Fuel cell component and method for manufacturing the same

Abstract

The present application provides a kind of fuel cell components, it is the fuel cell component of lip 4b directly fixed on the surface of separator 5, wherein the lip 4b is the crosslinked body of radical curing composition containing the following (A) ~ (E) components in a certain proportion, the glass transition temperature (Tg) of the crosslinked body is-30 ℃ or lower.Thereby, the sealing component can be firmly attached to the surface of fuel cell substrate in the form of adhesive-free, further, the thin film of the sealing component can be realized, and excellent sealing performance can be shown in a wide temperature range.(A) (Meth) acryl polymer with (meth) acryl group at the end of molecular chain, (B) monofunctional (meth) acrylic monomer with polycyclic structure and glass transition temperature (Tg) of 0 ℃ or higher, (C) monofunctional (meth) acrylic monomer except the component (B), (D) polyfunctional (meth) acrylic monomer, (E) radical polymerization initiator.

Description

Technical Field

[0001] This invention relates to a fuel cell component used as a constituent element of a fuel cell and a method for manufacturing the same. More specifically, it relates to a fuel cell component comprising a fuel cell substrate and a sealing member, wherein the sealing member is directly fixed (adhesive-free) to the surface of the fuel cell substrate, and a method for manufacturing the same. Background Technology

[0002] Various sealing components are used in the structures that make up fuel cells. For example, in solid polymer fuel cells used in automobiles, sealing components are used to ensure the sealing around the membrane electrode assembly (MEA) and the porous layer, as well as between the separators, in order to prevent leakage of gas and refrigerant and to keep the cell in a moist state. For the above-mentioned sealing components, in addition to various mechanical properties, excellent resistance to aging (compression set) is required to ensure long-term reliability.

[0003] Based on this requirement, the applicant proposed a sealing component formed by crosslinking ethylene-propylene-diene rubber (EPDM) with organic peroxides and potassium fatty acids, etc. (Patent Document 1).

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2017-188417 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] However, the sealing member described in Patent Document 1 lacks adhesive properties, necessitating the application of an adhesive to the contact portion with the separator or similar components to bond and fix the sealing member. Furthermore, since the sealing member is difficult to form into a thin film, there is room for improvement in miniaturizing fuel cells and the like based on this thin-film design.

[0009] Furthermore, with the increasing popularity of fuel cells in recent years, the use of fuel cells in extremely low temperature environments has been envisioned. Therefore, it is required to meet the characteristics of aging resistance, elongation, and compression resistance over a wide temperature range, and ensure excellent sealing performance.

[0010] The present invention was made in view of the following circumstances, and provides a fuel cell component and a method for manufacturing the same. In the fuel cell component having a fuel cell substrate and a sealing component, the sealing component can be firmly attached to the surface of the fuel cell substrate in an adhesive-free manner. Furthermore, the sealing component can be thin-film formed and exhibits excellent sealing performance over a wide temperature range.

[0011] means for solving problems

[0012] The inventors of this invention have conducted repeated and in-depth research to solve the aforementioned problems. During this research, it was discovered that by using a free radical-curable crosslinker as the sealing member, a fuel cell component can be provided that can be firmly and directly bonded (adhesive-free) to the surface of a fuel cell substrate. Furthermore, the sealing member can be thin-film-formed, achieving excellent sealing performance in fuel cells while satisfying properties such as aging resistance, elongation, and compression resistance over a wide temperature range. This free radical-curable crosslinker is formed from a composition consisting of a (meth)acrylic acid polymer (A) with (meth)acryloyl groups at the ends of its molecular chains as the main component, and in a specific ratio relative to the (meth)acrylic acid polymer (A), a monofunctional (meth)acrylic acid monomer (B) with a glass transition temperature (Tg) of 0°C or higher and a polycyclic structure, a monofunctional (meth)acrylic acid monomer (C) other than (B), a polyfunctional (meth)acrylic acid monomer (D), and a free radical polymerization initiator (E). The glass transition temperature (Tg) is below -30°C.

[0013] However, the main point of the present invention is in the following [1] to

[10] .

[0014] [1] A fuel cell component comprising a fuel cell substrate and a sealing member, wherein the sealing member is directly fixed to the surface of the fuel cell substrate, wherein...

[0015] The sealing component is a crosslinked body of a free radical curable composition, wherein the free radical curable composition contains component (D) in a ratio of 1 to 10 parts by weight relative to component (A) below, and component (E) in a ratio of 0.01 to 10 parts by weight below, and the content of component (B) below is 5 to 25% by weight relative to the total weight of components (A) to (C) below. The glass transition temperature (Tg) of the crosslinked body is below -30°C.

[0016] (A) A (meth)acrylic acid polymer having (meth)acryloyl groups at the ends of its molecular chains.

[0017] (B) Monofunctional (meth)acrylic acid monomers with a glass transition temperature (Tg) above 0°C and a polycyclic structure.

[0018] (C) Monofunctional (meth)acrylic acid monomers other than those described in (B),

[0019] (D) Multifunctional (meth)acrylic acid monomers,

[0020] (E) Free radical polymerization initiator.

[0021] [2] According to the fuel cell component of [1], wherein the polycyclic structure in component (B) is composed of a polycyclic structure having 10 or more carbon atoms.

[0022] [3] The fuel cell component according to [1] or [2], wherein the proportion of component (C) in the free radical curing composition is in the range of 0 to 75 parts by weight relative to 100 parts by weight of component (A).

[0023] [4] A fuel cell component according to any one of [1] to [3], wherein the (D) component is at least one selected from the group consisting of 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate and pentaerythritol acrylate compounds.

[0024] [5] A fuel cell component according to any one of [1] to [4], wherein the free radical curing composition further contains silicon dioxide.

[0025] [6] The fuel cell component according to [5], wherein the silicon dioxide is at least one selected from the group consisting of dimethylsilylated silicon dioxide, trimethylsilylated silicon dioxide, octylsilylated silicon dioxide and methacryloxysilylated silicon dioxide.

