Common Dyeing Equipment Processes and New Dyeing Techniques – Part 6
Section 2 Staining Methods – part 2
Padder dyeing method
Definition of padder dyeing:
It refers to the process of immersing a fabric in a dye solution for a short period of time (usually a few seconds or just in time), immediately pressing it with a roller, squeezing the dye solution into the fabric's structure and voids, and removing excess dye solution. The dye is then treated by steaming or baking to fix it in the fibers.
Rolling residual rate=[(weight of fabric after immersion - weight of fabric before immersion)/weight of fabric before immersion] x 100%
Swimming: refers to the phenomenon where dyes migrate from the inside of fibers to the surface of fibers during the drying process of fabrics after immersion in dye solution.
To reduce swimming displacement, the following measures can be taken:
(1) Reduce rolling residual rate
(2) Using infrared pre drying - hot air drying - dryer drying (temperature from low to high)
(3) Wrap the outside of the drying drum with cloth
Dipping and rolling method
There are generally one dipping and one rolling, two dipping and two rolling, and multiple dipping and one rolling (or multiple dipping and two rolling). It depends on the fabric, dye, and equipment. The fabric is thick, has poor permeability, and requires a high amount of dye, generally it does not need one dipping and one rolling.
Dyeing concentration: usually expressed in g/L. The number of grams of dye contained in 1L of dye solution.
Features and Applications
Pad dyeing is a continuous production process with high production efficiency and is suitable for large-scale processing. However, dyed fabrics generally experience high tension and are usually used for dyeing woven fabrics, as well as for dyeing tow and yarn.
How to overcome color difference in pad dyeing
*Left center right color difference
(1) Add an appropriate amount of wetting or penetrating agent to make the fabric absorb liquid evenly
(2) The pressure on the roller should be uniform and consistent, and a uniform padder should be used to avoid the phenomenon of dark colors in the middle and light colors on both sides caused by ordinary padder (only applying pressure at both ends of the roller). Namely, grind one of the roller into an olive shape (the middle diameter is slightly larger than the two ends)
*Color difference before and after
(1) Dyes with high fiber directness can cause a color difference between the front and back, which can be solved by diluting the dye solution in the rolling tank during initial rolling dyeing.
(2) Dyes that have no direct effect on fibers may produce a phenomenon of front fading and back thickening, which can be solved by thickening the dye solution in the rolling tank during initial rolling dyeing
In view of the above situation, when color matching and pad dyeing, it is advisable to choose dyes that are directly similar in color matching.
AT274 Series Pneumatic Heavy Duty Padder from Anytester is the padding mangle for all dyeing, printing, finishing and padding processes, widely used in dyeing and finishing plant and manufacturer of and dyes. Click here to learn more.
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