CA1096093A

CA1096093A - Phosphonated fluorotelomers

Info

Publication number: CA1096093A
Application number: CA272,792A
Authority: CA
Inventors: James C. Fang
Original assignee: EI Du Pont de Nemours and Co
Current assignee: EIDP Inc
Priority date: 1976-03-02
Filing date: 1977-02-28
Publication date: 1981-02-17
Also published as: IT1086214B; FR2343000B1; GB1572863A; BR7701283A; JPS61353B2; DK62277A; FR2343000A1; AU2282177A; LU76864A1; AU508300B2; DE2709097A1; JPS52118431A; NL7702186A

Abstract

ABSTRACT
The phosphonated fluorotelomers of this inven-tion are, or can easily be made to be, hydrophilic. When blended with inert fibrous materials they can be used to make diaphragms for electrolytic cells, particularly for chlor-alkali cells used in the production of chlorine, hydrogen and sodium hydroxide from brine. Ion-exchange membranes can also be made from these fluorotelomers.
The fluorotelomers can be made by using free radical phosphonyl esters to terminate the polymerization of the selected fluorocarbons.

Description

~L~9~1~93 In co~mercial chlor~alkali cells u~ed ~or the producti~ of chlorine, hydrogen and sodium hydroxlde fro~
brine, asbestos diaphr~gms are ordlnar~ly used to separate the ano~rte a~d catholyte compartment~. Di~phrag~s of thl~
80rt are generAlly satisfactory, but their electrical reslsta~ce i~ hlgh and ~ells which use Ru~h ~laphragms there-fore require ~ore electrie current for operatio~ than ~8 de~lrable. Furth~ re, a~bestos dlaphragms ~reated with 10 certain ion-exehange re~in~ are described in U. S. Patent 3 J 853,721 - Darlington and Foster (1974).

SUMMARY OF ~HE INVENTION

The phosphonated ~luorotelome~rs Or the inventlon . , are tho~e represented by the ~ormula O O
Il , (1) Y10 - P - (X)n - I - ~4 : :

or O O O ~
\ 11 11 / \

(2) ~ X)~ - P\ /Z2 ~:
O O . ~

..... i ~ :

where Yl, Y2, Y3 and Y4 are the same or different and are alkyl radicals of 1-10 carbon atoms, alkyl radicals of 1-10 carbon atoms su~sti-tuted with at least one alkyl radical of 1-4 carbon atoms, or monovalent metals;
X is a :~omo- or cotelomeric moiety of at least one of (a) one or more monoeth~lenically unsaturated monomers fully sub-stituted with fluorine atoms or with a combination of at least one fluorine atom and chlorine or bromine atoms, and (b~ a per~luoroalkyl ~i.nyl ether whose alkyl group c:ontains 1-10 carbon atoms;
Zl and Z2 are the same or different and are divalent metals, alkylene radicals of 1~10 carbon atoms, or alkylene radicals of 1-10 ; carbon atoms substituted with at least one :~
alkyl radical of 1-4 carbon atoms, or Z2 is made up of Y1 and Y2; and n is 2-;00.
As used in formulas (1~ and (2~, "cotelomeric moiety" means a telomeric moiety composed o two or more different types of monomer units, and "homotelomeric moiety" means a telomeric moiety composed of one type of monomer units.
The term "fully substituted" means that few if ~6~3 any C-E bonds are found in the telomeric moiety.
Although preferred, the telomer need not be completely substituted.
The telomers of formula (1) can also be in the form of trivalent metal salts, which have a cross-linked structure in which one or two of the metal valences are taken by one fluorotelomer molecule and the remaining valences are taken by other fluorotelomer molecules.
The monovalent, divalent and trivalent metal salts o the fluorotelomers can be formed in situ in a chlor-alkali cell where tne fluorotelomer is used.
Those fluorotelomers of formulas (1) and (2) which are not hydrophilic or are only marginally hydro-philic can be made hydrophilic by converting them to the free acid forms or to metal salts, as will be described.
The phosphonated fluorotelomers preferred.for use according to the invention becausls they are easy to prepare and because they have good ion-exchange charac-teristics and low soIu~ility in cell liquors are those 20 of formula (1) where X is a telomeric moiety of tetrafluoroethylene (TFE); `
Yl, Y~, Y3, and Y4 are all ethyl or all butyl, or where Yl and Y2 are ethyl and Y3 and Y4 are butyl;
and n is 20-100.` ~ `
Also preferred for their low melting points and the ease with which diaphragms can be abricated with them are fluorotelomers of formula (1) where X is a cotelomeric moiety of TFE and a ~û~6~

