Ⅰ. Working mechanism of fixing agent
Dyes are dyed on different fibers, and their dyeing mechanism and color fastness are different, so the fixing agent mechanism and application of the fixing agent are also different.
1. Use the quaternary ammonium salt or tertiary amine salt in the fixing agent molecule to bond with the anionic group in the ionic dye structure to make the dye and the fixing agent form an insoluble color block to settle on the fiber, thereby Improve the color fastness of dyes on fabrics.
2. Use the reactive group in the fixing agent molecule to cross-link with the reactive group on the dye molecule and the hydroxyl group on the cellulose molecule to reduce the water solubility of the dye.
3. Use the film-forming properties of the fixing agent on the fabric to improve its color fastness. In the high-temperature drying process of the dye-fixing agent, the reactive cross-linking groups on the dye-fixing agent molecules cross-link into macromolecules by themselves, forming a layer of protective film with a certain strength on the surface of the fabric and fiber, which wraps the dyestuff. Coated on the fiber, so that the dye is not easy to fall off.
Ⅱ. Types of fixing agent
According to the dye fixing agent mechanism, fixing agent can be divided into two categories: reactive fixing agent and non-reactive fixing agent.
1. Reactive fixing agent refers to the introduction of reactive groups into the molecules of the fixing agent, and epoxy groups are commonly used. This type of fixing agent can form a covalent bond with certain groups in the fiber dye molecule, which is more beneficial to the improvement of dye fastness.
2. Non-reactive fixatives refer to two types of film-forming and blocking water-soluble groups on the fiber surface. The main types are cationic fixatives and resin fixatives.