WO1999004966A1

WO1999004966A1 - Insulation panels with internal radiant barrier

Info

Publication number: WO1999004966A1
Application number: PCT/US1998/015090
Authority: WO
Inventors: Michael B. Kerschner
Original assignee: Quantum International Incorporated
Priority date: 1997-07-22
Filing date: 1998-07-21
Publication date: 1999-02-04
Also published as: AU8504698A

Abstract

The invention concerns imbedded high thermal performance insulating panels (10) that utilizes sandwiches radiant barriers. The panel (10) is constructed from two or more courses (12, 14, 16) of open cells, defined by cell walls (18) having low conductivity, in between which is disposed a thin radiant barrier. Preferably, a pair of outer skins (40) are bonded to the exposed open cells to provide for a finished product. By layering the courses in vertical non-registry, i.e., misalignment, thermal conductive bridging is further reduced. By using open cell material, thermal convection is reduced. And by incorporating an internal, radiant barrier septum layer (30), thermal radiation is significantly reduced. The resulting product, which may comprise more than two courses of open cells, provides exceptional resistance to heat transference from one side of the panel (10) to the other. Further, a system for mounting the panels (10) is disclosed using barbed fasteners (50). Also disclosed are methods for creating the panels (10).

Description

INSULATION PANELS WITH INTERNAL RADIANT BARRIER

Field of the Invention:

The present invention relates to Multi-Layer Reflective Insulation (MLRI) and more particularly to MLRI panels incorporating an intermediate, radiant barrier septum.

Background of the Invention:

There exist only three known modes of heat transfer: conductive, convective, and radiant. Conductive heat transfer occurs when energy is transmitted by a medium, usually solid in nature, which does not involve the movement of the medium fluid in nature; convective heat transfer occurs when energy is transmitted by a medium that is in motion; and radiant heat transfer occurs when energy is transmitted by waves or particles through a space or vacuum. Conventional insulation used in structures is particularly suited for resisting conductive heat transfer by absorbing heat and eventually re-emitting that absorbed heat. Such insulation also reduces convective heat transfer because it generally creates small air pockets loosely defined by the loft of insulative material, thereby interfering with the ability of air trapped within the pockets to freely move, a precondition to heat transfer via the convective mode. The critical factor in such insulation is the use of non-moving air an insulator (non-moving air is a poor medium for conductive heat transfer). What is noticeably absent in conventional mass fiber or rigid forms of insulation is a true ability to block significant radiant energy/heat transfer. The primary mode of heat transfer in exterior envelope structures is radiant.

As much as 93% of summer interior heat gain and up to 75% of winter interior heat loss can be via radiant heat transfer, principally in the infrared wavelengths. The only way that a structure can significantly reduce radiant heat gain or loss is to incorporate one or more low emissivity barriers into or around the structures. Yet, design professionals in the construction and manufacturing industry continue to place a majority of emphasis on conductive and convective heat transfer modes, in part because radiant barriers and reflective insulations are not accurately measured by the traditional FTC mandated "R" value protocol.

Some manufacturers of conventional mass fiber insulation have incorporated a low emissivity backing to their insulation batts and semi-rigid insulations. These "foil faced" products are desirable in their ability to resist moisture; however, they lack correctly placed adjacent air spaces to create adequate reflectance properties. What is needed are consistent, reflective parallel planes containing segregated air spaces that will force conductive heat to resume its original form of transfer, namely radiant.

SUMMARY OF THE INVENTION

The present invention is intended to provide an insulative barrier having superior emissivity properties in an inexpensive form using readily available construction materials. The insulating panel comprises a first course of open cells defined by a plurality of cell walls and a second course of open cells defined by a plurality of cell walls between which is disposed a radiant barrier septum. The cell walls may be constructed from any suitable material having low conductive properties such as cellulose, polymers, and aramid compositions. A preferred embodiment uses open-ended honeycomb-like cell formations constructed from cellulose. Alternatively, the cell walls can be constructed using polymers such as polycarbonate or polyvinyl materials, especially in high moisture or water environments. Additionally, Nomex^® and aramid fiber materials may be used where undesired combustion is to be avoided. Moreover, substitute geometric configurations may be employed and included using a corrugated pattern wherein the open ends face the outer surfaces of the panel.

The septum material acts as the primary internal barrier to radiant heat transfer. The septum material can be any low emissivity sheet material and is preferably constructed from a three part laminate comprising a polymer sheet substrate to which is bonded on either side a low emissivity metal to provide desirable radiant barrier properties in both directions. In a preferred embodiment, industrial grade aluminum having a purity of about 99% is vapor impregnated onto a Mylar^® or polyethylene sheet substrate to yield a septum having a thickness ranging from 0.0001 to 0.0005 of an inch. Depending upon the applications, it may be desirable to incorporate a scrim weaving to strengthen the septum either for manufacturing purposes or for use-based reasons.

