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Патент USA US3051685

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Aug- 28, 1962
Filed April 29. 1957
lilnited dtates
Patented Aug. 28, 1962
ried out employing substantially the same amounts of the
monomers desired in the ?nal copolymer.
The polymerization is preferably carried out at tem
peratures of about 80° C. to 120° C., where the reaction
is rapid. At temperatures below 80° C. a very low rate
of conversion results. The process may be carried out
Dean R. Rexford, Wilmington, DeL, assignor to E. I. du
Pont de Nemours and Company, Wilmington, Del., a
corporation of Delaware
at temperatures above 120° C., but at such temperatures
Filed Apr. 29, 1957, Ser. No. 655,856
11 Claims. (Cl. 260-296)
the process is less economical.
The polymerization is preferably carried out in a stain
less steel pressure reactor or other type of equipment
which will not be reacted upon during the process, such
as an enamel-lined pressure vessel, etc. In the batch
process the vessel is ?ushed free from oxygen with a gas
This invention relates to new chemical compounds,
and more particularly to elastomeric copolymers of vinyl
idene ?uoride and hexa?uoropropene, and a preferred
process for preparing the same.
This application is a continuation-in-part of my co
and now abandoned, which in turn is a continuation-in
such as nitrogen, then it is charged with deoxygenated
water and the polymerization initiator. After closing
and evacuating the vessel, it is then charged with the
part of my application Serial No. 504,351, ?led April 27,
gaseous reactants and heated to a reaction temperature
1955 and now abandoned.
of from 80° to 120° C. under agitation. When the re
action is completed, the mass is cooled to room tempera
ture and any unreacted gas removed. The partially co
pending application Serial No. 576,519, ?led April 6, 1956,
It is known that “Te?on” polytetra?uoroethylene, which
is a polymer of tetrailuoroethylene, shows good stability "
and exceptional resistance to attack by chemical agents.
This product, however, is not considered as an elastomer,
agulated copolymer is then completely coagulated with
acids or salts in the customary manner, and is discharged
from the reactor.
since it does not have characteristic elastomeric proper
ties. Other ?uorine-containing polymeric compounds,
The copolymers of the present invention are preferably
such as the copolymers of tetra?uoroethylene and hexa 25 prepared by a continuous process wherein the monomers
are continuously fed into the reaction vessel in the pro
?uoropropene, have been disclosed, but, again, these prod
portion desired in the ultimate copolymer, the reaction
nets are not considered to he elastomers, tending more
being carried out under constant conditions such as pres
to be hard, brittle resins.
More recently there has been disclosed in “Rubber Age,’
sure, temperature, rate of conversion, and constant ratio
of catalyst to total monomers fed. 'In the accompanying
vol. 76 (January 1955), on pages 543-550, a new co
polymer of vinylidene ?uoride and chlorotri?uoroethylene
drawing which forms a part of the present speci?cation,
a schematic representation of how the continuous process
which has elastomeric properties and can be compounded
may be carried out is given.
and cured to produce a relatively thermal stable prod
As illustrated in the drawing, hexa?uoropropene is me
uct which has good chemical resistance. This product,
however, has a thermal stability of only up to around 35 tered from cylinder 1 and vinylidene ?uoride is metered
from cylinder 2 into line 3, and the mixture passes into
400° F., and even when the product is held at this tem
compressor 4 where it is pumped into reaction vessel 5.
perature for any length of time it loses its tensile strength
Simultaneously, a solution of the polymerization initiator
and becomes or’ little value.
It is an object of the present invention to produce a 40 and dispersant in tank 6 is pumped by pump 7 into re
action vessel ‘5. The reaction vessel 5 is preferably ?lled
new and improved elastomer which has excellent thermal
completely with liquid. Cylinder 8 contains nitrogen or
stability at temperatures exceeding 400° F. and Which
other inert gas and this gas applies pressure to a pressure
also exhibits excellent resistance to chemical attack. It
control valve 9. When the internal pressure in reaction
is a further object of the invention to provide an elastomer
which has good thermal stability and shows good resist 45 vessel 5 exceeds the applied pressure on valve 9, valve
9 functions to permit the copolymer emulsion to escape
ance to chemical attack which can be worked on conven
irom the reaction vessel into receiver 10 from which the
tional rubber equipment and which can be readily and
latex is removed and coagulated for further processing.
economically manufactured. It is a still further object
In carrying out the process, it is necessary to have pres
of the invention to provide a process for preparing ho
mogeneous copolymers of vinylidene ?uoride and hexa 50 ent a polymerization initiator. A well known class of
polymerization initiators which may be used are those
?uoropropene having highly desirable properties.
