The Mordanting Of The Rare Earth In The Dying Of Natural Dyes On Silk

As well as enhancing the environmental awareness and the importance to human health, people pay more attention to the development and using of natural dyes.Comparing with synthetic dyestuff,natural dye is nontoxic,harmless,no pollution and could be degraded biologically well. At the same time,the fabrics dyed with natural dyes has natural flavor and healthy functions. According to the uncertainty of dye pigment,the fabrics dyed with natural dyes is much more natural,naive and elegance.On the other side,silk is soft,plump,fluffy and has pearl -like gloss surface,so it is used as high-grade garment materials and materials for underwear,nightclothes and so on.So,it has a much higher requirement for dyes,and dying silk with natural dyes has wide application prospect.Due to the production of natural dyes need to go though a complex process of purification, the application of natural dyes is high-cost,so we use the low-cost food colour instead of natural dyes to make experiments.Prevalence of poor color fastness of natural dyes,dyeing when the use of alum,ferric,and other traditional media for heavy mordant dye,which has also brought a number of environment problems.As a result,the use of rare earth as a new kind of mordant,can improve the fastness of natural dyes at the same time resolve environmental pollution problems. The rare-earth elements are representative metallic elements,their metal lively is next only to alkali metal and the alkaline earth metallic elements,but more lively than the other metallic elements.The rare earth ion make a combination combining with the base group such as -OH, -N=N-,-SO₃²⁺,which make the rare earth applying to printing and dyeing industry.This topic choosing the rare earth as the mordant of the natural dyes on silk is to increase color depths,level dyeing etc,at the same time,to a certain extent,be able to raise the kind of color fastness. The results indicated that,due to the different structure of the dye,these five natural dyes (include gardenia yellow,lac red,safflower yellow,gardenia blue and natural black ) have different stability in different pH values,and the different dye-uptake curves of equilibrium and leveling properties of natural dye,The lac red has poor stability in acid and alkaline conditions, and vulnerable to changes in color lights.Safflower yellow is better and the kind of gardenia dyes are the best.In the rare earth into the role of the media,lac red dye into the role of the media is the most obvious.The lac red was applied to mordanting before dyeing,and the amount of dyes is 1%(owf),adding rare earth Ce₂(CO₃)₃,whose dosage is 0.8%(owf),the rate growth of dyeing percentage is 57.16%,and K/S values is 52.61%,compared with no rare earth.This indicate that lac red has more unit structure which can complex with the rare earth.The thesis also make experiments about the best dyeing method of gardenia yellow,safflower yellow,gardenia blue and natural black,and find that addition of the rare earth could significantly enhance the apparent depth of K/S value of the natural dyes on silk,at the same time be able to improve the relevance of fabric color fastness,and has been better dyeing effect.This article studies the dyeing of natural dyes on silk by using of the rare earth,and receives fairly good effect,it provides an important reference value for application.