Research Of The Pad Dyeing With Natural Dye

With the improvement of people’s living standards,natural dye more and more get thefavour of people, because of its excellent characteristics of ecological and environmental,non-toxic harmless.So,the using of natural dye was carried out widely. Currently, researchon natural dyes was mainly focused on technology of impregnation, but pad dyeing processis relatively little research.Methods to improve the color fastness of natural dyes is mainlyusing different metal treatment agents with different processes, such as chromium, tin,copper and other metal ions. But,some metal ions have been limited due to the ecologicalproblems. In this paper, methods of pad dyeing with natural dye have been studied, and theimpact of improving the color fastness of dyed fabrics with carboxylic acids has beeninvestigated.This paper firstly test natural dye pH stability, temperature stability, light stability,redox stability and affinity, and then good stability and low affinity natural dye was chosenfor this study.Experiments showed that chestnut shell, sorghum red, red rice red, mulberryred pigments are suitable for pad dyeing research.Taking the K/S value of dyed fabric and color fastness as the basis for evaluation, westudied the processes of pad dyeing on wool and silk fabric to determine the each dye’soptimum processes. Pad dyeing on silk, the optimum pad dying processes of chestnut shell：temperature100℃, humidity100%, steaming30min. The optimum pad dyeing processesof red sorghum：temperature100℃, humidity100%, steaming30min. The optimum paddying processes of shellac red：temperature100℃, humidity100%, steaming30min. Theoptimum pad dying processes of red cabbage：temperature100℃, humidity100%,steaming40min. Pad dying on silk, the optimum pad dying processes of chestnut shell：temperature110℃, humidity100%, steaming30min. The optimum pad dying processesof red sorghum：temperature100℃, humidity100%, steaming30min. The optimum paddying processes of shellac red：temperature100℃, humidity100%, steaming20min. Theoptimum pad dying processes of tea tree fruit：temperature100℃, humidity100%, steaming40min.Using three methods of pretreatment, bath dyeing and after-treatment, this papercompared influence of ferrous, rare earth, tannic acid to color fastness. The resultsshowed,tannic acid pretreatment played a good role on color fastness and dyed fabric’scolor. Sorghum red pigment pad dyeing fabric’s K/S value can reach16.15, and its fastnessreached level4above. Shellac red pigment pad dyeing fabric’s K/S value can reach14.23,and its soaping fastness reached level2-3, but other fastness can reach level4above.Therefore, we can further develop and use tannin acid to make it play an importantrole in textile dyeing process in future.Requirements of two kinds of natural dyes for color matching pad dyeing werepreliminary studied.Choosing two dyes as color matching，and taking the K/S value ofdyed fabric and color fastness as the basis for evaluation, we determined optimal steamingprocess for color matching. Optimal steaming process of chestnut shell pigment andsorghum red pidment: temperature100℃, humidity100%, steaming20min. Optimalsteaming process of red rice red pigment and shellac red pidment: temperature100℃,humidity100%, steaming30min.