Process for the manufacture of fluoroelastomers having bromine or lodine atom cure sites

Inactive Publication Date: 2007-05-03
DUPONT PERFORMANCE ELASTOMERS L L C
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

A general problem with the use of either iodine- or bromine-containing cure sites or comonomers is related to the generally high specific gravity of these compounds.
Because these materials settle to the reactor bottom, they may be incorporated unevenly into polymer chains such that a portion of the chains has an abnormally high amount of cure site while other portions have an abnormally low amount of cure site.
This will result in undesirable variability in the end use performance of products made from fluoroelastomers.
Another consequence of the high specific gravity is that a portion of the iodine- or bromine-containing compound may not even become incorporated into the polymer, resulting in reduced efficiency of the iodine- or bromine-containing compound, and the need for additional waste treatment facilities to capture any residual iodine- or bromine-containing cure site or chain transfer agent.
Yet another consequence of the high specific gravity is poor viscosity control of the resulting fluoroelastomer polymer, because...

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

[0065] A 41 liter reactor was charged with a water solution containing 17.5 grams perfluorohexylethylsulfonic acid, 12.9 grams disodium phosphate heptahydrate, and 24,969.6 grams deionized water. The reactor was brought to 80° C. and flushed with nitrogen to remove oxygen and then pressurized to 1.38 MPag with a mixture of 43 wt. % vinylidene fluoride, 3 wt. % tetrafluoroethylene, and 54 wt. % perfluoro(methyl vinyl ether). 30.0 grams of a solution of 1 wt. % ammonium persulfate and 5 wt. % disodium phosphate heptahydrate was added to initiate polymerization. As the reactor pressure dropped, a monomer feed of 55 wt. % vinylidene fluoride, 10 wt. % tetrafluoroethylene, and 35 wt. % per perfluoro(methyl vinyl ether) was added to maintain pressure. After 90 grams of this monomer mixture had been added, an emulsion of a mixture of 1,4-diiodooctafluorobutane and 1,6-diiodododecafluorohexane in a 1% (wt basis) perfluorohexylethylsulfonic acid solution in water, prepared according to Metho...

example 2

[0066] A 41 liter reactor was charged with a water solution containing 17.5 grams perfluorohexylethylsulfonic acid, 12.9 grams disodium phosphate heptahydrate, and 24,969.6 grams deionized water. The reactor was brought to 80° C. and flushed with nitrogen to remove oxygen and then pressurized to 1.38 MPag with a mixture of 43 wt. % vinylidene fluoride, 3 wt. % tetrafluoroethylene, and 54 wt. % perfluoro(methyl vinyl ether). 30.0 grams of a solution of 1 wt. % ammonium persulfate and 5 wt. % disodium phosphate heptahydrate was added to initiate polymerization. As the reactor pressure dropped, a monomer feed of 55 wt. % vinylidene fluoride, 10 wt. % tetrafluoroethylene, and 35 wt. % per perfluoro(methyl vinyl ether) was added to maintain pressure. After 90 grams of this monomer mixture had been added, an emulsion of a mixture of 1,4-diiodooctafluorobutane and 1,6-diiodododecafluorohexane in 1% (wt basis) perfluorohexylethylsulfonic acid solution in water, prepared according to Method ...

example 3

[0070] A 41 liter reactor was charged with a water solution containing 17.5 grams perfluorohexylethylsulfonic acid, 12.9 grams disodium phosphate heptahydrate, and 24,969.6 grams deionized water. The reactor was brought to 80° C. and flushed with nitrogen to remove oxygen and then pressurized to 1.38 MPag with a mixture of 43 wt. % vinylidene fluoride, 3 wt. % tetrafluoroethylene, and 54 wt % perfluoro(methyl vinyl ether). 30.0 grams of a solution of 1 wt. % ammonium persulfate and 5 wt. % disodium phosphate heptahydrate was added to initiate polymerization. As the reactor pressure dropped, a monomer feed of 55 wt. % vinylidene fluoride, 10 wt. % tetrafluoroethylene, and 35 wt. % perfluoro(methyl vinyl ether) was added to maintain pressure. After 90 grams of this mixture had been added, a 5 volume % emulsion of a mixture of 1,4-diiodooctafluorobutane and 1,6-diiodododecafluorohexane in 1 wt. % perfluorohexylethylsulfonic solution, prepared as described in Method B (above), was fed a...

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PUM

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Abstract

Fluoroelastomers having bromine, iodine or both iodine and bromine cure sites are prepared by an emulsion polymerization process wherein any iodine or bromine containing comonomers and any iodine or bromine containing chain transfer agents are introduced to the reactor as aqueous emulsions, optionally containing a surfactant.

Description

CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application claims the benefit of U.S. Provisional Application No. 60 / 731,381 filed Oct. 28, 2005.FIELD OF THE INVENTION [0002] This invention relates to a process for the manufacture of fluoroelastomers having bromine, iodine or both bromine and iodine atom cure sites wherein the comonomer or chain transfer agent containing said bromine or iodine atoms is added to the polymerization reactor in the form of an aqueous emulsion. BACKGROUND OF THE INVENTION [0003] Fluoroelastomers having excellent heat resistance, oil resistance, and chemical resistance have been widely employed for sealing materials, containers, and hoses. Examples of fluoroelastomers include copolymers comprising units of vinylidene fluoride (VF2) and units of at least one other fluorine-containing monomer such as hexafluoropropylene (HFP), tetrafluoroethylene (TFE), chlorotrifluoroethylene (CTFE), vinyl fluoride (VF) and fluoroethers such as a perfluoro(alkyl vinyl...

Claims

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Application Information

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IPC IPC(8): D06M15/277
CPCC08F214/18C08F214/22C08F214/26
Inventor LYONS, DONALD F.WIJNANDS, PAULUS ENGELBERT MARIE
Owner DUPONT PERFORMANCE ELASTOMERS L L C
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