Who wants plastic scrap? Recycling and the issue of material compatibility: Page 2 of 3

By: 
December 15, 2015
  • attitudes;
  • The absence of a reliable index for postconsumer scrap.

Morales said that postconsumer recyclate quality has "improved tremendously." So far in 2015, the company has had only 10 serious complaints, which is "way down," and the company meets all regulatory requirements. In 2014, KY Plastics received "expanded approval" from the U.S. Food and Drug Administration's Center of Food Safety and Applied Nutrition for KWR621 FDA, a food-grade PP. The material has been approved for levels up to 100% recycled content.

"With an increase in capacity, we should see an increase in recycling, as materials will continue to be diverted from the landfill, even as the delta is a lot smaller between virgin and postconsumer recyclate," said Morales. "There has to be green in green efforts, or it won't work. It takes a lot of green to stay in the black."

Reducing the costs and carbon footprint of recycling would seem to be insurmountable challenges, but there are answers on the horizon. Would recycling be more cost effective if there was a way to eliminate the sorting and recycle co-mingled plastics? Salvatore Monte, president of Kenrich Petrochemicals Inc. ( Bayonne, NJ) , agrees that recycling could be made easier and more cost effective if there was a methodology of compatibilizing resins.

"Why is only 9% of plastics recycled from the municipal solid waste stream?" Monte asked. "Why can't Walmart reach 25% PCR content sustainability goals in blowmolded HDPE soap bottled on store shelves? Because PCR = 1+2+3+4+5+6+7 and these do not add up, as most polymers are incompatible with each other."

Monte explained that "conventional polymer compatibilization and recycled plastic centers around equipment that sorts, cleans, demagnetizes, washes, granulates, bales or melt processes recyclate. There are polymer compatibilitzers based on maleic anhydride chemistry, or bipolar thermoplastics that have affinity for two select recycled polymer streams. But currently, there's no one size fits all that will compatibilize resins," he told the audience at the Global Plastics Summit. "We may, however, have the answer."

Kenrich has developed a new titanium-mixed metal catalyst that has been shown to create in the compounding melt not alloys, but new, complex co-polymers having much higher mechanical properties, "which portends the achievement of high loadings of postconsumer recyclate in virgin polymers to meet sustainability mandates in consumer plastic packaging."

Monte said that it can be shown that 1.5% by total polymer weight of a new single-site titanium/mixed metal catalyst masterbatch in 40% active pellet (and 0.75% in 80% active powder form) produces compatible PCR plastic mixtures in the extruder melt--and acts as a compatibilizer for dissimilar polymers.

HDPE, PP and LDPE are olefins or "addition polymers," while PETE is an ester--a condensation polymer.

But, says Monte, "although PP and HDPE are both considered olefins, HDPE cannot accept more than 5% PP without creating incompatibility issues such as delamination during injection molding. The use of minor amounts of subject additives allow 50/50 blends of HDPE/PP to mold better and give stronger parts than HDPE alone."

His additives make the materials compatible.

Kenrich's chemistry appears to be gaining ground as it

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