Thursday, October 20, 2011

Who Invented Kraton?

I saw in a trade journal that Kraton is celebrating it's 50th anniversary. Actually, it was the 50th anniversary of the Belpre Ohio plant where the stryeneic block copolymer is made. There are many variations of Kraton, but they all fall under the general umbrella of being tri-block copolymers with styreneic endblocks and a rubbery midblock. (If I remember correctly, half the styrene blocks are made first (anionic polymerization), then half the midblock is attached, and then midblcok portion is capped by a coupling agent. The coupling agent then brings to two halves of the polymer together to create the triblock product.) When heated to 100 oC or more, the endblocks soften and flow, but upon cooling they phase separate to form styreneic blobs in a rubbery matrix. Since the rubber is physically crosslinked, not chemically, the material can be processed with standard equipment and will reflow repeated, unlike vulcanized rubbers or other crosslinked rubbers. The rubber is used as the base for an immense number of materials - box sealing tapes, diaper tapes, footwear, as an additive to asphalt...

So the question occurred to me: who invented Kraton? There are lots of polymers where I can name the inventors: Carouthers invented nylon, Ziegler-Natta "invented" HDPE (or at least the catalyst that made it possible), Stephanie Kwolek invented Kevlar, Roy Plunkett invented Teflon,... So how come Shell has kept the inventors names under warps? I tried looking for relevant patents from the 1950's and 60's but didn't find anything that said to me: "Kraton!"

Any old Shell Chemical guys that can answer this? Considering that billions have been made from this material, someone should have had a pretty big reputation around the company.

No comments: