Long-sought approval for the use of polyethylene naphthalate in food-contact applications came April 8, when the U.S. Food and Drug Administration issued a letter of nonobjection to Eastman Chemical Co. Jim Caldwell, business market manager for the Kingsport, Tenn., resin maker's PEN business, said Eastman applied for the approval in 1988. PEN is a cousin to widely used PET.
``The nonobjection letter was for the homopolymer only,'' Caldwell said. ``We expect copolymer approval to be given later.''
Tom Snapp, director of business development for Eastman's PEN polymer, said Shell Chemical Co. and Amoco Chemical Co. jointly applied for nonobjection letters on the copolymer version of PEN.
Snapp said the company was happy to have the FDA letter, even though it took eight years, because of the resin's potential in packaging and other applications.
``We are happy that the FDA was very cautious with the review process,'' he said. ``There were a number of issues it had to decide, including environmental concerns, and how the resin should be classified.''
Snapp said containers of PEN will carry the Washington-based Society of the Plastics Industry Inc.'s resin identification code ``7,'' for ``other.'' He said Eastman has been producing PEN at its Kingsport complex since August, and that it has capacity for about 22 million pounds per year.
``Our ability to produce it has been limited by the availability of the monomer,'' Caldwell said, ``but we are confident that we will be able to overcome that.''
The nonobjection letter from the FDA is significant, since it means U.S. package and container makers will be able to use PEN for food products.
The resin has been touted as a packaging material because it has attractive barrier properties and is highly heat-tolerant, which is attractive to food packagers that fill containers with cooked or heated foods.
PEN's use until now has been limited by scarce supplies of one of its key ingredients, 2,6 napthalene dicarboxylate. Amoco, the only North American commercial supplier, last year ramped up production of NDC at its Decatur, Ala., plant.
Another stumbling block to commercialization of PEN is its cost. Jeff Toth, marketing manger for fine acids for packaging for Amoco, said NDC monomer costs about $1.50 per pound, so the PEN produced from it would be even more expensive.
One of the prime packaging targets for PEN is the beer industry, where large producers have been interested in using plastic packaging but blocked by PET's comparatively inadequate oxygen barrier properties.
``We have a number of beer producers who are interested in PEN,'' Caldwell said. ``They have indicated that they would like to have some of the advantages that carbonated soft drink producers have from plastic.''
Although PET can be used in hot-fill applications, it works only when the polymer is heat set, while PEN can be filled at temperatures about 122§ F hotter than PET without being heat set.
``In the long term, we see PEN selling at four to five times the price of PET,'' Caldwell said. ``It has to go where PET can't, and we think there are some very good markets for it out there.''
Experiments with PEN containers have been successful in other countries, and some packaging makers are testing PEN/PET blends to combine the best attributes of both and reduce the cost.
In Uruguay, Coca-Cola Co. test marketed a PEN returnable, refillable bottle for fruit juice, using resin produced by Teijin Ltd. of Tokyo. In England, Carters Ltd. of Nottingham, England, is using both one-way and refillable PEN bottles for a fruit-juice product, using Shell Chemical Co. resins.
Shelley Steele, market manager for Johnson Controls Inc.'s plastic container division in Manchester, Mich., said her company was interested in using PEN to make bottles.
``We are very excited about PEN in food applications,'' she said. ``Although the fact that only the homopolymer is approved, and the cost, are both of concern, we have several projects looking at PEN.''