Patent Application
20060199453
1. Field of the Invention
This invention relates to a composite roofing membrane having a top layer of a thermoplastic polymer, a middle layer of a fleece material, and a bottom layer of a modified bitumen. More particularly, the invention relates to a composite roofing membrane in which the top and bottom layers are reinforced with a polymer/glass scrim and methods of preparation thereof.
2. Description of Related Art
Single ply roofing membranes to cover flat and pitched roofs are known in the art of commercial roofing membranes. Some membranes comprise bottom and top polyolefin-based sheets with a fiber reinforcement scrim sandwiched between the sheets. To promote adhesion between the scrim and the polyolefin sheets, a highly flowable, functional-polyolefin is incorporated into one or both sheets as disclosed in U.S. Pat. No. 6,544,909.
Other membranes of the prior art consist of materials based on atactic polypropylene (APP) modified bitumen. Still other membranes consist primarily of materials based on styrene-butadiene-styrene (SBS) modified bitumen. Attachment of these membranes to underlying roof decks are accomplished with adhesives and/or screws. To adhere one membrane to another membrane to render the roof covering waterproof, the selvage edge of one membrane is overlapped with the selvage edge of the next membrane. A torch is then used to soften the membranes at their overlapped portions to achieve a seam sufficient to withstand weather conditions.
U.S. Pat. No. 6,134,856 discloses a roll roof membrane, and a method for its preparation, which obviates the use of a torch to achieve a seam between the overlapped portions of the membranes. The roof membrane comprises a support sheet having bonded on the top and bottom surfaces thereof layers comprising APP modified bitumen, a first selvage edge disposed in the top APP modified bitumen layer along one side of the membrane, a second selvage edge disposed in the bottom APP modified bitumen layer along the opposite side of the membrane, and wherein each of the selvage edges have a series of embossed ridges and valleys adopted to accept adhesives, the valleys extending substantially through the APP modified bitumen layers to the support sheet.
The method of preparing the roll roof membrane includes the steps of: a roll of support sheet is unwound and passed through an accumulator; the unwound sheet is dip coated by immersion in a coating vat containing molten compounded APP, asphalt, and one or more fillers and fire retardants; while the coatings are in a molten state, the selvage edge of the membrane is contacted with top side embosser; the APP modified bitumen layers are dried, cooled and solidified by floating the membrane in a water bath and the membrane is wound into a roll. A suitable liquid parting agent, such as a coconut oil, can be added to the bottom surface of the membrane to reduce the tendency for the membrane to stick during winding and subsequent handling.
In accordance with the present invention, there is provided a composite roofing membrane for covering industrial and commercial flat and pitched roofs. The composite roofing membrane is characterized by the presence of a fleece material made of polyethylene or polyester having soft piles on its top and bottom surfaces with interstices therebetween to secure a top layer and a bottom layer thereto without the use of an adhesive or other securing means. Within this broad concept, the present invention includes two preferred embodiments.
The first embodiment of the composite roofing membrane comprises:
a top layer of a thermoplastic polymer, such as a thermoplastic polyolefin including the members selected from the group consisting of polyethylene, polypropylene, terpolymers of ethylene, propylene and diene monomers, ethylene-propylene copolymers, ethylene-butane copolymers, ethylene-hexane copolymers, ethylene-octane copolymers, propylene-C4-8 alpha olefin copolymers, metallocene polyolefins, and polyvinyl chloride;
a middle layer of a fleece material, preferably made of polyethylene or polyester having soft, deep piles on the top and bottom surfaces thereof with interstices therebetween to allow the top and bottom layers in molten flowable form to flow therethrough; and
a bottom layer of modified bitumen composite wherein the modifier is selected from the group consisting of atactic polypropylene (APP), styrene-butadiene-styrene (SBS), styrene-ethylene-butadiene-styrene (SEBS), and styrene-butadiene rubber (SBR).
In another embodiment of the present invention both the bottom and top layers are reinforced by a reinforcing scrim or sheet fabricated from fiberglass, polyester, or fiberglass reinforced polyester. The scrim or sheet is preferably positioned in the middle of the layers, and typically has a thickness of from about 0.05 mm to about 0.5 mm.
Preferably, the composite roofing membrane contains a selvage edge disposed in the bottom layer along one side of the membrane for facilitating the positioning of two membranes laid down longitudinally and parallel to each other, wherein the selvage edge overlaps the other membrane.
In preparing the first preferred embodiment of the present invention, the top layer is extruded onto a calendaring roll and is concurrently laminated to the middle layer. Then the bottom bituminous layer is manufactured separately and laminated to the middle layer through calendaring rolls. The composite so-obtained is rolled up, preferably, with a release film so that the bottom layer does not stain the top layer. The rolled up product is packaged ready for shipment to the site of installation.
