U.S. patent application number 12/186947 was filed with the patent office on 2009-02-19 for fluorosulfonyl group-containing monomer and its polymer, and sulfonic acid group-containing polymer.
This patent application is currently assigned to ASAHI GLASS COMPANY LIMITED. Invention is credited to Masao IWAYA, Susumu SAITO, Atsushi WATAKABE, Hiromasa YAMAMOTO.
Application Number | 20090048424 12/186947 |
Document ID | / |
Family ID | 40363496 |
Filed Date | 2009-02-19 |
United States Patent
Application |
20090048424 |
Kind Code |
A1 |
WATAKABE; Atsushi ; et
al. |
February 19, 2009 |
FLUOROSULFONYL GROUP-CONTAINING MONOMER AND ITS POLYMER, AND
SULFONIC ACID GROUP-CONTAINING POLYMER
Abstract
To provide a fluorosulfonyl group-containing monomer having a
high polymerization reactivity and plural fluorosulfonyl groups.
Further, to provide a fluorosulfonyl group-containing polymer and a
sulfonic acid group-containing polymer, obtained by using the
monomer. A perfluoro(2-methylene-1,3-dioxolane) derivative which is
represented by the following formula (3) and which has two
fluorosulfonyl groups, and its production process and its synthetic
intermediate. A fluorosulfonyl group-containing polymer having
monomer units represented by the following formula (3U) obtained by
polymerizing the compound (3) by itself or with a comonomer, and a
sulfonic acid group-containing polymer having the following units
(5U) obtained by hydrolyzing a fluorosulfonyl group of the polymer.
In the following formulae, each of R.sup.f1 and R.sup.f2 which are
independent of each other, is a C.sub.1-8 perfluoroalkylene group
which may have an etheric oxygen atom between carbon atoms.
##STR00001##
Inventors: |
WATAKABE; Atsushi;
(Chiyoda-ku, JP) ; YAMAMOTO; Hiromasa;
(Chiyoda-ku, JP) ; IWAYA; Masao; (Chiyoda-ku,
JP) ; SAITO; Susumu; (Chiyoda-ku, JP) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND MAIER & NEUSTADT, P.C.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
ASAHI GLASS COMPANY LIMITED
Chiyoda-ku
JP
|
Family ID: |
40363496 |
Appl. No.: |
12/186947 |
Filed: |
August 6, 2008 |
Current U.S.
Class: |
528/391 ;
549/453; 549/454 |
Current CPC
Class: |
C08G 75/23 20130101;
C07D 317/42 20130101 |
Class at
Publication: |
528/391 ;
549/453; 549/454 |
International
Class: |
C08G 75/20 20060101
C08G075/20; C07D 317/10 20060101 C07D317/10 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 9, 2007 |
JP |
2007-208024 |
Claims
1. A compound represented by the following formula (3):
##STR00025## wherein each of R.sup.f1 and R.sup.f2 which are
independent of each other, is a C.sub.1-8 perfluoroalkylene group
which may have an etheric oxygen atom between carbon atoms.
2. The compound according to claim 1, wherein each of
--R.sup.f1--SO.sub.2F and R.sup.f2--SO.sub.2F is a perfluorinated
2-fluorosulfonyl ethoxy group-substituted alkylene group (the
alkylene group has 1 to 3 carbon atoms).
3. A process for producing a compound represented by the following
formula (3), which comprises heat-decomposing a compound
represented by the following formula (2); ##STR00026## wherein each
of R.sup.f1 and R.sup.f2 which are independent of each other, is a
C.sub.1-8 perfluoroalkylene group which may have an etheric oxygen
atom between carbon atoms.
4. The process according to claim 3, wherein each of
--R.sup.f1--SO.sub.2F and --R.sup.f2--SO.sub.2F is a perfluorinated
2-fluorosulfonyl ethoxy group-substituted alkylene group (the
alkylene group has 1 to 3 carbon atoms).
5. The process according to claim 3, wherein the compound
represented by the above formula (2) is produced from a compound
represented by the following formula (1) through (a) a step of
epoxidation, (b) a step of forming a dioxolane ring and (c) a step
of fluorination; ##STR00027## wherein each of R.sup.1 and R.sup.2
which are independent of each other, is a C.sub.1-8 alkylene group
which may have an etheric oxygen atom between carbon atoms and of
which some or all of hydrogen atoms may be substituted by fluorine
atoms.
6. The process according to claim 5, wherein each of
--R.sup.1--SO.sub.2F and --R.sup.2--SO.sub.2F is a
2-fluorosulfonyl-tetrafluoroethoxy group-substituted alkylene group
(the alkylene group has 1 to 3 carbon atoms).
7. A compound represented by the following formula (2):
##STR00028## wherein each of R.sup.f1 and R.sup.f2 which are
independent of each other, is a C.sub.1-8 perfluoroalkylene group
which may have an etheric oxygen atom between carbon atoms.
8. The compound according to claim 7, wherein each of
--R.sup.f1--SO.sub.2F and R.sup.f2--SO.sub.2F is a perfluorinated
2-fluorosulfonyl ethoxy group-substituted alkylene group (the
alkylene group has 1 to 3 carbon atoms).
9. A process for producing a fluorosulfonyl group-containing
polymer, which comprises polymerizing at least one compound
represented by the following formula (3), or at least one such a
compound and at least one polymerizable monomer copolymerizable
with such a compound: ##STR00029## wherein each of R.sup.f1 and
R.sup.f2 which are independent of each other, is a C.sub.1-8
perfluoroalkylene group which may have an etheric oxygen atom
between carbon atoms.
10. A fluorosulfonyl group-containing polymer comprising at least
one type of monomer units represented by the following formula
(3U), or at least one type of such monomer units and at least one
type of other monomer units: ##STR00030## wherein each of R.sup.f1
and R.sup.f2 which are independent of each other, is a C.sub.1-8
perfluoroalkylene group which may have an etheric oxygen atom
between carbon atoms.
11. The fluorosulfonyl group-containing polymer according to claim
10, which has a molecular weight of from 5.times.10.sup.3 to
5.times.10.sup.6, and which, when containing said other monomer
units, contains from 0.1 to 99.9 mol % of monomer units represented
by the formula (3U).
12. A process for producing a polymer containing sulfonate groups
or sulfonic acid groups, which comprises subjecting the
fluorosulfonyl group in the fluorosulfonyl group-containing polymer
according to claim 10 to an alkali hydrolysis, or to such an alkali
hydrolysis, followed by an acid treatment.
13. A sulfonic acid group-containing polymer containing at least
one type of units represented by the following formula (5U), or at
least one type of such units and at least one type of other units;
##STR00031## wherein each of R.sup.f1 and R.sup.f2 which are
independent of each other, is a C.sub.1-8 perfluoroalkylene group
which may have an etheric oxygen atom between carbon atoms.
14. The sulfonic acid group-containing polymer according to claim
13, which has a molecular weight of from 5.times.10.sup.3 to
5.times.10.sup.6, and which, when containing other units, contains
from 0.1 to 99.9 mol % of units represented by the formula
(5U).
15. An electrolyte material for polymer electrolyte fuel cells,
which comprises the sulfonic acid group-containing polymer
according to claim 13.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a fluorosulfonyl
group-containing polymer which is a precursor of a sulfonic acid
group-containing polymer useful as an ion-exchange membrane (e.g. a
membrane to be used for brine electrolysis or polymer electrolyte
fuel cells) or an electrolyte membrane to be used for a catalyst
layer of a fuel cell; and a new fluorosulfonyl group-containing
monomer which can be a raw material of the polymer. Further, the
present invention relates to a process for producing the
fluorosulfonyl group-containing monomer and a new compound useful
as an intermediate for production of the monomer. Furthermore, it
relates to a sulfonic acid group-containing polymer obtainable from
the above fluorosulfonyl group-containing polymer and an
electrolyte material for polymer electrolyte fuel cells, which
comprises the sulfonic acid group-containing polymer.
[0003] 2. Discussion of Background
[0004] Heretofore, a copolymer of a fluorinated monomer of the
following formula and tetrafluoroethylene, has been used as a
membrane for brine electrolysis, a membrane of a polymer
electrolyte fuel cell or its catalyst layer. In the following
formula, Y is a fluorine atom or a trifluoromethyl group, n is an
integer of from 1 to 12, m is an integer of from 0 to 3, k is 0 or
1, and m+k>0;
CF.sub.2--CF--(OCF.sub.2CFY).sub.m--O.sub.k--(CF.sub.2).sub.n--SO.sub.2F
[0005] Further, the fluorosulfonyl group (--SO.sub.2F) in the
copolymer can be converted to a sulfonic acid group (--SO.sub.3H)
by alkali hydrolysis, followed by acid treatment.
[0006] When used for a brine electrolysis cell as a membrane having
a high ion-exchange capacity, such a sulfonic acid group-containing
polymer (hereinafter referred to as the sulfonic acid polymer) is a
polymer which can reduce the power for the electrolysis. When the
sulfonic acid polymer is used for a fuel cell, the polymer can
improve the power generation energy efficiency. Further, the
sulfonic acid polymer is preferably a polymer having a higher
ion-exchange capacity and a lower electric resistance.
