Abstract:
A roofing material and process for making same has a granular surface formed from coated granules embedded in an upper layer of modified asphalt. The granules are coated with a coloring composition and with a hydrophobic material. To assure adequate color intensity and a physically strong attachment of the coating on the granule, multiple layers of coloring composition are applied to the granules and are fired at a high temperature for a significant period of time. High reflectivity can be achieved using the coated granules, as well as a high degree of hydrophobicity to aid in shedding water, in particular acidic rainwater to increase roofing membrane performance and useful life.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to roofing materials and more particularly to bituminous roofing materials having granules, such as crushed stone, embedded in an upper side thereof. 
       BACKGROUND OF THE INVENTION 
       [0002]    Bituminous (asphalt) roofing membranes have been known and used for many years for forming waterproof roofs for buildings, both residential and commercial. Most modern bituminous roofing membranes are formed around a fabric sheet made from polyester, fiberglass or the like. The fabric sheet is coated with bitumen (asphalt), that has been modified with one or more modifiers such as Atactic PolyPropylene (APP), Amorphous Poly Alpha Olefin (APAO), Thermoplastic Polyolefin (TPO), Styrene-Butadiene-Styrene (SBS), Styrene-Ethylene-Butadiene-Styrene (SEBS), or synthetic rubber. The modifiers change the properties of the asphalt to increase its utility as a roofing membrane, e.g., to make it more elastic, have greater flexibility at low temperatures and greater heat resistance at high temperatures to prevent softening/flow and deformation from mechanical forces, such as those associated with maintenance personnel walking on the roofing membrane. A roofing membrane may be formed of a laminate of a plurality of types of modified asphalt, e.g., a layer of a first type may be formed on the bottom surface that has an increased adhesive grip on the roofing underlayment and a different layer may be used on the upper surface that has enhanced weather resistance, etc. Adhesive layers may be applied to the membrane to allow the membrane to adhere to a substrate and/or to adhere to an adjacent sheet of roofing membrane. The adhesive may be applied to limited areas, e.g., the edge, where the roofing membrane is intended to overlap. There are a variety of ways for attaching roofing membranes to roofs, such as the application of an adhesive that can be softened by a torch, by “hot mopping” molten asphalt composition to the roof upon which the roofing membrane is applied and adhered, nailing (in the case of shingles) and self-adherent adhesives. 
         [0003]    Bituminous roofing frequently employs an upper surface embedded with granules. These granules impart color, texture, foot/shoe slip-resistance and weather resistance to the roofing membrane. It has been recognized that the color of a roof has a significant impact on the absorbance/reflection of solar energy and therefore has a significant effect on the amount of energy required to heat/cool a building. In hot climates, roofs with greater reflectivity can reduce energy costs related to air conditioning (cooling). In recognition of this effect, government entities have passed laws and regulations pertaining to the color/reflectivity of roofs and established incentives and criteria for selecting roofing materials that result in lowered energy demand. Ratings exist (Energy Star®) to characterize roofing light/heat reflectivity relative to that irradiating a given surface—as a fraction or percentage. 
         [0004]    The reflectivity of a given crushed stone granule surface may be increased by applying a reflective coating to the granule surface of a finished roofing membrane, e.g., by painting the coating on the granular surface. This may be conducted after the roof has been installed on a building, or may be applied to the roofing membrane during manufacture in the factory. If applied on-site, painting a roof is a difficult and laborious process due to roof height, slope and weather conditions and the quality of the finished product is dependent upon the skill and reliability of the workman. A coating applied at the factory also has associated costs and limitations. For example, the coating is applied to heavy and bulky roofing material that typically needs to be dried/cured before the roofing material can be packaged or rolled, significantly complicating the manufacturing process and apparatus needed. In addition, coatings applied to surfaces of roofing material tend to form a relatively fragile layer e.g., where the coating bridges between granules and between granules and the asphalt layer in which they are embedded. In the case of roll roofing, when a coating is applied at the factory and the resultant coated roofing is rolled for storage and transport, the coating can crack, resulting in the degradation of the roofing material. Similarly, bending of pre-coated roofing shingles during installation on a roof can result in cracking the previously applied coating. 
         [0005]    In addition to color/reflectivity limitations of crushed stone used for making granular surfaces of roofing membranes, the granules also have a limited resistance to erosion when subjected to rainwater, and in particular acidic rainwater, which is common in many areas due to air pollution. Acidic rainwater can etch/dissolve roofing granules, diminishing their reflectivity and loosening their embedment within the asphalt layer, such that they may be displaced from the asphalt layer, e.g., when subjected to mechanical forces, such as wind, leaves, snow, rain and the foot traffic of maintenance personnel. In the latter instance, the loosening of granules can result in diminished traction for maintenance personnel. 
         [0006]    Given the limitations of known methods and materials for forming roofing membranes with high reflectivity, durability and weather resistance, improved methods and materials remain desirable, e.g., methods and materials for increasing reflectivity, which are conveniently and safely implemented in the manufacturing setting and preserve roofing membrane flexibility. Furthermore, improvements in roofing materials that make them more resistant to the effects of acid rain remain desirable. 
       SUMMARY OF THE INVENTION 