The ultimate choice of septum materials is controlled by the desire to provide an effective radiant barrier. Thus, a thin foil of material is considered an appropriate substitute for the noted laminate. The material should have emissive properties similar to that provided by aluminum and may comprise, for example, alloys of aluminum, gold, silver, platinum or other metals. It is desirable that the septum chosen have emissivities in the range of 5% and less, with emissivities lower than 3% preferred.

Lastly, the outer skin of the panels may be omitted, or constructed from any suitable material capable of being formed into sheet material. In applications wherein an outer skin is not needed, the importance of the function of the septum becomes readily apparent. Such applications may include items such as interior cores for various door types. Imbedded placement within other composite structures, ice cooler walls, hot tub covers and structural panels.

Depending upon the anticipated applications for the panels, it may be desirable to use panels having outer skins. In such instances, the skin material can range from flexible to rigid. In one embodiment, typical cellulose-type kraft paper is used. In most applications, the basis weight of the skin materials should be between 10 and 100 pounds per cubic foot, and preferably between 15 and 50 pounds per cubic foot. In other applications, paneling, drywall, or wallpaper types of finishes may be used, especially when retro-fitting building structures. If structural applications are considered, then skin materials such as rigid plywood or structural siding may be employed. These skin materials are highly desirable in applications wherein structural insulated panels (SIP) are required. By the same token, if the panels of the present invention are to be used in exterior insulated finish systems (EIFS), then suitable netting or mesh skin materials can be used. In addition, if the panel is to be exposed to moisture, and especially to lime, a waterproof outer skin should be incorporated into the panel to reduce exposure of the septum to these compounds. The foregoing discussion concerning a two course embodiment also applies to single course embodiments and embodiments wherein three or more courses are employed. With respect to single course embodiments, the septum material or a simple metalized coating may be disposed on one side of the single course of open cells, or on both sides. Moreover, the septum material may be adhered to an outer skin whereafter the combination may be adhered, either with the septum adjacent to the cells or separated from the cells by the skin, to the cell walls. A three or more course embodiment utilizes the teachings with respect to the two course embodiment, namely the introduction of a septum layer in between each course of open cells. The choice of a single or multiple course embodiment is chiefly driven by the level of convective/conductive heat and/or acoustic insulation desired since each septum layer will preferably reduce radiant heat transmission by about 95%.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a cut-away perspective view of a three course, two septum panel embodiment of the invention wherein each cell course is vertically offset and the septums have very low emissivity values;

Fig. 2 is a plan view of a sinusoidal cell pattern wherein each sinusoidal cell wall is laterally offset by 180° from adjacent cell walls;

FIG. 3 is a cut-away perspective view of a single course panel embodiment of the invention;

Fig. 4 is a side elevation of a barbed fastener used to secure a panel to a substrate; and Fig. 5 is a side elevation of the barbed fastener in Fig. 4 shown bonded to a substrate and engaged with a panel section.

DETAILED DESCRIPTION OF THE INVENTION

Referring then to the several figures wherein like numerals indicate like parts and particularly to Fig. 1 , a cut-away perspective view of a three course, two septum embodiment of the invention is shown. In the present embodiment, panel 10 is shown to consist of a first course 12, a second course 14, and a third course 16 of open cell material having cell walls 18 defining the peripheral surface of each cell 20. Septums 30 are shown disposed between courses 12 and 14, and 14 and 16. The type of open cell 20 illustrated is generally honeycomb-type wherein walls 18 are constructed from cellulose having a basis weight of preferably within 5 to 40 pounds per cubic foot. An alternative to using a honeycomb cell structure is illustrated in Fig. 2 wherein a pair of sinusoidal curves mated in an inverted or 180° offset relationship define each cell 20. Moreover, nearly any type of geometric polygon or circular cylinder may be employed and still achieve desired functionality.

As was set forth previously above and repeated here for convenience, the selection of cell wall material is largely a design choice taking into account required compressive, axial, rack and sheer strength requirements; however, material selection should be limited to those having low thermal conductance properties, low manufacturing costs, and good adhesion characteristics. Thus, thermal conducting materials such as metal should be avoided. Preferably, cellulose, polymers, and aramid compositions are used to form cell walls 18. A preferred embodiment uses open-ended honeycomb cells constructed from cellulose. Alternative construction materials include polymers such as polycarbonate or polyvinyl compositions, which are especially appropriate in high moisture or fluid water environments. Additionally, Nomex^® and aramid fiber materials may be used where undesired combustion is to be avoided. Moreover, substitutes for a honeycomb construction may be employed such as the use of corrugated materials selected from the above referenced materials as illustrated in Fig. 2, or foamed polymeric materials.

