Process for production of polycarbodiimide resin powder

摘要

The present invention provides a process for producing a polycarbodiimide resin powder, which comprises reacting an organic diisocyanate in the presence of a carbodiimidization catalyst in a solvent to produce a polycarbodiimide resin and obtaining said resin in a powder form, wherein the organic diisocyanate is a compound represented by the following formula <CHEM> (wherein R1 is a lower alkyl group or a lower alkoxyl group), or <CHEM> (wherein R2 and R3 are independently a hydrogen atom, a lower alkyl group or a lower alkoxyl group, and X is an oxygen atom or a methylene group), or <CHEM> (wherein R4 and R5 are independently a hydrogen atom, a lower alkyl group or a lower alkoxyl group); the solvent is a mixed solvent of a good solvent to polycarbodiimide resin and a poor solvent to said resin, having a precipitation number of 30-80; and when the reaction has reached a certain stage, the reaction system is cooled to make the system a slurry of a polycarbodiimide, and then the polycarbodiimide is obtained in a powder form. Said process eliminates the problems of the prior art and can produce a polycarbodiimide resin powder of relatively high molecular weight simply using no terminal-blocking agent.