Use of inorganic acids with crosslinking agents in polymer modified asphalts

Abstract

Asphalt and polymer mixtures treated with an inorganic acid and crosslinked with sulfur and/or other crosslinkers or accelerators gives a polymer modified asphalt with improved high temperature properties. The acid should be added to the asphalt before the crosslinker.

1 . A method for preparing asphalt and polymer compositions comprising: 
 heating an asphalt;    adding an elastomeric polymer and an inorganic acid to the asphalt in any order to form a mixture, where the proportion of inorganic acid ranges from about 0.05 to about 2 wt % based on the total mixture;    adding a crosslinker to the mixture after the addition of the acid; and    curing the mixture to give a polymer modified asphalt (PMA).    
     
     
         2 . The method of  claim 1  where the elastomeric polymer is a vinyl aromatic/conjugated diene elastomer.  
     
     
         3 . The method of  claim 2  where the elastomeric polymer is a styrene-butadiene copolymer.  
     
     
         4 . The method of  claim 1  where the inorganic acid is selected from the group consisting of phosphoric acid, polyphosphoric acid, sulfuric acid, hydrochloric acid, nitric acid, and mixtures thereof.  
     
     
         5 . The method of  claim 1  where the proportion of inorganic acid ranges from about 0.05 to about 1 wt % based on the total mixture.  
     
     
         6 . The method of  claim 1  where the crosslinker is selected from the group consisting of sulfur, mercaptobenzothiazole and metal salts thereof, thiurams, dithiocarbamates, sulfur-containing oxazoles, thiazole derivatives, and mixtures thereof.  
     
     
         7 . The method of  claim 1  where the PMA has an improved high temperature property as compared with an identical PMA absent the inorganic acid, where the property is selected from the group consisting of ODSR and RTFO fail temperatures and combinations thereof.  
     
     
         8 . The method of  claim 1  where the elastomeric polymer comprises from about 1 to about 20 wt % of the asphalt/polymer mixture.  
     
     
         9 . The method of  claim 1  where the crosslinker is present in an amount ranging from about 0.01 to about 0.75 wt %, based on the weight of the asphalt/polymer mixture.  
     
     
         10 . The method of  claim 1  further comprising adding a metal oxide activator to the asphalt.  
     
     
         11 . The method of  claim 10  where the metal oxide activator is zinc oxide.  
     
     
         12 . A method for preparing asphalt and polymer compositions comprising: 
 heating an asphalt;    adding an elastomeric styrene-butadiene copolymer and an inorganic acid to the asphalt in any order to form a mixture, where the proportion of inorganic acid ranges from about 0.05 to about 1 wt % based on the total mixture;    adding a crosslinker to the mixture after the addition of the acid; and    curing the mixture to give a polymer modified asphalt (PMA).    
     
     
         13 . The method of  claim 12  where the inorganic acid is selected from the group consisting of phosphoric acid, polyphosphoric acid, sulfuric acid, hydrochloric acid, nitric acid, and mixtures thereof.  
     
     
         14 . The method of  claim 12  where the crosslinker is selected from the group consisting of sulfur, mercaptobenzothiazoles and metal salts thereof, thiurams, dithiocarbamates, sulfur-containing oxazoles, thiazole derivatives, and mixtures thereof.  
     
     
         15 . The method of  claim 12  where the PMA has an improved high temperature property as compared with an identical PMA absent the inorganic acid, where the property is selected from the group consisting of ODSR and RTFO fail temperatures and combinations thereof.  
     
     
         16 . The method of  claim 12  where the elastomeric polymer comprises from about 1 to about 20 wt % of the asphalt/polymer mixture.  
     
     
         17 . The method of  claim 12  where the crosslinker is present in an amount ranging from about 0.01 to about 0.75 wt %, based on the weight of the asphalt/polymer mixture.  
     
     
         18 . The method of  claim 12  where the PMA is produced in commercial scale quantities.  
     
     
         19 . The method of  claim 12  further comprising adding a metal oxide activator to the asphalt.  
     
     
         20 . The method of  claim 19  where the metal oxide activator is zinc oxide.  
     
     
         21 . A polymer modified asphalt (PMA) composition prepared by the method comprising: 
 heating an asphalt;    adding an elastomeric polymer and an inorganic acid to the asphalt in any order to form a mixture, where the proportion of inorganic acid ranges from about 0.05 to about 2 wt % based on the total mixture;    adding a crosslinker to the mixture after the addition of the acid; and    curing the mixture to give a polymer modified asphalt (PMA).    
     
