U.S. patent number RE32,199 [Application Number 06/706,313] was granted by the patent office on 1986-07-08 for tough, stable tetrafluoroethylene-fluoroalkyl perfluorovinyl ether copolymers.
This patent grant is currently assigned to E. I. Du Pont de Nemours and Company. Invention is credited to Dana P. Carlson.
United States Patent |
RE32,199 |
Carlson |
July 8, 1986 |
Tough, stable tetrafluoroethylene-fluoroalkyl perfluorovinyl ether
copolymers
Abstract
Tough, stable copolymers of tetrafluoroethylene monomer and
fluorovinyl ether monomers can be produced by polymerizing the
monomers in perfluorinated or suitable non-perfluorinated hydrogen
and chlorine containing fluorocarbon solvents by a process that
requires that the reaction be carried out at from about 30.degree.
to about 75.degree. C. in the presence of a low temperature
initiator such as bis(perfluoro propionyl) peroxide and a hydrogen
containing chain transfer agent such as methanol.
Inventors: |
Carlson; Dana P. (Chadds Ford,
PA) |
Assignee: |
E. I. Du Pont de Nemours and
Company (Wilmington, DE)
|
Family
ID: |
27107656 |
Appl.
No.: |
06/706,313 |
Filed: |
February 27, 1985 |
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
Reissue of: |
818391 |
Apr 22, 1969 |
03642742 |
Feb 15, 1972 |
|
|
Current U.S.
Class: |
526/206; 526/231;
526/247 |
Current CPC
Class: |
C08F
214/262 (20130101); C08F 16/24 (20130101) |
Current International
Class: |
C08F
16/24 (20060101); C08F 16/00 (20060101); C08F
214/26 (20060101); C08F 214/00 (20060101); C08F
214/26 () |
Field of
Search: |
;526/247 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Michl; Paul R.
Claims
I claim:
1. A process for forming a polymer of tetrafluoroethylene monomer
and at least one fluorovinylether monomer copolymerizable therewith
which comprises polymerizing tetrafluoroethylene with fluorovinyl
ethers selected from the group consisting of
(a) fluorovinyl ethers having the general formula
(b) fluorovinyl polyethers having the general formula ##STR5##
where X=F or H and n=0-7, and (c)
perfluoro-3,6-dioxa-4-methyl-7-octene sulfonyl fluoride, in a
liquid solvent selected from the class consisting of (a)
perfluorinated solvents (b) chlorofluoroalkanes in which each
carbon atoms has at least one fluorine atom attached thereto and
(c) chlorofluorohydroalkanes in which each carbon atom has at least
one fluorine atom attached thereto and which may contain a maximum
of one hydrogen atom per carbon atom if the hydrogen atom is
present only in the difluoromethyl (CF.sub.2 H) grouping, at a
temperature in the range from 30.degree. C. to about 75.degree. C.
and at pressures in the range of from about 15 to about 1000
p.s.i.g.,
in the presence of a hydrogen-containing chain transfer agent
selected from the group consisting of methanol, isopropanol, and
ethanol thereby to provide a copolymer having stable hydride end
groups.
2. The process of claim 1 in which the solvent is selected from the
group of solvents consisting of CCl.sub.2 F.sub.2,CCl.sub.3 F,
CClF.sub.2 H, CCl.sub.2 FCCl.sub.2 F, CCl.sub.2 FCClF.sub.2, and
CClF.sub.2 CClF.sub.2
3. The process of claim 2 in which the chain transfer agent is
methanol.
4. The process of claim 3 in which the solvent is CCl.sub.2
FCClF.sub.2, the copolymerizable monomer is perfluoropropyl
perfluorovinyl ether and the initiator is bis(perfluoropropionyl)
peroxide.
5. The process of claim 4 in which the copolymerizable monomer is
perfluoroethyl perfluorovinyl ether. .[.6. A tough, stable
copolymer of tetrafluoroethylene with a fluoroalkylperfluorovinyl
ether selected from the group consisting of (a) fluorovinyl ethers
having the general formula XCF.sub.2 (CF.sub.2).sub.n
OCF.dbd.CF.sub.2 wherein X=F or H and n=1-7, (b) fluorovinyl
polyethers having the general formula ##STR6## wherein X=F or H and
n=0-7, and (c) perfluoro-3,6-dioxa-4-methyl-7-octene sulfonyl
fluoride, said copolymer containing stable hydride end groups and
having a volatiles index of less than 25, a swelling index of less
than 25 and a melt viscosity from 1.times.10.sup.4
-100.times.10.sup.4 poises..].