perfluoropropyl vinyl ether in a weight ratio o~ 83/17, or a telomeric moiety of hexafluoropropylene;
Yl, Y2, Y3 and Y4 are all ethyl; and ~ is 20 - L00 .
Also preferred in some circumstances are fluorotelomers of formula (2) where X is a cotelomeric moiety of TFE and hexa-fluoropropylene (HFP) in a weight ratio o 5/1; - `
Z1 is ethylene and Z2 is diethyl; and n is 20-100.
Parts, percentages and proportions herein are by weight except where indicated otherwise. In act-~al usa, the preferred telomers are convexted to the corre-sponding sodium salts in an electrolytic cell.
In addition to the 1uorote10mers themselves, the invention also comprises processes for their prepa-ration in the ester, acid and salt forms, diaphragms and membranes made using them, and the use of such diaphragms and membranes.
DETAILED DESCRIPTION OF THE IN~VENTION
Unlike ordinary fluorotelomers, the fluoro-telomers of this invention are hydrophilic or can easily be made to be hydrophilic~ "Hydrophilic" in this sense means the telomers absorb water rather than r~pel it.
More specifically, "hydrophilic" means that the telomer has a water contact angle of 0 to about 50 ! as measured by the method and apparatus described on page 137 of "Contact Angle, Wettability and Adhesion~"

, 65:)~3 American Chemical Society, 1964.
The claimed hydropnilic fluorotelomers, when blended with inert fibrous materials and binders and fabricated into diaphragms, or when formed into a membrane preferably supported by an inert fabric, can-be used in ion-exchange procedures, especiall~ where hydrophilicity is desirable or essential. Such diaphragms used in chloral.cali cells, surprisin~ly ha~e far less electrical resistance than conventional asbestos diaphragms. As a result, cells using diaphragms con-taining the hydrophilic fluorotelomers of the invention can maintain chlorine, hydrogen and caustic production at the same levels obtained when asbestos diaphragms are used even though the cells operate at lower volta~es.
In addition, diaphragms made with these fluorotelomers in general are mare resistant to attack by electrolytic cell liquors, last longer and are more dimensionally stable than prior art asbestos diaphragms.
How the Phosphonated Fluorotelomers are Made The phasphonated 1uorotelomers of the inven-tion can be made by reacting a suitable monoethylenically unsaturated fluoromonomer with a compound capable of ;~
generating a phosphorous-containing free radical of the ~ ;
structure O
YO-P ~
OY
where Yl and Y2 are the same or different and preferably are al~:yl radicals of 1-10 30 ` carbon atoms or alkyl radicals of 1-10 carbon g3 atoms substituted with at least one alkyl radical of 1-4 carbon atoms.
Illustrative of the fluoromonomers which can be used are tetrafluoroethylene (TFE) monochlorotrifluoroethylene `
dichlorodifluoroethylene monobromotrifluoroethylene . dibromodifluoroethylene hexafluoropropylene (HFP) perfluoroalkyl vinyl ethers (whose alkyl groups contain l-lO carbon atoms) These fluoromonomers can be used singly to produce homo- :
telomeric forms, or can be used in combinations of two . or more to orm cotelomeric forms of the phosphonated fluorotelomers.
Illustrative of the compounds capable o~
generating the requisite phosphorous-containing free 20 radical are tetraalkyl hypophosphates (whose alkyl groups contain 1-lO carbon atoms) - tetraalkyl pyrophosphites (whose alkyl groups contain 1-lO carbon atoms) cycloalkyl hypophosphates (whose alkyl groups contain l-10 carbon atoms) cycloalkyl pyrophosphites (whose alkyl _7_ 19~

