Use Pad Batch Dyeing

[1] [6] [28] It is the transfer of dye to cotton, rayon and blended goods through rollers (continuous method), according to reference [2]. As described in references [10] and [30], prepared fabric is impregnated with liquor containing premixed fibre reactive dyestuff and alkali; excess liquid is squeezed out on the mangle. The fabric is then batched onto rolls or in boxes and covered with plastic film to prevent carbon dioxide absorption from air or water evaporation, then stored for two to twelve hours. Goods can be washed in any of several convention ways, depending on equipment available in the mill.

The features of this method listed in the consulted bibliography are:

• cellulose dying is one of the most reliable and controllable methods available today [10] [30] for dyeing cellulose
;
• chemical use, including alkali as well as specialty chemicals with associated BOD and COD loadings for waste streams, can be reduced up to 80% compared to atmospheric becks [10] [30]
;
• salt consumption is reduced from about 100% on weight of goods to zero [10] [30]
;
• water consumption for pad-batch dyeing with beam wash-off is typically less than 16 m³ per tonne of dyed fabric, compared to typically 160 m³ or more on atmospheric becks for the same fibre-reactive dyed shades [2] [10] [30]
;
• energy consumption is reduced from 19 GJ per tonne of dyed fabric for becks to under 4 GJ per tonne [2] [10] [30]
;
• labour costs are also reduced. As an example, extracted from references [10] and [30], two workers per shift can dye 100 tonnes of fabric per five-day week
;
• outstanding shade reproducibility [10] [30]
;
• excellent penetration, and leveling characteristics [10] [30]
;
• rapid fixation [10] [30]
;
• quality of pad-batch dyeing is equal to or better than other dyeing systems. According to Smith [30], lower defect levels mean less redyeing, less use of stripping agents, and less waste from re-dye operations
.

References from reviewed literature:

In [2] B. Smith, A Workbook for Pollution Prevention by Source Reduction in Textile Wet Processing, Pollution Prevention Pays Program, North Carolina Department of Environment, Health, and Natural Resources, Raleigh, N.C., 1988