[0007] However, if the proportion of the fluorosulfonyl
group-containing monomer to be used for copolymerization, is
increased for a purpose of increasing the ion-exchange capacity of
the sulfonic acid polymer, there has been a problem such that the
molecular weight of the copolymer becomes low. A membrane formed by
the copolymer having low molecular weight is insufficient in
mechanical strength and durability, and thus it is not practically
useful. It has been proposed to use a fluorosulfonyl
group-containing monomer having plural fluorosulfonyl groups as a
means to increase the ion-exchange capacity of the sulfonic acid
polymer without increasing the proportion of the fluorosulfonyl
group-containing monomer (Patent Document 1).
[0008] Further, in order to obtain a sulfonic acid polymer having a
high molecular weight, the fluorosulfonyl group-containing monomer
is required to have high copolymerizability with other
fluoromonomers such as tetrafluoroethylene, but the conventional
fluorosulfonyl as group-containing monomer did not sufficiently
have such copolymerizability. As a fluorosulfonyl group-containing
monomer having a high polymerization reactivity, a
perfluoro(2-methylene-1,3-dioxolane) derivative having a
fluorosulfonyl group is known (Patent Documents 2, 3 and 4).
However, such a derivative having plural fluorosulfonyl groups is
not known.
[0009] Patent Document 1: WO2007/013532
[0010] Patent Document 2; WO03/037885
[0011] Patent Document 3: JP-A-2005-314388
[0012] Patent Document 4: JP-A-2006-290864
SUMMARY OF THE INVENTION
[0013] The present invention has an object to provide an
electrolyte material for polymer electrolyte fuel cells, which is
an electrolyte material having a high ion-exchange capacity and low
resistance, and which has a higher softening point than a commonly
used electrolyte material and is excellent in durability. Further,
the present invention has an object to provide a new monomer and a
polymer to prepare such a material.
[0014] The present invention provides a fluorosulfonyl
group-containing monomer having a high polymerization reactivity
and plural fluorosulfonyl groups. The
perfluoro(2-methylene-1,3-dioxolane) derivative having two
fluorosulfonyl groups of the present invention is a new
monomer.
[0015] The present invention is the following invention, which
relates to a fluorosulfonyl group-containing perfluoromonomer
having two fluorosulfonyl groups and a high polymerization
reactivity; its production process and its synthetic intermediate;
a fluorosulfonyl group-containing polymer obtained by polymerizing
the perfluoromonomer; a process for producing a sulfonic acid
polymer from the polymer; and the sulfonic acid polymer and an
electrolyte material for polymer electrolyte fuel cells, which
comprises the sulfonic acid polymer.
(1) A compound represented by the following formula (3):
##STR00002##
wherein each of R.sup.f1 and R.sup.f2 which are independent of each
other, is a C.sub.1-8 perfluoroalkylene group which may have an
etheric oxygen atom between carbon atoms. (2) The compound
according to the above (1), wherein each of --R.sup.f1--SO.sub.2F
and R.sup.f2--SO.sub.2F is a perfluorinated 2-fluorosulfonyl ethoxy
group-substituted alkylene group (the alkylene group has 1 to 3
carbon atoms). (3) A process for producing a compound represented
by the following formula (3) which comprises heat-decomposing a
compound represented by the following formula (2);
##STR00003##
wherein each of R.sup.f3 and R.sup.f2 which are independent of each
other, is a C.sub.2-8 perfluoroalkylene group which may have an
etheric oxygen atom between carbon atoms. (4) The process according
to the above (3), wherein each of --R.sup.f1--SO.sub.2F and
--R.sup.f2--SO.sub.2F is a perfluorinated 2-fluorosulfonyl ethoxy
group-substituted alkylene group (the alkylene group has 1 to 3
carbon atoms). (5) The process according to the above (3) or (4),
wherein the compound represented by the above formula (2) is
produced from a compound represented by the following formula (1)
through (a) a step of epoxidation, (b) a step of forming a
dioxolane ring and (c) a step of fluorination:
##STR00004##
wherein each of R.sup.1 and R.sup.2 which are independent of each
other, is a C.sub.1-8 alkylene group which may have an etheric
oxygen atom between carbon atoms and of which some or all of
hydrogen atoms may be substituted by fluorine atoms. (6) The
process according to the above (5), wherein each of
--R.sup.2--SO.sub.2F and --R.sup.2--SO.sub.2F is a
2-fluorosulfonyl-tetrafluoroethoxy group-substituted alkylene group
(the alkylene group has 1 to 3 carbon atoms). (7) A compound
represented by the following formula (2):
##STR00005##
wherein each of R.sup.f1 and R.sup.f2 which are independent of each
other, is a C.sub.1-8 perfluoroalkylene group which may have an
etheric oxygen atom between carbon atoms. (8) The compound
according to the above (7), wherein each of --R.sup.f1--SO.sub.2F
and --R.sup.f2--SO.sub.2F is a perfluorinated 2-fluorosulfonyl
ethoxy group-substituted alkylene group (the alkylene group has 1
to 3 carbon atoms). (9) A process for producing a fluorosulfonyl
group-containing polymer, which comprises polymerizing at least one
compound represented by the following formula (3), or at least one
such a compound and at least one polymerizable monomer
copolymerizable with such a compound:
##STR00006##
wherein each of R.sup.f1 and R.sup.f2 which are independent of each
other, is a C.sub.1-8 perfluoroalkylene group which may have an
etheric oxygen atom between carbon atoms. (10) A fluorosulfonyl
group-containing polymer comprising at least one type of monomer
units represented by the following formula (3U), or at least one
type of such monomer units and at least one type of other monomer
units;
##STR00007##
wherein each of R.sup.f1 and R.sup.f2 which are independent of each
other, is a C.sub.1-8 perfluoroalkylene group which may have an
etheric oxygen atom between carbon atoms. (11) The fluorosulfonyl
group-containing polymer according to the above (10), which has a
molecular weight of from 5.times.10.sup.3 to 5.times.10.sup.6, and
which, when containing said other monomer units, contains from 0.1
to 99.9 mol % of monomer units represented by the formula (3U).
(12) A process for producing a polymer containing sulfonate groups
or sulfonic acid groups, which comprises subjecting the
fluorosulfonyl group in the fluorosulfonyl group-containing polymer
according to the above (10) or (11) to an alkali hydrolysis, or to
such an alkali hydrolysis, followed by an acid treatment. (13) A
sulfonic acid group-containing polymer containing at least one type
of units represented by the following formula (5U), or at least one
type of such units and at least one type of other units:
##STR00008##
wherein each of R.sup.f1 and R.sup.f2 which are independent of each
other, is a C.sub.1-8 perfluoroalkylene group which may have an
etheric oxygen atom between carbon atoms. (14) The sulfonic acid
group-containing polymer according to the above (13), which has a
molecular weight of from 5.times.10.sup.3 to 5.times.10.sup.6, and
which, when containing other units, contains from 0.1 to 99.9 mol %
of units represented by the formula (5U). (15) An electrolyte
material for polymer electrolyte fuel cells, which comprises the
sulfonic acid group-containing polymer according to the above (13)
or (14).
[0016] The monomer of the present invention is a perfluoromonomer
having a perfluoro(2-methylene-1,3-dioxolane) structure having a
high polymerization reactivity and two fluorosulfonyl groups,
whereby it is easy to obtain a copolymer having a high molecular
weight by copolymerizing it with a copolymerizable monomer such as
tetrafluoroethylene, and it is easy to obtain a sulfonic acid
polymer having high mechanical strength and durability. Further,
since the monomer of the present is invention has two
fluorosulfonyl groups, it is possible to obtain a sulfonic acid
polymer having a high ion-exchange capacity even if its
copolymerization ratio is low, as compared with a monomer having
one fluorosulfonyl group.
[0017] The sulfonic acid polymer of the present invention is useful
as an electrolyte material for polymer electrolyte fuel cells since
it has a low electric resistance owing to its high ion-exchange
capacity; has a high softening point and excellent mechanical
strength; and further has durability. Since the electrolyte
material has a high softening point, it is possible to operate a
cell at a higher temperature than conventional ones, and it is
possible to make the fuel cell have a high output or improve the
cooling efficiency.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0018] In the present specification, a compound represented by the
formula (3) is shown as a compound (3). Further, a group
represented by the formula (3a) is shown as a group (3a), and units
represented by the formula (3U) are shown as units (3U). A polymer
containing units (3U) is shown as a polymer (3U). The same applies
to compounds, groups, units or polymers represented by other
formulae.
[0019] Units in a polymer mean units derived from a monomer as
formed by polymerization of the monomer, and the units in the
present invention may be units directly formed is from a
polymerization reaction or units formed by a chemical conversion
after the polymerization reaction. Among such units, the units
maintaining the monomer structure except for the unsaturated groups
which transform by polymerization reaction of the monomer, are
referred to as monomer units.
[0020] Hereinafter, a fluorosulfonyl group may also be shown as a
--SO.sub.2F group, a fluorocarbonyl group as a --COF group and a
sulfonic acid group as a --SO.sub.3H group.
[0021] The present invention provides the following compound
(3).