Returning to Fig. 1 , each course 12, 14, and 16 is preferably misaligned or staggered relative to any adjacent course. This misalignment or course offset reduces thermal conductive bridging between cell walls 18 of each course 12, 14, and 16 by making the cell wall contact significantly less contiguous. In the embodiment shown, the intentional misalignment reduces the potential for thermal conductive bridging to less than 8% of the total panel surface area when panel 10 is exposed to a heat differential between outer skins 40a and 40b. In other words, because of cell wall misalignment, greater than 92% of the panel surface area is resourcefully designed non-collapsible airspace wherein the mode of heat flux is predominantly non-conductive heat transfer. Because each cell 20 creates a small pocket of trapped air in conjunction with septum 30 and thus reduces convective heat transfer, and because the courses of cells are intentionally offset to reduce conductive heat transfer, the remaining mode of heat transference is essentially radiant. To take advantage of this forced mode of heat transfer, septums 30 are chosen to be highly reflective, i.e., possessing very low emissive properties. In selecting septum materials of this nature, radiant heat transfer is significantly reduced at each septum boundary, leaving only reduced conductive transfer. As illustrated, each septum 30 consists of three layers of material, namely, polymer sheet substrate 32 to which is bonded on both sides aluminum coating 34 and 36 to provide desirable radiant barrier properties in both directions. In the embodiment shown, industrial grade aluminum having a purity of about 99% is vapor impregnated onto a Mylar^® or polyethylene sheet substrate to yield a septum having a thickness ranging from 0.0001 to 0.0005 of an inch.

Using a septum as described above, approximately 97% of radiant energy presented to a septum surface is reflected away from the septum. Taken in combination with the significant reduction in conductive heat transference, it can be seen that the instant invention has a very high level of insulation (reduction in heat flux).

Further reductions in heat transfer can be achieved when outer skins 40a and 40b possess low emissive properties. As illustrated in Fig. 1 , each skin 40 has an aluminum coating or layer 42 and 46 on substrate 44 which itself acts as a thermal break. Again, by providing for dual layers, heat transfer is limited both on the external surface as well as the internal surface of each skin 40.

Depending upon the applications, it may be desirable to incorporate a scrim weaving to strengthen the septum either for manufacturing purposes or for use- based reasons. Similarly, a scrim may be useful when constructing outer skins 40. From the foregoing, it should be clear that a single course embodiment, such as is shown in Fig. 3, is also within the scope of the invention. As with the multiple course embodiment of Fig. 1 , for example, a plurality of cells 20 are defined by cell walls 18. However, the functionality of septum 30 is incorporated into outer skins 40a and 40b. Similar to the metalization treatment of septum 30, outer skins 40 are constructed to have low emissivity properties. This may be accomplished by incorporating a metal component within outer skin 40, or may be accomplished by bonding a septum sheet directly to the outer skin. The later is more desirable when retro-fitting an existing and desirable outer skin such as when a structural member such as plywood or OSB is used as the outer skin. Naturally, such treatment of the outer skin may be made to only the cell facing side (the interior side) or the exterior side, or both depending upon design considerations.

In the present embodiments, all cells, septums, and skins are preferably bonded with an adhesive which includes admixtures composed of polyvinyl acetate material with cross-linking agents. Other types of adhesive may yield desirable results as well and may be even more desirable when constructing more exotic panel configurations.

In applications wherein it is desirable to install panel 10 to a planar backing substrate, barbed fasteners 50, such as illustrated in Fig. 4, are preferred. Barbed fasteners 50, which are available from Quantum International (Puyallup, WA), are ideally constructed from a resilient material such as nylon or any poor conducting material. The choice of this type of material permits barbs 52 to flex towards shaft 54 and return after withdrawal of a compressive force.

To use fastener 50, base 56 is securely fastened or bonded to the substrate using an adhesive such as Eco-Hanger Grip Adhesive 22-15 (Mon-Eco Industries, Inc., East Brunswick, NJ) whereafter panel 10 is impaled upon barbed portion 58 and held captive therewith as is best shown in Fig. 5. Naturally, panel 10 can be adhered directly to a substrate or fastened from the exposed side by conventional means such as screws, nails, or the like.

