Spandex dyeing depth

Spandex dyeing depth
Abstract: The development status of spandex deep dyeing in recent years is introduced, which mainly includes 1:2 metal complex acid dyes dyeing spandex, dyeing auxiliaries to make spandex color, adding dyeing additives when spinning and improving spinning raw materials and processes. The principle and current situation are briefly described, and the development direction of spandex dyeability is pointed out.

01
Spandex
Spandex is a polyurethane fiber, with a large elongation, high recovery rate, a small amount of additives can improve the elasticity of the fabric and wearing comfort, known as the textile “MSG”. At present, the application of spandex is becoming more and more extensive, a variety of new fabrics and functional clothing will add spandex, and the amount of spandex is getting higher and higher, from 3% to 30%.
Spandex is mainly used in yarn wrapping, knitting, weaving and other textiles, but also in the field of hygiene products and medical applications, with the development of differentiated spandex, the scope of its application will continue to expand. Although spandex has many advantages, but in the dyeing performance, ordinary spandex on the dyeing rate and dyeing fastness is far from meeting the requirements, and other fibers blended with the phenomenon of “white”. Some high-grade fabrics and high spandex amount of clothing, the problem of white will seriously limit the application of spandex, therefore, the study of spandex dyeing dark color is crucial.
The chemical component of spandex is polyurethane, there are a small amount of amino acid in the molecule, therefore, at present, the dyeing of spandex mainly adopts acid dyes, through taking certain measures to improve the dyeing rate of acid dyes, to achieve the purpose of dyeing fabrics with dark colors.

02
The current situation of spandex deep dyeing
The dyeability of spandex mainly refers to the relative nylon using weak acidic dyes in acidic conditions, dyes and spandex terminal amino acid ionic bonding and dyeing. For how to improve the dyeing rate of acid dyes and increase the color depth of dyed fabrics, at present, mainly from the screening of dyestuffs, application of dyeing auxiliaries, spinning additives, spinning process to improve the current status of the research on each method and the mechanism is discussed.
2.1 Application of acid metal dyes
Spandex is spun from PTMG (polybutylene glycol) and MDI (isocyanate) through primary and secondary polymerization. There are amide bonds and a small amount of terminal amino groups on the macromolecular chain of spandex, and the structure is similar to that of nylon, so it can be dyed with weakly acidic dyes. Due to the relatively small number of terminal amino groups, the dyeing color is relatively light, far from the same color as the relative yarn nylon effect. Weak acid dyes can be divided into four categories: level dyeing type, semi-shrinkage type, shrinkage type and metal dyes (1:2 metal complex acid dyes), whose relative molecular mass and the depth of the dyed color increase in turn. Since spandex is a polyester fiber, the dyes with smaller polarity can increase the affinity to spandex, at the same time, the dyes with larger relative molecular mass can increase the van der Waals force with spandex, therefore, 1:2 metal complex acid dyes are more suitable for spandex dyeing type, this kind of dyes in neutral or weak acidic medium dyeing, so it is also known as neutral dyes.

After dyeing spandex, 1:2 metal complex acid dyes can either dye by ionic bonding with the terminal amino group or bond with spandex by van der Waals force, which can well improve the depth of dyeing of spandex, especially the big black and red colors which are easy to show white. Du and other neutral and weakly acidic dyes on the performance and process of spandex dyeing research, the results show that the 1:2 metal complex dyes on spandex dyeing performance is better than ordinary weakly acidic dyes; neutral dyes on the dyeing of spandex dyeing process is more suitable for: pH = 4, the temperature of 70 ~ 80 ℃, holding time of 40 ~ 60 min, the dyes enhancement is good.
At present, the market can be used for containing spandex, nylon fabric dyeing darker better metal dyes have Qingdao Double Peach neutral dyes series, including neutral black BL, neutral blue BNL, neutral orange RL, etc., ordinary acid dyes and Double Peach neutral black BL dyeing spandex color.
Comparison of the color of spandex after dyeing with neutral dyes and ordinary weak acid dyes.
Neutral black dyeing spandex can reach very deep black, the same color depth as the relative yarn nylon, can be a good solution to the spandex in the dyeing of dark colors of the problem of white. When the dyed color is deeper, the color fastness of the fabric to washing will be reduced.
2.2 The use of spandex coloring agent
Spandex coloring agent is a kind of ester containing amino, similar to the structure of spandex, so it can be well adsorbed on the surface of spandex, at the same time, this kind of auxiliary contains a large number of amino, which provides the dyeing seat for acid dyes to dye spandex, and it can improve the same-color property of spandex and nylon very well. When this additive is used, it is usually carried out in the same bath with dyeing, with the dosage of 0.5%~2.0% (omf), without increasing or changing the dyeing process, which is relatively convenient, and the dyeing effect is shown in Fig. 2.
The effect of spandex coloring agent on acid dyes on spandex dyeing
Acid dyes on nylon/spandex