Synthesis And Application Of Water-borne Polyurethane Fixing Agent B

Reactive dyes have the advantages of full colors, bright colors, and convenience of use. They are therefore the preferred dyes for dyeing cellulosic fibers. But their fastness is usually unsatisfactory especially the wet crocking fastness which is only 1～2 grade. With the development of economy, the demand for the wet crocking fastness is getting higher and higher which is generally required level 3 or above. This requirement is very difficult to fulfill especially for those deep color fabrics. So how to resolve the problem of poor wet crocking fastness of dyed fabrics has become the hot research topic for the dyeing and finishing industry.The object of this research is to synthesize a waterborne polyurethane wet crocking fastness improver (wet crocking improver B) and apply the desired product to dyed fabric by padding-drying-baking process so as to enhance the wet crocking fastness of the dyed fabric. The desired product is synthesized by using mainly the chemicals of diphenylmethane diisocyanate (MDI) and polyethylene glycol (PEG). The synthetic process is determined as follows: R (the value of MDI/PEG) = 1.35; molar percent of dimethylol propionic acid (DMPA) in the prepolymer 7%; mass percent of diethylenetriamine (DETA) in the prepolymer 7.35%; molar proportion of diethylenetriamine to epichlorohydrin 1:2. The pre- polymerization temperature is 100℃and the time is 2.5h. The chian extending reaction temperature is 100℃and time is 30min. The modifing reaction temperature is 100℃and the time is 2h.The application process of wet crocking improver B is determinded as follows: one dip one rolling (improver B 50 g / L, pH 7～8, pad-pickup 100%)→dry (100℃)→baking (130℃, 90s)The application results show that when the fabric is finishied by wet fastness improver B, the wet rubbing fastness is enhanced 1.5 grade or above.The innovation of this project is that we make the MDI which used to be applied in the synthesis of solvent-based polyurethane be used in the synthesis of waterborne polyurethane fixing agnet and found a new way for the MDI in the application of waterborne polyurethane.