A THERMAL CONTROL BOARD AND INSULATING TRANSPORT AND STORAGE CONTAINER THEREOF

Abstract

The present invention relates to the field of the transportation and storage of goods and, in particular, to a box or box-like transport container formed of corrugated board or laminated board that can provide a high degree of thermal insulation. More particularly, the present invention relates to board for the use in such storage containers formed from such board that comprise a box or box-like container, being a hand-held container or a pallet shipper.

Claims

1) A thermally insulating laminated board comprising: a first generally planar sheet of substrate; a second generally planar sheet of substrate, an insulating sheet material operably secured between the first and second sheets; Wherein the insulating material comprises one or more layers; Wherein at least one layer is provided with an array of apertures; and, Wherein at least one sheet is provided with a passive reflectance layer.

2) A laminated board according to claim 1, wherein the one or more layers of insulating sheet material comprise a corrugated sheet material, comprising a first backing layer and a corrugated material upon a surface thereof.

3) A laminated board according to claim 2, wherein only the corrugated material is apertured.

4) A laminated board according to claim 1, wherein the one or more layers of insulating sheet material is an embossed sheet material.

5) A laminated board according to claim 4, wherein the embossed sheet material is mounted with respect to a backing layer.

6) A laminated board according to claim 5, wherein only the embossed material is apertured.

7) A laminated board according to claim 1, wherein the insulating sheet material is a low density foam material.

8) A laminated board according to claim 7, wherein the foam sheet material is mounted with respect to a backing layer.

9) A laminated board according to claim 8, wherein only the foam material is apertured.

10) A laminated board according to any one of claims 1-9, wherein one or more layers of insulating sheet material is placed between a reflective coating provided upon the layers that sandwich the insulation material.

11) A laminated board according to claim 10, wherein a passive reflectance coating is provided upon the inside faces of the layers that sandwich the insulation material.

12) A laminated board according to claim 1, wherein at least one layer of the insulating sheet material is provided with a passive reflectance coating upon one or both of the sides of the insulating sheet material.

13) A laminated board in accordance with any one of claims 1-12, wherein subsequent or successive layers of apertured material are arranged such that the apertures are not identically overlapping.

14) A laminated board in accordance with claim 1, wherein the first and second planar sheets of substrate comprise tubular sheets of substrate, whereby to provide a thermally insulated tube.

15) A laminated board in accordance with claim 14, wherein the tube has a cross-sectional form being one of a circle, ellipse, rectangle, square or other polygon.

16) A laminated board according to any one of claims 1-15, wherein the apertures are defined by a pattern of apertures cut or pressed from an insulating layer of material or by the spacing of strips of insulating material.

17) A laminated board according to claim 16, wherein the apertures are uniformly or randomly spaced apart.

18) A laminated board in accordance with any one of claims 1-17, wherein the apertures comprise one of a circle, ellipse, triangle, rectangle, polyhedron or a series of parallel slots.

19) A laminated board in accordance with any one of claims 1-18, wherein the apertures are defined by the spaces between two sets of diagonally offset overlapping parallel spaced apart strips of corrugate material.

20) A laminated board according to claim 19, wherein the first and second sets of corrugate strips are arranged at a diagonal to the corrugate flute direction and the strips being arranged at a corresponding such that the flutings thereof mesh with respect to each other.

21) A layered insulating board in accordance with any one of claims 1-18, wherein the apertures are not present about a peripheral section of the insulation layers.

22) A layered laminated board in accordance with any one of claims 1-21, wherein the insulating board is fastened by an adhesive.

23) A layered laminated board in accordance with any one of claims 1-22, wherein the insulating board is secured by means of a frame secured about the outside edges of the board.

24) A layered laminated board in accordance with any one of claims 1-23, wherein the insulating board is secured by means of envelope about the outside edges and face of the board.

25) A method of creating a thermally insulating laminated board comprising the steps of: Obtaining first generally planar sheet of substrate; placing an insulating sheet material operably secured between the first and second sheets; placing a second generally planar sheet of substrate; and fastening the sheets together by the use of one or more of adhesive, compression, placement in an enclosure; Wherein the sheets are generally coextensive; Wherein the insulating material comprises one or more layers; Wherein at least one layer is provided with an array of apertures; and, Wherein at least one sheet is provided with a passive reflectance layer.

