Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From phenol – phenol ether – or inorganic phenolate
Reexamination Certificate
2003-01-14
2004-12-07
Truong, Duc (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From phenol, phenol ether, or inorganic phenolate
C528S089000, C528S148000, C528S373000
Reexamination Certificate
active
06828407
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a polymer electrolyte composition, and, particularly, to a polymer electrolyte composition suitably usable for fuel cells.
2. Description of Related Art
Recently, fuel cells are noticed as clean energy conversion apparatuses of high efficiency. Among them, solid polymer type fuel cells which use a polymer electrolyte membrane having proton conductivity as an electrolyte have a compact structure and can provide high output, and, furthermore, can be operated in a simple system. Therefore, they are expected as movable electric sources for vehicles.
Solid polymer electrolyte is used for solid polymer type fuel cells. Solid polymer electrolyte is a solid polymer material having proton conductive groups such as sulfonic acid group and carboxylic acid group in the polymer chains. The solid polymer electrolyte is utilized for various uses such as electrodialysis and diffusion dialysis in addition to diaphragms of cells.
In a solid polymer type fuel cell, a pair of electrodes are provided on both sides of a solid polymer electrolyte membrane, and electromotive force is obtained by feeding pure hydrogen or reformed hydrogen gas as a fuel gas to one of the electrodes (fuel-electrode) and oxygen gas or air as an oxidant to another electrode (air electrode).
It is known that in this solid polymer type fuel cell, a peroxide is produced in the catalyst layer formed at the interface of the solid polymer electrolyte membrane and the electrodes by a cell reaction, and the peroxide becomes peroxide radicals while being diffused, which deteriorate the polymer electrolyte.
In order to give radical resistance, it is proposed to add in the polymer electrolyte a phosphorus polymer compound comprising an aromatic polymer compound such as polyphenylene ether in which methylenephosphonic acid group is introduced, namely, a phosphorus polymer compound in which a phosphonic acid group is bonded to an aromatic ring through methylene group (see, e.g., JP-A-2000-11756).
Furthermore, as a solid polymer electrolyte having a stable proton conductivity even under the high temperature conditions of higher than 100° C., there are proposed polymer electrolyte compositions comprising a phosphoric acid derivative and a phosphorus polymer compound comprising an aromatic polymer compound such as polyphenylene ether in which methylenephosphonic acid group is introduced, namely, a phosphorus polymer compound in which a phosphonic acid group is bonded to an aromatic ring through methylene group (see, e.g., JP-A-11-503262).
However, there have been desired such polymer electrolyte compositions having the better radical resistance and/or proton conductivity.
BRIEF SUMMARY OF THE INVENTION
The object of the present invention is to provide a polymer electrolyte composition excellent in radical resistance and/or proton conductivity, and a further object is to provide a polymer electrolyte composition membrane using the above polymer electrolyte composition, and a fuel cell using the polymer electrolyte composition membrane.
As a result of intensive research conducted by the inventors for attaining the above objects, it has been found that a polymer electrolyte composition comprising an aromatic polymer phosphonic acid derivative in which phosphonic acid group or the like is directly bonded to an aromatic ring; and at least on selected from the group consisting of a phosphoric acid derivative and a polymer electrolyte is excellent in radical resistance and/or proton conductivity. Thus, the present invention has been accomplished.
That is, the present invention provides a practically superior polymer electrolyte composition containing an aromatic polymer phosphonic acid derivative represented by the following formula (1); and at least on selected from the group consisting of a phosphoric acid derivative and a polymer electrolyte.
(in the formula, -Z- represents —SO
2
— or —CO—, x and y each represent 0.01-0.99 provided that the sum of x and y is 1, —Ar— represents a divalent aromatic group of 4-18 carbon atoms which may contain a hetero atom and may contain one or more substituents, n represents the average number of substituents per unit structure of polymeric moiety containing the aromatic group and is a positive number of 8 or less, and R and R′ each independently represent a hydrogen atom or an alkyl group).
The polymer electrolyte composition of the present invention preferably comprises the aromatic polymer phosphonic acid derivative and the polymer electrolyte, preferably the polymer electrolyte has a proton conductivity of not less than 1×10
−4
S/cm. This polymer electrolyte composition shows good film formability as well as excellent radical resistance, and furthermore can be formed into a composite membrane with a porous substrate membrane.
The polymer electrolyte composition of the present invention preferably comprises the aromatic polymer phosphonic acid derivative and the phosphoric acid derivative. This polymer electrolyte composition can be solid polymer electrolyte which shows proton conductivity even under the high-temperature conditions of 100° C. or higher. The solid polymer electrolyte composition containing the phosphoric acid derivative in an amount of not less than 2 equivalents with respect to the number of phosphorus atoms of the aromatic polymer phosphonic acid derivative shows further excellent and stable proton conductivity. The phosphoric acid derivative is preferably represented by the formula (2).
O═P(OR′″)
k
(OH)
3-k
(2)
(wherein R′″ represents an alkyl group of 1-6 carbon atoms or an aryl group, k represents 0-2 and when k is 2, the two R′″ may be the same or different, and k is preferably 0). This polymer electrolyte composition shows good film formability as well as excellent proton conductivity, and furthermore can be formed into a composite membrane with a porous substrate membrane.
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be explained in more detail below.
The polymer electrolyte composition of the present invention is characterized by containing an aromatic polymer phosphonic acid derivative represented by the aforementioned formula (1).
In the formula (1), -Z- represents —SO
2
— or —CO—, x and y each represent 0.01-0.99 provided that the sum of x and y is 1, —Ar— represents a divalent aromatic group of 4-18 carbon atoms which may contain a hetero atom and —Ar— may contain one or more substituents, n represents the average number of substituents per unit structure of polymeric moiety containing the aromatic group and is a positive number of 8 or less, and R and R′ each independently represent a hydrogen atom or an alkyl group.
As representative examples of —Ar—, mention may be made of the following divalent groups.
Hydrocarbon divalent groups such as o-phenylene, m-phenylene, p-phenylene, naphthalene-1,4-diyl, naphthalene-1,5-diyl, naphthalene-2,6-diyl, naphthalene-2,3-diyl, biphenyl-4,4′-diyl, biphenyl-3,3′-diyl, p-terphenyl-4,4″-diyl, 2,2-diphenylpropane-4′,4″-diyl, fluorene-2,7-diyl, and fluorene-3,6-diyl; divalent groups containing hetero-atom such as carbazole-2,7-diyl, carbazole-3,6-diyl, thiophene-2,5-diyl, dibenzothiophene-2,7-diyl, furan-2,5-diyl, dibenzofuran-2,7-diyl, dibenzofuran-3,6-diyl, diphenylamine-4,4′-diyl, and diphenyl ether-4,4′-diyl; and the like.
These groups may have one or more substituents, and examples of the substituents include the following groups.
Linear or branched alkyl groups which may be substituted with hydroxyl group or halogen atom, such as methyl, ethyl, 2-propyl, t-butyl, hydroxymethyl and trifluoromethyl; linear or branched alkoxy groups which may be substituted with halogen atom, such as methoxy, ethoxy and trifluoromethoxy; phenyl groups which may be substituted with alkyl, alkoxy, phenyl, phenoxy, halogen atom or sulfonic acid group, such as phenyl, methylphenyl, methoxyphenyl, biphenyl, phenoxyphenyl, chlorophenyl an
Hidaka Yasuaki
Sasaki Shigeru
Taniguchi Takumi
Yashiro Arihiro
Sumitomo Chemical Company Limited
Truong Duc
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