A PASSIVE TEMPERATURE CONTROL SYSTEM FOR TRANSPORT AND STORAGE CONTAINERS

Abstract

The present invention relates to the field of the transportation and storage of goods and to a passive temperature control system for such a transport and storage containers. The present invention seeks to provide a system that can enable goods to be securely and reliably transported and stored for limited periods within specified temperature ranges. Pharmaceuticals, proteins, biological samples and other temperature sensitive products, including food items, are regularly shipped in containers year round and are subjected to a wide range of temperatures. Though they are shipped in insulated containers and/or climate controlled environments, the temperature stability of the shipping containers can be significantly improved by utilising suitable phase change materials in an ordered fashion. The present invention provides a simple solution to the maintenance of temperature profiles for the transport and storage of temperature sensitive products.

Claims

1. A temperature controlled transport/storage container for transporting/storing temperature sensitive materials comprising: an outer insulating container having a top inner wall, a bottom inner wall and inner side walls; insulating means for insulating the cavity comprised of a lining disposed adjacent to the inner walls of the carton to define an insulated cavity; and a plurality of first and second temperature control panels for placement within the insulated cavity, adjacent to the means for lining the inner walls to define a payload volume; wherein the first and second temperature control panels include, respectively, first and second phase change materials, wherein the first and second temperature control panels have a major planar face, which major planar face is directed toward the payload volume.

2. A temperature controlled transport/storage container according to claim 1, wherein the temperature control panels are contained in sealed containers, the sealed containers being defined by one of a plastic bag, a blister pack, a sheet cellulose package, and a sealed polymer enclosure.

3. A temperature controlled transport/storage container according to claim 1, wherein the temperature control panels include at least one further phase change material.

4. A packaging system according to claim 1-3, wherein the first phase change material has a phase change temperature in the range of +25 C. to 20 C.

5. A packaging system according to claim 1, wherein the phase change materials are presented in the form of one or more of: plastic bags; polymer bags; blister packs; putty; and foam encapsulation particles.

6. A packaging system according to claim 1, wherein the phase change materials are presented in a container such as a cardboard box or a plastic pre-form.

7. A packaging system according to claim 6, wherein the phase change materials are thermally connected via a thermally conductive layer of material.

8. A packaging system according to claim 6, wherein for each side of the container there is a single temperature control panel, which retains a single phase change material.

9. A packaging system according to claim 6, wherein the phase change materials are thermally connected with each other via a thermally conductive layer of material applied to the container.

10. A packaging system according to claim 9, wherein the thermally conductive layer of material comprises a reflective coating.

11. A packaging system according to claim 1, wherein the container is manufactured from one of: cardboard, plastic sheeting, corrugated cardboard, and corrugated plastic.

12. A packaging system according to claim 1, wherein the means for insulating the cavity comprises one of or more of: a plastic foam; loose cellulose fiber; compressed cellulose fiber; multilayer insulation; fiberglass woven cloth; and fiberglass woven cloth impregnated with PTFE Teflon, PVF reinforced with Nomex bonded with polyester adhesive, and FEP Teflon, Mylar that is aluminized on both or one side.

13. A packaging system according to claim 1, wherein the means for insulating the cavity further comprises a reflective coating.

14. A method of packing a container for shipment comprising the steps of: a. obtaining a container; b. lining the entire interior surface of the container with insulator material; c. selecting a plurality of temperature control panels for placement within the insulated cavity, wherein the temperature control panels include generally planar packages one phase change materials arranged as, each planar package having spaced apart first and second major planes with edge faces connecting the first and second major planes; wherein the phase change materials provide distinct thermal characteristics; d. determining a temperature at which to condition a temperature control panel means with regard to the size of the container, the duration of transport/storage of the container, or the expected ambient conditions; e. placing the temperature control panel at the determined temperature in a temperature conditioning apparatus, whereby to ensure the temperature control panel is brought to the set temperature; f. placing the temperature control panels having been brought to the set temperature in the container whereby to define a payload volume wherein the at least two types of phase change material packages are arranged such that the load cavity is equidistantly separated with respect to each type of temperature control panel; g. placing a payload within the payload volume; h. placing a temperature control panel upon the payload and other temperature control means; and i. closing and sealing the container.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0025] For a better understanding of the present invention, reference will now be made, by way of example only, to the Figures as shown in the accompanying drawing sheets, wherein:

