Fixing way of non-formaldehyde fixing agent for textiles
1. Utilize the positive group in the fixing agent molecule and the anionic group of the dye to form an electrostatic bond, so that the dye and the fixing agent settle on the fiber, reduce its water solubility and improve the soaping of the dye and the fastness of the white cloth. The stronger the cationicity of the fixing agent, the better the color fastness to soaping and white cloth staining. For example, the introduction of quaternary ammonium salt groups can improve the fixing effect of the fixing agent. The fixing agent of Shanghai Auxiliary Factory DUR and fixing agent TCD-R, EccofixFD-3 are examples of this.
2. Use the reactive groups in the fixing agent molecule to cross-link with the reactive groups on the dye molecule and the hydroxyl group on the cellulose molecule, thereby reducing the water solubility of the dye and improving the soaping, staining and wet ironing of the dyed material Fastness. The so-called wet ironing fastness is the fastness of the broken bond and floating color of the reactive dyes from the dyed material to the ironed wet cloth when ironing on the wet cloth. To improve the wet ironing fastness, the use of crosslinking agents is a more effective method. Through cross-linking between the dye and the fiber, the dye from the broken bond is no longer transferred from the dyed material to the ironing cloth. Introducing reactive groups (mainly epoxy groups at present) into the fixing agent can improve wet ironing fastness. Commercial fixing agents usually have insufficient content of reactive groups, and the effect of improving wet ironing fastness is not as good as cross-linking. The agent is obvious. If the fixing agent is a high polymer and contains the same number of reactive groups, its ability to improve wet ironing fastness is often worse than that of the fixing agent with low molecular weight.
3. Use the film-forming properties of the fixing agent on the dye to improve its color fastness. The test results show that the fixing agent with good film-forming properties has better fixing effect. The high polymer polymerized by olefin can improve the color fastness even if it does not contain reactive or cationic groups. This is because the high polymer forms a film on the surface of the dyed material, which reduces the dissolution of the dye, and the polyamine The color fastness of the color-fixing agent can be improved after the molecular weight is improved. If reactive groups or cationic groups are introduced into the film-forming material, the color fastness can be improved even more. Now most of the new type fixing agents take this approach.
4. Use the molecular attraction between the fixing agent and the fiber to increase the fixing strength of the fixing agent, thereby improving the color fastness. The intermolecular attraction referred to here is mainly hydrogen bond attraction. The fixing agent made of polyvinyl polyamine and epichlorohydrin has better color fastness than the fixing agent made of dimethylamine and epichlorohydrin. This is the reason. Another example is the condensate of diethylenetriamine and dicyandiamide. Its fixation effect is mainly due to its strong hydrogen bond attraction and weak cationicity. In addition, the amount ratio of n (diethylene triamine): n (epichlorohydrin) is generally 1:1 condensate. If the amount of epichlorohydrin is increased, a three-dimensional condensate can be formed. The increase in reactive groups in the chromosome should improve the fixing effect, but the fact is the opposite. The reason is that this fixing agent has a three-dimensional structure rather than a planar structure, which weakens the hydrogen bond attraction between the fiber and leads to the fixing effect. The reduction.
5. Use the buffering capacity of the fixing agent to improve the perspiration fastness of the dyed material. As we all know, reactive dyes are not resistant to acid attack. In an acidic environment, the covalent bond formed by the dye and fiber will be hydrolyzed and broken, which will easily lead to a decrease in sweat fastness. Because sweat often contains acidic substances, we want to improve sweat fastness. There should be strong acid absorption capacity in the molecular structure. That is to have a good buffering capacity, so it is best to have a nitrogen atom in the fixing agent molecule. Using polyolamine condensate as a fixing agent has better perspiration fastness than polyacid condensate or naphthalene diphenol condensate. Proof.
6. Use the smoothing agent in the fixing agent to make the fiber surface smooth and soft, thereby improving the rubbing fastness of the dyed material. So far, the wet rubbing fastness of color fixing agents produced at home and abroad can generally only reach 2 to 3, and there is no fixing agent that can reach 3 or above. The reason is that the aldehyde-free fixing agent is After filming, its smoothness has not improved much. For this reason, fixing agents dedicated to improving wet rubbing fastness are being developed recently at home and abroad, and products have been sold. These special additives are actually softeners, such as Polyethylene emulsion, amino silicone oil after screening, etc. These softeners are only effective when the dosage is large (more than 50g/L). The use of this kind of additives can only be mixed with the fixing agent. Therefore, a soft substance that can be grafted with the fixing agent is currently being developed to achieve the purpose of softening and improving wet rubbing fastness.
7. Utilize grafting method to introduce ultraviolet absorber into fixing agent molecule to improve the light fastness of reactive dyes. The light fastness of reactive dyes is far inferior to that of soluble vat dyes and vat dyes. Especially when the color is light, the fastness is not ideal, so it is urgent to use fixing agent to improve it. At present, the UV absorber can be used to improve the light fastness by half, but the durability is not ideal. Therefore, seeking more effective methods is the current scientific research content. Whether the UV absorber is introduced into the fixing agent molecule will reduce the anti-ultraviolet effect remains to be tested.