##STR00009##
[0022] In the compound (3), each of R.sup.f1 and R.sup.f2 which are
independent of each other, is a C.sub.1-8 perfluoroalkylene group
which may have an etheric oxygen atom between carbon atoms. Number
of carbon atoms in each perfluoroalkylene group is more preferably
from 1 to 6, particularly preferably from 2 to 5. Further, when the
number of carbon atoms in each perfluoroalkylene group is at least
2, an etheric oxygen atom may be contained between the carbon
atoms, and the number of the etheric oxygen atoms is preferably 1
or 2, particularly preferably 1. Further, each perfluoroalkylene
group is preferably linear or branched to have at most two
trifluoromethyl groups, particularly preferably linear. Moreover,
R.sup.f1 and R.sup.f2 are preferably the same groups, but not so
restricted. For example, R.sup.f1 and R.sup.f2 may be
perfluoroalkylene groups different in number of carbon atoms, and
may be perfluoroalkylene groups such that one has an etheric oxygen
atom, and the other has no etheric oxygen atom.
[0023] Each of --R.sup.f1--SO.sub.2F and --R.sup.f2--SO.sub.2F in
the compound (3) is preferably a group represented by the following
formula (s-1). In the formula, p is an integer of at least 1, q is
an integer of at least 1, p+q is from 2 to 5, and r is 0 or 1. The
group (s-1) preferably has p of from 1 to 3, q of 2 and r of 1,
namely preferably is a perfluorinated 2-fluorosulfonyl ethoxy
group-substituted alkylene group (the alkylene group has 1 to 3
carbon atoms).
--(CF.sub.2).sub.p--(O).sub.r--(CF.sub.2).sub.q--SO.sub.2F
(s-1)
[0024] Specific examples of the compound (3) are the following
compounds:
##STR00010##
[0025] The compound (3) of the present invention can be produced by
heat-decomposing the following compound (2). R.sup.f1 and R.sup.f2
in the compound (2) corresponding to R.sup.f1 and R.sup.f2 in the
compound (3), are C.sub.1-8 perfluoroalkylene groups which may have
an etheric oxygen atom between carbon atoms. Further, the compound
(2) is a new compound.
##STR00011##
[0026] The heat-decomposition of the compound (2) may be carried
out in accordance with a method described in the above Patent
Document 2, 3 or 4 such that by heat-decomposing a 1,3-dioxolane
derivative having a --COF group and a trifluoromethyl group at the
2-position, a 1,3-dioxolane derivative having a difluoromethylene
(.dbd.CF.sub.2) group at the 2-position is produced. A summary of
the heat-decomposition of the compound (2) is described as
follows.
[0027] The heat-decomposition reaction can be carried out by a gas
phase reaction or a liquid phase reaction, and it is preferably
carried out by a gas phase reaction from the viewpoint of
efficiency. Further, the method for the heat-decomposition reaction
and the reaction temperature are preferably selected depending on
the boiling point or stability of the compound (2). Further, the
compound (2) preferably has a boiling point of at most 350.degree.
C. for such a reason that the heat-decomposition reaction can
thereby be carried out efficiently by a gas phase reaction.
Moreover, the gas phase reaction is preferably carried out in the
presence of glass beads, an alkali metal salt or an alkaline earth
metal salt.
[0028] The gas phase reaction is preferably carried out by a
continuous reaction. The continuous reaction is preferably carried
out by a process such that a vaporized compound (2) is let flow in
a heated reaction tube, and a formed compound (3) is obtained as an
outlet gas, followed by condensation to recover it continuously.
When the heat-decomposition is carried out by a gas phase reaction,
the reaction temperature is preferably at least 150.degree. C.,
particularly preferably from 200.degree. C. to 500.degree. C.,
especially preferably from 250.degree. C. to 450.degree. C. If the
reaction temperature is too high, the yield tends to be low by a
decomposition reaction of the product. Further, when the
heat-decomposition reaction is carried out by a gas phase reaction,
it is preferred to use a tube-type reactor. When the tube-type
reactor is used, the retention time is preferably approximately
from 0.1 second to 10 minutes based on a void tower standard. The
reaction pressure is not particularly limited.
[0029] When the gas phase reaction is carried out by using the
tube-type reactor, the reaction tube is preferably packed with
glass, an alkali metal salt or an alkaline earth metal salt, for a
purpose of accelerating the reaction. The alkali metal salt or the
alkaline earth metal salt is preferably a carbonate or a fluoride.
The glass may be common soda glass, and particularly preferably
glass bead having increased mobility.
[0030] With respect to the gas phase reaction, for a purpose of
accelerating the vaporization of the compound (2), the reaction is
preferably carried out in the presence of an inert gas which does
not get directly involved in the heat-decomposition reaction. The
inert gas may, for example, be nitrogen, carbon dioxide, helium or
argon. The concentration of the compound (2) in the inert gas is
preferably approximately from 0.01 to 50 volt.
[0031] The heat-decomposition reaction can also be carried out
after the compound (2) is converted to alkali metal or alkaline
earth metal salt of the corresponding carboxylic acid. In such a
method, the compound (2) is led to alkali metal or alkaline earth
metal salt of the corresponding carboxylic acid in the presence of
a solvent, by a reaction with a carbonate or a hydrogen carbonate
of alkali metal or alkaline earth metal, followed by removal of the
solvent. In such a method, it is possible to selectively lead a
--COF group to a salt of carboxylic acid without hydrolyzing a
--SO.sub.2F group in the compound (2). The solvent may be a
nonpolar solvent or a polar solvent, and it is preferably a polar
solvent since the reaction can thereby be carried out at a low
temperature. The heat-decomposition temperature of an alkali metal
salt of the compound (2) is preferably from 100 to 300.degree. C.,
particularly preferably from 150 to 250.degree. C. The
heat-decomposition reaction via an alkali metal salt is preferred
since it can be carried out at a low temperature as compared with a
heat-decomposition method in a gas phase.
[0032] The compound (2) can be produced in accordance with a method
described in the above Patent Document 2, 3 or 4. Such documents
describe a process for producing a 1,3-dioxolane derivative (having
one --SO.sub.2F group) having a --COF group and a trifluoromethyl
group at the 2-position from a starting material of a monoene
having one --SO.sub.2F group via a step of epoxidation and a step
of forming a 1,3-dioxolane ring. Further, in a case where the
1,3-dioxolane derivative obtained in the above step of forming a
1,3-dioxolane ring, has hydrogen atoms, the derivative is
subsequently fluorinated to obtain a perfluorinated 1,3-dioxolane
derivative which is then converted to a 1,3-dioxolane derivative
(having one --SO.sub.2F group) having a --COF group and a
trifluoromethyl group at the 2-position. In the present invention,
the compound (2) can be produced in the same manner from a starting
material of a monoene having two --SO.sub.2F groups.
[0033] The compound (2) is preferably produced from the compound
(1) represented by the following formula via (a) a step of
epoxidation, (b) a step of forming a dioxolane ring and (c) a step
of fluorination. Now, such preferred process steps will be
described. However, a process for producing the compound (2) is by
no means restricted thereto. For example, a starting material of a
perfluorinated compound corresponding to the compound (a compound
wherein all hydrogen atoms in the compound (1) are fluorine atoms)
may be converted to a diketone through an epoxidation of an
unsaturated group portion, followed by a reaction with
hexafluoropropylene oxide to obtain a 1,4-dioxane ring compound in
accordance with a method disclosed in Patent Document 4. It is
possible to produce the compound (2) by heat-decomposing the
obtained 1,4-dioxane ring compound. Such a process does not require
a step of fluorination.
##STR00012##
[0034] In the above formula (1), each of R.sup.1 and R.sup.2 which
are independent of each other, is a C.sub.1-8 alkylene group which
may have an etheric oxygen atom between carbon atoms and of which
some or all of hydrogen atoms may be substituted by fluorine atoms.
Further, the compound (1) may be a trans-form or a cis-form. Each
of such R.sup.1 and R.sup.2 is a group corresponding to the above
R.sup.f1 or R.sup.f2, namely, it is the same group as the above
R.sup.f1 or R.sup.f2, or a group to be converted to the above
R.sup.f1 or R.sup.f2 by fluorination. In the latter case, it is
preferably a group having the same structure as the above R.sup.f1
or R.sup.f2 except that some or all of fluorine atoms in the above
R.sup.f1 or R.sup.f2 are substituted by hydrogen atoms, and
particularly preferably a group having both hydrogen atoms and
fluorine atoms. The proportion of the number of the hydrogen atoms
based on the total of hydrogen atoms and fluorine atoms in each of
R.sup.1 and R.sup.2 is from 30 to 100%, particularly preferably
from 30 to 70%. Further, since R.sup.1 and R.sup.2 are groups
corresponding to the above R.sup.f1 and R.sup.f2, the preferred
number of carbon atoms, number of etheric oxygen atoms or structure
such as a linear structure, of R.sup.1 and R.sup.2 are the same as
the above R.sup.f1 and R.sup.f2.
[0035] Each of --R.sup.1--SO.sub.2F and --R.sup.2--SO.sub.2F in the
compound (1) is preferably a group represented by the following
formula (s-2). In the following formula (s-2), X represents a
hydrogen atom or a fluorine atom, and each X in the formula may be
different. Since R.sup.1 and R.sup.2 are groups corresponding to
the above R.sup.f1 and R.sup.f2, p, q and r are the same as the
above group (s-1). The more preferred group represented by the
following formula (s-2) is a 2-fluorosulfonyl ethoxy
group-substituted alkylene group represented by the following
formula (s-3) (in the formula (s-3), p is from 1 to 3).
