# US 5,700,572 A · PTFE fibre material and process for making it

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- Number: US 5,700,572 A
- Document ID: US5700572A
- Status: Granted
- Kind: A
- Application number: 08/325,285
- Filed: 1995-06-02
- Granted: 1997-12-23
- Earliest claimed: 1991-09-12
- Assignees: Heraeus Elektrochemie GmbH; Magdeburger Energie - und Umwelttechnik GmbH
- Inventors: Bruno Klatt; Manfred Horx; Hartmut Koelling; Karlheinz Berndt; Gerhard Krueger; Hans-Joachim Kuenne; Lothar Moerl; Lothar Backhauss
- Web page: https://patentgrep.com/patent/US5700572A

## CPC

- D01D 5/00: Formation of filaments, threads, or the like
- D01F 6/12: from polymers of fluorinated hydrocarbons
- Y10T 428/29: Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
- Y10T 428/2913: Rod, strand, filament or fiber
- D01D: MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
- D01F: CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

The invention provides a fiber material of PTFE and, optionally, hydrophilizing additives, for use in the production of diaphragms for the electrolysis of alkali chlorides, as well as for filter layers. The fiber material comprises fiber bundles and these, in turn, comprise individual microfibrils, there being irregularly shaped interstices between the microfibrils. The fiber material is produced in that a PTFE dispersion, consisting of a salt solution with PTFE particles and, optionally, hydrophilizing additives, is treated in a hot gas/vapor stream in a fluidized bed apparatus charged with inert solids. The method permits the fiber material to be produced also in larger quantities in an economic manner.

## Claims

### Claim 1

A fiber material, comprising:
PTFE; and
structural form of said PTFE presenting a plurality of fiber bundles, said fiber bundles including discrete microfibrils, said microfibrils in physical arrangement with one another within each of said fiber bundles to define irregularly shaped interstices between said microfibrils.

### Claim 2 (depends on 1)

The fiber material according to claim 1, further comprising a hydrophilizing additive.

### Claim 3 (depends on 2)

The fiber material according to claim 2, wherein said hydrophilizing additive includes an inorganic agent.

### Claim 4 (depends on 3)

The fiber material according to claim 3, wherein said inorganic agent is selected from the group consisting of zirconium dioxide, titanium dioxide, silicon dioxide, kaolin, aluminum oxide, magnesium oxide, magnesium hydroxide, and calcium carbonate.

### Claim 5 (depends on 2)

The fiber material according to claim 2, wherein said hydrophilizing additive includes a highly functionalized PTFE polymer-identical modifier.