containing the peroxy linkage, as for example, the acyl
The copolymers of the present invention are prepared
peroxides, e.g. dibenzoyl peroxide, benzoylacetyl perox
by a process which results in elastomeric compositions
containing from 70% to 30% by weight of vinylidene
ide, diacetyl peroxide; the dialkyl peroxides, as for ex
?uoride ‘units and from 30% to 70% by weight of hexa 55 ample diethyl peroxide and ditertiary butyl peroxide; hy
drogen peroxide; salts of true non-metallic peracids as,
?uoropropene units. When the copolymer contains less
for example, ammonium persulfate,, potassium persulfate
than 30% of hexa?uoropropene units it tends to become
and sodium persulfate. The preferred initiator is a salt
non-elastic. When the polymerization of the two mono
of a peracid; ammonium persulfate being most preferred
mers is carried out by the batch process, an excess of
because of its low cost. The preferred amount of ini
the hexa?uoropropene is employed over that present in 60 tiator used is normally not less than about 0.001% but
the resulting polymer, so that ordinarily in the batch proc
generally not more than about 5% based on the total
ess from 60 to 15 parts by weight of vinylidene ?uoride
weight of the monomers. Preferably a quantity of initi
will be copolymerized with from 40 to 85 parts by weight
ator between 0.001% and 2% is preferred. Catalyst
of hexa?uoropropene to give products containing from
30% to 70% copolymerized hexalluoropropene. Since
hexa?uoropropene does not homopolymerize under the
65 activators such as sodium bisul?te and butters such as
sodium phosphate may also be used in the polymerization
conditions described herein, the use of amounts of hexa
If it is desired to obtain the elastomer in the form of
?uoropropene in excess of 85% by weight in a batch proc
a latex, a dispersant may be incorporated into the aque
ess does not produce copolymers containing more than 70 ous solution to form a homogeneous latex of the polymer,
70% by weight of copolymerized hexa?uoropropene. In . which can be readily pumped from‘ the vessel for further
the continuous process, the copolymerization will be car
processing. The dispersant should preferably be a salt of
product will not have uniform properties due to varia
tions in molecular weight. Expressed another Way, the
polymer will be heterogeneous in contrast to the homo
geneous polymer that is desired. It is essential that the
a ?uoro acid such as the ammonium salt of omega-hydro
per?uoroheptanoic acid or ammonium per?uoroocta
noate, or other types of dispersing agents which do not
readily react with ?uorine-containing compounds such as
“Chlorendic Acid,” a hexachloroendomethylenetetrahy
ratio of catalyst :to the total monomers in the feed be kept
constant; i.e., after a catalyst concentration within the
drophthalic acid. Usually it is desired to use a small
amount of the ammonium salt of the ?uoro acid even
above limits is selected and a selection of monomer ratio
to each other is made, these ratios must remain constant
or again the homogeneity of the polymer will be affected
when other dispersing agents are employed. The dispers
ing agents should be employed in from about 0.01% to
and the physical properties of the copolymer will be im
about 0.2% of the weight of the water used in the re
action. After coagulating, ?ltering and washing with
water, the product is dried and is ready for subsequent
It is preferred to carry out the process with the reactor
compounding and curing.
entirely ?lled with the emulsion, since varying levels
actant mixture comprising about 60% by weight vinyli
dene ?uoride and about 40% by weight hexa?uoropro
pene, the elastomeric copolymer will contain approxi
mately 70% by weight of vinylidene ?uoride and 30%
by weight of hexa?uoropropene. On the other hand,
aid in yielding a copolymer of uniform properties. A
,(or volumes) of liquid in the reactor will cause the end
In the batch process a conversion of up to about 90%
of the monomers to the copolymer is obtained. When 15 product to vary. By using a constantlevel reactor, how
ever, constant conditions are readily maintained which
the reaction is carried out batch-wise with a gaseous re
dispersant is used to ensure a uniform emulsion in the re
action vessel.
‘Ihe elastomeric copolymers obtained from the reac
tion of this invention are elastomeric in nature, but can
be further treated to produce elastomers of exceptionally
when the gaseous reactant mixture is approximately 85%
good physical and chemical properties. This subsequent
of hexafluoropropene and 15% of vinylidene ?uoride,
treatment is a curing process which probably causes
then the elastomeric copolymer obtained will contain
about 70% by Weight of hexa?uoropropene units and 25 cross-links to be established throughout the copolymer.
