Re-usable radiative thermal insulation

Abstract

Commercial metalized plastic film, in the form of discarded containers or container stock, is collected, cleaned, shredded and packaged, to produce an insulating layer having a high thermal resistance, or R-value, no outgassing of volatile compounds at habitable temperatures, and multiple reusability after deployment. Each step in the sequence is designed to minimize unit cost of the process, as well as maximize the thermal resistance of the finished product. The invention largely avoids disintegration of the recycled material, and hence utilizes the embedded energy already present in the construction of the original film.

Description

RELATED APPLICATION INFORMATION

[0001] This application claims priority from U.S. Provisional Patent Application Ser. No. 61/192,067, entitled "Re-usable radiative thermal insulation" and filed on Sep. 15, 2008, the disclosure of which is incorporated by reference in its entirety herein.

FIELD OF INVENTION

[0002] This invention relates to a thermal insulation for inhibiting heat losses from interior spaces. More particularly, this invention relates to collection, transformation, repackaging and deployment of a type of waste material to perform as a thermally insulating layer for an interior space. Most particularly, this invention relates to a collection, cleaning and shredding of metallized plastic films, and then repackaging and deploying the shredded product as an insulating layer for interior spaces.

BACKGROUND OF THE INVENTION

[0003] The U.S. Deptartment of Energy (DOE) recommends certain insulation performance for attics, walls, floors, etc. For the northern U.S. climates, for example, it recommends R-49 in the attic, and R-18 in the walls (where R-value represents thermal resistivity, which is the ratio of temperature gradient to heat flux, and is presented herein with units of .degree. F..times.ft.sup.2.times.hrs/(Btu.times.in). Thicker layers of conventional fiberglass batting (or using a blown-in version), totaling about 16 inches, can achieve the R-49 performance level. Above the ceiling rafters, there is usually no obstacle in achieving the attic targets. Walls present a far greater challenge; since both fiberglass and cellulose insulations have R-values of about 3 per inch, achieving R-18 requires wall cavities of about 6 inches in depth. Although the use of 2.times.6 framing, which has a 51/2 inch cavity depth, can approach this standard, replacement of the conventional 2.times.4 framing presents a prohibitively steep increase in construction cost, which discourages codification of this DOE guideline.

[0004] Today, R-18 is achievable in a 31/2 inch wall cavity with rigid or spray-in foam insulation products, which have R-values of nearly 6 per inch. However, there are at least three significant difficulties with this solution: (1) rigid foam board costs nearly 4 times as much per R-value as, for example, fiberglass batting, and spray-in foam is even more expensive; (2) the health consequence of slow volatile outgassing is a persistent concern of consumers, and contributes to slow acceptance of this technology; and (3) from a long term EPA perspective, foam products have poor recycling performance.

[0005] Cellulose insulation is a present-day example of insulating material derived from recycled products. A significant drawback is that cellulose is a biological food source, so it must be treated with insecticides and/or anti-fungal agents before being used. Whether or not these agents are a potential health hazard, they cannot avert biodegradation indefinitely, and are of more limited usefulness in humid climates. Despite the ecomomic advantages that cellulose enjoys over other products with respect to the enormous available volume of paper to be recycled, and the small amount of additional energy needed compared to that of fiberglass, the fact that fiberglass still maintains at least a 5 to 1 market advantage underscores the disadvantages of cellulose.

[0006] Metallized polyester film, primarily polyethylene terephthalate (PET) coated with aluminum, is widely used in the food industry for containers such as snack food bags. Freshness is preserved by taking advantage of aluminum's excellent diffusion resistance to oxygen and moisture. For example, Doritos Tortilla Chips by the Frito-Lay company alone account for more than 5 million bags sold each day in the United States. Considering the other products (potato chips, cookies, etc.), and other companies that currently utilize aluminized packaging, 20 billion bags per year is a conservative present-day estimate, and most of the used packages end up in landfills. Decomposition of plastics in this low oxygen and light-free environment has been estimated to be in excess of a million years.

