JP-2026075949-A - Sealant for fuel cells and fuel cells using the same

Abstract

【assignment】 The present invention provides a sealant for fuel cells that exhibits excellent low-contamination properties, and a fuel cell having said sealant. [Solution] A sealant for fuel cells containing (A) a photopolymerization initiator with a weight-average molecular weight of 400 or more determined by gel permeation chromatography (GPC), and (B) a curable compound. [Selection Diagram] None

Inventors

• 小淵 香津美
• 飯塚 真之
• 内藤 正弘

Assignees

• 日本化薬株式会社

Dates

Publication Date

20260511

Application Date

20241023

Claims (8)

1. A fuel cell sealant containing (A) a photopolymerization initiator with a weight-average molecular weight of 400 or more as determined by gel permeation chromatography (GPC), and (B) a curable compound.
2. Furthermore, the fuel cell sealant according to claim 1, further comprising (C) filler.
3. The fuel cell sealant according to claim 1, wherein the (A) photopolymerization initiator has two or more sites in one molecule that generate radicals upon irradiation with ultraviolet light or visible light or heat.
4. The fuel cell sealant according to claim 1, wherein the (A) photopolymerization initiator is a polymer of 2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propanone.
5. The fuel cell sealant according to claim 1, comprising a polybutadiene compound having a reactive group in its molecule as the curable compound (B).
6. The fuel cell sealant according to claim 1, comprising a urethane (meth)acrylate compound as the curable compound (B).
7. The fuel cell sealant according to claim 1, used as a sealant for polymer electrolyte membranes.
8. A fuel cell comprising a fuel cell sealant according to any one of claims 1 to 7.

Description

This invention relates to a sealant for fuel cells and a fuel cell using the same. A fuel cell is a power generation system that uses hydrogen, obtained by reforming gasoline or natural gas, as fuel, and extracts electricity from the energy released when hydrogen chemically reacts with oxygen. A type of fuel cell, the polymer electrolyte fuel cell, uses an ion exchange membrane as its electrolyte. Because the electrolyte is thin and has a high current density, it can be made smaller and lighter, and development is progressing for use as a power source for homes and automobiles. In fuel cells, high-barrier, high-adhesion sealants are required to prevent leakage of reaction gases and coolant, and to maintain the power generation unit, and are being developed (Patent Document 1). Furthermore, in polymer electrolyte fuel cells, there is a need to achieve rapid bonding between the polymer electrolyte membrane (perfluorocarbon material having sulfonic acid groups, such as Chemours' Nafion) and other substrates (heat-resistant polymers, metals, etc.) to improve productivity. Therefore, the development of photocurable sealants is progressing (Patent Document 2). Patent No. 7318366Patent No. 7235037 The sealant for fuel cells of the present invention (also simply referred to as "sealant") contains (A) a photopolymerization initiator with a weight-average molecular weight of 400 or more determined by gel permeation chromatography (GPC), and (B) a curable compound. It is particularly suitable as a sealant for polymer electrolyte membranes in polymer electrolyte fuel cells. The sealant for polymer electrolyte membranes is mainly used to hold membrane electrode assemblies (MEAs) in a gasket. The sealant of the present invention exhibits excellent low-contamination properties. Low-contamination properties can be evaluated by weight change rate and electrical conductivity. The weight change rate is an indicator of the amount of eluted components; it is preferably 3% or less, more preferably 2% or less, and particularly preferably 1% or less after 240 hours at 95°C. Electrical conductivity is an indicator of the degree of electrical influence of the eluted components; the initial value is preferably 2 μS/cm or less, more preferably 1.5 μS/cm or less, and after 240 hours at 95°C, it is preferably 20 μS/cm or less, more preferably 15 μS/cm or less, and particularly preferably 10 μS/cm or less. Specific measurement methods are described in the examples below. [(A) Photopolymerization initiators with a weight-average molecular weight of 400 or more as determined by gel permeation chromatography (GPC)] The sealant of the present invention contains (A) a photopolymerization initiator (also simply referred to as "component (A)") having a weight-average molecular weight of 400 or more as determined by gel permeation chromatography (GPC). By using a photopolymerizable initiator with a weight-average molecular weight of 400 or more, elution into hot water is suppressed, resulting in good low-contamination properties. From the viewpoint of low-contamination properties, curability, and solubility in the composition, the weight-average molecular weight of component (A) is preferably 400 at the lower limit and 1500 at the upper limit. In this invention, gel permeation chromatography (GPC) is measured under the following conditions. Measurement device: HLC-8320GPC (Tosoh Corporation) Analytical columns: Three TSKgel SuperMultiporeHZ-M columns were used. Eluent: THF (tetrahydrofuran) Flow rate: 0.35ml/min Measurement temperature: 40℃ Detector: Differential refractometer Molecular weight standard: Polystyrene (A) Examples of photopolymerization initiators with a weight-average molecular weight of 400 or more as determined by gel permeation chromatography (GPC) include Esacure ONE (manufactured by IGM RESINS, a high molecular weight α-hydroxyketone-based photopolymerization initiator: oligo(2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propanone), Omnipol TP (manufactured by IGM RESINS, a high molecular weight phosphorus-based photopolymerization initiator: polymer of ethyl(2,4,6-trimethylbenzoyl)-phenylphosphorinate), Omnipol 910 (manufactured by IGM RESINS, a high molecular weight aminoalkylphenone-based photopolymerization initiator: polyethylene glycol di(β-4[4-(2-dimethylamino-2-benzyl)butanoylphenyl]piperazine)propionate), Irgacure Examples include OXE04 (manufactured by BASF, an oxime ester-based photopolymerization initiator). Furthermore, from the viewpoint of curability and low contamination, component (A) preferably has two or more radical-generating sites in one molecule that are irradiated with ultraviolet or visible light or heat. Compounds in which the radical-generating site (2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propanone) is repeated within the molecule, such as polymers of 2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propanone, are particularly preferred because they have high radical generation efficiency, i.e.,