Isopentyl pentyl phthalate is primarily used as a plasticizer in the production of flexible polyvinyl chloride (PVC) products. It enhances the flexibility, durability, and workability of PVC, making it suitable for applications such as cables, flooring, and synthetic leather. Its compatibility with PVC and ability to improve material properties make it valuable in industries requiring resilient and adaptable materials. Additionally, it is sometimes utilized in coatings and adhesives to improve performance characteristics.