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End group treatment method of fluororesin PFA for extrusion

A treatment method and fluororesin technology, applied in the field of fluororesin materials, can solve the problems of corrosion, reduce fluoropolymer end groups, long treatment period, etc., and achieve the effect of improving application field, reducing corrosion, and shortening treatment time.

Inactive Publication Date: 2020-03-27
ZHONGHAO CHENGUANG RES INST OF CHEMICALINDUSTRY CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0007] The PFA molecular chain segment synthesized by an inorganic initiator contains more unstable end groups, such as carboxyl (-COOH), double bond unsaturated group (-CF=CF2), acid fluoride group (-COF), etc., these groups Oxidation produces acidic substances and volatile substances such as hydrofluoric acid, which makes PFA products have strong acidity, resulting in molten PFA being corrosive to most metal substrates, thus affecting the application of this material
[0008] Patents US4657380, US4743658, US4946902, US5045605, and US4742122 reported that the unstable terminal groups of fluoropolymers were fluorinated into CF3 by fluorination. In these reported treatment processes, fluorine gas with strong oxidizing properties is required, which is harmful to equipment. The requirements are high, and the equipment is highly corrosive, which is not conducive to environmental friendliness and industrial production
[0009] Patent EP1170303 reported that in the process of fluoropolymer melt processing, the introduction of oxygen can effectively reduce the number of fluoropolymer end groups. This method has a long treatment cycle, which is not conducive to industrialization and mass production

Method used

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  • End group treatment method of fluororesin PFA for extrusion
  • End group treatment method of fluororesin PFA for extrusion

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0047] This embodiment provides a fluororesin for extrusion and its preparation method, the specific steps are as follows:

[0048] Adjust the PH of the fluororesin PFA emulsion polymerized by emulsion to be 9, and obtain fluororesin PFA powder for extrusion with a water content of 30% after coagulation and washing, and put it into a stainless steel pan with a thickness of 7cm; put the powder in After sintering at 290°C for 8 hours, the resin is in the form of small balls and sticky. Use twin-screws with a length-to-diameter ratio of 75:1 for end-group treatment. The process control parameters of the twin-screws are as follows. End-group treatment and After granulation, the granular resin was placed in an oven at 140°C and dried for 8 hours.

[0049] Specifically, Sections 1-3 are heating and melting zones, Sections 4-8 are terminal group treatment zones; Sections 9-15 are cooling forming zones, and the temperature of the terminal group treatment zone is 425°C.

[0050]

...

Embodiment 2

[0054] This embodiment provides a fluororesin for extrusion and its preparation method, the specific steps are as follows:

[0055] Adjust the PH of the fluororesin PFA emulsion polymerized by emulsion to be 8, and obtain fluororesin PFA powder for extrusion with a water content of 38% after coagulation and washing, and put it into a stainless steel pan, and the thickness of the powder is 6cm; After sintering at 294°C for 9.2 hours, the resin is in the form of small balls and sticky. Use twin-screws with a length-to-diameter ratio of 78:1 for end-group treatment. The temperature in the end-group treatment zone of the twin-screws is 455°C. After terminal group treatment and granulation, the granular resin was placed in an oven at 160°C and dried for 8 hours.

[0056] The fluororesin PFA for extrusion was obtained, the resin was transparent and granular, the melting temperature was 308°C, the melting index was 25g / 10min, and the density was 2.14g / cm 3 , The number of black spot...

Embodiment 3

[0058] This embodiment provides a fluororesin for extrusion and its preparation method, the specific steps are as follows:

[0059] Adjust the PH of the fluororesin PFA emulsion polymerized by emulsion to be 9, and obtain fluororesin PFA powder for extrusion with a water content of 35% after coagulation and washing, and put it into a stainless steel pan, and the thickness of the powder is 5 cm; After sintering at 285°C for 10 hours, the resin is in the form of small balls and sticky. Use twin-screws with an aspect ratio of 80:1 for end-group treatment. The temperature of the end-group treatment zone of the twin-screws is 465°C. After base treatment and granulation, the granular resin was placed in an oven at 120°C and dried for 8 hours.

[0060] The fluororesin PFA for extrusion was obtained, the resin was transparent and granular, the melting temperature was 302°C, the melting index was 22g / 10min, and the density was 2.13g / cm 3 , The number of black spots ≤ 1%, the tensile s...

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Abstract

The invention relates to the field of fluororesin materials, particularly to an end group treatment method of a fluororesin PFA for extrusion. The method comprises the following steps: carrying out drying sintering on a fluororesin PFA, carrying out double-screw stabilization treatment, and granulating, wherein the sintering temperature of the drying sintering is 280-300 DEG C, the sintering timeis 8-10 hours, the sintered fluororesin PFA is subjected to stabilizing treatment through a double-screw extruder, the temperature of the end group treatment section of the double-screw extruder is 420-465 DEG C, and the retention time of the fluororesin PFA in the double screw is 3-5 minutes. The preparation method disclosed by the invention does not need to add any auxiliary agents in a preparation process, is simple to operate, short in treatment period and beneficial to industrial production, reduces the corrosivity of fluororesin PFA products for extrusion to metal base materials, improves the application field of the material, and is stable in process, environment-friendly, short in treatment time and suitable for industrial production.

Description

technical field [0001] The invention relates to the field of fluororesin materials, in particular to a method for treating PFA end groups of fluororesin used for extrusion. Background technique [0002] Fluororesin PFA is a copolymer of tetrafluoroethylene and perfluoroalkyl vinyl ether. It is a very important new type of fluorine-containing resin. Its chemical stability, physical and mechanical properties, electrical insulation, lubricity, Aging resistance, non-combustibility and thermal stability are very good, similar to ordinary polytetrafluoroethylene (PTFE), the high-temperature mechanical strength is about 2 times higher than ordinary PTFE, has good thermoplasticity, overcomes the shortcomings of PTFE difficult to process, and can be used The general thermoplastic molding process is processed, so PFA is also called meltable polytetrafluoroethylene. [0003] Perfluoroalkyl vinyl ether in fluororesin PFA usually refers to perfluoro-n-propyl vinyl ether (PPVE) with a mo...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08J3/00C08F214/26C08F8/00
CPCC08F8/00C08J3/00C08J2327/12C08F214/262
Inventor 余金龙汪仲权姚权卫张廷健张春静苏小龙胡显权
Owner ZHONGHAO CHENGUANG RES INST OF CHEMICALINDUSTRY CO LTD