.[.7. The product of claim 6 in which the fluoroalkyl
perfluorovinyl ether is perfluoroethyl perfluorovinyl ether..].
.[.8. The product of claim 6 in which the fluoroalkyl
perfluorovinyl ether is perfluoropropyl
perfluorovinyl ether..]. .Iadd.9. A tough, stable copolymer of
tetrafluoroethylene with perfluoropropyl perfluorovinyl ether, said
copolymer containing stable hydride end groups and having a
volatiles index of less than 25, a swelling index of less than 25
and a melt viscosity from 1.times.10.sup.4 -100.times.10.sup.4
poises. .Iaddend.
Description
BACKGROUND OF THE INVENTION
This invention relates to the polymerization of tetrafluoroethylene
monomer with fluoroalkyl perfluorovinyl ether monomer in a
perfluorinated or saturated nonperfluorinated fluorocarbon solvent
in the presence of a chain transfer agent.
Prior to this invention copolymers of tetrafluoroethylene and
fluoroalkyl perfluorovinyl ether have been polymerized in various
non-aqueous media. The polymers formed in these non-aqueous systems
contain acid fluoride end groups that result from the rearrangement
of the fluorovinyl ether radical on the end of the growing polymer
chain. The rearrangement reaction takes place by the mechanism.
##STR1##
This rearrangement results in the terminal of the polymerization of
that chain by the formation of an acid fluoride end group and a new
free radical group. During storage, these end groups are hydrolized
and decompose during extrusion forming gases which show up as
bubbles in extruded products. This is obviously undesirable. These
end groups can be stabilized by use of the humid heat treatment
process of U.S. Pat. No. 3,085,083 entitled "Stabilized
Tetrafluoroethylene-Fluoroolefin Copolymers Having CF.sub.2 H
End-Groups" which converts the unstable acid end groups into
stable-CF.sub.2 H end groups. The major disadvantages of the humid
heat treatment are that it is slow, adds considerable cost to
polymers that are treated in this manner and also tends to add or
allow contamination of the polymer with dust and other particles
which may be introduced in the heat-treatment process.
Another problem with tetrafluoroethylene/fluorovinyl ether
(TFE/FVE) copolymers is their tendency to swell on being extruded
through small orifices into tubes, wire coating, and the like. This
swelling causes problems in dimension control of the finished parts
but, worse than that, it causes excessive shrinkage of the parts
when they are reheated near the melting point. High swelling resins
have a highly shear stress dependent viscosity indicating a broad
molecular weight distribution. The higher the swelling, the broader
the molecular weight distribution at the same melt viscosity. The
reason for this swelling is that the polymer is viscoelastic and
some of the energy put in to cause flow results in elastic or
recoverable deformation. It is this elastic recovery which causes
the swelling of the polymer as it emerges in viscous flow from an
orifice. A polymer with a broad molecular weight distribution
contains at equal melt viscosity, a larger proportion of very high
molecular weight molecules, which have large elastic components,
than a polymer with narrow molecular weight distribution. Thus, the
former polymer would be expected to swell to a greater degree than
the latter polymer. In certain applications of
tetrafluoroethylene-fluorovinyl ether copolymers it is highly
desirable that the resin undergo little shrinkage when heated near
its melting point. A specific embodiment of this invention on
tetrafluoroethylene/fluorovinyl ether copolymers, prepared in the
presence of methanol as chain transfer agents, is their
considerably reduced tendency to swell upon being extruded and
consequently to shrink when heated near their melting point. As was
stated above, it is believed that the reduction in the swelling
tendency of the copolymer prepared in the presence of methanol is
due to its narrower molecular weight distribution. Another
advantage of the polymers of this invention is their improved
toughness as indicated by their MIT flex life. The MIT flex life
normally increases with melt viscosity and fluorovinyl ether
content of the polymer. Thus, if the fluorovinyl ether content is
held constant, the MIT flex life can be increased by increasing the
melt viscosity of the polymer. Similarly, if the melt viscosity is
held constant, the MIT flex life can be increased by increasing the
fluorovinyl ether content of the polymer. We have found that the
MIT flex life is increased for polymers with the same melt
viscosity and fluorovinyl ether content when they are prepared in
the presence of methanol. It is believed that the increase in
toughness of the polymers prepared in methanol is also due to their
narrower molecular weight distribution relative to polymers
prepared in the absence of methanol. Melt viscosity is a function
of both weight average and number average molecular weights while
toughness is primarily a function of number average molecular
weight. If the molecular weight distribution is narrowed, the ratio
between weight average and number average molecular weight will be
less. Thus, at the same melt viscosity, the polymers with a
narrower distribution will have a higher number average molecular
weight and consequently higher toughness. In certain applications
of tetrafluoroethylene/fluorovinyl ether copolymers it is highly
desirable that the resins have high toughness but still have low
enough melt viscosity (1-100.times.10.sup.-4 poises) for easy
fabrication and contain the minimum amount of the expensive
fluorovinyl ether to be commercially attractive. This is
particularly important in applications such as tank linings and
thin walled tubing which require high stress crack resistance.
