Optimization Of Dyeing Process For Cationic Coating Of Denim And Its Influence On Heat And Moisture Comfort

Pigment dyeing is an innovative technology which can be conducive to establish a good ecological environment. It has many advantages, such as clean production, energy and materials saving, quality and performance improving, special style of fabric, ect. Pigment dyeing is use of electrostatic attraction between opposite charges. Cotton fabric or cotton blended fabric need to be modified in traditional pigment dyeing to make the fiber wear electropositive to adsorb negatively charged coating. But cationic pigment dyeing needs not cationic pretreatment of fabric. It can use cationic coating and anionic on the surface of the cellulose fibre by electrostatic force directly, then adhesive is used to obtain good color fastness and high performance.Cationic pigment dyeing process were studied in this paper. Firstly cationic coating named CD-112and adhesive named ZW-859were optimized by testing performance of fabric. Next orthogonal test was designed to analysis influence factors on the K/S value and rubbing fastness, namely dyeing bath ratio, the dosage of cationic coating, adhesive dosage, pH value, dyeing temperature and holding time. And the optimal parameters were obtained through range analysis which were cationic pigment dosage15%(owf), adhesive dosage6%(owf), bath ratio1:30, dye bath pH=4-5, dyeing temperature60℃, time15～20min. K/S value and rubbing fastness of cotton yarn dyed by the optimal process were discussed. Fabric and yarn dyeing properties of using adhesive and without adhesive were compared, and the experimental results showed that adhesive had an important influence on yarn and fabric.Fabric performance, especially thermal wet comfort performance draws more and more attention, so the thermal wet comfort of cationic pigment dyeing denim fabric were also investigated in this paper. The experimental results showed that the cationic pigment dyeing had small influence on the thermal resistance and had great influence on the air permeability of fabric. The thermal resistance decreased by7.39%, which means cationic pigment dyeing increasing thermal conductivity properties of the fabric, and air permeability rate was reduced by26.9%, which means cationic pigment dyeing reducing the permeability of the fabric, and the results were analyzed in theory. Because pigment dyeing process had many influence parameters, the change of one or several parameters would cause the change of pigment dyeing fabric performance, so the artificial neural network model was established to forecast the permeability and wet resistance of the fabric. The experimental results showed that the difference between the predictive and measured values were very small, provided that the neural network was trained very well. The average absolute error of wet resistance is0.0684, the average absolute error of ventilation rate is0.6036, the average error of wet resistance estimate is2.53%, the average error of ventilation rate estimate is3.14%, and the experiment got the desired result. Therefore, we can use this network to forecast the wet resistance and permeability of cationic dyeing denim fabric under a certain condition, and it is helpful to guide production.