[0026] FIGS. 1a, 1b illustrate sections through two known temperature control configurations from an inside wall of a container through to a payload;

[0027] FIG. 2a, 2b illustrate first and second perspective views of a phase change panel;

[0028] FIG. 3 shows a view of a container in accordance with the invention prior to placement of the insulating material cover and panels of phase change material with respect to a load;

[0029] FIG. 4 shows a typical non-integrated pallet with a load;

[0030] FIG. 5 shows the temperaturephase characteristic of two types of phase change material;

[0031] FIG. 6 shows an exploded view of a container in accordance with the invention indicating the placement of phase change panels with respect to a load;

[0032] FIGS. 6a and 6b comprise graphs comparing temperature change over time in packaging in accordance with the inventions at with respect to typical external ambient temperatures, as encountered during travel;

[0033] FIGS. 6c and 6d comprise graphs detailing the temperature change over time in packaging in accordance with the inventions at constant specific external ambient temperatures;

[0034] FIGS. 7 shows and example of a modular PCM strip;

[0035] FIGS. 8a-8c show the manufacturing steps in manufacturing PCM modules; and,

[0036] FIGS. 9a-9f show the invention as a form of temp control jacket.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0037] There will now be described, by way of example only, the best mode contemplated by the inventor for carrying out the present invention. In the following description, numerous specific details are set out in order to provide a complete understanding to the present invention. It will be apparent to those skilled in the art, that the present invention may be put into practice with variations of the specific.

[0038] With reference to FIG. 2, an aspect of one embodiment in accordance with the present invention shall be described in a simple to use assembly comprising a cardboard or panel (aka wallet/cassette/envelope/sleeve) 20 in which a number of plastics bags are placed containing phase change materials (PCM) are placed. Conveniently, there are four elements placed therein oralternativelyeight elements placed therein in two layers. Other configurations are possible; simplicity is, nonetheless, of benefit. This embodiment of the invention utilises plastic bags filled with phase change materials, to maintain the internal product temperature between +15 to +25, which temperature is also known as the Control Room Temperature (CRT).

[0039] Such panels are conveniently dimensioned to be placed with a suitably tight fit within a container 30 as shown in FIG. 3 but a typical panel will have dimensions of 45028540 mmbut the temperature control panel need not correspond exactly with the inside dimensions of a load volume; there may even be some overlap along edges. Equally, there may be one or more panels per side of the container, given that large panels can become awkward to handle by personnel, for example. An arrangement of phase change materials as contained within plastics bags, as can conveniently be simply manufactured using standard bag filling techniques, as disclosed in a further contemporaneously filed patent application by present application. The phase change materials can be contained within plastics trays (as shall be discussed below), with the panel being shown in cross-section vis--vis a load and panel 20. This figure can be compared to the cross-sectional views shown in relation to the prior art in FIGS. 1a and 1b. Whilst, the present invention may well have a first and second insulation layers, it can be readily understood, a layer of phase change material has been removed from the container system relative to the prior art, whereby to make the packing of shipping (or storage) containers simpler and, importantly, less liable to incorrect packing, by for example, a reversal of the order of the first and second coolant panels 20, as could very be easily be performed by mistake in the prior art systems. A significant effect is that the effective payload area for a given volume is increased, given that the prior art perception of a requirement of separation of distinct phase control materials is not, in actual fact, required.

[0040] FIG. 3 provides a number of different phase change material panels with the phase change material being selected in a simple instance from one of two different phase change materials, PCM1 & PCM2, having phase change temperatures as indicated (+17 C. and +22 C.). A main advantage of the concept behind the present invention is that two or more temperature control panels can be placed within a container having been temperature conditioned at a single temperature, the types of phase change materials, the respective amounts of the different phase change materials and the conditioning temperature being selected dependent upon the anticipated temperatures, the desired internal temperature and the nature of the filling, taking into account the nature of the packing container and associated insulation surrounding the temperature control panels.

