Aliphatic series TPU

Aliphatic TPUs are a specific type of thermoplastic polyurethane that exhibit high UV resistance, making them suitable for outdoor applications where prolonged exposure to sunlight is a concern.
According to the chemical properties of diisocyanate lipid components, TPU can be divided into aromatic and aliphatic groups. Aromatic is the most common TPU we use (not resistant to yellowing or yellowing effect is poor, not food grade), aliphatic is generally to do more high-end products. Examples include medical devices, materials that require permanent yellowing resistance, and so on.
Aliphatic also divided into polyester/polyether。
Classification of yellowing resistance: It is generally compared with gray card, divided into 1-5 levels. After yellow stain resistance test such as Suntest, QUV or other sun exposure test, compare the color change of the sample before and after the test, the best grade is 5, which means basically no color change. 3 The following are obvious discoloration. In general, 4-5, that is, slightly discoloration, has met most TPU applications. If you need no discoloration at all, you generally need to use aliphatic TPU, that is, the so-called non-yellowing TPU, the substrate is non-MDI, generally HDI or H12MDI, etc., and the long-term UV test will not discoloration.