26) A method according to claim 25, wherein first generally planar sheet is placed upon a mandrel operably mounted for rotation about an axis; the first sheet being arranged about the mandrel to provide a first layer; wherein the insulating sheet is supplied as a continuous web, having a width in correspondence with the width of the first layer, being in correspondence with a desired axial length of the mandrel, whereupon the mandrel is rotated a number of time to provide a number of layers of insulating sheet; and, wherein the second sheet is applied outside the circumference of the mandrel covered by the first sheet and one or more insulating layers.

27) A method according to claim 25, wherein the layers are secured by being placed within an envelope.

28) A method according to claim 25, wherein the layers are secured by being fastened by an adhesive.

29) A method according to claim 25, wherein the layers are laterally secured within an enclosure.

30) A method according to claim 25, wherein the layers of panels are secured by compression channels about their peripheral edges.

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] FIG. 1 illustrates a section through a corrugation process to produce a single-sided corrugate sheet/the first process in the manufacture of double-faced corrugate sheet;

[0027] FIG. 2 illustrates a conceptual aspect of the invention; Table 1 illustrates variations in conductivity at different temperatures; Table 2 shows a graph depicting conductivity versus gap size of an example in accordance with the invention;

[0028] FIGS. 2a, 2b illustrate two alternative embossed cellulose sheet materials;

[0029] FIG. 3 shows a first design of insulating sheet spacer having square apertures, with rounded corners, with the squares being arranged diagonally with;

[0030] FIG. 4 shows a second design of insulating sheet spacer having hexagonal apertures;

[0031] FIG. 5 shows a third design of insulating sheet spacer having square apertures;

[0032] FIG. 6 show a further design of insulating sheet spacer having round apertures as used in fourth and fifth embodiments of the invention;

[0033] FIG. 7 shows a further embodiment wherein the apertures are triangular Table 3 shows a comparison of density of types of corrugated board; Table 4 shows a comparison of thermal conductivity of types of corrugated board;

[0034] FIGS. 8a-8c show the steps in laying down linear strips of corrugated material insulators;

[0035] FIGS. 9a-9c show plan, perspective spaced and perspective views of an exemplary four-layer insulation sample;

[0036] FIG. 10 is a detail view of an aperture show in FIG. 9a;

[0037] FIGS. 11a, 11b are, respectively, expanded perspective and cross-sectional views of the example panel shown in FIG. 9c; and

[0038] FIGS. 12a-12c show, respectively, perspective, plan and edge views of a panel made in accordance with the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0039] 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.

[0040] It is widely appreciated that laminated board material such as corrugated cardboard in the form of double-sided board (and multiple-sided board) can be extremely stiff in the plane of each sheet. Corrugated board is available in many different material grades with varying paper weights and finishes. Fluting is typically produced using waste fibre and is known as waste-based fluting or can be made using semi-chemical fluting (80% hardwood, 20% softwood) Standard finishes include Kraft (brown), white and mottled, LT (recycled paper) and Test (recycled inner liner). White papers can be coated to provide superior substrate for greater print quality. Standard paper thicknesses start at 125 gsm (grams per square metre) and increase to 150 gsm, 200 gsm and 300 gsm. Different flute weights are also available and depend on the strength of material required. Typical paper weights used for fluting are as follows: 90 gsm; 105 gsm (Most Common Flute Standard); 112 gsm; 150 gsm and 175 gsm. Additionally, there are also a number of commonly used flute profiles or sizes, which are as follows: A flute5 mm; B flute3 mm; C flute4 mm; E flute1. 5 mm; F flute1.2 mm. The flute material is usually manufactured from a waste paper i.e., fully recycled material; or what is known as semi-chem fluting (SC). B flute is the most commonly used cardboard used for packaging applications, with approximately 150 flutes per metre. It is also pertinent to point out that with fibres being natural material, the weight will be dependent upon the base cellulose fibre and the degree of any retained water. Whilst it is intended to use commercially available, off-the-shelf, grade of material, given that metal coatings will be applied, the physical characteristics will vary, enabling for example different thicknesses of board to be employed, noting concomitant cost issues.