groups contain 1-10 carbon atoms) and compounds of the formula ~ .~ ~- .
8 ~ 1~ `
Y10 - IP P - ~ Y4 where Yl, Y2, Y3 and Y4 are defined as in formula (1).
Mixtures of such compounds can also ~e used.
10The reaction.of the fluoromonomer and free radical generating compound proceeds according to the ~-following illustrative equations:
OR OR jO
(41 2Ro-p-o-p-oR initiator ~ 2RO-P-OR
tetraalkyl free radical pyrophosphite ' O O O
Il 11` 11 . : .
2RO-P~ + fluoromonomer ~ RO-P~ Xt~-- P OR
OR OR OR -~ree radical telomer O O o (5) 2RO-P - P OR initiator > 2RO-P~
OR OR OR :
tetraalkyl free radical hypophosphate O O O
Il 11 11 .
--2RO-P~ ~ fluoromono~er ~O-P~ X~n-- P OR
OR OR OR
free radical telomer .

~;)9~ 3 The same reactions can be used to prepare the telomers of formula (2), usin~ cycloalkyl hypophosphates or cycloalkyl pyrophospites as free radical generating compounds.
The reactions described in equations t4) and (5) are carried out by first dissolvlng enough of the hypophosphate or pyrophosphite reactant in a halogenated hydrocarbon solvent to make a 1-50% by weight solution.
To this solution is then added 0.1%-10%, by weight, of a free radical initiator like di-t.butyl peroxide or azobisisobutyronitrile.
The solution is then placed in a pressure vessel and the fluoromonomer gas or liquid is added.
The amount of fluoromonomer added will depend on the telomer chain length desire ~i.e. the value of n in formulas (l) and (2)] and ordinarily is in the range of 2-500 moles for each two moles of pyrophosphite or hypophosphate.
The vessel is then sealed, heated to 50-300C, prefexably 60-120C and held there, with rocking, until the pressure in the vessel drops, which indicates completion of the reaction. The vessel is then opened, the dispersion of phosphonated fluorotelomer removed and the solvent stripped from the dispersion by evaporation.
The resulting product is washed in methanol, dried and is then ready for use.
The fluorotelomer thus isolated can vary in physical state from a viscous liquid to a waxy solid.
The mixed telomers of the invention, i.e., those in which Yl and Y2 are different from Y3 and Y4, -- ~0~6~

can be prepared according to the following illustrative equations:
Il 11 (6)CH3(CH2)3O - P - P - OCH2CH3 initiator~
.. . I I
CH3(CH2)3- O OCH2CH3 mixed tetraalkyl hypophosphate o O
Il ' li CH3(CH2)3O lo CH3CH2O-CH3(CH2)3-O CH3CH2 O

free radical free radical O O
Il .
CH3(CH2~3 O I CH3CH2O-P- ~ fluoromonomer CH3~CH2~3 -O CH3CH2-O
.

~

O O ~
Il ~1 C~3(CH2~3 o P~ X)-n- P--O--CH2CH3 CH3(CH2)3 O O-CH2CH3 --. . -- telomer ~ , The reaction described in equation (6) is carried out in the same way as those of equations (4) and (5).

--10-- , ,. :
~ :

~lC~6~

In the formation of the free radicals J some different terminal groups, such as carboxyl groups, may be introduced. However, this would not affect the ability of the described fluorotelomers which are still present to provide the advantages of the invention.
The mixed tetraalkyl hypophosphate reactant used in equation (6) can be prepared as described in Bull. Acad. Polon. Sci., Ser. Sci. Chim., 13, 253 (1965) and in Z. ~norg. Allg. Che., 288, 171 (1956).
The metal salts of the phosphonated fluoro-telomers can be prepared by hydrolyzing a telomer to the free acid form, then replacing the hydrogens of the carboxyl groups with metals ~y metathesis.
Monovalent, divalent or tri~alent metals can be used to form a fluoxotelomer salt. Illustrative of such metals are sodium manganese potassium iron lithium cobalt calcium copoer barium zinc magnes;um cadmium aluminum Ordinarily, the fluorotelomers are used in the ester form to make diaphra~ms for chlor-alkali cells.
The ester form is converted to the sodium salt form when the diaphragm comes into contact with sodium hydroxide in the cell liquor. The ester orm is also readily converted to the acid form by hydrolysis such as with suitable acids.