Because of the inherent versatility of using panels for insulation, it is contemplated that the invention will find use in industries and applications such as the following: Construction Thermal Transportation Thermal Manufacturing

1. Exterior Envelope 1. Refrigeration Trailer 1. Hot Tub/Spa

Insulation Units Covers Walls a. sheathing materials 2. Refrigeration or 2. Factory Work Area b. imbedded in Cryogenic Separation or concrete or earth Vehicles/Vessels Shields c. refrigeration storage 3. Container Shipping 3. EMF Reduction at heated storage Industry - Thin Wall Work Areas d. roofing Insulation underlayment e. insulated suspended ceilings f. insulated ducting material g- road bed equalization insulation

2. Fire Resistive Construction a. elevator shafts b. multi-unit party walls

Claims

What is claimed:

1. A multi-layer insulation panel with an internal radiant barrier comprising: a first course of open cells defined by a plurality of cell walls; a second course of open cells defined by a plurality of cell walls superposed over the first course of open cells; and a septum layer of sheet material disposed intermediate to the first course of open cells and the second course of open cells wherein the septum layer of sheet material has low emissivity properties in at least one direction not parallel to the septum layer surface.

2. The panel of claim 1 wherein the septum layer has low emissivity properties in at least two directions not parallel to the septum surface layer.

3. The panel of claim 1 wherein the first course cell walls are not in vertical registry with the second course cell walls.

4. The panel of claim 1 wherein each of the first course cells does not have the same general internal volume as each of the second course cells.

5. The panel of claim 1 wherein each of the first course cells have the same general internal volume as each of the second course cells.

6. The panel of claim 1 wherein the cell walls are constructed from a non- metallic material having a low thermal conductance.

7. The panel of claim 1 wherein the septum layer comprises a metal foil.

8. The panel of claim 7 wherein the septum layer further comprises a poor thermal ducting substrate to which the metal foil is bonded.

9. The panel of claim 1 wherein the septum layer comprises a laminate sheet substrate having a first side including a metalized layer and a second side including a metalized layer.

10. The panel of claim 1 further comprising at least one outer skin bonded to the first course of cells, thereby enclosing at least some of the first course of cells.

11. The panel of claim 10 wherein the at least one outer skin has low emissivity properties in at least one direction not parallel to the at least one skin surface.

12. The panel of claim 11 wherein the at least one outer skin comprises a metallic layer.

13. The panel of claim 11 wherein the at least one outer skin is substantially parallel to the septum layer.

14. A multi-layer insulation panel with an internal radiant barrier comprising: a first course of open cells defined by a plurality of cell walls wherein the cell walls are formed from a low thermal conductance material; a second course of open cells defined by a plurality of cell walls superposed over the first course of open cells so as not to be in vertical registry therewith, wherein the cell walls are formed from a low thermal conductance material; and a septum layer of sheet material disposed intermediate to the first course of open cells and the second course of open cells wherein the septum layer of sheet material has low emissivity properties in at least one direction not parallel to the septum layer surface.

15. The panel of claim 14 further comprising a first outer skin bonded to at least a portion of the first course cell walls and a second outer skin bonded to at least a portion of the second course cell walls.

16. The panel of claim 15 wherein the first outer skin and the second outer skin comprise a low emissivity layer.

17. The panel of claim 14 wherein the septum layer has an emissivity of less than 5% and a sectional thickness of substantially between 0.0001 and 0.0005 of an inch.

18. A system for establishing panel insulation on a substrate comprising: the panel of claim 15; and a barbed fastener having a base portion and an extending barbed portion wherein the base portion is adaptable to secure to the substrate and the extending barbed portion is insertable into the panel.

19. A method for constructing a multi-layer insulation panel comprising the steps of: a) creating a first course of open cells defined by a plurality of cell walls wherein the cell walls have low conductivity; b) creating a second course of open cells defined by a plurality of cell walls wherein the cell walls have low conductivity; c) creating a septum layer of sheet material having a first side and a second side, and having low emissivity properties; d) bonding the first side of the septum layer to at least a portion of the first course cell walls; and e) bonding the second side of the septum layer to at least a portion of the second course cell walls.

20. The method of claim 19 wherein the first course cells do not have the same internal volume as the second course cells.

21. The method of claim 19 wherein in step e), the second course cell walls are vertically offset from the first course cell walls.

22. The method of claim 19 further comprising the steps of: f) creating an outer skin; and g) bonding the outer skin to at least a portion of the first course cells.

23. The method of claim 22 further comprising the steps of: h) creating a second outer skin; and i) bonding the second outer skin to at least a portion of the second course cells.

24. A single layer insulation panel comprising: a course of open cells defined by a plurality of cell walls wherein the cell walls are formed from low thermal conductance material; and at least one outer skin having an interior side and an exterior side wherein at least a portion of the interior side is bonded to at least a portion of the cell walls defining the plurality of open cells, and wherein the outer skin has low emissivity properties.

25. The panel of claim 24 wherein the interior side of the at least one outer skin has a layer of low emissivity material present thereon.

26. The panel of claim 24 wherein the exterior side of the at least one outer skin has a layer of low emissivity material present thereon.

27. The panel of claim 25 wherein the interior side of the at least one outer skin has a layer of low emissivity material present thereon.