1. Dye performance
When the cellulose fiber fabric dyed with reactive dyes is subjected to the wet rubbing fastness test, there are two main factors that cause color transfer: one is that the water-soluble dye is transferred to the rubbing fabric during rubbing, causing the original color to fade and make The rubbing cloth is stained; the second is that some of the dyed fibers break during rubbing, forming tiny colored fiber particles which are transferred to the rubbing fabric, causing staining. Therefore, the factors that may affect the color fastness of reactive dyes to wet rubbing are: the structure and characteristics of the reactive dyes themselves.
2. Color depth (dye concentration)
Studies have shown that the wet rubbing fastness of reactive dyed fabrics is closely related to the depth of dyeing, that is, when wet rubbing, the amount of color transfer and the depth of dyeing are almost in a good linear relationship. Among them, the dye is oversaturated during dyeing. It is the most important factor. When dyeing dark colors, the dye concentration used is higher, but it cannot greatly exceed the saturation value, because the excessive dye cannot be combined with the fiber, but can only accumulate on the surface of the fabric to form a floating color, which seriously affects the fabric Color fastness to wet rubbing. In addition, cotton fibers that have not been specially treated will swell under wet conditions, increase friction, and decrease fiber strength, all of which create good conditions for the breakage, shedding and color transfer of colored fibers. Therefore, proper pre-treatment of cellulose fiber before dyeing, such as mercerizing, singeing, cellulase finishing, scouring, bleaching, washing, and drying, can improve the surface finish and hair effect of the fabric and reduce friction resistance. , Reduce floating color, thereby effectively improving the color fastness to wet rubbing of the fabric.
3. The effect of floating color
Studies have shown that although the covalent bond strength, bond stability and adhesion formed by reactive dyes with different chemical structures and cellulose fibers are different, there is no significant difference in the effect on the color fastness to wet rubbing of dyed fabrics. . When the dyed fabric is wet rubbed, the covalent bond formed between the dye and the fiber will not break and cause floating color. The transferred dye is usually a dye that is supersaturated, does not form a covalent bond with the fiber, and only relies on van der Waals force to produce adsorption, the so-called floating color.
4. The impact of water quality
If harder water is used to convert the material, especially the fixing solution, because it contains CO32-, OH- and other anions, they will react with Ca2+ and Mg2+ to form insoluble substances such as Ca2CO3 and MgCO3. These insoluble substances combine with dyes to form lakes and deposit on the surface of the fabric, which greatly increases the frictional force during rubbing, thereby reducing the fastness to wet rubbing. In addition, Ca2+ and Mg2+ can also react with some anions on the dye molecule to transform into water-insoluble substances, thereby weakening the hydrophilicity of the dye, making the dye not easy to dissolve and diffuse, and the floating color is not easy to wash off when washing with water.
5. Fabric structure and surface finish
The structure of the fabric affects the smoothness of the fabric surface, and the smoothness determines the amount of friction received during the friction test and affects the rubbing fastness.
When performing wet rubbing, the situation is completely different from that of cellulose fibers. Due to the extremely low moisture absorption of the fiber or the insignificant water puffing effect, and the presence of water acts as a lubricant, the color fastness to wet rubbing of this kind of fabric is significantly better than the color fastness to dry rubbing. It is generally believed that the dry rubbing color fastness of textile products should be better than the wet rubbing color fastness, which forms a clear contrast, and often causes people's doubts.