Peroxide-curable fluorocarbon elastomers having interpolymerized units derived from a cure site monomer containing bromine or iodine. The fluorocarbon elastomer gums are prepared by copolymerizing with the principal monomers normally used in preparing fluorocarbon elastomers, e.g. vinylidene fluoride, hexafluoropropene, and (optionally) tetrafluoroethylene, a small amount of a novel cure site monomer which is a vinyl ether in which at least one of the two vinylic (or double-bonded) carbon atoms thereof is bonded to at least one bromine or iodine atom, e.g. CF.sub.3 CH.sub.2 OCF.dbd.CFBr. The cured fluorocarbon elastomers of this invention have useful properties normally associated with fluorocarbon elastomers, such as acid resistance, thermal stability, and high tensile strength. These properties of shaped articles made from these fluorocarbon elastomers are not adversely affected upon exposure to high temperatures for extended periods.

This invention relates to fluorocarbon elastomrs and their preparation and 
use. In another aspect, it relates to peroxide-curable fluorocarbon 
elastomers having interpolymerized units derived from a cure site monomer 
containing bromine or iodine, and to the preparation of such fluorocarbon 
elastomers. 
Fluorocarbon elastomers are premium materials for demanding service 
applications in harsh environments where extremes in temperature and 
aggressive chemicals are encountered, namely, applications in the 
automotive, petroleum, and energy-related industries. It is their 
generally high temperature stability, low compression set, and chemical 
and fluid resistance which enables fluorocarbon elastomers to have a 
variety of uses, such as seals, gaskets, and linings, in these areas; see 
West, A. C. and Holcomb, A. G., "Fluorinated Elastomers", Kirk-Othmer, 
"Encyclopedia of Chemical Technology", Vol. 8, 3rd Ed., John Wiley & Sons, 
Inc., pp. 500-515 (1979). 
The commercial fluorocarbon elastomers are principally those made by 
polymerizing vinylidene fluoride with one or two other terminally 
unsaturated fluorine-containing comonomers, such as hexafluoropropene, 
1-hydropentafluoropropene, chlorotrifluoroethylene, perfluoro(methyl vinyl 
ether), and tetrafluoroethylene. Another commercial type is the copolymer 
of tetrafluoroethylene with propylene or perfluoro(methyl vinyl ether). 
The cure systems for converting the fluorocarbon elastomer gums into 
insoluble elastomers are basically of three types: diamine, 
dihydroxyaromatic, and free radical or peroxide systems. They have their 
relative merits, though the dihydroxyaromatic cure system is most widely 
used and recently the enhanced peroxide curing of fluorocarbon elastomers 
made with cure site monomers containing bromine or iodine has received 
increasing commercial attention; see Albin, L. D., Kosmala, J. L., and 
Stoskopf, A. H., "Rubber & Plastic News," pp. 28-30, Nov. 9, 1981, and 
Apotheker, D., Finlay, J. B., Krusic, P. J., and Logothetis, A. L., 
"Rubber Chemistry and Technology," 55 pp. 1004-18 (1982). 
Prior art disclosures of fluoropolymers made with bromine- or 
iodine-containing materials include U.S. Pat. No. 3,351,619 (Warnell) 
which discloses use of a vinyl ether containing a fluoroalkyl iodide 
group; U.S. Pat. No. 3,306,879 (Pattison) which discloses the use of such 
compounds as 2-bromoethyl vinyl ether and 2-iodoethyl vinyl ether; U.S. 
Pat. Nos. 4,035,565 (Apotheker et al) and 4,263,414 (West) which disclose 
the use of bromine-containing olefins, such as bromotrifluoroethylene, 
1-bromo-2,2-difluoroethylene, and vinyl bromide; U.S. Pat. Nos. 4,251,399 
(Tomoda et al), 4,243,770 (Tatemoto et al), and 4,260,698 (Tatemoto et al) 
which disclose the use of iodinated compounds such as I(CF.sub.2 
CF.sub.2).sub.2 I; and European Patent Application No. 0 079 555 (Kojima 
et al) published May 25, 1983, which discloses the use of 
perfluoro(2-bromoethyl vinyl ether). 
