Tri-n-butylphenyltin is primarily used as a stabilizer in the production of polyvinyl chloride (PVC) plastics. It helps prevent degradation of PVC when exposed to heat and light, ensuring the material maintains its integrity and performance over time. Additionally, it finds application in the manufacturing of coatings and adhesives, where it enhances durability and resistance to environmental factors. In some cases, it is also utilized in antifouling paints for marine vessels, preventing the growth of aquatic organisms on ship hulls. Its role in these industries highlights its importance in improving the longevity and efficiency of various materials and products.