Polychlorotrifluoroethylene resin preparation method

Abstract

The invention provides a polychlorotrifluoroethylene resin preparation method, belonging to the technical field of the preparation of fluoropolymer material. The method comprises the following steps:firstly purifying polytrifluorochloroethylene, then adopting deionized water as medium and using initiator to performing chlorotrifluoroethylene polymerization in the presence of surfactant and obtaining polychlorotrifluoroethylene resin. The invention has the advantage that the polymerization reaction time is shortened to less than 10h, the conversion rate of chlorotrifluoroethylene reach above 90%, the obtained polychlorotrifluoroethylene resin has good heat resistance and processability and degradation and metachromatism can not appear under the processing temperature of 240-280 DEG C. Therefore, the method can meet the demand of industrialized production.

Description

technical field [0001] The invention belongs to the technical field of preparation of fluorine-containing polymer materials, and in particular relates to a preparation method of polychlorotrifluoroethylene resin. Background technique [0002] Polychlorotrifluoroethylene resin (PCTFE) is a thermoplastic with high added value and high performance. As a high-end product, it is often used in harsh environments where other materials cannot be used. When in contact with liquid oxygen, liquid nitrogen and liquefied natural gas, PCTFE has outstanding anti-brittle properties, excellent gas barrier characteristics, and is not affected by ultraviolet and gamma ray radiation. Among refrigerants, PCTFE has outstanding creep resistance characteristics, so it can be used for load bearing parts contacting refrigerant. [0003] PCTFE can be processed by common processes such as injection molding, extrusion, molding and transfer molding. PCTFE is mainly used to make parts of ultra-cold ref...

AI Technical Summary

Problems solved by technology

[0005] PCTFE is polymerized from chlorotrifluoroethylene (CTFE) as a raw material. In order to obtain PCTFE with sufficient molecular weight to meet the needs of practical applications, a redox initiator system is usually used to polymerize at 0-60 ° C. The oxidant of the initiator system It is persulfate or organic peroxide, and the reducing agent is sodium bisulfite or sodium metabisulfite. The actual polymerization reaction is often more than 30 hours, and the conversion rate of chlorotrifluoroethylene is 60-90%. Although the obtained PCTFE has a strength loss temperature exceeding 260°C (indicating a higher molecular weight), but there are unstable end groups on the molecular chain, which are easily degraded at a processing temperature of 240-280°C, resulting in performance deterioration and severe discoloration

[0006] U.S. Patents US2613202, US2689241 and US5453477 all disclose the preparation of PCTFE, add transition metal ions such as iron ions as accelerators to shorten the polymerization reaction time in the redox initiation system, but the actual polymerization time still reaches 20 hours, and the transition metal ion The introduction further aggravates the degradation of PCTFE at high temperature

[0007] U.S. patents US2751376, US2902477 and US3045000 use solvent-strong oxidant or ozone or chlorine to treat PCTFE powder, which can significantly improve the heat resistance of PCTFE at a processing temperature of 240-280 ° C. However, these treatment processes are difficult to apply industrially. and serious pollution

[0008] The long polymerization time during the preparation of PCTFE, the low conversion rate of chlorotrifluoroethylene, and the poor processability of the obtained PCTFE, such as easy degradation and discoloration at 240-280 ° C, are technical problems that are generally concerned by the industry and have always hoped to be solved. , but also the bottleneck restricting the industrial production of PCTFE