Spandex can be dyed with disperse dyes and acid dyes, but the fastness of these two dyes is different. The experiment shows that the reactive dyes (dyed with nylon elastic cloth) and disperse cationic dyes (dyed with CDP elastic cloth) of nylon are basically not dyed. Does it mean that these two dyes are not suitable for spandex dyeing? Actually not. On the premise of using appropriate additives as the medium, nylon with reactive dyes can dye spandex with good fastness and depth.
There are almost no pure spandex fabrics on the market, so spandex dyeing is unfamiliar. The elasticity and resilience of the fabric can be increased by using pure spandex fabric with low-tensile or non-tensile fabrics. And when the elastic fabric is stretched or pressed, if the color of Spandex elastic fiber is inconsistent with the filament, the color leakage of Spandex elastic fiber will occur, which requires dyeing Spandex elastic fiber.
For the light color dyeing of spandex, acid dyes or disperse dyes can be used for dyeing under the condition of acid bath. With the same amount of dyes, the fastness of disperse dyes on spandex is better than that of acid dyes, but the fastness of different disperse dyes on spandex is different. Similarly, when the amount of dyes is less than 0.5%, disperse dyes can be used.
Spandex is a high elastic fiber. Considering that long-term dyeing under high temperature conditions will lead to the loss of elasticity of spandex, it is generally carried out under 100 ℃, and spandex is not alkali resistant. In addition, disperse dyes and acid dyes are suitable for dyeing under acidic conditions. In order to dye in acid bath, pH 5 is more appropriate.
All kinds of dyes can use appropriate additives as the medium to dye spandex. This type of additive is called Spandex colorant or Spandex colorant on the market. It is mainly used to dye spandex with reactive dyes and acid dyes of spandex. Properties of zwitterions. Its working principle is as follows:
Under acidic conditions, amide bonds and other groups in spandex are ionized and positively charged. Spandex elastomer colorant reacts with it, and the fixative is fixed on Spandex elastomer. Because spandex colorants contain amino cations, dyes and spandex colorants can also be combined.
Dyeing rule of nylon reactive dyes on spandex (adding spandex colorant)
One. The general rule of color fastness of spandex after dyeing is: washing>sweat (acid)>water immersion. The color fastness to wet rubbing is much better than that to dry rubbing. Analyze the cause. After dyeing of spandex, the dye or spandex colorant and dye combination will migrate under the long-term action of external pressure under wet conditions, which is a slow process (spandex is hydrophobic fiber, water molecules will not enter the fiber quickly, and the dye will not migrate quickly), so its water washing fastness is better. Secondly, under the acidic condition of sweat, it is conducive to the ionization of amide bonds on spandex or amino groups on spandex colorants, and can capture the transferred dyes. Or the combination of spandex colorant and dye, so its fastness to acid perspiration is better than that to neutral water immersion. Under the action of friction, dry grinding will generate heat, which will lead to thermal migration of dyes on the surface of spandex. This will not happen under wet conditions.
b。 After dyeing spandex and boiling it with soda powder, its fastness will decrease by about 0.5. This is because under alkaline conditions, the combination of spandex colorant, fiber and dye will be destroyed and the fastness will be reduced. Secondly, after the Spandex fiber is dyed, it is fixed with cationic fixative, and its fastness is greatly improved than that of anionic fixative. The cationic fixative can react with the water-soluble group (- SO3 -) produced by the dye to block the water-soluble group. The water solubility of the dye is reduced, and the fixing agent forms a film on the fiber surface, which can isolate the dye and improve the dry rubbing fastness accordingly.
C。 Acidity, dispersion and light fastness of nylon and reactive dye dyed spandex are worse than those of polyester or nylon filament. The main reason is that the crystallinity of spandex is low and it is in a high elastic state at room temperature. Air is easier to enter the fiber, and the color will change under the action of sunlight. In addition, the spandex itself will turn yellow under the action of sunlight. Reasons for poor light fastness.
When the cotton stretch cloth is dyed black, the spandex will turn white. Generally, a small amount of dispersed or acid black can be added to the dyeing bath to dye the spandex, but the fastness should be paid attention to. Secondly, it is used for dyeing black of polyester stretch cloth and nylon stretch cloth