Post-consumer plastics have potential in automotive applications, but they also have challenges

Buckeye Polymers logoWhen it comes to using post-consumer feed stock as opposed to post-industrial feed stock for automotive parts, there appear to be pros and cons for each option. But opportunities for using post-consumer resins (PCR) do exist, if the challenges of this recycled material obtained from PCR streams can be overcome, said Mike Montpetit, National Automotive Sales and Engineering Manager for Buckeye Polymers (Lodi, OH).  That was the theme of his presentation at the Plastics-in-Motion conference in Charlotte, NC, earlier this month titled, Automotive Applications for Post-Consumer Plastics.

Montpetit compared post-consumer with post-industrial recycled resins, noting their advantages and disadvantages. PCR feed stock generally is always available from material recovery facilities (MRFs) and is not subject to economic conditions to the extent of post-industrial resins. Also, it is typically not tied to virgin resin pricing. MRF-dependent PCRs have a narrow window of melt flow ranges, as well as other physical and mechanical properties.

PCR feed stock also contains less than 2% filler, used to color the original product, such as a yogurt tub. “In the post-consumer arena, the problem is color,” Montpetit told PlasticsToday. “The FDA approves resins for food-use, then color concentrates are added to them, usually less than 2%. It’s easier to get the same material every time when dealing with post-consumer feedstock.”

Post-industrial recycled resins also have pros and cons: They are not always available; are subject to economic conditions; have a price point just under that of virgin resin; and offer a wide window of melt flow ranges (5-50 MFI) and filler ranges (5-40% talc, calcium, glass).   

Montpetit noted that Buckeye Polymers cannot use PCR resins as they come from the MRFs, which are #3 through #7 bales. The company qualifies the material coming from the MRFs; 82 MRFs process between 50 million and 400 million pounds each year of multi-stream plastic waste. Of those, 50 MRFs have at least one optical sorter to collect polypropylene (PP). The company identified those facilities producing a post-consumer bale with #1 PET and #2 FRAC HDPE removed, resulting in the 3-7 rigid plastic bale.

It then identified facilities producing a high-percentage PP bale. Bales must contain less than 10% contaminants such as paper, wood, metals, bags and so forth. Buckeye Polymers physically viewed the MRF process, qualifying the bales visually, and purchased 40,000 pound loads for evaluation. These loads then underwent manual sorting, size reduction, aspiration, sink/float processing, washing and drying.

“Our job is to harvest the bales that come from the recycler, refine them to get out the PP, then blend it with various impact modifiers to raise the impact resistance,” Montpetit explained. “We have several refining steps we put the bales through to harvest the PP.”

More testing was done by taking 20 5-lb. samples of finished flake pulled from across three 40,000-lb. production lots. “We need to be confident that the physical properties—MFI, ash, moisture, notches Izod and flexural modulus—were consistent for each qualified MRF.

Production processes were monitored by load arriving from each MRF. Fallout (non-olefinic) portions were tracked during the sorting and aspiration processes, as well as during the sink/float process. Initial loads with at least 50% recoverable content that processed within a three-shift window were advanced into a second trial period, repeating the process until a clear, consistent set of data developed.

To better understand where it can consistently obtain the best feed stock,  Buckeye Polymers mines data based on what people eat in a given region to ensure that it knows the type of polymer recyclate it will get from the various MRFs. “People in a region tend to eat the same thing, so we are able to measure that and get an idea of the consistency of the resultant harvested product,” said Montpetit.

The PCR has to be blended with wide-spec material or post-industrial feed stock, depending on what’s available, to provide Buckeye Polymers with the physical and mechanical properties needed to achieve the part performance characteristics required by its customers. 

Getting the PCR PP material that Buckeye Polymers requires for its formulation is not easy. Montpetit said that MRFs have been slow to invest in optical sorters for several reasons. “First is cost. A $750,000 investment requires at least 60,000 tons of throughput to recapture 45 to 50% PP,” he said. “Second is a lack of demand, as the bales still require processing to remove roughly 50% unwanted material that gets co-mingled during processing baled trash, which means the consumer of the bales must have a robust process in place.”

Municipalities also have not yet been able to “connect the dots” to the end users. Smaller MRFs still find it more cost effective to landfill plastics. However, new technologies are available to sort the polyethylene from the PP with purities greater than 98%.

“Currently we manufacture seven to eight million pounds annually of 60% post-consumer recyclate for automotive customers,” said Montpetit, adding that these resins are used for functional black plastic automotive parts such as wheel house liners and underbelly pans. “Mining PP from the PCR waste stream provides us with a consistent, cost-effective precursor material for automotive as well as consumer goods applications,” added Montpetit.

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