As discussed in U.S. Pat. No. 3,085,083, to Schreyer, carboxylate
end-groups in the fluorocarbon polymer chain are the principle
cause of the instability of fluorocarbon polymer at melt
fabrication temperatures. Since acid fluoride end groups. ##STR2##
are the result of the rearrangement of the fluorovinyl ether on the
end of the growing chain and since these are easily converted to
carboxylic acid end groups it can easily be seen that this type of
chain termination will result in polymer instability.
Since it is known that the number of unstable end groups formed on
TFE/FVE copolymers decreases as the molecular weight increases, one
would expect that decreasing the amount of initiator to produce
high molecular weight polymer would decrease instability and
increase the MIT flex life of the polymer. This of course happens,
but there is also a large decrease in the ease of fabricability of
the polymer. Addition of a hydrogen containing chain transfer agent
to the polymerization recipe reduces the number of chain
terminations that are made by rearrangements of the FVE monomer and
increases the number of chain terminations such as those by the
mechanism
The end groups formed by the chain transfer agent are stable
hydride end groups (--CF.sub.2 H), the same end groups that result
from the patented Schreyer process. The resulting polymer has
approximately the same number of unstable acid fluoride end groups
as a much higher molecular weight polymer made by a process without
the chain transfer agent present.
SUMMARY OF THE INVENTION
The invention consists of polymerizing a solution of
tetrafluoroethylene and fluorovinyl ether monomers by a non-aqueous
process similar to that disclosed in U.S. patent application
679,162 to D. P. Carlson filed Oct. 30, 1967.Iadd., now U.S. Pat.
No. 3,528,954, .Iaddend.in the presence of a hydrogen containing
chain transfer agent. The process consists of polymerizing the
monomers in perfluorinated or relatively inexpensive
non-perfluorinated fluorocarbon solvents by initiating the reaction
with low temperature initiator soluble in the solvent monomer
solution. The polymerization is conducted at temperatures from
about 30.degree. C. to about 75.degree. C. and is done in the
presence of a suitable hydrogen containing chain transfer
agent.
The process by which the tetrafluoroethylene/fluoroalkyl
perfluorovinyl ether (TFE/FVE) copolymer can be formed is as
follows:
(a) A suitable fluorocarbon solvent is charged into a stirred
autoclave;
(b) Fluorovinyl ether monomer and a suitable chain transfer agent
are charged into the fluorocarbon solvent;
(c) The solution of step (b) is adjusted to polymerization
temperature and tetrafluoroethylene is charged to bring up the
pressure in the system so the ratio of TFE dissolved in the solvent
to monomer dissolved in the solvent is such so as to produce the
desired polymer;
(d) A low temperature initiator is charged to the autoclave in a
solution of the fluorocarbon solvent;
(e) The pressure in the reactor is maintained throughout the
reaction by continuously adding monomers to the autoclave to
maintain the pressure and comonomer ratio; and
(f) The reaction is allowed to proceed until the desired degree of
polymerization has been reached.
The autoclave is then dumped and the solvent is flashed from the
polymer and recovered.
