1. Dyeing spandex with disperse dyes, the optimum process conditions are: temperature 125℃, time 30～40min, pH value 5～6.
2. The dyeing temperature should be controlled within the range of 120 to 130 °C. When the temperature is less than 120 °C, the color fastness is not enough, and it is easy to decolorize; when it is greater than 130 °C, the surface color depth and color fastness will decrease significantly, and the higher the dyeing temperature, the harder the spandex. The smaller the degree of hydrogen bonding between the segments, the lower the crystallinity of the hard segment, and the more serious the damage to its mechanical properties and structure.
3. The dyeing time is generally controlled at 30 minutes. The dyeing time is short, the dye molecules are poorly bonded to the spandex, and the color fastness and color depth cannot reach the standard. If it exceeds 30 minutes, the intermolecular slippage of the macromolecular chain or the chemical bond is severely broken. The degree of hydrogen bonding decreases and the crystallinity decreases, resulting in lower breaking strength and poor dyeing properties.
4. Spandex fiber has good acid resistance and poor alkali resistance. It shows good dyeing performance and less damage to the mechanical properties of spandex under the condition of weak acid with pH value of dye liquor equal to 5-6.
5. The dyeing properties were analyzed from the microstructure of spandex by FTIR and XRD test methods, and a comprehensive analysis was carried out with the hydrogen bonds of the groups to more clearly and accurately explain the influence of the dyeing process on spandex, which could ensure the best dyeing effect of spandex and the least damage .