1. Use the calculating groups in the fixing agent molecule to form an electrostatic bond with the anionic groups of the dye, so that the dye and the fixing agent settle on the fibers, reduce their water solubility and improve the soap washing and white cloth of the dye. The stronger the cationicity of the color fixing agent, the better the color fixing fastness of the soap washing and white cloth. For example, the introduction of quaternary ammonium salt groups can improve the color fixing effect of the color fixing agent. Shanghai Auxiliary Factory The fixing agent DUR and the fixing agent TCD-R and EccofixFD-3 are in this example.
2. Use the reactive groups in the fixing agent molecule to cross-link with the reactive groups and cellulose molecules on the dye molecule to reduce the water solubility of the dye and improve the soap washing and white cloth dipping of the dye Color and wet fastness. The so-called wet hot fastness is the fastness of the broken bonds and floating color of the active dye when ironing the wet cloth. To improve the wet hot fastness, the use of crosslinking agent is a more effective method. The dye and the fibers are cross-linked so that the dye that has been broken off the bond is no longer transferred from the dye to the ironing cloth. Introducing reactive groups (currently mainly epoxy groups) into the fixing agent can improve the wet fastness. The commercially available fixing agents are usually not as effective as cross-linking due to insufficient reactive groups content. The agent is obvious. If the fixing agent is a polymer and contains the same number of reactive groups, its ability to improve wet fastness is often worse than that of the low molecular weight fixing agent.
3. Use the film-forming properties of the color fixing agent on the dye to improve its dyeing fastness. The experimental results prove that the color fixing effect of the color fixing agent with good film-forming properties is better. The polymer made of olefin polymer can improve dye fastness even if it does not contain reactive groups or cationic groups. This is because the polymer forms a film on the surface of the dye, reducing the dissolution of the dye, and polyamines After improving the molecular mass, the dyeing fastness of the color fixative agent can also be improved. If reactive groups or cationic groups are introduced into the film forming materials, dyeing fastness can be improved. Nowadays, most new color fixing agents take this approach.
4. Use the molecular gravity between the fixing agent and the fiber to increase the fixing strength of the fixing agent, thereby improving the dyeing fastness. The intermolecular gravity referred to here is mainly hydrogen bond gravity. The color fixing agent made of polyethylene polyamine and epoxychlorohydrin has better dye fastness than the color fixing agent made of dimethylamine and epoxychlorohydrin. This is why. For example, the condensation of diethylene triamine and dicyandiamide, the color fixing effect is mainly due to its strong hydrogen bond gravitational force and its weak cationicity. In addition, the amount ratio n (diethylenetriamine): n (epoxychlorohydrin) is generally 1:1 condensate. If the amount of epoxychlorohydrin is increased, a three-dimensional condensate can be formed. The reactive groups in it increase, and the color fixation effect should be improved, but the fact is the opposite. The reason is that this color fixation agent is a three-dimensional structure rather than a planar structure, which weakens the hydrogen bond gravity with the fibers, resulting in the color fixation effect. The reduction.
5. Use the buffering ability of the color fixative to improve the sweat fastness of the dye. As we all know, reactive dye dyes are not resistant to acid invasion. The covalent bonds formed by dyes and fibers will hydrolyze and break in acidic environments, making them easy toThis leads to a decrease in sweat fastness, because sweat often contains acidic substances. To improve sweat fastness, the molecular structure of the color fixing agent should have a strong acid absorption ability. That is to say, it is necessary to have good buffering capacity, so it is better to have nitrogen atoms in the fixing agent molecule. Using polyol amine condensate as the fixing agent is better than that of polyacid condensate or naphthalene diphenol condensate. This is a clear evidence. ．
6. Use the smoothing agent in the color fixing agent to make the fiber surface smooth and soft, thereby improving the friction fastness of the dye. So far, the wet friction fastness of the color fixatives produced at home and abroad can generally reach 2 to 3 levels, and there is no color fixative that can reach 3 levels or above. The reason is that there is no aldehyde-free color fixative. After the film, its smoothness has not improved much. For this reason, color fixing agents are being developed at home and abroad to improve wet friction fastness, and there are already products for sale. These special additives are actually softeners, such as Polyethylene emulsion, screened amino silicone oil, etc. These softeners can only be effective when the dosage is large (more than 50g/L). Using this type of additive, only the method of mixing with the fixing agent can be used, so soft substances that can be grafted with the fixing agent are currently being developed to achieve the purpose of being both soft and improving wet friction fastness.
7. Use grafting method to introduce ultraviolet absorbers into the color fixing agent molecules to improve the sun fastness of the reactive dyes. The sun fastness of reactive dyes is far less than that of soluble reducing dyes and reducing dyes. Especially in light colors, the fastness is even less ideal, so wait for the color fixing agent to improve it. At present, half-level of improving sun fastness can be used to treat ultraviolet absorbers, but the durability is not ideal. Therefore, seeking a more effective method is the current scientific research and development. Whether the ultraviolet absorber will reduce the anti-ultraviolet effect if it is introduced into the color fixing agent molecule remains to be proved.
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