Curing and compounding of polymers is well known in
about 30% by weight of vinylidene ?uoride units. It is
the art and can conventionally be carried out by the usual
of course to be understood that copolymers having inter
methods for this type of polymer. Particularly useful in
mediate amounts of the reactant units can be obtained by
curing the copolymers of this invention are the peroxides,
the batch process by Varying the ratios of gaseous re
speci?cally benzoyl peroxide, or polyamines such as
actants within the range indicated above.
In the continuous process, it is necessary to control the
following features:
triet‘nylene tetramine, hexamethylene diamine, hexa
methylene tetramine, hexamethylenediaminecarbamate,
_ 1,3 -diaminocyclohexane, bis ( 4-aminocyclohexyl) methane,
and the like. Also useful is a cure obtained with ionizing
The hexa?uoropropene and vinylidene ?uoride must 35 irradiation, either beta or gamma rays, as obtained from
be fed into the reactor so that the composition of their
high intensity cobalt-60 or by high energy electrons ob~
mixture is a value ranging from 30 to 70 weight percent
tained from a Van der Graaf accelerator. When using
of hexa?uoropropene monomer and 70 to 30 weight per
peroxides, improved results are obtained by adding free
cent of vinylidene ?uoride monomer. In addition to this
radical acceptors such as N,N’-m-phenylene—bis-malein1ide
concentration range, it is_ necessary to maintain a con
stant ratio of the monomers to each other at the con
40 or methylene-bis-acrylamide.
These materials are also
useful in combination with high energy radiation. After
centration chosen. That is, having once selected a mix
curing either by peroxide compounding and heat treat
ture of monomers, for example, 40% hexafluoropropene
and 60% vinylidene ?uoride, that mixture must be main
ment or by irradiation or other method, an elastomer is
' tained in that ratio to obtain a polymer with consistent
' and halogenated hydrocarbon solvents, which is resistant
to concentrated nitric and sulfuric acids and is stable
properties. If the ratio is changed during the continuous
process, the product polymer will have physical proper
ties somewhat different from those obtained when a dif
ferent ratio is used.
The pressure at which the reaction is_carried out will
normally be selected from about 250 to 1500 p.s.i.g. and
the temperature of the reaction will be from about 80°
C. to 120° C. Temperatures and pressures below these
ranges are impractical because of extremely low rateof
polymerization. Higher temperatures and pressures are
obtained which is insoluble in ketonic, ester, hydrocarbon
at temperatures above 400° F. A particularly satisfactory
cure can be obtained by a combination of irradiation as
above mentioned, followed by a heat treatment as more
particularly exempli?ed hereinafter.
The elastomeric copolymer of this invention can be
used in the manufacture of ?lms, foils, tapes, ?bers and
articles of any desired shape, and can be used as coatings
for wires, fabrics, ceramics, etc., and for the impregnation
En or of felt which may be made from various ?bers since the
products can be extruded and molded under pressure.
Ordinarily these copolymers are preferably extruded at
temperatures not substantially higher than 190° F., al
though this temperature will vary depending upon the par
In the process of this invention it is necessary to ‘main 60 ticular constitution of the copolymer.
The following examples are given to illustrate the
tain the polymerization so that‘the monomers will be
methods of carrying out the preparation of these
converted to products at a constant conversion. If this
new copolymers. The parts used, unless otherwise desig
constant conversion is not maintained, the polymer ob
nated, are by weight.
tained will vary in properties. This constant conversion
’ considered economically undesirable.
.is easily obtained byrmaintaining the polymerization'sys
tern at equilibrium'during the process. Usually equilib
Example 1
A conditioned stainless steel pressure vessel is swept
rium conditions are obtained in. conventional plant
with nitrogen and charged with 125 parts of deoxygen
equipment in a short period of time.