Briefly, in one aspect of this invention, fluorocarbon elastomer gums are 
prepared by copolymerizing with the principal monomers normally used in 
preparing fluorocarbon elastomers, e.g. vinylidene fluoride, 
hexafluoropropene, and (optionally) tetrafluoroethylene, a small amount of 
a novel cure site monomer which is a vinyl ether in which at least one of 
the two vinylic (or double-bonded) carbon atoms thereof is bonded to at 
least one bromine or iodine atom. Such bromine- or iodine-containing cure 
site monomers, e.g., CF.sub.3 CH.sub.2 OCF.dbd.CFBr, thus provide in the 
backbone of the fluoropolymer along with the principal interpolymerized 
units, e.g., --CH.sub.2 CF.sub.2 --, --CF.sub.2 CF(CF.sub.3)--, and 
--CF.sub.2 CF.sub.2 --, derived from the principal monomers, additional 
interpolymerized units, e.g., --CF(OCH.sub.2 CF.sub.3)CFBr--, containing 
bromine or iodine atoms directly bonded to catenary (or backbone) carbon 
atoms as reactive sites for reaction with organic peroxide curing agents 
which are blended with the fluorocarbon elastomer gum. The fluoropolymer 
when heated with the peroxide (and optional co-curing agents such as 
triallylisocyanurate) provides catenary cure sites between which 
crosslinking is believed to be effected and a crosslinked or cured, 
insoluble, fluoropolymer results. 
The cured fluorocarbon elastomers of this invention have useful properties 
normally associated with fluorocarbon elastomers, such as acid resistance, 
thermal stability, and high tensile strength. These properties, 
particularly the tensile strength of many of the cured fluorocarbon 
elastomers of this invention (e.g., those where vinylidene fluoride and 
hexafluoropropene are used as principal monomers), depending upon their 
particular composition and polymerization conditions used in their 
preparation, are not significantly or adversely affected upon exposure or 
shaped articles made therefrom to high temperatures for extended periods. 
A broad class of the bromine- or iodine-containing vinyl ethers used as 
cure site monomers in accordance with this invention can be expressed by 
the formula ROCX.dbd.CYZ, where one or two of the X, Y and Z substituents 
are selected from bromine and iodine atoms, and the remainder of the 
substituents are independently hydrogen, fluorine, or (less preferably) 
chlorine atoms. Preferably, the halogen substituent(s) is either bromine 
or less preferably iodine and is bonded to the terminal carbon atom of the 
vinyl group, X thus being hydrogen, fluorine, or (less preferably) 
chlorine atoms. R in said formula is either a saturated or unsaturated, 
straight or branched chain or cyclic alkyl or alkenyl radical, an aryl 
radical, or combinations of such radicals, such as an alkaryl radical, 
which radicals do not interfere with the function of the vinyl ether as a 
cure site monomer. The hydrogen atoms of R may be replaced with chlorine 
or fluorine substituents, and R may contain catenary hetero-atom such as 
nitrogen or oxygen. R is preferably an aliphatic group, e.g., with 1 to 
about 6 carbon atoms, particularly an alkyl radical which is bonded to the 
ether oxygen atom through a methylene group. 
A particularly useful class of the vinyl ether cure site monomers of this 
invention are the bromine-containing vinyl ethers of the formula 
R'OCF.dbd.CFBr, where R' is a lower alkyl or alkenyl group, having, for 
example, one or two carbon atoms, or an aryl radical such as phenyl. 
Particularly useful members of this class are CF.sub.3 CH.sub.2 
OCF.dbd.CFBr, C.sub.2 H.sub.5 OCF.dbd.CFBr, C.sub.6 H.sub.5 OCF.dbd.CFBr, 
and CH.sub.3 OCF.dbd.CFBr. 
The bromine- or iodine-containing vinyl ethers used in this invention may 
be prepared by known methods, for example, see Spears, L., Szur, A. J., 
and Terell, R. C., Jour. of Medicinal Chemistry, 15, pp. 606-608 (1972). 
The bromine-containing vinyl ethers may be prepared conveniently and in 
high yield by a two-step process. The first step is a base-catalyzed 
addition of a hydroxy-containing material of the formula ROH, where R is 
as defined above, to a bromine- or iodine-containing fluoroolefin of the 
formula CR.sup.1 R.sup.2 .dbd.CR.sup.3 Br or CR.sup.1 R.sup.2 
.dbd.CR.sup.3 I where at least one of R.sup.1, R.sup.2, and R.sup.3 is a 
fluorine atom and the remainder are independently hydrogen or halogen 
atoms. Representative bromine- and iodine-containing fluoroolefins useful 
as starting materials in the reaction include bromotrifluoroethylene, 
1-bromo-2,2-difluoroethylene, 1,1-dibromodifluoroethylene, and 
iodotrifluoroethylene. Optionally, an aprotic solvent, such as 
N,N-dimethylformamide, may be used in this reaction; for examples, see 
U.S. Pat. No. 3,666,864 (Terrell); Demiel, A., J. of Organic Chemistry, 
25, pp. 993-6, (1960 ); and Park, J. D., Cummings, H. L. and Locher, J. 
