Study On The Synthesis And Properties Of Waterborne Polyurethane Fabric Finishing Agent

Waterborne polyurethane is a new system which is dispersible in water medium instead of organic solvent.It has high cohesive energy,great adhesion and outstanding toughness combined with good flexibility for the urethane bond,urea bond and ionic bond in its molecular;and its properties can be improved by changing the length of soft segment and the ratio of hard and soft segments.Besides,it has advantages of innocuity,incombustibility,low odor,environmental friendliness,energy conservation,security,convenient operation processing and good breathability of film.The polyurethane-based textile finishing agent,paint,adhesives and other products are widely used in home and abroad.Recently,most polyurethane products are still solvent-borne.The organic solvents are easy to be inflammable,explosive,volatile,and air pollution is caused.The rising price of organic solvent and the strict limitation of using organic solvent and discharging waste from environmental protection department are leading to the replacement of solvent-borne polyurethane.The high quality and good properties of aliphatic waterborne polyurethane are more and more popular.A series of polyether-polyester mixed waterborne polyurethane emulsions and pure polyether or polyester waterborne polyurethane were prepared from hexamethylene diisocyanate(HDI),Poly 1,4-butylene adipate glycol(PBA),polypropylene oxide glycol(PPG), dimethylolpropionic acid(DMPA),N-methyl diethanolamine(N-MDEA) and Bisphenol A(BPA).And then film on the glass coated with Teflon,and finishing cotton fabric by impregnation. The property of the WPU emulsion,the mechanical property of the WPU film and the anti-wrinkle performance of the finished fabrics were investigated.The experimental data showed that:The activation energy in the reaction of aromatic ring chain-extender with HDI is higher than its in the reaction of PBA or PPG with HDI;but under the same temperature,the chemical reaction rate constant of HDI with BPA is smaller than that of PBA or PPG with HDI; As the polyeaster content of polyether-polyester mixed polyurethane increased,the WPU emulsion changed from translucent to milk-white,and the stability of the WPU emulsion decreased slightly;With the increase of polyeaster content,the stress at specified strain of PBA/PPG mixed WPU film increased,and the stickiness of the film was improved;The breaking stress and the breaking strain of the mixed WPU film were very low,but the breaking strain of the WPU film with pure polyether or polyester soft segment is much higher;After cross-linking by the crosslinker,the stickiness of the film was improved;The breaking stress of the PBA/PPG mixed WPU film with low polyeaster content increased,while the breaking strain of that decreased;The breaking stress and breaking strain of PBA/PPG mixed WPU film with high polyester content decreased;As the molecular weight of soft segment increased,the breaking stress and breaking strain of the WPU film with pure polyeaster soft segment increased,but the breaking stress and breaking strain of the WPU film with pure polyether soft segment decreased;The stickiness of the TDI-WPU film is much better than that of the HDI -WPU,but the TDI-WPU film was easy to turn yellow during application,and the film felt hard as the molecular of the soft segment was lower;With the increasing concentration of finishing agent,the flexible recovery angle of the finished fabric increased;The finishing effect of the cation-WPU is better than that of the anion-WPU under the low concentration of finishing agent; The finishing effect of the HDI-WPU is better than that of the TDI-WPU;The finishing effect of the PPG-WPU is better than that of the PBA-WPU.