Perfluoropolyether end group fluorination method

Abstract

The invention provides a perfluoropolyether end group fluorination method which comprises the following steps: (1) irradiating mixed gas of fluorine gas and inert gas by using ultraviolet light, and activating; and (2) introducing the activated mixed gas into a reaction kettle filled with perfluoropolyether acyl fluoride, and reacting to obtain the end group fluorinated perfluoropolyether. According to the method disclosed by the invention, the fluorination reaction can be carried out at normal temperature, the obtained perfluoropolyether is easy to post-treat, the low-molecular-weight perfluoropolyether acyl fluoride product is less in loss, and the structure, the average molecular weight, the viscosity and the like of the fluorinated product are not changed.

Description

technical field [0001] The invention relates to the field of perfluoropolyether, in particular to a method for fluorinating the terminal group of perfluoropolyether. Background technique [0002] Perfluoropolyether is a fluoropolymer with high chemical inertness, oxidation resistance and corrosion resistance. Compared with perfluorocarbon chains, it has the advantages of flexibility, low glass transition temperature, and extremely wide co-liquid temperature range (freezing point to boiling point), and is widely used in the lubrication of aerospace, electronics, machinery and nuclear industries. agent. [0003] At present, there are two main methods for preparing perfluoropolyether, one is anionic ring-opening polymerization using hexafluoropropylene oxide as raw material, and the other is photooxidative polymerization using tetrafluoroethylene or hexafluoropropylene as raw material. The perfluoropolyether obtained by these two methods has a terminal acyl fluoride structure...

AI Technical Summary

Problems solved by technology

[0004] There are currently two main methods for fluorinating perfluoropolyether end groups, one is to use AlF 3 , SbF 5 Waiting for fluoride salt as a fluorinating agent, such as the method described in patent WO2009054569A1, the main disadvantage of this method is that fluoride salt is expensive, and the metal elements introduced into the product are difficult to separate, and will seriously affect product quality

Another method is the direct fluorination method using fluorine gas, such as the methods described in Chinese patents CN103111253A, CN106397761A, CN110092901A, etc., but the main disadvantage of this method is that the direct fluorination of fluorine gas generally requires high temperature and low molecular weight perfluorinated The boiling point of polyether is low, it is easy to cause loss during fluorination, and high temperature is easy to cause great loss to equipment, which is not conducive to industrial production

U.S. Patent No. 4,664,766A mentioned that the use of ultraviolet light to irradiate perfluoropolyether and fluorinated gas can neutralize perfluoropolyether and reduce the fluorination temperature, but the main disadvantage of this method is that ultraviolet light directly acts on perfluoropolyether Acyl fluoride raw materials can trigger the self-polymerization of perfluoropolyether itself, resulting in changes in molecular structure, average molecular weight, viscosity, etc.

[0005] To sum up, in the prior art, there are problems such as product post-processing troubles, high temperature easily causing product loss, and easily causing product molecular structure changes.

Images