Note: Descriptions are shown in the official language in which they were submitted.
729~
This invention relates to a novel fluorine-
containing crosslinkable copolymer. More particu-
larly, the present invention is concerned with a
fluorine-containing crosslinkable copolymer comprising
fluorine-containing monomer units each having a
sulfonyl chloride group and monomer units of at least
one ethylenically unsaturated compound, which can be
easily crosslinked to give a crosslinked elastomeric
product which is excellent in heat resistance and
chemicals resistance.
In recent years, various fluorine-containing
plastic products and elastomeric products have been
used in a variety of industrial fields such as auto
industry, shipping industry, aircraft industry,
hydraulic equipment industry and the other machine
industries and in the fields associated with preven-
tion of environmental pollution, because of their
excellent heat resistance, solvent resistance and
corrosion resistance. The range of their use has been
expanded and, there~ore, the demand for fluorine-
containing plasti~ products and elastomeric products
has been increased.
The fluorine-containing plastic products and
elastomeric products are produced from a fluorine-
containing polymer. Therefore, various studies have
-- 2
~47291
been made with a view to developing a fluorine-
containing polymer which is useful to give a plastic
product or an elastomeric product having excellent
properties, such as heat resistance, solvent resis-
tance and corrosion resistance.
The present inventors also have made extensive
and intensive studies to develop an excellent
fluorine-containing polymer. As a result, it has been
found that a fluorine-containing crosslinkable
copolymer which comprises fluorine-containing monomer
units each having a sulfonyl chloride group as an
active group for crosslinking and monomer units of at
least one ethylenically unsaturated compound and of
which the sulfonyl chloride group content is in a
specific range is capable of being easly crosslinked
to give an elastomer which exhibits excellent heat
resistance and chemicals resistance. The present
invention has been completed based on this novel ~ind-
ing
It is, therefore~ an object of the present inven-
tion to provide a novel fluorine-containing cross-
linkable copolymer which is capable of being easily
crosslinked to give an elastomer which is excellent in
heat resistance and chemicals resistance.
~L2~7Z~
The foregoing and other objects, features and
advantages of the present invention will be apparent
to those skilled in the art from the following
detailed description.
According to the present in~ention, there is
provided a fluorine-containing crosslinkable copolymer
comprising:
(A) fluorine-containing monomer units each having
a sulfonyl chloride group and represented by the
following general formula ~I):
CF2=cF~cF2~o~cF2clFo ~ CF2~nSO2Cl (I)
CF3
wherein Q is 0 or 1, m is 0, 1 or 2, and n
is an integer of from 1 to 4; and
(B) monomer units of at least one ethylenically
unsaturated compound represented by the following
general formula (II):
CX1X2=Cx3x4 (II)
wherein X1 and X2 each independently stand
for a fluorine atom, a hydrogen atom or a
chlorine atom, and X3 and X~ each indepen-
dently stand for a fluorine atom, a hydrogen
atom, a chlorine atom, a methyl group, a
trifluoromethyl group, or a group repre-
sented by the following formula (III):
-- 4 --
~2~72~
-(OCF2FF)pO(CF2)qF (III)
CF3
(wherein p is 0, 1 or 2 and q is an integer
of from 1 to 3),
and which copolymer has a sulfonyl chloride group
content of about 0.1 to 3.0 % by weight based on the
total weight of (A) and (B) and has an intrinsic
viscosity of at least 0.01 dl/g as measured at 30 C.
The fluorine-containing crosslinkable copolymer
of the present invention contains sulfonyl chloride
groups. The sulfonyl chloride groups serve as active
groups for crosslinking. In the present invention, in
order that the fluorine-containing copolymer may be
easily crosslinked to give an excellent elastomer, it
is requisite that the sulfonyl chloride group content
of the copolymer be about 0.1 to about 3.0 % by weight
based on the total weight of copolymer constituents
(A) and (B) which will be mentioned later. When the
sulfonyl chloride group content is less than about
0.1 % by weight, the amount o~ active groups for
crosslinking is too small for the fluorine-containing
copolymer to crosslink sufficiently and, therefore, an
elastomer which is excellent in heat resistance and
chemicals resistance cannot be obtained. On the other
~729~L
hand, when the sulfonyl chloride group content exceeds
about 3.0 % by weight, the crosslink density of the
crosslinked copolymer becomes high so that, as shown
in the later-given Comparative Example 1 and
Application Example, the elastomeric characteristics
of the crosslinked copolymer become extremely poor,
that is, the elongation of the crosslinked copolymer
becomes considerably small and when the compressive
stress is applied to the crosslinked copolymer, the
crosslinked copolymer tends to be easily cracked. ~he
sulfonyl chloride group content of the fluorine-
containing copolymer may be determined by a customary
infrared analysis method in which an infrared
absorption at 1410 cm~l is measured.