'~

How Diaphragms o the Telomers are Made For whatever use, a diaphragm using a phosphonated fluorotelomer of the invention can be prepared from a composition which comprises (a) one or more fluorotelomers of formula (l);
(b) a fibrous material which will act,as a base for the diaphra~m;
(c) a fl~oropolymer binder material; and (d) a li~uid carrier.
This composition can also contain conventional adjuncts such as wetting agents, surfactants, defoamers and the like, in the usual amounts, `
A diaphragm can be made from such a composition by first deagglomerating the fibers of (b) and then forming a mat of the fibers by removing the carrier, pre~erably by a papermaking technique. The mat is then heated to the binder fusion temperature~ to give a coherent structure which can be used directly for whatever purpose intended.
The diaphragm mat can be formed directly on the ,~
cathode screen of the electrolytic cel,l in which it is to be used and then heated to fuse the binder. The diaphragm thus made can be used directly, without further ;~
treatment. Diaphragms made in this way must meet manu- ;
facturer's specifications regarding permèability, current efficiency and dimensional stability. These specifications vary with the manufacturer, the ty~e of cell being used, electrical current demands of the cell, and like factors.
One skilled in the diaphragm making art will use the same 30 skills in preparing diaphragms from the compositions of ;

this invention that he does in preparing conventional asbestos diaphragms.
Any fibrous material can be used which can withstand the baking temperature to be used and which resists attack by the environment in which the membrane is to be used. Illustrative of such materials are asbestos glass fibers fibers of such fluoropolymers as polytetrafluoroethylene (PTFE) or TFE/HFP copolymers potassium titanate fibers.
Mixtures of such fihrous materials can also be used.
Asbestos is the preferred fibrous material for use in electrolytic cell diaphragms. Especially preferred is a chrysotile asbestos whose fibers have an average diameter of about 200A (as measured by electron microsco~y) and an average length of about 70 mm. Prefe~ably, the asbestos fibers are completely or substantially completely coated 2~ with fluorotelomers of the invention.
Similarly~ the fluoropolymer to be used as a binder material can be any which resists attack by the environment in which it is to be used. Illustrative are PTFE
TFE~HFP copolymers (all monomer ratios).
polyvinyl fluoride polyvinylidene fluoride vinylidene fluoride/HFP copolymers (all monomer ratios).

~!96[3~3 Mixtures of binder materials can also be used.
In electrolytic cell diaphragms, the TFE/I~FP
copolymers are preferred as binder materials because of their inert nature.
The carrier can be any liquid which will not significantly affect the chemical or physical characteris-tics of t~e diaphragm. Illustrative of such liquids arewater chlorinated hydrocarbons 10methanol hexane brine.
~hen the composition is to be used to make an electrolytic cell diaphragm, brine solution of 15% NaCl in ~ater is preferred as a carrier because it helps keep the fibrous material in suspension.
The components of the compo~ition are preferably present in the foLlowing concentrations:
(a) Telomer - lO-90~ by weight of the total of 20(a) and (D), even more preferably 40~60~r (b) Binder - 10-90~ by weight of the total of (a) and (b), even more preferably 40-60~;
(a) plus (b) constituting 10-90~ r preferably 20-25%, by weight of the total of (a), (b), and (c);
(c) ~ibrous material - lO-90~ by weight of the total of (a), (b), (c), preferably 70-80%;
(d) Carrier - the remainder.
The composition will contain 0.01-3~, by weight, of solids, preferably about 1~.

30In a variant of t~is co~osltion~ an appropriate amount of the telomer and binder can be mixed together, and the fibrous material and carrier can be added to this mixture just before the resulting composition is to be used to prepare a diaphragm.
In such a composition, the telomer and binder are each present in concentrations of 1-9~%, preferably 10-30%, by weight of the total of telomer and binder.
Although it is expected that the phosphonated fluorotelomers of the invention will be used primarily to fabricate diaphragms for electrolytic cells, especially chlor-alkali cells, ~ ey can also be used to prepare membranes for use as the separating means for separating diverse substances, either electrolytically or nonelectro-lytically. For instance, they may be used in ion-exchange proceduxes such as the desalinization of sea water, and to prepare semipermeable membranes for use in osmotic procedures and in dialysis, including Donnan dialysis~
The telomers can also he u,sed to pre~are batterv se~ara- ;
tors, especially for use in alkaline cells. Fluorotelo-mers of formulas (1) and (2) where n is 2-20 can also be used to passivate metals.
Membranes differ from diaphragms in that mem-branes are substantially hydrolytically impermeable, selectively passing either cations or anions, depending on the perm-selectivity of the membrane. Semipermeable membranes also have minute porosity permitting the passage of liquids but inhibiting the passage of rela-tively large species such as some colloids. Diaphragms do pass substantial amounts of fluid while inhibiting the passage of anions or cations.

