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CN-122011357-A - Method and device for decomposing peroxy groups in perfluoropolyether

CN122011357ACN 122011357 ACN122011357 ACN 122011357ACN-122011357-A

Abstract

The invention relates to the technical field of perfluoropolyethers, in particular to a method and a device for decomposing peroxy groups in perfluoropolyethers. The method comprises the steps of 1) mixing perfluoro polyether containing peroxy groups, water and supercritical CO 2 to obtain a mixed material, 2) irradiating the mixed material with ultraviolet at the temperature of 20-100 ℃ to obtain a reaction material, 3) carrying out reduced pressure separation on the reaction material to obtain a carbon dioxide and liquid mixture, and carrying out reduced pressure evaporation on the liquid mixture to obtain hydrofluoric acid and perfluoro polyether, wherein the peroxy value of the perfluoro polyether containing peroxy groups in the step 1) is more than or equal to 0.5 mmol/g. The invention can safely and efficiently decompose the peroxy groups in the perfluoropolyether to obtain the perfluoropolyether product which has low peroxy value and is suitable for subsequent modification.

Inventors

  • ZHANG WEN
  • ZHANG MING
  • LIU BO
  • YANG XUCANG
  • ZHONG ZHIGANG

Assignees

  • 中昊晨光化工研究院有限公司
  • 中化蓝天集团有限公司

Dates

Publication Date
20260512
Application Date
20251216

Claims (10)

  1. 1. A method for decomposing peroxy groups in a perfluoropolyether comprising: 1) Mixing the perfluoro polyether containing peroxy groups, water and supercritical CO 2 to obtain a mixed material; 2) Irradiating the mixed material with ultraviolet at the temperature of 20-100 ℃ to obtain a reaction material; 3) The reaction materials are subjected to reduced pressure separation to obtain a mixture of carbon dioxide and liquid, the liquid mixture is subjected to reduced pressure evaporation to obtain hydrofluoric acid and perfluoropolyether, and in the step 1), the peroxy value of the perfluoropolyether containing peroxy groups is more than or equal to 0.5 mmol/g.
  2. 2. The method according to claim 1, wherein in step 1) the water is added in an amount of 2-20%, preferably 3-8% by weight of the perfluoropolyether containing peroxy groups.
  3. 3. The method according to claim 1 or 2, wherein in step 1) the weight ratio of supercritical CO 2 to peroxy group containing perfluoropolyether is 2-20:1, preferably 4-8:1.
  4. 4. The method according to claim 3, wherein in step 1), the peroxy value of the peroxy-group-containing perfluoropolyether is 0.5 to 5 mmol/g.
  5. 5. The method according to any one of claims 1 to 4, wherein in step 2), the temperature of the ultraviolet irradiation is 20 to 60 ℃, and/or the time of the ultraviolet irradiation is 4 to 24 hours.
  6. 6. The method of claim 5, wherein in step 2) the ultraviolet light source of ultraviolet light is selected from one or more of a high pressure mercury lamp, a low pressure mercury lamp, a metal halide lamp, a deuterium lamp, and an ultraviolet LED lamp.
  7. 7. The method according to any one of claims 1 to 6, wherein in step 3), the pressure of the reduced pressure separation is 0.5 to 7.3 MPa and the temperature is-50 to 80 ℃.
  8. 8. The method according to any one of claims 1 to 7, wherein in step 3), the reduced pressure evaporation is performed at a pressure of 0.1 to 10 MPa and a temperature of 20 to 100 ℃.
  9. 9. The method according to any one of claims 1 to 8, wherein in step 3), the gaseous CO 2 is condensed, the condensed liquid CO 2 is recycled, and/or the hydrofluoric acid is separated and recovered.
  10. 10. The reaction system of the process according to any one of claims 1 to 9, characterized by comprising a CO 2 storage tank, a CO 2 intermediate tank, a high-pressure pump, a heater, a peroxide decomposing tank, a first pressure reducing valve, a crude product separator, a second pressure reducing valve and an HF evaporator, which are connected in this order, the peroxide decomposing tank being provided with an ultraviolet light source, preferably the crude product separator being connected to an inlet of a cooler, an outlet of which is connected to the CO 2 intermediate tank.

