Using an N-vinylpyrrolidone co-polymer in reactive dye printing as an alternative to urea

A series of water-soluble co-polymer (NS) from N-vinylpyrrolidone (NVP) and sodium p-styrenesulfonate (SSS) with a low molecular weight are synthesized as substitutes for urea in the reactive printing of cotton fabrics. The effects of the monomer ratio of NVP to SSS on the color yield of the printed fabrics, the color fastness, and the solubility of the reactive dyes were investigated. The possibility of using a flocculation treatment for printing wastewater was also evaluated. When the dosage of NS-02 (NVP:SSS=7:3) in the printing paste is 1.0 wt%, the color yield and the color fastness of the printed fabric are equivalent to or better than those obtained with 3.0 wt% urea. Compared with the traditional reactive printing with urea, the total nitrogen content in the wastewater after NS-02 is reduced to 15% of that using urea when treated with a suitable amount of inorganic flocculants. It meets the national discharge requirements for printing and dyeing wastewater. The study shows that a low-molecular-weight co-polymer (NS-02) has a high potential to replace urea for the printing of cotton fabric with reactive dyes.