Crosslinkable aromatic resin having protonic acid group, and ion conductive polymer membrane, binder and fuel cell using the resin

Abstract

The present invention provides a proton-acid group-containing cross-linkable aromatic resin having a cross-linking group suitable for use as an electrolyte membrane and a binder used in fuel cells, and a polymer for fuel cells obtained from the resin. Electrolyte membranes and binders, and fuel cells using them. This protonic acid group-containing crosslinkable aromatic resin has a crosslinking group that is not derived from a protonic acid group and can be crosslinked without generating a detachment component, and exhibits excellent ion conductivity, heat resistance, water resistance, Adhesion, and low methanol permeability. As the above-mentioned crosslinking group that is not derived from a protonic acid group and can be crosslinked without generating a detachment component, an alkyl group having 1 to 10 carbon atoms and a carbonyl group directly bonded to an aromatic ring are used as a crosslinking group, or A carbon-carbon double bond or a carbon-carbon triple bond is a better choice as the crosslinking group. Aromatic resins such as aromatic polyethers, aromatic polyamides, aromatic polyimides, aromatic polyamideimides, and aromatic polypyrroles having the above-mentioned crosslinking groups are proton acid group-containing crosslinking aromatic resins. A good choice for family resins.

Description

technical field [0001] The present invention relates to an ion-conductive proton-containing acid group-containing cross-linkable aromatic resin used in fuel cells using hydrogen, ethanol, etc. as fuel, a polymer film obtained by using the resin, an adhesive, and The fuel cell. Background technique [0002] [Polymer Fuel Cell] [0003] In recent years, due to environmental problems, the demand for new energy storage or power generation elements has become great in society. As one of these elements, the fuel cell has attracted people's attention, and has become the most anticipated power generation element due to its low pollution and high efficiency characteristics. A fuel cell is a battery that oxidizes fuels such as hydrogen and methanol using oxygen or air electrochemical means to convert the chemical energy of the fuel into electrical energy and take it out. [0004] Such fuel cells are classified into phosphoric acid type, molten carbonate type, solid oxide type, and ...

AI Technical Summary

Problems solved by technology

Therefore, a DMFC using a protonic acid-based fluorine-based polymer electrolyte membrane has a problem of a voltage drop due to methanol crossover and poor power generation efficiency.

In addition, this proton acid group-containing fluorine-based polymer has the same problems as other fluorine-containing resins: it has low adhesion, it is difficult to adhere to electrodes or membranes, it is very expensive, and if it is incinerated when it is discarded, hydrofluoric acid will be generated. gas

[0014] However, the heat resistance and chemical durability of proton-containing acid group-containing hydrocarbon-based polymers whose main chain is an aliphatic chain are low, and when they are used as polymer electrolytes in polymer electrolyte fuel cells, there are The problem of deterioration of characteristics over time

For example, sulfonated polystyrene has a glass transition temperature of about 125°C, and the heat generated during power generation causes the electrolyte membrane to soften and cause deformation.

In addition, there is a problem that the tertiary carbon with the main chain structure is easily attacked by free radicals, and hydrogen at the α position is easily released in the battery.

However, this method has the following problems: it is necessary to introduce a large amount of basic polymers that are not water-soluble and water-absorbent, so that the composition ratio of the proton acid group-containing resin is reduced, and the ion conductivity is low.

In addition, there is also a problem that the reaction of forming a salt is an equilibrium reaction, for example, since the protonic acid that moves in the membrane during power generation undergoes repeated dissociation and recombination, the sulfonated resin slowly dissolves out.

However, the above method also belongs to the cross-linking mechanism accompanied by detachment of sulfuric acid, hydrochloric acid, chlorine gas, etc., and has the following problems: the cross-linking density is different between the surface of the film and the inside of the film or the back of the film, it is difficult to thicken the film, and there may be problems in the film. Voids; escaped acid gases cause corrosion of manufacturing equipment

In addition, the membrane obtained by the above-mentioned cross-linking mechanism using protonic acid groups also has the following problems: if the cross-linking density is increased, the protonic acid groups will decrease (the equivalent weight of ion exchange groups will increase), and the ion conductivity will decrease.

For example, curing systems for epoxy resins or bismaleimide resins have encountered the following problems: due to the reaction of epoxy or amine groups with protonic acid groups, the protonic acid groups are reduced, and the resulting chains are susceptible to hydrolysis or electrolysis. Therefore, it cannot be used as a cross-linking mechanism for resins containing proton acid groups, nor can it be used as a polymer electrolyte membrane for fuel cells

However, although the protonic acid group-containing fluorine-based polymer can adhere to the polymer electrolyte membrane composed of the protonic acid group-containing fluorine-based polymer, it lacks adhesion to the protonic acid group-containing aromatic hydrocarbon polymer electrolyte membrane. sex

[0028] Furthermore, the binder must have solvent solubility or melt fluidity so that it can be mixed with electrode materials or bonded with electrode materials and films, but resins that have been crosslinked and become infusible cannot be used as adhesives. Adhesive

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