[0041] The thermal characteristics of cardboard, namely its thermal insulation performance properties will vary with regard to the above referenced differences in grade, material of construction etc. Typically, a measurement of the equivalent conductivity with respect to an air cavity is made as a convenient reference. In practice, the determination of transmission values can be easily performed comparison with similar, known materials, by considering the insulating board material as a uniform layer sandwiched between two reflector layers. The equivalent conductivity of the whole design can therefore be simply estimated, as is known in the art, per Prof. C Saint-Blanquet of the University of Nantes.

[0042] Applicant Company, in an aim to reduce thermal transmission losses associated with a laminated packaging material has conducted numerous experiments with cardboard and similar materials. In the performance of these experiments, measurements have been performed by considering the material being a layer of insulation between two reflective layers (low emissivity surfaces), whereby to calculate the equivalent conductivity relative to an air cavity. The insulating material is considered as a uniform layer sandwiched between two surfaces, which have also been found to perform when the inside surfaces of the two outer layers are provided with a reflective coating. For simplicity, it has been found that the thermal conductivity decreases when the gap between the two outer layers increasesi. e. the thickness of the insulating material increases. In order to confirm these theoretical values, prototypes were made with defined geometries that have been choose arbitrarily.

[0043] Applicant Company, with a desire to reduce thermal transmission losses associated with specific multilayer boards, comprising single-faced corrugated cardboard that has been coiled as is known from GB2585317 in the name of Applicant Company. With reference to FIG. 2, a prototype board sample 20, in accordance with the invention, was made with first and second outer boards, 22, 23 having a number of square apertures (not shown in this side view) in the corrugated material 24, spacing the two board materials was made with 1010 mm apertures spaced from each other by 5 mm whereby a weight reduction of 64% was realized for the insulation layer. These specific dimensions were selected so that thermal convection phenomena associated with the specific board design could be ignored in associated theoretical modelling, although this was later proven to be unnecessary. In practice, however, the board needs to dimensioned so as to fit within a framework suitable for the cold chain product, whether coiledwhen axial end caps need to be configured or made as a rectangular box with six (or more) panels arranged to fit together, with care being taken to ensure that the edge members are fastened and sealed to prevent unwanted heat transfer issues to occur and this can be performed in a number of fashions as known to those skilled in the art. With reference to FIGS. 2a and 2b, the thermal characteristics of an exemplary uniform material with a thermal conductivity of 0.034 W.Math.m.sup.1.Math.K.sup.1, layered between two the reflective layers boards 22, 23 with an emissivity of 0.1, would drop to 0.029 W.Math.m.sup.1.Math.K.sup.1 with the opening described above resulting in a performance gain of 15%. Applicants have determined that measurements performed on single fluted corrugated cardboard showed encouraging results proving the design concept and the analytical solution. This material has been chosen due to its low price and widespread availability. The material conductivity went from 0.044 W.Math.m.sup.1.Math.K.sup.1 to 0.038 W.Math.m.sup.1.Math.K.sup.1. It will be appreciated that other three-dimensional sheet materials such as embossed paper or card can be employed; FIGS. 2a and 2b show exemplary sheets of embossed cellulose sheets. As the skilled man will appreciate, embossed cellulose shares similar strength and spacing attributes with corrugated cellulose materials; if bespoke embossing is provided, then the embossing could be arranged so that even when one sheet is pressed against another, the two embossed sheets do not have a thickness less than the sum of their separate thicknesses, noting that two oppositely directed corrugate boards will mesh one with respect to another whereby the sum thickness in mesh mode is considerably less than the sum of their separate thicknesses. This has the result that an embossed board can be reflective yet not need a backing support, although there would then be a change to the convection characteristics; for example, every other embossed board could be apertured to counter this.

