn this example the. thermal storage material in each capsule is 'a'solutibn of ammonium sulfate, calcium chloride, or other 5' .inorganic salt, with the temperature at the eutectic point of the material, i.eO the point at which the solution . ,changes''phase, being dependent on the particular salt used '''in'the material. The capsules may also be designed to hold produc'ts .at,,higher temperatures with suitable choice of the .thermal s.torage material. ' ' , .. ..
BRIEF DESCRIPTION OF T~E DRAWING5 . .
' :, The present invention will be better- understood from the :taken in conjunctio~ with the accompanying drawings in which like reference numerals refer to like parts and in whi ch: .
' Figure 1 shows a s~de elevation view of a thermal packing assembly according to a first embodiment of the present invention, partly cut away to show a suitable item to be packed and thermally protected embedded in the packing material.
Figure 2 is a top plan view of a particular configuration of one of the capsules o the packing . assembly;
Figure 3 is a side elevation view of the capsule o~
Figure 3.
; Figure 4 is an enlarged sectional view taken on the lines 4-4 of Figure 3;
Fisures 5 to 9 are perspective views of various other possible shapes for the capsules; and [HN~ P~.I23]

1.~9~ 3 igure 10 shows an alternative embodiment of the thermaI packing assembly according to the present invention.
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. DESCRIP~ION OF TEIE PREFERRED EMBODIMENTS
Figure 1 shows a first embodiment of a thermal packing assembly according to the present invention, in which a : plurallty of capsules 10 con~aining a thermal controlling agent o'r r~f~'igerant are packed in a container 14 around an item 16 'to b'e thermally protecte'd.
i The 'item ~6 may be anything of a perishable ~r te'mper~t~re damageable nature~ for example~ or anything ' which i's to be kept at a controlled temperature for any ; reason, and more than one item may be packaged in the capsules. The item o~ items 16 may, for example, be ~oodstuffs, beverages, plants, biological materials, tissue samples,' chemicals~ medicines, or live creatures such as bait ~or fishing. The container may be of any suitable shape and dimensions according to the item or items to be packed, and is preferably insulated.
As shown, the individual capsules are each of dimensions much smaller than those of the ;te~ or total volume of items to be packed, so that the capsules packed around the item will have some cushioning effect to protect ' the item against shocks and can also contact most of the outer surface of the item even if it is of a non-uniform or irregular outer shape. The capsules may be shaped so that they resist compaction when packed, iOe. so that they will tend to leave gaps 18 between adjacent capsules. This will enhance the cushioning effect since capsules will be able to ~0 move relative to one another to resist or absorb shocks.

1 I~Nl~ APA, 12 3 ~

~X9~(173 -8- 7~018~1 The capsule dimensions are preferably o~ the order of one square inch or less but may be larger le.g. 3 s~uare inches) for larger scale packing and further may have dimensions of up to 3'~3"xl/4", for example. The smaller scale capsu:les will be filled with 0.5 ml to 2 ml of refrigerant liquid, with largex scale capsules containing up to 20 ml of refrigerant.
Figures 2 to 9 show some of the many possible capsule shapes. Figures 2 to 4 show a first possible configurakion in which each capsule 20 is tubular with its opposite ends sealed.
Such capsules may be manufactured from lengths of tubing filled with a suitable refrigarant 12 (See Figure 4), which are sealed at suitable spaced intervals, and then cut to ~orm individual capsules. In one specific example of this type of capsule the capsules were made of 1 inch segments of polyethylene tubing having an outside diameter of 1/4" and a wall thickness of 1/16", filled with approximately 0.5 ml of refrigerant solution. However these specific dimensions may be changed according to the particular applications for which the capsules are to be used.
Figures 5 to 9 show some of the many possible alternative configurations for the capsules. In Flgure 5, the capsule 30 is of generally square or rectangular outline and of pillow-like form.
In Figure 6 the capsule 40 is of curved of S--like shape, similar to the shape of foam pellets commonly used for packaging.
Figure 7 shows another alternative capsule shape 50 which is of a tubular form with enlarged and portions. Figure 8 shows a capsule shape 60 of curved, C-shaped form, and in Figure 9 the capsule 70 is of a star or flower-like form. In each case the capsules may be formed, ~ . ~xs~)73 for example, by moulding the individual capsules from a suitabl-e material and then filling with the refrigerant 12.
- The 'capsules may be manufactured in any suitable manner, including blow moulding, vacuum moulding, machine forminq or 'extruding tubing which is suitably sealed and cut, forming tubing from a continuous film and suitably sealing, filling with refrigerant~ and cutting into : individual capsules, and die moulding of individual capsules and. filling with refrigerant.' ; ` The individual capsules are formed with an outer skin of a suitable non-rigid or flexible material which is cho~en according to the operating temperature of the'assembly in which the ca'psules are to ~e used and the refrigerant which the capsules are to contain. T~e capsules are preferably of a s'uitable plastics material such as low temperature melting polyethylene, PVC~ Teflon ~ (Registered Trademaxk), polypropylene, polycarbonates, nylon and the like.
' Each capsule is filled wit~ a refrigerant 12 which is chosen according to the desired operating temperature.
Although the assembly will normally be used to maintain a temperature controlled environment below ambient temperatures, i.e. as a cooling assembly, it may also be designed for use at temperatures higher than ambient, i.e~
;for heating or maintaining items at a raised temperature, with suitable use of the agent 12 within the capsules.
- The refrigerant 12 is pref~rably a material ~hich will change from one physical state to another, i.e. liquid to solid or vice versa, at a predetermined temperature, called the phase-change temperature. The capsules must first be charged, or cooled to a temperature at or below the PA.I23]

