Synergistic effect of anionic and nonionic monomers on the synthesis of high solid content waterborne polyurethane

Abstract

High solid content waterborne polyurethane dispersions (PUDs) were synthesized via to the combination of ionic and nonionic monomers, in which the effect of the molecular mass of poly (ethylene glycol) (PEG) and its connection relationships of those hydrophilic groups in polyurethane with dimethylol propionic acid (DMPA) (through changed the synthetic schemes of PUDs) were researched. It is found that the molecular mass of PEG has obvious effect on combining with DMPA to synthesize PUDs. The incorporation of small molecular mass PEG200 (Mn = 200) had little effect on improving the dispersion and stability properties of anionic PUDs. But as the molecular mass of PEG increasing, they (PEG400, PEG600, PEG1000 and PEG2000) have obvious effect on improving the dispersion and stability properties, and can decrease the required dosage of DMPA to stabilize PUDs, moreover, cam improve the solid content of the latex. However, the effect of PEG2000 is less prominent than that of PEG400, PEG600 and PEG1000. The connection relationships of PEG with DMPA also have a certain effect on the property of the latex. When the small molecular mass one (PEG400) directly connects with DMPA, the synergistic effort is enhanced and the required dosage of DMPA to stabilize latex decreases to 2.0% (using DMPA alone needs 2.4%). As a result, the solid content of PUDs increased from 42% (using DMPA alone) to 52%, and the water resistance of PUDs is also improved. The thermal, dynamic mechanical and tensile-strength properties of derived films of PUDs were also analyzed, and the results show the incorporating PEG into polyurethane decrease the glass transition temperature of soft segments (Tgs), as well decreases the crystallinity and the extent of phase separation, which both cause the decrease of heat resistance. But through the combination, the synthetic formulas of PUDs with better tensile strength and elongation ratio than using DMPA alone were obtained. Besides, it is found that the molecular mass of PEG and the connection relationships of PEG with DMPA also had some influence on the properties of the derived films.