1,5-Naphthalenediamine is primarily used in the production of dyes and pigments, particularly for textiles and plastics. It serves as a key intermediate in synthesizing azo dyes, which are known for their vibrant colors and strong bonding properties. Additionally, it is utilized in the manufacture of optical brighteners, enhancing the whiteness and brightness of materials like paper and fabrics. In the field of polymer chemistry, it is employed as a cross-linking agent to improve the durability and thermal stability of certain resins. Its applications also extend to research and development, where it is used as a building block for creating complex organic compounds.