Recent research into manufacturing closures made partly of bio-based resin by India's Essel Propack Ltd. has upset some in the recycling industry, even as company officials deny that they plan to introduce the product into the most commonly recycled plastics materials' reclamation streams.
Essel Propack, which makes tubes, caps and closures, has been testing a hybrid of polypropylene and what the firm originally said was polylactic acid for tube closures. In a July 20 telephone interview, Kerry Dodds, manager of Essel Propack's molding plant in Danville, Va., said the bio-based material more accurately could be termed “starch-based resin,” not PLA.
The company developed the hybrid caps at the request of an undisclosed North American customer and has successfully batch-tested them at Danville Community College. Commercialization is likely in the near future once pricing is ironed out, Dodds said.
That research and development work prompted the National Association for PET Container Resources in Sonoma, Calif., to send a letter July 6 to Ted Sojourner, regional Vice President of Essel Propack's tubes and laminates business in the Americas.
In the letter, NAPCOR cautioned Sojourner that the R&D project “likely runs counter to your customers' motivations and intentions regarding this material and we urge you to take the time to fully understand the implications that these closures may have when used on containers made from non-PLA resins.”
In a July 14 telephone interview, Mike Schedler, NAPCOR's technical director, said the group is concerned whenever companies appear to be designing bio-based products without regard to their effects on recycling.
“During the process of recycling PET bottles, float/sink technology is used to float off the PP [and] polyethylene closures in use today, as well as in some cases residual label [material]. If you inject a PLA cap into that mix, there's no way you can instruct people to take the caps off and recycle them. It's going to get into the mix,” he said.
Schedler said the problem is that material recovery facilities in the United States are generally not configured to successfully separate PLA from other materials with a float/sink process.
“Most of them are still employing a manual sort. There's just no way, when you have a burden depth of 9-20 inches, that those manual sorters can pick out one [material] from another. So you always have a spillover to some degree, whether it's 2 percent or 5 percent — depends on how well the MRF is run.
“Even if you had a high density [polyethylene] bottle in there, chances are that the closures are going to get in with the PET, and that really poses a problem in terms of extreme contamination for the PET, since the PLA and PET will sink. The technology that is being used to remove the PLA bottles as contaminants is not going to work on caps,” Schedler said.
Dodds said he appreciates NAPCOR's concern about the hazards of mixing incompatible materials during recycling, but doesn't think it's germane to Essel Propack's immediate R&D project.
“These caps are for tubes” and will have the Society of the Plastics Industry Inc. recycling symbol No. 7 (“other”) designation on the inside, he said.
“And they are caps. It's not like we have any intentions of going further with this and making bottles. It's not within our realm of possibilities.”
Dodds said Essel Propack's customer is seeking a cap that could degrade in a landfill, not something that could be recycled.
Schedler said that kind of “green” philosophy about PLA — which he said is more about brand owners' marketing instead of true environmental concern — is what's causing so much confusion in the plastics recycling industry.
“These guys are saying, 'It's going to disappear in a landfill in five years.' I haven't spoken to a landfill manager that would knowingly want that stuff in their landfill, because what you're saying is that it's going to continue to destabilize the landfill, No. 1.
“No. 2, it's going to generate methane. Nobody wants to generate methane. It's counter to what you're talking about in terms of global-warming issues. Even if you accept that it disappears, from a public value standpoint, it doesn't make any sense,” he said.
In its letter to Essel Propack, NAPCOR referenced design guidelines written in 1994 and last revised in 2008 by the Association of Postconsumer Plastic Recyclers in Washington.