Relating to insulation

Abstract

A flexible insulation material comprising a flexible porous medium defining a pore volume, and a phase change material (PCM) within the pore volume.

Claims

1. A flexible insulation material comprising a flexible porous medium comprising fibres and defining a pore volume, and a phase change material (PCM) within the pore volume, wherein the phase change material fills in the range of from 40 to 95% of the pore volume, and a remaining part of the pore volume comprises air.

2. The insulation material of claim 1, wherein the flexible insulation material bends under its own weight (to be measurable under ASTM D1388) when the PCM is in a liquid state.

3. The insulation material of claim 1, wherein the insulation material is flexible when the PCM is in a solid state.

4. The insulation material of claim 1, wherein the material is vapour permeable.

5. The insulation material of claim 1, wherein the fibres have a mean fibre diameter in the range of from 1 to 10 μm.

6. The insulation material of claim 1, wherein the porous medium comprises a polyolefin.

7. The insulation material of claim 1, wherein the porous medium comprises a polymeric non-woven material.

8. The insulation material of claim 1, wherein the porous medium comprises a melt-blown.

9. The insulation material of claim 1, wherein the PCM is organic.

10. The insulation material of claim 1, wherein the PCM is hydrophobic.

11. The insulation material of claim 1, wherein the phase change material changes phase at a temperature in the range of from 5 to 30° C.

12. An insulation laminate comprising a layer including a flexible insulation material comprising a melt-blown flexible porous medium comprising fibres having a mean fibre diameter in the range of from 1 to 10 μm and defining a pore volume, and an organic, hydrophobic phase change material (PCM) within the pore volume wherein the phase change material fills in the range of from 40 to 95% of the pore volume, and a remaining part of the pore volume comprises air, said layer being sandwiched between first and second supplementary layers.

13. The insulation laminate of claim 12, wherein the supplementary layers comprise a barrier layer for resisting penetration of the PCM from the flexible insulation material layer out of the insulation laminate.

14. The insulation laminate of claim 13, wherein the barrier layer comprises a monolithic film.

15. The insulation laminate of claim 14, wherein the monolithic film comprises cellulose, ethylene vinyl alcohol, or a combination thereof.

16. The insulation laminate of claim 12, wherein the supplementary layers comprise a reflective layer having an emissivity of less than 0.5.

17. The insulation laminate of claim 12, wherein the supplementary layers comprise a support layer, the support layer comprising a fibrous woven or non-woven material.

18. The insulation laminate of claim 12, comprising a sealed pouch of the insulation material.

19. A cargo cover comprising an insulation laminate comprising a layer including a flexible insulation material comprising a melt-blown flexible porous medium comprising fibres having a mean fibre diameter in the range of from 1 to 10 μm and defining a pore volume, and an organic, hydrophobic phase change material (PCM) within the pore volume wherein the phase change material fills in the range of from 40 to 95% of the pore volume, and a remaining part of the pore volume comprises air, said layer being sandwiched between first and second supplementary layers.

20. The cargo cover of claim 19, comprising one or more pockets for removably receiving said insulation laminate.

21. The cargo cover of claim 19, having a deployed configuration defining a cavity for receiving a pallet of cargo.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

(2) FIG. 1 is a cross-sectional view of an insulation pouch in accordance with an embodiment of the invention; and

(3) FIG. 2 is an illustration of an automated apparatus for manufacturing insulation pouches.

DETAILED DESCRIPTION

Example 1—Solid State Flexibility

(4) The flexibility of a PCM (CrodaTherm™ 21) in the solid state alone and absorbed on fibres was compared.

(5) Two 100 g sheets comprising CrodaTherm™ 21 were prepared. Sheet one was made from a homogeneous sheet of 100% CrodaTherm™ 21. Sheet two was made from 100 g of CrodaTherm™ 21 absorbed in 280 g/m.sup.2 of polypropylene (PP) meltblown fibre having a mean fibre width of typically 2 μm.

