For many years, the fixation method after dispersion dyeing has been a classic combination of sodium hydroxide and caustic soda. This method is simple to operate, cost-effective, and has good color fixation effect, and has been used to this day.
The fixation process of sodium hydroxide and caustic soda utilizes the strong reducibility of sodium hydroxide under alkaline conditions to remove floating colors on the surface of the fabric and improve its fastness. A suitable amount of sodium hydroxide and caustic soda is used for fixation; After increasing the dosage, it is called stripping. It is generally used when deep dyeing requires re dyeing or modification, but it will damage the strength of the fabric fibers to varying degrees. Improper operation can easily cause fabric scrap.
The fixation method of sodium hydroxide and caustic soda has many advantages, but also many disadvantages, mainly manifested in safety and environmental protection.
Summary of Defects in Solid Color Fixation of Sodium Hydroxide and Caustic Soda
Insurance powder can spontaneously ignite when exposed to water, posing a high fire hazard;
Insurance powder has poor stability and is prone to decomposition in humid and hot environments, resulting in a decrease in reducing power and affecting effectiveness;
The thermal stability of insurance powder is poor, and it disperses quickly in water above 60 ℃, resulting in low effective utilization rate;
After the decomposition of insurance powder, it will produce irritating SO2 gas, which seriously affects the production environment and personal health;
Insurance powder must be used in the presence of alkaline agents, so it is not suitable for fixing wool and silk fabrics;
High operational requirements, chemical materials are prone to uneven fixation (color splashes);
The residual liquid after fixation has reducibility, which increases the burden of sewage treatment.
Given the above, the industry has been exploring other disperse dye fixation processes and products.
Part 2. New Disperse Dyeing Fixation Scheme
The principle of a new fixation method is to improve color fastness by removing dye particles (floating colors) that are not fixed on the surface of the fabric.
At the same time, it can be combined with a fastness enhancing agent to adsorb and form a film on the surface of the fabric, preventing the migration of dispersed dyes from the inside of the fiber to the fiber surface during high-temperature baking, thereby improving the color fastness to washing and friction of the fabric.
By comparing the following experimental processes, the specific performance of the new and old processes can be clearly understood:
1. Experimental theme: Comparison of new polyester color fixing agent and sodium hydroxide+caustic soda color fixing process
2. Experimental fabric: 99% polyester fabric
3. Experimental auxiliary agent: insurance powder (90%)
Caustic soda (99%)
HAC (98%)
Polyester fixing agent DYETEX ECO
Fastness enhancing agent FUNCTEX F-4122
4. Experimental steps: dyeing → reduction cleaning → color fastness measurement
4.1 Staining
Formula: Disperse Red Jade 2.5%
Leveling agent 0.5%
HAC 1.0g/L
Process: Direct rise of 130 ℃ × 60min
Zhejiang Chaoyu New Material Technology Co., Ltd
Suzhou Chaoyu Textile Chemical Co., Ltd
