Most people do not know that silicone rubber can be recycled. As it is often thrown away as waste, silicone rubber that is no longer useful is often referred to as “silicone rubber scrap”. By definition, scrap is a small piece or amount of something, especially one that is left over after the greater part has been used. We should not associate the word “scrap” with “waste” or “trash”. To us, silicone rubber scrap is a valuable resource.
At ECO USA, we’re trying to make a difference in the recycling industry and the world by researching and developing new technologies to recycle silicone rubber scrap. In 2018, silicone was estimated to be a 14.17 billion dollar industry and expected to continue growing at a compound annual rate of 4.5% through 2025. With that being said, with an increasing amount of silicone rubber and liquid produced annually, an effective process must be in place to recycle this material stream.
We have come a long way in developing our silicone recycling technology at our pilot facility in West Virginia. Our facility is capable of recycling all sorts silicone rubber and fluids into silicone oil or polydimethylsiloxane (PDMS), a fundamental form of silicone used in numerous applications across many industries. Currently, we collect silicone rubber scrap primarily from post-industrial sources. The scrap we collect are usually left-over, excess materials from an extrusion / injection molding process.
In a factory producing silicone products such as a silicone medical part, liquid silicone rubber is injected into a mold. The mold is a hollow metal block where the cavity is in the shape of the product. When the liquid silicone rubber is squeezed inside, it hardens into the shape of the mold and the product is ejected. Look at the picture above. As the liquid silicone is pushed inside, it must first make its way into the mold cavity. The silicone rubber forms along this path and ends up becoming a part of the finished product. Sometimes there are multiple pieces within a mold paths connect each of the pieces in a series. When the part(s) are ejected, the path or sometimes referred to as “runners” are clipped off and become silicone rubber scrap material.
Silicone rubber scrap can also accumulate as cut-offs or trimmings. For example, silicone rubber is often manufactured into thin sheets as rolls. The extrusion process for making silicone rolls requires the two sides of the rolls to be trimmed. This ensures the rolls are evenly sized. As there are no addition use for the trimmings, they are a great form of silicone rubber scrap for recycling.
The silicone sheets can be used directly as mats or can be further manufactured into silicone rubber stoppers. To manufacture rubber stoppers or a similar product, silicone rubber sheets are fed into a machine where stoppers are punched out. This process is similar to how a paper hole punch works. As you can imagine, this process leaves behind quite a bit silicone rubber scrap. See picture below.
At ECO USA, we collect all sort of silicone rubber scrap for recycling in the United States. We ask silicone rubber molders and manufacturers of silicone products to hold onto their excess silicone materials and send them to us for recycling. We also collect irregular, obsolete, or rejected parts and products. Contact us for more information about our free plant analysis and pick-up services.
In addition to silicone rubber scrap, we also collect expired and surplus liquid silicone rubber (LSR). This stream of material is generated when LSR material is vacuumed into the injection molding machine. As liquid silicone rubber is very sticky, there are always left over silicone materials stuck to the lining of the bags or drums holding the LSR. This material is valuable to us and we encourage manufacturers to send this liquid silicone material stream along with your silicone rubber scrap.
If you want to learn more about how silicone rubber can be recycled into silicone oil, check out our silicone rubber recycling process overview.