ated distilled water containing 0.16 part of ammonium
7 persulfate, 0.03 part of sodium bisul?te and 0.33 part
of disodium phosphate heptahydrate. The closed vessel
The amount of the polymerization initiator will nor
‘is cooled to -—80° C. and purged of oxygen by three
mally be between 0.001% and 2% on the weight of the
alternate cycles of producing a vacuum in the vessel and
monomers, and when a concentration is chosen that con
then pressunng with oxygen-free nitrogen. The nitrogen
centration must be maintained constant during the oper
ation of the process. Unless this is done, the elastomeric 75 is then removed, and, while the system is under reduced
pressure, 35 parts each of gaseous hexa?uoropropene and
The stock is cured at 120° C. for one hour and baked
at from 120° to 150° C. for 16 hours. The vinylidene
vinylidene ?uoride is bled into the pressure vessel. The
system is agitated and the temperature inside the reaction
?uoridehexa?uoropropene elastomer thus obtained shows
good tensile strength, as exempli?ed in the following
chamber raised to 100° C. over a 15 minute period. The
autogenous pressure is observed to increase to about 700
p.s.i.g., which drops to 300 p.s.i.g. after two hours. After
an additional heating period of 12 hours to ensure that
‘the reaction is completed, the reaction mass is allowed
to cool to room temperature and the pressure chamber
Temperature of Water
vented to the atmosphere. The partially coagulated latex 10
product is removed and coagulation completed by the
addition of a small amount of dilute hydrochloric acid.
The coagulated crumb is washed thoroughly with water
25° C
Tensile at break, p.s.i.______
Elongation at break, percent
Modulus—300% p.s.i _____ __
70° 0.
100° C .
1, 850
1, 050
Example 6
The copolymer obtained in Example 1, subjected to
and rolled on a hot rubber mill at about 140° C. to ob
tain 63 parts (90% conversion) of an off-white elastomer 15
the action of 107 roentgens obtained as mono-energetic
in rolled sheet form. Analysis of this elastomer for car
electrons of 2 mev. from a Van der Graaf accelerator,
bon, hydrogen and ?uorine by combustion analysis indi
is converted to a tough elastomer which closely resembles
cates that the product copolymer contains about 45%
hexa?uoropropene and about 55% vinylidene ?uoride by
the product obtained by heat curing stock compounded
with benzoyl peroxide.
Example 2
' Example 7
Example 1 is repeated, but the pressure vessel charged
The cured copolymer of Example 5 was subjected at
with 30 parts of hexa?uoropropene and 40 parts of vinyli
dene ?uoride. The elastomer obtained is similar to, but 25 25° C. by immersion to the action of n-hexane, carbon
tetrachloride, cyclohexane, carbon ‘disul?de and formic
somewhat harder than, the product of Example 1. Com
acid. Little or no swelling action was observed after
bustion analysis indicates that this copolymer contains
16 hours’ immersion in any of these solvents. Immersion
about 30% hexa?uoropropene and about 70% vinylidene
in boiling water for 24 hours caused no swelling of the
?uoride by weight.
Example 3
30 copolymer, nor did immersion for 24 hours in 70%
HNO3 at room temperature.
When 0.01 part of the ammonium salt of omega-hydro
per?uor'oheptanoic acid is added to the reaction kettle
charge of Example 1, the product obtained after reaction
is entirely dispersed throughout the aqueous system. The
When the copolymer is subjected to low temperatures,
it retains its elastomeric properties even at 0° C. and
stiifens only slightly at -—5 ° C.
product is coagulated by the addition of sodium chloride, 35
Example 8
?ltered, washed and dried on a rubber mill. A product
To a conditioned stainless steel polymerization vessel
is added a solution of 1.04 parts of ammonium persulfate,
substantially identical to that of Example 1 is obtained.
Example 4
The elastomer of Example 1 is compounded at 25° C.
on a rubber mill to contain the following ingredients:
Then 200 parts of a mixture of 85% by weight hexa
?uoropropylene and 15% by weight vinylidene ?uoride
are introduced into ‘the vessel.
Benzoyl peroxide ___________________________ __
Zinc oxide
0.2 part of sodium bisul?te, 2.1 parts of disodiumhydro
gen phosphate .heptahydrate and 0.5 part of ammonium
per?uorooctanoate in 160 parts of deoxygenated water.
The mixture is heated
with agitation to 100° C., the pressure falling ‘from 900
p.s.i. to 550 p.s.i. in 45 minutes, at which point the re
action is complete. The latex produced in this manner
is coagulated with sodium chloride and the coagulant
The compounded stock is cured by pressing in a mold
washed and dried to yield 58 parts of polymer. Ele-.
for one hour at 120° to 150° C. and baked for an addi 50 mental analysis showed the composition of the polymer
tional 16 hours at 100° to 150° C. The resulting vinyl
to be approximately 69% by weight hexa?uoropropylene
idene ?uoride-hexa?uoropropene elastomer thus obtained
and 31% by weight vinylidene ?uoride. It is a white,
is extremely tough and has the following physical prop
tough elastomeric material.
Dibasic lead phosphite ______________________ __
Example 9
Properties at 170° F.
