Jig dyeing

Figure 12.22 Variations in the concentration of sodium dithionite in jig dyeing using conventional and automatic dosing methods [225]...

Cellulose Diacetate. When preparing cellulose diacetate for dyeing, strong alkahes must be avoided in the scouring of acetate because the surface of the cellulose acetate would be saponified by such treatment. Many fabrics tend to crease and therefore requke open-width handling. Scouring is frequendy carried out on a jig or beam using 1.0 g/L of surfactant and 0.5—1.0 g/L tetrasodium pyrophosphate for 30 min at 70—80°C. 

Very small quantities of acetate staple are dyed, however, large quantities of acetate filament are found in satin, taffeta, and tricot fabrics these are usually dyed open-width on a jig owing to thek inclination to crease or crack easily. A typical dyeing procedure on the jig involves addition of acetic acid and dispersing agent over two ends at 50°C. The disperse dye is added over two ends and the dyebath temperature is gradually raised to 80°C in 5°C increments with two passes at each temperature. The dyeing is completed after 30—60 min at 80°C. 

Many improvements have been made to streamline performance and to reduce machine operation labor. Some of these are tensionless jigs using variable speed electric motors with built-in drag for brakes, automatic reversing equipment, and automatic temperature and level controls. These machines are widely used for goods that are easily creased, such as fabrics consisting of filament acetate, heavy filament nylon, or cotton duck. They are also convenient for small dye lots and for sampling purposes. 

The pad jig process represents the easiest type of fixation of pad dyeings. The material padded with dye is passed through a salt liquor in a jigger at 80-90 °C, thus preventing desorption of the dye. In this process, additional dye can be added during jigger treatment for shading. 

In the pad jig process, after the material is padded with dye and wetting agent, it is treated in a jigger at the dyeing temperature. The liquor contains the reducing agent, salt, and some padding liquor. 

Fabrics are dyed in machines that move them through the dye liquor either under tension (jig) or relaxed (beck). Fabrics also can be dyed in full width by winding them on a... 

As mechanical agitation is important to effect the bio-fmishing, only selected processes and machines can be used, for example tubular fabric preferably cut to open width and treated in open width washers. In the rope form the loosened fibre particles are filtered out by the fabric and cannot easily be removed. The pad-batch process, jig or package dyeing machines are not effective in bio-fmishing. 

A vat dyeing assistant in low concentrations A vat stripping agent at higher concentrations A leveling agent for continuous vat dyeing and pad-jig work... 

As a general rule, the jig roll of nylon is given 1 to 2 ends through a solution of CNC LEVELER P and acid or alkali to prepare the goods for the addition of dye and the start into a subsequent dye cycle. 

CNC WET SS-80 is soluble in any proportion in cold or warm water as little as 0.25%. CNC WET SS-80 does an excellent job as a wetter or scour in the kier, open width boil-off, package machine, pad box, jig or dye beck. 

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