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Process for producing dispersions of highly fluorinated polymers

A highly fluorinated, polymer-based technology, applied in the field of ion-exchange polymer dispersions, can solve the problems of expensive preparation of PFSA final product dispersions, difficult control of distillation and dilution steps, and difficulty in regeneration

Inactive Publication Date: 2012-12-26
EI DU PONT DE NEMOURS & CO
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The distillation and dilution steps of the process have been difficult to control, making such PFSA end-product dispersions expensive to prepare and difficult to reproduce

Method used

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  • Process for producing dispersions of highly fluorinated polymers
  • Process for producing dispersions of highly fluorinated polymers

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1 to 9

[0097] Examples 1 to 9: Preparation of polymer powders

[0098] By feeding the above fluoropolymer dispersions A, B, C, D and E to figure 2 The spray dryer shown was used to prepare polymer particle powders. For Examples 1 to 9, the spray dryer used was a Niro Mobile Minor TM Closed cycle spray dryer from Niro Inc., Columbia, Maryland. In each example, the liquid dispersion was injected into the spray dryer through a two-fluid nozzle. One fluid is pressurized nitrogen and the other is a dispersion. Pressurized nitrogen was used to atomize the dispersion as the nitrogen and dispersion exited the two-fluid nozzle. Orient the nozzle downwards from the upper center of the spray dryer, as figure 2 shown. The dispersion is vented into hot nitrogen in a spray dryer and the liquid in the dispersion evaporates rapidly causing the particles of polymer and optionally additives to agglomerate and dry as the particles fall through the chamber.

[0099] The specific processing co...

Embodiment 10 to 18

[0105] Examples 10 to 18: Redispersions of powders

[0106] For each of Examples 10 to 18 below, 1-propanol was placed at room temperature and atmospheric pressure in a stainless steel vessel with an air-driven stirrer rotating at approximately 250 rpm. For Redispersion Examples 10, 12 and 14 to 18 below, the polymer powder from one of Examples 1 to 9 was weighed and added to 1-propanol. The examples from which the polymer powders were obtained and the weights of the powders are listed in Table 2 below. Depending on the example, the weight ratio of 1-propanol to polymer is from 1:1 to 9:1. The contents were stirred for at least one hour until the polymer powder was completely wetted and dispersed in 1-propanol. Distilled water, about the same weight as the 1-propanol, was added to the vessel and stirring was continued for several more hours until the dispersion was clear and colorless.

[0107] In Examples 11 and 13, where larger amounts of dispersion were produced, the i...

Embodiment 19

[0115] Example 19: Cast film

[0116] Solution cast perfluorosulfonic acid membranes were prepared from the redispersion of Example 13 according to the following procedure. The dispersion of Example 13 was drawn from the slot die to a moving on the film. The slot opening is 5 mil thick and 14 inches (35.6 cm) wide. Pump speed and line speed were adjusted to achieve a film thickness of approximately 1 mil. The film carries the film through a three zone gas flame dryer which dries the film from top to bottom. Each dryer zone was 10 inches long and the temperatures in each zone were as follows:

[0117] Zone 1: 45°C

[0118] Zone 2: 73°C

[0119] Zone 3: 96°C

[0120] Then by using The PFSA film on thin film heat treats the dried film by moving it through a three-zone gas flame dryer heating the film from top to bottom to coalesce the polymer. The dwell time of the film in each zone was 45 seconds for a total heating time of 135 seconds (+ / - 2 seconds). Each dryer ...

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Abstract

The present invention provides a method for preparing a dispersion of a highly fluorinated ion exchange polymer, wherein the dispersion of the highly fluorinated ion exchange polymer is atomized and released in a first liquid comprising at least 10% by weight of an organic liquid into a hot gas to produce flowable particles of a highly fluorinated ion exchange polymer with a dry surface / exterior and an interior residual moisture content of at least 4% by weight. The particles are dispersed in a second liquid to prepare a second dispersion of a highly fluorinated ion exchange polymer from which proton exchange membranes and electrodes for fuel cells can be prepared.

Description

field of invention [0001] The present invention relates to methods for preparing dispersions of highly fluorinated ion exchange polymers, and methods for preparing materials such as membranes or electrodes from such dispersions. Background of the invention [0002] Perfluorinated ion exchange polymers are used in the manufacture of ion exchange membranes and other structures such as electrodes for fuel cell membrane electrode assemblies (MEAs). One well known perfluorinated ion exchange polymer is perfluorosulfonic acid ("PFSA") polymer, which is generally a copolymer of fluorinated vinyl units and sulfonyl-containing comonomer units. One such polymer, disclosed in U.S. Patent 3,282,875, can be synthesized by combining tetrafluoroethylene (TFE) with perfluorovinyl ether perfluoro(3,6-dioxa-4-methyl-7-octenesulfonyl fluoride )(PDMOF)[CF 2 = CF-O-CF 2 CF(CF 3 )-O-CF 2 CF 2 SO 2 F] by copolymerization, followed by hydrolysis and acid exchange to prepare. Another exempla...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C08J3/12C08J5/22H01M8/10
CPCH01M8/1081H01M4/8605H01M8/1039H01M4/8668C08J3/122C08J3/11H01M4/8828H01M4/90H01M8/1048Y02E60/523H01M2300/0082H01M8/1051C08J2327/12C08J5/225C08J3/05Y02P70/50Y02E60/50
Inventor V·M·菲利克斯K·D·巴顿
Owner EI DU PONT DE NEMOURS & CO
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