--(CX.sub.2).sub.p--(O).sub.r--(CX.sub.2).sub.q--SO.sub.2F
(s-2)
--(CH.sub.2).sub.p--O--(CF.sub.2).sub.2--SO.sub.2F (s-3)
[0036] An embodiment of scheme for producing the compound (2) from
the compound (1) represented by the following formula via (a) a
step of epoxidation, (b) a step of forming a dioxolane ring and (c)
a step of fluorination, is shown as follows. Here, the following
compound (1) may be a cis-form or a trans-form, and the compound
(1) used in Examples given hereinafter was a transform.
##STR00013##
[0037] In the above formula (13), R.sup.3 represents an alkyl group
or a polyfluoroalkyl group which may contain an etheric oxygen atom
between carbon atoms. The number of carbon atoms in R.sup.3 is
properly from 1 to 20, preferably 3 to 12. R.sup.3 is particularly
preferably a C.sub.3-10 perfluoroalkyl group or an etheric oxygen
atom-containing perfluoroalkyl group having 3 to 12 carbon atoms
and 1 to 3 etheric oxygen atoms. R.sup.3' in the above formula (14)
is a group (a perfluorinated group) of which the hydrogen atoms are
all substituted by fluorine atoms, provided that when R.sup.3 is a
group containing hydrogen atoms, or the 3, same group as R.sup.3
when R.sup.3 is a group (a perfluorinated group) not containing
hydrogen atoms. As R.sup.3 (the same for R.sup.3'), the following
perfluorinated group is particularly preferred:
[0038] --CF.sub.2CF.sub.2CF.sub.3, --CF (CF.sub.3).sub.2,
--CF(CF.sub.3)CF.sub.2CF.sub.3, --CF(CF.sub.3)O(CF.sub.2).sub.3F or
--CF(CF.sub.3)OCF.sub.2CF(CF.sub.3)O(CF.sub.2).sub.3F.
[0039] (a) A step of epoxidation in the present invention is a step
of producing a compound (11) from the compound (1) in the above
scheme, and it includes an epoxidation reaction [a]. (b) A step of
forming a dioxolane ring is a step of producing a compound (13)
from the compound (11) in the above scheme, and it includes a
reaction [b-1] of forming a dioxolane ring. The compound (13) is
preferably produced by a reaction [b-2] of converting a side chain
group via a compound (12), but it may be produced directly from the
compound (11). The reaction [b-2] of converting a side chain group
is preferably a ketal exchange reaction. It is preferred to produce
the compound (13) from the compound (11) by carrying out the
reaction [b-1] and the reaction [b-2] without isolating the
compound (12). (c) A step of fluorination is a step of producing
the compound (2) from the compound (13) in the above scheme, and it
includes a fluorination reaction [c-1]. The compound (2) is
preferably produced by an ester-decomposition reaction [c-2] via a
compound (14), but the compound (2) may sometimes be obtained from
the compound (13) when the ester-decomposition reaction [c-2]
proceeds simultaneously with the fluorination reaction [c-1]. It is
preferred to carry out the fluorination reaction [c-1] and the
ester-decomposition reaction [c-2] separately.
[0040] In (a) a step of epoxidation, the compound (11) is obtained
by oxidizing the compound (1) with an oxidizing agent. As the
oxidizing agent, it is possible to use oxygen gas, a hypochlorite
or a peroxide. The peroxide may, for example, be m-chloroperbenzoic
acid, perbenzoic acid, peracetic acid or hydrogen peroxide. The
epoxidation of an unsaturated group by using such an oxidizing
agent may be carried out by a known method.
[0041] In (b) a step of forming a dioxolane ring, the compound (12)
is synthesized by reacting the compound (11) with acetone. At that
time, instead of directly reacting the compound (11) with acetone,
it is possible to react water with the compound (11) to obtain a
diol, and then react such a diol with acetone to synthesize the
compound (12). Such a reaction is preferably carried out in the
presence of an acid catalyst. The acid catalyst may, for example,
be an inorganic acid, a Lewis acid or a solid acid. Then, the
compound (12) is reacted (reaction [b-2]) with hydroxyacetone ester
represented by the following formula (15) to produce the compound
(13). The reaction [b-2] is a ketal exchange reaction, wherein an
acetone residue is converted to a hydroxyacetone ester (15)
residue. Further, the compound (13) may also be produced in such a
manner that the compound (12) is subjected to a ketal exchange
reaction with a hydroxyacetone to convert an acetone residue to a
hydroxyacetone residue, and then its hydroxyl group is converted to
a R.sup.3COO-- group. With respect to such a ketal exchange
reaction, it is preferably carried out, in the presence of the
above acid catalyst, by removing acetone which forms as a byproduct
in a high boiling point solvent, from the reaction system. Further,
it is possible to sequentially carry out the reaction [b-1] and
reaction [b-2] by changing the reaction condition while the
compound (11), acetone and the compound (15) are permitted to
coexist. Further, it is also possible to obtain the compound (13)
by reacting the compound (11) or its diol compound with
hydroxyacetone ester (15).
##STR00014##
[0042] In (c) a step of fluorination, first, all hydrogen atoms in
the compound (13) are substituted by fluorine atoms by a
fluorination reaction [c-1] to obtain the compound (14). A method
for the fluorination reaction may, for example, be a method for a
reaction with fluorine in a gas phase, or a method for a
fluorination reaction carried out in a liquid phase such as an
electro-chemical fluorination method (ECF method) or a cobalt
fluorination method. From the viewpoint of handling efficiency and
the yield of the reaction, the fluorination carried out in a liquid
phase is a particularly advantageous method, and a method of
reacting the compound (13) with fluorine (F.sub.2) in a liquid
phase (namely, a method so-called a liquid phase fluorination) is
particularly preferred. Details of the liquid phase fluorination
are described not only in the above Patent Document 2, but also in
WO00/056694, etc.
[0043] In the liquid phase fluorination, as fluorine, it is
possible to use fluorine gas as it is or fluorine gas diluted by an
inert gas such as nitrogen gas. The amount of fluorine in an inert
gas is preferably at least 10 volt, particularly preferably at
least 20 volt.
[0044] In the liquid phase fluorination, a solvent is usually used
in order to form a liquid phase. The solvent is preferably a
solvent which does not contain a C--H bond and essentially contains
a C--F bond, or a fluorinated solvent having at least one atom
selected from a group consisting of a chlorine atom, a nitrogen
atom or an oxygen atom, in the structure and containing no C--H
bond (hereinafter such a fluorine type solvent including a
perfluoroalkane is referred to as a perfluoro-solvent). The solvent
may be a solvent inactive in the fluorination reaction, and it may
have a functional group active in other reactions. For example, it
is possible to use, as a solvent, a perfluoroether or a
perfluoroalkane having a fluorocarbonyl group (--COF group).
Further, as the solvent, it is preferred to use a solvent
presenting a high solubility for the compound (13). Especially, it
is preferred to use a solvent which can dissolve at least 1 mass %
of the compound (13), particularly preferred to use a solvent which
can dissolve at least 5 mass %. Further, the amount of the solvent
is preferably at least 5 times by mass, particularly preferably
from 10 to 100 times by mass, based on the compound (13).
[0045] The reaction style of the liquid phase fluorination reaction
may be a batch system or a continuous system. Particularly, it is
preferred to carry out the fluorination in such a manner that a
solvent is charged in a reactor, and stirring is started, and after
the reaction temperature and the reaction pressure are controlled
at prescribed levels, the fluorine gas and the compound (13) are
continuously and simultaneously supplied in a prescribed molar
ratio.
[0046] The amount of fluorine to be used for the liquid phase
fluorination is preferably constantly in excess by equivalent
relative to hydrogen atoms to be fluorinated, particularly
preferably at least 1.5 times by equivalent (namely, at least 1.5
mol) from the viewpoint of selectivity, when the reaction is
carried out either by a batch system or a continuous system.
Further, the amount of fluorine is preferably kept to be constantly
in excess by equivalent from the beginning of the reaction to the
end of the reaction.
[0047] The reaction temperature for the liquid phase fluorination
is usually preferably at least -60.degree. C. and at most the
boiling point of the compound (13), particularly preferably from
-50.degree. C. to +100.degree. C. from the viewpoint of the
reaction yield, selectivity and industrial operation efficiency,
particularly preferably from -20.degree. C. to +50.degree. C. The
reaction pressure for the liquid phase fluorination is not
particularly limited, and it is particularly preferably from a
normal pressure to 2 MPa from the viewpoint of the reaction yield,
selectivity and industrial operation efficiency.
[0048] Further, in order to let the liquid phase fluorination
efficiently proceed, it is preferred to add a C--H bond-containing
compound in the reaction system at a late stage of the reaction or
to carry out ultraviolet irradiation. By using the C--H
bond-containing compound, it is possible to efficiently fluorinate
the compound (13) present in the reaction system, and it is
possible to improve the reaction rate significantly. The C--H
bond-containing compound is an organic compound other than the
compound (13), and specifically, it is preferably an aromatic
hydrocarbon, particularly preferably benzene or toluene. The amount
of the C--H bond-containing compound to be added is preferably from
0.1 to 10 mol %, particularly preferably from 0.1 to 5 mol %, based
on hydrogen atoms in the compound (13).
