"ROOF OVERLAY MADE OF RECYCLED ASPHALT SHINGLES" Technical Field The present invention is concerned with a novel material made of recycled bitumen-derived products such as asphalt shingles. The material comprises, in addition to the recycled shingles, at least one polymer to improve its flexibility and malleability. The material is moulded into a sheet that can be easily bent to follow the surface of supporting material, such as for example a roofing structure.

Background Art Various perlite boards are known to have different end uses, for example, as a fire-resistant insulation board to be laid directly on a steel roof deck, followed by a BUR system. This product has an inorganic perlite content of 70 percent, and accordingly, there is not much hygroscopic cel- lulose fiber present in such board. To produce large two-by-four-foot boards, extra cellulose fiber and starch binder are necessary and, as a result, the perlite content is necessarily reduced.

Subsequently, it has been found that the application of hot BURz or MBw directly over isoboards results frequently in blistering. To overcome this problem, it has been recommended that isoboards be overlaid with a thin layer of a glass fiber board, a wood fiber board or a perlite board.

Consequently, a thinner and stronger board acting solely as an overlay was obtained. Such overlay can be 1/2-inch"recover board,"a product already in the marketplace as an overlay for existing roofing; or something specifically designed as a blister-protection board to overlay isoboards. However, such overlay still blisters when hot-mopped to isoboards. The phenomenon that causes blistering and a test that enables

researchers to find suitable products are still unknown. In other words, there is still a great need to develop a blister-free overlay sheet or board.

Waste landfills are reaching a crisis level, and as a result, waste management has become even more challenging. Current legislation has rendered the handling and processing of wastes significantly more difficult and costly for industries. As production increases, so does the waste. The need for special departments to handle and dispose of such waste has now become a serious problem affecting space, personnel, transportation and landfill. Unknown to the consumer, these waste disposal costs are ultimately built right into the industry's consumer price.

It is well known that during the manufacture of conventional polymer-modified asphalt blends, additives such as styrene-butadiene- styrene (SBS) block copolymers are introduced, to eventually produce modified bituminous compositions. However, during the blending of SBS polymers with bitumen, certain conditions of temperature, time and mixing must be avoided. Excess time and temperature can result in significant thermal degradation of the polymer, thus significantly impacting on both the physical and performance properties of the composition.

Styrene-butadiene-styrene block (SBS) copolymers were introduced as modifiers to improve the properties of bitumen in the early 1970s.'Since that time, a significant amount of research has been completed both on a laboratory scale and in some specific larger scale equipment. To date, however, this information has not been compiled to determine the effect of the total mixing process used in the preparation of SBS-modified bitumen compositions from which sheets or boards are produced.

Disclosure of the Invention It is an aim of the present invention to provide a useful composition made from recycled bitumen-containing products.

A composition in accordance with the present invention is suitable for the manufacture of a sheet of board useful in the building industry, comprising a waste bitumen-containing product, and at least one polymer in an amount sufficient to provide a flexibility and malleability sufficient to allow a workman to bend the membrane upon installation onto the surface of a supporting material or receiving surface.

Brief Description of the Drawings FIGURE 1 shows a perspective view of bonding of the asphalt membrane onto a styrofoam substrate; FIGURE 2 shows a perspective view of several sheets of asphalt membrane overlaid on an assembled substrate; and FIGURE 3 shows a cross section of an asphalt membrane moulded over an edging parapet.

Mode for Carrying Out the Invention The present invention is directed to the recycling of asphalt roof shingles into a novel composition with polymers, that can be cast into sheets or boards suitable for use as a roof overlay or as a waterproofing material in the building industry, including the construction of bridges and podium decks, vertical walls, roofs, and parking garages. Such overlay has excellent physical properties coupled with ease of compounding at low temperatures, i. e., lower than 100°C. This permits simplified moulding of sections of the sheets or boards to the applicable substrate structure, following the application of localized heat. The overlay according to the invention may be produced in various sizes, thickness and lengths depending on the intended use. Anyone of ordinary skill in the art will easily come to the appropriate combination of these parameters to comply with the required specifications. Typically, the overlay comprises a width of up to 4 feet, preferably between 1 and 3 feet; a length varying from 1 to 10 feet, preferably between 2 and 8; and a thickness of at least 1/16 inch.

Preferred polymers for increasing the flexibility and permeability comprises ethylene vinyl acetate, polypropylene, polyethylene, polyethylene glycol, chlorosulphonated polyethylene such as Hypalon", and the like, as well as mixtures thereof. The composition also preferably comprises one or more stabilizers such as thioether or a phenolic derivative like Irganox". A most preferred composition according to the invention would comprise the following: -60 to 80 % by weight of waste shingles ; -20 to 30 % by weight of ethylene vinyl acetate ; -2 to 10 % by weight of chlorosulphonated polyethylene ; -0. 5 to 3 % by weight of polyethylene glycol ; and -0. 05 to 0. 2 % by weight of a phenolic stabilizer.

