DE1696259C3

DE1696259C3 -

Info

Publication number: DE1696259C3
Application number: DE1696259A
Authority: DE
Inventors: Philipp Dr. 8520 Erlangen Jaeger
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 1951-01-28
Filing date: 1951-01-28
Publication date: 1974-11-28
Also published as: DE1696259B2; DE1696259A1

Description

peraturen zwischen 450 und 550⁰C und einer Behandlungsdauer von 15 bis 60 Minuten noch biegsame und in 30"/qiger KOH schwach quellende Papiere herstellen. Bei entsprechender Wahl der Behandlungsdauer kann jedoch auch noch bei Temperaturen von 300 und 700° C getempert werden.temperatures between 450 and 550 ⁰ C and a treatment time of 15 to 60 minutes more flexible and produce low swelling in 30 "/ qiger KOH papers. With an appropriate choice of the duration of treatment, however, may be annealed even at temperatures of 300 and 700 ° C.

An Hand des nachstehenden Beispiels soll die Erfindung noch näher erläutert werden.The invention is to be explained in more detail using the example below.

Rhodesischer Asbest T 38 wurde zunächst in einem Windsichter ohne Zugluft zerrissen und anschließend zweimal mit 15 m^s/h Zugluft gesichtet. 15 g des so gesichteten Asbestes wurden dann in 750 ml Wasser suspendiert und drei Minuten in einem Mixer behandelt. Die Behandlung im Mixer ist deshalb erforderlich, weil das gemäß diesem Ausführungsbeispiel hergestellte Asbestpapier als Gassperre zwischen Elektrolyt- und Gasraum in Brennstoffelementen eingesetzt werden soll; wie sich nämlich gezeigt hat, lassen sich gasdichte Papiere nur mit Asbestfasern bestimmter Länge erreichen.Rhodesian asbestos T 38 was first torn up in an air sifter without drafts and then ^{sighted twice with 15 m s} / h drafts. 15 g of the asbestos thus sighted were then suspended in 750 ml of water and treated in a mixer for three minutes. The treatment in the mixer is necessary because the asbestos paper produced according to this embodiment is to be used as a gas barrier between the electrolyte and gas space in fuel elements; As has been shown, gas-tight papers can only be achieved with asbestos fibers of a certain length.

Der so aufbereitete Asbest wurde über einen Zeitraum von 4 Tagen mit 6 η KOH bei 90° C ausgelaugt und anschließend mit destilliertem Wasser so lange gewaschen, bis der pH-Wert der Asbestmasse etwa 9 betrug. Aus der Asbestmasse wurde auf einem Blattbildner ein 375 cm² großes Asbestpapier hergestellt und dieses wurde dann eine Stunde lang bei 450° C getempert. Wie die Druckprüfung gezeigt hat, sind derart hergestellte Asbestpapiere, die eine Flächendichte von 40 mg/cm^s haben, bis über 20 N/cm⁸ (1 atü) gasdicht und mechanisch sehr stabil.The asbestos prepared in this way was leached with 6 η KOH at 90 ° C. over a period of 4 days and then washed with distilled water until the pH value of the asbestos mass was about 9. ^{A 375 cm 2} asbestos paper was produced from the asbestos mass on a sheet former and this was then tempered at 450 ° C. for one hour. As the pressure test has shown, asbestos papers produced in this way, which have a surface density of 40 mg / cm ^s , are gas-tight up to over 20 N / cm ⁸ (1 atm.) And are mechanically very stable.

ίο Die Gasdichtigkeit der Asbestmembranen war auch nach 5000 Stunden Betriebszeit in Brennstoffelementen bei einer Temperatur von 70° C und 6 η KOH als Elektrolytflüssigkeit noch vorhanden. Eine Zerfaserung der Membranen trat unter den oben-ίο The gas tightness of the asbestos membranes was even after 5000 hours of operation in fuel elements at a temperature of 70 ° C and 6 η KOH still present as electrolyte liquid. A fraying of the membranes occurred under the above

is genannten Betriebsbedingungen nicht ein.is not mentioned operating conditions.

Die gleichen Ergebnisse wurden mit Asbestmembranen mit einer Flächendichte von 20 mg/cm² erreicht.
Die Verwendung der neuen Asbestmembranen istThe same results were achieved with asbestos membranes with an areal density of 20 mg / cm ² .
The use of the new asbestos membrane is on

ao nicht auf Brennstoffelemente beschränkt. Beispielsweise können sie auch als Diaphragmen in Elektrolyseuren und Akkumulatoren eingesetzt werden.ao not limited to fuel elements. For example they can also be used as diaphragms in electrolysers and accumulators.

