Supercritical CO2 Foaming Process of Polyurethane Bead based on Spouted Bed Technology
Xia Chengzhi, Chen Yichong, Xu Zhimei, Zong Yuan, Liu Tao, Zhao Ling
State Key Laboratory of Chemical Engineering, East China University of Science and Technology, Shanghai 200237, China
摘要：以热塑性聚氨酯为原料，超临界CO2为发泡剂，通过喷动床发泡技术制备了热塑性聚氨酯发泡珠粒，考察了CO2流速、饱和温度、饱和压力、泄压速率对珠粒发泡行为的影响。结果表明，珠粒发泡均匀性先随着CO2流速上升而上升，之后基本不变，表明形成稳定喷动后流速的提升对珠粒发泡均匀性无改善作用。珠粒发泡倍率随着饱和温度和饱和压力的提高先上升后下降，随着泄压速率的提高而提高。饱和温度的提高使泡孔密度下降，泡孔直径增大，饱和压力和泄压速率的提高使泡孔密度上升，泡孔直径下降。当CO2流速为0.012 m/s、饱和温度为150℃、饱和压力为10 MPa、泄压速率为20 MPa/s时，珠粒发泡倍率最大，达到9倍，泡孔密度为1.13×107个/cm3，平均泡孔直径为82.3 μm。
Abstract：Using thermoplastic polyurethane (TPU) as raw material and supercritical CO2 as foaming agent, TPU foaming beads were prepared by spouted bed foaming technology. The effects of CO2 flow rate, saturation temperature, saturation pressure and depressurization rate on the foaming behaviors of beads were investigated. The results show that the foaming uniformity of beads first increases with the increase of CO2 flow rate, and then remains unchanged basically, which indicates the improvement of flow rate after the formation of stable spouting has no effect on the foaming uniformity of beads. With the increase of saturation temperature and saturation pressure, the bead foaming ratio first increases and then decreases, and bead foaming ratio increases with the increase of depressurization rate. The increase of saturation temperature leads to the decrease of cell density and the increase of cell diameter, the increase of saturation pressure and depressurization rate leads to the increase of cell density and the decrease of cell diameter. When the CO2 flow rate is 0.012 m/s, the saturation temperature is 150℃, the saturation pressure is 10 MPa, and the depressurization rate is 20 MPa/s, the bead foaming ratio is largest, reaching 9 times, the cell density is 1.13×107/cm3, and the average cell diameter was 82.3 μm.
Keywords：spouted bed; supercritical CO2; bead foam; thermoplastic polyurethane; foaming uniformity
Xia Chengzhi，Chen Yichong，Xu Zhimei，et al. Supercritical CO2 foaming process of polyurethane bead based on spouted bed technology[J]. Engineering Plastics Application，2020，48(5)：63-68.