Stock material or miscellaneous articles – Layer or component removable to expose adhesive
Reexamination Certificate
2002-04-25
2004-02-24
Ahmad, Nasser (Department: 1772)
Stock material or miscellaneous articles
Layer or component removable to expose adhesive
C052S177000, C052S181000, C428S040200, C428S040300, C428S041300, C428S041500, C428S141000, C428S143000, C428S147000, C428S354000, C428S356000
Reexamination Certificate
active
06696125
ABSTRACT:
BACKGROUND AND SUMMARY OF THE INVENTION
This invention relates to bituminous roofing adapted for the waterproofing and sealing of substrate structures and to the method of manufacturing such materials. More particularly, the present invention is in the field of roofing membranes and shingles, having a factory-applied self-adhesive layer on the bottom surface and a thermoplastic modifier such as atactic polypropylene modified bituminous compound on the top surface in order to provide easy and hassle-free field application by roofing personnel.
It is well known to use bituminous compositions for manufacturing waterproofing membranes, generally for roof covering and roofing underlayments. Modified bituminous prepared roofing, also referred to as modified asphalt roofing membrane, is typically manufactured using, as a core, a reinforcement carrier support sheet made of fabric such as polyester, fiberglass, or a combination of both, saturating and coating the front and back sides of the carrier with a modified bituminous coating material based on Atactic Polypropylene (APP), Amorphous Poly Alpha Olefin (APAO), Thermoplastic Polyolefin (TPO), Styrene-Butadiene-Styrene (SBS), Styrene-Ethylene-Butadiene-Styrene (SEBS), synthetic rubber or other asphaltic modifiers, that will enhance the properties of asphalt.
Roofing membranes are used in commercial, industrial and residential applications. Two major classifications of modified bitumen roofing materials, which are used mostly in industrial and commercial applications are (1) cap sheet and (2) base sheet. Shingle roofing materials, however, are used primarily in residential applications, and are exposed to the elements, and hence can be considered as ‘cap’ as well. A cap sheet or shingle membrane can be modified using Atactic Polypropylene (APP), Amorphous Poly Alpha Olefin (APAO), Thermoplastic Polyolefin (TPO), Styrene-Butadiene-Styrene (SBS), Styrene-Ethylene-Butadiene-Styrene (SEBS), synthetic rubber or other asphaltic modifiers, and is generally reinforced with a polyester carrier or a combination of polyester and fiberglass. These sheets can be smooth or granular surfaced and are typically greater than 2.8 mm in thickness. The top surface of the cap sheet is exposed to the elements and hence the name “cap”. A base sheet is typically modified using any of the same modifiers as a cap sheet, but due to economic considerations, is modified using smaller quantities of less expensive polymers such as Atactic Polypropylene (APP) or Styrene-Butadiene-Styrene (SBS). A base sheet is generally reinforced with a fiberglass carrier (which costs significantly lower than polyester) and is smooth surfaced. The thickness of such base sheet typically ranges from 1.0 mm to 2.5 mm depending upon the job specifications. In a typical field installation, a base sheet is first applied to the roof deck using mechanical fasteners, via hot mopping or using cold application techniques. Cap sheets or shingles are applied on top of the base sheets, with the seams of adjacent rolls in offset relation. Most APP-modified bitumen membranes are torch-applied, i.e., by heating the back side of the sheet to melt the compound and using the molten compound to form a heat weld. Most SBS-modified bitumen membranes are set during in-field application in hot mopping asphalt, torch-applied or adhered with cold-process adhesives, as described in U.S. Pat. No. 5,807,911 issued to Wentz, et al., on Sep. 1, 1992. Modified bitumen membranes which do not have factory-applied granule or foil surfacing need some form of field-applied ultraviolet protective coating.
Of the two general types of bituminous sheet materials used for roofing applications, i.e., bitumen-SBS and bitumen-APP materials, the bitumen-SBS products are more elastic, with greater flexibility at low temperatures. APP-based products, however, are more heat-resistant (due to a higher softening point), are more resistant against the effects of the atmosphere (especially ultra-violet rays) and more resistant to foot traffic
The manufacture of bituminous roofing material with multiple layers is well-known. For example, U.S. Pat. Nos. 2,893,889; 4,755,409; 4,871,605; and EP Patent No. 903435 disclose membranes comprised of a core and a plurality of different layers of waterproofing material. The '409 patent also discloses a release sheet applied to the one side of the membrane for purposes of protection. Products are in the market which combine the more flexible and elastic bitumen-SBS upper layer with a self-adhesive lower surface. An example of such a product is Plura AD self-adhesive sold by Pluvitec S.p.A., described on the website of the seller at http://www.pluvitec.com. Application of a primer is recommended when using this material in order to ensure adherence of the self-adhesive layer to a substrate, and the use of added heat, i.e., by a torch, is also recommended.
Sheets which are sold as membranes in roll form may be cut into smaller sections to form shingles for use on roofs with greater slope. Shingles are typically nailed into place, and are most commonly used in residential roofing.
Another category of roofing membranes are “underlayments”, which are widely used in residential applications, and may also be designed for use in regions with colder climates, where ice-dam protection is required. Underlayments, commonly utilized under shingle roofing material, metal roofing panels or tile roofing, provide waterproofing characteristics and are typically reinforced with fiberglass. However, there are a few products in the market place that have no carrier such that these consist of simply a coating of self-adhesive compound on a polyolefinic film. Underlayments are typically used in steep slope roofing applications and, therefore, must provide good traction for the safety of the roofer installing the material. A typical underlayment installation involves mechanically fastening the same to the plywood substrate or adhering the underlayment to the plywood substrate using an adhesive compound.
Most underlayment materials designed to be used under metal roofing are based on SBS. Upon installation of such underlayment, metallic panels may be mechanically fastened to the top of the roofing underlayment. It is essential to note that metal generates excess heat and therefore necessitates the use of an underlayment that can withstand high temperature. Also granular surfaced products, whether APP or SBS based, are not recommended since the mineral surface can cause abrasion on the metal. This poses severe problems for the installer of such roofing underlayments in that these products are generally modified with styrene-butadiene-styrene (SBS) compound, which is soft and flows at temperatures above 110 degrees Celsius. Hence it is necessary to develop a product that has high heat resistance and a non-abrasive surface on the exposed side.
Upon installation of the underlayment, in the case of tile roofing, corresponding tiles that may be made of clay or concrete, are loaded to the top of the roofing underlayment. This poses several problems for the installer of the roof in that underlayments are generally thin (less than 2 mm in thickness), smooth surfaced, modified with SBS compound which is soft, and are reinforced with a fiberglass sheet that imparts very poor tear resistance properties to the membrane. Especially when the slope of the roof, commonly referred to as roof pitch, is steep, tiles that are stacked on top of the roof and can weigh from 80 to 100 lbs. per square foot of area, depending upon the type of tiles and the height of stacking, begin to slide down the roof and eventually fall on the ground. Obviously this poses a great risk to people working on the roof and in the vicinity of the same, in addition to damage caused to the underlayment material, and lost installation time.
Consequently, there is a need for a material that is very easy to install as well as durable enough to offer high temperature resistance and resistance to tile slippage.
One object of the present invention is to provide a sheet
Mohseen Shaik
Zanchetta Natalino
Ahmad Nasser
Baker & McKenzie
Polyglass, U.S.A.
Roche David I.
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