Tensile at break, p.s.i _____________ __
After 72
17 710
1, 490
Elongation at break, percent ______ __
Modulus-300% elongation, p.s.i__
Hardness (Shore A) _____________________________ __
Permanent Set (ASTMD—412—51’1‘ (11)), percent.-.
The elastomer obtained in Example 8 is compounded
hrs. at
400° F.
on a rubber mill at about 40° C. to contain the following
ingredients :
________ _
_______________________________ __
Zinc oxide
_______________________________ __
“Hi-Sil” 202 silica (see Ex. 5) _______________ __ 17.5
LM-3 silicone oil1 ______________________ __v__
Example 5
1LM-3 silicone oil is a low molecular weight silicone oil.
The copolymer of Example 1 is compounded at 25° C.
on a rubber millto contain:
The compounded stock is press-molded at about 120°
C. for 10 minutes. The specimen is then subjected to
beta-radiation (a dose of about 7X 106 rep.). It is then
___ 100 70
Benzoyl peroxide __________________________ __
Zinc oxide
Precipitated silica1 _________________________ __
heated in an oven at 200° C. for between 12 and 24 hours
to give an elastomer stable to storage and further heating.
Example 10
1Available as “Hi-Sil” 202 from Columbia-Southern Chemi
cal Corp.
The elastomer of Example 8 is compounded on a rub
cal properties illustrate the very desirable properties of
ber mill at about 40° C. to contain the following in
the elastomer made by the continuous process:
Yerzley resilience (25° C.) __________ __percent__
Permanent set at break _________________ __do__
“Hi-Sil” 200 silica (see Ex. 5) _______________ __ 17.5
_LM-3 silicone oil1 ________________________ __
Zinc oxide
Tensile strength ______________________ __p.s.i__ 2500
_______________________________ -_
Elongation at break _________ __'_____ __percent__
TR 10 1
'Dibasic lead phosphite _____________________ __
Brittle point _________________________ __° C__ —43
Triethylene tetrarnine ______________________ __
lTR-lt) values. are obtained according to AS’I‘M designa
tion D—1329-54T.
________________ _'______' ____________ __
° C__. -—18
Example 14
1LM—3 silicone oil is a low moleeulai' weight silicone oil.
The elastomer as obtained in Example 11 is com
pounded on a rubber mill at 25° to 50° C. to contain the
The compounded stock is molded at 150° C. to 200° C.
for from 60 to 120 minutes and then after-cured at 200°
C. for from 12 to 24 hours. A tough, snappy elastomer
following ingredients:
is obtained having the thermal properties of that de
scribed in Example 5.
Zinc oxide Dibasic lead phosphite _______________________ __
“Hi-Sil” 202 silica __________________________ __
Example 11
Employing equipment such as illustrated in the ac
companying drawing, hexa?uoropropylene is passed at a
rate of 2 pounds per hour and vinylidene ?uoride at 3
LM—3 silicone oil
Hexamethylenediamine carbamate _____________ __
The compounded polymer is press-cured for 30 minutes
pounds per hour into a one gallon stainless steel re
actor 5, which is maintained at 100° C. and operated at 25 at 275° F . and then oven cured as follows:
‘’ F.
900 p.s.i. pressure. Simultaneously, an initiator-dispersant
1 hour ______________________________ __.______ 212
1 hour ____________________________________ __ 250
solution made up of:
1 hour
30 1 hour __
13 5 parts of ammonium persulfate
27 parts of sodium bisul?te
24 hours
284 parts of disodium hydrogen phosphate
30 parts of ammonium per?uorooctanoate
21,000 parts of deoxygenated water
The cured polymer has the following properties:
Percent Retention of
is pumped at a rate of 1.06 gallons per hour into the 35
Properties alter aging
reaction vessel. The vessel is agitated continuously. The
operating pressure of 900 p.s.i. is maintained by ad
at 450° F.
justing the back pressure on valve 9 to 900 p.s.i. with
nitrogen from cylinder 8. A steady stream of latex is
produced in receiver 10. The latex is coagulated by 40
Modulus—100% elongation, p.s.i______
addition of sodium chloride, the isolated. copolymer
Tensile at break, p.s.i _______________ __
washed and dried. Analysis shows the polymer composi
Elongation at break, percent _ _ _ _
. _ __
Shore Hardness (A) ________________ __
tion by weight to be 40% hexa?uoropropylene and 60%
vinylidene ?uoride.
