Tri-p-tolyl phosphite is primarily used as a stabilizer and antioxidant in various polymer systems. It helps prevent the degradation of polymers caused by heat, light, and oxidation, thereby extending their lifespan and maintaining their mechanical properties. This chemical is particularly effective in polyolefins, such as polyethylene and polypropylene, where it enhances thermal stability during processing and end-use applications. Additionally, it is employed in the production of synthetic rubbers and elastomers to improve their resistance to aging and environmental stress. In the coatings industry, it serves as an additive to protect paints and varnishes from yellowing and deterioration due to exposure to oxygen and UV radiation. Its ability to act as a chelating agent also makes it useful in certain metal treatment processes, where it helps in stabilizing metal ions and preventing unwanted reactions.