Suitable solvents for the process are perfluorinated solvents such
as perfluorocyclobutane, perfluorodimethyl cyclobutane and
perfluorocyclohexane. Preferred solvents are commercially available
chlorofluoroalkanes and some chlorofluorohydroalkanes having from
1-4 carbon atoms and preferably 1-2 carbon atoms. The solvents may
be chlorofluoroalkanes in which each carbon atom is substituted by
at least one fluorine atom. Said chlorofluoroalkanes may also
contain a maximum of one hydrogen atom per carbon atom if the
hydrogen is present only in the difluoromethyl grouping (--CF.sub.2
H). Suitable solvents must be liquid at polymerization conditions.
Examples of preferred solvents are as follows: CCl.sub.2 F.sub.2,
CCl.sub.3 F, CClF.sub.2 H, CCl.sub.2 FCCl.sub.2 F, CCl.sub.2
FCClF.sub.2 and CClF.sub.2 CClF.sub.2. These compounds are sold
under the trade names "Freon 12," "Freon 11,", "Freon" 22, "Freon"
112, "Freon" 113 and "Freon" 114, respectively. The most preferred
solvent is "Freon" 113.
The process can be used in polymerization of tetrafluoroethylene
with comonomers that undergo rearrangement to form acid fluoride
groups. One or more of the comonomers can be copolymerized or
terpolymerized with tetrafluoroethylene to produce a co- or
ter-polymer. Examples of preferred monomers which can be
copolymerized with tetrafluoroethylene are as follows: fluorovinyl
ethers having the general formula X CF.sub.2 (CF.sub.2).sub.n
OCF.dbd.CF.sub.2 where X=F or H and n=1-7 such as perfluoroethyl
perfluorovinyl ether, perfluoropropyl perfluorovinyl ether,
3-hydroperfluoropropyl perfluorovinyl ether and isomers thereof;
fluorovinyl polyethers having the general formula ##STR3## where
X=F or H and n=0-7 and isomers thereof; and
perfluoro-3,6-dioxa-4-methyl-7-octene sulfonyl fluoride.
Initators suitable for the process must be soluble in fluorocarbon
solvents and have high activity between about 45.degree. C. and
80.degree. C. Also the initiators must give radicals which will
result in stable end groups on the polymer chain. Fluorocarbon acyl
peroxides are suitable initiators in that they meet the
requirements stated above. Flurorocarbon acyl peroxides which are
suitable for use in the process are represented by the formula
##STR4## where X=H or F and n=1-10. The preferred initiator is
bis(perfluoropropionyl) peroxide. A low temperature initiator must
be used because the temperature of the polymerization system should
not go over about 75.degree. C. Above 75.degree. C. the
rearrangement of the fluorovinyl ether occurs so much more rapidly
that a greater number of claims are terminated in acid fluoride end
groups than can be tolerated.
Carboxylic acid end groups in the polymer are termed "unstable end
groups" because they decompose readily, during fabrication of the
polymer, giving rise to bubbles in the finished product. Other end
groups such as vinyl and acid fluoride end groups are also included
in the category of unstable end groups because they are readily
converted to carboxylic acid end groups.
The existence and quantity of these end-groups in the polymer were
determined by the infrared spectrum generally obtained on
compression molded films of about 10 mils thickness. The end-groups
of interest were found to absorb at 1883 cm..sup.-1, 1814
cm..sup.-1, 1793 cm..sup.-1 and 1781 cm..sup.-1. The 1883
cm..sup.-1 band measures the acid fluoride groups (--COF) in the
polymer. The 1814 and 1781 cm..sup.-1 bands measure the free and
bonded forms, respectively, of the carboxylic acid groups (--COOH).
The 1793 cm..sup.-1 band measures the vinyl end-group
(.sub.[CF.dbd.CF.sub.2). The quantitative measurement of the number
of these groups was obtained by the measurement of the extinction
coefficients of each of these groups from model compounds and
transferring these coefficients to the measurements obtained on the
polymer. Stable-CF.sub.2 H groups were measured in the same way by
use of the 3012 cm..sup.-1 band. Because of the overlapping of some
of the bands it was found necessary to correct the absorbances for
contributions from several groups. The end-groups are expressed as
the number per one million carbon atoms in the polymer.
