Study On The Stripping Method Of Polyester/Cotton Blended Fabric And Its Mechanism

Decoloration is indispensable in the dyeing and finishing, mainly used in three places:stripping for the fabric with dyeing defect, stripping before the reusing of recycling waste fabric, stripping in qualitative and quantitative analysis for the fiber. In accordance with the principle of similar solubility parameters, chose the dimethyl sulfoxide from many swelling agents as the swelling agent of this stripping method; From a variety of excellent organic solvent of, select DMF as solubility property stripping agent; Take thiourea dioxide as reducing stripping agent. Then respectively experiment with through a single-factor method and orthogonal experiment method for each reagent, and get the best proportion of different component. When testing, it is found that the swelling step can play the part in solubility property stripping. So this paper divided the new stripping method for PET/cotton blended fabric into TWO STEP method and THREE STEP method. The TWO STEP is swelling and reduction stripping, while the THREE STEP is swelling, solubility property stripping and reduction stripping. And the conclusion is drew as follows:(1) The optimal proportion of TWO STEP is that, taking a portion for reference, the proportion of DMSO to thiourea dioxide is16to0.004. And the best process conditions is that swelling temperature is120℃, swelling time is40minutes, the stripping temperature is100℃, stripping time is30minutes.(2) The optimal proportion of THREE STEP is that, taking a portion for reference, the proportion of DMSO to DMF to thiourea dioxide is16to14to0.02. And the best process conditions is that swelling temperature is120℃, swelling time is40minutes, the solubility property stripping temperature is100℃, solubility property stripping time is30minutes, and the reduction stripping temperature is also100℃, time is30minutes.When swelling and solubility property stripping, DMSO and DMF are also taken a physical reaction, and without and other agent, they are easily to extracted with distillation method. And the stripping rate is very good.Finally, it has been viewed the stripping mechanism. With dimethyl sulfoxide swelling for the polyester/cotton fabrics is mainly to swelling the polyester content. When Dimethyl sulfoxide molecules enter the polyester fibers, it destroy the tight structure of polyester molecular. Its volume expand after swelling, and its structure become loose, thus it is convenient for stripping agent enter the inward of fiber. The solubility parameters of disperse dyes are most in the rang [10.08,15.13], while the solubility parameters of DMF is12.1, so they are conform to the principle of similar solvent solubility parameters. In addition, they are conform to the principle of similar polarity and salvation principle. So DMF is a very excellent solvent. The mechanism of thiourea dioxide reduction stripping for the remaining dye is that the chromophores of dyes are reduced, and their structures are destroyed and decoloration.