     
         22 . The PMA of  claim 21  where the elastomeric polymer is a vinyl aromatic/conjugated diene elastomer.  
     
     
         23 . The PMA of  claim 22  where the elastomeric polymer is a styrene-butadiene copolymer.  
     
     
         24 . The PMA of  claim 21  where the inorganic acid is selected from the group consisting of phosphoric acid, polyphosphoric acid, sulfuric acid, hydrochloric acid, nitric acid, and mixtures thereof.  
     
     
         25 . The PMA of  claim 21  where the proportion of inorganic acid ranges from about 0.05 to about 1 wt % based on the total mixture.  
     
     
         26 . The PMA of  claim 21  where the crosslinker is selected from the group consisting of sulfur, mercaptobenzothiazoles and metal salts thereof, thiurams, dithiocarbamates, sulfur-containing oxazoles, thiazole derivatives, and mixtures thereof.  
     
     
         27 . The PMA of  claim 21  where the PMA has an improved high temperature property as compared with an identical PMA absent the inorganic acid, where the property is selected from the group consisting of ODSR and RTFO fail temperatures and combinations thereof.  
     
     
         28 . The PMA of  claim 21  where the elastomeric polymer comprises from about 1 to about 20 wt % of the asphalt/polymer mixture.  
     
     
         29 . The PMA of  claim 21  where the crosslinker is present in an amount ranging from about 0.01 to about 0.75 wt %, based on the weight of the asphalt/polymer mixture.  
     
     
         30 . The PMA of  claim 21  where the method further comprises adding a metal oxide activator to the asphalt.  
     
     
         31 . The PMA of  claim 30  where the metal oxide activator is zinc oxide.  
     
     
         32 . A road made from the PMA of  claim 21  and aggregate.  
     
     
         33 . A roof sealed with the PMA of  claim 21 .  
     
     
         34 . A method of sealing a roof with PMA comprising heating the PMA of  claim 21  and distributing it over at least a portion of roof surface.  
     
     
         35 . A method of road building comprising combining the PMA of  claim 21  with aggregate to form a road paving material, and using the material to form road pavement.  
     
     
         36 . A polymer modified asphalt (PMA) composition prepared by the method comprising: 
 heating an asphalt;    adding an elastomeric styrene-butadiene copolymer and an inorganic acid to the asphalt in any order to form a mixture, where the proportion of inorganic acid ranges from about 0.05 to about 1 wt % based on the total mixture;    adding a crosslinker to the mixture after the addition of the acid; and    curing the mixture to give a polymer modified asphalt (PMA).    
     
     
         37 . The PMA of  claim 36  where the inorganic acid is selected from the group consisting of phosphoric acid, polyphosphoric acid, sulfuric acid, hydrochloric acid, nitric acid, and mixtures thereof.  
     
     
         38 . The PMA of  claim 36  where the crosslinker is selected from the group consisting of sulfur, mercaptobenzothiazoles and metal salts thereof, thiurams, dithiocarbamates, sulfur-containing oxazoles, thiazole derivatives, and mixtures thereof.  
     
     
         39 . The PMA of  claim 36  where the PMA has an improved high temperature property as compared with an identical PMA absent the inorganic acid, where the property is selected from the group consisting of ODSR and RTFO fail temperatures and combinations thereof.  
     
     
         40 . The PMA of  claim 36  where the elastomeric polymer comprises from about 1 to about 20 wt % of the asphalt/polymer mixture.  
     
     
         41 . The PMA of  claim 36  where the crosslinker is present in an amount ranging from about 0.01 to about 0.75 wt %, based on the weight of the asphalt/polymer mixture.  
     
     
         42 . The PMA of  claim 36  where the method further comprises adding a metal oxide activator to the asphalt.  
     
     
         43 . The PMA of  claim 42  where the metal oxide activator is zinc oxide.  
     
     
         44 . A method of recycling asphalt comprising physically removing asphalt from a location and reducing the size of the removed asphalt, heating the removed asphalt, adding an inorganic acid to the asphalt to form a mixture, adding a crosslinker to the mixture after the acid is added.  
     
     
         45 . The method of  claim 44  further comprising an elastomeric polymer to the asphalt.  
     
     
         46 . Recycled asphalt made by the process of  claim 44 .  
     
     
         47 . Aggregate comprising a PMA at least partially coating the aggregate, where the PMA comprises asphalt, an elastomeric polymer, an inorganic acid, and a crosslinker, where the crosslinker was added to the asphalt after the inorganic acid.