With respect to fluorine-containing copolymers
having sulfonyl chloride groups but having a sulfonyl
chloride group content of more than about 3.0 % by
weight, there are ~onventionally known precursors for
the production of ion exchange membranes. ~or
example, sulfonic acid type ion exchange membranes and
carboxylic acid type ion exchange membranes are
produced utilizing the active sulfonyl chloride groups
of fluorine-containing polymers having a sulfonyl
chloride group content of about 5.0 % by weight or
~4729~
more (U.S. Patent Nos. ~,166,014 and 4,151,053). Such
fluorine-containing polymers having sulfonyl chloride
group are prepared by subjecting fluorine-containing
polymers having sulfonic group to chemical modifica-
tion so that the sulfonic groups are converted to
sulfonyl chloride groups. It should be noted,
however, that in the production of the above-mentioned
ion exchange membranes, the sulfonyl chloride groups
of such fluorine-containing polymers are not utilized
as active groups for crosslinking. Further, it should
be noted that in the above-mentioned chemical modifi-
cation of the sulfonic groups to sulfonyl chloride
groups, due to the high reactivity and high diffusion
of the modifying agent used in such a chemical modifi-
cation, it is impossible to obtain a fluorine-contain-
ing polymer of which the sulfonyl chloride group
content is controlled to an extent as small as about
0.1 to about 3.0 % by weight and in which sulfonyl
chloride group are uniformly distributed.
On the other hand, the present fluorine-contain-
ing crosslinkable copolymer having sulfonyl chloride
groups is prepared by copolymerizing a fluorine-
containing monomer having a sulfonyl chloride group
with a monomer of at least one ethylenically
unsaturated compound and, therefore, the sulfonyl
7~
chloride group content of the resulting copolymer can
be easily controlled by changing the amount ratio of
the fluorine-containing monomer having a sulfonyl
chloride group to the monomer of at leas-t one
ethylenically unsaturated compound. Therefore, a
fluorine-containing copolymer of which the sulfonyl
chloride group content is as small as about 0.1 to 3 %
by weight and in which sulfonyl chloride groups are
uniformly distributed can be easily obtained. From
1~ the fluorine-containing copolymer having a sulfonyl
chloride group content of about 0.1 to 3 % by weight,
there can be obtained a crosslinked elastomeric
product having excellent heat resistance and chemicals
resistance.
The copo~ymer constituent ~A) of the fluorine-
containing crosslinkable copolymer of the present
invention is monomer units of a compound represented
by the following general formula (I):
CF2=cF~c~2~o~cF2lcFo ~ CF2)nS02Cl (I)
~0 CF3
(wherein Q is O or 1, m is 0, 1 or 2, and n is an
integer of from 1 to 4)
Such a compound can be prepared from a known
compound by a customary method. Such a compound can
be readily synthesized from the corresponding
fluorine-containing monomer compound having a sulfonyl
fluoride group or a sulfonic group. For example, a
compound represented by the above formula (I) in which
Q=0, m=0 and n=3 can be prepared as follows:
aqueous NaOH
CF2=CF0 1 CF2 ) 3S02F --
CF2=CFO ( CF2 ) 3S03Na
PC15
CF2=CFO ( CF2 ) 3S2Cl
The copolymer constituent (B) of the fluorine-
containing crosslinkable copolymer of the present
invention is monomer units of at least one ethyleni-
cally unsa-turated compound represented by the follow-
ing general formula (II):
CX1X2=cx3x4 (II)
wherein X1 and X2 each independently stand for a
- fluorine atom, a hydrogen atom or a chlorine atom, and
X3 and X4 each independently stand for a fluorine
atom, a hydrogen atom, a chlorine atom, a methyl
group, a trifluoromethyl group, or a group represented
by the following formula (III):
~~OCF2CF~pO(CF2)qF (III)
(wherein p is 0, 1 or 2 and q is an integer of
_ g _
1~7~g~
from 1 to 3).
As preferable examples of the ethylenically un-
saturated compound, there may be mentioned tetra-
fluoroethylene, hexafluoropropylene, a perfluoroalkyl-
perfluorovinyl ether, vinylidene fluoride, ethylene,
propylene, pentafluoropropylene and chlorotrifluoro-
ethylene. They may be employed alone or in mixture~
In order to attain the effect of the present inven-
tion, it is preferable that two or more kinds of the
above-mentioned ethylenically unsaturated compounds,
in combination, be employed as the copolymer consti-
tuent (B). In this connection, it is noted that when
a monomer compound which has relatively poor poly-
merizability such as hexafluoropropylene is chosen as
the constituent (B~, another monomer compound which
has ~ood polymerizability such as tetrafluoroethylene
should preferably be used in combination therewith.