[0041] In a first variation, there can be further provided a layer of material having a high thermal conductivity in contact with the plastic bags containing the phase change material, to enable the creation of a surface having a substantially homogenous temperature within the panel, which material is preferably associated with the face adjacent the payload space. In particular, the thermally conductive layer can conveniently be positioned between the plastics bags of phase change material and the face of the panel that would face the payload area. Materials such as metallized film adhered to a carrier paper or a metallized film applied to a rigid plastics sheet and associated with corrugated board can be conveniently provided. Such a material could also form part of the panel body.

[0042] The present invention enables phase change materials about a payload to absorb heat/release energy to resist cold by enabling a phase change material to react with respect to changes in external temperatures, where the phase change materials are selected to define a selected permissible range of temperatures within a payload area of the container. As will be appreciated, as the container enters a reduced temperature zone, the phase change materials will release energy due, at least in part, to a change in phase of a lower temperature rated phase change material. Equally, as the container enters an elevated temperature zone, the phase change materials will absorb energy due, at least in part, to a change in phase of a higher temperature rated phase change material. That is to say, each phase change material will change state from liquid to solid to release energy or will change state from solid to liquid, to absorb energy. As will be appreciated, in a change of phase state, a material will remain at substantially the same temperature; i.e. the temperature of the material remains stable, as can be seen in the graph shown in FIG. 4. It is important to realise that in a freezing phase, energy is released in an exothermic process; whilst in a melting phase, energy is absorbed by the phase change material in an endothermic reaction.

[0043] With reference to FIGS. 5, there is shown a graphical comparison of the solid/liquid states of two types of phase change material as an example of a temperature control containers having panels in accordance with the present invention using two types of phase change material. This dual PCM system, for example, allows for the two phase change materials to be stored at +20 C. and achieve a composite of solid/liquid segments within respective temperature control container. The overall thermal effectiveness of the use of two panels permits protection of the temperature sensitive goods to be achieved with a single conditioning temperature of, for example +20 C. Specifically, and as has been tested in respect of the present invention, a combination of a +17 C. PCM and a +22 C. PCM, when placed in a container can be simply considered at 20 C. as comprising a first liquid phase change material (i.e. the +17 C. PCM), offering maximum thermal protection against cold thermal stress on the system and a second solid phase change material (i.e. the +22 C. PCM), offering maximum thermal protection against thermal stress on the system. It has been found that the provision of a layer of material having a high thermal conductivity in contact with the phase change materials plastics bags to allow a homogenous temperature to be created on the contact face (lowermost face) of the assemblywhere it would contact the payload space in the temperature controlled package.

[0044] Current design practice in temperature controlled package involves:

i) in the case of the use of a single phase change material, then this phase change materials is conditioned in an ideal state depending on the likely thermal challenge to be presented to the temperature controlled package during shipment. However this is troublesome on two counts, namely that the phase change panels must be warmed or cooled to just above or just below their determined phase change temperature, which can be difficult to achieve in normal industrial warehousing scenarios, as such ideal temperature ranges can be as narrow as (for hot shipping conditions) +15 C. to +19 C. and (for cold shipping conditions) +20 C. to +24 C. and; it is very hard to predict what conditions will be experienced by the temperature controlled package during transit.
ii) When two phase change materials are employed, the distinct phase change materials are contained/packaged/installed as two distinct components. It will be noted that these distinct components need to be selected, labelled, conditioned and placed in a distinct layer these components have to be stored at the correct temperature and must be packed in the correct manner to provide the optimal thermal protection.