Claims

I 696 259 In order to prevent the properties of asbestos bodies from being influenced by plastic binders

1. A process for the production of porous, bonded, asbestos disks, in particular asbestos disks, can be drawn upon the addition of such binders. For the production of binder-free Asmembranen, in which the asbestos disks at 5 best bodies, which can be used, for example, as diaphragms of increased temperature up to 700 ⁰ C in the electrolysis, can be characterized in that asbestos fibers cleaned according to the German patent with alkali or alkaline earth - 148 946 the asbestos bodies are pretreated at elevated temperature lihydroxide solutions that are tempered, namely at 600 to 700 ° C. These asbestos fibers an asbestos disk is formed 10 Asbestos bodies produced in this way are, however, with regard to and that this asbestos disk still has mechanical strength at temperature is not tempered completely from 300 to 700 ° C. thinking.

2. The method according to claim 1, characterized in that the object of the invention is to provide a method for indicates that the asbestos fibers with NaOH production of porous asbestos discs, in particular or KOH solutions at a pH value of 15 asbestos membranes, at which on one at least 8 are pretreated. The addition of a binder can be dispensed with

3. The method according to claim 1 or 2, characterized and in the asbestos discs with - compared to characterized in that the asbestos fibers are made with asbestos baskets produced by known processes Pre-treat with a pH value of 8 to 13 - further improved mechanical stability be delt. a ° can be obtained.

4. The method according to any one of claims 1 This is achieved according to the invention in that to 3, characterized in that the pretreated asbestos fibers with alkali or alkaline earth hydrates Asbestos fibers are pretreated at temperatures of 450 hydroxide solutions that from these can be tempered up to 550 ° C. Asbestos fibers an asbestos disc is formed and

5. The method according to one or more of the 35 that this asbestos disc at temperatures of 300 Claims 1 to 4, characterized in that tempering is carried out at up to 700 ° C.

the tempering over a period of 15 to As starting material in the new process

60 minutes is carried out. drive purified asbestos fibers that are used free

of undigested fiber bundles and impurities

30 slopes, for example crude and rock fragments

chen, are. The cleaning of the commercially available

Raw asbestos fibers can in a manner known per se by slurrying in water and / or by

The invention relates to a method for the production of multiple treatment in the wind sifter or hydro

production of porous, binder-free asbestos disks, including cyclone.

special asbestos membranes, in which the As- pure asbestos fibers can also be replaced by multiple

best windscreens at elevated temperatures of up to 700 ° C, followed by several days

are tempered. Leaching in hot, aqueous KOH or NaOH,

The production of asbestos discs, asbestos paper, for example 6 η KOH, can be obtained. The fore and asbestos membranes are usually done in 40 part of this cleaning process is that the way that asbestos fibers and the resulting alkaline treatment is an aqueous suspension, separated pretreatment with alkali or alkaline earth binding agent is allowed to attach to the fibers and makes hydroxide solutions superfluous. In this case, the water required from the slurry formed in this way is then separated again from the adhering lye before the tempering. The properties of the asbestos fibers are not completely washed out of the asbestos present after drying and pressing. The pH value of the washing liquor must not drop below 8, but not be greater than 13,
applied binders determined. However, completely pure asbestos fibers must be used before

A heat treatment with alkaline solutions is usually used as the binder

aqueous latex of a butadiene-styrene, butadiene 50 are pretreated. Are particularly suitable for this

Acrylic acid nitrile or a polychioroprene aqueous solutions of the alkali metal hydroxides, in particular

Tschuks, whereby for economic reasons a Bu, NaOH or KOH solutions with a pH value

tadiene-styrene rubber is preferably used. of at least 8, but solutions of

Asbestos papers produced in this way and containing plastic are used. the

and asbestos membranes have only a low volume. The pH value of the alkaline solutions should, as already, be low

menporosity and are mentioned as excellent seals, are between 8 and 13,

suitable. For various purposes, both of which surprisingly

for example, as a gas barrier between the electrolyte-occurring solidification of the asbestos fibers depends on both

and gas space in fuel elements, they depend on the temperature as well as on the time. the

but completely unsuitable. 60 Degree of solidification increases with increasing temperature

From the German patent ^Λ < 596 241 it is and the treatment time becomes longer. Known as asbestos membranes in fuel elements, the asbestos paper is becoming more and more brittle and is showing the need to use those in which the plastic used as binding water only has a very low swelling capacity, only a fraction or none at all. Accordingly, you will be each used so far, namely 0.5 to 6 6 * Weil temperature and time to the desired percent by weight, based on the weight of the asbestos properties of the asbestos discs, papers and stes. In this way, a sufficient volume of membranes can be deposited.
menDorosity reaches willow. As tests have shown, at tem-