Used plastics are versatile and adaptable, as illustrated by their wide range of uses. There is a large market for recycled plastic containers like butter tubs, and keeping that valuable material out of landfills helps reduce energy use and emissions.
Collected at curbside or drop-off locations.
A butter tub that is made from high density polyethylene (HDPE) has specific properties that are different from other plastics. So as the butter tub goes through the materials recovery facility (MRF), it passes by an infrared optical sorter. The sorter identifies the butter tub as a certain kind of plastic (HDPE) and a jet of air separates it from the other plastics.
All the HDPE bottles are baled together and sold to a plastic reclaimer for processing.
The plastic bottles are ground into small chips of plastic called flake. This flake is then washed, and any dirt or non-HDPE plastic is separated from the HDPE. One way different types of plastic are separated relates to their density. When put in water the lighter-weight plastic (such as HDPE) floats and the heavier plastic sinks. Once separated, the flake is dried.
Now that the plastic flake has been washed and separated, it may be melted and extruded through a die, then cut into a pellet. This allows for a uniform raw material to be put back into a new product.
Through a process called blow molding, the pellet can be used by manufacturers to make new butter tubs. First, the pellet is melted, and then formed into a parison (a hollow, tube-shaped blob of melted plastic). The parison is clamped into the tub mold and air is pumped into it. The air pressure pushes the plastic out into the mold. Once the plastic has cooled and hardened, the mold opens and the new tub is ejected.