The molecule is simple, created by polymerizing the reactive double-bond in fourcarbon isobutene (iC4). By varying the lengths of the single- strand chain, PIBs become inherently versatile: The molecular weight may range from 350 (a thin fluid) to 3,500 (a very viscous fluid) to several millions (solids of varying rigidity). One doublebond remains in the molecule, an ideal site for dozens of potential chemical reactions leading to hundreds of potential products. If the lone double-bond is at the end of the molecule, its highly reactive (HR) PIB; if its somewhere else, its conventional PIB.

PIB has a multitude of offshoots. Reacted with maleic anhydride, it forms polyisobutenyl- succinic-anhydride (PIBSA), a basic building block for dispersants in lube oils and detergents in fuels. Another variant is polyisobutylene-succinimide (PIBSI), an antioxidant emulsifier in soluble metalworking fluids and a lube additive building block.

ULTIMATE VARIETY

From our point of view, says John Uhran, global business manager for viscosity modifiers at Lubrizol in Wickliffe Ohio, there are four general uses of PIB in lubes and fuels: viscosity index improvers in automotive and industrial gear oils; thickeners in greases; smoke-suppressants in two-stroke oils; and building blocks for dispersants – which is where PIBSA and PIBSI play a role.

There are some markets for PIB outside of fuels and lubes, he adds, but they are relatively small compared with our industry.

Small maybe, but compelling. Mark Roll, the Houston-based vice president of specialty chemical marketer Soltex, notes a host of disparate applications. PIBs natural water-blocking capability makes it ideal for wood coatings, preservatives, deck paints and as a protective fill in copper or fiber-optic cables. Its power as an emulsifier leads to use in explosives, and as a emulsifying resin in various coatings. Its polarity makes it a good carrier for process chemicals. And solid PIB makes a good polymer modification ingredient for plastics, he says.

PIBs natural tackiness makes it the magic ingredient in industrial cling-film. Polyethylene provides strength for the film, while PIB migrates to the surface and sticks to whatever is being wrapped. Tackiness and PIBs completely nontoxic nature also make it a key ingredient for lipstick, eyeshadow, sunscreen and other personal-care products. Chances are, youve even chewed it – chewing gum contains polybutene.

Besides being nontoxic itself, polybutene does not support microbial growth. If you compare a mineral oil and a PIB derivative, PIB is not going to let the bugs grow, says Gabrielle Gabby Massoud, Soltexs new product development manager. Thats important in metalworking, and in food-grade lubricants. We sell a lot of PIBs for incidental food contact-we even have Kosher and Halal Food Authority approvals.

Another new application is using polybutene in electronics manufacturing, Massoud continues. The PIB unzips at a certain temperature and flashes off to leave the circuit chip nice and clean.

But sources agree the greatest use of PIB is in additives for lubricants and fuels, and even as a lubricant itself.

CLEAN AND BRIGHT

Some PIBs are used as a substitute for bright stock, the very heavyweight API Group I base oil that has grown scarce as refiners turn from solvent refining to embrace newer processes. Advocates say PIBs offer a number of advantages over bright stock, beyond the security-of-supply issue. They have better viscosity indices; they are much more oxidatively and hydrolytically stable; and being a synthetic product, they dont have the cats and dogs normally present in refined products. So PIBs burn cleaner, making them ideal for two-stroke engines oils (think of the growing moped markets of Asia and Latin America) and marine applications where blow-by gases from huge diesel engines are a harsh fact of life for lubricants.

Will PIBs ever completely replace bright stock? This is one area we are investigating, replies Joseph Palm, PIB market and asset manager for PIB producer Ineos Oligomers, based in League City, Texas. Right now, it seems to be man˜ana – there will be something, but its not there yet. Marine is a potentially good market, but theres been a real downturn because of the recession. I think the recession is masking the reduced availability of Group I oils.

Others concur. Martin Bannon, component manager at Linden, N.J.-based additive maker Infineum, says, The marine market should begin to grow again when the world economy improves, and it may significantly increase demand for PIB if Group I plants continue to close.

One concern about PIBs is their lesser solvency compared to bright stock. Some suggest overcoming this by blending PIB and naphthenic base oils. Soltexs Massoud offers another alternative, saying a PIB/alkylate combination might give solvency and viscosity closer to what people need if the economics support a changeover..

Lubrizols Uhran says PIBs are appearing more frequently in industrial gear oils and have long been used as thickeners in automotive gear oils. Usage in automotive gear oils may decline over time, though, as gear boxes and transmissions become more demanding. In many cases were actually moving away from PIB to other specially designed viscosity index improvers.

THE ADDITIVE CONNECTION

PIB goes beyond base stock, though. PIBSA – its number one derivative – is like a carpenters hammer for additive producers.