[0026] [7] A fuel cell component according to any one of [1] to [6], wherein the free radical curing composition is an ultraviolet curing composition.

[0027] [8] A fuel cell component according to any one of [1] to [7], wherein the sealing component is a membrane-like sealing component.

[0028] [9] The fuel cell component according to [8], wherein the thickness of the membrane-like sealing component is 50 to 1,000 μm.

[0029]

[10] A method for manufacturing a fuel cell component, which is the method for manufacturing a fuel cell component according to any one of [1] to [9], wherein the method for manufacturing the fuel cell component comprises: a step of coating a free radical curable composition onto the surface of a fuel cell substrate, wherein the free radical curable composition contains component (D) in a ratio of 1 to 10 parts by weight relative to 100 parts by weight of component (A), contains component (E) in a ratio of 0.01 to 10 parts by weight, and the content of component (B) relative to the total weight of components (A) to (C) is 5 to 25% by weight; and a step of irradiating the coated area with active energy rays to crosslink the free radical curable composition to form a sealing component.

[0030] (A) A (meth)acrylic acid polymer having (meth)acryloyl groups at the ends of its molecular chains.

[0031] (B) Monofunctional (meth)acrylic acid monomers with a glass transition temperature (Tg) above 0°C and a polycyclic structure.

[0032] (C) Monofunctional (meth)acrylic acid monomers other than those described in (B),

[0033] (D) Multifunctional (meth)acrylic acid monomers,

[0034] (E) Free radical polymerization initiator.

[0035] Invention Effects

[0036] According to the present invention, a fuel cell component can be provided, which is formed by firmly and directly bonding the aforementioned sealing member (adhering tightly to the surface of the fuel cell substrate without adhesive) to the surface of the fuel cell substrate, and can realize the thin film formation of the aforementioned sealing member, and has excellent sealing performance over a wide temperature range. Attached Figure Description

[0037] Figure 1 This is a cross-sectional view showing an example of a fuel cell component of the present invention.

[0038] Figure 2 This is a cross-sectional view showing an example of a fuel cell component using the present invention. Detailed Implementation

[0039] Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited to these embodiments. Furthermore, in this specification, "(meth)acrylic acid" is a term used to encompass both acrylic acid and methacrylic acid; "(meth)acrylate" is a term used to encompass both acrylate and methacrylate; and "(meth)acryloyl" is a term used to encompass both acryloyl and methacryloyl groups. Additionally, "polymer" is a term used to encompass both copolymers and oligomers.

[0040] The fuel cell component of the present invention comprises a fuel cell substrate and a sealing component, wherein the sealing component is directly fixed to the surface of the fuel cell substrate.

[0041] The sealing component is a crosslinked body of a free radical curable composition, wherein the free radical curable composition contains component (D) in a ratio of 1 to 10 parts by weight relative to component (A) below, and component (E) in a ratio of 0.01 to 10 parts by weight below, and the content of component (B) below is 5 to 25% by weight relative to the total weight of components (A) to (C) below. The glass transition temperature (Tg) of the crosslinked body is below -30°C.

[0042] (A) A (meth)acrylic acid polymer having (meth)acryloyl groups at the ends of its molecular chains.

[0043] (B) Monofunctional (meth)acrylic acid monomers with a glass transition temperature (Tg) above 0°C and a polycyclic structure.

[0044] (C) Monofunctional (meth)acrylic acid monomers other than those in (B) above.

[0045] (D) Multifunctional (meth)acrylic acid monomers,

[0046] (E) Free radical polymerization initiator.

[0047] The components of the materials used as the sealing components described above will be explained below.

[0048] <(A)Component>

[0049] Component (A) is a (meth)acrylic acid polymer having (meth)acryloyl groups at the ends of its molecular chains. It is the main component of the free radical curable composition used as the material for the aforementioned sealing member, typically referring to a component comprising 45% by weight or more of the total composition, and preferably 50% by weight or more. Furthermore, from the viewpoint of the effects of the present invention, it is preferable that the polymer used in the aforementioned composition consists solely of component (A).

[0050] (A) The molecular chain (main chain) of the component is composed of homopolymers or copolymers of one or more (meth)acrylic acid monomers, or copolymers of one or more (meth)acrylic acid monomers and vinyl monomers that can copolymerize therewith.

[0051] Examples of the aforementioned (meth)acrylic acid monomers include, for example, (meth)acrylic acid, methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, n-pentyl (meth)acrylate, isopentyl (meth)acrylate, n-hexyl (meth)acrylate, cyclohexyl (meth)acrylate, n-heptyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, and dodecyl (meth)acrylate. These include methyl esters, tridecyl methacrylate, tetradecyl methacrylate, pentadecyl methacrylate, hexadecyl methacrylate, heptadecanyl methacrylate, stearyl methacrylate, isostearyl methacrylate, oleyl methacrylate, docosyl methacrylate, 2-decyltetradecyl methacrylate, phenyl methacrylate, toluyl methacrylate, toluyl methacrylate, 4-tert-butylcyclohexyl methacrylate, dicyclopentenyl methacrylate, dicyclopentenyloxyethyl methacrylate, dicyclopentyl methacrylate, dicyclopentyloxyethyl methacrylate, isobornyl methacrylate, etc. They can be used alone or copolymerized in multiple ways.

[0052] Alternatively, the above-mentioned (meth)acrylic acid monomer can be copolymerized with other monomers to further form a block copolymer. Examples of copolymerizable monomers include, for instance, styrene-based monomers such as styrene, fluorinated vinyl monomers such as perfluoroethylene, silane-based vinyl monomers such as vinyltrimethoxysilane, acrylonitrile, methacrylonitrile, and amide-based vinyl monomers such as acrylamide and methacrylamide.