       [0007]    The limitations of prior art roofing materials are overcome by the present invention which includes a roofing granule having a core with an outer surface. The outer surface of the roofing granule is coated. The independently coated granules can be pressed into an asphalt containing layer to form a granular surface. In accordance with a method of the invention, the coating is applied and cured. In accordance with another embodiment, the coating may be used to impart color and reflectivity to the core and may be applied in multiple layers, each layer being heat cured. In accordance with a further embodiment, the coated granule may be over-coated with a hydrophobic material. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0008]      FIG. 1  is a perspective, partially exploded view of a modified bituminous, laminated roofing membrane in accordance with an exemplary embodiment of the present invention. 
           [0009]      FIG. 2  is an enlarged cross-sectional view of the roofing membrane of  FIG. 1 . 
           [0010]      FIG. 3  is an enlarged cross-sectional view of granules used in the roofing membrane of  FIGS. 1 and 2 . 
           [0011]      FIG. 4  is a diagram of a process in accordance with an exemplary embodiment of the present invention for making and using the granules of  FIG. 3  in a roofing membrane. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0012]      FIG. 1  shows a roofing membrane  10  in accordance with an embodiment of the present invention. The roofing member has an inner sheet or mat  12  composed of polyester or fiberglass or other similar material from which a fabric may be made. Bottom and top layers  14 ,  16 , respectively, of asphalt compound are laminated to opposing sides of the fabric mat  12 . (For ease of visualization, the layers  12 ,  14 ,  16  are shown spaced apart.) The top layer  16  has a plurality of granules  18  disposed over the upper surface thereof forming a granular surface  18   S . Optionally, peripheral edges  20 ,  22  may be left smooth (without granules) to form a substrate for beads of adhesive  24 ,  26 . 
         [0013]      FIG. 2  shows an enlarged cross-section of the roofing membrane  10 , with the layers  12 ,  14  and  16  laminated together. The granules  18  can be seen to be embedded in the upper layer  16  of modified asphalt compound. 
         [0014]      FIG. 3  shows the granules  18  in cross-section and having a plurality of intermediate layers  28 ,  30 ,  32  of coloring composition and an outer hydrophobic layer  34  disposed over a granule core  36 . The intermediate color composition layers  28 ,  30 ,  32  and outer hydrophobic layer  34  depicted are exaggerated in size relative to the granule core  36  for ease of illustration. In fact, color composition layers  28 ,  30 ,  32  are each approximately 1-2 mils thick. The hydrophobic layer  34  is also about 1-2 mils thick. The composition, preparation and properties of these granules is described below.  FIG. 3  depicts a novel aspect of the present invention. More particularly, unlike a roofing system which employs granules embedded in asphalt that are over-coated with a painted-on coating, the granules themselves are independently coated. As shown in  FIG. 3 , there is no coating layer that bridges between granules  18  and the top asphalt layer  16 . As a result, breakage of these absent, fragile and relatively brittle bridge portions of a coating layer is avoided, even if the roofing membrane is bent, e.g., when rolled for storage and shipment. The independently coated granules  18  of the present invention are thus free to move independently as constrained only by the top asphalt layer  16  and by the abutment of adjacent granules  18 . It should be appreciated that  FIG. 3  is diagrammatic as regards to showing a significant spacing between granules  18  (for ease of illustration). In actual roofing membrane  10 , the spacing between granules  18  would be minimal and there would be overlap between granules  18  forming the granular surface  18   S , such that the underlying asphalt layer  16  would be largely obscured from view. 
         [0015]    The outermost hydrophobic layer  34  of the granules  18  aids in shedding water, in particular rainwater, which may be acidic. Besides aiding in one of the basic purposes of roofing membranes  10  (shedding water), the hydrophobic layer  34  also protects the granules  18  from dissolution by rainwater (in particular, acidic rainwater) thereby preserving the color/reflectivity and the dimensions/surface smoothness of the granules  18 . In one embodiment, the hydrophobic layer  34  is clear, such that the coloring composition layers  28 ,  30 ,  32  are visible through the hydrophobic layer  34 . While the hydrophobic layer  34  is diagrammatically depicted as an outer “shell”, it is understood that at the atomic/molecular level level, the composition forming the hydrophobic layer  34  may penetrate into the layers  28 ,  30 ,  32  of color composition and bond therewith. 
         [0016]      FIG. 4  shows a diagram of an exemplary process for forming a roofing membrane  10  in accordance with the present invention. Base granules (for forming the granular core  36  of granules  18 ), such as crushed rock, typically feldspar, basalt, or other types of rock, are mined and processed off site and may be obtained commercially from various quarries and suppliers of crushed stone, worldwide. The base granules (granular cores  36 ) are dispensed  38  into the production line, e.g., onto a conveyer belt or into buckets. The granular cores  36  are then optionally cleaned, dried and graded  40 , e.g., by screening to eliminate granules that are too small or too large (which either pass or do not pass through appropriately sized screens.) and then sprayed with water and/or subjected to air flows to remove small particles of dust and dirt. These processes may be conducted by the supplier of the granules or may be done in-house. A liquid coloring composition to be applied to the granules is prepared  42 . The final color of the granules  18  is determined by the color of the coloring composition (that forms layers  28 ,  30 ,  32 ), rather than the color of the granular core  36 , leading to greater freedom in choosing the type of rock used in forming the granular core  36 , based on its natural coloring. 
         [0017]    An exemplary coloring composition contains the following constituents in the relative weight percentages shown: 
         [0000]    
       
