How Plastic Lumber is Made
Plastic lumber is becoming a popular green building material. This product is made from recycled plastics. But, many individuals do not know how this amazing building product is made. Hopefully this article will take the mystery out of how plastic lumber is made.
Many of us wonder what happens to that empty plastic milk jug or other plastic containers that are tossed into the recycling bin. This milk jug is on a journey to the recycling plant where it will soon become a recycled product such as plastic lumber. The reason why milk jugs are used is because they are a number 2 recyclable plastic materials. This type of plastic is a high-density polyethylene that is used to make plastic lumber.
Once the plastic has been shredded it is then moved to a hopper where it will then go to an extruder. The extruder then heats the high-density plastic to about 425 degrees. The plastic is heated thoroughly until it is about the consistency of firm dough. This product then is pushed through a dye to give it the shape of a board. As the plastic moves through the dye it rises much like yeast bread when it hits the cooler air outside of the extruder. As it moves out of the extruder it is then quickly put into a cooling tank. What this cooling tank does, is stops the rising process immediately. The cooling tank is filled with thousands of jets that shoot ice-cold water on the plastic to stop this process. This also cools the outside layer of the plastic to room tempeture.
After the cooling process is completed the plastic lumber makes its way down a conveyor belt to start and air dry process. This helps all of the water to dry that is on the surface of the plastic. The air-dried plastic is then ran through another cooling tank before it makes its way to an embossing machine. The embossing machine heats up the surface of the plastic lumber to about 300 degrees before it is ran through. This makes the top of the lumber soft enough to then be stamped with a wood grain pattern. The plastic lumber is now sent to a cutter where the boards are then cut to specific lengths and are then ready to be shipped off to the construction site.
Plastic milk jugs have found a new life by being turned into plastic lumber. So, the next time a plastic milk jug is sent through the recycling process, it may become a new deck, or a new bench at the local park and finds new life as plastic lumber.