[0053] In the above, preferred monomers are ethyl methacrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, etc., and more preferably are acrylate monomers with 2 to 14 carbon atoms in the ester group or methacrylate monomers with 8 to 14 carbon atoms in the ester group. If the number of carbon atoms in the ester group is outside the above range, a tendency for poor compression set at low temperatures can be observed. In particular, if the number of carbon atoms is greater than the above range, a tendency for poor reactivity during polymerization and difficulty in synthesis can be observed.

[0054] (A) The preferred component is a copolymer of (meth)acrylate monomers having (meth)acryloyl groups at the ends of the molecular chains, more preferably a copolymer obtained by free radical polymerization of (meth)acrylate monomers such as ethyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and stearyl (meth)acrylate. Particularly more preferred is a copolymer obtained by polymerizing n-butyl (meth)acrylate and 2-ethylhexyl (meth)acrylate.

[0055] As for the copolymerization ratio (weight ratio) of the above-mentioned (meth)acrylate monomers, for example, in the case of a copolymer obtained by polymerizing n-butyl acrylate and 2-ethylhexyl acrylate (n-butyl acrylate: 2-ethylhexyl acrylate), from the viewpoint of more effectively exerting the effects of the present invention, it is preferably 40:60 to 60:40.

[0056] (A) The component is a (meth)acrylic acid polymer having (meth)acryloyl groups at the ends of at least one of the molecular chains. From the viewpoint of more effectively exerting the effects of the present invention, it is preferred to be a (meth)acrylic acid polymer having (meth)acryloyl groups at both ends of the molecular chain.

[0057] From the viewpoint of more effectively utilizing the effects of the present invention, component (A) is preferably a compound represented by the following general formula (1).

[0058] [Chemistry 1]

[0059]

[0060] (In general formula (1), R1 is an ester residue with 1 to 20 hydrogen atoms or carbon atoms, R2 and R3 are organic groups with 1 to 20 hydrogen atoms or carbon atoms, and n is an integer from 20 to 800.)

[0061] In the above general formula (1), the ester residue having 1 to 20 carbon atoms can be any of the following: linear, branched, or cyclic. Examples include methyl ester residues, ethyl ester residues, n-propyl ester residues, isopropyl ester residues, n-butyl ester residues, isobutyl ester residues, tert-butyl ester residues, pentyl ester residues, hexyl ester residues, heptyl ester residues, octyl ester residues, cyclopentyl ester residues, and cyclohexyl ester residues. Among these, the ester residue having 2 to 14 carbon atoms is preferred. In addition, in general formula (1), the organic group can be an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, an aralkyl group having 7 to 20 carbon atoms, or an unsubstituted or substituted monovalent hydrocarbon group having 1 to 20 carbon atoms. From the viewpoint of improving reactivity, the organic group is preferably a hydrogen atom or an alkyl group, and more preferably a hydrogen atom or a methyl group. In addition, in general formula (1), n ​​is an integer from 20 to 800, preferably an integer from 50 to 400.

[0062] The above-mentioned ingredient (A) can be used alone or in combination with two or more ingredients.

[0063] The glass transition temperature (Tg) of component (A) is not particularly limited, but is preferably -40°C or lower, more preferably -50°C or lower. If the glass transition temperature (Tg) of component (A) is higher than the above-mentioned temperature, a tendency for poor compression set and other defects at low temperatures can be observed. Furthermore, the lower limit is not particularly limited, but is, for example, -100°C.

[0064] The glass transition temperature (Tg) of component (A) was determined using a differential scanning calorimeter (DSC). Specifically, a Seiko Instruments SSC-5200 differential scanning calorimeter was used. After a preliminary adjustment, the sample was temporarily heated to 200°C at a rate of 25°C / min, held for 10 minutes, and then cooled to 50°C at a rate of 25°C / min. Measurements were then taken during the period of heating to 200°C at a rate of 10°C / min. The integral value was calculated from the obtained DSC curve, and the glass transition temperature was determined from its maximum point.

[0065] Furthermore, the glass transition temperatures (Tg) of each component used in this invention, as well as the glass transition temperatures (Tg) of each component used in the embodiments and comparative examples described later, were also determined as described above.

[0066] (A) The number-average molecular weight (Mn) of the component is, for example, 5,000 to 100,000, more preferably 10,000 to 50,000. If the number-average molecular weight (Mn) is less than the above range, a tendency to have poor compressive cracking properties can be observed; if it is greater than the above range, a tendency to have poor compressive settling properties can be observed, and a tendency to exhibit high viscosity and reduced workability can be observed.

[0067] From the viewpoint of more effectively utilizing the effects of the present invention, the molecular weight distribution (weight-average molecular weight (Mw) / number-average molecular weight (Mn)) of component (A) is preferably 1.1 to 1.6, more preferably 1.1 to 1.4. Furthermore, the number-average molecular weight (Mn) and weight-average molecular weight (Mw) are determined by gel permeation chromatography (GPC). Specifically, chloroform is used as the mobile phase, and the determination is performed using a polystyrene gel column; the number-average molecular weight, etc., can be calculated from polystyrene.

[0068] From the viewpoint of more effectively utilizing the effects of the present invention, the viscosity of component (A) at 23°C is preferably 40 to 1,000 Pa·s, more preferably 100 to 800 Pa·s.

[0069] As a method for synthesizing component (A), known synthetic methods can be used, for example, by free radical polymerization of (meth)acrylic acid monomers. Among these, living radical polymerization and atom transfer radical polymerization are preferred.

[0070] In addition, ingredient (A) is also available as a commercially available product, such as RC-100C and RC-200C (both manufactured by Kaneka Corporation).