[0044] For clarity, the designs shown per images of FIGS. 3-7 have been ranked with the most desirable design first as of the date of filing and for a particular desired outcome. However, this hierarchy is subject to requirements depending on various constraints such as, but not limited to: feasibility, cost, and final structure's strength. All dimensions are set for their nominal values to increase thermal insulation's performance. These values are ideal and should be adapted depending on manufacturing capability and mechanical properties. The aperture-sheet material density ratio for a sample is the ratio of the area of the support material between the first and second outer surfaces to the corresponding area of said first outer surface (or second outer surface, since they are equal). It could also be expressed as a percentage indicating how much surface area the frame cover. Hence, the apertured sheet surface covering is 1. To achieve the highest thermal insulation, the aperture-sheet material density ratio should be minimized reducing the thermal bridges. The material used as an insulator for the theoretical thermal conductivity value was single faced corrugated cardboard.

[0045] FIG. 3 shows a first design of insulating sheet spacer having square apertures, with rounded corners, with the squares being arranged diagonally with respect to a flute direction as indicated with reference to FIG. 3a, with the sides being defined therein where apertures within the inside start winding portion side edge 31 of the single sided corrugated winding 11. In a coiled product, the flutes of the corrugated material conveniently face inwardly, with a liner being employed when a box has been assembled. Notwithstanding this, it may be more conveniently to have the flutes directed outwardly [0046] Characteristic length: L.sub.c=40 mm [0047] Gap between adjacent apertures: d.sub.gap=7 mm [0048] Distance between aperture centres: d.sub.ip=47 mm [0049] Aperture-sheet material density ratio:

[00001]$\begin{array}{cc}=\frac{d_{\mathrm{ip}}^2-{\mathrm{Lc}}^2}{d_{\mathrm{ip}}^2}& =0.276\end{array}$ [0050] Theoretical conductivity value: .sub.hot=0.033 W.Math.m.sup.1.Math.K.sup.1

[0051] FIG. 4 shows a second design of insulating sheet spacer having 20 mm radius hexagons (20 mm side length) separated from each other by a 7 mm gap. Each row was arranged so the diameter d parallel to the flute direction would fall midway with respect to a gap between two hexagons in adjacent rows, with the distance between two hexagon centres from the same row being 41.6 mm. [0052] Characteristic length: L.sub.c=20 mm [0053] Gap between adjacent apertures: d.sub.gap=7 mm [0054] Distance between aperture centres: d.sub.ip=47 mm [0055] Aperture-sheet material density ratio:

[00002]$\begin{array}{cc}=\frac{{\left(\mathrm{Lc}+\frac{d_{\mathrm{gap}}}{2\sin /3}\right)}^2-L_c^2}{{\left(\mathrm{Lc}+\frac{d_{\mathrm{gap}}}{2\sin /3}\right)}^2}& =0.308\end{array}$

[0056] FIG. 5 shows a third design of insulating sheet spacer having square apertures of 40 mm, 3 mm radius rounded corners, having first and third parallel sides parallel to the flute direction and the other second and fourth sides being perpendicular to the flute direction. [0057] Characteristic length: L.sub.c=40 mm [0058] Gap between adjacent apertures: d.sub.gap=7 mmparallel to flute [0059] Gap between adjacent apertures: d.sub.gap=157 mmperpendicular to flute [0060] Distance between aperture centres: d.sub.ip=47 mm [0061] Aperture-sheet material density:

[00003]$\begin{array}{cc}=\frac{\left(L_c+d_{\mathrm{gap}}\right)\left(L_c+d_{\mathrm{gap}}\right)-L_c^2}{\left(L_c+d_{\mathrm{gap}}\right)\left(L_c+d_{\mathrm{gap}}\right)}& =0.381\end{array}$

[0062] FIG. 6 relates to fourth and fifth designs of insulating sheet spacer each having circular apertures of 20 mm diameter, with a separation of 7 mm. However, the alignment of the circles was arranged such that each row was shifted respectively by 47 and 117 mm respectively.

