Repro HDPE Pellets
Recycled HDPE pellets are HDPE pellets made from reprocessing scrap HDPE. Recycled HDPE pellets are of a similar quality to virgin HDPE pellets in terms of chemical and physical integrity, though there are restrictions on scrap HDPE products being used to package foodstuffs. There is also some risk of contamination or structural weakness due to poor handling that should be kept in mind when looking for a reliable supplier of quality repro HDPE pellets.
The bulk of scrap HDPE comes in the form of post consumer HDPE. Post consumer HDPE products are those HDPE products which have been manufactured for use in consumer applications, such as milk bottles, shampoo bottles, and other kinds of household receptacles. These products are used for their intended purpose, then reclaimed from recycling programs. Other scrap HDPE is reclaimed from industrial sources, coming in the form of plastic drums, or off cuts and rejected malformed HDPE products from consumer production lines.
As a result of the various sources of scrap HDPE, the quality and appearance of various types of recycled HDPE pellets is also varied. Some recycled HDPE pellets may be clear and translucent in color, originating from well sorted post consumer HDPE scrap. In other cases, the recycled HDPE pellets may have a raw grey color, or dye may be added to the mix to create a homogeneous coloration. It should be noted that color alone does not reflect grade or quality of recycled HDPE pellets, though translucent recycled HDPE is generally regarded as being a safer bet, and lends itself better to applications where asthetics are important.
Producing Recycled HDPE Pellets
Recycled HDPE pellets start life as HDPE scrap. The scrap must be washed and sorted, then shredded and washed again. Various processes are then undertaken to ensure that the shredded HDPE is clear of the bulk of contaminants such as dirt, metals, and foreign plastics. This is the first part of perhaps the most important stage of HDPE recycling, as contamination can make a batch of HDPE effectively useless.
Shredded HDPE, or HDPE regrind as it is sometimes known, is then sent into a heating and extrusion chamber. This is a long barrel shaped device with a screw running down the length of it. The barrel is heated, and as the HDPE is carried through the chamber by the screw, it melts down into liquid HDPE.
Filters contained in the chamber catch any remnants of contaminants in a process called melt filtration. Good melt filtration is essential to the production of high quality recycled HDPE pellets. Though the bulk of contaminants are removed prior to melting, the smallest contaminant particles inevitably pass through the initial cleaning and filtering stages, and are only removed during the melt filtration process.
Due to its molecular structure, if heated to the correct temperature, HDPE can be melted down and reformed into new products many times with negligible loss of structural integrity, however the melting process must be carefully monitored to ensure that the HDPE stays within the correct temperature range so that it does not solidify prematurely, or become overheated and start to break down.
At the end of the chamber is a die through which the liquid HDPE is extruded. A blade slices the tubes of liquid HDPE into pellets, which are then cooled. This can be achieved by either extruding the pellets under water, or having the pellets drop into a water bath, occasionally circulated air is used to cool the pellets, but this is generally a slow and cost ineffective practice.
Grades of Repro HDPE Pellets
Recycled HDPE pellets come in all grades. It is possible to purchase injection molding grade recycled HDPE pellets, blow molding grade recycled HDPE pellets, pipe grade HDPE pellets, the list goes on.
When ‘grades’ are referred to, what is really being spoken about is the MFI, or Melt Flow Index. Melt flow index is a measure of how viscous HDPE is when melted, and is related to the molecular density of the HDPE. Very dense HDPE has a low MFI, and becomes thick and slow flowing when melted. This type of HDPE is suitable for blow molding applications. Conversely, HDPE with a high MFI becomes very runny when melted, and is more suitable for applications such as injection molding.
Repro HDPE Suppliers
We source reprocessed HDPE pellets from several suppliers world wide. Let us know your detailed requirements and we will get back to you with current offers and HDPE price quote