Diphenyl phthalate is primarily used as a plasticizer in the manufacturing of various polymers, particularly in the production of flexible PVC products. It enhances the flexibility, durability, and workability of plastics, making it suitable for applications such as cables, flooring, and synthetic leather. Additionally, it finds use in the formulation of adhesives and coatings, where it improves the performance and stability of the final product. Its role in the cosmetics industry includes acting as a solvent or fixative in fragrances, ensuring longer-lasting scent profiles. In the pharmaceutical sector, it is utilized as an excipient in certain drug formulations to control the release rate of active ingredients. Its versatility also extends to being a component in specialty chemicals and industrial applications where plasticizing properties are required.