-, .~ .. ~, , ~3 ~ embranes may be formed and used accordins to techniques kno~n in the art. Phosphonated fluorotelomers of the invention may be formed into membranes~ preferably about 0.l-0.25 mm thick in contrast to typical diaphragm thicknesses of 2,5 mm. Such thin membranes would normally be formed on a fabric, preferably of open mesh design, of material which is inert to the operating environment.
Fluorocarbon polymers such as PTFE are suitable to support phosphonated fluorotelomers of the invention to be used in chlor-alkali cells.
The following examples illustrate the invention.
In each example, the diaDhra~ms prepared were used with a cathode-to-anode spacing o. 0.635 cm (~ in.). Typical asbestos diaphragm cells of the prior art require 3.5-3.7 volts to obtain a current density of 0.204 amperes per square centimeter with that spacing. Although the diaphragms of the examples are formed as sheets and then placed into electrolytic cells r similar results are zo obtained when the diaphragms are formed on a cathode screen in the c~
EXAMPL~ ONE
~ .
(A~ ~ pressure vessel was charged with (1) trichlorotrifluoroethane ~ 160 parts solution o~ 6.45 parts of tetraethyl pyrophosphite in 20 parts of trichloro-tri~luoroethane t3) a solution or 2 parts of ditertiary butyl peroxide - `
in 20 parts of trichloro-trifluoroethane (4) tetrafluoroethylene50 parts ,:

-16- ~-. .

The charge was blanketed ~ith nitrogeng the vessel ~ealed and the temperature Or the charge raised to 100C a~d held there for two hours. ~he te~perature of th0 charge was then rai~ed to 120C, held there for t~o hours, the~ raised stlll again to 140C and held at ~hat temper~ture for two hours.
At that polnt, a drop ln pre~ure inside the ves~el ~ndlcated completion of the reactlon.
me ves~el W~5 ope~ed, the cont~nts removed and placed in a stil~, where the solvent was dlstilled of~ at 40-50 ~ .
The resulting waxy solid wa~ washed twice with ~ethanol and then drled under vacuum.
(B) The following were prepared:
tl) ~ solutio~ of 363 parts o~ 60dium chlorlde ln 2420 pdrt8 Or distl~:Led water.
(2) a mlxture of (a) 5.5 parts oX a TFEhH~P 85/15 copoly~er disper~lonJ 55~ so:Lids ln water, and (b) 3.03 parts o~ the product of (A) in 30 part~ o~ lsopropallo L.
Solution ~1) wa~ pLaced ~n a blender, to whleh wa~ then ~ :~
added 24.2 part~ of asb2~tos fibers (average dia~eter 200A, average length 70 mm, 601d by J~hns-Manvllle Co-. aæ :
CHLORBESTOS~ ~P-25). ~xture (2) ~a~ then added. The ~harg~
~as blended at medium spe~d rOr 2 minutes and the~ spar~ed ~ ~
~lth air ~or two hour~ to ~eagælo~erate the 3sbe~tos ~iber~. ;-This mixture wa~ the~ d~lute~ with ~n equal * denotes trade ~rk ~7 - :

;ri ', . ` : ' ' . : . . ; . ' ': ' volume of distilled water and poured into a sheet mold, where the liquid was drawn off under a vacuum of 250 mm.
The resulting mat was washed by drawing 2000 parts of distilled water through it and was then dried at 95C
for one hour and then baked at 275C for 30 minutes, to give a product 2.5 mm thick.
The mat was then boiled in 5~ aqueous sodium hydroxide for 2.75 hours and dried.