[0007] Aluminized PET (Al-PET) and other metallized polyesters (e.g., aluminized Mylar) are also used in packaging by various other industries. Further, when one considers costs of the raw materials and film deposition processes used in manufacture, these containers add a significant cost in embedded energy to products, making the re-use of discarded bags with minimal added processing cost particularly attractive economically. The uncoated PET used for beverage containers is already being recycled to be used, for example, as plastic textile fibers. The feasibility of doing this owes partially to the identifiability of the waste items and their relative bulkiness per unit; on the other hand, absence of a metal co-laminate simplifies the process as well. The need to remove aluminum for re-use would add further cost for the Al-PET. Clearly there is need and incentive to find ways to reuse this valuable waste as is, in an environmentally sound fashion.

SUMMARY OF THE INVENTION

[0008] The present invention introduces a new approach to thermal insulation that is aptly labeled re-usable radiative insulation. Its insulative capability is superior to that of fiberglass and cellulose, and rivals that of high-end foam products. Moreover, the environmental impact of the present invention compares very favorably to any of the known alternatives; not only does the product of the invention use recycled material, but as a consequence of its biological inertness, the product has a long useful lifespan, presents no known health risks and is itself further recyclable.

[0009] In the present invention, discarded aluminized plastic bags are collected, batch-cleaned, batch-shredded, and disposed into the hollow cavities of building walls to provide thermal resistance. The reflective behavior of aluminized plastic film enables medium- to high-performance insulation layers to be produced to meet current and future needs. It is dust-free after shredding, and produces no significant outgassing over temperature ranges hospitable to life.

[0010] In another embodiment, specific volumes of the shreds are repackaged into sealed containers in the shape of substantially flat pouches, to be disposed into walls in a manner similar to fiberglass batting.

[0011] In another embodiment of the invention, the shreds, including containers which may package them, are recovered and repeatably used, without further processing other than possibly cleaning. Thus there is no intrinsic waste disposal issue with the product of the present invention; the property of aluminized plastic film that resists biodegradation, and which leads to such problems in the landfill arena, becomes an important asset in its use according to the present invention.

[0012] In another embodiment of the present invention, the geometry of the shreds is tailored to maximize thermal insulative capability. Shred shape (width, length, and edge patterning) and shred thickness affect the scattering properties of the IR light energy. Thickness of the plastic also determines stiffness (springiness), and so influences the free (unloaded) packing density of shreds.

[0013] In another embodiment of the present invention, the low specific weight and inherent springiness of the shreds results in a low free packing density, after which to which pressure is applied to the free-packed mass to achieve a greater packing density.

[0014] In another embodiment of the present invention, the geometry, packing density, and deployed layer thickness of the shreds is adjusted to be impermeable sub-terahertz radiation, including that of cellular phone signals and EMP (electromagnetic pulse), which is useful for building information security.

[0015] Another aspect of the invention is a high volume, batch cleaning process, using a mild detergent, to prepare collected waste material for shredding.

[0016] In another embodiment of the present invention, the thickness and packing density of the shreds are such that the layer impermeable to sub-terahertz radiation, especially cellular phone signals and electromagnetic pulse, which is useful for building information security.

[0017] Another aspect of the present invention is a supply chain for collection of aluminized plastic film to be processed, including: (1) the enlistment and adaptation of existing community, school and waste management industry recycling efforts (which already participate in cellulose collection); (2) the procurement of the unused part of factory production runs, such as cut-off waste and scrap; (3) production of aluminized plastic film directly for insulation purposes, to augment the supply from waste materials; (4) the engagement of manufacturers of products packaged in aluminized plastic, as a part of their "total supply chain" business models.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] FIG. 1 is a set of schematic illustrations to enable visualization of the quantitative working model that explains how the present invention works. FIG. 1A illustrates the model geometry. FIG. 1B is a diagram for development of a multiple reflection formula.

[0019] FIG. 2 is a cutaway drawing showing a section of an exemplary studded building wall, before and after deployment of the present invention, illustrating how shredded aluminized plastic film may be deposed into the wall's cavity spaces to fill them with an insulating layer.