(6) The flexibility of the sheets with the CrodaTherm™ 21 in solid form was tested. Sheet one broke and crumbled when it was flexed. Sheet two bent when it was flexed. This shows that PCMs when held within a fibrous layer can remain flexible in a solid state.

Example 2—PCM Holding Capacity of Polyester (PET) Wadding and PP Meltblown

(7) The absorption capacity of two different fibrous polymer materials for a PCM (CrodaTherm™ 21) was investigated, as was the ability of the two materials to hold the PCM when suspended vertically. The properties of the two materials are compared in Table 1 below.

(8) TABLE-US-00001 TABLE 1 Comparison of the properties of PET wadding and PP meltblown PET Wadding PP Meltblown Nominal Weight (g/m.sup.2) 190 280 Fibre Diameter (μm) 17 2 Bulk Density (kg/m.sup.3) 17.27 140 Free Volume (%) 98.75 84.62

(9) An A4 (i.e. 210 mm×297 mm) sample an of approximately 11 mm thick 190 g/m.sup.2 PET wadding and an A4 sample of an approximately 2 mm thick 280 g/m.sup.2 PP meltblown were each exposed to approximately 100 g of CrodaTherm™ 21 PCM and hung vertically from a corner of the sample, with a container placed underneath. After hanging vertically for 5 minutes the samples were re-weighed.

(10) It was found that the PET wadding had lost 65% by weight of the PCM. There was no change in the weight of the meltblown sample.

(11) The amount of PCM able to be absorbed and held within a fibrous layer was therefore found to be dependent, for any given weight/unit area of fibrous material, on the absorbent capacity of the fibrous layer and the total surface area (the external dimensions) of the structure. The greater the total fibre surface area of the absorbent medium the greater the load of PCM it is able to hold.

Example 3—PCM Holding Capacity of PP Spunbond and PP Meltblown

(12) The objective of this study was to assess how two different materials compromised of the same polymer-polypropylene (PP), but with different fibre diameters, absorb PCM (CrodaTherm™ 21) and hold the PCM when suspended vertically. The properties of the two polypropylene materials investigated, PP spunbond and PP meltblown, are compared in Table 2 below.

(13) TABLE-US-00002 TABLE 2 Comparison of the properties of PP spunbond and PP meltblown PP Spunbond PP Meltblown Nominal Weight (g/m.sup.2) 50 40 Fibre Diameter (μm) 22 2 Bulk Density (kg/m.sup.3) 250 100 Free Volume (%) 72.5 89

(14) A4 samples with thickness between 0.2-0.4 mm were taken of a nominal 40 g/m.sup.2 PP meltblown and a nominal 50 g/m.sup.2 PP spunbond. 25 g of CrodaTherm™ 21 PCM was poured on to the top surface of each sample. Each material was weighed after exposure to CrodaTherm™ 21 to see how much had been absorbed. Each sample was then hung vertically from a corner of the sample, with a container placed underneath. After 10 minutes elapsed the samples were re-weighed to assess the amount of CrodaTherm™ 21 remaining in the sample. The results of the study are shown in Table 3 below.

(15) TABLE-US-00003 TABLE 3 Comparison of PCM holding capacity with different fibre diameters (weights measured to the nearest 0.5 g) 50 g PP Spunbond 40 g PP Meltblown Start weight (g) 3.0 3.0 Sample weight after 21.5 28.0 PCM exposure (g) Amount of PCM 18.5 25.0 absorbed (g) % PCM absorbed 74.0 100.0 Sample weight after 12.5 27.0 hanging (g) Weight change after 9.0 1.0 hanging (g) % weight change 42.9 3.6

(16) Adding 25 g of the PCM to the PP spunbond sample completely saturated the sample. By contrast, the finer fibre PP meltblown sample was not 100% saturated when adding 25 g of the PCM, with dry areas of material visible to the naked eye. Despite the higher basis weight of the PP spunbond sample, the finer fibre PP meltblown demonstrated a higher holding capacity of PCM.

