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Aqueous Polymerization of Fluorinated Monomer Using a Mixture of Fluoropolyether Acids or Salts

Inactive Publication Date: 2009-11-12
EI DU PONT DE NEMOURS & CO
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0134]Example 12 is performed in a manner similar to Comparative Example 7, with the polymerization agent mixtures 23 and 22 employed having a PFPEA type in accordance with the invention, PFPEA3, as shown in Table 4A. PFPEA and DA amounts in the polymerization agent mixtures are the same as in Comparative Example 7. Results are reported in Table 4B. Example 12 illustrates an advantage of the invention by achieving smaller RDPS and less residual perfluoropolyether acids or salts and / or byproducts in the dried PTFE fine powder resin as compared to polymer prepared by Comparative Example 7. The Residual Analysis test method is employed with dried fine powder resins prepared as described in Example 14.
by achieving smaller RDPS and less residual perfluoropolyether acids or salts and / or byproducts in the dried PTFE fine powder resin as compared to polymer prepared by Comparative Example 7. The Residual Analysis test method is employed with dried fine powder resins prepared as described in

Problems solved by technology

Fluoropolyether acids or salts with broad molecular weight ranges including high molecular weight fractions can result in residual high molecular weight fluoropolyether acids or salts and / or by-products in the resulting fluoropolymer which may be undesirable for some end uses.

Method used

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  • Aqueous Polymerization of Fluorinated Monomer Using a Mixture of Fluoropolyether Acids or Salts
  • Aqueous Polymerization of Fluorinated Monomer Using a Mixture of Fluoropolyether Acids or Salts

Examples

Experimental program
Comparison scheme
Effect test

examples 1-7

TFE / HFP / PEVE

[0125]Examples 1 through 7 are performed in a manner similar to comparative example 1, with the polymerization agent mixture employed having a PFPEA in accordance with the invention, PFPEA 3 or PFPEA 4, and / or varying amounts of PFPEA and DA used as shown in Table 2A. Results are reported in Table 2B. Using similar quantities of PFPEA in the polymerization agent, Examples 1 and 3 illustrate the invention by showing improved performance of polymerization as compared to Comparative Examples 1 and 3 as indicated by smaller RDPS and less coagulum. Using similar quantities of PFPEA in the polymerization agent, Examples 2 and 4 also illustrate the invention by showing improved performance of polymerization as compared to Comparative Examples 2 and 4 as indicated by smaller RDPS and less coagulum. Using significantly less PFPEA in the polymerization agent, Examples 5, 6, and 7 show equal or improved performance of polymerization as compared to Comparative Examples 1-4.

TABLE 2AP...

examples 8-9

TFE / HFP

[0128]Examples 8 and 9 are performed in a manner similar to Comparative Example 5, but the polymerization agent mixtures employed have a PFPEA in accordance with the invention, PFPEA3, and in significantly decreased amounts as shown in Table 3A. The DA amount is varied. Several other minor changes are also made including using a single fresh initiator solution produced with 3.74 wt % of ammonium persulfate (APS) that is pumped to the reactor at 3.4 mL / min during reaction, increasing the HFP pressure to 466 psig (3.31 MPa), and increasing the TFE pressure before the reaction starts to 650 psig (4.58 MPa). Results are reported in Table 3B. Examples 8 and 9 demonstrate the invention by achieving smaller RDPS and acceptable coagulum with significantly less PFPEA than Comparative Examples 5 and 6, respectively.

example 10

TFE / HFP

[0129]Example 10 is performed in a manner similar to Example 8, but the polymerization agent mixture 16 is added to the reactor while the reactor is paddle agitated at 93 rpm. The polymerization agent mixture 16 is shown in Table 3A. Results are reported in Table 3B. Example 10 illustrates the invention by producing significantly smaller particle size and less coagulum than Comparative Example 6 with only 12% of the PFPEA.

[0130]The process of the invention is illustrated in Examples 11, 12 and 13 in the polymerization of PTFE homopolymer and compared with Comparative Examples 7 and 8.

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Abstract

A composition comprising a mixture of fluoropolyether acids or salts having a number average value of about 800 to about 2500 g / mol. The amount of fluoropolyether acids or salt in the mixture having a molecular weight of not more than 500 g / mol is not more than 50 ppm by weight of the total amount of fluoropolyether acids or salts in the mixture. The amount of fluoropolyether acids or salts in the mixture having a molecular weight of 2500 g / mol or greater is not more than 40% by weight of the total amount of fluoropolyether acids or salts in the mixture. Preferably the fluoropolyether acids or salts comprise an anionic group selected from the group consisting of carboxylate, sulfonate, sulfonamide anion and phosphonate. Also disclosed is an aqueous dispersion polymerization process for fluoropolymer manufacture employing polymerization agent comprising the specified mixture of fluoropolyether acids or salts.

Description

FIELD OF THE INVENTION[0001]This invention relates to a composition comprising a mixture of fluoropolyether acids or salts and a process for the dispersion polymerization of fluorinated monomer in an aqueous polymerization medium employing a polymerization agent comprising the mixture of fluoropolyether acid or salt.BACKGROUND OF THE INVENTION[0002]A typical process for the aqueous dispersion polymerization of fluorinated monomer includes feeding fluorinated monomer to a heated reactor containing a fluorosurfactant and deionized water. Paraffin wax is employed in the reactor as a stabilizer for some polymerizations, e.g., polytetrafluoroethylene (PTFE) homopolymers. A free-radical initiator solution is employed and, as the polymerization proceeds, additional fluorinated monomer is added to maintain the pressure. A chain transfer agent is employed in the polymerization of some polymers, e.g., melt-processible TFE copolymers, to control melt viscosity. After several hours, the feeds a...

Claims

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Application Information

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IPC IPC(8): C08F2/16C09K3/00
CPCC08F6/16C08F216/1408C08F214/18C08G65/007C08G2650/48C08K5/095C08L71/02C08F14/18C08F114/26C08L27/12C08F2/16C08J3/16C08J2327/18C08L27/18C08L2201/54
Inventor BROTHERS, PAUL DOUGLASGANGAL, SUBHASH VISHNUCHAPMAN, GREGORY ALLENHOWELL, JON LEESMITH, ADAM PAUL
Owner EI DU PONT DE NEMOURS & CO