The reactive groups on the molecular branches of the color fixing agent are crosslinked with the reactive groups in the dye and the hydroxyl groups in the fabric fiber respectively. In this fixation mechanism, the color fixing agent acts as an intermediate and reacts with the fabric and dye respectively, making it difficult for the dye to fall off and peel off from the fabric, which can significantly increase the color fixing effect, especially the wet ironing fastness of the fabric dyed with reactive dyes. At present, in the synthesis process of color fixing agent, epoxy group is mostly used as the reaction group in the molecule, which is introduced into the molecular branch of color fixing agent by grafting or other methods under certain conditions, and then the color fixing effect is enhanced through the cross-linking between the reaction group and fiber and dye. The preparation of color fixing agent by using this principle has become a key topic concerned by many scholars in the industry. For example, after the polyamine resin is prepared with dicyandiamide and diethylenetriamine as the main raw materials, epichlorohydrin is added to the reaction system as the addition of reactive groups, so as to make a reactive color fixing agent. The color fixing agent is also one of the hot topics in the research of color fixing agent.
Color fixing agents using this mechanism for color fixing usually belong to reactive color fixing agents. If judged according to the molecular structure of color fixing agents, reactive color fixing agents can be divided into two categories. One is cationic reactive color fixing agents with cationic groups on the molecular branch chain. For example, color fixing agent YSZ. A cationic reactive color fixing agent with excellent color fixing effect was synthesized by using polyamine, acryloyl chloride and epichlorohydrin as main raw materials. The other is non-ionic reactive color fixing agents with active groups such as hydroxyl groups on the molecular branches of color fixing agents. For example, the color fixing agent TX. The color fixing agent is prepared by the reaction of phenolic compounds and epichlorohydrin, which has a significant effect on the wet rubbing fastness of fabrics.
Some studies have found that there is a certain molecular gravity between the color fixing agent and the fiber of the fabric. The molecular gravity here mainly refers to the hydrogen bond gravity. The size of the hydrogen bond gravity can determine the color fixing strength to a certain extent. For example, many color fixing agents made from polyethylenepolyamine and epichlorohydrin or condensation of polyethylenepolyamine and dicyandiamide strengthen the effect through the force between the color fixing agent and the fiber and the dye. At the beginning of the 21st century, more and more color fixing agents will use this mechanism for color fixing. Such as fixing agent CS. The color fixing agent typically uses diethylenetriamine and epichlorohydrin as raw materials to obtain an aldehyde free color fixing agent after polymerization. The color fixing agent uses molecular gravity to achieve color fixing effect.
