Since the 1930s, many foreign chemical companies have begun to develop various color fixing agents. Before World War II, copper salt or cationic surfactant was often used to fix direct dyes. This direct dye is copper salt direct dye. Copper salt has a complexation effect on direct dye molecules, and a complex is formed in the process of fixing, which improves the soaping fastness of fabrics. After the end of World War II, the Czech Republic first invented the color fixing agent y, which was later introduced into the Soviet Union and then to China. It is an oligomer with network structure formed by the condensation of dicyandiamide and formaldehyde. It is weakly cationic and can form a hydrogen bond with the fiber, which can be firmly bonded to the fiber by gravity. The network structure reduces the water solubility of direct dyes, thus improving the color fastness. It is generally used for the color fixing of direct dyes and acid dyes, and the color fixing effect is good. Later, the copper complex color fixing agent M of color fixing agent y was developed, which can improve the sun fastness, but it is easy to cause the content of heavy metals on the fabric to exceed the standard. The study also found that the color fixing agent y will release formaldehyde after finishing, causing damage to human skin and body. In order to prevent the harm of formaldehyde to human body, many countries have formulated various laws and regulations to limit the content of formaldehyde in textiles. For example, the Oko tex standard of France and Germany stipulates that the formaldehyde content of clothing that does not directly contact the skin should be less than 300mg / kg, while the formaldehyde content of medical supplies for newborns should be less than 20mg / kg.
In the 1980s, China began to develop formaldehyde free color fixing agents. Dimethylamine or trimethylamine reacts with epichlorohydrin condensate or diethylenetriamine reacts with epichlorohydrin condensate to synthesize oligomers with cationic groups to form quaternary ammonium salt or tertiary amine. At the same time, there are reactive groups, which can bridge between dyes and fibers, so that they can be combined more effectively, so as to improve the wet treatment fastness of water-soluble dyes. Later, a resin type color fixing agent was developed. The resin with cationic imidazoline structure was formed by the condensation reaction of dicyandiamide and divinyltriamine, which was called resin type color fixing agent. The treated fabric was easy to produce color change. If it is condensed with epichlorohydrin and connected with reactive groups, it will become a reactive resin color fixing agent, which can improve the fabric ironing fastness; or it can be condensed with D resin and introduce hydroxymethyl, which can be condensed with fibers or dyes during baking, so as to improve the color fixing effect.
In the 1950s, foreign countries studied the polymer of Dimethyldiallyl Ammonium Chloride and made a high molecular cationic color fixing agent. This high molecular weight material can form a film on the fabric to prevent the dissolution of dyes. Its cationic group can form quaternary ammonium salt with the water-soluble group in water-soluble dyes to improve the fastness to wet treatment. It is the most widely used color fixing agent at present.
Aiming at the problem of poor wet treatment fastness of water-soluble dyes, the above types of color fixing agents are the most used color fixing agents in the market. Later, they were transformed on this basis, and a wide variety of color fixing agents appeared one after another.