R., J. of Organic Chemistry, 23, pp. 1785-6 (1958). The second step 
consists of the treatment of the reaction product of the first step with a 
strong base such as potassium hydroxide to effect the elimination of 
hydrogen halide and yield the desired bromine- or iodine-containing vinyl 
ether (for related example, see Corley, R. S., Lal, J., and Kane, M. W., 
J. of American Chem. Soc., 78, pp. 3489-3493 (1956)). Examples of 
bromine-containing vinyl ethers which can be prepared by this method 
include CH.sub.3 OCF.dbd.CFBr and CF.sub.3 CH.sub.2 OCF.dbd.CFBr. The 
overall reaction scheme using bromotrifluoroethylene as the fluoroolefin 
is: 
##STR1## 
Other methods of preparation include the following reaction sequence: 
##STR2## 
For preparation of ROCH.dbd.CF.sub.2 see Wheaton, G. A. and Burton, D. J., 
J. of Organic Chemistry, 48, pp. 917-927 (1983). 
The amount of the cure site monomers to be copolymerized with the main 
monomers or comonomers of the fluorocarbon elastomers of this invention 
will be, functionally speaking, an amount sufficient to provide cure sites 
or reactive sites so as to obtain the desired degree or state of cure when 
the resulting fluoropolymer gum containing such cure sites is compounded 
with the peroxide curing agent and the shaped article of the formulation 
is heated to effect cure or vulcanization. Generally, sufficient cure site 
monomer will be less than about 5 mole percent and preferably in the range 
of 0.1 to 1.5 mole percent, based on the total moles of the cure site 
monomer used and the principal monomers used to form the fluorocarbon 
elastomer gum. Those amounts of cure site monomer generally will provide 
at least about 0.05 weight percent bromine or iodine in the fluoropolymer. 
Among the fluorocarbon elastomers which can be made or in a sense modified 
by incorporating a small amount of the bromine- or iodine-containing vinyl 
ether cure site monomers are the elastomeric copolymers of vinylidene 
fluoride with at least one terminally unsaturated comonomer containing at 
least one fluorine atom substituent on each vinylic or double-bonded 
carbon atom, each carbon atom of said comonomer being substituted only 
with fluorine, chlorine, hydrogen, lower fluoroalkyl radical, or lower 
fluoroalkoxy radical, particularly hexafluoropropene, tetrafluoroethylene, 
chlorotrifluoroethylene, perfluoromethyl perfluorovinyl ether, and 
1-hydropentafluoropropene. Tetrafluoroethylene may also be copolymerized 
with the cure site monomer and olefinic hydrocarbon compounds such as 
ethylene or propylene and optionally also vinylidene fluoride. Another 
class of fluorocarbon elastomers of this invention are those made by 
copolymerizing the cure site monomers with tetrafluoroethylene and a 
perfluoroalkyl perfluorovinyl ether such as perfluoromethyl perfluorovinyl 
ether. Particular fluorinated elastomers which can be modified by 
incorporating the vinyl ether cure site monomer are those produced by 
copolymerizing vinylidene fluoride with a fluorine-containing olefin and 
optionally perfluoroalkyl perfluorovinyl ether, such as the vinylidene 
fluoride/hexafluoropropene copolymer described in U.S. Pat. Nos. 3,051,677 
(Rexford) and 3,318,854 (Honn et al). Other fluorocarbon elastomers that 
can be modified are those copolymers produced by copolymerizing vinylidene 
fluoride, hexafluoropropene, and tetrafluoroethylene as described in U.S. 
Pat. No. 2,968,649 (Pailthorp et al), and those copolymers produced by 
copolymerizing tetrafluoroethylene with propylene as described in U.S. 
Pat. No. 4,277,586 (Ukihashi et al). 