Example 4—Insulation Laminate

(17) Two 11 mm thick low emissivity insulation assemblies were compared. Both assemblies contained the same primary insulation material. One assembly contained a secondary insulation layer consisting of approx. 2 mm meltblown PP with approx. 1.6 kg/m.sup.2 CrodaTherm™ 21 PCM absorbed into the material. The other assembly contained no secondary insulation layer.

(18) Identical pallets formed from empty cardboard boxes were covered by each of the assemblies, and each assembly was exposed to the same external ambient climate conditions (direct sunlight; average air temp. 21.8° C.; min. air temp. 16.9° C.; max. air temp. 28.9° C.). The change in temperature between the insulation assembly and a small empty box on top of the pallet was monitored over time. The starting temperatures in the boxes above the loads were 17.2° C. for the pallet covered by the assembly with PCM and 16.9° C. for the pallet covered by the assembly without PCM.

(19) The pallet covered by the assembly without PCM warmed to 25° C. within 56 minutes and hit a maximum temperature of 35.2° C. over the 5 hour exposure. The pallet covered by the assembly comprising PCM took 4 hours 56 minutes to reach 25° C., i.e. 4.3 times longer than the assembly without PCM, and hit a maximum temperature of only 25.3° C.

(20) A further external comparison of primary insulation materials with different emissivities combined with a secondary PCM insulating layer was conducted. Two assemblies were prepared. One assembly had an 11 mm thick primary insulation material with an outer layer emissivity of 0.02-0.05 and a secondary layer of CrodaTherm™ 21 PCM. The other assembly had an 11 mm thick primary insulation material with an outer layer emissivity of 0.16-0.18 and a secondary layer of CrodaTherm™ 21 PCM.

(21) Identical pallets were made up with boxes filled to 20% capacity with 500 mL bottles of water. A small box was placed on the top of each pallet containing a temperature probe. An A4 secondary layer of PCM (100 g CrodaTherm™ 21) was placed over the temperature probe box. The pallets were then covered by the above different emissivity covers and put outside and exposed to the same external ambient climate (direct sunlight; average air temp. 27.4° C.; min. air temp. 23.3° C.; max. air temp. 31.1° C.). The starting temperatures in the boxes above the loads were 19.2° C. for the pallet covered by the assembly having a primary insulation material with an outer layer emissivity of 0.02-0.05, and 19.1° C. for the pallet covered by the assembly having a primary insulation material with an outer layer emissivity of 0.16-0.18.

(22) It was found that the assembly having a primary insulation material with an outer layer emissivity of 0.02-0.05 extended the time taken for the measured temperature of the assembly to warm to 25° C. by 1 hour 17 minutes as compared to the assembly having a primary insulation material with an outer layer emissivity of 0.16-0.18.

(23) Thus, it has been found that the introduction of even a relatively thin secondary layer of PCM to a primary insulation structure demonstrates a significant improvement to thermal protection. Moreover, introducing a lower emissivity (<0.05) outer layer to the primary insulation structure improves thermal protection even further.

Example 5—Insulation Pouch

(24) FIG. 1 shows an insulation pouch 100 according to an embodiment of the invention. In order to avoid PCM leaching out from the PCM adsorbed flexible fibrous layer 110 in its liquid state, the flexible fibrous layer is encapsulated by suitable barrier layers 120, 130 sealed together at both ends 140, 150 to form insulation pouch 100 as shown.

(25) The barrier layers 120, 130 encapsulating the PCM adsorbed flexible fibrous layer 110 may be made of any film resistant to penetration to the chosen PCM. Cellulosic film, polyamide film and EVOH have been found to be resistant to the PCM CrodaTherm™ 21, an oily plant derivative. The barrier layers 120, 130 may be monolithic, co-extruded or laminated films. Such films can be coated with any suitable heat sealable layer such as LDPE, PVDC, PET, PTFE or PUR. Alternatively in order to improve the breathability of pouch 100, an adhesive net may be applied to the barrier layers 120, 130 to provide a method of sealing the perimeter of the insulation pouch 100.

(26) Insulation pouch 100 may be made to any shape or size to enclose its intended load. Consecutive insulation pouches 100 may be joined together to cover large areas or odd shapes. The insulation pouches 100 can be joined by overlapping, butt joining or any suitable known method.

