Stock material or miscellaneous articles – Structurally defined web or sheet – Including aperture
Reexamination Certificate
1999-07-22
2001-06-26
Watkins, III, William P. (Department: 1772)
Stock material or miscellaneous articles
Structurally defined web or sheet
Including aperture
C428S464000, C428S137000, C428S131000, C428S132000, C428S138000, C156S253000, C052S408000, C052S409000, C052S411000
Reexamination Certificate
active
06251495
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to products having a low degree of emissivity, and to methods for producing same, and in particular to low emissivity products which also exhibit a high level of moisture vapor permeability.
As pointed out in U.S. Pat. No. 5,231,814 (“U.S. '814”), which is incorporated herein in its entirety by reference, and which is owned by the assignee of this patent application, roof decking typically is formed of structural wood products, such as plywood or oriented strand board (“OSB”). These structural wood products are attached to the structural members of a house by nails or other fastening means.
This roof decking defines the confines of the roof of the house and serves as the substrate for joining the outer protective water-shedding materials, i.e., the tar paper and shingles, which are attached thereto and complete the protective roof assembly.
This roof structure is formed of materials which inherently have minimal thermal insulating and emissivity barrier properties. Therefore, heat transfer through the roof structure from the outdoors to the interior space of, for example, a home, particularly during the summer months, is a problem to homeowner. Either a homeowner undergoes severe discomfort due to elevated temperatures inside the house, or they must pay a high price for installing and operating air conditioning.
Prior to the product described in U.S. '814, the insulative solar or heat emitting properties of a structural roof have undergone limited improvements such as by applying insulative materials to the exterior of the roof decking under the outer protective materials.
Excess heat transfer is generated on a daily basis in the summer months, which penetrates into the interstices of building materials such as sheet rock and insulation causing unwanted elevated temperatures within the interior living space.
Thus, under conventional home construction conditions, the air temperature in attics and ceilings can be raised to about 140 degrees F. or higher.
U.S. '814 addresses certain problems relating to heat transfer. In U.S. '814, a roof structure is fitted with roof decling comprising a sheet of plywood or OSB with a layer of foil material adhered thereto. The foil material comprises a layer of metallic foil such as an aluminum foil material. The foil material covers a roof decking material which in turn is fastened to rafters in a typical roof structure.
The foil material used in U.S. '814 includes a plurality of substantially uniformly distributed perforations which are preformed in the foil material prior to applying of the adhesive, and adhering same to the underlying substrate, i.e., OSB, plywood. The expressed reason for introducing the perforations into the foil material is to permit the passage of moisture between the moisture barrier layer and the roof In this way, it is thought that a significant portion of excess moisture can be released through the perforations located in the foil material thereby permitting the roof decking to “breathe.” If a significant portion of the excess moisture is not released, unwanted degradation of the substrate can result.
Moisture can be present due to, for example, water vapor which enters the house during construction (before the roof is put on), or after construction from roof leaks of various types. Unwanted moisture can also result from the cumulative effect of vapor condensation.
Typically, the decking is placed in position with the foil layer facing inwardly toward the attic of the house. The low emissivity foil faces at least one adjacent air space (the attic) to prevent unwanted heat transfer.
A partial sectional view of the roof decking structure is shown in FIG. 1 of U.S. '814. A plan view of the decking structure of FIG. 1 is illustrated in FIG. 2, which shows the perforations in approximately true scale. As shown in FIGS. 2 and 3, the perforations extend only through metallic foil 16 and not through the kraft paper 17 to which the foil is attached. The kraft paper is, in itself, capable of breathing. It is stated in U.S. '814 that kraft paper 17 need not be perforated, although perforations through or partly through the paper are not particularly detrimental. The kraft paper is provided for physical support of the foil during the handling, which precedes attachment of the foil material to the panel structure.
The density of perforations is in the order of 125 per square inch, although perforations in the range of from about 50 to about 160 per square inch are usable. Each perforation is about 0.06 mm or less in diameter.
SUMMARY OF THE INVENTION
It has now been discovered that the method of U.S. '814 forms a radiant barrier material covered product which exhibits certain performance limitations with respect to the structure of the U.S. '814 product.
It is generally recognized that openings in a radiant barrier sheet will increase the level of moisture vapor permeability from the radiant barrier covered substrate. However, it is recognized in the prior art that an increase in the size and/or number of the apertures in a radiant barrier sheet will lower the level of emissivity of the radiant barrier covered substrate.
In the method of the present invention, a radiant barrier covered substrate is formed by joining the radiant barrier covering to an underlying substrate. The joining operation can, for example, be accomplished by bonding the radiant barrier covering to an underlying substrate. This is typically done using an adhesive material as the bonding agent.
Applicant has recognized that various problems can occur in the formation process of U.S. '814 which adversely effects the structure described in U.S. '814. For example, when the radiant barrier layer is joined to the substrate using the previously described adhesive material and the method set forth in U.S. '814, a substantial number of the perforations located in the foil material can become wholly or partially plugged by the adhesive material. This plugging problem, when it occurs, limits moisture vapor permeability from the substrate thereby reducing the amount of excess moisture which can be transported through the perforations located in the foil material thereby constraining breathing of the roof decking.
Another problem in the method of U.S. '814 concerns overlay paper 17. Specifically, overlay paper 17 can undergo a substantial reduction in breathability.
This occurs after an adhesive material is applied and saturates the overlay paper 17. The above-described problems uncovered by applicants have been overcome by the methods and products of the present invention. Thus, the product of this invention is designed to exhibit a relatively high level of moisture vapor permeability, while also maintaining a low level of emissivity comparable to that which is described in U.S. '814. The product of the present invention effectively and efficiently deters the transfer of heat into the living space of the house during the summer months. At the same time, the subject product is designed to permit moisture vapor to be transported from the underlying substrate so that it will pass through the radiant barrier covering material via the apertures located therein. In this way, undesirable degradation of the underlying substrate, typically in the form of moisture-related decay, can be substantially reduced employing the subject method and product.
This invention is directed to a radiant barrier covered product. Typically, the product comprises a radiant barrier layer adhered to an underlying substrate. Preferably, the underlying substrate, which can be either structural or non-structural in nature, can be formed of a variety of materials such wood or wood substrate products, or mineral or polymeric substrate products. The underlying substrate is most preferably formed of a structural wood panel such as OSB, plywood or the like. The underlying substrate can also be selected from a group which includes moisture-containing substrates, permeable substrates, and s
Fang Yi Pygn
Wilson Elwin R.
Louisiana-Pacific Corporation
Marger & Johnson & McCollom, P.C.
Watkins III William P.
LandOfFree
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