[0020] FIG. 3 illustrates another embodiment of the present invention using containing pouches for the metalized plastic film shreds. FIG. 3A shows a section of an exemplary shred-filled pouch designed to fit the cavities of an exemplary studded building wall. FIG. 3B shows the insertion of said exemplary pouch into said exemplary wall.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

[0021] Although this invention will be described in terms of certain preferred embodiments, other embodiments that are apparent to those of ordinary skill in the art, including embodiments that do not provide all of the benefits and features set forth herein, are also within the scope of this invention. Accordingly, the scope of the invention is defined only by reference to the appended claims.

[0022] This invention provides thermally insulative layers for use in buildings and other applications where it is desirable to prevent the transmission of heat into or out of an interior space. An important aspect of the instant layers is that they have higher R-value than other commercial insulating layers of comparable cost, and may have R-value equal to, or greater than, commercial insulators of much greater cost.

[0023] A second important aspect of the instant layers is that they may be produced from certain common waste materials that lack biodegradability, and that have no other known intrinsic re-use value beyond their proximate purpose. Furthermore, the energy embedded in the original production of the waste materials used in the present invention is largely preserved in the instant layers. A third important aspect of the instant layers is that they do not present environmental burdens or hazards in the present invention.

[0024] Although cellulose insulation is produced from recycled paper products, its biodegradability and moisture affinity requires special treatment before deployment, limits its lifetime and climate compatibility, and precludes its further re-use. It also has a lower R-value than the instant layers. Foam insulation layers, either prefabricated or formed in situ (by spraying) may have higher R-values than the instant layers, but are more expensive, produce volatile outgassed contaminants while in service, cannot be subsequently re-used, and present a waste disposal problem at the end of their service life. Fiberglass wool is less expensive than foam, but has a similar end-of-life disposal problem; it also has a lower R-value than the instant layers. The generally superior performance of the instant layers is founded on the principles that we now describe.

Working Principle of Reusable Shredded Insulation

[0025] The key to efficient insulation is the management of thermal infrared radiation in a non-equilibrium manner. There are three mechanisms of thermal energy transport: conduction, convection and radiation. Contrary to conventional assumptions, conduction and convection are not dominant in insulating layers; the notion that the role of insulation is primarily to "trap small pockets of warm air" is a popular misconception. In reality, radiation dominates, whereby it is the role of insulation to trap and scatter infrared (IR) photons specifically.

[0026] The presence of greenhouse gases (GHG) in the atmosphere provides an illustrative example. Any sunlight that impinges on the earth that is not directly reflected is absorbed by it, and its energy converted into heat. This heat re-radiates back away from the earth, nominally propagating out into space, and cooling the earth while doing so. Passing through a less transparent atmosphere, however, the IR photons are intercepted by GHG's such as CO.sub.2, CH.sub.4, etc. The vibrational modes of these molecules, particularly their bending modes, coincide with the thermal blackbody energy which they absorb, and then reradiate. The reradiation of the thermal energy is in all directions, instead of exclusively outward. Thus part of this energy is re-directed back towards earth, causing earth to be warmer than if the thermal energy had been unimpeded.

[0027] Importantly, the GHG reradiation process does not occur in a thermal equilibrium. Although the temperature of the initial thermal radiation of the IR from the earth may have been, for example, at room temperature (about 20.degree. C.), and the temperature of the GHG molecules high in the atmosphere might be quite cold, for example, -50.degree. C., and these molecules are still quite effective in scattering. In the context of the present invention, it is not necessary for the scattering sites (i.e., insulator) to come into equilibrium with the incident thermal energy. In fact, ideally, we do not want it to reach equilibrium. It is better to elastically scatter or reflect this energy.

