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Process for preparing fluoropolymer dispersions

A dispersion, polymer technology, used in coatings, textiles and paper, fiber processing, etc.

Inactive Publication Date: 2006-07-19
SOLVAY SOLEXIS
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0015] The disadvantage of these dispersions is that they cannot be coagulated by common procedures used with fluoropolymer dispersions, especially PTFE

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0110] emulsion polymerization

[0111] 11 grams of an aqueous solution of ammonium perfluorooctanoate at a concentration of 100 g / liter and 31 liters of suitably degassed demineralized water were introduced into a 50-liter autoclave equipped with a mechanical stirrer and previously placed under vacuum. 140 grams of paraffin wax with a softening point of 52° C. to 54° C. was also preliminarily introduced into the reactor. The autoclave was kept mechanically stirred and pressurized with TFE to 20 bar at a temperature of 68°C. At this time, 500ml (NH 4 ) 2 S 2 o 8 A solution of (APS) and disuccinic acid peroxide (DSAP), wherein 400 mg of APS and 2,000 mg of DSAP, was injected into the autoclave.

[0112] When the pressure in the reactor dropped by 0.5 bar, the injection of TFE through the compressor was started to maintain a constant pressure of 20 bar in the reactor. At the same time, the internal temperature of the reactor was raised to 78°C at a rate of 0.5°C / min. Duri...

Embodiment 2

[0114] Embodiment 2 (comparative example)

[0115] To 500 g of the dispersion obtained according to Example 1 was added 5% by weight, based on the weight of the sample, of the ion exchange resin Amberjet  4400 OH, the pH of this dispersion has been adjusted to around 9 with aqueous ammonia solution. Stir the mixture moderately with a two-blade mechanical stirrer. After having been treated for one hour, the dispersion appeared to coagulate.

Embodiment 3

[0117] 500 g of the dispersion obtained according to Example 1, the pH of which had been adjusted to around 9 with aqueous ammonia solution, and 5% Cosmacol  AES 27-3-24 in water, prepared by mixing in a beaker containing 4% Cosmacol  Dispersion samples of AES 27-3-24 (based on PTFE weight). The PTFE content of the sample thus obtained was equal to 24.2% by weight. To the sample was added 5% by weight ion exchange resin Amberjet  4400 OH, based on sample weight. The mixture was stirred moderately with a two-blade mechanical stirrer for 4 hours. Finally, the dispersion showing no fluoropolymer aggregates was separated from the resin by filtration through a 150 μm sieve. The PTFE content of the resulting dispersion was equal to 24.2% by weight. PFOA content is less than 5ppm based on PTFE weight.

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PUM

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Abstract

A process to substantially remove fluorinated anionic surfactants from fluoropolymer dispersions comprising the following steps: a) addition to the fluoropolymer dispersion of one or more non fluorinated surfactants; b) contact of the dispersion with an anionic exchanger; c) separation of the dispersion from the anionic exchanger and recovery of the dispersion substantially fluorinated anionic surfactant free.

Description

technical field [0001] The present invention relates to a process for the preparation of aqueous dispersions of fluoropolymers which are substantially free of fluorinated surfactants, in particular free of fluorinated ionic surfactants. [0002] More particularly the present invention relates to a process for the preparation of aqueous fluoropolymer dispersions substantially free of perfluorooctanoate in acid or salt form. Background technique [0003] By an aqueous fluoropolymer dispersion substantially free of fluorinated anionic surfactant is meant that the fluorinated surfactant content is less than 100 ppm, especially less than 50 ppm, more especially less than 5 ppm, based on the weight of the fluoropolymer. [0004] Two different polymerization processes for the production of fluorinated polymers are known in the prior art: suspension polymerization and emulsion polymerization. Polymer particles with millimeter dimensions are obtained in the suspension polymerization...

Claims

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Application Information

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IPC IPC(8): C08J3/00C08J11/02C08F8/26C08F2/26C08L101/04C09D201/04D06M15/227C08J5/18C09D7/80
CPCC08F6/16C08J3/03C08J2327/12C08L27/12
Inventor M·马尔瓦西V·卡佩利欧奇科
Owner SOLVAY SOLEXIS
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