         
               
             
               
               
               
               
             
               
               
               
               
             
           
               
                   
               
               
                 Typical White Coating formulation 
               
             
          
           
               
                   
                 Actual 
                 Range 
                   
               
               
                 Raw Material 
                 WT % 
                 WT % 
                 Description 
               
               
                   
               
             
          
           
               
                 Water 
                 14.09 
                  5-40 
                 Vehicle for thickener 
               
               
                 Ethylene/Propylene Glycol 
                 0.615 
                 0.1-2.0 
                 anti freeze 
               
               
                 Foam Master 
                 0.187 
                 0.1-2.0 
                 defoamer 
               
               
                 Latex Polymer 
                 23.55 
                  7-40 
                 resin 
               
               
                 Natrosol 
                 0.525 
                 0.1-2.0 
                 thickener 
               
               
                 Tamol 850 
                 0.42 
                 0.1-2.0 
                 dispersing agent 
               
               
                 KTPP 
                 0.15 
                 0.1-2.0 
                 dispersing agent 
               
               
                 Titanium dioxide 
                 9 
                  2-15 
                 pigment 
               
               
                 Zinc Oxide 
                 4.5 
                 1-9 
                 anti fungi agent 
               
               
                 Aluminum Trihydrate 
                 9.75 
                  5-30 
                 fire retardent 
               
               
                 Calcium Carbonate 
                 9 
                  2-15 
                 filler 
               
               
                 3.5-12 microns 
               
               
                 Attagel/Minugel 
                 0.54 
                 0.1-5   
                 thickener 
               
               
                 Nuosept 95 
                 0.135 
                 0.1-2.0 
                 preservative 
               
               
                 Foam Master VF 
                 0.188 
                 0.1-2.0 
                 defoamer 
               
               
                 Latex Polymer 
                 23.55 
                  7-40 
                 resin 
               
               
                 Triton 
                 0.195 
                 0.1-2.0 
                 dispersing agent 
               
               
                 Aqua Ammonia 
                 0.105 
                 0.1-2.0 
                 PH modifier 
               
               
                 Texanol 
                 0.735 
                 0.1-2.0 
                 cosolvent 
               
               
                 Skane microbiocide 
                 0.135 
                 0.1-2.0 
                 biocide 
               
               
                 Sanicizer 
                 0.78 
                 0.1-2.0 
                 plastisizer 
               
               
                   
               
             
          
         
       
     
         [0018]    The coloring composition is prepared in accordance with the following exemplary method. 
         [0000]    
       
         
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 WITH MIXER OFF METER IN: 
               
