How to overcome the twist of viscose filament yarn in printing and dyeing colors
The dyeing of viscose filaments is prone to chromatic aberration. The reasons are:
① The form of multiple pages in vertical slits on the surface of the fiber, so hygroscopicity, throughout the wet treatment (pre-treatment and dyeing), yarn shape variation, weight increase, directly affects the effect of wet treatment;
②Viscose fiber, viscose filament, amorphous and crystalline area irregular, with raw materials, during the spinning process, especially in common areas;
③ Especially for silk and viscose yarn, the pre-treatment of printing and dyeing machinery has not been widely adaptable, and it has been proved that the spray dyeing machine is preferable;
④ The advantages of ordinary silk and viscose filament are that they are due to the bright silk in the application, which has certain limitations to help improve the performance of spinning and fiber, spinning matting agent, adding (titanium dioxide) and Smooth, soft, anti-mildew, anti-foam, anti-static, anti-oxidant surfactants, from matt and semi-matt silk and silk, due to the different degrees of light refraction and gloss of silk, there are differences in color, therefore, to overcome the color Spot-colored yarns, viscose filaments themselves, first of all, have a certain understanding of physical and chemical properties.
Second, please note the following three points in dyeing:
First, strengthen the pre-treatment to promote fiber swelling, and remove the additives from the fiber surface to meet the basic dyeing requirements of the yarn. The process of making the following recommendations:
Sodium hydroxide () 2-5
Sodium carbonate 2-4
Scouring agent HS-120A (Wuxi closed) 3-5
Process conditions (jet dyeing machine)
Bath ratio 1:10-15
Maintain temperature (℃) 95-98
Holding time (min) 60-90
Thorough removal Because sodium hydroxide is easy to clean, so after washing, also use 98% acetic acid solution 2ml / L, (room temperature), the fiber remains neutral until the dye proves that it is better, and the effect of the fiber is very small. The scouring agent HS-120A is an anionic/complex and non-ionic emulsion with anionic part for washing effect, excellent dyeing and other properties. The non-ionic part is pretreated at a higher temperature for a long period of time, but in each Batch viscose filaments are very different, so they are passed on a small scale before being officially put into production.
Second, we must choose the dye transfer and dye leveling is better. The initial infection rate of viscose fiber is very high, but the absorption rate is not high, the flowers, colors and other defects of the dye color produced, even if the dyeing time is extended, the dye can not be selected in general, direct and reactive dyes should choose the water-soluble group (- SO2Na) molecular structure, more is better. The solubility of the dye should be large and directly low. The purpose is to reduce the incidence of initial infection and improve the leveling property. At the same time, the water hardness should not be too high. In addition, the chelating dispersant and the better leveling agent are used for dyeing. Run for 10-15 minutes. In addition to the dye, the compatibility of the dye should be selected close to the three primary colors.
Third, it is appropriate to strictly control the process conditions, especially the heating rate usually at 1°C/min. In addition, whether it is a direct dye or a reactive dye, supplementary electrolyte (sodium sulfate or sodium chloride) is used as an accelerator, which also adds alkali to fix the color. The dilution of electrolyte and alkali is increased by 3-4 times to ensure the absorption rate of dye. In general, the lower the initial dyeing, the higher the dyeing rate is not necessarily lower at the end, you can extend the dyeing time. The dyeing time of the insulating viscose yarn (yarn) is about 90 minutes. Depending on the dyeing depth, it may be because only the dye is passed to obtain the correct shade and good color fastness.