The term "specific melt viscosity" as used herein means the
apparent melt viscosity as measured at 380.degree. C. under a shear
stress of 6.5 pounds per square inch. Specific melt viscosity is
determined by using a melt indexer of the type described in ASTM
D-1238-52-T, modified for corrosion resistance to embody a
cylinder, orifice, and a piston made of Stellite
cobalt-chromium-tungsten alloy. The resin is charged to the 0.375
inch I.D. cylinder which is held at 380.degree. C..+-.0.5.degree.
C. allowed to come to an equilibrium temperature during 5 minutes,
and extruded through the 0.0825 inch diameter, 0.315 inch long
orifice under a piston loading of 5000 grams. The specific melt
viscosity in poises is calculated as 53,150 divided by the observed
extrusion rate in grams per minute. The stability of the polymer
may also be measured by the volatiles tiles index. In this test, a
10 g. sample of the resin is placed in an aluminum foil thimble,
which is charged into a glass vial attached to a vacuum system. The
vial is evacuated to 2 mm. (Hg) and then on reaching equilibrium,
placed in a hot block maintained at 380.degree. C. The change in
pressure is recorded every ten minutes over a period of 60 minutes.
The volatiles index is calculated by the following equation
##EQU1## where P.sub.40 and P.sub.0 are the pressures of the sample
in mm. prior to insertion and after 40 min. in the hot block and V
is the volume .Iadd.in cc .Iaddend.of the vial.Iadd., and K is
0.1.Iaddend..
It is preferred that the volatiles index be less than 25 because
above this value the amount of bubbles formed on extrusion is
detrimental to the resins properties.
Due to the high molecular weight and insolubility of the
tetrafluoroethylene/fluoroalkyl-perfluorovinyl ether copolymers,
the measurement of their molecular weight distributions by
classical methods is impossible. Instead we have devised a test to
measure the tendency of resins to swell upon being extruded which
we believe to be related to molecular weight distribution as
already discussed above. The "percent swelling" is determined
during the measurement of melt viscosity by the procedure
previously described. The diameter of the strand extruded from the
orifice of the melt indexer is measured and compared with the
diameter of the orifice. The "percent swelling" is the increase in
diameter of the extruded strand versus the diameter of the orifice
as indicated by the equation below.
where D.sub.E =diameter of extrudate; D.sub.D =diameter of
orifice.
For many applications it is desirable that the "percent swelling"
be less than 25. Previous tetrafluoroethylene/fluorovinyl ether
copolymers had "percent swelling" in excess of 50. Polymers
prepared in the presence of methanol have "percent swelling" less
than 25 and usually less than 20.
Several hydrogen containing chain transfer agents can be used to
provide stable end groups on the polymer and overcome the tendency
for the formation of acid fluoride end groups. Specifically,
materials such as methanol, 2-hydroperfluoropropane, cyclohexane,
chloroform, isopropanol, dichloromethane and ethanol are useful for
this purpose. However, of these we have found methanol to be unique
in this system to provide polymers with stable end groups as well
as improved toughness and reduced tendency to swell.
The foregoing process will be exemplified in the following
examples:
Example I
Into an evacuated, one liter, stainless steel, agitated pressure
vessel were charged 860 ml. of
1,2,2-trichloro-1,1,2-trifluoroethane (F-113) and 10.6 grams
perfluoropropyl perfluorovinyl ether (PPVE). The mixture was heated
to 50.degree. C. and tetrafluoroethylene (TFE) was charged into the
vessel until 30 p.s.i.g. pressure was attained. Then 0.74 gram of
perfluoropropionyl peroxide initiator (3-P) was pumped into the
clave as about a 1% solution in F-113. The operating pressure was
maintained by adding additional TFE during the run. The temperature
was controlled by a circulating water system on the jacket side of
the reactor and conventional control elements. After 10 minutes
reaction time, the TFE feed was shut off and the polymer suspension
was removed from the bottom of the reactor. The gel was filtered
using a fritted glass filter and a vacuum flask and the solvent wet
polymer was dried in a circulating air oven at 100.degree. C. for
approximately 16 hours. The polymer was then weighed and
characterized. The dry polymer weighed 63 gm. and had a melt
viscosity of 10.4.times.10.sup.4 poises at 380.degree. C. The
polymer contained 109 unstable end groups per 10.sup.6 carbon atoms
and contained 3.7 wt. percent PPVE. It had an MIT flex life of
57,000.