As preferable combinations of the ethylenically
unsaturated compounds, there may be mentioned (1) a
combination of tetrafluoroethylene and a perfluoro-
alkylperfluorovinyl ether, (2~ a combination of vinyl-
idene fluoride, hexafluoropropylene, tetrafluoro-
ethylene and a perfluoroalkylperfluorovinyl ether, (3)
a combination of vinylidene fluoride and hexafluoro-
- 10 -
~24~7291
propylene, and (4) a comblnation of tetrafluoroethylene,
vinylidene fluoride and hexafluoropropylene. Of them,
a combination of tetrafluoroethylene and a perfluoroalkyl-
perfluorovinyl ether represented by the general formula
CF2=CFO(CF2)nCF3 (wherein n is 0, 1 or 2) is most
preferable as the copolymer constituent (~).
In order to provide a fluorine-containing cross-
linkable copolymer which, upon being crosslinked, is
capable of giving an elastomer having the desired properties,
it is preferred that the following combination of ethylen-
ically unsaturated compounds be used as the constituent
(B):
(1) 50 to 85 % by mole of tetrafluoroethylene and
15 to 50 % by mole of a perfluoroalkylperfluorovinyl
ether, based on the total mole of (B),
(2) 40 to 75 % by mole of vinylidene fluoride, 0
to 30 % by mole of hexafluoropropylene, 0 to 25 % by
mole of tetrafluoroethylene and 0 to 20 % by mole of
a perfluoroalkylperfluorovinyl ether, based on the total
mole of (B),
(3~ 70 to 80 % by mole of vinylidene fluoride and
20 to 30 % by mole of hexafluoropropylene, based on total
mole of (B), or
(4) 15 to 20 % by mole of tetrafluoroethylene, 60
-- 11 --
". . ~ .
'72~
to 65 ~O by mole of vinyliden fluoride, and 15 to 25 %
by mole of hexafluoropropylene, based on the total mole
of (B).
It is most preferable to employ, as the constituent
(B), a combination of 50 to 85 ~O by mole of tetrafluoro-
ethylene and 15 to 50 % by mole of a perfluoroalkylper-
fluorovinyl ether, based on the total mole of (B).
As is apparent from the above, the preferable
ethylenically unsaturated compound is a fluorine-
containing ethylenically unsaturated compound havingno C-H bond or having few C-H bonds. Such ethylenically
unsaturated compounds have, on one hand, an advantage
that when the ethylenically unsaturated compound is used
as a constituent of a copolymer, the copolymer is capable
of giving an elastomer having the desired properties.
On the other hand, such ethylenically unsaturated compounds
have a disadvantage that the ethylenically unsaturated
compound has no active groups or fe~ active groups for
crosslinking and, therefore, it is difficult to crosslink a
copolymer comprising the ethylenically unsaturated compound.
According to the present invention, however, the
copolymer is prepared by copolymerizing the ethyleni-
- 12 -
~2~729~
cally unsaturated compound with the fluorine-contain-
ing monomer having a sulfonyl chloride group, that is,
the copolymer of the present invention has sulfonyl
chloride groups as active groups for crosslinking.
Therefore, the copolymer of the present invention can
be easily crosslinked to give an elastomer having the
desired properties.
As mentioned above, the fluorine-containing
crosslinkable copolymer of the present invention is
prepared by copolymerizing the fluorine-containing
monomer having a sulfonyl chloride group and the
monomer of at least one ethylenically unsaturated
compound. The copolymerization may be performed in
the presence of a free radical initiator according to
known polymerization methods such as a bulk poly-
merization method, a suspension polymerization method,
a emulsion polymerization method, a solution polymeri-
zation method and the like. In this connection,
however, if the copolymerization is performed using an
aqueous solvent according to an emulsion polymeriza-
tion method, a suspension polymerization method or a
solution polymerization method, the decomposition of
sulfonyl chloride groups may occur to some extent.
Therefore, when the copolymerization is carried out
according to t~e suspension polymerization method,
~2~iL7Z9~
emulsion polymerization method or solution polymeriza-
tion method, it is preferred to carry out the copoly-
merization in an organic solvent.
As examples of the organic free radical initiator
which can be used for preparing the copolymer of the
present invention, there may be mentioned, for
example, azobisisobutyronitrile, benzoyl peroxide and
fluorine type free radical initiators such as per-
fluorobutanoyl peroxide. Of them, perfluorobutanoyl
peroxide may be most preferable. The amount of the
organic free radical initiator may be varied dependinq
on the kind of the free radical initiator, the temper-
ature and the polymerizability of the monomers. sut,
in general,the amount of the initiator may be in the
range of about 0.005 to 0.5 ~ by weight based on the
total weight of the reaction system.
As the organic solvent which can be used in the
copolymerization, it is preferred to employ such a
solvent as will not act as a chain transfer agent and
is capable of dissolving the monomers used and the
copolymers formed. As examples of such an organic
solvent, there may be mentioned halogenated hydro-
carbons such as l,1,2-trichloro-1,2,2-trifluoroethane,
1,2-dichloro-1,1,2,2-tetrafluoroethane, trichloro-
- 14 -
~2~72g~L
fluoromethane, dichlorodifluoromethane, perfluoro-
cyclobutane and the like.
