Now, the pressure on environmental protection is increasing. Nylon filaments promote cleaner production, and the water-free coloring process has attracted more and more attention. The following is some relevant knowledge of the waterless coloring process.
At present, the coloring of the polyamide filament in China's nylon industry is mostly used for dip dyeing and pad dyeing in the later stage of spinning. The dyes used include disperse dyes and acid dyes. This method is not only inseparable from water, but also has high energy consumption and high cost. The pollution of printing and dyeing wastewater in the later stage is very troublesome.
The pigment is used as a coloring agent to prepare a color masterbatch, which is melt-spun with nylon 6 yarn chips to obtain a nylon 6 yarn colored yarn. The entire spinning process does not require a drop of water, and it is green and environmentally friendly. It is a more applied process that has emerged in recent years, but it is not perfect in terms of spinnability and levelling properties.
The vacuum sublimation dye coloring process uses disperse dyes or easily sublimable pigments as colorants, which are sublimated into gas under higher temperature or vacuum conditions, adsorbed on the surface of nylon 6 yarn filaments and diffused into the fiber to complete the dyeing process.
This process does not consume water, but there are very few types of dyes and pigments that can be used to color nylon 6 yarn filaments. The control of the sublimation speed will affect the levelness and dye uptake to a certain extent, which requires high equipment. Although there is no problem of water pollution, the pollution to equipment, environment and operators cannot be ignored.
Supercritical carbon dioxide dyeing does not consume water. Hydrophobic disperse dyes can be dissolved in supercritical carbon dioxide to color nylon filaments. Compared with water dyeing, the dyeing time is shorter. Only by adjusting the pressure and temperature, the entire dyeing process can be completed on one device, but it cannot effectively solve the effect of oligomers on the dyeing performance during the dyeing process.