(C) The mat prepared in (B) was put in the diaphragm position on the cathode of a chlor-alkali cell, where, in operation, it required an average voltage of 3.7 to achieve a current density of 0.204 amperes per square centimeter of diaphragm area.
EX~MPLE TWO
(A) A fluorotelomer was prepared as described in Example 1 (A) using the following charge (1) a solution of 16.5 parts of dibutyl-diethyl hypophosphate in 200 par~s o trichloro-trifluoroethane (2) azobisisobutyronitrile 4.1 parts

(3) tetrafluoroethylene S0 parts and holding the reaction temperature at 65C for three hours followed by 90C for three hours.
(B) Asbestos fibers of the type used in Example 1 (B~, 3.7 parts, and 370 parts of distilled water were placed in a blender. To this was then added a mixture of dispersion of (A) 6095 parts methanol 40 parts dispersion of a TFE/HFP 85/15 copolymer in water(55% solids) 1.11 parts distilled water 20 parts -6~Y13 The charge was blended at low speed for 10 minutes and the resulting slurry was then diluted with 1558 parts of distilled water. The liquid was drawn from this slurry in a Buechner funnel under a vacuum of 250 mm.
The resulting mat was dried under light pressure at 25C for 5 minutes, th~n at 95C for 30 minutes, and finally baked at 275C for 30 minutes, to give a product 2.5 mm thick.

The mat was then boiled for 90 minutes in 5%
aqueous sodium hydroxide~
- :
(C) The mat prepared in (B) was put in the diaphragm position on the cathode of a chlor-alkali cell, where, in operation, it required an average voltage of 3.26 to achieve a current density of 0.204 amperes per square c~ntimeter of diaphragm area.
Example 2 can be repeated except that the tetra1uoroethylene used in (~) is replaced with an èqual amount of a 50/16 mixture of tetrafluoroethylene and bromotrifluoroethylene. Results will be substan-tially the same.

EXAMPLE THREE
(A) A fluorotelomer was prepared as described in ~xample 1 (A) using the following char~e (1) a solution of 12 parts of tetraethyl pyrophosphite in 120 parts of trichlorotri-fluoroethane (2) a solution of 3.65 parts of di-t. butyl peroxide in 40 parts of trichlorotri-fluoroethane 3~ ~
:

, . . . .
::. . :.

(3) a mixture of 50 parts of tetrafluoroethylene and 10 parts of perfluoro-propyl vinyl ether and holding the reaction temperature at 100C for two hours, at 120C for another two hours, and then at 140C
for two hours.

(B) A slurry of Distilled water 2420 parts Sodium chloride 263 parts Asbestos (same type as in Example 1)24.2 parts was sparged with air for two hours. To the slurry was added a dispersion of ~1) Dispersion of the telomer of (A), 3.03 parts in 14.91 parts of methanol (2) TFE/HFP 85/15 copolymer powder 3.03 parts The slurry was spa.rged with air for 30 minutes and then blen~ed in a blender for one minute at medium speed.
A mat was prepared from the slurry by drawing off the liquid in a sheet mold under a vacuum of 250 mm o mercury. The mat was washed by drawing 2000 parts of distilled water through it, was pressed ketween sheets of absorbent paper and then held at 135C for five minutes, still between the sheets of paper.
The resulting dry mat, 1.5 mm thick, was then baked for 30 minutes at 275C.
(C) The mat prepared in (B) was put in the diaphragm position on the cathode of a chlor-alkali cell, where, in ..

~Q96~93 operation, it required an average voltage of 2.96 to achieve a current density of 0.129 amperes per square centimeter.
Example three can be repeated except that the fluoxomonomer charge in (A) is replaced with an equimolar amount of an 30/20 mixture of tetrafluoroethylene and hexafluoropropylene. Results will be substantially the :~^
same.
E ~ IPLE FOUR
(A) A fluorotelomer was prepared as described in Example 1 (A) using tlle followin~ charge (1) a solution of 12 parts of tetraethyl pyrophosphite in 120 parts of trichlorotri-fluoroethane (2) a solution of 3.65 parts of t. butyl perpivalate in 40 parts of trichlorotri~luoro-ethane (3) a mixture of 50 parts Oc TFE
and 15 parts of HFP
and holding the reaction temperature at 60C for 2 hours ~0 and then at 80C for 2 hours.
(B) A slurry of Distilled Water2420 parts Sodium chloride263 parts Asbestos (same type as in Example 1) 24.2 parts was sparged with air for two hours. To the slurrv was added a dispersion of (1) a dispersion of the telomer of (A),

4.54 parts ln 50 parts OL methanol (2) TFE~HFP 18/15 copoly~er powder 1.90 parts 6~)~3 The slurry was-sparged with air for two hours an~ then blended for one minute in a blender at medium speed.
A mat was prepared from the slurry as in Example 3(B).
(C) The mat prepared in (B) was put in the diapllragm position on the cathode of a chloralkali cell ! where, in operation, the average voltages indicated below were required to achieve the current densities indicated.