The reaction conditions such as polymerization
pressure and polymerization temperature may be widely
varied depanding on the composition of the intended
copolymer, the kind of free-radical initiator and the
kind of polymerization method. But, the copolymeriza-
tion reaction may generally be effected at a temper-
ature of 20 to 90 C under a pressure of 1.0 to
50 kg/cm2-Gauge.
The thus prepared fluorine-containing crosslink-
able copolymer of the present invention essentially
comprises the monomer units (A) and (B). However, the
copolymer of the present invention may contain a small
amount of the other compounds, such as an organic free
radical initiator.
With respect to the thus obtained fluorine-
containing crosslinkable copolymer of the present
invention, the determination of sulfonyl chloride
g}oup content and the amount oE each monomer unit
constituting the copolymer can be made by a customary
infrared absorption analysis, an elemental analysis, a
19F-~MR analysis and the like.
The fluorine-containing crosslinkable copolymer
of the present invention has an intrinsic viscosity of
- 15 -
~7~9~L
at least 0.01 dl/g, preferably 0.1 to 3.0 dl/g as
measured at 30 C. The intrinsic viscosity can be
obtained from the values of the solution viscosities.
The solution viscosities are obtained by measuring the
viscosities of the solutions of the copolymer by means
of an Ostwald's viscometer. The solutions of the
copolymer are prepared by dissolving 0.1 g of the
copolymer in 100 g of 2,3-dichlorooctafluorobutane.
The fluorine-containing copolymer of the present
invention can be crosslinked with the aid of an
organic peroxide, heat, light, radioactive rays or the
like utilizing the chemical reactivity of sulfonyl
chloride groups. It is most preferred that the cross-
linking reaction be effected using an organic per-
oxide.
As the organic peroxide, there may be mentioned
such dialkyl peroxides as serve as a crosslinking
agent at an elevated temperature but will not cause
any crosslinking during the preliminary procedure such
as blending of the copolymer with the peroxide and the
subsequent kneading. As suitable examples of such
organic peroxide, there may be mentioned, 2,5-
dimethyl-2,5-di(t-butylperoxy~hexane, 2,5-dimethyl-
2,5-di(t-butylperoxy)hexyne, 1,3-di~t-butylperoxy-
~7Z91
isopropyl)benzene, 1,1-di(t-butylperoxy)-3,3,5-
trimethylcyclohexane and the like. These organic
peroxides may usually be employed in an amount of 0.5
to 5 % by weight based on the weight of the copolymer
of the present invention.
For performing sufficient crosslinking of the
copolymer, it is preferred that an auxiliary cross-
linking agent be used in combination with the organic
peroxide. As the auxiliary crosslinking agent, it is
preferred to employ multi-functional compounds which
coact with the organic peroxide. ~s such multi-
functional compounds, there may be mentioned, for
example, triallyl isocyanurate, triallyl cyanurate,
triallyl phosphite, N,N,N',N'-tetraallylterephthal
amide and the like. Of them, triallyl isocyanurate is
most preferable. The auxiliary crosslinking agent may
be employed in an amount oE 0.5 to 7 % by weight based
on the weight of the copolymer.
The crosslinking of the Eluorine-containing
copolymer of the present invention may be effected as
follows. Firstr to the copolymer of the present
invention are added the above-mentioned organic per-
oxide and auxiliary crosslinking agent, and, according
to need, known additives such as a metal oxide, a
~5 metal hydroxide and carbon black, and the resulting
:~Z~7Z9~
mixture is sufficiently kneaded using a roll, a
Banbury type mixer or the like to form a homogeneous
composition. Second, the thus-obtained composition is
heated at a temperature of 120 to 200 C for 1 to 60
minutes by means of a press, mold or extruder, thereby
to perform primary crosslinking of the copolymer.
Thereafter, if desired, the copolymer thus primarily
crosslinked may preferably be further heated at a
temperature of 160 to 300 ~C for 1 to 48 hours,
thereby to perform secondary crosslinking of the
copolymer so that the thermal stability and dimen-
sional stability of the crosslinked product can be
improved. Thus, there is obtained an fluorine-
containing elastomer having excellent properties, such
as heat resistance and chemicals resistance.
The novel fluorine-containing copolymer of the
present invention has sulfonyl chloride groups as
active groups for crosslinking. Due to the presence
of the sulfonyl chloride groups, the fluorine-contain-
ing copolymer of the present invention can be easily
crosslinked to give an elastomer. The thus obtained
elastomer has excellent properties, such as creep
resistance, heat resistance, solvent resistance, etc.
