In the dyeing and finishing process of pure cotton knitted fabrics, after the fabrics are dyed, fixed and softened, they often need to be repaired due to dyeing defects. Before the fabric is repaired, it is necessary to remove solid, silicon, and even peel off the color.
Sometimes after solidification, silicon removal, and washing, if it encounters partial color difference, shade deviation, color change, etc., it is necessary to add dyes and counterstaining; sometimes after solidification, silicon removal and stripping, if it encounters For up-cast color difference, color flower and color stain, etc., it needs to be dyed again.
For fabrics that have not been fixed and softened, they usually only need repairing and re-dyeing, which are relatively easy to repair and re-dye. After fixing and softening, especially after baking or heat After setting the shape of the pure cotton knitted fabric, the difficulty of repairing is greatly increased.
Characteristics of fixing agent and softener
1. Fixing agent
In order to improve the color fastness of pure cotton fabrics to soaping, the fabrics need to be fixed and finished after dyeing, especially the deep and dense fabrics dyed with direct and reactive dyes.
The fixing agents currently used are basically formaldehyde-free cationic fixing agents, which are stable in weak acid baths and can combine with dyes through ionic bonds to form insoluble lakes and deposit on the fibers to reduce their water solubility and improve fabrics. Fastness to soaping.
Before repairing, if the fixing agent remaining on the fiber and its products with the dye are not fully removed, the dye uptake will be extremely fast during counter-dyeing. If the dye migration is poor, it will inevitably lead to stains and stains. , Even if the leveling agent is added, it will not help. If the dyed fabric is baked, the stains and stains will become more serious.
2. Softener
Softeners can be divided into cationic, anionic, nonionic and amphoteric types. Among them, amino silicone oil cationic softeners have excellent lubricating effect, mainly through self-crosslinking condensation to generate elastic network structure polymer on the fiber surface, which can give fabrics a soft hand and high washing resistance. However, if the higher dye fastness needs to be repaired, it will make counter-dyeing more difficult.
Currently, commercially available silicone oil softeners mainly include amino polysiloxane, epoxy polysiloxane, polyether polysiloxane, polyether epoxy polysiloxane, and polyether amino polysiloxane. If it is a fatty acid derivative softener, it can be removed from the fabric by washing with hot water or adding a small amount of alkali agent.