Synthesis And Application Of Wet Rubbing Fastness Improver For Reactive Dyes Based On Biological Substrates

Reactive dyes is a class of dyes combined with fiber by covalent bonds,with the advantagesof complete chromatography,bright color,simple process,good diffusibility and good levellingproperty.But wetting rubbing fastness of dyed fabrics is poor due to its hydrophilicity especially incase of dyeing deep color,the wet rubbing fastness can only reaches2grades and fails to meet thedemand of national standard18401.This problem has severely restricted the export and domesticsales of textiles.Therefore,how to improve the wet rubbing fastness of textile dyed by reactivedyes has become a major challenge persecuting current dyeing industry.The wet rubbing fastnesscan increase0.5~1grade by selecting appropriate color fixing agent.But the traditionaldicyandiamide fixing agent has been replaced by non-formaldehyde fixing agents due toformaldehyde emission problems.The new fixing agents,such as polyamines and polycationicfixing agents,will affect the light and chlorine resistance,and can not effectively improve the wetrubbing fastness of fabric.In recent years,waterborne polyurethane,with the advantages offormaldehyde-free,environment protecting,excellent permeability,has become a research hot spot.Waterborne polyurethane,with water instead of organic solvent as the main dispersionmedium,has the advantages of environment protection,low costs,and it has been widely used inadhesive,leather finishing agent,painting,fabric coating agent.Most of the oligomer polyols used in the synthesis of waterborne polyurethane are polyester polyols and polyether polyols,which aremostly derived from petroleum resources.With the oil resource exhausting and the relevant lawsand regulations improved steadily,environmentally friendly waterborne polyurethane hasgradually become the trend in research and development.Vegetable oil,one kind of natural oil,hasthe advantages of a wealth of sources,renewable,low costs,etc.including linseed oil,castoroil,soybean oil,etc.In this research,prepolymer was first synthesized by IPDI and castor oil which acted asoligomer polyols,and then the waterborne polyurethane emulsion based on castor oil wassuccessfully synthesized by the hydrophilic chain-extender reaction,neutralization reaction,chainextension reaction,blocking reaction and emulsification process.The structure and properties ofemulsion and film were characterized by FT-IR, and particle size analyzer,Viscosity,stabilitytesting,and mecha-nical properties were tested as well.The results indicate the optimal synthesisprocess are: n(-NCO)/n(-OH)=2.3（78℃,3h）,8%wt.%of DMPA prepolymer, n(triethylamine)/n(-NCO)=0.15,n(NaHSO3)/n(-NCO)=0.11.The synthesis WPU based on castor oil was used toincrease the rubbing fastness of cotton fabric dyed by reactive dyes,The finishing process wasstudied.The results indicated the optimal finishing process were:the amount of waterbornepolyurethane fixing agent was40g/L,baking temperature was130℃,baking time is3min.Underthe optimal condition,the wet rubbing fastness could increase1.5levels and reached4levels.Inaddition,solid color performance and solid color process of home-made waterborne polyurethanefixing agent were compared with the commercially available non-formaldehyde fixing agent,andthe results indicated that the fixing performance of home-made waterborne polyurethane fixingagent were better,and has smaller effect on fabric shade.what’s more,the home-made WPU hasadvantages of energy saving and environment protection.In addition,in this research,soybean was used as raw material,under acidic conditionexpoxidized soybean oil (ESO) were prepared through the epoxidation with hydrogen peroxide.The prepared ESO was then used as raw material,by the process of ring-opening with lacticacid,the soybean oil polyols modified by lactic were obtained and the hydroxyl value was140mgKOH g-1.The waterborne polyurethane fixing agent of reactive dyes wassynthesized with soybean oil polyols (self-made),isophorone diisocyanate(IPDI),dimethylol propionic acid (DMPA) as raw materials and NaHSO3as blocking agent by acetone method. Effects of R value and DMPA content on the properties ofsynthesized product were investigated by FT-IR, particle size, viscosity, and stabilityof the emulsion test.The results showed the optimum synthesis conditionswere:n(-NCO)/n(-OH)=1.2,5%(based on the weight of prepolymer) of DMPA.Thesynthesized WPU was then used as fixing agent of reactive dyes, and the applicationconditions were studied, and the optimum fixing process is:the optimum amount ofWPU fixing agent is60g/L and the best curing temperature is140℃.Under theoptimal conditions,the wet rubbing fastness could increase1.5grades and reachedlevel4.