Applications of the finished product onto a roof deck may be accomplished by the following methods: cold applied adhesives, hot mop application of asphalt, torch application, and flood coat application.
In the drawings, like numerals denote like parts/components.
The invention hereinafter described is in reference to two preferred embodiments. In one preferred embodiment the composite roofing membrane comprises: a top layer of thermoplastic polymer; a middle layer of a fleece material; and a bottom layer of a modified bitumen composite. In another preferred embodiment the composite roofing membrane comprises: a top layer of thermoplastic resin reinforced by a polymeric scrim or sheet; a middle layer of a fleece material; and a bottom layer of modified bitumen composite reinforced by a polymeric scrim or sheet.
The middle layer 14 is of a fleece material of polyethylene or polyester having a thickness of form about 0.05 mm to about 0.5 mm and preferably from about 0.01 to 0.4 mm consisting of soft piles with interstices between the piles wherein the interstices are from about 0.1 mm to about 0.5 mm in diameter to allow wicking of flowable materials therethrough, i.e. the thermoplastic top layer and the bituminous bottom layer in flowable form. In terms of weight, the fleece material is typically of 3.5, 6.0 and 10.0 oz per yd2. The fleece material is not a support scrim or sheet which provide strength to the composite membrane, it is an interlocking layer to facilitate bonding of the thermoplastic top layer to the bituminous bottom layer in order to create a mechanical lock between the top and bottom layers.
The bottom layer 16 is of a modified bitumen composite wherein the modifier is selected from the group consisting of atactic polypropylene (APP), styrene-butadiene-styrene (SBS), styrene-ethylene-butadiene-styrene (SEBS) and styrene-butadiene rubber (SBR). The layer has a thickness of form about 0.5 mm to about 20 mm, and preferably 5 mm to 15 mm.
Bitumen is well known and used in the prior art. The APP can be present in the APP modified bitumen in an amount from 5-30% w/w, preferably 7-15% w/w, and most preferably 12-22% w/w. The APP modified bitumen typically comprises 25-75% w/w bitumen and optionally small amounts of isotactic polypropylene (IPP) to enhance stiffness, fillers, fire retardants, and adjuvants. When used, IPP can be added in amounts of up to 20% w/w, fillers such as mica, talc, aluminum and CaCO3 in amounts of 540% w/w, fire retardants such as aluminum trihydride (ATH), zinc borate and (CaO)2(B2O3)3.5H2O in the amounts of up to 40% w/w.
In practice, the APP modified bitumen and the above-listed additives are compounded at a temperature of from about 300° F. to about 450° F.
If desired, pigments in the amount of 0.1-5% w/w may be compounded with the APP modified bitumen along with the listed additives, such pigments include carbon black, titanium dioxide, chromium oxide, yellow iron oxide, ultramarine blue, red iron oxide, metal ferrites and mixtures thereof.
In order to render the appearances of the composite roof membrane uniformly smooth on top of the roof deck, the composite roof membrane is equipped with a selvage edge having a width of about 2-10 inches, preferably 3-9 inches, and most preferably 4-8 inches. A selvage edge 18 is disposed in the bottom layer 16 along one side of the membrane 10. As the composite membranes are positioned longitudinally and parallel to each other on installation, the selvage edge overlaps and covers the other membrane rendering the roof surface smooth and continuous without bumps.
The composite roofing membrane can be manufactured using techniques and equipment used by the prior art. Typically, the top layer is extruded through a hanger die onto a calendaring roll to which layer the middle layer is concurrently laminated. The bottom layer is separately manufactured then laminated to the middle layer using a calendaring roll. The so-obtained composite membrane is preferably rolled up with a release film so that the bottom bituminous layer does not stain the top layer.
The composite roofing membrane typically has a width ranging from about 3 feet to 4 feet. The selvage edge disposed on the side of the membrane can have a width of about 2-10 inches, preferably 3-9 inches, and most preferably 4-8 inches.
Installation of the composite roofing membrane includes prior art accepted methods such as: cold applied adhesive application of modified and non-modified adhesives; torch application; hot mop application; and flood coat application.
The present invention has been described with particular reference to two preferred embodiments thereof. However, it will be understood that changes and modifications may be made which are within the skill of the art. Such changes and modifications are intended to be covered limited only by the scope of the appended claims.
This application is a continuation of U.S. patent application Ser. No. 10/841,045, filed May 7, 2004.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 10841045 | May 2004 | US |
| Child | 11429082 | May 2006 | US |