Volts Amperes!cm2 2.86 0.129 3.04 0.182 3.10 0.204 Such results are also obtained when the diaphragm is formed by similar techniques directly on the cathode, ~`
.

~22-

Claims

CANADA, U.K., AUSTRALIA, S. AFRICA, ITALY, IRELAND

WHAT I CLAIM IS:

1. A fluorotelomer represented by the structure or where Y1, Y2, Y3 and Y4 are the same or different and are alkyl radicals of 1-10 carbon atoms alkyl radicals of 1-10 carbon atoms substi-tuted with at least one alkyl radical of 1-4 carbon atoms, or monovalent metals;
X is a homo- or cotelomeric moiety of at least one of (a) one or more monoethylenically unsaturated monomers fully substituted with fluorine atoms or with a combination of at least one fluorine atom and chlorine or bromine atoms, and (b) a perfluoroalkyl vinyl ether whose alkyl group contains 1-10 carbon atoms;
Z1 and Z2 are the same or different and are divalent metals, alkylene radicals of 1-10 carbon atoms, or alkylene radicals of 1-10 carbon atoms substituted with at least one alkyl radical of 1-4 carbon atoms, or Z2 is made up of Y1 and Y2;
n is 2-500; and salts of such fluorotelomers with one or more trivalent metals.

2. A salt of the fluorotelomer of claim 1, formula (a), with a trivalent metal.

3. The fluorotelomer of claim 1 wherein X is a telomeric moiety of tetrafluoroethylene.

4. The fluorotelomer of claim 1 wherein Y1, Y2, Y3 and Y4 are ethyl.

5. The fluorotelomer of claim 1 wherein Y1, Y2, Y3 and Y4 are butyl.

6. The fluorotelomer of claim 1 wherein Y1 and Y2 are ethyl and Y3 and Y4 are butyl.

7. The fluorotelomer of claim 1 wherein Y1, Y2, Y3 and Y4 are sodium.

8. The fluorotelomer of claim 1 wherein n is 20-100.

9. The fluorotelomer of claim 1 wherein Y1 and Y2 are ethyl, Y3 and Y4 are butyl, X is a telomeric moiety of TFE and n is 20-100.

10. The fluorotelomer of claim 1 wherein Y1, Y2, Y3 and Y4 are sodium, X is a telomeric moiety of tetrafluoroethylene and n is 20-100.

11. The fluorotelomer of claim 1 wherein X is a cotelomeric moiety of tetrafluoroethylene and perfluoro-propyl vinyl ether.

12. The fluorotelomer of claim 1 wherein X is a cotelomeric moiety of tetrafluoroethylene and perfluoro-propyl vinyl ether; Y1, Y2, Y3 and Y4 are ethyl; and n is 20-100.

13. A composition suitable for preparing a diaphragm for an electrolytic cell containing a cell liquor, comprising (a) 10-90%, by weight of the total of (a) and (b), of at least one telomer according to claim 1;
(b) 10-90%, by weight of the total of (a) and (b), of a fluoropolymer binder;
(a) plus (b) constituting 10-90% by weight of the total of (a), (b) and (c), (c) 10-90%, by weight of the total of (a), (b) and (c) of a fibrous material resistant to attack by the cell liquor;
and (d) a liquid carrier.

