US1720670A

US1720670A - Manufacture of ultrafilter membranes

Info

Publication number: US1720670A
Application number: US660179A
Authority: US
Inventors: Duclaux Jacques
Original assignee: Individual
Current assignee: Individual
Priority date: 1922-09-11
Filing date: 1923-08-30
Publication date: 1929-07-16
Anticipated expiration: 1946-07-16
Also published as: GB203714A; FR567970A

Description

MANUFACTURE OF ULTRAFILTER MEMBRANES Filed Aug. 30, 1923 Patented July 16, 1929.

JACQUES DIJ'CLAUX,

OF PARIS, FRANCE.

MANUFACTURE OF ULTRAFILTER IEHBRAN ES.

Application filed August a0, 192;, serum no.

It is well known that membranes called ultra-filters comprising cellulose'estcr films, have been used for some .years in scientific research laboratories. Several processes for. 6 their preparation have been described, but

these processes, which are suitable for laboratories, are too costly or too complicated to be of industrial application. They are not suited for use in preparing for instance, 10 several hundred square metres of ultra-filter membrane, as it is necessary to do in industrial operations.

The invention has for its object a process'for the production of these membranes in large quantities. This process hasthe advantage of being particularly economical owing to the fact that most of the solvent used for dissolving the cellulose ester can be recovered and used over again. The invention also includes certain improved membrances of the type later described.

-According to this invention I form the cellulose ester films constituting the ultrafilter on an unrolling strip of smooth cloth 2 which is guided by rollers so as to dipfirst into a solution of cellulose ester and subsequently into a coagulating liquid.

Referring to the appended drawing illustrating diagrammatically, as an example, an apparatus for carrying out the process, the object of the invention. i

The membrane, of cellulose ester and particularly of nitro cellulose, is forced upon a strip of cloth of any length, carried onroller's. Starting from a first storage roll a, the band dips first into a trough 6 containing the solution of. cellulose ester or collodion, then it passes upon a guiding roller 0 and issues vertically'from the trough, carrying .by adhesion a certain quantity of collodion. At a certain distance above the trough, the strip of cloth, which has begun to dry, meets a system of rollers d and e which guide it through a vat f full of a coagulating liquid, for instance, water, in which it proceeds for a while. It emerges from it completely hardened and freed from most of the solvent and is rolled up upon a last roll In the example illustrated on the drawing, the strip passes only once in the 'vat filled with the coagulating liquid. It is evident, however, that it is possible, by means of other rollers, to lengthen its path in this liquid to ensure its more thorough washing.

The single vat may also be replaced by sev- 660,178, and in Frauoe September 11, m2.

eral successive vats, with. a methodical eirculation' of coagulatin liquid.

The s eed of trans ation must be sufli- 'ciently s ow for the collodion carried awa by the strip of cloth to be solidified before arriving at the roller d or elseit might stick to the latter. For greater security,

this rolle'r may be covered with'cloth, blotting paper or any other porous substance mpregnated with the coagulating solution; in this manner, adhesion is .cqmpletely avo ded, providedthat the solution impregnatmg the roller is frequently renewed.

The recovery of the solvent of the cellulose ester may be effected in two ways. A first portion of this solvent evaporates durmg. the passage of the cloth between the collodion trough b and the roller d. The vapours being heavier than air, fall .vertically; 1t 1s suflicient to surround this part of the apparatus with a kind of casingand to collect at the lower portion the air loaded with vapours. Another portion of the sol-- vent is carried by the clothand is found dissolved in the coagulating liquid, from which 1t can be extract (1. N

' It is possible to add to the machine so constructed an arrangement permitting the control of the uniformity of the membranes. It

suifices for this to add a coloring matter to the liquid contained in the coagulation vat.

Variations in the textureo r in the thickness of the filter membrane will then be represented by difierences in coloration which are at once perceptible. I

In the method of manufacture of ultrafilter membranesfwhich has just been descrlbed, the strip of cloth acts merely as su port of the cellulose ester film which .is t e filtering element that is to say the film is supported in andspans the open mesh of the weave. The passage of this. strip of cloth 1n the collodion trough has simply for its object the impregnation of the cloth. It may be replaced by any other arrangement conducive to the same result; for instance, the impregnation may be obtained in causing, by means. of a nozzle, the collodion to flow on the cloth in a jet or thin film, either on both sides or on one side only.

Before passing into the machine which impregnates it with collodion, the cloth strip may receive a preparation adaptedto mo ify its filtering properties; it may .for instance; be n oistened'with water ora solution having for its purpose to-modify later on the filtering properties of the cellulose ester film.

the impregnated cloth is immersed in a coagulating bath.

2. The art of making ultra filter-membranes which comprises passing cloth through a solution of nitrocellulose of a consistency that will adhere to the cloth and fill the mesh thereof, removing the cloth from said solution, permitting solvent to evaporate until the nitrocellulose coating has solidified and the impregnated cloth does not adhere to a roller moistened with a coagulant for said nitrocellulose solution, and passing said cloth throu h a coagulating solution.

3. The art of making ultra-filter membranes which comprises passing cloth through a solution of nitrocellulose of. a consistency that will adhere to the cloth and fill the mesh thereof, removing the impregnated cloth from said solution, permitting solvent to evaporate until the nitrocellulose coating has solidified and the impregnated cloth does not adhere to a roller moistened with Water, and passing said cloth through water until the nitrocellulosecoating has completely hardened.

- In'testimony that I claim the foregoing as my invention, I have signed my name.

' JACQUES DUCLAUX.