In one preferred embodiment, the fluorocarbon elastomers of this invention 
are copolymers whose interpolymerized units comprise, consist, or consist 
essentially of 50 to 85 mole percent of units derived from vinylidene 
fluoride, 10 to 50 mole percent of units derived from hexafluoropropylene, 
0 to 30 mole percent of units derived from other highly fluorinated 
monomers, such as tetrafluoroethylene, and 0.15 to 1.5 mole percent of 
units derived from said bromine-containing or iodine-containing vinyl 
ether cure site monomers. Another embodiment is a copolymer with 35 to 70 
mole percent of units derived from tetrafluoroethylene, 30 to 65 mole 
percent of units derived from propene or butene, and 0.15 to 1.5 mole 
percent of units derived from the cure site monomer. 
The fluoropolymers of this invention can be prepared by known high 
pressure, free-radical polymerization techniques generally used to prepare 
fluorocarbon elastomers such as vinylidene fluoride/hexafluoropropene 
polymers, for example, those techniques described by West and Holcomb, 
supra, and in said U.S. Pat. No. 4,035,565. Briefly, the fluoropolymers 
are prepared by charging a pressure reactor with reaction diluent, pH 
buffer, emulsifier, initiator, and the cure site monomer and principal 
comonomers; carrying out the emulsion polymerization of the charge at 
constant elevated temperature, e.g. 35.degree. to 125.degree. C., and 
pressure, e.g. 0.5 to 10 MPa, with agitation; coagulating the resulting 
latex; and filtering, washing, and drying the resulting fluorocarbon 
elastomer gum. 
Though any of the conventional "free-radical" generating cure initiators 
can be used in the vulcanization or curing of the fluoropolymer gum of 
this invention, such as actinic radiation, electron beam, and organic or 
inorganic peroxides, organic peroxides are preferred. Suitable peroxides 
include benzoyl peroxide, bis(2,4 dichlorobenzoyl)peroxide, dicumyl 
peroxide, t-butylhydroperoxide, di-t-butyl peroxide, t-butylperoxy 
benzoate, and lauroyl peroxide. Particularly useful commercially available 
peroxides are 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane and 
2,5-dimethyl-2,5-bis(t-butylperoxy)hexyne-3 which are the active 
ingredients of products sold as "Luperco" 101XL and 130XL, respectively. 
The amount of peroxide curing agent to be mixed with the fluorocarbon 
elastomer gum, e.g. on a two-roll mill, in a Banbury mixer, or in a mixing 
extruder, generally will be 0.1 to 10, preferably 1 to 5, parts per 100 
parts of the fluoropolymer gum. 
Along with the peroxide curing agent it will generally be desirable to 
incorporate in or compound with the gum a cocuring agent (or coagent), 
such as are commonly used in peroxide vulcanization of fluorocarbon 
elastomers to obtain a tighter or faster cure or better compression set. 
Such cocuring agents generally will be used in amounts of 0.1 to 10, 
preferably 1 to 5, parts per 100 parts of the fluoropolymer gum. Cocuring 
agents which can be used include triallylcyanurate, diallylphthalate, 
allylmethacrylate and, particularly, triallylisocyanurate. 
In many cases, for optimum vulcanizate physical properties, such as tensile 
strength, it will be desirable to include in the compounding formulation a 
reinforcing filler such as carbon black, silica, iron oxide, or zinc 
oxide, e.g. 5 to 60 parts by weight per 100 parts by weight of the 
fluoropolymer gum. Acid acceptors, such as magnesium oxide and calcium 
hydroxide, pigments, plasticizers, and processing aids which are 
compatible with the gum can be mixed therewith. 
For some applications it may be desirable to blend or combine the 
fluorocarbon elastomer gum (containing the bromine or iodine cure sites 
derived from the vinyl ether cure site monomers) with other 
peroxide-curable elastomers, such as fluorosilicone gums (as described in 
said U.S. Pat. No. 4,263,414). The fluorocarbon elastomer gum can be first 
banded on a two-roll mill and then the other gums, if any, blended in 
until uniform, or the gums can be banded together, and the balance of 
compounding adjuvants can then be milled in as a mixture. 
In making the shaped articles, generally the compounded, vulcanizable 
mixture or fluorocarbon elastomer gumstock is extruded or molded in a 
cavity or transfer mold at a temperature in the range of 125.degree. to 
250.degree. C. for 1 to 50 minutes or more at about 5 to 10 MPa. The 
extruded or press-cured article is then transferred to a circulating air 
oven and post-cured at about 170.degree. to 260.degree. C. for about 2 to 
24 hours, preferably at about 230.degree. C. for 16 hours, yielding cured 
(that is, crosslinked or vulcanized) shaped articles which are elastomeric 
(i.e., materials which, when slowly stretched at room temperature to at 
least twice their original length and released, return rapidly to 
essentially their original length). 
