The Shell Chemical Torrance Plant was built during World War II as part of a crash program to develop a synthetic rubber to replace the supplies of natural rubber that were cut off by Japanese invasions of Malaysia and Java. Shell actually developed the process for making 1,4-butadiene and built and operated that part of the plant for the United States Rubber Reserve Administration. Dow Chemical had a successful process for manufacturing styrene and built that part of the plant. The rubber to be manufactured was a copolymer of butadiene and styrene (SBR), and was the developmental part of the venture. Three separate lines for manufacturing SBR were built in Torrance, one each by US Rubber, Goodyear and Firestone. The SBR plant was shutdown after W.W.II, but was started up again during the Korean War by Midland Tire and Rubber, a subsidiary of Minnesota Mining and Manufacturing (3M).
In 1955, the government decided to dispose of all 14 rubber plants, and put them up for sale. Dow Chemical bid only for the Styrene plant, and there were separate bids for the copolymer plants, but only Shell Chemical bid for the purchase of the entire plant. Shell campaigned aggressively for the plant with congressional support, and was eventually the successful bidder. The transaction was actually completed in April 1955, and Shell established its Synthetic Rubber Sales Division at the Plant and assigned senior Shell managers to take over the various departments.
In the years that followed, Shell built up a position in the market for SBR, and modified and expanded the Torrance Plant to meet demands. The butadiene plant was modernized in 1956 when acetonitrile was substituted for acetone as the extraction solvent for separating butane from butylenes. Later, an acid extraction of amylene from refinery streams was added to permit preparation of pure isoprene. This was used as a feed stock for a new process to manufacture polyisoprene, which it was hoped would be a synthetic version of natural rubber. Styrene plant capacity was expanded in increments, but there were no major changes in the process over the period Shell operated the plant.
One of the earliest Shell initiatives in the polymers plant at Torrance was the production of a new latex designed for use in paint. Paint latex production was initiated in 1957, but Shell's product failed to gain much of a position in the market. Two problems with the product were its odor, and its freeze/thaw resistance. The largest early Shell initiative in the Copolymer area was in the production of cold, high solids latex for use in the manufacture of foam rubber. This product, S-2105 Latex and later a resin-reinforced version, S-7852, were designed primarily for mattress and pillow manufacture in the process used by US Rubber at their plant in Santa Ana, California. Although some quality problems were experienced in 1959, these were traced to a bad batch of soap used to manufacture the latex involved, and a "synthetic" soap developed in the Torrance Plant Laboratory, together with other formulation and process control modifications, led to a successful product that enjoyed many years of profitable operation for Shell. In the longer run, the foam rubber lost market share to foamed polyurethane, but that problem was not one that could be solved by Shell.
The first batches of Shell Isoprene Rubber or SIR were prepared in the Copolymer plant in about 1959, and soon thereafter a full scale polyisoprene polymerization and finishing units were added to the Copolymer Plant. Later still, a plant for converting the polyisoprene rubber cement to a high solids aqueous emulsion rubber latex was developed in the Synthetic Rubber Technical Center and carried into the plant. The development of these products at Torrance was the precursor to even larger scale production facilities at Belpre, Ohio. The process for making polyisoprene was catalyzed by butyl-lithium, and resulted in a product that was approximately 90% cis-polyisoprene. As it developed in the market place, this was not close enough to the 100% cis-configuration of natural rubber to permit complete substitution of the synthetic for the natural product. However, other synthetic polyisoprenes manufactured with a Ziegler-Natta type catalyst were much closer to the 98 % cis- level and were much more suitable for many applications such as the commercially critical tire market. Therefore Shell's venture into synthetic isoprene based rubber was not a commercial success.
However, the process of commercializing polyisoprene manufacture at Torrance did have a positive outcome. Learning to manufacture solution polymers on a commercial scale was a necessary step towards the production of the next generation of polymers, the block polymers of styrene and butadiene, and styrene and isoprene. These polymers were developed in the SRTC at Torrance, and brought into small scale production in the polyisoprene plant in 1963. The initial products, which were known at Delta polymers or D Polymers, were later commercialized as Kraton and other thermoplastic elastomers that still form the basis for a very successful and profitable business for Shell at its Belpre Plant.
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Comments or suggestions are welcome: Tom Williams, trw@rice.edu