Synthesis Of Waterborne Polyurethane And Its Application In The Anti-Crease Finishing On Cotton Fabric

In this paper, series of waterborne polyurethane were successfully prepared by pre-polymerizing—blocking—extending—dispersing. Study was set about from the determining the raw materials such as polyol, isophorone diisocyanate(IPDI), dimethylolpropionic acid (DMPA) etc. The effects of different kinds of polyols, DMPA content, the extent of neutralization, different blocking agents and synthesis process on WPU properties had been studied. Blocking process by 2-butanone oxime (MEKO) had been investigated, the agent with good dispersion had been prepared, and WPU formula had been optimized by orthogonal method and formulation experiment.The result showed that: The conditions were appropriate when the pre-polymerizing temperature was 90℃, the pre-polymerizing time was 2h, and the neutralization temperature was 50℃. Neutralization could be help to carry out the reaction after the completion of pre-polymerizing. Mass ratio of DMPA should be around 5 percent and the extent of neutralization should be 90% to 100%. Then such performance as film-forming, stability of the waterborne polyurethane obtained from two different blocking agents NaHSO₃ and MEKO were discussed. The product which was blocked with NaHSO₃ had excellent film-forming property and the product which was blocked with MEKO had excellent stability. When n(H)/n(-NCO) was 1:1 to 1.2:1, the temperature and total time of the blocking reaction was 80℃and 5h, the blocking efficiency was high. Some factors such as varieties of polyols, ratio of isocyanate to polyol and the chain-extender were considered through orthogonal method. From the method we got that the product which was synthesized with polyether 220 had better water resistance and the product which was synthesized with PTMG2000 had better mechanical properties. The waterborne polyurethane would have excellent comprehensive properties when the ratio of polyether 220 and PTMG2000 was 3:1.The finished cotton fabrics had been analyzed by FTIR and EMS and the process of WPU anti-crease finishing had been studied. The main results obtained were as follows: A certain degree of chemical cross-linking occurred between WPU and cellulose. The WRA of the finished cotton fabric with WPU increased more than 60°and the strength retention rate reached 90%, other properties had no effect when the concentration of finishing agent was 100g/L, curing conditions was 160℃/ 3min. It was appropriate that when the recruitment of WPU was 40g/L in the compound of 2D Resin, the WRA and strength retention of the finished fabric were increased. When the ratio of WPU and BTCA was 1:1 (total finishing agent was 100g/L), the WRA was lower than the one finished by BTCA. But the strength retention was much higher, which could reduce the capacity of the BTCA, environment pollution and cost.In general, traditional anti-crease finishing agent will release formaldehyde during the finishing process and in the course of the storage and wear of the cotton fabrics. It not only pollutes the environment, but also does harms to the people's health. The strength loss of these finished cotton fabrics is serious as well. The WPU prepared proved to be an excellent non-formaldehyde and low strength-loss anti-crease agent, which would have a great potential market in future. It's no doubt that its application in the textile finishing will benefit both economy and society.