[0028] One of the limitations with conventional insulation is that it operates too close to thermal equilibrium, because its material (e.g., glass, cellulose, foams) is quite absorptive to IR photons. Absorption causes a small local temperature increase, and the resulting re-radiation leads to a net transmission forward, from the warmer side to the cooler. Each position within the insulation acts as a new source of thermal radiation. It is far better to reflect those IR photons by scattering back to the source without absorption, because after an elastic scattering event, that site will remain at its original temperature and no longer radiate a net amount of energy outwardly.

[0029] The glass in fiberglass has a reflectance of about 15%, averaged over the thermal band. Although not large, this is far greater than the organic materials contained in foams and cellulose, whose average thermal reflectances are in the neighborhood of 5 to 8%. In fiberglass matting, 15% intrinsic reflectance means that 85% of the incident power would have to be either transmitted through the glass or absorbed by it. As it happens, in this IR thermal region, most of the 85% is absorbed, and therefore contributes to local heating. Once this local heating occurs, it too acts as a new radiative source to further propagate the heat energy out to the next absorption site, and so on. So although this concatenation retards the transmission, the process of equilibrium local heating is a fundamental shortcoming in this sort of insulator.

[0030] By comparison, a non-equilibrium insulator should have superior insulation performance, because new radiation sources are not produced at each scattering site. Aluminum films in the thermal IR region have a reflectance of over 93%, meaning that only 7% of the energy can contribute to any local heating. In this regard, its vastly superior reflection performance over conventional insulation materials means that it can be effectively used as a non-equilibrium radiative insulation product.

[0031] Multilayers of aluminized films have been used for years in ultrahigh performance vacuum Dewars, which perform precisely because of the high reflectivity and low absorption (and so low emissivity) of the Al layers, while the vacuum minimizes conduction and convection. Such a multilayer configuration, however, is difficult to implement in a construction setting. Instead, we use shredded reflective plastic material to back-fill the wall cavity, as an approximation of the Dewar principle. In this case, it is better to think of "scattering" events of thermal IR radiation from the random shreds, rather than reflection events from uniform films.

Quantitative Model

[0032] A simple quantitative model can be developed to describe our non-equilibrium radiative insulation. Although we have indicated the relative importance of radiation over thermal conduction and convection, the latter two must be accounted for, because our product is not in a vacuum. All three transport processes occur in parallel (collaterally). It happens that structural details can be assumed to allow us to (mostly) neglect the role of convection and we can gain considerable insight by considering radiation and thermal conduction alone through the air medium. Our goal is to be able to mathematically describe, in a general way, a reflective plastic that is shredded, and hence forming a disordered array of reflectors. We start by considering two radiative and parallel surfaces that are separated by a thermally conductive medium. We then show how this result can be incorporated into a simple model that takes the disordered reflective shreds into account.

[0033] Air happens to have a fairly poor thermal conductivity (0.0256 W/m/.degree. C. at 21.degree. C., as given by the CRC Handbook of Physics and Chemistry, CRC Press, Boca Raton, 1980). To enable comparisons, we convert this into the English thermal system of units used in the United States. Inverting this conductivity to a thermal resistance, or "R-value", leads to a resistance density or resistivity (i.e., per inch) value of 5.63.degree. F.ft.sup.2Hr/Btu/inch. It is a rather surprising fact that this R-value compares quite favorably with some of the best foams, which have 5 to about 7 per inch. Since air is such a good thermal resistor, one may wonder why we even need to displace it with other insulation. The answer is that without solid matter present, radiative and convective processes dominate: IR radiation propagates directly through air, and its fluidity supports convective currents.

[0034] The starting point in any thermal model is the power transferred by thermal conduction,

.DELTA. P c = A .kappa. .DELTA. T .DELTA. x , ( 1 ) ##EQU00001##

where A is the cross sectional area, .kappa. is the thermal conductivity of the medium, which has a temperature difference .DELTA.T and a distance .DELTA.x between the hot and cold ends. This can also be expressed in terms of the thermal "resistance" to conduction, which is defined by R.sub.c.ident..DELTA.x/.kappa.,

.DELTA. P c = A R c .DELTA. T . ( 2 ) ##EQU00002##

[0035] The power radiated by any warm body (j) is given by the blackbody expression

