Patent Application
20050260904
The present invention relates generally to a laminate which is used in preventing the infiltration of air and bulk moisture into the interior of a building, including walls, roofs and as window flashing, and as a component in vehicle envelope protection from moisture and corrosive agents.
Protective wraps are used throughout the construction industry to prevent against air infiltration and damaging moisture build-up in residential and commercial construction. As materials used for preventing the infiltration of air and bulk moisture to the interior of a building, polymer-coated papers and water-resistant sheathing materials are well known, with breathable materials which prevent the infiltration of air and bulk moisture into the interior of a building while allowing the outward passage therethrough of moisture vapor being particularly popular.
Breathable materials are usually formed from a flexible or rigid substrate having a polymer layer provided thereon which has been mechanically or electrically perforated, embossed, stretched or otherwise mechanically worked to form passages therein which are small enough to prevent the flow of air and water therethrough but large enough to allow the passage of water vapor and are provided in the form of woven, perforated and microporous building wraps. However, these types of conventional breathable materials have problems in the formation of passages which have to strike a balance between being small enough to prevent the flow therethrough of air and bulk moisture but large enough to allow the passage of moisture vapor therethrough. In certain situations, these conventional breathable materials can allow the passage of bulk moisture from an outside surface to the interior surface thereof, particularly if the bulk moisture is contaminated with a surfactant.
Roofing systems typically contain underlayment to aid in the drainage of moisture off the roof and help block the permeation of bulk moisture into the interior of the roofing system. Although some “breathable” underlayments are currently being used, the manufacture of them are so expensive as to be cost-prohibitive in some applications.
Recreational vehicles typically have undersiding applied thereto to protect the underside of the recreational vehicle from bulk moisture intrusion and corrosive agents and allow moisture vapor to escape. The current materials being used as vehicle undersiding include non-perforated woven polymers, galvanized steel, molded plastic sheets and woven polymer laminates. However, none of these materials both effectively prevent bulk moisture intrusion and allow moisture vapor to escape.
Flexible flashing is adhered around window flanges and jambs as strips of material between 4 and 24 inches wide to prevent bulk moisture intrusion and allow moisture vapor to escape. Flexible window flashing such as asphalt-saturated organic Kraft paper, polymer-coated reinforced organic Kraft paper and SBS-modified asphalt having polymer-based films provided on a surface thereof are typically adhered around window flanges and jambs using conventional sealants. These conventional flexible flashing have problems with respect to their inability to allow moisture vapor to escape from the wall cavity around windows and doors and effectively withstand bulk moisture penetration.
U.S. Pat. Nos. 6,133,168 and 6,541,072 to Doyle et al disclose coated substrates having a moisture vapor transmission rate greater than about five perms which are formed from a substrate, a monolithic, extrusion coated breathable polymer layer and a primer layer provided between the substrate and used in the construction industry for preventing the infiltration of air and bulk moisture while allowing the outward passage of moisture vapor. However, these coated substrates tend to be fairly expensive due to the complicated process needed for the formation thereof and can lack sufficient tear and tensile strengths.
U.S. Pat. No. 6,550,212 to Lubker, XII discloses a protective drainage wrap made up of a first portion comprising cross-woven or cross-laminated materials in the machine direction and in the transverse direction, with the material in the transverse direction having a thickness at least two times greater than the material in the machine direction, and a second portion comprising a coating or a solid sheet portion provided on the first portion. The first portion aids in the drainage of moisture build-up while open interstices/spaces in the first portion allow for natural vapor transmission. As the solid sheet portion, a breathable film is disclosed. The protective drainage wraps of U.S. Pat. No. 6,550,212 have a problem in that although they allow the transmission of moisture vapor to the outside of the wraps, there is also the possibility of bulk moisture transmission from the outside to the inside of the wraps.
A first embodiment of the present invention is directed to a laminate having a moisture vapor transmission rate greater than one perm and comprising an open mesh fabric having a monolithic liquid barrier and vapor permeable coating provided on a surface thereof.
In a second embodiment of the present invention, a substrate of a non-woven thermoplastic fabric, foam layer, organic Kraft paper or organic felt paper is provided on an opposite surface of the open mesh fabric of the first embodiment.
In a third embodiment of the present invention, the monolithic liquid barrier and vapor permeable coating is provided between and adhered to the open mesh fabric and the substrate of a non-woven thermoplastic fabric, polymeric foam layer, organic Kraft paper or organic felt paper.
Another embodiment of the present invention is directed to a roofing system containing a laminate according to either the first, second or third embodiments of the present invention.
A fifth embodiment of the present invention is directed to a recreational vehicle undersiding comprising a laminate according to either the first, second or third embodiments of the present invention.
A sixth embodiment of the present invention is directed to a window flashing comprising a laminate according to either the first, second or third embodiments of the present invention.
Another embodiment of the present invention is directed to a method of preventing the infiltration of air and water to the interior of a building structure which comprises the steps of incorporating into the building structure a laminate according to the first, second or third embodiments of the present invention.
An eighth embodiment of the present invention is directed to a building structure which comprises a laminate according to the first or second embodiment attached to at least one framing member.
The laminates of the present invention are lightweight, have a high strength and are capable of providing an effective moisture vapor transmission rate therethrough while being an effective liquid and moisture barrier.
