Why TPU needs to be dried?
TPU is an eco-friendly plastic stretch material, which is used in various fields. In the past, PVC is the main plastic material, but now TPU is playing a more and more important role. Since the governments realized that environmental-friendly was a significant part of sustainable development for economy, people’s live and even the whole world, choosing an eco-friendly material was one of the steps.
Although there is no evidence to prove that TPU actually does harm to the environment and people’s health, TPU is more difficult to be processed than PVC. Drying is one important process step which known to all whom involve in TPU industry.
But why TPU needs to be dried? It refers to the feature of TPU. Because of the special molecular structure, TPU granules can absorb moisture from the air. When the volume of absorbed moisture reaches to it’s critical point, the molecular structure of TPU granules would change and degrade into water. Therefore, raw TPU material should be sealed and stored in dry conditions.
Another reason is that the final TPU products would be affected by the moisture in TPU materials. Generally, TPU raw materials should be dried for 3 hours before processing to keep the moisture content lower than 0.02%. Otherwise, the final products would become defective goods. For example, if our TPU material hasn’t been dried enough, the TPU coated webbing would have bubbles or lines on surface. Moreover, the TPU webbing even has less tenacity.
Since TPU is difficult to process, drying is just the first step. For different product, TPU has its own different process difficulty. We believe that more technical problems can be solved with the developing technology.