The 3D printing filament company Polymaker is working with Covestro to manufacture Polymaker PC-r, a recycled polycarbonate. The polycarbonate comes from huge 19-liter bottles from Nongfu Spring. These bottles are used repeatedly for home and office water all over China. Covestro started a project in 2020 to work with Nongfu to recycle one million of the water bottles a year.
New material is sometimes required to manufacture new filament, but most of it comes from recycled bottles. The resulting material in turn bears the “Blue Angel and EPEAT seal”.
Covestro: “It is an advantage that the waste comes from a single source. This means that no prior sorting and identification of the plastics is necessary. The plastic waste is quite pure and can be recycled inexpensively. It is also available in sufficient quantities. In China, large-volume water bottles are widely used in homes and public places. These are collected and refilled over and over again before they are finally disposed of and recycled. “
Compared to single-use plastic bottles, this is much more sustainable. There is one more benefit to this: the MFI (Melt Flow Index) is known and constant, which means it is easier to mix the material, extrude it into filaments, and print it. The collection of these bottles is also known and easy, as this work is often done by partners when changing bottles and you don’t have to fish them out of the garbage.
Covestro also says that in order to print the polycarbonate well without distortion, constant chamber temperatures are necessary. This was tested on a FUNMAT PRO 410 from INTAMSYS. In this way, “the test results show good values for tensile strength, Young’s modulus, flexural strength and flexural modulus, which were slightly higher than for standard polycarbonate.”
This is a fine example of how companies work together to develop circular practices. I am usually extremely cautious about projects and announcements like this. There is a lot of greenwash and excessive demands in this area. In this case, it seems like a solid implementation that is realistic too. By working with a traceable container whose life and condition can be approximated, and by working with a substance whose values are known, it is much easier to do something like this well.
By working directly with the water supplier, future bottle designs can be optimized for recycling, for example by using a different adhesive for labels or by doing without it altogether. The removal of rings and caps can also be optimized. In this case, there is also a small chance that the polymer will be contaminated or degraded beyond its useful life. You will know exactly when the bottle was made, how long it was used and for how many cycles it was used. When it comes to post-consumer waste, there is usually concern about what substances the polymer came into contact with or how it was previously treated. This approach avoids all of this.
If you go further, Covestro could see itself as the guardian of this material and, for example, plan its traceable use over eight cycles as a consumer water bottle and then plan a double recycling stop as an entertainment electronics housing before turning it into a 3D printing material. If a QR code could then always identify the material, when it was manufactured and what additives it contains, then it could be managed for years. Instead of throwing some granules over the fence, Covestro would manage a polymer in the most sustainable and expedient way for decades. I welcome things like that and think we should have a lot more initiatives like this one.