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Occidental charts course for PVC recycling.

Occidental Charts Course For PVC Recycling

One year into its new role as a post-consumer PVC scrap recycler, the Polymers & Plastics Div. of Occidental Chemical Corp., Berwyn, Pa., is on its way to developing a recycled PVC compound for blow molded bottles.

In a recent interview with PLASTICS TECHNOLOGY, William F. Carroll, Jr., director of commercial development, discussed the company's progress in recycling and identified clear bottles, rather than pipe or construction materials, as the most economically promising application for recycled PVC in the 1990s. He also talked about the key role of processors in the post-consumer collection loop, and defended PVC against criticism that it hampers PET recycling efforts, pointing out that PET causes the same contamination problems for PVC recycling systems.

OVER 500,000 LB SO FAR

When OxyChem first announced plans to purchase PVC bottles from the municipal waste stream in September 1989 (see PT, Nov. '89, p. 93), it was considered a pioneering venture, as it was one of the first nationwide programs to collect and recycle post-consumer PVC waste. The program was intended to break down barriers to recycling PVC by providing a market for the material, according to Carroll.

OxyChem estimates it collected about 500,000 lb of PVC in 1990, and expects to collect 2.5 million lb more this year. Carroll pointed out that because PVC bottles represent only a fraction (about 5%) of the total plastic bottle waste stream, PVC recycling efforts would depend on being part of broader post-consumer collection programs.

Occidental's recycling strategy is to accept only post-consumer PVC bottles in minimum loads of 5000 lb (previously 2000 lb). Recyclers separating PVC are paid prices equivalent to PET (9 [cents]/lb), in addition to freight costs. OxyChem will then formulate the recycled PVC into bottle compounds.

The company has no plans to build its own recycling facilities for separation, washing and regrinding. Instead, Carroll said it will continue to use existing regional recycling facilities, many of which are interested in sorting PVC to help fill out excess capacity. For example, OxyChem recently agreed to work with the Plastics Recycling Alliance in Philadelphia to automatically sort PVC bottles from mixed consumer bottles at PRA's facility. PRA is a joint venture of Du Pont Co. and Waste Management, Inc., whose focus has up to now been on separating HDPE and PET bottles from mixed waste.

OxyChem has pursued technology for reprocessing and compounding recycled PVC through joint development with Wheaton Plastic Recycling Co., Millville, N.J., and another unnamed vinyl processor.

RECYCLED PVC FOR BOTTLES

OxyChem is developing an EcoVinyl line of recycle-containing compounds for blow molding containers to hold automotive fluids, household cleaners, and possibly shampoos. Carroll acknowledged it will be several years before a viable food-contact recycle grade of PVC is realized. The current version is a clear bottle grade containing a 10-25% recycled PVC and priced competitively with virgin PVC. Carroll said EcoVinyl is in the early development phase, with test quantities not yet available.

According to Carroll, built-in cost factors associated with reclamation procedures will keep recycled PVC out of highly price-sensitive markets such as pipe, siding and construction materials, leaving packaging as its most viable niche. Nevertheless, he said there are still hurdles to clear for this application--e.g., the uncertain quality of recycle-content compounds for clear bottles and the current scarcity of joint-development efforts between processors and resin suppliers. However, Carroll said factors such as anticipated recycle-content legislation, research to improve product properties, and the current cost structure of packaging compounds will serve to make recycled PVC attractive for bottle applications.

KEY ROLE FOR PROCESSORS

Processors have an important role to play in the recycling loop, according to Carroll. He said both processors and resin producers must "bring something to the party" in order to successfully process recycled materials. Carroll said two challenges requiring more cooperation between processors and resin producers are overcoming heat-history problems associated with recycled PVC and developing more efficient production methods and systems to minimize processors' internal scrap rates.

"Processors must realize that recycled resin will never equal virgin quality. It will take some finesse on their part to tweak the system to best use the material," according to Carroll. "As resin producers, we must get recycled resin quality to be as close as possible to virgin. Quality and purity are king when it comes to recycled resins. Everyone wants virgin quality at garbage price."