Therefore, it is expected that by the use of the
- 18 -
~7'~
copolymer of the present invention, there can be
advantageously obtained fluorine-containing elastomers
useful in the fields of auto lndustry, shipping
industry, aircraft industry, hydraulic equipment
industry and the other machine industries, and in the
fields associated with prevention oE environmental
pollution.
The present invention will now be described in
detail with reference to the following Referential
Example, Examples and Comparative Example, which
should not be construed to be limiting the scope of
the present invention.
Referential Example
Production of perfluoro(3-chlorosulfonyl)propylvinyl
ether [CF2=CFO(CF2)3SO2Cl]
Into a three-necked flask equipped with a stirrer
and having a capacity of 1 liter is charged 400 g of a
15 % by weight aqueous NaOH solution and the inner
temperature of the flask is kept at 50 C by means of
a water bath. 245 g of CF2=CFo(CF233SO2F is gently
dropwise added to the ~lask while stirring. The reac-
tion proceeds smoothly and after 3 hours, the reaction
is completed. After the water in the obtained reac-
tion mixture is removed by means of an evaporator, the
-- 19 --
7Z9~
solid residue is dried under reduced pressure at 80 C
for 40 hours. Thus, there is obtained 290 g of a
white powder. The white powder sample is subjected to
infrared absorption analysis to obtain the infrared
absorption spectrum. Illustratively stated, a sample
is applied to a KBr plate, and another KBr plate is
covered over the sample-applied plate to sandwich the
sample therebetween. Then, using IR-440 (trade name
of an infrared spectrometer manufactured by Shimadzu
Corporation, Japan), IR spectrum is taken at room
temperature between the wavelengths of 5040 cm~1 and
400 cm~1. The examination of the IR spectrum shows
that the sample exhibits a strong absorption at
1050 cm~1 attributed to -SO3Na.
Into a three-necked flask equipped with a stirrer
and having a capacity of 1 liter are added 290 g of
the above-obtained white powder and, then, 313 g of
phosphorus pentachloride and 100 g of phosphorus oxy-
chloride. The flask is heated by means of an oil bath
to raise the inner temperature of the flask gradually,
~hile gently stirring, to 120 C over 2 hours, and the
reaction is allowed to proceed at this temperature for
16 hours.
After completion of the reaction, the reaction
- 20 -
~.Z~L7291
mixture is cooled and poured into water little by
little to hydrolyze the phosphorous oxychloride and
the excess of phosphorous pentachloride. The mixture
is allowed to stand to separate into two layers.
After the separation into two layer, the lower layer
is collected and distilled under reduced pressure to
obtain 175 g of a distillate having a boiling point of
72 C (80 mmHg)O
The obtained distillate is a transparent, color-
less and odorless liquid. Infrared absorption
spectrum with respect to the distillate is obtained in
substantially the same manner as described above. As
a result, it is found that the distillate shows an
absorption at 1840 cm~1 attributed to the vinyl ether
group and an absorption at 1410 cm~1 attributed to the
sulfonyl chloride group. The purity of the product is
determined using GC-3BT (trade name of an apparatus
for gas chromatography manufactured by Shimadzu Corpo-
ration, Japan) under the following conditions:
Detector: Thermal conductivity detector (TCD)
Carrier gas: He gas
Solid support: KRYTOX/Chromosorb (trade name of a
solid support manufactured and
sold by E.I. Du Pont de Namours
~5 and Company, U.S.A.) (column
- 21 -
~2~7~9~
length: 3 m)
Column temperature: 120 C
As a result, it is found that the purity of the
product is 99 %. The results of the elemental analy-
sis of the product are well in agreement with the
calculated values as follows:
Element C F S Cl
Calculated: 17.3 % 49.35 % 9.25 % 10.25 %
Found: 17.2 % 49.2 ~ 9.3 % 10.4 %
Example 1
After the air in an autoclave having a capacity
of 3 liters and made of a stainless steel is complete-
ly replaced by nitrogen gasj the autoclave is evacu-
ated to remove the nitrogen gas. Then, 1500 g of
perfluoropropylperfluorovinyl ether (hereinafter
referred to as "PPVE") and 18 g of perfluoroE3-
~chlorosulfonyl)propylvinyl ether~ (hereinafter refer-
red to as "3-CSVE") are charged into the autoclave and
are gently stirred at 25 C. Then~ 1.5 g of per-
fluorobutanoyl peroxide (hereinafter referred to as
"PBP") is poured into the autoclave by means of a
~2~7;~9~
glass ampule and, thereafter, tetrafluoroethylene
(hereinafter referred to as "TFE") is introduced into
the autoclave until the inner pressure of the auto-
clave ~ecomes 4.8 kg/cm2 so that the polymerization
reaction is caused to start. The polymerization reac-
tion is effected while stirring at 300 rpm.