PIBs used for lubricant additives cluster around molecular weights of 1,000 or 2,300, while those used in metalworking tend to be under 1,000. Dispersants derived from PIB and PIBSA have two main uses. Added to motor oils they disperse carbon soot and prevent sludging, and in diesel fuels they remove engine deposits.

The market for dispersants is changing because the requirements to reduce SAPS [sulfated ash, phosphorus and sulfur] in engine oils is restricting the use of many traditional components, says John Pudelski, Lubrizols engine oils component technology manager. So formulators reliance on PIB and PIBSA is increasing. Thats one component class we can use as much as we want, with respect to SAPS limits.

Blenders seeking large volumes of engine oil additives typically flock to the Big 4 additive companies – Lubrizol, Infineum, Afton and Chevron Oronite – which produce their own PIBs and/or derivatives. More recently, Dover Chemical has moved into smaller PIBSA markets, buying polybutene and making a range of specialty derivatives.

Initially were looking for niche applications, volumes up to a few million pounds per year, says Brad Barth, business product manager at the Dover, Ohio-based company. We now have people coming to us for different chemistries, esters of PIBSA and niche markets as well. Anything youre looking to disperse, PIBSAs and the succinimides and derivatives, can be a good choice. We also see an opportunity for PIBSA in metalworking, because PIBSA can be used with other additives as a sulfonate replacement in emulsifiers.

COMMODITY OR SPECIALTY?

PIBs have been around for decades; are they commodities? It depends. Mark Roll of Soltex says, The standard grades have molecular weights of 950 and 1,300, and those comprise more than 80 percent of the market. That range is also the sweet spot in the manufacturing process. As a result, he says, the mid-weight PIBs remain something of a commodity, while less-common PIBs and derivatives are priced like specialty chemicals.

Randy Redd, business director of polyisobutylene for Texas Petrochemicals LP, says outright, PIB is not a commodity. Its a specialty chemical sold on technical performance. Our materials tend to be priced depending on value and use, and different products have different margins. Texas Petrochemicals boasts of being the worlds largest merchant marketer of PIB; last fall it completed a major expansion that roughly doubled PIB capacity at its chemical plant in Houston, and significantly raised its output of highly reactive PIB.

The molecules composition, whether conventional or highly reactive, is a big determinant of value, Roll explains. In HR PIB, for example, 80- plus percent of the doublebonds in the molecule are in the alpha terminal (end) position. By having the bonds primarily in the alpha position, you get more reactivity, cleaner burn and better action in use, Redd says. For our additives customers, the higher reactivity means their equipment is more productive in manufacturing the PIBSA and PIBSI molecules.

The highly reactive molecule is now being speced into additive packages, he continues. He notes that while overall sales of additives are linked to the growth of passenger car motor oil and miles driven, there is an internal switch to HR. That was the driver for doubling our plant capacity, he says. We are always working on new technology.

Of course, if you talk to companies that make conventional polybutene, you get a somewhat different picture. My customers tell me that sometimes theres an advantage for the highly reactive material, and sometimes theres not, says Joseph Palm of Ineos.

The PIB molecule is only the first part of the story. A lot of the energy in developing performance goes into converting PIB to PIBSA, says Lubrizols Pudelski, but even more focus, creativity and investment goes into making dispersants from the PIBSA – thats where most of the patents are.

SUPPLY AND DEMAND

Ten years ago, PIB was way oversupplied, says Roll of Soltex. Back then, there was no differentiation in market value across the whole range of product, but today there is. Several producers left the business or closed plant capacity in the 90s, and in general the market has gotten tighter. If you look at nameplate capacity, it looks like there is plenty of polybutene supply all over the world. But that is a little misleading.

Pricing depends to some extent on being nearby. Most PIBs are viscous enough that they must be heated to be pumpable, so long-distance transportation can be problematic. Another pricing variable is the chemical stream – natural gas or naphtha – used to make the PIB.

Palm observes that feedstock supply is the biggest concern currently. We could have all the PIB plant capacity in the world but you need the isobutene to produce it, and I think thats where the market is tight, he says. Look at the market for polyethylene: Most of the crackers in North America are NGL crackers (natural gas, light crackers), and theyre making ethylene because the incentive in this country is to make polyethylene. In Asia most PIBs are naphtha-based.

North America represents about half the total demand for PIBs, and Asia and Europe consume most of the rest. Sources acknowledge a dramatic drop-off in business at the end of 2008 due to the global recession, but are glad to report an uptick since June.

Some see Latin America as a growth market, fed by imports and by native PIBs supplied by Polibutenos Argentinos and Brazils Polibutenos Industrias Quimicas. In Europe, BASF also continues to expand its PIB capacity. And all agree that Asia is far and away the fastest-growing market; it almost quadrupled in the last few years, says Redd at Texas Petrochemicals.

We sell in nine countries, he says. We even export to Europe. Additives are a global market and the PIB market in general is becoming global. In the modern world, you haveto think on global terms.