Question: Are heat shrinkable sleeves UV resistant?
Answer: This question is incredibly common. The simple answer is "Yes. Covalence (formerly Raychem) Heat Shrinkable Products have excellent UV resistance".
The slightly longer answer is: Carbon black is one of the many components that are combined to manufacture the heat shrinkable HDPE backing of the Covalence shrink sleeves. Carbon black has long been known as a UV stabilizer, and has been used for years and years as a component in the jackets of the overhead wires that you see just about anytime you take a step outside.
These same overhead wires have been coated with Raychem shrink sleeves (complete with carbon black) for many years with no noticeable UV degradation. If Raychem sleeves were being destroyed by UV and falling from power and telecommunications lines, we would know about it. It simply hasn't happened. What better proof of UV resistance than decades spent in direct sunlight?