Chlorine in tap water is the main reason for the color change and even fading of dyed fabrics. When washing clothes, the dye reacts directly with available chlorine, and the dye is oxidized to fade and change color. Even a small amount of chlorine will degrade dyes, especially reactive dyes, and the color of clothing will change during washing.
It is generally believed that chlorine reacts with dyes and dye matrix to change or even destroy the chromophore, or break the covalent bond between dyes and fibers. Therefore, the fixation mechanism of chlorine resistant fixing agent is to make the fixing agent react with reactive chlorine before the dye, so as to avoid the destruction of the covalent bond between the dye and the fiber, play a protective role and improve the chlorine resistance of the dyed fabric. Therefore, chlorine resistant color fixing agents have attracted extensive attention.
The chlorine resistant fixing agent must have the following characteristics: (1) the oxidation potential of chlorine resistant fixing agent is lower than that of dye, and its oxidation rate is higher than that of dye; (2) Chlorine resistant color fixing agent can be adsorbed on a large number of fibers, and it is not easy to be desorbed in soaping and other processing.
Substances with good color fastness to chlorine are generally oxygen resistant substances, resins and polyamines. For example, after polyamines are applied to the fabric, reactive chlorine can react with amine, so as to avoid or reduce the damage of dyes. At present, most of the developed polyamine compounds, such as dimethyl diallyl quaternary ammonium salt (DMDAAC), react with sulfur dioxide under the initiation of free radical to form polysulfone polymer, which can prevent color change, chlorine resistance and reduction of color fastness to sunlight. The sulfonyl group (- SO2) in the molecular structure is a reducing group, which can react with reactive chlorine first to protect the dye from attack. However, the disadvantage of polysulfone is that its color fastness to washing is not high, and because sulfonyl groups are easy to cause alkaline hydrolysis, the color fastness will gradually decrease with time.
Generally speaking, the domestic research on chlorine resistant color fixing agents is still relatively small, and the research on the chlorine resistance of color fixing agents needs to be further strengthened. We should vigorously develop chlorine resistant color fixing agents with excellent performance.