[0071] <(B) Ingredients>

[0072] The monofunctional (meth)acrylic acid monomer of component (B) is a monofunctional (meth)acrylic acid monomer with a glass transition temperature (Tg) of 0°C or higher and having a polycyclic structure (a (meth)acrylic acid ester compound having a (meth)acryloyl group in its molecular structure). Furthermore, from the viewpoint of further improving the effects of the present invention, the polycyclic structure in component (B) is preferably a polycyclic structure having 10 or more carbon atoms, more preferably a polycyclic structure having 10 to 16 carbon atoms, and even more preferably a polycyclic structure having 10 to 14 carbon atoms. Additionally, the polycyclic structure is preferably a bicyclic or tricyclic structure.

[0073] Furthermore, the glass transition temperature (Tg) of component (B) is preferably 0 to 150°C, more preferably 10 to 130°C. The glass transition temperature (Tg) of component (B) was measured, as described above, using a differential scanning calorimeter (DSC) on the homopolymer of the monofunctional (meth)acrylic acid monomer as component (B).

[0074] Furthermore, specific examples of the aforementioned component (B) include isobornyl methacrylate, dicyclopentenyloxyethyl methacrylate, dicyclopentyl acrylate, and dicyclopentenyl acrylate. These can be used alone or in combination of two or more. More preferably, isobornyl methacrylate and dicyclopentenyloxyethyl methacrylate are preferred.

[0075] The content of component (B) is 5 to 25% by weight relative to the total weight (100% by weight) of components (A) to (C). From the viewpoint of further improving the effect of the present invention, it is preferably 6 to 24% by weight, and more preferably 7 to 23% by weight. That is, if the content of component (B) is less than the above range, the desired adhesion (tightness) cannot be obtained, and if the content of component (B) is more than the above range, the compression set and other properties are poor.

[0076] <(C) Ingredients>

[0077] The monofunctional (meth)acrylate monomer as component (C) is a (meth)acrylate compound having a (meth)acryloyl group in its molecular structure, other than component (B) described above. Specifically, known olefinically unsaturated monofunctional monomers can be listed, such as (meth)acrylate monomers used as monomers constituting the main chain of (A) described above. From the viewpoint of further improving the effect of the present invention, alkyl acrylate monomers such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, n-pentyl methacrylate, n-heptyl methacrylate, 2-ethylhexyl methacrylate, n-octyl methacrylate, isooctyl methacrylate, nonyl methacrylate, isononyl methacrylate, decyl methacrylate, isodecyl methacrylate, lauryl methacrylate, tridecyl methacrylate, and stearyl methacrylate are preferred. More preferably, n-butyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, nonyl acrylate, isononyl acrylate, and isodecanyl acrylate. Particularly preferred are n-butyl acrylate and n-octyl acrylate.

[0078] The above-mentioned component (C) can be used alone or in combination with two or more components.

[0079] From the viewpoint of further improving the effect of the present invention, the content of component (C) is preferably 0 to 75 parts by weight, more preferably 0 to 50 parts by weight, relative to 100 parts by weight of component (A).

[0080] The glass transition temperature (Tg) of component (C) is not particularly limited, but is preferably below -40°C, more preferably below -50°C. If the glass transition temperature (Tg) of component (C) is higher than the above temperature, a tendency for poor compression set and other defects at low temperatures can be observed. Furthermore, the lower limit is not particularly limited, for example, -100°C. The glass transition temperature (Tg) of component (C) is determined by differential scanning calorimetry (DSC) of the homopolymer of the monofunctional (meth)acrylic acid monomer, which is component (C), in the same manner as described above.

[0081] <(D) Components>

[0082] (D) The polyfunctional (meth)acrylate monomer is a (meth)acrylate compound having two or more (meth)acryloyl groups in its molecular structure. Specifically, known olefinically unsaturated polyfunctional monomers can be listed as examples of (meth)acrylate monomers having two (meth)acryloyl groups in their molecular structure, such as 1,6-hexanediol di(meth)acrylate, 1,8-octanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, 1,12-dodecanediol di(meth)acrylate, 3-methyl-1,5-pentanediol di(meth)acrylate, and 2,4-diethyl-1,5-pentanediol di(meth)acrylate. Acrylic esters, butyl ethyl propylene glycol di(meth)acrylate, 3-methyl-1,7-octanediol di(meth)acrylate, 2-methyl-1,8-octanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, alkanediol di(meth)acrylates, ethoxylated cyclohexanediethanol di(meth)acrylate, ethoxylated bisphenol A di(meth)acrylate, tricyclodecanediethanol di(meth)acrylate, propoxylated ethoxylated bisphenol A di(meth)acrylate, 1,1,1-tris(hydroxymethyl)ethane di(meth)acrylate, etc.

[0083] Examples of (meth)acrylic acid monomers having three or more (meth)acryloyl groups include, for example, trimethylolpropane tri(meth)acrylate, trimethylolpropane ethoxytri(meth)acrylate, trimethylolpropane propoxytri(meth)acrylate, glycerol propoxytri(meth)acrylate, tetramethylolmethane tri(meth)acrylate, tetramethylolmethane tetra(meth)acrylate, di(trimethylolpropane)tetra(meth)acrylate, monopentaerythritol (meth)acrylate, dipentaerythritol (meth)acrylate, tripentaerythritol (meth)acrylate, polypentaerythritol (meth)acrylate, and other pentaerythritol acrylate compounds with pentaerythritol and (meth)acrylate structures.

[0084] From the viewpoint of further improving the effect of the present invention, the preferred components in (D) above are alkyl diol dimethacrylates and pentaerythritol acrylate compounds such as 1,6-hexanediol dimethacrylate, 1,8-octanediol dimethacrylate, 1,9-nonanediol dimethacrylate, 1,10-decanediol dimethacrylate, 1,12-dodecanediol dimethacrylate, 3-methyl-1,5-pentanediol dimethacrylate, 2,4-diethyl-1,5-pentanediol dimethacrylate, butylethylpropylene glycol dimethacrylate, 3-methyl-1,7-octanediol dimethacrylate, 2-methyl-1,8-octanediol dimethacrylate, neopentanediol dimethacrylate, etc. More preferably, they are 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, and pentaerythritol acrylate compounds.

