硝酸法和亚砜法生产PAN基碳纤维的工艺技术对比分析

Comparison and analysis of process routes of PAN based carbon fiber prepared by nitric acid method and sulfoxide method

聚丙烯腈(PAN)基碳纤维的生产方法主要有硝酸法和亚砜法,两种工艺路线均为均相溶液聚合、湿法纺丝、热处理,生产工序及装置相同,但在聚合和纺丝工序存在工艺技术区别;对比分析两种工艺路线中聚合和纺丝工艺的技术特点及其对热处理工艺和碳纤维质量的影响。结果表明:硝酸法以硝酸作为均相溶剂,采用复合引发剂体系,亚砜法以二甲基亚砜作为均相溶剂,采用单一引发剂偶氮二异丁腈;硝酸法采用的溶剂和引发剂带入到碳纤维生产过程中的杂质较多,在纤维进行热处理时,金属离子的逸出造成了碳纤维的结构缺陷,降低了碳纤维的力学性能;亚砜法生产的碳纤维内部结构更加均一,纤维力学性能优于硝酸法,纤维拉伸强度比亚砜法的高0.5~1.0 GPa;生产PAN基碳纤维,亚砜法要比硝酸法的工艺更安全,对终端产品碳纤维的质量控制更有利,硝酸法将逐渐被淘汰,亚砜法逐渐成为主流技术。

The production technology of polyacrylonitrile(PAN) based carbon fiber mainly include nitric acid method and sulfoxide method. The two process routes both comprise homogeneous solution polymerization, wet spinning and heat treatment and have the same production processes and devices, but there are technological differences in polymerization and spinning processes. The technical characteristics of polymerization and spinning processes in the two process routes and their effects on heat treatment and carbon fiber quality were compared and analyzed. The results showed that nitric acid method used nitric acid as a homogeneous solvent and adopted a composite initiator system when sulfoxide method used dimethyl sulfoxide as a homogeneous solvent and adopted a single initiator of azodiisobutyronitrile;solvents and initiators used in nitric acid method brought more impurities into the production process of carbon fibers, and the escape of metal ions caused the structural defects and reduced the mechanical properties of carbon fibers when the fibers were heat treated;as compared with the one prepared by nitric acid method, the carbon fiber produced by sulfoxide method possesses more uniform internal structure, better mechanical properties and the tensile strength growth of 0.5-1.0 GPa;sulfoxide method was safer than nitric acid method for the production of PAN-based carbon fiber and was more beneficial to the quality control of the end products of carbon fiber;therefore nitric acid method will be gradually eliminated and sulfoxide method will gradually become the mainstream technology.