               
                   
                 Water 
               
               
                   
                 TURN MIXER ON AT LOWEST SPEED AND ADD: 
               
               
                   
                 Ethylene/Propylene Glycol 
               
               
                   
                 ADD AND MIX AT LOWEST SPEED: 
               
               
                   
                 Foam Master VF 
               
               
                   
                 TURN OFF MIXER AND ADD BY OUTAGE: 
               
               
                   
                 Latex EC-1791 
               
               
                   
                 * ADD IN ORDER* TURN ON MIXER INCREASE SPEED 
               
               
                   
                 AS NEEDED TO MAINTAIN A VORTEX: 
               
               
                   
                 SLOWLY ADD INTO VORTEX AND MIX 5 MINUTES UNTIL 
               
               
                   
                 LUMP FREE: 
               
               
                   
                 Natrosol 250HR/ER52000 
               
               
                   
                 ADD INTO VORTEX: 
               
               
                   
                 Tamol 681 
               
               
                   
                 ADD INTO VORTEX: 
               
               
                   
                 Tamol 850 
               
               
                   
                 ADD INTO VORTEX: 
               
               
                   
                 KTPP 
               
               
                   
                 **INCREASE MIXER SPEED AND HEIGHT AS NEEDED 
               
               
                   
                 TO MAINTAIN VORTEX: 
               
               
                   
                 ADD INTO VORTEX: 
               
               
                   
                 TI02/CR828/R706/2310 
               
               
                   
                 ADD INTO VORTEX: 
               
               
                   
                 Zinc Oxide/XX503/Azo 66L 
               
               
                   
                 ADD INTO VORTEX: 
               
               
                   
                 Aluminum Trihydrate/C330/DH80/SB432 
               
               
                   
                 ADD INTO VORTEX: 
               
               
                   
                 Calcium Carbonate 3.5-12 microns 
               
               
                   
                 ADD SLOWLY INTO VORTEX: 
               
               
                   
                 Attagel 50/Minugel 400 
               
               
                   
                 ADD INTO VORTEX: 
               
               
                   
                 Nuosept 95 
               
               
                   
                 RINSE MIXER WITH HOSE: 
               
               
                   
                 Water 
               
               
                   
                 ****MIX AT HIGH SPEED FOR 10 MINUTES* MAKE SURE 
               
               
                   
                 TEMPERATURE IS BELOW 120 F. 
               
               
                   
                 ***CHECK GRIND MUST BE 3 MILS OR LESS*** 
               
               
                   
                 ***LET DOWN PHASE*** 
               
               
                   
                 ADD INTO VORTEX: 
               
               
                   
                 FOAM MASTER VF 
               
               
                   
                 TURN OFF MIXER AND ADD BY OUTAGE: 
               
               
                   
                 Latex EC-1791 
               
               
                   
                 ***TURN ON MIXER AND REDUCE SPEED TO REDUCE 
               
               
                   
                 AIR ENTRAINMENT: 
               
               
                   
                 ADD INTO VORTEX: 
               
               
                   
                 Triton X-405 
               
               
                   
                 ADD SLOWLY INTO VORTEX: 
               
               
                   
                 Aqua Ammonia 26% 
               
               
                   
                 ADD SLOWLY INTO VORTEX: 
               
               
                   
                 Texanol/NX795 
               
               
                   
                 ADD SLOWLY INTO VORTEX: 
               
               
                   
                 Skane M8 microbiocide 
               
               
                   
                 ADD INTO VORTEX: 
               
               
                   
                 Sanicizer 160 
               
               
                   
                   
               
               
                   
                 **MIX 5 MINUTES AND HAVE LAB TEST VISCOSITY AND PH** 
               
               
                   
                 ***COVER BATCH WITH 1 GALLON OF WATER USING SPRAY HOSE** 
               
               
                   
                 ***FILTER BATCH DURING PACKAGING*** 
               
             
          
         
       
     
         [0000]    
       
         
               
             
               
               
             
           
               
                   
               
               
                 TEST 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 SOLIDS WT % 
               
               
                   
                 DENSITY LBS/GAL 
               
               
                   
                 BROOKFIELD VISCOSITY 4D/5 rpm/77 F. 
               
               
                   
                 BROOKFIELD KU 77 F. 
               