[0085] (D) The polyfunctional (meth)acrylic acid monomer of component (D) preferably has 6 or more carbon atoms in its molecular chain (main chain). If the number of carbon atoms is less than the above value, a tendency for poor compressive cracking can be observed.

[0086] The above-mentioned component (D) can be used alone or in combination with two or more. For example, as a pentaerythritol acrylate compound, a mixture of tripentaerythritol acrylate, dipentaerythritol acrylate, monopentaerythritol acrylate and polypentaerythritol acrylate can be used.

[0087] The content of component (D) is 1 to 10 parts by weight relative to 100 parts by weight of component (A), and preferably 2 to 7.5 parts by weight from the viewpoint of further improving the effect of the present invention. That is, if the content of component (D) is less than the above range, the high-temperature compression set and other properties deteriorate, and if the content of component (D) is more than the above range, the compression resistance deteriorates.

[0088] <(E) Components>

[0089] As a free radical polymerization initiator for component (E), there are no particular limitations on compounds that generate free radicals by irradiation with energy rays. Examples include benzophenone, 4-methylbenzophenone, 2,4,6-trimethylbenzophenone, methyl o-benzoylbenzoate, 4-phenylbenzophenone and other benzophenone-type compounds, tert-butylanthraquinone, 2-ethylanthraquinone and other anthraquinone-type compounds, 2-hydroxy-2-methyl-1-phenylpropane-1-one, oligomer {2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propanone}, benzyl dimethyl ketal, 1-hydroxycyclohexylphenyl ketone, benzoin methyl ether, 2-methyl-[4-(methylthio)]propanone, etc. Alkyl phenyl ketones such as [phenyl]-2-morpholino-1-propanone and 2-hydroxy-1-{4-[4-(2-hydroxy-2-methylpropanoyl)benzyl]phenyl}-2-methylpropane-1-one; thioxanthones such as 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1, diethylthioxanthone, and isopropylthioxanthone; acylphosphine oxides such as 2,4,6-trimethylbenzoyl diphenylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide, and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide; and phenyl glyoxylates such as methyl phenylglyoxylate. From the viewpoint of excellent reactivity, alkyl phenyl ketones are preferred, specifically 1-hydroxycyclohexylphenyl ketone.

[0090] The above-mentioned component (E) can be used alone or in combination with two or more components.

[0091] The content of component (E) is 0.01 to 10 parts by weight relative to 100 parts by weight of component (A), wherein, preferably, it is 0.1 to 10 parts by weight.

[0092] <Various Additives>

[0093] In the materials of the sealing components involved in the fuel cell components of the present invention, in addition to the components (A) to (E) mentioned above, various additives such as fillers (F), anti-aging agents (G), compatibilizers, curing modifiers, lubricants, pigments, defoamers, foaming agents, light stabilizers, and surface modifiers may be added without impairing the effects of the present invention.

[0094] <(F)Component>

[0095] The filler used as component (F) is not particularly limited and can include silica, carbon black, calcium carbonate, titanium dioxide, talc, clay, and hollow glass spheres, among which silica is preferred from the viewpoint of excellent reinforcing properties. Furthermore, from the viewpoint of improving dispersibility, silica that has been hydrophobically treated with a surface treatment agent is more preferred. For example, silica that has been surface-treated with a silane compound is preferred, and more preferably is dimethylsilylated silica treated with dimethylsilane, trimethylsilylated silica treated with trimethylsilane, octylsilylated silica treated with octylsilane, or methacryloxysilane treated with methacryloxysilane. Trimethylsilylated silica and methacryloxysilylated silica are particularly preferred.

[0096] Commercially available products that are components of (F) include, for example, "AEROSIL RX200" (manufactured by AEROSIL Corporation) as trimethylsilylated silica, and "AEROSILR7200" (manufactured by AEROSIL Corporation) as methacryloxysilylated silica.

[0097] The above-mentioned component (F) can be used alone or in combination with two or more components.

[0098] When component (F) is present, its content is not particularly limited, but is usually 1 to 30 parts by weight relative to 100 parts by weight of component (A). If the content of component (F) exceeds the above range, it tends to exhibit high viscosity and poor workability.

[0099] <(G) component>

[0100] As an anti-aging agent for component (G), there are no particular limitations, but examples include N-phenyl-1-naphthylamine, N,N'-diphenyl-p-phenylenediamine, N,N'-di-2-naphthyl-p-phenylenediamine, N-phenyl-N'-isopropyl-p-phenylenediamine, di(4-octylphenyl)amine, 4,4'-bis(α,α-dimethylbenzyl)diphenylamine, p-(p-toluenesulfonamide)diphenylamine, N-phenyl-N'-(1,3-dimethylbutyl)p-phenylenediamine and other amine-based anti-aging agents, 2,6-di-tert-butyl-4-methylphenol, 2,6-di-tert-butyl-4-ethylphenol, 2,6-di-tert-butylphenol, 2,4,6-tri-tert-butylphenol, styrylated phenol, 2,2'-aminophenol, etc. Phenolic anti-aging agents such as methylbis(4-methyl-6-tert-butylphenol), 2,2'-methylenebis(4-ethyl-6-tert-butylphenol), 4,4'-thiobis(3-methyl-6-tert-butylphenol), 4,4'-butylidenebis(3-methyl-6-tert-butylphenol), 4,4'-methylenebis(2,6-tert-butylphenol), 4,4'-isopropylidenebis(2,6-di-tert-butylphenol), and 2,2'-isobutylidenebis(4,6-dimethylphenol); imidazole anti-aging agents such as 2-mercaptobenzimidazole, 2-mercaptobenzimidazole zinc salt, and 2-mercaptomethylbenzimidazole; and sulfur-based anti-aging agents such as dilauryl thiodipropionate and distearate thiodipropionate. The preferred anti-aging agents are amine-based and phenol-based, with 4,4'-bis(α,α-dimethylbenzyl)diphenylamine being the most preferred.

