Fluoropolymers resistant to stress cracking

A stress cracking, composition technology, applied in the field of fluoropolymers, which can solve the problems of not having high temperature properties and thermal stability

Inactive Publication Date: 2004-09-08
3M INNOVATIVE PROPERTIES CO
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, FEP does not have the high temperature properties and thermal stability of PTFE

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0052] Example 1 Preparation of Fluoropolymer

[0053] 30 L of deionized water and 122 g of 30 wt % ammonium perfluorooctanoate solution were charged into a polymerization reactor with a total capacity of 40 L and an impeller stirrer. The reactor was sealed, evacuated, purged with nitrogen, and heated to 70°C.

[0054] Inject 240g of liquid CF into the reactor with a pump 2 = CFOCF 2 CF 3 (PPVE-1) and ethane at a pressure of 0.02 bar, followed by stirring while adding TFE to a total pressure of 12.0 bar. HFP was then added until the total pressure was 17.0 bar. Polymerization was initiated by pumping 2 g of ammonium persulfate (APS) dissolved in 100 mL of deionized water. When the pressure started to drop, TFE was added according to the target ratio of FEF / PPVE / HFP to maintain the total pressure at 17.0 bar. The heat generated was removed by cooling the walls of the vessel, maintaining the temperature at 70°C. After a total of 12 kg of TFE had been fed to the reactor, t...

Embodiment 2

[0058] The fluorine-containing polymer was prepared as described in Example 1, so that it contained 4.7 wt% (1.8 mol%) of PPVE, 2.7 wt% (1.9 mol%) of HFP, and the balance was TFE. After measurement, the melt flow index (MFI) of the copolymer was 22g / 10min. The material was subjected to stress crack resistance test conditions for more than 5 months and no cracks were observed.

[0059] Example 2 shows that by changing the amount of PPVE and HFP, materials with longer stress life can be obtained. According to DSC measurement, the melting point of this copolymer was 290°C, and no melting point peak above 300°C was observed.

Embodiment 3

[0068] The fluorine-containing polymer was prepared as described in Example 1, so that it contained 5.5 wt% (2.2 mol%) of PPVE, 2.1 wt% (1.5 mol%) of HFP, and the balance was TFE. It was determined that the melt flow index (MFI) of the copolymer was 3.4 g / 10 min. According to DSC measurement, the melting point of this copolymer was 280°C, and no melting point peak above 300°C was observed.

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Abstract

The invention provides a fluorothermoplastic composition comprising interpolymerized units derived from about 94 to about 97.5 mole percent (mol %) tetrafluoroethylene (TFE), about 2 to about 3 mol % perfluoro (propyl vinyl ether) (PPVE), and about 0.5 to about 3 mol % hexafluoropropylene (HFP). The invention also provides a fluorothermoplastic composition comprising interpolymerized units derived from about 94 to about 97 mol % TFE, about 0.75 to about 3 mol % PPVE, and about 1.5 to about 3.5 mol % HFP. These fluorothermoplastic compositions have a flex life that fits the equation: log(flex life cycles)>=0.71+4.0*(MFI<(-0.294)>), a method of making fluorothermoplastic compositions, a method of improving stress crack resistance, and fluorothermoplastic articles.

Description

field of invention [0001] The present invention relates to melt processable fluoropolymers having enhanced stress crack resistance after extrusion and having a smooth surface. Background of the invention [0002] Copolymers of tetrafluoroethylene (TFE) and hexafluoropropylene (HFP) are commonly referred to as fluorinated ethylene-propylene (FEP) resins. Wherein the content of HFP is usually in the range of about 10-20wt%. FEP resin can be melt processed because its melt viscosity can fully meet the requirements of conventional melt processing. However, FEP does not have high temperature properties and thermal stability like PTFE. Depending on the HFP content, the crystal melting point of these resins is about 250-270°C, and the maximum use temperature is about 200°C. Typical uses include wire insulation and the production of moldings. [0003] Copolymers of TFE and perfluoro(propyl vinyl ether) (PPVE) are commonly referred to as perfluoroalkoxy (PFA) resins. The content...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08F214/26
CPCC08F214/262
Inventor T·J·伯龙L·P·陈R·科白克F·科罗斯G·伯卡德
Owner 3M INNOVATIVE PROPERTIES CO
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