Example 6—Automated Manufacturing of Pouches

(27) FIG. 2 shows an automated apparatus 200 for manufacturing insulation pouches 100. The apparatus 200 comprises a series of three unwind stations 210, 220 and 230. Unwind stations 220 and 230 pay off top and bottom barrier layers 120 and 130 respectively. A series of smaller rollers 225 and 235 assist with delivery of the barrier layers 120, 130.

(28) Unwind station 210 pays off a flexible fibrous layer 160. Assisted by small roller 215, unwind station 210 feeds into a coating system 240 where a defined amount of liquid PCM is applied to the fibrous layer 160 to form PCM adsorbed flexible fibrous layer 110. Coating system 240 may, for example, apply the PCM to the flexible absorbent 160 layer by dipping, spraying or transfer coating.

(29) As the PCM adsorbed flexible fibrous layer 110 exits the coating system 240, it is cut into the required length for a pouch. The length of PCM adsorbed flexible fibrous layer 110 is then deposited onto barrier layer 130, which is delivered to the exit of coating system 240 from unwind station 230 by small roller 235. Barrier layer 120 is simultaneously deposited on top of the length of PCM adsorbed flexible fibrous layer 110, having been delivered to the exit of the coating system 240 from unwind station 220 by small rollers 225.

(30) The three layers are brought together and presented to a sealing unit (not shown). The sealing unit bonds barrier layers 120, 130 together around the perimeter of the PCM adsorbed flexible fibrous layer 110, thus encapsulating the PCM adsorbed flexible fibrous layer 110 and forming insulation pouch 100. Sealing may be by any known method such as heat sealing or ultrasonic welding.

(31) The insulation pouch 100 may be cut at both ends 140, 150 by a cutting machine (not shown) to form an individual insulation pouch 100, or may not be cut to provide a string of joined insulation pouches 100.

(32) Lay flat tubing or centre fold material may alternatively be used to form the barrier layers 120, 130 from a single piece of material, in order to reduce the number of required seals and improve processing efficiency.

Example 7—Cargo Covers

(33) A comparison of the suitability of the insulation laminate of Example 4 and Peli Biothermal Coolgel GP2840 (Comparative Example A) for use in cargo covers is shown in Table 4.

(34) TABLE-US-00004 TABLE 4 Comparison of suitability of insulation materials for use in cargo covers Example 4 Comparative Example A Insulation material CrodaTherm ™ 21/ Peli Biothermal Coolgel melt-blown GP2840 polyproplene Freezing temperature 19° C. 0° C. Refrigeration required? No Yes Freeze/Melt cycle Yes No - Freezing temperature during shipment below ambient conditions

(35) Recently, the performance of cargo covers has been enhanced with the use of traditional phase change mediums such as Peli Biothermal Coolgel GP2840. However, once this product has changed from a solid to a liquid state, the process cannot be reversed without refrigeration. For this reason a large quantity of Peli Biothermal Coolgel GP2840 must be frozen to −18° C. prior to transportation. For this reason Peli Biothermal Coolgel GP2840 is not suitable for integration into a cargo cover.

(36) By absorbing CrodaTherm™ 21 into melt-blow polypropylene fibre wadding, it is possible to integrate the insulation material into the cover and also maintain the cover at a temperature between 15 to 25° C. using just three-quarters of the weight of CrodaTherm™ 21 compared to Peli Biothermal Coolgel GP2840, and without the need for any refrigeration (depending on the ambient temperature).

(37) CrodaTherm™ 21 has freezing and melting temperatures of 19° C. and 21° C. respectively. As a load may experience temperature variations above and below this temperature during transportation, the ability of the insulation material of Example 4 to undergo repeated phase transitions means that it will continue to function through each ambient temperature change across this range. Unlike Peli Biothermal Coolgel GP280, the insulation material of Example 4 does not need to be separated from the pallet and the cargo cover to be re-frozen. Hence it is ideally suited for integration into cargo covers.