The curable fluorocarbon elastomer compositions of this invention can be 
employed in making molded or extruded articles of manufacture, such as 
gaskets, O-rings, diaphragms, tubing, ducting, carburetor fuel tips, fuel 
pump cups, shaft seals, and other molded goods. The particular application 
will usually be determined by the properties of the cured polymer, the 
requirements of such applications being well known and described, for 
example, in the prior art publications described hereinbefore. 
Objects and advantages of this invention are illustrated in the following 
examples. Cure characteristics of compounded gum were measured according 
to ASTM-D2084-75 with an oscillating disc rheometer and reported as "ODR". 
The press-cured sheets, 150 mm33 150 mm.times.2 mm sheets, and O-rings, 15 
mm diameter, 3.5 mm thick, were pressed at about 7 MPa for 15 minutes at 
177.degree. C. The post-cured sheets were those removed from the press and 
placed for 16 hours in a circulating air oven having a temperature 
maintained at 232.degree. C. The accelerated aging was carried out 
according to ASTM D 573-78, the samples being exposed for the indicated 
time at the indicated temperature. Compression set was determined in 
accordance with ASTM D 395-78 (Method B) using 15 mm diameter O-rings 3.5 
mm thick compressed to 2.6 mm under the indicated conditions. Tensile 
strength, elongation at break, and modulus at 100 percent elongation were 
measured in accordance with ASTM D 412-80, using Die D. Hardness was 
measured in accordance with ASTM D 2240-75, using Durometer A and taking 
readings 2 seconds after the presser foot came into contact with the 
specimen.

EXAMPLE 1 
To a 500 ml 3-neck, magnetically stirred flask, fitted with a thermometer, 
water-cooled condenser, and a gas dispersion tube, was added 150 ml 
N,N-dimethylformamide, 119 g (1.19 mole) 2,2,2-trifluoroethanol, and 4.5 g 
(0.11 mole) sodium hydroxide and the system was purged with nitrogen. The 
system was then placed under a slight positive nitrogen pressure and 
bromotrifluoroethylene (192 g, 1.19 mole) was slowly added via the gas 
dispersion tube over a period of one hour while the stirred flask was 
cooled with an ice/water bath to maintain a temperature of 
35.degree.-40.degree. C. in the flask. After the reaction was complete, 
the reaction mixture was poured into 500 ml water. The lower layer was 
separated and washed twice with 500 ml water. The crude product was 
distilled using a 40 cm Vigreux column. The fraction distilling at 
93.degree.-94.degree. C., weighing 255 g, was collected and identified as 
CF.sub.3 CH.sub.2 OCF.sub.2 CFBrH by H- and F-NMR analyses. Purity was 
found to be 99.9% by gas-liquid chromatography. 
A 500 ml magnetically stirred 3-neck flask was fitted with a thermometer, 
addition funnel, and a distillation head attached to a water-cooled 
condenser connected to a receiving flask cooled with an ice/water bath. 
Solid 85% potassium hydroxide (549 g) was added to the flask and the 
system was purged with nitrogen. The reaction flask was then heated to 
fuse the KOH and the temperature was maintained at 140.degree. C. with 
stirring. A slow nitrogen flow was maintained through the system while the 
above-prepared CF.sub.3 CH.sub.2 OCF.sub.2 CFBrH (255 g, 0.98 mole) was 
slowly added over a 3-hour period. During this time, 222 g of a clear, 
colorless liquid was collected in the receiving flask. This material was 
analyzed by H- and F-NMR and found to correspond to "Composition A" in 
Table 1. 
By a procedure similar to that of the above paragraph, similarly prepared 
CF.sub.3 CH.sub.2 OCF.sub.2 CFBrH (69 g, 0.26 mole) and 206 g of 
"Composition A" were reacted with 677 g of 85% KOH at 
155.degree.-170.degree. C. to give 245 g of material designated as 
"Composition B" in Table 1. 
