Published August 1998
This report, Supplement 4D to PEP Report 4C, Ethylene Propylene Copolymer and Terpolymer Rubbers, which was issued in 1990, reviews the technology for producing (ethylene-propylene-diene (EPDM). This report also reviews some cases for producing random ethylene-propylene copolymer (EPM).
EPDM elastomers are produced by three different processes: the solution process, the suspension process (also known as the slurry process), and the gas-phase process. Conventional Ziegler-Natta catalyst systems based on transition metals, such as V and Ti, are commercially used for most of these processes. Currently, metallocene catalyst systems based on Zr, Ti, or Hf also attract the industry's attention for EPDM production. Du Pont/Dow Elastomer, a joint venture between Du Pont and Dow Chemical, has started to produce EPDM by a solution process using Dow�s Insite™ metallocene catalyst. The gas-phase process developed by Union Carbide is also recently commercialized. In this report, we evaluate and compare these processes, which use either ethylidene norbornene (ENB) or 1,4-hexadiene (HD) as the nonconjugated diene in the terpolymer, and either Ziegler-Natta or metallocene catalyst systems for polymerization. The processes can be briefly described thus:
- Solution process for EPDM containing HD by Ziegler-Natta catalyst�the EPDM(HD) elastomer is made in a process presumably used commercially by Du Pont; the polymer is recovered without steam-stripping.
- Solution process for EPDM containing ENB by Insite™ metallocene catalyst�the EPDM(ENB) elastomer is produced in a manner similar to the solution process for EPDM(HD), but this process uses a high polymerization temperature, which allows a high resin concentration in the reactor effluent.
- Solution process for EPDM containing ENB by Ziegler-Natta catalyst�the EPDM(ENB) elastomer is produced in a conventional process with steam-stripping to recover the polymer.
- Gas-phase process for EPDM containing ENB by prepolymerized Ziegler-Natta catalyst�the EPDM(ENB) elastomer is made in a process presumably similar to the Commercial process used by Union Carbide.
- Suspension process for EPDM containing ENB by Ziegler-Natta catalyst�the EPDM(ENB) elastomer is produced in excess propylene.
In the EP elastomer industry, it is difficult to differentiate the market share of EPDM elastomers from EPM elastomers. We estimate that EPDM elastomers account for about 80�85% of total worldwide EP elastomer production. The worldwide production capacity for EP elastomers as of July 1998 was estimated at about 2.5 billion lb/y (1.14 million t/yr). In 1997, the world consumption of EP elastomers was estimated at about 1.59 billion lb/yr (720,000 t/yr).