Fourth Design:

[0063] Characteristic length: L.sub.c=20 mm [0064] Gap between adjacent apertures: d.sub.gap=7 mm [0065] Distance between pattern centres: d.sub.ip=47 mm [0066] Aperture-sheet material density:

[00004]$\begin{array}{cc}=\frac{d_{\mathrm{ip}}^2-{\mathrm{Lc}}^2}{d_{\mathrm{ip}}^2}& =0.431\end{array}$

Fifth Design:

[0067] shift between circlesper fifth design [0068] Characteristic length: L.sub.c=115 mm diameter [0069] Gap between shape d.sub.gap=20 mm [0070] Distance between pattern center d.sub.ip=117 mm [0071] d.sub.ip=135 mm [0072] Void-matter density ratio:

[00005]$\begin{array}{cc}=\frac{d_{\mathrm{ip}}^2-{\mathrm{Lc}}^2}{d_{\mathrm{ip}}^2}& =0.342\end{array}$

[0073] FIG. 7 relates to a sixth design of insulating sheet spacer comprising equilateral triangles with one side parallel to the flute and the others by 60 to the flute, the base length being 40 mm and the spacing between triangles being spaced by a 7 mm gap between their respective sides. [0074] Characteristic length: L.sub.c=40 mm [0075] Gap between adjacent apertures: d.sub.gap=7 mm perpendicular to flute [0076] Distance between pattern centres: d.sub.ip=28.08 mm

[00006]$\mathrm{Aperture}\mathrm{sheet}$$\mathrm{material}\mathrm{density}\mathrm{ratio}:\begin{array}{cc}=\frac{\left(\frac{L_c}{2}+\frac{23}{3}{d}_{\mathrm{gap}}\right)\left(\frac{L_c}{2}+\frac{23}{3}{d}_{\mathrm{gap}}\right)-\frac{3}{4}{L}_c^2}{\left(\frac{L_c}{2}+\frac{23}{3}{d}_{\mathrm{gap}}\right)\left(\frac{L_c}{2}+\frac{23}{3}{d}_{\mathrm{gap}}\right)}& =0.985\end{array}$

[0077] Tables 3 and 4 comprise tables relating, respectively, to density and thermal conductivity of a number of exemplary models, provided with six layers of insulating material. From a brief review the skilled man can readily determine that the density of a corrugated board with apertures yet supporting a reflective surface is lower with respect to a non-apertured corrugated board without any reflective coating.

[0078] FIGS. 8a-8c relate to a further embodiment; rather than cutting apertures in corrugated paper or embossed cellulose sheet, strips of corrugated paper 101 are provided, where the strips are cut at 45 to the flute direction and are mounted with respect to cardboard/paperboard 102, with the strips 101 of corrugate paper each arranged at sheets at 45 to an axis of the cardboard/paperboard. It is to be noted that FIG. 8b is viewed from rear and for the purposes of explanation, the cardboard/paperboard 104 is translucenti. e. the cardboard/paperboard of 8a and 8b is the same (only three and four strips of corrugate 101, 103 are shown for clarity), with the corrugate strips lying in the same directionwhich makes manufacture relatively simple in that there is no interference arising from two types of board with strips running diagonally with respect to each other. With reference to FIG. 8c, it can be seen that when presented together, the corrugate paper strips of the respective first and second boards mesh, as indicated by reference numeral 105, mutually adding to the strength of the resultant board 106, whilst still maintaining very good insulation qualities.

[0079] FIG. 9a show a composite insulation member 110 suitable for positioning between first and second cover sheets (not shown), with four insulation sheets as indicated in FIG. 9b, which shows the separate insulation sheets 111a-111d in a spaced apart configuration. Referring to FIGS. 9a, 9b & 10, FIG. 10 is an expanded view of circled section 113 indicated in FIG. 9a. Each sheet comprises a number of generally rectangular apertures with rounded edges as indicated by reference numeral 112; reference numeral 114 indicates a central portion surrounded by four apertures, the dimensions of the rectangle are indicated as 115x and 115y, noting that they are equal for substantially square apertures. Reference numeral 114-1 indicates the central region of a second insulation sheet 111b. The offset is determined to increase the distance of the thermal path length from an inside face of a first cover sheet to an inside face of a second cover sheet, the greater the thermal path, the greater the insulation is provided, noting that the apertures also considerably reduce the conductivity of the insulation sheet member, noting that the thermal conductivity of air will be less than, such insulator, being cellulose fibre such as wood fibre, plastics insulator, air laid tissue and the like.

