Batch Dyeing Process is the most popular and common
method used for dyeing of textile materials. Batch dyeing is also
sometimes referred to as
Exhaust dyeing. This is because in this
process, the dye gets slowly transferred from a comparatively large
volume dyebath to the substrate or material that is to be dyed. The time
taken is also longer. The dye is meant to 'exhaust' from dyebath to the
substrate. In batch processes, textile substrates can be easily dyed at
any stage of their assembly into the desired textile product. This
includes fiber, yarn, fabric or garment. Some type of batch dyeing
machines can function at temperatures only up to 1000
oC. For
example cotton, rayon, nylon, wool etc. can be dyed at 1000
oC
or lower temperatures. While polyester and some other synthetic fibers
are dyed at 1000 Centigrade or even higher temperatures. There are three
general types of batch dyeing machines. The first type is the one where
there is circulation of fabric. Second type is the one where the dyebath
gets circulated while the material that is being dyed remains
stationary, and finally the third type where both the bath and material
to be dyed gets circulated. Examples of dyeing machines that utilizes
batch dyeing process are Beck, Jet, Jigs, Beam Package dyeing machines
etc.
For any dyers the ultimate dream is to get the
maximum out of the process of dyeing, at minimal cost. For a batch
dyeing process the following techniques can prove to be effective for
optimum utilization.
- Use machinery that are fitted with latest state-of-the-art
automatic controllers of fill volume, temperature and other dyeing
cycle parameters, indirect system of cooling and heating, innovative
hoods and doors that lessens vapour losses.
- Choosing the machinery that is exactly sized for the batch that
needs to be processed. Also confirmation that it is operated exactly
within the specified range of nominal liquor ratios for which it is
designed. It has been seen that machines that are operated with a
consistent liquor ratio while being loaded at 60 percent level of
their nominal capacity gives optimum results. With yarn dyeing
machines this level can stretch to even 30% of the nominal capacity.
- Opting new machineries that adheres to the following
requirements:
- Liquor ratio that is low-or-ultra-low.
- Complete in process separation of bath from substrate.
- Mechanism that involves smooth internal separation of process
liquor from the washing liquor.
- Mechanical liquor extraction that brings the carry-over to
minimum and improves washing efficiency.
- A reduced cycle duration.
- Replacement of conventional overflow-flood rinsing method with
methods like drain and fill or other methods (for example smart
rinsing for fabric).
- Proper re-use of rinsed water for the next dyeing session.
- Re-use of the dye bath if technical considerations allows.