The vinyl industry is suggesting that a safe, new material developed by researchers could replace stabilizers made from heavy metals like lead.
The material is the most promising development in a six-year, $6 million cooperative research campaign funded by 21 companies, and looks like it can be commercialized, said Charles Wilkes, a director of the Edison Polymer Innovation Corp. in Akron, Ohio, which holds the rights to administer licenses for the research.
The stabilizer work was announced April 19 by researchers at the College of William and Mary in Williamsburg, Va.
The PVC industry has been under pressure from governments and environmentalists to stop using toxic heavy metals. The European industry has committed to the European Union that it no longer will use lead and cadmium.
The replacement touted by researchers is an ester thiol, which appears to be safe, said William Starnes, a chemistry professor at William and Mary and the material's developer.
Commercialization trials are proceeding and researchers should have a better idea by this summer if the material is cost-effective, said Wilkes, who also is president of Pilgrim Consulting Group in Akron.
``The initial results look pretty good,'' Wilkes said. ``I know there is tremendous interest among companies in having stabilizers without metals, particularly without heavy metals.''
Wilkes said ester thiols could be used in a range of both rigid applications, like siding on houses and window profiles, and flexible applications such as packaging and wire and cable covering.
The compounds also potentially could be used as plasticizers, replacing phthalates, another group of vinyl additives that sometimes raises health concerns. While research supports using them as plasticizers, Wilkes said ester thiols may be too expensive for that purpose.
Starnes has one patent on the research and is applying for others. The College of William and Mary, Starnes, and the EPIC program all could receive some product royalties or licensing fees if the work is commercialized.
The industry nearly is done with the EPIC research, which Wilkes said has produced some successes and some disappointments.
He said research on ``living radical polymerization'' is the second-most promising development, although it's too soon to say if it will yield commercial applications. That research could allow for PVC to be flexible, behaving as if it contains plasticizer, but the chemicals would be bonded in, he said.
The concern with some plasticizers has been that because they are loosely bonded to the PVC, they can leach out and come into contact with people when used in toys or medical products.
The living radical polymerization research also could yield PVC that maintains its strength at higher temperatures, Wilkes said.
Other research produced useful information on topics like better predicting the long-term performance of PVC with short-term tests in applications like pipe. But he said the research was not able to find metallocenes that work in PVC, a long-sought goal.