TABLE 1 
______________________________________ 
Composition (mole %) 
Compound "A" "B" 
______________________________________ 
CF.sub.3 CH.sub.2 OCF .dbd. CFBr 
71.4 79.3 
CF.sub.2 .dbd. CHOCF .dbd. CFBr 
3.1 8.3 
CF.sub.3 CH.sub.2 OCF.sub.2 CFBrH 
25.5 12.4 
______________________________________ 
EXAMPLE 2 
CH.sub.3 OCF.sub.2 CFBrH was prepared as described in U.S. Pat. No. 
3,666,864 (Terrell). By a procedure similar to that described in Example 
1, 351 g of CH.sub.3 OCF.sub.2 CFBrH (1.82 mole) was reacted with 649 g of 
85% KOH at 175.degree. C. to give 277 g of a material designated 
"Composition C" in Table 2. 
By a procedure similar to that described in Example 1, 269 g of 
"Composition C" was reacted with 700 g of 85% KOH at 200.degree. C. to 
give 231 g of a material designated "Composition D" in Table 2. 
By a procedure similar to that described in Example 1, 1345 g CH.sub.3 
OCF.sub.2 CFBrH was reacted with 2290 g of 91% KOH at 170.degree. C. to 
give 1030 g of a clear, colorless liquid. This reaction was repeated three 
times on a similar scale and the reaction products of the four runs were 
combined. The combined product mixture was distilled using a 40 cm Vigreux 
column and 3907 g of a fraction having a boiling range of 
69.degree.-84.degree. C. was collected and is designated "E" in Table 2. 
TABLE 2 
______________________________________ 
Composition (mole %) 
Compound "C" "D" "E" 
______________________________________ 
CH.sub.3 OCF=CFBr 
55.9 85.7 82.4 
CH.sub.3 OCF.sub.2 CFBRH 
44.1 14.3 17.6 
______________________________________ 
EXAMPLE 3 
Two fluoroelastomers of the present invention were prepared by the 
following general procedure, with specific charges and reaction conditions 
being listed in Table 3. 
A stirred reactor was charged and the reaction mixture was polymerized 
under pressure at elevated temperature and with agitation. A portion of 
the resulting latex was coagulated by adding dropwise to a stirred aqueous 
solution containing MgCl.sub.2 and 1-butanol, with a typical coagulation 
recipe as follows: 
______________________________________ 
Parts by weight 
______________________________________ 
latex 2500 
magnesium chloride 
12 
1-butanol 25 
deionized water 830 
______________________________________ 
After coagulation was complete, the raw gum was washed 5 times with hot 
deionized water (about 60.degree. C.). Excess water was removed and the 
raw gum was dried overnight at about 105.degree. C. 
The raw gum was compounded on a two-roll water-cooled mill by adding a 
mixture of the compounding ingredients to the banded fluorocarbon 
elastomer gum. The compounding recipe was as follows: 
______________________________________ 
Parts by weight 
______________________________________ 
fluoroelastomer gum 100 
medium thermal carbon black (N-990) 
30 
calcium hydroxide 3 
"Luperco" 101XL* 2.5 
triallylisocyanurate 2.5 
______________________________________ 
*45% 2,5dimethyl-2,5-bis(t-butylperoxy)hexane on an inert filler 
Press cured sheets and O-rings were prepared and post-cured. Their 
properties are listed in Table 4. 
TABLE 3 
______________________________________ 
Fluoroelastomer Preparation 
Runs 
1 2 
______________________________________ 
Cure site monomer composition 
"B" "D" 
Monomer blend, wt. % 
vinylidene fluoride 59.87 59.86 
hexafluoropropene 39.41 39.31 
cure site monomer 0.72 0.83 
Charge, parts by weight 
deionized water 3000 3000 
K.sub.2 HPO.sub.4 12.6 13.1 
K.sub.2 S.sub.2 O.sub.8 
2.64 7.0 
C.sub.8 F.sub.17 SO.sub.2 N(C.sub.2 H.sub.5)CH.sub.2 CO.sub.2 K 
0 0.6 
C.sub.7 F.sub.15 CO.sub.2 H 
12.6 0 
hexafluoropropene precharge 
25 25 
monomer blend 1150 1150 
Reactor stirrer speed, rpm 
750 750 
Reaction temperature, .degree.C. 
68 68 
Reaction pressure, MPa 
1.3 1.3 
Reaction time, hours 22 14 
Mooney viscosity, 93 53 
ML 1 + 10 @ 121.degree. C. 
