Phthalic acid di-n-hexyl ester is primarily used as a plasticizer in the production of flexible polyvinyl chloride (PVC) products. It enhances the flexibility, durability, and workability of PVC materials, making it suitable for applications such as cables, hoses, and flooring. Additionally, it is employed in the manufacturing of coatings and adhesives, where it improves film formation and adhesion properties. Its compatibility with various polymers also makes it useful in the formulation of inks and sealants, contributing to their performance and stability.