Cold Pad Batch Research Articles

Cold Pad Batch Cationization and Dyeing of Linen Fabric with Reactive Dyes

Unmodified linen fabric is cationized through the reaction of two different commercial cationizing agents, 3-chloro-2-hydroxypropyltrimethyl ammonium chloride (CHTAC) and polyaminochlorohydrin quaternary ammonium salt with epoxide functionality (PAQAC). Uncationized and cationized linen fabrics are dyed with four different types of fiber reactive dyes by using the cold pad batch dyeing method. The fastness properties of the dyed cationized linen fabrics have been evaluated.

Cold Pad-Batch dyeing method for cotton fabric dyeing with reactive dyes using ultrasonic energy

Reactive dyes are vastly used in dyeing and printing of cotton fibre. These dyes have a distinctive reactive nature due to active groups which form covalent bonds with –OH groups of cotton through substitution and/or addition mechanism. Among many methods used for dyeing cotton with reactive dyes, the Cold Pad Batch (CPB) method is relatively more environment friendly due to high dye fixation and non requirement of thermal energy. The dyed fabric production rate is low due to requirement of at least twelve hours batching time for dye fixation. The proposed CPB method for dyeing cotton involves ultrasonic energy resulting into a one third decrease in batching time. The dyeing of cotton fibre was carried out with CI reactive red 195 and CI reactive black 5 by conventional and ultrasonic (US) method. The study showed that the use of ultrasonic energy not only shortens the batching time but the alkalis concentrations can considerably be reduced. In this case, the colour strength ( K/ S) and dye fixation (%F) also enhances without any adverse effect on colour fastness of the dyed fabric. The appearance of dyed fibre surface using scanning electron microscope (SEM) showed relative straightening of fibre convolutions and significant swelling of the fibre upon ultrasonic application. The total colour difference values Δ E (CMC) for the proposed method, were found within close proximity to the conventionally dyed sample.

Cold pad–batch bleaching of cotton fabrics with a TAED/H2O2 activating system

The cold pad–batch bleaching of cotton fabrics using a tetra acetyl ethylene diamine/hydrogen peroxide (TAED/H2O2) activating system is investigated in this study. The effects of key bleaching parameters (hydrogen peroxide dosage, sodium hydroxide dosage, TAED/H2O2 mol ratio and batch time) on the bleaching efficiency were investigated by single‐factor analysis and orthogonal experiment analysis. The performance of the activator TAED in the cold pad–batch process was examined and the activating mechanism is discussed. The optimised bleaching recipe and processing conditions are reported, and the optimal activated bleaching process is also compared with a conventional cold pad–batch bleaching process. The results show that the optimised TAED/H2O2 activated bleaching system could achieve high quality cotton bleaching with comparable fabric whiteness to the conventional system at much shorter batch times, and with significantly reduced fabric strength loss and decreased alkali consumption, which would be beneficial to sustained development of the textile wet‐processing industry.

Research in the cold pad–batch dyeing process for wool pretreated by hydrogen peroxide

Research in the cold pad–batch dyeing process for wool pretreated by hydrogen peroxide

Pre-cationization of cotton fabrics: An effective alternative tool for activation of hydrogen peroxide bleaching process

Hydrogen peroxide is a well-known environmentally safe bleaching agent for cotton fabric. However, bleaching of cotton based fabric with hydrogen peroxide requires alkaline medium (normally NaOH), stabilizer and either high temperatures or long dwell times. After bleaching and before dyeing, large amount of water is required for washing the residual un-decomposed hydrogen peroxide and the residual alkali. In this work, a new approach for bleaching cotton based fabric is postulated and investigated. The cotton fabric was scoured and cationized with NaOH and 3-cholor-2-hydroxy propyltrimethyl ammonium chloride (commercially known as CR-2000) either concurrent in one step process or separately in two step process. The scoured and cationized cotton fabric was then preceded for hydrogen peroxide bleaching. The cationic group on the cationized cotton fabric serves a dual function in the bleaching bath; the first is built-in catalyst for bleaching process and the second is powerful alkali site necessary for activation of hydrogen peroxide bleaching bath instead of NaOH. Three bleaching technique are utilized in bleaching of pre-scoured and cationized cotton fabric. These techniques are, exhaustion technique, pad-steam and cold pad-batch. The effects of cationization level, bleaching technique, bleaching parameters were systematically investigated. The fabric was monitored for strength properties, whiteness index and nitrogen content before and after the bleaching process. Results obtained show that, pre-cationization of cotton fabric provide comparable fabric whiteness in all technique investigated at much shorter reaction times and lower bleaching temperature in absence of NaOH. These results call for a breakthrough not only in bleaching of cotton based textiles but also in conventional detergent washing formulation.

