These are important building blocks for the production of essential polymers (LDPE, HDPE, PP) and like other chemical intermediates are currently produced mainly from petroleum feedstock.
这些都是用于生产至关重要的聚合物（LDPE，HDPE，PP）和其它类似的化学中间体的重要构建模块，它们目前主要是产自石油原料。