[0049] HF which forms as a byproduct in the liquid phase
fluorination is removed by an HF capture agent such as NaF, and the
product and the solvent are separated to obtain the compound (14)
as a product. The compound (14) obtained by the fluorination may be
subjected to an ester-decomposition reaction [c-2] as it is in the
form of a crude product, or may be subjected to an
ester-decomposition reaction [c-2] after purification.
[0050] The ester-decomposition reaction [c-2] of the compound (14)
is preferably carried out by a decomposition reaction by heat or a
decomposition reaction to be carried out in a liquid phase in the
presence of a nucleophilic agent or an electrophile.
[0051] The decomposition reaction by heat can be carried out by
heating the compound (14). The reaction temperature of the gas
phase heat-decomposition reaction is preferably from 50 to
350.degree. C., particularly preferably from 50 to 300.degree. C.,
particularly preferably from 150 to 250.degree. C. Further, it is
permitted to let coexist an inert gas such as nitrogen which does
not get directly involved with the reaction, in the reaction
system. It is preferred to add the inert gas approximately from
0.01 to 50 vol % based on the compound (14). If the amount of the
inert gas to be added is large, the recovered amount of the product
may sometimes be lowered.
[0052] It is also possible to use a liquid phase heat-decomposition
reaction which heats up the compound (14) in a liquid state in the
reactor. In such a case, the reaction pressure is not limited. In a
usual case, since the product containing the compound (2) has a
lower boiling point than the compound (14), the product is
preferably obtained by a method of a reaction distillation system
wherein the product is vaporized and continuously withdrawn.
Further, it may be obtained by a method wherein after the
completion of heating, the product is withdrawn from the reactor
all at once. The reaction temperature of such a liquid phase
heat-decomposition reaction is preferably from 50 to 300.degree.
C., particularly preferably from 100 to 250.degree. C.
[0053] The liquid phase heat-decomposition reaction may be carried
out in the presence or absence of a solvent. The solvent is not
particularly limited as long as it is one which does not react with
the compound (14), has a compatibility with the compound (14) and
does not react with the compound (2) to be formed. Further, as the
solvent, it is preferred to select one easily separable at the time
of purification of the compound (2). Specific examples of the
solvent may be a perfluorinated solvent such as
perfluorotrialkylamine or perfluorodecaline, and a fluorinated
inactive solvent such as chlorotrifluoroethylene oligomer. Further,
the amount of the solvent is preferably from 10 to 1,000 mass %
based on the compound (14).
[0054] Further, the compound (14) can be subjected to an
ester-decomposition by a reaction with a nucleophilic agent or an
electrophile in a liquid phase in the absence of a solvent or in
the presence of the above fluorinated inactive solvent.
Particularly, it is preferred that the compound is subjected to the
ester-decomposition by a reaction with the nucleophilic agent. The
nucleophilic agent is preferably F.sup.-, particularly preferably
F.sup.- derived from a fluoride of an alkali metal. The fluoride of
an alkali metal is preferably NaF, NaHF.sub.2, KF or CsF. Among
them, NaF is particularly preferred from the viewpoint of economic
efficiency, and KF is particularly preferred from the viewpoint
that the reaction can be carried out at a low reaction temperature.
When the nucleophilic agent (e.g. F.sup.-) is used, the
nucleophilic agent used at the beginning of the reaction may be in
a is catalytic amount and may be used excessively. That is, the
amount of the nucleophilic agent such as F.sup.- is preferably from
1 to 500 mol %, particularly preferably from 1 to 100 mol %,
especially preferably from 5 to 50 mol %, based on the compound
(14). The reaction temperature is preferably from -30.degree. C. to
the boiling point of the solvent or the compound (14), particularly
preferably from -20.degree. C. to 250.degree. C. This method is
also preferably carried out by a reaction distillation system.
[0055] The compound (1) as a starting material in the above process
can be produced by a known method or in accordance with a known
method. For example, in the above Patent Document 2, it is
disclosed that an alkenyl compound having a --SO.sub.2F group is
obtained by reacting a bromoalkene with
tetrafluoroethane-1,2-sulfone (hereinafter referred to simply as
sulfone). Accordingly, it is possible to obtain a compound (1) as
an unsaturated compound having two --SO.sub.2F groups by reacting
dibromoalkene with sulfone. Further, the above Patent Document 3
discloses a process to obtain an alkenyl compound having a
--SO.sub.2F group from an alkenyl alcohol via an alkenyl compound
having a --SO.sub.2(OZ) group (Z: alkali metal). Accordingly, it is
possible to obtain a compound (1) as an unsaturated compound having
two --SO.sub.2F groups from an alkenediol via an unsaturated
compound having two --SO.sub.2 (OZ) groups (Z: alkali metal). A
specific example of such a method may be a method to obtain a
compound (1) having a group (s-3) represented by the following
formula (1a) by a reaction of a compound represented by the
following formula (10a) with sulfone represented by the formula
(10b). Further, as mentioned above, the compound (10a) or the
compound (1a) may be a cis-form or a trans-form, and in the
Examples given hereinafter, the trans-form is used.
##STR00015##
[0056] The present invention is a fluorosulfonyl group-containing
polymer comprising at least one type of monomer units represented
by the following formula (3U) or at least one type of such monomer
units and at least one type of other monomer units. The monomer
units (3U) are monomer units formed by polymerization of the
compound (3). R.sup.f1 and R.sup.f2 in the monomer unit (3U) are
the same as R.sup.f1 and R.sup.f2 in the compound (3).
##STR00016##
[0057] The polymer having the monomer units (3U) (namely, a polymer
(3U)) is useful as a precursor of an electrolyte material to be
used for an application to a brine electrolysis or a fuel cell. For
example, a fluorosulfonyl group-containing polymer as a homopolymer
or copolymer of the compound (3) is useful as a precursor of a
sulfonic acid polymer having a high molecular weight and a high
ion-exchange capacity. Such a copolymer may be obtained by
copolymerizing the compound (3) with another polymerizable monomer
(hereinafter referred to as a comonomer) copolymerizable with the
compound (3). The comonomer may be one type or at least two
types.
[0058] The comonomer may, for example, be a perfluoromonomer such
as tetrafluoroethylene, a perfluoro(.alpha.-olefin) such as
hexafluoropropene, a perfluorodiene such as perfluoro(3-butenyl
vinyl ether), perfluoro(allyl vinyl ether) or
perfluoro(3,5-dioxa-1,6-heptadiene), a perfluorinated cyclic
monomer such as perfluoro(2,2-dimethyl-1,3-dioxole),
perfluoro(1,3-dioxole),
perfluoro(2-methylene-4-methyl-1,3-dioxolane) or
perfluoro(4-methoxy-1,3-dioxole), or perfluorovinyl ether such as
perfluoro(alkyl vinyl ether) or perfluoro(alkoxyalkyl vinyl
ether).
[0059] Further, as the comonomer, it is possible to use a comonomer
other than a perfluoromonomer, which may be copolymerized with the
compound (3) alone or may be copolymerized with the compound (3)
together with the above exemplified comonomer. Specifically, such a
comonomer may, for example, be a fluoroolefin such as
trifluoroethylene, chlorotrifluoroethylene, vinylidene fluoride or
vinyl fluoride, an olefin such as ethylene or propene, a
(perfluoroalkyl)ethylene such as (perfluorobutyl)ethylene, or a
(perfluoroalkyl)propene such as 3-perfluorooctyl-1-propene.
Further, it is possible to use, as a comonomer, a monomer having a
--SO.sub.2F group other than the compound (3), particularly a
perfluorinated monomer having a --SO.sub.2F group.
[0060] The polymerization reaction is not particularly limited as
long as it is carried out under such a condition that radicals are
produced. For example, it may be carried out by bulk
polymerization, solution polymerization, suspension polymerization,
emulsion polymerization, or polymerization in a liquid or
supercritical carbon dioxide.
[0061] A method for producing radicals is not particularly limited.
For example, it is possible to use a method of irradiating
radioactive rays such as ultraviolet rays, .gamma.-rays or electron
rays, and it is also possible to use a method of using a radical
initiator usually used in radical polymerization. The reaction
temperature for the polymerization reaction is not particularly
limited, and for example, it is usually from 15 to 150.degree. C.
In a case where a radical initiator is used, the radical initiator
may, for example, be a bis(fluoroacyl)peroxide, a
bis(chlorofluoroacyl)peroxide, a dialkyl peroxy carbonate, a diacyl
peroxide, a peroxyester, an azo compound or a persulfate.
[0062] When solution polymerization is to be carried out, a solvent
to be used usually preferably has a boiling point of from 20 to
350.degree. C., more preferably from 40 to 150.degree. C. from the
viewpoint of handling efficiency. As the solvent, a solvent is used
wherein growing radicals for the polymerization will cause no or
little chain transfer reaction to the solvent. Such a solvent is
preferably a fluorinated solvent which is usually used for
polymerization of a fluorinated monomer. For example, it may be a
hydrofluorocarbon, a hydrochlorofluorocarbon, a chlorofluorocarbon,
a perfluorocarbon, a polyfluorodialkyl ether, a polyfluorinated
cyclic ether or a polyfluorotrialkylamine.