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predetermined temperature. They must normally be charged at a temperature -20C below the holding temperature for periods of between 16 and 20 hours, depending on the total volume of capsules to be charged and their phase change temperature. The capsules will then stay in a certain temperature range for an extended period of time to hold the : temperature of an item or items around which they are packed - for a time~ dependent on the insulating properties of any QUter contaiher, the number and weight of the capsules used, a~d ~e surrounding ambient temperature.
According to t~e ch~ice of refrigerant mat~ri-al ~he thermal packing assembly can hold products at various pre-selected temperatures from -13 C ~9 F) to 25 C (77 F) for periods ranging from a few hours up to nearly 500 hours, according to the number of capsules used and the properties of the surrounding insulated container. With suitable choice of the controlling agent it may even be possible to provide temperature control at any desired temperature in a range ~rom -60 C to 66C. The capsules are most efficient when used with a well insulated container.
The thermal controlling agent or refrigerant has the capacity to absorb or release heat with little or no change in temperature while in the process of changing from one physical state to another, i.e. liquid to solid or solid to liquid. It is this property which makes ice such a good refrigerant. h'here the refrigerant 12 is water, the capsules ~ill first be frozen at 32 F. The ice must then absorb 144 BTU's of heat energy before it becomes liquid again.
Although water is a possible refrigerant for the capsules, in one preferred embodiment the refrigerant is a [H~ APA.I23~

~ ~9~0~3 ; eutectic solut~on, or.a mixture of two or more substances which has a lower freezing point, ~nown as the eutectic point, than eIth.er of the two ~ubstances taken individually.
The solution on cooling will transform from a single liquid 5 ' phase to two or more solid phases at the eutectic point.
This is known as a eutectic reaction and may be used to ..maintain a chosen temperature range in a manner si~ilar to, or ev.en. m.ore efficient than ice. The solution may, for example, ~omprise a mixture or solution of an inorganic salt 10 :.in .water; The salt may, for example, be chosen from the L~ilowing class: So~ium,calcium,ammoniumror potassium . chloriàe; ammonium,magnesium, or sodium suifate;- potassium : or sodium nitrate, among others.
The refrigerant or cooling agent is formulated to ~aintain specific temperature ranges under controlled conditions, and a range of different capsules containing different agents may be provided for various different applications.
. Some specific examples of e~tectic and other refrigerants are given below, although other refrigerants or temperature controlling agents can clearly be designed for operation at various temperatures. The refrigerants used are non-toxic and non-corrosive materials, and preferably have ~ high boiling points and low expansion coefficients in both 25 the solid and liquid phase. The refrigerants are preferably of high density with a heat of fusion (heat required for change of state at phase change temperature) of over 100 BTU ' s per pound~

N~YAPA.I23]

