Pad roll and continuous bleaching process in textile:
Table of Contents
Pad-roll bleaching process:
Fabrics can be bleached in two ways using the pad-roll method
(1) Cold batch
(2) Hot batch
An amount of bleaching liqueur for making cold and hot batches is given below.
Recipe:
Sodium silicate 2 kg
Sodium carbonate 0.5 kg
Sodium hydroxide 0.4 kg
Or, hydrogen peroxide (35%) 3.8 liters
Hydrogen peroxide (50%) 2.5 liters
Wetting agent (as required) 0.4 liters
Water 94 liters
(1) Pad roll and continuous bleaching process in textile-Cold batch:
The fabric is wetted inside the Impregnation tank where the bleaching solution is kept using a roller. Here the cloth is bleached by a liqueur of hydrogen peroxide. The cloth is then squeezed by a squeezing roller and stored in the form of a roll for 12 hours. The fabric is covered with polythene so that it is not damaged. The fabric is washed after the bleaching is finished.
(2) Pad roll and continuous bleaching process in textile-Hot batch:
Bleaching action is very good in the hot batching method, its bleaching ability is much higher. There are impregnation tanks, steamers, and mobile batch chambers. The heating batching chamber is a separate unit that rests on wheels. When filled with bleached cloth, the padding is treated with manganese hydrogen peroxide solution, then squeezed and placed in a pre-heating box.
Fabrics from the heating box are deposited in the mobile batch chamber. Thus when one batch is finished another batch is deposited in the new batch chamber. Thus many chambers are filled with cloth and kept in stock for a certain period. In stock, the fabric is rotated with a machine to prevent uneven bleaching. To keep the temperature inside the chamber just right Steam is run at a slow speed.
Continuous Bleaching Process:
Recipe:
Sodium silicate 15 Pounds
Caustic Soda 2 Pounds
Hydrogen peroxide (35%) 1.5 gallons
Magnesium sulfate 0.2 Pounds
Water 96 gallons
pH 10.9
Bleaching can be done in a very short time with the help of this process. This is a modern method. Continuous bleaching is done by non-stop bleaching through J-Box. A J-box is a box similar to the English letter (J) that is made of stainless steel or ceramic.
J-Box is used commercially for continuous bleaching in the textile industry. The cloth is inserted over the J-box and taken out from the bottom after the bleaching process is over. The production capacity of J-Box can be from 8 to 40 tons per day. Scouring and bleaching can occur simultaneously with J-Box.
Bleaching is done in three steps through J-Box.
1. Dyeing the product with impregnation or bleaching liqueur:
Impregnation or dipping of wet cloth scoured in the bleaching solution made from the mentioned ingredients at a temperature of 70°C. The cloth is then squeezed by a squeeze roller and taken to the J-box.
2. Storage of fabric in J-box:
Impregnated fabric in bleaching liqueur is steamed in J-box at a temperature of 93°C to 99°C for 60 minutes to 90 minutes. As a result, bleaching continues.
3. Washing:
The cloth is then washed first with hot water and then with cold water.
