If you’ve visited our news page before, you may have noticed numerous images of resin pellets and granules accompanying posts. This is because resin pellets are a key component in the manufacturing of products, and they factor significantly into plastics processing operations.
In this post, we thought we’d highlight exactly what resin pellets are, the types of resin that exist, the products that use plastic pellets, and more. Read on for insights.
About Resin Pellets
Plastic resin pellets are the raw form of the material needed for the production of a variety of plastic goods. Other names for this material include pre-production plastic and nurdles.
These pellets can be either disc shaped or barrel shaped, with their sizes ranging from 2mm to 5mm in most cases. Common types of resin pellets include:
- High-density polyethylene (HDPE) pellets
- Low-density polyethylene (LDP) pellets
- Linear low-density polyethylene (LLDPE) pellets
- Polypropylene (PP) pellets
- Polystyrene pellets
- Polyvinyl chloride (PVC and vinyl) pellets
- Polyethylene terephthalate (PET, PETE) pellets
The process of getting to the finalized resin pellets features a numbers of steps, so let’s look at each.
- A chemical engineer will prepare any raw materials and monomers needed to craft specific resins. This can include such materials as ethylene and propylene, both of which originate in crude oil.
- Within these materials are hydrocarbons, which go toward making up the monomers, and these need to go through a cracking process to obtain them. Once obtained, hydrocarbon monomers and other carbon monomers are then developed by the chemical engineer, resulting in materials such as vinyl chloride, styrene, and acrylonitrile, which are then utilized in plastics.
- The monomers that are produced during this process then create polymerization reactions, which in turn produce polymer resins. These resins are gathered and refined during further processing.
- During this refining, plasticizers, colors, and flame-resistant chemicals can all be added to improve the resins. The end result is a polymer resin that has been crafted into beads, or, more often, pellets.
Once a specific type of resin is crafted and selected, the material is then processed by melting it so it can then be molded into the end product desired.
How Resin Pellets Are Used in Manufacturing
Some of the more popular uses of resin pellets include the following:
- Injection molding – During the injection molding process, resin pellets are heated and then placed within a chamber for mixing. Through the use of high pressure, the melted mixture is then put within a cooled mold for further development of the end product.
- Extrusion – During the extrusion process, resin pellets are once again heated and then placed within a chamber. Following this, the material is put through a small opening for cooling by way of either water or air.
- Rotational molding – In this process, the pellets are heated and then cooled down within a mold that has the ability to be rotated three dimensionally. Because of the rotation, the plastic is distributed evenly within the mold, covering its walls. Oversized, hollow plastic items are often crafted by way of this process, including such products as children’s toys, sporting goods, trash cans, and more.
- Blow molding – Both injection and extrusion molding play a role with blow molding. During the process, the selected resin pellets are heated and then compressed within a liquid tube. Following this, the resin is placed within a cooled mold where compressed air is blown, which expands to the walls of the mold. One common application for this process is the creation of plastic bottles.
Industries and Products That Use Plastic Pellets
Virtually any industry which incorporates plastics processing into their operations may well utilize resin pellets at some stage, but some of the more common industries include:
- Personal care industry
Within these industries, there are a wide variety of products crafted by the diverse types of resin pellets, such as HDPE resins and PP resins. Some common products include:
- Milk containers
- Bottles for cleaning supplies
- Bottles for personal care items
- Fuel tanks
- Linings for truck beds
- Drums and buckets
- Grocery bags
- Car upholstery
- Home furnishing upholstery
- Plastic covers
Along with all these ways that resin pellets can be melted down and used in various applications, other applications involve utilizing raw resin pellets for bean bags and cornhole bags (from the popular party game) to serve as filler.
Resin Pellets and the Environment
Because of their small size, resin pellets can often be lost or accidentally spilled during processing or shipment. Some of these lost pellets can then find their way into waterways and the ocean, increasing the pollution problem and harming wildlife.