Since the pressure is gradually decreased with
the progress of the polymerization reaction, the pres-
sure is maintained at 4.8 kg/cm2 by adding TFE gas.
The polymerization reaction is stopped 7 hours after
the start of the polymerization reaction. The total
amount of TFE gas introduced into the autoclave is
65 g.
Then, TFE, PPVE and 3-CSVE which remain unreacted
are removed from the autoclave to obtain a solid
residue. The solid residue is washed with Freon 113
(manufactured and sold by E.I. du Pont de Namours and
Company, U.S.A.), and dried under vacuum at 90 C to
obtain 150 g of a white elastic copolymer of TFE-PPVE-
3-CSVE.
The obtained copolymer is subjected to elemental
analysis and infrared absorption analysis to determine
the composition of the copolymer and the sulfonyl
chloride group content of the copolymer. As a result,
- ~3 -
~Z~72~
it is found that the obtained copolymer comprises
65.5 % by mole of TFE monomer unit, 33.5 % by mole of
PPVE monomer unit and 1.0 % by mole of 3-CSVE. The
sulfonyl chloride group content of the copolymer is
found to be 0.63 % by weight based on the copolymer.
The intrinsic viscosity of the copolymer is 0.65 dl/g
at 30 C.
Comparative Example 1
Substantially the same procedures as in Example 1
are repeated except that instead of 18 g of 3-CSVE,
100 g of 3-CSVE is charged, to obtain 155 g of white
elastic copolymer of TFE-PPVE-3-CSVE
It is found that the obtained copolymer comprises
62.0 % by mole oE TFE monomer unit, 32.0 % by mole of
PPVE monomer unit and 6.0 96 by mole of 3-CSVE. The
intrinsic viscosity and sulfonyl chloride group -
content of the obtained copolymer are found to be
0.55 dl/g at 30 C and 3.53 % by weight based on the
total weight of the copolymer, respectively.
Example 2
The air in an autoclave having a capacity of 3
liters and made of a stainless steel is completely
removed. Then, 2000 g of 1,1,2-trichloro-1,2,2-
-- 24 --
~7~
trifluoroethane (hereinafter referred to as "R~113"),
1000 g of PPVE and 40 g of 3-CSVE are charged into the
autoclave and gently stirred at 25 C. Then, 2.15 g
of PBP is poured into the autoclave by means of a
glass ampule and, thereafter, TFE is introduced into
the autoclave until the inner pressure of the auto-
clave becomes 1.8 kg/cm2 so that the polymerization
reaction is caused to start. The polymerization reac-
tion is effected while stirring at 300 rpm.
Since the TFE pressure is gradually decreased
with the progress of polymerization reaction, the
pressure is maintained at 1.8 g/cm2 by adding TFE.
The polymerization reaction is completed 20 hours
after the start of polymerization reaction.
Then, TFE, PPVE and 3-CSVE which remain unreacted
are removed from the autoclave to obtain a solid
residue. The solid residue is washed with Freon 113
Imanufactured and sold by E.I. Du Pont de Namours and
Company, U.S.A.), and dried under vacuum at 90 C to
obtain 250 g of a white elastic copolymer of TFE-PPVE-
3-CSVE.
It is found that the obtained copolymer comprises
65 ~ by mole of TFE monomer unit, 33.5 % by mole of
PPVE monomer unit and 1.5 ~ by mole of 3-CSVE monomer
unit. The intrinsic Yiscosity and sulfonyl chloride
- 25 -
12~729~
group content of the obtainecl copolymer are found to
be 0.55 dl/g at 30 C and 0.94 % by weight based on
the total weight of the copolymer, respectively.
Example 3
The air in an au-toclave having a capacity of 3
liters is completely removed. Then, 2500 g of R-113
and 12 g of 3-CSVE are charged into the autoclave and
gently stirred at 25 C. Separately, 0.5 g of PBP is
dissolved in 10 g of R-113 to obtain a solution. The
thus-obtained solution is poured into the autoclave by
means of a glass ampule. Then, a gas mixture consist-
ing of 43.4 % by mole of vinyldene fluoride (herein-
after referred to as "VdF") and 56.6 % by mole of
hexafluoropropylene ~hereinafter referred to as "HFP")
is introduced into the autoclave until the inner pres-
sure of the autoclave becomes 10 kg/cm2 so that the
polymerization reaction is caused to start. The poly-
merization reaction is effected while stirring at
300 rpm. Since the pressure is decreased with the
progress of polymerization reaction, the pressure is
maintained at 10 kg/cm2 by adding a gas mixture
consisting of 76.8 ~ by mole of VdF and 23.2 % by mole
of HFP. The polymerization reaction is completed 7
~47z9~
hours after the start of polymerization reaction.
Then, VdF, HFP and 3-CSVE which remain unreacted
are removed from the autoclave to obtain a solid
residue. The solid residue is washed with Freon~113
(manufactured and sold by E.I. Du Pont de Namours and
Company, U.S.A.), and dried under vacuum at 90 C to
obtain 80 g of a white elastic copolymer of VdF-HFP-3-
CSVE.