P.sub.rad=A.sigma..epsilon..sub.jT.sub.j.sup.4, (3)

according to its absolute temperature T, surface area A, surface emissivity .epsilon..sub.j, and the Stefan-Boltzmann constant .sigma.. In order to understand how to combine the effects of conduction and radiation, we refer to schematics of FIG. 1. In FIG. 1A, there is shown a model volume 10 that is bounded by a first plate 11, having an area A, temperature T.sub.1 and emissivity .epsilon..sub.1, and a second plate 12, having the same area A, but a different temperature T.sub.2 and emissivity .epsilon..sub.2. Plates 11 and 12 are separated by a distance 13 equal to .DELTA.x.

[0036] For conduction, the plate separation 13 is an important parameter, but it is immaterial to radiation, in the limit of infinite plane boundaries. The plates emit blackbody energy by virtue of having temperatures above absolute zero. Thus for radiation, we consider each plate to be a source, where plate 11 emits the rightward beam 14, having an intensity value of I.sub.01, and plate 12 emits the leftward beam 15, having an intensity value of I.sub.02.

[0037] In FIG. 1B, we show diagrammatically from a side view how the energy that is first emitted from plate 11 makes multiple reflections 16 at plate 12, and re-reflections 17 at plate 11. Reflections 16 and 17 have reflectance values R.sub.1 and R.sub.2, respectively. Each interaction with plate 12 also results in partial transmission 18 through it. Adding all of these terms results in an infinite series to arrive at the total amount of power flowing from plate 11 through plate 12,

T.sub.12=I.sub.01(1=R.sub.2)[1+(R.sub.1R.sub.2)+(R.sub.1R.sub.2).sup.2+ . . . ],

which converges to

T 12 = I 01 ( 1 - R 2 ) 1 - R 1 R 2 . ( 4 a ) ##EQU00003##

Similarly, the net flow of power from plate 12 through plate 11 is

T 21 = I 02 ( 1 - R 1 ) 1 - R 1 R 2 . ( 4 b ) ##EQU00004##

[We caution that our adoption of the standard optics notation R.sub.1, R.sub.2, T.sub.12 for reflectance and transmittance not be confused with the notation we use throughout for R-values and temperatures.] We now make use of the fact that the emissivity and reflectance are related (by definition) according to

R.sub.j=1-.epsilon..sub.j. (5)

Since the incident intensities (I.sub.0j) are given by Eqn. (3), Eqns. (4) and (5) can be combined to give the total net flow of energy to the right as .DELTA.P.sub.12=T.sub.12-T.sub.21, or

.DELTA. P 12 = A .sigma. ( T 1 4 - T 2 4 ) ( 1 1 + 1 2 - 1 ) = A .sigma. ( T 1 4 - T 2 4 ) 1 12 , ( 6 ) ##EQU00005##

in terms of the temperatures (T.sub.j) of the two plates, and where we have defined an effective inverse emissivity <I/.epsilon..sub.12>. It should be noted that this equation is independent of the separation between the two plates. A similar expression is given in Solar Heating and Cooling, by J. F. Kreider and F. Kreith (McGraw, New York, 1975), p. 17.

[0038] In order to compare with conduction processes, we would like to use the same type of formalism for the radiation as is used in conduction in Eqn. (1). In other words, we would like to consider the interior space to be a "black-box" of unknown processes. For our purpose, we suppose that the internal energy transfer mechanism is by a conduction process (even though we know it is a radiation process). In this way, we will be able to obtain the effective "resistance" to radiation energy transport (R.sub.rad) and obtain an expression similar to Eqn. (2), i.e.,

.DELTA. P rad = A R rad .DELTA. T = A R rad ( T 1 - T 2 ) . ( 7 ) ##EQU00006##

It is also convenient to express (T.sub.1.sup.4-T.sub.2.sup.4) in Eqn. (6) as

( T 1 4 - T 2 4 ) = ( T 1 - T 2 ) 4 T 1 3 ( 1 - 3 4 .DELTA. T T 1 ) ( 8 ) ##EQU00007##

because we would like to eliminate the .DELTA.T term in Eqn. (7). Therefore, since we force .DELTA.P.sub.rad=.DELTA.P.sub.12, Eqns. (6) through (8) give us the effective R-value for radiation resistance:

R rad = ( 1 + 2 - 1 2 .sigma. 1 2 ) 1 4 T 1 3 1 ( 1 - 3 4 .DELTA. T T 1 ) . ( 9 ) ##EQU00008##

In Table 1, we have calculated effective radiative R-value vs. emissivity for the two thermal surfaces 11 and 12, assuming their temperatures are 40 C and 20 C, respectively. Values for .epsilon..sub.2 of about 0.94 are typical of most building materials, and .epsilon..sub.1 of 0.1 is approximately that of a shiny Al surface. We also see that the effective R-value for radiation is about 0.9, i.e., quite a bit lower than the 5.63 per inch for thermal conduction through air, as noted above. In other words, more than 6 (=5.6/0.9) times as much energy flows out from a warm body by IR radiation than by kinetic transport through collisions by air molecules.

[0039] Since parallel conductivities are additive, resistivities add reciprocally, we have

1 R effective = 1 R cond + 1 R rad , ( 10 ) ##EQU00009##

so we find that the effective R-value for air is only about 0.78. Such a low R-value agrees with our subjective experience, but we have now shown that the major reason for this is the simultaneous flow of substantial energy in the form of infrared radiation.

TABLE-US-00001 TABLE 1 emissivity .epsilon..sub.1 .epsilon..sub.2 R.sub.rad (ft.sup.2-.degree. F.-hr/Btu) 1.00 1.00 0.858 0.94 0.94 0.967 0.50 0.94 1.770 0.20 0.94 4.343 0.10 0.94 8.632 0.10 0.10 16.296

[0040] To check the validity of this calculation, we can derive a result that is specified on a commercially available product. The Dow company markets a product called Super-Tuff-R.TM., which is a rigid polyisocyanate foam insulation board having aluminum on one side, and whose basic R-value is 6.5/inch. Dow states that an additional R of 2.8 can be achieved when the Al side faces a 3/4 inch non-ventilated air gap, i.e., when no physical contact is made to the Al surface. Under this condition, the system R-value can be 9.3 for a 1 inch board with the 3/4 inch air gap. Since R.sub.cond=R.sub.air(0.75'')=0.75.times.5.63=4.22, if we use R.sub.rad=8.63 from Table 1 that is appropriate for Al on one side and drywall on the other side of the air gap, Eqn. (10) predicts an effective R-value of 2.83.

[0041] Now that we have a solid understanding of parallel radiative plates separated by a distance .DELTA.x in a thermally conductive medium, we will generalize in a simple way to the random shreds. The key is that this same process should still be approximately valid on a local level. Thus in describing the shreds, we really only need to know the "resistance density" between two typical scattering sites, which is commonly known as the resistivity (.rho.), i.e.,

R.sub.j.ident..delta.x/.kappa..sub.j=.delta..times..rho..sub.j, (11)

where for air, .rho..sub.air is 5.63 per inch (at 20.degree. C.). Combining Eqns. (10) and (11), we obtain the effective thermal resistivity for a random packing of reflective shreds as

.rho. effective = .rho. air R rad .delta. x .rho. air + R rad , ( 12 ) ##EQU00010##

having units of [.degree. F.ft.sup.2 Hr/Btu/inch] and where we can understand that .delta.x represents an average effective separation between the shreds that will be governed by such things as packing density, general shape, etc. Another way to look at it is that it represents an effective scattering length. All of the emissive dependencies will be contained in R.sub.rad as described by Eqn. (9). Table 2 summarizes calculated effective thermal resistivities for different values of surface emissivities taken from Table 1. As expected, as the scattering length approaches zero, .rho..sub.effective approaches .rho..sub.air.

