Abstract:
A roofing laminate includes a roofing membrane, preferably a white roofing membrane, which is covered with a protective sheet. The protective sheet is tinted so that it has a coloration distinguishable from the roofing. The roofing laminate is applied to a roof surface and the release liner protects the outer surface of the membrane from scrapes and dirt during installation. Once the roof is installed the protective sheets are removed from all of the membrane sheets, exposing a clean surface.

Description:
BACKGROUND OF THE INVENTION 
     Membrane roofs are roofs that are covered with a polymeric sheet or membrane. These polymeric sheets can be, for example, polyvinyl chloride (PVC), thermoplastic olefin (TPO), or ethylene propylene diene monomer rubber (EPDM), as well as many others. The polymeric sheet is positioned over a roof surface and held in place by fasteners, adhesive, or ballast. Adjacent sheets are bonded together along lap seams to form a unitary single sheet of the polymer covering the entire roof. 
     Generally, the roofing membrane is either white or black. Theoretically, the membranes could be basically any color. 
     One chooses a white membrane roof for either aesthetic purposes or to reduce energy costs by reflecting thermal energy. In either event, it is important that the white membrane roof sheeting be clean, i.e., white, subsequent to installation or it will not provide the aesthetic appearance desired nor have the same reflective properties. 
     Particularly, when replacing an existing roof, it is difficult to keep the new sheeting clean. In a re-roofing application, a section of the old roof covering is removed and new roof membrane is immediately installed in its place. This allows the roof to be fully covered each night. As subsequent sections of the old roof are removed, the roofers walk on the previously installed new membrane. This can scratch and mar the new membrane. Even when installing a new roof, it is difficult to keep the white membrane clean during installation. 
     SUMMARY OF THE INVENTION 
     The present invention is premised on the realization that during installation of a single-ply roofing membrane, the surface of the membrane can be protected from dirt, scratches and scrapes by providing a removable tinted or colored release liner adhered to the membrane. The release liner is left in place during installation of the white membrane roof sheeting and be removed after completion of the installation. The tinting or coloration on the release liner ensures that the release sheet is noticeable and not inadvertently left on the roof. Further, the release liner can be formed from an environmentally degradable polymer so that even if some portions of the release sheet remain on the roof, they will degrade quickly and basically wash off the roof. 
     The objects and advantages of the present invention will be further appreciated in light of the following detailed description and drawings in which: 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         FIG. 1  is a perspective view of the present invention; 
         FIG. 2  is a cross sectional view taken at lines  2 - 2  of  FIG. 1 ; 
         FIG. 3  is a cross sectional view of an alternate embodiment of the present invention; 
         FIG. 4  is a perspective view of the present invention during installation; 
         FIG. 5  is a cross sectional view of an edge portion of the present invention during installation and prior to removal of the release sheet. 
         FIG. 6  is a perspective view of an alternate embodiment of the present invention; 
         FIG. 7  is a cross sectional view broken away taken at line  7 - 7  of  FIG. 6 . 
         FIG. 8  is a cross sectional view partially broken away of a second alternate embodiment of the present invention; 
         FIG. 9  is a perspective view of a third alternate embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     The present invention is a roof laminate  10  that includes a roof membrane  12  and a release sheet or protective sheet  14 . The roof membrane  10  includes a first surface  16  and a second surface  18 , and, likewise, the release sheet  14  includes a first surface  20  and a second surface  22  which rests on and covers the first surface  16  of membrane  12 . 
     Membrane  12  can be formed from any polymer typically used in roofing applications. These include polyvinyl chloride, thermoplastic olefin, ethylene propylene diene monomer rubber polyethylene polyolefin, as well as others. The membrane can have a bottom fibrous surface referred to as fleeceback, which improves bond strength in a fully adhered system. The membrane  12  is preferably white or slightly off-white. It can be any color. The present invention is most useful when the membrane is a lighter color, such as white or off-white, and is least advantageous when the membrane is black. Although theoretically one may want to incorporate a protective covering over a black sheeting for use in the present invention. 
     Membrane  12  can be any typical size. These can be as narrow as 5 feet and as wide as 40 feet. Length can be 50-100 feet or more. Membrane  12  has a thickness effective for use in a membrane roof system. Generally, these will be 20 to about 160 mils thick. Roofing membranes are water insoluble and designed to withstand environmental conditions for at least 15 to 20 years. 
