CROSS-REFERENCE TO RELATED APPLICATIONS
FIELD OF THE INVENTION
This application has priority from provisional application No. 60/386,880, filed Jun. 6, 2002.
The present invention concerns a composite material with a synthetic fiber structure on the top surface laminated to a plastic film to provide protection to a membrane roofing system used primarily on commercial and industrial roofs but also in residential roof applications and as a walkway on some trucks, cars and storage houses (all referred to as “roof” or “roofs” herein). The fibers may be protected from ultraviolet-exposure induced degradation and chemical degradation and may contain fibers to provide antimicrobial and antifungal protection. The plastic films are chemically compatible with the various membrane systems.
Historically, commercial and industrial roofs have been covered with Bitumen (“tar”) and gravel. While these worked well for many years, they either degraded from sun and weather or suffered from leaks caused by people walking on the roof creating punctures in the surface by driving the stones into the bitumen or by dropping tools or parts onto the roof.
Almost all commercial and industrial roofs, and the like, have auxiliary equipment such as air conditioning units, skylights, roof drains, etc. that need to be serviced regularly. Tradepersons walk regularly across the roof surface creating wear. Installation and maintenance of the auxiliary equipment per se can cause leaks in the roof.
As environmental awareness increased, the runoff of storm water from these bitumen roofs has been found to contaminate ground water.
Synthetic membrane films have been developed to provide a completed sealed film over the entire roof. These films can be seamed using heat, solvents, vibration, or ultrasonic welding, and adhesives. The films can be fastened to the underlying roof deck or can be ballasted with washed river rock to keep them in place during heavy winds and weather.
However, the vulnerability of these roofs is still puncture or abrasion from tradespersons working on the roof and/or from the auxiliary equipment per se.
For rough service areas, some products are used that laminate a fiberglass or synthetic woven or non-woven fabric to the underside of the membrane for increased strength. However, the film is still vulnerable to puncture and abrasion.
- SUMMARY OF THE INVENTION
It is the object of the invention to provide a system solving the above problems.
BRIEF DESCRIPTION OF THE DRAWING
The present invention solves the problems associated with the prior art by providing a non-woven fabric laminated to a film that becomes a relatively narrow wear surface (walkway) covering the traffic area. The non-woven fabric is structured to provide for resistance to ultra-violet degradation, resistance to chemicals (as required), and excellent abrasion resistance. While woven, knitted, or tufted fabrics can be used within the scope of this invention, a non-woven fabric is superior because it will not fray or unravel, especially at the edges.
FIG. 1 is a cross-section of a laminate in accordance with a preferred embodiment of the invention; and
FIG. 2 is an isometric view of a roof-top with such a walkway installed.
- DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
The film can be of any of the synthetic polymers used in the roofing industry, such as: PVC, EPDM, Polyethylene, polypropylene, TPO, EVA, etc. The film can be directly extruded and directly calendered, or attached with an adhesive. The thickness ranges from 0.005″ to 0.120″ (0.1 to 3.0 mm). The width of the film/fabric can be adjusted from 6″ to 16 feet to provide protection to the desired area. The film/fabric can be either laminated on top of the film covering the entire roof or it can be spliced in to the films covering the roof to make a continuous film.
As shown in FIG. 1 the roof R comprises a deck member D seated on I-beams IB or other roof supporting interior structure with insulation provided optionally, as indicated at INS-1. The decking which can be a plate, of corrugated form or combination is overlaid with a roof covering system comprising a rubbery membrane M overlaying further insulation INS-2 which can be tapered or provided with intermittent tapered ribs to establish a drainage pitch for the roof. The walkway material O has a lower plastic film 12 and overlying (upper) non-woven fabric layer 14 adhered thereto and the walkway material 10 is bonded to the membrane M covering by self bonding through heating, pressure and/or high frequency impact and/or through adhesive and/or mechanical fasteners or holders. FIG. 2 shows a portion of roof R with wall or curb C, an access kiosk K (with door D) covering a stairway or ladder and a unit to be serviced or replaced intermittently such as a condenser, HVAC. The walkway 10 has a first section 10-1 meeting a second section 10-2 at a Tee intersection and a border 10-3 e for walking around HVAC. The walkway will normally be retrofitted to an installed membrane roofing system permanently installed but can also be made as original equipment manufacture (OEM), i.e. pre laminated to the membrane covering layer prior to installation on a roof.