Impregnation and Exhaustion Bleaching of Cotton with Peracetic Acid

Cotton fabric was bleached with equilibrium peracetic acid in an exhaustion process and in cold pad-batch, hot pad-batch, and pad-steam bleaching processes. Exhaustion bleaching proceeded for 40 minutes at 60 °C and pH 7.5 with different concentrations of Persan S15 (peracetic acid produced by Belinka, Slovenia). Pad-batch processes were conducted with storage for different times at room temperature or at 60 °C. Two bleaching baths with 15 and 60 ml/l of Persan S15 were used for the impregnation processes. Pad-steam bleaching was also performed; the samples were steamed immediately after padding with bleaching solution or after cold/hot storage. The degree of whiteness achieved with elongation of storage time was measured. The influence of different bleaching conditions on damage to the cotton fabrics was evaluated by measurements of the degree of polymerization and the breaking strength of the fabrics. It was established that the achieved whiteness values depend on the concentration of the bleaching agent, temperature, and time of treatment. The exhaustion bleaching and both types of pad-batch bleaching with low concentration bleaching solution are very convenient processes for bleaching of cotton fabric with peracetic acid. The pad-steam process did not prove appropriate. The breaking strength of the fabric did not deteriorate remarkably with any of the processes, but the degree of polymerization of the fibers revealed that damage occurred at high concentrations of bleaching agent.

Research in the cold pad–batch dyeing process for wool pretreated by hydrogen peroxide

The cold pad–batch dyeing process of wool pretreated by hydrogen peroxide was carried out with Lanasol reactive dyes and Realan reactive dyes. The influences of various conditions of the dyeing process, including urea dosage, sodium bisulphite dosage, pH value, batching time and the liquor pickup on colour yield, were analysed. Fixation, levelness of dyeing, dye penetration, colour fastness, breaking strength and elongation were compared between untreated and treated wool fabrics. The study showed that cold pad–batch dyeing of wool fabric is a good prospect for future use because of the resulting advantages, such as higher fixation yield, less energy usage and lower sewage discharge.

New Remazol ® Ultra RGB technology for reduced lead times and higher productivity

Today's market drivers focus on reduced lead times to support speed to market, higher productivity and elimination of non-conformance for cost effectiveness. The reactive dye technology should be flexible for application by exhaust, cold pad batch (cpb), and continuous dyeing equipment. The new Remazol Ultra RGB dyes designed for deep saturated shades, have outstanding build-up with near perfect compatibility in ternary combinations leading to the development of shorter dyeing processes for exhaust application, whilst delivering an excellent laboratory to bulk and inter-bulk repeatability for all dyeing processes. The innovative chemistry also delivers resistance to washdown after multiple wash cycles in modern activated detergents, and minimal photochromism and colour inconstancy between different light sources - an increasingly important criteria for retailers and brands.

New developments in cold pad batch dyeing

The classic cold pad batch dyeing process (cpb) has undergone significant changes since its development during the early sixties and is a culmination of good co-operation between dyestuff producer, dye-house and machine manufacturer. In addition, leading retailers such as Marks & Spencer have provided challenges in respect of new fabric constructions, emerised fabrics and fastness requirements which have given impetus regarding this specific dyeing technology. In this review we will demonstrate the importance of reactive dyestuff diffusion and its significance in producing a superior fabric with better wash and wear fastness performance on both non-surface finished and emerised material.

Development of a one‐stage process for pretreatment and cationisation of cotton fabric

A one‐stage process for cationisation and pretreatment of cotton fabric was developed. Cationisation of cotton cellulose was carried out with 3‐chloro‐2‐hydroxypropyltrimethylammonium chloride, whereas pretreatment comprised enzymatic and oxidative desizing, scouring, bleaching with hydrogen peroxide, combined desizing and scouring as well as combined desizing, scouring and bleaching. Each of these pretreatment operations or their combination with and without cationisation was carried out using three techniques, namely, cold pad–batch, pad–steam and exhaustion. It was found that the cationisation chemicals were compatible with the scouring ingredients and, to a lesser extent, with the formulation of enzymatic desizing. On the other hand, cationisation chemicals were not compatible with oxidative desizing or peroxide bleaching ingredients. Efficiency of the one‐step process for scouring and cationisation was maximised through detailed investigation of the process parameters. The treated fabric can be dyed without electrolyte and the fabrics show a high levelness of colour shade, residual wax content and nitrogen content.

Evaluating Hydrogen Peroxide Bleaching with Cationic Bleach Activators in a Cold Pad-Batch Process

Bleach activators generate peracids in the presence of hydrogen peroxide and alkali that are more potent oxidizing agents than hydrogen peroxide under comparable bleaching conditions. The effects of key bleaching parameters (activator concentration, hydrogen peroxide, chelant, and pH) on the performance of cold pad-batch bleaching on cotton are investigated. Optimized recipes are determined for two cationic activators, N-[4-(triethylammoniomethyl) benzyl]ca prolactam chloride and 6-( N,N,N-trimethylammonio) hexanoyl caprolactam p-toluenesulfo nate, using a central composite experimental design. The laboratory optimized conditions are used for pilot plant scale bleaching of cotton knit fabric. CIE whiteness index values are calculated from measured reflectance data of the pilot scale bleaching and are in close agreement with those predicted by the experiment. A high level of whiteness ( CIE WI > 70) is achieved for both activators with 8-hour batching, and measurements of the degree of polymerization of the bleached and greige fabrics show little fiber damage in each case.