[0080] FIG. 9c shows the panel in perspective view with a circled feature 116, being a corner section. FIG. 11a shows an expanded view of circled feature 116. Features 114 and 114 in respect of this drawing exemplifies the offset 114-0 between successive layers of insulation material 111a-111d. It will be appreciated that variations in this offset distance 114-0 can be utilised to minimise thermal transmission, dependent upon the number of layers of insulation material the thermal. With reference to FIG. 11b, a section through a sample board shows each layer comprising a single face b-flute single faced corrugate papercorresponding to 3 mm in height glued to a metallized board layer having a thickness typically being 0.04 mm, but such paper can be typically in the range of 0.1-0.01 mm, as discussed above. The skilled man will realize that different flute thicknesses can be employed, together with differences in standard thicknesses, but it will be appreciated that in one aspect, the invention seeks to use the least material possible, to reduce, inter alia, the heat capacity of the insulation panel.

[0081] FIGS. 12a show a perspective view of an exemplary insulation panel 120 made in accordance with the invention comprising 25-layers of insulation of B-flute corrugate boardgiving rise to a 75 mm panel thickness. The edges 121 are secured for this example with compressed fibre board/paper board shaped as a U-section member. This insulation does not include any cover boards for protection. The aperture pattern is shown in FIG. 12b; FIG. 12c shows a corner section. It will be appreciated that the apertured sections are not present about the edge in the sample section.

[0082] The example insulation board shown with reference to FIG. 12 comprises a cardboard-based panel, where, for example a backing sheet of paper or cardboard is provided, conveniently also being provided with a low emissivity coating such as a thin film of metal. Thermal evaporation is a popular physical vapor deposition technique because of its simplicity: a metal in a high-vacuum environment is heated to its evaporation point by joule heating, for example by being placed in a resistive boat into which the metal is placed. Vaporized molecules then travel from the resistive boat or other source to the substrate where they nucleate together, forming a thin film coating. Whilst it is appreciated that a wide variety of materials can be deposited using this technique such as aluminium, silver, nickel, chrome, magnesium, among many others, aluminium is the preferred material because of its availability and cost and can be deposited in amounts which do not significantly add to the weight of a substrate, conveniently being paper or card, noting that the coating will affect the stiffness to an extent. In tests it has been found that a thickness of 5 nm has been found to give good results, but equally good results can be provided by coatings of 3-10 nm in thickness.

[0083] The cardboard fluting could be replaced by other sheet materials such as embossed paper or card is not the only way to described above is not so limited; Polyisocyanurate, also referred to as PIR, polyiso, or ISO, is a thermoset plastic typically produced as a foam and used as rigid thermal insulation, which limits applications where curved board is required, but the benefit of rigidity can assist in the production of packaging where a greater degree of stiffness is preferred. Closed-cell nitrile rubber foam could also be employed where flexibility is desired, as well as EPS, which is widely employed in thermal insulating installations. Notwithstanding the use of plastics in packaging, international regulations increasingly require insulation materials to be recyclable. Accordingly, development of the present invention has been substantially based on the use of natural cellulose sources such as wood (including bamboo).

[0084] Applicant Company has determined that the backing sheet of the presently favoured B-flute material is preferably provided. In one aspect of the invention, the first and second cover elements are provided with reflective surfacesconveniently on the inside faces thereof for durability, one or more of the insulating sheets of the central insulation composite can also be provided with the reflective coating. Whilst this can be considered as being contrary to an ability to be recycled, since the metallization techniques of vacuum deposition actually deposit very small amounts aluminium, in the region of 0.05 gsm, it is generally held that the aluminium coating is so thin that it doesn't impede the recycling process when, for example, following the INGEDA froth flotation process, being a technique widely employed in the waste paper recycling industry to, inter alia, remove inks and other contaminants by selectively separating of hydrophobic materials from hydrophilic. Accordingly, this makes it a more ecological preferred option compared with other materials that give similar reflective abilitieslike foils or plastic filmsthat can't be recycled conveniently or economically.