[0063] Further, it is possible to carry out polymerization by using
a chain transfer agent to adjust the molecular weight. The chain
transfer agent may, for example, be an alcohol such as methanol or
ethanol, the above fluorinated solvent such as a
hydrochlorofluorocarbon which functions also as a chain transfer
agent, or a hydrocarbon such as pentane, hexane or cyclohexane.
[0064] The molecular weight of the polymer (3U) (namely, a
homopolymer or copolymer having monomer units (3U)) is preferably
from 5.times.10.sup.3 to 5.times.10.sup.6, particularly preferably
from 1.times.10.sup.4 to 3.times.10.sup.6. When comonomer units are
contained, it is preferred to contain the monomer units (3U) in a
proportion of from 0.1 to 99.9 mol % based on the total of monomer
units. The proportion of the monomer units (3U) is particularly
preferably from 5 to 90 mol %, especially preferably from 10 to 75
mol %.
[0065] The copolymer in the polymer (3U) is particularly useful for
an application to a precursor of an electrolyte material for a
brine electrolysis or a fuel cell. Further, when the copolymer is
used for an application to a brine electrolysis or a fuel cell, the
comonomer is preferably selected from perfluorinated comonomers
from the viewpoint of durability. The comonomer is preferably a
perfluoroolefin such as tetrafluoroethylene or a perfluoro(alkyl
vinyl ether), especially preferably a tetrafluoroethylene.
[0066] A sulfonic acid polymer useful as an electrolyte material
for a brine electrolysis or a fuel cell, can be produced by
subjecting a fluorosulfonyl group of a polymer (3U) to alkali
hydrolysis, or acid-treatment after such alkali hydrolysis. The
sulfonic acid polymer to be obtained is a polymer containing units
represented by the following formula (4U). However, the sulfonic
acid polymer to be obtained may contain units wherein only one
--SO.sub.2F group of the monomer unit (3U) is converted to a
--SO.sub.3M group, or it may contain a small amount of unreacted
monomer unit (3U). M in the following formula (4U) represents a
hydrogen atom or a counter ion. Further, a polymer having the
following units (4U) will be referred to also as a polymer
(4U).
##STR00017##
[0067] The molecular weight of the polymer (4U) (namely, a
homopolymer or a copolymer having units (4U)) is preferably from
5.times.10.sup.3 to 5.times.10.sup.6, particularly preferably from
1.times.10.sup.4 to 3.times.10.sup.6. When the comonomer units are
contained, the units (4U) are preferably contained in a proportion
of 0.1 to 99.9 mol % based on the total monomer units. The
proportion of the units (4U) is particularly preferably from 5 to
90 mol %, especially preferably from 10 to 75 mol %.
[0068] In alkali hydrolysis of the polymer (3U), it is preferred to
use an alkali metal hydroxide or an alkali metal carbonate. It is
also possible to use a compound represented by a formula
NR.sup.1R.sup.2R.sup.3R.sup.4(OH) (wherein each of R.sup.1 to
R.sup.4 which are independent of each other, is a hydrogen atom or
a C.sub.1-5 alkyl group). In acid-treatment, it is preferred to use
hydrochloric acid, nitric acid or sulfuric acid. Consequently, a
fluorosulfonyl group can be converted to a sulfonate
(--SO.sub.3M.sup.1 group: wherein M.sup.1 represents a counter
ion). Here, M.sup.1 is preferably an alkali metal ion or a
N.sup.+R.sup.1R.sup.2R.sup.3R.sup.4. The alkali metal ion is
preferably a sodium ion, a potassium ion or a lithium ion. Further,
N.sup.+R.sup.1R.sup.2R.sup.3R.sup.4 is preferably
N.sup.+(CH.sub.3).sub.4, N.sup.+(CH.sub.2CH.sub.3).sub.4,
N.sup.+(CH.sub.2CH.sub.2CH.sub.3).sub.4 or
N.sup.+(CH.sub.2CH.sub.2CH.sub.2CH.sub.3).sub.4.
[0069] It is preferred to obtain a polymer wherein M.sup.1 in the
sulfonate group is an alkali metal ion, by reacting a sulfonic acid
group-containing polymer with an alkali metal hydroxide. Further,
it is preferred to obtain a polymer wherein M.sup.1 in the
sulfonate group is N.sup.+R.sup.1R.sup.2R.sup.3R.sup.4, by reacting
a fluorosulfonyl group-containing polymer with a compound
represented by the formula NR.sup.1R.sup.2R.sup.3R.sup.4(OH).
Further, the sulfonate group-containing polymer obtained by
hydrolysis can be converted to have other counter ions by immersing
the polymer in an aqueous solution containing ions which can be
counter ions different from M.sup.1. Further, the sulfonate group
(--SO.sub.3M.sup.1 group) can be converted to a sulfonic acid group
(--SO.sub.3H group) by treatment with an acid such as hydrochloric
acid, nitric acid or sulfuric acid. A method for converting such
groups may be carried out in accordance with a known method and
conditions.
[0070] The present invention is a sulfonic acid group-containing
polymer containing at least one type of units represented by the
following formula (5U) or at least one type of such units and at
least one type of other units. Each of R.sup.f1 and R.sup.f2 in the
following formula (5U) is the same as the above perfluoroalkylene
group. Such a polymer (5U) has its molecular weight of from
5.times.10.sup.3 to 5.times.10.sup.6, and when other units are
contained, units is represented by the formula (5U) are preferably
contained in an amount of from 0.1 to 99.9 mol %.
##STR00018##
[0071] The sulfonic acid group-containing polymer (5U) is
particularly suitable as an electrolyte material for a polymer
electrolyte fuel cell.
[0072] The polymer (3U) of the present invention is excellent in
adhesion with other substrates. Further, it has a low refractive
index as compared with a hydrocarbon type polymer, and it has a
high refractive index as compared with a perfluoropolymer having no
functional groups, whereby it is also useful as an optical
material. Further, the polymer (4U) or the polymer (5U) obtainable
by the process of the present invention are not limited in their
application to an electrolyte material for a brine electrolysis or
a fuel cell, and it is possible to use them for various
applications as solid electrolyte materials. For example, such
polymers may be used for a proton permselective membrane to be used
for water electrolysis, hydrogen peroxide production, ozone
production or waste acid recovery, or may be used for a cation
exchange membrane for electrodialysis to be used for desalination
or salt production. Further, they may also be used for a polymer
electrolyte for a lithium ion cell, a solid acid catalyst, a cation
exchange resin, a sensor using modified electrodes, an ion exchange
filter for removing a trace amount of ions in an air, or an
actuator. That is, the polymer (4U) may be used as a material for
various electrochemical processes. Further, the polymer (4U) may be
used for a membrane for diffusion dialysis to be used for
separation and purification of an acid, a base or a salt, a charged
porous membrane for protein separation (e.g. a charged reverse
osmosis membrane, a charged ultrafiltration membrane or a charged
microfiltration membrane), a dehumidifying membrane or a
humidifying membrane.
EXAMPLES
[0073] Now, the present invention will be described in further
detail with reference to Examples, but it should be understood that
the present invention is by no means restricted thereto. The
compounds and the reaction conditions used for a reaction scheme
described in each Example are shown. Further, abbreviations
described in each Example are the following.
[0074] GC: Gas chromatograph
[0075] GPC: Gel permeation chromatograph
[0076] HCFC 225: Fluorinated solvent. A mixture of
CF.sub.3CF.sub.2CHCl.sub.2/CClF.sub.2CF.sub.2CHClF=45/55 (mass
ratio).
[0077] HCFC 225cb: Fluorinated solvent.
CClF.sub.2CF.sub.2CHClF.
[0078] R 113: Fluorinated solvent. CCl.sub.2FCClF.sub.2.
[0079] BF.sub.3.OEt.sub.2: Boron trifluoride ether complex
Example 1
##STR00019##
[0081] A 5 L 4-necked flask was equipped with a thermometer, a
Dimroth condenser and a stirrer. Under an atmosphere of nitrogen,
1,800 ml of diglyme was added. Then, AgF (593 g, 4.68 mol) was
added with stirring. A reactor was equipped with a dropping funnel,
and the reactor was cooled in an ice bath until its inner
temperature became at most 10.degree. C. While maintaining the
inner temperature of at most 10.degree. C., sulfone (10b) (843 g,
4.68 mol) was dropped from a dropping funnel over a period of 2
hours, followed by stirring for 1 hour in a water bath.
[0082] Again, the reactor was cooled in an ice bath, and while
maintaining the inner temperature of at most 10.degree. C.,
trans-1,3-dibromo-2-butene (10a-1) (500 g, 2.34 mol) dissolved in
500 g of diglyme was dropped from a dropping funnel over a period
of 1.5 hours. After the dropping, stirring was continuously carried
out for 11 hours. When the crude liquid of the reaction was
subjected to a GC analysis, it was confirmed that the reaction was
almost finished.
[0083] The crude liquid of the reaction was subjected to suction
filtration by using celite. The filtrate was transferred to a 5 L
4-necked flask, and under a reduced is pressure, the solvent was
distilled off by heating. 1,067 g of the content remained in the
flask. 3,200 g of deionized water was added thereto, followed by
stirring for 15 minutes for water-washing treatment. 863 g (GC:
73.66%) of the lower layer was recovered by a separating funnel.
After the filtration with sea sand, the recovered liquid was dried
with magnesium sulfate.