[0101] The above-mentioned component (G) can be used alone or in combination with two or more components.

[0102] When the (G) component is present, its content is not particularly limited, and it is usually 0.1 to 10 parts by weight relative to 100 parts by weight of the (A) component, preferably 0.5 to 5 parts by weight.

[0103] <Preparation Method of Free Radical Curable Composition>

[0104] The free radical curable composition used as the material for the sealing member involved in the fuel cell component of the present invention is prepared, for example, by adding component (A) to a substance prepared by mixing components (B) to (E) and various additives such as components (F) and (G) as needed, and then mixing using a mixer. Alternatively, when silica or the like is used as component (F), it is manufactured, for example, by adding component (A) in which component (F) is dispersed to a substance prepared by mixing components (B) to (E) and various additives, and then mixing using a mixer.

[0105] <Manufacturing Method of Components for Fuel Cells>

[0106] The fuel cell component of the present invention can be manufactured by coating the free radical curable composition prepared as described above onto the surface of a fuel cell substrate, irradiating the coated area with active energy rays to crosslink the free radical curable composition, thereby forming a sealing component. The coating method for the free radical curable composition is not particularly limited; various methods such as dispensers, spraying, inkjet printing, and screen printing can be used. More specifically, sealing methods such as FIPG (Fixed In-Situ Gasket), CIPG (Cure In-Situ Gasket), and MIPG (Molded In-Situ Gasket) can be used. The active energy rays can be electron beams, ultraviolet light, etc., with ultraviolet light being more preferred as it causes less damage to the fuel cell substrate. Known active energy sources can be used as the active energy source for the active energy rays, such as high-pressure mercury lamps, black light lamps, LEDs, and fluorescent lamps. Furthermore, the free radical curable composition can be crosslinked by active energy rays such as electron beams and ultraviolet light; if necessary, it can also be crosslinked by auxiliary heating.

[0107] The glass transition temperature (Tg) of the crosslinked body (sealing member) of the above-described free radical curable composition is -30°C or lower. From the viewpoint of further improving the effect of the present invention, the glass transition temperature (Tg) is more preferably -35°C or lower. Furthermore, the lower limit of the glass transition temperature (Tg) is not particularly limited, for example, it is -100°C. This glass transition temperature (Tg) is measured by differential scanning calorimetry (DSC) in the same manner as described above.

[0108] Here, an example (cross-sectional view) of a fuel cell component of the present invention is shown. Figure 1 .exist Figure 1 In this process, a separator 5, which is a rectangular thin plate with a total of six grooves extending along its length and has a concave-convex cross-section, is used as the substrate for a fuel cell. Then, a free radical curable composition prepared as described above is coated on the periphery of the separator 5, and the coated area is irradiated with active energy rays to crosslink it. This allows a rectangular lip 4b (sealing member) with a convex cross-section to be formed in a state of being firmly and directly bonded (tightly attached without adhesive) to the surface (periphery) of the separator 5.

[0109] Furthermore, the substrates used in fuel cells vary depending on the type and structure of the fuel cell. In addition to the separators (metal separators, carbon separators, etc.) mentioned above, other examples include gas diffusion layers, MEAs (electrolyte membranes, electrodes), etc.

[0110] Furthermore, the crosslinked body (sealing member) of the above-mentioned free radical curable composition can be easily formed into a film-like sealing member. Through the thinning of the sealing member, miniaturization of the fuel cell can be achieved. Specifically, the thickness of the film-like sealing member can be easily thinned to 50–1,000 μm (preferably 75–900 μm, more preferably 100–800 μm), enabling miniaturization of the fuel cell. Moreover, the above-mentioned sealing member can satisfy characteristics such as aging resistance, elongation, and compression resistance over a wide temperature range, achieving excellent sealing performance.

[0111] <Fuel Cells>

[0112] Furthermore, fuel cells can be manufactured using the fuel cell components obtained as described above. Figure 2 The illustration primarily shows a single cell 1 in a fuel cell composed of multiple stacked cells. Cell 1 includes an MEA2, a gas diffusion layer 3, a sealing member 4, and a separator 5. Furthermore, the separator 5 constituting the cell 1 is sealed to the end of the MEA2 by the sealing member 4.

[0113] The aforementioned sealing member 4 is integrally manufactured with the separator 5 and MEA2 using the manufacturing method described above. Furthermore, due to the excellent adhesion of the sealing member 4, the two sealing members 4 shown in the figure adhere tightly even without an adhesive layer, allowing for integral manufacturing of the cell 1. Since no additional adhesive layer is required, this simplifies the fuel cell manufacturing process. Moreover, in Figure 2 In the example, sealing member 4 uses two separate members, but it could also be a single sealing member that combines the two.

[0114] Although not illustrated, MEA2 consists of an electrolyte membrane and a pair of electrodes sandwiched between it and disposed on both sides of the stacking direction. The electrolyte membrane and the pair of electrodes are rectangular thin plates. Gas diffusion layers 3 are disposed between MEA2 on both sides of the stacking direction. Gas diffusion layers 3 are porous layers and are rectangular thin plates.

[0115] The separator 5 is preferably a carbon separator or a metal separator. From the viewpoint of conductivity reliability, a metal separator having a carbon thin film such as a DLC film (diamond-like carbon film) or a graphite film is particularly preferred. The separator 5 is a rectangular thin plate with a total of six grooves extending in the length direction, giving the separator 5 a concave-convex cross-section. The separator 5 is arranged opposite each other on both sides of the gas diffusion layer 3 in the stacking direction. Between the gas diffusion layer 3 and the separator 5, a gas flow path 6 for supplying gas to the electrode is defined by the concave-convex shape.