14. The composition of claim 13 where, in the fluorotelomer of (a), X is a telomeric moiety of tetrafluoroethylene.

15. The composition of claim 13 where, in the fluorotelomer of (a), Y1, Y2, Y3 and Y4 are ethyl.

16. The composition of claim 13 where, in the fluorotelomer of (a), Y1, Y2, Y3 and Y4 are butyl.

17. The composition of claim 13 where, in the fluorotelomer of (a), Y1 and Y2 are ethyl and Y3 and Y4 are butyl.

18. The composition of claim 13 where, in the fluorotelomer of (a), n is 20-100.

19. The composition of claim 13 wherein the binder in (b) is a copolymer of tetrafluoroethylene and hexafluoropropylene.

20. The composition of claim 13 wherein the fibrous material in (c) is asbestos.

21. The composition of claim 13 wherein the carrier in (d) is brine.

22. The composition of claim 13 where, in the fluorotelomer of (a), X is a telomeric moiety of TFE, Y1 and Y2 are ethyl, Y3 and Y4 are butyl and n is 20-100;
the binder in (b) is a tetrafluoroethylene/hexafluoro-propylene copolymer; the fibers in (c) are of asbestos and the carrier in (d) is brine.

23. The composition of claim 13 where, in the fluorotelomer of (a), X is a cotelomeric moiety of tetra-fluoroethylene and perfluoropropyl vinyl ether.

24. The composition of claim 13 where, in the fluorotelomer of (a), X is a cotelomeric moiety of tetra-fluoroethylene and perfluoropropyl vinyl ether, Y1, Y2, Y3 and Y4 are ethyl and n is 20-100; the binder in (b) is a tetrafluoroethylene/hexafluoropropylene copolymer; the fibers in (c) are of asbestos and the carrier in (d) is brine.

25. A composition consisting essentially of (a) 1%-99%, by weight of the total of (a) and (b), of a fluorotelomer according to claim 1;
and (b) 1%-99%, by weight of the total of (a) and (b), of a fluoropolymer.

26. An electrolytic cell diaphragm prepared from the composition of claim 13 by forming a mat from the composition by removing the carrier, heating the mat to a temperature at which the fluoropolymer fuses, and then bringing the resulting product into contact with an aqueous solution of sodium hydroxide.

27. An electrolytic cell diaphragm prepared from the composition of claim 22 by forming a mat from the composition by removing the carrier, heating the mat to a temperature at which the fluoropolymer fuses, and then bringing the resulting product into contact with an aqueous solution of sodium hydroxide.

28. An electrolvtic cell diaphragm prepared from the composition of claim 24 by forming a mat from the composition by removing the carrier, heating the mat to a temperature at which the fluoropolymer fuses, and then bringing the resulting product into contact with an aqueous solution of sodium hydroxide.

29. The electrolytic cell diaphragm of any one of claim 26, claim 27 and claim 28 prepared directly on the cathode of the cell.

30. A process for preparing the fluorotelomer of claim 1, comprising bringing at least one of (a) one or more monoethylenically unsaturated monomers fully substituted with fluorine atoms or with a combination of at least one fluorine atom and chlorine or bromine atoms, and (b) a perfluoroalkyl vinyl ether whose alkyl group contains 1-10 carbon atoms, into contact with a compound capable of generating a free radical of the structure where Y1 and Y2 are the same or different and are alkyl radicals of 1-10 carbon atoms or alkyl radicals of 1-10 carbon atoms sub-stituted with at least one alkyl radical of 1-4 carbon atoms, under conditions suitable for reaction.

31. A process according to claim 30 wherein the fluorotelomer is subsequently hydrolyzed to convert Y1 and Y2 to hydrogens by contact with acids.

32. A process according to claim 30 wherein the fluorotelomer is subsequently converted to the salt form wherein Y1 and Y2 are metals by contact with a salt of the selected metals.

33. In a process for the electrolytic pro-duction of chlorine from brine, the improvement comprising keeping the chlorine produced at the anode separated from the hydrogen and sodium hydroxide produced at the cathode with a diaphragm of any one of claim 26, claim 27 and claim 28.

34. An electrolytic cell having a diaphragm of any one of claim 26, claim 27 and claim 28.

35. An electrolytic cell membrane comprising a phosphonated fluorotelomer of claim 1 supported by a fabric of polyfluorocarbon.

36. In a process for separating diverse substances from each other by dialysis, osmosis or ion-exchange, the improvement comprising using as the separating means a membrane prepared from the composition of claim 13 by forming a mat from the composition by removing the carrier and then heating the mat to the fluoropolymer binder fusion temperature.