The obtained copolymer is subjected to 19F-NM~
analysis. As a result, it is found that the copolymer
comprises 72 % by mole of VdF monomer unit, 27.3 % by
mole of HFP monomer unit and 0.7 % by mole of 3-CSVE
monomer unit~ The intrinsic viscosity of the copoly-
mer is determined in methyl ethyl ketone at 35 C and
found to be 0.6 dl/g. The sulfonyl chloride
group content of the copolymer is found to be 0.77 %
by weight based on the total weight of the copolymer.
Example 4
The air in an autoclave having a capacity of 3
liters is completely removed. Then, 2500 g of R-113,
12 g of 3-CSVE and 0.5 g of PBP are charged into an
autoclave. While gently stirring at 25 C, a gas
mixture consisting of 55 ~ by mole of TFE and 45 % by
mole of perfluoromethylper~luorovinyl ether (herein~
- 27 -
~ ~rad~ r l~
~2~7;~9~
after referred to as "PMVE") is introduced into the
autoclave until the inner pressure of the autoclave
becomes 8 ~g/cm2 so that the polymerization reaction
is casue~ to start. The polymeri~ation reaction is
carried out while stirring at 300 rpm. The polymeri-
zation reaction is completed 5 hours after the start
of polymerization reaction. Then, TFE PMVE and 3-CSVE
which remain unreacted are removed from the autoclave
to obtain a solid residue. The solid residue is
washed with Freon 113 (manufactured and sold by E.I.
Du Pont de Namours and Company, U.S.A.), and dried
under vacuum at 90 C to obtain ~8 g of a white
elastic copolymer of TFE-PMVE-3-CSVE.
The obtained copolymer is subjected to infrared
absorption analysis and it is found that tne copolymer
comprises 66.5 % by mole of TE'E monomer unit, 33 % by
mole of PMVE monomer unit and 0.5 % by mole of 3-CSVE
monomer unit. The sulfonyl chloride group content of
the copolymer is found to be 0.42 % by weight based on
the total wei~ht of the copolymer.
Example 5
In substantially the same manner as in Referen-
tial Example, perfluoro[2-(2-chlorosulfonylethoxy)~~
- 28 -
~72gl
propylvinyl ether (hereinafter referred to as "2-
CSEVE") is synthesized from perfluoro[2-(2-fluoro-
sulfonylethoxy)]propylvinyl e-ther.
After the air in an autoclave having a capacity
of 3 liters and made of a stainless steel is complete-
ly replaced by nitrogen gas, the autoclave is evacu-
ated to remove the nitrogen gas. Then, 1500 g of PPVE
and 2 g of the above-obtained 2-CSEVE are charged into
the autoclave and are gently stirred at 25 ~C. Then,
TFE is introduced into the autoclave until the inner
pressure of the autoclave becomes 4.8 kg/cm2
Subsequently, 1.5 g of PBP as a polymerization initi-
ator is added so that the polymerization reaction is
caused to start. The polymerization reaction is
terminated 7 hours after the start of polymerization
reaction. The monomers remaining unreacted are
recovered and 150 g of a white elastic copolymer of
TFE-PPVE - 2- CSEVE i s obtained.
It is found that the copolymer comprises 65.5 %
2~ by mole of TFE monomer unit, 33.3 % by mole of PPVE
monomer unit and 1.2 % by mole of 2-CSEVE. The
sulfonyl chloride group content of the copolymer is
found to b~ 0.8 % by weight based on the total weight
of the copolymer.
-- 2g --
~2~7~9~
Example 6
Substantially the same procedures as in Example 5
are repeated except that perfluoro[2-(3-chloro-
sulfonylpropoxy)]propylvinyl ether (hereinafter refer-
red to as "3-CSPVE") is used instead of ~-CSEVE.
Thus, there is obtained a white elastic copolymer of
TFE-PPVE-3-CSPVE.
It is found that the copolymer comprises 65.5 %
by mole of TFE, 33.3 % by mole of PPVE and 1.2 % by
mole of 3-CSPVE and that the sulfonyl chloride group
content of the copolymer is 0.75 ~ by weight based on
the total weight of the copolymer.
Application Example
(Cure of copolymers)
Each of the copolymers obtained in Examples 1 to
6 and Comparative Example 1 is separately mixed with
various additives by means of a rubber roll as indicated
in Table below. Then, the obtained compositions are
subjected to press curing andr thenr to post-curing
under the conditions indicated in the same table.
With respect to the obtained cured products, the cur-
ing characteristics of the products are examined using
an oscillating disc rheometer ~ODR) and the mechanical
properties of the products are examined according to
- 30 -
~2~Z~3~
the Japanese Industrial Standards K-6301.
