Last week at the Association of Post-consumer Plastics Recyclers (APR) Technical Committee meeting, we had a major breakthrough for recycling. For years the PET bottle recycling stream, and often the HDPE stream, has been contaminated by silicone used in valves and liners of dispensing closure systems.
Recently Aptar, a major global closure manufacturer, learned of this issue. Since the silicone contamination is often caused by the closure valves and liners in items such as ketchup and mustard containers and swivel caps used in some sports drinks; Aptar searched for alternative materials that would not threaten the recycling stream but work equally as well in all applications. They are promoting a polyolefin based thermoplastic elastomer (TPE) replacement for silicone which will solve the problem.
We, at Envision, have experienced silicone contamination at least six times in our recycled resin production resulting in a $20,000 plus loss in revenue per event. We are extremely grateful for a solution. Even though silicone is primarily used in PET bottle applications as an ingredient in closures, many HDPE bales are speckled with PET bottles that have the silicone closures with them. So, if we miss sorting out the PET bottles prior to our grinding and washing; (although the PET we will sink out), the closure will float along with the silicon valve and liners.
Silicone is a thermoset resin. It will soften in our extrusion process, go through the screen pack and then reform into the original ground shape. Often at the HDPE bottle blow molder this ground silicone will go through their extruder, soften in the heat, go through their screen pack, resolidify, and create a hole where the piece of silicone contaminates the wall of the bottle, creating a hole. Just one ground valve or liner can cause 100’s of blow outs and create major production issues for our customers, causing them to shut down their system, purge out the recycled resin, and reject the silicone contaminated resin. We will never be able to remove the pieces of silicone once they are our HDPE recycled pellets, making them worthless to our customers.
Having a major closure manufacturer, such as Aptar, come up with an alternative that is no longer a contaminant, but can act as a compatabilizer, (such as TPE is known to be), is music to our ears. The PET recyclers must be even happier because they often see the silicone contamination in the floatable polyolefin’s that they try to sell. Let’s hope the Consumer Product Companies; which rely primarily on cost savings when evaluating component material changes, will yet embrace this new technology as a method to improve sustainability. Kudos to Aptar for creating this fix and bringing it to APR Technical Committee’s attention.