CROSS-CONTAMINATION DEBATE

There is an ongoing cross-contamination problem associated with the sortation of recycled PVC and PET. As the two types of clear containers are often difficult to distinguish in manual sorting operations, PVC is the bane of PET recyclers, and conversely, Carroll said PET was his "biggest problem" in maintaining the purity of recycled PVC.

The two resins pose contamination problems for each other, owing to their different melt temperatures. PVC burns and causes black specks in a PET system, while PET creates gels and clogs filter screens when remelting PVC.

OxyChem's research found that typical manual sortation in PVC recycling results in an average 5% error rate per hour, while the allowable rate of contamination is 0.05%. This gap in separation accuracy creates the need for more reliable, automated sortation systems.

The company supports a variety of automated PVC sortation systems for its program. The different automated systems have various levels of application, given the size and demands of the recycling operation. Three automated PVC sortation technologies cited by Carroll have been developed by Asoma Instruments Inc., Austin, Texas; National Recovery Technologies Inc., Nashville, Tenn.; and Tecoplast Govoni SpA, Casumaro, Italy (see PT, May '90, p. 31). All use x-ray fluorescence or other electromagnetic means to distinguish PVC from other polymers. Another method to assist in more accurate separation is cryogenic grinding, which produces a fine, uniform powder especially useful to dryblend users.

MORE IN PVC RECYCLING

Other programs aimed at PVC recycling include efforts by BFGoodrich Co., Cleveland, and the Vinyl Institute, Wayne, N.J. Fred Krause, director of Environmental Solutions for Goodrich, as well as the chairman of the Vinyl Institute's recycling committee, said the most pressing issue for PVC recycling involves development and application of reliable, automated methods for removing vinyl from the waste stream.

"Our applications for vinyl recycling take in a broader variety of materials than just post-consumer bottles," he said, speaking for the Vinyl Institute. "Right now we're concentrating on how to pull out all kinds of PVC from the waste stream through automated systems." He explained that automation is viewed as an economical means of separating the broad variety of PVC bottle sizes and shapes from a mixed waste stream, given vinyl's relatively small volume compared with other plastics.

One effort, sponsored by the Vinyl Institute, uses an automated system from National Recovery Technologies Inc., Nashville, Tenn., at a material recovery facility run by XL Corp. in Crestwood, Ill. The system, set to be operational early this year, is set up to demonstrate the viability of automatic detection and removal of PVC from a general waste stream. The system reportedly can scan 10 bottles/sec, or about 10 million lb/yr, as the bottles pass on a conveyor belt over electromagnetic detectors. If the presence of chlorine is sensed, air jets kick the PVC bottles into a separate bin. The system is said to be unaffected by bottle orientation, labels, caps, or basecups, and can detect a PVC bottle sandwiched between two non-vinyl bottles.

BFGoodrich has installed an Asoma x-ray fluorescence system at its Avon Lake, Ohio, recycling laboratory and technical center. The company has established a pilot operation in Akron, Ohio, in association with wTe Corp. of Bedford, Mass., to collect and sort post-consumer plastics. Most of the plastics will be used in recycling applications, with some designated as fuel for a waste-to-energy plant.

Another pilot program involves collection of PVC bottles in Waukesha County, Wis. Goodrich cleans and regrinds the bottles, and then delivers the material to Schoeneck Containers Inc., New Berlin, Wis., for blow molding into new containers. Krause pointed out the program with Schoeneck is still in the early experimental phase.

Krause said a new project at Goodrich will evaluate potential applications for recycling wire coatings, known as "fluff." Recovering PVC from this often highly mixed waste stream is considered a great challenge.

PHOTO : Occidental Chemical's PVC recycling efforts will target recycle-content resin grades for bottle applications. Its EcoVinyl line, now in the early development phase, may contain a recycled content up to 25%.
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Author:Gabriele, Michael C.
Publication:Plastics Technology
Date:Mar 1, 1991
Words:1412
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