Polymers and their use in asphalt compositions and asphalt concretes

Abstract

A modified asphalt composition comprising a naphthenic asphalt, and a high-vinyl block copolymer is presented. The modified asphalt composition is prepared by combining a naphthenic asphalt and a high-vinyl block copolymer. Further an asphalt concrete is presented, such concrete comprises an asphalt, a functionalized block copolymer, and a siliceous aggregate. A diblock copolymer is presented, such copolymer comprises a vinyl block comprising conjugated vinyl aromatic units, a diene block comprising conjugated diene units and substantially devoid of a tapered block section between the vinyl block and the diene block wherein the diblock copolymer comprises a vinyl content of at least about 20%, and a molecular weight of at least about 50,000.

1 . A modified asphalt composition comprising: 
 a naphthenic asphalt; and    a high-vinyl block copolymer.    
   
   
       2 . The composition of  claim 1 , where the naphthenic asphalt comprises a net excess of acidic compounds.  
   
   
       3 . The composition of  claim 2 , where the naphthenic asphalt comprises an acid value of from about 1.5 to about 5 mg KOH/g.  
   
   
       4 . The composition of  claim 1 , where the high-vinyl block copolymer comprises a diblock copolymer that comprises one block including vinyl aromatic units and one block comprising diene units.  
   
   
       5 . The composition of  claim 4 , where the block copolymer is substantially devoid of a tapered section.  
   
   
       6 . The composition of  claim 4 , where the block copolymer comprises a styrene content that is greater than about 10% by weight of the block copolymer.  
   
   
       7 . The composition of  claim 4 , where the block copolymer comprises a weight average molecular weight of at least 50 kg/mol and a molecular weight distribution of less than about 2.  
   
   
       8 . The composition of  claim 4 , where the diene block comprises at least about 15% by weight of its units in the vinyl configuration.  
   
   
       9 . The composition of  claim 4 , wherein a gel content of the block copolymer comprises less than about 1.5% by weight when tested by the toluene insoluble test.  
   
   
       10 . The composition of  claim 1 , wherein the high-vinyl block copolymer further comprises a curing agent.  
   
   
       11 . An asphalt concrete comprising: 
 an asphalt;    a functionalized block copolymer; and    a siliceous aggregate.    
   
   
       12 . The asphalt concrete of  claim 11 , where the functionalized block copolymer includes at least one diene block, at least one vinyl aromatic block, and at least one terminal functional group.  
   
   
       13 . The asphalt concrete of  claim 12 , where the functionalized block copolymer is defined by the formula  
       α-π-θ-ω 
     where α comprises a hydrogen atom or a functional group, π comprises a diene block, θ comprises a vinyl aromatic block, and ω comprises a hydrogen atom or a functional group, wherein at least one of α or α comprise a functional group.  
   
   
       14 . The asphalt concrete of  claim 13 , where the diene block comprises units deriving from conjugated dienes and where the vinyl aromatic block comprises groups deriving from vinyl aromatic monomer.  
   
   
       15 . The asphalt concrete of  claim 14 , where the at least one functional group comprises a silicon-containing group.  
   
   
       16 . The asphalt concrete of  claim 18 , wherein the at least one terminal functional group comprises the formula  
       Si(R 1 ) 3    
     where each R 1  comprises one of the group consisting of hydrocarbyl, substituted hydrocarbyl, and alkoxy groups.  
   
   
       17 . The asphalt concrete of  claim 15 , where the silicon-containing group comprises a siloxane derived compound comprising the formula  
       (R 1 ) 4-z Si(OR 2 ) z    
     where each R 1  comprises one of the group consisting of a halogen, a hydrocarbyl and a substituted hydrocarbyl group, each R 2  comprises either a hydrocarbyl or substituted hydrocarbyl group, and z comprises an integer from 1 to 4.  
   
   
       18 . A diblock copolymer comprising: 
 a vinyl aromatic block comprising conjugated vinyl aromatic units;    a diene block comprising conjugated diene units and substantially devoid of a tapered block section between the vinyl aromatic block and the diene block wherein the diblock copolymer comprises a vinyl content of at least about 15%, and a molecular weight of at least about 50,000.    
   
   
       19 . The diblock copolymer of  claim 18 , where the styrene content comprises from about 25% by weight of the diblock copolymer to about 35% by weight of the diblock copolymer.  
   
   
       20 . The diblock copolymer of  claim 18 , where the diblock copolymer comprises a molecular weight distribution of less than about 1.2.  
   
   
       21 . The diblock copolymer of  claim 20 , where the weight average molecular weight comprises from about 100 kg/mol to 500 kg/mol.  
   
   
       22 . The diblock copolymer of  claim 21 , where the gel content comprises less than about 1% by weight when tested by the toluene insoluble test.  
   
   
       23 . The diblock copolymer of  claim 18 , further wherein the block copolymer comprises a functional group attached to either the vinyl block or the diene block.  
   
   
       24 . The diblock copolymer of  claim 23 , where the functional group comprises a silicon-containing functional group.  
   
   
       25 . The diblock copolymer of  claim 24 , where the silicon-containing functional group comprises the formula  
       Si(R 1 ) 3    
     where each R 1  comprises one of the group consisting of hydrocarbyl, substituted hydrocarbyl, and alkoxy groups.  
   
   
       26 . A method of preparing a diblock copolymer comprising: 
 anionically polymerizing a first charge of diene monomer with a functionalized initiator in the presence of a vinyl modifier thereby forming a polymer having a vinyl content, and whereby said polymerizing comprises consumption of substantially all of said diene monomer; and    polymerizing a second charge of vinyl aromatic monomer in the presence of said polymer forming a diblock copolymer comprising a diene block and a vinyl block, whereby said diblock copolymer comprises a vinyl content of at least about 20%, and a molecular weight of at least about 50,000.    
   
   
       27 . The method of  claim 26 , where the consumption of said diene monomer comprises at least 90% of the first-polymerized monomer.  
   
   
       28 . The method of  claim 26 , where the amount of vinyl modifier present comprises less than an amount necessary to randomize the vinyl aromatic monomer or the diene monomer.  
   
   
       29 . The method of  claim 26 , further comprising functionalizing the copolymer with a silicon-containing functional group of the formula  
       Si(R 1 ) 3    
     where each R 1  comprises one of the group consisting of hydrocarbyl, substituted hydrocarbyl, and alkoxy groups.