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)73 ~ _mpl~ l : The capsules are filled with an 11 ~ by weight aqueous sDlution of ammonium sulf~te. The.capsules are charged by storing' for lO to 16.hours (depending on their total mass) S at a temperature of -4 F , for example, in any suitable refrigerator or cooling assembly. The eutectic or freezing : .. point of the.soluti'on is -3.18 C. The ammonium sulfate may .. be'..replaced'with calcium chloride, for example, or other suitable 'lnorganic salts. The capsules will maintain a lO '.constan~ temperature over a similar period to an eauivalent ~lu~e of ice. With a surrounding ambient temperature of '21 C a weight of 5 lbs of the capsules coptained in a volume of . 432' cu. inches within a container having 3 inch thick uret~ane walls can hold or ma;ntain refrigerator ~emperatures in the range from 2 to 8 C for up to 103 hours, which is equivalent t'o a similar volume of 'ice or blue ice while not having the disadvantages of such cooling agents, i.e. melting, non-cushioning, and so on.
.

Ex3mPle 2 In this example the refrigerant is the following mixture:
200 gm polyethylene glycol (PEG) 20g wt. over volume 28.392 gm sodium phosphate diabasic 0.15 molar with pE3 adjusted to 7.2(Na2HPo4~7E~20) 19.8 gm ammonium sulfate 0.15 molar in distilled water.
The eutectic point of this mixture is -2 C. The holding temperature may be increased or decreased by decreasing or increasing, respectively, the amount of ammonium sulfate or PEG.

lE~NR~APA~I23]

. Capsules containing this refrigerant contained under the same conditions as the capsules in Example 1 can ,maintain refrigerator like temperatures for equivalent ' periods of time and have the additional advantage that the added PEG will prevent the mixture from completely solidy,~ying even when frozen. Thus the ,capsules will still be,malleable, or semi-hard, when charged and will therefore have i~'prov.ed cushioning characteristics.
:. ;, .. .
a-mDl e ;~ ' . - ., .The'reri~erant in this example compris,es N-Tetradecane (CH3(CH2)12CH3). Th,is has a phase change ,temperature of 4.4 C and under similar conditions to the capsules in example 1 capsules co*taining this refrigerant can hold their 15. ~emperature for about 76 hours and thus have thermal insuiating properties for equivalent periods of time.

~xamPle ~
In this example the capsules contain ethylene glycol 20 400, which has a phase change temperature of -1207 Q C. miS
material ~ill still be malleable when frozen and thus the capsules ~ill have improved cushioning characteristics. The capsules must be charged at lower temperatures than the previous examples, for example at -20 C for up to 16 hours depending on the total mass to be charged. Under equivalent conditions to the previous examples capsules containing this refri~erant will stay frozen for up to 49 hours~ and can m~intain a lower temperature environment than the previous examples which maintain refri~erator like temperatures.

IHNR~'AP~.I23~

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ampl e ,~ , .
In this example the capsules contain N-Hexadecane, which has a p~a~e change temperature of 25 C. This may be used~ for example, to maintain temperatures higher than the ~ 5 surrounding ambient temperature over extended periods of : time.
; The above five examples are compared in the following . table over .diff~rent ambient temperatures, with the capsules in each case.being pre-charged to at or below the phase .change temperature for a predetermined period of time and ~e~ng contained as described above in connection ~ith . Example l. The tabie shows the theoretical holding time in ; hours which may be achieved by.the different controlling agents in each example.
15 ....... . . TABLE
Average Ambient Temperature ( C3 CAPS~LE -13 -6 4 21 32 38 43 : 20 .OPERATING
TE~IP ( C) HOLDING TIME IN HOURS
-13 (Ex.4) 393 311 125 62 46 41 37 _3 (Ex.l) 155 621 340 103 70 61 53 0 (Ex.2) 120 319 478 101 66 56 49 4 (Ex.3) 64 129 _ 86 51 43 37 25 (Ex.5) 38 53 78 412 - - _ The average holding time for any thermal packing assembly can be estimated in advance given the surrounding ambient temperature and the mass of capsules to be used, 1 HN~ APA . I 2 3 ]

