In previous blogs, we have explained how PVC resins are created and how they are combined with stabilizers, plasticizers and other ingredients to create PVC compounds. Once a compound is formulated, and the product is properly dry blended, and melt mixed, the next step is to create pellets to deliver the material to processors for use in their production process.
Pellets can be produced with different sizes and shapes. Some typical forms are, for example: oval, cylindrical, cubic or hexagonal cut. The selected pelletization process must be well controlled to minimize or prevent the production of fine plastic shavings, and irregular shaped or clumped pellets. This is needed to ensure that the pellets provide consistent flow through customer bulk conveying equipment, unrestricted feeding in hoppers above customer processes, and that they melt uniformly, and without defect. Various compound processing methods can be used to produce the different pellet types, and each can also change the melting and processing behavior of rigid and flexible PVC compounds. Ultimately, the pelletization method selected is dictated by the properties of the specific formulation of the compound supplied, and any requirements of the customer’s process.
As the compound production process is completed, pellets are packed into gaylord containers and transported to manufacturers around the world - where they will be fed into machines which create the components and products we all use every day.
Any changes in the compound processing conditions can potentially change the way specific pellets process during production. Two pellets, with the exact same formulation, but cut differently, may give a completely different outcome when run on the exact same machine. Likewise, a pellet that runs well on one machine won’t necessarily run well on a similar machine if that machine has significantly different configuration.
It takes years of technical and processing experience, as well as acute attention to detail, to produce the right pellet cut for each processing environment and application, and to be able to replicate the same, consistent results in cut and formulation each time a batch is created. Failure to keep all aspects of a compound and the process it goes through consistent could result in significant problems on the production line. This is yet another reason it is imperative for manufacturer’s to do their due diligence when partnering with a compounder.
Some compounders create a PVC compound to sell to customers. Teknor Apex partners with customers to create PVC compounds that help them create their products.
Contact the Vinyl Division to discuss how we can assist you with your custom compounding needs!