[0116] When a fuel cell, such as a solid polymer fuel cell, is operating, fuel gas and oxidant gas are supplied separately through gas flow path 6. Here, the periphery of MEA2 is sealed by sealing member 4. Therefore, gas mixing and leakage are prevented.

[0117] Example

[0118] Hereinafter, embodiments will be described together with comparative examples. However, the present invention is not limited to these embodiments without departing from its spirit.

[0119] First, before the embodiments and comparative examples, prepare the materials shown below.

[0120] <(A)Component>

[0121] Acryloyl-terminated polyacrylate A1 (synthesis example)

[0122] Following a known method (e.g., as described in Japanese Patent Application Publication No. 2012-211216), cuprous bromide was used as a catalyst, pentamethyldiethylenetriamine as a ligand, and diethyl-2,5-dibromohexane as a free radical polymerization initiator. Using 50 parts by weight of 2-ethylhexyl acrylate / n-butyl acrylate as the acrylic monomer, polymerization was carried out at a monomer / initiator molar ratio of 180 to obtain a terminal bromoacrylate-2-ethylhexyl acrylate / n-butyl acrylate copolymer. This copolymer was dissolved in N,N-dimethylacetamide, potassium acrylate was added, and the mixture was heated and stirred at 70°C under a nitrogen atmosphere. After removing N,N-dimethylacetamide from the mixture by vacuum distillation, butyl acetate was added to the residue, and insoluble components were removed by filtration. The butyl acetate in the filtrate was removed by vacuum distillation to obtain a terminal acryloyl acrylate-2-ethylhexyl acrylate / n-butyl acrylate copolymer [A1]. The number-average molecular weight is 23,000, and the molecular weight distribution is 1.1. (The last part, "in the process of passing through...", appears to be an unrelated fragment and is omitted from the translation.) 1 When H-NMR analysis determined the average number of acryloyl groups introduced per polymer molecule, it was approximately 1.9. Additionally, the glass transition temperature (Tg) is -50°C.

[0123] <(B) Ingredients>

[0124] Dicyclopentenoxyethyl acrylate (Tg: 10-15℃, manufactured by Hitachi Chemical Co., Ltd.) and isobornyl acrylate (Tg: 97℃, manufactured by Hitachi Chemical Co., Ltd.)

[0125] <(C) Ingredients>

[0126] Octyl acrylate (Tg: -65℃, manufactured by Osaka Organic Chemicals Co., Ltd.)

[0127] <(D) Components>

[0128] 1,9-Nonadiol diacrylate (manufactured by Osaka Organic Chemicals Co., Ltd.)

[0129] <(E) Components>

[0130] 1-Hydroxycyclohexylphenyl ketone (manufactured by iGM RESINS, Omnirad 184)

[0131] [Examples 1-8, Comparative Examples 1-6]

[0132] The components shown in Tables 1 and 2 (described below) are combined in the proportions shown in the tables and mixed using a planetary mixer (manufactured by Inoue Manufacturing Co., Ltd.) to prepare a free radical curable composition.

[0133] In addition, the free radical curable compositions obtained above were irradiated with ultraviolet light (irradiation intensity: 250 mW / cm) using a high-pressure mercury UV irradiation machine (Heraeus F600V-10). 2 Cumulative light intensity: 3000 mJ / cm 2 The glass transition temperature (Tg) of the crosslinked samples was determined using differential scanning calorimetry (DSC). The results are shown in Table 1 and Table 2.

[0134] Then, for each free radical curable composition obtained above, its properties were evaluated according to the following criteria. The results are shown in Table 1 and Table 2.

[0135] Adhesiveness

[0136] The free radical curable compositions were irradiated with ultraviolet light using a high-pressure mercury UV irradiation machine (Heraeus, F600V-10) (irradiation intensity: 250mW / cm²). 2 Cumulative light intensity: 3000 mJ / cm 2 A test sample with a thickness of 1 mm was obtained. Then, at room temperature (25°C), for the above test sample, the SUS304 test piece was pressed in at a speed of 0.5 mm / s with a compressive force of 0.8 MPa using a fixing simulator FSR-1000 manufactured by RHESCA, held for 10 seconds, and then the peel force when lifted at a speed of 15 mm / s was measured. The adhesion was evaluated according to the following criteria.

[0137] ◎: Peel strength is above 1.0 MPa (Excellent)

[0138] ○: Peel strength is 0.9 MPa or higher and less than 1.0 MPa (very good)

[0139] Δ: Peel strength is above 0.8 MPa and less than 0.9 MPa (good)

[0140] ×: Peel strength less than 0.8 MPa (poor)

[0141] Low-Temperature Compression Permanent Deformation

[0142] Under the same conditions as those used in the adhesion test, test samples with a diameter of 15 mm and a thickness of 1 mm were obtained using various free radical curing compositions. Then, a compression set test at low temperature according to JIS K 6262 was performed on these test samples. Specifically, each sample was compressed at a compression rate of 25%, stored at -30°C for 24 hours, and then the compression was released at -30°C. The thickness of each sample was measured after 30 minutes at this temperature, and the compression set (%) was calculated and evaluated according to the following criteria.

[0143] ◎: Less than 30% (Excellent)

[0144] ○: 30% or more but less than 40% (Very good)

[0145] Δ: 40% or more but less than 50% (good)

[0146] ×: More than 50% (poor)

[0147] Low-Temperature Compression Cracks

[0148] In the aforementioned low-temperature compression set test, the compression ratio was changed to 50%. Otherwise, the test was conducted under the same conditions as the previous test, and each sample was visually inspected for cracks.

[0149] ○: No cracks (Good)

[0150] ×: Cracks present (poor quality)

[0151] High-Temperature Compression Permanent Deformation

[0152] Under the same conditions as those used in the adhesion test, test samples with a diameter of 15 mm and a thickness of 1 mm were obtained using various free radical curable compositions. Then, compression set tests were performed on these test samples at high temperatures according to JIS K 6262. Specifically, each sample was compressed at a compression ratio of 25%, heated at 120°C for 24 hours under this condition, and then the compression was released. The thickness of each sample was measured after 30 minutes at room temperature (25°C), and the compression set (%) was calculated and evaluated according to the following criteria.