               
                   
                 WET COLOR-DRAW DOWN 
               
               
                   
                 PH 
               
               
                   
                   
               
             
          
         
       
     
         [0019]    Variations in the foregoing granule coloring composition and method for preparing same may be made, e.g., while the foregoing composition yields a white color, other colors may be obtained by substituting titanium dioxide with another pigment. 
         [0020]    Given a supply of appropriately sized, cleaned and dry granular cores  36 , they are coated  44  with the above-described liquid coloring composition. Coating  44  may preferably be accomplished by dipping the granular cores  36  in the coloring composition, e.g., by passing a perforated conveyor belt or basket supporting the granular cores  36  through a bath of coloring composition. Alternatively, the coating maybe sprayed onto the granular cores  36 . The coated granular cores  36  (hereinafter “coated granules”) are then air dried  46 . Drying may be accelerated by heating, e.g., by passing the coated granules on a conveyor belt through an oven/kiln. The coated granules may be agitated to promote separation of the individual granules (prevent clumping) during drying. In a preferred embodiment of the present invention, the coated granules are fired at a high temperature, e.g., 1300°-1500° Fahrenheit for a significant period of time, e.g., 2 to 24 hours. This assures that the color coating is cured and all solvent has been evaporated. The exemplary liquid coloring composition described above is water-based and therefore no apparatus need be provided to capture evaporated solvent. The granules may be agitated periodically during firing to prevent clumping and/or mechanically separated after firing to promote individuation of the granules. Depending upon the initial color of the granule and the desired end color, multiple coating  44  and drying/firing 46 steps may be performed. For example, given feldspar granules having a reflectivity of 0.28 on the ASTM C1549 solar reflectance scale using a SSR device, three coatings of coloring composition as described above, with a viscosity of 1000-20000 CPS will yield a bright white granule having a reflectivity of 0.74 suitable for producing roofing membrane having an Energy Star® rating of 0.65 to 0.74. Accordingly, at step  48 , it is determined if a sufficient number of coats of the coloring composition have been applied. If not, the coated granules are recoated  44  and dried/fired  46  until a sufficient number of coats have been applied. (Multiple coats also ensure that the granule is coated over substantially the entire outer surface with coloring composition, e.g., to compensate for any bare spots that might result from incompletely coating the granules or due to declumping before or during firing. Acceptable granules should be at least 75% covered over the entirety of their outer surface and preferably 80% to 100% covered to insure high reflectivity. The coated granules are then fired 50 in an oven/kiln at a high temperature for a prolonged period of time, e.g., 1300°-1500° Fahrenheit for 2 to 24 hours.) 
         [0021]    A hydrophobic coating (to be applied as hydrophobic layer  34 ) is prepared  52 , having the following composition: 
         [0000]    
       
         
               
               
               
               
             
               
               
               
               
             
           
               
                   
               
               
                 Water Seal Coating 
                 Actual 
                 Range 
                 Description 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 Water/Medium Aliphatic 
                 70% 
                 50-90%  
                 Solution vehicle 
               
               
                 oil 
               
               
                 Steric Acid 
                 25% 
                 8-35% 
                 protectant for weathering 
               
               
                 Parapol 
                 5% 
                 2-10% 
                 water repellant 
               
               
                   
               
             
          
         
       
     
