Blends of Styrene Butadiene Copolymers with Ethylene Acrylate Copolymers and Ethylene Based Wax for Asphalt Modification
The present invention is a polymer-modified asphalt composition comprising an elastomeric polymer blend, a low molecular weight plastomer and an un-modified asphalt. Asphalt compositions of the present invention demonstrate improved elasticity and stiffness compared to conventional polymer-modified asphalt compositions.
1 . A composition useful as an asphalt modifier comprising an elastomer and a low molecular weight plastomer, wherein the elastomer is a blend comprising (i) a first elastomer selected from the group consisting of ethylene/n-butyl acrylate/glycidyl methacrylate terpolymers, ethylene alkyl acrylate copolymers obtained by a tubular reactor process, and mixtures thereof and (ii) a second elastomer selected from the group consisting of styrene butadiene styrene block copolymers, styrene butadiene random copolymers and mixtures thereof.
2 . A composition of claim 1 wherein said first elastomer is an ethylene/n-butyl acrylate/glycidyl methacrylate terpolymer.
3 . A composition of claim 1 wherein said first elastomer is an ethylene alkyl acrylate copolymer obtained by a tubular reactor process.
4 . A composition of claim 1 wherein said second elastomer is a styrene butadiene styrene block copolymer.
5 . A composition of claim 1 where said second elastomer is a styrene butadiene random copolymer.
6 . A composition of claim 1 wherein said plastomer is a polyolefin wax.
7 . A composition of claim 6 wherein said polyolefin wax is a polyethylene wax.
8 . A composition of claim 1 wherein said plastomer is present in the composition in an amount of from about 1 to about 5 wt. % based on the total weight of the composition.
9 . A composition of claim 1 wherein said second elastomer is present in said blend in an amount of from about 25 wt. % to about 75 wt. %, based on the total weight of said blend.
10 . An asphalt composition comprising an un-modified asphalt, an elastomer and a low molecular weight plastomer, wherein the elastomer is a blend comprising (i) a first elastomer selected from the group consisting of ethylene/n-butyl acrylate/glycidyl methacrylate terpolymers, ethylene alkyl acrylate copolymer obtained by a tubular reactor process, and mixtures thereof and (ii) a second elastomer selected from the group consisting of styrene butadiene styrene block copolymers, styrene butadiene random copolymers and mixtures thereof.
11 . An asphalt composition of claim 10 wherein said elastomer and low molecular weight plastomer composition are present in the asphalt composition in an amount of from about 0.01 wt. % to about 25 wt. %, based on the total weight of said asphalt composition.
12 . A pavement comprising an asphalt composition comprising an un-modified asphalt, an elastomer and a low molecular weight plastomer, wherein the elastomer is a blend comprising (i) a first elastomer selected from the group consisting of ethylene/n-butyl acrylate/glycidyl methacrylate terpolymers, ethylene alkyl acrylate copolymer obtained by a tubular reactor process and mixtures thereof and (ii) a second elastomer selected from the group consisting of styrene butadiene styrene block copolymers, styrene butadiene random copolymers and mixtures thereof.
13 . A process for modifying an asphalt composition comprising the step of blending (i) a composition comprising an elastomer and a low molecular weight plastomer with (ii) an un-modified asphalt, wherein the elastomer is a blend comprising (i) a first elastomer selected from the group consisting of ethylene/n-butyl acrylate/glycidyl methacrylate terpolymers, ethylene alkyl acrylate copolymers obtained by a tubular reactor process and mixtures thereof; and (ii) a second elastomer selected from the group consisting of styrene butadiene styrene block copolymers, styrene butadiene random copolymers and mixtures thereof.