High purity perfluoroelastomer composites and a processes to produce the same

a perfluoroelastomer composite and high purity technology, applied in the direction of coatings, emulsion paints, etc., to achieve the effect of minimizing corrosion, minimizing contamination, and eliminating metallic contamination

Inactive Publication Date: 2006-11-30
WL GORE & ASSOC INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0009] In one embodiment, methods of the present invention minimize contamination in part by minimizing corrosion that results from conventional polymerization processes performed in the presence of perfluorocarboxylic acid salt by using a non-metallic buffer and / or corrosion resistant vessel and / or lines. Corrosion resistant materials useful in the present invention include high Ni alloys, for example, Inconel® or Hastelloy® alloys. Processes of present invention may also solve the problem of contamination encountered by coagulation of the emulsion or dispersion using metallic salts. For example, by using nitric acid (HNO3) or ammonium salts like (NH4)2CO3 and NH4NO3 as coagulants, metallic contamination can be minimized or eliminated. Known methods for curing elastomeric resin may result in contamination by using compounding steps that add metallic and / or other contaminants, or by corrosion of the compounding equipment, or exposure to environmental contamination. It has been unexpectedly discovered that perfluoroelastomeric uncrosslinked gum, having a low concentration of perfluoro carboxylic acids or salt containing perfluoro cyano vinyl ether crosslink sites, such as 8-CNVE, can be cured in the mold at about 250° C., or greater than 250° C., without a compounding step and without the addition of any other chemicals.

Problems solved by technology

Known methods for curing elastomeric resin may result in contamination by using compounding steps that add metallic and / or other contaminants, or by corrosion of the compounding equipment, or exposure to environmental contamination.

Method used

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  • High purity perfluoroelastomer composites and a processes to produce the same
  • High purity perfluoroelastomer composites and a processes to produce the same
  • High purity perfluoroelastomer composites and a processes to produce the same

Examples

Experimental program
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Effect test

example 1

[0043] An aqueous emulsion containing 10 g 8-CNVE [CF2═CF—O—(CF2)3—O—CF(CF3)—CN], 135 g deionized (DI) water and 5 g 20 wt % ammonium perfluorooctanoate (APFO) aqueous solution was prepared by using an Omini Mixer Homogenizer (Omini International Co.) for 5 minutes. This solution is designated as “stock solution A”.

[0044] Approximately 1500 g DI water, 300 g 20 wt % APFO aqueous solution and 16 g 8-CNVE were charged into an oxygen-free 4-liter reactor. Then, 190 g TFE and 300 g PMVE were added into the reactor. The reactor was then heated to 70° C. under 2285 KPa and the polymerization reaction was initiated by feeding 202 g ammonium persulfate (APS) aqueous solution (2 g APS dissolved in 200 g DI water) within 2 minutes. As the reaction pressure decreased to 1800 KPa, 105 g stock solution A with 120 g DI water and 20 g TFE were charged into the reactor within 3 minutes. Then, 150.5 g APS solution (0.5 g APS dissolved in 150 DI water) was fed into the reactor within 1 minute. As th...

example 2

[0049] An aqueous solution containing 10 g 8-CNVE [CF2═CF—O—(CF2)3—O—CF(CF3)—CN], 136 g DI water and 4 g of 20 wt % APFO aqueous solution was prepared by using an Omini Mixer Homogenizer for 5 minutes. This solution is designated as “stock solution B”.

[0050] Approximately 1500 g DI water, 300 g 20 wt % APFO aqueous solution and 16 g 8-CNVE were charged into an oxygen-free 4-liter reactor. Then, 190 g TFE and 320 g PMVE were added into the reactor. The reactor was then heated to 70° C. under 2347 KPa and the polymerization reaction was initiated by feeding 200.5 g APS aqueous solution (0.5 g APS dissolved in 200 g DI water) within 1 minute. As the reaction pressure decreased to 1900 KPa, 105 g stock solution B with 120 g DI water and 20 g TFE were charged into the reactor within 2 minutes. As the reaction pressure decreased to 1700 KPa, 45 g stock solution B with 150 g DI water and 20 g TFE were charged into the reactor within 2 minutes. The polymerization reaction was stopped after...

example 3

[0056] An aqueous solution containing 10 g 8-CNVE [CF2═CF—O—(CF2)3—O—CF(CF3)—CN], 480 g DI water and 10 g 20 wt % APFO aqueous solution was prepared by using an Omini Mixer Homogenizer for 5 minutes. This solution is designated as “stock solution C”.

[0057] Approximately 1500 g DI water, 300 g 20 wt % APFO aqueous solution and 16 g 8-CNVE were charged into an oxygen-free 4-liter reactor. Then, 260 g TFE and 300 g PMVE were added into the reactor. The reactor was then heated to 70° C. under 2584 KPa and the polymerization reaction was initiated by feeding 200.2 g APS aqueous solution (0.2 g APS dissolved in 200 g DI water) within 1 minute. Then, stock solution C was fed into the reactor as follows:

Time after reaction initiationStock solution C added(in minutes)(in grams)26016602860406051506160726083809810

[0058] As the reaction pressure decreased to 2120 KPa, 20 g TFE was charged into the reactor within 1 minute. Another 20 g TFE was added into the reactor within 1 minute as the rea...

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Abstract

High purity perfluoroelastomer composites and processes for producing the same are provided. High purity composites may be formed from compositions comprising a crosslinkable fluoroelastomer terpolymer of TFE, PAVE, and CNVE, and functionalized PTFE, which may be crosslinked to form crosslinked composites having low metal content and low compression set. Emulsion mixtures for forming the high purity composites are also provided.

Description

BACKGROUND OF THE INVENTION [0001] Perfluoroelastomers have achieved outstanding commercial success and are used in a wide variety of applications in which severe environments are encountered, in particular those end uses where exposure to high temperatures and aggressive chemicals occurs. For example, these polymers are often used in seals for aircraft engines, in semiconductor manufacturing equipment, in oil-well drilling devices, and in sealing elements for industrial equipment used at high temperatures. [0002] The outstanding properties of perfluoroelastomers are largely attributable to the stability and inertness of the copolymerized perfluorinated monomer units that make up the major portion of the polymer backbones in these compositions. Such monomers include tetrafluoroethylene (TFE) and perfluoro(alkyl vinyl) ethers (PAVE). In order to develop elastomeric properties fully, perfluoroelastomers are typically crosslinked, i.e. vulcanized. To this end, a small percentage of cur...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): C09D5/02
CPCC08L27/12C08L27/18C08L33/22C08L29/10C08K3/36C08L2205/02C08L2666/04
Inventor XU, PINGHEGENBARTH, JACK
Owner WL GORE & ASSOC INC
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