~ ~''3~)73 together with the thermal conductivity of any surrounding insulating container. ~he holding time will be equal to the heat availabie . divided by the heat loss, which will be dependent on the total volume and the thermal conductivity 'properties of the container. Thus anyone with a specific packaging and thermal control problem will be able to estimate in advance the probable amount of capsules needed for a . ~articular length of time, and the most desirable thermal controlling agent to use in the capsules. ~Capsules cpntaining di~ferent thermal controlling agents may be mixed together in certain case~ to prolong the cooling per;o~s, ` for example.
Thus the packing assembly described above has the advantage of both cushioning items pac~ed aqainst shocks or damage ~hile maintaining them in a predetermined temperature range over extended periods of time. The amount of capsules needed znd the type of refrigerant to be used can be calculated in advance according to the items to be packaged, the expected ambient temperature, and the length of time they are to be maintained in the predetermined temperature ~ range, which will typically be refrigerator temperature or -~ lower. Even when the capsules reach ambient temperatures, they will still have some insulating properties to continue . to insulate the packed items to a certain extent, and will still be a good packaging material since there will be little or no change in the volume they displace when the material in the capsules changes phase.
The capsules may be used alone or mixed with anothr refrigerant. For example, in cases where dry ice (C02) ~ould otherwise be specified as a coolant, a mixture of dry ice [HNR~APA.I23]

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9 ~ ~ 3 -lb-with the capsules may be packed around the item or items to be refrigeratedr This would act both to prolong the cold generated by ~he dry ice and keep it away from direct .. . s contact with the item or items~ Some of the capsules themselves may also be filled with dry ice as the thermal controlling agent.
The material of the capsules is chosen such that the capsules will not st;ck or adhere to each other or adjacent surfacesr which is a problem with ice and similar- coolan~
materia1s. The capsules have a non-wetting and non-wettable su~face, so that condensation will be minimal and growth of mic~o-organisms on the surface will normally not be supported.
As described above the shape of the capsules can be ~hosen so that they resist compaction. Typically the percentage of compaction should be less than one fifth of the total volume in which the capsules are contained.
The capsules can be re-used any number of times simply by re-charging them once they have reached ambient temperature. The outer skin is flexible but fairly resistant to tearing. The capsules will therefore be relatively inexpensive, particularly when compared to ice and other single use coolant materials, and have a relatively long life.
If the capsules should by some chance be ruptured, the agent inside is chosen to be non~toxic, non corrosive, and w2shable with water. The material of the capsules themselves is also non-reactive, non-toxic, non-corrosive, and non-digestible.

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~'~9~L()73 . .
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' .The capsule~ may be used as described' above in a thermai packing assembly to transport or store ar.y delicate and/or temperat'ure sensitiYe items, such as perishable '.. f'oodstuffs, plants, -pharmaceuticals and so on. They may.be S used to store and/or transport frozen foods, biologicals and other Prozen materials for 20 to ~0 hours at temperatures of 20~ to -4C ~ith suitable choice of refrigerant in the : capsul.es~ .They may be used in place of ice or ~lue ice for recreationaI 'p-urposes to keep foods and drinks ~co~l on 10. picnicsi while camping,..or on other outings, for example.
Another.possible use is to keep bait cool when fishing.
. ''. 'The capsules of thîs invention may.also be used, for example, in ice baths for temperature control of laboratory chemica'l reactions , for protecting temperature sensitive 1-5. ~ilm, or for treatiny swelling or other injuries in the form of ice pac~s. Another possible use is in ice dispenser or stora'ge systems, where packs of ice for use in drinks and the like are stored prior to sale or use.
It can therefore be seen that the capsules of this invention are an extremely versatile, economical and efficient thermal controlling and packing material, which can be designed for packing any number of different types of items and for operating temperatures over a wide ran~e, both ' below and above ambient.
The capsules need not be contained in a rigid outer container, but may be enclosed around an item or items to be packed by any suitable means, for example as a flexible ~rapping.

[HN~AP~.I23]

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.. --1 ~--Figure 8 ~hows an alternative example of a thermal packing assembly according to the invention. In this example a plurality of capsules 80 containing a suitable refrigerant 82,which may be any suitable material as described above in connection with the previous embodiments, are interconnected in the form of a sheet ~4 of bubblè pack type material. The : shee~ 84 may be manufactured in a similar manner to standard -- bubble pack material, with each bubble or capsule 80 being filled with the refrigerant 82 in its liquid state. The capsules in the sheet may be of any suitable shape. The sheet will be pre-charged in the same manner as the individual capsules as described above, and then wrapped around an item or items to be packed. The wrapped sheet may be enclosed in an outer ~ontainer if desired, for added insulation, or it may be secured around the item to comprise the ëntire packing assembly.
Although some preferred embodiments of the present invention have been described above by way of example, it will be understood by those skilled in the field that modifications may be made which are within the scope of the present invention, which is defined by the appended claims.

