Block copolymer and polymer modified bituminous binder composition for use in base course asphalt paving application

Abstract

The present invention provides a polymeric composition that includes a coupled block copolymer having a plurality of arms comprising at least two blocks of a monovinylaromatic hydrocarbon that are located on at least two of the plurality of arms, and at least one block of a conjugated diene located on at least one of the plurality of arms, and optionally one or more block copolymers comprising at least one block of monovinylaromatic hydrocarbon and at least one block of a conjugated diene, the block copolymer may be selected from linear copolymers, linear triblock copolymers, multiarm coupled block copolymers, and mixtures thereof. The molecular weight of the polymeric composition is in the range from about 100 kg/mol to about 400 kg/mol.

1 . A polymer modified bituminous binder composition for use as a base course in an asphalt paving application, comprising:
 about 90 to about 98% by weight of a bitumen component; and   about 2 to about 10% by weight of a block copolymer composition comprising
 (i) a copolymer comprising one block of a monovinylaromatic hydrocarbon and one block of a conjugated diene having a peak molecular weight from about 30,000 to about 78,000 and a vinyl content from about 35 to about 80 mol percent based upon the repeat monomer units in the conjugated diene block, and 
 (ii) optionally one or more block copolymers comprising at least two blocks of monovinylaromatic hydrocarbon and at least one block of a conjugated diene, the block copolymer selected from linear triblock copolymers having a peak molecular weight that is 1.5 to 3 times the peak molecular weight of the diblock copolymer, multiarm coupled block copolymers having a peak molecular weight that is 1.5 to 9.0 times the peak molecular weight of the diblock copolymer, and mixtures thereof, wherein each block copolymer has a vinyl content from 35 to 80 mol percent based on the number of repeat monomer units in the conjugated diene block, 
 wherein the polymer modified bituminous binder composition is utilized as a base course in a paving application. 
   
     
     
         2 . The polymer modified bituminous binder composition of  claim 1 , wherein the copolymer is present at a ratio of greater than 1:1. 
     
     
         3 . The polymer modified bituminous binder composition of  claim 1 , wherein the copolymer (i) is of the formula A-B and the block copolymer (ii) is selected from block copolymers of the formula A-B-A and (A-B) n X wherein with regard to the formulas A is a block of monovinyl aromatic hydrocarbon, B is a block of conjugated diene, n is an integer from 2 to 6 and X is a coupling agent residue. 
     
     
         4 . The polymer modified bituminous binder composition of  claim 1 , wherein the block copolymer composition comprises A-B and A-B-A wherein each A is styrene and each B is butadiene, the peak molecular weight of A-B is from 48,000 to 78,000 and vinyl content is from 46 to 70 mol percent based on the number of repeat monomer units in the conjugated diene block of A-B, and the peak molecular weight of A-B-A is 1.8 to 2.5 times the peak molecular weight of A-B and vinyl content is from 46 to 70 mol percent based on the number of repeat monomer units in the conjugated diene block of A-B-A, and the polystyrene content of A-B is from 25 to 35% and the polystyrene content of A-B-A is from 25 to 35%. 
     
     
         5 . The polymer modified bituminous binder composition of  claim 1 , further comprising the addition of a block copolymer of the formula C-D-C or (C-D) n X, wherein C is styrene, D is butadiene, isoprene or mixtures thereof, n is an integer from 2 to 6 and X is a coupling agent residue, and the additional block copolymer is added in an amount up to 30% by weight, of the total amount of block copolymer added. 
     
     
         6 . A polymeric composition comprising:
 (a) a coupled block copolymer having a plurality of arms comprising at least two blocks of a monovinylaromatic hydrocarbon and at least one block of a conjugated diene; and   (b) optionally one or more block copolymers comprising at least one block of monovinylaromatic hydrocarbon and at least one block of a conjugated diene, the block copolymer may be selected from linear copolymers, linear triblock copolymers, multiarm coupled block copolymers, and mixtures thereof.   wherein the molecular weight of the polymeric composition is in the range from about 100 kg/mol to about 400 kg/mol and the coupling efficiency is equal to or less than 40%.   
     
     
         7 . The polymeric composition of  claim 6 , further comprising a molecular weight of the polymeric composition is in the range from about 150 kg/mol to about 300 kg/mol. 
     
     
         8 . The polymeric composition of  claim 6 , wherein the coupled block copolymer includes two styrene end blocks located on at least two of the plurality of arms. 
     
