Clean production of polyester fabric inkjet printing process without fabric pretreatment and soaping

We report an improved printing ink of polyester fabric employed in the production process of inkjet printing. In the design of printing ink, the solubility parameters of reagent and HLB value of surfactant are used to prepare the ink. This production process does not require the pretreatment of polyester fabric to directly carry out inkjet printing. By regulating the intermolecular force relationship between the components of ink and the compactness of ink microstructure, it can improve the diffusion of ink on the surface of polyester fabric. The low-field NMR (LF-NMR) revealed the correlation between the fluidity and transverse relaxation time of main reagent solutions and ink. The test results show that there are three types of water: hydrogen-bond water, bound water and free water in main reagent solutions and ink. The LF-NMR was also used to investigate the relationship between ink viscosity and transverse relaxation time. It was observed that the transverse relaxation time (1084.4–410.3 m s, peak maximum time of T22) of ink decreases with the increase of ink viscosity (2.3–11.1 mPa s). The viscosity and transverse relaxation time of ink is associated with the intermolecular force and the compactness of microstructure of ink. The formation of ink droplets was systematically observed by the ink droplet observation instrument. When the surface tension and viscosity of ink are 32.2–37.4 mN/m and 2.3–8.8 mPa s, respectively, the ink can be smoothly inkjet. With the increase of viscosity of the ink (2.3–8.8 mPa s), the sharpness of printing pattern is obviously improved, and the change rate of the line width (W) of the printing pattern is reduced from 52.6% to 4.4%. The microstructure of ink can bound the solvent of the ink, reduce the fluidity of the solvent, and improve the sharpness of the printing pattern. The test results of KES style and color fastness of the printed fabric show that the printed fabric fully meets the wearing requirements. Compared with other the soap liquid of printed fabric, the soap liquid of printed fabric RD-2B has strong UV absorption strength, the soap liquid RD-2B has a higher dye content. The characterization results of volatile organic compounds (VOC) in ink SDS R7 is 17.0 g/kg. The chemical oxygen demand (COD) values of printed fabrics RD-2B and SDS R7 are 150.0 and 102.0 mg/L, and the biochemical oxygen demand (BOD5) values of printed fabrics RD-2B and SDS R7 are 130.0 and 97.7 mg/L. Compared with the common polyester fabric printing ink (ink RD-2B), the prepared ink has the characteristics of environmental protection, high production efficiency and low energy consumption, which has the potential to achieve green printing.