High resistance panels (HRP)

Abstract

A thermal insulation panel is consist of an impermeable barrier and backing, a surface of low emissivity, an adhesive, a mixture of phononic cocrystals at both sides, and a support material in a honeycomb structure in between two sides. The panel reduces heat transfer and has an overall thermal conductivity in order of 10.sup.3 w/(m.Math.K), and a density of 20-100 kg/m.sup.3. The panel can be cut to any sizes to meet requirements for installation, and can be stacked or piled up to meet the requirements of thickness and thermal resistance in application.

Claims

1. A high resistance panel for thermal insulation consisting of a support material having a first side and a second side opposite to the first side, wherein the support material is a honeycomb structure, and the cells of the honeycomb structure extend between the first side and the second side, substantially perpendicular to the first side and the second side; first phononic cocrystals located at the first side and second phononic cocrystals located at the second side; a first impermeable barrier and backing at the first side and a second impermeable barrier and backing at the second side, wherein each of the first impermeable barrier and backing and the second impermeable barrier and backing has a surface of low emissivity of less than 0.03; a first adhesive mixed with at least a portion of the first phononic cocrystals at the first side, which bonds the first impermeable barrier and backing to the first side, and a second adhesive mixed with at least a portion of the second phononic cocrystals at the second side, which bonds the second impermeable barrier and backing to the second side.

2. A high resistance panel according to claim 1 wherein the impermeable barrier and backings are aluminum foils.

3. A high resistance panel according to claim 1 wherein the impermeable barrier and backings are metal plates.

4. A high resistance panel according to claim 1 wherein the surfaces of low emissivity are provided by aluminum foils.

5. A high resistance panel according to claim 1 wherein the first and second adhesives are clear and transparent glues of polyvinyl acetate.

6. A high resistance panel according to claim 1 wherein the first and second adhesives are hot melt adhesives.

7. A high resistance panel according to claim 1 wherein the first and second adhesives are pressure sensitive adhesives.

8. A high resistance panel according to claim 1 wherein the first and second phononic cocrystals are constituted from salt hydrates and fusion temperature-depressing salts.

9. A high resistance panel according to claim 1 wherein a total amount of the first phononic cocrystals and the second phononic cocrystals is 0.2 mg to 2 mg per cubic centimeter of the high resistance panel.

10. A high resistance panel according to claim 1 wherein the first phononic cocrystals at the first side are coated on surfaces of the honeycomb structure at the first side, and the second phononic cocrystals at the second side are coated on surfaces of the honeycomb structure at the second side.

11. A high resistance panel according to claim 1 wherein the thickness of the panel is 1 mm to 60 mm.

12. A high resistance panel according to claim 1 wherein the support material is paper.

13. A high resistance panel according to claim 1 wherein the honeycomb structure is made from sheets.

14. A high resistance panel according to claim 13 wherein the sheets have a thickness of 0.02 mm to 2 mm.

15. A high resistance panel according to claim 1 wherein the cross-sectional area of each honeycomb cell in a direction perpendicular to the longitudinal axis of each cell is 0.1 mm.sup.2 to 110.sup.6 mm.sup.2.

16. A high resistance panel according to claim 1 wherein the volume of each cell in the honeycomb structure is 0.1 mm.sup.3 to 10.sup.6 mm.sup.3.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a diagrammatic structure of HRP in the invention.

(2) FIG. 2 is a diagrammatic sketch showing one of the structures (hexagonal honeycomb structure) for support materials of HRP in the invention.

(3) FIG. 3 is a photograph of one of the structures (hexagonal honeycomb structure) for support materials of HRP in the invention.

(4) FIG. 4 is a photograph of one of the structures (regular cubic honeycomb structure) for support materials of HRP in the invention.

(5) FIG. 5 is a diagrammatic structure of two layers of HRP in the invention.

(6) FIG. 6 is a diagrammatic structure of three layers of HRP in the invention.

(7) The numbers in the FIGURES represent:

(8) 1. Impermeable barrier and backing 2. Surface of low emissivity coated with phononic cocrystals defined in the present invention. 3. Cell spaces in support materials. 4. Support materials. 5. Impermeable barrier.

