Source: New Cloth Market
Total wet chemical processing of jute has been carried out at ambient temperature starting from bleaching to dyeing with reactive dyestuff. Ambient temperature bleaching produces satisfactory whiteness and spent bleach liquor has been reused for bleaching of another batch of fibre.
Conventional hot hydrogen peroxide bleaching and subsequent dyeing of jute with reactive dyestuffs has also been done to make a comparison with the ambient temperature processed fibre. It has been found that whiteness Index produced by ambient temperature process is slightly lower than that produced by conventional hot hydrogen peroxide bleaching but sufficient enough for carrying out dyeing in light shades and the dye affinity is always more in case of bleached fibre produced by ambient temperature process using hydrogen peroxide as bleaching agent.
So, it saves a lot of precious resources like thermal energy and water. The water effluent is also minimum resulting the process an eco-friendly one.
Need For Chemical Processing Of Jute
Any product, whether it is diversified and value added jute product like upholstery, apparels, furnishing textiles etc. or jute fabric for packaging, must have attractive look for customers' attraction. So, bleaching and subsequent colouration of bleached jute fabric in different shades, in a simple, cost effective and environment friendly way, is a challenge.
NIRJAFT has developed several processes relating to pretreatment, bleaching and dyeing of jute. Bleaching and dyeing of jute at ambient temperature is one of them.
Need For Ambient Temperature Process
- Processing of jute is difficult due to its complex chemical structure
- Bleaching of jute is done in such a way that it produces sufficient whiteness without damaging fibre
- Dyeing process is also selected in such a way that it does not damage the fibre and at the same time results in optimum fastness and dye uptake
- Jute being bulky and hygroscopic, requires a considerable amount of water and thermal energy for its processing and subsequent drying
- Effluent released after processing creates water pollution
Considering the resource management issues involved in jute processing, including the ease of processing in small operations, this study is focused on performing both bleaching and dyeing at ambient temperature without using thermal energy or sacrificing product quality.
Ambient Temperature Bleaching Process
The possibility of bleaching of jute at ambient temperature has been explored using sodium persulphate as peroxygen booster. The process is dependent on four variables Le. hydrogen peroxide, sodium hydroxide, sodium silicate and sodium persulphate, which has been optimised by using the statistical technique, central composite rotatable plan (CCRP).
A recipe using 90 gpl of hydrogen peroxide, 25 gpl sodium hydroxide, 20 gpl sodium silicate, 7.5 gpl sodium persulphate, 10 gpl non-ionic surfectant and 0.5 gpl magnesium sulphate is suggested to obtain an acceptable level of whiteness without affecting the strength.
The method involve padding the fabric in the solution using 100% wet pick up and then batching for 2 hours followed by washing.
Dyeing Of Jute at Ambient Temperature
Cellulose is the main component in jute which participate in the dyeing of jute fibre. So, all the dyes which are suitable for dyeing of cotton fibre can be used for jute with some modification.
Considering both the fastness of colour and cost of dyeing, reactive dyes are found to be best for jute dyeing. It was found after extensive study that dichlorotriazine and vinyl sulphone reactive dyes can be applied judiciously on jute fibre at ambient temperature.