Example II
Using the procedure of Example I a similar run was performed except
that 16.5 gm. PPVE, 0.10 gm. 3-P initiator and 50 p.s.i.g. pressure
was used. The polymer formed (49.7 gm. in 22 min.) had a melt
viscosity of 170.times.10.sup.4 p., 44 unstable end groups per
10.sup.6 carbon atoms and had a PPVE content of 2.5 wt.
percent.
Example III
A polymerization run identical to Example II using 0.50 ml. of
methanol produced 60.5 gm. of polymer in 33 min. and had a melt
viscosity of 13.5.times.10.sup.4 p., 33 unstable end groups per
10.sup.6 carbon atoms and contained 2.7 wt. percent PPVE. It had an
MIT flex life of 104,000.
Example IV
Using the procedure of Example I a similar run was performed except
that 28 g. of PPVE, 90 p.s.i.g. of TFE and a 60.degree. C.
temperature were used. No methanol was used and 75.8 gm. of polymer
was produced in 11 minutes. The polymer contained 2.8 wt. percent
PPVE, had a melt viscosity of 158.times.10.sup.4 and contained 41
unstable end groups per 10.sup.6 carbon atoms.
Example V
A polymerization run identical to Example IV using 0.50 ml. of
methanol was run and 47 gm. of polymer was produced in 17 minutes.
It contained 2.7 wt. percent PPVE, had a melt viscosity of
10.1.times.10.sup.4 p., and contained 67 unstable end groups per
10.sup.6 carbon atoms.
Using a low initiator concentration and a small amount of methanol
produced a polymer having good melt flow properties and a
sufficiently small number of unstable end groups to maintain a
volatiles index of less than 25 (less than 80 unstable end groups
per 10.sup.6 carbon atoms).
The polymer made where methanol was the chain transfer agent was
much tougher than polymers made without methanol, even though the
PPVE content was lower.
Data from Examples I-V are compiled in Table I.
Examples VI-VIII
A series of polymerizations were carried out using the procedure of
Example I. The ingredients were 1340 gm. of F-113, 28 gm. of PPVE,
0.025 gm. 3-P initiator, and 0-1.0 ml. of methanol. The run
temperature as 50.degree. C. and run pressure was 75 p.s.i.g. In
each case the resulting polymer contained 2.5 wt. percent PPVE. The
melt viscosities and end groups obtained are shown in Table II. The
melt viscosity was decreased by the methanol and the end groups
which were produced were stable CF.sub.2 H end groups.
Examples IX-XVI
A series of polymerizations were carried out using essentially the
same procedure as described in Example I and to the autoclave were
charged 860 ml. F-113 and 28 grams of PPVE. (In some of the
examples either methanol or cyclohexane was also charged at this
point.) The mixture was heated to 60.degree. C. and stirred at 500
r.p.m. TFE was added to bring the total pressure to 90 p.s.i.g.
Then, the desired amount of 3-P solution was added. During the
polymerization, the pressure was maintained at 90 p.s.i.g. by
continuous addition of TFE. The polymerization was usually
continued until the temperature could no longer be controlled and
then the product was dumped from the bottom of the reactor into a
large stainless steel beaker. The polymer was dried in an air oven
at 125.degree. C. overnight. Table III gives a summary of the
reaction conditions for each example and Table IV gives the
properties of the polymers produced.
Examples IX-XII illustrate the effect of initiator concentrations
on polymer properties. As the initiator concentration is increased
the melt viscosity is decreased. However, in all cases the percent
swelling is high (.about.50%) and the number of unstable end groups
increases as well as the volatiles index. Examples XIII and XIV
illustrate the effect of methanol on the polymer. The melt
viscosity is reduced as desired without an increase in unstable end
groups and consequently the volatiles index remains low (<25).
The effect of methanol on percent swelling is also illustrated. The
percent swelling is less than 25 in each case. Examples XV and XVI
illustrate the effect of another chain transfer agent, cyclohexane,
on the polymer. In both cases, the melt viscosity is reduced as
desired without increse in volatiles index. However, the percent
swelling remained high (>50%) in each case.
