The Dow Chemical Company

Robert E Aikman, Jr

William P Carl

Emmett L Tasset

Charles W Martin

John N Zabasajja

John W Gross, Sr

An improved process for forming a thin, durable coating of a perfluorosulfonated, salt- or acid-form ionomer on a selected substrate, which comprises contacting the substrate with an aqueous, surface active dispersion of the thermoplastic, sulfonyl fluoride precursor of the perfluorosulfonated, salt- or acid-form ionomer, contacting the dispersion-wetted substrate with a salt solution or a strongly ionizing acid solution of a sufficient ionic strength to cause a thin, adherent coating of the precursor particles in said dispersion to be formed on the substrate, then removing excess dispersion and excess salt or acid solution, annealing the coated substrate at an elevated temperature and thereafter converting the precursor to the desired acid or salt form ionomer.

Processes for forming thin, durable coatings of perfluorocarbon ionomers

A bonded, non-asbestos chlor-alkali diaphragm comprising one or more water-wettable materials and one or more chemically-resistant materials, which is characterized by having a Macmullin number and average diaphragm thickness such that the product of these is between about 5 and about 30 millimeters when the average diaphragm thickness is measured in millimeters, and by a median pore size between about 0.1 microns and about 1 micron, wherein one or more of the chemically-resistant materials is or are coated with a durable, adherent coating of an ion-containing polymer which is bonded into the diaphragm on such materials.

Non-asbestos diaphragm separator

The invention is a process for producing a modified polytetrafluoroethylene which comprises polymerizing tetrafluoroethylene in an aqueous medium containing a dispersing agent with a polymerization initiator source and then, copolymerizing tetrafluoroethylene one or more fluorinated modifiers having an acid functional group or a functional group which is convertible to the acid group as a copolymerizable modifier in the presence of the resulting polytetrafluoroethylene to a polymerization point past the Kraft point to produce highly porous, fibrous, stratified fluoropolymers having cores made of homopolymer of poly-tetrafluoroethylene coated with sheath layers which are made of a copolymer of polytetrafluoroethylene and one or more modifiers. The invention also includes a highly porous, fibrous, stratified fluoropolymer having a plurality of interconnected, fibrous-like projections wherein the stratified fluoropolymer has a core layer of polytetrafluoroethylene substantially completely covered by a copolymer of polytetrafluoroethylene and a fluorocarbon modifier.

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Lake Jackson, TX, United States of America

Robert E Aikman, Jr