[0084] 500 g of a compound (1-1) was obtained by distillation. The
boiling point 137 to 140.degree. C./0.27 to 0.40 kPa. Yield
47%.
[0085] .sup.1H-NMR (300.4 MHz, solvent: CDCl.sub.3) .delta. (ppm):
6.0 (m, 2H), 4.7 (m, 4H).
[0086] .sup.19F-NMR (282.7 MHz, solvent: CDCl.sub.3, standard:
CFCl.sub.3) .delta. (ppm): 43.6 (2F), -84.1 (4F), -111.5 (4F).
Example 2
##STR00020##
[0088] A 5 L 4-necked flask was equipped with a thermometer, a
Dimroth condenser and a stirrer. Under an atmosphere of nitrogen,
the compound (1-1) (475 g, 1.05 mol), 2,800 g of 1,2-dichloroethane
and 352 g of m-chloroperbenzoic acid (m-CPBA) (purity >65%) were
added, and reflux was carried out for 7 hours. When the mixture was
subjected to a GC analysis, the degree of conversion was 36.4%.
1,029 g of 1,2-dichloroethane and 352 g of M-CPBA (purity >65%)
were further added into a reactor, and reflux was carried out for
31 hours. The degree of conversion was 94.6%.
[0089] The crude liquid of the reaction was filtrated to recover
5,132 g. It was washed twice with a saturated sodium carbonate
aqueous solution and with 4.8 mol/l of a sodium chloride aqueous
solution, and it was subjected to liquid separation to obtain 4,859
g of a crude liquid of the reaction.
[0090] Such a crude liquid was dried over sodium sulfate and
filtrated, and then it was concentrated by an evaporator and dried
to obtain 400 g of a compound (11-1).
[0091] .sup.1H-NMR (300.4 MHz, solvent: CDCl.sub.3) .delta. (ppm):
4.3 (m, 2H), 4.2 (m, 2H), 2.2 (m), 3.3 (m, 2H).
[0092] .sup.19F-NMR (282.7 MHz, solvent; CDCl.sub.3, standard:
CFCl.sub.3) .delta. (ppm): 43.6 (2F), -84.3 (4F), -111.5 (4F).
Example 3
##STR00021##
[0093] Acetonide Formation
[0094] A 1 L 4-necked flask was equipped with a thermometer, a
stirrer and a Dean-Stark trap. Under an atmosphere of nitrogen,
71.32 g (152.3 mmol) of the compound (11-1), 263 g of dried
acetone, 290 g of dried toluene, 58.77 g (152.2 mmol) of a compound
(15-1) and BF.sub.3.OEt.sub.2 (2.67 g, 18.8 mmol) were sequentially
added.
[0095] The reactor was heated in an oil bath and heated to the
inner temperature of 90.degree. C. under a normal pressure to
distill 300 ml of the solvent. Then, stirring was carried out for 4
hours at the inner temperature of 100.degree. C. The degree of
conversion analyzed by gas chromatograph was 97%.
Ketal Exchange
[0096] The Dean-Stark trap was removed from the flask and a simple
distillation device was attached thereto. It was heated to the
inner temperature of 90.degree. C. at 33 kPa to distill 239 g of
toluene. Into the reactor, BF.sub.3.OEt.sub.2 (1.33 g, 9.37 mmol)
was added, and a reaction was carried out at 40 kPa at the inner
temperature of 90.degree. C. for 2.5 hours. Further, into the
reactor, BF.sub.3.OEt.sub.2 (1.39 g, 9.79 mmol) was added, and a
reaction was carried out at 40 kPa at the inner temperature of
90.degree. C. for 2 hours to obtain 141.82 g of a reaction crude
liquid of a compound (13-1). The degree of conversion was
96.4%.
[0097] In the same manner, 822.6 g (degree of conversion: 93.9%) of
the reaction crude liquid of the compound (13-1) was obtained from
328.24 g (701 mmol) of the compound (11-1).
[0098] Two of the above reaction crude liquid were combined and
heated to the inner temperature of 100.degree. C. at 40 kPa. Then,
the pressure was gradually decreased to 0.13 kPa. After that, when
the content became bubbly at the inner temperature of 107.degree.
C. by heating, the operation to distill off low-boiling components
was stopped. The content in the flask was 709 g.
[0099] A silica gel ("silica gel 60", spherical shape, supplied by
Kanto Chemical Co., Inc.) was used for a stationary phase, and
hexane and HCFC 225 were used for a mobile phase to carry out
column purification, whereby 343.7 g of the compound (13-1) was
obtained.
[0100] .sup.1H-NMR (300.4 MHz, solvent: CDCl.sub.3) .delta. (ppm):
4.55 (m, 2H), 4.44 to 4.14 (m, 6H), 1.50 (s), 1.44 (s), (3H by
combining 1.50 ppm and 1.44 ppm).
[0101] .sup.19F-NMR (282.7 MHz, solvent: CDCl.sub.3, standard:
CFCl.sub.3) .delta. (ppm): 43.5 (2F), -80.5 (1F), -81.8 (3F), -82.6
(3F), -85.3 (4F), -86.8 (1F), -111.7 (4F), -130.2 (2F), -132.5
(1).
Example 4
##STR00022##
[0103] Into a stainless steel autoclave (inner volume: 3,000 mL),
4,200 g of
CF.sub.3CF.sub.2CF.sub.2OCF(CF.sub.3)CF.sub.2OCF(CF.sub.3)COF
(hereinafter referred to as an inactive fluid A) was introduced. As
a transport device, a bellows pump having an ability of 300 L/Hr
was used to circulate the inactive fluid A. By adjusting the amount
of the refrigerant to flow through a heat exchanger provided in the
middle of a circulation path, the temperature of the inactive fluid
A in the autoclave was maintained at 20.degree. C. A fluorine gas
diluted to 25% with a nitrogen gas (hereinafter referred to as a 25
diluted fluorine gas) was continuously supplied from a stainless
steel ejector provided in the pipe in a circulation path at a flow
rate of 81.1 L/h. While maintaining the above conditions, the
circulation was carried out for 1 hour.
[0104] Then, 300 g (0.29 mol) of the compound (13-1) was dissolved
in R 113 (300 g), and the mixture was continuously supplied through
a raw material supplying pipe provided in the middle of the
circulation path with a flow amount of 56 g/h. Further, the
inactive liquid containing a fluorinated compound was continuously
withdrawn to make the volume of the liquid in the autoclave be
approximately constant. As a result of subjecting the withdrawn
crude liquid to a GC analysis, no presence of the compound (13-1)
was confirmed in the inactive liquid.
[0105] The fluorinated product is an inactive liquid, and as the
reaction proceeded, the circulating inactive fluid A was gradually
replaced by the fluorinated product (compound (14-1)), whereby the
circulating inactive fluid A was changed to a mixture of the
inactive fluid A and the fluorinated product (compound (14-1)).
Further, since the inactive fluid A and the fluorinated product
(compound (14-1)) are the compounds having different boiling
points, it is possible to easily separate them by distillation.
[0106] After supplying the entire solution of the compound (13-1),
a 25% diluted fluorine gas was supplied for 48.5 hours. Further,
only a nitrogen gas was blown in for 0.5 hour, and a crude liquid
of the reaction was withdrawn. The total amount of the recovered
crude liquid was 4,409 g. The obtained crude liquid was put in a
flask, followed by heating and stirring under a reduced pressure,
whereby it was possible to recover 331 g of a solution having the
fluorinated product (compound (14-1)) as a main component
(hereinafter referred to as a fluorinated crude liquid B).
[0107] Then, 230 g of the above fluorinated crude liquid B was
dissolved in R113 (230 g), and the mixture was introduced in an
autoclave (500 mL, made of nickel) followed by stirring, and it was
maintained at 25.degree. C. At the gas outlet of the autoclave, a
condenser kept at 20.degree. C., a NaF pellet-packed bed and a
condenser kept at -10.degree. C. were set in series. Further, a
liquid-returning line was set to return the condensed liquid from
the condenser kept at -10.degree. C., to the autoclave. After a
nitrogen gas was blown in for 1 hour, a fluorine gas diluted to 20%
with a nitrogen gas (hereinafter referred to as 20% fluorine gas)
was blown in at 11.4 NL/h.
[0108] Then, the temperature of the reaction solution was raised
from 25.degree. C. to 40.degree. C., and with the 20% fluorine gas
being blown in at the same constant flow rate into the autoclave, 9
ml of R 113 solution having a benzene concentration of 0.012 g/mL
was injected, and the benzene injection inlet of the autoclave was
closed, followed by stirring for 0.4 hour. 6 ml of the above
benzene solution was injected, and the benzene injection inlet of
the autoclave was closed, followed by stirring for 0.4 hour.
Further, the same operation was repeated for 22 times. The total
injected amount of benzene was 1.9 g and the total injected amount
of R 113 was 153 ml.
[0109] Further, a nitrogen gas was blown in for 1 hour. When the
object was quantified by .sup.19F-NMR, formation of the compound
(14-1) was confirmed, and as a result of the .sup.19F-NMR analysis,
it was confirmed that the compound was contained in a yield of
97%.
[0110] A reaction was carried out in the same manner with respect
to the remaining fluorinated crude liquid B. Two of the reaction
liquids were combined, and the solvent was distilled off to obtain
304 g of the compound (14-1).
