Why does TPU turn yellow?

TPU is a polymer material which is made of diphenylmethane diisocyanate (MDI) or toluene diisocyanate (TDI) and other diisocyanate molecules, macromolecular polyols and low-molecular polyols (chain extender). Diphenylmethane diisocyanate (MDI) or toluene diisocyanate (TDI), which are the main raw materials of synthetic polyurethane materials, will turn yellow under ultraviolet radiation, so yellowing is an attribute of TPU.

How to prevent TPU yellowing?

Since TPU is a kind of resin that is easy to yellowing, yellowing is an unavoidable problem for TPU materials. How to prevent or delay the yellowing of TPU is the problem we have to face. To prevent yellowing of TPU material, without the limitation of cost, the preferred material must be Aliphatic Polyurethane (Aliphatic Polyurethane) TPU. Aliphatic polyurethane has excellent chemical resistance and excellent aging resistance and is suitable for prolonged use under harsh conditions. If the cost factor is considered, we will choose the non-aliphatic economic TPU material with anti-aging agent. It is just a matter of time before TPU yellowing with anti-aging agents is added. Therefore, we need to find ways to delay the yellowing time of TPU.

How to delay the time of TPU yellowing?

1. TPU materials should be stored in a cool and ventilated place without sunlight exposure. 2. Add anti-aging agent (anti-yellowing).3. Spray anti-yellowing paint on the surface of TPU products. Spray application of anti-yellowing paint will form a protective layer on the surface of TPU products to avoid yellowing of TPU surface in contact with the atmosphere. 4. Avoid pollution during manual operation. Many TPU finished products are contaminated in the process of finishing or rescue, resulting in yellowing, such as human sweat and organic solvents. Therefore, TPU products should pay special attention to the cleanness of the contact body, and minimize the finishing process.

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