Spandex dyeing depth can not be reached, how to do?

Spandex dyeing depth can not be reached, how to do?
Abstract: The development status of spandex dyeing depth 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. It briefly describes its principle and current situation, and looks forward to the spandex dyeing depth, pointing out its development direction.

Spandex
Spandex is a polyurethane fiber, with 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, and by taking certain measures to improve the dyeing rate of acid dyes, it can achieve the purpose of dyeing deep colors of fabrics.
The current situation of spandex deep dyeing
The dyeing 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, increase the color depth of dyed fabrics, at present, mainly from the screening of dyes, dyeing additives, spinning additives, spinning process to improve the current status of the research on each method and the mechanism is discussed.

1、Application of acidic metal dyes
Spandex is spun from PTMG (polybutylene glycol) and MDI (isocyanate) through primary polymerization and secondary polymerization, there are amide bonds and a small number of terminal amino acids on the macromolecular chain of spandex, the structure is similar to that of nylon, and therefore can be dyed with weakly acidic dyes. Due to the relatively small number of terminal amino groups, the dyeing color is 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 called 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.

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