With respec-t to the measurement of the compres-
sion set, the following method is employed. The
composition is shaped into an O-ring having an outer
diameter of 25.4 mm and a thickness of 2.54 mm. The
compressive stress is applied to the O-ring-shaped
specimen in the direction in parallel with the axis of
the O-ring product until the thickness of the O-ring
specimen becomes 0.54 mm. The compression is effected
at 200 C for 70 hours. Then, the compressive stress
is removed and the thickness of the product is
measured. The Compression set l%) is calculated by
the following equation:
2.54-Q1
Compression set (~) = x 100
1~1 is the thickness of the product after the
compressive stress is removed).
The results are shown in Table below.
- 31 -
~2~7~
Table
Comparativ~ Example No. _
Example 1 1 2 3 4 5 6
¦Copolymer 100 100 100 100100 100100
L ¦ SAF C arbOn b1 aCk 10 10 10 20 10 10 10
. ~ 3¦Perhexa-25B~ 1) 4 4 4 4 3 4 4
6 ITriallyl isocyanurate 4 4 4 3 3 3
~¦Lead monooxide 3 3 3 3 3 3 3
_ Minimum viscosity (Kg-cm) 2.5 2.0 1.81.3 1.52.0 1.9
u~ Scorch time (min-) 1.5 1.9 2.0 2.52.0 1.91.9
uu Degree of curing (Kg-cm) 46 24 22 27 17 24 24
3h Optimum curing time (min) 3.5 4.0 4.04.5 4.04.0 4.0
.~ Primary curing 10 min _ ditto ditto Lditt ditto ditto ditto
h ~under N2 stream) 200C lhr, ditto ditto ditto ditto ditto ditto
100 ~ modulus ~Kg/cm2) _ 85 80 25 75 85 82
~u Tensile strength (Kg/cm2) 160 120 120 200110 120 118
u~ I _ _.__ ____
s ~ Elongation (%) 85 135 140430 160135 140
h Compression set 4) not ,
(B method) (%) obtainable 6570 5072 65 68
Note:
1) Trade name of a product containing 40 % of 2,5-dimethyl-2,5-
di(t-butylperoxy)hexane.
2) determined using a osillating disc rheometer manufactured by
Toyo Seiki Co., Ltd., Japan.
3) determined according to Japanese Industrial Standards K-6301.
4) determined using an O-ring specimen having an outer diameter of
25.4 mm and a thickness of 2.54 mm (compressed at 200 C for
70 hours)
5) ~IT carhon black is used.
~ 32 -
~ ~r~de ~ark
7~
The thus obtained elastomers no longer dissolve
in a solvent such as 2,3-dichlorooctabutane in which
the copolymers before curiny can dissolve.
As is apparent from the curing characteristic
determined by the rheometer, an extremely rapid and
large increase in torque is observed with respect to
the fluorine-containing copolymers of the present
invention, suggesting that a crosslinking reaction
proceeds readily and sufficiently with respect to the
fluorine-containing copolymers of the present inven-
tion.
Further, with respect to the mechanical proper-
ties, the cured copolymer obtained by curing the
copolymer of Comparative Example 1 which has a
sulfonyl chloride group content of 3.53 ~ by weight
based on the total weight of the copolymer shows an
elongation as small as 85 %, and cracking of a sample
of the cured copolymer occurs during determination of
compression set so that compression set of the cured
copolymer cannot be determined. On the other hand,
the cured copolymers obtained by curing the copolymers
of Examples 1 to 6 have good mechanical properties.
Example ~
~5 Substantially the same procedures as in Example 5
- 33 -
72~
are repeated except that perfluoro(2-chlorosulfonyl-
ethylallyl ether) (hereinafter referred to as "2-
CSAE") is used instead of 2-CSEVE. Thus, there is
obtained a white elastic copolymer of TFE-PPVE-2-CSAE.
The sulfonyl chloride group content of the obtained
copolymer is 0.8 % by weight based on the total weight
of the copolymer.
The obtained copolymer can be readily crosslinked
as in the cases of Examples 1 to 6, and the resulting
cured copolymer shows mechanical properties and curing
characteristic similar to those of the cured copoly-
mers obtained by curing the copolymers of Examples 1
to 6.
Example 8
Substantially the same procedures as in Example 1
are repeated except that 65 g of 3-CSVE is used
instead of 18 g of 3-CSVE. Thus, there is obtained a
copolymer of TFE-PPVE-3-CSVE having a sulfonyl chlo-
ride group content of 2.3 ~ by weight based on the
total weight of the copolymer.
The obtained copolymer can be readily crosslinked
as in the cases of Examples 1 to 6 and the resulting
cured copolymer shows mechanical properties and curing
- 34 -
~729~
characteristic similar to those of the cured copoly-
mers obtained by curing the copolymers of Examples 1
to 6.
- 35 -