[0045] The present invention thus allows for a simple, single temperature preparation of the separate phase change containers/panels at standard Control Room Temperature (CRT) conditions. The design requires little training to facilitate use which will safeguard quality of shipment. Importantly the margin for error is significantly reduced. In use, the temperature of the phase change materials is calculated to enable the temperature to be centred about an ideal temperature depending on the thermal challenge to be presented to the temperature controlled package during shipment. However this is troublesome on two counts:

[0046] The phase change materials that are present in the respective panels filled with two different PCMs that have different Freeze/Thaw temperatures. With reference to the embodiments in FIGS. 5-7c:

[0047] PCM1 has a Freeze/Thaw temperature at around +17 C., that at +20 C. would be in a liquid state and would temperature stabilise at +17 C. as it freezes if the TCP was exposed to temperatures less than +17 C. There is a capability to tailor the amount of phase change material in the cassettes whereby the overall thermal response characteristics can be adjusted depending on the thermal challenge anticipated.

[0048] PCM2 has a Freeze/Thaw temperature at around +22 C., that at +20 C. would be in a solid state and would temperature stabilise at +22 C. as it thaws if the TCP was exposed to temperatures greater than +22 C.

[0049] To enable a simple appraisal of the thermal capability of the present invention, extensive thermal testing has been performed, with reference the results of which show a distinct advantage of the Dual Adjacent PCM system of a system with only one or the other PCM contained within. Specifically, with reference to FIG. 6, which shows a container with external insulating panels outside of the PCM panels, in first and second series of tests under, respectively, summer and winter conditions, the three systems being tested, as follows:

Si) The use of a single type of PCM material only+17 PCMwhich provided poor HOT protection as no phase change occurs since such a phase change material is liquid at +20 C.
Sii) The use of a single type of PCM material only+22 PCMwhich provided good HOT protection as phase change occurs at +22 C.
Siii) The use of two types of phase change materials+17 and +22 PCM materialswhich provided good HOT protection as phase change occurs at +22 C.for the +22 PCM material.
Wi) The use of a single type of PCM material only+17 PCMwhich provided good cold protection as phase change occurs since such a phase change material has a phase transition temperature of +17 C.
Wii) The use of a single type of phase change material only+22 PCMwhich provided poor cold protection as phase change occurs at +22 C.
Wiii) The use of two types of phase change materials+17 and +22 PCM materialswhich provided good cold protection as phase change occurs at +17 C.for the +17 PCM material.

[0050] The results of the first and second tests are shown with reference to FIGS. 6a and 6b and it is clear to see that the system using two phase change material embodiment out performs the systems that only utilise one phase change material type, which is common in the TCP market place today.

[0051] In a further set of tests, a prototype system using the same +17 and +22 PCM materialschanging phases, respectively at +17 C. and +22 C. The system was prepared with all the phase change materials conditioned at +20 C. and then tested at two ambient stresses, namely a constant +30 C. (equivalent to many ambient summer conditions) and a constant +5 C. (equivalent to many ambient winter conditions). The results of these tests are graphically shown in FIGS. 6c and 6d, respectively, where it is shown that: under summer conditions a payload temperature was maintained payload between +15 C. to +25 C. for 38 hrs; and under winter conditions a payload temperature was maintained between +15 C. to +25 C. for 68 hrs. It will be appreciated that the ratio of +17 C. to +22 C. phase change materials can be altered to balance the performance levels achieved against the hot and cold stress test profiles. Equally different types of phase change material could be employed. It is believed that by having the two distinct phase change materials conditioned at the same temperature, there is a beneficial synergistic effect in that a different conditioned temperature of two separate phase change materials do not counteract each other.

[0052] Applicants have also developed a process of manufacturing phase change materials wherein phase change materials, in liquid form, can be placed in trays defined in multi-layer thermo-formed plastics films. Plastics such as Acrylonitrile-butadiene-styrene (ABS) and acrylic can also be used to prove relatively rigid assemblies, which can be of benefit. Pre-set phase change material ratios can be adapted for particular circumstances and are placed in respective trays, the material conveniently being placed whilst in a liquid state under low atmospheric pressure and sealed with a plastics film which is used to seal under the application of heat and/or an adhesive. This plastics film could also be conductive, as discussed above.

