Discussion on the one-bath production process of color-fixing and anti-ultraviolet

1. Reactive dye mass fraction

The polyester-cotton fabrics were dyed with disperse golden yellow/reactive yellow, disperse blue/reactive blue and disperse red/reactive red respectively. Disperse dye 1% (omf), NaCl 30g/L, 130℃ for 40min, the effect of neutral fixation reactive dye mass fraction on K/S value and UPF value of dyed fabric.

It can be seen that with the increase of the mass fraction of neutral fixation reactive dyes, the K/S values of the three color fabrics all showed an upward trend. When the mass fraction of reactive dyes is greater than 3% (omf), the K/S values of red and blue fabrics tend to be stable.

When the amount of disperse dye is the same, the UPF value of the three-color fabric tends to increase as a whole, that is, with the increase of the neutral fixing reactive dye mass fraction, the UV resistance of the fabric is enhanced. This is because the dye has a certain anti-ultraviolet performance. With the increase of the amount of neutral fixing reactive dye, the anti-ultraviolet performance of the dyed fabric increases. In summary, the mass fraction of neutral fixation reactive dyes was selected to be 3% (omf).

2. Mass fraction of disperse dyes

Neutral fixation reactive dye 3% (omf), NaCI 30g/L, 130 ℃ for 40 min, the effect of disperse dye mass fraction on K/S value and UPF value of fabric.

It can be seen that with the increase of the mass fraction of disperse dyes, the K/S values of the three-color fabrics gradually increased, and after the dye mass fraction reached 2% (omf), the K/S values of the three-color fabrics gradually tended to be stable. When the dye uptake reaches saturation. It can be seen that with the increase of the mass fraction of disperse dyes, the UPF values of the three-color fabrics do not change much. Therefore, the test chooses the mass fraction of disperse dye as 1% (omf).

3. UV absorber mass fraction

Disperse dye 1% (omf), neutral fixative reactive dye 3% (omf), NaCI 30g/L, 130 ℃ for 40 min, the effect of UV absorber HLF mass fraction on K/S value and UPF value of fabric.

It can be seen that the K/S value of the fabric decreases with the increase of the mass fraction of UV absorber HLF. This is because HLF is a disperse UV absorber, and the adsorption of polyester-cotton fabrics is similar to the process of dyeing fibers with disperse dyes, and it will compete with disperse dyes during use. It can be seen that with the increase of the mass fraction of UV absorber HLF, the UPF value of dyed polyester-cotton fabrics shows a steady upward trend. The mass fraction of UV absorber HLF is selected to be 5% to 10% (omf).

4. Sodium chloride mass concentration

Disperse dye 1% (omf), neutral fixing reactive dye 3% (omf), UV absorber HLF 10% (omf), 130 ℃ for 40 min, the effect of NaCl mass concentration on K/S value and UPF value of fabric .

Adding sodium chloride to the dye bath can promote the dyeing of cotton fibers with reactive dyes, improve the dyeing rate of reactive dyes, and increase the dye content on the fabric. However, the excessive amount of sodium chloride will cause the aggregation of disperse dyes in the solution, reduce the dyeing rate, leveling and dyeing effects, and even cause dye precipitation.

It can be seen that after the mass concentration of added sodium chloride reaches 20g/L, the increase of the mass concentration of sodium chloride has little effect on the apparent color depth of dyed fabrics, and its K/S value tends to be balanced. The UPF value of dyed fabrics showed a gradual upward trend with the increase of the concentration of sodium chloride. When the sodium chloride reaches 30g/L, the UPF value of the fabric does not change much. Therefore, the mass concentration of sodium chloride is selected to be 20-30 g/L.

5. Dyeing temperature

Disperse dye 1% (omf), neutral fixative reactive dye 3% (omf), UV absorber HLF 10% (omf), NaCl 30g/L, kept at different temperatures for 40min, and measured the K/S value and UPF value of the fabric.

It can be seen that with the increase of dyeing temperature, the apparent color depth of the fabric increases gradually. This is because neutral fixation reactive dyes can be fully combined with cotton fibers generally under high temperature conditions above 100 °C. As the dyeing temperature increases, the movement of the polyester macromolecular chain intensifies, and the disperse dyes are more likely to enter the interior of the polyester. When the dyeing temperature is 120～130℃, the K/S value of dyed fabric tends to be stable. With the increase of the fixing temperature, the UPF values of the three-color fabrics gradually increased. When the fixing temperature was 130℃, the UPF values of the fabrics reached the highest. This is because HLF is a dispersive UV absorber, and increasing the temperature can accelerate the diffusion of UV absorber molecules into the fiber. Therefore, the dyeing temperature is selected to be 120-130°C.

6. Holding time

Disperse dyes 1% (omf), neutral same-color reactive dyes 3% (omf), UV absorber HLF 10% (omf), NaCl 30 g/L, heat up to 130 °C, keep warm for different times, and measure the K/S of fabrics value and UPF value.

It can be seen that when the dyeing temperature rises to 130 °C, the K/S values of the three-color polyester-cotton fabrics have little change with the increase of the holding time, which is because most of the dyes have been dyed in the dyeing stage. It can be seen that when the temperature rises to 130 °C, the UPF value of the fabric increases rapidly with the extension of time within 10 minutes of heat preservation; if the heat preservation time is continued, the UPF value of the fabric increases slowly or tends to be stable, this is because the dyes and The UV absorber has reached the dyeing balance, and the UV resistance of the fabric is maximized. In order to ensure that the dye is fully dyed, the incubation time is selected to be 40min.

7. Color fastness

The polyester-cotton fabrics were dyed with disperse golden yellow/reactive yellow, disperse blue/reactive blue and disperse red/reactive red respectively under the optimal process. The polyester-cotton fabrics dyed in one bath with disperse dyes/neutral fixative reactive dyes/ultraviolet absorbers have good color fastness to dry rubbing and color fastness to washing, both of which are above grade 3.