The non-woven fabric can be of a wide variety of constructions including needlepunch, spunlaced, spunbonded, or chemically bonded. Generally, natural or cellulosic fibers are unsuitable. The fibers can be made of most synthetic polymers, but the best ones are: Polyester, Polypropylene, PTT, 3GT, PCT, Nylon, and Polyethylene. These can be enhanced with pigmentation and/or UV stabilizer and fire retardant to improve their properties. The fibers should be in the range of 1.5 to 110 deniers (1.7 to 120 dTex) with a length of 1″ to 8″ (25 to 200 mm), but could be made from continuous filament tow. Pigmented polyester fibers appear preferable and can be acceptable even without UV stabilizers (except for extreme UV exposures, e.g., in U.S. Southern states). Another factor of selection is melt temperature (polyester being preferred and polyethylene and polypropylene being marginal) when the fibers are to be heat treated within the non-woven fabric or adhered to the film by heating.
Various fiber properties were studied. It was determined that there are several possible variants depending on applications:
Denier: Fibers from 1.5 to 5.5 deniers were studied and found to be poor for abrasion resistance and resilience. Fibers from 6 denier to 30 denier were found to be the best. Fibers over 30 denier were found to be too coarse to get good coverage at reasonable weights. Blends of deniers were found to offer good coverage with excellent wear properties. Foe example, a blend of 40% 6 denier, 40% 15 denier, and 20% of 40 denier provided an excellent wear surface.
Staple Length: Shorter fibers were found to have less durability. Fibers less than 2″ did not provide adequate strength. the best properties occurred with fiber lengths between 2″ and 6″.
Tenacity and Elongation: These properties did not appear to make a significant difference in wear properties. However, it is well known that low tenacity fibers (less than 3.5 grams/denier) create fibers with low pilling characteristics. The pills actually break off and the appearance remains better if pilling occurs. However, the best results were obtained by controlling the structure, particularly a random velour non-woven.
Texture: Various non-woven textures were reviewed. The best performance came from a random velour non-woven. The low pile height provided the best resilience and was the easiest to clean. It was found to be cleaned easily with hose and water. Other products such as structured non-wovens using rib, chevron, and other patterns were found to be very durable but harder to clean and remove debris. Tufted carpets were tested and were found to be fairly durable, but not readily available with UV stabilized fibers. The cut pile types were easier to clean than the loop types, which tended to snag debris.
Film Polymer Types: All types of standard film including PVC, EPDM, TPO, CSPE, and modified bitumen were reviewed. The fabric can be laminated to the film during normal extrusion or calendering of the film. The fabric can also have an extruded backing film of a low melt point thermoplastic such as PE or EVA which can be heated and used as an adhesive to the above listed films. This way the fabric can be applied over existing film roofs in the area needed. An electric heat gun was used with excellent results as was a propane wide flame torch. The choice of polyester as a face fabric gave greater tolerance to heat.
Antimicrobial Properties: Fibers: Fibers with antimicrobial additives can be blended in with the face fibers. Fosshield® core/sheath bi-component polyester fibers were blended at 10-25% with untreated polyester fibers. 15% was found to be adequate to prevent the formation of mold and mildew around cooling towers, especially in the shade.
The composite material can utilize flat or textured or rippled films (e.g. corrugated in length or width directions). It can have films with spacers such as ribs, ball or point (conical or cylindrical or other shapes of) extensions. The fibrous and film elements of the composite can be bonded in extrusion or calendaring equipment, or scanning with a radiant heater for self-bonding or via adhesives or cold methods such as ultrasonic welding. The laminate as a whole can be bonded to existing membrane (or tar) roofing material by ultrasonic welding, adhesives or heat scanning to overlay the roof in whole or in parts such as patches, walkways or service or play areas.
Preferably the laminate is provided with margins of the film free of overlying fabric for bonding with margins of adjacent such laminates directly ore via an intermediate ribbon or sheet.