[0053] Further types of phase change materials are being continuously developed and presently phase change materials are being developed which have putty-like formable handling characteristics at certain temperatures, whereby to enable particular shapes to be created. Such shapes can be encased in plastics films to provide phase change materials in something analogous to blister pack pockets. Manufacturing methods for producing blister packs are well-developed. The primary component of a blister pack is a cavity or pocket made from a formable web, usually a thermoformed plastic. This usually has a backing of paperboard or a lidding seal of aluminium foil or plastic. Blister packs are useful for protecting products against external factors, such as humidity and contamination for extended periods of time. Opaque blisters also protect light-sensitive products against UV rays. In a further alternative of the present invention blister packs can be produced with a shape arranged such that only a percentage of cavities of a blister pack in a pattern being employed, with apertures present where unfilled blisters are present; by combining with another blister pack arrangement in respect of a second phase change material, a two dimensional array of two phase change materials could be prepared. Equally, not all the blister centres in a pattern need be occupied. A third or further phase change material could be provided in the gaps that have remained unfilled. Given that a range of phase change materials exist, by the use of colour coding, visible, for example through a small aperture in a cassette or wallet enclosure, a make-up of a cassette can be determined and temperature conditioned prior to use in a simple fashion.

[0054] It should also be noted that the presentation of phase change material PCM materials is being continually developed. For example, Microencapsulated phase change material sometimes referred to as microPCMproducts are now becoming commonplace. Microencapsulated phase change material products comprise very small dual-component entities consisting of a core material comprised of a phase change materialand an outer shell or capsule wall. The phase change material substance can conveniently be provided as a waxsuch as a paraffin-wax or a fatty acid ester operable to absorb and release energy in the form of heat in order to maintain a particular temperature. In use, in a warm environment with an increasing temperature, the phase change material would initially absorb the heat (the phase change material melts inside the capsule wall) and store it until the temperature drops from the outside environment; at which time, the heat is released (the phase change material re-solidifying within the capsule wall) releasing energy in the form of heat, which can assist in temperature control. At all times, the capsule wall contains the phase change material, so regardless of whether the actual phase change material is in the liquid or solid state, the capsule itself remains as a solid particle containing the phase change material. The capsule wall can conveniently be provided as an inert, very stable polymer. Such phase change materials can be provide in a manner of slurry, where, for example a capsule size of 1-4 m is employed with 35-45% as solid in an aqueous slurry, a paste, where capsules of a size between 10 and 30 m are present as 70% solids with water or as a dry powder, the micro capsules of 10-30 m being processed such that they can be provided with polyurethane foams and the like. Larger beads or capsules, of the order of 2-5 mmsometimes referred to as macroPCM capsules can also be employed.

[0055] Thus, by the use of such micro/macroPCM particles, used with PU foam, and other binders stable products of two or more phase change materials can be reliably be produced. PU foam may be considered as having too much insulator gas by volume; accordingly, a binder may be employed such that the particles are compressed and retained without too much dead space, which can also affect the rate of change. By the use of organic-based phase change material, the phase change properties are not been observed to lose their efficacy over thousands of cycles.

[0056] With reference to FIGS. 8a-8c, an outline process shall now be described: In FIG. 8a, a base multi-layer film is thermo-formed into trays. Using foam technology, for example, a shape-stable foam is placed into the tray cavitiesper

[0057] FIG. 8b. Phase control materials are then introduced into the stabilising foam, followed by sealing of the cavities by the placement of a thermally conductive web used to seal the cavities closed per FIG. 8c.

[0058] This method of manufacture can provide several benefits to users, including the opportunity to Fine tune packaging performance by adjusting a volume fill of each container unit of phase change material. A specific panel could be provided for a particular user/category of use. This benefit could be realised, for example by having instantly available solutions for a particular user, who may wish to have, for example winter and summer configurations, selected on time of year/weather outlook. This would help ensure fit for purpose package design and cost saving for the customer.

[0059] If the packaging were to be only used in extremely cold conditions, then the volume of PCM1 (+17 C.) could be increased, and the volume of PCM2 reduced. This could be achieved by following methods:

1) Increase the Z dimension of the Shape Stable Foam.
2) Increase either the X or Y dimension of the Shape Stable Foam.
3) Altering the Volume of phase change material into each body, typical percentage liquid saturation to shape stable foam volume are in the order of 65% to 90%, therefore the foam volume could be dosed according to the performance requirement without altering the geometry.

