# US 7,608,650 B2 · Bitumen/rubber compositions crosslinked with polythiomorpholines, polysulfides and/or mercaptobenzimidazole

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- Number: US 7,608,650 B2
- Document ID: US7608650B2
- Status: Granted
- Kind: B2
- Application number: 12/367,303
- Filed: 2009-02-06
- Published: 2009-06-04
- Granted: 2009-10-27
- Earliest claimed: 2003-12-31
- Assignees: Fina Technology, Inc.
- Inventors: Paul Buras; William Lee; James Butler; Wendy Stanley
- Web page: https://patentgrep.com/patent/US7608650B2

## CPC

- E01C 7/18: of road-metal and bituminous binders {(for surface treatments except for penetration coverings, or for thin surface layers E01C7/353; bituminous mixtures C08L95/00)}
- C08L 95/00: Compositions of bituminous materials, e.g. asphalt, tar, pitch
- C08L 9/06: Copolymers with styrene
- C08L 81/04: Polysulfides
- E01C: CONSTRUCTION OF, OR SURFACES FOR, ROADS, SPORTS GROUNDS, OR THE LIKE; MACHINES OR AUXILIARY TOOLS FOR CONSTRUCTION OR REPAIR (forming roads or like surfaces by compacting or grading snow or ice E01H)
- C08L: COMPOSITIONS OF MACROMOLECULAR COMPOUNDS (compositions based on polymerisable monomers C08F, C08G; artificial filaments or fibres D01F; textile treating compositions D06)

## Abstract

Asphalt and elastomeric polymer compositions crosslinked with mixed polythiomorpholines or at least one alkyl polysulfide can give polymer modified asphalts (PMAs) with improved properties and/or reduced H2S evolution. When at least one alkyl polysulfide is used to completely or partially replace conventional crosslinkers such as S or MBT, mercaptobenzimidazole (MBI) may be optionally used as a co-crosslinker. The use of mixed polythiomorpholines as crosslinkers provide PMAs with better low temperature profiles (BBR m-values). The use of at least one alkyl polysulfide crosslinker gives PMAs with improved PAV-aged DSR results, and reduced H2S evolution. The use of at least one alkyl polysulfide crosslinker together with MBI may give PMAs with improved PAV DSR Fail Temperatures.

## Claims

### Claim 1

A method for preparing asphalt and polymer compositions comprising:
heating a mixture comprising asphalt, an elastomeric polymer, mercaptobenzimidazole and a crosslinker comprising at least one alkyl polysulfide; and
curing the mixture to form a polymer modified asphalt (PMA).

### Claim 2 (depends on 1)

The method of claim 1, wherein the crosslinker further comprises sulfur.

### Claim 3 (depends on 1)

The method of claim 1, where the crosslinker is absent elemental sulfur.

### Claim 4 (depends on 1)

The method of claim 1, wherein the crosslinker is absent mercaptobenzothiazole (MBT).

### Claim 5 (depends on 1)

The method of claim 1, wherein the PMA exhibits improved pressure aging vessel-dynamic shear rheometers (PAV-aged DSR) compared with an identical PMA absent the alkyl polysulfide.

### Claim 6 (depends on 1)

The method of claim 1, wherein the alkyl polysulfide has the structure
R13—S—S—R23
where R1 and R2 are independently straight, branched or cyclic alkyl groups, where R1 and R2 may be substituted with N, S and/or O, and the total number of carbon atoms in all R1 groups is 9 or greater and the total number of carbon atoms in all R2 groups is 9 or greater.

### Claim 7 (depends on 1)

The method of claim 1, wherein the elastomeric polymer comprises from about 1 to 20 wt % of the asphalt/polymer mixture.

### Claim 8 (depends on 1)

The method of claim 1, wherein the crosslinker is present in an amount ranging from about 0.01 to about 1 wt % based on the weight of the asphalt/polymer mixture.

### Claim 9 (depends on 1)

A polymer modified asphalt (PMA) composition prepared by the method of claim 1.

### Claim 10 (depends on 9)

A method of sealing a roof with the PMA comprising heating the PMA of claim 9 and distributing it over at least a portion of the roof.

### Claim 11 (depends on 9)

A method of forming a road comprising combining the PMA of claim 9 with aggregate to form a road paving material; and forming a road with the road paving material.

### Claim 12

A method of recycling asphalt comprising: physically removing asphalt from a location and, in any order, reducing a size of the removed asphalt; heating the removed asphalt; and adding a crosslinker to the removed asphalt, wherein the crosslinker comprises at least one alkyl polysulfide and mercaptobenzimidazole (MBI).

### Claim 13 (depends on 12)

Recycled asphalt formed by the process of claim 12.