     
         9 . The polymeric composition of  claim 6 , wherein the coupled block copolymer includes at least one butadiene block located on at least one of the plurality of arms. 
     
     
         10 . A polymeric composition comprising:
 a coupled styrene-butadiene-butadiene-styrene block copolymer containing at least two styrene arms having an absolute arm weight average molecular weight in the range from about 40 kg/mol to about 90 kg/mol and at least one butadiene arm having an absolute arm weight average molecular weight in the range from about 40 kg/mol to about 90 kg/mol, and a peak molecular weight in the range from about 100 kg/mol to about 400 kg/mol.   
     
     
         11 . The polymeric composition of  claim 10  further comprising a molecular weight of the polymeric composition is in the range from about 150 kg/mol to about 300 kg/mol. 
     
     
         12 . The polymeric composition of  claim 10 , wherein the polymeric composition includes a molecular weight of about 200 kg/mol. 
     
     
         13 . The polymeric composition of  claim 10 , wherein the block copolymer composition includes a degree of branching from about 3 to about 16. 
     
     
         14 . The polymeric composition of  claim 10 , further comprising a ratio of styrene to butadiene from about 10:90 to about 40:60. 
     
     
         15 . A polymer modified bituminous binder composition for use as a base course in an asphalt paving application, comprising:
 about 90 to about 98% by weight of a bitumen component; and   about 2 to about 10% by weight of a coupled block copolymer composition comprising:
 (a) a coupled block copolymer having a plurality of arms comprising at least two blocks of a monovinylaromatic hydrocarbon located on at least two of the plurality of arms, and at least one block of a conjugated diene located on at least one of the plurality of arms, and 
 (b) optionally one or more block copolymers comprising at least one block of monovinylaromatic hydrocarbon and at least one block of a conjugated diene, the block copolymer selected from linear triblock copolymers, multiarm coupled block copolymers, and mixtures thereof. 
 wherein the molecular weight of the polymeric composition is in the range from about 100 kg/mol to about 400 kg/mol. 
   
     
     
         16 . The polymer modified bituminous binder composition of  claim 15 , further comprising a molecular weight of the polymeric composition is in the range from about 150 kg/mol to about 300 kg/mol. 
     
     
         17 . The polymer modified bituminous binder composition of  claim 15 , wherein the polymeric composition includes a molecular weight of about 200 kg/mol. 
     
     
         18 . The polymer modified bituminous binder composition of  claim 15 , wherein the block copolymer composition includes a degree of branching from about 3 to about 16. 
     
     
         19 . The polymer modified bituminous binder composition of  claim 15 , further comprising a ratio of styrene to butadiene from about 15:85 to about 30:70. 
     
     
         20 . The polymer modified bituminous binder composition of  claim 15 , wherein the coupled block copolymer includes two styrene end blocks attached to two of the plurality of arms. 
     
     
         21 . The polymer modified bituminous binder composition of  claim 15 , wherein the coupled block copolymer includes at least one butadiene arms in the plurality of arms. 
     
     
         22 . The polymer modified bituminous binder composition of  claim 15 , wherein the coupled block copolymer includes at least two butadiene arms in the plurality of arms. 
     
     
         23 . The polymer modified bituminous binder composition of  claim 15 , further comprising a polymer content from about 5% to about 8%. 
     
     
         24 . The polymer modified bituminous binder composition of  claim 15 , further comprising a polymer content from about 6% to 7.5%. 
     
     
         25 . A process for preparing a coupled block copolymer composition, the process comprising the steps of:
 (a) providing a solvent at a temperature of about 40° C. to about 60° C.   (b) adding polystyrene and sec-butyl lithium to the solvent;   (c) allowing the reaction to proceed for about 45 minutes to about 2 hours;   (d) adding polystyrene for obtaining a predetermined molecular weight;   (e) adding sec-butyl lithium and butadiene;   (f) allowing polymerization to proceed from about 15 minutes to about 1 hour;   (e) adding a coupling agent; and
 terminating the reaction from about 5 minutes to about 30 minutes after the coupling agent was added by the addition of a terminating agent. 
   
     
     
         26 . The process for preparing a coupled block copolymer of  claim 25 , wherein about 152 g of polystyrene is added to about 6 liters of solvent. 
     
     
         27 . The process for preparing a coupled block copolymer of  claim 25 , wherein about 10.1 mmol of sec-butyl lithium is initially added to the solvent, and 19.7 mmol of sec-butyl-lithium and 835.2 g of butadiene is added thereafter.