本发明涉及多异氰酸酯聚合领域，具体涉及一种催化剂及其制备方法、异氰酸酯的聚合方法。所述催化剂为哌嗪类季铵碱类化合物，所述催化剂的制备方法步骤为：在Ar气氛保护下，将环氧丙烷滴加到哌嗪的脂肪族取代衍生物的水溶液中；在室温下搅拌，进行反应4‑9h；反应结束后取下层溶液，旋蒸得到哌嗪类季铵碱化合物，即所述催化剂。所述异氰酸酯聚合的方法为：在惰性气体的保护下，将异氰酸酯原料上述的催化剂的催化作用下进行聚合反应；当反应液中‑NCO含量基于反应液的重量达到5‑80wt％时，中止聚合反应。本发明在催化剂中引入环状哌嗪骨架，促进了小分子之间的反应，同时抑制大分子与小分子之间的反应，从而提高了底物的转化率并保证了产物的纯度。

The present invention relates to the field of polyisocyanate polymerization, in particular to a catalyst and its preparation method, as well as a polymerization method for isocyanates. The catalyst is a piperazine quaternary ammonium base compound, and the preparation method steps of the catalyst are as follows: under Ar atmosphere protection, epoxy propane is dropwise added to an aqueous solution of aliphatic substituted derivatives of piperazine; Stir at room temperature for 4-9 hours of reaction; After the reaction is completed, take the lower solution and spin evaporate to obtain piperazine quaternary ammonium base compounds, which are the catalysts. The method of polymerization of isocyanate comprises the following steps: under the protection of inert gas, polymerizing the isocyanate raw material under the catalysis of the catalyst mentioned above; When the NCO content in the reaction solution reaches 5-80wt% based on the weight of the reaction solution, the polymerization reaction is stopped. The present invention introduces a cyclic piperazine framework into the catalyst, promoting the reaction between small molecules while suppressing the reaction between large and small molecules, thereby improving the conversion rate of the substrate and ensuring the purity of the product.