[0060] This embodiment allows for simple, single temperature preparation of the Dual phase change material panels at standard Control Room Temperature (CRT) conditions. The design requires little training to facilitate use which will safeguard quality of shipment.

[0061] By changing the fill ratio between stabilising foam and phase change materials, the thermal capabilities can be tuned to cope with a specific transport/storage requirement. For example, a customer with a travel requirement under very hot conditions could opt to pack the shipper with more Heat Protective phase change material than the Cold Protective phase change material for a given number of phase change panels, thus enabling fine tuning of a shipper's capabilities. This coupled with the use of thermal simulation software could be a very useful and powerful combination enabling the very best fit of a customer's needs to the capabilities of the shipping system.

[0062] FIGS. 9a and 9b show an alternative form of the invention, wherein there is provided four phase change coolant panels, in alternate placement of first and second phase change material. The separate phase change packages could be manufactured in a similar fashion to those described with reference to the embodiments shown in FIGS. 8a-8d, the difference residing in the fact that instead of fouror another multipleof phase change materials being present there is only one phase change material per panel. The four phase change packages, PCM1, PCM2 are enveloped by a plastics bag 91, the bag is subsequently evacuated and heat treated such that the bag adopts the outside shape of the four phase change packages and the product of FIG. 9b is realised; the two edges of 93 & 93 then being fused together to form a fold edge 94, which together with fold edges 94, 94 and 94 provides a cylindrical arrangement for the placement within a packing carton as shown in FIG. 9d, with FIG. 9e showing the phase change package placed within a temperature insulating material, such as, expanded polystyrene, with the plastics material being moulded to fill the gaps between the phase change elements, indicated generally by reference G. The body of the shipper carton is designed to be a close fit with the temperature insulating assembly. Equally, it will be appreciated, that each PCM package contains first and second phase change materials. FIG. 9f shows a six-sided linked PCM panel arrangement 95 prior to fastening into a cylindrical arrangement with base and top covers.

[0063] Indeed, by the use of a configurable system as provided by the present invention, a logistics company could fine tune the exact performance level required for a logistics company to overcome differing thermal challenges, coupled with the use of thermal simulation software whereby to allow logistics companies to make informed, safe and reliable decisions about how best to configure their modular phase change material shippers. For example, by the use of the micro/macro PCM particles, a tuned performance of a particular package can be achieved by the simple expedient of controlling the ratio of PCM1 to PCM2. In tests, it has been found that this solution is appropriate for small express parcel shippers (7- 60 litres in volume) used to distribute small temperature sensitive products such as clinical trial supplies and pharmaceuticals, or for small narrow body aircraft pallets employed in cold chain shipping on regional (narrow body) aircraft. However, the use of single PCM per face is more appropriate for the smaller express parcel shippers (7-20 litres in volume). Given a payload volume, then for an expected transport duration, it will be appreciated that the appropriate PCM panels can be selected, conditioned prior to use and positioned within a four or six adjacent rectangular panel container. The benefits are reduced for larger payloads, but then larger pallet shippers are typically provided with distinct internal passive temperature control systems and so this invention can be seen to provide a useful benefit to the smaller parcel shippers.

[0064] Pharmaceuticals, proteins, biological samples and other temperature sensitive products, including food items, are regularly shipped in containers year round and are subjected to a wide range of temperatures. Though they are shipped in insulated containers and/or climate controlled environments, the temperature stability of the shipping containers can be significantly improved by applying the techniques of the present invention, whereby to provide a simple solution to the maintenance of temperature profiles for the transport and storage of temperature sensitive products.

[0065] The advantages of using phase change materials for temperature controlled packaging are numerous. Phase change materials can easily replace dry ice or gel packs to reduce the size of shipping containers; they can increase the duration of a temperature control period during shipping. Phase change materials are available to cover a wide range of temperatures. A reduction in transportation costs can simply be realised since less space is devoted to cooling systems, when phase change materials are employed. Phase change materials are reusable. Phase change materials assure predictable and stable temperature control and can be effectively used in a passive temperature control system for transport/storage containers.