     The protective sheet  14  is a thin polymeric sheet which can be formed from a variety of different polymers. Although the protective sheet can be clear, it is preferable that it be tinted with a color that is distinguishable from the color of the membrane  12 . Thus, if the membrane  12  is white, the protective sheet  14  is preferably any color other than clear or white, such as green, red blue or yellow. 
     Preferably, the protective sheet  14  is formed from an environmentally degradable polymer. Exemplary environmentally degradable polymers include polyhydroxyalkanoates such as those disclosed in U.S. Pat. No. 5,070,122, polylactic acid and copolymers of polylactic acid and ethylene carbonmonoxide copolymers as disclosed in U.S. Pat. No. 5,135,966. These polymers break down over a period of time, preferably less than a month when exposed to certain environmental conditions, such as sunlight, heat or moisture, or a combination of any of these. Preferably, these environmentally degradable membranes will break down in a matter of days. 
     The roofing laminate  10  is formed by separately forming the roofing membrane  12  and the protective sheet  14 , and laminating the two together. If the protective sheet  14  includes an adhesive layer, this can be formed by co-extruding a pressure sensitive adhesive along with the membrane, or subsequently coating the formed membrane with a pressure sensitive adhesive, in particular a thermoplastic pressure sensitive adhesive. The protective sheet can also be made naturally adherent to the membrane by incorporating tackifiers into the protective sheet and applying the protective sheet to the membrane in a slightly stretched condition which liberates tackifier. The exposed tackifier provides weak adhesion of the protective sheet to the membrane. Once the protective sheet  14  is laminated to the membrane, the laminate  10  is formed into a roll  24 . 
     Alternately, as shown in  FIG. 3 , a thin layer of adhesive  25  may be applied between the first surface of the membrane  12  and second surface of the protective sheet  14  to adhere the two together. The adhesive should be clear and have a preferable adherence to the protective sheet  14  as opposed to the membrane  12 . A water soluble adhesive is preferred so that if any remains on the membrane  12  after removing the protective sheet it will wash away. 
     To apply the membrane  12  over a roof surface  30 , two adjacent sheets  32  and  34  of the roofing laminate  10  are laid down side by side over the roof surface  30 . The membrane  12  of laminate  32  is fixed to the roof, generally using adhesives (not shown). However, other methods such as mechanically fastening the membrane to the roof can be employed. Second sheet  34  of roofing laminate  10  is rolled out and adhered to the roof surface adjacent the first sheet  32  with edge  36  of the second sheet  34  overlapping edge  38  of the first sheet  32 . The overlapping edges  36  and  38  are adhered or welded to each other. 
     With the embodiment shown in  FIG. 1 , the edge portion  40  of the protective sheet  14  on the first laminate  32  is pulled up enough to allow the edge  36  of the second membrane sheet to overlap the exposed edge  38  of the first membrane  32 . The two edges  36  and  38  are then bonded together by heat or adhesive. As shown in  FIG. 5 , the edge portion  40  of the protective sheet from the first laminate sheet  32  is then folded back and rests over the overlapped portion  42  of the two membranes  12 , 12 . 
     As shown in  FIG. 1 , the protective sheet  14  covers the entire membrane  12  from side to side. However, as shown in  FIG. 8 , the protective sheet  14  may cover the entire membrane except for 4- to 12-inch portions on either edges  26  and  28  of the laminate  10 . 
     Alternately, as shown in  FIG. 9 , the protective sheet  14  can include perforations  50 , 52  along side edges  26  and  28 , which allow strips  54  and  56  to be removed from the sheet leaving the field portion  56  of the protective sheet protecting the membrane. Either of these embodiments allow adjacent sheets of membrane to be bonded together while either the field portion, as in  FIG. 9 , or the entire sheet, as in  FIG. 8 , remain on the membrane  12 . 
     Once the roof is fully installed, all of the protective sheets are pulled away from the membrane leaving an exposed white or colored membrane surface free of scratches and dirt. In the event a protective sheet or a portion of a protective sheet is inadvertently left on the roof, sunlight and water will cause it to disintegrate and wash away. 
     An alternate embodiment of the present invention is shown in  FIG. 6  wherein two protective sheets  20 A and  20 B protect the membrane  12 . Sheets  20 A and  20 B overlap in the central portion of the membrane. The overlapped portion  58  lies loose on the membrane  12 . The loose overlapped portions  58  can be easily pulled up, allowing one to remove both protective sheets  20 A and  20 B. 
     This has been a description of the present invention along with the preferred method of practicing the present invention. However, the invention itself should only be defined by the appended claims,