The asphalt membrane or overlay according to the present invention has several important advantages. It has so far shown superior strength to traditional fibre boards. The overlay is a waterproof material which substantially eliminates all blistering, material separation and air pocket problems. Because the overlay comprises asphalt, conventional hot-mop tar bonds directly thereto to form an integral surface. Due to its improved elasticity resulting from the addition of various additives, the overlay can be moulded onto any surface for a variety of uses. For example, laminated directly onto insulation or styroform as in FIGURE 1, with a shiplapped outer edge to improve joint integrity as in FIGURE 2, or moulded to form ridge caps, gutters, gutter cappings, flashings, starter sheets, etc.

Figure 3 shows an asphalt sheet moulded over a roof edge parapet.

Another important advantage of this material is that it can be pelletized for easy shipment. Finally, because of the source of starting material is cheap, resulting from waste roofing debris from flat or shingled roof replacement, shingles formed of cellulose felt or fibreglass mat, as well as waste generated from the manufacture of these products, the overlay will easily compete in terms of its sale price with other current products sold for the same purpose. The present overlay however, also comprises significant

advantages over these competing products, such as the absence of blistering and ease of application on site.

The composition of shingles may vary greatly from one source to the other. The present invention has been developed to allow the use of any and all waste shingles produced currently. Typical compositions of shingles include bitumen with 100-dmm penetration asphalt flux; a linear SBS block copolymer comprising a styrene-butadiene ratio of 31 to 69; the remaining being calcium carbonate as a filler.

Several samples of the present composition have been moulded a first time into an overlay, and subsequently remixed in a Banbury"and moulded again without any problem, thereby confirming recyclability of overlays obtained therewith. Several physical properties on 5 overlay samples were tested in thickness varying from 1/16 to 3/4 inch. The results are as follows: -after 24 hours at 23C, the samples were bent at 90 on one side, and bending was repeated on the other side. None of the samples tested broke; -none of the samples tested showed water absorption after a 24 hours immersion at 23C.

Referring to FIGURE 1, in a possible method of application of the asphalt membrane overlay 10 onto a flat styrofoam underlay surface 12, a generous spraying of a specialized two-part polyurethane adhesive blend 14 is applied to the contacting surface area 16 of the styrofoam 12, and the sheet of asphalt membrane 10 is placed overtop, such that the contacting underside 18 of the asphalt membrane 10 completely covers the required exposed styrofoam surface 16. This joins by fast bonding the asphalt membrane 10 to the underlying styrofoam 12. This laminated section 20 can be used by itself, or in combination with other such laminated sections, depending on the application and location of use.

FIGURE 2 depicts an assembly 22 of several individual laminated sections 20 of the asphalt membrane 10 and the styrofoam underlay 12 as

described above and shown in FIGURE 1. For covering a large surface such as a roof for example, sections of styrofoam underlay 12 can be laterally fastened together using the polyurethane adhesive blend 14 to bond their vertical edge faces 24 together. In a similar manner as described above for laminating a single section 20, the sheets of asphalt membrane 10 can be overlaid and bonded to the underlying styrofoam surface 12 using the polyurethane adhesive blend 14. Flush abutting joints 26 between the overlying asphalt membranes 10, are ensured by overlapping the top edges 28 of the underlying styrofoam surface sections 12 with the lateral edges 30 of the asphalt membrane 10. This ensures flush abutting joints 26 of the asphalt membrane 10, creating a large waterproof asphalt membrane surface 36. A flashing 32, which can equally be a thin strip of asphalt membrane moulded to fit, can be used to join the asphalt surface 36 to a roof edging parapet 34. This allows for easy bonding of the flashing 32 to the flat roofing asphalt membrane surface 36.

Referring now to FIGURE 3, in which a cross section of a roof surface 33, overlaid with a laminated section 20 of a styrofoam surface 12 and asphalt membrane overlay 10, and an edging parapet 34 is shown. A light gage asphalt membrane 38 to be secured to a non-flat substructure such as a roof edge parapet 34, is similarly bonded to the substrate surface using a generous amount of the polyurethane adhesive blend 14, but is moulded to the shape of the substructure 34 by applying open torch heat directly to the surface area requiring forming. This causes a softening of the asphalt membrane 40, allowing a tight moulded fit over the substructure 34.

While the invention has been described in connection with specific embodiments thereof, it will be understood that it is capable of further modifications, and this application is intended to cover any variations, uses or adaptations of the invention following, in general, the principles of the invention, and including such departures from the present description as come within known or customary practice within the art to which the invention pertains, and as may be applied to the essential features hereinbefore set forth, and as follows in the scope of the appended claims.