Synthesis of alkynyl phosphite ligands and its application in the preparation of high stability one‐component heat‐curable silicone rubber

Abstract

Hydrosilylation reaction is one of the main ways to obtain silicone rubber vulcanized products in the industry. However, it still remains a challenge for the currently used catalyst to obtain one‐component silicone rubbers with Karstedt's catalyst. In this work, we synthesize a series of phosphite ligands by transesterification, which are further used in combination with Karstedt's catalyst to prepare one‐component silicone rubber. The structure of the ligand is characterized by Fourier transform infrared spectroscopy and nuclear magnetic resonance and the vulcanization properties of silicone rubber are investigated by rotorless vulcanizer, differential scanning calorimeter (DSC) and rotational viscometer. It is found that the complex catalysts have low catalytic activity at ambient temperature when the ratio of P:Pt exceeds 1:1. The viscosity growth results show that the prepared silicone rubber has a storage time of more than 30 days at 25°C, and can be completely cured within 10 min at 150°C. The DSC results indicate that one of the prepared catalysts exhibited relatively strong catalytic activity only above 110.7°C. Moreover, the prepared complex catalyst can effectively avoid the production of colloidal platinum and prolong the storage stability of the catalyst.