Studies On Synthesis Of High-solid-content Polymer Polyols

Polymer polyol (POP) are stable dispersions of glassy polymers in polyether polyols. In this work, the POP with high solid content of 45% were prepared by dispersion copolymerization of styrene (St) and acrylonitrile (AN) in polyether polyols with polyether meilate-type macromonomer as stabilizer precursor in semi-batch, single- reactor and two-reactor continuous and seeded-batch processes. The stability and viscosity and the distribution of particle size of POP were studied. For the purpose of improving the stabilizing ability of the macromonomer for the POP, various macromonomers were synthesized by reacting various polyethers with maleic anhydride at different temperature, and evaluated for their stabilizing abilities. The results showed that the functionality and molecular mass of macromonomer were the crucial factors for their stabilizing ability.. Therefore, a novel macromonomer with four functionality was synthesized. The effects of polymerization parameters on stability and viscosity of POP were investigated in semi-batch, seeded-batch and continuous processes, respectively, while the corresponding particle shape and size distribution were determined by SEM and laser grading analysis. The results indicated that the polymerization in both particle phase and disperse phase played important roles on the stability and particle number of POP. And that the particle size and distribution were the key factor for controlling the viscosity of POP, wide particle distribution can low the viscosity of POP, while small particles increasing the viscosity of POP. So POP with low viscosity can be obtained in both two-reactor continuous and seeded-batch process, which can produce POP with large particle size with wide distribution. By optimizing, the POP with solid content of 45% and viscosity of 4700mPa.s was obtained. The polymerization mechanism of continuous process was studied. The result indicated that there was the phenomenon of neculation in the second reactor in two-reactor continuous process. The phenomenon can increase the viscosity of POP. So the key factor in two-reactor continuous process was the reducing of neuclation in the second reactor.