[0111] .sup.19F-NMR (282.7 MHz, solvent CDCl.sub.3, standard:
CFCl.sub.3) .delta. (ppm): 45.5 (2F), -80.0 to -82.0 (18F), -84.6
to -87.5 (3F), -112.5 (4F), -113.0 to -123.0 (2F), -130.3 (2F),
-132.1 (1F).
Example 5
##STR00023##
[0113] A stirring bar was put in a 500 mL 4-necked flask provided
with a thermometer, and a distillation device was attached thereto.
Under an atmosphere of nitrogen, 304 g of the compound (14-1) was
introduced. Then, 3.36 g of KF (0.06 mol, "Chloro-catch F",
manufactured by MORITA CHEMICAL INDUSTRIES, CO., LTD.) was added
with stirring, followed by gradual heating in an oil bath. At the
inner temperature of 87.degree. C.,
CF.sub.3CF.sub.2CF.sub.2OCF(CF.sub.3)COF started to be distilled.
When the inner temperature reached 110.degree. C. taking over a
period of 2 hours, the inner temperature was kept at that level for
1 hour. Once it was cooled down, the distillation under a reduced
pressure was carried out to obtain 176 g of a compound (2-1). The
boiling point 117 to 144.degree. C./0.67 to 0.80 kPa.
[0114] .sup.19F-NMR (282.7 MHz, solvent CDCl.sub.3, standard:
CFCl.sub.3) .delta. (ppm): 45.6 (2F), 27.2, 26.0, 25.0 (1F by
combining 3 peaks), -80.1 to -81.8 (7F), -82.2 (4F), -112.5 (4F),
-118.7, -119.4, -123.8, -129.4 (2F by combining 4 peaks).
Example 6
##STR00024##
[0116] Into a tube reactor (made of inconel) having an inner
diameter of 1.6 .mu.m, glass beads (central particle size of from
105 to 125 .mu.m, glass bead #150, manufactured by GAKUNAN KOHKI
CO., LTD.) were filled until the filled height reached 40 cm, and
then the tube reactor was heated to 325.degree. C. while
continuously heating the tube reactor, a gas mixture comprising 99
mol % of nitrogen gas and 1 mol % of vaporized gas of the compound
(2-1) preliminary heated in the raw material line, was introduced
from the bottom of the tube reactor in such a manner that the
linear speed of the gas mixture in the tube reactor would be 2.65
cm/s. Further, at the top end of the tube reactor, a dry ice trap
was set up. In such a state, the above gas mixture was supplied for
2 hours, and then only nitrogen gas was let flow through for 1
hour. The amount of the compound (2-1) introduced in the tube
reactor was 3.96 g.
[0117] As a result of a GC analysis of the liquid (2.45 g)
recovered in the dry ice trap, no raw material compound was
confirmed, and the presence of the desired product having a purity
of 85.5% was confirmed. The actual yield of the compound (3-1) was
60% taking into the consideration of the recovery rate of the above
liquid. By distilling the heat-decomposition crude liquid obtained
in the same manner, the objective compound (3-1) (a mixture of
anti-form and syn-form) was obtained. The boiling point was from 99
to 102.degree. C./0.40 to 0.53 kPa.
[0118] .sup.19F-NMR of the anti-form (282.7 MHz, solvent
CDCl.sub.3, standard: CFCl.sub.3) .delta. (ppm): 45.4 (2F), -81.6
(4F), -82.4 (4F), -112.6 (4F), -124.7 (2F), -128.2 (2F).
[0119] .sup.19F-NMR of the syn-form (282.7 MHz, solvent CDCl.sub.3,
standard: CFCl.sub.3) .delta. (ppm): 45.5 (2F), -81.8 (4F), -82.4
(4F), -112.6 (4F), -124.9 (2F), -127.3 (2F).
[0120] When the ratio between the anti-form and the syn-form was
obtained from NMR, the ratio was such that
anti-form:syn-form=3.3:1.0.
Example 7
Synthesis of Polymer
[0121] Into an autoclave (inner volume of 30 cm.sup.3, made of
stainless steel), 1.33 g of the compound (3-1), 18.52 g of HCFC
225cb, 5.51 mg of methanol and 0.90 mg of peroyl IPP (diisopropyl
peroxydicarbonate) were introduced, followed by cooling with liquid
nitrogen and degassing. The inner temperature was increased to
40.degree. C., and tetrafluoroethylene was introduced into the
autoclave all at once at the initial stage. The pressure was
adjusted to 0.49 MPa (gauge pressure). While maintaining the
temperature to be constant, polymerization was carried out for 8
hours. The pressure at the completion of polymerization was 0.41
MPaG. The inside of the autoclave was cooled down to stop the
polymerization, and the gas inside the system was purged.
[0122] After diluting the reaction liquid with HCFC 225cb, hexane
was added, and a polymer was agglomerated and filtrated. After
that, the polymer was stirred in HCFC 225cb, and it was
reagglomerated by hexane. It was dried under reduced pressure over
night at 80.degree. C., to obtain 0.76 g of the polymer.
[0123] The content of monomer units of compound (3-1) obtained by
fluorescent X-rays was 14.1 mol %, and the ion-exchange capacity
was 1.58 meq/g. The molecular weight calculated as polystyrene,
obtained by GPC was 1,100,000.
Example 8
Synthesis of Acid Type Polymer and Evaluation of Physical
Property
[0124] The polymer obtained in Example 7 was subjected to press
molding at 300.degree. C. and was processed into a film (film
thickness; approximately 100 .mu.m). Then, into an aqueous solution
containing 30 mass % of dimethylsulfoxide and 15 mass % of KOH, the
polymer film was immersed at 80.degree. C. for 16 hours, whereby a
--SO.sub.2F group in the polymer film was hydrolyzed and converted
to a --SO.sub.3K group.
[0125] Further, the polymer film was immersed in a 3 mol/L
hydrochloric acid aqueous solution at 50.degree. C. for 2 hours,
and then the hydrochloric acid was changed. Such acid treatment was
repeatedly carried out 4 times. It was sufficiently washed with
deionized water, and a polymer film having a --SO.sub.3K group in
the polymer film converted to a --SO.sub.3H group, was
obtained.
[0126] The measurement of the softening temperature was carried out
as follows. By using a dynamic viscoelasticity measuring device
DVA200 (manufactured by ITK Co., Ltd.), the dynamic viscoelasticity
of the above acid type film was carried out with a sample width of
0.5 cm, a length between chucks of 2 cm, a measuring frequency of 1
Hz and a rate of temperature increase of 2.degree. C./min, and a
temperature at which the elastic modulus became a half of the value
at 50.degree. C., was taken as a softening temperature. The
softening temperature of the above acid type polymer was
117.degree. C. Further, in the measurement of the dynamic
viscoelasticity, the glass transition temperature (Tg) obtained
from the peak value of tan .delta. was 158.degree. C.
[0127] The specific resistance was measured by a known 4-terminal
method and under a condition of constant temperature and humidity
such as 80.degree. C. and 95% RH with AC of 10 kHz and 1 V, wherein
to a film having a width of 5 mm, a substrate having 4-terminal
electrodes disposed every 5 mm was closely contacted. The specific
resistance of the above acid type film was 2.2 .OMEGA.cm.
COMPARATIVE EXAMPLE
[0128] With respect to a film of a copolymer (ion exchange
capacity: 1.10 meq/g, T.sub.Q 225.degree. C.) of
tetrafluoroethylene and
CF.sub.2.dbd.CFOCF.sub.2CF(CF.sub.3)OCF.sub.2CF.sub.2SO.sub.2F
converted to an acid-type, the physical properties were measured in
the same manner as Example 8. The softening temperature and Tg were
respectively 76.degree. C. and 109.degree. C. The specific
resistance was 3.6 .OMEGA./cm. Further, T.sub.Q value (unit:
.degree. C.) of the above copolymer is an index for a molecular
weight, and it is a temperature at which the extrusion amount would
be 100 mm.sup.3/sec when melt extrusion of a polymer is carried out
by using a nozzle having a length of 1 mm and an inner diameter of
1 mm and under a condition of an extrusion pressure of 2.94 MPa. By
using a flow tester CFT-500A (manufactured by Shimadzu
Corporation), the extrusion amount was measured by changing the
temperature, and the T.sub.Q value at which the extrusion amount
became 100 mm.sup.3/sec, was obtained.
[0129] The --SO.sub.2F group-containing polymer obtained by
polymerizing the compound of the present invention is useful for an
application as a precursor of an electrolyte material. That is, by
hydrolyzing a --SO.sub.2F group of such a polymer, it is possible
to obtain a polymer having a --SO.sub.3H group, and the polymer
having such a --SO.sub.3H group is useful as an electrolyte
material for e.g. brine electrolysis or a fuel cell. For example,
such a polymer having a --SO.sub.3H group can be used as an
electrolyte for an ion-exchange membrane or in a catalyst layer for
a polymer electrolyte fuel cell. Other than such an application,
such a polymer having a --SO.sub.3H group can be used for a
material of various electrochemical processes as a solid
electrolyte material. Further, the --SO.sub.2F group-containing
polymer itself is useful for an application as an optical material,
etc.
[0130] The entire disclosure of Japanese Patent Application No.
2007-208024 filed on Aug. 9, 2007 including specification, claims
and summary is incorporated herein by reference in its
entirety.
* * * * *