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Plastic additives: Pipe processors, and others, benefit as Dover doubles, and then doubles again, its antioxidant capacity

Plastic additives and chemicals supplier Dover Chemicals recently doubled the capacity it has available for its patented Doverphos S-9228 high-performance phosphite antioxidant. Buyers of these additives tend to be plastics suppliers and plastics compounders, but the real benefactors will be processors, including those of polyethylene water pipe and tanks, explained Dover's Jack Teat in an interview with PlasticsToday.

Doverphos S-9228 is often used as a secondary antioxidant in polyolefins, though also in polycarbonate, explained Tate, executive VP. His company has offered the additive for some years but he said the doubling of capacity last year was a significant move. The supplier made "a fundamental step change" in its manufacturing process that enabled increased throughout, and now is adding additional plant and equipment to double the capacity yet again by mid-2011. "People want it but we haven't been able to meet all of the demand," noted Teat; the recent capacity expansion and the one ongoing should correct that situation.

All of which brings us back to the question: What's in it for pipe processors? As processors of potable polyethylene water pipes and PE water tanks know, legislation is being discussed or introduced around the world that will place stricter limits on the amount of additives that can legally leach into the water passing through these pipes. The large molecules of the Dover antioxidant don't move very much once ensconced within a compound, and compounders need not use as much of it to get the required effect. "There are products that compete with this (Doverphos S-9228) that don't pass REACH, and this one will," added Teat. He noted, "There is lots of legislation being discussed regarding additives in water, so we think we've got a winner here." REACH is the European legislation on Registration, Evaluation, Authorization and Restriction of Chemical substances.

The additive's properties include high molecular weight, low volatility, and high phosphorous content. Polyethylene pipes and tanks are not the only applications in which these AOs see use; it sees use in polypropylene (PP), high density polyethylene (HDPE), linear low density polyethylene (LLDPE), and high temperature polymers such as polyamides, polyesters and polycarbonate (PC).

In related news, Dover (Dover, OH) has also introduced LGP-11 liquid phosphite antioxidant, which it claims is the first suitable liquid alternative to TNPP. The liquid alternative from Dover has "large molecules, so it has very low migration" from a finished product, explained Don Stevenson, VP technology at the supplier. He said it processes well and its high levels of phosphite ensure good efficacy of the additive. All of the materials used to make it are non-toxic and are biodegradable.

LGP-11 is Dover's alternative to one of its best-established phosphite additives, Doverplus TNPP nonylphenol. There has been significant interest in the new additive since its introduction, says Teat. "We still believe TNPP (trisnonylphenyl phosphite) will continue to be the top phosphite used," explains Stevenson. "But for those markets and customers concerned with nonylphenol, this is a good replacement." Concerns have been raised about possible harmful effects of workers who come into contact with the additive.

Dover is obtaining FDA and REACH approvals for the LGP-11 material now, and expects these by mid-year, so that commercialization should begin in early 2012. Test customers already are working with the additive.

Regarding REACH, Teat said his company has noticed that countries outside of the European Union also are adopting REACH-like standards, citing specifically Taiwan. "We expect to see this in lots of other places soon too," he predicted.

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