Study On Structure And Properties Of ECDP Fibers With Low Boiling Shrinkage And Dyeing Temperature

Regenerated cellulose fabrics have been widely used for their better comformability anddyeing performances. However, regenerated cellulose fabrics also expose inevitably somedefects such as winkle, poor mechanical performance and abrasive resistance after washing.Therefore, during production processes, some kinds of fibers with better mechanicalperformances such as polyester fibers ususally are consider to be blended with regeneratedcellulose fiber to improve the overall performance of fabrics. However, polyester fibersusually are dyed in high temperature pressure, the dyeing condition does not match with theregenerated cellulose fibers’.ECDP fiber is a kind of modified polyester produced by adding the third monomer called1,3benzene2formic acid pairs between hydroxyl ethyl-5-sulfonic acid sodium(SIPE) orbenzene2formic acid ester between2-5-sulfonic acid sodium（SIPM）and the fourth monomerpolyethylene glycol（PEG）during the polymerization of PET. The aim of sulfonic group ofthird monomer added is to supply dye sites of negatron for cationic dyestuff. The aim of fourthmonomer with flexible chain added is to improve the activity of macromolecular inamorphous area, so ECDP fibers can be dyed with cationic dyestuff under low temperatureand atmospheric pressure. The compatibility between ECDP fibers and regeneratedcellulose fibers improve the durability of fabrics, reduce the cost of production and getbright-colored appearance.. Therefore, ECDP fibers can not only play an excellentreplacement role, but also boasting good economic and practical value.However, the boiling shrinkage of normal ECDP fibers is much higher than that ofregenerated cellulose fibers，which affects the appearance of the fabrics owing to differentshrinkage rate under humidity-heat treatment when ECDP fibers are blended with cellulosefibers. In view of this problem, a hot stretching processing process (FDYâ†'Roller1â†'HotDishâ†'Hot Plateâ†'Cold Dishâ†'Networkâ†'Windingâ†'Finished Product) is added into theproductive processof ECDP to reduce the boiling shrinkage. In order to reach the level ofcellulose fiber’s boiling shrinkage for ECDP fibers, Strict processing parameters are controlled. A new kinds of ECDP fibers with low boiling shrinkage rate is developed, which can be dyedunder low temperature.Through multiple experiments, the final processing parameters of hot stretchingmodification processing are obtained as follows: hot dish100-220℃, the rate of hot dish350~650m/min; hot plate temperature:180~200℃and the drawing ratio:1.01~1.20.As shown in this research, aggregation structure of ECDP fiber was changed bymodification of hot stretching. The mass crystallinity of the fibers is improved greatly, thedimension of crystallite is bigger than before with orientation improved slightly. Crystallineregion and amorphous region are mutually concentrated with the latter much loose in structure.Under the aggregation structure, moisture regain of ECDP fibers reduce slightly, and thebreaking strength and initial modulus reduce with improved breaking elongation and expandedbirefraction.In the study of fiber thermal property, the glass transition temperature and melting pointof ECDP fibers before and after hot stretching show not much change and the heat stability ofECDP fibers by TGA, do not have obvious changes. After alkali deweighting treatment, ECDPfibers are found to have bigger deweighting ratio after the modification through hot stretchingand lower alkali resistance. So, in the practical processing process, the condition of alkalideweighting should be paid attention in case of bring damage to the mechanical capacity in thepractical processing process.By dyeing ECDP with X positron and SD positron, the dyeing rate of ECDP fibers afterthe modification by hot stretching is found to increase with dyeing saturation value added, andK/S value is improved, in addition, the colorfastness of modified ECDP fibers to washing canreach level4.This research shows that, the modified ECDP fibers with low boiling shrinkage can bedyed under low temperature and atmosphere pressure, which could reach the level ofregenerated cellulose fibers’. At the meantime, the dyeing properties can be improved and themechanical properties do not reduce too much, therefore, this is a kind of chemical fibersboasting favorable exploitation and application prospects.