Example 12
Hexa?uoropropylene _______ __pounds per hour__
Vinylidene ?uoride __________________ __do____
Temperature _________________________ __° C__
The polymer is obtained ‘at a conversion of over 95% and
is isolated by coagulating latex with sodium chloride.
Analysis shows composition to be 60% by weight hexa
?uoropropylene—40% by weight vinylidene ?uoride.
.tained. As pointed out above, other curing agents may
of course be substituted for that speci?cally used in the
The elastomers of the present invention may be com
pounded in the usual manner employed in the compound
ing of elastomers generally, where additives are general
ly incorporated on the standard rubber processing equip
ment. Fillers, softening agents, reenforcing agents such as
furnace blacks, and silicas of various types including
“Estersils” (esteri?ed silica) may be incorporated therein.
1. An elastic copolymer of about 70% to 30% by
Weight of vinylidene ?uoride and from about 30% to 70%
The elastomer obtained in Example 11 is compounded
on a rubber mill at from 25° to 50° C. to contain the
following ingredients:
____ 17.5
I LM-3 silicone oil __________________________ __
Benzoyl peroxide
50 stantially the same good elastomeric properties are ob
I claim:
Example 3
The same polymer, when aged at 550° F. for as long as
72 hours, has substantially the same elastic properties.
When MT carbon black is substituted in the above
Catalyst-emulsi?er solution ____*gallons per hour__ 1.06
2, 200
28 days
. example for the silica and silicone oil combination, sub
ing conditions are used:
14 days
Following the details of Example 11, and using the
same initiator-‘dispersant solution, the following operat
Zinc oxide
The compounded polymer is pressed into slabs and
' cured at 300° F. for 45 minutes. The following mechani
by weight of hexa?uoropropene.
2. An elastic copolymer consisting of 60% by weight
of vinylidene ?uoride and 40% by Weight of hexa?uoro
3. A process for preparing an elastic polymer which
comprises reacting from 60 to 15 parts by weight of
vinylidene ?uoride with from 40 to 85 parts by weight
of hexa?uoropropene at temperatures of from 80° to 120°
C. under autogenous pressure and in the presence of a
polymerization initiator.
4. A process forpreparing an elastic polymer which
75 comprises reacting from 60 to 15 parts by weight of
vinylidene ?uoride with from 40 to 85 parts by weight of
hexa?uoropropene at temperatures of from 80° to 120° C.
under autogenous pressure and in the presence of a salt
of a true non-metallic peracid as a polymerization initi
5. A continuous process for preparing an elastic co
polymer of vinylidene?uoride and hexa?uoropropene,
which comprises feeding the monomers at a constant ratio
ing essentially of hexa?uoropropene and vinylidene?u
oride in copolymerized form and in which the hexa
?uoropropene is present in an amount of about 15 mol
9. A novel amorphous elastomeric copolymer consist
ing essentially of hexa?uoropropene and vinylidene
?uoride in copolymerized form and in which the hexa
?uoropropene is present in an amount of about 30 mol
between 70:30 and 30:70 by weight into a constant
volume of aqueous initiator dispersant solution while 10
10. A process which comprises copolymerizing a mono
maintaining a constant temperature of the solution at from
mer feed mixture consisting essentially of hexa?uoro
80° to 120° C. and a constant pressure of from 250 to
propene and vinylidene?uoride in Which the hexa?uoro
1500 pounds per square inch ‘gauge, while maintaining a
propene is present in the monomer feed mixture in an
constant ratio of the initiator present in the solution to the
amount between about 23 and about 39 mol percent at a
total monomers fed.
temperature of between about 80° C. and about 120° C.
6. A novel amorphous elastomeric copolymer consist
in the presence of a free radical-forming polymerization
ing essentially of hexa?uoropropene and vinylidene
promoter to produce a copolymer consisting essentially of
?uoride in copolymerized form and in which the hexa
hexa?uoropropene and vinylidene?uoride.
?uoropropene is present in an amount between about 15
11. An aqueous latex of a copolymer of claim 1.
and about 49 mol percent.
References Cited in the ?le of this patent
7. A novel amorphous elastomeric copolymer consist
in g essentially of hexa?uoropropene and vinylidene?uoride
in copolymerized form and in which the hexa?uoropro
Leendert ______ _; ______ .._ Apr. 5, 1951
pene is present in amount between about 15 and about 30
Sauer ________________ __ Apr. 24, 1951
mol percent.
25 2,689,241
Dittman _____________ __ Sept. 14, 1954
8. A novel amorphous elastomeric copolymer consist
Dittman et a1 ___________ __ Apr. 5, 1955
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