[0085] In a preferred embodiment, where there are several layers of insulating material, and referring to FIG. 13a, there is shown a four-layer example of a multi-layered insulation system, comprising layer L13a-L13d, wherein there are three layers, layer L13d being the same as layer L13a, with layers L13b and layer L13c having their apertures 131 being spaced in a horizontal direction by similar amounts to layers L13a and L13b, respectively. FIG. 13e show these layers, once superimposed upon each other as will typically be arranged within an insulation panel in accordance with the present invention. FIG. 14 shows how these layers appear from a cross-sectional point of view, where an offset, between successive layers is easily determined, noting that this is shown from a point of view to simply indicate that the thermal distance from an initial lower face to a subsequent upper face for the transfer of heat from a first outer planar face of insulating material to second outer planar face is greater than the actual, normal (right angle to planar surfaces) distance. It will be appreciated that only a small number of apertures 113a-d are indicated in this figure, for simplicity, as opposed to likely number of, the apertureswith reference to the tables 3 and 4 where density and thermal conductivity indicate the benefits of having a greater aperture in a corrugate/foam/air-laid substrate with board; moreover it is to be understood, the benefits of the present invention increase with greater numbers of insulation layers, for example with 6-40 layers, noting that the example of FIG. 12 has twenty-five insulation layers. This is because it is intended to simply indicate the change in thermal path length. It will be appreciated that such transverse adjustments in spacing are optional but can act with other characteristics to improve the thermal characteristics of the insulation layers.

[0086] FIG. 14 shows a four-layer arrangement of layers, in cross-sectional view, corresponding to, for example, FIGS. 13 a-d. In addition to the first and second outer layers 114a, 114b typically of a thin, low thermal conductivity plastics material, yet sufficiently rigid and durable, to maintain integrity, such as polypropylene of 1-3 mm, the edges of the panel will need to be sealed to a degree. In the example of FIG. 12, the edges have been sealed with a u channel section; in the alternative other types of maintaining integrity of the panel can be envisaged. For example, a water-soluble starch based foam could be used to maintain the layers in position. In another alternative, especially where the insulation panel is to be employed in a secure position and would be, for example, be protected by external and interior walls of a container, the first and second outer panels could comprise of the same type of panel as the insulating layers, ideally with a backing panel of the outer two panels facing outwardly. Such panels could be sheathed in a vacuum arrangement with the use of a plastics sheath or bag, or paper-based vacuum bag, with the vacuum enabling the layers to be held together, without starch glue or with a minimal amount thereof.

[0087] Applicant Company has employed natural adhesives such as starch-based glues to attach the apertured sheets. Starch is a natural polymer and is widely available, generally at relatively low and stable prices. It consists of glucose units chemically bound together so as to form a non-reducing polyhydroxy-material. By reason of the many hydroxyl groups, starch has a high affinity for polar substances such as water or cellulose. Starch can be reduced to low molecular weight sugars by enzymes called amylases, or by acid hydrolysis. Notwithstanding this, other glues or forms of retaining the panels and insulation layers in place may be more appropriate.

[0088] In a further embodiment, the present invention permits an alternate, equally simple method of fabrication of a tubular low thermal conductivity container, with reference to FIG. 15. In this method, a first inside surface board is provided over a mandrel former 151, then, for example a layer of continuous insulation sheet element 153 is attached to the first inside board 152 by starch adhesive or equivalent, whereby once the adhesive is set, then the insulation layer 153 can be wound or coiled about the inside board mounted on the former 151, rotating about an axial support 154. The insulation sheet of width W is fed from a bobbin 155. This system of application can readily for a tubular element; it will be appreciated that this will enable winding of several layers easily, but tension of the sheet, together with relative rotations of the mandrel and bobbin; as the mandrel rotates, the diameter increases and therefore needs to reduce its rate of rotation relative to the bobbin 155. A benefit of this method of application is that the apertures will overlap to a degree, as opposed to being in direct alignment, whereby the thermal path length increases, due to the wound mandrel increasing in diameter. Once the number of desired layers of insulation have bene wound, the edges are secured using suitable starch glue or securement with plastics sheeting, or sheathing, together with the provision of an outer protective sheath or outer protective face member.

[0089] Pharmaceuticals, proteins, biological samples and other temperature sensitive products, including food items, are regularly shipped in containers throughout the year 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 employing the panel structures 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.