         [0022]    The hydrophobic coating is prepared by adding and mixing the foregoing in the above-listed order. 
         [0023]    The color coated and fired granules are then coated  54  by spraying or dipping with the hydrophobic coating and dried/fired  56 . As before, the firing may be conducted at high temperatures, e.g., 1300°-1500° Fahrenheit for 2 to 24 hours. This process may be repeated to apply additional coats of hydrophobic coating 34, if desired. The finished granules  18  display a hardness of 5.0 on Mohr&#39;s mineral scale, are non-toxic, hydrophobic, bright white in color and have a reflectivity: 0.74 or 74%. As noted above, the granules are preferably graded/sized prior to coating and may be re-graded after coating. For roofing granules, a suitable granule size is 12-30 mesh. The granules  18  resulting from the foregoing process are then supplied to the processing line  58  and used to prepare roofing membrane  10 . 
         [0024]    A fabric mat  60  is supplied to the processing line  58  from a mat unwinding station  62 . The mat  60  is saturated with modified asphalt in saturation tank  64 , forming a composite mat 60 c . The thickness of the composite mat  60   c  may be controlled by calendar rolls  66 , which also impart smooth, flat upper and lower surfaces to the composite mat  60   c . The composite mat  60   c  may be subjected to various processing steps, such as scraping selected areas for the application of adhesive, the application of release strips to the adhesive, etc., based upon the finished product desired. Coated granules  18  may be supplied to and dispensed by a surfacing applicator  68  onto the hot composite mat  60   c , which is then cooled by a chilled water bath  70  to about 95° Celsius. The granules  18  carried on the upper surface of the composite mat  60   c  are then pressed into the surface thereof by press rollers  72 , such that the granules  18  are embedded in the modified asphalt, which mechanically grips the granules  18 , when fully cooled. The hydrophobic layer  34  on the granule  18  is compatible with the modified asphalt of layer  16  in that both are co-valent in nature, such that the asphalt adheres to the surface of the coated granules  18 . Illustrating one possible roofing membrane embodiment, the bottom side of the composite mat  60   c  can be coated with a self-adhesive layer in coating vat  74 , forming a three part laminate mat  60   L , which is then cooled on a cooling belt  76 . The membrane then passes through an accumulator  78  and then to a winder  80 , where it is cut and wound into rolls of finished roofing membrane. Release films may be inserted to prevent self-adhesive layers from bonding to an opposing surfaces of the roofing membrane when rolled into a roll. Alternatively, the roofing membrane  10  may be provided with a sand backing to prevent transfer of asphalt from the rear surface of the roofing membrane  10  to the upper granulated surface  18   S . 
         [0025]    The foregoing roofing membrane  10  is flexible due to the fact that the granules  18  are each embedded (to about 50% of their extent) in the modified asphalt, but are not joined to adjacent granules  18  by an over-coating which bridges there between, as would be present with a painted-over granulated upper surface  18   S . The independently coated granules  18  have a stable color coating ( 28 ,  30 ,  32 ) which is not prone to cracking or degradation from bending of the roofing material, e.g., when it is rolled into rolls or bent during installation. The upper surface of the roofing membrane is reflective, having an Energy Star® rating of 0.65 to 0.74, due to the coated granules  18 . This high level of reflectivity protects the roofing membrane  10  from sun damage by keeping the roofing membrane cooler, thereby avoiding degradation of the modified asphalt and softening/flow thereof. By preventing softening, the undesirable release of granules  18  from their embedded position in the asphalt  16  is also prevented, increasing the useful life of the roofing membrane  10  and preserving a reliable footing surface for workers who walk on the roof, particularly in sloped roof applications. 
         [0026]    The hydrophobicity of the hydrophobic layer  34  on the granules  18  making up the granular surface  18   S  of the roof membrane  10  aids in shedding water from the roof surface to prevent water infiltration and to reduce the amount of time the roof remains wet, thereby minimizing the growth of moss and other unwanted plant growth. In addition, the shedding of rainwater also reduces the exposure time of the roofing membrane  10 , in particular the granules  18 , from the corrosive effects of acidic rainwater, which could otherwise attack the core  36  of the granule  18 , with negative implications on reflectivity and useful life of the roofing membrane. More particularly, etching of the granule  18  would alter the size/color and/or smoothness of the granules  18 , leading to diminished reflectivity and granule retention. In the case of a granule having a colored coating composition, a hydrophobic coating can also shield the color composition layer(s)  28 ,  30 ,  32  from the effects of acidic rainwater. 
         [0027]    The above-described reflective and hydrophobic granules  18  can be used in combination with a variety of roofing membranes and systems. For example, the granules  18  can be embedded in the surface of the roofing membranes described in U.S. Pat. No. 6,924,015 to Zanchetta et al., entitled, Modified Bitumen Roofing Membrane With Enhanced Sealability and/or U.S. Published Patent Application No. US 2007/0054987 to Zanchetta et al., entitled Polyethylene Modified Asphalt Compositions, each of which are incorporated herein by reference in their entirety. The granules  18  of the present invention can be utilized in conjunction with standard commercial modified asphalt roofing materials, such as APP, SBS hot-mopped, torch or self-adhered roofing membrane, roll roofing and flashing for new roofing, re-roofing, re-covering and BUR (built up roofing) repair applications (as a cap sheet). Roofing membranes  10  in accordance with the present invention may be used on flat roofs (with pedestrian access, or limited access, profiled metal decks, industrial sawtooth roofs and curved roofs. 
         [0028]    While the present invention has been described in reference to specific embodiments thereof those with normal skill in the art may see the possibility of making variations on these embodiments without departing from the scope of the present invention. It is intended that all such variations fall within the scope of the appended claims.