The Basics of Resin Drying

Dehumidifying of plastics resin is utilized to minimize or eliminate problems that may be caused by too much or too little moisture in a plastic material during processing. Although most processors accept the need to predry resins, particularly highly hygroscopic ones, many do not understand the basics - or even the vocabulary of resin drying.

The extent to which moisture affects the quality of a molded or extruded part is determined by the specific plastic resin being processed and the intended purpose of the part. Regardless, it is highly probable that improper or incomplete drying of the raw material will create problems, whether during processing or when the product is in use, or worse - both.

We use the topics below to help form a guide to understanding the basics of dehumidifying plastic materials as well as the esthetic and performance issues that present from improper drying.

How a dual bed desiccant dryer works
Above schematic shows how dual bed desiccant bed dryers work. This is an old technology that has been largely replaced by desiccant wheel dryers and membrane dryers.

There are many dryer types. Visit the Dryer Types section to see how many different drying methods are used for drying plastics resins.