As illustrated in
Although an open mesh thermoplastic fabric 2 is shown in the figures and is thermally bonded, the present invention is not limited thereto and woven, non-woven, knitted and molded thermoplastic, glass, graphite, acrylic and polycarbonate fabrics having an “open mesh” configuration where spaces 6 are formed between the fabric's strands or fibers 4,5 are interchangeable in the present invention for the open mesh thermally bonded thermoplastic fabric. The woven and non-woven thermoplastic fabric is preferably made of a polyolefin, a polyester, a polyamide or mixtures or blends thereof and has a weight of at least five grams per square meter. The open mesh thermally bonded thermoplastic fabric 2 is formed from vertical strands of a thermoplastic fabric 4 and horizontal strands of a thermoplastic fabric 5 thermally bonded to each other and has a weight of at least five grams per square meter. The open mesh thermally bonded thermoplastic fabric 2 is preferably made of a polyolefin, a polyester, a polyamide or mixtures or blends thereof. Spaces 6 are formed in the open mesh thermally bonded thermoplastic fabric 2 between the vertical strands 4 and the horizontal strands 5.
Alternatively, the strands of the open mesh thermally bonded thermoplastic fabric 2 can run in the diagonal direction with respect to each or any other manner as long as crossing strands are thermally bonded to each other and spaces 6 are provided in the fabric 2. Additionally, the configuration of the strands 4,5 is not critical as the thickness and width of either strand can vary in any direction and the strands 4,5 can have flat, square, triangular, circular, etc., cross-sectional areas.
The monolithic liquid barrier and vapor permeable coating 3 is substantially impermeable to bulk moisture but has a molecular structure which enables moisture vapor to pass therethrough. The monolithic liquid barrier and vapor permeable coating 3 is formed from conventionally known permeable resins such as copolyesters, polyesters, polyurethanes, acrylic polymers, polyethers, ester-ether copolymers as well as blends and copolymers thereof. The combined thickness of the monolithic liquid barrier and vapor permeable coating 3 is not critical and can be approximately 1 mil or thicker and preferably is approximately 1 mil. A particularly preferred breathable polymer is a copolyester.
The monolithic liquid barrier and vapor permeable coating 3 can be applied to the open mesh fabric by any suitable means such as laminating as a film onto the fabric 2 or extrusion coating the monolithic liquid barrier and vapor permeable coating 3 directly onto the open mesh thermoplastic fabric 2.
In order to enhance bonding between the open mesh fabric 2 and the monolithic liquid barrier and vapor permeable coating 3, the fabric 2 can be subjected to corona discharge treatment according to well-known procedures. It is believed that the corona discharge treatment chemically roughens the surface of the fabric 2 to enable a stronger bond to be formed between the fabric and the coating 3.
An alternative method of laminating the open mesh thermoplastic fabric 2 to the substrate (non-woven, felt, Kraft or foam) is to co-extrude two layers of the breathable resin, one on the surface of the open mesh fabric and one on the adjacent side. Co-extrusion methods for coating the open mesh fabric 2 and laminating the open mesh fabric 2 to the substrate are well known in the art. With the present invention, there is no need for an intermediate “primer layer” as satisfactory adhesion is provided between the open mesh thermoplastic fabric 2 and the monolithic liquid barrier and vapor permeable coating 3. Lamination techniques for adhering thermoplastic materials together are well known and can be used in the present invention as are processes for the extrusion coating of a layer of a polymer onto a supporting substrate and laminating the plies together.
A second embodiment of the present invention is illustrated in
The non-woven thermoplastic fabric 15 can be spun-bonded, stitch bonded, needle punch, slit film or melt-blown thermoplastic material and can be used individually, in laminates of each other or as components in a laminate. The non-woven thermoplastic fabric can be subjected to special calendaring processes, spot-welding, etc. to improve its physical properties. The open mesh fabric, non-woven thermoplastic fabric and the organic Kraft and felt paper 15 can be treated by methods well known in the art to improve the exposed surface stability thereof. The non-woven thermoplastic fabric, organic Kraft paper and organic felt paper 15 preferably have a weight of at least one ounce per square yard. The polymeric foam layer can be naturally permeable to the flow of air and moisture vapor therethrough or the desired permeability can be obtained by perforating, special calendaring or otherwise mechanically working the foam layer 15. The polymeric foam layer 15 can be formed from polystyrene, polyurethane or a urethane derivative and has a density of from about 0.5 to 3 pounds per cubic foot.
In a preferred embodiment of the present invention, the monolithic liquid barrier and vapor permeable coating 12, open mesh thermoplastic fabric 11, and substrate 15 are extrusion coated such that the monolithic liquid barrier and vapor permeable coating 12 melts, fills the spaces 6 between the vertical strand 13 and the horizontal strand 14 of the thermoplastic fabric and adheres directly to the substrate 15.
Alternatively, as shown in
As shown in
The laminates of the present invention can also be used in roofing systems as an underlayment, as an undersiding for a recreational vehicle and as a window flashing adhered around window flanges and jambs. In all of these utilities, the inventive laminates function to prevent the intrusion of air and bulk moisture yet allow the outward passage of moisture vapor.