[HNR~PA.123]

Claims (11)

1. A thermal packaging assembly, comprising an outer container;
a plurality of separate reusable capsules in said each container each capsule comprising a continuous outer skin of flexible plastics material and a thermal controlling agent completely filling the capsule, the agent being a liquid in a predetermined temperature range, and freezable into a solid phase prior to use in the packaging assembly;
said outer container comprising means for packing the capsules around one or more items to be packed, the container having an opening for receiving the capsules and items to be packed;
the capsules each being of identical shape and dimensions and each having opposed sloping, curved outer surfaces for resisting close packing against adjacent capsules in the packaging assembly and for forming air gaps between each capsule and the next adjacent capsules;
the capsules comprising means for cushioning an item or items around which they are packed, means for absorbing shocks by moving freely relative to one another and means for maintaining a predetermined temperature range for an extended period of time.

2. The assembly as claimed in claim 1, in which the capsules are pillow-shaped.

3. The assembly as claimed in claim 1, wherein the agent comprises an aqueous solution of 3% by weight polyethylene glycol having a molecular weight in the range from 7,000 to 9,000.

4. The assembly as claimed in claim 1, in which the agent comprises a solution of 40% propylene glycol, 50% isopropanol, and 10% deionized water.

5. A method of packing one or more items to maintain a predetermined temperature range for an extended period of time and to cushion the item or items against shocks, comprising the steps of:
taking a plurality of reusable capsules each containing a thermal controlling agent which completely fills the capsules and which is a liquid within a predetermined temperature range and has a solid phase and freezing the capsules until the liquid in the capsules solidifies; and packing the capsules in a container around at least one item to be packed so gaps between the opposed, curved outer surfaces of each capsule and the next adjacent capsules and the capsules are free to move relative to one another to absorb shocks, the capsules maintaining the packed item in a predetermined temperature range for an extended period of time and cushioning the item against shocks during and beyond the extended period of time; and subsequently reusing the capsules by refreezing them prior to packing them around other items to be packed.

6. A thermal packaging material for wrapping around an item or items, comprising:
a continuous sheet containing a plurality of rows of adjacent reusable capsules, each containing a thermal controlling agent which completely fills the capsules, each row being separate from the next adjacent row by a first set of spaced seal lines and the capsules in each row being separate from one another by a second set of spaced seal lines perpendicular to the first set;
each capsule having a generally rectangular outer periphery and opposing curved outer surfaces on the upper and lower face of the sheet;
the thermal controlling agent being a liquid in a predetermined temperature range and frozen into a solid phase having malleable characteristics prior to use in the packaging assembly; and the sheet being selectively bendable when the agent is solidified along both sets of perpendicular seal lines to completely wrap around an item to be packed and an outer enclosure releasably enclosing said sheet.

7. The packaging material as claimed in claim 6, wherein the sheet of capsules is formed from two opposed films sealed together along spaced parallel lines in two perpendicular directions to form separate capsules each having a rectangular outer periphery, each capsule being filled with a liquid forcing the outer opposed surfaces of that capsule outwardly to form a generally pillow-shaped capsule.

8. A packaging material as claimed in claim 6, wherein the thermal controlling agent is a eutectic solution having a liquid phase and at least two solid phases.

9. The packaging material as claimed in claim 6, wherein, the thermal controlling agent is an aqueous solution of 30% by weight polyethylene glycol having a molecular weight in the ranges from 7,000 to 9000.

10. A thermal packaging assembly, comprising:
a plurality of pillow-shaped hollow capsules of flexible plastics material each containing a reusable thermal controlling agent elected from the group consisting of an aqueous solution of 3% by weight polyethylene glycol having a molecular weight in the range from 7,000 to 9,000 which completely fills the capsule leaving no air gaps, and a eutectic solution having a liquid phase and at least two solid phases, the agent being a liquid within a predetermined temperature range;
enclosing means for packing the capsules around at least one item to be packed so that the item is enclosed by and in direct contact with the capsules the capsule being within said enclosing means;
the opposed sloping outer surfaces of the capsules comprising means for resisting close packing and for leaving air gaps between adjacent capsules and between the innermost capsules and the item to be packed.

11. The assembly as claimed in claim 10, wherein the capsule dimensions are in the range one square inch to three square inches, and the capsule thickness is of the order of 1/4 inch.