Naphthol AS-BS

Naphthol AS-BS is a high-performance azo dye coupling component belonging to the Naphthol AS series. Chemically, it is identified as 2-Hydroxy-3-naphthylformyl-m-nitroaniline, a structure specifically designed to deliver strong coupling activity and distinctive shade characteristics. The product is supplied as a uniform yellowish-green powder with high chemical purity (≥98%) and a well-defined melting range of 246–247 °C, reflecting its stable molecular structure and suitability for controlled industrial applications. The presence of hydroxyl and amide functional groups within the molecule plays a critical role in its reactivity and final color development.

From a physicochemical standpoint, Naphthol AS-BS is practically insoluble in water but readily forms a soluble sodium salt in alkaline aqueous solutions. This behavior is essential for its use in azoic dyeing processes. It is also soluble in certain polar organic solvents, such as dimethylformamide (DMF), which supports its use in pigment synthesis and laboratory formulation work. The alkaline solubility allows the coupling component to be applied evenly to textile substrates, ensuring uniform distribution prior to color development.

In textile dyeing and printing, Naphthol AS-BS is mainly used on cellulose fibers such as cotton and viscose, and it also shows good affinity for certain regenerated and natural fibers, including silk. During application, the product is first dissolved in an alkaline bath to form the sodium salt, which is then absorbed by the fiber through padding or impregnation. After fixation, the treated fabric is developed with compatible diazonium salts. The coupling reaction takes place directly within the fiber matrix, generating insoluble azo pigments in situ. This internal pigment formation results in high-strength color lakes with vivid red-dominant shades, excellent depth, and good shade clarity.

Fabrics dyed with Naphthol AS-BS demonstrate very good fastness properties, including resistance to washing, rubbing (both dry and wet), and light exposure. These characteristics make it especially suitable for continuous pad-dyeing and printing processes used in high-end apparel fabrics, home textiles, and other products where durability and color brilliance are required.

Beyond textile applications, Naphthol AS-BS is an important intermediate for the synthesis of high-performance azo pigments. These pigments are widely used in inks, industrial coatings, and plastic coloration, where they contribute strong tinting strength, good dispersion behavior, and stable color performance.

From a safety and handling perspective, the product should be managed with standard industrial precautions. Fine dust may cause irritation to the respiratory tract, so appropriate personal protective equipment and adequate ventilation are recommended during handling and processing. Produced under controlled manufacturing conditions, our Naphthol AS-BS offers consistent quality, reliable performance, and suitability for both dyeing and pigment-related applications.

This product is mainly used as an intermediate for organic pigments, and can be used in the production of Pigment Red 18, 23, 31, 114, 157, and 212. It can also be used for dyeing cotton yarn, cotton fabrics, vinylon, viscose, and silk, as well as for discharge printing on cotton fabrics. It can be used to manufacture fast pigments, neutral pigments, and organic pigments. This product has a high affinity for cotton fabrics and a moderate coupling ability.