Cold Pad Batch Chemical Finishing Machine

Cold Pad Batch Chemical Finishing Machine

The cold pad batch chemical finishing machine is a dyeing technique that actively dyes cellulosic fibers like cotton and viscose. It operates continuously at low temperatures and uses Cold to Medium Brand Reactive Dyes. It reduces the consumption of water, energy, and chemicals compared to exhaust dyeing, making it an environmentally friendly alternative. It also eliminates the need for steaming, which saves on energy.

The fabric that undergoes the cold pad batch dyeing procedure is able to retain a uniformly coloured appearance with added luster and gentle feel. The dyeing process is also able to achieve good lab to bulk transferability and excellent face-back uniformity. It is also able to provide fastness performance that meets or exceeds accepted fastness norms.

In this dyeing method, the fabric is padded with a mixture of reactive dye and alkaline agent in a padding mangle. It is then rolled into a bundle and wrapped in plastic sheets. It is stored in a cool place for 16-24 hours, during which the fabric must be slowly rotated to prevent seepage of the dye solution. This time is required to ensure that the pad has a consistent thickness.

During the dyeing process, the nip lines on the fabric are free of tension, which is crucial for a high level of uniformity. This is because the nip lines must be able to compensate for varying fabric compression. Moreover, the fabric must be evenly nipped across the width of the swatch. In addition, the nip line must be flexible to allow the pad to reach all parts of the fabric.

Before the nip line is inserted into the machinery, the fabric must be pretreated to remove any oils or sizing that may interfere with dye penetration. This step is important because it can significantly improve the color intensity, evenness, and fixation rate. It is also important to use a soft alkali system for best results and to avoid any turbidity in the dye bath.

The traditional exhaust dyeing process consumes large amounts of water and energy and produces a high level of waste effluent. The cold pad batch dyeing process uses less water, energy, and chemicals than conventional exhaust dyeing, and it can produce a comparable colour value and physical properties to that of the exhaust process. However, the cold pad batch dyeing process still requires careful monitoring of processing parameters to ensure that the centre to selvedge shade variations are within acceptable limits. In addition, it is crucial to select the correct reactivity of the dyestuff to ensure good performance.