Aqueous dispersion of polytetrafluorethylene and process for its production

A polytetrafluoroethylene, water-based dispersion technology, applied in the direction of coating, etc., to achieve the effect of excellent friction stability

Active Publication Date: 2006-12-13
ASAHI GLASS CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, when using, for example, sulfur-containing anionic surfactant sodium lauryl sulfate, the coating tends to be yellowish-brown during baking, and the sulfate remains in the coating as an ionic impurity after baking. middle
Therefore, this coating is not suitable for application in electronic materials such as printed circuit boards

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0083]Carry out emulsion polymerization in the presence of pre-added PFCA perfluorooctanoic acid ammonium of 0.25 mass % based on the mass of PTFE to obtain a water-based PFTE polymer emulsion with a PTFE concentration of 29 mass % and an average particle diameter of 0.25 microns. The molecular weight is about 3,000,000.

[0084] The nonionic surfactant (a) of 5% by mass based on the mass of PTFE was dissolved in an aqueous PTFE polymer emulsion, and 2% by mass of strong polymer manufactured by Mitsubishi Chemical Corporation was used based on the mass of PTFE. The basic anion exchange resin DIAION (registered trademark) HPA-25 was stirred for 24 hours to reduce the PFCA concentration. Then, the anion exchange resin was removed by filtration through a 200-mesh nylon filter. Then, be 0.3 mass % ammonium laurate aqueous solution (obtained as an aqueous solution by adding 200 grams of lauric acid and 120 grams of 28 mass % ammonia to 1680 grams of water as an aqueous solution) b...

Embodiment 2

[0089] Carry out according to the step in embodiment 1, difference is (b) is used as non-ionic surfactant, (e) is used as carboxylate, to obtain aqueous PTFE dispersion.

Embodiment 3

[0091] Follow the steps in Example 1, except that (c) is used as a nonionic surfactant, and (f) is used as a carboxylate.

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Abstract

To obtain a high concentration aqueous PTFE dispersion containing PTFE at a concentration of from 60 to 75 mass% by dissolving from 0.001 to 0.1 mass%, based on the mass of PTFE, of a specific carboxylic acid salt such as ammonium laurate in a low concentration aqueous dispersion of polytetrafluoroethylene (PTFE) comprising from 1 to 40 mass% of PTFE fine particles, from 0.0001 to 0.02 mass%, based on the mass of PTFE, of a specific fluorine-containing carboxylic acid type emulsifier (for example, ammonium perfluorooctanoate), and from 1 to 20 mass%, based on the mass of PTFE, of a specific nonionic surfactant, and then concentrating the low concentration aqueous dispersion of PTFE. The present invention provides a process for producing a high concentration aqueous PTFE dispersion containing PTFE at a high concentration by using, as a starting material, a low concentration aqueous dispersion of PTFE containing a fluorine-containing carboxylic acid type emulsifier (PFCA) at a low concentration, and an aqueous PTFE dispersion obtained from the high concentration aqueous PTFE dispersion.

Description

technical field [0001] The present invention relates to an aqueous dispersion of polytetrafluoroethylene (hereinafter referred to as PTFE) and its production method. Background technique [0002] Emulsion-polymerized polymers are produced by polymerization of tetrafluoroethylene (hereinafter referred to as TFE) monomers in the presence of pure water, polymerization initiators, fluorine-containing carboxylate emulsifiers (hereinafter referred to as PFCA) and paraffin stabilizers. PTFE, which is available as an aqueous PTFE polymer emulsion containing PTFE fine particles (Handbook of Fluorine Resins, page 28, edited by Takaomi Satokawa, published by Nikkankogyo Shimbun). [0003] The polymerized aqueous PTFE polymer emulsion is used as a low concentration aqueous PTFE dispersion after mixing with a nonionic surfactant, or as a high concentration aqueous PTFE dispersion after concentration. Alternatively, the polymer emulsion is used as an aqueous PTFE dispersion after mixing ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08L27/18C08J3/03
CPCC08F6/16C08F6/20C08J3/05C08J2327/18C08K5/09C08K5/19C08L27/18C08L71/02C09D127/18C08L2666/14
Inventor 星川潤樋口信弥松岡康彦
Owner ASAHI GLASS CO LTD
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