热可逆型热塑性聚氨酯的合成与性能研究

Study on synthesis and properties of thermal reversible type thermoplastic polyurethane

采用含双官能度酚羟基的BPA[2,2-二(4-羟基苯基)丙烷]对MDI(二苯甲烷二异氰酸酯)预聚体进行扩链,制备了热可逆型BPU[BPA扩链TPU(热塑性聚氨酯)]。采用红外光谱(FT-IR)法实时跟踪—NCO基团的变化对BPU的解封行为、解封后的再封闭行为等影响。研究结果表明:—NCO基团的解封速率随温度升高而增大,在降温过程中可发生—NCO基团的再封闭反应;初始解封温度越高,再封闭的反应速率越快,并且反应达到平衡时所需的时间越短;BPU的高温熔体流动性随恒温时间延长或BPA掺量增加而增大,并且熔体流出量的增加速率随R[R=n(—NCO)/n(—OH)]值增加呈先小后大态势。

With phenol hydroxyl containing bifunctional BPA[2,2-bis（4-hydroxy phenyl） propane] as chain extender of MDI （diphenylmethane diisocyanate） prepolymer, a thermal reversible type BPU[BPA extended TPU （thermoplastic polyurethane）] was prepared. The influences of--NCO group change on BPU＇s deblocking behavior and again blocking behavior after deblocking were in real time tracked by infrared spectrum （FT-IR） method. The research results showed that the deblocking speed of--NCO group was increased with increasing temperature, and the again blocking reaction of --NCO group could be occurred in cooling process. The initial deblocking temperature is higher, and then the again blocking reaction speed is faster, and the needed time for reaching balance reaction is shorter. The melt fluidity at high temperature of BPU was increased with increasing constant temperature time or BPA content, and the increased speed of melt outflow content had the trend of little- big with increasing R[R=n（-NCO ）/n（-OH ） ] value.