DETAILED DESCRIPTION OF THE INVENTION

(9) VIP can provide low thermal conductivity for insulation. The keys in VIP are vacuum technology and microporous structure. Vacuum is a space that is devoid of matters, or a region with a gaseous pressure less than atmospheric pressure. In practice, the vacuum is partial vacuum. Less air molecules in voids of core materials of VIP eliminates heat conduction and convection by reduction in total kinetic energy of air molecules, or increase in the mean free path of air molecules (more space for molecules), therefore less collisions between air molecules. Heat transfer by radiation can be eliminated by micro scale of voids in VIP with microporous structure, provided that the sizes of voids are less than the mean free path of photons.

(10) In the present invention, the reduction in total kinetic energy of air or gas molecules is obtained by spatial continuous infinite structures of phononic cocrystals, as defined in the present invention, in which continuous infinite and infinitesimal voids exist. And the elimination in heat radiation is reached by low emissivity of material surfaces.

(11) Cocrystal is a crystalline structure made up of two or more components, where each component is defined as either an ion, an atom, or a molecule to form a joint super lattice, by a definite stoichiometric ratio between the components as each pure component has its own distinct bulk lattice arrangement. This includes many types of compounds, such as hydrates, solvates, clathrates, and eutectics, which represent the basic principle of host-guest chemistry. Spatial continuous infinite different structures of cocrystals are a mixture comprised of infinite different structures of cocrystals. The spatial continuity is defined to be as in an atomic or molecular level in stoichiometric ratio between different pure cocrystals. The different structures means that contiguous cocrystals are completely different in structures. In spatial continuous infinite structures of cocrystals there are very small voids between super lattices. The sizes of the voids are less than the mean free path of phonons. For convenient description, the cocrystals are named as phononic cocrystals or phononic eutectics, or photonic cocrystals. Phononic cocrystals represents all the names used in the context. It is shown from theory of thermal conductivity of matters that phonons can be scattered by crystal defects which reduce the thermal conductivity of crystals because the defects produce local variations of sound velocity through change in density or elastic constants. The defects in the phononic cocrystals provided by the voids greatly reduce the thermal conductivity to a very low level. The charge-acceleration and dipole oscillation by kinetic interactions among particles in the phononic cocrystals result in the electrodynamic generation of coupled electric and magnetic fields, which propagate as waves around the space surrounding the phononic cocrystals, and interfere with the matters (air or gases) in the space, reducing their total kinetic energy, and then resulting in a reduction in heat transfer.

(12) Heat radiation from a material through a space larger than optical depth is greatly related to the emissivity of material surfaces. A low emissivity of surface can eliminate heat transfer by radiation. Surface of foils of aluminum or its alloys has emissivity of 0.03 which is much less than most materials used for insulation. Surface of silver has a lower emissivity of 0.02-0.03 but silver is much more expensive.

(13) HRP in the invention overcomes the disadvantages of conventional insulation materials and VIP. HRP mainly includes the following improvements and modifications: (1) Phononic cocrystals provide a low thermal conductivity. (2) Reduction in kinetic energy of air or gas molecules in the spaces of support materials by the phononic cocrystals results in reduction in heat transfer. (3) Low emissivity of surfaces reduces heat transfer by radiation. (4) HRP can be cut to any sizes to meet requirements of installation. (4) No thermal bridging on edges. (5) HRP can stack or pile up to a thickness to meet requirements of installation and heat resistance.

(14) One embodiment of the present invention is shown in FIG. 1. A HRP consists of two impermeable barriers and backings 1, two surfaces 2 with a low emissivity facing each other in direction of heat transfer and coated with phononic cocrystals, support materials 4 for a structure and cell spaces 3.

(15) The materials for impermeable barrier and backing can be aluminum foils, metallised films which are polymer films coated with a thin layer of metal usually aluminum, metal plates, plastics laminated with metal films or by a means of deposition or coating, having very high impermeability and sufficient strength. Low emissivity of surfaces can be provided by aluminum foils or metallised films. The phononic cocrystals are mixed with a clear and transparent adhesive and coated on the surfaces. The adhesive can be glues made from polyvinyl acetate, hot melt adhesives, or pressure-sensitive adhesives. The adhesive also performs as a binder to glue the support materials to the surfaces. The support materials are natural fibres, glass fibres, rock wool, plastics, and other inorganic materials, and their mixtures, and made to form sheets, for example, paper sheets and the like, and then from sheets to form a honeycomb structure using the methods in the prior art. After sufficient strength has been considered, the thinner the sheets, the less heat transfer through the sheets.