Gum analysis, wt. % 
C 31.6 31.1 
H 1.7 1.7 
Br 0.22 0.26 
Gum composition, mole % 
vinylidene fluoride 75.37 72.37 
hexafluoropropene 24.39 27.35 
cure site monomer 0.24 0.28 
______________________________________ 
TABLE 4 
______________________________________ 
Cure and Physical Properties of Compounded 
Fluoroelastomer 
Runs 
1 2 
______________________________________ 
ODR, 3.degree. arc. 100 cpm, 177.degree. C. 
minimum torque, N .multidot. m 
2.5 1.4 
time to 0.1 N .multidot. m rise, min. 
3.5 2.8 
time to 3.4 N .multidot. m torque, min. 
3.9 4.4 
time to 5.7 N .multidot. m torque, min. 
7.0 7.7 
maximum torque at 12 min., N .multidot. m 
6.6 6.1 
Press cure properties 
tensile strength, MPa 9.2 10.7 
elongation at break, % 385 307 
100% Modulus, MPa 2.2 2.5 
hardness, Shore A 63 65 
Post cure properties 
tensile strength, MPa 13.4 15.6 
elongation at break, % 272 166 
100% Modulus, MPa 3.0 3.3 
hardness, Shore A 66 67 
Heat aged properties, 70 hours @ 275.degree. C. 
tensile strength, MPa 7.3 7.2 
elongation at break, % 290 236 
100% Modulus, MPa 2.1 2.5 
hardness, Shore A 63 66 
Compression set, 
70 hrs. @ 200.degree. C., % 
41 36 
______________________________________ 
As the data of Tables 3 and 4 show, the cured fluorocarbon elastomers of 
this invention had useful press cure and post cure properties. Those 
properties were retained after heat aging, making such fluoropolymers 
useful in applications where the effects of elevated temperatures are 
important, e.g., O-ring applications. In a comparison run, using CF.sub.2 
.dbd.CFOCF.sub.2 CF.sub.2 Br as a cure site monomer, though useful press 
cure and post cure properties were obtained, they were not retained well 
after heat aging. 
EXAMPLE 4 
Another fluorocarbon elastomer, particularly useful in such applications as 
shaft seals, of this invention was prepared, compounded, and tested, using 
the procedure of Example 3 but employing different principal monomers. 
This work is summarized in Tables 5 and 6. 
TABLE 5 
______________________________________ 
Fluoroelastomer Preparation 
Cure site monomer composition 
"E" 
______________________________________ 
Monomer blend, wt. % 
vinylidene fluoride 32.68 
hexafluoropropene 43.00 
tetrafluoroethylene 23.65 
cure site monomer 0.67 
Charge, parts by weight 
deionized water 3410 
K.sub.2 HPO.sub.4 14.2 
K.sub.2 S.sub.2 O.sub.8 
7.5 
C.sub.8 F.sub.17 SO.sub.2 N(C.sub.2 H.sub.5)CH.sub.2 CO.sub.2 K 
3 
hexafluoropropene precharge 
18 
monomer blend 1340 
Reactor stirrer speed, rpm 
150 
Reaction temperature, .degree.C. 
71 
Reaction pressure, MPa 1.0 
Reaction time, hours 8.5 
Mooney viscosity, ML 1 + 10 @ 121.degree. C. 
75 
Gum analysis, wt. % 
C 28.5 
H 0.9 
Br 0.23 
Gum Composition, mole % 
vinylidene fluoride 49.98 
hexafluoropropene 26.84 
tetrafluoroethylene 22.90 
cure site monomer 0.28 
______________________________________ 
TABLE 6 
______________________________________ 
Cure and Physical Properties of Compounded 
Fluoroelastomer 
ODR, 3.degree. arc. 100 cpm, 17.degree. C. 
minimum torque, N .multidot. m 
2.5 
time to 0.1 N .multidot. m rise, min. 
3.3 
time to 3.4 N .multidot. m torque, min. 
4.2 
time to 5.6 N .multidot. m torque, min. 
10.0 
maximum torque at 12 min., N .multidot. m 
5.8 
Press cure properties 
tensile strength, MPa 7.4 
elongation at break, % 
357 
100% Modulus, MPa 2.4 
hardness, Shore A 66 
Post cure properties 
tensile strength, MPa 13.0 
elongation at break, % 
354 
100% Modulus, MPa 2.8 
hardness, Shore A 69 
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Various modifications and alterations of this invention will become 
apparent to those skilled in the art without departing from the scope and 
spirit of this invention.