[0042] Table 2 is a summary of our non-equilibrium model, showing effective thermal resistivity vs. scattering length (.delta.x) for the different surface emissivities taken from Table 1. demonstrates that by using reflective shreds, medium to high performance insulation is obtained, having R-values greater than 3 and less than 5.6, where the upper limit is imposed by the thermal resistivity of air, which is 5.63 per inch at 20.degree. C.

TABLE-US-00002 TABLE 2 .epsilon..sub.1 0.94 0.50 0.20 0.10 0.10 .epsilon..sub.2 0.94 0.94 0.94 0.94 0.10 R.sub.rad 0.967 1.770 4.343 8.632 16.296 .delta.x (in.) .rho..sub.effective (.degree. F. in.sup.-1 ft.sup.2 Hr Btu.sup.-1), i.e., R per inch 0.000 5.63 5.63 5.63 5.63 5.63 0.063 4.13 4.70 5.21 5.41 5.51 0.125 3.26 4.03 4.85 5.21 5.40 0.250 2.29 3.14 4.25 4.84 5.19 0.500 1.44 2.17 3.42 4.25 4.80 0.750 1.05 1.66 2.86 3.78 4.47 1.000 0.83 1.35 2.45 3.41 4.19

Preferred Embodiments of the Invention

[0043] All of the preferred embodiments of the instant invention share an important first common element of collection of raw material according to a supply chain business model, and said model is included as part of the claims. Aluminized plastic film for the instant invention is supplied at least three different sources. A first source is the waste stream of discarded packages, where it appears in increasing amounts, and is becoming a landfill space allocation problem, due to its slow biodegradation. To collect from this source, enlistment of volunteer efforts are used, coupled with two types of industrial cooperation: (1) participation by waste collection companies in the form of classification and separation by customers as a recyclable waste type, and (2) participation by product suppliers who use aluminized plastic film packages, in the form of cash incentives for the return of the emptied packages, with the cost either absorbed as a community service or compensated in part by the producer of the instant invention. A second source of aluminized plastic film is scrap incurred in the processes of manufacturing said film itself, fabrication of packages from said film, filling said packages with salable products, or distribution of said products. In the sequence of these activities, there is a considerable amount of scrappage, resulting from cut-off waste, process control, and product control, for examples. In these cases, it is advantageous to coordinate with whole product supply chains of vendors. A third source of aluminized plastic film is the manufacture of the film specifically for the purpose of production of thermal insulation layers according to the instant invention. Although this source lacks the environmental synergy of the waste sources, it serves to augment what could become a limited supply, and also removes the costs of cleaning and shredding. Said avoidance of shredding may be effected by drawing the plastic film into narrow strips that are equivalent to shreds, and applying the metal coatings to the strips.

[0044] In a first embodiment of the instant invention, aluminized plastic film collected from the public waste stream is subjected to cleaning of extrinsic material that would preclude its successful processing or deployment according to the invention. Said cleaning is performed in a batch process, consisting of (1) a first step of agitation of a plurality of Al-plastic packages in a vat of water and a mild detergent; (2) a second step of rinsing in a sequence of tanks, said rinsing using either a cascade or a dump configuration; and (3) a third step of drying, using forced air and tumbling configurations, for example.

[0045] In a further embodiment of the instant invention, dry aluminized plastic sheets and packages are cut into narrow strips by a shredding process. Said shredding process may be effected using a dedicated paper-shredding means, or another design. Means may be employed to prevent buildup of softened plastic on the cutting edges.

[0046] A particular preferred embodiment of the instant invention is illustrated in FIG. 2, wherein the invention serves as insulation for a studded building wall. FIG. 2A shows a cutaway of a section 20 of a wall, with two sheets 21 separated by stud spacers 22. Aluminized plastic film shreds 23 that may have been collected, cleaned and shredded according to embodiments described herein, are shown being placed into a hollow cavity space 24 formed by the structure. FIG. 2B shows a cutaway of the same section 20 at a later time, wherein cavity space 24 has been completely filled with shreds 23 to a desired packing density, to form a collective layer 26, which is also a thermally insulating layer.