Examples XVII-XXVI
The MIT flex lives of a number of TFE/PPVE copolymers were
determined. These polymers were made in "Freon"-13 using
perfluoropropionyl peroxide initiator. In some cases methanol was
also used as a chain transfer agent. The data are reported in Table
V. The flex life is seen to increase with PPVE content and melt
viscosity for a series of similarly produced polymers. The polymers
made using methanol had substantially higher flex lives than
polymers of similar PPVE contents and melt viscosities made without
methanol.
TABLE I
__________________________________________________________________________
Polymer Properties Melt Reagents Conditions Run Weight viscosity
MIT F-113.sup.1 PPVE.sup.2 3-P.sup.3 MeOH Temp. Pres. Time Polymer
Percent (poises End flex Example (gm.) (gm.) (gm.) (ml.)
(.degree.C.) (p.s.i.g.) (min.) (gm.) PPVE .times. 10.sup.-4)
groups.sup.4 life
__________________________________________________________________________
I 1,340 10.6 0.74 0 50 30 10 63 3.7 10.4 109 57,000 II 1,340 16.5
0.10 0 50 45 22 49.7 2.5 170 44 III 1,340 16.5 0.10 0.50 50 45 33
60.5 2.7 13.5 33 104,000 IV 1,340 28 0.10 0 60 90 11 75.8 2.8 158
41 V 1,340 28 0.10 0.50 60 90 17 47 2.7 10.1 67
__________________________________________________________________________
.sup.1 1,1,2trichloro-1,2,2-trifluoroethane. .sup.2 Perfluoropropyl
perfluorovinyl ether. .sup.3 Perfluoropropionyl peroxide. .sup.4
COF, COOH, COOMe, and CF.dbd.CF: end groups per 10.sup.4 C
atoms.
TABLE II
__________________________________________________________________________
Melt viscosity MeOH .times. 10.sup.-4 poises End groups per
10.sup.4 C atoms Example (ml.) (380.degree. C.) COF COOH (M)
CF.dbd.CF.sub.2 COOH (D) COOMe CF.sub.2 H
__________________________________________________________________________
VI 0 854 28 1 63 VII 0.50 17.1 14 3 6 127 VIII 1.00 3.6 13 11 21 3
19 178
__________________________________________________________________________
TABLE III
__________________________________________________________________________
POLYMERIZATION CONDITIONS FOR EXAMPLES IX THROUGH XVI Poly- F113
PPVE MeOH Cyclohexane 3-P* Pres Temp. Time mer Example (ml.) (g.)
(ml.) (ml.) (g.) (p.s.i.g.) (.degree.C.) (min.) (g.)
__________________________________________________________________________
IX 860 28 .025 90 60 38 81 X 860 28 .05 90 60 12 74.2 XI 860 28 .10
90 60 5 66.5 XII 860 28 .10 90 60 2 29.5 XIII 860 28 0.10 0.25 90
60 61 96.7 XIV 860 28 0.5 .025 90 60 60 86.3 XV 860 28 0.10 .05 90
60 41 83.1 XVI 860 28 0.20 .05 90 60 60 65.8
__________________________________________________________________________
*3-P added as solution in F113.
TABLE IV ______________________________________ PROPERTIES OF
POLYMERS FROM EXAMPLES IX-XVI Melt viscosity Unstable Weight
(380.degree.) end groups, percent .times. 10.sup.-4 Percent
No./10.degree. C. Volatiles Example PPVE poises swelling atoms
index ______________________________________ IX 2.41 464 47 60 28 X
2.59 149 55 62 32 XI 3.22 44.2 53 138 36 XII 3.45 10.8 57 284 46
XIII 2.68 28.0 15 65 13 XIV 2.36 8.6 13 70 13 XV 2.45 59 52 33 XVI
2.41 18 59 21 ______________________________________
TABLE V ______________________________________ MIT FLEX LIFE OF
TFE/PPVE COPOLYMERS Melt viscosity, Weight .times. 10.sup.-4 Chain
transfer percent poises MIT flex Example agent PPVE (380.degree.
C.) life ______________________________________ XVII None 2.8 13
22,000 XVIII " 2.7 18 73,000 XIX " 3.2 13 51,000 XX " 3.4 4 5,000
XXI " 3.1 4 6,000 XXII Methanol 2.7 13 104,000 XXIII " 2.7 11
59,900 XXIV " 2.6 4 12,000 XXV " 2.5 17 227,800 XXVI " 7.0 8
1,750,000 ______________________________________
* * * * *