[0153] ◎: Less than 20% (Excellent)

[0154] ○: 20% or more but less than 25% (Very good)

[0155] Δ: 25% or more but less than 30% (good)

[0156] ×: More than 30% (poor)

[0157] High-temperature compression cracking

[0158] In the high-temperature compression set test described above, the compression ratio was changed to 50%. Otherwise, the test was conducted under the same conditions as the previous test, and each sample was visually inspected for cracks.

[0159] ○: No cracks (Good)

[0160] ×: Cracks present (poor quality)

[0161] Table 1

[0162] (parts by weight)

[0163]

[0164] Table 2

[0165] (parts by weight)

[0166]

[0167] As can be seen from the results in Table 1 above, in Examples 1 to 8 that meet the requirements specified in this invention, the evaluations of adhesion (tightness), compression set at low temperatures, and compression crack resistance are excellent, and good results are also obtained in the evaluations of compression set at high temperatures and compression crack resistance. Therefore, they can perform excellently as sealing materials for fuel cell components.

[0168] In contrast, as shown in Table 2 above, Comparative Example 1, lacking component (B) of the present invention, resulted in poor adhesion (tightness) evaluation. In Comparative Examples 2 and 4, the value of [(B) / {(A)+(B)+(C)}] was less than the range specified in the present invention, thus resulting in poor adhesion (tightness) evaluation. In Comparative Example 3, the value of [(B) / {(A)+(B)+(C)}] was greater than the range specified in the present invention, resulting in poor evaluation of compression set, etc. In Comparative Example 5, the content of component (D) of the present invention was less than the range specified in the present invention, resulting in poor evaluation of high-temperature compression set. In Comparative Example 6, the content of component (D) of the present invention was greater than the range specified in the present invention, resulting in observable compression cracks at both low and high temperatures. Therefore, in these comparative examples, the performance as a sealing material for fuel cell components as described in the above embodiments could not be achieved.

[0169] Furthermore, while the above embodiments illustrate specific aspects of the invention, these embodiments are merely examples and not intended to be limiting. It is intended that various modifications as understood by those skilled in the art be included within the scope of this invention.

[0170] Industrial applicability

[0171] The fuel cell component of the present invention is used to construct components for fuel cells, for example, a component formed by integrally integrating a fuel cell substrate such as a metal separator and a rubber sealing member that seals it in a non-adhesive manner. Therefore, it can be used in seals and the like where the use of adhesives is a concern.

[0172] Explanation of reference numerals in the attached figures

[0173] 4b: Lip (sealing component);

[0174] 5: Partition.

Claims

1. A fuel cell component comprising a fuel cell substrate and a sealing member, wherein the sealing member is directly fixed to the surface of the fuel cell substrate, wherein... The sealing component is a crosslinked body of a free radical curable composition, wherein the free radical curable composition contains, relative to 100 parts by weight of component (A), component (C) in a ratio of 0 to 75 parts by weight, component (D) in a ratio of 1 to 10 parts by weight, and component (E) in a ratio of 0.01 to 10 parts by weight, and the content of component (B) relative to the total weight of components (A) to (C) is 5 to 25% by weight, and the glass transition temperature (Tg) of the crosslinked body is below -30°C. (A) A (meth)acrylyl)acrylic acid polymer having (meth)acryloyl groups at the ends of its molecular chains. (B) Monofunctional (meth)acrylic acid monomers with a glass transition temperature (Tg) above 0°C and a polycyclic structure. (C) Monofunctional (meth)acrylic acid monomers other than those described in (B), (D) Multifunctional (meth)acrylic acid monomers, (E) Free radical polymerization initiator, The free radical curable composition further contains silicon dioxide in a ratio of 1 to 30 parts by weight relative to 100 parts by weight of component (A), wherein the silicon dioxide is at least one selected from the group consisting of dimethylsilylated silicon dioxide, trimethylsilylated silicon dioxide, octylsilylated silicon dioxide and methacrylsilylated silicon dioxide.

2. The member for fuel cells according to claim 1, wherein The polycyclic structure in component (B) consists of a polycyclic structure with 10 or more carbon atoms.

3. The member for fuel cells according to claim 1 or 2, wherein The (D) component is at least one selected from the group consisting of 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate and pentaerythritol acrylate compounds.

4. The member for fuel cells according to claim 1 or 2, wherein The free radical curable composition is an ultraviolet curable composition.

5. The fuel cell component according to claim 1 or 2, wherein, The sealing component is a membrane-like sealing component.

6. The fuel cell component according to claim 5, wherein, The thickness of the membrane-like sealing member is 50~1,000 μm.

7. A method for manufacturing a component for a fuel cell, comprising the method for manufacturing a component for a fuel cell according to any one of claims 1 to 6, wherein, The method for manufacturing the fuel cell component includes: a step of coating a free radical curable composition onto the surface of a fuel cell substrate, wherein the free radical curable composition contains component (D) in a ratio of 1 to 10 parts by weight relative to component (A), and component (E) in a ratio of 0.01 to 10 parts by weight, and the content of component (B) relative to the total weight of components (A) to (C) is 5 to 25% by weight; and a step of irradiating the coated area with active energy rays to crosslink the free radical curable composition to form a sealing component. (A) A (meth)acrylyl)acrylic acid polymer having (meth)acryloyl groups at the ends of its molecular chains. (B) Monofunctional (meth)acrylic acid monomers with a glass transition temperature (Tg) above 0°C and a polycyclic structure. (C) Monofunctional (meth)acrylic acid monomers other than those described in (B), (D) Multifunctional (meth)acrylic acid monomers, (E) Free radical polymerization initiator.

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