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Novel polytetrafluoroethylene aqueous dispersion

A technology of polytetrafluoroethylene and dispersion, which is applied in the direction of textile, coating, fiber treatment, etc., can solve the problems of untaught water-soluble salt, etc., and achieve the effect of increasing yield and output

Inactive Publication Date: 2012-07-11
EI DU PONT DE NEMOURS & CO
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The aforementioned literature does not teach that water soluble salts can increase the CCT of aqueous dispersions

Method used

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  • Novel polytetrafluoroethylene aqueous dispersion
  • Novel polytetrafluoroethylene aqueous dispersion

Examples

Experimental program
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Effect test

preparation example Construction

[0063] Preparation method of polytetrafluoroethylene dispersion

[0064] A typical aqueous dispersion polymerization process for the preferred PTFE polymer is to pass TFE gas into a reaction kettle containing heated fluorinated surfactant, paraffin wax and deionized water. A chain transfer agent may also be added if desired to reduce the molecular weight of the PTFE. The free radical initiator solution was added and additional TFE was added to maintain pressure as the polymerization proceeded. The heat evolved by the reaction was removed by circulating cooling water in the reactor jacket. After several hours, the feeds were stopped, the autoclave was evacuated and purged with nitrogen, and the native dispersion in the autoclave was transferred to a cooling vessel. The paraffin was removed and the aqueous dispersion was isolated and stabilized with nonionic surfactants.

[0065] The aqueous fluoropolymer dispersion of the present invention may be referred to as a stabilize...

Embodiment

[0135] The abbreviation "E" means "Example", "C" means "Comparative Example", and the number following it indicates in which example the aqueous dispersion was prepared. All examples and comparative examples were prepared and tested in the same way. Percentages are by weight unless otherwise indicated.

[0136] Material

[0137] (a1) PTFE: A primary dispersion comprising about 41 to about 43% by weight of core / shell PTFE having an average particle size of 270 nm was mixed with component (b) and concentrated according to the procedure described below to obtain The final aqueous dispersion has a solids content of from about 50 to about 60% by weight.

[0138] (a2) PTFE: The primary dispersion comprising about 41 to about 43% by weight of PTFE has an average particle size of 220 nm, the dispersion is mixed with component (b) and concentrated according to the following steps to obtain a final particle size of about 50 to about 60% by weight solids content aqueous dispersion. ...

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Abstract

The invention discloses a polytetrafluoroethylene aqueous dispersion, comprising the following components in percentage by weight: 45-70% of non-melt processible polytetrafluoroethylene (PTFE) particles, 1-15 % of non ionic surfactant on the basis of the weight of the polytetrafluoroethylene particles, 1-10 % of water soluble alkaline-earth metal salt or 0.1-10% of colloidal silicon dioxide. The invention also discloses a coating composition containing the PTFE aqueous dispersion and a coating application with improved critical fracture thickness.

Description

technical field [0001] This invention relates to aqueous non-melt processible fluoropolymer dispersions and coatings formed therefrom. Background technique [0002] Fluoropolymers are used on a variety of substrates to impart anti-stick properties, chemical resistance, heat resistance, corrosion protection, cleanability, low flammability and weather resistance. Coatings of polytetrafluoroethylene (PTFE) homopolymer and modified PTFE offer the highest thermal stability among fluoropolymers, but unlike tetrafluoroethylene (TFE) copolymers, they cannot be formed by melt processing Films and Coatings. Accordingly, other methods of applying coatings of PTFE homopolymers and modified PTFEs have been developed. One such method is dispersion coating, which is applied in the form of a dispersion. [0003] Dispersion coating processes typically use fluoropolymer dispersions in a more concentrated form than the as-polymerized native dispersions. These concentrated dispersions typic...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08L27/18C08L71/02C08K3/36C08K5/06C08K3/28C09D127/18C09D7/12D06M15/256
CPCC08K5/06C09D127/18D06M15/256D06N3/047C08K3/36C08K3/28C08F14/26Y10T442/20C08K3/10C08F2/30
Inventor 廖蓉毛学圃R·G·赫克
Owner EI DU PONT DE NEMOURS & CO
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