Asphalt composition containing styrene-butadiene-styrene block copolymer having asymmetric polystyrene block

Abstract

The present invention provides a modified asphalt composition showing excellent ductility and thermal stability at low temperature and the resistance to permanent deformation at high temperature comprising i) 100 wt. part of natural asphalt; and ii) 0.5˜40 wt. part of asymmetric styrene-butadiene-styrene triblock copolymer having number average molecular weight of 20,000˜1,000,000. Modified asphalt composition of present invention can be used for pavement of road or manufacturing water proof sheet.

1 . A modified asphalt composition showing excellent ductility and thermal stability at low temperature and the resistance to permanent deformation at high temperature comprising i) 100 wt. part of natural asphalt; and ii) 0.5˜40 wt. part of asymmetric triblock copolymer having number average molecular weight of 20,000˜1,000,000 represented as following formula 1. 
       A-B-A′  (formula 1) 
     wherein 
 A represents a vinyl aromatic polymer block having number average molecular weight of 8,000˜30,000;  
 B represents a conjugated-diene polymer block or a conjugated-diene copolymer block having a small amount of vinyl aromatic monomers; and  
 A′ represents a vinyl aromatic polymer block having number average molecular weight of 500˜5,000;  
 wherein the weight amount of A and A′ block is 5˜40 wt % of total A-B-A′ triblock copolymer, and the percentage of vinyl aromatic monomer in the block A+A′ as to total vinyl aromatic monomer amount in A-B-A′ is 50˜98%.  
 
   
   
       2 . The modified asphalt composition according to  claim 1 , wherein said vinyl aromatic polymer block (A or A′) comprises monomers at least one selected from the group consisting of styrene, a-methylstyrene, o-methylstyrene, p-methylstyrene and p-tert-butylstyrene.  
   
   
       3 . The modified asphalt composition according to  claim 1 , wherein said vinyl aromatic monomer is a styrene.  
   
   
       4 . The modified asphalt composition according to  claim 1 , wherein said conjugated-diene polymer block (B) is a homopolymer block consisting of butadiene or a tapered block consisting of most of butadienes and a small amount of conjugated diene monomers.  
   
   
       5 . The modified asphalt composition according to  claim 1 , wherein the number average molecular weight of said compound of formula 1 is 50,000˜400,000.  
   
   
       6 . The modified asphalt composition according to  claim 1 , wherein said asphalt composition comprises i) 100 wt. part of natural asphalt and ii) 1˜20 wt. part of asymmetric triblock copolymer represented by formula 1.  
   
   
       7 . The modified asphalt composition according to  claim 1 , further comprising linear or radial block copolymer.  
   
   
       8 . A use of modified asphalt composition of  claim 1 , for pavement of road or manufacturing water proof sheet.