(Co)polymerization process of fluoro-containing monomers for...

Details (Co)polymerization process of fluoro-containing monomers for... (Co)polymerization process of fluoro-containing monomers for...

2000-05-24

2002-11-19

Zitomer, Fred (Department: 1713)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

At least one aryl ring which is part of a fused or bridged...

C524S380000, C524S392000, C524S462000, C526S206000, C526S227000, C526S230500, C526S232100, C526S242000, C526S911000

Reexamination Certificate

active

06482882

ABSTRACT:

The present invention relates to (co)polymerization processes of monomers for obtaining polymers containing hydrogen and fluorine.
In particular it relates to (co)polymerization processes having improved reaction rate, i.e., higher polymerization yield.
(Co)polymerization processes of unsaturated perfluoromonomers, optionally fluoro-containing monomers, and optionally in the presence of hydrogen-containing olefins, by polymerization in aqueous emulsion or in suspension, are known.
It is known that in the (co)polymerization in aqeuous emulsion of fluoro-containing monomers the addition of chlorofluorocarbons (CFC) increases the reaction rate. See for instance U.S. Pat. No. 3,535,926.
To avoid the use of CFC considered harmful to the ozone layer of the atmosphere, (co)polymerization processes are known in the art wherein fluoro-containing monomers are polymerized in the presence of perfluoropolyoxyalkylenes with fluoro-containing end groups utilized under the form of dispersions and/or aqueous emulsions. See for intance U.S. Pat. No. 4,789,917. These processes also allow to obtain an improvement of the reaction rate and a lowering of the working pressure.
(Co)polymerization processes are also known in the art wherein the fluoro-containing monomers are polymerized in the presence of perfluoropolyoxyalkylenes with fluoro-containing end groups utilized under the form of aqueous microemulsion, see for instance U.S. Pat. No. 4,864,006, by which it is possible to further increase the reaction rate.
(Co)polymerization processes of fluoro-containing monomers in aqueous emulsion are also known, wherein an aqueous emulsion of a perfluoropolyoxyalkylene having hydrogen-containing end groups and/or hydrogen-containing repeating units is used.
It has thus been possible to obtain the reduction of the trigger time and a minimization of the formation of low molecular weights compared with the processes employing perfluoropolyoxyalkylenes microemulsions with perfluorinated end groups. The reaction rate substantially results similar to that obtained with the perfluoropolyethers microemulsions with perfluorinated end groups. See European patent application EP-A-625,526.
The Applicant has unexpectedly and surprisingly found that it is possible to further improve the reaction rate in (co)polymerization processes of unsaturated perfluoromonomers, fluoro-containing monomers and optionally in the presence of hydrogen-containing olefins to give polymers containing hydrogen and fluorine, and in the meantime to obtain polymers with good mechanical properties and improved chemical resistance defined hereinafter.
Object of the present invention is therefore a polymerization process of unsaturated perfluoromonomers, fluoro-containing monomers, and optionally in the presence of hydrogen-containing olefins for obtaining polymers containing hydrogen and fluorine, which utilizes a microemulsion comprising the following components:
(a) water;
(b) a fluoropolyoxyalkylene having hydrogen-containing end groups and/or hydrogen-containing repeating units;
(c) a fluorine-free organic radicalic initiator for the polymerization of fluoro-containing monomers, soluble in component (b). The component c) is optionally dissolved in an hydrocarbon C
1
-C
20
, preferably C
1
-C
14
, of aliphatic, cycloaliphatic, aromatic or mixed type, optionally the hydrocarbon can contain halogen atoms, i.e. chlorine and bromine; the solution being soluble in component b);
(d) a fluoro-containing surfactant.
The fluoropolyoxyalkylenes having hydrogen-containing end groups and/or hydrogen-containing repeating units of component b), are known products, already described, for instance, in the already cited European patent application No. 625526. They are formed by repeating units, randomly distributed along the chain, selected from:
—CFZO—, —CF
2
CFZO—,
—CZ
2
CF
2
CF
2
O—,
where Z is H or F, R
f
is CF
3
, C
2
F
5
, or C
3
F
7
;
and by hydrogen-containing end groups selected from —CF
2
H, —CF
2
CF
2
H, —CFH—CF
3
, and —CFH—OR
f
, wherein R
f
is defined as above; or perfluorinated end groups selected from —CF
3
, —C
2
F
5
, and —C
3
F
7
, at least one of the end groups containing hydrogen. The perfluorinated end group can also contain a chlorine atom, for instance of the type CF
2
Cl, CF
3
—CFCl—CF
2
,
according to EP patents 340,740, 340,739.
The average molecular weight is generally from 200 to 4000, preferably from 400 to 1000. The content in hydrogen is generally higher than 10 ppm, preferably higher than 100 ppm. In practice the low value of hydrogen is obtained by a mixture of perfluoropolyethers (PFPE) containing hydrogen (H) in the end group and/or in hydrogen-containing repeating units, with PFPE not containing H. The H maximum value is obtained when component b) contains only PFPE containing H as defined above. Intermediate values are obtained by modulating the amounts of the two PFPE products containing H and not containing H.
In particular, the fluoropolyoxyalkylenes containing hydrogen can be selected from the following classes:
wherein:
T
1
and T
2
, equal to or different from each other, are hydrogen-containing groups —CF
2
H, —CFH—CF
3
, or perfluorinated groups —CF
3
, —C
2
F
5
, —C
3
F
7
, wherein at least one of the end groups contains hydrogen;
X is —F or —CF
3
; a, b being integers such that the molecular weight is comprised in the above range, a/b being comprised between 5 and 15;
(b) T
3
—O(CF
2
CF
2
O)
c
(CF
2
O)
d
—T
4
wherein:
T
3
and T
4
, equal to or different from each other, are hydrogen-containing groups —CF
2
H or —CF
2
—CF
2
H, or perfluorinated groups —CF
3
, —C
2
F
5
; wherein at least one of the end groups contains hydrogen; c, d being integers such that the molecular weight is comprised in the above range, c/d is comprised between 0.3 and 5;
wherein:
T
5
and T
6
, equal to or different from each other, are hydrogen-containing groups —CF
2
H, —CF
2
CF
2
H, or —CFH—CF
3
, or perfluorinated groups —CF
3
, —C
2
F
5
, —C
3
F
7
, wherein at least one of the end groups contains hydrogen; X is —F or —CF
3
; e, f, g are integers such that the molecular weight is comprised in the above range, e/(f+g) being comprised between 1 and 10, f/g being comprised between 1 and 10;
wherein:
T
7
and T
8
are hydrogen-containing groups —CFH—CF
3
, or perfluorinated groups —C
2
F
5
, —C
3
F
7
, at least one of the end groups containing hydrogen; h being an integer such that the molecular weight is comprised in the above range;
(e) T
9
—O(CZ
2
CF
2
CF
2
O)
i
—
T
10
wherein:
Z
2
is F or H; T
9
and T
10
, equal to or different from each other, are groups —CF
2
H or —CF
2
—CF
2
H, or perfluorinated groups —CF
3
, —C
2
F
5
, —C
3
F
7
, wherein at least one of the end groups contains hydrogen; i being an integer such that the molecular weight is comprised in the above range;
wherein:
R
f
is —CF
3
, —C
2
F
5
, or —C
3
F
7
; T
11
and T
12
, equal to or different from each other, are groups —CF
2
H, —CF
2
CF
2
H, —CFH—OR
f
, or perfluorinated groups —CF
3
, —C
2
F
5
, —C
3
F
7
, wherein at least one of the end groups contains hydrogen; j, k, l being integers such that the molecular weight is comprised in the range indicated above, k+l and j+k+l are at least equal to 2, k/(j+l) is comprised between 10
−2
and 10
3
, l/j is comprised between 10
−2
and 10
2
;
wherein:
T
13
and T
14
, equal to or different from each other, are hydrogen-containing groups —CF
2
H, —CFH—CF
3
, or perfluorinated groups —CF
3
, —C
2
F
5
, —C
3
F
7
, wherein at least one of the end groups contains hydrogen;
X is —F or —CF
3
; m, n, o, p being integers such that the molecular weight is comprised in the range indicated above, m
is comprised between 5 and 40, m/(o+p) is comprised between 2 and 50, o+p is at least 3, o is lower than p;
(h) T
15
—O(CF
2
CF
2
O)
q
(CF
2
O)
r
(CFHO)
s
(CF
2
CFHO)
t
—T
16
wherein:
T
15
and T
16
, equal to or different from each other, are hydrogen-containing groups —CF
2
H, —CF
2
—CF
2
H, or perfluorinated groups —CF
3
, —C
2
F
5
, at least one of the end groups containin

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