[0047] Another preferred embodiment of the instant invention is illustrated in FIG. 3, wherein the invention serves as insulation for a studded building wall. FIG. 3A shows a pouch 36 that is filled with a plurality of aluminized plastic shreds 33 to a desired packing density, and then sealed. The pouch 36 has substantially a shape that enables it, when filled, to fit into, and substantially conformally fill, a cavity space for which it is intended. FIG. 3B shows a cutaway of a section 30 of a wall, with two sheets 31 separated by stud spacers 32. Pouch 36, filled with shreds 33, is shown being inserted into the hollow cavity space 34 formed by the wall structure.

[0048] In a preferred embodiment, the pouch 36 of FIG. 3 is constructed of metallized plastic film.

[0049] In a further preferred embodiment, the embodiments shown in FIG. 2 and FIG. 3 are combined, so that the pouch 36 is first inserted into cavity space 34, and then loose shreds 23 may be added to occupy remaining unfilled regions in the cavity space 34.

[0050] In a further embodiment, loose shreds of aluminized plastic film in FIG. 2 and FIG. 3 are blown into the hollow cavity spaces 24 and 34 in a similar fashion as is cellulose insulation or loose fiberglass insulation.

[0051] In another preferred embodiment, at the end of the life of a building insulated according to the instant invention, loose aluminized plastic shreds are removed from the walls by a suitable vacuum apparatus, and intact pouches are extracted, the recovered shreds and packages are cleaned and repackaged, if appropriate, and used in another building.

[0052] Those skilled in the art will appreciate that the methods and designs described above have additional applications and that the relevant applications are not limited to those specifically recited above. Also, the present invention may be embodied in other specific forms without departing from the essential characteristics as described herein. The embodiments described above are to be considered in all respects as illustrative only, and not restrictive in any manner.

Claims

1. A method for providing thermal insulation comprising: obtaining metalized plastic film; shredding said metalized plastic film; disposing said shredded metalized plastic film between a first surface and a second surface.

2. The method of claim 1, wherein said first surface and said second surface form a portion of a boundary, said boundary enclosing or partially enclosing a volume space.

3. The method of claim 2, wherein said volume space is a building or a room within said building.

4. The method of claim 2, wherein said volume space is a portable living space.

5. The method of claim 2, wherein said volume space is a vehicle.

6. The method of claim 2, wherein said volume space is a container.

7. The method of claim 1, wherein said metalized plastic film is a waste product.

8. The method of claim 7, wherein said metalized plastic film waste is a discarded package of a perishable commercial product.

9. The method of claim 7, wherein said metalized plastic film waste is the cut-off waste or scrap waste incurred in the manufacture of metalized plastic film and packages for perishable or light-sensitive products.

10. The method of claim 7, wherein said metalized plastic film waste is cleaned before said shredding.

11. The method of claim 7, wherein said obtaining includes collecting said metalized plastic film waste from a recycler.

12. The method of claim 7, wherein said obtaining includes collecting unused waste and scrap from package manufacturers.

13. The method of claim 1, wherein said metalized plastic film is shredded into strips having widths of between 1 millimeter and 1 centimeter and having random lengths.

14. The method of claim 1, wherein said metalized plastic film is shredded into strips having selected widths and selected lengths according to predetermined mathematical distribution formulae.

15. The method of claim 1, wherein said metalized plastic film is aluminized plastic film waste.

16. The method of claim 1, wherein the space between said first surface and said second surface is substantially filled with said metalized plastic film.

17. The method of claim 1, further comprising adjusting the amount of said metalized plastic film disposed between said first surface and said second surface to achieve a predetermined thermal resistance.

18. The method of claim 1, wherein said disposing includes placing said shredded metalized plastic film in a pouch and disposing said pouch between said first surface and said second surface.

19. A thermal barrier, comprising: a first surface layer and a second surface layer, with a hollow space in between; and an insulating material disposed within said hollow space, wherein said insulating material comprises shreds of metalized plastic film.

20. The thermal barrier of claim 19, wherein said thermal barrier is a wall.