(16) Honeycomb structures allow the minimization of the amount of support materials to reach minimal weight and maximum strength. A hexagonal honeycomb structure for support materials of HRP in the invention is shown in FIG. 2 and FIG. 3. A regular cubic honeycomb structure is shown in FIG. 4.

(17) The phononic cocrystals by the definition in the invention are a mixture of spatial continuous infinite different structures of cocrystals.

(18) The phononic cocrystals can be constituted from salt hydrates and fusion (melting) temperature-depressing salts that are generally non-hydrated salts in a high viscosity of polymer solution. A simple method and process are described as follows: (1) Mixing a salt hydrate with a fusion (melting) temperature-depressing salt at a ratio in a polymer solution. (2) Heating the solution to a temperature at which the salt hydrate and the fusion (melting) temperature-depressing salt melt completely. (3) Then gradually cooling the mixture without agitation to form the cocrystals. The high viscosity in the solution plays an important role in the process. The formation of phononic cocrystals in the process is induced by the spatial difference of ion concentrations in the solution with high viscosity. When the mixture is being cooled, a eutectic in a space is formed and the ions in the surrounding are being consumed. A different eutectic will be formed in the adjacent space, because the high viscosity reduces the ions to migrate to the space.

(19) The phononic cocrystals can also be formed from molten salts with different melting temperatures. The low melting point of salt provides high viscosity when heated to a molten status. The other salts with high melting points as powders are distributed in the molten salt. The mixture is heated to melt, then is gradually cooled without agitation to form phononic cocrystals.

(20) Furthermore, the phononic cocrystals can be formed from metal oxides during oxidation and water soluble salts where water acts as a catalyst. A simple example is that iron oxides from the oxidation of iron and sodium chloride constitute phononic cocrystals. Saturated solution of sodium chloride is mixed with iron powders and exposed to air or oxygen for oxidation while it is being cooled. The iron oxides formed absorb water, and sodium chloride crystals are seeded out with iron oxides to form eutectics. Due to the concentration gradients of sodium chloride spatially in the mixture, different eutectics are formed. In this process, the oxidation consumes oxygen in air. If the closed cells are formed by support materials, the absence of oxygen in air can produce partial vacuum in the cells, resulting in a reduction in total kinetic energy of air.

(21) The phononic cocrystals formed from the processes described above are not perfect because they are greatly dependent on the control of formation conditions. The perfect phononic cocrystals can be made by modern nano technology.

(22) The quantity of phononic cocrystals in HRP, coated on surfaces or mixed with support materials, depends on the structure and volume of honeycomb cells by the support materials. The thickness of HRP depends on the sizes of honeycomb structures, thickness and strength of sheets made from support materials, and strength requirement for the application. It is suggested that 0.2 mg to 2 mg of phononic cocrystals per cubic centimeter of total volume of HRP be appropriate for the purpose, preferably 0.5 mg to 1.5 mg. The thickness of HRP (in heat transfer direction) can be 1 mm to 60 mm, preferably 3 to 15 mm. The thickness of sheets made from support materials can be in a range of 0.02 mm to 2 mm, preferably 0.05 mm to 1 mm. The area of each honeycomb cell, perpendicular to heat transfer direction, can be in a range of 0.1 mm.sup.2 to 110.sup.6 mm.sup.2, preferably 1 mm.sup.2 to 110.sup.3 mm.sup.2. The volume of a cell in honeycomb structure made from support materials can be 0.1 mm.sup.3 to 10.sup.6 mm.sup.3, preferably 0.5 mm.sup.3 to 110.sup.5 mm.sup.3.

(23) Two or more HRP can be stacked or piled up to form a thickness to meet requirements for installation and heat resistance. FIG. 5 shows two layers of HRP stack, and FIG. 6 shows three layers of HRP stack. The impermeable barrier 5 between two HRP can serve the both.

(24) HRP in the present invention performs a low thermal conductivity that is in the order of 10.sup.3 w/(m.Math.K), thus providing high thermal resistance for insulation. HRP overcomes the disadvantages in VIP and conventional insulation materials, and can be made easily and at a low cost. HRP has a low density of 20-100 kg/m.sup.3, and can be cut to any sizes to meet requirements for installation.