Description

Method and device for decomposing peroxy groups in perfluoropolyether Technical Field The invention relates to the technical field of perfluoropolyethers, in particular to a method and a device for decomposing peroxy groups in perfluoropolyethers. Background Perfluoropolyethers generally refer to a class of polymers in which the main chain of the polymer contains repeating ether linkages and the hydrogen atoms in the structure are all replaced by fluorine atoms. The novel high-molecular-weight polytetrafluoroethylene has the characteristics of good thermal stability, lower intermolecular acting force, high hydrophobicity, low vapor pressure, chemical inertness, incombustibility and the like due to the unique chemical structure, is commonly called liquid polytetrafluoroethylene, and has wide application in various fields of national defense and military industry. The perfluoropolyether can be divided into K type, D type, Y type, Z type and the like according to the structure, and has two synthetic methods of anion telomerization and photo-oxidation polymerization. Wherein the photo-oxidative polymerization is prepared by copolymerizing small molecule perfluoroolefin with oxygen in an inert solvent, which produces a perfluoropolyether peroxide initial product distributed by random peroxy groups. It is known that peroxy groups are unstable and that removal of the peroxy groups contained in the initial product is necessary in order to ensure subsequent structural stability and safety in use. In the prior art, the peroxide decomposition method described in US3715378 is carried out at 100-250 ℃, but the primary product of the perfluoropolyether peroxide is directly heated, so that the danger is high, and the explosion risk exists. US3665041 and US4664766 disclose a process for the preparation of perfluoropolyether oils by reacting polyethers containing reactive end groups (optionally containing peroxy groups) with fluorine at a temperature of about 0.2 to 10 atmospheres and about 100 ℃ to 350 ℃, the peroxy groups also decomposing during the fluorination capping process, CN103724559B discloses a process for the synthesis of perfluoropolyethers from perfluoropolyether peroxides by placing the photooxidative perfluoropolyether peroxides in inert fluorine-containing solvents, under uv irradiation conditions, introducing a perfluoroolefin, reacting the perfluoroolefin with peroxide to form stable perfluoropolyether compounds, and continuing to react with the perfluoroolefin under uv irradiation conditions, the decomposition products obtained by the process described above being terminally fluorinated capped perfluoropolyether oils, without reactivity, and application limitations. CN106317398B provides a method for decomposing peroxide in perfluoropolyether, which comprises adding one or more of metal catalyst, metal oxide catalyst and metal fluoride catalyst into perfluoropolyether product prepared by photooxidation method, and decomposing peroxide in perfluoropolyether product at 80-150 ℃. The peroxide value of the perfluoropolyether material adopted before decomposition is 1-10 multiplied by 10 -2 mmol/g, the peroxide value in the range belongs to a safe range, the problem that the substrate perfluoropolyether peroxide is decomposed in a high peroxide value (such as 0.5-5 mmol/g) range cannot be solved, the peroxide value of the adopted decomposition raw material is higher, the danger of reaction is higher, and the requirement on process control is higher. There is an urgent need to provide a novel method for decomposing peroxy groups in perfluoropolyethers. Disclosure of Invention In order to solve the technical problems, the invention provides a method and a device for decomposing peroxy groups in perfluoropolyether. The invention can safely and efficiently decompose the peroxy groups in the perfluoropolyether to obtain the perfluoropolyether product which has low peroxy value and is suitable for subsequent modification. According to the invention, supercritical CO 2 is used as a solvent, and after the perfluoropolyether containing the peroxy groups is dissolved, ultraviolet irradiation is performed at a lower temperature, so that the peroxy groups in the perfluoropolyether can be safely and effectively decomposed. Supercritical CO 2 is an environmentally friendly excellent solvent that does not itself create any chemical contamination, as compared to the solution with fluorine containing solvents. HF and COF 2 are generated during the decomposition of the peroxy group, and the latter rapidly generates HF and CO 2 when meeting water. The invention realizes the separation of three substances by utilizing the vaporization temperature difference of CO 2, HF and perfluoropolyether through process design, recovers the byproduct HF and realizes the recycling of CO 2. Meanwhile, the activity of the end group can be maintained in the illumination process, and the subsequent structural modification is not influenced. In a